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 "code/codeCache.hpp" 29 #include "code/icBuffer.hpp" 30 #include "gc/g1/g1Allocator.inline.hpp" 31 #include "gc/g1/g1BarrierSet.hpp" 32 #include "gc/g1/g1CollectedHeap.inline.hpp" 33 #include "gc/g1/g1CollectionSet.hpp" 34 #include "gc/g1/g1CollectorPolicy.hpp" 35 #include "gc/g1/g1CollectorState.hpp" 36 #include "gc/g1/g1ConcurrentRefine.hpp" 37 #include "gc/g1/g1ConcurrentRefineThread.hpp" 38 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp" 39 #include "gc/g1/g1EvacStats.inline.hpp" 40 #include "gc/g1/g1FullCollector.hpp" 41 #include "gc/g1/g1GCPhaseTimes.hpp" 42 #include "gc/g1/g1HeapSizingPolicy.hpp" 43 #include "gc/g1/g1HeapTransition.hpp" 44 #include "gc/g1/g1HeapVerifier.hpp" 45 #include "gc/g1/g1HotCardCache.hpp" 46 #include "gc/g1/g1MemoryPool.hpp" 47 #include "gc/g1/g1OopClosures.inline.hpp" 48 #include "gc/g1/g1ParScanThreadState.inline.hpp" 49 #include "gc/g1/g1Policy.hpp" 50 #include "gc/g1/g1RegionToSpaceMapper.hpp" 51 #include "gc/g1/g1RemSet.hpp" 52 #include "gc/g1/g1RootClosures.hpp" 53 #include "gc/g1/g1RootProcessor.hpp" 54 #include "gc/g1/g1SATBMarkQueueSet.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/oopStorageParState.hpp" 73 #include "gc/shared/parallelCleaning.hpp" 74 #include "gc/shared/preservedMarks.inline.hpp" 75 #include "gc/shared/suspendibleThreadSet.hpp" 76 #include "gc/shared/referenceProcessor.inline.hpp" 77 #include "gc/shared/taskqueue.inline.hpp" 78 #include "gc/shared/weakProcessor.inline.hpp" 79 #include "logging/log.hpp" 80 #include "memory/allocation.hpp" 81 #include "memory/iterator.hpp" 82 #include "memory/metaspaceShared.inline.hpp" 83 #include "memory/resourceArea.hpp" 84 #include "oops/access.inline.hpp" 85 #include "oops/compressedOops.inline.hpp" 86 #include "oops/oop.inline.hpp" 87 #include "runtime/atomic.hpp" 88 #include "runtime/flags/flagSetting.hpp" 89 #include "runtime/handles.inline.hpp" 90 #include "runtime/init.hpp" 91 #include "runtime/orderAccess.hpp" 92 #include "runtime/threadSMR.hpp" 93 #include "runtime/vmThread.hpp" 94 #include "utilities/align.hpp" 95 #include "utilities/globalDefinitions.hpp" 96 #include "utilities/stack.inline.hpp" 97 98 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 99 100 // INVARIANTS/NOTES 101 // 102 // All allocation activity covered by the G1CollectedHeap interface is 103 // serialized by acquiring the HeapLock. This happens in mem_allocate 104 // and allocate_new_tlab, which are the "entry" points to the 105 // allocation code from the rest of the JVM. (Note that this does not 106 // apply to TLAB allocation, which is not part of this interface: it 107 // is done by clients of this interface.) 108 109 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 110 private: 111 size_t _num_dirtied; 112 G1CollectedHeap* _g1h; 113 G1CardTable* _g1_ct; 114 115 HeapRegion* region_for_card(jbyte* card_ptr) const { 116 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr)); 117 } 118 119 bool will_become_free(HeapRegion* hr) const { 120 // A region will be freed by free_collection_set if the region is in the 121 // collection set and has not had an evacuation failure. 122 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 123 } 124 125 public: 126 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(), 127 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { } 128 129 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 130 HeapRegion* hr = region_for_card(card_ptr); 131 132 // Should only dirty cards in regions that won't be freed. 133 if (!will_become_free(hr)) { 134 *card_ptr = G1CardTable::dirty_card_val(); 135 _num_dirtied++; 136 } 137 138 return true; 139 } 140 141 size_t num_dirtied() const { return _num_dirtied; } 142 }; 143 144 145 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 146 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 147 } 148 149 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 150 // The from card cache is not the memory that is actually committed. So we cannot 151 // take advantage of the zero_filled parameter. 152 reset_from_card_cache(start_idx, num_regions); 153 } 154 155 156 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 157 MemRegion mr) { 158 return new HeapRegion(hrs_index, bot(), mr); 159 } 160 161 // Private methods. 162 163 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 164 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 165 "the only time we use this to allocate a humongous region is " 166 "when we are allocating a single humongous region"); 167 168 HeapRegion* res = _hrm.allocate_free_region(is_old); 169 170 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 171 // Currently, only attempts to allocate GC alloc regions set 172 // do_expand to true. So, we should only reach here during a 173 // safepoint. If this assumption changes we might have to 174 // reconsider the use of _expand_heap_after_alloc_failure. 175 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 176 177 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 178 word_size * HeapWordSize); 179 180 if (expand(word_size * HeapWordSize)) { 181 // Given that expand() succeeded in expanding the heap, and we 182 // always expand the heap by an amount aligned to the heap 183 // region size, the free list should in theory not be empty. 184 // In either case allocate_free_region() will check for NULL. 185 res = _hrm.allocate_free_region(is_old); 186 } else { 187 _expand_heap_after_alloc_failure = false; 188 } 189 } 190 return res; 191 } 192 193 HeapWord* 194 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 195 uint num_regions, 196 size_t word_size) { 197 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 198 assert(is_humongous(word_size), "word_size should be humongous"); 199 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 200 201 // Index of last region in the series. 202 uint last = first + num_regions - 1; 203 204 // We need to initialize the region(s) we just discovered. This is 205 // a bit tricky given that it can happen concurrently with 206 // refinement threads refining cards on these regions and 207 // potentially wanting to refine the BOT as they are scanning 208 // those cards (this can happen shortly after a cleanup; see CR 209 // 6991377). So we have to set up the region(s) carefully and in 210 // a specific order. 211 212 // The word size sum of all the regions we will allocate. 213 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 214 assert(word_size <= word_size_sum, "sanity"); 215 216 // This will be the "starts humongous" region. 217 HeapRegion* first_hr = region_at(first); 218 // The header of the new object will be placed at the bottom of 219 // the first region. 220 HeapWord* new_obj = first_hr->bottom(); 221 // This will be the new top of the new object. 222 HeapWord* obj_top = new_obj + word_size; 223 224 // First, we need to zero the header of the space that we will be 225 // allocating. When we update top further down, some refinement 226 // threads might try to scan the region. By zeroing the header we 227 // ensure that any thread that will try to scan the region will 228 // come across the zero klass word and bail out. 229 // 230 // NOTE: It would not have been correct to have used 231 // CollectedHeap::fill_with_object() and make the space look like 232 // an int array. The thread that is doing the allocation will 233 // later update the object header to a potentially different array 234 // type and, for a very short period of time, the klass and length 235 // fields will be inconsistent. This could cause a refinement 236 // thread to calculate the object size incorrectly. 237 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 238 239 // Next, pad out the unused tail of the last region with filler 240 // objects, for improved usage accounting. 241 // How many words we use for filler objects. 242 size_t word_fill_size = word_size_sum - word_size; 243 244 // How many words memory we "waste" which cannot hold a filler object. 245 size_t words_not_fillable = 0; 246 247 if (word_fill_size >= min_fill_size()) { 248 fill_with_objects(obj_top, word_fill_size); 249 } else if (word_fill_size > 0) { 250 // We have space to fill, but we cannot fit an object there. 251 words_not_fillable = word_fill_size; 252 word_fill_size = 0; 253 } 254 255 // We will set up the first region as "starts humongous". This 256 // will also update the BOT covering all the regions to reflect 257 // that there is a single object that starts at the bottom of the 258 // first region. 259 first_hr->set_starts_humongous(obj_top, word_fill_size); 260 _g1_policy->remset_tracker()->update_at_allocate(first_hr); 261 // Then, if there are any, we will set up the "continues 262 // humongous" regions. 263 HeapRegion* hr = NULL; 264 for (uint i = first + 1; i <= last; ++i) { 265 hr = region_at(i); 266 hr->set_continues_humongous(first_hr); 267 _g1_policy->remset_tracker()->update_at_allocate(hr); 268 } 269 270 // Up to this point no concurrent thread would have been able to 271 // do any scanning on any region in this series. All the top 272 // fields still point to bottom, so the intersection between 273 // [bottom,top] and [card_start,card_end] will be empty. Before we 274 // update the top fields, we'll do a storestore to make sure that 275 // no thread sees the update to top before the zeroing of the 276 // object header and the BOT initialization. 277 OrderAccess::storestore(); 278 279 // Now, we will update the top fields of the "continues humongous" 280 // regions except the last one. 281 for (uint i = first; i < last; ++i) { 282 hr = region_at(i); 283 hr->set_top(hr->end()); 284 } 285 286 hr = region_at(last); 287 // If we cannot fit a filler object, we must set top to the end 288 // of the humongous object, otherwise we cannot iterate the heap 289 // and the BOT will not be complete. 290 hr->set_top(hr->end() - words_not_fillable); 291 292 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 293 "obj_top should be in last region"); 294 295 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 296 297 assert(words_not_fillable == 0 || 298 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 299 "Miscalculation in humongous allocation"); 300 301 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 302 303 for (uint i = first; i <= last; ++i) { 304 hr = region_at(i); 305 _humongous_set.add(hr); 306 _hr_printer.alloc(hr); 307 } 308 309 return new_obj; 310 } 311 312 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 313 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 314 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 315 } 316 317 // If could fit into free regions w/o expansion, try. 318 // Otherwise, if can expand, do so. 319 // Otherwise, if using ex regions might help, try with ex given back. 320 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 321 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 322 323 _verifier->verify_region_sets_optional(); 324 325 uint first = G1_NO_HRM_INDEX; 326 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 327 328 if (obj_regions == 1) { 329 // Only one region to allocate, try to use a fast path by directly allocating 330 // from the free lists. Do not try to expand here, we will potentially do that 331 // later. 332 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 333 if (hr != NULL) { 334 first = hr->hrm_index(); 335 } 336 } else { 337 // Policy: Try only empty regions (i.e. already committed first). Maybe we 338 // are lucky enough to find some. 339 first = _hrm.find_contiguous_only_empty(obj_regions); 340 if (first != G1_NO_HRM_INDEX) { 341 _hrm.allocate_free_regions_starting_at(first, obj_regions); 342 } 343 } 344 345 if (first == G1_NO_HRM_INDEX) { 346 // Policy: We could not find enough regions for the humongous object in the 347 // free list. Look through the heap to find a mix of free and uncommitted regions. 348 // If so, try expansion. 349 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 350 if (first != G1_NO_HRM_INDEX) { 351 // We found something. Make sure these regions are committed, i.e. expand 352 // the heap. Alternatively we could do a defragmentation GC. 353 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", 354 word_size * HeapWordSize); 355 356 _hrm.expand_at(first, obj_regions, workers()); 357 g1_policy()->record_new_heap_size(num_regions()); 358 359 #ifdef ASSERT 360 for (uint i = first; i < first + obj_regions; ++i) { 361 HeapRegion* hr = region_at(i); 362 assert(hr->is_free(), "sanity"); 363 assert(hr->is_empty(), "sanity"); 364 assert(is_on_master_free_list(hr), "sanity"); 365 } 366 #endif 367 _hrm.allocate_free_regions_starting_at(first, obj_regions); 368 } else { 369 // Policy: Potentially trigger a defragmentation GC. 370 } 371 } 372 373 HeapWord* result = NULL; 374 if (first != G1_NO_HRM_INDEX) { 375 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size); 376 assert(result != NULL, "it should always return a valid result"); 377 378 // A successful humongous object allocation changes the used space 379 // information of the old generation so we need to recalculate the 380 // sizes and update the jstat counters here. 381 g1mm()->update_sizes(); 382 } 383 384 _verifier->verify_region_sets_optional(); 385 386 return result; 387 } 388 389 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size, 390 size_t requested_size, 391 size_t* actual_size) { 392 assert_heap_not_locked_and_not_at_safepoint(); 393 assert(!is_humongous(requested_size), "we do not allow humongous TLABs"); 394 395 return attempt_allocation(min_size, requested_size, actual_size); 396 } 397 398 HeapWord* 399 G1CollectedHeap::mem_allocate(size_t word_size, 400 bool* gc_overhead_limit_was_exceeded) { 401 assert_heap_not_locked_and_not_at_safepoint(); 402 403 if (is_humongous(word_size)) { 404 return attempt_allocation_humongous(word_size); 405 } 406 size_t dummy = 0; 407 return attempt_allocation(word_size, word_size, &dummy); 408 } 409 410 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 411 ResourceMark rm; // For retrieving the thread names in log messages. 412 413 // Make sure you read the note in attempt_allocation_humongous(). 414 415 assert_heap_not_locked_and_not_at_safepoint(); 416 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 417 "be called for humongous allocation requests"); 418 419 // We should only get here after the first-level allocation attempt 420 // (attempt_allocation()) failed to allocate. 421 422 // We will loop until a) we manage to successfully perform the 423 // allocation or b) we successfully schedule a collection which 424 // fails to perform the allocation. b) is the only case when we'll 425 // return NULL. 426 HeapWord* result = NULL; 427 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 428 bool should_try_gc; 429 uint gc_count_before; 430 431 { 432 MutexLockerEx x(Heap_lock); 433 result = _allocator->attempt_allocation_locked(word_size); 434 if (result != NULL) { 435 return result; 436 } 437 438 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 439 // This is different to when only GCLocker::needs_gc() is set: try to avoid 440 // waiting because the GCLocker is active to not wait too long. 441 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) { 442 // No need for an ergo message here, can_expand_young_list() does this when 443 // it returns true. 444 result = _allocator->attempt_allocation_force(word_size); 445 if (result != NULL) { 446 return result; 447 } 448 } 449 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 450 // the GCLocker initiated GC has been performed and then retry. This includes 451 // the case when the GC Locker is not active but has not been performed. 452 should_try_gc = !GCLocker::needs_gc(); 453 // Read the GC count while still holding the Heap_lock. 454 gc_count_before = total_collections(); 455 } 456 457 if (should_try_gc) { 458 bool succeeded; 459 result = do_collection_pause(word_size, gc_count_before, &succeeded, 460 GCCause::_g1_inc_collection_pause); 461 if (result != NULL) { 462 assert(succeeded, "only way to get back a non-NULL result"); 463 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 464 Thread::current()->name(), p2i(result)); 465 return result; 466 } 467 468 if (succeeded) { 469 // We successfully scheduled a collection which failed to allocate. No 470 // point in trying to allocate further. We'll just return NULL. 471 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 472 SIZE_FORMAT " words", Thread::current()->name(), word_size); 473 return NULL; 474 } 475 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 476 Thread::current()->name(), word_size); 477 } else { 478 // Failed to schedule a collection. 479 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 480 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 481 SIZE_FORMAT " words", Thread::current()->name(), word_size); 482 return NULL; 483 } 484 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 485 // The GCLocker is either active or the GCLocker initiated 486 // GC has not yet been performed. Stall until it is and 487 // then retry the allocation. 488 GCLocker::stall_until_clear(); 489 gclocker_retry_count += 1; 490 } 491 492 // We can reach here if we were unsuccessful in scheduling a 493 // collection (because another thread beat us to it) or if we were 494 // stalled due to the GC locker. In either can we should retry the 495 // allocation attempt in case another thread successfully 496 // performed a collection and reclaimed enough space. We do the 497 // first attempt (without holding the Heap_lock) here and the 498 // follow-on attempt will be at the start of the next loop 499 // iteration (after taking the Heap_lock). 500 size_t dummy = 0; 501 result = _allocator->attempt_allocation(word_size, word_size, &dummy); 502 if (result != NULL) { 503 return result; 504 } 505 506 // Give a warning if we seem to be looping forever. 507 if ((QueuedAllocationWarningCount > 0) && 508 (try_count % QueuedAllocationWarningCount == 0)) { 509 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 510 Thread::current()->name(), try_count, word_size); 511 } 512 } 513 514 ShouldNotReachHere(); 515 return NULL; 516 } 517 518 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 519 assert_at_safepoint_on_vm_thread(); 520 if (_archive_allocator == NULL) { 521 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 522 } 523 } 524 525 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 526 // Allocations in archive regions cannot be of a size that would be considered 527 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 528 // may be different at archive-restore time. 529 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 530 } 531 532 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 533 assert_at_safepoint_on_vm_thread(); 534 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 535 if (is_archive_alloc_too_large(word_size)) { 536 return NULL; 537 } 538 return _archive_allocator->archive_mem_allocate(word_size); 539 } 540 541 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 542 size_t end_alignment_in_bytes) { 543 assert_at_safepoint_on_vm_thread(); 544 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 545 546 // Call complete_archive to do the real work, filling in the MemRegion 547 // array with the archive regions. 548 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 549 delete _archive_allocator; 550 _archive_allocator = NULL; 551 } 552 553 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 554 assert(ranges != NULL, "MemRegion array NULL"); 555 assert(count != 0, "No MemRegions provided"); 556 MemRegion reserved = _hrm.reserved(); 557 for (size_t i = 0; i < count; i++) { 558 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 559 return false; 560 } 561 } 562 return true; 563 } 564 565 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 566 size_t count, 567 bool open) { 568 assert(!is_init_completed(), "Expect to be called at JVM init time"); 569 assert(ranges != NULL, "MemRegion array NULL"); 570 assert(count != 0, "No MemRegions provided"); 571 MutexLockerEx x(Heap_lock); 572 573 MemRegion reserved = _hrm.reserved(); 574 HeapWord* prev_last_addr = NULL; 575 HeapRegion* prev_last_region = NULL; 576 577 // Temporarily disable pretouching of heap pages. This interface is used 578 // when mmap'ing archived heap data in, so pre-touching is wasted. 579 FlagSetting fs(AlwaysPreTouch, false); 580 581 // Enable archive object checking used by G1MarkSweep. We have to let it know 582 // about each archive range, so that objects in those ranges aren't marked. 583 G1ArchiveAllocator::enable_archive_object_check(); 584 585 // For each specified MemRegion range, allocate the corresponding G1 586 // regions and mark them as archive regions. We expect the ranges 587 // in ascending starting address order, without overlap. 588 for (size_t i = 0; i < count; i++) { 589 MemRegion curr_range = ranges[i]; 590 HeapWord* start_address = curr_range.start(); 591 size_t word_size = curr_range.word_size(); 592 HeapWord* last_address = curr_range.last(); 593 size_t commits = 0; 594 595 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 596 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 597 p2i(start_address), p2i(last_address)); 598 guarantee(start_address > prev_last_addr, 599 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 600 p2i(start_address), p2i(prev_last_addr)); 601 prev_last_addr = last_address; 602 603 // Check for ranges that start in the same G1 region in which the previous 604 // range ended, and adjust the start address so we don't try to allocate 605 // the same region again. If the current range is entirely within that 606 // region, skip it, just adjusting the recorded top. 607 HeapRegion* start_region = _hrm.addr_to_region(start_address); 608 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 609 start_address = start_region->end(); 610 if (start_address > last_address) { 611 increase_used(word_size * HeapWordSize); 612 start_region->set_top(last_address + 1); 613 continue; 614 } 615 start_region->set_top(start_address); 616 curr_range = MemRegion(start_address, last_address + 1); 617 start_region = _hrm.addr_to_region(start_address); 618 } 619 620 // Perform the actual region allocation, exiting if it fails. 621 // Then note how much new space we have allocated. 622 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) { 623 return false; 624 } 625 increase_used(word_size * HeapWordSize); 626 if (commits != 0) { 627 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 628 HeapRegion::GrainWords * HeapWordSize * commits); 629 630 } 631 632 // Mark each G1 region touched by the range as archive, add it to 633 // the old set, and set top. 634 HeapRegion* curr_region = _hrm.addr_to_region(start_address); 635 HeapRegion* last_region = _hrm.addr_to_region(last_address); 636 prev_last_region = last_region; 637 638 while (curr_region != NULL) { 639 assert(curr_region->is_empty() && !curr_region->is_pinned(), 640 "Region already in use (index %u)", curr_region->hrm_index()); 641 if (open) { 642 curr_region->set_open_archive(); 643 } else { 644 curr_region->set_closed_archive(); 645 } 646 _hr_printer.alloc(curr_region); 647 _archive_set.add(curr_region); 648 HeapWord* top; 649 HeapRegion* next_region; 650 if (curr_region != last_region) { 651 top = curr_region->end(); 652 next_region = _hrm.next_region_in_heap(curr_region); 653 } else { 654 top = last_address + 1; 655 next_region = NULL; 656 } 657 curr_region->set_top(top); 658 curr_region->set_first_dead(top); 659 curr_region->set_end_of_live(top); 660 curr_region = next_region; 661 } 662 663 // Notify mark-sweep of the archive 664 G1ArchiveAllocator::set_range_archive(curr_range, open); 665 } 666 return true; 667 } 668 669 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 670 assert(!is_init_completed(), "Expect to be called at JVM init time"); 671 assert(ranges != NULL, "MemRegion array NULL"); 672 assert(count != 0, "No MemRegions provided"); 673 MemRegion reserved = _hrm.reserved(); 674 HeapWord *prev_last_addr = NULL; 675 HeapRegion* prev_last_region = NULL; 676 677 // For each MemRegion, create filler objects, if needed, in the G1 regions 678 // that contain the address range. The address range actually within the 679 // MemRegion will not be modified. That is assumed to have been initialized 680 // elsewhere, probably via an mmap of archived heap data. 681 MutexLockerEx x(Heap_lock); 682 for (size_t i = 0; i < count; i++) { 683 HeapWord* start_address = ranges[i].start(); 684 HeapWord* last_address = ranges[i].last(); 685 686 assert(reserved.contains(start_address) && reserved.contains(last_address), 687 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 688 p2i(start_address), p2i(last_address)); 689 assert(start_address > prev_last_addr, 690 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 691 p2i(start_address), p2i(prev_last_addr)); 692 693 HeapRegion* start_region = _hrm.addr_to_region(start_address); 694 HeapRegion* last_region = _hrm.addr_to_region(last_address); 695 HeapWord* bottom_address = start_region->bottom(); 696 697 // Check for a range beginning in the same region in which the 698 // previous one ended. 699 if (start_region == prev_last_region) { 700 bottom_address = prev_last_addr + 1; 701 } 702 703 // Verify that the regions were all marked as archive regions by 704 // alloc_archive_regions. 705 HeapRegion* curr_region = start_region; 706 while (curr_region != NULL) { 707 guarantee(curr_region->is_archive(), 708 "Expected archive region at index %u", curr_region->hrm_index()); 709 if (curr_region != last_region) { 710 curr_region = _hrm.next_region_in_heap(curr_region); 711 } else { 712 curr_region = NULL; 713 } 714 } 715 716 prev_last_addr = last_address; 717 prev_last_region = last_region; 718 719 // Fill the memory below the allocated range with dummy object(s), 720 // if the region bottom does not match the range start, or if the previous 721 // range ended within the same G1 region, and there is a gap. 722 if (start_address != bottom_address) { 723 size_t fill_size = pointer_delta(start_address, bottom_address); 724 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 725 increase_used(fill_size * HeapWordSize); 726 } 727 } 728 } 729 730 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size, 731 size_t desired_word_size, 732 size_t* actual_word_size) { 733 assert_heap_not_locked_and_not_at_safepoint(); 734 assert(!is_humongous(desired_word_size), "attempt_allocation() should not " 735 "be called for humongous allocation requests"); 736 737 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size); 738 739 if (result == NULL) { 740 *actual_word_size = desired_word_size; 741 result = attempt_allocation_slow(desired_word_size); 742 } 743 744 assert_heap_not_locked(); 745 if (result != NULL) { 746 assert(*actual_word_size != 0, "Actual size must have been set here"); 747 dirty_young_block(result, *actual_word_size); 748 } else { 749 *actual_word_size = 0; 750 } 751 752 return result; 753 } 754 755 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 756 assert(!is_init_completed(), "Expect to be called at JVM init time"); 757 assert(ranges != NULL, "MemRegion array NULL"); 758 assert(count != 0, "No MemRegions provided"); 759 MemRegion reserved = _hrm.reserved(); 760 HeapWord* prev_last_addr = NULL; 761 HeapRegion* prev_last_region = NULL; 762 size_t size_used = 0; 763 size_t uncommitted_regions = 0; 764 765 // For each Memregion, free the G1 regions that constitute it, and 766 // notify mark-sweep that the range is no longer to be considered 'archive.' 767 MutexLockerEx x(Heap_lock); 768 for (size_t i = 0; i < count; i++) { 769 HeapWord* start_address = ranges[i].start(); 770 HeapWord* last_address = ranges[i].last(); 771 772 assert(reserved.contains(start_address) && reserved.contains(last_address), 773 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 774 p2i(start_address), p2i(last_address)); 775 assert(start_address > prev_last_addr, 776 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 777 p2i(start_address), p2i(prev_last_addr)); 778 size_used += ranges[i].byte_size(); 779 prev_last_addr = last_address; 780 781 HeapRegion* start_region = _hrm.addr_to_region(start_address); 782 HeapRegion* last_region = _hrm.addr_to_region(last_address); 783 784 // Check for ranges that start in the same G1 region in which the previous 785 // range ended, and adjust the start address so we don't try to free 786 // the same region again. If the current range is entirely within that 787 // region, skip it. 788 if (start_region == prev_last_region) { 789 start_address = start_region->end(); 790 if (start_address > last_address) { 791 continue; 792 } 793 start_region = _hrm.addr_to_region(start_address); 794 } 795 prev_last_region = last_region; 796 797 // After verifying that each region was marked as an archive region by 798 // alloc_archive_regions, set it free and empty and uncommit it. 799 HeapRegion* curr_region = start_region; 800 while (curr_region != NULL) { 801 guarantee(curr_region->is_archive(), 802 "Expected archive region at index %u", curr_region->hrm_index()); 803 uint curr_index = curr_region->hrm_index(); 804 _archive_set.remove(curr_region); 805 curr_region->set_free(); 806 curr_region->set_top(curr_region->bottom()); 807 if (curr_region != last_region) { 808 curr_region = _hrm.next_region_in_heap(curr_region); 809 } else { 810 curr_region = NULL; 811 } 812 _hrm.shrink_at(curr_index, 1); 813 uncommitted_regions++; 814 } 815 816 // Notify mark-sweep that this is no longer an archive range. 817 G1ArchiveAllocator::set_range_archive(ranges[i], false); 818 } 819 820 if (uncommitted_regions != 0) { 821 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 822 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 823 } 824 decrease_used(size_used); 825 } 826 827 oop G1CollectedHeap::materialize_archived_object(oop obj) { 828 assert(obj != NULL, "archived obj is NULL"); 829 assert(MetaspaceShared::is_archive_object(obj), "must be archived object"); 830 831 // Loading an archived object makes it strongly reachable. If it is 832 // loaded during concurrent marking, it must be enqueued to the SATB 833 // queue, shading the previously white object gray. 834 G1BarrierSet::enqueue(obj); 835 836 return obj; 837 } 838 839 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 840 ResourceMark rm; // For retrieving the thread names in log messages. 841 842 // The structure of this method has a lot of similarities to 843 // attempt_allocation_slow(). The reason these two were not merged 844 // into a single one is that such a method would require several "if 845 // allocation is not humongous do this, otherwise do that" 846 // conditional paths which would obscure its flow. In fact, an early 847 // version of this code did use a unified method which was harder to 848 // follow and, as a result, it had subtle bugs that were hard to 849 // track down. So keeping these two methods separate allows each to 850 // be more readable. It will be good to keep these two in sync as 851 // much as possible. 852 853 assert_heap_not_locked_and_not_at_safepoint(); 854 assert(is_humongous(word_size), "attempt_allocation_humongous() " 855 "should only be called for humongous allocations"); 856 857 // Humongous objects can exhaust the heap quickly, so we should check if we 858 // need to start a marking cycle at each humongous object allocation. We do 859 // the check before we do the actual allocation. The reason for doing it 860 // before the allocation is that we avoid having to keep track of the newly 861 // allocated memory while we do a GC. 862 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 863 word_size)) { 864 collect(GCCause::_g1_humongous_allocation); 865 } 866 867 // We will loop until a) we manage to successfully perform the 868 // allocation or b) we successfully schedule a collection which 869 // fails to perform the allocation. b) is the only case when we'll 870 // return NULL. 871 HeapWord* result = NULL; 872 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 873 bool should_try_gc; 874 uint gc_count_before; 875 876 877 { 878 MutexLockerEx x(Heap_lock); 879 880 // Given that humongous objects are not allocated in young 881 // regions, we'll first try to do the allocation without doing a 882 // collection hoping that there's enough space in the heap. 883 result = humongous_obj_allocate(word_size); 884 if (result != NULL) { 885 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 886 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 887 return result; 888 } 889 890 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 891 // the GCLocker initiated GC has been performed and then retry. This includes 892 // the case when the GC Locker is not active but has not been performed. 893 should_try_gc = !GCLocker::needs_gc(); 894 // Read the GC count while still holding the Heap_lock. 895 gc_count_before = total_collections(); 896 } 897 898 if (should_try_gc) { 899 bool succeeded; 900 result = do_collection_pause(word_size, gc_count_before, &succeeded, 901 GCCause::_g1_humongous_allocation); 902 if (result != NULL) { 903 assert(succeeded, "only way to get back a non-NULL result"); 904 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 905 Thread::current()->name(), p2i(result)); 906 return result; 907 } 908 909 if (succeeded) { 910 // We successfully scheduled a collection which failed to allocate. No 911 // point in trying to allocate further. We'll just return NULL. 912 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 913 SIZE_FORMAT " words", Thread::current()->name(), word_size); 914 return NULL; 915 } 916 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 917 Thread::current()->name(), word_size); 918 } else { 919 // Failed to schedule a collection. 920 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 921 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 922 SIZE_FORMAT " words", Thread::current()->name(), word_size); 923 return NULL; 924 } 925 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 926 // The GCLocker is either active or the GCLocker initiated 927 // GC has not yet been performed. Stall until it is and 928 // then retry the allocation. 929 GCLocker::stall_until_clear(); 930 gclocker_retry_count += 1; 931 } 932 933 934 // We can reach here if we were unsuccessful in scheduling a 935 // collection (because another thread beat us to it) or if we were 936 // stalled due to the GC locker. In either can we should retry the 937 // allocation attempt in case another thread successfully 938 // performed a collection and reclaimed enough space. 939 // Humongous object allocation always needs a lock, so we wait for the retry 940 // in the next iteration of the loop, unlike for the regular iteration case. 941 // Give a warning if we seem to be looping forever. 942 943 if ((QueuedAllocationWarningCount > 0) && 944 (try_count % QueuedAllocationWarningCount == 0)) { 945 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 946 Thread::current()->name(), try_count, word_size); 947 } 948 } 949 950 ShouldNotReachHere(); 951 return NULL; 952 } 953 954 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 955 bool expect_null_mutator_alloc_region) { 956 assert_at_safepoint_on_vm_thread(); 957 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 958 "the current alloc region was unexpectedly found to be non-NULL"); 959 960 if (!is_humongous(word_size)) { 961 return _allocator->attempt_allocation_locked(word_size); 962 } else { 963 HeapWord* result = humongous_obj_allocate(word_size); 964 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 965 collector_state()->set_initiate_conc_mark_if_possible(true); 966 } 967 return result; 968 } 969 970 ShouldNotReachHere(); 971 } 972 973 class PostCompactionPrinterClosure: public HeapRegionClosure { 974 private: 975 G1HRPrinter* _hr_printer; 976 public: 977 bool do_heap_region(HeapRegion* hr) { 978 assert(!hr->is_young(), "not expecting to find young regions"); 979 _hr_printer->post_compaction(hr); 980 return false; 981 } 982 983 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 984 : _hr_printer(hr_printer) { } 985 }; 986 987 void G1CollectedHeap::print_hrm_post_compaction() { 988 if (_hr_printer.is_active()) { 989 PostCompactionPrinterClosure cl(hr_printer()); 990 heap_region_iterate(&cl); 991 } 992 } 993 994 void G1CollectedHeap::abort_concurrent_cycle() { 995 // If we start the compaction before the CM threads finish 996 // scanning the root regions we might trip them over as we'll 997 // be moving objects / updating references. So let's wait until 998 // they are done. By telling them to abort, they should complete 999 // early. 1000 _cm->root_regions()->abort(); 1001 _cm->root_regions()->wait_until_scan_finished(); 1002 1003 // Disable discovery and empty the discovered lists 1004 // for the CM ref processor. 1005 _ref_processor_cm->disable_discovery(); 1006 _ref_processor_cm->abandon_partial_discovery(); 1007 _ref_processor_cm->verify_no_references_recorded(); 1008 1009 // Abandon current iterations of concurrent marking and concurrent 1010 // refinement, if any are in progress. 1011 concurrent_mark()->concurrent_cycle_abort(); 1012 } 1013 1014 void G1CollectedHeap::prepare_heap_for_full_collection() { 1015 // Make sure we'll choose a new allocation region afterwards. 1016 _allocator->release_mutator_alloc_region(); 1017 _allocator->abandon_gc_alloc_regions(); 1018 g1_rem_set()->cleanupHRRS(); 1019 1020 // We may have added regions to the current incremental collection 1021 // set between the last GC or pause and now. We need to clear the 1022 // incremental collection set and then start rebuilding it afresh 1023 // after this full GC. 1024 abandon_collection_set(collection_set()); 1025 1026 tear_down_region_sets(false /* free_list_only */); 1027 } 1028 1029 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1030 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1031 assert(used() == recalculate_used(), "Should be equal"); 1032 _verifier->verify_region_sets_optional(); 1033 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1034 _verifier->check_bitmaps("Full GC Start"); 1035 } 1036 1037 void G1CollectedHeap::prepare_heap_for_mutators() { 1038 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1039 ClassLoaderDataGraph::purge(); 1040 MetaspaceUtils::verify_metrics(); 1041 1042 // Prepare heap for normal collections. 1043 assert(num_free_regions() == 0, "we should not have added any free regions"); 1044 rebuild_region_sets(false /* free_list_only */); 1045 abort_refinement(); 1046 resize_if_necessary_after_full_collection(); 1047 1048 // Rebuild the strong code root lists for each region 1049 rebuild_strong_code_roots(); 1050 1051 // Start a new incremental collection set for the next pause 1052 start_new_collection_set(); 1053 1054 _allocator->init_mutator_alloc_region(); 1055 1056 // Post collection state updates. 1057 MetaspaceGC::compute_new_size(); 1058 } 1059 1060 void G1CollectedHeap::abort_refinement() { 1061 if (_hot_card_cache->use_cache()) { 1062 _hot_card_cache->reset_hot_cache(); 1063 } 1064 1065 // Discard all remembered set updates. 1066 G1BarrierSet::dirty_card_queue_set().abandon_logs(); 1067 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1068 } 1069 1070 void G1CollectedHeap::verify_after_full_collection() { 1071 _hrm.verify_optional(); 1072 _verifier->verify_region_sets_optional(); 1073 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1074 // Clear the previous marking bitmap, if needed for bitmap verification. 1075 // Note we cannot do this when we clear the next marking bitmap in 1076 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1077 // objects marked during a full GC against the previous bitmap. 1078 // But we need to clear it before calling check_bitmaps below since 1079 // the full GC has compacted objects and updated TAMS but not updated 1080 // the prev bitmap. 1081 if (G1VerifyBitmaps) { 1082 GCTraceTime(Debug, gc)("Clear Prev Bitmap for Verification"); 1083 _cm->clear_prev_bitmap(workers()); 1084 } 1085 // This call implicitly verifies that the next bitmap is clear after Full GC. 1086 _verifier->check_bitmaps("Full GC End"); 1087 1088 // At this point there should be no regions in the 1089 // entire heap tagged as young. 1090 assert(check_young_list_empty(), "young list should be empty at this point"); 1091 1092 // Note: since we've just done a full GC, concurrent 1093 // marking is no longer active. Therefore we need not 1094 // re-enable reference discovery for the CM ref processor. 1095 // That will be done at the start of the next marking cycle. 1096 // We also know that the STW processor should no longer 1097 // discover any new references. 1098 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1099 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1100 _ref_processor_stw->verify_no_references_recorded(); 1101 _ref_processor_cm->verify_no_references_recorded(); 1102 } 1103 1104 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1105 // Post collection logging. 1106 // We should do this after we potentially resize the heap so 1107 // that all the COMMIT / UNCOMMIT events are generated before 1108 // the compaction events. 1109 print_hrm_post_compaction(); 1110 heap_transition->print(); 1111 print_heap_after_gc(); 1112 print_heap_regions(); 1113 #ifdef TRACESPINNING 1114 ParallelTaskTerminator::print_termination_counts(); 1115 #endif 1116 } 1117 1118 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1119 bool clear_all_soft_refs) { 1120 assert_at_safepoint_on_vm_thread(); 1121 1122 if (GCLocker::check_active_before_gc()) { 1123 // Full GC was not completed. 1124 return false; 1125 } 1126 1127 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1128 soft_ref_policy()->should_clear_all_soft_refs(); 1129 1130 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs); 1131 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1132 1133 collector.prepare_collection(); 1134 collector.collect(); 1135 collector.complete_collection(); 1136 1137 // Full collection was successfully completed. 1138 return true; 1139 } 1140 1141 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1142 // Currently, there is no facility in the do_full_collection(bool) API to notify 1143 // the caller that the collection did not succeed (e.g., because it was locked 1144 // out by the GC locker). So, right now, we'll ignore the return value. 1145 bool dummy = do_full_collection(true, /* explicit_gc */ 1146 clear_all_soft_refs); 1147 } 1148 1149 void G1CollectedHeap::resize_if_necessary_after_full_collection() { 1150 // Capacity, free and used after the GC counted as full regions to 1151 // include the waste in the following calculations. 1152 const size_t capacity_after_gc = capacity(); 1153 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1154 1155 // This is enforced in arguments.cpp. 1156 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1157 "otherwise the code below doesn't make sense"); 1158 1159 // We don't have floating point command-line arguments 1160 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1161 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1162 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1163 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1164 1165 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1166 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1167 1168 // We have to be careful here as these two calculations can overflow 1169 // 32-bit size_t's. 1170 double used_after_gc_d = (double) used_after_gc; 1171 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1172 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1173 1174 // Let's make sure that they are both under the max heap size, which 1175 // by default will make them fit into a size_t. 1176 double desired_capacity_upper_bound = (double) max_heap_size; 1177 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1178 desired_capacity_upper_bound); 1179 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1180 desired_capacity_upper_bound); 1181 1182 // We can now safely turn them into size_t's. 1183 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1184 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1185 1186 // This assert only makes sense here, before we adjust them 1187 // with respect to the min and max heap size. 1188 assert(minimum_desired_capacity <= maximum_desired_capacity, 1189 "minimum_desired_capacity = " SIZE_FORMAT ", " 1190 "maximum_desired_capacity = " SIZE_FORMAT, 1191 minimum_desired_capacity, maximum_desired_capacity); 1192 1193 // Should not be greater than the heap max size. No need to adjust 1194 // it with respect to the heap min size as it's a lower bound (i.e., 1195 // we'll try to make the capacity larger than it, not smaller). 1196 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1197 // Should not be less than the heap min size. No need to adjust it 1198 // with respect to the heap max size as it's an upper bound (i.e., 1199 // we'll try to make the capacity smaller than it, not greater). 1200 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1201 1202 if (capacity_after_gc < minimum_desired_capacity) { 1203 // Don't expand unless it's significant 1204 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1205 1206 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). " 1207 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1208 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1209 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1210 1211 expand(expand_bytes, _workers); 1212 1213 // No expansion, now see if we want to shrink 1214 } else if (capacity_after_gc > maximum_desired_capacity) { 1215 // Capacity too large, compute shrinking size 1216 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1217 1218 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). " 1219 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1220 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1221 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1222 1223 shrink(shrink_bytes); 1224 } 1225 } 1226 1227 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1228 bool do_gc, 1229 bool clear_all_soft_refs, 1230 bool expect_null_mutator_alloc_region, 1231 bool* gc_succeeded) { 1232 *gc_succeeded = true; 1233 // Let's attempt the allocation first. 1234 HeapWord* result = 1235 attempt_allocation_at_safepoint(word_size, 1236 expect_null_mutator_alloc_region); 1237 if (result != NULL) { 1238 return result; 1239 } 1240 1241 // In a G1 heap, we're supposed to keep allocation from failing by 1242 // incremental pauses. Therefore, at least for now, we'll favor 1243 // expansion over collection. (This might change in the future if we can 1244 // do something smarter than full collection to satisfy a failed alloc.) 1245 result = expand_and_allocate(word_size); 1246 if (result != NULL) { 1247 return result; 1248 } 1249 1250 if (do_gc) { 1251 // Expansion didn't work, we'll try to do a Full GC. 1252 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1253 clear_all_soft_refs); 1254 } 1255 1256 return NULL; 1257 } 1258 1259 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1260 bool* succeeded) { 1261 assert_at_safepoint_on_vm_thread(); 1262 1263 // Attempts to allocate followed by Full GC. 1264 HeapWord* result = 1265 satisfy_failed_allocation_helper(word_size, 1266 true, /* do_gc */ 1267 false, /* clear_all_soft_refs */ 1268 false, /* expect_null_mutator_alloc_region */ 1269 succeeded); 1270 1271 if (result != NULL || !*succeeded) { 1272 return result; 1273 } 1274 1275 // Attempts to allocate followed by Full GC that will collect all soft references. 1276 result = satisfy_failed_allocation_helper(word_size, 1277 true, /* do_gc */ 1278 true, /* clear_all_soft_refs */ 1279 true, /* expect_null_mutator_alloc_region */ 1280 succeeded); 1281 1282 if (result != NULL || !*succeeded) { 1283 return result; 1284 } 1285 1286 // Attempts to allocate, no GC 1287 result = satisfy_failed_allocation_helper(word_size, 1288 false, /* do_gc */ 1289 false, /* clear_all_soft_refs */ 1290 true, /* expect_null_mutator_alloc_region */ 1291 succeeded); 1292 1293 if (result != NULL) { 1294 return result; 1295 } 1296 1297 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1298 "Flag should have been handled and cleared prior to this point"); 1299 1300 // What else? We might try synchronous finalization later. If the total 1301 // space available is large enough for the allocation, then a more 1302 // complete compaction phase than we've tried so far might be 1303 // appropriate. 1304 return NULL; 1305 } 1306 1307 // Attempting to expand the heap sufficiently 1308 // to support an allocation of the given "word_size". If 1309 // successful, perform the allocation and return the address of the 1310 // allocated block, or else "NULL". 1311 1312 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1313 assert_at_safepoint_on_vm_thread(); 1314 1315 _verifier->verify_region_sets_optional(); 1316 1317 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1318 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1319 word_size * HeapWordSize); 1320 1321 1322 if (expand(expand_bytes, _workers)) { 1323 _hrm.verify_optional(); 1324 _verifier->verify_region_sets_optional(); 1325 return attempt_allocation_at_safepoint(word_size, 1326 false /* expect_null_mutator_alloc_region */); 1327 } 1328 return NULL; 1329 } 1330 1331 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1332 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1333 aligned_expand_bytes = align_up(aligned_expand_bytes, 1334 HeapRegion::GrainBytes); 1335 1336 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1337 expand_bytes, aligned_expand_bytes); 1338 1339 if (is_maximal_no_gc()) { 1340 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1341 return false; 1342 } 1343 1344 double expand_heap_start_time_sec = os::elapsedTime(); 1345 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1346 assert(regions_to_expand > 0, "Must expand by at least one region"); 1347 1348 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers); 1349 if (expand_time_ms != NULL) { 1350 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1351 } 1352 1353 if (expanded_by > 0) { 1354 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1355 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1356 g1_policy()->record_new_heap_size(num_regions()); 1357 } else { 1358 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1359 1360 // The expansion of the virtual storage space was unsuccessful. 1361 // Let's see if it was because we ran out of swap. 1362 if (G1ExitOnExpansionFailure && 1363 _hrm.available() >= regions_to_expand) { 1364 // We had head room... 1365 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1366 } 1367 } 1368 return regions_to_expand > 0; 1369 } 1370 1371 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1372 size_t aligned_shrink_bytes = 1373 ReservedSpace::page_align_size_down(shrink_bytes); 1374 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1375 HeapRegion::GrainBytes); 1376 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1377 1378 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1379 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1380 1381 1382 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", 1383 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1384 if (num_regions_removed > 0) { 1385 g1_policy()->record_new_heap_size(num_regions()); 1386 } else { 1387 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1388 } 1389 } 1390 1391 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1392 _verifier->verify_region_sets_optional(); 1393 1394 // We should only reach here at the end of a Full GC which means we 1395 // should not not be holding to any GC alloc regions. The method 1396 // below will make sure of that and do any remaining clean up. 1397 _allocator->abandon_gc_alloc_regions(); 1398 1399 // Instead of tearing down / rebuilding the free lists here, we 1400 // could instead use the remove_all_pending() method on free_list to 1401 // remove only the ones that we need to remove. 1402 tear_down_region_sets(true /* free_list_only */); 1403 shrink_helper(shrink_bytes); 1404 rebuild_region_sets(true /* free_list_only */); 1405 1406 _hrm.verify_optional(); 1407 _verifier->verify_region_sets_optional(); 1408 } 1409 1410 class OldRegionSetChecker : public HeapRegionSetChecker { 1411 public: 1412 void check_mt_safety() { 1413 // Master Old Set MT safety protocol: 1414 // (a) If we're at a safepoint, operations on the master old set 1415 // should be invoked: 1416 // - by the VM thread (which will serialize them), or 1417 // - by the GC workers while holding the FreeList_lock, if we're 1418 // at a safepoint for an evacuation pause (this lock is taken 1419 // anyway when an GC alloc region is retired so that a new one 1420 // is allocated from the free list), or 1421 // - by the GC workers while holding the OldSets_lock, if we're at a 1422 // safepoint for a cleanup pause. 1423 // (b) If we're not at a safepoint, operations on the master old set 1424 // should be invoked while holding the Heap_lock. 1425 1426 if (SafepointSynchronize::is_at_safepoint()) { 1427 guarantee(Thread::current()->is_VM_thread() || 1428 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 1429 "master old set MT safety protocol at a safepoint"); 1430 } else { 1431 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 1432 } 1433 } 1434 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); } 1435 const char* get_description() { return "Old Regions"; } 1436 }; 1437 1438 class ArchiveRegionSetChecker : public HeapRegionSetChecker { 1439 public: 1440 void check_mt_safety() { 1441 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(), 1442 "May only change archive regions during initialization or safepoint."); 1443 } 1444 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); } 1445 const char* get_description() { return "Archive Regions"; } 1446 }; 1447 1448 class HumongousRegionSetChecker : public HeapRegionSetChecker { 1449 public: 1450 void check_mt_safety() { 1451 // Humongous Set MT safety protocol: 1452 // (a) If we're at a safepoint, operations on the master humongous 1453 // set should be invoked by either the VM thread (which will 1454 // serialize them) or by the GC workers while holding the 1455 // OldSets_lock. 1456 // (b) If we're not at a safepoint, operations on the master 1457 // humongous set should be invoked while holding the Heap_lock. 1458 1459 if (SafepointSynchronize::is_at_safepoint()) { 1460 guarantee(Thread::current()->is_VM_thread() || 1461 OldSets_lock->owned_by_self(), 1462 "master humongous set MT safety protocol at a safepoint"); 1463 } else { 1464 guarantee(Heap_lock->owned_by_self(), 1465 "master humongous set MT safety protocol outside a safepoint"); 1466 } 1467 } 1468 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); } 1469 const char* get_description() { return "Humongous Regions"; } 1470 }; 1471 1472 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) : 1473 CollectedHeap(), 1474 _young_gen_sampling_thread(NULL), 1475 _workers(NULL), 1476 _collector_policy(collector_policy), 1477 _card_table(NULL), 1478 _soft_ref_policy(), 1479 _old_set("Old Region Set", new OldRegionSetChecker()), 1480 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()), 1481 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()), 1482 _bot(NULL), 1483 _listener(), 1484 _hrm(), 1485 _allocator(NULL), 1486 _verifier(NULL), 1487 _summary_bytes_used(0), 1488 _archive_allocator(NULL), 1489 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1490 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1491 _expand_heap_after_alloc_failure(true), 1492 _g1mm(NULL), 1493 _humongous_reclaim_candidates(), 1494 _has_humongous_reclaim_candidates(false), 1495 _hr_printer(), 1496 _collector_state(), 1497 _old_marking_cycles_started(0), 1498 _old_marking_cycles_completed(0), 1499 _eden(), 1500 _survivor(), 1501 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1502 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1503 _g1_policy(new G1Policy(_gc_timer_stw)), 1504 _heap_sizing_policy(NULL), 1505 _collection_set(this, _g1_policy), 1506 _hot_card_cache(NULL), 1507 _g1_rem_set(NULL), 1508 _dirty_card_queue_set(false), 1509 _cm(NULL), 1510 _cm_thread(NULL), 1511 _cr(NULL), 1512 _task_queues(NULL), 1513 _evacuation_failed(false), 1514 _evacuation_failed_info_array(NULL), 1515 _preserved_marks_set(true /* in_c_heap */), 1516 #ifndef PRODUCT 1517 _evacuation_failure_alot_for_current_gc(false), 1518 _evacuation_failure_alot_gc_number(0), 1519 _evacuation_failure_alot_count(0), 1520 #endif 1521 _ref_processor_stw(NULL), 1522 _is_alive_closure_stw(this), 1523 _is_subject_to_discovery_stw(this), 1524 _ref_processor_cm(NULL), 1525 _is_alive_closure_cm(this), 1526 _is_subject_to_discovery_cm(this), 1527 _in_cset_fast_test() { 1528 1529 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1530 true /* are_GC_task_threads */, 1531 false /* are_ConcurrentGC_threads */); 1532 _workers->initialize_workers(); 1533 _verifier = new G1HeapVerifier(this); 1534 1535 _allocator = new G1Allocator(this); 1536 1537 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics()); 1538 1539 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1540 1541 // Override the default _filler_array_max_size so that no humongous filler 1542 // objects are created. 1543 _filler_array_max_size = _humongous_object_threshold_in_words; 1544 1545 uint n_queues = ParallelGCThreads; 1546 _task_queues = new RefToScanQueueSet(n_queues); 1547 1548 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1549 1550 for (uint i = 0; i < n_queues; i++) { 1551 RefToScanQueue* q = new RefToScanQueue(); 1552 q->initialize(); 1553 _task_queues->register_queue(i, q); 1554 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1555 } 1556 1557 // Initialize the G1EvacuationFailureALot counters and flags. 1558 NOT_PRODUCT(reset_evacuation_should_fail();) 1559 1560 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1561 } 1562 1563 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1564 size_t size, 1565 size_t translation_factor) { 1566 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1567 // Allocate a new reserved space, preferring to use large pages. 1568 ReservedSpace rs(size, preferred_page_size); 1569 G1RegionToSpaceMapper* result = 1570 G1RegionToSpaceMapper::create_mapper(rs, 1571 size, 1572 rs.alignment(), 1573 HeapRegion::GrainBytes, 1574 translation_factor, 1575 mtGC); 1576 1577 os::trace_page_sizes_for_requested_size(description, 1578 size, 1579 preferred_page_size, 1580 rs.alignment(), 1581 rs.base(), 1582 rs.size()); 1583 1584 return result; 1585 } 1586 1587 jint G1CollectedHeap::initialize_concurrent_refinement() { 1588 jint ecode = JNI_OK; 1589 _cr = G1ConcurrentRefine::create(&ecode); 1590 return ecode; 1591 } 1592 1593 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1594 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1595 if (_young_gen_sampling_thread->osthread() == NULL) { 1596 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1597 return JNI_ENOMEM; 1598 } 1599 return JNI_OK; 1600 } 1601 1602 jint G1CollectedHeap::initialize() { 1603 os::enable_vtime(); 1604 1605 // Necessary to satisfy locking discipline assertions. 1606 1607 MutexLocker x(Heap_lock); 1608 1609 // While there are no constraints in the GC code that HeapWordSize 1610 // be any particular value, there are multiple other areas in the 1611 // system which believe this to be true (e.g. oop->object_size in some 1612 // cases incorrectly returns the size in wordSize units rather than 1613 // HeapWordSize). 1614 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1615 1616 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1617 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1618 size_t heap_alignment = collector_policy()->heap_alignment(); 1619 1620 // Ensure that the sizes are properly aligned. 1621 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1622 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1623 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1624 1625 // Reserve the maximum. 1626 1627 // When compressed oops are enabled, the preferred heap base 1628 // is calculated by subtracting the requested size from the 1629 // 32Gb boundary and using the result as the base address for 1630 // heap reservation. If the requested size is not aligned to 1631 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1632 // into the ReservedHeapSpace constructor) then the actual 1633 // base of the reserved heap may end up differing from the 1634 // address that was requested (i.e. the preferred heap base). 1635 // If this happens then we could end up using a non-optimal 1636 // compressed oops mode. 1637 1638 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1639 heap_alignment); 1640 1641 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1642 1643 // Create the barrier set for the entire reserved region. 1644 G1CardTable* ct = new G1CardTable(reserved_region()); 1645 ct->initialize(); 1646 G1BarrierSet* bs = new G1BarrierSet(ct); 1647 bs->initialize(); 1648 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1649 BarrierSet::set_barrier_set(bs); 1650 _card_table = ct; 1651 1652 // Create the hot card cache. 1653 _hot_card_cache = new G1HotCardCache(this); 1654 1655 // Carve out the G1 part of the heap. 1656 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1657 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 1658 G1RegionToSpaceMapper* heap_storage = 1659 G1RegionToSpaceMapper::create_mapper(g1_rs, 1660 g1_rs.size(), 1661 page_size, 1662 HeapRegion::GrainBytes, 1663 1, 1664 mtJavaHeap); 1665 os::trace_page_sizes("Heap", 1666 collector_policy()->min_heap_byte_size(), 1667 max_byte_size, 1668 page_size, 1669 heap_rs.base(), 1670 heap_rs.size()); 1671 heap_storage->set_mapping_changed_listener(&_listener); 1672 1673 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1674 G1RegionToSpaceMapper* bot_storage = 1675 create_aux_memory_mapper("Block Offset Table", 1676 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1677 G1BlockOffsetTable::heap_map_factor()); 1678 1679 G1RegionToSpaceMapper* cardtable_storage = 1680 create_aux_memory_mapper("Card Table", 1681 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1682 G1CardTable::heap_map_factor()); 1683 1684 G1RegionToSpaceMapper* card_counts_storage = 1685 create_aux_memory_mapper("Card Counts Table", 1686 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1687 G1CardCounts::heap_map_factor()); 1688 1689 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1690 G1RegionToSpaceMapper* prev_bitmap_storage = 1691 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1692 G1RegionToSpaceMapper* next_bitmap_storage = 1693 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1694 1695 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1696 _card_table->initialize(cardtable_storage); 1697 // Do later initialization work for concurrent refinement. 1698 _hot_card_cache->initialize(card_counts_storage); 1699 1700 // 6843694 - ensure that the maximum region index can fit 1701 // in the remembered set structures. 1702 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1703 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1704 1705 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1706 // start within the first card. 1707 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1708 // Also create a G1 rem set. 1709 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1710 _g1_rem_set->initialize(max_capacity(), max_regions()); 1711 1712 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1713 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1714 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1715 "too many cards per region"); 1716 1717 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1718 1719 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1720 1721 { 1722 HeapWord* start = _hrm.reserved().start(); 1723 HeapWord* end = _hrm.reserved().end(); 1724 size_t granularity = HeapRegion::GrainBytes; 1725 1726 _in_cset_fast_test.initialize(start, end, granularity); 1727 _humongous_reclaim_candidates.initialize(start, end, granularity); 1728 } 1729 1730 // Create the G1ConcurrentMark data structure and thread. 1731 // (Must do this late, so that "max_regions" is defined.) 1732 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1733 if (_cm == NULL || !_cm->completed_initialization()) { 1734 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1735 return JNI_ENOMEM; 1736 } 1737 _cm_thread = _cm->cm_thread(); 1738 1739 // Now expand into the initial heap size. 1740 if (!expand(init_byte_size, _workers)) { 1741 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1742 return JNI_ENOMEM; 1743 } 1744 1745 // Perform any initialization actions delegated to the policy. 1746 g1_policy()->init(this, &_collection_set); 1747 1748 G1BarrierSet::satb_mark_queue_set().initialize(this, 1749 SATB_Q_CBL_mon, 1750 SATB_Q_FL_lock, 1751 G1SATBProcessCompletedThreshold, 1752 G1SATBBufferEnqueueingThresholdPercent, 1753 Shared_SATB_Q_lock); 1754 1755 jint ecode = initialize_concurrent_refinement(); 1756 if (ecode != JNI_OK) { 1757 return ecode; 1758 } 1759 1760 ecode = initialize_young_gen_sampling_thread(); 1761 if (ecode != JNI_OK) { 1762 return ecode; 1763 } 1764 1765 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1766 DirtyCardQ_FL_lock, 1767 (int)concurrent_refine()->yellow_zone(), 1768 (int)concurrent_refine()->red_zone(), 1769 Shared_DirtyCardQ_lock, 1770 NULL, // fl_owner 1771 true); // init_free_ids 1772 1773 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1774 DirtyCardQ_FL_lock, 1775 -1, // never trigger processing 1776 -1, // no limit on length 1777 Shared_DirtyCardQ_lock, 1778 &G1BarrierSet::dirty_card_queue_set()); 1779 1780 // Here we allocate the dummy HeapRegion that is required by the 1781 // G1AllocRegion class. 1782 HeapRegion* dummy_region = _hrm.get_dummy_region(); 1783 1784 // We'll re-use the same region whether the alloc region will 1785 // require BOT updates or not and, if it doesn't, then a non-young 1786 // region will complain that it cannot support allocations without 1787 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1788 dummy_region->set_eden(); 1789 // Make sure it's full. 1790 dummy_region->set_top(dummy_region->end()); 1791 G1AllocRegion::setup(this, dummy_region); 1792 1793 _allocator->init_mutator_alloc_region(); 1794 1795 // Do create of the monitoring and management support so that 1796 // values in the heap have been properly initialized. 1797 _g1mm = new G1MonitoringSupport(this); 1798 1799 G1StringDedup::initialize(); 1800 1801 _preserved_marks_set.init(ParallelGCThreads); 1802 1803 _collection_set.initialize(max_regions()); 1804 1805 return JNI_OK; 1806 } 1807 1808 void G1CollectedHeap::stop() { 1809 // Stop all concurrent threads. We do this to make sure these threads 1810 // do not continue to execute and access resources (e.g. logging) 1811 // that are destroyed during shutdown. 1812 _cr->stop(); 1813 _young_gen_sampling_thread->stop(); 1814 _cm_thread->stop(); 1815 if (G1StringDedup::is_enabled()) { 1816 G1StringDedup::stop(); 1817 } 1818 } 1819 1820 void G1CollectedHeap::safepoint_synchronize_begin() { 1821 SuspendibleThreadSet::synchronize(); 1822 } 1823 1824 void G1CollectedHeap::safepoint_synchronize_end() { 1825 SuspendibleThreadSet::desynchronize(); 1826 } 1827 1828 size_t G1CollectedHeap::conservative_max_heap_alignment() { 1829 return HeapRegion::max_region_size(); 1830 } 1831 1832 void G1CollectedHeap::post_initialize() { 1833 CollectedHeap::post_initialize(); 1834 ref_processing_init(); 1835 } 1836 1837 void G1CollectedHeap::ref_processing_init() { 1838 // Reference processing in G1 currently works as follows: 1839 // 1840 // * There are two reference processor instances. One is 1841 // used to record and process discovered references 1842 // during concurrent marking; the other is used to 1843 // record and process references during STW pauses 1844 // (both full and incremental). 1845 // * Both ref processors need to 'span' the entire heap as 1846 // the regions in the collection set may be dotted around. 1847 // 1848 // * For the concurrent marking ref processor: 1849 // * Reference discovery is enabled at initial marking. 1850 // * Reference discovery is disabled and the discovered 1851 // references processed etc during remarking. 1852 // * Reference discovery is MT (see below). 1853 // * Reference discovery requires a barrier (see below). 1854 // * Reference processing may or may not be MT 1855 // (depending on the value of ParallelRefProcEnabled 1856 // and ParallelGCThreads). 1857 // * A full GC disables reference discovery by the CM 1858 // ref processor and abandons any entries on it's 1859 // discovered lists. 1860 // 1861 // * For the STW processor: 1862 // * Non MT discovery is enabled at the start of a full GC. 1863 // * Processing and enqueueing during a full GC is non-MT. 1864 // * During a full GC, references are processed after marking. 1865 // 1866 // * Discovery (may or may not be MT) is enabled at the start 1867 // of an incremental evacuation pause. 1868 // * References are processed near the end of a STW evacuation pause. 1869 // * For both types of GC: 1870 // * Discovery is atomic - i.e. not concurrent. 1871 // * Reference discovery will not need a barrier. 1872 1873 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1874 1875 // Concurrent Mark ref processor 1876 _ref_processor_cm = 1877 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1878 mt_processing, // mt processing 1879 ParallelGCThreads, // degree of mt processing 1880 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1881 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1882 false, // Reference discovery is not atomic 1883 &_is_alive_closure_cm, // is alive closure 1884 true); // allow changes to number of processing threads 1885 1886 // STW ref processor 1887 _ref_processor_stw = 1888 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1889 mt_processing, // mt processing 1890 ParallelGCThreads, // degree of mt processing 1891 (ParallelGCThreads > 1), // mt discovery 1892 ParallelGCThreads, // degree of mt discovery 1893 true, // Reference discovery is atomic 1894 &_is_alive_closure_stw, // is alive closure 1895 true); // allow changes to number of processing threads 1896 } 1897 1898 CollectorPolicy* G1CollectedHeap::collector_policy() const { 1899 return _collector_policy; 1900 } 1901 1902 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1903 return &_soft_ref_policy; 1904 } 1905 1906 size_t G1CollectedHeap::capacity() const { 1907 return _hrm.length() * HeapRegion::GrainBytes; 1908 } 1909 1910 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1911 return _hrm.total_free_bytes(); 1912 } 1913 1914 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) { 1915 _hot_card_cache->drain(cl, worker_i); 1916 } 1917 1918 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) { 1919 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1920 size_t n_completed_buffers = 0; 1921 while (dcqs.apply_closure_during_gc(cl, worker_i)) { 1922 n_completed_buffers++; 1923 } 1924 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers); 1925 dcqs.clear_n_completed_buffers(); 1926 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 1927 } 1928 1929 // Computes the sum of the storage used by the various regions. 1930 size_t G1CollectedHeap::used() const { 1931 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1932 if (_archive_allocator != NULL) { 1933 result += _archive_allocator->used(); 1934 } 1935 return result; 1936 } 1937 1938 size_t G1CollectedHeap::used_unlocked() const { 1939 return _summary_bytes_used; 1940 } 1941 1942 class SumUsedClosure: public HeapRegionClosure { 1943 size_t _used; 1944 public: 1945 SumUsedClosure() : _used(0) {} 1946 bool do_heap_region(HeapRegion* r) { 1947 _used += r->used(); 1948 return false; 1949 } 1950 size_t result() { return _used; } 1951 }; 1952 1953 size_t G1CollectedHeap::recalculate_used() const { 1954 SumUsedClosure blk; 1955 heap_region_iterate(&blk); 1956 return blk.result(); 1957 } 1958 1959 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1960 switch (cause) { 1961 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1962 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1963 case GCCause::_wb_conc_mark: return true; 1964 default : return false; 1965 } 1966 } 1967 1968 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 1969 switch (cause) { 1970 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 1971 case GCCause::_g1_humongous_allocation: return true; 1972 default: return is_user_requested_concurrent_full_gc(cause); 1973 } 1974 } 1975 1976 #ifndef PRODUCT 1977 void G1CollectedHeap::allocate_dummy_regions() { 1978 // Let's fill up most of the region 1979 size_t word_size = HeapRegion::GrainWords - 1024; 1980 // And as a result the region we'll allocate will be humongous. 1981 guarantee(is_humongous(word_size), "sanity"); 1982 1983 // _filler_array_max_size is set to humongous object threshold 1984 // but temporarily change it to use CollectedHeap::fill_with_object(). 1985 SizeTFlagSetting fs(_filler_array_max_size, word_size); 1986 1987 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 1988 // Let's use the existing mechanism for the allocation 1989 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 1990 if (dummy_obj != NULL) { 1991 MemRegion mr(dummy_obj, word_size); 1992 CollectedHeap::fill_with_object(mr); 1993 } else { 1994 // If we can't allocate once, we probably cannot allocate 1995 // again. Let's get out of the loop. 1996 break; 1997 } 1998 } 1999 } 2000 #endif // !PRODUCT 2001 2002 void G1CollectedHeap::increment_old_marking_cycles_started() { 2003 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2004 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2005 "Wrong marking cycle count (started: %d, completed: %d)", 2006 _old_marking_cycles_started, _old_marking_cycles_completed); 2007 2008 _old_marking_cycles_started++; 2009 } 2010 2011 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2012 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2013 2014 // We assume that if concurrent == true, then the caller is a 2015 // concurrent thread that was joined the Suspendible Thread 2016 // Set. If there's ever a cheap way to check this, we should add an 2017 // assert here. 2018 2019 // Given that this method is called at the end of a Full GC or of a 2020 // concurrent cycle, and those can be nested (i.e., a Full GC can 2021 // interrupt a concurrent cycle), the number of full collections 2022 // completed should be either one (in the case where there was no 2023 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2024 // behind the number of full collections started. 2025 2026 // This is the case for the inner caller, i.e. a Full GC. 2027 assert(concurrent || 2028 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2029 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2030 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2031 "is inconsistent with _old_marking_cycles_completed = %u", 2032 _old_marking_cycles_started, _old_marking_cycles_completed); 2033 2034 // This is the case for the outer caller, i.e. the concurrent cycle. 2035 assert(!concurrent || 2036 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2037 "for outer caller (concurrent cycle): " 2038 "_old_marking_cycles_started = %u " 2039 "is inconsistent with _old_marking_cycles_completed = %u", 2040 _old_marking_cycles_started, _old_marking_cycles_completed); 2041 2042 _old_marking_cycles_completed += 1; 2043 2044 // We need to clear the "in_progress" flag in the CM thread before 2045 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2046 // is set) so that if a waiter requests another System.gc() it doesn't 2047 // incorrectly see that a marking cycle is still in progress. 2048 if (concurrent) { 2049 _cm_thread->set_idle(); 2050 } 2051 2052 // This notify_all() will ensure that a thread that called 2053 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2054 // and it's waiting for a full GC to finish will be woken up. It is 2055 // waiting in VM_G1CollectForAllocation::doit_epilogue(). 2056 FullGCCount_lock->notify_all(); 2057 } 2058 2059 void G1CollectedHeap::collect(GCCause::Cause cause) { 2060 assert_heap_not_locked(); 2061 2062 uint gc_count_before; 2063 uint old_marking_count_before; 2064 uint full_gc_count_before; 2065 bool retry_gc; 2066 2067 do { 2068 retry_gc = false; 2069 2070 { 2071 MutexLocker ml(Heap_lock); 2072 2073 // Read the GC count while holding the Heap_lock 2074 gc_count_before = total_collections(); 2075 full_gc_count_before = total_full_collections(); 2076 old_marking_count_before = _old_marking_cycles_started; 2077 } 2078 2079 if (should_do_concurrent_full_gc(cause)) { 2080 // Schedule an initial-mark evacuation pause that will start a 2081 // concurrent cycle. We're setting word_size to 0 which means that 2082 // we are not requesting a post-GC allocation. 2083 VM_G1CollectForAllocation op(0, /* word_size */ 2084 gc_count_before, 2085 cause, 2086 true, /* should_initiate_conc_mark */ 2087 g1_policy()->max_pause_time_ms()); 2088 VMThread::execute(&op); 2089 if (!op.pause_succeeded()) { 2090 if (old_marking_count_before == _old_marking_cycles_started) { 2091 retry_gc = op.should_retry_gc(); 2092 } else { 2093 // A Full GC happened while we were trying to schedule the 2094 // initial-mark GC. No point in starting a new cycle given 2095 // that the whole heap was collected anyway. 2096 } 2097 2098 if (retry_gc) { 2099 if (GCLocker::is_active_and_needs_gc()) { 2100 GCLocker::stall_until_clear(); 2101 } 2102 } 2103 } 2104 } else { 2105 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2106 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2107 2108 // Schedule a standard evacuation pause. We're setting word_size 2109 // to 0 which means that we are not requesting a post-GC allocation. 2110 VM_G1CollectForAllocation op(0, /* word_size */ 2111 gc_count_before, 2112 cause, 2113 false, /* should_initiate_conc_mark */ 2114 g1_policy()->max_pause_time_ms()); 2115 VMThread::execute(&op); 2116 } else { 2117 // Schedule a Full GC. 2118 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2119 VMThread::execute(&op); 2120 } 2121 } 2122 } while (retry_gc); 2123 } 2124 2125 bool G1CollectedHeap::is_in(const void* p) const { 2126 if (_hrm.reserved().contains(p)) { 2127 // Given that we know that p is in the reserved space, 2128 // heap_region_containing() should successfully 2129 // return the containing region. 2130 HeapRegion* hr = heap_region_containing(p); 2131 return hr->is_in(p); 2132 } else { 2133 return false; 2134 } 2135 } 2136 2137 #ifdef ASSERT 2138 bool G1CollectedHeap::is_in_exact(const void* p) const { 2139 bool contains = reserved_region().contains(p); 2140 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2141 if (contains && available) { 2142 return true; 2143 } else { 2144 return false; 2145 } 2146 } 2147 #endif 2148 2149 // Iteration functions. 2150 2151 // Iterates an ObjectClosure over all objects within a HeapRegion. 2152 2153 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2154 ObjectClosure* _cl; 2155 public: 2156 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2157 bool do_heap_region(HeapRegion* r) { 2158 if (!r->is_continues_humongous()) { 2159 r->object_iterate(_cl); 2160 } 2161 return false; 2162 } 2163 }; 2164 2165 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2166 IterateObjectClosureRegionClosure blk(cl); 2167 heap_region_iterate(&blk); 2168 } 2169 2170 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2171 _hrm.iterate(cl); 2172 } 2173 2174 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2175 HeapRegionClaimer *hrclaimer, 2176 uint worker_id) const { 2177 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2178 } 2179 2180 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2181 HeapRegionClaimer *hrclaimer) const { 2182 _hrm.par_iterate(cl, hrclaimer, 0); 2183 } 2184 2185 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2186 _collection_set.iterate(cl); 2187 } 2188 2189 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) { 2190 _collection_set.iterate_from(cl, worker_id, workers()->active_workers()); 2191 } 2192 2193 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2194 HeapRegion* hr = heap_region_containing(addr); 2195 return hr->block_start(addr); 2196 } 2197 2198 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2199 HeapRegion* hr = heap_region_containing(addr); 2200 return hr->block_size(addr); 2201 } 2202 2203 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2204 HeapRegion* hr = heap_region_containing(addr); 2205 return hr->block_is_obj(addr); 2206 } 2207 2208 bool G1CollectedHeap::supports_tlab_allocation() const { 2209 return true; 2210 } 2211 2212 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2213 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2214 } 2215 2216 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2217 return _eden.length() * HeapRegion::GrainBytes; 2218 } 2219 2220 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2221 // must be equal to the humongous object limit. 2222 size_t G1CollectedHeap::max_tlab_size() const { 2223 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2224 } 2225 2226 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2227 return _allocator->unsafe_max_tlab_alloc(); 2228 } 2229 2230 size_t G1CollectedHeap::max_capacity() const { 2231 return _hrm.reserved().byte_size(); 2232 } 2233 2234 jlong G1CollectedHeap::millis_since_last_gc() { 2235 // See the notes in GenCollectedHeap::millis_since_last_gc() 2236 // for more information about the implementation. 2237 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2238 _g1_policy->collection_pause_end_millis(); 2239 if (ret_val < 0) { 2240 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2241 ". returning zero instead.", ret_val); 2242 return 0; 2243 } 2244 return ret_val; 2245 } 2246 2247 void G1CollectedHeap::deduplicate_string(oop str) { 2248 assert(java_lang_String::is_instance(str), "invariant"); 2249 2250 if (G1StringDedup::is_enabled()) { 2251 G1StringDedup::deduplicate(str); 2252 } 2253 } 2254 2255 void G1CollectedHeap::prepare_for_verify() { 2256 _verifier->prepare_for_verify(); 2257 } 2258 2259 void G1CollectedHeap::verify(VerifyOption vo) { 2260 _verifier->verify(vo); 2261 } 2262 2263 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2264 return true; 2265 } 2266 2267 const char* const* G1CollectedHeap::concurrent_phases() const { 2268 return _cm_thread->concurrent_phases(); 2269 } 2270 2271 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2272 return _cm_thread->request_concurrent_phase(phase); 2273 } 2274 2275 class PrintRegionClosure: public HeapRegionClosure { 2276 outputStream* _st; 2277 public: 2278 PrintRegionClosure(outputStream* st) : _st(st) {} 2279 bool do_heap_region(HeapRegion* r) { 2280 r->print_on(_st); 2281 return false; 2282 } 2283 }; 2284 2285 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2286 const HeapRegion* hr, 2287 const VerifyOption vo) const { 2288 switch (vo) { 2289 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2290 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2291 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2292 default: ShouldNotReachHere(); 2293 } 2294 return false; // keep some compilers happy 2295 } 2296 2297 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2298 const VerifyOption vo) const { 2299 switch (vo) { 2300 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2301 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2302 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2303 default: ShouldNotReachHere(); 2304 } 2305 return false; // keep some compilers happy 2306 } 2307 2308 void G1CollectedHeap::print_heap_regions() const { 2309 LogTarget(Trace, gc, heap, region) lt; 2310 if (lt.is_enabled()) { 2311 LogStream ls(lt); 2312 print_regions_on(&ls); 2313 } 2314 } 2315 2316 void G1CollectedHeap::print_on(outputStream* st) const { 2317 st->print(" %-20s", "garbage-first heap"); 2318 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2319 capacity()/K, used_unlocked()/K); 2320 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2321 p2i(_hrm.reserved().start()), 2322 p2i(_hrm.reserved().end())); 2323 st->cr(); 2324 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2325 uint young_regions = young_regions_count(); 2326 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2327 (size_t) young_regions * HeapRegion::GrainBytes / K); 2328 uint survivor_regions = survivor_regions_count(); 2329 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2330 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2331 st->cr(); 2332 MetaspaceUtils::print_on(st); 2333 } 2334 2335 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2336 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2337 "HS=humongous(starts), HC=humongous(continues), " 2338 "CS=collection set, F=free, A=archive, " 2339 "TAMS=top-at-mark-start (previous, next)"); 2340 PrintRegionClosure blk(st); 2341 heap_region_iterate(&blk); 2342 } 2343 2344 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2345 print_on(st); 2346 2347 // Print the per-region information. 2348 print_regions_on(st); 2349 } 2350 2351 void G1CollectedHeap::print_on_error(outputStream* st) const { 2352 this->CollectedHeap::print_on_error(st); 2353 2354 if (_cm != NULL) { 2355 st->cr(); 2356 _cm->print_on_error(st); 2357 } 2358 } 2359 2360 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2361 workers()->print_worker_threads_on(st); 2362 _cm_thread->print_on(st); 2363 st->cr(); 2364 _cm->print_worker_threads_on(st); 2365 _cr->print_threads_on(st); 2366 _young_gen_sampling_thread->print_on(st); 2367 if (G1StringDedup::is_enabled()) { 2368 G1StringDedup::print_worker_threads_on(st); 2369 } 2370 } 2371 2372 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2373 workers()->threads_do(tc); 2374 tc->do_thread(_cm_thread); 2375 _cm->threads_do(tc); 2376 _cr->threads_do(tc); 2377 tc->do_thread(_young_gen_sampling_thread); 2378 if (G1StringDedup::is_enabled()) { 2379 G1StringDedup::threads_do(tc); 2380 } 2381 } 2382 2383 void G1CollectedHeap::print_tracing_info() const { 2384 g1_rem_set()->print_summary_info(); 2385 concurrent_mark()->print_summary_info(); 2386 } 2387 2388 #ifndef PRODUCT 2389 // Helpful for debugging RSet issues. 2390 2391 class PrintRSetsClosure : public HeapRegionClosure { 2392 private: 2393 const char* _msg; 2394 size_t _occupied_sum; 2395 2396 public: 2397 bool do_heap_region(HeapRegion* r) { 2398 HeapRegionRemSet* hrrs = r->rem_set(); 2399 size_t occupied = hrrs->occupied(); 2400 _occupied_sum += occupied; 2401 2402 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2403 if (occupied == 0) { 2404 tty->print_cr(" RSet is empty"); 2405 } else { 2406 hrrs->print(); 2407 } 2408 tty->print_cr("----------"); 2409 return false; 2410 } 2411 2412 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2413 tty->cr(); 2414 tty->print_cr("========================================"); 2415 tty->print_cr("%s", msg); 2416 tty->cr(); 2417 } 2418 2419 ~PrintRSetsClosure() { 2420 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2421 tty->print_cr("========================================"); 2422 tty->cr(); 2423 } 2424 }; 2425 2426 void G1CollectedHeap::print_cset_rsets() { 2427 PrintRSetsClosure cl("Printing CSet RSets"); 2428 collection_set_iterate(&cl); 2429 } 2430 2431 void G1CollectedHeap::print_all_rsets() { 2432 PrintRSetsClosure cl("Printing All RSets");; 2433 heap_region_iterate(&cl); 2434 } 2435 #endif // PRODUCT 2436 2437 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2438 2439 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes; 2440 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes; 2441 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2442 2443 size_t eden_capacity_bytes = 2444 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2445 2446 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2447 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2448 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2449 } 2450 2451 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2452 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2453 stats->unused(), stats->used(), stats->region_end_waste(), 2454 stats->regions_filled(), stats->direct_allocated(), 2455 stats->failure_used(), stats->failure_waste()); 2456 } 2457 2458 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2459 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2460 gc_tracer->report_gc_heap_summary(when, heap_summary); 2461 2462 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2463 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2464 } 2465 2466 G1CollectedHeap* G1CollectedHeap::heap() { 2467 CollectedHeap* heap = Universe::heap(); 2468 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2469 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2470 return (G1CollectedHeap*)heap; 2471 } 2472 2473 void G1CollectedHeap::gc_prologue(bool full) { 2474 // always_do_update_barrier = false; 2475 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2476 2477 // This summary needs to be printed before incrementing total collections. 2478 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2479 2480 // Update common counters. 2481 increment_total_collections(full /* full gc */); 2482 if (full) { 2483 increment_old_marking_cycles_started(); 2484 } 2485 2486 // Fill TLAB's and such 2487 double start = os::elapsedTime(); 2488 ensure_parsability(true); 2489 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2490 } 2491 2492 void G1CollectedHeap::gc_epilogue(bool full) { 2493 // Update common counters. 2494 if (full) { 2495 // Update the number of full collections that have been completed. 2496 increment_old_marking_cycles_completed(false /* concurrent */); 2497 } 2498 2499 // We are at the end of the GC. Total collections has already been increased. 2500 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2501 2502 // FIXME: what is this about? 2503 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2504 // is set. 2505 #if COMPILER2_OR_JVMCI 2506 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2507 #endif 2508 // always_do_update_barrier = true; 2509 2510 double start = os::elapsedTime(); 2511 resize_all_tlabs(); 2512 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2513 2514 MemoryService::track_memory_usage(); 2515 // We have just completed a GC. Update the soft reference 2516 // policy with the new heap occupancy 2517 Universe::update_heap_info_at_gc(); 2518 } 2519 2520 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2521 uint gc_count_before, 2522 bool* succeeded, 2523 GCCause::Cause gc_cause) { 2524 assert_heap_not_locked_and_not_at_safepoint(); 2525 VM_G1CollectForAllocation op(word_size, 2526 gc_count_before, 2527 gc_cause, 2528 false, /* should_initiate_conc_mark */ 2529 g1_policy()->max_pause_time_ms()); 2530 VMThread::execute(&op); 2531 2532 HeapWord* result = op.result(); 2533 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 2534 assert(result == NULL || ret_succeeded, 2535 "the result should be NULL if the VM did not succeed"); 2536 *succeeded = ret_succeeded; 2537 2538 assert_heap_not_locked(); 2539 return result; 2540 } 2541 2542 void G1CollectedHeap::do_concurrent_mark() { 2543 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 2544 if (!_cm_thread->in_progress()) { 2545 _cm_thread->set_started(); 2546 CGC_lock->notify(); 2547 } 2548 } 2549 2550 size_t G1CollectedHeap::pending_card_num() { 2551 size_t extra_cards = 0; 2552 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) { 2553 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr); 2554 extra_cards += dcq.size(); 2555 } 2556 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 2557 size_t buffer_size = dcqs.buffer_size(); 2558 size_t buffer_num = dcqs.completed_buffers_num(); 2559 2560 return buffer_size * buffer_num + extra_cards; 2561 } 2562 2563 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2564 // We don't nominate objects with many remembered set entries, on 2565 // the assumption that such objects are likely still live. 2566 HeapRegionRemSet* rem_set = r->rem_set(); 2567 2568 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2569 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2570 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2571 } 2572 2573 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 2574 private: 2575 size_t _total_humongous; 2576 size_t _candidate_humongous; 2577 2578 DirtyCardQueue _dcq; 2579 2580 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const { 2581 assert(region->is_starts_humongous(), "Must start a humongous object"); 2582 2583 oop obj = oop(region->bottom()); 2584 2585 // Dead objects cannot be eager reclaim candidates. Due to class 2586 // unloading it is unsafe to query their classes so we return early. 2587 if (g1h->is_obj_dead(obj, region)) { 2588 return false; 2589 } 2590 2591 // If we do not have a complete remembered set for the region, then we can 2592 // not be sure that we have all references to it. 2593 if (!region->rem_set()->is_complete()) { 2594 return false; 2595 } 2596 // Candidate selection must satisfy the following constraints 2597 // while concurrent marking is in progress: 2598 // 2599 // * In order to maintain SATB invariants, an object must not be 2600 // reclaimed if it was allocated before the start of marking and 2601 // has not had its references scanned. Such an object must have 2602 // its references (including type metadata) scanned to ensure no 2603 // live objects are missed by the marking process. Objects 2604 // allocated after the start of concurrent marking don't need to 2605 // be scanned. 2606 // 2607 // * An object must not be reclaimed if it is on the concurrent 2608 // mark stack. Objects allocated after the start of concurrent 2609 // marking are never pushed on the mark stack. 2610 // 2611 // Nominating only objects allocated after the start of concurrent 2612 // marking is sufficient to meet both constraints. This may miss 2613 // some objects that satisfy the constraints, but the marking data 2614 // structures don't support efficiently performing the needed 2615 // additional tests or scrubbing of the mark stack. 2616 // 2617 // However, we presently only nominate is_typeArray() objects. 2618 // A humongous object containing references induces remembered 2619 // set entries on other regions. In order to reclaim such an 2620 // object, those remembered sets would need to be cleaned up. 2621 // 2622 // We also treat is_typeArray() objects specially, allowing them 2623 // to be reclaimed even if allocated before the start of 2624 // concurrent mark. For this we rely on mark stack insertion to 2625 // exclude is_typeArray() objects, preventing reclaiming an object 2626 // that is in the mark stack. We also rely on the metadata for 2627 // such objects to be built-in and so ensured to be kept live. 2628 // Frequent allocation and drop of large binary blobs is an 2629 // important use case for eager reclaim, and this special handling 2630 // may reduce needed headroom. 2631 2632 return obj->is_typeArray() && 2633 g1h->is_potential_eager_reclaim_candidate(region); 2634 } 2635 2636 public: 2637 RegisterHumongousWithInCSetFastTestClosure() 2638 : _total_humongous(0), 2639 _candidate_humongous(0), 2640 _dcq(&G1BarrierSet::dirty_card_queue_set()) { 2641 } 2642 2643 virtual bool do_heap_region(HeapRegion* r) { 2644 if (!r->is_starts_humongous()) { 2645 return false; 2646 } 2647 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2648 2649 bool is_candidate = humongous_region_is_candidate(g1h, r); 2650 uint rindex = r->hrm_index(); 2651 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2652 if (is_candidate) { 2653 _candidate_humongous++; 2654 g1h->register_humongous_region_with_cset(rindex); 2655 // Is_candidate already filters out humongous object with large remembered sets. 2656 // If we have a humongous object with a few remembered sets, we simply flush these 2657 // remembered set entries into the DCQS. That will result in automatic 2658 // re-evaluation of their remembered set entries during the following evacuation 2659 // phase. 2660 if (!r->rem_set()->is_empty()) { 2661 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 2662 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 2663 G1CardTable* ct = g1h->card_table(); 2664 HeapRegionRemSetIterator hrrs(r->rem_set()); 2665 size_t card_index; 2666 while (hrrs.has_next(card_index)) { 2667 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index); 2668 // The remembered set might contain references to already freed 2669 // regions. Filter out such entries to avoid failing card table 2670 // verification. 2671 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) { 2672 if (*card_ptr != G1CardTable::dirty_card_val()) { 2673 *card_ptr = G1CardTable::dirty_card_val(); 2674 _dcq.enqueue(card_ptr); 2675 } 2676 } 2677 } 2678 assert(hrrs.n_yielded() == r->rem_set()->occupied(), 2679 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", 2680 hrrs.n_yielded(), r->rem_set()->occupied()); 2681 // We should only clear the card based remembered set here as we will not 2682 // implicitly rebuild anything else during eager reclaim. Note that at the moment 2683 // (and probably never) we do not enter this path if there are other kind of 2684 // remembered sets for this region. 2685 r->rem_set()->clear_locked(true /* only_cardset */); 2686 // Clear_locked() above sets the state to Empty. However we want to continue 2687 // collecting remembered set entries for humongous regions that were not 2688 // reclaimed. 2689 r->rem_set()->set_state_complete(); 2690 } 2691 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 2692 } 2693 _total_humongous++; 2694 2695 return false; 2696 } 2697 2698 size_t total_humongous() const { return _total_humongous; } 2699 size_t candidate_humongous() const { return _candidate_humongous; } 2700 2701 void flush_rem_set_entries() { _dcq.flush(); } 2702 }; 2703 2704 void G1CollectedHeap::register_humongous_regions_with_cset() { 2705 if (!G1EagerReclaimHumongousObjects) { 2706 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 2707 return; 2708 } 2709 double time = os::elapsed_counter(); 2710 2711 // Collect reclaim candidate information and register candidates with cset. 2712 RegisterHumongousWithInCSetFastTestClosure cl; 2713 heap_region_iterate(&cl); 2714 2715 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 2716 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 2717 cl.total_humongous(), 2718 cl.candidate_humongous()); 2719 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2720 2721 // Finally flush all remembered set entries to re-check into the global DCQS. 2722 cl.flush_rem_set_entries(); 2723 } 2724 2725 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2726 public: 2727 bool do_heap_region(HeapRegion* hr) { 2728 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2729 hr->verify_rem_set(); 2730 } 2731 return false; 2732 } 2733 }; 2734 2735 uint G1CollectedHeap::num_task_queues() const { 2736 return _task_queues->size(); 2737 } 2738 2739 #if TASKQUEUE_STATS 2740 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2741 st->print_raw_cr("GC Task Stats"); 2742 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2743 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2744 } 2745 2746 void G1CollectedHeap::print_taskqueue_stats() const { 2747 if (!log_is_enabled(Trace, gc, task, stats)) { 2748 return; 2749 } 2750 Log(gc, task, stats) log; 2751 ResourceMark rm; 2752 LogStream ls(log.trace()); 2753 outputStream* st = &ls; 2754 2755 print_taskqueue_stats_hdr(st); 2756 2757 TaskQueueStats totals; 2758 const uint n = num_task_queues(); 2759 for (uint i = 0; i < n; ++i) { 2760 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2761 totals += task_queue(i)->stats; 2762 } 2763 st->print_raw("tot "); totals.print(st); st->cr(); 2764 2765 DEBUG_ONLY(totals.verify()); 2766 } 2767 2768 void G1CollectedHeap::reset_taskqueue_stats() { 2769 const uint n = num_task_queues(); 2770 for (uint i = 0; i < n; ++i) { 2771 task_queue(i)->stats.reset(); 2772 } 2773 } 2774 #endif // TASKQUEUE_STATS 2775 2776 void G1CollectedHeap::wait_for_root_region_scanning() { 2777 double scan_wait_start = os::elapsedTime(); 2778 // We have to wait until the CM threads finish scanning the 2779 // root regions as it's the only way to ensure that all the 2780 // objects on them have been correctly scanned before we start 2781 // moving them during the GC. 2782 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2783 double wait_time_ms = 0.0; 2784 if (waited) { 2785 double scan_wait_end = os::elapsedTime(); 2786 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2787 } 2788 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2789 } 2790 2791 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2792 private: 2793 G1HRPrinter* _hr_printer; 2794 public: 2795 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2796 2797 virtual bool do_heap_region(HeapRegion* r) { 2798 _hr_printer->cset(r); 2799 return false; 2800 } 2801 }; 2802 2803 void G1CollectedHeap::start_new_collection_set() { 2804 collection_set()->start_incremental_building(); 2805 2806 clear_cset_fast_test(); 2807 2808 guarantee(_eden.length() == 0, "eden should have been cleared"); 2809 g1_policy()->transfer_survivors_to_cset(survivor()); 2810 } 2811 2812 bool 2813 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2814 assert_at_safepoint_on_vm_thread(); 2815 guarantee(!is_gc_active(), "collection is not reentrant"); 2816 2817 if (GCLocker::check_active_before_gc()) { 2818 return false; 2819 } 2820 2821 _gc_timer_stw->register_gc_start(); 2822 2823 GCIdMark gc_id_mark; 2824 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2825 2826 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2827 ResourceMark rm; 2828 2829 g1_policy()->note_gc_start(); 2830 2831 wait_for_root_region_scanning(); 2832 2833 print_heap_before_gc(); 2834 print_heap_regions(); 2835 trace_heap_before_gc(_gc_tracer_stw); 2836 2837 _verifier->verify_region_sets_optional(); 2838 _verifier->verify_dirty_young_regions(); 2839 2840 // We should not be doing initial mark unless the conc mark thread is running 2841 if (!_cm_thread->should_terminate()) { 2842 // This call will decide whether this pause is an initial-mark 2843 // pause. If it is, in_initial_mark_gc() will return true 2844 // for the duration of this pause. 2845 g1_policy()->decide_on_conc_mark_initiation(); 2846 } 2847 2848 // We do not allow initial-mark to be piggy-backed on a mixed GC. 2849 assert(!collector_state()->in_initial_mark_gc() || 2850 collector_state()->in_young_only_phase(), "sanity"); 2851 2852 // We also do not allow mixed GCs during marking. 2853 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 2854 2855 // Record whether this pause is an initial mark. When the current 2856 // thread has completed its logging output and it's safe to signal 2857 // the CM thread, the flag's value in the policy has been reset. 2858 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 2859 2860 // Inner scope for scope based logging, timers, and stats collection 2861 { 2862 EvacuationInfo evacuation_info; 2863 2864 if (collector_state()->in_initial_mark_gc()) { 2865 // We are about to start a marking cycle, so we increment the 2866 // full collection counter. 2867 increment_old_marking_cycles_started(); 2868 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2869 } 2870 2871 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 2872 2873 GCTraceCPUTime tcpu; 2874 2875 G1HeapVerifier::G1VerifyType verify_type; 2876 FormatBuffer<> gc_string("Pause Young "); 2877 if (collector_state()->in_initial_mark_gc()) { 2878 gc_string.append("(Concurrent Start)"); 2879 verify_type = G1HeapVerifier::G1VerifyConcurrentStart; 2880 } else if (collector_state()->in_young_only_phase()) { 2881 if (collector_state()->in_young_gc_before_mixed()) { 2882 gc_string.append("(Prepare Mixed)"); 2883 } else { 2884 gc_string.append("(Normal)"); 2885 } 2886 verify_type = G1HeapVerifier::G1VerifyYoungNormal; 2887 } else { 2888 gc_string.append("(Mixed)"); 2889 verify_type = G1HeapVerifier::G1VerifyMixed; 2890 } 2891 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true); 2892 2893 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 2894 workers()->active_workers(), 2895 Threads::number_of_non_daemon_threads()); 2896 active_workers = workers()->update_active_workers(active_workers); 2897 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 2898 2899 G1MonitoringScope ms(g1mm(), 2900 false /* full_gc */, 2901 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 2902 2903 G1HeapTransition heap_transition(this); 2904 size_t heap_used_bytes_before_gc = used(); 2905 2906 // Don't dynamically change the number of GC threads this early. A value of 2907 // 0 is used to indicate serial work. When parallel work is done, 2908 // it will be set. 2909 2910 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 2911 IsGCActiveMark x; 2912 2913 gc_prologue(false); 2914 2915 if (VerifyRememberedSets) { 2916 log_info(gc, verify)("[Verifying RemSets before GC]"); 2917 VerifyRegionRemSetClosure v_cl; 2918 heap_region_iterate(&v_cl); 2919 } 2920 2921 _verifier->verify_before_gc(verify_type); 2922 2923 _verifier->check_bitmaps("GC Start"); 2924 2925 #if COMPILER2_OR_JVMCI 2926 DerivedPointerTable::clear(); 2927 #endif 2928 2929 // Please see comment in g1CollectedHeap.hpp and 2930 // G1CollectedHeap::ref_processing_init() to see how 2931 // reference processing currently works in G1. 2932 2933 // Enable discovery in the STW reference processor 2934 _ref_processor_stw->enable_discovery(); 2935 2936 { 2937 // We want to temporarily turn off discovery by the 2938 // CM ref processor, if necessary, and turn it back on 2939 // on again later if we do. Using a scoped 2940 // NoRefDiscovery object will do this. 2941 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 2942 2943 // Forget the current alloc region (we might even choose it to be part 2944 // of the collection set!). 2945 _allocator->release_mutator_alloc_region(); 2946 2947 // This timing is only used by the ergonomics to handle our pause target. 2948 // It is unclear why this should not include the full pause. We will 2949 // investigate this in CR 7178365. 2950 // 2951 // Preserving the old comment here if that helps the investigation: 2952 // 2953 // The elapsed time induced by the start time below deliberately elides 2954 // the possible verification above. 2955 double sample_start_time_sec = os::elapsedTime(); 2956 2957 g1_policy()->record_collection_pause_start(sample_start_time_sec); 2958 2959 if (collector_state()->in_initial_mark_gc()) { 2960 concurrent_mark()->pre_initial_mark(); 2961 } 2962 2963 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor); 2964 2965 evacuation_info.set_collectionset_regions(collection_set()->region_length()); 2966 2967 // Make sure the remembered sets are up to date. This needs to be 2968 // done before register_humongous_regions_with_cset(), because the 2969 // remembered sets are used there to choose eager reclaim candidates. 2970 // If the remembered sets are not up to date we might miss some 2971 // entries that need to be handled. 2972 g1_rem_set()->cleanupHRRS(); 2973 2974 register_humongous_regions_with_cset(); 2975 2976 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table."); 2977 2978 // We call this after finalize_cset() to 2979 // ensure that the CSet has been finalized. 2980 _cm->verify_no_cset_oops(); 2981 2982 if (_hr_printer.is_active()) { 2983 G1PrintCollectionSetClosure cl(&_hr_printer); 2984 _collection_set.iterate(&cl); 2985 } 2986 2987 // Initialize the GC alloc regions. 2988 _allocator->init_gc_alloc_regions(evacuation_info); 2989 2990 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length()); 2991 pre_evacuate_collection_set(); 2992 2993 // Actually do the work... 2994 evacuate_collection_set(&per_thread_states); 2995 2996 post_evacuate_collection_set(evacuation_info, &per_thread_states); 2997 2998 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 2999 free_collection_set(&_collection_set, evacuation_info, surviving_young_words); 3000 3001 eagerly_reclaim_humongous_regions(); 3002 3003 record_obj_copy_mem_stats(); 3004 _survivor_evac_stats.adjust_desired_plab_sz(); 3005 _old_evac_stats.adjust_desired_plab_sz(); 3006 3007 double start = os::elapsedTime(); 3008 start_new_collection_set(); 3009 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 3010 3011 if (evacuation_failed()) { 3012 double recalculate_used_start = os::elapsedTime(); 3013 set_used(recalculate_used()); 3014 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 3015 3016 if (_archive_allocator != NULL) { 3017 _archive_allocator->clear_used(); 3018 } 3019 for (uint i = 0; i < ParallelGCThreads; i++) { 3020 if (_evacuation_failed_info_array[i].has_failed()) { 3021 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3022 } 3023 } 3024 } else { 3025 // The "used" of the the collection set have already been subtracted 3026 // when they were freed. Add in the bytes evacuated. 3027 increase_used(g1_policy()->bytes_copied_during_gc()); 3028 } 3029 3030 if (collector_state()->in_initial_mark_gc()) { 3031 // We have to do this before we notify the CM threads that 3032 // they can start working to make sure that all the 3033 // appropriate initialization is done on the CM object. 3034 concurrent_mark()->post_initial_mark(); 3035 // Note that we don't actually trigger the CM thread at 3036 // this point. We do that later when we're sure that 3037 // the current thread has completed its logging output. 3038 } 3039 3040 allocate_dummy_regions(); 3041 3042 _allocator->init_mutator_alloc_region(); 3043 3044 { 3045 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 3046 if (expand_bytes > 0) { 3047 size_t bytes_before = capacity(); 3048 // No need for an ergo logging here, 3049 // expansion_amount() does this when it returns a value > 0. 3050 double expand_ms; 3051 if (!expand(expand_bytes, _workers, &expand_ms)) { 3052 // We failed to expand the heap. Cannot do anything about it. 3053 } 3054 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 3055 } 3056 } 3057 3058 // We redo the verification but now wrt to the new CSet which 3059 // has just got initialized after the previous CSet was freed. 3060 _cm->verify_no_cset_oops(); 3061 3062 // This timing is only used by the ergonomics to handle our pause target. 3063 // It is unclear why this should not include the full pause. We will 3064 // investigate this in CR 7178365. 3065 double sample_end_time_sec = os::elapsedTime(); 3066 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3067 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards); 3068 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc); 3069 3070 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3071 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 3072 3073 if (VerifyRememberedSets) { 3074 log_info(gc, verify)("[Verifying RemSets after GC]"); 3075 VerifyRegionRemSetClosure v_cl; 3076 heap_region_iterate(&v_cl); 3077 } 3078 3079 _verifier->verify_after_gc(verify_type); 3080 _verifier->check_bitmaps("GC End"); 3081 3082 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 3083 _ref_processor_stw->verify_no_references_recorded(); 3084 3085 // CM reference discovery will be re-enabled if necessary. 3086 } 3087 3088 #ifdef TRACESPINNING 3089 ParallelTaskTerminator::print_termination_counts(); 3090 #endif 3091 3092 gc_epilogue(false); 3093 } 3094 3095 // Print the remainder of the GC log output. 3096 if (evacuation_failed()) { 3097 log_info(gc)("To-space exhausted"); 3098 } 3099 3100 g1_policy()->print_phases(); 3101 heap_transition.print(); 3102 3103 // It is not yet to safe to tell the concurrent mark to 3104 // start as we have some optional output below. We don't want the 3105 // output from the concurrent mark thread interfering with this 3106 // logging output either. 3107 3108 _hrm.verify_optional(); 3109 _verifier->verify_region_sets_optional(); 3110 3111 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3112 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3113 3114 print_heap_after_gc(); 3115 print_heap_regions(); 3116 trace_heap_after_gc(_gc_tracer_stw); 3117 3118 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3119 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3120 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3121 // before any GC notifications are raised. 3122 g1mm()->update_sizes(); 3123 3124 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3125 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 3126 _gc_timer_stw->register_gc_end(); 3127 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3128 } 3129 // It should now be safe to tell the concurrent mark thread to start 3130 // without its logging output interfering with the logging output 3131 // that came from the pause. 3132 3133 if (should_start_conc_mark) { 3134 // CAUTION: after the doConcurrentMark() call below, 3135 // the concurrent marking thread(s) could be running 3136 // concurrently with us. Make sure that anything after 3137 // this point does not assume that we are the only GC thread 3138 // running. Note: of course, the actual marking work will 3139 // not start until the safepoint itself is released in 3140 // SuspendibleThreadSet::desynchronize(). 3141 do_concurrent_mark(); 3142 } 3143 3144 return true; 3145 } 3146 3147 void G1CollectedHeap::remove_self_forwarding_pointers() { 3148 G1ParRemoveSelfForwardPtrsTask rsfp_task; 3149 workers()->run_task(&rsfp_task); 3150 } 3151 3152 void G1CollectedHeap::restore_after_evac_failure() { 3153 double remove_self_forwards_start = os::elapsedTime(); 3154 3155 remove_self_forwarding_pointers(); 3156 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3157 _preserved_marks_set.restore(&task_executor); 3158 3159 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3160 } 3161 3162 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 3163 if (!_evacuation_failed) { 3164 _evacuation_failed = true; 3165 } 3166 3167 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3168 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3169 } 3170 3171 bool G1ParEvacuateFollowersClosure::offer_termination() { 3172 JFR_ONLY(EventGCPhaseParallel event;) 3173 G1ParScanThreadState* const pss = par_scan_state(); 3174 start_term_time(); 3175 const bool res = terminator()->offer_termination(); 3176 end_term_time(); 3177 JFR_ONLY(event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));) 3178 return res; 3179 } 3180 3181 void G1ParEvacuateFollowersClosure::do_void() { 3182 JFR_ONLY(EventGCPhaseParallel event;) 3183 G1ParScanThreadState* const pss = par_scan_state(); 3184 pss->trim_queue(); 3185 JFR_ONLY(event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy));) 3186 do { 3187 JFR_ONLY(EventGCPhaseParallel event;) 3188 pss->steal_and_trim_queue(queues()); 3189 JFR_ONLY(event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy));) 3190 } while (!offer_termination()); 3191 } 3192 3193 class G1ParTask : public AbstractGangTask { 3194 protected: 3195 G1CollectedHeap* _g1h; 3196 G1ParScanThreadStateSet* _pss; 3197 RefToScanQueueSet* _queues; 3198 G1RootProcessor* _root_processor; 3199 ParallelTaskTerminator _terminator; 3200 uint _n_workers; 3201 3202 public: 3203 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 3204 : AbstractGangTask("G1 collection"), 3205 _g1h(g1h), 3206 _pss(per_thread_states), 3207 _queues(task_queues), 3208 _root_processor(root_processor), 3209 _terminator(n_workers, _queues), 3210 _n_workers(n_workers) 3211 {} 3212 3213 void work(uint worker_id) { 3214 if (worker_id >= _n_workers) return; // no work needed this round 3215 3216 double start_sec = os::elapsedTime(); 3217 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 3218 3219 { 3220 ResourceMark rm; 3221 HandleMark hm; 3222 3223 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 3224 3225 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3226 pss->set_ref_discoverer(rp); 3227 3228 double start_strong_roots_sec = os::elapsedTime(); 3229 3230 _root_processor->evacuate_roots(pss, worker_id); 3231 3232 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid 3233 // treating the nmethods visited to act as roots for concurrent marking. 3234 // We only want to make sure that the oops in the nmethods are adjusted with regard to the 3235 // objects copied by the current evacuation. 3236 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id); 3237 3238 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 3239 3240 double term_sec = 0.0; 3241 size_t evac_term_attempts = 0; 3242 { 3243 double start = os::elapsedTime(); 3244 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator); 3245 evac.do_void(); 3246 3247 evac_term_attempts = evac.term_attempts(); 3248 term_sec = evac.term_time(); 3249 double elapsed_sec = os::elapsedTime() - start; 3250 3251 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times(); 3252 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 3253 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 3254 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 3255 } 3256 3257 assert(pss->queue_is_empty(), "should be empty"); 3258 3259 if (log_is_enabled(Debug, gc, task, stats)) { 3260 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3261 size_t lab_waste; 3262 size_t lab_undo_waste; 3263 pss->waste(lab_waste, lab_undo_waste); 3264 _g1h->print_termination_stats(worker_id, 3265 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 3266 strong_roots_sec * 1000.0, /* strong roots time */ 3267 term_sec * 1000.0, /* evac term time */ 3268 evac_term_attempts, /* evac term attempts */ 3269 lab_waste, /* alloc buffer waste */ 3270 lab_undo_waste /* undo waste */ 3271 ); 3272 } 3273 3274 // Close the inner scope so that the ResourceMark and HandleMark 3275 // destructors are executed here and are included as part of the 3276 // "GC Worker Time". 3277 } 3278 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 3279 } 3280 }; 3281 3282 void G1CollectedHeap::print_termination_stats_hdr() { 3283 log_debug(gc, task, stats)("GC Termination Stats"); 3284 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 3285 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo"); 3286 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 3287 } 3288 3289 void G1CollectedHeap::print_termination_stats(uint worker_id, 3290 double elapsed_ms, 3291 double strong_roots_ms, 3292 double term_ms, 3293 size_t term_attempts, 3294 size_t alloc_buffer_waste, 3295 size_t undo_waste) const { 3296 log_debug(gc, task, stats) 3297 ("%3d %9.2f %9.2f %6.2f " 3298 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 3299 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 3300 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 3301 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 3302 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 3303 alloc_buffer_waste * HeapWordSize / K, 3304 undo_waste * HeapWordSize / K); 3305 } 3306 3307 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3308 bool class_unloading_occurred) { 3309 uint n_workers = workers()->active_workers(); 3310 3311 G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false); 3312 ParallelCleaningTask g1_unlink_task(is_alive, &dedup_closure, n_workers, class_unloading_occurred); 3313 workers()->run_task(&g1_unlink_task); 3314 } 3315 3316 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive, 3317 bool process_strings, 3318 bool process_string_dedup) { 3319 if (!process_strings && !process_string_dedup) { 3320 // Nothing to clean. 3321 return; 3322 } 3323 3324 G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false); 3325 StringCleaningTask g1_unlink_task(is_alive, process_string_dedup ? &dedup_closure : NULL, process_strings); 3326 workers()->run_task(&g1_unlink_task); 3327 } 3328 3329 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3330 private: 3331 DirtyCardQueueSet* _queue; 3332 G1CollectedHeap* _g1h; 3333 public: 3334 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 3335 _queue(queue), _g1h(g1h) { } 3336 3337 virtual void work(uint worker_id) { 3338 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 3339 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 3340 3341 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3342 _queue->par_apply_closure_to_all_completed_buffers(&cl); 3343 3344 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3345 } 3346 }; 3347 3348 void G1CollectedHeap::redirty_logged_cards() { 3349 double redirty_logged_cards_start = os::elapsedTime(); 3350 3351 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 3352 dirty_card_queue_set().reset_for_par_iteration(); 3353 workers()->run_task(&redirty_task); 3354 3355 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3356 dcq.merge_bufferlists(&dirty_card_queue_set()); 3357 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 3358 3359 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3360 } 3361 3362 // Weak Reference Processing support 3363 3364 bool G1STWIsAliveClosure::do_object_b(oop p) { 3365 // An object is reachable if it is outside the collection set, 3366 // or is inside and copied. 3367 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3368 } 3369 3370 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3371 assert(obj != NULL, "must not be NULL"); 3372 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3373 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3374 // may falsely indicate that this is not the case here: however the collection set only 3375 // contains old regions when concurrent mark is not running. 3376 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3377 } 3378 3379 // Non Copying Keep Alive closure 3380 class G1KeepAliveClosure: public OopClosure { 3381 G1CollectedHeap*_g1h; 3382 public: 3383 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3384 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3385 void do_oop(oop* p) { 3386 oop obj = *p; 3387 assert(obj != NULL, "the caller should have filtered out NULL values"); 3388 3389 const InCSetState cset_state =_g1h->in_cset_state(obj); 3390 if (!cset_state.is_in_cset_or_humongous()) { 3391 return; 3392 } 3393 if (cset_state.is_in_cset()) { 3394 assert( obj->is_forwarded(), "invariant" ); 3395 *p = obj->forwardee(); 3396 } else { 3397 assert(!obj->is_forwarded(), "invariant" ); 3398 assert(cset_state.is_humongous(), 3399 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 3400 _g1h->set_humongous_is_live(obj); 3401 } 3402 } 3403 }; 3404 3405 // Copying Keep Alive closure - can be called from both 3406 // serial and parallel code as long as different worker 3407 // threads utilize different G1ParScanThreadState instances 3408 // and different queues. 3409 3410 class G1CopyingKeepAliveClosure: public OopClosure { 3411 G1CollectedHeap* _g1h; 3412 G1ParScanThreadState* _par_scan_state; 3413 3414 public: 3415 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3416 G1ParScanThreadState* pss): 3417 _g1h(g1h), 3418 _par_scan_state(pss) 3419 {} 3420 3421 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3422 virtual void do_oop( oop* p) { do_oop_work(p); } 3423 3424 template <class T> void do_oop_work(T* p) { 3425 oop obj = RawAccess<>::oop_load(p); 3426 3427 if (_g1h->is_in_cset_or_humongous(obj)) { 3428 // If the referent object has been forwarded (either copied 3429 // to a new location or to itself in the event of an 3430 // evacuation failure) then we need to update the reference 3431 // field and, if both reference and referent are in the G1 3432 // heap, update the RSet for the referent. 3433 // 3434 // If the referent has not been forwarded then we have to keep 3435 // it alive by policy. Therefore we have copy the referent. 3436 // 3437 // When the queue is drained (after each phase of reference processing) 3438 // the object and it's followers will be copied, the reference field set 3439 // to point to the new location, and the RSet updated. 3440 _par_scan_state->push_on_queue(p); 3441 } 3442 } 3443 }; 3444 3445 // Serial drain queue closure. Called as the 'complete_gc' 3446 // closure for each discovered list in some of the 3447 // reference processing phases. 3448 3449 class G1STWDrainQueueClosure: public VoidClosure { 3450 protected: 3451 G1CollectedHeap* _g1h; 3452 G1ParScanThreadState* _par_scan_state; 3453 3454 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3455 3456 public: 3457 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3458 _g1h(g1h), 3459 _par_scan_state(pss) 3460 { } 3461 3462 void do_void() { 3463 G1ParScanThreadState* const pss = par_scan_state(); 3464 pss->trim_queue(); 3465 } 3466 }; 3467 3468 // Parallel Reference Processing closures 3469 3470 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3471 // processing during G1 evacuation pauses. 3472 3473 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3474 private: 3475 G1CollectedHeap* _g1h; 3476 G1ParScanThreadStateSet* _pss; 3477 RefToScanQueueSet* _queues; 3478 WorkGang* _workers; 3479 3480 public: 3481 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3482 G1ParScanThreadStateSet* per_thread_states, 3483 WorkGang* workers, 3484 RefToScanQueueSet *task_queues) : 3485 _g1h(g1h), 3486 _pss(per_thread_states), 3487 _queues(task_queues), 3488 _workers(workers) 3489 { 3490 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3491 } 3492 3493 // Executes the given task using concurrent marking worker threads. 3494 virtual void execute(ProcessTask& task, uint ergo_workers); 3495 }; 3496 3497 // Gang task for possibly parallel reference processing 3498 3499 class G1STWRefProcTaskProxy: public AbstractGangTask { 3500 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3501 ProcessTask& _proc_task; 3502 G1CollectedHeap* _g1h; 3503 G1ParScanThreadStateSet* _pss; 3504 RefToScanQueueSet* _task_queues; 3505 ParallelTaskTerminator* _terminator; 3506 3507 public: 3508 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3509 G1CollectedHeap* g1h, 3510 G1ParScanThreadStateSet* per_thread_states, 3511 RefToScanQueueSet *task_queues, 3512 ParallelTaskTerminator* terminator) : 3513 AbstractGangTask("Process reference objects in parallel"), 3514 _proc_task(proc_task), 3515 _g1h(g1h), 3516 _pss(per_thread_states), 3517 _task_queues(task_queues), 3518 _terminator(terminator) 3519 {} 3520 3521 virtual void work(uint worker_id) { 3522 // The reference processing task executed by a single worker. 3523 ResourceMark rm; 3524 HandleMark hm; 3525 3526 G1STWIsAliveClosure is_alive(_g1h); 3527 3528 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3529 pss->set_ref_discoverer(NULL); 3530 3531 // Keep alive closure. 3532 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3533 3534 // Complete GC closure 3535 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator); 3536 3537 // Call the reference processing task's work routine. 3538 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3539 3540 // Note we cannot assert that the refs array is empty here as not all 3541 // of the processing tasks (specifically phase2 - pp2_work) execute 3542 // the complete_gc closure (which ordinarily would drain the queue) so 3543 // the queue may not be empty. 3544 } 3545 }; 3546 3547 // Driver routine for parallel reference processing. 3548 // Creates an instance of the ref processing gang 3549 // task and has the worker threads execute it. 3550 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3551 assert(_workers != NULL, "Need parallel worker threads."); 3552 3553 assert(_workers->active_workers() >= ergo_workers, 3554 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3555 ergo_workers, _workers->active_workers()); 3556 ParallelTaskTerminator terminator(ergo_workers, _queues); 3557 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 3558 3559 _workers->run_task(&proc_task_proxy, ergo_workers); 3560 } 3561 3562 // End of weak reference support closures 3563 3564 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3565 double ref_proc_start = os::elapsedTime(); 3566 3567 ReferenceProcessor* rp = _ref_processor_stw; 3568 assert(rp->discovery_enabled(), "should have been enabled"); 3569 3570 // Closure to test whether a referent is alive. 3571 G1STWIsAliveClosure is_alive(this); 3572 3573 // Even when parallel reference processing is enabled, the processing 3574 // of JNI refs is serial and performed serially by the current thread 3575 // rather than by a worker. The following PSS will be used for processing 3576 // JNI refs. 3577 3578 // Use only a single queue for this PSS. 3579 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3580 pss->set_ref_discoverer(NULL); 3581 assert(pss->queue_is_empty(), "pre-condition"); 3582 3583 // Keep alive closure. 3584 G1CopyingKeepAliveClosure keep_alive(this, pss); 3585 3586 // Serial Complete GC closure 3587 G1STWDrainQueueClosure drain_queue(this, pss); 3588 3589 // Setup the soft refs policy... 3590 rp->setup_policy(false); 3591 3592 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times(); 3593 3594 ReferenceProcessorStats stats; 3595 if (!rp->processing_is_mt()) { 3596 // Serial reference processing... 3597 stats = rp->process_discovered_references(&is_alive, 3598 &keep_alive, 3599 &drain_queue, 3600 NULL, 3601 pt); 3602 } else { 3603 uint no_of_gc_workers = workers()->active_workers(); 3604 3605 // Parallel reference processing 3606 assert(no_of_gc_workers <= rp->max_num_queues(), 3607 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3608 no_of_gc_workers, rp->max_num_queues()); 3609 3610 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3611 stats = rp->process_discovered_references(&is_alive, 3612 &keep_alive, 3613 &drain_queue, 3614 &par_task_executor, 3615 pt); 3616 } 3617 3618 _gc_tracer_stw->report_gc_reference_stats(stats); 3619 3620 // We have completed copying any necessary live referent objects. 3621 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3622 3623 make_pending_list_reachable(); 3624 3625 rp->verify_no_references_recorded(); 3626 3627 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3628 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3629 } 3630 3631 void G1CollectedHeap::make_pending_list_reachable() { 3632 if (collector_state()->in_initial_mark_gc()) { 3633 oop pll_head = Universe::reference_pending_list(); 3634 if (pll_head != NULL) { 3635 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3636 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3637 } 3638 } 3639 } 3640 3641 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3642 double merge_pss_time_start = os::elapsedTime(); 3643 per_thread_states->flush(); 3644 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 3645 } 3646 3647 void G1CollectedHeap::pre_evacuate_collection_set() { 3648 _expand_heap_after_alloc_failure = true; 3649 _evacuation_failed = false; 3650 3651 // Disable the hot card cache. 3652 _hot_card_cache->reset_hot_cache_claimed_index(); 3653 _hot_card_cache->set_use_cache(false); 3654 3655 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 3656 _preserved_marks_set.assert_empty(); 3657 3658 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3659 3660 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3661 if (collector_state()->in_initial_mark_gc()) { 3662 double start_clear_claimed_marks = os::elapsedTime(); 3663 3664 ClassLoaderDataGraph::clear_claimed_marks(); 3665 3666 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3667 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3668 } 3669 } 3670 3671 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3672 // Should G1EvacuationFailureALot be in effect for this GC? 3673 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3674 3675 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 3676 3677 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3678 3679 double start_par_time_sec = os::elapsedTime(); 3680 double end_par_time_sec; 3681 3682 { 3683 const uint n_workers = workers()->active_workers(); 3684 G1RootProcessor root_processor(this, n_workers); 3685 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 3686 3687 print_termination_stats_hdr(); 3688 3689 workers()->run_task(&g1_par_task); 3690 end_par_time_sec = os::elapsedTime(); 3691 3692 // Closing the inner scope will execute the destructor 3693 // for the G1RootProcessor object. We record the current 3694 // elapsed time before closing the scope so that time 3695 // taken for the destructor is NOT included in the 3696 // reported parallel time. 3697 } 3698 3699 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 3700 phase_times->record_par_time(par_time_ms); 3701 3702 double code_root_fixup_time_ms = 3703 (os::elapsedTime() - end_par_time_sec) * 1000.0; 3704 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 3705 } 3706 3707 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3708 // Also cleans the card table from temporary duplicate detection information used 3709 // during UpdateRS/ScanRS. 3710 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 3711 3712 // Process any discovered reference objects - we have 3713 // to do this _before_ we retire the GC alloc regions 3714 // as we may have to copy some 'reachable' referent 3715 // objects (and their reachable sub-graphs) that were 3716 // not copied during the pause. 3717 process_discovered_references(per_thread_states); 3718 3719 // FIXME 3720 // CM's reference processing also cleans up the string table. 3721 // Should we do that here also? We could, but it is a serial operation 3722 // and could significantly increase the pause time. 3723 3724 G1STWIsAliveClosure is_alive(this); 3725 G1KeepAliveClosure keep_alive(this); 3726 3727 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, 3728 g1_policy()->phase_times()->weak_phase_times()); 3729 3730 if (G1StringDedup::is_enabled()) { 3731 double fixup_start = os::elapsedTime(); 3732 3733 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times()); 3734 3735 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 3736 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms); 3737 } 3738 3739 if (evacuation_failed()) { 3740 restore_after_evac_failure(); 3741 3742 // Reset the G1EvacuationFailureALot counters and flags 3743 // Note: the values are reset only when an actual 3744 // evacuation failure occurs. 3745 NOT_PRODUCT(reset_evacuation_should_fail();) 3746 } 3747 3748 _preserved_marks_set.assert_empty(); 3749 3750 _allocator->release_gc_alloc_regions(evacuation_info); 3751 3752 merge_per_thread_state_info(per_thread_states); 3753 3754 // Reset and re-enable the hot card cache. 3755 // Note the counts for the cards in the regions in the 3756 // collection set are reset when the collection set is freed. 3757 _hot_card_cache->reset_hot_cache(); 3758 _hot_card_cache->set_use_cache(true); 3759 3760 purge_code_root_memory(); 3761 3762 redirty_logged_cards(); 3763 #if COMPILER2_OR_JVMCI 3764 double start = os::elapsedTime(); 3765 DerivedPointerTable::update_pointers(); 3766 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 3767 #endif 3768 g1_policy()->print_age_table(); 3769 } 3770 3771 void G1CollectedHeap::record_obj_copy_mem_stats() { 3772 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 3773 3774 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 3775 create_g1_evac_summary(&_old_evac_stats)); 3776 } 3777 3778 void G1CollectedHeap::free_region(HeapRegion* hr, 3779 FreeRegionList* free_list, 3780 bool skip_remset, 3781 bool skip_hot_card_cache, 3782 bool locked) { 3783 assert(!hr->is_free(), "the region should not be free"); 3784 assert(!hr->is_empty(), "the region should not be empty"); 3785 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 3786 assert(free_list != NULL, "pre-condition"); 3787 3788 if (G1VerifyBitmaps) { 3789 MemRegion mr(hr->bottom(), hr->end()); 3790 concurrent_mark()->clear_range_in_prev_bitmap(mr); 3791 } 3792 3793 // Clear the card counts for this region. 3794 // Note: we only need to do this if the region is not young 3795 // (since we don't refine cards in young regions). 3796 if (!skip_hot_card_cache && !hr->is_young()) { 3797 _hot_card_cache->reset_card_counts(hr); 3798 } 3799 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 3800 _g1_policy->remset_tracker()->update_at_free(hr); 3801 free_list->add_ordered(hr); 3802 } 3803 3804 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 3805 FreeRegionList* free_list) { 3806 assert(hr->is_humongous(), "this is only for humongous regions"); 3807 assert(free_list != NULL, "pre-condition"); 3808 hr->clear_humongous(); 3809 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */); 3810 } 3811 3812 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 3813 const uint humongous_regions_removed) { 3814 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 3815 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 3816 _old_set.bulk_remove(old_regions_removed); 3817 _humongous_set.bulk_remove(humongous_regions_removed); 3818 } 3819 3820 } 3821 3822 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 3823 assert(list != NULL, "list can't be null"); 3824 if (!list->is_empty()) { 3825 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 3826 _hrm.insert_list_into_free_list(list); 3827 } 3828 } 3829 3830 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 3831 decrease_used(bytes); 3832 } 3833 3834 class G1FreeCollectionSetTask : public AbstractGangTask { 3835 private: 3836 3837 // Closure applied to all regions in the collection set to do work that needs to 3838 // be done serially in a single thread. 3839 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 3840 private: 3841 EvacuationInfo* _evacuation_info; 3842 const size_t* _surviving_young_words; 3843 3844 // Bytes used in successfully evacuated regions before the evacuation. 3845 size_t _before_used_bytes; 3846 // Bytes used in unsucessfully evacuated regions before the evacuation 3847 size_t _after_used_bytes; 3848 3849 size_t _bytes_allocated_in_old_since_last_gc; 3850 3851 size_t _failure_used_words; 3852 size_t _failure_waste_words; 3853 3854 FreeRegionList _local_free_list; 3855 public: 3856 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 3857 HeapRegionClosure(), 3858 _evacuation_info(evacuation_info), 3859 _surviving_young_words(surviving_young_words), 3860 _before_used_bytes(0), 3861 _after_used_bytes(0), 3862 _bytes_allocated_in_old_since_last_gc(0), 3863 _failure_used_words(0), 3864 _failure_waste_words(0), 3865 _local_free_list("Local Region List for CSet Freeing") { 3866 } 3867 3868 virtual bool do_heap_region(HeapRegion* r) { 3869 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3870 3871 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 3872 g1h->clear_in_cset(r); 3873 3874 if (r->is_young()) { 3875 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(), 3876 "Young index %d is wrong for region %u of type %s with %u young regions", 3877 r->young_index_in_cset(), 3878 r->hrm_index(), 3879 r->get_type_str(), 3880 g1h->collection_set()->young_region_length()); 3881 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 3882 r->record_surv_words_in_group(words_survived); 3883 } 3884 3885 if (!r->evacuation_failed()) { 3886 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 3887 _before_used_bytes += r->used(); 3888 g1h->free_region(r, 3889 &_local_free_list, 3890 true, /* skip_remset */ 3891 true, /* skip_hot_card_cache */ 3892 true /* locked */); 3893 } else { 3894 r->uninstall_surv_rate_group(); 3895 r->set_young_index_in_cset(-1); 3896 r->set_evacuation_failed(false); 3897 // When moving a young gen region to old gen, we "allocate" that whole region 3898 // there. This is in addition to any already evacuated objects. Notify the 3899 // policy about that. 3900 // Old gen regions do not cause an additional allocation: both the objects 3901 // still in the region and the ones already moved are accounted for elsewhere. 3902 if (r->is_young()) { 3903 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 3904 } 3905 // The region is now considered to be old. 3906 r->set_old(); 3907 // Do some allocation statistics accounting. Regions that failed evacuation 3908 // are always made old, so there is no need to update anything in the young 3909 // gen statistics, but we need to update old gen statistics. 3910 size_t used_words = r->marked_bytes() / HeapWordSize; 3911 3912 _failure_used_words += used_words; 3913 _failure_waste_words += HeapRegion::GrainWords - used_words; 3914 3915 g1h->old_set_add(r); 3916 _after_used_bytes += r->used(); 3917 } 3918 return false; 3919 } 3920 3921 void complete_work() { 3922 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3923 3924 _evacuation_info->set_regions_freed(_local_free_list.length()); 3925 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 3926 3927 g1h->prepend_to_freelist(&_local_free_list); 3928 g1h->decrement_summary_bytes(_before_used_bytes); 3929 3930 G1Policy* policy = g1h->g1_policy(); 3931 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 3932 3933 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 3934 } 3935 }; 3936 3937 G1CollectionSet* _collection_set; 3938 G1SerialFreeCollectionSetClosure _cl; 3939 const size_t* _surviving_young_words; 3940 3941 size_t _rs_lengths; 3942 3943 volatile jint _serial_work_claim; 3944 3945 struct WorkItem { 3946 uint region_idx; 3947 bool is_young; 3948 bool evacuation_failed; 3949 3950 WorkItem(HeapRegion* r) { 3951 region_idx = r->hrm_index(); 3952 is_young = r->is_young(); 3953 evacuation_failed = r->evacuation_failed(); 3954 } 3955 }; 3956 3957 volatile size_t _parallel_work_claim; 3958 size_t _num_work_items; 3959 WorkItem* _work_items; 3960 3961 void do_serial_work() { 3962 // Need to grab the lock to be allowed to modify the old region list. 3963 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 3964 _collection_set->iterate(&_cl); 3965 } 3966 3967 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 3968 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3969 3970 HeapRegion* r = g1h->region_at(region_idx); 3971 assert(!g1h->is_on_master_free_list(r), "sanity"); 3972 3973 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths); 3974 3975 if (!is_young) { 3976 g1h->_hot_card_cache->reset_card_counts(r); 3977 } 3978 3979 if (!evacuation_failed) { 3980 r->rem_set()->clear_locked(); 3981 } 3982 } 3983 3984 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 3985 private: 3986 size_t _cur_idx; 3987 WorkItem* _work_items; 3988 public: 3989 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 3990 3991 virtual bool do_heap_region(HeapRegion* r) { 3992 _work_items[_cur_idx++] = WorkItem(r); 3993 return false; 3994 } 3995 }; 3996 3997 void prepare_work() { 3998 G1PrepareFreeCollectionSetClosure cl(_work_items); 3999 _collection_set->iterate(&cl); 4000 } 4001 4002 void complete_work() { 4003 _cl.complete_work(); 4004 4005 G1Policy* policy = G1CollectedHeap::heap()->g1_policy(); 4006 policy->record_max_rs_lengths(_rs_lengths); 4007 policy->cset_regions_freed(); 4008 } 4009 public: 4010 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4011 AbstractGangTask("G1 Free Collection Set"), 4012 _collection_set(collection_set), 4013 _cl(evacuation_info, surviving_young_words), 4014 _surviving_young_words(surviving_young_words), 4015 _rs_lengths(0), 4016 _serial_work_claim(0), 4017 _parallel_work_claim(0), 4018 _num_work_items(collection_set->region_length()), 4019 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4020 prepare_work(); 4021 } 4022 4023 ~G1FreeCollectionSetTask() { 4024 complete_work(); 4025 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4026 } 4027 4028 // Chunk size for work distribution. The chosen value has been determined experimentally 4029 // to be a good tradeoff between overhead and achievable parallelism. 4030 static uint chunk_size() { return 32; } 4031 4032 virtual void work(uint worker_id) { 4033 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4034 4035 // Claim serial work. 4036 if (_serial_work_claim == 0) { 4037 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4038 if (value == 0) { 4039 double serial_time = os::elapsedTime(); 4040 do_serial_work(); 4041 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4042 } 4043 } 4044 4045 // Start parallel work. 4046 double young_time = 0.0; 4047 bool has_young_time = false; 4048 double non_young_time = 0.0; 4049 bool has_non_young_time = false; 4050 4051 while (true) { 4052 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4053 size_t cur = end - chunk_size(); 4054 4055 if (cur >= _num_work_items) { 4056 break; 4057 } 4058 4059 JFR_ONLY(EventGCPhaseParallel event;) 4060 double start_time = os::elapsedTime(); 4061 4062 end = MIN2(end, _num_work_items); 4063 4064 for (; cur < end; cur++) { 4065 bool is_young = _work_items[cur].is_young; 4066 4067 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4068 4069 double end_time = os::elapsedTime(); 4070 double time_taken = end_time - start_time; 4071 if (is_young) { 4072 young_time += time_taken; 4073 has_young_time = true; 4074 JFR_ONLY(event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));) 4075 } else { 4076 non_young_time += time_taken; 4077 has_non_young_time = true; 4078 JFR_ONLY(event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));) 4079 } 4080 start_time = end_time; 4081 } 4082 } 4083 4084 if (has_young_time) { 4085 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4086 } 4087 if (has_non_young_time) { 4088 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4089 } 4090 } 4091 }; 4092 4093 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4094 _eden.clear(); 4095 4096 double free_cset_start_time = os::elapsedTime(); 4097 4098 { 4099 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U); 4100 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4101 4102 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4103 4104 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4105 cl.name(), 4106 num_workers, 4107 _collection_set.region_length()); 4108 workers()->run_task(&cl, num_workers); 4109 } 4110 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4111 4112 collection_set->clear(); 4113 } 4114 4115 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4116 private: 4117 FreeRegionList* _free_region_list; 4118 HeapRegionSet* _proxy_set; 4119 uint _humongous_objects_reclaimed; 4120 uint _humongous_regions_reclaimed; 4121 size_t _freed_bytes; 4122 public: 4123 4124 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4125 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4126 } 4127 4128 virtual bool do_heap_region(HeapRegion* r) { 4129 if (!r->is_starts_humongous()) { 4130 return false; 4131 } 4132 4133 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4134 4135 oop obj = (oop)r->bottom(); 4136 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4137 4138 // The following checks whether the humongous object is live are sufficient. 4139 // The main additional check (in addition to having a reference from the roots 4140 // or the young gen) is whether the humongous object has a remembered set entry. 4141 // 4142 // A humongous object cannot be live if there is no remembered set for it 4143 // because: 4144 // - there can be no references from within humongous starts regions referencing 4145 // the object because we never allocate other objects into them. 4146 // (I.e. there are no intra-region references that may be missed by the 4147 // remembered set) 4148 // - as soon there is a remembered set entry to the humongous starts region 4149 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4150 // until the end of a concurrent mark. 4151 // 4152 // It is not required to check whether the object has been found dead by marking 4153 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4154 // all objects allocated during that time are considered live. 4155 // SATB marking is even more conservative than the remembered set. 4156 // So if at this point in the collection there is no remembered set entry, 4157 // nobody has a reference to it. 4158 // At the start of collection we flush all refinement logs, and remembered sets 4159 // are completely up-to-date wrt to references to the humongous object. 4160 // 4161 // Other implementation considerations: 4162 // - never consider object arrays at this time because they would pose 4163 // considerable effort for cleaning up the the remembered sets. This is 4164 // required because stale remembered sets might reference locations that 4165 // are currently allocated into. 4166 uint region_idx = r->hrm_index(); 4167 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4168 !r->rem_set()->is_empty()) { 4169 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", 4170 region_idx, 4171 (size_t)obj->size() * HeapWordSize, 4172 p2i(r->bottom()), 4173 r->rem_set()->occupied(), 4174 r->rem_set()->strong_code_roots_list_length(), 4175 next_bitmap->is_marked(r->bottom()), 4176 g1h->is_humongous_reclaim_candidate(region_idx), 4177 obj->is_typeArray() 4178 ); 4179 return false; 4180 } 4181 4182 guarantee(obj->is_typeArray(), 4183 "Only eagerly reclaiming type arrays is supported, but the object " 4184 PTR_FORMAT " is not.", p2i(r->bottom())); 4185 4186 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", 4187 region_idx, 4188 (size_t)obj->size() * HeapWordSize, 4189 p2i(r->bottom()), 4190 r->rem_set()->occupied(), 4191 r->rem_set()->strong_code_roots_list_length(), 4192 next_bitmap->is_marked(r->bottom()), 4193 g1h->is_humongous_reclaim_candidate(region_idx), 4194 obj->is_typeArray() 4195 ); 4196 4197 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4198 cm->humongous_object_eagerly_reclaimed(r); 4199 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4200 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4201 region_idx, 4202 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4203 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4204 _humongous_objects_reclaimed++; 4205 do { 4206 HeapRegion* next = g1h->next_region_in_humongous(r); 4207 _freed_bytes += r->used(); 4208 r->set_containing_set(NULL); 4209 _humongous_regions_reclaimed++; 4210 g1h->free_humongous_region(r, _free_region_list); 4211 r = next; 4212 } while (r != NULL); 4213 4214 return false; 4215 } 4216 4217 uint humongous_objects_reclaimed() { 4218 return _humongous_objects_reclaimed; 4219 } 4220 4221 uint humongous_regions_reclaimed() { 4222 return _humongous_regions_reclaimed; 4223 } 4224 4225 size_t bytes_freed() const { 4226 return _freed_bytes; 4227 } 4228 }; 4229 4230 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4231 assert_at_safepoint_on_vm_thread(); 4232 4233 if (!G1EagerReclaimHumongousObjects || 4234 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4235 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4236 return; 4237 } 4238 4239 double start_time = os::elapsedTime(); 4240 4241 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4242 4243 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4244 heap_region_iterate(&cl); 4245 4246 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4247 4248 G1HRPrinter* hrp = hr_printer(); 4249 if (hrp->is_active()) { 4250 FreeRegionListIterator iter(&local_cleanup_list); 4251 while (iter.more_available()) { 4252 HeapRegion* hr = iter.get_next(); 4253 hrp->cleanup(hr); 4254 } 4255 } 4256 4257 prepend_to_freelist(&local_cleanup_list); 4258 decrement_summary_bytes(cl.bytes_freed()); 4259 4260 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4261 cl.humongous_objects_reclaimed()); 4262 } 4263 4264 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4265 public: 4266 virtual bool do_heap_region(HeapRegion* r) { 4267 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4268 G1CollectedHeap::heap()->clear_in_cset(r); 4269 r->set_young_index_in_cset(-1); 4270 return false; 4271 } 4272 }; 4273 4274 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4275 G1AbandonCollectionSetClosure cl; 4276 collection_set->iterate(&cl); 4277 4278 collection_set->clear(); 4279 collection_set->stop_incremental_building(); 4280 } 4281 4282 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4283 return _allocator->is_retained_old_region(hr); 4284 } 4285 4286 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4287 _eden.add(hr); 4288 _g1_policy->set_region_eden(hr); 4289 } 4290 4291 #ifdef ASSERT 4292 4293 class NoYoungRegionsClosure: public HeapRegionClosure { 4294 private: 4295 bool _success; 4296 public: 4297 NoYoungRegionsClosure() : _success(true) { } 4298 bool do_heap_region(HeapRegion* r) { 4299 if (r->is_young()) { 4300 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4301 p2i(r->bottom()), p2i(r->end())); 4302 _success = false; 4303 } 4304 return false; 4305 } 4306 bool success() { return _success; } 4307 }; 4308 4309 bool G1CollectedHeap::check_young_list_empty() { 4310 bool ret = (young_regions_count() == 0); 4311 4312 NoYoungRegionsClosure closure; 4313 heap_region_iterate(&closure); 4314 ret = ret && closure.success(); 4315 4316 return ret; 4317 } 4318 4319 #endif // ASSERT 4320 4321 class TearDownRegionSetsClosure : public HeapRegionClosure { 4322 HeapRegionSet *_old_set; 4323 4324 public: 4325 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4326 4327 bool do_heap_region(HeapRegion* r) { 4328 if (r->is_old()) { 4329 _old_set->remove(r); 4330 } else if(r->is_young()) { 4331 r->uninstall_surv_rate_group(); 4332 } else { 4333 // We ignore free regions, we'll empty the free list afterwards. 4334 // We ignore humongous and archive regions, we're not tearing down these 4335 // sets. 4336 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4337 "it cannot be another type"); 4338 } 4339 return false; 4340 } 4341 4342 ~TearDownRegionSetsClosure() { 4343 assert(_old_set->is_empty(), "post-condition"); 4344 } 4345 }; 4346 4347 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4348 assert_at_safepoint_on_vm_thread(); 4349 4350 if (!free_list_only) { 4351 TearDownRegionSetsClosure cl(&_old_set); 4352 heap_region_iterate(&cl); 4353 4354 // Note that emptying the _young_list is postponed and instead done as 4355 // the first step when rebuilding the regions sets again. The reason for 4356 // this is that during a full GC string deduplication needs to know if 4357 // a collected region was young or old when the full GC was initiated. 4358 } 4359 _hrm.remove_all_free_regions(); 4360 } 4361 4362 void G1CollectedHeap::increase_used(size_t bytes) { 4363 _summary_bytes_used += bytes; 4364 } 4365 4366 void G1CollectedHeap::decrease_used(size_t bytes) { 4367 assert(_summary_bytes_used >= bytes, 4368 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4369 _summary_bytes_used, bytes); 4370 _summary_bytes_used -= bytes; 4371 } 4372 4373 void G1CollectedHeap::set_used(size_t bytes) { 4374 _summary_bytes_used = bytes; 4375 } 4376 4377 class RebuildRegionSetsClosure : public HeapRegionClosure { 4378 private: 4379 bool _free_list_only; 4380 4381 HeapRegionSet* _old_set; 4382 HeapRegionManager* _hrm; 4383 4384 size_t _total_used; 4385 4386 public: 4387 RebuildRegionSetsClosure(bool free_list_only, 4388 HeapRegionSet* old_set, 4389 HeapRegionManager* hrm) : 4390 _free_list_only(free_list_only), 4391 _old_set(old_set), _hrm(hrm), _total_used(0) { 4392 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4393 if (!free_list_only) { 4394 assert(_old_set->is_empty(), "pre-condition"); 4395 } 4396 } 4397 4398 bool do_heap_region(HeapRegion* r) { 4399 // After full GC, no region should have a remembered set. 4400 r->rem_set()->clear(true); 4401 if (r->is_empty()) { 4402 // Add free regions to the free list 4403 r->set_free(); 4404 _hrm->insert_into_free_list(r); 4405 } else if (!_free_list_only) { 4406 4407 if (r->is_archive() || r->is_humongous()) { 4408 // We ignore archive and humongous regions. We left these sets unchanged. 4409 } else { 4410 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4411 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4412 r->move_to_old(); 4413 _old_set->add(r); 4414 } 4415 _total_used += r->used(); 4416 } 4417 4418 return false; 4419 } 4420 4421 size_t total_used() { 4422 return _total_used; 4423 } 4424 }; 4425 4426 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4427 assert_at_safepoint_on_vm_thread(); 4428 4429 if (!free_list_only) { 4430 _eden.clear(); 4431 _survivor.clear(); 4432 } 4433 4434 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 4435 heap_region_iterate(&cl); 4436 4437 if (!free_list_only) { 4438 set_used(cl.total_used()); 4439 if (_archive_allocator != NULL) { 4440 _archive_allocator->clear_used(); 4441 } 4442 } 4443 assert(used_unlocked() == recalculate_used(), 4444 "inconsistent used_unlocked(), " 4445 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 4446 used_unlocked(), recalculate_used()); 4447 } 4448 4449 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 4450 HeapRegion* hr = heap_region_containing(p); 4451 return hr->is_in(p); 4452 } 4453 4454 // Methods for the mutator alloc region 4455 4456 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4457 bool force) { 4458 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4459 bool should_allocate = g1_policy()->should_allocate_mutator_region(); 4460 if (force || should_allocate) { 4461 HeapRegion* new_alloc_region = new_region(word_size, 4462 false /* is_old */, 4463 false /* do_expand */); 4464 if (new_alloc_region != NULL) { 4465 set_region_short_lived_locked(new_alloc_region); 4466 _hr_printer.alloc(new_alloc_region, !should_allocate); 4467 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4468 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region); 4469 return new_alloc_region; 4470 } 4471 } 4472 return NULL; 4473 } 4474 4475 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4476 size_t allocated_bytes) { 4477 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4478 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4479 4480 collection_set()->add_eden_region(alloc_region); 4481 increase_used(allocated_bytes); 4482 _hr_printer.retire(alloc_region); 4483 // We update the eden sizes here, when the region is retired, 4484 // instead of when it's allocated, since this is the point that its 4485 // used space has been recorded in _summary_bytes_used. 4486 g1mm()->update_eden_size(); 4487 } 4488 4489 // Methods for the GC alloc regions 4490 4491 bool G1CollectedHeap::has_more_regions(InCSetState dest) { 4492 if (dest.is_old()) { 4493 return true; 4494 } else { 4495 return survivor_regions_count() < g1_policy()->max_survivor_regions(); 4496 } 4497 } 4498 4499 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) { 4500 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4501 4502 if (!has_more_regions(dest)) { 4503 return NULL; 4504 } 4505 4506 const bool is_survivor = dest.is_young(); 4507 4508 HeapRegion* new_alloc_region = new_region(word_size, 4509 !is_survivor, 4510 true /* do_expand */); 4511 if (new_alloc_region != NULL) { 4512 if (is_survivor) { 4513 new_alloc_region->set_survivor(); 4514 _survivor.add(new_alloc_region); 4515 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4516 } else { 4517 new_alloc_region->set_old(); 4518 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4519 } 4520 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region); 4521 _hr_printer.alloc(new_alloc_region); 4522 bool during_im = collector_state()->in_initial_mark_gc(); 4523 new_alloc_region->note_start_of_copying(during_im); 4524 return new_alloc_region; 4525 } 4526 return NULL; 4527 } 4528 4529 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4530 size_t allocated_bytes, 4531 InCSetState dest) { 4532 bool during_im = collector_state()->in_initial_mark_gc(); 4533 alloc_region->note_end_of_copying(during_im); 4534 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 4535 if (dest.is_old()) { 4536 old_set_add(alloc_region); 4537 } 4538 _hr_printer.retire(alloc_region); 4539 } 4540 4541 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4542 bool expanded = false; 4543 uint index = _hrm.find_highest_free(&expanded); 4544 4545 if (index != G1_NO_HRM_INDEX) { 4546 if (expanded) { 4547 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4548 HeapRegion::GrainWords * HeapWordSize); 4549 } 4550 _hrm.allocate_free_regions_starting_at(index, 1); 4551 return region_at(index); 4552 } 4553 return NULL; 4554 } 4555 4556 // Optimized nmethod scanning 4557 4558 class RegisterNMethodOopClosure: public OopClosure { 4559 G1CollectedHeap* _g1h; 4560 nmethod* _nm; 4561 4562 template <class T> void do_oop_work(T* p) { 4563 T heap_oop = RawAccess<>::oop_load(p); 4564 if (!CompressedOops::is_null(heap_oop)) { 4565 oop obj = CompressedOops::decode_not_null(heap_oop); 4566 HeapRegion* hr = _g1h->heap_region_containing(obj); 4567 assert(!hr->is_continues_humongous(), 4568 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4569 " starting at " HR_FORMAT, 4570 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4571 4572 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4573 hr->add_strong_code_root_locked(_nm); 4574 } 4575 } 4576 4577 public: 4578 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4579 _g1h(g1h), _nm(nm) {} 4580 4581 void do_oop(oop* p) { do_oop_work(p); } 4582 void do_oop(narrowOop* p) { do_oop_work(p); } 4583 }; 4584 4585 class UnregisterNMethodOopClosure: public OopClosure { 4586 G1CollectedHeap* _g1h; 4587 nmethod* _nm; 4588 4589 template <class T> void do_oop_work(T* p) { 4590 T heap_oop = RawAccess<>::oop_load(p); 4591 if (!CompressedOops::is_null(heap_oop)) { 4592 oop obj = CompressedOops::decode_not_null(heap_oop); 4593 HeapRegion* hr = _g1h->heap_region_containing(obj); 4594 assert(!hr->is_continues_humongous(), 4595 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4596 " starting at " HR_FORMAT, 4597 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4598 4599 hr->remove_strong_code_root(_nm); 4600 } 4601 } 4602 4603 public: 4604 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4605 _g1h(g1h), _nm(nm) {} 4606 4607 void do_oop(oop* p) { do_oop_work(p); } 4608 void do_oop(narrowOop* p) { do_oop_work(p); } 4609 }; 4610 4611 // Returns true if the reference points to an object that 4612 // can move in an incremental collection. 4613 bool G1CollectedHeap::is_scavengable(oop obj) { 4614 HeapRegion* hr = heap_region_containing(obj); 4615 return !hr->is_pinned(); 4616 } 4617 4618 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4619 guarantee(nm != NULL, "sanity"); 4620 RegisterNMethodOopClosure reg_cl(this, nm); 4621 nm->oops_do(®_cl); 4622 } 4623 4624 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4625 guarantee(nm != NULL, "sanity"); 4626 UnregisterNMethodOopClosure reg_cl(this, nm); 4627 nm->oops_do(®_cl, true); 4628 } 4629 4630 void G1CollectedHeap::purge_code_root_memory() { 4631 double purge_start = os::elapsedTime(); 4632 G1CodeRootSet::purge(); 4633 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4634 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4635 } 4636 4637 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4638 G1CollectedHeap* _g1h; 4639 4640 public: 4641 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4642 _g1h(g1h) {} 4643 4644 void do_code_blob(CodeBlob* cb) { 4645 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4646 if (nm == NULL) { 4647 return; 4648 } 4649 4650 if (ScavengeRootsInCode) { 4651 _g1h->register_nmethod(nm); 4652 } 4653 } 4654 }; 4655 4656 void G1CollectedHeap::rebuild_strong_code_roots() { 4657 RebuildStrongCodeRootClosure blob_cl(this); 4658 CodeCache::blobs_do(&blob_cl); 4659 } 4660 4661 void G1CollectedHeap::initialize_serviceability() { 4662 _g1mm->initialize_serviceability(); 4663 } 4664 4665 MemoryUsage G1CollectedHeap::memory_usage() { 4666 return _g1mm->memory_usage(); 4667 } 4668 4669 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4670 return _g1mm->memory_managers(); 4671 } 4672 4673 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4674 return _g1mm->memory_pools(); 4675 }