1 /* 2 * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/metadataOnStackMark.hpp" 27 #include "classfile/stringTable.hpp" 28 #include "classfile/symbolTable.hpp" 29 #include "code/codeCache.hpp" 30 #include "code/icBuffer.hpp" 31 #include "gc/g1/g1Allocator.inline.hpp" 32 #include "gc/g1/g1BarrierSet.hpp" 33 #include "gc/g1/g1CollectedHeap.inline.hpp" 34 #include "gc/g1/g1CollectionSet.hpp" 35 #include "gc/g1/g1CollectorPolicy.hpp" 36 #include "gc/g1/g1CollectorState.hpp" 37 #include "gc/g1/g1ConcurrentRefine.hpp" 38 #include "gc/g1/g1ConcurrentRefineThread.hpp" 39 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp" 40 #include "gc/g1/g1EvacStats.inline.hpp" 41 #include "gc/g1/g1FullCollector.hpp" 42 #include "gc/g1/g1GCPhaseTimes.hpp" 43 #include "gc/g1/g1HeapSizingPolicy.hpp" 44 #include "gc/g1/g1HeapTransition.hpp" 45 #include "gc/g1/g1HeapVerifier.hpp" 46 #include "gc/g1/g1HotCardCache.hpp" 47 #include "gc/g1/g1MemoryPool.hpp" 48 #include "gc/g1/g1OopClosures.inline.hpp" 49 #include "gc/g1/g1ParScanThreadState.inline.hpp" 50 #include "gc/g1/g1Policy.hpp" 51 #include "gc/g1/g1RegionToSpaceMapper.hpp" 52 #include "gc/g1/g1RemSet.hpp" 53 #include "gc/g1/g1RootClosures.hpp" 54 #include "gc/g1/g1RootProcessor.hpp" 55 #include "gc/g1/g1StringDedup.hpp" 56 #include "gc/g1/g1ThreadLocalData.hpp" 57 #include "gc/g1/g1YCTypes.hpp" 58 #include "gc/g1/g1YoungRemSetSamplingThread.hpp" 59 #include "gc/g1/heapRegion.inline.hpp" 60 #include "gc/g1/heapRegionRemSet.hpp" 61 #include "gc/g1/heapRegionSet.inline.hpp" 62 #include "gc/g1/vm_operations_g1.hpp" 63 #include "gc/shared/adaptiveSizePolicy.hpp" 64 #include "gc/shared/gcHeapSummary.hpp" 65 #include "gc/shared/gcId.hpp" 66 #include "gc/shared/gcLocker.hpp" 67 #include "gc/shared/gcTimer.hpp" 68 #include "gc/shared/gcTrace.hpp" 69 #include "gc/shared/gcTraceTime.inline.hpp" 70 #include "gc/shared/generationSpec.hpp" 71 #include "gc/shared/isGCActiveMark.hpp" 72 #include "gc/shared/oopStorageParState.hpp" 73 #include "gc/shared/preservedMarks.inline.hpp" 74 #include "gc/shared/suspendibleThreadSet.hpp" 75 #include "gc/shared/referenceProcessor.inline.hpp" 76 #include "gc/shared/taskqueue.inline.hpp" 77 #include "gc/shared/weakProcessor.hpp" 78 #include "logging/log.hpp" 79 #include "memory/allocation.hpp" 80 #include "memory/iterator.hpp" 81 #include "memory/resourceArea.hpp" 82 #include "oops/access.inline.hpp" 83 #include "oops/compressedOops.inline.hpp" 84 #include "oops/oop.inline.hpp" 85 #include "prims/resolvedMethodTable.hpp" 86 #include "runtime/atomic.hpp" 87 #include "runtime/flags/flagSetting.hpp" 88 #include "runtime/handles.inline.hpp" 89 #include "runtime/init.hpp" 90 #include "runtime/orderAccess.hpp" 91 #include "runtime/threadSMR.hpp" 92 #include "runtime/vmThread.hpp" 93 #include "utilities/align.hpp" 94 #include "utilities/globalDefinitions.hpp" 95 #include "utilities/stack.inline.hpp" 96 97 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 98 99 // INVARIANTS/NOTES 100 // 101 // All allocation activity covered by the G1CollectedHeap interface is 102 // serialized by acquiring the HeapLock. This happens in mem_allocate 103 // and allocate_new_tlab, which are the "entry" points to the 104 // allocation code from the rest of the JVM. (Note that this does not 105 // apply to TLAB allocation, which is not part of this interface: it 106 // is done by clients of this interface.) 107 108 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 109 private: 110 size_t _num_dirtied; 111 G1CollectedHeap* _g1h; 112 G1CardTable* _g1_ct; 113 114 HeapRegion* region_for_card(jbyte* card_ptr) const { 115 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr)); 116 } 117 118 bool will_become_free(HeapRegion* hr) const { 119 // A region will be freed by free_collection_set if the region is in the 120 // collection set and has not had an evacuation failure. 121 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 122 } 123 124 public: 125 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(), 126 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { } 127 128 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 129 HeapRegion* hr = region_for_card(card_ptr); 130 131 // Should only dirty cards in regions that won't be freed. 132 if (!will_become_free(hr)) { 133 *card_ptr = G1CardTable::dirty_card_val(); 134 _num_dirtied++; 135 } 136 137 return true; 138 } 139 140 size_t num_dirtied() const { return _num_dirtied; } 141 }; 142 143 144 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 145 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 146 } 147 148 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 149 // The from card cache is not the memory that is actually committed. So we cannot 150 // take advantage of the zero_filled parameter. 151 reset_from_card_cache(start_idx, num_regions); 152 } 153 154 155 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 156 MemRegion mr) { 157 return new HeapRegion(hrs_index, bot(), mr); 158 } 159 160 // Private methods. 161 162 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 163 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 164 "the only time we use this to allocate a humongous region is " 165 "when we are allocating a single humongous region"); 166 167 HeapRegion* res = _hrm.allocate_free_region(is_old); 168 169 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 170 // Currently, only attempts to allocate GC alloc regions set 171 // do_expand to true. So, we should only reach here during a 172 // safepoint. If this assumption changes we might have to 173 // reconsider the use of _expand_heap_after_alloc_failure. 174 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 175 176 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 177 word_size * HeapWordSize); 178 179 if (expand(word_size * HeapWordSize)) { 180 // Given that expand() succeeded in expanding the heap, and we 181 // always expand the heap by an amount aligned to the heap 182 // region size, the free list should in theory not be empty. 183 // In either case allocate_free_region() will check for NULL. 184 res = _hrm.allocate_free_region(is_old); 185 } else { 186 _expand_heap_after_alloc_failure = false; 187 } 188 } 189 return res; 190 } 191 192 HeapWord* 193 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 194 uint num_regions, 195 size_t word_size) { 196 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 197 assert(is_humongous(word_size), "word_size should be humongous"); 198 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 199 200 // Index of last region in the series. 201 uint last = first + num_regions - 1; 202 203 // We need to initialize the region(s) we just discovered. This is 204 // a bit tricky given that it can happen concurrently with 205 // refinement threads refining cards on these regions and 206 // potentially wanting to refine the BOT as they are scanning 207 // those cards (this can happen shortly after a cleanup; see CR 208 // 6991377). So we have to set up the region(s) carefully and in 209 // a specific order. 210 211 // The word size sum of all the regions we will allocate. 212 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 213 assert(word_size <= word_size_sum, "sanity"); 214 215 // This will be the "starts humongous" region. 216 HeapRegion* first_hr = region_at(first); 217 // The header of the new object will be placed at the bottom of 218 // the first region. 219 HeapWord* new_obj = first_hr->bottom(); 220 // This will be the new top of the new object. 221 HeapWord* obj_top = new_obj + word_size; 222 223 // First, we need to zero the header of the space that we will be 224 // allocating. When we update top further down, some refinement 225 // threads might try to scan the region. By zeroing the header we 226 // ensure that any thread that will try to scan the region will 227 // come across the zero klass word and bail out. 228 // 229 // NOTE: It would not have been correct to have used 230 // CollectedHeap::fill_with_object() and make the space look like 231 // an int array. The thread that is doing the allocation will 232 // later update the object header to a potentially different array 233 // type and, for a very short period of time, the klass and length 234 // fields will be inconsistent. This could cause a refinement 235 // thread to calculate the object size incorrectly. 236 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 237 238 // Next, pad out the unused tail of the last region with filler 239 // objects, for improved usage accounting. 240 // How many words we use for filler objects. 241 size_t word_fill_size = word_size_sum - word_size; 242 243 // How many words memory we "waste" which cannot hold a filler object. 244 size_t words_not_fillable = 0; 245 246 if (word_fill_size >= min_fill_size()) { 247 fill_with_objects(obj_top, word_fill_size); 248 } else if (word_fill_size > 0) { 249 // We have space to fill, but we cannot fit an object there. 250 words_not_fillable = word_fill_size; 251 word_fill_size = 0; 252 } 253 254 // We will set up the first region as "starts humongous". This 255 // will also update the BOT covering all the regions to reflect 256 // that there is a single object that starts at the bottom of the 257 // first region. 258 first_hr->set_starts_humongous(obj_top, word_fill_size); 259 _g1_policy->remset_tracker()->update_at_allocate(first_hr); 260 // Then, if there are any, we will set up the "continues 261 // humongous" regions. 262 HeapRegion* hr = NULL; 263 for (uint i = first + 1; i <= last; ++i) { 264 hr = region_at(i); 265 hr->set_continues_humongous(first_hr); 266 _g1_policy->remset_tracker()->update_at_allocate(hr); 267 } 268 269 // Up to this point no concurrent thread would have been able to 270 // do any scanning on any region in this series. All the top 271 // fields still point to bottom, so the intersection between 272 // [bottom,top] and [card_start,card_end] will be empty. Before we 273 // update the top fields, we'll do a storestore to make sure that 274 // no thread sees the update to top before the zeroing of the 275 // object header and the BOT initialization. 276 OrderAccess::storestore(); 277 278 // Now, we will update the top fields of the "continues humongous" 279 // regions except the last one. 280 for (uint i = first; i < last; ++i) { 281 hr = region_at(i); 282 hr->set_top(hr->end()); 283 } 284 285 hr = region_at(last); 286 // If we cannot fit a filler object, we must set top to the end 287 // of the humongous object, otherwise we cannot iterate the heap 288 // and the BOT will not be complete. 289 hr->set_top(hr->end() - words_not_fillable); 290 291 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 292 "obj_top should be in last region"); 293 294 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 295 296 assert(words_not_fillable == 0 || 297 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 298 "Miscalculation in humongous allocation"); 299 300 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 301 302 for (uint i = first; i <= last; ++i) { 303 hr = region_at(i); 304 _humongous_set.add(hr); 305 _hr_printer.alloc(hr); 306 } 307 308 return new_obj; 309 } 310 311 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 312 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 313 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 314 } 315 316 // If could fit into free regions w/o expansion, try. 317 // Otherwise, if can expand, do so. 318 // Otherwise, if using ex regions might help, try with ex given back. 319 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 320 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 321 322 _verifier->verify_region_sets_optional(); 323 324 uint first = G1_NO_HRM_INDEX; 325 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 326 327 if (obj_regions == 1) { 328 // Only one region to allocate, try to use a fast path by directly allocating 329 // from the free lists. Do not try to expand here, we will potentially do that 330 // later. 331 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 332 if (hr != NULL) { 333 first = hr->hrm_index(); 334 } 335 } else { 336 // Policy: Try only empty regions (i.e. already committed first). Maybe we 337 // are lucky enough to find some. 338 first = _hrm.find_contiguous_only_empty(obj_regions); 339 if (first != G1_NO_HRM_INDEX) { 340 _hrm.allocate_free_regions_starting_at(first, obj_regions); 341 } 342 } 343 344 if (first == G1_NO_HRM_INDEX) { 345 // Policy: We could not find enough regions for the humongous object in the 346 // free list. Look through the heap to find a mix of free and uncommitted regions. 347 // If so, try expansion. 348 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 349 if (first != G1_NO_HRM_INDEX) { 350 // We found something. Make sure these regions are committed, i.e. expand 351 // the heap. Alternatively we could do a defragmentation GC. 352 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", 353 word_size * HeapWordSize); 354 355 _hrm.expand_at(first, obj_regions, workers()); 356 g1_policy()->record_new_heap_size(num_regions()); 357 358 #ifdef ASSERT 359 for (uint i = first; i < first + obj_regions; ++i) { 360 HeapRegion* hr = region_at(i); 361 assert(hr->is_free(), "sanity"); 362 assert(hr->is_empty(), "sanity"); 363 assert(is_on_master_free_list(hr), "sanity"); 364 } 365 #endif 366 _hrm.allocate_free_regions_starting_at(first, obj_regions); 367 } else { 368 // Policy: Potentially trigger a defragmentation GC. 369 } 370 } 371 372 HeapWord* result = NULL; 373 if (first != G1_NO_HRM_INDEX) { 374 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size); 375 assert(result != NULL, "it should always return a valid result"); 376 377 // A successful humongous object allocation changes the used space 378 // information of the old generation so we need to recalculate the 379 // sizes and update the jstat counters here. 380 g1mm()->update_sizes(); 381 } 382 383 _verifier->verify_region_sets_optional(); 384 385 return result; 386 } 387 388 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size, 389 size_t requested_size, 390 size_t* actual_size) { 391 assert_heap_not_locked_and_not_at_safepoint(); 392 assert(!is_humongous(requested_size), "we do not allow humongous TLABs"); 393 394 return attempt_allocation(min_size, requested_size, actual_size); 395 } 396 397 HeapWord* 398 G1CollectedHeap::mem_allocate(size_t word_size, 399 bool* gc_overhead_limit_was_exceeded) { 400 assert_heap_not_locked_and_not_at_safepoint(); 401 402 if (is_humongous(word_size)) { 403 return attempt_allocation_humongous(word_size); 404 } 405 size_t dummy = 0; 406 return attempt_allocation(word_size, word_size, &dummy); 407 } 408 409 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 410 ResourceMark rm; // For retrieving the thread names in log messages. 411 412 // Make sure you read the note in attempt_allocation_humongous(). 413 414 assert_heap_not_locked_and_not_at_safepoint(); 415 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 416 "be called for humongous allocation requests"); 417 418 // We should only get here after the first-level allocation attempt 419 // (attempt_allocation()) failed to allocate. 420 421 // We will loop until a) we manage to successfully perform the 422 // allocation or b) we successfully schedule a collection which 423 // fails to perform the allocation. b) is the only case when we'll 424 // return NULL. 425 HeapWord* result = NULL; 426 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 427 bool should_try_gc; 428 uint gc_count_before; 429 430 { 431 MutexLockerEx x(Heap_lock); 432 result = _allocator->attempt_allocation_locked(word_size); 433 if (result != NULL) { 434 return result; 435 } 436 437 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 438 // This is different to when only GCLocker::needs_gc() is set: try to avoid 439 // waiting because the GCLocker is active to not wait too long. 440 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) { 441 // No need for an ergo message here, can_expand_young_list() does this when 442 // it returns true. 443 result = _allocator->attempt_allocation_force(word_size); 444 if (result != NULL) { 445 return result; 446 } 447 } 448 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 449 // the GCLocker initiated GC has been performed and then retry. This includes 450 // the case when the GC Locker is not active but has not been performed. 451 should_try_gc = !GCLocker::needs_gc(); 452 // Read the GC count while still holding the Heap_lock. 453 gc_count_before = total_collections(); 454 } 455 456 if (should_try_gc) { 457 bool succeeded; 458 result = do_collection_pause(word_size, gc_count_before, &succeeded, 459 GCCause::_g1_inc_collection_pause); 460 if (result != NULL) { 461 assert(succeeded, "only way to get back a non-NULL result"); 462 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 463 Thread::current()->name(), p2i(result)); 464 return result; 465 } 466 467 if (succeeded) { 468 // We successfully scheduled a collection which failed to allocate. No 469 // point in trying to allocate further. We'll just return NULL. 470 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 471 SIZE_FORMAT " words", Thread::current()->name(), word_size); 472 return NULL; 473 } 474 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 475 Thread::current()->name(), word_size); 476 } else { 477 // Failed to schedule a collection. 478 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 479 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 480 SIZE_FORMAT " words", Thread::current()->name(), word_size); 481 return NULL; 482 } 483 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 484 // The GCLocker is either active or the GCLocker initiated 485 // GC has not yet been performed. Stall until it is and 486 // then retry the allocation. 487 GCLocker::stall_until_clear(); 488 gclocker_retry_count += 1; 489 } 490 491 // We can reach here if we were unsuccessful in scheduling a 492 // collection (because another thread beat us to it) or if we were 493 // stalled due to the GC locker. In either can we should retry the 494 // allocation attempt in case another thread successfully 495 // performed a collection and reclaimed enough space. We do the 496 // first attempt (without holding the Heap_lock) here and the 497 // follow-on attempt will be at the start of the next loop 498 // iteration (after taking the Heap_lock). 499 size_t dummy = 0; 500 result = _allocator->attempt_allocation(word_size, word_size, &dummy); 501 if (result != NULL) { 502 return result; 503 } 504 505 // Give a warning if we seem to be looping forever. 506 if ((QueuedAllocationWarningCount > 0) && 507 (try_count % QueuedAllocationWarningCount == 0)) { 508 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 509 Thread::current()->name(), try_count, word_size); 510 } 511 } 512 513 ShouldNotReachHere(); 514 return NULL; 515 } 516 517 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 518 assert_at_safepoint_on_vm_thread(); 519 if (_archive_allocator == NULL) { 520 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 521 } 522 } 523 524 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 525 // Allocations in archive regions cannot be of a size that would be considered 526 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 527 // may be different at archive-restore time. 528 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 529 } 530 531 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 532 assert_at_safepoint_on_vm_thread(); 533 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 534 if (is_archive_alloc_too_large(word_size)) { 535 return NULL; 536 } 537 return _archive_allocator->archive_mem_allocate(word_size); 538 } 539 540 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 541 size_t end_alignment_in_bytes) { 542 assert_at_safepoint_on_vm_thread(); 543 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 544 545 // Call complete_archive to do the real work, filling in the MemRegion 546 // array with the archive regions. 547 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 548 delete _archive_allocator; 549 _archive_allocator = NULL; 550 } 551 552 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 553 assert(ranges != NULL, "MemRegion array NULL"); 554 assert(count != 0, "No MemRegions provided"); 555 MemRegion reserved = _hrm.reserved(); 556 for (size_t i = 0; i < count; i++) { 557 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 558 return false; 559 } 560 } 561 return true; 562 } 563 564 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 565 size_t count, 566 bool open) { 567 assert(!is_init_completed(), "Expect to be called at JVM init time"); 568 assert(ranges != NULL, "MemRegion array NULL"); 569 assert(count != 0, "No MemRegions provided"); 570 MutexLockerEx x(Heap_lock); 571 572 MemRegion reserved = _hrm.reserved(); 573 HeapWord* prev_last_addr = NULL; 574 HeapRegion* prev_last_region = NULL; 575 576 // Temporarily disable pretouching of heap pages. This interface is used 577 // when mmap'ing archived heap data in, so pre-touching is wasted. 578 FlagSetting fs(AlwaysPreTouch, false); 579 580 // Enable archive object checking used by G1MarkSweep. We have to let it know 581 // about each archive range, so that objects in those ranges aren't marked. 582 G1ArchiveAllocator::enable_archive_object_check(); 583 584 // For each specified MemRegion range, allocate the corresponding G1 585 // regions and mark them as archive regions. We expect the ranges 586 // in ascending starting address order, without overlap. 587 for (size_t i = 0; i < count; i++) { 588 MemRegion curr_range = ranges[i]; 589 HeapWord* start_address = curr_range.start(); 590 size_t word_size = curr_range.word_size(); 591 HeapWord* last_address = curr_range.last(); 592 size_t commits = 0; 593 594 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 595 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 596 p2i(start_address), p2i(last_address)); 597 guarantee(start_address > prev_last_addr, 598 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 599 p2i(start_address), p2i(prev_last_addr)); 600 prev_last_addr = last_address; 601 602 // Check for ranges that start in the same G1 region in which the previous 603 // range ended, and adjust the start address so we don't try to allocate 604 // the same region again. If the current range is entirely within that 605 // region, skip it, just adjusting the recorded top. 606 HeapRegion* start_region = _hrm.addr_to_region(start_address); 607 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 608 start_address = start_region->end(); 609 if (start_address > last_address) { 610 increase_used(word_size * HeapWordSize); 611 start_region->set_top(last_address + 1); 612 continue; 613 } 614 start_region->set_top(start_address); 615 curr_range = MemRegion(start_address, last_address + 1); 616 start_region = _hrm.addr_to_region(start_address); 617 } 618 619 // Perform the actual region allocation, exiting if it fails. 620 // Then note how much new space we have allocated. 621 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) { 622 return false; 623 } 624 increase_used(word_size * HeapWordSize); 625 if (commits != 0) { 626 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 627 HeapRegion::GrainWords * HeapWordSize * commits); 628 629 } 630 631 // Mark each G1 region touched by the range as archive, add it to 632 // the old set, and set top. 633 HeapRegion* curr_region = _hrm.addr_to_region(start_address); 634 HeapRegion* last_region = _hrm.addr_to_region(last_address); 635 prev_last_region = last_region; 636 637 while (curr_region != NULL) { 638 assert(curr_region->is_empty() && !curr_region->is_pinned(), 639 "Region already in use (index %u)", curr_region->hrm_index()); 640 if (open) { 641 curr_region->set_open_archive(); 642 } else { 643 curr_region->set_closed_archive(); 644 } 645 _hr_printer.alloc(curr_region); 646 _old_set.add(curr_region); 647 HeapWord* top; 648 HeapRegion* next_region; 649 if (curr_region != last_region) { 650 top = curr_region->end(); 651 next_region = _hrm.next_region_in_heap(curr_region); 652 } else { 653 top = last_address + 1; 654 next_region = NULL; 655 } 656 curr_region->set_top(top); 657 curr_region->set_first_dead(top); 658 curr_region->set_end_of_live(top); 659 curr_region = next_region; 660 } 661 662 // Notify mark-sweep of the archive 663 G1ArchiveAllocator::set_range_archive(curr_range, open); 664 } 665 return true; 666 } 667 668 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 669 assert(!is_init_completed(), "Expect to be called at JVM init time"); 670 assert(ranges != NULL, "MemRegion array NULL"); 671 assert(count != 0, "No MemRegions provided"); 672 MemRegion reserved = _hrm.reserved(); 673 HeapWord *prev_last_addr = NULL; 674 HeapRegion* prev_last_region = NULL; 675 676 // For each MemRegion, create filler objects, if needed, in the G1 regions 677 // that contain the address range. The address range actually within the 678 // MemRegion will not be modified. That is assumed to have been initialized 679 // elsewhere, probably via an mmap of archived heap data. 680 MutexLockerEx x(Heap_lock); 681 for (size_t i = 0; i < count; i++) { 682 HeapWord* start_address = ranges[i].start(); 683 HeapWord* last_address = ranges[i].last(); 684 685 assert(reserved.contains(start_address) && reserved.contains(last_address), 686 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 687 p2i(start_address), p2i(last_address)); 688 assert(start_address > prev_last_addr, 689 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 690 p2i(start_address), p2i(prev_last_addr)); 691 692 HeapRegion* start_region = _hrm.addr_to_region(start_address); 693 HeapRegion* last_region = _hrm.addr_to_region(last_address); 694 HeapWord* bottom_address = start_region->bottom(); 695 696 // Check for a range beginning in the same region in which the 697 // previous one ended. 698 if (start_region == prev_last_region) { 699 bottom_address = prev_last_addr + 1; 700 } 701 702 // Verify that the regions were all marked as archive regions by 703 // alloc_archive_regions. 704 HeapRegion* curr_region = start_region; 705 while (curr_region != NULL) { 706 guarantee(curr_region->is_archive(), 707 "Expected archive region at index %u", curr_region->hrm_index()); 708 if (curr_region != last_region) { 709 curr_region = _hrm.next_region_in_heap(curr_region); 710 } else { 711 curr_region = NULL; 712 } 713 } 714 715 prev_last_addr = last_address; 716 prev_last_region = last_region; 717 718 // Fill the memory below the allocated range with dummy object(s), 719 // if the region bottom does not match the range start, or if the previous 720 // range ended within the same G1 region, and there is a gap. 721 if (start_address != bottom_address) { 722 size_t fill_size = pointer_delta(start_address, bottom_address); 723 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 724 increase_used(fill_size * HeapWordSize); 725 } 726 } 727 } 728 729 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size, 730 size_t desired_word_size, 731 size_t* actual_word_size) { 732 assert_heap_not_locked_and_not_at_safepoint(); 733 assert(!is_humongous(desired_word_size), "attempt_allocation() should not " 734 "be called for humongous allocation requests"); 735 736 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size); 737 738 if (result == NULL) { 739 *actual_word_size = desired_word_size; 740 result = attempt_allocation_slow(desired_word_size); 741 } 742 743 assert_heap_not_locked(); 744 if (result != NULL) { 745 assert(*actual_word_size != 0, "Actual size must have been set here"); 746 dirty_young_block(result, *actual_word_size); 747 } else { 748 *actual_word_size = 0; 749 } 750 751 return result; 752 } 753 754 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 755 assert(!is_init_completed(), "Expect to be called at JVM init time"); 756 assert(ranges != NULL, "MemRegion array NULL"); 757 assert(count != 0, "No MemRegions provided"); 758 MemRegion reserved = _hrm.reserved(); 759 HeapWord* prev_last_addr = NULL; 760 HeapRegion* prev_last_region = NULL; 761 size_t size_used = 0; 762 size_t uncommitted_regions = 0; 763 764 // For each Memregion, free the G1 regions that constitute it, and 765 // notify mark-sweep that the range is no longer to be considered 'archive.' 766 MutexLockerEx x(Heap_lock); 767 for (size_t i = 0; i < count; i++) { 768 HeapWord* start_address = ranges[i].start(); 769 HeapWord* last_address = ranges[i].last(); 770 771 assert(reserved.contains(start_address) && reserved.contains(last_address), 772 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 773 p2i(start_address), p2i(last_address)); 774 assert(start_address > prev_last_addr, 775 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 776 p2i(start_address), p2i(prev_last_addr)); 777 size_used += ranges[i].byte_size(); 778 prev_last_addr = last_address; 779 780 HeapRegion* start_region = _hrm.addr_to_region(start_address); 781 HeapRegion* last_region = _hrm.addr_to_region(last_address); 782 783 // Check for ranges that start in the same G1 region in which the previous 784 // range ended, and adjust the start address so we don't try to free 785 // the same region again. If the current range is entirely within that 786 // region, skip it. 787 if (start_region == prev_last_region) { 788 start_address = start_region->end(); 789 if (start_address > last_address) { 790 continue; 791 } 792 start_region = _hrm.addr_to_region(start_address); 793 } 794 prev_last_region = last_region; 795 796 // After verifying that each region was marked as an archive region by 797 // alloc_archive_regions, set it free and empty and uncommit it. 798 HeapRegion* curr_region = start_region; 799 while (curr_region != NULL) { 800 guarantee(curr_region->is_archive(), 801 "Expected archive region at index %u", curr_region->hrm_index()); 802 uint curr_index = curr_region->hrm_index(); 803 _old_set.remove(curr_region); 804 curr_region->set_free(); 805 curr_region->set_top(curr_region->bottom()); 806 if (curr_region != last_region) { 807 curr_region = _hrm.next_region_in_heap(curr_region); 808 } else { 809 curr_region = NULL; 810 } 811 _hrm.shrink_at(curr_index, 1); 812 uncommitted_regions++; 813 } 814 815 // Notify mark-sweep that this is no longer an archive range. 816 G1ArchiveAllocator::set_range_archive(ranges[i], false); 817 } 818 819 if (uncommitted_regions != 0) { 820 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 821 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 822 } 823 decrease_used(size_used); 824 } 825 826 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 827 ResourceMark rm; // For retrieving the thread names in log messages. 828 829 // The structure of this method has a lot of similarities to 830 // attempt_allocation_slow(). The reason these two were not merged 831 // into a single one is that such a method would require several "if 832 // allocation is not humongous do this, otherwise do that" 833 // conditional paths which would obscure its flow. In fact, an early 834 // version of this code did use a unified method which was harder to 835 // follow and, as a result, it had subtle bugs that were hard to 836 // track down. So keeping these two methods separate allows each to 837 // be more readable. It will be good to keep these two in sync as 838 // much as possible. 839 840 assert_heap_not_locked_and_not_at_safepoint(); 841 assert(is_humongous(word_size), "attempt_allocation_humongous() " 842 "should only be called for humongous allocations"); 843 844 // Humongous objects can exhaust the heap quickly, so we should check if we 845 // need to start a marking cycle at each humongous object allocation. We do 846 // the check before we do the actual allocation. The reason for doing it 847 // before the allocation is that we avoid having to keep track of the newly 848 // allocated memory while we do a GC. 849 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 850 word_size)) { 851 collect(GCCause::_g1_humongous_allocation); 852 } 853 854 // We will loop until a) we manage to successfully perform the 855 // allocation or b) we successfully schedule a collection which 856 // fails to perform the allocation. b) is the only case when we'll 857 // return NULL. 858 HeapWord* result = NULL; 859 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 860 bool should_try_gc; 861 uint gc_count_before; 862 863 864 { 865 MutexLockerEx x(Heap_lock); 866 867 // Given that humongous objects are not allocated in young 868 // regions, we'll first try to do the allocation without doing a 869 // collection hoping that there's enough space in the heap. 870 result = humongous_obj_allocate(word_size); 871 if (result != NULL) { 872 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 873 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 874 return result; 875 } 876 877 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 878 // the GCLocker initiated GC has been performed and then retry. This includes 879 // the case when the GC Locker is not active but has not been performed. 880 should_try_gc = !GCLocker::needs_gc(); 881 // Read the GC count while still holding the Heap_lock. 882 gc_count_before = total_collections(); 883 } 884 885 if (should_try_gc) { 886 bool succeeded; 887 result = do_collection_pause(word_size, gc_count_before, &succeeded, 888 GCCause::_g1_humongous_allocation); 889 if (result != NULL) { 890 assert(succeeded, "only way to get back a non-NULL result"); 891 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 892 Thread::current()->name(), p2i(result)); 893 return result; 894 } 895 896 if (succeeded) { 897 // We successfully scheduled a collection which failed to allocate. No 898 // point in trying to allocate further. We'll just return NULL. 899 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 900 SIZE_FORMAT " words", Thread::current()->name(), word_size); 901 return NULL; 902 } 903 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 904 Thread::current()->name(), word_size); 905 } else { 906 // Failed to schedule a collection. 907 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 908 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 909 SIZE_FORMAT " words", Thread::current()->name(), word_size); 910 return NULL; 911 } 912 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 913 // The GCLocker is either active or the GCLocker initiated 914 // GC has not yet been performed. Stall until it is and 915 // then retry the allocation. 916 GCLocker::stall_until_clear(); 917 gclocker_retry_count += 1; 918 } 919 920 921 // We can reach here if we were unsuccessful in scheduling a 922 // collection (because another thread beat us to it) or if we were 923 // stalled due to the GC locker. In either can we should retry the 924 // allocation attempt in case another thread successfully 925 // performed a collection and reclaimed enough space. 926 // Humongous object allocation always needs a lock, so we wait for the retry 927 // in the next iteration of the loop, unlike for the regular iteration case. 928 // Give a warning if we seem to be looping forever. 929 930 if ((QueuedAllocationWarningCount > 0) && 931 (try_count % QueuedAllocationWarningCount == 0)) { 932 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 933 Thread::current()->name(), try_count, word_size); 934 } 935 } 936 937 ShouldNotReachHere(); 938 return NULL; 939 } 940 941 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 942 bool expect_null_mutator_alloc_region) { 943 assert_at_safepoint_on_vm_thread(); 944 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 945 "the current alloc region was unexpectedly found to be non-NULL"); 946 947 if (!is_humongous(word_size)) { 948 return _allocator->attempt_allocation_locked(word_size); 949 } else { 950 HeapWord* result = humongous_obj_allocate(word_size); 951 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 952 collector_state()->set_initiate_conc_mark_if_possible(true); 953 } 954 return result; 955 } 956 957 ShouldNotReachHere(); 958 } 959 960 class PostCompactionPrinterClosure: public HeapRegionClosure { 961 private: 962 G1HRPrinter* _hr_printer; 963 public: 964 bool do_heap_region(HeapRegion* hr) { 965 assert(!hr->is_young(), "not expecting to find young regions"); 966 _hr_printer->post_compaction(hr); 967 return false; 968 } 969 970 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 971 : _hr_printer(hr_printer) { } 972 }; 973 974 void G1CollectedHeap::print_hrm_post_compaction() { 975 if (_hr_printer.is_active()) { 976 PostCompactionPrinterClosure cl(hr_printer()); 977 heap_region_iterate(&cl); 978 } 979 } 980 981 void G1CollectedHeap::abort_concurrent_cycle() { 982 // If we start the compaction before the CM threads finish 983 // scanning the root regions we might trip them over as we'll 984 // be moving objects / updating references. So let's wait until 985 // they are done. By telling them to abort, they should complete 986 // early. 987 _cm->root_regions()->abort(); 988 _cm->root_regions()->wait_until_scan_finished(); 989 990 // Disable discovery and empty the discovered lists 991 // for the CM ref processor. 992 _ref_processor_cm->disable_discovery(); 993 _ref_processor_cm->abandon_partial_discovery(); 994 _ref_processor_cm->verify_no_references_recorded(); 995 996 // Abandon current iterations of concurrent marking and concurrent 997 // refinement, if any are in progress. 998 concurrent_mark()->concurrent_cycle_abort(); 999 } 1000 1001 void G1CollectedHeap::prepare_heap_for_full_collection() { 1002 // Make sure we'll choose a new allocation region afterwards. 1003 _allocator->release_mutator_alloc_region(); 1004 _allocator->abandon_gc_alloc_regions(); 1005 g1_rem_set()->cleanupHRRS(); 1006 1007 // We may have added regions to the current incremental collection 1008 // set between the last GC or pause and now. We need to clear the 1009 // incremental collection set and then start rebuilding it afresh 1010 // after this full GC. 1011 abandon_collection_set(collection_set()); 1012 1013 tear_down_region_sets(false /* free_list_only */); 1014 } 1015 1016 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1017 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1018 assert(used() == recalculate_used(), "Should be equal"); 1019 _verifier->verify_region_sets_optional(); 1020 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1021 _verifier->check_bitmaps("Full GC Start"); 1022 } 1023 1024 void G1CollectedHeap::prepare_heap_for_mutators() { 1025 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1026 ClassLoaderDataGraph::purge(); 1027 MetaspaceUtils::verify_metrics(); 1028 1029 // Prepare heap for normal collections. 1030 assert(num_free_regions() == 0, "we should not have added any free regions"); 1031 rebuild_region_sets(false /* free_list_only */); 1032 abort_refinement(); 1033 resize_if_necessary_after_full_collection(); 1034 1035 // Rebuild the strong code root lists for each region 1036 rebuild_strong_code_roots(); 1037 1038 // Start a new incremental collection set for the next pause 1039 start_new_collection_set(); 1040 1041 _allocator->init_mutator_alloc_region(); 1042 1043 // Post collection state updates. 1044 MetaspaceGC::compute_new_size(); 1045 } 1046 1047 void G1CollectedHeap::abort_refinement() { 1048 if (_hot_card_cache->use_cache()) { 1049 _hot_card_cache->reset_hot_cache(); 1050 } 1051 1052 // Discard all remembered set updates. 1053 G1BarrierSet::dirty_card_queue_set().abandon_logs(); 1054 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1055 } 1056 1057 void G1CollectedHeap::verify_after_full_collection() { 1058 _hrm.verify_optional(); 1059 _verifier->verify_region_sets_optional(); 1060 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1061 // Clear the previous marking bitmap, if needed for bitmap verification. 1062 // Note we cannot do this when we clear the next marking bitmap in 1063 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1064 // objects marked during a full GC against the previous bitmap. 1065 // But we need to clear it before calling check_bitmaps below since 1066 // the full GC has compacted objects and updated TAMS but not updated 1067 // the prev bitmap. 1068 if (G1VerifyBitmaps) { 1069 GCTraceTime(Debug, gc)("Clear Bitmap for Verification"); 1070 _cm->clear_prev_bitmap(workers()); 1071 } 1072 _verifier->check_bitmaps("Full GC End"); 1073 1074 // At this point there should be no regions in the 1075 // entire heap tagged as young. 1076 assert(check_young_list_empty(), "young list should be empty at this point"); 1077 1078 // Note: since we've just done a full GC, concurrent 1079 // marking is no longer active. Therefore we need not 1080 // re-enable reference discovery for the CM ref processor. 1081 // That will be done at the start of the next marking cycle. 1082 // We also know that the STW processor should no longer 1083 // discover any new references. 1084 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1085 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1086 _ref_processor_stw->verify_no_references_recorded(); 1087 _ref_processor_cm->verify_no_references_recorded(); 1088 } 1089 1090 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1091 // Post collection logging. 1092 // We should do this after we potentially resize the heap so 1093 // that all the COMMIT / UNCOMMIT events are generated before 1094 // the compaction events. 1095 print_hrm_post_compaction(); 1096 heap_transition->print(); 1097 print_heap_after_gc(); 1098 print_heap_regions(); 1099 #ifdef TRACESPINNING 1100 ParallelTaskTerminator::print_termination_counts(); 1101 #endif 1102 } 1103 1104 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1105 bool clear_all_soft_refs) { 1106 assert_at_safepoint_on_vm_thread(); 1107 1108 if (GCLocker::check_active_before_gc()) { 1109 // Full GC was not completed. 1110 return false; 1111 } 1112 1113 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1114 soft_ref_policy()->should_clear_all_soft_refs(); 1115 1116 G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs); 1117 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1118 1119 collector.prepare_collection(); 1120 collector.collect(); 1121 collector.complete_collection(); 1122 1123 // Full collection was successfully completed. 1124 return true; 1125 } 1126 1127 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1128 // Currently, there is no facility in the do_full_collection(bool) API to notify 1129 // the caller that the collection did not succeed (e.g., because it was locked 1130 // out by the GC locker). So, right now, we'll ignore the return value. 1131 bool dummy = do_full_collection(true, /* explicit_gc */ 1132 clear_all_soft_refs); 1133 } 1134 1135 void G1CollectedHeap::resize_if_necessary_after_full_collection() { 1136 // Capacity, free and used after the GC counted as full regions to 1137 // include the waste in the following calculations. 1138 const size_t capacity_after_gc = capacity(); 1139 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1140 1141 // This is enforced in arguments.cpp. 1142 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1143 "otherwise the code below doesn't make sense"); 1144 1145 // We don't have floating point command-line arguments 1146 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1147 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1148 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1149 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1150 1151 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1152 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1153 1154 // We have to be careful here as these two calculations can overflow 1155 // 32-bit size_t's. 1156 double used_after_gc_d = (double) used_after_gc; 1157 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1158 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1159 1160 // Let's make sure that they are both under the max heap size, which 1161 // by default will make them fit into a size_t. 1162 double desired_capacity_upper_bound = (double) max_heap_size; 1163 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1164 desired_capacity_upper_bound); 1165 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1166 desired_capacity_upper_bound); 1167 1168 // We can now safely turn them into size_t's. 1169 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1170 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1171 1172 // This assert only makes sense here, before we adjust them 1173 // with respect to the min and max heap size. 1174 assert(minimum_desired_capacity <= maximum_desired_capacity, 1175 "minimum_desired_capacity = " SIZE_FORMAT ", " 1176 "maximum_desired_capacity = " SIZE_FORMAT, 1177 minimum_desired_capacity, maximum_desired_capacity); 1178 1179 // Should not be greater than the heap max size. No need to adjust 1180 // it with respect to the heap min size as it's a lower bound (i.e., 1181 // we'll try to make the capacity larger than it, not smaller). 1182 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1183 // Should not be less than the heap min size. No need to adjust it 1184 // with respect to the heap max size as it's an upper bound (i.e., 1185 // we'll try to make the capacity smaller than it, not greater). 1186 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1187 1188 if (capacity_after_gc < minimum_desired_capacity) { 1189 // Don't expand unless it's significant 1190 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1191 1192 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). " 1193 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1194 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1195 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1196 1197 expand(expand_bytes, _workers); 1198 1199 // No expansion, now see if we want to shrink 1200 } else if (capacity_after_gc > maximum_desired_capacity) { 1201 // Capacity too large, compute shrinking size 1202 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1203 1204 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). " 1205 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1206 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1207 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1208 1209 shrink(shrink_bytes); 1210 } 1211 } 1212 1213 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1214 bool do_gc, 1215 bool clear_all_soft_refs, 1216 bool expect_null_mutator_alloc_region, 1217 bool* gc_succeeded) { 1218 *gc_succeeded = true; 1219 // Let's attempt the allocation first. 1220 HeapWord* result = 1221 attempt_allocation_at_safepoint(word_size, 1222 expect_null_mutator_alloc_region); 1223 if (result != NULL) { 1224 return result; 1225 } 1226 1227 // In a G1 heap, we're supposed to keep allocation from failing by 1228 // incremental pauses. Therefore, at least for now, we'll favor 1229 // expansion over collection. (This might change in the future if we can 1230 // do something smarter than full collection to satisfy a failed alloc.) 1231 result = expand_and_allocate(word_size); 1232 if (result != NULL) { 1233 return result; 1234 } 1235 1236 if (do_gc) { 1237 // Expansion didn't work, we'll try to do a Full GC. 1238 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1239 clear_all_soft_refs); 1240 } 1241 1242 return NULL; 1243 } 1244 1245 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1246 bool* succeeded) { 1247 assert_at_safepoint_on_vm_thread(); 1248 1249 // Attempts to allocate followed by Full GC. 1250 HeapWord* result = 1251 satisfy_failed_allocation_helper(word_size, 1252 true, /* do_gc */ 1253 false, /* clear_all_soft_refs */ 1254 false, /* expect_null_mutator_alloc_region */ 1255 succeeded); 1256 1257 if (result != NULL || !*succeeded) { 1258 return result; 1259 } 1260 1261 // Attempts to allocate followed by Full GC that will collect all soft references. 1262 result = satisfy_failed_allocation_helper(word_size, 1263 true, /* do_gc */ 1264 true, /* clear_all_soft_refs */ 1265 true, /* expect_null_mutator_alloc_region */ 1266 succeeded); 1267 1268 if (result != NULL || !*succeeded) { 1269 return result; 1270 } 1271 1272 // Attempts to allocate, no GC 1273 result = satisfy_failed_allocation_helper(word_size, 1274 false, /* do_gc */ 1275 false, /* clear_all_soft_refs */ 1276 true, /* expect_null_mutator_alloc_region */ 1277 succeeded); 1278 1279 if (result != NULL) { 1280 return result; 1281 } 1282 1283 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1284 "Flag should have been handled and cleared prior to this point"); 1285 1286 // What else? We might try synchronous finalization later. If the total 1287 // space available is large enough for the allocation, then a more 1288 // complete compaction phase than we've tried so far might be 1289 // appropriate. 1290 return NULL; 1291 } 1292 1293 // Attempting to expand the heap sufficiently 1294 // to support an allocation of the given "word_size". If 1295 // successful, perform the allocation and return the address of the 1296 // allocated block, or else "NULL". 1297 1298 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1299 assert_at_safepoint_on_vm_thread(); 1300 1301 _verifier->verify_region_sets_optional(); 1302 1303 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1304 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1305 word_size * HeapWordSize); 1306 1307 1308 if (expand(expand_bytes, _workers)) { 1309 _hrm.verify_optional(); 1310 _verifier->verify_region_sets_optional(); 1311 return attempt_allocation_at_safepoint(word_size, 1312 false /* expect_null_mutator_alloc_region */); 1313 } 1314 return NULL; 1315 } 1316 1317 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1318 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1319 aligned_expand_bytes = align_up(aligned_expand_bytes, 1320 HeapRegion::GrainBytes); 1321 1322 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1323 expand_bytes, aligned_expand_bytes); 1324 1325 if (is_maximal_no_gc()) { 1326 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1327 return false; 1328 } 1329 1330 double expand_heap_start_time_sec = os::elapsedTime(); 1331 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1332 assert(regions_to_expand > 0, "Must expand by at least one region"); 1333 1334 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers); 1335 if (expand_time_ms != NULL) { 1336 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1337 } 1338 1339 if (expanded_by > 0) { 1340 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1341 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1342 g1_policy()->record_new_heap_size(num_regions()); 1343 } else { 1344 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1345 1346 // The expansion of the virtual storage space was unsuccessful. 1347 // Let's see if it was because we ran out of swap. 1348 if (G1ExitOnExpansionFailure && 1349 _hrm.available() >= regions_to_expand) { 1350 // We had head room... 1351 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1352 } 1353 } 1354 return regions_to_expand > 0; 1355 } 1356 1357 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1358 size_t aligned_shrink_bytes = 1359 ReservedSpace::page_align_size_down(shrink_bytes); 1360 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1361 HeapRegion::GrainBytes); 1362 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1363 1364 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1365 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1366 1367 1368 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", 1369 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1370 if (num_regions_removed > 0) { 1371 g1_policy()->record_new_heap_size(num_regions()); 1372 } else { 1373 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1374 } 1375 } 1376 1377 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1378 _verifier->verify_region_sets_optional(); 1379 1380 // We should only reach here at the end of a Full GC which means we 1381 // should not not be holding to any GC alloc regions. The method 1382 // below will make sure of that and do any remaining clean up. 1383 _allocator->abandon_gc_alloc_regions(); 1384 1385 // Instead of tearing down / rebuilding the free lists here, we 1386 // could instead use the remove_all_pending() method on free_list to 1387 // remove only the ones that we need to remove. 1388 tear_down_region_sets(true /* free_list_only */); 1389 shrink_helper(shrink_bytes); 1390 rebuild_region_sets(true /* free_list_only */); 1391 1392 _hrm.verify_optional(); 1393 _verifier->verify_region_sets_optional(); 1394 } 1395 1396 // Public methods. 1397 1398 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) : 1399 CollectedHeap(), 1400 _young_gen_sampling_thread(NULL), 1401 _collector_policy(collector_policy), 1402 _soft_ref_policy(), 1403 _card_table(NULL), 1404 _memory_manager("G1 Young Generation", "end of minor GC"), 1405 _full_gc_memory_manager("G1 Old Generation", "end of major GC"), 1406 _eden_pool(NULL), 1407 _survivor_pool(NULL), 1408 _old_pool(NULL), 1409 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1410 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1411 _g1_policy(new G1Policy(_gc_timer_stw)), 1412 _collection_set(this, _g1_policy), 1413 _dirty_card_queue_set(false), 1414 _ref_processor_stw(NULL), 1415 _is_alive_closure_stw(this), 1416 _is_subject_to_discovery_stw(this), 1417 _ref_processor_cm(NULL), 1418 _is_alive_closure_cm(this), 1419 _is_subject_to_discovery_cm(this), 1420 _bot(NULL), 1421 _hot_card_cache(NULL), 1422 _g1_rem_set(NULL), 1423 _cr(NULL), 1424 _g1mm(NULL), 1425 _preserved_marks_set(true /* in_c_heap */), 1426 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1427 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1428 _humongous_reclaim_candidates(), 1429 _has_humongous_reclaim_candidates(false), 1430 _archive_allocator(NULL), 1431 _summary_bytes_used(0), 1432 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1433 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1434 _expand_heap_after_alloc_failure(true), 1435 _old_marking_cycles_started(0), 1436 _old_marking_cycles_completed(0), 1437 _in_cset_fast_test() { 1438 1439 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1440 /* are_GC_task_threads */true, 1441 /* are_ConcurrentGC_threads */false); 1442 _workers->initialize_workers(); 1443 _verifier = new G1HeapVerifier(this); 1444 1445 _allocator = new G1Allocator(this); 1446 1447 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics()); 1448 1449 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1450 1451 // Override the default _filler_array_max_size so that no humongous filler 1452 // objects are created. 1453 _filler_array_max_size = _humongous_object_threshold_in_words; 1454 1455 uint n_queues = ParallelGCThreads; 1456 _task_queues = new RefToScanQueueSet(n_queues); 1457 1458 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1459 1460 for (uint i = 0; i < n_queues; i++) { 1461 RefToScanQueue* q = new RefToScanQueue(); 1462 q->initialize(); 1463 _task_queues->register_queue(i, q); 1464 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1465 } 1466 1467 // Initialize the G1EvacuationFailureALot counters and flags. 1468 NOT_PRODUCT(reset_evacuation_should_fail();) 1469 1470 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1471 } 1472 1473 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1474 size_t size, 1475 size_t translation_factor) { 1476 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1477 // Allocate a new reserved space, preferring to use large pages. 1478 ReservedSpace rs(size, preferred_page_size); 1479 G1RegionToSpaceMapper* result = 1480 G1RegionToSpaceMapper::create_mapper(rs, 1481 size, 1482 rs.alignment(), 1483 HeapRegion::GrainBytes, 1484 translation_factor, 1485 mtGC); 1486 1487 os::trace_page_sizes_for_requested_size(description, 1488 size, 1489 preferred_page_size, 1490 rs.alignment(), 1491 rs.base(), 1492 rs.size()); 1493 1494 return result; 1495 } 1496 1497 jint G1CollectedHeap::initialize_concurrent_refinement() { 1498 jint ecode = JNI_OK; 1499 _cr = G1ConcurrentRefine::create(&ecode); 1500 return ecode; 1501 } 1502 1503 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1504 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1505 if (_young_gen_sampling_thread->osthread() == NULL) { 1506 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1507 return JNI_ENOMEM; 1508 } 1509 return JNI_OK; 1510 } 1511 1512 jint G1CollectedHeap::initialize() { 1513 os::enable_vtime(); 1514 1515 // Necessary to satisfy locking discipline assertions. 1516 1517 MutexLocker x(Heap_lock); 1518 1519 // While there are no constraints in the GC code that HeapWordSize 1520 // be any particular value, there are multiple other areas in the 1521 // system which believe this to be true (e.g. oop->object_size in some 1522 // cases incorrectly returns the size in wordSize units rather than 1523 // HeapWordSize). 1524 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1525 1526 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1527 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1528 size_t heap_alignment = collector_policy()->heap_alignment(); 1529 1530 // Ensure that the sizes are properly aligned. 1531 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1532 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1533 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1534 1535 // Reserve the maximum. 1536 1537 // When compressed oops are enabled, the preferred heap base 1538 // is calculated by subtracting the requested size from the 1539 // 32Gb boundary and using the result as the base address for 1540 // heap reservation. If the requested size is not aligned to 1541 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1542 // into the ReservedHeapSpace constructor) then the actual 1543 // base of the reserved heap may end up differing from the 1544 // address that was requested (i.e. the preferred heap base). 1545 // If this happens then we could end up using a non-optimal 1546 // compressed oops mode. 1547 1548 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1549 heap_alignment); 1550 1551 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1552 1553 // Create the barrier set for the entire reserved region. 1554 G1CardTable* ct = new G1CardTable(reserved_region()); 1555 ct->initialize(); 1556 G1BarrierSet* bs = new G1BarrierSet(ct); 1557 bs->initialize(); 1558 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1559 BarrierSet::set_barrier_set(bs); 1560 _card_table = ct; 1561 1562 // Create the hot card cache. 1563 _hot_card_cache = new G1HotCardCache(this); 1564 1565 // Carve out the G1 part of the heap. 1566 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1567 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 1568 G1RegionToSpaceMapper* heap_storage = 1569 G1RegionToSpaceMapper::create_mapper(g1_rs, 1570 g1_rs.size(), 1571 page_size, 1572 HeapRegion::GrainBytes, 1573 1, 1574 mtJavaHeap); 1575 os::trace_page_sizes("Heap", 1576 collector_policy()->min_heap_byte_size(), 1577 max_byte_size, 1578 page_size, 1579 heap_rs.base(), 1580 heap_rs.size()); 1581 heap_storage->set_mapping_changed_listener(&_listener); 1582 1583 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1584 G1RegionToSpaceMapper* bot_storage = 1585 create_aux_memory_mapper("Block Offset Table", 1586 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1587 G1BlockOffsetTable::heap_map_factor()); 1588 1589 G1RegionToSpaceMapper* cardtable_storage = 1590 create_aux_memory_mapper("Card Table", 1591 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1592 G1CardTable::heap_map_factor()); 1593 1594 G1RegionToSpaceMapper* card_counts_storage = 1595 create_aux_memory_mapper("Card Counts Table", 1596 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1597 G1CardCounts::heap_map_factor()); 1598 1599 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1600 G1RegionToSpaceMapper* prev_bitmap_storage = 1601 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1602 G1RegionToSpaceMapper* next_bitmap_storage = 1603 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1604 1605 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1606 _card_table->initialize(cardtable_storage); 1607 // Do later initialization work for concurrent refinement. 1608 _hot_card_cache->initialize(card_counts_storage); 1609 1610 // 6843694 - ensure that the maximum region index can fit 1611 // in the remembered set structures. 1612 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1613 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1614 1615 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1616 // start within the first card. 1617 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1618 // Also create a G1 rem set. 1619 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1620 _g1_rem_set->initialize(max_capacity(), max_regions()); 1621 1622 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1623 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1624 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1625 "too many cards per region"); 1626 1627 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1628 1629 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1630 1631 { 1632 HeapWord* start = _hrm.reserved().start(); 1633 HeapWord* end = _hrm.reserved().end(); 1634 size_t granularity = HeapRegion::GrainBytes; 1635 1636 _in_cset_fast_test.initialize(start, end, granularity); 1637 _humongous_reclaim_candidates.initialize(start, end, granularity); 1638 } 1639 1640 // Create the G1ConcurrentMark data structure and thread. 1641 // (Must do this late, so that "max_regions" is defined.) 1642 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1643 if (_cm == NULL || !_cm->completed_initialization()) { 1644 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1645 return JNI_ENOMEM; 1646 } 1647 _cm_thread = _cm->cm_thread(); 1648 1649 // Now expand into the initial heap size. 1650 if (!expand(init_byte_size, _workers)) { 1651 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1652 return JNI_ENOMEM; 1653 } 1654 1655 // Perform any initialization actions delegated to the policy. 1656 g1_policy()->init(this, &_collection_set); 1657 1658 G1BarrierSet::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 1659 SATB_Q_FL_lock, 1660 G1SATBProcessCompletedThreshold, 1661 Shared_SATB_Q_lock); 1662 1663 jint ecode = initialize_concurrent_refinement(); 1664 if (ecode != JNI_OK) { 1665 return ecode; 1666 } 1667 1668 ecode = initialize_young_gen_sampling_thread(); 1669 if (ecode != JNI_OK) { 1670 return ecode; 1671 } 1672 1673 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1674 DirtyCardQ_FL_lock, 1675 (int)concurrent_refine()->yellow_zone(), 1676 (int)concurrent_refine()->red_zone(), 1677 Shared_DirtyCardQ_lock, 1678 NULL, // fl_owner 1679 true); // init_free_ids 1680 1681 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1682 DirtyCardQ_FL_lock, 1683 -1, // never trigger processing 1684 -1, // no limit on length 1685 Shared_DirtyCardQ_lock, 1686 &G1BarrierSet::dirty_card_queue_set()); 1687 1688 // Here we allocate the dummy HeapRegion that is required by the 1689 // G1AllocRegion class. 1690 HeapRegion* dummy_region = _hrm.get_dummy_region(); 1691 1692 // We'll re-use the same region whether the alloc region will 1693 // require BOT updates or not and, if it doesn't, then a non-young 1694 // region will complain that it cannot support allocations without 1695 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1696 dummy_region->set_eden(); 1697 // Make sure it's full. 1698 dummy_region->set_top(dummy_region->end()); 1699 G1AllocRegion::setup(this, dummy_region); 1700 1701 _allocator->init_mutator_alloc_region(); 1702 1703 // Do create of the monitoring and management support so that 1704 // values in the heap have been properly initialized. 1705 _g1mm = new G1MonitoringSupport(this); 1706 1707 G1StringDedup::initialize(); 1708 1709 _preserved_marks_set.init(ParallelGCThreads); 1710 1711 _collection_set.initialize(max_regions()); 1712 1713 return JNI_OK; 1714 } 1715 1716 void G1CollectedHeap::initialize_serviceability() { 1717 _eden_pool = new G1EdenPool(this); 1718 _survivor_pool = new G1SurvivorPool(this); 1719 _old_pool = new G1OldGenPool(this); 1720 1721 _full_gc_memory_manager.add_pool(_eden_pool); 1722 _full_gc_memory_manager.add_pool(_survivor_pool); 1723 _full_gc_memory_manager.add_pool(_old_pool); 1724 1725 _memory_manager.add_pool(_eden_pool); 1726 _memory_manager.add_pool(_survivor_pool); 1727 1728 } 1729 1730 void G1CollectedHeap::stop() { 1731 // Stop all concurrent threads. We do this to make sure these threads 1732 // do not continue to execute and access resources (e.g. logging) 1733 // that are destroyed during shutdown. 1734 _cr->stop(); 1735 _young_gen_sampling_thread->stop(); 1736 _cm_thread->stop(); 1737 if (G1StringDedup::is_enabled()) { 1738 G1StringDedup::stop(); 1739 } 1740 } 1741 1742 void G1CollectedHeap::safepoint_synchronize_begin() { 1743 SuspendibleThreadSet::synchronize(); 1744 } 1745 1746 void G1CollectedHeap::safepoint_synchronize_end() { 1747 SuspendibleThreadSet::desynchronize(); 1748 } 1749 1750 size_t G1CollectedHeap::conservative_max_heap_alignment() { 1751 return HeapRegion::max_region_size(); 1752 } 1753 1754 void G1CollectedHeap::post_initialize() { 1755 CollectedHeap::post_initialize(); 1756 ref_processing_init(); 1757 } 1758 1759 void G1CollectedHeap::ref_processing_init() { 1760 // Reference processing in G1 currently works as follows: 1761 // 1762 // * There are two reference processor instances. One is 1763 // used to record and process discovered references 1764 // during concurrent marking; the other is used to 1765 // record and process references during STW pauses 1766 // (both full and incremental). 1767 // * Both ref processors need to 'span' the entire heap as 1768 // the regions in the collection set may be dotted around. 1769 // 1770 // * For the concurrent marking ref processor: 1771 // * Reference discovery is enabled at initial marking. 1772 // * Reference discovery is disabled and the discovered 1773 // references processed etc during remarking. 1774 // * Reference discovery is MT (see below). 1775 // * Reference discovery requires a barrier (see below). 1776 // * Reference processing may or may not be MT 1777 // (depending on the value of ParallelRefProcEnabled 1778 // and ParallelGCThreads). 1779 // * A full GC disables reference discovery by the CM 1780 // ref processor and abandons any entries on it's 1781 // discovered lists. 1782 // 1783 // * For the STW processor: 1784 // * Non MT discovery is enabled at the start of a full GC. 1785 // * Processing and enqueueing during a full GC is non-MT. 1786 // * During a full GC, references are processed after marking. 1787 // 1788 // * Discovery (may or may not be MT) is enabled at the start 1789 // of an incremental evacuation pause. 1790 // * References are processed near the end of a STW evacuation pause. 1791 // * For both types of GC: 1792 // * Discovery is atomic - i.e. not concurrent. 1793 // * Reference discovery will not need a barrier. 1794 1795 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1796 1797 // Concurrent Mark ref processor 1798 _ref_processor_cm = 1799 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1800 mt_processing, // mt processing 1801 ParallelGCThreads, // degree of mt processing 1802 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1803 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1804 false, // Reference discovery is not atomic 1805 &_is_alive_closure_cm); // is alive closure 1806 1807 // STW ref processor 1808 _ref_processor_stw = 1809 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1810 mt_processing, // mt processing 1811 ParallelGCThreads, // degree of mt processing 1812 (ParallelGCThreads > 1), // mt discovery 1813 ParallelGCThreads, // degree of mt discovery 1814 true, // Reference discovery is atomic 1815 &_is_alive_closure_stw); // is alive closure 1816 } 1817 1818 CollectorPolicy* G1CollectedHeap::collector_policy() const { 1819 return _collector_policy; 1820 } 1821 1822 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1823 return &_soft_ref_policy; 1824 } 1825 1826 size_t G1CollectedHeap::capacity() const { 1827 return _hrm.length() * HeapRegion::GrainBytes; 1828 } 1829 1830 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1831 return _hrm.total_free_bytes(); 1832 } 1833 1834 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) { 1835 _hot_card_cache->drain(cl, worker_i); 1836 } 1837 1838 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) { 1839 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1840 size_t n_completed_buffers = 0; 1841 while (dcqs.apply_closure_during_gc(cl, worker_i)) { 1842 n_completed_buffers++; 1843 } 1844 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers); 1845 dcqs.clear_n_completed_buffers(); 1846 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 1847 } 1848 1849 // Computes the sum of the storage used by the various regions. 1850 size_t G1CollectedHeap::used() const { 1851 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1852 if (_archive_allocator != NULL) { 1853 result += _archive_allocator->used(); 1854 } 1855 return result; 1856 } 1857 1858 size_t G1CollectedHeap::used_unlocked() const { 1859 return _summary_bytes_used; 1860 } 1861 1862 class SumUsedClosure: public HeapRegionClosure { 1863 size_t _used; 1864 public: 1865 SumUsedClosure() : _used(0) {} 1866 bool do_heap_region(HeapRegion* r) { 1867 _used += r->used(); 1868 return false; 1869 } 1870 size_t result() { return _used; } 1871 }; 1872 1873 size_t G1CollectedHeap::recalculate_used() const { 1874 double recalculate_used_start = os::elapsedTime(); 1875 1876 SumUsedClosure blk; 1877 heap_region_iterate(&blk); 1878 1879 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 1880 return blk.result(); 1881 } 1882 1883 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1884 switch (cause) { 1885 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1886 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1887 case GCCause::_wb_conc_mark: return true; 1888 default : return false; 1889 } 1890 } 1891 1892 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 1893 switch (cause) { 1894 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 1895 case GCCause::_g1_humongous_allocation: return true; 1896 default: return is_user_requested_concurrent_full_gc(cause); 1897 } 1898 } 1899 1900 #ifndef PRODUCT 1901 void G1CollectedHeap::allocate_dummy_regions() { 1902 // Let's fill up most of the region 1903 size_t word_size = HeapRegion::GrainWords - 1024; 1904 // And as a result the region we'll allocate will be humongous. 1905 guarantee(is_humongous(word_size), "sanity"); 1906 1907 // _filler_array_max_size is set to humongous object threshold 1908 // but temporarily change it to use CollectedHeap::fill_with_object(). 1909 SizeTFlagSetting fs(_filler_array_max_size, word_size); 1910 1911 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 1912 // Let's use the existing mechanism for the allocation 1913 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 1914 if (dummy_obj != NULL) { 1915 MemRegion mr(dummy_obj, word_size); 1916 CollectedHeap::fill_with_object(mr); 1917 } else { 1918 // If we can't allocate once, we probably cannot allocate 1919 // again. Let's get out of the loop. 1920 break; 1921 } 1922 } 1923 } 1924 #endif // !PRODUCT 1925 1926 void G1CollectedHeap::increment_old_marking_cycles_started() { 1927 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 1928 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 1929 "Wrong marking cycle count (started: %d, completed: %d)", 1930 _old_marking_cycles_started, _old_marking_cycles_completed); 1931 1932 _old_marking_cycles_started++; 1933 } 1934 1935 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 1936 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 1937 1938 // We assume that if concurrent == true, then the caller is a 1939 // concurrent thread that was joined the Suspendible Thread 1940 // Set. If there's ever a cheap way to check this, we should add an 1941 // assert here. 1942 1943 // Given that this method is called at the end of a Full GC or of a 1944 // concurrent cycle, and those can be nested (i.e., a Full GC can 1945 // interrupt a concurrent cycle), the number of full collections 1946 // completed should be either one (in the case where there was no 1947 // nesting) or two (when a Full GC interrupted a concurrent cycle) 1948 // behind the number of full collections started. 1949 1950 // This is the case for the inner caller, i.e. a Full GC. 1951 assert(concurrent || 1952 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 1953 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 1954 "for inner caller (Full GC): _old_marking_cycles_started = %u " 1955 "is inconsistent with _old_marking_cycles_completed = %u", 1956 _old_marking_cycles_started, _old_marking_cycles_completed); 1957 1958 // This is the case for the outer caller, i.e. the concurrent cycle. 1959 assert(!concurrent || 1960 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 1961 "for outer caller (concurrent cycle): " 1962 "_old_marking_cycles_started = %u " 1963 "is inconsistent with _old_marking_cycles_completed = %u", 1964 _old_marking_cycles_started, _old_marking_cycles_completed); 1965 1966 _old_marking_cycles_completed += 1; 1967 1968 // We need to clear the "in_progress" flag in the CM thread before 1969 // we wake up any waiters (especially when ExplicitInvokesConcurrent 1970 // is set) so that if a waiter requests another System.gc() it doesn't 1971 // incorrectly see that a marking cycle is still in progress. 1972 if (concurrent) { 1973 _cm_thread->set_idle(); 1974 } 1975 1976 // This notify_all() will ensure that a thread that called 1977 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 1978 // and it's waiting for a full GC to finish will be woken up. It is 1979 // waiting in VM_G1CollectForAllocation::doit_epilogue(). 1980 FullGCCount_lock->notify_all(); 1981 } 1982 1983 void G1CollectedHeap::collect(GCCause::Cause cause) { 1984 assert_heap_not_locked(); 1985 1986 uint gc_count_before; 1987 uint old_marking_count_before; 1988 uint full_gc_count_before; 1989 bool retry_gc; 1990 1991 do { 1992 retry_gc = false; 1993 1994 { 1995 MutexLocker ml(Heap_lock); 1996 1997 // Read the GC count while holding the Heap_lock 1998 gc_count_before = total_collections(); 1999 full_gc_count_before = total_full_collections(); 2000 old_marking_count_before = _old_marking_cycles_started; 2001 } 2002 2003 if (should_do_concurrent_full_gc(cause)) { 2004 // Schedule an initial-mark evacuation pause that will start a 2005 // concurrent cycle. We're setting word_size to 0 which means that 2006 // we are not requesting a post-GC allocation. 2007 VM_G1CollectForAllocation op(0, /* word_size */ 2008 gc_count_before, 2009 cause, 2010 true, /* should_initiate_conc_mark */ 2011 g1_policy()->max_pause_time_ms()); 2012 VMThread::execute(&op); 2013 if (!op.pause_succeeded()) { 2014 if (old_marking_count_before == _old_marking_cycles_started) { 2015 retry_gc = op.should_retry_gc(); 2016 } else { 2017 // A Full GC happened while we were trying to schedule the 2018 // initial-mark GC. No point in starting a new cycle given 2019 // that the whole heap was collected anyway. 2020 } 2021 2022 if (retry_gc) { 2023 if (GCLocker::is_active_and_needs_gc()) { 2024 GCLocker::stall_until_clear(); 2025 } 2026 } 2027 } 2028 } else { 2029 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2030 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2031 2032 // Schedule a standard evacuation pause. We're setting word_size 2033 // to 0 which means that we are not requesting a post-GC allocation. 2034 VM_G1CollectForAllocation op(0, /* word_size */ 2035 gc_count_before, 2036 cause, 2037 false, /* should_initiate_conc_mark */ 2038 g1_policy()->max_pause_time_ms()); 2039 VMThread::execute(&op); 2040 } else { 2041 // Schedule a Full GC. 2042 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2043 VMThread::execute(&op); 2044 } 2045 } 2046 } while (retry_gc); 2047 } 2048 2049 bool G1CollectedHeap::is_in(const void* p) const { 2050 if (_hrm.reserved().contains(p)) { 2051 // Given that we know that p is in the reserved space, 2052 // heap_region_containing() should successfully 2053 // return the containing region. 2054 HeapRegion* hr = heap_region_containing(p); 2055 return hr->is_in(p); 2056 } else { 2057 return false; 2058 } 2059 } 2060 2061 #ifdef ASSERT 2062 bool G1CollectedHeap::is_in_exact(const void* p) const { 2063 bool contains = reserved_region().contains(p); 2064 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2065 if (contains && available) { 2066 return true; 2067 } else { 2068 return false; 2069 } 2070 } 2071 #endif 2072 2073 // Iteration functions. 2074 2075 // Iterates an ObjectClosure over all objects within a HeapRegion. 2076 2077 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2078 ObjectClosure* _cl; 2079 public: 2080 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2081 bool do_heap_region(HeapRegion* r) { 2082 if (!r->is_continues_humongous()) { 2083 r->object_iterate(_cl); 2084 } 2085 return false; 2086 } 2087 }; 2088 2089 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2090 IterateObjectClosureRegionClosure blk(cl); 2091 heap_region_iterate(&blk); 2092 } 2093 2094 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2095 _hrm.iterate(cl); 2096 } 2097 2098 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2099 HeapRegionClaimer *hrclaimer, 2100 uint worker_id) const { 2101 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2102 } 2103 2104 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2105 HeapRegionClaimer *hrclaimer) const { 2106 _hrm.par_iterate(cl, hrclaimer, 0); 2107 } 2108 2109 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2110 _collection_set.iterate(cl); 2111 } 2112 2113 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) { 2114 _collection_set.iterate_from(cl, worker_id, workers()->active_workers()); 2115 } 2116 2117 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2118 HeapRegion* hr = heap_region_containing(addr); 2119 return hr->block_start(addr); 2120 } 2121 2122 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2123 HeapRegion* hr = heap_region_containing(addr); 2124 return hr->block_size(addr); 2125 } 2126 2127 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2128 HeapRegion* hr = heap_region_containing(addr); 2129 return hr->block_is_obj(addr); 2130 } 2131 2132 bool G1CollectedHeap::supports_tlab_allocation() const { 2133 return true; 2134 } 2135 2136 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2137 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2138 } 2139 2140 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2141 return _eden.length() * HeapRegion::GrainBytes; 2142 } 2143 2144 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2145 // must be equal to the humongous object limit. 2146 size_t G1CollectedHeap::max_tlab_size() const { 2147 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2148 } 2149 2150 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2151 return _allocator->unsafe_max_tlab_alloc(); 2152 } 2153 2154 size_t G1CollectedHeap::max_capacity() const { 2155 return _hrm.reserved().byte_size(); 2156 } 2157 2158 jlong G1CollectedHeap::millis_since_last_gc() { 2159 // See the notes in GenCollectedHeap::millis_since_last_gc() 2160 // for more information about the implementation. 2161 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2162 _g1_policy->collection_pause_end_millis(); 2163 if (ret_val < 0) { 2164 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2165 ". returning zero instead.", ret_val); 2166 return 0; 2167 } 2168 return ret_val; 2169 } 2170 2171 void G1CollectedHeap::deduplicate_string(oop str) { 2172 assert(java_lang_String::is_instance(str), "invariant"); 2173 2174 if (G1StringDedup::is_enabled()) { 2175 G1StringDedup::deduplicate(str); 2176 } 2177 } 2178 2179 void G1CollectedHeap::prepare_for_verify() { 2180 _verifier->prepare_for_verify(); 2181 } 2182 2183 void G1CollectedHeap::verify(VerifyOption vo) { 2184 _verifier->verify(vo); 2185 } 2186 2187 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2188 return true; 2189 } 2190 2191 const char* const* G1CollectedHeap::concurrent_phases() const { 2192 return _cm_thread->concurrent_phases(); 2193 } 2194 2195 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2196 return _cm_thread->request_concurrent_phase(phase); 2197 } 2198 2199 class PrintRegionClosure: public HeapRegionClosure { 2200 outputStream* _st; 2201 public: 2202 PrintRegionClosure(outputStream* st) : _st(st) {} 2203 bool do_heap_region(HeapRegion* r) { 2204 r->print_on(_st); 2205 return false; 2206 } 2207 }; 2208 2209 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2210 const HeapRegion* hr, 2211 const VerifyOption vo) const { 2212 switch (vo) { 2213 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2214 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2215 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2216 default: ShouldNotReachHere(); 2217 } 2218 return false; // keep some compilers happy 2219 } 2220 2221 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2222 const VerifyOption vo) const { 2223 switch (vo) { 2224 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2225 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2226 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2227 default: ShouldNotReachHere(); 2228 } 2229 return false; // keep some compilers happy 2230 } 2231 2232 void G1CollectedHeap::print_heap_regions() const { 2233 LogTarget(Trace, gc, heap, region) lt; 2234 if (lt.is_enabled()) { 2235 LogStream ls(lt); 2236 print_regions_on(&ls); 2237 } 2238 } 2239 2240 void G1CollectedHeap::print_on(outputStream* st) const { 2241 st->print(" %-20s", "garbage-first heap"); 2242 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2243 capacity()/K, used_unlocked()/K); 2244 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2245 p2i(_hrm.reserved().start()), 2246 p2i(_hrm.reserved().end())); 2247 st->cr(); 2248 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2249 uint young_regions = young_regions_count(); 2250 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2251 (size_t) young_regions * HeapRegion::GrainBytes / K); 2252 uint survivor_regions = survivor_regions_count(); 2253 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2254 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2255 st->cr(); 2256 MetaspaceUtils::print_on(st); 2257 } 2258 2259 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2260 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2261 "HS=humongous(starts), HC=humongous(continues), " 2262 "CS=collection set, F=free, A=archive, " 2263 "TAMS=top-at-mark-start (previous, next)"); 2264 PrintRegionClosure blk(st); 2265 heap_region_iterate(&blk); 2266 } 2267 2268 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2269 print_on(st); 2270 2271 // Print the per-region information. 2272 print_regions_on(st); 2273 } 2274 2275 void G1CollectedHeap::print_on_error(outputStream* st) const { 2276 this->CollectedHeap::print_on_error(st); 2277 2278 if (_cm != NULL) { 2279 st->cr(); 2280 _cm->print_on_error(st); 2281 } 2282 } 2283 2284 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2285 workers()->print_worker_threads_on(st); 2286 _cm_thread->print_on(st); 2287 st->cr(); 2288 _cm->print_worker_threads_on(st); 2289 _cr->print_threads_on(st); 2290 _young_gen_sampling_thread->print_on(st); 2291 if (G1StringDedup::is_enabled()) { 2292 G1StringDedup::print_worker_threads_on(st); 2293 } 2294 } 2295 2296 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2297 workers()->threads_do(tc); 2298 tc->do_thread(_cm_thread); 2299 _cm->threads_do(tc); 2300 _cr->threads_do(tc); 2301 tc->do_thread(_young_gen_sampling_thread); 2302 if (G1StringDedup::is_enabled()) { 2303 G1StringDedup::threads_do(tc); 2304 } 2305 } 2306 2307 void G1CollectedHeap::print_tracing_info() const { 2308 g1_rem_set()->print_summary_info(); 2309 concurrent_mark()->print_summary_info(); 2310 } 2311 2312 #ifndef PRODUCT 2313 // Helpful for debugging RSet issues. 2314 2315 class PrintRSetsClosure : public HeapRegionClosure { 2316 private: 2317 const char* _msg; 2318 size_t _occupied_sum; 2319 2320 public: 2321 bool do_heap_region(HeapRegion* r) { 2322 HeapRegionRemSet* hrrs = r->rem_set(); 2323 size_t occupied = hrrs->occupied(); 2324 _occupied_sum += occupied; 2325 2326 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2327 if (occupied == 0) { 2328 tty->print_cr(" RSet is empty"); 2329 } else { 2330 hrrs->print(); 2331 } 2332 tty->print_cr("----------"); 2333 return false; 2334 } 2335 2336 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2337 tty->cr(); 2338 tty->print_cr("========================================"); 2339 tty->print_cr("%s", msg); 2340 tty->cr(); 2341 } 2342 2343 ~PrintRSetsClosure() { 2344 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2345 tty->print_cr("========================================"); 2346 tty->cr(); 2347 } 2348 }; 2349 2350 void G1CollectedHeap::print_cset_rsets() { 2351 PrintRSetsClosure cl("Printing CSet RSets"); 2352 collection_set_iterate(&cl); 2353 } 2354 2355 void G1CollectedHeap::print_all_rsets() { 2356 PrintRSetsClosure cl("Printing All RSets");; 2357 heap_region_iterate(&cl); 2358 } 2359 #endif // PRODUCT 2360 2361 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2362 2363 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes; 2364 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes; 2365 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2366 2367 size_t eden_capacity_bytes = 2368 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2369 2370 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2371 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2372 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2373 } 2374 2375 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2376 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2377 stats->unused(), stats->used(), stats->region_end_waste(), 2378 stats->regions_filled(), stats->direct_allocated(), 2379 stats->failure_used(), stats->failure_waste()); 2380 } 2381 2382 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2383 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2384 gc_tracer->report_gc_heap_summary(when, heap_summary); 2385 2386 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2387 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2388 } 2389 2390 G1CollectedHeap* G1CollectedHeap::heap() { 2391 CollectedHeap* heap = Universe::heap(); 2392 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2393 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2394 return (G1CollectedHeap*)heap; 2395 } 2396 2397 void G1CollectedHeap::gc_prologue(bool full) { 2398 // always_do_update_barrier = false; 2399 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2400 2401 // This summary needs to be printed before incrementing total collections. 2402 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2403 2404 // Update common counters. 2405 increment_total_collections(full /* full gc */); 2406 if (full) { 2407 increment_old_marking_cycles_started(); 2408 } 2409 2410 // Fill TLAB's and such 2411 double start = os::elapsedTime(); 2412 accumulate_statistics_all_tlabs(); 2413 ensure_parsability(true); 2414 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2415 } 2416 2417 void G1CollectedHeap::gc_epilogue(bool full) { 2418 // Update common counters. 2419 if (full) { 2420 // Update the number of full collections that have been completed. 2421 increment_old_marking_cycles_completed(false /* concurrent */); 2422 } 2423 2424 // We are at the end of the GC. Total collections has already been increased. 2425 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2426 2427 // FIXME: what is this about? 2428 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2429 // is set. 2430 #if COMPILER2_OR_JVMCI 2431 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2432 #endif 2433 // always_do_update_barrier = true; 2434 2435 double start = os::elapsedTime(); 2436 resize_all_tlabs(); 2437 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2438 2439 MemoryService::track_memory_usage(); 2440 // We have just completed a GC. Update the soft reference 2441 // policy with the new heap occupancy 2442 Universe::update_heap_info_at_gc(); 2443 } 2444 2445 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2446 uint gc_count_before, 2447 bool* succeeded, 2448 GCCause::Cause gc_cause) { 2449 assert_heap_not_locked_and_not_at_safepoint(); 2450 VM_G1CollectForAllocation op(word_size, 2451 gc_count_before, 2452 gc_cause, 2453 false, /* should_initiate_conc_mark */ 2454 g1_policy()->max_pause_time_ms()); 2455 VMThread::execute(&op); 2456 2457 HeapWord* result = op.result(); 2458 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 2459 assert(result == NULL || ret_succeeded, 2460 "the result should be NULL if the VM did not succeed"); 2461 *succeeded = ret_succeeded; 2462 2463 assert_heap_not_locked(); 2464 return result; 2465 } 2466 2467 void G1CollectedHeap::do_concurrent_mark() { 2468 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 2469 if (!_cm_thread->in_progress()) { 2470 _cm_thread->set_started(); 2471 CGC_lock->notify(); 2472 } 2473 } 2474 2475 size_t G1CollectedHeap::pending_card_num() { 2476 size_t extra_cards = 0; 2477 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) { 2478 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr); 2479 extra_cards += dcq.size(); 2480 } 2481 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 2482 size_t buffer_size = dcqs.buffer_size(); 2483 size_t buffer_num = dcqs.completed_buffers_num(); 2484 2485 return buffer_size * buffer_num + extra_cards; 2486 } 2487 2488 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2489 // We don't nominate objects with many remembered set entries, on 2490 // the assumption that such objects are likely still live. 2491 HeapRegionRemSet* rem_set = r->rem_set(); 2492 2493 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2494 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2495 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2496 } 2497 2498 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 2499 private: 2500 size_t _total_humongous; 2501 size_t _candidate_humongous; 2502 2503 DirtyCardQueue _dcq; 2504 2505 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const { 2506 assert(region->is_starts_humongous(), "Must start a humongous object"); 2507 2508 oop obj = oop(region->bottom()); 2509 2510 // Dead objects cannot be eager reclaim candidates. Due to class 2511 // unloading it is unsafe to query their classes so we return early. 2512 if (g1h->is_obj_dead(obj, region)) { 2513 return false; 2514 } 2515 2516 // If we do not have a complete remembered set for the region, then we can 2517 // not be sure that we have all references to it. 2518 if (!region->rem_set()->is_complete()) { 2519 return false; 2520 } 2521 // Candidate selection must satisfy the following constraints 2522 // while concurrent marking is in progress: 2523 // 2524 // * In order to maintain SATB invariants, an object must not be 2525 // reclaimed if it was allocated before the start of marking and 2526 // has not had its references scanned. Such an object must have 2527 // its references (including type metadata) scanned to ensure no 2528 // live objects are missed by the marking process. Objects 2529 // allocated after the start of concurrent marking don't need to 2530 // be scanned. 2531 // 2532 // * An object must not be reclaimed if it is on the concurrent 2533 // mark stack. Objects allocated after the start of concurrent 2534 // marking are never pushed on the mark stack. 2535 // 2536 // Nominating only objects allocated after the start of concurrent 2537 // marking is sufficient to meet both constraints. This may miss 2538 // some objects that satisfy the constraints, but the marking data 2539 // structures don't support efficiently performing the needed 2540 // additional tests or scrubbing of the mark stack. 2541 // 2542 // However, we presently only nominate is_typeArray() objects. 2543 // A humongous object containing references induces remembered 2544 // set entries on other regions. In order to reclaim such an 2545 // object, those remembered sets would need to be cleaned up. 2546 // 2547 // We also treat is_typeArray() objects specially, allowing them 2548 // to be reclaimed even if allocated before the start of 2549 // concurrent mark. For this we rely on mark stack insertion to 2550 // exclude is_typeArray() objects, preventing reclaiming an object 2551 // that is in the mark stack. We also rely on the metadata for 2552 // such objects to be built-in and so ensured to be kept live. 2553 // Frequent allocation and drop of large binary blobs is an 2554 // important use case for eager reclaim, and this special handling 2555 // may reduce needed headroom. 2556 2557 return obj->is_typeArray() && 2558 g1h->is_potential_eager_reclaim_candidate(region); 2559 } 2560 2561 public: 2562 RegisterHumongousWithInCSetFastTestClosure() 2563 : _total_humongous(0), 2564 _candidate_humongous(0), 2565 _dcq(&G1BarrierSet::dirty_card_queue_set()) { 2566 } 2567 2568 virtual bool do_heap_region(HeapRegion* r) { 2569 if (!r->is_starts_humongous()) { 2570 return false; 2571 } 2572 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2573 2574 bool is_candidate = humongous_region_is_candidate(g1h, r); 2575 uint rindex = r->hrm_index(); 2576 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2577 if (is_candidate) { 2578 _candidate_humongous++; 2579 g1h->register_humongous_region_with_cset(rindex); 2580 // Is_candidate already filters out humongous object with large remembered sets. 2581 // If we have a humongous object with a few remembered sets, we simply flush these 2582 // remembered set entries into the DCQS. That will result in automatic 2583 // re-evaluation of their remembered set entries during the following evacuation 2584 // phase. 2585 if (!r->rem_set()->is_empty()) { 2586 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 2587 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 2588 G1CardTable* ct = g1h->card_table(); 2589 HeapRegionRemSetIterator hrrs(r->rem_set()); 2590 size_t card_index; 2591 while (hrrs.has_next(card_index)) { 2592 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index); 2593 // The remembered set might contain references to already freed 2594 // regions. Filter out such entries to avoid failing card table 2595 // verification. 2596 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) { 2597 if (*card_ptr != G1CardTable::dirty_card_val()) { 2598 *card_ptr = G1CardTable::dirty_card_val(); 2599 _dcq.enqueue(card_ptr); 2600 } 2601 } 2602 } 2603 assert(hrrs.n_yielded() == r->rem_set()->occupied(), 2604 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", 2605 hrrs.n_yielded(), r->rem_set()->occupied()); 2606 // We should only clear the card based remembered set here as we will not 2607 // implicitly rebuild anything else during eager reclaim. Note that at the moment 2608 // (and probably never) we do not enter this path if there are other kind of 2609 // remembered sets for this region. 2610 r->rem_set()->clear_locked(true /* only_cardset */); 2611 // Clear_locked() above sets the state to Empty. However we want to continue 2612 // collecting remembered set entries for humongous regions that were not 2613 // reclaimed. 2614 r->rem_set()->set_state_complete(); 2615 } 2616 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 2617 } 2618 _total_humongous++; 2619 2620 return false; 2621 } 2622 2623 size_t total_humongous() const { return _total_humongous; } 2624 size_t candidate_humongous() const { return _candidate_humongous; } 2625 2626 void flush_rem_set_entries() { _dcq.flush(); } 2627 }; 2628 2629 void G1CollectedHeap::register_humongous_regions_with_cset() { 2630 if (!G1EagerReclaimHumongousObjects) { 2631 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 2632 return; 2633 } 2634 double time = os::elapsed_counter(); 2635 2636 // Collect reclaim candidate information and register candidates with cset. 2637 RegisterHumongousWithInCSetFastTestClosure cl; 2638 heap_region_iterate(&cl); 2639 2640 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 2641 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 2642 cl.total_humongous(), 2643 cl.candidate_humongous()); 2644 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2645 2646 // Finally flush all remembered set entries to re-check into the global DCQS. 2647 cl.flush_rem_set_entries(); 2648 } 2649 2650 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2651 public: 2652 bool do_heap_region(HeapRegion* hr) { 2653 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2654 hr->verify_rem_set(); 2655 } 2656 return false; 2657 } 2658 }; 2659 2660 uint G1CollectedHeap::num_task_queues() const { 2661 return _task_queues->size(); 2662 } 2663 2664 #if TASKQUEUE_STATS 2665 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2666 st->print_raw_cr("GC Task Stats"); 2667 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2668 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2669 } 2670 2671 void G1CollectedHeap::print_taskqueue_stats() const { 2672 if (!log_is_enabled(Trace, gc, task, stats)) { 2673 return; 2674 } 2675 Log(gc, task, stats) log; 2676 ResourceMark rm; 2677 LogStream ls(log.trace()); 2678 outputStream* st = &ls; 2679 2680 print_taskqueue_stats_hdr(st); 2681 2682 TaskQueueStats totals; 2683 const uint n = num_task_queues(); 2684 for (uint i = 0; i < n; ++i) { 2685 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2686 totals += task_queue(i)->stats; 2687 } 2688 st->print_raw("tot "); totals.print(st); st->cr(); 2689 2690 DEBUG_ONLY(totals.verify()); 2691 } 2692 2693 void G1CollectedHeap::reset_taskqueue_stats() { 2694 const uint n = num_task_queues(); 2695 for (uint i = 0; i < n; ++i) { 2696 task_queue(i)->stats.reset(); 2697 } 2698 } 2699 #endif // TASKQUEUE_STATS 2700 2701 void G1CollectedHeap::wait_for_root_region_scanning() { 2702 double scan_wait_start = os::elapsedTime(); 2703 // We have to wait until the CM threads finish scanning the 2704 // root regions as it's the only way to ensure that all the 2705 // objects on them have been correctly scanned before we start 2706 // moving them during the GC. 2707 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2708 double wait_time_ms = 0.0; 2709 if (waited) { 2710 double scan_wait_end = os::elapsedTime(); 2711 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2712 } 2713 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2714 } 2715 2716 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2717 private: 2718 G1HRPrinter* _hr_printer; 2719 public: 2720 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2721 2722 virtual bool do_heap_region(HeapRegion* r) { 2723 _hr_printer->cset(r); 2724 return false; 2725 } 2726 }; 2727 2728 void G1CollectedHeap::start_new_collection_set() { 2729 collection_set()->start_incremental_building(); 2730 2731 clear_cset_fast_test(); 2732 2733 guarantee(_eden.length() == 0, "eden should have been cleared"); 2734 g1_policy()->transfer_survivors_to_cset(survivor()); 2735 } 2736 2737 bool 2738 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2739 assert_at_safepoint_on_vm_thread(); 2740 guarantee(!is_gc_active(), "collection is not reentrant"); 2741 2742 if (GCLocker::check_active_before_gc()) { 2743 return false; 2744 } 2745 2746 _gc_timer_stw->register_gc_start(); 2747 2748 GCIdMark gc_id_mark; 2749 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2750 2751 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2752 ResourceMark rm; 2753 2754 g1_policy()->note_gc_start(); 2755 2756 wait_for_root_region_scanning(); 2757 2758 print_heap_before_gc(); 2759 print_heap_regions(); 2760 trace_heap_before_gc(_gc_tracer_stw); 2761 2762 _verifier->verify_region_sets_optional(); 2763 _verifier->verify_dirty_young_regions(); 2764 2765 // We should not be doing initial mark unless the conc mark thread is running 2766 if (!_cm_thread->should_terminate()) { 2767 // This call will decide whether this pause is an initial-mark 2768 // pause. If it is, in_initial_mark_gc() will return true 2769 // for the duration of this pause. 2770 g1_policy()->decide_on_conc_mark_initiation(); 2771 } 2772 2773 // We do not allow initial-mark to be piggy-backed on a mixed GC. 2774 assert(!collector_state()->in_initial_mark_gc() || 2775 collector_state()->in_young_only_phase(), "sanity"); 2776 2777 // We also do not allow mixed GCs during marking. 2778 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 2779 2780 // Record whether this pause is an initial mark. When the current 2781 // thread has completed its logging output and it's safe to signal 2782 // the CM thread, the flag's value in the policy has been reset. 2783 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 2784 2785 // Inner scope for scope based logging, timers, and stats collection 2786 { 2787 EvacuationInfo evacuation_info; 2788 2789 if (collector_state()->in_initial_mark_gc()) { 2790 // We are about to start a marking cycle, so we increment the 2791 // full collection counter. 2792 increment_old_marking_cycles_started(); 2793 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2794 } 2795 2796 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 2797 2798 GCTraceCPUTime tcpu; 2799 2800 G1HeapVerifier::G1VerifyType verify_type; 2801 FormatBuffer<> gc_string("Pause "); 2802 if (collector_state()->in_initial_mark_gc()) { 2803 gc_string.append("Initial Mark"); 2804 verify_type = G1HeapVerifier::G1VerifyInitialMark; 2805 } else if (collector_state()->in_young_only_phase()) { 2806 gc_string.append("Young"); 2807 verify_type = G1HeapVerifier::G1VerifyYoungOnly; 2808 } else { 2809 gc_string.append("Mixed"); 2810 verify_type = G1HeapVerifier::G1VerifyMixed; 2811 } 2812 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true); 2813 2814 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 2815 workers()->active_workers(), 2816 Threads::number_of_non_daemon_threads()); 2817 active_workers = workers()->update_active_workers(active_workers); 2818 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 2819 2820 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 2821 TraceMemoryManagerStats tms(&_memory_manager, gc_cause()); 2822 2823 G1HeapTransition heap_transition(this); 2824 size_t heap_used_bytes_before_gc = used(); 2825 2826 // Don't dynamically change the number of GC threads this early. A value of 2827 // 0 is used to indicate serial work. When parallel work is done, 2828 // it will be set. 2829 2830 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 2831 IsGCActiveMark x; 2832 2833 gc_prologue(false); 2834 2835 if (VerifyRememberedSets) { 2836 log_info(gc, verify)("[Verifying RemSets before GC]"); 2837 VerifyRegionRemSetClosure v_cl; 2838 heap_region_iterate(&v_cl); 2839 } 2840 2841 _verifier->verify_before_gc(verify_type); 2842 2843 _verifier->check_bitmaps("GC Start"); 2844 2845 #if COMPILER2_OR_JVMCI 2846 DerivedPointerTable::clear(); 2847 #endif 2848 2849 // Please see comment in g1CollectedHeap.hpp and 2850 // G1CollectedHeap::ref_processing_init() to see how 2851 // reference processing currently works in G1. 2852 2853 // Enable discovery in the STW reference processor 2854 _ref_processor_stw->enable_discovery(); 2855 2856 { 2857 // We want to temporarily turn off discovery by the 2858 // CM ref processor, if necessary, and turn it back on 2859 // on again later if we do. Using a scoped 2860 // NoRefDiscovery object will do this. 2861 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 2862 2863 // Forget the current alloc region (we might even choose it to be part 2864 // of the collection set!). 2865 _allocator->release_mutator_alloc_region(); 2866 2867 // This timing is only used by the ergonomics to handle our pause target. 2868 // It is unclear why this should not include the full pause. We will 2869 // investigate this in CR 7178365. 2870 // 2871 // Preserving the old comment here if that helps the investigation: 2872 // 2873 // The elapsed time induced by the start time below deliberately elides 2874 // the possible verification above. 2875 double sample_start_time_sec = os::elapsedTime(); 2876 2877 g1_policy()->record_collection_pause_start(sample_start_time_sec); 2878 2879 if (collector_state()->in_initial_mark_gc()) { 2880 concurrent_mark()->pre_initial_mark(); 2881 } 2882 2883 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor); 2884 2885 evacuation_info.set_collectionset_regions(collection_set()->region_length()); 2886 2887 // Make sure the remembered sets are up to date. This needs to be 2888 // done before register_humongous_regions_with_cset(), because the 2889 // remembered sets are used there to choose eager reclaim candidates. 2890 // If the remembered sets are not up to date we might miss some 2891 // entries that need to be handled. 2892 g1_rem_set()->cleanupHRRS(); 2893 2894 register_humongous_regions_with_cset(); 2895 2896 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table."); 2897 2898 // We call this after finalize_cset() to 2899 // ensure that the CSet has been finalized. 2900 _cm->verify_no_cset_oops(); 2901 2902 if (_hr_printer.is_active()) { 2903 G1PrintCollectionSetClosure cl(&_hr_printer); 2904 _collection_set.iterate(&cl); 2905 } 2906 2907 // Initialize the GC alloc regions. 2908 _allocator->init_gc_alloc_regions(evacuation_info); 2909 2910 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length()); 2911 pre_evacuate_collection_set(); 2912 2913 // Actually do the work... 2914 evacuate_collection_set(&per_thread_states); 2915 2916 post_evacuate_collection_set(evacuation_info, &per_thread_states); 2917 2918 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 2919 free_collection_set(&_collection_set, evacuation_info, surviving_young_words); 2920 2921 eagerly_reclaim_humongous_regions(); 2922 2923 record_obj_copy_mem_stats(); 2924 _survivor_evac_stats.adjust_desired_plab_sz(); 2925 _old_evac_stats.adjust_desired_plab_sz(); 2926 2927 double start = os::elapsedTime(); 2928 start_new_collection_set(); 2929 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 2930 2931 if (evacuation_failed()) { 2932 set_used(recalculate_used()); 2933 if (_archive_allocator != NULL) { 2934 _archive_allocator->clear_used(); 2935 } 2936 for (uint i = 0; i < ParallelGCThreads; i++) { 2937 if (_evacuation_failed_info_array[i].has_failed()) { 2938 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 2939 } 2940 } 2941 } else { 2942 // The "used" of the the collection set have already been subtracted 2943 // when they were freed. Add in the bytes evacuated. 2944 increase_used(g1_policy()->bytes_copied_during_gc()); 2945 } 2946 2947 if (collector_state()->in_initial_mark_gc()) { 2948 // We have to do this before we notify the CM threads that 2949 // they can start working to make sure that all the 2950 // appropriate initialization is done on the CM object. 2951 concurrent_mark()->post_initial_mark(); 2952 // Note that we don't actually trigger the CM thread at 2953 // this point. We do that later when we're sure that 2954 // the current thread has completed its logging output. 2955 } 2956 2957 allocate_dummy_regions(); 2958 2959 _allocator->init_mutator_alloc_region(); 2960 2961 { 2962 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 2963 if (expand_bytes > 0) { 2964 size_t bytes_before = capacity(); 2965 // No need for an ergo logging here, 2966 // expansion_amount() does this when it returns a value > 0. 2967 double expand_ms; 2968 if (!expand(expand_bytes, _workers, &expand_ms)) { 2969 // We failed to expand the heap. Cannot do anything about it. 2970 } 2971 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 2972 } 2973 } 2974 2975 // We redo the verification but now wrt to the new CSet which 2976 // has just got initialized after the previous CSet was freed. 2977 _cm->verify_no_cset_oops(); 2978 2979 // This timing is only used by the ergonomics to handle our pause target. 2980 // It is unclear why this should not include the full pause. We will 2981 // investigate this in CR 7178365. 2982 double sample_end_time_sec = os::elapsedTime(); 2983 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 2984 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards); 2985 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc); 2986 2987 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 2988 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 2989 2990 if (VerifyRememberedSets) { 2991 log_info(gc, verify)("[Verifying RemSets after GC]"); 2992 VerifyRegionRemSetClosure v_cl; 2993 heap_region_iterate(&v_cl); 2994 } 2995 2996 _verifier->verify_after_gc(verify_type); 2997 _verifier->check_bitmaps("GC End"); 2998 2999 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 3000 _ref_processor_stw->verify_no_references_recorded(); 3001 3002 // CM reference discovery will be re-enabled if necessary. 3003 } 3004 3005 #ifdef TRACESPINNING 3006 ParallelTaskTerminator::print_termination_counts(); 3007 #endif 3008 3009 gc_epilogue(false); 3010 } 3011 3012 // Print the remainder of the GC log output. 3013 if (evacuation_failed()) { 3014 log_info(gc)("To-space exhausted"); 3015 } 3016 3017 g1_policy()->print_phases(); 3018 heap_transition.print(); 3019 3020 // It is not yet to safe to tell the concurrent mark to 3021 // start as we have some optional output below. We don't want the 3022 // output from the concurrent mark thread interfering with this 3023 // logging output either. 3024 3025 _hrm.verify_optional(); 3026 _verifier->verify_region_sets_optional(); 3027 3028 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3029 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3030 3031 print_heap_after_gc(); 3032 print_heap_regions(); 3033 trace_heap_after_gc(_gc_tracer_stw); 3034 3035 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3036 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3037 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3038 // before any GC notifications are raised. 3039 g1mm()->update_sizes(); 3040 3041 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3042 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 3043 _gc_timer_stw->register_gc_end(); 3044 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3045 } 3046 // It should now be safe to tell the concurrent mark thread to start 3047 // without its logging output interfering with the logging output 3048 // that came from the pause. 3049 3050 if (should_start_conc_mark) { 3051 // CAUTION: after the doConcurrentMark() call below, 3052 // the concurrent marking thread(s) could be running 3053 // concurrently with us. Make sure that anything after 3054 // this point does not assume that we are the only GC thread 3055 // running. Note: of course, the actual marking work will 3056 // not start until the safepoint itself is released in 3057 // SuspendibleThreadSet::desynchronize(). 3058 do_concurrent_mark(); 3059 } 3060 3061 return true; 3062 } 3063 3064 void G1CollectedHeap::remove_self_forwarding_pointers() { 3065 G1ParRemoveSelfForwardPtrsTask rsfp_task; 3066 workers()->run_task(&rsfp_task); 3067 } 3068 3069 void G1CollectedHeap::restore_after_evac_failure() { 3070 double remove_self_forwards_start = os::elapsedTime(); 3071 3072 remove_self_forwarding_pointers(); 3073 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3074 _preserved_marks_set.restore(&task_executor); 3075 3076 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3077 } 3078 3079 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 3080 if (!_evacuation_failed) { 3081 _evacuation_failed = true; 3082 } 3083 3084 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3085 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3086 } 3087 3088 bool G1ParEvacuateFollowersClosure::offer_termination() { 3089 G1ParScanThreadState* const pss = par_scan_state(); 3090 start_term_time(); 3091 const bool res = terminator()->offer_termination(); 3092 end_term_time(); 3093 return res; 3094 } 3095 3096 void G1ParEvacuateFollowersClosure::do_void() { 3097 G1ParScanThreadState* const pss = par_scan_state(); 3098 pss->trim_queue(); 3099 do { 3100 pss->steal_and_trim_queue(queues()); 3101 } while (!offer_termination()); 3102 } 3103 3104 class G1ParTask : public AbstractGangTask { 3105 protected: 3106 G1CollectedHeap* _g1h; 3107 G1ParScanThreadStateSet* _pss; 3108 RefToScanQueueSet* _queues; 3109 G1RootProcessor* _root_processor; 3110 ParallelTaskTerminator _terminator; 3111 uint _n_workers; 3112 3113 public: 3114 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 3115 : AbstractGangTask("G1 collection"), 3116 _g1h(g1h), 3117 _pss(per_thread_states), 3118 _queues(task_queues), 3119 _root_processor(root_processor), 3120 _terminator(n_workers, _queues), 3121 _n_workers(n_workers) 3122 {} 3123 3124 void work(uint worker_id) { 3125 if (worker_id >= _n_workers) return; // no work needed this round 3126 3127 double start_sec = os::elapsedTime(); 3128 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 3129 3130 { 3131 ResourceMark rm; 3132 HandleMark hm; 3133 3134 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 3135 3136 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3137 pss->set_ref_discoverer(rp); 3138 3139 double start_strong_roots_sec = os::elapsedTime(); 3140 3141 _root_processor->evacuate_roots(pss, worker_id); 3142 3143 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid 3144 // treating the nmethods visited to act as roots for concurrent marking. 3145 // We only want to make sure that the oops in the nmethods are adjusted with regard to the 3146 // objects copied by the current evacuation. 3147 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id); 3148 3149 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 3150 3151 double term_sec = 0.0; 3152 size_t evac_term_attempts = 0; 3153 { 3154 double start = os::elapsedTime(); 3155 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator); 3156 evac.do_void(); 3157 3158 evac_term_attempts = evac.term_attempts(); 3159 term_sec = evac.term_time(); 3160 double elapsed_sec = os::elapsedTime() - start; 3161 3162 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times(); 3163 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 3164 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 3165 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 3166 } 3167 3168 assert(pss->queue_is_empty(), "should be empty"); 3169 3170 if (log_is_enabled(Debug, gc, task, stats)) { 3171 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3172 size_t lab_waste; 3173 size_t lab_undo_waste; 3174 pss->waste(lab_waste, lab_undo_waste); 3175 _g1h->print_termination_stats(worker_id, 3176 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 3177 strong_roots_sec * 1000.0, /* strong roots time */ 3178 term_sec * 1000.0, /* evac term time */ 3179 evac_term_attempts, /* evac term attempts */ 3180 lab_waste, /* alloc buffer waste */ 3181 lab_undo_waste /* undo waste */ 3182 ); 3183 } 3184 3185 // Close the inner scope so that the ResourceMark and HandleMark 3186 // destructors are executed here and are included as part of the 3187 // "GC Worker Time". 3188 } 3189 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 3190 } 3191 }; 3192 3193 void G1CollectedHeap::print_termination_stats_hdr() { 3194 log_debug(gc, task, stats)("GC Termination Stats"); 3195 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 3196 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo"); 3197 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 3198 } 3199 3200 void G1CollectedHeap::print_termination_stats(uint worker_id, 3201 double elapsed_ms, 3202 double strong_roots_ms, 3203 double term_ms, 3204 size_t term_attempts, 3205 size_t alloc_buffer_waste, 3206 size_t undo_waste) const { 3207 log_debug(gc, task, stats) 3208 ("%3d %9.2f %9.2f %6.2f " 3209 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 3210 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 3211 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 3212 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 3213 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 3214 alloc_buffer_waste * HeapWordSize / K, 3215 undo_waste * HeapWordSize / K); 3216 } 3217 3218 class G1StringAndSymbolCleaningTask : public AbstractGangTask { 3219 private: 3220 BoolObjectClosure* _is_alive; 3221 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure; 3222 OopStorage::ParState<false /* concurrent */, false /* const */> _par_state_string; 3223 3224 int _initial_string_table_size; 3225 int _initial_symbol_table_size; 3226 3227 bool _process_strings; 3228 int _strings_processed; 3229 int _strings_removed; 3230 3231 bool _process_symbols; 3232 int _symbols_processed; 3233 int _symbols_removed; 3234 3235 bool _process_string_dedup; 3236 3237 public: 3238 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) : 3239 AbstractGangTask("String/Symbol Unlinking"), 3240 _is_alive(is_alive), 3241 _dedup_closure(is_alive, NULL, false), 3242 _par_state_string(StringTable::weak_storage()), 3243 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 3244 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0), 3245 _process_string_dedup(process_string_dedup) { 3246 3247 _initial_string_table_size = (int) StringTable::the_table()->table_size(); 3248 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 3249 if (process_symbols) { 3250 SymbolTable::clear_parallel_claimed_index(); 3251 } 3252 } 3253 3254 ~G1StringAndSymbolCleaningTask() { 3255 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 3256 "claim value %d after unlink less than initial symbol table size %d", 3257 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size); 3258 3259 log_info(gc, stringtable)( 3260 "Cleaned string and symbol table, " 3261 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, " 3262 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed", 3263 strings_processed(), strings_removed(), 3264 symbols_processed(), symbols_removed()); 3265 } 3266 3267 void work(uint worker_id) { 3268 int strings_processed = 0; 3269 int strings_removed = 0; 3270 int symbols_processed = 0; 3271 int symbols_removed = 0; 3272 if (_process_strings) { 3273 StringTable::possibly_parallel_unlink(&_par_state_string, _is_alive, &strings_processed, &strings_removed); 3274 Atomic::add(strings_processed, &_strings_processed); 3275 Atomic::add(strings_removed, &_strings_removed); 3276 } 3277 if (_process_symbols) { 3278 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 3279 Atomic::add(symbols_processed, &_symbols_processed); 3280 Atomic::add(symbols_removed, &_symbols_removed); 3281 } 3282 if (_process_string_dedup) { 3283 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id); 3284 } 3285 } 3286 3287 size_t strings_processed() const { return (size_t)_strings_processed; } 3288 size_t strings_removed() const { return (size_t)_strings_removed; } 3289 3290 size_t symbols_processed() const { return (size_t)_symbols_processed; } 3291 size_t symbols_removed() const { return (size_t)_symbols_removed; } 3292 }; 3293 3294 class G1CodeCacheUnloadingTask { 3295 private: 3296 static Monitor* _lock; 3297 3298 BoolObjectClosure* const _is_alive; 3299 const bool _unloading_occurred; 3300 const uint _num_workers; 3301 3302 // Variables used to claim nmethods. 3303 CompiledMethod* _first_nmethod; 3304 CompiledMethod* volatile _claimed_nmethod; 3305 3306 // The list of nmethods that need to be processed by the second pass. 3307 CompiledMethod* volatile _postponed_list; 3308 volatile uint _num_entered_barrier; 3309 3310 public: 3311 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 3312 _is_alive(is_alive), 3313 _unloading_occurred(unloading_occurred), 3314 _num_workers(num_workers), 3315 _first_nmethod(NULL), 3316 _claimed_nmethod(NULL), 3317 _postponed_list(NULL), 3318 _num_entered_barrier(0) 3319 { 3320 CompiledMethod::increase_unloading_clock(); 3321 // Get first alive nmethod 3322 CompiledMethodIterator iter = CompiledMethodIterator(); 3323 if(iter.next_alive()) { 3324 _first_nmethod = iter.method(); 3325 } 3326 _claimed_nmethod = _first_nmethod; 3327 } 3328 3329 ~G1CodeCacheUnloadingTask() { 3330 CodeCache::verify_clean_inline_caches(); 3331 3332 CodeCache::set_needs_cache_clean(false); 3333 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 3334 3335 CodeCache::verify_icholder_relocations(); 3336 } 3337 3338 private: 3339 void add_to_postponed_list(CompiledMethod* nm) { 3340 CompiledMethod* old; 3341 do { 3342 old = _postponed_list; 3343 nm->set_unloading_next(old); 3344 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old); 3345 } 3346 3347 void clean_nmethod(CompiledMethod* nm) { 3348 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 3349 3350 if (postponed) { 3351 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 3352 add_to_postponed_list(nm); 3353 } 3354 3355 // Mark that this nmethod has been cleaned/unloaded. 3356 // After this call, it will be safe to ask if this nmethod was unloaded or not. 3357 nm->set_unloading_clock(CompiledMethod::global_unloading_clock()); 3358 } 3359 3360 void clean_nmethod_postponed(CompiledMethod* nm) { 3361 nm->do_unloading_parallel_postponed(); 3362 } 3363 3364 static const int MaxClaimNmethods = 16; 3365 3366 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) { 3367 CompiledMethod* first; 3368 CompiledMethodIterator last; 3369 3370 do { 3371 *num_claimed_nmethods = 0; 3372 3373 first = _claimed_nmethod; 3374 last = CompiledMethodIterator(first); 3375 3376 if (first != NULL) { 3377 3378 for (int i = 0; i < MaxClaimNmethods; i++) { 3379 if (!last.next_alive()) { 3380 break; 3381 } 3382 claimed_nmethods[i] = last.method(); 3383 (*num_claimed_nmethods)++; 3384 } 3385 } 3386 3387 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first); 3388 } 3389 3390 CompiledMethod* claim_postponed_nmethod() { 3391 CompiledMethod* claim; 3392 CompiledMethod* next; 3393 3394 do { 3395 claim = _postponed_list; 3396 if (claim == NULL) { 3397 return NULL; 3398 } 3399 3400 next = claim->unloading_next(); 3401 3402 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim); 3403 3404 return claim; 3405 } 3406 3407 public: 3408 // Mark that we're done with the first pass of nmethod cleaning. 3409 void barrier_mark(uint worker_id) { 3410 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3411 _num_entered_barrier++; 3412 if (_num_entered_barrier == _num_workers) { 3413 ml.notify_all(); 3414 } 3415 } 3416 3417 // See if we have to wait for the other workers to 3418 // finish their first-pass nmethod cleaning work. 3419 void barrier_wait(uint worker_id) { 3420 if (_num_entered_barrier < _num_workers) { 3421 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3422 while (_num_entered_barrier < _num_workers) { 3423 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 3424 } 3425 } 3426 } 3427 3428 // Cleaning and unloading of nmethods. Some work has to be postponed 3429 // to the second pass, when we know which nmethods survive. 3430 void work_first_pass(uint worker_id) { 3431 // The first nmethods is claimed by the first worker. 3432 if (worker_id == 0 && _first_nmethod != NULL) { 3433 clean_nmethod(_first_nmethod); 3434 _first_nmethod = NULL; 3435 } 3436 3437 int num_claimed_nmethods; 3438 CompiledMethod* claimed_nmethods[MaxClaimNmethods]; 3439 3440 while (true) { 3441 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 3442 3443 if (num_claimed_nmethods == 0) { 3444 break; 3445 } 3446 3447 for (int i = 0; i < num_claimed_nmethods; i++) { 3448 clean_nmethod(claimed_nmethods[i]); 3449 } 3450 } 3451 } 3452 3453 void work_second_pass(uint worker_id) { 3454 CompiledMethod* nm; 3455 // Take care of postponed nmethods. 3456 while ((nm = claim_postponed_nmethod()) != NULL) { 3457 clean_nmethod_postponed(nm); 3458 } 3459 } 3460 }; 3461 3462 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 3463 3464 class G1KlassCleaningTask : public StackObj { 3465 volatile int _clean_klass_tree_claimed; 3466 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 3467 3468 public: 3469 G1KlassCleaningTask() : 3470 _clean_klass_tree_claimed(0), 3471 _klass_iterator() { 3472 } 3473 3474 private: 3475 bool claim_clean_klass_tree_task() { 3476 if (_clean_klass_tree_claimed) { 3477 return false; 3478 } 3479 3480 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0; 3481 } 3482 3483 InstanceKlass* claim_next_klass() { 3484 Klass* klass; 3485 do { 3486 klass =_klass_iterator.next_klass(); 3487 } while (klass != NULL && !klass->is_instance_klass()); 3488 3489 // this can be null so don't call InstanceKlass::cast 3490 return static_cast<InstanceKlass*>(klass); 3491 } 3492 3493 public: 3494 3495 void clean_klass(InstanceKlass* ik) { 3496 ik->clean_weak_instanceklass_links(); 3497 } 3498 3499 void work() { 3500 ResourceMark rm; 3501 3502 // One worker will clean the subklass/sibling klass tree. 3503 if (claim_clean_klass_tree_task()) { 3504 Klass::clean_subklass_tree(); 3505 } 3506 3507 // All workers will help cleaning the classes, 3508 InstanceKlass* klass; 3509 while ((klass = claim_next_klass()) != NULL) { 3510 clean_klass(klass); 3511 } 3512 } 3513 }; 3514 3515 class G1ResolvedMethodCleaningTask : public StackObj { 3516 volatile int _resolved_method_task_claimed; 3517 public: 3518 G1ResolvedMethodCleaningTask() : 3519 _resolved_method_task_claimed(0) {} 3520 3521 bool claim_resolved_method_task() { 3522 if (_resolved_method_task_claimed) { 3523 return false; 3524 } 3525 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0; 3526 } 3527 3528 // These aren't big, one thread can do it all. 3529 void work() { 3530 if (claim_resolved_method_task()) { 3531 ResolvedMethodTable::unlink(); 3532 } 3533 } 3534 }; 3535 3536 3537 // To minimize the remark pause times, the tasks below are done in parallel. 3538 class G1ParallelCleaningTask : public AbstractGangTask { 3539 private: 3540 bool _unloading_occurred; 3541 G1StringAndSymbolCleaningTask _string_symbol_task; 3542 G1CodeCacheUnloadingTask _code_cache_task; 3543 G1KlassCleaningTask _klass_cleaning_task; 3544 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task; 3545 3546 public: 3547 // The constructor is run in the VMThread. 3548 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) : 3549 AbstractGangTask("Parallel Cleaning"), 3550 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()), 3551 _code_cache_task(num_workers, is_alive, unloading_occurred), 3552 _klass_cleaning_task(), 3553 _unloading_occurred(unloading_occurred), 3554 _resolved_method_cleaning_task() { 3555 } 3556 3557 // The parallel work done by all worker threads. 3558 void work(uint worker_id) { 3559 // Do first pass of code cache cleaning. 3560 _code_cache_task.work_first_pass(worker_id); 3561 3562 // Let the threads mark that the first pass is done. 3563 _code_cache_task.barrier_mark(worker_id); 3564 3565 // Clean the Strings and Symbols. 3566 _string_symbol_task.work(worker_id); 3567 3568 // Clean unreferenced things in the ResolvedMethodTable 3569 _resolved_method_cleaning_task.work(); 3570 3571 // Wait for all workers to finish the first code cache cleaning pass. 3572 _code_cache_task.barrier_wait(worker_id); 3573 3574 // Do the second code cache cleaning work, which realize on 3575 // the liveness information gathered during the first pass. 3576 _code_cache_task.work_second_pass(worker_id); 3577 3578 // Clean all klasses that were not unloaded. 3579 // The weak metadata in klass doesn't need to be 3580 // processed if there was no unloading. 3581 if (_unloading_occurred) { 3582 _klass_cleaning_task.work(); 3583 } 3584 } 3585 }; 3586 3587 3588 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3589 bool class_unloading_occurred) { 3590 uint n_workers = workers()->active_workers(); 3591 3592 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred); 3593 workers()->run_task(&g1_unlink_task); 3594 } 3595 3596 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive, 3597 bool process_strings, 3598 bool process_symbols, 3599 bool process_string_dedup) { 3600 if (!process_strings && !process_symbols && !process_string_dedup) { 3601 // Nothing to clean. 3602 return; 3603 } 3604 3605 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup); 3606 workers()->run_task(&g1_unlink_task); 3607 3608 } 3609 3610 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3611 private: 3612 DirtyCardQueueSet* _queue; 3613 G1CollectedHeap* _g1h; 3614 public: 3615 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 3616 _queue(queue), _g1h(g1h) { } 3617 3618 virtual void work(uint worker_id) { 3619 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 3620 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 3621 3622 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3623 _queue->par_apply_closure_to_all_completed_buffers(&cl); 3624 3625 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3626 } 3627 }; 3628 3629 void G1CollectedHeap::redirty_logged_cards() { 3630 double redirty_logged_cards_start = os::elapsedTime(); 3631 3632 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 3633 dirty_card_queue_set().reset_for_par_iteration(); 3634 workers()->run_task(&redirty_task); 3635 3636 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3637 dcq.merge_bufferlists(&dirty_card_queue_set()); 3638 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 3639 3640 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3641 } 3642 3643 // Weak Reference Processing support 3644 3645 bool G1STWIsAliveClosure::do_object_b(oop p) { 3646 // An object is reachable if it is outside the collection set, 3647 // or is inside and copied. 3648 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3649 } 3650 3651 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3652 assert(obj != NULL, "must not be NULL"); 3653 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3654 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3655 // may falsely indicate that this is not the case here: however the collection set only 3656 // contains old regions when concurrent mark is not running. 3657 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3658 } 3659 3660 // Non Copying Keep Alive closure 3661 class G1KeepAliveClosure: public OopClosure { 3662 G1CollectedHeap*_g1h; 3663 public: 3664 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3665 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3666 void do_oop(oop* p) { 3667 oop obj = *p; 3668 assert(obj != NULL, "the caller should have filtered out NULL values"); 3669 3670 const InCSetState cset_state =_g1h->in_cset_state(obj); 3671 if (!cset_state.is_in_cset_or_humongous()) { 3672 return; 3673 } 3674 if (cset_state.is_in_cset()) { 3675 assert( obj->is_forwarded(), "invariant" ); 3676 *p = obj->forwardee(); 3677 } else { 3678 assert(!obj->is_forwarded(), "invariant" ); 3679 assert(cset_state.is_humongous(), 3680 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 3681 _g1h->set_humongous_is_live(obj); 3682 } 3683 } 3684 }; 3685 3686 // Copying Keep Alive closure - can be called from both 3687 // serial and parallel code as long as different worker 3688 // threads utilize different G1ParScanThreadState instances 3689 // and different queues. 3690 3691 class G1CopyingKeepAliveClosure: public OopClosure { 3692 G1CollectedHeap* _g1h; 3693 OopClosure* _copy_non_heap_obj_cl; 3694 G1ParScanThreadState* _par_scan_state; 3695 3696 public: 3697 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3698 OopClosure* non_heap_obj_cl, 3699 G1ParScanThreadState* pss): 3700 _g1h(g1h), 3701 _copy_non_heap_obj_cl(non_heap_obj_cl), 3702 _par_scan_state(pss) 3703 {} 3704 3705 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3706 virtual void do_oop( oop* p) { do_oop_work(p); } 3707 3708 template <class T> void do_oop_work(T* p) { 3709 oop obj = RawAccess<>::oop_load(p); 3710 3711 if (_g1h->is_in_cset_or_humongous(obj)) { 3712 // If the referent object has been forwarded (either copied 3713 // to a new location or to itself in the event of an 3714 // evacuation failure) then we need to update the reference 3715 // field and, if both reference and referent are in the G1 3716 // heap, update the RSet for the referent. 3717 // 3718 // If the referent has not been forwarded then we have to keep 3719 // it alive by policy. Therefore we have copy the referent. 3720 // 3721 // If the reference field is in the G1 heap then we can push 3722 // on the PSS queue. When the queue is drained (after each 3723 // phase of reference processing) the object and it's followers 3724 // will be copied, the reference field set to point to the 3725 // new location, and the RSet updated. Otherwise we need to 3726 // use the the non-heap or metadata closures directly to copy 3727 // the referent object and update the pointer, while avoiding 3728 // updating the RSet. 3729 3730 if (_g1h->is_in_g1_reserved(p)) { 3731 _par_scan_state->push_on_queue(p); 3732 } else { 3733 assert(!Metaspace::contains((const void*)p), 3734 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)); 3735 _copy_non_heap_obj_cl->do_oop(p); 3736 } 3737 } 3738 } 3739 }; 3740 3741 // Serial drain queue closure. Called as the 'complete_gc' 3742 // closure for each discovered list in some of the 3743 // reference processing phases. 3744 3745 class G1STWDrainQueueClosure: public VoidClosure { 3746 protected: 3747 G1CollectedHeap* _g1h; 3748 G1ParScanThreadState* _par_scan_state; 3749 3750 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3751 3752 public: 3753 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3754 _g1h(g1h), 3755 _par_scan_state(pss) 3756 { } 3757 3758 void do_void() { 3759 G1ParScanThreadState* const pss = par_scan_state(); 3760 pss->trim_queue(); 3761 } 3762 }; 3763 3764 // Parallel Reference Processing closures 3765 3766 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3767 // processing during G1 evacuation pauses. 3768 3769 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3770 private: 3771 G1CollectedHeap* _g1h; 3772 G1ParScanThreadStateSet* _pss; 3773 RefToScanQueueSet* _queues; 3774 WorkGang* _workers; 3775 uint _active_workers; 3776 3777 public: 3778 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3779 G1ParScanThreadStateSet* per_thread_states, 3780 WorkGang* workers, 3781 RefToScanQueueSet *task_queues, 3782 uint n_workers) : 3783 _g1h(g1h), 3784 _pss(per_thread_states), 3785 _queues(task_queues), 3786 _workers(workers), 3787 _active_workers(n_workers) 3788 { 3789 g1h->ref_processor_stw()->set_active_mt_degree(n_workers); 3790 } 3791 3792 // Executes the given task using concurrent marking worker threads. 3793 virtual void execute(ProcessTask& task); 3794 }; 3795 3796 // Gang task for possibly parallel reference processing 3797 3798 class G1STWRefProcTaskProxy: public AbstractGangTask { 3799 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3800 ProcessTask& _proc_task; 3801 G1CollectedHeap* _g1h; 3802 G1ParScanThreadStateSet* _pss; 3803 RefToScanQueueSet* _task_queues; 3804 ParallelTaskTerminator* _terminator; 3805 3806 public: 3807 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3808 G1CollectedHeap* g1h, 3809 G1ParScanThreadStateSet* per_thread_states, 3810 RefToScanQueueSet *task_queues, 3811 ParallelTaskTerminator* terminator) : 3812 AbstractGangTask("Process reference objects in parallel"), 3813 _proc_task(proc_task), 3814 _g1h(g1h), 3815 _pss(per_thread_states), 3816 _task_queues(task_queues), 3817 _terminator(terminator) 3818 {} 3819 3820 virtual void work(uint worker_id) { 3821 // The reference processing task executed by a single worker. 3822 ResourceMark rm; 3823 HandleMark hm; 3824 3825 G1STWIsAliveClosure is_alive(_g1h); 3826 3827 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3828 pss->set_ref_discoverer(NULL); 3829 3830 // Keep alive closure. 3831 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 3832 3833 // Complete GC closure 3834 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator); 3835 3836 // Call the reference processing task's work routine. 3837 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3838 3839 // Note we cannot assert that the refs array is empty here as not all 3840 // of the processing tasks (specifically phase2 - pp2_work) execute 3841 // the complete_gc closure (which ordinarily would drain the queue) so 3842 // the queue may not be empty. 3843 } 3844 }; 3845 3846 // Driver routine for parallel reference processing. 3847 // Creates an instance of the ref processing gang 3848 // task and has the worker threads execute it. 3849 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 3850 assert(_workers != NULL, "Need parallel worker threads."); 3851 3852 ParallelTaskTerminator terminator(_active_workers, _queues); 3853 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 3854 3855 _workers->run_task(&proc_task_proxy); 3856 } 3857 3858 // End of weak reference support closures 3859 3860 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3861 double ref_proc_start = os::elapsedTime(); 3862 3863 ReferenceProcessor* rp = _ref_processor_stw; 3864 assert(rp->discovery_enabled(), "should have been enabled"); 3865 3866 // Closure to test whether a referent is alive. 3867 G1STWIsAliveClosure is_alive(this); 3868 3869 // Even when parallel reference processing is enabled, the processing 3870 // of JNI refs is serial and performed serially by the current thread 3871 // rather than by a worker. The following PSS will be used for processing 3872 // JNI refs. 3873 3874 // Use only a single queue for this PSS. 3875 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3876 pss->set_ref_discoverer(NULL); 3877 assert(pss->queue_is_empty(), "pre-condition"); 3878 3879 // Keep alive closure. 3880 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss); 3881 3882 // Serial Complete GC closure 3883 G1STWDrainQueueClosure drain_queue(this, pss); 3884 3885 // Setup the soft refs policy... 3886 rp->setup_policy(false); 3887 3888 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times(); 3889 3890 ReferenceProcessorStats stats; 3891 if (!rp->processing_is_mt()) { 3892 // Serial reference processing... 3893 stats = rp->process_discovered_references(&is_alive, 3894 &keep_alive, 3895 &drain_queue, 3896 NULL, 3897 pt); 3898 } else { 3899 uint no_of_gc_workers = workers()->active_workers(); 3900 3901 // Parallel reference processing 3902 assert(no_of_gc_workers <= rp->max_num_queues(), 3903 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3904 no_of_gc_workers, rp->max_num_queues()); 3905 3906 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers); 3907 stats = rp->process_discovered_references(&is_alive, 3908 &keep_alive, 3909 &drain_queue, 3910 &par_task_executor, 3911 pt); 3912 } 3913 3914 _gc_tracer_stw->report_gc_reference_stats(stats); 3915 3916 // We have completed copying any necessary live referent objects. 3917 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3918 3919 make_pending_list_reachable(); 3920 3921 rp->verify_no_references_recorded(); 3922 3923 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3924 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3925 } 3926 3927 void G1CollectedHeap::make_pending_list_reachable() { 3928 if (collector_state()->in_initial_mark_gc()) { 3929 oop pll_head = Universe::reference_pending_list(); 3930 if (pll_head != NULL) { 3931 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3932 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3933 } 3934 } 3935 } 3936 3937 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3938 double merge_pss_time_start = os::elapsedTime(); 3939 per_thread_states->flush(); 3940 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 3941 } 3942 3943 void G1CollectedHeap::pre_evacuate_collection_set() { 3944 _expand_heap_after_alloc_failure = true; 3945 _evacuation_failed = false; 3946 3947 // Disable the hot card cache. 3948 _hot_card_cache->reset_hot_cache_claimed_index(); 3949 _hot_card_cache->set_use_cache(false); 3950 3951 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 3952 _preserved_marks_set.assert_empty(); 3953 3954 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3955 3956 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3957 if (collector_state()->in_initial_mark_gc()) { 3958 double start_clear_claimed_marks = os::elapsedTime(); 3959 3960 ClassLoaderDataGraph::clear_claimed_marks(); 3961 3962 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3963 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3964 } 3965 } 3966 3967 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3968 // Should G1EvacuationFailureALot be in effect for this GC? 3969 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3970 3971 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 3972 3973 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3974 3975 double start_par_time_sec = os::elapsedTime(); 3976 double end_par_time_sec; 3977 3978 { 3979 const uint n_workers = workers()->active_workers(); 3980 G1RootProcessor root_processor(this, n_workers); 3981 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 3982 3983 print_termination_stats_hdr(); 3984 3985 workers()->run_task(&g1_par_task); 3986 end_par_time_sec = os::elapsedTime(); 3987 3988 // Closing the inner scope will execute the destructor 3989 // for the G1RootProcessor object. We record the current 3990 // elapsed time before closing the scope so that time 3991 // taken for the destructor is NOT included in the 3992 // reported parallel time. 3993 } 3994 3995 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 3996 phase_times->record_par_time(par_time_ms); 3997 3998 double code_root_fixup_time_ms = 3999 (os::elapsedTime() - end_par_time_sec) * 1000.0; 4000 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 4001 } 4002 4003 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 4004 // Also cleans the card table from temporary duplicate detection information used 4005 // during UpdateRS/ScanRS. 4006 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 4007 4008 // Process any discovered reference objects - we have 4009 // to do this _before_ we retire the GC alloc regions 4010 // as we may have to copy some 'reachable' referent 4011 // objects (and their reachable sub-graphs) that were 4012 // not copied during the pause. 4013 process_discovered_references(per_thread_states); 4014 4015 // FIXME 4016 // CM's reference processing also cleans up the string and symbol tables. 4017 // Should we do that here also? We could, but it is a serial operation 4018 // and could significantly increase the pause time. 4019 4020 G1STWIsAliveClosure is_alive(this); 4021 G1KeepAliveClosure keep_alive(this); 4022 4023 { 4024 double start = os::elapsedTime(); 4025 4026 WeakProcessor::weak_oops_do(&is_alive, &keep_alive); 4027 4028 double time_ms = (os::elapsedTime() - start) * 1000.0; 4029 g1_policy()->phase_times()->record_weak_ref_proc_time(time_ms); 4030 } 4031 4032 if (G1StringDedup::is_enabled()) { 4033 double fixup_start = os::elapsedTime(); 4034 4035 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times()); 4036 4037 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 4038 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms); 4039 } 4040 4041 if (evacuation_failed()) { 4042 restore_after_evac_failure(); 4043 4044 // Reset the G1EvacuationFailureALot counters and flags 4045 // Note: the values are reset only when an actual 4046 // evacuation failure occurs. 4047 NOT_PRODUCT(reset_evacuation_should_fail();) 4048 } 4049 4050 _preserved_marks_set.assert_empty(); 4051 4052 _allocator->release_gc_alloc_regions(evacuation_info); 4053 4054 merge_per_thread_state_info(per_thread_states); 4055 4056 // Reset and re-enable the hot card cache. 4057 // Note the counts for the cards in the regions in the 4058 // collection set are reset when the collection set is freed. 4059 _hot_card_cache->reset_hot_cache(); 4060 _hot_card_cache->set_use_cache(true); 4061 4062 purge_code_root_memory(); 4063 4064 redirty_logged_cards(); 4065 #if COMPILER2_OR_JVMCI 4066 double start = os::elapsedTime(); 4067 DerivedPointerTable::update_pointers(); 4068 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 4069 #endif 4070 g1_policy()->print_age_table(); 4071 } 4072 4073 void G1CollectedHeap::record_obj_copy_mem_stats() { 4074 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 4075 4076 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 4077 create_g1_evac_summary(&_old_evac_stats)); 4078 } 4079 4080 void G1CollectedHeap::free_region(HeapRegion* hr, 4081 FreeRegionList* free_list, 4082 bool skip_remset, 4083 bool skip_hot_card_cache, 4084 bool locked) { 4085 assert(!hr->is_free(), "the region should not be free"); 4086 assert(!hr->is_empty(), "the region should not be empty"); 4087 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 4088 assert(free_list != NULL, "pre-condition"); 4089 4090 if (G1VerifyBitmaps) { 4091 MemRegion mr(hr->bottom(), hr->end()); 4092 concurrent_mark()->clear_range_in_prev_bitmap(mr); 4093 } 4094 4095 // Clear the card counts for this region. 4096 // Note: we only need to do this if the region is not young 4097 // (since we don't refine cards in young regions). 4098 if (!skip_hot_card_cache && !hr->is_young()) { 4099 _hot_card_cache->reset_card_counts(hr); 4100 } 4101 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 4102 _g1_policy->remset_tracker()->update_at_free(hr); 4103 free_list->add_ordered(hr); 4104 } 4105 4106 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4107 FreeRegionList* free_list) { 4108 assert(hr->is_humongous(), "this is only for humongous regions"); 4109 assert(free_list != NULL, "pre-condition"); 4110 hr->clear_humongous(); 4111 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */); 4112 } 4113 4114 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 4115 const uint humongous_regions_removed) { 4116 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 4117 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4118 _old_set.bulk_remove(old_regions_removed); 4119 _humongous_set.bulk_remove(humongous_regions_removed); 4120 } 4121 4122 } 4123 4124 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4125 assert(list != NULL, "list can't be null"); 4126 if (!list->is_empty()) { 4127 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4128 _hrm.insert_list_into_free_list(list); 4129 } 4130 } 4131 4132 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4133 decrease_used(bytes); 4134 } 4135 4136 class G1FreeCollectionSetTask : public AbstractGangTask { 4137 private: 4138 4139 // Closure applied to all regions in the collection set to do work that needs to 4140 // be done serially in a single thread. 4141 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 4142 private: 4143 EvacuationInfo* _evacuation_info; 4144 const size_t* _surviving_young_words; 4145 4146 // Bytes used in successfully evacuated regions before the evacuation. 4147 size_t _before_used_bytes; 4148 // Bytes used in unsucessfully evacuated regions before the evacuation 4149 size_t _after_used_bytes; 4150 4151 size_t _bytes_allocated_in_old_since_last_gc; 4152 4153 size_t _failure_used_words; 4154 size_t _failure_waste_words; 4155 4156 FreeRegionList _local_free_list; 4157 public: 4158 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4159 HeapRegionClosure(), 4160 _evacuation_info(evacuation_info), 4161 _surviving_young_words(surviving_young_words), 4162 _before_used_bytes(0), 4163 _after_used_bytes(0), 4164 _bytes_allocated_in_old_since_last_gc(0), 4165 _failure_used_words(0), 4166 _failure_waste_words(0), 4167 _local_free_list("Local Region List for CSet Freeing") { 4168 } 4169 4170 virtual bool do_heap_region(HeapRegion* r) { 4171 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4172 4173 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 4174 g1h->clear_in_cset(r); 4175 4176 if (r->is_young()) { 4177 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(), 4178 "Young index %d is wrong for region %u of type %s with %u young regions", 4179 r->young_index_in_cset(), 4180 r->hrm_index(), 4181 r->get_type_str(), 4182 g1h->collection_set()->young_region_length()); 4183 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 4184 r->record_surv_words_in_group(words_survived); 4185 } 4186 4187 if (!r->evacuation_failed()) { 4188 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4189 _before_used_bytes += r->used(); 4190 g1h->free_region(r, 4191 &_local_free_list, 4192 true, /* skip_remset */ 4193 true, /* skip_hot_card_cache */ 4194 true /* locked */); 4195 } else { 4196 r->uninstall_surv_rate_group(); 4197 r->set_young_index_in_cset(-1); 4198 r->set_evacuation_failed(false); 4199 // When moving a young gen region to old gen, we "allocate" that whole region 4200 // there. This is in addition to any already evacuated objects. Notify the 4201 // policy about that. 4202 // Old gen regions do not cause an additional allocation: both the objects 4203 // still in the region and the ones already moved are accounted for elsewhere. 4204 if (r->is_young()) { 4205 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4206 } 4207 // The region is now considered to be old. 4208 r->set_old(); 4209 // Do some allocation statistics accounting. Regions that failed evacuation 4210 // are always made old, so there is no need to update anything in the young 4211 // gen statistics, but we need to update old gen statistics. 4212 size_t used_words = r->marked_bytes() / HeapWordSize; 4213 4214 _failure_used_words += used_words; 4215 _failure_waste_words += HeapRegion::GrainWords - used_words; 4216 4217 g1h->old_set_add(r); 4218 _after_used_bytes += r->used(); 4219 } 4220 return false; 4221 } 4222 4223 void complete_work() { 4224 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4225 4226 _evacuation_info->set_regions_freed(_local_free_list.length()); 4227 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4228 4229 g1h->prepend_to_freelist(&_local_free_list); 4230 g1h->decrement_summary_bytes(_before_used_bytes); 4231 4232 G1Policy* policy = g1h->g1_policy(); 4233 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4234 4235 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4236 } 4237 }; 4238 4239 G1CollectionSet* _collection_set; 4240 G1SerialFreeCollectionSetClosure _cl; 4241 const size_t* _surviving_young_words; 4242 4243 size_t _rs_lengths; 4244 4245 volatile jint _serial_work_claim; 4246 4247 struct WorkItem { 4248 uint region_idx; 4249 bool is_young; 4250 bool evacuation_failed; 4251 4252 WorkItem(HeapRegion* r) { 4253 region_idx = r->hrm_index(); 4254 is_young = r->is_young(); 4255 evacuation_failed = r->evacuation_failed(); 4256 } 4257 }; 4258 4259 volatile size_t _parallel_work_claim; 4260 size_t _num_work_items; 4261 WorkItem* _work_items; 4262 4263 void do_serial_work() { 4264 // Need to grab the lock to be allowed to modify the old region list. 4265 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4266 _collection_set->iterate(&_cl); 4267 } 4268 4269 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4270 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4271 4272 HeapRegion* r = g1h->region_at(region_idx); 4273 assert(!g1h->is_on_master_free_list(r), "sanity"); 4274 4275 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths); 4276 4277 if (!is_young) { 4278 g1h->_hot_card_cache->reset_card_counts(r); 4279 } 4280 4281 if (!evacuation_failed) { 4282 r->rem_set()->clear_locked(); 4283 } 4284 } 4285 4286 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4287 private: 4288 size_t _cur_idx; 4289 WorkItem* _work_items; 4290 public: 4291 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4292 4293 virtual bool do_heap_region(HeapRegion* r) { 4294 _work_items[_cur_idx++] = WorkItem(r); 4295 return false; 4296 } 4297 }; 4298 4299 void prepare_work() { 4300 G1PrepareFreeCollectionSetClosure cl(_work_items); 4301 _collection_set->iterate(&cl); 4302 } 4303 4304 void complete_work() { 4305 _cl.complete_work(); 4306 4307 G1Policy* policy = G1CollectedHeap::heap()->g1_policy(); 4308 policy->record_max_rs_lengths(_rs_lengths); 4309 policy->cset_regions_freed(); 4310 } 4311 public: 4312 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4313 AbstractGangTask("G1 Free Collection Set"), 4314 _cl(evacuation_info, surviving_young_words), 4315 _collection_set(collection_set), 4316 _surviving_young_words(surviving_young_words), 4317 _serial_work_claim(0), 4318 _rs_lengths(0), 4319 _parallel_work_claim(0), 4320 _num_work_items(collection_set->region_length()), 4321 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4322 prepare_work(); 4323 } 4324 4325 ~G1FreeCollectionSetTask() { 4326 complete_work(); 4327 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4328 } 4329 4330 // Chunk size for work distribution. The chosen value has been determined experimentally 4331 // to be a good tradeoff between overhead and achievable parallelism. 4332 static uint chunk_size() { return 32; } 4333 4334 virtual void work(uint worker_id) { 4335 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4336 4337 // Claim serial work. 4338 if (_serial_work_claim == 0) { 4339 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4340 if (value == 0) { 4341 double serial_time = os::elapsedTime(); 4342 do_serial_work(); 4343 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4344 } 4345 } 4346 4347 // Start parallel work. 4348 double young_time = 0.0; 4349 bool has_young_time = false; 4350 double non_young_time = 0.0; 4351 bool has_non_young_time = false; 4352 4353 while (true) { 4354 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4355 size_t cur = end - chunk_size(); 4356 4357 if (cur >= _num_work_items) { 4358 break; 4359 } 4360 4361 double start_time = os::elapsedTime(); 4362 4363 end = MIN2(end, _num_work_items); 4364 4365 for (; cur < end; cur++) { 4366 bool is_young = _work_items[cur].is_young; 4367 4368 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4369 4370 double end_time = os::elapsedTime(); 4371 double time_taken = end_time - start_time; 4372 if (is_young) { 4373 young_time += time_taken; 4374 has_young_time = true; 4375 } else { 4376 non_young_time += time_taken; 4377 has_non_young_time = true; 4378 } 4379 start_time = end_time; 4380 } 4381 } 4382 4383 if (has_young_time) { 4384 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4385 } 4386 if (has_non_young_time) { 4387 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4388 } 4389 } 4390 }; 4391 4392 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4393 _eden.clear(); 4394 4395 double free_cset_start_time = os::elapsedTime(); 4396 4397 { 4398 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U); 4399 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4400 4401 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4402 4403 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4404 cl.name(), 4405 num_workers, 4406 _collection_set.region_length()); 4407 workers()->run_task(&cl, num_workers); 4408 } 4409 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4410 4411 collection_set->clear(); 4412 } 4413 4414 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4415 private: 4416 FreeRegionList* _free_region_list; 4417 HeapRegionSet* _proxy_set; 4418 uint _humongous_objects_reclaimed; 4419 uint _humongous_regions_reclaimed; 4420 size_t _freed_bytes; 4421 public: 4422 4423 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4424 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4425 } 4426 4427 virtual bool do_heap_region(HeapRegion* r) { 4428 if (!r->is_starts_humongous()) { 4429 return false; 4430 } 4431 4432 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4433 4434 oop obj = (oop)r->bottom(); 4435 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4436 4437 // The following checks whether the humongous object is live are sufficient. 4438 // The main additional check (in addition to having a reference from the roots 4439 // or the young gen) is whether the humongous object has a remembered set entry. 4440 // 4441 // A humongous object cannot be live if there is no remembered set for it 4442 // because: 4443 // - there can be no references from within humongous starts regions referencing 4444 // the object because we never allocate other objects into them. 4445 // (I.e. there are no intra-region references that may be missed by the 4446 // remembered set) 4447 // - as soon there is a remembered set entry to the humongous starts region 4448 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4449 // until the end of a concurrent mark. 4450 // 4451 // It is not required to check whether the object has been found dead by marking 4452 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4453 // all objects allocated during that time are considered live. 4454 // SATB marking is even more conservative than the remembered set. 4455 // So if at this point in the collection there is no remembered set entry, 4456 // nobody has a reference to it. 4457 // At the start of collection we flush all refinement logs, and remembered sets 4458 // are completely up-to-date wrt to references to the humongous object. 4459 // 4460 // Other implementation considerations: 4461 // - never consider object arrays at this time because they would pose 4462 // considerable effort for cleaning up the the remembered sets. This is 4463 // required because stale remembered sets might reference locations that 4464 // are currently allocated into. 4465 uint region_idx = r->hrm_index(); 4466 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4467 !r->rem_set()->is_empty()) { 4468 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", 4469 region_idx, 4470 (size_t)obj->size() * HeapWordSize, 4471 p2i(r->bottom()), 4472 r->rem_set()->occupied(), 4473 r->rem_set()->strong_code_roots_list_length(), 4474 next_bitmap->is_marked(r->bottom()), 4475 g1h->is_humongous_reclaim_candidate(region_idx), 4476 obj->is_typeArray() 4477 ); 4478 return false; 4479 } 4480 4481 guarantee(obj->is_typeArray(), 4482 "Only eagerly reclaiming type arrays is supported, but the object " 4483 PTR_FORMAT " is not.", p2i(r->bottom())); 4484 4485 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", 4486 region_idx, 4487 (size_t)obj->size() * HeapWordSize, 4488 p2i(r->bottom()), 4489 r->rem_set()->occupied(), 4490 r->rem_set()->strong_code_roots_list_length(), 4491 next_bitmap->is_marked(r->bottom()), 4492 g1h->is_humongous_reclaim_candidate(region_idx), 4493 obj->is_typeArray() 4494 ); 4495 4496 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4497 cm->humongous_object_eagerly_reclaimed(r); 4498 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4499 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4500 region_idx, 4501 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4502 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4503 _humongous_objects_reclaimed++; 4504 do { 4505 HeapRegion* next = g1h->next_region_in_humongous(r); 4506 _freed_bytes += r->used(); 4507 r->set_containing_set(NULL); 4508 _humongous_regions_reclaimed++; 4509 g1h->free_humongous_region(r, _free_region_list); 4510 r = next; 4511 } while (r != NULL); 4512 4513 return false; 4514 } 4515 4516 uint humongous_objects_reclaimed() { 4517 return _humongous_objects_reclaimed; 4518 } 4519 4520 uint humongous_regions_reclaimed() { 4521 return _humongous_regions_reclaimed; 4522 } 4523 4524 size_t bytes_freed() const { 4525 return _freed_bytes; 4526 } 4527 }; 4528 4529 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4530 assert_at_safepoint_on_vm_thread(); 4531 4532 if (!G1EagerReclaimHumongousObjects || 4533 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4534 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4535 return; 4536 } 4537 4538 double start_time = os::elapsedTime(); 4539 4540 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4541 4542 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4543 heap_region_iterate(&cl); 4544 4545 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4546 4547 G1HRPrinter* hrp = hr_printer(); 4548 if (hrp->is_active()) { 4549 FreeRegionListIterator iter(&local_cleanup_list); 4550 while (iter.more_available()) { 4551 HeapRegion* hr = iter.get_next(); 4552 hrp->cleanup(hr); 4553 } 4554 } 4555 4556 prepend_to_freelist(&local_cleanup_list); 4557 decrement_summary_bytes(cl.bytes_freed()); 4558 4559 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4560 cl.humongous_objects_reclaimed()); 4561 } 4562 4563 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4564 public: 4565 virtual bool do_heap_region(HeapRegion* r) { 4566 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4567 G1CollectedHeap::heap()->clear_in_cset(r); 4568 r->set_young_index_in_cset(-1); 4569 return false; 4570 } 4571 }; 4572 4573 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4574 G1AbandonCollectionSetClosure cl; 4575 collection_set->iterate(&cl); 4576 4577 collection_set->clear(); 4578 collection_set->stop_incremental_building(); 4579 } 4580 4581 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4582 return _allocator->is_retained_old_region(hr); 4583 } 4584 4585 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4586 _eden.add(hr); 4587 _g1_policy->set_region_eden(hr); 4588 } 4589 4590 #ifdef ASSERT 4591 4592 class NoYoungRegionsClosure: public HeapRegionClosure { 4593 private: 4594 bool _success; 4595 public: 4596 NoYoungRegionsClosure() : _success(true) { } 4597 bool do_heap_region(HeapRegion* r) { 4598 if (r->is_young()) { 4599 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4600 p2i(r->bottom()), p2i(r->end())); 4601 _success = false; 4602 } 4603 return false; 4604 } 4605 bool success() { return _success; } 4606 }; 4607 4608 bool G1CollectedHeap::check_young_list_empty() { 4609 bool ret = (young_regions_count() == 0); 4610 4611 NoYoungRegionsClosure closure; 4612 heap_region_iterate(&closure); 4613 ret = ret && closure.success(); 4614 4615 return ret; 4616 } 4617 4618 #endif // ASSERT 4619 4620 class TearDownRegionSetsClosure : public HeapRegionClosure { 4621 private: 4622 HeapRegionSet *_old_set; 4623 4624 public: 4625 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4626 4627 bool do_heap_region(HeapRegion* r) { 4628 if (r->is_old()) { 4629 _old_set->remove(r); 4630 } else if(r->is_young()) { 4631 r->uninstall_surv_rate_group(); 4632 } else { 4633 // We ignore free regions, we'll empty the free list afterwards. 4634 // We ignore humongous regions, we're not tearing down the 4635 // humongous regions set. 4636 assert(r->is_free() || r->is_humongous(), 4637 "it cannot be another type"); 4638 } 4639 return false; 4640 } 4641 4642 ~TearDownRegionSetsClosure() { 4643 assert(_old_set->is_empty(), "post-condition"); 4644 } 4645 }; 4646 4647 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4648 assert_at_safepoint_on_vm_thread(); 4649 4650 if (!free_list_only) { 4651 TearDownRegionSetsClosure cl(&_old_set); 4652 heap_region_iterate(&cl); 4653 4654 // Note that emptying the _young_list is postponed and instead done as 4655 // the first step when rebuilding the regions sets again. The reason for 4656 // this is that during a full GC string deduplication needs to know if 4657 // a collected region was young or old when the full GC was initiated. 4658 } 4659 _hrm.remove_all_free_regions(); 4660 } 4661 4662 void G1CollectedHeap::increase_used(size_t bytes) { 4663 _summary_bytes_used += bytes; 4664 } 4665 4666 void G1CollectedHeap::decrease_used(size_t bytes) { 4667 assert(_summary_bytes_used >= bytes, 4668 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4669 _summary_bytes_used, bytes); 4670 _summary_bytes_used -= bytes; 4671 } 4672 4673 void G1CollectedHeap::set_used(size_t bytes) { 4674 _summary_bytes_used = bytes; 4675 } 4676 4677 class RebuildRegionSetsClosure : public HeapRegionClosure { 4678 private: 4679 bool _free_list_only; 4680 HeapRegionSet* _old_set; 4681 HeapRegionManager* _hrm; 4682 size_t _total_used; 4683 4684 public: 4685 RebuildRegionSetsClosure(bool free_list_only, 4686 HeapRegionSet* old_set, HeapRegionManager* hrm) : 4687 _free_list_only(free_list_only), 4688 _old_set(old_set), _hrm(hrm), _total_used(0) { 4689 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4690 if (!free_list_only) { 4691 assert(_old_set->is_empty(), "pre-condition"); 4692 } 4693 } 4694 4695 bool do_heap_region(HeapRegion* r) { 4696 // After full GC, no region should have a remembered set. 4697 r->rem_set()->clear(true); 4698 if (r->is_empty()) { 4699 // Add free regions to the free list 4700 r->set_free(); 4701 _hrm->insert_into_free_list(r); 4702 } else if (!_free_list_only) { 4703 4704 if (r->is_humongous()) { 4705 // We ignore humongous regions. We left the humongous set unchanged. 4706 } else { 4707 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4708 // We now move all (non-humongous, non-old) regions to old gen, and register them as such. 4709 r->move_to_old(); 4710 _old_set->add(r); 4711 } 4712 _total_used += r->used(); 4713 } 4714 4715 return false; 4716 } 4717 4718 size_t total_used() { 4719 return _total_used; 4720 } 4721 }; 4722 4723 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4724 assert_at_safepoint_on_vm_thread(); 4725 4726 if (!free_list_only) { 4727 _eden.clear(); 4728 _survivor.clear(); 4729 } 4730 4731 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 4732 heap_region_iterate(&cl); 4733 4734 if (!free_list_only) { 4735 set_used(cl.total_used()); 4736 if (_archive_allocator != NULL) { 4737 _archive_allocator->clear_used(); 4738 } 4739 } 4740 assert(used_unlocked() == recalculate_used(), 4741 "inconsistent used_unlocked(), " 4742 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 4743 used_unlocked(), recalculate_used()); 4744 } 4745 4746 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 4747 HeapRegion* hr = heap_region_containing(p); 4748 return hr->is_in(p); 4749 } 4750 4751 // Methods for the mutator alloc region 4752 4753 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4754 bool force) { 4755 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4756 bool should_allocate = g1_policy()->should_allocate_mutator_region(); 4757 if (force || should_allocate) { 4758 HeapRegion* new_alloc_region = new_region(word_size, 4759 false /* is_old */, 4760 false /* do_expand */); 4761 if (new_alloc_region != NULL) { 4762 set_region_short_lived_locked(new_alloc_region); 4763 _hr_printer.alloc(new_alloc_region, !should_allocate); 4764 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4765 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region); 4766 return new_alloc_region; 4767 } 4768 } 4769 return NULL; 4770 } 4771 4772 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4773 size_t allocated_bytes) { 4774 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4775 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4776 4777 collection_set()->add_eden_region(alloc_region); 4778 increase_used(allocated_bytes); 4779 _hr_printer.retire(alloc_region); 4780 // We update the eden sizes here, when the region is retired, 4781 // instead of when it's allocated, since this is the point that its 4782 // used space has been recored in _summary_bytes_used. 4783 g1mm()->update_eden_size(); 4784 } 4785 4786 // Methods for the GC alloc regions 4787 4788 bool G1CollectedHeap::has_more_regions(InCSetState dest) { 4789 if (dest.is_old()) { 4790 return true; 4791 } else { 4792 return survivor_regions_count() < g1_policy()->max_survivor_regions(); 4793 } 4794 } 4795 4796 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) { 4797 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4798 4799 if (!has_more_regions(dest)) { 4800 return NULL; 4801 } 4802 4803 const bool is_survivor = dest.is_young(); 4804 4805 HeapRegion* new_alloc_region = new_region(word_size, 4806 !is_survivor, 4807 true /* do_expand */); 4808 if (new_alloc_region != NULL) { 4809 if (is_survivor) { 4810 new_alloc_region->set_survivor(); 4811 _survivor.add(new_alloc_region); 4812 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4813 } else { 4814 new_alloc_region->set_old(); 4815 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4816 } 4817 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region); 4818 _hr_printer.alloc(new_alloc_region); 4819 bool during_im = collector_state()->in_initial_mark_gc(); 4820 new_alloc_region->note_start_of_copying(during_im); 4821 return new_alloc_region; 4822 } 4823 return NULL; 4824 } 4825 4826 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4827 size_t allocated_bytes, 4828 InCSetState dest) { 4829 bool during_im = collector_state()->in_initial_mark_gc(); 4830 alloc_region->note_end_of_copying(during_im); 4831 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 4832 if (dest.is_old()) { 4833 _old_set.add(alloc_region); 4834 } 4835 _hr_printer.retire(alloc_region); 4836 } 4837 4838 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4839 bool expanded = false; 4840 uint index = _hrm.find_highest_free(&expanded); 4841 4842 if (index != G1_NO_HRM_INDEX) { 4843 if (expanded) { 4844 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4845 HeapRegion::GrainWords * HeapWordSize); 4846 } 4847 _hrm.allocate_free_regions_starting_at(index, 1); 4848 return region_at(index); 4849 } 4850 return NULL; 4851 } 4852 4853 // Optimized nmethod scanning 4854 4855 class RegisterNMethodOopClosure: public OopClosure { 4856 G1CollectedHeap* _g1h; 4857 nmethod* _nm; 4858 4859 template <class T> void do_oop_work(T* p) { 4860 T heap_oop = RawAccess<>::oop_load(p); 4861 if (!CompressedOops::is_null(heap_oop)) { 4862 oop obj = CompressedOops::decode_not_null(heap_oop); 4863 HeapRegion* hr = _g1h->heap_region_containing(obj); 4864 assert(!hr->is_continues_humongous(), 4865 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4866 " starting at " HR_FORMAT, 4867 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4868 4869 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4870 hr->add_strong_code_root_locked(_nm); 4871 } 4872 } 4873 4874 public: 4875 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4876 _g1h(g1h), _nm(nm) {} 4877 4878 void do_oop(oop* p) { do_oop_work(p); } 4879 void do_oop(narrowOop* p) { do_oop_work(p); } 4880 }; 4881 4882 class UnregisterNMethodOopClosure: public OopClosure { 4883 G1CollectedHeap* _g1h; 4884 nmethod* _nm; 4885 4886 template <class T> void do_oop_work(T* p) { 4887 T heap_oop = RawAccess<>::oop_load(p); 4888 if (!CompressedOops::is_null(heap_oop)) { 4889 oop obj = CompressedOops::decode_not_null(heap_oop); 4890 HeapRegion* hr = _g1h->heap_region_containing(obj); 4891 assert(!hr->is_continues_humongous(), 4892 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4893 " starting at " HR_FORMAT, 4894 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4895 4896 hr->remove_strong_code_root(_nm); 4897 } 4898 } 4899 4900 public: 4901 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4902 _g1h(g1h), _nm(nm) {} 4903 4904 void do_oop(oop* p) { do_oop_work(p); } 4905 void do_oop(narrowOop* p) { do_oop_work(p); } 4906 }; 4907 4908 // Returns true if the reference points to an object that 4909 // can move in an incremental collection. 4910 bool G1CollectedHeap::is_scavengable(oop obj) { 4911 HeapRegion* hr = heap_region_containing(obj); 4912 return !hr->is_pinned(); 4913 } 4914 4915 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4916 guarantee(nm != NULL, "sanity"); 4917 RegisterNMethodOopClosure reg_cl(this, nm); 4918 nm->oops_do(®_cl); 4919 } 4920 4921 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4922 guarantee(nm != NULL, "sanity"); 4923 UnregisterNMethodOopClosure reg_cl(this, nm); 4924 nm->oops_do(®_cl, true); 4925 } 4926 4927 void G1CollectedHeap::purge_code_root_memory() { 4928 double purge_start = os::elapsedTime(); 4929 G1CodeRootSet::purge(); 4930 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4931 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4932 } 4933 4934 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4935 G1CollectedHeap* _g1h; 4936 4937 public: 4938 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4939 _g1h(g1h) {} 4940 4941 void do_code_blob(CodeBlob* cb) { 4942 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4943 if (nm == NULL) { 4944 return; 4945 } 4946 4947 if (ScavengeRootsInCode) { 4948 _g1h->register_nmethod(nm); 4949 } 4950 } 4951 }; 4952 4953 void G1CollectedHeap::rebuild_strong_code_roots() { 4954 RebuildStrongCodeRootClosure blob_cl(this); 4955 CodeCache::blobs_do(&blob_cl); 4956 } 4957 4958 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4959 GrowableArray<GCMemoryManager*> memory_managers(2); 4960 memory_managers.append(&_memory_manager); 4961 memory_managers.append(&_full_gc_memory_manager); 4962 return memory_managers; 4963 } 4964 4965 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4966 GrowableArray<MemoryPool*> memory_pools(3); 4967 memory_pools.append(_eden_pool); 4968 memory_pools.append(_survivor_pool); 4969 memory_pools.append(_old_pool); 4970 return memory_pools; 4971 }