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/bufferingOopClosure.hpp" 32 #include "gc/g1/concurrentMarkThread.inline.hpp" 33 #include "gc/g1/g1Allocator.inline.hpp" 34 #include "gc/g1/g1CollectedHeap.inline.hpp" 35 #include "gc/g1/g1CollectionSet.hpp" 36 #include "gc/g1/g1CollectorPolicy.hpp" 37 #include "gc/g1/g1CollectorState.hpp" 38 #include "gc/g1/g1ConcurrentRefine.hpp" 39 #include "gc/g1/g1ConcurrentRefineThread.hpp" 40 #include "gc/g1/g1DefaultPolicy.hpp" 41 #include "gc/g1/g1EvacStats.inline.hpp" 42 #include "gc/g1/g1FullCollector.hpp" 43 #include "gc/g1/g1GCPhaseTimes.hpp" 44 #include "gc/g1/g1HeapSizingPolicy.hpp" 45 #include "gc/g1/g1HeapTransition.hpp" 46 #include "gc/g1/g1HeapVerifier.hpp" 47 #include "gc/g1/g1HotCardCache.hpp" 48 #include "gc/g1/g1MemoryPool.hpp" 49 #include "gc/g1/g1OopClosures.inline.hpp" 50 #include "gc/g1/g1ParScanThreadState.inline.hpp" 51 #include "gc/g1/g1Policy.hpp" 52 #include "gc/g1/g1RegionToSpaceMapper.hpp" 53 #include "gc/g1/g1RemSet.hpp" 54 #include "gc/g1/g1RootClosures.hpp" 55 #include "gc/g1/g1RootProcessor.hpp" 56 #include "gc/g1/g1StringDedup.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.inline.hpp" 67 #include "gc/shared/gcTimer.hpp" 68 #include "gc/shared/gcTrace.hpp" 69 #include "gc/shared/gcTraceTime.inline.hpp" 70 #include "gc/shared/generationSpec.hpp" 71 #include "gc/shared/isGCActiveMark.hpp" 72 #include "gc/shared/preservedMarks.inline.hpp" 73 #include "gc/shared/suspendibleThreadSet.hpp" 74 #include "gc/shared/referenceProcessor.inline.hpp" 75 #include "gc/shared/taskqueue.inline.hpp" 76 #include "gc/shared/weakProcessor.hpp" 77 #include "logging/log.hpp" 78 #include "memory/allocation.hpp" 79 #include "memory/iterator.hpp" 80 #include "memory/resourceArea.hpp" 81 #include "oops/oop.inline.hpp" 82 #include "prims/resolvedMethodTable.hpp" 83 #include "runtime/atomic.hpp" 84 #include "runtime/init.hpp" 85 #include "runtime/orderAccess.inline.hpp" 86 #include "runtime/threadSMR.hpp" 87 #include "runtime/vmThread.hpp" 88 #include "utilities/align.hpp" 89 #include "utilities/globalDefinitions.hpp" 90 #include "utilities/stack.inline.hpp" 91 92 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 93 94 // INVARIANTS/NOTES 95 // 96 // All allocation activity covered by the G1CollectedHeap interface is 97 // serialized by acquiring the HeapLock. This happens in mem_allocate 98 // and allocate_new_tlab, which are the "entry" points to the 99 // allocation code from the rest of the JVM. (Note that this does not 100 // apply to TLAB allocation, which is not part of this interface: it 101 // is done by clients of this interface.) 102 103 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 104 private: 105 size_t _num_dirtied; 106 G1CollectedHeap* _g1h; 107 G1CardTable* _g1_ct; 108 109 HeapRegion* region_for_card(jbyte* card_ptr) const { 110 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr)); 111 } 112 113 bool will_become_free(HeapRegion* hr) const { 114 // A region will be freed by free_collection_set if the region is in the 115 // collection set and has not had an evacuation failure. 116 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 117 } 118 119 public: 120 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(), 121 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { } 122 123 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 124 HeapRegion* hr = region_for_card(card_ptr); 125 126 // Should only dirty cards in regions that won't be freed. 127 if (!will_become_free(hr)) { 128 *card_ptr = G1CardTable::dirty_card_val(); 129 _num_dirtied++; 130 } 131 132 return true; 133 } 134 135 size_t num_dirtied() const { return _num_dirtied; } 136 }; 137 138 139 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 140 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 141 } 142 143 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 144 // The from card cache is not the memory that is actually committed. So we cannot 145 // take advantage of the zero_filled parameter. 146 reset_from_card_cache(start_idx, num_regions); 147 } 148 149 150 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 151 MemRegion mr) { 152 return new HeapRegion(hrs_index, bot(), mr); 153 } 154 155 // Private methods. 156 157 HeapRegion* 158 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 159 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 160 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 161 if (!_secondary_free_list.is_empty()) { 162 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 163 "secondary_free_list has %u entries", 164 _secondary_free_list.length()); 165 // It looks as if there are free regions available on the 166 // secondary_free_list. Let's move them to the free_list and try 167 // again to allocate from it. 168 append_secondary_free_list(); 169 170 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 171 "empty we should have moved at least one entry to the free_list"); 172 HeapRegion* res = _hrm.allocate_free_region(is_old); 173 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 174 "allocated " HR_FORMAT " from secondary_free_list", 175 HR_FORMAT_PARAMS(res)); 176 return res; 177 } 178 179 // Wait here until we get notified either when (a) there are no 180 // more free regions coming or (b) some regions have been moved on 181 // the secondary_free_list. 182 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 183 } 184 185 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 186 "could not allocate from secondary_free_list"); 187 return NULL; 188 } 189 190 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 191 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 192 "the only time we use this to allocate a humongous region is " 193 "when we are allocating a single humongous region"); 194 195 HeapRegion* res; 196 if (G1StressConcRegionFreeing) { 197 if (!_secondary_free_list.is_empty()) { 198 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 199 "forced to look at the secondary_free_list"); 200 res = new_region_try_secondary_free_list(is_old); 201 if (res != NULL) { 202 return res; 203 } 204 } 205 } 206 207 res = _hrm.allocate_free_region(is_old); 208 209 if (res == NULL) { 210 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 211 "res == NULL, trying the secondary_free_list"); 212 res = new_region_try_secondary_free_list(is_old); 213 } 214 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 215 // Currently, only attempts to allocate GC alloc regions set 216 // do_expand to true. So, we should only reach here during a 217 // safepoint. If this assumption changes we might have to 218 // reconsider the use of _expand_heap_after_alloc_failure. 219 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 220 221 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 222 word_size * HeapWordSize); 223 224 if (expand(word_size * HeapWordSize)) { 225 // Given that expand() succeeded in expanding the heap, and we 226 // always expand the heap by an amount aligned to the heap 227 // region size, the free list should in theory not be empty. 228 // In either case allocate_free_region() will check for NULL. 229 res = _hrm.allocate_free_region(is_old); 230 } else { 231 _expand_heap_after_alloc_failure = false; 232 } 233 } 234 return res; 235 } 236 237 HeapWord* 238 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 239 uint num_regions, 240 size_t word_size) { 241 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 242 assert(is_humongous(word_size), "word_size should be humongous"); 243 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 244 245 // Index of last region in the series. 246 uint last = first + num_regions - 1; 247 248 // We need to initialize the region(s) we just discovered. This is 249 // a bit tricky given that it can happen concurrently with 250 // refinement threads refining cards on these regions and 251 // potentially wanting to refine the BOT as they are scanning 252 // those cards (this can happen shortly after a cleanup; see CR 253 // 6991377). So we have to set up the region(s) carefully and in 254 // a specific order. 255 256 // The word size sum of all the regions we will allocate. 257 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 258 assert(word_size <= word_size_sum, "sanity"); 259 260 // This will be the "starts humongous" region. 261 HeapRegion* first_hr = region_at(first); 262 // The header of the new object will be placed at the bottom of 263 // the first region. 264 HeapWord* new_obj = first_hr->bottom(); 265 // This will be the new top of the new object. 266 HeapWord* obj_top = new_obj + word_size; 267 268 // First, we need to zero the header of the space that we will be 269 // allocating. When we update top further down, some refinement 270 // threads might try to scan the region. By zeroing the header we 271 // ensure that any thread that will try to scan the region will 272 // come across the zero klass word and bail out. 273 // 274 // NOTE: It would not have been correct to have used 275 // CollectedHeap::fill_with_object() and make the space look like 276 // an int array. The thread that is doing the allocation will 277 // later update the object header to a potentially different array 278 // type and, for a very short period of time, the klass and length 279 // fields will be inconsistent. This could cause a refinement 280 // thread to calculate the object size incorrectly. 281 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 282 283 // Next, pad out the unused tail of the last region with filler 284 // objects, for improved usage accounting. 285 // How many words we use for filler objects. 286 size_t word_fill_size = word_size_sum - word_size; 287 288 // How many words memory we "waste" which cannot hold a filler object. 289 size_t words_not_fillable = 0; 290 291 if (word_fill_size >= min_fill_size()) { 292 fill_with_objects(obj_top, word_fill_size); 293 } else if (word_fill_size > 0) { 294 // We have space to fill, but we cannot fit an object there. 295 words_not_fillable = word_fill_size; 296 word_fill_size = 0; 297 } 298 299 // We will set up the first region as "starts humongous". This 300 // will also update the BOT covering all the regions to reflect 301 // that there is a single object that starts at the bottom of the 302 // first region. 303 first_hr->set_starts_humongous(obj_top, word_fill_size); 304 // Then, if there are any, we will set up the "continues 305 // humongous" regions. 306 HeapRegion* hr = NULL; 307 for (uint i = first + 1; i <= last; ++i) { 308 hr = region_at(i); 309 hr->set_continues_humongous(first_hr); 310 } 311 312 // Up to this point no concurrent thread would have been able to 313 // do any scanning on any region in this series. All the top 314 // fields still point to bottom, so the intersection between 315 // [bottom,top] and [card_start,card_end] will be empty. Before we 316 // update the top fields, we'll do a storestore to make sure that 317 // no thread sees the update to top before the zeroing of the 318 // object header and the BOT initialization. 319 OrderAccess::storestore(); 320 321 // Now, we will update the top fields of the "continues humongous" 322 // regions except the last one. 323 for (uint i = first; i < last; ++i) { 324 hr = region_at(i); 325 hr->set_top(hr->end()); 326 } 327 328 hr = region_at(last); 329 // If we cannot fit a filler object, we must set top to the end 330 // of the humongous object, otherwise we cannot iterate the heap 331 // and the BOT will not be complete. 332 hr->set_top(hr->end() - words_not_fillable); 333 334 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 335 "obj_top should be in last region"); 336 337 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 338 339 assert(words_not_fillable == 0 || 340 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 341 "Miscalculation in humongous allocation"); 342 343 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 344 345 for (uint i = first; i <= last; ++i) { 346 hr = region_at(i); 347 _humongous_set.add(hr); 348 _hr_printer.alloc(hr); 349 } 350 351 return new_obj; 352 } 353 354 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 355 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 356 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 357 } 358 359 // If could fit into free regions w/o expansion, try. 360 // Otherwise, if can expand, do so. 361 // Otherwise, if using ex regions might help, try with ex given back. 362 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 363 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 364 365 _verifier->verify_region_sets_optional(); 366 367 uint first = G1_NO_HRM_INDEX; 368 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 369 370 if (obj_regions == 1) { 371 // Only one region to allocate, try to use a fast path by directly allocating 372 // from the free lists. Do not try to expand here, we will potentially do that 373 // later. 374 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 375 if (hr != NULL) { 376 first = hr->hrm_index(); 377 } 378 } else { 379 // We can't allocate humongous regions spanning more than one region while 380 // cleanupComplete() is running, since some of the regions we find to be 381 // empty might not yet be added to the free list. It is not straightforward 382 // to know in which list they are on so that we can remove them. We only 383 // need to do this if we need to allocate more than one region to satisfy the 384 // current humongous allocation request. If we are only allocating one region 385 // we use the one-region region allocation code (see above), that already 386 // potentially waits for regions from the secondary free list. 387 wait_while_free_regions_coming(); 388 append_secondary_free_list_if_not_empty_with_lock(); 389 390 // Policy: Try only empty regions (i.e. already committed first). Maybe we 391 // are lucky enough to find some. 392 first = _hrm.find_contiguous_only_empty(obj_regions); 393 if (first != G1_NO_HRM_INDEX) { 394 _hrm.allocate_free_regions_starting_at(first, obj_regions); 395 } 396 } 397 398 if (first == G1_NO_HRM_INDEX) { 399 // Policy: We could not find enough regions for the humongous object in the 400 // free list. Look through the heap to find a mix of free and uncommitted regions. 401 // If so, try expansion. 402 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 403 if (first != G1_NO_HRM_INDEX) { 404 // We found something. Make sure these regions are committed, i.e. expand 405 // the heap. Alternatively we could do a defragmentation GC. 406 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", 407 word_size * HeapWordSize); 408 409 _hrm.expand_at(first, obj_regions, workers()); 410 g1_policy()->record_new_heap_size(num_regions()); 411 412 #ifdef ASSERT 413 for (uint i = first; i < first + obj_regions; ++i) { 414 HeapRegion* hr = region_at(i); 415 assert(hr->is_free(), "sanity"); 416 assert(hr->is_empty(), "sanity"); 417 assert(is_on_master_free_list(hr), "sanity"); 418 } 419 #endif 420 _hrm.allocate_free_regions_starting_at(first, obj_regions); 421 } else { 422 // Policy: Potentially trigger a defragmentation GC. 423 } 424 } 425 426 HeapWord* result = NULL; 427 if (first != G1_NO_HRM_INDEX) { 428 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size); 429 assert(result != NULL, "it should always return a valid result"); 430 431 // A successful humongous object allocation changes the used space 432 // information of the old generation so we need to recalculate the 433 // sizes and update the jstat counters here. 434 g1mm()->update_sizes(); 435 } 436 437 _verifier->verify_region_sets_optional(); 438 439 return result; 440 } 441 442 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 443 assert_heap_not_locked_and_not_at_safepoint(); 444 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 445 446 return attempt_allocation(word_size); 447 } 448 449 HeapWord* 450 G1CollectedHeap::mem_allocate(size_t word_size, 451 bool* gc_overhead_limit_was_exceeded) { 452 assert_heap_not_locked_and_not_at_safepoint(); 453 454 if (is_humongous(word_size)) { 455 return attempt_allocation_humongous(word_size); 456 } 457 return attempt_allocation(word_size); 458 } 459 460 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 461 ResourceMark rm; // For retrieving the thread names in log messages. 462 463 // Make sure you read the note in attempt_allocation_humongous(). 464 465 assert_heap_not_locked_and_not_at_safepoint(); 466 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 467 "be called for humongous allocation requests"); 468 469 // We should only get here after the first-level allocation attempt 470 // (attempt_allocation()) failed to allocate. 471 472 // We will loop until a) we manage to successfully perform the 473 // allocation or b) we successfully schedule a collection which 474 // fails to perform the allocation. b) is the only case when we'll 475 // return NULL. 476 HeapWord* result = NULL; 477 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 478 bool should_try_gc; 479 uint gc_count_before; 480 481 { 482 MutexLockerEx x(Heap_lock); 483 result = _allocator->attempt_allocation_locked(word_size); 484 if (result != NULL) { 485 return result; 486 } 487 488 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 489 // This is different to when only GCLocker::needs_gc() is set: try to avoid 490 // waiting because the GCLocker is active to not wait too long. 491 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) { 492 // No need for an ergo message here, can_expand_young_list() does this when 493 // it returns true. 494 result = _allocator->attempt_allocation_force(word_size); 495 if (result != NULL) { 496 return result; 497 } 498 } 499 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 500 // the GCLocker initiated GC has been performed and then retry. This includes 501 // the case when the GC Locker is not active but has not been performed. 502 should_try_gc = !GCLocker::needs_gc(); 503 // Read the GC count while still holding the Heap_lock. 504 gc_count_before = total_collections(); 505 } 506 507 if (should_try_gc) { 508 bool succeeded; 509 result = do_collection_pause(word_size, gc_count_before, &succeeded, 510 GCCause::_g1_inc_collection_pause); 511 if (result != NULL) { 512 assert(succeeded, "only way to get back a non-NULL result"); 513 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 514 Thread::current()->name(), p2i(result)); 515 return result; 516 } 517 518 if (succeeded) { 519 // We successfully scheduled a collection which failed to allocate. No 520 // point in trying to allocate further. We'll just return NULL. 521 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 522 SIZE_FORMAT " words", Thread::current()->name(), word_size); 523 return NULL; 524 } 525 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 526 Thread::current()->name(), word_size); 527 } else { 528 // Failed to schedule a collection. 529 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 530 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 531 SIZE_FORMAT " words", Thread::current()->name(), word_size); 532 return NULL; 533 } 534 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 535 // The GCLocker is either active or the GCLocker initiated 536 // GC has not yet been performed. Stall until it is and 537 // then retry the allocation. 538 GCLocker::stall_until_clear(); 539 gclocker_retry_count += 1; 540 } 541 542 // We can reach here if we were unsuccessful in scheduling a 543 // collection (because another thread beat us to it) or if we were 544 // stalled due to the GC locker. In either can we should retry the 545 // allocation attempt in case another thread successfully 546 // performed a collection and reclaimed enough space. We do the 547 // first attempt (without holding the Heap_lock) here and the 548 // follow-on attempt will be at the start of the next loop 549 // iteration (after taking the Heap_lock). 550 551 result = _allocator->attempt_allocation(word_size); 552 if (result != NULL) { 553 return result; 554 } 555 556 // Give a warning if we seem to be looping forever. 557 if ((QueuedAllocationWarningCount > 0) && 558 (try_count % QueuedAllocationWarningCount == 0)) { 559 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 560 Thread::current()->name(), try_count, word_size); 561 } 562 } 563 564 ShouldNotReachHere(); 565 return NULL; 566 } 567 568 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 569 assert_at_safepoint_on_vm_thread(); 570 if (_archive_allocator == NULL) { 571 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 572 } 573 } 574 575 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 576 // Allocations in archive regions cannot be of a size that would be considered 577 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 578 // may be different at archive-restore time. 579 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 580 } 581 582 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 583 assert_at_safepoint_on_vm_thread(); 584 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 585 if (is_archive_alloc_too_large(word_size)) { 586 return NULL; 587 } 588 return _archive_allocator->archive_mem_allocate(word_size); 589 } 590 591 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 592 size_t end_alignment_in_bytes) { 593 assert_at_safepoint_on_vm_thread(); 594 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 595 596 // Call complete_archive to do the real work, filling in the MemRegion 597 // array with the archive regions. 598 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 599 delete _archive_allocator; 600 _archive_allocator = NULL; 601 } 602 603 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 604 assert(ranges != NULL, "MemRegion array NULL"); 605 assert(count != 0, "No MemRegions provided"); 606 MemRegion reserved = _hrm.reserved(); 607 for (size_t i = 0; i < count; i++) { 608 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 609 return false; 610 } 611 } 612 return true; 613 } 614 615 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 616 size_t count, 617 bool open) { 618 assert(!is_init_completed(), "Expect to be called at JVM init time"); 619 assert(ranges != NULL, "MemRegion array NULL"); 620 assert(count != 0, "No MemRegions provided"); 621 MutexLockerEx x(Heap_lock); 622 623 MemRegion reserved = _hrm.reserved(); 624 HeapWord* prev_last_addr = NULL; 625 HeapRegion* prev_last_region = NULL; 626 627 // Temporarily disable pretouching of heap pages. This interface is used 628 // when mmap'ing archived heap data in, so pre-touching is wasted. 629 FlagSetting fs(AlwaysPreTouch, false); 630 631 // Enable archive object checking used by G1MarkSweep. We have to let it know 632 // about each archive range, so that objects in those ranges aren't marked. 633 G1ArchiveAllocator::enable_archive_object_check(); 634 635 // For each specified MemRegion range, allocate the corresponding G1 636 // regions and mark them as archive regions. We expect the ranges 637 // in ascending starting address order, without overlap. 638 for (size_t i = 0; i < count; i++) { 639 MemRegion curr_range = ranges[i]; 640 HeapWord* start_address = curr_range.start(); 641 size_t word_size = curr_range.word_size(); 642 HeapWord* last_address = curr_range.last(); 643 size_t commits = 0; 644 645 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 646 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 647 p2i(start_address), p2i(last_address)); 648 guarantee(start_address > prev_last_addr, 649 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 650 p2i(start_address), p2i(prev_last_addr)); 651 prev_last_addr = last_address; 652 653 // Check for ranges that start in the same G1 region in which the previous 654 // range ended, and adjust the start address so we don't try to allocate 655 // the same region again. If the current range is entirely within that 656 // region, skip it, just adjusting the recorded top. 657 HeapRegion* start_region = _hrm.addr_to_region(start_address); 658 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 659 start_address = start_region->end(); 660 if (start_address > last_address) { 661 increase_used(word_size * HeapWordSize); 662 start_region->set_top(last_address + 1); 663 continue; 664 } 665 start_region->set_top(start_address); 666 curr_range = MemRegion(start_address, last_address + 1); 667 start_region = _hrm.addr_to_region(start_address); 668 } 669 670 // Perform the actual region allocation, exiting if it fails. 671 // Then note how much new space we have allocated. 672 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) { 673 return false; 674 } 675 increase_used(word_size * HeapWordSize); 676 if (commits != 0) { 677 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 678 HeapRegion::GrainWords * HeapWordSize * commits); 679 680 } 681 682 // Mark each G1 region touched by the range as archive, add it to 683 // the old set, and set top. 684 HeapRegion* curr_region = _hrm.addr_to_region(start_address); 685 HeapRegion* last_region = _hrm.addr_to_region(last_address); 686 prev_last_region = last_region; 687 688 while (curr_region != NULL) { 689 assert(curr_region->is_empty() && !curr_region->is_pinned(), 690 "Region already in use (index %u)", curr_region->hrm_index()); 691 if (open) { 692 curr_region->set_open_archive(); 693 } else { 694 curr_region->set_closed_archive(); 695 } 696 _hr_printer.alloc(curr_region); 697 _old_set.add(curr_region); 698 HeapWord* top; 699 HeapRegion* next_region; 700 if (curr_region != last_region) { 701 top = curr_region->end(); 702 next_region = _hrm.next_region_in_heap(curr_region); 703 } else { 704 top = last_address + 1; 705 next_region = NULL; 706 } 707 curr_region->set_top(top); 708 curr_region->set_first_dead(top); 709 curr_region->set_end_of_live(top); 710 curr_region = next_region; 711 } 712 713 // Notify mark-sweep of the archive 714 G1ArchiveAllocator::set_range_archive(curr_range, open); 715 } 716 return true; 717 } 718 719 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 720 assert(!is_init_completed(), "Expect to be called at JVM init time"); 721 assert(ranges != NULL, "MemRegion array NULL"); 722 assert(count != 0, "No MemRegions provided"); 723 MemRegion reserved = _hrm.reserved(); 724 HeapWord *prev_last_addr = NULL; 725 HeapRegion* prev_last_region = NULL; 726 727 // For each MemRegion, create filler objects, if needed, in the G1 regions 728 // that contain the address range. The address range actually within the 729 // MemRegion will not be modified. That is assumed to have been initialized 730 // elsewhere, probably via an mmap of archived heap data. 731 MutexLockerEx x(Heap_lock); 732 for (size_t i = 0; i < count; i++) { 733 HeapWord* start_address = ranges[i].start(); 734 HeapWord* last_address = ranges[i].last(); 735 736 assert(reserved.contains(start_address) && reserved.contains(last_address), 737 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 738 p2i(start_address), p2i(last_address)); 739 assert(start_address > prev_last_addr, 740 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 741 p2i(start_address), p2i(prev_last_addr)); 742 743 HeapRegion* start_region = _hrm.addr_to_region(start_address); 744 HeapRegion* last_region = _hrm.addr_to_region(last_address); 745 HeapWord* bottom_address = start_region->bottom(); 746 747 // Check for a range beginning in the same region in which the 748 // previous one ended. 749 if (start_region == prev_last_region) { 750 bottom_address = prev_last_addr + 1; 751 } 752 753 // Verify that the regions were all marked as archive regions by 754 // alloc_archive_regions. 755 HeapRegion* curr_region = start_region; 756 while (curr_region != NULL) { 757 guarantee(curr_region->is_archive(), 758 "Expected archive region at index %u", curr_region->hrm_index()); 759 if (curr_region != last_region) { 760 curr_region = _hrm.next_region_in_heap(curr_region); 761 } else { 762 curr_region = NULL; 763 } 764 } 765 766 prev_last_addr = last_address; 767 prev_last_region = last_region; 768 769 // Fill the memory below the allocated range with dummy object(s), 770 // if the region bottom does not match the range start, or if the previous 771 // range ended within the same G1 region, and there is a gap. 772 if (start_address != bottom_address) { 773 size_t fill_size = pointer_delta(start_address, bottom_address); 774 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 775 increase_used(fill_size * HeapWordSize); 776 } 777 } 778 } 779 780 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size) { 781 assert_heap_not_locked_and_not_at_safepoint(); 782 assert(!is_humongous(word_size), "attempt_allocation() should not " 783 "be called for humongous allocation requests"); 784 785 HeapWord* result = _allocator->attempt_allocation(word_size); 786 787 if (result == NULL) { 788 result = attempt_allocation_slow(word_size); 789 } 790 assert_heap_not_locked(); 791 if (result != NULL) { 792 dirty_young_block(result, word_size); 793 } 794 return result; 795 } 796 797 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 798 assert(!is_init_completed(), "Expect to be called at JVM init time"); 799 assert(ranges != NULL, "MemRegion array NULL"); 800 assert(count != 0, "No MemRegions provided"); 801 MemRegion reserved = _hrm.reserved(); 802 HeapWord* prev_last_addr = NULL; 803 HeapRegion* prev_last_region = NULL; 804 size_t size_used = 0; 805 size_t uncommitted_regions = 0; 806 807 // For each Memregion, free the G1 regions that constitute it, and 808 // notify mark-sweep that the range is no longer to be considered 'archive.' 809 MutexLockerEx x(Heap_lock); 810 for (size_t i = 0; i < count; i++) { 811 HeapWord* start_address = ranges[i].start(); 812 HeapWord* last_address = ranges[i].last(); 813 814 assert(reserved.contains(start_address) && reserved.contains(last_address), 815 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 816 p2i(start_address), p2i(last_address)); 817 assert(start_address > prev_last_addr, 818 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 819 p2i(start_address), p2i(prev_last_addr)); 820 size_used += ranges[i].byte_size(); 821 prev_last_addr = last_address; 822 823 HeapRegion* start_region = _hrm.addr_to_region(start_address); 824 HeapRegion* last_region = _hrm.addr_to_region(last_address); 825 826 // Check for ranges that start in the same G1 region in which the previous 827 // range ended, and adjust the start address so we don't try to free 828 // the same region again. If the current range is entirely within that 829 // region, skip it. 830 if (start_region == prev_last_region) { 831 start_address = start_region->end(); 832 if (start_address > last_address) { 833 continue; 834 } 835 start_region = _hrm.addr_to_region(start_address); 836 } 837 prev_last_region = last_region; 838 839 // After verifying that each region was marked as an archive region by 840 // alloc_archive_regions, set it free and empty and uncommit it. 841 HeapRegion* curr_region = start_region; 842 while (curr_region != NULL) { 843 guarantee(curr_region->is_archive(), 844 "Expected archive region at index %u", curr_region->hrm_index()); 845 uint curr_index = curr_region->hrm_index(); 846 _old_set.remove(curr_region); 847 curr_region->set_free(); 848 curr_region->set_top(curr_region->bottom()); 849 if (curr_region != last_region) { 850 curr_region = _hrm.next_region_in_heap(curr_region); 851 } else { 852 curr_region = NULL; 853 } 854 _hrm.shrink_at(curr_index, 1); 855 uncommitted_regions++; 856 } 857 858 // Notify mark-sweep that this is no longer an archive range. 859 G1ArchiveAllocator::set_range_archive(ranges[i], false); 860 } 861 862 if (uncommitted_regions != 0) { 863 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 864 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 865 } 866 decrease_used(size_used); 867 } 868 869 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 870 ResourceMark rm; // For retrieving the thread names in log messages. 871 872 // The structure of this method has a lot of similarities to 873 // attempt_allocation_slow(). The reason these two were not merged 874 // into a single one is that such a method would require several "if 875 // allocation is not humongous do this, otherwise do that" 876 // conditional paths which would obscure its flow. In fact, an early 877 // version of this code did use a unified method which was harder to 878 // follow and, as a result, it had subtle bugs that were hard to 879 // track down. So keeping these two methods separate allows each to 880 // be more readable. It will be good to keep these two in sync as 881 // much as possible. 882 883 assert_heap_not_locked_and_not_at_safepoint(); 884 assert(is_humongous(word_size), "attempt_allocation_humongous() " 885 "should only be called for humongous allocations"); 886 887 // Humongous objects can exhaust the heap quickly, so we should check if we 888 // need to start a marking cycle at each humongous object allocation. We do 889 // the check before we do the actual allocation. The reason for doing it 890 // before the allocation is that we avoid having to keep track of the newly 891 // allocated memory while we do a GC. 892 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 893 word_size)) { 894 collect(GCCause::_g1_humongous_allocation); 895 } 896 897 // We will loop until a) we manage to successfully perform the 898 // allocation or b) we successfully schedule a collection which 899 // fails to perform the allocation. b) is the only case when we'll 900 // return NULL. 901 HeapWord* result = NULL; 902 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 903 bool should_try_gc; 904 uint gc_count_before; 905 906 907 { 908 MutexLockerEx x(Heap_lock); 909 910 // Given that humongous objects are not allocated in young 911 // regions, we'll first try to do the allocation without doing a 912 // collection hoping that there's enough space in the heap. 913 result = humongous_obj_allocate(word_size); 914 if (result != NULL) { 915 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 916 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 917 return result; 918 } 919 920 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 921 // the GCLocker initiated GC has been performed and then retry. This includes 922 // the case when the GC Locker is not active but has not been performed. 923 should_try_gc = !GCLocker::needs_gc(); 924 // Read the GC count while still holding the Heap_lock. 925 gc_count_before = total_collections(); 926 } 927 928 if (should_try_gc) { 929 bool succeeded; 930 result = do_collection_pause(word_size, gc_count_before, &succeeded, 931 GCCause::_g1_humongous_allocation); 932 if (result != NULL) { 933 assert(succeeded, "only way to get back a non-NULL result"); 934 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 935 Thread::current()->name(), p2i(result)); 936 return result; 937 } 938 939 if (succeeded) { 940 // We successfully scheduled a collection which failed to allocate. No 941 // point in trying to allocate further. We'll just return NULL. 942 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 943 SIZE_FORMAT " words", Thread::current()->name(), word_size); 944 return NULL; 945 } 946 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 947 Thread::current()->name(), word_size); 948 } else { 949 // Failed to schedule a collection. 950 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 951 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 952 SIZE_FORMAT " words", Thread::current()->name(), word_size); 953 return NULL; 954 } 955 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 956 // The GCLocker is either active or the GCLocker initiated 957 // GC has not yet been performed. Stall until it is and 958 // then retry the allocation. 959 GCLocker::stall_until_clear(); 960 gclocker_retry_count += 1; 961 } 962 963 964 // We can reach here if we were unsuccessful in scheduling a 965 // collection (because another thread beat us to it) or if we were 966 // stalled due to the GC locker. In either can we should retry the 967 // allocation attempt in case another thread successfully 968 // performed a collection and reclaimed enough space. 969 // Humongous object allocation always needs a lock, so we wait for the retry 970 // in the next iteration of the loop, unlike for the regular iteration case. 971 // Give a warning if we seem to be looping forever. 972 973 if ((QueuedAllocationWarningCount > 0) && 974 (try_count % QueuedAllocationWarningCount == 0)) { 975 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 976 Thread::current()->name(), try_count, word_size); 977 } 978 } 979 980 ShouldNotReachHere(); 981 return NULL; 982 } 983 984 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 985 bool expect_null_mutator_alloc_region) { 986 assert_at_safepoint_on_vm_thread(); 987 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 988 "the current alloc region was unexpectedly found to be non-NULL"); 989 990 if (!is_humongous(word_size)) { 991 return _allocator->attempt_allocation_locked(word_size); 992 } else { 993 HeapWord* result = humongous_obj_allocate(word_size); 994 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 995 collector_state()->set_initiate_conc_mark_if_possible(true); 996 } 997 return result; 998 } 999 1000 ShouldNotReachHere(); 1001 } 1002 1003 class PostCompactionPrinterClosure: public HeapRegionClosure { 1004 private: 1005 G1HRPrinter* _hr_printer; 1006 public: 1007 bool do_heap_region(HeapRegion* hr) { 1008 assert(!hr->is_young(), "not expecting to find young regions"); 1009 _hr_printer->post_compaction(hr); 1010 return false; 1011 } 1012 1013 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1014 : _hr_printer(hr_printer) { } 1015 }; 1016 1017 void G1CollectedHeap::print_hrm_post_compaction() { 1018 if (_hr_printer.is_active()) { 1019 PostCompactionPrinterClosure cl(hr_printer()); 1020 heap_region_iterate(&cl); 1021 } 1022 } 1023 1024 void G1CollectedHeap::abort_concurrent_cycle() { 1025 // Note: When we have a more flexible GC logging framework that 1026 // allows us to add optional attributes to a GC log record we 1027 // could consider timing and reporting how long we wait in the 1028 // following two methods. 1029 wait_while_free_regions_coming(); 1030 // If we start the compaction before the CM threads finish 1031 // scanning the root regions we might trip them over as we'll 1032 // be moving objects / updating references. So let's wait until 1033 // they are done. By telling them to abort, they should complete 1034 // early. 1035 _cm->root_regions()->abort(); 1036 _cm->root_regions()->wait_until_scan_finished(); 1037 append_secondary_free_list_if_not_empty_with_lock(); 1038 1039 // Disable discovery and empty the discovered lists 1040 // for the CM ref processor. 1041 ref_processor_cm()->disable_discovery(); 1042 ref_processor_cm()->abandon_partial_discovery(); 1043 ref_processor_cm()->verify_no_references_recorded(); 1044 1045 // Abandon current iterations of concurrent marking and concurrent 1046 // refinement, if any are in progress. 1047 concurrent_mark()->abort(); 1048 } 1049 1050 void G1CollectedHeap::prepare_heap_for_full_collection() { 1051 // Make sure we'll choose a new allocation region afterwards. 1052 _allocator->release_mutator_alloc_region(); 1053 _allocator->abandon_gc_alloc_regions(); 1054 g1_rem_set()->cleanupHRRS(); 1055 1056 // We may have added regions to the current incremental collection 1057 // set between the last GC or pause and now. We need to clear the 1058 // incremental collection set and then start rebuilding it afresh 1059 // after this full GC. 1060 abandon_collection_set(collection_set()); 1061 1062 tear_down_region_sets(false /* free_list_only */); 1063 collector_state()->set_gcs_are_young(true); 1064 } 1065 1066 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1067 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1068 assert(used() == recalculate_used(), "Should be equal"); 1069 _verifier->verify_region_sets_optional(); 1070 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1071 _verifier->check_bitmaps("Full GC Start"); 1072 } 1073 1074 void G1CollectedHeap::prepare_heap_for_mutators() { 1075 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1076 ClassLoaderDataGraph::purge(); 1077 MetaspaceAux::verify_metrics(); 1078 1079 // Prepare heap for normal collections. 1080 assert(num_free_regions() == 0, "we should not have added any free regions"); 1081 rebuild_region_sets(false /* free_list_only */); 1082 abort_refinement(); 1083 resize_if_necessary_after_full_collection(); 1084 1085 // Rebuild the strong code root lists for each region 1086 rebuild_strong_code_roots(); 1087 1088 // Start a new incremental collection set for the next pause 1089 start_new_collection_set(); 1090 1091 _allocator->init_mutator_alloc_region(); 1092 1093 // Post collection state updates. 1094 MetaspaceGC::compute_new_size(); 1095 } 1096 1097 void G1CollectedHeap::abort_refinement() { 1098 if (_hot_card_cache->use_cache()) { 1099 _hot_card_cache->reset_hot_cache(); 1100 } 1101 1102 // Discard all remembered set updates. 1103 JavaThread::dirty_card_queue_set().abandon_logs(); 1104 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1105 } 1106 1107 void G1CollectedHeap::verify_after_full_collection() { 1108 check_gc_time_stamps(); 1109 _hrm.verify_optional(); 1110 _verifier->verify_region_sets_optional(); 1111 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1112 // Clear the previous marking bitmap, if needed for bitmap verification. 1113 // Note we cannot do this when we clear the next marking bitmap in 1114 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1115 // objects marked during a full GC against the previous bitmap. 1116 // But we need to clear it before calling check_bitmaps below since 1117 // the full GC has compacted objects and updated TAMS but not updated 1118 // the prev bitmap. 1119 if (G1VerifyBitmaps) { 1120 GCTraceTime(Debug, gc)("Clear Bitmap for Verification"); 1121 _cm->clear_prev_bitmap(workers()); 1122 } 1123 _verifier->check_bitmaps("Full GC End"); 1124 1125 // At this point there should be no regions in the 1126 // entire heap tagged as young. 1127 assert(check_young_list_empty(), "young list should be empty at this point"); 1128 1129 // Note: since we've just done a full GC, concurrent 1130 // marking is no longer active. Therefore we need not 1131 // re-enable reference discovery for the CM ref processor. 1132 // That will be done at the start of the next marking cycle. 1133 // We also know that the STW processor should no longer 1134 // discover any new references. 1135 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1136 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1137 ref_processor_stw()->verify_no_references_recorded(); 1138 ref_processor_cm()->verify_no_references_recorded(); 1139 } 1140 1141 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1142 // Post collection logging. 1143 // We should do this after we potentially resize the heap so 1144 // that all the COMMIT / UNCOMMIT events are generated before 1145 // the compaction events. 1146 print_hrm_post_compaction(); 1147 heap_transition->print(); 1148 print_heap_after_gc(); 1149 print_heap_regions(); 1150 #ifdef TRACESPINNING 1151 ParallelTaskTerminator::print_termination_counts(); 1152 #endif 1153 } 1154 1155 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1156 bool clear_all_soft_refs) { 1157 assert_at_safepoint_on_vm_thread(); 1158 1159 if (GCLocker::check_active_before_gc()) { 1160 // Full GC was not completed. 1161 return false; 1162 } 1163 1164 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1165 soft_ref_policy()->should_clear_all_soft_refs(); 1166 1167 G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs); 1168 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1169 1170 collector.prepare_collection(); 1171 collector.collect(); 1172 collector.complete_collection(); 1173 1174 // Full collection was successfully completed. 1175 return true; 1176 } 1177 1178 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1179 // Currently, there is no facility in the do_full_collection(bool) API to notify 1180 // the caller that the collection did not succeed (e.g., because it was locked 1181 // out by the GC locker). So, right now, we'll ignore the return value. 1182 bool dummy = do_full_collection(true, /* explicit_gc */ 1183 clear_all_soft_refs); 1184 } 1185 1186 void G1CollectedHeap::resize_if_necessary_after_full_collection() { 1187 // Capacity, free and used after the GC counted as full regions to 1188 // include the waste in the following calculations. 1189 const size_t capacity_after_gc = capacity(); 1190 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1191 1192 // This is enforced in arguments.cpp. 1193 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1194 "otherwise the code below doesn't make sense"); 1195 1196 // We don't have floating point command-line arguments 1197 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1198 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1199 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1200 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1201 1202 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1203 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1204 1205 // We have to be careful here as these two calculations can overflow 1206 // 32-bit size_t's. 1207 double used_after_gc_d = (double) used_after_gc; 1208 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1209 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1210 1211 // Let's make sure that they are both under the max heap size, which 1212 // by default will make them fit into a size_t. 1213 double desired_capacity_upper_bound = (double) max_heap_size; 1214 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1215 desired_capacity_upper_bound); 1216 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1217 desired_capacity_upper_bound); 1218 1219 // We can now safely turn them into size_t's. 1220 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1221 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1222 1223 // This assert only makes sense here, before we adjust them 1224 // with respect to the min and max heap size. 1225 assert(minimum_desired_capacity <= maximum_desired_capacity, 1226 "minimum_desired_capacity = " SIZE_FORMAT ", " 1227 "maximum_desired_capacity = " SIZE_FORMAT, 1228 minimum_desired_capacity, maximum_desired_capacity); 1229 1230 // Should not be greater than the heap max size. No need to adjust 1231 // it with respect to the heap min size as it's a lower bound (i.e., 1232 // we'll try to make the capacity larger than it, not smaller). 1233 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1234 // Should not be less than the heap min size. No need to adjust it 1235 // with respect to the heap max size as it's an upper bound (i.e., 1236 // we'll try to make the capacity smaller than it, not greater). 1237 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1238 1239 if (capacity_after_gc < minimum_desired_capacity) { 1240 // Don't expand unless it's significant 1241 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1242 1243 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). " 1244 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1245 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1246 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1247 1248 expand(expand_bytes, _workers); 1249 1250 // No expansion, now see if we want to shrink 1251 } else if (capacity_after_gc > maximum_desired_capacity) { 1252 // Capacity too large, compute shrinking size 1253 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1254 1255 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). " 1256 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1257 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1258 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1259 1260 shrink(shrink_bytes); 1261 } 1262 } 1263 1264 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1265 bool do_gc, 1266 bool clear_all_soft_refs, 1267 bool expect_null_mutator_alloc_region, 1268 bool* gc_succeeded) { 1269 *gc_succeeded = true; 1270 // Let's attempt the allocation first. 1271 HeapWord* result = 1272 attempt_allocation_at_safepoint(word_size, 1273 expect_null_mutator_alloc_region); 1274 if (result != NULL) { 1275 return result; 1276 } 1277 1278 // In a G1 heap, we're supposed to keep allocation from failing by 1279 // incremental pauses. Therefore, at least for now, we'll favor 1280 // expansion over collection. (This might change in the future if we can 1281 // do something smarter than full collection to satisfy a failed alloc.) 1282 result = expand_and_allocate(word_size); 1283 if (result != NULL) { 1284 return result; 1285 } 1286 1287 if (do_gc) { 1288 // Expansion didn't work, we'll try to do a Full GC. 1289 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1290 clear_all_soft_refs); 1291 } 1292 1293 return NULL; 1294 } 1295 1296 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1297 bool* succeeded) { 1298 assert_at_safepoint_on_vm_thread(); 1299 1300 // Attempts to allocate followed by Full GC. 1301 HeapWord* result = 1302 satisfy_failed_allocation_helper(word_size, 1303 true, /* do_gc */ 1304 false, /* clear_all_soft_refs */ 1305 false, /* expect_null_mutator_alloc_region */ 1306 succeeded); 1307 1308 if (result != NULL || !*succeeded) { 1309 return result; 1310 } 1311 1312 // Attempts to allocate followed by Full GC that will collect all soft references. 1313 result = satisfy_failed_allocation_helper(word_size, 1314 true, /* do_gc */ 1315 true, /* clear_all_soft_refs */ 1316 true, /* expect_null_mutator_alloc_region */ 1317 succeeded); 1318 1319 if (result != NULL || !*succeeded) { 1320 return result; 1321 } 1322 1323 // Attempts to allocate, no GC 1324 result = satisfy_failed_allocation_helper(word_size, 1325 false, /* do_gc */ 1326 false, /* clear_all_soft_refs */ 1327 true, /* expect_null_mutator_alloc_region */ 1328 succeeded); 1329 1330 if (result != NULL) { 1331 return result; 1332 } 1333 1334 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1335 "Flag should have been handled and cleared prior to this point"); 1336 1337 // What else? We might try synchronous finalization later. If the total 1338 // space available is large enough for the allocation, then a more 1339 // complete compaction phase than we've tried so far might be 1340 // appropriate. 1341 return NULL; 1342 } 1343 1344 // Attempting to expand the heap sufficiently 1345 // to support an allocation of the given "word_size". If 1346 // successful, perform the allocation and return the address of the 1347 // allocated block, or else "NULL". 1348 1349 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1350 assert_at_safepoint_on_vm_thread(); 1351 1352 _verifier->verify_region_sets_optional(); 1353 1354 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1355 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1356 word_size * HeapWordSize); 1357 1358 1359 if (expand(expand_bytes, _workers)) { 1360 _hrm.verify_optional(); 1361 _verifier->verify_region_sets_optional(); 1362 return attempt_allocation_at_safepoint(word_size, 1363 false /* expect_null_mutator_alloc_region */); 1364 } 1365 return NULL; 1366 } 1367 1368 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1369 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1370 aligned_expand_bytes = align_up(aligned_expand_bytes, 1371 HeapRegion::GrainBytes); 1372 1373 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1374 expand_bytes, aligned_expand_bytes); 1375 1376 if (is_maximal_no_gc()) { 1377 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1378 return false; 1379 } 1380 1381 double expand_heap_start_time_sec = os::elapsedTime(); 1382 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1383 assert(regions_to_expand > 0, "Must expand by at least one region"); 1384 1385 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers); 1386 if (expand_time_ms != NULL) { 1387 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1388 } 1389 1390 if (expanded_by > 0) { 1391 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1392 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1393 g1_policy()->record_new_heap_size(num_regions()); 1394 } else { 1395 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1396 1397 // The expansion of the virtual storage space was unsuccessful. 1398 // Let's see if it was because we ran out of swap. 1399 if (G1ExitOnExpansionFailure && 1400 _hrm.available() >= regions_to_expand) { 1401 // We had head room... 1402 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1403 } 1404 } 1405 return regions_to_expand > 0; 1406 } 1407 1408 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1409 size_t aligned_shrink_bytes = 1410 ReservedSpace::page_align_size_down(shrink_bytes); 1411 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1412 HeapRegion::GrainBytes); 1413 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1414 1415 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1416 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1417 1418 1419 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", 1420 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1421 if (num_regions_removed > 0) { 1422 g1_policy()->record_new_heap_size(num_regions()); 1423 } else { 1424 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1425 } 1426 } 1427 1428 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1429 _verifier->verify_region_sets_optional(); 1430 1431 // We should only reach here at the end of a Full GC which means we 1432 // should not not be holding to any GC alloc regions. The method 1433 // below will make sure of that and do any remaining clean up. 1434 _allocator->abandon_gc_alloc_regions(); 1435 1436 // Instead of tearing down / rebuilding the free lists here, we 1437 // could instead use the remove_all_pending() method on free_list to 1438 // remove only the ones that we need to remove. 1439 tear_down_region_sets(true /* free_list_only */); 1440 shrink_helper(shrink_bytes); 1441 rebuild_region_sets(true /* free_list_only */); 1442 1443 _hrm.verify_optional(); 1444 _verifier->verify_region_sets_optional(); 1445 } 1446 1447 // Public methods. 1448 1449 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) : 1450 CollectedHeap(), 1451 _young_gen_sampling_thread(NULL), 1452 _collector_policy(collector_policy), 1453 _soft_ref_policy(), 1454 _card_table(NULL), 1455 _memory_manager("G1 Young Generation", "end of minor GC"), 1456 _full_gc_memory_manager("G1 Old Generation", "end of major GC"), 1457 _eden_pool(NULL), 1458 _survivor_pool(NULL), 1459 _old_pool(NULL), 1460 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1461 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1462 _g1_policy(new G1DefaultPolicy(_gc_timer_stw)), 1463 _collection_set(this, _g1_policy), 1464 _dirty_card_queue_set(false), 1465 _is_alive_closure_cm(this), 1466 _is_alive_closure_stw(this), 1467 _ref_processor_cm(NULL), 1468 _ref_processor_stw(NULL), 1469 _bot(NULL), 1470 _hot_card_cache(NULL), 1471 _g1_rem_set(NULL), 1472 _cr(NULL), 1473 _g1mm(NULL), 1474 _preserved_marks_set(true /* in_c_heap */), 1475 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1476 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1477 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1478 _humongous_reclaim_candidates(), 1479 _has_humongous_reclaim_candidates(false), 1480 _archive_allocator(NULL), 1481 _free_regions_coming(false), 1482 _gc_time_stamp(0), 1483 _summary_bytes_used(0), 1484 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1485 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1486 _expand_heap_after_alloc_failure(true), 1487 _old_marking_cycles_started(0), 1488 _old_marking_cycles_completed(0), 1489 _in_cset_fast_test() { 1490 1491 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1492 /* are_GC_task_threads */true, 1493 /* are_ConcurrentGC_threads */false); 1494 _workers->initialize_workers(); 1495 _verifier = new G1HeapVerifier(this); 1496 1497 _allocator = new G1DefaultAllocator(this); 1498 1499 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics()); 1500 1501 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1502 1503 // Override the default _filler_array_max_size so that no humongous filler 1504 // objects are created. 1505 _filler_array_max_size = _humongous_object_threshold_in_words; 1506 1507 uint n_queues = ParallelGCThreads; 1508 _task_queues = new RefToScanQueueSet(n_queues); 1509 1510 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1511 1512 for (uint i = 0; i < n_queues; i++) { 1513 RefToScanQueue* q = new RefToScanQueue(); 1514 q->initialize(); 1515 _task_queues->register_queue(i, q); 1516 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1517 } 1518 1519 // Initialize the G1EvacuationFailureALot counters and flags. 1520 NOT_PRODUCT(reset_evacuation_should_fail();) 1521 1522 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1523 } 1524 1525 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1526 size_t size, 1527 size_t translation_factor) { 1528 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1529 // Allocate a new reserved space, preferring to use large pages. 1530 ReservedSpace rs(size, preferred_page_size); 1531 G1RegionToSpaceMapper* result = 1532 G1RegionToSpaceMapper::create_mapper(rs, 1533 size, 1534 rs.alignment(), 1535 HeapRegion::GrainBytes, 1536 translation_factor, 1537 mtGC); 1538 1539 os::trace_page_sizes_for_requested_size(description, 1540 size, 1541 preferred_page_size, 1542 rs.alignment(), 1543 rs.base(), 1544 rs.size()); 1545 1546 return result; 1547 } 1548 1549 jint G1CollectedHeap::initialize_concurrent_refinement() { 1550 jint ecode = JNI_OK; 1551 _cr = G1ConcurrentRefine::create(&ecode); 1552 return ecode; 1553 } 1554 1555 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1556 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1557 if (_young_gen_sampling_thread->osthread() == NULL) { 1558 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1559 return JNI_ENOMEM; 1560 } 1561 return JNI_OK; 1562 } 1563 1564 jint G1CollectedHeap::initialize() { 1565 os::enable_vtime(); 1566 1567 // Necessary to satisfy locking discipline assertions. 1568 1569 MutexLocker x(Heap_lock); 1570 1571 // While there are no constraints in the GC code that HeapWordSize 1572 // be any particular value, there are multiple other areas in the 1573 // system which believe this to be true (e.g. oop->object_size in some 1574 // cases incorrectly returns the size in wordSize units rather than 1575 // HeapWordSize). 1576 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1577 1578 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1579 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1580 size_t heap_alignment = collector_policy()->heap_alignment(); 1581 1582 // Ensure that the sizes are properly aligned. 1583 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1584 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1585 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1586 1587 // Reserve the maximum. 1588 1589 // When compressed oops are enabled, the preferred heap base 1590 // is calculated by subtracting the requested size from the 1591 // 32Gb boundary and using the result as the base address for 1592 // heap reservation. If the requested size is not aligned to 1593 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1594 // into the ReservedHeapSpace constructor) then the actual 1595 // base of the reserved heap may end up differing from the 1596 // address that was requested (i.e. the preferred heap base). 1597 // If this happens then we could end up using a non-optimal 1598 // compressed oops mode. 1599 1600 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1601 heap_alignment); 1602 1603 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1604 1605 // Create the barrier set for the entire reserved region. 1606 G1CardTable* ct = new G1CardTable(reserved_region()); 1607 ct->initialize(); 1608 G1BarrierSet* bs = new G1BarrierSet(ct); 1609 bs->initialize(); 1610 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1611 set_barrier_set(bs); 1612 _card_table = ct; 1613 1614 // Create the hot card cache. 1615 _hot_card_cache = new G1HotCardCache(this); 1616 1617 // Carve out the G1 part of the heap. 1618 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1619 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 1620 G1RegionToSpaceMapper* heap_storage = 1621 G1RegionToSpaceMapper::create_mapper(g1_rs, 1622 g1_rs.size(), 1623 page_size, 1624 HeapRegion::GrainBytes, 1625 1, 1626 mtJavaHeap); 1627 os::trace_page_sizes("Heap", 1628 collector_policy()->min_heap_byte_size(), 1629 max_byte_size, 1630 page_size, 1631 heap_rs.base(), 1632 heap_rs.size()); 1633 heap_storage->set_mapping_changed_listener(&_listener); 1634 1635 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1636 G1RegionToSpaceMapper* bot_storage = 1637 create_aux_memory_mapper("Block Offset Table", 1638 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1639 G1BlockOffsetTable::heap_map_factor()); 1640 1641 G1RegionToSpaceMapper* cardtable_storage = 1642 create_aux_memory_mapper("Card Table", 1643 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1644 G1CardTable::heap_map_factor()); 1645 1646 G1RegionToSpaceMapper* card_counts_storage = 1647 create_aux_memory_mapper("Card Counts Table", 1648 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1649 G1CardCounts::heap_map_factor()); 1650 1651 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1652 G1RegionToSpaceMapper* prev_bitmap_storage = 1653 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1654 G1RegionToSpaceMapper* next_bitmap_storage = 1655 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1656 1657 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1658 _card_table->initialize(cardtable_storage); 1659 // Do later initialization work for concurrent refinement. 1660 _hot_card_cache->initialize(card_counts_storage); 1661 1662 // 6843694 - ensure that the maximum region index can fit 1663 // in the remembered set structures. 1664 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1665 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1666 1667 // Also create a G1 rem set. 1668 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1669 _g1_rem_set->initialize(max_capacity(), max_regions()); 1670 1671 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1672 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1673 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1674 "too many cards per region"); 1675 1676 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1677 1678 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1679 1680 { 1681 HeapWord* start = _hrm.reserved().start(); 1682 HeapWord* end = _hrm.reserved().end(); 1683 size_t granularity = HeapRegion::GrainBytes; 1684 1685 _in_cset_fast_test.initialize(start, end, granularity); 1686 _humongous_reclaim_candidates.initialize(start, end, granularity); 1687 } 1688 1689 // Create the G1ConcurrentMark data structure and thread. 1690 // (Must do this late, so that "max_regions" is defined.) 1691 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1692 if (_cm == NULL || !_cm->completed_initialization()) { 1693 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1694 return JNI_ENOMEM; 1695 } 1696 _cmThread = _cm->cm_thread(); 1697 1698 // Now expand into the initial heap size. 1699 if (!expand(init_byte_size, _workers)) { 1700 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1701 return JNI_ENOMEM; 1702 } 1703 1704 // Perform any initialization actions delegated to the policy. 1705 g1_policy()->init(this, &_collection_set); 1706 1707 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 1708 SATB_Q_FL_lock, 1709 G1SATBProcessCompletedThreshold, 1710 Shared_SATB_Q_lock); 1711 1712 jint ecode = initialize_concurrent_refinement(); 1713 if (ecode != JNI_OK) { 1714 return ecode; 1715 } 1716 1717 ecode = initialize_young_gen_sampling_thread(); 1718 if (ecode != JNI_OK) { 1719 return ecode; 1720 } 1721 1722 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1723 DirtyCardQ_FL_lock, 1724 (int)concurrent_refine()->yellow_zone(), 1725 (int)concurrent_refine()->red_zone(), 1726 Shared_DirtyCardQ_lock, 1727 NULL, // fl_owner 1728 true); // init_free_ids 1729 1730 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1731 DirtyCardQ_FL_lock, 1732 -1, // never trigger processing 1733 -1, // no limit on length 1734 Shared_DirtyCardQ_lock, 1735 &JavaThread::dirty_card_queue_set()); 1736 1737 // Here we allocate the dummy HeapRegion that is required by the 1738 // G1AllocRegion class. 1739 HeapRegion* dummy_region = _hrm.get_dummy_region(); 1740 1741 // We'll re-use the same region whether the alloc region will 1742 // require BOT updates or not and, if it doesn't, then a non-young 1743 // region will complain that it cannot support allocations without 1744 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1745 dummy_region->set_eden(); 1746 // Make sure it's full. 1747 dummy_region->set_top(dummy_region->end()); 1748 G1AllocRegion::setup(this, dummy_region); 1749 1750 _allocator->init_mutator_alloc_region(); 1751 1752 // Do create of the monitoring and management support so that 1753 // values in the heap have been properly initialized. 1754 _g1mm = new G1MonitoringSupport(this); 1755 1756 G1StringDedup::initialize(); 1757 1758 _preserved_marks_set.init(ParallelGCThreads); 1759 1760 _collection_set.initialize(max_regions()); 1761 1762 return JNI_OK; 1763 } 1764 1765 void G1CollectedHeap::initialize_serviceability() { 1766 _eden_pool = new G1EdenPool(this); 1767 _survivor_pool = new G1SurvivorPool(this); 1768 _old_pool = new G1OldGenPool(this); 1769 1770 _full_gc_memory_manager.add_pool(_eden_pool); 1771 _full_gc_memory_manager.add_pool(_survivor_pool); 1772 _full_gc_memory_manager.add_pool(_old_pool); 1773 1774 _memory_manager.add_pool(_eden_pool); 1775 _memory_manager.add_pool(_survivor_pool); 1776 1777 } 1778 1779 void G1CollectedHeap::stop() { 1780 // Stop all concurrent threads. We do this to make sure these threads 1781 // do not continue to execute and access resources (e.g. logging) 1782 // that are destroyed during shutdown. 1783 _cr->stop(); 1784 _young_gen_sampling_thread->stop(); 1785 _cmThread->stop(); 1786 if (G1StringDedup::is_enabled()) { 1787 G1StringDedup::stop(); 1788 } 1789 } 1790 1791 void G1CollectedHeap::safepoint_synchronize_begin() { 1792 SuspendibleThreadSet::synchronize(); 1793 } 1794 1795 void G1CollectedHeap::safepoint_synchronize_end() { 1796 SuspendibleThreadSet::desynchronize(); 1797 } 1798 1799 size_t G1CollectedHeap::conservative_max_heap_alignment() { 1800 return HeapRegion::max_region_size(); 1801 } 1802 1803 void G1CollectedHeap::post_initialize() { 1804 CollectedHeap::post_initialize(); 1805 ref_processing_init(); 1806 } 1807 1808 void G1CollectedHeap::ref_processing_init() { 1809 // Reference processing in G1 currently works as follows: 1810 // 1811 // * There are two reference processor instances. One is 1812 // used to record and process discovered references 1813 // during concurrent marking; the other is used to 1814 // record and process references during STW pauses 1815 // (both full and incremental). 1816 // * Both ref processors need to 'span' the entire heap as 1817 // the regions in the collection set may be dotted around. 1818 // 1819 // * For the concurrent marking ref processor: 1820 // * Reference discovery is enabled at initial marking. 1821 // * Reference discovery is disabled and the discovered 1822 // references processed etc during remarking. 1823 // * Reference discovery is MT (see below). 1824 // * Reference discovery requires a barrier (see below). 1825 // * Reference processing may or may not be MT 1826 // (depending on the value of ParallelRefProcEnabled 1827 // and ParallelGCThreads). 1828 // * A full GC disables reference discovery by the CM 1829 // ref processor and abandons any entries on it's 1830 // discovered lists. 1831 // 1832 // * For the STW processor: 1833 // * Non MT discovery is enabled at the start of a full GC. 1834 // * Processing and enqueueing during a full GC is non-MT. 1835 // * During a full GC, references are processed after marking. 1836 // 1837 // * Discovery (may or may not be MT) is enabled at the start 1838 // of an incremental evacuation pause. 1839 // * References are processed near the end of a STW evacuation pause. 1840 // * For both types of GC: 1841 // * Discovery is atomic - i.e. not concurrent. 1842 // * Reference discovery will not need a barrier. 1843 1844 MemRegion mr = reserved_region(); 1845 1846 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1847 1848 // Concurrent Mark ref processor 1849 _ref_processor_cm = 1850 new ReferenceProcessor(mr, // span 1851 mt_processing, 1852 // mt processing 1853 ParallelGCThreads, 1854 // degree of mt processing 1855 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 1856 // mt discovery 1857 MAX2(ParallelGCThreads, ConcGCThreads), 1858 // degree of mt discovery 1859 false, 1860 // Reference discovery is not atomic 1861 &_is_alive_closure_cm); 1862 // is alive closure 1863 // (for efficiency/performance) 1864 1865 // STW ref processor 1866 _ref_processor_stw = 1867 new ReferenceProcessor(mr, // span 1868 mt_processing, 1869 // mt processing 1870 ParallelGCThreads, 1871 // degree of mt processing 1872 (ParallelGCThreads > 1), 1873 // mt discovery 1874 ParallelGCThreads, 1875 // degree of mt discovery 1876 true, 1877 // Reference discovery is atomic 1878 &_is_alive_closure_stw); 1879 // is alive closure 1880 // (for efficiency/performance) 1881 } 1882 1883 CollectorPolicy* G1CollectedHeap::collector_policy() const { 1884 return _collector_policy; 1885 } 1886 1887 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1888 return &_soft_ref_policy; 1889 } 1890 1891 size_t G1CollectedHeap::capacity() const { 1892 return _hrm.length() * HeapRegion::GrainBytes; 1893 } 1894 1895 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1896 return _hrm.total_free_bytes(); 1897 } 1898 1899 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 1900 hr->reset_gc_time_stamp(); 1901 } 1902 1903 #ifndef PRODUCT 1904 1905 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 1906 private: 1907 unsigned _gc_time_stamp; 1908 bool _failures; 1909 1910 public: 1911 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 1912 _gc_time_stamp(gc_time_stamp), _failures(false) { } 1913 1914 virtual bool do_heap_region(HeapRegion* hr) { 1915 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 1916 if (_gc_time_stamp != region_gc_time_stamp) { 1917 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr), 1918 region_gc_time_stamp, _gc_time_stamp); 1919 _failures = true; 1920 } 1921 return false; 1922 } 1923 1924 bool failures() { return _failures; } 1925 }; 1926 1927 void G1CollectedHeap::check_gc_time_stamps() { 1928 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 1929 heap_region_iterate(&cl); 1930 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 1931 } 1932 #endif // PRODUCT 1933 1934 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) { 1935 _hot_card_cache->drain(cl, worker_i); 1936 } 1937 1938 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) { 1939 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 1940 size_t n_completed_buffers = 0; 1941 while (dcqs.apply_closure_during_gc(cl, worker_i)) { 1942 n_completed_buffers++; 1943 } 1944 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 1945 dcqs.clear_n_completed_buffers(); 1946 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 1947 } 1948 1949 // Computes the sum of the storage used by the various regions. 1950 size_t G1CollectedHeap::used() const { 1951 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1952 if (_archive_allocator != NULL) { 1953 result += _archive_allocator->used(); 1954 } 1955 return result; 1956 } 1957 1958 size_t G1CollectedHeap::used_unlocked() const { 1959 return _summary_bytes_used; 1960 } 1961 1962 class SumUsedClosure: public HeapRegionClosure { 1963 size_t _used; 1964 public: 1965 SumUsedClosure() : _used(0) {} 1966 bool do_heap_region(HeapRegion* r) { 1967 _used += r->used(); 1968 return false; 1969 } 1970 size_t result() { return _used; } 1971 }; 1972 1973 size_t G1CollectedHeap::recalculate_used() const { 1974 double recalculate_used_start = os::elapsedTime(); 1975 1976 SumUsedClosure blk; 1977 heap_region_iterate(&blk); 1978 1979 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 1980 return blk.result(); 1981 } 1982 1983 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1984 switch (cause) { 1985 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1986 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1987 case GCCause::_wb_conc_mark: return true; 1988 default : return false; 1989 } 1990 } 1991 1992 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 1993 switch (cause) { 1994 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 1995 case GCCause::_g1_humongous_allocation: return true; 1996 default: return is_user_requested_concurrent_full_gc(cause); 1997 } 1998 } 1999 2000 #ifndef PRODUCT 2001 void G1CollectedHeap::allocate_dummy_regions() { 2002 // Let's fill up most of the region 2003 size_t word_size = HeapRegion::GrainWords - 1024; 2004 // And as a result the region we'll allocate will be humongous. 2005 guarantee(is_humongous(word_size), "sanity"); 2006 2007 // _filler_array_max_size is set to humongous object threshold 2008 // but temporarily change it to use CollectedHeap::fill_with_object(). 2009 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2010 2011 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2012 // Let's use the existing mechanism for the allocation 2013 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2014 if (dummy_obj != NULL) { 2015 MemRegion mr(dummy_obj, word_size); 2016 CollectedHeap::fill_with_object(mr); 2017 } else { 2018 // If we can't allocate once, we probably cannot allocate 2019 // again. Let's get out of the loop. 2020 break; 2021 } 2022 } 2023 } 2024 #endif // !PRODUCT 2025 2026 void G1CollectedHeap::increment_old_marking_cycles_started() { 2027 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2028 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2029 "Wrong marking cycle count (started: %d, completed: %d)", 2030 _old_marking_cycles_started, _old_marking_cycles_completed); 2031 2032 _old_marking_cycles_started++; 2033 } 2034 2035 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2036 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2037 2038 // We assume that if concurrent == true, then the caller is a 2039 // concurrent thread that was joined the Suspendible Thread 2040 // Set. If there's ever a cheap way to check this, we should add an 2041 // assert here. 2042 2043 // Given that this method is called at the end of a Full GC or of a 2044 // concurrent cycle, and those can be nested (i.e., a Full GC can 2045 // interrupt a concurrent cycle), the number of full collections 2046 // completed should be either one (in the case where there was no 2047 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2048 // behind the number of full collections started. 2049 2050 // This is the case for the inner caller, i.e. a Full GC. 2051 assert(concurrent || 2052 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2053 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2054 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2055 "is inconsistent with _old_marking_cycles_completed = %u", 2056 _old_marking_cycles_started, _old_marking_cycles_completed); 2057 2058 // This is the case for the outer caller, i.e. the concurrent cycle. 2059 assert(!concurrent || 2060 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2061 "for outer caller (concurrent cycle): " 2062 "_old_marking_cycles_started = %u " 2063 "is inconsistent with _old_marking_cycles_completed = %u", 2064 _old_marking_cycles_started, _old_marking_cycles_completed); 2065 2066 _old_marking_cycles_completed += 1; 2067 2068 // We need to clear the "in_progress" flag in the CM thread before 2069 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2070 // is set) so that if a waiter requests another System.gc() it doesn't 2071 // incorrectly see that a marking cycle is still in progress. 2072 if (concurrent) { 2073 _cmThread->set_idle(); 2074 } 2075 2076 // This notify_all() will ensure that a thread that called 2077 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2078 // and it's waiting for a full GC to finish will be woken up. It is 2079 // waiting in VM_G1CollectForAllocation::doit_epilogue(). 2080 FullGCCount_lock->notify_all(); 2081 } 2082 2083 void G1CollectedHeap::collect(GCCause::Cause cause) { 2084 assert_heap_not_locked(); 2085 2086 uint gc_count_before; 2087 uint old_marking_count_before; 2088 uint full_gc_count_before; 2089 bool retry_gc; 2090 2091 do { 2092 retry_gc = false; 2093 2094 { 2095 MutexLocker ml(Heap_lock); 2096 2097 // Read the GC count while holding the Heap_lock 2098 gc_count_before = total_collections(); 2099 full_gc_count_before = total_full_collections(); 2100 old_marking_count_before = _old_marking_cycles_started; 2101 } 2102 2103 if (should_do_concurrent_full_gc(cause)) { 2104 // Schedule an initial-mark evacuation pause that will start a 2105 // concurrent cycle. We're setting word_size to 0 which means that 2106 // we are not requesting a post-GC allocation. 2107 VM_G1CollectForAllocation op(0, /* word_size */ 2108 gc_count_before, 2109 cause, 2110 true, /* should_initiate_conc_mark */ 2111 g1_policy()->max_pause_time_ms()); 2112 VMThread::execute(&op); 2113 if (!op.pause_succeeded()) { 2114 if (old_marking_count_before == _old_marking_cycles_started) { 2115 retry_gc = op.should_retry_gc(); 2116 } else { 2117 // A Full GC happened while we were trying to schedule the 2118 // initial-mark GC. No point in starting a new cycle given 2119 // that the whole heap was collected anyway. 2120 } 2121 2122 if (retry_gc) { 2123 if (GCLocker::is_active_and_needs_gc()) { 2124 GCLocker::stall_until_clear(); 2125 } 2126 } 2127 } 2128 } else { 2129 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2130 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2131 2132 // Schedule a standard evacuation pause. We're setting word_size 2133 // to 0 which means that we are not requesting a post-GC allocation. 2134 VM_G1CollectForAllocation op(0, /* word_size */ 2135 gc_count_before, 2136 cause, 2137 false, /* should_initiate_conc_mark */ 2138 g1_policy()->max_pause_time_ms()); 2139 VMThread::execute(&op); 2140 } else { 2141 // Schedule a Full GC. 2142 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2143 VMThread::execute(&op); 2144 } 2145 } 2146 } while (retry_gc); 2147 } 2148 2149 bool G1CollectedHeap::is_in(const void* p) const { 2150 if (_hrm.reserved().contains(p)) { 2151 // Given that we know that p is in the reserved space, 2152 // heap_region_containing() should successfully 2153 // return the containing region. 2154 HeapRegion* hr = heap_region_containing(p); 2155 return hr->is_in(p); 2156 } else { 2157 return false; 2158 } 2159 } 2160 2161 #ifdef ASSERT 2162 bool G1CollectedHeap::is_in_exact(const void* p) const { 2163 bool contains = reserved_region().contains(p); 2164 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2165 if (contains && available) { 2166 return true; 2167 } else { 2168 return false; 2169 } 2170 } 2171 #endif 2172 2173 // Iteration functions. 2174 2175 // Iterates an ObjectClosure over all objects within a HeapRegion. 2176 2177 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2178 ObjectClosure* _cl; 2179 public: 2180 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2181 bool do_heap_region(HeapRegion* r) { 2182 if (!r->is_continues_humongous()) { 2183 r->object_iterate(_cl); 2184 } 2185 return false; 2186 } 2187 }; 2188 2189 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2190 IterateObjectClosureRegionClosure blk(cl); 2191 heap_region_iterate(&blk); 2192 } 2193 2194 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2195 _hrm.iterate(cl); 2196 } 2197 2198 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2199 HeapRegionClaimer *hrclaimer, 2200 uint worker_id) const { 2201 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2202 } 2203 2204 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2205 HeapRegionClaimer *hrclaimer) const { 2206 _hrm.par_iterate(cl, hrclaimer, 0); 2207 } 2208 2209 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2210 _collection_set.iterate(cl); 2211 } 2212 2213 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) { 2214 _collection_set.iterate_from(cl, worker_id, workers()->active_workers()); 2215 } 2216 2217 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2218 HeapRegion* hr = heap_region_containing(addr); 2219 return hr->block_start(addr); 2220 } 2221 2222 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2223 HeapRegion* hr = heap_region_containing(addr); 2224 return hr->block_size(addr); 2225 } 2226 2227 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2228 HeapRegion* hr = heap_region_containing(addr); 2229 return hr->block_is_obj(addr); 2230 } 2231 2232 bool G1CollectedHeap::supports_tlab_allocation() const { 2233 return true; 2234 } 2235 2236 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2237 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2238 } 2239 2240 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2241 return _eden.length() * HeapRegion::GrainBytes; 2242 } 2243 2244 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2245 // must be equal to the humongous object limit. 2246 size_t G1CollectedHeap::max_tlab_size() const { 2247 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2248 } 2249 2250 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2251 return _allocator->unsafe_max_tlab_alloc(); 2252 } 2253 2254 size_t G1CollectedHeap::max_capacity() const { 2255 return _hrm.reserved().byte_size(); 2256 } 2257 2258 jlong G1CollectedHeap::millis_since_last_gc() { 2259 // See the notes in GenCollectedHeap::millis_since_last_gc() 2260 // for more information about the implementation. 2261 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2262 _g1_policy->collection_pause_end_millis(); 2263 if (ret_val < 0) { 2264 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2265 ". returning zero instead.", ret_val); 2266 return 0; 2267 } 2268 return ret_val; 2269 } 2270 2271 void G1CollectedHeap::prepare_for_verify() { 2272 _verifier->prepare_for_verify(); 2273 } 2274 2275 void G1CollectedHeap::verify(VerifyOption vo) { 2276 _verifier->verify(vo); 2277 } 2278 2279 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2280 return true; 2281 } 2282 2283 const char* const* G1CollectedHeap::concurrent_phases() const { 2284 return _cmThread->concurrent_phases(); 2285 } 2286 2287 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2288 return _cmThread->request_concurrent_phase(phase); 2289 } 2290 2291 class PrintRegionClosure: public HeapRegionClosure { 2292 outputStream* _st; 2293 public: 2294 PrintRegionClosure(outputStream* st) : _st(st) {} 2295 bool do_heap_region(HeapRegion* r) { 2296 r->print_on(_st); 2297 return false; 2298 } 2299 }; 2300 2301 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2302 const HeapRegion* hr, 2303 const VerifyOption vo) const { 2304 switch (vo) { 2305 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2306 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2307 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2308 default: ShouldNotReachHere(); 2309 } 2310 return false; // keep some compilers happy 2311 } 2312 2313 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2314 const VerifyOption vo) const { 2315 switch (vo) { 2316 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2317 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2318 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2319 default: ShouldNotReachHere(); 2320 } 2321 return false; // keep some compilers happy 2322 } 2323 2324 void G1CollectedHeap::print_heap_regions() const { 2325 LogTarget(Trace, gc, heap, region) lt; 2326 if (lt.is_enabled()) { 2327 LogStream ls(lt); 2328 print_regions_on(&ls); 2329 } 2330 } 2331 2332 void G1CollectedHeap::print_on(outputStream* st) const { 2333 st->print(" %-20s", "garbage-first heap"); 2334 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2335 capacity()/K, used_unlocked()/K); 2336 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2337 p2i(_hrm.reserved().start()), 2338 p2i(_hrm.reserved().end())); 2339 st->cr(); 2340 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2341 uint young_regions = young_regions_count(); 2342 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2343 (size_t) young_regions * HeapRegion::GrainBytes / K); 2344 uint survivor_regions = survivor_regions_count(); 2345 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2346 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2347 st->cr(); 2348 MetaspaceAux::print_on(st); 2349 } 2350 2351 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2352 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2353 "HS=humongous(starts), HC=humongous(continues), " 2354 "CS=collection set, F=free, A=archive, TS=gc time stamp, " 2355 "TAMS=top-at-mark-start (previous, next)"); 2356 PrintRegionClosure blk(st); 2357 heap_region_iterate(&blk); 2358 } 2359 2360 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2361 print_on(st); 2362 2363 // Print the per-region information. 2364 print_regions_on(st); 2365 } 2366 2367 void G1CollectedHeap::print_on_error(outputStream* st) const { 2368 this->CollectedHeap::print_on_error(st); 2369 2370 if (_cm != NULL) { 2371 st->cr(); 2372 _cm->print_on_error(st); 2373 } 2374 } 2375 2376 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2377 workers()->print_worker_threads_on(st); 2378 _cmThread->print_on(st); 2379 st->cr(); 2380 _cm->print_worker_threads_on(st); 2381 _cr->print_threads_on(st); 2382 _young_gen_sampling_thread->print_on(st); 2383 if (G1StringDedup::is_enabled()) { 2384 G1StringDedup::print_worker_threads_on(st); 2385 } 2386 } 2387 2388 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2389 workers()->threads_do(tc); 2390 tc->do_thread(_cmThread); 2391 _cm->threads_do(tc); 2392 _cr->threads_do(tc); 2393 tc->do_thread(_young_gen_sampling_thread); 2394 if (G1StringDedup::is_enabled()) { 2395 G1StringDedup::threads_do(tc); 2396 } 2397 } 2398 2399 void G1CollectedHeap::print_tracing_info() const { 2400 g1_rem_set()->print_summary_info(); 2401 concurrent_mark()->print_summary_info(); 2402 } 2403 2404 #ifndef PRODUCT 2405 // Helpful for debugging RSet issues. 2406 2407 class PrintRSetsClosure : public HeapRegionClosure { 2408 private: 2409 const char* _msg; 2410 size_t _occupied_sum; 2411 2412 public: 2413 bool do_heap_region(HeapRegion* r) { 2414 HeapRegionRemSet* hrrs = r->rem_set(); 2415 size_t occupied = hrrs->occupied(); 2416 _occupied_sum += occupied; 2417 2418 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2419 if (occupied == 0) { 2420 tty->print_cr(" RSet is empty"); 2421 } else { 2422 hrrs->print(); 2423 } 2424 tty->print_cr("----------"); 2425 return false; 2426 } 2427 2428 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2429 tty->cr(); 2430 tty->print_cr("========================================"); 2431 tty->print_cr("%s", msg); 2432 tty->cr(); 2433 } 2434 2435 ~PrintRSetsClosure() { 2436 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2437 tty->print_cr("========================================"); 2438 tty->cr(); 2439 } 2440 }; 2441 2442 void G1CollectedHeap::print_cset_rsets() { 2443 PrintRSetsClosure cl("Printing CSet RSets"); 2444 collection_set_iterate(&cl); 2445 } 2446 2447 void G1CollectedHeap::print_all_rsets() { 2448 PrintRSetsClosure cl("Printing All RSets");; 2449 heap_region_iterate(&cl); 2450 } 2451 #endif // PRODUCT 2452 2453 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2454 2455 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes; 2456 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes; 2457 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2458 2459 size_t eden_capacity_bytes = 2460 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2461 2462 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2463 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2464 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2465 } 2466 2467 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2468 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2469 stats->unused(), stats->used(), stats->region_end_waste(), 2470 stats->regions_filled(), stats->direct_allocated(), 2471 stats->failure_used(), stats->failure_waste()); 2472 } 2473 2474 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2475 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2476 gc_tracer->report_gc_heap_summary(when, heap_summary); 2477 2478 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2479 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2480 } 2481 2482 G1CollectedHeap* G1CollectedHeap::heap() { 2483 CollectedHeap* heap = Universe::heap(); 2484 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2485 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); 2486 return (G1CollectedHeap*)heap; 2487 } 2488 2489 void G1CollectedHeap::gc_prologue(bool full) { 2490 // always_do_update_barrier = false; 2491 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2492 2493 // This summary needs to be printed before incrementing total collections. 2494 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2495 2496 // Update common counters. 2497 increment_total_collections(full /* full gc */); 2498 if (full) { 2499 increment_old_marking_cycles_started(); 2500 reset_gc_time_stamp(); 2501 } else { 2502 increment_gc_time_stamp(); 2503 } 2504 2505 // Fill TLAB's and such 2506 double start = os::elapsedTime(); 2507 accumulate_statistics_all_tlabs(); 2508 ensure_parsability(true); 2509 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2510 } 2511 2512 void G1CollectedHeap::gc_epilogue(bool full) { 2513 // Update common counters. 2514 if (full) { 2515 // Update the number of full collections that have been completed. 2516 increment_old_marking_cycles_completed(false /* concurrent */); 2517 } 2518 2519 // We are at the end of the GC. Total collections has already been increased. 2520 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2521 2522 // FIXME: what is this about? 2523 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2524 // is set. 2525 #if COMPILER2_OR_JVMCI 2526 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2527 #endif 2528 // always_do_update_barrier = true; 2529 2530 double start = os::elapsedTime(); 2531 resize_all_tlabs(); 2532 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2533 2534 MemoryService::track_memory_usage(); 2535 // We have just completed a GC. Update the soft reference 2536 // policy with the new heap occupancy 2537 Universe::update_heap_info_at_gc(); 2538 } 2539 2540 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2541 uint gc_count_before, 2542 bool* succeeded, 2543 GCCause::Cause gc_cause) { 2544 assert_heap_not_locked_and_not_at_safepoint(); 2545 VM_G1CollectForAllocation op(word_size, 2546 gc_count_before, 2547 gc_cause, 2548 false, /* should_initiate_conc_mark */ 2549 g1_policy()->max_pause_time_ms()); 2550 VMThread::execute(&op); 2551 2552 HeapWord* result = op.result(); 2553 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 2554 assert(result == NULL || ret_succeeded, 2555 "the result should be NULL if the VM did not succeed"); 2556 *succeeded = ret_succeeded; 2557 2558 assert_heap_not_locked(); 2559 return result; 2560 } 2561 2562 void 2563 G1CollectedHeap::doConcurrentMark() { 2564 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 2565 if (!_cmThread->in_progress()) { 2566 _cmThread->set_started(); 2567 CGC_lock->notify(); 2568 } 2569 } 2570 2571 size_t G1CollectedHeap::pending_card_num() { 2572 size_t extra_cards = 0; 2573 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) { 2574 DirtyCardQueue& dcq = curr->dirty_card_queue(); 2575 extra_cards += dcq.size(); 2576 } 2577 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2578 size_t buffer_size = dcqs.buffer_size(); 2579 size_t buffer_num = dcqs.completed_buffers_num(); 2580 2581 return buffer_size * buffer_num + extra_cards; 2582 } 2583 2584 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 2585 private: 2586 size_t _total_humongous; 2587 size_t _candidate_humongous; 2588 2589 DirtyCardQueue _dcq; 2590 2591 // We don't nominate objects with many remembered set entries, on 2592 // the assumption that such objects are likely still live. 2593 bool is_remset_small(HeapRegion* region) const { 2594 HeapRegionRemSet* const rset = region->rem_set(); 2595 return G1EagerReclaimHumongousObjectsWithStaleRefs 2596 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) 2597 : rset->is_empty(); 2598 } 2599 2600 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { 2601 assert(region->is_starts_humongous(), "Must start a humongous object"); 2602 2603 oop obj = oop(region->bottom()); 2604 2605 // Dead objects cannot be eager reclaim candidates. Due to class 2606 // unloading it is unsafe to query their classes so we return early. 2607 if (heap->is_obj_dead(obj, region)) { 2608 return false; 2609 } 2610 2611 // Candidate selection must satisfy the following constraints 2612 // while concurrent marking is in progress: 2613 // 2614 // * In order to maintain SATB invariants, an object must not be 2615 // reclaimed if it was allocated before the start of marking and 2616 // has not had its references scanned. Such an object must have 2617 // its references (including type metadata) scanned to ensure no 2618 // live objects are missed by the marking process. Objects 2619 // allocated after the start of concurrent marking don't need to 2620 // be scanned. 2621 // 2622 // * An object must not be reclaimed if it is on the concurrent 2623 // mark stack. Objects allocated after the start of concurrent 2624 // marking are never pushed on the mark stack. 2625 // 2626 // Nominating only objects allocated after the start of concurrent 2627 // marking is sufficient to meet both constraints. This may miss 2628 // some objects that satisfy the constraints, but the marking data 2629 // structures don't support efficiently performing the needed 2630 // additional tests or scrubbing of the mark stack. 2631 // 2632 // However, we presently only nominate is_typeArray() objects. 2633 // A humongous object containing references induces remembered 2634 // set entries on other regions. In order to reclaim such an 2635 // object, those remembered sets would need to be cleaned up. 2636 // 2637 // We also treat is_typeArray() objects specially, allowing them 2638 // to be reclaimed even if allocated before the start of 2639 // concurrent mark. For this we rely on mark stack insertion to 2640 // exclude is_typeArray() objects, preventing reclaiming an object 2641 // that is in the mark stack. We also rely on the metadata for 2642 // such objects to be built-in and so ensured to be kept live. 2643 // Frequent allocation and drop of large binary blobs is an 2644 // important use case for eager reclaim, and this special handling 2645 // may reduce needed headroom. 2646 2647 return obj->is_typeArray() && is_remset_small(region); 2648 } 2649 2650 public: 2651 RegisterHumongousWithInCSetFastTestClosure() 2652 : _total_humongous(0), 2653 _candidate_humongous(0), 2654 _dcq(&JavaThread::dirty_card_queue_set()) { 2655 } 2656 2657 virtual bool do_heap_region(HeapRegion* r) { 2658 if (!r->is_starts_humongous()) { 2659 return false; 2660 } 2661 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2662 2663 bool is_candidate = humongous_region_is_candidate(g1h, r); 2664 uint rindex = r->hrm_index(); 2665 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2666 if (is_candidate) { 2667 _candidate_humongous++; 2668 g1h->register_humongous_region_with_cset(rindex); 2669 // Is_candidate already filters out humongous object with large remembered sets. 2670 // If we have a humongous object with a few remembered sets, we simply flush these 2671 // remembered set entries into the DCQS. That will result in automatic 2672 // re-evaluation of their remembered set entries during the following evacuation 2673 // phase. 2674 if (!r->rem_set()->is_empty()) { 2675 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 2676 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 2677 G1CardTable* ct = g1h->card_table(); 2678 HeapRegionRemSetIterator hrrs(r->rem_set()); 2679 size_t card_index; 2680 while (hrrs.has_next(card_index)) { 2681 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index); 2682 // The remembered set might contain references to already freed 2683 // regions. Filter out such entries to avoid failing card table 2684 // verification. 2685 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) { 2686 if (*card_ptr != G1CardTable::dirty_card_val()) { 2687 *card_ptr = G1CardTable::dirty_card_val(); 2688 _dcq.enqueue(card_ptr); 2689 } 2690 } 2691 } 2692 assert(hrrs.n_yielded() == r->rem_set()->occupied(), 2693 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", 2694 hrrs.n_yielded(), r->rem_set()->occupied()); 2695 r->rem_set()->clear_locked(); 2696 } 2697 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 2698 } 2699 _total_humongous++; 2700 2701 return false; 2702 } 2703 2704 size_t total_humongous() const { return _total_humongous; } 2705 size_t candidate_humongous() const { return _candidate_humongous; } 2706 2707 void flush_rem_set_entries() { _dcq.flush(); } 2708 }; 2709 2710 void G1CollectedHeap::register_humongous_regions_with_cset() { 2711 if (!G1EagerReclaimHumongousObjects) { 2712 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 2713 return; 2714 } 2715 double time = os::elapsed_counter(); 2716 2717 // Collect reclaim candidate information and register candidates with cset. 2718 RegisterHumongousWithInCSetFastTestClosure cl; 2719 heap_region_iterate(&cl); 2720 2721 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 2722 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 2723 cl.total_humongous(), 2724 cl.candidate_humongous()); 2725 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2726 2727 // Finally flush all remembered set entries to re-check into the global DCQS. 2728 cl.flush_rem_set_entries(); 2729 } 2730 2731 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2732 public: 2733 bool do_heap_region(HeapRegion* hr) { 2734 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2735 hr->verify_rem_set(); 2736 } 2737 return false; 2738 } 2739 }; 2740 2741 uint G1CollectedHeap::num_task_queues() const { 2742 return _task_queues->size(); 2743 } 2744 2745 #if TASKQUEUE_STATS 2746 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2747 st->print_raw_cr("GC Task Stats"); 2748 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2749 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2750 } 2751 2752 void G1CollectedHeap::print_taskqueue_stats() const { 2753 if (!log_is_enabled(Trace, gc, task, stats)) { 2754 return; 2755 } 2756 Log(gc, task, stats) log; 2757 ResourceMark rm; 2758 LogStream ls(log.trace()); 2759 outputStream* st = &ls; 2760 2761 print_taskqueue_stats_hdr(st); 2762 2763 TaskQueueStats totals; 2764 const uint n = num_task_queues(); 2765 for (uint i = 0; i < n; ++i) { 2766 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2767 totals += task_queue(i)->stats; 2768 } 2769 st->print_raw("tot "); totals.print(st); st->cr(); 2770 2771 DEBUG_ONLY(totals.verify()); 2772 } 2773 2774 void G1CollectedHeap::reset_taskqueue_stats() { 2775 const uint n = num_task_queues(); 2776 for (uint i = 0; i < n; ++i) { 2777 task_queue(i)->stats.reset(); 2778 } 2779 } 2780 #endif // TASKQUEUE_STATS 2781 2782 void G1CollectedHeap::wait_for_root_region_scanning() { 2783 double scan_wait_start = os::elapsedTime(); 2784 // We have to wait until the CM threads finish scanning the 2785 // root regions as it's the only way to ensure that all the 2786 // objects on them have been correctly scanned before we start 2787 // moving them during the GC. 2788 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2789 double wait_time_ms = 0.0; 2790 if (waited) { 2791 double scan_wait_end = os::elapsedTime(); 2792 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2793 } 2794 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2795 } 2796 2797 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2798 private: 2799 G1HRPrinter* _hr_printer; 2800 public: 2801 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2802 2803 virtual bool do_heap_region(HeapRegion* r) { 2804 _hr_printer->cset(r); 2805 return false; 2806 } 2807 }; 2808 2809 void G1CollectedHeap::start_new_collection_set() { 2810 collection_set()->start_incremental_building(); 2811 2812 clear_cset_fast_test(); 2813 2814 guarantee(_eden.length() == 0, "eden should have been cleared"); 2815 g1_policy()->transfer_survivors_to_cset(survivor()); 2816 } 2817 2818 bool 2819 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2820 assert_at_safepoint_on_vm_thread(); 2821 guarantee(!is_gc_active(), "collection is not reentrant"); 2822 2823 if (GCLocker::check_active_before_gc()) { 2824 return false; 2825 } 2826 2827 _gc_timer_stw->register_gc_start(); 2828 2829 GCIdMark gc_id_mark; 2830 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2831 2832 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2833 ResourceMark rm; 2834 2835 g1_policy()->note_gc_start(); 2836 2837 wait_for_root_region_scanning(); 2838 2839 print_heap_before_gc(); 2840 print_heap_regions(); 2841 trace_heap_before_gc(_gc_tracer_stw); 2842 2843 _verifier->verify_region_sets_optional(); 2844 _verifier->verify_dirty_young_regions(); 2845 2846 // We should not be doing initial mark unless the conc mark thread is running 2847 if (!_cmThread->should_terminate()) { 2848 // This call will decide whether this pause is an initial-mark 2849 // pause. If it is, during_initial_mark_pause() will return true 2850 // for the duration of this pause. 2851 g1_policy()->decide_on_conc_mark_initiation(); 2852 } 2853 2854 // We do not allow initial-mark to be piggy-backed on a mixed GC. 2855 assert(!collector_state()->during_initial_mark_pause() || 2856 collector_state()->gcs_are_young(), "sanity"); 2857 2858 // We also do not allow mixed GCs during marking. 2859 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity"); 2860 2861 // Record whether this pause is an initial mark. When the current 2862 // thread has completed its logging output and it's safe to signal 2863 // the CM thread, the flag's value in the policy has been reset. 2864 bool should_start_conc_mark = collector_state()->during_initial_mark_pause(); 2865 2866 // Inner scope for scope based logging, timers, and stats collection 2867 { 2868 EvacuationInfo evacuation_info; 2869 2870 if (collector_state()->during_initial_mark_pause()) { 2871 // We are about to start a marking cycle, so we increment the 2872 // full collection counter. 2873 increment_old_marking_cycles_started(); 2874 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2875 } 2876 2877 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 2878 2879 GCTraceCPUTime tcpu; 2880 2881 G1HeapVerifier::G1VerifyType verify_type; 2882 FormatBuffer<> gc_string("Pause "); 2883 if (collector_state()->during_initial_mark_pause()) { 2884 gc_string.append("Initial Mark"); 2885 verify_type = G1HeapVerifier::G1VerifyInitialMark; 2886 } else if (collector_state()->gcs_are_young()) { 2887 gc_string.append("Young"); 2888 verify_type = G1HeapVerifier::G1VerifyYoungOnly; 2889 } else { 2890 gc_string.append("Mixed"); 2891 verify_type = G1HeapVerifier::G1VerifyMixed; 2892 } 2893 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true); 2894 2895 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 2896 workers()->active_workers(), 2897 Threads::number_of_non_daemon_threads()); 2898 workers()->update_active_workers(active_workers); 2899 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 2900 2901 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 2902 TraceMemoryManagerStats tms(&_memory_manager, gc_cause()); 2903 2904 // If the secondary_free_list is not empty, append it to the 2905 // free_list. No need to wait for the cleanup operation to finish; 2906 // the region allocation code will check the secondary_free_list 2907 // and wait if necessary. If the G1StressConcRegionFreeing flag is 2908 // set, skip this step so that the region allocation code has to 2909 // get entries from the secondary_free_list. 2910 if (!G1StressConcRegionFreeing) { 2911 append_secondary_free_list_if_not_empty_with_lock(); 2912 } 2913 2914 G1HeapTransition heap_transition(this); 2915 size_t heap_used_bytes_before_gc = used(); 2916 2917 // Don't dynamically change the number of GC threads this early. A value of 2918 // 0 is used to indicate serial work. When parallel work is done, 2919 // it will be set. 2920 2921 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 2922 IsGCActiveMark x; 2923 2924 gc_prologue(false); 2925 2926 if (VerifyRememberedSets) { 2927 log_info(gc, verify)("[Verifying RemSets before GC]"); 2928 VerifyRegionRemSetClosure v_cl; 2929 heap_region_iterate(&v_cl); 2930 } 2931 2932 _verifier->verify_before_gc(verify_type); 2933 2934 _verifier->check_bitmaps("GC Start"); 2935 2936 #if COMPILER2_OR_JVMCI 2937 DerivedPointerTable::clear(); 2938 #endif 2939 2940 // Please see comment in g1CollectedHeap.hpp and 2941 // G1CollectedHeap::ref_processing_init() to see how 2942 // reference processing currently works in G1. 2943 2944 // Enable discovery in the STW reference processor 2945 if (g1_policy()->should_process_references()) { 2946 ref_processor_stw()->enable_discovery(); 2947 } else { 2948 ref_processor_stw()->disable_discovery(); 2949 } 2950 2951 { 2952 // We want to temporarily turn off discovery by the 2953 // CM ref processor, if necessary, and turn it back on 2954 // on again later if we do. Using a scoped 2955 // NoRefDiscovery object will do this. 2956 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 2957 2958 // Forget the current alloc region (we might even choose it to be part 2959 // of the collection set!). 2960 _allocator->release_mutator_alloc_region(); 2961 2962 // This timing is only used by the ergonomics to handle our pause target. 2963 // It is unclear why this should not include the full pause. We will 2964 // investigate this in CR 7178365. 2965 // 2966 // Preserving the old comment here if that helps the investigation: 2967 // 2968 // The elapsed time induced by the start time below deliberately elides 2969 // the possible verification above. 2970 double sample_start_time_sec = os::elapsedTime(); 2971 2972 g1_policy()->record_collection_pause_start(sample_start_time_sec); 2973 2974 if (collector_state()->during_initial_mark_pause()) { 2975 concurrent_mark()->checkpoint_roots_initial_pre(); 2976 } 2977 2978 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor); 2979 2980 evacuation_info.set_collectionset_regions(collection_set()->region_length()); 2981 2982 // Make sure the remembered sets are up to date. This needs to be 2983 // done before register_humongous_regions_with_cset(), because the 2984 // remembered sets are used there to choose eager reclaim candidates. 2985 // If the remembered sets are not up to date we might miss some 2986 // entries that need to be handled. 2987 g1_rem_set()->cleanupHRRS(); 2988 2989 register_humongous_regions_with_cset(); 2990 2991 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table."); 2992 2993 // We call this after finalize_cset() to 2994 // ensure that the CSet has been finalized. 2995 _cm->verify_no_cset_oops(); 2996 2997 if (_hr_printer.is_active()) { 2998 G1PrintCollectionSetClosure cl(&_hr_printer); 2999 _collection_set.iterate(&cl); 3000 } 3001 3002 // Initialize the GC alloc regions. 3003 _allocator->init_gc_alloc_regions(evacuation_info); 3004 3005 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length()); 3006 pre_evacuate_collection_set(); 3007 3008 // Actually do the work... 3009 evacuate_collection_set(&per_thread_states); 3010 3011 post_evacuate_collection_set(evacuation_info, &per_thread_states); 3012 3013 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 3014 free_collection_set(&_collection_set, evacuation_info, surviving_young_words); 3015 3016 eagerly_reclaim_humongous_regions(); 3017 3018 record_obj_copy_mem_stats(); 3019 _survivor_evac_stats.adjust_desired_plab_sz(); 3020 _old_evac_stats.adjust_desired_plab_sz(); 3021 3022 double start = os::elapsedTime(); 3023 start_new_collection_set(); 3024 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 3025 3026 if (evacuation_failed()) { 3027 set_used(recalculate_used()); 3028 if (_archive_allocator != NULL) { 3029 _archive_allocator->clear_used(); 3030 } 3031 for (uint i = 0; i < ParallelGCThreads; i++) { 3032 if (_evacuation_failed_info_array[i].has_failed()) { 3033 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3034 } 3035 } 3036 } else { 3037 // The "used" of the the collection set have already been subtracted 3038 // when they were freed. Add in the bytes evacuated. 3039 increase_used(g1_policy()->bytes_copied_during_gc()); 3040 } 3041 3042 if (collector_state()->during_initial_mark_pause()) { 3043 // We have to do this before we notify the CM threads that 3044 // they can start working to make sure that all the 3045 // appropriate initialization is done on the CM object. 3046 concurrent_mark()->checkpoint_roots_initial_post(); 3047 collector_state()->set_mark_in_progress(true); 3048 // Note that we don't actually trigger the CM thread at 3049 // this point. We do that later when we're sure that 3050 // the current thread has completed its logging output. 3051 } 3052 3053 allocate_dummy_regions(); 3054 3055 _allocator->init_mutator_alloc_region(); 3056 3057 { 3058 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 3059 if (expand_bytes > 0) { 3060 size_t bytes_before = capacity(); 3061 // No need for an ergo logging here, 3062 // expansion_amount() does this when it returns a value > 0. 3063 double expand_ms; 3064 if (!expand(expand_bytes, _workers, &expand_ms)) { 3065 // We failed to expand the heap. Cannot do anything about it. 3066 } 3067 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 3068 } 3069 } 3070 3071 // We redo the verification but now wrt to the new CSet which 3072 // has just got initialized after the previous CSet was freed. 3073 _cm->verify_no_cset_oops(); 3074 3075 // This timing is only used by the ergonomics to handle our pause target. 3076 // It is unclear why this should not include the full pause. We will 3077 // investigate this in CR 7178365. 3078 double sample_end_time_sec = os::elapsedTime(); 3079 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3080 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards); 3081 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc); 3082 3083 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3084 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 3085 3086 if (VerifyRememberedSets) { 3087 log_info(gc, verify)("[Verifying RemSets after GC]"); 3088 VerifyRegionRemSetClosure v_cl; 3089 heap_region_iterate(&v_cl); 3090 } 3091 3092 _verifier->verify_after_gc(verify_type); 3093 _verifier->check_bitmaps("GC End"); 3094 3095 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 3096 ref_processor_stw()->verify_no_references_recorded(); 3097 3098 // CM reference discovery will be re-enabled if necessary. 3099 } 3100 3101 #ifdef TRACESPINNING 3102 ParallelTaskTerminator::print_termination_counts(); 3103 #endif 3104 3105 gc_epilogue(false); 3106 } 3107 3108 // Print the remainder of the GC log output. 3109 if (evacuation_failed()) { 3110 log_info(gc)("To-space exhausted"); 3111 } 3112 3113 g1_policy()->print_phases(); 3114 heap_transition.print(); 3115 3116 // It is not yet to safe to tell the concurrent mark to 3117 // start as we have some optional output below. We don't want the 3118 // output from the concurrent mark thread interfering with this 3119 // logging output either. 3120 3121 _hrm.verify_optional(); 3122 _verifier->verify_region_sets_optional(); 3123 3124 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3125 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3126 3127 print_heap_after_gc(); 3128 print_heap_regions(); 3129 trace_heap_after_gc(_gc_tracer_stw); 3130 3131 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3132 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3133 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3134 // before any GC notifications are raised. 3135 g1mm()->update_sizes(); 3136 3137 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3138 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 3139 _gc_timer_stw->register_gc_end(); 3140 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3141 } 3142 // It should now be safe to tell the concurrent mark thread to start 3143 // without its logging output interfering with the logging output 3144 // that came from the pause. 3145 3146 if (should_start_conc_mark) { 3147 // CAUTION: after the doConcurrentMark() call below, 3148 // the concurrent marking thread(s) could be running 3149 // concurrently with us. Make sure that anything after 3150 // this point does not assume that we are the only GC thread 3151 // running. Note: of course, the actual marking work will 3152 // not start until the safepoint itself is released in 3153 // SuspendibleThreadSet::desynchronize(). 3154 doConcurrentMark(); 3155 } 3156 3157 return true; 3158 } 3159 3160 void G1CollectedHeap::remove_self_forwarding_pointers() { 3161 G1ParRemoveSelfForwardPtrsTask rsfp_task; 3162 workers()->run_task(&rsfp_task); 3163 } 3164 3165 void G1CollectedHeap::restore_after_evac_failure() { 3166 double remove_self_forwards_start = os::elapsedTime(); 3167 3168 remove_self_forwarding_pointers(); 3169 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3170 _preserved_marks_set.restore(&task_executor); 3171 3172 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3173 } 3174 3175 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 3176 if (!_evacuation_failed) { 3177 _evacuation_failed = true; 3178 } 3179 3180 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3181 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3182 } 3183 3184 bool G1ParEvacuateFollowersClosure::offer_termination() { 3185 G1ParScanThreadState* const pss = par_scan_state(); 3186 start_term_time(); 3187 const bool res = terminator()->offer_termination(); 3188 end_term_time(); 3189 return res; 3190 } 3191 3192 void G1ParEvacuateFollowersClosure::do_void() { 3193 G1ParScanThreadState* const pss = par_scan_state(); 3194 pss->trim_queue(); 3195 do { 3196 pss->steal_and_trim_queue(queues()); 3197 } while (!offer_termination()); 3198 } 3199 3200 class G1ParTask : public AbstractGangTask { 3201 protected: 3202 G1CollectedHeap* _g1h; 3203 G1ParScanThreadStateSet* _pss; 3204 RefToScanQueueSet* _queues; 3205 G1RootProcessor* _root_processor; 3206 ParallelTaskTerminator _terminator; 3207 uint _n_workers; 3208 3209 public: 3210 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 3211 : AbstractGangTask("G1 collection"), 3212 _g1h(g1h), 3213 _pss(per_thread_states), 3214 _queues(task_queues), 3215 _root_processor(root_processor), 3216 _terminator(n_workers, _queues), 3217 _n_workers(n_workers) 3218 {} 3219 3220 void work(uint worker_id) { 3221 if (worker_id >= _n_workers) return; // no work needed this round 3222 3223 double start_sec = os::elapsedTime(); 3224 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 3225 3226 { 3227 ResourceMark rm; 3228 HandleMark hm; 3229 3230 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 3231 3232 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3233 pss->set_ref_processor(rp); 3234 3235 double start_strong_roots_sec = os::elapsedTime(); 3236 3237 _root_processor->evacuate_roots(pss->closures(), worker_id); 3238 3239 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid 3240 // treating the nmethods visited to act as roots for concurrent marking. 3241 // We only want to make sure that the oops in the nmethods are adjusted with regard to the 3242 // objects copied by the current evacuation. 3243 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, 3244 pss->closures()->weak_codeblobs(), 3245 worker_id); 3246 3247 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 3248 3249 double term_sec = 0.0; 3250 size_t evac_term_attempts = 0; 3251 { 3252 double start = os::elapsedTime(); 3253 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator); 3254 evac.do_void(); 3255 3256 evac_term_attempts = evac.term_attempts(); 3257 term_sec = evac.term_time(); 3258 double elapsed_sec = os::elapsedTime() - start; 3259 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 3260 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 3261 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 3262 } 3263 3264 assert(pss->queue_is_empty(), "should be empty"); 3265 3266 if (log_is_enabled(Debug, gc, task, stats)) { 3267 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3268 size_t lab_waste; 3269 size_t lab_undo_waste; 3270 pss->waste(lab_waste, lab_undo_waste); 3271 _g1h->print_termination_stats(worker_id, 3272 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 3273 strong_roots_sec * 1000.0, /* strong roots time */ 3274 term_sec * 1000.0, /* evac term time */ 3275 evac_term_attempts, /* evac term attempts */ 3276 lab_waste, /* alloc buffer waste */ 3277 lab_undo_waste /* undo waste */ 3278 ); 3279 } 3280 3281 // Close the inner scope so that the ResourceMark and HandleMark 3282 // destructors are executed here and are included as part of the 3283 // "GC Worker Time". 3284 } 3285 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 3286 } 3287 }; 3288 3289 void G1CollectedHeap::print_termination_stats_hdr() { 3290 log_debug(gc, task, stats)("GC Termination Stats"); 3291 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 3292 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo"); 3293 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 3294 } 3295 3296 void G1CollectedHeap::print_termination_stats(uint worker_id, 3297 double elapsed_ms, 3298 double strong_roots_ms, 3299 double term_ms, 3300 size_t term_attempts, 3301 size_t alloc_buffer_waste, 3302 size_t undo_waste) const { 3303 log_debug(gc, task, stats) 3304 ("%3d %9.2f %9.2f %6.2f " 3305 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 3306 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 3307 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 3308 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 3309 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 3310 alloc_buffer_waste * HeapWordSize / K, 3311 undo_waste * HeapWordSize / K); 3312 } 3313 3314 class G1StringAndSymbolCleaningTask : public AbstractGangTask { 3315 private: 3316 BoolObjectClosure* _is_alive; 3317 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure; 3318 3319 int _initial_string_table_size; 3320 int _initial_symbol_table_size; 3321 3322 bool _process_strings; 3323 int _strings_processed; 3324 int _strings_removed; 3325 3326 bool _process_symbols; 3327 int _symbols_processed; 3328 int _symbols_removed; 3329 3330 bool _process_string_dedup; 3331 3332 public: 3333 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) : 3334 AbstractGangTask("String/Symbol Unlinking"), 3335 _is_alive(is_alive), 3336 _dedup_closure(is_alive, NULL, false), 3337 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 3338 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0), 3339 _process_string_dedup(process_string_dedup) { 3340 3341 _initial_string_table_size = StringTable::the_table()->table_size(); 3342 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 3343 if (process_strings) { 3344 StringTable::clear_parallel_claimed_index(); 3345 } 3346 if (process_symbols) { 3347 SymbolTable::clear_parallel_claimed_index(); 3348 } 3349 } 3350 3351 ~G1StringAndSymbolCleaningTask() { 3352 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 3353 "claim value %d after unlink less than initial string table size %d", 3354 StringTable::parallel_claimed_index(), _initial_string_table_size); 3355 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 3356 "claim value %d after unlink less than initial symbol table size %d", 3357 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size); 3358 3359 log_info(gc, stringtable)( 3360 "Cleaned string and symbol table, " 3361 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, " 3362 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed", 3363 strings_processed(), strings_removed(), 3364 symbols_processed(), symbols_removed()); 3365 } 3366 3367 void work(uint worker_id) { 3368 int strings_processed = 0; 3369 int strings_removed = 0; 3370 int symbols_processed = 0; 3371 int symbols_removed = 0; 3372 if (_process_strings) { 3373 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 3374 Atomic::add(strings_processed, &_strings_processed); 3375 Atomic::add(strings_removed, &_strings_removed); 3376 } 3377 if (_process_symbols) { 3378 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 3379 Atomic::add(symbols_processed, &_symbols_processed); 3380 Atomic::add(symbols_removed, &_symbols_removed); 3381 } 3382 if (_process_string_dedup) { 3383 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id); 3384 } 3385 } 3386 3387 size_t strings_processed() const { return (size_t)_strings_processed; } 3388 size_t strings_removed() const { return (size_t)_strings_removed; } 3389 3390 size_t symbols_processed() const { return (size_t)_symbols_processed; } 3391 size_t symbols_removed() const { return (size_t)_symbols_removed; } 3392 }; 3393 3394 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 3395 private: 3396 static Monitor* _lock; 3397 3398 BoolObjectClosure* const _is_alive; 3399 const bool _unloading_occurred; 3400 const uint _num_workers; 3401 3402 // Variables used to claim nmethods. 3403 CompiledMethod* _first_nmethod; 3404 CompiledMethod* volatile _claimed_nmethod; 3405 3406 // The list of nmethods that need to be processed by the second pass. 3407 CompiledMethod* volatile _postponed_list; 3408 volatile uint _num_entered_barrier; 3409 3410 public: 3411 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 3412 _is_alive(is_alive), 3413 _unloading_occurred(unloading_occurred), 3414 _num_workers(num_workers), 3415 _first_nmethod(NULL), 3416 _claimed_nmethod(NULL), 3417 _postponed_list(NULL), 3418 _num_entered_barrier(0) 3419 { 3420 CompiledMethod::increase_unloading_clock(); 3421 // Get first alive nmethod 3422 CompiledMethodIterator iter = CompiledMethodIterator(); 3423 if(iter.next_alive()) { 3424 _first_nmethod = iter.method(); 3425 } 3426 _claimed_nmethod = _first_nmethod; 3427 } 3428 3429 ~G1CodeCacheUnloadingTask() { 3430 CodeCache::verify_clean_inline_caches(); 3431 3432 CodeCache::set_needs_cache_clean(false); 3433 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 3434 3435 CodeCache::verify_icholder_relocations(); 3436 } 3437 3438 private: 3439 void add_to_postponed_list(CompiledMethod* nm) { 3440 CompiledMethod* old; 3441 do { 3442 old = _postponed_list; 3443 nm->set_unloading_next(old); 3444 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old); 3445 } 3446 3447 void clean_nmethod(CompiledMethod* nm) { 3448 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 3449 3450 if (postponed) { 3451 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 3452 add_to_postponed_list(nm); 3453 } 3454 3455 // Mark that this thread has been cleaned/unloaded. 3456 // After this call, it will be safe to ask if this nmethod was unloaded or not. 3457 nm->set_unloading_clock(CompiledMethod::global_unloading_clock()); 3458 } 3459 3460 void clean_nmethod_postponed(CompiledMethod* nm) { 3461 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 3462 } 3463 3464 static const int MaxClaimNmethods = 16; 3465 3466 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) { 3467 CompiledMethod* first; 3468 CompiledMethodIterator last; 3469 3470 do { 3471 *num_claimed_nmethods = 0; 3472 3473 first = _claimed_nmethod; 3474 last = CompiledMethodIterator(first); 3475 3476 if (first != NULL) { 3477 3478 for (int i = 0; i < MaxClaimNmethods; i++) { 3479 if (!last.next_alive()) { 3480 break; 3481 } 3482 claimed_nmethods[i] = last.method(); 3483 (*num_claimed_nmethods)++; 3484 } 3485 } 3486 3487 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first); 3488 } 3489 3490 CompiledMethod* claim_postponed_nmethod() { 3491 CompiledMethod* claim; 3492 CompiledMethod* next; 3493 3494 do { 3495 claim = _postponed_list; 3496 if (claim == NULL) { 3497 return NULL; 3498 } 3499 3500 next = claim->unloading_next(); 3501 3502 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim); 3503 3504 return claim; 3505 } 3506 3507 public: 3508 // Mark that we're done with the first pass of nmethod cleaning. 3509 void barrier_mark(uint worker_id) { 3510 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3511 _num_entered_barrier++; 3512 if (_num_entered_barrier == _num_workers) { 3513 ml.notify_all(); 3514 } 3515 } 3516 3517 // See if we have to wait for the other workers to 3518 // finish their first-pass nmethod cleaning work. 3519 void barrier_wait(uint worker_id) { 3520 if (_num_entered_barrier < _num_workers) { 3521 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3522 while (_num_entered_barrier < _num_workers) { 3523 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 3524 } 3525 } 3526 } 3527 3528 // Cleaning and unloading of nmethods. Some work has to be postponed 3529 // to the second pass, when we know which nmethods survive. 3530 void work_first_pass(uint worker_id) { 3531 // The first nmethods is claimed by the first worker. 3532 if (worker_id == 0 && _first_nmethod != NULL) { 3533 clean_nmethod(_first_nmethod); 3534 _first_nmethod = NULL; 3535 } 3536 3537 int num_claimed_nmethods; 3538 CompiledMethod* claimed_nmethods[MaxClaimNmethods]; 3539 3540 while (true) { 3541 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 3542 3543 if (num_claimed_nmethods == 0) { 3544 break; 3545 } 3546 3547 for (int i = 0; i < num_claimed_nmethods; i++) { 3548 clean_nmethod(claimed_nmethods[i]); 3549 } 3550 } 3551 } 3552 3553 void work_second_pass(uint worker_id) { 3554 CompiledMethod* nm; 3555 // Take care of postponed nmethods. 3556 while ((nm = claim_postponed_nmethod()) != NULL) { 3557 clean_nmethod_postponed(nm); 3558 } 3559 } 3560 }; 3561 3562 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 3563 3564 class G1KlassCleaningTask : public StackObj { 3565 BoolObjectClosure* _is_alive; 3566 volatile int _clean_klass_tree_claimed; 3567 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 3568 3569 public: 3570 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 3571 _is_alive(is_alive), 3572 _clean_klass_tree_claimed(0), 3573 _klass_iterator() { 3574 } 3575 3576 private: 3577 bool claim_clean_klass_tree_task() { 3578 if (_clean_klass_tree_claimed) { 3579 return false; 3580 } 3581 3582 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0; 3583 } 3584 3585 InstanceKlass* claim_next_klass() { 3586 Klass* klass; 3587 do { 3588 klass =_klass_iterator.next_klass(); 3589 } while (klass != NULL && !klass->is_instance_klass()); 3590 3591 // this can be null so don't call InstanceKlass::cast 3592 return static_cast<InstanceKlass*>(klass); 3593 } 3594 3595 public: 3596 3597 void clean_klass(InstanceKlass* ik) { 3598 ik->clean_weak_instanceklass_links(_is_alive); 3599 } 3600 3601 void work() { 3602 ResourceMark rm; 3603 3604 // One worker will clean the subklass/sibling klass tree. 3605 if (claim_clean_klass_tree_task()) { 3606 Klass::clean_subklass_tree(_is_alive); 3607 } 3608 3609 // All workers will help cleaning the classes, 3610 InstanceKlass* klass; 3611 while ((klass = claim_next_klass()) != NULL) { 3612 clean_klass(klass); 3613 } 3614 } 3615 }; 3616 3617 class G1ResolvedMethodCleaningTask : public StackObj { 3618 BoolObjectClosure* _is_alive; 3619 volatile int _resolved_method_task_claimed; 3620 public: 3621 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) : 3622 _is_alive(is_alive), _resolved_method_task_claimed(0) {} 3623 3624 bool claim_resolved_method_task() { 3625 if (_resolved_method_task_claimed) { 3626 return false; 3627 } 3628 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0; 3629 } 3630 3631 // These aren't big, one thread can do it all. 3632 void work() { 3633 if (claim_resolved_method_task()) { 3634 ResolvedMethodTable::unlink(_is_alive); 3635 } 3636 } 3637 }; 3638 3639 3640 // To minimize the remark pause times, the tasks below are done in parallel. 3641 class G1ParallelCleaningTask : public AbstractGangTask { 3642 private: 3643 G1StringAndSymbolCleaningTask _string_symbol_task; 3644 G1CodeCacheUnloadingTask _code_cache_task; 3645 G1KlassCleaningTask _klass_cleaning_task; 3646 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task; 3647 3648 public: 3649 // The constructor is run in the VMThread. 3650 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) : 3651 AbstractGangTask("Parallel Cleaning"), 3652 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()), 3653 _code_cache_task(num_workers, is_alive, unloading_occurred), 3654 _klass_cleaning_task(is_alive), 3655 _resolved_method_cleaning_task(is_alive) { 3656 } 3657 3658 // The parallel work done by all worker threads. 3659 void work(uint worker_id) { 3660 // Do first pass of code cache cleaning. 3661 _code_cache_task.work_first_pass(worker_id); 3662 3663 // Let the threads mark that the first pass is done. 3664 _code_cache_task.barrier_mark(worker_id); 3665 3666 // Clean the Strings and Symbols. 3667 _string_symbol_task.work(worker_id); 3668 3669 // Clean unreferenced things in the ResolvedMethodTable 3670 _resolved_method_cleaning_task.work(); 3671 3672 // Wait for all workers to finish the first code cache cleaning pass. 3673 _code_cache_task.barrier_wait(worker_id); 3674 3675 // Do the second code cache cleaning work, which realize on 3676 // the liveness information gathered during the first pass. 3677 _code_cache_task.work_second_pass(worker_id); 3678 3679 // Clean all klasses that were not unloaded. 3680 _klass_cleaning_task.work(); 3681 } 3682 }; 3683 3684 3685 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3686 bool class_unloading_occurred) { 3687 uint n_workers = workers()->active_workers(); 3688 3689 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred); 3690 workers()->run_task(&g1_unlink_task); 3691 } 3692 3693 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive, 3694 bool process_strings, 3695 bool process_symbols, 3696 bool process_string_dedup) { 3697 if (!process_strings && !process_symbols && !process_string_dedup) { 3698 // Nothing to clean. 3699 return; 3700 } 3701 3702 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup); 3703 workers()->run_task(&g1_unlink_task); 3704 3705 } 3706 3707 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3708 private: 3709 DirtyCardQueueSet* _queue; 3710 G1CollectedHeap* _g1h; 3711 public: 3712 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 3713 _queue(queue), _g1h(g1h) { } 3714 3715 virtual void work(uint worker_id) { 3716 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 3717 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 3718 3719 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3720 _queue->par_apply_closure_to_all_completed_buffers(&cl); 3721 3722 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3723 } 3724 }; 3725 3726 void G1CollectedHeap::redirty_logged_cards() { 3727 double redirty_logged_cards_start = os::elapsedTime(); 3728 3729 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 3730 dirty_card_queue_set().reset_for_par_iteration(); 3731 workers()->run_task(&redirty_task); 3732 3733 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 3734 dcq.merge_bufferlists(&dirty_card_queue_set()); 3735 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 3736 3737 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3738 } 3739 3740 // Weak Reference Processing support 3741 3742 // An always "is_alive" closure that is used to preserve referents. 3743 // If the object is non-null then it's alive. Used in the preservation 3744 // of referent objects that are pointed to by reference objects 3745 // discovered by the CM ref processor. 3746 class G1AlwaysAliveClosure: public BoolObjectClosure { 3747 G1CollectedHeap* _g1; 3748 public: 3749 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 3750 bool do_object_b(oop p) { 3751 if (p != NULL) { 3752 return true; 3753 } 3754 return false; 3755 } 3756 }; 3757 3758 bool G1STWIsAliveClosure::do_object_b(oop p) { 3759 // An object is reachable if it is outside the collection set, 3760 // or is inside and copied. 3761 return !_g1->is_in_cset(p) || p->is_forwarded(); 3762 } 3763 3764 // Non Copying Keep Alive closure 3765 class G1KeepAliveClosure: public OopClosure { 3766 G1CollectedHeap* _g1; 3767 public: 3768 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 3769 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3770 void do_oop(oop* p) { 3771 oop obj = *p; 3772 assert(obj != NULL, "the caller should have filtered out NULL values"); 3773 3774 const InCSetState cset_state = _g1->in_cset_state(obj); 3775 if (!cset_state.is_in_cset_or_humongous()) { 3776 return; 3777 } 3778 if (cset_state.is_in_cset()) { 3779 assert( obj->is_forwarded(), "invariant" ); 3780 *p = obj->forwardee(); 3781 } else { 3782 assert(!obj->is_forwarded(), "invariant" ); 3783 assert(cset_state.is_humongous(), 3784 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 3785 _g1->set_humongous_is_live(obj); 3786 } 3787 } 3788 }; 3789 3790 // Copying Keep Alive closure - can be called from both 3791 // serial and parallel code as long as different worker 3792 // threads utilize different G1ParScanThreadState instances 3793 // and different queues. 3794 3795 class G1CopyingKeepAliveClosure: public OopClosure { 3796 G1CollectedHeap* _g1h; 3797 OopClosure* _copy_non_heap_obj_cl; 3798 G1ParScanThreadState* _par_scan_state; 3799 3800 public: 3801 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3802 OopClosure* non_heap_obj_cl, 3803 G1ParScanThreadState* pss): 3804 _g1h(g1h), 3805 _copy_non_heap_obj_cl(non_heap_obj_cl), 3806 _par_scan_state(pss) 3807 {} 3808 3809 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3810 virtual void do_oop( oop* p) { do_oop_work(p); } 3811 3812 template <class T> void do_oop_work(T* p) { 3813 oop obj = oopDesc::load_decode_heap_oop(p); 3814 3815 if (_g1h->is_in_cset_or_humongous(obj)) { 3816 // If the referent object has been forwarded (either copied 3817 // to a new location or to itself in the event of an 3818 // evacuation failure) then we need to update the reference 3819 // field and, if both reference and referent are in the G1 3820 // heap, update the RSet for the referent. 3821 // 3822 // If the referent has not been forwarded then we have to keep 3823 // it alive by policy. Therefore we have copy the referent. 3824 // 3825 // If the reference field is in the G1 heap then we can push 3826 // on the PSS queue. When the queue is drained (after each 3827 // phase of reference processing) the object and it's followers 3828 // will be copied, the reference field set to point to the 3829 // new location, and the RSet updated. Otherwise we need to 3830 // use the the non-heap or metadata closures directly to copy 3831 // the referent object and update the pointer, while avoiding 3832 // updating the RSet. 3833 3834 if (_g1h->is_in_g1_reserved(p)) { 3835 _par_scan_state->push_on_queue(p); 3836 } else { 3837 assert(!Metaspace::contains((const void*)p), 3838 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)); 3839 _copy_non_heap_obj_cl->do_oop(p); 3840 } 3841 } 3842 } 3843 }; 3844 3845 // Serial drain queue closure. Called as the 'complete_gc' 3846 // closure for each discovered list in some of the 3847 // reference processing phases. 3848 3849 class G1STWDrainQueueClosure: public VoidClosure { 3850 protected: 3851 G1CollectedHeap* _g1h; 3852 G1ParScanThreadState* _par_scan_state; 3853 3854 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3855 3856 public: 3857 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3858 _g1h(g1h), 3859 _par_scan_state(pss) 3860 { } 3861 3862 void do_void() { 3863 G1ParScanThreadState* const pss = par_scan_state(); 3864 pss->trim_queue(); 3865 } 3866 }; 3867 3868 // Parallel Reference Processing closures 3869 3870 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3871 // processing during G1 evacuation pauses. 3872 3873 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3874 private: 3875 G1CollectedHeap* _g1h; 3876 G1ParScanThreadStateSet* _pss; 3877 RefToScanQueueSet* _queues; 3878 WorkGang* _workers; 3879 uint _active_workers; 3880 3881 public: 3882 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3883 G1ParScanThreadStateSet* per_thread_states, 3884 WorkGang* workers, 3885 RefToScanQueueSet *task_queues, 3886 uint n_workers) : 3887 _g1h(g1h), 3888 _pss(per_thread_states), 3889 _queues(task_queues), 3890 _workers(workers), 3891 _active_workers(n_workers) 3892 { 3893 g1h->ref_processor_stw()->set_active_mt_degree(n_workers); 3894 } 3895 3896 // Executes the given task using concurrent marking worker threads. 3897 virtual void execute(ProcessTask& task); 3898 virtual void execute(EnqueueTask& task); 3899 }; 3900 3901 // Gang task for possibly parallel reference processing 3902 3903 class G1STWRefProcTaskProxy: public AbstractGangTask { 3904 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3905 ProcessTask& _proc_task; 3906 G1CollectedHeap* _g1h; 3907 G1ParScanThreadStateSet* _pss; 3908 RefToScanQueueSet* _task_queues; 3909 ParallelTaskTerminator* _terminator; 3910 3911 public: 3912 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3913 G1CollectedHeap* g1h, 3914 G1ParScanThreadStateSet* per_thread_states, 3915 RefToScanQueueSet *task_queues, 3916 ParallelTaskTerminator* terminator) : 3917 AbstractGangTask("Process reference objects in parallel"), 3918 _proc_task(proc_task), 3919 _g1h(g1h), 3920 _pss(per_thread_states), 3921 _task_queues(task_queues), 3922 _terminator(terminator) 3923 {} 3924 3925 virtual void work(uint worker_id) { 3926 // The reference processing task executed by a single worker. 3927 ResourceMark rm; 3928 HandleMark hm; 3929 3930 G1STWIsAliveClosure is_alive(_g1h); 3931 3932 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3933 pss->set_ref_processor(NULL); 3934 3935 // Keep alive closure. 3936 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 3937 3938 // Complete GC closure 3939 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator); 3940 3941 // Call the reference processing task's work routine. 3942 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3943 3944 // Note we cannot assert that the refs array is empty here as not all 3945 // of the processing tasks (specifically phase2 - pp2_work) execute 3946 // the complete_gc closure (which ordinarily would drain the queue) so 3947 // the queue may not be empty. 3948 } 3949 }; 3950 3951 // Driver routine for parallel reference processing. 3952 // Creates an instance of the ref processing gang 3953 // task and has the worker threads execute it. 3954 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 3955 assert(_workers != NULL, "Need parallel worker threads."); 3956 3957 ParallelTaskTerminator terminator(_active_workers, _queues); 3958 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 3959 3960 _workers->run_task(&proc_task_proxy); 3961 } 3962 3963 // Gang task for parallel reference enqueueing. 3964 3965 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 3966 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 3967 EnqueueTask& _enq_task; 3968 3969 public: 3970 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 3971 AbstractGangTask("Enqueue reference objects in parallel"), 3972 _enq_task(enq_task) 3973 { } 3974 3975 virtual void work(uint worker_id) { 3976 _enq_task.work(worker_id); 3977 } 3978 }; 3979 3980 // Driver routine for parallel reference enqueueing. 3981 // Creates an instance of the ref enqueueing gang 3982 // task and has the worker threads execute it. 3983 3984 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 3985 assert(_workers != NULL, "Need parallel worker threads."); 3986 3987 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 3988 3989 _workers->run_task(&enq_task_proxy); 3990 } 3991 3992 // End of weak reference support closures 3993 3994 // Abstract task used to preserve (i.e. copy) any referent objects 3995 // that are in the collection set and are pointed to by reference 3996 // objects discovered by the CM ref processor. 3997 3998 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 3999 protected: 4000 G1CollectedHeap* _g1h; 4001 G1ParScanThreadStateSet* _pss; 4002 RefToScanQueueSet* _queues; 4003 ParallelTaskTerminator _terminator; 4004 uint _n_workers; 4005 4006 public: 4007 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) : 4008 AbstractGangTask("ParPreserveCMReferents"), 4009 _g1h(g1h), 4010 _pss(per_thread_states), 4011 _queues(task_queues), 4012 _terminator(workers, _queues), 4013 _n_workers(workers) 4014 { 4015 g1h->ref_processor_cm()->set_active_mt_degree(workers); 4016 } 4017 4018 void work(uint worker_id) { 4019 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id); 4020 4021 ResourceMark rm; 4022 HandleMark hm; 4023 4024 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4025 pss->set_ref_processor(NULL); 4026 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 4027 4028 // Is alive closure 4029 G1AlwaysAliveClosure always_alive(_g1h); 4030 4031 // Copying keep alive closure. Applied to referent objects that need 4032 // to be copied. 4033 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 4034 4035 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 4036 4037 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 4038 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 4039 4040 // limit is set using max_num_q() - which was set using ParallelGCThreads. 4041 // So this must be true - but assert just in case someone decides to 4042 // change the worker ids. 4043 assert(worker_id < limit, "sanity"); 4044 assert(!rp->discovery_is_atomic(), "check this code"); 4045 4046 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 4047 for (uint idx = worker_id; idx < limit; idx += stride) { 4048 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 4049 4050 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 4051 while (iter.has_next()) { 4052 // Since discovery is not atomic for the CM ref processor, we 4053 // can see some null referent objects. 4054 iter.load_ptrs(DEBUG_ONLY(true)); 4055 oop ref = iter.obj(); 4056 4057 // This will filter nulls. 4058 if (iter.is_referent_alive()) { 4059 iter.make_referent_alive(); 4060 } 4061 iter.move_to_next(); 4062 } 4063 } 4064 4065 // Drain the queue - which may cause stealing 4066 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator); 4067 drain_queue.do_void(); 4068 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 4069 assert(pss->queue_is_empty(), "should be"); 4070 } 4071 }; 4072 4073 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) { 4074 // Any reference objects, in the collection set, that were 'discovered' 4075 // by the CM ref processor should have already been copied (either by 4076 // applying the external root copy closure to the discovered lists, or 4077 // by following an RSet entry). 4078 // 4079 // But some of the referents, that are in the collection set, that these 4080 // reference objects point to may not have been copied: the STW ref 4081 // processor would have seen that the reference object had already 4082 // been 'discovered' and would have skipped discovering the reference, 4083 // but would not have treated the reference object as a regular oop. 4084 // As a result the copy closure would not have been applied to the 4085 // referent object. 4086 // 4087 // We need to explicitly copy these referent objects - the references 4088 // will be processed at the end of remarking. 4089 // 4090 // We also need to do this copying before we process the reference 4091 // objects discovered by the STW ref processor in case one of these 4092 // referents points to another object which is also referenced by an 4093 // object discovered by the STW ref processor. 4094 double preserve_cm_referents_time = 0.0; 4095 4096 // To avoid spawning task when there is no work to do, check that 4097 // a concurrent cycle is active and that some references have been 4098 // discovered. 4099 if (concurrent_mark()->cm_thread()->during_cycle() && 4100 ref_processor_cm()->has_discovered_references()) { 4101 double preserve_cm_referents_start = os::elapsedTime(); 4102 uint no_of_gc_workers = workers()->active_workers(); 4103 G1ParPreserveCMReferentsTask keep_cm_referents(this, 4104 per_thread_states, 4105 no_of_gc_workers, 4106 _task_queues); 4107 workers()->run_task(&keep_cm_referents); 4108 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start; 4109 } 4110 4111 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0); 4112 } 4113 4114 // Weak Reference processing during an evacuation pause (part 1). 4115 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 4116 double ref_proc_start = os::elapsedTime(); 4117 4118 ReferenceProcessor* rp = _ref_processor_stw; 4119 assert(rp->discovery_enabled(), "should have been enabled"); 4120 4121 // Closure to test whether a referent is alive. 4122 G1STWIsAliveClosure is_alive(this); 4123 4124 // Even when parallel reference processing is enabled, the processing 4125 // of JNI refs is serial and performed serially by the current thread 4126 // rather than by a worker. The following PSS will be used for processing 4127 // JNI refs. 4128 4129 // Use only a single queue for this PSS. 4130 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 4131 pss->set_ref_processor(NULL); 4132 assert(pss->queue_is_empty(), "pre-condition"); 4133 4134 // Keep alive closure. 4135 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss); 4136 4137 // Serial Complete GC closure 4138 G1STWDrainQueueClosure drain_queue(this, pss); 4139 4140 // Setup the soft refs policy... 4141 rp->setup_policy(false); 4142 4143 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times(); 4144 4145 ReferenceProcessorStats stats; 4146 if (!rp->processing_is_mt()) { 4147 // Serial reference processing... 4148 stats = rp->process_discovered_references(&is_alive, 4149 &keep_alive, 4150 &drain_queue, 4151 NULL, 4152 pt); 4153 } else { 4154 uint no_of_gc_workers = workers()->active_workers(); 4155 4156 // Parallel reference processing 4157 assert(no_of_gc_workers <= rp->max_num_q(), 4158 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 4159 no_of_gc_workers, rp->max_num_q()); 4160 4161 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers); 4162 stats = rp->process_discovered_references(&is_alive, 4163 &keep_alive, 4164 &drain_queue, 4165 &par_task_executor, 4166 pt); 4167 } 4168 4169 _gc_tracer_stw->report_gc_reference_stats(stats); 4170 4171 // We have completed copying any necessary live referent objects. 4172 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 4173 4174 double ref_proc_time = os::elapsedTime() - ref_proc_start; 4175 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 4176 } 4177 4178 // Weak Reference processing during an evacuation pause (part 2). 4179 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 4180 double ref_enq_start = os::elapsedTime(); 4181 4182 ReferenceProcessor* rp = _ref_processor_stw; 4183 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 4184 4185 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times(); 4186 4187 // Now enqueue any remaining on the discovered lists on to 4188 // the pending list. 4189 if (!rp->processing_is_mt()) { 4190 // Serial reference processing... 4191 rp->enqueue_discovered_references(NULL, pt); 4192 } else { 4193 // Parallel reference enqueueing 4194 4195 uint n_workers = workers()->active_workers(); 4196 4197 assert(n_workers <= rp->max_num_q(), 4198 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 4199 n_workers, rp->max_num_q()); 4200 4201 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers); 4202 rp->enqueue_discovered_references(&par_task_executor, pt); 4203 } 4204 4205 rp->verify_no_references_recorded(); 4206 assert(!rp->discovery_enabled(), "should have been disabled"); 4207 4208 // If during an initial mark pause we install a pending list head which is not otherwise reachable 4209 // ensure that it is marked in the bitmap for concurrent marking to discover. 4210 if (collector_state()->during_initial_mark_pause()) { 4211 oop pll_head = Universe::reference_pending_list(); 4212 if (pll_head != NULL) { 4213 _cm->mark_in_next_bitmap(pll_head); 4214 } 4215 } 4216 4217 // FIXME 4218 // CM's reference processing also cleans up the string and symbol tables. 4219 // Should we do that here also? We could, but it is a serial operation 4220 // and could significantly increase the pause time. 4221 4222 double ref_enq_time = os::elapsedTime() - ref_enq_start; 4223 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 4224 } 4225 4226 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 4227 double merge_pss_time_start = os::elapsedTime(); 4228 per_thread_states->flush(); 4229 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 4230 } 4231 4232 void G1CollectedHeap::pre_evacuate_collection_set() { 4233 _expand_heap_after_alloc_failure = true; 4234 _evacuation_failed = false; 4235 4236 // Disable the hot card cache. 4237 _hot_card_cache->reset_hot_cache_claimed_index(); 4238 _hot_card_cache->set_use_cache(false); 4239 4240 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 4241 _preserved_marks_set.assert_empty(); 4242 4243 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 4244 4245 // InitialMark needs claim bits to keep track of the marked-through CLDs. 4246 if (collector_state()->during_initial_mark_pause()) { 4247 double start_clear_claimed_marks = os::elapsedTime(); 4248 4249 ClassLoaderDataGraph::clear_claimed_marks(); 4250 4251 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 4252 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 4253 } 4254 } 4255 4256 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) { 4257 // Should G1EvacuationFailureALot be in effect for this GC? 4258 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 4259 4260 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 4261 4262 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 4263 4264 double start_par_time_sec = os::elapsedTime(); 4265 double end_par_time_sec; 4266 4267 { 4268 const uint n_workers = workers()->active_workers(); 4269 G1RootProcessor root_processor(this, n_workers); 4270 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 4271 4272 print_termination_stats_hdr(); 4273 4274 workers()->run_task(&g1_par_task); 4275 end_par_time_sec = os::elapsedTime(); 4276 4277 // Closing the inner scope will execute the destructor 4278 // for the G1RootProcessor object. We record the current 4279 // elapsed time before closing the scope so that time 4280 // taken for the destructor is NOT included in the 4281 // reported parallel time. 4282 } 4283 4284 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 4285 phase_times->record_par_time(par_time_ms); 4286 4287 double code_root_fixup_time_ms = 4288 (os::elapsedTime() - end_par_time_sec) * 1000.0; 4289 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 4290 } 4291 4292 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 4293 // Process any discovered reference objects - we have 4294 // to do this _before_ we retire the GC alloc regions 4295 // as we may have to copy some 'reachable' referent 4296 // objects (and their reachable sub-graphs) that were 4297 // not copied during the pause. 4298 if (g1_policy()->should_process_references()) { 4299 preserve_cm_referents(per_thread_states); 4300 process_discovered_references(per_thread_states); 4301 } else { 4302 ref_processor_stw()->verify_no_references_recorded(); 4303 } 4304 4305 G1STWIsAliveClosure is_alive(this); 4306 G1KeepAliveClosure keep_alive(this); 4307 4308 { 4309 double start = os::elapsedTime(); 4310 4311 WeakProcessor::weak_oops_do(&is_alive, &keep_alive); 4312 4313 double time_ms = (os::elapsedTime() - start) * 1000.0; 4314 g1_policy()->phase_times()->record_ref_proc_time(time_ms); 4315 } 4316 4317 if (G1StringDedup::is_enabled()) { 4318 double fixup_start = os::elapsedTime(); 4319 4320 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times()); 4321 4322 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 4323 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms); 4324 } 4325 4326 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 4327 4328 if (evacuation_failed()) { 4329 restore_after_evac_failure(); 4330 4331 // Reset the G1EvacuationFailureALot counters and flags 4332 // Note: the values are reset only when an actual 4333 // evacuation failure occurs. 4334 NOT_PRODUCT(reset_evacuation_should_fail();) 4335 } 4336 4337 _preserved_marks_set.assert_empty(); 4338 4339 // Enqueue any remaining references remaining on the STW 4340 // reference processor's discovered lists. We need to do 4341 // this after the card table is cleaned (and verified) as 4342 // the act of enqueueing entries on to the pending list 4343 // will log these updates (and dirty their associated 4344 // cards). We need these updates logged to update any 4345 // RSets. 4346 if (g1_policy()->should_process_references()) { 4347 enqueue_discovered_references(per_thread_states); 4348 } else { 4349 g1_policy()->phase_times()->record_ref_enq_time(0); 4350 } 4351 4352 _allocator->release_gc_alloc_regions(evacuation_info); 4353 4354 merge_per_thread_state_info(per_thread_states); 4355 4356 // Reset and re-enable the hot card cache. 4357 // Note the counts for the cards in the regions in the 4358 // collection set are reset when the collection set is freed. 4359 _hot_card_cache->reset_hot_cache(); 4360 _hot_card_cache->set_use_cache(true); 4361 4362 purge_code_root_memory(); 4363 4364 redirty_logged_cards(); 4365 #if COMPILER2_OR_JVMCI 4366 double start = os::elapsedTime(); 4367 DerivedPointerTable::update_pointers(); 4368 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 4369 #endif 4370 g1_policy()->print_age_table(); 4371 } 4372 4373 void G1CollectedHeap::record_obj_copy_mem_stats() { 4374 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 4375 4376 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 4377 create_g1_evac_summary(&_old_evac_stats)); 4378 } 4379 4380 void G1CollectedHeap::free_region(HeapRegion* hr, 4381 FreeRegionList* free_list, 4382 bool skip_remset, 4383 bool skip_hot_card_cache, 4384 bool locked) { 4385 assert(!hr->is_free(), "the region should not be free"); 4386 assert(!hr->is_empty(), "the region should not be empty"); 4387 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 4388 assert(free_list != NULL, "pre-condition"); 4389 4390 if (G1VerifyBitmaps) { 4391 MemRegion mr(hr->bottom(), hr->end()); 4392 concurrent_mark()->clear_range_in_prev_bitmap(mr); 4393 } 4394 4395 // Clear the card counts for this region. 4396 // Note: we only need to do this if the region is not young 4397 // (since we don't refine cards in young regions). 4398 if (!skip_hot_card_cache && !hr->is_young()) { 4399 _hot_card_cache->reset_card_counts(hr); 4400 } 4401 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 4402 free_list->add_ordered(hr); 4403 } 4404 4405 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4406 FreeRegionList* free_list, 4407 bool skip_remset) { 4408 assert(hr->is_humongous(), "this is only for humongous regions"); 4409 assert(free_list != NULL, "pre-condition"); 4410 hr->clear_humongous(); 4411 free_region(hr, free_list, skip_remset); 4412 } 4413 4414 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 4415 const uint humongous_regions_removed) { 4416 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 4417 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4418 _old_set.bulk_remove(old_regions_removed); 4419 _humongous_set.bulk_remove(humongous_regions_removed); 4420 } 4421 4422 } 4423 4424 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4425 assert(list != NULL, "list can't be null"); 4426 if (!list->is_empty()) { 4427 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4428 _hrm.insert_list_into_free_list(list); 4429 } 4430 } 4431 4432 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4433 decrease_used(bytes); 4434 } 4435 4436 class G1ParScrubRemSetTask: public AbstractGangTask { 4437 protected: 4438 G1RemSet* _g1rs; 4439 HeapRegionClaimer _hrclaimer; 4440 4441 public: 4442 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) : 4443 AbstractGangTask("G1 ScrubRS"), 4444 _g1rs(g1_rs), 4445 _hrclaimer(num_workers) { 4446 } 4447 4448 void work(uint worker_id) { 4449 _g1rs->scrub(worker_id, &_hrclaimer); 4450 } 4451 }; 4452 4453 void G1CollectedHeap::scrub_rem_set() { 4454 uint num_workers = workers()->active_workers(); 4455 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers); 4456 workers()->run_task(&g1_par_scrub_rs_task); 4457 } 4458 4459 class G1FreeCollectionSetTask : public AbstractGangTask { 4460 private: 4461 4462 // Closure applied to all regions in the collection set to do work that needs to 4463 // be done serially in a single thread. 4464 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 4465 private: 4466 EvacuationInfo* _evacuation_info; 4467 const size_t* _surviving_young_words; 4468 4469 // Bytes used in successfully evacuated regions before the evacuation. 4470 size_t _before_used_bytes; 4471 // Bytes used in unsucessfully evacuated regions before the evacuation 4472 size_t _after_used_bytes; 4473 4474 size_t _bytes_allocated_in_old_since_last_gc; 4475 4476 size_t _failure_used_words; 4477 size_t _failure_waste_words; 4478 4479 FreeRegionList _local_free_list; 4480 public: 4481 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4482 HeapRegionClosure(), 4483 _evacuation_info(evacuation_info), 4484 _surviving_young_words(surviving_young_words), 4485 _before_used_bytes(0), 4486 _after_used_bytes(0), 4487 _bytes_allocated_in_old_since_last_gc(0), 4488 _failure_used_words(0), 4489 _failure_waste_words(0), 4490 _local_free_list("Local Region List for CSet Freeing") { 4491 } 4492 4493 virtual bool do_heap_region(HeapRegion* r) { 4494 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4495 4496 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 4497 g1h->clear_in_cset(r); 4498 4499 if (r->is_young()) { 4500 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(), 4501 "Young index %d is wrong for region %u of type %s with %u young regions", 4502 r->young_index_in_cset(), 4503 r->hrm_index(), 4504 r->get_type_str(), 4505 g1h->collection_set()->young_region_length()); 4506 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 4507 r->record_surv_words_in_group(words_survived); 4508 } 4509 4510 if (!r->evacuation_failed()) { 4511 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4512 _before_used_bytes += r->used(); 4513 g1h->free_region(r, 4514 &_local_free_list, 4515 true, /* skip_remset */ 4516 true, /* skip_hot_card_cache */ 4517 true /* locked */); 4518 } else { 4519 r->uninstall_surv_rate_group(); 4520 r->set_young_index_in_cset(-1); 4521 r->set_evacuation_failed(false); 4522 // When moving a young gen region to old gen, we "allocate" that whole region 4523 // there. This is in addition to any already evacuated objects. Notify the 4524 // policy about that. 4525 // Old gen regions do not cause an additional allocation: both the objects 4526 // still in the region and the ones already moved are accounted for elsewhere. 4527 if (r->is_young()) { 4528 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4529 } 4530 // The region is now considered to be old. 4531 r->set_old(); 4532 // Do some allocation statistics accounting. Regions that failed evacuation 4533 // are always made old, so there is no need to update anything in the young 4534 // gen statistics, but we need to update old gen statistics. 4535 size_t used_words = r->marked_bytes() / HeapWordSize; 4536 4537 _failure_used_words += used_words; 4538 _failure_waste_words += HeapRegion::GrainWords - used_words; 4539 4540 g1h->old_set_add(r); 4541 _after_used_bytes += r->used(); 4542 } 4543 return false; 4544 } 4545 4546 void complete_work() { 4547 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4548 4549 _evacuation_info->set_regions_freed(_local_free_list.length()); 4550 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4551 4552 g1h->prepend_to_freelist(&_local_free_list); 4553 g1h->decrement_summary_bytes(_before_used_bytes); 4554 4555 G1Policy* policy = g1h->g1_policy(); 4556 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4557 4558 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4559 } 4560 }; 4561 4562 G1CollectionSet* _collection_set; 4563 G1SerialFreeCollectionSetClosure _cl; 4564 const size_t* _surviving_young_words; 4565 4566 size_t _rs_lengths; 4567 4568 volatile jint _serial_work_claim; 4569 4570 struct WorkItem { 4571 uint region_idx; 4572 bool is_young; 4573 bool evacuation_failed; 4574 4575 WorkItem(HeapRegion* r) { 4576 region_idx = r->hrm_index(); 4577 is_young = r->is_young(); 4578 evacuation_failed = r->evacuation_failed(); 4579 } 4580 }; 4581 4582 volatile size_t _parallel_work_claim; 4583 size_t _num_work_items; 4584 WorkItem* _work_items; 4585 4586 void do_serial_work() { 4587 // Need to grab the lock to be allowed to modify the old region list. 4588 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4589 _collection_set->iterate(&_cl); 4590 } 4591 4592 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4593 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4594 4595 HeapRegion* r = g1h->region_at(region_idx); 4596 assert(!g1h->is_on_master_free_list(r), "sanity"); 4597 4598 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths); 4599 4600 if (!is_young) { 4601 g1h->_hot_card_cache->reset_card_counts(r); 4602 } 4603 4604 if (!evacuation_failed) { 4605 r->rem_set()->clear_locked(); 4606 } 4607 } 4608 4609 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4610 private: 4611 size_t _cur_idx; 4612 WorkItem* _work_items; 4613 public: 4614 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4615 4616 virtual bool do_heap_region(HeapRegion* r) { 4617 _work_items[_cur_idx++] = WorkItem(r); 4618 return false; 4619 } 4620 }; 4621 4622 void prepare_work() { 4623 G1PrepareFreeCollectionSetClosure cl(_work_items); 4624 _collection_set->iterate(&cl); 4625 } 4626 4627 void complete_work() { 4628 _cl.complete_work(); 4629 4630 G1Policy* policy = G1CollectedHeap::heap()->g1_policy(); 4631 policy->record_max_rs_lengths(_rs_lengths); 4632 policy->cset_regions_freed(); 4633 } 4634 public: 4635 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4636 AbstractGangTask("G1 Free Collection Set"), 4637 _cl(evacuation_info, surviving_young_words), 4638 _collection_set(collection_set), 4639 _surviving_young_words(surviving_young_words), 4640 _serial_work_claim(0), 4641 _rs_lengths(0), 4642 _parallel_work_claim(0), 4643 _num_work_items(collection_set->region_length()), 4644 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4645 prepare_work(); 4646 } 4647 4648 ~G1FreeCollectionSetTask() { 4649 complete_work(); 4650 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4651 } 4652 4653 // Chunk size for work distribution. The chosen value has been determined experimentally 4654 // to be a good tradeoff between overhead and achievable parallelism. 4655 static uint chunk_size() { return 32; } 4656 4657 virtual void work(uint worker_id) { 4658 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4659 4660 // Claim serial work. 4661 if (_serial_work_claim == 0) { 4662 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4663 if (value == 0) { 4664 double serial_time = os::elapsedTime(); 4665 do_serial_work(); 4666 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4667 } 4668 } 4669 4670 // Start parallel work. 4671 double young_time = 0.0; 4672 bool has_young_time = false; 4673 double non_young_time = 0.0; 4674 bool has_non_young_time = false; 4675 4676 while (true) { 4677 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4678 size_t cur = end - chunk_size(); 4679 4680 if (cur >= _num_work_items) { 4681 break; 4682 } 4683 4684 double start_time = os::elapsedTime(); 4685 4686 end = MIN2(end, _num_work_items); 4687 4688 for (; cur < end; cur++) { 4689 bool is_young = _work_items[cur].is_young; 4690 4691 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4692 4693 double end_time = os::elapsedTime(); 4694 double time_taken = end_time - start_time; 4695 if (is_young) { 4696 young_time += time_taken; 4697 has_young_time = true; 4698 } else { 4699 non_young_time += time_taken; 4700 has_non_young_time = true; 4701 } 4702 start_time = end_time; 4703 } 4704 } 4705 4706 if (has_young_time) { 4707 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4708 } 4709 if (has_non_young_time) { 4710 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4711 } 4712 } 4713 }; 4714 4715 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4716 _eden.clear(); 4717 4718 double free_cset_start_time = os::elapsedTime(); 4719 4720 { 4721 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U); 4722 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4723 4724 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4725 4726 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4727 cl.name(), 4728 num_workers, 4729 _collection_set.region_length()); 4730 workers()->run_task(&cl, num_workers); 4731 } 4732 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4733 4734 collection_set->clear(); 4735 } 4736 4737 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4738 private: 4739 FreeRegionList* _free_region_list; 4740 HeapRegionSet* _proxy_set; 4741 uint _humongous_objects_reclaimed; 4742 uint _humongous_regions_reclaimed; 4743 size_t _freed_bytes; 4744 public: 4745 4746 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4747 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4748 } 4749 4750 virtual bool do_heap_region(HeapRegion* r) { 4751 if (!r->is_starts_humongous()) { 4752 return false; 4753 } 4754 4755 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4756 4757 oop obj = (oop)r->bottom(); 4758 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4759 4760 // The following checks whether the humongous object is live are sufficient. 4761 // The main additional check (in addition to having a reference from the roots 4762 // or the young gen) is whether the humongous object has a remembered set entry. 4763 // 4764 // A humongous object cannot be live if there is no remembered set for it 4765 // because: 4766 // - there can be no references from within humongous starts regions referencing 4767 // the object because we never allocate other objects into them. 4768 // (I.e. there are no intra-region references that may be missed by the 4769 // remembered set) 4770 // - as soon there is a remembered set entry to the humongous starts region 4771 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4772 // until the end of a concurrent mark. 4773 // 4774 // It is not required to check whether the object has been found dead by marking 4775 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4776 // all objects allocated during that time are considered live. 4777 // SATB marking is even more conservative than the remembered set. 4778 // So if at this point in the collection there is no remembered set entry, 4779 // nobody has a reference to it. 4780 // At the start of collection we flush all refinement logs, and remembered sets 4781 // are completely up-to-date wrt to references to the humongous object. 4782 // 4783 // Other implementation considerations: 4784 // - never consider object arrays at this time because they would pose 4785 // considerable effort for cleaning up the the remembered sets. This is 4786 // required because stale remembered sets might reference locations that 4787 // are currently allocated into. 4788 uint region_idx = r->hrm_index(); 4789 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4790 !r->rem_set()->is_empty()) { 4791 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", 4792 region_idx, 4793 (size_t)obj->size() * HeapWordSize, 4794 p2i(r->bottom()), 4795 r->rem_set()->occupied(), 4796 r->rem_set()->strong_code_roots_list_length(), 4797 next_bitmap->is_marked(r->bottom()), 4798 g1h->is_humongous_reclaim_candidate(region_idx), 4799 obj->is_typeArray() 4800 ); 4801 return false; 4802 } 4803 4804 guarantee(obj->is_typeArray(), 4805 "Only eagerly reclaiming type arrays is supported, but the object " 4806 PTR_FORMAT " is not.", p2i(r->bottom())); 4807 4808 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", 4809 region_idx, 4810 (size_t)obj->size() * HeapWordSize, 4811 p2i(r->bottom()), 4812 r->rem_set()->occupied(), 4813 r->rem_set()->strong_code_roots_list_length(), 4814 next_bitmap->is_marked(r->bottom()), 4815 g1h->is_humongous_reclaim_candidate(region_idx), 4816 obj->is_typeArray() 4817 ); 4818 4819 // Need to clear mark bit of the humongous object if already set. 4820 if (next_bitmap->is_marked(r->bottom())) { 4821 next_bitmap->clear(r->bottom()); 4822 } 4823 _humongous_objects_reclaimed++; 4824 do { 4825 HeapRegion* next = g1h->next_region_in_humongous(r); 4826 _freed_bytes += r->used(); 4827 r->set_containing_set(NULL); 4828 _humongous_regions_reclaimed++; 4829 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ ); 4830 r = next; 4831 } while (r != NULL); 4832 4833 return false; 4834 } 4835 4836 uint humongous_objects_reclaimed() { 4837 return _humongous_objects_reclaimed; 4838 } 4839 4840 uint humongous_regions_reclaimed() { 4841 return _humongous_regions_reclaimed; 4842 } 4843 4844 size_t bytes_freed() const { 4845 return _freed_bytes; 4846 } 4847 }; 4848 4849 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4850 assert_at_safepoint_on_vm_thread(); 4851 4852 if (!G1EagerReclaimHumongousObjects || 4853 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4854 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4855 return; 4856 } 4857 4858 double start_time = os::elapsedTime(); 4859 4860 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4861 4862 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4863 heap_region_iterate(&cl); 4864 4865 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4866 4867 G1HRPrinter* hrp = hr_printer(); 4868 if (hrp->is_active()) { 4869 FreeRegionListIterator iter(&local_cleanup_list); 4870 while (iter.more_available()) { 4871 HeapRegion* hr = iter.get_next(); 4872 hrp->cleanup(hr); 4873 } 4874 } 4875 4876 prepend_to_freelist(&local_cleanup_list); 4877 decrement_summary_bytes(cl.bytes_freed()); 4878 4879 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4880 cl.humongous_objects_reclaimed()); 4881 } 4882 4883 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4884 public: 4885 virtual bool do_heap_region(HeapRegion* r) { 4886 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4887 G1CollectedHeap::heap()->clear_in_cset(r); 4888 r->set_young_index_in_cset(-1); 4889 return false; 4890 } 4891 }; 4892 4893 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4894 G1AbandonCollectionSetClosure cl; 4895 collection_set->iterate(&cl); 4896 4897 collection_set->clear(); 4898 collection_set->stop_incremental_building(); 4899 } 4900 4901 void G1CollectedHeap::set_free_regions_coming() { 4902 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming"); 4903 4904 assert(!free_regions_coming(), "pre-condition"); 4905 _free_regions_coming = true; 4906 } 4907 4908 void G1CollectedHeap::reset_free_regions_coming() { 4909 assert(free_regions_coming(), "pre-condition"); 4910 4911 { 4912 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 4913 _free_regions_coming = false; 4914 SecondaryFreeList_lock->notify_all(); 4915 } 4916 4917 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming"); 4918 } 4919 4920 void G1CollectedHeap::wait_while_free_regions_coming() { 4921 // Most of the time we won't have to wait, so let's do a quick test 4922 // first before we take the lock. 4923 if (!free_regions_coming()) { 4924 return; 4925 } 4926 4927 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions"); 4928 4929 { 4930 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 4931 while (free_regions_coming()) { 4932 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 4933 } 4934 } 4935 4936 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions"); 4937 } 4938 4939 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4940 return _allocator->is_retained_old_region(hr); 4941 } 4942 4943 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4944 _eden.add(hr); 4945 _g1_policy->set_region_eden(hr); 4946 } 4947 4948 #ifdef ASSERT 4949 4950 class NoYoungRegionsClosure: public HeapRegionClosure { 4951 private: 4952 bool _success; 4953 public: 4954 NoYoungRegionsClosure() : _success(true) { } 4955 bool do_heap_region(HeapRegion* r) { 4956 if (r->is_young()) { 4957 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4958 p2i(r->bottom()), p2i(r->end())); 4959 _success = false; 4960 } 4961 return false; 4962 } 4963 bool success() { return _success; } 4964 }; 4965 4966 bool G1CollectedHeap::check_young_list_empty() { 4967 bool ret = (young_regions_count() == 0); 4968 4969 NoYoungRegionsClosure closure; 4970 heap_region_iterate(&closure); 4971 ret = ret && closure.success(); 4972 4973 return ret; 4974 } 4975 4976 #endif // ASSERT 4977 4978 class TearDownRegionSetsClosure : public HeapRegionClosure { 4979 private: 4980 HeapRegionSet *_old_set; 4981 4982 public: 4983 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4984 4985 bool do_heap_region(HeapRegion* r) { 4986 if (r->is_old()) { 4987 _old_set->remove(r); 4988 } else if(r->is_young()) { 4989 r->uninstall_surv_rate_group(); 4990 } else { 4991 // We ignore free regions, we'll empty the free list afterwards. 4992 // We ignore humongous regions, we're not tearing down the 4993 // humongous regions set. 4994 assert(r->is_free() || r->is_humongous(), 4995 "it cannot be another type"); 4996 } 4997 return false; 4998 } 4999 5000 ~TearDownRegionSetsClosure() { 5001 assert(_old_set->is_empty(), "post-condition"); 5002 } 5003 }; 5004 5005 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 5006 assert_at_safepoint_on_vm_thread(); 5007 5008 if (!free_list_only) { 5009 TearDownRegionSetsClosure cl(&_old_set); 5010 heap_region_iterate(&cl); 5011 5012 // Note that emptying the _young_list is postponed and instead done as 5013 // the first step when rebuilding the regions sets again. The reason for 5014 // this is that during a full GC string deduplication needs to know if 5015 // a collected region was young or old when the full GC was initiated. 5016 } 5017 _hrm.remove_all_free_regions(); 5018 } 5019 5020 void G1CollectedHeap::increase_used(size_t bytes) { 5021 _summary_bytes_used += bytes; 5022 } 5023 5024 void G1CollectedHeap::decrease_used(size_t bytes) { 5025 assert(_summary_bytes_used >= bytes, 5026 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 5027 _summary_bytes_used, bytes); 5028 _summary_bytes_used -= bytes; 5029 } 5030 5031 void G1CollectedHeap::set_used(size_t bytes) { 5032 _summary_bytes_used = bytes; 5033 } 5034 5035 class RebuildRegionSetsClosure : public HeapRegionClosure { 5036 private: 5037 bool _free_list_only; 5038 HeapRegionSet* _old_set; 5039 HeapRegionManager* _hrm; 5040 size_t _total_used; 5041 5042 public: 5043 RebuildRegionSetsClosure(bool free_list_only, 5044 HeapRegionSet* old_set, HeapRegionManager* hrm) : 5045 _free_list_only(free_list_only), 5046 _old_set(old_set), _hrm(hrm), _total_used(0) { 5047 assert(_hrm->num_free_regions() == 0, "pre-condition"); 5048 if (!free_list_only) { 5049 assert(_old_set->is_empty(), "pre-condition"); 5050 } 5051 } 5052 5053 bool do_heap_region(HeapRegion* r) { 5054 if (r->is_empty()) { 5055 // Add free regions to the free list 5056 r->set_free(); 5057 _hrm->insert_into_free_list(r); 5058 } else if (!_free_list_only) { 5059 5060 if (r->is_humongous()) { 5061 // We ignore humongous regions. We left the humongous set unchanged. 5062 } else { 5063 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 5064 // We now move all (non-humongous, non-old) regions to old gen, and register them as such. 5065 r->move_to_old(); 5066 _old_set->add(r); 5067 } 5068 _total_used += r->used(); 5069 } 5070 5071 return false; 5072 } 5073 5074 size_t total_used() { 5075 return _total_used; 5076 } 5077 }; 5078 5079 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 5080 assert_at_safepoint_on_vm_thread(); 5081 5082 if (!free_list_only) { 5083 _eden.clear(); 5084 _survivor.clear(); 5085 } 5086 5087 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 5088 heap_region_iterate(&cl); 5089 5090 if (!free_list_only) { 5091 set_used(cl.total_used()); 5092 if (_archive_allocator != NULL) { 5093 _archive_allocator->clear_used(); 5094 } 5095 } 5096 assert(used_unlocked() == recalculate_used(), 5097 "inconsistent used_unlocked(), " 5098 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 5099 used_unlocked(), recalculate_used()); 5100 } 5101 5102 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 5103 HeapRegion* hr = heap_region_containing(p); 5104 return hr->is_in(p); 5105 } 5106 5107 // Methods for the mutator alloc region 5108 5109 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 5110 bool force) { 5111 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 5112 bool should_allocate = g1_policy()->should_allocate_mutator_region(); 5113 if (force || should_allocate) { 5114 HeapRegion* new_alloc_region = new_region(word_size, 5115 false /* is_old */, 5116 false /* do_expand */); 5117 if (new_alloc_region != NULL) { 5118 set_region_short_lived_locked(new_alloc_region); 5119 _hr_printer.alloc(new_alloc_region, !should_allocate); 5120 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 5121 return new_alloc_region; 5122 } 5123 } 5124 return NULL; 5125 } 5126 5127 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 5128 size_t allocated_bytes) { 5129 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 5130 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 5131 5132 collection_set()->add_eden_region(alloc_region); 5133 increase_used(allocated_bytes); 5134 _hr_printer.retire(alloc_region); 5135 // We update the eden sizes here, when the region is retired, 5136 // instead of when it's allocated, since this is the point that its 5137 // used space has been recored in _summary_bytes_used. 5138 g1mm()->update_eden_size(); 5139 } 5140 5141 // Methods for the GC alloc regions 5142 5143 bool G1CollectedHeap::has_more_regions(InCSetState dest) { 5144 if (dest.is_old()) { 5145 return true; 5146 } else { 5147 return survivor_regions_count() < g1_policy()->max_survivor_regions(); 5148 } 5149 } 5150 5151 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) { 5152 assert(FreeList_lock->owned_by_self(), "pre-condition"); 5153 5154 if (!has_more_regions(dest)) { 5155 return NULL; 5156 } 5157 5158 const bool is_survivor = dest.is_young(); 5159 5160 HeapRegion* new_alloc_region = new_region(word_size, 5161 !is_survivor, 5162 true /* do_expand */); 5163 if (new_alloc_region != NULL) { 5164 // We really only need to do this for old regions given that we 5165 // should never scan survivors. But it doesn't hurt to do it 5166 // for survivors too. 5167 new_alloc_region->record_timestamp(); 5168 if (is_survivor) { 5169 new_alloc_region->set_survivor(); 5170 _survivor.add(new_alloc_region); 5171 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 5172 } else { 5173 new_alloc_region->set_old(); 5174 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 5175 } 5176 _hr_printer.alloc(new_alloc_region); 5177 bool during_im = collector_state()->during_initial_mark_pause(); 5178 new_alloc_region->note_start_of_copying(during_im); 5179 return new_alloc_region; 5180 } 5181 return NULL; 5182 } 5183 5184 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 5185 size_t allocated_bytes, 5186 InCSetState dest) { 5187 bool during_im = collector_state()->during_initial_mark_pause(); 5188 alloc_region->note_end_of_copying(during_im); 5189 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 5190 if (dest.is_old()) { 5191 _old_set.add(alloc_region); 5192 } 5193 _hr_printer.retire(alloc_region); 5194 } 5195 5196 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 5197 bool expanded = false; 5198 uint index = _hrm.find_highest_free(&expanded); 5199 5200 if (index != G1_NO_HRM_INDEX) { 5201 if (expanded) { 5202 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 5203 HeapRegion::GrainWords * HeapWordSize); 5204 } 5205 _hrm.allocate_free_regions_starting_at(index, 1); 5206 return region_at(index); 5207 } 5208 return NULL; 5209 } 5210 5211 // Optimized nmethod scanning 5212 5213 class RegisterNMethodOopClosure: public OopClosure { 5214 G1CollectedHeap* _g1h; 5215 nmethod* _nm; 5216 5217 template <class T> void do_oop_work(T* p) { 5218 T heap_oop = oopDesc::load_heap_oop(p); 5219 if (!oopDesc::is_null(heap_oop)) { 5220 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 5221 HeapRegion* hr = _g1h->heap_region_containing(obj); 5222 assert(!hr->is_continues_humongous(), 5223 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 5224 " starting at " HR_FORMAT, 5225 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 5226 5227 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 5228 hr->add_strong_code_root_locked(_nm); 5229 } 5230 } 5231 5232 public: 5233 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 5234 _g1h(g1h), _nm(nm) {} 5235 5236 void do_oop(oop* p) { do_oop_work(p); } 5237 void do_oop(narrowOop* p) { do_oop_work(p); } 5238 }; 5239 5240 class UnregisterNMethodOopClosure: public OopClosure { 5241 G1CollectedHeap* _g1h; 5242 nmethod* _nm; 5243 5244 template <class T> void do_oop_work(T* p) { 5245 T heap_oop = oopDesc::load_heap_oop(p); 5246 if (!oopDesc::is_null(heap_oop)) { 5247 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 5248 HeapRegion* hr = _g1h->heap_region_containing(obj); 5249 assert(!hr->is_continues_humongous(), 5250 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 5251 " starting at " HR_FORMAT, 5252 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 5253 5254 hr->remove_strong_code_root(_nm); 5255 } 5256 } 5257 5258 public: 5259 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 5260 _g1h(g1h), _nm(nm) {} 5261 5262 void do_oop(oop* p) { do_oop_work(p); } 5263 void do_oop(narrowOop* p) { do_oop_work(p); } 5264 }; 5265 5266 // Returns true if the reference points to an object that 5267 // can move in an incremental collection. 5268 bool G1CollectedHeap::is_scavengable(oop obj) { 5269 HeapRegion* hr = heap_region_containing(obj); 5270 return !hr->is_pinned(); 5271 } 5272 5273 void G1CollectedHeap::register_nmethod(nmethod* nm) { 5274 guarantee(nm != NULL, "sanity"); 5275 RegisterNMethodOopClosure reg_cl(this, nm); 5276 nm->oops_do(®_cl); 5277 } 5278 5279 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 5280 guarantee(nm != NULL, "sanity"); 5281 UnregisterNMethodOopClosure reg_cl(this, nm); 5282 nm->oops_do(®_cl, true); 5283 } 5284 5285 void G1CollectedHeap::purge_code_root_memory() { 5286 double purge_start = os::elapsedTime(); 5287 G1CodeRootSet::purge(); 5288 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 5289 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 5290 } 5291 5292 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 5293 G1CollectedHeap* _g1h; 5294 5295 public: 5296 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 5297 _g1h(g1h) {} 5298 5299 void do_code_blob(CodeBlob* cb) { 5300 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 5301 if (nm == NULL) { 5302 return; 5303 } 5304 5305 if (ScavengeRootsInCode) { 5306 _g1h->register_nmethod(nm); 5307 } 5308 } 5309 }; 5310 5311 void G1CollectedHeap::rebuild_strong_code_roots() { 5312 RebuildStrongCodeRootClosure blob_cl(this); 5313 CodeCache::blobs_do(&blob_cl); 5314 } 5315 5316 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 5317 GrowableArray<GCMemoryManager*> memory_managers(2); 5318 memory_managers.append(&_memory_manager); 5319 memory_managers.append(&_full_gc_memory_manager); 5320 return memory_managers; 5321 } 5322 5323 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 5324 GrowableArray<MemoryPool*> memory_pools(3); 5325 memory_pools.append(_eden_pool); 5326 memory_pools.append(_survivor_pool); 5327 memory_pools.append(_old_pool); 5328 return memory_pools; 5329 }