1 /* 2 * Copyright (c) 2001, 2016, 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/concurrentG1Refine.hpp" 33 #include "gc/g1/concurrentG1RefineThread.hpp" 34 #include "gc/g1/concurrentMarkThread.inline.hpp" 35 #include "gc/g1/g1Allocator.inline.hpp" 36 #include "gc/g1/g1CollectedHeap.inline.hpp" 37 #include "gc/g1/g1CollectionSet.hpp" 38 #include "gc/g1/g1CollectorPolicy.hpp" 39 #include "gc/g1/g1CollectorState.hpp" 40 #include "gc/g1/g1EvacStats.inline.hpp" 41 #include "gc/g1/g1GCPhaseTimes.hpp" 42 #include "gc/g1/g1HeapSizingPolicy.hpp" 43 #include "gc/g1/g1HeapTransition.hpp" 44 #include "gc/g1/g1HeapVerifier.hpp" 45 #include "gc/g1/g1HotCardCache.hpp" 46 #include "gc/g1/g1MarkSweep.hpp" 47 #include "gc/g1/g1OopClosures.inline.hpp" 48 #include "gc/g1/g1ParScanThreadState.inline.hpp" 49 #include "gc/g1/g1Policy.hpp" 50 #include "gc/g1/g1RegionToSpaceMapper.hpp" 51 #include "gc/g1/g1RemSet.inline.hpp" 52 #include "gc/g1/g1RootClosures.hpp" 53 #include "gc/g1/g1RootProcessor.hpp" 54 #include "gc/g1/g1StringDedup.hpp" 55 #include "gc/g1/g1YCTypes.hpp" 56 #include "gc/g1/heapRegion.inline.hpp" 57 #include "gc/g1/heapRegionRemSet.hpp" 58 #include "gc/g1/heapRegionSet.inline.hpp" 59 #include "gc/g1/suspendibleThreadSet.hpp" 60 #include "gc/g1/vm_operations_g1.hpp" 61 #include "gc/shared/gcHeapSummary.hpp" 62 #include "gc/shared/gcId.hpp" 63 #include "gc/shared/gcLocker.inline.hpp" 64 #include "gc/shared/gcTimer.hpp" 65 #include "gc/shared/gcTrace.hpp" 66 #include "gc/shared/gcTraceTime.inline.hpp" 67 #include "gc/shared/generationSpec.hpp" 68 #include "gc/shared/isGCActiveMark.hpp" 69 #include "gc/shared/preservedMarks.inline.hpp" 70 #include "gc/shared/referenceProcessor.inline.hpp" 71 #include "gc/shared/taskqueue.inline.hpp" 72 #include "logging/log.hpp" 73 #include "memory/allocation.hpp" 74 #include "memory/iterator.hpp" 75 #include "memory/resourceArea.hpp" 76 #include "oops/oop.inline.hpp" 77 #include "runtime/atomic.hpp" 78 #include "runtime/init.hpp" 79 #include "runtime/orderAccess.inline.hpp" 80 #include "runtime/vmThread.hpp" 81 #include "utilities/globalDefinitions.hpp" 82 #include "utilities/stack.inline.hpp" 83 84 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 85 86 // INVARIANTS/NOTES 87 // 88 // All allocation activity covered by the G1CollectedHeap interface is 89 // serialized by acquiring the HeapLock. This happens in mem_allocate 90 // and allocate_new_tlab, which are the "entry" points to the 91 // allocation code from the rest of the JVM. (Note that this does not 92 // apply to TLAB allocation, which is not part of this interface: it 93 // is done by clients of this interface.) 94 95 // Local to this file. 96 97 class RefineCardTableEntryClosure: public CardTableEntryClosure { 98 bool _concurrent; 99 public: 100 RefineCardTableEntryClosure() : _concurrent(true) { } 101 102 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 103 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, NULL); 104 // This path is executed by the concurrent refine or mutator threads, 105 // concurrently, and so we do not care if card_ptr contains references 106 // that point into the collection set. 107 assert(!oops_into_cset, "should be"); 108 109 if (_concurrent && SuspendibleThreadSet::should_yield()) { 110 // Caller will actually yield. 111 return false; 112 } 113 // Otherwise, we finished successfully; return true. 114 return true; 115 } 116 117 void set_concurrent(bool b) { _concurrent = b; } 118 }; 119 120 121 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 122 private: 123 size_t _num_dirtied; 124 G1CollectedHeap* _g1h; 125 G1SATBCardTableLoggingModRefBS* _g1_bs; 126 127 HeapRegion* region_for_card(jbyte* card_ptr) const { 128 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr)); 129 } 130 131 bool will_become_free(HeapRegion* hr) const { 132 // A region will be freed by free_collection_set if the region is in the 133 // collection set and has not had an evacuation failure. 134 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 135 } 136 137 public: 138 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(), 139 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { } 140 141 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 142 HeapRegion* hr = region_for_card(card_ptr); 143 144 // Should only dirty cards in regions that won't be freed. 145 if (!will_become_free(hr)) { 146 *card_ptr = CardTableModRefBS::dirty_card_val(); 147 _num_dirtied++; 148 } 149 150 return true; 151 } 152 153 size_t num_dirtied() const { return _num_dirtied; } 154 }; 155 156 157 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 158 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 159 } 160 161 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 162 // The from card cache is not the memory that is actually committed. So we cannot 163 // take advantage of the zero_filled parameter. 164 reset_from_card_cache(start_idx, num_regions); 165 } 166 167 // Returns true if the reference points to an object that 168 // can move in an incremental collection. 169 bool G1CollectedHeap::is_scavengable(const void* p) { 170 HeapRegion* hr = heap_region_containing(p); 171 return !hr->is_pinned(); 172 } 173 174 // Private methods. 175 176 HeapRegion* 177 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 178 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 179 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 180 if (!_secondary_free_list.is_empty()) { 181 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 182 "secondary_free_list has %u entries", 183 _secondary_free_list.length()); 184 // It looks as if there are free regions available on the 185 // secondary_free_list. Let's move them to the free_list and try 186 // again to allocate from it. 187 append_secondary_free_list(); 188 189 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 190 "empty we should have moved at least one entry to the free_list"); 191 HeapRegion* res = _hrm.allocate_free_region(is_old); 192 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 193 "allocated " HR_FORMAT " from secondary_free_list", 194 HR_FORMAT_PARAMS(res)); 195 return res; 196 } 197 198 // Wait here until we get notified either when (a) there are no 199 // more free regions coming or (b) some regions have been moved on 200 // the secondary_free_list. 201 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 202 } 203 204 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 205 "could not allocate from secondary_free_list"); 206 return NULL; 207 } 208 209 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 210 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 211 "the only time we use this to allocate a humongous region is " 212 "when we are allocating a single humongous region"); 213 214 HeapRegion* res; 215 if (G1StressConcRegionFreeing) { 216 if (!_secondary_free_list.is_empty()) { 217 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 218 "forced to look at the secondary_free_list"); 219 res = new_region_try_secondary_free_list(is_old); 220 if (res != NULL) { 221 return res; 222 } 223 } 224 } 225 226 res = _hrm.allocate_free_region(is_old); 227 228 if (res == NULL) { 229 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 230 "res == NULL, trying the secondary_free_list"); 231 res = new_region_try_secondary_free_list(is_old); 232 } 233 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 234 // Currently, only attempts to allocate GC alloc regions set 235 // do_expand to true. So, we should only reach here during a 236 // safepoint. If this assumption changes we might have to 237 // reconsider the use of _expand_heap_after_alloc_failure. 238 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 239 240 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 241 word_size * HeapWordSize); 242 243 if (expand(word_size * HeapWordSize)) { 244 // Given that expand() succeeded in expanding the heap, and we 245 // always expand the heap by an amount aligned to the heap 246 // region size, the free list should in theory not be empty. 247 // In either case allocate_free_region() will check for NULL. 248 res = _hrm.allocate_free_region(is_old); 249 } else { 250 _expand_heap_after_alloc_failure = false; 251 } 252 } 253 return res; 254 } 255 256 HeapWord* 257 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 258 uint num_regions, 259 size_t word_size, 260 AllocationContext_t context) { 261 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 262 assert(is_humongous(word_size), "word_size should be humongous"); 263 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 264 265 // Index of last region in the series. 266 uint last = first + num_regions - 1; 267 268 // We need to initialize the region(s) we just discovered. This is 269 // a bit tricky given that it can happen concurrently with 270 // refinement threads refining cards on these regions and 271 // potentially wanting to refine the BOT as they are scanning 272 // those cards (this can happen shortly after a cleanup; see CR 273 // 6991377). So we have to set up the region(s) carefully and in 274 // a specific order. 275 276 // The word size sum of all the regions we will allocate. 277 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 278 assert(word_size <= word_size_sum, "sanity"); 279 280 // This will be the "starts humongous" region. 281 HeapRegion* first_hr = region_at(first); 282 // The header of the new object will be placed at the bottom of 283 // the first region. 284 HeapWord* new_obj = first_hr->bottom(); 285 // This will be the new top of the new object. 286 HeapWord* obj_top = new_obj + word_size; 287 288 // First, we need to zero the header of the space that we will be 289 // allocating. When we update top further down, some refinement 290 // threads might try to scan the region. By zeroing the header we 291 // ensure that any thread that will try to scan the region will 292 // come across the zero klass word and bail out. 293 // 294 // NOTE: It would not have been correct to have used 295 // CollectedHeap::fill_with_object() and make the space look like 296 // an int array. The thread that is doing the allocation will 297 // later update the object header to a potentially different array 298 // type and, for a very short period of time, the klass and length 299 // fields will be inconsistent. This could cause a refinement 300 // thread to calculate the object size incorrectly. 301 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 302 303 // Next, pad out the unused tail of the last region with filler 304 // objects, for improved usage accounting. 305 // How many words we use for filler objects. 306 size_t word_fill_size = word_size_sum - word_size; 307 308 // How many words memory we "waste" which cannot hold a filler object. 309 size_t words_not_fillable = 0; 310 311 if (word_fill_size >= min_fill_size()) { 312 fill_with_objects(obj_top, word_fill_size); 313 } else if (word_fill_size > 0) { 314 // We have space to fill, but we cannot fit an object there. 315 words_not_fillable = word_fill_size; 316 word_fill_size = 0; 317 } 318 319 // We will set up the first region as "starts humongous". This 320 // will also update the BOT covering all the regions to reflect 321 // that there is a single object that starts at the bottom of the 322 // first region. 323 first_hr->set_starts_humongous(obj_top, word_fill_size); 324 first_hr->set_allocation_context(context); 325 // Then, if there are any, we will set up the "continues 326 // humongous" regions. 327 HeapRegion* hr = NULL; 328 for (uint i = first + 1; i <= last; ++i) { 329 hr = region_at(i); 330 hr->set_continues_humongous(first_hr); 331 hr->set_allocation_context(context); 332 } 333 334 // Up to this point no concurrent thread would have been able to 335 // do any scanning on any region in this series. All the top 336 // fields still point to bottom, so the intersection between 337 // [bottom,top] and [card_start,card_end] will be empty. Before we 338 // update the top fields, we'll do a storestore to make sure that 339 // no thread sees the update to top before the zeroing of the 340 // object header and the BOT initialization. 341 OrderAccess::storestore(); 342 343 // Now, we will update the top fields of the "continues humongous" 344 // regions except the last one. 345 for (uint i = first; i < last; ++i) { 346 hr = region_at(i); 347 hr->set_top(hr->end()); 348 } 349 350 hr = region_at(last); 351 // If we cannot fit a filler object, we must set top to the end 352 // of the humongous object, otherwise we cannot iterate the heap 353 // and the BOT will not be complete. 354 hr->set_top(hr->end() - words_not_fillable); 355 356 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 357 "obj_top should be in last region"); 358 359 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 360 361 assert(words_not_fillable == 0 || 362 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 363 "Miscalculation in humongous allocation"); 364 365 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 366 367 for (uint i = first; i <= last; ++i) { 368 hr = region_at(i); 369 _humongous_set.add(hr); 370 _hr_printer.alloc(hr); 371 } 372 373 return new_obj; 374 } 375 376 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 377 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 378 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 379 } 380 381 // If could fit into free regions w/o expansion, try. 382 // Otherwise, if can expand, do so. 383 // Otherwise, if using ex regions might help, try with ex given back. 384 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 385 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 386 387 _verifier->verify_region_sets_optional(); 388 389 uint first = G1_NO_HRM_INDEX; 390 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 391 392 if (obj_regions == 1) { 393 // Only one region to allocate, try to use a fast path by directly allocating 394 // from the free lists. Do not try to expand here, we will potentially do that 395 // later. 396 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 397 if (hr != NULL) { 398 first = hr->hrm_index(); 399 } 400 } else { 401 // We can't allocate humongous regions spanning more than one region while 402 // cleanupComplete() is running, since some of the regions we find to be 403 // empty might not yet be added to the free list. It is not straightforward 404 // to know in which list they are on so that we can remove them. We only 405 // need to do this if we need to allocate more than one region to satisfy the 406 // current humongous allocation request. If we are only allocating one region 407 // we use the one-region region allocation code (see above), that already 408 // potentially waits for regions from the secondary free list. 409 wait_while_free_regions_coming(); 410 append_secondary_free_list_if_not_empty_with_lock(); 411 412 // Policy: Try only empty regions (i.e. already committed first). Maybe we 413 // are lucky enough to find some. 414 first = _hrm.find_contiguous_only_empty(obj_regions); 415 if (first != G1_NO_HRM_INDEX) { 416 _hrm.allocate_free_regions_starting_at(first, obj_regions); 417 } 418 } 419 420 if (first == G1_NO_HRM_INDEX) { 421 // Policy: We could not find enough regions for the humongous object in the 422 // free list. Look through the heap to find a mix of free and uncommitted regions. 423 // If so, try expansion. 424 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 425 if (first != G1_NO_HRM_INDEX) { 426 // We found something. Make sure these regions are committed, i.e. expand 427 // the heap. Alternatively we could do a defragmentation GC. 428 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", 429 word_size * HeapWordSize); 430 431 _hrm.expand_at(first, obj_regions, workers()); 432 g1_policy()->record_new_heap_size(num_regions()); 433 434 #ifdef ASSERT 435 for (uint i = first; i < first + obj_regions; ++i) { 436 HeapRegion* hr = region_at(i); 437 assert(hr->is_free(), "sanity"); 438 assert(hr->is_empty(), "sanity"); 439 assert(is_on_master_free_list(hr), "sanity"); 440 } 441 #endif 442 _hrm.allocate_free_regions_starting_at(first, obj_regions); 443 } else { 444 // Policy: Potentially trigger a defragmentation GC. 445 } 446 } 447 448 HeapWord* result = NULL; 449 if (first != G1_NO_HRM_INDEX) { 450 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 451 word_size, context); 452 assert(result != NULL, "it should always return a valid result"); 453 454 // A successful humongous object allocation changes the used space 455 // information of the old generation so we need to recalculate the 456 // sizes and update the jstat counters here. 457 g1mm()->update_sizes(); 458 } 459 460 _verifier->verify_region_sets_optional(); 461 462 return result; 463 } 464 465 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 466 assert_heap_not_locked_and_not_at_safepoint(); 467 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 468 469 uint dummy_gc_count_before; 470 uint dummy_gclocker_retry_count = 0; 471 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 472 } 473 474 HeapWord* 475 G1CollectedHeap::mem_allocate(size_t word_size, 476 bool* gc_overhead_limit_was_exceeded) { 477 assert_heap_not_locked_and_not_at_safepoint(); 478 479 // Loop until the allocation is satisfied, or unsatisfied after GC. 480 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 481 uint gc_count_before; 482 483 HeapWord* result = NULL; 484 if (!is_humongous(word_size)) { 485 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 486 } else { 487 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 488 } 489 if (result != NULL) { 490 return result; 491 } 492 493 // Create the garbage collection operation... 494 VM_G1CollectForAllocation op(gc_count_before, word_size); 495 op.set_allocation_context(AllocationContext::current()); 496 497 // ...and get the VM thread to execute it. 498 VMThread::execute(&op); 499 500 if (op.prologue_succeeded() && op.pause_succeeded()) { 501 // If the operation was successful we'll return the result even 502 // if it is NULL. If the allocation attempt failed immediately 503 // after a Full GC, it's unlikely we'll be able to allocate now. 504 HeapWord* result = op.result(); 505 if (result != NULL && !is_humongous(word_size)) { 506 // Allocations that take place on VM operations do not do any 507 // card dirtying and we have to do it here. We only have to do 508 // this for non-humongous allocations, though. 509 dirty_young_block(result, word_size); 510 } 511 return result; 512 } else { 513 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 514 return NULL; 515 } 516 assert(op.result() == NULL, 517 "the result should be NULL if the VM op did not succeed"); 518 } 519 520 // Give a warning if we seem to be looping forever. 521 if ((QueuedAllocationWarningCount > 0) && 522 (try_count % QueuedAllocationWarningCount == 0)) { 523 log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count); 524 } 525 } 526 527 ShouldNotReachHere(); 528 return NULL; 529 } 530 531 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 532 AllocationContext_t context, 533 uint* gc_count_before_ret, 534 uint* gclocker_retry_count_ret) { 535 // Make sure you read the note in attempt_allocation_humongous(). 536 537 assert_heap_not_locked_and_not_at_safepoint(); 538 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 539 "be called for humongous allocation requests"); 540 541 // We should only get here after the first-level allocation attempt 542 // (attempt_allocation()) failed to allocate. 543 544 // We will loop until a) we manage to successfully perform the 545 // allocation or b) we successfully schedule a collection which 546 // fails to perform the allocation. b) is the only case when we'll 547 // return NULL. 548 HeapWord* result = NULL; 549 for (int try_count = 1; /* we'll return */; try_count += 1) { 550 bool should_try_gc; 551 uint gc_count_before; 552 553 { 554 MutexLockerEx x(Heap_lock); 555 result = _allocator->attempt_allocation_locked(word_size, context); 556 if (result != NULL) { 557 return result; 558 } 559 560 if (GCLocker::is_active_and_needs_gc()) { 561 if (g1_policy()->can_expand_young_list()) { 562 // No need for an ergo verbose message here, 563 // can_expand_young_list() does this when it returns true. 564 result = _allocator->attempt_allocation_force(word_size, context); 565 if (result != NULL) { 566 return result; 567 } 568 } 569 should_try_gc = false; 570 } else { 571 // The GCLocker may not be active but the GCLocker initiated 572 // GC may not yet have been performed (GCLocker::needs_gc() 573 // returns true). In this case we do not try this GC and 574 // wait until the GCLocker initiated GC is performed, and 575 // then retry the allocation. 576 if (GCLocker::needs_gc()) { 577 should_try_gc = false; 578 } else { 579 // Read the GC count while still holding the Heap_lock. 580 gc_count_before = total_collections(); 581 should_try_gc = true; 582 } 583 } 584 } 585 586 if (should_try_gc) { 587 bool succeeded; 588 result = do_collection_pause(word_size, gc_count_before, &succeeded, 589 GCCause::_g1_inc_collection_pause); 590 if (result != NULL) { 591 assert(succeeded, "only way to get back a non-NULL result"); 592 return result; 593 } 594 595 if (succeeded) { 596 // If we get here we successfully scheduled a collection which 597 // failed to allocate. No point in trying to allocate 598 // further. We'll just return NULL. 599 MutexLockerEx x(Heap_lock); 600 *gc_count_before_ret = total_collections(); 601 return NULL; 602 } 603 } else { 604 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 605 MutexLockerEx x(Heap_lock); 606 *gc_count_before_ret = total_collections(); 607 return NULL; 608 } 609 // The GCLocker is either active or the GCLocker initiated 610 // GC has not yet been performed. Stall until it is and 611 // then retry the allocation. 612 GCLocker::stall_until_clear(); 613 (*gclocker_retry_count_ret) += 1; 614 } 615 616 // We can reach here if we were unsuccessful in scheduling a 617 // collection (because another thread beat us to it) or if we were 618 // stalled due to the GC locker. In either can we should retry the 619 // allocation attempt in case another thread successfully 620 // performed a collection and reclaimed enough space. We do the 621 // first attempt (without holding the Heap_lock) here and the 622 // follow-on attempt will be at the start of the next loop 623 // iteration (after taking the Heap_lock). 624 result = _allocator->attempt_allocation(word_size, context); 625 if (result != NULL) { 626 return result; 627 } 628 629 // Give a warning if we seem to be looping forever. 630 if ((QueuedAllocationWarningCount > 0) && 631 (try_count % QueuedAllocationWarningCount == 0)) { 632 log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() " 633 "retries %d times", try_count); 634 } 635 } 636 637 ShouldNotReachHere(); 638 return NULL; 639 } 640 641 void G1CollectedHeap::begin_archive_alloc_range() { 642 assert_at_safepoint(true /* should_be_vm_thread */); 643 if (_archive_allocator == NULL) { 644 _archive_allocator = G1ArchiveAllocator::create_allocator(this); 645 } 646 } 647 648 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 649 // Allocations in archive regions cannot be of a size that would be considered 650 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 651 // may be different at archive-restore time. 652 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 653 } 654 655 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 656 assert_at_safepoint(true /* should_be_vm_thread */); 657 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 658 if (is_archive_alloc_too_large(word_size)) { 659 return NULL; 660 } 661 return _archive_allocator->archive_mem_allocate(word_size); 662 } 663 664 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 665 size_t end_alignment_in_bytes) { 666 assert_at_safepoint(true /* should_be_vm_thread */); 667 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 668 669 // Call complete_archive to do the real work, filling in the MemRegion 670 // array with the archive regions. 671 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 672 delete _archive_allocator; 673 _archive_allocator = NULL; 674 } 675 676 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 677 assert(ranges != NULL, "MemRegion array NULL"); 678 assert(count != 0, "No MemRegions provided"); 679 MemRegion reserved = _hrm.reserved(); 680 for (size_t i = 0; i < count; i++) { 681 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 682 return false; 683 } 684 } 685 return true; 686 } 687 688 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) { 689 assert(!is_init_completed(), "Expect to be called at JVM init time"); 690 assert(ranges != NULL, "MemRegion array NULL"); 691 assert(count != 0, "No MemRegions provided"); 692 MutexLockerEx x(Heap_lock); 693 694 MemRegion reserved = _hrm.reserved(); 695 HeapWord* prev_last_addr = NULL; 696 HeapRegion* prev_last_region = NULL; 697 698 // Temporarily disable pretouching of heap pages. This interface is used 699 // when mmap'ing archived heap data in, so pre-touching is wasted. 700 FlagSetting fs(AlwaysPreTouch, false); 701 702 // Enable archive object checking in G1MarkSweep. We have to let it know 703 // about each archive range, so that objects in those ranges aren't marked. 704 G1MarkSweep::enable_archive_object_check(); 705 706 // For each specified MemRegion range, allocate the corresponding G1 707 // regions and mark them as archive regions. We expect the ranges in 708 // ascending starting address order, without overlap. 709 for (size_t i = 0; i < count; i++) { 710 MemRegion curr_range = ranges[i]; 711 HeapWord* start_address = curr_range.start(); 712 size_t word_size = curr_range.word_size(); 713 HeapWord* last_address = curr_range.last(); 714 size_t commits = 0; 715 716 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 717 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 718 p2i(start_address), p2i(last_address)); 719 guarantee(start_address > prev_last_addr, 720 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 721 p2i(start_address), p2i(prev_last_addr)); 722 prev_last_addr = last_address; 723 724 // Check for ranges that start in the same G1 region in which the previous 725 // range ended, and adjust the start address so we don't try to allocate 726 // the same region again. If the current range is entirely within that 727 // region, skip it, just adjusting the recorded top. 728 HeapRegion* start_region = _hrm.addr_to_region(start_address); 729 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 730 start_address = start_region->end(); 731 if (start_address > last_address) { 732 increase_used(word_size * HeapWordSize); 733 start_region->set_top(last_address + 1); 734 continue; 735 } 736 start_region->set_top(start_address); 737 curr_range = MemRegion(start_address, last_address + 1); 738 start_region = _hrm.addr_to_region(start_address); 739 } 740 741 // Perform the actual region allocation, exiting if it fails. 742 // Then note how much new space we have allocated. 743 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) { 744 return false; 745 } 746 increase_used(word_size * HeapWordSize); 747 if (commits != 0) { 748 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 749 HeapRegion::GrainWords * HeapWordSize * commits); 750 751 } 752 753 // Mark each G1 region touched by the range as archive, add it to the old set, 754 // and set the allocation context and top. 755 HeapRegion* curr_region = _hrm.addr_to_region(start_address); 756 HeapRegion* last_region = _hrm.addr_to_region(last_address); 757 prev_last_region = last_region; 758 759 while (curr_region != NULL) { 760 assert(curr_region->is_empty() && !curr_region->is_pinned(), 761 "Region already in use (index %u)", curr_region->hrm_index()); 762 curr_region->set_allocation_context(AllocationContext::system()); 763 curr_region->set_archive(); 764 _hr_printer.alloc(curr_region); 765 _old_set.add(curr_region); 766 if (curr_region != last_region) { 767 curr_region->set_top(curr_region->end()); 768 curr_region = _hrm.next_region_in_heap(curr_region); 769 } else { 770 curr_region->set_top(last_address + 1); 771 curr_region = NULL; 772 } 773 } 774 775 // Notify mark-sweep of the archive range. 776 G1MarkSweep::set_range_archive(curr_range, true); 777 } 778 return true; 779 } 780 781 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 782 assert(!is_init_completed(), "Expect to be called at JVM init time"); 783 assert(ranges != NULL, "MemRegion array NULL"); 784 assert(count != 0, "No MemRegions provided"); 785 MemRegion reserved = _hrm.reserved(); 786 HeapWord *prev_last_addr = NULL; 787 HeapRegion* prev_last_region = NULL; 788 789 // For each MemRegion, create filler objects, if needed, in the G1 regions 790 // that contain the address range. The address range actually within the 791 // MemRegion will not be modified. That is assumed to have been initialized 792 // elsewhere, probably via an mmap of archived heap data. 793 MutexLockerEx x(Heap_lock); 794 for (size_t i = 0; i < count; i++) { 795 HeapWord* start_address = ranges[i].start(); 796 HeapWord* last_address = ranges[i].last(); 797 798 assert(reserved.contains(start_address) && reserved.contains(last_address), 799 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 800 p2i(start_address), p2i(last_address)); 801 assert(start_address > prev_last_addr, 802 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 803 p2i(start_address), p2i(prev_last_addr)); 804 805 HeapRegion* start_region = _hrm.addr_to_region(start_address); 806 HeapRegion* last_region = _hrm.addr_to_region(last_address); 807 HeapWord* bottom_address = start_region->bottom(); 808 809 // Check for a range beginning in the same region in which the 810 // previous one ended. 811 if (start_region == prev_last_region) { 812 bottom_address = prev_last_addr + 1; 813 } 814 815 // Verify that the regions were all marked as archive regions by 816 // alloc_archive_regions. 817 HeapRegion* curr_region = start_region; 818 while (curr_region != NULL) { 819 guarantee(curr_region->is_archive(), 820 "Expected archive region at index %u", curr_region->hrm_index()); 821 if (curr_region != last_region) { 822 curr_region = _hrm.next_region_in_heap(curr_region); 823 } else { 824 curr_region = NULL; 825 } 826 } 827 828 prev_last_addr = last_address; 829 prev_last_region = last_region; 830 831 // Fill the memory below the allocated range with dummy object(s), 832 // if the region bottom does not match the range start, or if the previous 833 // range ended within the same G1 region, and there is a gap. 834 if (start_address != bottom_address) { 835 size_t fill_size = pointer_delta(start_address, bottom_address); 836 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 837 increase_used(fill_size * HeapWordSize); 838 } 839 } 840 } 841 842 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size, 843 uint* gc_count_before_ret, 844 uint* gclocker_retry_count_ret) { 845 assert_heap_not_locked_and_not_at_safepoint(); 846 assert(!is_humongous(word_size), "attempt_allocation() should not " 847 "be called for humongous allocation requests"); 848 849 AllocationContext_t context = AllocationContext::current(); 850 HeapWord* result = _allocator->attempt_allocation(word_size, context); 851 852 if (result == NULL) { 853 result = attempt_allocation_slow(word_size, 854 context, 855 gc_count_before_ret, 856 gclocker_retry_count_ret); 857 } 858 assert_heap_not_locked(); 859 if (result != NULL) { 860 dirty_young_block(result, word_size); 861 } 862 return result; 863 } 864 865 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 866 assert(!is_init_completed(), "Expect to be called at JVM init time"); 867 assert(ranges != NULL, "MemRegion array NULL"); 868 assert(count != 0, "No MemRegions provided"); 869 MemRegion reserved = _hrm.reserved(); 870 HeapWord* prev_last_addr = NULL; 871 HeapRegion* prev_last_region = NULL; 872 size_t size_used = 0; 873 size_t uncommitted_regions = 0; 874 875 // For each Memregion, free the G1 regions that constitute it, and 876 // notify mark-sweep that the range is no longer to be considered 'archive.' 877 MutexLockerEx x(Heap_lock); 878 for (size_t i = 0; i < count; i++) { 879 HeapWord* start_address = ranges[i].start(); 880 HeapWord* last_address = ranges[i].last(); 881 882 assert(reserved.contains(start_address) && reserved.contains(last_address), 883 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 884 p2i(start_address), p2i(last_address)); 885 assert(start_address > prev_last_addr, 886 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 887 p2i(start_address), p2i(prev_last_addr)); 888 size_used += ranges[i].byte_size(); 889 prev_last_addr = last_address; 890 891 HeapRegion* start_region = _hrm.addr_to_region(start_address); 892 HeapRegion* last_region = _hrm.addr_to_region(last_address); 893 894 // Check for ranges that start in the same G1 region in which the previous 895 // range ended, and adjust the start address so we don't try to free 896 // the same region again. If the current range is entirely within that 897 // region, skip it. 898 if (start_region == prev_last_region) { 899 start_address = start_region->end(); 900 if (start_address > last_address) { 901 continue; 902 } 903 start_region = _hrm.addr_to_region(start_address); 904 } 905 prev_last_region = last_region; 906 907 // After verifying that each region was marked as an archive region by 908 // alloc_archive_regions, set it free and empty and uncommit it. 909 HeapRegion* curr_region = start_region; 910 while (curr_region != NULL) { 911 guarantee(curr_region->is_archive(), 912 "Expected archive region at index %u", curr_region->hrm_index()); 913 uint curr_index = curr_region->hrm_index(); 914 _old_set.remove(curr_region); 915 curr_region->set_free(); 916 curr_region->set_top(curr_region->bottom()); 917 if (curr_region != last_region) { 918 curr_region = _hrm.next_region_in_heap(curr_region); 919 } else { 920 curr_region = NULL; 921 } 922 _hrm.shrink_at(curr_index, 1); 923 uncommitted_regions++; 924 } 925 926 // Notify mark-sweep that this is no longer an archive range. 927 G1MarkSweep::set_range_archive(ranges[i], false); 928 } 929 930 if (uncommitted_regions != 0) { 931 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 932 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 933 } 934 decrease_used(size_used); 935 } 936 937 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 938 uint* gc_count_before_ret, 939 uint* gclocker_retry_count_ret) { 940 // The structure of this method has a lot of similarities to 941 // attempt_allocation_slow(). The reason these two were not merged 942 // into a single one is that such a method would require several "if 943 // allocation is not humongous do this, otherwise do that" 944 // conditional paths which would obscure its flow. In fact, an early 945 // version of this code did use a unified method which was harder to 946 // follow and, as a result, it had subtle bugs that were hard to 947 // track down. So keeping these two methods separate allows each to 948 // be more readable. It will be good to keep these two in sync as 949 // much as possible. 950 951 assert_heap_not_locked_and_not_at_safepoint(); 952 assert(is_humongous(word_size), "attempt_allocation_humongous() " 953 "should only be called for humongous allocations"); 954 955 // Humongous objects can exhaust the heap quickly, so we should check if we 956 // need to start a marking cycle at each humongous object allocation. We do 957 // the check before we do the actual allocation. The reason for doing it 958 // before the allocation is that we avoid having to keep track of the newly 959 // allocated memory while we do a GC. 960 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 961 word_size)) { 962 collect(GCCause::_g1_humongous_allocation); 963 } 964 965 // We will loop until a) we manage to successfully perform the 966 // allocation or b) we successfully schedule a collection which 967 // fails to perform the allocation. b) is the only case when we'll 968 // return NULL. 969 HeapWord* result = NULL; 970 for (int try_count = 1; /* we'll return */; try_count += 1) { 971 bool should_try_gc; 972 uint gc_count_before; 973 974 { 975 MutexLockerEx x(Heap_lock); 976 977 // Given that humongous objects are not allocated in young 978 // regions, we'll first try to do the allocation without doing a 979 // collection hoping that there's enough space in the heap. 980 result = humongous_obj_allocate(word_size, AllocationContext::current()); 981 if (result != NULL) { 982 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 983 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 984 return result; 985 } 986 987 if (GCLocker::is_active_and_needs_gc()) { 988 should_try_gc = false; 989 } else { 990 // The GCLocker may not be active but the GCLocker initiated 991 // GC may not yet have been performed (GCLocker::needs_gc() 992 // returns true). In this case we do not try this GC and 993 // wait until the GCLocker initiated GC is performed, and 994 // then retry the allocation. 995 if (GCLocker::needs_gc()) { 996 should_try_gc = false; 997 } else { 998 // Read the GC count while still holding the Heap_lock. 999 gc_count_before = total_collections(); 1000 should_try_gc = true; 1001 } 1002 } 1003 } 1004 1005 if (should_try_gc) { 1006 // If we failed to allocate the humongous object, we should try to 1007 // do a collection pause (if we're allowed) in case it reclaims 1008 // enough space for the allocation to succeed after the pause. 1009 1010 bool succeeded; 1011 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1012 GCCause::_g1_humongous_allocation); 1013 if (result != NULL) { 1014 assert(succeeded, "only way to get back a non-NULL result"); 1015 return result; 1016 } 1017 1018 if (succeeded) { 1019 // If we get here we successfully scheduled a collection which 1020 // failed to allocate. No point in trying to allocate 1021 // further. We'll just return NULL. 1022 MutexLockerEx x(Heap_lock); 1023 *gc_count_before_ret = total_collections(); 1024 return NULL; 1025 } 1026 } else { 1027 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1028 MutexLockerEx x(Heap_lock); 1029 *gc_count_before_ret = total_collections(); 1030 return NULL; 1031 } 1032 // The GCLocker is either active or the GCLocker initiated 1033 // GC has not yet been performed. Stall until it is and 1034 // then retry the allocation. 1035 GCLocker::stall_until_clear(); 1036 (*gclocker_retry_count_ret) += 1; 1037 } 1038 1039 // We can reach here if we were unsuccessful in scheduling a 1040 // collection (because another thread beat us to it) or if we were 1041 // stalled due to the GC locker. In either can we should retry the 1042 // allocation attempt in case another thread successfully 1043 // performed a collection and reclaimed enough space. Give a 1044 // warning if we seem to be looping forever. 1045 1046 if ((QueuedAllocationWarningCount > 0) && 1047 (try_count % QueuedAllocationWarningCount == 0)) { 1048 log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() " 1049 "retries %d times", try_count); 1050 } 1051 } 1052 1053 ShouldNotReachHere(); 1054 return NULL; 1055 } 1056 1057 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1058 AllocationContext_t context, 1059 bool expect_null_mutator_alloc_region) { 1060 assert_at_safepoint(true /* should_be_vm_thread */); 1061 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region, 1062 "the current alloc region was unexpectedly found to be non-NULL"); 1063 1064 if (!is_humongous(word_size)) { 1065 return _allocator->attempt_allocation_locked(word_size, context); 1066 } else { 1067 HeapWord* result = humongous_obj_allocate(word_size, context); 1068 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1069 collector_state()->set_initiate_conc_mark_if_possible(true); 1070 } 1071 return result; 1072 } 1073 1074 ShouldNotReachHere(); 1075 } 1076 1077 class PostMCRemSetClearClosure: public HeapRegionClosure { 1078 G1CollectedHeap* _g1h; 1079 ModRefBarrierSet* _mr_bs; 1080 public: 1081 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1082 _g1h(g1h), _mr_bs(mr_bs) {} 1083 1084 bool doHeapRegion(HeapRegion* r) { 1085 HeapRegionRemSet* hrrs = r->rem_set(); 1086 1087 _g1h->reset_gc_time_stamps(r); 1088 1089 if (r->is_continues_humongous()) { 1090 // We'll assert that the strong code root list and RSet is empty 1091 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1092 assert(hrrs->occupied() == 0, "RSet should be empty"); 1093 } else { 1094 hrrs->clear(); 1095 } 1096 // You might think here that we could clear just the cards 1097 // corresponding to the used region. But no: if we leave a dirty card 1098 // in a region we might allocate into, then it would prevent that card 1099 // from being enqueued, and cause it to be missed. 1100 // Re: the performance cost: we shouldn't be doing full GC anyway! 1101 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1102 1103 return false; 1104 } 1105 }; 1106 1107 void G1CollectedHeap::clear_rsets_post_compaction() { 1108 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1109 heap_region_iterate(&rs_clear); 1110 } 1111 1112 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1113 G1CollectedHeap* _g1h; 1114 UpdateRSOopClosure _cl; 1115 public: 1116 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) : 1117 _cl(g1->g1_rem_set(), worker_i), 1118 _g1h(g1) 1119 { } 1120 1121 bool doHeapRegion(HeapRegion* r) { 1122 if (!r->is_continues_humongous()) { 1123 _cl.set_from(r); 1124 r->oop_iterate(&_cl); 1125 } 1126 return false; 1127 } 1128 }; 1129 1130 class ParRebuildRSTask: public AbstractGangTask { 1131 G1CollectedHeap* _g1; 1132 HeapRegionClaimer _hrclaimer; 1133 1134 public: 1135 ParRebuildRSTask(G1CollectedHeap* g1) : 1136 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {} 1137 1138 void work(uint worker_id) { 1139 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1140 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer); 1141 } 1142 }; 1143 1144 class PostCompactionPrinterClosure: public HeapRegionClosure { 1145 private: 1146 G1HRPrinter* _hr_printer; 1147 public: 1148 bool doHeapRegion(HeapRegion* hr) { 1149 assert(!hr->is_young(), "not expecting to find young regions"); 1150 _hr_printer->post_compaction(hr); 1151 return false; 1152 } 1153 1154 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1155 : _hr_printer(hr_printer) { } 1156 }; 1157 1158 void G1CollectedHeap::print_hrm_post_compaction() { 1159 if (_hr_printer.is_active()) { 1160 PostCompactionPrinterClosure cl(hr_printer()); 1161 heap_region_iterate(&cl); 1162 } 1163 1164 } 1165 1166 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1167 bool clear_all_soft_refs) { 1168 assert_at_safepoint(true /* should_be_vm_thread */); 1169 1170 if (GCLocker::check_active_before_gc()) { 1171 return false; 1172 } 1173 1174 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1175 gc_timer->register_gc_start(); 1176 1177 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1178 GCIdMark gc_id_mark; 1179 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1180 1181 SvcGCMarker sgcm(SvcGCMarker::FULL); 1182 ResourceMark rm; 1183 1184 print_heap_before_gc(); 1185 print_heap_regions(); 1186 trace_heap_before_gc(gc_tracer); 1187 1188 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1189 1190 _verifier->verify_region_sets_optional(); 1191 1192 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1193 collector_policy()->should_clear_all_soft_refs(); 1194 1195 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1196 1197 { 1198 IsGCActiveMark x; 1199 1200 // Timing 1201 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1202 GCTraceCPUTime tcpu; 1203 1204 { 1205 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1206 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1207 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1208 1209 G1HeapTransition heap_transition(this); 1210 g1_policy()->record_full_collection_start(); 1211 1212 // Note: When we have a more flexible GC logging framework that 1213 // allows us to add optional attributes to a GC log record we 1214 // could consider timing and reporting how long we wait in the 1215 // following two methods. 1216 wait_while_free_regions_coming(); 1217 // If we start the compaction before the CM threads finish 1218 // scanning the root regions we might trip them over as we'll 1219 // be moving objects / updating references. So let's wait until 1220 // they are done. By telling them to abort, they should complete 1221 // early. 1222 _cm->root_regions()->abort(); 1223 _cm->root_regions()->wait_until_scan_finished(); 1224 append_secondary_free_list_if_not_empty_with_lock(); 1225 1226 gc_prologue(true); 1227 increment_total_collections(true /* full gc */); 1228 increment_old_marking_cycles_started(); 1229 1230 assert(used() == recalculate_used(), "Should be equal"); 1231 1232 _verifier->verify_before_gc(); 1233 1234 _verifier->check_bitmaps("Full GC Start"); 1235 pre_full_gc_dump(gc_timer); 1236 1237 #if defined(COMPILER2) || INCLUDE_JVMCI 1238 DerivedPointerTable::clear(); 1239 #endif 1240 1241 // Disable discovery and empty the discovered lists 1242 // for the CM ref processor. 1243 ref_processor_cm()->disable_discovery(); 1244 ref_processor_cm()->abandon_partial_discovery(); 1245 ref_processor_cm()->verify_no_references_recorded(); 1246 1247 // Abandon current iterations of concurrent marking and concurrent 1248 // refinement, if any are in progress. 1249 concurrent_mark()->abort(); 1250 1251 // Make sure we'll choose a new allocation region afterwards. 1252 _allocator->release_mutator_alloc_region(); 1253 _allocator->abandon_gc_alloc_regions(); 1254 g1_rem_set()->cleanupHRRS(); 1255 1256 // We may have added regions to the current incremental collection 1257 // set between the last GC or pause and now. We need to clear the 1258 // incremental collection set and then start rebuilding it afresh 1259 // after this full GC. 1260 abandon_collection_set(collection_set()); 1261 1262 tear_down_region_sets(false /* free_list_only */); 1263 collector_state()->set_gcs_are_young(true); 1264 1265 // See the comments in g1CollectedHeap.hpp and 1266 // G1CollectedHeap::ref_processing_init() about 1267 // how reference processing currently works in G1. 1268 1269 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1270 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1271 1272 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1273 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1274 1275 ref_processor_stw()->enable_discovery(); 1276 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1277 1278 // Do collection work 1279 { 1280 HandleMark hm; // Discard invalid handles created during gc 1281 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1282 } 1283 1284 assert(num_free_regions() == 0, "we should not have added any free regions"); 1285 rebuild_region_sets(false /* free_list_only */); 1286 1287 // Enqueue any discovered reference objects that have 1288 // not been removed from the discovered lists. 1289 ref_processor_stw()->enqueue_discovered_references(); 1290 1291 #if defined(COMPILER2) || INCLUDE_JVMCI 1292 DerivedPointerTable::update_pointers(); 1293 #endif 1294 1295 MemoryService::track_memory_usage(); 1296 1297 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1298 ref_processor_stw()->verify_no_references_recorded(); 1299 1300 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1301 ClassLoaderDataGraph::purge(); 1302 MetaspaceAux::verify_metrics(); 1303 1304 // Note: since we've just done a full GC, concurrent 1305 // marking is no longer active. Therefore we need not 1306 // re-enable reference discovery for the CM ref processor. 1307 // That will be done at the start of the next marking cycle. 1308 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1309 ref_processor_cm()->verify_no_references_recorded(); 1310 1311 reset_gc_time_stamp(); 1312 // Since everything potentially moved, we will clear all remembered 1313 // sets, and clear all cards. Later we will rebuild remembered 1314 // sets. We will also reset the GC time stamps of the regions. 1315 clear_rsets_post_compaction(); 1316 check_gc_time_stamps(); 1317 1318 resize_if_necessary_after_full_collection(); 1319 1320 // We should do this after we potentially resize the heap so 1321 // that all the COMMIT / UNCOMMIT events are generated before 1322 // the compaction events. 1323 print_hrm_post_compaction(); 1324 1325 if (_hot_card_cache->use_cache()) { 1326 _hot_card_cache->reset_card_counts(); 1327 _hot_card_cache->reset_hot_cache(); 1328 } 1329 1330 // Rebuild remembered sets of all regions. 1331 uint n_workers = 1332 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1333 workers()->active_workers(), 1334 Threads::number_of_non_daemon_threads()); 1335 workers()->update_active_workers(n_workers); 1336 log_info(gc,task)("Using %u workers of %u to rebuild remembered set", n_workers, workers()->total_workers()); 1337 1338 ParRebuildRSTask rebuild_rs_task(this); 1339 workers()->run_task(&rebuild_rs_task); 1340 1341 // Rebuild the strong code root lists for each region 1342 rebuild_strong_code_roots(); 1343 1344 if (true) { // FIXME 1345 MetaspaceGC::compute_new_size(); 1346 } 1347 1348 #ifdef TRACESPINNING 1349 ParallelTaskTerminator::print_termination_counts(); 1350 #endif 1351 1352 // Discard all rset updates 1353 JavaThread::dirty_card_queue_set().abandon_logs(); 1354 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1355 1356 // At this point there should be no regions in the 1357 // entire heap tagged as young. 1358 assert(check_young_list_empty(), "young list should be empty at this point"); 1359 1360 // Update the number of full collections that have been completed. 1361 increment_old_marking_cycles_completed(false /* concurrent */); 1362 1363 _hrm.verify_optional(); 1364 _verifier->verify_region_sets_optional(); 1365 1366 _verifier->verify_after_gc(); 1367 1368 // Clear the previous marking bitmap, if needed for bitmap verification. 1369 // Note we cannot do this when we clear the next marking bitmap in 1370 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1371 // objects marked during a full GC against the previous bitmap. 1372 // But we need to clear it before calling check_bitmaps below since 1373 // the full GC has compacted objects and updated TAMS but not updated 1374 // the prev bitmap. 1375 if (G1VerifyBitmaps) { 1376 GCTraceTime(Debug, gc)("Clear Bitmap for Verification"); 1377 _cm->clear_prev_bitmap(workers()); 1378 } 1379 _verifier->check_bitmaps("Full GC End"); 1380 1381 // Start a new incremental collection set for the next pause 1382 collection_set()->start_incremental_building(); 1383 1384 clear_cset_fast_test(); 1385 1386 _allocator->init_mutator_alloc_region(); 1387 1388 g1_policy()->record_full_collection_end(); 1389 1390 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1391 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1392 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1393 // before any GC notifications are raised. 1394 g1mm()->update_sizes(); 1395 1396 gc_epilogue(true); 1397 1398 heap_transition.print(); 1399 1400 print_heap_after_gc(); 1401 print_heap_regions(); 1402 trace_heap_after_gc(gc_tracer); 1403 1404 post_full_gc_dump(gc_timer); 1405 } 1406 1407 gc_timer->register_gc_end(); 1408 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1409 } 1410 1411 return true; 1412 } 1413 1414 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1415 // Currently, there is no facility in the do_full_collection(bool) API to notify 1416 // the caller that the collection did not succeed (e.g., because it was locked 1417 // out by the GC locker). So, right now, we'll ignore the return value. 1418 bool dummy = do_full_collection(true, /* explicit_gc */ 1419 clear_all_soft_refs); 1420 } 1421 1422 void G1CollectedHeap::resize_if_necessary_after_full_collection() { 1423 // Include bytes that will be pre-allocated to support collections, as "used". 1424 const size_t used_after_gc = used(); 1425 const size_t capacity_after_gc = capacity(); 1426 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1427 1428 // This is enforced in arguments.cpp. 1429 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1430 "otherwise the code below doesn't make sense"); 1431 1432 // We don't have floating point command-line arguments 1433 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1434 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1435 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1436 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1437 1438 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1439 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1440 1441 // We have to be careful here as these two calculations can overflow 1442 // 32-bit size_t's. 1443 double used_after_gc_d = (double) used_after_gc; 1444 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1445 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1446 1447 // Let's make sure that they are both under the max heap size, which 1448 // by default will make them fit into a size_t. 1449 double desired_capacity_upper_bound = (double) max_heap_size; 1450 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1451 desired_capacity_upper_bound); 1452 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1453 desired_capacity_upper_bound); 1454 1455 // We can now safely turn them into size_t's. 1456 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1457 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1458 1459 // This assert only makes sense here, before we adjust them 1460 // with respect to the min and max heap size. 1461 assert(minimum_desired_capacity <= maximum_desired_capacity, 1462 "minimum_desired_capacity = " SIZE_FORMAT ", " 1463 "maximum_desired_capacity = " SIZE_FORMAT, 1464 minimum_desired_capacity, maximum_desired_capacity); 1465 1466 // Should not be greater than the heap max size. No need to adjust 1467 // it with respect to the heap min size as it's a lower bound (i.e., 1468 // we'll try to make the capacity larger than it, not smaller). 1469 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1470 // Should not be less than the heap min size. No need to adjust it 1471 // with respect to the heap max size as it's an upper bound (i.e., 1472 // we'll try to make the capacity smaller than it, not greater). 1473 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1474 1475 if (capacity_after_gc < minimum_desired_capacity) { 1476 // Don't expand unless it's significant 1477 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1478 1479 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). " 1480 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1481 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio); 1482 1483 expand(expand_bytes, _workers); 1484 1485 // No expansion, now see if we want to shrink 1486 } else if (capacity_after_gc > maximum_desired_capacity) { 1487 // Capacity too large, compute shrinking size 1488 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1489 1490 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). " 1491 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1492 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio); 1493 1494 shrink(shrink_bytes); 1495 } 1496 } 1497 1498 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1499 AllocationContext_t context, 1500 bool do_gc, 1501 bool clear_all_soft_refs, 1502 bool expect_null_mutator_alloc_region, 1503 bool* gc_succeeded) { 1504 *gc_succeeded = true; 1505 // Let's attempt the allocation first. 1506 HeapWord* result = 1507 attempt_allocation_at_safepoint(word_size, 1508 context, 1509 expect_null_mutator_alloc_region); 1510 if (result != NULL) { 1511 assert(*gc_succeeded, "sanity"); 1512 return result; 1513 } 1514 1515 // In a G1 heap, we're supposed to keep allocation from failing by 1516 // incremental pauses. Therefore, at least for now, we'll favor 1517 // expansion over collection. (This might change in the future if we can 1518 // do something smarter than full collection to satisfy a failed alloc.) 1519 result = expand_and_allocate(word_size, context); 1520 if (result != NULL) { 1521 assert(*gc_succeeded, "sanity"); 1522 return result; 1523 } 1524 1525 if (do_gc) { 1526 // Expansion didn't work, we'll try to do a Full GC. 1527 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1528 clear_all_soft_refs); 1529 } 1530 1531 return NULL; 1532 } 1533 1534 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1535 AllocationContext_t context, 1536 bool* succeeded) { 1537 assert_at_safepoint(true /* should_be_vm_thread */); 1538 1539 // Attempts to allocate followed by Full GC. 1540 HeapWord* result = 1541 satisfy_failed_allocation_helper(word_size, 1542 context, 1543 true, /* do_gc */ 1544 false, /* clear_all_soft_refs */ 1545 false, /* expect_null_mutator_alloc_region */ 1546 succeeded); 1547 1548 if (result != NULL || !*succeeded) { 1549 return result; 1550 } 1551 1552 // Attempts to allocate followed by Full GC that will collect all soft references. 1553 result = satisfy_failed_allocation_helper(word_size, 1554 context, 1555 true, /* do_gc */ 1556 true, /* clear_all_soft_refs */ 1557 true, /* expect_null_mutator_alloc_region */ 1558 succeeded); 1559 1560 if (result != NULL || !*succeeded) { 1561 return result; 1562 } 1563 1564 // Attempts to allocate, no GC 1565 result = satisfy_failed_allocation_helper(word_size, 1566 context, 1567 false, /* do_gc */ 1568 false, /* clear_all_soft_refs */ 1569 true, /* expect_null_mutator_alloc_region */ 1570 succeeded); 1571 1572 if (result != NULL) { 1573 assert(*succeeded, "sanity"); 1574 return result; 1575 } 1576 1577 assert(!collector_policy()->should_clear_all_soft_refs(), 1578 "Flag should have been handled and cleared prior to this point"); 1579 1580 // What else? We might try synchronous finalization later. If the total 1581 // space available is large enough for the allocation, then a more 1582 // complete compaction phase than we've tried so far might be 1583 // appropriate. 1584 assert(*succeeded, "sanity"); 1585 return NULL; 1586 } 1587 1588 // Attempting to expand the heap sufficiently 1589 // to support an allocation of the given "word_size". If 1590 // successful, perform the allocation and return the address of the 1591 // allocated block, or else "NULL". 1592 1593 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1594 assert_at_safepoint(true /* should_be_vm_thread */); 1595 1596 _verifier->verify_region_sets_optional(); 1597 1598 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1599 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1600 word_size * HeapWordSize); 1601 1602 1603 if (expand(expand_bytes, _workers)) { 1604 _hrm.verify_optional(); 1605 _verifier->verify_region_sets_optional(); 1606 return attempt_allocation_at_safepoint(word_size, 1607 context, 1608 false /* expect_null_mutator_alloc_region */); 1609 } 1610 return NULL; 1611 } 1612 1613 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1614 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1615 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1616 HeapRegion::GrainBytes); 1617 1618 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B", 1619 expand_bytes, aligned_expand_bytes); 1620 1621 if (is_maximal_no_gc()) { 1622 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1623 return false; 1624 } 1625 1626 double expand_heap_start_time_sec = os::elapsedTime(); 1627 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1628 assert(regions_to_expand > 0, "Must expand by at least one region"); 1629 1630 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers); 1631 if (expand_time_ms != NULL) { 1632 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1633 } 1634 1635 if (expanded_by > 0) { 1636 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1637 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1638 g1_policy()->record_new_heap_size(num_regions()); 1639 } else { 1640 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1641 1642 // The expansion of the virtual storage space was unsuccessful. 1643 // Let's see if it was because we ran out of swap. 1644 if (G1ExitOnExpansionFailure && 1645 _hrm.available() >= regions_to_expand) { 1646 // We had head room... 1647 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1648 } 1649 } 1650 return regions_to_expand > 0; 1651 } 1652 1653 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1654 size_t aligned_shrink_bytes = 1655 ReservedSpace::page_align_size_down(shrink_bytes); 1656 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1657 HeapRegion::GrainBytes); 1658 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1659 1660 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1661 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1662 1663 1664 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", 1665 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1666 if (num_regions_removed > 0) { 1667 g1_policy()->record_new_heap_size(num_regions()); 1668 } else { 1669 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1670 } 1671 } 1672 1673 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1674 _verifier->verify_region_sets_optional(); 1675 1676 // We should only reach here at the end of a Full GC which means we 1677 // should not not be holding to any GC alloc regions. The method 1678 // below will make sure of that and do any remaining clean up. 1679 _allocator->abandon_gc_alloc_regions(); 1680 1681 // Instead of tearing down / rebuilding the free lists here, we 1682 // could instead use the remove_all_pending() method on free_list to 1683 // remove only the ones that we need to remove. 1684 tear_down_region_sets(true /* free_list_only */); 1685 shrink_helper(shrink_bytes); 1686 rebuild_region_sets(true /* free_list_only */); 1687 1688 _hrm.verify_optional(); 1689 _verifier->verify_region_sets_optional(); 1690 } 1691 1692 // Public methods. 1693 1694 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) : 1695 CollectedHeap(), 1696 _collector_policy(collector_policy), 1697 _g1_policy(create_g1_policy()), 1698 _collection_set(this, _g1_policy), 1699 _dirty_card_queue_set(false), 1700 _is_alive_closure_cm(this), 1701 _is_alive_closure_stw(this), 1702 _ref_processor_cm(NULL), 1703 _ref_processor_stw(NULL), 1704 _bot(NULL), 1705 _hot_card_cache(NULL), 1706 _g1_rem_set(NULL), 1707 _cg1r(NULL), 1708 _g1mm(NULL), 1709 _refine_cte_cl(NULL), 1710 _preserved_marks_set(true /* in_c_heap */), 1711 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1712 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1713 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1714 _humongous_reclaim_candidates(), 1715 _has_humongous_reclaim_candidates(false), 1716 _archive_allocator(NULL), 1717 _free_regions_coming(false), 1718 _gc_time_stamp(0), 1719 _summary_bytes_used(0), 1720 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1721 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1722 _expand_heap_after_alloc_failure(true), 1723 _old_marking_cycles_started(0), 1724 _old_marking_cycles_completed(0), 1725 _in_cset_fast_test(), 1726 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1727 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()) { 1728 1729 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1730 /* are_GC_task_threads */true, 1731 /* are_ConcurrentGC_threads */false); 1732 _workers->initialize_workers(); 1733 _verifier = new G1HeapVerifier(this); 1734 1735 _allocator = G1Allocator::create_allocator(this); 1736 1737 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics()); 1738 1739 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1740 1741 // Override the default _filler_array_max_size so that no humongous filler 1742 // objects are created. 1743 _filler_array_max_size = _humongous_object_threshold_in_words; 1744 1745 uint n_queues = ParallelGCThreads; 1746 _task_queues = new RefToScanQueueSet(n_queues); 1747 1748 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1749 1750 for (uint i = 0; i < n_queues; i++) { 1751 RefToScanQueue* q = new RefToScanQueue(); 1752 q->initialize(); 1753 _task_queues->register_queue(i, q); 1754 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1755 } 1756 1757 // Initialize the G1EvacuationFailureALot counters and flags. 1758 NOT_PRODUCT(reset_evacuation_should_fail();) 1759 1760 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1761 } 1762 1763 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1764 size_t size, 1765 size_t translation_factor) { 1766 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1767 // Allocate a new reserved space, preferring to use large pages. 1768 ReservedSpace rs(size, preferred_page_size); 1769 G1RegionToSpaceMapper* result = 1770 G1RegionToSpaceMapper::create_mapper(rs, 1771 size, 1772 rs.alignment(), 1773 HeapRegion::GrainBytes, 1774 translation_factor, 1775 mtGC); 1776 1777 os::trace_page_sizes_for_requested_size(description, 1778 size, 1779 preferred_page_size, 1780 rs.alignment(), 1781 rs.base(), 1782 rs.size()); 1783 1784 return result; 1785 } 1786 1787 jint G1CollectedHeap::initialize() { 1788 CollectedHeap::pre_initialize(); 1789 os::enable_vtime(); 1790 1791 // Necessary to satisfy locking discipline assertions. 1792 1793 MutexLocker x(Heap_lock); 1794 1795 // While there are no constraints in the GC code that HeapWordSize 1796 // be any particular value, there are multiple other areas in the 1797 // system which believe this to be true (e.g. oop->object_size in some 1798 // cases incorrectly returns the size in wordSize units rather than 1799 // HeapWordSize). 1800 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1801 1802 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1803 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1804 size_t heap_alignment = collector_policy()->heap_alignment(); 1805 1806 // Ensure that the sizes are properly aligned. 1807 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1808 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1809 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1810 1811 _refine_cte_cl = new RefineCardTableEntryClosure(); 1812 1813 jint ecode = JNI_OK; 1814 _cg1r = ConcurrentG1Refine::create(_refine_cte_cl, &ecode); 1815 if (_cg1r == NULL) { 1816 return ecode; 1817 } 1818 1819 // Reserve the maximum. 1820 1821 // When compressed oops are enabled, the preferred heap base 1822 // is calculated by subtracting the requested size from the 1823 // 32Gb boundary and using the result as the base address for 1824 // heap reservation. If the requested size is not aligned to 1825 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1826 // into the ReservedHeapSpace constructor) then the actual 1827 // base of the reserved heap may end up differing from the 1828 // address that was requested (i.e. the preferred heap base). 1829 // If this happens then we could end up using a non-optimal 1830 // compressed oops mode. 1831 1832 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1833 heap_alignment); 1834 1835 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1836 1837 // Create the barrier set for the entire reserved region. 1838 G1SATBCardTableLoggingModRefBS* bs 1839 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 1840 bs->initialize(); 1841 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 1842 set_barrier_set(bs); 1843 1844 // Create the hot card cache. 1845 _hot_card_cache = new G1HotCardCache(this); 1846 1847 // Also create a G1 rem set. 1848 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache); 1849 1850 // Carve out the G1 part of the heap. 1851 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1852 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 1853 G1RegionToSpaceMapper* heap_storage = 1854 G1RegionToSpaceMapper::create_mapper(g1_rs, 1855 g1_rs.size(), 1856 page_size, 1857 HeapRegion::GrainBytes, 1858 1, 1859 mtJavaHeap); 1860 os::trace_page_sizes("Heap", 1861 collector_policy()->min_heap_byte_size(), 1862 max_byte_size, 1863 page_size, 1864 heap_rs.base(), 1865 heap_rs.size()); 1866 heap_storage->set_mapping_changed_listener(&_listener); 1867 1868 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1869 G1RegionToSpaceMapper* bot_storage = 1870 create_aux_memory_mapper("Block Offset Table", 1871 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1872 G1BlockOffsetTable::heap_map_factor()); 1873 1874 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 1875 G1RegionToSpaceMapper* cardtable_storage = 1876 create_aux_memory_mapper("Card Table", 1877 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize), 1878 G1SATBCardTableLoggingModRefBS::heap_map_factor()); 1879 1880 G1RegionToSpaceMapper* card_counts_storage = 1881 create_aux_memory_mapper("Card Counts Table", 1882 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1883 G1CardCounts::heap_map_factor()); 1884 1885 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1886 G1RegionToSpaceMapper* prev_bitmap_storage = 1887 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1888 G1RegionToSpaceMapper* next_bitmap_storage = 1889 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1890 1891 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1892 g1_barrier_set()->initialize(cardtable_storage); 1893 // Do later initialization work for concurrent refinement. 1894 _hot_card_cache->initialize(card_counts_storage); 1895 1896 // 6843694 - ensure that the maximum region index can fit 1897 // in the remembered set structures. 1898 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1899 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1900 1901 g1_rem_set()->initialize(max_capacity(), max_regions()); 1902 1903 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1904 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1905 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1906 "too many cards per region"); 1907 1908 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1909 1910 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1911 1912 { 1913 HeapWord* start = _hrm.reserved().start(); 1914 HeapWord* end = _hrm.reserved().end(); 1915 size_t granularity = HeapRegion::GrainBytes; 1916 1917 _in_cset_fast_test.initialize(start, end, granularity); 1918 _humongous_reclaim_candidates.initialize(start, end, granularity); 1919 } 1920 1921 // Create the G1ConcurrentMark data structure and thread. 1922 // (Must do this late, so that "max_regions" is defined.) 1923 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1924 if (_cm == NULL || !_cm->completed_initialization()) { 1925 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1926 return JNI_ENOMEM; 1927 } 1928 _cmThread = _cm->cmThread(); 1929 1930 // Now expand into the initial heap size. 1931 if (!expand(init_byte_size, _workers)) { 1932 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1933 return JNI_ENOMEM; 1934 } 1935 1936 // Perform any initialization actions delegated to the policy. 1937 g1_policy()->init(this, &_collection_set); 1938 1939 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 1940 SATB_Q_FL_lock, 1941 G1SATBProcessCompletedThreshold, 1942 Shared_SATB_Q_lock); 1943 1944 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 1945 DirtyCardQ_CBL_mon, 1946 DirtyCardQ_FL_lock, 1947 (int)concurrent_g1_refine()->yellow_zone(), 1948 (int)concurrent_g1_refine()->red_zone(), 1949 Shared_DirtyCardQ_lock, 1950 NULL, // fl_owner 1951 true); // init_free_ids 1952 1953 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 1954 DirtyCardQ_CBL_mon, 1955 DirtyCardQ_FL_lock, 1956 -1, // never trigger processing 1957 -1, // no limit on length 1958 Shared_DirtyCardQ_lock, 1959 &JavaThread::dirty_card_queue_set()); 1960 1961 // Here we allocate the dummy HeapRegion that is required by the 1962 // G1AllocRegion class. 1963 HeapRegion* dummy_region = _hrm.get_dummy_region(); 1964 1965 // We'll re-use the same region whether the alloc region will 1966 // require BOT updates or not and, if it doesn't, then a non-young 1967 // region will complain that it cannot support allocations without 1968 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1969 dummy_region->set_eden(); 1970 // Make sure it's full. 1971 dummy_region->set_top(dummy_region->end()); 1972 G1AllocRegion::setup(this, dummy_region); 1973 1974 _allocator->init_mutator_alloc_region(); 1975 1976 // Do create of the monitoring and management support so that 1977 // values in the heap have been properly initialized. 1978 _g1mm = new G1MonitoringSupport(this); 1979 1980 G1StringDedup::initialize(); 1981 1982 _preserved_marks_set.init(ParallelGCThreads); 1983 1984 _collection_set.initialize(max_regions()); 1985 1986 return JNI_OK; 1987 } 1988 1989 void G1CollectedHeap::stop() { 1990 // Stop all concurrent threads. We do this to make sure these threads 1991 // do not continue to execute and access resources (e.g. logging) 1992 // that are destroyed during shutdown. 1993 _cg1r->stop(); 1994 _cmThread->stop(); 1995 if (G1StringDedup::is_enabled()) { 1996 G1StringDedup::stop(); 1997 } 1998 } 1999 2000 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2001 return HeapRegion::max_region_size(); 2002 } 2003 2004 void G1CollectedHeap::post_initialize() { 2005 ref_processing_init(); 2006 } 2007 2008 void G1CollectedHeap::ref_processing_init() { 2009 // Reference processing in G1 currently works as follows: 2010 // 2011 // * There are two reference processor instances. One is 2012 // used to record and process discovered references 2013 // during concurrent marking; the other is used to 2014 // record and process references during STW pauses 2015 // (both full and incremental). 2016 // * Both ref processors need to 'span' the entire heap as 2017 // the regions in the collection set may be dotted around. 2018 // 2019 // * For the concurrent marking ref processor: 2020 // * Reference discovery is enabled at initial marking. 2021 // * Reference discovery is disabled and the discovered 2022 // references processed etc during remarking. 2023 // * Reference discovery is MT (see below). 2024 // * Reference discovery requires a barrier (see below). 2025 // * Reference processing may or may not be MT 2026 // (depending on the value of ParallelRefProcEnabled 2027 // and ParallelGCThreads). 2028 // * A full GC disables reference discovery by the CM 2029 // ref processor and abandons any entries on it's 2030 // discovered lists. 2031 // 2032 // * For the STW processor: 2033 // * Non MT discovery is enabled at the start of a full GC. 2034 // * Processing and enqueueing during a full GC is non-MT. 2035 // * During a full GC, references are processed after marking. 2036 // 2037 // * Discovery (may or may not be MT) is enabled at the start 2038 // of an incremental evacuation pause. 2039 // * References are processed near the end of a STW evacuation pause. 2040 // * For both types of GC: 2041 // * Discovery is atomic - i.e. not concurrent. 2042 // * Reference discovery will not need a barrier. 2043 2044 MemRegion mr = reserved_region(); 2045 2046 // Concurrent Mark ref processor 2047 _ref_processor_cm = 2048 new ReferenceProcessor(mr, // span 2049 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2050 // mt processing 2051 ParallelGCThreads, 2052 // degree of mt processing 2053 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2054 // mt discovery 2055 MAX2(ParallelGCThreads, ConcGCThreads), 2056 // degree of mt discovery 2057 false, 2058 // Reference discovery is not atomic 2059 &_is_alive_closure_cm); 2060 // is alive closure 2061 // (for efficiency/performance) 2062 2063 // STW ref processor 2064 _ref_processor_stw = 2065 new ReferenceProcessor(mr, // span 2066 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2067 // mt processing 2068 ParallelGCThreads, 2069 // degree of mt processing 2070 (ParallelGCThreads > 1), 2071 // mt discovery 2072 ParallelGCThreads, 2073 // degree of mt discovery 2074 true, 2075 // Reference discovery is atomic 2076 &_is_alive_closure_stw); 2077 // is alive closure 2078 // (for efficiency/performance) 2079 } 2080 2081 CollectorPolicy* G1CollectedHeap::collector_policy() const { 2082 return _collector_policy; 2083 } 2084 2085 size_t G1CollectedHeap::capacity() const { 2086 return _hrm.length() * HeapRegion::GrainBytes; 2087 } 2088 2089 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2090 hr->reset_gc_time_stamp(); 2091 } 2092 2093 #ifndef PRODUCT 2094 2095 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2096 private: 2097 unsigned _gc_time_stamp; 2098 bool _failures; 2099 2100 public: 2101 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2102 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2103 2104 virtual bool doHeapRegion(HeapRegion* hr) { 2105 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2106 if (_gc_time_stamp != region_gc_time_stamp) { 2107 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr), 2108 region_gc_time_stamp, _gc_time_stamp); 2109 _failures = true; 2110 } 2111 return false; 2112 } 2113 2114 bool failures() { return _failures; } 2115 }; 2116 2117 void G1CollectedHeap::check_gc_time_stamps() { 2118 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2119 heap_region_iterate(&cl); 2120 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2121 } 2122 #endif // PRODUCT 2123 2124 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) { 2125 _hot_card_cache->drain(cl, worker_i); 2126 } 2127 2128 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) { 2129 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2130 size_t n_completed_buffers = 0; 2131 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2132 n_completed_buffers++; 2133 } 2134 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 2135 dcqs.clear_n_completed_buffers(); 2136 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2137 } 2138 2139 // Computes the sum of the storage used by the various regions. 2140 size_t G1CollectedHeap::used() const { 2141 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 2142 if (_archive_allocator != NULL) { 2143 result += _archive_allocator->used(); 2144 } 2145 return result; 2146 } 2147 2148 size_t G1CollectedHeap::used_unlocked() const { 2149 return _summary_bytes_used; 2150 } 2151 2152 class SumUsedClosure: public HeapRegionClosure { 2153 size_t _used; 2154 public: 2155 SumUsedClosure() : _used(0) {} 2156 bool doHeapRegion(HeapRegion* r) { 2157 _used += r->used(); 2158 return false; 2159 } 2160 size_t result() { return _used; } 2161 }; 2162 2163 size_t G1CollectedHeap::recalculate_used() const { 2164 double recalculate_used_start = os::elapsedTime(); 2165 2166 SumUsedClosure blk; 2167 heap_region_iterate(&blk); 2168 2169 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2170 return blk.result(); 2171 } 2172 2173 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 2174 switch (cause) { 2175 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2176 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 2177 case GCCause::_update_allocation_context_stats_inc: return true; 2178 case GCCause::_wb_conc_mark: return true; 2179 default : return false; 2180 } 2181 } 2182 2183 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2184 switch (cause) { 2185 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2186 case GCCause::_g1_humongous_allocation: return true; 2187 default: return is_user_requested_concurrent_full_gc(cause); 2188 } 2189 } 2190 2191 #ifndef PRODUCT 2192 void G1CollectedHeap::allocate_dummy_regions() { 2193 // Let's fill up most of the region 2194 size_t word_size = HeapRegion::GrainWords - 1024; 2195 // And as a result the region we'll allocate will be humongous. 2196 guarantee(is_humongous(word_size), "sanity"); 2197 2198 // _filler_array_max_size is set to humongous object threshold 2199 // but temporarily change it to use CollectedHeap::fill_with_object(). 2200 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2201 2202 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2203 // Let's use the existing mechanism for the allocation 2204 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2205 AllocationContext::system()); 2206 if (dummy_obj != NULL) { 2207 MemRegion mr(dummy_obj, word_size); 2208 CollectedHeap::fill_with_object(mr); 2209 } else { 2210 // If we can't allocate once, we probably cannot allocate 2211 // again. Let's get out of the loop. 2212 break; 2213 } 2214 } 2215 } 2216 #endif // !PRODUCT 2217 2218 void G1CollectedHeap::increment_old_marking_cycles_started() { 2219 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2220 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2221 "Wrong marking cycle count (started: %d, completed: %d)", 2222 _old_marking_cycles_started, _old_marking_cycles_completed); 2223 2224 _old_marking_cycles_started++; 2225 } 2226 2227 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2228 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2229 2230 // We assume that if concurrent == true, then the caller is a 2231 // concurrent thread that was joined the Suspendible Thread 2232 // Set. If there's ever a cheap way to check this, we should add an 2233 // assert here. 2234 2235 // Given that this method is called at the end of a Full GC or of a 2236 // concurrent cycle, and those can be nested (i.e., a Full GC can 2237 // interrupt a concurrent cycle), the number of full collections 2238 // completed should be either one (in the case where there was no 2239 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2240 // behind the number of full collections started. 2241 2242 // This is the case for the inner caller, i.e. a Full GC. 2243 assert(concurrent || 2244 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2245 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2246 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2247 "is inconsistent with _old_marking_cycles_completed = %u", 2248 _old_marking_cycles_started, _old_marking_cycles_completed); 2249 2250 // This is the case for the outer caller, i.e. the concurrent cycle. 2251 assert(!concurrent || 2252 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2253 "for outer caller (concurrent cycle): " 2254 "_old_marking_cycles_started = %u " 2255 "is inconsistent with _old_marking_cycles_completed = %u", 2256 _old_marking_cycles_started, _old_marking_cycles_completed); 2257 2258 _old_marking_cycles_completed += 1; 2259 2260 // We need to clear the "in_progress" flag in the CM thread before 2261 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2262 // is set) so that if a waiter requests another System.gc() it doesn't 2263 // incorrectly see that a marking cycle is still in progress. 2264 if (concurrent) { 2265 _cmThread->set_idle(); 2266 } 2267 2268 // This notify_all() will ensure that a thread that called 2269 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2270 // and it's waiting for a full GC to finish will be woken up. It is 2271 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2272 FullGCCount_lock->notify_all(); 2273 } 2274 2275 void G1CollectedHeap::collect(GCCause::Cause cause) { 2276 assert_heap_not_locked(); 2277 2278 uint gc_count_before; 2279 uint old_marking_count_before; 2280 uint full_gc_count_before; 2281 bool retry_gc; 2282 2283 do { 2284 retry_gc = false; 2285 2286 { 2287 MutexLocker ml(Heap_lock); 2288 2289 // Read the GC count while holding the Heap_lock 2290 gc_count_before = total_collections(); 2291 full_gc_count_before = total_full_collections(); 2292 old_marking_count_before = _old_marking_cycles_started; 2293 } 2294 2295 if (should_do_concurrent_full_gc(cause)) { 2296 // Schedule an initial-mark evacuation pause that will start a 2297 // concurrent cycle. We're setting word_size to 0 which means that 2298 // we are not requesting a post-GC allocation. 2299 VM_G1IncCollectionPause op(gc_count_before, 2300 0, /* word_size */ 2301 true, /* should_initiate_conc_mark */ 2302 g1_policy()->max_pause_time_ms(), 2303 cause); 2304 op.set_allocation_context(AllocationContext::current()); 2305 2306 VMThread::execute(&op); 2307 if (!op.pause_succeeded()) { 2308 if (old_marking_count_before == _old_marking_cycles_started) { 2309 retry_gc = op.should_retry_gc(); 2310 } else { 2311 // A Full GC happened while we were trying to schedule the 2312 // initial-mark GC. No point in starting a new cycle given 2313 // that the whole heap was collected anyway. 2314 } 2315 2316 if (retry_gc) { 2317 if (GCLocker::is_active_and_needs_gc()) { 2318 GCLocker::stall_until_clear(); 2319 } 2320 } 2321 } 2322 } else { 2323 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2324 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2325 2326 // Schedule a standard evacuation pause. We're setting word_size 2327 // to 0 which means that we are not requesting a post-GC allocation. 2328 VM_G1IncCollectionPause op(gc_count_before, 2329 0, /* word_size */ 2330 false, /* should_initiate_conc_mark */ 2331 g1_policy()->max_pause_time_ms(), 2332 cause); 2333 VMThread::execute(&op); 2334 } else { 2335 // Schedule a Full GC. 2336 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2337 VMThread::execute(&op); 2338 } 2339 } 2340 } while (retry_gc); 2341 } 2342 2343 bool G1CollectedHeap::is_in(const void* p) const { 2344 if (_hrm.reserved().contains(p)) { 2345 // Given that we know that p is in the reserved space, 2346 // heap_region_containing() should successfully 2347 // return the containing region. 2348 HeapRegion* hr = heap_region_containing(p); 2349 return hr->is_in(p); 2350 } else { 2351 return false; 2352 } 2353 } 2354 2355 #ifdef ASSERT 2356 bool G1CollectedHeap::is_in_exact(const void* p) const { 2357 bool contains = reserved_region().contains(p); 2358 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2359 if (contains && available) { 2360 return true; 2361 } else { 2362 return false; 2363 } 2364 } 2365 #endif 2366 2367 bool G1CollectedHeap::obj_in_cs(oop obj) { 2368 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj); 2369 return r != NULL && r->in_collection_set(); 2370 } 2371 2372 // Iteration functions. 2373 2374 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2375 2376 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2377 ExtendedOopClosure* _cl; 2378 public: 2379 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2380 bool doHeapRegion(HeapRegion* r) { 2381 if (!r->is_continues_humongous()) { 2382 r->oop_iterate(_cl); 2383 } 2384 return false; 2385 } 2386 }; 2387 2388 // Iterates an ObjectClosure over all objects within a HeapRegion. 2389 2390 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2391 ObjectClosure* _cl; 2392 public: 2393 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2394 bool doHeapRegion(HeapRegion* r) { 2395 if (!r->is_continues_humongous()) { 2396 r->object_iterate(_cl); 2397 } 2398 return false; 2399 } 2400 }; 2401 2402 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2403 IterateObjectClosureRegionClosure blk(cl); 2404 heap_region_iterate(&blk); 2405 } 2406 2407 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2408 _hrm.iterate(cl); 2409 } 2410 2411 void 2412 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, 2413 uint worker_id, 2414 HeapRegionClaimer *hrclaimer, 2415 bool concurrent) const { 2416 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); 2417 } 2418 2419 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2420 _collection_set.iterate(cl); 2421 } 2422 2423 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) { 2424 _collection_set.iterate_from(cl, worker_id, workers()->active_workers()); 2425 } 2426 2427 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2428 HeapRegion* result = _hrm.next_region_in_heap(from); 2429 while (result != NULL && result->is_pinned()) { 2430 result = _hrm.next_region_in_heap(result); 2431 } 2432 return result; 2433 } 2434 2435 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2436 HeapRegion* hr = heap_region_containing(addr); 2437 return hr->block_start(addr); 2438 } 2439 2440 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2441 HeapRegion* hr = heap_region_containing(addr); 2442 return hr->block_size(addr); 2443 } 2444 2445 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2446 HeapRegion* hr = heap_region_containing(addr); 2447 return hr->block_is_obj(addr); 2448 } 2449 2450 bool G1CollectedHeap::supports_tlab_allocation() const { 2451 return true; 2452 } 2453 2454 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2455 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2456 } 2457 2458 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2459 return _eden.length() * HeapRegion::GrainBytes; 2460 } 2461 2462 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2463 // must be equal to the humongous object limit. 2464 size_t G1CollectedHeap::max_tlab_size() const { 2465 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment); 2466 } 2467 2468 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2469 AllocationContext_t context = AllocationContext::current(); 2470 return _allocator->unsafe_max_tlab_alloc(context); 2471 } 2472 2473 size_t G1CollectedHeap::max_capacity() const { 2474 return _hrm.reserved().byte_size(); 2475 } 2476 2477 jlong G1CollectedHeap::millis_since_last_gc() { 2478 // See the notes in GenCollectedHeap::millis_since_last_gc() 2479 // for more information about the implementation. 2480 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2481 _g1_policy->collection_pause_end_millis(); 2482 if (ret_val < 0) { 2483 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2484 ". returning zero instead.", ret_val); 2485 return 0; 2486 } 2487 return ret_val; 2488 } 2489 2490 void G1CollectedHeap::prepare_for_verify() { 2491 _verifier->prepare_for_verify(); 2492 } 2493 2494 void G1CollectedHeap::verify(VerifyOption vo) { 2495 _verifier->verify(vo); 2496 } 2497 2498 class PrintRegionClosure: public HeapRegionClosure { 2499 outputStream* _st; 2500 public: 2501 PrintRegionClosure(outputStream* st) : _st(st) {} 2502 bool doHeapRegion(HeapRegion* r) { 2503 r->print_on(_st); 2504 return false; 2505 } 2506 }; 2507 2508 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2509 const HeapRegion* hr, 2510 const VerifyOption vo) const { 2511 switch (vo) { 2512 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2513 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2514 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive(); 2515 default: ShouldNotReachHere(); 2516 } 2517 return false; // keep some compilers happy 2518 } 2519 2520 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2521 const VerifyOption vo) const { 2522 switch (vo) { 2523 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2524 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2525 case VerifyOption_G1UseMarkWord: { 2526 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj); 2527 return !obj->is_gc_marked() && !hr->is_archive(); 2528 } 2529 default: ShouldNotReachHere(); 2530 } 2531 return false; // keep some compilers happy 2532 } 2533 2534 void G1CollectedHeap::print_heap_regions() const { 2535 Log(gc, heap, region) log; 2536 if (log.is_trace()) { 2537 ResourceMark rm; 2538 print_regions_on(log.trace_stream()); 2539 } 2540 } 2541 2542 void G1CollectedHeap::print_on(outputStream* st) const { 2543 st->print(" %-20s", "garbage-first heap"); 2544 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2545 capacity()/K, used_unlocked()/K); 2546 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")", 2547 p2i(_hrm.reserved().start()), 2548 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords), 2549 p2i(_hrm.reserved().end())); 2550 st->cr(); 2551 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2552 uint young_regions = young_regions_count(); 2553 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2554 (size_t) young_regions * HeapRegion::GrainBytes / K); 2555 uint survivor_regions = survivor_regions_count(); 2556 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2557 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2558 st->cr(); 2559 MetaspaceAux::print_on(st); 2560 } 2561 2562 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2563 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2564 "HS=humongous(starts), HC=humongous(continues), " 2565 "CS=collection set, F=free, A=archive, TS=gc time stamp, " 2566 "AC=allocation context, " 2567 "TAMS=top-at-mark-start (previous, next)"); 2568 PrintRegionClosure blk(st); 2569 heap_region_iterate(&blk); 2570 } 2571 2572 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2573 print_on(st); 2574 2575 // Print the per-region information. 2576 print_regions_on(st); 2577 } 2578 2579 void G1CollectedHeap::print_on_error(outputStream* st) const { 2580 this->CollectedHeap::print_on_error(st); 2581 2582 if (_cm != NULL) { 2583 st->cr(); 2584 _cm->print_on_error(st); 2585 } 2586 } 2587 2588 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2589 workers()->print_worker_threads_on(st); 2590 _cmThread->print_on(st); 2591 st->cr(); 2592 _cm->print_worker_threads_on(st); 2593 _cg1r->print_worker_threads_on(st); // also prints the sample thread 2594 if (G1StringDedup::is_enabled()) { 2595 G1StringDedup::print_worker_threads_on(st); 2596 } 2597 } 2598 2599 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2600 workers()->threads_do(tc); 2601 tc->do_thread(_cmThread); 2602 _cm->threads_do(tc); 2603 _cg1r->threads_do(tc); // also iterates over the sample thread 2604 if (G1StringDedup::is_enabled()) { 2605 G1StringDedup::threads_do(tc); 2606 } 2607 } 2608 2609 void G1CollectedHeap::print_tracing_info() const { 2610 g1_rem_set()->print_summary_info(); 2611 concurrent_mark()->print_summary_info(); 2612 } 2613 2614 #ifndef PRODUCT 2615 // Helpful for debugging RSet issues. 2616 2617 class PrintRSetsClosure : public HeapRegionClosure { 2618 private: 2619 const char* _msg; 2620 size_t _occupied_sum; 2621 2622 public: 2623 bool doHeapRegion(HeapRegion* r) { 2624 HeapRegionRemSet* hrrs = r->rem_set(); 2625 size_t occupied = hrrs->occupied(); 2626 _occupied_sum += occupied; 2627 2628 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2629 if (occupied == 0) { 2630 tty->print_cr(" RSet is empty"); 2631 } else { 2632 hrrs->print(); 2633 } 2634 tty->print_cr("----------"); 2635 return false; 2636 } 2637 2638 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2639 tty->cr(); 2640 tty->print_cr("========================================"); 2641 tty->print_cr("%s", msg); 2642 tty->cr(); 2643 } 2644 2645 ~PrintRSetsClosure() { 2646 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2647 tty->print_cr("========================================"); 2648 tty->cr(); 2649 } 2650 }; 2651 2652 void G1CollectedHeap::print_cset_rsets() { 2653 PrintRSetsClosure cl("Printing CSet RSets"); 2654 collection_set_iterate(&cl); 2655 } 2656 2657 void G1CollectedHeap::print_all_rsets() { 2658 PrintRSetsClosure cl("Printing All RSets");; 2659 heap_region_iterate(&cl); 2660 } 2661 #endif // PRODUCT 2662 2663 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2664 2665 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes; 2666 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes; 2667 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2668 2669 size_t eden_capacity_bytes = 2670 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2671 2672 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2673 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2674 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2675 } 2676 2677 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2678 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2679 stats->unused(), stats->used(), stats->region_end_waste(), 2680 stats->regions_filled(), stats->direct_allocated(), 2681 stats->failure_used(), stats->failure_waste()); 2682 } 2683 2684 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2685 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2686 gc_tracer->report_gc_heap_summary(when, heap_summary); 2687 2688 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2689 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2690 } 2691 2692 G1CollectedHeap* G1CollectedHeap::heap() { 2693 CollectedHeap* heap = Universe::heap(); 2694 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2695 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); 2696 return (G1CollectedHeap*)heap; 2697 } 2698 2699 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 2700 // always_do_update_barrier = false; 2701 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2702 // Fill TLAB's and such 2703 accumulate_statistics_all_tlabs(); 2704 ensure_parsability(true); 2705 2706 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2707 } 2708 2709 void G1CollectedHeap::gc_epilogue(bool full) { 2710 // we are at the end of the GC. Total collections has already been increased. 2711 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2712 2713 // FIXME: what is this about? 2714 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2715 // is set. 2716 #if defined(COMPILER2) || INCLUDE_JVMCI 2717 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2718 #endif 2719 // always_do_update_barrier = true; 2720 2721 resize_all_tlabs(); 2722 allocation_context_stats().update(full); 2723 2724 // We have just completed a GC. Update the soft reference 2725 // policy with the new heap occupancy 2726 Universe::update_heap_info_at_gc(); 2727 } 2728 2729 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2730 uint gc_count_before, 2731 bool* succeeded, 2732 GCCause::Cause gc_cause) { 2733 assert_heap_not_locked_and_not_at_safepoint(); 2734 VM_G1IncCollectionPause op(gc_count_before, 2735 word_size, 2736 false, /* should_initiate_conc_mark */ 2737 g1_policy()->max_pause_time_ms(), 2738 gc_cause); 2739 2740 op.set_allocation_context(AllocationContext::current()); 2741 VMThread::execute(&op); 2742 2743 HeapWord* result = op.result(); 2744 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 2745 assert(result == NULL || ret_succeeded, 2746 "the result should be NULL if the VM did not succeed"); 2747 *succeeded = ret_succeeded; 2748 2749 assert_heap_not_locked(); 2750 return result; 2751 } 2752 2753 void 2754 G1CollectedHeap::doConcurrentMark() { 2755 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 2756 if (!_cmThread->in_progress()) { 2757 _cmThread->set_started(); 2758 CGC_lock->notify(); 2759 } 2760 } 2761 2762 size_t G1CollectedHeap::pending_card_num() { 2763 size_t extra_cards = 0; 2764 JavaThread *curr = Threads::first(); 2765 while (curr != NULL) { 2766 DirtyCardQueue& dcq = curr->dirty_card_queue(); 2767 extra_cards += dcq.size(); 2768 curr = curr->next(); 2769 } 2770 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2771 size_t buffer_size = dcqs.buffer_size(); 2772 size_t buffer_num = dcqs.completed_buffers_num(); 2773 2774 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 2775 // in bytes - not the number of 'entries'. We need to convert 2776 // into a number of cards. 2777 return (buffer_size * buffer_num + extra_cards) / oopSize; 2778 } 2779 2780 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 2781 private: 2782 size_t _total_humongous; 2783 size_t _candidate_humongous; 2784 2785 DirtyCardQueue _dcq; 2786 2787 // We don't nominate objects with many remembered set entries, on 2788 // the assumption that such objects are likely still live. 2789 bool is_remset_small(HeapRegion* region) const { 2790 HeapRegionRemSet* const rset = region->rem_set(); 2791 return G1EagerReclaimHumongousObjectsWithStaleRefs 2792 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) 2793 : rset->is_empty(); 2794 } 2795 2796 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { 2797 assert(region->is_starts_humongous(), "Must start a humongous object"); 2798 2799 oop obj = oop(region->bottom()); 2800 2801 // Dead objects cannot be eager reclaim candidates. Due to class 2802 // unloading it is unsafe to query their classes so we return early. 2803 if (heap->is_obj_dead(obj, region)) { 2804 return false; 2805 } 2806 2807 // Candidate selection must satisfy the following constraints 2808 // while concurrent marking is in progress: 2809 // 2810 // * In order to maintain SATB invariants, an object must not be 2811 // reclaimed if it was allocated before the start of marking and 2812 // has not had its references scanned. Such an object must have 2813 // its references (including type metadata) scanned to ensure no 2814 // live objects are missed by the marking process. Objects 2815 // allocated after the start of concurrent marking don't need to 2816 // be scanned. 2817 // 2818 // * An object must not be reclaimed if it is on the concurrent 2819 // mark stack. Objects allocated after the start of concurrent 2820 // marking are never pushed on the mark stack. 2821 // 2822 // Nominating only objects allocated after the start of concurrent 2823 // marking is sufficient to meet both constraints. This may miss 2824 // some objects that satisfy the constraints, but the marking data 2825 // structures don't support efficiently performing the needed 2826 // additional tests or scrubbing of the mark stack. 2827 // 2828 // However, we presently only nominate is_typeArray() objects. 2829 // A humongous object containing references induces remembered 2830 // set entries on other regions. In order to reclaim such an 2831 // object, those remembered sets would need to be cleaned up. 2832 // 2833 // We also treat is_typeArray() objects specially, allowing them 2834 // to be reclaimed even if allocated before the start of 2835 // concurrent mark. For this we rely on mark stack insertion to 2836 // exclude is_typeArray() objects, preventing reclaiming an object 2837 // that is in the mark stack. We also rely on the metadata for 2838 // such objects to be built-in and so ensured to be kept live. 2839 // Frequent allocation and drop of large binary blobs is an 2840 // important use case for eager reclaim, and this special handling 2841 // may reduce needed headroom. 2842 2843 return obj->is_typeArray() && is_remset_small(region); 2844 } 2845 2846 public: 2847 RegisterHumongousWithInCSetFastTestClosure() 2848 : _total_humongous(0), 2849 _candidate_humongous(0), 2850 _dcq(&JavaThread::dirty_card_queue_set()) { 2851 } 2852 2853 virtual bool doHeapRegion(HeapRegion* r) { 2854 if (!r->is_starts_humongous()) { 2855 return false; 2856 } 2857 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2858 2859 bool is_candidate = humongous_region_is_candidate(g1h, r); 2860 uint rindex = r->hrm_index(); 2861 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2862 if (is_candidate) { 2863 _candidate_humongous++; 2864 g1h->register_humongous_region_with_cset(rindex); 2865 // Is_candidate already filters out humongous object with large remembered sets. 2866 // If we have a humongous object with a few remembered sets, we simply flush these 2867 // remembered set entries into the DCQS. That will result in automatic 2868 // re-evaluation of their remembered set entries during the following evacuation 2869 // phase. 2870 if (!r->rem_set()->is_empty()) { 2871 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 2872 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 2873 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 2874 HeapRegionRemSetIterator hrrs(r->rem_set()); 2875 size_t card_index; 2876 while (hrrs.has_next(card_index)) { 2877 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 2878 // The remembered set might contain references to already freed 2879 // regions. Filter out such entries to avoid failing card table 2880 // verification. 2881 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) { 2882 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 2883 *card_ptr = CardTableModRefBS::dirty_card_val(); 2884 _dcq.enqueue(card_ptr); 2885 } 2886 } 2887 } 2888 assert(hrrs.n_yielded() == r->rem_set()->occupied(), 2889 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", 2890 hrrs.n_yielded(), r->rem_set()->occupied()); 2891 r->rem_set()->clear_locked(); 2892 } 2893 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 2894 } 2895 _total_humongous++; 2896 2897 return false; 2898 } 2899 2900 size_t total_humongous() const { return _total_humongous; } 2901 size_t candidate_humongous() const { return _candidate_humongous; } 2902 2903 void flush_rem_set_entries() { _dcq.flush(); } 2904 }; 2905 2906 void G1CollectedHeap::register_humongous_regions_with_cset() { 2907 if (!G1EagerReclaimHumongousObjects) { 2908 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 2909 return; 2910 } 2911 double time = os::elapsed_counter(); 2912 2913 // Collect reclaim candidate information and register candidates with cset. 2914 RegisterHumongousWithInCSetFastTestClosure cl; 2915 heap_region_iterate(&cl); 2916 2917 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 2918 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 2919 cl.total_humongous(), 2920 cl.candidate_humongous()); 2921 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2922 2923 // Finally flush all remembered set entries to re-check into the global DCQS. 2924 cl.flush_rem_set_entries(); 2925 } 2926 2927 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2928 public: 2929 bool doHeapRegion(HeapRegion* hr) { 2930 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2931 hr->verify_rem_set(); 2932 } 2933 return false; 2934 } 2935 }; 2936 2937 uint G1CollectedHeap::num_task_queues() const { 2938 return _task_queues->size(); 2939 } 2940 2941 #if TASKQUEUE_STATS 2942 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2943 st->print_raw_cr("GC Task Stats"); 2944 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2945 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2946 } 2947 2948 void G1CollectedHeap::print_taskqueue_stats() const { 2949 if (!log_is_enabled(Trace, gc, task, stats)) { 2950 return; 2951 } 2952 Log(gc, task, stats) log; 2953 ResourceMark rm; 2954 outputStream* st = log.trace_stream(); 2955 2956 print_taskqueue_stats_hdr(st); 2957 2958 TaskQueueStats totals; 2959 const uint n = num_task_queues(); 2960 for (uint i = 0; i < n; ++i) { 2961 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2962 totals += task_queue(i)->stats; 2963 } 2964 st->print_raw("tot "); totals.print(st); st->cr(); 2965 2966 DEBUG_ONLY(totals.verify()); 2967 } 2968 2969 void G1CollectedHeap::reset_taskqueue_stats() { 2970 const uint n = num_task_queues(); 2971 for (uint i = 0; i < n; ++i) { 2972 task_queue(i)->stats.reset(); 2973 } 2974 } 2975 #endif // TASKQUEUE_STATS 2976 2977 void G1CollectedHeap::wait_for_root_region_scanning() { 2978 double scan_wait_start = os::elapsedTime(); 2979 // We have to wait until the CM threads finish scanning the 2980 // root regions as it's the only way to ensure that all the 2981 // objects on them have been correctly scanned before we start 2982 // moving them during the GC. 2983 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2984 double wait_time_ms = 0.0; 2985 if (waited) { 2986 double scan_wait_end = os::elapsedTime(); 2987 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2988 } 2989 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2990 } 2991 2992 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2993 private: 2994 G1HRPrinter* _hr_printer; 2995 public: 2996 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2997 2998 virtual bool doHeapRegion(HeapRegion* r) { 2999 _hr_printer->cset(r); 3000 return false; 3001 } 3002 }; 3003 3004 bool 3005 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3006 assert_at_safepoint(true /* should_be_vm_thread */); 3007 guarantee(!is_gc_active(), "collection is not reentrant"); 3008 3009 if (GCLocker::check_active_before_gc()) { 3010 return false; 3011 } 3012 3013 _gc_timer_stw->register_gc_start(); 3014 3015 GCIdMark gc_id_mark; 3016 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3017 3018 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3019 ResourceMark rm; 3020 3021 g1_policy()->note_gc_start(); 3022 3023 wait_for_root_region_scanning(); 3024 3025 print_heap_before_gc(); 3026 print_heap_regions(); 3027 trace_heap_before_gc(_gc_tracer_stw); 3028 3029 _verifier->verify_region_sets_optional(); 3030 _verifier->verify_dirty_young_regions(); 3031 3032 // We should not be doing initial mark unless the conc mark thread is running 3033 if (!_cmThread->should_terminate()) { 3034 // This call will decide whether this pause is an initial-mark 3035 // pause. If it is, during_initial_mark_pause() will return true 3036 // for the duration of this pause. 3037 g1_policy()->decide_on_conc_mark_initiation(); 3038 } 3039 3040 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3041 assert(!collector_state()->during_initial_mark_pause() || 3042 collector_state()->gcs_are_young(), "sanity"); 3043 3044 // We also do not allow mixed GCs during marking. 3045 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity"); 3046 3047 // Record whether this pause is an initial mark. When the current 3048 // thread has completed its logging output and it's safe to signal 3049 // the CM thread, the flag's value in the policy has been reset. 3050 bool should_start_conc_mark = collector_state()->during_initial_mark_pause(); 3051 3052 // Inner scope for scope based logging, timers, and stats collection 3053 { 3054 EvacuationInfo evacuation_info; 3055 3056 if (collector_state()->during_initial_mark_pause()) { 3057 // We are about to start a marking cycle, so we increment the 3058 // full collection counter. 3059 increment_old_marking_cycles_started(); 3060 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 3061 } 3062 3063 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 3064 3065 GCTraceCPUTime tcpu; 3066 3067 FormatBuffer<> gc_string("Pause "); 3068 if (collector_state()->during_initial_mark_pause()) { 3069 gc_string.append("Initial Mark"); 3070 } else if (collector_state()->gcs_are_young()) { 3071 gc_string.append("Young"); 3072 } else { 3073 gc_string.append("Mixed"); 3074 } 3075 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true); 3076 3077 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 3078 workers()->active_workers(), 3079 Threads::number_of_non_daemon_threads()); 3080 workers()->update_active_workers(active_workers); 3081 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 3082 3083 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3084 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3085 3086 // If the secondary_free_list is not empty, append it to the 3087 // free_list. No need to wait for the cleanup operation to finish; 3088 // the region allocation code will check the secondary_free_list 3089 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3090 // set, skip this step so that the region allocation code has to 3091 // get entries from the secondary_free_list. 3092 if (!G1StressConcRegionFreeing) { 3093 append_secondary_free_list_if_not_empty_with_lock(); 3094 } 3095 3096 G1HeapTransition heap_transition(this); 3097 size_t heap_used_bytes_before_gc = used(); 3098 3099 // Don't dynamically change the number of GC threads this early. A value of 3100 // 0 is used to indicate serial work. When parallel work is done, 3101 // it will be set. 3102 3103 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3104 IsGCActiveMark x; 3105 3106 gc_prologue(false); 3107 increment_total_collections(false /* full gc */); 3108 increment_gc_time_stamp(); 3109 3110 if (VerifyRememberedSets) { 3111 log_info(gc, verify)("[Verifying RemSets before GC]"); 3112 VerifyRegionRemSetClosure v_cl; 3113 heap_region_iterate(&v_cl); 3114 } 3115 3116 _verifier->verify_before_gc(); 3117 3118 _verifier->check_bitmaps("GC Start"); 3119 3120 #if defined(COMPILER2) || INCLUDE_JVMCI 3121 DerivedPointerTable::clear(); 3122 #endif 3123 3124 // Please see comment in g1CollectedHeap.hpp and 3125 // G1CollectedHeap::ref_processing_init() to see how 3126 // reference processing currently works in G1. 3127 3128 // Enable discovery in the STW reference processor 3129 if (g1_policy()->should_process_references()) { 3130 ref_processor_stw()->enable_discovery(); 3131 } else { 3132 ref_processor_stw()->disable_discovery(); 3133 } 3134 3135 { 3136 // We want to temporarily turn off discovery by the 3137 // CM ref processor, if necessary, and turn it back on 3138 // on again later if we do. Using a scoped 3139 // NoRefDiscovery object will do this. 3140 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3141 3142 // Forget the current alloc region (we might even choose it to be part 3143 // of the collection set!). 3144 _allocator->release_mutator_alloc_region(); 3145 3146 // This timing is only used by the ergonomics to handle our pause target. 3147 // It is unclear why this should not include the full pause. We will 3148 // investigate this in CR 7178365. 3149 // 3150 // Preserving the old comment here if that helps the investigation: 3151 // 3152 // The elapsed time induced by the start time below deliberately elides 3153 // the possible verification above. 3154 double sample_start_time_sec = os::elapsedTime(); 3155 3156 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3157 3158 if (collector_state()->during_initial_mark_pause()) { 3159 concurrent_mark()->checkpointRootsInitialPre(); 3160 } 3161 3162 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor); 3163 3164 evacuation_info.set_collectionset_regions(collection_set()->region_length()); 3165 3166 // Make sure the remembered sets are up to date. This needs to be 3167 // done before register_humongous_regions_with_cset(), because the 3168 // remembered sets are used there to choose eager reclaim candidates. 3169 // If the remembered sets are not up to date we might miss some 3170 // entries that need to be handled. 3171 g1_rem_set()->cleanupHRRS(); 3172 3173 register_humongous_regions_with_cset(); 3174 3175 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3176 3177 // We call this after finalize_cset() to 3178 // ensure that the CSet has been finalized. 3179 _cm->verify_no_cset_oops(); 3180 3181 if (_hr_printer.is_active()) { 3182 G1PrintCollectionSetClosure cl(&_hr_printer); 3183 _collection_set.iterate(&cl); 3184 } 3185 3186 // Initialize the GC alloc regions. 3187 _allocator->init_gc_alloc_regions(evacuation_info); 3188 3189 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length()); 3190 pre_evacuate_collection_set(); 3191 3192 // Actually do the work... 3193 evacuate_collection_set(evacuation_info, &per_thread_states); 3194 3195 post_evacuate_collection_set(evacuation_info, &per_thread_states); 3196 3197 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 3198 free_collection_set(&_collection_set, evacuation_info, surviving_young_words); 3199 3200 eagerly_reclaim_humongous_regions(); 3201 3202 record_obj_copy_mem_stats(); 3203 _survivor_evac_stats.adjust_desired_plab_sz(); 3204 _old_evac_stats.adjust_desired_plab_sz(); 3205 3206 // Start a new incremental collection set for the next pause. 3207 collection_set()->start_incremental_building(); 3208 3209 clear_cset_fast_test(); 3210 3211 guarantee(_eden.length() == 0, "eden should have been cleared"); 3212 g1_policy()->transfer_survivors_to_cset(survivor()); 3213 3214 if (evacuation_failed()) { 3215 set_used(recalculate_used()); 3216 if (_archive_allocator != NULL) { 3217 _archive_allocator->clear_used(); 3218 } 3219 for (uint i = 0; i < ParallelGCThreads; i++) { 3220 if (_evacuation_failed_info_array[i].has_failed()) { 3221 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3222 } 3223 } 3224 } else { 3225 // The "used" of the the collection set have already been subtracted 3226 // when they were freed. Add in the bytes evacuated. 3227 increase_used(g1_policy()->bytes_copied_during_gc()); 3228 } 3229 3230 if (collector_state()->during_initial_mark_pause()) { 3231 // We have to do this before we notify the CM threads that 3232 // they can start working to make sure that all the 3233 // appropriate initialization is done on the CM object. 3234 concurrent_mark()->checkpointRootsInitialPost(); 3235 collector_state()->set_mark_in_progress(true); 3236 // Note that we don't actually trigger the CM thread at 3237 // this point. We do that later when we're sure that 3238 // the current thread has completed its logging output. 3239 } 3240 3241 allocate_dummy_regions(); 3242 3243 _allocator->init_mutator_alloc_region(); 3244 3245 { 3246 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 3247 if (expand_bytes > 0) { 3248 size_t bytes_before = capacity(); 3249 // No need for an ergo logging here, 3250 // expansion_amount() does this when it returns a value > 0. 3251 double expand_ms; 3252 if (!expand(expand_bytes, _workers, &expand_ms)) { 3253 // We failed to expand the heap. Cannot do anything about it. 3254 } 3255 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 3256 } 3257 } 3258 3259 // We redo the verification but now wrt to the new CSet which 3260 // has just got initialized after the previous CSet was freed. 3261 _cm->verify_no_cset_oops(); 3262 3263 // This timing is only used by the ergonomics to handle our pause target. 3264 // It is unclear why this should not include the full pause. We will 3265 // investigate this in CR 7178365. 3266 double sample_end_time_sec = os::elapsedTime(); 3267 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3268 size_t total_cards_scanned = per_thread_states.total_cards_scanned(); 3269 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc); 3270 3271 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3272 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 3273 3274 MemoryService::track_memory_usage(); 3275 3276 // In prepare_for_verify() below we'll need to scan the deferred 3277 // update buffers to bring the RSets up-to-date if 3278 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 3279 // the update buffers we'll probably need to scan cards on the 3280 // regions we just allocated to (i.e., the GC alloc 3281 // regions). However, during the last GC we called 3282 // set_saved_mark() on all the GC alloc regions, so card 3283 // scanning might skip the [saved_mark_word()...top()] area of 3284 // those regions (i.e., the area we allocated objects into 3285 // during the last GC). But it shouldn't. Given that 3286 // saved_mark_word() is conditional on whether the GC time stamp 3287 // on the region is current or not, by incrementing the GC time 3288 // stamp here we invalidate all the GC time stamps on all the 3289 // regions and saved_mark_word() will simply return top() for 3290 // all the regions. This is a nicer way of ensuring this rather 3291 // than iterating over the regions and fixing them. In fact, the 3292 // GC time stamp increment here also ensures that 3293 // saved_mark_word() will return top() between pauses, i.e., 3294 // during concurrent refinement. So we don't need the 3295 // is_gc_active() check to decided which top to use when 3296 // scanning cards (see CR 7039627). 3297 increment_gc_time_stamp(); 3298 3299 if (VerifyRememberedSets) { 3300 log_info(gc, verify)("[Verifying RemSets after GC]"); 3301 VerifyRegionRemSetClosure v_cl; 3302 heap_region_iterate(&v_cl); 3303 } 3304 3305 _verifier->verify_after_gc(); 3306 _verifier->check_bitmaps("GC End"); 3307 3308 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 3309 ref_processor_stw()->verify_no_references_recorded(); 3310 3311 // CM reference discovery will be re-enabled if necessary. 3312 } 3313 3314 #ifdef TRACESPINNING 3315 ParallelTaskTerminator::print_termination_counts(); 3316 #endif 3317 3318 gc_epilogue(false); 3319 } 3320 3321 // Print the remainder of the GC log output. 3322 if (evacuation_failed()) { 3323 log_info(gc)("To-space exhausted"); 3324 } 3325 3326 g1_policy()->print_phases(); 3327 heap_transition.print(); 3328 3329 // It is not yet to safe to tell the concurrent mark to 3330 // start as we have some optional output below. We don't want the 3331 // output from the concurrent mark thread interfering with this 3332 // logging output either. 3333 3334 _hrm.verify_optional(); 3335 _verifier->verify_region_sets_optional(); 3336 3337 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3338 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3339 3340 print_heap_after_gc(); 3341 print_heap_regions(); 3342 trace_heap_after_gc(_gc_tracer_stw); 3343 3344 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3345 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3346 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3347 // before any GC notifications are raised. 3348 g1mm()->update_sizes(); 3349 3350 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3351 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 3352 _gc_timer_stw->register_gc_end(); 3353 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3354 } 3355 // It should now be safe to tell the concurrent mark thread to start 3356 // without its logging output interfering with the logging output 3357 // that came from the pause. 3358 3359 if (should_start_conc_mark) { 3360 // CAUTION: after the doConcurrentMark() call below, 3361 // the concurrent marking thread(s) could be running 3362 // concurrently with us. Make sure that anything after 3363 // this point does not assume that we are the only GC thread 3364 // running. Note: of course, the actual marking work will 3365 // not start until the safepoint itself is released in 3366 // SuspendibleThreadSet::desynchronize(). 3367 doConcurrentMark(); 3368 } 3369 3370 return true; 3371 } 3372 3373 void G1CollectedHeap::remove_self_forwarding_pointers() { 3374 G1ParRemoveSelfForwardPtrsTask rsfp_task; 3375 workers()->run_task(&rsfp_task); 3376 } 3377 3378 void G1CollectedHeap::restore_after_evac_failure() { 3379 double remove_self_forwards_start = os::elapsedTime(); 3380 3381 remove_self_forwarding_pointers(); 3382 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3383 _preserved_marks_set.restore(&task_executor); 3384 3385 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3386 } 3387 3388 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 3389 if (!_evacuation_failed) { 3390 _evacuation_failed = true; 3391 } 3392 3393 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3394 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3395 } 3396 3397 bool G1ParEvacuateFollowersClosure::offer_termination() { 3398 G1ParScanThreadState* const pss = par_scan_state(); 3399 start_term_time(); 3400 const bool res = terminator()->offer_termination(); 3401 end_term_time(); 3402 return res; 3403 } 3404 3405 void G1ParEvacuateFollowersClosure::do_void() { 3406 G1ParScanThreadState* const pss = par_scan_state(); 3407 pss->trim_queue(); 3408 do { 3409 pss->steal_and_trim_queue(queues()); 3410 } while (!offer_termination()); 3411 } 3412 3413 class G1ParTask : public AbstractGangTask { 3414 protected: 3415 G1CollectedHeap* _g1h; 3416 G1ParScanThreadStateSet* _pss; 3417 RefToScanQueueSet* _queues; 3418 G1RootProcessor* _root_processor; 3419 ParallelTaskTerminator _terminator; 3420 uint _n_workers; 3421 3422 public: 3423 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 3424 : AbstractGangTask("G1 collection"), 3425 _g1h(g1h), 3426 _pss(per_thread_states), 3427 _queues(task_queues), 3428 _root_processor(root_processor), 3429 _terminator(n_workers, _queues), 3430 _n_workers(n_workers) 3431 {} 3432 3433 void work(uint worker_id) { 3434 if (worker_id >= _n_workers) return; // no work needed this round 3435 3436 double start_sec = os::elapsedTime(); 3437 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 3438 3439 { 3440 ResourceMark rm; 3441 HandleMark hm; 3442 3443 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 3444 3445 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3446 pss->set_ref_processor(rp); 3447 3448 double start_strong_roots_sec = os::elapsedTime(); 3449 3450 _root_processor->evacuate_roots(pss->closures(), worker_id); 3451 3452 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss); 3453 3454 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid 3455 // treating the nmethods visited to act as roots for concurrent marking. 3456 // We only want to make sure that the oops in the nmethods are adjusted with regard to the 3457 // objects copied by the current evacuation. 3458 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl, 3459 pss->closures()->weak_codeblobs(), 3460 worker_id); 3461 3462 _pss->add_cards_scanned(worker_id, cards_scanned); 3463 3464 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 3465 3466 double term_sec = 0.0; 3467 size_t evac_term_attempts = 0; 3468 { 3469 double start = os::elapsedTime(); 3470 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator); 3471 evac.do_void(); 3472 3473 evac_term_attempts = evac.term_attempts(); 3474 term_sec = evac.term_time(); 3475 double elapsed_sec = os::elapsedTime() - start; 3476 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 3477 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 3478 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 3479 } 3480 3481 assert(pss->queue_is_empty(), "should be empty"); 3482 3483 if (log_is_enabled(Debug, gc, task, stats)) { 3484 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3485 size_t lab_waste; 3486 size_t lab_undo_waste; 3487 pss->waste(lab_waste, lab_undo_waste); 3488 _g1h->print_termination_stats(worker_id, 3489 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 3490 strong_roots_sec * 1000.0, /* strong roots time */ 3491 term_sec * 1000.0, /* evac term time */ 3492 evac_term_attempts, /* evac term attempts */ 3493 lab_waste, /* alloc buffer waste */ 3494 lab_undo_waste /* undo waste */ 3495 ); 3496 } 3497 3498 // Close the inner scope so that the ResourceMark and HandleMark 3499 // destructors are executed here and are included as part of the 3500 // "GC Worker Time". 3501 } 3502 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 3503 } 3504 }; 3505 3506 void G1CollectedHeap::print_termination_stats_hdr() { 3507 log_debug(gc, task, stats)("GC Termination Stats"); 3508 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 3509 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo"); 3510 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 3511 } 3512 3513 void G1CollectedHeap::print_termination_stats(uint worker_id, 3514 double elapsed_ms, 3515 double strong_roots_ms, 3516 double term_ms, 3517 size_t term_attempts, 3518 size_t alloc_buffer_waste, 3519 size_t undo_waste) const { 3520 log_debug(gc, task, stats) 3521 ("%3d %9.2f %9.2f %6.2f " 3522 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 3523 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 3524 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 3525 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 3526 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 3527 alloc_buffer_waste * HeapWordSize / K, 3528 undo_waste * HeapWordSize / K); 3529 } 3530 3531 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 3532 private: 3533 BoolObjectClosure* _is_alive; 3534 int _initial_string_table_size; 3535 int _initial_symbol_table_size; 3536 3537 bool _process_strings; 3538 int _strings_processed; 3539 int _strings_removed; 3540 3541 bool _process_symbols; 3542 int _symbols_processed; 3543 int _symbols_removed; 3544 3545 public: 3546 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 3547 AbstractGangTask("String/Symbol Unlinking"), 3548 _is_alive(is_alive), 3549 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 3550 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 3551 3552 _initial_string_table_size = StringTable::the_table()->table_size(); 3553 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 3554 if (process_strings) { 3555 StringTable::clear_parallel_claimed_index(); 3556 } 3557 if (process_symbols) { 3558 SymbolTable::clear_parallel_claimed_index(); 3559 } 3560 } 3561 3562 ~G1StringSymbolTableUnlinkTask() { 3563 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 3564 "claim value %d after unlink less than initial string table size %d", 3565 StringTable::parallel_claimed_index(), _initial_string_table_size); 3566 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 3567 "claim value %d after unlink less than initial symbol table size %d", 3568 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size); 3569 3570 log_info(gc, stringtable)( 3571 "Cleaned string and symbol table, " 3572 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, " 3573 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed", 3574 strings_processed(), strings_removed(), 3575 symbols_processed(), symbols_removed()); 3576 } 3577 3578 void work(uint worker_id) { 3579 int strings_processed = 0; 3580 int strings_removed = 0; 3581 int symbols_processed = 0; 3582 int symbols_removed = 0; 3583 if (_process_strings) { 3584 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 3585 Atomic::add(strings_processed, &_strings_processed); 3586 Atomic::add(strings_removed, &_strings_removed); 3587 } 3588 if (_process_symbols) { 3589 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 3590 Atomic::add(symbols_processed, &_symbols_processed); 3591 Atomic::add(symbols_removed, &_symbols_removed); 3592 } 3593 } 3594 3595 size_t strings_processed() const { return (size_t)_strings_processed; } 3596 size_t strings_removed() const { return (size_t)_strings_removed; } 3597 3598 size_t symbols_processed() const { return (size_t)_symbols_processed; } 3599 size_t symbols_removed() const { return (size_t)_symbols_removed; } 3600 }; 3601 3602 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 3603 private: 3604 static Monitor* _lock; 3605 3606 BoolObjectClosure* const _is_alive; 3607 const bool _unloading_occurred; 3608 const uint _num_workers; 3609 3610 // Variables used to claim nmethods. 3611 CompiledMethod* _first_nmethod; 3612 volatile CompiledMethod* _claimed_nmethod; 3613 3614 // The list of nmethods that need to be processed by the second pass. 3615 volatile CompiledMethod* _postponed_list; 3616 volatile uint _num_entered_barrier; 3617 3618 public: 3619 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 3620 _is_alive(is_alive), 3621 _unloading_occurred(unloading_occurred), 3622 _num_workers(num_workers), 3623 _first_nmethod(NULL), 3624 _claimed_nmethod(NULL), 3625 _postponed_list(NULL), 3626 _num_entered_barrier(0) 3627 { 3628 CompiledMethod::increase_unloading_clock(); 3629 // Get first alive nmethod 3630 CompiledMethodIterator iter = CompiledMethodIterator(); 3631 if(iter.next_alive()) { 3632 _first_nmethod = iter.method(); 3633 } 3634 _claimed_nmethod = (volatile CompiledMethod*)_first_nmethod; 3635 } 3636 3637 ~G1CodeCacheUnloadingTask() { 3638 CodeCache::verify_clean_inline_caches(); 3639 3640 CodeCache::set_needs_cache_clean(false); 3641 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 3642 3643 CodeCache::verify_icholder_relocations(); 3644 } 3645 3646 private: 3647 void add_to_postponed_list(CompiledMethod* nm) { 3648 CompiledMethod* old; 3649 do { 3650 old = (CompiledMethod*)_postponed_list; 3651 nm->set_unloading_next(old); 3652 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 3653 } 3654 3655 void clean_nmethod(CompiledMethod* nm) { 3656 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 3657 3658 if (postponed) { 3659 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 3660 add_to_postponed_list(nm); 3661 } 3662 3663 // Mark that this thread has been cleaned/unloaded. 3664 // After this call, it will be safe to ask if this nmethod was unloaded or not. 3665 nm->set_unloading_clock(CompiledMethod::global_unloading_clock()); 3666 } 3667 3668 void clean_nmethod_postponed(CompiledMethod* nm) { 3669 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 3670 } 3671 3672 static const int MaxClaimNmethods = 16; 3673 3674 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) { 3675 CompiledMethod* first; 3676 CompiledMethodIterator last; 3677 3678 do { 3679 *num_claimed_nmethods = 0; 3680 3681 first = (CompiledMethod*)_claimed_nmethod; 3682 last = CompiledMethodIterator(first); 3683 3684 if (first != NULL) { 3685 3686 for (int i = 0; i < MaxClaimNmethods; i++) { 3687 if (!last.next_alive()) { 3688 break; 3689 } 3690 claimed_nmethods[i] = last.method(); 3691 (*num_claimed_nmethods)++; 3692 } 3693 } 3694 3695 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 3696 } 3697 3698 CompiledMethod* claim_postponed_nmethod() { 3699 CompiledMethod* claim; 3700 CompiledMethod* next; 3701 3702 do { 3703 claim = (CompiledMethod*)_postponed_list; 3704 if (claim == NULL) { 3705 return NULL; 3706 } 3707 3708 next = claim->unloading_next(); 3709 3710 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 3711 3712 return claim; 3713 } 3714 3715 public: 3716 // Mark that we're done with the first pass of nmethod cleaning. 3717 void barrier_mark(uint worker_id) { 3718 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3719 _num_entered_barrier++; 3720 if (_num_entered_barrier == _num_workers) { 3721 ml.notify_all(); 3722 } 3723 } 3724 3725 // See if we have to wait for the other workers to 3726 // finish their first-pass nmethod cleaning work. 3727 void barrier_wait(uint worker_id) { 3728 if (_num_entered_barrier < _num_workers) { 3729 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3730 while (_num_entered_barrier < _num_workers) { 3731 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 3732 } 3733 } 3734 } 3735 3736 // Cleaning and unloading of nmethods. Some work has to be postponed 3737 // to the second pass, when we know which nmethods survive. 3738 void work_first_pass(uint worker_id) { 3739 // The first nmethods is claimed by the first worker. 3740 if (worker_id == 0 && _first_nmethod != NULL) { 3741 clean_nmethod(_first_nmethod); 3742 _first_nmethod = NULL; 3743 } 3744 3745 int num_claimed_nmethods; 3746 CompiledMethod* claimed_nmethods[MaxClaimNmethods]; 3747 3748 while (true) { 3749 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 3750 3751 if (num_claimed_nmethods == 0) { 3752 break; 3753 } 3754 3755 for (int i = 0; i < num_claimed_nmethods; i++) { 3756 clean_nmethod(claimed_nmethods[i]); 3757 } 3758 } 3759 } 3760 3761 void work_second_pass(uint worker_id) { 3762 CompiledMethod* nm; 3763 // Take care of postponed nmethods. 3764 while ((nm = claim_postponed_nmethod()) != NULL) { 3765 clean_nmethod_postponed(nm); 3766 } 3767 } 3768 }; 3769 3770 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 3771 3772 class G1KlassCleaningTask : public StackObj { 3773 BoolObjectClosure* _is_alive; 3774 volatile jint _clean_klass_tree_claimed; 3775 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 3776 3777 public: 3778 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 3779 _is_alive(is_alive), 3780 _clean_klass_tree_claimed(0), 3781 _klass_iterator() { 3782 } 3783 3784 private: 3785 bool claim_clean_klass_tree_task() { 3786 if (_clean_klass_tree_claimed) { 3787 return false; 3788 } 3789 3790 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 3791 } 3792 3793 InstanceKlass* claim_next_klass() { 3794 Klass* klass; 3795 do { 3796 klass =_klass_iterator.next_klass(); 3797 } while (klass != NULL && !klass->is_instance_klass()); 3798 3799 // this can be null so don't call InstanceKlass::cast 3800 return static_cast<InstanceKlass*>(klass); 3801 } 3802 3803 public: 3804 3805 void clean_klass(InstanceKlass* ik) { 3806 ik->clean_weak_instanceklass_links(_is_alive); 3807 } 3808 3809 void work() { 3810 ResourceMark rm; 3811 3812 // One worker will clean the subklass/sibling klass tree. 3813 if (claim_clean_klass_tree_task()) { 3814 Klass::clean_subklass_tree(_is_alive); 3815 } 3816 3817 // All workers will help cleaning the classes, 3818 InstanceKlass* klass; 3819 while ((klass = claim_next_klass()) != NULL) { 3820 clean_klass(klass); 3821 } 3822 } 3823 }; 3824 3825 // To minimize the remark pause times, the tasks below are done in parallel. 3826 class G1ParallelCleaningTask : public AbstractGangTask { 3827 private: 3828 G1StringSymbolTableUnlinkTask _string_symbol_task; 3829 G1CodeCacheUnloadingTask _code_cache_task; 3830 G1KlassCleaningTask _klass_cleaning_task; 3831 3832 public: 3833 // The constructor is run in the VMThread. 3834 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 3835 AbstractGangTask("Parallel Cleaning"), 3836 _string_symbol_task(is_alive, process_strings, process_symbols), 3837 _code_cache_task(num_workers, is_alive, unloading_occurred), 3838 _klass_cleaning_task(is_alive) { 3839 } 3840 3841 // The parallel work done by all worker threads. 3842 void work(uint worker_id) { 3843 // Do first pass of code cache cleaning. 3844 _code_cache_task.work_first_pass(worker_id); 3845 3846 // Let the threads mark that the first pass is done. 3847 _code_cache_task.barrier_mark(worker_id); 3848 3849 // Clean the Strings and Symbols. 3850 _string_symbol_task.work(worker_id); 3851 3852 // Wait for all workers to finish the first code cache cleaning pass. 3853 _code_cache_task.barrier_wait(worker_id); 3854 3855 // Do the second code cache cleaning work, which realize on 3856 // the liveness information gathered during the first pass. 3857 _code_cache_task.work_second_pass(worker_id); 3858 3859 // Clean all klasses that were not unloaded. 3860 _klass_cleaning_task.work(); 3861 } 3862 }; 3863 3864 3865 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 3866 bool process_strings, 3867 bool process_symbols, 3868 bool class_unloading_occurred) { 3869 uint n_workers = workers()->active_workers(); 3870 3871 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 3872 n_workers, class_unloading_occurred); 3873 workers()->run_task(&g1_unlink_task); 3874 } 3875 3876 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 3877 bool process_strings, bool process_symbols) { 3878 { // Timing scope 3879 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 3880 workers()->run_task(&g1_unlink_task); 3881 } 3882 } 3883 3884 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3885 private: 3886 DirtyCardQueueSet* _queue; 3887 G1CollectedHeap* _g1h; 3888 public: 3889 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 3890 _queue(queue), _g1h(g1h) { } 3891 3892 virtual void work(uint worker_id) { 3893 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 3894 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 3895 3896 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3897 _queue->par_apply_closure_to_all_completed_buffers(&cl); 3898 3899 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3900 } 3901 }; 3902 3903 void G1CollectedHeap::redirty_logged_cards() { 3904 double redirty_logged_cards_start = os::elapsedTime(); 3905 3906 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 3907 dirty_card_queue_set().reset_for_par_iteration(); 3908 workers()->run_task(&redirty_task); 3909 3910 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 3911 dcq.merge_bufferlists(&dirty_card_queue_set()); 3912 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 3913 3914 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3915 } 3916 3917 // Weak Reference Processing support 3918 3919 // An always "is_alive" closure that is used to preserve referents. 3920 // If the object is non-null then it's alive. Used in the preservation 3921 // of referent objects that are pointed to by reference objects 3922 // discovered by the CM ref processor. 3923 class G1AlwaysAliveClosure: public BoolObjectClosure { 3924 G1CollectedHeap* _g1; 3925 public: 3926 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 3927 bool do_object_b(oop p) { 3928 if (p != NULL) { 3929 return true; 3930 } 3931 return false; 3932 } 3933 }; 3934 3935 bool G1STWIsAliveClosure::do_object_b(oop p) { 3936 // An object is reachable if it is outside the collection set, 3937 // or is inside and copied. 3938 return !_g1->is_in_cset(p) || p->is_forwarded(); 3939 } 3940 3941 // Non Copying Keep Alive closure 3942 class G1KeepAliveClosure: public OopClosure { 3943 G1CollectedHeap* _g1; 3944 public: 3945 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 3946 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3947 void do_oop(oop* p) { 3948 oop obj = *p; 3949 assert(obj != NULL, "the caller should have filtered out NULL values"); 3950 3951 const InCSetState cset_state = _g1->in_cset_state(obj); 3952 if (!cset_state.is_in_cset_or_humongous()) { 3953 return; 3954 } 3955 if (cset_state.is_in_cset()) { 3956 assert( obj->is_forwarded(), "invariant" ); 3957 *p = obj->forwardee(); 3958 } else { 3959 assert(!obj->is_forwarded(), "invariant" ); 3960 assert(cset_state.is_humongous(), 3961 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 3962 _g1->set_humongous_is_live(obj); 3963 } 3964 } 3965 }; 3966 3967 // Copying Keep Alive closure - can be called from both 3968 // serial and parallel code as long as different worker 3969 // threads utilize different G1ParScanThreadState instances 3970 // and different queues. 3971 3972 class G1CopyingKeepAliveClosure: public OopClosure { 3973 G1CollectedHeap* _g1h; 3974 OopClosure* _copy_non_heap_obj_cl; 3975 G1ParScanThreadState* _par_scan_state; 3976 3977 public: 3978 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3979 OopClosure* non_heap_obj_cl, 3980 G1ParScanThreadState* pss): 3981 _g1h(g1h), 3982 _copy_non_heap_obj_cl(non_heap_obj_cl), 3983 _par_scan_state(pss) 3984 {} 3985 3986 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3987 virtual void do_oop( oop* p) { do_oop_work(p); } 3988 3989 template <class T> void do_oop_work(T* p) { 3990 oop obj = oopDesc::load_decode_heap_oop(p); 3991 3992 if (_g1h->is_in_cset_or_humongous(obj)) { 3993 // If the referent object has been forwarded (either copied 3994 // to a new location or to itself in the event of an 3995 // evacuation failure) then we need to update the reference 3996 // field and, if both reference and referent are in the G1 3997 // heap, update the RSet for the referent. 3998 // 3999 // If the referent has not been forwarded then we have to keep 4000 // it alive by policy. Therefore we have copy the referent. 4001 // 4002 // If the reference field is in the G1 heap then we can push 4003 // on the PSS queue. When the queue is drained (after each 4004 // phase of reference processing) the object and it's followers 4005 // will be copied, the reference field set to point to the 4006 // new location, and the RSet updated. Otherwise we need to 4007 // use the the non-heap or metadata closures directly to copy 4008 // the referent object and update the pointer, while avoiding 4009 // updating the RSet. 4010 4011 if (_g1h->is_in_g1_reserved(p)) { 4012 _par_scan_state->push_on_queue(p); 4013 } else { 4014 assert(!Metaspace::contains((const void*)p), 4015 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)); 4016 _copy_non_heap_obj_cl->do_oop(p); 4017 } 4018 } 4019 } 4020 }; 4021 4022 // Serial drain queue closure. Called as the 'complete_gc' 4023 // closure for each discovered list in some of the 4024 // reference processing phases. 4025 4026 class G1STWDrainQueueClosure: public VoidClosure { 4027 protected: 4028 G1CollectedHeap* _g1h; 4029 G1ParScanThreadState* _par_scan_state; 4030 4031 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4032 4033 public: 4034 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 4035 _g1h(g1h), 4036 _par_scan_state(pss) 4037 { } 4038 4039 void do_void() { 4040 G1ParScanThreadState* const pss = par_scan_state(); 4041 pss->trim_queue(); 4042 } 4043 }; 4044 4045 // Parallel Reference Processing closures 4046 4047 // Implementation of AbstractRefProcTaskExecutor for parallel reference 4048 // processing during G1 evacuation pauses. 4049 4050 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 4051 private: 4052 G1CollectedHeap* _g1h; 4053 G1ParScanThreadStateSet* _pss; 4054 RefToScanQueueSet* _queues; 4055 WorkGang* _workers; 4056 uint _active_workers; 4057 4058 public: 4059 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 4060 G1ParScanThreadStateSet* per_thread_states, 4061 WorkGang* workers, 4062 RefToScanQueueSet *task_queues, 4063 uint n_workers) : 4064 _g1h(g1h), 4065 _pss(per_thread_states), 4066 _queues(task_queues), 4067 _workers(workers), 4068 _active_workers(n_workers) 4069 { 4070 g1h->ref_processor_stw()->set_active_mt_degree(n_workers); 4071 } 4072 4073 // Executes the given task using concurrent marking worker threads. 4074 virtual void execute(ProcessTask& task); 4075 virtual void execute(EnqueueTask& task); 4076 }; 4077 4078 // Gang task for possibly parallel reference processing 4079 4080 class G1STWRefProcTaskProxy: public AbstractGangTask { 4081 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 4082 ProcessTask& _proc_task; 4083 G1CollectedHeap* _g1h; 4084 G1ParScanThreadStateSet* _pss; 4085 RefToScanQueueSet* _task_queues; 4086 ParallelTaskTerminator* _terminator; 4087 4088 public: 4089 G1STWRefProcTaskProxy(ProcessTask& proc_task, 4090 G1CollectedHeap* g1h, 4091 G1ParScanThreadStateSet* per_thread_states, 4092 RefToScanQueueSet *task_queues, 4093 ParallelTaskTerminator* terminator) : 4094 AbstractGangTask("Process reference objects in parallel"), 4095 _proc_task(proc_task), 4096 _g1h(g1h), 4097 _pss(per_thread_states), 4098 _task_queues(task_queues), 4099 _terminator(terminator) 4100 {} 4101 4102 virtual void work(uint worker_id) { 4103 // The reference processing task executed by a single worker. 4104 ResourceMark rm; 4105 HandleMark hm; 4106 4107 G1STWIsAliveClosure is_alive(_g1h); 4108 4109 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4110 pss->set_ref_processor(NULL); 4111 4112 // Keep alive closure. 4113 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 4114 4115 // Complete GC closure 4116 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator); 4117 4118 // Call the reference processing task's work routine. 4119 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 4120 4121 // Note we cannot assert that the refs array is empty here as not all 4122 // of the processing tasks (specifically phase2 - pp2_work) execute 4123 // the complete_gc closure (which ordinarily would drain the queue) so 4124 // the queue may not be empty. 4125 } 4126 }; 4127 4128 // Driver routine for parallel reference processing. 4129 // Creates an instance of the ref processing gang 4130 // task and has the worker threads execute it. 4131 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 4132 assert(_workers != NULL, "Need parallel worker threads."); 4133 4134 ParallelTaskTerminator terminator(_active_workers, _queues); 4135 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 4136 4137 _workers->run_task(&proc_task_proxy); 4138 } 4139 4140 // Gang task for parallel reference enqueueing. 4141 4142 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 4143 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 4144 EnqueueTask& _enq_task; 4145 4146 public: 4147 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 4148 AbstractGangTask("Enqueue reference objects in parallel"), 4149 _enq_task(enq_task) 4150 { } 4151 4152 virtual void work(uint worker_id) { 4153 _enq_task.work(worker_id); 4154 } 4155 }; 4156 4157 // Driver routine for parallel reference enqueueing. 4158 // Creates an instance of the ref enqueueing gang 4159 // task and has the worker threads execute it. 4160 4161 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 4162 assert(_workers != NULL, "Need parallel worker threads."); 4163 4164 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 4165 4166 _workers->run_task(&enq_task_proxy); 4167 } 4168 4169 // End of weak reference support closures 4170 4171 // Abstract task used to preserve (i.e. copy) any referent objects 4172 // that are in the collection set and are pointed to by reference 4173 // objects discovered by the CM ref processor. 4174 4175 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 4176 protected: 4177 G1CollectedHeap* _g1h; 4178 G1ParScanThreadStateSet* _pss; 4179 RefToScanQueueSet* _queues; 4180 ParallelTaskTerminator _terminator; 4181 uint _n_workers; 4182 4183 public: 4184 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) : 4185 AbstractGangTask("ParPreserveCMReferents"), 4186 _g1h(g1h), 4187 _pss(per_thread_states), 4188 _queues(task_queues), 4189 _terminator(workers, _queues), 4190 _n_workers(workers) 4191 { 4192 g1h->ref_processor_cm()->set_active_mt_degree(workers); 4193 } 4194 4195 void work(uint worker_id) { 4196 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id); 4197 4198 ResourceMark rm; 4199 HandleMark hm; 4200 4201 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4202 pss->set_ref_processor(NULL); 4203 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 4204 4205 // Is alive closure 4206 G1AlwaysAliveClosure always_alive(_g1h); 4207 4208 // Copying keep alive closure. Applied to referent objects that need 4209 // to be copied. 4210 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 4211 4212 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 4213 4214 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 4215 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 4216 4217 // limit is set using max_num_q() - which was set using ParallelGCThreads. 4218 // So this must be true - but assert just in case someone decides to 4219 // change the worker ids. 4220 assert(worker_id < limit, "sanity"); 4221 assert(!rp->discovery_is_atomic(), "check this code"); 4222 4223 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 4224 for (uint idx = worker_id; idx < limit; idx += stride) { 4225 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 4226 4227 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 4228 while (iter.has_next()) { 4229 // Since discovery is not atomic for the CM ref processor, we 4230 // can see some null referent objects. 4231 iter.load_ptrs(DEBUG_ONLY(true)); 4232 oop ref = iter.obj(); 4233 4234 // This will filter nulls. 4235 if (iter.is_referent_alive()) { 4236 iter.make_referent_alive(); 4237 } 4238 iter.move_to_next(); 4239 } 4240 } 4241 4242 // Drain the queue - which may cause stealing 4243 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator); 4244 drain_queue.do_void(); 4245 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 4246 assert(pss->queue_is_empty(), "should be"); 4247 } 4248 }; 4249 4250 void G1CollectedHeap::process_weak_jni_handles() { 4251 double ref_proc_start = os::elapsedTime(); 4252 4253 G1STWIsAliveClosure is_alive(this); 4254 G1KeepAliveClosure keep_alive(this); 4255 JNIHandles::weak_oops_do(&is_alive, &keep_alive); 4256 4257 double ref_proc_time = os::elapsedTime() - ref_proc_start; 4258 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 4259 } 4260 4261 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) { 4262 // Any reference objects, in the collection set, that were 'discovered' 4263 // by the CM ref processor should have already been copied (either by 4264 // applying the external root copy closure to the discovered lists, or 4265 // by following an RSet entry). 4266 // 4267 // But some of the referents, that are in the collection set, that these 4268 // reference objects point to may not have been copied: the STW ref 4269 // processor would have seen that the reference object had already 4270 // been 'discovered' and would have skipped discovering the reference, 4271 // but would not have treated the reference object as a regular oop. 4272 // As a result the copy closure would not have been applied to the 4273 // referent object. 4274 // 4275 // We need to explicitly copy these referent objects - the references 4276 // will be processed at the end of remarking. 4277 // 4278 // We also need to do this copying before we process the reference 4279 // objects discovered by the STW ref processor in case one of these 4280 // referents points to another object which is also referenced by an 4281 // object discovered by the STW ref processor. 4282 double preserve_cm_referents_time = 0.0; 4283 4284 // To avoid spawning task when there is no work to do, check that 4285 // a concurrent cycle is active and that some references have been 4286 // discovered. 4287 if (concurrent_mark()->cmThread()->during_cycle() && 4288 ref_processor_cm()->has_discovered_references()) { 4289 double preserve_cm_referents_start = os::elapsedTime(); 4290 uint no_of_gc_workers = workers()->active_workers(); 4291 G1ParPreserveCMReferentsTask keep_cm_referents(this, 4292 per_thread_states, 4293 no_of_gc_workers, 4294 _task_queues); 4295 workers()->run_task(&keep_cm_referents); 4296 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start; 4297 } 4298 4299 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0); 4300 } 4301 4302 // Weak Reference processing during an evacuation pause (part 1). 4303 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 4304 double ref_proc_start = os::elapsedTime(); 4305 4306 ReferenceProcessor* rp = _ref_processor_stw; 4307 assert(rp->discovery_enabled(), "should have been enabled"); 4308 4309 // Closure to test whether a referent is alive. 4310 G1STWIsAliveClosure is_alive(this); 4311 4312 // Even when parallel reference processing is enabled, the processing 4313 // of JNI refs is serial and performed serially by the current thread 4314 // rather than by a worker. The following PSS will be used for processing 4315 // JNI refs. 4316 4317 // Use only a single queue for this PSS. 4318 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 4319 pss->set_ref_processor(NULL); 4320 assert(pss->queue_is_empty(), "pre-condition"); 4321 4322 // Keep alive closure. 4323 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss); 4324 4325 // Serial Complete GC closure 4326 G1STWDrainQueueClosure drain_queue(this, pss); 4327 4328 // Setup the soft refs policy... 4329 rp->setup_policy(false); 4330 4331 ReferenceProcessorStats stats; 4332 if (!rp->processing_is_mt()) { 4333 // Serial reference processing... 4334 stats = rp->process_discovered_references(&is_alive, 4335 &keep_alive, 4336 &drain_queue, 4337 NULL, 4338 _gc_timer_stw); 4339 } else { 4340 uint no_of_gc_workers = workers()->active_workers(); 4341 4342 // Parallel reference processing 4343 assert(no_of_gc_workers <= rp->max_num_q(), 4344 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 4345 no_of_gc_workers, rp->max_num_q()); 4346 4347 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers); 4348 stats = rp->process_discovered_references(&is_alive, 4349 &keep_alive, 4350 &drain_queue, 4351 &par_task_executor, 4352 _gc_timer_stw); 4353 } 4354 4355 _gc_tracer_stw->report_gc_reference_stats(stats); 4356 4357 // We have completed copying any necessary live referent objects. 4358 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 4359 4360 double ref_proc_time = os::elapsedTime() - ref_proc_start; 4361 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 4362 } 4363 4364 // Weak Reference processing during an evacuation pause (part 2). 4365 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 4366 double ref_enq_start = os::elapsedTime(); 4367 4368 ReferenceProcessor* rp = _ref_processor_stw; 4369 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 4370 4371 // Now enqueue any remaining on the discovered lists on to 4372 // the pending list. 4373 if (!rp->processing_is_mt()) { 4374 // Serial reference processing... 4375 rp->enqueue_discovered_references(); 4376 } else { 4377 // Parallel reference enqueueing 4378 4379 uint n_workers = workers()->active_workers(); 4380 4381 assert(n_workers <= rp->max_num_q(), 4382 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 4383 n_workers, rp->max_num_q()); 4384 4385 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers); 4386 rp->enqueue_discovered_references(&par_task_executor); 4387 } 4388 4389 rp->verify_no_references_recorded(); 4390 assert(!rp->discovery_enabled(), "should have been disabled"); 4391 4392 // FIXME 4393 // CM's reference processing also cleans up the string and symbol tables. 4394 // Should we do that here also? We could, but it is a serial operation 4395 // and could significantly increase the pause time. 4396 4397 double ref_enq_time = os::elapsedTime() - ref_enq_start; 4398 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 4399 } 4400 4401 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 4402 double merge_pss_time_start = os::elapsedTime(); 4403 per_thread_states->flush(); 4404 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 4405 } 4406 4407 void G1CollectedHeap::pre_evacuate_collection_set() { 4408 _expand_heap_after_alloc_failure = true; 4409 _evacuation_failed = false; 4410 4411 // Disable the hot card cache. 4412 _hot_card_cache->reset_hot_cache_claimed_index(); 4413 _hot_card_cache->set_use_cache(false); 4414 4415 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 4416 _preserved_marks_set.assert_empty(); 4417 } 4418 4419 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 4420 // Should G1EvacuationFailureALot be in effect for this GC? 4421 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 4422 4423 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 4424 4425 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 4426 4427 // InitialMark needs claim bits to keep track of the marked-through CLDs. 4428 if (collector_state()->during_initial_mark_pause()) { 4429 double start_clear_claimed_marks = os::elapsedTime(); 4430 4431 ClassLoaderDataGraph::clear_claimed_marks(); 4432 4433 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 4434 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 4435 } 4436 4437 double start_par_time_sec = os::elapsedTime(); 4438 double end_par_time_sec; 4439 4440 { 4441 const uint n_workers = workers()->active_workers(); 4442 G1RootProcessor root_processor(this, n_workers); 4443 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 4444 4445 print_termination_stats_hdr(); 4446 4447 workers()->run_task(&g1_par_task); 4448 end_par_time_sec = os::elapsedTime(); 4449 4450 // Closing the inner scope will execute the destructor 4451 // for the G1RootProcessor object. We record the current 4452 // elapsed time before closing the scope so that time 4453 // taken for the destructor is NOT included in the 4454 // reported parallel time. 4455 } 4456 4457 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 4458 phase_times->record_par_time(par_time_ms); 4459 4460 double code_root_fixup_time_ms = 4461 (os::elapsedTime() - end_par_time_sec) * 1000.0; 4462 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 4463 } 4464 4465 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 4466 // Process any discovered reference objects - we have 4467 // to do this _before_ we retire the GC alloc regions 4468 // as we may have to copy some 'reachable' referent 4469 // objects (and their reachable sub-graphs) that were 4470 // not copied during the pause. 4471 if (g1_policy()->should_process_references()) { 4472 preserve_cm_referents(per_thread_states); 4473 process_discovered_references(per_thread_states); 4474 } else { 4475 ref_processor_stw()->verify_no_references_recorded(); 4476 process_weak_jni_handles(); 4477 } 4478 4479 if (G1StringDedup::is_enabled()) { 4480 double fixup_start = os::elapsedTime(); 4481 4482 G1STWIsAliveClosure is_alive(this); 4483 G1KeepAliveClosure keep_alive(this); 4484 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times()); 4485 4486 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 4487 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms); 4488 } 4489 4490 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 4491 4492 if (evacuation_failed()) { 4493 restore_after_evac_failure(); 4494 4495 // Reset the G1EvacuationFailureALot counters and flags 4496 // Note: the values are reset only when an actual 4497 // evacuation failure occurs. 4498 NOT_PRODUCT(reset_evacuation_should_fail();) 4499 } 4500 4501 _preserved_marks_set.assert_empty(); 4502 4503 // Enqueue any remaining references remaining on the STW 4504 // reference processor's discovered lists. We need to do 4505 // this after the card table is cleaned (and verified) as 4506 // the act of enqueueing entries on to the pending list 4507 // will log these updates (and dirty their associated 4508 // cards). We need these updates logged to update any 4509 // RSets. 4510 if (g1_policy()->should_process_references()) { 4511 enqueue_discovered_references(per_thread_states); 4512 } else { 4513 g1_policy()->phase_times()->record_ref_enq_time(0); 4514 } 4515 4516 _allocator->release_gc_alloc_regions(evacuation_info); 4517 4518 merge_per_thread_state_info(per_thread_states); 4519 4520 // Reset and re-enable the hot card cache. 4521 // Note the counts for the cards in the regions in the 4522 // collection set are reset when the collection set is freed. 4523 _hot_card_cache->reset_hot_cache(); 4524 _hot_card_cache->set_use_cache(true); 4525 4526 purge_code_root_memory(); 4527 4528 redirty_logged_cards(); 4529 #if defined(COMPILER2) || INCLUDE_JVMCI 4530 DerivedPointerTable::update_pointers(); 4531 #endif 4532 g1_policy()->print_age_table(); 4533 } 4534 4535 void G1CollectedHeap::record_obj_copy_mem_stats() { 4536 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 4537 4538 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 4539 create_g1_evac_summary(&_old_evac_stats)); 4540 } 4541 4542 void G1CollectedHeap::free_region(HeapRegion* hr, 4543 FreeRegionList* free_list, 4544 bool skip_remset, 4545 bool skip_hot_card_cache, 4546 bool locked) { 4547 assert(!hr->is_free(), "the region should not be free"); 4548 assert(!hr->is_empty(), "the region should not be empty"); 4549 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 4550 assert(free_list != NULL, "pre-condition"); 4551 4552 if (G1VerifyBitmaps) { 4553 MemRegion mr(hr->bottom(), hr->end()); 4554 concurrent_mark()->clearRangePrevBitmap(mr); 4555 } 4556 4557 // Clear the card counts for this region. 4558 // Note: we only need to do this if the region is not young 4559 // (since we don't refine cards in young regions). 4560 if (!skip_hot_card_cache && !hr->is_young()) { 4561 _hot_card_cache->reset_card_counts(hr); 4562 } 4563 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 4564 free_list->add_ordered(hr); 4565 } 4566 4567 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4568 FreeRegionList* free_list, 4569 bool skip_remset) { 4570 assert(hr->is_humongous(), "this is only for humongous regions"); 4571 assert(free_list != NULL, "pre-condition"); 4572 hr->clear_humongous(); 4573 free_region(hr, free_list, skip_remset); 4574 } 4575 4576 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 4577 const uint humongous_regions_removed) { 4578 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 4579 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4580 _old_set.bulk_remove(old_regions_removed); 4581 _humongous_set.bulk_remove(humongous_regions_removed); 4582 } 4583 4584 } 4585 4586 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4587 assert(list != NULL, "list can't be null"); 4588 if (!list->is_empty()) { 4589 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4590 _hrm.insert_list_into_free_list(list); 4591 } 4592 } 4593 4594 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4595 decrease_used(bytes); 4596 } 4597 4598 class G1ParScrubRemSetTask: public AbstractGangTask { 4599 protected: 4600 G1RemSet* _g1rs; 4601 HeapRegionClaimer _hrclaimer; 4602 4603 public: 4604 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) : 4605 AbstractGangTask("G1 ScrubRS"), 4606 _g1rs(g1_rs), 4607 _hrclaimer(num_workers) { 4608 } 4609 4610 void work(uint worker_id) { 4611 _g1rs->scrub(worker_id, &_hrclaimer); 4612 } 4613 }; 4614 4615 void G1CollectedHeap::scrub_rem_set() { 4616 uint num_workers = workers()->active_workers(); 4617 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers); 4618 workers()->run_task(&g1_par_scrub_rs_task); 4619 } 4620 4621 class G1FreeCollectionSetTask : public AbstractGangTask { 4622 private: 4623 4624 // Closure applied to all regions in the collection set to do work that needs to 4625 // be done serially in a single thread. 4626 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 4627 private: 4628 EvacuationInfo* _evacuation_info; 4629 const size_t* _surviving_young_words; 4630 4631 // Bytes used in successfully evacuated regions before the evacuation. 4632 size_t _before_used_bytes; 4633 // Bytes used in unsucessfully evacuated regions before the evacuation 4634 size_t _after_used_bytes; 4635 4636 size_t _bytes_allocated_in_old_since_last_gc; 4637 4638 size_t _failure_used_words; 4639 size_t _failure_waste_words; 4640 4641 FreeRegionList _local_free_list; 4642 public: 4643 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4644 HeapRegionClosure(), 4645 _evacuation_info(evacuation_info), 4646 _surviving_young_words(surviving_young_words), 4647 _before_used_bytes(0), 4648 _after_used_bytes(0), 4649 _bytes_allocated_in_old_since_last_gc(0), 4650 _failure_used_words(0), 4651 _failure_waste_words(0), 4652 _local_free_list("Local Region List for CSet Freeing") { 4653 } 4654 4655 virtual bool doHeapRegion(HeapRegion* r) { 4656 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4657 4658 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 4659 g1h->clear_in_cset(r); 4660 4661 if (r->is_young()) { 4662 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(), 4663 "Young index %d is wrong for region %u of type %s with %u young regions", 4664 r->young_index_in_cset(), 4665 r->hrm_index(), 4666 r->get_type_str(), 4667 g1h->collection_set()->young_region_length()); 4668 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 4669 r->record_surv_words_in_group(words_survived); 4670 } 4671 4672 if (!r->evacuation_failed()) { 4673 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4674 _before_used_bytes += r->used(); 4675 g1h->free_region(r, 4676 &_local_free_list, 4677 true, /* skip_remset */ 4678 true, /* skip_hot_card_cache */ 4679 true /* locked */); 4680 } else { 4681 r->uninstall_surv_rate_group(); 4682 r->set_young_index_in_cset(-1); 4683 r->set_evacuation_failed(false); 4684 // When moving a young gen region to old gen, we "allocate" that whole region 4685 // there. This is in addition to any already evacuated objects. Notify the 4686 // policy about that. 4687 // Old gen regions do not cause an additional allocation: both the objects 4688 // still in the region and the ones already moved are accounted for elsewhere. 4689 if (r->is_young()) { 4690 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4691 } 4692 // The region is now considered to be old. 4693 r->set_old(); 4694 // Do some allocation statistics accounting. Regions that failed evacuation 4695 // are always made old, so there is no need to update anything in the young 4696 // gen statistics, but we need to update old gen statistics. 4697 size_t used_words = r->marked_bytes() / HeapWordSize; 4698 4699 _failure_used_words += used_words; 4700 _failure_waste_words += HeapRegion::GrainWords - used_words; 4701 4702 g1h->old_set_add(r); 4703 _after_used_bytes += r->used(); 4704 } 4705 return false; 4706 } 4707 4708 void complete_work() { 4709 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4710 4711 _evacuation_info->set_regions_freed(_local_free_list.length()); 4712 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4713 4714 g1h->prepend_to_freelist(&_local_free_list); 4715 g1h->decrement_summary_bytes(_before_used_bytes); 4716 4717 G1Policy* policy = g1h->g1_policy(); 4718 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4719 4720 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4721 } 4722 }; 4723 4724 G1CollectionSet* _collection_set; 4725 G1SerialFreeCollectionSetClosure _cl; 4726 const size_t* _surviving_young_words; 4727 4728 size_t _rs_lengths; 4729 4730 volatile jint _serial_work_claim; 4731 4732 struct WorkItem { 4733 uint region_idx; 4734 bool is_young; 4735 bool evacuation_failed; 4736 4737 WorkItem(HeapRegion* r) { 4738 region_idx = r->hrm_index(); 4739 is_young = r->is_young(); 4740 evacuation_failed = r->evacuation_failed(); 4741 } 4742 }; 4743 4744 volatile size_t _parallel_work_claim; 4745 size_t _num_work_items; 4746 WorkItem* _work_items; 4747 4748 void do_serial_work() { 4749 // Need to grab the lock to be allowed to modify the old region list. 4750 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4751 _collection_set->iterate(&_cl); 4752 } 4753 4754 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4755 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4756 4757 HeapRegion* r = g1h->region_at(region_idx); 4758 assert(!g1h->is_on_master_free_list(r), "sanity"); 4759 4760 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths); 4761 4762 if (!is_young) { 4763 g1h->_hot_card_cache->reset_card_counts(r); 4764 } 4765 4766 if (!evacuation_failed) { 4767 r->rem_set()->clear_locked(); 4768 } 4769 } 4770 4771 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4772 private: 4773 size_t _cur_idx; 4774 WorkItem* _work_items; 4775 public: 4776 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4777 4778 virtual bool doHeapRegion(HeapRegion* r) { 4779 _work_items[_cur_idx++] = WorkItem(r); 4780 return false; 4781 } 4782 }; 4783 4784 void prepare_work() { 4785 G1PrepareFreeCollectionSetClosure cl(_work_items); 4786 _collection_set->iterate(&cl); 4787 } 4788 4789 void complete_work() { 4790 _cl.complete_work(); 4791 4792 G1Policy* policy = G1CollectedHeap::heap()->g1_policy(); 4793 policy->record_max_rs_lengths(_rs_lengths); 4794 policy->cset_regions_freed(); 4795 } 4796 public: 4797 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4798 AbstractGangTask("G1 Free Collection Set"), 4799 _cl(evacuation_info, surviving_young_words), 4800 _collection_set(collection_set), 4801 _surviving_young_words(surviving_young_words), 4802 _serial_work_claim(0), 4803 _rs_lengths(0), 4804 _parallel_work_claim(0), 4805 _num_work_items(collection_set->region_length()), 4806 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4807 prepare_work(); 4808 } 4809 4810 ~G1FreeCollectionSetTask() { 4811 complete_work(); 4812 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4813 } 4814 4815 // Chunk size for work distribution. The chosen value has been determined experimentally 4816 // to be a good tradeoff between overhead and achievable parallelism. 4817 static uint chunk_size() { return 32; } 4818 4819 virtual void work(uint worker_id) { 4820 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4821 4822 // Claim serial work. 4823 if (_serial_work_claim == 0) { 4824 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4825 if (value == 0) { 4826 double serial_time = os::elapsedTime(); 4827 do_serial_work(); 4828 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4829 } 4830 } 4831 4832 // Start parallel work. 4833 double young_time = 0.0; 4834 bool has_young_time = false; 4835 double non_young_time = 0.0; 4836 bool has_non_young_time = false; 4837 4838 while (true) { 4839 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4840 size_t cur = end - chunk_size(); 4841 4842 if (cur >= _num_work_items) { 4843 break; 4844 } 4845 4846 double start_time = os::elapsedTime(); 4847 4848 end = MIN2(end, _num_work_items); 4849 4850 for (; cur < end; cur++) { 4851 bool is_young = _work_items[cur].is_young; 4852 4853 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4854 4855 double end_time = os::elapsedTime(); 4856 double time_taken = end_time - start_time; 4857 if (is_young) { 4858 young_time += time_taken; 4859 has_young_time = true; 4860 } else { 4861 non_young_time += time_taken; 4862 has_non_young_time = true; 4863 } 4864 start_time = end_time; 4865 } 4866 } 4867 4868 if (has_young_time) { 4869 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4870 } 4871 if (has_non_young_time) { 4872 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time); 4873 } 4874 } 4875 }; 4876 4877 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4878 _eden.clear(); 4879 4880 double free_cset_start_time = os::elapsedTime(); 4881 4882 { 4883 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U); 4884 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4885 4886 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4887 4888 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4889 cl.name(), 4890 num_workers, 4891 _collection_set.region_length()); 4892 workers()->run_task(&cl, num_workers); 4893 } 4894 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4895 4896 collection_set->clear(); 4897 } 4898 4899 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4900 private: 4901 FreeRegionList* _free_region_list; 4902 HeapRegionSet* _proxy_set; 4903 uint _humongous_regions_removed; 4904 size_t _freed_bytes; 4905 public: 4906 4907 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4908 _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) { 4909 } 4910 4911 virtual bool doHeapRegion(HeapRegion* r) { 4912 if (!r->is_starts_humongous()) { 4913 return false; 4914 } 4915 4916 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4917 4918 oop obj = (oop)r->bottom(); 4919 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 4920 4921 // The following checks whether the humongous object is live are sufficient. 4922 // The main additional check (in addition to having a reference from the roots 4923 // or the young gen) is whether the humongous object has a remembered set entry. 4924 // 4925 // A humongous object cannot be live if there is no remembered set for it 4926 // because: 4927 // - there can be no references from within humongous starts regions referencing 4928 // the object because we never allocate other objects into them. 4929 // (I.e. there are no intra-region references that may be missed by the 4930 // remembered set) 4931 // - as soon there is a remembered set entry to the humongous starts region 4932 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4933 // until the end of a concurrent mark. 4934 // 4935 // It is not required to check whether the object has been found dead by marking 4936 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4937 // all objects allocated during that time are considered live. 4938 // SATB marking is even more conservative than the remembered set. 4939 // So if at this point in the collection there is no remembered set entry, 4940 // nobody has a reference to it. 4941 // At the start of collection we flush all refinement logs, and remembered sets 4942 // are completely up-to-date wrt to references to the humongous object. 4943 // 4944 // Other implementation considerations: 4945 // - never consider object arrays at this time because they would pose 4946 // considerable effort for cleaning up the the remembered sets. This is 4947 // required because stale remembered sets might reference locations that 4948 // are currently allocated into. 4949 uint region_idx = r->hrm_index(); 4950 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4951 !r->rem_set()->is_empty()) { 4952 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", 4953 region_idx, 4954 (size_t)obj->size() * HeapWordSize, 4955 p2i(r->bottom()), 4956 r->rem_set()->occupied(), 4957 r->rem_set()->strong_code_roots_list_length(), 4958 next_bitmap->isMarked(r->bottom()), 4959 g1h->is_humongous_reclaim_candidate(region_idx), 4960 obj->is_typeArray() 4961 ); 4962 return false; 4963 } 4964 4965 guarantee(obj->is_typeArray(), 4966 "Only eagerly reclaiming type arrays is supported, but the object " 4967 PTR_FORMAT " is not.", p2i(r->bottom())); 4968 4969 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", 4970 region_idx, 4971 (size_t)obj->size() * HeapWordSize, 4972 p2i(r->bottom()), 4973 r->rem_set()->occupied(), 4974 r->rem_set()->strong_code_roots_list_length(), 4975 next_bitmap->isMarked(r->bottom()), 4976 g1h->is_humongous_reclaim_candidate(region_idx), 4977 obj->is_typeArray() 4978 ); 4979 4980 // Need to clear mark bit of the humongous object if already set. 4981 if (next_bitmap->isMarked(r->bottom())) { 4982 next_bitmap->clear(r->bottom()); 4983 } 4984 do { 4985 HeapRegion* next = g1h->next_region_in_humongous(r); 4986 _freed_bytes += r->used(); 4987 r->set_containing_set(NULL); 4988 _humongous_regions_removed++; 4989 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ ); 4990 r = next; 4991 } while (r != NULL); 4992 4993 return false; 4994 } 4995 4996 uint humongous_free_count() { 4997 return _humongous_regions_removed; 4998 } 4999 5000 size_t bytes_freed() const { 5001 return _freed_bytes; 5002 } 5003 }; 5004 5005 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 5006 assert_at_safepoint(true); 5007 5008 if (!G1EagerReclaimHumongousObjects || 5009 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 5010 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 5011 return; 5012 } 5013 5014 double start_time = os::elapsedTime(); 5015 5016 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 5017 5018 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 5019 heap_region_iterate(&cl); 5020 5021 remove_from_old_sets(0, cl.humongous_free_count()); 5022 5023 G1HRPrinter* hrp = hr_printer(); 5024 if (hrp->is_active()) { 5025 FreeRegionListIterator iter(&local_cleanup_list); 5026 while (iter.more_available()) { 5027 HeapRegion* hr = iter.get_next(); 5028 hrp->cleanup(hr); 5029 } 5030 } 5031 5032 prepend_to_freelist(&local_cleanup_list); 5033 decrement_summary_bytes(cl.bytes_freed()); 5034 5035 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 5036 cl.humongous_free_count()); 5037 } 5038 5039 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 5040 public: 5041 virtual bool doHeapRegion(HeapRegion* r) { 5042 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 5043 G1CollectedHeap::heap()->clear_in_cset(r); 5044 r->set_young_index_in_cset(-1); 5045 return false; 5046 } 5047 }; 5048 5049 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 5050 G1AbandonCollectionSetClosure cl; 5051 collection_set->iterate(&cl); 5052 5053 collection_set->clear(); 5054 collection_set->stop_incremental_building(); 5055 } 5056 5057 void G1CollectedHeap::set_free_regions_coming() { 5058 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming"); 5059 5060 assert(!free_regions_coming(), "pre-condition"); 5061 _free_regions_coming = true; 5062 } 5063 5064 void G1CollectedHeap::reset_free_regions_coming() { 5065 assert(free_regions_coming(), "pre-condition"); 5066 5067 { 5068 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5069 _free_regions_coming = false; 5070 SecondaryFreeList_lock->notify_all(); 5071 } 5072 5073 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming"); 5074 } 5075 5076 void G1CollectedHeap::wait_while_free_regions_coming() { 5077 // Most of the time we won't have to wait, so let's do a quick test 5078 // first before we take the lock. 5079 if (!free_regions_coming()) { 5080 return; 5081 } 5082 5083 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions"); 5084 5085 { 5086 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5087 while (free_regions_coming()) { 5088 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 5089 } 5090 } 5091 5092 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions"); 5093 } 5094 5095 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 5096 return _allocator->is_retained_old_region(hr); 5097 } 5098 5099 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 5100 _eden.add(hr); 5101 _g1_policy->set_region_eden(hr); 5102 } 5103 5104 #ifdef ASSERT 5105 5106 class NoYoungRegionsClosure: public HeapRegionClosure { 5107 private: 5108 bool _success; 5109 public: 5110 NoYoungRegionsClosure() : _success(true) { } 5111 bool doHeapRegion(HeapRegion* r) { 5112 if (r->is_young()) { 5113 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 5114 p2i(r->bottom()), p2i(r->end())); 5115 _success = false; 5116 } 5117 return false; 5118 } 5119 bool success() { return _success; } 5120 }; 5121 5122 bool G1CollectedHeap::check_young_list_empty() { 5123 bool ret = (young_regions_count() == 0); 5124 5125 NoYoungRegionsClosure closure; 5126 heap_region_iterate(&closure); 5127 ret = ret && closure.success(); 5128 5129 return ret; 5130 } 5131 5132 #endif // ASSERT 5133 5134 class TearDownRegionSetsClosure : public HeapRegionClosure { 5135 private: 5136 HeapRegionSet *_old_set; 5137 5138 public: 5139 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 5140 5141 bool doHeapRegion(HeapRegion* r) { 5142 if (r->is_old()) { 5143 _old_set->remove(r); 5144 } else if(r->is_young()) { 5145 r->uninstall_surv_rate_group(); 5146 } else { 5147 // We ignore free regions, we'll empty the free list afterwards. 5148 // We ignore humongous regions, we're not tearing down the 5149 // humongous regions set. 5150 assert(r->is_free() || r->is_humongous(), 5151 "it cannot be another type"); 5152 } 5153 return false; 5154 } 5155 5156 ~TearDownRegionSetsClosure() { 5157 assert(_old_set->is_empty(), "post-condition"); 5158 } 5159 }; 5160 5161 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 5162 assert_at_safepoint(true /* should_be_vm_thread */); 5163 5164 if (!free_list_only) { 5165 TearDownRegionSetsClosure cl(&_old_set); 5166 heap_region_iterate(&cl); 5167 5168 // Note that emptying the _young_list is postponed and instead done as 5169 // the first step when rebuilding the regions sets again. The reason for 5170 // this is that during a full GC string deduplication needs to know if 5171 // a collected region was young or old when the full GC was initiated. 5172 } 5173 _hrm.remove_all_free_regions(); 5174 } 5175 5176 void G1CollectedHeap::increase_used(size_t bytes) { 5177 _summary_bytes_used += bytes; 5178 } 5179 5180 void G1CollectedHeap::decrease_used(size_t bytes) { 5181 assert(_summary_bytes_used >= bytes, 5182 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 5183 _summary_bytes_used, bytes); 5184 _summary_bytes_used -= bytes; 5185 } 5186 5187 void G1CollectedHeap::set_used(size_t bytes) { 5188 _summary_bytes_used = bytes; 5189 } 5190 5191 class RebuildRegionSetsClosure : public HeapRegionClosure { 5192 private: 5193 bool _free_list_only; 5194 HeapRegionSet* _old_set; 5195 HeapRegionManager* _hrm; 5196 size_t _total_used; 5197 5198 public: 5199 RebuildRegionSetsClosure(bool free_list_only, 5200 HeapRegionSet* old_set, HeapRegionManager* hrm) : 5201 _free_list_only(free_list_only), 5202 _old_set(old_set), _hrm(hrm), _total_used(0) { 5203 assert(_hrm->num_free_regions() == 0, "pre-condition"); 5204 if (!free_list_only) { 5205 assert(_old_set->is_empty(), "pre-condition"); 5206 } 5207 } 5208 5209 bool doHeapRegion(HeapRegion* r) { 5210 if (r->is_empty()) { 5211 // Add free regions to the free list 5212 r->set_free(); 5213 r->set_allocation_context(AllocationContext::system()); 5214 _hrm->insert_into_free_list(r); 5215 } else if (!_free_list_only) { 5216 5217 if (r->is_humongous()) { 5218 // We ignore humongous regions. We left the humongous set unchanged. 5219 } else { 5220 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 5221 // We now consider all regions old, so register as such. Leave 5222 // archive regions set that way, however, while still adding 5223 // them to the old set. 5224 if (!r->is_archive()) { 5225 r->set_old(); 5226 } 5227 _old_set->add(r); 5228 } 5229 _total_used += r->used(); 5230 } 5231 5232 return false; 5233 } 5234 5235 size_t total_used() { 5236 return _total_used; 5237 } 5238 }; 5239 5240 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 5241 assert_at_safepoint(true /* should_be_vm_thread */); 5242 5243 if (!free_list_only) { 5244 _eden.clear(); 5245 _survivor.clear(); 5246 } 5247 5248 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 5249 heap_region_iterate(&cl); 5250 5251 if (!free_list_only) { 5252 set_used(cl.total_used()); 5253 if (_archive_allocator != NULL) { 5254 _archive_allocator->clear_used(); 5255 } 5256 } 5257 assert(used_unlocked() == recalculate_used(), 5258 "inconsistent used_unlocked(), " 5259 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 5260 used_unlocked(), recalculate_used()); 5261 } 5262 5263 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 5264 _refine_cte_cl->set_concurrent(concurrent); 5265 } 5266 5267 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 5268 HeapRegion* hr = heap_region_containing(p); 5269 return hr->is_in(p); 5270 } 5271 5272 // Methods for the mutator alloc region 5273 5274 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 5275 bool force) { 5276 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 5277 assert(!force || g1_policy()->can_expand_young_list(), 5278 "if force is true we should be able to expand the young list"); 5279 bool should_allocate = g1_policy()->should_allocate_mutator_region(); 5280 if (force || should_allocate) { 5281 HeapRegion* new_alloc_region = new_region(word_size, 5282 false /* is_old */, 5283 false /* do_expand */); 5284 if (new_alloc_region != NULL) { 5285 set_region_short_lived_locked(new_alloc_region); 5286 _hr_printer.alloc(new_alloc_region, !should_allocate); 5287 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 5288 return new_alloc_region; 5289 } 5290 } 5291 return NULL; 5292 } 5293 5294 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 5295 size_t allocated_bytes) { 5296 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 5297 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 5298 5299 collection_set()->add_eden_region(alloc_region); 5300 increase_used(allocated_bytes); 5301 _hr_printer.retire(alloc_region); 5302 // We update the eden sizes here, when the region is retired, 5303 // instead of when it's allocated, since this is the point that its 5304 // used space has been recored in _summary_bytes_used. 5305 g1mm()->update_eden_size(); 5306 } 5307 5308 // Methods for the GC alloc regions 5309 5310 bool G1CollectedHeap::has_more_regions(InCSetState dest) { 5311 if (dest.is_old()) { 5312 return true; 5313 } else { 5314 return survivor_regions_count() < g1_policy()->max_survivor_regions(); 5315 } 5316 } 5317 5318 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) { 5319 assert(FreeList_lock->owned_by_self(), "pre-condition"); 5320 5321 if (!has_more_regions(dest)) { 5322 return NULL; 5323 } 5324 5325 const bool is_survivor = dest.is_young(); 5326 5327 HeapRegion* new_alloc_region = new_region(word_size, 5328 !is_survivor, 5329 true /* do_expand */); 5330 if (new_alloc_region != NULL) { 5331 // We really only need to do this for old regions given that we 5332 // should never scan survivors. But it doesn't hurt to do it 5333 // for survivors too. 5334 new_alloc_region->record_timestamp(); 5335 if (is_survivor) { 5336 new_alloc_region->set_survivor(); 5337 _survivor.add(new_alloc_region); 5338 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 5339 } else { 5340 new_alloc_region->set_old(); 5341 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 5342 } 5343 _hr_printer.alloc(new_alloc_region); 5344 bool during_im = collector_state()->during_initial_mark_pause(); 5345 new_alloc_region->note_start_of_copying(during_im); 5346 return new_alloc_region; 5347 } 5348 return NULL; 5349 } 5350 5351 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 5352 size_t allocated_bytes, 5353 InCSetState dest) { 5354 bool during_im = collector_state()->during_initial_mark_pause(); 5355 alloc_region->note_end_of_copying(during_im); 5356 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 5357 if (dest.is_old()) { 5358 _old_set.add(alloc_region); 5359 } 5360 _hr_printer.retire(alloc_region); 5361 } 5362 5363 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 5364 bool expanded = false; 5365 uint index = _hrm.find_highest_free(&expanded); 5366 5367 if (index != G1_NO_HRM_INDEX) { 5368 if (expanded) { 5369 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 5370 HeapRegion::GrainWords * HeapWordSize); 5371 } 5372 _hrm.allocate_free_regions_starting_at(index, 1); 5373 return region_at(index); 5374 } 5375 return NULL; 5376 } 5377 5378 // Optimized nmethod scanning 5379 5380 class RegisterNMethodOopClosure: public OopClosure { 5381 G1CollectedHeap* _g1h; 5382 nmethod* _nm; 5383 5384 template <class T> void do_oop_work(T* p) { 5385 T heap_oop = oopDesc::load_heap_oop(p); 5386 if (!oopDesc::is_null(heap_oop)) { 5387 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 5388 HeapRegion* hr = _g1h->heap_region_containing(obj); 5389 assert(!hr->is_continues_humongous(), 5390 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 5391 " starting at " HR_FORMAT, 5392 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 5393 5394 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 5395 hr->add_strong_code_root_locked(_nm); 5396 } 5397 } 5398 5399 public: 5400 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 5401 _g1h(g1h), _nm(nm) {} 5402 5403 void do_oop(oop* p) { do_oop_work(p); } 5404 void do_oop(narrowOop* p) { do_oop_work(p); } 5405 }; 5406 5407 class UnregisterNMethodOopClosure: public OopClosure { 5408 G1CollectedHeap* _g1h; 5409 nmethod* _nm; 5410 5411 template <class T> void do_oop_work(T* p) { 5412 T heap_oop = oopDesc::load_heap_oop(p); 5413 if (!oopDesc::is_null(heap_oop)) { 5414 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 5415 HeapRegion* hr = _g1h->heap_region_containing(obj); 5416 assert(!hr->is_continues_humongous(), 5417 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 5418 " starting at " HR_FORMAT, 5419 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 5420 5421 hr->remove_strong_code_root(_nm); 5422 } 5423 } 5424 5425 public: 5426 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 5427 _g1h(g1h), _nm(nm) {} 5428 5429 void do_oop(oop* p) { do_oop_work(p); } 5430 void do_oop(narrowOop* p) { do_oop_work(p); } 5431 }; 5432 5433 void G1CollectedHeap::register_nmethod(nmethod* nm) { 5434 CollectedHeap::register_nmethod(nm); 5435 5436 guarantee(nm != NULL, "sanity"); 5437 RegisterNMethodOopClosure reg_cl(this, nm); 5438 nm->oops_do(®_cl); 5439 } 5440 5441 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 5442 CollectedHeap::unregister_nmethod(nm); 5443 5444 guarantee(nm != NULL, "sanity"); 5445 UnregisterNMethodOopClosure reg_cl(this, nm); 5446 nm->oops_do(®_cl, true); 5447 } 5448 5449 void G1CollectedHeap::purge_code_root_memory() { 5450 double purge_start = os::elapsedTime(); 5451 G1CodeRootSet::purge(); 5452 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 5453 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 5454 } 5455 5456 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 5457 G1CollectedHeap* _g1h; 5458 5459 public: 5460 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 5461 _g1h(g1h) {} 5462 5463 void do_code_blob(CodeBlob* cb) { 5464 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 5465 if (nm == NULL) { 5466 return; 5467 } 5468 5469 if (ScavengeRootsInCode) { 5470 _g1h->register_nmethod(nm); 5471 } 5472 } 5473 }; 5474 5475 void G1CollectedHeap::rebuild_strong_code_roots() { 5476 RebuildStrongCodeRootClosure blob_cl(this); 5477 CodeCache::blobs_do(&blob_cl); 5478 }