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/g1MarkSweep.hpp" 46 #include "gc/g1/g1OopClosures.inline.hpp" 47 #include "gc/g1/g1ParScanThreadState.inline.hpp" 48 #include "gc/g1/g1RegionToSpaceMapper.hpp" 49 #include "gc/g1/g1RemSet.inline.hpp" 50 #include "gc/g1/g1RootClosures.hpp" 51 #include "gc/g1/g1RootProcessor.hpp" 52 #include "gc/g1/g1StringDedup.hpp" 53 #include "gc/g1/g1YCTypes.hpp" 54 #include "gc/g1/heapRegion.inline.hpp" 55 #include "gc/g1/heapRegionRemSet.hpp" 56 #include "gc/g1/heapRegionSet.inline.hpp" 57 #include "gc/g1/suspendibleThreadSet.hpp" 58 #include "gc/g1/vm_operations_g1.hpp" 59 #include "gc/shared/gcHeapSummary.hpp" 60 #include "gc/shared/gcId.hpp" 61 #include "gc/shared/gcLocker.inline.hpp" 62 #include "gc/shared/gcTimer.hpp" 63 #include "gc/shared/gcTrace.hpp" 64 #include "gc/shared/gcTraceTime.inline.hpp" 65 #include "gc/shared/generationSpec.hpp" 66 #include "gc/shared/isGCActiveMark.hpp" 67 #include "gc/shared/referenceProcessor.inline.hpp" 68 #include "gc/shared/taskqueue.inline.hpp" 69 #include "logging/log.hpp" 70 #include "memory/allocation.hpp" 71 #include "memory/iterator.hpp" 72 #include "memory/resourceArea.hpp" 73 #include "oops/oop.inline.hpp" 74 #include "runtime/atomic.inline.hpp" 75 #include "runtime/init.hpp" 76 #include "runtime/orderAccess.inline.hpp" 77 #include "runtime/vmThread.hpp" 78 #include "utilities/globalDefinitions.hpp" 79 #include "utilities/stack.inline.hpp" 80 81 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 82 83 // INVARIANTS/NOTES 84 // 85 // All allocation activity covered by the G1CollectedHeap interface is 86 // serialized by acquiring the HeapLock. This happens in mem_allocate 87 // and allocate_new_tlab, which are the "entry" points to the 88 // allocation code from the rest of the JVM. (Note that this does not 89 // apply to TLAB allocation, which is not part of this interface: it 90 // is done by clients of this interface.) 91 92 // Local to this file. 93 94 class RefineCardTableEntryClosure: public CardTableEntryClosure { 95 bool _concurrent; 96 public: 97 RefineCardTableEntryClosure() : _concurrent(true) { } 98 99 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 100 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 101 // This path is executed by the concurrent refine or mutator threads, 102 // concurrently, and so we do not care if card_ptr contains references 103 // that point into the collection set. 104 assert(!oops_into_cset, "should be"); 105 106 if (_concurrent && SuspendibleThreadSet::should_yield()) { 107 // Caller will actually yield. 108 return false; 109 } 110 // Otherwise, we finished successfully; return true. 111 return true; 112 } 113 114 void set_concurrent(bool b) { _concurrent = b; } 115 }; 116 117 118 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 119 private: 120 size_t _num_dirtied; 121 G1CollectedHeap* _g1h; 122 G1SATBCardTableLoggingModRefBS* _g1_bs; 123 124 HeapRegion* region_for_card(jbyte* card_ptr) const { 125 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr)); 126 } 127 128 bool will_become_free(HeapRegion* hr) const { 129 // A region will be freed by free_collection_set if the region is in the 130 // collection set and has not had an evacuation failure. 131 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 132 } 133 134 public: 135 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(), 136 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { } 137 138 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 139 HeapRegion* hr = region_for_card(card_ptr); 140 141 // Should only dirty cards in regions that won't be freed. 142 if (!will_become_free(hr)) { 143 *card_ptr = CardTableModRefBS::dirty_card_val(); 144 _num_dirtied++; 145 } 146 147 return true; 148 } 149 150 size_t num_dirtied() const { return _num_dirtied; } 151 }; 152 153 154 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 155 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 156 } 157 158 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 159 // The from card cache is not the memory that is actually committed. So we cannot 160 // take advantage of the zero_filled parameter. 161 reset_from_card_cache(start_idx, num_regions); 162 } 163 164 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 165 { 166 // Claim the right to put the region on the dirty cards region list 167 // by installing a self pointer. 168 HeapRegion* next = hr->get_next_dirty_cards_region(); 169 if (next == NULL) { 170 HeapRegion* res = (HeapRegion*) 171 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 172 NULL); 173 if (res == NULL) { 174 HeapRegion* head; 175 do { 176 // Put the region to the dirty cards region list. 177 head = _dirty_cards_region_list; 178 next = (HeapRegion*) 179 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 180 if (next == head) { 181 assert(hr->get_next_dirty_cards_region() == hr, 182 "hr->get_next_dirty_cards_region() != hr"); 183 if (next == NULL) { 184 // The last region in the list points to itself. 185 hr->set_next_dirty_cards_region(hr); 186 } else { 187 hr->set_next_dirty_cards_region(next); 188 } 189 } 190 } while (next != head); 191 } 192 } 193 } 194 195 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 196 { 197 HeapRegion* head; 198 HeapRegion* hr; 199 do { 200 head = _dirty_cards_region_list; 201 if (head == NULL) { 202 return NULL; 203 } 204 HeapRegion* new_head = head->get_next_dirty_cards_region(); 205 if (head == new_head) { 206 // The last region. 207 new_head = NULL; 208 } 209 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 210 head); 211 } while (hr != head); 212 assert(hr != NULL, "invariant"); 213 hr->set_next_dirty_cards_region(NULL); 214 return hr; 215 } 216 217 // Returns true if the reference points to an object that 218 // can move in an incremental collection. 219 bool G1CollectedHeap::is_scavengable(const void* p) { 220 HeapRegion* hr = heap_region_containing(p); 221 return !hr->is_pinned(); 222 } 223 224 // Private methods. 225 226 HeapRegion* 227 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 228 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 229 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 230 if (!_secondary_free_list.is_empty()) { 231 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 232 "secondary_free_list has %u entries", 233 _secondary_free_list.length()); 234 // It looks as if there are free regions available on the 235 // secondary_free_list. Let's move them to the free_list and try 236 // again to allocate from it. 237 append_secondary_free_list(); 238 239 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 240 "empty we should have moved at least one entry to the free_list"); 241 HeapRegion* res = _hrm.allocate_free_region(is_old); 242 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 243 "allocated " HR_FORMAT " from secondary_free_list", 244 HR_FORMAT_PARAMS(res)); 245 return res; 246 } 247 248 // Wait here until we get notified either when (a) there are no 249 // more free regions coming or (b) some regions have been moved on 250 // the secondary_free_list. 251 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 252 } 253 254 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 255 "could not allocate from secondary_free_list"); 256 return NULL; 257 } 258 259 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 260 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 261 "the only time we use this to allocate a humongous region is " 262 "when we are allocating a single humongous region"); 263 264 HeapRegion* res; 265 if (G1StressConcRegionFreeing) { 266 if (!_secondary_free_list.is_empty()) { 267 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 268 "forced to look at the secondary_free_list"); 269 res = new_region_try_secondary_free_list(is_old); 270 if (res != NULL) { 271 return res; 272 } 273 } 274 } 275 276 res = _hrm.allocate_free_region(is_old); 277 278 if (res == NULL) { 279 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 280 "res == NULL, trying the secondary_free_list"); 281 res = new_region_try_secondary_free_list(is_old); 282 } 283 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 284 // Currently, only attempts to allocate GC alloc regions set 285 // do_expand to true. So, we should only reach here during a 286 // safepoint. If this assumption changes we might have to 287 // reconsider the use of _expand_heap_after_alloc_failure. 288 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 289 290 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 291 word_size * HeapWordSize); 292 293 if (expand(word_size * HeapWordSize)) { 294 // Given that expand() succeeded in expanding the heap, and we 295 // always expand the heap by an amount aligned to the heap 296 // region size, the free list should in theory not be empty. 297 // In either case allocate_free_region() will check for NULL. 298 res = _hrm.allocate_free_region(is_old); 299 } else { 300 _expand_heap_after_alloc_failure = false; 301 } 302 } 303 return res; 304 } 305 306 HeapWord* 307 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 308 uint num_regions, 309 size_t word_size, 310 AllocationContext_t context) { 311 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 312 assert(is_humongous(word_size), "word_size should be humongous"); 313 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 314 315 // Index of last region in the series. 316 uint last = first + num_regions - 1; 317 318 // We need to initialize the region(s) we just discovered. This is 319 // a bit tricky given that it can happen concurrently with 320 // refinement threads refining cards on these regions and 321 // potentially wanting to refine the BOT as they are scanning 322 // those cards (this can happen shortly after a cleanup; see CR 323 // 6991377). So we have to set up the region(s) carefully and in 324 // a specific order. 325 326 // The word size sum of all the regions we will allocate. 327 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 328 assert(word_size <= word_size_sum, "sanity"); 329 330 // This will be the "starts humongous" region. 331 HeapRegion* first_hr = region_at(first); 332 // The header of the new object will be placed at the bottom of 333 // the first region. 334 HeapWord* new_obj = first_hr->bottom(); 335 // This will be the new top of the new object. 336 HeapWord* obj_top = new_obj + word_size; 337 338 // First, we need to zero the header of the space that we will be 339 // allocating. When we update top further down, some refinement 340 // threads might try to scan the region. By zeroing the header we 341 // ensure that any thread that will try to scan the region will 342 // come across the zero klass word and bail out. 343 // 344 // NOTE: It would not have been correct to have used 345 // CollectedHeap::fill_with_object() and make the space look like 346 // an int array. The thread that is doing the allocation will 347 // later update the object header to a potentially different array 348 // type and, for a very short period of time, the klass and length 349 // fields will be inconsistent. This could cause a refinement 350 // thread to calculate the object size incorrectly. 351 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 352 353 // How many words we use for filler objects. 354 size_t word_fill_size = word_size_sum - word_size; 355 356 // How many words memory we "waste" which cannot hold a filler object. 357 size_t words_not_fillable = 0; 358 359 if (word_fill_size >= min_fill_size()) { 360 fill_with_objects(obj_top, word_fill_size); 361 } else if (word_fill_size > 0) { 362 // We have space to fill, but we cannot fit an object there. 363 words_not_fillable = word_fill_size; 364 word_fill_size = 0; 365 } 366 367 // We will set up the first region as "starts humongous". This 368 // will also update the BOT covering all the regions to reflect 369 // that there is a single object that starts at the bottom of the 370 // first region. 371 first_hr->set_starts_humongous(obj_top, word_fill_size); 372 first_hr->set_allocation_context(context); 373 // Then, if there are any, we will set up the "continues 374 // humongous" regions. 375 HeapRegion* hr = NULL; 376 for (uint i = first + 1; i <= last; ++i) { 377 hr = region_at(i); 378 hr->set_continues_humongous(first_hr); 379 hr->set_allocation_context(context); 380 } 381 382 // Up to this point no concurrent thread would have been able to 383 // do any scanning on any region in this series. All the top 384 // fields still point to bottom, so the intersection between 385 // [bottom,top] and [card_start,card_end] will be empty. Before we 386 // update the top fields, we'll do a storestore to make sure that 387 // no thread sees the update to top before the zeroing of the 388 // object header and the BOT initialization. 389 OrderAccess::storestore(); 390 391 // Now, we will update the top fields of the "continues humongous" 392 // regions except the last one. 393 for (uint i = first; i < last; ++i) { 394 hr = region_at(i); 395 hr->set_top(hr->end()); 396 } 397 398 hr = region_at(last); 399 // If we cannot fit a filler object, we must set top to the end 400 // of the humongous object, otherwise we cannot iterate the heap 401 // and the BOT will not be complete. 402 hr->set_top(hr->end() - words_not_fillable); 403 404 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 405 "obj_top should be in last region"); 406 407 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 408 409 assert(words_not_fillable == 0 || 410 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 411 "Miscalculation in humongous allocation"); 412 413 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 414 415 for (uint i = first; i <= last; ++i) { 416 hr = region_at(i); 417 _humongous_set.add(hr); 418 _hr_printer.alloc(hr); 419 } 420 421 return new_obj; 422 } 423 424 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 425 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 426 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 427 } 428 429 // If could fit into free regions w/o expansion, try. 430 // Otherwise, if can expand, do so. 431 // Otherwise, if using ex regions might help, try with ex given back. 432 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 433 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 434 435 _verifier->verify_region_sets_optional(); 436 437 uint first = G1_NO_HRM_INDEX; 438 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 439 440 if (obj_regions == 1) { 441 // Only one region to allocate, try to use a fast path by directly allocating 442 // from the free lists. Do not try to expand here, we will potentially do that 443 // later. 444 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 445 if (hr != NULL) { 446 first = hr->hrm_index(); 447 } 448 } else { 449 // We can't allocate humongous regions spanning more than one region while 450 // cleanupComplete() is running, since some of the regions we find to be 451 // empty might not yet be added to the free list. It is not straightforward 452 // to know in which list they are on so that we can remove them. We only 453 // need to do this if we need to allocate more than one region to satisfy the 454 // current humongous allocation request. If we are only allocating one region 455 // we use the one-region region allocation code (see above), that already 456 // potentially waits for regions from the secondary free list. 457 wait_while_free_regions_coming(); 458 append_secondary_free_list_if_not_empty_with_lock(); 459 460 // Policy: Try only empty regions (i.e. already committed first). Maybe we 461 // are lucky enough to find some. 462 first = _hrm.find_contiguous_only_empty(obj_regions); 463 if (first != G1_NO_HRM_INDEX) { 464 _hrm.allocate_free_regions_starting_at(first, obj_regions); 465 } 466 } 467 468 if (first == G1_NO_HRM_INDEX) { 469 // Policy: We could not find enough regions for the humongous object in the 470 // free list. Look through the heap to find a mix of free and uncommitted regions. 471 // If so, try expansion. 472 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 473 if (first != G1_NO_HRM_INDEX) { 474 // We found something. Make sure these regions are committed, i.e. expand 475 // the heap. Alternatively we could do a defragmentation GC. 476 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", 477 word_size * HeapWordSize); 478 479 480 _hrm.expand_at(first, obj_regions); 481 g1_policy()->record_new_heap_size(num_regions()); 482 483 #ifdef ASSERT 484 for (uint i = first; i < first + obj_regions; ++i) { 485 HeapRegion* hr = region_at(i); 486 assert(hr->is_free(), "sanity"); 487 assert(hr->is_empty(), "sanity"); 488 assert(is_on_master_free_list(hr), "sanity"); 489 } 490 #endif 491 _hrm.allocate_free_regions_starting_at(first, obj_regions); 492 } else { 493 // Policy: Potentially trigger a defragmentation GC. 494 } 495 } 496 497 HeapWord* result = NULL; 498 if (first != G1_NO_HRM_INDEX) { 499 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 500 word_size, context); 501 assert(result != NULL, "it should always return a valid result"); 502 503 // A successful humongous object allocation changes the used space 504 // information of the old generation so we need to recalculate the 505 // sizes and update the jstat counters here. 506 g1mm()->update_sizes(); 507 } 508 509 _verifier->verify_region_sets_optional(); 510 511 return result; 512 } 513 514 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 515 assert_heap_not_locked_and_not_at_safepoint(); 516 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 517 518 uint dummy_gc_count_before; 519 uint dummy_gclocker_retry_count = 0; 520 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 521 } 522 523 HeapWord* 524 G1CollectedHeap::mem_allocate(size_t word_size, 525 bool* gc_overhead_limit_was_exceeded) { 526 assert_heap_not_locked_and_not_at_safepoint(); 527 528 // Loop until the allocation is satisfied, or unsatisfied after GC. 529 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 530 uint gc_count_before; 531 532 HeapWord* result = NULL; 533 if (!is_humongous(word_size)) { 534 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 535 } else { 536 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 537 } 538 if (result != NULL) { 539 return result; 540 } 541 542 // Create the garbage collection operation... 543 VM_G1CollectForAllocation op(gc_count_before, word_size); 544 op.set_allocation_context(AllocationContext::current()); 545 546 // ...and get the VM thread to execute it. 547 VMThread::execute(&op); 548 549 if (op.prologue_succeeded() && op.pause_succeeded()) { 550 // If the operation was successful we'll return the result even 551 // if it is NULL. If the allocation attempt failed immediately 552 // after a Full GC, it's unlikely we'll be able to allocate now. 553 HeapWord* result = op.result(); 554 if (result != NULL && !is_humongous(word_size)) { 555 // Allocations that take place on VM operations do not do any 556 // card dirtying and we have to do it here. We only have to do 557 // this for non-humongous allocations, though. 558 dirty_young_block(result, word_size); 559 } 560 return result; 561 } else { 562 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 563 return NULL; 564 } 565 assert(op.result() == NULL, 566 "the result should be NULL if the VM op did not succeed"); 567 } 568 569 // Give a warning if we seem to be looping forever. 570 if ((QueuedAllocationWarningCount > 0) && 571 (try_count % QueuedAllocationWarningCount == 0)) { 572 log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count); 573 } 574 } 575 576 ShouldNotReachHere(); 577 return NULL; 578 } 579 580 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 581 AllocationContext_t context, 582 uint* gc_count_before_ret, 583 uint* gclocker_retry_count_ret) { 584 // Make sure you read the note in attempt_allocation_humongous(). 585 586 assert_heap_not_locked_and_not_at_safepoint(); 587 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 588 "be called for humongous allocation requests"); 589 590 // We should only get here after the first-level allocation attempt 591 // (attempt_allocation()) failed to allocate. 592 593 // We will loop until a) we manage to successfully perform the 594 // allocation or b) we successfully schedule a collection which 595 // fails to perform the allocation. b) is the only case when we'll 596 // return NULL. 597 HeapWord* result = NULL; 598 for (int try_count = 1; /* we'll return */; try_count += 1) { 599 bool should_try_gc; 600 uint gc_count_before; 601 602 { 603 MutexLockerEx x(Heap_lock); 604 result = _allocator->attempt_allocation_locked(word_size, context); 605 if (result != NULL) { 606 return result; 607 } 608 609 if (GCLocker::is_active_and_needs_gc()) { 610 if (g1_policy()->can_expand_young_list()) { 611 // No need for an ergo verbose message here, 612 // can_expand_young_list() does this when it returns true. 613 result = _allocator->attempt_allocation_force(word_size, context); 614 if (result != NULL) { 615 return result; 616 } 617 } 618 should_try_gc = false; 619 } else { 620 // The GCLocker may not be active but the GCLocker initiated 621 // GC may not yet have been performed (GCLocker::needs_gc() 622 // returns true). In this case we do not try this GC and 623 // wait until the GCLocker initiated GC is performed, and 624 // then retry the allocation. 625 if (GCLocker::needs_gc()) { 626 should_try_gc = false; 627 } else { 628 // Read the GC count while still holding the Heap_lock. 629 gc_count_before = total_collections(); 630 should_try_gc = true; 631 } 632 } 633 } 634 635 if (should_try_gc) { 636 bool succeeded; 637 result = do_collection_pause(word_size, gc_count_before, &succeeded, 638 GCCause::_g1_inc_collection_pause); 639 if (result != NULL) { 640 assert(succeeded, "only way to get back a non-NULL result"); 641 return result; 642 } 643 644 if (succeeded) { 645 // If we get here we successfully scheduled a collection which 646 // failed to allocate. No point in trying to allocate 647 // further. We'll just return NULL. 648 MutexLockerEx x(Heap_lock); 649 *gc_count_before_ret = total_collections(); 650 return NULL; 651 } 652 } else { 653 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 654 MutexLockerEx x(Heap_lock); 655 *gc_count_before_ret = total_collections(); 656 return NULL; 657 } 658 // The GCLocker is either active or the GCLocker initiated 659 // GC has not yet been performed. Stall until it is and 660 // then retry the allocation. 661 GCLocker::stall_until_clear(); 662 (*gclocker_retry_count_ret) += 1; 663 } 664 665 // We can reach here if we were unsuccessful in scheduling a 666 // collection (because another thread beat us to it) or if we were 667 // stalled due to the GC locker. In either can we should retry the 668 // allocation attempt in case another thread successfully 669 // performed a collection and reclaimed enough space. We do the 670 // first attempt (without holding the Heap_lock) here and the 671 // follow-on attempt will be at the start of the next loop 672 // iteration (after taking the Heap_lock). 673 result = _allocator->attempt_allocation(word_size, context); 674 if (result != NULL) { 675 return result; 676 } 677 678 // Give a warning if we seem to be looping forever. 679 if ((QueuedAllocationWarningCount > 0) && 680 (try_count % QueuedAllocationWarningCount == 0)) { 681 log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() " 682 "retries %d times", try_count); 683 } 684 } 685 686 ShouldNotReachHere(); 687 return NULL; 688 } 689 690 void G1CollectedHeap::begin_archive_alloc_range() { 691 assert_at_safepoint(true /* should_be_vm_thread */); 692 if (_archive_allocator == NULL) { 693 _archive_allocator = G1ArchiveAllocator::create_allocator(this); 694 } 695 } 696 697 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 698 // Allocations in archive regions cannot be of a size that would be considered 699 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 700 // may be different at archive-restore time. 701 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 702 } 703 704 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 705 assert_at_safepoint(true /* should_be_vm_thread */); 706 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 707 if (is_archive_alloc_too_large(word_size)) { 708 return NULL; 709 } 710 return _archive_allocator->archive_mem_allocate(word_size); 711 } 712 713 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 714 size_t end_alignment_in_bytes) { 715 assert_at_safepoint(true /* should_be_vm_thread */); 716 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 717 718 // Call complete_archive to do the real work, filling in the MemRegion 719 // array with the archive regions. 720 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 721 delete _archive_allocator; 722 _archive_allocator = NULL; 723 } 724 725 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 726 assert(ranges != NULL, "MemRegion array NULL"); 727 assert(count != 0, "No MemRegions provided"); 728 MemRegion reserved = _hrm.reserved(); 729 for (size_t i = 0; i < count; i++) { 730 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 731 return false; 732 } 733 } 734 return true; 735 } 736 737 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) { 738 assert(!is_init_completed(), "Expect to be called at JVM init time"); 739 assert(ranges != NULL, "MemRegion array NULL"); 740 assert(count != 0, "No MemRegions provided"); 741 MutexLockerEx x(Heap_lock); 742 743 MemRegion reserved = _hrm.reserved(); 744 HeapWord* prev_last_addr = NULL; 745 HeapRegion* prev_last_region = NULL; 746 747 // Temporarily disable pretouching of heap pages. This interface is used 748 // when mmap'ing archived heap data in, so pre-touching is wasted. 749 FlagSetting fs(AlwaysPreTouch, false); 750 751 // Enable archive object checking in G1MarkSweep. We have to let it know 752 // about each archive range, so that objects in those ranges aren't marked. 753 G1MarkSweep::enable_archive_object_check(); 754 755 // For each specified MemRegion range, allocate the corresponding G1 756 // regions and mark them as archive regions. We expect the ranges in 757 // ascending starting address order, without overlap. 758 for (size_t i = 0; i < count; i++) { 759 MemRegion curr_range = ranges[i]; 760 HeapWord* start_address = curr_range.start(); 761 size_t word_size = curr_range.word_size(); 762 HeapWord* last_address = curr_range.last(); 763 size_t commits = 0; 764 765 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 766 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 767 p2i(start_address), p2i(last_address)); 768 guarantee(start_address > prev_last_addr, 769 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 770 p2i(start_address), p2i(prev_last_addr)); 771 prev_last_addr = last_address; 772 773 // Check for ranges that start in the same G1 region in which the previous 774 // range ended, and adjust the start address so we don't try to allocate 775 // the same region again. If the current range is entirely within that 776 // region, skip it, just adjusting the recorded top. 777 HeapRegion* start_region = _hrm.addr_to_region(start_address); 778 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 779 start_address = start_region->end(); 780 if (start_address > last_address) { 781 increase_used(word_size * HeapWordSize); 782 start_region->set_top(last_address + 1); 783 continue; 784 } 785 start_region->set_top(start_address); 786 curr_range = MemRegion(start_address, last_address + 1); 787 start_region = _hrm.addr_to_region(start_address); 788 } 789 790 // Perform the actual region allocation, exiting if it fails. 791 // Then note how much new space we have allocated. 792 if (!_hrm.allocate_containing_regions(curr_range, &commits)) { 793 return false; 794 } 795 increase_used(word_size * HeapWordSize); 796 if (commits != 0) { 797 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 798 HeapRegion::GrainWords * HeapWordSize * commits); 799 800 } 801 802 // Mark each G1 region touched by the range as archive, add it to the old set, 803 // and set the allocation context and top. 804 HeapRegion* curr_region = _hrm.addr_to_region(start_address); 805 HeapRegion* last_region = _hrm.addr_to_region(last_address); 806 prev_last_region = last_region; 807 808 while (curr_region != NULL) { 809 assert(curr_region->is_empty() && !curr_region->is_pinned(), 810 "Region already in use (index %u)", curr_region->hrm_index()); 811 curr_region->set_allocation_context(AllocationContext::system()); 812 curr_region->set_archive(); 813 _hr_printer.alloc(curr_region); 814 _old_set.add(curr_region); 815 if (curr_region != last_region) { 816 curr_region->set_top(curr_region->end()); 817 curr_region = _hrm.next_region_in_heap(curr_region); 818 } else { 819 curr_region->set_top(last_address + 1); 820 curr_region = NULL; 821 } 822 } 823 824 // Notify mark-sweep of the archive range. 825 G1MarkSweep::set_range_archive(curr_range, true); 826 } 827 return true; 828 } 829 830 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 831 assert(!is_init_completed(), "Expect to be called at JVM init time"); 832 assert(ranges != NULL, "MemRegion array NULL"); 833 assert(count != 0, "No MemRegions provided"); 834 MemRegion reserved = _hrm.reserved(); 835 HeapWord *prev_last_addr = NULL; 836 HeapRegion* prev_last_region = NULL; 837 838 // For each MemRegion, create filler objects, if needed, in the G1 regions 839 // that contain the address range. The address range actually within the 840 // MemRegion will not be modified. That is assumed to have been initialized 841 // elsewhere, probably via an mmap of archived heap data. 842 MutexLockerEx x(Heap_lock); 843 for (size_t i = 0; i < count; i++) { 844 HeapWord* start_address = ranges[i].start(); 845 HeapWord* last_address = ranges[i].last(); 846 847 assert(reserved.contains(start_address) && reserved.contains(last_address), 848 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 849 p2i(start_address), p2i(last_address)); 850 assert(start_address > prev_last_addr, 851 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 852 p2i(start_address), p2i(prev_last_addr)); 853 854 HeapRegion* start_region = _hrm.addr_to_region(start_address); 855 HeapRegion* last_region = _hrm.addr_to_region(last_address); 856 HeapWord* bottom_address = start_region->bottom(); 857 858 // Check for a range beginning in the same region in which the 859 // previous one ended. 860 if (start_region == prev_last_region) { 861 bottom_address = prev_last_addr + 1; 862 } 863 864 // Verify that the regions were all marked as archive regions by 865 // alloc_archive_regions. 866 HeapRegion* curr_region = start_region; 867 while (curr_region != NULL) { 868 guarantee(curr_region->is_archive(), 869 "Expected archive region at index %u", curr_region->hrm_index()); 870 if (curr_region != last_region) { 871 curr_region = _hrm.next_region_in_heap(curr_region); 872 } else { 873 curr_region = NULL; 874 } 875 } 876 877 prev_last_addr = last_address; 878 prev_last_region = last_region; 879 880 // Fill the memory below the allocated range with dummy object(s), 881 // if the region bottom does not match the range start, or if the previous 882 // range ended within the same G1 region, and there is a gap. 883 if (start_address != bottom_address) { 884 size_t fill_size = pointer_delta(start_address, bottom_address); 885 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 886 increase_used(fill_size * HeapWordSize); 887 } 888 } 889 } 890 891 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size, 892 uint* gc_count_before_ret, 893 uint* gclocker_retry_count_ret) { 894 assert_heap_not_locked_and_not_at_safepoint(); 895 assert(!is_humongous(word_size), "attempt_allocation() should not " 896 "be called for humongous allocation requests"); 897 898 AllocationContext_t context = AllocationContext::current(); 899 HeapWord* result = _allocator->attempt_allocation(word_size, context); 900 901 if (result == NULL) { 902 result = attempt_allocation_slow(word_size, 903 context, 904 gc_count_before_ret, 905 gclocker_retry_count_ret); 906 } 907 assert_heap_not_locked(); 908 if (result != NULL) { 909 dirty_young_block(result, word_size); 910 } 911 return result; 912 } 913 914 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 915 assert(!is_init_completed(), "Expect to be called at JVM init time"); 916 assert(ranges != NULL, "MemRegion array NULL"); 917 assert(count != 0, "No MemRegions provided"); 918 MemRegion reserved = _hrm.reserved(); 919 HeapWord* prev_last_addr = NULL; 920 HeapRegion* prev_last_region = NULL; 921 size_t size_used = 0; 922 size_t uncommitted_regions = 0; 923 924 // For each Memregion, free the G1 regions that constitute it, and 925 // notify mark-sweep that the range is no longer to be considered 'archive.' 926 MutexLockerEx x(Heap_lock); 927 for (size_t i = 0; i < count; i++) { 928 HeapWord* start_address = ranges[i].start(); 929 HeapWord* last_address = ranges[i].last(); 930 931 assert(reserved.contains(start_address) && reserved.contains(last_address), 932 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 933 p2i(start_address), p2i(last_address)); 934 assert(start_address > prev_last_addr, 935 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 936 p2i(start_address), p2i(prev_last_addr)); 937 size_used += ranges[i].byte_size(); 938 prev_last_addr = last_address; 939 940 HeapRegion* start_region = _hrm.addr_to_region(start_address); 941 HeapRegion* last_region = _hrm.addr_to_region(last_address); 942 943 // Check for ranges that start in the same G1 region in which the previous 944 // range ended, and adjust the start address so we don't try to free 945 // the same region again. If the current range is entirely within that 946 // region, skip it. 947 if (start_region == prev_last_region) { 948 start_address = start_region->end(); 949 if (start_address > last_address) { 950 continue; 951 } 952 start_region = _hrm.addr_to_region(start_address); 953 } 954 prev_last_region = last_region; 955 956 // After verifying that each region was marked as an archive region by 957 // alloc_archive_regions, set it free and empty and uncommit it. 958 HeapRegion* curr_region = start_region; 959 while (curr_region != NULL) { 960 guarantee(curr_region->is_archive(), 961 "Expected archive region at index %u", curr_region->hrm_index()); 962 uint curr_index = curr_region->hrm_index(); 963 _old_set.remove(curr_region); 964 curr_region->set_free(); 965 curr_region->set_top(curr_region->bottom()); 966 if (curr_region != last_region) { 967 curr_region = _hrm.next_region_in_heap(curr_region); 968 } else { 969 curr_region = NULL; 970 } 971 _hrm.shrink_at(curr_index, 1); 972 uncommitted_regions++; 973 } 974 975 // Notify mark-sweep that this is no longer an archive range. 976 G1MarkSweep::set_range_archive(ranges[i], false); 977 } 978 979 if (uncommitted_regions != 0) { 980 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 981 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 982 } 983 decrease_used(size_used); 984 } 985 986 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 987 uint* gc_count_before_ret, 988 uint* gclocker_retry_count_ret) { 989 // The structure of this method has a lot of similarities to 990 // attempt_allocation_slow(). The reason these two were not merged 991 // into a single one is that such a method would require several "if 992 // allocation is not humongous do this, otherwise do that" 993 // conditional paths which would obscure its flow. In fact, an early 994 // version of this code did use a unified method which was harder to 995 // follow and, as a result, it had subtle bugs that were hard to 996 // track down. So keeping these two methods separate allows each to 997 // be more readable. It will be good to keep these two in sync as 998 // much as possible. 999 1000 assert_heap_not_locked_and_not_at_safepoint(); 1001 assert(is_humongous(word_size), "attempt_allocation_humongous() " 1002 "should only be called for humongous allocations"); 1003 1004 // Humongous objects can exhaust the heap quickly, so we should check if we 1005 // need to start a marking cycle at each humongous object allocation. We do 1006 // the check before we do the actual allocation. The reason for doing it 1007 // before the allocation is that we avoid having to keep track of the newly 1008 // allocated memory while we do a GC. 1009 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1010 word_size)) { 1011 collect(GCCause::_g1_humongous_allocation); 1012 } 1013 1014 // We will loop until a) we manage to successfully perform the 1015 // allocation or b) we successfully schedule a collection which 1016 // fails to perform the allocation. b) is the only case when we'll 1017 // return NULL. 1018 HeapWord* result = NULL; 1019 for (int try_count = 1; /* we'll return */; try_count += 1) { 1020 bool should_try_gc; 1021 uint gc_count_before; 1022 1023 { 1024 MutexLockerEx x(Heap_lock); 1025 1026 // Given that humongous objects are not allocated in young 1027 // regions, we'll first try to do the allocation without doing a 1028 // collection hoping that there's enough space in the heap. 1029 result = humongous_obj_allocate(word_size, AllocationContext::current()); 1030 if (result != NULL) { 1031 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 1032 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 1033 return result; 1034 } 1035 1036 if (GCLocker::is_active_and_needs_gc()) { 1037 should_try_gc = false; 1038 } else { 1039 // The GCLocker may not be active but the GCLocker initiated 1040 // GC may not yet have been performed (GCLocker::needs_gc() 1041 // returns true). In this case we do not try this GC and 1042 // wait until the GCLocker initiated GC is performed, and 1043 // then retry the allocation. 1044 if (GCLocker::needs_gc()) { 1045 should_try_gc = false; 1046 } else { 1047 // Read the GC count while still holding the Heap_lock. 1048 gc_count_before = total_collections(); 1049 should_try_gc = true; 1050 } 1051 } 1052 } 1053 1054 if (should_try_gc) { 1055 // If we failed to allocate the humongous object, we should try to 1056 // do a collection pause (if we're allowed) in case it reclaims 1057 // enough space for the allocation to succeed after the pause. 1058 1059 bool succeeded; 1060 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1061 GCCause::_g1_humongous_allocation); 1062 if (result != NULL) { 1063 assert(succeeded, "only way to get back a non-NULL result"); 1064 return result; 1065 } 1066 1067 if (succeeded) { 1068 // If we get here we successfully scheduled a collection which 1069 // failed to allocate. No point in trying to allocate 1070 // further. We'll just return NULL. 1071 MutexLockerEx x(Heap_lock); 1072 *gc_count_before_ret = total_collections(); 1073 return NULL; 1074 } 1075 } else { 1076 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1077 MutexLockerEx x(Heap_lock); 1078 *gc_count_before_ret = total_collections(); 1079 return NULL; 1080 } 1081 // The GCLocker is either active or the GCLocker initiated 1082 // GC has not yet been performed. Stall until it is and 1083 // then retry the allocation. 1084 GCLocker::stall_until_clear(); 1085 (*gclocker_retry_count_ret) += 1; 1086 } 1087 1088 // We can reach here if we were unsuccessful in scheduling a 1089 // collection (because another thread beat us to it) or if we were 1090 // stalled due to the GC locker. In either can we should retry the 1091 // allocation attempt in case another thread successfully 1092 // performed a collection and reclaimed enough space. Give a 1093 // warning if we seem to be looping forever. 1094 1095 if ((QueuedAllocationWarningCount > 0) && 1096 (try_count % QueuedAllocationWarningCount == 0)) { 1097 log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() " 1098 "retries %d times", try_count); 1099 } 1100 } 1101 1102 ShouldNotReachHere(); 1103 return NULL; 1104 } 1105 1106 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1107 AllocationContext_t context, 1108 bool expect_null_mutator_alloc_region) { 1109 assert_at_safepoint(true /* should_be_vm_thread */); 1110 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region, 1111 "the current alloc region was unexpectedly found to be non-NULL"); 1112 1113 if (!is_humongous(word_size)) { 1114 return _allocator->attempt_allocation_locked(word_size, context); 1115 } else { 1116 HeapWord* result = humongous_obj_allocate(word_size, context); 1117 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1118 collector_state()->set_initiate_conc_mark_if_possible(true); 1119 } 1120 return result; 1121 } 1122 1123 ShouldNotReachHere(); 1124 } 1125 1126 class PostMCRemSetClearClosure: public HeapRegionClosure { 1127 G1CollectedHeap* _g1h; 1128 ModRefBarrierSet* _mr_bs; 1129 public: 1130 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1131 _g1h(g1h), _mr_bs(mr_bs) {} 1132 1133 bool doHeapRegion(HeapRegion* r) { 1134 HeapRegionRemSet* hrrs = r->rem_set(); 1135 1136 _g1h->reset_gc_time_stamps(r); 1137 1138 if (r->is_continues_humongous()) { 1139 // We'll assert that the strong code root list and RSet is empty 1140 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1141 assert(hrrs->occupied() == 0, "RSet should be empty"); 1142 } else { 1143 hrrs->clear(); 1144 } 1145 // You might think here that we could clear just the cards 1146 // corresponding to the used region. But no: if we leave a dirty card 1147 // in a region we might allocate into, then it would prevent that card 1148 // from being enqueued, and cause it to be missed. 1149 // Re: the performance cost: we shouldn't be doing full GC anyway! 1150 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1151 1152 return false; 1153 } 1154 }; 1155 1156 void G1CollectedHeap::clear_rsets_post_compaction() { 1157 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1158 heap_region_iterate(&rs_clear); 1159 } 1160 1161 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1162 G1CollectedHeap* _g1h; 1163 UpdateRSOopClosure _cl; 1164 public: 1165 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) : 1166 _cl(g1->g1_rem_set(), worker_i), 1167 _g1h(g1) 1168 { } 1169 1170 bool doHeapRegion(HeapRegion* r) { 1171 if (!r->is_continues_humongous()) { 1172 _cl.set_from(r); 1173 r->oop_iterate(&_cl); 1174 } 1175 return false; 1176 } 1177 }; 1178 1179 class ParRebuildRSTask: public AbstractGangTask { 1180 G1CollectedHeap* _g1; 1181 HeapRegionClaimer _hrclaimer; 1182 1183 public: 1184 ParRebuildRSTask(G1CollectedHeap* g1) : 1185 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {} 1186 1187 void work(uint worker_id) { 1188 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1189 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer); 1190 } 1191 }; 1192 1193 class PostCompactionPrinterClosure: public HeapRegionClosure { 1194 private: 1195 G1HRPrinter* _hr_printer; 1196 public: 1197 bool doHeapRegion(HeapRegion* hr) { 1198 assert(!hr->is_young(), "not expecting to find young regions"); 1199 _hr_printer->post_compaction(hr); 1200 return false; 1201 } 1202 1203 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1204 : _hr_printer(hr_printer) { } 1205 }; 1206 1207 void G1CollectedHeap::print_hrm_post_compaction() { 1208 if (_hr_printer.is_active()) { 1209 PostCompactionPrinterClosure cl(hr_printer()); 1210 heap_region_iterate(&cl); 1211 } 1212 1213 } 1214 1215 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1216 bool clear_all_soft_refs) { 1217 assert_at_safepoint(true /* should_be_vm_thread */); 1218 1219 if (GCLocker::check_active_before_gc()) { 1220 return false; 1221 } 1222 1223 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1224 gc_timer->register_gc_start(); 1225 1226 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1227 GCIdMark gc_id_mark; 1228 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1229 1230 SvcGCMarker sgcm(SvcGCMarker::FULL); 1231 ResourceMark rm; 1232 1233 print_heap_before_gc(); 1234 print_heap_regions(); 1235 trace_heap_before_gc(gc_tracer); 1236 1237 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1238 1239 _verifier->verify_region_sets_optional(); 1240 1241 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1242 collector_policy()->should_clear_all_soft_refs(); 1243 1244 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1245 1246 { 1247 IsGCActiveMark x; 1248 1249 // Timing 1250 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1251 GCTraceCPUTime tcpu; 1252 1253 { 1254 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1255 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1256 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1257 1258 G1HeapTransition heap_transition(this); 1259 g1_policy()->record_full_collection_start(); 1260 1261 // Note: When we have a more flexible GC logging framework that 1262 // allows us to add optional attributes to a GC log record we 1263 // could consider timing and reporting how long we wait in the 1264 // following two methods. 1265 wait_while_free_regions_coming(); 1266 // If we start the compaction before the CM threads finish 1267 // scanning the root regions we might trip them over as we'll 1268 // be moving objects / updating references. So let's wait until 1269 // they are done. By telling them to abort, they should complete 1270 // early. 1271 _cm->root_regions()->abort(); 1272 _cm->root_regions()->wait_until_scan_finished(); 1273 append_secondary_free_list_if_not_empty_with_lock(); 1274 1275 gc_prologue(true); 1276 increment_total_collections(true /* full gc */); 1277 increment_old_marking_cycles_started(); 1278 1279 assert(used() == recalculate_used(), "Should be equal"); 1280 1281 _verifier->verify_before_gc(); 1282 1283 _verifier->check_bitmaps("Full GC Start"); 1284 pre_full_gc_dump(gc_timer); 1285 1286 #if defined(COMPILER2) || INCLUDE_JVMCI 1287 DerivedPointerTable::clear(); 1288 #endif 1289 1290 // Disable discovery and empty the discovered lists 1291 // for the CM ref processor. 1292 ref_processor_cm()->disable_discovery(); 1293 ref_processor_cm()->abandon_partial_discovery(); 1294 ref_processor_cm()->verify_no_references_recorded(); 1295 1296 // Abandon current iterations of concurrent marking and concurrent 1297 // refinement, if any are in progress. 1298 concurrent_mark()->abort(); 1299 1300 // Make sure we'll choose a new allocation region afterwards. 1301 _allocator->release_mutator_alloc_region(); 1302 _allocator->abandon_gc_alloc_regions(); 1303 g1_rem_set()->cleanupHRRS(); 1304 1305 // We may have added regions to the current incremental collection 1306 // set between the last GC or pause and now. We need to clear the 1307 // incremental collection set and then start rebuilding it afresh 1308 // after this full GC. 1309 abandon_collection_set(collection_set()->inc_head()); 1310 collection_set()->clear_incremental(); 1311 collection_set()->stop_incremental_building(); 1312 1313 tear_down_region_sets(false /* free_list_only */); 1314 collector_state()->set_gcs_are_young(true); 1315 1316 // See the comments in g1CollectedHeap.hpp and 1317 // G1CollectedHeap::ref_processing_init() about 1318 // how reference processing currently works in G1. 1319 1320 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1321 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1322 1323 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1324 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1325 1326 ref_processor_stw()->enable_discovery(); 1327 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1328 1329 // Do collection work 1330 { 1331 HandleMark hm; // Discard invalid handles created during gc 1332 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1333 } 1334 1335 assert(num_free_regions() == 0, "we should not have added any free regions"); 1336 rebuild_region_sets(false /* free_list_only */); 1337 1338 // Enqueue any discovered reference objects that have 1339 // not been removed from the discovered lists. 1340 ref_processor_stw()->enqueue_discovered_references(); 1341 1342 #if defined(COMPILER2) || INCLUDE_JVMCI 1343 DerivedPointerTable::update_pointers(); 1344 #endif 1345 1346 MemoryService::track_memory_usage(); 1347 1348 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1349 ref_processor_stw()->verify_no_references_recorded(); 1350 1351 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1352 ClassLoaderDataGraph::purge(); 1353 MetaspaceAux::verify_metrics(); 1354 1355 // Note: since we've just done a full GC, concurrent 1356 // marking is no longer active. Therefore we need not 1357 // re-enable reference discovery for the CM ref processor. 1358 // That will be done at the start of the next marking cycle. 1359 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1360 ref_processor_cm()->verify_no_references_recorded(); 1361 1362 reset_gc_time_stamp(); 1363 // Since everything potentially moved, we will clear all remembered 1364 // sets, and clear all cards. Later we will rebuild remembered 1365 // sets. We will also reset the GC time stamps of the regions. 1366 clear_rsets_post_compaction(); 1367 check_gc_time_stamps(); 1368 1369 resize_if_necessary_after_full_collection(); 1370 1371 // We should do this after we potentially resize the heap so 1372 // that all the COMMIT / UNCOMMIT events are generated before 1373 // the compaction events. 1374 print_hrm_post_compaction(); 1375 1376 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1377 if (hot_card_cache->use_cache()) { 1378 hot_card_cache->reset_card_counts(); 1379 hot_card_cache->reset_hot_cache(); 1380 } 1381 1382 // Rebuild remembered sets of all regions. 1383 uint n_workers = 1384 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1385 workers()->active_workers(), 1386 Threads::number_of_non_daemon_threads()); 1387 workers()->set_active_workers(n_workers); 1388 1389 ParRebuildRSTask rebuild_rs_task(this); 1390 workers()->run_task(&rebuild_rs_task); 1391 1392 // Rebuild the strong code root lists for each region 1393 rebuild_strong_code_roots(); 1394 1395 if (true) { // FIXME 1396 MetaspaceGC::compute_new_size(); 1397 } 1398 1399 #ifdef TRACESPINNING 1400 ParallelTaskTerminator::print_termination_counts(); 1401 #endif 1402 1403 // Discard all rset updates 1404 JavaThread::dirty_card_queue_set().abandon_logs(); 1405 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1406 1407 // At this point there should be no regions in the 1408 // entire heap tagged as young. 1409 assert(check_young_list_empty(true /* check_heap */), 1410 "young list should be empty at this point"); 1411 1412 // Update the number of full collections that have been completed. 1413 increment_old_marking_cycles_completed(false /* concurrent */); 1414 1415 _hrm.verify_optional(); 1416 _verifier->verify_region_sets_optional(); 1417 1418 _verifier->verify_after_gc(); 1419 1420 // Clear the previous marking bitmap, if needed for bitmap verification. 1421 // Note we cannot do this when we clear the next marking bitmap in 1422 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1423 // objects marked during a full GC against the previous bitmap. 1424 // But we need to clear it before calling check_bitmaps below since 1425 // the full GC has compacted objects and updated TAMS but not updated 1426 // the prev bitmap. 1427 if (G1VerifyBitmaps) { 1428 _cm->clear_prev_bitmap(workers()); 1429 } 1430 _verifier->check_bitmaps("Full GC End"); 1431 1432 // Start a new incremental collection set for the next pause 1433 assert(collection_set()->head() == NULL, "must be"); 1434 collection_set()->start_incremental_building(); 1435 1436 clear_cset_fast_test(); 1437 1438 _allocator->init_mutator_alloc_region(); 1439 1440 g1_policy()->record_full_collection_end(); 1441 1442 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1443 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1444 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1445 // before any GC notifications are raised. 1446 g1mm()->update_sizes(); 1447 1448 gc_epilogue(true); 1449 1450 heap_transition.print(); 1451 1452 print_heap_after_gc(); 1453 print_heap_regions(); 1454 trace_heap_after_gc(gc_tracer); 1455 1456 post_full_gc_dump(gc_timer); 1457 } 1458 1459 gc_timer->register_gc_end(); 1460 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1461 } 1462 1463 return true; 1464 } 1465 1466 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1467 // Currently, there is no facility in the do_full_collection(bool) API to notify 1468 // the caller that the collection did not succeed (e.g., because it was locked 1469 // out by the GC locker). So, right now, we'll ignore the return value. 1470 bool dummy = do_full_collection(true, /* explicit_gc */ 1471 clear_all_soft_refs); 1472 } 1473 1474 void G1CollectedHeap::resize_if_necessary_after_full_collection() { 1475 // Include bytes that will be pre-allocated to support collections, as "used". 1476 const size_t used_after_gc = used(); 1477 const size_t capacity_after_gc = capacity(); 1478 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1479 1480 // This is enforced in arguments.cpp. 1481 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1482 "otherwise the code below doesn't make sense"); 1483 1484 // We don't have floating point command-line arguments 1485 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1486 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1487 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1488 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1489 1490 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1491 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1492 1493 // We have to be careful here as these two calculations can overflow 1494 // 32-bit size_t's. 1495 double used_after_gc_d = (double) used_after_gc; 1496 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1497 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1498 1499 // Let's make sure that they are both under the max heap size, which 1500 // by default will make them fit into a size_t. 1501 double desired_capacity_upper_bound = (double) max_heap_size; 1502 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1503 desired_capacity_upper_bound); 1504 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1505 desired_capacity_upper_bound); 1506 1507 // We can now safely turn them into size_t's. 1508 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1509 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1510 1511 // This assert only makes sense here, before we adjust them 1512 // with respect to the min and max heap size. 1513 assert(minimum_desired_capacity <= maximum_desired_capacity, 1514 "minimum_desired_capacity = " SIZE_FORMAT ", " 1515 "maximum_desired_capacity = " SIZE_FORMAT, 1516 minimum_desired_capacity, maximum_desired_capacity); 1517 1518 // Should not be greater than the heap max size. No need to adjust 1519 // it with respect to the heap min size as it's a lower bound (i.e., 1520 // we'll try to make the capacity larger than it, not smaller). 1521 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1522 // Should not be less than the heap min size. No need to adjust it 1523 // with respect to the heap max size as it's an upper bound (i.e., 1524 // we'll try to make the capacity smaller than it, not greater). 1525 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1526 1527 if (capacity_after_gc < minimum_desired_capacity) { 1528 // Don't expand unless it's significant 1529 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1530 1531 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). " 1532 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1533 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio); 1534 1535 expand(expand_bytes); 1536 1537 // No expansion, now see if we want to shrink 1538 } else if (capacity_after_gc > maximum_desired_capacity) { 1539 // Capacity too large, compute shrinking size 1540 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1541 1542 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). " 1543 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1544 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio); 1545 1546 shrink(shrink_bytes); 1547 } 1548 } 1549 1550 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1551 AllocationContext_t context, 1552 bool do_gc, 1553 bool clear_all_soft_refs, 1554 bool expect_null_mutator_alloc_region, 1555 bool* gc_succeeded) { 1556 *gc_succeeded = true; 1557 // Let's attempt the allocation first. 1558 HeapWord* result = 1559 attempt_allocation_at_safepoint(word_size, 1560 context, 1561 expect_null_mutator_alloc_region); 1562 if (result != NULL) { 1563 assert(*gc_succeeded, "sanity"); 1564 return result; 1565 } 1566 1567 // In a G1 heap, we're supposed to keep allocation from failing by 1568 // incremental pauses. Therefore, at least for now, we'll favor 1569 // expansion over collection. (This might change in the future if we can 1570 // do something smarter than full collection to satisfy a failed alloc.) 1571 result = expand_and_allocate(word_size, context); 1572 if (result != NULL) { 1573 assert(*gc_succeeded, "sanity"); 1574 return result; 1575 } 1576 1577 if (do_gc) { 1578 // Expansion didn't work, we'll try to do a Full GC. 1579 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1580 clear_all_soft_refs); 1581 } 1582 1583 return NULL; 1584 } 1585 1586 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1587 AllocationContext_t context, 1588 bool* succeeded) { 1589 assert_at_safepoint(true /* should_be_vm_thread */); 1590 1591 // Attempts to allocate followed by Full GC. 1592 HeapWord* result = 1593 satisfy_failed_allocation_helper(word_size, 1594 context, 1595 true, /* do_gc */ 1596 false, /* clear_all_soft_refs */ 1597 false, /* expect_null_mutator_alloc_region */ 1598 succeeded); 1599 1600 if (result != NULL || !*succeeded) { 1601 return result; 1602 } 1603 1604 // Attempts to allocate followed by Full GC that will collect all soft references. 1605 result = satisfy_failed_allocation_helper(word_size, 1606 context, 1607 true, /* do_gc */ 1608 true, /* clear_all_soft_refs */ 1609 true, /* expect_null_mutator_alloc_region */ 1610 succeeded); 1611 1612 if (result != NULL || !*succeeded) { 1613 return result; 1614 } 1615 1616 // Attempts to allocate, no GC 1617 result = satisfy_failed_allocation_helper(word_size, 1618 context, 1619 false, /* do_gc */ 1620 false, /* clear_all_soft_refs */ 1621 true, /* expect_null_mutator_alloc_region */ 1622 succeeded); 1623 1624 if (result != NULL) { 1625 assert(*succeeded, "sanity"); 1626 return result; 1627 } 1628 1629 assert(!collector_policy()->should_clear_all_soft_refs(), 1630 "Flag should have been handled and cleared prior to this point"); 1631 1632 // What else? We might try synchronous finalization later. If the total 1633 // space available is large enough for the allocation, then a more 1634 // complete compaction phase than we've tried so far might be 1635 // appropriate. 1636 assert(*succeeded, "sanity"); 1637 return NULL; 1638 } 1639 1640 // Attempting to expand the heap sufficiently 1641 // to support an allocation of the given "word_size". If 1642 // successful, perform the allocation and return the address of the 1643 // allocated block, or else "NULL". 1644 1645 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1646 assert_at_safepoint(true /* should_be_vm_thread */); 1647 1648 _verifier->verify_region_sets_optional(); 1649 1650 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1651 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1652 word_size * HeapWordSize); 1653 1654 1655 if (expand(expand_bytes)) { 1656 _hrm.verify_optional(); 1657 _verifier->verify_region_sets_optional(); 1658 return attempt_allocation_at_safepoint(word_size, 1659 context, 1660 false /* expect_null_mutator_alloc_region */); 1661 } 1662 return NULL; 1663 } 1664 1665 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) { 1666 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1667 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1668 HeapRegion::GrainBytes); 1669 1670 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B", 1671 expand_bytes, aligned_expand_bytes); 1672 1673 if (is_maximal_no_gc()) { 1674 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1675 return false; 1676 } 1677 1678 double expand_heap_start_time_sec = os::elapsedTime(); 1679 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1680 assert(regions_to_expand > 0, "Must expand by at least one region"); 1681 1682 uint expanded_by = _hrm.expand_by(regions_to_expand); 1683 if (expand_time_ms != NULL) { 1684 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1685 } 1686 1687 if (expanded_by > 0) { 1688 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1689 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1690 g1_policy()->record_new_heap_size(num_regions()); 1691 } else { 1692 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1693 1694 // The expansion of the virtual storage space was unsuccessful. 1695 // Let's see if it was because we ran out of swap. 1696 if (G1ExitOnExpansionFailure && 1697 _hrm.available() >= regions_to_expand) { 1698 // We had head room... 1699 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1700 } 1701 } 1702 return regions_to_expand > 0; 1703 } 1704 1705 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1706 size_t aligned_shrink_bytes = 1707 ReservedSpace::page_align_size_down(shrink_bytes); 1708 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1709 HeapRegion::GrainBytes); 1710 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1711 1712 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1713 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1714 1715 1716 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", 1717 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1718 if (num_regions_removed > 0) { 1719 g1_policy()->record_new_heap_size(num_regions()); 1720 } else { 1721 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1722 } 1723 } 1724 1725 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1726 _verifier->verify_region_sets_optional(); 1727 1728 // We should only reach here at the end of a Full GC which means we 1729 // should not not be holding to any GC alloc regions. The method 1730 // below will make sure of that and do any remaining clean up. 1731 _allocator->abandon_gc_alloc_regions(); 1732 1733 // Instead of tearing down / rebuilding the free lists here, we 1734 // could instead use the remove_all_pending() method on free_list to 1735 // remove only the ones that we need to remove. 1736 tear_down_region_sets(true /* free_list_only */); 1737 shrink_helper(shrink_bytes); 1738 rebuild_region_sets(true /* free_list_only */); 1739 1740 _hrm.verify_optional(); 1741 _verifier->verify_region_sets_optional(); 1742 } 1743 1744 // Public methods. 1745 1746 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1747 CollectedHeap(), 1748 _g1_policy(policy_), 1749 _collection_set(this), 1750 _dirty_card_queue_set(false), 1751 _is_alive_closure_cm(this), 1752 _is_alive_closure_stw(this), 1753 _ref_processor_cm(NULL), 1754 _ref_processor_stw(NULL), 1755 _bot(NULL), 1756 _cg1r(NULL), 1757 _g1mm(NULL), 1758 _refine_cte_cl(NULL), 1759 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1760 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1761 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1762 _humongous_reclaim_candidates(), 1763 _has_humongous_reclaim_candidates(false), 1764 _archive_allocator(NULL), 1765 _free_regions_coming(false), 1766 _young_list(new YoungList(this)), 1767 _gc_time_stamp(0), 1768 _summary_bytes_used(0), 1769 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1770 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1771 _expand_heap_after_alloc_failure(true), 1772 _old_marking_cycles_started(0), 1773 _old_marking_cycles_completed(0), 1774 _in_cset_fast_test(), 1775 _dirty_cards_region_list(NULL), 1776 _worker_cset_start_region(NULL), 1777 _worker_cset_start_region_time_stamp(NULL), 1778 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1779 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()) { 1780 1781 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1782 /* are_GC_task_threads */true, 1783 /* are_ConcurrentGC_threads */false); 1784 _workers->initialize_workers(); 1785 _verifier = new G1HeapVerifier(this); 1786 1787 _allocator = G1Allocator::create_allocator(this); 1788 1789 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics()); 1790 1791 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1792 1793 // Override the default _filler_array_max_size so that no humongous filler 1794 // objects are created. 1795 _filler_array_max_size = _humongous_object_threshold_in_words; 1796 1797 uint n_queues = ParallelGCThreads; 1798 _task_queues = new RefToScanQueueSet(n_queues); 1799 1800 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1801 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC); 1802 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1803 1804 for (uint i = 0; i < n_queues; i++) { 1805 RefToScanQueue* q = new RefToScanQueue(); 1806 q->initialize(); 1807 _task_queues->register_queue(i, q); 1808 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1809 } 1810 clear_cset_start_regions(); 1811 1812 // Initialize the G1EvacuationFailureALot counters and flags. 1813 NOT_PRODUCT(reset_evacuation_should_fail();) 1814 1815 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1816 } 1817 1818 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1819 size_t size, 1820 size_t translation_factor) { 1821 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1822 // Allocate a new reserved space, preferring to use large pages. 1823 ReservedSpace rs(size, preferred_page_size); 1824 G1RegionToSpaceMapper* result = 1825 G1RegionToSpaceMapper::create_mapper(rs, 1826 size, 1827 rs.alignment(), 1828 HeapRegion::GrainBytes, 1829 translation_factor, 1830 mtGC); 1831 if (TracePageSizes) { 1832 tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT, 1833 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size); 1834 } 1835 return result; 1836 } 1837 1838 jint G1CollectedHeap::initialize() { 1839 CollectedHeap::pre_initialize(); 1840 os::enable_vtime(); 1841 1842 // Necessary to satisfy locking discipline assertions. 1843 1844 MutexLocker x(Heap_lock); 1845 1846 // While there are no constraints in the GC code that HeapWordSize 1847 // be any particular value, there are multiple other areas in the 1848 // system which believe this to be true (e.g. oop->object_size in some 1849 // cases incorrectly returns the size in wordSize units rather than 1850 // HeapWordSize). 1851 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1852 1853 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1854 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1855 size_t heap_alignment = collector_policy()->heap_alignment(); 1856 1857 // Ensure that the sizes are properly aligned. 1858 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1859 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1860 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1861 1862 _refine_cte_cl = new RefineCardTableEntryClosure(); 1863 1864 jint ecode = JNI_OK; 1865 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode); 1866 if (_cg1r == NULL) { 1867 return ecode; 1868 } 1869 1870 // Reserve the maximum. 1871 1872 // When compressed oops are enabled, the preferred heap base 1873 // is calculated by subtracting the requested size from the 1874 // 32Gb boundary and using the result as the base address for 1875 // heap reservation. If the requested size is not aligned to 1876 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1877 // into the ReservedHeapSpace constructor) then the actual 1878 // base of the reserved heap may end up differing from the 1879 // address that was requested (i.e. the preferred heap base). 1880 // If this happens then we could end up using a non-optimal 1881 // compressed oops mode. 1882 1883 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1884 heap_alignment); 1885 1886 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1887 1888 // Create the barrier set for the entire reserved region. 1889 G1SATBCardTableLoggingModRefBS* bs 1890 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 1891 bs->initialize(); 1892 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 1893 set_barrier_set(bs); 1894 1895 // Also create a G1 rem set. 1896 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 1897 1898 // Carve out the G1 part of the heap. 1899 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1900 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 1901 G1RegionToSpaceMapper* heap_storage = 1902 G1RegionToSpaceMapper::create_mapper(g1_rs, 1903 g1_rs.size(), 1904 page_size, 1905 HeapRegion::GrainBytes, 1906 1, 1907 mtJavaHeap); 1908 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(), 1909 max_byte_size, page_size, 1910 heap_rs.base(), 1911 heap_rs.size()); 1912 heap_storage->set_mapping_changed_listener(&_listener); 1913 1914 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1915 G1RegionToSpaceMapper* bot_storage = 1916 create_aux_memory_mapper("Block offset table", 1917 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1918 G1BlockOffsetTable::heap_map_factor()); 1919 1920 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 1921 G1RegionToSpaceMapper* cardtable_storage = 1922 create_aux_memory_mapper("Card table", 1923 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize), 1924 G1SATBCardTableLoggingModRefBS::heap_map_factor()); 1925 1926 G1RegionToSpaceMapper* card_counts_storage = 1927 create_aux_memory_mapper("Card counts table", 1928 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1929 G1CardCounts::heap_map_factor()); 1930 1931 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1932 G1RegionToSpaceMapper* prev_bitmap_storage = 1933 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1934 G1RegionToSpaceMapper* next_bitmap_storage = 1935 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1936 1937 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1938 g1_barrier_set()->initialize(cardtable_storage); 1939 // Do later initialization work for concurrent refinement. 1940 _cg1r->init(card_counts_storage); 1941 1942 // 6843694 - ensure that the maximum region index can fit 1943 // in the remembered set structures. 1944 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1945 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1946 1947 G1RemSet::initialize(max_regions()); 1948 1949 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1950 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1951 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1952 "too many cards per region"); 1953 1954 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1955 1956 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1957 1958 { 1959 HeapWord* start = _hrm.reserved().start(); 1960 HeapWord* end = _hrm.reserved().end(); 1961 size_t granularity = HeapRegion::GrainBytes; 1962 1963 _in_cset_fast_test.initialize(start, end, granularity); 1964 _humongous_reclaim_candidates.initialize(start, end, granularity); 1965 } 1966 1967 // Create the G1ConcurrentMark data structure and thread. 1968 // (Must do this late, so that "max_regions" is defined.) 1969 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1970 if (_cm == NULL || !_cm->completed_initialization()) { 1971 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1972 return JNI_ENOMEM; 1973 } 1974 _cmThread = _cm->cmThread(); 1975 1976 // Now expand into the initial heap size. 1977 if (!expand(init_byte_size)) { 1978 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1979 return JNI_ENOMEM; 1980 } 1981 1982 // Perform any initialization actions delegated to the policy. 1983 g1_policy()->init(); 1984 1985 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 1986 SATB_Q_FL_lock, 1987 G1SATBProcessCompletedThreshold, 1988 Shared_SATB_Q_lock); 1989 1990 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 1991 DirtyCardQ_CBL_mon, 1992 DirtyCardQ_FL_lock, 1993 (int)concurrent_g1_refine()->yellow_zone(), 1994 (int)concurrent_g1_refine()->red_zone(), 1995 Shared_DirtyCardQ_lock, 1996 NULL, // fl_owner 1997 true); // init_free_ids 1998 1999 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 2000 DirtyCardQ_CBL_mon, 2001 DirtyCardQ_FL_lock, 2002 -1, // never trigger processing 2003 -1, // no limit on length 2004 Shared_DirtyCardQ_lock, 2005 &JavaThread::dirty_card_queue_set()); 2006 2007 // Here we allocate the dummy HeapRegion that is required by the 2008 // G1AllocRegion class. 2009 HeapRegion* dummy_region = _hrm.get_dummy_region(); 2010 2011 // We'll re-use the same region whether the alloc region will 2012 // require BOT updates or not and, if it doesn't, then a non-young 2013 // region will complain that it cannot support allocations without 2014 // BOT updates. So we'll tag the dummy region as eden to avoid that. 2015 dummy_region->set_eden(); 2016 // Make sure it's full. 2017 dummy_region->set_top(dummy_region->end()); 2018 G1AllocRegion::setup(this, dummy_region); 2019 2020 _allocator->init_mutator_alloc_region(); 2021 2022 // Do create of the monitoring and management support so that 2023 // values in the heap have been properly initialized. 2024 _g1mm = new G1MonitoringSupport(this); 2025 2026 G1StringDedup::initialize(); 2027 2028 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC); 2029 for (uint i = 0; i < ParallelGCThreads; i++) { 2030 new (&_preserved_objs[i]) OopAndMarkOopStack(); 2031 } 2032 2033 return JNI_OK; 2034 } 2035 2036 void G1CollectedHeap::stop() { 2037 // Stop all concurrent threads. We do this to make sure these threads 2038 // do not continue to execute and access resources (e.g. logging) 2039 // that are destroyed during shutdown. 2040 _cg1r->stop(); 2041 _cmThread->stop(); 2042 if (G1StringDedup::is_enabled()) { 2043 G1StringDedup::stop(); 2044 } 2045 } 2046 2047 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2048 return HeapRegion::max_region_size(); 2049 } 2050 2051 void G1CollectedHeap::post_initialize() { 2052 CollectedHeap::post_initialize(); 2053 ref_processing_init(); 2054 } 2055 2056 void G1CollectedHeap::ref_processing_init() { 2057 // Reference processing in G1 currently works as follows: 2058 // 2059 // * There are two reference processor instances. One is 2060 // used to record and process discovered references 2061 // during concurrent marking; the other is used to 2062 // record and process references during STW pauses 2063 // (both full and incremental). 2064 // * Both ref processors need to 'span' the entire heap as 2065 // the regions in the collection set may be dotted around. 2066 // 2067 // * For the concurrent marking ref processor: 2068 // * Reference discovery is enabled at initial marking. 2069 // * Reference discovery is disabled and the discovered 2070 // references processed etc during remarking. 2071 // * Reference discovery is MT (see below). 2072 // * Reference discovery requires a barrier (see below). 2073 // * Reference processing may or may not be MT 2074 // (depending on the value of ParallelRefProcEnabled 2075 // and ParallelGCThreads). 2076 // * A full GC disables reference discovery by the CM 2077 // ref processor and abandons any entries on it's 2078 // discovered lists. 2079 // 2080 // * For the STW processor: 2081 // * Non MT discovery is enabled at the start of a full GC. 2082 // * Processing and enqueueing during a full GC is non-MT. 2083 // * During a full GC, references are processed after marking. 2084 // 2085 // * Discovery (may or may not be MT) is enabled at the start 2086 // of an incremental evacuation pause. 2087 // * References are processed near the end of a STW evacuation pause. 2088 // * For both types of GC: 2089 // * Discovery is atomic - i.e. not concurrent. 2090 // * Reference discovery will not need a barrier. 2091 2092 MemRegion mr = reserved_region(); 2093 2094 // Concurrent Mark ref processor 2095 _ref_processor_cm = 2096 new ReferenceProcessor(mr, // span 2097 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2098 // mt processing 2099 ParallelGCThreads, 2100 // degree of mt processing 2101 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2102 // mt discovery 2103 MAX2(ParallelGCThreads, ConcGCThreads), 2104 // degree of mt discovery 2105 false, 2106 // Reference discovery is not atomic 2107 &_is_alive_closure_cm); 2108 // is alive closure 2109 // (for efficiency/performance) 2110 2111 // STW ref processor 2112 _ref_processor_stw = 2113 new ReferenceProcessor(mr, // span 2114 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2115 // mt processing 2116 ParallelGCThreads, 2117 // degree of mt processing 2118 (ParallelGCThreads > 1), 2119 // mt discovery 2120 ParallelGCThreads, 2121 // degree of mt discovery 2122 true, 2123 // Reference discovery is atomic 2124 &_is_alive_closure_stw); 2125 // is alive closure 2126 // (for efficiency/performance) 2127 } 2128 2129 CollectorPolicy* G1CollectedHeap::collector_policy() const { 2130 return g1_policy(); 2131 } 2132 2133 size_t G1CollectedHeap::capacity() const { 2134 return _hrm.length() * HeapRegion::GrainBytes; 2135 } 2136 2137 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2138 hr->reset_gc_time_stamp(); 2139 } 2140 2141 #ifndef PRODUCT 2142 2143 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2144 private: 2145 unsigned _gc_time_stamp; 2146 bool _failures; 2147 2148 public: 2149 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2150 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2151 2152 virtual bool doHeapRegion(HeapRegion* hr) { 2153 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2154 if (_gc_time_stamp != region_gc_time_stamp) { 2155 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr), 2156 region_gc_time_stamp, _gc_time_stamp); 2157 _failures = true; 2158 } 2159 return false; 2160 } 2161 2162 bool failures() { return _failures; } 2163 }; 2164 2165 void G1CollectedHeap::check_gc_time_stamps() { 2166 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2167 heap_region_iterate(&cl); 2168 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2169 } 2170 #endif // PRODUCT 2171 2172 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) { 2173 _cg1r->hot_card_cache()->drain(cl, worker_i); 2174 } 2175 2176 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) { 2177 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2178 size_t n_completed_buffers = 0; 2179 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2180 n_completed_buffers++; 2181 } 2182 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 2183 dcqs.clear_n_completed_buffers(); 2184 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2185 } 2186 2187 // Computes the sum of the storage used by the various regions. 2188 size_t G1CollectedHeap::used() const { 2189 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 2190 if (_archive_allocator != NULL) { 2191 result += _archive_allocator->used(); 2192 } 2193 return result; 2194 } 2195 2196 size_t G1CollectedHeap::used_unlocked() const { 2197 return _summary_bytes_used; 2198 } 2199 2200 class SumUsedClosure: public HeapRegionClosure { 2201 size_t _used; 2202 public: 2203 SumUsedClosure() : _used(0) {} 2204 bool doHeapRegion(HeapRegion* r) { 2205 _used += r->used(); 2206 return false; 2207 } 2208 size_t result() { return _used; } 2209 }; 2210 2211 size_t G1CollectedHeap::recalculate_used() const { 2212 double recalculate_used_start = os::elapsedTime(); 2213 2214 SumUsedClosure blk; 2215 heap_region_iterate(&blk); 2216 2217 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2218 return blk.result(); 2219 } 2220 2221 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 2222 switch (cause) { 2223 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2224 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 2225 case GCCause::_update_allocation_context_stats_inc: return true; 2226 case GCCause::_wb_conc_mark: return true; 2227 default : return false; 2228 } 2229 } 2230 2231 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2232 switch (cause) { 2233 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2234 case GCCause::_g1_humongous_allocation: return true; 2235 default: return is_user_requested_concurrent_full_gc(cause); 2236 } 2237 } 2238 2239 #ifndef PRODUCT 2240 void G1CollectedHeap::allocate_dummy_regions() { 2241 // Let's fill up most of the region 2242 size_t word_size = HeapRegion::GrainWords - 1024; 2243 // And as a result the region we'll allocate will be humongous. 2244 guarantee(is_humongous(word_size), "sanity"); 2245 2246 // _filler_array_max_size is set to humongous object threshold 2247 // but temporarily change it to use CollectedHeap::fill_with_object(). 2248 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2249 2250 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2251 // Let's use the existing mechanism for the allocation 2252 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2253 AllocationContext::system()); 2254 if (dummy_obj != NULL) { 2255 MemRegion mr(dummy_obj, word_size); 2256 CollectedHeap::fill_with_object(mr); 2257 } else { 2258 // If we can't allocate once, we probably cannot allocate 2259 // again. Let's get out of the loop. 2260 break; 2261 } 2262 } 2263 } 2264 #endif // !PRODUCT 2265 2266 void G1CollectedHeap::increment_old_marking_cycles_started() { 2267 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2268 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2269 "Wrong marking cycle count (started: %d, completed: %d)", 2270 _old_marking_cycles_started, _old_marking_cycles_completed); 2271 2272 _old_marking_cycles_started++; 2273 } 2274 2275 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2276 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2277 2278 // We assume that if concurrent == true, then the caller is a 2279 // concurrent thread that was joined the Suspendible Thread 2280 // Set. If there's ever a cheap way to check this, we should add an 2281 // assert here. 2282 2283 // Given that this method is called at the end of a Full GC or of a 2284 // concurrent cycle, and those can be nested (i.e., a Full GC can 2285 // interrupt a concurrent cycle), the number of full collections 2286 // completed should be either one (in the case where there was no 2287 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2288 // behind the number of full collections started. 2289 2290 // This is the case for the inner caller, i.e. a Full GC. 2291 assert(concurrent || 2292 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2293 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2294 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2295 "is inconsistent with _old_marking_cycles_completed = %u", 2296 _old_marking_cycles_started, _old_marking_cycles_completed); 2297 2298 // This is the case for the outer caller, i.e. the concurrent cycle. 2299 assert(!concurrent || 2300 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2301 "for outer caller (concurrent cycle): " 2302 "_old_marking_cycles_started = %u " 2303 "is inconsistent with _old_marking_cycles_completed = %u", 2304 _old_marking_cycles_started, _old_marking_cycles_completed); 2305 2306 _old_marking_cycles_completed += 1; 2307 2308 // We need to clear the "in_progress" flag in the CM thread before 2309 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2310 // is set) so that if a waiter requests another System.gc() it doesn't 2311 // incorrectly see that a marking cycle is still in progress. 2312 if (concurrent) { 2313 _cmThread->set_idle(); 2314 } 2315 2316 // This notify_all() will ensure that a thread that called 2317 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2318 // and it's waiting for a full GC to finish will be woken up. It is 2319 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2320 FullGCCount_lock->notify_all(); 2321 } 2322 2323 void G1CollectedHeap::collect(GCCause::Cause cause) { 2324 assert_heap_not_locked(); 2325 2326 uint gc_count_before; 2327 uint old_marking_count_before; 2328 uint full_gc_count_before; 2329 bool retry_gc; 2330 2331 do { 2332 retry_gc = false; 2333 2334 { 2335 MutexLocker ml(Heap_lock); 2336 2337 // Read the GC count while holding the Heap_lock 2338 gc_count_before = total_collections(); 2339 full_gc_count_before = total_full_collections(); 2340 old_marking_count_before = _old_marking_cycles_started; 2341 } 2342 2343 if (should_do_concurrent_full_gc(cause)) { 2344 // Schedule an initial-mark evacuation pause that will start a 2345 // concurrent cycle. We're setting word_size to 0 which means that 2346 // we are not requesting a post-GC allocation. 2347 VM_G1IncCollectionPause op(gc_count_before, 2348 0, /* word_size */ 2349 true, /* should_initiate_conc_mark */ 2350 g1_policy()->max_pause_time_ms(), 2351 cause); 2352 op.set_allocation_context(AllocationContext::current()); 2353 2354 VMThread::execute(&op); 2355 if (!op.pause_succeeded()) { 2356 if (old_marking_count_before == _old_marking_cycles_started) { 2357 retry_gc = op.should_retry_gc(); 2358 } else { 2359 // A Full GC happened while we were trying to schedule the 2360 // initial-mark GC. No point in starting a new cycle given 2361 // that the whole heap was collected anyway. 2362 } 2363 2364 if (retry_gc) { 2365 if (GCLocker::is_active_and_needs_gc()) { 2366 GCLocker::stall_until_clear(); 2367 } 2368 } 2369 } 2370 } else { 2371 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2372 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2373 2374 // Schedule a standard evacuation pause. We're setting word_size 2375 // to 0 which means that we are not requesting a post-GC allocation. 2376 VM_G1IncCollectionPause op(gc_count_before, 2377 0, /* word_size */ 2378 false, /* should_initiate_conc_mark */ 2379 g1_policy()->max_pause_time_ms(), 2380 cause); 2381 VMThread::execute(&op); 2382 } else { 2383 // Schedule a Full GC. 2384 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2385 VMThread::execute(&op); 2386 } 2387 } 2388 } while (retry_gc); 2389 } 2390 2391 bool G1CollectedHeap::is_in(const void* p) const { 2392 if (_hrm.reserved().contains(p)) { 2393 // Given that we know that p is in the reserved space, 2394 // heap_region_containing() should successfully 2395 // return the containing region. 2396 HeapRegion* hr = heap_region_containing(p); 2397 return hr->is_in(p); 2398 } else { 2399 return false; 2400 } 2401 } 2402 2403 #ifdef ASSERT 2404 bool G1CollectedHeap::is_in_exact(const void* p) const { 2405 bool contains = reserved_region().contains(p); 2406 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2407 if (contains && available) { 2408 return true; 2409 } else { 2410 return false; 2411 } 2412 } 2413 #endif 2414 2415 bool G1CollectedHeap::obj_in_cs(oop obj) { 2416 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj); 2417 return r != NULL && r->in_collection_set(); 2418 } 2419 2420 // Iteration functions. 2421 2422 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2423 2424 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2425 ExtendedOopClosure* _cl; 2426 public: 2427 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2428 bool doHeapRegion(HeapRegion* r) { 2429 if (!r->is_continues_humongous()) { 2430 r->oop_iterate(_cl); 2431 } 2432 return false; 2433 } 2434 }; 2435 2436 // Iterates an ObjectClosure over all objects within a HeapRegion. 2437 2438 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2439 ObjectClosure* _cl; 2440 public: 2441 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2442 bool doHeapRegion(HeapRegion* r) { 2443 if (!r->is_continues_humongous()) { 2444 r->object_iterate(_cl); 2445 } 2446 return false; 2447 } 2448 }; 2449 2450 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2451 IterateObjectClosureRegionClosure blk(cl); 2452 heap_region_iterate(&blk); 2453 } 2454 2455 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2456 _hrm.iterate(cl); 2457 } 2458 2459 void 2460 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, 2461 uint worker_id, 2462 HeapRegionClaimer *hrclaimer, 2463 bool concurrent) const { 2464 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); 2465 } 2466 2467 // Clear the cached CSet starting regions and (more importantly) 2468 // the time stamps. Called when we reset the GC time stamp. 2469 void G1CollectedHeap::clear_cset_start_regions() { 2470 assert(_worker_cset_start_region != NULL, "sanity"); 2471 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2472 2473 for (uint i = 0; i < ParallelGCThreads; i++) { 2474 _worker_cset_start_region[i] = NULL; 2475 _worker_cset_start_region_time_stamp[i] = 0; 2476 } 2477 } 2478 2479 // Given the id of a worker, obtain or calculate a suitable 2480 // starting region for iterating over the current collection set. 2481 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2482 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2483 2484 HeapRegion* result = NULL; 2485 unsigned gc_time_stamp = get_gc_time_stamp(); 2486 2487 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2488 // Cached starting region for current worker was set 2489 // during the current pause - so it's valid. 2490 // Note: the cached starting heap region may be NULL 2491 // (when the collection set is empty). 2492 result = _worker_cset_start_region[worker_i]; 2493 assert(result == NULL || result->in_collection_set(), "sanity"); 2494 return result; 2495 } 2496 2497 // The cached entry was not valid so let's calculate 2498 // a suitable starting heap region for this worker. 2499 2500 // We want the parallel threads to start their collection 2501 // set iteration at different collection set regions to 2502 // avoid contention. 2503 // If we have: 2504 // n collection set regions 2505 // p threads 2506 // Then thread t will start at region floor ((t * n) / p) 2507 2508 result = collection_set()->head(); 2509 uint cs_size = collection_set()->region_length(); 2510 uint active_workers = workers()->active_workers(); 2511 2512 uint end_ind = (cs_size * worker_i) / active_workers; 2513 uint start_ind = 0; 2514 2515 if (worker_i > 0 && 2516 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2517 // Previous workers starting region is valid 2518 // so let's iterate from there 2519 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2520 OrderAccess::loadload(); 2521 result = _worker_cset_start_region[worker_i - 1]; 2522 } 2523 2524 for (uint i = start_ind; i < end_ind; i++) { 2525 result = result->next_in_collection_set(); 2526 } 2527 2528 // Note: the calculated starting heap region may be NULL 2529 // (when the collection set is empty). 2530 assert(result == NULL || result->in_collection_set(), "sanity"); 2531 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2532 "should be updated only once per pause"); 2533 _worker_cset_start_region[worker_i] = result; 2534 OrderAccess::storestore(); 2535 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2536 return result; 2537 } 2538 2539 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2540 HeapRegion* r = collection_set()->head(); 2541 while (r != NULL) { 2542 HeapRegion* next = r->next_in_collection_set(); 2543 if (cl->doHeapRegion(r)) { 2544 cl->incomplete(); 2545 return; 2546 } 2547 r = next; 2548 } 2549 } 2550 2551 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2552 HeapRegionClosure *cl) { 2553 if (r == NULL) { 2554 // The CSet is empty so there's nothing to do. 2555 return; 2556 } 2557 2558 assert(r->in_collection_set(), 2559 "Start region must be a member of the collection set."); 2560 HeapRegion* cur = r; 2561 while (cur != NULL) { 2562 HeapRegion* next = cur->next_in_collection_set(); 2563 if (cl->doHeapRegion(cur) && false) { 2564 cl->incomplete(); 2565 return; 2566 } 2567 cur = next; 2568 } 2569 cur = collection_set()->head(); 2570 while (cur != r) { 2571 HeapRegion* next = cur->next_in_collection_set(); 2572 if (cl->doHeapRegion(cur) && false) { 2573 cl->incomplete(); 2574 return; 2575 } 2576 cur = next; 2577 } 2578 } 2579 2580 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2581 HeapRegion* result = _hrm.next_region_in_heap(from); 2582 while (result != NULL && result->is_pinned()) { 2583 result = _hrm.next_region_in_heap(result); 2584 } 2585 return result; 2586 } 2587 2588 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2589 HeapRegion* hr = heap_region_containing(addr); 2590 return hr->block_start(addr); 2591 } 2592 2593 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2594 HeapRegion* hr = heap_region_containing(addr); 2595 return hr->block_size(addr); 2596 } 2597 2598 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2599 HeapRegion* hr = heap_region_containing(addr); 2600 return hr->block_is_obj(addr); 2601 } 2602 2603 bool G1CollectedHeap::supports_tlab_allocation() const { 2604 return true; 2605 } 2606 2607 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2608 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2609 } 2610 2611 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2612 return young_list()->eden_used_bytes(); 2613 } 2614 2615 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2616 // must be equal to the humongous object limit. 2617 size_t G1CollectedHeap::max_tlab_size() const { 2618 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment); 2619 } 2620 2621 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2622 AllocationContext_t context = AllocationContext::current(); 2623 return _allocator->unsafe_max_tlab_alloc(context); 2624 } 2625 2626 size_t G1CollectedHeap::max_capacity() const { 2627 return _hrm.reserved().byte_size(); 2628 } 2629 2630 jlong G1CollectedHeap::millis_since_last_gc() { 2631 // assert(false, "NYI"); 2632 return 0; 2633 } 2634 2635 void G1CollectedHeap::prepare_for_verify() { 2636 _verifier->prepare_for_verify(); 2637 } 2638 2639 void G1CollectedHeap::verify(VerifyOption vo) { 2640 _verifier->verify(vo); 2641 } 2642 2643 class PrintRegionClosure: public HeapRegionClosure { 2644 outputStream* _st; 2645 public: 2646 PrintRegionClosure(outputStream* st) : _st(st) {} 2647 bool doHeapRegion(HeapRegion* r) { 2648 r->print_on(_st); 2649 return false; 2650 } 2651 }; 2652 2653 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2654 const HeapRegion* hr, 2655 const VerifyOption vo) const { 2656 switch (vo) { 2657 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2658 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2659 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive(); 2660 default: ShouldNotReachHere(); 2661 } 2662 return false; // keep some compilers happy 2663 } 2664 2665 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2666 const VerifyOption vo) const { 2667 switch (vo) { 2668 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2669 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2670 case VerifyOption_G1UseMarkWord: { 2671 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj); 2672 return !obj->is_gc_marked() && !hr->is_archive(); 2673 } 2674 default: ShouldNotReachHere(); 2675 } 2676 return false; // keep some compilers happy 2677 } 2678 2679 void G1CollectedHeap::print_heap_regions() const { 2680 Log(gc, heap, region) log; 2681 if (log.is_trace()) { 2682 ResourceMark rm; 2683 print_regions_on(log.trace_stream()); 2684 } 2685 } 2686 2687 void G1CollectedHeap::print_on(outputStream* st) const { 2688 st->print(" %-20s", "garbage-first heap"); 2689 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2690 capacity()/K, used_unlocked()/K); 2691 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")", 2692 p2i(_hrm.reserved().start()), 2693 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords), 2694 p2i(_hrm.reserved().end())); 2695 st->cr(); 2696 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2697 uint young_regions = _young_list->length(); 2698 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2699 (size_t) young_regions * HeapRegion::GrainBytes / K); 2700 uint survivor_regions = _young_list->survivor_length(); 2701 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2702 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2703 st->cr(); 2704 MetaspaceAux::print_on(st); 2705 } 2706 2707 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2708 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2709 "HS=humongous(starts), HC=humongous(continues), " 2710 "CS=collection set, F=free, A=archive, TS=gc time stamp, " 2711 "AC=allocation context, " 2712 "TAMS=top-at-mark-start (previous, next)"); 2713 PrintRegionClosure blk(st); 2714 heap_region_iterate(&blk); 2715 } 2716 2717 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2718 print_on(st); 2719 2720 // Print the per-region information. 2721 print_regions_on(st); 2722 } 2723 2724 void G1CollectedHeap::print_on_error(outputStream* st) const { 2725 this->CollectedHeap::print_on_error(st); 2726 2727 if (_cm != NULL) { 2728 st->cr(); 2729 _cm->print_on_error(st); 2730 } 2731 } 2732 2733 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2734 workers()->print_worker_threads_on(st); 2735 _cmThread->print_on(st); 2736 st->cr(); 2737 _cm->print_worker_threads_on(st); 2738 _cg1r->print_worker_threads_on(st); 2739 if (G1StringDedup::is_enabled()) { 2740 G1StringDedup::print_worker_threads_on(st); 2741 } 2742 } 2743 2744 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2745 workers()->threads_do(tc); 2746 tc->do_thread(_cmThread); 2747 _cg1r->threads_do(tc); 2748 if (G1StringDedup::is_enabled()) { 2749 G1StringDedup::threads_do(tc); 2750 } 2751 } 2752 2753 void G1CollectedHeap::print_tracing_info() const { 2754 g1_rem_set()->print_summary_info(); 2755 concurrent_mark()->print_summary_info(); 2756 g1_policy()->print_yg_surv_rate_info(); 2757 } 2758 2759 #ifndef PRODUCT 2760 // Helpful for debugging RSet issues. 2761 2762 class PrintRSetsClosure : public HeapRegionClosure { 2763 private: 2764 const char* _msg; 2765 size_t _occupied_sum; 2766 2767 public: 2768 bool doHeapRegion(HeapRegion* r) { 2769 HeapRegionRemSet* hrrs = r->rem_set(); 2770 size_t occupied = hrrs->occupied(); 2771 _occupied_sum += occupied; 2772 2773 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2774 if (occupied == 0) { 2775 tty->print_cr(" RSet is empty"); 2776 } else { 2777 hrrs->print(); 2778 } 2779 tty->print_cr("----------"); 2780 return false; 2781 } 2782 2783 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2784 tty->cr(); 2785 tty->print_cr("========================================"); 2786 tty->print_cr("%s", msg); 2787 tty->cr(); 2788 } 2789 2790 ~PrintRSetsClosure() { 2791 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2792 tty->print_cr("========================================"); 2793 tty->cr(); 2794 } 2795 }; 2796 2797 void G1CollectedHeap::print_cset_rsets() { 2798 PrintRSetsClosure cl("Printing CSet RSets"); 2799 collection_set_iterate(&cl); 2800 } 2801 2802 void G1CollectedHeap::print_all_rsets() { 2803 PrintRSetsClosure cl("Printing All RSets");; 2804 heap_region_iterate(&cl); 2805 } 2806 #endif // PRODUCT 2807 2808 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2809 YoungList* young_list = heap()->young_list(); 2810 2811 size_t eden_used_bytes = young_list->eden_used_bytes(); 2812 size_t survivor_used_bytes = young_list->survivor_used_bytes(); 2813 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2814 2815 size_t eden_capacity_bytes = 2816 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2817 2818 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2819 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2820 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2821 } 2822 2823 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2824 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2825 stats->unused(), stats->used(), stats->region_end_waste(), 2826 stats->regions_filled(), stats->direct_allocated(), 2827 stats->failure_used(), stats->failure_waste()); 2828 } 2829 2830 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2831 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2832 gc_tracer->report_gc_heap_summary(when, heap_summary); 2833 2834 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2835 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2836 } 2837 2838 G1CollectedHeap* G1CollectedHeap::heap() { 2839 CollectedHeap* heap = Universe::heap(); 2840 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2841 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); 2842 return (G1CollectedHeap*)heap; 2843 } 2844 2845 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 2846 // always_do_update_barrier = false; 2847 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2848 // Fill TLAB's and such 2849 accumulate_statistics_all_tlabs(); 2850 ensure_parsability(true); 2851 2852 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2853 } 2854 2855 void G1CollectedHeap::gc_epilogue(bool full) { 2856 // we are at the end of the GC. Total collections has already been increased. 2857 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2858 2859 // FIXME: what is this about? 2860 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2861 // is set. 2862 #if defined(COMPILER2) || INCLUDE_JVMCI 2863 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2864 #endif 2865 // always_do_update_barrier = true; 2866 2867 resize_all_tlabs(); 2868 allocation_context_stats().update(full); 2869 2870 // We have just completed a GC. Update the soft reference 2871 // policy with the new heap occupancy 2872 Universe::update_heap_info_at_gc(); 2873 } 2874 2875 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2876 uint gc_count_before, 2877 bool* succeeded, 2878 GCCause::Cause gc_cause) { 2879 assert_heap_not_locked_and_not_at_safepoint(); 2880 VM_G1IncCollectionPause op(gc_count_before, 2881 word_size, 2882 false, /* should_initiate_conc_mark */ 2883 g1_policy()->max_pause_time_ms(), 2884 gc_cause); 2885 2886 op.set_allocation_context(AllocationContext::current()); 2887 VMThread::execute(&op); 2888 2889 HeapWord* result = op.result(); 2890 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 2891 assert(result == NULL || ret_succeeded, 2892 "the result should be NULL if the VM did not succeed"); 2893 *succeeded = ret_succeeded; 2894 2895 assert_heap_not_locked(); 2896 return result; 2897 } 2898 2899 void 2900 G1CollectedHeap::doConcurrentMark() { 2901 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 2902 if (!_cmThread->in_progress()) { 2903 _cmThread->set_started(); 2904 CGC_lock->notify(); 2905 } 2906 } 2907 2908 size_t G1CollectedHeap::pending_card_num() { 2909 size_t extra_cards = 0; 2910 JavaThread *curr = Threads::first(); 2911 while (curr != NULL) { 2912 DirtyCardQueue& dcq = curr->dirty_card_queue(); 2913 extra_cards += dcq.size(); 2914 curr = curr->next(); 2915 } 2916 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2917 size_t buffer_size = dcqs.buffer_size(); 2918 size_t buffer_num = dcqs.completed_buffers_num(); 2919 2920 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 2921 // in bytes - not the number of 'entries'. We need to convert 2922 // into a number of cards. 2923 return (buffer_size * buffer_num + extra_cards) / oopSize; 2924 } 2925 2926 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 2927 private: 2928 size_t _total_humongous; 2929 size_t _candidate_humongous; 2930 2931 DirtyCardQueue _dcq; 2932 2933 // We don't nominate objects with many remembered set entries, on 2934 // the assumption that such objects are likely still live. 2935 bool is_remset_small(HeapRegion* region) const { 2936 HeapRegionRemSet* const rset = region->rem_set(); 2937 return G1EagerReclaimHumongousObjectsWithStaleRefs 2938 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) 2939 : rset->is_empty(); 2940 } 2941 2942 bool is_typeArray_region(HeapRegion* region) const { 2943 return oop(region->bottom())->is_typeArray(); 2944 } 2945 2946 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { 2947 assert(region->is_starts_humongous(), "Must start a humongous object"); 2948 2949 // Candidate selection must satisfy the following constraints 2950 // while concurrent marking is in progress: 2951 // 2952 // * In order to maintain SATB invariants, an object must not be 2953 // reclaimed if it was allocated before the start of marking and 2954 // has not had its references scanned. Such an object must have 2955 // its references (including type metadata) scanned to ensure no 2956 // live objects are missed by the marking process. Objects 2957 // allocated after the start of concurrent marking don't need to 2958 // be scanned. 2959 // 2960 // * An object must not be reclaimed if it is on the concurrent 2961 // mark stack. Objects allocated after the start of concurrent 2962 // marking are never pushed on the mark stack. 2963 // 2964 // Nominating only objects allocated after the start of concurrent 2965 // marking is sufficient to meet both constraints. This may miss 2966 // some objects that satisfy the constraints, but the marking data 2967 // structures don't support efficiently performing the needed 2968 // additional tests or scrubbing of the mark stack. 2969 // 2970 // However, we presently only nominate is_typeArray() objects. 2971 // A humongous object containing references induces remembered 2972 // set entries on other regions. In order to reclaim such an 2973 // object, those remembered sets would need to be cleaned up. 2974 // 2975 // We also treat is_typeArray() objects specially, allowing them 2976 // to be reclaimed even if allocated before the start of 2977 // concurrent mark. For this we rely on mark stack insertion to 2978 // exclude is_typeArray() objects, preventing reclaiming an object 2979 // that is in the mark stack. We also rely on the metadata for 2980 // such objects to be built-in and so ensured to be kept live. 2981 // Frequent allocation and drop of large binary blobs is an 2982 // important use case for eager reclaim, and this special handling 2983 // may reduce needed headroom. 2984 2985 return is_typeArray_region(region) && is_remset_small(region); 2986 } 2987 2988 public: 2989 RegisterHumongousWithInCSetFastTestClosure() 2990 : _total_humongous(0), 2991 _candidate_humongous(0), 2992 _dcq(&JavaThread::dirty_card_queue_set()) { 2993 } 2994 2995 virtual bool doHeapRegion(HeapRegion* r) { 2996 if (!r->is_starts_humongous()) { 2997 return false; 2998 } 2999 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3000 3001 bool is_candidate = humongous_region_is_candidate(g1h, r); 3002 uint rindex = r->hrm_index(); 3003 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 3004 if (is_candidate) { 3005 _candidate_humongous++; 3006 g1h->register_humongous_region_with_cset(rindex); 3007 // Is_candidate already filters out humongous object with large remembered sets. 3008 // If we have a humongous object with a few remembered sets, we simply flush these 3009 // remembered set entries into the DCQS. That will result in automatic 3010 // re-evaluation of their remembered set entries during the following evacuation 3011 // phase. 3012 if (!r->rem_set()->is_empty()) { 3013 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 3014 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 3015 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 3016 HeapRegionRemSetIterator hrrs(r->rem_set()); 3017 size_t card_index; 3018 while (hrrs.has_next(card_index)) { 3019 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 3020 // The remembered set might contain references to already freed 3021 // regions. Filter out such entries to avoid failing card table 3022 // verification. 3023 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) { 3024 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 3025 *card_ptr = CardTableModRefBS::dirty_card_val(); 3026 _dcq.enqueue(card_ptr); 3027 } 3028 } 3029 } 3030 assert(hrrs.n_yielded() == r->rem_set()->occupied(), 3031 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", 3032 hrrs.n_yielded(), r->rem_set()->occupied()); 3033 r->rem_set()->clear_locked(); 3034 } 3035 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 3036 } 3037 _total_humongous++; 3038 3039 return false; 3040 } 3041 3042 size_t total_humongous() const { return _total_humongous; } 3043 size_t candidate_humongous() const { return _candidate_humongous; } 3044 3045 void flush_rem_set_entries() { _dcq.flush(); } 3046 }; 3047 3048 void G1CollectedHeap::register_humongous_regions_with_cset() { 3049 if (!G1EagerReclaimHumongousObjects) { 3050 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 3051 return; 3052 } 3053 double time = os::elapsed_counter(); 3054 3055 // Collect reclaim candidate information and register candidates with cset. 3056 RegisterHumongousWithInCSetFastTestClosure cl; 3057 heap_region_iterate(&cl); 3058 3059 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 3060 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 3061 cl.total_humongous(), 3062 cl.candidate_humongous()); 3063 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3064 3065 // Finally flush all remembered set entries to re-check into the global DCQS. 3066 cl.flush_rem_set_entries(); 3067 } 3068 3069 class VerifyRegionRemSetClosure : public HeapRegionClosure { 3070 public: 3071 bool doHeapRegion(HeapRegion* hr) { 3072 if (!hr->is_archive() && !hr->is_continues_humongous()) { 3073 hr->verify_rem_set(); 3074 } 3075 return false; 3076 } 3077 }; 3078 3079 #ifdef ASSERT 3080 class VerifyCSetClosure: public HeapRegionClosure { 3081 public: 3082 bool doHeapRegion(HeapRegion* hr) { 3083 // Here we check that the CSet region's RSet is ready for parallel 3084 // iteration. The fields that we'll verify are only manipulated 3085 // when the region is part of a CSet and is collected. Afterwards, 3086 // we reset these fields when we clear the region's RSet (when the 3087 // region is freed) so they are ready when the region is 3088 // re-allocated. The only exception to this is if there's an 3089 // evacuation failure and instead of freeing the region we leave 3090 // it in the heap. In that case, we reset these fields during 3091 // evacuation failure handling. 3092 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3093 3094 // Here's a good place to add any other checks we'd like to 3095 // perform on CSet regions. 3096 return false; 3097 } 3098 }; 3099 #endif // ASSERT 3100 3101 uint G1CollectedHeap::num_task_queues() const { 3102 return _task_queues->size(); 3103 } 3104 3105 #if TASKQUEUE_STATS 3106 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3107 st->print_raw_cr("GC Task Stats"); 3108 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3109 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3110 } 3111 3112 void G1CollectedHeap::print_taskqueue_stats() const { 3113 if (!log_is_enabled(Trace, gc, task, stats)) { 3114 return; 3115 } 3116 Log(gc, task, stats) log; 3117 ResourceMark rm; 3118 outputStream* st = log.trace_stream(); 3119 3120 print_taskqueue_stats_hdr(st); 3121 3122 TaskQueueStats totals; 3123 const uint n = num_task_queues(); 3124 for (uint i = 0; i < n; ++i) { 3125 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 3126 totals += task_queue(i)->stats; 3127 } 3128 st->print_raw("tot "); totals.print(st); st->cr(); 3129 3130 DEBUG_ONLY(totals.verify()); 3131 } 3132 3133 void G1CollectedHeap::reset_taskqueue_stats() { 3134 const uint n = num_task_queues(); 3135 for (uint i = 0; i < n; ++i) { 3136 task_queue(i)->stats.reset(); 3137 } 3138 } 3139 #endif // TASKQUEUE_STATS 3140 3141 void G1CollectedHeap::wait_for_root_region_scanning() { 3142 double scan_wait_start = os::elapsedTime(); 3143 // We have to wait until the CM threads finish scanning the 3144 // root regions as it's the only way to ensure that all the 3145 // objects on them have been correctly scanned before we start 3146 // moving them during the GC. 3147 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3148 double wait_time_ms = 0.0; 3149 if (waited) { 3150 double scan_wait_end = os::elapsedTime(); 3151 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3152 } 3153 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3154 } 3155 3156 bool 3157 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3158 assert_at_safepoint(true /* should_be_vm_thread */); 3159 guarantee(!is_gc_active(), "collection is not reentrant"); 3160 3161 if (GCLocker::check_active_before_gc()) { 3162 return false; 3163 } 3164 3165 _gc_timer_stw->register_gc_start(); 3166 3167 GCIdMark gc_id_mark; 3168 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3169 3170 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3171 ResourceMark rm; 3172 3173 wait_for_root_region_scanning(); 3174 3175 print_heap_before_gc(); 3176 print_heap_regions(); 3177 trace_heap_before_gc(_gc_tracer_stw); 3178 3179 _verifier->verify_region_sets_optional(); 3180 _verifier->verify_dirty_young_regions(); 3181 3182 // We should not be doing initial mark unless the conc mark thread is running 3183 if (!_cmThread->should_terminate()) { 3184 // This call will decide whether this pause is an initial-mark 3185 // pause. If it is, during_initial_mark_pause() will return true 3186 // for the duration of this pause. 3187 g1_policy()->decide_on_conc_mark_initiation(); 3188 } 3189 3190 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3191 assert(!collector_state()->during_initial_mark_pause() || 3192 collector_state()->gcs_are_young(), "sanity"); 3193 3194 // We also do not allow mixed GCs during marking. 3195 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity"); 3196 3197 // Record whether this pause is an initial mark. When the current 3198 // thread has completed its logging output and it's safe to signal 3199 // the CM thread, the flag's value in the policy has been reset. 3200 bool should_start_conc_mark = collector_state()->during_initial_mark_pause(); 3201 3202 // Inner scope for scope based logging, timers, and stats collection 3203 { 3204 EvacuationInfo evacuation_info; 3205 3206 if (collector_state()->during_initial_mark_pause()) { 3207 // We are about to start a marking cycle, so we increment the 3208 // full collection counter. 3209 increment_old_marking_cycles_started(); 3210 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 3211 } 3212 3213 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 3214 3215 GCTraceCPUTime tcpu; 3216 3217 FormatBuffer<> gc_string("Pause "); 3218 if (collector_state()->during_initial_mark_pause()) { 3219 gc_string.append("Initial Mark"); 3220 } else if (collector_state()->gcs_are_young()) { 3221 gc_string.append("Young"); 3222 } else { 3223 gc_string.append("Mixed"); 3224 } 3225 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true); 3226 3227 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 3228 workers()->active_workers(), 3229 Threads::number_of_non_daemon_threads()); 3230 workers()->set_active_workers(active_workers); 3231 3232 g1_policy()->note_gc_start(); 3233 3234 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3235 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3236 3237 // If the secondary_free_list is not empty, append it to the 3238 // free_list. No need to wait for the cleanup operation to finish; 3239 // the region allocation code will check the secondary_free_list 3240 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3241 // set, skip this step so that the region allocation code has to 3242 // get entries from the secondary_free_list. 3243 if (!G1StressConcRegionFreeing) { 3244 append_secondary_free_list_if_not_empty_with_lock(); 3245 } 3246 3247 G1HeapTransition heap_transition(this); 3248 size_t heap_used_bytes_before_gc = used(); 3249 3250 assert(check_young_list_well_formed(), "young list should be well formed"); 3251 3252 // Don't dynamically change the number of GC threads this early. A value of 3253 // 0 is used to indicate serial work. When parallel work is done, 3254 // it will be set. 3255 3256 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3257 IsGCActiveMark x; 3258 3259 gc_prologue(false); 3260 increment_total_collections(false /* full gc */); 3261 increment_gc_time_stamp(); 3262 3263 if (VerifyRememberedSets) { 3264 log_info(gc, verify)("[Verifying RemSets before GC]"); 3265 VerifyRegionRemSetClosure v_cl; 3266 heap_region_iterate(&v_cl); 3267 } 3268 3269 _verifier->verify_before_gc(); 3270 3271 _verifier->check_bitmaps("GC Start"); 3272 3273 #if defined(COMPILER2) || INCLUDE_JVMCI 3274 DerivedPointerTable::clear(); 3275 #endif 3276 3277 // Please see comment in g1CollectedHeap.hpp and 3278 // G1CollectedHeap::ref_processing_init() to see how 3279 // reference processing currently works in G1. 3280 3281 // Enable discovery in the STW reference processor 3282 if (g1_policy()->should_process_references()) { 3283 ref_processor_stw()->enable_discovery(); 3284 } else { 3285 ref_processor_stw()->disable_discovery(); 3286 } 3287 3288 { 3289 // We want to temporarily turn off discovery by the 3290 // CM ref processor, if necessary, and turn it back on 3291 // on again later if we do. Using a scoped 3292 // NoRefDiscovery object will do this. 3293 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3294 3295 // Forget the current alloc region (we might even choose it to be part 3296 // of the collection set!). 3297 _allocator->release_mutator_alloc_region(); 3298 3299 // This timing is only used by the ergonomics to handle our pause target. 3300 // It is unclear why this should not include the full pause. We will 3301 // investigate this in CR 7178365. 3302 // 3303 // Preserving the old comment here if that helps the investigation: 3304 // 3305 // The elapsed time induced by the start time below deliberately elides 3306 // the possible verification above. 3307 double sample_start_time_sec = os::elapsedTime(); 3308 3309 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3310 3311 if (collector_state()->during_initial_mark_pause()) { 3312 concurrent_mark()->checkpointRootsInitialPre(); 3313 } 3314 3315 g1_policy()->finalize_collection_set(target_pause_time_ms); 3316 3317 evacuation_info.set_collectionset_regions(collection_set()->region_length()); 3318 3319 // Make sure the remembered sets are up to date. This needs to be 3320 // done before register_humongous_regions_with_cset(), because the 3321 // remembered sets are used there to choose eager reclaim candidates. 3322 // If the remembered sets are not up to date we might miss some 3323 // entries that need to be handled. 3324 g1_rem_set()->cleanupHRRS(); 3325 3326 register_humongous_regions_with_cset(); 3327 3328 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3329 3330 _cm->note_start_of_gc(); 3331 // We call this after finalize_cset() to 3332 // ensure that the CSet has been finalized. 3333 _cm->verify_no_cset_oops(); 3334 3335 if (_hr_printer.is_active()) { 3336 HeapRegion* hr = collection_set()->head(); 3337 while (hr != NULL) { 3338 _hr_printer.cset(hr); 3339 hr = hr->next_in_collection_set(); 3340 } 3341 } 3342 3343 #ifdef ASSERT 3344 VerifyCSetClosure cl; 3345 collection_set_iterate(&cl); 3346 #endif // ASSERT 3347 3348 // Initialize the GC alloc regions. 3349 _allocator->init_gc_alloc_regions(evacuation_info); 3350 3351 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length()); 3352 pre_evacuate_collection_set(); 3353 3354 // Actually do the work... 3355 evacuate_collection_set(evacuation_info, &per_thread_states); 3356 3357 post_evacuate_collection_set(evacuation_info, &per_thread_states); 3358 3359 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 3360 free_collection_set(collection_set()->head(), evacuation_info, surviving_young_words); 3361 3362 eagerly_reclaim_humongous_regions(); 3363 3364 collection_set()->clear_head(); 3365 3366 record_obj_copy_mem_stats(); 3367 _survivor_evac_stats.adjust_desired_plab_sz(); 3368 _old_evac_stats.adjust_desired_plab_sz(); 3369 3370 // Start a new incremental collection set for the next pause. 3371 collection_set()->start_incremental_building(); 3372 3373 clear_cset_fast_test(); 3374 3375 // Don't check the whole heap at this point as the 3376 // GC alloc regions from this pause have been tagged 3377 // as survivors and moved on to the survivor list. 3378 // Survivor regions will fail the !is_young() check. 3379 assert(check_young_list_empty(false /* check_heap */), 3380 "young list should be empty"); 3381 3382 _young_list->reset_auxilary_lists(); 3383 3384 if (evacuation_failed()) { 3385 set_used(recalculate_used()); 3386 if (_archive_allocator != NULL) { 3387 _archive_allocator->clear_used(); 3388 } 3389 for (uint i = 0; i < ParallelGCThreads; i++) { 3390 if (_evacuation_failed_info_array[i].has_failed()) { 3391 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3392 } 3393 } 3394 } else { 3395 // The "used" of the the collection set have already been subtracted 3396 // when they were freed. Add in the bytes evacuated. 3397 increase_used(g1_policy()->bytes_copied_during_gc()); 3398 } 3399 3400 if (collector_state()->during_initial_mark_pause()) { 3401 // We have to do this before we notify the CM threads that 3402 // they can start working to make sure that all the 3403 // appropriate initialization is done on the CM object. 3404 concurrent_mark()->checkpointRootsInitialPost(); 3405 collector_state()->set_mark_in_progress(true); 3406 // Note that we don't actually trigger the CM thread at 3407 // this point. We do that later when we're sure that 3408 // the current thread has completed its logging output. 3409 } 3410 3411 allocate_dummy_regions(); 3412 3413 _allocator->init_mutator_alloc_region(); 3414 3415 { 3416 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 3417 if (expand_bytes > 0) { 3418 size_t bytes_before = capacity(); 3419 // No need for an ergo logging here, 3420 // expansion_amount() does this when it returns a value > 0. 3421 double expand_ms; 3422 if (!expand(expand_bytes, &expand_ms)) { 3423 // We failed to expand the heap. Cannot do anything about it. 3424 } 3425 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 3426 } 3427 } 3428 3429 // We redo the verification but now wrt to the new CSet which 3430 // has just got initialized after the previous CSet was freed. 3431 _cm->verify_no_cset_oops(); 3432 _cm->note_end_of_gc(); 3433 3434 // This timing is only used by the ergonomics to handle our pause target. 3435 // It is unclear why this should not include the full pause. We will 3436 // investigate this in CR 7178365. 3437 double sample_end_time_sec = os::elapsedTime(); 3438 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3439 size_t total_cards_scanned = per_thread_states.total_cards_scanned(); 3440 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc); 3441 3442 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3443 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 3444 3445 MemoryService::track_memory_usage(); 3446 3447 // In prepare_for_verify() below we'll need to scan the deferred 3448 // update buffers to bring the RSets up-to-date if 3449 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 3450 // the update buffers we'll probably need to scan cards on the 3451 // regions we just allocated to (i.e., the GC alloc 3452 // regions). However, during the last GC we called 3453 // set_saved_mark() on all the GC alloc regions, so card 3454 // scanning might skip the [saved_mark_word()...top()] area of 3455 // those regions (i.e., the area we allocated objects into 3456 // during the last GC). But it shouldn't. Given that 3457 // saved_mark_word() is conditional on whether the GC time stamp 3458 // on the region is current or not, by incrementing the GC time 3459 // stamp here we invalidate all the GC time stamps on all the 3460 // regions and saved_mark_word() will simply return top() for 3461 // all the regions. This is a nicer way of ensuring this rather 3462 // than iterating over the regions and fixing them. In fact, the 3463 // GC time stamp increment here also ensures that 3464 // saved_mark_word() will return top() between pauses, i.e., 3465 // during concurrent refinement. So we don't need the 3466 // is_gc_active() check to decided which top to use when 3467 // scanning cards (see CR 7039627). 3468 increment_gc_time_stamp(); 3469 3470 if (VerifyRememberedSets) { 3471 log_info(gc, verify)("[Verifying RemSets after GC]"); 3472 VerifyRegionRemSetClosure v_cl; 3473 heap_region_iterate(&v_cl); 3474 } 3475 3476 _verifier->verify_after_gc(); 3477 _verifier->check_bitmaps("GC End"); 3478 3479 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 3480 ref_processor_stw()->verify_no_references_recorded(); 3481 3482 // CM reference discovery will be re-enabled if necessary. 3483 } 3484 3485 #ifdef TRACESPINNING 3486 ParallelTaskTerminator::print_termination_counts(); 3487 #endif 3488 3489 gc_epilogue(false); 3490 } 3491 3492 // Print the remainder of the GC log output. 3493 if (evacuation_failed()) { 3494 log_info(gc)("To-space exhausted"); 3495 } 3496 3497 g1_policy()->print_phases(); 3498 heap_transition.print(); 3499 3500 // It is not yet to safe to tell the concurrent mark to 3501 // start as we have some optional output below. We don't want the 3502 // output from the concurrent mark thread interfering with this 3503 // logging output either. 3504 3505 _hrm.verify_optional(); 3506 _verifier->verify_region_sets_optional(); 3507 3508 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3509 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3510 3511 print_heap_after_gc(); 3512 print_heap_regions(); 3513 trace_heap_after_gc(_gc_tracer_stw); 3514 3515 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3516 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3517 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3518 // before any GC notifications are raised. 3519 g1mm()->update_sizes(); 3520 3521 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3522 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 3523 _gc_timer_stw->register_gc_end(); 3524 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3525 } 3526 // It should now be safe to tell the concurrent mark thread to start 3527 // without its logging output interfering with the logging output 3528 // that came from the pause. 3529 3530 if (should_start_conc_mark) { 3531 // CAUTION: after the doConcurrentMark() call below, 3532 // the concurrent marking thread(s) could be running 3533 // concurrently with us. Make sure that anything after 3534 // this point does not assume that we are the only GC thread 3535 // running. Note: of course, the actual marking work will 3536 // not start until the safepoint itself is released in 3537 // SuspendibleThreadSet::desynchronize(). 3538 doConcurrentMark(); 3539 } 3540 3541 return true; 3542 } 3543 3544 void G1CollectedHeap::restore_preserved_marks() { 3545 G1RestorePreservedMarksTask rpm_task(_preserved_objs); 3546 workers()->run_task(&rpm_task); 3547 } 3548 3549 void G1CollectedHeap::remove_self_forwarding_pointers() { 3550 G1ParRemoveSelfForwardPtrsTask rsfp_task; 3551 workers()->run_task(&rsfp_task); 3552 } 3553 3554 void G1CollectedHeap::restore_after_evac_failure() { 3555 double remove_self_forwards_start = os::elapsedTime(); 3556 3557 remove_self_forwarding_pointers(); 3558 restore_preserved_marks(); 3559 3560 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3561 } 3562 3563 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 3564 if (!_evacuation_failed) { 3565 _evacuation_failed = true; 3566 } 3567 3568 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3569 3570 // We want to call the "for_promotion_failure" version only in the 3571 // case of a promotion failure. 3572 if (m->must_be_preserved_for_promotion_failure(obj)) { 3573 OopAndMarkOop elem(obj, m); 3574 _preserved_objs[worker_id].push(elem); 3575 } 3576 } 3577 3578 bool G1ParEvacuateFollowersClosure::offer_termination() { 3579 G1ParScanThreadState* const pss = par_scan_state(); 3580 start_term_time(); 3581 const bool res = terminator()->offer_termination(); 3582 end_term_time(); 3583 return res; 3584 } 3585 3586 void G1ParEvacuateFollowersClosure::do_void() { 3587 G1ParScanThreadState* const pss = par_scan_state(); 3588 pss->trim_queue(); 3589 do { 3590 pss->steal_and_trim_queue(queues()); 3591 } while (!offer_termination()); 3592 } 3593 3594 class G1ParTask : public AbstractGangTask { 3595 protected: 3596 G1CollectedHeap* _g1h; 3597 G1ParScanThreadStateSet* _pss; 3598 RefToScanQueueSet* _queues; 3599 G1RootProcessor* _root_processor; 3600 ParallelTaskTerminator _terminator; 3601 uint _n_workers; 3602 3603 public: 3604 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 3605 : AbstractGangTask("G1 collection"), 3606 _g1h(g1h), 3607 _pss(per_thread_states), 3608 _queues(task_queues), 3609 _root_processor(root_processor), 3610 _terminator(n_workers, _queues), 3611 _n_workers(n_workers) 3612 {} 3613 3614 void work(uint worker_id) { 3615 if (worker_id >= _n_workers) return; // no work needed this round 3616 3617 double start_sec = os::elapsedTime(); 3618 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 3619 3620 { 3621 ResourceMark rm; 3622 HandleMark hm; 3623 3624 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 3625 3626 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3627 pss->set_ref_processor(rp); 3628 3629 double start_strong_roots_sec = os::elapsedTime(); 3630 3631 _root_processor->evacuate_roots(pss->closures(), worker_id); 3632 3633 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss); 3634 3635 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid 3636 // treating the nmethods visited to act as roots for concurrent marking. 3637 // We only want to make sure that the oops in the nmethods are adjusted with regard to the 3638 // objects copied by the current evacuation. 3639 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl, 3640 pss->closures()->weak_codeblobs(), 3641 worker_id); 3642 3643 _pss->add_cards_scanned(worker_id, cards_scanned); 3644 3645 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 3646 3647 double term_sec = 0.0; 3648 size_t evac_term_attempts = 0; 3649 { 3650 double start = os::elapsedTime(); 3651 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator); 3652 evac.do_void(); 3653 3654 evac_term_attempts = evac.term_attempts(); 3655 term_sec = evac.term_time(); 3656 double elapsed_sec = os::elapsedTime() - start; 3657 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 3658 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 3659 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 3660 } 3661 3662 assert(pss->queue_is_empty(), "should be empty"); 3663 3664 if (log_is_enabled(Debug, gc, task, stats)) { 3665 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3666 size_t lab_waste; 3667 size_t lab_undo_waste; 3668 pss->waste(lab_waste, lab_undo_waste); 3669 _g1h->print_termination_stats(worker_id, 3670 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 3671 strong_roots_sec * 1000.0, /* strong roots time */ 3672 term_sec * 1000.0, /* evac term time */ 3673 evac_term_attempts, /* evac term attempts */ 3674 lab_waste, /* alloc buffer waste */ 3675 lab_undo_waste /* undo waste */ 3676 ); 3677 } 3678 3679 // Close the inner scope so that the ResourceMark and HandleMark 3680 // destructors are executed here and are included as part of the 3681 // "GC Worker Time". 3682 } 3683 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 3684 } 3685 }; 3686 3687 void G1CollectedHeap::print_termination_stats_hdr() { 3688 log_debug(gc, task, stats)("GC Termination Stats"); 3689 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 3690 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo"); 3691 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 3692 } 3693 3694 void G1CollectedHeap::print_termination_stats(uint worker_id, 3695 double elapsed_ms, 3696 double strong_roots_ms, 3697 double term_ms, 3698 size_t term_attempts, 3699 size_t alloc_buffer_waste, 3700 size_t undo_waste) const { 3701 log_debug(gc, task, stats) 3702 ("%3d %9.2f %9.2f %6.2f " 3703 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 3704 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 3705 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 3706 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 3707 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 3708 alloc_buffer_waste * HeapWordSize / K, 3709 undo_waste * HeapWordSize / K); 3710 } 3711 3712 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 3713 private: 3714 BoolObjectClosure* _is_alive; 3715 int _initial_string_table_size; 3716 int _initial_symbol_table_size; 3717 3718 bool _process_strings; 3719 int _strings_processed; 3720 int _strings_removed; 3721 3722 bool _process_symbols; 3723 int _symbols_processed; 3724 int _symbols_removed; 3725 3726 public: 3727 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 3728 AbstractGangTask("String/Symbol Unlinking"), 3729 _is_alive(is_alive), 3730 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 3731 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 3732 3733 _initial_string_table_size = StringTable::the_table()->table_size(); 3734 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 3735 if (process_strings) { 3736 StringTable::clear_parallel_claimed_index(); 3737 } 3738 if (process_symbols) { 3739 SymbolTable::clear_parallel_claimed_index(); 3740 } 3741 } 3742 3743 ~G1StringSymbolTableUnlinkTask() { 3744 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 3745 "claim value %d after unlink less than initial string table size %d", 3746 StringTable::parallel_claimed_index(), _initial_string_table_size); 3747 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 3748 "claim value %d after unlink less than initial symbol table size %d", 3749 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size); 3750 3751 log_info(gc, stringtable)( 3752 "Cleaned string and symbol table, " 3753 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, " 3754 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed", 3755 strings_processed(), strings_removed(), 3756 symbols_processed(), symbols_removed()); 3757 } 3758 3759 void work(uint worker_id) { 3760 int strings_processed = 0; 3761 int strings_removed = 0; 3762 int symbols_processed = 0; 3763 int symbols_removed = 0; 3764 if (_process_strings) { 3765 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 3766 Atomic::add(strings_processed, &_strings_processed); 3767 Atomic::add(strings_removed, &_strings_removed); 3768 } 3769 if (_process_symbols) { 3770 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 3771 Atomic::add(symbols_processed, &_symbols_processed); 3772 Atomic::add(symbols_removed, &_symbols_removed); 3773 } 3774 } 3775 3776 size_t strings_processed() const { return (size_t)_strings_processed; } 3777 size_t strings_removed() const { return (size_t)_strings_removed; } 3778 3779 size_t symbols_processed() const { return (size_t)_symbols_processed; } 3780 size_t symbols_removed() const { return (size_t)_symbols_removed; } 3781 }; 3782 3783 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 3784 private: 3785 static Monitor* _lock; 3786 3787 BoolObjectClosure* const _is_alive; 3788 const bool _unloading_occurred; 3789 const uint _num_workers; 3790 3791 // Variables used to claim nmethods. 3792 nmethod* _first_nmethod; 3793 volatile nmethod* _claimed_nmethod; 3794 3795 // The list of nmethods that need to be processed by the second pass. 3796 volatile nmethod* _postponed_list; 3797 volatile uint _num_entered_barrier; 3798 3799 public: 3800 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 3801 _is_alive(is_alive), 3802 _unloading_occurred(unloading_occurred), 3803 _num_workers(num_workers), 3804 _first_nmethod(NULL), 3805 _claimed_nmethod(NULL), 3806 _postponed_list(NULL), 3807 _num_entered_barrier(0) 3808 { 3809 nmethod::increase_unloading_clock(); 3810 // Get first alive nmethod 3811 NMethodIterator iter = NMethodIterator(); 3812 if(iter.next_alive()) { 3813 _first_nmethod = iter.method(); 3814 } 3815 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 3816 } 3817 3818 ~G1CodeCacheUnloadingTask() { 3819 CodeCache::verify_clean_inline_caches(); 3820 3821 CodeCache::set_needs_cache_clean(false); 3822 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 3823 3824 CodeCache::verify_icholder_relocations(); 3825 } 3826 3827 private: 3828 void add_to_postponed_list(nmethod* nm) { 3829 nmethod* old; 3830 do { 3831 old = (nmethod*)_postponed_list; 3832 nm->set_unloading_next(old); 3833 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 3834 } 3835 3836 void clean_nmethod(nmethod* nm) { 3837 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 3838 3839 if (postponed) { 3840 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 3841 add_to_postponed_list(nm); 3842 } 3843 3844 // Mark that this thread has been cleaned/unloaded. 3845 // After this call, it will be safe to ask if this nmethod was unloaded or not. 3846 nm->set_unloading_clock(nmethod::global_unloading_clock()); 3847 } 3848 3849 void clean_nmethod_postponed(nmethod* nm) { 3850 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 3851 } 3852 3853 static const int MaxClaimNmethods = 16; 3854 3855 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 3856 nmethod* first; 3857 NMethodIterator last; 3858 3859 do { 3860 *num_claimed_nmethods = 0; 3861 3862 first = (nmethod*)_claimed_nmethod; 3863 last = NMethodIterator(first); 3864 3865 if (first != NULL) { 3866 3867 for (int i = 0; i < MaxClaimNmethods; i++) { 3868 if (!last.next_alive()) { 3869 break; 3870 } 3871 claimed_nmethods[i] = last.method(); 3872 (*num_claimed_nmethods)++; 3873 } 3874 } 3875 3876 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 3877 } 3878 3879 nmethod* claim_postponed_nmethod() { 3880 nmethod* claim; 3881 nmethod* next; 3882 3883 do { 3884 claim = (nmethod*)_postponed_list; 3885 if (claim == NULL) { 3886 return NULL; 3887 } 3888 3889 next = claim->unloading_next(); 3890 3891 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 3892 3893 return claim; 3894 } 3895 3896 public: 3897 // Mark that we're done with the first pass of nmethod cleaning. 3898 void barrier_mark(uint worker_id) { 3899 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3900 _num_entered_barrier++; 3901 if (_num_entered_barrier == _num_workers) { 3902 ml.notify_all(); 3903 } 3904 } 3905 3906 // See if we have to wait for the other workers to 3907 // finish their first-pass nmethod cleaning work. 3908 void barrier_wait(uint worker_id) { 3909 if (_num_entered_barrier < _num_workers) { 3910 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3911 while (_num_entered_barrier < _num_workers) { 3912 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 3913 } 3914 } 3915 } 3916 3917 // Cleaning and unloading of nmethods. Some work has to be postponed 3918 // to the second pass, when we know which nmethods survive. 3919 void work_first_pass(uint worker_id) { 3920 // The first nmethods is claimed by the first worker. 3921 if (worker_id == 0 && _first_nmethod != NULL) { 3922 clean_nmethod(_first_nmethod); 3923 _first_nmethod = NULL; 3924 } 3925 3926 int num_claimed_nmethods; 3927 nmethod* claimed_nmethods[MaxClaimNmethods]; 3928 3929 while (true) { 3930 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 3931 3932 if (num_claimed_nmethods == 0) { 3933 break; 3934 } 3935 3936 for (int i = 0; i < num_claimed_nmethods; i++) { 3937 clean_nmethod(claimed_nmethods[i]); 3938 } 3939 } 3940 } 3941 3942 void work_second_pass(uint worker_id) { 3943 nmethod* nm; 3944 // Take care of postponed nmethods. 3945 while ((nm = claim_postponed_nmethod()) != NULL) { 3946 clean_nmethod_postponed(nm); 3947 } 3948 } 3949 }; 3950 3951 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 3952 3953 class G1KlassCleaningTask : public StackObj { 3954 BoolObjectClosure* _is_alive; 3955 volatile jint _clean_klass_tree_claimed; 3956 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 3957 3958 public: 3959 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 3960 _is_alive(is_alive), 3961 _clean_klass_tree_claimed(0), 3962 _klass_iterator() { 3963 } 3964 3965 private: 3966 bool claim_clean_klass_tree_task() { 3967 if (_clean_klass_tree_claimed) { 3968 return false; 3969 } 3970 3971 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 3972 } 3973 3974 InstanceKlass* claim_next_klass() { 3975 Klass* klass; 3976 do { 3977 klass =_klass_iterator.next_klass(); 3978 } while (klass != NULL && !klass->is_instance_klass()); 3979 3980 // this can be null so don't call InstanceKlass::cast 3981 return static_cast<InstanceKlass*>(klass); 3982 } 3983 3984 public: 3985 3986 void clean_klass(InstanceKlass* ik) { 3987 ik->clean_weak_instanceklass_links(_is_alive); 3988 } 3989 3990 void work() { 3991 ResourceMark rm; 3992 3993 // One worker will clean the subklass/sibling klass tree. 3994 if (claim_clean_klass_tree_task()) { 3995 Klass::clean_subklass_tree(_is_alive); 3996 } 3997 3998 // All workers will help cleaning the classes, 3999 InstanceKlass* klass; 4000 while ((klass = claim_next_klass()) != NULL) { 4001 clean_klass(klass); 4002 } 4003 } 4004 }; 4005 4006 // To minimize the remark pause times, the tasks below are done in parallel. 4007 class G1ParallelCleaningTask : public AbstractGangTask { 4008 private: 4009 G1StringSymbolTableUnlinkTask _string_symbol_task; 4010 G1CodeCacheUnloadingTask _code_cache_task; 4011 G1KlassCleaningTask _klass_cleaning_task; 4012 4013 public: 4014 // The constructor is run in the VMThread. 4015 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 4016 AbstractGangTask("Parallel Cleaning"), 4017 _string_symbol_task(is_alive, process_strings, process_symbols), 4018 _code_cache_task(num_workers, is_alive, unloading_occurred), 4019 _klass_cleaning_task(is_alive) { 4020 } 4021 4022 // The parallel work done by all worker threads. 4023 void work(uint worker_id) { 4024 // Do first pass of code cache cleaning. 4025 _code_cache_task.work_first_pass(worker_id); 4026 4027 // Let the threads mark that the first pass is done. 4028 _code_cache_task.barrier_mark(worker_id); 4029 4030 // Clean the Strings and Symbols. 4031 _string_symbol_task.work(worker_id); 4032 4033 // Wait for all workers to finish the first code cache cleaning pass. 4034 _code_cache_task.barrier_wait(worker_id); 4035 4036 // Do the second code cache cleaning work, which realize on 4037 // the liveness information gathered during the first pass. 4038 _code_cache_task.work_second_pass(worker_id); 4039 4040 // Clean all klasses that were not unloaded. 4041 _klass_cleaning_task.work(); 4042 } 4043 }; 4044 4045 4046 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 4047 bool process_strings, 4048 bool process_symbols, 4049 bool class_unloading_occurred) { 4050 uint n_workers = workers()->active_workers(); 4051 4052 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 4053 n_workers, class_unloading_occurred); 4054 workers()->run_task(&g1_unlink_task); 4055 } 4056 4057 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 4058 bool process_strings, bool process_symbols) { 4059 { // Timing scope 4060 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 4061 workers()->run_task(&g1_unlink_task); 4062 } 4063 } 4064 4065 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 4066 private: 4067 DirtyCardQueueSet* _queue; 4068 G1CollectedHeap* _g1h; 4069 public: 4070 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 4071 _queue(queue), _g1h(g1h) { } 4072 4073 virtual void work(uint worker_id) { 4074 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 4075 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 4076 4077 RedirtyLoggedCardTableEntryClosure cl(_g1h); 4078 _queue->par_apply_closure_to_all_completed_buffers(&cl); 4079 4080 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 4081 } 4082 }; 4083 4084 void G1CollectedHeap::redirty_logged_cards() { 4085 double redirty_logged_cards_start = os::elapsedTime(); 4086 4087 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 4088 dirty_card_queue_set().reset_for_par_iteration(); 4089 workers()->run_task(&redirty_task); 4090 4091 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 4092 dcq.merge_bufferlists(&dirty_card_queue_set()); 4093 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 4094 4095 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 4096 } 4097 4098 // Weak Reference Processing support 4099 4100 // An always "is_alive" closure that is used to preserve referents. 4101 // If the object is non-null then it's alive. Used in the preservation 4102 // of referent objects that are pointed to by reference objects 4103 // discovered by the CM ref processor. 4104 class G1AlwaysAliveClosure: public BoolObjectClosure { 4105 G1CollectedHeap* _g1; 4106 public: 4107 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4108 bool do_object_b(oop p) { 4109 if (p != NULL) { 4110 return true; 4111 } 4112 return false; 4113 } 4114 }; 4115 4116 bool G1STWIsAliveClosure::do_object_b(oop p) { 4117 // An object is reachable if it is outside the collection set, 4118 // or is inside and copied. 4119 return !_g1->is_in_cset(p) || p->is_forwarded(); 4120 } 4121 4122 // Non Copying Keep Alive closure 4123 class G1KeepAliveClosure: public OopClosure { 4124 G1CollectedHeap* _g1; 4125 public: 4126 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4127 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 4128 void do_oop(oop* p) { 4129 oop obj = *p; 4130 assert(obj != NULL, "the caller should have filtered out NULL values"); 4131 4132 const InCSetState cset_state = _g1->in_cset_state(obj); 4133 if (!cset_state.is_in_cset_or_humongous()) { 4134 return; 4135 } 4136 if (cset_state.is_in_cset()) { 4137 assert( obj->is_forwarded(), "invariant" ); 4138 *p = obj->forwardee(); 4139 } else { 4140 assert(!obj->is_forwarded(), "invariant" ); 4141 assert(cset_state.is_humongous(), 4142 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 4143 _g1->set_humongous_is_live(obj); 4144 } 4145 } 4146 }; 4147 4148 // Copying Keep Alive closure - can be called from both 4149 // serial and parallel code as long as different worker 4150 // threads utilize different G1ParScanThreadState instances 4151 // and different queues. 4152 4153 class G1CopyingKeepAliveClosure: public OopClosure { 4154 G1CollectedHeap* _g1h; 4155 OopClosure* _copy_non_heap_obj_cl; 4156 G1ParScanThreadState* _par_scan_state; 4157 4158 public: 4159 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 4160 OopClosure* non_heap_obj_cl, 4161 G1ParScanThreadState* pss): 4162 _g1h(g1h), 4163 _copy_non_heap_obj_cl(non_heap_obj_cl), 4164 _par_scan_state(pss) 4165 {} 4166 4167 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 4168 virtual void do_oop( oop* p) { do_oop_work(p); } 4169 4170 template <class T> void do_oop_work(T* p) { 4171 oop obj = oopDesc::load_decode_heap_oop(p); 4172 4173 if (_g1h->is_in_cset_or_humongous(obj)) { 4174 // If the referent object has been forwarded (either copied 4175 // to a new location or to itself in the event of an 4176 // evacuation failure) then we need to update the reference 4177 // field and, if both reference and referent are in the G1 4178 // heap, update the RSet for the referent. 4179 // 4180 // If the referent has not been forwarded then we have to keep 4181 // it alive by policy. Therefore we have copy the referent. 4182 // 4183 // If the reference field is in the G1 heap then we can push 4184 // on the PSS queue. When the queue is drained (after each 4185 // phase of reference processing) the object and it's followers 4186 // will be copied, the reference field set to point to the 4187 // new location, and the RSet updated. Otherwise we need to 4188 // use the the non-heap or metadata closures directly to copy 4189 // the referent object and update the pointer, while avoiding 4190 // updating the RSet. 4191 4192 if (_g1h->is_in_g1_reserved(p)) { 4193 _par_scan_state->push_on_queue(p); 4194 } else { 4195 assert(!Metaspace::contains((const void*)p), 4196 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)); 4197 _copy_non_heap_obj_cl->do_oop(p); 4198 } 4199 } 4200 } 4201 }; 4202 4203 // Serial drain queue closure. Called as the 'complete_gc' 4204 // closure for each discovered list in some of the 4205 // reference processing phases. 4206 4207 class G1STWDrainQueueClosure: public VoidClosure { 4208 protected: 4209 G1CollectedHeap* _g1h; 4210 G1ParScanThreadState* _par_scan_state; 4211 4212 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4213 4214 public: 4215 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 4216 _g1h(g1h), 4217 _par_scan_state(pss) 4218 { } 4219 4220 void do_void() { 4221 G1ParScanThreadState* const pss = par_scan_state(); 4222 pss->trim_queue(); 4223 } 4224 }; 4225 4226 // Parallel Reference Processing closures 4227 4228 // Implementation of AbstractRefProcTaskExecutor for parallel reference 4229 // processing during G1 evacuation pauses. 4230 4231 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 4232 private: 4233 G1CollectedHeap* _g1h; 4234 G1ParScanThreadStateSet* _pss; 4235 RefToScanQueueSet* _queues; 4236 WorkGang* _workers; 4237 uint _active_workers; 4238 4239 public: 4240 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 4241 G1ParScanThreadStateSet* per_thread_states, 4242 WorkGang* workers, 4243 RefToScanQueueSet *task_queues, 4244 uint n_workers) : 4245 _g1h(g1h), 4246 _pss(per_thread_states), 4247 _queues(task_queues), 4248 _workers(workers), 4249 _active_workers(n_workers) 4250 { 4251 g1h->ref_processor_stw()->set_active_mt_degree(n_workers); 4252 } 4253 4254 // Executes the given task using concurrent marking worker threads. 4255 virtual void execute(ProcessTask& task); 4256 virtual void execute(EnqueueTask& task); 4257 }; 4258 4259 // Gang task for possibly parallel reference processing 4260 4261 class G1STWRefProcTaskProxy: public AbstractGangTask { 4262 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 4263 ProcessTask& _proc_task; 4264 G1CollectedHeap* _g1h; 4265 G1ParScanThreadStateSet* _pss; 4266 RefToScanQueueSet* _task_queues; 4267 ParallelTaskTerminator* _terminator; 4268 4269 public: 4270 G1STWRefProcTaskProxy(ProcessTask& proc_task, 4271 G1CollectedHeap* g1h, 4272 G1ParScanThreadStateSet* per_thread_states, 4273 RefToScanQueueSet *task_queues, 4274 ParallelTaskTerminator* terminator) : 4275 AbstractGangTask("Process reference objects in parallel"), 4276 _proc_task(proc_task), 4277 _g1h(g1h), 4278 _pss(per_thread_states), 4279 _task_queues(task_queues), 4280 _terminator(terminator) 4281 {} 4282 4283 virtual void work(uint worker_id) { 4284 // The reference processing task executed by a single worker. 4285 ResourceMark rm; 4286 HandleMark hm; 4287 4288 G1STWIsAliveClosure is_alive(_g1h); 4289 4290 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4291 pss->set_ref_processor(NULL); 4292 4293 // Keep alive closure. 4294 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 4295 4296 // Complete GC closure 4297 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator); 4298 4299 // Call the reference processing task's work routine. 4300 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 4301 4302 // Note we cannot assert that the refs array is empty here as not all 4303 // of the processing tasks (specifically phase2 - pp2_work) execute 4304 // the complete_gc closure (which ordinarily would drain the queue) so 4305 // the queue may not be empty. 4306 } 4307 }; 4308 4309 // Driver routine for parallel reference processing. 4310 // Creates an instance of the ref processing gang 4311 // task and has the worker threads execute it. 4312 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 4313 assert(_workers != NULL, "Need parallel worker threads."); 4314 4315 ParallelTaskTerminator terminator(_active_workers, _queues); 4316 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 4317 4318 _workers->run_task(&proc_task_proxy); 4319 } 4320 4321 // Gang task for parallel reference enqueueing. 4322 4323 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 4324 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 4325 EnqueueTask& _enq_task; 4326 4327 public: 4328 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 4329 AbstractGangTask("Enqueue reference objects in parallel"), 4330 _enq_task(enq_task) 4331 { } 4332 4333 virtual void work(uint worker_id) { 4334 _enq_task.work(worker_id); 4335 } 4336 }; 4337 4338 // Driver routine for parallel reference enqueueing. 4339 // Creates an instance of the ref enqueueing gang 4340 // task and has the worker threads execute it. 4341 4342 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 4343 assert(_workers != NULL, "Need parallel worker threads."); 4344 4345 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 4346 4347 _workers->run_task(&enq_task_proxy); 4348 } 4349 4350 // End of weak reference support closures 4351 4352 // Abstract task used to preserve (i.e. copy) any referent objects 4353 // that are in the collection set and are pointed to by reference 4354 // objects discovered by the CM ref processor. 4355 4356 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 4357 protected: 4358 G1CollectedHeap* _g1h; 4359 G1ParScanThreadStateSet* _pss; 4360 RefToScanQueueSet* _queues; 4361 ParallelTaskTerminator _terminator; 4362 uint _n_workers; 4363 4364 public: 4365 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) : 4366 AbstractGangTask("ParPreserveCMReferents"), 4367 _g1h(g1h), 4368 _pss(per_thread_states), 4369 _queues(task_queues), 4370 _terminator(workers, _queues), 4371 _n_workers(workers) 4372 { 4373 g1h->ref_processor_cm()->set_active_mt_degree(workers); 4374 } 4375 4376 void work(uint worker_id) { 4377 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id); 4378 4379 ResourceMark rm; 4380 HandleMark hm; 4381 4382 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4383 pss->set_ref_processor(NULL); 4384 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 4385 4386 // Is alive closure 4387 G1AlwaysAliveClosure always_alive(_g1h); 4388 4389 // Copying keep alive closure. Applied to referent objects that need 4390 // to be copied. 4391 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 4392 4393 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 4394 4395 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 4396 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 4397 4398 // limit is set using max_num_q() - which was set using ParallelGCThreads. 4399 // So this must be true - but assert just in case someone decides to 4400 // change the worker ids. 4401 assert(worker_id < limit, "sanity"); 4402 assert(!rp->discovery_is_atomic(), "check this code"); 4403 4404 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 4405 for (uint idx = worker_id; idx < limit; idx += stride) { 4406 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 4407 4408 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 4409 while (iter.has_next()) { 4410 // Since discovery is not atomic for the CM ref processor, we 4411 // can see some null referent objects. 4412 iter.load_ptrs(DEBUG_ONLY(true)); 4413 oop ref = iter.obj(); 4414 4415 // This will filter nulls. 4416 if (iter.is_referent_alive()) { 4417 iter.make_referent_alive(); 4418 } 4419 iter.move_to_next(); 4420 } 4421 } 4422 4423 // Drain the queue - which may cause stealing 4424 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator); 4425 drain_queue.do_void(); 4426 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 4427 assert(pss->queue_is_empty(), "should be"); 4428 } 4429 }; 4430 4431 void G1CollectedHeap::process_weak_jni_handles() { 4432 double ref_proc_start = os::elapsedTime(); 4433 4434 G1STWIsAliveClosure is_alive(this); 4435 G1KeepAliveClosure keep_alive(this); 4436 JNIHandles::weak_oops_do(&is_alive, &keep_alive); 4437 4438 double ref_proc_time = os::elapsedTime() - ref_proc_start; 4439 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 4440 } 4441 4442 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) { 4443 double preserve_cm_referents_start = os::elapsedTime(); 4444 // Any reference objects, in the collection set, that were 'discovered' 4445 // by the CM ref processor should have already been copied (either by 4446 // applying the external root copy closure to the discovered lists, or 4447 // by following an RSet entry). 4448 // 4449 // But some of the referents, that are in the collection set, that these 4450 // reference objects point to may not have been copied: the STW ref 4451 // processor would have seen that the reference object had already 4452 // been 'discovered' and would have skipped discovering the reference, 4453 // but would not have treated the reference object as a regular oop. 4454 // As a result the copy closure would not have been applied to the 4455 // referent object. 4456 // 4457 // We need to explicitly copy these referent objects - the references 4458 // will be processed at the end of remarking. 4459 // 4460 // We also need to do this copying before we process the reference 4461 // objects discovered by the STW ref processor in case one of these 4462 // referents points to another object which is also referenced by an 4463 // object discovered by the STW ref processor. 4464 4465 uint no_of_gc_workers = workers()->active_workers(); 4466 4467 G1ParPreserveCMReferentsTask keep_cm_referents(this, 4468 per_thread_states, 4469 no_of_gc_workers, 4470 _task_queues); 4471 workers()->run_task(&keep_cm_referents); 4472 4473 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms((os::elapsedTime() - preserve_cm_referents_start) * 1000.0); 4474 } 4475 4476 // Weak Reference processing during an evacuation pause (part 1). 4477 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 4478 double ref_proc_start = os::elapsedTime(); 4479 4480 ReferenceProcessor* rp = _ref_processor_stw; 4481 assert(rp->discovery_enabled(), "should have been enabled"); 4482 4483 // Closure to test whether a referent is alive. 4484 G1STWIsAliveClosure is_alive(this); 4485 4486 // Even when parallel reference processing is enabled, the processing 4487 // of JNI refs is serial and performed serially by the current thread 4488 // rather than by a worker. The following PSS will be used for processing 4489 // JNI refs. 4490 4491 // Use only a single queue for this PSS. 4492 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 4493 pss->set_ref_processor(NULL); 4494 assert(pss->queue_is_empty(), "pre-condition"); 4495 4496 // Keep alive closure. 4497 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss); 4498 4499 // Serial Complete GC closure 4500 G1STWDrainQueueClosure drain_queue(this, pss); 4501 4502 // Setup the soft refs policy... 4503 rp->setup_policy(false); 4504 4505 ReferenceProcessorStats stats; 4506 if (!rp->processing_is_mt()) { 4507 // Serial reference processing... 4508 stats = rp->process_discovered_references(&is_alive, 4509 &keep_alive, 4510 &drain_queue, 4511 NULL, 4512 _gc_timer_stw); 4513 } else { 4514 uint no_of_gc_workers = workers()->active_workers(); 4515 4516 // Parallel reference processing 4517 assert(no_of_gc_workers <= rp->max_num_q(), 4518 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 4519 no_of_gc_workers, rp->max_num_q()); 4520 4521 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers); 4522 stats = rp->process_discovered_references(&is_alive, 4523 &keep_alive, 4524 &drain_queue, 4525 &par_task_executor, 4526 _gc_timer_stw); 4527 } 4528 4529 _gc_tracer_stw->report_gc_reference_stats(stats); 4530 4531 // We have completed copying any necessary live referent objects. 4532 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 4533 4534 double ref_proc_time = os::elapsedTime() - ref_proc_start; 4535 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 4536 } 4537 4538 // Weak Reference processing during an evacuation pause (part 2). 4539 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 4540 double ref_enq_start = os::elapsedTime(); 4541 4542 ReferenceProcessor* rp = _ref_processor_stw; 4543 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 4544 4545 // Now enqueue any remaining on the discovered lists on to 4546 // the pending list. 4547 if (!rp->processing_is_mt()) { 4548 // Serial reference processing... 4549 rp->enqueue_discovered_references(); 4550 } else { 4551 // Parallel reference enqueueing 4552 4553 uint n_workers = workers()->active_workers(); 4554 4555 assert(n_workers <= rp->max_num_q(), 4556 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 4557 n_workers, rp->max_num_q()); 4558 4559 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers); 4560 rp->enqueue_discovered_references(&par_task_executor); 4561 } 4562 4563 rp->verify_no_references_recorded(); 4564 assert(!rp->discovery_enabled(), "should have been disabled"); 4565 4566 // FIXME 4567 // CM's reference processing also cleans up the string and symbol tables. 4568 // Should we do that here also? We could, but it is a serial operation 4569 // and could significantly increase the pause time. 4570 4571 double ref_enq_time = os::elapsedTime() - ref_enq_start; 4572 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 4573 } 4574 4575 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 4576 double merge_pss_time_start = os::elapsedTime(); 4577 per_thread_states->flush(); 4578 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 4579 } 4580 4581 void G1CollectedHeap::pre_evacuate_collection_set() { 4582 _expand_heap_after_alloc_failure = true; 4583 _evacuation_failed = false; 4584 4585 // Disable the hot card cache. 4586 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 4587 hot_card_cache->reset_hot_cache_claimed_index(); 4588 hot_card_cache->set_use_cache(false); 4589 4590 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 4591 } 4592 4593 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 4594 // Should G1EvacuationFailureALot be in effect for this GC? 4595 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 4596 4597 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 4598 double start_par_time_sec = os::elapsedTime(); 4599 double end_par_time_sec; 4600 4601 { 4602 const uint n_workers = workers()->active_workers(); 4603 G1RootProcessor root_processor(this, n_workers); 4604 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 4605 // InitialMark needs claim bits to keep track of the marked-through CLDs. 4606 if (collector_state()->during_initial_mark_pause()) { 4607 ClassLoaderDataGraph::clear_claimed_marks(); 4608 } 4609 4610 print_termination_stats_hdr(); 4611 4612 workers()->run_task(&g1_par_task); 4613 end_par_time_sec = os::elapsedTime(); 4614 4615 // Closing the inner scope will execute the destructor 4616 // for the G1RootProcessor object. We record the current 4617 // elapsed time before closing the scope so that time 4618 // taken for the destructor is NOT included in the 4619 // reported parallel time. 4620 } 4621 4622 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 4623 4624 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 4625 phase_times->record_par_time(par_time_ms); 4626 4627 double code_root_fixup_time_ms = 4628 (os::elapsedTime() - end_par_time_sec) * 1000.0; 4629 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 4630 } 4631 4632 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 4633 // Process any discovered reference objects - we have 4634 // to do this _before_ we retire the GC alloc regions 4635 // as we may have to copy some 'reachable' referent 4636 // objects (and their reachable sub-graphs) that were 4637 // not copied during the pause. 4638 if (g1_policy()->should_process_references()) { 4639 preserve_cm_referents(per_thread_states); 4640 process_discovered_references(per_thread_states); 4641 } else { 4642 ref_processor_stw()->verify_no_references_recorded(); 4643 process_weak_jni_handles(); 4644 } 4645 4646 if (G1StringDedup::is_enabled()) { 4647 double fixup_start = os::elapsedTime(); 4648 4649 G1STWIsAliveClosure is_alive(this); 4650 G1KeepAliveClosure keep_alive(this); 4651 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times()); 4652 4653 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 4654 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms); 4655 } 4656 4657 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 4658 4659 if (evacuation_failed()) { 4660 restore_after_evac_failure(); 4661 4662 // Reset the G1EvacuationFailureALot counters and flags 4663 // Note: the values are reset only when an actual 4664 // evacuation failure occurs. 4665 NOT_PRODUCT(reset_evacuation_should_fail();) 4666 } 4667 4668 // Enqueue any remaining references remaining on the STW 4669 // reference processor's discovered lists. We need to do 4670 // this after the card table is cleaned (and verified) as 4671 // the act of enqueueing entries on to the pending list 4672 // will log these updates (and dirty their associated 4673 // cards). We need these updates logged to update any 4674 // RSets. 4675 if (g1_policy()->should_process_references()) { 4676 enqueue_discovered_references(per_thread_states); 4677 } else { 4678 g1_policy()->phase_times()->record_ref_enq_time(0); 4679 } 4680 4681 _allocator->release_gc_alloc_regions(evacuation_info); 4682 4683 merge_per_thread_state_info(per_thread_states); 4684 4685 // Reset and re-enable the hot card cache. 4686 // Note the counts for the cards in the regions in the 4687 // collection set are reset when the collection set is freed. 4688 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 4689 hot_card_cache->reset_hot_cache(); 4690 hot_card_cache->set_use_cache(true); 4691 4692 purge_code_root_memory(); 4693 4694 redirty_logged_cards(); 4695 #if defined(COMPILER2) || INCLUDE_JVMCI 4696 DerivedPointerTable::update_pointers(); 4697 #endif 4698 } 4699 4700 void G1CollectedHeap::record_obj_copy_mem_stats() { 4701 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 4702 4703 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 4704 create_g1_evac_summary(&_old_evac_stats)); 4705 } 4706 4707 void G1CollectedHeap::free_region(HeapRegion* hr, 4708 FreeRegionList* free_list, 4709 bool par, 4710 bool locked) { 4711 assert(!hr->is_free(), "the region should not be free"); 4712 assert(!hr->is_empty(), "the region should not be empty"); 4713 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 4714 assert(free_list != NULL, "pre-condition"); 4715 4716 if (G1VerifyBitmaps) { 4717 MemRegion mr(hr->bottom(), hr->end()); 4718 concurrent_mark()->clearRangePrevBitmap(mr); 4719 } 4720 4721 // Clear the card counts for this region. 4722 // Note: we only need to do this if the region is not young 4723 // (since we don't refine cards in young regions). 4724 if (!hr->is_young()) { 4725 _cg1r->hot_card_cache()->reset_card_counts(hr); 4726 } 4727 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 4728 free_list->add_ordered(hr); 4729 } 4730 4731 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4732 FreeRegionList* free_list, 4733 bool par) { 4734 assert(hr->is_humongous(), "this is only for humongous regions"); 4735 assert(free_list != NULL, "pre-condition"); 4736 hr->clear_humongous(); 4737 free_region(hr, free_list, par); 4738 } 4739 4740 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 4741 const uint humongous_regions_removed) { 4742 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 4743 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4744 _old_set.bulk_remove(old_regions_removed); 4745 _humongous_set.bulk_remove(humongous_regions_removed); 4746 } 4747 4748 } 4749 4750 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4751 assert(list != NULL, "list can't be null"); 4752 if (!list->is_empty()) { 4753 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4754 _hrm.insert_list_into_free_list(list); 4755 } 4756 } 4757 4758 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4759 decrease_used(bytes); 4760 } 4761 4762 class G1ParCleanupCTTask : public AbstractGangTask { 4763 G1SATBCardTableModRefBS* _ct_bs; 4764 G1CollectedHeap* _g1h; 4765 HeapRegion* volatile _su_head; 4766 public: 4767 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 4768 G1CollectedHeap* g1h) : 4769 AbstractGangTask("G1 Par Cleanup CT Task"), 4770 _ct_bs(ct_bs), _g1h(g1h) { } 4771 4772 void work(uint worker_id) { 4773 HeapRegion* r; 4774 while (r = _g1h->pop_dirty_cards_region()) { 4775 clear_cards(r); 4776 } 4777 } 4778 4779 void clear_cards(HeapRegion* r) { 4780 // Cards of the survivors should have already been dirtied. 4781 if (!r->is_survivor()) { 4782 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 4783 } 4784 } 4785 }; 4786 4787 class G1ParScrubRemSetTask: public AbstractGangTask { 4788 protected: 4789 G1RemSet* _g1rs; 4790 BitMap* _region_bm; 4791 BitMap* _card_bm; 4792 HeapRegionClaimer _hrclaimer; 4793 4794 public: 4795 G1ParScrubRemSetTask(G1RemSet* g1_rs, BitMap* region_bm, BitMap* card_bm, uint num_workers) : 4796 AbstractGangTask("G1 ScrubRS"), 4797 _g1rs(g1_rs), 4798 _region_bm(region_bm), 4799 _card_bm(card_bm), 4800 _hrclaimer(num_workers) { 4801 } 4802 4803 void work(uint worker_id) { 4804 _g1rs->scrub(_region_bm, _card_bm, worker_id, &_hrclaimer); 4805 } 4806 }; 4807 4808 void G1CollectedHeap::scrub_rem_set(BitMap* region_bm, BitMap* card_bm) { 4809 uint num_workers = workers()->active_workers(); 4810 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), region_bm, card_bm, num_workers); 4811 workers()->run_task(&g1_par_scrub_rs_task); 4812 } 4813 4814 void G1CollectedHeap::cleanUpCardTable() { 4815 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 4816 double start = os::elapsedTime(); 4817 4818 { 4819 // Iterate over the dirty cards region list. 4820 G1ParCleanupCTTask cleanup_task(ct_bs, this); 4821 4822 workers()->run_task(&cleanup_task); 4823 #ifndef PRODUCT 4824 _verifier->verify_card_table_cleanup(); 4825 #endif 4826 } 4827 4828 double elapsed = os::elapsedTime() - start; 4829 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 4830 } 4831 4832 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4833 size_t pre_used = 0; 4834 FreeRegionList local_free_list("Local List for CSet Freeing"); 4835 4836 double young_time_ms = 0.0; 4837 double non_young_time_ms = 0.0; 4838 4839 // Since the collection set is a superset of the the young list, 4840 // all we need to do to clear the young list is clear its 4841 // head and length, and unlink any young regions in the code below 4842 _young_list->clear(); 4843 4844 G1CollectorPolicy* policy = g1_policy(); 4845 4846 double start_sec = os::elapsedTime(); 4847 bool non_young = true; 4848 4849 HeapRegion* cur = cs_head; 4850 int age_bound = -1; 4851 size_t rs_lengths = 0; 4852 4853 while (cur != NULL) { 4854 assert(!is_on_master_free_list(cur), "sanity"); 4855 if (non_young) { 4856 if (cur->is_young()) { 4857 double end_sec = os::elapsedTime(); 4858 double elapsed_ms = (end_sec - start_sec) * 1000.0; 4859 non_young_time_ms += elapsed_ms; 4860 4861 start_sec = os::elapsedTime(); 4862 non_young = false; 4863 } 4864 } else { 4865 if (!cur->is_young()) { 4866 double end_sec = os::elapsedTime(); 4867 double elapsed_ms = (end_sec - start_sec) * 1000.0; 4868 young_time_ms += elapsed_ms; 4869 4870 start_sec = os::elapsedTime(); 4871 non_young = true; 4872 } 4873 } 4874 4875 rs_lengths += cur->rem_set()->occupied_locked(); 4876 4877 HeapRegion* next = cur->next_in_collection_set(); 4878 assert(cur->in_collection_set(), "bad CS"); 4879 cur->set_next_in_collection_set(NULL); 4880 clear_in_cset(cur); 4881 4882 if (cur->is_young()) { 4883 int index = cur->young_index_in_cset(); 4884 assert(index != -1, "invariant"); 4885 assert((uint) index < collection_set()->young_region_length(), "invariant"); 4886 size_t words_survived = surviving_young_words[index]; 4887 cur->record_surv_words_in_group(words_survived); 4888 4889 // At this point the we have 'popped' cur from the collection set 4890 // (linked via next_in_collection_set()) but it is still in the 4891 // young list (linked via next_young_region()). Clear the 4892 // _next_young_region field. 4893 cur->set_next_young_region(NULL); 4894 } else { 4895 int index = cur->young_index_in_cset(); 4896 assert(index == -1, "invariant"); 4897 } 4898 4899 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 4900 (!cur->is_young() && cur->young_index_in_cset() == -1), 4901 "invariant" ); 4902 4903 if (!cur->evacuation_failed()) { 4904 MemRegion used_mr = cur->used_region(); 4905 4906 // And the region is empty. 4907 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 4908 pre_used += cur->used(); 4909 free_region(cur, &local_free_list, false /* par */, true /* locked */); 4910 } else { 4911 cur->uninstall_surv_rate_group(); 4912 if (cur->is_young()) { 4913 cur->set_young_index_in_cset(-1); 4914 } 4915 cur->set_evacuation_failed(false); 4916 // When moving a young gen region to old gen, we "allocate" that whole region 4917 // there. This is in addition to any already evacuated objects. Notify the 4918 // policy about that. 4919 // Old gen regions do not cause an additional allocation: both the objects 4920 // still in the region and the ones already moved are accounted for elsewhere. 4921 if (cur->is_young()) { 4922 policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes); 4923 } 4924 // The region is now considered to be old. 4925 cur->set_old(); 4926 // Do some allocation statistics accounting. Regions that failed evacuation 4927 // are always made old, so there is no need to update anything in the young 4928 // gen statistics, but we need to update old gen statistics. 4929 size_t used_words = cur->marked_bytes() / HeapWordSize; 4930 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words); 4931 _old_set.add(cur); 4932 evacuation_info.increment_collectionset_used_after(cur->used()); 4933 } 4934 cur = next; 4935 } 4936 4937 evacuation_info.set_regions_freed(local_free_list.length()); 4938 policy->record_max_rs_lengths(rs_lengths); 4939 policy->cset_regions_freed(); 4940 4941 double end_sec = os::elapsedTime(); 4942 double elapsed_ms = (end_sec - start_sec) * 1000.0; 4943 4944 if (non_young) { 4945 non_young_time_ms += elapsed_ms; 4946 } else { 4947 young_time_ms += elapsed_ms; 4948 } 4949 4950 prepend_to_freelist(&local_free_list); 4951 decrement_summary_bytes(pre_used); 4952 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 4953 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 4954 } 4955 4956 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4957 private: 4958 FreeRegionList* _free_region_list; 4959 HeapRegionSet* _proxy_set; 4960 uint _humongous_regions_removed; 4961 size_t _freed_bytes; 4962 public: 4963 4964 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4965 _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) { 4966 } 4967 4968 virtual bool doHeapRegion(HeapRegion* r) { 4969 if (!r->is_starts_humongous()) { 4970 return false; 4971 } 4972 4973 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4974 4975 oop obj = (oop)r->bottom(); 4976 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 4977 4978 // The following checks whether the humongous object is live are sufficient. 4979 // The main additional check (in addition to having a reference from the roots 4980 // or the young gen) is whether the humongous object has a remembered set entry. 4981 // 4982 // A humongous object cannot be live if there is no remembered set for it 4983 // because: 4984 // - there can be no references from within humongous starts regions referencing 4985 // the object because we never allocate other objects into them. 4986 // (I.e. there are no intra-region references that may be missed by the 4987 // remembered set) 4988 // - as soon there is a remembered set entry to the humongous starts region 4989 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4990 // until the end of a concurrent mark. 4991 // 4992 // It is not required to check whether the object has been found dead by marking 4993 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4994 // all objects allocated during that time are considered live. 4995 // SATB marking is even more conservative than the remembered set. 4996 // So if at this point in the collection there is no remembered set entry, 4997 // nobody has a reference to it. 4998 // At the start of collection we flush all refinement logs, and remembered sets 4999 // are completely up-to-date wrt to references to the humongous object. 5000 // 5001 // Other implementation considerations: 5002 // - never consider object arrays at this time because they would pose 5003 // considerable effort for cleaning up the the remembered sets. This is 5004 // required because stale remembered sets might reference locations that 5005 // are currently allocated into. 5006 uint region_idx = r->hrm_index(); 5007 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 5008 !r->rem_set()->is_empty()) { 5009 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", 5010 region_idx, 5011 (size_t)obj->size() * HeapWordSize, 5012 p2i(r->bottom()), 5013 r->rem_set()->occupied(), 5014 r->rem_set()->strong_code_roots_list_length(), 5015 next_bitmap->isMarked(r->bottom()), 5016 g1h->is_humongous_reclaim_candidate(region_idx), 5017 obj->is_typeArray() 5018 ); 5019 return false; 5020 } 5021 5022 guarantee(obj->is_typeArray(), 5023 "Only eagerly reclaiming type arrays is supported, but the object " 5024 PTR_FORMAT " is not.", p2i(r->bottom())); 5025 5026 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", 5027 region_idx, 5028 (size_t)obj->size() * HeapWordSize, 5029 p2i(r->bottom()), 5030 r->rem_set()->occupied(), 5031 r->rem_set()->strong_code_roots_list_length(), 5032 next_bitmap->isMarked(r->bottom()), 5033 g1h->is_humongous_reclaim_candidate(region_idx), 5034 obj->is_typeArray() 5035 ); 5036 5037 // Need to clear mark bit of the humongous object if already set. 5038 if (next_bitmap->isMarked(r->bottom())) { 5039 next_bitmap->clear(r->bottom()); 5040 } 5041 do { 5042 HeapRegion* next = g1h->next_region_in_humongous(r); 5043 _freed_bytes += r->used(); 5044 r->set_containing_set(NULL); 5045 _humongous_regions_removed++; 5046 g1h->free_humongous_region(r, _free_region_list, false); 5047 r = next; 5048 } while (r != NULL); 5049 5050 return false; 5051 } 5052 5053 uint humongous_free_count() { 5054 return _humongous_regions_removed; 5055 } 5056 5057 size_t bytes_freed() const { 5058 return _freed_bytes; 5059 } 5060 }; 5061 5062 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 5063 assert_at_safepoint(true); 5064 5065 if (!G1EagerReclaimHumongousObjects || 5066 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 5067 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 5068 return; 5069 } 5070 5071 double start_time = os::elapsedTime(); 5072 5073 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 5074 5075 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 5076 heap_region_iterate(&cl); 5077 5078 remove_from_old_sets(0, cl.humongous_free_count()); 5079 5080 G1HRPrinter* hrp = hr_printer(); 5081 if (hrp->is_active()) { 5082 FreeRegionListIterator iter(&local_cleanup_list); 5083 while (iter.more_available()) { 5084 HeapRegion* hr = iter.get_next(); 5085 hrp->cleanup(hr); 5086 } 5087 } 5088 5089 prepend_to_freelist(&local_cleanup_list); 5090 decrement_summary_bytes(cl.bytes_freed()); 5091 5092 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 5093 cl.humongous_free_count()); 5094 } 5095 5096 // This routine is similar to the above but does not record 5097 // any policy statistics or update free lists; we are abandoning 5098 // the current incremental collection set in preparation of a 5099 // full collection. After the full GC we will start to build up 5100 // the incremental collection set again. 5101 // This is only called when we're doing a full collection 5102 // and is immediately followed by the tearing down of the young list. 5103 5104 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 5105 HeapRegion* cur = cs_head; 5106 5107 while (cur != NULL) { 5108 HeapRegion* next = cur->next_in_collection_set(); 5109 assert(cur->in_collection_set(), "bad CS"); 5110 cur->set_next_in_collection_set(NULL); 5111 clear_in_cset(cur); 5112 cur->set_young_index_in_cset(-1); 5113 cur = next; 5114 } 5115 } 5116 5117 void G1CollectedHeap::set_free_regions_coming() { 5118 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming"); 5119 5120 assert(!free_regions_coming(), "pre-condition"); 5121 _free_regions_coming = true; 5122 } 5123 5124 void G1CollectedHeap::reset_free_regions_coming() { 5125 assert(free_regions_coming(), "pre-condition"); 5126 5127 { 5128 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5129 _free_regions_coming = false; 5130 SecondaryFreeList_lock->notify_all(); 5131 } 5132 5133 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming"); 5134 } 5135 5136 void G1CollectedHeap::wait_while_free_regions_coming() { 5137 // Most of the time we won't have to wait, so let's do a quick test 5138 // first before we take the lock. 5139 if (!free_regions_coming()) { 5140 return; 5141 } 5142 5143 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions"); 5144 5145 { 5146 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5147 while (free_regions_coming()) { 5148 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 5149 } 5150 } 5151 5152 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions"); 5153 } 5154 5155 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 5156 return _allocator->is_retained_old_region(hr); 5157 } 5158 5159 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 5160 _young_list->push_region(hr); 5161 } 5162 5163 class NoYoungRegionsClosure: public HeapRegionClosure { 5164 private: 5165 bool _success; 5166 public: 5167 NoYoungRegionsClosure() : _success(true) { } 5168 bool doHeapRegion(HeapRegion* r) { 5169 if (r->is_young()) { 5170 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 5171 p2i(r->bottom()), p2i(r->end())); 5172 _success = false; 5173 } 5174 return false; 5175 } 5176 bool success() { return _success; } 5177 }; 5178 5179 bool G1CollectedHeap::check_young_list_empty(bool check_heap) { 5180 bool ret = _young_list->check_list_empty(); 5181 5182 if (check_heap) { 5183 NoYoungRegionsClosure closure; 5184 heap_region_iterate(&closure); 5185 ret = ret && closure.success(); 5186 } 5187 5188 return ret; 5189 } 5190 5191 class TearDownRegionSetsClosure : public HeapRegionClosure { 5192 private: 5193 HeapRegionSet *_old_set; 5194 5195 public: 5196 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 5197 5198 bool doHeapRegion(HeapRegion* r) { 5199 if (r->is_old()) { 5200 _old_set->remove(r); 5201 } else { 5202 // We ignore free regions, we'll empty the free list afterwards. 5203 // We ignore young regions, we'll empty the young list afterwards. 5204 // We ignore humongous regions, we're not tearing down the 5205 // humongous regions set. 5206 assert(r->is_free() || r->is_young() || r->is_humongous(), 5207 "it cannot be another type"); 5208 } 5209 return false; 5210 } 5211 5212 ~TearDownRegionSetsClosure() { 5213 assert(_old_set->is_empty(), "post-condition"); 5214 } 5215 }; 5216 5217 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 5218 assert_at_safepoint(true /* should_be_vm_thread */); 5219 5220 if (!free_list_only) { 5221 TearDownRegionSetsClosure cl(&_old_set); 5222 heap_region_iterate(&cl); 5223 5224 // Note that emptying the _young_list is postponed and instead done as 5225 // the first step when rebuilding the regions sets again. The reason for 5226 // this is that during a full GC string deduplication needs to know if 5227 // a collected region was young or old when the full GC was initiated. 5228 } 5229 _hrm.remove_all_free_regions(); 5230 } 5231 5232 void G1CollectedHeap::increase_used(size_t bytes) { 5233 _summary_bytes_used += bytes; 5234 } 5235 5236 void G1CollectedHeap::decrease_used(size_t bytes) { 5237 assert(_summary_bytes_used >= bytes, 5238 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 5239 _summary_bytes_used, bytes); 5240 _summary_bytes_used -= bytes; 5241 } 5242 5243 void G1CollectedHeap::set_used(size_t bytes) { 5244 _summary_bytes_used = bytes; 5245 } 5246 5247 class RebuildRegionSetsClosure : public HeapRegionClosure { 5248 private: 5249 bool _free_list_only; 5250 HeapRegionSet* _old_set; 5251 HeapRegionManager* _hrm; 5252 size_t _total_used; 5253 5254 public: 5255 RebuildRegionSetsClosure(bool free_list_only, 5256 HeapRegionSet* old_set, HeapRegionManager* hrm) : 5257 _free_list_only(free_list_only), 5258 _old_set(old_set), _hrm(hrm), _total_used(0) { 5259 assert(_hrm->num_free_regions() == 0, "pre-condition"); 5260 if (!free_list_only) { 5261 assert(_old_set->is_empty(), "pre-condition"); 5262 } 5263 } 5264 5265 bool doHeapRegion(HeapRegion* r) { 5266 if (r->is_empty()) { 5267 // Add free regions to the free list 5268 r->set_free(); 5269 r->set_allocation_context(AllocationContext::system()); 5270 _hrm->insert_into_free_list(r); 5271 } else if (!_free_list_only) { 5272 assert(!r->is_young(), "we should not come across young regions"); 5273 5274 if (r->is_humongous()) { 5275 // We ignore humongous regions. We left the humongous set unchanged. 5276 } else { 5277 // Objects that were compacted would have ended up on regions 5278 // that were previously old or free. Archive regions (which are 5279 // old) will not have been touched. 5280 assert(r->is_free() || r->is_old(), "invariant"); 5281 // We now consider them old, so register as such. Leave 5282 // archive regions set that way, however, while still adding 5283 // them to the old set. 5284 if (!r->is_archive()) { 5285 r->set_old(); 5286 } 5287 _old_set->add(r); 5288 } 5289 _total_used += r->used(); 5290 } 5291 5292 return false; 5293 } 5294 5295 size_t total_used() { 5296 return _total_used; 5297 } 5298 }; 5299 5300 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 5301 assert_at_safepoint(true /* should_be_vm_thread */); 5302 5303 if (!free_list_only) { 5304 _young_list->empty_list(); 5305 } 5306 5307 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 5308 heap_region_iterate(&cl); 5309 5310 if (!free_list_only) { 5311 set_used(cl.total_used()); 5312 if (_archive_allocator != NULL) { 5313 _archive_allocator->clear_used(); 5314 } 5315 } 5316 assert(used_unlocked() == recalculate_used(), 5317 "inconsistent used_unlocked(), " 5318 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 5319 used_unlocked(), recalculate_used()); 5320 } 5321 5322 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 5323 _refine_cte_cl->set_concurrent(concurrent); 5324 } 5325 5326 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 5327 HeapRegion* hr = heap_region_containing(p); 5328 return hr->is_in(p); 5329 } 5330 5331 // Methods for the mutator alloc region 5332 5333 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 5334 bool force) { 5335 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 5336 assert(!force || g1_policy()->can_expand_young_list(), 5337 "if force is true we should be able to expand the young list"); 5338 bool young_list_full = g1_policy()->is_young_list_full(); 5339 if (force || !young_list_full) { 5340 HeapRegion* new_alloc_region = new_region(word_size, 5341 false /* is_old */, 5342 false /* do_expand */); 5343 if (new_alloc_region != NULL) { 5344 set_region_short_lived_locked(new_alloc_region); 5345 _hr_printer.alloc(new_alloc_region, young_list_full); 5346 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 5347 return new_alloc_region; 5348 } 5349 } 5350 return NULL; 5351 } 5352 5353 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 5354 size_t allocated_bytes) { 5355 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 5356 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 5357 5358 collection_set()->add_eden_region(alloc_region); 5359 increase_used(allocated_bytes); 5360 _hr_printer.retire(alloc_region); 5361 // We update the eden sizes here, when the region is retired, 5362 // instead of when it's allocated, since this is the point that its 5363 // used space has been recored in _summary_bytes_used. 5364 g1mm()->update_eden_size(); 5365 } 5366 5367 // Methods for the GC alloc regions 5368 5369 bool G1CollectedHeap::has_more_regions(InCSetState dest) { 5370 if (dest.is_old()) { 5371 return true; 5372 } else { 5373 return young_list()->survivor_length() < g1_policy()->max_survivor_regions(); 5374 } 5375 } 5376 5377 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) { 5378 assert(FreeList_lock->owned_by_self(), "pre-condition"); 5379 5380 if (!has_more_regions(dest)) { 5381 return NULL; 5382 } 5383 5384 const bool is_survivor = dest.is_young(); 5385 5386 HeapRegion* new_alloc_region = new_region(word_size, 5387 !is_survivor, 5388 true /* do_expand */); 5389 if (new_alloc_region != NULL) { 5390 // We really only need to do this for old regions given that we 5391 // should never scan survivors. But it doesn't hurt to do it 5392 // for survivors too. 5393 new_alloc_region->record_timestamp(); 5394 if (is_survivor) { 5395 new_alloc_region->set_survivor(); 5396 young_list()->add_survivor_region(new_alloc_region); 5397 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 5398 } else { 5399 new_alloc_region->set_old(); 5400 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 5401 } 5402 _hr_printer.alloc(new_alloc_region); 5403 bool during_im = collector_state()->during_initial_mark_pause(); 5404 new_alloc_region->note_start_of_copying(during_im); 5405 return new_alloc_region; 5406 } 5407 return NULL; 5408 } 5409 5410 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 5411 size_t allocated_bytes, 5412 InCSetState dest) { 5413 bool during_im = collector_state()->during_initial_mark_pause(); 5414 alloc_region->note_end_of_copying(during_im); 5415 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 5416 if (dest.is_old()) { 5417 _old_set.add(alloc_region); 5418 } 5419 _hr_printer.retire(alloc_region); 5420 } 5421 5422 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 5423 bool expanded = false; 5424 uint index = _hrm.find_highest_free(&expanded); 5425 5426 if (index != G1_NO_HRM_INDEX) { 5427 if (expanded) { 5428 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 5429 HeapRegion::GrainWords * HeapWordSize); 5430 } 5431 _hrm.allocate_free_regions_starting_at(index, 1); 5432 return region_at(index); 5433 } 5434 return NULL; 5435 } 5436 5437 // Optimized nmethod scanning 5438 5439 class RegisterNMethodOopClosure: public OopClosure { 5440 G1CollectedHeap* _g1h; 5441 nmethod* _nm; 5442 5443 template <class T> void do_oop_work(T* p) { 5444 T heap_oop = oopDesc::load_heap_oop(p); 5445 if (!oopDesc::is_null(heap_oop)) { 5446 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 5447 HeapRegion* hr = _g1h->heap_region_containing(obj); 5448 assert(!hr->is_continues_humongous(), 5449 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 5450 " starting at " HR_FORMAT, 5451 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 5452 5453 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 5454 hr->add_strong_code_root_locked(_nm); 5455 } 5456 } 5457 5458 public: 5459 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 5460 _g1h(g1h), _nm(nm) {} 5461 5462 void do_oop(oop* p) { do_oop_work(p); } 5463 void do_oop(narrowOop* p) { do_oop_work(p); } 5464 }; 5465 5466 class UnregisterNMethodOopClosure: public OopClosure { 5467 G1CollectedHeap* _g1h; 5468 nmethod* _nm; 5469 5470 template <class T> void do_oop_work(T* p) { 5471 T heap_oop = oopDesc::load_heap_oop(p); 5472 if (!oopDesc::is_null(heap_oop)) { 5473 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 5474 HeapRegion* hr = _g1h->heap_region_containing(obj); 5475 assert(!hr->is_continues_humongous(), 5476 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 5477 " starting at " HR_FORMAT, 5478 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 5479 5480 hr->remove_strong_code_root(_nm); 5481 } 5482 } 5483 5484 public: 5485 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 5486 _g1h(g1h), _nm(nm) {} 5487 5488 void do_oop(oop* p) { do_oop_work(p); } 5489 void do_oop(narrowOop* p) { do_oop_work(p); } 5490 }; 5491 5492 void G1CollectedHeap::register_nmethod(nmethod* nm) { 5493 CollectedHeap::register_nmethod(nm); 5494 5495 guarantee(nm != NULL, "sanity"); 5496 RegisterNMethodOopClosure reg_cl(this, nm); 5497 nm->oops_do(®_cl); 5498 } 5499 5500 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 5501 CollectedHeap::unregister_nmethod(nm); 5502 5503 guarantee(nm != NULL, "sanity"); 5504 UnregisterNMethodOopClosure reg_cl(this, nm); 5505 nm->oops_do(®_cl, true); 5506 } 5507 5508 void G1CollectedHeap::purge_code_root_memory() { 5509 double purge_start = os::elapsedTime(); 5510 G1CodeRootSet::purge(); 5511 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 5512 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 5513 } 5514 5515 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 5516 G1CollectedHeap* _g1h; 5517 5518 public: 5519 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 5520 _g1h(g1h) {} 5521 5522 void do_code_blob(CodeBlob* cb) { 5523 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 5524 if (nm == NULL) { 5525 return; 5526 } 5527 5528 if (ScavengeRootsInCode) { 5529 _g1h->register_nmethod(nm); 5530 } 5531 } 5532 }; 5533 5534 void G1CollectedHeap::rebuild_strong_code_roots() { 5535 RebuildStrongCodeRootClosure blob_cl(this); 5536 CodeCache::blobs_do(&blob_cl); 5537 }