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