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/g1HeapTransition.hpp" 43 #include "gc/g1/g1HeapVerifier.hpp" 44 #include "gc/g1/g1MarkSweep.hpp" 45 #include "gc/g1/g1OopClosures.inline.hpp" 46 #include "gc/g1/g1ParScanThreadState.inline.hpp" 47 #include "gc/g1/g1RegionToSpaceMapper.hpp" 48 #include "gc/g1/g1RemSet.inline.hpp" 49 #include "gc/g1/g1RootClosures.hpp" 50 #include "gc/g1/g1RootProcessor.hpp" 51 #include "gc/g1/g1StringDedup.hpp" 52 #include "gc/g1/g1YCTypes.hpp" 53 #include "gc/g1/heapRegion.inline.hpp" 54 #include "gc/g1/heapRegionRemSet.hpp" 55 #include "gc/g1/heapRegionSet.inline.hpp" 56 #include "gc/g1/suspendibleThreadSet.hpp" 57 #include "gc/g1/vm_operations_g1.hpp" 58 #include "gc/shared/gcHeapSummary.hpp" 59 #include "gc/shared/gcId.hpp" 60 #include "gc/shared/gcLocker.inline.hpp" 61 #include "gc/shared/gcTimer.hpp" 62 #include "gc/shared/gcTrace.hpp" 63 #include "gc/shared/gcTraceTime.inline.hpp" 64 #include "gc/shared/generationSpec.hpp" 65 #include "gc/shared/isGCActiveMark.hpp" 66 #include "gc/shared/referenceProcessor.inline.hpp" 67 #include "gc/shared/taskqueue.inline.hpp" 68 #include "logging/log.hpp" 69 #include "memory/allocation.hpp" 70 #include "memory/iterator.hpp" 71 #include "oops/oop.inline.hpp" 72 #include "runtime/atomic.inline.hpp" 73 #include "runtime/init.hpp" 74 #include "runtime/orderAccess.inline.hpp" 75 #include "runtime/vmThread.hpp" 76 #include "utilities/globalDefinitions.hpp" 77 #include "utilities/stack.inline.hpp" 78 79 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 80 81 // INVARIANTS/NOTES 82 // 83 // All allocation activity covered by the G1CollectedHeap interface is 84 // serialized by acquiring the HeapLock. This happens in mem_allocate 85 // and allocate_new_tlab, which are the "entry" points to the 86 // allocation code from the rest of the JVM. (Note that this does not 87 // apply to TLAB allocation, which is not part of this interface: it 88 // is done by clients of this interface.) 89 90 // Local to this file. 91 92 class RefineCardTableEntryClosure: public CardTableEntryClosure { 93 bool _concurrent; 94 public: 95 RefineCardTableEntryClosure() : _concurrent(true) { } 96 97 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 98 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 99 // This path is executed by the concurrent refine or mutator threads, 100 // concurrently, and so we do not care if card_ptr contains references 101 // that point into the collection set. 102 assert(!oops_into_cset, "should be"); 103 104 if (_concurrent && SuspendibleThreadSet::should_yield()) { 105 // Caller will actually yield. 106 return false; 107 } 108 // Otherwise, we finished successfully; return true. 109 return true; 110 } 111 112 void set_concurrent(bool b) { _concurrent = b; } 113 }; 114 115 116 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 117 private: 118 size_t _num_dirtied; 119 G1CollectedHeap* _g1h; 120 G1SATBCardTableLoggingModRefBS* _g1_bs; 121 122 HeapRegion* region_for_card(jbyte* card_ptr) const { 123 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr)); 124 } 125 126 bool will_become_free(HeapRegion* hr) const { 127 // A region will be freed by free_collection_set if the region is in the 128 // collection set and has not had an evacuation failure. 129 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 130 } 131 132 public: 133 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(), 134 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { } 135 136 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 137 HeapRegion* hr = region_for_card(card_ptr); 138 139 // Should only dirty cards in regions that won't be freed. 140 if (!will_become_free(hr)) { 141 *card_ptr = CardTableModRefBS::dirty_card_val(); 142 _num_dirtied++; 143 } 144 145 return true; 146 } 147 148 size_t num_dirtied() const { return _num_dirtied; } 149 }; 150 151 152 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 153 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 154 } 155 156 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 157 // The from card cache is not the memory that is actually committed. So we cannot 158 // take advantage of the zero_filled parameter. 159 reset_from_card_cache(start_idx, num_regions); 160 } 161 162 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 163 { 164 // Claim the right to put the region on the dirty cards region list 165 // by installing a self pointer. 166 HeapRegion* next = hr->get_next_dirty_cards_region(); 167 if (next == NULL) { 168 HeapRegion* res = (HeapRegion*) 169 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 170 NULL); 171 if (res == NULL) { 172 HeapRegion* head; 173 do { 174 // Put the region to the dirty cards region list. 175 head = _dirty_cards_region_list; 176 next = (HeapRegion*) 177 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 178 if (next == head) { 179 assert(hr->get_next_dirty_cards_region() == hr, 180 "hr->get_next_dirty_cards_region() != hr"); 181 if (next == NULL) { 182 // The last region in the list points to itself. 183 hr->set_next_dirty_cards_region(hr); 184 } else { 185 hr->set_next_dirty_cards_region(next); 186 } 187 } 188 } while (next != head); 189 } 190 } 191 } 192 193 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 194 { 195 HeapRegion* head; 196 HeapRegion* hr; 197 do { 198 head = _dirty_cards_region_list; 199 if (head == NULL) { 200 return NULL; 201 } 202 HeapRegion* new_head = head->get_next_dirty_cards_region(); 203 if (head == new_head) { 204 // The last region. 205 new_head = NULL; 206 } 207 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 208 head); 209 } while (hr != head); 210 assert(hr != NULL, "invariant"); 211 hr->set_next_dirty_cards_region(NULL); 212 return hr; 213 } 214 215 // Returns true if the reference points to an object that 216 // can move in an incremental collection. 217 bool G1CollectedHeap::is_scavengable(const void* p) { 218 HeapRegion* hr = heap_region_containing(p); 219 return !hr->is_pinned(); 220 } 221 222 // Private methods. 223 224 HeapRegion* 225 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 226 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 227 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 228 if (!_secondary_free_list.is_empty()) { 229 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 230 "secondary_free_list has %u entries", 231 _secondary_free_list.length()); 232 // It looks as if there are free regions available on the 233 // secondary_free_list. Let's move them to the free_list and try 234 // again to allocate from it. 235 append_secondary_free_list(); 236 237 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 238 "empty we should have moved at least one entry to the free_list"); 239 HeapRegion* res = _hrm.allocate_free_region(is_old); 240 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 241 "allocated " HR_FORMAT " from secondary_free_list", 242 HR_FORMAT_PARAMS(res)); 243 return res; 244 } 245 246 // Wait here until we get notified either when (a) there are no 247 // more free regions coming or (b) some regions have been moved on 248 // the secondary_free_list. 249 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 250 } 251 252 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 253 "could not allocate from secondary_free_list"); 254 return NULL; 255 } 256 257 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 258 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 259 "the only time we use this to allocate a humongous region is " 260 "when we are allocating a single humongous region"); 261 262 HeapRegion* res; 263 if (G1StressConcRegionFreeing) { 264 if (!_secondary_free_list.is_empty()) { 265 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 266 "forced to look at the secondary_free_list"); 267 res = new_region_try_secondary_free_list(is_old); 268 if (res != NULL) { 269 return res; 270 } 271 } 272 } 273 274 res = _hrm.allocate_free_region(is_old); 275 276 if (res == NULL) { 277 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 278 "res == NULL, trying the secondary_free_list"); 279 res = new_region_try_secondary_free_list(is_old); 280 } 281 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 282 // Currently, only attempts to allocate GC alloc regions set 283 // do_expand to true. So, we should only reach here during a 284 // safepoint. If this assumption changes we might have to 285 // reconsider the use of _expand_heap_after_alloc_failure. 286 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 287 288 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 289 word_size * HeapWordSize); 290 291 if (expand(word_size * HeapWordSize)) { 292 // Given that expand() succeeded in expanding the heap, and we 293 // always expand the heap by an amount aligned to the heap 294 // region size, the free list should in theory not be empty. 295 // In either case allocate_free_region() will check for NULL. 296 res = _hrm.allocate_free_region(is_old); 297 } else { 298 _expand_heap_after_alloc_failure = false; 299 } 300 } 301 return res; 302 } 303 304 HeapWord* 305 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 306 uint num_regions, 307 size_t word_size, 308 AllocationContext_t context) { 309 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 310 assert(is_humongous(word_size), "word_size should be humongous"); 311 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 312 313 // Index of last region in the series. 314 uint last = first + num_regions - 1; 315 316 // We need to initialize the region(s) we just discovered. This is 317 // a bit tricky given that it can happen concurrently with 318 // refinement threads refining cards on these regions and 319 // potentially wanting to refine the BOT as they are scanning 320 // those cards (this can happen shortly after a cleanup; see CR 321 // 6991377). So we have to set up the region(s) carefully and in 322 // a specific order. 323 324 // The word size sum of all the regions we will allocate. 325 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 326 assert(word_size <= word_size_sum, "sanity"); 327 328 // This will be the "starts humongous" region. 329 HeapRegion* first_hr = region_at(first); 330 // The header of the new object will be placed at the bottom of 331 // the first region. 332 HeapWord* new_obj = first_hr->bottom(); 333 // This will be the new top of the new object. 334 HeapWord* obj_top = new_obj + word_size; 335 336 // First, we need to zero the header of the space that we will be 337 // allocating. When we update top further down, some refinement 338 // threads might try to scan the region. By zeroing the header we 339 // ensure that any thread that will try to scan the region will 340 // come across the zero klass word and bail out. 341 // 342 // NOTE: It would not have been correct to have used 343 // CollectedHeap::fill_with_object() and make the space look like 344 // an int array. The thread that is doing the allocation will 345 // later update the object header to a potentially different array 346 // type and, for a very short period of time, the klass and length 347 // fields will be inconsistent. This could cause a refinement 348 // thread to calculate the object size incorrectly. 349 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 350 351 // How many words we use for filler objects. 352 size_t word_fill_size = word_size_sum - word_size; 353 354 // How many words memory we "waste" which cannot hold a filler object. 355 size_t words_not_fillable = 0; 356 357 if (word_fill_size >= min_fill_size()) { 358 fill_with_objects(obj_top, word_fill_size); 359 } else if (word_fill_size > 0) { 360 // We have space to fill, but we cannot fit an object there. 361 words_not_fillable = word_fill_size; 362 word_fill_size = 0; 363 } 364 365 // We will set up the first region as "starts humongous". This 366 // will also update the BOT covering all the regions to reflect 367 // that there is a single object that starts at the bottom of the 368 // first region. 369 first_hr->set_starts_humongous(obj_top, word_fill_size); 370 first_hr->set_allocation_context(context); 371 // Then, if there are any, we will set up the "continues 372 // humongous" regions. 373 HeapRegion* hr = NULL; 374 for (uint i = first + 1; i <= last; ++i) { 375 hr = region_at(i); 376 hr->set_continues_humongous(first_hr); 377 hr->set_allocation_context(context); 378 } 379 380 // Up to this point no concurrent thread would have been able to 381 // do any scanning on any region in this series. All the top 382 // fields still point to bottom, so the intersection between 383 // [bottom,top] and [card_start,card_end] will be empty. Before we 384 // update the top fields, we'll do a storestore to make sure that 385 // no thread sees the update to top before the zeroing of the 386 // object header and the BOT initialization. 387 OrderAccess::storestore(); 388 389 // Now, we will update the top fields of the "continues humongous" 390 // regions except the last one. 391 for (uint i = first; i < last; ++i) { 392 hr = region_at(i); 393 hr->set_top(hr->end()); 394 } 395 396 hr = region_at(last); 397 // If we cannot fit a filler object, we must set top to the end 398 // of the humongous object, otherwise we cannot iterate the heap 399 // and the BOT will not be complete. 400 hr->set_top(hr->end() - words_not_fillable); 401 402 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 403 "obj_top should be in last region"); 404 405 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 406 407 assert(words_not_fillable == 0 || 408 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 409 "Miscalculation in humongous allocation"); 410 411 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 412 413 for (uint i = first; i <= last; ++i) { 414 hr = region_at(i); 415 _humongous_set.add(hr); 416 _hr_printer.alloc(hr); 417 } 418 419 return new_obj; 420 } 421 422 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 423 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 424 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 425 } 426 427 // If could fit into free regions w/o expansion, try. 428 // Otherwise, if can expand, do so. 429 // Otherwise, if using ex regions might help, try with ex given back. 430 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 431 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 432 433 _verifier->verify_region_sets_optional(); 434 435 uint first = G1_NO_HRM_INDEX; 436 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 437 438 if (obj_regions == 1) { 439 // Only one region to allocate, try to use a fast path by directly allocating 440 // from the free lists. Do not try to expand here, we will potentially do that 441 // later. 442 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 443 if (hr != NULL) { 444 first = hr->hrm_index(); 445 } 446 } else { 447 // We can't allocate humongous regions spanning more than one region while 448 // cleanupComplete() is running, since some of the regions we find to be 449 // empty might not yet be added to the free list. It is not straightforward 450 // to know in which list they are on so that we can remove them. We only 451 // need to do this if we need to allocate more than one region to satisfy the 452 // current humongous allocation request. If we are only allocating one region 453 // we use the one-region region allocation code (see above), that already 454 // potentially waits for regions from the secondary free list. 455 wait_while_free_regions_coming(); 456 append_secondary_free_list_if_not_empty_with_lock(); 457 458 // Policy: Try only empty regions (i.e. already committed first). Maybe we 459 // are lucky enough to find some. 460 first = _hrm.find_contiguous_only_empty(obj_regions); 461 if (first != G1_NO_HRM_INDEX) { 462 _hrm.allocate_free_regions_starting_at(first, obj_regions); 463 } 464 } 465 466 if (first == G1_NO_HRM_INDEX) { 467 // Policy: We could not find enough regions for the humongous object in the 468 // free list. Look through the heap to find a mix of free and uncommitted regions. 469 // If so, try expansion. 470 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 471 if (first != G1_NO_HRM_INDEX) { 472 // We found something. Make sure these regions are committed, i.e. expand 473 // the heap. Alternatively we could do a defragmentation GC. 474 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", 475 word_size * HeapWordSize); 476 477 478 _hrm.expand_at(first, obj_regions); 479 g1_policy()->record_new_heap_size(num_regions()); 480 481 #ifdef ASSERT 482 for (uint i = first; i < first + obj_regions; ++i) { 483 HeapRegion* hr = region_at(i); 484 assert(hr->is_free(), "sanity"); 485 assert(hr->is_empty(), "sanity"); 486 assert(is_on_master_free_list(hr), "sanity"); 487 } 488 #endif 489 _hrm.allocate_free_regions_starting_at(first, obj_regions); 490 } else { 491 // Policy: Potentially trigger a defragmentation GC. 492 } 493 } 494 495 HeapWord* result = NULL; 496 if (first != G1_NO_HRM_INDEX) { 497 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 498 word_size, context); 499 assert(result != NULL, "it should always return a valid result"); 500 501 // A successful humongous object allocation changes the used space 502 // information of the old generation so we need to recalculate the 503 // sizes and update the jstat counters here. 504 g1mm()->update_sizes(); 505 } 506 507 _verifier->verify_region_sets_optional(); 508 509 return result; 510 } 511 512 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 513 assert_heap_not_locked_and_not_at_safepoint(); 514 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 515 516 uint dummy_gc_count_before; 517 uint dummy_gclocker_retry_count = 0; 518 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 519 } 520 521 HeapWord* 522 G1CollectedHeap::mem_allocate(size_t word_size, 523 bool* gc_overhead_limit_was_exceeded) { 524 assert_heap_not_locked_and_not_at_safepoint(); 525 526 // Loop until the allocation is satisfied, or unsatisfied after GC. 527 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 528 uint gc_count_before; 529 530 HeapWord* result = NULL; 531 if (!is_humongous(word_size)) { 532 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 533 } else { 534 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 535 } 536 if (result != NULL) { 537 return result; 538 } 539 540 // Create the garbage collection operation... 541 VM_G1CollectForAllocation op(gc_count_before, word_size); 542 op.set_allocation_context(AllocationContext::current()); 543 544 // ...and get the VM thread to execute it. 545 VMThread::execute(&op); 546 547 if (op.prologue_succeeded() && op.pause_succeeded()) { 548 // If the operation was successful we'll return the result even 549 // if it is NULL. If the allocation attempt failed immediately 550 // after a Full GC, it's unlikely we'll be able to allocate now. 551 HeapWord* result = op.result(); 552 if (result != NULL && !is_humongous(word_size)) { 553 // Allocations that take place on VM operations do not do any 554 // card dirtying and we have to do it here. We only have to do 555 // this for non-humongous allocations, though. 556 dirty_young_block(result, word_size); 557 } 558 return result; 559 } else { 560 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 561 return NULL; 562 } 563 assert(op.result() == NULL, 564 "the result should be NULL if the VM op did not succeed"); 565 } 566 567 // Give a warning if we seem to be looping forever. 568 if ((QueuedAllocationWarningCount > 0) && 569 (try_count % QueuedAllocationWarningCount == 0)) { 570 log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count); 571 } 572 } 573 574 ShouldNotReachHere(); 575 return NULL; 576 } 577 578 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 579 AllocationContext_t context, 580 uint* gc_count_before_ret, 581 uint* gclocker_retry_count_ret) { 582 // Make sure you read the note in attempt_allocation_humongous(). 583 584 assert_heap_not_locked_and_not_at_safepoint(); 585 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 586 "be called for humongous allocation requests"); 587 588 // We should only get here after the first-level allocation attempt 589 // (attempt_allocation()) failed to allocate. 590 591 // We will loop until a) we manage to successfully perform the 592 // allocation or b) we successfully schedule a collection which 593 // fails to perform the allocation. b) is the only case when we'll 594 // return NULL. 595 HeapWord* result = NULL; 596 for (int try_count = 1; /* we'll return */; try_count += 1) { 597 bool should_try_gc; 598 uint gc_count_before; 599 600 { 601 MutexLockerEx x(Heap_lock); 602 result = _allocator->attempt_allocation_locked(word_size, context); 603 if (result != NULL) { 604 return result; 605 } 606 607 if (GCLocker::is_active_and_needs_gc()) { 608 if (g1_policy()->can_expand_young_list()) { 609 // No need for an ergo verbose message here, 610 // can_expand_young_list() does this when it returns true. 611 result = _allocator->attempt_allocation_force(word_size, context); 612 if (result != NULL) { 613 return result; 614 } 615 } 616 should_try_gc = false; 617 } else { 618 // The GCLocker may not be active but the GCLocker initiated 619 // GC may not yet have been performed (GCLocker::needs_gc() 620 // returns true). In this case we do not try this GC and 621 // wait until the GCLocker initiated GC is performed, and 622 // then retry the allocation. 623 if (GCLocker::needs_gc()) { 624 should_try_gc = false; 625 } else { 626 // Read the GC count while still holding the Heap_lock. 627 gc_count_before = total_collections(); 628 should_try_gc = true; 629 } 630 } 631 } 632 633 if (should_try_gc) { 634 bool succeeded; 635 result = do_collection_pause(word_size, gc_count_before, &succeeded, 636 GCCause::_g1_inc_collection_pause); 637 if (result != NULL) { 638 assert(succeeded, "only way to get back a non-NULL result"); 639 return result; 640 } 641 642 if (succeeded) { 643 // If we get here we successfully scheduled a collection which 644 // failed to allocate. No point in trying to allocate 645 // further. We'll just return NULL. 646 MutexLockerEx x(Heap_lock); 647 *gc_count_before_ret = total_collections(); 648 return NULL; 649 } 650 } else { 651 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 652 MutexLockerEx x(Heap_lock); 653 *gc_count_before_ret = total_collections(); 654 return NULL; 655 } 656 // The GCLocker is either active or the GCLocker initiated 657 // GC has not yet been performed. Stall until it is and 658 // then retry the allocation. 659 GCLocker::stall_until_clear(); 660 (*gclocker_retry_count_ret) += 1; 661 } 662 663 // We can reach here if we were unsuccessful in scheduling a 664 // collection (because another thread beat us to it) or if we were 665 // stalled due to the GC locker. In either can we should retry the 666 // allocation attempt in case another thread successfully 667 // performed a collection and reclaimed enough space. We do the 668 // first attempt (without holding the Heap_lock) here and the 669 // follow-on attempt will be at the start of the next loop 670 // iteration (after taking the Heap_lock). 671 result = _allocator->attempt_allocation(word_size, context); 672 if (result != NULL) { 673 return result; 674 } 675 676 // Give a warning if we seem to be looping forever. 677 if ((QueuedAllocationWarningCount > 0) && 678 (try_count % QueuedAllocationWarningCount == 0)) { 679 log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() " 680 "retries %d times", try_count); 681 } 682 } 683 684 ShouldNotReachHere(); 685 return NULL; 686 } 687 688 void G1CollectedHeap::begin_archive_alloc_range() { 689 assert_at_safepoint(true /* should_be_vm_thread */); 690 if (_archive_allocator == NULL) { 691 _archive_allocator = G1ArchiveAllocator::create_allocator(this); 692 } 693 } 694 695 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 696 // Allocations in archive regions cannot be of a size that would be considered 697 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 698 // may be different at archive-restore time. 699 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 700 } 701 702 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 703 assert_at_safepoint(true /* should_be_vm_thread */); 704 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 705 if (is_archive_alloc_too_large(word_size)) { 706 return NULL; 707 } 708 return _archive_allocator->archive_mem_allocate(word_size); 709 } 710 711 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 712 size_t end_alignment_in_bytes) { 713 assert_at_safepoint(true /* should_be_vm_thread */); 714 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 715 716 // Call complete_archive to do the real work, filling in the MemRegion 717 // array with the archive regions. 718 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 719 delete _archive_allocator; 720 _archive_allocator = NULL; 721 } 722 723 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 724 assert(ranges != NULL, "MemRegion array NULL"); 725 assert(count != 0, "No MemRegions provided"); 726 MemRegion reserved = _hrm.reserved(); 727 for (size_t i = 0; i < count; i++) { 728 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 729 return false; 730 } 731 } 732 return true; 733 } 734 735 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) { 736 assert(!is_init_completed(), "Expect to be called at JVM init time"); 737 assert(ranges != NULL, "MemRegion array NULL"); 738 assert(count != 0, "No MemRegions provided"); 739 MutexLockerEx x(Heap_lock); 740 741 MemRegion reserved = _hrm.reserved(); 742 HeapWord* prev_last_addr = NULL; 743 HeapRegion* prev_last_region = NULL; 744 745 // Temporarily disable pretouching of heap pages. This interface is used 746 // when mmap'ing archived heap data in, so pre-touching is wasted. 747 FlagSetting fs(AlwaysPreTouch, false); 748 749 // Enable archive object checking in G1MarkSweep. We have to let it know 750 // about each archive range, so that objects in those ranges aren't marked. 751 G1MarkSweep::enable_archive_object_check(); 752 753 // For each specified MemRegion range, allocate the corresponding G1 754 // regions and mark them as archive regions. We expect the ranges in 755 // ascending starting address order, without overlap. 756 for (size_t i = 0; i < count; i++) { 757 MemRegion curr_range = ranges[i]; 758 HeapWord* start_address = curr_range.start(); 759 size_t word_size = curr_range.word_size(); 760 HeapWord* last_address = curr_range.last(); 761 size_t commits = 0; 762 763 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 764 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 765 p2i(start_address), p2i(last_address)); 766 guarantee(start_address > prev_last_addr, 767 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 768 p2i(start_address), p2i(prev_last_addr)); 769 prev_last_addr = last_address; 770 771 // Check for ranges that start in the same G1 region in which the previous 772 // range ended, and adjust the start address so we don't try to allocate 773 // the same region again. If the current range is entirely within that 774 // region, skip it, just adjusting the recorded top. 775 HeapRegion* start_region = _hrm.addr_to_region(start_address); 776 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 777 start_address = start_region->end(); 778 if (start_address > last_address) { 779 increase_used(word_size * HeapWordSize); 780 start_region->set_top(last_address + 1); 781 continue; 782 } 783 start_region->set_top(start_address); 784 curr_range = MemRegion(start_address, last_address + 1); 785 start_region = _hrm.addr_to_region(start_address); 786 } 787 788 // Perform the actual region allocation, exiting if it fails. 789 // Then note how much new space we have allocated. 790 if (!_hrm.allocate_containing_regions(curr_range, &commits)) { 791 return false; 792 } 793 increase_used(word_size * HeapWordSize); 794 if (commits != 0) { 795 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 796 HeapRegion::GrainWords * HeapWordSize * commits); 797 798 } 799 800 // Mark each G1 region touched by the range as archive, add it to the old set, 801 // and set the allocation context and top. 802 HeapRegion* curr_region = _hrm.addr_to_region(start_address); 803 HeapRegion* last_region = _hrm.addr_to_region(last_address); 804 prev_last_region = last_region; 805 806 while (curr_region != NULL) { 807 assert(curr_region->is_empty() && !curr_region->is_pinned(), 808 "Region already in use (index %u)", curr_region->hrm_index()); 809 curr_region->set_allocation_context(AllocationContext::system()); 810 curr_region->set_archive(); 811 _hr_printer.alloc(curr_region); 812 _old_set.add(curr_region); 813 if (curr_region != last_region) { 814 curr_region->set_top(curr_region->end()); 815 curr_region = _hrm.next_region_in_heap(curr_region); 816 } else { 817 curr_region->set_top(last_address + 1); 818 curr_region = NULL; 819 } 820 } 821 822 // Notify mark-sweep of the archive range. 823 G1MarkSweep::set_range_archive(curr_range, true); 824 } 825 return true; 826 } 827 828 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 829 assert(!is_init_completed(), "Expect to be called at JVM init time"); 830 assert(ranges != NULL, "MemRegion array NULL"); 831 assert(count != 0, "No MemRegions provided"); 832 MemRegion reserved = _hrm.reserved(); 833 HeapWord *prev_last_addr = NULL; 834 HeapRegion* prev_last_region = NULL; 835 836 // For each MemRegion, create filler objects, if needed, in the G1 regions 837 // that contain the address range. The address range actually within the 838 // MemRegion will not be modified. That is assumed to have been initialized 839 // elsewhere, probably via an mmap of archived heap data. 840 MutexLockerEx x(Heap_lock); 841 for (size_t i = 0; i < count; i++) { 842 HeapWord* start_address = ranges[i].start(); 843 HeapWord* last_address = ranges[i].last(); 844 845 assert(reserved.contains(start_address) && reserved.contains(last_address), 846 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 847 p2i(start_address), p2i(last_address)); 848 assert(start_address > prev_last_addr, 849 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 850 p2i(start_address), p2i(prev_last_addr)); 851 852 HeapRegion* start_region = _hrm.addr_to_region(start_address); 853 HeapRegion* last_region = _hrm.addr_to_region(last_address); 854 HeapWord* bottom_address = start_region->bottom(); 855 856 // Check for a range beginning in the same region in which the 857 // previous one ended. 858 if (start_region == prev_last_region) { 859 bottom_address = prev_last_addr + 1; 860 } 861 862 // Verify that the regions were all marked as archive regions by 863 // alloc_archive_regions. 864 HeapRegion* curr_region = start_region; 865 while (curr_region != NULL) { 866 guarantee(curr_region->is_archive(), 867 "Expected archive region at index %u", curr_region->hrm_index()); 868 if (curr_region != last_region) { 869 curr_region = _hrm.next_region_in_heap(curr_region); 870 } else { 871 curr_region = NULL; 872 } 873 } 874 875 prev_last_addr = last_address; 876 prev_last_region = last_region; 877 878 // Fill the memory below the allocated range with dummy object(s), 879 // if the region bottom does not match the range start, or if the previous 880 // range ended within the same G1 region, and there is a gap. 881 if (start_address != bottom_address) { 882 size_t fill_size = pointer_delta(start_address, bottom_address); 883 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 884 increase_used(fill_size * HeapWordSize); 885 } 886 } 887 } 888 889 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size, 890 uint* gc_count_before_ret, 891 uint* gclocker_retry_count_ret) { 892 assert_heap_not_locked_and_not_at_safepoint(); 893 assert(!is_humongous(word_size), "attempt_allocation() should not " 894 "be called for humongous allocation requests"); 895 896 AllocationContext_t context = AllocationContext::current(); 897 HeapWord* result = _allocator->attempt_allocation(word_size, context); 898 899 if (result == NULL) { 900 result = attempt_allocation_slow(word_size, 901 context, 902 gc_count_before_ret, 903 gclocker_retry_count_ret); 904 } 905 assert_heap_not_locked(); 906 if (result != NULL) { 907 dirty_young_block(result, word_size); 908 } 909 return result; 910 } 911 912 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 913 assert(!is_init_completed(), "Expect to be called at JVM init time"); 914 assert(ranges != NULL, "MemRegion array NULL"); 915 assert(count != 0, "No MemRegions provided"); 916 MemRegion reserved = _hrm.reserved(); 917 HeapWord* prev_last_addr = NULL; 918 HeapRegion* prev_last_region = NULL; 919 size_t size_used = 0; 920 size_t uncommitted_regions = 0; 921 922 // For each Memregion, free the G1 regions that constitute it, and 923 // notify mark-sweep that the range is no longer to be considered 'archive.' 924 MutexLockerEx x(Heap_lock); 925 for (size_t i = 0; i < count; i++) { 926 HeapWord* start_address = ranges[i].start(); 927 HeapWord* last_address = ranges[i].last(); 928 929 assert(reserved.contains(start_address) && reserved.contains(last_address), 930 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 931 p2i(start_address), p2i(last_address)); 932 assert(start_address > prev_last_addr, 933 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 934 p2i(start_address), p2i(prev_last_addr)); 935 size_used += ranges[i].byte_size(); 936 prev_last_addr = last_address; 937 938 HeapRegion* start_region = _hrm.addr_to_region(start_address); 939 HeapRegion* last_region = _hrm.addr_to_region(last_address); 940 941 // Check for ranges that start in the same G1 region in which the previous 942 // range ended, and adjust the start address so we don't try to free 943 // the same region again. If the current range is entirely within that 944 // region, skip it. 945 if (start_region == prev_last_region) { 946 start_address = start_region->end(); 947 if (start_address > last_address) { 948 continue; 949 } 950 start_region = _hrm.addr_to_region(start_address); 951 } 952 prev_last_region = last_region; 953 954 // After verifying that each region was marked as an archive region by 955 // alloc_archive_regions, set it free and empty and uncommit it. 956 HeapRegion* curr_region = start_region; 957 while (curr_region != NULL) { 958 guarantee(curr_region->is_archive(), 959 "Expected archive region at index %u", curr_region->hrm_index()); 960 uint curr_index = curr_region->hrm_index(); 961 _old_set.remove(curr_region); 962 curr_region->set_free(); 963 curr_region->set_top(curr_region->bottom()); 964 if (curr_region != last_region) { 965 curr_region = _hrm.next_region_in_heap(curr_region); 966 } else { 967 curr_region = NULL; 968 } 969 _hrm.shrink_at(curr_index, 1); 970 uncommitted_regions++; 971 } 972 973 // Notify mark-sweep that this is no longer an archive range. 974 G1MarkSweep::set_range_archive(ranges[i], false); 975 } 976 977 if (uncommitted_regions != 0) { 978 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 979 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 980 } 981 decrease_used(size_used); 982 } 983 984 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 985 uint* gc_count_before_ret, 986 uint* gclocker_retry_count_ret) { 987 // The structure of this method has a lot of similarities to 988 // attempt_allocation_slow(). The reason these two were not merged 989 // into a single one is that such a method would require several "if 990 // allocation is not humongous do this, otherwise do that" 991 // conditional paths which would obscure its flow. In fact, an early 992 // version of this code did use a unified method which was harder to 993 // follow and, as a result, it had subtle bugs that were hard to 994 // track down. So keeping these two methods separate allows each to 995 // be more readable. It will be good to keep these two in sync as 996 // much as possible. 997 998 assert_heap_not_locked_and_not_at_safepoint(); 999 assert(is_humongous(word_size), "attempt_allocation_humongous() " 1000 "should only be called for humongous allocations"); 1001 1002 // Humongous objects can exhaust the heap quickly, so we should check if we 1003 // need to start a marking cycle at each humongous object allocation. We do 1004 // the check before we do the actual allocation. The reason for doing it 1005 // before the allocation is that we avoid having to keep track of the newly 1006 // allocated memory while we do a GC. 1007 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1008 word_size)) { 1009 collect(GCCause::_g1_humongous_allocation); 1010 } 1011 1012 // We will loop until a) we manage to successfully perform the 1013 // allocation or b) we successfully schedule a collection which 1014 // fails to perform the allocation. b) is the only case when we'll 1015 // return NULL. 1016 HeapWord* result = NULL; 1017 for (int try_count = 1; /* we'll return */; try_count += 1) { 1018 bool should_try_gc; 1019 uint gc_count_before; 1020 1021 { 1022 MutexLockerEx x(Heap_lock); 1023 1024 // Given that humongous objects are not allocated in young 1025 // regions, we'll first try to do the allocation without doing a 1026 // collection hoping that there's enough space in the heap. 1027 result = humongous_obj_allocate(word_size, AllocationContext::current()); 1028 if (result != NULL) { 1029 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 1030 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 1031 return result; 1032 } 1033 1034 if (GCLocker::is_active_and_needs_gc()) { 1035 should_try_gc = false; 1036 } else { 1037 // The GCLocker may not be active but the GCLocker initiated 1038 // GC may not yet have been performed (GCLocker::needs_gc() 1039 // returns true). In this case we do not try this GC and 1040 // wait until the GCLocker initiated GC is performed, and 1041 // then retry the allocation. 1042 if (GCLocker::needs_gc()) { 1043 should_try_gc = false; 1044 } else { 1045 // Read the GC count while still holding the Heap_lock. 1046 gc_count_before = total_collections(); 1047 should_try_gc = true; 1048 } 1049 } 1050 } 1051 1052 if (should_try_gc) { 1053 // If we failed to allocate the humongous object, we should try to 1054 // do a collection pause (if we're allowed) in case it reclaims 1055 // enough space for the allocation to succeed after the pause. 1056 1057 bool succeeded; 1058 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1059 GCCause::_g1_humongous_allocation); 1060 if (result != NULL) { 1061 assert(succeeded, "only way to get back a non-NULL result"); 1062 return result; 1063 } 1064 1065 if (succeeded) { 1066 // If we get here we successfully scheduled a collection which 1067 // failed to allocate. No point in trying to allocate 1068 // further. We'll just return NULL. 1069 MutexLockerEx x(Heap_lock); 1070 *gc_count_before_ret = total_collections(); 1071 return NULL; 1072 } 1073 } else { 1074 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1075 MutexLockerEx x(Heap_lock); 1076 *gc_count_before_ret = total_collections(); 1077 return NULL; 1078 } 1079 // The GCLocker is either active or the GCLocker initiated 1080 // GC has not yet been performed. Stall until it is and 1081 // then retry the allocation. 1082 GCLocker::stall_until_clear(); 1083 (*gclocker_retry_count_ret) += 1; 1084 } 1085 1086 // We can reach here if we were unsuccessful in scheduling a 1087 // collection (because another thread beat us to it) or if we were 1088 // stalled due to the GC locker. In either can we should retry the 1089 // allocation attempt in case another thread successfully 1090 // performed a collection and reclaimed enough space. Give a 1091 // warning if we seem to be looping forever. 1092 1093 if ((QueuedAllocationWarningCount > 0) && 1094 (try_count % QueuedAllocationWarningCount == 0)) { 1095 log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() " 1096 "retries %d times", try_count); 1097 } 1098 } 1099 1100 ShouldNotReachHere(); 1101 return NULL; 1102 } 1103 1104 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1105 AllocationContext_t context, 1106 bool expect_null_mutator_alloc_region) { 1107 assert_at_safepoint(true /* should_be_vm_thread */); 1108 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region, 1109 "the current alloc region was unexpectedly found to be non-NULL"); 1110 1111 if (!is_humongous(word_size)) { 1112 return _allocator->attempt_allocation_locked(word_size, context); 1113 } else { 1114 HeapWord* result = humongous_obj_allocate(word_size, context); 1115 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1116 collector_state()->set_initiate_conc_mark_if_possible(true); 1117 } 1118 return result; 1119 } 1120 1121 ShouldNotReachHere(); 1122 } 1123 1124 class PostMCRemSetClearClosure: public HeapRegionClosure { 1125 G1CollectedHeap* _g1h; 1126 ModRefBarrierSet* _mr_bs; 1127 public: 1128 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1129 _g1h(g1h), _mr_bs(mr_bs) {} 1130 1131 bool doHeapRegion(HeapRegion* r) { 1132 HeapRegionRemSet* hrrs = r->rem_set(); 1133 1134 _g1h->reset_gc_time_stamps(r); 1135 1136 if (r->is_continues_humongous()) { 1137 // We'll assert that the strong code root list and RSet is empty 1138 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1139 assert(hrrs->occupied() == 0, "RSet should be empty"); 1140 } else { 1141 hrrs->clear(); 1142 } 1143 // You might think here that we could clear just the cards 1144 // corresponding to the used region. But no: if we leave a dirty card 1145 // in a region we might allocate into, then it would prevent that card 1146 // from being enqueued, and cause it to be missed. 1147 // Re: the performance cost: we shouldn't be doing full GC anyway! 1148 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1149 1150 return false; 1151 } 1152 }; 1153 1154 void G1CollectedHeap::clear_rsets_post_compaction() { 1155 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1156 heap_region_iterate(&rs_clear); 1157 } 1158 1159 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1160 G1CollectedHeap* _g1h; 1161 UpdateRSOopClosure _cl; 1162 public: 1163 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) : 1164 _cl(g1->g1_rem_set(), worker_i), 1165 _g1h(g1) 1166 { } 1167 1168 bool doHeapRegion(HeapRegion* r) { 1169 if (!r->is_continues_humongous()) { 1170 _cl.set_from(r); 1171 r->oop_iterate(&_cl); 1172 } 1173 return false; 1174 } 1175 }; 1176 1177 class ParRebuildRSTask: public AbstractGangTask { 1178 G1CollectedHeap* _g1; 1179 HeapRegionClaimer _hrclaimer; 1180 1181 public: 1182 ParRebuildRSTask(G1CollectedHeap* g1) : 1183 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {} 1184 1185 void work(uint worker_id) { 1186 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1187 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer); 1188 } 1189 }; 1190 1191 class PostCompactionPrinterClosure: public HeapRegionClosure { 1192 private: 1193 G1HRPrinter* _hr_printer; 1194 public: 1195 bool doHeapRegion(HeapRegion* hr) { 1196 assert(!hr->is_young(), "not expecting to find young regions"); 1197 _hr_printer->post_compaction(hr); 1198 return false; 1199 } 1200 1201 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1202 : _hr_printer(hr_printer) { } 1203 }; 1204 1205 void G1CollectedHeap::print_hrm_post_compaction() { 1206 if (_hr_printer.is_active()) { 1207 PostCompactionPrinterClosure cl(hr_printer()); 1208 heap_region_iterate(&cl); 1209 } 1210 1211 } 1212 1213 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1214 bool clear_all_soft_refs) { 1215 assert_at_safepoint(true /* should_be_vm_thread */); 1216 1217 if (GCLocker::check_active_before_gc()) { 1218 return false; 1219 } 1220 1221 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1222 gc_timer->register_gc_start(); 1223 1224 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1225 GCIdMark gc_id_mark; 1226 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1227 1228 SvcGCMarker sgcm(SvcGCMarker::FULL); 1229 ResourceMark rm; 1230 1231 print_heap_before_gc(); 1232 print_heap_regions(); 1233 trace_heap_before_gc(gc_tracer); 1234 1235 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1236 1237 _verifier->verify_region_sets_optional(); 1238 1239 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1240 collector_policy()->should_clear_all_soft_refs(); 1241 1242 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1243 1244 { 1245 IsGCActiveMark x; 1246 1247 // Timing 1248 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1249 GCTraceCPUTime tcpu; 1250 1251 { 1252 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1253 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1254 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1255 1256 G1HeapTransition heap_transition(this); 1257 g1_policy()->record_full_collection_start(); 1258 1259 // Note: When we have a more flexible GC logging framework that 1260 // allows us to add optional attributes to a GC log record we 1261 // could consider timing and reporting how long we wait in the 1262 // following two methods. 1263 wait_while_free_regions_coming(); 1264 // If we start the compaction before the CM threads finish 1265 // scanning the root regions we might trip them over as we'll 1266 // be moving objects / updating references. So let's wait until 1267 // they are done. By telling them to abort, they should complete 1268 // early. 1269 _cm->root_regions()->abort(); 1270 _cm->root_regions()->wait_until_scan_finished(); 1271 append_secondary_free_list_if_not_empty_with_lock(); 1272 1273 gc_prologue(true); 1274 increment_total_collections(true /* full gc */); 1275 increment_old_marking_cycles_started(); 1276 1277 assert(used() == recalculate_used(), "Should be equal"); 1278 1279 _verifier->verify_before_gc(); 1280 1281 _verifier->check_bitmaps("Full GC Start"); 1282 pre_full_gc_dump(gc_timer); 1283 1284 #if defined(COMPILER2) || INCLUDE_JVMCI 1285 DerivedPointerTable::clear(); 1286 #endif 1287 1288 // Disable discovery and empty the discovered lists 1289 // for the CM ref processor. 1290 ref_processor_cm()->disable_discovery(); 1291 ref_processor_cm()->abandon_partial_discovery(); 1292 ref_processor_cm()->verify_no_references_recorded(); 1293 1294 // Abandon current iterations of concurrent marking and concurrent 1295 // refinement, if any are in progress. 1296 concurrent_mark()->abort(); 1297 1298 // Make sure we'll choose a new allocation region afterwards. 1299 _allocator->release_mutator_alloc_region(); 1300 _allocator->abandon_gc_alloc_regions(); 1301 g1_rem_set()->cleanupHRRS(); 1302 1303 // We may have added regions to the current incremental collection 1304 // set between the last GC or pause and now. We need to clear the 1305 // incremental collection set and then start rebuilding it afresh 1306 // after this full GC. 1307 abandon_collection_set(collection_set()->inc_head()); 1308 collection_set()->clear_incremental(); 1309 collection_set()->stop_incremental_building(); 1310 1311 tear_down_region_sets(false /* free_list_only */); 1312 collector_state()->set_gcs_are_young(true); 1313 1314 // See the comments in g1CollectedHeap.hpp and 1315 // G1CollectedHeap::ref_processing_init() about 1316 // how reference processing currently works in G1. 1317 1318 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1319 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1320 1321 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1322 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1323 1324 ref_processor_stw()->enable_discovery(); 1325 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1326 1327 // Do collection work 1328 { 1329 HandleMark hm; // Discard invalid handles created during gc 1330 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1331 } 1332 1333 assert(num_free_regions() == 0, "we should not have added any free regions"); 1334 rebuild_region_sets(false /* free_list_only */); 1335 1336 // Enqueue any discovered reference objects that have 1337 // not been removed from the discovered lists. 1338 ref_processor_stw()->enqueue_discovered_references(); 1339 1340 #if defined(COMPILER2) || INCLUDE_JVMCI 1341 DerivedPointerTable::update_pointers(); 1342 #endif 1343 1344 MemoryService::track_memory_usage(); 1345 1346 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1347 ref_processor_stw()->verify_no_references_recorded(); 1348 1349 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1350 ClassLoaderDataGraph::purge(); 1351 MetaspaceAux::verify_metrics(); 1352 1353 // Note: since we've just done a full GC, concurrent 1354 // marking is no longer active. Therefore we need not 1355 // re-enable reference discovery for the CM ref processor. 1356 // That will be done at the start of the next marking cycle. 1357 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1358 ref_processor_cm()->verify_no_references_recorded(); 1359 1360 reset_gc_time_stamp(); 1361 // Since everything potentially moved, we will clear all remembered 1362 // sets, and clear all cards. Later we will rebuild remembered 1363 // sets. We will also reset the GC time stamps of the regions. 1364 clear_rsets_post_compaction(); 1365 check_gc_time_stamps(); 1366 1367 resize_if_necessary_after_full_collection(); 1368 1369 // We should do this after we potentially resize the heap so 1370 // that all the COMMIT / UNCOMMIT events are generated before 1371 // the compaction events. 1372 print_hrm_post_compaction(); 1373 1374 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1375 if (hot_card_cache->use_cache()) { 1376 hot_card_cache->reset_card_counts(); 1377 hot_card_cache->reset_hot_cache(); 1378 } 1379 1380 // Rebuild remembered sets of all regions. 1381 uint n_workers = 1382 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1383 workers()->active_workers(), 1384 Threads::number_of_non_daemon_threads()); 1385 workers()->set_active_workers(n_workers); 1386 1387 ParRebuildRSTask rebuild_rs_task(this); 1388 workers()->run_task(&rebuild_rs_task); 1389 1390 // Rebuild the strong code root lists for each region 1391 rebuild_strong_code_roots(); 1392 1393 if (true) { // FIXME 1394 MetaspaceGC::compute_new_size(); 1395 } 1396 1397 #ifdef TRACESPINNING 1398 ParallelTaskTerminator::print_termination_counts(); 1399 #endif 1400 1401 // Discard all rset updates 1402 JavaThread::dirty_card_queue_set().abandon_logs(); 1403 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1404 1405 // At this point there should be no regions in the 1406 // entire heap tagged as young. 1407 assert(check_young_list_empty(true /* check_heap */), 1408 "young list should be empty at this point"); 1409 1410 // Update the number of full collections that have been completed. 1411 increment_old_marking_cycles_completed(false /* concurrent */); 1412 1413 _hrm.verify_optional(); 1414 _verifier->verify_region_sets_optional(); 1415 1416 _verifier->verify_after_gc(); 1417 1418 // Clear the previous marking bitmap, if needed for bitmap verification. 1419 // Note we cannot do this when we clear the next marking bitmap in 1420 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1421 // objects marked during a full GC against the previous bitmap. 1422 // But we need to clear it before calling check_bitmaps below since 1423 // the full GC has compacted objects and updated TAMS but not updated 1424 // the prev bitmap. 1425 if (G1VerifyBitmaps) { 1426 ((G1CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1427 } 1428 _verifier->check_bitmaps("Full GC End"); 1429 1430 // Start a new incremental collection set for the next pause 1431 assert(collection_set()->head() == NULL, "must be"); 1432 collection_set()->start_incremental_building(); 1433 1434 clear_cset_fast_test(); 1435 1436 _allocator->init_mutator_alloc_region(); 1437 1438 g1_policy()->record_full_collection_end(); 1439 1440 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1441 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1442 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1443 // before any GC notifications are raised. 1444 g1mm()->update_sizes(); 1445 1446 gc_epilogue(true); 1447 1448 heap_transition.print(); 1449 1450 print_heap_after_gc(); 1451 print_heap_regions(); 1452 trace_heap_after_gc(gc_tracer); 1453 1454 post_full_gc_dump(gc_timer); 1455 } 1456 1457 gc_timer->register_gc_end(); 1458 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1459 } 1460 1461 return true; 1462 } 1463 1464 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1465 // Currently, there is no facility in the do_full_collection(bool) API to notify 1466 // the caller that the collection did not succeed (e.g., because it was locked 1467 // out by the GC locker). So, right now, we'll ignore the return value. 1468 bool dummy = do_full_collection(true, /* explicit_gc */ 1469 clear_all_soft_refs); 1470 } 1471 1472 void G1CollectedHeap::resize_if_necessary_after_full_collection() { 1473 // Include bytes that will be pre-allocated to support collections, as "used". 1474 const size_t used_after_gc = used(); 1475 const size_t capacity_after_gc = capacity(); 1476 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1477 1478 // This is enforced in arguments.cpp. 1479 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1480 "otherwise the code below doesn't make sense"); 1481 1482 // We don't have floating point command-line arguments 1483 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1484 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1485 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1486 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1487 1488 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1489 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1490 1491 // We have to be careful here as these two calculations can overflow 1492 // 32-bit size_t's. 1493 double used_after_gc_d = (double) used_after_gc; 1494 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1495 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1496 1497 // Let's make sure that they are both under the max heap size, which 1498 // by default will make them fit into a size_t. 1499 double desired_capacity_upper_bound = (double) max_heap_size; 1500 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1501 desired_capacity_upper_bound); 1502 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1503 desired_capacity_upper_bound); 1504 1505 // We can now safely turn them into size_t's. 1506 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1507 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1508 1509 // This assert only makes sense here, before we adjust them 1510 // with respect to the min and max heap size. 1511 assert(minimum_desired_capacity <= maximum_desired_capacity, 1512 "minimum_desired_capacity = " SIZE_FORMAT ", " 1513 "maximum_desired_capacity = " SIZE_FORMAT, 1514 minimum_desired_capacity, maximum_desired_capacity); 1515 1516 // Should not be greater than the heap max size. No need to adjust 1517 // it with respect to the heap min size as it's a lower bound (i.e., 1518 // we'll try to make the capacity larger than it, not smaller). 1519 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1520 // Should not be less than the heap min size. No need to adjust it 1521 // with respect to the heap max size as it's an upper bound (i.e., 1522 // we'll try to make the capacity smaller than it, not greater). 1523 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1524 1525 if (capacity_after_gc < minimum_desired_capacity) { 1526 // Don't expand unless it's significant 1527 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1528 1529 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). " 1530 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1531 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio); 1532 1533 expand(expand_bytes); 1534 1535 // No expansion, now see if we want to shrink 1536 } else if (capacity_after_gc > maximum_desired_capacity) { 1537 // Capacity too large, compute shrinking size 1538 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1539 1540 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). " 1541 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1542 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio); 1543 1544 shrink(shrink_bytes); 1545 } 1546 } 1547 1548 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1549 AllocationContext_t context, 1550 bool do_gc, 1551 bool clear_all_soft_refs, 1552 bool expect_null_mutator_alloc_region, 1553 bool* gc_succeeded) { 1554 *gc_succeeded = true; 1555 // Let's attempt the allocation first. 1556 HeapWord* result = 1557 attempt_allocation_at_safepoint(word_size, 1558 context, 1559 expect_null_mutator_alloc_region); 1560 if (result != NULL) { 1561 assert(*gc_succeeded, "sanity"); 1562 return result; 1563 } 1564 1565 // In a G1 heap, we're supposed to keep allocation from failing by 1566 // incremental pauses. Therefore, at least for now, we'll favor 1567 // expansion over collection. (This might change in the future if we can 1568 // do something smarter than full collection to satisfy a failed alloc.) 1569 result = expand_and_allocate(word_size, context); 1570 if (result != NULL) { 1571 assert(*gc_succeeded, "sanity"); 1572 return result; 1573 } 1574 1575 if (do_gc) { 1576 // Expansion didn't work, we'll try to do a Full GC. 1577 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1578 clear_all_soft_refs); 1579 } 1580 1581 return NULL; 1582 } 1583 1584 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1585 AllocationContext_t context, 1586 bool* succeeded) { 1587 assert_at_safepoint(true /* should_be_vm_thread */); 1588 1589 // Attempts to allocate followed by Full GC. 1590 HeapWord* result = 1591 satisfy_failed_allocation_helper(word_size, 1592 context, 1593 true, /* do_gc */ 1594 false, /* clear_all_soft_refs */ 1595 false, /* expect_null_mutator_alloc_region */ 1596 succeeded); 1597 1598 if (result != NULL || !*succeeded) { 1599 return result; 1600 } 1601 1602 // Attempts to allocate followed by Full GC that will collect all soft references. 1603 result = satisfy_failed_allocation_helper(word_size, 1604 context, 1605 true, /* do_gc */ 1606 true, /* clear_all_soft_refs */ 1607 true, /* expect_null_mutator_alloc_region */ 1608 succeeded); 1609 1610 if (result != NULL || !*succeeded) { 1611 return result; 1612 } 1613 1614 // Attempts to allocate, no GC 1615 result = satisfy_failed_allocation_helper(word_size, 1616 context, 1617 false, /* do_gc */ 1618 false, /* clear_all_soft_refs */ 1619 true, /* expect_null_mutator_alloc_region */ 1620 succeeded); 1621 1622 if (result != NULL) { 1623 assert(*succeeded, "sanity"); 1624 return result; 1625 } 1626 1627 assert(!collector_policy()->should_clear_all_soft_refs(), 1628 "Flag should have been handled and cleared prior to this point"); 1629 1630 // What else? We might try synchronous finalization later. If the total 1631 // space available is large enough for the allocation, then a more 1632 // complete compaction phase than we've tried so far might be 1633 // appropriate. 1634 assert(*succeeded, "sanity"); 1635 return NULL; 1636 } 1637 1638 // Attempting to expand the heap sufficiently 1639 // to support an allocation of the given "word_size". If 1640 // successful, perform the allocation and return the address of the 1641 // allocated block, or else "NULL". 1642 1643 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1644 assert_at_safepoint(true /* should_be_vm_thread */); 1645 1646 _verifier->verify_region_sets_optional(); 1647 1648 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1649 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1650 word_size * HeapWordSize); 1651 1652 1653 if (expand(expand_bytes)) { 1654 _hrm.verify_optional(); 1655 _verifier->verify_region_sets_optional(); 1656 return attempt_allocation_at_safepoint(word_size, 1657 context, 1658 false /* expect_null_mutator_alloc_region */); 1659 } 1660 return NULL; 1661 } 1662 1663 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) { 1664 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1665 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1666 HeapRegion::GrainBytes); 1667 1668 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B", 1669 expand_bytes, aligned_expand_bytes); 1670 1671 if (is_maximal_no_gc()) { 1672 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1673 return false; 1674 } 1675 1676 double expand_heap_start_time_sec = os::elapsedTime(); 1677 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1678 assert(regions_to_expand > 0, "Must expand by at least one region"); 1679 1680 uint expanded_by = _hrm.expand_by(regions_to_expand); 1681 if (expand_time_ms != NULL) { 1682 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1683 } 1684 1685 if (expanded_by > 0) { 1686 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1687 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1688 g1_policy()->record_new_heap_size(num_regions()); 1689 } else { 1690 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1691 1692 // The expansion of the virtual storage space was unsuccessful. 1693 // Let's see if it was because we ran out of swap. 1694 if (G1ExitOnExpansionFailure && 1695 _hrm.available() >= regions_to_expand) { 1696 // We had head room... 1697 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1698 } 1699 } 1700 return regions_to_expand > 0; 1701 } 1702 1703 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1704 size_t aligned_shrink_bytes = 1705 ReservedSpace::page_align_size_down(shrink_bytes); 1706 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1707 HeapRegion::GrainBytes); 1708 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1709 1710 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1711 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1712 1713 1714 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", 1715 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1716 if (num_regions_removed > 0) { 1717 g1_policy()->record_new_heap_size(num_regions()); 1718 } else { 1719 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1720 } 1721 } 1722 1723 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1724 _verifier->verify_region_sets_optional(); 1725 1726 // We should only reach here at the end of a Full GC which means we 1727 // should not not be holding to any GC alloc regions. The method 1728 // below will make sure of that and do any remaining clean up. 1729 _allocator->abandon_gc_alloc_regions(); 1730 1731 // Instead of tearing down / rebuilding the free lists here, we 1732 // could instead use the remove_all_pending() method on free_list to 1733 // remove only the ones that we need to remove. 1734 tear_down_region_sets(true /* free_list_only */); 1735 shrink_helper(shrink_bytes); 1736 rebuild_region_sets(true /* free_list_only */); 1737 1738 _hrm.verify_optional(); 1739 _verifier->verify_region_sets_optional(); 1740 } 1741 1742 // Public methods. 1743 1744 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1745 CollectedHeap(), 1746 _g1_policy(policy_), 1747 _collection_set(this), 1748 _dirty_card_queue_set(false), 1749 _is_alive_closure_cm(this), 1750 _is_alive_closure_stw(this), 1751 _ref_processor_cm(NULL), 1752 _ref_processor_stw(NULL), 1753 _bot(NULL), 1754 _cg1r(NULL), 1755 _g1mm(NULL), 1756 _refine_cte_cl(NULL), 1757 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1758 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1759 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1760 _humongous_reclaim_candidates(), 1761 _has_humongous_reclaim_candidates(false), 1762 _archive_allocator(NULL), 1763 _free_regions_coming(false), 1764 _young_list(new YoungList(this)), 1765 _gc_time_stamp(0), 1766 _summary_bytes_used(0), 1767 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1768 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1769 _expand_heap_after_alloc_failure(true), 1770 _old_marking_cycles_started(0), 1771 _old_marking_cycles_completed(0), 1772 _heap_summary_sent(false), 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_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1779 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1780 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1781 1782 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1783 /* are_GC_task_threads */true, 1784 /* are_ConcurrentGC_threads */false); 1785 _workers->initialize_workers(); 1786 _verifier = new G1HeapVerifier(this); 1787 1788 _allocator = G1Allocator::create_allocator(this); 1789 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1790 1791 // Override the default _filler_array_max_size so that no humongous filler 1792 // objects are created. 1793 _filler_array_max_size = _humongous_object_threshold_in_words; 1794 1795 uint n_queues = ParallelGCThreads; 1796 _task_queues = new RefToScanQueueSet(n_queues); 1797 1798 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1799 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC); 1800 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1801 1802 for (uint i = 0; i < n_queues; i++) { 1803 RefToScanQueue* q = new RefToScanQueue(); 1804 q->initialize(); 1805 _task_queues->register_queue(i, q); 1806 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1807 } 1808 clear_cset_start_regions(); 1809 1810 // Initialize the G1EvacuationFailureALot counters and flags. 1811 NOT_PRODUCT(reset_evacuation_should_fail();) 1812 1813 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1814 } 1815 1816 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1817 size_t size, 1818 size_t translation_factor) { 1819 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1820 // Allocate a new reserved space, preferring to use large pages. 1821 ReservedSpace rs(size, preferred_page_size); 1822 G1RegionToSpaceMapper* result = 1823 G1RegionToSpaceMapper::create_mapper(rs, 1824 size, 1825 rs.alignment(), 1826 HeapRegion::GrainBytes, 1827 translation_factor, 1828 mtGC); 1829 if (TracePageSizes) { 1830 tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT, 1831 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size); 1832 } 1833 return result; 1834 } 1835 1836 jint G1CollectedHeap::initialize() { 1837 CollectedHeap::pre_initialize(); 1838 os::enable_vtime(); 1839 1840 // Necessary to satisfy locking discipline assertions. 1841 1842 MutexLocker x(Heap_lock); 1843 1844 // While there are no constraints in the GC code that HeapWordSize 1845 // be any particular value, there are multiple other areas in the 1846 // system which believe this to be true (e.g. oop->object_size in some 1847 // cases incorrectly returns the size in wordSize units rather than 1848 // HeapWordSize). 1849 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1850 1851 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1852 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1853 size_t heap_alignment = collector_policy()->heap_alignment(); 1854 1855 // Ensure that the sizes are properly aligned. 1856 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1857 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1858 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1859 1860 _refine_cte_cl = new RefineCardTableEntryClosure(); 1861 1862 jint ecode = JNI_OK; 1863 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode); 1864 if (_cg1r == NULL) { 1865 return ecode; 1866 } 1867 1868 // Reserve the maximum. 1869 1870 // When compressed oops are enabled, the preferred heap base 1871 // is calculated by subtracting the requested size from the 1872 // 32Gb boundary and using the result as the base address for 1873 // heap reservation. If the requested size is not aligned to 1874 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1875 // into the ReservedHeapSpace constructor) then the actual 1876 // base of the reserved heap may end up differing from the 1877 // address that was requested (i.e. the preferred heap base). 1878 // If this happens then we could end up using a non-optimal 1879 // compressed oops mode. 1880 1881 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1882 heap_alignment); 1883 1884 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1885 1886 // Create the barrier set for the entire reserved region. 1887 G1SATBCardTableLoggingModRefBS* bs 1888 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 1889 bs->initialize(); 1890 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 1891 set_barrier_set(bs); 1892 1893 // Also create a G1 rem set. 1894 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 1895 1896 // Carve out the G1 part of the heap. 1897 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1898 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 1899 G1RegionToSpaceMapper* heap_storage = 1900 G1RegionToSpaceMapper::create_mapper(g1_rs, 1901 g1_rs.size(), 1902 page_size, 1903 HeapRegion::GrainBytes, 1904 1, 1905 mtJavaHeap); 1906 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(), 1907 max_byte_size, page_size, 1908 heap_rs.base(), 1909 heap_rs.size()); 1910 heap_storage->set_mapping_changed_listener(&_listener); 1911 1912 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1913 G1RegionToSpaceMapper* bot_storage = 1914 create_aux_memory_mapper("Block offset table", 1915 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1916 G1BlockOffsetTable::heap_map_factor()); 1917 1918 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 1919 G1RegionToSpaceMapper* cardtable_storage = 1920 create_aux_memory_mapper("Card table", 1921 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize), 1922 G1SATBCardTableLoggingModRefBS::heap_map_factor()); 1923 1924 G1RegionToSpaceMapper* card_counts_storage = 1925 create_aux_memory_mapper("Card counts table", 1926 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1927 G1CardCounts::heap_map_factor()); 1928 1929 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1930 G1RegionToSpaceMapper* prev_bitmap_storage = 1931 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1932 G1RegionToSpaceMapper* next_bitmap_storage = 1933 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1934 1935 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1936 g1_barrier_set()->initialize(cardtable_storage); 1937 // Do later initialization work for concurrent refinement. 1938 _cg1r->init(card_counts_storage); 1939 1940 // 6843694 - ensure that the maximum region index can fit 1941 // in the remembered set structures. 1942 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1943 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1944 1945 G1RemSet::initialize(max_regions()); 1946 1947 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1948 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1949 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1950 "too many cards per region"); 1951 1952 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1953 1954 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1955 1956 { 1957 HeapWord* start = _hrm.reserved().start(); 1958 HeapWord* end = _hrm.reserved().end(); 1959 size_t granularity = HeapRegion::GrainBytes; 1960 1961 _in_cset_fast_test.initialize(start, end, granularity); 1962 _humongous_reclaim_candidates.initialize(start, end, granularity); 1963 } 1964 1965 // Create the G1ConcurrentMark data structure and thread. 1966 // (Must do this late, so that "max_regions" is defined.) 1967 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1968 if (_cm == NULL || !_cm->completed_initialization()) { 1969 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1970 return JNI_ENOMEM; 1971 } 1972 _cmThread = _cm->cmThread(); 1973 1974 // Now expand into the initial heap size. 1975 if (!expand(init_byte_size)) { 1976 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1977 return JNI_ENOMEM; 1978 } 1979 1980 // Perform any initialization actions delegated to the policy. 1981 g1_policy()->init(); 1982 1983 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 1984 SATB_Q_FL_lock, 1985 G1SATBProcessCompletedThreshold, 1986 Shared_SATB_Q_lock); 1987 1988 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 1989 DirtyCardQ_CBL_mon, 1990 DirtyCardQ_FL_lock, 1991 (int)concurrent_g1_refine()->yellow_zone(), 1992 (int)concurrent_g1_refine()->red_zone(), 1993 Shared_DirtyCardQ_lock, 1994 NULL, // fl_owner 1995 true); // init_free_ids 1996 1997 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 1998 DirtyCardQ_CBL_mon, 1999 DirtyCardQ_FL_lock, 2000 -1, // never trigger processing 2001 -1, // no limit on length 2002 Shared_DirtyCardQ_lock, 2003 &JavaThread::dirty_card_queue_set()); 2004 2005 // Here we allocate the dummy HeapRegion that is required by the 2006 // G1AllocRegion class. 2007 HeapRegion* dummy_region = _hrm.get_dummy_region(); 2008 2009 // We'll re-use the same region whether the alloc region will 2010 // require BOT updates or not and, if it doesn't, then a non-young 2011 // region will complain that it cannot support allocations without 2012 // BOT updates. So we'll tag the dummy region as eden to avoid that. 2013 dummy_region->set_eden(); 2014 // Make sure it's full. 2015 dummy_region->set_top(dummy_region->end()); 2016 G1AllocRegion::setup(this, dummy_region); 2017 2018 _allocator->init_mutator_alloc_region(); 2019 2020 // Do create of the monitoring and management support so that 2021 // values in the heap have been properly initialized. 2022 _g1mm = new G1MonitoringSupport(this); 2023 2024 G1StringDedup::initialize(); 2025 2026 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC); 2027 for (uint i = 0; i < ParallelGCThreads; i++) { 2028 new (&_preserved_objs[i]) OopAndMarkOopStack(); 2029 } 2030 2031 return JNI_OK; 2032 } 2033 2034 void G1CollectedHeap::stop() { 2035 // Stop all concurrent threads. We do this to make sure these threads 2036 // do not continue to execute and access resources (e.g. logging) 2037 // that are destroyed during shutdown. 2038 _cg1r->stop(); 2039 _cmThread->stop(); 2040 if (G1StringDedup::is_enabled()) { 2041 G1StringDedup::stop(); 2042 } 2043 } 2044 2045 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2046 return HeapRegion::max_region_size(); 2047 } 2048 2049 void G1CollectedHeap::post_initialize() { 2050 CollectedHeap::post_initialize(); 2051 ref_processing_init(); 2052 } 2053 2054 void G1CollectedHeap::ref_processing_init() { 2055 // Reference processing in G1 currently works as follows: 2056 // 2057 // * There are two reference processor instances. One is 2058 // used to record and process discovered references 2059 // during concurrent marking; the other is used to 2060 // record and process references during STW pauses 2061 // (both full and incremental). 2062 // * Both ref processors need to 'span' the entire heap as 2063 // the regions in the collection set may be dotted around. 2064 // 2065 // * For the concurrent marking ref processor: 2066 // * Reference discovery is enabled at initial marking. 2067 // * Reference discovery is disabled and the discovered 2068 // references processed etc during remarking. 2069 // * Reference discovery is MT (see below). 2070 // * Reference discovery requires a barrier (see below). 2071 // * Reference processing may or may not be MT 2072 // (depending on the value of ParallelRefProcEnabled 2073 // and ParallelGCThreads). 2074 // * A full GC disables reference discovery by the CM 2075 // ref processor and abandons any entries on it's 2076 // discovered lists. 2077 // 2078 // * For the STW processor: 2079 // * Non MT discovery is enabled at the start of a full GC. 2080 // * Processing and enqueueing during a full GC is non-MT. 2081 // * During a full GC, references are processed after marking. 2082 // 2083 // * Discovery (may or may not be MT) is enabled at the start 2084 // of an incremental evacuation pause. 2085 // * References are processed near the end of a STW evacuation pause. 2086 // * For both types of GC: 2087 // * Discovery is atomic - i.e. not concurrent. 2088 // * Reference discovery will not need a barrier. 2089 2090 MemRegion mr = reserved_region(); 2091 2092 // Concurrent Mark ref processor 2093 _ref_processor_cm = 2094 new ReferenceProcessor(mr, // span 2095 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2096 // mt processing 2097 ParallelGCThreads, 2098 // degree of mt processing 2099 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2100 // mt discovery 2101 MAX2(ParallelGCThreads, ConcGCThreads), 2102 // degree of mt discovery 2103 false, 2104 // Reference discovery is not atomic 2105 &_is_alive_closure_cm); 2106 // is alive closure 2107 // (for efficiency/performance) 2108 2109 // STW ref processor 2110 _ref_processor_stw = 2111 new ReferenceProcessor(mr, // span 2112 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2113 // mt processing 2114 ParallelGCThreads, 2115 // degree of mt processing 2116 (ParallelGCThreads > 1), 2117 // mt discovery 2118 ParallelGCThreads, 2119 // degree of mt discovery 2120 true, 2121 // Reference discovery is atomic 2122 &_is_alive_closure_stw); 2123 // is alive closure 2124 // (for efficiency/performance) 2125 } 2126 2127 CollectorPolicy* G1CollectedHeap::collector_policy() const { 2128 return g1_policy(); 2129 } 2130 2131 size_t G1CollectedHeap::capacity() const { 2132 return _hrm.length() * HeapRegion::GrainBytes; 2133 } 2134 2135 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2136 hr->reset_gc_time_stamp(); 2137 } 2138 2139 #ifndef PRODUCT 2140 2141 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2142 private: 2143 unsigned _gc_time_stamp; 2144 bool _failures; 2145 2146 public: 2147 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2148 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2149 2150 virtual bool doHeapRegion(HeapRegion* hr) { 2151 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2152 if (_gc_time_stamp != region_gc_time_stamp) { 2153 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr), 2154 region_gc_time_stamp, _gc_time_stamp); 2155 _failures = true; 2156 } 2157 return false; 2158 } 2159 2160 bool failures() { return _failures; } 2161 }; 2162 2163 void G1CollectedHeap::check_gc_time_stamps() { 2164 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2165 heap_region_iterate(&cl); 2166 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2167 } 2168 #endif // PRODUCT 2169 2170 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) { 2171 _cg1r->hot_card_cache()->drain(cl, worker_i); 2172 } 2173 2174 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) { 2175 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2176 size_t n_completed_buffers = 0; 2177 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2178 n_completed_buffers++; 2179 } 2180 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 2181 dcqs.clear_n_completed_buffers(); 2182 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2183 } 2184 2185 // Computes the sum of the storage used by the various regions. 2186 size_t G1CollectedHeap::used() const { 2187 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 2188 if (_archive_allocator != NULL) { 2189 result += _archive_allocator->used(); 2190 } 2191 return result; 2192 } 2193 2194 size_t G1CollectedHeap::used_unlocked() const { 2195 return _summary_bytes_used; 2196 } 2197 2198 class SumUsedClosure: public HeapRegionClosure { 2199 size_t _used; 2200 public: 2201 SumUsedClosure() : _used(0) {} 2202 bool doHeapRegion(HeapRegion* r) { 2203 _used += r->used(); 2204 return false; 2205 } 2206 size_t result() { return _used; } 2207 }; 2208 2209 size_t G1CollectedHeap::recalculate_used() const { 2210 double recalculate_used_start = os::elapsedTime(); 2211 2212 SumUsedClosure blk; 2213 heap_region_iterate(&blk); 2214 2215 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2216 return blk.result(); 2217 } 2218 2219 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 2220 switch (cause) { 2221 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2222 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 2223 case GCCause::_update_allocation_context_stats_inc: return true; 2224 case GCCause::_wb_conc_mark: return true; 2225 default : return false; 2226 } 2227 } 2228 2229 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2230 switch (cause) { 2231 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2232 case GCCause::_g1_humongous_allocation: return true; 2233 default: return is_user_requested_concurrent_full_gc(cause); 2234 } 2235 } 2236 2237 #ifndef PRODUCT 2238 void G1CollectedHeap::allocate_dummy_regions() { 2239 // Let's fill up most of the region 2240 size_t word_size = HeapRegion::GrainWords - 1024; 2241 // And as a result the region we'll allocate will be humongous. 2242 guarantee(is_humongous(word_size), "sanity"); 2243 2244 // _filler_array_max_size is set to humongous object threshold 2245 // but temporarily change it to use CollectedHeap::fill_with_object(). 2246 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2247 2248 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2249 // Let's use the existing mechanism for the allocation 2250 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2251 AllocationContext::system()); 2252 if (dummy_obj != NULL) { 2253 MemRegion mr(dummy_obj, word_size); 2254 CollectedHeap::fill_with_object(mr); 2255 } else { 2256 // If we can't allocate once, we probably cannot allocate 2257 // again. Let's get out of the loop. 2258 break; 2259 } 2260 } 2261 } 2262 #endif // !PRODUCT 2263 2264 void G1CollectedHeap::increment_old_marking_cycles_started() { 2265 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2266 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2267 "Wrong marking cycle count (started: %d, completed: %d)", 2268 _old_marking_cycles_started, _old_marking_cycles_completed); 2269 2270 _old_marking_cycles_started++; 2271 } 2272 2273 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2274 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2275 2276 // We assume that if concurrent == true, then the caller is a 2277 // concurrent thread that was joined the Suspendible Thread 2278 // Set. If there's ever a cheap way to check this, we should add an 2279 // assert here. 2280 2281 // Given that this method is called at the end of a Full GC or of a 2282 // concurrent cycle, and those can be nested (i.e., a Full GC can 2283 // interrupt a concurrent cycle), the number of full collections 2284 // completed should be either one (in the case where there was no 2285 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2286 // behind the number of full collections started. 2287 2288 // This is the case for the inner caller, i.e. a Full GC. 2289 assert(concurrent || 2290 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2291 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2292 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2293 "is inconsistent with _old_marking_cycles_completed = %u", 2294 _old_marking_cycles_started, _old_marking_cycles_completed); 2295 2296 // This is the case for the outer caller, i.e. the concurrent cycle. 2297 assert(!concurrent || 2298 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2299 "for outer caller (concurrent cycle): " 2300 "_old_marking_cycles_started = %u " 2301 "is inconsistent with _old_marking_cycles_completed = %u", 2302 _old_marking_cycles_started, _old_marking_cycles_completed); 2303 2304 _old_marking_cycles_completed += 1; 2305 2306 // We need to clear the "in_progress" flag in the CM thread before 2307 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2308 // is set) so that if a waiter requests another System.gc() it doesn't 2309 // incorrectly see that a marking cycle is still in progress. 2310 if (concurrent) { 2311 _cmThread->set_idle(); 2312 } 2313 2314 // This notify_all() will ensure that a thread that called 2315 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2316 // and it's waiting for a full GC to finish will be woken up. It is 2317 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2318 FullGCCount_lock->notify_all(); 2319 } 2320 2321 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2322 GCIdMarkAndRestore conc_gc_id_mark; 2323 collector_state()->set_concurrent_cycle_started(true); 2324 _gc_timer_cm->register_gc_start(start_time); 2325 2326 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2327 trace_heap_before_gc(_gc_tracer_cm); 2328 _cmThread->set_gc_id(GCId::current()); 2329 } 2330 2331 void G1CollectedHeap::register_concurrent_cycle_end() { 2332 if (collector_state()->concurrent_cycle_started()) { 2333 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id()); 2334 if (_cm->has_aborted()) { 2335 _gc_tracer_cm->report_concurrent_mode_failure(); 2336 2337 // ConcurrentGCTimer will be ended as well. 2338 _cm->register_concurrent_gc_end_and_stop_timer(); 2339 } else { 2340 _gc_timer_cm->register_gc_end(); 2341 } 2342 2343 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2344 2345 // Clear state variables to prepare for the next concurrent cycle. 2346 collector_state()->set_concurrent_cycle_started(false); 2347 _heap_summary_sent = false; 2348 } 2349 } 2350 2351 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2352 if (collector_state()->concurrent_cycle_started()) { 2353 // This function can be called when: 2354 // the cleanup pause is run 2355 // the concurrent cycle is aborted before the cleanup pause. 2356 // the concurrent cycle is aborted after the cleanup pause, 2357 // but before the concurrent cycle end has been registered. 2358 // Make sure that we only send the heap information once. 2359 if (!_heap_summary_sent) { 2360 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id()); 2361 trace_heap_after_gc(_gc_tracer_cm); 2362 _heap_summary_sent = true; 2363 } 2364 } 2365 } 2366 2367 void G1CollectedHeap::collect(GCCause::Cause cause) { 2368 assert_heap_not_locked(); 2369 2370 uint gc_count_before; 2371 uint old_marking_count_before; 2372 uint full_gc_count_before; 2373 bool retry_gc; 2374 2375 do { 2376 retry_gc = false; 2377 2378 { 2379 MutexLocker ml(Heap_lock); 2380 2381 // Read the GC count while holding the Heap_lock 2382 gc_count_before = total_collections(); 2383 full_gc_count_before = total_full_collections(); 2384 old_marking_count_before = _old_marking_cycles_started; 2385 } 2386 2387 if (should_do_concurrent_full_gc(cause)) { 2388 // Schedule an initial-mark evacuation pause that will start a 2389 // concurrent cycle. We're setting word_size to 0 which means that 2390 // we are not requesting a post-GC allocation. 2391 VM_G1IncCollectionPause op(gc_count_before, 2392 0, /* word_size */ 2393 true, /* should_initiate_conc_mark */ 2394 g1_policy()->max_pause_time_ms(), 2395 cause); 2396 op.set_allocation_context(AllocationContext::current()); 2397 2398 VMThread::execute(&op); 2399 if (!op.pause_succeeded()) { 2400 if (old_marking_count_before == _old_marking_cycles_started) { 2401 retry_gc = op.should_retry_gc(); 2402 } else { 2403 // A Full GC happened while we were trying to schedule the 2404 // initial-mark GC. No point in starting a new cycle given 2405 // that the whole heap was collected anyway. 2406 } 2407 2408 if (retry_gc) { 2409 if (GCLocker::is_active_and_needs_gc()) { 2410 GCLocker::stall_until_clear(); 2411 } 2412 } 2413 } 2414 } else { 2415 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2416 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2417 2418 // Schedule a standard evacuation pause. We're setting word_size 2419 // to 0 which means that we are not requesting a post-GC allocation. 2420 VM_G1IncCollectionPause op(gc_count_before, 2421 0, /* word_size */ 2422 false, /* should_initiate_conc_mark */ 2423 g1_policy()->max_pause_time_ms(), 2424 cause); 2425 VMThread::execute(&op); 2426 } else { 2427 // Schedule a Full GC. 2428 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2429 VMThread::execute(&op); 2430 } 2431 } 2432 } while (retry_gc); 2433 } 2434 2435 bool G1CollectedHeap::is_in(const void* p) const { 2436 if (_hrm.reserved().contains(p)) { 2437 // Given that we know that p is in the reserved space, 2438 // heap_region_containing() should successfully 2439 // return the containing region. 2440 HeapRegion* hr = heap_region_containing(p); 2441 return hr->is_in(p); 2442 } else { 2443 return false; 2444 } 2445 } 2446 2447 #ifdef ASSERT 2448 bool G1CollectedHeap::is_in_exact(const void* p) const { 2449 bool contains = reserved_region().contains(p); 2450 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2451 if (contains && available) { 2452 return true; 2453 } else { 2454 return false; 2455 } 2456 } 2457 #endif 2458 2459 bool G1CollectedHeap::obj_in_cs(oop obj) { 2460 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj); 2461 return r != NULL && r->in_collection_set(); 2462 } 2463 2464 // Iteration functions. 2465 2466 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2467 2468 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2469 ExtendedOopClosure* _cl; 2470 public: 2471 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2472 bool doHeapRegion(HeapRegion* r) { 2473 if (!r->is_continues_humongous()) { 2474 r->oop_iterate(_cl); 2475 } 2476 return false; 2477 } 2478 }; 2479 2480 // Iterates an ObjectClosure over all objects within a HeapRegion. 2481 2482 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2483 ObjectClosure* _cl; 2484 public: 2485 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2486 bool doHeapRegion(HeapRegion* r) { 2487 if (!r->is_continues_humongous()) { 2488 r->object_iterate(_cl); 2489 } 2490 return false; 2491 } 2492 }; 2493 2494 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2495 IterateObjectClosureRegionClosure blk(cl); 2496 heap_region_iterate(&blk); 2497 } 2498 2499 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2500 _hrm.iterate(cl); 2501 } 2502 2503 void 2504 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, 2505 uint worker_id, 2506 HeapRegionClaimer *hrclaimer, 2507 bool concurrent) const { 2508 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); 2509 } 2510 2511 // Clear the cached CSet starting regions and (more importantly) 2512 // the time stamps. Called when we reset the GC time stamp. 2513 void G1CollectedHeap::clear_cset_start_regions() { 2514 assert(_worker_cset_start_region != NULL, "sanity"); 2515 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2516 2517 for (uint i = 0; i < ParallelGCThreads; i++) { 2518 _worker_cset_start_region[i] = NULL; 2519 _worker_cset_start_region_time_stamp[i] = 0; 2520 } 2521 } 2522 2523 // Given the id of a worker, obtain or calculate a suitable 2524 // starting region for iterating over the current collection set. 2525 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2526 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2527 2528 HeapRegion* result = NULL; 2529 unsigned gc_time_stamp = get_gc_time_stamp(); 2530 2531 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2532 // Cached starting region for current worker was set 2533 // during the current pause - so it's valid. 2534 // Note: the cached starting heap region may be NULL 2535 // (when the collection set is empty). 2536 result = _worker_cset_start_region[worker_i]; 2537 assert(result == NULL || result->in_collection_set(), "sanity"); 2538 return result; 2539 } 2540 2541 // The cached entry was not valid so let's calculate 2542 // a suitable starting heap region for this worker. 2543 2544 // We want the parallel threads to start their collection 2545 // set iteration at different collection set regions to 2546 // avoid contention. 2547 // If we have: 2548 // n collection set regions 2549 // p threads 2550 // Then thread t will start at region floor ((t * n) / p) 2551 2552 result = collection_set()->head(); 2553 uint cs_size = collection_set()->region_length(); 2554 uint active_workers = workers()->active_workers(); 2555 2556 uint end_ind = (cs_size * worker_i) / active_workers; 2557 uint start_ind = 0; 2558 2559 if (worker_i > 0 && 2560 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2561 // Previous workers starting region is valid 2562 // so let's iterate from there 2563 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2564 OrderAccess::loadload(); 2565 result = _worker_cset_start_region[worker_i - 1]; 2566 } 2567 2568 for (uint i = start_ind; i < end_ind; i++) { 2569 result = result->next_in_collection_set(); 2570 } 2571 2572 // Note: the calculated starting heap region may be NULL 2573 // (when the collection set is empty). 2574 assert(result == NULL || result->in_collection_set(), "sanity"); 2575 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2576 "should be updated only once per pause"); 2577 _worker_cset_start_region[worker_i] = result; 2578 OrderAccess::storestore(); 2579 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2580 return result; 2581 } 2582 2583 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2584 HeapRegion* r = collection_set()->head(); 2585 while (r != NULL) { 2586 HeapRegion* next = r->next_in_collection_set(); 2587 if (cl->doHeapRegion(r)) { 2588 cl->incomplete(); 2589 return; 2590 } 2591 r = next; 2592 } 2593 } 2594 2595 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2596 HeapRegionClosure *cl) { 2597 if (r == NULL) { 2598 // The CSet is empty so there's nothing to do. 2599 return; 2600 } 2601 2602 assert(r->in_collection_set(), 2603 "Start region must be a member of the collection set."); 2604 HeapRegion* cur = r; 2605 while (cur != NULL) { 2606 HeapRegion* next = cur->next_in_collection_set(); 2607 if (cl->doHeapRegion(cur) && false) { 2608 cl->incomplete(); 2609 return; 2610 } 2611 cur = next; 2612 } 2613 cur = collection_set()->head(); 2614 while (cur != r) { 2615 HeapRegion* next = cur->next_in_collection_set(); 2616 if (cl->doHeapRegion(cur) && false) { 2617 cl->incomplete(); 2618 return; 2619 } 2620 cur = next; 2621 } 2622 } 2623 2624 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2625 HeapRegion* result = _hrm.next_region_in_heap(from); 2626 while (result != NULL && result->is_pinned()) { 2627 result = _hrm.next_region_in_heap(result); 2628 } 2629 return result; 2630 } 2631 2632 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2633 HeapRegion* hr = heap_region_containing(addr); 2634 return hr->block_start(addr); 2635 } 2636 2637 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2638 HeapRegion* hr = heap_region_containing(addr); 2639 return hr->block_size(addr); 2640 } 2641 2642 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2643 HeapRegion* hr = heap_region_containing(addr); 2644 return hr->block_is_obj(addr); 2645 } 2646 2647 bool G1CollectedHeap::supports_tlab_allocation() const { 2648 return true; 2649 } 2650 2651 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2652 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2653 } 2654 2655 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2656 return young_list()->eden_used_bytes(); 2657 } 2658 2659 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2660 // must be equal to the humongous object limit. 2661 size_t G1CollectedHeap::max_tlab_size() const { 2662 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment); 2663 } 2664 2665 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2666 AllocationContext_t context = AllocationContext::current(); 2667 return _allocator->unsafe_max_tlab_alloc(context); 2668 } 2669 2670 size_t G1CollectedHeap::max_capacity() const { 2671 return _hrm.reserved().byte_size(); 2672 } 2673 2674 jlong G1CollectedHeap::millis_since_last_gc() { 2675 // assert(false, "NYI"); 2676 return 0; 2677 } 2678 2679 void G1CollectedHeap::prepare_for_verify() { 2680 _verifier->prepare_for_verify(); 2681 } 2682 2683 void G1CollectedHeap::verify(VerifyOption vo) { 2684 _verifier->verify(vo); 2685 } 2686 2687 class PrintRegionClosure: public HeapRegionClosure { 2688 outputStream* _st; 2689 public: 2690 PrintRegionClosure(outputStream* st) : _st(st) {} 2691 bool doHeapRegion(HeapRegion* r) { 2692 r->print_on(_st); 2693 return false; 2694 } 2695 }; 2696 2697 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2698 const HeapRegion* hr, 2699 const VerifyOption vo) const { 2700 switch (vo) { 2701 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2702 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2703 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive(); 2704 default: ShouldNotReachHere(); 2705 } 2706 return false; // keep some compilers happy 2707 } 2708 2709 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2710 const VerifyOption vo) const { 2711 switch (vo) { 2712 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2713 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2714 case VerifyOption_G1UseMarkWord: { 2715 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj); 2716 return !obj->is_gc_marked() && !hr->is_archive(); 2717 } 2718 default: ShouldNotReachHere(); 2719 } 2720 return false; // keep some compilers happy 2721 } 2722 2723 void G1CollectedHeap::print_heap_regions() const { 2724 LogHandle(gc, heap, region) log; 2725 if (log.is_trace()) { 2726 ResourceMark rm; 2727 print_regions_on(log.trace_stream()); 2728 } 2729 } 2730 2731 void G1CollectedHeap::print_on(outputStream* st) const { 2732 st->print(" %-20s", "garbage-first heap"); 2733 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2734 capacity()/K, used_unlocked()/K); 2735 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")", 2736 p2i(_hrm.reserved().start()), 2737 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords), 2738 p2i(_hrm.reserved().end())); 2739 st->cr(); 2740 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2741 uint young_regions = _young_list->length(); 2742 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2743 (size_t) young_regions * HeapRegion::GrainBytes / K); 2744 uint survivor_regions = _young_list->survivor_length(); 2745 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2746 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2747 st->cr(); 2748 MetaspaceAux::print_on(st); 2749 } 2750 2751 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2752 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2753 "HS=humongous(starts), HC=humongous(continues), " 2754 "CS=collection set, F=free, A=archive, TS=gc time stamp, " 2755 "AC=allocation context, " 2756 "TAMS=top-at-mark-start (previous, next)"); 2757 PrintRegionClosure blk(st); 2758 heap_region_iterate(&blk); 2759 } 2760 2761 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2762 print_on(st); 2763 2764 // Print the per-region information. 2765 print_regions_on(st); 2766 } 2767 2768 void G1CollectedHeap::print_on_error(outputStream* st) const { 2769 this->CollectedHeap::print_on_error(st); 2770 2771 if (_cm != NULL) { 2772 st->cr(); 2773 _cm->print_on_error(st); 2774 } 2775 } 2776 2777 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2778 workers()->print_worker_threads_on(st); 2779 _cmThread->print_on(st); 2780 st->cr(); 2781 _cm->print_worker_threads_on(st); 2782 _cg1r->print_worker_threads_on(st); 2783 if (G1StringDedup::is_enabled()) { 2784 G1StringDedup::print_worker_threads_on(st); 2785 } 2786 } 2787 2788 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2789 workers()->threads_do(tc); 2790 tc->do_thread(_cmThread); 2791 _cg1r->threads_do(tc); 2792 if (G1StringDedup::is_enabled()) { 2793 G1StringDedup::threads_do(tc); 2794 } 2795 } 2796 2797 void G1CollectedHeap::print_tracing_info() const { 2798 g1_rem_set()->print_summary_info(); 2799 concurrent_mark()->print_summary_info(); 2800 g1_policy()->print_yg_surv_rate_info(); 2801 } 2802 2803 #ifndef PRODUCT 2804 // Helpful for debugging RSet issues. 2805 2806 class PrintRSetsClosure : public HeapRegionClosure { 2807 private: 2808 const char* _msg; 2809 size_t _occupied_sum; 2810 2811 public: 2812 bool doHeapRegion(HeapRegion* r) { 2813 HeapRegionRemSet* hrrs = r->rem_set(); 2814 size_t occupied = hrrs->occupied(); 2815 _occupied_sum += occupied; 2816 2817 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2818 if (occupied == 0) { 2819 tty->print_cr(" RSet is empty"); 2820 } else { 2821 hrrs->print(); 2822 } 2823 tty->print_cr("----------"); 2824 return false; 2825 } 2826 2827 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2828 tty->cr(); 2829 tty->print_cr("========================================"); 2830 tty->print_cr("%s", msg); 2831 tty->cr(); 2832 } 2833 2834 ~PrintRSetsClosure() { 2835 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2836 tty->print_cr("========================================"); 2837 tty->cr(); 2838 } 2839 }; 2840 2841 void G1CollectedHeap::print_cset_rsets() { 2842 PrintRSetsClosure cl("Printing CSet RSets"); 2843 collection_set_iterate(&cl); 2844 } 2845 2846 void G1CollectedHeap::print_all_rsets() { 2847 PrintRSetsClosure cl("Printing All RSets");; 2848 heap_region_iterate(&cl); 2849 } 2850 #endif // PRODUCT 2851 2852 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2853 YoungList* young_list = heap()->young_list(); 2854 2855 size_t eden_used_bytes = young_list->eden_used_bytes(); 2856 size_t survivor_used_bytes = young_list->survivor_used_bytes(); 2857 2858 size_t eden_capacity_bytes = 2859 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2860 2861 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2862 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes, num_regions()); 2863 } 2864 2865 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2866 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2867 stats->unused(), stats->used(), stats->region_end_waste(), 2868 stats->regions_filled(), stats->direct_allocated(), 2869 stats->failure_used(), stats->failure_waste()); 2870 } 2871 2872 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2873 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2874 gc_tracer->report_gc_heap_summary(when, heap_summary); 2875 2876 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2877 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2878 } 2879 2880 2881 G1CollectedHeap* G1CollectedHeap::heap() { 2882 CollectedHeap* heap = Universe::heap(); 2883 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2884 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); 2885 return (G1CollectedHeap*)heap; 2886 } 2887 2888 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 2889 // always_do_update_barrier = false; 2890 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2891 // Fill TLAB's and such 2892 accumulate_statistics_all_tlabs(); 2893 ensure_parsability(true); 2894 2895 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2896 } 2897 2898 void G1CollectedHeap::gc_epilogue(bool full) { 2899 // we are at the end of the GC. Total collections has already been increased. 2900 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2901 2902 // FIXME: what is this about? 2903 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2904 // is set. 2905 #if defined(COMPILER2) || INCLUDE_JVMCI 2906 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2907 #endif 2908 // always_do_update_barrier = true; 2909 2910 resize_all_tlabs(); 2911 allocation_context_stats().update(full); 2912 2913 // We have just completed a GC. Update the soft reference 2914 // policy with the new heap occupancy 2915 Universe::update_heap_info_at_gc(); 2916 } 2917 2918 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2919 uint gc_count_before, 2920 bool* succeeded, 2921 GCCause::Cause gc_cause) { 2922 assert_heap_not_locked_and_not_at_safepoint(); 2923 VM_G1IncCollectionPause op(gc_count_before, 2924 word_size, 2925 false, /* should_initiate_conc_mark */ 2926 g1_policy()->max_pause_time_ms(), 2927 gc_cause); 2928 2929 op.set_allocation_context(AllocationContext::current()); 2930 VMThread::execute(&op); 2931 2932 HeapWord* result = op.result(); 2933 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 2934 assert(result == NULL || ret_succeeded, 2935 "the result should be NULL if the VM did not succeed"); 2936 *succeeded = ret_succeeded; 2937 2938 assert_heap_not_locked(); 2939 return result; 2940 } 2941 2942 void 2943 G1CollectedHeap::doConcurrentMark() { 2944 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 2945 if (!_cmThread->in_progress()) { 2946 _cmThread->set_started(); 2947 CGC_lock->notify(); 2948 } 2949 } 2950 2951 size_t G1CollectedHeap::pending_card_num() { 2952 size_t extra_cards = 0; 2953 JavaThread *curr = Threads::first(); 2954 while (curr != NULL) { 2955 DirtyCardQueue& dcq = curr->dirty_card_queue(); 2956 extra_cards += dcq.size(); 2957 curr = curr->next(); 2958 } 2959 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2960 size_t buffer_size = dcqs.buffer_size(); 2961 size_t buffer_num = dcqs.completed_buffers_num(); 2962 2963 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 2964 // in bytes - not the number of 'entries'. We need to convert 2965 // into a number of cards. 2966 return (buffer_size * buffer_num + extra_cards) / oopSize; 2967 } 2968 2969 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 2970 private: 2971 size_t _total_humongous; 2972 size_t _candidate_humongous; 2973 2974 DirtyCardQueue _dcq; 2975 2976 // We don't nominate objects with many remembered set entries, on 2977 // the assumption that such objects are likely still live. 2978 bool is_remset_small(HeapRegion* region) const { 2979 HeapRegionRemSet* const rset = region->rem_set(); 2980 return G1EagerReclaimHumongousObjectsWithStaleRefs 2981 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) 2982 : rset->is_empty(); 2983 } 2984 2985 bool is_typeArray_region(HeapRegion* region) const { 2986 return oop(region->bottom())->is_typeArray(); 2987 } 2988 2989 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { 2990 assert(region->is_starts_humongous(), "Must start a humongous object"); 2991 2992 // Candidate selection must satisfy the following constraints 2993 // while concurrent marking is in progress: 2994 // 2995 // * In order to maintain SATB invariants, an object must not be 2996 // reclaimed if it was allocated before the start of marking and 2997 // has not had its references scanned. Such an object must have 2998 // its references (including type metadata) scanned to ensure no 2999 // live objects are missed by the marking process. Objects 3000 // allocated after the start of concurrent marking don't need to 3001 // be scanned. 3002 // 3003 // * An object must not be reclaimed if it is on the concurrent 3004 // mark stack. Objects allocated after the start of concurrent 3005 // marking are never pushed on the mark stack. 3006 // 3007 // Nominating only objects allocated after the start of concurrent 3008 // marking is sufficient to meet both constraints. This may miss 3009 // some objects that satisfy the constraints, but the marking data 3010 // structures don't support efficiently performing the needed 3011 // additional tests or scrubbing of the mark stack. 3012 // 3013 // However, we presently only nominate is_typeArray() objects. 3014 // A humongous object containing references induces remembered 3015 // set entries on other regions. In order to reclaim such an 3016 // object, those remembered sets would need to be cleaned up. 3017 // 3018 // We also treat is_typeArray() objects specially, allowing them 3019 // to be reclaimed even if allocated before the start of 3020 // concurrent mark. For this we rely on mark stack insertion to 3021 // exclude is_typeArray() objects, preventing reclaiming an object 3022 // that is in the mark stack. We also rely on the metadata for 3023 // such objects to be built-in and so ensured to be kept live. 3024 // Frequent allocation and drop of large binary blobs is an 3025 // important use case for eager reclaim, and this special handling 3026 // may reduce needed headroom. 3027 3028 return is_typeArray_region(region) && is_remset_small(region); 3029 } 3030 3031 public: 3032 RegisterHumongousWithInCSetFastTestClosure() 3033 : _total_humongous(0), 3034 _candidate_humongous(0), 3035 _dcq(&JavaThread::dirty_card_queue_set()) { 3036 } 3037 3038 virtual bool doHeapRegion(HeapRegion* r) { 3039 if (!r->is_starts_humongous()) { 3040 return false; 3041 } 3042 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3043 3044 bool is_candidate = humongous_region_is_candidate(g1h, r); 3045 uint rindex = r->hrm_index(); 3046 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 3047 if (is_candidate) { 3048 _candidate_humongous++; 3049 g1h->register_humongous_region_with_cset(rindex); 3050 // Is_candidate already filters out humongous object with large remembered sets. 3051 // If we have a humongous object with a few remembered sets, we simply flush these 3052 // remembered set entries into the DCQS. That will result in automatic 3053 // re-evaluation of their remembered set entries during the following evacuation 3054 // phase. 3055 if (!r->rem_set()->is_empty()) { 3056 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 3057 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 3058 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 3059 HeapRegionRemSetIterator hrrs(r->rem_set()); 3060 size_t card_index; 3061 while (hrrs.has_next(card_index)) { 3062 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 3063 // The remembered set might contain references to already freed 3064 // regions. Filter out such entries to avoid failing card table 3065 // verification. 3066 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) { 3067 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 3068 *card_ptr = CardTableModRefBS::dirty_card_val(); 3069 _dcq.enqueue(card_ptr); 3070 } 3071 } 3072 } 3073 assert(hrrs.n_yielded() == r->rem_set()->occupied(), 3074 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", 3075 hrrs.n_yielded(), r->rem_set()->occupied()); 3076 r->rem_set()->clear_locked(); 3077 } 3078 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 3079 } 3080 _total_humongous++; 3081 3082 return false; 3083 } 3084 3085 size_t total_humongous() const { return _total_humongous; } 3086 size_t candidate_humongous() const { return _candidate_humongous; } 3087 3088 void flush_rem_set_entries() { _dcq.flush(); } 3089 }; 3090 3091 void G1CollectedHeap::register_humongous_regions_with_cset() { 3092 if (!G1EagerReclaimHumongousObjects) { 3093 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 3094 return; 3095 } 3096 double time = os::elapsed_counter(); 3097 3098 // Collect reclaim candidate information and register candidates with cset. 3099 RegisterHumongousWithInCSetFastTestClosure cl; 3100 heap_region_iterate(&cl); 3101 3102 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 3103 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 3104 cl.total_humongous(), 3105 cl.candidate_humongous()); 3106 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3107 3108 // Finally flush all remembered set entries to re-check into the global DCQS. 3109 cl.flush_rem_set_entries(); 3110 } 3111 3112 class VerifyRegionRemSetClosure : public HeapRegionClosure { 3113 public: 3114 bool doHeapRegion(HeapRegion* hr) { 3115 if (!hr->is_archive() && !hr->is_continues_humongous()) { 3116 hr->verify_rem_set(); 3117 } 3118 return false; 3119 } 3120 }; 3121 3122 #ifdef ASSERT 3123 class VerifyCSetClosure: public HeapRegionClosure { 3124 public: 3125 bool doHeapRegion(HeapRegion* hr) { 3126 // Here we check that the CSet region's RSet is ready for parallel 3127 // iteration. The fields that we'll verify are only manipulated 3128 // when the region is part of a CSet and is collected. Afterwards, 3129 // we reset these fields when we clear the region's RSet (when the 3130 // region is freed) so they are ready when the region is 3131 // re-allocated. The only exception to this is if there's an 3132 // evacuation failure and instead of freeing the region we leave 3133 // it in the heap. In that case, we reset these fields during 3134 // evacuation failure handling. 3135 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3136 3137 // Here's a good place to add any other checks we'd like to 3138 // perform on CSet regions. 3139 return false; 3140 } 3141 }; 3142 #endif // ASSERT 3143 3144 uint G1CollectedHeap::num_task_queues() const { 3145 return _task_queues->size(); 3146 } 3147 3148 #if TASKQUEUE_STATS 3149 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3150 st->print_raw_cr("GC Task Stats"); 3151 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3152 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3153 } 3154 3155 void G1CollectedHeap::print_taskqueue_stats() const { 3156 if (!log_develop_is_enabled(Trace, gc, task, stats)) { 3157 return; 3158 } 3159 LogHandle(gc, task, stats) log; 3160 ResourceMark rm; 3161 outputStream* st = log.trace_stream(); 3162 3163 print_taskqueue_stats_hdr(st); 3164 3165 TaskQueueStats totals; 3166 const uint n = num_task_queues(); 3167 for (uint i = 0; i < n; ++i) { 3168 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 3169 totals += task_queue(i)->stats; 3170 } 3171 st->print_raw("tot "); totals.print(st); st->cr(); 3172 3173 DEBUG_ONLY(totals.verify()); 3174 } 3175 3176 void G1CollectedHeap::reset_taskqueue_stats() { 3177 const uint n = num_task_queues(); 3178 for (uint i = 0; i < n; ++i) { 3179 task_queue(i)->stats.reset(); 3180 } 3181 } 3182 #endif // TASKQUEUE_STATS 3183 3184 void G1CollectedHeap::wait_for_root_region_scanning() { 3185 double scan_wait_start = os::elapsedTime(); 3186 // We have to wait until the CM threads finish scanning the 3187 // root regions as it's the only way to ensure that all the 3188 // objects on them have been correctly scanned before we start 3189 // moving them during the GC. 3190 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3191 double wait_time_ms = 0.0; 3192 if (waited) { 3193 double scan_wait_end = os::elapsedTime(); 3194 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3195 } 3196 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3197 } 3198 3199 bool 3200 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3201 assert_at_safepoint(true /* should_be_vm_thread */); 3202 guarantee(!is_gc_active(), "collection is not reentrant"); 3203 3204 if (GCLocker::check_active_before_gc()) { 3205 return false; 3206 } 3207 3208 _gc_timer_stw->register_gc_start(); 3209 3210 GCIdMark gc_id_mark; 3211 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3212 3213 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3214 ResourceMark rm; 3215 3216 wait_for_root_region_scanning(); 3217 3218 print_heap_before_gc(); 3219 print_heap_regions(); 3220 trace_heap_before_gc(_gc_tracer_stw); 3221 3222 _verifier->verify_region_sets_optional(); 3223 _verifier->verify_dirty_young_regions(); 3224 3225 // This call will decide whether this pause is an initial-mark 3226 // pause. If it is, during_initial_mark_pause() will return true 3227 // for the duration of this pause. 3228 g1_policy()->decide_on_conc_mark_initiation(); 3229 3230 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3231 assert(!collector_state()->during_initial_mark_pause() || 3232 collector_state()->gcs_are_young(), "sanity"); 3233 3234 // We also do not allow mixed GCs during marking. 3235 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity"); 3236 3237 // Record whether this pause is an initial mark. When the current 3238 // thread has completed its logging output and it's safe to signal 3239 // the CM thread, the flag's value in the policy has been reset. 3240 bool should_start_conc_mark = collector_state()->during_initial_mark_pause(); 3241 3242 // Inner scope for scope based logging, timers, and stats collection 3243 { 3244 EvacuationInfo evacuation_info; 3245 3246 if (collector_state()->during_initial_mark_pause()) { 3247 // We are about to start a marking cycle, so we increment the 3248 // full collection counter. 3249 increment_old_marking_cycles_started(); 3250 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3251 } 3252 3253 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 3254 3255 GCTraceCPUTime tcpu; 3256 3257 FormatBuffer<> gc_string("Pause "); 3258 if (collector_state()->during_initial_mark_pause()) { 3259 gc_string.append("Initial Mark"); 3260 } else if (collector_state()->gcs_are_young()) { 3261 gc_string.append("Young"); 3262 } else { 3263 gc_string.append("Mixed"); 3264 } 3265 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true); 3266 3267 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 3268 workers()->active_workers(), 3269 Threads::number_of_non_daemon_threads()); 3270 workers()->set_active_workers(active_workers); 3271 3272 g1_policy()->note_gc_start(active_workers); 3273 3274 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3275 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3276 3277 // If the secondary_free_list is not empty, append it to the 3278 // free_list. No need to wait for the cleanup operation to finish; 3279 // the region allocation code will check the secondary_free_list 3280 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3281 // set, skip this step so that the region allocation code has to 3282 // get entries from the secondary_free_list. 3283 if (!G1StressConcRegionFreeing) { 3284 append_secondary_free_list_if_not_empty_with_lock(); 3285 } 3286 3287 G1HeapTransition heap_transition(this); 3288 size_t heap_used_bytes_before_gc = used(); 3289 3290 assert(check_young_list_well_formed(), "young list should be well formed"); 3291 3292 // Don't dynamically change the number of GC threads this early. A value of 3293 // 0 is used to indicate serial work. When parallel work is done, 3294 // it will be set. 3295 3296 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3297 IsGCActiveMark x; 3298 3299 gc_prologue(false); 3300 increment_total_collections(false /* full gc */); 3301 increment_gc_time_stamp(); 3302 3303 if (VerifyRememberedSets) { 3304 log_info(gc, verify)("[Verifying RemSets before GC]"); 3305 VerifyRegionRemSetClosure v_cl; 3306 heap_region_iterate(&v_cl); 3307 } 3308 3309 _verifier->verify_before_gc(); 3310 3311 _verifier->check_bitmaps("GC Start"); 3312 3313 #if defined(COMPILER2) || INCLUDE_JVMCI 3314 DerivedPointerTable::clear(); 3315 #endif 3316 3317 // Please see comment in g1CollectedHeap.hpp and 3318 // G1CollectedHeap::ref_processing_init() to see how 3319 // reference processing currently works in G1. 3320 3321 // Enable discovery in the STW reference processor 3322 if (g1_policy()->should_process_references()) { 3323 ref_processor_stw()->enable_discovery(); 3324 } else { 3325 ref_processor_stw()->disable_discovery(); 3326 } 3327 3328 { 3329 // We want to temporarily turn off discovery by the 3330 // CM ref processor, if necessary, and turn it back on 3331 // on again later if we do. Using a scoped 3332 // NoRefDiscovery object will do this. 3333 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3334 3335 // Forget the current alloc region (we might even choose it to be part 3336 // of the collection set!). 3337 _allocator->release_mutator_alloc_region(); 3338 3339 // This timing is only used by the ergonomics to handle our pause target. 3340 // It is unclear why this should not include the full pause. We will 3341 // investigate this in CR 7178365. 3342 // 3343 // Preserving the old comment here if that helps the investigation: 3344 // 3345 // The elapsed time induced by the start time below deliberately elides 3346 // the possible verification above. 3347 double sample_start_time_sec = os::elapsedTime(); 3348 3349 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3350 3351 if (collector_state()->during_initial_mark_pause()) { 3352 concurrent_mark()->checkpointRootsInitialPre(); 3353 } 3354 3355 g1_policy()->finalize_collection_set(target_pause_time_ms); 3356 3357 evacuation_info.set_collectionset_regions(collection_set()->region_length()); 3358 3359 // Make sure the remembered sets are up to date. This needs to be 3360 // done before register_humongous_regions_with_cset(), because the 3361 // remembered sets are used there to choose eager reclaim candidates. 3362 // If the remembered sets are not up to date we might miss some 3363 // entries that need to be handled. 3364 g1_rem_set()->cleanupHRRS(); 3365 3366 register_humongous_regions_with_cset(); 3367 3368 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3369 3370 _cm->note_start_of_gc(); 3371 // We call this after finalize_cset() to 3372 // ensure that the CSet has been finalized. 3373 _cm->verify_no_cset_oops(); 3374 3375 if (_hr_printer.is_active()) { 3376 HeapRegion* hr = collection_set()->head(); 3377 while (hr != NULL) { 3378 _hr_printer.cset(hr); 3379 hr = hr->next_in_collection_set(); 3380 } 3381 } 3382 3383 #ifdef ASSERT 3384 VerifyCSetClosure cl; 3385 collection_set_iterate(&cl); 3386 #endif // ASSERT 3387 3388 // Initialize the GC alloc regions. 3389 _allocator->init_gc_alloc_regions(evacuation_info); 3390 3391 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length()); 3392 pre_evacuate_collection_set(); 3393 3394 // Actually do the work... 3395 evacuate_collection_set(evacuation_info, &per_thread_states); 3396 3397 post_evacuate_collection_set(evacuation_info, &per_thread_states); 3398 3399 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 3400 free_collection_set(collection_set()->head(), evacuation_info, surviving_young_words); 3401 3402 eagerly_reclaim_humongous_regions(); 3403 3404 collection_set()->clear_head(); 3405 3406 record_obj_copy_mem_stats(); 3407 _survivor_evac_stats.adjust_desired_plab_sz(); 3408 _old_evac_stats.adjust_desired_plab_sz(); 3409 3410 // Start a new incremental collection set for the next pause. 3411 collection_set()->start_incremental_building(); 3412 3413 clear_cset_fast_test(); 3414 3415 // Don't check the whole heap at this point as the 3416 // GC alloc regions from this pause have been tagged 3417 // as survivors and moved on to the survivor list. 3418 // Survivor regions will fail the !is_young() check. 3419 assert(check_young_list_empty(false /* check_heap */), 3420 "young list should be empty"); 3421 3422 _young_list->reset_auxilary_lists(); 3423 3424 if (evacuation_failed()) { 3425 set_used(recalculate_used()); 3426 if (_archive_allocator != NULL) { 3427 _archive_allocator->clear_used(); 3428 } 3429 for (uint i = 0; i < ParallelGCThreads; i++) { 3430 if (_evacuation_failed_info_array[i].has_failed()) { 3431 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3432 } 3433 } 3434 } else { 3435 // The "used" of the the collection set have already been subtracted 3436 // when they were freed. Add in the bytes evacuated. 3437 increase_used(g1_policy()->bytes_copied_during_gc()); 3438 } 3439 3440 if (collector_state()->during_initial_mark_pause()) { 3441 // We have to do this before we notify the CM threads that 3442 // they can start working to make sure that all the 3443 // appropriate initialization is done on the CM object. 3444 concurrent_mark()->checkpointRootsInitialPost(); 3445 collector_state()->set_mark_in_progress(true); 3446 // Note that we don't actually trigger the CM thread at 3447 // this point. We do that later when we're sure that 3448 // the current thread has completed its logging output. 3449 } 3450 3451 allocate_dummy_regions(); 3452 3453 _allocator->init_mutator_alloc_region(); 3454 3455 { 3456 size_t expand_bytes = g1_policy()->expansion_amount(); 3457 if (expand_bytes > 0) { 3458 size_t bytes_before = capacity(); 3459 // No need for an ergo logging here, 3460 // expansion_amount() does this when it returns a value > 0. 3461 double expand_ms; 3462 if (!expand(expand_bytes, &expand_ms)) { 3463 // We failed to expand the heap. Cannot do anything about it. 3464 } 3465 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 3466 } 3467 } 3468 3469 // We redo the verification but now wrt to the new CSet which 3470 // has just got initialized after the previous CSet was freed. 3471 _cm->verify_no_cset_oops(); 3472 _cm->note_end_of_gc(); 3473 3474 // This timing is only used by the ergonomics to handle our pause target. 3475 // It is unclear why this should not include the full pause. We will 3476 // investigate this in CR 7178365. 3477 double sample_end_time_sec = os::elapsedTime(); 3478 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3479 size_t total_cards_scanned = per_thread_states.total_cards_scanned(); 3480 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc); 3481 3482 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3483 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 3484 3485 MemoryService::track_memory_usage(); 3486 3487 // In prepare_for_verify() below we'll need to scan the deferred 3488 // update buffers to bring the RSets up-to-date if 3489 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 3490 // the update buffers we'll probably need to scan cards on the 3491 // regions we just allocated to (i.e., the GC alloc 3492 // regions). However, during the last GC we called 3493 // set_saved_mark() on all the GC alloc regions, so card 3494 // scanning might skip the [saved_mark_word()...top()] area of 3495 // those regions (i.e., the area we allocated objects into 3496 // during the last GC). But it shouldn't. Given that 3497 // saved_mark_word() is conditional on whether the GC time stamp 3498 // on the region is current or not, by incrementing the GC time 3499 // stamp here we invalidate all the GC time stamps on all the 3500 // regions and saved_mark_word() will simply return top() for 3501 // all the regions. This is a nicer way of ensuring this rather 3502 // than iterating over the regions and fixing them. In fact, the 3503 // GC time stamp increment here also ensures that 3504 // saved_mark_word() will return top() between pauses, i.e., 3505 // during concurrent refinement. So we don't need the 3506 // is_gc_active() check to decided which top to use when 3507 // scanning cards (see CR 7039627). 3508 increment_gc_time_stamp(); 3509 3510 if (VerifyRememberedSets) { 3511 log_info(gc, verify)("[Verifying RemSets after GC]"); 3512 VerifyRegionRemSetClosure v_cl; 3513 heap_region_iterate(&v_cl); 3514 } 3515 3516 _verifier->verify_after_gc(); 3517 _verifier->check_bitmaps("GC End"); 3518 3519 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 3520 ref_processor_stw()->verify_no_references_recorded(); 3521 3522 // CM reference discovery will be re-enabled if necessary. 3523 } 3524 3525 #ifdef TRACESPINNING 3526 ParallelTaskTerminator::print_termination_counts(); 3527 #endif 3528 3529 gc_epilogue(false); 3530 } 3531 3532 // Print the remainder of the GC log output. 3533 if (evacuation_failed()) { 3534 log_info(gc)("To-space exhausted"); 3535 } 3536 3537 g1_policy()->print_phases(); 3538 heap_transition.print(); 3539 3540 // It is not yet to safe to tell the concurrent mark to 3541 // start as we have some optional output below. We don't want the 3542 // output from the concurrent mark thread interfering with this 3543 // logging output either. 3544 3545 _hrm.verify_optional(); 3546 _verifier->verify_region_sets_optional(); 3547 3548 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3549 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3550 3551 print_heap_after_gc(); 3552 print_heap_regions(); 3553 trace_heap_after_gc(_gc_tracer_stw); 3554 3555 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3556 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3557 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3558 // before any GC notifications are raised. 3559 g1mm()->update_sizes(); 3560 3561 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3562 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 3563 _gc_timer_stw->register_gc_end(); 3564 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3565 } 3566 // It should now be safe to tell the concurrent mark thread to start 3567 // without its logging output interfering with the logging output 3568 // that came from the pause. 3569 3570 if (should_start_conc_mark) { 3571 // CAUTION: after the doConcurrentMark() call below, 3572 // the concurrent marking thread(s) could be running 3573 // concurrently with us. Make sure that anything after 3574 // this point does not assume that we are the only GC thread 3575 // running. Note: of course, the actual marking work will 3576 // not start until the safepoint itself is released in 3577 // SuspendibleThreadSet::desynchronize(). 3578 doConcurrentMark(); 3579 } 3580 3581 return true; 3582 } 3583 3584 void G1CollectedHeap::restore_preserved_marks() { 3585 G1RestorePreservedMarksTask rpm_task(_preserved_objs); 3586 workers()->run_task(&rpm_task); 3587 } 3588 3589 void G1CollectedHeap::remove_self_forwarding_pointers() { 3590 G1ParRemoveSelfForwardPtrsTask rsfp_task; 3591 workers()->run_task(&rsfp_task); 3592 } 3593 3594 void G1CollectedHeap::restore_after_evac_failure() { 3595 double remove_self_forwards_start = os::elapsedTime(); 3596 3597 remove_self_forwarding_pointers(); 3598 restore_preserved_marks(); 3599 3600 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3601 } 3602 3603 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 3604 if (!_evacuation_failed) { 3605 _evacuation_failed = true; 3606 } 3607 3608 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3609 3610 // We want to call the "for_promotion_failure" version only in the 3611 // case of a promotion failure. 3612 if (m->must_be_preserved_for_promotion_failure(obj)) { 3613 OopAndMarkOop elem(obj, m); 3614 _preserved_objs[worker_id].push(elem); 3615 } 3616 } 3617 3618 bool G1ParEvacuateFollowersClosure::offer_termination() { 3619 G1ParScanThreadState* const pss = par_scan_state(); 3620 start_term_time(); 3621 const bool res = terminator()->offer_termination(); 3622 end_term_time(); 3623 return res; 3624 } 3625 3626 void G1ParEvacuateFollowersClosure::do_void() { 3627 G1ParScanThreadState* const pss = par_scan_state(); 3628 pss->trim_queue(); 3629 do { 3630 pss->steal_and_trim_queue(queues()); 3631 } while (!offer_termination()); 3632 } 3633 3634 class G1ParTask : public AbstractGangTask { 3635 protected: 3636 G1CollectedHeap* _g1h; 3637 G1ParScanThreadStateSet* _pss; 3638 RefToScanQueueSet* _queues; 3639 G1RootProcessor* _root_processor; 3640 ParallelTaskTerminator _terminator; 3641 uint _n_workers; 3642 3643 public: 3644 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 3645 : AbstractGangTask("G1 collection"), 3646 _g1h(g1h), 3647 _pss(per_thread_states), 3648 _queues(task_queues), 3649 _root_processor(root_processor), 3650 _terminator(n_workers, _queues), 3651 _n_workers(n_workers) 3652 {} 3653 3654 void work(uint worker_id) { 3655 if (worker_id >= _n_workers) return; // no work needed this round 3656 3657 double start_sec = os::elapsedTime(); 3658 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 3659 3660 { 3661 ResourceMark rm; 3662 HandleMark hm; 3663 3664 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 3665 3666 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3667 pss->set_ref_processor(rp); 3668 3669 double start_strong_roots_sec = os::elapsedTime(); 3670 3671 _root_processor->evacuate_roots(pss->closures(), worker_id); 3672 3673 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss); 3674 3675 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid 3676 // treating the nmethods visited to act as roots for concurrent marking. 3677 // We only want to make sure that the oops in the nmethods are adjusted with regard to the 3678 // objects copied by the current evacuation. 3679 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl, 3680 pss->closures()->weak_codeblobs(), 3681 worker_id); 3682 3683 _pss->add_cards_scanned(worker_id, cards_scanned); 3684 3685 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 3686 3687 double term_sec = 0.0; 3688 size_t evac_term_attempts = 0; 3689 { 3690 double start = os::elapsedTime(); 3691 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator); 3692 evac.do_void(); 3693 3694 evac_term_attempts = evac.term_attempts(); 3695 term_sec = evac.term_time(); 3696 double elapsed_sec = os::elapsedTime() - start; 3697 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 3698 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 3699 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 3700 } 3701 3702 assert(pss->queue_is_empty(), "should be empty"); 3703 3704 if (log_is_enabled(Debug, gc, task, stats)) { 3705 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3706 size_t lab_waste; 3707 size_t lab_undo_waste; 3708 pss->waste(lab_waste, lab_undo_waste); 3709 _g1h->print_termination_stats(worker_id, 3710 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 3711 strong_roots_sec * 1000.0, /* strong roots time */ 3712 term_sec * 1000.0, /* evac term time */ 3713 evac_term_attempts, /* evac term attempts */ 3714 lab_waste, /* alloc buffer waste */ 3715 lab_undo_waste /* undo waste */ 3716 ); 3717 } 3718 3719 // Close the inner scope so that the ResourceMark and HandleMark 3720 // destructors are executed here and are included as part of the 3721 // "GC Worker Time". 3722 } 3723 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 3724 } 3725 }; 3726 3727 void G1CollectedHeap::print_termination_stats_hdr() { 3728 log_debug(gc, task, stats)("GC Termination Stats"); 3729 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 3730 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo"); 3731 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 3732 } 3733 3734 void G1CollectedHeap::print_termination_stats(uint worker_id, 3735 double elapsed_ms, 3736 double strong_roots_ms, 3737 double term_ms, 3738 size_t term_attempts, 3739 size_t alloc_buffer_waste, 3740 size_t undo_waste) const { 3741 log_debug(gc, task, stats) 3742 ("%3d %9.2f %9.2f %6.2f " 3743 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 3744 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 3745 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 3746 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 3747 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 3748 alloc_buffer_waste * HeapWordSize / K, 3749 undo_waste * HeapWordSize / K); 3750 } 3751 3752 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 3753 private: 3754 BoolObjectClosure* _is_alive; 3755 int _initial_string_table_size; 3756 int _initial_symbol_table_size; 3757 3758 bool _process_strings; 3759 int _strings_processed; 3760 int _strings_removed; 3761 3762 bool _process_symbols; 3763 int _symbols_processed; 3764 int _symbols_removed; 3765 3766 public: 3767 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 3768 AbstractGangTask("String/Symbol Unlinking"), 3769 _is_alive(is_alive), 3770 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 3771 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 3772 3773 _initial_string_table_size = StringTable::the_table()->table_size(); 3774 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 3775 if (process_strings) { 3776 StringTable::clear_parallel_claimed_index(); 3777 } 3778 if (process_symbols) { 3779 SymbolTable::clear_parallel_claimed_index(); 3780 } 3781 } 3782 3783 ~G1StringSymbolTableUnlinkTask() { 3784 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 3785 "claim value %d after unlink less than initial string table size %d", 3786 StringTable::parallel_claimed_index(), _initial_string_table_size); 3787 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 3788 "claim value %d after unlink less than initial symbol table size %d", 3789 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size); 3790 3791 log_debug(gc, stringdedup)("Cleaned string and symbol table, " 3792 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, " 3793 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed", 3794 strings_processed(), strings_removed(), 3795 symbols_processed(), symbols_removed()); 3796 } 3797 3798 void work(uint worker_id) { 3799 int strings_processed = 0; 3800 int strings_removed = 0; 3801 int symbols_processed = 0; 3802 int symbols_removed = 0; 3803 if (_process_strings) { 3804 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 3805 Atomic::add(strings_processed, &_strings_processed); 3806 Atomic::add(strings_removed, &_strings_removed); 3807 } 3808 if (_process_symbols) { 3809 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 3810 Atomic::add(symbols_processed, &_symbols_processed); 3811 Atomic::add(symbols_removed, &_symbols_removed); 3812 } 3813 } 3814 3815 size_t strings_processed() const { return (size_t)_strings_processed; } 3816 size_t strings_removed() const { return (size_t)_strings_removed; } 3817 3818 size_t symbols_processed() const { return (size_t)_symbols_processed; } 3819 size_t symbols_removed() const { return (size_t)_symbols_removed; } 3820 }; 3821 3822 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 3823 private: 3824 static Monitor* _lock; 3825 3826 BoolObjectClosure* const _is_alive; 3827 const bool _unloading_occurred; 3828 const uint _num_workers; 3829 3830 // Variables used to claim nmethods. 3831 nmethod* _first_nmethod; 3832 volatile nmethod* _claimed_nmethod; 3833 3834 // The list of nmethods that need to be processed by the second pass. 3835 volatile nmethod* _postponed_list; 3836 volatile uint _num_entered_barrier; 3837 3838 public: 3839 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 3840 _is_alive(is_alive), 3841 _unloading_occurred(unloading_occurred), 3842 _num_workers(num_workers), 3843 _first_nmethod(NULL), 3844 _claimed_nmethod(NULL), 3845 _postponed_list(NULL), 3846 _num_entered_barrier(0) 3847 { 3848 nmethod::increase_unloading_clock(); 3849 // Get first alive nmethod 3850 NMethodIterator iter = NMethodIterator(); 3851 if(iter.next_alive()) { 3852 _first_nmethod = iter.method(); 3853 } 3854 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 3855 } 3856 3857 ~G1CodeCacheUnloadingTask() { 3858 CodeCache::verify_clean_inline_caches(); 3859 3860 CodeCache::set_needs_cache_clean(false); 3861 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 3862 3863 CodeCache::verify_icholder_relocations(); 3864 } 3865 3866 private: 3867 void add_to_postponed_list(nmethod* nm) { 3868 nmethod* old; 3869 do { 3870 old = (nmethod*)_postponed_list; 3871 nm->set_unloading_next(old); 3872 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 3873 } 3874 3875 void clean_nmethod(nmethod* nm) { 3876 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 3877 3878 if (postponed) { 3879 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 3880 add_to_postponed_list(nm); 3881 } 3882 3883 // Mark that this thread has been cleaned/unloaded. 3884 // After this call, it will be safe to ask if this nmethod was unloaded or not. 3885 nm->set_unloading_clock(nmethod::global_unloading_clock()); 3886 } 3887 3888 void clean_nmethod_postponed(nmethod* nm) { 3889 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 3890 } 3891 3892 static const int MaxClaimNmethods = 16; 3893 3894 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 3895 nmethod* first; 3896 NMethodIterator last; 3897 3898 do { 3899 *num_claimed_nmethods = 0; 3900 3901 first = (nmethod*)_claimed_nmethod; 3902 last = NMethodIterator(first); 3903 3904 if (first != NULL) { 3905 3906 for (int i = 0; i < MaxClaimNmethods; i++) { 3907 if (!last.next_alive()) { 3908 break; 3909 } 3910 claimed_nmethods[i] = last.method(); 3911 (*num_claimed_nmethods)++; 3912 } 3913 } 3914 3915 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 3916 } 3917 3918 nmethod* claim_postponed_nmethod() { 3919 nmethod* claim; 3920 nmethod* next; 3921 3922 do { 3923 claim = (nmethod*)_postponed_list; 3924 if (claim == NULL) { 3925 return NULL; 3926 } 3927 3928 next = claim->unloading_next(); 3929 3930 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 3931 3932 return claim; 3933 } 3934 3935 public: 3936 // Mark that we're done with the first pass of nmethod cleaning. 3937 void barrier_mark(uint worker_id) { 3938 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3939 _num_entered_barrier++; 3940 if (_num_entered_barrier == _num_workers) { 3941 ml.notify_all(); 3942 } 3943 } 3944 3945 // See if we have to wait for the other workers to 3946 // finish their first-pass nmethod cleaning work. 3947 void barrier_wait(uint worker_id) { 3948 if (_num_entered_barrier < _num_workers) { 3949 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3950 while (_num_entered_barrier < _num_workers) { 3951 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 3952 } 3953 } 3954 } 3955 3956 // Cleaning and unloading of nmethods. Some work has to be postponed 3957 // to the second pass, when we know which nmethods survive. 3958 void work_first_pass(uint worker_id) { 3959 // The first nmethods is claimed by the first worker. 3960 if (worker_id == 0 && _first_nmethod != NULL) { 3961 clean_nmethod(_first_nmethod); 3962 _first_nmethod = NULL; 3963 } 3964 3965 int num_claimed_nmethods; 3966 nmethod* claimed_nmethods[MaxClaimNmethods]; 3967 3968 while (true) { 3969 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 3970 3971 if (num_claimed_nmethods == 0) { 3972 break; 3973 } 3974 3975 for (int i = 0; i < num_claimed_nmethods; i++) { 3976 clean_nmethod(claimed_nmethods[i]); 3977 } 3978 } 3979 } 3980 3981 void work_second_pass(uint worker_id) { 3982 nmethod* nm; 3983 // Take care of postponed nmethods. 3984 while ((nm = claim_postponed_nmethod()) != NULL) { 3985 clean_nmethod_postponed(nm); 3986 } 3987 } 3988 }; 3989 3990 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 3991 3992 class G1KlassCleaningTask : public StackObj { 3993 BoolObjectClosure* _is_alive; 3994 volatile jint _clean_klass_tree_claimed; 3995 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 3996 3997 public: 3998 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 3999 _is_alive(is_alive), 4000 _clean_klass_tree_claimed(0), 4001 _klass_iterator() { 4002 } 4003 4004 private: 4005 bool claim_clean_klass_tree_task() { 4006 if (_clean_klass_tree_claimed) { 4007 return false; 4008 } 4009 4010 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 4011 } 4012 4013 InstanceKlass* claim_next_klass() { 4014 Klass* klass; 4015 do { 4016 klass =_klass_iterator.next_klass(); 4017 } while (klass != NULL && !klass->is_instance_klass()); 4018 4019 // this can be null so don't call InstanceKlass::cast 4020 return static_cast<InstanceKlass*>(klass); 4021 } 4022 4023 public: 4024 4025 void clean_klass(InstanceKlass* ik) { 4026 ik->clean_weak_instanceklass_links(_is_alive); 4027 } 4028 4029 void work() { 4030 ResourceMark rm; 4031 4032 // One worker will clean the subklass/sibling klass tree. 4033 if (claim_clean_klass_tree_task()) { 4034 Klass::clean_subklass_tree(_is_alive); 4035 } 4036 4037 // All workers will help cleaning the classes, 4038 InstanceKlass* klass; 4039 while ((klass = claim_next_klass()) != NULL) { 4040 clean_klass(klass); 4041 } 4042 } 4043 }; 4044 4045 // To minimize the remark pause times, the tasks below are done in parallel. 4046 class G1ParallelCleaningTask : public AbstractGangTask { 4047 private: 4048 G1StringSymbolTableUnlinkTask _string_symbol_task; 4049 G1CodeCacheUnloadingTask _code_cache_task; 4050 G1KlassCleaningTask _klass_cleaning_task; 4051 4052 public: 4053 // The constructor is run in the VMThread. 4054 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 4055 AbstractGangTask("Parallel Cleaning"), 4056 _string_symbol_task(is_alive, process_strings, process_symbols), 4057 _code_cache_task(num_workers, is_alive, unloading_occurred), 4058 _klass_cleaning_task(is_alive) { 4059 } 4060 4061 // The parallel work done by all worker threads. 4062 void work(uint worker_id) { 4063 // Do first pass of code cache cleaning. 4064 _code_cache_task.work_first_pass(worker_id); 4065 4066 // Let the threads mark that the first pass is done. 4067 _code_cache_task.barrier_mark(worker_id); 4068 4069 // Clean the Strings and Symbols. 4070 _string_symbol_task.work(worker_id); 4071 4072 // Wait for all workers to finish the first code cache cleaning pass. 4073 _code_cache_task.barrier_wait(worker_id); 4074 4075 // Do the second code cache cleaning work, which realize on 4076 // the liveness information gathered during the first pass. 4077 _code_cache_task.work_second_pass(worker_id); 4078 4079 // Clean all klasses that were not unloaded. 4080 _klass_cleaning_task.work(); 4081 } 4082 }; 4083 4084 4085 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 4086 bool process_strings, 4087 bool process_symbols, 4088 bool class_unloading_occurred) { 4089 uint n_workers = workers()->active_workers(); 4090 4091 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 4092 n_workers, class_unloading_occurred); 4093 workers()->run_task(&g1_unlink_task); 4094 } 4095 4096 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 4097 bool process_strings, bool process_symbols) { 4098 { 4099 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 4100 workers()->run_task(&g1_unlink_task); 4101 } 4102 4103 if (G1StringDedup::is_enabled()) { 4104 G1StringDedup::unlink(is_alive); 4105 } 4106 } 4107 4108 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 4109 private: 4110 DirtyCardQueueSet* _queue; 4111 G1CollectedHeap* _g1h; 4112 public: 4113 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 4114 _queue(queue), _g1h(g1h) { } 4115 4116 virtual void work(uint worker_id) { 4117 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 4118 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 4119 4120 RedirtyLoggedCardTableEntryClosure cl(_g1h); 4121 _queue->par_apply_closure_to_all_completed_buffers(&cl); 4122 4123 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 4124 } 4125 }; 4126 4127 void G1CollectedHeap::redirty_logged_cards() { 4128 double redirty_logged_cards_start = os::elapsedTime(); 4129 4130 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 4131 dirty_card_queue_set().reset_for_par_iteration(); 4132 workers()->run_task(&redirty_task); 4133 4134 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 4135 dcq.merge_bufferlists(&dirty_card_queue_set()); 4136 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 4137 4138 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 4139 } 4140 4141 // Weak Reference Processing support 4142 4143 // An always "is_alive" closure that is used to preserve referents. 4144 // If the object is non-null then it's alive. Used in the preservation 4145 // of referent objects that are pointed to by reference objects 4146 // discovered by the CM ref processor. 4147 class G1AlwaysAliveClosure: public BoolObjectClosure { 4148 G1CollectedHeap* _g1; 4149 public: 4150 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4151 bool do_object_b(oop p) { 4152 if (p != NULL) { 4153 return true; 4154 } 4155 return false; 4156 } 4157 }; 4158 4159 bool G1STWIsAliveClosure::do_object_b(oop p) { 4160 // An object is reachable if it is outside the collection set, 4161 // or is inside and copied. 4162 return !_g1->is_in_cset(p) || p->is_forwarded(); 4163 } 4164 4165 // Non Copying Keep Alive closure 4166 class G1KeepAliveClosure: public OopClosure { 4167 G1CollectedHeap* _g1; 4168 public: 4169 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4170 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 4171 void do_oop(oop* p) { 4172 oop obj = *p; 4173 assert(obj != NULL, "the caller should have filtered out NULL values"); 4174 4175 const InCSetState cset_state = _g1->in_cset_state(obj); 4176 if (!cset_state.is_in_cset_or_humongous()) { 4177 return; 4178 } 4179 if (cset_state.is_in_cset()) { 4180 assert( obj->is_forwarded(), "invariant" ); 4181 *p = obj->forwardee(); 4182 } else { 4183 assert(!obj->is_forwarded(), "invariant" ); 4184 assert(cset_state.is_humongous(), 4185 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 4186 _g1->set_humongous_is_live(obj); 4187 } 4188 } 4189 }; 4190 4191 // Copying Keep Alive closure - can be called from both 4192 // serial and parallel code as long as different worker 4193 // threads utilize different G1ParScanThreadState instances 4194 // and different queues. 4195 4196 class G1CopyingKeepAliveClosure: public OopClosure { 4197 G1CollectedHeap* _g1h; 4198 OopClosure* _copy_non_heap_obj_cl; 4199 G1ParScanThreadState* _par_scan_state; 4200 4201 public: 4202 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 4203 OopClosure* non_heap_obj_cl, 4204 G1ParScanThreadState* pss): 4205 _g1h(g1h), 4206 _copy_non_heap_obj_cl(non_heap_obj_cl), 4207 _par_scan_state(pss) 4208 {} 4209 4210 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 4211 virtual void do_oop( oop* p) { do_oop_work(p); } 4212 4213 template <class T> void do_oop_work(T* p) { 4214 oop obj = oopDesc::load_decode_heap_oop(p); 4215 4216 if (_g1h->is_in_cset_or_humongous(obj)) { 4217 // If the referent object has been forwarded (either copied 4218 // to a new location or to itself in the event of an 4219 // evacuation failure) then we need to update the reference 4220 // field and, if both reference and referent are in the G1 4221 // heap, update the RSet for the referent. 4222 // 4223 // If the referent has not been forwarded then we have to keep 4224 // it alive by policy. Therefore we have copy the referent. 4225 // 4226 // If the reference field is in the G1 heap then we can push 4227 // on the PSS queue. When the queue is drained (after each 4228 // phase of reference processing) the object and it's followers 4229 // will be copied, the reference field set to point to the 4230 // new location, and the RSet updated. Otherwise we need to 4231 // use the the non-heap or metadata closures directly to copy 4232 // the referent object and update the pointer, while avoiding 4233 // updating the RSet. 4234 4235 if (_g1h->is_in_g1_reserved(p)) { 4236 _par_scan_state->push_on_queue(p); 4237 } else { 4238 assert(!Metaspace::contains((const void*)p), 4239 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)); 4240 _copy_non_heap_obj_cl->do_oop(p); 4241 } 4242 } 4243 } 4244 }; 4245 4246 // Serial drain queue closure. Called as the 'complete_gc' 4247 // closure for each discovered list in some of the 4248 // reference processing phases. 4249 4250 class G1STWDrainQueueClosure: public VoidClosure { 4251 protected: 4252 G1CollectedHeap* _g1h; 4253 G1ParScanThreadState* _par_scan_state; 4254 4255 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4256 4257 public: 4258 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 4259 _g1h(g1h), 4260 _par_scan_state(pss) 4261 { } 4262 4263 void do_void() { 4264 G1ParScanThreadState* const pss = par_scan_state(); 4265 pss->trim_queue(); 4266 } 4267 }; 4268 4269 // Parallel Reference Processing closures 4270 4271 // Implementation of AbstractRefProcTaskExecutor for parallel reference 4272 // processing during G1 evacuation pauses. 4273 4274 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 4275 private: 4276 G1CollectedHeap* _g1h; 4277 G1ParScanThreadStateSet* _pss; 4278 RefToScanQueueSet* _queues; 4279 WorkGang* _workers; 4280 uint _active_workers; 4281 4282 public: 4283 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 4284 G1ParScanThreadStateSet* per_thread_states, 4285 WorkGang* workers, 4286 RefToScanQueueSet *task_queues, 4287 uint n_workers) : 4288 _g1h(g1h), 4289 _pss(per_thread_states), 4290 _queues(task_queues), 4291 _workers(workers), 4292 _active_workers(n_workers) 4293 { 4294 g1h->ref_processor_stw()->set_active_mt_degree(n_workers); 4295 } 4296 4297 // Executes the given task using concurrent marking worker threads. 4298 virtual void execute(ProcessTask& task); 4299 virtual void execute(EnqueueTask& task); 4300 }; 4301 4302 // Gang task for possibly parallel reference processing 4303 4304 class G1STWRefProcTaskProxy: public AbstractGangTask { 4305 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 4306 ProcessTask& _proc_task; 4307 G1CollectedHeap* _g1h; 4308 G1ParScanThreadStateSet* _pss; 4309 RefToScanQueueSet* _task_queues; 4310 ParallelTaskTerminator* _terminator; 4311 4312 public: 4313 G1STWRefProcTaskProxy(ProcessTask& proc_task, 4314 G1CollectedHeap* g1h, 4315 G1ParScanThreadStateSet* per_thread_states, 4316 RefToScanQueueSet *task_queues, 4317 ParallelTaskTerminator* terminator) : 4318 AbstractGangTask("Process reference objects in parallel"), 4319 _proc_task(proc_task), 4320 _g1h(g1h), 4321 _pss(per_thread_states), 4322 _task_queues(task_queues), 4323 _terminator(terminator) 4324 {} 4325 4326 virtual void work(uint worker_id) { 4327 // The reference processing task executed by a single worker. 4328 ResourceMark rm; 4329 HandleMark hm; 4330 4331 G1STWIsAliveClosure is_alive(_g1h); 4332 4333 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4334 pss->set_ref_processor(NULL); 4335 4336 // Keep alive closure. 4337 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 4338 4339 // Complete GC closure 4340 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator); 4341 4342 // Call the reference processing task's work routine. 4343 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 4344 4345 // Note we cannot assert that the refs array is empty here as not all 4346 // of the processing tasks (specifically phase2 - pp2_work) execute 4347 // the complete_gc closure (which ordinarily would drain the queue) so 4348 // the queue may not be empty. 4349 } 4350 }; 4351 4352 // Driver routine for parallel reference processing. 4353 // Creates an instance of the ref processing gang 4354 // task and has the worker threads execute it. 4355 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 4356 assert(_workers != NULL, "Need parallel worker threads."); 4357 4358 ParallelTaskTerminator terminator(_active_workers, _queues); 4359 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 4360 4361 _workers->run_task(&proc_task_proxy); 4362 } 4363 4364 // Gang task for parallel reference enqueueing. 4365 4366 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 4367 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 4368 EnqueueTask& _enq_task; 4369 4370 public: 4371 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 4372 AbstractGangTask("Enqueue reference objects in parallel"), 4373 _enq_task(enq_task) 4374 { } 4375 4376 virtual void work(uint worker_id) { 4377 _enq_task.work(worker_id); 4378 } 4379 }; 4380 4381 // Driver routine for parallel reference enqueueing. 4382 // Creates an instance of the ref enqueueing gang 4383 // task and has the worker threads execute it. 4384 4385 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 4386 assert(_workers != NULL, "Need parallel worker threads."); 4387 4388 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 4389 4390 _workers->run_task(&enq_task_proxy); 4391 } 4392 4393 // End of weak reference support closures 4394 4395 // Abstract task used to preserve (i.e. copy) any referent objects 4396 // that are in the collection set and are pointed to by reference 4397 // objects discovered by the CM ref processor. 4398 4399 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 4400 protected: 4401 G1CollectedHeap* _g1h; 4402 G1ParScanThreadStateSet* _pss; 4403 RefToScanQueueSet* _queues; 4404 ParallelTaskTerminator _terminator; 4405 uint _n_workers; 4406 4407 public: 4408 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) : 4409 AbstractGangTask("ParPreserveCMReferents"), 4410 _g1h(g1h), 4411 _pss(per_thread_states), 4412 _queues(task_queues), 4413 _terminator(workers, _queues), 4414 _n_workers(workers) 4415 { 4416 g1h->ref_processor_cm()->set_active_mt_degree(workers); 4417 } 4418 4419 void work(uint worker_id) { 4420 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id); 4421 4422 ResourceMark rm; 4423 HandleMark hm; 4424 4425 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4426 pss->set_ref_processor(NULL); 4427 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 4428 4429 // Is alive closure 4430 G1AlwaysAliveClosure always_alive(_g1h); 4431 4432 // Copying keep alive closure. Applied to referent objects that need 4433 // to be copied. 4434 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 4435 4436 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 4437 4438 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 4439 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 4440 4441 // limit is set using max_num_q() - which was set using ParallelGCThreads. 4442 // So this must be true - but assert just in case someone decides to 4443 // change the worker ids. 4444 assert(worker_id < limit, "sanity"); 4445 assert(!rp->discovery_is_atomic(), "check this code"); 4446 4447 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 4448 for (uint idx = worker_id; idx < limit; idx += stride) { 4449 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 4450 4451 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 4452 while (iter.has_next()) { 4453 // Since discovery is not atomic for the CM ref processor, we 4454 // can see some null referent objects. 4455 iter.load_ptrs(DEBUG_ONLY(true)); 4456 oop ref = iter.obj(); 4457 4458 // This will filter nulls. 4459 if (iter.is_referent_alive()) { 4460 iter.make_referent_alive(); 4461 } 4462 iter.move_to_next(); 4463 } 4464 } 4465 4466 // Drain the queue - which may cause stealing 4467 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator); 4468 drain_queue.do_void(); 4469 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 4470 assert(pss->queue_is_empty(), "should be"); 4471 } 4472 }; 4473 4474 void G1CollectedHeap::process_weak_jni_handles() { 4475 double ref_proc_start = os::elapsedTime(); 4476 4477 G1STWIsAliveClosure is_alive(this); 4478 G1KeepAliveClosure keep_alive(this); 4479 JNIHandles::weak_oops_do(&is_alive, &keep_alive); 4480 4481 double ref_proc_time = os::elapsedTime() - ref_proc_start; 4482 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 4483 } 4484 4485 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) { 4486 double preserve_cm_referents_start = os::elapsedTime(); 4487 // Any reference objects, in the collection set, that were 'discovered' 4488 // by the CM ref processor should have already been copied (either by 4489 // applying the external root copy closure to the discovered lists, or 4490 // by following an RSet entry). 4491 // 4492 // But some of the referents, that are in the collection set, that these 4493 // reference objects point to may not have been copied: the STW ref 4494 // processor would have seen that the reference object had already 4495 // been 'discovered' and would have skipped discovering the reference, 4496 // but would not have treated the reference object as a regular oop. 4497 // As a result the copy closure would not have been applied to the 4498 // referent object. 4499 // 4500 // We need to explicitly copy these referent objects - the references 4501 // will be processed at the end of remarking. 4502 // 4503 // We also need to do this copying before we process the reference 4504 // objects discovered by the STW ref processor in case one of these 4505 // referents points to another object which is also referenced by an 4506 // object discovered by the STW ref processor. 4507 4508 uint no_of_gc_workers = workers()->active_workers(); 4509 4510 G1ParPreserveCMReferentsTask keep_cm_referents(this, 4511 per_thread_states, 4512 no_of_gc_workers, 4513 _task_queues); 4514 workers()->run_task(&keep_cm_referents); 4515 4516 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms((os::elapsedTime() - preserve_cm_referents_start) * 1000.0); 4517 } 4518 4519 // Weak Reference processing during an evacuation pause (part 1). 4520 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 4521 double ref_proc_start = os::elapsedTime(); 4522 4523 ReferenceProcessor* rp = _ref_processor_stw; 4524 assert(rp->discovery_enabled(), "should have been enabled"); 4525 4526 // Closure to test whether a referent is alive. 4527 G1STWIsAliveClosure is_alive(this); 4528 4529 // Even when parallel reference processing is enabled, the processing 4530 // of JNI refs is serial and performed serially by the current thread 4531 // rather than by a worker. The following PSS will be used for processing 4532 // JNI refs. 4533 4534 // Use only a single queue for this PSS. 4535 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 4536 pss->set_ref_processor(NULL); 4537 assert(pss->queue_is_empty(), "pre-condition"); 4538 4539 // Keep alive closure. 4540 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss); 4541 4542 // Serial Complete GC closure 4543 G1STWDrainQueueClosure drain_queue(this, pss); 4544 4545 // Setup the soft refs policy... 4546 rp->setup_policy(false); 4547 4548 ReferenceProcessorStats stats; 4549 if (!rp->processing_is_mt()) { 4550 // Serial reference processing... 4551 stats = rp->process_discovered_references(&is_alive, 4552 &keep_alive, 4553 &drain_queue, 4554 NULL, 4555 _gc_timer_stw); 4556 } else { 4557 uint no_of_gc_workers = workers()->active_workers(); 4558 4559 // Parallel reference processing 4560 assert(no_of_gc_workers <= rp->max_num_q(), 4561 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 4562 no_of_gc_workers, rp->max_num_q()); 4563 4564 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers); 4565 stats = rp->process_discovered_references(&is_alive, 4566 &keep_alive, 4567 &drain_queue, 4568 &par_task_executor, 4569 _gc_timer_stw); 4570 } 4571 4572 _gc_tracer_stw->report_gc_reference_stats(stats); 4573 4574 // We have completed copying any necessary live referent objects. 4575 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 4576 4577 double ref_proc_time = os::elapsedTime() - ref_proc_start; 4578 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 4579 } 4580 4581 // Weak Reference processing during an evacuation pause (part 2). 4582 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 4583 double ref_enq_start = os::elapsedTime(); 4584 4585 ReferenceProcessor* rp = _ref_processor_stw; 4586 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 4587 4588 // Now enqueue any remaining on the discovered lists on to 4589 // the pending list. 4590 if (!rp->processing_is_mt()) { 4591 // Serial reference processing... 4592 rp->enqueue_discovered_references(); 4593 } else { 4594 // Parallel reference enqueueing 4595 4596 uint n_workers = workers()->active_workers(); 4597 4598 assert(n_workers <= rp->max_num_q(), 4599 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 4600 n_workers, rp->max_num_q()); 4601 4602 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers); 4603 rp->enqueue_discovered_references(&par_task_executor); 4604 } 4605 4606 rp->verify_no_references_recorded(); 4607 assert(!rp->discovery_enabled(), "should have been disabled"); 4608 4609 // FIXME 4610 // CM's reference processing also cleans up the string and symbol tables. 4611 // Should we do that here also? We could, but it is a serial operation 4612 // and could significantly increase the pause time. 4613 4614 double ref_enq_time = os::elapsedTime() - ref_enq_start; 4615 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 4616 } 4617 4618 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 4619 double merge_pss_time_start = os::elapsedTime(); 4620 per_thread_states->flush(); 4621 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 4622 } 4623 4624 void G1CollectedHeap::pre_evacuate_collection_set() { 4625 _expand_heap_after_alloc_failure = true; 4626 _evacuation_failed = false; 4627 4628 // Disable the hot card cache. 4629 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 4630 hot_card_cache->reset_hot_cache_claimed_index(); 4631 hot_card_cache->set_use_cache(false); 4632 4633 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 4634 } 4635 4636 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 4637 // Should G1EvacuationFailureALot be in effect for this GC? 4638 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 4639 4640 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 4641 double start_par_time_sec = os::elapsedTime(); 4642 double end_par_time_sec; 4643 4644 { 4645 const uint n_workers = workers()->active_workers(); 4646 G1RootProcessor root_processor(this, n_workers); 4647 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 4648 // InitialMark needs claim bits to keep track of the marked-through CLDs. 4649 if (collector_state()->during_initial_mark_pause()) { 4650 ClassLoaderDataGraph::clear_claimed_marks(); 4651 } 4652 4653 print_termination_stats_hdr(); 4654 4655 workers()->run_task(&g1_par_task); 4656 end_par_time_sec = os::elapsedTime(); 4657 4658 // Closing the inner scope will execute the destructor 4659 // for the G1RootProcessor object. We record the current 4660 // elapsed time before closing the scope so that time 4661 // taken for the destructor is NOT included in the 4662 // reported parallel time. 4663 } 4664 4665 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 4666 4667 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 4668 phase_times->record_par_time(par_time_ms); 4669 4670 double code_root_fixup_time_ms = 4671 (os::elapsedTime() - end_par_time_sec) * 1000.0; 4672 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 4673 } 4674 4675 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 4676 // Process any discovered reference objects - we have 4677 // to do this _before_ we retire the GC alloc regions 4678 // as we may have to copy some 'reachable' referent 4679 // objects (and their reachable sub-graphs) that were 4680 // not copied during the pause. 4681 if (g1_policy()->should_process_references()) { 4682 preserve_cm_referents(per_thread_states); 4683 process_discovered_references(per_thread_states); 4684 } else { 4685 ref_processor_stw()->verify_no_references_recorded(); 4686 process_weak_jni_handles(); 4687 } 4688 4689 if (G1StringDedup::is_enabled()) { 4690 double fixup_start = os::elapsedTime(); 4691 4692 G1STWIsAliveClosure is_alive(this); 4693 G1KeepAliveClosure keep_alive(this); 4694 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times()); 4695 4696 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 4697 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms); 4698 } 4699 4700 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 4701 4702 if (evacuation_failed()) { 4703 restore_after_evac_failure(); 4704 4705 // Reset the G1EvacuationFailureALot counters and flags 4706 // Note: the values are reset only when an actual 4707 // evacuation failure occurs. 4708 NOT_PRODUCT(reset_evacuation_should_fail();) 4709 } 4710 4711 // Enqueue any remaining references remaining on the STW 4712 // reference processor's discovered lists. We need to do 4713 // this after the card table is cleaned (and verified) as 4714 // the act of enqueueing entries on to the pending list 4715 // will log these updates (and dirty their associated 4716 // cards). We need these updates logged to update any 4717 // RSets. 4718 if (g1_policy()->should_process_references()) { 4719 enqueue_discovered_references(per_thread_states); 4720 } else { 4721 g1_policy()->phase_times()->record_ref_enq_time(0); 4722 } 4723 4724 _allocator->release_gc_alloc_regions(evacuation_info); 4725 4726 merge_per_thread_state_info(per_thread_states); 4727 4728 // Reset and re-enable the hot card cache. 4729 // Note the counts for the cards in the regions in the 4730 // collection set are reset when the collection set is freed. 4731 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 4732 hot_card_cache->reset_hot_cache(); 4733 hot_card_cache->set_use_cache(true); 4734 4735 purge_code_root_memory(); 4736 4737 redirty_logged_cards(); 4738 #if defined(COMPILER2) || INCLUDE_JVMCI 4739 DerivedPointerTable::update_pointers(); 4740 #endif 4741 } 4742 4743 void G1CollectedHeap::record_obj_copy_mem_stats() { 4744 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 4745 4746 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 4747 create_g1_evac_summary(&_old_evac_stats)); 4748 } 4749 4750 void G1CollectedHeap::free_region(HeapRegion* hr, 4751 FreeRegionList* free_list, 4752 bool par, 4753 bool locked) { 4754 assert(!hr->is_free(), "the region should not be free"); 4755 assert(!hr->is_empty(), "the region should not be empty"); 4756 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 4757 assert(free_list != NULL, "pre-condition"); 4758 4759 if (G1VerifyBitmaps) { 4760 MemRegion mr(hr->bottom(), hr->end()); 4761 concurrent_mark()->clearRangePrevBitmap(mr); 4762 } 4763 4764 // Clear the card counts for this region. 4765 // Note: we only need to do this if the region is not young 4766 // (since we don't refine cards in young regions). 4767 if (!hr->is_young()) { 4768 _cg1r->hot_card_cache()->reset_card_counts(hr); 4769 } 4770 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 4771 free_list->add_ordered(hr); 4772 } 4773 4774 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4775 FreeRegionList* free_list, 4776 bool par) { 4777 assert(hr->is_humongous(), "this is only for humongous regions"); 4778 assert(free_list != NULL, "pre-condition"); 4779 hr->clear_humongous(); 4780 free_region(hr, free_list, par); 4781 } 4782 4783 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 4784 const uint humongous_regions_removed) { 4785 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 4786 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4787 _old_set.bulk_remove(old_regions_removed); 4788 _humongous_set.bulk_remove(humongous_regions_removed); 4789 } 4790 4791 } 4792 4793 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4794 assert(list != NULL, "list can't be null"); 4795 if (!list->is_empty()) { 4796 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4797 _hrm.insert_list_into_free_list(list); 4798 } 4799 } 4800 4801 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4802 decrease_used(bytes); 4803 } 4804 4805 class G1ParCleanupCTTask : public AbstractGangTask { 4806 G1SATBCardTableModRefBS* _ct_bs; 4807 G1CollectedHeap* _g1h; 4808 HeapRegion* volatile _su_head; 4809 public: 4810 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 4811 G1CollectedHeap* g1h) : 4812 AbstractGangTask("G1 Par Cleanup CT Task"), 4813 _ct_bs(ct_bs), _g1h(g1h) { } 4814 4815 void work(uint worker_id) { 4816 HeapRegion* r; 4817 while (r = _g1h->pop_dirty_cards_region()) { 4818 clear_cards(r); 4819 } 4820 } 4821 4822 void clear_cards(HeapRegion* r) { 4823 // Cards of the survivors should have already been dirtied. 4824 if (!r->is_survivor()) { 4825 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 4826 } 4827 } 4828 }; 4829 4830 class G1ParScrubRemSetTask: public AbstractGangTask { 4831 protected: 4832 G1RemSet* _g1rs; 4833 BitMap* _region_bm; 4834 BitMap* _card_bm; 4835 HeapRegionClaimer _hrclaimer; 4836 4837 public: 4838 G1ParScrubRemSetTask(G1RemSet* g1_rs, BitMap* region_bm, BitMap* card_bm, uint num_workers) : 4839 AbstractGangTask("G1 ScrubRS"), 4840 _g1rs(g1_rs), 4841 _region_bm(region_bm), 4842 _card_bm(card_bm), 4843 _hrclaimer(num_workers) { 4844 } 4845 4846 void work(uint worker_id) { 4847 _g1rs->scrub(_region_bm, _card_bm, worker_id, &_hrclaimer); 4848 } 4849 }; 4850 4851 void G1CollectedHeap::scrub_rem_set(BitMap* region_bm, BitMap* card_bm) { 4852 uint num_workers = workers()->active_workers(); 4853 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), region_bm, card_bm, num_workers); 4854 workers()->run_task(&g1_par_scrub_rs_task); 4855 } 4856 4857 void G1CollectedHeap::cleanUpCardTable() { 4858 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 4859 double start = os::elapsedTime(); 4860 4861 { 4862 // Iterate over the dirty cards region list. 4863 G1ParCleanupCTTask cleanup_task(ct_bs, this); 4864 4865 workers()->run_task(&cleanup_task); 4866 #ifndef PRODUCT 4867 _verifier->verify_card_table_cleanup(); 4868 #endif 4869 } 4870 4871 double elapsed = os::elapsedTime() - start; 4872 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 4873 } 4874 4875 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4876 size_t pre_used = 0; 4877 FreeRegionList local_free_list("Local List for CSet Freeing"); 4878 4879 double young_time_ms = 0.0; 4880 double non_young_time_ms = 0.0; 4881 4882 // Since the collection set is a superset of the the young list, 4883 // all we need to do to clear the young list is clear its 4884 // head and length, and unlink any young regions in the code below 4885 _young_list->clear(); 4886 4887 G1CollectorPolicy* policy = g1_policy(); 4888 4889 double start_sec = os::elapsedTime(); 4890 bool non_young = true; 4891 4892 HeapRegion* cur = cs_head; 4893 int age_bound = -1; 4894 size_t rs_lengths = 0; 4895 4896 while (cur != NULL) { 4897 assert(!is_on_master_free_list(cur), "sanity"); 4898 if (non_young) { 4899 if (cur->is_young()) { 4900 double end_sec = os::elapsedTime(); 4901 double elapsed_ms = (end_sec - start_sec) * 1000.0; 4902 non_young_time_ms += elapsed_ms; 4903 4904 start_sec = os::elapsedTime(); 4905 non_young = false; 4906 } 4907 } else { 4908 if (!cur->is_young()) { 4909 double end_sec = os::elapsedTime(); 4910 double elapsed_ms = (end_sec - start_sec) * 1000.0; 4911 young_time_ms += elapsed_ms; 4912 4913 start_sec = os::elapsedTime(); 4914 non_young = true; 4915 } 4916 } 4917 4918 rs_lengths += cur->rem_set()->occupied_locked(); 4919 4920 HeapRegion* next = cur->next_in_collection_set(); 4921 assert(cur->in_collection_set(), "bad CS"); 4922 cur->set_next_in_collection_set(NULL); 4923 clear_in_cset(cur); 4924 4925 if (cur->is_young()) { 4926 int index = cur->young_index_in_cset(); 4927 assert(index != -1, "invariant"); 4928 assert((uint) index < collection_set()->young_region_length(), "invariant"); 4929 size_t words_survived = surviving_young_words[index]; 4930 cur->record_surv_words_in_group(words_survived); 4931 4932 // At this point the we have 'popped' cur from the collection set 4933 // (linked via next_in_collection_set()) but it is still in the 4934 // young list (linked via next_young_region()). Clear the 4935 // _next_young_region field. 4936 cur->set_next_young_region(NULL); 4937 } else { 4938 int index = cur->young_index_in_cset(); 4939 assert(index == -1, "invariant"); 4940 } 4941 4942 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 4943 (!cur->is_young() && cur->young_index_in_cset() == -1), 4944 "invariant" ); 4945 4946 if (!cur->evacuation_failed()) { 4947 MemRegion used_mr = cur->used_region(); 4948 4949 // And the region is empty. 4950 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 4951 pre_used += cur->used(); 4952 free_region(cur, &local_free_list, false /* par */, true /* locked */); 4953 } else { 4954 cur->uninstall_surv_rate_group(); 4955 if (cur->is_young()) { 4956 cur->set_young_index_in_cset(-1); 4957 } 4958 cur->set_evacuation_failed(false); 4959 // When moving a young gen region to old gen, we "allocate" that whole region 4960 // there. This is in addition to any already evacuated objects. Notify the 4961 // policy about that. 4962 // Old gen regions do not cause an additional allocation: both the objects 4963 // still in the region and the ones already moved are accounted for elsewhere. 4964 if (cur->is_young()) { 4965 policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes); 4966 } 4967 // The region is now considered to be old. 4968 cur->set_old(); 4969 // Do some allocation statistics accounting. Regions that failed evacuation 4970 // are always made old, so there is no need to update anything in the young 4971 // gen statistics, but we need to update old gen statistics. 4972 size_t used_words = cur->marked_bytes() / HeapWordSize; 4973 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words); 4974 _old_set.add(cur); 4975 evacuation_info.increment_collectionset_used_after(cur->used()); 4976 } 4977 cur = next; 4978 } 4979 4980 evacuation_info.set_regions_freed(local_free_list.length()); 4981 policy->record_max_rs_lengths(rs_lengths); 4982 policy->cset_regions_freed(); 4983 4984 double end_sec = os::elapsedTime(); 4985 double elapsed_ms = (end_sec - start_sec) * 1000.0; 4986 4987 if (non_young) { 4988 non_young_time_ms += elapsed_ms; 4989 } else { 4990 young_time_ms += elapsed_ms; 4991 } 4992 4993 prepend_to_freelist(&local_free_list); 4994 decrement_summary_bytes(pre_used); 4995 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 4996 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 4997 } 4998 4999 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 5000 private: 5001 FreeRegionList* _free_region_list; 5002 HeapRegionSet* _proxy_set; 5003 uint _humongous_regions_removed; 5004 size_t _freed_bytes; 5005 public: 5006 5007 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 5008 _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) { 5009 } 5010 5011 virtual bool doHeapRegion(HeapRegion* r) { 5012 if (!r->is_starts_humongous()) { 5013 return false; 5014 } 5015 5016 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 5017 5018 oop obj = (oop)r->bottom(); 5019 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 5020 5021 // The following checks whether the humongous object is live are sufficient. 5022 // The main additional check (in addition to having a reference from the roots 5023 // or the young gen) is whether the humongous object has a remembered set entry. 5024 // 5025 // A humongous object cannot be live if there is no remembered set for it 5026 // because: 5027 // - there can be no references from within humongous starts regions referencing 5028 // the object because we never allocate other objects into them. 5029 // (I.e. there are no intra-region references that may be missed by the 5030 // remembered set) 5031 // - as soon there is a remembered set entry to the humongous starts region 5032 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 5033 // until the end of a concurrent mark. 5034 // 5035 // It is not required to check whether the object has been found dead by marking 5036 // or not, in fact it would prevent reclamation within a concurrent cycle, as 5037 // all objects allocated during that time are considered live. 5038 // SATB marking is even more conservative than the remembered set. 5039 // So if at this point in the collection there is no remembered set entry, 5040 // nobody has a reference to it. 5041 // At the start of collection we flush all refinement logs, and remembered sets 5042 // are completely up-to-date wrt to references to the humongous object. 5043 // 5044 // Other implementation considerations: 5045 // - never consider object arrays at this time because they would pose 5046 // considerable effort for cleaning up the the remembered sets. This is 5047 // required because stale remembered sets might reference locations that 5048 // are currently allocated into. 5049 uint region_idx = r->hrm_index(); 5050 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 5051 !r->rem_set()->is_empty()) { 5052 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", 5053 region_idx, 5054 (size_t)obj->size() * HeapWordSize, 5055 p2i(r->bottom()), 5056 r->rem_set()->occupied(), 5057 r->rem_set()->strong_code_roots_list_length(), 5058 next_bitmap->isMarked(r->bottom()), 5059 g1h->is_humongous_reclaim_candidate(region_idx), 5060 obj->is_typeArray() 5061 ); 5062 return false; 5063 } 5064 5065 guarantee(obj->is_typeArray(), 5066 "Only eagerly reclaiming type arrays is supported, but the object " 5067 PTR_FORMAT " is not.", p2i(r->bottom())); 5068 5069 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", 5070 region_idx, 5071 (size_t)obj->size() * HeapWordSize, 5072 p2i(r->bottom()), 5073 r->rem_set()->occupied(), 5074 r->rem_set()->strong_code_roots_list_length(), 5075 next_bitmap->isMarked(r->bottom()), 5076 g1h->is_humongous_reclaim_candidate(region_idx), 5077 obj->is_typeArray() 5078 ); 5079 5080 // Need to clear mark bit of the humongous object if already set. 5081 if (next_bitmap->isMarked(r->bottom())) { 5082 next_bitmap->clear(r->bottom()); 5083 } 5084 do { 5085 HeapRegion* next = g1h->next_region_in_humongous(r); 5086 _freed_bytes += r->used(); 5087 r->set_containing_set(NULL); 5088 _humongous_regions_removed++; 5089 g1h->free_humongous_region(r, _free_region_list, false); 5090 r = next; 5091 } while (r != NULL); 5092 5093 return false; 5094 } 5095 5096 uint humongous_free_count() { 5097 return _humongous_regions_removed; 5098 } 5099 5100 size_t bytes_freed() const { 5101 return _freed_bytes; 5102 } 5103 }; 5104 5105 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 5106 assert_at_safepoint(true); 5107 5108 if (!G1EagerReclaimHumongousObjects || 5109 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 5110 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 5111 return; 5112 } 5113 5114 double start_time = os::elapsedTime(); 5115 5116 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 5117 5118 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 5119 heap_region_iterate(&cl); 5120 5121 remove_from_old_sets(0, cl.humongous_free_count()); 5122 5123 G1HRPrinter* hrp = hr_printer(); 5124 if (hrp->is_active()) { 5125 FreeRegionListIterator iter(&local_cleanup_list); 5126 while (iter.more_available()) { 5127 HeapRegion* hr = iter.get_next(); 5128 hrp->cleanup(hr); 5129 } 5130 } 5131 5132 prepend_to_freelist(&local_cleanup_list); 5133 decrement_summary_bytes(cl.bytes_freed()); 5134 5135 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 5136 cl.humongous_free_count()); 5137 } 5138 5139 // This routine is similar to the above but does not record 5140 // any policy statistics or update free lists; we are abandoning 5141 // the current incremental collection set in preparation of a 5142 // full collection. After the full GC we will start to build up 5143 // the incremental collection set again. 5144 // This is only called when we're doing a full collection 5145 // and is immediately followed by the tearing down of the young list. 5146 5147 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 5148 HeapRegion* cur = cs_head; 5149 5150 while (cur != NULL) { 5151 HeapRegion* next = cur->next_in_collection_set(); 5152 assert(cur->in_collection_set(), "bad CS"); 5153 cur->set_next_in_collection_set(NULL); 5154 clear_in_cset(cur); 5155 cur->set_young_index_in_cset(-1); 5156 cur = next; 5157 } 5158 } 5159 5160 void G1CollectedHeap::set_free_regions_coming() { 5161 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming"); 5162 5163 assert(!free_regions_coming(), "pre-condition"); 5164 _free_regions_coming = true; 5165 } 5166 5167 void G1CollectedHeap::reset_free_regions_coming() { 5168 assert(free_regions_coming(), "pre-condition"); 5169 5170 { 5171 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5172 _free_regions_coming = false; 5173 SecondaryFreeList_lock->notify_all(); 5174 } 5175 5176 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming"); 5177 } 5178 5179 void G1CollectedHeap::wait_while_free_regions_coming() { 5180 // Most of the time we won't have to wait, so let's do a quick test 5181 // first before we take the lock. 5182 if (!free_regions_coming()) { 5183 return; 5184 } 5185 5186 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions"); 5187 5188 { 5189 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5190 while (free_regions_coming()) { 5191 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 5192 } 5193 } 5194 5195 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions"); 5196 } 5197 5198 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 5199 return _allocator->is_retained_old_region(hr); 5200 } 5201 5202 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 5203 _young_list->push_region(hr); 5204 } 5205 5206 class NoYoungRegionsClosure: public HeapRegionClosure { 5207 private: 5208 bool _success; 5209 public: 5210 NoYoungRegionsClosure() : _success(true) { } 5211 bool doHeapRegion(HeapRegion* r) { 5212 if (r->is_young()) { 5213 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 5214 p2i(r->bottom()), p2i(r->end())); 5215 _success = false; 5216 } 5217 return false; 5218 } 5219 bool success() { return _success; } 5220 }; 5221 5222 bool G1CollectedHeap::check_young_list_empty(bool check_heap) { 5223 bool ret = _young_list->check_list_empty(); 5224 5225 if (check_heap) { 5226 NoYoungRegionsClosure closure; 5227 heap_region_iterate(&closure); 5228 ret = ret && closure.success(); 5229 } 5230 5231 return ret; 5232 } 5233 5234 class TearDownRegionSetsClosure : public HeapRegionClosure { 5235 private: 5236 HeapRegionSet *_old_set; 5237 5238 public: 5239 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 5240 5241 bool doHeapRegion(HeapRegion* r) { 5242 if (r->is_old()) { 5243 _old_set->remove(r); 5244 } else { 5245 // We ignore free regions, we'll empty the free list afterwards. 5246 // We ignore young regions, we'll empty the young list afterwards. 5247 // We ignore humongous regions, we're not tearing down the 5248 // humongous regions set. 5249 assert(r->is_free() || r->is_young() || r->is_humongous(), 5250 "it cannot be another type"); 5251 } 5252 return false; 5253 } 5254 5255 ~TearDownRegionSetsClosure() { 5256 assert(_old_set->is_empty(), "post-condition"); 5257 } 5258 }; 5259 5260 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 5261 assert_at_safepoint(true /* should_be_vm_thread */); 5262 5263 if (!free_list_only) { 5264 TearDownRegionSetsClosure cl(&_old_set); 5265 heap_region_iterate(&cl); 5266 5267 // Note that emptying the _young_list is postponed and instead done as 5268 // the first step when rebuilding the regions sets again. The reason for 5269 // this is that during a full GC string deduplication needs to know if 5270 // a collected region was young or old when the full GC was initiated. 5271 } 5272 _hrm.remove_all_free_regions(); 5273 } 5274 5275 void G1CollectedHeap::increase_used(size_t bytes) { 5276 _summary_bytes_used += bytes; 5277 } 5278 5279 void G1CollectedHeap::decrease_used(size_t bytes) { 5280 assert(_summary_bytes_used >= bytes, 5281 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 5282 _summary_bytes_used, bytes); 5283 _summary_bytes_used -= bytes; 5284 } 5285 5286 void G1CollectedHeap::set_used(size_t bytes) { 5287 _summary_bytes_used = bytes; 5288 } 5289 5290 class RebuildRegionSetsClosure : public HeapRegionClosure { 5291 private: 5292 bool _free_list_only; 5293 HeapRegionSet* _old_set; 5294 HeapRegionManager* _hrm; 5295 size_t _total_used; 5296 5297 public: 5298 RebuildRegionSetsClosure(bool free_list_only, 5299 HeapRegionSet* old_set, HeapRegionManager* hrm) : 5300 _free_list_only(free_list_only), 5301 _old_set(old_set), _hrm(hrm), _total_used(0) { 5302 assert(_hrm->num_free_regions() == 0, "pre-condition"); 5303 if (!free_list_only) { 5304 assert(_old_set->is_empty(), "pre-condition"); 5305 } 5306 } 5307 5308 bool doHeapRegion(HeapRegion* r) { 5309 if (r->is_empty()) { 5310 // Add free regions to the free list 5311 r->set_free(); 5312 r->set_allocation_context(AllocationContext::system()); 5313 _hrm->insert_into_free_list(r); 5314 } else if (!_free_list_only) { 5315 assert(!r->is_young(), "we should not come across young regions"); 5316 5317 if (r->is_humongous()) { 5318 // We ignore humongous regions. We left the humongous set unchanged. 5319 } else { 5320 // Objects that were compacted would have ended up on regions 5321 // that were previously old or free. Archive regions (which are 5322 // old) will not have been touched. 5323 assert(r->is_free() || r->is_old(), "invariant"); 5324 // We now consider them old, so register as such. Leave 5325 // archive regions set that way, however, while still adding 5326 // them to the old set. 5327 if (!r->is_archive()) { 5328 r->set_old(); 5329 } 5330 _old_set->add(r); 5331 } 5332 _total_used += r->used(); 5333 } 5334 5335 return false; 5336 } 5337 5338 size_t total_used() { 5339 return _total_used; 5340 } 5341 }; 5342 5343 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 5344 assert_at_safepoint(true /* should_be_vm_thread */); 5345 5346 if (!free_list_only) { 5347 _young_list->empty_list(); 5348 } 5349 5350 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 5351 heap_region_iterate(&cl); 5352 5353 if (!free_list_only) { 5354 set_used(cl.total_used()); 5355 if (_archive_allocator != NULL) { 5356 _archive_allocator->clear_used(); 5357 } 5358 } 5359 assert(used_unlocked() == recalculate_used(), 5360 "inconsistent used_unlocked(), " 5361 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 5362 used_unlocked(), recalculate_used()); 5363 } 5364 5365 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 5366 _refine_cte_cl->set_concurrent(concurrent); 5367 } 5368 5369 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 5370 HeapRegion* hr = heap_region_containing(p); 5371 return hr->is_in(p); 5372 } 5373 5374 // Methods for the mutator alloc region 5375 5376 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 5377 bool force) { 5378 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 5379 assert(!force || g1_policy()->can_expand_young_list(), 5380 "if force is true we should be able to expand the young list"); 5381 bool young_list_full = g1_policy()->is_young_list_full(); 5382 if (force || !young_list_full) { 5383 HeapRegion* new_alloc_region = new_region(word_size, 5384 false /* is_old */, 5385 false /* do_expand */); 5386 if (new_alloc_region != NULL) { 5387 set_region_short_lived_locked(new_alloc_region); 5388 _hr_printer.alloc(new_alloc_region, young_list_full); 5389 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 5390 return new_alloc_region; 5391 } 5392 } 5393 return NULL; 5394 } 5395 5396 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 5397 size_t allocated_bytes) { 5398 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 5399 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 5400 5401 collection_set()->add_eden_region(alloc_region); 5402 increase_used(allocated_bytes); 5403 _hr_printer.retire(alloc_region); 5404 // We update the eden sizes here, when the region is retired, 5405 // instead of when it's allocated, since this is the point that its 5406 // used space has been recored in _summary_bytes_used. 5407 g1mm()->update_eden_size(); 5408 } 5409 5410 // Methods for the GC alloc regions 5411 5412 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 5413 uint count, 5414 InCSetState dest) { 5415 assert(FreeList_lock->owned_by_self(), "pre-condition"); 5416 5417 if (count < g1_policy()->max_regions(dest)) { 5418 const bool is_survivor = (dest.is_young()); 5419 HeapRegion* new_alloc_region = new_region(word_size, 5420 !is_survivor, 5421 true /* do_expand */); 5422 if (new_alloc_region != NULL) { 5423 // We really only need to do this for old regions given that we 5424 // should never scan survivors. But it doesn't hurt to do it 5425 // for survivors too. 5426 new_alloc_region->record_timestamp(); 5427 if (is_survivor) { 5428 new_alloc_region->set_survivor(); 5429 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 5430 } else { 5431 new_alloc_region->set_old(); 5432 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 5433 } 5434 _hr_printer.alloc(new_alloc_region); 5435 bool during_im = collector_state()->during_initial_mark_pause(); 5436 new_alloc_region->note_start_of_copying(during_im); 5437 return new_alloc_region; 5438 } 5439 } 5440 return NULL; 5441 } 5442 5443 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 5444 size_t allocated_bytes, 5445 InCSetState dest) { 5446 bool during_im = collector_state()->during_initial_mark_pause(); 5447 alloc_region->note_end_of_copying(during_im); 5448 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 5449 if (dest.is_young()) { 5450 young_list()->add_survivor_region(alloc_region); 5451 } else { 5452 _old_set.add(alloc_region); 5453 } 5454 _hr_printer.retire(alloc_region); 5455 } 5456 5457 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 5458 bool expanded = false; 5459 uint index = _hrm.find_highest_free(&expanded); 5460 5461 if (index != G1_NO_HRM_INDEX) { 5462 if (expanded) { 5463 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 5464 HeapRegion::GrainWords * HeapWordSize); 5465 } 5466 _hrm.allocate_free_regions_starting_at(index, 1); 5467 return region_at(index); 5468 } 5469 return NULL; 5470 } 5471 5472 // Optimized nmethod scanning 5473 5474 class RegisterNMethodOopClosure: public OopClosure { 5475 G1CollectedHeap* _g1h; 5476 nmethod* _nm; 5477 5478 template <class T> void do_oop_work(T* p) { 5479 T heap_oop = oopDesc::load_heap_oop(p); 5480 if (!oopDesc::is_null(heap_oop)) { 5481 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 5482 HeapRegion* hr = _g1h->heap_region_containing(obj); 5483 assert(!hr->is_continues_humongous(), 5484 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 5485 " starting at " HR_FORMAT, 5486 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 5487 5488 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 5489 hr->add_strong_code_root_locked(_nm); 5490 } 5491 } 5492 5493 public: 5494 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 5495 _g1h(g1h), _nm(nm) {} 5496 5497 void do_oop(oop* p) { do_oop_work(p); } 5498 void do_oop(narrowOop* p) { do_oop_work(p); } 5499 }; 5500 5501 class UnregisterNMethodOopClosure: public OopClosure { 5502 G1CollectedHeap* _g1h; 5503 nmethod* _nm; 5504 5505 template <class T> void do_oop_work(T* p) { 5506 T heap_oop = oopDesc::load_heap_oop(p); 5507 if (!oopDesc::is_null(heap_oop)) { 5508 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 5509 HeapRegion* hr = _g1h->heap_region_containing(obj); 5510 assert(!hr->is_continues_humongous(), 5511 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 5512 " starting at " HR_FORMAT, 5513 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 5514 5515 hr->remove_strong_code_root(_nm); 5516 } 5517 } 5518 5519 public: 5520 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 5521 _g1h(g1h), _nm(nm) {} 5522 5523 void do_oop(oop* p) { do_oop_work(p); } 5524 void do_oop(narrowOop* p) { do_oop_work(p); } 5525 }; 5526 5527 void G1CollectedHeap::register_nmethod(nmethod* nm) { 5528 CollectedHeap::register_nmethod(nm); 5529 5530 guarantee(nm != NULL, "sanity"); 5531 RegisterNMethodOopClosure reg_cl(this, nm); 5532 nm->oops_do(®_cl); 5533 } 5534 5535 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 5536 CollectedHeap::unregister_nmethod(nm); 5537 5538 guarantee(nm != NULL, "sanity"); 5539 UnregisterNMethodOopClosure reg_cl(this, nm); 5540 nm->oops_do(®_cl, true); 5541 } 5542 5543 void G1CollectedHeap::purge_code_root_memory() { 5544 double purge_start = os::elapsedTime(); 5545 G1CodeRootSet::purge(); 5546 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 5547 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 5548 } 5549 5550 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 5551 G1CollectedHeap* _g1h; 5552 5553 public: 5554 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 5555 _g1h(g1h) {} 5556 5557 void do_code_blob(CodeBlob* cb) { 5558 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 5559 if (nm == NULL) { 5560 return; 5561 } 5562 5563 if (ScavengeRootsInCode) { 5564 _g1h->register_nmethod(nm); 5565 } 5566 } 5567 }; 5568 5569 void G1CollectedHeap::rebuild_strong_code_roots() { 5570 RebuildStrongCodeRootClosure blob_cl(this); 5571 CodeCache::blobs_do(&blob_cl); 5572 }