1 /* 2 * Copyright (c) 2001, 2015, 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 "code/codeCache.hpp" 29 #include "code/icBuffer.hpp" 30 #include "gc/g1/bufferingOopClosure.hpp" 31 #include "gc/g1/concurrentG1Refine.hpp" 32 #include "gc/g1/concurrentG1RefineThread.hpp" 33 #include "gc/g1/concurrentMarkThread.inline.hpp" 34 #include "gc/g1/g1Allocator.inline.hpp" 35 #include "gc/g1/g1CollectedHeap.inline.hpp" 36 #include "gc/g1/g1CollectorPolicy.hpp" 37 #include "gc/g1/g1CollectorState.hpp" 38 #include "gc/g1/g1ErgoVerbose.hpp" 39 #include "gc/g1/g1EvacStats.inline.hpp" 40 #include "gc/g1/g1GCPhaseTimes.hpp" 41 #include "gc/g1/g1Log.hpp" 42 #include "gc/g1/g1MarkSweep.hpp" 43 #include "gc/g1/g1OopClosures.inline.hpp" 44 #include "gc/g1/g1ParScanThreadState.inline.hpp" 45 #include "gc/g1/g1RegionToSpaceMapper.hpp" 46 #include "gc/g1/g1RemSet.inline.hpp" 47 #include "gc/g1/g1RootClosures.hpp" 48 #include "gc/g1/g1RootProcessor.hpp" 49 #include "gc/g1/g1StringDedup.hpp" 50 #include "gc/g1/g1YCTypes.hpp" 51 #include "gc/g1/heapRegion.inline.hpp" 52 #include "gc/g1/heapRegionRemSet.hpp" 53 #include "gc/g1/heapRegionSet.inline.hpp" 54 #include "gc/g1/suspendibleThreadSet.hpp" 55 #include "gc/g1/vm_operations_g1.hpp" 56 #include "gc/shared/gcHeapSummary.hpp" 57 #include "gc/shared/gcId.hpp" 58 #include "gc/shared/gcLocker.inline.hpp" 59 #include "gc/shared/gcTimer.hpp" 60 #include "gc/shared/gcTrace.hpp" 61 #include "gc/shared/gcTraceTime.hpp" 62 #include "gc/shared/generationSpec.hpp" 63 #include "gc/shared/isGCActiveMark.hpp" 64 #include "gc/shared/referenceProcessor.hpp" 65 #include "gc/shared/taskqueue.inline.hpp" 66 #include "memory/allocation.hpp" 67 #include "memory/iterator.hpp" 68 #include "oops/oop.inline.hpp" 69 #include "runtime/atomic.inline.hpp" 70 #include "runtime/init.hpp" 71 #include "runtime/orderAccess.inline.hpp" 72 #include "runtime/vmThread.hpp" 73 #include "utilities/globalDefinitions.hpp" 74 #include "utilities/stack.inline.hpp" 75 76 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 77 78 // INVARIANTS/NOTES 79 // 80 // All allocation activity covered by the G1CollectedHeap interface is 81 // serialized by acquiring the HeapLock. This happens in mem_allocate 82 // and allocate_new_tlab, which are the "entry" points to the 83 // allocation code from the rest of the JVM. (Note that this does not 84 // apply to TLAB allocation, which is not part of this interface: it 85 // is done by clients of this interface.) 86 87 // Local to this file. 88 89 class RefineCardTableEntryClosure: public CardTableEntryClosure { 90 bool _concurrent; 91 public: 92 RefineCardTableEntryClosure() : _concurrent(true) { } 93 94 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 95 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 96 // This path is executed by the concurrent refine or mutator threads, 97 // concurrently, and so we do not care if card_ptr contains references 98 // that point into the collection set. 99 assert(!oops_into_cset, "should be"); 100 101 if (_concurrent && SuspendibleThreadSet::should_yield()) { 102 // Caller will actually yield. 103 return false; 104 } 105 // Otherwise, we finished successfully; return true. 106 return true; 107 } 108 109 void set_concurrent(bool b) { _concurrent = b; } 110 }; 111 112 113 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 114 private: 115 size_t _num_dirtied; 116 G1CollectedHeap* _g1h; 117 G1SATBCardTableLoggingModRefBS* _g1_bs; 118 119 HeapRegion* region_for_card(jbyte* card_ptr) const { 120 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr)); 121 } 122 123 bool will_become_free(HeapRegion* hr) const { 124 // A region will be freed by free_collection_set if the region is in the 125 // collection set and has not had an evacuation failure. 126 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 127 } 128 129 public: 130 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(), 131 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { } 132 133 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 134 HeapRegion* hr = region_for_card(card_ptr); 135 136 // Should only dirty cards in regions that won't be freed. 137 if (!will_become_free(hr)) { 138 *card_ptr = CardTableModRefBS::dirty_card_val(); 139 _num_dirtied++; 140 } 141 142 return true; 143 } 144 145 size_t num_dirtied() const { return _num_dirtied; } 146 }; 147 148 149 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 150 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 151 } 152 153 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 154 // The from card cache is not the memory that is actually committed. So we cannot 155 // take advantage of the zero_filled parameter. 156 reset_from_card_cache(start_idx, num_regions); 157 } 158 159 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 160 { 161 // Claim the right to put the region on the dirty cards region list 162 // by installing a self pointer. 163 HeapRegion* next = hr->get_next_dirty_cards_region(); 164 if (next == NULL) { 165 HeapRegion* res = (HeapRegion*) 166 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 167 NULL); 168 if (res == NULL) { 169 HeapRegion* head; 170 do { 171 // Put the region to the dirty cards region list. 172 head = _dirty_cards_region_list; 173 next = (HeapRegion*) 174 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 175 if (next == head) { 176 assert(hr->get_next_dirty_cards_region() == hr, 177 "hr->get_next_dirty_cards_region() != hr"); 178 if (next == NULL) { 179 // The last region in the list points to itself. 180 hr->set_next_dirty_cards_region(hr); 181 } else { 182 hr->set_next_dirty_cards_region(next); 183 } 184 } 185 } while (next != head); 186 } 187 } 188 } 189 190 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 191 { 192 HeapRegion* head; 193 HeapRegion* hr; 194 do { 195 head = _dirty_cards_region_list; 196 if (head == NULL) { 197 return NULL; 198 } 199 HeapRegion* new_head = head->get_next_dirty_cards_region(); 200 if (head == new_head) { 201 // The last region. 202 new_head = NULL; 203 } 204 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 205 head); 206 } while (hr != head); 207 assert(hr != NULL, "invariant"); 208 hr->set_next_dirty_cards_region(NULL); 209 return hr; 210 } 211 212 // Returns true if the reference points to an object that 213 // can move in an incremental collection. 214 bool G1CollectedHeap::is_scavengable(const void* p) { 215 HeapRegion* hr = heap_region_containing(p); 216 return !hr->is_pinned(); 217 } 218 219 // Private methods. 220 221 HeapRegion* 222 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 223 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 224 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 225 if (!_secondary_free_list.is_empty()) { 226 if (G1ConcRegionFreeingVerbose) { 227 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 228 "secondary_free_list has %u entries", 229 _secondary_free_list.length()); 230 } 231 // It looks as if there are free regions available on the 232 // secondary_free_list. Let's move them to the free_list and try 233 // again to allocate from it. 234 append_secondary_free_list(); 235 236 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 237 "empty we should have moved at least one entry to the free_list"); 238 HeapRegion* res = _hrm.allocate_free_region(is_old); 239 if (G1ConcRegionFreeingVerbose) { 240 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 241 "allocated " HR_FORMAT " from secondary_free_list", 242 HR_FORMAT_PARAMS(res)); 243 } 244 return res; 245 } 246 247 // Wait here until we get notified either when (a) there are no 248 // more free regions coming or (b) some regions have been moved on 249 // the secondary_free_list. 250 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 251 } 252 253 if (G1ConcRegionFreeingVerbose) { 254 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 255 "could not allocate from secondary_free_list"); 256 } 257 return NULL; 258 } 259 260 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 261 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 262 "the only time we use this to allocate a humongous region is " 263 "when we are allocating a single humongous region"); 264 265 HeapRegion* res; 266 if (G1StressConcRegionFreeing) { 267 if (!_secondary_free_list.is_empty()) { 268 if (G1ConcRegionFreeingVerbose) { 269 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 270 "forced to look at the secondary_free_list"); 271 } 272 res = new_region_try_secondary_free_list(is_old); 273 if (res != NULL) { 274 return res; 275 } 276 } 277 } 278 279 res = _hrm.allocate_free_region(is_old); 280 281 if (res == NULL) { 282 if (G1ConcRegionFreeingVerbose) { 283 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 284 "res == NULL, trying the secondary_free_list"); 285 } 286 res = new_region_try_secondary_free_list(is_old); 287 } 288 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 289 // Currently, only attempts to allocate GC alloc regions set 290 // do_expand to true. So, we should only reach here during a 291 // safepoint. If this assumption changes we might have to 292 // reconsider the use of _expand_heap_after_alloc_failure. 293 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 294 295 ergo_verbose1(ErgoHeapSizing, 296 "attempt heap expansion", 297 ergo_format_reason("region allocation request failed") 298 ergo_format_byte("allocation request"), 299 word_size * HeapWordSize); 300 if (expand(word_size * HeapWordSize)) { 301 // Given that expand() succeeded in expanding the heap, and we 302 // always expand the heap by an amount aligned to the heap 303 // region size, the free list should in theory not be empty. 304 // In either case allocate_free_region() will check for NULL. 305 res = _hrm.allocate_free_region(is_old); 306 } else { 307 _expand_heap_after_alloc_failure = false; 308 } 309 } 310 return res; 311 } 312 313 HeapWord* 314 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 315 uint num_regions, 316 size_t word_size, 317 AllocationContext_t context) { 318 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 319 assert(is_humongous(word_size), "word_size should be humongous"); 320 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 321 322 // Index of last region in the series. 323 uint last = first + num_regions - 1; 324 325 // We need to initialize the region(s) we just discovered. This is 326 // a bit tricky given that it can happen concurrently with 327 // refinement threads refining cards on these regions and 328 // potentially wanting to refine the BOT as they are scanning 329 // those cards (this can happen shortly after a cleanup; see CR 330 // 6991377). So we have to set up the region(s) carefully and in 331 // a specific order. 332 333 // The word size sum of all the regions we will allocate. 334 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 335 assert(word_size <= word_size_sum, "sanity"); 336 337 // This will be the "starts humongous" region. 338 HeapRegion* first_hr = region_at(first); 339 // The header of the new object will be placed at the bottom of 340 // the first region. 341 HeapWord* new_obj = first_hr->bottom(); 342 // This will be the new top of the new object. 343 HeapWord* obj_top = new_obj + word_size; 344 345 // First, we need to zero the header of the space that we will be 346 // allocating. When we update top further down, some refinement 347 // threads might try to scan the region. By zeroing the header we 348 // ensure that any thread that will try to scan the region will 349 // come across the zero klass word and bail out. 350 // 351 // NOTE: It would not have been correct to have used 352 // CollectedHeap::fill_with_object() and make the space look like 353 // an int array. The thread that is doing the allocation will 354 // later update the object header to a potentially different array 355 // type and, for a very short period of time, the klass and length 356 // fields will be inconsistent. This could cause a refinement 357 // thread to calculate the object size incorrectly. 358 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 359 360 // How many words we use for filler objects. 361 size_t word_fill_size = word_size_sum - word_size; 362 363 // How many words memory we "waste" which cannot hold a filler object. 364 size_t words_not_fillable = 0; 365 366 if (word_fill_size >= min_fill_size()) { 367 fill_with_objects(obj_top, word_fill_size); 368 } else if (word_fill_size > 0) { 369 // We have space to fill, but we cannot fit an object there. 370 words_not_fillable = word_fill_size; 371 word_fill_size = 0; 372 } 373 374 // We will set up the first region as "starts humongous". This 375 // will also update the BOT covering all the regions to reflect 376 // that there is a single object that starts at the bottom of the 377 // first region. 378 first_hr->set_starts_humongous(obj_top, word_fill_size); 379 first_hr->set_allocation_context(context); 380 // Then, if there are any, we will set up the "continues 381 // humongous" regions. 382 HeapRegion* hr = NULL; 383 for (uint i = first + 1; i <= last; ++i) { 384 hr = region_at(i); 385 hr->set_continues_humongous(first_hr); 386 hr->set_allocation_context(context); 387 } 388 389 // Up to this point no concurrent thread would have been able to 390 // do any scanning on any region in this series. All the top 391 // fields still point to bottom, so the intersection between 392 // [bottom,top] and [card_start,card_end] will be empty. Before we 393 // update the top fields, we'll do a storestore to make sure that 394 // no thread sees the update to top before the zeroing of the 395 // object header and the BOT initialization. 396 OrderAccess::storestore(); 397 398 // Now, we will update the top fields of the "continues humongous" 399 // regions except the last one. 400 for (uint i = first; i < last; ++i) { 401 hr = region_at(i); 402 hr->set_top(hr->end()); 403 } 404 405 hr = region_at(last); 406 // If we cannot fit a filler object, we must set top to the end 407 // of the humongous object, otherwise we cannot iterate the heap 408 // and the BOT will not be complete. 409 hr->set_top(hr->end() - words_not_fillable); 410 411 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 412 "obj_top should be in last region"); 413 414 check_bitmaps("Humongous Region Allocation", first_hr); 415 416 assert(words_not_fillable == 0 || 417 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 418 "Miscalculation in humongous allocation"); 419 420 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 421 422 for (uint i = first; i <= last; ++i) { 423 hr = region_at(i); 424 _humongous_set.add(hr); 425 if (i == first) { 426 _hr_printer.alloc(G1HRPrinter::StartsHumongous, hr, hr->top()); 427 } else { 428 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->top()); 429 } 430 } 431 432 return new_obj; 433 } 434 435 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 436 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 437 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 438 } 439 440 // If could fit into free regions w/o expansion, try. 441 // Otherwise, if can expand, do so. 442 // Otherwise, if using ex regions might help, try with ex given back. 443 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 444 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 445 446 verify_region_sets_optional(); 447 448 uint first = G1_NO_HRM_INDEX; 449 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 450 451 if (obj_regions == 1) { 452 // Only one region to allocate, try to use a fast path by directly allocating 453 // from the free lists. Do not try to expand here, we will potentially do that 454 // later. 455 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 456 if (hr != NULL) { 457 first = hr->hrm_index(); 458 } 459 } else { 460 // We can't allocate humongous regions spanning more than one region while 461 // cleanupComplete() is running, since some of the regions we find to be 462 // empty might not yet be added to the free list. It is not straightforward 463 // to know in which list they are on so that we can remove them. We only 464 // need to do this if we need to allocate more than one region to satisfy the 465 // current humongous allocation request. If we are only allocating one region 466 // we use the one-region region allocation code (see above), that already 467 // potentially waits for regions from the secondary free list. 468 wait_while_free_regions_coming(); 469 append_secondary_free_list_if_not_empty_with_lock(); 470 471 // Policy: Try only empty regions (i.e. already committed first). Maybe we 472 // are lucky enough to find some. 473 first = _hrm.find_contiguous_only_empty(obj_regions); 474 if (first != G1_NO_HRM_INDEX) { 475 _hrm.allocate_free_regions_starting_at(first, obj_regions); 476 } 477 } 478 479 if (first == G1_NO_HRM_INDEX) { 480 // Policy: We could not find enough regions for the humongous object in the 481 // free list. Look through the heap to find a mix of free and uncommitted regions. 482 // If so, try expansion. 483 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 484 if (first != G1_NO_HRM_INDEX) { 485 // We found something. Make sure these regions are committed, i.e. expand 486 // the heap. Alternatively we could do a defragmentation GC. 487 ergo_verbose1(ErgoHeapSizing, 488 "attempt heap expansion", 489 ergo_format_reason("humongous allocation request failed") 490 ergo_format_byte("allocation request"), 491 word_size * HeapWordSize); 492 493 _hrm.expand_at(first, obj_regions); 494 g1_policy()->record_new_heap_size(num_regions()); 495 496 #ifdef ASSERT 497 for (uint i = first; i < first + obj_regions; ++i) { 498 HeapRegion* hr = region_at(i); 499 assert(hr->is_free(), "sanity"); 500 assert(hr->is_empty(), "sanity"); 501 assert(is_on_master_free_list(hr), "sanity"); 502 } 503 #endif 504 _hrm.allocate_free_regions_starting_at(first, obj_regions); 505 } else { 506 // Policy: Potentially trigger a defragmentation GC. 507 } 508 } 509 510 HeapWord* result = NULL; 511 if (first != G1_NO_HRM_INDEX) { 512 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 513 word_size, context); 514 assert(result != NULL, "it should always return a valid result"); 515 516 // A successful humongous object allocation changes the used space 517 // information of the old generation so we need to recalculate the 518 // sizes and update the jstat counters here. 519 g1mm()->update_sizes(); 520 } 521 522 verify_region_sets_optional(); 523 524 return result; 525 } 526 527 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 528 assert_heap_not_locked_and_not_at_safepoint(); 529 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 530 531 uint dummy_gc_count_before; 532 uint dummy_gclocker_retry_count = 0; 533 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 534 } 535 536 HeapWord* 537 G1CollectedHeap::mem_allocate(size_t word_size, 538 bool* gc_overhead_limit_was_exceeded) { 539 assert_heap_not_locked_and_not_at_safepoint(); 540 541 // Loop until the allocation is satisfied, or unsatisfied after GC. 542 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 543 uint gc_count_before; 544 545 HeapWord* result = NULL; 546 if (!is_humongous(word_size)) { 547 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 548 } else { 549 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 550 } 551 if (result != NULL) { 552 return result; 553 } 554 555 // Create the garbage collection operation... 556 VM_G1CollectForAllocation op(gc_count_before, word_size); 557 op.set_allocation_context(AllocationContext::current()); 558 559 // ...and get the VM thread to execute it. 560 VMThread::execute(&op); 561 562 if (op.prologue_succeeded() && op.pause_succeeded()) { 563 // If the operation was successful we'll return the result even 564 // if it is NULL. If the allocation attempt failed immediately 565 // after a Full GC, it's unlikely we'll be able to allocate now. 566 HeapWord* result = op.result(); 567 if (result != NULL && !is_humongous(word_size)) { 568 // Allocations that take place on VM operations do not do any 569 // card dirtying and we have to do it here. We only have to do 570 // this for non-humongous allocations, though. 571 dirty_young_block(result, word_size); 572 } 573 return result; 574 } else { 575 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 576 return NULL; 577 } 578 assert(op.result() == NULL, 579 "the result should be NULL if the VM op did not succeed"); 580 } 581 582 // Give a warning if we seem to be looping forever. 583 if ((QueuedAllocationWarningCount > 0) && 584 (try_count % QueuedAllocationWarningCount == 0)) { 585 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 586 } 587 } 588 589 ShouldNotReachHere(); 590 return NULL; 591 } 592 593 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 594 AllocationContext_t context, 595 uint* gc_count_before_ret, 596 uint* gclocker_retry_count_ret) { 597 // Make sure you read the note in attempt_allocation_humongous(). 598 599 assert_heap_not_locked_and_not_at_safepoint(); 600 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 601 "be called for humongous allocation requests"); 602 603 // We should only get here after the first-level allocation attempt 604 // (attempt_allocation()) failed to allocate. 605 606 // We will loop until a) we manage to successfully perform the 607 // allocation or b) we successfully schedule a collection which 608 // fails to perform the allocation. b) is the only case when we'll 609 // return NULL. 610 HeapWord* result = NULL; 611 for (int try_count = 1; /* we'll return */; try_count += 1) { 612 bool should_try_gc; 613 uint gc_count_before; 614 615 { 616 MutexLockerEx x(Heap_lock); 617 result = _allocator->attempt_allocation_locked(word_size, context); 618 if (result != NULL) { 619 return result; 620 } 621 622 if (GC_locker::is_active_and_needs_gc()) { 623 if (g1_policy()->can_expand_young_list()) { 624 // No need for an ergo verbose message here, 625 // can_expand_young_list() does this when it returns true. 626 result = _allocator->attempt_allocation_force(word_size, context); 627 if (result != NULL) { 628 return result; 629 } 630 } 631 should_try_gc = false; 632 } else { 633 // The GCLocker may not be active but the GCLocker initiated 634 // GC may not yet have been performed (GCLocker::needs_gc() 635 // returns true). In this case we do not try this GC and 636 // wait until the GCLocker initiated GC is performed, and 637 // then retry the allocation. 638 if (GC_locker::needs_gc()) { 639 should_try_gc = false; 640 } else { 641 // Read the GC count while still holding the Heap_lock. 642 gc_count_before = total_collections(); 643 should_try_gc = true; 644 } 645 } 646 } 647 648 if (should_try_gc) { 649 bool succeeded; 650 result = do_collection_pause(word_size, gc_count_before, &succeeded, 651 GCCause::_g1_inc_collection_pause); 652 if (result != NULL) { 653 assert(succeeded, "only way to get back a non-NULL result"); 654 return result; 655 } 656 657 if (succeeded) { 658 // If we get here we successfully scheduled a collection which 659 // failed to allocate. No point in trying to allocate 660 // further. We'll just return NULL. 661 MutexLockerEx x(Heap_lock); 662 *gc_count_before_ret = total_collections(); 663 return NULL; 664 } 665 } else { 666 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 667 MutexLockerEx x(Heap_lock); 668 *gc_count_before_ret = total_collections(); 669 return NULL; 670 } 671 // The GCLocker is either active or the GCLocker initiated 672 // GC has not yet been performed. Stall until it is and 673 // then retry the allocation. 674 GC_locker::stall_until_clear(); 675 (*gclocker_retry_count_ret) += 1; 676 } 677 678 // We can reach here if we were unsuccessful in scheduling a 679 // collection (because another thread beat us to it) or if we were 680 // stalled due to the GC locker. In either can we should retry the 681 // allocation attempt in case another thread successfully 682 // performed a collection and reclaimed enough space. We do the 683 // first attempt (without holding the Heap_lock) here and the 684 // follow-on attempt will be at the start of the next loop 685 // iteration (after taking the Heap_lock). 686 result = _allocator->attempt_allocation(word_size, context); 687 if (result != NULL) { 688 return result; 689 } 690 691 // Give a warning if we seem to be looping forever. 692 if ((QueuedAllocationWarningCount > 0) && 693 (try_count % QueuedAllocationWarningCount == 0)) { 694 warning("G1CollectedHeap::attempt_allocation_slow() " 695 "retries %d times", try_count); 696 } 697 } 698 699 ShouldNotReachHere(); 700 return NULL; 701 } 702 703 void G1CollectedHeap::begin_archive_alloc_range() { 704 assert_at_safepoint(true /* should_be_vm_thread */); 705 if (_archive_allocator == NULL) { 706 _archive_allocator = G1ArchiveAllocator::create_allocator(this); 707 } 708 } 709 710 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 711 // Allocations in archive regions cannot be of a size that would be considered 712 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 713 // may be different at archive-restore time. 714 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 715 } 716 717 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 718 assert_at_safepoint(true /* should_be_vm_thread */); 719 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 720 if (is_archive_alloc_too_large(word_size)) { 721 return NULL; 722 } 723 return _archive_allocator->archive_mem_allocate(word_size); 724 } 725 726 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 727 size_t end_alignment_in_bytes) { 728 assert_at_safepoint(true /* should_be_vm_thread */); 729 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 730 731 // Call complete_archive to do the real work, filling in the MemRegion 732 // array with the archive regions. 733 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 734 delete _archive_allocator; 735 _archive_allocator = NULL; 736 } 737 738 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 739 assert(ranges != NULL, "MemRegion array NULL"); 740 assert(count != 0, "No MemRegions provided"); 741 MemRegion reserved = _hrm.reserved(); 742 for (size_t i = 0; i < count; i++) { 743 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 744 return false; 745 } 746 } 747 return true; 748 } 749 750 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) { 751 assert(!is_init_completed(), "Expect to be called at JVM init time"); 752 assert(ranges != NULL, "MemRegion array NULL"); 753 assert(count != 0, "No MemRegions provided"); 754 MutexLockerEx x(Heap_lock); 755 756 MemRegion reserved = _hrm.reserved(); 757 HeapWord* prev_last_addr = NULL; 758 HeapRegion* prev_last_region = NULL; 759 760 // Temporarily disable pretouching of heap pages. This interface is used 761 // when mmap'ing archived heap data in, so pre-touching is wasted. 762 FlagSetting fs(AlwaysPreTouch, false); 763 764 // Enable archive object checking in G1MarkSweep. We have to let it know 765 // about each archive range, so that objects in those ranges aren't marked. 766 G1MarkSweep::enable_archive_object_check(); 767 768 // For each specified MemRegion range, allocate the corresponding G1 769 // regions and mark them as archive regions. We expect the ranges in 770 // ascending starting address order, without overlap. 771 for (size_t i = 0; i < count; i++) { 772 MemRegion curr_range = ranges[i]; 773 HeapWord* start_address = curr_range.start(); 774 size_t word_size = curr_range.word_size(); 775 HeapWord* last_address = curr_range.last(); 776 size_t commits = 0; 777 778 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 779 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 780 p2i(start_address), p2i(last_address)); 781 guarantee(start_address > prev_last_addr, 782 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 783 p2i(start_address), p2i(prev_last_addr)); 784 prev_last_addr = last_address; 785 786 // Check for ranges that start in the same G1 region in which the previous 787 // range ended, and adjust the start address so we don't try to allocate 788 // the same region again. If the current range is entirely within that 789 // region, skip it, just adjusting the recorded top. 790 HeapRegion* start_region = _hrm.addr_to_region(start_address); 791 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 792 start_address = start_region->end(); 793 if (start_address > last_address) { 794 increase_used(word_size * HeapWordSize); 795 start_region->set_top(last_address + 1); 796 continue; 797 } 798 start_region->set_top(start_address); 799 curr_range = MemRegion(start_address, last_address + 1); 800 start_region = _hrm.addr_to_region(start_address); 801 } 802 803 // Perform the actual region allocation, exiting if it fails. 804 // Then note how much new space we have allocated. 805 if (!_hrm.allocate_containing_regions(curr_range, &commits)) { 806 return false; 807 } 808 increase_used(word_size * HeapWordSize); 809 if (commits != 0) { 810 ergo_verbose1(ErgoHeapSizing, 811 "attempt heap expansion", 812 ergo_format_reason("allocate archive regions") 813 ergo_format_byte("total size"), 814 HeapRegion::GrainWords * HeapWordSize * commits); 815 } 816 817 // Mark each G1 region touched by the range as archive, add it to the old set, 818 // and set the allocation context and top. 819 HeapRegion* curr_region = _hrm.addr_to_region(start_address); 820 HeapRegion* last_region = _hrm.addr_to_region(last_address); 821 prev_last_region = last_region; 822 823 while (curr_region != NULL) { 824 assert(curr_region->is_empty() && !curr_region->is_pinned(), 825 "Region already in use (index %u)", curr_region->hrm_index()); 826 _hr_printer.alloc(curr_region, G1HRPrinter::Archive); 827 curr_region->set_allocation_context(AllocationContext::system()); 828 curr_region->set_archive(); 829 _old_set.add(curr_region); 830 if (curr_region != last_region) { 831 curr_region->set_top(curr_region->end()); 832 curr_region = _hrm.next_region_in_heap(curr_region); 833 } else { 834 curr_region->set_top(last_address + 1); 835 curr_region = NULL; 836 } 837 } 838 839 // Notify mark-sweep of the archive range. 840 G1MarkSweep::set_range_archive(curr_range, true); 841 } 842 return true; 843 } 844 845 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 846 assert(!is_init_completed(), "Expect to be called at JVM init time"); 847 assert(ranges != NULL, "MemRegion array NULL"); 848 assert(count != 0, "No MemRegions provided"); 849 MemRegion reserved = _hrm.reserved(); 850 HeapWord *prev_last_addr = NULL; 851 HeapRegion* prev_last_region = NULL; 852 853 // For each MemRegion, create filler objects, if needed, in the G1 regions 854 // that contain the address range. The address range actually within the 855 // MemRegion will not be modified. That is assumed to have been initialized 856 // elsewhere, probably via an mmap of archived heap data. 857 MutexLockerEx x(Heap_lock); 858 for (size_t i = 0; i < count; i++) { 859 HeapWord* start_address = ranges[i].start(); 860 HeapWord* last_address = ranges[i].last(); 861 862 assert(reserved.contains(start_address) && reserved.contains(last_address), 863 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 864 p2i(start_address), p2i(last_address)); 865 assert(start_address > prev_last_addr, 866 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 867 p2i(start_address), p2i(prev_last_addr)); 868 869 HeapRegion* start_region = _hrm.addr_to_region(start_address); 870 HeapRegion* last_region = _hrm.addr_to_region(last_address); 871 HeapWord* bottom_address = start_region->bottom(); 872 873 // Check for a range beginning in the same region in which the 874 // previous one ended. 875 if (start_region == prev_last_region) { 876 bottom_address = prev_last_addr + 1; 877 } 878 879 // Verify that the regions were all marked as archive regions by 880 // alloc_archive_regions. 881 HeapRegion* curr_region = start_region; 882 while (curr_region != NULL) { 883 guarantee(curr_region->is_archive(), 884 "Expected archive region at index %u", curr_region->hrm_index()); 885 if (curr_region != last_region) { 886 curr_region = _hrm.next_region_in_heap(curr_region); 887 } else { 888 curr_region = NULL; 889 } 890 } 891 892 prev_last_addr = last_address; 893 prev_last_region = last_region; 894 895 // Fill the memory below the allocated range with dummy object(s), 896 // if the region bottom does not match the range start, or if the previous 897 // range ended within the same G1 region, and there is a gap. 898 if (start_address != bottom_address) { 899 size_t fill_size = pointer_delta(start_address, bottom_address); 900 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 901 increase_used(fill_size * HeapWordSize); 902 } 903 } 904 } 905 906 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size, 907 uint* gc_count_before_ret, 908 uint* gclocker_retry_count_ret) { 909 assert_heap_not_locked_and_not_at_safepoint(); 910 assert(!is_humongous(word_size), "attempt_allocation() should not " 911 "be called for humongous allocation requests"); 912 913 AllocationContext_t context = AllocationContext::current(); 914 HeapWord* result = _allocator->attempt_allocation(word_size, context); 915 916 if (result == NULL) { 917 result = attempt_allocation_slow(word_size, 918 context, 919 gc_count_before_ret, 920 gclocker_retry_count_ret); 921 } 922 assert_heap_not_locked(); 923 if (result != NULL) { 924 dirty_young_block(result, word_size); 925 } 926 return result; 927 } 928 929 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 930 assert(!is_init_completed(), "Expect to be called at JVM init time"); 931 assert(ranges != NULL, "MemRegion array NULL"); 932 assert(count != 0, "No MemRegions provided"); 933 MemRegion reserved = _hrm.reserved(); 934 HeapWord* prev_last_addr = NULL; 935 HeapRegion* prev_last_region = NULL; 936 size_t size_used = 0; 937 size_t uncommitted_regions = 0; 938 939 // For each Memregion, free the G1 regions that constitute it, and 940 // notify mark-sweep that the range is no longer to be considered 'archive.' 941 MutexLockerEx x(Heap_lock); 942 for (size_t i = 0; i < count; i++) { 943 HeapWord* start_address = ranges[i].start(); 944 HeapWord* last_address = ranges[i].last(); 945 946 assert(reserved.contains(start_address) && reserved.contains(last_address), 947 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 948 p2i(start_address), p2i(last_address)); 949 assert(start_address > prev_last_addr, 950 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 951 p2i(start_address), p2i(prev_last_addr)); 952 size_used += ranges[i].byte_size(); 953 prev_last_addr = last_address; 954 955 HeapRegion* start_region = _hrm.addr_to_region(start_address); 956 HeapRegion* last_region = _hrm.addr_to_region(last_address); 957 958 // Check for ranges that start in the same G1 region in which the previous 959 // range ended, and adjust the start address so we don't try to free 960 // the same region again. If the current range is entirely within that 961 // region, skip it. 962 if (start_region == prev_last_region) { 963 start_address = start_region->end(); 964 if (start_address > last_address) { 965 continue; 966 } 967 start_region = _hrm.addr_to_region(start_address); 968 } 969 prev_last_region = last_region; 970 971 // After verifying that each region was marked as an archive region by 972 // alloc_archive_regions, set it free and empty and uncommit it. 973 HeapRegion* curr_region = start_region; 974 while (curr_region != NULL) { 975 guarantee(curr_region->is_archive(), 976 "Expected archive region at index %u", curr_region->hrm_index()); 977 uint curr_index = curr_region->hrm_index(); 978 _old_set.remove(curr_region); 979 curr_region->set_free(); 980 curr_region->set_top(curr_region->bottom()); 981 if (curr_region != last_region) { 982 curr_region = _hrm.next_region_in_heap(curr_region); 983 } else { 984 curr_region = NULL; 985 } 986 _hrm.shrink_at(curr_index, 1); 987 uncommitted_regions++; 988 } 989 990 // Notify mark-sweep that this is no longer an archive range. 991 G1MarkSweep::set_range_archive(ranges[i], false); 992 } 993 994 if (uncommitted_regions != 0) { 995 ergo_verbose1(ErgoHeapSizing, 996 "attempt heap shrinking", 997 ergo_format_reason("uncommitted archive regions") 998 ergo_format_byte("total size"), 999 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 1000 } 1001 decrease_used(size_used); 1002 } 1003 1004 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 1005 uint* gc_count_before_ret, 1006 uint* gclocker_retry_count_ret) { 1007 // The structure of this method has a lot of similarities to 1008 // attempt_allocation_slow(). The reason these two were not merged 1009 // into a single one is that such a method would require several "if 1010 // allocation is not humongous do this, otherwise do that" 1011 // conditional paths which would obscure its flow. In fact, an early 1012 // version of this code did use a unified method which was harder to 1013 // follow and, as a result, it had subtle bugs that were hard to 1014 // track down. So keeping these two methods separate allows each to 1015 // be more readable. It will be good to keep these two in sync as 1016 // much as possible. 1017 1018 assert_heap_not_locked_and_not_at_safepoint(); 1019 assert(is_humongous(word_size), "attempt_allocation_humongous() " 1020 "should only be called for humongous allocations"); 1021 1022 // Humongous objects can exhaust the heap quickly, so we should check if we 1023 // need to start a marking cycle at each humongous object allocation. We do 1024 // the check before we do the actual allocation. The reason for doing it 1025 // before the allocation is that we avoid having to keep track of the newly 1026 // allocated memory while we do a GC. 1027 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1028 word_size)) { 1029 collect(GCCause::_g1_humongous_allocation); 1030 } 1031 1032 // We will loop until a) we manage to successfully perform the 1033 // allocation or b) we successfully schedule a collection which 1034 // fails to perform the allocation. b) is the only case when we'll 1035 // return NULL. 1036 HeapWord* result = NULL; 1037 for (int try_count = 1; /* we'll return */; try_count += 1) { 1038 bool should_try_gc; 1039 uint gc_count_before; 1040 1041 { 1042 MutexLockerEx x(Heap_lock); 1043 1044 // Given that humongous objects are not allocated in young 1045 // regions, we'll first try to do the allocation without doing a 1046 // collection hoping that there's enough space in the heap. 1047 result = humongous_obj_allocate(word_size, AllocationContext::current()); 1048 if (result != NULL) { 1049 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 1050 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 1051 return result; 1052 } 1053 1054 if (GC_locker::is_active_and_needs_gc()) { 1055 should_try_gc = false; 1056 } else { 1057 // The GCLocker may not be active but the GCLocker initiated 1058 // GC may not yet have been performed (GCLocker::needs_gc() 1059 // returns true). In this case we do not try this GC and 1060 // wait until the GCLocker initiated GC is performed, and 1061 // then retry the allocation. 1062 if (GC_locker::needs_gc()) { 1063 should_try_gc = false; 1064 } else { 1065 // Read the GC count while still holding the Heap_lock. 1066 gc_count_before = total_collections(); 1067 should_try_gc = true; 1068 } 1069 } 1070 } 1071 1072 if (should_try_gc) { 1073 // If we failed to allocate the humongous object, we should try to 1074 // do a collection pause (if we're allowed) in case it reclaims 1075 // enough space for the allocation to succeed after the pause. 1076 1077 bool succeeded; 1078 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1079 GCCause::_g1_humongous_allocation); 1080 if (result != NULL) { 1081 assert(succeeded, "only way to get back a non-NULL result"); 1082 return result; 1083 } 1084 1085 if (succeeded) { 1086 // If we get here we successfully scheduled a collection which 1087 // failed to allocate. No point in trying to allocate 1088 // further. We'll just return NULL. 1089 MutexLockerEx x(Heap_lock); 1090 *gc_count_before_ret = total_collections(); 1091 return NULL; 1092 } 1093 } else { 1094 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1095 MutexLockerEx x(Heap_lock); 1096 *gc_count_before_ret = total_collections(); 1097 return NULL; 1098 } 1099 // The GCLocker is either active or the GCLocker initiated 1100 // GC has not yet been performed. Stall until it is and 1101 // then retry the allocation. 1102 GC_locker::stall_until_clear(); 1103 (*gclocker_retry_count_ret) += 1; 1104 } 1105 1106 // We can reach here if we were unsuccessful in scheduling a 1107 // collection (because another thread beat us to it) or if we were 1108 // stalled due to the GC locker. In either can we should retry the 1109 // allocation attempt in case another thread successfully 1110 // performed a collection and reclaimed enough space. Give a 1111 // warning if we seem to be looping forever. 1112 1113 if ((QueuedAllocationWarningCount > 0) && 1114 (try_count % QueuedAllocationWarningCount == 0)) { 1115 warning("G1CollectedHeap::attempt_allocation_humongous() " 1116 "retries %d times", try_count); 1117 } 1118 } 1119 1120 ShouldNotReachHere(); 1121 return NULL; 1122 } 1123 1124 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1125 AllocationContext_t context, 1126 bool expect_null_mutator_alloc_region) { 1127 assert_at_safepoint(true /* should_be_vm_thread */); 1128 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region, 1129 "the current alloc region was unexpectedly found to be non-NULL"); 1130 1131 if (!is_humongous(word_size)) { 1132 return _allocator->attempt_allocation_locked(word_size, context); 1133 } else { 1134 HeapWord* result = humongous_obj_allocate(word_size, context); 1135 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1136 collector_state()->set_initiate_conc_mark_if_possible(true); 1137 } 1138 return result; 1139 } 1140 1141 ShouldNotReachHere(); 1142 } 1143 1144 class PostMCRemSetClearClosure: public HeapRegionClosure { 1145 G1CollectedHeap* _g1h; 1146 ModRefBarrierSet* _mr_bs; 1147 public: 1148 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1149 _g1h(g1h), _mr_bs(mr_bs) {} 1150 1151 bool doHeapRegion(HeapRegion* r) { 1152 HeapRegionRemSet* hrrs = r->rem_set(); 1153 1154 _g1h->reset_gc_time_stamps(r); 1155 1156 if (r->is_continues_humongous()) { 1157 // We'll assert that the strong code root list and RSet is empty 1158 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1159 assert(hrrs->occupied() == 0, "RSet should be empty"); 1160 } else { 1161 hrrs->clear(); 1162 } 1163 // You might think here that we could clear just the cards 1164 // corresponding to the used region. But no: if we leave a dirty card 1165 // in a region we might allocate into, then it would prevent that card 1166 // from being enqueued, and cause it to be missed. 1167 // Re: the performance cost: we shouldn't be doing full GC anyway! 1168 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1169 1170 return false; 1171 } 1172 }; 1173 1174 void G1CollectedHeap::clear_rsets_post_compaction() { 1175 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1176 heap_region_iterate(&rs_clear); 1177 } 1178 1179 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1180 G1CollectedHeap* _g1h; 1181 UpdateRSOopClosure _cl; 1182 public: 1183 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) : 1184 _cl(g1->g1_rem_set(), worker_i), 1185 _g1h(g1) 1186 { } 1187 1188 bool doHeapRegion(HeapRegion* r) { 1189 if (!r->is_continues_humongous()) { 1190 _cl.set_from(r); 1191 r->oop_iterate(&_cl); 1192 } 1193 return false; 1194 } 1195 }; 1196 1197 class ParRebuildRSTask: public AbstractGangTask { 1198 G1CollectedHeap* _g1; 1199 HeapRegionClaimer _hrclaimer; 1200 1201 public: 1202 ParRebuildRSTask(G1CollectedHeap* g1) : 1203 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {} 1204 1205 void work(uint worker_id) { 1206 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1207 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer); 1208 } 1209 }; 1210 1211 class PostCompactionPrinterClosure: public HeapRegionClosure { 1212 private: 1213 G1HRPrinter* _hr_printer; 1214 public: 1215 bool doHeapRegion(HeapRegion* hr) { 1216 assert(!hr->is_young(), "not expecting to find young regions"); 1217 if (hr->is_free()) { 1218 // We only generate output for non-empty regions. 1219 } else if (hr->is_starts_humongous()) { 1220 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1221 } else if (hr->is_continues_humongous()) { 1222 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1223 } else if (hr->is_archive()) { 1224 _hr_printer->post_compaction(hr, G1HRPrinter::Archive); 1225 } else if (hr->is_old()) { 1226 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1227 } else { 1228 ShouldNotReachHere(); 1229 } 1230 return false; 1231 } 1232 1233 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1234 : _hr_printer(hr_printer) { } 1235 }; 1236 1237 void G1CollectedHeap::print_hrm_post_compaction() { 1238 PostCompactionPrinterClosure cl(hr_printer()); 1239 heap_region_iterate(&cl); 1240 } 1241 1242 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1243 bool clear_all_soft_refs) { 1244 assert_at_safepoint(true /* should_be_vm_thread */); 1245 1246 if (GC_locker::check_active_before_gc()) { 1247 return false; 1248 } 1249 1250 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1251 gc_timer->register_gc_start(); 1252 1253 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1254 GCIdMark gc_id_mark; 1255 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1256 1257 SvcGCMarker sgcm(SvcGCMarker::FULL); 1258 ResourceMark rm; 1259 1260 G1Log::update_level(); 1261 print_heap_before_gc(); 1262 trace_heap_before_gc(gc_tracer); 1263 1264 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1265 1266 verify_region_sets_optional(); 1267 1268 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1269 collector_policy()->should_clear_all_soft_refs(); 1270 1271 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1272 1273 { 1274 IsGCActiveMark x; 1275 1276 // Timing 1277 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1278 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1279 1280 { 1281 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL); 1282 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1283 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1284 1285 g1_policy()->record_full_collection_start(); 1286 1287 // Note: When we have a more flexible GC logging framework that 1288 // allows us to add optional attributes to a GC log record we 1289 // could consider timing and reporting how long we wait in the 1290 // following two methods. 1291 wait_while_free_regions_coming(); 1292 // If we start the compaction before the CM threads finish 1293 // scanning the root regions we might trip them over as we'll 1294 // be moving objects / updating references. So let's wait until 1295 // they are done. By telling them to abort, they should complete 1296 // early. 1297 _cm->root_regions()->abort(); 1298 _cm->root_regions()->wait_until_scan_finished(); 1299 append_secondary_free_list_if_not_empty_with_lock(); 1300 1301 gc_prologue(true); 1302 increment_total_collections(true /* full gc */); 1303 increment_old_marking_cycles_started(); 1304 1305 assert(used() == recalculate_used(), "Should be equal"); 1306 1307 verify_before_gc(); 1308 1309 check_bitmaps("Full GC Start"); 1310 pre_full_gc_dump(gc_timer); 1311 1312 #if defined(COMPILER2) || INCLUDE_JVMCI 1313 DerivedPointerTable::clear(); 1314 #endif 1315 1316 // Disable discovery and empty the discovered lists 1317 // for the CM ref processor. 1318 ref_processor_cm()->disable_discovery(); 1319 ref_processor_cm()->abandon_partial_discovery(); 1320 ref_processor_cm()->verify_no_references_recorded(); 1321 1322 // Abandon current iterations of concurrent marking and concurrent 1323 // refinement, if any are in progress. We have to do this before 1324 // wait_until_scan_finished() below. 1325 concurrent_mark()->abort(); 1326 1327 // Make sure we'll choose a new allocation region afterwards. 1328 _allocator->release_mutator_alloc_region(); 1329 _allocator->abandon_gc_alloc_regions(); 1330 g1_rem_set()->cleanupHRRS(); 1331 1332 // We should call this after we retire any currently active alloc 1333 // regions so that all the ALLOC / RETIRE events are generated 1334 // before the start GC event. 1335 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1336 1337 // We may have added regions to the current incremental collection 1338 // set between the last GC or pause and now. We need to clear the 1339 // incremental collection set and then start rebuilding it afresh 1340 // after this full GC. 1341 abandon_collection_set(g1_policy()->inc_cset_head()); 1342 g1_policy()->clear_incremental_cset(); 1343 g1_policy()->stop_incremental_cset_building(); 1344 1345 tear_down_region_sets(false /* free_list_only */); 1346 collector_state()->set_gcs_are_young(true); 1347 1348 // See the comments in g1CollectedHeap.hpp and 1349 // G1CollectedHeap::ref_processing_init() about 1350 // how reference processing currently works in G1. 1351 1352 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1353 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1354 1355 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1356 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1357 1358 ref_processor_stw()->enable_discovery(); 1359 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1360 1361 // Do collection work 1362 { 1363 HandleMark hm; // Discard invalid handles created during gc 1364 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1365 } 1366 1367 assert(num_free_regions() == 0, "we should not have added any free regions"); 1368 rebuild_region_sets(false /* free_list_only */); 1369 1370 // Enqueue any discovered reference objects that have 1371 // not been removed from the discovered lists. 1372 ref_processor_stw()->enqueue_discovered_references(); 1373 1374 #if defined(COMPILER2) || INCLUDE_JVMCI 1375 DerivedPointerTable::update_pointers(); 1376 #endif 1377 1378 MemoryService::track_memory_usage(); 1379 1380 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1381 ref_processor_stw()->verify_no_references_recorded(); 1382 1383 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1384 ClassLoaderDataGraph::purge(); 1385 MetaspaceAux::verify_metrics(); 1386 1387 // Note: since we've just done a full GC, concurrent 1388 // marking is no longer active. Therefore we need not 1389 // re-enable reference discovery for the CM ref processor. 1390 // That will be done at the start of the next marking cycle. 1391 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1392 ref_processor_cm()->verify_no_references_recorded(); 1393 1394 reset_gc_time_stamp(); 1395 // Since everything potentially moved, we will clear all remembered 1396 // sets, and clear all cards. Later we will rebuild remembered 1397 // sets. We will also reset the GC time stamps of the regions. 1398 clear_rsets_post_compaction(); 1399 check_gc_time_stamps(); 1400 1401 resize_if_necessary_after_full_collection(); 1402 1403 if (_hr_printer.is_active()) { 1404 // We should do this after we potentially resize the heap so 1405 // that all the COMMIT / UNCOMMIT events are generated before 1406 // the end GC event. 1407 1408 print_hrm_post_compaction(); 1409 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1410 } 1411 1412 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1413 if (hot_card_cache->use_cache()) { 1414 hot_card_cache->reset_card_counts(); 1415 hot_card_cache->reset_hot_cache(); 1416 } 1417 1418 // Rebuild remembered sets of all regions. 1419 uint n_workers = 1420 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1421 workers()->active_workers(), 1422 Threads::number_of_non_daemon_threads()); 1423 workers()->set_active_workers(n_workers); 1424 1425 ParRebuildRSTask rebuild_rs_task(this); 1426 workers()->run_task(&rebuild_rs_task); 1427 1428 // Rebuild the strong code root lists for each region 1429 rebuild_strong_code_roots(); 1430 1431 if (true) { // FIXME 1432 MetaspaceGC::compute_new_size(); 1433 } 1434 1435 #ifdef TRACESPINNING 1436 ParallelTaskTerminator::print_termination_counts(); 1437 #endif 1438 1439 // Discard all rset updates 1440 JavaThread::dirty_card_queue_set().abandon_logs(); 1441 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1442 1443 _young_list->reset_sampled_info(); 1444 // At this point there should be no regions in the 1445 // entire heap tagged as young. 1446 assert(check_young_list_empty(true /* check_heap */), 1447 "young list should be empty at this point"); 1448 1449 // Update the number of full collections that have been completed. 1450 increment_old_marking_cycles_completed(false /* concurrent */); 1451 1452 _hrm.verify_optional(); 1453 verify_region_sets_optional(); 1454 1455 verify_after_gc(); 1456 1457 // Clear the previous marking bitmap, if needed for bitmap verification. 1458 // Note we cannot do this when we clear the next marking bitmap in 1459 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1460 // objects marked during a full GC against the previous bitmap. 1461 // But we need to clear it before calling check_bitmaps below since 1462 // the full GC has compacted objects and updated TAMS but not updated 1463 // the prev bitmap. 1464 if (G1VerifyBitmaps) { 1465 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1466 } 1467 check_bitmaps("Full GC End"); 1468 1469 // Start a new incremental collection set for the next pause 1470 assert(g1_policy()->collection_set() == NULL, "must be"); 1471 g1_policy()->start_incremental_cset_building(); 1472 1473 clear_cset_fast_test(); 1474 1475 _allocator->init_mutator_alloc_region(); 1476 1477 g1_policy()->record_full_collection_end(); 1478 1479 if (G1Log::fine()) { 1480 g1_policy()->print_heap_transition(); 1481 } 1482 1483 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1484 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1485 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1486 // before any GC notifications are raised. 1487 g1mm()->update_sizes(); 1488 1489 gc_epilogue(true); 1490 } 1491 1492 if (G1Log::finer()) { 1493 g1_policy()->print_detailed_heap_transition(true /* full */); 1494 } 1495 1496 print_heap_after_gc(); 1497 trace_heap_after_gc(gc_tracer); 1498 1499 post_full_gc_dump(gc_timer); 1500 1501 gc_timer->register_gc_end(); 1502 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1503 } 1504 1505 return true; 1506 } 1507 1508 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1509 // Currently, there is no facility in the do_full_collection(bool) API to notify 1510 // the caller that the collection did not succeed (e.g., because it was locked 1511 // out by the GC locker). So, right now, we'll ignore the return value. 1512 bool dummy = do_full_collection(true, /* explicit_gc */ 1513 clear_all_soft_refs); 1514 } 1515 1516 void G1CollectedHeap::resize_if_necessary_after_full_collection() { 1517 // Include bytes that will be pre-allocated to support collections, as "used". 1518 const size_t used_after_gc = used(); 1519 const size_t capacity_after_gc = capacity(); 1520 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1521 1522 // This is enforced in arguments.cpp. 1523 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1524 "otherwise the code below doesn't make sense"); 1525 1526 // We don't have floating point command-line arguments 1527 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1528 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1529 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1530 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1531 1532 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1533 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1534 1535 // We have to be careful here as these two calculations can overflow 1536 // 32-bit size_t's. 1537 double used_after_gc_d = (double) used_after_gc; 1538 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1539 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1540 1541 // Let's make sure that they are both under the max heap size, which 1542 // by default will make them fit into a size_t. 1543 double desired_capacity_upper_bound = (double) max_heap_size; 1544 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1545 desired_capacity_upper_bound); 1546 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1547 desired_capacity_upper_bound); 1548 1549 // We can now safely turn them into size_t's. 1550 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1551 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1552 1553 // This assert only makes sense here, before we adjust them 1554 // with respect to the min and max heap size. 1555 assert(minimum_desired_capacity <= maximum_desired_capacity, 1556 "minimum_desired_capacity = " SIZE_FORMAT ", " 1557 "maximum_desired_capacity = " SIZE_FORMAT, 1558 minimum_desired_capacity, maximum_desired_capacity); 1559 1560 // Should not be greater than the heap max size. No need to adjust 1561 // it with respect to the heap min size as it's a lower bound (i.e., 1562 // we'll try to make the capacity larger than it, not smaller). 1563 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1564 // Should not be less than the heap min size. No need to adjust it 1565 // with respect to the heap max size as it's an upper bound (i.e., 1566 // we'll try to make the capacity smaller than it, not greater). 1567 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1568 1569 if (capacity_after_gc < minimum_desired_capacity) { 1570 // Don't expand unless it's significant 1571 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1572 ergo_verbose4(ErgoHeapSizing, 1573 "attempt heap expansion", 1574 ergo_format_reason("capacity lower than " 1575 "min desired capacity after Full GC") 1576 ergo_format_byte("capacity") 1577 ergo_format_byte("occupancy") 1578 ergo_format_byte_perc("min desired capacity"), 1579 capacity_after_gc, used_after_gc, 1580 minimum_desired_capacity, (double) MinHeapFreeRatio); 1581 expand(expand_bytes); 1582 1583 // No expansion, now see if we want to shrink 1584 } else if (capacity_after_gc > maximum_desired_capacity) { 1585 // Capacity too large, compute shrinking size 1586 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1587 ergo_verbose4(ErgoHeapSizing, 1588 "attempt heap shrinking", 1589 ergo_format_reason("capacity higher than " 1590 "max desired capacity after Full GC") 1591 ergo_format_byte("capacity") 1592 ergo_format_byte("occupancy") 1593 ergo_format_byte_perc("max desired capacity"), 1594 capacity_after_gc, used_after_gc, 1595 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1596 shrink(shrink_bytes); 1597 } 1598 } 1599 1600 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1601 AllocationContext_t context, 1602 bool do_gc, 1603 bool clear_all_soft_refs, 1604 bool expect_null_mutator_alloc_region, 1605 bool* gc_succeeded) { 1606 *gc_succeeded = true; 1607 // Let's attempt the allocation first. 1608 HeapWord* result = 1609 attempt_allocation_at_safepoint(word_size, 1610 context, 1611 expect_null_mutator_alloc_region); 1612 if (result != NULL) { 1613 assert(*gc_succeeded, "sanity"); 1614 return result; 1615 } 1616 1617 // In a G1 heap, we're supposed to keep allocation from failing by 1618 // incremental pauses. Therefore, at least for now, we'll favor 1619 // expansion over collection. (This might change in the future if we can 1620 // do something smarter than full collection to satisfy a failed alloc.) 1621 result = expand_and_allocate(word_size, context); 1622 if (result != NULL) { 1623 assert(*gc_succeeded, "sanity"); 1624 return result; 1625 } 1626 1627 if (do_gc) { 1628 // Expansion didn't work, we'll try to do a Full GC. 1629 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1630 clear_all_soft_refs); 1631 } 1632 1633 return NULL; 1634 } 1635 1636 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1637 AllocationContext_t context, 1638 bool* succeeded) { 1639 assert_at_safepoint(true /* should_be_vm_thread */); 1640 1641 // Attempts to allocate followed by Full GC. 1642 HeapWord* result = 1643 satisfy_failed_allocation_helper(word_size, 1644 context, 1645 true, /* do_gc */ 1646 false, /* clear_all_soft_refs */ 1647 false, /* expect_null_mutator_alloc_region */ 1648 succeeded); 1649 1650 if (result != NULL || !*succeeded) { 1651 return result; 1652 } 1653 1654 // Attempts to allocate followed by Full GC that will collect all soft references. 1655 result = satisfy_failed_allocation_helper(word_size, 1656 context, 1657 true, /* do_gc */ 1658 true, /* clear_all_soft_refs */ 1659 true, /* expect_null_mutator_alloc_region */ 1660 succeeded); 1661 1662 if (result != NULL || !*succeeded) { 1663 return result; 1664 } 1665 1666 // Attempts to allocate, no GC 1667 result = satisfy_failed_allocation_helper(word_size, 1668 context, 1669 false, /* do_gc */ 1670 false, /* clear_all_soft_refs */ 1671 true, /* expect_null_mutator_alloc_region */ 1672 succeeded); 1673 1674 if (result != NULL) { 1675 assert(*succeeded, "sanity"); 1676 return result; 1677 } 1678 1679 assert(!collector_policy()->should_clear_all_soft_refs(), 1680 "Flag should have been handled and cleared prior to this point"); 1681 1682 // What else? We might try synchronous finalization later. If the total 1683 // space available is large enough for the allocation, then a more 1684 // complete compaction phase than we've tried so far might be 1685 // appropriate. 1686 assert(*succeeded, "sanity"); 1687 return NULL; 1688 } 1689 1690 // Attempting to expand the heap sufficiently 1691 // to support an allocation of the given "word_size". If 1692 // successful, perform the allocation and return the address of the 1693 // allocated block, or else "NULL". 1694 1695 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1696 assert_at_safepoint(true /* should_be_vm_thread */); 1697 1698 verify_region_sets_optional(); 1699 1700 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1701 ergo_verbose1(ErgoHeapSizing, 1702 "attempt heap expansion", 1703 ergo_format_reason("allocation request failed") 1704 ergo_format_byte("allocation request"), 1705 word_size * HeapWordSize); 1706 if (expand(expand_bytes)) { 1707 _hrm.verify_optional(); 1708 verify_region_sets_optional(); 1709 return attempt_allocation_at_safepoint(word_size, 1710 context, 1711 false /* expect_null_mutator_alloc_region */); 1712 } 1713 return NULL; 1714 } 1715 1716 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) { 1717 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1718 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1719 HeapRegion::GrainBytes); 1720 ergo_verbose2(ErgoHeapSizing, 1721 "expand the heap", 1722 ergo_format_byte("requested expansion amount") 1723 ergo_format_byte("attempted expansion amount"), 1724 expand_bytes, aligned_expand_bytes); 1725 1726 if (is_maximal_no_gc()) { 1727 ergo_verbose0(ErgoHeapSizing, 1728 "did not expand the heap", 1729 ergo_format_reason("heap already fully expanded")); 1730 return false; 1731 } 1732 1733 double expand_heap_start_time_sec = os::elapsedTime(); 1734 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1735 assert(regions_to_expand > 0, "Must expand by at least one region"); 1736 1737 uint expanded_by = _hrm.expand_by(regions_to_expand); 1738 if (expand_time_ms != NULL) { 1739 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1740 } 1741 1742 if (expanded_by > 0) { 1743 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1744 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1745 g1_policy()->record_new_heap_size(num_regions()); 1746 } else { 1747 ergo_verbose0(ErgoHeapSizing, 1748 "did not expand the heap", 1749 ergo_format_reason("heap expansion operation failed")); 1750 // The expansion of the virtual storage space was unsuccessful. 1751 // Let's see if it was because we ran out of swap. 1752 if (G1ExitOnExpansionFailure && 1753 _hrm.available() >= regions_to_expand) { 1754 // We had head room... 1755 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1756 } 1757 } 1758 return regions_to_expand > 0; 1759 } 1760 1761 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1762 size_t aligned_shrink_bytes = 1763 ReservedSpace::page_align_size_down(shrink_bytes); 1764 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1765 HeapRegion::GrainBytes); 1766 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1767 1768 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1769 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1770 1771 ergo_verbose3(ErgoHeapSizing, 1772 "shrink the heap", 1773 ergo_format_byte("requested shrinking amount") 1774 ergo_format_byte("aligned shrinking amount") 1775 ergo_format_byte("attempted shrinking amount"), 1776 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1777 if (num_regions_removed > 0) { 1778 g1_policy()->record_new_heap_size(num_regions()); 1779 } else { 1780 ergo_verbose0(ErgoHeapSizing, 1781 "did not shrink the heap", 1782 ergo_format_reason("heap shrinking operation failed")); 1783 } 1784 } 1785 1786 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1787 verify_region_sets_optional(); 1788 1789 // We should only reach here at the end of a Full GC which means we 1790 // should not not be holding to any GC alloc regions. The method 1791 // below will make sure of that and do any remaining clean up. 1792 _allocator->abandon_gc_alloc_regions(); 1793 1794 // Instead of tearing down / rebuilding the free lists here, we 1795 // could instead use the remove_all_pending() method on free_list to 1796 // remove only the ones that we need to remove. 1797 tear_down_region_sets(true /* free_list_only */); 1798 shrink_helper(shrink_bytes); 1799 rebuild_region_sets(true /* free_list_only */); 1800 1801 _hrm.verify_optional(); 1802 verify_region_sets_optional(); 1803 } 1804 1805 // Public methods. 1806 1807 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1808 CollectedHeap(), 1809 _g1_policy(policy_), 1810 _dirty_card_queue_set(false), 1811 _is_alive_closure_cm(this), 1812 _is_alive_closure_stw(this), 1813 _ref_processor_cm(NULL), 1814 _ref_processor_stw(NULL), 1815 _bot_shared(NULL), 1816 _cg1r(NULL), 1817 _g1mm(NULL), 1818 _refine_cte_cl(NULL), 1819 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1820 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1821 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1822 _humongous_reclaim_candidates(), 1823 _has_humongous_reclaim_candidates(false), 1824 _archive_allocator(NULL), 1825 _free_regions_coming(false), 1826 _young_list(new YoungList(this)), 1827 _gc_time_stamp(0), 1828 _summary_bytes_used(0), 1829 _survivor_evac_stats(YoungPLABSize, PLABWeight), 1830 _old_evac_stats(OldPLABSize, PLABWeight), 1831 _expand_heap_after_alloc_failure(true), 1832 _old_marking_cycles_started(0), 1833 _old_marking_cycles_completed(0), 1834 _heap_summary_sent(false), 1835 _in_cset_fast_test(), 1836 _dirty_cards_region_list(NULL), 1837 _worker_cset_start_region(NULL), 1838 _worker_cset_start_region_time_stamp(NULL), 1839 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1840 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1841 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1842 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1843 1844 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1845 /* are_GC_task_threads */true, 1846 /* are_ConcurrentGC_threads */false); 1847 _workers->initialize_workers(); 1848 1849 _allocator = G1Allocator::create_allocator(this); 1850 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1851 1852 // Override the default _filler_array_max_size so that no humongous filler 1853 // objects are created. 1854 _filler_array_max_size = _humongous_object_threshold_in_words; 1855 1856 uint n_queues = ParallelGCThreads; 1857 _task_queues = new RefToScanQueueSet(n_queues); 1858 1859 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1860 assert(n_rem_sets > 0, "Invariant."); 1861 1862 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1863 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC); 1864 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1865 1866 for (uint i = 0; i < n_queues; i++) { 1867 RefToScanQueue* q = new RefToScanQueue(); 1868 q->initialize(); 1869 _task_queues->register_queue(i, q); 1870 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1871 } 1872 clear_cset_start_regions(); 1873 1874 // Initialize the G1EvacuationFailureALot counters and flags. 1875 NOT_PRODUCT(reset_evacuation_should_fail();) 1876 1877 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1878 } 1879 1880 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1881 size_t size, 1882 size_t translation_factor) { 1883 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1884 // Allocate a new reserved space, preferring to use large pages. 1885 ReservedSpace rs(size, preferred_page_size); 1886 G1RegionToSpaceMapper* result = 1887 G1RegionToSpaceMapper::create_mapper(rs, 1888 size, 1889 rs.alignment(), 1890 HeapRegion::GrainBytes, 1891 translation_factor, 1892 mtGC); 1893 if (TracePageSizes) { 1894 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT, 1895 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size); 1896 } 1897 return result; 1898 } 1899 1900 jint G1CollectedHeap::initialize() { 1901 CollectedHeap::pre_initialize(); 1902 os::enable_vtime(); 1903 1904 G1Log::init(); 1905 1906 // Necessary to satisfy locking discipline assertions. 1907 1908 MutexLocker x(Heap_lock); 1909 1910 // We have to initialize the printer before committing the heap, as 1911 // it will be used then. 1912 _hr_printer.set_active(G1PrintHeapRegions); 1913 1914 // While there are no constraints in the GC code that HeapWordSize 1915 // be any particular value, there are multiple other areas in the 1916 // system which believe this to be true (e.g. oop->object_size in some 1917 // cases incorrectly returns the size in wordSize units rather than 1918 // HeapWordSize). 1919 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1920 1921 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1922 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1923 size_t heap_alignment = collector_policy()->heap_alignment(); 1924 1925 // Ensure that the sizes are properly aligned. 1926 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1927 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1928 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1929 1930 _refine_cte_cl = new RefineCardTableEntryClosure(); 1931 1932 jint ecode = JNI_OK; 1933 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode); 1934 if (_cg1r == NULL) { 1935 return ecode; 1936 } 1937 1938 // Reserve the maximum. 1939 1940 // When compressed oops are enabled, the preferred heap base 1941 // is calculated by subtracting the requested size from the 1942 // 32Gb boundary and using the result as the base address for 1943 // heap reservation. If the requested size is not aligned to 1944 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1945 // into the ReservedHeapSpace constructor) then the actual 1946 // base of the reserved heap may end up differing from the 1947 // address that was requested (i.e. the preferred heap base). 1948 // If this happens then we could end up using a non-optimal 1949 // compressed oops mode. 1950 1951 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1952 heap_alignment); 1953 1954 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1955 1956 // Create the barrier set for the entire reserved region. 1957 G1SATBCardTableLoggingModRefBS* bs 1958 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 1959 bs->initialize(); 1960 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 1961 set_barrier_set(bs); 1962 1963 // Also create a G1 rem set. 1964 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 1965 1966 // Carve out the G1 part of the heap. 1967 1968 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1969 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 1970 G1RegionToSpaceMapper* heap_storage = 1971 G1RegionToSpaceMapper::create_mapper(g1_rs, 1972 g1_rs.size(), 1973 page_size, 1974 HeapRegion::GrainBytes, 1975 1, 1976 mtJavaHeap); 1977 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(), 1978 max_byte_size, page_size, 1979 heap_rs.base(), 1980 heap_rs.size()); 1981 heap_storage->set_mapping_changed_listener(&_listener); 1982 1983 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1984 G1RegionToSpaceMapper* bot_storage = 1985 create_aux_memory_mapper("Block offset table", 1986 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize), 1987 G1BlockOffsetSharedArray::heap_map_factor()); 1988 1989 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 1990 G1RegionToSpaceMapper* cardtable_storage = 1991 create_aux_memory_mapper("Card table", 1992 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize), 1993 G1SATBCardTableLoggingModRefBS::heap_map_factor()); 1994 1995 G1RegionToSpaceMapper* card_counts_storage = 1996 create_aux_memory_mapper("Card counts table", 1997 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1998 G1CardCounts::heap_map_factor()); 1999 2000 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); 2001 G1RegionToSpaceMapper* prev_bitmap_storage = 2002 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor()); 2003 G1RegionToSpaceMapper* next_bitmap_storage = 2004 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor()); 2005 2006 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 2007 g1_barrier_set()->initialize(cardtable_storage); 2008 // Do later initialization work for concurrent refinement. 2009 _cg1r->init(card_counts_storage); 2010 2011 // 6843694 - ensure that the maximum region index can fit 2012 // in the remembered set structures. 2013 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2014 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2015 2016 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2017 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2018 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2019 "too many cards per region"); 2020 2021 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 2022 2023 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage); 2024 2025 { 2026 HeapWord* start = _hrm.reserved().start(); 2027 HeapWord* end = _hrm.reserved().end(); 2028 size_t granularity = HeapRegion::GrainBytes; 2029 2030 _in_cset_fast_test.initialize(start, end, granularity); 2031 _humongous_reclaim_candidates.initialize(start, end, granularity); 2032 } 2033 2034 // Create the ConcurrentMark data structure and thread. 2035 // (Must do this late, so that "max_regions" is defined.) 2036 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 2037 if (_cm == NULL || !_cm->completed_initialization()) { 2038 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 2039 return JNI_ENOMEM; 2040 } 2041 _cmThread = _cm->cmThread(); 2042 2043 // Initialize the from_card cache structure of HeapRegionRemSet. 2044 HeapRegionRemSet::init_heap(max_regions()); 2045 2046 // Now expand into the initial heap size. 2047 if (!expand(init_byte_size)) { 2048 vm_shutdown_during_initialization("Failed to allocate initial heap."); 2049 return JNI_ENOMEM; 2050 } 2051 2052 // Perform any initialization actions delegated to the policy. 2053 g1_policy()->init(); 2054 2055 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2056 SATB_Q_FL_lock, 2057 G1SATBProcessCompletedThreshold, 2058 Shared_SATB_Q_lock); 2059 2060 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 2061 DirtyCardQ_CBL_mon, 2062 DirtyCardQ_FL_lock, 2063 concurrent_g1_refine()->yellow_zone(), 2064 concurrent_g1_refine()->red_zone(), 2065 Shared_DirtyCardQ_lock); 2066 2067 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 2068 DirtyCardQ_CBL_mon, 2069 DirtyCardQ_FL_lock, 2070 -1, // never trigger processing 2071 -1, // no limit on length 2072 Shared_DirtyCardQ_lock, 2073 &JavaThread::dirty_card_queue_set()); 2074 2075 // Here we allocate the dummy HeapRegion that is required by the 2076 // G1AllocRegion class. 2077 HeapRegion* dummy_region = _hrm.get_dummy_region(); 2078 2079 // We'll re-use the same region whether the alloc region will 2080 // require BOT updates or not and, if it doesn't, then a non-young 2081 // region will complain that it cannot support allocations without 2082 // BOT updates. So we'll tag the dummy region as eden to avoid that. 2083 dummy_region->set_eden(); 2084 // Make sure it's full. 2085 dummy_region->set_top(dummy_region->end()); 2086 G1AllocRegion::setup(this, dummy_region); 2087 2088 _allocator->init_mutator_alloc_region(); 2089 2090 // Do create of the monitoring and management support so that 2091 // values in the heap have been properly initialized. 2092 _g1mm = new G1MonitoringSupport(this); 2093 2094 G1StringDedup::initialize(); 2095 2096 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC); 2097 for (uint i = 0; i < ParallelGCThreads; i++) { 2098 new (&_preserved_objs[i]) OopAndMarkOopStack(); 2099 } 2100 2101 return JNI_OK; 2102 } 2103 2104 void G1CollectedHeap::stop() { 2105 // Stop all concurrent threads. We do this to make sure these threads 2106 // do not continue to execute and access resources (e.g. gclog_or_tty) 2107 // that are destroyed during shutdown. 2108 _cg1r->stop(); 2109 _cmThread->stop(); 2110 if (G1StringDedup::is_enabled()) { 2111 G1StringDedup::stop(); 2112 } 2113 } 2114 2115 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2116 return HeapRegion::max_region_size(); 2117 } 2118 2119 void G1CollectedHeap::post_initialize() { 2120 CollectedHeap::post_initialize(); 2121 ref_processing_init(); 2122 } 2123 2124 void G1CollectedHeap::ref_processing_init() { 2125 // Reference processing in G1 currently works as follows: 2126 // 2127 // * There are two reference processor instances. One is 2128 // used to record and process discovered references 2129 // during concurrent marking; the other is used to 2130 // record and process references during STW pauses 2131 // (both full and incremental). 2132 // * Both ref processors need to 'span' the entire heap as 2133 // the regions in the collection set may be dotted around. 2134 // 2135 // * For the concurrent marking ref processor: 2136 // * Reference discovery is enabled at initial marking. 2137 // * Reference discovery is disabled and the discovered 2138 // references processed etc during remarking. 2139 // * Reference discovery is MT (see below). 2140 // * Reference discovery requires a barrier (see below). 2141 // * Reference processing may or may not be MT 2142 // (depending on the value of ParallelRefProcEnabled 2143 // and ParallelGCThreads). 2144 // * A full GC disables reference discovery by the CM 2145 // ref processor and abandons any entries on it's 2146 // discovered lists. 2147 // 2148 // * For the STW processor: 2149 // * Non MT discovery is enabled at the start of a full GC. 2150 // * Processing and enqueueing during a full GC is non-MT. 2151 // * During a full GC, references are processed after marking. 2152 // 2153 // * Discovery (may or may not be MT) is enabled at the start 2154 // of an incremental evacuation pause. 2155 // * References are processed near the end of a STW evacuation pause. 2156 // * For both types of GC: 2157 // * Discovery is atomic - i.e. not concurrent. 2158 // * Reference discovery will not need a barrier. 2159 2160 MemRegion mr = reserved_region(); 2161 2162 // Concurrent Mark ref processor 2163 _ref_processor_cm = 2164 new ReferenceProcessor(mr, // span 2165 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2166 // mt processing 2167 ParallelGCThreads, 2168 // degree of mt processing 2169 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2170 // mt discovery 2171 MAX2(ParallelGCThreads, ConcGCThreads), 2172 // degree of mt discovery 2173 false, 2174 // Reference discovery is not atomic 2175 &_is_alive_closure_cm); 2176 // is alive closure 2177 // (for efficiency/performance) 2178 2179 // STW ref processor 2180 _ref_processor_stw = 2181 new ReferenceProcessor(mr, // span 2182 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2183 // mt processing 2184 ParallelGCThreads, 2185 // degree of mt processing 2186 (ParallelGCThreads > 1), 2187 // mt discovery 2188 ParallelGCThreads, 2189 // degree of mt discovery 2190 true, 2191 // Reference discovery is atomic 2192 &_is_alive_closure_stw); 2193 // is alive closure 2194 // (for efficiency/performance) 2195 } 2196 2197 CollectorPolicy* G1CollectedHeap::collector_policy() const { 2198 return g1_policy(); 2199 } 2200 2201 size_t G1CollectedHeap::capacity() const { 2202 return _hrm.length() * HeapRegion::GrainBytes; 2203 } 2204 2205 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2206 hr->reset_gc_time_stamp(); 2207 } 2208 2209 #ifndef PRODUCT 2210 2211 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2212 private: 2213 unsigned _gc_time_stamp; 2214 bool _failures; 2215 2216 public: 2217 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2218 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2219 2220 virtual bool doHeapRegion(HeapRegion* hr) { 2221 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2222 if (_gc_time_stamp != region_gc_time_stamp) { 2223 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, " 2224 "expected %d", HR_FORMAT_PARAMS(hr), 2225 region_gc_time_stamp, _gc_time_stamp); 2226 _failures = true; 2227 } 2228 return false; 2229 } 2230 2231 bool failures() { return _failures; } 2232 }; 2233 2234 void G1CollectedHeap::check_gc_time_stamps() { 2235 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2236 heap_region_iterate(&cl); 2237 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2238 } 2239 #endif // PRODUCT 2240 2241 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) { 2242 _cg1r->hot_card_cache()->drain(cl, worker_i); 2243 } 2244 2245 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) { 2246 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2247 size_t n_completed_buffers = 0; 2248 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2249 n_completed_buffers++; 2250 } 2251 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 2252 dcqs.clear_n_completed_buffers(); 2253 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2254 } 2255 2256 // Computes the sum of the storage used by the various regions. 2257 size_t G1CollectedHeap::used() const { 2258 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 2259 if (_archive_allocator != NULL) { 2260 result += _archive_allocator->used(); 2261 } 2262 return result; 2263 } 2264 2265 size_t G1CollectedHeap::used_unlocked() const { 2266 return _summary_bytes_used; 2267 } 2268 2269 class SumUsedClosure: public HeapRegionClosure { 2270 size_t _used; 2271 public: 2272 SumUsedClosure() : _used(0) {} 2273 bool doHeapRegion(HeapRegion* r) { 2274 _used += r->used(); 2275 return false; 2276 } 2277 size_t result() { return _used; } 2278 }; 2279 2280 size_t G1CollectedHeap::recalculate_used() const { 2281 double recalculate_used_start = os::elapsedTime(); 2282 2283 SumUsedClosure blk; 2284 heap_region_iterate(&blk); 2285 2286 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2287 return blk.result(); 2288 } 2289 2290 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2291 switch (cause) { 2292 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2293 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2294 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 2295 case GCCause::_g1_humongous_allocation: return true; 2296 case GCCause::_update_allocation_context_stats_inc: return true; 2297 case GCCause::_wb_conc_mark: return true; 2298 default: return false; 2299 } 2300 } 2301 2302 #ifndef PRODUCT 2303 void G1CollectedHeap::allocate_dummy_regions() { 2304 // Let's fill up most of the region 2305 size_t word_size = HeapRegion::GrainWords - 1024; 2306 // And as a result the region we'll allocate will be humongous. 2307 guarantee(is_humongous(word_size), "sanity"); 2308 2309 // _filler_array_max_size is set to humongous object threshold 2310 // but temporarily change it to use CollectedHeap::fill_with_object(). 2311 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2312 2313 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2314 // Let's use the existing mechanism for the allocation 2315 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2316 AllocationContext::system()); 2317 if (dummy_obj != NULL) { 2318 MemRegion mr(dummy_obj, word_size); 2319 CollectedHeap::fill_with_object(mr); 2320 } else { 2321 // If we can't allocate once, we probably cannot allocate 2322 // again. Let's get out of the loop. 2323 break; 2324 } 2325 } 2326 } 2327 #endif // !PRODUCT 2328 2329 void G1CollectedHeap::increment_old_marking_cycles_started() { 2330 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2331 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2332 "Wrong marking cycle count (started: %d, completed: %d)", 2333 _old_marking_cycles_started, _old_marking_cycles_completed); 2334 2335 _old_marking_cycles_started++; 2336 } 2337 2338 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2339 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2340 2341 // We assume that if concurrent == true, then the caller is a 2342 // concurrent thread that was joined the Suspendible Thread 2343 // Set. If there's ever a cheap way to check this, we should add an 2344 // assert here. 2345 2346 // Given that this method is called at the end of a Full GC or of a 2347 // concurrent cycle, and those can be nested (i.e., a Full GC can 2348 // interrupt a concurrent cycle), the number of full collections 2349 // completed should be either one (in the case where there was no 2350 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2351 // behind the number of full collections started. 2352 2353 // This is the case for the inner caller, i.e. a Full GC. 2354 assert(concurrent || 2355 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2356 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2357 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2358 "is inconsistent with _old_marking_cycles_completed = %u", 2359 _old_marking_cycles_started, _old_marking_cycles_completed); 2360 2361 // This is the case for the outer caller, i.e. the concurrent cycle. 2362 assert(!concurrent || 2363 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2364 "for outer caller (concurrent cycle): " 2365 "_old_marking_cycles_started = %u " 2366 "is inconsistent with _old_marking_cycles_completed = %u", 2367 _old_marking_cycles_started, _old_marking_cycles_completed); 2368 2369 _old_marking_cycles_completed += 1; 2370 2371 // We need to clear the "in_progress" flag in the CM thread before 2372 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2373 // is set) so that if a waiter requests another System.gc() it doesn't 2374 // incorrectly see that a marking cycle is still in progress. 2375 if (concurrent) { 2376 _cmThread->set_idle(); 2377 } 2378 2379 // This notify_all() will ensure that a thread that called 2380 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2381 // and it's waiting for a full GC to finish will be woken up. It is 2382 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2383 FullGCCount_lock->notify_all(); 2384 } 2385 2386 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2387 GCIdMarkAndRestore conc_gc_id_mark; 2388 collector_state()->set_concurrent_cycle_started(true); 2389 _gc_timer_cm->register_gc_start(start_time); 2390 2391 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2392 trace_heap_before_gc(_gc_tracer_cm); 2393 _cmThread->set_gc_id(GCId::current()); 2394 } 2395 2396 void G1CollectedHeap::register_concurrent_cycle_end() { 2397 if (collector_state()->concurrent_cycle_started()) { 2398 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id()); 2399 if (_cm->has_aborted()) { 2400 _gc_tracer_cm->report_concurrent_mode_failure(); 2401 } 2402 2403 _gc_timer_cm->register_gc_end(); 2404 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2405 2406 // Clear state variables to prepare for the next concurrent cycle. 2407 collector_state()->set_concurrent_cycle_started(false); 2408 _heap_summary_sent = false; 2409 } 2410 } 2411 2412 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2413 if (collector_state()->concurrent_cycle_started()) { 2414 // This function can be called when: 2415 // the cleanup pause is run 2416 // the concurrent cycle is aborted before the cleanup pause. 2417 // the concurrent cycle is aborted after the cleanup pause, 2418 // but before the concurrent cycle end has been registered. 2419 // Make sure that we only send the heap information once. 2420 if (!_heap_summary_sent) { 2421 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id()); 2422 trace_heap_after_gc(_gc_tracer_cm); 2423 _heap_summary_sent = true; 2424 } 2425 } 2426 } 2427 2428 void G1CollectedHeap::collect(GCCause::Cause cause) { 2429 assert_heap_not_locked(); 2430 2431 uint gc_count_before; 2432 uint old_marking_count_before; 2433 uint full_gc_count_before; 2434 bool retry_gc; 2435 2436 do { 2437 retry_gc = false; 2438 2439 { 2440 MutexLocker ml(Heap_lock); 2441 2442 // Read the GC count while holding the Heap_lock 2443 gc_count_before = total_collections(); 2444 full_gc_count_before = total_full_collections(); 2445 old_marking_count_before = _old_marking_cycles_started; 2446 } 2447 2448 if (should_do_concurrent_full_gc(cause)) { 2449 // Schedule an initial-mark evacuation pause that will start a 2450 // concurrent cycle. We're setting word_size to 0 which means that 2451 // we are not requesting a post-GC allocation. 2452 VM_G1IncCollectionPause op(gc_count_before, 2453 0, /* word_size */ 2454 true, /* should_initiate_conc_mark */ 2455 g1_policy()->max_pause_time_ms(), 2456 cause); 2457 op.set_allocation_context(AllocationContext::current()); 2458 2459 VMThread::execute(&op); 2460 if (!op.pause_succeeded()) { 2461 if (old_marking_count_before == _old_marking_cycles_started) { 2462 retry_gc = op.should_retry_gc(); 2463 } else { 2464 // A Full GC happened while we were trying to schedule the 2465 // initial-mark GC. No point in starting a new cycle given 2466 // that the whole heap was collected anyway. 2467 } 2468 2469 if (retry_gc) { 2470 if (GC_locker::is_active_and_needs_gc()) { 2471 GC_locker::stall_until_clear(); 2472 } 2473 } 2474 } 2475 } else { 2476 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2477 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2478 2479 // Schedule a standard evacuation pause. We're setting word_size 2480 // to 0 which means that we are not requesting a post-GC allocation. 2481 VM_G1IncCollectionPause op(gc_count_before, 2482 0, /* word_size */ 2483 false, /* should_initiate_conc_mark */ 2484 g1_policy()->max_pause_time_ms(), 2485 cause); 2486 VMThread::execute(&op); 2487 } else { 2488 // Schedule a Full GC. 2489 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2490 VMThread::execute(&op); 2491 } 2492 } 2493 } while (retry_gc); 2494 } 2495 2496 bool G1CollectedHeap::is_in(const void* p) const { 2497 if (_hrm.reserved().contains(p)) { 2498 // Given that we know that p is in the reserved space, 2499 // heap_region_containing() should successfully 2500 // return the containing region. 2501 HeapRegion* hr = heap_region_containing(p); 2502 return hr->is_in(p); 2503 } else { 2504 return false; 2505 } 2506 } 2507 2508 #ifdef ASSERT 2509 bool G1CollectedHeap::is_in_exact(const void* p) const { 2510 bool contains = reserved_region().contains(p); 2511 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2512 if (contains && available) { 2513 return true; 2514 } else { 2515 return false; 2516 } 2517 } 2518 #endif 2519 2520 bool G1CollectedHeap::obj_in_cs(oop obj) { 2521 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj); 2522 return r != NULL && r->in_collection_set(); 2523 } 2524 2525 // Iteration functions. 2526 2527 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2528 2529 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2530 ExtendedOopClosure* _cl; 2531 public: 2532 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2533 bool doHeapRegion(HeapRegion* r) { 2534 if (!r->is_continues_humongous()) { 2535 r->oop_iterate(_cl); 2536 } 2537 return false; 2538 } 2539 }; 2540 2541 // Iterates an ObjectClosure over all objects within a HeapRegion. 2542 2543 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2544 ObjectClosure* _cl; 2545 public: 2546 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2547 bool doHeapRegion(HeapRegion* r) { 2548 if (!r->is_continues_humongous()) { 2549 r->object_iterate(_cl); 2550 } 2551 return false; 2552 } 2553 }; 2554 2555 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2556 IterateObjectClosureRegionClosure blk(cl); 2557 heap_region_iterate(&blk); 2558 } 2559 2560 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2561 _hrm.iterate(cl); 2562 } 2563 2564 void 2565 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, 2566 uint worker_id, 2567 HeapRegionClaimer *hrclaimer, 2568 bool concurrent) const { 2569 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); 2570 } 2571 2572 // Clear the cached CSet starting regions and (more importantly) 2573 // the time stamps. Called when we reset the GC time stamp. 2574 void G1CollectedHeap::clear_cset_start_regions() { 2575 assert(_worker_cset_start_region != NULL, "sanity"); 2576 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2577 2578 for (uint i = 0; i < ParallelGCThreads; i++) { 2579 _worker_cset_start_region[i] = NULL; 2580 _worker_cset_start_region_time_stamp[i] = 0; 2581 } 2582 } 2583 2584 // Given the id of a worker, obtain or calculate a suitable 2585 // starting region for iterating over the current collection set. 2586 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2587 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2588 2589 HeapRegion* result = NULL; 2590 unsigned gc_time_stamp = get_gc_time_stamp(); 2591 2592 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2593 // Cached starting region for current worker was set 2594 // during the current pause - so it's valid. 2595 // Note: the cached starting heap region may be NULL 2596 // (when the collection set is empty). 2597 result = _worker_cset_start_region[worker_i]; 2598 assert(result == NULL || result->in_collection_set(), "sanity"); 2599 return result; 2600 } 2601 2602 // The cached entry was not valid so let's calculate 2603 // a suitable starting heap region for this worker. 2604 2605 // We want the parallel threads to start their collection 2606 // set iteration at different collection set regions to 2607 // avoid contention. 2608 // If we have: 2609 // n collection set regions 2610 // p threads 2611 // Then thread t will start at region floor ((t * n) / p) 2612 2613 result = g1_policy()->collection_set(); 2614 uint cs_size = g1_policy()->cset_region_length(); 2615 uint active_workers = workers()->active_workers(); 2616 2617 uint end_ind = (cs_size * worker_i) / active_workers; 2618 uint start_ind = 0; 2619 2620 if (worker_i > 0 && 2621 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2622 // Previous workers starting region is valid 2623 // so let's iterate from there 2624 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2625 result = _worker_cset_start_region[worker_i - 1]; 2626 } 2627 2628 for (uint i = start_ind; i < end_ind; i++) { 2629 result = result->next_in_collection_set(); 2630 } 2631 2632 // Note: the calculated starting heap region may be NULL 2633 // (when the collection set is empty). 2634 assert(result == NULL || result->in_collection_set(), "sanity"); 2635 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2636 "should be updated only once per pause"); 2637 _worker_cset_start_region[worker_i] = result; 2638 OrderAccess::storestore(); 2639 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2640 return result; 2641 } 2642 2643 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2644 HeapRegion* r = g1_policy()->collection_set(); 2645 while (r != NULL) { 2646 HeapRegion* next = r->next_in_collection_set(); 2647 if (cl->doHeapRegion(r)) { 2648 cl->incomplete(); 2649 return; 2650 } 2651 r = next; 2652 } 2653 } 2654 2655 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2656 HeapRegionClosure *cl) { 2657 if (r == NULL) { 2658 // The CSet is empty so there's nothing to do. 2659 return; 2660 } 2661 2662 assert(r->in_collection_set(), 2663 "Start region must be a member of the collection set."); 2664 HeapRegion* cur = r; 2665 while (cur != NULL) { 2666 HeapRegion* next = cur->next_in_collection_set(); 2667 if (cl->doHeapRegion(cur) && false) { 2668 cl->incomplete(); 2669 return; 2670 } 2671 cur = next; 2672 } 2673 cur = g1_policy()->collection_set(); 2674 while (cur != r) { 2675 HeapRegion* next = cur->next_in_collection_set(); 2676 if (cl->doHeapRegion(cur) && false) { 2677 cl->incomplete(); 2678 return; 2679 } 2680 cur = next; 2681 } 2682 } 2683 2684 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2685 HeapRegion* result = _hrm.next_region_in_heap(from); 2686 while (result != NULL && result->is_pinned()) { 2687 result = _hrm.next_region_in_heap(result); 2688 } 2689 return result; 2690 } 2691 2692 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2693 HeapRegion* hr = heap_region_containing(addr); 2694 return hr->block_start(addr); 2695 } 2696 2697 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2698 HeapRegion* hr = heap_region_containing(addr); 2699 return hr->block_size(addr); 2700 } 2701 2702 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2703 HeapRegion* hr = heap_region_containing(addr); 2704 return hr->block_is_obj(addr); 2705 } 2706 2707 bool G1CollectedHeap::supports_tlab_allocation() const { 2708 return true; 2709 } 2710 2711 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2712 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2713 } 2714 2715 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2716 return young_list()->eden_used_bytes(); 2717 } 2718 2719 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2720 // must be equal to the humongous object limit. 2721 size_t G1CollectedHeap::max_tlab_size() const { 2722 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment); 2723 } 2724 2725 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2726 AllocationContext_t context = AllocationContext::current(); 2727 return _allocator->unsafe_max_tlab_alloc(context); 2728 } 2729 2730 size_t G1CollectedHeap::max_capacity() const { 2731 return _hrm.reserved().byte_size(); 2732 } 2733 2734 jlong G1CollectedHeap::millis_since_last_gc() { 2735 // assert(false, "NYI"); 2736 return 0; 2737 } 2738 2739 void G1CollectedHeap::prepare_for_verify() { 2740 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2741 ensure_parsability(false); 2742 } 2743 g1_rem_set()->prepare_for_verify(); 2744 } 2745 2746 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 2747 VerifyOption vo) { 2748 switch (vo) { 2749 case VerifyOption_G1UsePrevMarking: 2750 return hr->obj_allocated_since_prev_marking(obj); 2751 case VerifyOption_G1UseNextMarking: 2752 return hr->obj_allocated_since_next_marking(obj); 2753 case VerifyOption_G1UseMarkWord: 2754 return false; 2755 default: 2756 ShouldNotReachHere(); 2757 } 2758 return false; // keep some compilers happy 2759 } 2760 2761 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 2762 switch (vo) { 2763 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 2764 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 2765 case VerifyOption_G1UseMarkWord: return NULL; 2766 default: ShouldNotReachHere(); 2767 } 2768 return NULL; // keep some compilers happy 2769 } 2770 2771 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 2772 switch (vo) { 2773 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 2774 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 2775 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 2776 default: ShouldNotReachHere(); 2777 } 2778 return false; // keep some compilers happy 2779 } 2780 2781 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 2782 switch (vo) { 2783 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 2784 case VerifyOption_G1UseNextMarking: return "NTAMS"; 2785 case VerifyOption_G1UseMarkWord: return "NONE"; 2786 default: ShouldNotReachHere(); 2787 } 2788 return NULL; // keep some compilers happy 2789 } 2790 2791 class VerifyRootsClosure: public OopClosure { 2792 private: 2793 G1CollectedHeap* _g1h; 2794 VerifyOption _vo; 2795 bool _failures; 2796 public: 2797 // _vo == UsePrevMarking -> use "prev" marking information, 2798 // _vo == UseNextMarking -> use "next" marking information, 2799 // _vo == UseMarkWord -> use mark word from object header. 2800 VerifyRootsClosure(VerifyOption vo) : 2801 _g1h(G1CollectedHeap::heap()), 2802 _vo(vo), 2803 _failures(false) { } 2804 2805 bool failures() { return _failures; } 2806 2807 template <class T> void do_oop_nv(T* p) { 2808 T heap_oop = oopDesc::load_heap_oop(p); 2809 if (!oopDesc::is_null(heap_oop)) { 2810 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2811 if (_g1h->is_obj_dead_cond(obj, _vo)) { 2812 gclog_or_tty->print_cr("Root location " PTR_FORMAT " " 2813 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj)); 2814 if (_vo == VerifyOption_G1UseMarkWord) { 2815 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark()); 2816 } 2817 obj->print_on(gclog_or_tty); 2818 _failures = true; 2819 } 2820 } 2821 } 2822 2823 void do_oop(oop* p) { do_oop_nv(p); } 2824 void do_oop(narrowOop* p) { do_oop_nv(p); } 2825 }; 2826 2827 class G1VerifyCodeRootOopClosure: public OopClosure { 2828 G1CollectedHeap* _g1h; 2829 OopClosure* _root_cl; 2830 nmethod* _nm; 2831 VerifyOption _vo; 2832 bool _failures; 2833 2834 template <class T> void do_oop_work(T* p) { 2835 // First verify that this root is live 2836 _root_cl->do_oop(p); 2837 2838 if (!G1VerifyHeapRegionCodeRoots) { 2839 // We're not verifying the code roots attached to heap region. 2840 return; 2841 } 2842 2843 // Don't check the code roots during marking verification in a full GC 2844 if (_vo == VerifyOption_G1UseMarkWord) { 2845 return; 2846 } 2847 2848 // Now verify that the current nmethod (which contains p) is 2849 // in the code root list of the heap region containing the 2850 // object referenced by p. 2851 2852 T heap_oop = oopDesc::load_heap_oop(p); 2853 if (!oopDesc::is_null(heap_oop)) { 2854 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2855 2856 // Now fetch the region containing the object 2857 HeapRegion* hr = _g1h->heap_region_containing(obj); 2858 HeapRegionRemSet* hrrs = hr->rem_set(); 2859 // Verify that the strong code root list for this region 2860 // contains the nmethod 2861 if (!hrrs->strong_code_roots_list_contains(_nm)) { 2862 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " " 2863 "from nmethod " PTR_FORMAT " not in strong " 2864 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")", 2865 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end())); 2866 _failures = true; 2867 } 2868 } 2869 } 2870 2871 public: 2872 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 2873 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 2874 2875 void do_oop(oop* p) { do_oop_work(p); } 2876 void do_oop(narrowOop* p) { do_oop_work(p); } 2877 2878 void set_nmethod(nmethod* nm) { _nm = nm; } 2879 bool failures() { return _failures; } 2880 }; 2881 2882 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 2883 G1VerifyCodeRootOopClosure* _oop_cl; 2884 2885 public: 2886 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 2887 _oop_cl(oop_cl) {} 2888 2889 void do_code_blob(CodeBlob* cb) { 2890 nmethod* nm = cb->as_nmethod_or_null(); 2891 if (nm != NULL) { 2892 _oop_cl->set_nmethod(nm); 2893 nm->oops_do(_oop_cl); 2894 } 2895 } 2896 }; 2897 2898 class YoungRefCounterClosure : public OopClosure { 2899 G1CollectedHeap* _g1h; 2900 int _count; 2901 public: 2902 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 2903 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 2904 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 2905 2906 int count() { return _count; } 2907 void reset_count() { _count = 0; }; 2908 }; 2909 2910 class VerifyKlassClosure: public KlassClosure { 2911 YoungRefCounterClosure _young_ref_counter_closure; 2912 OopClosure *_oop_closure; 2913 public: 2914 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 2915 void do_klass(Klass* k) { 2916 k->oops_do(_oop_closure); 2917 2918 _young_ref_counter_closure.reset_count(); 2919 k->oops_do(&_young_ref_counter_closure); 2920 if (_young_ref_counter_closure.count() > 0) { 2921 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)); 2922 } 2923 } 2924 }; 2925 2926 class VerifyLivenessOopClosure: public OopClosure { 2927 G1CollectedHeap* _g1h; 2928 VerifyOption _vo; 2929 public: 2930 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 2931 _g1h(g1h), _vo(vo) 2932 { } 2933 void do_oop(narrowOop *p) { do_oop_work(p); } 2934 void do_oop( oop *p) { do_oop_work(p); } 2935 2936 template <class T> void do_oop_work(T *p) { 2937 oop obj = oopDesc::load_decode_heap_oop(p); 2938 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 2939 "Dead object referenced by a not dead object"); 2940 } 2941 }; 2942 2943 class VerifyObjsInRegionClosure: public ObjectClosure { 2944 private: 2945 G1CollectedHeap* _g1h; 2946 size_t _live_bytes; 2947 HeapRegion *_hr; 2948 VerifyOption _vo; 2949 public: 2950 // _vo == UsePrevMarking -> use "prev" marking information, 2951 // _vo == UseNextMarking -> use "next" marking information, 2952 // _vo == UseMarkWord -> use mark word from object header. 2953 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 2954 : _live_bytes(0), _hr(hr), _vo(vo) { 2955 _g1h = G1CollectedHeap::heap(); 2956 } 2957 void do_object(oop o) { 2958 VerifyLivenessOopClosure isLive(_g1h, _vo); 2959 assert(o != NULL, "Huh?"); 2960 if (!_g1h->is_obj_dead_cond(o, _vo)) { 2961 // If the object is alive according to the mark word, 2962 // then verify that the marking information agrees. 2963 // Note we can't verify the contra-positive of the 2964 // above: if the object is dead (according to the mark 2965 // word), it may not be marked, or may have been marked 2966 // but has since became dead, or may have been allocated 2967 // since the last marking. 2968 if (_vo == VerifyOption_G1UseMarkWord) { 2969 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 2970 } 2971 2972 o->oop_iterate_no_header(&isLive); 2973 if (!_hr->obj_allocated_since_prev_marking(o)) { 2974 size_t obj_size = o->size(); // Make sure we don't overflow 2975 _live_bytes += (obj_size * HeapWordSize); 2976 } 2977 } 2978 } 2979 size_t live_bytes() { return _live_bytes; } 2980 }; 2981 2982 class VerifyArchiveOopClosure: public OopClosure { 2983 public: 2984 VerifyArchiveOopClosure(HeapRegion *hr) { } 2985 void do_oop(narrowOop *p) { do_oop_work(p); } 2986 void do_oop( oop *p) { do_oop_work(p); } 2987 2988 template <class T> void do_oop_work(T *p) { 2989 oop obj = oopDesc::load_decode_heap_oop(p); 2990 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj), 2991 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT, 2992 p2i(p), p2i(obj)); 2993 } 2994 }; 2995 2996 class VerifyArchiveRegionClosure: public ObjectClosure { 2997 public: 2998 VerifyArchiveRegionClosure(HeapRegion *hr) { } 2999 // Verify that all object pointers are to archive regions. 3000 void do_object(oop o) { 3001 VerifyArchiveOopClosure checkOop(NULL); 3002 assert(o != NULL, "Should not be here for NULL oops"); 3003 o->oop_iterate_no_header(&checkOop); 3004 } 3005 }; 3006 3007 class VerifyRegionClosure: public HeapRegionClosure { 3008 private: 3009 bool _par; 3010 VerifyOption _vo; 3011 bool _failures; 3012 public: 3013 // _vo == UsePrevMarking -> use "prev" marking information, 3014 // _vo == UseNextMarking -> use "next" marking information, 3015 // _vo == UseMarkWord -> use mark word from object header. 3016 VerifyRegionClosure(bool par, VerifyOption vo) 3017 : _par(par), 3018 _vo(vo), 3019 _failures(false) {} 3020 3021 bool failures() { 3022 return _failures; 3023 } 3024 3025 bool doHeapRegion(HeapRegion* r) { 3026 // For archive regions, verify there are no heap pointers to 3027 // non-pinned regions. For all others, verify liveness info. 3028 if (r->is_archive()) { 3029 VerifyArchiveRegionClosure verify_oop_pointers(r); 3030 r->object_iterate(&verify_oop_pointers); 3031 return true; 3032 } 3033 if (!r->is_continues_humongous()) { 3034 bool failures = false; 3035 r->verify(_vo, &failures); 3036 if (failures) { 3037 _failures = true; 3038 } else if (!r->is_starts_humongous()) { 3039 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3040 r->object_iterate(¬_dead_yet_cl); 3041 if (_vo != VerifyOption_G1UseNextMarking) { 3042 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3043 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] " 3044 "max_live_bytes " SIZE_FORMAT " " 3045 "< calculated " SIZE_FORMAT, 3046 p2i(r->bottom()), p2i(r->end()), 3047 r->max_live_bytes(), 3048 not_dead_yet_cl.live_bytes()); 3049 _failures = true; 3050 } 3051 } else { 3052 // When vo == UseNextMarking we cannot currently do a sanity 3053 // check on the live bytes as the calculation has not been 3054 // finalized yet. 3055 } 3056 } 3057 } 3058 return false; // stop the region iteration if we hit a failure 3059 } 3060 }; 3061 3062 // This is the task used for parallel verification of the heap regions 3063 3064 class G1ParVerifyTask: public AbstractGangTask { 3065 private: 3066 G1CollectedHeap* _g1h; 3067 VerifyOption _vo; 3068 bool _failures; 3069 HeapRegionClaimer _hrclaimer; 3070 3071 public: 3072 // _vo == UsePrevMarking -> use "prev" marking information, 3073 // _vo == UseNextMarking -> use "next" marking information, 3074 // _vo == UseMarkWord -> use mark word from object header. 3075 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3076 AbstractGangTask("Parallel verify task"), 3077 _g1h(g1h), 3078 _vo(vo), 3079 _failures(false), 3080 _hrclaimer(g1h->workers()->active_workers()) {} 3081 3082 bool failures() { 3083 return _failures; 3084 } 3085 3086 void work(uint worker_id) { 3087 HandleMark hm; 3088 VerifyRegionClosure blk(true, _vo); 3089 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer); 3090 if (blk.failures()) { 3091 _failures = true; 3092 } 3093 } 3094 }; 3095 3096 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3097 if (SafepointSynchronize::is_at_safepoint()) { 3098 assert(Thread::current()->is_VM_thread(), 3099 "Expected to be executed serially by the VM thread at this point"); 3100 3101 if (!silent) { gclog_or_tty->print("Roots "); } 3102 VerifyRootsClosure rootsCl(vo); 3103 VerifyKlassClosure klassCl(this, &rootsCl); 3104 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3105 3106 // We apply the relevant closures to all the oops in the 3107 // system dictionary, class loader data graph, the string table 3108 // and the nmethods in the code cache. 3109 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3110 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3111 3112 { 3113 G1RootProcessor root_processor(this, 1); 3114 root_processor.process_all_roots(&rootsCl, 3115 &cldCl, 3116 &blobsCl); 3117 } 3118 3119 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3120 3121 if (vo != VerifyOption_G1UseMarkWord) { 3122 // If we're verifying during a full GC then the region sets 3123 // will have been torn down at the start of the GC. Therefore 3124 // verifying the region sets will fail. So we only verify 3125 // the region sets when not in a full GC. 3126 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3127 verify_region_sets(); 3128 } 3129 3130 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3131 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3132 3133 G1ParVerifyTask task(this, vo); 3134 workers()->run_task(&task); 3135 if (task.failures()) { 3136 failures = true; 3137 } 3138 3139 } else { 3140 VerifyRegionClosure blk(false, vo); 3141 heap_region_iterate(&blk); 3142 if (blk.failures()) { 3143 failures = true; 3144 } 3145 } 3146 3147 if (G1StringDedup::is_enabled()) { 3148 if (!silent) gclog_or_tty->print("StrDedup "); 3149 G1StringDedup::verify(); 3150 } 3151 3152 if (failures) { 3153 gclog_or_tty->print_cr("Heap:"); 3154 // It helps to have the per-region information in the output to 3155 // help us track down what went wrong. This is why we call 3156 // print_extended_on() instead of print_on(). 3157 print_extended_on(gclog_or_tty); 3158 gclog_or_tty->cr(); 3159 gclog_or_tty->flush(); 3160 } 3161 guarantee(!failures, "there should not have been any failures"); 3162 } else { 3163 if (!silent) { 3164 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3165 if (G1StringDedup::is_enabled()) { 3166 gclog_or_tty->print(", StrDedup"); 3167 } 3168 gclog_or_tty->print(") "); 3169 } 3170 } 3171 } 3172 3173 void G1CollectedHeap::verify(bool silent) { 3174 verify(silent, VerifyOption_G1UsePrevMarking); 3175 } 3176 3177 double G1CollectedHeap::verify(bool guard, const char* msg) { 3178 double verify_time_ms = 0.0; 3179 3180 if (guard && total_collections() >= VerifyGCStartAt) { 3181 double verify_start = os::elapsedTime(); 3182 HandleMark hm; // Discard invalid handles created during verification 3183 prepare_for_verify(); 3184 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3185 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3186 } 3187 3188 return verify_time_ms; 3189 } 3190 3191 void G1CollectedHeap::verify_before_gc() { 3192 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3193 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3194 } 3195 3196 void G1CollectedHeap::verify_after_gc() { 3197 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3198 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3199 } 3200 3201 class PrintRegionClosure: public HeapRegionClosure { 3202 outputStream* _st; 3203 public: 3204 PrintRegionClosure(outputStream* st) : _st(st) {} 3205 bool doHeapRegion(HeapRegion* r) { 3206 r->print_on(_st); 3207 return false; 3208 } 3209 }; 3210 3211 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3212 const HeapRegion* hr, 3213 const VerifyOption vo) const { 3214 switch (vo) { 3215 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3216 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3217 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive(); 3218 default: ShouldNotReachHere(); 3219 } 3220 return false; // keep some compilers happy 3221 } 3222 3223 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3224 const VerifyOption vo) const { 3225 switch (vo) { 3226 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3227 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3228 case VerifyOption_G1UseMarkWord: { 3229 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj); 3230 return !obj->is_gc_marked() && !hr->is_archive(); 3231 } 3232 default: ShouldNotReachHere(); 3233 } 3234 return false; // keep some compilers happy 3235 } 3236 3237 void G1CollectedHeap::print_on(outputStream* st) const { 3238 st->print(" %-20s", "garbage-first heap"); 3239 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3240 capacity()/K, used_unlocked()/K); 3241 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")", 3242 p2i(_hrm.reserved().start()), 3243 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords), 3244 p2i(_hrm.reserved().end())); 3245 st->cr(); 3246 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3247 uint young_regions = _young_list->length(); 3248 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3249 (size_t) young_regions * HeapRegion::GrainBytes / K); 3250 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3251 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3252 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3253 st->cr(); 3254 MetaspaceAux::print_on(st); 3255 } 3256 3257 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3258 print_on(st); 3259 3260 // Print the per-region information. 3261 st->cr(); 3262 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, " 3263 "HS=humongous(starts), HC=humongous(continues), " 3264 "CS=collection set, F=free, A=archive, TS=gc time stamp, " 3265 "PTAMS=previous top-at-mark-start, " 3266 "NTAMS=next top-at-mark-start)"); 3267 PrintRegionClosure blk(st); 3268 heap_region_iterate(&blk); 3269 } 3270 3271 void G1CollectedHeap::print_on_error(outputStream* st) const { 3272 this->CollectedHeap::print_on_error(st); 3273 3274 if (_cm != NULL) { 3275 st->cr(); 3276 _cm->print_on_error(st); 3277 } 3278 } 3279 3280 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3281 workers()->print_worker_threads_on(st); 3282 _cmThread->print_on(st); 3283 st->cr(); 3284 _cm->print_worker_threads_on(st); 3285 _cg1r->print_worker_threads_on(st); 3286 if (G1StringDedup::is_enabled()) { 3287 G1StringDedup::print_worker_threads_on(st); 3288 } 3289 } 3290 3291 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3292 workers()->threads_do(tc); 3293 tc->do_thread(_cmThread); 3294 _cg1r->threads_do(tc); 3295 if (G1StringDedup::is_enabled()) { 3296 G1StringDedup::threads_do(tc); 3297 } 3298 } 3299 3300 void G1CollectedHeap::print_tracing_info() const { 3301 // We'll overload this to mean "trace GC pause statistics." 3302 if (TraceYoungGenTime || TraceOldGenTime) { 3303 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3304 // to that. 3305 g1_policy()->print_tracing_info(); 3306 } 3307 if (G1SummarizeRSetStats) { 3308 g1_rem_set()->print_summary_info(); 3309 } 3310 if (G1SummarizeConcMark) { 3311 concurrent_mark()->print_summary_info(); 3312 } 3313 g1_policy()->print_yg_surv_rate_info(); 3314 } 3315 3316 #ifndef PRODUCT 3317 // Helpful for debugging RSet issues. 3318 3319 class PrintRSetsClosure : public HeapRegionClosure { 3320 private: 3321 const char* _msg; 3322 size_t _occupied_sum; 3323 3324 public: 3325 bool doHeapRegion(HeapRegion* r) { 3326 HeapRegionRemSet* hrrs = r->rem_set(); 3327 size_t occupied = hrrs->occupied(); 3328 _occupied_sum += occupied; 3329 3330 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT, 3331 HR_FORMAT_PARAMS(r)); 3332 if (occupied == 0) { 3333 gclog_or_tty->print_cr(" RSet is empty"); 3334 } else { 3335 hrrs->print(); 3336 } 3337 gclog_or_tty->print_cr("----------"); 3338 return false; 3339 } 3340 3341 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3342 gclog_or_tty->cr(); 3343 gclog_or_tty->print_cr("========================================"); 3344 gclog_or_tty->print_cr("%s", msg); 3345 gclog_or_tty->cr(); 3346 } 3347 3348 ~PrintRSetsClosure() { 3349 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 3350 gclog_or_tty->print_cr("========================================"); 3351 gclog_or_tty->cr(); 3352 } 3353 }; 3354 3355 void G1CollectedHeap::print_cset_rsets() { 3356 PrintRSetsClosure cl("Printing CSet RSets"); 3357 collection_set_iterate(&cl); 3358 } 3359 3360 void G1CollectedHeap::print_all_rsets() { 3361 PrintRSetsClosure cl("Printing All RSets");; 3362 heap_region_iterate(&cl); 3363 } 3364 #endif // PRODUCT 3365 3366 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 3367 YoungList* young_list = heap()->young_list(); 3368 3369 size_t eden_used_bytes = young_list->eden_used_bytes(); 3370 size_t survivor_used_bytes = young_list->survivor_used_bytes(); 3371 3372 size_t eden_capacity_bytes = 3373 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 3374 3375 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 3376 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes); 3377 } 3378 3379 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 3380 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 3381 stats->unused(), stats->used(), stats->region_end_waste(), 3382 stats->regions_filled(), stats->direct_allocated(), 3383 stats->failure_used(), stats->failure_waste()); 3384 } 3385 3386 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 3387 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 3388 gc_tracer->report_gc_heap_summary(when, heap_summary); 3389 3390 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 3391 gc_tracer->report_metaspace_summary(when, metaspace_summary); 3392 } 3393 3394 3395 G1CollectedHeap* G1CollectedHeap::heap() { 3396 CollectedHeap* heap = Universe::heap(); 3397 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 3398 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); 3399 return (G1CollectedHeap*)heap; 3400 } 3401 3402 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3403 // always_do_update_barrier = false; 3404 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3405 // Fill TLAB's and such 3406 accumulate_statistics_all_tlabs(); 3407 ensure_parsability(true); 3408 3409 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3410 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3411 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3412 } 3413 } 3414 3415 void G1CollectedHeap::gc_epilogue(bool full) { 3416 3417 if (G1SummarizeRSetStats && 3418 (G1SummarizeRSetStatsPeriod > 0) && 3419 // we are at the end of the GC. Total collections has already been increased. 3420 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3421 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3422 } 3423 3424 // FIXME: what is this about? 3425 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3426 // is set. 3427 #if defined(COMPILER2) || INCLUDE_JVMCI 3428 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 3429 #endif 3430 // always_do_update_barrier = true; 3431 3432 resize_all_tlabs(); 3433 allocation_context_stats().update(full); 3434 3435 // We have just completed a GC. Update the soft reference 3436 // policy with the new heap occupancy 3437 Universe::update_heap_info_at_gc(); 3438 } 3439 3440 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3441 uint gc_count_before, 3442 bool* succeeded, 3443 GCCause::Cause gc_cause) { 3444 assert_heap_not_locked_and_not_at_safepoint(); 3445 g1_policy()->record_stop_world_start(); 3446 VM_G1IncCollectionPause op(gc_count_before, 3447 word_size, 3448 false, /* should_initiate_conc_mark */ 3449 g1_policy()->max_pause_time_ms(), 3450 gc_cause); 3451 3452 op.set_allocation_context(AllocationContext::current()); 3453 VMThread::execute(&op); 3454 3455 HeapWord* result = op.result(); 3456 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3457 assert(result == NULL || ret_succeeded, 3458 "the result should be NULL if the VM did not succeed"); 3459 *succeeded = ret_succeeded; 3460 3461 assert_heap_not_locked(); 3462 return result; 3463 } 3464 3465 void 3466 G1CollectedHeap::doConcurrentMark() { 3467 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3468 if (!_cmThread->in_progress()) { 3469 _cmThread->set_started(); 3470 CGC_lock->notify(); 3471 } 3472 } 3473 3474 size_t G1CollectedHeap::pending_card_num() { 3475 size_t extra_cards = 0; 3476 JavaThread *curr = Threads::first(); 3477 while (curr != NULL) { 3478 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3479 extra_cards += dcq.size(); 3480 curr = curr->next(); 3481 } 3482 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3483 size_t buffer_size = dcqs.buffer_size(); 3484 size_t buffer_num = dcqs.completed_buffers_num(); 3485 3486 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3487 // in bytes - not the number of 'entries'. We need to convert 3488 // into a number of cards. 3489 return (buffer_size * buffer_num + extra_cards) / oopSize; 3490 } 3491 3492 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3493 private: 3494 size_t _total_humongous; 3495 size_t _candidate_humongous; 3496 3497 DirtyCardQueue _dcq; 3498 3499 // We don't nominate objects with many remembered set entries, on 3500 // the assumption that such objects are likely still live. 3501 bool is_remset_small(HeapRegion* region) const { 3502 HeapRegionRemSet* const rset = region->rem_set(); 3503 return G1EagerReclaimHumongousObjectsWithStaleRefs 3504 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) 3505 : rset->is_empty(); 3506 } 3507 3508 bool is_typeArray_region(HeapRegion* region) const { 3509 return oop(region->bottom())->is_typeArray(); 3510 } 3511 3512 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { 3513 assert(region->is_starts_humongous(), "Must start a humongous object"); 3514 3515 // Candidate selection must satisfy the following constraints 3516 // while concurrent marking is in progress: 3517 // 3518 // * In order to maintain SATB invariants, an object must not be 3519 // reclaimed if it was allocated before the start of marking and 3520 // has not had its references scanned. Such an object must have 3521 // its references (including type metadata) scanned to ensure no 3522 // live objects are missed by the marking process. Objects 3523 // allocated after the start of concurrent marking don't need to 3524 // be scanned. 3525 // 3526 // * An object must not be reclaimed if it is on the concurrent 3527 // mark stack. Objects allocated after the start of concurrent 3528 // marking are never pushed on the mark stack. 3529 // 3530 // Nominating only objects allocated after the start of concurrent 3531 // marking is sufficient to meet both constraints. This may miss 3532 // some objects that satisfy the constraints, but the marking data 3533 // structures don't support efficiently performing the needed 3534 // additional tests or scrubbing of the mark stack. 3535 // 3536 // However, we presently only nominate is_typeArray() objects. 3537 // A humongous object containing references induces remembered 3538 // set entries on other regions. In order to reclaim such an 3539 // object, those remembered sets would need to be cleaned up. 3540 // 3541 // We also treat is_typeArray() objects specially, allowing them 3542 // to be reclaimed even if allocated before the start of 3543 // concurrent mark. For this we rely on mark stack insertion to 3544 // exclude is_typeArray() objects, preventing reclaiming an object 3545 // that is in the mark stack. We also rely on the metadata for 3546 // such objects to be built-in and so ensured to be kept live. 3547 // Frequent allocation and drop of large binary blobs is an 3548 // important use case for eager reclaim, and this special handling 3549 // may reduce needed headroom. 3550 3551 return is_typeArray_region(region) && is_remset_small(region); 3552 } 3553 3554 public: 3555 RegisterHumongousWithInCSetFastTestClosure() 3556 : _total_humongous(0), 3557 _candidate_humongous(0), 3558 _dcq(&JavaThread::dirty_card_queue_set()) { 3559 } 3560 3561 virtual bool doHeapRegion(HeapRegion* r) { 3562 if (!r->is_starts_humongous()) { 3563 return false; 3564 } 3565 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3566 3567 bool is_candidate = humongous_region_is_candidate(g1h, r); 3568 uint rindex = r->hrm_index(); 3569 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 3570 if (is_candidate) { 3571 _candidate_humongous++; 3572 g1h->register_humongous_region_with_cset(rindex); 3573 // Is_candidate already filters out humongous object with large remembered sets. 3574 // If we have a humongous object with a few remembered sets, we simply flush these 3575 // remembered set entries into the DCQS. That will result in automatic 3576 // re-evaluation of their remembered set entries during the following evacuation 3577 // phase. 3578 if (!r->rem_set()->is_empty()) { 3579 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 3580 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 3581 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 3582 HeapRegionRemSetIterator hrrs(r->rem_set()); 3583 size_t card_index; 3584 while (hrrs.has_next(card_index)) { 3585 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 3586 // The remembered set might contain references to already freed 3587 // regions. Filter out such entries to avoid failing card table 3588 // verification. 3589 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) { 3590 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 3591 *card_ptr = CardTableModRefBS::dirty_card_val(); 3592 _dcq.enqueue(card_ptr); 3593 } 3594 } 3595 } 3596 assert(hrrs.n_yielded() == r->rem_set()->occupied(), 3597 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", 3598 hrrs.n_yielded(), r->rem_set()->occupied()); 3599 r->rem_set()->clear_locked(); 3600 } 3601 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 3602 } 3603 _total_humongous++; 3604 3605 return false; 3606 } 3607 3608 size_t total_humongous() const { return _total_humongous; } 3609 size_t candidate_humongous() const { return _candidate_humongous; } 3610 3611 void flush_rem_set_entries() { _dcq.flush(); } 3612 }; 3613 3614 void G1CollectedHeap::register_humongous_regions_with_cset() { 3615 if (!G1EagerReclaimHumongousObjects) { 3616 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 3617 return; 3618 } 3619 double time = os::elapsed_counter(); 3620 3621 // Collect reclaim candidate information and register candidates with cset. 3622 RegisterHumongousWithInCSetFastTestClosure cl; 3623 heap_region_iterate(&cl); 3624 3625 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 3626 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 3627 cl.total_humongous(), 3628 cl.candidate_humongous()); 3629 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3630 3631 // Finally flush all remembered set entries to re-check into the global DCQS. 3632 cl.flush_rem_set_entries(); 3633 } 3634 3635 #ifdef ASSERT 3636 class VerifyCSetClosure: public HeapRegionClosure { 3637 public: 3638 bool doHeapRegion(HeapRegion* hr) { 3639 // Here we check that the CSet region's RSet is ready for parallel 3640 // iteration. The fields that we'll verify are only manipulated 3641 // when the region is part of a CSet and is collected. Afterwards, 3642 // we reset these fields when we clear the region's RSet (when the 3643 // region is freed) so they are ready when the region is 3644 // re-allocated. The only exception to this is if there's an 3645 // evacuation failure and instead of freeing the region we leave 3646 // it in the heap. In that case, we reset these fields during 3647 // evacuation failure handling. 3648 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3649 3650 // Here's a good place to add any other checks we'd like to 3651 // perform on CSet regions. 3652 return false; 3653 } 3654 }; 3655 #endif // ASSERT 3656 3657 uint G1CollectedHeap::num_task_queues() const { 3658 return _task_queues->size(); 3659 } 3660 3661 #if TASKQUEUE_STATS 3662 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3663 st->print_raw_cr("GC Task Stats"); 3664 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3665 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3666 } 3667 3668 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3669 print_taskqueue_stats_hdr(st); 3670 3671 TaskQueueStats totals; 3672 const uint n = num_task_queues(); 3673 for (uint i = 0; i < n; ++i) { 3674 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 3675 totals += task_queue(i)->stats; 3676 } 3677 st->print_raw("tot "); totals.print(st); st->cr(); 3678 3679 DEBUG_ONLY(totals.verify()); 3680 } 3681 3682 void G1CollectedHeap::reset_taskqueue_stats() { 3683 const uint n = num_task_queues(); 3684 for (uint i = 0; i < n; ++i) { 3685 task_queue(i)->stats.reset(); 3686 } 3687 } 3688 #endif // TASKQUEUE_STATS 3689 3690 void G1CollectedHeap::log_gc_header() { 3691 if (!G1Log::fine()) { 3692 return; 3693 } 3694 3695 gclog_or_tty->gclog_stamp(); 3696 3697 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3698 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)") 3699 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3700 3701 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3702 } 3703 3704 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3705 if (!G1Log::fine()) { 3706 return; 3707 } 3708 3709 if (G1Log::finer()) { 3710 if (evacuation_failed()) { 3711 gclog_or_tty->print(" (to-space exhausted)"); 3712 } 3713 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3714 g1_policy()->print_phases(pause_time_sec); 3715 g1_policy()->print_detailed_heap_transition(); 3716 } else { 3717 if (evacuation_failed()) { 3718 gclog_or_tty->print("--"); 3719 } 3720 g1_policy()->print_heap_transition(); 3721 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3722 } 3723 gclog_or_tty->flush(); 3724 } 3725 3726 void G1CollectedHeap::wait_for_root_region_scanning() { 3727 double scan_wait_start = os::elapsedTime(); 3728 // We have to wait until the CM threads finish scanning the 3729 // root regions as it's the only way to ensure that all the 3730 // objects on them have been correctly scanned before we start 3731 // moving them during the GC. 3732 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3733 double wait_time_ms = 0.0; 3734 if (waited) { 3735 double scan_wait_end = os::elapsedTime(); 3736 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3737 } 3738 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3739 } 3740 3741 bool 3742 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3743 assert_at_safepoint(true /* should_be_vm_thread */); 3744 guarantee(!is_gc_active(), "collection is not reentrant"); 3745 3746 if (GC_locker::check_active_before_gc()) { 3747 return false; 3748 } 3749 3750 _gc_timer_stw->register_gc_start(); 3751 3752 GCIdMark gc_id_mark; 3753 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3754 3755 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3756 ResourceMark rm; 3757 3758 wait_for_root_region_scanning(); 3759 3760 G1Log::update_level(); 3761 print_heap_before_gc(); 3762 trace_heap_before_gc(_gc_tracer_stw); 3763 3764 verify_region_sets_optional(); 3765 verify_dirty_young_regions(); 3766 3767 // This call will decide whether this pause is an initial-mark 3768 // pause. If it is, during_initial_mark_pause() will return true 3769 // for the duration of this pause. 3770 g1_policy()->decide_on_conc_mark_initiation(); 3771 3772 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3773 assert(!collector_state()->during_initial_mark_pause() || 3774 collector_state()->gcs_are_young(), "sanity"); 3775 3776 // We also do not allow mixed GCs during marking. 3777 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity"); 3778 3779 // Record whether this pause is an initial mark. When the current 3780 // thread has completed its logging output and it's safe to signal 3781 // the CM thread, the flag's value in the policy has been reset. 3782 bool should_start_conc_mark = collector_state()->during_initial_mark_pause(); 3783 3784 // Inner scope for scope based logging, timers, and stats collection 3785 { 3786 EvacuationInfo evacuation_info; 3787 3788 if (collector_state()->during_initial_mark_pause()) { 3789 // We are about to start a marking cycle, so we increment the 3790 // full collection counter. 3791 increment_old_marking_cycles_started(); 3792 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3793 } 3794 3795 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 3796 3797 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3798 3799 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 3800 workers()->active_workers(), 3801 Threads::number_of_non_daemon_threads()); 3802 workers()->set_active_workers(active_workers); 3803 3804 double pause_start_sec = os::elapsedTime(); 3805 g1_policy()->note_gc_start(active_workers); 3806 log_gc_header(); 3807 3808 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3809 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3810 3811 // If the secondary_free_list is not empty, append it to the 3812 // free_list. No need to wait for the cleanup operation to finish; 3813 // the region allocation code will check the secondary_free_list 3814 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3815 // set, skip this step so that the region allocation code has to 3816 // get entries from the secondary_free_list. 3817 if (!G1StressConcRegionFreeing) { 3818 append_secondary_free_list_if_not_empty_with_lock(); 3819 } 3820 3821 assert(check_young_list_well_formed(), "young list should be well formed"); 3822 3823 // Don't dynamically change the number of GC threads this early. A value of 3824 // 0 is used to indicate serial work. When parallel work is done, 3825 // it will be set. 3826 3827 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3828 IsGCActiveMark x; 3829 3830 gc_prologue(false); 3831 increment_total_collections(false /* full gc */); 3832 increment_gc_time_stamp(); 3833 3834 verify_before_gc(); 3835 3836 check_bitmaps("GC Start"); 3837 3838 #if defined(COMPILER2) || INCLUDE_JVMCI 3839 DerivedPointerTable::clear(); 3840 #endif 3841 3842 // Please see comment in g1CollectedHeap.hpp and 3843 // G1CollectedHeap::ref_processing_init() to see how 3844 // reference processing currently works in G1. 3845 3846 // Enable discovery in the STW reference processor 3847 if (g1_policy()->should_process_references()) { 3848 ref_processor_stw()->enable_discovery(); 3849 } else { 3850 ref_processor_stw()->disable_discovery(); 3851 } 3852 3853 { 3854 // We want to temporarily turn off discovery by the 3855 // CM ref processor, if necessary, and turn it back on 3856 // on again later if we do. Using a scoped 3857 // NoRefDiscovery object will do this. 3858 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3859 3860 // Forget the current alloc region (we might even choose it to be part 3861 // of the collection set!). 3862 _allocator->release_mutator_alloc_region(); 3863 3864 // We should call this after we retire the mutator alloc 3865 // region(s) so that all the ALLOC / RETIRE events are generated 3866 // before the start GC event. 3867 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3868 3869 // This timing is only used by the ergonomics to handle our pause target. 3870 // It is unclear why this should not include the full pause. We will 3871 // investigate this in CR 7178365. 3872 // 3873 // Preserving the old comment here if that helps the investigation: 3874 // 3875 // The elapsed time induced by the start time below deliberately elides 3876 // the possible verification above. 3877 double sample_start_time_sec = os::elapsedTime(); 3878 3879 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3880 3881 if (collector_state()->during_initial_mark_pause()) { 3882 concurrent_mark()->checkpointRootsInitialPre(); 3883 } 3884 3885 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms); 3886 g1_policy()->finalize_old_cset_part(time_remaining_ms); 3887 3888 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length()); 3889 3890 // Make sure the remembered sets are up to date. This needs to be 3891 // done before register_humongous_regions_with_cset(), because the 3892 // remembered sets are used there to choose eager reclaim candidates. 3893 // If the remembered sets are not up to date we might miss some 3894 // entries that need to be handled. 3895 g1_rem_set()->cleanupHRRS(); 3896 3897 register_humongous_regions_with_cset(); 3898 3899 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3900 3901 _cm->note_start_of_gc(); 3902 // We call this after finalize_cset() to 3903 // ensure that the CSet has been finalized. 3904 _cm->verify_no_cset_oops(); 3905 3906 if (_hr_printer.is_active()) { 3907 HeapRegion* hr = g1_policy()->collection_set(); 3908 while (hr != NULL) { 3909 _hr_printer.cset(hr); 3910 hr = hr->next_in_collection_set(); 3911 } 3912 } 3913 3914 #ifdef ASSERT 3915 VerifyCSetClosure cl; 3916 collection_set_iterate(&cl); 3917 #endif // ASSERT 3918 3919 // Initialize the GC alloc regions. 3920 _allocator->init_gc_alloc_regions(evacuation_info); 3921 3922 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length()); 3923 pre_evacuate_collection_set(); 3924 3925 // Actually do the work... 3926 evacuate_collection_set(evacuation_info, &per_thread_states); 3927 3928 post_evacuate_collection_set(evacuation_info, &per_thread_states); 3929 3930 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 3931 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words); 3932 3933 eagerly_reclaim_humongous_regions(); 3934 3935 g1_policy()->clear_collection_set(); 3936 3937 // Start a new incremental collection set for the next pause. 3938 g1_policy()->start_incremental_cset_building(); 3939 3940 clear_cset_fast_test(); 3941 3942 _young_list->reset_sampled_info(); 3943 3944 // Don't check the whole heap at this point as the 3945 // GC alloc regions from this pause have been tagged 3946 // as survivors and moved on to the survivor list. 3947 // Survivor regions will fail the !is_young() check. 3948 assert(check_young_list_empty(false /* check_heap */), 3949 "young list should be empty"); 3950 3951 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 3952 _young_list->first_survivor_region(), 3953 _young_list->last_survivor_region()); 3954 3955 _young_list->reset_auxilary_lists(); 3956 3957 if (evacuation_failed()) { 3958 set_used(recalculate_used()); 3959 if (_archive_allocator != NULL) { 3960 _archive_allocator->clear_used(); 3961 } 3962 for (uint i = 0; i < ParallelGCThreads; i++) { 3963 if (_evacuation_failed_info_array[i].has_failed()) { 3964 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3965 } 3966 } 3967 } else { 3968 // The "used" of the the collection set have already been subtracted 3969 // when they were freed. Add in the bytes evacuated. 3970 increase_used(g1_policy()->bytes_copied_during_gc()); 3971 } 3972 3973 if (collector_state()->during_initial_mark_pause()) { 3974 // We have to do this before we notify the CM threads that 3975 // they can start working to make sure that all the 3976 // appropriate initialization is done on the CM object. 3977 concurrent_mark()->checkpointRootsInitialPost(); 3978 collector_state()->set_mark_in_progress(true); 3979 // Note that we don't actually trigger the CM thread at 3980 // this point. We do that later when we're sure that 3981 // the current thread has completed its logging output. 3982 } 3983 3984 allocate_dummy_regions(); 3985 3986 _allocator->init_mutator_alloc_region(); 3987 3988 { 3989 size_t expand_bytes = g1_policy()->expansion_amount(); 3990 if (expand_bytes > 0) { 3991 size_t bytes_before = capacity(); 3992 // No need for an ergo verbose message here, 3993 // expansion_amount() does this when it returns a value > 0. 3994 double expand_ms; 3995 if (!expand(expand_bytes, &expand_ms)) { 3996 // We failed to expand the heap. Cannot do anything about it. 3997 } 3998 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 3999 } 4000 } 4001 4002 // We redo the verification but now wrt to the new CSet which 4003 // has just got initialized after the previous CSet was freed. 4004 _cm->verify_no_cset_oops(); 4005 _cm->note_end_of_gc(); 4006 4007 // This timing is only used by the ergonomics to handle our pause target. 4008 // It is unclear why this should not include the full pause. We will 4009 // investigate this in CR 7178365. 4010 double sample_end_time_sec = os::elapsedTime(); 4011 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 4012 size_t total_cards_scanned = per_thread_states.total_cards_scanned(); 4013 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned); 4014 4015 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before()); 4016 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 4017 4018 MemoryService::track_memory_usage(); 4019 4020 // In prepare_for_verify() below we'll need to scan the deferred 4021 // update buffers to bring the RSets up-to-date if 4022 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4023 // the update buffers we'll probably need to scan cards on the 4024 // regions we just allocated to (i.e., the GC alloc 4025 // regions). However, during the last GC we called 4026 // set_saved_mark() on all the GC alloc regions, so card 4027 // scanning might skip the [saved_mark_word()...top()] area of 4028 // those regions (i.e., the area we allocated objects into 4029 // during the last GC). But it shouldn't. Given that 4030 // saved_mark_word() is conditional on whether the GC time stamp 4031 // on the region is current or not, by incrementing the GC time 4032 // stamp here we invalidate all the GC time stamps on all the 4033 // regions and saved_mark_word() will simply return top() for 4034 // all the regions. This is a nicer way of ensuring this rather 4035 // than iterating over the regions and fixing them. In fact, the 4036 // GC time stamp increment here also ensures that 4037 // saved_mark_word() will return top() between pauses, i.e., 4038 // during concurrent refinement. So we don't need the 4039 // is_gc_active() check to decided which top to use when 4040 // scanning cards (see CR 7039627). 4041 increment_gc_time_stamp(); 4042 4043 verify_after_gc(); 4044 check_bitmaps("GC End"); 4045 4046 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4047 ref_processor_stw()->verify_no_references_recorded(); 4048 4049 // CM reference discovery will be re-enabled if necessary. 4050 } 4051 4052 // We should do this after we potentially expand the heap so 4053 // that all the COMMIT events are generated before the end GC 4054 // event, and after we retire the GC alloc regions so that all 4055 // RETIRE events are generated before the end GC event. 4056 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4057 4058 #ifdef TRACESPINNING 4059 ParallelTaskTerminator::print_termination_counts(); 4060 #endif 4061 4062 gc_epilogue(false); 4063 } 4064 4065 // Print the remainder of the GC log output. 4066 log_gc_footer(os::elapsedTime() - pause_start_sec); 4067 4068 // It is not yet to safe to tell the concurrent mark to 4069 // start as we have some optional output below. We don't want the 4070 // output from the concurrent mark thread interfering with this 4071 // logging output either. 4072 4073 _hrm.verify_optional(); 4074 verify_region_sets_optional(); 4075 4076 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats()); 4077 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4078 4079 print_heap_after_gc(); 4080 trace_heap_after_gc(_gc_tracer_stw); 4081 4082 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4083 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4084 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4085 // before any GC notifications are raised. 4086 g1mm()->update_sizes(); 4087 4088 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4089 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4090 _gc_timer_stw->register_gc_end(); 4091 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4092 } 4093 // It should now be safe to tell the concurrent mark thread to start 4094 // without its logging output interfering with the logging output 4095 // that came from the pause. 4096 4097 if (should_start_conc_mark) { 4098 // CAUTION: after the doConcurrentMark() call below, 4099 // the concurrent marking thread(s) could be running 4100 // concurrently with us. Make sure that anything after 4101 // this point does not assume that we are the only GC thread 4102 // running. Note: of course, the actual marking work will 4103 // not start until the safepoint itself is released in 4104 // SuspendibleThreadSet::desynchronize(). 4105 doConcurrentMark(); 4106 } 4107 4108 return true; 4109 } 4110 4111 void G1CollectedHeap::restore_preserved_marks() { 4112 G1RestorePreservedMarksTask rpm_task(_preserved_objs); 4113 workers()->run_task(&rpm_task); 4114 } 4115 4116 void G1CollectedHeap::remove_self_forwarding_pointers() { 4117 G1ParRemoveSelfForwardPtrsTask rsfp_task; 4118 workers()->run_task(&rsfp_task); 4119 } 4120 4121 void G1CollectedHeap::restore_after_evac_failure() { 4122 double remove_self_forwards_start = os::elapsedTime(); 4123 4124 remove_self_forwarding_pointers(); 4125 restore_preserved_marks(); 4126 4127 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4128 } 4129 4130 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 4131 if (!_evacuation_failed) { 4132 _evacuation_failed = true; 4133 } 4134 4135 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 4136 4137 // We want to call the "for_promotion_failure" version only in the 4138 // case of a promotion failure. 4139 if (m->must_be_preserved_for_promotion_failure(obj)) { 4140 OopAndMarkOop elem(obj, m); 4141 _preserved_objs[worker_id].push(elem); 4142 } 4143 } 4144 4145 bool G1ParEvacuateFollowersClosure::offer_termination() { 4146 G1ParScanThreadState* const pss = par_scan_state(); 4147 start_term_time(); 4148 const bool res = terminator()->offer_termination(); 4149 end_term_time(); 4150 return res; 4151 } 4152 4153 void G1ParEvacuateFollowersClosure::do_void() { 4154 G1ParScanThreadState* const pss = par_scan_state(); 4155 pss->trim_queue(); 4156 do { 4157 pss->steal_and_trim_queue(queues()); 4158 } while (!offer_termination()); 4159 } 4160 4161 class G1ParTask : public AbstractGangTask { 4162 protected: 4163 G1CollectedHeap* _g1h; 4164 G1ParScanThreadStateSet* _pss; 4165 RefToScanQueueSet* _queues; 4166 G1RootProcessor* _root_processor; 4167 ParallelTaskTerminator _terminator; 4168 uint _n_workers; 4169 4170 public: 4171 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 4172 : AbstractGangTask("G1 collection"), 4173 _g1h(g1h), 4174 _pss(per_thread_states), 4175 _queues(task_queues), 4176 _root_processor(root_processor), 4177 _terminator(n_workers, _queues), 4178 _n_workers(n_workers) 4179 {} 4180 4181 void work(uint worker_id) { 4182 if (worker_id >= _n_workers) return; // no work needed this round 4183 4184 double start_sec = os::elapsedTime(); 4185 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 4186 4187 { 4188 ResourceMark rm; 4189 HandleMark hm; 4190 4191 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4192 4193 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4194 pss->set_ref_processor(rp); 4195 4196 double start_strong_roots_sec = os::elapsedTime(); 4197 4198 _root_processor->evacuate_roots(pss->closures(), worker_id); 4199 4200 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss); 4201 4202 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid 4203 // treating the nmethods visited to act as roots for concurrent marking. 4204 // We only want to make sure that the oops in the nmethods are adjusted with regard to the 4205 // objects copied by the current evacuation. 4206 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl, 4207 pss->closures()->weak_codeblobs(), 4208 worker_id); 4209 4210 _pss->add_cards_scanned(worker_id, cards_scanned); 4211 4212 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 4213 4214 double term_sec = 0.0; 4215 size_t evac_term_attempts = 0; 4216 { 4217 double start = os::elapsedTime(); 4218 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator); 4219 evac.do_void(); 4220 4221 evac_term_attempts = evac.term_attempts(); 4222 term_sec = evac.term_time(); 4223 double elapsed_sec = os::elapsedTime() - start; 4224 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 4225 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 4226 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 4227 } 4228 4229 assert(pss->queue_is_empty(), "should be empty"); 4230 4231 if (PrintTerminationStats) { 4232 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 4233 size_t lab_waste; 4234 size_t lab_undo_waste; 4235 pss->waste(lab_waste, lab_undo_waste); 4236 _g1h->print_termination_stats(gclog_or_tty, 4237 worker_id, 4238 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 4239 strong_roots_sec * 1000.0, /* strong roots time */ 4240 term_sec * 1000.0, /* evac term time */ 4241 evac_term_attempts, /* evac term attempts */ 4242 lab_waste, /* alloc buffer waste */ 4243 lab_undo_waste /* undo waste */ 4244 ); 4245 } 4246 4247 // Close the inner scope so that the ResourceMark and HandleMark 4248 // destructors are executed here and are included as part of the 4249 // "GC Worker Time". 4250 } 4251 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 4252 } 4253 }; 4254 4255 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) { 4256 st->print_raw_cr("GC Termination Stats"); 4257 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 4258 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo"); 4259 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 4260 } 4261 4262 void G1CollectedHeap::print_termination_stats(outputStream* const st, 4263 uint worker_id, 4264 double elapsed_ms, 4265 double strong_roots_ms, 4266 double term_ms, 4267 size_t term_attempts, 4268 size_t alloc_buffer_waste, 4269 size_t undo_waste) const { 4270 st->print_cr("%3d %9.2f %9.2f %6.2f " 4271 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 4272 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 4273 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 4274 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 4275 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 4276 alloc_buffer_waste * HeapWordSize / K, 4277 undo_waste * HeapWordSize / K); 4278 } 4279 4280 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4281 private: 4282 BoolObjectClosure* _is_alive; 4283 int _initial_string_table_size; 4284 int _initial_symbol_table_size; 4285 4286 bool _process_strings; 4287 int _strings_processed; 4288 int _strings_removed; 4289 4290 bool _process_symbols; 4291 int _symbols_processed; 4292 int _symbols_removed; 4293 4294 public: 4295 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4296 AbstractGangTask("String/Symbol Unlinking"), 4297 _is_alive(is_alive), 4298 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4299 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4300 4301 _initial_string_table_size = StringTable::the_table()->table_size(); 4302 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4303 if (process_strings) { 4304 StringTable::clear_parallel_claimed_index(); 4305 } 4306 if (process_symbols) { 4307 SymbolTable::clear_parallel_claimed_index(); 4308 } 4309 } 4310 4311 ~G1StringSymbolTableUnlinkTask() { 4312 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4313 "claim value %d after unlink less than initial string table size %d", 4314 StringTable::parallel_claimed_index(), _initial_string_table_size); 4315 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4316 "claim value %d after unlink less than initial symbol table size %d", 4317 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size); 4318 4319 if (G1TraceStringSymbolTableScrubbing) { 4320 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4321 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, " 4322 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed", 4323 strings_processed(), strings_removed(), 4324 symbols_processed(), symbols_removed()); 4325 } 4326 } 4327 4328 void work(uint worker_id) { 4329 int strings_processed = 0; 4330 int strings_removed = 0; 4331 int symbols_processed = 0; 4332 int symbols_removed = 0; 4333 if (_process_strings) { 4334 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4335 Atomic::add(strings_processed, &_strings_processed); 4336 Atomic::add(strings_removed, &_strings_removed); 4337 } 4338 if (_process_symbols) { 4339 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 4340 Atomic::add(symbols_processed, &_symbols_processed); 4341 Atomic::add(symbols_removed, &_symbols_removed); 4342 } 4343 } 4344 4345 size_t strings_processed() const { return (size_t)_strings_processed; } 4346 size_t strings_removed() const { return (size_t)_strings_removed; } 4347 4348 size_t symbols_processed() const { return (size_t)_symbols_processed; } 4349 size_t symbols_removed() const { return (size_t)_symbols_removed; } 4350 }; 4351 4352 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 4353 private: 4354 static Monitor* _lock; 4355 4356 BoolObjectClosure* const _is_alive; 4357 const bool _unloading_occurred; 4358 const uint _num_workers; 4359 4360 // Variables used to claim nmethods. 4361 nmethod* _first_nmethod; 4362 volatile nmethod* _claimed_nmethod; 4363 4364 // The list of nmethods that need to be processed by the second pass. 4365 volatile nmethod* _postponed_list; 4366 volatile uint _num_entered_barrier; 4367 4368 public: 4369 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 4370 _is_alive(is_alive), 4371 _unloading_occurred(unloading_occurred), 4372 _num_workers(num_workers), 4373 _first_nmethod(NULL), 4374 _claimed_nmethod(NULL), 4375 _postponed_list(NULL), 4376 _num_entered_barrier(0) 4377 { 4378 nmethod::increase_unloading_clock(); 4379 // Get first alive nmethod 4380 NMethodIterator iter = NMethodIterator(); 4381 if(iter.next_alive()) { 4382 _first_nmethod = iter.method(); 4383 } 4384 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 4385 } 4386 4387 ~G1CodeCacheUnloadingTask() { 4388 CodeCache::verify_clean_inline_caches(); 4389 4390 CodeCache::set_needs_cache_clean(false); 4391 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 4392 4393 CodeCache::verify_icholder_relocations(); 4394 } 4395 4396 private: 4397 void add_to_postponed_list(nmethod* nm) { 4398 nmethod* old; 4399 do { 4400 old = (nmethod*)_postponed_list; 4401 nm->set_unloading_next(old); 4402 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 4403 } 4404 4405 void clean_nmethod(nmethod* nm) { 4406 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 4407 4408 if (postponed) { 4409 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 4410 add_to_postponed_list(nm); 4411 } 4412 4413 // Mark that this thread has been cleaned/unloaded. 4414 // After this call, it will be safe to ask if this nmethod was unloaded or not. 4415 nm->set_unloading_clock(nmethod::global_unloading_clock()); 4416 } 4417 4418 void clean_nmethod_postponed(nmethod* nm) { 4419 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 4420 } 4421 4422 static const int MaxClaimNmethods = 16; 4423 4424 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 4425 nmethod* first; 4426 NMethodIterator last; 4427 4428 do { 4429 *num_claimed_nmethods = 0; 4430 4431 first = (nmethod*)_claimed_nmethod; 4432 last = NMethodIterator(first); 4433 4434 if (first != NULL) { 4435 4436 for (int i = 0; i < MaxClaimNmethods; i++) { 4437 if (!last.next_alive()) { 4438 break; 4439 } 4440 claimed_nmethods[i] = last.method(); 4441 (*num_claimed_nmethods)++; 4442 } 4443 } 4444 4445 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 4446 } 4447 4448 nmethod* claim_postponed_nmethod() { 4449 nmethod* claim; 4450 nmethod* next; 4451 4452 do { 4453 claim = (nmethod*)_postponed_list; 4454 if (claim == NULL) { 4455 return NULL; 4456 } 4457 4458 next = claim->unloading_next(); 4459 4460 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 4461 4462 return claim; 4463 } 4464 4465 public: 4466 // Mark that we're done with the first pass of nmethod cleaning. 4467 void barrier_mark(uint worker_id) { 4468 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4469 _num_entered_barrier++; 4470 if (_num_entered_barrier == _num_workers) { 4471 ml.notify_all(); 4472 } 4473 } 4474 4475 // See if we have to wait for the other workers to 4476 // finish their first-pass nmethod cleaning work. 4477 void barrier_wait(uint worker_id) { 4478 if (_num_entered_barrier < _num_workers) { 4479 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4480 while (_num_entered_barrier < _num_workers) { 4481 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 4482 } 4483 } 4484 } 4485 4486 // Cleaning and unloading of nmethods. Some work has to be postponed 4487 // to the second pass, when we know which nmethods survive. 4488 void work_first_pass(uint worker_id) { 4489 // The first nmethods is claimed by the first worker. 4490 if (worker_id == 0 && _first_nmethod != NULL) { 4491 clean_nmethod(_first_nmethod); 4492 _first_nmethod = NULL; 4493 } 4494 4495 int num_claimed_nmethods; 4496 nmethod* claimed_nmethods[MaxClaimNmethods]; 4497 4498 while (true) { 4499 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 4500 4501 if (num_claimed_nmethods == 0) { 4502 break; 4503 } 4504 4505 for (int i = 0; i < num_claimed_nmethods; i++) { 4506 clean_nmethod(claimed_nmethods[i]); 4507 } 4508 } 4509 } 4510 4511 void work_second_pass(uint worker_id) { 4512 nmethod* nm; 4513 // Take care of postponed nmethods. 4514 while ((nm = claim_postponed_nmethod()) != NULL) { 4515 clean_nmethod_postponed(nm); 4516 } 4517 } 4518 }; 4519 4520 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 4521 4522 class G1KlassCleaningTask : public StackObj { 4523 BoolObjectClosure* _is_alive; 4524 volatile jint _clean_klass_tree_claimed; 4525 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 4526 4527 public: 4528 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 4529 _is_alive(is_alive), 4530 _clean_klass_tree_claimed(0), 4531 _klass_iterator() { 4532 } 4533 4534 private: 4535 bool claim_clean_klass_tree_task() { 4536 if (_clean_klass_tree_claimed) { 4537 return false; 4538 } 4539 4540 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 4541 } 4542 4543 InstanceKlass* claim_next_klass() { 4544 Klass* klass; 4545 do { 4546 klass =_klass_iterator.next_klass(); 4547 } while (klass != NULL && !klass->is_instance_klass()); 4548 4549 // this can be null so don't call InstanceKlass::cast 4550 return static_cast<InstanceKlass*>(klass); 4551 } 4552 4553 public: 4554 4555 void clean_klass(InstanceKlass* ik) { 4556 ik->clean_weak_instanceklass_links(_is_alive); 4557 } 4558 4559 void work() { 4560 ResourceMark rm; 4561 4562 // One worker will clean the subklass/sibling klass tree. 4563 if (claim_clean_klass_tree_task()) { 4564 Klass::clean_subklass_tree(_is_alive); 4565 } 4566 4567 // All workers will help cleaning the classes, 4568 InstanceKlass* klass; 4569 while ((klass = claim_next_klass()) != NULL) { 4570 clean_klass(klass); 4571 } 4572 } 4573 }; 4574 4575 // To minimize the remark pause times, the tasks below are done in parallel. 4576 class G1ParallelCleaningTask : public AbstractGangTask { 4577 private: 4578 G1StringSymbolTableUnlinkTask _string_symbol_task; 4579 G1CodeCacheUnloadingTask _code_cache_task; 4580 G1KlassCleaningTask _klass_cleaning_task; 4581 4582 public: 4583 // The constructor is run in the VMThread. 4584 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 4585 AbstractGangTask("Parallel Cleaning"), 4586 _string_symbol_task(is_alive, process_strings, process_symbols), 4587 _code_cache_task(num_workers, is_alive, unloading_occurred), 4588 _klass_cleaning_task(is_alive) { 4589 } 4590 4591 // The parallel work done by all worker threads. 4592 void work(uint worker_id) { 4593 // Do first pass of code cache cleaning. 4594 _code_cache_task.work_first_pass(worker_id); 4595 4596 // Let the threads mark that the first pass is done. 4597 _code_cache_task.barrier_mark(worker_id); 4598 4599 // Clean the Strings and Symbols. 4600 _string_symbol_task.work(worker_id); 4601 4602 // Wait for all workers to finish the first code cache cleaning pass. 4603 _code_cache_task.barrier_wait(worker_id); 4604 4605 // Do the second code cache cleaning work, which realize on 4606 // the liveness information gathered during the first pass. 4607 _code_cache_task.work_second_pass(worker_id); 4608 4609 // Clean all klasses that were not unloaded. 4610 _klass_cleaning_task.work(); 4611 } 4612 }; 4613 4614 4615 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 4616 bool process_strings, 4617 bool process_symbols, 4618 bool class_unloading_occurred) { 4619 uint n_workers = workers()->active_workers(); 4620 4621 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 4622 n_workers, class_unloading_occurred); 4623 workers()->run_task(&g1_unlink_task); 4624 } 4625 4626 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 4627 bool process_strings, bool process_symbols) { 4628 { 4629 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 4630 workers()->run_task(&g1_unlink_task); 4631 } 4632 4633 if (G1StringDedup::is_enabled()) { 4634 G1StringDedup::unlink(is_alive); 4635 } 4636 } 4637 4638 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 4639 private: 4640 DirtyCardQueueSet* _queue; 4641 G1CollectedHeap* _g1h; 4642 public: 4643 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 4644 _queue(queue), _g1h(g1h) { } 4645 4646 virtual void work(uint worker_id) { 4647 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 4648 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 4649 4650 RedirtyLoggedCardTableEntryClosure cl(_g1h); 4651 _queue->par_apply_closure_to_all_completed_buffers(&cl); 4652 4653 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 4654 } 4655 }; 4656 4657 void G1CollectedHeap::redirty_logged_cards() { 4658 double redirty_logged_cards_start = os::elapsedTime(); 4659 4660 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 4661 dirty_card_queue_set().reset_for_par_iteration(); 4662 workers()->run_task(&redirty_task); 4663 4664 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 4665 dcq.merge_bufferlists(&dirty_card_queue_set()); 4666 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 4667 4668 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 4669 } 4670 4671 // Weak Reference Processing support 4672 4673 // An always "is_alive" closure that is used to preserve referents. 4674 // If the object is non-null then it's alive. Used in the preservation 4675 // of referent objects that are pointed to by reference objects 4676 // discovered by the CM ref processor. 4677 class G1AlwaysAliveClosure: public BoolObjectClosure { 4678 G1CollectedHeap* _g1; 4679 public: 4680 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4681 bool do_object_b(oop p) { 4682 if (p != NULL) { 4683 return true; 4684 } 4685 return false; 4686 } 4687 }; 4688 4689 bool G1STWIsAliveClosure::do_object_b(oop p) { 4690 // An object is reachable if it is outside the collection set, 4691 // or is inside and copied. 4692 return !_g1->is_in_cset(p) || p->is_forwarded(); 4693 } 4694 4695 // Non Copying Keep Alive closure 4696 class G1KeepAliveClosure: public OopClosure { 4697 G1CollectedHeap* _g1; 4698 public: 4699 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4700 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 4701 void do_oop(oop* p) { 4702 oop obj = *p; 4703 assert(obj != NULL, "the caller should have filtered out NULL values"); 4704 4705 const InCSetState cset_state = _g1->in_cset_state(obj); 4706 if (!cset_state.is_in_cset_or_humongous()) { 4707 return; 4708 } 4709 if (cset_state.is_in_cset()) { 4710 assert( obj->is_forwarded(), "invariant" ); 4711 *p = obj->forwardee(); 4712 } else { 4713 assert(!obj->is_forwarded(), "invariant" ); 4714 assert(cset_state.is_humongous(), 4715 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 4716 _g1->set_humongous_is_live(obj); 4717 } 4718 } 4719 }; 4720 4721 // Copying Keep Alive closure - can be called from both 4722 // serial and parallel code as long as different worker 4723 // threads utilize different G1ParScanThreadState instances 4724 // and different queues. 4725 4726 class G1CopyingKeepAliveClosure: public OopClosure { 4727 G1CollectedHeap* _g1h; 4728 OopClosure* _copy_non_heap_obj_cl; 4729 G1ParScanThreadState* _par_scan_state; 4730 4731 public: 4732 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 4733 OopClosure* non_heap_obj_cl, 4734 G1ParScanThreadState* pss): 4735 _g1h(g1h), 4736 _copy_non_heap_obj_cl(non_heap_obj_cl), 4737 _par_scan_state(pss) 4738 {} 4739 4740 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 4741 virtual void do_oop( oop* p) { do_oop_work(p); } 4742 4743 template <class T> void do_oop_work(T* p) { 4744 oop obj = oopDesc::load_decode_heap_oop(p); 4745 4746 if (_g1h->is_in_cset_or_humongous(obj)) { 4747 // If the referent object has been forwarded (either copied 4748 // to a new location or to itself in the event of an 4749 // evacuation failure) then we need to update the reference 4750 // field and, if both reference and referent are in the G1 4751 // heap, update the RSet for the referent. 4752 // 4753 // If the referent has not been forwarded then we have to keep 4754 // it alive by policy. Therefore we have copy the referent. 4755 // 4756 // If the reference field is in the G1 heap then we can push 4757 // on the PSS queue. When the queue is drained (after each 4758 // phase of reference processing) the object and it's followers 4759 // will be copied, the reference field set to point to the 4760 // new location, and the RSet updated. Otherwise we need to 4761 // use the the non-heap or metadata closures directly to copy 4762 // the referent object and update the pointer, while avoiding 4763 // updating the RSet. 4764 4765 if (_g1h->is_in_g1_reserved(p)) { 4766 _par_scan_state->push_on_queue(p); 4767 } else { 4768 assert(!Metaspace::contains((const void*)p), 4769 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)); 4770 _copy_non_heap_obj_cl->do_oop(p); 4771 } 4772 } 4773 } 4774 }; 4775 4776 // Serial drain queue closure. Called as the 'complete_gc' 4777 // closure for each discovered list in some of the 4778 // reference processing phases. 4779 4780 class G1STWDrainQueueClosure: public VoidClosure { 4781 protected: 4782 G1CollectedHeap* _g1h; 4783 G1ParScanThreadState* _par_scan_state; 4784 4785 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4786 4787 public: 4788 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 4789 _g1h(g1h), 4790 _par_scan_state(pss) 4791 { } 4792 4793 void do_void() { 4794 G1ParScanThreadState* const pss = par_scan_state(); 4795 pss->trim_queue(); 4796 } 4797 }; 4798 4799 // Parallel Reference Processing closures 4800 4801 // Implementation of AbstractRefProcTaskExecutor for parallel reference 4802 // processing during G1 evacuation pauses. 4803 4804 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 4805 private: 4806 G1CollectedHeap* _g1h; 4807 G1ParScanThreadStateSet* _pss; 4808 RefToScanQueueSet* _queues; 4809 WorkGang* _workers; 4810 uint _active_workers; 4811 4812 public: 4813 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 4814 G1ParScanThreadStateSet* per_thread_states, 4815 WorkGang* workers, 4816 RefToScanQueueSet *task_queues, 4817 uint n_workers) : 4818 _g1h(g1h), 4819 _pss(per_thread_states), 4820 _queues(task_queues), 4821 _workers(workers), 4822 _active_workers(n_workers) 4823 { 4824 assert(n_workers > 0, "shouldn't call this otherwise"); 4825 } 4826 4827 // Executes the given task using concurrent marking worker threads. 4828 virtual void execute(ProcessTask& task); 4829 virtual void execute(EnqueueTask& task); 4830 }; 4831 4832 // Gang task for possibly parallel reference processing 4833 4834 class G1STWRefProcTaskProxy: public AbstractGangTask { 4835 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 4836 ProcessTask& _proc_task; 4837 G1CollectedHeap* _g1h; 4838 G1ParScanThreadStateSet* _pss; 4839 RefToScanQueueSet* _task_queues; 4840 ParallelTaskTerminator* _terminator; 4841 4842 public: 4843 G1STWRefProcTaskProxy(ProcessTask& proc_task, 4844 G1CollectedHeap* g1h, 4845 G1ParScanThreadStateSet* per_thread_states, 4846 RefToScanQueueSet *task_queues, 4847 ParallelTaskTerminator* terminator) : 4848 AbstractGangTask("Process reference objects in parallel"), 4849 _proc_task(proc_task), 4850 _g1h(g1h), 4851 _pss(per_thread_states), 4852 _task_queues(task_queues), 4853 _terminator(terminator) 4854 {} 4855 4856 virtual void work(uint worker_id) { 4857 // The reference processing task executed by a single worker. 4858 ResourceMark rm; 4859 HandleMark hm; 4860 4861 G1STWIsAliveClosure is_alive(_g1h); 4862 4863 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4864 pss->set_ref_processor(NULL); 4865 4866 // Keep alive closure. 4867 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 4868 4869 // Complete GC closure 4870 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator); 4871 4872 // Call the reference processing task's work routine. 4873 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 4874 4875 // Note we cannot assert that the refs array is empty here as not all 4876 // of the processing tasks (specifically phase2 - pp2_work) execute 4877 // the complete_gc closure (which ordinarily would drain the queue) so 4878 // the queue may not be empty. 4879 } 4880 }; 4881 4882 // Driver routine for parallel reference processing. 4883 // Creates an instance of the ref processing gang 4884 // task and has the worker threads execute it. 4885 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 4886 assert(_workers != NULL, "Need parallel worker threads."); 4887 4888 ParallelTaskTerminator terminator(_active_workers, _queues); 4889 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 4890 4891 _workers->run_task(&proc_task_proxy); 4892 } 4893 4894 // Gang task for parallel reference enqueueing. 4895 4896 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 4897 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 4898 EnqueueTask& _enq_task; 4899 4900 public: 4901 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 4902 AbstractGangTask("Enqueue reference objects in parallel"), 4903 _enq_task(enq_task) 4904 { } 4905 4906 virtual void work(uint worker_id) { 4907 _enq_task.work(worker_id); 4908 } 4909 }; 4910 4911 // Driver routine for parallel reference enqueueing. 4912 // Creates an instance of the ref enqueueing gang 4913 // task and has the worker threads execute it. 4914 4915 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 4916 assert(_workers != NULL, "Need parallel worker threads."); 4917 4918 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 4919 4920 _workers->run_task(&enq_task_proxy); 4921 } 4922 4923 // End of weak reference support closures 4924 4925 // Abstract task used to preserve (i.e. copy) any referent objects 4926 // that are in the collection set and are pointed to by reference 4927 // objects discovered by the CM ref processor. 4928 4929 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 4930 protected: 4931 G1CollectedHeap* _g1h; 4932 G1ParScanThreadStateSet* _pss; 4933 RefToScanQueueSet* _queues; 4934 ParallelTaskTerminator _terminator; 4935 uint _n_workers; 4936 4937 public: 4938 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) : 4939 AbstractGangTask("ParPreserveCMReferents"), 4940 _g1h(g1h), 4941 _pss(per_thread_states), 4942 _queues(task_queues), 4943 _terminator(workers, _queues), 4944 _n_workers(workers) 4945 { } 4946 4947 void work(uint worker_id) { 4948 ResourceMark rm; 4949 HandleMark hm; 4950 4951 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4952 pss->set_ref_processor(NULL); 4953 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 4954 4955 // Is alive closure 4956 G1AlwaysAliveClosure always_alive(_g1h); 4957 4958 // Copying keep alive closure. Applied to referent objects that need 4959 // to be copied. 4960 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 4961 4962 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 4963 4964 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 4965 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 4966 4967 // limit is set using max_num_q() - which was set using ParallelGCThreads. 4968 // So this must be true - but assert just in case someone decides to 4969 // change the worker ids. 4970 assert(worker_id < limit, "sanity"); 4971 assert(!rp->discovery_is_atomic(), "check this code"); 4972 4973 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 4974 for (uint idx = worker_id; idx < limit; idx += stride) { 4975 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 4976 4977 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 4978 while (iter.has_next()) { 4979 // Since discovery is not atomic for the CM ref processor, we 4980 // can see some null referent objects. 4981 iter.load_ptrs(DEBUG_ONLY(true)); 4982 oop ref = iter.obj(); 4983 4984 // This will filter nulls. 4985 if (iter.is_referent_alive()) { 4986 iter.make_referent_alive(); 4987 } 4988 iter.move_to_next(); 4989 } 4990 } 4991 4992 // Drain the queue - which may cause stealing 4993 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator); 4994 drain_queue.do_void(); 4995 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 4996 assert(pss->queue_is_empty(), "should be"); 4997 } 4998 }; 4999 5000 void G1CollectedHeap::process_weak_jni_handles() { 5001 double ref_proc_start = os::elapsedTime(); 5002 5003 G1STWIsAliveClosure is_alive(this); 5004 G1KeepAliveClosure keep_alive(this); 5005 JNIHandles::weak_oops_do(&is_alive, &keep_alive); 5006 5007 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5008 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5009 } 5010 5011 // Weak Reference processing during an evacuation pause (part 1). 5012 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 5013 double ref_proc_start = os::elapsedTime(); 5014 5015 ReferenceProcessor* rp = _ref_processor_stw; 5016 assert(rp->discovery_enabled(), "should have been enabled"); 5017 5018 // Any reference objects, in the collection set, that were 'discovered' 5019 // by the CM ref processor should have already been copied (either by 5020 // applying the external root copy closure to the discovered lists, or 5021 // by following an RSet entry). 5022 // 5023 // But some of the referents, that are in the collection set, that these 5024 // reference objects point to may not have been copied: the STW ref 5025 // processor would have seen that the reference object had already 5026 // been 'discovered' and would have skipped discovering the reference, 5027 // but would not have treated the reference object as a regular oop. 5028 // As a result the copy closure would not have been applied to the 5029 // referent object. 5030 // 5031 // We need to explicitly copy these referent objects - the references 5032 // will be processed at the end of remarking. 5033 // 5034 // We also need to do this copying before we process the reference 5035 // objects discovered by the STW ref processor in case one of these 5036 // referents points to another object which is also referenced by an 5037 // object discovered by the STW ref processor. 5038 5039 uint no_of_gc_workers = workers()->active_workers(); 5040 5041 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5042 per_thread_states, 5043 no_of_gc_workers, 5044 _task_queues); 5045 5046 workers()->run_task(&keep_cm_referents); 5047 5048 // Closure to test whether a referent is alive. 5049 G1STWIsAliveClosure is_alive(this); 5050 5051 // Even when parallel reference processing is enabled, the processing 5052 // of JNI refs is serial and performed serially by the current thread 5053 // rather than by a worker. The following PSS will be used for processing 5054 // JNI refs. 5055 5056 // Use only a single queue for this PSS. 5057 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 5058 pss->set_ref_processor(NULL); 5059 assert(pss->queue_is_empty(), "pre-condition"); 5060 5061 // Keep alive closure. 5062 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss); 5063 5064 // Serial Complete GC closure 5065 G1STWDrainQueueClosure drain_queue(this, pss); 5066 5067 // Setup the soft refs policy... 5068 rp->setup_policy(false); 5069 5070 ReferenceProcessorStats stats; 5071 if (!rp->processing_is_mt()) { 5072 // Serial reference processing... 5073 stats = rp->process_discovered_references(&is_alive, 5074 &keep_alive, 5075 &drain_queue, 5076 NULL, 5077 _gc_timer_stw); 5078 } else { 5079 // Parallel reference processing 5080 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5081 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5082 5083 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers); 5084 stats = rp->process_discovered_references(&is_alive, 5085 &keep_alive, 5086 &drain_queue, 5087 &par_task_executor, 5088 _gc_timer_stw); 5089 } 5090 5091 _gc_tracer_stw->report_gc_reference_stats(stats); 5092 5093 // We have completed copying any necessary live referent objects. 5094 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 5095 5096 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5097 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5098 } 5099 5100 // Weak Reference processing during an evacuation pause (part 2). 5101 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 5102 double ref_enq_start = os::elapsedTime(); 5103 5104 ReferenceProcessor* rp = _ref_processor_stw; 5105 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5106 5107 // Now enqueue any remaining on the discovered lists on to 5108 // the pending list. 5109 if (!rp->processing_is_mt()) { 5110 // Serial reference processing... 5111 rp->enqueue_discovered_references(); 5112 } else { 5113 // Parallel reference enqueueing 5114 5115 uint n_workers = workers()->active_workers(); 5116 5117 assert(rp->num_q() == n_workers, "sanity"); 5118 assert(n_workers <= rp->max_num_q(), "sanity"); 5119 5120 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers); 5121 rp->enqueue_discovered_references(&par_task_executor); 5122 } 5123 5124 rp->verify_no_references_recorded(); 5125 assert(!rp->discovery_enabled(), "should have been disabled"); 5126 5127 // FIXME 5128 // CM's reference processing also cleans up the string and symbol tables. 5129 // Should we do that here also? We could, but it is a serial operation 5130 // and could significantly increase the pause time. 5131 5132 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5133 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5134 } 5135 5136 void G1CollectedHeap::pre_evacuate_collection_set() { 5137 _expand_heap_after_alloc_failure = true; 5138 _evacuation_failed = false; 5139 5140 // Disable the hot card cache. 5141 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5142 hot_card_cache->reset_hot_cache_claimed_index(); 5143 hot_card_cache->set_use_cache(false); 5144 5145 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5146 } 5147 5148 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 5149 // Should G1EvacuationFailureALot be in effect for this GC? 5150 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5151 5152 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5153 double start_par_time_sec = os::elapsedTime(); 5154 double end_par_time_sec; 5155 5156 { 5157 const uint n_workers = workers()->active_workers(); 5158 G1RootProcessor root_processor(this, n_workers); 5159 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 5160 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5161 if (collector_state()->during_initial_mark_pause()) { 5162 ClassLoaderDataGraph::clear_claimed_marks(); 5163 } 5164 5165 // The individual threads will set their evac-failure closures. 5166 if (PrintTerminationStats) { 5167 print_termination_stats_hdr(gclog_or_tty); 5168 } 5169 5170 workers()->run_task(&g1_par_task); 5171 end_par_time_sec = os::elapsedTime(); 5172 5173 // Closing the inner scope will execute the destructor 5174 // for the G1RootProcessor object. We record the current 5175 // elapsed time before closing the scope so that time 5176 // taken for the destructor is NOT included in the 5177 // reported parallel time. 5178 } 5179 5180 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 5181 5182 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5183 phase_times->record_par_time(par_time_ms); 5184 5185 double code_root_fixup_time_ms = 5186 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5187 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 5188 } 5189 5190 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 5191 // Process any discovered reference objects - we have 5192 // to do this _before_ we retire the GC alloc regions 5193 // as we may have to copy some 'reachable' referent 5194 // objects (and their reachable sub-graphs) that were 5195 // not copied during the pause. 5196 if (g1_policy()->should_process_references()) { 5197 process_discovered_references(per_thread_states); 5198 } else { 5199 ref_processor_stw()->verify_no_references_recorded(); 5200 process_weak_jni_handles(); 5201 } 5202 5203 if (G1StringDedup::is_enabled()) { 5204 double fixup_start = os::elapsedTime(); 5205 5206 G1STWIsAliveClosure is_alive(this); 5207 G1KeepAliveClosure keep_alive(this); 5208 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times()); 5209 5210 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 5211 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms); 5212 } 5213 5214 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5215 5216 if (evacuation_failed()) { 5217 restore_after_evac_failure(); 5218 5219 // Reset the G1EvacuationFailureALot counters and flags 5220 // Note: the values are reset only when an actual 5221 // evacuation failure occurs. 5222 NOT_PRODUCT(reset_evacuation_should_fail();) 5223 } 5224 5225 // Enqueue any remaining references remaining on the STW 5226 // reference processor's discovered lists. We need to do 5227 // this after the card table is cleaned (and verified) as 5228 // the act of enqueueing entries on to the pending list 5229 // will log these updates (and dirty their associated 5230 // cards). We need these updates logged to update any 5231 // RSets. 5232 if (g1_policy()->should_process_references()) { 5233 enqueue_discovered_references(per_thread_states); 5234 } else { 5235 g1_policy()->phase_times()->record_ref_enq_time(0); 5236 } 5237 5238 _allocator->release_gc_alloc_regions(evacuation_info); 5239 5240 per_thread_states->flush(); 5241 5242 record_obj_copy_mem_stats(); 5243 5244 _survivor_evac_stats.adjust_desired_plab_sz(); 5245 _old_evac_stats.adjust_desired_plab_sz(); 5246 5247 // Reset and re-enable the hot card cache. 5248 // Note the counts for the cards in the regions in the 5249 // collection set are reset when the collection set is freed. 5250 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5251 hot_card_cache->reset_hot_cache(); 5252 hot_card_cache->set_use_cache(true); 5253 5254 purge_code_root_memory(); 5255 5256 redirty_logged_cards(); 5257 #if defined(COMPILER2) || INCLUDE_JVMCI 5258 DerivedPointerTable::update_pointers(); 5259 #endif 5260 } 5261 5262 void G1CollectedHeap::record_obj_copy_mem_stats() { 5263 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 5264 5265 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 5266 create_g1_evac_summary(&_old_evac_stats)); 5267 } 5268 5269 void G1CollectedHeap::free_region(HeapRegion* hr, 5270 FreeRegionList* free_list, 5271 bool par, 5272 bool locked) { 5273 assert(!hr->is_free(), "the region should not be free"); 5274 assert(!hr->is_empty(), "the region should not be empty"); 5275 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 5276 assert(free_list != NULL, "pre-condition"); 5277 5278 if (G1VerifyBitmaps) { 5279 MemRegion mr(hr->bottom(), hr->end()); 5280 concurrent_mark()->clearRangePrevBitmap(mr); 5281 } 5282 5283 // Clear the card counts for this region. 5284 // Note: we only need to do this if the region is not young 5285 // (since we don't refine cards in young regions). 5286 if (!hr->is_young()) { 5287 _cg1r->hot_card_cache()->reset_card_counts(hr); 5288 } 5289 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5290 free_list->add_ordered(hr); 5291 } 5292 5293 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5294 FreeRegionList* free_list, 5295 bool par) { 5296 assert(hr->is_humongous(), "this is only for humongous regions"); 5297 assert(free_list != NULL, "pre-condition"); 5298 hr->clear_humongous(); 5299 free_region(hr, free_list, par); 5300 } 5301 5302 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 5303 const HeapRegionSetCount& humongous_regions_removed) { 5304 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5305 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5306 _old_set.bulk_remove(old_regions_removed); 5307 _humongous_set.bulk_remove(humongous_regions_removed); 5308 } 5309 5310 } 5311 5312 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 5313 assert(list != NULL, "list can't be null"); 5314 if (!list->is_empty()) { 5315 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5316 _hrm.insert_list_into_free_list(list); 5317 } 5318 } 5319 5320 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 5321 decrease_used(bytes); 5322 } 5323 5324 class G1ParCleanupCTTask : public AbstractGangTask { 5325 G1SATBCardTableModRefBS* _ct_bs; 5326 G1CollectedHeap* _g1h; 5327 HeapRegion* volatile _su_head; 5328 public: 5329 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 5330 G1CollectedHeap* g1h) : 5331 AbstractGangTask("G1 Par Cleanup CT Task"), 5332 _ct_bs(ct_bs), _g1h(g1h) { } 5333 5334 void work(uint worker_id) { 5335 HeapRegion* r; 5336 while (r = _g1h->pop_dirty_cards_region()) { 5337 clear_cards(r); 5338 } 5339 } 5340 5341 void clear_cards(HeapRegion* r) { 5342 // Cards of the survivors should have already been dirtied. 5343 if (!r->is_survivor()) { 5344 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5345 } 5346 } 5347 }; 5348 5349 #ifndef PRODUCT 5350 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5351 G1CollectedHeap* _g1h; 5352 G1SATBCardTableModRefBS* _ct_bs; 5353 public: 5354 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 5355 : _g1h(g1h), _ct_bs(ct_bs) { } 5356 virtual bool doHeapRegion(HeapRegion* r) { 5357 if (r->is_survivor()) { 5358 _g1h->verify_dirty_region(r); 5359 } else { 5360 _g1h->verify_not_dirty_region(r); 5361 } 5362 return false; 5363 } 5364 }; 5365 5366 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5367 // All of the region should be clean. 5368 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5369 MemRegion mr(hr->bottom(), hr->end()); 5370 ct_bs->verify_not_dirty_region(mr); 5371 } 5372 5373 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5374 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5375 // dirty allocated blocks as they allocate them. The thread that 5376 // retires each region and replaces it with a new one will do a 5377 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5378 // not dirty that area (one less thing to have to do while holding 5379 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5380 // is dirty. 5381 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5382 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5383 if (hr->is_young()) { 5384 ct_bs->verify_g1_young_region(mr); 5385 } else { 5386 ct_bs->verify_dirty_region(mr); 5387 } 5388 } 5389 5390 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5391 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5392 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5393 verify_dirty_region(hr); 5394 } 5395 } 5396 5397 void G1CollectedHeap::verify_dirty_young_regions() { 5398 verify_dirty_young_list(_young_list->first_region()); 5399 } 5400 5401 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 5402 HeapWord* tams, HeapWord* end) { 5403 guarantee(tams <= end, 5404 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end)); 5405 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 5406 if (result < end) { 5407 gclog_or_tty->cr(); 5408 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT, 5409 bitmap_name, p2i(result)); 5410 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT, 5411 bitmap_name, p2i(tams), p2i(end)); 5412 return false; 5413 } 5414 return true; 5415 } 5416 5417 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 5418 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 5419 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 5420 5421 HeapWord* bottom = hr->bottom(); 5422 HeapWord* ptams = hr->prev_top_at_mark_start(); 5423 HeapWord* ntams = hr->next_top_at_mark_start(); 5424 HeapWord* end = hr->end(); 5425 5426 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 5427 5428 bool res_n = true; 5429 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 5430 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 5431 // if we happen to be in that state. 5432 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) { 5433 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 5434 } 5435 if (!res_p || !res_n) { 5436 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT, 5437 HR_FORMAT_PARAMS(hr)); 5438 gclog_or_tty->print_cr("#### Caller: %s", caller); 5439 return false; 5440 } 5441 return true; 5442 } 5443 5444 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 5445 if (!G1VerifyBitmaps) return; 5446 5447 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 5448 } 5449 5450 class G1VerifyBitmapClosure : public HeapRegionClosure { 5451 private: 5452 const char* _caller; 5453 G1CollectedHeap* _g1h; 5454 bool _failures; 5455 5456 public: 5457 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 5458 _caller(caller), _g1h(g1h), _failures(false) { } 5459 5460 bool failures() { return _failures; } 5461 5462 virtual bool doHeapRegion(HeapRegion* hr) { 5463 bool result = _g1h->verify_bitmaps(_caller, hr); 5464 if (!result) { 5465 _failures = true; 5466 } 5467 return false; 5468 } 5469 }; 5470 5471 void G1CollectedHeap::check_bitmaps(const char* caller) { 5472 if (!G1VerifyBitmaps) return; 5473 5474 G1VerifyBitmapClosure cl(caller, this); 5475 heap_region_iterate(&cl); 5476 guarantee(!cl.failures(), "bitmap verification"); 5477 } 5478 5479 class G1CheckCSetFastTableClosure : public HeapRegionClosure { 5480 private: 5481 bool _failures; 5482 public: 5483 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { } 5484 5485 virtual bool doHeapRegion(HeapRegion* hr) { 5486 uint i = hr->hrm_index(); 5487 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i); 5488 if (hr->is_humongous()) { 5489 if (hr->in_collection_set()) { 5490 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i); 5491 _failures = true; 5492 return true; 5493 } 5494 if (cset_state.is_in_cset()) { 5495 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i); 5496 _failures = true; 5497 return true; 5498 } 5499 if (hr->is_continues_humongous() && cset_state.is_humongous()) { 5500 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i); 5501 _failures = true; 5502 return true; 5503 } 5504 } else { 5505 if (cset_state.is_humongous()) { 5506 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i); 5507 _failures = true; 5508 return true; 5509 } 5510 if (hr->in_collection_set() != cset_state.is_in_cset()) { 5511 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u", 5512 hr->in_collection_set(), cset_state.value(), i); 5513 _failures = true; 5514 return true; 5515 } 5516 if (cset_state.is_in_cset()) { 5517 if (hr->is_young() != (cset_state.is_young())) { 5518 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u", 5519 hr->is_young(), cset_state.value(), i); 5520 _failures = true; 5521 return true; 5522 } 5523 if (hr->is_old() != (cset_state.is_old())) { 5524 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u", 5525 hr->is_old(), cset_state.value(), i); 5526 _failures = true; 5527 return true; 5528 } 5529 } 5530 } 5531 return false; 5532 } 5533 5534 bool failures() const { return _failures; } 5535 }; 5536 5537 bool G1CollectedHeap::check_cset_fast_test() { 5538 G1CheckCSetFastTableClosure cl; 5539 _hrm.iterate(&cl); 5540 return !cl.failures(); 5541 } 5542 #endif // PRODUCT 5543 5544 void G1CollectedHeap::cleanUpCardTable() { 5545 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5546 double start = os::elapsedTime(); 5547 5548 { 5549 // Iterate over the dirty cards region list. 5550 G1ParCleanupCTTask cleanup_task(ct_bs, this); 5551 5552 workers()->run_task(&cleanup_task); 5553 #ifndef PRODUCT 5554 if (G1VerifyCTCleanup || VerifyAfterGC) { 5555 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 5556 heap_region_iterate(&cleanup_verifier); 5557 } 5558 #endif 5559 } 5560 5561 double elapsed = os::elapsedTime() - start; 5562 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 5563 } 5564 5565 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 5566 size_t pre_used = 0; 5567 FreeRegionList local_free_list("Local List for CSet Freeing"); 5568 5569 double young_time_ms = 0.0; 5570 double non_young_time_ms = 0.0; 5571 5572 // Since the collection set is a superset of the the young list, 5573 // all we need to do to clear the young list is clear its 5574 // head and length, and unlink any young regions in the code below 5575 _young_list->clear(); 5576 5577 G1CollectorPolicy* policy = g1_policy(); 5578 5579 double start_sec = os::elapsedTime(); 5580 bool non_young = true; 5581 5582 HeapRegion* cur = cs_head; 5583 int age_bound = -1; 5584 size_t rs_lengths = 0; 5585 5586 while (cur != NULL) { 5587 assert(!is_on_master_free_list(cur), "sanity"); 5588 if (non_young) { 5589 if (cur->is_young()) { 5590 double end_sec = os::elapsedTime(); 5591 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5592 non_young_time_ms += elapsed_ms; 5593 5594 start_sec = os::elapsedTime(); 5595 non_young = false; 5596 } 5597 } else { 5598 if (!cur->is_young()) { 5599 double end_sec = os::elapsedTime(); 5600 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5601 young_time_ms += elapsed_ms; 5602 5603 start_sec = os::elapsedTime(); 5604 non_young = true; 5605 } 5606 } 5607 5608 rs_lengths += cur->rem_set()->occupied_locked(); 5609 5610 HeapRegion* next = cur->next_in_collection_set(); 5611 assert(cur->in_collection_set(), "bad CS"); 5612 cur->set_next_in_collection_set(NULL); 5613 clear_in_cset(cur); 5614 5615 if (cur->is_young()) { 5616 int index = cur->young_index_in_cset(); 5617 assert(index != -1, "invariant"); 5618 assert((uint) index < policy->young_cset_region_length(), "invariant"); 5619 size_t words_survived = surviving_young_words[index]; 5620 cur->record_surv_words_in_group(words_survived); 5621 5622 // At this point the we have 'popped' cur from the collection set 5623 // (linked via next_in_collection_set()) but it is still in the 5624 // young list (linked via next_young_region()). Clear the 5625 // _next_young_region field. 5626 cur->set_next_young_region(NULL); 5627 } else { 5628 int index = cur->young_index_in_cset(); 5629 assert(index == -1, "invariant"); 5630 } 5631 5632 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 5633 (!cur->is_young() && cur->young_index_in_cset() == -1), 5634 "invariant" ); 5635 5636 if (!cur->evacuation_failed()) { 5637 MemRegion used_mr = cur->used_region(); 5638 5639 // And the region is empty. 5640 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 5641 pre_used += cur->used(); 5642 free_region(cur, &local_free_list, false /* par */, true /* locked */); 5643 } else { 5644 cur->uninstall_surv_rate_group(); 5645 if (cur->is_young()) { 5646 cur->set_young_index_in_cset(-1); 5647 } 5648 cur->set_evacuation_failed(false); 5649 // When moving a young gen region to old gen, we "allocate" that whole region 5650 // there. This is in addition to any already evacuated objects. Notify the 5651 // policy about that. 5652 // Old gen regions do not cause an additional allocation: both the objects 5653 // still in the region and the ones already moved are accounted for elsewhere. 5654 if (cur->is_young()) { 5655 policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes); 5656 } 5657 // The region is now considered to be old. 5658 cur->set_old(); 5659 // Do some allocation statistics accounting. Regions that failed evacuation 5660 // are always made old, so there is no need to update anything in the young 5661 // gen statistics, but we need to update old gen statistics. 5662 size_t used_words = cur->marked_bytes() / HeapWordSize; 5663 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words); 5664 _old_set.add(cur); 5665 evacuation_info.increment_collectionset_used_after(cur->used()); 5666 } 5667 cur = next; 5668 } 5669 5670 evacuation_info.set_regions_freed(local_free_list.length()); 5671 policy->record_max_rs_lengths(rs_lengths); 5672 policy->cset_regions_freed(); 5673 5674 double end_sec = os::elapsedTime(); 5675 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5676 5677 if (non_young) { 5678 non_young_time_ms += elapsed_ms; 5679 } else { 5680 young_time_ms += elapsed_ms; 5681 } 5682 5683 prepend_to_freelist(&local_free_list); 5684 decrement_summary_bytes(pre_used); 5685 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 5686 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 5687 } 5688 5689 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 5690 private: 5691 FreeRegionList* _free_region_list; 5692 HeapRegionSet* _proxy_set; 5693 HeapRegionSetCount _humongous_regions_removed; 5694 size_t _freed_bytes; 5695 public: 5696 5697 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 5698 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 5699 } 5700 5701 virtual bool doHeapRegion(HeapRegion* r) { 5702 if (!r->is_starts_humongous()) { 5703 return false; 5704 } 5705 5706 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 5707 5708 oop obj = (oop)r->bottom(); 5709 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 5710 5711 // The following checks whether the humongous object is live are sufficient. 5712 // The main additional check (in addition to having a reference from the roots 5713 // or the young gen) is whether the humongous object has a remembered set entry. 5714 // 5715 // A humongous object cannot be live if there is no remembered set for it 5716 // because: 5717 // - there can be no references from within humongous starts regions referencing 5718 // the object because we never allocate other objects into them. 5719 // (I.e. there are no intra-region references that may be missed by the 5720 // remembered set) 5721 // - as soon there is a remembered set entry to the humongous starts region 5722 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 5723 // until the end of a concurrent mark. 5724 // 5725 // It is not required to check whether the object has been found dead by marking 5726 // or not, in fact it would prevent reclamation within a concurrent cycle, as 5727 // all objects allocated during that time are considered live. 5728 // SATB marking is even more conservative than the remembered set. 5729 // So if at this point in the collection there is no remembered set entry, 5730 // nobody has a reference to it. 5731 // At the start of collection we flush all refinement logs, and remembered sets 5732 // are completely up-to-date wrt to references to the humongous object. 5733 // 5734 // Other implementation considerations: 5735 // - never consider object arrays at this time because they would pose 5736 // considerable effort for cleaning up the the remembered sets. This is 5737 // required because stale remembered sets might reference locations that 5738 // are currently allocated into. 5739 uint region_idx = r->hrm_index(); 5740 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 5741 !r->rem_set()->is_empty()) { 5742 5743 if (G1TraceEagerReclaimHumongousObjects) { 5744 gclog_or_tty->print_cr("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", 5745 region_idx, 5746 (size_t)obj->size() * HeapWordSize, 5747 p2i(r->bottom()), 5748 r->rem_set()->occupied(), 5749 r->rem_set()->strong_code_roots_list_length(), 5750 next_bitmap->isMarked(r->bottom()), 5751 g1h->is_humongous_reclaim_candidate(region_idx), 5752 obj->is_typeArray() 5753 ); 5754 } 5755 5756 return false; 5757 } 5758 5759 guarantee(obj->is_typeArray(), 5760 "Only eagerly reclaiming type arrays is supported, but the object " 5761 PTR_FORMAT " is not.", p2i(r->bottom())); 5762 5763 if (G1TraceEagerReclaimHumongousObjects) { 5764 gclog_or_tty->print_cr("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", 5765 region_idx, 5766 (size_t)obj->size() * HeapWordSize, 5767 p2i(r->bottom()), 5768 r->rem_set()->occupied(), 5769 r->rem_set()->strong_code_roots_list_length(), 5770 next_bitmap->isMarked(r->bottom()), 5771 g1h->is_humongous_reclaim_candidate(region_idx), 5772 obj->is_typeArray() 5773 ); 5774 } 5775 // Need to clear mark bit of the humongous object if already set. 5776 if (next_bitmap->isMarked(r->bottom())) { 5777 next_bitmap->clear(r->bottom()); 5778 } 5779 do { 5780 HeapRegion* next = g1h->next_region_in_humongous(r); 5781 _freed_bytes += r->used(); 5782 r->set_containing_set(NULL); 5783 _humongous_regions_removed.increment(1u, r->capacity()); 5784 g1h->free_humongous_region(r, _free_region_list, false); 5785 r = next; 5786 } while (r != NULL); 5787 5788 return false; 5789 } 5790 5791 HeapRegionSetCount& humongous_free_count() { 5792 return _humongous_regions_removed; 5793 } 5794 5795 size_t bytes_freed() const { 5796 return _freed_bytes; 5797 } 5798 5799 size_t humongous_reclaimed() const { 5800 return _humongous_regions_removed.length(); 5801 } 5802 }; 5803 5804 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 5805 assert_at_safepoint(true); 5806 5807 if (!G1EagerReclaimHumongousObjects || 5808 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) { 5809 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 5810 return; 5811 } 5812 5813 double start_time = os::elapsedTime(); 5814 5815 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 5816 5817 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 5818 heap_region_iterate(&cl); 5819 5820 HeapRegionSetCount empty_set; 5821 remove_from_old_sets(empty_set, cl.humongous_free_count()); 5822 5823 G1HRPrinter* hrp = hr_printer(); 5824 if (hrp->is_active()) { 5825 FreeRegionListIterator iter(&local_cleanup_list); 5826 while (iter.more_available()) { 5827 HeapRegion* hr = iter.get_next(); 5828 hrp->cleanup(hr); 5829 } 5830 } 5831 5832 prepend_to_freelist(&local_cleanup_list); 5833 decrement_summary_bytes(cl.bytes_freed()); 5834 5835 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 5836 cl.humongous_reclaimed()); 5837 } 5838 5839 // This routine is similar to the above but does not record 5840 // any policy statistics or update free lists; we are abandoning 5841 // the current incremental collection set in preparation of a 5842 // full collection. After the full GC we will start to build up 5843 // the incremental collection set again. 5844 // This is only called when we're doing a full collection 5845 // and is immediately followed by the tearing down of the young list. 5846 5847 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 5848 HeapRegion* cur = cs_head; 5849 5850 while (cur != NULL) { 5851 HeapRegion* next = cur->next_in_collection_set(); 5852 assert(cur->in_collection_set(), "bad CS"); 5853 cur->set_next_in_collection_set(NULL); 5854 clear_in_cset(cur); 5855 cur->set_young_index_in_cset(-1); 5856 cur = next; 5857 } 5858 } 5859 5860 void G1CollectedHeap::set_free_regions_coming() { 5861 if (G1ConcRegionFreeingVerbose) { 5862 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 5863 "setting free regions coming"); 5864 } 5865 5866 assert(!free_regions_coming(), "pre-condition"); 5867 _free_regions_coming = true; 5868 } 5869 5870 void G1CollectedHeap::reset_free_regions_coming() { 5871 assert(free_regions_coming(), "pre-condition"); 5872 5873 { 5874 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5875 _free_regions_coming = false; 5876 SecondaryFreeList_lock->notify_all(); 5877 } 5878 5879 if (G1ConcRegionFreeingVerbose) { 5880 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 5881 "reset free regions coming"); 5882 } 5883 } 5884 5885 void G1CollectedHeap::wait_while_free_regions_coming() { 5886 // Most of the time we won't have to wait, so let's do a quick test 5887 // first before we take the lock. 5888 if (!free_regions_coming()) { 5889 return; 5890 } 5891 5892 if (G1ConcRegionFreeingVerbose) { 5893 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 5894 "waiting for free regions"); 5895 } 5896 5897 { 5898 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5899 while (free_regions_coming()) { 5900 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 5901 } 5902 } 5903 5904 if (G1ConcRegionFreeingVerbose) { 5905 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 5906 "done waiting for free regions"); 5907 } 5908 } 5909 5910 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 5911 return _allocator->is_retained_old_region(hr); 5912 } 5913 5914 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 5915 _young_list->push_region(hr); 5916 } 5917 5918 class NoYoungRegionsClosure: public HeapRegionClosure { 5919 private: 5920 bool _success; 5921 public: 5922 NoYoungRegionsClosure() : _success(true) { } 5923 bool doHeapRegion(HeapRegion* r) { 5924 if (r->is_young()) { 5925 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 5926 p2i(r->bottom()), p2i(r->end())); 5927 _success = false; 5928 } 5929 return false; 5930 } 5931 bool success() { return _success; } 5932 }; 5933 5934 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 5935 bool ret = _young_list->check_list_empty(check_sample); 5936 5937 if (check_heap) { 5938 NoYoungRegionsClosure closure; 5939 heap_region_iterate(&closure); 5940 ret = ret && closure.success(); 5941 } 5942 5943 return ret; 5944 } 5945 5946 class TearDownRegionSetsClosure : public HeapRegionClosure { 5947 private: 5948 HeapRegionSet *_old_set; 5949 5950 public: 5951 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 5952 5953 bool doHeapRegion(HeapRegion* r) { 5954 if (r->is_old()) { 5955 _old_set->remove(r); 5956 } else { 5957 // We ignore free regions, we'll empty the free list afterwards. 5958 // We ignore young regions, we'll empty the young list afterwards. 5959 // We ignore humongous regions, we're not tearing down the 5960 // humongous regions set. 5961 assert(r->is_free() || r->is_young() || r->is_humongous(), 5962 "it cannot be another type"); 5963 } 5964 return false; 5965 } 5966 5967 ~TearDownRegionSetsClosure() { 5968 assert(_old_set->is_empty(), "post-condition"); 5969 } 5970 }; 5971 5972 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 5973 assert_at_safepoint(true /* should_be_vm_thread */); 5974 5975 if (!free_list_only) { 5976 TearDownRegionSetsClosure cl(&_old_set); 5977 heap_region_iterate(&cl); 5978 5979 // Note that emptying the _young_list is postponed and instead done as 5980 // the first step when rebuilding the regions sets again. The reason for 5981 // this is that during a full GC string deduplication needs to know if 5982 // a collected region was young or old when the full GC was initiated. 5983 } 5984 _hrm.remove_all_free_regions(); 5985 } 5986 5987 void G1CollectedHeap::increase_used(size_t bytes) { 5988 _summary_bytes_used += bytes; 5989 } 5990 5991 void G1CollectedHeap::decrease_used(size_t bytes) { 5992 assert(_summary_bytes_used >= bytes, 5993 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 5994 _summary_bytes_used, bytes); 5995 _summary_bytes_used -= bytes; 5996 } 5997 5998 void G1CollectedHeap::set_used(size_t bytes) { 5999 _summary_bytes_used = bytes; 6000 } 6001 6002 class RebuildRegionSetsClosure : public HeapRegionClosure { 6003 private: 6004 bool _free_list_only; 6005 HeapRegionSet* _old_set; 6006 HeapRegionManager* _hrm; 6007 size_t _total_used; 6008 6009 public: 6010 RebuildRegionSetsClosure(bool free_list_only, 6011 HeapRegionSet* old_set, HeapRegionManager* hrm) : 6012 _free_list_only(free_list_only), 6013 _old_set(old_set), _hrm(hrm), _total_used(0) { 6014 assert(_hrm->num_free_regions() == 0, "pre-condition"); 6015 if (!free_list_only) { 6016 assert(_old_set->is_empty(), "pre-condition"); 6017 } 6018 } 6019 6020 bool doHeapRegion(HeapRegion* r) { 6021 if (r->is_empty()) { 6022 // Add free regions to the free list 6023 r->set_free(); 6024 r->set_allocation_context(AllocationContext::system()); 6025 _hrm->insert_into_free_list(r); 6026 } else if (!_free_list_only) { 6027 assert(!r->is_young(), "we should not come across young regions"); 6028 6029 if (r->is_humongous()) { 6030 // We ignore humongous regions. We left the humongous set unchanged. 6031 } else { 6032 // Objects that were compacted would have ended up on regions 6033 // that were previously old or free. Archive regions (which are 6034 // old) will not have been touched. 6035 assert(r->is_free() || r->is_old(), "invariant"); 6036 // We now consider them old, so register as such. Leave 6037 // archive regions set that way, however, while still adding 6038 // them to the old set. 6039 if (!r->is_archive()) { 6040 r->set_old(); 6041 } 6042 _old_set->add(r); 6043 } 6044 _total_used += r->used(); 6045 } 6046 6047 return false; 6048 } 6049 6050 size_t total_used() { 6051 return _total_used; 6052 } 6053 }; 6054 6055 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6056 assert_at_safepoint(true /* should_be_vm_thread */); 6057 6058 if (!free_list_only) { 6059 _young_list->empty_list(); 6060 } 6061 6062 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 6063 heap_region_iterate(&cl); 6064 6065 if (!free_list_only) { 6066 set_used(cl.total_used()); 6067 if (_archive_allocator != NULL) { 6068 _archive_allocator->clear_used(); 6069 } 6070 } 6071 assert(used_unlocked() == recalculate_used(), 6072 "inconsistent used_unlocked(), " 6073 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 6074 used_unlocked(), recalculate_used()); 6075 } 6076 6077 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6078 _refine_cte_cl->set_concurrent(concurrent); 6079 } 6080 6081 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6082 HeapRegion* hr = heap_region_containing(p); 6083 return hr->is_in(p); 6084 } 6085 6086 // Methods for the mutator alloc region 6087 6088 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6089 bool force) { 6090 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6091 assert(!force || g1_policy()->can_expand_young_list(), 6092 "if force is true we should be able to expand the young list"); 6093 bool young_list_full = g1_policy()->is_young_list_full(); 6094 if (force || !young_list_full) { 6095 HeapRegion* new_alloc_region = new_region(word_size, 6096 false /* is_old */, 6097 false /* do_expand */); 6098 if (new_alloc_region != NULL) { 6099 set_region_short_lived_locked(new_alloc_region); 6100 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6101 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6102 return new_alloc_region; 6103 } 6104 } 6105 return NULL; 6106 } 6107 6108 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6109 size_t allocated_bytes) { 6110 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6111 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 6112 6113 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6114 increase_used(allocated_bytes); 6115 _hr_printer.retire(alloc_region); 6116 // We update the eden sizes here, when the region is retired, 6117 // instead of when it's allocated, since this is the point that its 6118 // used space has been recored in _summary_bytes_used. 6119 g1mm()->update_eden_size(); 6120 } 6121 6122 // Methods for the GC alloc regions 6123 6124 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6125 uint count, 6126 InCSetState dest) { 6127 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6128 6129 if (count < g1_policy()->max_regions(dest)) { 6130 const bool is_survivor = (dest.is_young()); 6131 HeapRegion* new_alloc_region = new_region(word_size, 6132 !is_survivor, 6133 true /* do_expand */); 6134 if (new_alloc_region != NULL) { 6135 // We really only need to do this for old regions given that we 6136 // should never scan survivors. But it doesn't hurt to do it 6137 // for survivors too. 6138 new_alloc_region->record_timestamp(); 6139 if (is_survivor) { 6140 new_alloc_region->set_survivor(); 6141 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6142 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6143 } else { 6144 new_alloc_region->set_old(); 6145 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6146 check_bitmaps("Old Region Allocation", new_alloc_region); 6147 } 6148 bool during_im = collector_state()->during_initial_mark_pause(); 6149 new_alloc_region->note_start_of_copying(during_im); 6150 return new_alloc_region; 6151 } 6152 } 6153 return NULL; 6154 } 6155 6156 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6157 size_t allocated_bytes, 6158 InCSetState dest) { 6159 bool during_im = collector_state()->during_initial_mark_pause(); 6160 alloc_region->note_end_of_copying(during_im); 6161 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6162 if (dest.is_young()) { 6163 young_list()->add_survivor_region(alloc_region); 6164 } else { 6165 _old_set.add(alloc_region); 6166 } 6167 _hr_printer.retire(alloc_region); 6168 } 6169 6170 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 6171 bool expanded = false; 6172 uint index = _hrm.find_highest_free(&expanded); 6173 6174 if (index != G1_NO_HRM_INDEX) { 6175 if (expanded) { 6176 ergo_verbose1(ErgoHeapSizing, 6177 "attempt heap expansion", 6178 ergo_format_reason("requested address range outside heap bounds") 6179 ergo_format_byte("region size"), 6180 HeapRegion::GrainWords * HeapWordSize); 6181 } 6182 _hrm.allocate_free_regions_starting_at(index, 1); 6183 return region_at(index); 6184 } 6185 return NULL; 6186 } 6187 6188 // Heap region set verification 6189 6190 class VerifyRegionListsClosure : public HeapRegionClosure { 6191 private: 6192 HeapRegionSet* _old_set; 6193 HeapRegionSet* _humongous_set; 6194 HeapRegionManager* _hrm; 6195 6196 public: 6197 HeapRegionSetCount _old_count; 6198 HeapRegionSetCount _humongous_count; 6199 HeapRegionSetCount _free_count; 6200 6201 VerifyRegionListsClosure(HeapRegionSet* old_set, 6202 HeapRegionSet* humongous_set, 6203 HeapRegionManager* hrm) : 6204 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm), 6205 _old_count(), _humongous_count(), _free_count(){ } 6206 6207 bool doHeapRegion(HeapRegion* hr) { 6208 if (hr->is_young()) { 6209 // TODO 6210 } else if (hr->is_humongous()) { 6211 assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index()); 6212 _humongous_count.increment(1u, hr->capacity()); 6213 } else if (hr->is_empty()) { 6214 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index()); 6215 _free_count.increment(1u, hr->capacity()); 6216 } else if (hr->is_old()) { 6217 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index()); 6218 _old_count.increment(1u, hr->capacity()); 6219 } else { 6220 // There are no other valid region types. Check for one invalid 6221 // one we can identify: pinned without old or humongous set. 6222 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index()); 6223 ShouldNotReachHere(); 6224 } 6225 return false; 6226 } 6227 6228 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) { 6229 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()); 6230 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6231 old_set->total_capacity_bytes(), _old_count.capacity()); 6232 6233 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()); 6234 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6235 humongous_set->total_capacity_bytes(), _humongous_count.capacity()); 6236 6237 guarantee(free_list->num_free_regions() == _free_count.length(), "Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count.length()); 6238 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6239 free_list->total_capacity_bytes(), _free_count.capacity()); 6240 } 6241 }; 6242 6243 void G1CollectedHeap::verify_region_sets() { 6244 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6245 6246 // First, check the explicit lists. 6247 _hrm.verify(); 6248 { 6249 // Given that a concurrent operation might be adding regions to 6250 // the secondary free list we have to take the lock before 6251 // verifying it. 6252 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6253 _secondary_free_list.verify_list(); 6254 } 6255 6256 // If a concurrent region freeing operation is in progress it will 6257 // be difficult to correctly attributed any free regions we come 6258 // across to the correct free list given that they might belong to 6259 // one of several (free_list, secondary_free_list, any local lists, 6260 // etc.). So, if that's the case we will skip the rest of the 6261 // verification operation. Alternatively, waiting for the concurrent 6262 // operation to complete will have a non-trivial effect on the GC's 6263 // operation (no concurrent operation will last longer than the 6264 // interval between two calls to verification) and it might hide 6265 // any issues that we would like to catch during testing. 6266 if (free_regions_coming()) { 6267 return; 6268 } 6269 6270 // Make sure we append the secondary_free_list on the free_list so 6271 // that all free regions we will come across can be safely 6272 // attributed to the free_list. 6273 append_secondary_free_list_if_not_empty_with_lock(); 6274 6275 // Finally, make sure that the region accounting in the lists is 6276 // consistent with what we see in the heap. 6277 6278 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm); 6279 heap_region_iterate(&cl); 6280 cl.verify_counts(&_old_set, &_humongous_set, &_hrm); 6281 } 6282 6283 // Optimized nmethod scanning 6284 6285 class RegisterNMethodOopClosure: public OopClosure { 6286 G1CollectedHeap* _g1h; 6287 nmethod* _nm; 6288 6289 template <class T> void do_oop_work(T* p) { 6290 T heap_oop = oopDesc::load_heap_oop(p); 6291 if (!oopDesc::is_null(heap_oop)) { 6292 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6293 HeapRegion* hr = _g1h->heap_region_containing(obj); 6294 assert(!hr->is_continues_humongous(), 6295 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 6296 " starting at " HR_FORMAT, 6297 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 6298 6299 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 6300 hr->add_strong_code_root_locked(_nm); 6301 } 6302 } 6303 6304 public: 6305 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6306 _g1h(g1h), _nm(nm) {} 6307 6308 void do_oop(oop* p) { do_oop_work(p); } 6309 void do_oop(narrowOop* p) { do_oop_work(p); } 6310 }; 6311 6312 class UnregisterNMethodOopClosure: public OopClosure { 6313 G1CollectedHeap* _g1h; 6314 nmethod* _nm; 6315 6316 template <class T> void do_oop_work(T* p) { 6317 T heap_oop = oopDesc::load_heap_oop(p); 6318 if (!oopDesc::is_null(heap_oop)) { 6319 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6320 HeapRegion* hr = _g1h->heap_region_containing(obj); 6321 assert(!hr->is_continues_humongous(), 6322 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 6323 " starting at " HR_FORMAT, 6324 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 6325 6326 hr->remove_strong_code_root(_nm); 6327 } 6328 } 6329 6330 public: 6331 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6332 _g1h(g1h), _nm(nm) {} 6333 6334 void do_oop(oop* p) { do_oop_work(p); } 6335 void do_oop(narrowOop* p) { do_oop_work(p); } 6336 }; 6337 6338 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6339 CollectedHeap::register_nmethod(nm); 6340 6341 guarantee(nm != NULL, "sanity"); 6342 RegisterNMethodOopClosure reg_cl(this, nm); 6343 nm->oops_do(®_cl); 6344 } 6345 6346 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6347 CollectedHeap::unregister_nmethod(nm); 6348 6349 guarantee(nm != NULL, "sanity"); 6350 UnregisterNMethodOopClosure reg_cl(this, nm); 6351 nm->oops_do(®_cl, true); 6352 } 6353 6354 void G1CollectedHeap::purge_code_root_memory() { 6355 double purge_start = os::elapsedTime(); 6356 G1CodeRootSet::purge(); 6357 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6358 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6359 } 6360 6361 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6362 G1CollectedHeap* _g1h; 6363 6364 public: 6365 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6366 _g1h(g1h) {} 6367 6368 void do_code_blob(CodeBlob* cb) { 6369 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6370 if (nm == NULL) { 6371 return; 6372 } 6373 6374 if (ScavengeRootsInCode) { 6375 _g1h->register_nmethod(nm); 6376 } 6377 } 6378 }; 6379 6380 void G1CollectedHeap::rebuild_strong_code_roots() { 6381 RebuildStrongCodeRootClosure blob_cl(this); 6382 CodeCache::blobs_do(&blob_cl); 6383 }