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/g1EvacFailure.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_processed; 116 117 public: 118 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { } 119 120 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 121 *card_ptr = CardTableModRefBS::dirty_card_val(); 122 _num_processed++; 123 return true; 124 } 125 126 size_t num_processed() const { return _num_processed; } 127 }; 128 129 130 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 131 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 132 } 133 134 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 135 // The from card cache is not the memory that is actually committed. So we cannot 136 // take advantage of the zero_filled parameter. 137 reset_from_card_cache(start_idx, num_regions); 138 } 139 140 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 141 { 142 // Claim the right to put the region on the dirty cards region list 143 // by installing a self pointer. 144 HeapRegion* next = hr->get_next_dirty_cards_region(); 145 if (next == NULL) { 146 HeapRegion* res = (HeapRegion*) 147 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 148 NULL); 149 if (res == NULL) { 150 HeapRegion* head; 151 do { 152 // Put the region to the dirty cards region list. 153 head = _dirty_cards_region_list; 154 next = (HeapRegion*) 155 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 156 if (next == head) { 157 assert(hr->get_next_dirty_cards_region() == hr, 158 "hr->get_next_dirty_cards_region() != hr"); 159 if (next == NULL) { 160 // The last region in the list points to itself. 161 hr->set_next_dirty_cards_region(hr); 162 } else { 163 hr->set_next_dirty_cards_region(next); 164 } 165 } 166 } while (next != head); 167 } 168 } 169 } 170 171 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 172 { 173 HeapRegion* head; 174 HeapRegion* hr; 175 do { 176 head = _dirty_cards_region_list; 177 if (head == NULL) { 178 return NULL; 179 } 180 HeapRegion* new_head = head->get_next_dirty_cards_region(); 181 if (head == new_head) { 182 // The last region. 183 new_head = NULL; 184 } 185 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 186 head); 187 } while (hr != head); 188 assert(hr != NULL, "invariant"); 189 hr->set_next_dirty_cards_region(NULL); 190 return hr; 191 } 192 193 // Returns true if the reference points to an object that 194 // can move in an incremental collection. 195 bool G1CollectedHeap::is_scavengable(const void* p) { 196 HeapRegion* hr = heap_region_containing(p); 197 return !hr->is_pinned(); 198 } 199 200 // Private methods. 201 202 HeapRegion* 203 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 204 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 205 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 206 if (!_secondary_free_list.is_empty()) { 207 if (G1ConcRegionFreeingVerbose) { 208 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 209 "secondary_free_list has %u entries", 210 _secondary_free_list.length()); 211 } 212 // It looks as if there are free regions available on the 213 // secondary_free_list. Let's move them to the free_list and try 214 // again to allocate from it. 215 append_secondary_free_list(); 216 217 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 218 "empty we should have moved at least one entry to the free_list"); 219 HeapRegion* res = _hrm.allocate_free_region(is_old); 220 if (G1ConcRegionFreeingVerbose) { 221 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 222 "allocated " HR_FORMAT " from secondary_free_list", 223 HR_FORMAT_PARAMS(res)); 224 } 225 return res; 226 } 227 228 // Wait here until we get notified either when (a) there are no 229 // more free regions coming or (b) some regions have been moved on 230 // the secondary_free_list. 231 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 232 } 233 234 if (G1ConcRegionFreeingVerbose) { 235 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 236 "could not allocate from secondary_free_list"); 237 } 238 return NULL; 239 } 240 241 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 242 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 243 "the only time we use this to allocate a humongous region is " 244 "when we are allocating a single humongous region"); 245 246 HeapRegion* res; 247 if (G1StressConcRegionFreeing) { 248 if (!_secondary_free_list.is_empty()) { 249 if (G1ConcRegionFreeingVerbose) { 250 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 251 "forced to look at the secondary_free_list"); 252 } 253 res = new_region_try_secondary_free_list(is_old); 254 if (res != NULL) { 255 return res; 256 } 257 } 258 } 259 260 res = _hrm.allocate_free_region(is_old); 261 262 if (res == NULL) { 263 if (G1ConcRegionFreeingVerbose) { 264 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 265 "res == NULL, trying the secondary_free_list"); 266 } 267 res = new_region_try_secondary_free_list(is_old); 268 } 269 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 270 // Currently, only attempts to allocate GC alloc regions set 271 // do_expand to true. So, we should only reach here during a 272 // safepoint. If this assumption changes we might have to 273 // reconsider the use of _expand_heap_after_alloc_failure. 274 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 275 276 ergo_verbose1(ErgoHeapSizing, 277 "attempt heap expansion", 278 ergo_format_reason("region allocation request failed") 279 ergo_format_byte("allocation request"), 280 word_size * HeapWordSize); 281 if (expand(word_size * HeapWordSize)) { 282 // Given that expand() succeeded in expanding the heap, and we 283 // always expand the heap by an amount aligned to the heap 284 // region size, the free list should in theory not be empty. 285 // In either case allocate_free_region() will check for NULL. 286 res = _hrm.allocate_free_region(is_old); 287 } else { 288 _expand_heap_after_alloc_failure = false; 289 } 290 } 291 return res; 292 } 293 294 HeapWord* 295 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 296 uint num_regions, 297 size_t word_size, 298 AllocationContext_t context) { 299 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 300 assert(is_humongous(word_size), "word_size should be humongous"); 301 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 302 303 // Index of last region in the series + 1. 304 uint last = first + num_regions; 305 306 // We need to initialize the region(s) we just discovered. This is 307 // a bit tricky given that it can happen concurrently with 308 // refinement threads refining cards on these regions and 309 // potentially wanting to refine the BOT as they are scanning 310 // those cards (this can happen shortly after a cleanup; see CR 311 // 6991377). So we have to set up the region(s) carefully and in 312 // a specific order. 313 314 // The word size sum of all the regions we will allocate. 315 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 316 assert(word_size <= word_size_sum, "sanity"); 317 318 // This will be the "starts humongous" region. 319 HeapRegion* first_hr = region_at(first); 320 // The header of the new object will be placed at the bottom of 321 // the first region. 322 HeapWord* new_obj = first_hr->bottom(); 323 // This will be the new end of the first region in the series that 324 // should also match the end of the last region in the series. 325 HeapWord* new_end = new_obj + word_size_sum; 326 // This will be the new top of the first region that will reflect 327 // this allocation. 328 HeapWord* new_top = new_obj + word_size; 329 330 // First, we need to zero the header of the space that we will be 331 // allocating. When we update top further down, some refinement 332 // threads might try to scan the region. By zeroing the header we 333 // ensure that any thread that will try to scan the region will 334 // come across the zero klass word and bail out. 335 // 336 // NOTE: It would not have been correct to have used 337 // CollectedHeap::fill_with_object() and make the space look like 338 // an int array. The thread that is doing the allocation will 339 // later update the object header to a potentially different array 340 // type and, for a very short period of time, the klass and length 341 // fields will be inconsistent. This could cause a refinement 342 // thread to calculate the object size incorrectly. 343 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 344 345 // We will set up the first region as "starts humongous". This 346 // will also update the BOT covering all the regions to reflect 347 // that there is a single object that starts at the bottom of the 348 // first region. 349 first_hr->set_starts_humongous(new_top, new_end); 350 first_hr->set_allocation_context(context); 351 // Then, if there are any, we will set up the "continues 352 // humongous" regions. 353 HeapRegion* hr = NULL; 354 for (uint i = first + 1; i < last; ++i) { 355 hr = region_at(i); 356 hr->set_continues_humongous(first_hr); 357 hr->set_allocation_context(context); 358 } 359 // If we have "continues humongous" regions (hr != NULL), then the 360 // end of the last one should match new_end. 361 assert(hr == NULL || hr->end() == new_end, "sanity"); 362 363 // Up to this point no concurrent thread would have been able to 364 // do any scanning on any region in this series. All the top 365 // fields still point to bottom, so the intersection between 366 // [bottom,top] and [card_start,card_end] will be empty. Before we 367 // update the top fields, we'll do a storestore to make sure that 368 // no thread sees the update to top before the zeroing of the 369 // object header and the BOT initialization. 370 OrderAccess::storestore(); 371 372 // Now that the BOT and the object header have been initialized, 373 // we can update top of the "starts humongous" region. 374 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 375 "new_top should be in this region"); 376 first_hr->set_top(new_top); 377 if (_hr_printer.is_active()) { 378 HeapWord* bottom = first_hr->bottom(); 379 HeapWord* end = first_hr->orig_end(); 380 if ((first + 1) == last) { 381 // the series has a single humongous region 382 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 383 } else { 384 // the series has more than one humongous regions 385 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 386 } 387 } 388 389 // Now, we will update the top fields of the "continues humongous" 390 // regions. The reason we need to do this is that, otherwise, 391 // these regions would look empty and this will confuse parts of 392 // G1. For example, the code that looks for a consecutive number 393 // of empty regions will consider them empty and try to 394 // re-allocate them. We can extend is_empty() to also include 395 // !is_continues_humongous(), but it is easier to just update the top 396 // fields here. The way we set top for all regions (i.e., top == 397 // end for all regions but the last one, top == new_top for the 398 // last one) is actually used when we will free up the humongous 399 // region in free_humongous_region(). 400 hr = NULL; 401 for (uint i = first + 1; i < last; ++i) { 402 hr = region_at(i); 403 if ((i + 1) == last) { 404 // last continues humongous region 405 assert(hr->bottom() < new_top && new_top <= hr->end(), 406 "new_top should fall on this region"); 407 hr->set_top(new_top); 408 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 409 } else { 410 // not last one 411 assert(new_top > hr->end(), "new_top should be above this region"); 412 hr->set_top(hr->end()); 413 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 414 } 415 } 416 // If we have continues humongous regions (hr != NULL), then the 417 // end of the last one should match new_end and its top should 418 // match new_top. 419 assert(hr == NULL || 420 (hr->end() == new_end && hr->top() == new_top), "sanity"); 421 check_bitmaps("Humongous Region Allocation", first_hr); 422 423 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 424 increase_used(first_hr->used()); 425 _humongous_set.add(first_hr); 426 427 return new_obj; 428 } 429 430 // If could fit into free regions w/o expansion, try. 431 // Otherwise, if can expand, do so. 432 // Otherwise, if using ex regions might help, try with ex given back. 433 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 434 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 435 436 verify_region_sets_optional(); 437 438 uint first = G1_NO_HRM_INDEX; 439 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords); 440 441 if (obj_regions == 1) { 442 // Only one region to allocate, try to use a fast path by directly allocating 443 // from the free lists. Do not try to expand here, we will potentially do that 444 // later. 445 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 446 if (hr != NULL) { 447 first = hr->hrm_index(); 448 } 449 } else { 450 // We can't allocate humongous regions spanning more than one region while 451 // cleanupComplete() is running, since some of the regions we find to be 452 // empty might not yet be added to the free list. It is not straightforward 453 // to know in which list they are on so that we can remove them. We only 454 // need to do this if we need to allocate more than one region to satisfy the 455 // current humongous allocation request. If we are only allocating one region 456 // we use the one-region region allocation code (see above), that already 457 // potentially waits for regions from the secondary free list. 458 wait_while_free_regions_coming(); 459 append_secondary_free_list_if_not_empty_with_lock(); 460 461 // Policy: Try only empty regions (i.e. already committed first). Maybe we 462 // are lucky enough to find some. 463 first = _hrm.find_contiguous_only_empty(obj_regions); 464 if (first != G1_NO_HRM_INDEX) { 465 _hrm.allocate_free_regions_starting_at(first, obj_regions); 466 } 467 } 468 469 if (first == G1_NO_HRM_INDEX) { 470 // Policy: We could not find enough regions for the humongous object in the 471 // free list. Look through the heap to find a mix of free and uncommitted regions. 472 // If so, try expansion. 473 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 474 if (first != G1_NO_HRM_INDEX) { 475 // We found something. Make sure these regions are committed, i.e. expand 476 // the heap. Alternatively we could do a defragmentation GC. 477 ergo_verbose1(ErgoHeapSizing, 478 "attempt heap expansion", 479 ergo_format_reason("humongous allocation request failed") 480 ergo_format_byte("allocation request"), 481 word_size * HeapWordSize); 482 483 _hrm.expand_at(first, obj_regions); 484 g1_policy()->record_new_heap_size(num_regions()); 485 486 #ifdef ASSERT 487 for (uint i = first; i < first + obj_regions; ++i) { 488 HeapRegion* hr = region_at(i); 489 assert(hr->is_free(), "sanity"); 490 assert(hr->is_empty(), "sanity"); 491 assert(is_on_master_free_list(hr), "sanity"); 492 } 493 #endif 494 _hrm.allocate_free_regions_starting_at(first, obj_regions); 495 } else { 496 // Policy: Potentially trigger a defragmentation GC. 497 } 498 } 499 500 HeapWord* result = NULL; 501 if (first != G1_NO_HRM_INDEX) { 502 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 503 word_size, context); 504 assert(result != NULL, "it should always return a valid result"); 505 506 // A successful humongous object allocation changes the used space 507 // information of the old generation so we need to recalculate the 508 // sizes and update the jstat counters here. 509 g1mm()->update_sizes(); 510 } 511 512 verify_region_sets_optional(); 513 514 return result; 515 } 516 517 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 518 assert_heap_not_locked_and_not_at_safepoint(); 519 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 520 521 uint dummy_gc_count_before; 522 uint dummy_gclocker_retry_count = 0; 523 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 524 } 525 526 HeapWord* 527 G1CollectedHeap::mem_allocate(size_t word_size, 528 bool* gc_overhead_limit_was_exceeded) { 529 assert_heap_not_locked_and_not_at_safepoint(); 530 531 // Loop until the allocation is satisfied, or unsatisfied after GC. 532 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 533 uint gc_count_before; 534 535 HeapWord* result = NULL; 536 if (!is_humongous(word_size)) { 537 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 538 } else { 539 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 540 } 541 if (result != NULL) { 542 return result; 543 } 544 545 // Create the garbage collection operation... 546 VM_G1CollectForAllocation op(gc_count_before, word_size); 547 op.set_allocation_context(AllocationContext::current()); 548 549 // ...and get the VM thread to execute it. 550 VMThread::execute(&op); 551 552 if (op.prologue_succeeded() && op.pause_succeeded()) { 553 // If the operation was successful we'll return the result even 554 // if it is NULL. If the allocation attempt failed immediately 555 // after a Full GC, it's unlikely we'll be able to allocate now. 556 HeapWord* result = op.result(); 557 if (result != NULL && !is_humongous(word_size)) { 558 // Allocations that take place on VM operations do not do any 559 // card dirtying and we have to do it here. We only have to do 560 // this for non-humongous allocations, though. 561 dirty_young_block(result, word_size); 562 } 563 return result; 564 } else { 565 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 566 return NULL; 567 } 568 assert(op.result() == NULL, 569 "the result should be NULL if the VM op did not succeed"); 570 } 571 572 // Give a warning if we seem to be looping forever. 573 if ((QueuedAllocationWarningCount > 0) && 574 (try_count % QueuedAllocationWarningCount == 0)) { 575 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 576 } 577 } 578 579 ShouldNotReachHere(); 580 return NULL; 581 } 582 583 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 584 AllocationContext_t context, 585 uint* gc_count_before_ret, 586 uint* gclocker_retry_count_ret) { 587 // Make sure you read the note in attempt_allocation_humongous(). 588 589 assert_heap_not_locked_and_not_at_safepoint(); 590 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 591 "be called for humongous allocation requests"); 592 593 // We should only get here after the first-level allocation attempt 594 // (attempt_allocation()) failed to allocate. 595 596 // We will loop until a) we manage to successfully perform the 597 // allocation or b) we successfully schedule a collection which 598 // fails to perform the allocation. b) is the only case when we'll 599 // return NULL. 600 HeapWord* result = NULL; 601 for (int try_count = 1; /* we'll return */; try_count += 1) { 602 bool should_try_gc; 603 uint gc_count_before; 604 605 { 606 MutexLockerEx x(Heap_lock); 607 result = _allocator->attempt_allocation_locked(word_size, context); 608 if (result != NULL) { 609 return result; 610 } 611 612 if (GC_locker::is_active_and_needs_gc()) { 613 if (g1_policy()->can_expand_young_list()) { 614 // No need for an ergo verbose message here, 615 // can_expand_young_list() does this when it returns true. 616 result = _allocator->attempt_allocation_force(word_size, context); 617 if (result != NULL) { 618 return result; 619 } 620 } 621 should_try_gc = false; 622 } else { 623 // The GCLocker may not be active but the GCLocker initiated 624 // GC may not yet have been performed (GCLocker::needs_gc() 625 // returns true). In this case we do not try this GC and 626 // wait until the GCLocker initiated GC is performed, and 627 // then retry the allocation. 628 if (GC_locker::needs_gc()) { 629 should_try_gc = false; 630 } else { 631 // Read the GC count while still holding the Heap_lock. 632 gc_count_before = total_collections(); 633 should_try_gc = true; 634 } 635 } 636 } 637 638 if (should_try_gc) { 639 bool succeeded; 640 result = do_collection_pause(word_size, gc_count_before, &succeeded, 641 GCCause::_g1_inc_collection_pause); 642 if (result != NULL) { 643 assert(succeeded, "only way to get back a non-NULL result"); 644 return result; 645 } 646 647 if (succeeded) { 648 // If we get here we successfully scheduled a collection which 649 // failed to allocate. No point in trying to allocate 650 // further. We'll just return NULL. 651 MutexLockerEx x(Heap_lock); 652 *gc_count_before_ret = total_collections(); 653 return NULL; 654 } 655 } else { 656 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 657 MutexLockerEx x(Heap_lock); 658 *gc_count_before_ret = total_collections(); 659 return NULL; 660 } 661 // The GCLocker is either active or the GCLocker initiated 662 // GC has not yet been performed. Stall until it is and 663 // then retry the allocation. 664 GC_locker::stall_until_clear(); 665 (*gclocker_retry_count_ret) += 1; 666 } 667 668 // We can reach here if we were unsuccessful in scheduling a 669 // collection (because another thread beat us to it) or if we were 670 // stalled due to the GC locker. In either can we should retry the 671 // allocation attempt in case another thread successfully 672 // performed a collection and reclaimed enough space. We do the 673 // first attempt (without holding the Heap_lock) here and the 674 // follow-on attempt will be at the start of the next loop 675 // iteration (after taking the Heap_lock). 676 result = _allocator->attempt_allocation(word_size, context); 677 if (result != NULL) { 678 return result; 679 } 680 681 // Give a warning if we seem to be looping forever. 682 if ((QueuedAllocationWarningCount > 0) && 683 (try_count % QueuedAllocationWarningCount == 0)) { 684 warning("G1CollectedHeap::attempt_allocation_slow() " 685 "retries %d times", try_count); 686 } 687 } 688 689 ShouldNotReachHere(); 690 return NULL; 691 } 692 693 void G1CollectedHeap::begin_archive_alloc_range() { 694 assert_at_safepoint(true /* should_be_vm_thread */); 695 if (_archive_allocator == NULL) { 696 _archive_allocator = G1ArchiveAllocator::create_allocator(this); 697 } 698 } 699 700 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 701 // Allocations in archive regions cannot be of a size that would be considered 702 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 703 // may be different at archive-restore time. 704 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 705 } 706 707 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 708 assert_at_safepoint(true /* should_be_vm_thread */); 709 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 710 if (is_archive_alloc_too_large(word_size)) { 711 return NULL; 712 } 713 return _archive_allocator->archive_mem_allocate(word_size); 714 } 715 716 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 717 size_t end_alignment_in_bytes) { 718 assert_at_safepoint(true /* should_be_vm_thread */); 719 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 720 721 // Call complete_archive to do the real work, filling in the MemRegion 722 // array with the archive regions. 723 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 724 delete _archive_allocator; 725 _archive_allocator = NULL; 726 } 727 728 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 729 assert(ranges != NULL, "MemRegion array NULL"); 730 assert(count != 0, "No MemRegions provided"); 731 MemRegion reserved = _hrm.reserved(); 732 for (size_t i = 0; i < count; i++) { 733 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 734 return false; 735 } 736 } 737 return true; 738 } 739 740 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) { 741 assert(!is_init_completed(), "Expect to be called at JVM init time"); 742 assert(ranges != NULL, "MemRegion array NULL"); 743 assert(count != 0, "No MemRegions provided"); 744 MutexLockerEx x(Heap_lock); 745 746 MemRegion reserved = _hrm.reserved(); 747 HeapWord* prev_last_addr = NULL; 748 HeapRegion* prev_last_region = NULL; 749 750 // Temporarily disable pretouching of heap pages. This interface is used 751 // when mmap'ing archived heap data in, so pre-touching is wasted. 752 FlagSetting fs(AlwaysPreTouch, false); 753 754 // Enable archive object checking in G1MarkSweep. We have to let it know 755 // about each archive range, so that objects in those ranges aren't marked. 756 G1MarkSweep::enable_archive_object_check(); 757 758 // For each specified MemRegion range, allocate the corresponding G1 759 // regions and mark them as archive regions. We expect the ranges in 760 // ascending starting address order, without overlap. 761 for (size_t i = 0; i < count; i++) { 762 MemRegion curr_range = ranges[i]; 763 HeapWord* start_address = curr_range.start(); 764 size_t word_size = curr_range.word_size(); 765 HeapWord* last_address = curr_range.last(); 766 size_t commits = 0; 767 768 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 769 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 770 p2i(start_address), p2i(last_address)); 771 guarantee(start_address > prev_last_addr, 772 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 773 p2i(start_address), p2i(prev_last_addr)); 774 prev_last_addr = last_address; 775 776 // Check for ranges that start in the same G1 region in which the previous 777 // range ended, and adjust the start address so we don't try to allocate 778 // the same region again. If the current range is entirely within that 779 // region, skip it, just adjusting the recorded top. 780 HeapRegion* start_region = _hrm.addr_to_region(start_address); 781 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 782 start_address = start_region->end(); 783 if (start_address > last_address) { 784 increase_used(word_size * HeapWordSize); 785 start_region->set_top(last_address + 1); 786 continue; 787 } 788 start_region->set_top(start_address); 789 curr_range = MemRegion(start_address, last_address + 1); 790 start_region = _hrm.addr_to_region(start_address); 791 } 792 793 // Perform the actual region allocation, exiting if it fails. 794 // Then note how much new space we have allocated. 795 if (!_hrm.allocate_containing_regions(curr_range, &commits)) { 796 return false; 797 } 798 increase_used(word_size * HeapWordSize); 799 if (commits != 0) { 800 ergo_verbose1(ErgoHeapSizing, 801 "attempt heap expansion", 802 ergo_format_reason("allocate archive regions") 803 ergo_format_byte("total size"), 804 HeapRegion::GrainWords * HeapWordSize * commits); 805 } 806 807 // Mark each G1 region touched by the range as archive, add it to the old set, 808 // and set the allocation context and top. 809 HeapRegion* curr_region = _hrm.addr_to_region(start_address); 810 HeapRegion* last_region = _hrm.addr_to_region(last_address); 811 prev_last_region = last_region; 812 813 while (curr_region != NULL) { 814 assert(curr_region->is_empty() && !curr_region->is_pinned(), 815 "Region already in use (index %u)", curr_region->hrm_index()); 816 _hr_printer.alloc(curr_region, G1HRPrinter::Archive); 817 curr_region->set_allocation_context(AllocationContext::system()); 818 curr_region->set_archive(); 819 _old_set.add(curr_region); 820 if (curr_region != last_region) { 821 curr_region->set_top(curr_region->end()); 822 curr_region = _hrm.next_region_in_heap(curr_region); 823 } else { 824 curr_region->set_top(last_address + 1); 825 curr_region = NULL; 826 } 827 } 828 829 // Notify mark-sweep of the archive range. 830 G1MarkSweep::set_range_archive(curr_range, true); 831 } 832 return true; 833 } 834 835 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 836 assert(!is_init_completed(), "Expect to be called at JVM init time"); 837 assert(ranges != NULL, "MemRegion array NULL"); 838 assert(count != 0, "No MemRegions provided"); 839 MemRegion reserved = _hrm.reserved(); 840 HeapWord *prev_last_addr = NULL; 841 HeapRegion* prev_last_region = NULL; 842 843 // For each MemRegion, create filler objects, if needed, in the G1 regions 844 // that contain the address range. The address range actually within the 845 // MemRegion will not be modified. That is assumed to have been initialized 846 // elsewhere, probably via an mmap of archived heap data. 847 MutexLockerEx x(Heap_lock); 848 for (size_t i = 0; i < count; i++) { 849 HeapWord* start_address = ranges[i].start(); 850 HeapWord* last_address = ranges[i].last(); 851 852 assert(reserved.contains(start_address) && reserved.contains(last_address), 853 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 854 p2i(start_address), p2i(last_address)); 855 assert(start_address > prev_last_addr, 856 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 857 p2i(start_address), p2i(prev_last_addr)); 858 859 HeapRegion* start_region = _hrm.addr_to_region(start_address); 860 HeapRegion* last_region = _hrm.addr_to_region(last_address); 861 HeapWord* bottom_address = start_region->bottom(); 862 863 // Check for a range beginning in the same region in which the 864 // previous one ended. 865 if (start_region == prev_last_region) { 866 bottom_address = prev_last_addr + 1; 867 } 868 869 // Verify that the regions were all marked as archive regions by 870 // alloc_archive_regions. 871 HeapRegion* curr_region = start_region; 872 while (curr_region != NULL) { 873 guarantee(curr_region->is_archive(), 874 "Expected archive region at index %u", curr_region->hrm_index()); 875 if (curr_region != last_region) { 876 curr_region = _hrm.next_region_in_heap(curr_region); 877 } else { 878 curr_region = NULL; 879 } 880 } 881 882 prev_last_addr = last_address; 883 prev_last_region = last_region; 884 885 // Fill the memory below the allocated range with dummy object(s), 886 // if the region bottom does not match the range start, or if the previous 887 // range ended within the same G1 region, and there is a gap. 888 if (start_address != bottom_address) { 889 size_t fill_size = pointer_delta(start_address, bottom_address); 890 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 891 increase_used(fill_size * HeapWordSize); 892 } 893 } 894 } 895 896 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size, 897 uint* gc_count_before_ret, 898 uint* gclocker_retry_count_ret) { 899 assert_heap_not_locked_and_not_at_safepoint(); 900 assert(!is_humongous(word_size), "attempt_allocation() should not " 901 "be called for humongous allocation requests"); 902 903 AllocationContext_t context = AllocationContext::current(); 904 HeapWord* result = _allocator->attempt_allocation(word_size, context); 905 906 if (result == NULL) { 907 result = attempt_allocation_slow(word_size, 908 context, 909 gc_count_before_ret, 910 gclocker_retry_count_ret); 911 } 912 assert_heap_not_locked(); 913 if (result != NULL) { 914 dirty_young_block(result, word_size); 915 } 916 return result; 917 } 918 919 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 920 assert(!is_init_completed(), "Expect to be called at JVM init time"); 921 assert(ranges != NULL, "MemRegion array NULL"); 922 assert(count != 0, "No MemRegions provided"); 923 MemRegion reserved = _hrm.reserved(); 924 HeapWord* prev_last_addr = NULL; 925 HeapRegion* prev_last_region = NULL; 926 size_t size_used = 0; 927 size_t uncommitted_regions = 0; 928 929 // For each Memregion, free the G1 regions that constitute it, and 930 // notify mark-sweep that the range is no longer to be considered 'archive.' 931 MutexLockerEx x(Heap_lock); 932 for (size_t i = 0; i < count; i++) { 933 HeapWord* start_address = ranges[i].start(); 934 HeapWord* last_address = ranges[i].last(); 935 936 assert(reserved.contains(start_address) && reserved.contains(last_address), 937 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 938 p2i(start_address), p2i(last_address)); 939 assert(start_address > prev_last_addr, 940 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 941 p2i(start_address), p2i(prev_last_addr)); 942 size_used += ranges[i].byte_size(); 943 prev_last_addr = last_address; 944 945 HeapRegion* start_region = _hrm.addr_to_region(start_address); 946 HeapRegion* last_region = _hrm.addr_to_region(last_address); 947 948 // Check for ranges that start in the same G1 region in which the previous 949 // range ended, and adjust the start address so we don't try to free 950 // the same region again. If the current range is entirely within that 951 // region, skip it. 952 if (start_region == prev_last_region) { 953 start_address = start_region->end(); 954 if (start_address > last_address) { 955 continue; 956 } 957 start_region = _hrm.addr_to_region(start_address); 958 } 959 prev_last_region = last_region; 960 961 // After verifying that each region was marked as an archive region by 962 // alloc_archive_regions, set it free and empty and uncommit it. 963 HeapRegion* curr_region = start_region; 964 while (curr_region != NULL) { 965 guarantee(curr_region->is_archive(), 966 "Expected archive region at index %u", curr_region->hrm_index()); 967 uint curr_index = curr_region->hrm_index(); 968 _old_set.remove(curr_region); 969 curr_region->set_free(); 970 curr_region->set_top(curr_region->bottom()); 971 if (curr_region != last_region) { 972 curr_region = _hrm.next_region_in_heap(curr_region); 973 } else { 974 curr_region = NULL; 975 } 976 _hrm.shrink_at(curr_index, 1); 977 uncommitted_regions++; 978 } 979 980 // Notify mark-sweep that this is no longer an archive range. 981 G1MarkSweep::set_range_archive(ranges[i], false); 982 } 983 984 if (uncommitted_regions != 0) { 985 ergo_verbose1(ErgoHeapSizing, 986 "attempt heap shrinking", 987 ergo_format_reason("uncommitted archive regions") 988 ergo_format_byte("total size"), 989 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 990 } 991 decrease_used(size_used); 992 } 993 994 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 995 uint* gc_count_before_ret, 996 uint* gclocker_retry_count_ret) { 997 // The structure of this method has a lot of similarities to 998 // attempt_allocation_slow(). The reason these two were not merged 999 // into a single one is that such a method would require several "if 1000 // allocation is not humongous do this, otherwise do that" 1001 // conditional paths which would obscure its flow. In fact, an early 1002 // version of this code did use a unified method which was harder to 1003 // follow and, as a result, it had subtle bugs that were hard to 1004 // track down. So keeping these two methods separate allows each to 1005 // be more readable. It will be good to keep these two in sync as 1006 // much as possible. 1007 1008 assert_heap_not_locked_and_not_at_safepoint(); 1009 assert(is_humongous(word_size), "attempt_allocation_humongous() " 1010 "should only be called for humongous allocations"); 1011 1012 // Humongous objects can exhaust the heap quickly, so we should check if we 1013 // need to start a marking cycle at each humongous object allocation. We do 1014 // the check before we do the actual allocation. The reason for doing it 1015 // before the allocation is that we avoid having to keep track of the newly 1016 // allocated memory while we do a GC. 1017 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1018 word_size)) { 1019 collect(GCCause::_g1_humongous_allocation); 1020 } 1021 1022 // We will loop until a) we manage to successfully perform the 1023 // allocation or b) we successfully schedule a collection which 1024 // fails to perform the allocation. b) is the only case when we'll 1025 // return NULL. 1026 HeapWord* result = NULL; 1027 for (int try_count = 1; /* we'll return */; try_count += 1) { 1028 bool should_try_gc; 1029 uint gc_count_before; 1030 1031 { 1032 MutexLockerEx x(Heap_lock); 1033 1034 // Given that humongous objects are not allocated in young 1035 // regions, we'll first try to do the allocation without doing a 1036 // collection hoping that there's enough space in the heap. 1037 result = humongous_obj_allocate(word_size, AllocationContext::current()); 1038 if (result != NULL) { 1039 return result; 1040 } 1041 1042 if (GC_locker::is_active_and_needs_gc()) { 1043 should_try_gc = false; 1044 } else { 1045 // The GCLocker may not be active but the GCLocker initiated 1046 // GC may not yet have been performed (GCLocker::needs_gc() 1047 // returns true). In this case we do not try this GC and 1048 // wait until the GCLocker initiated GC is performed, and 1049 // then retry the allocation. 1050 if (GC_locker::needs_gc()) { 1051 should_try_gc = false; 1052 } else { 1053 // Read the GC count while still holding the Heap_lock. 1054 gc_count_before = total_collections(); 1055 should_try_gc = true; 1056 } 1057 } 1058 } 1059 1060 if (should_try_gc) { 1061 // If we failed to allocate the humongous object, we should try to 1062 // do a collection pause (if we're allowed) in case it reclaims 1063 // enough space for the allocation to succeed after the pause. 1064 1065 bool succeeded; 1066 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1067 GCCause::_g1_humongous_allocation); 1068 if (result != NULL) { 1069 assert(succeeded, "only way to get back a non-NULL result"); 1070 return result; 1071 } 1072 1073 if (succeeded) { 1074 // If we get here we successfully scheduled a collection which 1075 // failed to allocate. No point in trying to allocate 1076 // further. We'll just return NULL. 1077 MutexLockerEx x(Heap_lock); 1078 *gc_count_before_ret = total_collections(); 1079 return NULL; 1080 } 1081 } else { 1082 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1083 MutexLockerEx x(Heap_lock); 1084 *gc_count_before_ret = total_collections(); 1085 return NULL; 1086 } 1087 // The GCLocker is either active or the GCLocker initiated 1088 // GC has not yet been performed. Stall until it is and 1089 // then retry the allocation. 1090 GC_locker::stall_until_clear(); 1091 (*gclocker_retry_count_ret) += 1; 1092 } 1093 1094 // We can reach here if we were unsuccessful in scheduling a 1095 // collection (because another thread beat us to it) or if we were 1096 // stalled due to the GC locker. In either can we should retry the 1097 // allocation attempt in case another thread successfully 1098 // performed a collection and reclaimed enough space. Give a 1099 // warning if we seem to be looping forever. 1100 1101 if ((QueuedAllocationWarningCount > 0) && 1102 (try_count % QueuedAllocationWarningCount == 0)) { 1103 warning("G1CollectedHeap::attempt_allocation_humongous() " 1104 "retries %d times", try_count); 1105 } 1106 } 1107 1108 ShouldNotReachHere(); 1109 return NULL; 1110 } 1111 1112 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1113 AllocationContext_t context, 1114 bool expect_null_mutator_alloc_region) { 1115 assert_at_safepoint(true /* should_be_vm_thread */); 1116 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region, 1117 "the current alloc region was unexpectedly found to be non-NULL"); 1118 1119 if (!is_humongous(word_size)) { 1120 return _allocator->attempt_allocation_locked(word_size, context); 1121 } else { 1122 HeapWord* result = humongous_obj_allocate(word_size, context); 1123 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1124 collector_state()->set_initiate_conc_mark_if_possible(true); 1125 } 1126 return result; 1127 } 1128 1129 ShouldNotReachHere(); 1130 } 1131 1132 class PostMCRemSetClearClosure: public HeapRegionClosure { 1133 G1CollectedHeap* _g1h; 1134 ModRefBarrierSet* _mr_bs; 1135 public: 1136 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1137 _g1h(g1h), _mr_bs(mr_bs) {} 1138 1139 bool doHeapRegion(HeapRegion* r) { 1140 HeapRegionRemSet* hrrs = r->rem_set(); 1141 1142 if (r->is_continues_humongous()) { 1143 // We'll assert that the strong code root list and RSet is empty 1144 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1145 assert(hrrs->occupied() == 0, "RSet should be empty"); 1146 return false; 1147 } 1148 1149 _g1h->reset_gc_time_stamps(r); 1150 hrrs->clear(); 1151 // You might think here that we could clear just the cards 1152 // corresponding to the used region. But no: if we leave a dirty card 1153 // in a region we might allocate into, then it would prevent that card 1154 // from being enqueued, and cause it to be missed. 1155 // Re: the performance cost: we shouldn't be doing full GC anyway! 1156 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1157 1158 return false; 1159 } 1160 }; 1161 1162 void G1CollectedHeap::clear_rsets_post_compaction() { 1163 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1164 heap_region_iterate(&rs_clear); 1165 } 1166 1167 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1168 G1CollectedHeap* _g1h; 1169 UpdateRSOopClosure _cl; 1170 public: 1171 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) : 1172 _cl(g1->g1_rem_set(), worker_i), 1173 _g1h(g1) 1174 { } 1175 1176 bool doHeapRegion(HeapRegion* r) { 1177 if (!r->is_continues_humongous()) { 1178 _cl.set_from(r); 1179 r->oop_iterate(&_cl); 1180 } 1181 return false; 1182 } 1183 }; 1184 1185 class ParRebuildRSTask: public AbstractGangTask { 1186 G1CollectedHeap* _g1; 1187 HeapRegionClaimer _hrclaimer; 1188 1189 public: 1190 ParRebuildRSTask(G1CollectedHeap* g1) : 1191 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {} 1192 1193 void work(uint worker_id) { 1194 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1195 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer); 1196 } 1197 }; 1198 1199 class PostCompactionPrinterClosure: public HeapRegionClosure { 1200 private: 1201 G1HRPrinter* _hr_printer; 1202 public: 1203 bool doHeapRegion(HeapRegion* hr) { 1204 assert(!hr->is_young(), "not expecting to find young regions"); 1205 if (hr->is_free()) { 1206 // We only generate output for non-empty regions. 1207 } else if (hr->is_starts_humongous()) { 1208 if (hr->region_num() == 1) { 1209 // single humongous region 1210 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1211 } else { 1212 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1213 } 1214 } else if (hr->is_continues_humongous()) { 1215 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1216 } else if (hr->is_archive()) { 1217 _hr_printer->post_compaction(hr, G1HRPrinter::Archive); 1218 } else if (hr->is_old()) { 1219 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1220 } else { 1221 ShouldNotReachHere(); 1222 } 1223 return false; 1224 } 1225 1226 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1227 : _hr_printer(hr_printer) { } 1228 }; 1229 1230 void G1CollectedHeap::print_hrm_post_compaction() { 1231 PostCompactionPrinterClosure cl(hr_printer()); 1232 heap_region_iterate(&cl); 1233 } 1234 1235 bool G1CollectedHeap::do_collection(bool explicit_gc, 1236 bool clear_all_soft_refs, 1237 size_t word_size) { 1238 assert_at_safepoint(true /* should_be_vm_thread */); 1239 1240 if (GC_locker::check_active_before_gc()) { 1241 return false; 1242 } 1243 1244 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1245 gc_timer->register_gc_start(); 1246 1247 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1248 GCIdMark gc_id_mark; 1249 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1250 1251 SvcGCMarker sgcm(SvcGCMarker::FULL); 1252 ResourceMark rm; 1253 1254 G1Log::update_level(); 1255 print_heap_before_gc(); 1256 trace_heap_before_gc(gc_tracer); 1257 1258 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1259 1260 verify_region_sets_optional(); 1261 1262 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1263 collector_policy()->should_clear_all_soft_refs(); 1264 1265 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1266 1267 { 1268 IsGCActiveMark x; 1269 1270 // Timing 1271 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1272 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1273 1274 { 1275 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL); 1276 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1277 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1278 1279 g1_policy()->record_full_collection_start(); 1280 1281 // Note: When we have a more flexible GC logging framework that 1282 // allows us to add optional attributes to a GC log record we 1283 // could consider timing and reporting how long we wait in the 1284 // following two methods. 1285 wait_while_free_regions_coming(); 1286 // If we start the compaction before the CM threads finish 1287 // scanning the root regions we might trip them over as we'll 1288 // be moving objects / updating references. So let's wait until 1289 // they are done. By telling them to abort, they should complete 1290 // early. 1291 _cm->root_regions()->abort(); 1292 _cm->root_regions()->wait_until_scan_finished(); 1293 append_secondary_free_list_if_not_empty_with_lock(); 1294 1295 gc_prologue(true); 1296 increment_total_collections(true /* full gc */); 1297 increment_old_marking_cycles_started(); 1298 1299 assert(used() == recalculate_used(), "Should be equal"); 1300 1301 verify_before_gc(); 1302 1303 check_bitmaps("Full GC Start"); 1304 pre_full_gc_dump(gc_timer); 1305 1306 #if defined(COMPILER2) || INCLUDE_JVMCI 1307 DerivedPointerTable::clear(); 1308 #endif 1309 1310 // Disable discovery and empty the discovered lists 1311 // for the CM ref processor. 1312 ref_processor_cm()->disable_discovery(); 1313 ref_processor_cm()->abandon_partial_discovery(); 1314 ref_processor_cm()->verify_no_references_recorded(); 1315 1316 // Abandon current iterations of concurrent marking and concurrent 1317 // refinement, if any are in progress. We have to do this before 1318 // wait_until_scan_finished() below. 1319 concurrent_mark()->abort(); 1320 1321 // Make sure we'll choose a new allocation region afterwards. 1322 _allocator->release_mutator_alloc_region(); 1323 _allocator->abandon_gc_alloc_regions(); 1324 g1_rem_set()->cleanupHRRS(); 1325 1326 // We should call this after we retire any currently active alloc 1327 // regions so that all the ALLOC / RETIRE events are generated 1328 // before the start GC event. 1329 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1330 1331 // We may have added regions to the current incremental collection 1332 // set between the last GC or pause and now. We need to clear the 1333 // incremental collection set and then start rebuilding it afresh 1334 // after this full GC. 1335 abandon_collection_set(g1_policy()->inc_cset_head()); 1336 g1_policy()->clear_incremental_cset(); 1337 g1_policy()->stop_incremental_cset_building(); 1338 1339 tear_down_region_sets(false /* free_list_only */); 1340 collector_state()->set_gcs_are_young(true); 1341 1342 // See the comments in g1CollectedHeap.hpp and 1343 // G1CollectedHeap::ref_processing_init() about 1344 // how reference processing currently works in G1. 1345 1346 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1347 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1348 1349 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1350 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1351 1352 ref_processor_stw()->enable_discovery(); 1353 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1354 1355 // Do collection work 1356 { 1357 HandleMark hm; // Discard invalid handles created during gc 1358 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1359 } 1360 1361 assert(num_free_regions() == 0, "we should not have added any free regions"); 1362 rebuild_region_sets(false /* free_list_only */); 1363 1364 // Enqueue any discovered reference objects that have 1365 // not been removed from the discovered lists. 1366 ref_processor_stw()->enqueue_discovered_references(); 1367 1368 #if defined(COMPILER2) || INCLUDE_JVMCI 1369 DerivedPointerTable::update_pointers(); 1370 #endif 1371 1372 MemoryService::track_memory_usage(); 1373 1374 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1375 ref_processor_stw()->verify_no_references_recorded(); 1376 1377 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1378 ClassLoaderDataGraph::purge(); 1379 MetaspaceAux::verify_metrics(); 1380 1381 // Note: since we've just done a full GC, concurrent 1382 // marking is no longer active. Therefore we need not 1383 // re-enable reference discovery for the CM ref processor. 1384 // That will be done at the start of the next marking cycle. 1385 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1386 ref_processor_cm()->verify_no_references_recorded(); 1387 1388 reset_gc_time_stamp(); 1389 // Since everything potentially moved, we will clear all remembered 1390 // sets, and clear all cards. Later we will rebuild remembered 1391 // sets. We will also reset the GC time stamps of the regions. 1392 clear_rsets_post_compaction(); 1393 check_gc_time_stamps(); 1394 1395 // Resize the heap if necessary. 1396 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1397 1398 if (_hr_printer.is_active()) { 1399 // We should do this after we potentially resize the heap so 1400 // that all the COMMIT / UNCOMMIT events are generated before 1401 // the end GC event. 1402 1403 print_hrm_post_compaction(); 1404 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1405 } 1406 1407 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1408 if (hot_card_cache->use_cache()) { 1409 hot_card_cache->reset_card_counts(); 1410 hot_card_cache->reset_hot_cache(); 1411 } 1412 1413 // Rebuild remembered sets of all regions. 1414 uint n_workers = 1415 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1416 workers()->active_workers(), 1417 Threads::number_of_non_daemon_threads()); 1418 workers()->set_active_workers(n_workers); 1419 1420 ParRebuildRSTask rebuild_rs_task(this); 1421 workers()->run_task(&rebuild_rs_task); 1422 1423 // Rebuild the strong code root lists for each region 1424 rebuild_strong_code_roots(); 1425 1426 if (true) { // FIXME 1427 MetaspaceGC::compute_new_size(); 1428 } 1429 1430 #ifdef TRACESPINNING 1431 ParallelTaskTerminator::print_termination_counts(); 1432 #endif 1433 1434 // Discard all rset updates 1435 JavaThread::dirty_card_queue_set().abandon_logs(); 1436 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1437 1438 _young_list->reset_sampled_info(); 1439 // At this point there should be no regions in the 1440 // entire heap tagged as young. 1441 assert(check_young_list_empty(true /* check_heap */), 1442 "young list should be empty at this point"); 1443 1444 // Update the number of full collections that have been completed. 1445 increment_old_marking_cycles_completed(false /* concurrent */); 1446 1447 _hrm.verify_optional(); 1448 verify_region_sets_optional(); 1449 1450 verify_after_gc(); 1451 1452 // Clear the previous marking bitmap, if needed for bitmap verification. 1453 // Note we cannot do this when we clear the next marking bitmap in 1454 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1455 // objects marked during a full GC against the previous bitmap. 1456 // But we need to clear it before calling check_bitmaps below since 1457 // the full GC has compacted objects and updated TAMS but not updated 1458 // the prev bitmap. 1459 if (G1VerifyBitmaps) { 1460 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1461 } 1462 check_bitmaps("Full GC End"); 1463 1464 // Start a new incremental collection set for the next pause 1465 assert(g1_policy()->collection_set() == NULL, "must be"); 1466 g1_policy()->start_incremental_cset_building(); 1467 1468 clear_cset_fast_test(); 1469 1470 _allocator->init_mutator_alloc_region(); 1471 1472 g1_policy()->record_full_collection_end(); 1473 1474 if (G1Log::fine()) { 1475 g1_policy()->print_heap_transition(); 1476 } 1477 1478 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1479 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1480 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1481 // before any GC notifications are raised. 1482 g1mm()->update_sizes(); 1483 1484 gc_epilogue(true); 1485 } 1486 1487 if (G1Log::finer()) { 1488 g1_policy()->print_detailed_heap_transition(true /* full */); 1489 } 1490 1491 print_heap_after_gc(); 1492 trace_heap_after_gc(gc_tracer); 1493 1494 post_full_gc_dump(gc_timer); 1495 1496 gc_timer->register_gc_end(); 1497 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1498 } 1499 1500 return true; 1501 } 1502 1503 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1504 // do_collection() will return whether it succeeded in performing 1505 // the GC. Currently, there is no facility on the 1506 // do_full_collection() API to notify the caller than the collection 1507 // did not succeed (e.g., because it was locked out by the GC 1508 // locker). So, right now, we'll ignore the return value. 1509 bool dummy = do_collection(true, /* explicit_gc */ 1510 clear_all_soft_refs, 1511 0 /* word_size */); 1512 } 1513 1514 // This code is mostly copied from TenuredGeneration. 1515 void 1516 G1CollectedHeap:: 1517 resize_if_necessary_after_full_collection(size_t word_size) { 1518 // Include the current allocation, if any, and bytes that will be 1519 // pre-allocated to support collections, as "used". 1520 const size_t used_after_gc = used(); 1521 const size_t capacity_after_gc = capacity(); 1522 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1523 1524 // This is enforced in arguments.cpp. 1525 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1526 "otherwise the code below doesn't make sense"); 1527 1528 // We don't have floating point command-line arguments 1529 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1530 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1531 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1532 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1533 1534 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1535 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1536 1537 // We have to be careful here as these two calculations can overflow 1538 // 32-bit size_t's. 1539 double used_after_gc_d = (double) used_after_gc; 1540 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1541 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1542 1543 // Let's make sure that they are both under the max heap size, which 1544 // by default will make them fit into a size_t. 1545 double desired_capacity_upper_bound = (double) max_heap_size; 1546 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1547 desired_capacity_upper_bound); 1548 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1549 desired_capacity_upper_bound); 1550 1551 // We can now safely turn them into size_t's. 1552 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1553 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1554 1555 // This assert only makes sense here, before we adjust them 1556 // with respect to the min and max heap size. 1557 assert(minimum_desired_capacity <= maximum_desired_capacity, 1558 "minimum_desired_capacity = " SIZE_FORMAT ", " 1559 "maximum_desired_capacity = " SIZE_FORMAT, 1560 minimum_desired_capacity, maximum_desired_capacity); 1561 1562 // Should not be greater than the heap max size. No need to adjust 1563 // it with respect to the heap min size as it's a lower bound (i.e., 1564 // we'll try to make the capacity larger than it, not smaller). 1565 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1566 // Should not be less than the heap min size. No need to adjust it 1567 // with respect to the heap max size as it's an upper bound (i.e., 1568 // we'll try to make the capacity smaller than it, not greater). 1569 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1570 1571 if (capacity_after_gc < minimum_desired_capacity) { 1572 // Don't expand unless it's significant 1573 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1574 ergo_verbose4(ErgoHeapSizing, 1575 "attempt heap expansion", 1576 ergo_format_reason("capacity lower than " 1577 "min desired capacity after Full GC") 1578 ergo_format_byte("capacity") 1579 ergo_format_byte("occupancy") 1580 ergo_format_byte_perc("min desired capacity"), 1581 capacity_after_gc, used_after_gc, 1582 minimum_desired_capacity, (double) MinHeapFreeRatio); 1583 expand(expand_bytes); 1584 1585 // No expansion, now see if we want to shrink 1586 } else if (capacity_after_gc > maximum_desired_capacity) { 1587 // Capacity too large, compute shrinking size 1588 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1589 ergo_verbose4(ErgoHeapSizing, 1590 "attempt heap shrinking", 1591 ergo_format_reason("capacity higher than " 1592 "max desired capacity after Full GC") 1593 ergo_format_byte("capacity") 1594 ergo_format_byte("occupancy") 1595 ergo_format_byte_perc("max desired capacity"), 1596 capacity_after_gc, used_after_gc, 1597 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1598 shrink(shrink_bytes); 1599 } 1600 } 1601 1602 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1603 AllocationContext_t context, 1604 bool do_gc, 1605 bool clear_all_soft_refs, 1606 bool expect_null_mutator_alloc_region, 1607 bool* gc_succeeded) { 1608 *gc_succeeded = true; 1609 // Let's attempt the allocation first. 1610 HeapWord* result = 1611 attempt_allocation_at_safepoint(word_size, 1612 context, 1613 expect_null_mutator_alloc_region); 1614 if (result != NULL) { 1615 assert(*gc_succeeded, "sanity"); 1616 return result; 1617 } 1618 1619 // In a G1 heap, we're supposed to keep allocation from failing by 1620 // incremental pauses. Therefore, at least for now, we'll favor 1621 // expansion over collection. (This might change in the future if we can 1622 // do something smarter than full collection to satisfy a failed alloc.) 1623 result = expand_and_allocate(word_size, context); 1624 if (result != NULL) { 1625 assert(*gc_succeeded, "sanity"); 1626 return result; 1627 } 1628 1629 if (do_gc) { 1630 // Expansion didn't work, we'll try to do a Full GC. 1631 *gc_succeeded = do_collection(false, /* explicit_gc */ 1632 clear_all_soft_refs, 1633 word_size); 1634 } 1635 1636 return NULL; 1637 } 1638 1639 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1640 AllocationContext_t context, 1641 bool* succeeded) { 1642 assert_at_safepoint(true /* should_be_vm_thread */); 1643 1644 // Attempts to allocate followed by Full GC. 1645 HeapWord* result = 1646 satisfy_failed_allocation_helper(word_size, 1647 context, 1648 true, /* do_gc */ 1649 false, /* clear_all_soft_refs */ 1650 false, /* expect_null_mutator_alloc_region */ 1651 succeeded); 1652 1653 if (result != NULL || !*succeeded) { 1654 return result; 1655 } 1656 1657 // Attempts to allocate followed by Full GC that will collect all soft references. 1658 result = satisfy_failed_allocation_helper(word_size, 1659 context, 1660 true, /* do_gc */ 1661 true, /* clear_all_soft_refs */ 1662 true, /* expect_null_mutator_alloc_region */ 1663 succeeded); 1664 1665 if (result != NULL || !*succeeded) { 1666 return result; 1667 } 1668 1669 // Attempts to allocate, no GC 1670 result = satisfy_failed_allocation_helper(word_size, 1671 context, 1672 false, /* do_gc */ 1673 false, /* clear_all_soft_refs */ 1674 true, /* expect_null_mutator_alloc_region */ 1675 succeeded); 1676 1677 if (result != NULL) { 1678 assert(*succeeded, "sanity"); 1679 return result; 1680 } 1681 1682 assert(!collector_policy()->should_clear_all_soft_refs(), 1683 "Flag should have been handled and cleared prior to this point"); 1684 1685 // What else? We might try synchronous finalization later. If the total 1686 // space available is large enough for the allocation, then a more 1687 // complete compaction phase than we've tried so far might be 1688 // appropriate. 1689 assert(*succeeded, "sanity"); 1690 return NULL; 1691 } 1692 1693 // Attempting to expand the heap sufficiently 1694 // to support an allocation of the given "word_size". If 1695 // successful, perform the allocation and return the address of the 1696 // allocated block, or else "NULL". 1697 1698 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1699 assert_at_safepoint(true /* should_be_vm_thread */); 1700 1701 verify_region_sets_optional(); 1702 1703 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1704 ergo_verbose1(ErgoHeapSizing, 1705 "attempt heap expansion", 1706 ergo_format_reason("allocation request failed") 1707 ergo_format_byte("allocation request"), 1708 word_size * HeapWordSize); 1709 if (expand(expand_bytes)) { 1710 _hrm.verify_optional(); 1711 verify_region_sets_optional(); 1712 return attempt_allocation_at_safepoint(word_size, 1713 context, 1714 false /* expect_null_mutator_alloc_region */); 1715 } 1716 return NULL; 1717 } 1718 1719 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) { 1720 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1721 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1722 HeapRegion::GrainBytes); 1723 ergo_verbose2(ErgoHeapSizing, 1724 "expand the heap", 1725 ergo_format_byte("requested expansion amount") 1726 ergo_format_byte("attempted expansion amount"), 1727 expand_bytes, aligned_expand_bytes); 1728 1729 if (is_maximal_no_gc()) { 1730 ergo_verbose0(ErgoHeapSizing, 1731 "did not expand the heap", 1732 ergo_format_reason("heap already fully expanded")); 1733 return false; 1734 } 1735 1736 double expand_heap_start_time_sec = os::elapsedTime(); 1737 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1738 assert(regions_to_expand > 0, "Must expand by at least one region"); 1739 1740 uint expanded_by = _hrm.expand_by(regions_to_expand); 1741 if (expand_time_ms != NULL) { 1742 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1743 } 1744 1745 if (expanded_by > 0) { 1746 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1747 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1748 g1_policy()->record_new_heap_size(num_regions()); 1749 } else { 1750 ergo_verbose0(ErgoHeapSizing, 1751 "did not expand the heap", 1752 ergo_format_reason("heap expansion operation failed")); 1753 // The expansion of the virtual storage space was unsuccessful. 1754 // Let's see if it was because we ran out of swap. 1755 if (G1ExitOnExpansionFailure && 1756 _hrm.available() >= regions_to_expand) { 1757 // We had head room... 1758 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1759 } 1760 } 1761 return regions_to_expand > 0; 1762 } 1763 1764 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1765 size_t aligned_shrink_bytes = 1766 ReservedSpace::page_align_size_down(shrink_bytes); 1767 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1768 HeapRegion::GrainBytes); 1769 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1770 1771 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1772 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1773 1774 ergo_verbose3(ErgoHeapSizing, 1775 "shrink the heap", 1776 ergo_format_byte("requested shrinking amount") 1777 ergo_format_byte("aligned shrinking amount") 1778 ergo_format_byte("attempted shrinking amount"), 1779 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1780 if (num_regions_removed > 0) { 1781 g1_policy()->record_new_heap_size(num_regions()); 1782 } else { 1783 ergo_verbose0(ErgoHeapSizing, 1784 "did not shrink the heap", 1785 ergo_format_reason("heap shrinking operation failed")); 1786 } 1787 } 1788 1789 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1790 verify_region_sets_optional(); 1791 1792 // We should only reach here at the end of a Full GC which means we 1793 // should not not be holding to any GC alloc regions. The method 1794 // below will make sure of that and do any remaining clean up. 1795 _allocator->abandon_gc_alloc_regions(); 1796 1797 // Instead of tearing down / rebuilding the free lists here, we 1798 // could instead use the remove_all_pending() method on free_list to 1799 // remove only the ones that we need to remove. 1800 tear_down_region_sets(true /* free_list_only */); 1801 shrink_helper(shrink_bytes); 1802 rebuild_region_sets(true /* free_list_only */); 1803 1804 _hrm.verify_optional(); 1805 verify_region_sets_optional(); 1806 } 1807 1808 // Public methods. 1809 1810 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1811 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1812 #endif // _MSC_VER 1813 1814 1815 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1816 CollectedHeap(), 1817 _g1_policy(policy_), 1818 _dirty_card_queue_set(false), 1819 _into_cset_dirty_card_queue_set(false), 1820 _is_alive_closure_cm(this), 1821 _is_alive_closure_stw(this), 1822 _ref_processor_cm(NULL), 1823 _ref_processor_stw(NULL), 1824 _bot_shared(NULL), 1825 _cg1r(NULL), 1826 _g1mm(NULL), 1827 _refine_cte_cl(NULL), 1828 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1829 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1830 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1831 _humongous_reclaim_candidates(), 1832 _has_humongous_reclaim_candidates(false), 1833 _archive_allocator(NULL), 1834 _free_regions_coming(false), 1835 _young_list(new YoungList(this)), 1836 _gc_time_stamp(0), 1837 _summary_bytes_used(0), 1838 _survivor_evac_stats(YoungPLABSize, PLABWeight), 1839 _old_evac_stats(OldPLABSize, PLABWeight), 1840 _expand_heap_after_alloc_failure(true), 1841 _old_marking_cycles_started(0), 1842 _old_marking_cycles_completed(0), 1843 _heap_summary_sent(false), 1844 _in_cset_fast_test(), 1845 _dirty_cards_region_list(NULL), 1846 _worker_cset_start_region(NULL), 1847 _worker_cset_start_region_time_stamp(NULL), 1848 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1849 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1850 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1851 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1852 1853 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1854 /* are_GC_task_threads */true, 1855 /* are_ConcurrentGC_threads */false); 1856 _workers->initialize_workers(); 1857 1858 _allocator = G1Allocator::create_allocator(this); 1859 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1860 1861 // Override the default _filler_array_max_size so that no humongous filler 1862 // objects are created. 1863 _filler_array_max_size = _humongous_object_threshold_in_words; 1864 1865 uint n_queues = ParallelGCThreads; 1866 _task_queues = new RefToScanQueueSet(n_queues); 1867 1868 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1869 assert(n_rem_sets > 0, "Invariant."); 1870 1871 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1872 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC); 1873 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1874 1875 for (uint i = 0; i < n_queues; i++) { 1876 RefToScanQueue* q = new RefToScanQueue(); 1877 q->initialize(); 1878 _task_queues->register_queue(i, q); 1879 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1880 } 1881 clear_cset_start_regions(); 1882 1883 // Initialize the G1EvacuationFailureALot counters and flags. 1884 NOT_PRODUCT(reset_evacuation_should_fail();) 1885 1886 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1887 } 1888 1889 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1890 size_t size, 1891 size_t translation_factor) { 1892 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1893 // Allocate a new reserved space, preferring to use large pages. 1894 ReservedSpace rs(size, preferred_page_size); 1895 G1RegionToSpaceMapper* result = 1896 G1RegionToSpaceMapper::create_mapper(rs, 1897 size, 1898 rs.alignment(), 1899 HeapRegion::GrainBytes, 1900 translation_factor, 1901 mtGC); 1902 if (TracePageSizes) { 1903 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT, 1904 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size); 1905 } 1906 return result; 1907 } 1908 1909 jint G1CollectedHeap::initialize() { 1910 CollectedHeap::pre_initialize(); 1911 os::enable_vtime(); 1912 1913 G1Log::init(); 1914 1915 // Necessary to satisfy locking discipline assertions. 1916 1917 MutexLocker x(Heap_lock); 1918 1919 // We have to initialize the printer before committing the heap, as 1920 // it will be used then. 1921 _hr_printer.set_active(G1PrintHeapRegions); 1922 1923 // While there are no constraints in the GC code that HeapWordSize 1924 // be any particular value, there are multiple other areas in the 1925 // system which believe this to be true (e.g. oop->object_size in some 1926 // cases incorrectly returns the size in wordSize units rather than 1927 // HeapWordSize). 1928 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1929 1930 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1931 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1932 size_t heap_alignment = collector_policy()->heap_alignment(); 1933 1934 // Ensure that the sizes are properly aligned. 1935 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1936 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1937 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1938 1939 _refine_cte_cl = new RefineCardTableEntryClosure(); 1940 1941 jint ecode = JNI_OK; 1942 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode); 1943 if (_cg1r == NULL) { 1944 return ecode; 1945 } 1946 1947 // Reserve the maximum. 1948 1949 // When compressed oops are enabled, the preferred heap base 1950 // is calculated by subtracting the requested size from the 1951 // 32Gb boundary and using the result as the base address for 1952 // heap reservation. If the requested size is not aligned to 1953 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1954 // into the ReservedHeapSpace constructor) then the actual 1955 // base of the reserved heap may end up differing from the 1956 // address that was requested (i.e. the preferred heap base). 1957 // If this happens then we could end up using a non-optimal 1958 // compressed oops mode. 1959 1960 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1961 heap_alignment); 1962 1963 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1964 1965 // Create the barrier set for the entire reserved region. 1966 G1SATBCardTableLoggingModRefBS* bs 1967 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 1968 bs->initialize(); 1969 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 1970 set_barrier_set(bs); 1971 1972 // Also create a G1 rem set. 1973 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 1974 1975 // Carve out the G1 part of the heap. 1976 1977 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1978 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 1979 G1RegionToSpaceMapper* heap_storage = 1980 G1RegionToSpaceMapper::create_mapper(g1_rs, 1981 g1_rs.size(), 1982 page_size, 1983 HeapRegion::GrainBytes, 1984 1, 1985 mtJavaHeap); 1986 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(), 1987 max_byte_size, page_size, 1988 heap_rs.base(), 1989 heap_rs.size()); 1990 heap_storage->set_mapping_changed_listener(&_listener); 1991 1992 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1993 G1RegionToSpaceMapper* bot_storage = 1994 create_aux_memory_mapper("Block offset table", 1995 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize), 1996 G1BlockOffsetSharedArray::heap_map_factor()); 1997 1998 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 1999 G1RegionToSpaceMapper* cardtable_storage = 2000 create_aux_memory_mapper("Card table", 2001 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize), 2002 G1SATBCardTableLoggingModRefBS::heap_map_factor()); 2003 2004 G1RegionToSpaceMapper* card_counts_storage = 2005 create_aux_memory_mapper("Card counts table", 2006 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 2007 G1CardCounts::heap_map_factor()); 2008 2009 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); 2010 G1RegionToSpaceMapper* prev_bitmap_storage = 2011 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor()); 2012 G1RegionToSpaceMapper* next_bitmap_storage = 2013 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor()); 2014 2015 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 2016 g1_barrier_set()->initialize(cardtable_storage); 2017 // Do later initialization work for concurrent refinement. 2018 _cg1r->init(card_counts_storage); 2019 2020 // 6843694 - ensure that the maximum region index can fit 2021 // in the remembered set structures. 2022 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2023 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2024 2025 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2026 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2027 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2028 "too many cards per region"); 2029 2030 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 2031 2032 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage); 2033 2034 { 2035 HeapWord* start = _hrm.reserved().start(); 2036 HeapWord* end = _hrm.reserved().end(); 2037 size_t granularity = HeapRegion::GrainBytes; 2038 2039 _in_cset_fast_test.initialize(start, end, granularity); 2040 _humongous_reclaim_candidates.initialize(start, end, granularity); 2041 } 2042 2043 // Create the ConcurrentMark data structure and thread. 2044 // (Must do this late, so that "max_regions" is defined.) 2045 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 2046 if (_cm == NULL || !_cm->completed_initialization()) { 2047 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 2048 return JNI_ENOMEM; 2049 } 2050 _cmThread = _cm->cmThread(); 2051 2052 // Initialize the from_card cache structure of HeapRegionRemSet. 2053 HeapRegionRemSet::init_heap(max_regions()); 2054 2055 // Now expand into the initial heap size. 2056 if (!expand(init_byte_size)) { 2057 vm_shutdown_during_initialization("Failed to allocate initial heap."); 2058 return JNI_ENOMEM; 2059 } 2060 2061 // Perform any initialization actions delegated to the policy. 2062 g1_policy()->init(); 2063 2064 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2065 SATB_Q_FL_lock, 2066 G1SATBProcessCompletedThreshold, 2067 Shared_SATB_Q_lock); 2068 2069 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 2070 DirtyCardQ_CBL_mon, 2071 DirtyCardQ_FL_lock, 2072 concurrent_g1_refine()->yellow_zone(), 2073 concurrent_g1_refine()->red_zone(), 2074 Shared_DirtyCardQ_lock); 2075 2076 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 2077 DirtyCardQ_CBL_mon, 2078 DirtyCardQ_FL_lock, 2079 -1, // never trigger processing 2080 -1, // no limit on length 2081 Shared_DirtyCardQ_lock, 2082 &JavaThread::dirty_card_queue_set()); 2083 2084 // Initialize the card queue set used to hold cards containing 2085 // references into the collection set. 2086 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 2087 DirtyCardQ_CBL_mon, 2088 DirtyCardQ_FL_lock, 2089 -1, // never trigger processing 2090 -1, // no limit on length 2091 Shared_DirtyCardQ_lock, 2092 &JavaThread::dirty_card_queue_set()); 2093 2094 // Here we allocate the dummy HeapRegion that is required by the 2095 // G1AllocRegion class. 2096 HeapRegion* dummy_region = _hrm.get_dummy_region(); 2097 2098 // We'll re-use the same region whether the alloc region will 2099 // require BOT updates or not and, if it doesn't, then a non-young 2100 // region will complain that it cannot support allocations without 2101 // BOT updates. So we'll tag the dummy region as eden to avoid that. 2102 dummy_region->set_eden(); 2103 // Make sure it's full. 2104 dummy_region->set_top(dummy_region->end()); 2105 G1AllocRegion::setup(this, dummy_region); 2106 2107 _allocator->init_mutator_alloc_region(); 2108 2109 // Do create of the monitoring and management support so that 2110 // values in the heap have been properly initialized. 2111 _g1mm = new G1MonitoringSupport(this); 2112 2113 G1StringDedup::initialize(); 2114 2115 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC); 2116 for (uint i = 0; i < ParallelGCThreads; i++) { 2117 new (&_preserved_objs[i]) OopAndMarkOopStack(); 2118 } 2119 2120 return JNI_OK; 2121 } 2122 2123 void G1CollectedHeap::stop() { 2124 // Stop all concurrent threads. We do this to make sure these threads 2125 // do not continue to execute and access resources (e.g. gclog_or_tty) 2126 // that are destroyed during shutdown. 2127 _cg1r->stop(); 2128 _cmThread->stop(); 2129 if (G1StringDedup::is_enabled()) { 2130 G1StringDedup::stop(); 2131 } 2132 } 2133 2134 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2135 return HeapRegion::max_region_size(); 2136 } 2137 2138 void G1CollectedHeap::post_initialize() { 2139 CollectedHeap::post_initialize(); 2140 ref_processing_init(); 2141 } 2142 2143 void G1CollectedHeap::ref_processing_init() { 2144 // Reference processing in G1 currently works as follows: 2145 // 2146 // * There are two reference processor instances. One is 2147 // used to record and process discovered references 2148 // during concurrent marking; the other is used to 2149 // record and process references during STW pauses 2150 // (both full and incremental). 2151 // * Both ref processors need to 'span' the entire heap as 2152 // the regions in the collection set may be dotted around. 2153 // 2154 // * For the concurrent marking ref processor: 2155 // * Reference discovery is enabled at initial marking. 2156 // * Reference discovery is disabled and the discovered 2157 // references processed etc during remarking. 2158 // * Reference discovery is MT (see below). 2159 // * Reference discovery requires a barrier (see below). 2160 // * Reference processing may or may not be MT 2161 // (depending on the value of ParallelRefProcEnabled 2162 // and ParallelGCThreads). 2163 // * A full GC disables reference discovery by the CM 2164 // ref processor and abandons any entries on it's 2165 // discovered lists. 2166 // 2167 // * For the STW processor: 2168 // * Non MT discovery is enabled at the start of a full GC. 2169 // * Processing and enqueueing during a full GC is non-MT. 2170 // * During a full GC, references are processed after marking. 2171 // 2172 // * Discovery (may or may not be MT) is enabled at the start 2173 // of an incremental evacuation pause. 2174 // * References are processed near the end of a STW evacuation pause. 2175 // * For both types of GC: 2176 // * Discovery is atomic - i.e. not concurrent. 2177 // * Reference discovery will not need a barrier. 2178 2179 MemRegion mr = reserved_region(); 2180 2181 // Concurrent Mark ref processor 2182 _ref_processor_cm = 2183 new ReferenceProcessor(mr, // span 2184 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2185 // mt processing 2186 ParallelGCThreads, 2187 // degree of mt processing 2188 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2189 // mt discovery 2190 MAX2(ParallelGCThreads, ConcGCThreads), 2191 // degree of mt discovery 2192 false, 2193 // Reference discovery is not atomic 2194 &_is_alive_closure_cm); 2195 // is alive closure 2196 // (for efficiency/performance) 2197 2198 // STW ref processor 2199 _ref_processor_stw = 2200 new ReferenceProcessor(mr, // span 2201 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2202 // mt processing 2203 ParallelGCThreads, 2204 // degree of mt processing 2205 (ParallelGCThreads > 1), 2206 // mt discovery 2207 ParallelGCThreads, 2208 // degree of mt discovery 2209 true, 2210 // Reference discovery is atomic 2211 &_is_alive_closure_stw); 2212 // is alive closure 2213 // (for efficiency/performance) 2214 } 2215 2216 CollectorPolicy* G1CollectedHeap::collector_policy() const { 2217 return g1_policy(); 2218 } 2219 2220 size_t G1CollectedHeap::capacity() const { 2221 return _hrm.length() * HeapRegion::GrainBytes; 2222 } 2223 2224 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2225 assert(!hr->is_continues_humongous(), "pre-condition"); 2226 hr->reset_gc_time_stamp(); 2227 if (hr->is_starts_humongous()) { 2228 uint first_index = hr->hrm_index() + 1; 2229 uint last_index = hr->last_hc_index(); 2230 for (uint i = first_index; i < last_index; i += 1) { 2231 HeapRegion* chr = region_at(i); 2232 assert(chr->is_continues_humongous(), "sanity"); 2233 chr->reset_gc_time_stamp(); 2234 } 2235 } 2236 } 2237 2238 #ifndef PRODUCT 2239 2240 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2241 private: 2242 unsigned _gc_time_stamp; 2243 bool _failures; 2244 2245 public: 2246 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2247 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2248 2249 virtual bool doHeapRegion(HeapRegion* hr) { 2250 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2251 if (_gc_time_stamp != region_gc_time_stamp) { 2252 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, " 2253 "expected %d", HR_FORMAT_PARAMS(hr), 2254 region_gc_time_stamp, _gc_time_stamp); 2255 _failures = true; 2256 } 2257 return false; 2258 } 2259 2260 bool failures() { return _failures; } 2261 }; 2262 2263 void G1CollectedHeap::check_gc_time_stamps() { 2264 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2265 heap_region_iterate(&cl); 2266 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2267 } 2268 #endif // PRODUCT 2269 2270 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) { 2271 _cg1r->hot_card_cache()->drain(cl, worker_i); 2272 } 2273 2274 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) { 2275 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2276 size_t n_completed_buffers = 0; 2277 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2278 n_completed_buffers++; 2279 } 2280 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 2281 dcqs.clear_n_completed_buffers(); 2282 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2283 } 2284 2285 // Computes the sum of the storage used by the various regions. 2286 size_t G1CollectedHeap::used() const { 2287 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 2288 if (_archive_allocator != NULL) { 2289 result += _archive_allocator->used(); 2290 } 2291 return result; 2292 } 2293 2294 size_t G1CollectedHeap::used_unlocked() const { 2295 return _summary_bytes_used; 2296 } 2297 2298 class SumUsedClosure: public HeapRegionClosure { 2299 size_t _used; 2300 public: 2301 SumUsedClosure() : _used(0) {} 2302 bool doHeapRegion(HeapRegion* r) { 2303 if (!r->is_continues_humongous()) { 2304 _used += r->used(); 2305 } 2306 return false; 2307 } 2308 size_t result() { return _used; } 2309 }; 2310 2311 size_t G1CollectedHeap::recalculate_used() const { 2312 double recalculate_used_start = os::elapsedTime(); 2313 2314 SumUsedClosure blk; 2315 heap_region_iterate(&blk); 2316 2317 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2318 return blk.result(); 2319 } 2320 2321 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2322 switch (cause) { 2323 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2324 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2325 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 2326 case GCCause::_g1_humongous_allocation: return true; 2327 case GCCause::_update_allocation_context_stats_inc: return true; 2328 case GCCause::_wb_conc_mark: return true; 2329 default: return false; 2330 } 2331 } 2332 2333 #ifndef PRODUCT 2334 void G1CollectedHeap::allocate_dummy_regions() { 2335 // Let's fill up most of the region 2336 size_t word_size = HeapRegion::GrainWords - 1024; 2337 // And as a result the region we'll allocate will be humongous. 2338 guarantee(is_humongous(word_size), "sanity"); 2339 2340 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2341 // Let's use the existing mechanism for the allocation 2342 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2343 AllocationContext::system()); 2344 if (dummy_obj != NULL) { 2345 MemRegion mr(dummy_obj, word_size); 2346 CollectedHeap::fill_with_object(mr); 2347 } else { 2348 // If we can't allocate once, we probably cannot allocate 2349 // again. Let's get out of the loop. 2350 break; 2351 } 2352 } 2353 } 2354 #endif // !PRODUCT 2355 2356 void G1CollectedHeap::increment_old_marking_cycles_started() { 2357 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2358 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2359 "Wrong marking cycle count (started: %d, completed: %d)", 2360 _old_marking_cycles_started, _old_marking_cycles_completed); 2361 2362 _old_marking_cycles_started++; 2363 } 2364 2365 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2366 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2367 2368 // We assume that if concurrent == true, then the caller is a 2369 // concurrent thread that was joined the Suspendible Thread 2370 // Set. If there's ever a cheap way to check this, we should add an 2371 // assert here. 2372 2373 // Given that this method is called at the end of a Full GC or of a 2374 // concurrent cycle, and those can be nested (i.e., a Full GC can 2375 // interrupt a concurrent cycle), the number of full collections 2376 // completed should be either one (in the case where there was no 2377 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2378 // behind the number of full collections started. 2379 2380 // This is the case for the inner caller, i.e. a Full GC. 2381 assert(concurrent || 2382 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2383 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2384 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2385 "is inconsistent with _old_marking_cycles_completed = %u", 2386 _old_marking_cycles_started, _old_marking_cycles_completed); 2387 2388 // This is the case for the outer caller, i.e. the concurrent cycle. 2389 assert(!concurrent || 2390 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2391 "for outer caller (concurrent cycle): " 2392 "_old_marking_cycles_started = %u " 2393 "is inconsistent with _old_marking_cycles_completed = %u", 2394 _old_marking_cycles_started, _old_marking_cycles_completed); 2395 2396 _old_marking_cycles_completed += 1; 2397 2398 // We need to clear the "in_progress" flag in the CM thread before 2399 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2400 // is set) so that if a waiter requests another System.gc() it doesn't 2401 // incorrectly see that a marking cycle is still in progress. 2402 if (concurrent) { 2403 _cmThread->set_idle(); 2404 } 2405 2406 // This notify_all() will ensure that a thread that called 2407 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2408 // and it's waiting for a full GC to finish will be woken up. It is 2409 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2410 FullGCCount_lock->notify_all(); 2411 } 2412 2413 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2414 GCIdMarkAndRestore conc_gc_id_mark; 2415 collector_state()->set_concurrent_cycle_started(true); 2416 _gc_timer_cm->register_gc_start(start_time); 2417 2418 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2419 trace_heap_before_gc(_gc_tracer_cm); 2420 _cmThread->set_gc_id(GCId::current()); 2421 } 2422 2423 void G1CollectedHeap::register_concurrent_cycle_end() { 2424 if (collector_state()->concurrent_cycle_started()) { 2425 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id()); 2426 if (_cm->has_aborted()) { 2427 _gc_tracer_cm->report_concurrent_mode_failure(); 2428 } 2429 2430 _gc_timer_cm->register_gc_end(); 2431 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2432 2433 // Clear state variables to prepare for the next concurrent cycle. 2434 collector_state()->set_concurrent_cycle_started(false); 2435 _heap_summary_sent = false; 2436 } 2437 } 2438 2439 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2440 if (collector_state()->concurrent_cycle_started()) { 2441 // This function can be called when: 2442 // the cleanup pause is run 2443 // the concurrent cycle is aborted before the cleanup pause. 2444 // the concurrent cycle is aborted after the cleanup pause, 2445 // but before the concurrent cycle end has been registered. 2446 // Make sure that we only send the heap information once. 2447 if (!_heap_summary_sent) { 2448 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id()); 2449 trace_heap_after_gc(_gc_tracer_cm); 2450 _heap_summary_sent = true; 2451 } 2452 } 2453 } 2454 2455 void G1CollectedHeap::collect(GCCause::Cause cause) { 2456 assert_heap_not_locked(); 2457 2458 uint gc_count_before; 2459 uint old_marking_count_before; 2460 uint full_gc_count_before; 2461 bool retry_gc; 2462 2463 do { 2464 retry_gc = false; 2465 2466 { 2467 MutexLocker ml(Heap_lock); 2468 2469 // Read the GC count while holding the Heap_lock 2470 gc_count_before = total_collections(); 2471 full_gc_count_before = total_full_collections(); 2472 old_marking_count_before = _old_marking_cycles_started; 2473 } 2474 2475 if (should_do_concurrent_full_gc(cause)) { 2476 // Schedule an initial-mark evacuation pause that will start a 2477 // concurrent cycle. We're setting word_size to 0 which means that 2478 // we are not requesting a post-GC allocation. 2479 VM_G1IncCollectionPause op(gc_count_before, 2480 0, /* word_size */ 2481 true, /* should_initiate_conc_mark */ 2482 g1_policy()->max_pause_time_ms(), 2483 cause); 2484 op.set_allocation_context(AllocationContext::current()); 2485 2486 VMThread::execute(&op); 2487 if (!op.pause_succeeded()) { 2488 if (old_marking_count_before == _old_marking_cycles_started) { 2489 retry_gc = op.should_retry_gc(); 2490 } else { 2491 // A Full GC happened while we were trying to schedule the 2492 // initial-mark GC. No point in starting a new cycle given 2493 // that the whole heap was collected anyway. 2494 } 2495 2496 if (retry_gc) { 2497 if (GC_locker::is_active_and_needs_gc()) { 2498 GC_locker::stall_until_clear(); 2499 } 2500 } 2501 } 2502 } else { 2503 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2504 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2505 2506 // Schedule a standard evacuation pause. We're setting word_size 2507 // to 0 which means that we are not requesting a post-GC allocation. 2508 VM_G1IncCollectionPause op(gc_count_before, 2509 0, /* word_size */ 2510 false, /* should_initiate_conc_mark */ 2511 g1_policy()->max_pause_time_ms(), 2512 cause); 2513 VMThread::execute(&op); 2514 } else { 2515 // Schedule a Full GC. 2516 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2517 VMThread::execute(&op); 2518 } 2519 } 2520 } while (retry_gc); 2521 } 2522 2523 bool G1CollectedHeap::is_in(const void* p) const { 2524 if (_hrm.reserved().contains(p)) { 2525 // Given that we know that p is in the reserved space, 2526 // heap_region_containing_raw() should successfully 2527 // return the containing region. 2528 HeapRegion* hr = heap_region_containing_raw(p); 2529 return hr->is_in(p); 2530 } else { 2531 return false; 2532 } 2533 } 2534 2535 #ifdef ASSERT 2536 bool G1CollectedHeap::is_in_exact(const void* p) const { 2537 bool contains = reserved_region().contains(p); 2538 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2539 if (contains && available) { 2540 return true; 2541 } else { 2542 return false; 2543 } 2544 } 2545 #endif 2546 2547 bool G1CollectedHeap::obj_in_cs(oop obj) { 2548 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj); 2549 return r != NULL && r->in_collection_set(); 2550 } 2551 2552 // Iteration functions. 2553 2554 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2555 2556 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2557 ExtendedOopClosure* _cl; 2558 public: 2559 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2560 bool doHeapRegion(HeapRegion* r) { 2561 if (!r->is_continues_humongous()) { 2562 r->oop_iterate(_cl); 2563 } 2564 return false; 2565 } 2566 }; 2567 2568 // Iterates an ObjectClosure over all objects within a HeapRegion. 2569 2570 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2571 ObjectClosure* _cl; 2572 public: 2573 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2574 bool doHeapRegion(HeapRegion* r) { 2575 if (!r->is_continues_humongous()) { 2576 r->object_iterate(_cl); 2577 } 2578 return false; 2579 } 2580 }; 2581 2582 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2583 IterateObjectClosureRegionClosure blk(cl); 2584 heap_region_iterate(&blk); 2585 } 2586 2587 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2588 _hrm.iterate(cl); 2589 } 2590 2591 void 2592 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, 2593 uint worker_id, 2594 HeapRegionClaimer *hrclaimer, 2595 bool concurrent) const { 2596 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); 2597 } 2598 2599 // Clear the cached CSet starting regions and (more importantly) 2600 // the time stamps. Called when we reset the GC time stamp. 2601 void G1CollectedHeap::clear_cset_start_regions() { 2602 assert(_worker_cset_start_region != NULL, "sanity"); 2603 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2604 2605 for (uint i = 0; i < ParallelGCThreads; i++) { 2606 _worker_cset_start_region[i] = NULL; 2607 _worker_cset_start_region_time_stamp[i] = 0; 2608 } 2609 } 2610 2611 // Given the id of a worker, obtain or calculate a suitable 2612 // starting region for iterating over the current collection set. 2613 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2614 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2615 2616 HeapRegion* result = NULL; 2617 unsigned gc_time_stamp = get_gc_time_stamp(); 2618 2619 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2620 // Cached starting region for current worker was set 2621 // during the current pause - so it's valid. 2622 // Note: the cached starting heap region may be NULL 2623 // (when the collection set is empty). 2624 result = _worker_cset_start_region[worker_i]; 2625 assert(result == NULL || result->in_collection_set(), "sanity"); 2626 return result; 2627 } 2628 2629 // The cached entry was not valid so let's calculate 2630 // a suitable starting heap region for this worker. 2631 2632 // We want the parallel threads to start their collection 2633 // set iteration at different collection set regions to 2634 // avoid contention. 2635 // If we have: 2636 // n collection set regions 2637 // p threads 2638 // Then thread t will start at region floor ((t * n) / p) 2639 2640 result = g1_policy()->collection_set(); 2641 uint cs_size = g1_policy()->cset_region_length(); 2642 uint active_workers = workers()->active_workers(); 2643 2644 uint end_ind = (cs_size * worker_i) / active_workers; 2645 uint start_ind = 0; 2646 2647 if (worker_i > 0 && 2648 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2649 // Previous workers starting region is valid 2650 // so let's iterate from there 2651 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2652 result = _worker_cset_start_region[worker_i - 1]; 2653 } 2654 2655 for (uint i = start_ind; i < end_ind; i++) { 2656 result = result->next_in_collection_set(); 2657 } 2658 2659 // Note: the calculated starting heap region may be NULL 2660 // (when the collection set is empty). 2661 assert(result == NULL || result->in_collection_set(), "sanity"); 2662 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2663 "should be updated only once per pause"); 2664 _worker_cset_start_region[worker_i] = result; 2665 OrderAccess::storestore(); 2666 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2667 return result; 2668 } 2669 2670 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2671 HeapRegion* r = g1_policy()->collection_set(); 2672 while (r != NULL) { 2673 HeapRegion* next = r->next_in_collection_set(); 2674 if (cl->doHeapRegion(r)) { 2675 cl->incomplete(); 2676 return; 2677 } 2678 r = next; 2679 } 2680 } 2681 2682 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2683 HeapRegionClosure *cl) { 2684 if (r == NULL) { 2685 // The CSet is empty so there's nothing to do. 2686 return; 2687 } 2688 2689 assert(r->in_collection_set(), 2690 "Start region must be a member of the collection set."); 2691 HeapRegion* cur = r; 2692 while (cur != NULL) { 2693 HeapRegion* next = cur->next_in_collection_set(); 2694 if (cl->doHeapRegion(cur) && false) { 2695 cl->incomplete(); 2696 return; 2697 } 2698 cur = next; 2699 } 2700 cur = g1_policy()->collection_set(); 2701 while (cur != r) { 2702 HeapRegion* next = cur->next_in_collection_set(); 2703 if (cl->doHeapRegion(cur) && false) { 2704 cl->incomplete(); 2705 return; 2706 } 2707 cur = next; 2708 } 2709 } 2710 2711 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2712 HeapRegion* result = _hrm.next_region_in_heap(from); 2713 while (result != NULL && result->is_pinned()) { 2714 result = _hrm.next_region_in_heap(result); 2715 } 2716 return result; 2717 } 2718 2719 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2720 HeapRegion* hr = heap_region_containing(addr); 2721 return hr->block_start(addr); 2722 } 2723 2724 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2725 HeapRegion* hr = heap_region_containing(addr); 2726 return hr->block_size(addr); 2727 } 2728 2729 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2730 HeapRegion* hr = heap_region_containing(addr); 2731 return hr->block_is_obj(addr); 2732 } 2733 2734 bool G1CollectedHeap::supports_tlab_allocation() const { 2735 return true; 2736 } 2737 2738 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2739 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2740 } 2741 2742 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2743 return young_list()->eden_used_bytes(); 2744 } 2745 2746 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2747 // must be equal to the humongous object limit. 2748 size_t G1CollectedHeap::max_tlab_size() const { 2749 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment); 2750 } 2751 2752 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2753 AllocationContext_t context = AllocationContext::current(); 2754 return _allocator->unsafe_max_tlab_alloc(context); 2755 } 2756 2757 size_t G1CollectedHeap::max_capacity() const { 2758 return _hrm.reserved().byte_size(); 2759 } 2760 2761 jlong G1CollectedHeap::millis_since_last_gc() { 2762 // assert(false, "NYI"); 2763 return 0; 2764 } 2765 2766 void G1CollectedHeap::prepare_for_verify() { 2767 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2768 ensure_parsability(false); 2769 } 2770 g1_rem_set()->prepare_for_verify(); 2771 } 2772 2773 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 2774 VerifyOption vo) { 2775 switch (vo) { 2776 case VerifyOption_G1UsePrevMarking: 2777 return hr->obj_allocated_since_prev_marking(obj); 2778 case VerifyOption_G1UseNextMarking: 2779 return hr->obj_allocated_since_next_marking(obj); 2780 case VerifyOption_G1UseMarkWord: 2781 return false; 2782 default: 2783 ShouldNotReachHere(); 2784 } 2785 return false; // keep some compilers happy 2786 } 2787 2788 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 2789 switch (vo) { 2790 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 2791 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 2792 case VerifyOption_G1UseMarkWord: return NULL; 2793 default: ShouldNotReachHere(); 2794 } 2795 return NULL; // keep some compilers happy 2796 } 2797 2798 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 2799 switch (vo) { 2800 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 2801 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 2802 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 2803 default: ShouldNotReachHere(); 2804 } 2805 return false; // keep some compilers happy 2806 } 2807 2808 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 2809 switch (vo) { 2810 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 2811 case VerifyOption_G1UseNextMarking: return "NTAMS"; 2812 case VerifyOption_G1UseMarkWord: return "NONE"; 2813 default: ShouldNotReachHere(); 2814 } 2815 return NULL; // keep some compilers happy 2816 } 2817 2818 class VerifyRootsClosure: public OopClosure { 2819 private: 2820 G1CollectedHeap* _g1h; 2821 VerifyOption _vo; 2822 bool _failures; 2823 public: 2824 // _vo == UsePrevMarking -> use "prev" marking information, 2825 // _vo == UseNextMarking -> use "next" marking information, 2826 // _vo == UseMarkWord -> use mark word from object header. 2827 VerifyRootsClosure(VerifyOption vo) : 2828 _g1h(G1CollectedHeap::heap()), 2829 _vo(vo), 2830 _failures(false) { } 2831 2832 bool failures() { return _failures; } 2833 2834 template <class T> void do_oop_nv(T* p) { 2835 T heap_oop = oopDesc::load_heap_oop(p); 2836 if (!oopDesc::is_null(heap_oop)) { 2837 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2838 if (_g1h->is_obj_dead_cond(obj, _vo)) { 2839 gclog_or_tty->print_cr("Root location " PTR_FORMAT " " 2840 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj)); 2841 if (_vo == VerifyOption_G1UseMarkWord) { 2842 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark()); 2843 } 2844 obj->print_on(gclog_or_tty); 2845 _failures = true; 2846 } 2847 } 2848 } 2849 2850 void do_oop(oop* p) { do_oop_nv(p); } 2851 void do_oop(narrowOop* p) { do_oop_nv(p); } 2852 }; 2853 2854 class G1VerifyCodeRootOopClosure: public OopClosure { 2855 G1CollectedHeap* _g1h; 2856 OopClosure* _root_cl; 2857 nmethod* _nm; 2858 VerifyOption _vo; 2859 bool _failures; 2860 2861 template <class T> void do_oop_work(T* p) { 2862 // First verify that this root is live 2863 _root_cl->do_oop(p); 2864 2865 if (!G1VerifyHeapRegionCodeRoots) { 2866 // We're not verifying the code roots attached to heap region. 2867 return; 2868 } 2869 2870 // Don't check the code roots during marking verification in a full GC 2871 if (_vo == VerifyOption_G1UseMarkWord) { 2872 return; 2873 } 2874 2875 // Now verify that the current nmethod (which contains p) is 2876 // in the code root list of the heap region containing the 2877 // object referenced by p. 2878 2879 T heap_oop = oopDesc::load_heap_oop(p); 2880 if (!oopDesc::is_null(heap_oop)) { 2881 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2882 2883 // Now fetch the region containing the object 2884 HeapRegion* hr = _g1h->heap_region_containing(obj); 2885 HeapRegionRemSet* hrrs = hr->rem_set(); 2886 // Verify that the strong code root list for this region 2887 // contains the nmethod 2888 if (!hrrs->strong_code_roots_list_contains(_nm)) { 2889 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " " 2890 "from nmethod " PTR_FORMAT " not in strong " 2891 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")", 2892 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end())); 2893 _failures = true; 2894 } 2895 } 2896 } 2897 2898 public: 2899 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 2900 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 2901 2902 void do_oop(oop* p) { do_oop_work(p); } 2903 void do_oop(narrowOop* p) { do_oop_work(p); } 2904 2905 void set_nmethod(nmethod* nm) { _nm = nm; } 2906 bool failures() { return _failures; } 2907 }; 2908 2909 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 2910 G1VerifyCodeRootOopClosure* _oop_cl; 2911 2912 public: 2913 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 2914 _oop_cl(oop_cl) {} 2915 2916 void do_code_blob(CodeBlob* cb) { 2917 nmethod* nm = cb->as_nmethod_or_null(); 2918 if (nm != NULL) { 2919 _oop_cl->set_nmethod(nm); 2920 nm->oops_do(_oop_cl); 2921 } 2922 } 2923 }; 2924 2925 class YoungRefCounterClosure : public OopClosure { 2926 G1CollectedHeap* _g1h; 2927 int _count; 2928 public: 2929 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 2930 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 2931 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 2932 2933 int count() { return _count; } 2934 void reset_count() { _count = 0; }; 2935 }; 2936 2937 class VerifyKlassClosure: public KlassClosure { 2938 YoungRefCounterClosure _young_ref_counter_closure; 2939 OopClosure *_oop_closure; 2940 public: 2941 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 2942 void do_klass(Klass* k) { 2943 k->oops_do(_oop_closure); 2944 2945 _young_ref_counter_closure.reset_count(); 2946 k->oops_do(&_young_ref_counter_closure); 2947 if (_young_ref_counter_closure.count() > 0) { 2948 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)); 2949 } 2950 } 2951 }; 2952 2953 class VerifyLivenessOopClosure: public OopClosure { 2954 G1CollectedHeap* _g1h; 2955 VerifyOption _vo; 2956 public: 2957 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 2958 _g1h(g1h), _vo(vo) 2959 { } 2960 void do_oop(narrowOop *p) { do_oop_work(p); } 2961 void do_oop( oop *p) { do_oop_work(p); } 2962 2963 template <class T> void do_oop_work(T *p) { 2964 oop obj = oopDesc::load_decode_heap_oop(p); 2965 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 2966 "Dead object referenced by a not dead object"); 2967 } 2968 }; 2969 2970 class VerifyObjsInRegionClosure: public ObjectClosure { 2971 private: 2972 G1CollectedHeap* _g1h; 2973 size_t _live_bytes; 2974 HeapRegion *_hr; 2975 VerifyOption _vo; 2976 public: 2977 // _vo == UsePrevMarking -> use "prev" marking information, 2978 // _vo == UseNextMarking -> use "next" marking information, 2979 // _vo == UseMarkWord -> use mark word from object header. 2980 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 2981 : _live_bytes(0), _hr(hr), _vo(vo) { 2982 _g1h = G1CollectedHeap::heap(); 2983 } 2984 void do_object(oop o) { 2985 VerifyLivenessOopClosure isLive(_g1h, _vo); 2986 assert(o != NULL, "Huh?"); 2987 if (!_g1h->is_obj_dead_cond(o, _vo)) { 2988 // If the object is alive according to the mark word, 2989 // then verify that the marking information agrees. 2990 // Note we can't verify the contra-positive of the 2991 // above: if the object is dead (according to the mark 2992 // word), it may not be marked, or may have been marked 2993 // but has since became dead, or may have been allocated 2994 // since the last marking. 2995 if (_vo == VerifyOption_G1UseMarkWord) { 2996 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 2997 } 2998 2999 o->oop_iterate_no_header(&isLive); 3000 if (!_hr->obj_allocated_since_prev_marking(o)) { 3001 size_t obj_size = o->size(); // Make sure we don't overflow 3002 _live_bytes += (obj_size * HeapWordSize); 3003 } 3004 } 3005 } 3006 size_t live_bytes() { return _live_bytes; } 3007 }; 3008 3009 class VerifyArchiveOopClosure: public OopClosure { 3010 public: 3011 VerifyArchiveOopClosure(HeapRegion *hr) { } 3012 void do_oop(narrowOop *p) { do_oop_work(p); } 3013 void do_oop( oop *p) { do_oop_work(p); } 3014 3015 template <class T> void do_oop_work(T *p) { 3016 oop obj = oopDesc::load_decode_heap_oop(p); 3017 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj), 3018 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT, 3019 p2i(p), p2i(obj)); 3020 } 3021 }; 3022 3023 class VerifyArchiveRegionClosure: public ObjectClosure { 3024 public: 3025 VerifyArchiveRegionClosure(HeapRegion *hr) { } 3026 // Verify that all object pointers are to archive regions. 3027 void do_object(oop o) { 3028 VerifyArchiveOopClosure checkOop(NULL); 3029 assert(o != NULL, "Should not be here for NULL oops"); 3030 o->oop_iterate_no_header(&checkOop); 3031 } 3032 }; 3033 3034 class VerifyRegionClosure: public HeapRegionClosure { 3035 private: 3036 bool _par; 3037 VerifyOption _vo; 3038 bool _failures; 3039 public: 3040 // _vo == UsePrevMarking -> use "prev" marking information, 3041 // _vo == UseNextMarking -> use "next" marking information, 3042 // _vo == UseMarkWord -> use mark word from object header. 3043 VerifyRegionClosure(bool par, VerifyOption vo) 3044 : _par(par), 3045 _vo(vo), 3046 _failures(false) {} 3047 3048 bool failures() { 3049 return _failures; 3050 } 3051 3052 bool doHeapRegion(HeapRegion* r) { 3053 // For archive regions, verify there are no heap pointers to 3054 // non-pinned regions. For all others, verify liveness info. 3055 if (r->is_archive()) { 3056 VerifyArchiveRegionClosure verify_oop_pointers(r); 3057 r->object_iterate(&verify_oop_pointers); 3058 return true; 3059 } 3060 if (!r->is_continues_humongous()) { 3061 bool failures = false; 3062 r->verify(_vo, &failures); 3063 if (failures) { 3064 _failures = true; 3065 } else { 3066 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3067 r->object_iterate(¬_dead_yet_cl); 3068 if (_vo != VerifyOption_G1UseNextMarking) { 3069 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3070 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] " 3071 "max_live_bytes " SIZE_FORMAT " " 3072 "< calculated " SIZE_FORMAT, 3073 p2i(r->bottom()), p2i(r->end()), 3074 r->max_live_bytes(), 3075 not_dead_yet_cl.live_bytes()); 3076 _failures = true; 3077 } 3078 } else { 3079 // When vo == UseNextMarking we cannot currently do a sanity 3080 // check on the live bytes as the calculation has not been 3081 // finalized yet. 3082 } 3083 } 3084 } 3085 return false; // stop the region iteration if we hit a failure 3086 } 3087 }; 3088 3089 // This is the task used for parallel verification of the heap regions 3090 3091 class G1ParVerifyTask: public AbstractGangTask { 3092 private: 3093 G1CollectedHeap* _g1h; 3094 VerifyOption _vo; 3095 bool _failures; 3096 HeapRegionClaimer _hrclaimer; 3097 3098 public: 3099 // _vo == UsePrevMarking -> use "prev" marking information, 3100 // _vo == UseNextMarking -> use "next" marking information, 3101 // _vo == UseMarkWord -> use mark word from object header. 3102 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3103 AbstractGangTask("Parallel verify task"), 3104 _g1h(g1h), 3105 _vo(vo), 3106 _failures(false), 3107 _hrclaimer(g1h->workers()->active_workers()) {} 3108 3109 bool failures() { 3110 return _failures; 3111 } 3112 3113 void work(uint worker_id) { 3114 HandleMark hm; 3115 VerifyRegionClosure blk(true, _vo); 3116 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer); 3117 if (blk.failures()) { 3118 _failures = true; 3119 } 3120 } 3121 }; 3122 3123 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3124 if (SafepointSynchronize::is_at_safepoint()) { 3125 assert(Thread::current()->is_VM_thread(), 3126 "Expected to be executed serially by the VM thread at this point"); 3127 3128 if (!silent) { gclog_or_tty->print("Roots "); } 3129 VerifyRootsClosure rootsCl(vo); 3130 VerifyKlassClosure klassCl(this, &rootsCl); 3131 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3132 3133 // We apply the relevant closures to all the oops in the 3134 // system dictionary, class loader data graph, the string table 3135 // and the nmethods in the code cache. 3136 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3137 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3138 3139 { 3140 G1RootProcessor root_processor(this, 1); 3141 root_processor.process_all_roots(&rootsCl, 3142 &cldCl, 3143 &blobsCl); 3144 } 3145 3146 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3147 3148 if (vo != VerifyOption_G1UseMarkWord) { 3149 // If we're verifying during a full GC then the region sets 3150 // will have been torn down at the start of the GC. Therefore 3151 // verifying the region sets will fail. So we only verify 3152 // the region sets when not in a full GC. 3153 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3154 verify_region_sets(); 3155 } 3156 3157 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3158 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3159 3160 G1ParVerifyTask task(this, vo); 3161 workers()->run_task(&task); 3162 if (task.failures()) { 3163 failures = true; 3164 } 3165 3166 } else { 3167 VerifyRegionClosure blk(false, vo); 3168 heap_region_iterate(&blk); 3169 if (blk.failures()) { 3170 failures = true; 3171 } 3172 } 3173 3174 if (G1StringDedup::is_enabled()) { 3175 if (!silent) gclog_or_tty->print("StrDedup "); 3176 G1StringDedup::verify(); 3177 } 3178 3179 if (failures) { 3180 gclog_or_tty->print_cr("Heap:"); 3181 // It helps to have the per-region information in the output to 3182 // help us track down what went wrong. This is why we call 3183 // print_extended_on() instead of print_on(). 3184 print_extended_on(gclog_or_tty); 3185 gclog_or_tty->cr(); 3186 gclog_or_tty->flush(); 3187 } 3188 guarantee(!failures, "there should not have been any failures"); 3189 } else { 3190 if (!silent) { 3191 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3192 if (G1StringDedup::is_enabled()) { 3193 gclog_or_tty->print(", StrDedup"); 3194 } 3195 gclog_or_tty->print(") "); 3196 } 3197 } 3198 } 3199 3200 void G1CollectedHeap::verify(bool silent) { 3201 verify(silent, VerifyOption_G1UsePrevMarking); 3202 } 3203 3204 double G1CollectedHeap::verify(bool guard, const char* msg) { 3205 double verify_time_ms = 0.0; 3206 3207 if (guard && total_collections() >= VerifyGCStartAt) { 3208 double verify_start = os::elapsedTime(); 3209 HandleMark hm; // Discard invalid handles created during verification 3210 prepare_for_verify(); 3211 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3212 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3213 } 3214 3215 return verify_time_ms; 3216 } 3217 3218 void G1CollectedHeap::verify_before_gc() { 3219 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3220 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3221 } 3222 3223 void G1CollectedHeap::verify_after_gc() { 3224 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3225 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3226 } 3227 3228 class PrintRegionClosure: public HeapRegionClosure { 3229 outputStream* _st; 3230 public: 3231 PrintRegionClosure(outputStream* st) : _st(st) {} 3232 bool doHeapRegion(HeapRegion* r) { 3233 r->print_on(_st); 3234 return false; 3235 } 3236 }; 3237 3238 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3239 const HeapRegion* hr, 3240 const VerifyOption vo) const { 3241 switch (vo) { 3242 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3243 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3244 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive(); 3245 default: ShouldNotReachHere(); 3246 } 3247 return false; // keep some compilers happy 3248 } 3249 3250 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3251 const VerifyOption vo) const { 3252 switch (vo) { 3253 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3254 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3255 case VerifyOption_G1UseMarkWord: { 3256 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj); 3257 return !obj->is_gc_marked() && !hr->is_archive(); 3258 } 3259 default: ShouldNotReachHere(); 3260 } 3261 return false; // keep some compilers happy 3262 } 3263 3264 void G1CollectedHeap::print_on(outputStream* st) const { 3265 st->print(" %-20s", "garbage-first heap"); 3266 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3267 capacity()/K, used_unlocked()/K); 3268 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")", 3269 p2i(_hrm.reserved().start()), 3270 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords), 3271 p2i(_hrm.reserved().end())); 3272 st->cr(); 3273 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3274 uint young_regions = _young_list->length(); 3275 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3276 (size_t) young_regions * HeapRegion::GrainBytes / K); 3277 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3278 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3279 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3280 st->cr(); 3281 MetaspaceAux::print_on(st); 3282 } 3283 3284 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3285 print_on(st); 3286 3287 // Print the per-region information. 3288 st->cr(); 3289 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, " 3290 "HS=humongous(starts), HC=humongous(continues), " 3291 "CS=collection set, F=free, A=archive, TS=gc time stamp, " 3292 "PTAMS=previous top-at-mark-start, " 3293 "NTAMS=next top-at-mark-start)"); 3294 PrintRegionClosure blk(st); 3295 heap_region_iterate(&blk); 3296 } 3297 3298 void G1CollectedHeap::print_on_error(outputStream* st) const { 3299 this->CollectedHeap::print_on_error(st); 3300 3301 if (_cm != NULL) { 3302 st->cr(); 3303 _cm->print_on_error(st); 3304 } 3305 } 3306 3307 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3308 workers()->print_worker_threads_on(st); 3309 _cmThread->print_on(st); 3310 st->cr(); 3311 _cm->print_worker_threads_on(st); 3312 _cg1r->print_worker_threads_on(st); 3313 if (G1StringDedup::is_enabled()) { 3314 G1StringDedup::print_worker_threads_on(st); 3315 } 3316 } 3317 3318 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3319 workers()->threads_do(tc); 3320 tc->do_thread(_cmThread); 3321 _cg1r->threads_do(tc); 3322 if (G1StringDedup::is_enabled()) { 3323 G1StringDedup::threads_do(tc); 3324 } 3325 } 3326 3327 void G1CollectedHeap::print_tracing_info() const { 3328 // We'll overload this to mean "trace GC pause statistics." 3329 if (TraceYoungGenTime || TraceOldGenTime) { 3330 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3331 // to that. 3332 g1_policy()->print_tracing_info(); 3333 } 3334 if (G1SummarizeRSetStats) { 3335 g1_rem_set()->print_summary_info(); 3336 } 3337 if (G1SummarizeConcMark) { 3338 concurrent_mark()->print_summary_info(); 3339 } 3340 g1_policy()->print_yg_surv_rate_info(); 3341 } 3342 3343 #ifndef PRODUCT 3344 // Helpful for debugging RSet issues. 3345 3346 class PrintRSetsClosure : public HeapRegionClosure { 3347 private: 3348 const char* _msg; 3349 size_t _occupied_sum; 3350 3351 public: 3352 bool doHeapRegion(HeapRegion* r) { 3353 HeapRegionRemSet* hrrs = r->rem_set(); 3354 size_t occupied = hrrs->occupied(); 3355 _occupied_sum += occupied; 3356 3357 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT, 3358 HR_FORMAT_PARAMS(r)); 3359 if (occupied == 0) { 3360 gclog_or_tty->print_cr(" RSet is empty"); 3361 } else { 3362 hrrs->print(); 3363 } 3364 gclog_or_tty->print_cr("----------"); 3365 return false; 3366 } 3367 3368 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3369 gclog_or_tty->cr(); 3370 gclog_or_tty->print_cr("========================================"); 3371 gclog_or_tty->print_cr("%s", msg); 3372 gclog_or_tty->cr(); 3373 } 3374 3375 ~PrintRSetsClosure() { 3376 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 3377 gclog_or_tty->print_cr("========================================"); 3378 gclog_or_tty->cr(); 3379 } 3380 }; 3381 3382 void G1CollectedHeap::print_cset_rsets() { 3383 PrintRSetsClosure cl("Printing CSet RSets"); 3384 collection_set_iterate(&cl); 3385 } 3386 3387 void G1CollectedHeap::print_all_rsets() { 3388 PrintRSetsClosure cl("Printing All RSets");; 3389 heap_region_iterate(&cl); 3390 } 3391 #endif // PRODUCT 3392 3393 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 3394 YoungList* young_list = heap()->young_list(); 3395 3396 size_t eden_used_bytes = young_list->eden_used_bytes(); 3397 size_t survivor_used_bytes = young_list->survivor_used_bytes(); 3398 3399 size_t eden_capacity_bytes = 3400 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 3401 3402 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 3403 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes); 3404 } 3405 3406 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 3407 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 3408 stats->unused(), stats->used(), stats->region_end_waste(), 3409 stats->regions_filled(), stats->direct_allocated(), 3410 stats->failure_used(), stats->failure_waste()); 3411 } 3412 3413 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 3414 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 3415 gc_tracer->report_gc_heap_summary(when, heap_summary); 3416 3417 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 3418 gc_tracer->report_metaspace_summary(when, metaspace_summary); 3419 } 3420 3421 3422 G1CollectedHeap* G1CollectedHeap::heap() { 3423 CollectedHeap* heap = Universe::heap(); 3424 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 3425 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); 3426 return (G1CollectedHeap*)heap; 3427 } 3428 3429 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3430 // always_do_update_barrier = false; 3431 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3432 // Fill TLAB's and such 3433 accumulate_statistics_all_tlabs(); 3434 ensure_parsability(true); 3435 3436 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3437 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3438 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3439 } 3440 } 3441 3442 void G1CollectedHeap::gc_epilogue(bool full) { 3443 3444 if (G1SummarizeRSetStats && 3445 (G1SummarizeRSetStatsPeriod > 0) && 3446 // we are at the end of the GC. Total collections has already been increased. 3447 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3448 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3449 } 3450 3451 // FIXME: what is this about? 3452 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3453 // is set. 3454 #if defined(COMPILER2) || INCLUDE_JVMCI 3455 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 3456 #endif 3457 // always_do_update_barrier = true; 3458 3459 resize_all_tlabs(); 3460 allocation_context_stats().update(full); 3461 3462 // We have just completed a GC. Update the soft reference 3463 // policy with the new heap occupancy 3464 Universe::update_heap_info_at_gc(); 3465 } 3466 3467 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3468 uint gc_count_before, 3469 bool* succeeded, 3470 GCCause::Cause gc_cause) { 3471 assert_heap_not_locked_and_not_at_safepoint(); 3472 g1_policy()->record_stop_world_start(); 3473 VM_G1IncCollectionPause op(gc_count_before, 3474 word_size, 3475 false, /* should_initiate_conc_mark */ 3476 g1_policy()->max_pause_time_ms(), 3477 gc_cause); 3478 3479 op.set_allocation_context(AllocationContext::current()); 3480 VMThread::execute(&op); 3481 3482 HeapWord* result = op.result(); 3483 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3484 assert(result == NULL || ret_succeeded, 3485 "the result should be NULL if the VM did not succeed"); 3486 *succeeded = ret_succeeded; 3487 3488 assert_heap_not_locked(); 3489 return result; 3490 } 3491 3492 void 3493 G1CollectedHeap::doConcurrentMark() { 3494 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3495 if (!_cmThread->in_progress()) { 3496 _cmThread->set_started(); 3497 CGC_lock->notify(); 3498 } 3499 } 3500 3501 size_t G1CollectedHeap::pending_card_num() { 3502 size_t extra_cards = 0; 3503 JavaThread *curr = Threads::first(); 3504 while (curr != NULL) { 3505 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3506 extra_cards += dcq.size(); 3507 curr = curr->next(); 3508 } 3509 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3510 size_t buffer_size = dcqs.buffer_size(); 3511 size_t buffer_num = dcqs.completed_buffers_num(); 3512 3513 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3514 // in bytes - not the number of 'entries'. We need to convert 3515 // into a number of cards. 3516 return (buffer_size * buffer_num + extra_cards) / oopSize; 3517 } 3518 3519 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3520 private: 3521 size_t _total_humongous; 3522 size_t _candidate_humongous; 3523 3524 DirtyCardQueue _dcq; 3525 3526 // We don't nominate objects with many remembered set entries, on 3527 // the assumption that such objects are likely still live. 3528 bool is_remset_small(HeapRegion* region) const { 3529 HeapRegionRemSet* const rset = region->rem_set(); 3530 return G1EagerReclaimHumongousObjectsWithStaleRefs 3531 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) 3532 : rset->is_empty(); 3533 } 3534 3535 bool is_typeArray_region(HeapRegion* region) const { 3536 return oop(region->bottom())->is_typeArray(); 3537 } 3538 3539 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { 3540 assert(region->is_starts_humongous(), "Must start a humongous object"); 3541 3542 // Candidate selection must satisfy the following constraints 3543 // while concurrent marking is in progress: 3544 // 3545 // * In order to maintain SATB invariants, an object must not be 3546 // reclaimed if it was allocated before the start of marking and 3547 // has not had its references scanned. Such an object must have 3548 // its references (including type metadata) scanned to ensure no 3549 // live objects are missed by the marking process. Objects 3550 // allocated after the start of concurrent marking don't need to 3551 // be scanned. 3552 // 3553 // * An object must not be reclaimed if it is on the concurrent 3554 // mark stack. Objects allocated after the start of concurrent 3555 // marking are never pushed on the mark stack. 3556 // 3557 // Nominating only objects allocated after the start of concurrent 3558 // marking is sufficient to meet both constraints. This may miss 3559 // some objects that satisfy the constraints, but the marking data 3560 // structures don't support efficiently performing the needed 3561 // additional tests or scrubbing of the mark stack. 3562 // 3563 // However, we presently only nominate is_typeArray() objects. 3564 // A humongous object containing references induces remembered 3565 // set entries on other regions. In order to reclaim such an 3566 // object, those remembered sets would need to be cleaned up. 3567 // 3568 // We also treat is_typeArray() objects specially, allowing them 3569 // to be reclaimed even if allocated before the start of 3570 // concurrent mark. For this we rely on mark stack insertion to 3571 // exclude is_typeArray() objects, preventing reclaiming an object 3572 // that is in the mark stack. We also rely on the metadata for 3573 // such objects to be built-in and so ensured to be kept live. 3574 // Frequent allocation and drop of large binary blobs is an 3575 // important use case for eager reclaim, and this special handling 3576 // may reduce needed headroom. 3577 3578 return is_typeArray_region(region) && is_remset_small(region); 3579 } 3580 3581 public: 3582 RegisterHumongousWithInCSetFastTestClosure() 3583 : _total_humongous(0), 3584 _candidate_humongous(0), 3585 _dcq(&JavaThread::dirty_card_queue_set()) { 3586 } 3587 3588 virtual bool doHeapRegion(HeapRegion* r) { 3589 if (!r->is_starts_humongous()) { 3590 return false; 3591 } 3592 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3593 3594 bool is_candidate = humongous_region_is_candidate(g1h, r); 3595 uint rindex = r->hrm_index(); 3596 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 3597 if (is_candidate) { 3598 _candidate_humongous++; 3599 g1h->register_humongous_region_with_cset(rindex); 3600 // Is_candidate already filters out humongous object with large remembered sets. 3601 // If we have a humongous object with a few remembered sets, we simply flush these 3602 // remembered set entries into the DCQS. That will result in automatic 3603 // re-evaluation of their remembered set entries during the following evacuation 3604 // phase. 3605 if (!r->rem_set()->is_empty()) { 3606 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 3607 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 3608 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 3609 HeapRegionRemSetIterator hrrs(r->rem_set()); 3610 size_t card_index; 3611 while (hrrs.has_next(card_index)) { 3612 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 3613 // The remembered set might contain references to already freed 3614 // regions. Filter out such entries to avoid failing card table 3615 // verification. 3616 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) { 3617 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 3618 *card_ptr = CardTableModRefBS::dirty_card_val(); 3619 _dcq.enqueue(card_ptr); 3620 } 3621 } 3622 } 3623 r->rem_set()->clear_locked(); 3624 } 3625 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 3626 } 3627 _total_humongous++; 3628 3629 return false; 3630 } 3631 3632 size_t total_humongous() const { return _total_humongous; } 3633 size_t candidate_humongous() const { return _candidate_humongous; } 3634 3635 void flush_rem_set_entries() { _dcq.flush(); } 3636 }; 3637 3638 void G1CollectedHeap::register_humongous_regions_with_cset() { 3639 if (!G1EagerReclaimHumongousObjects) { 3640 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 3641 return; 3642 } 3643 double time = os::elapsed_counter(); 3644 3645 // Collect reclaim candidate information and register candidates with cset. 3646 RegisterHumongousWithInCSetFastTestClosure cl; 3647 heap_region_iterate(&cl); 3648 3649 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 3650 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 3651 cl.total_humongous(), 3652 cl.candidate_humongous()); 3653 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3654 3655 // Finally flush all remembered set entries to re-check into the global DCQS. 3656 cl.flush_rem_set_entries(); 3657 } 3658 3659 #ifdef ASSERT 3660 class VerifyCSetClosure: public HeapRegionClosure { 3661 public: 3662 bool doHeapRegion(HeapRegion* hr) { 3663 // Here we check that the CSet region's RSet is ready for parallel 3664 // iteration. The fields that we'll verify are only manipulated 3665 // when the region is part of a CSet and is collected. Afterwards, 3666 // we reset these fields when we clear the region's RSet (when the 3667 // region is freed) so they are ready when the region is 3668 // re-allocated. The only exception to this is if there's an 3669 // evacuation failure and instead of freeing the region we leave 3670 // it in the heap. In that case, we reset these fields during 3671 // evacuation failure handling. 3672 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3673 3674 // Here's a good place to add any other checks we'd like to 3675 // perform on CSet regions. 3676 return false; 3677 } 3678 }; 3679 #endif // ASSERT 3680 3681 uint G1CollectedHeap::num_task_queues() const { 3682 return _task_queues->size(); 3683 } 3684 3685 #if TASKQUEUE_STATS 3686 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3687 st->print_raw_cr("GC Task Stats"); 3688 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3689 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3690 } 3691 3692 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3693 print_taskqueue_stats_hdr(st); 3694 3695 TaskQueueStats totals; 3696 const uint n = num_task_queues(); 3697 for (uint i = 0; i < n; ++i) { 3698 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 3699 totals += task_queue(i)->stats; 3700 } 3701 st->print_raw("tot "); totals.print(st); st->cr(); 3702 3703 DEBUG_ONLY(totals.verify()); 3704 } 3705 3706 void G1CollectedHeap::reset_taskqueue_stats() { 3707 const uint n = num_task_queues(); 3708 for (uint i = 0; i < n; ++i) { 3709 task_queue(i)->stats.reset(); 3710 } 3711 } 3712 #endif // TASKQUEUE_STATS 3713 3714 void G1CollectedHeap::log_gc_header() { 3715 if (!G1Log::fine()) { 3716 return; 3717 } 3718 3719 gclog_or_tty->gclog_stamp(); 3720 3721 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3722 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)") 3723 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3724 3725 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3726 } 3727 3728 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3729 if (!G1Log::fine()) { 3730 return; 3731 } 3732 3733 if (G1Log::finer()) { 3734 if (evacuation_failed()) { 3735 gclog_or_tty->print(" (to-space exhausted)"); 3736 } 3737 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3738 g1_policy()->print_phases(pause_time_sec); 3739 g1_policy()->print_detailed_heap_transition(); 3740 } else { 3741 if (evacuation_failed()) { 3742 gclog_or_tty->print("--"); 3743 } 3744 g1_policy()->print_heap_transition(); 3745 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3746 } 3747 gclog_or_tty->flush(); 3748 } 3749 3750 void G1CollectedHeap::wait_for_root_region_scanning() { 3751 double scan_wait_start = os::elapsedTime(); 3752 // We have to wait until the CM threads finish scanning the 3753 // root regions as it's the only way to ensure that all the 3754 // objects on them have been correctly scanned before we start 3755 // moving them during the GC. 3756 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3757 double wait_time_ms = 0.0; 3758 if (waited) { 3759 double scan_wait_end = os::elapsedTime(); 3760 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3761 } 3762 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3763 } 3764 3765 bool 3766 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3767 assert_at_safepoint(true /* should_be_vm_thread */); 3768 guarantee(!is_gc_active(), "collection is not reentrant"); 3769 3770 if (GC_locker::check_active_before_gc()) { 3771 return false; 3772 } 3773 3774 _gc_timer_stw->register_gc_start(); 3775 3776 GCIdMark gc_id_mark; 3777 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3778 3779 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3780 ResourceMark rm; 3781 3782 wait_for_root_region_scanning(); 3783 3784 G1Log::update_level(); 3785 print_heap_before_gc(); 3786 trace_heap_before_gc(_gc_tracer_stw); 3787 3788 verify_region_sets_optional(); 3789 verify_dirty_young_regions(); 3790 3791 // This call will decide whether this pause is an initial-mark 3792 // pause. If it is, during_initial_mark_pause() will return true 3793 // for the duration of this pause. 3794 g1_policy()->decide_on_conc_mark_initiation(); 3795 3796 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3797 assert(!collector_state()->during_initial_mark_pause() || 3798 collector_state()->gcs_are_young(), "sanity"); 3799 3800 // We also do not allow mixed GCs during marking. 3801 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity"); 3802 3803 // Record whether this pause is an initial mark. When the current 3804 // thread has completed its logging output and it's safe to signal 3805 // the CM thread, the flag's value in the policy has been reset. 3806 bool should_start_conc_mark = collector_state()->during_initial_mark_pause(); 3807 3808 // Inner scope for scope based logging, timers, and stats collection 3809 { 3810 EvacuationInfo evacuation_info; 3811 3812 if (collector_state()->during_initial_mark_pause()) { 3813 // We are about to start a marking cycle, so we increment the 3814 // full collection counter. 3815 increment_old_marking_cycles_started(); 3816 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3817 } 3818 3819 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 3820 3821 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3822 3823 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 3824 workers()->active_workers(), 3825 Threads::number_of_non_daemon_threads()); 3826 workers()->set_active_workers(active_workers); 3827 3828 double pause_start_sec = os::elapsedTime(); 3829 g1_policy()->note_gc_start(active_workers); 3830 log_gc_header(); 3831 3832 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3833 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3834 3835 // If the secondary_free_list is not empty, append it to the 3836 // free_list. No need to wait for the cleanup operation to finish; 3837 // the region allocation code will check the secondary_free_list 3838 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3839 // set, skip this step so that the region allocation code has to 3840 // get entries from the secondary_free_list. 3841 if (!G1StressConcRegionFreeing) { 3842 append_secondary_free_list_if_not_empty_with_lock(); 3843 } 3844 3845 assert(check_young_list_well_formed(), "young list should be well formed"); 3846 3847 // Don't dynamically change the number of GC threads this early. A value of 3848 // 0 is used to indicate serial work. When parallel work is done, 3849 // it will be set. 3850 3851 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3852 IsGCActiveMark x; 3853 3854 gc_prologue(false); 3855 increment_total_collections(false /* full gc */); 3856 increment_gc_time_stamp(); 3857 3858 verify_before_gc(); 3859 3860 check_bitmaps("GC Start"); 3861 3862 #if defined(COMPILER2) || INCLUDE_JVMCI 3863 DerivedPointerTable::clear(); 3864 #endif 3865 3866 // Please see comment in g1CollectedHeap.hpp and 3867 // G1CollectedHeap::ref_processing_init() to see how 3868 // reference processing currently works in G1. 3869 3870 // Enable discovery in the STW reference processor 3871 ref_processor_stw()->enable_discovery(); 3872 3873 { 3874 // We want to temporarily turn off discovery by the 3875 // CM ref processor, if necessary, and turn it back on 3876 // on again later if we do. Using a scoped 3877 // NoRefDiscovery object will do this. 3878 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3879 3880 // Forget the current alloc region (we might even choose it to be part 3881 // of the collection set!). 3882 _allocator->release_mutator_alloc_region(); 3883 3884 // We should call this after we retire the mutator alloc 3885 // region(s) so that all the ALLOC / RETIRE events are generated 3886 // before the start GC event. 3887 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3888 3889 // This timing is only used by the ergonomics to handle our pause target. 3890 // It is unclear why this should not include the full pause. We will 3891 // investigate this in CR 7178365. 3892 // 3893 // Preserving the old comment here if that helps the investigation: 3894 // 3895 // The elapsed time induced by the start time below deliberately elides 3896 // the possible verification above. 3897 double sample_start_time_sec = os::elapsedTime(); 3898 3899 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3900 3901 if (collector_state()->during_initial_mark_pause()) { 3902 concurrent_mark()->checkpointRootsInitialPre(); 3903 } 3904 3905 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms); 3906 g1_policy()->finalize_old_cset_part(time_remaining_ms); 3907 3908 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length()); 3909 3910 register_humongous_regions_with_cset(); 3911 3912 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3913 3914 _cm->note_start_of_gc(); 3915 // We call this after finalize_cset() to 3916 // ensure that the CSet has been finalized. 3917 _cm->verify_no_cset_oops(); 3918 3919 if (_hr_printer.is_active()) { 3920 HeapRegion* hr = g1_policy()->collection_set(); 3921 while (hr != NULL) { 3922 _hr_printer.cset(hr); 3923 hr = hr->next_in_collection_set(); 3924 } 3925 } 3926 3927 #ifdef ASSERT 3928 VerifyCSetClosure cl; 3929 collection_set_iterate(&cl); 3930 #endif // ASSERT 3931 3932 // Initialize the GC alloc regions. 3933 _allocator->init_gc_alloc_regions(evacuation_info); 3934 3935 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length()); 3936 pre_evacuate_collection_set(); 3937 3938 // Actually do the work... 3939 evacuate_collection_set(evacuation_info, &per_thread_states); 3940 3941 post_evacuate_collection_set(evacuation_info, &per_thread_states); 3942 3943 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 3944 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words); 3945 3946 eagerly_reclaim_humongous_regions(); 3947 3948 g1_policy()->clear_collection_set(); 3949 3950 // Start a new incremental collection set for the next pause. 3951 g1_policy()->start_incremental_cset_building(); 3952 3953 clear_cset_fast_test(); 3954 3955 _young_list->reset_sampled_info(); 3956 3957 // Don't check the whole heap at this point as the 3958 // GC alloc regions from this pause have been tagged 3959 // as survivors and moved on to the survivor list. 3960 // Survivor regions will fail the !is_young() check. 3961 assert(check_young_list_empty(false /* check_heap */), 3962 "young list should be empty"); 3963 3964 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 3965 _young_list->first_survivor_region(), 3966 _young_list->last_survivor_region()); 3967 3968 _young_list->reset_auxilary_lists(); 3969 3970 if (evacuation_failed()) { 3971 set_used(recalculate_used()); 3972 if (_archive_allocator != NULL) { 3973 _archive_allocator->clear_used(); 3974 } 3975 for (uint i = 0; i < ParallelGCThreads; i++) { 3976 if (_evacuation_failed_info_array[i].has_failed()) { 3977 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3978 } 3979 } 3980 } else { 3981 // The "used" of the the collection set have already been subtracted 3982 // when they were freed. Add in the bytes evacuated. 3983 increase_used(g1_policy()->bytes_copied_during_gc()); 3984 } 3985 3986 if (collector_state()->during_initial_mark_pause()) { 3987 // We have to do this before we notify the CM threads that 3988 // they can start working to make sure that all the 3989 // appropriate initialization is done on the CM object. 3990 concurrent_mark()->checkpointRootsInitialPost(); 3991 collector_state()->set_mark_in_progress(true); 3992 // Note that we don't actually trigger the CM thread at 3993 // this point. We do that later when we're sure that 3994 // the current thread has completed its logging output. 3995 } 3996 3997 allocate_dummy_regions(); 3998 3999 _allocator->init_mutator_alloc_region(); 4000 4001 { 4002 size_t expand_bytes = g1_policy()->expansion_amount(); 4003 if (expand_bytes > 0) { 4004 size_t bytes_before = capacity(); 4005 // No need for an ergo verbose message here, 4006 // expansion_amount() does this when it returns a value > 0. 4007 double expand_ms; 4008 if (!expand(expand_bytes, &expand_ms)) { 4009 // We failed to expand the heap. Cannot do anything about it. 4010 } 4011 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 4012 } 4013 } 4014 4015 // We redo the verification but now wrt to the new CSet which 4016 // has just got initialized after the previous CSet was freed. 4017 _cm->verify_no_cset_oops(); 4018 _cm->note_end_of_gc(); 4019 4020 // This timing is only used by the ergonomics to handle our pause target. 4021 // It is unclear why this should not include the full pause. We will 4022 // investigate this in CR 7178365. 4023 double sample_end_time_sec = os::elapsedTime(); 4024 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 4025 size_t total_cards_scanned = per_thread_states.total_cards_scanned(); 4026 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned); 4027 4028 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before()); 4029 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 4030 4031 MemoryService::track_memory_usage(); 4032 4033 // In prepare_for_verify() below we'll need to scan the deferred 4034 // update buffers to bring the RSets up-to-date if 4035 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4036 // the update buffers we'll probably need to scan cards on the 4037 // regions we just allocated to (i.e., the GC alloc 4038 // regions). However, during the last GC we called 4039 // set_saved_mark() on all the GC alloc regions, so card 4040 // scanning might skip the [saved_mark_word()...top()] area of 4041 // those regions (i.e., the area we allocated objects into 4042 // during the last GC). But it shouldn't. Given that 4043 // saved_mark_word() is conditional on whether the GC time stamp 4044 // on the region is current or not, by incrementing the GC time 4045 // stamp here we invalidate all the GC time stamps on all the 4046 // regions and saved_mark_word() will simply return top() for 4047 // all the regions. This is a nicer way of ensuring this rather 4048 // than iterating over the regions and fixing them. In fact, the 4049 // GC time stamp increment here also ensures that 4050 // saved_mark_word() will return top() between pauses, i.e., 4051 // during concurrent refinement. So we don't need the 4052 // is_gc_active() check to decided which top to use when 4053 // scanning cards (see CR 7039627). 4054 increment_gc_time_stamp(); 4055 4056 verify_after_gc(); 4057 check_bitmaps("GC End"); 4058 4059 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4060 ref_processor_stw()->verify_no_references_recorded(); 4061 4062 // CM reference discovery will be re-enabled if necessary. 4063 } 4064 4065 // We should do this after we potentially expand the heap so 4066 // that all the COMMIT events are generated before the end GC 4067 // event, and after we retire the GC alloc regions so that all 4068 // RETIRE events are generated before the end GC event. 4069 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4070 4071 #ifdef TRACESPINNING 4072 ParallelTaskTerminator::print_termination_counts(); 4073 #endif 4074 4075 gc_epilogue(false); 4076 } 4077 4078 // Print the remainder of the GC log output. 4079 log_gc_footer(os::elapsedTime() - pause_start_sec); 4080 4081 // It is not yet to safe to tell the concurrent mark to 4082 // start as we have some optional output below. We don't want the 4083 // output from the concurrent mark thread interfering with this 4084 // logging output either. 4085 4086 _hrm.verify_optional(); 4087 verify_region_sets_optional(); 4088 4089 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats()); 4090 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4091 4092 print_heap_after_gc(); 4093 trace_heap_after_gc(_gc_tracer_stw); 4094 4095 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4096 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4097 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4098 // before any GC notifications are raised. 4099 g1mm()->update_sizes(); 4100 4101 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4102 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4103 _gc_timer_stw->register_gc_end(); 4104 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4105 } 4106 // It should now be safe to tell the concurrent mark thread to start 4107 // without its logging output interfering with the logging output 4108 // that came from the pause. 4109 4110 if (should_start_conc_mark) { 4111 // CAUTION: after the doConcurrentMark() call below, 4112 // the concurrent marking thread(s) could be running 4113 // concurrently with us. Make sure that anything after 4114 // this point does not assume that we are the only GC thread 4115 // running. Note: of course, the actual marking work will 4116 // not start until the safepoint itself is released in 4117 // SuspendibleThreadSet::desynchronize(). 4118 doConcurrentMark(); 4119 } 4120 4121 return true; 4122 } 4123 4124 void G1CollectedHeap::remove_self_forwarding_pointers() { 4125 double remove_self_forwards_start = os::elapsedTime(); 4126 4127 G1ParRemoveSelfForwardPtrsTask rsfp_task; 4128 workers()->run_task(&rsfp_task); 4129 4130 // Now restore saved marks, if any. 4131 for (uint i = 0; i < ParallelGCThreads; i++) { 4132 OopAndMarkOopStack& cur = _preserved_objs[i]; 4133 while (!cur.is_empty()) { 4134 OopAndMarkOop elem = cur.pop(); 4135 elem.set_mark(); 4136 } 4137 cur.clear(true); 4138 } 4139 4140 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4141 } 4142 4143 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 4144 if (!_evacuation_failed) { 4145 _evacuation_failed = true; 4146 } 4147 4148 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 4149 4150 // We want to call the "for_promotion_failure" version only in the 4151 // case of a promotion failure. 4152 if (m->must_be_preserved_for_promotion_failure(obj)) { 4153 OopAndMarkOop elem(obj, m); 4154 _preserved_objs[worker_id].push(elem); 4155 } 4156 } 4157 4158 class G1ParEvacuateFollowersClosure : public VoidClosure { 4159 private: 4160 double _start_term; 4161 double _term_time; 4162 size_t _term_attempts; 4163 4164 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 4165 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 4166 protected: 4167 G1CollectedHeap* _g1h; 4168 G1ParScanThreadState* _par_scan_state; 4169 RefToScanQueueSet* _queues; 4170 ParallelTaskTerminator* _terminator; 4171 4172 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4173 RefToScanQueueSet* queues() { return _queues; } 4174 ParallelTaskTerminator* terminator() { return _terminator; } 4175 4176 public: 4177 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4178 G1ParScanThreadState* par_scan_state, 4179 RefToScanQueueSet* queues, 4180 ParallelTaskTerminator* terminator) 4181 : _g1h(g1h), _par_scan_state(par_scan_state), 4182 _queues(queues), _terminator(terminator), 4183 _start_term(0.0), _term_time(0.0), _term_attempts(0) {} 4184 4185 void do_void(); 4186 4187 double term_time() const { return _term_time; } 4188 size_t term_attempts() const { return _term_attempts; } 4189 4190 private: 4191 inline bool offer_termination(); 4192 }; 4193 4194 bool G1ParEvacuateFollowersClosure::offer_termination() { 4195 G1ParScanThreadState* const pss = par_scan_state(); 4196 start_term_time(); 4197 const bool res = terminator()->offer_termination(); 4198 end_term_time(); 4199 return res; 4200 } 4201 4202 void G1ParEvacuateFollowersClosure::do_void() { 4203 G1ParScanThreadState* const pss = par_scan_state(); 4204 pss->trim_queue(); 4205 do { 4206 pss->steal_and_trim_queue(queues()); 4207 } while (!offer_termination()); 4208 } 4209 4210 class G1ParTask : public AbstractGangTask { 4211 protected: 4212 G1CollectedHeap* _g1h; 4213 G1ParScanThreadStateSet* _pss; 4214 RefToScanQueueSet* _queues; 4215 G1RootProcessor* _root_processor; 4216 ParallelTaskTerminator _terminator; 4217 uint _n_workers; 4218 4219 public: 4220 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 4221 : AbstractGangTask("G1 collection"), 4222 _g1h(g1h), 4223 _pss(per_thread_states), 4224 _queues(task_queues), 4225 _root_processor(root_processor), 4226 _terminator(n_workers, _queues), 4227 _n_workers(n_workers) 4228 {} 4229 4230 void work(uint worker_id) { 4231 if (worker_id >= _n_workers) return; // no work needed this round 4232 4233 double start_sec = os::elapsedTime(); 4234 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 4235 4236 { 4237 ResourceMark rm; 4238 HandleMark hm; 4239 4240 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4241 4242 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4243 pss->set_ref_processor(rp); 4244 4245 double start_strong_roots_sec = os::elapsedTime(); 4246 4247 _root_processor->evacuate_roots(pss->closures(), worker_id); 4248 4249 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss); 4250 4251 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid 4252 // treating the nmethods visited to act as roots for concurrent marking. 4253 // We only want to make sure that the oops in the nmethods are adjusted with regard to the 4254 // objects copied by the current evacuation. 4255 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl, 4256 pss->closures()->weak_codeblobs(), 4257 worker_id); 4258 4259 _pss->add_cards_scanned(worker_id, cards_scanned); 4260 4261 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 4262 4263 double term_sec = 0.0; 4264 size_t evac_term_attempts = 0; 4265 { 4266 double start = os::elapsedTime(); 4267 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator); 4268 evac.do_void(); 4269 4270 evac_term_attempts = evac.term_attempts(); 4271 term_sec = evac.term_time(); 4272 double elapsed_sec = os::elapsedTime() - start; 4273 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 4274 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 4275 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 4276 } 4277 4278 assert(pss->queue_is_empty(), "should be empty"); 4279 4280 if (PrintTerminationStats) { 4281 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 4282 size_t lab_waste; 4283 size_t lab_undo_waste; 4284 pss->waste(lab_waste, lab_undo_waste); 4285 _g1h->print_termination_stats(gclog_or_tty, 4286 worker_id, 4287 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 4288 strong_roots_sec * 1000.0, /* strong roots time */ 4289 term_sec * 1000.0, /* evac term time */ 4290 evac_term_attempts, /* evac term attempts */ 4291 lab_waste, /* alloc buffer waste */ 4292 lab_undo_waste /* undo waste */ 4293 ); 4294 } 4295 4296 // Close the inner scope so that the ResourceMark and HandleMark 4297 // destructors are executed here and are included as part of the 4298 // "GC Worker Time". 4299 } 4300 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 4301 } 4302 }; 4303 4304 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) { 4305 st->print_raw_cr("GC Termination Stats"); 4306 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 4307 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo"); 4308 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 4309 } 4310 4311 void G1CollectedHeap::print_termination_stats(outputStream* const st, 4312 uint worker_id, 4313 double elapsed_ms, 4314 double strong_roots_ms, 4315 double term_ms, 4316 size_t term_attempts, 4317 size_t alloc_buffer_waste, 4318 size_t undo_waste) const { 4319 st->print_cr("%3d %9.2f %9.2f %6.2f " 4320 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 4321 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 4322 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 4323 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 4324 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 4325 alloc_buffer_waste * HeapWordSize / K, 4326 undo_waste * HeapWordSize / K); 4327 } 4328 4329 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4330 private: 4331 BoolObjectClosure* _is_alive; 4332 int _initial_string_table_size; 4333 int _initial_symbol_table_size; 4334 4335 bool _process_strings; 4336 int _strings_processed; 4337 int _strings_removed; 4338 4339 bool _process_symbols; 4340 int _symbols_processed; 4341 int _symbols_removed; 4342 4343 public: 4344 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4345 AbstractGangTask("String/Symbol Unlinking"), 4346 _is_alive(is_alive), 4347 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4348 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4349 4350 _initial_string_table_size = StringTable::the_table()->table_size(); 4351 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4352 if (process_strings) { 4353 StringTable::clear_parallel_claimed_index(); 4354 } 4355 if (process_symbols) { 4356 SymbolTable::clear_parallel_claimed_index(); 4357 } 4358 } 4359 4360 ~G1StringSymbolTableUnlinkTask() { 4361 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4362 "claim value %d after unlink less than initial string table size %d", 4363 StringTable::parallel_claimed_index(), _initial_string_table_size); 4364 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4365 "claim value %d after unlink less than initial symbol table size %d", 4366 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size); 4367 4368 if (G1TraceStringSymbolTableScrubbing) { 4369 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4370 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, " 4371 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed", 4372 strings_processed(), strings_removed(), 4373 symbols_processed(), symbols_removed()); 4374 } 4375 } 4376 4377 void work(uint worker_id) { 4378 int strings_processed = 0; 4379 int strings_removed = 0; 4380 int symbols_processed = 0; 4381 int symbols_removed = 0; 4382 if (_process_strings) { 4383 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4384 Atomic::add(strings_processed, &_strings_processed); 4385 Atomic::add(strings_removed, &_strings_removed); 4386 } 4387 if (_process_symbols) { 4388 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 4389 Atomic::add(symbols_processed, &_symbols_processed); 4390 Atomic::add(symbols_removed, &_symbols_removed); 4391 } 4392 } 4393 4394 size_t strings_processed() const { return (size_t)_strings_processed; } 4395 size_t strings_removed() const { return (size_t)_strings_removed; } 4396 4397 size_t symbols_processed() const { return (size_t)_symbols_processed; } 4398 size_t symbols_removed() const { return (size_t)_symbols_removed; } 4399 }; 4400 4401 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 4402 private: 4403 static Monitor* _lock; 4404 4405 BoolObjectClosure* const _is_alive; 4406 const bool _unloading_occurred; 4407 const uint _num_workers; 4408 4409 // Variables used to claim nmethods. 4410 nmethod* _first_nmethod; 4411 volatile nmethod* _claimed_nmethod; 4412 4413 // The list of nmethods that need to be processed by the second pass. 4414 volatile nmethod* _postponed_list; 4415 volatile uint _num_entered_barrier; 4416 4417 public: 4418 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 4419 _is_alive(is_alive), 4420 _unloading_occurred(unloading_occurred), 4421 _num_workers(num_workers), 4422 _first_nmethod(NULL), 4423 _claimed_nmethod(NULL), 4424 _postponed_list(NULL), 4425 _num_entered_barrier(0) 4426 { 4427 nmethod::increase_unloading_clock(); 4428 // Get first alive nmethod 4429 NMethodIterator iter = NMethodIterator(); 4430 if(iter.next_alive()) { 4431 _first_nmethod = iter.method(); 4432 } 4433 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 4434 } 4435 4436 ~G1CodeCacheUnloadingTask() { 4437 CodeCache::verify_clean_inline_caches(); 4438 4439 CodeCache::set_needs_cache_clean(false); 4440 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 4441 4442 CodeCache::verify_icholder_relocations(); 4443 } 4444 4445 private: 4446 void add_to_postponed_list(nmethod* nm) { 4447 nmethod* old; 4448 do { 4449 old = (nmethod*)_postponed_list; 4450 nm->set_unloading_next(old); 4451 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 4452 } 4453 4454 void clean_nmethod(nmethod* nm) { 4455 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 4456 4457 if (postponed) { 4458 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 4459 add_to_postponed_list(nm); 4460 } 4461 4462 // Mark that this thread has been cleaned/unloaded. 4463 // After this call, it will be safe to ask if this nmethod was unloaded or not. 4464 nm->set_unloading_clock(nmethod::global_unloading_clock()); 4465 } 4466 4467 void clean_nmethod_postponed(nmethod* nm) { 4468 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 4469 } 4470 4471 static const int MaxClaimNmethods = 16; 4472 4473 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 4474 nmethod* first; 4475 NMethodIterator last; 4476 4477 do { 4478 *num_claimed_nmethods = 0; 4479 4480 first = (nmethod*)_claimed_nmethod; 4481 last = NMethodIterator(first); 4482 4483 if (first != NULL) { 4484 4485 for (int i = 0; i < MaxClaimNmethods; i++) { 4486 if (!last.next_alive()) { 4487 break; 4488 } 4489 claimed_nmethods[i] = last.method(); 4490 (*num_claimed_nmethods)++; 4491 } 4492 } 4493 4494 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 4495 } 4496 4497 nmethod* claim_postponed_nmethod() { 4498 nmethod* claim; 4499 nmethod* next; 4500 4501 do { 4502 claim = (nmethod*)_postponed_list; 4503 if (claim == NULL) { 4504 return NULL; 4505 } 4506 4507 next = claim->unloading_next(); 4508 4509 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 4510 4511 return claim; 4512 } 4513 4514 public: 4515 // Mark that we're done with the first pass of nmethod cleaning. 4516 void barrier_mark(uint worker_id) { 4517 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4518 _num_entered_barrier++; 4519 if (_num_entered_barrier == _num_workers) { 4520 ml.notify_all(); 4521 } 4522 } 4523 4524 // See if we have to wait for the other workers to 4525 // finish their first-pass nmethod cleaning work. 4526 void barrier_wait(uint worker_id) { 4527 if (_num_entered_barrier < _num_workers) { 4528 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4529 while (_num_entered_barrier < _num_workers) { 4530 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 4531 } 4532 } 4533 } 4534 4535 // Cleaning and unloading of nmethods. Some work has to be postponed 4536 // to the second pass, when we know which nmethods survive. 4537 void work_first_pass(uint worker_id) { 4538 // The first nmethods is claimed by the first worker. 4539 if (worker_id == 0 && _first_nmethod != NULL) { 4540 clean_nmethod(_first_nmethod); 4541 _first_nmethod = NULL; 4542 } 4543 4544 int num_claimed_nmethods; 4545 nmethod* claimed_nmethods[MaxClaimNmethods]; 4546 4547 while (true) { 4548 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 4549 4550 if (num_claimed_nmethods == 0) { 4551 break; 4552 } 4553 4554 for (int i = 0; i < num_claimed_nmethods; i++) { 4555 clean_nmethod(claimed_nmethods[i]); 4556 } 4557 } 4558 } 4559 4560 void work_second_pass(uint worker_id) { 4561 nmethod* nm; 4562 // Take care of postponed nmethods. 4563 while ((nm = claim_postponed_nmethod()) != NULL) { 4564 clean_nmethod_postponed(nm); 4565 } 4566 } 4567 }; 4568 4569 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 4570 4571 class G1KlassCleaningTask : public StackObj { 4572 BoolObjectClosure* _is_alive; 4573 volatile jint _clean_klass_tree_claimed; 4574 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 4575 4576 public: 4577 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 4578 _is_alive(is_alive), 4579 _clean_klass_tree_claimed(0), 4580 _klass_iterator() { 4581 } 4582 4583 private: 4584 bool claim_clean_klass_tree_task() { 4585 if (_clean_klass_tree_claimed) { 4586 return false; 4587 } 4588 4589 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 4590 } 4591 4592 InstanceKlass* claim_next_klass() { 4593 Klass* klass; 4594 do { 4595 klass =_klass_iterator.next_klass(); 4596 } while (klass != NULL && !klass->is_instance_klass()); 4597 4598 // this can be null so don't call InstanceKlass::cast 4599 return static_cast<InstanceKlass*>(klass); 4600 } 4601 4602 public: 4603 4604 void clean_klass(InstanceKlass* ik) { 4605 ik->clean_weak_instanceklass_links(_is_alive); 4606 } 4607 4608 void work() { 4609 ResourceMark rm; 4610 4611 // One worker will clean the subklass/sibling klass tree. 4612 if (claim_clean_klass_tree_task()) { 4613 Klass::clean_subklass_tree(_is_alive); 4614 } 4615 4616 // All workers will help cleaning the classes, 4617 InstanceKlass* klass; 4618 while ((klass = claim_next_klass()) != NULL) { 4619 clean_klass(klass); 4620 } 4621 } 4622 }; 4623 4624 // To minimize the remark pause times, the tasks below are done in parallel. 4625 class G1ParallelCleaningTask : public AbstractGangTask { 4626 private: 4627 G1StringSymbolTableUnlinkTask _string_symbol_task; 4628 G1CodeCacheUnloadingTask _code_cache_task; 4629 G1KlassCleaningTask _klass_cleaning_task; 4630 4631 public: 4632 // The constructor is run in the VMThread. 4633 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 4634 AbstractGangTask("Parallel Cleaning"), 4635 _string_symbol_task(is_alive, process_strings, process_symbols), 4636 _code_cache_task(num_workers, is_alive, unloading_occurred), 4637 _klass_cleaning_task(is_alive) { 4638 } 4639 4640 // The parallel work done by all worker threads. 4641 void work(uint worker_id) { 4642 // Do first pass of code cache cleaning. 4643 _code_cache_task.work_first_pass(worker_id); 4644 4645 // Let the threads mark that the first pass is done. 4646 _code_cache_task.barrier_mark(worker_id); 4647 4648 // Clean the Strings and Symbols. 4649 _string_symbol_task.work(worker_id); 4650 4651 // Wait for all workers to finish the first code cache cleaning pass. 4652 _code_cache_task.barrier_wait(worker_id); 4653 4654 // Do the second code cache cleaning work, which realize on 4655 // the liveness information gathered during the first pass. 4656 _code_cache_task.work_second_pass(worker_id); 4657 4658 // Clean all klasses that were not unloaded. 4659 _klass_cleaning_task.work(); 4660 } 4661 }; 4662 4663 4664 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 4665 bool process_strings, 4666 bool process_symbols, 4667 bool class_unloading_occurred) { 4668 uint n_workers = workers()->active_workers(); 4669 4670 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 4671 n_workers, class_unloading_occurred); 4672 workers()->run_task(&g1_unlink_task); 4673 } 4674 4675 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 4676 bool process_strings, bool process_symbols) { 4677 { 4678 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 4679 workers()->run_task(&g1_unlink_task); 4680 } 4681 4682 if (G1StringDedup::is_enabled()) { 4683 G1StringDedup::unlink(is_alive); 4684 } 4685 } 4686 4687 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 4688 private: 4689 DirtyCardQueueSet* _queue; 4690 public: 4691 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 4692 4693 virtual void work(uint worker_id) { 4694 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4695 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 4696 4697 RedirtyLoggedCardTableEntryClosure cl; 4698 _queue->par_apply_closure_to_all_completed_buffers(&cl); 4699 4700 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed()); 4701 } 4702 }; 4703 4704 void G1CollectedHeap::redirty_logged_cards() { 4705 double redirty_logged_cards_start = os::elapsedTime(); 4706 4707 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 4708 dirty_card_queue_set().reset_for_par_iteration(); 4709 workers()->run_task(&redirty_task); 4710 4711 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 4712 dcq.merge_bufferlists(&dirty_card_queue_set()); 4713 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 4714 4715 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 4716 } 4717 4718 // Weak Reference Processing support 4719 4720 // An always "is_alive" closure that is used to preserve referents. 4721 // If the object is non-null then it's alive. Used in the preservation 4722 // of referent objects that are pointed to by reference objects 4723 // discovered by the CM ref processor. 4724 class G1AlwaysAliveClosure: public BoolObjectClosure { 4725 G1CollectedHeap* _g1; 4726 public: 4727 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4728 bool do_object_b(oop p) { 4729 if (p != NULL) { 4730 return true; 4731 } 4732 return false; 4733 } 4734 }; 4735 4736 bool G1STWIsAliveClosure::do_object_b(oop p) { 4737 // An object is reachable if it is outside the collection set, 4738 // or is inside and copied. 4739 return !_g1->is_in_cset(p) || p->is_forwarded(); 4740 } 4741 4742 // Non Copying Keep Alive closure 4743 class G1KeepAliveClosure: public OopClosure { 4744 G1CollectedHeap* _g1; 4745 public: 4746 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4747 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 4748 void do_oop(oop* p) { 4749 oop obj = *p; 4750 assert(obj != NULL, "the caller should have filtered out NULL values"); 4751 4752 const InCSetState cset_state = _g1->in_cset_state(obj); 4753 if (!cset_state.is_in_cset_or_humongous()) { 4754 return; 4755 } 4756 if (cset_state.is_in_cset()) { 4757 assert( obj->is_forwarded(), "invariant" ); 4758 *p = obj->forwardee(); 4759 } else { 4760 assert(!obj->is_forwarded(), "invariant" ); 4761 assert(cset_state.is_humongous(), 4762 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 4763 _g1->set_humongous_is_live(obj); 4764 } 4765 } 4766 }; 4767 4768 // Copying Keep Alive closure - can be called from both 4769 // serial and parallel code as long as different worker 4770 // threads utilize different G1ParScanThreadState instances 4771 // and different queues. 4772 4773 class G1CopyingKeepAliveClosure: public OopClosure { 4774 G1CollectedHeap* _g1h; 4775 OopClosure* _copy_non_heap_obj_cl; 4776 G1ParScanThreadState* _par_scan_state; 4777 4778 public: 4779 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 4780 OopClosure* non_heap_obj_cl, 4781 G1ParScanThreadState* pss): 4782 _g1h(g1h), 4783 _copy_non_heap_obj_cl(non_heap_obj_cl), 4784 _par_scan_state(pss) 4785 {} 4786 4787 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 4788 virtual void do_oop( oop* p) { do_oop_work(p); } 4789 4790 template <class T> void do_oop_work(T* p) { 4791 oop obj = oopDesc::load_decode_heap_oop(p); 4792 4793 if (_g1h->is_in_cset_or_humongous(obj)) { 4794 // If the referent object has been forwarded (either copied 4795 // to a new location or to itself in the event of an 4796 // evacuation failure) then we need to update the reference 4797 // field and, if both reference and referent are in the G1 4798 // heap, update the RSet for the referent. 4799 // 4800 // If the referent has not been forwarded then we have to keep 4801 // it alive by policy. Therefore we have copy the referent. 4802 // 4803 // If the reference field is in the G1 heap then we can push 4804 // on the PSS queue. When the queue is drained (after each 4805 // phase of reference processing) the object and it's followers 4806 // will be copied, the reference field set to point to the 4807 // new location, and the RSet updated. Otherwise we need to 4808 // use the the non-heap or metadata closures directly to copy 4809 // the referent object and update the pointer, while avoiding 4810 // updating the RSet. 4811 4812 if (_g1h->is_in_g1_reserved(p)) { 4813 _par_scan_state->push_on_queue(p); 4814 } else { 4815 assert(!Metaspace::contains((const void*)p), 4816 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)); 4817 _copy_non_heap_obj_cl->do_oop(p); 4818 } 4819 } 4820 } 4821 }; 4822 4823 // Serial drain queue closure. Called as the 'complete_gc' 4824 // closure for each discovered list in some of the 4825 // reference processing phases. 4826 4827 class G1STWDrainQueueClosure: public VoidClosure { 4828 protected: 4829 G1CollectedHeap* _g1h; 4830 G1ParScanThreadState* _par_scan_state; 4831 4832 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4833 4834 public: 4835 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 4836 _g1h(g1h), 4837 _par_scan_state(pss) 4838 { } 4839 4840 void do_void() { 4841 G1ParScanThreadState* const pss = par_scan_state(); 4842 pss->trim_queue(); 4843 } 4844 }; 4845 4846 // Parallel Reference Processing closures 4847 4848 // Implementation of AbstractRefProcTaskExecutor for parallel reference 4849 // processing during G1 evacuation pauses. 4850 4851 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 4852 private: 4853 G1CollectedHeap* _g1h; 4854 G1ParScanThreadStateSet* _pss; 4855 RefToScanQueueSet* _queues; 4856 WorkGang* _workers; 4857 uint _active_workers; 4858 4859 public: 4860 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 4861 G1ParScanThreadStateSet* per_thread_states, 4862 WorkGang* workers, 4863 RefToScanQueueSet *task_queues, 4864 uint n_workers) : 4865 _g1h(g1h), 4866 _pss(per_thread_states), 4867 _queues(task_queues), 4868 _workers(workers), 4869 _active_workers(n_workers) 4870 { 4871 assert(n_workers > 0, "shouldn't call this otherwise"); 4872 } 4873 4874 // Executes the given task using concurrent marking worker threads. 4875 virtual void execute(ProcessTask& task); 4876 virtual void execute(EnqueueTask& task); 4877 }; 4878 4879 // Gang task for possibly parallel reference processing 4880 4881 class G1STWRefProcTaskProxy: public AbstractGangTask { 4882 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 4883 ProcessTask& _proc_task; 4884 G1CollectedHeap* _g1h; 4885 G1ParScanThreadStateSet* _pss; 4886 RefToScanQueueSet* _task_queues; 4887 ParallelTaskTerminator* _terminator; 4888 4889 public: 4890 G1STWRefProcTaskProxy(ProcessTask& proc_task, 4891 G1CollectedHeap* g1h, 4892 G1ParScanThreadStateSet* per_thread_states, 4893 RefToScanQueueSet *task_queues, 4894 ParallelTaskTerminator* terminator) : 4895 AbstractGangTask("Process reference objects in parallel"), 4896 _proc_task(proc_task), 4897 _g1h(g1h), 4898 _pss(per_thread_states), 4899 _task_queues(task_queues), 4900 _terminator(terminator) 4901 {} 4902 4903 virtual void work(uint worker_id) { 4904 // The reference processing task executed by a single worker. 4905 ResourceMark rm; 4906 HandleMark hm; 4907 4908 G1STWIsAliveClosure is_alive(_g1h); 4909 4910 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4911 pss->set_ref_processor(NULL); 4912 4913 // Keep alive closure. 4914 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 4915 4916 // Complete GC closure 4917 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator); 4918 4919 // Call the reference processing task's work routine. 4920 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 4921 4922 // Note we cannot assert that the refs array is empty here as not all 4923 // of the processing tasks (specifically phase2 - pp2_work) execute 4924 // the complete_gc closure (which ordinarily would drain the queue) so 4925 // the queue may not be empty. 4926 } 4927 }; 4928 4929 // Driver routine for parallel reference processing. 4930 // Creates an instance of the ref processing gang 4931 // task and has the worker threads execute it. 4932 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 4933 assert(_workers != NULL, "Need parallel worker threads."); 4934 4935 ParallelTaskTerminator terminator(_active_workers, _queues); 4936 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 4937 4938 _workers->run_task(&proc_task_proxy); 4939 } 4940 4941 // Gang task for parallel reference enqueueing. 4942 4943 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 4944 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 4945 EnqueueTask& _enq_task; 4946 4947 public: 4948 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 4949 AbstractGangTask("Enqueue reference objects in parallel"), 4950 _enq_task(enq_task) 4951 { } 4952 4953 virtual void work(uint worker_id) { 4954 _enq_task.work(worker_id); 4955 } 4956 }; 4957 4958 // Driver routine for parallel reference enqueueing. 4959 // Creates an instance of the ref enqueueing gang 4960 // task and has the worker threads execute it. 4961 4962 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 4963 assert(_workers != NULL, "Need parallel worker threads."); 4964 4965 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 4966 4967 _workers->run_task(&enq_task_proxy); 4968 } 4969 4970 // End of weak reference support closures 4971 4972 // Abstract task used to preserve (i.e. copy) any referent objects 4973 // that are in the collection set and are pointed to by reference 4974 // objects discovered by the CM ref processor. 4975 4976 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 4977 protected: 4978 G1CollectedHeap* _g1h; 4979 G1ParScanThreadStateSet* _pss; 4980 RefToScanQueueSet* _queues; 4981 ParallelTaskTerminator _terminator; 4982 uint _n_workers; 4983 4984 public: 4985 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) : 4986 AbstractGangTask("ParPreserveCMReferents"), 4987 _g1h(g1h), 4988 _pss(per_thread_states), 4989 _queues(task_queues), 4990 _terminator(workers, _queues), 4991 _n_workers(workers) 4992 { } 4993 4994 void work(uint worker_id) { 4995 ResourceMark rm; 4996 HandleMark hm; 4997 4998 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4999 pss->set_ref_processor(NULL); 5000 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 5001 5002 // Is alive closure 5003 G1AlwaysAliveClosure always_alive(_g1h); 5004 5005 // Copying keep alive closure. Applied to referent objects that need 5006 // to be copied. 5007 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 5008 5009 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5010 5011 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5012 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5013 5014 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5015 // So this must be true - but assert just in case someone decides to 5016 // change the worker ids. 5017 assert(worker_id < limit, "sanity"); 5018 assert(!rp->discovery_is_atomic(), "check this code"); 5019 5020 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5021 for (uint idx = worker_id; idx < limit; idx += stride) { 5022 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5023 5024 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5025 while (iter.has_next()) { 5026 // Since discovery is not atomic for the CM ref processor, we 5027 // can see some null referent objects. 5028 iter.load_ptrs(DEBUG_ONLY(true)); 5029 oop ref = iter.obj(); 5030 5031 // This will filter nulls. 5032 if (iter.is_referent_alive()) { 5033 iter.make_referent_alive(); 5034 } 5035 iter.move_to_next(); 5036 } 5037 } 5038 5039 // Drain the queue - which may cause stealing 5040 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator); 5041 drain_queue.do_void(); 5042 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5043 assert(pss->queue_is_empty(), "should be"); 5044 } 5045 }; 5046 5047 // Weak Reference processing during an evacuation pause (part 1). 5048 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 5049 double ref_proc_start = os::elapsedTime(); 5050 5051 ReferenceProcessor* rp = _ref_processor_stw; 5052 assert(rp->discovery_enabled(), "should have been enabled"); 5053 5054 // Any reference objects, in the collection set, that were 'discovered' 5055 // by the CM ref processor should have already been copied (either by 5056 // applying the external root copy closure to the discovered lists, or 5057 // by following an RSet entry). 5058 // 5059 // But some of the referents, that are in the collection set, that these 5060 // reference objects point to may not have been copied: the STW ref 5061 // processor would have seen that the reference object had already 5062 // been 'discovered' and would have skipped discovering the reference, 5063 // but would not have treated the reference object as a regular oop. 5064 // As a result the copy closure would not have been applied to the 5065 // referent object. 5066 // 5067 // We need to explicitly copy these referent objects - the references 5068 // will be processed at the end of remarking. 5069 // 5070 // We also need to do this copying before we process the reference 5071 // objects discovered by the STW ref processor in case one of these 5072 // referents points to another object which is also referenced by an 5073 // object discovered by the STW ref processor. 5074 5075 uint no_of_gc_workers = workers()->active_workers(); 5076 5077 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5078 per_thread_states, 5079 no_of_gc_workers, 5080 _task_queues); 5081 5082 workers()->run_task(&keep_cm_referents); 5083 5084 // Closure to test whether a referent is alive. 5085 G1STWIsAliveClosure is_alive(this); 5086 5087 // Even when parallel reference processing is enabled, the processing 5088 // of JNI refs is serial and performed serially by the current thread 5089 // rather than by a worker. The following PSS will be used for processing 5090 // JNI refs. 5091 5092 // Use only a single queue for this PSS. 5093 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 5094 pss->set_ref_processor(NULL); 5095 assert(pss->queue_is_empty(), "pre-condition"); 5096 5097 // Keep alive closure. 5098 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss); 5099 5100 // Serial Complete GC closure 5101 G1STWDrainQueueClosure drain_queue(this, pss); 5102 5103 // Setup the soft refs policy... 5104 rp->setup_policy(false); 5105 5106 ReferenceProcessorStats stats; 5107 if (!rp->processing_is_mt()) { 5108 // Serial reference processing... 5109 stats = rp->process_discovered_references(&is_alive, 5110 &keep_alive, 5111 &drain_queue, 5112 NULL, 5113 _gc_timer_stw); 5114 } else { 5115 // Parallel reference processing 5116 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5117 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5118 5119 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers); 5120 stats = rp->process_discovered_references(&is_alive, 5121 &keep_alive, 5122 &drain_queue, 5123 &par_task_executor, 5124 _gc_timer_stw); 5125 } 5126 5127 _gc_tracer_stw->report_gc_reference_stats(stats); 5128 5129 // We have completed copying any necessary live referent objects. 5130 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 5131 5132 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5133 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5134 } 5135 5136 // Weak Reference processing during an evacuation pause (part 2). 5137 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 5138 double ref_enq_start = os::elapsedTime(); 5139 5140 ReferenceProcessor* rp = _ref_processor_stw; 5141 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5142 5143 // Now enqueue any remaining on the discovered lists on to 5144 // the pending list. 5145 if (!rp->processing_is_mt()) { 5146 // Serial reference processing... 5147 rp->enqueue_discovered_references(); 5148 } else { 5149 // Parallel reference enqueueing 5150 5151 uint n_workers = workers()->active_workers(); 5152 5153 assert(rp->num_q() == n_workers, "sanity"); 5154 assert(n_workers <= rp->max_num_q(), "sanity"); 5155 5156 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers); 5157 rp->enqueue_discovered_references(&par_task_executor); 5158 } 5159 5160 rp->verify_no_references_recorded(); 5161 assert(!rp->discovery_enabled(), "should have been disabled"); 5162 5163 // FIXME 5164 // CM's reference processing also cleans up the string and symbol tables. 5165 // Should we do that here also? We could, but it is a serial operation 5166 // and could significantly increase the pause time. 5167 5168 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5169 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5170 } 5171 5172 void G1CollectedHeap::pre_evacuate_collection_set() { 5173 _expand_heap_after_alloc_failure = true; 5174 _evacuation_failed = false; 5175 5176 // Disable the hot card cache. 5177 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5178 hot_card_cache->reset_hot_cache_claimed_index(); 5179 hot_card_cache->set_use_cache(false); 5180 5181 } 5182 5183 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 5184 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5185 5186 // Should G1EvacuationFailureALot be in effect for this GC? 5187 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5188 5189 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5190 double start_par_time_sec = os::elapsedTime(); 5191 double end_par_time_sec; 5192 5193 { 5194 const uint n_workers = workers()->active_workers(); 5195 G1RootProcessor root_processor(this, n_workers); 5196 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 5197 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5198 if (collector_state()->during_initial_mark_pause()) { 5199 ClassLoaderDataGraph::clear_claimed_marks(); 5200 } 5201 5202 // The individual threads will set their evac-failure closures. 5203 if (PrintTerminationStats) { 5204 print_termination_stats_hdr(gclog_or_tty); 5205 } 5206 5207 workers()->run_task(&g1_par_task); 5208 end_par_time_sec = os::elapsedTime(); 5209 5210 // Closing the inner scope will execute the destructor 5211 // for the G1RootProcessor object. We record the current 5212 // elapsed time before closing the scope so that time 5213 // taken for the destructor is NOT included in the 5214 // reported parallel time. 5215 } 5216 5217 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 5218 5219 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5220 phase_times->record_par_time(par_time_ms); 5221 5222 double code_root_fixup_time_ms = 5223 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5224 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 5225 5226 // Process any discovered reference objects - we have 5227 // to do this _before_ we retire the GC alloc regions 5228 // as we may have to copy some 'reachable' referent 5229 // objects (and their reachable sub-graphs) that were 5230 // not copied during the pause. 5231 process_discovered_references(per_thread_states); 5232 5233 if (G1StringDedup::is_enabled()) { 5234 double fixup_start = os::elapsedTime(); 5235 5236 G1STWIsAliveClosure is_alive(this); 5237 G1KeepAliveClosure keep_alive(this); 5238 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times); 5239 5240 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 5241 phase_times->record_string_dedup_fixup_time(fixup_time_ms); 5242 } 5243 5244 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5245 5246 if (evacuation_failed()) { 5247 remove_self_forwarding_pointers(); 5248 5249 // Reset the G1EvacuationFailureALot counters and flags 5250 // Note: the values are reset only when an actual 5251 // evacuation failure occurs. 5252 NOT_PRODUCT(reset_evacuation_should_fail();) 5253 } 5254 5255 // Enqueue any remaining references remaining on the STW 5256 // reference processor's discovered lists. We need to do 5257 // this after the card table is cleaned (and verified) as 5258 // the act of enqueueing entries on to the pending list 5259 // will log these updates (and dirty their associated 5260 // cards). We need these updates logged to update any 5261 // RSets. 5262 enqueue_discovered_references(per_thread_states); 5263 } 5264 5265 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 5266 _allocator->release_gc_alloc_regions(evacuation_info); 5267 5268 per_thread_states->flush(); 5269 5270 record_obj_copy_mem_stats(); 5271 5272 // Reset and re-enable the hot card cache. 5273 // Note the counts for the cards in the regions in the 5274 // collection set are reset when the collection set is freed. 5275 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5276 hot_card_cache->reset_hot_cache(); 5277 hot_card_cache->set_use_cache(true); 5278 5279 purge_code_root_memory(); 5280 5281 redirty_logged_cards(); 5282 #if defined(COMPILER2) || INCLUDE_JVMCI 5283 DerivedPointerTable::update_pointers(); 5284 #endif 5285 } 5286 5287 void G1CollectedHeap::record_obj_copy_mem_stats() { 5288 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 5289 create_g1_evac_summary(&_old_evac_stats)); 5290 } 5291 5292 void G1CollectedHeap::free_region(HeapRegion* hr, 5293 FreeRegionList* free_list, 5294 bool par, 5295 bool locked) { 5296 assert(!hr->is_free(), "the region should not be free"); 5297 assert(!hr->is_empty(), "the region should not be empty"); 5298 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 5299 assert(free_list != NULL, "pre-condition"); 5300 5301 if (G1VerifyBitmaps) { 5302 MemRegion mr(hr->bottom(), hr->end()); 5303 concurrent_mark()->clearRangePrevBitmap(mr); 5304 } 5305 5306 // Clear the card counts for this region. 5307 // Note: we only need to do this if the region is not young 5308 // (since we don't refine cards in young regions). 5309 if (!hr->is_young()) { 5310 _cg1r->hot_card_cache()->reset_card_counts(hr); 5311 } 5312 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5313 free_list->add_ordered(hr); 5314 } 5315 5316 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5317 FreeRegionList* free_list, 5318 bool par) { 5319 assert(hr->is_starts_humongous(), "this is only for starts humongous regions"); 5320 assert(free_list != NULL, "pre-condition"); 5321 5322 size_t hr_capacity = hr->capacity(); 5323 // We need to read this before we make the region non-humongous, 5324 // otherwise the information will be gone. 5325 uint last_index = hr->last_hc_index(); 5326 hr->clear_humongous(); 5327 free_region(hr, free_list, par); 5328 5329 uint i = hr->hrm_index() + 1; 5330 while (i < last_index) { 5331 HeapRegion* curr_hr = region_at(i); 5332 assert(curr_hr->is_continues_humongous(), "invariant"); 5333 curr_hr->clear_humongous(); 5334 free_region(curr_hr, free_list, par); 5335 i += 1; 5336 } 5337 } 5338 5339 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 5340 const HeapRegionSetCount& humongous_regions_removed) { 5341 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5342 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5343 _old_set.bulk_remove(old_regions_removed); 5344 _humongous_set.bulk_remove(humongous_regions_removed); 5345 } 5346 5347 } 5348 5349 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 5350 assert(list != NULL, "list can't be null"); 5351 if (!list->is_empty()) { 5352 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5353 _hrm.insert_list_into_free_list(list); 5354 } 5355 } 5356 5357 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 5358 decrease_used(bytes); 5359 } 5360 5361 class G1ParCleanupCTTask : public AbstractGangTask { 5362 G1SATBCardTableModRefBS* _ct_bs; 5363 G1CollectedHeap* _g1h; 5364 HeapRegion* volatile _su_head; 5365 public: 5366 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 5367 G1CollectedHeap* g1h) : 5368 AbstractGangTask("G1 Par Cleanup CT Task"), 5369 _ct_bs(ct_bs), _g1h(g1h) { } 5370 5371 void work(uint worker_id) { 5372 HeapRegion* r; 5373 while (r = _g1h->pop_dirty_cards_region()) { 5374 clear_cards(r); 5375 } 5376 } 5377 5378 void clear_cards(HeapRegion* r) { 5379 // Cards of the survivors should have already been dirtied. 5380 if (!r->is_survivor()) { 5381 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5382 } 5383 } 5384 }; 5385 5386 #ifndef PRODUCT 5387 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5388 G1CollectedHeap* _g1h; 5389 G1SATBCardTableModRefBS* _ct_bs; 5390 public: 5391 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 5392 : _g1h(g1h), _ct_bs(ct_bs) { } 5393 virtual bool doHeapRegion(HeapRegion* r) { 5394 if (r->is_survivor()) { 5395 _g1h->verify_dirty_region(r); 5396 } else { 5397 _g1h->verify_not_dirty_region(r); 5398 } 5399 return false; 5400 } 5401 }; 5402 5403 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5404 // All of the region should be clean. 5405 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5406 MemRegion mr(hr->bottom(), hr->end()); 5407 ct_bs->verify_not_dirty_region(mr); 5408 } 5409 5410 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5411 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5412 // dirty allocated blocks as they allocate them. The thread that 5413 // retires each region and replaces it with a new one will do a 5414 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5415 // not dirty that area (one less thing to have to do while holding 5416 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5417 // is dirty. 5418 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5419 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5420 if (hr->is_young()) { 5421 ct_bs->verify_g1_young_region(mr); 5422 } else { 5423 ct_bs->verify_dirty_region(mr); 5424 } 5425 } 5426 5427 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5428 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5429 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5430 verify_dirty_region(hr); 5431 } 5432 } 5433 5434 void G1CollectedHeap::verify_dirty_young_regions() { 5435 verify_dirty_young_list(_young_list->first_region()); 5436 } 5437 5438 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 5439 HeapWord* tams, HeapWord* end) { 5440 guarantee(tams <= end, 5441 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end)); 5442 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 5443 if (result < end) { 5444 gclog_or_tty->cr(); 5445 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT, 5446 bitmap_name, p2i(result)); 5447 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT, 5448 bitmap_name, p2i(tams), p2i(end)); 5449 return false; 5450 } 5451 return true; 5452 } 5453 5454 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 5455 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 5456 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 5457 5458 HeapWord* bottom = hr->bottom(); 5459 HeapWord* ptams = hr->prev_top_at_mark_start(); 5460 HeapWord* ntams = hr->next_top_at_mark_start(); 5461 HeapWord* end = hr->end(); 5462 5463 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 5464 5465 bool res_n = true; 5466 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 5467 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 5468 // if we happen to be in that state. 5469 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) { 5470 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 5471 } 5472 if (!res_p || !res_n) { 5473 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT, 5474 HR_FORMAT_PARAMS(hr)); 5475 gclog_or_tty->print_cr("#### Caller: %s", caller); 5476 return false; 5477 } 5478 return true; 5479 } 5480 5481 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 5482 if (!G1VerifyBitmaps) return; 5483 5484 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 5485 } 5486 5487 class G1VerifyBitmapClosure : public HeapRegionClosure { 5488 private: 5489 const char* _caller; 5490 G1CollectedHeap* _g1h; 5491 bool _failures; 5492 5493 public: 5494 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 5495 _caller(caller), _g1h(g1h), _failures(false) { } 5496 5497 bool failures() { return _failures; } 5498 5499 virtual bool doHeapRegion(HeapRegion* hr) { 5500 if (hr->is_continues_humongous()) return false; 5501 5502 bool result = _g1h->verify_bitmaps(_caller, hr); 5503 if (!result) { 5504 _failures = true; 5505 } 5506 return false; 5507 } 5508 }; 5509 5510 void G1CollectedHeap::check_bitmaps(const char* caller) { 5511 if (!G1VerifyBitmaps) return; 5512 5513 G1VerifyBitmapClosure cl(caller, this); 5514 heap_region_iterate(&cl); 5515 guarantee(!cl.failures(), "bitmap verification"); 5516 } 5517 5518 class G1CheckCSetFastTableClosure : public HeapRegionClosure { 5519 private: 5520 bool _failures; 5521 public: 5522 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { } 5523 5524 virtual bool doHeapRegion(HeapRegion* hr) { 5525 uint i = hr->hrm_index(); 5526 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i); 5527 if (hr->is_humongous()) { 5528 if (hr->in_collection_set()) { 5529 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i); 5530 _failures = true; 5531 return true; 5532 } 5533 if (cset_state.is_in_cset()) { 5534 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i); 5535 _failures = true; 5536 return true; 5537 } 5538 if (hr->is_continues_humongous() && cset_state.is_humongous()) { 5539 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i); 5540 _failures = true; 5541 return true; 5542 } 5543 } else { 5544 if (cset_state.is_humongous()) { 5545 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i); 5546 _failures = true; 5547 return true; 5548 } 5549 if (hr->in_collection_set() != cset_state.is_in_cset()) { 5550 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u", 5551 hr->in_collection_set(), cset_state.value(), i); 5552 _failures = true; 5553 return true; 5554 } 5555 if (cset_state.is_in_cset()) { 5556 if (hr->is_young() != (cset_state.is_young())) { 5557 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u", 5558 hr->is_young(), cset_state.value(), i); 5559 _failures = true; 5560 return true; 5561 } 5562 if (hr->is_old() != (cset_state.is_old())) { 5563 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u", 5564 hr->is_old(), cset_state.value(), i); 5565 _failures = true; 5566 return true; 5567 } 5568 } 5569 } 5570 return false; 5571 } 5572 5573 bool failures() const { return _failures; } 5574 }; 5575 5576 bool G1CollectedHeap::check_cset_fast_test() { 5577 G1CheckCSetFastTableClosure cl; 5578 _hrm.iterate(&cl); 5579 return !cl.failures(); 5580 } 5581 #endif // PRODUCT 5582 5583 void G1CollectedHeap::cleanUpCardTable() { 5584 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5585 double start = os::elapsedTime(); 5586 5587 { 5588 // Iterate over the dirty cards region list. 5589 G1ParCleanupCTTask cleanup_task(ct_bs, this); 5590 5591 workers()->run_task(&cleanup_task); 5592 #ifndef PRODUCT 5593 if (G1VerifyCTCleanup || VerifyAfterGC) { 5594 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 5595 heap_region_iterate(&cleanup_verifier); 5596 } 5597 #endif 5598 } 5599 5600 double elapsed = os::elapsedTime() - start; 5601 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 5602 } 5603 5604 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 5605 size_t pre_used = 0; 5606 FreeRegionList local_free_list("Local List for CSet Freeing"); 5607 5608 double young_time_ms = 0.0; 5609 double non_young_time_ms = 0.0; 5610 5611 // Since the collection set is a superset of the the young list, 5612 // all we need to do to clear the young list is clear its 5613 // head and length, and unlink any young regions in the code below 5614 _young_list->clear(); 5615 5616 G1CollectorPolicy* policy = g1_policy(); 5617 5618 double start_sec = os::elapsedTime(); 5619 bool non_young = true; 5620 5621 HeapRegion* cur = cs_head; 5622 int age_bound = -1; 5623 size_t rs_lengths = 0; 5624 5625 while (cur != NULL) { 5626 assert(!is_on_master_free_list(cur), "sanity"); 5627 if (non_young) { 5628 if (cur->is_young()) { 5629 double end_sec = os::elapsedTime(); 5630 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5631 non_young_time_ms += elapsed_ms; 5632 5633 start_sec = os::elapsedTime(); 5634 non_young = false; 5635 } 5636 } else { 5637 if (!cur->is_young()) { 5638 double end_sec = os::elapsedTime(); 5639 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5640 young_time_ms += elapsed_ms; 5641 5642 start_sec = os::elapsedTime(); 5643 non_young = true; 5644 } 5645 } 5646 5647 rs_lengths += cur->rem_set()->occupied_locked(); 5648 5649 HeapRegion* next = cur->next_in_collection_set(); 5650 assert(cur->in_collection_set(), "bad CS"); 5651 cur->set_next_in_collection_set(NULL); 5652 clear_in_cset(cur); 5653 5654 if (cur->is_young()) { 5655 int index = cur->young_index_in_cset(); 5656 assert(index != -1, "invariant"); 5657 assert((uint) index < policy->young_cset_region_length(), "invariant"); 5658 size_t words_survived = surviving_young_words[index]; 5659 cur->record_surv_words_in_group(words_survived); 5660 5661 // At this point the we have 'popped' cur from the collection set 5662 // (linked via next_in_collection_set()) but it is still in the 5663 // young list (linked via next_young_region()). Clear the 5664 // _next_young_region field. 5665 cur->set_next_young_region(NULL); 5666 } else { 5667 int index = cur->young_index_in_cset(); 5668 assert(index == -1, "invariant"); 5669 } 5670 5671 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 5672 (!cur->is_young() && cur->young_index_in_cset() == -1), 5673 "invariant" ); 5674 5675 if (!cur->evacuation_failed()) { 5676 MemRegion used_mr = cur->used_region(); 5677 5678 // And the region is empty. 5679 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 5680 pre_used += cur->used(); 5681 free_region(cur, &local_free_list, false /* par */, true /* locked */); 5682 } else { 5683 cur->uninstall_surv_rate_group(); 5684 if (cur->is_young()) { 5685 cur->set_young_index_in_cset(-1); 5686 } 5687 cur->set_evacuation_failed(false); 5688 // The region is now considered to be old. 5689 cur->set_old(); 5690 // Do some allocation statistics accounting. Regions that failed evacuation 5691 // are always made old, so there is no need to update anything in the young 5692 // gen statistics, but we need to update old gen statistics. 5693 size_t used_words = cur->marked_bytes() / HeapWordSize; 5694 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words); 5695 _old_set.add(cur); 5696 evacuation_info.increment_collectionset_used_after(cur->used()); 5697 } 5698 cur = next; 5699 } 5700 5701 evacuation_info.set_regions_freed(local_free_list.length()); 5702 policy->record_max_rs_lengths(rs_lengths); 5703 policy->cset_regions_freed(); 5704 5705 double end_sec = os::elapsedTime(); 5706 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5707 5708 if (non_young) { 5709 non_young_time_ms += elapsed_ms; 5710 } else { 5711 young_time_ms += elapsed_ms; 5712 } 5713 5714 prepend_to_freelist(&local_free_list); 5715 decrement_summary_bytes(pre_used); 5716 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 5717 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 5718 } 5719 5720 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 5721 private: 5722 FreeRegionList* _free_region_list; 5723 HeapRegionSet* _proxy_set; 5724 HeapRegionSetCount _humongous_regions_removed; 5725 size_t _freed_bytes; 5726 public: 5727 5728 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 5729 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 5730 } 5731 5732 virtual bool doHeapRegion(HeapRegion* r) { 5733 if (!r->is_starts_humongous()) { 5734 return false; 5735 } 5736 5737 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 5738 5739 oop obj = (oop)r->bottom(); 5740 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 5741 5742 // The following checks whether the humongous object is live are sufficient. 5743 // The main additional check (in addition to having a reference from the roots 5744 // or the young gen) is whether the humongous object has a remembered set entry. 5745 // 5746 // A humongous object cannot be live if there is no remembered set for it 5747 // because: 5748 // - there can be no references from within humongous starts regions referencing 5749 // the object because we never allocate other objects into them. 5750 // (I.e. there are no intra-region references that may be missed by the 5751 // remembered set) 5752 // - as soon there is a remembered set entry to the humongous starts region 5753 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 5754 // until the end of a concurrent mark. 5755 // 5756 // It is not required to check whether the object has been found dead by marking 5757 // or not, in fact it would prevent reclamation within a concurrent cycle, as 5758 // all objects allocated during that time are considered live. 5759 // SATB marking is even more conservative than the remembered set. 5760 // So if at this point in the collection there is no remembered set entry, 5761 // nobody has a reference to it. 5762 // At the start of collection we flush all refinement logs, and remembered sets 5763 // are completely up-to-date wrt to references to the humongous object. 5764 // 5765 // Other implementation considerations: 5766 // - never consider object arrays at this time because they would pose 5767 // considerable effort for cleaning up the the remembered sets. This is 5768 // required because stale remembered sets might reference locations that 5769 // are currently allocated into. 5770 uint region_idx = r->hrm_index(); 5771 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 5772 !r->rem_set()->is_empty()) { 5773 5774 if (G1TraceEagerReclaimHumongousObjects) { 5775 gclog_or_tty->print_cr("Live humongous region %u size " SIZE_FORMAT " start " PTR_FORMAT " length %u with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d", 5776 region_idx, 5777 (size_t)obj->size() * HeapWordSize, 5778 p2i(r->bottom()), 5779 r->region_num(), 5780 r->rem_set()->occupied(), 5781 r->rem_set()->strong_code_roots_list_length(), 5782 next_bitmap->isMarked(r->bottom()), 5783 g1h->is_humongous_reclaim_candidate(region_idx), 5784 obj->is_typeArray() 5785 ); 5786 } 5787 5788 return false; 5789 } 5790 5791 guarantee(obj->is_typeArray(), 5792 "Only eagerly reclaiming type arrays is supported, but the object " 5793 PTR_FORMAT " is not.", p2i(r->bottom())); 5794 5795 if (G1TraceEagerReclaimHumongousObjects) { 5796 gclog_or_tty->print_cr("Dead humongous region %u size " SIZE_FORMAT " start " PTR_FORMAT " length %u with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d", 5797 region_idx, 5798 (size_t)obj->size() * HeapWordSize, 5799 p2i(r->bottom()), 5800 r->region_num(), 5801 r->rem_set()->occupied(), 5802 r->rem_set()->strong_code_roots_list_length(), 5803 next_bitmap->isMarked(r->bottom()), 5804 g1h->is_humongous_reclaim_candidate(region_idx), 5805 obj->is_typeArray() 5806 ); 5807 } 5808 // Need to clear mark bit of the humongous object if already set. 5809 if (next_bitmap->isMarked(r->bottom())) { 5810 next_bitmap->clear(r->bottom()); 5811 } 5812 _freed_bytes += r->used(); 5813 r->set_containing_set(NULL); 5814 _humongous_regions_removed.increment(1u, r->capacity()); 5815 g1h->free_humongous_region(r, _free_region_list, false); 5816 5817 return false; 5818 } 5819 5820 HeapRegionSetCount& humongous_free_count() { 5821 return _humongous_regions_removed; 5822 } 5823 5824 size_t bytes_freed() const { 5825 return _freed_bytes; 5826 } 5827 5828 size_t humongous_reclaimed() const { 5829 return _humongous_regions_removed.length(); 5830 } 5831 }; 5832 5833 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 5834 assert_at_safepoint(true); 5835 5836 if (!G1EagerReclaimHumongousObjects || 5837 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) { 5838 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 5839 return; 5840 } 5841 5842 double start_time = os::elapsedTime(); 5843 5844 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 5845 5846 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 5847 heap_region_iterate(&cl); 5848 5849 HeapRegionSetCount empty_set; 5850 remove_from_old_sets(empty_set, cl.humongous_free_count()); 5851 5852 G1HRPrinter* hrp = hr_printer(); 5853 if (hrp->is_active()) { 5854 FreeRegionListIterator iter(&local_cleanup_list); 5855 while (iter.more_available()) { 5856 HeapRegion* hr = iter.get_next(); 5857 hrp->cleanup(hr); 5858 } 5859 } 5860 5861 prepend_to_freelist(&local_cleanup_list); 5862 decrement_summary_bytes(cl.bytes_freed()); 5863 5864 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 5865 cl.humongous_reclaimed()); 5866 } 5867 5868 // This routine is similar to the above but does not record 5869 // any policy statistics or update free lists; we are abandoning 5870 // the current incremental collection set in preparation of a 5871 // full collection. After the full GC we will start to build up 5872 // the incremental collection set again. 5873 // This is only called when we're doing a full collection 5874 // and is immediately followed by the tearing down of the young list. 5875 5876 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 5877 HeapRegion* cur = cs_head; 5878 5879 while (cur != NULL) { 5880 HeapRegion* next = cur->next_in_collection_set(); 5881 assert(cur->in_collection_set(), "bad CS"); 5882 cur->set_next_in_collection_set(NULL); 5883 clear_in_cset(cur); 5884 cur->set_young_index_in_cset(-1); 5885 cur = next; 5886 } 5887 } 5888 5889 void G1CollectedHeap::set_free_regions_coming() { 5890 if (G1ConcRegionFreeingVerbose) { 5891 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 5892 "setting free regions coming"); 5893 } 5894 5895 assert(!free_regions_coming(), "pre-condition"); 5896 _free_regions_coming = true; 5897 } 5898 5899 void G1CollectedHeap::reset_free_regions_coming() { 5900 assert(free_regions_coming(), "pre-condition"); 5901 5902 { 5903 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5904 _free_regions_coming = false; 5905 SecondaryFreeList_lock->notify_all(); 5906 } 5907 5908 if (G1ConcRegionFreeingVerbose) { 5909 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 5910 "reset free regions coming"); 5911 } 5912 } 5913 5914 void G1CollectedHeap::wait_while_free_regions_coming() { 5915 // Most of the time we won't have to wait, so let's do a quick test 5916 // first before we take the lock. 5917 if (!free_regions_coming()) { 5918 return; 5919 } 5920 5921 if (G1ConcRegionFreeingVerbose) { 5922 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 5923 "waiting for free regions"); 5924 } 5925 5926 { 5927 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5928 while (free_regions_coming()) { 5929 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 5930 } 5931 } 5932 5933 if (G1ConcRegionFreeingVerbose) { 5934 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 5935 "done waiting for free regions"); 5936 } 5937 } 5938 5939 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 5940 return _allocator->is_retained_old_region(hr); 5941 } 5942 5943 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 5944 _young_list->push_region(hr); 5945 } 5946 5947 class NoYoungRegionsClosure: public HeapRegionClosure { 5948 private: 5949 bool _success; 5950 public: 5951 NoYoungRegionsClosure() : _success(true) { } 5952 bool doHeapRegion(HeapRegion* r) { 5953 if (r->is_young()) { 5954 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 5955 p2i(r->bottom()), p2i(r->end())); 5956 _success = false; 5957 } 5958 return false; 5959 } 5960 bool success() { return _success; } 5961 }; 5962 5963 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 5964 bool ret = _young_list->check_list_empty(check_sample); 5965 5966 if (check_heap) { 5967 NoYoungRegionsClosure closure; 5968 heap_region_iterate(&closure); 5969 ret = ret && closure.success(); 5970 } 5971 5972 return ret; 5973 } 5974 5975 class TearDownRegionSetsClosure : public HeapRegionClosure { 5976 private: 5977 HeapRegionSet *_old_set; 5978 5979 public: 5980 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 5981 5982 bool doHeapRegion(HeapRegion* r) { 5983 if (r->is_old()) { 5984 _old_set->remove(r); 5985 } else { 5986 // We ignore free regions, we'll empty the free list afterwards. 5987 // We ignore young regions, we'll empty the young list afterwards. 5988 // We ignore humongous regions, we're not tearing down the 5989 // humongous regions set. 5990 assert(r->is_free() || r->is_young() || r->is_humongous(), 5991 "it cannot be another type"); 5992 } 5993 return false; 5994 } 5995 5996 ~TearDownRegionSetsClosure() { 5997 assert(_old_set->is_empty(), "post-condition"); 5998 } 5999 }; 6000 6001 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6002 assert_at_safepoint(true /* should_be_vm_thread */); 6003 6004 if (!free_list_only) { 6005 TearDownRegionSetsClosure cl(&_old_set); 6006 heap_region_iterate(&cl); 6007 6008 // Note that emptying the _young_list is postponed and instead done as 6009 // the first step when rebuilding the regions sets again. The reason for 6010 // this is that during a full GC string deduplication needs to know if 6011 // a collected region was young or old when the full GC was initiated. 6012 } 6013 _hrm.remove_all_free_regions(); 6014 } 6015 6016 void G1CollectedHeap::increase_used(size_t bytes) { 6017 _summary_bytes_used += bytes; 6018 } 6019 6020 void G1CollectedHeap::decrease_used(size_t bytes) { 6021 assert(_summary_bytes_used >= bytes, 6022 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 6023 _summary_bytes_used, bytes); 6024 _summary_bytes_used -= bytes; 6025 } 6026 6027 void G1CollectedHeap::set_used(size_t bytes) { 6028 _summary_bytes_used = bytes; 6029 } 6030 6031 class RebuildRegionSetsClosure : public HeapRegionClosure { 6032 private: 6033 bool _free_list_only; 6034 HeapRegionSet* _old_set; 6035 HeapRegionManager* _hrm; 6036 size_t _total_used; 6037 6038 public: 6039 RebuildRegionSetsClosure(bool free_list_only, 6040 HeapRegionSet* old_set, HeapRegionManager* hrm) : 6041 _free_list_only(free_list_only), 6042 _old_set(old_set), _hrm(hrm), _total_used(0) { 6043 assert(_hrm->num_free_regions() == 0, "pre-condition"); 6044 if (!free_list_only) { 6045 assert(_old_set->is_empty(), "pre-condition"); 6046 } 6047 } 6048 6049 bool doHeapRegion(HeapRegion* r) { 6050 if (r->is_continues_humongous()) { 6051 return false; 6052 } 6053 6054 if (r->is_empty()) { 6055 // Add free regions to the free list 6056 r->set_free(); 6057 r->set_allocation_context(AllocationContext::system()); 6058 _hrm->insert_into_free_list(r); 6059 } else if (!_free_list_only) { 6060 assert(!r->is_young(), "we should not come across young regions"); 6061 6062 if (r->is_humongous()) { 6063 // We ignore humongous regions. We left the humongous set unchanged. 6064 } else { 6065 // Objects that were compacted would have ended up on regions 6066 // that were previously old or free. Archive regions (which are 6067 // old) will not have been touched. 6068 assert(r->is_free() || r->is_old(), "invariant"); 6069 // We now consider them old, so register as such. Leave 6070 // archive regions set that way, however, while still adding 6071 // them to the old set. 6072 if (!r->is_archive()) { 6073 r->set_old(); 6074 } 6075 _old_set->add(r); 6076 } 6077 _total_used += r->used(); 6078 } 6079 6080 return false; 6081 } 6082 6083 size_t total_used() { 6084 return _total_used; 6085 } 6086 }; 6087 6088 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6089 assert_at_safepoint(true /* should_be_vm_thread */); 6090 6091 if (!free_list_only) { 6092 _young_list->empty_list(); 6093 } 6094 6095 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 6096 heap_region_iterate(&cl); 6097 6098 if (!free_list_only) { 6099 set_used(cl.total_used()); 6100 if (_archive_allocator != NULL) { 6101 _archive_allocator->clear_used(); 6102 } 6103 } 6104 assert(used_unlocked() == recalculate_used(), 6105 "inconsistent used_unlocked(), " 6106 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 6107 used_unlocked(), recalculate_used()); 6108 } 6109 6110 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6111 _refine_cte_cl->set_concurrent(concurrent); 6112 } 6113 6114 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6115 HeapRegion* hr = heap_region_containing(p); 6116 return hr->is_in(p); 6117 } 6118 6119 // Methods for the mutator alloc region 6120 6121 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6122 bool force) { 6123 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6124 assert(!force || g1_policy()->can_expand_young_list(), 6125 "if force is true we should be able to expand the young list"); 6126 bool young_list_full = g1_policy()->is_young_list_full(); 6127 if (force || !young_list_full) { 6128 HeapRegion* new_alloc_region = new_region(word_size, 6129 false /* is_old */, 6130 false /* do_expand */); 6131 if (new_alloc_region != NULL) { 6132 set_region_short_lived_locked(new_alloc_region); 6133 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6134 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6135 return new_alloc_region; 6136 } 6137 } 6138 return NULL; 6139 } 6140 6141 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6142 size_t allocated_bytes) { 6143 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6144 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 6145 6146 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6147 increase_used(allocated_bytes); 6148 _hr_printer.retire(alloc_region); 6149 // We update the eden sizes here, when the region is retired, 6150 // instead of when it's allocated, since this is the point that its 6151 // used space has been recored in _summary_bytes_used. 6152 g1mm()->update_eden_size(); 6153 } 6154 6155 // Methods for the GC alloc regions 6156 6157 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6158 uint count, 6159 InCSetState dest) { 6160 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6161 6162 if (count < g1_policy()->max_regions(dest)) { 6163 const bool is_survivor = (dest.is_young()); 6164 HeapRegion* new_alloc_region = new_region(word_size, 6165 !is_survivor, 6166 true /* do_expand */); 6167 if (new_alloc_region != NULL) { 6168 // We really only need to do this for old regions given that we 6169 // should never scan survivors. But it doesn't hurt to do it 6170 // for survivors too. 6171 new_alloc_region->record_timestamp(); 6172 if (is_survivor) { 6173 new_alloc_region->set_survivor(); 6174 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6175 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6176 } else { 6177 new_alloc_region->set_old(); 6178 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6179 check_bitmaps("Old Region Allocation", new_alloc_region); 6180 } 6181 bool during_im = collector_state()->during_initial_mark_pause(); 6182 new_alloc_region->note_start_of_copying(during_im); 6183 return new_alloc_region; 6184 } 6185 } 6186 return NULL; 6187 } 6188 6189 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6190 size_t allocated_bytes, 6191 InCSetState dest) { 6192 bool during_im = collector_state()->during_initial_mark_pause(); 6193 alloc_region->note_end_of_copying(during_im); 6194 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6195 if (dest.is_young()) { 6196 young_list()->add_survivor_region(alloc_region); 6197 } else { 6198 _old_set.add(alloc_region); 6199 } 6200 _hr_printer.retire(alloc_region); 6201 } 6202 6203 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 6204 bool expanded = false; 6205 uint index = _hrm.find_highest_free(&expanded); 6206 6207 if (index != G1_NO_HRM_INDEX) { 6208 if (expanded) { 6209 ergo_verbose1(ErgoHeapSizing, 6210 "attempt heap expansion", 6211 ergo_format_reason("requested address range outside heap bounds") 6212 ergo_format_byte("region size"), 6213 HeapRegion::GrainWords * HeapWordSize); 6214 } 6215 _hrm.allocate_free_regions_starting_at(index, 1); 6216 return region_at(index); 6217 } 6218 return NULL; 6219 } 6220 6221 // Heap region set verification 6222 6223 class VerifyRegionListsClosure : public HeapRegionClosure { 6224 private: 6225 HeapRegionSet* _old_set; 6226 HeapRegionSet* _humongous_set; 6227 HeapRegionManager* _hrm; 6228 6229 public: 6230 HeapRegionSetCount _old_count; 6231 HeapRegionSetCount _humongous_count; 6232 HeapRegionSetCount _free_count; 6233 6234 VerifyRegionListsClosure(HeapRegionSet* old_set, 6235 HeapRegionSet* humongous_set, 6236 HeapRegionManager* hrm) : 6237 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm), 6238 _old_count(), _humongous_count(), _free_count(){ } 6239 6240 bool doHeapRegion(HeapRegion* hr) { 6241 if (hr->is_continues_humongous()) { 6242 return false; 6243 } 6244 6245 if (hr->is_young()) { 6246 // TODO 6247 } else if (hr->is_starts_humongous()) { 6248 assert(hr->containing_set() == _humongous_set, "Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()); 6249 _humongous_count.increment(1u, hr->capacity()); 6250 } else if (hr->is_empty()) { 6251 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index()); 6252 _free_count.increment(1u, hr->capacity()); 6253 } else if (hr->is_old()) { 6254 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index()); 6255 _old_count.increment(1u, hr->capacity()); 6256 } else { 6257 // There are no other valid region types. Check for one invalid 6258 // one we can identify: pinned without old or humongous set. 6259 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index()); 6260 ShouldNotReachHere(); 6261 } 6262 return false; 6263 } 6264 6265 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) { 6266 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()); 6267 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6268 old_set->total_capacity_bytes(), _old_count.capacity()); 6269 6270 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()); 6271 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6272 humongous_set->total_capacity_bytes(), _humongous_count.capacity()); 6273 6274 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()); 6275 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6276 free_list->total_capacity_bytes(), _free_count.capacity()); 6277 } 6278 }; 6279 6280 void G1CollectedHeap::verify_region_sets() { 6281 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6282 6283 // First, check the explicit lists. 6284 _hrm.verify(); 6285 { 6286 // Given that a concurrent operation might be adding regions to 6287 // the secondary free list we have to take the lock before 6288 // verifying it. 6289 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6290 _secondary_free_list.verify_list(); 6291 } 6292 6293 // If a concurrent region freeing operation is in progress it will 6294 // be difficult to correctly attributed any free regions we come 6295 // across to the correct free list given that they might belong to 6296 // one of several (free_list, secondary_free_list, any local lists, 6297 // etc.). So, if that's the case we will skip the rest of the 6298 // verification operation. Alternatively, waiting for the concurrent 6299 // operation to complete will have a non-trivial effect on the GC's 6300 // operation (no concurrent operation will last longer than the 6301 // interval between two calls to verification) and it might hide 6302 // any issues that we would like to catch during testing. 6303 if (free_regions_coming()) { 6304 return; 6305 } 6306 6307 // Make sure we append the secondary_free_list on the free_list so 6308 // that all free regions we will come across can be safely 6309 // attributed to the free_list. 6310 append_secondary_free_list_if_not_empty_with_lock(); 6311 6312 // Finally, make sure that the region accounting in the lists is 6313 // consistent with what we see in the heap. 6314 6315 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm); 6316 heap_region_iterate(&cl); 6317 cl.verify_counts(&_old_set, &_humongous_set, &_hrm); 6318 } 6319 6320 // Optimized nmethod scanning 6321 6322 class RegisterNMethodOopClosure: public OopClosure { 6323 G1CollectedHeap* _g1h; 6324 nmethod* _nm; 6325 6326 template <class T> void do_oop_work(T* p) { 6327 T heap_oop = oopDesc::load_heap_oop(p); 6328 if (!oopDesc::is_null(heap_oop)) { 6329 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6330 HeapRegion* hr = _g1h->heap_region_containing(obj); 6331 assert(!hr->is_continues_humongous(), 6332 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 6333 " starting at " HR_FORMAT, 6334 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 6335 6336 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 6337 hr->add_strong_code_root_locked(_nm); 6338 } 6339 } 6340 6341 public: 6342 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6343 _g1h(g1h), _nm(nm) {} 6344 6345 void do_oop(oop* p) { do_oop_work(p); } 6346 void do_oop(narrowOop* p) { do_oop_work(p); } 6347 }; 6348 6349 class UnregisterNMethodOopClosure: public OopClosure { 6350 G1CollectedHeap* _g1h; 6351 nmethod* _nm; 6352 6353 template <class T> void do_oop_work(T* p) { 6354 T heap_oop = oopDesc::load_heap_oop(p); 6355 if (!oopDesc::is_null(heap_oop)) { 6356 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6357 HeapRegion* hr = _g1h->heap_region_containing(obj); 6358 assert(!hr->is_continues_humongous(), 6359 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 6360 " starting at " HR_FORMAT, 6361 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 6362 6363 hr->remove_strong_code_root(_nm); 6364 } 6365 } 6366 6367 public: 6368 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6369 _g1h(g1h), _nm(nm) {} 6370 6371 void do_oop(oop* p) { do_oop_work(p); } 6372 void do_oop(narrowOop* p) { do_oop_work(p); } 6373 }; 6374 6375 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6376 CollectedHeap::register_nmethod(nm); 6377 6378 guarantee(nm != NULL, "sanity"); 6379 RegisterNMethodOopClosure reg_cl(this, nm); 6380 nm->oops_do(®_cl); 6381 } 6382 6383 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6384 CollectedHeap::unregister_nmethod(nm); 6385 6386 guarantee(nm != NULL, "sanity"); 6387 UnregisterNMethodOopClosure reg_cl(this, nm); 6388 nm->oops_do(®_cl, true); 6389 } 6390 6391 void G1CollectedHeap::purge_code_root_memory() { 6392 double purge_start = os::elapsedTime(); 6393 G1CodeRootSet::purge(); 6394 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6395 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6396 } 6397 6398 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6399 G1CollectedHeap* _g1h; 6400 6401 public: 6402 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6403 _g1h(g1h) {} 6404 6405 void do_code_blob(CodeBlob* cb) { 6406 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6407 if (nm == NULL) { 6408 return; 6409 } 6410 6411 if (ScavengeRootsInCode) { 6412 _g1h->register_nmethod(nm); 6413 } 6414 } 6415 }; 6416 6417 void G1CollectedHeap::rebuild_strong_code_roots() { 6418 RebuildStrongCodeRootClosure blob_cl(this); 6419 CodeCache::blobs_do(&blob_cl); 6420 }