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 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 431 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 432 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 433 } 434 435 // If could fit into free regions w/o expansion, try. 436 // Otherwise, if can expand, do so. 437 // Otherwise, if using ex regions might help, try with ex given back. 438 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 439 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 440 441 verify_region_sets_optional(); 442 443 uint first = G1_NO_HRM_INDEX; 444 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 445 446 if (obj_regions == 1) { 447 // Only one region to allocate, try to use a fast path by directly allocating 448 // from the free lists. Do not try to expand here, we will potentially do that 449 // later. 450 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 451 if (hr != NULL) { 452 first = hr->hrm_index(); 453 } 454 } else { 455 // We can't allocate humongous regions spanning more than one region while 456 // cleanupComplete() is running, since some of the regions we find to be 457 // empty might not yet be added to the free list. It is not straightforward 458 // to know in which list they are on so that we can remove them. We only 459 // need to do this if we need to allocate more than one region to satisfy the 460 // current humongous allocation request. If we are only allocating one region 461 // we use the one-region region allocation code (see above), that already 462 // potentially waits for regions from the secondary free list. 463 wait_while_free_regions_coming(); 464 append_secondary_free_list_if_not_empty_with_lock(); 465 466 // Policy: Try only empty regions (i.e. already committed first). Maybe we 467 // are lucky enough to find some. 468 first = _hrm.find_contiguous_only_empty(obj_regions); 469 if (first != G1_NO_HRM_INDEX) { 470 _hrm.allocate_free_regions_starting_at(first, obj_regions); 471 } 472 } 473 474 if (first == G1_NO_HRM_INDEX) { 475 // Policy: We could not find enough regions for the humongous object in the 476 // free list. Look through the heap to find a mix of free and uncommitted regions. 477 // If so, try expansion. 478 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 479 if (first != G1_NO_HRM_INDEX) { 480 // We found something. Make sure these regions are committed, i.e. expand 481 // the heap. Alternatively we could do a defragmentation GC. 482 ergo_verbose1(ErgoHeapSizing, 483 "attempt heap expansion", 484 ergo_format_reason("humongous allocation request failed") 485 ergo_format_byte("allocation request"), 486 word_size * HeapWordSize); 487 488 _hrm.expand_at(first, obj_regions); 489 g1_policy()->record_new_heap_size(num_regions()); 490 491 #ifdef ASSERT 492 for (uint i = first; i < first + obj_regions; ++i) { 493 HeapRegion* hr = region_at(i); 494 assert(hr->is_free(), "sanity"); 495 assert(hr->is_empty(), "sanity"); 496 assert(is_on_master_free_list(hr), "sanity"); 497 } 498 #endif 499 _hrm.allocate_free_regions_starting_at(first, obj_regions); 500 } else { 501 // Policy: Potentially trigger a defragmentation GC. 502 } 503 } 504 505 HeapWord* result = NULL; 506 if (first != G1_NO_HRM_INDEX) { 507 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 508 word_size, context); 509 assert(result != NULL, "it should always return a valid result"); 510 511 // A successful humongous object allocation changes the used space 512 // information of the old generation so we need to recalculate the 513 // sizes and update the jstat counters here. 514 g1mm()->update_sizes(); 515 } 516 517 verify_region_sets_optional(); 518 519 return result; 520 } 521 522 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 523 assert_heap_not_locked_and_not_at_safepoint(); 524 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 525 526 uint dummy_gc_count_before; 527 uint dummy_gclocker_retry_count = 0; 528 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 529 } 530 531 HeapWord* 532 G1CollectedHeap::mem_allocate(size_t word_size, 533 bool* gc_overhead_limit_was_exceeded) { 534 assert_heap_not_locked_and_not_at_safepoint(); 535 536 // Loop until the allocation is satisfied, or unsatisfied after GC. 537 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 538 uint gc_count_before; 539 540 HeapWord* result = NULL; 541 if (!is_humongous(word_size)) { 542 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 543 } else { 544 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 545 } 546 if (result != NULL) { 547 return result; 548 } 549 550 // Create the garbage collection operation... 551 VM_G1CollectForAllocation op(gc_count_before, word_size); 552 op.set_allocation_context(AllocationContext::current()); 553 554 // ...and get the VM thread to execute it. 555 VMThread::execute(&op); 556 557 if (op.prologue_succeeded() && op.pause_succeeded()) { 558 // If the operation was successful we'll return the result even 559 // if it is NULL. If the allocation attempt failed immediately 560 // after a Full GC, it's unlikely we'll be able to allocate now. 561 HeapWord* result = op.result(); 562 if (result != NULL && !is_humongous(word_size)) { 563 // Allocations that take place on VM operations do not do any 564 // card dirtying and we have to do it here. We only have to do 565 // this for non-humongous allocations, though. 566 dirty_young_block(result, word_size); 567 } 568 return result; 569 } else { 570 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 571 return NULL; 572 } 573 assert(op.result() == NULL, 574 "the result should be NULL if the VM op did not succeed"); 575 } 576 577 // Give a warning if we seem to be looping forever. 578 if ((QueuedAllocationWarningCount > 0) && 579 (try_count % QueuedAllocationWarningCount == 0)) { 580 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 581 } 582 } 583 584 ShouldNotReachHere(); 585 return NULL; 586 } 587 588 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 589 AllocationContext_t context, 590 uint* gc_count_before_ret, 591 uint* gclocker_retry_count_ret) { 592 // Make sure you read the note in attempt_allocation_humongous(). 593 594 assert_heap_not_locked_and_not_at_safepoint(); 595 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 596 "be called for humongous allocation requests"); 597 598 // We should only get here after the first-level allocation attempt 599 // (attempt_allocation()) failed to allocate. 600 601 // We will loop until a) we manage to successfully perform the 602 // allocation or b) we successfully schedule a collection which 603 // fails to perform the allocation. b) is the only case when we'll 604 // return NULL. 605 HeapWord* result = NULL; 606 for (int try_count = 1; /* we'll return */; try_count += 1) { 607 bool should_try_gc; 608 uint gc_count_before; 609 610 { 611 MutexLockerEx x(Heap_lock); 612 result = _allocator->attempt_allocation_locked(word_size, context); 613 if (result != NULL) { 614 return result; 615 } 616 617 if (GC_locker::is_active_and_needs_gc()) { 618 if (g1_policy()->can_expand_young_list()) { 619 // No need for an ergo verbose message here, 620 // can_expand_young_list() does this when it returns true. 621 result = _allocator->attempt_allocation_force(word_size, context); 622 if (result != NULL) { 623 return result; 624 } 625 } 626 should_try_gc = false; 627 } else { 628 // The GCLocker may not be active but the GCLocker initiated 629 // GC may not yet have been performed (GCLocker::needs_gc() 630 // returns true). In this case we do not try this GC and 631 // wait until the GCLocker initiated GC is performed, and 632 // then retry the allocation. 633 if (GC_locker::needs_gc()) { 634 should_try_gc = false; 635 } else { 636 // Read the GC count while still holding the Heap_lock. 637 gc_count_before = total_collections(); 638 should_try_gc = true; 639 } 640 } 641 } 642 643 if (should_try_gc) { 644 bool succeeded; 645 result = do_collection_pause(word_size, gc_count_before, &succeeded, 646 GCCause::_g1_inc_collection_pause); 647 if (result != NULL) { 648 assert(succeeded, "only way to get back a non-NULL result"); 649 return result; 650 } 651 652 if (succeeded) { 653 // If we get here we successfully scheduled a collection which 654 // failed to allocate. No point in trying to allocate 655 // further. We'll just return NULL. 656 MutexLockerEx x(Heap_lock); 657 *gc_count_before_ret = total_collections(); 658 return NULL; 659 } 660 } else { 661 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 662 MutexLockerEx x(Heap_lock); 663 *gc_count_before_ret = total_collections(); 664 return NULL; 665 } 666 // The GCLocker is either active or the GCLocker initiated 667 // GC has not yet been performed. Stall until it is and 668 // then retry the allocation. 669 GC_locker::stall_until_clear(); 670 (*gclocker_retry_count_ret) += 1; 671 } 672 673 // We can reach here if we were unsuccessful in scheduling a 674 // collection (because another thread beat us to it) or if we were 675 // stalled due to the GC locker. In either can we should retry the 676 // allocation attempt in case another thread successfully 677 // performed a collection and reclaimed enough space. We do the 678 // first attempt (without holding the Heap_lock) here and the 679 // follow-on attempt will be at the start of the next loop 680 // iteration (after taking the Heap_lock). 681 result = _allocator->attempt_allocation(word_size, context); 682 if (result != NULL) { 683 return result; 684 } 685 686 // Give a warning if we seem to be looping forever. 687 if ((QueuedAllocationWarningCount > 0) && 688 (try_count % QueuedAllocationWarningCount == 0)) { 689 warning("G1CollectedHeap::attempt_allocation_slow() " 690 "retries %d times", try_count); 691 } 692 } 693 694 ShouldNotReachHere(); 695 return NULL; 696 } 697 698 void G1CollectedHeap::begin_archive_alloc_range() { 699 assert_at_safepoint(true /* should_be_vm_thread */); 700 if (_archive_allocator == NULL) { 701 _archive_allocator = G1ArchiveAllocator::create_allocator(this); 702 } 703 } 704 705 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 706 // Allocations in archive regions cannot be of a size that would be considered 707 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 708 // may be different at archive-restore time. 709 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 710 } 711 712 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 713 assert_at_safepoint(true /* should_be_vm_thread */); 714 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 715 if (is_archive_alloc_too_large(word_size)) { 716 return NULL; 717 } 718 return _archive_allocator->archive_mem_allocate(word_size); 719 } 720 721 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 722 size_t end_alignment_in_bytes) { 723 assert_at_safepoint(true /* should_be_vm_thread */); 724 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 725 726 // Call complete_archive to do the real work, filling in the MemRegion 727 // array with the archive regions. 728 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 729 delete _archive_allocator; 730 _archive_allocator = NULL; 731 } 732 733 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 734 assert(ranges != NULL, "MemRegion array NULL"); 735 assert(count != 0, "No MemRegions provided"); 736 MemRegion reserved = _hrm.reserved(); 737 for (size_t i = 0; i < count; i++) { 738 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 739 return false; 740 } 741 } 742 return true; 743 } 744 745 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) { 746 assert(!is_init_completed(), "Expect to be called at JVM init time"); 747 assert(ranges != NULL, "MemRegion array NULL"); 748 assert(count != 0, "No MemRegions provided"); 749 MutexLockerEx x(Heap_lock); 750 751 MemRegion reserved = _hrm.reserved(); 752 HeapWord* prev_last_addr = NULL; 753 HeapRegion* prev_last_region = NULL; 754 755 // Temporarily disable pretouching of heap pages. This interface is used 756 // when mmap'ing archived heap data in, so pre-touching is wasted. 757 FlagSetting fs(AlwaysPreTouch, false); 758 759 // Enable archive object checking in G1MarkSweep. We have to let it know 760 // about each archive range, so that objects in those ranges aren't marked. 761 G1MarkSweep::enable_archive_object_check(); 762 763 // For each specified MemRegion range, allocate the corresponding G1 764 // regions and mark them as archive regions. We expect the ranges in 765 // ascending starting address order, without overlap. 766 for (size_t i = 0; i < count; i++) { 767 MemRegion curr_range = ranges[i]; 768 HeapWord* start_address = curr_range.start(); 769 size_t word_size = curr_range.word_size(); 770 HeapWord* last_address = curr_range.last(); 771 size_t commits = 0; 772 773 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 774 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 775 p2i(start_address), p2i(last_address)); 776 guarantee(start_address > prev_last_addr, 777 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 778 p2i(start_address), p2i(prev_last_addr)); 779 prev_last_addr = last_address; 780 781 // Check for ranges that start in the same G1 region in which the previous 782 // range ended, and adjust the start address so we don't try to allocate 783 // the same region again. If the current range is entirely within that 784 // region, skip it, just adjusting the recorded top. 785 HeapRegion* start_region = _hrm.addr_to_region(start_address); 786 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 787 start_address = start_region->end(); 788 if (start_address > last_address) { 789 increase_used(word_size * HeapWordSize); 790 start_region->set_top(last_address + 1); 791 continue; 792 } 793 start_region->set_top(start_address); 794 curr_range = MemRegion(start_address, last_address + 1); 795 start_region = _hrm.addr_to_region(start_address); 796 } 797 798 // Perform the actual region allocation, exiting if it fails. 799 // Then note how much new space we have allocated. 800 if (!_hrm.allocate_containing_regions(curr_range, &commits)) { 801 return false; 802 } 803 increase_used(word_size * HeapWordSize); 804 if (commits != 0) { 805 ergo_verbose1(ErgoHeapSizing, 806 "attempt heap expansion", 807 ergo_format_reason("allocate archive regions") 808 ergo_format_byte("total size"), 809 HeapRegion::GrainWords * HeapWordSize * commits); 810 } 811 812 // Mark each G1 region touched by the range as archive, add it to the old set, 813 // and set the allocation context and top. 814 HeapRegion* curr_region = _hrm.addr_to_region(start_address); 815 HeapRegion* last_region = _hrm.addr_to_region(last_address); 816 prev_last_region = last_region; 817 818 while (curr_region != NULL) { 819 assert(curr_region->is_empty() && !curr_region->is_pinned(), 820 "Region already in use (index %u)", curr_region->hrm_index()); 821 _hr_printer.alloc(curr_region, G1HRPrinter::Archive); 822 curr_region->set_allocation_context(AllocationContext::system()); 823 curr_region->set_archive(); 824 _old_set.add(curr_region); 825 if (curr_region != last_region) { 826 curr_region->set_top(curr_region->end()); 827 curr_region = _hrm.next_region_in_heap(curr_region); 828 } else { 829 curr_region->set_top(last_address + 1); 830 curr_region = NULL; 831 } 832 } 833 834 // Notify mark-sweep of the archive range. 835 G1MarkSweep::set_range_archive(curr_range, true); 836 } 837 return true; 838 } 839 840 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 841 assert(!is_init_completed(), "Expect to be called at JVM init time"); 842 assert(ranges != NULL, "MemRegion array NULL"); 843 assert(count != 0, "No MemRegions provided"); 844 MemRegion reserved = _hrm.reserved(); 845 HeapWord *prev_last_addr = NULL; 846 HeapRegion* prev_last_region = NULL; 847 848 // For each MemRegion, create filler objects, if needed, in the G1 regions 849 // that contain the address range. The address range actually within the 850 // MemRegion will not be modified. That is assumed to have been initialized 851 // elsewhere, probably via an mmap of archived heap data. 852 MutexLockerEx x(Heap_lock); 853 for (size_t i = 0; i < count; i++) { 854 HeapWord* start_address = ranges[i].start(); 855 HeapWord* last_address = ranges[i].last(); 856 857 assert(reserved.contains(start_address) && reserved.contains(last_address), 858 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 859 p2i(start_address), p2i(last_address)); 860 assert(start_address > prev_last_addr, 861 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 862 p2i(start_address), p2i(prev_last_addr)); 863 864 HeapRegion* start_region = _hrm.addr_to_region(start_address); 865 HeapRegion* last_region = _hrm.addr_to_region(last_address); 866 HeapWord* bottom_address = start_region->bottom(); 867 868 // Check for a range beginning in the same region in which the 869 // previous one ended. 870 if (start_region == prev_last_region) { 871 bottom_address = prev_last_addr + 1; 872 } 873 874 // Verify that the regions were all marked as archive regions by 875 // alloc_archive_regions. 876 HeapRegion* curr_region = start_region; 877 while (curr_region != NULL) { 878 guarantee(curr_region->is_archive(), 879 "Expected archive region at index %u", curr_region->hrm_index()); 880 if (curr_region != last_region) { 881 curr_region = _hrm.next_region_in_heap(curr_region); 882 } else { 883 curr_region = NULL; 884 } 885 } 886 887 prev_last_addr = last_address; 888 prev_last_region = last_region; 889 890 // Fill the memory below the allocated range with dummy object(s), 891 // if the region bottom does not match the range start, or if the previous 892 // range ended within the same G1 region, and there is a gap. 893 if (start_address != bottom_address) { 894 size_t fill_size = pointer_delta(start_address, bottom_address); 895 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 896 increase_used(fill_size * HeapWordSize); 897 } 898 } 899 } 900 901 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size, 902 uint* gc_count_before_ret, 903 uint* gclocker_retry_count_ret) { 904 assert_heap_not_locked_and_not_at_safepoint(); 905 assert(!is_humongous(word_size), "attempt_allocation() should not " 906 "be called for humongous allocation requests"); 907 908 AllocationContext_t context = AllocationContext::current(); 909 HeapWord* result = _allocator->attempt_allocation(word_size, context); 910 911 if (result == NULL) { 912 result = attempt_allocation_slow(word_size, 913 context, 914 gc_count_before_ret, 915 gclocker_retry_count_ret); 916 } 917 assert_heap_not_locked(); 918 if (result != NULL) { 919 dirty_young_block(result, word_size); 920 } 921 return result; 922 } 923 924 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 925 assert(!is_init_completed(), "Expect to be called at JVM init time"); 926 assert(ranges != NULL, "MemRegion array NULL"); 927 assert(count != 0, "No MemRegions provided"); 928 MemRegion reserved = _hrm.reserved(); 929 HeapWord* prev_last_addr = NULL; 930 HeapRegion* prev_last_region = NULL; 931 size_t size_used = 0; 932 size_t uncommitted_regions = 0; 933 934 // For each Memregion, free the G1 regions that constitute it, and 935 // notify mark-sweep that the range is no longer to be considered 'archive.' 936 MutexLockerEx x(Heap_lock); 937 for (size_t i = 0; i < count; i++) { 938 HeapWord* start_address = ranges[i].start(); 939 HeapWord* last_address = ranges[i].last(); 940 941 assert(reserved.contains(start_address) && reserved.contains(last_address), 942 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 943 p2i(start_address), p2i(last_address)); 944 assert(start_address > prev_last_addr, 945 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 946 p2i(start_address), p2i(prev_last_addr)); 947 size_used += ranges[i].byte_size(); 948 prev_last_addr = last_address; 949 950 HeapRegion* start_region = _hrm.addr_to_region(start_address); 951 HeapRegion* last_region = _hrm.addr_to_region(last_address); 952 953 // Check for ranges that start in the same G1 region in which the previous 954 // range ended, and adjust the start address so we don't try to free 955 // the same region again. If the current range is entirely within that 956 // region, skip it. 957 if (start_region == prev_last_region) { 958 start_address = start_region->end(); 959 if (start_address > last_address) { 960 continue; 961 } 962 start_region = _hrm.addr_to_region(start_address); 963 } 964 prev_last_region = last_region; 965 966 // After verifying that each region was marked as an archive region by 967 // alloc_archive_regions, set it free and empty and uncommit it. 968 HeapRegion* curr_region = start_region; 969 while (curr_region != NULL) { 970 guarantee(curr_region->is_archive(), 971 "Expected archive region at index %u", curr_region->hrm_index()); 972 uint curr_index = curr_region->hrm_index(); 973 _old_set.remove(curr_region); 974 curr_region->set_free(); 975 curr_region->set_top(curr_region->bottom()); 976 if (curr_region != last_region) { 977 curr_region = _hrm.next_region_in_heap(curr_region); 978 } else { 979 curr_region = NULL; 980 } 981 _hrm.shrink_at(curr_index, 1); 982 uncommitted_regions++; 983 } 984 985 // Notify mark-sweep that this is no longer an archive range. 986 G1MarkSweep::set_range_archive(ranges[i], false); 987 } 988 989 if (uncommitted_regions != 0) { 990 ergo_verbose1(ErgoHeapSizing, 991 "attempt heap shrinking", 992 ergo_format_reason("uncommitted archive regions") 993 ergo_format_byte("total size"), 994 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 995 } 996 decrease_used(size_used); 997 } 998 999 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 1000 uint* gc_count_before_ret, 1001 uint* gclocker_retry_count_ret) { 1002 // The structure of this method has a lot of similarities to 1003 // attempt_allocation_slow(). The reason these two were not merged 1004 // into a single one is that such a method would require several "if 1005 // allocation is not humongous do this, otherwise do that" 1006 // conditional paths which would obscure its flow. In fact, an early 1007 // version of this code did use a unified method which was harder to 1008 // follow and, as a result, it had subtle bugs that were hard to 1009 // track down. So keeping these two methods separate allows each to 1010 // be more readable. It will be good to keep these two in sync as 1011 // much as possible. 1012 1013 assert_heap_not_locked_and_not_at_safepoint(); 1014 assert(is_humongous(word_size), "attempt_allocation_humongous() " 1015 "should only be called for humongous allocations"); 1016 1017 // Humongous objects can exhaust the heap quickly, so we should check if we 1018 // need to start a marking cycle at each humongous object allocation. We do 1019 // the check before we do the actual allocation. The reason for doing it 1020 // before the allocation is that we avoid having to keep track of the newly 1021 // allocated memory while we do a GC. 1022 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1023 word_size)) { 1024 collect(GCCause::_g1_humongous_allocation); 1025 } 1026 1027 // We will loop until a) we manage to successfully perform the 1028 // allocation or b) we successfully schedule a collection which 1029 // fails to perform the allocation. b) is the only case when we'll 1030 // return NULL. 1031 HeapWord* result = NULL; 1032 for (int try_count = 1; /* we'll return */; try_count += 1) { 1033 bool should_try_gc; 1034 uint gc_count_before; 1035 1036 { 1037 MutexLockerEx x(Heap_lock); 1038 1039 // Given that humongous objects are not allocated in young 1040 // regions, we'll first try to do the allocation without doing a 1041 // collection hoping that there's enough space in the heap. 1042 result = humongous_obj_allocate(word_size, AllocationContext::current()); 1043 if (result != NULL) { 1044 g1_policy()->add_last_old_allocated_bytes(humongous_obj_size_in_regions(word_size) * HeapRegion::GrainBytes); 1045 return result; 1046 } 1047 1048 if (GC_locker::is_active_and_needs_gc()) { 1049 should_try_gc = false; 1050 } else { 1051 // The GCLocker may not be active but the GCLocker initiated 1052 // GC may not yet have been performed (GCLocker::needs_gc() 1053 // returns true). In this case we do not try this GC and 1054 // wait until the GCLocker initiated GC is performed, and 1055 // then retry the allocation. 1056 if (GC_locker::needs_gc()) { 1057 should_try_gc = false; 1058 } else { 1059 // Read the GC count while still holding the Heap_lock. 1060 gc_count_before = total_collections(); 1061 should_try_gc = true; 1062 } 1063 } 1064 } 1065 1066 if (should_try_gc) { 1067 // If we failed to allocate the humongous object, we should try to 1068 // do a collection pause (if we're allowed) in case it reclaims 1069 // enough space for the allocation to succeed after the pause. 1070 1071 bool succeeded; 1072 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1073 GCCause::_g1_humongous_allocation); 1074 if (result != NULL) { 1075 assert(succeeded, "only way to get back a non-NULL result"); 1076 return result; 1077 } 1078 1079 if (succeeded) { 1080 // If we get here we successfully scheduled a collection which 1081 // failed to allocate. No point in trying to allocate 1082 // further. We'll just return NULL. 1083 MutexLockerEx x(Heap_lock); 1084 *gc_count_before_ret = total_collections(); 1085 return NULL; 1086 } 1087 } else { 1088 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1089 MutexLockerEx x(Heap_lock); 1090 *gc_count_before_ret = total_collections(); 1091 return NULL; 1092 } 1093 // The GCLocker is either active or the GCLocker initiated 1094 // GC has not yet been performed. Stall until it is and 1095 // then retry the allocation. 1096 GC_locker::stall_until_clear(); 1097 (*gclocker_retry_count_ret) += 1; 1098 } 1099 1100 // We can reach here if we were unsuccessful in scheduling a 1101 // collection (because another thread beat us to it) or if we were 1102 // stalled due to the GC locker. In either can we should retry the 1103 // allocation attempt in case another thread successfully 1104 // performed a collection and reclaimed enough space. Give a 1105 // warning if we seem to be looping forever. 1106 1107 if ((QueuedAllocationWarningCount > 0) && 1108 (try_count % QueuedAllocationWarningCount == 0)) { 1109 warning("G1CollectedHeap::attempt_allocation_humongous() " 1110 "retries %d times", try_count); 1111 } 1112 } 1113 1114 ShouldNotReachHere(); 1115 return NULL; 1116 } 1117 1118 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1119 AllocationContext_t context, 1120 bool expect_null_mutator_alloc_region) { 1121 assert_at_safepoint(true /* should_be_vm_thread */); 1122 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region, 1123 "the current alloc region was unexpectedly found to be non-NULL"); 1124 1125 if (!is_humongous(word_size)) { 1126 return _allocator->attempt_allocation_locked(word_size, context); 1127 } else { 1128 HeapWord* result = humongous_obj_allocate(word_size, context); 1129 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1130 collector_state()->set_initiate_conc_mark_if_possible(true); 1131 } 1132 return result; 1133 } 1134 1135 ShouldNotReachHere(); 1136 } 1137 1138 class PostMCRemSetClearClosure: public HeapRegionClosure { 1139 G1CollectedHeap* _g1h; 1140 ModRefBarrierSet* _mr_bs; 1141 public: 1142 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1143 _g1h(g1h), _mr_bs(mr_bs) {} 1144 1145 bool doHeapRegion(HeapRegion* r) { 1146 HeapRegionRemSet* hrrs = r->rem_set(); 1147 1148 if (r->is_continues_humongous()) { 1149 // We'll assert that the strong code root list and RSet is empty 1150 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1151 assert(hrrs->occupied() == 0, "RSet should be empty"); 1152 return false; 1153 } 1154 1155 _g1h->reset_gc_time_stamps(r); 1156 hrrs->clear(); 1157 // You might think here that we could clear just the cards 1158 // corresponding to the used region. But no: if we leave a dirty card 1159 // in a region we might allocate into, then it would prevent that card 1160 // from being enqueued, and cause it to be missed. 1161 // Re: the performance cost: we shouldn't be doing full GC anyway! 1162 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1163 1164 return false; 1165 } 1166 }; 1167 1168 void G1CollectedHeap::clear_rsets_post_compaction() { 1169 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1170 heap_region_iterate(&rs_clear); 1171 } 1172 1173 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1174 G1CollectedHeap* _g1h; 1175 UpdateRSOopClosure _cl; 1176 public: 1177 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) : 1178 _cl(g1->g1_rem_set(), worker_i), 1179 _g1h(g1) 1180 { } 1181 1182 bool doHeapRegion(HeapRegion* r) { 1183 if (!r->is_continues_humongous()) { 1184 _cl.set_from(r); 1185 r->oop_iterate(&_cl); 1186 } 1187 return false; 1188 } 1189 }; 1190 1191 class ParRebuildRSTask: public AbstractGangTask { 1192 G1CollectedHeap* _g1; 1193 HeapRegionClaimer _hrclaimer; 1194 1195 public: 1196 ParRebuildRSTask(G1CollectedHeap* g1) : 1197 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {} 1198 1199 void work(uint worker_id) { 1200 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1201 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer); 1202 } 1203 }; 1204 1205 class PostCompactionPrinterClosure: public HeapRegionClosure { 1206 private: 1207 G1HRPrinter* _hr_printer; 1208 public: 1209 bool doHeapRegion(HeapRegion* hr) { 1210 assert(!hr->is_young(), "not expecting to find young regions"); 1211 if (hr->is_free()) { 1212 // We only generate output for non-empty regions. 1213 } else if (hr->is_starts_humongous()) { 1214 if (hr->region_num() == 1) { 1215 // single humongous region 1216 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1217 } else { 1218 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1219 } 1220 } else if (hr->is_continues_humongous()) { 1221 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1222 } else if (hr->is_archive()) { 1223 _hr_printer->post_compaction(hr, G1HRPrinter::Archive); 1224 } else if (hr->is_old()) { 1225 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1226 } else { 1227 ShouldNotReachHere(); 1228 } 1229 return false; 1230 } 1231 1232 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1233 : _hr_printer(hr_printer) { } 1234 }; 1235 1236 void G1CollectedHeap::print_hrm_post_compaction() { 1237 PostCompactionPrinterClosure cl(hr_printer()); 1238 heap_region_iterate(&cl); 1239 } 1240 1241 bool G1CollectedHeap::do_collection(bool explicit_gc, 1242 bool clear_all_soft_refs, 1243 size_t word_size) { 1244 assert_at_safepoint(true /* should_be_vm_thread */); 1245 1246 if (GC_locker::check_active_before_gc()) { 1247 return false; 1248 } 1249 1250 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1251 gc_timer->register_gc_start(); 1252 1253 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1254 GCIdMark gc_id_mark; 1255 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1256 1257 SvcGCMarker sgcm(SvcGCMarker::FULL); 1258 ResourceMark rm; 1259 1260 G1Log::update_level(); 1261 print_heap_before_gc(); 1262 trace_heap_before_gc(gc_tracer); 1263 1264 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1265 1266 verify_region_sets_optional(); 1267 1268 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1269 collector_policy()->should_clear_all_soft_refs(); 1270 1271 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1272 1273 { 1274 IsGCActiveMark x; 1275 1276 // Timing 1277 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1278 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1279 1280 { 1281 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL); 1282 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1283 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1284 1285 g1_policy()->record_full_collection_start(); 1286 1287 // Note: When we have a more flexible GC logging framework that 1288 // allows us to add optional attributes to a GC log record we 1289 // could consider timing and reporting how long we wait in the 1290 // following two methods. 1291 wait_while_free_regions_coming(); 1292 // If we start the compaction before the CM threads finish 1293 // scanning the root regions we might trip them over as we'll 1294 // be moving objects / updating references. So let's wait until 1295 // they are done. By telling them to abort, they should complete 1296 // early. 1297 _cm->root_regions()->abort(); 1298 _cm->root_regions()->wait_until_scan_finished(); 1299 append_secondary_free_list_if_not_empty_with_lock(); 1300 1301 gc_prologue(true); 1302 increment_total_collections(true /* full gc */); 1303 increment_old_marking_cycles_started(); 1304 1305 assert(used() == recalculate_used(), "Should be equal"); 1306 1307 verify_before_gc(); 1308 1309 check_bitmaps("Full GC Start"); 1310 pre_full_gc_dump(gc_timer); 1311 1312 #if defined(COMPILER2) || INCLUDE_JVMCI 1313 DerivedPointerTable::clear(); 1314 #endif 1315 1316 // Disable discovery and empty the discovered lists 1317 // for the CM ref processor. 1318 ref_processor_cm()->disable_discovery(); 1319 ref_processor_cm()->abandon_partial_discovery(); 1320 ref_processor_cm()->verify_no_references_recorded(); 1321 1322 // Abandon current iterations of concurrent marking and concurrent 1323 // refinement, if any are in progress. We have to do this before 1324 // wait_until_scan_finished() below. 1325 concurrent_mark()->abort(); 1326 1327 // Make sure we'll choose a new allocation region afterwards. 1328 _allocator->release_mutator_alloc_region(); 1329 _allocator->abandon_gc_alloc_regions(); 1330 g1_rem_set()->cleanupHRRS(); 1331 1332 // We should call this after we retire any currently active alloc 1333 // regions so that all the ALLOC / RETIRE events are generated 1334 // before the start GC event. 1335 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1336 1337 // We may have added regions to the current incremental collection 1338 // set between the last GC or pause and now. We need to clear the 1339 // incremental collection set and then start rebuilding it afresh 1340 // after this full GC. 1341 abandon_collection_set(g1_policy()->inc_cset_head()); 1342 g1_policy()->clear_incremental_cset(); 1343 g1_policy()->stop_incremental_cset_building(); 1344 1345 tear_down_region_sets(false /* free_list_only */); 1346 collector_state()->set_gcs_are_young(true); 1347 1348 // See the comments in g1CollectedHeap.hpp and 1349 // G1CollectedHeap::ref_processing_init() about 1350 // how reference processing currently works in G1. 1351 1352 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1353 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1354 1355 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1356 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1357 1358 ref_processor_stw()->enable_discovery(); 1359 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1360 1361 // Do collection work 1362 { 1363 HandleMark hm; // Discard invalid handles created during gc 1364 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1365 } 1366 1367 assert(num_free_regions() == 0, "we should not have added any free regions"); 1368 rebuild_region_sets(false /* free_list_only */); 1369 1370 // Enqueue any discovered reference objects that have 1371 // not been removed from the discovered lists. 1372 ref_processor_stw()->enqueue_discovered_references(); 1373 1374 #if defined(COMPILER2) || INCLUDE_JVMCI 1375 DerivedPointerTable::update_pointers(); 1376 #endif 1377 1378 MemoryService::track_memory_usage(); 1379 1380 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1381 ref_processor_stw()->verify_no_references_recorded(); 1382 1383 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1384 ClassLoaderDataGraph::purge(); 1385 MetaspaceAux::verify_metrics(); 1386 1387 // Note: since we've just done a full GC, concurrent 1388 // marking is no longer active. Therefore we need not 1389 // re-enable reference discovery for the CM ref processor. 1390 // That will be done at the start of the next marking cycle. 1391 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1392 ref_processor_cm()->verify_no_references_recorded(); 1393 1394 reset_gc_time_stamp(); 1395 // Since everything potentially moved, we will clear all remembered 1396 // sets, and clear all cards. Later we will rebuild remembered 1397 // sets. We will also reset the GC time stamps of the regions. 1398 clear_rsets_post_compaction(); 1399 check_gc_time_stamps(); 1400 1401 // Resize the heap if necessary. 1402 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1403 1404 if (_hr_printer.is_active()) { 1405 // We should do this after we potentially resize the heap so 1406 // that all the COMMIT / UNCOMMIT events are generated before 1407 // the end GC event. 1408 1409 print_hrm_post_compaction(); 1410 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1411 } 1412 1413 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1414 if (hot_card_cache->use_cache()) { 1415 hot_card_cache->reset_card_counts(); 1416 hot_card_cache->reset_hot_cache(); 1417 } 1418 1419 // Rebuild remembered sets of all regions. 1420 uint n_workers = 1421 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1422 workers()->active_workers(), 1423 Threads::number_of_non_daemon_threads()); 1424 workers()->set_active_workers(n_workers); 1425 1426 ParRebuildRSTask rebuild_rs_task(this); 1427 workers()->run_task(&rebuild_rs_task); 1428 1429 // Rebuild the strong code root lists for each region 1430 rebuild_strong_code_roots(); 1431 1432 if (true) { // FIXME 1433 MetaspaceGC::compute_new_size(); 1434 } 1435 1436 #ifdef TRACESPINNING 1437 ParallelTaskTerminator::print_termination_counts(); 1438 #endif 1439 1440 // Discard all rset updates 1441 JavaThread::dirty_card_queue_set().abandon_logs(); 1442 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1443 1444 _young_list->reset_sampled_info(); 1445 // At this point there should be no regions in the 1446 // entire heap tagged as young. 1447 assert(check_young_list_empty(true /* check_heap */), 1448 "young list should be empty at this point"); 1449 1450 // Update the number of full collections that have been completed. 1451 increment_old_marking_cycles_completed(false /* concurrent */); 1452 1453 _hrm.verify_optional(); 1454 verify_region_sets_optional(); 1455 1456 verify_after_gc(); 1457 1458 // Clear the previous marking bitmap, if needed for bitmap verification. 1459 // Note we cannot do this when we clear the next marking bitmap in 1460 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1461 // objects marked during a full GC against the previous bitmap. 1462 // But we need to clear it before calling check_bitmaps below since 1463 // the full GC has compacted objects and updated TAMS but not updated 1464 // the prev bitmap. 1465 if (G1VerifyBitmaps) { 1466 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1467 } 1468 check_bitmaps("Full GC End"); 1469 1470 // Start a new incremental collection set for the next pause 1471 assert(g1_policy()->collection_set() == NULL, "must be"); 1472 g1_policy()->start_incremental_cset_building(); 1473 1474 clear_cset_fast_test(); 1475 1476 _allocator->init_mutator_alloc_region(); 1477 1478 g1_policy()->record_full_collection_end(); 1479 1480 if (G1Log::fine()) { 1481 g1_policy()->print_heap_transition(); 1482 } 1483 1484 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1485 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1486 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1487 // before any GC notifications are raised. 1488 g1mm()->update_sizes(); 1489 1490 gc_epilogue(true); 1491 } 1492 1493 if (G1Log::finer()) { 1494 g1_policy()->print_detailed_heap_transition(true /* full */); 1495 } 1496 1497 print_heap_after_gc(); 1498 trace_heap_after_gc(gc_tracer); 1499 1500 post_full_gc_dump(gc_timer); 1501 1502 gc_timer->register_gc_end(); 1503 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1504 } 1505 1506 return true; 1507 } 1508 1509 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1510 // do_collection() will return whether it succeeded in performing 1511 // the GC. Currently, there is no facility on the 1512 // do_full_collection() API to notify the caller than the collection 1513 // did not succeed (e.g., because it was locked out by the GC 1514 // locker). So, right now, we'll ignore the return value. 1515 bool dummy = do_collection(true, /* explicit_gc */ 1516 clear_all_soft_refs, 1517 0 /* word_size */); 1518 } 1519 1520 // This code is mostly copied from TenuredGeneration. 1521 void 1522 G1CollectedHeap:: 1523 resize_if_necessary_after_full_collection(size_t word_size) { 1524 // Include the current allocation, if any, and bytes that will be 1525 // pre-allocated to support collections, as "used". 1526 const size_t used_after_gc = used(); 1527 const size_t capacity_after_gc = capacity(); 1528 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1529 1530 // This is enforced in arguments.cpp. 1531 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1532 "otherwise the code below doesn't make sense"); 1533 1534 // We don't have floating point command-line arguments 1535 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1536 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1537 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1538 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1539 1540 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1541 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1542 1543 // We have to be careful here as these two calculations can overflow 1544 // 32-bit size_t's. 1545 double used_after_gc_d = (double) used_after_gc; 1546 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1547 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1548 1549 // Let's make sure that they are both under the max heap size, which 1550 // by default will make them fit into a size_t. 1551 double desired_capacity_upper_bound = (double) max_heap_size; 1552 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1553 desired_capacity_upper_bound); 1554 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1555 desired_capacity_upper_bound); 1556 1557 // We can now safely turn them into size_t's. 1558 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1559 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1560 1561 // This assert only makes sense here, before we adjust them 1562 // with respect to the min and max heap size. 1563 assert(minimum_desired_capacity <= maximum_desired_capacity, 1564 "minimum_desired_capacity = " SIZE_FORMAT ", " 1565 "maximum_desired_capacity = " SIZE_FORMAT, 1566 minimum_desired_capacity, maximum_desired_capacity); 1567 1568 // Should not be greater than the heap max size. No need to adjust 1569 // it with respect to the heap min size as it's a lower bound (i.e., 1570 // we'll try to make the capacity larger than it, not smaller). 1571 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1572 // Should not be less than the heap min size. No need to adjust it 1573 // with respect to the heap max size as it's an upper bound (i.e., 1574 // we'll try to make the capacity smaller than it, not greater). 1575 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1576 1577 if (capacity_after_gc < minimum_desired_capacity) { 1578 // Don't expand unless it's significant 1579 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1580 ergo_verbose4(ErgoHeapSizing, 1581 "attempt heap expansion", 1582 ergo_format_reason("capacity lower than " 1583 "min desired capacity after Full GC") 1584 ergo_format_byte("capacity") 1585 ergo_format_byte("occupancy") 1586 ergo_format_byte_perc("min desired capacity"), 1587 capacity_after_gc, used_after_gc, 1588 minimum_desired_capacity, (double) MinHeapFreeRatio); 1589 expand(expand_bytes); 1590 1591 // No expansion, now see if we want to shrink 1592 } else if (capacity_after_gc > maximum_desired_capacity) { 1593 // Capacity too large, compute shrinking size 1594 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1595 ergo_verbose4(ErgoHeapSizing, 1596 "attempt heap shrinking", 1597 ergo_format_reason("capacity higher than " 1598 "max desired capacity after Full GC") 1599 ergo_format_byte("capacity") 1600 ergo_format_byte("occupancy") 1601 ergo_format_byte_perc("max desired capacity"), 1602 capacity_after_gc, used_after_gc, 1603 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1604 shrink(shrink_bytes); 1605 } 1606 } 1607 1608 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1609 AllocationContext_t context, 1610 bool do_gc, 1611 bool clear_all_soft_refs, 1612 bool expect_null_mutator_alloc_region, 1613 bool* gc_succeeded) { 1614 *gc_succeeded = true; 1615 // Let's attempt the allocation first. 1616 HeapWord* result = 1617 attempt_allocation_at_safepoint(word_size, 1618 context, 1619 expect_null_mutator_alloc_region); 1620 if (result != NULL) { 1621 assert(*gc_succeeded, "sanity"); 1622 return result; 1623 } 1624 1625 // In a G1 heap, we're supposed to keep allocation from failing by 1626 // incremental pauses. Therefore, at least for now, we'll favor 1627 // expansion over collection. (This might change in the future if we can 1628 // do something smarter than full collection to satisfy a failed alloc.) 1629 result = expand_and_allocate(word_size, context); 1630 if (result != NULL) { 1631 assert(*gc_succeeded, "sanity"); 1632 return result; 1633 } 1634 1635 if (do_gc) { 1636 // Expansion didn't work, we'll try to do a Full GC. 1637 *gc_succeeded = do_collection(false, /* explicit_gc */ 1638 clear_all_soft_refs, 1639 word_size); 1640 } 1641 1642 return NULL; 1643 } 1644 1645 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1646 AllocationContext_t context, 1647 bool* succeeded) { 1648 assert_at_safepoint(true /* should_be_vm_thread */); 1649 1650 // Attempts to allocate followed by Full GC. 1651 HeapWord* result = 1652 satisfy_failed_allocation_helper(word_size, 1653 context, 1654 true, /* do_gc */ 1655 false, /* clear_all_soft_refs */ 1656 false, /* expect_null_mutator_alloc_region */ 1657 succeeded); 1658 1659 if (result != NULL || !*succeeded) { 1660 return result; 1661 } 1662 1663 // Attempts to allocate followed by Full GC that will collect all soft references. 1664 result = satisfy_failed_allocation_helper(word_size, 1665 context, 1666 true, /* do_gc */ 1667 true, /* clear_all_soft_refs */ 1668 true, /* expect_null_mutator_alloc_region */ 1669 succeeded); 1670 1671 if (result != NULL || !*succeeded) { 1672 return result; 1673 } 1674 1675 // Attempts to allocate, no GC 1676 result = satisfy_failed_allocation_helper(word_size, 1677 context, 1678 false, /* do_gc */ 1679 false, /* clear_all_soft_refs */ 1680 true, /* expect_null_mutator_alloc_region */ 1681 succeeded); 1682 1683 if (result != NULL) { 1684 assert(*succeeded, "sanity"); 1685 return result; 1686 } 1687 1688 assert(!collector_policy()->should_clear_all_soft_refs(), 1689 "Flag should have been handled and cleared prior to this point"); 1690 1691 // What else? We might try synchronous finalization later. If the total 1692 // space available is large enough for the allocation, then a more 1693 // complete compaction phase than we've tried so far might be 1694 // appropriate. 1695 assert(*succeeded, "sanity"); 1696 return NULL; 1697 } 1698 1699 // Attempting to expand the heap sufficiently 1700 // to support an allocation of the given "word_size". If 1701 // successful, perform the allocation and return the address of the 1702 // allocated block, or else "NULL". 1703 1704 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1705 assert_at_safepoint(true /* should_be_vm_thread */); 1706 1707 verify_region_sets_optional(); 1708 1709 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1710 ergo_verbose1(ErgoHeapSizing, 1711 "attempt heap expansion", 1712 ergo_format_reason("allocation request failed") 1713 ergo_format_byte("allocation request"), 1714 word_size * HeapWordSize); 1715 if (expand(expand_bytes)) { 1716 _hrm.verify_optional(); 1717 verify_region_sets_optional(); 1718 return attempt_allocation_at_safepoint(word_size, 1719 context, 1720 false /* expect_null_mutator_alloc_region */); 1721 } 1722 return NULL; 1723 } 1724 1725 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) { 1726 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1727 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1728 HeapRegion::GrainBytes); 1729 ergo_verbose2(ErgoHeapSizing, 1730 "expand the heap", 1731 ergo_format_byte("requested expansion amount") 1732 ergo_format_byte("attempted expansion amount"), 1733 expand_bytes, aligned_expand_bytes); 1734 1735 if (is_maximal_no_gc()) { 1736 ergo_verbose0(ErgoHeapSizing, 1737 "did not expand the heap", 1738 ergo_format_reason("heap already fully expanded")); 1739 return false; 1740 } 1741 1742 double expand_heap_start_time_sec = os::elapsedTime(); 1743 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1744 assert(regions_to_expand > 0, "Must expand by at least one region"); 1745 1746 uint expanded_by = _hrm.expand_by(regions_to_expand); 1747 if (expand_time_ms != NULL) { 1748 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1749 } 1750 1751 if (expanded_by > 0) { 1752 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1753 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1754 g1_policy()->record_new_heap_size(num_regions()); 1755 } else { 1756 ergo_verbose0(ErgoHeapSizing, 1757 "did not expand the heap", 1758 ergo_format_reason("heap expansion operation failed")); 1759 // The expansion of the virtual storage space was unsuccessful. 1760 // Let's see if it was because we ran out of swap. 1761 if (G1ExitOnExpansionFailure && 1762 _hrm.available() >= regions_to_expand) { 1763 // We had head room... 1764 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1765 } 1766 } 1767 return regions_to_expand > 0; 1768 } 1769 1770 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1771 size_t aligned_shrink_bytes = 1772 ReservedSpace::page_align_size_down(shrink_bytes); 1773 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1774 HeapRegion::GrainBytes); 1775 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1776 1777 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1778 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1779 1780 ergo_verbose3(ErgoHeapSizing, 1781 "shrink the heap", 1782 ergo_format_byte("requested shrinking amount") 1783 ergo_format_byte("aligned shrinking amount") 1784 ergo_format_byte("attempted shrinking amount"), 1785 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1786 if (num_regions_removed > 0) { 1787 g1_policy()->record_new_heap_size(num_regions()); 1788 } else { 1789 ergo_verbose0(ErgoHeapSizing, 1790 "did not shrink the heap", 1791 ergo_format_reason("heap shrinking operation failed")); 1792 } 1793 } 1794 1795 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1796 verify_region_sets_optional(); 1797 1798 // We should only reach here at the end of a Full GC which means we 1799 // should not not be holding to any GC alloc regions. The method 1800 // below will make sure of that and do any remaining clean up. 1801 _allocator->abandon_gc_alloc_regions(); 1802 1803 // Instead of tearing down / rebuilding the free lists here, we 1804 // could instead use the remove_all_pending() method on free_list to 1805 // remove only the ones that we need to remove. 1806 tear_down_region_sets(true /* free_list_only */); 1807 shrink_helper(shrink_bytes); 1808 rebuild_region_sets(true /* free_list_only */); 1809 1810 _hrm.verify_optional(); 1811 verify_region_sets_optional(); 1812 } 1813 1814 // Public methods. 1815 1816 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1817 CollectedHeap(), 1818 _g1_policy(policy_), 1819 _dirty_card_queue_set(false), 1820 _into_cset_dirty_card_queue_set(false), 1821 _is_alive_closure_cm(this), 1822 _is_alive_closure_stw(this), 1823 _ref_processor_cm(NULL), 1824 _ref_processor_stw(NULL), 1825 _bot_shared(NULL), 1826 _cg1r(NULL), 1827 _g1mm(NULL), 1828 _refine_cte_cl(NULL), 1829 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1830 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1831 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1832 _humongous_reclaim_candidates(), 1833 _has_humongous_reclaim_candidates(false), 1834 _archive_allocator(NULL), 1835 _free_regions_coming(false), 1836 _young_list(new YoungList(this)), 1837 _gc_time_stamp(0), 1838 _summary_bytes_used(0), 1839 _survivor_evac_stats(YoungPLABSize, PLABWeight), 1840 _old_evac_stats(OldPLABSize, PLABWeight), 1841 _expand_heap_after_alloc_failure(true), 1842 _old_marking_cycles_started(0), 1843 _old_marking_cycles_completed(0), 1844 _heap_summary_sent(false), 1845 _in_cset_fast_test(), 1846 _dirty_cards_region_list(NULL), 1847 _worker_cset_start_region(NULL), 1848 _worker_cset_start_region_time_stamp(NULL), 1849 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1850 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1851 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1852 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1853 1854 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1855 /* are_GC_task_threads */true, 1856 /* are_ConcurrentGC_threads */false); 1857 _workers->initialize_workers(); 1858 1859 _allocator = G1Allocator::create_allocator(this); 1860 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1861 1862 // Override the default _filler_array_max_size so that no humongous filler 1863 // objects are created. 1864 _filler_array_max_size = _humongous_object_threshold_in_words; 1865 1866 uint n_queues = ParallelGCThreads; 1867 _task_queues = new RefToScanQueueSet(n_queues); 1868 1869 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1870 assert(n_rem_sets > 0, "Invariant."); 1871 1872 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1873 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC); 1874 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1875 1876 for (uint i = 0; i < n_queues; i++) { 1877 RefToScanQueue* q = new RefToScanQueue(); 1878 q->initialize(); 1879 _task_queues->register_queue(i, q); 1880 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1881 } 1882 clear_cset_start_regions(); 1883 1884 // Initialize the G1EvacuationFailureALot counters and flags. 1885 NOT_PRODUCT(reset_evacuation_should_fail();) 1886 1887 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1888 } 1889 1890 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1891 size_t size, 1892 size_t translation_factor) { 1893 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1894 // Allocate a new reserved space, preferring to use large pages. 1895 ReservedSpace rs(size, preferred_page_size); 1896 G1RegionToSpaceMapper* result = 1897 G1RegionToSpaceMapper::create_mapper(rs, 1898 size, 1899 rs.alignment(), 1900 HeapRegion::GrainBytes, 1901 translation_factor, 1902 mtGC); 1903 if (TracePageSizes) { 1904 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT, 1905 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size); 1906 } 1907 return result; 1908 } 1909 1910 jint G1CollectedHeap::initialize() { 1911 CollectedHeap::pre_initialize(); 1912 os::enable_vtime(); 1913 1914 G1Log::init(); 1915 1916 // Necessary to satisfy locking discipline assertions. 1917 1918 MutexLocker x(Heap_lock); 1919 1920 // We have to initialize the printer before committing the heap, as 1921 // it will be used then. 1922 _hr_printer.set_active(G1PrintHeapRegions); 1923 1924 // While there are no constraints in the GC code that HeapWordSize 1925 // be any particular value, there are multiple other areas in the 1926 // system which believe this to be true (e.g. oop->object_size in some 1927 // cases incorrectly returns the size in wordSize units rather than 1928 // HeapWordSize). 1929 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1930 1931 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1932 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1933 size_t heap_alignment = collector_policy()->heap_alignment(); 1934 1935 // Ensure that the sizes are properly aligned. 1936 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1937 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1938 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1939 1940 _refine_cte_cl = new RefineCardTableEntryClosure(); 1941 1942 jint ecode = JNI_OK; 1943 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode); 1944 if (_cg1r == NULL) { 1945 return ecode; 1946 } 1947 1948 // Reserve the maximum. 1949 1950 // When compressed oops are enabled, the preferred heap base 1951 // is calculated by subtracting the requested size from the 1952 // 32Gb boundary and using the result as the base address for 1953 // heap reservation. If the requested size is not aligned to 1954 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1955 // into the ReservedHeapSpace constructor) then the actual 1956 // base of the reserved heap may end up differing from the 1957 // address that was requested (i.e. the preferred heap base). 1958 // If this happens then we could end up using a non-optimal 1959 // compressed oops mode. 1960 1961 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1962 heap_alignment); 1963 1964 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1965 1966 // Create the barrier set for the entire reserved region. 1967 G1SATBCardTableLoggingModRefBS* bs 1968 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 1969 bs->initialize(); 1970 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 1971 set_barrier_set(bs); 1972 1973 // Also create a G1 rem set. 1974 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 1975 1976 // Carve out the G1 part of the heap. 1977 1978 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1979 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 1980 G1RegionToSpaceMapper* heap_storage = 1981 G1RegionToSpaceMapper::create_mapper(g1_rs, 1982 g1_rs.size(), 1983 page_size, 1984 HeapRegion::GrainBytes, 1985 1, 1986 mtJavaHeap); 1987 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(), 1988 max_byte_size, page_size, 1989 heap_rs.base(), 1990 heap_rs.size()); 1991 heap_storage->set_mapping_changed_listener(&_listener); 1992 1993 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1994 G1RegionToSpaceMapper* bot_storage = 1995 create_aux_memory_mapper("Block offset table", 1996 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize), 1997 G1BlockOffsetSharedArray::heap_map_factor()); 1998 1999 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 2000 G1RegionToSpaceMapper* cardtable_storage = 2001 create_aux_memory_mapper("Card table", 2002 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize), 2003 G1SATBCardTableLoggingModRefBS::heap_map_factor()); 2004 2005 G1RegionToSpaceMapper* card_counts_storage = 2006 create_aux_memory_mapper("Card counts table", 2007 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 2008 G1CardCounts::heap_map_factor()); 2009 2010 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); 2011 G1RegionToSpaceMapper* prev_bitmap_storage = 2012 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor()); 2013 G1RegionToSpaceMapper* next_bitmap_storage = 2014 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor()); 2015 2016 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 2017 g1_barrier_set()->initialize(cardtable_storage); 2018 // Do later initialization work for concurrent refinement. 2019 _cg1r->init(card_counts_storage); 2020 2021 // 6843694 - ensure that the maximum region index can fit 2022 // in the remembered set structures. 2023 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2024 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2025 2026 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2027 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2028 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2029 "too many cards per region"); 2030 2031 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 2032 2033 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage); 2034 2035 { 2036 HeapWord* start = _hrm.reserved().start(); 2037 HeapWord* end = _hrm.reserved().end(); 2038 size_t granularity = HeapRegion::GrainBytes; 2039 2040 _in_cset_fast_test.initialize(start, end, granularity); 2041 _humongous_reclaim_candidates.initialize(start, end, granularity); 2042 } 2043 2044 // Create the ConcurrentMark data structure and thread. 2045 // (Must do this late, so that "max_regions" is defined.) 2046 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 2047 if (_cm == NULL || !_cm->completed_initialization()) { 2048 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 2049 return JNI_ENOMEM; 2050 } 2051 _cmThread = _cm->cmThread(); 2052 2053 // Initialize the from_card cache structure of HeapRegionRemSet. 2054 HeapRegionRemSet::init_heap(max_regions()); 2055 2056 // Now expand into the initial heap size. 2057 if (!expand(init_byte_size)) { 2058 vm_shutdown_during_initialization("Failed to allocate initial heap."); 2059 return JNI_ENOMEM; 2060 } 2061 2062 // Perform any initialization actions delegated to the policy. 2063 g1_policy()->init(); 2064 2065 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2066 SATB_Q_FL_lock, 2067 G1SATBProcessCompletedThreshold, 2068 Shared_SATB_Q_lock); 2069 2070 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 2071 DirtyCardQ_CBL_mon, 2072 DirtyCardQ_FL_lock, 2073 concurrent_g1_refine()->yellow_zone(), 2074 concurrent_g1_refine()->red_zone(), 2075 Shared_DirtyCardQ_lock); 2076 2077 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 2078 DirtyCardQ_CBL_mon, 2079 DirtyCardQ_FL_lock, 2080 -1, // never trigger processing 2081 -1, // no limit on length 2082 Shared_DirtyCardQ_lock, 2083 &JavaThread::dirty_card_queue_set()); 2084 2085 // Initialize the card queue set used to hold cards containing 2086 // references into the collection set. 2087 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 2088 DirtyCardQ_CBL_mon, 2089 DirtyCardQ_FL_lock, 2090 -1, // never trigger processing 2091 -1, // no limit on length 2092 Shared_DirtyCardQ_lock, 2093 &JavaThread::dirty_card_queue_set()); 2094 2095 // Here we allocate the dummy HeapRegion that is required by the 2096 // G1AllocRegion class. 2097 HeapRegion* dummy_region = _hrm.get_dummy_region(); 2098 2099 // We'll re-use the same region whether the alloc region will 2100 // require BOT updates or not and, if it doesn't, then a non-young 2101 // region will complain that it cannot support allocations without 2102 // BOT updates. So we'll tag the dummy region as eden to avoid that. 2103 dummy_region->set_eden(); 2104 // Make sure it's full. 2105 dummy_region->set_top(dummy_region->end()); 2106 G1AllocRegion::setup(this, dummy_region); 2107 2108 _allocator->init_mutator_alloc_region(); 2109 2110 // Do create of the monitoring and management support so that 2111 // values in the heap have been properly initialized. 2112 _g1mm = new G1MonitoringSupport(this); 2113 2114 G1StringDedup::initialize(); 2115 2116 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC); 2117 for (uint i = 0; i < ParallelGCThreads; i++) { 2118 new (&_preserved_objs[i]) OopAndMarkOopStack(); 2119 } 2120 2121 return JNI_OK; 2122 } 2123 2124 void G1CollectedHeap::stop() { 2125 // Stop all concurrent threads. We do this to make sure these threads 2126 // do not continue to execute and access resources (e.g. gclog_or_tty) 2127 // that are destroyed during shutdown. 2128 _cg1r->stop(); 2129 _cmThread->stop(); 2130 if (G1StringDedup::is_enabled()) { 2131 G1StringDedup::stop(); 2132 } 2133 } 2134 2135 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2136 return HeapRegion::max_region_size(); 2137 } 2138 2139 void G1CollectedHeap::post_initialize() { 2140 CollectedHeap::post_initialize(); 2141 ref_processing_init(); 2142 } 2143 2144 void G1CollectedHeap::ref_processing_init() { 2145 // Reference processing in G1 currently works as follows: 2146 // 2147 // * There are two reference processor instances. One is 2148 // used to record and process discovered references 2149 // during concurrent marking; the other is used to 2150 // record and process references during STW pauses 2151 // (both full and incremental). 2152 // * Both ref processors need to 'span' the entire heap as 2153 // the regions in the collection set may be dotted around. 2154 // 2155 // * For the concurrent marking ref processor: 2156 // * Reference discovery is enabled at initial marking. 2157 // * Reference discovery is disabled and the discovered 2158 // references processed etc during remarking. 2159 // * Reference discovery is MT (see below). 2160 // * Reference discovery requires a barrier (see below). 2161 // * Reference processing may or may not be MT 2162 // (depending on the value of ParallelRefProcEnabled 2163 // and ParallelGCThreads). 2164 // * A full GC disables reference discovery by the CM 2165 // ref processor and abandons any entries on it's 2166 // discovered lists. 2167 // 2168 // * For the STW processor: 2169 // * Non MT discovery is enabled at the start of a full GC. 2170 // * Processing and enqueueing during a full GC is non-MT. 2171 // * During a full GC, references are processed after marking. 2172 // 2173 // * Discovery (may or may not be MT) is enabled at the start 2174 // of an incremental evacuation pause. 2175 // * References are processed near the end of a STW evacuation pause. 2176 // * For both types of GC: 2177 // * Discovery is atomic - i.e. not concurrent. 2178 // * Reference discovery will not need a barrier. 2179 2180 MemRegion mr = reserved_region(); 2181 2182 // Concurrent Mark ref processor 2183 _ref_processor_cm = 2184 new ReferenceProcessor(mr, // span 2185 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2186 // mt processing 2187 ParallelGCThreads, 2188 // degree of mt processing 2189 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2190 // mt discovery 2191 MAX2(ParallelGCThreads, ConcGCThreads), 2192 // degree of mt discovery 2193 false, 2194 // Reference discovery is not atomic 2195 &_is_alive_closure_cm); 2196 // is alive closure 2197 // (for efficiency/performance) 2198 2199 // STW ref processor 2200 _ref_processor_stw = 2201 new ReferenceProcessor(mr, // span 2202 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2203 // mt processing 2204 ParallelGCThreads, 2205 // degree of mt processing 2206 (ParallelGCThreads > 1), 2207 // mt discovery 2208 ParallelGCThreads, 2209 // degree of mt discovery 2210 true, 2211 // Reference discovery is atomic 2212 &_is_alive_closure_stw); 2213 // is alive closure 2214 // (for efficiency/performance) 2215 } 2216 2217 CollectorPolicy* G1CollectedHeap::collector_policy() const { 2218 return g1_policy(); 2219 } 2220 2221 size_t G1CollectedHeap::capacity() const { 2222 return _hrm.length() * HeapRegion::GrainBytes; 2223 } 2224 2225 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2226 assert(!hr->is_continues_humongous(), "pre-condition"); 2227 hr->reset_gc_time_stamp(); 2228 if (hr->is_starts_humongous()) { 2229 uint first_index = hr->hrm_index() + 1; 2230 uint last_index = hr->last_hc_index(); 2231 for (uint i = first_index; i < last_index; i += 1) { 2232 HeapRegion* chr = region_at(i); 2233 assert(chr->is_continues_humongous(), "sanity"); 2234 chr->reset_gc_time_stamp(); 2235 } 2236 } 2237 } 2238 2239 #ifndef PRODUCT 2240 2241 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2242 private: 2243 unsigned _gc_time_stamp; 2244 bool _failures; 2245 2246 public: 2247 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2248 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2249 2250 virtual bool doHeapRegion(HeapRegion* hr) { 2251 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2252 if (_gc_time_stamp != region_gc_time_stamp) { 2253 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, " 2254 "expected %d", HR_FORMAT_PARAMS(hr), 2255 region_gc_time_stamp, _gc_time_stamp); 2256 _failures = true; 2257 } 2258 return false; 2259 } 2260 2261 bool failures() { return _failures; } 2262 }; 2263 2264 void G1CollectedHeap::check_gc_time_stamps() { 2265 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2266 heap_region_iterate(&cl); 2267 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2268 } 2269 #endif // PRODUCT 2270 2271 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) { 2272 _cg1r->hot_card_cache()->drain(cl, worker_i); 2273 } 2274 2275 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) { 2276 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2277 size_t n_completed_buffers = 0; 2278 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2279 n_completed_buffers++; 2280 } 2281 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 2282 dcqs.clear_n_completed_buffers(); 2283 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2284 } 2285 2286 // Computes the sum of the storage used by the various regions. 2287 size_t G1CollectedHeap::used() const { 2288 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 2289 if (_archive_allocator != NULL) { 2290 result += _archive_allocator->used(); 2291 } 2292 return result; 2293 } 2294 2295 size_t G1CollectedHeap::used_unlocked() const { 2296 return _summary_bytes_used; 2297 } 2298 2299 class SumUsedClosure: public HeapRegionClosure { 2300 size_t _used; 2301 public: 2302 SumUsedClosure() : _used(0) {} 2303 bool doHeapRegion(HeapRegion* r) { 2304 if (!r->is_continues_humongous()) { 2305 _used += r->used(); 2306 } 2307 return false; 2308 } 2309 size_t result() { return _used; } 2310 }; 2311 2312 size_t G1CollectedHeap::recalculate_used() const { 2313 double recalculate_used_start = os::elapsedTime(); 2314 2315 SumUsedClosure blk; 2316 heap_region_iterate(&blk); 2317 2318 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2319 return blk.result(); 2320 } 2321 2322 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2323 switch (cause) { 2324 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2325 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2326 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 2327 case GCCause::_g1_humongous_allocation: return true; 2328 case GCCause::_update_allocation_context_stats_inc: return true; 2329 case GCCause::_wb_conc_mark: return true; 2330 default: return false; 2331 } 2332 } 2333 2334 #ifndef PRODUCT 2335 void G1CollectedHeap::allocate_dummy_regions() { 2336 // Let's fill up most of the region 2337 size_t word_size = HeapRegion::GrainWords - 1024; 2338 // And as a result the region we'll allocate will be humongous. 2339 guarantee(is_humongous(word_size), "sanity"); 2340 2341 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2342 // Let's use the existing mechanism for the allocation 2343 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2344 AllocationContext::system()); 2345 if (dummy_obj != NULL) { 2346 MemRegion mr(dummy_obj, word_size); 2347 CollectedHeap::fill_with_object(mr); 2348 } else { 2349 // If we can't allocate once, we probably cannot allocate 2350 // again. Let's get out of the loop. 2351 break; 2352 } 2353 } 2354 } 2355 #endif // !PRODUCT 2356 2357 void G1CollectedHeap::increment_old_marking_cycles_started() { 2358 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2359 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2360 "Wrong marking cycle count (started: %d, completed: %d)", 2361 _old_marking_cycles_started, _old_marking_cycles_completed); 2362 2363 _old_marking_cycles_started++; 2364 } 2365 2366 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2367 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2368 2369 // We assume that if concurrent == true, then the caller is a 2370 // concurrent thread that was joined the Suspendible Thread 2371 // Set. If there's ever a cheap way to check this, we should add an 2372 // assert here. 2373 2374 // Given that this method is called at the end of a Full GC or of a 2375 // concurrent cycle, and those can be nested (i.e., a Full GC can 2376 // interrupt a concurrent cycle), the number of full collections 2377 // completed should be either one (in the case where there was no 2378 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2379 // behind the number of full collections started. 2380 2381 // This is the case for the inner caller, i.e. a Full GC. 2382 assert(concurrent || 2383 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2384 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2385 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2386 "is inconsistent with _old_marking_cycles_completed = %u", 2387 _old_marking_cycles_started, _old_marking_cycles_completed); 2388 2389 // This is the case for the outer caller, i.e. the concurrent cycle. 2390 assert(!concurrent || 2391 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2392 "for outer caller (concurrent cycle): " 2393 "_old_marking_cycles_started = %u " 2394 "is inconsistent with _old_marking_cycles_completed = %u", 2395 _old_marking_cycles_started, _old_marking_cycles_completed); 2396 2397 _old_marking_cycles_completed += 1; 2398 2399 // We need to clear the "in_progress" flag in the CM thread before 2400 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2401 // is set) so that if a waiter requests another System.gc() it doesn't 2402 // incorrectly see that a marking cycle is still in progress. 2403 if (concurrent) { 2404 _cmThread->set_idle(); 2405 } 2406 2407 // This notify_all() will ensure that a thread that called 2408 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2409 // and it's waiting for a full GC to finish will be woken up. It is 2410 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2411 FullGCCount_lock->notify_all(); 2412 } 2413 2414 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2415 GCIdMarkAndRestore conc_gc_id_mark; 2416 collector_state()->set_concurrent_cycle_started(true); 2417 _gc_timer_cm->register_gc_start(start_time); 2418 2419 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2420 trace_heap_before_gc(_gc_tracer_cm); 2421 _cmThread->set_gc_id(GCId::current()); 2422 } 2423 2424 void G1CollectedHeap::register_concurrent_cycle_end() { 2425 if (collector_state()->concurrent_cycle_started()) { 2426 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id()); 2427 if (_cm->has_aborted()) { 2428 _gc_tracer_cm->report_concurrent_mode_failure(); 2429 } 2430 2431 _gc_timer_cm->register_gc_end(); 2432 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2433 2434 // Clear state variables to prepare for the next concurrent cycle. 2435 collector_state()->set_concurrent_cycle_started(false); 2436 _heap_summary_sent = false; 2437 } 2438 } 2439 2440 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2441 if (collector_state()->concurrent_cycle_started()) { 2442 // This function can be called when: 2443 // the cleanup pause is run 2444 // the concurrent cycle is aborted before the cleanup pause. 2445 // the concurrent cycle is aborted after the cleanup pause, 2446 // but before the concurrent cycle end has been registered. 2447 // Make sure that we only send the heap information once. 2448 if (!_heap_summary_sent) { 2449 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id()); 2450 trace_heap_after_gc(_gc_tracer_cm); 2451 _heap_summary_sent = true; 2452 } 2453 } 2454 } 2455 2456 void G1CollectedHeap::collect(GCCause::Cause cause) { 2457 assert_heap_not_locked(); 2458 2459 uint gc_count_before; 2460 uint old_marking_count_before; 2461 uint full_gc_count_before; 2462 bool retry_gc; 2463 2464 do { 2465 retry_gc = false; 2466 2467 { 2468 MutexLocker ml(Heap_lock); 2469 2470 // Read the GC count while holding the Heap_lock 2471 gc_count_before = total_collections(); 2472 full_gc_count_before = total_full_collections(); 2473 old_marking_count_before = _old_marking_cycles_started; 2474 } 2475 2476 if (should_do_concurrent_full_gc(cause)) { 2477 // Schedule an initial-mark evacuation pause that will start a 2478 // concurrent cycle. We're setting word_size to 0 which means that 2479 // we are not requesting a post-GC allocation. 2480 VM_G1IncCollectionPause op(gc_count_before, 2481 0, /* word_size */ 2482 true, /* should_initiate_conc_mark */ 2483 g1_policy()->max_pause_time_ms(), 2484 cause); 2485 op.set_allocation_context(AllocationContext::current()); 2486 2487 VMThread::execute(&op); 2488 if (!op.pause_succeeded()) { 2489 if (old_marking_count_before == _old_marking_cycles_started) { 2490 retry_gc = op.should_retry_gc(); 2491 } else { 2492 // A Full GC happened while we were trying to schedule the 2493 // initial-mark GC. No point in starting a new cycle given 2494 // that the whole heap was collected anyway. 2495 } 2496 2497 if (retry_gc) { 2498 if (GC_locker::is_active_and_needs_gc()) { 2499 GC_locker::stall_until_clear(); 2500 } 2501 } 2502 } 2503 } else { 2504 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2505 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2506 2507 // Schedule a standard evacuation pause. We're setting word_size 2508 // to 0 which means that we are not requesting a post-GC allocation. 2509 VM_G1IncCollectionPause op(gc_count_before, 2510 0, /* word_size */ 2511 false, /* should_initiate_conc_mark */ 2512 g1_policy()->max_pause_time_ms(), 2513 cause); 2514 VMThread::execute(&op); 2515 } else { 2516 // Schedule a Full GC. 2517 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2518 VMThread::execute(&op); 2519 } 2520 } 2521 } while (retry_gc); 2522 } 2523 2524 bool G1CollectedHeap::is_in(const void* p) const { 2525 if (_hrm.reserved().contains(p)) { 2526 // Given that we know that p is in the reserved space, 2527 // heap_region_containing_raw() should successfully 2528 // return the containing region. 2529 HeapRegion* hr = heap_region_containing_raw(p); 2530 return hr->is_in(p); 2531 } else { 2532 return false; 2533 } 2534 } 2535 2536 #ifdef ASSERT 2537 bool G1CollectedHeap::is_in_exact(const void* p) const { 2538 bool contains = reserved_region().contains(p); 2539 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2540 if (contains && available) { 2541 return true; 2542 } else { 2543 return false; 2544 } 2545 } 2546 #endif 2547 2548 bool G1CollectedHeap::obj_in_cs(oop obj) { 2549 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj); 2550 return r != NULL && r->in_collection_set(); 2551 } 2552 2553 // Iteration functions. 2554 2555 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2556 2557 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2558 ExtendedOopClosure* _cl; 2559 public: 2560 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2561 bool doHeapRegion(HeapRegion* r) { 2562 if (!r->is_continues_humongous()) { 2563 r->oop_iterate(_cl); 2564 } 2565 return false; 2566 } 2567 }; 2568 2569 // Iterates an ObjectClosure over all objects within a HeapRegion. 2570 2571 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2572 ObjectClosure* _cl; 2573 public: 2574 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2575 bool doHeapRegion(HeapRegion* r) { 2576 if (!r->is_continues_humongous()) { 2577 r->object_iterate(_cl); 2578 } 2579 return false; 2580 } 2581 }; 2582 2583 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2584 IterateObjectClosureRegionClosure blk(cl); 2585 heap_region_iterate(&blk); 2586 } 2587 2588 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2589 _hrm.iterate(cl); 2590 } 2591 2592 void 2593 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, 2594 uint worker_id, 2595 HeapRegionClaimer *hrclaimer, 2596 bool concurrent) const { 2597 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); 2598 } 2599 2600 // Clear the cached CSet starting regions and (more importantly) 2601 // the time stamps. Called when we reset the GC time stamp. 2602 void G1CollectedHeap::clear_cset_start_regions() { 2603 assert(_worker_cset_start_region != NULL, "sanity"); 2604 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2605 2606 for (uint i = 0; i < ParallelGCThreads; i++) { 2607 _worker_cset_start_region[i] = NULL; 2608 _worker_cset_start_region_time_stamp[i] = 0; 2609 } 2610 } 2611 2612 // Given the id of a worker, obtain or calculate a suitable 2613 // starting region for iterating over the current collection set. 2614 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2615 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2616 2617 HeapRegion* result = NULL; 2618 unsigned gc_time_stamp = get_gc_time_stamp(); 2619 2620 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2621 // Cached starting region for current worker was set 2622 // during the current pause - so it's valid. 2623 // Note: the cached starting heap region may be NULL 2624 // (when the collection set is empty). 2625 result = _worker_cset_start_region[worker_i]; 2626 assert(result == NULL || result->in_collection_set(), "sanity"); 2627 return result; 2628 } 2629 2630 // The cached entry was not valid so let's calculate 2631 // a suitable starting heap region for this worker. 2632 2633 // We want the parallel threads to start their collection 2634 // set iteration at different collection set regions to 2635 // avoid contention. 2636 // If we have: 2637 // n collection set regions 2638 // p threads 2639 // Then thread t will start at region floor ((t * n) / p) 2640 2641 result = g1_policy()->collection_set(); 2642 uint cs_size = g1_policy()->cset_region_length(); 2643 uint active_workers = workers()->active_workers(); 2644 2645 uint end_ind = (cs_size * worker_i) / active_workers; 2646 uint start_ind = 0; 2647 2648 if (worker_i > 0 && 2649 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2650 // Previous workers starting region is valid 2651 // so let's iterate from there 2652 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2653 result = _worker_cset_start_region[worker_i - 1]; 2654 } 2655 2656 for (uint i = start_ind; i < end_ind; i++) { 2657 result = result->next_in_collection_set(); 2658 } 2659 2660 // Note: the calculated starting heap region may be NULL 2661 // (when the collection set is empty). 2662 assert(result == NULL || result->in_collection_set(), "sanity"); 2663 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2664 "should be updated only once per pause"); 2665 _worker_cset_start_region[worker_i] = result; 2666 OrderAccess::storestore(); 2667 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2668 return result; 2669 } 2670 2671 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2672 HeapRegion* r = g1_policy()->collection_set(); 2673 while (r != NULL) { 2674 HeapRegion* next = r->next_in_collection_set(); 2675 if (cl->doHeapRegion(r)) { 2676 cl->incomplete(); 2677 return; 2678 } 2679 r = next; 2680 } 2681 } 2682 2683 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2684 HeapRegionClosure *cl) { 2685 if (r == NULL) { 2686 // The CSet is empty so there's nothing to do. 2687 return; 2688 } 2689 2690 assert(r->in_collection_set(), 2691 "Start region must be a member of the collection set."); 2692 HeapRegion* cur = r; 2693 while (cur != NULL) { 2694 HeapRegion* next = cur->next_in_collection_set(); 2695 if (cl->doHeapRegion(cur) && false) { 2696 cl->incomplete(); 2697 return; 2698 } 2699 cur = next; 2700 } 2701 cur = g1_policy()->collection_set(); 2702 while (cur != r) { 2703 HeapRegion* next = cur->next_in_collection_set(); 2704 if (cl->doHeapRegion(cur) && false) { 2705 cl->incomplete(); 2706 return; 2707 } 2708 cur = next; 2709 } 2710 } 2711 2712 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2713 HeapRegion* result = _hrm.next_region_in_heap(from); 2714 while (result != NULL && result->is_pinned()) { 2715 result = _hrm.next_region_in_heap(result); 2716 } 2717 return result; 2718 } 2719 2720 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2721 HeapRegion* hr = heap_region_containing(addr); 2722 return hr->block_start(addr); 2723 } 2724 2725 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2726 HeapRegion* hr = heap_region_containing(addr); 2727 return hr->block_size(addr); 2728 } 2729 2730 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2731 HeapRegion* hr = heap_region_containing(addr); 2732 return hr->block_is_obj(addr); 2733 } 2734 2735 bool G1CollectedHeap::supports_tlab_allocation() const { 2736 return true; 2737 } 2738 2739 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2740 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2741 } 2742 2743 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2744 return young_list()->eden_used_bytes(); 2745 } 2746 2747 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2748 // must be equal to the humongous object limit. 2749 size_t G1CollectedHeap::max_tlab_size() const { 2750 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment); 2751 } 2752 2753 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2754 AllocationContext_t context = AllocationContext::current(); 2755 return _allocator->unsafe_max_tlab_alloc(context); 2756 } 2757 2758 size_t G1CollectedHeap::max_capacity() const { 2759 return _hrm.reserved().byte_size(); 2760 } 2761 2762 jlong G1CollectedHeap::millis_since_last_gc() { 2763 // assert(false, "NYI"); 2764 return 0; 2765 } 2766 2767 void G1CollectedHeap::prepare_for_verify() { 2768 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2769 ensure_parsability(false); 2770 } 2771 g1_rem_set()->prepare_for_verify(); 2772 } 2773 2774 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 2775 VerifyOption vo) { 2776 switch (vo) { 2777 case VerifyOption_G1UsePrevMarking: 2778 return hr->obj_allocated_since_prev_marking(obj); 2779 case VerifyOption_G1UseNextMarking: 2780 return hr->obj_allocated_since_next_marking(obj); 2781 case VerifyOption_G1UseMarkWord: 2782 return false; 2783 default: 2784 ShouldNotReachHere(); 2785 } 2786 return false; // keep some compilers happy 2787 } 2788 2789 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 2790 switch (vo) { 2791 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 2792 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 2793 case VerifyOption_G1UseMarkWord: return NULL; 2794 default: ShouldNotReachHere(); 2795 } 2796 return NULL; // keep some compilers happy 2797 } 2798 2799 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 2800 switch (vo) { 2801 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 2802 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 2803 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 2804 default: ShouldNotReachHere(); 2805 } 2806 return false; // keep some compilers happy 2807 } 2808 2809 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 2810 switch (vo) { 2811 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 2812 case VerifyOption_G1UseNextMarking: return "NTAMS"; 2813 case VerifyOption_G1UseMarkWord: return "NONE"; 2814 default: ShouldNotReachHere(); 2815 } 2816 return NULL; // keep some compilers happy 2817 } 2818 2819 class VerifyRootsClosure: public OopClosure { 2820 private: 2821 G1CollectedHeap* _g1h; 2822 VerifyOption _vo; 2823 bool _failures; 2824 public: 2825 // _vo == UsePrevMarking -> use "prev" marking information, 2826 // _vo == UseNextMarking -> use "next" marking information, 2827 // _vo == UseMarkWord -> use mark word from object header. 2828 VerifyRootsClosure(VerifyOption vo) : 2829 _g1h(G1CollectedHeap::heap()), 2830 _vo(vo), 2831 _failures(false) { } 2832 2833 bool failures() { return _failures; } 2834 2835 template <class T> void do_oop_nv(T* p) { 2836 T heap_oop = oopDesc::load_heap_oop(p); 2837 if (!oopDesc::is_null(heap_oop)) { 2838 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2839 if (_g1h->is_obj_dead_cond(obj, _vo)) { 2840 gclog_or_tty->print_cr("Root location " PTR_FORMAT " " 2841 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj)); 2842 if (_vo == VerifyOption_G1UseMarkWord) { 2843 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark()); 2844 } 2845 obj->print_on(gclog_or_tty); 2846 _failures = true; 2847 } 2848 } 2849 } 2850 2851 void do_oop(oop* p) { do_oop_nv(p); } 2852 void do_oop(narrowOop* p) { do_oop_nv(p); } 2853 }; 2854 2855 class G1VerifyCodeRootOopClosure: public OopClosure { 2856 G1CollectedHeap* _g1h; 2857 OopClosure* _root_cl; 2858 nmethod* _nm; 2859 VerifyOption _vo; 2860 bool _failures; 2861 2862 template <class T> void do_oop_work(T* p) { 2863 // First verify that this root is live 2864 _root_cl->do_oop(p); 2865 2866 if (!G1VerifyHeapRegionCodeRoots) { 2867 // We're not verifying the code roots attached to heap region. 2868 return; 2869 } 2870 2871 // Don't check the code roots during marking verification in a full GC 2872 if (_vo == VerifyOption_G1UseMarkWord) { 2873 return; 2874 } 2875 2876 // Now verify that the current nmethod (which contains p) is 2877 // in the code root list of the heap region containing the 2878 // object referenced by p. 2879 2880 T heap_oop = oopDesc::load_heap_oop(p); 2881 if (!oopDesc::is_null(heap_oop)) { 2882 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2883 2884 // Now fetch the region containing the object 2885 HeapRegion* hr = _g1h->heap_region_containing(obj); 2886 HeapRegionRemSet* hrrs = hr->rem_set(); 2887 // Verify that the strong code root list for this region 2888 // contains the nmethod 2889 if (!hrrs->strong_code_roots_list_contains(_nm)) { 2890 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " " 2891 "from nmethod " PTR_FORMAT " not in strong " 2892 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")", 2893 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end())); 2894 _failures = true; 2895 } 2896 } 2897 } 2898 2899 public: 2900 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 2901 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 2902 2903 void do_oop(oop* p) { do_oop_work(p); } 2904 void do_oop(narrowOop* p) { do_oop_work(p); } 2905 2906 void set_nmethod(nmethod* nm) { _nm = nm; } 2907 bool failures() { return _failures; } 2908 }; 2909 2910 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 2911 G1VerifyCodeRootOopClosure* _oop_cl; 2912 2913 public: 2914 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 2915 _oop_cl(oop_cl) {} 2916 2917 void do_code_blob(CodeBlob* cb) { 2918 nmethod* nm = cb->as_nmethod_or_null(); 2919 if (nm != NULL) { 2920 _oop_cl->set_nmethod(nm); 2921 nm->oops_do(_oop_cl); 2922 } 2923 } 2924 }; 2925 2926 class YoungRefCounterClosure : public OopClosure { 2927 G1CollectedHeap* _g1h; 2928 int _count; 2929 public: 2930 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 2931 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 2932 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 2933 2934 int count() { return _count; } 2935 void reset_count() { _count = 0; }; 2936 }; 2937 2938 class VerifyKlassClosure: public KlassClosure { 2939 YoungRefCounterClosure _young_ref_counter_closure; 2940 OopClosure *_oop_closure; 2941 public: 2942 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 2943 void do_klass(Klass* k) { 2944 k->oops_do(_oop_closure); 2945 2946 _young_ref_counter_closure.reset_count(); 2947 k->oops_do(&_young_ref_counter_closure); 2948 if (_young_ref_counter_closure.count() > 0) { 2949 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)); 2950 } 2951 } 2952 }; 2953 2954 class VerifyLivenessOopClosure: public OopClosure { 2955 G1CollectedHeap* _g1h; 2956 VerifyOption _vo; 2957 public: 2958 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 2959 _g1h(g1h), _vo(vo) 2960 { } 2961 void do_oop(narrowOop *p) { do_oop_work(p); } 2962 void do_oop( oop *p) { do_oop_work(p); } 2963 2964 template <class T> void do_oop_work(T *p) { 2965 oop obj = oopDesc::load_decode_heap_oop(p); 2966 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 2967 "Dead object referenced by a not dead object"); 2968 } 2969 }; 2970 2971 class VerifyObjsInRegionClosure: public ObjectClosure { 2972 private: 2973 G1CollectedHeap* _g1h; 2974 size_t _live_bytes; 2975 HeapRegion *_hr; 2976 VerifyOption _vo; 2977 public: 2978 // _vo == UsePrevMarking -> use "prev" marking information, 2979 // _vo == UseNextMarking -> use "next" marking information, 2980 // _vo == UseMarkWord -> use mark word from object header. 2981 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 2982 : _live_bytes(0), _hr(hr), _vo(vo) { 2983 _g1h = G1CollectedHeap::heap(); 2984 } 2985 void do_object(oop o) { 2986 VerifyLivenessOopClosure isLive(_g1h, _vo); 2987 assert(o != NULL, "Huh?"); 2988 if (!_g1h->is_obj_dead_cond(o, _vo)) { 2989 // If the object is alive according to the mark word, 2990 // then verify that the marking information agrees. 2991 // Note we can't verify the contra-positive of the 2992 // above: if the object is dead (according to the mark 2993 // word), it may not be marked, or may have been marked 2994 // but has since became dead, or may have been allocated 2995 // since the last marking. 2996 if (_vo == VerifyOption_G1UseMarkWord) { 2997 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 2998 } 2999 3000 o->oop_iterate_no_header(&isLive); 3001 if (!_hr->obj_allocated_since_prev_marking(o)) { 3002 size_t obj_size = o->size(); // Make sure we don't overflow 3003 _live_bytes += (obj_size * HeapWordSize); 3004 } 3005 } 3006 } 3007 size_t live_bytes() { return _live_bytes; } 3008 }; 3009 3010 class VerifyArchiveOopClosure: public OopClosure { 3011 public: 3012 VerifyArchiveOopClosure(HeapRegion *hr) { } 3013 void do_oop(narrowOop *p) { do_oop_work(p); } 3014 void do_oop( oop *p) { do_oop_work(p); } 3015 3016 template <class T> void do_oop_work(T *p) { 3017 oop obj = oopDesc::load_decode_heap_oop(p); 3018 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj), 3019 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT, 3020 p2i(p), p2i(obj)); 3021 } 3022 }; 3023 3024 class VerifyArchiveRegionClosure: public ObjectClosure { 3025 public: 3026 VerifyArchiveRegionClosure(HeapRegion *hr) { } 3027 // Verify that all object pointers are to archive regions. 3028 void do_object(oop o) { 3029 VerifyArchiveOopClosure checkOop(NULL); 3030 assert(o != NULL, "Should not be here for NULL oops"); 3031 o->oop_iterate_no_header(&checkOop); 3032 } 3033 }; 3034 3035 class VerifyRegionClosure: public HeapRegionClosure { 3036 private: 3037 bool _par; 3038 VerifyOption _vo; 3039 bool _failures; 3040 public: 3041 // _vo == UsePrevMarking -> use "prev" marking information, 3042 // _vo == UseNextMarking -> use "next" marking information, 3043 // _vo == UseMarkWord -> use mark word from object header. 3044 VerifyRegionClosure(bool par, VerifyOption vo) 3045 : _par(par), 3046 _vo(vo), 3047 _failures(false) {} 3048 3049 bool failures() { 3050 return _failures; 3051 } 3052 3053 bool doHeapRegion(HeapRegion* r) { 3054 // For archive regions, verify there are no heap pointers to 3055 // non-pinned regions. For all others, verify liveness info. 3056 if (r->is_archive()) { 3057 VerifyArchiveRegionClosure verify_oop_pointers(r); 3058 r->object_iterate(&verify_oop_pointers); 3059 return true; 3060 } 3061 if (!r->is_continues_humongous()) { 3062 bool failures = false; 3063 r->verify(_vo, &failures); 3064 if (failures) { 3065 _failures = true; 3066 } else { 3067 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3068 r->object_iterate(¬_dead_yet_cl); 3069 if (_vo != VerifyOption_G1UseNextMarking) { 3070 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3071 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] " 3072 "max_live_bytes " SIZE_FORMAT " " 3073 "< calculated " SIZE_FORMAT, 3074 p2i(r->bottom()), p2i(r->end()), 3075 r->max_live_bytes(), 3076 not_dead_yet_cl.live_bytes()); 3077 _failures = true; 3078 } 3079 } else { 3080 // When vo == UseNextMarking we cannot currently do a sanity 3081 // check on the live bytes as the calculation has not been 3082 // finalized yet. 3083 } 3084 } 3085 } 3086 return false; // stop the region iteration if we hit a failure 3087 } 3088 }; 3089 3090 // This is the task used for parallel verification of the heap regions 3091 3092 class G1ParVerifyTask: public AbstractGangTask { 3093 private: 3094 G1CollectedHeap* _g1h; 3095 VerifyOption _vo; 3096 bool _failures; 3097 HeapRegionClaimer _hrclaimer; 3098 3099 public: 3100 // _vo == UsePrevMarking -> use "prev" marking information, 3101 // _vo == UseNextMarking -> use "next" marking information, 3102 // _vo == UseMarkWord -> use mark word from object header. 3103 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3104 AbstractGangTask("Parallel verify task"), 3105 _g1h(g1h), 3106 _vo(vo), 3107 _failures(false), 3108 _hrclaimer(g1h->workers()->active_workers()) {} 3109 3110 bool failures() { 3111 return _failures; 3112 } 3113 3114 void work(uint worker_id) { 3115 HandleMark hm; 3116 VerifyRegionClosure blk(true, _vo); 3117 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer); 3118 if (blk.failures()) { 3119 _failures = true; 3120 } 3121 } 3122 }; 3123 3124 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3125 if (SafepointSynchronize::is_at_safepoint()) { 3126 assert(Thread::current()->is_VM_thread(), 3127 "Expected to be executed serially by the VM thread at this point"); 3128 3129 if (!silent) { gclog_or_tty->print("Roots "); } 3130 VerifyRootsClosure rootsCl(vo); 3131 VerifyKlassClosure klassCl(this, &rootsCl); 3132 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3133 3134 // We apply the relevant closures to all the oops in the 3135 // system dictionary, class loader data graph, the string table 3136 // and the nmethods in the code cache. 3137 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3138 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3139 3140 { 3141 G1RootProcessor root_processor(this, 1); 3142 root_processor.process_all_roots(&rootsCl, 3143 &cldCl, 3144 &blobsCl); 3145 } 3146 3147 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3148 3149 if (vo != VerifyOption_G1UseMarkWord) { 3150 // If we're verifying during a full GC then the region sets 3151 // will have been torn down at the start of the GC. Therefore 3152 // verifying the region sets will fail. So we only verify 3153 // the region sets when not in a full GC. 3154 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3155 verify_region_sets(); 3156 } 3157 3158 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3159 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3160 3161 G1ParVerifyTask task(this, vo); 3162 workers()->run_task(&task); 3163 if (task.failures()) { 3164 failures = true; 3165 } 3166 3167 } else { 3168 VerifyRegionClosure blk(false, vo); 3169 heap_region_iterate(&blk); 3170 if (blk.failures()) { 3171 failures = true; 3172 } 3173 } 3174 3175 if (G1StringDedup::is_enabled()) { 3176 if (!silent) gclog_or_tty->print("StrDedup "); 3177 G1StringDedup::verify(); 3178 } 3179 3180 if (failures) { 3181 gclog_or_tty->print_cr("Heap:"); 3182 // It helps to have the per-region information in the output to 3183 // help us track down what went wrong. This is why we call 3184 // print_extended_on() instead of print_on(). 3185 print_extended_on(gclog_or_tty); 3186 gclog_or_tty->cr(); 3187 gclog_or_tty->flush(); 3188 } 3189 guarantee(!failures, "there should not have been any failures"); 3190 } else { 3191 if (!silent) { 3192 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3193 if (G1StringDedup::is_enabled()) { 3194 gclog_or_tty->print(", StrDedup"); 3195 } 3196 gclog_or_tty->print(") "); 3197 } 3198 } 3199 } 3200 3201 void G1CollectedHeap::verify(bool silent) { 3202 verify(silent, VerifyOption_G1UsePrevMarking); 3203 } 3204 3205 double G1CollectedHeap::verify(bool guard, const char* msg) { 3206 double verify_time_ms = 0.0; 3207 3208 if (guard && total_collections() >= VerifyGCStartAt) { 3209 double verify_start = os::elapsedTime(); 3210 HandleMark hm; // Discard invalid handles created during verification 3211 prepare_for_verify(); 3212 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3213 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3214 } 3215 3216 return verify_time_ms; 3217 } 3218 3219 void G1CollectedHeap::verify_before_gc() { 3220 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3221 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3222 } 3223 3224 void G1CollectedHeap::verify_after_gc() { 3225 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3226 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3227 } 3228 3229 class PrintRegionClosure: public HeapRegionClosure { 3230 outputStream* _st; 3231 public: 3232 PrintRegionClosure(outputStream* st) : _st(st) {} 3233 bool doHeapRegion(HeapRegion* r) { 3234 r->print_on(_st); 3235 return false; 3236 } 3237 }; 3238 3239 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3240 const HeapRegion* hr, 3241 const VerifyOption vo) const { 3242 switch (vo) { 3243 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3244 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3245 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive(); 3246 default: ShouldNotReachHere(); 3247 } 3248 return false; // keep some compilers happy 3249 } 3250 3251 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3252 const VerifyOption vo) const { 3253 switch (vo) { 3254 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3255 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3256 case VerifyOption_G1UseMarkWord: { 3257 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj); 3258 return !obj->is_gc_marked() && !hr->is_archive(); 3259 } 3260 default: ShouldNotReachHere(); 3261 } 3262 return false; // keep some compilers happy 3263 } 3264 3265 void G1CollectedHeap::print_on(outputStream* st) const { 3266 st->print(" %-20s", "garbage-first heap"); 3267 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3268 capacity()/K, used_unlocked()/K); 3269 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")", 3270 p2i(_hrm.reserved().start()), 3271 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords), 3272 p2i(_hrm.reserved().end())); 3273 st->cr(); 3274 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3275 uint young_regions = _young_list->length(); 3276 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3277 (size_t) young_regions * HeapRegion::GrainBytes / K); 3278 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3279 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3280 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3281 st->cr(); 3282 MetaspaceAux::print_on(st); 3283 } 3284 3285 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3286 print_on(st); 3287 3288 // Print the per-region information. 3289 st->cr(); 3290 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, " 3291 "HS=humongous(starts), HC=humongous(continues), " 3292 "CS=collection set, F=free, A=archive, TS=gc time stamp, " 3293 "PTAMS=previous top-at-mark-start, " 3294 "NTAMS=next top-at-mark-start)"); 3295 PrintRegionClosure blk(st); 3296 heap_region_iterate(&blk); 3297 } 3298 3299 void G1CollectedHeap::print_on_error(outputStream* st) const { 3300 this->CollectedHeap::print_on_error(st); 3301 3302 if (_cm != NULL) { 3303 st->cr(); 3304 _cm->print_on_error(st); 3305 } 3306 } 3307 3308 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3309 workers()->print_worker_threads_on(st); 3310 _cmThread->print_on(st); 3311 st->cr(); 3312 _cm->print_worker_threads_on(st); 3313 _cg1r->print_worker_threads_on(st); 3314 if (G1StringDedup::is_enabled()) { 3315 G1StringDedup::print_worker_threads_on(st); 3316 } 3317 } 3318 3319 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3320 workers()->threads_do(tc); 3321 tc->do_thread(_cmThread); 3322 _cg1r->threads_do(tc); 3323 if (G1StringDedup::is_enabled()) { 3324 G1StringDedup::threads_do(tc); 3325 } 3326 } 3327 3328 void G1CollectedHeap::print_tracing_info() const { 3329 // We'll overload this to mean "trace GC pause statistics." 3330 if (TraceYoungGenTime || TraceOldGenTime) { 3331 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3332 // to that. 3333 g1_policy()->print_tracing_info(); 3334 } 3335 if (G1SummarizeRSetStats) { 3336 g1_rem_set()->print_summary_info(); 3337 } 3338 if (G1SummarizeConcMark) { 3339 concurrent_mark()->print_summary_info(); 3340 } 3341 g1_policy()->print_yg_surv_rate_info(); 3342 } 3343 3344 #ifndef PRODUCT 3345 // Helpful for debugging RSet issues. 3346 3347 class PrintRSetsClosure : public HeapRegionClosure { 3348 private: 3349 const char* _msg; 3350 size_t _occupied_sum; 3351 3352 public: 3353 bool doHeapRegion(HeapRegion* r) { 3354 HeapRegionRemSet* hrrs = r->rem_set(); 3355 size_t occupied = hrrs->occupied(); 3356 _occupied_sum += occupied; 3357 3358 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT, 3359 HR_FORMAT_PARAMS(r)); 3360 if (occupied == 0) { 3361 gclog_or_tty->print_cr(" RSet is empty"); 3362 } else { 3363 hrrs->print(); 3364 } 3365 gclog_or_tty->print_cr("----------"); 3366 return false; 3367 } 3368 3369 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3370 gclog_or_tty->cr(); 3371 gclog_or_tty->print_cr("========================================"); 3372 gclog_or_tty->print_cr("%s", msg); 3373 gclog_or_tty->cr(); 3374 } 3375 3376 ~PrintRSetsClosure() { 3377 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 3378 gclog_or_tty->print_cr("========================================"); 3379 gclog_or_tty->cr(); 3380 } 3381 }; 3382 3383 void G1CollectedHeap::print_cset_rsets() { 3384 PrintRSetsClosure cl("Printing CSet RSets"); 3385 collection_set_iterate(&cl); 3386 } 3387 3388 void G1CollectedHeap::print_all_rsets() { 3389 PrintRSetsClosure cl("Printing All RSets");; 3390 heap_region_iterate(&cl); 3391 } 3392 #endif // PRODUCT 3393 3394 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 3395 YoungList* young_list = heap()->young_list(); 3396 3397 size_t eden_used_bytes = young_list->eden_used_bytes(); 3398 size_t survivor_used_bytes = young_list->survivor_used_bytes(); 3399 3400 size_t eden_capacity_bytes = 3401 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 3402 3403 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 3404 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes); 3405 } 3406 3407 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 3408 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 3409 stats->unused(), stats->used(), stats->region_end_waste(), 3410 stats->regions_filled(), stats->direct_allocated(), 3411 stats->failure_used(), stats->failure_waste()); 3412 } 3413 3414 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 3415 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 3416 gc_tracer->report_gc_heap_summary(when, heap_summary); 3417 3418 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 3419 gc_tracer->report_metaspace_summary(when, metaspace_summary); 3420 } 3421 3422 3423 G1CollectedHeap* G1CollectedHeap::heap() { 3424 CollectedHeap* heap = Universe::heap(); 3425 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 3426 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); 3427 return (G1CollectedHeap*)heap; 3428 } 3429 3430 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3431 // always_do_update_barrier = false; 3432 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3433 // Fill TLAB's and such 3434 accumulate_statistics_all_tlabs(); 3435 ensure_parsability(true); 3436 3437 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3438 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3439 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3440 } 3441 } 3442 3443 void G1CollectedHeap::gc_epilogue(bool full) { 3444 3445 if (G1SummarizeRSetStats && 3446 (G1SummarizeRSetStatsPeriod > 0) && 3447 // we are at the end of the GC. Total collections has already been increased. 3448 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3449 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3450 } 3451 3452 // FIXME: what is this about? 3453 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3454 // is set. 3455 #if defined(COMPILER2) || INCLUDE_JVMCI 3456 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 3457 #endif 3458 // always_do_update_barrier = true; 3459 3460 resize_all_tlabs(); 3461 allocation_context_stats().update(full); 3462 3463 // We have just completed a GC. Update the soft reference 3464 // policy with the new heap occupancy 3465 Universe::update_heap_info_at_gc(); 3466 } 3467 3468 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3469 uint gc_count_before, 3470 bool* succeeded, 3471 GCCause::Cause gc_cause) { 3472 assert_heap_not_locked_and_not_at_safepoint(); 3473 g1_policy()->record_stop_world_start(); 3474 VM_G1IncCollectionPause op(gc_count_before, 3475 word_size, 3476 false, /* should_initiate_conc_mark */ 3477 g1_policy()->max_pause_time_ms(), 3478 gc_cause); 3479 3480 op.set_allocation_context(AllocationContext::current()); 3481 VMThread::execute(&op); 3482 3483 HeapWord* result = op.result(); 3484 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3485 assert(result == NULL || ret_succeeded, 3486 "the result should be NULL if the VM did not succeed"); 3487 *succeeded = ret_succeeded; 3488 3489 assert_heap_not_locked(); 3490 return result; 3491 } 3492 3493 void 3494 G1CollectedHeap::doConcurrentMark() { 3495 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3496 if (!_cmThread->in_progress()) { 3497 _cmThread->set_started(); 3498 CGC_lock->notify(); 3499 } 3500 } 3501 3502 size_t G1CollectedHeap::pending_card_num() { 3503 size_t extra_cards = 0; 3504 JavaThread *curr = Threads::first(); 3505 while (curr != NULL) { 3506 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3507 extra_cards += dcq.size(); 3508 curr = curr->next(); 3509 } 3510 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3511 size_t buffer_size = dcqs.buffer_size(); 3512 size_t buffer_num = dcqs.completed_buffers_num(); 3513 3514 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3515 // in bytes - not the number of 'entries'. We need to convert 3516 // into a number of cards. 3517 return (buffer_size * buffer_num + extra_cards) / oopSize; 3518 } 3519 3520 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3521 private: 3522 size_t _total_humongous; 3523 size_t _candidate_humongous; 3524 3525 DirtyCardQueue _dcq; 3526 3527 // We don't nominate objects with many remembered set entries, on 3528 // the assumption that such objects are likely still live. 3529 bool is_remset_small(HeapRegion* region) const { 3530 HeapRegionRemSet* const rset = region->rem_set(); 3531 return G1EagerReclaimHumongousObjectsWithStaleRefs 3532 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) 3533 : rset->is_empty(); 3534 } 3535 3536 bool is_typeArray_region(HeapRegion* region) const { 3537 return oop(region->bottom())->is_typeArray(); 3538 } 3539 3540 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { 3541 assert(region->is_starts_humongous(), "Must start a humongous object"); 3542 3543 // Candidate selection must satisfy the following constraints 3544 // while concurrent marking is in progress: 3545 // 3546 // * In order to maintain SATB invariants, an object must not be 3547 // reclaimed if it was allocated before the start of marking and 3548 // has not had its references scanned. Such an object must have 3549 // its references (including type metadata) scanned to ensure no 3550 // live objects are missed by the marking process. Objects 3551 // allocated after the start of concurrent marking don't need to 3552 // be scanned. 3553 // 3554 // * An object must not be reclaimed if it is on the concurrent 3555 // mark stack. Objects allocated after the start of concurrent 3556 // marking are never pushed on the mark stack. 3557 // 3558 // Nominating only objects allocated after the start of concurrent 3559 // marking is sufficient to meet both constraints. This may miss 3560 // some objects that satisfy the constraints, but the marking data 3561 // structures don't support efficiently performing the needed 3562 // additional tests or scrubbing of the mark stack. 3563 // 3564 // However, we presently only nominate is_typeArray() objects. 3565 // A humongous object containing references induces remembered 3566 // set entries on other regions. In order to reclaim such an 3567 // object, those remembered sets would need to be cleaned up. 3568 // 3569 // We also treat is_typeArray() objects specially, allowing them 3570 // to be reclaimed even if allocated before the start of 3571 // concurrent mark. For this we rely on mark stack insertion to 3572 // exclude is_typeArray() objects, preventing reclaiming an object 3573 // that is in the mark stack. We also rely on the metadata for 3574 // such objects to be built-in and so ensured to be kept live. 3575 // Frequent allocation and drop of large binary blobs is an 3576 // important use case for eager reclaim, and this special handling 3577 // may reduce needed headroom. 3578 3579 return is_typeArray_region(region) && is_remset_small(region); 3580 } 3581 3582 public: 3583 RegisterHumongousWithInCSetFastTestClosure() 3584 : _total_humongous(0), 3585 _candidate_humongous(0), 3586 _dcq(&JavaThread::dirty_card_queue_set()) { 3587 } 3588 3589 virtual bool doHeapRegion(HeapRegion* r) { 3590 if (!r->is_starts_humongous()) { 3591 return false; 3592 } 3593 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3594 3595 bool is_candidate = humongous_region_is_candidate(g1h, r); 3596 uint rindex = r->hrm_index(); 3597 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 3598 if (is_candidate) { 3599 _candidate_humongous++; 3600 g1h->register_humongous_region_with_cset(rindex); 3601 // Is_candidate already filters out humongous object with large remembered sets. 3602 // If we have a humongous object with a few remembered sets, we simply flush these 3603 // remembered set entries into the DCQS. That will result in automatic 3604 // re-evaluation of their remembered set entries during the following evacuation 3605 // phase. 3606 if (!r->rem_set()->is_empty()) { 3607 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 3608 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 3609 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 3610 HeapRegionRemSetIterator hrrs(r->rem_set()); 3611 size_t card_index; 3612 while (hrrs.has_next(card_index)) { 3613 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 3614 // The remembered set might contain references to already freed 3615 // regions. Filter out such entries to avoid failing card table 3616 // verification. 3617 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) { 3618 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 3619 *card_ptr = CardTableModRefBS::dirty_card_val(); 3620 _dcq.enqueue(card_ptr); 3621 } 3622 } 3623 } 3624 r->rem_set()->clear_locked(); 3625 } 3626 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 3627 } 3628 _total_humongous++; 3629 3630 return false; 3631 } 3632 3633 size_t total_humongous() const { return _total_humongous; } 3634 size_t candidate_humongous() const { return _candidate_humongous; } 3635 3636 void flush_rem_set_entries() { _dcq.flush(); } 3637 }; 3638 3639 void G1CollectedHeap::register_humongous_regions_with_cset() { 3640 if (!G1EagerReclaimHumongousObjects) { 3641 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 3642 return; 3643 } 3644 double time = os::elapsed_counter(); 3645 3646 // Collect reclaim candidate information and register candidates with cset. 3647 RegisterHumongousWithInCSetFastTestClosure cl; 3648 heap_region_iterate(&cl); 3649 3650 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 3651 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 3652 cl.total_humongous(), 3653 cl.candidate_humongous()); 3654 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3655 3656 // Finally flush all remembered set entries to re-check into the global DCQS. 3657 cl.flush_rem_set_entries(); 3658 } 3659 3660 #ifdef ASSERT 3661 class VerifyCSetClosure: public HeapRegionClosure { 3662 public: 3663 bool doHeapRegion(HeapRegion* hr) { 3664 // Here we check that the CSet region's RSet is ready for parallel 3665 // iteration. The fields that we'll verify are only manipulated 3666 // when the region is part of a CSet and is collected. Afterwards, 3667 // we reset these fields when we clear the region's RSet (when the 3668 // region is freed) so they are ready when the region is 3669 // re-allocated. The only exception to this is if there's an 3670 // evacuation failure and instead of freeing the region we leave 3671 // it in the heap. In that case, we reset these fields during 3672 // evacuation failure handling. 3673 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3674 3675 // Here's a good place to add any other checks we'd like to 3676 // perform on CSet regions. 3677 return false; 3678 } 3679 }; 3680 #endif // ASSERT 3681 3682 uint G1CollectedHeap::num_task_queues() const { 3683 return _task_queues->size(); 3684 } 3685 3686 #if TASKQUEUE_STATS 3687 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3688 st->print_raw_cr("GC Task Stats"); 3689 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3690 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3691 } 3692 3693 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3694 print_taskqueue_stats_hdr(st); 3695 3696 TaskQueueStats totals; 3697 const uint n = num_task_queues(); 3698 for (uint i = 0; i < n; ++i) { 3699 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 3700 totals += task_queue(i)->stats; 3701 } 3702 st->print_raw("tot "); totals.print(st); st->cr(); 3703 3704 DEBUG_ONLY(totals.verify()); 3705 } 3706 3707 void G1CollectedHeap::reset_taskqueue_stats() { 3708 const uint n = num_task_queues(); 3709 for (uint i = 0; i < n; ++i) { 3710 task_queue(i)->stats.reset(); 3711 } 3712 } 3713 #endif // TASKQUEUE_STATS 3714 3715 void G1CollectedHeap::log_gc_header() { 3716 if (!G1Log::fine()) { 3717 return; 3718 } 3719 3720 gclog_or_tty->gclog_stamp(); 3721 3722 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3723 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)") 3724 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3725 3726 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3727 } 3728 3729 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3730 if (!G1Log::fine()) { 3731 return; 3732 } 3733 3734 if (G1Log::finer()) { 3735 if (evacuation_failed()) { 3736 gclog_or_tty->print(" (to-space exhausted)"); 3737 } 3738 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3739 g1_policy()->print_phases(pause_time_sec); 3740 g1_policy()->print_detailed_heap_transition(); 3741 } else { 3742 if (evacuation_failed()) { 3743 gclog_or_tty->print("--"); 3744 } 3745 g1_policy()->print_heap_transition(); 3746 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3747 } 3748 gclog_or_tty->flush(); 3749 } 3750 3751 void G1CollectedHeap::wait_for_root_region_scanning() { 3752 double scan_wait_start = os::elapsedTime(); 3753 // We have to wait until the CM threads finish scanning the 3754 // root regions as it's the only way to ensure that all the 3755 // objects on them have been correctly scanned before we start 3756 // moving them during the GC. 3757 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3758 double wait_time_ms = 0.0; 3759 if (waited) { 3760 double scan_wait_end = os::elapsedTime(); 3761 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3762 } 3763 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3764 } 3765 3766 bool 3767 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3768 assert_at_safepoint(true /* should_be_vm_thread */); 3769 guarantee(!is_gc_active(), "collection is not reentrant"); 3770 3771 if (GC_locker::check_active_before_gc()) { 3772 return false; 3773 } 3774 3775 _gc_timer_stw->register_gc_start(); 3776 3777 GCIdMark gc_id_mark; 3778 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3779 3780 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3781 ResourceMark rm; 3782 3783 wait_for_root_region_scanning(); 3784 3785 G1Log::update_level(); 3786 print_heap_before_gc(); 3787 trace_heap_before_gc(_gc_tracer_stw); 3788 3789 verify_region_sets_optional(); 3790 verify_dirty_young_regions(); 3791 3792 // This call will decide whether this pause is an initial-mark 3793 // pause. If it is, during_initial_mark_pause() will return true 3794 // for the duration of this pause. 3795 g1_policy()->decide_on_conc_mark_initiation(); 3796 3797 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3798 assert(!collector_state()->during_initial_mark_pause() || 3799 collector_state()->gcs_are_young(), "sanity"); 3800 3801 // We also do not allow mixed GCs during marking. 3802 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity"); 3803 3804 // Record whether this pause is an initial mark. When the current 3805 // thread has completed its logging output and it's safe to signal 3806 // the CM thread, the flag's value in the policy has been reset. 3807 bool should_start_conc_mark = collector_state()->during_initial_mark_pause(); 3808 3809 // Inner scope for scope based logging, timers, and stats collection 3810 { 3811 EvacuationInfo evacuation_info; 3812 3813 if (collector_state()->during_initial_mark_pause()) { 3814 // We are about to start a marking cycle, so we increment the 3815 // full collection counter. 3816 increment_old_marking_cycles_started(); 3817 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3818 } 3819 3820 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 3821 3822 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3823 3824 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 3825 workers()->active_workers(), 3826 Threads::number_of_non_daemon_threads()); 3827 workers()->set_active_workers(active_workers); 3828 3829 double pause_start_sec = os::elapsedTime(); 3830 g1_policy()->note_gc_start(active_workers); 3831 log_gc_header(); 3832 3833 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3834 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3835 3836 // If the secondary_free_list is not empty, append it to the 3837 // free_list. No need to wait for the cleanup operation to finish; 3838 // the region allocation code will check the secondary_free_list 3839 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3840 // set, skip this step so that the region allocation code has to 3841 // get entries from the secondary_free_list. 3842 if (!G1StressConcRegionFreeing) { 3843 append_secondary_free_list_if_not_empty_with_lock(); 3844 } 3845 3846 assert(check_young_list_well_formed(), "young list should be well formed"); 3847 3848 // Don't dynamically change the number of GC threads this early. A value of 3849 // 0 is used to indicate serial work. When parallel work is done, 3850 // it will be set. 3851 3852 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3853 IsGCActiveMark x; 3854 3855 gc_prologue(false); 3856 increment_total_collections(false /* full gc */); 3857 increment_gc_time_stamp(); 3858 3859 verify_before_gc(); 3860 3861 check_bitmaps("GC Start"); 3862 3863 #if defined(COMPILER2) || INCLUDE_JVMCI 3864 DerivedPointerTable::clear(); 3865 #endif 3866 3867 // Please see comment in g1CollectedHeap.hpp and 3868 // G1CollectedHeap::ref_processing_init() to see how 3869 // reference processing currently works in G1. 3870 3871 // Enable discovery in the STW reference processor 3872 ref_processor_stw()->enable_discovery(); 3873 3874 { 3875 // We want to temporarily turn off discovery by the 3876 // CM ref processor, if necessary, and turn it back on 3877 // on again later if we do. Using a scoped 3878 // NoRefDiscovery object will do this. 3879 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3880 3881 // Forget the current alloc region (we might even choose it to be part 3882 // of the collection set!). 3883 _allocator->release_mutator_alloc_region(); 3884 3885 // We should call this after we retire the mutator alloc 3886 // region(s) so that all the ALLOC / RETIRE events are generated 3887 // before the start GC event. 3888 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3889 3890 // This timing is only used by the ergonomics to handle our pause target. 3891 // It is unclear why this should not include the full pause. We will 3892 // investigate this in CR 7178365. 3893 // 3894 // Preserving the old comment here if that helps the investigation: 3895 // 3896 // The elapsed time induced by the start time below deliberately elides 3897 // the possible verification above. 3898 double sample_start_time_sec = os::elapsedTime(); 3899 3900 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3901 3902 if (collector_state()->during_initial_mark_pause()) { 3903 concurrent_mark()->checkpointRootsInitialPre(); 3904 } 3905 3906 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms); 3907 g1_policy()->finalize_old_cset_part(time_remaining_ms); 3908 3909 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length()); 3910 3911 register_humongous_regions_with_cset(); 3912 3913 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3914 3915 _cm->note_start_of_gc(); 3916 // We call this after finalize_cset() to 3917 // ensure that the CSet has been finalized. 3918 _cm->verify_no_cset_oops(); 3919 3920 if (_hr_printer.is_active()) { 3921 HeapRegion* hr = g1_policy()->collection_set(); 3922 while (hr != NULL) { 3923 _hr_printer.cset(hr); 3924 hr = hr->next_in_collection_set(); 3925 } 3926 } 3927 3928 #ifdef ASSERT 3929 VerifyCSetClosure cl; 3930 collection_set_iterate(&cl); 3931 #endif // ASSERT 3932 3933 // Initialize the GC alloc regions. 3934 _allocator->init_gc_alloc_regions(evacuation_info); 3935 3936 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length()); 3937 pre_evacuate_collection_set(); 3938 3939 // Actually do the work... 3940 evacuate_collection_set(evacuation_info, &per_thread_states); 3941 3942 post_evacuate_collection_set(evacuation_info, &per_thread_states); 3943 3944 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 3945 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words); 3946 3947 eagerly_reclaim_humongous_regions(); 3948 3949 g1_policy()->clear_collection_set(); 3950 3951 // Start a new incremental collection set for the next pause. 3952 g1_policy()->start_incremental_cset_building(); 3953 3954 clear_cset_fast_test(); 3955 3956 _young_list->reset_sampled_info(); 3957 3958 // Don't check the whole heap at this point as the 3959 // GC alloc regions from this pause have been tagged 3960 // as survivors and moved on to the survivor list. 3961 // Survivor regions will fail the !is_young() check. 3962 assert(check_young_list_empty(false /* check_heap */), 3963 "young list should be empty"); 3964 3965 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 3966 _young_list->first_survivor_region(), 3967 _young_list->last_survivor_region()); 3968 3969 _young_list->reset_auxilary_lists(); 3970 3971 if (evacuation_failed()) { 3972 set_used(recalculate_used()); 3973 if (_archive_allocator != NULL) { 3974 _archive_allocator->clear_used(); 3975 } 3976 for (uint i = 0; i < ParallelGCThreads; i++) { 3977 if (_evacuation_failed_info_array[i].has_failed()) { 3978 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3979 } 3980 } 3981 } else { 3982 // The "used" of the the collection set have already been subtracted 3983 // when they were freed. Add in the bytes evacuated. 3984 increase_used(g1_policy()->bytes_copied_during_gc()); 3985 } 3986 3987 if (collector_state()->during_initial_mark_pause()) { 3988 // We have to do this before we notify the CM threads that 3989 // they can start working to make sure that all the 3990 // appropriate initialization is done on the CM object. 3991 concurrent_mark()->checkpointRootsInitialPost(); 3992 collector_state()->set_mark_in_progress(true); 3993 // Note that we don't actually trigger the CM thread at 3994 // this point. We do that later when we're sure that 3995 // the current thread has completed its logging output. 3996 } 3997 3998 allocate_dummy_regions(); 3999 4000 _allocator->init_mutator_alloc_region(); 4001 4002 { 4003 size_t expand_bytes = g1_policy()->expansion_amount(); 4004 if (expand_bytes > 0) { 4005 size_t bytes_before = capacity(); 4006 // No need for an ergo verbose message here, 4007 // expansion_amount() does this when it returns a value > 0. 4008 double expand_ms; 4009 if (!expand(expand_bytes, &expand_ms)) { 4010 // We failed to expand the heap. Cannot do anything about it. 4011 } 4012 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 4013 } 4014 } 4015 4016 // We redo the verification but now wrt to the new CSet which 4017 // has just got initialized after the previous CSet was freed. 4018 _cm->verify_no_cset_oops(); 4019 _cm->note_end_of_gc(); 4020 4021 // This timing is only used by the ergonomics to handle our pause target. 4022 // It is unclear why this should not include the full pause. We will 4023 // investigate this in CR 7178365. 4024 double sample_end_time_sec = os::elapsedTime(); 4025 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 4026 size_t total_cards_scanned = per_thread_states.total_cards_scanned(); 4027 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned); 4028 4029 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before()); 4030 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 4031 4032 MemoryService::track_memory_usage(); 4033 4034 // In prepare_for_verify() below we'll need to scan the deferred 4035 // update buffers to bring the RSets up-to-date if 4036 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4037 // the update buffers we'll probably need to scan cards on the 4038 // regions we just allocated to (i.e., the GC alloc 4039 // regions). However, during the last GC we called 4040 // set_saved_mark() on all the GC alloc regions, so card 4041 // scanning might skip the [saved_mark_word()...top()] area of 4042 // those regions (i.e., the area we allocated objects into 4043 // during the last GC). But it shouldn't. Given that 4044 // saved_mark_word() is conditional on whether the GC time stamp 4045 // on the region is current or not, by incrementing the GC time 4046 // stamp here we invalidate all the GC time stamps on all the 4047 // regions and saved_mark_word() will simply return top() for 4048 // all the regions. This is a nicer way of ensuring this rather 4049 // than iterating over the regions and fixing them. In fact, the 4050 // GC time stamp increment here also ensures that 4051 // saved_mark_word() will return top() between pauses, i.e., 4052 // during concurrent refinement. So we don't need the 4053 // is_gc_active() check to decided which top to use when 4054 // scanning cards (see CR 7039627). 4055 increment_gc_time_stamp(); 4056 4057 verify_after_gc(); 4058 check_bitmaps("GC End"); 4059 4060 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4061 ref_processor_stw()->verify_no_references_recorded(); 4062 4063 // CM reference discovery will be re-enabled if necessary. 4064 } 4065 4066 // We should do this after we potentially expand the heap so 4067 // that all the COMMIT events are generated before the end GC 4068 // event, and after we retire the GC alloc regions so that all 4069 // RETIRE events are generated before the end GC event. 4070 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4071 4072 #ifdef TRACESPINNING 4073 ParallelTaskTerminator::print_termination_counts(); 4074 #endif 4075 4076 gc_epilogue(false); 4077 } 4078 4079 // Print the remainder of the GC log output. 4080 log_gc_footer(os::elapsedTime() - pause_start_sec); 4081 4082 // It is not yet to safe to tell the concurrent mark to 4083 // start as we have some optional output below. We don't want the 4084 // output from the concurrent mark thread interfering with this 4085 // logging output either. 4086 4087 _hrm.verify_optional(); 4088 verify_region_sets_optional(); 4089 4090 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats()); 4091 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4092 4093 print_heap_after_gc(); 4094 trace_heap_after_gc(_gc_tracer_stw); 4095 4096 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4097 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4098 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4099 // before any GC notifications are raised. 4100 g1mm()->update_sizes(); 4101 4102 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4103 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4104 _gc_timer_stw->register_gc_end(); 4105 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4106 } 4107 // It should now be safe to tell the concurrent mark thread to start 4108 // without its logging output interfering with the logging output 4109 // that came from the pause. 4110 4111 if (should_start_conc_mark) { 4112 // CAUTION: after the doConcurrentMark() call below, 4113 // the concurrent marking thread(s) could be running 4114 // concurrently with us. Make sure that anything after 4115 // this point does not assume that we are the only GC thread 4116 // running. Note: of course, the actual marking work will 4117 // not start until the safepoint itself is released in 4118 // SuspendibleThreadSet::desynchronize(). 4119 doConcurrentMark(); 4120 } 4121 4122 return true; 4123 } 4124 4125 void G1CollectedHeap::remove_self_forwarding_pointers() { 4126 double remove_self_forwards_start = os::elapsedTime(); 4127 4128 G1ParRemoveSelfForwardPtrsTask rsfp_task; 4129 workers()->run_task(&rsfp_task); 4130 4131 // Now restore saved marks, if any. 4132 for (uint i = 0; i < ParallelGCThreads; i++) { 4133 OopAndMarkOopStack& cur = _preserved_objs[i]; 4134 while (!cur.is_empty()) { 4135 OopAndMarkOop elem = cur.pop(); 4136 elem.set_mark(); 4137 } 4138 cur.clear(true); 4139 } 4140 4141 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4142 } 4143 4144 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 4145 if (!_evacuation_failed) { 4146 _evacuation_failed = true; 4147 } 4148 4149 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 4150 4151 // We want to call the "for_promotion_failure" version only in the 4152 // case of a promotion failure. 4153 if (m->must_be_preserved_for_promotion_failure(obj)) { 4154 OopAndMarkOop elem(obj, m); 4155 _preserved_objs[worker_id].push(elem); 4156 } 4157 } 4158 4159 class G1ParEvacuateFollowersClosure : public VoidClosure { 4160 private: 4161 double _start_term; 4162 double _term_time; 4163 size_t _term_attempts; 4164 4165 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 4166 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 4167 protected: 4168 G1CollectedHeap* _g1h; 4169 G1ParScanThreadState* _par_scan_state; 4170 RefToScanQueueSet* _queues; 4171 ParallelTaskTerminator* _terminator; 4172 4173 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4174 RefToScanQueueSet* queues() { return _queues; } 4175 ParallelTaskTerminator* terminator() { return _terminator; } 4176 4177 public: 4178 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4179 G1ParScanThreadState* par_scan_state, 4180 RefToScanQueueSet* queues, 4181 ParallelTaskTerminator* terminator) 4182 : _g1h(g1h), _par_scan_state(par_scan_state), 4183 _queues(queues), _terminator(terminator), 4184 _start_term(0.0), _term_time(0.0), _term_attempts(0) {} 4185 4186 void do_void(); 4187 4188 double term_time() const { return _term_time; } 4189 size_t term_attempts() const { return _term_attempts; } 4190 4191 private: 4192 inline bool offer_termination(); 4193 }; 4194 4195 bool G1ParEvacuateFollowersClosure::offer_termination() { 4196 G1ParScanThreadState* const pss = par_scan_state(); 4197 start_term_time(); 4198 const bool res = terminator()->offer_termination(); 4199 end_term_time(); 4200 return res; 4201 } 4202 4203 void G1ParEvacuateFollowersClosure::do_void() { 4204 G1ParScanThreadState* const pss = par_scan_state(); 4205 pss->trim_queue(); 4206 do { 4207 pss->steal_and_trim_queue(queues()); 4208 } while (!offer_termination()); 4209 } 4210 4211 class G1ParTask : public AbstractGangTask { 4212 protected: 4213 G1CollectedHeap* _g1h; 4214 G1ParScanThreadStateSet* _pss; 4215 RefToScanQueueSet* _queues; 4216 G1RootProcessor* _root_processor; 4217 ParallelTaskTerminator _terminator; 4218 uint _n_workers; 4219 4220 public: 4221 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 4222 : AbstractGangTask("G1 collection"), 4223 _g1h(g1h), 4224 _pss(per_thread_states), 4225 _queues(task_queues), 4226 _root_processor(root_processor), 4227 _terminator(n_workers, _queues), 4228 _n_workers(n_workers) 4229 {} 4230 4231 void work(uint worker_id) { 4232 if (worker_id >= _n_workers) return; // no work needed this round 4233 4234 double start_sec = os::elapsedTime(); 4235 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 4236 4237 { 4238 ResourceMark rm; 4239 HandleMark hm; 4240 4241 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4242 4243 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4244 pss->set_ref_processor(rp); 4245 4246 double start_strong_roots_sec = os::elapsedTime(); 4247 4248 _root_processor->evacuate_roots(pss->closures(), worker_id); 4249 4250 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss); 4251 4252 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid 4253 // treating the nmethods visited to act as roots for concurrent marking. 4254 // We only want to make sure that the oops in the nmethods are adjusted with regard to the 4255 // objects copied by the current evacuation. 4256 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl, 4257 pss->closures()->weak_codeblobs(), 4258 worker_id); 4259 4260 _pss->add_cards_scanned(worker_id, cards_scanned); 4261 4262 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 4263 4264 double term_sec = 0.0; 4265 size_t evac_term_attempts = 0; 4266 { 4267 double start = os::elapsedTime(); 4268 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator); 4269 evac.do_void(); 4270 4271 evac_term_attempts = evac.term_attempts(); 4272 term_sec = evac.term_time(); 4273 double elapsed_sec = os::elapsedTime() - start; 4274 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 4275 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 4276 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 4277 } 4278 4279 assert(pss->queue_is_empty(), "should be empty"); 4280 4281 if (PrintTerminationStats) { 4282 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 4283 size_t lab_waste; 4284 size_t lab_undo_waste; 4285 pss->waste(lab_waste, lab_undo_waste); 4286 _g1h->print_termination_stats(gclog_or_tty, 4287 worker_id, 4288 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 4289 strong_roots_sec * 1000.0, /* strong roots time */ 4290 term_sec * 1000.0, /* evac term time */ 4291 evac_term_attempts, /* evac term attempts */ 4292 lab_waste, /* alloc buffer waste */ 4293 lab_undo_waste /* undo waste */ 4294 ); 4295 } 4296 4297 // Close the inner scope so that the ResourceMark and HandleMark 4298 // destructors are executed here and are included as part of the 4299 // "GC Worker Time". 4300 } 4301 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 4302 } 4303 }; 4304 4305 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) { 4306 st->print_raw_cr("GC Termination Stats"); 4307 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 4308 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo"); 4309 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 4310 } 4311 4312 void G1CollectedHeap::print_termination_stats(outputStream* const st, 4313 uint worker_id, 4314 double elapsed_ms, 4315 double strong_roots_ms, 4316 double term_ms, 4317 size_t term_attempts, 4318 size_t alloc_buffer_waste, 4319 size_t undo_waste) const { 4320 st->print_cr("%3d %9.2f %9.2f %6.2f " 4321 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 4322 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 4323 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 4324 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 4325 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 4326 alloc_buffer_waste * HeapWordSize / K, 4327 undo_waste * HeapWordSize / K); 4328 } 4329 4330 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4331 private: 4332 BoolObjectClosure* _is_alive; 4333 int _initial_string_table_size; 4334 int _initial_symbol_table_size; 4335 4336 bool _process_strings; 4337 int _strings_processed; 4338 int _strings_removed; 4339 4340 bool _process_symbols; 4341 int _symbols_processed; 4342 int _symbols_removed; 4343 4344 public: 4345 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4346 AbstractGangTask("String/Symbol Unlinking"), 4347 _is_alive(is_alive), 4348 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4349 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4350 4351 _initial_string_table_size = StringTable::the_table()->table_size(); 4352 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4353 if (process_strings) { 4354 StringTable::clear_parallel_claimed_index(); 4355 } 4356 if (process_symbols) { 4357 SymbolTable::clear_parallel_claimed_index(); 4358 } 4359 } 4360 4361 ~G1StringSymbolTableUnlinkTask() { 4362 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4363 "claim value %d after unlink less than initial string table size %d", 4364 StringTable::parallel_claimed_index(), _initial_string_table_size); 4365 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4366 "claim value %d after unlink less than initial symbol table size %d", 4367 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size); 4368 4369 if (G1TraceStringSymbolTableScrubbing) { 4370 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4371 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, " 4372 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed", 4373 strings_processed(), strings_removed(), 4374 symbols_processed(), symbols_removed()); 4375 } 4376 } 4377 4378 void work(uint worker_id) { 4379 int strings_processed = 0; 4380 int strings_removed = 0; 4381 int symbols_processed = 0; 4382 int symbols_removed = 0; 4383 if (_process_strings) { 4384 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4385 Atomic::add(strings_processed, &_strings_processed); 4386 Atomic::add(strings_removed, &_strings_removed); 4387 } 4388 if (_process_symbols) { 4389 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 4390 Atomic::add(symbols_processed, &_symbols_processed); 4391 Atomic::add(symbols_removed, &_symbols_removed); 4392 } 4393 } 4394 4395 size_t strings_processed() const { return (size_t)_strings_processed; } 4396 size_t strings_removed() const { return (size_t)_strings_removed; } 4397 4398 size_t symbols_processed() const { return (size_t)_symbols_processed; } 4399 size_t symbols_removed() const { return (size_t)_symbols_removed; } 4400 }; 4401 4402 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 4403 private: 4404 static Monitor* _lock; 4405 4406 BoolObjectClosure* const _is_alive; 4407 const bool _unloading_occurred; 4408 const uint _num_workers; 4409 4410 // Variables used to claim nmethods. 4411 nmethod* _first_nmethod; 4412 volatile nmethod* _claimed_nmethod; 4413 4414 // The list of nmethods that need to be processed by the second pass. 4415 volatile nmethod* _postponed_list; 4416 volatile uint _num_entered_barrier; 4417 4418 public: 4419 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 4420 _is_alive(is_alive), 4421 _unloading_occurred(unloading_occurred), 4422 _num_workers(num_workers), 4423 _first_nmethod(NULL), 4424 _claimed_nmethod(NULL), 4425 _postponed_list(NULL), 4426 _num_entered_barrier(0) 4427 { 4428 nmethod::increase_unloading_clock(); 4429 // Get first alive nmethod 4430 NMethodIterator iter = NMethodIterator(); 4431 if(iter.next_alive()) { 4432 _first_nmethod = iter.method(); 4433 } 4434 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 4435 } 4436 4437 ~G1CodeCacheUnloadingTask() { 4438 CodeCache::verify_clean_inline_caches(); 4439 4440 CodeCache::set_needs_cache_clean(false); 4441 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 4442 4443 CodeCache::verify_icholder_relocations(); 4444 } 4445 4446 private: 4447 void add_to_postponed_list(nmethod* nm) { 4448 nmethod* old; 4449 do { 4450 old = (nmethod*)_postponed_list; 4451 nm->set_unloading_next(old); 4452 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 4453 } 4454 4455 void clean_nmethod(nmethod* nm) { 4456 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 4457 4458 if (postponed) { 4459 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 4460 add_to_postponed_list(nm); 4461 } 4462 4463 // Mark that this thread has been cleaned/unloaded. 4464 // After this call, it will be safe to ask if this nmethod was unloaded or not. 4465 nm->set_unloading_clock(nmethod::global_unloading_clock()); 4466 } 4467 4468 void clean_nmethod_postponed(nmethod* nm) { 4469 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 4470 } 4471 4472 static const int MaxClaimNmethods = 16; 4473 4474 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 4475 nmethod* first; 4476 NMethodIterator last; 4477 4478 do { 4479 *num_claimed_nmethods = 0; 4480 4481 first = (nmethod*)_claimed_nmethod; 4482 last = NMethodIterator(first); 4483 4484 if (first != NULL) { 4485 4486 for (int i = 0; i < MaxClaimNmethods; i++) { 4487 if (!last.next_alive()) { 4488 break; 4489 } 4490 claimed_nmethods[i] = last.method(); 4491 (*num_claimed_nmethods)++; 4492 } 4493 } 4494 4495 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 4496 } 4497 4498 nmethod* claim_postponed_nmethod() { 4499 nmethod* claim; 4500 nmethod* next; 4501 4502 do { 4503 claim = (nmethod*)_postponed_list; 4504 if (claim == NULL) { 4505 return NULL; 4506 } 4507 4508 next = claim->unloading_next(); 4509 4510 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 4511 4512 return claim; 4513 } 4514 4515 public: 4516 // Mark that we're done with the first pass of nmethod cleaning. 4517 void barrier_mark(uint worker_id) { 4518 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4519 _num_entered_barrier++; 4520 if (_num_entered_barrier == _num_workers) { 4521 ml.notify_all(); 4522 } 4523 } 4524 4525 // See if we have to wait for the other workers to 4526 // finish their first-pass nmethod cleaning work. 4527 void barrier_wait(uint worker_id) { 4528 if (_num_entered_barrier < _num_workers) { 4529 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4530 while (_num_entered_barrier < _num_workers) { 4531 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 4532 } 4533 } 4534 } 4535 4536 // Cleaning and unloading of nmethods. Some work has to be postponed 4537 // to the second pass, when we know which nmethods survive. 4538 void work_first_pass(uint worker_id) { 4539 // The first nmethods is claimed by the first worker. 4540 if (worker_id == 0 && _first_nmethod != NULL) { 4541 clean_nmethod(_first_nmethod); 4542 _first_nmethod = NULL; 4543 } 4544 4545 int num_claimed_nmethods; 4546 nmethod* claimed_nmethods[MaxClaimNmethods]; 4547 4548 while (true) { 4549 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 4550 4551 if (num_claimed_nmethods == 0) { 4552 break; 4553 } 4554 4555 for (int i = 0; i < num_claimed_nmethods; i++) { 4556 clean_nmethod(claimed_nmethods[i]); 4557 } 4558 } 4559 } 4560 4561 void work_second_pass(uint worker_id) { 4562 nmethod* nm; 4563 // Take care of postponed nmethods. 4564 while ((nm = claim_postponed_nmethod()) != NULL) { 4565 clean_nmethod_postponed(nm); 4566 } 4567 } 4568 }; 4569 4570 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 4571 4572 class G1KlassCleaningTask : public StackObj { 4573 BoolObjectClosure* _is_alive; 4574 volatile jint _clean_klass_tree_claimed; 4575 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 4576 4577 public: 4578 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 4579 _is_alive(is_alive), 4580 _clean_klass_tree_claimed(0), 4581 _klass_iterator() { 4582 } 4583 4584 private: 4585 bool claim_clean_klass_tree_task() { 4586 if (_clean_klass_tree_claimed) { 4587 return false; 4588 } 4589 4590 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 4591 } 4592 4593 InstanceKlass* claim_next_klass() { 4594 Klass* klass; 4595 do { 4596 klass =_klass_iterator.next_klass(); 4597 } while (klass != NULL && !klass->is_instance_klass()); 4598 4599 // this can be null so don't call InstanceKlass::cast 4600 return static_cast<InstanceKlass*>(klass); 4601 } 4602 4603 public: 4604 4605 void clean_klass(InstanceKlass* ik) { 4606 ik->clean_weak_instanceklass_links(_is_alive); 4607 } 4608 4609 void work() { 4610 ResourceMark rm; 4611 4612 // One worker will clean the subklass/sibling klass tree. 4613 if (claim_clean_klass_tree_task()) { 4614 Klass::clean_subklass_tree(_is_alive); 4615 } 4616 4617 // All workers will help cleaning the classes, 4618 InstanceKlass* klass; 4619 while ((klass = claim_next_klass()) != NULL) { 4620 clean_klass(klass); 4621 } 4622 } 4623 }; 4624 4625 // To minimize the remark pause times, the tasks below are done in parallel. 4626 class G1ParallelCleaningTask : public AbstractGangTask { 4627 private: 4628 G1StringSymbolTableUnlinkTask _string_symbol_task; 4629 G1CodeCacheUnloadingTask _code_cache_task; 4630 G1KlassCleaningTask _klass_cleaning_task; 4631 4632 public: 4633 // The constructor is run in the VMThread. 4634 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 4635 AbstractGangTask("Parallel Cleaning"), 4636 _string_symbol_task(is_alive, process_strings, process_symbols), 4637 _code_cache_task(num_workers, is_alive, unloading_occurred), 4638 _klass_cleaning_task(is_alive) { 4639 } 4640 4641 // The parallel work done by all worker threads. 4642 void work(uint worker_id) { 4643 // Do first pass of code cache cleaning. 4644 _code_cache_task.work_first_pass(worker_id); 4645 4646 // Let the threads mark that the first pass is done. 4647 _code_cache_task.barrier_mark(worker_id); 4648 4649 // Clean the Strings and Symbols. 4650 _string_symbol_task.work(worker_id); 4651 4652 // Wait for all workers to finish the first code cache cleaning pass. 4653 _code_cache_task.barrier_wait(worker_id); 4654 4655 // Do the second code cache cleaning work, which realize on 4656 // the liveness information gathered during the first pass. 4657 _code_cache_task.work_second_pass(worker_id); 4658 4659 // Clean all klasses that were not unloaded. 4660 _klass_cleaning_task.work(); 4661 } 4662 }; 4663 4664 4665 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 4666 bool process_strings, 4667 bool process_symbols, 4668 bool class_unloading_occurred) { 4669 uint n_workers = workers()->active_workers(); 4670 4671 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 4672 n_workers, class_unloading_occurred); 4673 workers()->run_task(&g1_unlink_task); 4674 } 4675 4676 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 4677 bool process_strings, bool process_symbols) { 4678 { 4679 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 4680 workers()->run_task(&g1_unlink_task); 4681 } 4682 4683 if (G1StringDedup::is_enabled()) { 4684 G1StringDedup::unlink(is_alive); 4685 } 4686 } 4687 4688 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 4689 private: 4690 DirtyCardQueueSet* _queue; 4691 public: 4692 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 4693 4694 virtual void work(uint worker_id) { 4695 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4696 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 4697 4698 RedirtyLoggedCardTableEntryClosure cl; 4699 _queue->par_apply_closure_to_all_completed_buffers(&cl); 4700 4701 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed()); 4702 } 4703 }; 4704 4705 void G1CollectedHeap::redirty_logged_cards() { 4706 double redirty_logged_cards_start = os::elapsedTime(); 4707 4708 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 4709 dirty_card_queue_set().reset_for_par_iteration(); 4710 workers()->run_task(&redirty_task); 4711 4712 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 4713 dcq.merge_bufferlists(&dirty_card_queue_set()); 4714 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 4715 4716 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 4717 } 4718 4719 // Weak Reference Processing support 4720 4721 // An always "is_alive" closure that is used to preserve referents. 4722 // If the object is non-null then it's alive. Used in the preservation 4723 // of referent objects that are pointed to by reference objects 4724 // discovered by the CM ref processor. 4725 class G1AlwaysAliveClosure: public BoolObjectClosure { 4726 G1CollectedHeap* _g1; 4727 public: 4728 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4729 bool do_object_b(oop p) { 4730 if (p != NULL) { 4731 return true; 4732 } 4733 return false; 4734 } 4735 }; 4736 4737 bool G1STWIsAliveClosure::do_object_b(oop p) { 4738 // An object is reachable if it is outside the collection set, 4739 // or is inside and copied. 4740 return !_g1->is_in_cset(p) || p->is_forwarded(); 4741 } 4742 4743 // Non Copying Keep Alive closure 4744 class G1KeepAliveClosure: public OopClosure { 4745 G1CollectedHeap* _g1; 4746 public: 4747 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4748 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 4749 void do_oop(oop* p) { 4750 oop obj = *p; 4751 assert(obj != NULL, "the caller should have filtered out NULL values"); 4752 4753 const InCSetState cset_state = _g1->in_cset_state(obj); 4754 if (!cset_state.is_in_cset_or_humongous()) { 4755 return; 4756 } 4757 if (cset_state.is_in_cset()) { 4758 assert( obj->is_forwarded(), "invariant" ); 4759 *p = obj->forwardee(); 4760 } else { 4761 assert(!obj->is_forwarded(), "invariant" ); 4762 assert(cset_state.is_humongous(), 4763 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 4764 _g1->set_humongous_is_live(obj); 4765 } 4766 } 4767 }; 4768 4769 // Copying Keep Alive closure - can be called from both 4770 // serial and parallel code as long as different worker 4771 // threads utilize different G1ParScanThreadState instances 4772 // and different queues. 4773 4774 class G1CopyingKeepAliveClosure: public OopClosure { 4775 G1CollectedHeap* _g1h; 4776 OopClosure* _copy_non_heap_obj_cl; 4777 G1ParScanThreadState* _par_scan_state; 4778 4779 public: 4780 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 4781 OopClosure* non_heap_obj_cl, 4782 G1ParScanThreadState* pss): 4783 _g1h(g1h), 4784 _copy_non_heap_obj_cl(non_heap_obj_cl), 4785 _par_scan_state(pss) 4786 {} 4787 4788 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 4789 virtual void do_oop( oop* p) { do_oop_work(p); } 4790 4791 template <class T> void do_oop_work(T* p) { 4792 oop obj = oopDesc::load_decode_heap_oop(p); 4793 4794 if (_g1h->is_in_cset_or_humongous(obj)) { 4795 // If the referent object has been forwarded (either copied 4796 // to a new location or to itself in the event of an 4797 // evacuation failure) then we need to update the reference 4798 // field and, if both reference and referent are in the G1 4799 // heap, update the RSet for the referent. 4800 // 4801 // If the referent has not been forwarded then we have to keep 4802 // it alive by policy. Therefore we have copy the referent. 4803 // 4804 // If the reference field is in the G1 heap then we can push 4805 // on the PSS queue. When the queue is drained (after each 4806 // phase of reference processing) the object and it's followers 4807 // will be copied, the reference field set to point to the 4808 // new location, and the RSet updated. Otherwise we need to 4809 // use the the non-heap or metadata closures directly to copy 4810 // the referent object and update the pointer, while avoiding 4811 // updating the RSet. 4812 4813 if (_g1h->is_in_g1_reserved(p)) { 4814 _par_scan_state->push_on_queue(p); 4815 } else { 4816 assert(!Metaspace::contains((const void*)p), 4817 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)); 4818 _copy_non_heap_obj_cl->do_oop(p); 4819 } 4820 } 4821 } 4822 }; 4823 4824 // Serial drain queue closure. Called as the 'complete_gc' 4825 // closure for each discovered list in some of the 4826 // reference processing phases. 4827 4828 class G1STWDrainQueueClosure: public VoidClosure { 4829 protected: 4830 G1CollectedHeap* _g1h; 4831 G1ParScanThreadState* _par_scan_state; 4832 4833 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4834 4835 public: 4836 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 4837 _g1h(g1h), 4838 _par_scan_state(pss) 4839 { } 4840 4841 void do_void() { 4842 G1ParScanThreadState* const pss = par_scan_state(); 4843 pss->trim_queue(); 4844 } 4845 }; 4846 4847 // Parallel Reference Processing closures 4848 4849 // Implementation of AbstractRefProcTaskExecutor for parallel reference 4850 // processing during G1 evacuation pauses. 4851 4852 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 4853 private: 4854 G1CollectedHeap* _g1h; 4855 G1ParScanThreadStateSet* _pss; 4856 RefToScanQueueSet* _queues; 4857 WorkGang* _workers; 4858 uint _active_workers; 4859 4860 public: 4861 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 4862 G1ParScanThreadStateSet* per_thread_states, 4863 WorkGang* workers, 4864 RefToScanQueueSet *task_queues, 4865 uint n_workers) : 4866 _g1h(g1h), 4867 _pss(per_thread_states), 4868 _queues(task_queues), 4869 _workers(workers), 4870 _active_workers(n_workers) 4871 { 4872 assert(n_workers > 0, "shouldn't call this otherwise"); 4873 } 4874 4875 // Executes the given task using concurrent marking worker threads. 4876 virtual void execute(ProcessTask& task); 4877 virtual void execute(EnqueueTask& task); 4878 }; 4879 4880 // Gang task for possibly parallel reference processing 4881 4882 class G1STWRefProcTaskProxy: public AbstractGangTask { 4883 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 4884 ProcessTask& _proc_task; 4885 G1CollectedHeap* _g1h; 4886 G1ParScanThreadStateSet* _pss; 4887 RefToScanQueueSet* _task_queues; 4888 ParallelTaskTerminator* _terminator; 4889 4890 public: 4891 G1STWRefProcTaskProxy(ProcessTask& proc_task, 4892 G1CollectedHeap* g1h, 4893 G1ParScanThreadStateSet* per_thread_states, 4894 RefToScanQueueSet *task_queues, 4895 ParallelTaskTerminator* terminator) : 4896 AbstractGangTask("Process reference objects in parallel"), 4897 _proc_task(proc_task), 4898 _g1h(g1h), 4899 _pss(per_thread_states), 4900 _task_queues(task_queues), 4901 _terminator(terminator) 4902 {} 4903 4904 virtual void work(uint worker_id) { 4905 // The reference processing task executed by a single worker. 4906 ResourceMark rm; 4907 HandleMark hm; 4908 4909 G1STWIsAliveClosure is_alive(_g1h); 4910 4911 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4912 pss->set_ref_processor(NULL); 4913 4914 // Keep alive closure. 4915 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 4916 4917 // Complete GC closure 4918 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator); 4919 4920 // Call the reference processing task's work routine. 4921 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 4922 4923 // Note we cannot assert that the refs array is empty here as not all 4924 // of the processing tasks (specifically phase2 - pp2_work) execute 4925 // the complete_gc closure (which ordinarily would drain the queue) so 4926 // the queue may not be empty. 4927 } 4928 }; 4929 4930 // Driver routine for parallel reference processing. 4931 // Creates an instance of the ref processing gang 4932 // task and has the worker threads execute it. 4933 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 4934 assert(_workers != NULL, "Need parallel worker threads."); 4935 4936 ParallelTaskTerminator terminator(_active_workers, _queues); 4937 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 4938 4939 _workers->run_task(&proc_task_proxy); 4940 } 4941 4942 // Gang task for parallel reference enqueueing. 4943 4944 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 4945 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 4946 EnqueueTask& _enq_task; 4947 4948 public: 4949 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 4950 AbstractGangTask("Enqueue reference objects in parallel"), 4951 _enq_task(enq_task) 4952 { } 4953 4954 virtual void work(uint worker_id) { 4955 _enq_task.work(worker_id); 4956 } 4957 }; 4958 4959 // Driver routine for parallel reference enqueueing. 4960 // Creates an instance of the ref enqueueing gang 4961 // task and has the worker threads execute it. 4962 4963 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 4964 assert(_workers != NULL, "Need parallel worker threads."); 4965 4966 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 4967 4968 _workers->run_task(&enq_task_proxy); 4969 } 4970 4971 // End of weak reference support closures 4972 4973 // Abstract task used to preserve (i.e. copy) any referent objects 4974 // that are in the collection set and are pointed to by reference 4975 // objects discovered by the CM ref processor. 4976 4977 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 4978 protected: 4979 G1CollectedHeap* _g1h; 4980 G1ParScanThreadStateSet* _pss; 4981 RefToScanQueueSet* _queues; 4982 ParallelTaskTerminator _terminator; 4983 uint _n_workers; 4984 4985 public: 4986 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) : 4987 AbstractGangTask("ParPreserveCMReferents"), 4988 _g1h(g1h), 4989 _pss(per_thread_states), 4990 _queues(task_queues), 4991 _terminator(workers, _queues), 4992 _n_workers(workers) 4993 { } 4994 4995 void work(uint worker_id) { 4996 ResourceMark rm; 4997 HandleMark hm; 4998 4999 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 5000 pss->set_ref_processor(NULL); 5001 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 5002 5003 // Is alive closure 5004 G1AlwaysAliveClosure always_alive(_g1h); 5005 5006 // Copying keep alive closure. Applied to referent objects that need 5007 // to be copied. 5008 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 5009 5010 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5011 5012 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5013 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5014 5015 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5016 // So this must be true - but assert just in case someone decides to 5017 // change the worker ids. 5018 assert(worker_id < limit, "sanity"); 5019 assert(!rp->discovery_is_atomic(), "check this code"); 5020 5021 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5022 for (uint idx = worker_id; idx < limit; idx += stride) { 5023 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5024 5025 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5026 while (iter.has_next()) { 5027 // Since discovery is not atomic for the CM ref processor, we 5028 // can see some null referent objects. 5029 iter.load_ptrs(DEBUG_ONLY(true)); 5030 oop ref = iter.obj(); 5031 5032 // This will filter nulls. 5033 if (iter.is_referent_alive()) { 5034 iter.make_referent_alive(); 5035 } 5036 iter.move_to_next(); 5037 } 5038 } 5039 5040 // Drain the queue - which may cause stealing 5041 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator); 5042 drain_queue.do_void(); 5043 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5044 assert(pss->queue_is_empty(), "should be"); 5045 } 5046 }; 5047 5048 // Weak Reference processing during an evacuation pause (part 1). 5049 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 5050 double ref_proc_start = os::elapsedTime(); 5051 5052 ReferenceProcessor* rp = _ref_processor_stw; 5053 assert(rp->discovery_enabled(), "should have been enabled"); 5054 5055 // Any reference objects, in the collection set, that were 'discovered' 5056 // by the CM ref processor should have already been copied (either by 5057 // applying the external root copy closure to the discovered lists, or 5058 // by following an RSet entry). 5059 // 5060 // But some of the referents, that are in the collection set, that these 5061 // reference objects point to may not have been copied: the STW ref 5062 // processor would have seen that the reference object had already 5063 // been 'discovered' and would have skipped discovering the reference, 5064 // but would not have treated the reference object as a regular oop. 5065 // As a result the copy closure would not have been applied to the 5066 // referent object. 5067 // 5068 // We need to explicitly copy these referent objects - the references 5069 // will be processed at the end of remarking. 5070 // 5071 // We also need to do this copying before we process the reference 5072 // objects discovered by the STW ref processor in case one of these 5073 // referents points to another object which is also referenced by an 5074 // object discovered by the STW ref processor. 5075 5076 uint no_of_gc_workers = workers()->active_workers(); 5077 5078 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5079 per_thread_states, 5080 no_of_gc_workers, 5081 _task_queues); 5082 5083 workers()->run_task(&keep_cm_referents); 5084 5085 // Closure to test whether a referent is alive. 5086 G1STWIsAliveClosure is_alive(this); 5087 5088 // Even when parallel reference processing is enabled, the processing 5089 // of JNI refs is serial and performed serially by the current thread 5090 // rather than by a worker. The following PSS will be used for processing 5091 // JNI refs. 5092 5093 // Use only a single queue for this PSS. 5094 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 5095 pss->set_ref_processor(NULL); 5096 assert(pss->queue_is_empty(), "pre-condition"); 5097 5098 // Keep alive closure. 5099 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss); 5100 5101 // Serial Complete GC closure 5102 G1STWDrainQueueClosure drain_queue(this, pss); 5103 5104 // Setup the soft refs policy... 5105 rp->setup_policy(false); 5106 5107 ReferenceProcessorStats stats; 5108 if (!rp->processing_is_mt()) { 5109 // Serial reference processing... 5110 stats = rp->process_discovered_references(&is_alive, 5111 &keep_alive, 5112 &drain_queue, 5113 NULL, 5114 _gc_timer_stw); 5115 } else { 5116 // Parallel reference processing 5117 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5118 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5119 5120 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers); 5121 stats = rp->process_discovered_references(&is_alive, 5122 &keep_alive, 5123 &drain_queue, 5124 &par_task_executor, 5125 _gc_timer_stw); 5126 } 5127 5128 _gc_tracer_stw->report_gc_reference_stats(stats); 5129 5130 // We have completed copying any necessary live referent objects. 5131 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 5132 5133 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5134 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5135 } 5136 5137 // Weak Reference processing during an evacuation pause (part 2). 5138 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 5139 double ref_enq_start = os::elapsedTime(); 5140 5141 ReferenceProcessor* rp = _ref_processor_stw; 5142 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5143 5144 // Now enqueue any remaining on the discovered lists on to 5145 // the pending list. 5146 if (!rp->processing_is_mt()) { 5147 // Serial reference processing... 5148 rp->enqueue_discovered_references(); 5149 } else { 5150 // Parallel reference enqueueing 5151 5152 uint n_workers = workers()->active_workers(); 5153 5154 assert(rp->num_q() == n_workers, "sanity"); 5155 assert(n_workers <= rp->max_num_q(), "sanity"); 5156 5157 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers); 5158 rp->enqueue_discovered_references(&par_task_executor); 5159 } 5160 5161 rp->verify_no_references_recorded(); 5162 assert(!rp->discovery_enabled(), "should have been disabled"); 5163 5164 // FIXME 5165 // CM's reference processing also cleans up the string and symbol tables. 5166 // Should we do that here also? We could, but it is a serial operation 5167 // and could significantly increase the pause time. 5168 5169 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5170 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5171 } 5172 5173 void G1CollectedHeap::pre_evacuate_collection_set() { 5174 _expand_heap_after_alloc_failure = true; 5175 _evacuation_failed = false; 5176 5177 // Disable the hot card cache. 5178 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5179 hot_card_cache->reset_hot_cache_claimed_index(); 5180 hot_card_cache->set_use_cache(false); 5181 5182 } 5183 5184 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 5185 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5186 5187 // Should G1EvacuationFailureALot be in effect for this GC? 5188 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5189 5190 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5191 double start_par_time_sec = os::elapsedTime(); 5192 double end_par_time_sec; 5193 5194 { 5195 const uint n_workers = workers()->active_workers(); 5196 G1RootProcessor root_processor(this, n_workers); 5197 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 5198 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5199 if (collector_state()->during_initial_mark_pause()) { 5200 ClassLoaderDataGraph::clear_claimed_marks(); 5201 } 5202 5203 // The individual threads will set their evac-failure closures. 5204 if (PrintTerminationStats) { 5205 print_termination_stats_hdr(gclog_or_tty); 5206 } 5207 5208 workers()->run_task(&g1_par_task); 5209 end_par_time_sec = os::elapsedTime(); 5210 5211 // Closing the inner scope will execute the destructor 5212 // for the G1RootProcessor object. We record the current 5213 // elapsed time before closing the scope so that time 5214 // taken for the destructor is NOT included in the 5215 // reported parallel time. 5216 } 5217 5218 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 5219 5220 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5221 phase_times->record_par_time(par_time_ms); 5222 5223 double code_root_fixup_time_ms = 5224 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5225 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 5226 5227 // Process any discovered reference objects - we have 5228 // to do this _before_ we retire the GC alloc regions 5229 // as we may have to copy some 'reachable' referent 5230 // objects (and their reachable sub-graphs) that were 5231 // not copied during the pause. 5232 process_discovered_references(per_thread_states); 5233 5234 if (G1StringDedup::is_enabled()) { 5235 double fixup_start = os::elapsedTime(); 5236 5237 G1STWIsAliveClosure is_alive(this); 5238 G1KeepAliveClosure keep_alive(this); 5239 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times); 5240 5241 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 5242 phase_times->record_string_dedup_fixup_time(fixup_time_ms); 5243 } 5244 5245 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5246 5247 if (evacuation_failed()) { 5248 remove_self_forwarding_pointers(); 5249 5250 // Reset the G1EvacuationFailureALot counters and flags 5251 // Note: the values are reset only when an actual 5252 // evacuation failure occurs. 5253 NOT_PRODUCT(reset_evacuation_should_fail();) 5254 } 5255 5256 // Enqueue any remaining references remaining on the STW 5257 // reference processor's discovered lists. We need to do 5258 // this after the card table is cleaned (and verified) as 5259 // the act of enqueueing entries on to the pending list 5260 // will log these updates (and dirty their associated 5261 // cards). We need these updates logged to update any 5262 // RSets. 5263 enqueue_discovered_references(per_thread_states); 5264 } 5265 5266 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 5267 _allocator->release_gc_alloc_regions(evacuation_info); 5268 5269 per_thread_states->flush(); 5270 5271 record_obj_copy_mem_stats(); 5272 5273 _survivor_evac_stats.adjust_desired_plab_sz(); 5274 _old_evac_stats.adjust_desired_plab_sz(); 5275 5276 // Reset and re-enable the hot card cache. 5277 // Note the counts for the cards in the regions in the 5278 // collection set are reset when the collection set is freed. 5279 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5280 hot_card_cache->reset_hot_cache(); 5281 hot_card_cache->set_use_cache(true); 5282 5283 purge_code_root_memory(); 5284 5285 redirty_logged_cards(); 5286 #if defined(COMPILER2) || INCLUDE_JVMCI 5287 DerivedPointerTable::update_pointers(); 5288 #endif 5289 } 5290 5291 void G1CollectedHeap::record_obj_copy_mem_stats() { 5292 g1_policy()->add_last_old_allocated_bytes(_old_evac_stats.allocated() * HeapWordSize); 5293 5294 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 5295 create_g1_evac_summary(&_old_evac_stats)); 5296 } 5297 5298 void G1CollectedHeap::free_region(HeapRegion* hr, 5299 FreeRegionList* free_list, 5300 bool par, 5301 bool locked) { 5302 assert(!hr->is_free(), "the region should not be free"); 5303 assert(!hr->is_empty(), "the region should not be empty"); 5304 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 5305 assert(free_list != NULL, "pre-condition"); 5306 5307 if (G1VerifyBitmaps) { 5308 MemRegion mr(hr->bottom(), hr->end()); 5309 concurrent_mark()->clearRangePrevBitmap(mr); 5310 } 5311 5312 // Clear the card counts for this region. 5313 // Note: we only need to do this if the region is not young 5314 // (since we don't refine cards in young regions). 5315 if (!hr->is_young()) { 5316 _cg1r->hot_card_cache()->reset_card_counts(hr); 5317 } 5318 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5319 free_list->add_ordered(hr); 5320 } 5321 5322 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5323 FreeRegionList* free_list, 5324 bool par) { 5325 assert(hr->is_starts_humongous(), "this is only for starts humongous regions"); 5326 assert(free_list != NULL, "pre-condition"); 5327 5328 size_t hr_capacity = hr->capacity(); 5329 // We need to read this before we make the region non-humongous, 5330 // otherwise the information will be gone. 5331 uint last_index = hr->last_hc_index(); 5332 hr->clear_humongous(); 5333 free_region(hr, free_list, par); 5334 5335 uint i = hr->hrm_index() + 1; 5336 while (i < last_index) { 5337 HeapRegion* curr_hr = region_at(i); 5338 assert(curr_hr->is_continues_humongous(), "invariant"); 5339 curr_hr->clear_humongous(); 5340 free_region(curr_hr, free_list, par); 5341 i += 1; 5342 } 5343 } 5344 5345 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 5346 const HeapRegionSetCount& humongous_regions_removed) { 5347 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5348 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5349 _old_set.bulk_remove(old_regions_removed); 5350 _humongous_set.bulk_remove(humongous_regions_removed); 5351 } 5352 5353 } 5354 5355 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 5356 assert(list != NULL, "list can't be null"); 5357 if (!list->is_empty()) { 5358 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5359 _hrm.insert_list_into_free_list(list); 5360 } 5361 } 5362 5363 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 5364 decrease_used(bytes); 5365 } 5366 5367 class G1ParCleanupCTTask : public AbstractGangTask { 5368 G1SATBCardTableModRefBS* _ct_bs; 5369 G1CollectedHeap* _g1h; 5370 HeapRegion* volatile _su_head; 5371 public: 5372 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 5373 G1CollectedHeap* g1h) : 5374 AbstractGangTask("G1 Par Cleanup CT Task"), 5375 _ct_bs(ct_bs), _g1h(g1h) { } 5376 5377 void work(uint worker_id) { 5378 HeapRegion* r; 5379 while (r = _g1h->pop_dirty_cards_region()) { 5380 clear_cards(r); 5381 } 5382 } 5383 5384 void clear_cards(HeapRegion* r) { 5385 // Cards of the survivors should have already been dirtied. 5386 if (!r->is_survivor()) { 5387 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5388 } 5389 } 5390 }; 5391 5392 #ifndef PRODUCT 5393 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5394 G1CollectedHeap* _g1h; 5395 G1SATBCardTableModRefBS* _ct_bs; 5396 public: 5397 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 5398 : _g1h(g1h), _ct_bs(ct_bs) { } 5399 virtual bool doHeapRegion(HeapRegion* r) { 5400 if (r->is_survivor()) { 5401 _g1h->verify_dirty_region(r); 5402 } else { 5403 _g1h->verify_not_dirty_region(r); 5404 } 5405 return false; 5406 } 5407 }; 5408 5409 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5410 // All of the region should be clean. 5411 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5412 MemRegion mr(hr->bottom(), hr->end()); 5413 ct_bs->verify_not_dirty_region(mr); 5414 } 5415 5416 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5417 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5418 // dirty allocated blocks as they allocate them. The thread that 5419 // retires each region and replaces it with a new one will do a 5420 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5421 // not dirty that area (one less thing to have to do while holding 5422 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5423 // is dirty. 5424 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5425 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5426 if (hr->is_young()) { 5427 ct_bs->verify_g1_young_region(mr); 5428 } else { 5429 ct_bs->verify_dirty_region(mr); 5430 } 5431 } 5432 5433 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5434 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5435 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5436 verify_dirty_region(hr); 5437 } 5438 } 5439 5440 void G1CollectedHeap::verify_dirty_young_regions() { 5441 verify_dirty_young_list(_young_list->first_region()); 5442 } 5443 5444 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 5445 HeapWord* tams, HeapWord* end) { 5446 guarantee(tams <= end, 5447 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end)); 5448 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 5449 if (result < end) { 5450 gclog_or_tty->cr(); 5451 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT, 5452 bitmap_name, p2i(result)); 5453 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT, 5454 bitmap_name, p2i(tams), p2i(end)); 5455 return false; 5456 } 5457 return true; 5458 } 5459 5460 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 5461 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 5462 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 5463 5464 HeapWord* bottom = hr->bottom(); 5465 HeapWord* ptams = hr->prev_top_at_mark_start(); 5466 HeapWord* ntams = hr->next_top_at_mark_start(); 5467 HeapWord* end = hr->end(); 5468 5469 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 5470 5471 bool res_n = true; 5472 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 5473 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 5474 // if we happen to be in that state. 5475 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) { 5476 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 5477 } 5478 if (!res_p || !res_n) { 5479 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT, 5480 HR_FORMAT_PARAMS(hr)); 5481 gclog_or_tty->print_cr("#### Caller: %s", caller); 5482 return false; 5483 } 5484 return true; 5485 } 5486 5487 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 5488 if (!G1VerifyBitmaps) return; 5489 5490 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 5491 } 5492 5493 class G1VerifyBitmapClosure : public HeapRegionClosure { 5494 private: 5495 const char* _caller; 5496 G1CollectedHeap* _g1h; 5497 bool _failures; 5498 5499 public: 5500 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 5501 _caller(caller), _g1h(g1h), _failures(false) { } 5502 5503 bool failures() { return _failures; } 5504 5505 virtual bool doHeapRegion(HeapRegion* hr) { 5506 if (hr->is_continues_humongous()) return false; 5507 5508 bool result = _g1h->verify_bitmaps(_caller, hr); 5509 if (!result) { 5510 _failures = true; 5511 } 5512 return false; 5513 } 5514 }; 5515 5516 void G1CollectedHeap::check_bitmaps(const char* caller) { 5517 if (!G1VerifyBitmaps) return; 5518 5519 G1VerifyBitmapClosure cl(caller, this); 5520 heap_region_iterate(&cl); 5521 guarantee(!cl.failures(), "bitmap verification"); 5522 } 5523 5524 class G1CheckCSetFastTableClosure : public HeapRegionClosure { 5525 private: 5526 bool _failures; 5527 public: 5528 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { } 5529 5530 virtual bool doHeapRegion(HeapRegion* hr) { 5531 uint i = hr->hrm_index(); 5532 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i); 5533 if (hr->is_humongous()) { 5534 if (hr->in_collection_set()) { 5535 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i); 5536 _failures = true; 5537 return true; 5538 } 5539 if (cset_state.is_in_cset()) { 5540 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i); 5541 _failures = true; 5542 return true; 5543 } 5544 if (hr->is_continues_humongous() && cset_state.is_humongous()) { 5545 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i); 5546 _failures = true; 5547 return true; 5548 } 5549 } else { 5550 if (cset_state.is_humongous()) { 5551 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i); 5552 _failures = true; 5553 return true; 5554 } 5555 if (hr->in_collection_set() != cset_state.is_in_cset()) { 5556 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u", 5557 hr->in_collection_set(), cset_state.value(), i); 5558 _failures = true; 5559 return true; 5560 } 5561 if (cset_state.is_in_cset()) { 5562 if (hr->is_young() != (cset_state.is_young())) { 5563 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u", 5564 hr->is_young(), cset_state.value(), i); 5565 _failures = true; 5566 return true; 5567 } 5568 if (hr->is_old() != (cset_state.is_old())) { 5569 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u", 5570 hr->is_old(), cset_state.value(), i); 5571 _failures = true; 5572 return true; 5573 } 5574 } 5575 } 5576 return false; 5577 } 5578 5579 bool failures() const { return _failures; } 5580 }; 5581 5582 bool G1CollectedHeap::check_cset_fast_test() { 5583 G1CheckCSetFastTableClosure cl; 5584 _hrm.iterate(&cl); 5585 return !cl.failures(); 5586 } 5587 #endif // PRODUCT 5588 5589 void G1CollectedHeap::cleanUpCardTable() { 5590 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5591 double start = os::elapsedTime(); 5592 5593 { 5594 // Iterate over the dirty cards region list. 5595 G1ParCleanupCTTask cleanup_task(ct_bs, this); 5596 5597 workers()->run_task(&cleanup_task); 5598 #ifndef PRODUCT 5599 if (G1VerifyCTCleanup || VerifyAfterGC) { 5600 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 5601 heap_region_iterate(&cleanup_verifier); 5602 } 5603 #endif 5604 } 5605 5606 double elapsed = os::elapsedTime() - start; 5607 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 5608 } 5609 5610 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 5611 size_t pre_used = 0; 5612 FreeRegionList local_free_list("Local List for CSet Freeing"); 5613 5614 double young_time_ms = 0.0; 5615 double non_young_time_ms = 0.0; 5616 5617 // Since the collection set is a superset of the the young list, 5618 // all we need to do to clear the young list is clear its 5619 // head and length, and unlink any young regions in the code below 5620 _young_list->clear(); 5621 5622 G1CollectorPolicy* policy = g1_policy(); 5623 5624 double start_sec = os::elapsedTime(); 5625 bool non_young = true; 5626 5627 HeapRegion* cur = cs_head; 5628 int age_bound = -1; 5629 size_t rs_lengths = 0; 5630 5631 while (cur != NULL) { 5632 assert(!is_on_master_free_list(cur), "sanity"); 5633 if (non_young) { 5634 if (cur->is_young()) { 5635 double end_sec = os::elapsedTime(); 5636 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5637 non_young_time_ms += elapsed_ms; 5638 5639 start_sec = os::elapsedTime(); 5640 non_young = false; 5641 } 5642 } else { 5643 if (!cur->is_young()) { 5644 double end_sec = os::elapsedTime(); 5645 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5646 young_time_ms += elapsed_ms; 5647 5648 start_sec = os::elapsedTime(); 5649 non_young = true; 5650 } 5651 } 5652 5653 rs_lengths += cur->rem_set()->occupied_locked(); 5654 5655 HeapRegion* next = cur->next_in_collection_set(); 5656 assert(cur->in_collection_set(), "bad CS"); 5657 cur->set_next_in_collection_set(NULL); 5658 clear_in_cset(cur); 5659 5660 if (cur->is_young()) { 5661 int index = cur->young_index_in_cset(); 5662 assert(index != -1, "invariant"); 5663 assert((uint) index < policy->young_cset_region_length(), "invariant"); 5664 size_t words_survived = surviving_young_words[index]; 5665 cur->record_surv_words_in_group(words_survived); 5666 5667 // At this point the we have 'popped' cur from the collection set 5668 // (linked via next_in_collection_set()) but it is still in the 5669 // young list (linked via next_young_region()). Clear the 5670 // _next_young_region field. 5671 cur->set_next_young_region(NULL); 5672 } else { 5673 int index = cur->young_index_in_cset(); 5674 assert(index == -1, "invariant"); 5675 } 5676 5677 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 5678 (!cur->is_young() && cur->young_index_in_cset() == -1), 5679 "invariant" ); 5680 5681 if (!cur->evacuation_failed()) { 5682 MemRegion used_mr = cur->used_region(); 5683 5684 // And the region is empty. 5685 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 5686 pre_used += cur->used(); 5687 free_region(cur, &local_free_list, false /* par */, true /* locked */); 5688 } else { 5689 cur->uninstall_surv_rate_group(); 5690 if (cur->is_young()) { 5691 cur->set_young_index_in_cset(-1); 5692 } 5693 cur->set_evacuation_failed(false); 5694 // The region is now considered to be old. 5695 cur->set_old(); 5696 // Do some allocation statistics accounting. Regions that failed evacuation 5697 // are always made old, so there is no need to update anything in the young 5698 // gen statistics, but we need to update old gen statistics. 5699 size_t used_words = cur->marked_bytes() / HeapWordSize; 5700 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words); 5701 _old_set.add(cur); 5702 evacuation_info.increment_collectionset_used_after(cur->used()); 5703 } 5704 cur = next; 5705 } 5706 5707 evacuation_info.set_regions_freed(local_free_list.length()); 5708 policy->record_max_rs_lengths(rs_lengths); 5709 policy->cset_regions_freed(); 5710 5711 double end_sec = os::elapsedTime(); 5712 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5713 5714 if (non_young) { 5715 non_young_time_ms += elapsed_ms; 5716 } else { 5717 young_time_ms += elapsed_ms; 5718 } 5719 5720 prepend_to_freelist(&local_free_list); 5721 decrement_summary_bytes(pre_used); 5722 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 5723 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 5724 } 5725 5726 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 5727 private: 5728 FreeRegionList* _free_region_list; 5729 HeapRegionSet* _proxy_set; 5730 HeapRegionSetCount _humongous_regions_removed; 5731 size_t _freed_bytes; 5732 public: 5733 5734 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 5735 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 5736 } 5737 5738 virtual bool doHeapRegion(HeapRegion* r) { 5739 if (!r->is_starts_humongous()) { 5740 return false; 5741 } 5742 5743 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 5744 5745 oop obj = (oop)r->bottom(); 5746 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 5747 5748 // The following checks whether the humongous object is live are sufficient. 5749 // The main additional check (in addition to having a reference from the roots 5750 // or the young gen) is whether the humongous object has a remembered set entry. 5751 // 5752 // A humongous object cannot be live if there is no remembered set for it 5753 // because: 5754 // - there can be no references from within humongous starts regions referencing 5755 // the object because we never allocate other objects into them. 5756 // (I.e. there are no intra-region references that may be missed by the 5757 // remembered set) 5758 // - as soon there is a remembered set entry to the humongous starts region 5759 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 5760 // until the end of a concurrent mark. 5761 // 5762 // It is not required to check whether the object has been found dead by marking 5763 // or not, in fact it would prevent reclamation within a concurrent cycle, as 5764 // all objects allocated during that time are considered live. 5765 // SATB marking is even more conservative than the remembered set. 5766 // So if at this point in the collection there is no remembered set entry, 5767 // nobody has a reference to it. 5768 // At the start of collection we flush all refinement logs, and remembered sets 5769 // are completely up-to-date wrt to references to the humongous object. 5770 // 5771 // Other implementation considerations: 5772 // - never consider object arrays at this time because they would pose 5773 // considerable effort for cleaning up the the remembered sets. This is 5774 // required because stale remembered sets might reference locations that 5775 // are currently allocated into. 5776 uint region_idx = r->hrm_index(); 5777 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 5778 !r->rem_set()->is_empty()) { 5779 5780 if (G1TraceEagerReclaimHumongousObjects) { 5781 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", 5782 region_idx, 5783 (size_t)obj->size() * HeapWordSize, 5784 p2i(r->bottom()), 5785 r->region_num(), 5786 r->rem_set()->occupied(), 5787 r->rem_set()->strong_code_roots_list_length(), 5788 next_bitmap->isMarked(r->bottom()), 5789 g1h->is_humongous_reclaim_candidate(region_idx), 5790 obj->is_typeArray() 5791 ); 5792 } 5793 5794 return false; 5795 } 5796 5797 guarantee(obj->is_typeArray(), 5798 "Only eagerly reclaiming type arrays is supported, but the object " 5799 PTR_FORMAT " is not.", p2i(r->bottom())); 5800 5801 if (G1TraceEagerReclaimHumongousObjects) { 5802 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", 5803 region_idx, 5804 (size_t)obj->size() * HeapWordSize, 5805 p2i(r->bottom()), 5806 r->region_num(), 5807 r->rem_set()->occupied(), 5808 r->rem_set()->strong_code_roots_list_length(), 5809 next_bitmap->isMarked(r->bottom()), 5810 g1h->is_humongous_reclaim_candidate(region_idx), 5811 obj->is_typeArray() 5812 ); 5813 } 5814 // Need to clear mark bit of the humongous object if already set. 5815 if (next_bitmap->isMarked(r->bottom())) { 5816 next_bitmap->clear(r->bottom()); 5817 } 5818 _freed_bytes += r->used(); 5819 r->set_containing_set(NULL); 5820 _humongous_regions_removed.increment(1u, r->capacity()); 5821 g1h->free_humongous_region(r, _free_region_list, false); 5822 5823 return false; 5824 } 5825 5826 HeapRegionSetCount& humongous_free_count() { 5827 return _humongous_regions_removed; 5828 } 5829 5830 size_t bytes_freed() const { 5831 return _freed_bytes; 5832 } 5833 5834 size_t humongous_reclaimed() const { 5835 return _humongous_regions_removed.length(); 5836 } 5837 }; 5838 5839 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 5840 assert_at_safepoint(true); 5841 5842 if (!G1EagerReclaimHumongousObjects || 5843 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) { 5844 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 5845 return; 5846 } 5847 5848 double start_time = os::elapsedTime(); 5849 5850 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 5851 5852 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 5853 heap_region_iterate(&cl); 5854 5855 HeapRegionSetCount empty_set; 5856 remove_from_old_sets(empty_set, cl.humongous_free_count()); 5857 5858 G1HRPrinter* hrp = hr_printer(); 5859 if (hrp->is_active()) { 5860 FreeRegionListIterator iter(&local_cleanup_list); 5861 while (iter.more_available()) { 5862 HeapRegion* hr = iter.get_next(); 5863 hrp->cleanup(hr); 5864 } 5865 } 5866 5867 prepend_to_freelist(&local_cleanup_list); 5868 decrement_summary_bytes(cl.bytes_freed()); 5869 5870 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 5871 cl.humongous_reclaimed()); 5872 } 5873 5874 // This routine is similar to the above but does not record 5875 // any policy statistics or update free lists; we are abandoning 5876 // the current incremental collection set in preparation of a 5877 // full collection. After the full GC we will start to build up 5878 // the incremental collection set again. 5879 // This is only called when we're doing a full collection 5880 // and is immediately followed by the tearing down of the young list. 5881 5882 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 5883 HeapRegion* cur = cs_head; 5884 5885 while (cur != NULL) { 5886 HeapRegion* next = cur->next_in_collection_set(); 5887 assert(cur->in_collection_set(), "bad CS"); 5888 cur->set_next_in_collection_set(NULL); 5889 clear_in_cset(cur); 5890 cur->set_young_index_in_cset(-1); 5891 cur = next; 5892 } 5893 } 5894 5895 void G1CollectedHeap::set_free_regions_coming() { 5896 if (G1ConcRegionFreeingVerbose) { 5897 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 5898 "setting free regions coming"); 5899 } 5900 5901 assert(!free_regions_coming(), "pre-condition"); 5902 _free_regions_coming = true; 5903 } 5904 5905 void G1CollectedHeap::reset_free_regions_coming() { 5906 assert(free_regions_coming(), "pre-condition"); 5907 5908 { 5909 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5910 _free_regions_coming = false; 5911 SecondaryFreeList_lock->notify_all(); 5912 } 5913 5914 if (G1ConcRegionFreeingVerbose) { 5915 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 5916 "reset free regions coming"); 5917 } 5918 } 5919 5920 void G1CollectedHeap::wait_while_free_regions_coming() { 5921 // Most of the time we won't have to wait, so let's do a quick test 5922 // first before we take the lock. 5923 if (!free_regions_coming()) { 5924 return; 5925 } 5926 5927 if (G1ConcRegionFreeingVerbose) { 5928 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 5929 "waiting for free regions"); 5930 } 5931 5932 { 5933 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5934 while (free_regions_coming()) { 5935 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 5936 } 5937 } 5938 5939 if (G1ConcRegionFreeingVerbose) { 5940 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 5941 "done waiting for free regions"); 5942 } 5943 } 5944 5945 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 5946 return _allocator->is_retained_old_region(hr); 5947 } 5948 5949 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 5950 _young_list->push_region(hr); 5951 } 5952 5953 class NoYoungRegionsClosure: public HeapRegionClosure { 5954 private: 5955 bool _success; 5956 public: 5957 NoYoungRegionsClosure() : _success(true) { } 5958 bool doHeapRegion(HeapRegion* r) { 5959 if (r->is_young()) { 5960 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 5961 p2i(r->bottom()), p2i(r->end())); 5962 _success = false; 5963 } 5964 return false; 5965 } 5966 bool success() { return _success; } 5967 }; 5968 5969 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 5970 bool ret = _young_list->check_list_empty(check_sample); 5971 5972 if (check_heap) { 5973 NoYoungRegionsClosure closure; 5974 heap_region_iterate(&closure); 5975 ret = ret && closure.success(); 5976 } 5977 5978 return ret; 5979 } 5980 5981 class TearDownRegionSetsClosure : public HeapRegionClosure { 5982 private: 5983 HeapRegionSet *_old_set; 5984 5985 public: 5986 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 5987 5988 bool doHeapRegion(HeapRegion* r) { 5989 if (r->is_old()) { 5990 _old_set->remove(r); 5991 } else { 5992 // We ignore free regions, we'll empty the free list afterwards. 5993 // We ignore young regions, we'll empty the young list afterwards. 5994 // We ignore humongous regions, we're not tearing down the 5995 // humongous regions set. 5996 assert(r->is_free() || r->is_young() || r->is_humongous(), 5997 "it cannot be another type"); 5998 } 5999 return false; 6000 } 6001 6002 ~TearDownRegionSetsClosure() { 6003 assert(_old_set->is_empty(), "post-condition"); 6004 } 6005 }; 6006 6007 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6008 assert_at_safepoint(true /* should_be_vm_thread */); 6009 6010 if (!free_list_only) { 6011 TearDownRegionSetsClosure cl(&_old_set); 6012 heap_region_iterate(&cl); 6013 6014 // Note that emptying the _young_list is postponed and instead done as 6015 // the first step when rebuilding the regions sets again. The reason for 6016 // this is that during a full GC string deduplication needs to know if 6017 // a collected region was young or old when the full GC was initiated. 6018 } 6019 _hrm.remove_all_free_regions(); 6020 } 6021 6022 void G1CollectedHeap::increase_used(size_t bytes) { 6023 _summary_bytes_used += bytes; 6024 } 6025 6026 void G1CollectedHeap::decrease_used(size_t bytes) { 6027 assert(_summary_bytes_used >= bytes, 6028 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 6029 _summary_bytes_used, bytes); 6030 _summary_bytes_used -= bytes; 6031 } 6032 6033 void G1CollectedHeap::set_used(size_t bytes) { 6034 _summary_bytes_used = bytes; 6035 } 6036 6037 class RebuildRegionSetsClosure : public HeapRegionClosure { 6038 private: 6039 bool _free_list_only; 6040 HeapRegionSet* _old_set; 6041 HeapRegionManager* _hrm; 6042 size_t _total_used; 6043 6044 public: 6045 RebuildRegionSetsClosure(bool free_list_only, 6046 HeapRegionSet* old_set, HeapRegionManager* hrm) : 6047 _free_list_only(free_list_only), 6048 _old_set(old_set), _hrm(hrm), _total_used(0) { 6049 assert(_hrm->num_free_regions() == 0, "pre-condition"); 6050 if (!free_list_only) { 6051 assert(_old_set->is_empty(), "pre-condition"); 6052 } 6053 } 6054 6055 bool doHeapRegion(HeapRegion* r) { 6056 if (r->is_continues_humongous()) { 6057 return false; 6058 } 6059 6060 if (r->is_empty()) { 6061 // Add free regions to the free list 6062 r->set_free(); 6063 r->set_allocation_context(AllocationContext::system()); 6064 _hrm->insert_into_free_list(r); 6065 } else if (!_free_list_only) { 6066 assert(!r->is_young(), "we should not come across young regions"); 6067 6068 if (r->is_humongous()) { 6069 // We ignore humongous regions. We left the humongous set unchanged. 6070 } else { 6071 // Objects that were compacted would have ended up on regions 6072 // that were previously old or free. Archive regions (which are 6073 // old) will not have been touched. 6074 assert(r->is_free() || r->is_old(), "invariant"); 6075 // We now consider them old, so register as such. Leave 6076 // archive regions set that way, however, while still adding 6077 // them to the old set. 6078 if (!r->is_archive()) { 6079 r->set_old(); 6080 } 6081 _old_set->add(r); 6082 } 6083 _total_used += r->used(); 6084 } 6085 6086 return false; 6087 } 6088 6089 size_t total_used() { 6090 return _total_used; 6091 } 6092 }; 6093 6094 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6095 assert_at_safepoint(true /* should_be_vm_thread */); 6096 6097 if (!free_list_only) { 6098 _young_list->empty_list(); 6099 } 6100 6101 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 6102 heap_region_iterate(&cl); 6103 6104 if (!free_list_only) { 6105 set_used(cl.total_used()); 6106 if (_archive_allocator != NULL) { 6107 _archive_allocator->clear_used(); 6108 } 6109 } 6110 assert(used_unlocked() == recalculate_used(), 6111 "inconsistent used_unlocked(), " 6112 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 6113 used_unlocked(), recalculate_used()); 6114 } 6115 6116 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6117 _refine_cte_cl->set_concurrent(concurrent); 6118 } 6119 6120 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6121 HeapRegion* hr = heap_region_containing(p); 6122 return hr->is_in(p); 6123 } 6124 6125 // Methods for the mutator alloc region 6126 6127 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6128 bool force) { 6129 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6130 assert(!force || g1_policy()->can_expand_young_list(), 6131 "if force is true we should be able to expand the young list"); 6132 bool young_list_full = g1_policy()->is_young_list_full(); 6133 if (force || !young_list_full) { 6134 HeapRegion* new_alloc_region = new_region(word_size, 6135 false /* is_old */, 6136 false /* do_expand */); 6137 if (new_alloc_region != NULL) { 6138 set_region_short_lived_locked(new_alloc_region); 6139 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6140 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6141 return new_alloc_region; 6142 } 6143 } 6144 return NULL; 6145 } 6146 6147 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6148 size_t allocated_bytes) { 6149 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6150 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 6151 6152 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6153 increase_used(allocated_bytes); 6154 _hr_printer.retire(alloc_region); 6155 // We update the eden sizes here, when the region is retired, 6156 // instead of when it's allocated, since this is the point that its 6157 // used space has been recored in _summary_bytes_used. 6158 g1mm()->update_eden_size(); 6159 } 6160 6161 // Methods for the GC alloc regions 6162 6163 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6164 uint count, 6165 InCSetState dest) { 6166 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6167 6168 if (count < g1_policy()->max_regions(dest)) { 6169 const bool is_survivor = (dest.is_young()); 6170 HeapRegion* new_alloc_region = new_region(word_size, 6171 !is_survivor, 6172 true /* do_expand */); 6173 if (new_alloc_region != NULL) { 6174 // We really only need to do this for old regions given that we 6175 // should never scan survivors. But it doesn't hurt to do it 6176 // for survivors too. 6177 new_alloc_region->record_timestamp(); 6178 if (is_survivor) { 6179 new_alloc_region->set_survivor(); 6180 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6181 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6182 } else { 6183 new_alloc_region->set_old(); 6184 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6185 check_bitmaps("Old Region Allocation", new_alloc_region); 6186 } 6187 bool during_im = collector_state()->during_initial_mark_pause(); 6188 new_alloc_region->note_start_of_copying(during_im); 6189 return new_alloc_region; 6190 } 6191 } 6192 return NULL; 6193 } 6194 6195 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6196 size_t allocated_bytes, 6197 InCSetState dest) { 6198 bool during_im = collector_state()->during_initial_mark_pause(); 6199 alloc_region->note_end_of_copying(during_im); 6200 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6201 if (dest.is_young()) { 6202 young_list()->add_survivor_region(alloc_region); 6203 } else { 6204 _old_set.add(alloc_region); 6205 } 6206 _hr_printer.retire(alloc_region); 6207 } 6208 6209 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 6210 bool expanded = false; 6211 uint index = _hrm.find_highest_free(&expanded); 6212 6213 if (index != G1_NO_HRM_INDEX) { 6214 if (expanded) { 6215 ergo_verbose1(ErgoHeapSizing, 6216 "attempt heap expansion", 6217 ergo_format_reason("requested address range outside heap bounds") 6218 ergo_format_byte("region size"), 6219 HeapRegion::GrainWords * HeapWordSize); 6220 } 6221 _hrm.allocate_free_regions_starting_at(index, 1); 6222 return region_at(index); 6223 } 6224 return NULL; 6225 } 6226 6227 // Heap region set verification 6228 6229 class VerifyRegionListsClosure : public HeapRegionClosure { 6230 private: 6231 HeapRegionSet* _old_set; 6232 HeapRegionSet* _humongous_set; 6233 HeapRegionManager* _hrm; 6234 6235 public: 6236 HeapRegionSetCount _old_count; 6237 HeapRegionSetCount _humongous_count; 6238 HeapRegionSetCount _free_count; 6239 6240 VerifyRegionListsClosure(HeapRegionSet* old_set, 6241 HeapRegionSet* humongous_set, 6242 HeapRegionManager* hrm) : 6243 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm), 6244 _old_count(), _humongous_count(), _free_count(){ } 6245 6246 bool doHeapRegion(HeapRegion* hr) { 6247 if (hr->is_continues_humongous()) { 6248 return false; 6249 } 6250 6251 if (hr->is_young()) { 6252 // TODO 6253 } else if (hr->is_starts_humongous()) { 6254 assert(hr->containing_set() == _humongous_set, "Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()); 6255 _humongous_count.increment(1u, hr->capacity()); 6256 } else if (hr->is_empty()) { 6257 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index()); 6258 _free_count.increment(1u, hr->capacity()); 6259 } else if (hr->is_old()) { 6260 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index()); 6261 _old_count.increment(1u, hr->capacity()); 6262 } else { 6263 // There are no other valid region types. Check for one invalid 6264 // one we can identify: pinned without old or humongous set. 6265 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index()); 6266 ShouldNotReachHere(); 6267 } 6268 return false; 6269 } 6270 6271 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) { 6272 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()); 6273 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6274 old_set->total_capacity_bytes(), _old_count.capacity()); 6275 6276 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()); 6277 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6278 humongous_set->total_capacity_bytes(), _humongous_count.capacity()); 6279 6280 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()); 6281 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6282 free_list->total_capacity_bytes(), _free_count.capacity()); 6283 } 6284 }; 6285 6286 void G1CollectedHeap::verify_region_sets() { 6287 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6288 6289 // First, check the explicit lists. 6290 _hrm.verify(); 6291 { 6292 // Given that a concurrent operation might be adding regions to 6293 // the secondary free list we have to take the lock before 6294 // verifying it. 6295 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6296 _secondary_free_list.verify_list(); 6297 } 6298 6299 // If a concurrent region freeing operation is in progress it will 6300 // be difficult to correctly attributed any free regions we come 6301 // across to the correct free list given that they might belong to 6302 // one of several (free_list, secondary_free_list, any local lists, 6303 // etc.). So, if that's the case we will skip the rest of the 6304 // verification operation. Alternatively, waiting for the concurrent 6305 // operation to complete will have a non-trivial effect on the GC's 6306 // operation (no concurrent operation will last longer than the 6307 // interval between two calls to verification) and it might hide 6308 // any issues that we would like to catch during testing. 6309 if (free_regions_coming()) { 6310 return; 6311 } 6312 6313 // Make sure we append the secondary_free_list on the free_list so 6314 // that all free regions we will come across can be safely 6315 // attributed to the free_list. 6316 append_secondary_free_list_if_not_empty_with_lock(); 6317 6318 // Finally, make sure that the region accounting in the lists is 6319 // consistent with what we see in the heap. 6320 6321 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm); 6322 heap_region_iterate(&cl); 6323 cl.verify_counts(&_old_set, &_humongous_set, &_hrm); 6324 } 6325 6326 // Optimized nmethod scanning 6327 6328 class RegisterNMethodOopClosure: public OopClosure { 6329 G1CollectedHeap* _g1h; 6330 nmethod* _nm; 6331 6332 template <class T> void do_oop_work(T* p) { 6333 T heap_oop = oopDesc::load_heap_oop(p); 6334 if (!oopDesc::is_null(heap_oop)) { 6335 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6336 HeapRegion* hr = _g1h->heap_region_containing(obj); 6337 assert(!hr->is_continues_humongous(), 6338 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 6339 " starting at " HR_FORMAT, 6340 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 6341 6342 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 6343 hr->add_strong_code_root_locked(_nm); 6344 } 6345 } 6346 6347 public: 6348 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6349 _g1h(g1h), _nm(nm) {} 6350 6351 void do_oop(oop* p) { do_oop_work(p); } 6352 void do_oop(narrowOop* p) { do_oop_work(p); } 6353 }; 6354 6355 class UnregisterNMethodOopClosure: public OopClosure { 6356 G1CollectedHeap* _g1h; 6357 nmethod* _nm; 6358 6359 template <class T> void do_oop_work(T* p) { 6360 T heap_oop = oopDesc::load_heap_oop(p); 6361 if (!oopDesc::is_null(heap_oop)) { 6362 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6363 HeapRegion* hr = _g1h->heap_region_containing(obj); 6364 assert(!hr->is_continues_humongous(), 6365 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 6366 " starting at " HR_FORMAT, 6367 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 6368 6369 hr->remove_strong_code_root(_nm); 6370 } 6371 } 6372 6373 public: 6374 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6375 _g1h(g1h), _nm(nm) {} 6376 6377 void do_oop(oop* p) { do_oop_work(p); } 6378 void do_oop(narrowOop* p) { do_oop_work(p); } 6379 }; 6380 6381 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6382 CollectedHeap::register_nmethod(nm); 6383 6384 guarantee(nm != NULL, "sanity"); 6385 RegisterNMethodOopClosure reg_cl(this, nm); 6386 nm->oops_do(®_cl); 6387 } 6388 6389 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6390 CollectedHeap::unregister_nmethod(nm); 6391 6392 guarantee(nm != NULL, "sanity"); 6393 UnregisterNMethodOopClosure reg_cl(this, nm); 6394 nm->oops_do(®_cl, true); 6395 } 6396 6397 void G1CollectedHeap::purge_code_root_memory() { 6398 double purge_start = os::elapsedTime(); 6399 G1CodeRootSet::purge(); 6400 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6401 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6402 } 6403 6404 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6405 G1CollectedHeap* _g1h; 6406 6407 public: 6408 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6409 _g1h(g1h) {} 6410 6411 void do_code_blob(CodeBlob* cb) { 6412 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6413 if (nm == NULL) { 6414 return; 6415 } 6416 6417 if (ScavengeRootsInCode) { 6418 _g1h->register_nmethod(nm); 6419 } 6420 } 6421 }; 6422 6423 void G1CollectedHeap::rebuild_strong_code_roots() { 6424 RebuildStrongCodeRootClosure blob_cl(this); 6425 CodeCache::blobs_do(&blob_cl); 6426 }