1 /* 2 * Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/metadataOnStackMark.hpp" 27 #include "classfile/stringTable.hpp" 28 #include "classfile/symbolTable.hpp" 29 #include "code/codeCache.hpp" 30 #include "code/icBuffer.hpp" 31 #include "gc/g1/bufferingOopClosure.hpp" 32 #include "gc/g1/concurrentG1Refine.hpp" 33 #include "gc/g1/concurrentG1RefineThread.hpp" 34 #include "gc/g1/concurrentMarkThread.inline.hpp" 35 #include "gc/g1/g1Allocator.inline.hpp" 36 #include "gc/g1/g1CollectedHeap.inline.hpp" 37 #include "gc/g1/g1CollectorPolicy.hpp" 38 #include "gc/g1/g1CollectorState.hpp" 39 #include "gc/g1/g1EvacStats.inline.hpp" 40 #include "gc/g1/g1GCPhaseTimes.hpp" 41 #include "gc/g1/g1HeapVerifier.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.inline.hpp" 62 #include "gc/shared/generationSpec.hpp" 63 #include "gc/shared/isGCActiveMark.hpp" 64 #include "gc/shared/referenceProcessor.inline.hpp" 65 #include "gc/shared/taskqueue.inline.hpp" 66 #include "logging/log.hpp" 67 #include "memory/allocation.hpp" 68 #include "memory/iterator.hpp" 69 #include "oops/oop.inline.hpp" 70 #include "runtime/atomic.inline.hpp" 71 #include "runtime/init.hpp" 72 #include "runtime/orderAccess.inline.hpp" 73 #include "runtime/vmThread.hpp" 74 #include "utilities/globalDefinitions.hpp" 75 #include "utilities/stack.inline.hpp" 76 77 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 78 79 // INVARIANTS/NOTES 80 // 81 // All allocation activity covered by the G1CollectedHeap interface is 82 // serialized by acquiring the HeapLock. This happens in mem_allocate 83 // and allocate_new_tlab, which are the "entry" points to the 84 // allocation code from the rest of the JVM. (Note that this does not 85 // apply to TLAB allocation, which is not part of this interface: it 86 // is done by clients of this interface.) 87 88 // Local to this file. 89 90 class RefineCardTableEntryClosure: public CardTableEntryClosure { 91 bool _concurrent; 92 public: 93 RefineCardTableEntryClosure() : _concurrent(true) { } 94 95 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 96 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 97 // This path is executed by the concurrent refine or mutator threads, 98 // concurrently, and so we do not care if card_ptr contains references 99 // that point into the collection set. 100 assert(!oops_into_cset, "should be"); 101 102 if (_concurrent && SuspendibleThreadSet::should_yield()) { 103 // Caller will actually yield. 104 return false; 105 } 106 // Otherwise, we finished successfully; return true. 107 return true; 108 } 109 110 void set_concurrent(bool b) { _concurrent = b; } 111 }; 112 113 114 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 115 private: 116 size_t _num_dirtied; 117 G1CollectedHeap* _g1h; 118 G1SATBCardTableLoggingModRefBS* _g1_bs; 119 120 HeapRegion* region_for_card(jbyte* card_ptr) const { 121 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr)); 122 } 123 124 bool will_become_free(HeapRegion* hr) const { 125 // A region will be freed by free_collection_set if the region is in the 126 // collection set and has not had an evacuation failure. 127 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 128 } 129 130 public: 131 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(), 132 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { } 133 134 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 135 HeapRegion* hr = region_for_card(card_ptr); 136 137 // Should only dirty cards in regions that won't be freed. 138 if (!will_become_free(hr)) { 139 *card_ptr = CardTableModRefBS::dirty_card_val(); 140 _num_dirtied++; 141 } 142 143 return true; 144 } 145 146 size_t num_dirtied() const { return _num_dirtied; } 147 }; 148 149 150 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 151 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 152 } 153 154 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 155 // The from card cache is not the memory that is actually committed. So we cannot 156 // take advantage of the zero_filled parameter. 157 reset_from_card_cache(start_idx, num_regions); 158 } 159 160 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 161 { 162 // Claim the right to put the region on the dirty cards region list 163 // by installing a self pointer. 164 HeapRegion* next = hr->get_next_dirty_cards_region(); 165 if (next == NULL) { 166 HeapRegion* res = (HeapRegion*) 167 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 168 NULL); 169 if (res == NULL) { 170 HeapRegion* head; 171 do { 172 // Put the region to the dirty cards region list. 173 head = _dirty_cards_region_list; 174 next = (HeapRegion*) 175 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 176 if (next == head) { 177 assert(hr->get_next_dirty_cards_region() == hr, 178 "hr->get_next_dirty_cards_region() != hr"); 179 if (next == NULL) { 180 // The last region in the list points to itself. 181 hr->set_next_dirty_cards_region(hr); 182 } else { 183 hr->set_next_dirty_cards_region(next); 184 } 185 } 186 } while (next != head); 187 } 188 } 189 } 190 191 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 192 { 193 HeapRegion* head; 194 HeapRegion* hr; 195 do { 196 head = _dirty_cards_region_list; 197 if (head == NULL) { 198 return NULL; 199 } 200 HeapRegion* new_head = head->get_next_dirty_cards_region(); 201 if (head == new_head) { 202 // The last region. 203 new_head = NULL; 204 } 205 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 206 head); 207 } while (hr != head); 208 assert(hr != NULL, "invariant"); 209 hr->set_next_dirty_cards_region(NULL); 210 return hr; 211 } 212 213 // Returns true if the reference points to an object that 214 // can move in an incremental collection. 215 bool G1CollectedHeap::is_scavengable(const void* p) { 216 HeapRegion* hr = heap_region_containing(p); 217 return !hr->is_pinned(); 218 } 219 220 // Private methods. 221 222 HeapRegion* 223 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 224 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 225 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 226 if (!_secondary_free_list.is_empty()) { 227 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 228 "secondary_free_list has %u entries", 229 _secondary_free_list.length()); 230 // It looks as if there are free regions available on the 231 // secondary_free_list. Let's move them to the free_list and try 232 // again to allocate from it. 233 append_secondary_free_list(); 234 235 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 236 "empty we should have moved at least one entry to the free_list"); 237 HeapRegion* res = _hrm.allocate_free_region(is_old); 238 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 239 "allocated " HR_FORMAT " from secondary_free_list", 240 HR_FORMAT_PARAMS(res)); 241 return res; 242 } 243 244 // Wait here until we get notified either when (a) there are no 245 // more free regions coming or (b) some regions have been moved on 246 // the secondary_free_list. 247 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 248 } 249 250 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 251 "could not allocate from secondary_free_list"); 252 return NULL; 253 } 254 255 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 256 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 257 "the only time we use this to allocate a humongous region is " 258 "when we are allocating a single humongous region"); 259 260 HeapRegion* res; 261 if (G1StressConcRegionFreeing) { 262 if (!_secondary_free_list.is_empty()) { 263 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 264 "forced to look at the secondary_free_list"); 265 res = new_region_try_secondary_free_list(is_old); 266 if (res != NULL) { 267 return res; 268 } 269 } 270 } 271 272 res = _hrm.allocate_free_region(is_old); 273 274 if (res == NULL) { 275 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : " 276 "res == NULL, trying the secondary_free_list"); 277 res = new_region_try_secondary_free_list(is_old); 278 } 279 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 280 // Currently, only attempts to allocate GC alloc regions set 281 // do_expand to true. So, we should only reach here during a 282 // safepoint. If this assumption changes we might have to 283 // reconsider the use of _expand_heap_after_alloc_failure. 284 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 285 286 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 287 word_size * HeapWordSize); 288 289 if (expand(word_size * HeapWordSize)) { 290 // Given that expand() succeeded in expanding the heap, and we 291 // always expand the heap by an amount aligned to the heap 292 // region size, the free list should in theory not be empty. 293 // In either case allocate_free_region() will check for NULL. 294 res = _hrm.allocate_free_region(is_old); 295 } else { 296 _expand_heap_after_alloc_failure = false; 297 } 298 } 299 return res; 300 } 301 302 HeapWord* 303 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 304 uint num_regions, 305 size_t word_size, 306 AllocationContext_t context) { 307 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 308 assert(is_humongous(word_size), "word_size should be humongous"); 309 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 310 311 // Index of last region in the series. 312 uint last = first + num_regions - 1; 313 314 // We need to initialize the region(s) we just discovered. This is 315 // a bit tricky given that it can happen concurrently with 316 // refinement threads refining cards on these regions and 317 // potentially wanting to refine the BOT as they are scanning 318 // those cards (this can happen shortly after a cleanup; see CR 319 // 6991377). So we have to set up the region(s) carefully and in 320 // a specific order. 321 322 // The word size sum of all the regions we will allocate. 323 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 324 assert(word_size <= word_size_sum, "sanity"); 325 326 // This will be the "starts humongous" region. 327 HeapRegion* first_hr = region_at(first); 328 // The header of the new object will be placed at the bottom of 329 // the first region. 330 HeapWord* new_obj = first_hr->bottom(); 331 // This will be the new top of the new object. 332 HeapWord* obj_top = new_obj + word_size; 333 334 // First, we need to zero the header of the space that we will be 335 // allocating. When we update top further down, some refinement 336 // threads might try to scan the region. By zeroing the header we 337 // ensure that any thread that will try to scan the region will 338 // come across the zero klass word and bail out. 339 // 340 // NOTE: It would not have been correct to have used 341 // CollectedHeap::fill_with_object() and make the space look like 342 // an int array. The thread that is doing the allocation will 343 // later update the object header to a potentially different array 344 // type and, for a very short period of time, the klass and length 345 // fields will be inconsistent. This could cause a refinement 346 // thread to calculate the object size incorrectly. 347 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 348 349 // How many words we use for filler objects. 350 size_t word_fill_size = word_size_sum - word_size; 351 352 // How many words memory we "waste" which cannot hold a filler object. 353 size_t words_not_fillable = 0; 354 355 if (word_fill_size >= min_fill_size()) { 356 fill_with_objects(obj_top, word_fill_size); 357 } else if (word_fill_size > 0) { 358 // We have space to fill, but we cannot fit an object there. 359 words_not_fillable = word_fill_size; 360 word_fill_size = 0; 361 } 362 363 // We will set up the first region as "starts humongous". This 364 // will also update the BOT covering all the regions to reflect 365 // that there is a single object that starts at the bottom of the 366 // first region. 367 first_hr->set_starts_humongous(obj_top, word_fill_size); 368 first_hr->set_allocation_context(context); 369 // Then, if there are any, we will set up the "continues 370 // humongous" regions. 371 HeapRegion* hr = NULL; 372 for (uint i = first + 1; i <= last; ++i) { 373 hr = region_at(i); 374 hr->set_continues_humongous(first_hr); 375 hr->set_allocation_context(context); 376 } 377 378 // Up to this point no concurrent thread would have been able to 379 // do any scanning on any region in this series. All the top 380 // fields still point to bottom, so the intersection between 381 // [bottom,top] and [card_start,card_end] will be empty. Before we 382 // update the top fields, we'll do a storestore to make sure that 383 // no thread sees the update to top before the zeroing of the 384 // object header and the BOT initialization. 385 OrderAccess::storestore(); 386 387 // Now, we will update the top fields of the "continues humongous" 388 // regions except the last one. 389 for (uint i = first; i < last; ++i) { 390 hr = region_at(i); 391 hr->set_top(hr->end()); 392 } 393 394 hr = region_at(last); 395 // If we cannot fit a filler object, we must set top to the end 396 // of the humongous object, otherwise we cannot iterate the heap 397 // and the BOT will not be complete. 398 hr->set_top(hr->end() - words_not_fillable); 399 400 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 401 "obj_top should be in last region"); 402 403 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 404 405 assert(words_not_fillable == 0 || 406 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 407 "Miscalculation in humongous allocation"); 408 409 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 410 411 for (uint i = first; i <= last; ++i) { 412 hr = region_at(i); 413 _humongous_set.add(hr); 414 _hr_printer.alloc(hr); 415 } 416 417 return new_obj; 418 } 419 420 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 421 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 422 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 423 } 424 425 // If could fit into free regions w/o expansion, try. 426 // Otherwise, if can expand, do so. 427 // Otherwise, if using ex regions might help, try with ex given back. 428 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 429 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 430 431 _verifier->verify_region_sets_optional(); 432 433 uint first = G1_NO_HRM_INDEX; 434 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 435 436 if (obj_regions == 1) { 437 // Only one region to allocate, try to use a fast path by directly allocating 438 // from the free lists. Do not try to expand here, we will potentially do that 439 // later. 440 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 441 if (hr != NULL) { 442 first = hr->hrm_index(); 443 } 444 } else { 445 // We can't allocate humongous regions spanning more than one region while 446 // cleanupComplete() is running, since some of the regions we find to be 447 // empty might not yet be added to the free list. It is not straightforward 448 // to know in which list they are on so that we can remove them. We only 449 // need to do this if we need to allocate more than one region to satisfy the 450 // current humongous allocation request. If we are only allocating one region 451 // we use the one-region region allocation code (see above), that already 452 // potentially waits for regions from the secondary free list. 453 wait_while_free_regions_coming(); 454 append_secondary_free_list_if_not_empty_with_lock(); 455 456 // Policy: Try only empty regions (i.e. already committed first). Maybe we 457 // are lucky enough to find some. 458 first = _hrm.find_contiguous_only_empty(obj_regions); 459 if (first != G1_NO_HRM_INDEX) { 460 _hrm.allocate_free_regions_starting_at(first, obj_regions); 461 } 462 } 463 464 if (first == G1_NO_HRM_INDEX) { 465 // Policy: We could not find enough regions for the humongous object in the 466 // free list. Look through the heap to find a mix of free and uncommitted regions. 467 // If so, try expansion. 468 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 469 if (first != G1_NO_HRM_INDEX) { 470 // We found something. Make sure these regions are committed, i.e. expand 471 // the heap. Alternatively we could do a defragmentation GC. 472 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", 473 word_size * HeapWordSize); 474 475 476 _hrm.expand_at(first, obj_regions); 477 g1_policy()->record_new_heap_size(num_regions()); 478 479 #ifdef ASSERT 480 for (uint i = first; i < first + obj_regions; ++i) { 481 HeapRegion* hr = region_at(i); 482 assert(hr->is_free(), "sanity"); 483 assert(hr->is_empty(), "sanity"); 484 assert(is_on_master_free_list(hr), "sanity"); 485 } 486 #endif 487 _hrm.allocate_free_regions_starting_at(first, obj_regions); 488 } else { 489 // Policy: Potentially trigger a defragmentation GC. 490 } 491 } 492 493 HeapWord* result = NULL; 494 if (first != G1_NO_HRM_INDEX) { 495 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 496 word_size, context); 497 assert(result != NULL, "it should always return a valid result"); 498 499 // A successful humongous object allocation changes the used space 500 // information of the old generation so we need to recalculate the 501 // sizes and update the jstat counters here. 502 g1mm()->update_sizes(); 503 } 504 505 _verifier->verify_region_sets_optional(); 506 507 return result; 508 } 509 510 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 511 assert_heap_not_locked_and_not_at_safepoint(); 512 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 513 514 uint dummy_gc_count_before; 515 uint dummy_gclocker_retry_count = 0; 516 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 517 } 518 519 HeapWord* 520 G1CollectedHeap::mem_allocate(size_t word_size, 521 bool* gc_overhead_limit_was_exceeded) { 522 assert_heap_not_locked_and_not_at_safepoint(); 523 524 // Loop until the allocation is satisfied, or unsatisfied after GC. 525 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 526 uint gc_count_before; 527 528 HeapWord* result = NULL; 529 if (!is_humongous(word_size)) { 530 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 531 } else { 532 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 533 } 534 if (result != NULL) { 535 return result; 536 } 537 538 // Create the garbage collection operation... 539 VM_G1CollectForAllocation op(gc_count_before, word_size); 540 op.set_allocation_context(AllocationContext::current()); 541 542 // ...and get the VM thread to execute it. 543 VMThread::execute(&op); 544 545 if (op.prologue_succeeded() && op.pause_succeeded()) { 546 // If the operation was successful we'll return the result even 547 // if it is NULL. If the allocation attempt failed immediately 548 // after a Full GC, it's unlikely we'll be able to allocate now. 549 HeapWord* result = op.result(); 550 if (result != NULL && !is_humongous(word_size)) { 551 // Allocations that take place on VM operations do not do any 552 // card dirtying and we have to do it here. We only have to do 553 // this for non-humongous allocations, though. 554 dirty_young_block(result, word_size); 555 } 556 return result; 557 } else { 558 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 559 return NULL; 560 } 561 assert(op.result() == NULL, 562 "the result should be NULL if the VM op did not succeed"); 563 } 564 565 // Give a warning if we seem to be looping forever. 566 if ((QueuedAllocationWarningCount > 0) && 567 (try_count % QueuedAllocationWarningCount == 0)) { 568 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 569 } 570 } 571 572 ShouldNotReachHere(); 573 return NULL; 574 } 575 576 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 577 AllocationContext_t context, 578 uint* gc_count_before_ret, 579 uint* gclocker_retry_count_ret) { 580 // Make sure you read the note in attempt_allocation_humongous(). 581 582 assert_heap_not_locked_and_not_at_safepoint(); 583 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 584 "be called for humongous allocation requests"); 585 586 // We should only get here after the first-level allocation attempt 587 // (attempt_allocation()) failed to allocate. 588 589 // We will loop until a) we manage to successfully perform the 590 // allocation or b) we successfully schedule a collection which 591 // fails to perform the allocation. b) is the only case when we'll 592 // return NULL. 593 HeapWord* result = NULL; 594 for (int try_count = 1; /* we'll return */; try_count += 1) { 595 bool should_try_gc; 596 uint gc_count_before; 597 598 { 599 MutexLockerEx x(Heap_lock); 600 result = _allocator->attempt_allocation_locked(word_size, context); 601 if (result != NULL) { 602 return result; 603 } 604 605 if (GCLocker::is_active_and_needs_gc()) { 606 if (g1_policy()->can_expand_young_list()) { 607 // No need for an ergo verbose message here, 608 // can_expand_young_list() does this when it returns true. 609 result = _allocator->attempt_allocation_force(word_size, context); 610 if (result != NULL) { 611 return result; 612 } 613 } 614 should_try_gc = false; 615 } else { 616 // The GCLocker may not be active but the GCLocker initiated 617 // GC may not yet have been performed (GCLocker::needs_gc() 618 // returns true). In this case we do not try this GC and 619 // wait until the GCLocker initiated GC is performed, and 620 // then retry the allocation. 621 if (GCLocker::needs_gc()) { 622 should_try_gc = false; 623 } else { 624 // Read the GC count while still holding the Heap_lock. 625 gc_count_before = total_collections(); 626 should_try_gc = true; 627 } 628 } 629 } 630 631 if (should_try_gc) { 632 bool succeeded; 633 result = do_collection_pause(word_size, gc_count_before, &succeeded, 634 GCCause::_g1_inc_collection_pause); 635 if (result != NULL) { 636 assert(succeeded, "only way to get back a non-NULL result"); 637 return result; 638 } 639 640 if (succeeded) { 641 // If we get here we successfully scheduled a collection which 642 // failed to allocate. No point in trying to allocate 643 // further. We'll just return NULL. 644 MutexLockerEx x(Heap_lock); 645 *gc_count_before_ret = total_collections(); 646 return NULL; 647 } 648 } else { 649 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 650 MutexLockerEx x(Heap_lock); 651 *gc_count_before_ret = total_collections(); 652 return NULL; 653 } 654 // The GCLocker is either active or the GCLocker initiated 655 // GC has not yet been performed. Stall until it is and 656 // then retry the allocation. 657 GCLocker::stall_until_clear(); 658 (*gclocker_retry_count_ret) += 1; 659 } 660 661 // We can reach here if we were unsuccessful in scheduling a 662 // collection (because another thread beat us to it) or if we were 663 // stalled due to the GC locker. In either can we should retry the 664 // allocation attempt in case another thread successfully 665 // performed a collection and reclaimed enough space. We do the 666 // first attempt (without holding the Heap_lock) here and the 667 // follow-on attempt will be at the start of the next loop 668 // iteration (after taking the Heap_lock). 669 result = _allocator->attempt_allocation(word_size, context); 670 if (result != NULL) { 671 return result; 672 } 673 674 // Give a warning if we seem to be looping forever. 675 if ((QueuedAllocationWarningCount > 0) && 676 (try_count % QueuedAllocationWarningCount == 0)) { 677 warning("G1CollectedHeap::attempt_allocation_slow() " 678 "retries %d times", try_count); 679 } 680 } 681 682 ShouldNotReachHere(); 683 return NULL; 684 } 685 686 void G1CollectedHeap::begin_archive_alloc_range() { 687 assert_at_safepoint(true /* should_be_vm_thread */); 688 if (_archive_allocator == NULL) { 689 _archive_allocator = G1ArchiveAllocator::create_allocator(this); 690 } 691 } 692 693 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 694 // Allocations in archive regions cannot be of a size that would be considered 695 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 696 // may be different at archive-restore time. 697 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 698 } 699 700 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 701 assert_at_safepoint(true /* should_be_vm_thread */); 702 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 703 if (is_archive_alloc_too_large(word_size)) { 704 return NULL; 705 } 706 return _archive_allocator->archive_mem_allocate(word_size); 707 } 708 709 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 710 size_t end_alignment_in_bytes) { 711 assert_at_safepoint(true /* should_be_vm_thread */); 712 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 713 714 // Call complete_archive to do the real work, filling in the MemRegion 715 // array with the archive regions. 716 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 717 delete _archive_allocator; 718 _archive_allocator = NULL; 719 } 720 721 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 722 assert(ranges != NULL, "MemRegion array NULL"); 723 assert(count != 0, "No MemRegions provided"); 724 MemRegion reserved = _hrm.reserved(); 725 for (size_t i = 0; i < count; i++) { 726 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 727 return false; 728 } 729 } 730 return true; 731 } 732 733 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) { 734 assert(!is_init_completed(), "Expect to be called at JVM init time"); 735 assert(ranges != NULL, "MemRegion array NULL"); 736 assert(count != 0, "No MemRegions provided"); 737 MutexLockerEx x(Heap_lock); 738 739 MemRegion reserved = _hrm.reserved(); 740 HeapWord* prev_last_addr = NULL; 741 HeapRegion* prev_last_region = NULL; 742 743 // Temporarily disable pretouching of heap pages. This interface is used 744 // when mmap'ing archived heap data in, so pre-touching is wasted. 745 FlagSetting fs(AlwaysPreTouch, false); 746 747 // Enable archive object checking in G1MarkSweep. We have to let it know 748 // about each archive range, so that objects in those ranges aren't marked. 749 G1MarkSweep::enable_archive_object_check(); 750 751 // For each specified MemRegion range, allocate the corresponding G1 752 // regions and mark them as archive regions. We expect the ranges in 753 // ascending starting address order, without overlap. 754 for (size_t i = 0; i < count; i++) { 755 MemRegion curr_range = ranges[i]; 756 HeapWord* start_address = curr_range.start(); 757 size_t word_size = curr_range.word_size(); 758 HeapWord* last_address = curr_range.last(); 759 size_t commits = 0; 760 761 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 762 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 763 p2i(start_address), p2i(last_address)); 764 guarantee(start_address > prev_last_addr, 765 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 766 p2i(start_address), p2i(prev_last_addr)); 767 prev_last_addr = last_address; 768 769 // Check for ranges that start in the same G1 region in which the previous 770 // range ended, and adjust the start address so we don't try to allocate 771 // the same region again. If the current range is entirely within that 772 // region, skip it, just adjusting the recorded top. 773 HeapRegion* start_region = _hrm.addr_to_region(start_address); 774 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 775 start_address = start_region->end(); 776 if (start_address > last_address) { 777 increase_used(word_size * HeapWordSize); 778 start_region->set_top(last_address + 1); 779 continue; 780 } 781 start_region->set_top(start_address); 782 curr_range = MemRegion(start_address, last_address + 1); 783 start_region = _hrm.addr_to_region(start_address); 784 } 785 786 // Perform the actual region allocation, exiting if it fails. 787 // Then note how much new space we have allocated. 788 if (!_hrm.allocate_containing_regions(curr_range, &commits)) { 789 return false; 790 } 791 increase_used(word_size * HeapWordSize); 792 if (commits != 0) { 793 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 794 HeapRegion::GrainWords * HeapWordSize * commits); 795 796 } 797 798 // Mark each G1 region touched by the range as archive, add it to the old set, 799 // and set the allocation context and top. 800 HeapRegion* curr_region = _hrm.addr_to_region(start_address); 801 HeapRegion* last_region = _hrm.addr_to_region(last_address); 802 prev_last_region = last_region; 803 804 while (curr_region != NULL) { 805 assert(curr_region->is_empty() && !curr_region->is_pinned(), 806 "Region already in use (index %u)", curr_region->hrm_index()); 807 curr_region->set_allocation_context(AllocationContext::system()); 808 curr_region->set_archive(); 809 _hr_printer.alloc(curr_region); 810 _old_set.add(curr_region); 811 if (curr_region != last_region) { 812 curr_region->set_top(curr_region->end()); 813 curr_region = _hrm.next_region_in_heap(curr_region); 814 } else { 815 curr_region->set_top(last_address + 1); 816 curr_region = NULL; 817 } 818 } 819 820 // Notify mark-sweep of the archive range. 821 G1MarkSweep::set_range_archive(curr_range, true); 822 } 823 return true; 824 } 825 826 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 827 assert(!is_init_completed(), "Expect to be called at JVM init time"); 828 assert(ranges != NULL, "MemRegion array NULL"); 829 assert(count != 0, "No MemRegions provided"); 830 MemRegion reserved = _hrm.reserved(); 831 HeapWord *prev_last_addr = NULL; 832 HeapRegion* prev_last_region = NULL; 833 834 // For each MemRegion, create filler objects, if needed, in the G1 regions 835 // that contain the address range. The address range actually within the 836 // MemRegion will not be modified. That is assumed to have been initialized 837 // elsewhere, probably via an mmap of archived heap data. 838 MutexLockerEx x(Heap_lock); 839 for (size_t i = 0; i < count; i++) { 840 HeapWord* start_address = ranges[i].start(); 841 HeapWord* last_address = ranges[i].last(); 842 843 assert(reserved.contains(start_address) && reserved.contains(last_address), 844 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 845 p2i(start_address), p2i(last_address)); 846 assert(start_address > prev_last_addr, 847 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 848 p2i(start_address), p2i(prev_last_addr)); 849 850 HeapRegion* start_region = _hrm.addr_to_region(start_address); 851 HeapRegion* last_region = _hrm.addr_to_region(last_address); 852 HeapWord* bottom_address = start_region->bottom(); 853 854 // Check for a range beginning in the same region in which the 855 // previous one ended. 856 if (start_region == prev_last_region) { 857 bottom_address = prev_last_addr + 1; 858 } 859 860 // Verify that the regions were all marked as archive regions by 861 // alloc_archive_regions. 862 HeapRegion* curr_region = start_region; 863 while (curr_region != NULL) { 864 guarantee(curr_region->is_archive(), 865 "Expected archive region at index %u", curr_region->hrm_index()); 866 if (curr_region != last_region) { 867 curr_region = _hrm.next_region_in_heap(curr_region); 868 } else { 869 curr_region = NULL; 870 } 871 } 872 873 prev_last_addr = last_address; 874 prev_last_region = last_region; 875 876 // Fill the memory below the allocated range with dummy object(s), 877 // if the region bottom does not match the range start, or if the previous 878 // range ended within the same G1 region, and there is a gap. 879 if (start_address != bottom_address) { 880 size_t fill_size = pointer_delta(start_address, bottom_address); 881 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 882 increase_used(fill_size * HeapWordSize); 883 } 884 } 885 } 886 887 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size, 888 uint* gc_count_before_ret, 889 uint* gclocker_retry_count_ret) { 890 assert_heap_not_locked_and_not_at_safepoint(); 891 assert(!is_humongous(word_size), "attempt_allocation() should not " 892 "be called for humongous allocation requests"); 893 894 AllocationContext_t context = AllocationContext::current(); 895 HeapWord* result = _allocator->attempt_allocation(word_size, context); 896 897 if (result == NULL) { 898 result = attempt_allocation_slow(word_size, 899 context, 900 gc_count_before_ret, 901 gclocker_retry_count_ret); 902 } 903 assert_heap_not_locked(); 904 if (result != NULL) { 905 dirty_young_block(result, word_size); 906 } 907 return result; 908 } 909 910 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 911 assert(!is_init_completed(), "Expect to be called at JVM init time"); 912 assert(ranges != NULL, "MemRegion array NULL"); 913 assert(count != 0, "No MemRegions provided"); 914 MemRegion reserved = _hrm.reserved(); 915 HeapWord* prev_last_addr = NULL; 916 HeapRegion* prev_last_region = NULL; 917 size_t size_used = 0; 918 size_t uncommitted_regions = 0; 919 920 // For each Memregion, free the G1 regions that constitute it, and 921 // notify mark-sweep that the range is no longer to be considered 'archive.' 922 MutexLockerEx x(Heap_lock); 923 for (size_t i = 0; i < count; i++) { 924 HeapWord* start_address = ranges[i].start(); 925 HeapWord* last_address = ranges[i].last(); 926 927 assert(reserved.contains(start_address) && reserved.contains(last_address), 928 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 929 p2i(start_address), p2i(last_address)); 930 assert(start_address > prev_last_addr, 931 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 932 p2i(start_address), p2i(prev_last_addr)); 933 size_used += ranges[i].byte_size(); 934 prev_last_addr = last_address; 935 936 HeapRegion* start_region = _hrm.addr_to_region(start_address); 937 HeapRegion* last_region = _hrm.addr_to_region(last_address); 938 939 // Check for ranges that start in the same G1 region in which the previous 940 // range ended, and adjust the start address so we don't try to free 941 // the same region again. If the current range is entirely within that 942 // region, skip it. 943 if (start_region == prev_last_region) { 944 start_address = start_region->end(); 945 if (start_address > last_address) { 946 continue; 947 } 948 start_region = _hrm.addr_to_region(start_address); 949 } 950 prev_last_region = last_region; 951 952 // After verifying that each region was marked as an archive region by 953 // alloc_archive_regions, set it free and empty and uncommit it. 954 HeapRegion* curr_region = start_region; 955 while (curr_region != NULL) { 956 guarantee(curr_region->is_archive(), 957 "Expected archive region at index %u", curr_region->hrm_index()); 958 uint curr_index = curr_region->hrm_index(); 959 _old_set.remove(curr_region); 960 curr_region->set_free(); 961 curr_region->set_top(curr_region->bottom()); 962 if (curr_region != last_region) { 963 curr_region = _hrm.next_region_in_heap(curr_region); 964 } else { 965 curr_region = NULL; 966 } 967 _hrm.shrink_at(curr_index, 1); 968 uncommitted_regions++; 969 } 970 971 // Notify mark-sweep that this is no longer an archive range. 972 G1MarkSweep::set_range_archive(ranges[i], false); 973 } 974 975 if (uncommitted_regions != 0) { 976 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 977 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 978 } 979 decrease_used(size_used); 980 } 981 982 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 983 uint* gc_count_before_ret, 984 uint* gclocker_retry_count_ret) { 985 // The structure of this method has a lot of similarities to 986 // attempt_allocation_slow(). The reason these two were not merged 987 // into a single one is that such a method would require several "if 988 // allocation is not humongous do this, otherwise do that" 989 // conditional paths which would obscure its flow. In fact, an early 990 // version of this code did use a unified method which was harder to 991 // follow and, as a result, it had subtle bugs that were hard to 992 // track down. So keeping these two methods separate allows each to 993 // be more readable. It will be good to keep these two in sync as 994 // much as possible. 995 996 assert_heap_not_locked_and_not_at_safepoint(); 997 assert(is_humongous(word_size), "attempt_allocation_humongous() " 998 "should only be called for humongous allocations"); 999 1000 // Humongous objects can exhaust the heap quickly, so we should check if we 1001 // need to start a marking cycle at each humongous object allocation. We do 1002 // the check before we do the actual allocation. The reason for doing it 1003 // before the allocation is that we avoid having to keep track of the newly 1004 // allocated memory while we do a GC. 1005 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1006 word_size)) { 1007 collect(GCCause::_g1_humongous_allocation); 1008 } 1009 1010 // We will loop until a) we manage to successfully perform the 1011 // allocation or b) we successfully schedule a collection which 1012 // fails to perform the allocation. b) is the only case when we'll 1013 // return NULL. 1014 HeapWord* result = NULL; 1015 for (int try_count = 1; /* we'll return */; try_count += 1) { 1016 bool should_try_gc; 1017 uint gc_count_before; 1018 1019 { 1020 MutexLockerEx x(Heap_lock); 1021 1022 // Given that humongous objects are not allocated in young 1023 // regions, we'll first try to do the allocation without doing a 1024 // collection hoping that there's enough space in the heap. 1025 result = humongous_obj_allocate(word_size, AllocationContext::current()); 1026 if (result != NULL) { 1027 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 1028 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 1029 return result; 1030 } 1031 1032 if (GCLocker::is_active_and_needs_gc()) { 1033 should_try_gc = false; 1034 } else { 1035 // The GCLocker may not be active but the GCLocker initiated 1036 // GC may not yet have been performed (GCLocker::needs_gc() 1037 // returns true). In this case we do not try this GC and 1038 // wait until the GCLocker initiated GC is performed, and 1039 // then retry the allocation. 1040 if (GCLocker::needs_gc()) { 1041 should_try_gc = false; 1042 } else { 1043 // Read the GC count while still holding the Heap_lock. 1044 gc_count_before = total_collections(); 1045 should_try_gc = true; 1046 } 1047 } 1048 } 1049 1050 if (should_try_gc) { 1051 // If we failed to allocate the humongous object, we should try to 1052 // do a collection pause (if we're allowed) in case it reclaims 1053 // enough space for the allocation to succeed after the pause. 1054 1055 bool succeeded; 1056 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1057 GCCause::_g1_humongous_allocation); 1058 if (result != NULL) { 1059 assert(succeeded, "only way to get back a non-NULL result"); 1060 return result; 1061 } 1062 1063 if (succeeded) { 1064 // If we get here we successfully scheduled a collection which 1065 // failed to allocate. No point in trying to allocate 1066 // further. We'll just return NULL. 1067 MutexLockerEx x(Heap_lock); 1068 *gc_count_before_ret = total_collections(); 1069 return NULL; 1070 } 1071 } else { 1072 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1073 MutexLockerEx x(Heap_lock); 1074 *gc_count_before_ret = total_collections(); 1075 return NULL; 1076 } 1077 // The GCLocker is either active or the GCLocker initiated 1078 // GC has not yet been performed. Stall until it is and 1079 // then retry the allocation. 1080 GCLocker::stall_until_clear(); 1081 (*gclocker_retry_count_ret) += 1; 1082 } 1083 1084 // We can reach here if we were unsuccessful in scheduling a 1085 // collection (because another thread beat us to it) or if we were 1086 // stalled due to the GC locker. In either can we should retry the 1087 // allocation attempt in case another thread successfully 1088 // performed a collection and reclaimed enough space. Give a 1089 // warning if we seem to be looping forever. 1090 1091 if ((QueuedAllocationWarningCount > 0) && 1092 (try_count % QueuedAllocationWarningCount == 0)) { 1093 warning("G1CollectedHeap::attempt_allocation_humongous() " 1094 "retries %d times", try_count); 1095 } 1096 } 1097 1098 ShouldNotReachHere(); 1099 return NULL; 1100 } 1101 1102 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1103 AllocationContext_t context, 1104 bool expect_null_mutator_alloc_region) { 1105 assert_at_safepoint(true /* should_be_vm_thread */); 1106 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region, 1107 "the current alloc region was unexpectedly found to be non-NULL"); 1108 1109 if (!is_humongous(word_size)) { 1110 return _allocator->attempt_allocation_locked(word_size, context); 1111 } else { 1112 HeapWord* result = humongous_obj_allocate(word_size, context); 1113 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1114 collector_state()->set_initiate_conc_mark_if_possible(true); 1115 } 1116 return result; 1117 } 1118 1119 ShouldNotReachHere(); 1120 } 1121 1122 class PostMCRemSetClearClosure: public HeapRegionClosure { 1123 G1CollectedHeap* _g1h; 1124 ModRefBarrierSet* _mr_bs; 1125 public: 1126 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1127 _g1h(g1h), _mr_bs(mr_bs) {} 1128 1129 bool doHeapRegion(HeapRegion* r) { 1130 HeapRegionRemSet* hrrs = r->rem_set(); 1131 1132 _g1h->reset_gc_time_stamps(r); 1133 1134 if (r->is_continues_humongous()) { 1135 // We'll assert that the strong code root list and RSet is empty 1136 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1137 assert(hrrs->occupied() == 0, "RSet should be empty"); 1138 } else { 1139 hrrs->clear(); 1140 } 1141 // You might think here that we could clear just the cards 1142 // corresponding to the used region. But no: if we leave a dirty card 1143 // in a region we might allocate into, then it would prevent that card 1144 // from being enqueued, and cause it to be missed. 1145 // Re: the performance cost: we shouldn't be doing full GC anyway! 1146 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1147 1148 return false; 1149 } 1150 }; 1151 1152 void G1CollectedHeap::clear_rsets_post_compaction() { 1153 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1154 heap_region_iterate(&rs_clear); 1155 } 1156 1157 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1158 G1CollectedHeap* _g1h; 1159 UpdateRSOopClosure _cl; 1160 public: 1161 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) : 1162 _cl(g1->g1_rem_set(), worker_i), 1163 _g1h(g1) 1164 { } 1165 1166 bool doHeapRegion(HeapRegion* r) { 1167 if (!r->is_continues_humongous()) { 1168 _cl.set_from(r); 1169 r->oop_iterate(&_cl); 1170 } 1171 return false; 1172 } 1173 }; 1174 1175 class ParRebuildRSTask: public AbstractGangTask { 1176 G1CollectedHeap* _g1; 1177 HeapRegionClaimer _hrclaimer; 1178 1179 public: 1180 ParRebuildRSTask(G1CollectedHeap* g1) : 1181 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {} 1182 1183 void work(uint worker_id) { 1184 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1185 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer); 1186 } 1187 }; 1188 1189 class PostCompactionPrinterClosure: public HeapRegionClosure { 1190 private: 1191 G1HRPrinter* _hr_printer; 1192 public: 1193 bool doHeapRegion(HeapRegion* hr) { 1194 assert(!hr->is_young(), "not expecting to find young regions"); 1195 _hr_printer->post_compaction(hr); 1196 return false; 1197 } 1198 1199 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1200 : _hr_printer(hr_printer) { } 1201 }; 1202 1203 void G1CollectedHeap::print_hrm_post_compaction() { 1204 if (_hr_printer.is_active()) { 1205 PostCompactionPrinterClosure cl(hr_printer()); 1206 heap_region_iterate(&cl); 1207 } 1208 1209 } 1210 1211 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1212 bool clear_all_soft_refs) { 1213 assert_at_safepoint(true /* should_be_vm_thread */); 1214 1215 if (GCLocker::check_active_before_gc()) { 1216 return false; 1217 } 1218 1219 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1220 gc_timer->register_gc_start(); 1221 1222 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1223 GCIdMark gc_id_mark; 1224 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1225 1226 SvcGCMarker sgcm(SvcGCMarker::FULL); 1227 ResourceMark rm; 1228 1229 print_heap_before_gc(); 1230 trace_heap_before_gc(gc_tracer); 1231 1232 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1233 1234 _verifier->verify_region_sets_optional(); 1235 1236 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1237 collector_policy()->should_clear_all_soft_refs(); 1238 1239 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1240 1241 { 1242 IsGCActiveMark x; 1243 1244 // Timing 1245 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1246 GCTraceCPUTime tcpu; 1247 1248 { 1249 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1250 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1251 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1252 1253 g1_policy()->record_full_collection_start(); 1254 1255 // Note: When we have a more flexible GC logging framework that 1256 // allows us to add optional attributes to a GC log record we 1257 // could consider timing and reporting how long we wait in the 1258 // following two methods. 1259 wait_while_free_regions_coming(); 1260 // If we start the compaction before the CM threads finish 1261 // scanning the root regions we might trip them over as we'll 1262 // be moving objects / updating references. So let's wait until 1263 // they are done. By telling them to abort, they should complete 1264 // early. 1265 _cm->root_regions()->abort(); 1266 _cm->root_regions()->wait_until_scan_finished(); 1267 append_secondary_free_list_if_not_empty_with_lock(); 1268 1269 gc_prologue(true); 1270 increment_total_collections(true /* full gc */); 1271 increment_old_marking_cycles_started(); 1272 1273 assert(used() == recalculate_used(), "Should be equal"); 1274 1275 _verifier->verify_before_gc(); 1276 1277 _verifier->check_bitmaps("Full GC Start"); 1278 pre_full_gc_dump(gc_timer); 1279 1280 #if defined(COMPILER2) || INCLUDE_JVMCI 1281 DerivedPointerTable::clear(); 1282 #endif 1283 1284 // Disable discovery and empty the discovered lists 1285 // for the CM ref processor. 1286 ref_processor_cm()->disable_discovery(); 1287 ref_processor_cm()->abandon_partial_discovery(); 1288 ref_processor_cm()->verify_no_references_recorded(); 1289 1290 // Abandon current iterations of concurrent marking and concurrent 1291 // refinement, if any are in progress. We have to do this before 1292 // wait_until_scan_finished() below. 1293 concurrent_mark()->abort(); 1294 1295 // Make sure we'll choose a new allocation region afterwards. 1296 _allocator->release_mutator_alloc_region(); 1297 _allocator->abandon_gc_alloc_regions(); 1298 g1_rem_set()->cleanupHRRS(); 1299 1300 // We may have added regions to the current incremental collection 1301 // set between the last GC or pause and now. We need to clear the 1302 // incremental collection set and then start rebuilding it afresh 1303 // after this full GC. 1304 abandon_collection_set(g1_policy()->inc_cset_head()); 1305 g1_policy()->clear_incremental_cset(); 1306 g1_policy()->stop_incremental_cset_building(); 1307 1308 tear_down_region_sets(false /* free_list_only */); 1309 collector_state()->set_gcs_are_young(true); 1310 1311 // See the comments in g1CollectedHeap.hpp and 1312 // G1CollectedHeap::ref_processing_init() about 1313 // how reference processing currently works in G1. 1314 1315 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1316 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1317 1318 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1319 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1320 1321 ref_processor_stw()->enable_discovery(); 1322 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1323 1324 // Do collection work 1325 { 1326 HandleMark hm; // Discard invalid handles created during gc 1327 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1328 } 1329 1330 assert(num_free_regions() == 0, "we should not have added any free regions"); 1331 rebuild_region_sets(false /* free_list_only */); 1332 1333 // Enqueue any discovered reference objects that have 1334 // not been removed from the discovered lists. 1335 ref_processor_stw()->enqueue_discovered_references(); 1336 1337 #if defined(COMPILER2) || INCLUDE_JVMCI 1338 DerivedPointerTable::update_pointers(); 1339 #endif 1340 1341 MemoryService::track_memory_usage(); 1342 1343 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1344 ref_processor_stw()->verify_no_references_recorded(); 1345 1346 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1347 ClassLoaderDataGraph::purge(); 1348 MetaspaceAux::verify_metrics(); 1349 1350 // Note: since we've just done a full GC, concurrent 1351 // marking is no longer active. Therefore we need not 1352 // re-enable reference discovery for the CM ref processor. 1353 // That will be done at the start of the next marking cycle. 1354 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1355 ref_processor_cm()->verify_no_references_recorded(); 1356 1357 reset_gc_time_stamp(); 1358 // Since everything potentially moved, we will clear all remembered 1359 // sets, and clear all cards. Later we will rebuild remembered 1360 // sets. We will also reset the GC time stamps of the regions. 1361 clear_rsets_post_compaction(); 1362 check_gc_time_stamps(); 1363 1364 resize_if_necessary_after_full_collection(); 1365 1366 // We should do this after we potentially resize the heap so 1367 // that all the COMMIT / UNCOMMIT events are generated before 1368 // the compaction events. 1369 print_hrm_post_compaction(); 1370 1371 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1372 if (hot_card_cache->use_cache()) { 1373 hot_card_cache->reset_card_counts(); 1374 hot_card_cache->reset_hot_cache(); 1375 } 1376 1377 // Rebuild remembered sets of all regions. 1378 uint n_workers = 1379 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1380 workers()->active_workers(), 1381 Threads::number_of_non_daemon_threads()); 1382 workers()->set_active_workers(n_workers); 1383 1384 ParRebuildRSTask rebuild_rs_task(this); 1385 workers()->run_task(&rebuild_rs_task); 1386 1387 // Rebuild the strong code root lists for each region 1388 rebuild_strong_code_roots(); 1389 1390 if (true) { // FIXME 1391 MetaspaceGC::compute_new_size(); 1392 } 1393 1394 #ifdef TRACESPINNING 1395 ParallelTaskTerminator::print_termination_counts(); 1396 #endif 1397 1398 // Discard all rset updates 1399 JavaThread::dirty_card_queue_set().abandon_logs(); 1400 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1401 1402 _young_list->reset_sampled_info(); 1403 // At this point there should be no regions in the 1404 // entire heap tagged as young. 1405 assert(check_young_list_empty(true /* check_heap */), 1406 "young list should be empty at this point"); 1407 1408 // Update the number of full collections that have been completed. 1409 increment_old_marking_cycles_completed(false /* concurrent */); 1410 1411 _hrm.verify_optional(); 1412 _verifier->verify_region_sets_optional(); 1413 1414 _verifier->verify_after_gc(); 1415 1416 // Clear the previous marking bitmap, if needed for bitmap verification. 1417 // Note we cannot do this when we clear the next marking bitmap in 1418 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1419 // objects marked during a full GC against the previous bitmap. 1420 // But we need to clear it before calling check_bitmaps below since 1421 // the full GC has compacted objects and updated TAMS but not updated 1422 // the prev bitmap. 1423 if (G1VerifyBitmaps) { 1424 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1425 } 1426 _verifier->check_bitmaps("Full GC End"); 1427 1428 // Start a new incremental collection set for the next pause 1429 assert(g1_policy()->collection_set() == NULL, "must be"); 1430 g1_policy()->start_incremental_cset_building(); 1431 1432 clear_cset_fast_test(); 1433 1434 _allocator->init_mutator_alloc_region(); 1435 1436 g1_policy()->record_full_collection_end(); 1437 1438 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1439 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1440 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1441 // before any GC notifications are raised. 1442 g1mm()->update_sizes(); 1443 1444 gc_epilogue(true); 1445 } 1446 1447 g1_policy()->print_detailed_heap_transition(); 1448 1449 print_heap_after_gc(); 1450 trace_heap_after_gc(gc_tracer); 1451 1452 post_full_gc_dump(gc_timer); 1453 1454 gc_timer->register_gc_end(); 1455 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1456 } 1457 1458 return true; 1459 } 1460 1461 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1462 // Currently, there is no facility in the do_full_collection(bool) API to notify 1463 // the caller that the collection did not succeed (e.g., because it was locked 1464 // out by the GC locker). So, right now, we'll ignore the return value. 1465 bool dummy = do_full_collection(true, /* explicit_gc */ 1466 clear_all_soft_refs); 1467 } 1468 1469 void G1CollectedHeap::resize_if_necessary_after_full_collection() { 1470 // Include bytes that will be pre-allocated to support collections, as "used". 1471 const size_t used_after_gc = used(); 1472 const size_t capacity_after_gc = capacity(); 1473 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1474 1475 // This is enforced in arguments.cpp. 1476 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1477 "otherwise the code below doesn't make sense"); 1478 1479 // We don't have floating point command-line arguments 1480 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1481 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1482 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1483 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1484 1485 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1486 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1487 1488 // We have to be careful here as these two calculations can overflow 1489 // 32-bit size_t's. 1490 double used_after_gc_d = (double) used_after_gc; 1491 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1492 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1493 1494 // Let's make sure that they are both under the max heap size, which 1495 // by default will make them fit into a size_t. 1496 double desired_capacity_upper_bound = (double) max_heap_size; 1497 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1498 desired_capacity_upper_bound); 1499 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1500 desired_capacity_upper_bound); 1501 1502 // We can now safely turn them into size_t's. 1503 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1504 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1505 1506 // This assert only makes sense here, before we adjust them 1507 // with respect to the min and max heap size. 1508 assert(minimum_desired_capacity <= maximum_desired_capacity, 1509 "minimum_desired_capacity = " SIZE_FORMAT ", " 1510 "maximum_desired_capacity = " SIZE_FORMAT, 1511 minimum_desired_capacity, maximum_desired_capacity); 1512 1513 // Should not be greater than the heap max size. No need to adjust 1514 // it with respect to the heap min size as it's a lower bound (i.e., 1515 // we'll try to make the capacity larger than it, not smaller). 1516 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1517 // Should not be less than the heap min size. No need to adjust it 1518 // with respect to the heap max size as it's an upper bound (i.e., 1519 // we'll try to make the capacity smaller than it, not greater). 1520 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1521 1522 if (capacity_after_gc < minimum_desired_capacity) { 1523 // Don't expand unless it's significant 1524 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1525 1526 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). " 1527 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1528 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio); 1529 1530 expand(expand_bytes); 1531 1532 // No expansion, now see if we want to shrink 1533 } else if (capacity_after_gc > maximum_desired_capacity) { 1534 // Capacity too large, compute shrinking size 1535 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1536 1537 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). " 1538 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1539 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio); 1540 1541 shrink(shrink_bytes); 1542 } 1543 } 1544 1545 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1546 AllocationContext_t context, 1547 bool do_gc, 1548 bool clear_all_soft_refs, 1549 bool expect_null_mutator_alloc_region, 1550 bool* gc_succeeded) { 1551 *gc_succeeded = true; 1552 // Let's attempt the allocation first. 1553 HeapWord* result = 1554 attempt_allocation_at_safepoint(word_size, 1555 context, 1556 expect_null_mutator_alloc_region); 1557 if (result != NULL) { 1558 assert(*gc_succeeded, "sanity"); 1559 return result; 1560 } 1561 1562 // In a G1 heap, we're supposed to keep allocation from failing by 1563 // incremental pauses. Therefore, at least for now, we'll favor 1564 // expansion over collection. (This might change in the future if we can 1565 // do something smarter than full collection to satisfy a failed alloc.) 1566 result = expand_and_allocate(word_size, context); 1567 if (result != NULL) { 1568 assert(*gc_succeeded, "sanity"); 1569 return result; 1570 } 1571 1572 if (do_gc) { 1573 // Expansion didn't work, we'll try to do a Full GC. 1574 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1575 clear_all_soft_refs); 1576 } 1577 1578 return NULL; 1579 } 1580 1581 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1582 AllocationContext_t context, 1583 bool* succeeded) { 1584 assert_at_safepoint(true /* should_be_vm_thread */); 1585 1586 // Attempts to allocate followed by Full GC. 1587 HeapWord* result = 1588 satisfy_failed_allocation_helper(word_size, 1589 context, 1590 true, /* do_gc */ 1591 false, /* clear_all_soft_refs */ 1592 false, /* expect_null_mutator_alloc_region */ 1593 succeeded); 1594 1595 if (result != NULL || !*succeeded) { 1596 return result; 1597 } 1598 1599 // Attempts to allocate followed by Full GC that will collect all soft references. 1600 result = satisfy_failed_allocation_helper(word_size, 1601 context, 1602 true, /* do_gc */ 1603 true, /* clear_all_soft_refs */ 1604 true, /* expect_null_mutator_alloc_region */ 1605 succeeded); 1606 1607 if (result != NULL || !*succeeded) { 1608 return result; 1609 } 1610 1611 // Attempts to allocate, no GC 1612 result = satisfy_failed_allocation_helper(word_size, 1613 context, 1614 false, /* do_gc */ 1615 false, /* clear_all_soft_refs */ 1616 true, /* expect_null_mutator_alloc_region */ 1617 succeeded); 1618 1619 if (result != NULL) { 1620 assert(*succeeded, "sanity"); 1621 return result; 1622 } 1623 1624 assert(!collector_policy()->should_clear_all_soft_refs(), 1625 "Flag should have been handled and cleared prior to this point"); 1626 1627 // What else? We might try synchronous finalization later. If the total 1628 // space available is large enough for the allocation, then a more 1629 // complete compaction phase than we've tried so far might be 1630 // appropriate. 1631 assert(*succeeded, "sanity"); 1632 return NULL; 1633 } 1634 1635 // Attempting to expand the heap sufficiently 1636 // to support an allocation of the given "word_size". If 1637 // successful, perform the allocation and return the address of the 1638 // allocated block, or else "NULL". 1639 1640 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1641 assert_at_safepoint(true /* should_be_vm_thread */); 1642 1643 _verifier->verify_region_sets_optional(); 1644 1645 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1646 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1647 word_size * HeapWordSize); 1648 1649 1650 if (expand(expand_bytes)) { 1651 _hrm.verify_optional(); 1652 _verifier->verify_region_sets_optional(); 1653 return attempt_allocation_at_safepoint(word_size, 1654 context, 1655 false /* expect_null_mutator_alloc_region */); 1656 } 1657 return NULL; 1658 } 1659 1660 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) { 1661 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1662 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1663 HeapRegion::GrainBytes); 1664 1665 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B", 1666 expand_bytes, aligned_expand_bytes); 1667 1668 if (is_maximal_no_gc()) { 1669 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1670 return false; 1671 } 1672 1673 double expand_heap_start_time_sec = os::elapsedTime(); 1674 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1675 assert(regions_to_expand > 0, "Must expand by at least one region"); 1676 1677 uint expanded_by = _hrm.expand_by(regions_to_expand); 1678 if (expand_time_ms != NULL) { 1679 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1680 } 1681 1682 if (expanded_by > 0) { 1683 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1684 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1685 g1_policy()->record_new_heap_size(num_regions()); 1686 } else { 1687 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1688 1689 // The expansion of the virtual storage space was unsuccessful. 1690 // Let's see if it was because we ran out of swap. 1691 if (G1ExitOnExpansionFailure && 1692 _hrm.available() >= regions_to_expand) { 1693 // We had head room... 1694 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1695 } 1696 } 1697 return regions_to_expand > 0; 1698 } 1699 1700 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1701 size_t aligned_shrink_bytes = 1702 ReservedSpace::page_align_size_down(shrink_bytes); 1703 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1704 HeapRegion::GrainBytes); 1705 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1706 1707 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1708 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1709 1710 1711 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B", 1712 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1713 if (num_regions_removed > 0) { 1714 g1_policy()->record_new_heap_size(num_regions()); 1715 } else { 1716 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1717 } 1718 } 1719 1720 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1721 _verifier->verify_region_sets_optional(); 1722 1723 // We should only reach here at the end of a Full GC which means we 1724 // should not not be holding to any GC alloc regions. The method 1725 // below will make sure of that and do any remaining clean up. 1726 _allocator->abandon_gc_alloc_regions(); 1727 1728 // Instead of tearing down / rebuilding the free lists here, we 1729 // could instead use the remove_all_pending() method on free_list to 1730 // remove only the ones that we need to remove. 1731 tear_down_region_sets(true /* free_list_only */); 1732 shrink_helper(shrink_bytes); 1733 rebuild_region_sets(true /* free_list_only */); 1734 1735 _hrm.verify_optional(); 1736 _verifier->verify_region_sets_optional(); 1737 } 1738 1739 // Public methods. 1740 1741 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1742 CollectedHeap(), 1743 _g1_policy(policy_), 1744 _dirty_card_queue_set(false), 1745 _is_alive_closure_cm(this), 1746 _is_alive_closure_stw(this), 1747 _ref_processor_cm(NULL), 1748 _ref_processor_stw(NULL), 1749 _bot(NULL), 1750 _cg1r(NULL), 1751 _g1mm(NULL), 1752 _refine_cte_cl(NULL), 1753 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1754 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1755 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1756 _humongous_reclaim_candidates(), 1757 _has_humongous_reclaim_candidates(false), 1758 _archive_allocator(NULL), 1759 _free_regions_coming(false), 1760 _young_list(new YoungList(this)), 1761 _gc_time_stamp(0), 1762 _summary_bytes_used(0), 1763 _survivor_evac_stats(YoungPLABSize, PLABWeight), 1764 _old_evac_stats(OldPLABSize, PLABWeight), 1765 _expand_heap_after_alloc_failure(true), 1766 _old_marking_cycles_started(0), 1767 _old_marking_cycles_completed(0), 1768 _heap_summary_sent(false), 1769 _in_cset_fast_test(), 1770 _dirty_cards_region_list(NULL), 1771 _worker_cset_start_region(NULL), 1772 _worker_cset_start_region_time_stamp(NULL), 1773 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1774 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1775 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1776 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1777 1778 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1779 /* are_GC_task_threads */true, 1780 /* are_ConcurrentGC_threads */false); 1781 _workers->initialize_workers(); 1782 _verifier = new G1HeapVerifier(this); 1783 1784 _allocator = G1Allocator::create_allocator(this); 1785 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1786 1787 // Override the default _filler_array_max_size so that no humongous filler 1788 // objects are created. 1789 _filler_array_max_size = _humongous_object_threshold_in_words; 1790 1791 uint n_queues = ParallelGCThreads; 1792 _task_queues = new RefToScanQueueSet(n_queues); 1793 1794 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1795 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC); 1796 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1797 1798 for (uint i = 0; i < n_queues; i++) { 1799 RefToScanQueue* q = new RefToScanQueue(); 1800 q->initialize(); 1801 _task_queues->register_queue(i, q); 1802 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1803 } 1804 clear_cset_start_regions(); 1805 1806 // Initialize the G1EvacuationFailureALot counters and flags. 1807 NOT_PRODUCT(reset_evacuation_should_fail();) 1808 1809 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1810 } 1811 1812 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1813 size_t size, 1814 size_t translation_factor) { 1815 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1816 // Allocate a new reserved space, preferring to use large pages. 1817 ReservedSpace rs(size, preferred_page_size); 1818 G1RegionToSpaceMapper* result = 1819 G1RegionToSpaceMapper::create_mapper(rs, 1820 size, 1821 rs.alignment(), 1822 HeapRegion::GrainBytes, 1823 translation_factor, 1824 mtGC); 1825 if (TracePageSizes) { 1826 tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT, 1827 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size); 1828 } 1829 return result; 1830 } 1831 1832 jint G1CollectedHeap::initialize() { 1833 CollectedHeap::pre_initialize(); 1834 os::enable_vtime(); 1835 1836 // Necessary to satisfy locking discipline assertions. 1837 1838 MutexLocker x(Heap_lock); 1839 1840 // While there are no constraints in the GC code that HeapWordSize 1841 // be any particular value, there are multiple other areas in the 1842 // system which believe this to be true (e.g. oop->object_size in some 1843 // cases incorrectly returns the size in wordSize units rather than 1844 // HeapWordSize). 1845 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1846 1847 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1848 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1849 size_t heap_alignment = collector_policy()->heap_alignment(); 1850 1851 // Ensure that the sizes are properly aligned. 1852 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1853 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1854 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1855 1856 _refine_cte_cl = new RefineCardTableEntryClosure(); 1857 1858 jint ecode = JNI_OK; 1859 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode); 1860 if (_cg1r == NULL) { 1861 return ecode; 1862 } 1863 1864 // Reserve the maximum. 1865 1866 // When compressed oops are enabled, the preferred heap base 1867 // is calculated by subtracting the requested size from the 1868 // 32Gb boundary and using the result as the base address for 1869 // heap reservation. If the requested size is not aligned to 1870 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1871 // into the ReservedHeapSpace constructor) then the actual 1872 // base of the reserved heap may end up differing from the 1873 // address that was requested (i.e. the preferred heap base). 1874 // If this happens then we could end up using a non-optimal 1875 // compressed oops mode. 1876 1877 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1878 heap_alignment); 1879 1880 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1881 1882 // Create the barrier set for the entire reserved region. 1883 G1SATBCardTableLoggingModRefBS* bs 1884 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 1885 bs->initialize(); 1886 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 1887 set_barrier_set(bs); 1888 1889 // Also create a G1 rem set. 1890 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 1891 1892 // Carve out the G1 part of the heap. 1893 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1894 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 1895 G1RegionToSpaceMapper* heap_storage = 1896 G1RegionToSpaceMapper::create_mapper(g1_rs, 1897 g1_rs.size(), 1898 page_size, 1899 HeapRegion::GrainBytes, 1900 1, 1901 mtJavaHeap); 1902 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(), 1903 max_byte_size, page_size, 1904 heap_rs.base(), 1905 heap_rs.size()); 1906 heap_storage->set_mapping_changed_listener(&_listener); 1907 1908 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1909 G1RegionToSpaceMapper* bot_storage = 1910 create_aux_memory_mapper("Block offset table", 1911 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1912 G1BlockOffsetTable::heap_map_factor()); 1913 1914 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 1915 G1RegionToSpaceMapper* cardtable_storage = 1916 create_aux_memory_mapper("Card table", 1917 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize), 1918 G1SATBCardTableLoggingModRefBS::heap_map_factor()); 1919 1920 G1RegionToSpaceMapper* card_counts_storage = 1921 create_aux_memory_mapper("Card counts table", 1922 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1923 G1CardCounts::heap_map_factor()); 1924 1925 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); 1926 G1RegionToSpaceMapper* prev_bitmap_storage = 1927 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor()); 1928 G1RegionToSpaceMapper* next_bitmap_storage = 1929 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor()); 1930 1931 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1932 g1_barrier_set()->initialize(cardtable_storage); 1933 // Do later initialization work for concurrent refinement. 1934 _cg1r->init(card_counts_storage); 1935 1936 // 6843694 - ensure that the maximum region index can fit 1937 // in the remembered set structures. 1938 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1939 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1940 1941 G1RemSet::initialize(max_regions()); 1942 1943 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1944 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1945 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1946 "too many cards per region"); 1947 1948 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1949 1950 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1951 1952 { 1953 HeapWord* start = _hrm.reserved().start(); 1954 HeapWord* end = _hrm.reserved().end(); 1955 size_t granularity = HeapRegion::GrainBytes; 1956 1957 _in_cset_fast_test.initialize(start, end, granularity); 1958 _humongous_reclaim_candidates.initialize(start, end, granularity); 1959 } 1960 1961 // Create the ConcurrentMark data structure and thread. 1962 // (Must do this late, so that "max_regions" is defined.) 1963 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1964 if (_cm == NULL || !_cm->completed_initialization()) { 1965 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 1966 return JNI_ENOMEM; 1967 } 1968 _cmThread = _cm->cmThread(); 1969 1970 // Now expand into the initial heap size. 1971 if (!expand(init_byte_size)) { 1972 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1973 return JNI_ENOMEM; 1974 } 1975 1976 // Perform any initialization actions delegated to the policy. 1977 g1_policy()->init(); 1978 1979 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 1980 SATB_Q_FL_lock, 1981 G1SATBProcessCompletedThreshold, 1982 Shared_SATB_Q_lock); 1983 1984 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 1985 DirtyCardQ_CBL_mon, 1986 DirtyCardQ_FL_lock, 1987 concurrent_g1_refine()->yellow_zone(), 1988 concurrent_g1_refine()->red_zone(), 1989 Shared_DirtyCardQ_lock, 1990 NULL, // fl_owner 1991 true); // init_free_ids 1992 1993 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 1994 DirtyCardQ_CBL_mon, 1995 DirtyCardQ_FL_lock, 1996 -1, // never trigger processing 1997 -1, // no limit on length 1998 Shared_DirtyCardQ_lock, 1999 &JavaThread::dirty_card_queue_set()); 2000 2001 // Here we allocate the dummy HeapRegion that is required by the 2002 // G1AllocRegion class. 2003 HeapRegion* dummy_region = _hrm.get_dummy_region(); 2004 2005 // We'll re-use the same region whether the alloc region will 2006 // require BOT updates or not and, if it doesn't, then a non-young 2007 // region will complain that it cannot support allocations without 2008 // BOT updates. So we'll tag the dummy region as eden to avoid that. 2009 dummy_region->set_eden(); 2010 // Make sure it's full. 2011 dummy_region->set_top(dummy_region->end()); 2012 G1AllocRegion::setup(this, dummy_region); 2013 2014 _allocator->init_mutator_alloc_region(); 2015 2016 // Do create of the monitoring and management support so that 2017 // values in the heap have been properly initialized. 2018 _g1mm = new G1MonitoringSupport(this); 2019 2020 G1StringDedup::initialize(); 2021 2022 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC); 2023 for (uint i = 0; i < ParallelGCThreads; i++) { 2024 new (&_preserved_objs[i]) OopAndMarkOopStack(); 2025 } 2026 2027 return JNI_OK; 2028 } 2029 2030 void G1CollectedHeap::stop() { 2031 // Stop all concurrent threads. We do this to make sure these threads 2032 // do not continue to execute and access resources (e.g. logging) 2033 // that are destroyed during shutdown. 2034 _cg1r->stop(); 2035 _cmThread->stop(); 2036 if (G1StringDedup::is_enabled()) { 2037 G1StringDedup::stop(); 2038 } 2039 } 2040 2041 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2042 return HeapRegion::max_region_size(); 2043 } 2044 2045 void G1CollectedHeap::post_initialize() { 2046 CollectedHeap::post_initialize(); 2047 ref_processing_init(); 2048 } 2049 2050 void G1CollectedHeap::ref_processing_init() { 2051 // Reference processing in G1 currently works as follows: 2052 // 2053 // * There are two reference processor instances. One is 2054 // used to record and process discovered references 2055 // during concurrent marking; the other is used to 2056 // record and process references during STW pauses 2057 // (both full and incremental). 2058 // * Both ref processors need to 'span' the entire heap as 2059 // the regions in the collection set may be dotted around. 2060 // 2061 // * For the concurrent marking ref processor: 2062 // * Reference discovery is enabled at initial marking. 2063 // * Reference discovery is disabled and the discovered 2064 // references processed etc during remarking. 2065 // * Reference discovery is MT (see below). 2066 // * Reference discovery requires a barrier (see below). 2067 // * Reference processing may or may not be MT 2068 // (depending on the value of ParallelRefProcEnabled 2069 // and ParallelGCThreads). 2070 // * A full GC disables reference discovery by the CM 2071 // ref processor and abandons any entries on it's 2072 // discovered lists. 2073 // 2074 // * For the STW processor: 2075 // * Non MT discovery is enabled at the start of a full GC. 2076 // * Processing and enqueueing during a full GC is non-MT. 2077 // * During a full GC, references are processed after marking. 2078 // 2079 // * Discovery (may or may not be MT) is enabled at the start 2080 // of an incremental evacuation pause. 2081 // * References are processed near the end of a STW evacuation pause. 2082 // * For both types of GC: 2083 // * Discovery is atomic - i.e. not concurrent. 2084 // * Reference discovery will not need a barrier. 2085 2086 MemRegion mr = reserved_region(); 2087 2088 // Concurrent Mark ref processor 2089 _ref_processor_cm = 2090 new ReferenceProcessor(mr, // span 2091 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2092 // mt processing 2093 ParallelGCThreads, 2094 // degree of mt processing 2095 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2096 // mt discovery 2097 MAX2(ParallelGCThreads, ConcGCThreads), 2098 // degree of mt discovery 2099 false, 2100 // Reference discovery is not atomic 2101 &_is_alive_closure_cm); 2102 // is alive closure 2103 // (for efficiency/performance) 2104 2105 // STW ref processor 2106 _ref_processor_stw = 2107 new ReferenceProcessor(mr, // span 2108 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2109 // mt processing 2110 ParallelGCThreads, 2111 // degree of mt processing 2112 (ParallelGCThreads > 1), 2113 // mt discovery 2114 ParallelGCThreads, 2115 // degree of mt discovery 2116 true, 2117 // Reference discovery is atomic 2118 &_is_alive_closure_stw); 2119 // is alive closure 2120 // (for efficiency/performance) 2121 } 2122 2123 CollectorPolicy* G1CollectedHeap::collector_policy() const { 2124 return g1_policy(); 2125 } 2126 2127 size_t G1CollectedHeap::capacity() const { 2128 return _hrm.length() * HeapRegion::GrainBytes; 2129 } 2130 2131 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2132 hr->reset_gc_time_stamp(); 2133 } 2134 2135 #ifndef PRODUCT 2136 2137 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2138 private: 2139 unsigned _gc_time_stamp; 2140 bool _failures; 2141 2142 public: 2143 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2144 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2145 2146 virtual bool doHeapRegion(HeapRegion* hr) { 2147 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2148 if (_gc_time_stamp != region_gc_time_stamp) { 2149 log_info(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr), 2150 region_gc_time_stamp, _gc_time_stamp); 2151 _failures = true; 2152 } 2153 return false; 2154 } 2155 2156 bool failures() { return _failures; } 2157 }; 2158 2159 void G1CollectedHeap::check_gc_time_stamps() { 2160 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2161 heap_region_iterate(&cl); 2162 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2163 } 2164 #endif // PRODUCT 2165 2166 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) { 2167 _cg1r->hot_card_cache()->drain(cl, worker_i); 2168 } 2169 2170 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) { 2171 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2172 size_t n_completed_buffers = 0; 2173 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2174 n_completed_buffers++; 2175 } 2176 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 2177 dcqs.clear_n_completed_buffers(); 2178 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2179 } 2180 2181 // Computes the sum of the storage used by the various regions. 2182 size_t G1CollectedHeap::used() const { 2183 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 2184 if (_archive_allocator != NULL) { 2185 result += _archive_allocator->used(); 2186 } 2187 return result; 2188 } 2189 2190 size_t G1CollectedHeap::used_unlocked() const { 2191 return _summary_bytes_used; 2192 } 2193 2194 class SumUsedClosure: public HeapRegionClosure { 2195 size_t _used; 2196 public: 2197 SumUsedClosure() : _used(0) {} 2198 bool doHeapRegion(HeapRegion* r) { 2199 _used += r->used(); 2200 return false; 2201 } 2202 size_t result() { return _used; } 2203 }; 2204 2205 size_t G1CollectedHeap::recalculate_used() const { 2206 double recalculate_used_start = os::elapsedTime(); 2207 2208 SumUsedClosure blk; 2209 heap_region_iterate(&blk); 2210 2211 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2212 return blk.result(); 2213 } 2214 2215 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 2216 switch (cause) { 2217 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2218 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 2219 case GCCause::_update_allocation_context_stats_inc: return true; 2220 case GCCause::_wb_conc_mark: return true; 2221 default : return false; 2222 } 2223 } 2224 2225 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2226 switch (cause) { 2227 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2228 case GCCause::_g1_humongous_allocation: return true; 2229 default: return is_user_requested_concurrent_full_gc(cause); 2230 } 2231 } 2232 2233 #ifndef PRODUCT 2234 void G1CollectedHeap::allocate_dummy_regions() { 2235 // Let's fill up most of the region 2236 size_t word_size = HeapRegion::GrainWords - 1024; 2237 // And as a result the region we'll allocate will be humongous. 2238 guarantee(is_humongous(word_size), "sanity"); 2239 2240 // _filler_array_max_size is set to humongous object threshold 2241 // but temporarily change it to use CollectedHeap::fill_with_object(). 2242 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2243 2244 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2245 // Let's use the existing mechanism for the allocation 2246 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2247 AllocationContext::system()); 2248 if (dummy_obj != NULL) { 2249 MemRegion mr(dummy_obj, word_size); 2250 CollectedHeap::fill_with_object(mr); 2251 } else { 2252 // If we can't allocate once, we probably cannot allocate 2253 // again. Let's get out of the loop. 2254 break; 2255 } 2256 } 2257 } 2258 #endif // !PRODUCT 2259 2260 void G1CollectedHeap::increment_old_marking_cycles_started() { 2261 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2262 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2263 "Wrong marking cycle count (started: %d, completed: %d)", 2264 _old_marking_cycles_started, _old_marking_cycles_completed); 2265 2266 _old_marking_cycles_started++; 2267 } 2268 2269 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2270 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2271 2272 // We assume that if concurrent == true, then the caller is a 2273 // concurrent thread that was joined the Suspendible Thread 2274 // Set. If there's ever a cheap way to check this, we should add an 2275 // assert here. 2276 2277 // Given that this method is called at the end of a Full GC or of a 2278 // concurrent cycle, and those can be nested (i.e., a Full GC can 2279 // interrupt a concurrent cycle), the number of full collections 2280 // completed should be either one (in the case where there was no 2281 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2282 // behind the number of full collections started. 2283 2284 // This is the case for the inner caller, i.e. a Full GC. 2285 assert(concurrent || 2286 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2287 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2288 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2289 "is inconsistent with _old_marking_cycles_completed = %u", 2290 _old_marking_cycles_started, _old_marking_cycles_completed); 2291 2292 // This is the case for the outer caller, i.e. the concurrent cycle. 2293 assert(!concurrent || 2294 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2295 "for outer caller (concurrent cycle): " 2296 "_old_marking_cycles_started = %u " 2297 "is inconsistent with _old_marking_cycles_completed = %u", 2298 _old_marking_cycles_started, _old_marking_cycles_completed); 2299 2300 _old_marking_cycles_completed += 1; 2301 2302 // We need to clear the "in_progress" flag in the CM thread before 2303 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2304 // is set) so that if a waiter requests another System.gc() it doesn't 2305 // incorrectly see that a marking cycle is still in progress. 2306 if (concurrent) { 2307 _cmThread->set_idle(); 2308 } 2309 2310 // This notify_all() will ensure that a thread that called 2311 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2312 // and it's waiting for a full GC to finish will be woken up. It is 2313 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2314 FullGCCount_lock->notify_all(); 2315 } 2316 2317 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2318 GCIdMarkAndRestore conc_gc_id_mark; 2319 collector_state()->set_concurrent_cycle_started(true); 2320 _gc_timer_cm->register_gc_start(start_time); 2321 2322 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2323 trace_heap_before_gc(_gc_tracer_cm); 2324 _cmThread->set_gc_id(GCId::current()); 2325 } 2326 2327 void G1CollectedHeap::register_concurrent_cycle_end() { 2328 if (collector_state()->concurrent_cycle_started()) { 2329 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id()); 2330 if (_cm->has_aborted()) { 2331 _gc_tracer_cm->report_concurrent_mode_failure(); 2332 } 2333 2334 _gc_timer_cm->register_gc_end(); 2335 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2336 2337 // Clear state variables to prepare for the next concurrent cycle. 2338 collector_state()->set_concurrent_cycle_started(false); 2339 _heap_summary_sent = false; 2340 } 2341 } 2342 2343 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2344 if (collector_state()->concurrent_cycle_started()) { 2345 // This function can be called when: 2346 // the cleanup pause is run 2347 // the concurrent cycle is aborted before the cleanup pause. 2348 // the concurrent cycle is aborted after the cleanup pause, 2349 // but before the concurrent cycle end has been registered. 2350 // Make sure that we only send the heap information once. 2351 if (!_heap_summary_sent) { 2352 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id()); 2353 trace_heap_after_gc(_gc_tracer_cm); 2354 _heap_summary_sent = true; 2355 } 2356 } 2357 } 2358 2359 void G1CollectedHeap::collect(GCCause::Cause cause) { 2360 assert_heap_not_locked(); 2361 2362 uint gc_count_before; 2363 uint old_marking_count_before; 2364 uint full_gc_count_before; 2365 bool retry_gc; 2366 2367 do { 2368 retry_gc = false; 2369 2370 { 2371 MutexLocker ml(Heap_lock); 2372 2373 // Read the GC count while holding the Heap_lock 2374 gc_count_before = total_collections(); 2375 full_gc_count_before = total_full_collections(); 2376 old_marking_count_before = _old_marking_cycles_started; 2377 } 2378 2379 if (should_do_concurrent_full_gc(cause)) { 2380 // Schedule an initial-mark evacuation pause that will start a 2381 // concurrent cycle. We're setting word_size to 0 which means that 2382 // we are not requesting a post-GC allocation. 2383 VM_G1IncCollectionPause op(gc_count_before, 2384 0, /* word_size */ 2385 true, /* should_initiate_conc_mark */ 2386 g1_policy()->max_pause_time_ms(), 2387 cause); 2388 op.set_allocation_context(AllocationContext::current()); 2389 2390 VMThread::execute(&op); 2391 if (!op.pause_succeeded()) { 2392 if (old_marking_count_before == _old_marking_cycles_started) { 2393 retry_gc = op.should_retry_gc(); 2394 } else { 2395 // A Full GC happened while we were trying to schedule the 2396 // initial-mark GC. No point in starting a new cycle given 2397 // that the whole heap was collected anyway. 2398 } 2399 2400 if (retry_gc) { 2401 if (GCLocker::is_active_and_needs_gc()) { 2402 GCLocker::stall_until_clear(); 2403 } 2404 } 2405 } 2406 } else { 2407 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2408 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2409 2410 // Schedule a standard evacuation pause. We're setting word_size 2411 // to 0 which means that we are not requesting a post-GC allocation. 2412 VM_G1IncCollectionPause op(gc_count_before, 2413 0, /* word_size */ 2414 false, /* should_initiate_conc_mark */ 2415 g1_policy()->max_pause_time_ms(), 2416 cause); 2417 VMThread::execute(&op); 2418 } else { 2419 // Schedule a Full GC. 2420 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2421 VMThread::execute(&op); 2422 } 2423 } 2424 } while (retry_gc); 2425 } 2426 2427 bool G1CollectedHeap::is_in(const void* p) const { 2428 if (_hrm.reserved().contains(p)) { 2429 // Given that we know that p is in the reserved space, 2430 // heap_region_containing() should successfully 2431 // return the containing region. 2432 HeapRegion* hr = heap_region_containing(p); 2433 return hr->is_in(p); 2434 } else { 2435 return false; 2436 } 2437 } 2438 2439 #ifdef ASSERT 2440 bool G1CollectedHeap::is_in_exact(const void* p) const { 2441 bool contains = reserved_region().contains(p); 2442 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2443 if (contains && available) { 2444 return true; 2445 } else { 2446 return false; 2447 } 2448 } 2449 #endif 2450 2451 bool G1CollectedHeap::obj_in_cs(oop obj) { 2452 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj); 2453 return r != NULL && r->in_collection_set(); 2454 } 2455 2456 // Iteration functions. 2457 2458 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2459 2460 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2461 ExtendedOopClosure* _cl; 2462 public: 2463 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2464 bool doHeapRegion(HeapRegion* r) { 2465 if (!r->is_continues_humongous()) { 2466 r->oop_iterate(_cl); 2467 } 2468 return false; 2469 } 2470 }; 2471 2472 // Iterates an ObjectClosure over all objects within a HeapRegion. 2473 2474 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2475 ObjectClosure* _cl; 2476 public: 2477 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2478 bool doHeapRegion(HeapRegion* r) { 2479 if (!r->is_continues_humongous()) { 2480 r->object_iterate(_cl); 2481 } 2482 return false; 2483 } 2484 }; 2485 2486 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2487 IterateObjectClosureRegionClosure blk(cl); 2488 heap_region_iterate(&blk); 2489 } 2490 2491 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2492 _hrm.iterate(cl); 2493 } 2494 2495 void 2496 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, 2497 uint worker_id, 2498 HeapRegionClaimer *hrclaimer, 2499 bool concurrent) const { 2500 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); 2501 } 2502 2503 // Clear the cached CSet starting regions and (more importantly) 2504 // the time stamps. Called when we reset the GC time stamp. 2505 void G1CollectedHeap::clear_cset_start_regions() { 2506 assert(_worker_cset_start_region != NULL, "sanity"); 2507 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2508 2509 for (uint i = 0; i < ParallelGCThreads; i++) { 2510 _worker_cset_start_region[i] = NULL; 2511 _worker_cset_start_region_time_stamp[i] = 0; 2512 } 2513 } 2514 2515 // Given the id of a worker, obtain or calculate a suitable 2516 // starting region for iterating over the current collection set. 2517 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2518 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2519 2520 HeapRegion* result = NULL; 2521 unsigned gc_time_stamp = get_gc_time_stamp(); 2522 2523 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2524 // Cached starting region for current worker was set 2525 // during the current pause - so it's valid. 2526 // Note: the cached starting heap region may be NULL 2527 // (when the collection set is empty). 2528 result = _worker_cset_start_region[worker_i]; 2529 assert(result == NULL || result->in_collection_set(), "sanity"); 2530 return result; 2531 } 2532 2533 // The cached entry was not valid so let's calculate 2534 // a suitable starting heap region for this worker. 2535 2536 // We want the parallel threads to start their collection 2537 // set iteration at different collection set regions to 2538 // avoid contention. 2539 // If we have: 2540 // n collection set regions 2541 // p threads 2542 // Then thread t will start at region floor ((t * n) / p) 2543 2544 result = g1_policy()->collection_set(); 2545 uint cs_size = g1_policy()->cset_region_length(); 2546 uint active_workers = workers()->active_workers(); 2547 2548 uint end_ind = (cs_size * worker_i) / active_workers; 2549 uint start_ind = 0; 2550 2551 if (worker_i > 0 && 2552 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2553 // Previous workers starting region is valid 2554 // so let's iterate from there 2555 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2556 OrderAccess::loadload(); 2557 result = _worker_cset_start_region[worker_i - 1]; 2558 } 2559 2560 for (uint i = start_ind; i < end_ind; i++) { 2561 result = result->next_in_collection_set(); 2562 } 2563 2564 // Note: the calculated starting heap region may be NULL 2565 // (when the collection set is empty). 2566 assert(result == NULL || result->in_collection_set(), "sanity"); 2567 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2568 "should be updated only once per pause"); 2569 _worker_cset_start_region[worker_i] = result; 2570 OrderAccess::storestore(); 2571 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2572 return result; 2573 } 2574 2575 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2576 HeapRegion* r = g1_policy()->collection_set(); 2577 while (r != NULL) { 2578 HeapRegion* next = r->next_in_collection_set(); 2579 if (cl->doHeapRegion(r)) { 2580 cl->incomplete(); 2581 return; 2582 } 2583 r = next; 2584 } 2585 } 2586 2587 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2588 HeapRegionClosure *cl) { 2589 if (r == NULL) { 2590 // The CSet is empty so there's nothing to do. 2591 return; 2592 } 2593 2594 assert(r->in_collection_set(), 2595 "Start region must be a member of the collection set."); 2596 HeapRegion* cur = r; 2597 while (cur != NULL) { 2598 HeapRegion* next = cur->next_in_collection_set(); 2599 if (cl->doHeapRegion(cur) && false) { 2600 cl->incomplete(); 2601 return; 2602 } 2603 cur = next; 2604 } 2605 cur = g1_policy()->collection_set(); 2606 while (cur != r) { 2607 HeapRegion* next = cur->next_in_collection_set(); 2608 if (cl->doHeapRegion(cur) && false) { 2609 cl->incomplete(); 2610 return; 2611 } 2612 cur = next; 2613 } 2614 } 2615 2616 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2617 HeapRegion* result = _hrm.next_region_in_heap(from); 2618 while (result != NULL && result->is_pinned()) { 2619 result = _hrm.next_region_in_heap(result); 2620 } 2621 return result; 2622 } 2623 2624 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2625 HeapRegion* hr = heap_region_containing(addr); 2626 return hr->block_start(addr); 2627 } 2628 2629 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2630 HeapRegion* hr = heap_region_containing(addr); 2631 return hr->block_size(addr); 2632 } 2633 2634 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2635 HeapRegion* hr = heap_region_containing(addr); 2636 return hr->block_is_obj(addr); 2637 } 2638 2639 bool G1CollectedHeap::supports_tlab_allocation() const { 2640 return true; 2641 } 2642 2643 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2644 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2645 } 2646 2647 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2648 return young_list()->eden_used_bytes(); 2649 } 2650 2651 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2652 // must be equal to the humongous object limit. 2653 size_t G1CollectedHeap::max_tlab_size() const { 2654 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment); 2655 } 2656 2657 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2658 AllocationContext_t context = AllocationContext::current(); 2659 return _allocator->unsafe_max_tlab_alloc(context); 2660 } 2661 2662 size_t G1CollectedHeap::max_capacity() const { 2663 return _hrm.reserved().byte_size(); 2664 } 2665 2666 jlong G1CollectedHeap::millis_since_last_gc() { 2667 // assert(false, "NYI"); 2668 return 0; 2669 } 2670 2671 void G1CollectedHeap::prepare_for_verify() { 2672 _verifier->prepare_for_verify(); 2673 } 2674 2675 void G1CollectedHeap::verify(VerifyOption vo) { 2676 _verifier->verify(vo); 2677 } 2678 2679 class PrintRegionClosure: public HeapRegionClosure { 2680 outputStream* _st; 2681 public: 2682 PrintRegionClosure(outputStream* st) : _st(st) {} 2683 bool doHeapRegion(HeapRegion* r) { 2684 r->print_on(_st); 2685 return false; 2686 } 2687 }; 2688 2689 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2690 const HeapRegion* hr, 2691 const VerifyOption vo) const { 2692 switch (vo) { 2693 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2694 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2695 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive(); 2696 default: ShouldNotReachHere(); 2697 } 2698 return false; // keep some compilers happy 2699 } 2700 2701 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2702 const VerifyOption vo) const { 2703 switch (vo) { 2704 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2705 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2706 case VerifyOption_G1UseMarkWord: { 2707 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj); 2708 return !obj->is_gc_marked() && !hr->is_archive(); 2709 } 2710 default: ShouldNotReachHere(); 2711 } 2712 return false; // keep some compilers happy 2713 } 2714 2715 void G1CollectedHeap::print_on(outputStream* st) const { 2716 st->print(" %-20s", "garbage-first heap"); 2717 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2718 capacity()/K, used_unlocked()/K); 2719 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")", 2720 p2i(_hrm.reserved().start()), 2721 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords), 2722 p2i(_hrm.reserved().end())); 2723 st->cr(); 2724 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2725 uint young_regions = _young_list->length(); 2726 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2727 (size_t) young_regions * HeapRegion::GrainBytes / K); 2728 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 2729 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2730 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2731 st->cr(); 2732 MetaspaceAux::print_on(st); 2733 } 2734 2735 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2736 print_on(st); 2737 2738 // Print the per-region information. 2739 st->cr(); 2740 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2741 "HS=humongous(starts), HC=humongous(continues), " 2742 "CS=collection set, F=free, A=archive, TS=gc time stamp, " 2743 "AC=allocation context, " 2744 "TAMS=top-at-mark-start (previous, next)"); 2745 PrintRegionClosure blk(st); 2746 heap_region_iterate(&blk); 2747 } 2748 2749 void G1CollectedHeap::print_on_error(outputStream* st) const { 2750 this->CollectedHeap::print_on_error(st); 2751 2752 if (_cm != NULL) { 2753 st->cr(); 2754 _cm->print_on_error(st); 2755 } 2756 } 2757 2758 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2759 workers()->print_worker_threads_on(st); 2760 _cmThread->print_on(st); 2761 st->cr(); 2762 _cm->print_worker_threads_on(st); 2763 _cg1r->print_worker_threads_on(st); 2764 if (G1StringDedup::is_enabled()) { 2765 G1StringDedup::print_worker_threads_on(st); 2766 } 2767 } 2768 2769 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2770 workers()->threads_do(tc); 2771 tc->do_thread(_cmThread); 2772 _cg1r->threads_do(tc); 2773 if (G1StringDedup::is_enabled()) { 2774 G1StringDedup::threads_do(tc); 2775 } 2776 } 2777 2778 void G1CollectedHeap::print_tracing_info() const { 2779 // We'll overload this to mean "trace GC pause statistics." 2780 if (TraceYoungGenTime || TraceOldGenTime) { 2781 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 2782 // to that. 2783 g1_policy()->print_tracing_info(); 2784 } 2785 g1_rem_set()->print_summary_info(); 2786 concurrent_mark()->print_summary_info(); 2787 g1_policy()->print_yg_surv_rate_info(); 2788 } 2789 2790 #ifndef PRODUCT 2791 // Helpful for debugging RSet issues. 2792 2793 class PrintRSetsClosure : public HeapRegionClosure { 2794 private: 2795 const char* _msg; 2796 size_t _occupied_sum; 2797 2798 public: 2799 bool doHeapRegion(HeapRegion* r) { 2800 HeapRegionRemSet* hrrs = r->rem_set(); 2801 size_t occupied = hrrs->occupied(); 2802 _occupied_sum += occupied; 2803 2804 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2805 if (occupied == 0) { 2806 tty->print_cr(" RSet is empty"); 2807 } else { 2808 hrrs->print(); 2809 } 2810 tty->print_cr("----------"); 2811 return false; 2812 } 2813 2814 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2815 tty->cr(); 2816 tty->print_cr("========================================"); 2817 tty->print_cr("%s", msg); 2818 tty->cr(); 2819 } 2820 2821 ~PrintRSetsClosure() { 2822 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2823 tty->print_cr("========================================"); 2824 tty->cr(); 2825 } 2826 }; 2827 2828 void G1CollectedHeap::print_cset_rsets() { 2829 PrintRSetsClosure cl("Printing CSet RSets"); 2830 collection_set_iterate(&cl); 2831 } 2832 2833 void G1CollectedHeap::print_all_rsets() { 2834 PrintRSetsClosure cl("Printing All RSets");; 2835 heap_region_iterate(&cl); 2836 } 2837 #endif // PRODUCT 2838 2839 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2840 YoungList* young_list = heap()->young_list(); 2841 2842 size_t eden_used_bytes = young_list->eden_used_bytes(); 2843 size_t survivor_used_bytes = young_list->survivor_used_bytes(); 2844 2845 size_t eden_capacity_bytes = 2846 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2847 2848 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2849 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes); 2850 } 2851 2852 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2853 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2854 stats->unused(), stats->used(), stats->region_end_waste(), 2855 stats->regions_filled(), stats->direct_allocated(), 2856 stats->failure_used(), stats->failure_waste()); 2857 } 2858 2859 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2860 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2861 gc_tracer->report_gc_heap_summary(when, heap_summary); 2862 2863 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2864 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2865 } 2866 2867 2868 G1CollectedHeap* G1CollectedHeap::heap() { 2869 CollectedHeap* heap = Universe::heap(); 2870 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2871 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); 2872 return (G1CollectedHeap*)heap; 2873 } 2874 2875 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 2876 // always_do_update_barrier = false; 2877 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2878 // Fill TLAB's and such 2879 accumulate_statistics_all_tlabs(); 2880 ensure_parsability(true); 2881 2882 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2883 } 2884 2885 void G1CollectedHeap::gc_epilogue(bool full) { 2886 // we are at the end of the GC. Total collections has already been increased. 2887 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2888 2889 // FIXME: what is this about? 2890 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2891 // is set. 2892 #if defined(COMPILER2) || INCLUDE_JVMCI 2893 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2894 #endif 2895 // always_do_update_barrier = true; 2896 2897 resize_all_tlabs(); 2898 allocation_context_stats().update(full); 2899 2900 // We have just completed a GC. Update the soft reference 2901 // policy with the new heap occupancy 2902 Universe::update_heap_info_at_gc(); 2903 } 2904 2905 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2906 uint gc_count_before, 2907 bool* succeeded, 2908 GCCause::Cause gc_cause) { 2909 assert_heap_not_locked_and_not_at_safepoint(); 2910 g1_policy()->record_stop_world_start(); 2911 VM_G1IncCollectionPause op(gc_count_before, 2912 word_size, 2913 false, /* should_initiate_conc_mark */ 2914 g1_policy()->max_pause_time_ms(), 2915 gc_cause); 2916 2917 op.set_allocation_context(AllocationContext::current()); 2918 VMThread::execute(&op); 2919 2920 HeapWord* result = op.result(); 2921 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 2922 assert(result == NULL || ret_succeeded, 2923 "the result should be NULL if the VM did not succeed"); 2924 *succeeded = ret_succeeded; 2925 2926 assert_heap_not_locked(); 2927 return result; 2928 } 2929 2930 void 2931 G1CollectedHeap::doConcurrentMark() { 2932 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 2933 if (!_cmThread->in_progress()) { 2934 _cmThread->set_started(); 2935 CGC_lock->notify(); 2936 } 2937 } 2938 2939 size_t G1CollectedHeap::pending_card_num() { 2940 size_t extra_cards = 0; 2941 JavaThread *curr = Threads::first(); 2942 while (curr != NULL) { 2943 DirtyCardQueue& dcq = curr->dirty_card_queue(); 2944 extra_cards += dcq.size(); 2945 curr = curr->next(); 2946 } 2947 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2948 size_t buffer_size = dcqs.buffer_size(); 2949 size_t buffer_num = dcqs.completed_buffers_num(); 2950 2951 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 2952 // in bytes - not the number of 'entries'. We need to convert 2953 // into a number of cards. 2954 return (buffer_size * buffer_num + extra_cards) / oopSize; 2955 } 2956 2957 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 2958 private: 2959 size_t _total_humongous; 2960 size_t _candidate_humongous; 2961 2962 DirtyCardQueue _dcq; 2963 2964 // We don't nominate objects with many remembered set entries, on 2965 // the assumption that such objects are likely still live. 2966 bool is_remset_small(HeapRegion* region) const { 2967 HeapRegionRemSet* const rset = region->rem_set(); 2968 return G1EagerReclaimHumongousObjectsWithStaleRefs 2969 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) 2970 : rset->is_empty(); 2971 } 2972 2973 bool is_typeArray_region(HeapRegion* region) const { 2974 return oop(region->bottom())->is_typeArray(); 2975 } 2976 2977 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { 2978 assert(region->is_starts_humongous(), "Must start a humongous object"); 2979 2980 // Candidate selection must satisfy the following constraints 2981 // while concurrent marking is in progress: 2982 // 2983 // * In order to maintain SATB invariants, an object must not be 2984 // reclaimed if it was allocated before the start of marking and 2985 // has not had its references scanned. Such an object must have 2986 // its references (including type metadata) scanned to ensure no 2987 // live objects are missed by the marking process. Objects 2988 // allocated after the start of concurrent marking don't need to 2989 // be scanned. 2990 // 2991 // * An object must not be reclaimed if it is on the concurrent 2992 // mark stack. Objects allocated after the start of concurrent 2993 // marking are never pushed on the mark stack. 2994 // 2995 // Nominating only objects allocated after the start of concurrent 2996 // marking is sufficient to meet both constraints. This may miss 2997 // some objects that satisfy the constraints, but the marking data 2998 // structures don't support efficiently performing the needed 2999 // additional tests or scrubbing of the mark stack. 3000 // 3001 // However, we presently only nominate is_typeArray() objects. 3002 // A humongous object containing references induces remembered 3003 // set entries on other regions. In order to reclaim such an 3004 // object, those remembered sets would need to be cleaned up. 3005 // 3006 // We also treat is_typeArray() objects specially, allowing them 3007 // to be reclaimed even if allocated before the start of 3008 // concurrent mark. For this we rely on mark stack insertion to 3009 // exclude is_typeArray() objects, preventing reclaiming an object 3010 // that is in the mark stack. We also rely on the metadata for 3011 // such objects to be built-in and so ensured to be kept live. 3012 // Frequent allocation and drop of large binary blobs is an 3013 // important use case for eager reclaim, and this special handling 3014 // may reduce needed headroom. 3015 3016 return is_typeArray_region(region) && is_remset_small(region); 3017 } 3018 3019 public: 3020 RegisterHumongousWithInCSetFastTestClosure() 3021 : _total_humongous(0), 3022 _candidate_humongous(0), 3023 _dcq(&JavaThread::dirty_card_queue_set()) { 3024 } 3025 3026 virtual bool doHeapRegion(HeapRegion* r) { 3027 if (!r->is_starts_humongous()) { 3028 return false; 3029 } 3030 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3031 3032 bool is_candidate = humongous_region_is_candidate(g1h, r); 3033 uint rindex = r->hrm_index(); 3034 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 3035 if (is_candidate) { 3036 _candidate_humongous++; 3037 g1h->register_humongous_region_with_cset(rindex); 3038 // Is_candidate already filters out humongous object with large remembered sets. 3039 // If we have a humongous object with a few remembered sets, we simply flush these 3040 // remembered set entries into the DCQS. That will result in automatic 3041 // re-evaluation of their remembered set entries during the following evacuation 3042 // phase. 3043 if (!r->rem_set()->is_empty()) { 3044 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 3045 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 3046 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 3047 HeapRegionRemSetIterator hrrs(r->rem_set()); 3048 size_t card_index; 3049 while (hrrs.has_next(card_index)) { 3050 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 3051 // The remembered set might contain references to already freed 3052 // regions. Filter out such entries to avoid failing card table 3053 // verification. 3054 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) { 3055 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 3056 *card_ptr = CardTableModRefBS::dirty_card_val(); 3057 _dcq.enqueue(card_ptr); 3058 } 3059 } 3060 } 3061 assert(hrrs.n_yielded() == r->rem_set()->occupied(), 3062 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", 3063 hrrs.n_yielded(), r->rem_set()->occupied()); 3064 r->rem_set()->clear_locked(); 3065 } 3066 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 3067 } 3068 _total_humongous++; 3069 3070 return false; 3071 } 3072 3073 size_t total_humongous() const { return _total_humongous; } 3074 size_t candidate_humongous() const { return _candidate_humongous; } 3075 3076 void flush_rem_set_entries() { _dcq.flush(); } 3077 }; 3078 3079 void G1CollectedHeap::register_humongous_regions_with_cset() { 3080 if (!G1EagerReclaimHumongousObjects) { 3081 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 3082 return; 3083 } 3084 double time = os::elapsed_counter(); 3085 3086 // Collect reclaim candidate information and register candidates with cset. 3087 RegisterHumongousWithInCSetFastTestClosure cl; 3088 heap_region_iterate(&cl); 3089 3090 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 3091 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 3092 cl.total_humongous(), 3093 cl.candidate_humongous()); 3094 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3095 3096 // Finally flush all remembered set entries to re-check into the global DCQS. 3097 cl.flush_rem_set_entries(); 3098 } 3099 3100 class VerifyRegionRemSetClosure : public HeapRegionClosure { 3101 public: 3102 bool doHeapRegion(HeapRegion* hr) { 3103 if (!hr->is_archive() && !hr->is_continues_humongous()) { 3104 hr->verify_rem_set(); 3105 } 3106 return false; 3107 } 3108 }; 3109 3110 #ifdef ASSERT 3111 class VerifyCSetClosure: public HeapRegionClosure { 3112 public: 3113 bool doHeapRegion(HeapRegion* hr) { 3114 // Here we check that the CSet region's RSet is ready for parallel 3115 // iteration. The fields that we'll verify are only manipulated 3116 // when the region is part of a CSet and is collected. Afterwards, 3117 // we reset these fields when we clear the region's RSet (when the 3118 // region is freed) so they are ready when the region is 3119 // re-allocated. The only exception to this is if there's an 3120 // evacuation failure and instead of freeing the region we leave 3121 // it in the heap. In that case, we reset these fields during 3122 // evacuation failure handling. 3123 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3124 3125 // Here's a good place to add any other checks we'd like to 3126 // perform on CSet regions. 3127 return false; 3128 } 3129 }; 3130 #endif // ASSERT 3131 3132 uint G1CollectedHeap::num_task_queues() const { 3133 return _task_queues->size(); 3134 } 3135 3136 #if TASKQUEUE_STATS 3137 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3138 st->print_raw_cr("GC Task Stats"); 3139 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3140 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3141 } 3142 3143 void G1CollectedHeap::print_taskqueue_stats() const { 3144 if (!develop_log_is_enabled(Trace, gc, task, stats)) { 3145 return; 3146 } 3147 LogHandle(gc, task, stats) log; 3148 ResourceMark rm; 3149 outputStream* st = log.trace_stream(); 3150 3151 print_taskqueue_stats_hdr(st); 3152 3153 TaskQueueStats totals; 3154 const uint n = num_task_queues(); 3155 for (uint i = 0; i < n; ++i) { 3156 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 3157 totals += task_queue(i)->stats; 3158 } 3159 st->print_raw("tot "); totals.print(st); st->cr(); 3160 3161 DEBUG_ONLY(totals.verify()); 3162 } 3163 3164 void G1CollectedHeap::reset_taskqueue_stats() { 3165 const uint n = num_task_queues(); 3166 for (uint i = 0; i < n; ++i) { 3167 task_queue(i)->stats.reset(); 3168 } 3169 } 3170 #endif // TASKQUEUE_STATS 3171 3172 void G1CollectedHeap::log_gc_footer() { 3173 if (evacuation_failed()) { 3174 log_info(gc)("To-space exhausted"); 3175 } 3176 3177 g1_policy()->print_phases(); 3178 3179 g1_policy()->print_detailed_heap_transition(); 3180 } 3181 3182 3183 void G1CollectedHeap::wait_for_root_region_scanning() { 3184 double scan_wait_start = os::elapsedTime(); 3185 // We have to wait until the CM threads finish scanning the 3186 // root regions as it's the only way to ensure that all the 3187 // objects on them have been correctly scanned before we start 3188 // moving them during the GC. 3189 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3190 double wait_time_ms = 0.0; 3191 if (waited) { 3192 double scan_wait_end = os::elapsedTime(); 3193 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3194 } 3195 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3196 } 3197 3198 bool 3199 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3200 assert_at_safepoint(true /* should_be_vm_thread */); 3201 guarantee(!is_gc_active(), "collection is not reentrant"); 3202 3203 if (GCLocker::check_active_before_gc()) { 3204 return false; 3205 } 3206 3207 _gc_timer_stw->register_gc_start(); 3208 3209 GCIdMark gc_id_mark; 3210 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3211 3212 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3213 ResourceMark rm; 3214 3215 wait_for_root_region_scanning(); 3216 3217 print_heap_before_gc(); 3218 trace_heap_before_gc(_gc_tracer_stw); 3219 3220 _verifier->verify_region_sets_optional(); 3221 _verifier->verify_dirty_young_regions(); 3222 3223 // This call will decide whether this pause is an initial-mark 3224 // pause. If it is, during_initial_mark_pause() will return true 3225 // for the duration of this pause. 3226 g1_policy()->decide_on_conc_mark_initiation(); 3227 3228 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3229 assert(!collector_state()->during_initial_mark_pause() || 3230 collector_state()->gcs_are_young(), "sanity"); 3231 3232 // We also do not allow mixed GCs during marking. 3233 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity"); 3234 3235 // Record whether this pause is an initial mark. When the current 3236 // thread has completed its logging output and it's safe to signal 3237 // the CM thread, the flag's value in the policy has been reset. 3238 bool should_start_conc_mark = collector_state()->during_initial_mark_pause(); 3239 3240 // Inner scope for scope based logging, timers, and stats collection 3241 { 3242 EvacuationInfo evacuation_info; 3243 3244 if (collector_state()->during_initial_mark_pause()) { 3245 // We are about to start a marking cycle, so we increment the 3246 // full collection counter. 3247 increment_old_marking_cycles_started(); 3248 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3249 } 3250 3251 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 3252 3253 GCTraceCPUTime tcpu; 3254 3255 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 3256 workers()->active_workers(), 3257 Threads::number_of_non_daemon_threads()); 3258 workers()->set_active_workers(active_workers); 3259 FormatBuffer<> gc_string("Pause "); 3260 if (collector_state()->during_initial_mark_pause()) { 3261 gc_string.append("Initial Mark"); 3262 } else if (collector_state()->gcs_are_young()) { 3263 gc_string.append("Young"); 3264 } else { 3265 gc_string.append("Mixed"); 3266 } 3267 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true); 3268 3269 g1_policy()->note_gc_start(active_workers); 3270 3271 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3272 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3273 3274 // If the secondary_free_list is not empty, append it to the 3275 // free_list. No need to wait for the cleanup operation to finish; 3276 // the region allocation code will check the secondary_free_list 3277 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3278 // set, skip this step so that the region allocation code has to 3279 // get entries from the secondary_free_list. 3280 if (!G1StressConcRegionFreeing) { 3281 append_secondary_free_list_if_not_empty_with_lock(); 3282 } 3283 3284 assert(check_young_list_well_formed(), "young list should be well formed"); 3285 3286 // Don't dynamically change the number of GC threads this early. A value of 3287 // 0 is used to indicate serial work. When parallel work is done, 3288 // it will be set. 3289 3290 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3291 IsGCActiveMark x; 3292 3293 gc_prologue(false); 3294 increment_total_collections(false /* full gc */); 3295 increment_gc_time_stamp(); 3296 3297 if (VerifyRememberedSets) { 3298 log_info(gc, verify)("[Verifying RemSets before GC]"); 3299 VerifyRegionRemSetClosure v_cl; 3300 heap_region_iterate(&v_cl); 3301 } 3302 3303 _verifier->verify_before_gc(); 3304 3305 _verifier->check_bitmaps("GC Start"); 3306 3307 #if defined(COMPILER2) || INCLUDE_JVMCI 3308 DerivedPointerTable::clear(); 3309 #endif 3310 3311 // Please see comment in g1CollectedHeap.hpp and 3312 // G1CollectedHeap::ref_processing_init() to see how 3313 // reference processing currently works in G1. 3314 3315 // Enable discovery in the STW reference processor 3316 if (g1_policy()->should_process_references()) { 3317 ref_processor_stw()->enable_discovery(); 3318 } else { 3319 ref_processor_stw()->disable_discovery(); 3320 } 3321 3322 { 3323 // We want to temporarily turn off discovery by the 3324 // CM ref processor, if necessary, and turn it back on 3325 // on again later if we do. Using a scoped 3326 // NoRefDiscovery object will do this. 3327 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3328 3329 // Forget the current alloc region (we might even choose it to be part 3330 // of the collection set!). 3331 _allocator->release_mutator_alloc_region(); 3332 3333 // This timing is only used by the ergonomics to handle our pause target. 3334 // It is unclear why this should not include the full pause. We will 3335 // investigate this in CR 7178365. 3336 // 3337 // Preserving the old comment here if that helps the investigation: 3338 // 3339 // The elapsed time induced by the start time below deliberately elides 3340 // the possible verification above. 3341 double sample_start_time_sec = os::elapsedTime(); 3342 3343 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3344 3345 if (collector_state()->during_initial_mark_pause()) { 3346 concurrent_mark()->checkpointRootsInitialPre(); 3347 } 3348 3349 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms); 3350 g1_policy()->finalize_old_cset_part(time_remaining_ms); 3351 3352 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length()); 3353 3354 // Make sure the remembered sets are up to date. This needs to be 3355 // done before register_humongous_regions_with_cset(), because the 3356 // remembered sets are used there to choose eager reclaim candidates. 3357 // If the remembered sets are not up to date we might miss some 3358 // entries that need to be handled. 3359 g1_rem_set()->cleanupHRRS(); 3360 3361 register_humongous_regions_with_cset(); 3362 3363 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3364 3365 _cm->note_start_of_gc(); 3366 // We call this after finalize_cset() to 3367 // ensure that the CSet has been finalized. 3368 _cm->verify_no_cset_oops(); 3369 3370 if (_hr_printer.is_active()) { 3371 HeapRegion* hr = g1_policy()->collection_set(); 3372 while (hr != NULL) { 3373 _hr_printer.cset(hr); 3374 hr = hr->next_in_collection_set(); 3375 } 3376 } 3377 3378 #ifdef ASSERT 3379 VerifyCSetClosure cl; 3380 collection_set_iterate(&cl); 3381 #endif // ASSERT 3382 3383 // Initialize the GC alloc regions. 3384 _allocator->init_gc_alloc_regions(evacuation_info); 3385 3386 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length()); 3387 pre_evacuate_collection_set(); 3388 3389 // Actually do the work... 3390 evacuate_collection_set(evacuation_info, &per_thread_states); 3391 3392 post_evacuate_collection_set(evacuation_info, &per_thread_states); 3393 3394 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 3395 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words); 3396 3397 eagerly_reclaim_humongous_regions(); 3398 3399 g1_policy()->clear_collection_set(); 3400 3401 // Start a new incremental collection set for the next pause. 3402 g1_policy()->start_incremental_cset_building(); 3403 3404 clear_cset_fast_test(); 3405 3406 _young_list->reset_sampled_info(); 3407 3408 // Don't check the whole heap at this point as the 3409 // GC alloc regions from this pause have been tagged 3410 // as survivors and moved on to the survivor list. 3411 // Survivor regions will fail the !is_young() check. 3412 assert(check_young_list_empty(false /* check_heap */), 3413 "young list should be empty"); 3414 3415 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 3416 _young_list->first_survivor_region(), 3417 _young_list->last_survivor_region()); 3418 3419 _young_list->reset_auxilary_lists(); 3420 3421 if (evacuation_failed()) { 3422 set_used(recalculate_used()); 3423 if (_archive_allocator != NULL) { 3424 _archive_allocator->clear_used(); 3425 } 3426 for (uint i = 0; i < ParallelGCThreads; i++) { 3427 if (_evacuation_failed_info_array[i].has_failed()) { 3428 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3429 } 3430 } 3431 } else { 3432 // The "used" of the the collection set have already been subtracted 3433 // when they were freed. Add in the bytes evacuated. 3434 increase_used(g1_policy()->bytes_copied_during_gc()); 3435 } 3436 3437 if (collector_state()->during_initial_mark_pause()) { 3438 // We have to do this before we notify the CM threads that 3439 // they can start working to make sure that all the 3440 // appropriate initialization is done on the CM object. 3441 concurrent_mark()->checkpointRootsInitialPost(); 3442 collector_state()->set_mark_in_progress(true); 3443 // Note that we don't actually trigger the CM thread at 3444 // this point. We do that later when we're sure that 3445 // the current thread has completed its logging output. 3446 } 3447 3448 allocate_dummy_regions(); 3449 3450 _allocator->init_mutator_alloc_region(); 3451 3452 { 3453 size_t expand_bytes = g1_policy()->expansion_amount(); 3454 if (expand_bytes > 0) { 3455 size_t bytes_before = capacity(); 3456 // No need for an ergo logging here, 3457 // expansion_amount() does this when it returns a value > 0. 3458 double expand_ms; 3459 if (!expand(expand_bytes, &expand_ms)) { 3460 // We failed to expand the heap. Cannot do anything about it. 3461 } 3462 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 3463 } 3464 } 3465 3466 // We redo the verification but now wrt to the new CSet which 3467 // has just got initialized after the previous CSet was freed. 3468 _cm->verify_no_cset_oops(); 3469 _cm->note_end_of_gc(); 3470 3471 // This timing is only used by the ergonomics to handle our pause target. 3472 // It is unclear why this should not include the full pause. We will 3473 // investigate this in CR 7178365. 3474 double sample_end_time_sec = os::elapsedTime(); 3475 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3476 size_t total_cards_scanned = per_thread_states.total_cards_scanned(); 3477 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned); 3478 3479 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before()); 3480 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 3481 3482 MemoryService::track_memory_usage(); 3483 3484 // In prepare_for_verify() below we'll need to scan the deferred 3485 // update buffers to bring the RSets up-to-date if 3486 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 3487 // the update buffers we'll probably need to scan cards on the 3488 // regions we just allocated to (i.e., the GC alloc 3489 // regions). However, during the last GC we called 3490 // set_saved_mark() on all the GC alloc regions, so card 3491 // scanning might skip the [saved_mark_word()...top()] area of 3492 // those regions (i.e., the area we allocated objects into 3493 // during the last GC). But it shouldn't. Given that 3494 // saved_mark_word() is conditional on whether the GC time stamp 3495 // on the region is current or not, by incrementing the GC time 3496 // stamp here we invalidate all the GC time stamps on all the 3497 // regions and saved_mark_word() will simply return top() for 3498 // all the regions. This is a nicer way of ensuring this rather 3499 // than iterating over the regions and fixing them. In fact, the 3500 // GC time stamp increment here also ensures that 3501 // saved_mark_word() will return top() between pauses, i.e., 3502 // during concurrent refinement. So we don't need the 3503 // is_gc_active() check to decided which top to use when 3504 // scanning cards (see CR 7039627). 3505 increment_gc_time_stamp(); 3506 3507 if (VerifyRememberedSets) { 3508 log_info(gc, verify)("[Verifying RemSets after GC]"); 3509 VerifyRegionRemSetClosure v_cl; 3510 heap_region_iterate(&v_cl); 3511 } 3512 3513 _verifier->verify_after_gc(); 3514 _verifier->check_bitmaps("GC End"); 3515 3516 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 3517 ref_processor_stw()->verify_no_references_recorded(); 3518 3519 // CM reference discovery will be re-enabled if necessary. 3520 } 3521 3522 #ifdef TRACESPINNING 3523 ParallelTaskTerminator::print_termination_counts(); 3524 #endif 3525 3526 gc_epilogue(false); 3527 } 3528 3529 // Print the remainder of the GC log output. 3530 log_gc_footer(); 3531 3532 // It is not yet to safe to tell the concurrent mark to 3533 // start as we have some optional output below. We don't want the 3534 // output from the concurrent mark thread interfering with this 3535 // logging output either. 3536 3537 _hrm.verify_optional(); 3538 _verifier->verify_region_sets_optional(); 3539 3540 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3541 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3542 3543 print_heap_after_gc(); 3544 trace_heap_after_gc(_gc_tracer_stw); 3545 3546 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3547 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3548 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3549 // before any GC notifications are raised. 3550 g1mm()->update_sizes(); 3551 3552 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3553 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 3554 _gc_timer_stw->register_gc_end(); 3555 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3556 } 3557 // It should now be safe to tell the concurrent mark thread to start 3558 // without its logging output interfering with the logging output 3559 // that came from the pause. 3560 3561 if (should_start_conc_mark) { 3562 // CAUTION: after the doConcurrentMark() call below, 3563 // the concurrent marking thread(s) could be running 3564 // concurrently with us. Make sure that anything after 3565 // this point does not assume that we are the only GC thread 3566 // running. Note: of course, the actual marking work will 3567 // not start until the safepoint itself is released in 3568 // SuspendibleThreadSet::desynchronize(). 3569 doConcurrentMark(); 3570 } 3571 3572 return true; 3573 } 3574 3575 void G1CollectedHeap::restore_preserved_marks() { 3576 G1RestorePreservedMarksTask rpm_task(_preserved_objs); 3577 workers()->run_task(&rpm_task); 3578 } 3579 3580 void G1CollectedHeap::remove_self_forwarding_pointers() { 3581 G1ParRemoveSelfForwardPtrsTask rsfp_task; 3582 workers()->run_task(&rsfp_task); 3583 } 3584 3585 void G1CollectedHeap::restore_after_evac_failure() { 3586 double remove_self_forwards_start = os::elapsedTime(); 3587 3588 remove_self_forwarding_pointers(); 3589 restore_preserved_marks(); 3590 3591 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3592 } 3593 3594 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 3595 if (!_evacuation_failed) { 3596 _evacuation_failed = true; 3597 } 3598 3599 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3600 3601 // We want to call the "for_promotion_failure" version only in the 3602 // case of a promotion failure. 3603 if (m->must_be_preserved_for_promotion_failure(obj)) { 3604 OopAndMarkOop elem(obj, m); 3605 _preserved_objs[worker_id].push(elem); 3606 } 3607 } 3608 3609 bool G1ParEvacuateFollowersClosure::offer_termination() { 3610 G1ParScanThreadState* const pss = par_scan_state(); 3611 start_term_time(); 3612 const bool res = terminator()->offer_termination(); 3613 end_term_time(); 3614 return res; 3615 } 3616 3617 void G1ParEvacuateFollowersClosure::do_void() { 3618 G1ParScanThreadState* const pss = par_scan_state(); 3619 pss->trim_queue(); 3620 do { 3621 pss->steal_and_trim_queue(queues()); 3622 } while (!offer_termination()); 3623 } 3624 3625 class G1ParTask : public AbstractGangTask { 3626 protected: 3627 G1CollectedHeap* _g1h; 3628 G1ParScanThreadStateSet* _pss; 3629 RefToScanQueueSet* _queues; 3630 G1RootProcessor* _root_processor; 3631 ParallelTaskTerminator _terminator; 3632 uint _n_workers; 3633 3634 public: 3635 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 3636 : AbstractGangTask("G1 collection"), 3637 _g1h(g1h), 3638 _pss(per_thread_states), 3639 _queues(task_queues), 3640 _root_processor(root_processor), 3641 _terminator(n_workers, _queues), 3642 _n_workers(n_workers) 3643 {} 3644 3645 void work(uint worker_id) { 3646 if (worker_id >= _n_workers) return; // no work needed this round 3647 3648 double start_sec = os::elapsedTime(); 3649 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 3650 3651 { 3652 ResourceMark rm; 3653 HandleMark hm; 3654 3655 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 3656 3657 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3658 pss->set_ref_processor(rp); 3659 3660 double start_strong_roots_sec = os::elapsedTime(); 3661 3662 _root_processor->evacuate_roots(pss->closures(), worker_id); 3663 3664 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss); 3665 3666 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid 3667 // treating the nmethods visited to act as roots for concurrent marking. 3668 // We only want to make sure that the oops in the nmethods are adjusted with regard to the 3669 // objects copied by the current evacuation. 3670 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl, 3671 pss->closures()->weak_codeblobs(), 3672 worker_id); 3673 3674 _pss->add_cards_scanned(worker_id, cards_scanned); 3675 3676 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 3677 3678 double term_sec = 0.0; 3679 size_t evac_term_attempts = 0; 3680 { 3681 double start = os::elapsedTime(); 3682 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator); 3683 evac.do_void(); 3684 3685 evac_term_attempts = evac.term_attempts(); 3686 term_sec = evac.term_time(); 3687 double elapsed_sec = os::elapsedTime() - start; 3688 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 3689 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 3690 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 3691 } 3692 3693 assert(pss->queue_is_empty(), "should be empty"); 3694 3695 if (log_is_enabled(Debug, gc, task, stats)) { 3696 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3697 size_t lab_waste; 3698 size_t lab_undo_waste; 3699 pss->waste(lab_waste, lab_undo_waste); 3700 _g1h->print_termination_stats(worker_id, 3701 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 3702 strong_roots_sec * 1000.0, /* strong roots time */ 3703 term_sec * 1000.0, /* evac term time */ 3704 evac_term_attempts, /* evac term attempts */ 3705 lab_waste, /* alloc buffer waste */ 3706 lab_undo_waste /* undo waste */ 3707 ); 3708 } 3709 3710 // Close the inner scope so that the ResourceMark and HandleMark 3711 // destructors are executed here and are included as part of the 3712 // "GC Worker Time". 3713 } 3714 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 3715 } 3716 }; 3717 3718 void G1CollectedHeap::print_termination_stats_hdr() { 3719 log_debug(gc, task, stats)("GC Termination Stats"); 3720 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 3721 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo"); 3722 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 3723 } 3724 3725 void G1CollectedHeap::print_termination_stats(uint worker_id, 3726 double elapsed_ms, 3727 double strong_roots_ms, 3728 double term_ms, 3729 size_t term_attempts, 3730 size_t alloc_buffer_waste, 3731 size_t undo_waste) const { 3732 log_debug(gc, task, stats) 3733 ("%3d %9.2f %9.2f %6.2f " 3734 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 3735 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 3736 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 3737 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 3738 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 3739 alloc_buffer_waste * HeapWordSize / K, 3740 undo_waste * HeapWordSize / K); 3741 } 3742 3743 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 3744 private: 3745 BoolObjectClosure* _is_alive; 3746 int _initial_string_table_size; 3747 int _initial_symbol_table_size; 3748 3749 bool _process_strings; 3750 int _strings_processed; 3751 int _strings_removed; 3752 3753 bool _process_symbols; 3754 int _symbols_processed; 3755 int _symbols_removed; 3756 3757 public: 3758 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 3759 AbstractGangTask("String/Symbol Unlinking"), 3760 _is_alive(is_alive), 3761 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 3762 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 3763 3764 _initial_string_table_size = StringTable::the_table()->table_size(); 3765 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 3766 if (process_strings) { 3767 StringTable::clear_parallel_claimed_index(); 3768 } 3769 if (process_symbols) { 3770 SymbolTable::clear_parallel_claimed_index(); 3771 } 3772 } 3773 3774 ~G1StringSymbolTableUnlinkTask() { 3775 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 3776 "claim value %d after unlink less than initial string table size %d", 3777 StringTable::parallel_claimed_index(), _initial_string_table_size); 3778 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 3779 "claim value %d after unlink less than initial symbol table size %d", 3780 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size); 3781 3782 log_debug(gc, stringdedup)("Cleaned string and symbol table, " 3783 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, " 3784 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed", 3785 strings_processed(), strings_removed(), 3786 symbols_processed(), symbols_removed()); 3787 } 3788 3789 void work(uint worker_id) { 3790 int strings_processed = 0; 3791 int strings_removed = 0; 3792 int symbols_processed = 0; 3793 int symbols_removed = 0; 3794 if (_process_strings) { 3795 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 3796 Atomic::add(strings_processed, &_strings_processed); 3797 Atomic::add(strings_removed, &_strings_removed); 3798 } 3799 if (_process_symbols) { 3800 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 3801 Atomic::add(symbols_processed, &_symbols_processed); 3802 Atomic::add(symbols_removed, &_symbols_removed); 3803 } 3804 } 3805 3806 size_t strings_processed() const { return (size_t)_strings_processed; } 3807 size_t strings_removed() const { return (size_t)_strings_removed; } 3808 3809 size_t symbols_processed() const { return (size_t)_symbols_processed; } 3810 size_t symbols_removed() const { return (size_t)_symbols_removed; } 3811 }; 3812 3813 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 3814 private: 3815 static Monitor* _lock; 3816 3817 BoolObjectClosure* const _is_alive; 3818 const bool _unloading_occurred; 3819 const uint _num_workers; 3820 3821 // Variables used to claim nmethods. 3822 nmethod* _first_nmethod; 3823 volatile nmethod* _claimed_nmethod; 3824 3825 // The list of nmethods that need to be processed by the second pass. 3826 volatile nmethod* _postponed_list; 3827 volatile uint _num_entered_barrier; 3828 3829 public: 3830 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 3831 _is_alive(is_alive), 3832 _unloading_occurred(unloading_occurred), 3833 _num_workers(num_workers), 3834 _first_nmethod(NULL), 3835 _claimed_nmethod(NULL), 3836 _postponed_list(NULL), 3837 _num_entered_barrier(0) 3838 { 3839 nmethod::increase_unloading_clock(); 3840 // Get first alive nmethod 3841 NMethodIterator iter = NMethodIterator(); 3842 if(iter.next_alive()) { 3843 _first_nmethod = iter.method(); 3844 } 3845 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 3846 } 3847 3848 ~G1CodeCacheUnloadingTask() { 3849 CodeCache::verify_clean_inline_caches(); 3850 3851 CodeCache::set_needs_cache_clean(false); 3852 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 3853 3854 CodeCache::verify_icholder_relocations(); 3855 } 3856 3857 private: 3858 void add_to_postponed_list(nmethod* nm) { 3859 nmethod* old; 3860 do { 3861 old = (nmethod*)_postponed_list; 3862 nm->set_unloading_next(old); 3863 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 3864 } 3865 3866 void clean_nmethod(nmethod* nm) { 3867 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 3868 3869 if (postponed) { 3870 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 3871 add_to_postponed_list(nm); 3872 } 3873 3874 // Mark that this thread has been cleaned/unloaded. 3875 // After this call, it will be safe to ask if this nmethod was unloaded or not. 3876 nm->set_unloading_clock(nmethod::global_unloading_clock()); 3877 } 3878 3879 void clean_nmethod_postponed(nmethod* nm) { 3880 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 3881 } 3882 3883 static const int MaxClaimNmethods = 16; 3884 3885 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 3886 nmethod* first; 3887 NMethodIterator last; 3888 3889 do { 3890 *num_claimed_nmethods = 0; 3891 3892 first = (nmethod*)_claimed_nmethod; 3893 last = NMethodIterator(first); 3894 3895 if (first != NULL) { 3896 3897 for (int i = 0; i < MaxClaimNmethods; i++) { 3898 if (!last.next_alive()) { 3899 break; 3900 } 3901 claimed_nmethods[i] = last.method(); 3902 (*num_claimed_nmethods)++; 3903 } 3904 } 3905 3906 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 3907 } 3908 3909 nmethod* claim_postponed_nmethod() { 3910 nmethod* claim; 3911 nmethod* next; 3912 3913 do { 3914 claim = (nmethod*)_postponed_list; 3915 if (claim == NULL) { 3916 return NULL; 3917 } 3918 3919 next = claim->unloading_next(); 3920 3921 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 3922 3923 return claim; 3924 } 3925 3926 public: 3927 // Mark that we're done with the first pass of nmethod cleaning. 3928 void barrier_mark(uint worker_id) { 3929 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3930 _num_entered_barrier++; 3931 if (_num_entered_barrier == _num_workers) { 3932 ml.notify_all(); 3933 } 3934 } 3935 3936 // See if we have to wait for the other workers to 3937 // finish their first-pass nmethod cleaning work. 3938 void barrier_wait(uint worker_id) { 3939 if (_num_entered_barrier < _num_workers) { 3940 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3941 while (_num_entered_barrier < _num_workers) { 3942 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 3943 } 3944 } 3945 } 3946 3947 // Cleaning and unloading of nmethods. Some work has to be postponed 3948 // to the second pass, when we know which nmethods survive. 3949 void work_first_pass(uint worker_id) { 3950 // The first nmethods is claimed by the first worker. 3951 if (worker_id == 0 && _first_nmethod != NULL) { 3952 clean_nmethod(_first_nmethod); 3953 _first_nmethod = NULL; 3954 } 3955 3956 int num_claimed_nmethods; 3957 nmethod* claimed_nmethods[MaxClaimNmethods]; 3958 3959 while (true) { 3960 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 3961 3962 if (num_claimed_nmethods == 0) { 3963 break; 3964 } 3965 3966 for (int i = 0; i < num_claimed_nmethods; i++) { 3967 clean_nmethod(claimed_nmethods[i]); 3968 } 3969 } 3970 } 3971 3972 void work_second_pass(uint worker_id) { 3973 nmethod* nm; 3974 // Take care of postponed nmethods. 3975 while ((nm = claim_postponed_nmethod()) != NULL) { 3976 clean_nmethod_postponed(nm); 3977 } 3978 } 3979 }; 3980 3981 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 3982 3983 class G1KlassCleaningTask : public StackObj { 3984 BoolObjectClosure* _is_alive; 3985 volatile jint _clean_klass_tree_claimed; 3986 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 3987 3988 public: 3989 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 3990 _is_alive(is_alive), 3991 _clean_klass_tree_claimed(0), 3992 _klass_iterator() { 3993 } 3994 3995 private: 3996 bool claim_clean_klass_tree_task() { 3997 if (_clean_klass_tree_claimed) { 3998 return false; 3999 } 4000 4001 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 4002 } 4003 4004 InstanceKlass* claim_next_klass() { 4005 Klass* klass; 4006 do { 4007 klass =_klass_iterator.next_klass(); 4008 } while (klass != NULL && !klass->is_instance_klass()); 4009 4010 // this can be null so don't call InstanceKlass::cast 4011 return static_cast<InstanceKlass*>(klass); 4012 } 4013 4014 public: 4015 4016 void clean_klass(InstanceKlass* ik) { 4017 ik->clean_weak_instanceklass_links(_is_alive); 4018 } 4019 4020 void work() { 4021 ResourceMark rm; 4022 4023 // One worker will clean the subklass/sibling klass tree. 4024 if (claim_clean_klass_tree_task()) { 4025 Klass::clean_subklass_tree(_is_alive); 4026 } 4027 4028 // All workers will help cleaning the classes, 4029 InstanceKlass* klass; 4030 while ((klass = claim_next_klass()) != NULL) { 4031 clean_klass(klass); 4032 } 4033 } 4034 }; 4035 4036 // To minimize the remark pause times, the tasks below are done in parallel. 4037 class G1ParallelCleaningTask : public AbstractGangTask { 4038 private: 4039 G1StringSymbolTableUnlinkTask _string_symbol_task; 4040 G1CodeCacheUnloadingTask _code_cache_task; 4041 G1KlassCleaningTask _klass_cleaning_task; 4042 4043 public: 4044 // The constructor is run in the VMThread. 4045 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 4046 AbstractGangTask("Parallel Cleaning"), 4047 _string_symbol_task(is_alive, process_strings, process_symbols), 4048 _code_cache_task(num_workers, is_alive, unloading_occurred), 4049 _klass_cleaning_task(is_alive) { 4050 } 4051 4052 // The parallel work done by all worker threads. 4053 void work(uint worker_id) { 4054 // Do first pass of code cache cleaning. 4055 _code_cache_task.work_first_pass(worker_id); 4056 4057 // Let the threads mark that the first pass is done. 4058 _code_cache_task.barrier_mark(worker_id); 4059 4060 // Clean the Strings and Symbols. 4061 _string_symbol_task.work(worker_id); 4062 4063 // Wait for all workers to finish the first code cache cleaning pass. 4064 _code_cache_task.barrier_wait(worker_id); 4065 4066 // Do the second code cache cleaning work, which realize on 4067 // the liveness information gathered during the first pass. 4068 _code_cache_task.work_second_pass(worker_id); 4069 4070 // Clean all klasses that were not unloaded. 4071 _klass_cleaning_task.work(); 4072 } 4073 }; 4074 4075 4076 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 4077 bool process_strings, 4078 bool process_symbols, 4079 bool class_unloading_occurred) { 4080 uint n_workers = workers()->active_workers(); 4081 4082 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 4083 n_workers, class_unloading_occurred); 4084 workers()->run_task(&g1_unlink_task); 4085 } 4086 4087 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 4088 bool process_strings, bool process_symbols) { 4089 { 4090 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 4091 workers()->run_task(&g1_unlink_task); 4092 } 4093 4094 if (G1StringDedup::is_enabled()) { 4095 G1StringDedup::unlink(is_alive); 4096 } 4097 } 4098 4099 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 4100 private: 4101 DirtyCardQueueSet* _queue; 4102 G1CollectedHeap* _g1h; 4103 public: 4104 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 4105 _queue(queue), _g1h(g1h) { } 4106 4107 virtual void work(uint worker_id) { 4108 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 4109 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 4110 4111 RedirtyLoggedCardTableEntryClosure cl(_g1h); 4112 _queue->par_apply_closure_to_all_completed_buffers(&cl); 4113 4114 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 4115 } 4116 }; 4117 4118 void G1CollectedHeap::redirty_logged_cards() { 4119 double redirty_logged_cards_start = os::elapsedTime(); 4120 4121 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 4122 dirty_card_queue_set().reset_for_par_iteration(); 4123 workers()->run_task(&redirty_task); 4124 4125 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 4126 dcq.merge_bufferlists(&dirty_card_queue_set()); 4127 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 4128 4129 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 4130 } 4131 4132 // Weak Reference Processing support 4133 4134 // An always "is_alive" closure that is used to preserve referents. 4135 // If the object is non-null then it's alive. Used in the preservation 4136 // of referent objects that are pointed to by reference objects 4137 // discovered by the CM ref processor. 4138 class G1AlwaysAliveClosure: public BoolObjectClosure { 4139 G1CollectedHeap* _g1; 4140 public: 4141 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4142 bool do_object_b(oop p) { 4143 if (p != NULL) { 4144 return true; 4145 } 4146 return false; 4147 } 4148 }; 4149 4150 bool G1STWIsAliveClosure::do_object_b(oop p) { 4151 // An object is reachable if it is outside the collection set, 4152 // or is inside and copied. 4153 return !_g1->is_in_cset(p) || p->is_forwarded(); 4154 } 4155 4156 // Non Copying Keep Alive closure 4157 class G1KeepAliveClosure: public OopClosure { 4158 G1CollectedHeap* _g1; 4159 public: 4160 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4161 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 4162 void do_oop(oop* p) { 4163 oop obj = *p; 4164 assert(obj != NULL, "the caller should have filtered out NULL values"); 4165 4166 const InCSetState cset_state = _g1->in_cset_state(obj); 4167 if (!cset_state.is_in_cset_or_humongous()) { 4168 return; 4169 } 4170 if (cset_state.is_in_cset()) { 4171 assert( obj->is_forwarded(), "invariant" ); 4172 *p = obj->forwardee(); 4173 } else { 4174 assert(!obj->is_forwarded(), "invariant" ); 4175 assert(cset_state.is_humongous(), 4176 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 4177 _g1->set_humongous_is_live(obj); 4178 } 4179 } 4180 }; 4181 4182 // Copying Keep Alive closure - can be called from both 4183 // serial and parallel code as long as different worker 4184 // threads utilize different G1ParScanThreadState instances 4185 // and different queues. 4186 4187 class G1CopyingKeepAliveClosure: public OopClosure { 4188 G1CollectedHeap* _g1h; 4189 OopClosure* _copy_non_heap_obj_cl; 4190 G1ParScanThreadState* _par_scan_state; 4191 4192 public: 4193 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 4194 OopClosure* non_heap_obj_cl, 4195 G1ParScanThreadState* pss): 4196 _g1h(g1h), 4197 _copy_non_heap_obj_cl(non_heap_obj_cl), 4198 _par_scan_state(pss) 4199 {} 4200 4201 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 4202 virtual void do_oop( oop* p) { do_oop_work(p); } 4203 4204 template <class T> void do_oop_work(T* p) { 4205 oop obj = oopDesc::load_decode_heap_oop(p); 4206 4207 if (_g1h->is_in_cset_or_humongous(obj)) { 4208 // If the referent object has been forwarded (either copied 4209 // to a new location or to itself in the event of an 4210 // evacuation failure) then we need to update the reference 4211 // field and, if both reference and referent are in the G1 4212 // heap, update the RSet for the referent. 4213 // 4214 // If the referent has not been forwarded then we have to keep 4215 // it alive by policy. Therefore we have copy the referent. 4216 // 4217 // If the reference field is in the G1 heap then we can push 4218 // on the PSS queue. When the queue is drained (after each 4219 // phase of reference processing) the object and it's followers 4220 // will be copied, the reference field set to point to the 4221 // new location, and the RSet updated. Otherwise we need to 4222 // use the the non-heap or metadata closures directly to copy 4223 // the referent object and update the pointer, while avoiding 4224 // updating the RSet. 4225 4226 if (_g1h->is_in_g1_reserved(p)) { 4227 _par_scan_state->push_on_queue(p); 4228 } else { 4229 assert(!Metaspace::contains((const void*)p), 4230 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)); 4231 _copy_non_heap_obj_cl->do_oop(p); 4232 } 4233 } 4234 } 4235 }; 4236 4237 // Serial drain queue closure. Called as the 'complete_gc' 4238 // closure for each discovered list in some of the 4239 // reference processing phases. 4240 4241 class G1STWDrainQueueClosure: public VoidClosure { 4242 protected: 4243 G1CollectedHeap* _g1h; 4244 G1ParScanThreadState* _par_scan_state; 4245 4246 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4247 4248 public: 4249 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 4250 _g1h(g1h), 4251 _par_scan_state(pss) 4252 { } 4253 4254 void do_void() { 4255 G1ParScanThreadState* const pss = par_scan_state(); 4256 pss->trim_queue(); 4257 } 4258 }; 4259 4260 // Parallel Reference Processing closures 4261 4262 // Implementation of AbstractRefProcTaskExecutor for parallel reference 4263 // processing during G1 evacuation pauses. 4264 4265 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 4266 private: 4267 G1CollectedHeap* _g1h; 4268 G1ParScanThreadStateSet* _pss; 4269 RefToScanQueueSet* _queues; 4270 WorkGang* _workers; 4271 uint _active_workers; 4272 4273 public: 4274 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 4275 G1ParScanThreadStateSet* per_thread_states, 4276 WorkGang* workers, 4277 RefToScanQueueSet *task_queues, 4278 uint n_workers) : 4279 _g1h(g1h), 4280 _pss(per_thread_states), 4281 _queues(task_queues), 4282 _workers(workers), 4283 _active_workers(n_workers) 4284 { 4285 assert(n_workers > 0, "shouldn't call this otherwise"); 4286 } 4287 4288 // Executes the given task using concurrent marking worker threads. 4289 virtual void execute(ProcessTask& task); 4290 virtual void execute(EnqueueTask& task); 4291 }; 4292 4293 // Gang task for possibly parallel reference processing 4294 4295 class G1STWRefProcTaskProxy: public AbstractGangTask { 4296 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 4297 ProcessTask& _proc_task; 4298 G1CollectedHeap* _g1h; 4299 G1ParScanThreadStateSet* _pss; 4300 RefToScanQueueSet* _task_queues; 4301 ParallelTaskTerminator* _terminator; 4302 4303 public: 4304 G1STWRefProcTaskProxy(ProcessTask& proc_task, 4305 G1CollectedHeap* g1h, 4306 G1ParScanThreadStateSet* per_thread_states, 4307 RefToScanQueueSet *task_queues, 4308 ParallelTaskTerminator* terminator) : 4309 AbstractGangTask("Process reference objects in parallel"), 4310 _proc_task(proc_task), 4311 _g1h(g1h), 4312 _pss(per_thread_states), 4313 _task_queues(task_queues), 4314 _terminator(terminator) 4315 {} 4316 4317 virtual void work(uint worker_id) { 4318 // The reference processing task executed by a single worker. 4319 ResourceMark rm; 4320 HandleMark hm; 4321 4322 G1STWIsAliveClosure is_alive(_g1h); 4323 4324 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4325 pss->set_ref_processor(NULL); 4326 4327 // Keep alive closure. 4328 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 4329 4330 // Complete GC closure 4331 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator); 4332 4333 // Call the reference processing task's work routine. 4334 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 4335 4336 // Note we cannot assert that the refs array is empty here as not all 4337 // of the processing tasks (specifically phase2 - pp2_work) execute 4338 // the complete_gc closure (which ordinarily would drain the queue) so 4339 // the queue may not be empty. 4340 } 4341 }; 4342 4343 // Driver routine for parallel reference processing. 4344 // Creates an instance of the ref processing gang 4345 // task and has the worker threads execute it. 4346 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 4347 assert(_workers != NULL, "Need parallel worker threads."); 4348 4349 ParallelTaskTerminator terminator(_active_workers, _queues); 4350 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 4351 4352 _workers->run_task(&proc_task_proxy); 4353 } 4354 4355 // Gang task for parallel reference enqueueing. 4356 4357 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 4358 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 4359 EnqueueTask& _enq_task; 4360 4361 public: 4362 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 4363 AbstractGangTask("Enqueue reference objects in parallel"), 4364 _enq_task(enq_task) 4365 { } 4366 4367 virtual void work(uint worker_id) { 4368 _enq_task.work(worker_id); 4369 } 4370 }; 4371 4372 // Driver routine for parallel reference enqueueing. 4373 // Creates an instance of the ref enqueueing gang 4374 // task and has the worker threads execute it. 4375 4376 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 4377 assert(_workers != NULL, "Need parallel worker threads."); 4378 4379 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 4380 4381 _workers->run_task(&enq_task_proxy); 4382 } 4383 4384 // End of weak reference support closures 4385 4386 // Abstract task used to preserve (i.e. copy) any referent objects 4387 // that are in the collection set and are pointed to by reference 4388 // objects discovered by the CM ref processor. 4389 4390 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 4391 protected: 4392 G1CollectedHeap* _g1h; 4393 G1ParScanThreadStateSet* _pss; 4394 RefToScanQueueSet* _queues; 4395 ParallelTaskTerminator _terminator; 4396 uint _n_workers; 4397 4398 public: 4399 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) : 4400 AbstractGangTask("ParPreserveCMReferents"), 4401 _g1h(g1h), 4402 _pss(per_thread_states), 4403 _queues(task_queues), 4404 _terminator(workers, _queues), 4405 _n_workers(workers) 4406 { } 4407 4408 void work(uint worker_id) { 4409 ResourceMark rm; 4410 HandleMark hm; 4411 4412 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4413 pss->set_ref_processor(NULL); 4414 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 4415 4416 // Is alive closure 4417 G1AlwaysAliveClosure always_alive(_g1h); 4418 4419 // Copying keep alive closure. Applied to referent objects that need 4420 // to be copied. 4421 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 4422 4423 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 4424 4425 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 4426 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 4427 4428 // limit is set using max_num_q() - which was set using ParallelGCThreads. 4429 // So this must be true - but assert just in case someone decides to 4430 // change the worker ids. 4431 assert(worker_id < limit, "sanity"); 4432 assert(!rp->discovery_is_atomic(), "check this code"); 4433 4434 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 4435 for (uint idx = worker_id; idx < limit; idx += stride) { 4436 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 4437 4438 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 4439 while (iter.has_next()) { 4440 // Since discovery is not atomic for the CM ref processor, we 4441 // can see some null referent objects. 4442 iter.load_ptrs(DEBUG_ONLY(true)); 4443 oop ref = iter.obj(); 4444 4445 // This will filter nulls. 4446 if (iter.is_referent_alive()) { 4447 iter.make_referent_alive(); 4448 } 4449 iter.move_to_next(); 4450 } 4451 } 4452 4453 // Drain the queue - which may cause stealing 4454 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator); 4455 drain_queue.do_void(); 4456 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 4457 assert(pss->queue_is_empty(), "should be"); 4458 } 4459 }; 4460 4461 void G1CollectedHeap::process_weak_jni_handles() { 4462 double ref_proc_start = os::elapsedTime(); 4463 4464 G1STWIsAliveClosure is_alive(this); 4465 G1KeepAliveClosure keep_alive(this); 4466 JNIHandles::weak_oops_do(&is_alive, &keep_alive); 4467 4468 double ref_proc_time = os::elapsedTime() - ref_proc_start; 4469 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 4470 } 4471 4472 // Weak Reference processing during an evacuation pause (part 1). 4473 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 4474 double ref_proc_start = os::elapsedTime(); 4475 4476 ReferenceProcessor* rp = _ref_processor_stw; 4477 assert(rp->discovery_enabled(), "should have been enabled"); 4478 4479 // Any reference objects, in the collection set, that were 'discovered' 4480 // by the CM ref processor should have already been copied (either by 4481 // applying the external root copy closure to the discovered lists, or 4482 // by following an RSet entry). 4483 // 4484 // But some of the referents, that are in the collection set, that these 4485 // reference objects point to may not have been copied: the STW ref 4486 // processor would have seen that the reference object had already 4487 // been 'discovered' and would have skipped discovering the reference, 4488 // but would not have treated the reference object as a regular oop. 4489 // As a result the copy closure would not have been applied to the 4490 // referent object. 4491 // 4492 // We need to explicitly copy these referent objects - the references 4493 // will be processed at the end of remarking. 4494 // 4495 // We also need to do this copying before we process the reference 4496 // objects discovered by the STW ref processor in case one of these 4497 // referents points to another object which is also referenced by an 4498 // object discovered by the STW ref processor. 4499 4500 uint no_of_gc_workers = workers()->active_workers(); 4501 4502 G1ParPreserveCMReferentsTask keep_cm_referents(this, 4503 per_thread_states, 4504 no_of_gc_workers, 4505 _task_queues); 4506 4507 workers()->run_task(&keep_cm_referents); 4508 4509 // Closure to test whether a referent is alive. 4510 G1STWIsAliveClosure is_alive(this); 4511 4512 // Even when parallel reference processing is enabled, the processing 4513 // of JNI refs is serial and performed serially by the current thread 4514 // rather than by a worker. The following PSS will be used for processing 4515 // JNI refs. 4516 4517 // Use only a single queue for this PSS. 4518 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 4519 pss->set_ref_processor(NULL); 4520 assert(pss->queue_is_empty(), "pre-condition"); 4521 4522 // Keep alive closure. 4523 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss); 4524 4525 // Serial Complete GC closure 4526 G1STWDrainQueueClosure drain_queue(this, pss); 4527 4528 // Setup the soft refs policy... 4529 rp->setup_policy(false); 4530 4531 ReferenceProcessorStats stats; 4532 if (!rp->processing_is_mt()) { 4533 // Serial reference processing... 4534 stats = rp->process_discovered_references(&is_alive, 4535 &keep_alive, 4536 &drain_queue, 4537 NULL, 4538 _gc_timer_stw); 4539 } else { 4540 // Parallel reference processing 4541 assert(rp->num_q() == no_of_gc_workers, "sanity"); 4542 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 4543 4544 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers); 4545 stats = rp->process_discovered_references(&is_alive, 4546 &keep_alive, 4547 &drain_queue, 4548 &par_task_executor, 4549 _gc_timer_stw); 4550 } 4551 4552 _gc_tracer_stw->report_gc_reference_stats(stats); 4553 4554 // We have completed copying any necessary live referent objects. 4555 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 4556 4557 double ref_proc_time = os::elapsedTime() - ref_proc_start; 4558 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 4559 } 4560 4561 // Weak Reference processing during an evacuation pause (part 2). 4562 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 4563 double ref_enq_start = os::elapsedTime(); 4564 4565 ReferenceProcessor* rp = _ref_processor_stw; 4566 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 4567 4568 // Now enqueue any remaining on the discovered lists on to 4569 // the pending list. 4570 if (!rp->processing_is_mt()) { 4571 // Serial reference processing... 4572 rp->enqueue_discovered_references(); 4573 } else { 4574 // Parallel reference enqueueing 4575 4576 uint n_workers = workers()->active_workers(); 4577 4578 assert(rp->num_q() == n_workers, "sanity"); 4579 assert(n_workers <= rp->max_num_q(), "sanity"); 4580 4581 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers); 4582 rp->enqueue_discovered_references(&par_task_executor); 4583 } 4584 4585 rp->verify_no_references_recorded(); 4586 assert(!rp->discovery_enabled(), "should have been disabled"); 4587 4588 // FIXME 4589 // CM's reference processing also cleans up the string and symbol tables. 4590 // Should we do that here also? We could, but it is a serial operation 4591 // and could significantly increase the pause time. 4592 4593 double ref_enq_time = os::elapsedTime() - ref_enq_start; 4594 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 4595 } 4596 4597 void G1CollectedHeap::pre_evacuate_collection_set() { 4598 _expand_heap_after_alloc_failure = true; 4599 _evacuation_failed = false; 4600 4601 // Disable the hot card cache. 4602 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 4603 hot_card_cache->reset_hot_cache_claimed_index(); 4604 hot_card_cache->set_use_cache(false); 4605 4606 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 4607 } 4608 4609 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 4610 // Should G1EvacuationFailureALot be in effect for this GC? 4611 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 4612 4613 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 4614 double start_par_time_sec = os::elapsedTime(); 4615 double end_par_time_sec; 4616 4617 { 4618 const uint n_workers = workers()->active_workers(); 4619 G1RootProcessor root_processor(this, n_workers); 4620 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 4621 // InitialMark needs claim bits to keep track of the marked-through CLDs. 4622 if (collector_state()->during_initial_mark_pause()) { 4623 ClassLoaderDataGraph::clear_claimed_marks(); 4624 } 4625 4626 print_termination_stats_hdr(); 4627 4628 workers()->run_task(&g1_par_task); 4629 end_par_time_sec = os::elapsedTime(); 4630 4631 // Closing the inner scope will execute the destructor 4632 // for the G1RootProcessor object. We record the current 4633 // elapsed time before closing the scope so that time 4634 // taken for the destructor is NOT included in the 4635 // reported parallel time. 4636 } 4637 4638 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 4639 4640 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 4641 phase_times->record_par_time(par_time_ms); 4642 4643 double code_root_fixup_time_ms = 4644 (os::elapsedTime() - end_par_time_sec) * 1000.0; 4645 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 4646 } 4647 4648 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 4649 // Process any discovered reference objects - we have 4650 // to do this _before_ we retire the GC alloc regions 4651 // as we may have to copy some 'reachable' referent 4652 // objects (and their reachable sub-graphs) that were 4653 // not copied during the pause. 4654 if (g1_policy()->should_process_references()) { 4655 process_discovered_references(per_thread_states); 4656 } else { 4657 ref_processor_stw()->verify_no_references_recorded(); 4658 process_weak_jni_handles(); 4659 } 4660 4661 if (G1StringDedup::is_enabled()) { 4662 double fixup_start = os::elapsedTime(); 4663 4664 G1STWIsAliveClosure is_alive(this); 4665 G1KeepAliveClosure keep_alive(this); 4666 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times()); 4667 4668 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 4669 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms); 4670 } 4671 4672 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 4673 4674 if (evacuation_failed()) { 4675 restore_after_evac_failure(); 4676 4677 // Reset the G1EvacuationFailureALot counters and flags 4678 // Note: the values are reset only when an actual 4679 // evacuation failure occurs. 4680 NOT_PRODUCT(reset_evacuation_should_fail();) 4681 } 4682 4683 // Enqueue any remaining references remaining on the STW 4684 // reference processor's discovered lists. We need to do 4685 // this after the card table is cleaned (and verified) as 4686 // the act of enqueueing entries on to the pending list 4687 // will log these updates (and dirty their associated 4688 // cards). We need these updates logged to update any 4689 // RSets. 4690 if (g1_policy()->should_process_references()) { 4691 enqueue_discovered_references(per_thread_states); 4692 } else { 4693 g1_policy()->phase_times()->record_ref_enq_time(0); 4694 } 4695 4696 _allocator->release_gc_alloc_regions(evacuation_info); 4697 4698 per_thread_states->flush(); 4699 4700 record_obj_copy_mem_stats(); 4701 4702 _survivor_evac_stats.adjust_desired_plab_sz(); 4703 _old_evac_stats.adjust_desired_plab_sz(); 4704 4705 // Reset and re-enable the hot card cache. 4706 // Note the counts for the cards in the regions in the 4707 // collection set are reset when the collection set is freed. 4708 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 4709 hot_card_cache->reset_hot_cache(); 4710 hot_card_cache->set_use_cache(true); 4711 4712 purge_code_root_memory(); 4713 4714 redirty_logged_cards(); 4715 #if defined(COMPILER2) || INCLUDE_JVMCI 4716 DerivedPointerTable::update_pointers(); 4717 #endif 4718 } 4719 4720 void G1CollectedHeap::record_obj_copy_mem_stats() { 4721 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 4722 4723 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 4724 create_g1_evac_summary(&_old_evac_stats)); 4725 } 4726 4727 void G1CollectedHeap::free_region(HeapRegion* hr, 4728 FreeRegionList* free_list, 4729 bool par, 4730 bool locked) { 4731 assert(!hr->is_free(), "the region should not be free"); 4732 assert(!hr->is_empty(), "the region should not be empty"); 4733 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 4734 assert(free_list != NULL, "pre-condition"); 4735 4736 if (G1VerifyBitmaps) { 4737 MemRegion mr(hr->bottom(), hr->end()); 4738 concurrent_mark()->clearRangePrevBitmap(mr); 4739 } 4740 4741 // Clear the card counts for this region. 4742 // Note: we only need to do this if the region is not young 4743 // (since we don't refine cards in young regions). 4744 if (!hr->is_young()) { 4745 _cg1r->hot_card_cache()->reset_card_counts(hr); 4746 } 4747 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 4748 free_list->add_ordered(hr); 4749 } 4750 4751 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4752 FreeRegionList* free_list, 4753 bool par) { 4754 assert(hr->is_humongous(), "this is only for humongous regions"); 4755 assert(free_list != NULL, "pre-condition"); 4756 hr->clear_humongous(); 4757 free_region(hr, free_list, par); 4758 } 4759 4760 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 4761 const uint humongous_regions_removed) { 4762 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 4763 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4764 _old_set.bulk_remove(old_regions_removed); 4765 _humongous_set.bulk_remove(humongous_regions_removed); 4766 } 4767 4768 } 4769 4770 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4771 assert(list != NULL, "list can't be null"); 4772 if (!list->is_empty()) { 4773 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4774 _hrm.insert_list_into_free_list(list); 4775 } 4776 } 4777 4778 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4779 decrease_used(bytes); 4780 } 4781 4782 class G1ParCleanupCTTask : public AbstractGangTask { 4783 G1SATBCardTableModRefBS* _ct_bs; 4784 G1CollectedHeap* _g1h; 4785 HeapRegion* volatile _su_head; 4786 public: 4787 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 4788 G1CollectedHeap* g1h) : 4789 AbstractGangTask("G1 Par Cleanup CT Task"), 4790 _ct_bs(ct_bs), _g1h(g1h) { } 4791 4792 void work(uint worker_id) { 4793 HeapRegion* r; 4794 while (r = _g1h->pop_dirty_cards_region()) { 4795 clear_cards(r); 4796 } 4797 } 4798 4799 void clear_cards(HeapRegion* r) { 4800 // Cards of the survivors should have already been dirtied. 4801 if (!r->is_survivor()) { 4802 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 4803 } 4804 } 4805 }; 4806 4807 class G1ParScrubRemSetTask: public AbstractGangTask { 4808 protected: 4809 G1RemSet* _g1rs; 4810 BitMap* _region_bm; 4811 BitMap* _card_bm; 4812 HeapRegionClaimer _hrclaimer; 4813 4814 public: 4815 G1ParScrubRemSetTask(G1RemSet* g1_rs, BitMap* region_bm, BitMap* card_bm, uint num_workers) : 4816 AbstractGangTask("G1 ScrubRS"), 4817 _g1rs(g1_rs), 4818 _region_bm(region_bm), 4819 _card_bm(card_bm), 4820 _hrclaimer(num_workers) { 4821 } 4822 4823 void work(uint worker_id) { 4824 _g1rs->scrub(_region_bm, _card_bm, worker_id, &_hrclaimer); 4825 } 4826 }; 4827 4828 void G1CollectedHeap::scrub_rem_set(BitMap* region_bm, BitMap* card_bm) { 4829 uint num_workers = workers()->active_workers(); 4830 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), region_bm, card_bm, num_workers); 4831 workers()->run_task(&g1_par_scrub_rs_task); 4832 } 4833 4834 void G1CollectedHeap::cleanUpCardTable() { 4835 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 4836 double start = os::elapsedTime(); 4837 4838 { 4839 // Iterate over the dirty cards region list. 4840 G1ParCleanupCTTask cleanup_task(ct_bs, this); 4841 4842 workers()->run_task(&cleanup_task); 4843 #ifndef PRODUCT 4844 _verifier->verify_card_table_cleanup(); 4845 #endif 4846 } 4847 4848 double elapsed = os::elapsedTime() - start; 4849 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 4850 } 4851 4852 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4853 size_t pre_used = 0; 4854 FreeRegionList local_free_list("Local List for CSet Freeing"); 4855 4856 double young_time_ms = 0.0; 4857 double non_young_time_ms = 0.0; 4858 4859 // Since the collection set is a superset of the the young list, 4860 // all we need to do to clear the young list is clear its 4861 // head and length, and unlink any young regions in the code below 4862 _young_list->clear(); 4863 4864 G1CollectorPolicy* policy = g1_policy(); 4865 4866 double start_sec = os::elapsedTime(); 4867 bool non_young = true; 4868 4869 HeapRegion* cur = cs_head; 4870 int age_bound = -1; 4871 size_t rs_lengths = 0; 4872 4873 while (cur != NULL) { 4874 assert(!is_on_master_free_list(cur), "sanity"); 4875 if (non_young) { 4876 if (cur->is_young()) { 4877 double end_sec = os::elapsedTime(); 4878 double elapsed_ms = (end_sec - start_sec) * 1000.0; 4879 non_young_time_ms += elapsed_ms; 4880 4881 start_sec = os::elapsedTime(); 4882 non_young = false; 4883 } 4884 } else { 4885 if (!cur->is_young()) { 4886 double end_sec = os::elapsedTime(); 4887 double elapsed_ms = (end_sec - start_sec) * 1000.0; 4888 young_time_ms += elapsed_ms; 4889 4890 start_sec = os::elapsedTime(); 4891 non_young = true; 4892 } 4893 } 4894 4895 rs_lengths += cur->rem_set()->occupied_locked(); 4896 4897 HeapRegion* next = cur->next_in_collection_set(); 4898 assert(cur->in_collection_set(), "bad CS"); 4899 cur->set_next_in_collection_set(NULL); 4900 clear_in_cset(cur); 4901 4902 if (cur->is_young()) { 4903 int index = cur->young_index_in_cset(); 4904 assert(index != -1, "invariant"); 4905 assert((uint) index < policy->young_cset_region_length(), "invariant"); 4906 size_t words_survived = surviving_young_words[index]; 4907 cur->record_surv_words_in_group(words_survived); 4908 4909 // At this point the we have 'popped' cur from the collection set 4910 // (linked via next_in_collection_set()) but it is still in the 4911 // young list (linked via next_young_region()). Clear the 4912 // _next_young_region field. 4913 cur->set_next_young_region(NULL); 4914 } else { 4915 int index = cur->young_index_in_cset(); 4916 assert(index == -1, "invariant"); 4917 } 4918 4919 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 4920 (!cur->is_young() && cur->young_index_in_cset() == -1), 4921 "invariant" ); 4922 4923 if (!cur->evacuation_failed()) { 4924 MemRegion used_mr = cur->used_region(); 4925 4926 // And the region is empty. 4927 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 4928 pre_used += cur->used(); 4929 free_region(cur, &local_free_list, false /* par */, true /* locked */); 4930 } else { 4931 cur->uninstall_surv_rate_group(); 4932 if (cur->is_young()) { 4933 cur->set_young_index_in_cset(-1); 4934 } 4935 cur->set_evacuation_failed(false); 4936 // When moving a young gen region to old gen, we "allocate" that whole region 4937 // there. This is in addition to any already evacuated objects. Notify the 4938 // policy about that. 4939 // Old gen regions do not cause an additional allocation: both the objects 4940 // still in the region and the ones already moved are accounted for elsewhere. 4941 if (cur->is_young()) { 4942 policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes); 4943 } 4944 // The region is now considered to be old. 4945 cur->set_old(); 4946 // Do some allocation statistics accounting. Regions that failed evacuation 4947 // are always made old, so there is no need to update anything in the young 4948 // gen statistics, but we need to update old gen statistics. 4949 size_t used_words = cur->marked_bytes() / HeapWordSize; 4950 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words); 4951 _old_set.add(cur); 4952 evacuation_info.increment_collectionset_used_after(cur->used()); 4953 } 4954 cur = next; 4955 } 4956 4957 evacuation_info.set_regions_freed(local_free_list.length()); 4958 policy->record_max_rs_lengths(rs_lengths); 4959 policy->cset_regions_freed(); 4960 4961 double end_sec = os::elapsedTime(); 4962 double elapsed_ms = (end_sec - start_sec) * 1000.0; 4963 4964 if (non_young) { 4965 non_young_time_ms += elapsed_ms; 4966 } else { 4967 young_time_ms += elapsed_ms; 4968 } 4969 4970 prepend_to_freelist(&local_free_list); 4971 decrement_summary_bytes(pre_used); 4972 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 4973 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 4974 } 4975 4976 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4977 private: 4978 FreeRegionList* _free_region_list; 4979 HeapRegionSet* _proxy_set; 4980 uint _humongous_regions_removed; 4981 size_t _freed_bytes; 4982 public: 4983 4984 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4985 _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) { 4986 } 4987 4988 virtual bool doHeapRegion(HeapRegion* r) { 4989 if (!r->is_starts_humongous()) { 4990 return false; 4991 } 4992 4993 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4994 4995 oop obj = (oop)r->bottom(); 4996 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 4997 4998 // The following checks whether the humongous object is live are sufficient. 4999 // The main additional check (in addition to having a reference from the roots 5000 // or the young gen) is whether the humongous object has a remembered set entry. 5001 // 5002 // A humongous object cannot be live if there is no remembered set for it 5003 // because: 5004 // - there can be no references from within humongous starts regions referencing 5005 // the object because we never allocate other objects into them. 5006 // (I.e. there are no intra-region references that may be missed by the 5007 // remembered set) 5008 // - as soon there is a remembered set entry to the humongous starts region 5009 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 5010 // until the end of a concurrent mark. 5011 // 5012 // It is not required to check whether the object has been found dead by marking 5013 // or not, in fact it would prevent reclamation within a concurrent cycle, as 5014 // all objects allocated during that time are considered live. 5015 // SATB marking is even more conservative than the remembered set. 5016 // So if at this point in the collection there is no remembered set entry, 5017 // nobody has a reference to it. 5018 // At the start of collection we flush all refinement logs, and remembered sets 5019 // are completely up-to-date wrt to references to the humongous object. 5020 // 5021 // Other implementation considerations: 5022 // - never consider object arrays at this time because they would pose 5023 // considerable effort for cleaning up the the remembered sets. This is 5024 // required because stale remembered sets might reference locations that 5025 // are currently allocated into. 5026 uint region_idx = r->hrm_index(); 5027 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 5028 !r->rem_set()->is_empty()) { 5029 log_debug(gc, humongous)("Live humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d", 5030 region_idx, 5031 (size_t)obj->size() * HeapWordSize, 5032 p2i(r->bottom()), 5033 r->rem_set()->occupied(), 5034 r->rem_set()->strong_code_roots_list_length(), 5035 next_bitmap->isMarked(r->bottom()), 5036 g1h->is_humongous_reclaim_candidate(region_idx), 5037 obj->is_typeArray() 5038 ); 5039 return false; 5040 } 5041 5042 guarantee(obj->is_typeArray(), 5043 "Only eagerly reclaiming type arrays is supported, but the object " 5044 PTR_FORMAT " is not.", p2i(r->bottom())); 5045 5046 log_debug(gc, humongous)("Dead humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d", 5047 region_idx, 5048 (size_t)obj->size() * HeapWordSize, 5049 p2i(r->bottom()), 5050 r->rem_set()->occupied(), 5051 r->rem_set()->strong_code_roots_list_length(), 5052 next_bitmap->isMarked(r->bottom()), 5053 g1h->is_humongous_reclaim_candidate(region_idx), 5054 obj->is_typeArray() 5055 ); 5056 5057 // Need to clear mark bit of the humongous object if already set. 5058 if (next_bitmap->isMarked(r->bottom())) { 5059 next_bitmap->clear(r->bottom()); 5060 } 5061 do { 5062 HeapRegion* next = g1h->next_region_in_humongous(r); 5063 _freed_bytes += r->used(); 5064 r->set_containing_set(NULL); 5065 _humongous_regions_removed++; 5066 g1h->free_humongous_region(r, _free_region_list, false); 5067 r = next; 5068 } while (r != NULL); 5069 5070 return false; 5071 } 5072 5073 uint humongous_free_count() { 5074 return _humongous_regions_removed; 5075 } 5076 5077 size_t bytes_freed() const { 5078 return _freed_bytes; 5079 } 5080 }; 5081 5082 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 5083 assert_at_safepoint(true); 5084 5085 if (!G1EagerReclaimHumongousObjects || 5086 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 5087 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 5088 return; 5089 } 5090 5091 double start_time = os::elapsedTime(); 5092 5093 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 5094 5095 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 5096 heap_region_iterate(&cl); 5097 5098 remove_from_old_sets(0, cl.humongous_free_count()); 5099 5100 G1HRPrinter* hrp = hr_printer(); 5101 if (hrp->is_active()) { 5102 FreeRegionListIterator iter(&local_cleanup_list); 5103 while (iter.more_available()) { 5104 HeapRegion* hr = iter.get_next(); 5105 hrp->cleanup(hr); 5106 } 5107 } 5108 5109 prepend_to_freelist(&local_cleanup_list); 5110 decrement_summary_bytes(cl.bytes_freed()); 5111 5112 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 5113 cl.humongous_free_count()); 5114 } 5115 5116 // This routine is similar to the above but does not record 5117 // any policy statistics or update free lists; we are abandoning 5118 // the current incremental collection set in preparation of a 5119 // full collection. After the full GC we will start to build up 5120 // the incremental collection set again. 5121 // This is only called when we're doing a full collection 5122 // and is immediately followed by the tearing down of the young list. 5123 5124 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 5125 HeapRegion* cur = cs_head; 5126 5127 while (cur != NULL) { 5128 HeapRegion* next = cur->next_in_collection_set(); 5129 assert(cur->in_collection_set(), "bad CS"); 5130 cur->set_next_in_collection_set(NULL); 5131 clear_in_cset(cur); 5132 cur->set_young_index_in_cset(-1); 5133 cur = next; 5134 } 5135 } 5136 5137 void G1CollectedHeap::set_free_regions_coming() { 5138 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming"); 5139 5140 assert(!free_regions_coming(), "pre-condition"); 5141 _free_regions_coming = true; 5142 } 5143 5144 void G1CollectedHeap::reset_free_regions_coming() { 5145 assert(free_regions_coming(), "pre-condition"); 5146 5147 { 5148 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5149 _free_regions_coming = false; 5150 SecondaryFreeList_lock->notify_all(); 5151 } 5152 5153 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming"); 5154 } 5155 5156 void G1CollectedHeap::wait_while_free_regions_coming() { 5157 // Most of the time we won't have to wait, so let's do a quick test 5158 // first before we take the lock. 5159 if (!free_regions_coming()) { 5160 return; 5161 } 5162 5163 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions"); 5164 5165 { 5166 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5167 while (free_regions_coming()) { 5168 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 5169 } 5170 } 5171 5172 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions"); 5173 } 5174 5175 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 5176 return _allocator->is_retained_old_region(hr); 5177 } 5178 5179 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 5180 _young_list->push_region(hr); 5181 } 5182 5183 class NoYoungRegionsClosure: public HeapRegionClosure { 5184 private: 5185 bool _success; 5186 public: 5187 NoYoungRegionsClosure() : _success(true) { } 5188 bool doHeapRegion(HeapRegion* r) { 5189 if (r->is_young()) { 5190 log_info(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 5191 p2i(r->bottom()), p2i(r->end())); 5192 _success = false; 5193 } 5194 return false; 5195 } 5196 bool success() { return _success; } 5197 }; 5198 5199 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 5200 bool ret = _young_list->check_list_empty(check_sample); 5201 5202 if (check_heap) { 5203 NoYoungRegionsClosure closure; 5204 heap_region_iterate(&closure); 5205 ret = ret && closure.success(); 5206 } 5207 5208 return ret; 5209 } 5210 5211 class TearDownRegionSetsClosure : public HeapRegionClosure { 5212 private: 5213 HeapRegionSet *_old_set; 5214 5215 public: 5216 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 5217 5218 bool doHeapRegion(HeapRegion* r) { 5219 if (r->is_old()) { 5220 _old_set->remove(r); 5221 } else { 5222 // We ignore free regions, we'll empty the free list afterwards. 5223 // We ignore young regions, we'll empty the young list afterwards. 5224 // We ignore humongous regions, we're not tearing down the 5225 // humongous regions set. 5226 assert(r->is_free() || r->is_young() || r->is_humongous(), 5227 "it cannot be another type"); 5228 } 5229 return false; 5230 } 5231 5232 ~TearDownRegionSetsClosure() { 5233 assert(_old_set->is_empty(), "post-condition"); 5234 } 5235 }; 5236 5237 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 5238 assert_at_safepoint(true /* should_be_vm_thread */); 5239 5240 if (!free_list_only) { 5241 TearDownRegionSetsClosure cl(&_old_set); 5242 heap_region_iterate(&cl); 5243 5244 // Note that emptying the _young_list is postponed and instead done as 5245 // the first step when rebuilding the regions sets again. The reason for 5246 // this is that during a full GC string deduplication needs to know if 5247 // a collected region was young or old when the full GC was initiated. 5248 } 5249 _hrm.remove_all_free_regions(); 5250 } 5251 5252 void G1CollectedHeap::increase_used(size_t bytes) { 5253 _summary_bytes_used += bytes; 5254 } 5255 5256 void G1CollectedHeap::decrease_used(size_t bytes) { 5257 assert(_summary_bytes_used >= bytes, 5258 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 5259 _summary_bytes_used, bytes); 5260 _summary_bytes_used -= bytes; 5261 } 5262 5263 void G1CollectedHeap::set_used(size_t bytes) { 5264 _summary_bytes_used = bytes; 5265 } 5266 5267 class RebuildRegionSetsClosure : public HeapRegionClosure { 5268 private: 5269 bool _free_list_only; 5270 HeapRegionSet* _old_set; 5271 HeapRegionManager* _hrm; 5272 size_t _total_used; 5273 5274 public: 5275 RebuildRegionSetsClosure(bool free_list_only, 5276 HeapRegionSet* old_set, HeapRegionManager* hrm) : 5277 _free_list_only(free_list_only), 5278 _old_set(old_set), _hrm(hrm), _total_used(0) { 5279 assert(_hrm->num_free_regions() == 0, "pre-condition"); 5280 if (!free_list_only) { 5281 assert(_old_set->is_empty(), "pre-condition"); 5282 } 5283 } 5284 5285 bool doHeapRegion(HeapRegion* r) { 5286 if (r->is_empty()) { 5287 // Add free regions to the free list 5288 r->set_free(); 5289 r->set_allocation_context(AllocationContext::system()); 5290 _hrm->insert_into_free_list(r); 5291 } else if (!_free_list_only) { 5292 assert(!r->is_young(), "we should not come across young regions"); 5293 5294 if (r->is_humongous()) { 5295 // We ignore humongous regions. We left the humongous set unchanged. 5296 } else { 5297 // Objects that were compacted would have ended up on regions 5298 // that were previously old or free. Archive regions (which are 5299 // old) will not have been touched. 5300 assert(r->is_free() || r->is_old(), "invariant"); 5301 // We now consider them old, so register as such. Leave 5302 // archive regions set that way, however, while still adding 5303 // them to the old set. 5304 if (!r->is_archive()) { 5305 r->set_old(); 5306 } 5307 _old_set->add(r); 5308 } 5309 _total_used += r->used(); 5310 } 5311 5312 return false; 5313 } 5314 5315 size_t total_used() { 5316 return _total_used; 5317 } 5318 }; 5319 5320 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 5321 assert_at_safepoint(true /* should_be_vm_thread */); 5322 5323 if (!free_list_only) { 5324 _young_list->empty_list(); 5325 } 5326 5327 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 5328 heap_region_iterate(&cl); 5329 5330 if (!free_list_only) { 5331 set_used(cl.total_used()); 5332 if (_archive_allocator != NULL) { 5333 _archive_allocator->clear_used(); 5334 } 5335 } 5336 assert(used_unlocked() == recalculate_used(), 5337 "inconsistent used_unlocked(), " 5338 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 5339 used_unlocked(), recalculate_used()); 5340 } 5341 5342 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 5343 _refine_cte_cl->set_concurrent(concurrent); 5344 } 5345 5346 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 5347 HeapRegion* hr = heap_region_containing(p); 5348 return hr->is_in(p); 5349 } 5350 5351 // Methods for the mutator alloc region 5352 5353 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 5354 bool force) { 5355 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 5356 assert(!force || g1_policy()->can_expand_young_list(), 5357 "if force is true we should be able to expand the young list"); 5358 bool young_list_full = g1_policy()->is_young_list_full(); 5359 if (force || !young_list_full) { 5360 HeapRegion* new_alloc_region = new_region(word_size, 5361 false /* is_old */, 5362 false /* do_expand */); 5363 if (new_alloc_region != NULL) { 5364 set_region_short_lived_locked(new_alloc_region); 5365 _hr_printer.alloc(new_alloc_region, young_list_full); 5366 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 5367 return new_alloc_region; 5368 } 5369 } 5370 return NULL; 5371 } 5372 5373 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 5374 size_t allocated_bytes) { 5375 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 5376 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 5377 5378 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 5379 increase_used(allocated_bytes); 5380 _hr_printer.retire(alloc_region); 5381 // We update the eden sizes here, when the region is retired, 5382 // instead of when it's allocated, since this is the point that its 5383 // used space has been recored in _summary_bytes_used. 5384 g1mm()->update_eden_size(); 5385 } 5386 5387 // Methods for the GC alloc regions 5388 5389 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 5390 uint count, 5391 InCSetState dest) { 5392 assert(FreeList_lock->owned_by_self(), "pre-condition"); 5393 5394 assert(dest.is_old() || dest.is_young(), "We should only get here with old or young (survivor) as destination."); 5395 5396 if (dest.is_old() || count < g1_policy()->max_survivor_regions()) { 5397 const bool is_survivor = (dest.is_young()); 5398 HeapRegion* new_alloc_region = new_region(word_size, 5399 !is_survivor, 5400 true /* do_expand */); 5401 if (new_alloc_region != NULL) { 5402 // We really only need to do this for old regions given that we 5403 // should never scan survivors. But it doesn't hurt to do it 5404 // for survivors too. 5405 new_alloc_region->record_timestamp(); 5406 if (is_survivor) { 5407 new_alloc_region->set_survivor(); 5408 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 5409 } else { 5410 new_alloc_region->set_old(); 5411 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 5412 } 5413 _hr_printer.alloc(new_alloc_region); 5414 bool during_im = collector_state()->during_initial_mark_pause(); 5415 new_alloc_region->note_start_of_copying(during_im); 5416 return new_alloc_region; 5417 } 5418 } 5419 return NULL; 5420 } 5421 5422 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 5423 size_t allocated_bytes, 5424 InCSetState dest) { 5425 bool during_im = collector_state()->during_initial_mark_pause(); 5426 alloc_region->note_end_of_copying(during_im); 5427 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 5428 if (dest.is_young()) { 5429 young_list()->add_survivor_region(alloc_region); 5430 } else { 5431 _old_set.add(alloc_region); 5432 } 5433 _hr_printer.retire(alloc_region); 5434 } 5435 5436 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 5437 bool expanded = false; 5438 uint index = _hrm.find_highest_free(&expanded); 5439 5440 if (index != G1_NO_HRM_INDEX) { 5441 if (expanded) { 5442 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 5443 HeapRegion::GrainWords * HeapWordSize); 5444 } 5445 _hrm.allocate_free_regions_starting_at(index, 1); 5446 return region_at(index); 5447 } 5448 return NULL; 5449 } 5450 5451 // Optimized nmethod scanning 5452 5453 class RegisterNMethodOopClosure: public OopClosure { 5454 G1CollectedHeap* _g1h; 5455 nmethod* _nm; 5456 5457 template <class T> void do_oop_work(T* p) { 5458 T heap_oop = oopDesc::load_heap_oop(p); 5459 if (!oopDesc::is_null(heap_oop)) { 5460 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 5461 HeapRegion* hr = _g1h->heap_region_containing(obj); 5462 assert(!hr->is_continues_humongous(), 5463 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 5464 " starting at " HR_FORMAT, 5465 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 5466 5467 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 5468 hr->add_strong_code_root_locked(_nm); 5469 } 5470 } 5471 5472 public: 5473 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 5474 _g1h(g1h), _nm(nm) {} 5475 5476 void do_oop(oop* p) { do_oop_work(p); } 5477 void do_oop(narrowOop* p) { do_oop_work(p); } 5478 }; 5479 5480 class UnregisterNMethodOopClosure: public OopClosure { 5481 G1CollectedHeap* _g1h; 5482 nmethod* _nm; 5483 5484 template <class T> void do_oop_work(T* p) { 5485 T heap_oop = oopDesc::load_heap_oop(p); 5486 if (!oopDesc::is_null(heap_oop)) { 5487 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 5488 HeapRegion* hr = _g1h->heap_region_containing(obj); 5489 assert(!hr->is_continues_humongous(), 5490 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 5491 " starting at " HR_FORMAT, 5492 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 5493 5494 hr->remove_strong_code_root(_nm); 5495 } 5496 } 5497 5498 public: 5499 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 5500 _g1h(g1h), _nm(nm) {} 5501 5502 void do_oop(oop* p) { do_oop_work(p); } 5503 void do_oop(narrowOop* p) { do_oop_work(p); } 5504 }; 5505 5506 void G1CollectedHeap::register_nmethod(nmethod* nm) { 5507 CollectedHeap::register_nmethod(nm); 5508 5509 guarantee(nm != NULL, "sanity"); 5510 RegisterNMethodOopClosure reg_cl(this, nm); 5511 nm->oops_do(®_cl); 5512 } 5513 5514 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 5515 CollectedHeap::unregister_nmethod(nm); 5516 5517 guarantee(nm != NULL, "sanity"); 5518 UnregisterNMethodOopClosure reg_cl(this, nm); 5519 nm->oops_do(®_cl, true); 5520 } 5521 5522 void G1CollectedHeap::purge_code_root_memory() { 5523 double purge_start = os::elapsedTime(); 5524 G1CodeRootSet::purge(); 5525 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 5526 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 5527 } 5528 5529 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 5530 G1CollectedHeap* _g1h; 5531 5532 public: 5533 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 5534 _g1h(g1h) {} 5535 5536 void do_code_blob(CodeBlob* cb) { 5537 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 5538 if (nm == NULL) { 5539 return; 5540 } 5541 5542 if (ScavengeRootsInCode) { 5543 _g1h->register_nmethod(nm); 5544 } 5545 } 5546 }; 5547 5548 void G1CollectedHeap::rebuild_strong_code_roots() { 5549 RebuildStrongCodeRootClosure blob_cl(this); 5550 CodeCache::blobs_do(&blob_cl); 5551 }