1 /* 2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #if !defined(__clang_major__) && defined(__GNUC__) 26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information. 27 #define ATTRIBUTE_PRINTF(x,y) 28 #endif 29 30 #include "precompiled.hpp" 31 #include "classfile/metadataOnStackMark.hpp" 32 #include "classfile/stringTable.hpp" 33 #include "code/codeCache.hpp" 34 #include "code/icBuffer.hpp" 35 #include "gc_implementation/g1/bufferingOopClosure.hpp" 36 #include "gc_implementation/g1/concurrentG1Refine.hpp" 37 #include "gc_implementation/g1/concurrentG1RefineThread.hpp" 38 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 39 #include "gc_implementation/g1/g1AllocRegion.inline.hpp" 40 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 41 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 42 #include "gc_implementation/g1/g1ErgoVerbose.hpp" 43 #include "gc_implementation/g1/g1EvacFailure.hpp" 44 #include "gc_implementation/g1/g1GCPhaseTimes.hpp" 45 #include "gc_implementation/g1/g1Log.hpp" 46 #include "gc_implementation/g1/g1MarkSweep.hpp" 47 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 48 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp" 49 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp" 50 #include "gc_implementation/g1/g1RemSet.inline.hpp" 51 #include "gc_implementation/g1/g1RootProcessor.hpp" 52 #include "gc_implementation/g1/g1StringDedup.hpp" 53 #include "gc_implementation/g1/g1YCTypes.hpp" 54 #include "gc_implementation/g1/heapRegion.inline.hpp" 55 #include "gc_implementation/g1/heapRegionRemSet.hpp" 56 #include "gc_implementation/g1/heapRegionSet.inline.hpp" 57 #include "gc_implementation/g1/vm_operations_g1.hpp" 58 #include "gc_implementation/shared/gcHeapSummary.hpp" 59 #include "gc_implementation/shared/gcTimer.hpp" 60 #include "gc_implementation/shared/gcTrace.hpp" 61 #include "gc_implementation/shared/gcTraceTime.hpp" 62 #include "gc_implementation/shared/isGCActiveMark.hpp" 63 #include "memory/allocation.hpp" 64 #include "memory/gcLocker.inline.hpp" 65 #include "memory/generationSpec.hpp" 66 #include "memory/iterator.hpp" 67 #include "memory/referenceProcessor.hpp" 68 #include "oops/oop.inline.hpp" 69 #include "oops/oop.pcgc.inline.hpp" 70 #include "runtime/atomic.inline.hpp" 71 #include "runtime/orderAccess.inline.hpp" 72 #include "runtime/vmThread.hpp" 73 #include "utilities/globalDefinitions.hpp" 74 75 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 76 77 // turn it on so that the contents of the young list (scan-only / 78 // to-be-collected) are printed at "strategic" points before / during 79 // / after the collection --- this is useful for debugging 80 #define YOUNG_LIST_VERBOSE 0 81 // CURRENT STATUS 82 // This file is under construction. Search for "FIXME". 83 84 // INVARIANTS/NOTES 85 // 86 // All allocation activity covered by the G1CollectedHeap interface is 87 // serialized by acquiring the HeapLock. This happens in mem_allocate 88 // and allocate_new_tlab, which are the "entry" points to the 89 // allocation code from the rest of the JVM. (Note that this does not 90 // apply to TLAB allocation, which is not part of this interface: it 91 // is done by clients of this interface.) 92 93 // Local to this file. 94 95 class RefineCardTableEntryClosure: public CardTableEntryClosure { 96 bool _concurrent; 97 public: 98 RefineCardTableEntryClosure() : _concurrent(true) { } 99 100 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 101 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 102 // This path is executed by the concurrent refine or mutator threads, 103 // concurrently, and so we do not care if card_ptr contains references 104 // that point into the collection set. 105 assert(!oops_into_cset, "should be"); 106 107 if (_concurrent && SuspendibleThreadSet::should_yield()) { 108 // Caller will actually yield. 109 return false; 110 } 111 // Otherwise, we finished successfully; return true. 112 return true; 113 } 114 115 void set_concurrent(bool b) { _concurrent = b; } 116 }; 117 118 119 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 120 private: 121 size_t _num_processed; 122 123 public: 124 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { } 125 126 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 127 *card_ptr = CardTableModRefBS::dirty_card_val(); 128 _num_processed++; 129 return true; 130 } 131 132 size_t num_processed() const { return _num_processed; } 133 }; 134 135 YoungList::YoungList(G1CollectedHeap* g1h) : 136 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 137 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 138 guarantee(check_list_empty(false), "just making sure..."); 139 } 140 141 void YoungList::push_region(HeapRegion *hr) { 142 assert(!hr->is_young(), "should not already be young"); 143 assert(hr->get_next_young_region() == NULL, "cause it should!"); 144 145 hr->set_next_young_region(_head); 146 _head = hr; 147 148 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 149 ++_length; 150 } 151 152 void YoungList::add_survivor_region(HeapRegion* hr) { 153 assert(hr->is_survivor(), "should be flagged as survivor region"); 154 assert(hr->get_next_young_region() == NULL, "cause it should!"); 155 156 hr->set_next_young_region(_survivor_head); 157 if (_survivor_head == NULL) { 158 _survivor_tail = hr; 159 } 160 _survivor_head = hr; 161 ++_survivor_length; 162 } 163 164 void YoungList::empty_list(HeapRegion* list) { 165 while (list != NULL) { 166 HeapRegion* next = list->get_next_young_region(); 167 list->set_next_young_region(NULL); 168 list->uninstall_surv_rate_group(); 169 // This is called before a Full GC and all the non-empty / 170 // non-humongous regions at the end of the Full GC will end up as 171 // old anyway. 172 list->set_old(); 173 list = next; 174 } 175 } 176 177 void YoungList::empty_list() { 178 assert(check_list_well_formed(), "young list should be well formed"); 179 180 empty_list(_head); 181 _head = NULL; 182 _length = 0; 183 184 empty_list(_survivor_head); 185 _survivor_head = NULL; 186 _survivor_tail = NULL; 187 _survivor_length = 0; 188 189 _last_sampled_rs_lengths = 0; 190 191 assert(check_list_empty(false), "just making sure..."); 192 } 193 194 bool YoungList::check_list_well_formed() { 195 bool ret = true; 196 197 uint length = 0; 198 HeapRegion* curr = _head; 199 HeapRegion* last = NULL; 200 while (curr != NULL) { 201 if (!curr->is_young()) { 202 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " 203 "incorrectly tagged (y: %d, surv: %d)", 204 curr->bottom(), curr->end(), 205 curr->is_young(), curr->is_survivor()); 206 ret = false; 207 } 208 ++length; 209 last = curr; 210 curr = curr->get_next_young_region(); 211 } 212 ret = ret && (length == _length); 213 214 if (!ret) { 215 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 216 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 217 length, _length); 218 } 219 220 return ret; 221 } 222 223 bool YoungList::check_list_empty(bool check_sample) { 224 bool ret = true; 225 226 if (_length != 0) { 227 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 228 _length); 229 ret = false; 230 } 231 if (check_sample && _last_sampled_rs_lengths != 0) { 232 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 233 ret = false; 234 } 235 if (_head != NULL) { 236 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 237 ret = false; 238 } 239 if (!ret) { 240 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 241 } 242 243 return ret; 244 } 245 246 void 247 YoungList::rs_length_sampling_init() { 248 _sampled_rs_lengths = 0; 249 _curr = _head; 250 } 251 252 bool 253 YoungList::rs_length_sampling_more() { 254 return _curr != NULL; 255 } 256 257 void 258 YoungList::rs_length_sampling_next() { 259 assert( _curr != NULL, "invariant" ); 260 size_t rs_length = _curr->rem_set()->occupied(); 261 262 _sampled_rs_lengths += rs_length; 263 264 // The current region may not yet have been added to the 265 // incremental collection set (it gets added when it is 266 // retired as the current allocation region). 267 if (_curr->in_collection_set()) { 268 // Update the collection set policy information for this region 269 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 270 } 271 272 _curr = _curr->get_next_young_region(); 273 if (_curr == NULL) { 274 _last_sampled_rs_lengths = _sampled_rs_lengths; 275 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 276 } 277 } 278 279 void 280 YoungList::reset_auxilary_lists() { 281 guarantee( is_empty(), "young list should be empty" ); 282 assert(check_list_well_formed(), "young list should be well formed"); 283 284 // Add survivor regions to SurvRateGroup. 285 _g1h->g1_policy()->note_start_adding_survivor_regions(); 286 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 287 288 int young_index_in_cset = 0; 289 for (HeapRegion* curr = _survivor_head; 290 curr != NULL; 291 curr = curr->get_next_young_region()) { 292 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 293 294 // The region is a non-empty survivor so let's add it to 295 // the incremental collection set for the next evacuation 296 // pause. 297 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 298 young_index_in_cset += 1; 299 } 300 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 301 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 302 303 _head = _survivor_head; 304 _length = _survivor_length; 305 if (_survivor_head != NULL) { 306 assert(_survivor_tail != NULL, "cause it shouldn't be"); 307 assert(_survivor_length > 0, "invariant"); 308 _survivor_tail->set_next_young_region(NULL); 309 } 310 311 // Don't clear the survivor list handles until the start of 312 // the next evacuation pause - we need it in order to re-tag 313 // the survivor regions from this evacuation pause as 'young' 314 // at the start of the next. 315 316 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 317 318 assert(check_list_well_formed(), "young list should be well formed"); 319 } 320 321 void YoungList::print() { 322 HeapRegion* lists[] = {_head, _survivor_head}; 323 const char* names[] = {"YOUNG", "SURVIVOR"}; 324 325 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) { 326 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 327 HeapRegion *curr = lists[list]; 328 if (curr == NULL) 329 gclog_or_tty->print_cr(" empty"); 330 while (curr != NULL) { 331 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d", 332 HR_FORMAT_PARAMS(curr), 333 curr->prev_top_at_mark_start(), 334 curr->next_top_at_mark_start(), 335 curr->age_in_surv_rate_group_cond()); 336 curr = curr->get_next_young_region(); 337 } 338 } 339 340 gclog_or_tty->cr(); 341 } 342 343 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 344 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 345 } 346 347 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 348 // The from card cache is not the memory that is actually committed. So we cannot 349 // take advantage of the zero_filled parameter. 350 reset_from_card_cache(start_idx, num_regions); 351 } 352 353 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 354 { 355 // Claim the right to put the region on the dirty cards region list 356 // by installing a self pointer. 357 HeapRegion* next = hr->get_next_dirty_cards_region(); 358 if (next == NULL) { 359 HeapRegion* res = (HeapRegion*) 360 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 361 NULL); 362 if (res == NULL) { 363 HeapRegion* head; 364 do { 365 // Put the region to the dirty cards region list. 366 head = _dirty_cards_region_list; 367 next = (HeapRegion*) 368 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 369 if (next == head) { 370 assert(hr->get_next_dirty_cards_region() == hr, 371 "hr->get_next_dirty_cards_region() != hr"); 372 if (next == NULL) { 373 // The last region in the list points to itself. 374 hr->set_next_dirty_cards_region(hr); 375 } else { 376 hr->set_next_dirty_cards_region(next); 377 } 378 } 379 } while (next != head); 380 } 381 } 382 } 383 384 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 385 { 386 HeapRegion* head; 387 HeapRegion* hr; 388 do { 389 head = _dirty_cards_region_list; 390 if (head == NULL) { 391 return NULL; 392 } 393 HeapRegion* new_head = head->get_next_dirty_cards_region(); 394 if (head == new_head) { 395 // The last region. 396 new_head = NULL; 397 } 398 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 399 head); 400 } while (hr != head); 401 assert(hr != NULL, "invariant"); 402 hr->set_next_dirty_cards_region(NULL); 403 return hr; 404 } 405 406 #ifdef ASSERT 407 // A region is added to the collection set as it is retired 408 // so an address p can point to a region which will be in the 409 // collection set but has not yet been retired. This method 410 // therefore is only accurate during a GC pause after all 411 // regions have been retired. It is used for debugging 412 // to check if an nmethod has references to objects that can 413 // be move during a partial collection. Though it can be 414 // inaccurate, it is sufficient for G1 because the conservative 415 // implementation of is_scavengable() for G1 will indicate that 416 // all nmethods must be scanned during a partial collection. 417 bool G1CollectedHeap::is_in_partial_collection(const void* p) { 418 if (p == NULL) { 419 return false; 420 } 421 return heap_region_containing(p)->in_collection_set(); 422 } 423 #endif 424 425 // Returns true if the reference points to an object that 426 // can move in an incremental collection. 427 bool G1CollectedHeap::is_scavengable(const void* p) { 428 HeapRegion* hr = heap_region_containing(p); 429 return !hr->is_humongous(); 430 } 431 432 // Private class members. 433 434 G1CollectedHeap* G1CollectedHeap::_g1h; 435 436 // Private methods. 437 438 HeapRegion* 439 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 440 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 441 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 442 if (!_secondary_free_list.is_empty()) { 443 if (G1ConcRegionFreeingVerbose) { 444 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 445 "secondary_free_list has %u entries", 446 _secondary_free_list.length()); 447 } 448 // It looks as if there are free regions available on the 449 // secondary_free_list. Let's move them to the free_list and try 450 // again to allocate from it. 451 append_secondary_free_list(); 452 453 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 454 "empty we should have moved at least one entry to the free_list"); 455 HeapRegion* res = _hrm.allocate_free_region(is_old); 456 if (G1ConcRegionFreeingVerbose) { 457 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 458 "allocated "HR_FORMAT" from secondary_free_list", 459 HR_FORMAT_PARAMS(res)); 460 } 461 return res; 462 } 463 464 // Wait here until we get notified either when (a) there are no 465 // more free regions coming or (b) some regions have been moved on 466 // the secondary_free_list. 467 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 468 } 469 470 if (G1ConcRegionFreeingVerbose) { 471 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 472 "could not allocate from secondary_free_list"); 473 } 474 return NULL; 475 } 476 477 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 478 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 479 "the only time we use this to allocate a humongous region is " 480 "when we are allocating a single humongous region"); 481 482 HeapRegion* res; 483 if (G1StressConcRegionFreeing) { 484 if (!_secondary_free_list.is_empty()) { 485 if (G1ConcRegionFreeingVerbose) { 486 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 487 "forced to look at the secondary_free_list"); 488 } 489 res = new_region_try_secondary_free_list(is_old); 490 if (res != NULL) { 491 return res; 492 } 493 } 494 } 495 496 res = _hrm.allocate_free_region(is_old); 497 498 if (res == NULL) { 499 if (G1ConcRegionFreeingVerbose) { 500 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 501 "res == NULL, trying the secondary_free_list"); 502 } 503 res = new_region_try_secondary_free_list(is_old); 504 } 505 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 506 // Currently, only attempts to allocate GC alloc regions set 507 // do_expand to true. So, we should only reach here during a 508 // safepoint. If this assumption changes we might have to 509 // reconsider the use of _expand_heap_after_alloc_failure. 510 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 511 512 ergo_verbose1(ErgoHeapSizing, 513 "attempt heap expansion", 514 ergo_format_reason("region allocation request failed") 515 ergo_format_byte("allocation request"), 516 word_size * HeapWordSize); 517 if (expand(word_size * HeapWordSize)) { 518 // Given that expand() succeeded in expanding the heap, and we 519 // always expand the heap by an amount aligned to the heap 520 // region size, the free list should in theory not be empty. 521 // In either case allocate_free_region() will check for NULL. 522 res = _hrm.allocate_free_region(is_old); 523 } else { 524 _expand_heap_after_alloc_failure = false; 525 } 526 } 527 return res; 528 } 529 530 HeapWord* 531 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 532 uint num_regions, 533 size_t word_size, 534 AllocationContext_t context) { 535 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 536 assert(is_humongous(word_size), "word_size should be humongous"); 537 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 538 539 // Index of last region in the series + 1. 540 uint last = first + num_regions; 541 542 // We need to initialize the region(s) we just discovered. This is 543 // a bit tricky given that it can happen concurrently with 544 // refinement threads refining cards on these regions and 545 // potentially wanting to refine the BOT as they are scanning 546 // those cards (this can happen shortly after a cleanup; see CR 547 // 6991377). So we have to set up the region(s) carefully and in 548 // a specific order. 549 550 // The word size sum of all the regions we will allocate. 551 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 552 assert(word_size <= word_size_sum, "sanity"); 553 554 // This will be the "starts humongous" region. 555 HeapRegion* first_hr = region_at(first); 556 // The header of the new object will be placed at the bottom of 557 // the first region. 558 HeapWord* new_obj = first_hr->bottom(); 559 // This will be the new end of the first region in the series that 560 // should also match the end of the last region in the series. 561 HeapWord* new_end = new_obj + word_size_sum; 562 // This will be the new top of the first region that will reflect 563 // this allocation. 564 HeapWord* new_top = new_obj + word_size; 565 566 // First, we need to zero the header of the space that we will be 567 // allocating. When we update top further down, some refinement 568 // threads might try to scan the region. By zeroing the header we 569 // ensure that any thread that will try to scan the region will 570 // come across the zero klass word and bail out. 571 // 572 // NOTE: It would not have been correct to have used 573 // CollectedHeap::fill_with_object() and make the space look like 574 // an int array. The thread that is doing the allocation will 575 // later update the object header to a potentially different array 576 // type and, for a very short period of time, the klass and length 577 // fields will be inconsistent. This could cause a refinement 578 // thread to calculate the object size incorrectly. 579 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 580 581 // We will set up the first region as "starts humongous". This 582 // will also update the BOT covering all the regions to reflect 583 // that there is a single object that starts at the bottom of the 584 // first region. 585 first_hr->set_starts_humongous(new_top, new_end); 586 first_hr->set_allocation_context(context); 587 // Then, if there are any, we will set up the "continues 588 // humongous" regions. 589 HeapRegion* hr = NULL; 590 for (uint i = first + 1; i < last; ++i) { 591 hr = region_at(i); 592 hr->set_continues_humongous(first_hr); 593 hr->set_allocation_context(context); 594 } 595 // If we have "continues humongous" regions (hr != NULL), then the 596 // end of the last one should match new_end. 597 assert(hr == NULL || hr->end() == new_end, "sanity"); 598 599 // Up to this point no concurrent thread would have been able to 600 // do any scanning on any region in this series. All the top 601 // fields still point to bottom, so the intersection between 602 // [bottom,top] and [card_start,card_end] will be empty. Before we 603 // update the top fields, we'll do a storestore to make sure that 604 // no thread sees the update to top before the zeroing of the 605 // object header and the BOT initialization. 606 OrderAccess::storestore(); 607 608 // Now that the BOT and the object header have been initialized, 609 // we can update top of the "starts humongous" region. 610 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 611 "new_top should be in this region"); 612 first_hr->set_top(new_top); 613 if (_hr_printer.is_active()) { 614 HeapWord* bottom = first_hr->bottom(); 615 HeapWord* end = first_hr->orig_end(); 616 if ((first + 1) == last) { 617 // the series has a single humongous region 618 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 619 } else { 620 // the series has more than one humongous regions 621 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 622 } 623 } 624 625 // Now, we will update the top fields of the "continues humongous" 626 // regions. The reason we need to do this is that, otherwise, 627 // these regions would look empty and this will confuse parts of 628 // G1. For example, the code that looks for a consecutive number 629 // of empty regions will consider them empty and try to 630 // re-allocate them. We can extend is_empty() to also include 631 // !is_continues_humongous(), but it is easier to just update the top 632 // fields here. The way we set top for all regions (i.e., top == 633 // end for all regions but the last one, top == new_top for the 634 // last one) is actually used when we will free up the humongous 635 // region in free_humongous_region(). 636 hr = NULL; 637 for (uint i = first + 1; i < last; ++i) { 638 hr = region_at(i); 639 if ((i + 1) == last) { 640 // last continues humongous region 641 assert(hr->bottom() < new_top && new_top <= hr->end(), 642 "new_top should fall on this region"); 643 hr->set_top(new_top); 644 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 645 } else { 646 // not last one 647 assert(new_top > hr->end(), "new_top should be above this region"); 648 hr->set_top(hr->end()); 649 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 650 } 651 } 652 // If we have continues humongous regions (hr != NULL), then the 653 // end of the last one should match new_end and its top should 654 // match new_top. 655 assert(hr == NULL || 656 (hr->end() == new_end && hr->top() == new_top), "sanity"); 657 check_bitmaps("Humongous Region Allocation", first_hr); 658 659 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 660 _allocator->increase_used(first_hr->used()); 661 _humongous_set.add(first_hr); 662 663 return new_obj; 664 } 665 666 // If could fit into free regions w/o expansion, try. 667 // Otherwise, if can expand, do so. 668 // Otherwise, if using ex regions might help, try with ex given back. 669 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 670 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 671 672 verify_region_sets_optional(); 673 674 uint first = G1_NO_HRM_INDEX; 675 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords); 676 677 if (obj_regions == 1) { 678 // Only one region to allocate, try to use a fast path by directly allocating 679 // from the free lists. Do not try to expand here, we will potentially do that 680 // later. 681 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 682 if (hr != NULL) { 683 first = hr->hrm_index(); 684 } 685 } else { 686 // We can't allocate humongous regions spanning more than one region while 687 // cleanupComplete() is running, since some of the regions we find to be 688 // empty might not yet be added to the free list. It is not straightforward 689 // to know in which list they are on so that we can remove them. We only 690 // need to do this if we need to allocate more than one region to satisfy the 691 // current humongous allocation request. If we are only allocating one region 692 // we use the one-region region allocation code (see above), that already 693 // potentially waits for regions from the secondary free list. 694 wait_while_free_regions_coming(); 695 append_secondary_free_list_if_not_empty_with_lock(); 696 697 // Policy: Try only empty regions (i.e. already committed first). Maybe we 698 // are lucky enough to find some. 699 first = _hrm.find_contiguous_only_empty(obj_regions); 700 if (first != G1_NO_HRM_INDEX) { 701 _hrm.allocate_free_regions_starting_at(first, obj_regions); 702 } 703 } 704 705 if (first == G1_NO_HRM_INDEX) { 706 // Policy: We could not find enough regions for the humongous object in the 707 // free list. Look through the heap to find a mix of free and uncommitted regions. 708 // If so, try expansion. 709 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 710 if (first != G1_NO_HRM_INDEX) { 711 // We found something. Make sure these regions are committed, i.e. expand 712 // the heap. Alternatively we could do a defragmentation GC. 713 ergo_verbose1(ErgoHeapSizing, 714 "attempt heap expansion", 715 ergo_format_reason("humongous allocation request failed") 716 ergo_format_byte("allocation request"), 717 word_size * HeapWordSize); 718 719 _hrm.expand_at(first, obj_regions); 720 g1_policy()->record_new_heap_size(num_regions()); 721 722 #ifdef ASSERT 723 for (uint i = first; i < first + obj_regions; ++i) { 724 HeapRegion* hr = region_at(i); 725 assert(hr->is_free(), "sanity"); 726 assert(hr->is_empty(), "sanity"); 727 assert(is_on_master_free_list(hr), "sanity"); 728 } 729 #endif 730 _hrm.allocate_free_regions_starting_at(first, obj_regions); 731 } else { 732 // Policy: Potentially trigger a defragmentation GC. 733 } 734 } 735 736 HeapWord* result = NULL; 737 if (first != G1_NO_HRM_INDEX) { 738 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 739 word_size, context); 740 assert(result != NULL, "it should always return a valid result"); 741 742 // A successful humongous object allocation changes the used space 743 // information of the old generation so we need to recalculate the 744 // sizes and update the jstat counters here. 745 g1mm()->update_sizes(); 746 } 747 748 verify_region_sets_optional(); 749 750 return result; 751 } 752 753 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 754 assert_heap_not_locked_and_not_at_safepoint(); 755 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 756 757 uint dummy_gc_count_before; 758 uint dummy_gclocker_retry_count = 0; 759 uint gc_attempts = 1; 760 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count, &gc_attempts); 761 } 762 763 HeapWord* 764 G1CollectedHeap::mem_allocate(size_t word_size, 765 bool* gc_overhead_limit_was_exceeded) { 766 assert_heap_not_locked_and_not_at_safepoint(); 767 768 // Loop until the allocation is satisfied, or unsatisfied after GC. 769 for (uint try_count = 1, gclocker_retry_count = 0, gc_attempt = 1; /* we'll return */; try_count += 1) { 770 uint gc_count_before; 771 772 HeapWord* result = NULL; 773 if (!is_humongous(word_size)) { 774 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count, &gc_attempt); 775 } else { 776 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count, &gc_attempt); 777 } 778 if (result != NULL) { 779 return result; 780 } 781 782 // Create the garbage collection operation... 783 VM_G1CollectForAllocation op(gc_count_before, word_size, gc_attempt++); 784 op.set_allocation_context(AllocationContext::current()); 785 786 // ...and get the VM thread to execute it. 787 VMThread::execute(&op); 788 789 if (op.prologue_succeeded() && op.pause_succeeded()) { 790 // If the operation was successful we'll return the result even 791 // if it is NULL. If the allocation attempt failed immediately 792 // after a Full GC, it's unlikely we'll be able to allocate now. 793 HeapWord* result = op.result(); 794 if (result != NULL && !is_humongous(word_size)) { 795 // Allocations that take place on VM operations do not do any 796 // card dirtying and we have to do it here. We only have to do 797 // this for non-humongous allocations, though. 798 dirty_young_block(result, word_size); 799 } 800 return result; 801 } else { 802 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 803 return NULL; 804 } 805 assert(op.result() == NULL, 806 "the result should be NULL if the VM op did not succeed"); 807 } 808 809 // Give a warning if we seem to be looping forever. 810 if ((QueuedAllocationWarningCount > 0) && 811 (try_count % QueuedAllocationWarningCount == 0)) { 812 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 813 } 814 } 815 816 ShouldNotReachHere(); 817 return NULL; 818 } 819 820 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 821 AllocationContext_t context, 822 uint* gc_count_before_ret, 823 uint* gclocker_retry_count_ret, 824 uint* gc_attempt) { 825 // Make sure you read the note in attempt_allocation_humongous(). 826 827 assert_heap_not_locked_and_not_at_safepoint(); 828 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 829 "be called for humongous allocation requests"); 830 831 // We should only get here after the first-level allocation attempt 832 // (attempt_allocation()) failed to allocate. 833 834 // We will loop until a) we manage to successfully perform the 835 // allocation or b) we successfully schedule a collection which 836 // fails to perform the allocation. b) is the only case when we'll 837 // return NULL. 838 HeapWord* result = NULL; 839 for (int try_count = 1; /* we'll return */; try_count += 1) { 840 bool should_try_gc; 841 uint gc_count_before; 842 843 { 844 MutexLockerEx x(Heap_lock); 845 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, 846 false /* bot_updates */); 847 if (result != NULL) { 848 return result; 849 } 850 851 // If we reach here, attempt_allocation_locked() above failed to 852 // allocate a new region. So the mutator alloc region should be NULL. 853 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here"); 854 855 if (GC_locker::is_active_and_needs_gc()) { 856 if (g1_policy()->can_expand_young_list()) { 857 // No need for an ergo verbose message here, 858 // can_expand_young_list() does this when it returns true. 859 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size, 860 false /* bot_updates */); 861 if (result != NULL) { 862 return result; 863 } 864 } 865 should_try_gc = false; 866 } else { 867 // The GCLocker may not be active but the GCLocker initiated 868 // GC may not yet have been performed (GCLocker::needs_gc() 869 // returns true). In this case we do not try this GC and 870 // wait until the GCLocker initiated GC is performed, and 871 // then retry the allocation. 872 if (GC_locker::needs_gc()) { 873 should_try_gc = false; 874 } else { 875 // Read the GC count while still holding the Heap_lock. 876 gc_count_before = total_collections(); 877 should_try_gc = true; 878 } 879 } 880 } 881 882 if (should_try_gc) { 883 bool succeeded; 884 result = do_collection_pause(word_size, gc_count_before, &succeeded, 885 GCCause::_g1_inc_collection_pause, *gc_attempt); 886 *gc_attempt += 1; 887 if (result != NULL) { 888 assert(succeeded, "only way to get back a non-NULL result"); 889 return result; 890 } 891 892 if (succeeded) { 893 // If we get here we successfully scheduled a collection which 894 // failed to allocate. No point in trying to allocate 895 // further. We'll just return NULL. 896 MutexLockerEx x(Heap_lock); 897 *gc_count_before_ret = total_collections(); 898 return NULL; 899 } 900 } else { 901 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 902 MutexLockerEx x(Heap_lock); 903 *gc_count_before_ret = total_collections(); 904 return NULL; 905 } 906 // The GCLocker is either active or the GCLocker initiated 907 // GC has not yet been performed. Stall until it is and 908 // then retry the allocation. 909 GC_locker::stall_until_clear(); 910 (*gclocker_retry_count_ret) += 1; 911 } 912 913 // We can reach here if we were unsuccessful in scheduling a 914 // collection (because another thread beat us to it) or if we were 915 // stalled due to the GC locker. In either can we should retry the 916 // allocation attempt in case another thread successfully 917 // performed a collection and reclaimed enough space. We do the 918 // first attempt (without holding the Heap_lock) here and the 919 // follow-on attempt will be at the start of the next loop 920 // iteration (after taking the Heap_lock). 921 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size, 922 false /* bot_updates */); 923 if (result != NULL) { 924 return result; 925 } 926 927 // Give a warning if we seem to be looping forever. 928 if ((QueuedAllocationWarningCount > 0) && 929 (try_count % QueuedAllocationWarningCount == 0)) { 930 warning("G1CollectedHeap::attempt_allocation_slow() " 931 "retries %d times", try_count); 932 } 933 } 934 935 ShouldNotReachHere(); 936 return NULL; 937 } 938 939 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 940 uint* gc_count_before_ret, 941 uint* gclocker_retry_count_ret, 942 uint* gc_attempt) { 943 // The structure of this method has a lot of similarities to 944 // attempt_allocation_slow(). The reason these two were not merged 945 // into a single one is that such a method would require several "if 946 // allocation is not humongous do this, otherwise do that" 947 // conditional paths which would obscure its flow. In fact, an early 948 // version of this code did use a unified method which was harder to 949 // follow and, as a result, it had subtle bugs that were hard to 950 // track down. So keeping these two methods separate allows each to 951 // be more readable. It will be good to keep these two in sync as 952 // much as possible. 953 954 assert_heap_not_locked_and_not_at_safepoint(); 955 assert(is_humongous(word_size), "attempt_allocation_humongous() " 956 "should only be called for humongous allocations"); 957 958 // Humongous objects can exhaust the heap quickly, so we should check if we 959 // need to start a marking cycle at each humongous object allocation. We do 960 // the check before we do the actual allocation. The reason for doing it 961 // before the allocation is that we avoid having to keep track of the newly 962 // allocated memory while we do a GC. 963 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 964 word_size)) { 965 collect(GCCause::_g1_humongous_allocation); 966 } 967 968 // We will loop until a) we manage to successfully perform the 969 // allocation or b) we successfully schedule a collection which 970 // fails to perform the allocation. b) is the only case when we'll 971 // return NULL. 972 HeapWord* result = NULL; 973 for (int try_count = 1; /* we'll return */; try_count += 1) { 974 bool should_try_gc; 975 uint gc_count_before; 976 977 { 978 MutexLockerEx x(Heap_lock); 979 980 // Given that humongous objects are not allocated in young 981 // regions, we'll first try to do the allocation without doing a 982 // collection hoping that there's enough space in the heap. 983 result = humongous_obj_allocate(word_size, AllocationContext::current()); 984 if (result != NULL) { 985 return result; 986 } 987 988 if (GC_locker::is_active_and_needs_gc()) { 989 should_try_gc = false; 990 } else { 991 // The GCLocker may not be active but the GCLocker initiated 992 // GC may not yet have been performed (GCLocker::needs_gc() 993 // returns true). In this case we do not try this GC and 994 // wait until the GCLocker initiated GC is performed, and 995 // then retry the allocation. 996 if (GC_locker::needs_gc()) { 997 should_try_gc = false; 998 } else { 999 // Read the GC count while still holding the Heap_lock. 1000 gc_count_before = total_collections(); 1001 should_try_gc = true; 1002 } 1003 } 1004 } 1005 1006 if (should_try_gc) { 1007 // If we failed to allocate the humongous object, we should try to 1008 // do a collection pause (if we're allowed) in case it reclaims 1009 // enough space for the allocation to succeed after the pause. 1010 1011 bool succeeded; 1012 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1013 GCCause::_g1_humongous_allocation, *gc_attempt); 1014 *gc_attempt += 1; 1015 if (result != NULL) { 1016 assert(succeeded, "only way to get back a non-NULL result"); 1017 return result; 1018 } 1019 1020 if (succeeded) { 1021 // If we get here we successfully scheduled a collection which 1022 // failed to allocate. No point in trying to allocate 1023 // further. We'll just return NULL. 1024 MutexLockerEx x(Heap_lock); 1025 *gc_count_before_ret = total_collections(); 1026 return NULL; 1027 } 1028 } else { 1029 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1030 MutexLockerEx x(Heap_lock); 1031 *gc_count_before_ret = total_collections(); 1032 return NULL; 1033 } 1034 // The GCLocker is either active or the GCLocker initiated 1035 // GC has not yet been performed. Stall until it is and 1036 // then retry the allocation. 1037 GC_locker::stall_until_clear(); 1038 (*gclocker_retry_count_ret) += 1; 1039 } 1040 1041 // We can reach here if we were unsuccessful in scheduling a 1042 // collection (because another thread beat us to it) or if we were 1043 // stalled due to the GC locker. In either can we should retry the 1044 // allocation attempt in case another thread successfully 1045 // performed a collection and reclaimed enough space. Give a 1046 // warning if we seem to be looping forever. 1047 1048 if ((QueuedAllocationWarningCount > 0) && 1049 (try_count % QueuedAllocationWarningCount == 0)) { 1050 warning("G1CollectedHeap::attempt_allocation_humongous() " 1051 "retries %d times", try_count); 1052 } 1053 } 1054 1055 ShouldNotReachHere(); 1056 return NULL; 1057 } 1058 1059 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1060 AllocationContext_t context, 1061 bool expect_null_mutator_alloc_region) { 1062 assert_at_safepoint(true /* should_be_vm_thread */); 1063 assert(_allocator->mutator_alloc_region(context)->get() == NULL || 1064 !expect_null_mutator_alloc_region, 1065 "the current alloc region was unexpectedly found to be non-NULL"); 1066 1067 if (!is_humongous(word_size)) { 1068 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, 1069 false /* bot_updates */); 1070 } else { 1071 HeapWord* result = humongous_obj_allocate(word_size, context); 1072 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1073 g1_policy()->set_initiate_conc_mark_if_possible(); 1074 } 1075 return result; 1076 } 1077 1078 ShouldNotReachHere(); 1079 } 1080 1081 class PostMCRemSetClearClosure: public HeapRegionClosure { 1082 G1CollectedHeap* _g1h; 1083 ModRefBarrierSet* _mr_bs; 1084 public: 1085 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1086 _g1h(g1h), _mr_bs(mr_bs) {} 1087 1088 bool doHeapRegion(HeapRegion* r) { 1089 HeapRegionRemSet* hrrs = r->rem_set(); 1090 1091 if (r->is_continues_humongous()) { 1092 // We'll assert that the strong code root list and RSet is empty 1093 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1094 assert(hrrs->occupied() == 0, "RSet should be empty"); 1095 return false; 1096 } 1097 1098 _g1h->reset_gc_time_stamps(r); 1099 hrrs->clear(); 1100 // You might think here that we could clear just the cards 1101 // corresponding to the used region. But no: if we leave a dirty card 1102 // in a region we might allocate into, then it would prevent that card 1103 // from being enqueued, and cause it to be missed. 1104 // Re: the performance cost: we shouldn't be doing full GC anyway! 1105 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1106 1107 return false; 1108 } 1109 }; 1110 1111 void G1CollectedHeap::clear_rsets_post_compaction() { 1112 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1113 heap_region_iterate(&rs_clear); 1114 } 1115 1116 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1117 G1CollectedHeap* _g1h; 1118 UpdateRSOopClosure _cl; 1119 int _worker_i; 1120 public: 1121 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) : 1122 _cl(g1->g1_rem_set(), worker_i), 1123 _worker_i(worker_i), 1124 _g1h(g1) 1125 { } 1126 1127 bool doHeapRegion(HeapRegion* r) { 1128 if (!r->is_continues_humongous()) { 1129 _cl.set_from(r); 1130 r->oop_iterate(&_cl); 1131 } 1132 return false; 1133 } 1134 }; 1135 1136 class ParRebuildRSTask: public AbstractGangTask { 1137 G1CollectedHeap* _g1; 1138 HeapRegionClaimer _hrclaimer; 1139 1140 public: 1141 ParRebuildRSTask(G1CollectedHeap* g1) : 1142 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {} 1143 1144 void work(uint worker_id) { 1145 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1146 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer); 1147 } 1148 }; 1149 1150 class PostCompactionPrinterClosure: public HeapRegionClosure { 1151 private: 1152 G1HRPrinter* _hr_printer; 1153 public: 1154 bool doHeapRegion(HeapRegion* hr) { 1155 assert(!hr->is_young(), "not expecting to find young regions"); 1156 if (hr->is_free()) { 1157 // We only generate output for non-empty regions. 1158 } else if (hr->is_starts_humongous()) { 1159 if (hr->region_num() == 1) { 1160 // single humongous region 1161 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1162 } else { 1163 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1164 } 1165 } else if (hr->is_continues_humongous()) { 1166 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1167 } else if (hr->is_old()) { 1168 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1169 } else { 1170 ShouldNotReachHere(); 1171 } 1172 return false; 1173 } 1174 1175 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1176 : _hr_printer(hr_printer) { } 1177 }; 1178 1179 void G1CollectedHeap::print_hrm_post_compaction() { 1180 PostCompactionPrinterClosure cl(hr_printer()); 1181 heap_region_iterate(&cl); 1182 } 1183 1184 bool G1CollectedHeap::do_collection(bool explicit_gc, 1185 bool clear_all_soft_refs, 1186 size_t word_size) { 1187 assert_at_safepoint(true /* should_be_vm_thread */); 1188 1189 if (GC_locker::check_active_before_gc()) { 1190 return false; 1191 } 1192 1193 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1194 gc_timer->register_gc_start(); 1195 1196 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1197 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1198 1199 SvcGCMarker sgcm(SvcGCMarker::FULL); 1200 ResourceMark rm; 1201 1202 print_heap_before_gc(); 1203 trace_heap_before_gc(gc_tracer); 1204 1205 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1206 1207 verify_region_sets_optional(); 1208 1209 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1210 collector_policy()->should_clear_all_soft_refs(); 1211 1212 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1213 1214 { 1215 IsGCActiveMark x; 1216 1217 // Timing 1218 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); 1219 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1220 1221 { 1222 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id()); 1223 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1224 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1225 1226 g1_policy()->record_full_collection_start(); 1227 1228 // Note: When we have a more flexible GC logging framework that 1229 // allows us to add optional attributes to a GC log record we 1230 // could consider timing and reporting how long we wait in the 1231 // following two methods. 1232 wait_while_free_regions_coming(); 1233 // If we start the compaction before the CM threads finish 1234 // scanning the root regions we might trip them over as we'll 1235 // be moving objects / updating references. So let's wait until 1236 // they are done. By telling them to abort, they should complete 1237 // early. 1238 _cm->root_regions()->abort(); 1239 _cm->root_regions()->wait_until_scan_finished(); 1240 append_secondary_free_list_if_not_empty_with_lock(); 1241 1242 gc_prologue(true); 1243 increment_total_collections(true /* full gc */); 1244 increment_old_marking_cycles_started(); 1245 1246 assert(used() == recalculate_used(), "Should be equal"); 1247 1248 verify_before_gc(); 1249 1250 check_bitmaps("Full GC Start"); 1251 pre_full_gc_dump(gc_timer); 1252 1253 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1254 1255 // Disable discovery and empty the discovered lists 1256 // for the CM ref processor. 1257 ref_processor_cm()->disable_discovery(); 1258 ref_processor_cm()->abandon_partial_discovery(); 1259 ref_processor_cm()->verify_no_references_recorded(); 1260 1261 // Abandon current iterations of concurrent marking and concurrent 1262 // refinement, if any are in progress. We have to do this before 1263 // wait_until_scan_finished() below. 1264 concurrent_mark()->abort(); 1265 1266 // Make sure we'll choose a new allocation region afterwards. 1267 _allocator->release_mutator_alloc_region(); 1268 _allocator->abandon_gc_alloc_regions(); 1269 g1_rem_set()->cleanupHRRS(); 1270 1271 // We should call this after we retire any currently active alloc 1272 // regions so that all the ALLOC / RETIRE events are generated 1273 // before the start GC event. 1274 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1275 1276 // We may have added regions to the current incremental collection 1277 // set between the last GC or pause and now. We need to clear the 1278 // incremental collection set and then start rebuilding it afresh 1279 // after this full GC. 1280 abandon_collection_set(g1_policy()->inc_cset_head()); 1281 g1_policy()->clear_incremental_cset(); 1282 g1_policy()->stop_incremental_cset_building(); 1283 1284 tear_down_region_sets(false /* free_list_only */); 1285 g1_policy()->set_gcs_are_young(true); 1286 1287 // See the comments in g1CollectedHeap.hpp and 1288 // G1CollectedHeap::ref_processing_init() about 1289 // how reference processing currently works in G1. 1290 1291 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1292 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1293 1294 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1295 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1296 1297 ref_processor_stw()->enable_discovery(); 1298 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1299 1300 // Do collection work 1301 { 1302 HandleMark hm; // Discard invalid handles created during gc 1303 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1304 } 1305 1306 assert(num_free_regions() == 0, "we should not have added any free regions"); 1307 rebuild_region_sets(false /* free_list_only */); 1308 1309 // Enqueue any discovered reference objects that have 1310 // not been removed from the discovered lists. 1311 ref_processor_stw()->enqueue_discovered_references(); 1312 1313 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1314 1315 MemoryService::track_memory_usage(); 1316 1317 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1318 ref_processor_stw()->verify_no_references_recorded(); 1319 1320 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1321 ClassLoaderDataGraph::purge(); 1322 MetaspaceAux::verify_metrics(); 1323 1324 // Note: since we've just done a full GC, concurrent 1325 // marking is no longer active. Therefore we need not 1326 // re-enable reference discovery for the CM ref processor. 1327 // That will be done at the start of the next marking cycle. 1328 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1329 ref_processor_cm()->verify_no_references_recorded(); 1330 1331 reset_gc_time_stamp(); 1332 // Since everything potentially moved, we will clear all remembered 1333 // sets, and clear all cards. Later we will rebuild remembered 1334 // sets. We will also reset the GC time stamps of the regions. 1335 clear_rsets_post_compaction(); 1336 check_gc_time_stamps(); 1337 1338 // Resize the heap if necessary. 1339 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1340 1341 if (_hr_printer.is_active()) { 1342 // We should do this after we potentially resize the heap so 1343 // that all the COMMIT / UNCOMMIT events are generated before 1344 // the end GC event. 1345 1346 print_hrm_post_compaction(); 1347 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1348 } 1349 1350 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1351 if (hot_card_cache->use_cache()) { 1352 hot_card_cache->reset_card_counts(); 1353 hot_card_cache->reset_hot_cache(); 1354 } 1355 1356 // Rebuild remembered sets of all regions. 1357 uint n_workers = 1358 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1359 workers()->active_workers(), 1360 Threads::number_of_non_daemon_threads()); 1361 assert(UseDynamicNumberOfGCThreads || 1362 n_workers == workers()->total_workers(), 1363 "If not dynamic should be using all the workers"); 1364 workers()->set_active_workers(n_workers); 1365 // Set parallel threads in the heap (_n_par_threads) only 1366 // before a parallel phase and always reset it to 0 after 1367 // the phase so that the number of parallel threads does 1368 // no get carried forward to a serial phase where there 1369 // may be code that is "possibly_parallel". 1370 set_par_threads(n_workers); 1371 1372 ParRebuildRSTask rebuild_rs_task(this); 1373 assert(UseDynamicNumberOfGCThreads || 1374 workers()->active_workers() == workers()->total_workers(), 1375 "Unless dynamic should use total workers"); 1376 // Use the most recent number of active workers 1377 assert(workers()->active_workers() > 0, 1378 "Active workers not properly set"); 1379 set_par_threads(workers()->active_workers()); 1380 workers()->run_task(&rebuild_rs_task); 1381 set_par_threads(0); 1382 1383 // Rebuild the strong code root lists for each region 1384 rebuild_strong_code_roots(); 1385 1386 if (true) { // FIXME 1387 MetaspaceGC::compute_new_size(); 1388 } 1389 1390 #ifdef TRACESPINNING 1391 ParallelTaskTerminator::print_termination_counts(); 1392 #endif 1393 1394 // Discard all rset updates 1395 JavaThread::dirty_card_queue_set().abandon_logs(); 1396 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1397 1398 _young_list->reset_sampled_info(); 1399 // At this point there should be no regions in the 1400 // entire heap tagged as young. 1401 assert(check_young_list_empty(true /* check_heap */), 1402 "young list should be empty at this point"); 1403 1404 // Update the number of full collections that have been completed. 1405 increment_old_marking_cycles_completed(false /* concurrent */); 1406 1407 _hrm.verify_optional(); 1408 verify_region_sets_optional(); 1409 1410 verify_after_gc(); 1411 1412 // Clear the previous marking bitmap, if needed for bitmap verification. 1413 // Note we cannot do this when we clear the next marking bitmap in 1414 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1415 // objects marked during a full GC against the previous bitmap. 1416 // But we need to clear it before calling check_bitmaps below since 1417 // the full GC has compacted objects and updated TAMS but not updated 1418 // the prev bitmap. 1419 if (G1VerifyBitmaps) { 1420 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1421 } 1422 check_bitmaps("Full GC End"); 1423 1424 // Start a new incremental collection set for the next pause 1425 assert(g1_policy()->collection_set() == NULL, "must be"); 1426 g1_policy()->start_incremental_cset_building(); 1427 1428 clear_cset_fast_test(); 1429 1430 _allocator->init_mutator_alloc_region(); 1431 1432 g1_policy()->record_full_collection_end(); 1433 1434 if (G1Log::fine()) { 1435 g1_policy()->print_heap_transition(); 1436 } 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 if (G1Log::finer()) { 1448 g1_policy()->print_detailed_heap_transition(true /* full */); 1449 } 1450 1451 print_heap_after_gc(); 1452 trace_heap_after_gc(gc_tracer); 1453 1454 post_full_gc_dump(gc_timer); 1455 1456 gc_timer->register_gc_end(); 1457 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1458 } 1459 1460 return true; 1461 } 1462 1463 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1464 // do_collection() will return whether it succeeded in performing 1465 // the GC. Currently, there is no facility on the 1466 // do_full_collection() API to notify the caller than the collection 1467 // did not succeed (e.g., because it was locked out by the GC 1468 // locker). So, right now, we'll ignore the return value. 1469 bool dummy = do_collection(true, /* explicit_gc */ 1470 clear_all_soft_refs, 1471 0 /* word_size */); 1472 } 1473 1474 // This code is mostly copied from TenuredGeneration. 1475 void 1476 G1CollectedHeap:: 1477 resize_if_necessary_after_full_collection(size_t word_size) { 1478 // Include the current allocation, if any, and bytes that will be 1479 // pre-allocated to support collections, as "used". 1480 const size_t used_after_gc = used(); 1481 const size_t capacity_after_gc = capacity(); 1482 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1483 1484 // This is enforced in arguments.cpp. 1485 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1486 "otherwise the code below doesn't make sense"); 1487 1488 // We don't have floating point command-line arguments 1489 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1490 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1491 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1492 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1493 1494 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1495 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1496 1497 // We have to be careful here as these two calculations can overflow 1498 // 32-bit size_t's. 1499 double used_after_gc_d = (double) used_after_gc; 1500 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1501 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1502 1503 // Let's make sure that they are both under the max heap size, which 1504 // by default will make them fit into a size_t. 1505 double desired_capacity_upper_bound = (double) max_heap_size; 1506 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1507 desired_capacity_upper_bound); 1508 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1509 desired_capacity_upper_bound); 1510 1511 // We can now safely turn them into size_t's. 1512 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1513 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1514 1515 // This assert only makes sense here, before we adjust them 1516 // with respect to the min and max heap size. 1517 assert(minimum_desired_capacity <= maximum_desired_capacity, 1518 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1519 "maximum_desired_capacity = "SIZE_FORMAT, 1520 minimum_desired_capacity, maximum_desired_capacity)); 1521 1522 // Should not be greater than the heap max size. No need to adjust 1523 // it with respect to the heap min size as it's a lower bound (i.e., 1524 // we'll try to make the capacity larger than it, not smaller). 1525 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1526 // Should not be less than the heap min size. No need to adjust it 1527 // with respect to the heap max size as it's an upper bound (i.e., 1528 // we'll try to make the capacity smaller than it, not greater). 1529 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1530 1531 if (capacity_after_gc < minimum_desired_capacity) { 1532 // Don't expand unless it's significant 1533 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1534 ergo_verbose4(ErgoHeapSizing, 1535 "attempt heap expansion", 1536 ergo_format_reason("capacity lower than " 1537 "min desired capacity after Full GC") 1538 ergo_format_byte("capacity") 1539 ergo_format_byte("occupancy") 1540 ergo_format_byte_perc("min desired capacity"), 1541 capacity_after_gc, used_after_gc, 1542 minimum_desired_capacity, (double) MinHeapFreeRatio); 1543 expand(expand_bytes); 1544 1545 // No expansion, now see if we want to shrink 1546 } else if (capacity_after_gc > maximum_desired_capacity) { 1547 // Capacity too large, compute shrinking size 1548 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1549 ergo_verbose4(ErgoHeapSizing, 1550 "attempt heap shrinking", 1551 ergo_format_reason("capacity higher than " 1552 "max desired capacity after Full GC") 1553 ergo_format_byte("capacity") 1554 ergo_format_byte("occupancy") 1555 ergo_format_byte_perc("max desired capacity"), 1556 capacity_after_gc, used_after_gc, 1557 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1558 shrink(shrink_bytes); 1559 } 1560 } 1561 1562 1563 HeapWord* 1564 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1565 AllocationContext_t context, 1566 bool* succeeded) { 1567 assert_at_safepoint(true /* should_be_vm_thread */); 1568 1569 *succeeded = true; 1570 // Let's attempt the allocation first. 1571 HeapWord* result = 1572 attempt_allocation_at_safepoint(word_size, 1573 context, 1574 false /* expect_null_mutator_alloc_region */); 1575 if (result != NULL) { 1576 assert(*succeeded, "sanity"); 1577 return result; 1578 } 1579 1580 // In a G1 heap, we're supposed to keep allocation from failing by 1581 // incremental pauses. Therefore, at least for now, we'll favor 1582 // expansion over collection. (This might change in the future if we can 1583 // do something smarter than full collection to satisfy a failed alloc.) 1584 result = expand_and_allocate(word_size, context); 1585 if (result != NULL) { 1586 assert(*succeeded, "sanity"); 1587 return result; 1588 } 1589 1590 // Expansion didn't work, we'll try to do a Full GC. 1591 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1592 false, /* clear_all_soft_refs */ 1593 word_size); 1594 if (!gc_succeeded) { 1595 *succeeded = false; 1596 return NULL; 1597 } 1598 1599 // Retry the allocation 1600 result = attempt_allocation_at_safepoint(word_size, 1601 context, 1602 true /* expect_null_mutator_alloc_region */); 1603 if (result != NULL) { 1604 assert(*succeeded, "sanity"); 1605 return result; 1606 } 1607 1608 // Then, try a Full GC that will collect all soft references. 1609 gc_succeeded = do_collection(false, /* explicit_gc */ 1610 true, /* clear_all_soft_refs */ 1611 word_size); 1612 if (!gc_succeeded) { 1613 *succeeded = false; 1614 return NULL; 1615 } 1616 1617 // Retry the allocation once more 1618 result = attempt_allocation_at_safepoint(word_size, 1619 context, 1620 true /* expect_null_mutator_alloc_region */); 1621 if (result != NULL) { 1622 assert(*succeeded, "sanity"); 1623 return result; 1624 } 1625 1626 assert(!collector_policy()->should_clear_all_soft_refs(), 1627 "Flag should have been handled and cleared prior to this point"); 1628 1629 // What else? We might try synchronous finalization later. If the total 1630 // space available is large enough for the allocation, then a more 1631 // complete compaction phase than we've tried so far might be 1632 // appropriate. 1633 assert(*succeeded, "sanity"); 1634 return NULL; 1635 } 1636 1637 // Attempting to expand the heap sufficiently 1638 // to support an allocation of the given "word_size". If 1639 // successful, perform the allocation and return the address of the 1640 // allocated block, or else "NULL". 1641 1642 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1643 assert_at_safepoint(true /* should_be_vm_thread */); 1644 1645 verify_region_sets_optional(); 1646 1647 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1648 ergo_verbose1(ErgoHeapSizing, 1649 "attempt heap expansion", 1650 ergo_format_reason("allocation request failed") 1651 ergo_format_byte("allocation request"), 1652 word_size * HeapWordSize); 1653 if (expand(expand_bytes)) { 1654 _hrm.verify_optional(); 1655 verify_region_sets_optional(); 1656 return attempt_allocation_at_safepoint(word_size, 1657 context, 1658 false /* expect_null_mutator_alloc_region */); 1659 } 1660 return NULL; 1661 } 1662 1663 bool G1CollectedHeap::expand(size_t expand_bytes) { 1664 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1665 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1666 HeapRegion::GrainBytes); 1667 ergo_verbose2(ErgoHeapSizing, 1668 "expand the heap", 1669 ergo_format_byte("requested expansion amount") 1670 ergo_format_byte("attempted expansion amount"), 1671 expand_bytes, aligned_expand_bytes); 1672 1673 if (is_maximal_no_gc()) { 1674 ergo_verbose0(ErgoHeapSizing, 1675 "did not expand the heap", 1676 ergo_format_reason("heap already fully expanded")); 1677 return false; 1678 } 1679 1680 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1681 assert(regions_to_expand > 0, "Must expand by at least one region"); 1682 1683 uint expanded_by = _hrm.expand_by(regions_to_expand); 1684 1685 if (expanded_by > 0) { 1686 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1687 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1688 g1_policy()->record_new_heap_size(num_regions()); 1689 } else { 1690 ergo_verbose0(ErgoHeapSizing, 1691 "did not expand the heap", 1692 ergo_format_reason("heap expansion operation failed")); 1693 // The expansion of the virtual storage space was unsuccessful. 1694 // Let's see if it was because we ran out of swap. 1695 if (G1ExitOnExpansionFailure && 1696 _hrm.available() >= regions_to_expand) { 1697 // We had head room... 1698 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1699 } 1700 } 1701 return regions_to_expand > 0; 1702 } 1703 1704 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1705 size_t aligned_shrink_bytes = 1706 ReservedSpace::page_align_size_down(shrink_bytes); 1707 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1708 HeapRegion::GrainBytes); 1709 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1710 1711 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1712 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1713 1714 ergo_verbose3(ErgoHeapSizing, 1715 "shrink the heap", 1716 ergo_format_byte("requested shrinking amount") 1717 ergo_format_byte("aligned shrinking amount") 1718 ergo_format_byte("attempted shrinking amount"), 1719 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1720 if (num_regions_removed > 0) { 1721 g1_policy()->record_new_heap_size(num_regions()); 1722 } else { 1723 ergo_verbose0(ErgoHeapSizing, 1724 "did not shrink the heap", 1725 ergo_format_reason("heap shrinking operation failed")); 1726 } 1727 } 1728 1729 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1730 verify_region_sets_optional(); 1731 1732 // We should only reach here at the end of a Full GC which means we 1733 // should not not be holding to any GC alloc regions. The method 1734 // below will make sure of that and do any remaining clean up. 1735 _allocator->abandon_gc_alloc_regions(); 1736 1737 // Instead of tearing down / rebuilding the free lists here, we 1738 // could instead use the remove_all_pending() method on free_list to 1739 // remove only the ones that we need to remove. 1740 tear_down_region_sets(true /* free_list_only */); 1741 shrink_helper(shrink_bytes); 1742 rebuild_region_sets(true /* free_list_only */); 1743 1744 _hrm.verify_optional(); 1745 verify_region_sets_optional(); 1746 } 1747 1748 // Public methods. 1749 1750 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1751 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1752 #endif // _MSC_VER 1753 1754 1755 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1756 SharedHeap(policy_), 1757 _g1_policy(policy_), 1758 _dirty_card_queue_set(false), 1759 _into_cset_dirty_card_queue_set(false), 1760 _is_alive_closure_cm(this), 1761 _is_alive_closure_stw(this), 1762 _ref_processor_cm(NULL), 1763 _ref_processor_stw(NULL), 1764 _bot_shared(NULL), 1765 _evac_failure_scan_stack(NULL), 1766 _mark_in_progress(false), 1767 _cg1r(NULL), 1768 _g1mm(NULL), 1769 _refine_cte_cl(NULL), 1770 _full_collection(false), 1771 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1772 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1773 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1774 _humongous_is_live(), 1775 _has_humongous_reclaim_candidates(false), 1776 _free_regions_coming(false), 1777 _young_list(new YoungList(this)), 1778 _gc_time_stamp(0), 1779 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1780 _old_plab_stats(OldPLABSize, PLABWeight), 1781 _expand_heap_after_alloc_failure(true), 1782 _surviving_young_words(NULL), 1783 _old_marking_cycles_started(0), 1784 _old_marking_cycles_completed(0), 1785 _concurrent_cycle_started(false), 1786 _heap_summary_sent(false), 1787 _in_cset_fast_test(), 1788 _dirty_cards_region_list(NULL), 1789 _worker_cset_start_region(NULL), 1790 _worker_cset_start_region_time_stamp(NULL), 1791 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1792 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1793 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1794 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1795 1796 _g1h = this; 1797 1798 _allocator = G1Allocator::create_allocator(_g1h); 1799 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1800 1801 int n_queues = MAX2((int)ParallelGCThreads, 1); 1802 _task_queues = new RefToScanQueueSet(n_queues); 1803 1804 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1805 assert(n_rem_sets > 0, "Invariant."); 1806 1807 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1808 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC); 1809 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1810 1811 for (int i = 0; i < n_queues; i++) { 1812 RefToScanQueue* q = new RefToScanQueue(); 1813 q->initialize(); 1814 _task_queues->register_queue(i, q); 1815 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1816 } 1817 clear_cset_start_regions(); 1818 1819 // Initialize the G1EvacuationFailureALot counters and flags. 1820 NOT_PRODUCT(reset_evacuation_should_fail();) 1821 1822 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1823 } 1824 1825 jint G1CollectedHeap::initialize() { 1826 CollectedHeap::pre_initialize(); 1827 os::enable_vtime(); 1828 1829 G1Log::init(); 1830 1831 // Necessary to satisfy locking discipline assertions. 1832 1833 MutexLocker x(Heap_lock); 1834 1835 // We have to initialize the printer before committing the heap, as 1836 // it will be used then. 1837 _hr_printer.set_active(G1PrintHeapRegions); 1838 1839 // While there are no constraints in the GC code that HeapWordSize 1840 // be any particular value, there are multiple other areas in the 1841 // system which believe this to be true (e.g. oop->object_size in some 1842 // cases incorrectly returns the size in wordSize units rather than 1843 // HeapWordSize). 1844 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1845 1846 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1847 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1848 size_t heap_alignment = collector_policy()->heap_alignment(); 1849 1850 // Ensure that the sizes are properly aligned. 1851 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1852 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1853 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1854 1855 _refine_cte_cl = new RefineCardTableEntryClosure(); 1856 1857 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl); 1858 1859 // Reserve the maximum. 1860 1861 // When compressed oops are enabled, the preferred heap base 1862 // is calculated by subtracting the requested size from the 1863 // 32Gb boundary and using the result as the base address for 1864 // heap reservation. If the requested size is not aligned to 1865 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1866 // into the ReservedHeapSpace constructor) then the actual 1867 // base of the reserved heap may end up differing from the 1868 // address that was requested (i.e. the preferred heap base). 1869 // If this happens then we could end up using a non-optimal 1870 // compressed oops mode. 1871 1872 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1873 heap_alignment); 1874 1875 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1876 1877 // Create the barrier set for the entire reserved region. 1878 G1SATBCardTableLoggingModRefBS* bs 1879 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 1880 bs->initialize(); 1881 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 1882 set_barrier_set(bs); 1883 1884 // Also create a G1 rem set. 1885 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 1886 1887 // Carve out the G1 part of the heap. 1888 1889 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1890 G1RegionToSpaceMapper* heap_storage = 1891 G1RegionToSpaceMapper::create_mapper(g1_rs, 1892 UseLargePages ? os::large_page_size() : os::vm_page_size(), 1893 HeapRegion::GrainBytes, 1894 1, 1895 mtJavaHeap); 1896 heap_storage->set_mapping_changed_listener(&_listener); 1897 1898 // Reserve space for the block offset table. We do not support automatic uncommit 1899 // for the card table at this time. BOT only. 1900 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize)); 1901 G1RegionToSpaceMapper* bot_storage = 1902 G1RegionToSpaceMapper::create_mapper(bot_rs, 1903 os::vm_page_size(), 1904 HeapRegion::GrainBytes, 1905 G1BlockOffsetSharedArray::N_bytes, 1906 mtGC); 1907 1908 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 1909 G1RegionToSpaceMapper* cardtable_storage = 1910 G1RegionToSpaceMapper::create_mapper(cardtable_rs, 1911 os::vm_page_size(), 1912 HeapRegion::GrainBytes, 1913 G1BlockOffsetSharedArray::N_bytes, 1914 mtGC); 1915 1916 // Reserve space for the card counts table. 1917 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize)); 1918 G1RegionToSpaceMapper* card_counts_storage = 1919 G1RegionToSpaceMapper::create_mapper(card_counts_rs, 1920 os::vm_page_size(), 1921 HeapRegion::GrainBytes, 1922 G1BlockOffsetSharedArray::N_bytes, 1923 mtGC); 1924 1925 // Reserve space for prev and next bitmap. 1926 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); 1927 1928 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size)); 1929 G1RegionToSpaceMapper* prev_bitmap_storage = 1930 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs, 1931 os::vm_page_size(), 1932 HeapRegion::GrainBytes, 1933 CMBitMap::mark_distance(), 1934 mtGC); 1935 1936 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size)); 1937 G1RegionToSpaceMapper* next_bitmap_storage = 1938 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs, 1939 os::vm_page_size(), 1940 HeapRegion::GrainBytes, 1941 CMBitMap::mark_distance(), 1942 mtGC); 1943 1944 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1945 g1_barrier_set()->initialize(cardtable_storage); 1946 // Do later initialization work for concurrent refinement. 1947 _cg1r->init(card_counts_storage); 1948 1949 // 6843694 - ensure that the maximum region index can fit 1950 // in the remembered set structures. 1951 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1952 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1953 1954 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1955 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1956 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1957 "too many cards per region"); 1958 1959 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1960 1961 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage); 1962 1963 _g1h = this; 1964 1965 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes); 1966 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes); 1967 1968 // Create the ConcurrentMark data structure and thread. 1969 // (Must do this late, so that "max_regions" is defined.) 1970 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1971 if (_cm == NULL || !_cm->completed_initialization()) { 1972 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 1973 return JNI_ENOMEM; 1974 } 1975 _cmThread = _cm->cmThread(); 1976 1977 // Initialize the from_card cache structure of HeapRegionRemSet. 1978 HeapRegionRemSet::init_heap(max_regions()); 1979 1980 // Now expand into the initial heap size. 1981 if (!expand(init_byte_size)) { 1982 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1983 return JNI_ENOMEM; 1984 } 1985 1986 // Perform any initialization actions delegated to the policy. 1987 g1_policy()->init(); 1988 1989 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 1990 SATB_Q_FL_lock, 1991 G1SATBProcessCompletedThreshold, 1992 Shared_SATB_Q_lock); 1993 1994 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 1995 DirtyCardQ_CBL_mon, 1996 DirtyCardQ_FL_lock, 1997 concurrent_g1_refine()->yellow_zone(), 1998 concurrent_g1_refine()->red_zone(), 1999 Shared_DirtyCardQ_lock); 2000 2001 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 2002 DirtyCardQ_CBL_mon, 2003 DirtyCardQ_FL_lock, 2004 -1, // never trigger processing 2005 -1, // no limit on length 2006 Shared_DirtyCardQ_lock, 2007 &JavaThread::dirty_card_queue_set()); 2008 2009 // Initialize the card queue set used to hold cards containing 2010 // references into the collection set. 2011 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 2012 DirtyCardQ_CBL_mon, 2013 DirtyCardQ_FL_lock, 2014 -1, // never trigger processing 2015 -1, // no limit on length 2016 Shared_DirtyCardQ_lock, 2017 &JavaThread::dirty_card_queue_set()); 2018 2019 // Here we allocate the dummy HeapRegion that is required by the 2020 // G1AllocRegion class. 2021 HeapRegion* dummy_region = _hrm.get_dummy_region(); 2022 2023 // We'll re-use the same region whether the alloc region will 2024 // require BOT updates or not and, if it doesn't, then a non-young 2025 // region will complain that it cannot support allocations without 2026 // BOT updates. So we'll tag the dummy region as eden to avoid that. 2027 dummy_region->set_eden(); 2028 // Make sure it's full. 2029 dummy_region->set_top(dummy_region->end()); 2030 G1AllocRegion::setup(this, dummy_region); 2031 2032 _allocator->init_mutator_alloc_region(); 2033 2034 // Do create of the monitoring and management support so that 2035 // values in the heap have been properly initialized. 2036 _g1mm = new G1MonitoringSupport(this); 2037 2038 G1StringDedup::initialize(); 2039 2040 return JNI_OK; 2041 } 2042 2043 void G1CollectedHeap::stop() { 2044 // Stop all concurrent threads. We do this to make sure these threads 2045 // do not continue to execute and access resources (e.g. gclog_or_tty) 2046 // that are destroyed during shutdown. 2047 _cg1r->stop(); 2048 _cmThread->stop(); 2049 if (G1StringDedup::is_enabled()) { 2050 G1StringDedup::stop(); 2051 } 2052 } 2053 2054 void G1CollectedHeap::clear_humongous_is_live_table() { 2055 guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true"); 2056 _humongous_is_live.clear(); 2057 } 2058 2059 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2060 return HeapRegion::max_region_size(); 2061 } 2062 2063 void G1CollectedHeap::ref_processing_init() { 2064 // Reference processing in G1 currently works as follows: 2065 // 2066 // * There are two reference processor instances. One is 2067 // used to record and process discovered references 2068 // during concurrent marking; the other is used to 2069 // record and process references during STW pauses 2070 // (both full and incremental). 2071 // * Both ref processors need to 'span' the entire heap as 2072 // the regions in the collection set may be dotted around. 2073 // 2074 // * For the concurrent marking ref processor: 2075 // * Reference discovery is enabled at initial marking. 2076 // * Reference discovery is disabled and the discovered 2077 // references processed etc during remarking. 2078 // * Reference discovery is MT (see below). 2079 // * Reference discovery requires a barrier (see below). 2080 // * Reference processing may or may not be MT 2081 // (depending on the value of ParallelRefProcEnabled 2082 // and ParallelGCThreads). 2083 // * A full GC disables reference discovery by the CM 2084 // ref processor and abandons any entries on it's 2085 // discovered lists. 2086 // 2087 // * For the STW processor: 2088 // * Non MT discovery is enabled at the start of a full GC. 2089 // * Processing and enqueueing during a full GC is non-MT. 2090 // * During a full GC, references are processed after marking. 2091 // 2092 // * Discovery (may or may not be MT) is enabled at the start 2093 // of an incremental evacuation pause. 2094 // * References are processed near the end of a STW evacuation pause. 2095 // * For both types of GC: 2096 // * Discovery is atomic - i.e. not concurrent. 2097 // * Reference discovery will not need a barrier. 2098 2099 SharedHeap::ref_processing_init(); 2100 MemRegion mr = reserved_region(); 2101 2102 // Concurrent Mark ref processor 2103 _ref_processor_cm = 2104 new ReferenceProcessor(mr, // span 2105 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2106 // mt processing 2107 (int) ParallelGCThreads, 2108 // degree of mt processing 2109 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2110 // mt discovery 2111 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2112 // degree of mt discovery 2113 false, 2114 // Reference discovery is not atomic 2115 &_is_alive_closure_cm); 2116 // is alive closure 2117 // (for efficiency/performance) 2118 2119 // STW ref processor 2120 _ref_processor_stw = 2121 new ReferenceProcessor(mr, // span 2122 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2123 // mt processing 2124 MAX2((int)ParallelGCThreads, 1), 2125 // degree of mt processing 2126 (ParallelGCThreads > 1), 2127 // mt discovery 2128 MAX2((int)ParallelGCThreads, 1), 2129 // degree of mt discovery 2130 true, 2131 // Reference discovery is atomic 2132 &_is_alive_closure_stw); 2133 // is alive closure 2134 // (for efficiency/performance) 2135 } 2136 2137 size_t G1CollectedHeap::capacity() const { 2138 return _hrm.length() * HeapRegion::GrainBytes; 2139 } 2140 2141 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2142 assert(!hr->is_continues_humongous(), "pre-condition"); 2143 hr->reset_gc_time_stamp(); 2144 if (hr->is_starts_humongous()) { 2145 uint first_index = hr->hrm_index() + 1; 2146 uint last_index = hr->last_hc_index(); 2147 for (uint i = first_index; i < last_index; i += 1) { 2148 HeapRegion* chr = region_at(i); 2149 assert(chr->is_continues_humongous(), "sanity"); 2150 chr->reset_gc_time_stamp(); 2151 } 2152 } 2153 } 2154 2155 #ifndef PRODUCT 2156 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2157 private: 2158 unsigned _gc_time_stamp; 2159 bool _failures; 2160 2161 public: 2162 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2163 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2164 2165 virtual bool doHeapRegion(HeapRegion* hr) { 2166 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2167 if (_gc_time_stamp != region_gc_time_stamp) { 2168 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2169 "expected %d", HR_FORMAT_PARAMS(hr), 2170 region_gc_time_stamp, _gc_time_stamp); 2171 _failures = true; 2172 } 2173 return false; 2174 } 2175 2176 bool failures() { return _failures; } 2177 }; 2178 2179 void G1CollectedHeap::check_gc_time_stamps() { 2180 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2181 heap_region_iterate(&cl); 2182 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2183 } 2184 #endif // PRODUCT 2185 2186 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2187 DirtyCardQueue* into_cset_dcq, 2188 bool concurrent, 2189 uint worker_i) { 2190 // Clean cards in the hot card cache 2191 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2192 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2193 2194 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2195 size_t n_completed_buffers = 0; 2196 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2197 n_completed_buffers++; 2198 } 2199 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 2200 dcqs.clear_n_completed_buffers(); 2201 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2202 } 2203 2204 2205 // Computes the sum of the storage used by the various regions. 2206 size_t G1CollectedHeap::used() const { 2207 return _allocator->used(); 2208 } 2209 2210 size_t G1CollectedHeap::used_unlocked() const { 2211 return _allocator->used_unlocked(); 2212 } 2213 2214 class SumUsedClosure: public HeapRegionClosure { 2215 size_t _used; 2216 public: 2217 SumUsedClosure() : _used(0) {} 2218 bool doHeapRegion(HeapRegion* r) { 2219 if (!r->is_continues_humongous()) { 2220 _used += r->used(); 2221 } 2222 return false; 2223 } 2224 size_t result() { return _used; } 2225 }; 2226 2227 size_t G1CollectedHeap::recalculate_used() const { 2228 double recalculate_used_start = os::elapsedTime(); 2229 2230 SumUsedClosure blk; 2231 heap_region_iterate(&blk); 2232 2233 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2234 return blk.result(); 2235 } 2236 2237 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2238 switch (cause) { 2239 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2240 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2241 case GCCause::_g1_humongous_allocation: return true; 2242 case GCCause::_update_allocation_context_stats_inc: return true; 2243 case GCCause::_wb_conc_mark: return true; 2244 default: return false; 2245 } 2246 } 2247 2248 #ifndef PRODUCT 2249 void G1CollectedHeap::allocate_dummy_regions() { 2250 // Let's fill up most of the region 2251 size_t word_size = HeapRegion::GrainWords - 1024; 2252 // And as a result the region we'll allocate will be humongous. 2253 guarantee(is_humongous(word_size), "sanity"); 2254 2255 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2256 // Let's use the existing mechanism for the allocation 2257 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2258 AllocationContext::system()); 2259 if (dummy_obj != NULL) { 2260 MemRegion mr(dummy_obj, word_size); 2261 CollectedHeap::fill_with_object(mr); 2262 } else { 2263 // If we can't allocate once, we probably cannot allocate 2264 // again. Let's get out of the loop. 2265 break; 2266 } 2267 } 2268 } 2269 #endif // !PRODUCT 2270 2271 void G1CollectedHeap::increment_old_marking_cycles_started() { 2272 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2273 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2274 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2275 _old_marking_cycles_started, _old_marking_cycles_completed)); 2276 2277 _old_marking_cycles_started++; 2278 } 2279 2280 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2281 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2282 2283 // We assume that if concurrent == true, then the caller is a 2284 // concurrent thread that was joined the Suspendible Thread 2285 // Set. If there's ever a cheap way to check this, we should add an 2286 // assert here. 2287 2288 // Given that this method is called at the end of a Full GC or of a 2289 // concurrent cycle, and those can be nested (i.e., a Full GC can 2290 // interrupt a concurrent cycle), the number of full collections 2291 // completed should be either one (in the case where there was no 2292 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2293 // behind the number of full collections started. 2294 2295 // This is the case for the inner caller, i.e. a Full GC. 2296 assert(concurrent || 2297 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2298 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2299 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2300 "is inconsistent with _old_marking_cycles_completed = %u", 2301 _old_marking_cycles_started, _old_marking_cycles_completed)); 2302 2303 // This is the case for the outer caller, i.e. the concurrent cycle. 2304 assert(!concurrent || 2305 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2306 err_msg("for outer caller (concurrent cycle): " 2307 "_old_marking_cycles_started = %u " 2308 "is inconsistent with _old_marking_cycles_completed = %u", 2309 _old_marking_cycles_started, _old_marking_cycles_completed)); 2310 2311 _old_marking_cycles_completed += 1; 2312 2313 // We need to clear the "in_progress" flag in the CM thread before 2314 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2315 // is set) so that if a waiter requests another System.gc() it doesn't 2316 // incorrectly see that a marking cycle is still in progress. 2317 if (concurrent) { 2318 _cmThread->clear_in_progress(); 2319 } 2320 2321 // This notify_all() will ensure that a thread that called 2322 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2323 // and it's waiting for a full GC to finish will be woken up. It is 2324 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2325 FullGCCount_lock->notify_all(); 2326 } 2327 2328 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2329 _concurrent_cycle_started = true; 2330 _gc_timer_cm->register_gc_start(start_time); 2331 2332 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2333 trace_heap_before_gc(_gc_tracer_cm); 2334 } 2335 2336 void G1CollectedHeap::register_concurrent_cycle_end() { 2337 if (_concurrent_cycle_started) { 2338 if (_cm->has_aborted()) { 2339 _gc_tracer_cm->report_concurrent_mode_failure(); 2340 } 2341 2342 _gc_timer_cm->register_gc_end(); 2343 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2344 2345 // Clear state variables to prepare for the next concurrent cycle. 2346 _concurrent_cycle_started = false; 2347 _heap_summary_sent = false; 2348 } 2349 } 2350 2351 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2352 if (_concurrent_cycle_started) { 2353 // This function can be called when: 2354 // the cleanup pause is run 2355 // the concurrent cycle is aborted before the cleanup pause. 2356 // the concurrent cycle is aborted after the cleanup pause, 2357 // but before the concurrent cycle end has been registered. 2358 // Make sure that we only send the heap information once. 2359 if (!_heap_summary_sent) { 2360 trace_heap_after_gc(_gc_tracer_cm); 2361 _heap_summary_sent = true; 2362 } 2363 } 2364 } 2365 2366 G1YCType G1CollectedHeap::yc_type() { 2367 bool is_young = g1_policy()->gcs_are_young(); 2368 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2369 bool is_during_mark = mark_in_progress(); 2370 2371 if (is_initial_mark) { 2372 return InitialMark; 2373 } else if (is_during_mark) { 2374 return DuringMark; 2375 } else if (is_young) { 2376 return Normal; 2377 } else { 2378 return Mixed; 2379 } 2380 } 2381 2382 void G1CollectedHeap::collect(GCCause::Cause cause) { 2383 assert_heap_not_locked(); 2384 2385 uint gc_count_before; 2386 uint old_marking_count_before; 2387 uint full_gc_count_before; 2388 bool retry_gc; 2389 2390 do { 2391 retry_gc = false; 2392 2393 { 2394 MutexLocker ml(Heap_lock); 2395 2396 // Read the GC count while holding the Heap_lock 2397 gc_count_before = total_collections(); 2398 full_gc_count_before = total_full_collections(); 2399 old_marking_count_before = _old_marking_cycles_started; 2400 } 2401 2402 if (should_do_concurrent_full_gc(cause)) { 2403 // Schedule an initial-mark evacuation pause that will start a 2404 // concurrent cycle. We're setting word_size to 0 which means that 2405 // we are not requesting a post-GC allocation. 2406 VM_G1IncCollectionPause op(gc_count_before, 2407 0, /* word_size */ 2408 true, /* should_initiate_conc_mark */ 2409 g1_policy()->max_pause_time_ms(), 2410 cause); 2411 op.set_allocation_context(AllocationContext::current()); 2412 2413 VMThread::execute(&op); 2414 if (!op.pause_succeeded()) { 2415 if (old_marking_count_before == _old_marking_cycles_started) { 2416 retry_gc = op.should_retry_gc(); 2417 } else { 2418 // A Full GC happened while we were trying to schedule the 2419 // initial-mark GC. No point in starting a new cycle given 2420 // that the whole heap was collected anyway. 2421 } 2422 2423 if (retry_gc) { 2424 if (GC_locker::is_active_and_needs_gc()) { 2425 GC_locker::stall_until_clear(); 2426 } 2427 } 2428 } 2429 } else { 2430 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2431 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2432 2433 // Schedule a standard evacuation pause. We're setting word_size 2434 // to 0 which means that we are not requesting a post-GC allocation. 2435 VM_G1IncCollectionPause op(gc_count_before, 2436 0, /* word_size */ 2437 false, /* should_initiate_conc_mark */ 2438 g1_policy()->max_pause_time_ms(), 2439 cause); 2440 VMThread::execute(&op); 2441 } else { 2442 // Schedule a Full GC. 2443 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2444 VMThread::execute(&op); 2445 } 2446 } 2447 } while (retry_gc); 2448 } 2449 2450 bool G1CollectedHeap::is_in(const void* p) const { 2451 if (_hrm.reserved().contains(p)) { 2452 // Given that we know that p is in the reserved space, 2453 // heap_region_containing_raw() should successfully 2454 // return the containing region. 2455 HeapRegion* hr = heap_region_containing_raw(p); 2456 return hr->is_in(p); 2457 } else { 2458 return false; 2459 } 2460 } 2461 2462 #ifdef ASSERT 2463 bool G1CollectedHeap::is_in_exact(const void* p) const { 2464 bool contains = reserved_region().contains(p); 2465 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2466 if (contains && available) { 2467 return true; 2468 } else { 2469 return false; 2470 } 2471 } 2472 #endif 2473 2474 // Iteration functions. 2475 2476 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2477 2478 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2479 ExtendedOopClosure* _cl; 2480 public: 2481 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2482 bool doHeapRegion(HeapRegion* r) { 2483 if (!r->is_continues_humongous()) { 2484 r->oop_iterate(_cl); 2485 } 2486 return false; 2487 } 2488 }; 2489 2490 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 2491 IterateOopClosureRegionClosure blk(cl); 2492 heap_region_iterate(&blk); 2493 } 2494 2495 // Iterates an ObjectClosure over all objects within a HeapRegion. 2496 2497 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2498 ObjectClosure* _cl; 2499 public: 2500 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2501 bool doHeapRegion(HeapRegion* r) { 2502 if (!r->is_continues_humongous()) { 2503 r->object_iterate(_cl); 2504 } 2505 return false; 2506 } 2507 }; 2508 2509 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2510 IterateObjectClosureRegionClosure blk(cl); 2511 heap_region_iterate(&blk); 2512 } 2513 2514 // Calls a SpaceClosure on a HeapRegion. 2515 2516 class SpaceClosureRegionClosure: public HeapRegionClosure { 2517 SpaceClosure* _cl; 2518 public: 2519 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} 2520 bool doHeapRegion(HeapRegion* r) { 2521 _cl->do_space(r); 2522 return false; 2523 } 2524 }; 2525 2526 void G1CollectedHeap::space_iterate(SpaceClosure* cl) { 2527 SpaceClosureRegionClosure blk(cl); 2528 heap_region_iterate(&blk); 2529 } 2530 2531 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2532 _hrm.iterate(cl); 2533 } 2534 2535 void 2536 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, 2537 uint worker_id, 2538 HeapRegionClaimer *hrclaimer, 2539 bool concurrent) const { 2540 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); 2541 } 2542 2543 // Clear the cached CSet starting regions and (more importantly) 2544 // the time stamps. Called when we reset the GC time stamp. 2545 void G1CollectedHeap::clear_cset_start_regions() { 2546 assert(_worker_cset_start_region != NULL, "sanity"); 2547 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2548 2549 int n_queues = MAX2((int)ParallelGCThreads, 1); 2550 for (int i = 0; i < n_queues; i++) { 2551 _worker_cset_start_region[i] = NULL; 2552 _worker_cset_start_region_time_stamp[i] = 0; 2553 } 2554 } 2555 2556 // Given the id of a worker, obtain or calculate a suitable 2557 // starting region for iterating over the current collection set. 2558 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2559 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2560 2561 HeapRegion* result = NULL; 2562 unsigned gc_time_stamp = get_gc_time_stamp(); 2563 2564 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2565 // Cached starting region for current worker was set 2566 // during the current pause - so it's valid. 2567 // Note: the cached starting heap region may be NULL 2568 // (when the collection set is empty). 2569 result = _worker_cset_start_region[worker_i]; 2570 assert(result == NULL || result->in_collection_set(), "sanity"); 2571 return result; 2572 } 2573 2574 // The cached entry was not valid so let's calculate 2575 // a suitable starting heap region for this worker. 2576 2577 // We want the parallel threads to start their collection 2578 // set iteration at different collection set regions to 2579 // avoid contention. 2580 // If we have: 2581 // n collection set regions 2582 // p threads 2583 // Then thread t will start at region floor ((t * n) / p) 2584 2585 result = g1_policy()->collection_set(); 2586 uint cs_size = g1_policy()->cset_region_length(); 2587 uint active_workers = workers()->active_workers(); 2588 assert(UseDynamicNumberOfGCThreads || 2589 active_workers == workers()->total_workers(), 2590 "Unless dynamic should use total workers"); 2591 2592 uint end_ind = (cs_size * worker_i) / active_workers; 2593 uint start_ind = 0; 2594 2595 if (worker_i > 0 && 2596 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2597 // Previous workers starting region is valid 2598 // so let's iterate from there 2599 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2600 result = _worker_cset_start_region[worker_i - 1]; 2601 } 2602 2603 for (uint i = start_ind; i < end_ind; i++) { 2604 result = result->next_in_collection_set(); 2605 } 2606 2607 // Note: the calculated starting heap region may be NULL 2608 // (when the collection set is empty). 2609 assert(result == NULL || result->in_collection_set(), "sanity"); 2610 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2611 "should be updated only once per pause"); 2612 _worker_cset_start_region[worker_i] = result; 2613 OrderAccess::storestore(); 2614 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2615 return result; 2616 } 2617 2618 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2619 HeapRegion* r = g1_policy()->collection_set(); 2620 while (r != NULL) { 2621 HeapRegion* next = r->next_in_collection_set(); 2622 if (cl->doHeapRegion(r)) { 2623 cl->incomplete(); 2624 return; 2625 } 2626 r = next; 2627 } 2628 } 2629 2630 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2631 HeapRegionClosure *cl) { 2632 if (r == NULL) { 2633 // The CSet is empty so there's nothing to do. 2634 return; 2635 } 2636 2637 assert(r->in_collection_set(), 2638 "Start region must be a member of the collection set."); 2639 HeapRegion* cur = r; 2640 while (cur != NULL) { 2641 HeapRegion* next = cur->next_in_collection_set(); 2642 if (cl->doHeapRegion(cur) && false) { 2643 cl->incomplete(); 2644 return; 2645 } 2646 cur = next; 2647 } 2648 cur = g1_policy()->collection_set(); 2649 while (cur != r) { 2650 HeapRegion* next = cur->next_in_collection_set(); 2651 if (cl->doHeapRegion(cur) && false) { 2652 cl->incomplete(); 2653 return; 2654 } 2655 cur = next; 2656 } 2657 } 2658 2659 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2660 HeapRegion* result = _hrm.next_region_in_heap(from); 2661 while (result != NULL && result->is_humongous()) { 2662 result = _hrm.next_region_in_heap(result); 2663 } 2664 return result; 2665 } 2666 2667 Space* G1CollectedHeap::space_containing(const void* addr) const { 2668 return heap_region_containing(addr); 2669 } 2670 2671 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2672 Space* sp = space_containing(addr); 2673 return sp->block_start(addr); 2674 } 2675 2676 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2677 Space* sp = space_containing(addr); 2678 return sp->block_size(addr); 2679 } 2680 2681 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2682 Space* sp = space_containing(addr); 2683 return sp->block_is_obj(addr); 2684 } 2685 2686 bool G1CollectedHeap::supports_tlab_allocation() const { 2687 return true; 2688 } 2689 2690 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2691 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2692 } 2693 2694 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2695 return young_list()->eden_used_bytes(); 2696 } 2697 2698 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2699 // must be smaller than the humongous object limit. 2700 size_t G1CollectedHeap::max_tlab_size() const { 2701 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 2702 } 2703 2704 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2705 // Return the remaining space in the cur alloc region, but not less than 2706 // the min TLAB size. 2707 2708 // Also, this value can be at most the humongous object threshold, 2709 // since we can't allow tlabs to grow big enough to accommodate 2710 // humongous objects. 2711 2712 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get(); 2713 size_t max_tlab = max_tlab_size() * wordSize; 2714 if (hr == NULL) { 2715 return max_tlab; 2716 } else { 2717 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 2718 } 2719 } 2720 2721 size_t G1CollectedHeap::max_capacity() const { 2722 return _hrm.reserved().byte_size(); 2723 } 2724 2725 jlong G1CollectedHeap::millis_since_last_gc() { 2726 // assert(false, "NYI"); 2727 return 0; 2728 } 2729 2730 void G1CollectedHeap::prepare_for_verify() { 2731 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2732 ensure_parsability(false); 2733 } 2734 g1_rem_set()->prepare_for_verify(); 2735 } 2736 2737 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 2738 VerifyOption vo) { 2739 switch (vo) { 2740 case VerifyOption_G1UsePrevMarking: 2741 return hr->obj_allocated_since_prev_marking(obj); 2742 case VerifyOption_G1UseNextMarking: 2743 return hr->obj_allocated_since_next_marking(obj); 2744 case VerifyOption_G1UseMarkWord: 2745 return false; 2746 default: 2747 ShouldNotReachHere(); 2748 } 2749 return false; // keep some compilers happy 2750 } 2751 2752 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 2753 switch (vo) { 2754 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 2755 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 2756 case VerifyOption_G1UseMarkWord: return NULL; 2757 default: ShouldNotReachHere(); 2758 } 2759 return NULL; // keep some compilers happy 2760 } 2761 2762 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 2763 switch (vo) { 2764 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 2765 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 2766 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 2767 default: ShouldNotReachHere(); 2768 } 2769 return false; // keep some compilers happy 2770 } 2771 2772 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 2773 switch (vo) { 2774 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 2775 case VerifyOption_G1UseNextMarking: return "NTAMS"; 2776 case VerifyOption_G1UseMarkWord: return "NONE"; 2777 default: ShouldNotReachHere(); 2778 } 2779 return NULL; // keep some compilers happy 2780 } 2781 2782 class VerifyRootsClosure: public OopClosure { 2783 private: 2784 G1CollectedHeap* _g1h; 2785 VerifyOption _vo; 2786 bool _failures; 2787 public: 2788 // _vo == UsePrevMarking -> use "prev" marking information, 2789 // _vo == UseNextMarking -> use "next" marking information, 2790 // _vo == UseMarkWord -> use mark word from object header. 2791 VerifyRootsClosure(VerifyOption vo) : 2792 _g1h(G1CollectedHeap::heap()), 2793 _vo(vo), 2794 _failures(false) { } 2795 2796 bool failures() { return _failures; } 2797 2798 template <class T> void do_oop_nv(T* p) { 2799 T heap_oop = oopDesc::load_heap_oop(p); 2800 if (!oopDesc::is_null(heap_oop)) { 2801 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2802 if (_g1h->is_obj_dead_cond(obj, _vo)) { 2803 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 2804 "points to dead obj "PTR_FORMAT, p, (void*) obj); 2805 if (_vo == VerifyOption_G1UseMarkWord) { 2806 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 2807 } 2808 obj->print_on(gclog_or_tty); 2809 _failures = true; 2810 } 2811 } 2812 } 2813 2814 void do_oop(oop* p) { do_oop_nv(p); } 2815 void do_oop(narrowOop* p) { do_oop_nv(p); } 2816 }; 2817 2818 class G1VerifyCodeRootOopClosure: public OopClosure { 2819 G1CollectedHeap* _g1h; 2820 OopClosure* _root_cl; 2821 nmethod* _nm; 2822 VerifyOption _vo; 2823 bool _failures; 2824 2825 template <class T> void do_oop_work(T* p) { 2826 // First verify that this root is live 2827 _root_cl->do_oop(p); 2828 2829 if (!G1VerifyHeapRegionCodeRoots) { 2830 // We're not verifying the code roots attached to heap region. 2831 return; 2832 } 2833 2834 // Don't check the code roots during marking verification in a full GC 2835 if (_vo == VerifyOption_G1UseMarkWord) { 2836 return; 2837 } 2838 2839 // Now verify that the current nmethod (which contains p) is 2840 // in the code root list of the heap region containing the 2841 // object referenced by p. 2842 2843 T heap_oop = oopDesc::load_heap_oop(p); 2844 if (!oopDesc::is_null(heap_oop)) { 2845 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2846 2847 // Now fetch the region containing the object 2848 HeapRegion* hr = _g1h->heap_region_containing(obj); 2849 HeapRegionRemSet* hrrs = hr->rem_set(); 2850 // Verify that the strong code root list for this region 2851 // contains the nmethod 2852 if (!hrrs->strong_code_roots_list_contains(_nm)) { 2853 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " 2854 "from nmethod "PTR_FORMAT" not in strong " 2855 "code roots for region ["PTR_FORMAT","PTR_FORMAT")", 2856 p, _nm, hr->bottom(), hr->end()); 2857 _failures = true; 2858 } 2859 } 2860 } 2861 2862 public: 2863 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 2864 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 2865 2866 void do_oop(oop* p) { do_oop_work(p); } 2867 void do_oop(narrowOop* p) { do_oop_work(p); } 2868 2869 void set_nmethod(nmethod* nm) { _nm = nm; } 2870 bool failures() { return _failures; } 2871 }; 2872 2873 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 2874 G1VerifyCodeRootOopClosure* _oop_cl; 2875 2876 public: 2877 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 2878 _oop_cl(oop_cl) {} 2879 2880 void do_code_blob(CodeBlob* cb) { 2881 nmethod* nm = cb->as_nmethod_or_null(); 2882 if (nm != NULL) { 2883 _oop_cl->set_nmethod(nm); 2884 nm->oops_do(_oop_cl); 2885 } 2886 } 2887 }; 2888 2889 class YoungRefCounterClosure : public OopClosure { 2890 G1CollectedHeap* _g1h; 2891 int _count; 2892 public: 2893 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 2894 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 2895 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 2896 2897 int count() { return _count; } 2898 void reset_count() { _count = 0; }; 2899 }; 2900 2901 class VerifyKlassClosure: public KlassClosure { 2902 YoungRefCounterClosure _young_ref_counter_closure; 2903 OopClosure *_oop_closure; 2904 public: 2905 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 2906 void do_klass(Klass* k) { 2907 k->oops_do(_oop_closure); 2908 2909 _young_ref_counter_closure.reset_count(); 2910 k->oops_do(&_young_ref_counter_closure); 2911 if (_young_ref_counter_closure.count() > 0) { 2912 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k)); 2913 } 2914 } 2915 }; 2916 2917 class VerifyLivenessOopClosure: public OopClosure { 2918 G1CollectedHeap* _g1h; 2919 VerifyOption _vo; 2920 public: 2921 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 2922 _g1h(g1h), _vo(vo) 2923 { } 2924 void do_oop(narrowOop *p) { do_oop_work(p); } 2925 void do_oop( oop *p) { do_oop_work(p); } 2926 2927 template <class T> void do_oop_work(T *p) { 2928 oop obj = oopDesc::load_decode_heap_oop(p); 2929 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 2930 "Dead object referenced by a not dead object"); 2931 } 2932 }; 2933 2934 class VerifyObjsInRegionClosure: public ObjectClosure { 2935 private: 2936 G1CollectedHeap* _g1h; 2937 size_t _live_bytes; 2938 HeapRegion *_hr; 2939 VerifyOption _vo; 2940 public: 2941 // _vo == UsePrevMarking -> use "prev" marking information, 2942 // _vo == UseNextMarking -> use "next" marking information, 2943 // _vo == UseMarkWord -> use mark word from object header. 2944 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 2945 : _live_bytes(0), _hr(hr), _vo(vo) { 2946 _g1h = G1CollectedHeap::heap(); 2947 } 2948 void do_object(oop o) { 2949 VerifyLivenessOopClosure isLive(_g1h, _vo); 2950 assert(o != NULL, "Huh?"); 2951 if (!_g1h->is_obj_dead_cond(o, _vo)) { 2952 // If the object is alive according to the mark word, 2953 // then verify that the marking information agrees. 2954 // Note we can't verify the contra-positive of the 2955 // above: if the object is dead (according to the mark 2956 // word), it may not be marked, or may have been marked 2957 // but has since became dead, or may have been allocated 2958 // since the last marking. 2959 if (_vo == VerifyOption_G1UseMarkWord) { 2960 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 2961 } 2962 2963 o->oop_iterate_no_header(&isLive); 2964 if (!_hr->obj_allocated_since_prev_marking(o)) { 2965 size_t obj_size = o->size(); // Make sure we don't overflow 2966 _live_bytes += (obj_size * HeapWordSize); 2967 } 2968 } 2969 } 2970 size_t live_bytes() { return _live_bytes; } 2971 }; 2972 2973 class PrintObjsInRegionClosure : public ObjectClosure { 2974 HeapRegion *_hr; 2975 G1CollectedHeap *_g1; 2976 public: 2977 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 2978 _g1 = G1CollectedHeap::heap(); 2979 }; 2980 2981 void do_object(oop o) { 2982 if (o != NULL) { 2983 HeapWord *start = (HeapWord *) o; 2984 size_t word_sz = o->size(); 2985 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 2986 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 2987 (void*) o, word_sz, 2988 _g1->isMarkedPrev(o), 2989 _g1->isMarkedNext(o), 2990 _hr->obj_allocated_since_prev_marking(o)); 2991 HeapWord *end = start + word_sz; 2992 HeapWord *cur; 2993 int *val; 2994 for (cur = start; cur < end; cur++) { 2995 val = (int *) cur; 2996 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val); 2997 } 2998 } 2999 } 3000 }; 3001 3002 class VerifyRegionClosure: public HeapRegionClosure { 3003 private: 3004 bool _par; 3005 VerifyOption _vo; 3006 bool _failures; 3007 public: 3008 // _vo == UsePrevMarking -> use "prev" marking information, 3009 // _vo == UseNextMarking -> use "next" marking information, 3010 // _vo == UseMarkWord -> use mark word from object header. 3011 VerifyRegionClosure(bool par, VerifyOption vo) 3012 : _par(par), 3013 _vo(vo), 3014 _failures(false) {} 3015 3016 bool failures() { 3017 return _failures; 3018 } 3019 3020 bool doHeapRegion(HeapRegion* r) { 3021 if (!r->is_continues_humongous()) { 3022 bool failures = false; 3023 r->verify(_vo, &failures); 3024 if (failures) { 3025 _failures = true; 3026 } else { 3027 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3028 r->object_iterate(¬_dead_yet_cl); 3029 if (_vo != VerifyOption_G1UseNextMarking) { 3030 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3031 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 3032 "max_live_bytes "SIZE_FORMAT" " 3033 "< calculated "SIZE_FORMAT, 3034 r->bottom(), r->end(), 3035 r->max_live_bytes(), 3036 not_dead_yet_cl.live_bytes()); 3037 _failures = true; 3038 } 3039 } else { 3040 // When vo == UseNextMarking we cannot currently do a sanity 3041 // check on the live bytes as the calculation has not been 3042 // finalized yet. 3043 } 3044 } 3045 } 3046 return false; // stop the region iteration if we hit a failure 3047 } 3048 }; 3049 3050 // This is the task used for parallel verification of the heap regions 3051 3052 class G1ParVerifyTask: public AbstractGangTask { 3053 private: 3054 G1CollectedHeap* _g1h; 3055 VerifyOption _vo; 3056 bool _failures; 3057 HeapRegionClaimer _hrclaimer; 3058 3059 public: 3060 // _vo == UsePrevMarking -> use "prev" marking information, 3061 // _vo == UseNextMarking -> use "next" marking information, 3062 // _vo == UseMarkWord -> use mark word from object header. 3063 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3064 AbstractGangTask("Parallel verify task"), 3065 _g1h(g1h), 3066 _vo(vo), 3067 _failures(false), 3068 _hrclaimer(g1h->workers()->active_workers()) {} 3069 3070 bool failures() { 3071 return _failures; 3072 } 3073 3074 void work(uint worker_id) { 3075 HandleMark hm; 3076 VerifyRegionClosure blk(true, _vo); 3077 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer); 3078 if (blk.failures()) { 3079 _failures = true; 3080 } 3081 } 3082 }; 3083 3084 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3085 if (SafepointSynchronize::is_at_safepoint()) { 3086 assert(Thread::current()->is_VM_thread(), 3087 "Expected to be executed serially by the VM thread at this point"); 3088 3089 if (!silent) { gclog_or_tty->print("Roots "); } 3090 VerifyRootsClosure rootsCl(vo); 3091 VerifyKlassClosure klassCl(this, &rootsCl); 3092 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3093 3094 // We apply the relevant closures to all the oops in the 3095 // system dictionary, class loader data graph, the string table 3096 // and the nmethods in the code cache. 3097 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3098 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3099 3100 { 3101 G1RootProcessor root_processor(this); 3102 root_processor.process_all_roots(&rootsCl, 3103 &cldCl, 3104 &blobsCl); 3105 } 3106 3107 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3108 3109 if (vo != VerifyOption_G1UseMarkWord) { 3110 // If we're verifying during a full GC then the region sets 3111 // will have been torn down at the start of the GC. Therefore 3112 // verifying the region sets will fail. So we only verify 3113 // the region sets when not in a full GC. 3114 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3115 verify_region_sets(); 3116 } 3117 3118 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3119 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3120 3121 G1ParVerifyTask task(this, vo); 3122 assert(UseDynamicNumberOfGCThreads || 3123 workers()->active_workers() == workers()->total_workers(), 3124 "If not dynamic should be using all the workers"); 3125 int n_workers = workers()->active_workers(); 3126 set_par_threads(n_workers); 3127 workers()->run_task(&task); 3128 set_par_threads(0); 3129 if (task.failures()) { 3130 failures = true; 3131 } 3132 3133 } else { 3134 VerifyRegionClosure blk(false, vo); 3135 heap_region_iterate(&blk); 3136 if (blk.failures()) { 3137 failures = true; 3138 } 3139 } 3140 3141 if (G1StringDedup::is_enabled()) { 3142 if (!silent) gclog_or_tty->print("StrDedup "); 3143 G1StringDedup::verify(); 3144 } 3145 3146 if (failures) { 3147 gclog_or_tty->print_cr("Heap:"); 3148 // It helps to have the per-region information in the output to 3149 // help us track down what went wrong. This is why we call 3150 // print_extended_on() instead of print_on(). 3151 print_extended_on(gclog_or_tty); 3152 gclog_or_tty->cr(); 3153 #ifndef PRODUCT 3154 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 3155 concurrent_mark()->print_reachable("at-verification-failure", 3156 vo, false /* all */); 3157 } 3158 #endif 3159 gclog_or_tty->flush(); 3160 } 3161 guarantee(!failures, "there should not have been any failures"); 3162 } else { 3163 if (!silent) { 3164 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3165 if (G1StringDedup::is_enabled()) { 3166 gclog_or_tty->print(", StrDedup"); 3167 } 3168 gclog_or_tty->print(") "); 3169 } 3170 } 3171 } 3172 3173 void G1CollectedHeap::verify(bool silent) { 3174 verify(silent, VerifyOption_G1UsePrevMarking); 3175 } 3176 3177 double G1CollectedHeap::verify(bool guard, const char* msg) { 3178 double verify_time_ms = 0.0; 3179 3180 if (guard && total_collections() >= VerifyGCStartAt) { 3181 double verify_start = os::elapsedTime(); 3182 HandleMark hm; // Discard invalid handles created during verification 3183 prepare_for_verify(); 3184 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3185 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3186 } 3187 3188 return verify_time_ms; 3189 } 3190 3191 void G1CollectedHeap::verify_before_gc() { 3192 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3193 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3194 } 3195 3196 void G1CollectedHeap::verify_after_gc() { 3197 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3198 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3199 } 3200 3201 class PrintRegionClosure: public HeapRegionClosure { 3202 outputStream* _st; 3203 public: 3204 PrintRegionClosure(outputStream* st) : _st(st) {} 3205 bool doHeapRegion(HeapRegion* r) { 3206 r->print_on(_st); 3207 return false; 3208 } 3209 }; 3210 3211 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3212 const HeapRegion* hr, 3213 const VerifyOption vo) const { 3214 switch (vo) { 3215 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3216 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3217 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3218 default: ShouldNotReachHere(); 3219 } 3220 return false; // keep some compilers happy 3221 } 3222 3223 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3224 const VerifyOption vo) const { 3225 switch (vo) { 3226 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3227 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3228 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3229 default: ShouldNotReachHere(); 3230 } 3231 return false; // keep some compilers happy 3232 } 3233 3234 void G1CollectedHeap::print_on(outputStream* st) const { 3235 st->print(" %-20s", "garbage-first heap"); 3236 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3237 capacity()/K, used_unlocked()/K); 3238 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3239 _hrm.reserved().start(), 3240 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords, 3241 _hrm.reserved().end()); 3242 st->cr(); 3243 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3244 uint young_regions = _young_list->length(); 3245 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3246 (size_t) young_regions * HeapRegion::GrainBytes / K); 3247 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3248 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3249 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3250 st->cr(); 3251 MetaspaceAux::print_on(st); 3252 } 3253 3254 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3255 print_on(st); 3256 3257 // Print the per-region information. 3258 st->cr(); 3259 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3260 "HS=humongous(starts), HC=humongous(continues), " 3261 "CS=collection set, F=free, TS=gc time stamp, " 3262 "PTAMS=previous top-at-mark-start, " 3263 "NTAMS=next top-at-mark-start)"); 3264 PrintRegionClosure blk(st); 3265 heap_region_iterate(&blk); 3266 } 3267 3268 void G1CollectedHeap::print_on_error(outputStream* st) const { 3269 this->CollectedHeap::print_on_error(st); 3270 3271 if (_cm != NULL) { 3272 st->cr(); 3273 _cm->print_on_error(st); 3274 } 3275 } 3276 3277 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3278 workers()->print_worker_threads_on(st); 3279 _cmThread->print_on(st); 3280 st->cr(); 3281 _cm->print_worker_threads_on(st); 3282 _cg1r->print_worker_threads_on(st); 3283 if (G1StringDedup::is_enabled()) { 3284 G1StringDedup::print_worker_threads_on(st); 3285 } 3286 } 3287 3288 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3289 workers()->threads_do(tc); 3290 tc->do_thread(_cmThread); 3291 _cg1r->threads_do(tc); 3292 if (G1StringDedup::is_enabled()) { 3293 G1StringDedup::threads_do(tc); 3294 } 3295 } 3296 3297 void G1CollectedHeap::print_tracing_info() const { 3298 // We'll overload this to mean "trace GC pause statistics." 3299 if (TraceYoungGenTime || TraceOldGenTime) { 3300 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3301 // to that. 3302 g1_policy()->print_tracing_info(); 3303 } 3304 if (G1SummarizeRSetStats) { 3305 g1_rem_set()->print_summary_info(); 3306 } 3307 if (G1SummarizeConcMark) { 3308 concurrent_mark()->print_summary_info(); 3309 } 3310 g1_policy()->print_yg_surv_rate_info(); 3311 } 3312 3313 #ifndef PRODUCT 3314 // Helpful for debugging RSet issues. 3315 3316 class PrintRSetsClosure : public HeapRegionClosure { 3317 private: 3318 const char* _msg; 3319 size_t _occupied_sum; 3320 3321 public: 3322 bool doHeapRegion(HeapRegion* r) { 3323 HeapRegionRemSet* hrrs = r->rem_set(); 3324 size_t occupied = hrrs->occupied(); 3325 _occupied_sum += occupied; 3326 3327 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3328 HR_FORMAT_PARAMS(r)); 3329 if (occupied == 0) { 3330 gclog_or_tty->print_cr(" RSet is empty"); 3331 } else { 3332 hrrs->print(); 3333 } 3334 gclog_or_tty->print_cr("----------"); 3335 return false; 3336 } 3337 3338 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3339 gclog_or_tty->cr(); 3340 gclog_or_tty->print_cr("========================================"); 3341 gclog_or_tty->print_cr("%s", msg); 3342 gclog_or_tty->cr(); 3343 } 3344 3345 ~PrintRSetsClosure() { 3346 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3347 gclog_or_tty->print_cr("========================================"); 3348 gclog_or_tty->cr(); 3349 } 3350 }; 3351 3352 void G1CollectedHeap::print_cset_rsets() { 3353 PrintRSetsClosure cl("Printing CSet RSets"); 3354 collection_set_iterate(&cl); 3355 } 3356 3357 void G1CollectedHeap::print_all_rsets() { 3358 PrintRSetsClosure cl("Printing All RSets");; 3359 heap_region_iterate(&cl); 3360 } 3361 #endif // PRODUCT 3362 3363 G1CollectedHeap* G1CollectedHeap::heap() { 3364 assert(_sh->kind() == CollectedHeap::G1CollectedHeap, 3365 "not a garbage-first heap"); 3366 return _g1h; 3367 } 3368 3369 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3370 // always_do_update_barrier = false; 3371 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3372 // Fill TLAB's and such 3373 accumulate_statistics_all_tlabs(); 3374 ensure_parsability(true); 3375 3376 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3377 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3378 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3379 } 3380 } 3381 3382 void G1CollectedHeap::gc_epilogue(bool full) { 3383 3384 if (G1SummarizeRSetStats && 3385 (G1SummarizeRSetStatsPeriod > 0) && 3386 // we are at the end of the GC. Total collections has already been increased. 3387 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3388 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3389 } 3390 3391 // FIXME: what is this about? 3392 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3393 // is set. 3394 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3395 "derived pointer present")); 3396 // always_do_update_barrier = true; 3397 3398 resize_all_tlabs(); 3399 allocation_context_stats().update(full); 3400 3401 // We have just completed a GC. Update the soft reference 3402 // policy with the new heap occupancy 3403 Universe::update_heap_info_at_gc(); 3404 } 3405 3406 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3407 uint gc_count_before, 3408 bool* succeeded, 3409 GCCause::Cause gc_cause, 3410 uint gc_attempt) { 3411 assert_heap_not_locked_and_not_at_safepoint(); 3412 g1_policy()->record_stop_world_start(); 3413 VM_G1IncCollectionPause op(gc_count_before, 3414 word_size, 3415 false, /* should_initiate_conc_mark */ 3416 g1_policy()->max_pause_time_ms(), 3417 gc_cause, 3418 gc_attempt); 3419 3420 op.set_allocation_context(AllocationContext::current()); 3421 VMThread::execute(&op); 3422 3423 HeapWord* result = op.result(); 3424 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3425 assert(result == NULL || ret_succeeded, 3426 "the result should be NULL if the VM did not succeed"); 3427 *succeeded = ret_succeeded; 3428 3429 assert_heap_not_locked(); 3430 return result; 3431 } 3432 3433 void 3434 G1CollectedHeap::doConcurrentMark() { 3435 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3436 if (!_cmThread->in_progress()) { 3437 _cmThread->set_started(); 3438 CGC_lock->notify(); 3439 } 3440 } 3441 3442 size_t G1CollectedHeap::pending_card_num() { 3443 size_t extra_cards = 0; 3444 JavaThread *curr = Threads::first(); 3445 while (curr != NULL) { 3446 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3447 extra_cards += dcq.size(); 3448 curr = curr->next(); 3449 } 3450 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3451 size_t buffer_size = dcqs.buffer_size(); 3452 size_t buffer_num = dcqs.completed_buffers_num(); 3453 3454 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3455 // in bytes - not the number of 'entries'. We need to convert 3456 // into a number of cards. 3457 return (buffer_size * buffer_num + extra_cards) / oopSize; 3458 } 3459 3460 size_t G1CollectedHeap::cards_scanned() { 3461 return g1_rem_set()->cardsScanned(); 3462 } 3463 3464 bool G1CollectedHeap::humongous_region_is_always_live(uint index) { 3465 HeapRegion* region = region_at(index); 3466 assert(region->is_starts_humongous(), "Must start a humongous object"); 3467 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty(); 3468 } 3469 3470 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3471 private: 3472 size_t _total_humongous; 3473 size_t _candidate_humongous; 3474 3475 DirtyCardQueue _dcq; 3476 3477 bool humongous_region_is_candidate(uint index) { 3478 HeapRegion* region = G1CollectedHeap::heap()->region_at(index); 3479 assert(region->is_starts_humongous(), "Must start a humongous object"); 3480 HeapRegionRemSet* const rset = region->rem_set(); 3481 bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs; 3482 return !oop(region->bottom())->is_objArray() && 3483 ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) || 3484 (!allow_stale_refs && rset->is_empty())); 3485 } 3486 3487 public: 3488 RegisterHumongousWithInCSetFastTestClosure() 3489 : _total_humongous(0), 3490 _candidate_humongous(0), 3491 _dcq(&JavaThread::dirty_card_queue_set()) { 3492 } 3493 3494 virtual bool doHeapRegion(HeapRegion* r) { 3495 if (!r->is_starts_humongous()) { 3496 return false; 3497 } 3498 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3499 3500 uint region_idx = r->hrm_index(); 3501 bool is_candidate = humongous_region_is_candidate(region_idx); 3502 // Is_candidate already filters out humongous object with large remembered sets. 3503 // If we have a humongous object with a few remembered sets, we simply flush these 3504 // remembered set entries into the DCQS. That will result in automatic 3505 // re-evaluation of their remembered set entries during the following evacuation 3506 // phase. 3507 if (is_candidate) { 3508 if (!r->rem_set()->is_empty()) { 3509 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 3510 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 3511 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 3512 HeapRegionRemSetIterator hrrs(r->rem_set()); 3513 size_t card_index; 3514 while (hrrs.has_next(card_index)) { 3515 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 3516 // The remembered set might contain references to already freed 3517 // regions. Filter out such entries to avoid failing card table 3518 // verification. 3519 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) { 3520 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 3521 *card_ptr = CardTableModRefBS::dirty_card_val(); 3522 _dcq.enqueue(card_ptr); 3523 } 3524 } 3525 } 3526 r->rem_set()->clear_locked(); 3527 } 3528 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 3529 g1h->register_humongous_region_with_cset(region_idx); 3530 _candidate_humongous++; 3531 } 3532 _total_humongous++; 3533 3534 return false; 3535 } 3536 3537 size_t total_humongous() const { return _total_humongous; } 3538 size_t candidate_humongous() const { return _candidate_humongous; } 3539 3540 void flush_rem_set_entries() { _dcq.flush(); } 3541 }; 3542 3543 void G1CollectedHeap::register_humongous_regions_with_cset() { 3544 if (!G1EagerReclaimHumongousObjects) { 3545 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 3546 return; 3547 } 3548 double time = os::elapsed_counter(); 3549 3550 RegisterHumongousWithInCSetFastTestClosure cl; 3551 heap_region_iterate(&cl); 3552 3553 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 3554 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 3555 cl.total_humongous(), 3556 cl.candidate_humongous()); 3557 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3558 3559 if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) { 3560 clear_humongous_is_live_table(); 3561 } 3562 3563 // Finally flush all remembered set entries to re-check into the global DCQS. 3564 cl.flush_rem_set_entries(); 3565 } 3566 3567 void 3568 G1CollectedHeap::setup_surviving_young_words() { 3569 assert(_surviving_young_words == NULL, "pre-condition"); 3570 uint array_length = g1_policy()->young_cset_region_length(); 3571 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3572 if (_surviving_young_words == NULL) { 3573 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3574 "Not enough space for young surv words summary."); 3575 } 3576 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3577 #ifdef ASSERT 3578 for (uint i = 0; i < array_length; ++i) { 3579 assert( _surviving_young_words[i] == 0, "memset above" ); 3580 } 3581 #endif // !ASSERT 3582 } 3583 3584 void 3585 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3586 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3587 uint array_length = g1_policy()->young_cset_region_length(); 3588 for (uint i = 0; i < array_length; ++i) { 3589 _surviving_young_words[i] += surv_young_words[i]; 3590 } 3591 } 3592 3593 void 3594 G1CollectedHeap::cleanup_surviving_young_words() { 3595 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3596 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words); 3597 _surviving_young_words = NULL; 3598 } 3599 3600 #ifdef ASSERT 3601 class VerifyCSetClosure: public HeapRegionClosure { 3602 public: 3603 bool doHeapRegion(HeapRegion* hr) { 3604 // Here we check that the CSet region's RSet is ready for parallel 3605 // iteration. The fields that we'll verify are only manipulated 3606 // when the region is part of a CSet and is collected. Afterwards, 3607 // we reset these fields when we clear the region's RSet (when the 3608 // region is freed) so they are ready when the region is 3609 // re-allocated. The only exception to this is if there's an 3610 // evacuation failure and instead of freeing the region we leave 3611 // it in the heap. In that case, we reset these fields during 3612 // evacuation failure handling. 3613 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3614 3615 // Here's a good place to add any other checks we'd like to 3616 // perform on CSet regions. 3617 return false; 3618 } 3619 }; 3620 #endif // ASSERT 3621 3622 #if TASKQUEUE_STATS 3623 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3624 st->print_raw_cr("GC Task Stats"); 3625 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3626 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3627 } 3628 3629 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3630 print_taskqueue_stats_hdr(st); 3631 3632 TaskQueueStats totals; 3633 const int n = workers()->total_workers(); 3634 for (int i = 0; i < n; ++i) { 3635 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3636 totals += task_queue(i)->stats; 3637 } 3638 st->print_raw("tot "); totals.print(st); st->cr(); 3639 3640 DEBUG_ONLY(totals.verify()); 3641 } 3642 3643 void G1CollectedHeap::reset_taskqueue_stats() { 3644 const int n = workers()->total_workers(); 3645 for (int i = 0; i < n; ++i) { 3646 task_queue(i)->stats.reset(); 3647 } 3648 } 3649 #endif // TASKQUEUE_STATS 3650 3651 void G1CollectedHeap::log_gc_header() { 3652 if (!G1Log::fine()) { 3653 return; 3654 } 3655 3656 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id()); 3657 3658 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3659 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") 3660 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3661 3662 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3663 } 3664 3665 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3666 if (!G1Log::fine()) { 3667 return; 3668 } 3669 3670 if (G1Log::finer()) { 3671 if (evacuation_failed()) { 3672 gclog_or_tty->print(" (to-space exhausted)"); 3673 } 3674 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3675 g1_policy()->phase_times()->note_gc_end(); 3676 g1_policy()->phase_times()->print(pause_time_sec); 3677 g1_policy()->print_detailed_heap_transition(); 3678 } else { 3679 if (evacuation_failed()) { 3680 gclog_or_tty->print("--"); 3681 } 3682 g1_policy()->print_heap_transition(); 3683 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3684 } 3685 gclog_or_tty->flush(); 3686 } 3687 3688 bool 3689 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3690 assert_at_safepoint(true /* should_be_vm_thread */); 3691 guarantee(!is_gc_active(), "collection is not reentrant"); 3692 3693 if (GC_locker::check_active_before_gc()) { 3694 return false; 3695 } 3696 3697 _gc_timer_stw->register_gc_start(); 3698 3699 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3700 3701 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3702 ResourceMark rm; 3703 3704 print_heap_before_gc(); 3705 trace_heap_before_gc(_gc_tracer_stw); 3706 3707 verify_region_sets_optional(); 3708 verify_dirty_young_regions(); 3709 3710 // This call will decide whether this pause is an initial-mark 3711 // pause. If it is, during_initial_mark_pause() will return true 3712 // for the duration of this pause. 3713 g1_policy()->decide_on_conc_mark_initiation(); 3714 3715 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3716 assert(!g1_policy()->during_initial_mark_pause() || 3717 g1_policy()->gcs_are_young(), "sanity"); 3718 3719 // We also do not allow mixed GCs during marking. 3720 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3721 3722 // Record whether this pause is an initial mark. When the current 3723 // thread has completed its logging output and it's safe to signal 3724 // the CM thread, the flag's value in the policy has been reset. 3725 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3726 3727 // Inner scope for scope based logging, timers, and stats collection 3728 { 3729 EvacuationInfo evacuation_info; 3730 3731 if (g1_policy()->during_initial_mark_pause()) { 3732 // We are about to start a marking cycle, so we increment the 3733 // full collection counter. 3734 increment_old_marking_cycles_started(); 3735 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3736 } 3737 3738 _gc_tracer_stw->report_yc_type(yc_type()); 3739 3740 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3741 3742 uint active_workers = workers()->active_workers(); 3743 double pause_start_sec = os::elapsedTime(); 3744 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress()); 3745 log_gc_header(); 3746 3747 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3748 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3749 3750 // If the secondary_free_list is not empty, append it to the 3751 // free_list. No need to wait for the cleanup operation to finish; 3752 // the region allocation code will check the secondary_free_list 3753 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3754 // set, skip this step so that the region allocation code has to 3755 // get entries from the secondary_free_list. 3756 if (!G1StressConcRegionFreeing) { 3757 append_secondary_free_list_if_not_empty_with_lock(); 3758 } 3759 3760 assert(check_young_list_well_formed(), "young list should be well formed"); 3761 3762 // Don't dynamically change the number of GC threads this early. A value of 3763 // 0 is used to indicate serial work. When parallel work is done, 3764 // it will be set. 3765 3766 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3767 IsGCActiveMark x; 3768 3769 gc_prologue(false); 3770 increment_total_collections(false /* full gc */); 3771 increment_gc_time_stamp(); 3772 3773 verify_before_gc(); 3774 3775 check_bitmaps("GC Start"); 3776 3777 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3778 3779 // Please see comment in g1CollectedHeap.hpp and 3780 // G1CollectedHeap::ref_processing_init() to see how 3781 // reference processing currently works in G1. 3782 3783 // Enable discovery in the STW reference processor 3784 ref_processor_stw()->enable_discovery(); 3785 3786 { 3787 // We want to temporarily turn off discovery by the 3788 // CM ref processor, if necessary, and turn it back on 3789 // on again later if we do. Using a scoped 3790 // NoRefDiscovery object will do this. 3791 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3792 3793 // Forget the current alloc region (we might even choose it to be part 3794 // of the collection set!). 3795 _allocator->release_mutator_alloc_region(); 3796 3797 // We should call this after we retire the mutator alloc 3798 // region(s) so that all the ALLOC / RETIRE events are generated 3799 // before the start GC event. 3800 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3801 3802 // This timing is only used by the ergonomics to handle our pause target. 3803 // It is unclear why this should not include the full pause. We will 3804 // investigate this in CR 7178365. 3805 // 3806 // Preserving the old comment here if that helps the investigation: 3807 // 3808 // The elapsed time induced by the start time below deliberately elides 3809 // the possible verification above. 3810 double sample_start_time_sec = os::elapsedTime(); 3811 3812 #if YOUNG_LIST_VERBOSE 3813 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 3814 _young_list->print(); 3815 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3816 #endif // YOUNG_LIST_VERBOSE 3817 3818 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3819 3820 double scan_wait_start = os::elapsedTime(); 3821 // We have to wait until the CM threads finish scanning the 3822 // root regions as it's the only way to ensure that all the 3823 // objects on them have been correctly scanned before we start 3824 // moving them during the GC. 3825 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3826 double wait_time_ms = 0.0; 3827 if (waited) { 3828 double scan_wait_end = os::elapsedTime(); 3829 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3830 } 3831 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3832 3833 #if YOUNG_LIST_VERBOSE 3834 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 3835 _young_list->print(); 3836 #endif // YOUNG_LIST_VERBOSE 3837 3838 if (g1_policy()->during_initial_mark_pause()) { 3839 concurrent_mark()->checkpointRootsInitialPre(); 3840 } 3841 3842 #if YOUNG_LIST_VERBOSE 3843 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 3844 _young_list->print(); 3845 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3846 #endif // YOUNG_LIST_VERBOSE 3847 3848 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 3849 3850 register_humongous_regions_with_cset(); 3851 3852 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3853 3854 _cm->note_start_of_gc(); 3855 // We should not verify the per-thread SATB buffers given that 3856 // we have not filtered them yet (we'll do so during the 3857 // GC). We also call this after finalize_cset() to 3858 // ensure that the CSet has been finalized. 3859 _cm->verify_no_cset_oops(true /* verify_stacks */, 3860 true /* verify_enqueued_buffers */, 3861 false /* verify_thread_buffers */, 3862 true /* verify_fingers */); 3863 3864 if (_hr_printer.is_active()) { 3865 HeapRegion* hr = g1_policy()->collection_set(); 3866 while (hr != NULL) { 3867 _hr_printer.cset(hr); 3868 hr = hr->next_in_collection_set(); 3869 } 3870 } 3871 3872 #ifdef ASSERT 3873 VerifyCSetClosure cl; 3874 collection_set_iterate(&cl); 3875 #endif // ASSERT 3876 3877 setup_surviving_young_words(); 3878 3879 // Initialize the GC alloc regions. 3880 _allocator->init_gc_alloc_regions(evacuation_info); 3881 3882 // Actually do the work... 3883 evacuate_collection_set(evacuation_info); 3884 3885 // We do this to mainly verify the per-thread SATB buffers 3886 // (which have been filtered by now) since we didn't verify 3887 // them earlier. No point in re-checking the stacks / enqueued 3888 // buffers given that the CSet has not changed since last time 3889 // we checked. 3890 _cm->verify_no_cset_oops(false /* verify_stacks */, 3891 false /* verify_enqueued_buffers */, 3892 true /* verify_thread_buffers */, 3893 true /* verify_fingers */); 3894 3895 free_collection_set(g1_policy()->collection_set(), evacuation_info); 3896 3897 eagerly_reclaim_humongous_regions(); 3898 3899 g1_policy()->clear_collection_set(); 3900 3901 cleanup_surviving_young_words(); 3902 3903 // Start a new incremental collection set for the next pause. 3904 g1_policy()->start_incremental_cset_building(); 3905 3906 clear_cset_fast_test(); 3907 3908 _young_list->reset_sampled_info(); 3909 3910 // Don't check the whole heap at this point as the 3911 // GC alloc regions from this pause have been tagged 3912 // as survivors and moved on to the survivor list. 3913 // Survivor regions will fail the !is_young() check. 3914 assert(check_young_list_empty(false /* check_heap */), 3915 "young list should be empty"); 3916 3917 #if YOUNG_LIST_VERBOSE 3918 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 3919 _young_list->print(); 3920 #endif // YOUNG_LIST_VERBOSE 3921 3922 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 3923 _young_list->first_survivor_region(), 3924 _young_list->last_survivor_region()); 3925 3926 _young_list->reset_auxilary_lists(); 3927 3928 if (evacuation_failed()) { 3929 _allocator->set_used(recalculate_used()); 3930 uint n_queues = MAX2((int)ParallelGCThreads, 1); 3931 for (uint i = 0; i < n_queues; i++) { 3932 if (_evacuation_failed_info_array[i].has_failed()) { 3933 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3934 } 3935 } 3936 } else { 3937 // The "used" of the the collection set have already been subtracted 3938 // when they were freed. Add in the bytes evacuated. 3939 _allocator->increase_used(g1_policy()->bytes_copied_during_gc()); 3940 } 3941 3942 if (g1_policy()->during_initial_mark_pause()) { 3943 // We have to do this before we notify the CM threads that 3944 // they can start working to make sure that all the 3945 // appropriate initialization is done on the CM object. 3946 concurrent_mark()->checkpointRootsInitialPost(); 3947 set_marking_started(); 3948 // Note that we don't actually trigger the CM thread at 3949 // this point. We do that later when we're sure that 3950 // the current thread has completed its logging output. 3951 } 3952 3953 allocate_dummy_regions(); 3954 3955 #if YOUNG_LIST_VERBOSE 3956 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 3957 _young_list->print(); 3958 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3959 #endif // YOUNG_LIST_VERBOSE 3960 3961 _allocator->init_mutator_alloc_region(); 3962 3963 { 3964 size_t expand_bytes = g1_policy()->expansion_amount(); 3965 if (expand_bytes > 0) { 3966 size_t bytes_before = capacity(); 3967 // No need for an ergo verbose message here, 3968 // expansion_amount() does this when it returns a value > 0. 3969 if (!expand(expand_bytes)) { 3970 // We failed to expand the heap. Cannot do anything about it. 3971 } 3972 } 3973 } 3974 3975 // We redo the verification but now wrt to the new CSet which 3976 // has just got initialized after the previous CSet was freed. 3977 _cm->verify_no_cset_oops(true /* verify_stacks */, 3978 true /* verify_enqueued_buffers */, 3979 true /* verify_thread_buffers */, 3980 true /* verify_fingers */); 3981 _cm->note_end_of_gc(); 3982 3983 // This timing is only used by the ergonomics to handle our pause target. 3984 // It is unclear why this should not include the full pause. We will 3985 // investigate this in CR 7178365. 3986 double sample_end_time_sec = os::elapsedTime(); 3987 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3988 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 3989 3990 MemoryService::track_memory_usage(); 3991 3992 // In prepare_for_verify() below we'll need to scan the deferred 3993 // update buffers to bring the RSets up-to-date if 3994 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 3995 // the update buffers we'll probably need to scan cards on the 3996 // regions we just allocated to (i.e., the GC alloc 3997 // regions). However, during the last GC we called 3998 // set_saved_mark() on all the GC alloc regions, so card 3999 // scanning might skip the [saved_mark_word()...top()] area of 4000 // those regions (i.e., the area we allocated objects into 4001 // during the last GC). But it shouldn't. Given that 4002 // saved_mark_word() is conditional on whether the GC time stamp 4003 // on the region is current or not, by incrementing the GC time 4004 // stamp here we invalidate all the GC time stamps on all the 4005 // regions and saved_mark_word() will simply return top() for 4006 // all the regions. This is a nicer way of ensuring this rather 4007 // than iterating over the regions and fixing them. In fact, the 4008 // GC time stamp increment here also ensures that 4009 // saved_mark_word() will return top() between pauses, i.e., 4010 // during concurrent refinement. So we don't need the 4011 // is_gc_active() check to decided which top to use when 4012 // scanning cards (see CR 7039627). 4013 increment_gc_time_stamp(); 4014 4015 verify_after_gc(); 4016 check_bitmaps("GC End"); 4017 4018 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4019 ref_processor_stw()->verify_no_references_recorded(); 4020 4021 // CM reference discovery will be re-enabled if necessary. 4022 } 4023 4024 // We should do this after we potentially expand the heap so 4025 // that all the COMMIT events are generated before the end GC 4026 // event, and after we retire the GC alloc regions so that all 4027 // RETIRE events are generated before the end GC event. 4028 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4029 4030 #ifdef TRACESPINNING 4031 ParallelTaskTerminator::print_termination_counts(); 4032 #endif 4033 4034 gc_epilogue(false); 4035 } 4036 4037 // Print the remainder of the GC log output. 4038 log_gc_footer(os::elapsedTime() - pause_start_sec); 4039 4040 // It is not yet to safe to tell the concurrent mark to 4041 // start as we have some optional output below. We don't want the 4042 // output from the concurrent mark thread interfering with this 4043 // logging output either. 4044 4045 _hrm.verify_optional(); 4046 verify_region_sets_optional(); 4047 4048 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats()); 4049 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4050 4051 print_heap_after_gc(); 4052 trace_heap_after_gc(_gc_tracer_stw); 4053 4054 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4055 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4056 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4057 // before any GC notifications are raised. 4058 g1mm()->update_sizes(); 4059 4060 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4061 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4062 _gc_timer_stw->register_gc_end(); 4063 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4064 } 4065 // It should now be safe to tell the concurrent mark thread to start 4066 // without its logging output interfering with the logging output 4067 // that came from the pause. 4068 4069 if (should_start_conc_mark) { 4070 // CAUTION: after the doConcurrentMark() call below, 4071 // the concurrent marking thread(s) could be running 4072 // concurrently with us. Make sure that anything after 4073 // this point does not assume that we are the only GC thread 4074 // running. Note: of course, the actual marking work will 4075 // not start until the safepoint itself is released in 4076 // SuspendibleThreadSet::desynchronize(). 4077 doConcurrentMark(); 4078 } 4079 4080 return true; 4081 } 4082 4083 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4084 _drain_in_progress = false; 4085 set_evac_failure_closure(cl); 4086 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4087 } 4088 4089 void G1CollectedHeap::finalize_for_evac_failure() { 4090 assert(_evac_failure_scan_stack != NULL && 4091 _evac_failure_scan_stack->length() == 0, 4092 "Postcondition"); 4093 assert(!_drain_in_progress, "Postcondition"); 4094 delete _evac_failure_scan_stack; 4095 _evac_failure_scan_stack = NULL; 4096 } 4097 4098 void G1CollectedHeap::remove_self_forwarding_pointers() { 4099 double remove_self_forwards_start = os::elapsedTime(); 4100 4101 set_par_threads(); 4102 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4103 workers()->run_task(&rsfp_task); 4104 set_par_threads(0); 4105 4106 // Now restore saved marks, if any. 4107 assert(_objs_with_preserved_marks.size() == 4108 _preserved_marks_of_objs.size(), "Both or none."); 4109 while (!_objs_with_preserved_marks.is_empty()) { 4110 oop obj = _objs_with_preserved_marks.pop(); 4111 markOop m = _preserved_marks_of_objs.pop(); 4112 obj->set_mark(m); 4113 } 4114 _objs_with_preserved_marks.clear(true); 4115 _preserved_marks_of_objs.clear(true); 4116 4117 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4118 } 4119 4120 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4121 _evac_failure_scan_stack->push(obj); 4122 } 4123 4124 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4125 assert(_evac_failure_scan_stack != NULL, "precondition"); 4126 4127 while (_evac_failure_scan_stack->length() > 0) { 4128 oop obj = _evac_failure_scan_stack->pop(); 4129 _evac_failure_closure->set_region(heap_region_containing(obj)); 4130 obj->oop_iterate_backwards(_evac_failure_closure); 4131 } 4132 } 4133 4134 oop 4135 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4136 oop old) { 4137 assert(obj_in_cs(old), 4138 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4139 (HeapWord*) old)); 4140 markOop m = old->mark(); 4141 oop forward_ptr = old->forward_to_atomic(old); 4142 if (forward_ptr == NULL) { 4143 // Forward-to-self succeeded. 4144 assert(_par_scan_state != NULL, "par scan state"); 4145 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4146 uint queue_num = _par_scan_state->queue_num(); 4147 4148 _evacuation_failed = true; 4149 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4150 if (_evac_failure_closure != cl) { 4151 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4152 assert(!_drain_in_progress, 4153 "Should only be true while someone holds the lock."); 4154 // Set the global evac-failure closure to the current thread's. 4155 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4156 set_evac_failure_closure(cl); 4157 // Now do the common part. 4158 handle_evacuation_failure_common(old, m); 4159 // Reset to NULL. 4160 set_evac_failure_closure(NULL); 4161 } else { 4162 // The lock is already held, and this is recursive. 4163 assert(_drain_in_progress, "This should only be the recursive case."); 4164 handle_evacuation_failure_common(old, m); 4165 } 4166 return old; 4167 } else { 4168 // Forward-to-self failed. Either someone else managed to allocate 4169 // space for this object (old != forward_ptr) or they beat us in 4170 // self-forwarding it (old == forward_ptr). 4171 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4172 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4173 "should not be in the CSet", 4174 (HeapWord*) old, (HeapWord*) forward_ptr)); 4175 return forward_ptr; 4176 } 4177 } 4178 4179 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4180 preserve_mark_if_necessary(old, m); 4181 4182 HeapRegion* r = heap_region_containing(old); 4183 if (!r->evacuation_failed()) { 4184 r->set_evacuation_failed(true); 4185 _hr_printer.evac_failure(r); 4186 } 4187 4188 push_on_evac_failure_scan_stack(old); 4189 4190 if (!_drain_in_progress) { 4191 // prevent recursion in copy_to_survivor_space() 4192 _drain_in_progress = true; 4193 drain_evac_failure_scan_stack(); 4194 _drain_in_progress = false; 4195 } 4196 } 4197 4198 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4199 assert(evacuation_failed(), "Oversaving!"); 4200 // We want to call the "for_promotion_failure" version only in the 4201 // case of a promotion failure. 4202 if (m->must_be_preserved_for_promotion_failure(obj)) { 4203 _objs_with_preserved_marks.push(obj); 4204 _preserved_marks_of_objs.push(m); 4205 } 4206 } 4207 4208 void G1ParCopyHelper::mark_object(oop obj) { 4209 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); 4210 4211 // We know that the object is not moving so it's safe to read its size. 4212 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4213 } 4214 4215 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4216 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4217 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4218 assert(from_obj != to_obj, "should not be self-forwarded"); 4219 4220 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); 4221 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); 4222 4223 // The object might be in the process of being copied by another 4224 // worker so we cannot trust that its to-space image is 4225 // well-formed. So we have to read its size from its from-space 4226 // image which we know should not be changing. 4227 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4228 } 4229 4230 template <class T> 4231 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4232 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4233 _scanned_klass->record_modified_oops(); 4234 } 4235 } 4236 4237 template <G1Barrier barrier, G1Mark do_mark_object> 4238 template <class T> 4239 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4240 T heap_oop = oopDesc::load_heap_oop(p); 4241 4242 if (oopDesc::is_null(heap_oop)) { 4243 return; 4244 } 4245 4246 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4247 4248 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4249 4250 const InCSetState state = _g1->in_cset_state(obj); 4251 if (state.is_in_cset()) { 4252 oop forwardee; 4253 markOop m = obj->mark(); 4254 if (m->is_marked()) { 4255 forwardee = (oop) m->decode_pointer(); 4256 } else { 4257 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m); 4258 } 4259 assert(forwardee != NULL, "forwardee should not be NULL"); 4260 oopDesc::encode_store_heap_oop(p, forwardee); 4261 if (do_mark_object != G1MarkNone && forwardee != obj) { 4262 // If the object is self-forwarded we don't need to explicitly 4263 // mark it, the evacuation failure protocol will do so. 4264 mark_forwarded_object(obj, forwardee); 4265 } 4266 4267 if (barrier == G1BarrierKlass) { 4268 do_klass_barrier(p, forwardee); 4269 } 4270 } else { 4271 if (state.is_humongous()) { 4272 _g1->set_humongous_is_live(obj); 4273 } 4274 // The object is not in collection set. If we're a root scanning 4275 // closure during an initial mark pause then attempt to mark the object. 4276 if (do_mark_object == G1MarkFromRoot) { 4277 mark_object(obj); 4278 } 4279 } 4280 4281 if (barrier == G1BarrierEvac) { 4282 _par_scan_state->update_rs(_from, p, _worker_id); 4283 } 4284 } 4285 4286 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p); 4287 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p); 4288 4289 class G1ParEvacuateFollowersClosure : public VoidClosure { 4290 protected: 4291 G1CollectedHeap* _g1h; 4292 G1ParScanThreadState* _par_scan_state; 4293 RefToScanQueueSet* _queues; 4294 ParallelTaskTerminator* _terminator; 4295 4296 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4297 RefToScanQueueSet* queues() { return _queues; } 4298 ParallelTaskTerminator* terminator() { return _terminator; } 4299 4300 public: 4301 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4302 G1ParScanThreadState* par_scan_state, 4303 RefToScanQueueSet* queues, 4304 ParallelTaskTerminator* terminator) 4305 : _g1h(g1h), _par_scan_state(par_scan_state), 4306 _queues(queues), _terminator(terminator) {} 4307 4308 void do_void(); 4309 4310 private: 4311 inline bool offer_termination(); 4312 }; 4313 4314 bool G1ParEvacuateFollowersClosure::offer_termination() { 4315 G1ParScanThreadState* const pss = par_scan_state(); 4316 pss->start_term_time(); 4317 const bool res = terminator()->offer_termination(); 4318 pss->end_term_time(); 4319 return res; 4320 } 4321 4322 void G1ParEvacuateFollowersClosure::do_void() { 4323 G1ParScanThreadState* const pss = par_scan_state(); 4324 pss->trim_queue(); 4325 do { 4326 pss->steal_and_trim_queue(queues()); 4327 } while (!offer_termination()); 4328 } 4329 4330 class G1KlassScanClosure : public KlassClosure { 4331 G1ParCopyHelper* _closure; 4332 bool _process_only_dirty; 4333 int _count; 4334 public: 4335 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4336 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4337 void do_klass(Klass* klass) { 4338 // If the klass has not been dirtied we know that there's 4339 // no references into the young gen and we can skip it. 4340 if (!_process_only_dirty || klass->has_modified_oops()) { 4341 // Clean the klass since we're going to scavenge all the metadata. 4342 klass->clear_modified_oops(); 4343 4344 // Tell the closure that this klass is the Klass to scavenge 4345 // and is the one to dirty if oops are left pointing into the young gen. 4346 _closure->set_scanned_klass(klass); 4347 4348 klass->oops_do(_closure); 4349 4350 _closure->set_scanned_klass(NULL); 4351 } 4352 _count++; 4353 } 4354 }; 4355 4356 class G1ParTask : public AbstractGangTask { 4357 protected: 4358 G1CollectedHeap* _g1h; 4359 RefToScanQueueSet *_queues; 4360 G1RootProcessor* _root_processor; 4361 ParallelTaskTerminator _terminator; 4362 uint _n_workers; 4363 4364 Mutex _stats_lock; 4365 Mutex* stats_lock() { return &_stats_lock; } 4366 4367 public: 4368 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor) 4369 : AbstractGangTask("G1 collection"), 4370 _g1h(g1h), 4371 _queues(task_queues), 4372 _root_processor(root_processor), 4373 _terminator(0, _queues), 4374 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4375 {} 4376 4377 RefToScanQueueSet* queues() { return _queues; } 4378 4379 RefToScanQueue *work_queue(int i) { 4380 return queues()->queue(i); 4381 } 4382 4383 ParallelTaskTerminator* terminator() { return &_terminator; } 4384 4385 virtual void set_for_termination(int active_workers) { 4386 _root_processor->set_num_workers(active_workers); 4387 terminator()->reset_for_reuse(active_workers); 4388 _n_workers = active_workers; 4389 } 4390 4391 // Helps out with CLD processing. 4392 // 4393 // During InitialMark we need to: 4394 // 1) Scavenge all CLDs for the young GC. 4395 // 2) Mark all objects directly reachable from strong CLDs. 4396 template <G1Mark do_mark_object> 4397 class G1CLDClosure : public CLDClosure { 4398 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure; 4399 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure; 4400 G1KlassScanClosure _klass_in_cld_closure; 4401 bool _claim; 4402 4403 public: 4404 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure, 4405 bool only_young, bool claim) 4406 : _oop_closure(oop_closure), 4407 _oop_in_klass_closure(oop_closure->g1(), 4408 oop_closure->pss(), 4409 oop_closure->rp()), 4410 _klass_in_cld_closure(&_oop_in_klass_closure, only_young), 4411 _claim(claim) { 4412 4413 } 4414 4415 void do_cld(ClassLoaderData* cld) { 4416 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim); 4417 } 4418 }; 4419 4420 void work(uint worker_id) { 4421 if (worker_id >= _n_workers) return; // no work needed this round 4422 4423 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime()); 4424 4425 { 4426 ResourceMark rm; 4427 HandleMark hm; 4428 4429 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4430 4431 G1ParScanThreadState pss(_g1h, worker_id, rp); 4432 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 4433 4434 pss.set_evac_failure_closure(&evac_failure_cl); 4435 4436 bool only_young = _g1h->g1_policy()->gcs_are_young(); 4437 4438 // Non-IM young GC. 4439 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp); 4440 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl, 4441 only_young, // Only process dirty klasses. 4442 false); // No need to claim CLDs. 4443 // IM young GC. 4444 // Strong roots closures. 4445 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp); 4446 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl, 4447 false, // Process all klasses. 4448 true); // Need to claim CLDs. 4449 // Weak roots closures. 4450 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp); 4451 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl, 4452 false, // Process all klasses. 4453 true); // Need to claim CLDs. 4454 4455 OopClosure* strong_root_cl; 4456 OopClosure* weak_root_cl; 4457 CLDClosure* strong_cld_cl; 4458 CLDClosure* weak_cld_cl; 4459 4460 bool trace_metadata = false; 4461 4462 if (_g1h->g1_policy()->during_initial_mark_pause()) { 4463 // We also need to mark copied objects. 4464 strong_root_cl = &scan_mark_root_cl; 4465 strong_cld_cl = &scan_mark_cld_cl; 4466 if (ClassUnloadingWithConcurrentMark) { 4467 weak_root_cl = &scan_mark_weak_root_cl; 4468 weak_cld_cl = &scan_mark_weak_cld_cl; 4469 trace_metadata = true; 4470 } else { 4471 weak_root_cl = &scan_mark_root_cl; 4472 weak_cld_cl = &scan_mark_cld_cl; 4473 } 4474 } else { 4475 strong_root_cl = &scan_only_root_cl; 4476 weak_root_cl = &scan_only_root_cl; 4477 strong_cld_cl = &scan_only_cld_cl; 4478 weak_cld_cl = &scan_only_cld_cl; 4479 } 4480 4481 pss.start_strong_roots(); 4482 4483 _root_processor->evacuate_roots(strong_root_cl, 4484 weak_root_cl, 4485 strong_cld_cl, 4486 weak_cld_cl, 4487 trace_metadata, 4488 worker_id); 4489 4490 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4491 _root_processor->scan_remembered_sets(&push_heap_rs_cl, 4492 weak_root_cl, 4493 worker_id); 4494 pss.end_strong_roots(); 4495 4496 { 4497 double start = os::elapsedTime(); 4498 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4499 evac.do_void(); 4500 double elapsed_sec = os::elapsedTime() - start; 4501 double term_sec = pss.term_time(); 4502 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 4503 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 4504 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts()); 4505 } 4506 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4507 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4508 4509 if (PrintTerminationStats) { 4510 MutexLocker x(stats_lock()); 4511 pss.print_termination_stats(worker_id); 4512 } 4513 4514 assert(pss.queue_is_empty(), "should be empty"); 4515 4516 // Close the inner scope so that the ResourceMark and HandleMark 4517 // destructors are executed here and are included as part of the 4518 // "GC Worker Time". 4519 } 4520 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 4521 } 4522 }; 4523 4524 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4525 private: 4526 BoolObjectClosure* _is_alive; 4527 int _initial_string_table_size; 4528 int _initial_symbol_table_size; 4529 4530 bool _process_strings; 4531 int _strings_processed; 4532 int _strings_removed; 4533 4534 bool _process_symbols; 4535 int _symbols_processed; 4536 int _symbols_removed; 4537 4538 public: 4539 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4540 AbstractGangTask("String/Symbol Unlinking"), 4541 _is_alive(is_alive), 4542 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4543 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4544 4545 _initial_string_table_size = StringTable::the_table()->table_size(); 4546 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4547 if (process_strings) { 4548 StringTable::clear_parallel_claimed_index(); 4549 } 4550 if (process_symbols) { 4551 SymbolTable::clear_parallel_claimed_index(); 4552 } 4553 } 4554 4555 ~G1StringSymbolTableUnlinkTask() { 4556 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4557 err_msg("claim value %d after unlink less than initial string table size %d", 4558 StringTable::parallel_claimed_index(), _initial_string_table_size)); 4559 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4560 err_msg("claim value %d after unlink less than initial symbol table size %d", 4561 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 4562 4563 if (G1TraceStringSymbolTableScrubbing) { 4564 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4565 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 4566 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 4567 strings_processed(), strings_removed(), 4568 symbols_processed(), symbols_removed()); 4569 } 4570 } 4571 4572 void work(uint worker_id) { 4573 int strings_processed = 0; 4574 int strings_removed = 0; 4575 int symbols_processed = 0; 4576 int symbols_removed = 0; 4577 if (_process_strings) { 4578 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4579 Atomic::add(strings_processed, &_strings_processed); 4580 Atomic::add(strings_removed, &_strings_removed); 4581 } 4582 if (_process_symbols) { 4583 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 4584 Atomic::add(symbols_processed, &_symbols_processed); 4585 Atomic::add(symbols_removed, &_symbols_removed); 4586 } 4587 } 4588 4589 size_t strings_processed() const { return (size_t)_strings_processed; } 4590 size_t strings_removed() const { return (size_t)_strings_removed; } 4591 4592 size_t symbols_processed() const { return (size_t)_symbols_processed; } 4593 size_t symbols_removed() const { return (size_t)_symbols_removed; } 4594 }; 4595 4596 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 4597 private: 4598 static Monitor* _lock; 4599 4600 BoolObjectClosure* const _is_alive; 4601 const bool _unloading_occurred; 4602 const uint _num_workers; 4603 4604 // Variables used to claim nmethods. 4605 nmethod* _first_nmethod; 4606 volatile nmethod* _claimed_nmethod; 4607 4608 // The list of nmethods that need to be processed by the second pass. 4609 volatile nmethod* _postponed_list; 4610 volatile uint _num_entered_barrier; 4611 4612 public: 4613 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 4614 _is_alive(is_alive), 4615 _unloading_occurred(unloading_occurred), 4616 _num_workers(num_workers), 4617 _first_nmethod(NULL), 4618 _claimed_nmethod(NULL), 4619 _postponed_list(NULL), 4620 _num_entered_barrier(0) 4621 { 4622 nmethod::increase_unloading_clock(); 4623 // Get first alive nmethod 4624 NMethodIterator iter = NMethodIterator(); 4625 if(iter.next_alive()) { 4626 _first_nmethod = iter.method(); 4627 } 4628 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 4629 } 4630 4631 ~G1CodeCacheUnloadingTask() { 4632 CodeCache::verify_clean_inline_caches(); 4633 4634 CodeCache::set_needs_cache_clean(false); 4635 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 4636 4637 CodeCache::verify_icholder_relocations(); 4638 } 4639 4640 private: 4641 void add_to_postponed_list(nmethod* nm) { 4642 nmethod* old; 4643 do { 4644 old = (nmethod*)_postponed_list; 4645 nm->set_unloading_next(old); 4646 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 4647 } 4648 4649 void clean_nmethod(nmethod* nm) { 4650 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 4651 4652 if (postponed) { 4653 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 4654 add_to_postponed_list(nm); 4655 } 4656 4657 // Mark that this thread has been cleaned/unloaded. 4658 // After this call, it will be safe to ask if this nmethod was unloaded or not. 4659 nm->set_unloading_clock(nmethod::global_unloading_clock()); 4660 } 4661 4662 void clean_nmethod_postponed(nmethod* nm) { 4663 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 4664 } 4665 4666 static const int MaxClaimNmethods = 16; 4667 4668 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 4669 nmethod* first; 4670 NMethodIterator last; 4671 4672 do { 4673 *num_claimed_nmethods = 0; 4674 4675 first = (nmethod*)_claimed_nmethod; 4676 last = NMethodIterator(first); 4677 4678 if (first != NULL) { 4679 4680 for (int i = 0; i < MaxClaimNmethods; i++) { 4681 if (!last.next_alive()) { 4682 break; 4683 } 4684 claimed_nmethods[i] = last.method(); 4685 (*num_claimed_nmethods)++; 4686 } 4687 } 4688 4689 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 4690 } 4691 4692 nmethod* claim_postponed_nmethod() { 4693 nmethod* claim; 4694 nmethod* next; 4695 4696 do { 4697 claim = (nmethod*)_postponed_list; 4698 if (claim == NULL) { 4699 return NULL; 4700 } 4701 4702 next = claim->unloading_next(); 4703 4704 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 4705 4706 return claim; 4707 } 4708 4709 public: 4710 // Mark that we're done with the first pass of nmethod cleaning. 4711 void barrier_mark(uint worker_id) { 4712 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4713 _num_entered_barrier++; 4714 if (_num_entered_barrier == _num_workers) { 4715 ml.notify_all(); 4716 } 4717 } 4718 4719 // See if we have to wait for the other workers to 4720 // finish their first-pass nmethod cleaning work. 4721 void barrier_wait(uint worker_id) { 4722 if (_num_entered_barrier < _num_workers) { 4723 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4724 while (_num_entered_barrier < _num_workers) { 4725 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 4726 } 4727 } 4728 } 4729 4730 // Cleaning and unloading of nmethods. Some work has to be postponed 4731 // to the second pass, when we know which nmethods survive. 4732 void work_first_pass(uint worker_id) { 4733 // The first nmethods is claimed by the first worker. 4734 if (worker_id == 0 && _first_nmethod != NULL) { 4735 clean_nmethod(_first_nmethod); 4736 _first_nmethod = NULL; 4737 } 4738 4739 int num_claimed_nmethods; 4740 nmethod* claimed_nmethods[MaxClaimNmethods]; 4741 4742 while (true) { 4743 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 4744 4745 if (num_claimed_nmethods == 0) { 4746 break; 4747 } 4748 4749 for (int i = 0; i < num_claimed_nmethods; i++) { 4750 clean_nmethod(claimed_nmethods[i]); 4751 } 4752 } 4753 } 4754 4755 void work_second_pass(uint worker_id) { 4756 nmethod* nm; 4757 // Take care of postponed nmethods. 4758 while ((nm = claim_postponed_nmethod()) != NULL) { 4759 clean_nmethod_postponed(nm); 4760 } 4761 } 4762 }; 4763 4764 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 4765 4766 class G1KlassCleaningTask : public StackObj { 4767 BoolObjectClosure* _is_alive; 4768 volatile jint _clean_klass_tree_claimed; 4769 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 4770 4771 public: 4772 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 4773 _is_alive(is_alive), 4774 _clean_klass_tree_claimed(0), 4775 _klass_iterator() { 4776 } 4777 4778 private: 4779 bool claim_clean_klass_tree_task() { 4780 if (_clean_klass_tree_claimed) { 4781 return false; 4782 } 4783 4784 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 4785 } 4786 4787 InstanceKlass* claim_next_klass() { 4788 Klass* klass; 4789 do { 4790 klass =_klass_iterator.next_klass(); 4791 } while (klass != NULL && !klass->oop_is_instance()); 4792 4793 return (InstanceKlass*)klass; 4794 } 4795 4796 public: 4797 4798 void clean_klass(InstanceKlass* ik) { 4799 ik->clean_implementors_list(_is_alive); 4800 ik->clean_method_data(_is_alive); 4801 4802 // G1 specific cleanup work that has 4803 // been moved here to be done in parallel. 4804 ik->clean_dependent_nmethods(); 4805 } 4806 4807 void work() { 4808 ResourceMark rm; 4809 4810 // One worker will clean the subklass/sibling klass tree. 4811 if (claim_clean_klass_tree_task()) { 4812 Klass::clean_subklass_tree(_is_alive); 4813 } 4814 4815 // All workers will help cleaning the classes, 4816 InstanceKlass* klass; 4817 while ((klass = claim_next_klass()) != NULL) { 4818 clean_klass(klass); 4819 } 4820 } 4821 }; 4822 4823 // To minimize the remark pause times, the tasks below are done in parallel. 4824 class G1ParallelCleaningTask : public AbstractGangTask { 4825 private: 4826 G1StringSymbolTableUnlinkTask _string_symbol_task; 4827 G1CodeCacheUnloadingTask _code_cache_task; 4828 G1KlassCleaningTask _klass_cleaning_task; 4829 4830 public: 4831 // The constructor is run in the VMThread. 4832 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 4833 AbstractGangTask("Parallel Cleaning"), 4834 _string_symbol_task(is_alive, process_strings, process_symbols), 4835 _code_cache_task(num_workers, is_alive, unloading_occurred), 4836 _klass_cleaning_task(is_alive) { 4837 } 4838 4839 // The parallel work done by all worker threads. 4840 void work(uint worker_id) { 4841 // Do first pass of code cache cleaning. 4842 _code_cache_task.work_first_pass(worker_id); 4843 4844 // Let the threads mark that the first pass is done. 4845 _code_cache_task.barrier_mark(worker_id); 4846 4847 // Clean the Strings and Symbols. 4848 _string_symbol_task.work(worker_id); 4849 4850 // Wait for all workers to finish the first code cache cleaning pass. 4851 _code_cache_task.barrier_wait(worker_id); 4852 4853 // Do the second code cache cleaning work, which realize on 4854 // the liveness information gathered during the first pass. 4855 _code_cache_task.work_second_pass(worker_id); 4856 4857 // Clean all klasses that were not unloaded. 4858 _klass_cleaning_task.work(); 4859 } 4860 }; 4861 4862 4863 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 4864 bool process_strings, 4865 bool process_symbols, 4866 bool class_unloading_occurred) { 4867 uint n_workers = workers()->active_workers(); 4868 4869 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 4870 n_workers, class_unloading_occurred); 4871 set_par_threads(n_workers); 4872 workers()->run_task(&g1_unlink_task); 4873 set_par_threads(0); 4874 } 4875 4876 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 4877 bool process_strings, bool process_symbols) { 4878 { 4879 uint n_workers = _g1h->workers()->active_workers(); 4880 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 4881 set_par_threads(n_workers); 4882 workers()->run_task(&g1_unlink_task); 4883 set_par_threads(0); 4884 } 4885 4886 if (G1StringDedup::is_enabled()) { 4887 G1StringDedup::unlink(is_alive); 4888 } 4889 } 4890 4891 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 4892 private: 4893 DirtyCardQueueSet* _queue; 4894 public: 4895 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 4896 4897 virtual void work(uint worker_id) { 4898 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4899 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 4900 4901 RedirtyLoggedCardTableEntryClosure cl; 4902 _queue->par_apply_closure_to_all_completed_buffers(&cl); 4903 4904 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed()); 4905 } 4906 }; 4907 4908 void G1CollectedHeap::redirty_logged_cards() { 4909 double redirty_logged_cards_start = os::elapsedTime(); 4910 4911 uint n_workers = _g1h->workers()->active_workers(); 4912 4913 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 4914 dirty_card_queue_set().reset_for_par_iteration(); 4915 set_par_threads(n_workers); 4916 workers()->run_task(&redirty_task); 4917 set_par_threads(0); 4918 4919 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 4920 dcq.merge_bufferlists(&dirty_card_queue_set()); 4921 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 4922 4923 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 4924 } 4925 4926 // Weak Reference Processing support 4927 4928 // An always "is_alive" closure that is used to preserve referents. 4929 // If the object is non-null then it's alive. Used in the preservation 4930 // of referent objects that are pointed to by reference objects 4931 // discovered by the CM ref processor. 4932 class G1AlwaysAliveClosure: public BoolObjectClosure { 4933 G1CollectedHeap* _g1; 4934 public: 4935 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4936 bool do_object_b(oop p) { 4937 if (p != NULL) { 4938 return true; 4939 } 4940 return false; 4941 } 4942 }; 4943 4944 bool G1STWIsAliveClosure::do_object_b(oop p) { 4945 // An object is reachable if it is outside the collection set, 4946 // or is inside and copied. 4947 return !_g1->obj_in_cs(p) || p->is_forwarded(); 4948 } 4949 4950 // Non Copying Keep Alive closure 4951 class G1KeepAliveClosure: public OopClosure { 4952 G1CollectedHeap* _g1; 4953 public: 4954 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4955 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 4956 void do_oop(oop* p) { 4957 oop obj = *p; 4958 assert(obj != NULL, "the caller should have filtered out NULL values"); 4959 4960 const InCSetState cset_state = _g1->in_cset_state(obj); 4961 if (!cset_state.is_in_cset_or_humongous()) { 4962 return; 4963 } 4964 if (cset_state.is_in_cset()) { 4965 assert( obj->is_forwarded(), "invariant" ); 4966 *p = obj->forwardee(); 4967 } else { 4968 assert(!obj->is_forwarded(), "invariant" ); 4969 assert(cset_state.is_humongous(), 4970 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value())); 4971 _g1->set_humongous_is_live(obj); 4972 } 4973 } 4974 }; 4975 4976 // Copying Keep Alive closure - can be called from both 4977 // serial and parallel code as long as different worker 4978 // threads utilize different G1ParScanThreadState instances 4979 // and different queues. 4980 4981 class G1CopyingKeepAliveClosure: public OopClosure { 4982 G1CollectedHeap* _g1h; 4983 OopClosure* _copy_non_heap_obj_cl; 4984 G1ParScanThreadState* _par_scan_state; 4985 4986 public: 4987 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 4988 OopClosure* non_heap_obj_cl, 4989 G1ParScanThreadState* pss): 4990 _g1h(g1h), 4991 _copy_non_heap_obj_cl(non_heap_obj_cl), 4992 _par_scan_state(pss) 4993 {} 4994 4995 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 4996 virtual void do_oop( oop* p) { do_oop_work(p); } 4997 4998 template <class T> void do_oop_work(T* p) { 4999 oop obj = oopDesc::load_decode_heap_oop(p); 5000 5001 if (_g1h->is_in_cset_or_humongous(obj)) { 5002 // If the referent object has been forwarded (either copied 5003 // to a new location or to itself in the event of an 5004 // evacuation failure) then we need to update the reference 5005 // field and, if both reference and referent are in the G1 5006 // heap, update the RSet for the referent. 5007 // 5008 // If the referent has not been forwarded then we have to keep 5009 // it alive by policy. Therefore we have copy the referent. 5010 // 5011 // If the reference field is in the G1 heap then we can push 5012 // on the PSS queue. When the queue is drained (after each 5013 // phase of reference processing) the object and it's followers 5014 // will be copied, the reference field set to point to the 5015 // new location, and the RSet updated. Otherwise we need to 5016 // use the the non-heap or metadata closures directly to copy 5017 // the referent object and update the pointer, while avoiding 5018 // updating the RSet. 5019 5020 if (_g1h->is_in_g1_reserved(p)) { 5021 _par_scan_state->push_on_queue(p); 5022 } else { 5023 assert(!Metaspace::contains((const void*)p), 5024 err_msg("Unexpectedly found a pointer from metadata: " 5025 PTR_FORMAT, p)); 5026 _copy_non_heap_obj_cl->do_oop(p); 5027 } 5028 } 5029 } 5030 }; 5031 5032 // Serial drain queue closure. Called as the 'complete_gc' 5033 // closure for each discovered list in some of the 5034 // reference processing phases. 5035 5036 class G1STWDrainQueueClosure: public VoidClosure { 5037 protected: 5038 G1CollectedHeap* _g1h; 5039 G1ParScanThreadState* _par_scan_state; 5040 5041 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5042 5043 public: 5044 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5045 _g1h(g1h), 5046 _par_scan_state(pss) 5047 { } 5048 5049 void do_void() { 5050 G1ParScanThreadState* const pss = par_scan_state(); 5051 pss->trim_queue(); 5052 } 5053 }; 5054 5055 // Parallel Reference Processing closures 5056 5057 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5058 // processing during G1 evacuation pauses. 5059 5060 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5061 private: 5062 G1CollectedHeap* _g1h; 5063 RefToScanQueueSet* _queues; 5064 FlexibleWorkGang* _workers; 5065 int _active_workers; 5066 5067 public: 5068 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5069 FlexibleWorkGang* workers, 5070 RefToScanQueueSet *task_queues, 5071 int n_workers) : 5072 _g1h(g1h), 5073 _queues(task_queues), 5074 _workers(workers), 5075 _active_workers(n_workers) 5076 { 5077 assert(n_workers > 0, "shouldn't call this otherwise"); 5078 } 5079 5080 // Executes the given task using concurrent marking worker threads. 5081 virtual void execute(ProcessTask& task); 5082 virtual void execute(EnqueueTask& task); 5083 }; 5084 5085 // Gang task for possibly parallel reference processing 5086 5087 class G1STWRefProcTaskProxy: public AbstractGangTask { 5088 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5089 ProcessTask& _proc_task; 5090 G1CollectedHeap* _g1h; 5091 RefToScanQueueSet *_task_queues; 5092 ParallelTaskTerminator* _terminator; 5093 5094 public: 5095 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5096 G1CollectedHeap* g1h, 5097 RefToScanQueueSet *task_queues, 5098 ParallelTaskTerminator* terminator) : 5099 AbstractGangTask("Process reference objects in parallel"), 5100 _proc_task(proc_task), 5101 _g1h(g1h), 5102 _task_queues(task_queues), 5103 _terminator(terminator) 5104 {} 5105 5106 virtual void work(uint worker_id) { 5107 // The reference processing task executed by a single worker. 5108 ResourceMark rm; 5109 HandleMark hm; 5110 5111 G1STWIsAliveClosure is_alive(_g1h); 5112 5113 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5114 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5115 5116 pss.set_evac_failure_closure(&evac_failure_cl); 5117 5118 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5119 5120 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5121 5122 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5123 5124 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5125 // We also need to mark copied objects. 5126 copy_non_heap_cl = ©_mark_non_heap_cl; 5127 } 5128 5129 // Keep alive closure. 5130 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5131 5132 // Complete GC closure 5133 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5134 5135 // Call the reference processing task's work routine. 5136 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5137 5138 // Note we cannot assert that the refs array is empty here as not all 5139 // of the processing tasks (specifically phase2 - pp2_work) execute 5140 // the complete_gc closure (which ordinarily would drain the queue) so 5141 // the queue may not be empty. 5142 } 5143 }; 5144 5145 // Driver routine for parallel reference processing. 5146 // Creates an instance of the ref processing gang 5147 // task and has the worker threads execute it. 5148 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5149 assert(_workers != NULL, "Need parallel worker threads."); 5150 5151 ParallelTaskTerminator terminator(_active_workers, _queues); 5152 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5153 5154 _g1h->set_par_threads(_active_workers); 5155 _workers->run_task(&proc_task_proxy); 5156 _g1h->set_par_threads(0); 5157 } 5158 5159 // Gang task for parallel reference enqueueing. 5160 5161 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5162 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5163 EnqueueTask& _enq_task; 5164 5165 public: 5166 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5167 AbstractGangTask("Enqueue reference objects in parallel"), 5168 _enq_task(enq_task) 5169 { } 5170 5171 virtual void work(uint worker_id) { 5172 _enq_task.work(worker_id); 5173 } 5174 }; 5175 5176 // Driver routine for parallel reference enqueueing. 5177 // Creates an instance of the ref enqueueing gang 5178 // task and has the worker threads execute it. 5179 5180 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5181 assert(_workers != NULL, "Need parallel worker threads."); 5182 5183 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5184 5185 _g1h->set_par_threads(_active_workers); 5186 _workers->run_task(&enq_task_proxy); 5187 _g1h->set_par_threads(0); 5188 } 5189 5190 // End of weak reference support closures 5191 5192 // Abstract task used to preserve (i.e. copy) any referent objects 5193 // that are in the collection set and are pointed to by reference 5194 // objects discovered by the CM ref processor. 5195 5196 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5197 protected: 5198 G1CollectedHeap* _g1h; 5199 RefToScanQueueSet *_queues; 5200 ParallelTaskTerminator _terminator; 5201 uint _n_workers; 5202 5203 public: 5204 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5205 AbstractGangTask("ParPreserveCMReferents"), 5206 _g1h(g1h), 5207 _queues(task_queues), 5208 _terminator(workers, _queues), 5209 _n_workers(workers) 5210 { } 5211 5212 void work(uint worker_id) { 5213 ResourceMark rm; 5214 HandleMark hm; 5215 5216 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5217 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5218 5219 pss.set_evac_failure_closure(&evac_failure_cl); 5220 5221 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5222 5223 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5224 5225 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5226 5227 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5228 5229 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5230 // We also need to mark copied objects. 5231 copy_non_heap_cl = ©_mark_non_heap_cl; 5232 } 5233 5234 // Is alive closure 5235 G1AlwaysAliveClosure always_alive(_g1h); 5236 5237 // Copying keep alive closure. Applied to referent objects that need 5238 // to be copied. 5239 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5240 5241 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5242 5243 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5244 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5245 5246 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5247 // So this must be true - but assert just in case someone decides to 5248 // change the worker ids. 5249 assert(worker_id < limit, "sanity"); 5250 assert(!rp->discovery_is_atomic(), "check this code"); 5251 5252 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5253 for (uint idx = worker_id; idx < limit; idx += stride) { 5254 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5255 5256 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5257 while (iter.has_next()) { 5258 // Since discovery is not atomic for the CM ref processor, we 5259 // can see some null referent objects. 5260 iter.load_ptrs(DEBUG_ONLY(true)); 5261 oop ref = iter.obj(); 5262 5263 // This will filter nulls. 5264 if (iter.is_referent_alive()) { 5265 iter.make_referent_alive(); 5266 } 5267 iter.move_to_next(); 5268 } 5269 } 5270 5271 // Drain the queue - which may cause stealing 5272 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5273 drain_queue.do_void(); 5274 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5275 assert(pss.queue_is_empty(), "should be"); 5276 } 5277 }; 5278 5279 // Weak Reference processing during an evacuation pause (part 1). 5280 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5281 double ref_proc_start = os::elapsedTime(); 5282 5283 ReferenceProcessor* rp = _ref_processor_stw; 5284 assert(rp->discovery_enabled(), "should have been enabled"); 5285 5286 // Any reference objects, in the collection set, that were 'discovered' 5287 // by the CM ref processor should have already been copied (either by 5288 // applying the external root copy closure to the discovered lists, or 5289 // by following an RSet entry). 5290 // 5291 // But some of the referents, that are in the collection set, that these 5292 // reference objects point to may not have been copied: the STW ref 5293 // processor would have seen that the reference object had already 5294 // been 'discovered' and would have skipped discovering the reference, 5295 // but would not have treated the reference object as a regular oop. 5296 // As a result the copy closure would not have been applied to the 5297 // referent object. 5298 // 5299 // We need to explicitly copy these referent objects - the references 5300 // will be processed at the end of remarking. 5301 // 5302 // We also need to do this copying before we process the reference 5303 // objects discovered by the STW ref processor in case one of these 5304 // referents points to another object which is also referenced by an 5305 // object discovered by the STW ref processor. 5306 5307 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers"); 5308 5309 set_par_threads(no_of_gc_workers); 5310 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5311 no_of_gc_workers, 5312 _task_queues); 5313 5314 workers()->run_task(&keep_cm_referents); 5315 5316 set_par_threads(0); 5317 5318 // Closure to test whether a referent is alive. 5319 G1STWIsAliveClosure is_alive(this); 5320 5321 // Even when parallel reference processing is enabled, the processing 5322 // of JNI refs is serial and performed serially by the current thread 5323 // rather than by a worker. The following PSS will be used for processing 5324 // JNI refs. 5325 5326 // Use only a single queue for this PSS. 5327 G1ParScanThreadState pss(this, 0, NULL); 5328 5329 // We do not embed a reference processor in the copying/scanning 5330 // closures while we're actually processing the discovered 5331 // reference objects. 5332 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5333 5334 pss.set_evac_failure_closure(&evac_failure_cl); 5335 5336 assert(pss.queue_is_empty(), "pre-condition"); 5337 5338 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5339 5340 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5341 5342 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5343 5344 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5345 // We also need to mark copied objects. 5346 copy_non_heap_cl = ©_mark_non_heap_cl; 5347 } 5348 5349 // Keep alive closure. 5350 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss); 5351 5352 // Serial Complete GC closure 5353 G1STWDrainQueueClosure drain_queue(this, &pss); 5354 5355 // Setup the soft refs policy... 5356 rp->setup_policy(false); 5357 5358 ReferenceProcessorStats stats; 5359 if (!rp->processing_is_mt()) { 5360 // Serial reference processing... 5361 stats = rp->process_discovered_references(&is_alive, 5362 &keep_alive, 5363 &drain_queue, 5364 NULL, 5365 _gc_timer_stw, 5366 _gc_tracer_stw->gc_id()); 5367 } else { 5368 // Parallel reference processing 5369 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5370 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5371 5372 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5373 stats = rp->process_discovered_references(&is_alive, 5374 &keep_alive, 5375 &drain_queue, 5376 &par_task_executor, 5377 _gc_timer_stw, 5378 _gc_tracer_stw->gc_id()); 5379 } 5380 5381 _gc_tracer_stw->report_gc_reference_stats(stats); 5382 5383 // We have completed copying any necessary live referent objects. 5384 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5385 5386 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5387 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5388 } 5389 5390 // Weak Reference processing during an evacuation pause (part 2). 5391 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5392 double ref_enq_start = os::elapsedTime(); 5393 5394 ReferenceProcessor* rp = _ref_processor_stw; 5395 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5396 5397 // Now enqueue any remaining on the discovered lists on to 5398 // the pending list. 5399 if (!rp->processing_is_mt()) { 5400 // Serial reference processing... 5401 rp->enqueue_discovered_references(); 5402 } else { 5403 // Parallel reference enqueueing 5404 5405 assert(no_of_gc_workers == workers()->active_workers(), 5406 "Need to reset active workers"); 5407 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5408 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5409 5410 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5411 rp->enqueue_discovered_references(&par_task_executor); 5412 } 5413 5414 rp->verify_no_references_recorded(); 5415 assert(!rp->discovery_enabled(), "should have been disabled"); 5416 5417 // FIXME 5418 // CM's reference processing also cleans up the string and symbol tables. 5419 // Should we do that here also? We could, but it is a serial operation 5420 // and could significantly increase the pause time. 5421 5422 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5423 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5424 } 5425 5426 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5427 _expand_heap_after_alloc_failure = true; 5428 _evacuation_failed = false; 5429 5430 // Should G1EvacuationFailureALot be in effect for this GC? 5431 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5432 5433 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5434 5435 // Disable the hot card cache. 5436 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5437 hot_card_cache->reset_hot_cache_claimed_index(); 5438 hot_card_cache->set_use_cache(false); 5439 5440 uint n_workers; 5441 n_workers = 5442 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 5443 workers()->active_workers(), 5444 Threads::number_of_non_daemon_threads()); 5445 assert(UseDynamicNumberOfGCThreads || 5446 n_workers == workers()->total_workers(), 5447 "If not dynamic should be using all the workers"); 5448 workers()->set_active_workers(n_workers); 5449 set_par_threads(n_workers); 5450 5451 5452 init_for_evac_failure(NULL); 5453 5454 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5455 double start_par_time_sec = os::elapsedTime(); 5456 double end_par_time_sec; 5457 5458 { 5459 G1RootProcessor root_processor(this); 5460 G1ParTask g1_par_task(this, _task_queues, &root_processor); 5461 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5462 if (g1_policy()->during_initial_mark_pause()) { 5463 ClassLoaderDataGraph::clear_claimed_marks(); 5464 } 5465 5466 // The individual threads will set their evac-failure closures. 5467 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr(); 5468 // These tasks use ShareHeap::_process_strong_tasks 5469 assert(UseDynamicNumberOfGCThreads || 5470 workers()->active_workers() == workers()->total_workers(), 5471 "If not dynamic should be using all the workers"); 5472 workers()->run_task(&g1_par_task); 5473 end_par_time_sec = os::elapsedTime(); 5474 5475 // Closing the inner scope will execute the destructor 5476 // for the G1RootProcessor object. We record the current 5477 // elapsed time before closing the scope so that time 5478 // taken for the destructor is NOT included in the 5479 // reported parallel time. 5480 } 5481 5482 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 5483 5484 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5485 phase_times->record_par_time(par_time_ms); 5486 5487 double code_root_fixup_time_ms = 5488 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5489 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 5490 5491 set_par_threads(0); 5492 5493 // Process any discovered reference objects - we have 5494 // to do this _before_ we retire the GC alloc regions 5495 // as we may have to copy some 'reachable' referent 5496 // objects (and their reachable sub-graphs) that were 5497 // not copied during the pause. 5498 process_discovered_references(n_workers); 5499 5500 if (G1StringDedup::is_enabled()) { 5501 double fixup_start = os::elapsedTime(); 5502 5503 G1STWIsAliveClosure is_alive(this); 5504 G1KeepAliveClosure keep_alive(this); 5505 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times); 5506 5507 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 5508 phase_times->record_string_dedup_fixup_time(fixup_time_ms); 5509 } 5510 5511 _allocator->release_gc_alloc_regions(n_workers, evacuation_info); 5512 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5513 5514 // Reset and re-enable the hot card cache. 5515 // Note the counts for the cards in the regions in the 5516 // collection set are reset when the collection set is freed. 5517 hot_card_cache->reset_hot_cache(); 5518 hot_card_cache->set_use_cache(true); 5519 5520 purge_code_root_memory(); 5521 5522 finalize_for_evac_failure(); 5523 5524 if (evacuation_failed()) { 5525 remove_self_forwarding_pointers(); 5526 5527 // Reset the G1EvacuationFailureALot counters and flags 5528 // Note: the values are reset only when an actual 5529 // evacuation failure occurs. 5530 NOT_PRODUCT(reset_evacuation_should_fail();) 5531 } 5532 5533 // Enqueue any remaining references remaining on the STW 5534 // reference processor's discovered lists. We need to do 5535 // this after the card table is cleaned (and verified) as 5536 // the act of enqueueing entries on to the pending list 5537 // will log these updates (and dirty their associated 5538 // cards). We need these updates logged to update any 5539 // RSets. 5540 enqueue_discovered_references(n_workers); 5541 5542 redirty_logged_cards(); 5543 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5544 } 5545 5546 void G1CollectedHeap::free_region(HeapRegion* hr, 5547 FreeRegionList* free_list, 5548 bool par, 5549 bool locked) { 5550 assert(!hr->is_free(), "the region should not be free"); 5551 assert(!hr->is_empty(), "the region should not be empty"); 5552 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 5553 assert(free_list != NULL, "pre-condition"); 5554 5555 if (G1VerifyBitmaps) { 5556 MemRegion mr(hr->bottom(), hr->end()); 5557 concurrent_mark()->clearRangePrevBitmap(mr); 5558 } 5559 5560 // Clear the card counts for this region. 5561 // Note: we only need to do this if the region is not young 5562 // (since we don't refine cards in young regions). 5563 if (!hr->is_young()) { 5564 _cg1r->hot_card_cache()->reset_card_counts(hr); 5565 } 5566 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5567 free_list->add_ordered(hr); 5568 } 5569 5570 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5571 FreeRegionList* free_list, 5572 bool par) { 5573 assert(hr->is_starts_humongous(), "this is only for starts humongous regions"); 5574 assert(free_list != NULL, "pre-condition"); 5575 5576 size_t hr_capacity = hr->capacity(); 5577 // We need to read this before we make the region non-humongous, 5578 // otherwise the information will be gone. 5579 uint last_index = hr->last_hc_index(); 5580 hr->clear_humongous(); 5581 free_region(hr, free_list, par); 5582 5583 uint i = hr->hrm_index() + 1; 5584 while (i < last_index) { 5585 HeapRegion* curr_hr = region_at(i); 5586 assert(curr_hr->is_continues_humongous(), "invariant"); 5587 curr_hr->clear_humongous(); 5588 free_region(curr_hr, free_list, par); 5589 i += 1; 5590 } 5591 } 5592 5593 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 5594 const HeapRegionSetCount& humongous_regions_removed) { 5595 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5596 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5597 _old_set.bulk_remove(old_regions_removed); 5598 _humongous_set.bulk_remove(humongous_regions_removed); 5599 } 5600 5601 } 5602 5603 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 5604 assert(list != NULL, "list can't be null"); 5605 if (!list->is_empty()) { 5606 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5607 _hrm.insert_list_into_free_list(list); 5608 } 5609 } 5610 5611 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 5612 _allocator->decrease_used(bytes); 5613 } 5614 5615 class G1ParCleanupCTTask : public AbstractGangTask { 5616 G1SATBCardTableModRefBS* _ct_bs; 5617 G1CollectedHeap* _g1h; 5618 HeapRegion* volatile _su_head; 5619 public: 5620 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 5621 G1CollectedHeap* g1h) : 5622 AbstractGangTask("G1 Par Cleanup CT Task"), 5623 _ct_bs(ct_bs), _g1h(g1h) { } 5624 5625 void work(uint worker_id) { 5626 HeapRegion* r; 5627 while (r = _g1h->pop_dirty_cards_region()) { 5628 clear_cards(r); 5629 } 5630 } 5631 5632 void clear_cards(HeapRegion* r) { 5633 // Cards of the survivors should have already been dirtied. 5634 if (!r->is_survivor()) { 5635 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5636 } 5637 } 5638 }; 5639 5640 #ifndef PRODUCT 5641 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5642 G1CollectedHeap* _g1h; 5643 G1SATBCardTableModRefBS* _ct_bs; 5644 public: 5645 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 5646 : _g1h(g1h), _ct_bs(ct_bs) { } 5647 virtual bool doHeapRegion(HeapRegion* r) { 5648 if (r->is_survivor()) { 5649 _g1h->verify_dirty_region(r); 5650 } else { 5651 _g1h->verify_not_dirty_region(r); 5652 } 5653 return false; 5654 } 5655 }; 5656 5657 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5658 // All of the region should be clean. 5659 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5660 MemRegion mr(hr->bottom(), hr->end()); 5661 ct_bs->verify_not_dirty_region(mr); 5662 } 5663 5664 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5665 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5666 // dirty allocated blocks as they allocate them. The thread that 5667 // retires each region and replaces it with a new one will do a 5668 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5669 // not dirty that area (one less thing to have to do while holding 5670 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5671 // is dirty. 5672 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5673 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5674 if (hr->is_young()) { 5675 ct_bs->verify_g1_young_region(mr); 5676 } else { 5677 ct_bs->verify_dirty_region(mr); 5678 } 5679 } 5680 5681 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5682 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5683 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5684 verify_dirty_region(hr); 5685 } 5686 } 5687 5688 void G1CollectedHeap::verify_dirty_young_regions() { 5689 verify_dirty_young_list(_young_list->first_region()); 5690 } 5691 5692 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 5693 HeapWord* tams, HeapWord* end) { 5694 guarantee(tams <= end, 5695 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end)); 5696 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 5697 if (result < end) { 5698 gclog_or_tty->cr(); 5699 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT, 5700 bitmap_name, result); 5701 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT, 5702 bitmap_name, tams, end); 5703 return false; 5704 } 5705 return true; 5706 } 5707 5708 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 5709 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 5710 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 5711 5712 HeapWord* bottom = hr->bottom(); 5713 HeapWord* ptams = hr->prev_top_at_mark_start(); 5714 HeapWord* ntams = hr->next_top_at_mark_start(); 5715 HeapWord* end = hr->end(); 5716 5717 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 5718 5719 bool res_n = true; 5720 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 5721 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 5722 // if we happen to be in that state. 5723 if (mark_in_progress() || !_cmThread->in_progress()) { 5724 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 5725 } 5726 if (!res_p || !res_n) { 5727 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT, 5728 HR_FORMAT_PARAMS(hr)); 5729 gclog_or_tty->print_cr("#### Caller: %s", caller); 5730 return false; 5731 } 5732 return true; 5733 } 5734 5735 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 5736 if (!G1VerifyBitmaps) return; 5737 5738 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 5739 } 5740 5741 class G1VerifyBitmapClosure : public HeapRegionClosure { 5742 private: 5743 const char* _caller; 5744 G1CollectedHeap* _g1h; 5745 bool _failures; 5746 5747 public: 5748 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 5749 _caller(caller), _g1h(g1h), _failures(false) { } 5750 5751 bool failures() { return _failures; } 5752 5753 virtual bool doHeapRegion(HeapRegion* hr) { 5754 if (hr->is_continues_humongous()) return false; 5755 5756 bool result = _g1h->verify_bitmaps(_caller, hr); 5757 if (!result) { 5758 _failures = true; 5759 } 5760 return false; 5761 } 5762 }; 5763 5764 void G1CollectedHeap::check_bitmaps(const char* caller) { 5765 if (!G1VerifyBitmaps) return; 5766 5767 G1VerifyBitmapClosure cl(caller, this); 5768 heap_region_iterate(&cl); 5769 guarantee(!cl.failures(), "bitmap verification"); 5770 } 5771 5772 class G1CheckCSetFastTableClosure : public HeapRegionClosure { 5773 private: 5774 bool _failures; 5775 public: 5776 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { } 5777 5778 virtual bool doHeapRegion(HeapRegion* hr) { 5779 uint i = hr->hrm_index(); 5780 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i); 5781 if (hr->is_humongous()) { 5782 if (hr->in_collection_set()) { 5783 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i); 5784 _failures = true; 5785 return true; 5786 } 5787 if (cset_state.is_in_cset()) { 5788 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i); 5789 _failures = true; 5790 return true; 5791 } 5792 if (hr->is_continues_humongous() && cset_state.is_humongous()) { 5793 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i); 5794 _failures = true; 5795 return true; 5796 } 5797 } else { 5798 if (cset_state.is_humongous()) { 5799 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i); 5800 _failures = true; 5801 return true; 5802 } 5803 if (hr->in_collection_set() != cset_state.is_in_cset()) { 5804 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u", 5805 hr->in_collection_set(), cset_state.value(), i); 5806 _failures = true; 5807 return true; 5808 } 5809 if (cset_state.is_in_cset()) { 5810 if (hr->is_young() != (cset_state.is_young())) { 5811 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u", 5812 hr->is_young(), cset_state.value(), i); 5813 _failures = true; 5814 return true; 5815 } 5816 if (hr->is_old() != (cset_state.is_old())) { 5817 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u", 5818 hr->is_old(), cset_state.value(), i); 5819 _failures = true; 5820 return true; 5821 } 5822 } 5823 } 5824 return false; 5825 } 5826 5827 bool failures() const { return _failures; } 5828 }; 5829 5830 bool G1CollectedHeap::check_cset_fast_test() { 5831 G1CheckCSetFastTableClosure cl; 5832 _hrm.iterate(&cl); 5833 return !cl.failures(); 5834 } 5835 #endif // PRODUCT 5836 5837 void G1CollectedHeap::cleanUpCardTable() { 5838 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5839 double start = os::elapsedTime(); 5840 5841 { 5842 // Iterate over the dirty cards region list. 5843 G1ParCleanupCTTask cleanup_task(ct_bs, this); 5844 5845 set_par_threads(); 5846 workers()->run_task(&cleanup_task); 5847 set_par_threads(0); 5848 #ifndef PRODUCT 5849 if (G1VerifyCTCleanup || VerifyAfterGC) { 5850 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 5851 heap_region_iterate(&cleanup_verifier); 5852 } 5853 #endif 5854 } 5855 5856 double elapsed = os::elapsedTime() - start; 5857 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 5858 } 5859 5860 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 5861 size_t pre_used = 0; 5862 FreeRegionList local_free_list("Local List for CSet Freeing"); 5863 5864 double young_time_ms = 0.0; 5865 double non_young_time_ms = 0.0; 5866 5867 // Since the collection set is a superset of the the young list, 5868 // all we need to do to clear the young list is clear its 5869 // head and length, and unlink any young regions in the code below 5870 _young_list->clear(); 5871 5872 G1CollectorPolicy* policy = g1_policy(); 5873 5874 double start_sec = os::elapsedTime(); 5875 bool non_young = true; 5876 5877 HeapRegion* cur = cs_head; 5878 int age_bound = -1; 5879 size_t rs_lengths = 0; 5880 5881 while (cur != NULL) { 5882 assert(!is_on_master_free_list(cur), "sanity"); 5883 if (non_young) { 5884 if (cur->is_young()) { 5885 double end_sec = os::elapsedTime(); 5886 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5887 non_young_time_ms += elapsed_ms; 5888 5889 start_sec = os::elapsedTime(); 5890 non_young = false; 5891 } 5892 } else { 5893 if (!cur->is_young()) { 5894 double end_sec = os::elapsedTime(); 5895 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5896 young_time_ms += elapsed_ms; 5897 5898 start_sec = os::elapsedTime(); 5899 non_young = true; 5900 } 5901 } 5902 5903 rs_lengths += cur->rem_set()->occupied_locked(); 5904 5905 HeapRegion* next = cur->next_in_collection_set(); 5906 assert(cur->in_collection_set(), "bad CS"); 5907 cur->set_next_in_collection_set(NULL); 5908 clear_in_cset(cur); 5909 5910 if (cur->is_young()) { 5911 int index = cur->young_index_in_cset(); 5912 assert(index != -1, "invariant"); 5913 assert((uint) index < policy->young_cset_region_length(), "invariant"); 5914 size_t words_survived = _surviving_young_words[index]; 5915 cur->record_surv_words_in_group(words_survived); 5916 5917 // At this point the we have 'popped' cur from the collection set 5918 // (linked via next_in_collection_set()) but it is still in the 5919 // young list (linked via next_young_region()). Clear the 5920 // _next_young_region field. 5921 cur->set_next_young_region(NULL); 5922 } else { 5923 int index = cur->young_index_in_cset(); 5924 assert(index == -1, "invariant"); 5925 } 5926 5927 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 5928 (!cur->is_young() && cur->young_index_in_cset() == -1), 5929 "invariant" ); 5930 5931 if (!cur->evacuation_failed()) { 5932 MemRegion used_mr = cur->used_region(); 5933 5934 // And the region is empty. 5935 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 5936 pre_used += cur->used(); 5937 free_region(cur, &local_free_list, false /* par */, true /* locked */); 5938 } else { 5939 cur->uninstall_surv_rate_group(); 5940 if (cur->is_young()) { 5941 cur->set_young_index_in_cset(-1); 5942 } 5943 cur->set_evacuation_failed(false); 5944 // The region is now considered to be old. 5945 cur->set_old(); 5946 _old_set.add(cur); 5947 evacuation_info.increment_collectionset_used_after(cur->used()); 5948 } 5949 cur = next; 5950 } 5951 5952 evacuation_info.set_regions_freed(local_free_list.length()); 5953 policy->record_max_rs_lengths(rs_lengths); 5954 policy->cset_regions_freed(); 5955 5956 double end_sec = os::elapsedTime(); 5957 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5958 5959 if (non_young) { 5960 non_young_time_ms += elapsed_ms; 5961 } else { 5962 young_time_ms += elapsed_ms; 5963 } 5964 5965 prepend_to_freelist(&local_free_list); 5966 decrement_summary_bytes(pre_used); 5967 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 5968 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 5969 } 5970 5971 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 5972 private: 5973 FreeRegionList* _free_region_list; 5974 HeapRegionSet* _proxy_set; 5975 HeapRegionSetCount _humongous_regions_removed; 5976 size_t _freed_bytes; 5977 public: 5978 5979 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 5980 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 5981 } 5982 5983 virtual bool doHeapRegion(HeapRegion* r) { 5984 if (!r->is_starts_humongous()) { 5985 return false; 5986 } 5987 5988 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 5989 5990 oop obj = (oop)r->bottom(); 5991 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 5992 5993 // The following checks whether the humongous object is live are sufficient. 5994 // The main additional check (in addition to having a reference from the roots 5995 // or the young gen) is whether the humongous object has a remembered set entry. 5996 // 5997 // A humongous object cannot be live if there is no remembered set for it 5998 // because: 5999 // - there can be no references from within humongous starts regions referencing 6000 // the object because we never allocate other objects into them. 6001 // (I.e. there are no intra-region references that may be missed by the 6002 // remembered set) 6003 // - as soon there is a remembered set entry to the humongous starts region 6004 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 6005 // until the end of a concurrent mark. 6006 // 6007 // It is not required to check whether the object has been found dead by marking 6008 // or not, in fact it would prevent reclamation within a concurrent cycle, as 6009 // all objects allocated during that time are considered live. 6010 // SATB marking is even more conservative than the remembered set. 6011 // So if at this point in the collection there is no remembered set entry, 6012 // nobody has a reference to it. 6013 // At the start of collection we flush all refinement logs, and remembered sets 6014 // are completely up-to-date wrt to references to the humongous object. 6015 // 6016 // Other implementation considerations: 6017 // - never consider object arrays at this time because they would pose 6018 // considerable effort for cleaning up the the remembered sets. This is 6019 // required because stale remembered sets might reference locations that 6020 // are currently allocated into. 6021 uint region_idx = r->hrm_index(); 6022 if (g1h->humongous_is_live(region_idx) || 6023 g1h->humongous_region_is_always_live(region_idx)) { 6024 6025 if (G1TraceEagerReclaimHumongousObjects) { 6026 gclog_or_tty->print_cr("Live humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d", 6027 region_idx, 6028 obj->size()*HeapWordSize, 6029 r->bottom(), 6030 r->region_num(), 6031 r->rem_set()->occupied(), 6032 r->rem_set()->strong_code_roots_list_length(), 6033 next_bitmap->isMarked(r->bottom()), 6034 g1h->humongous_is_live(region_idx), 6035 obj->is_objArray() 6036 ); 6037 } 6038 6039 return false; 6040 } 6041 6042 guarantee(!obj->is_objArray(), 6043 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.", 6044 r->bottom())); 6045 6046 if (G1TraceEagerReclaimHumongousObjects) { 6047 gclog_or_tty->print_cr("Dead humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d", 6048 region_idx, 6049 obj->size()*HeapWordSize, 6050 r->bottom(), 6051 r->region_num(), 6052 r->rem_set()->occupied(), 6053 r->rem_set()->strong_code_roots_list_length(), 6054 next_bitmap->isMarked(r->bottom()), 6055 g1h->humongous_is_live(region_idx), 6056 obj->is_objArray() 6057 ); 6058 } 6059 // Need to clear mark bit of the humongous object if already set. 6060 if (next_bitmap->isMarked(r->bottom())) { 6061 next_bitmap->clear(r->bottom()); 6062 } 6063 _freed_bytes += r->used(); 6064 r->set_containing_set(NULL); 6065 _humongous_regions_removed.increment(1u, r->capacity()); 6066 g1h->free_humongous_region(r, _free_region_list, false); 6067 6068 return false; 6069 } 6070 6071 HeapRegionSetCount& humongous_free_count() { 6072 return _humongous_regions_removed; 6073 } 6074 6075 size_t bytes_freed() const { 6076 return _freed_bytes; 6077 } 6078 6079 size_t humongous_reclaimed() const { 6080 return _humongous_regions_removed.length(); 6081 } 6082 }; 6083 6084 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 6085 assert_at_safepoint(true); 6086 6087 if (!G1EagerReclaimHumongousObjects || 6088 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) { 6089 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 6090 return; 6091 } 6092 6093 double start_time = os::elapsedTime(); 6094 6095 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 6096 6097 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 6098 heap_region_iterate(&cl); 6099 6100 HeapRegionSetCount empty_set; 6101 remove_from_old_sets(empty_set, cl.humongous_free_count()); 6102 6103 G1HRPrinter* hr_printer = _g1h->hr_printer(); 6104 if (hr_printer->is_active()) { 6105 FreeRegionListIterator iter(&local_cleanup_list); 6106 while (iter.more_available()) { 6107 HeapRegion* hr = iter.get_next(); 6108 hr_printer->cleanup(hr); 6109 } 6110 } 6111 6112 prepend_to_freelist(&local_cleanup_list); 6113 decrement_summary_bytes(cl.bytes_freed()); 6114 6115 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 6116 cl.humongous_reclaimed()); 6117 } 6118 6119 // This routine is similar to the above but does not record 6120 // any policy statistics or update free lists; we are abandoning 6121 // the current incremental collection set in preparation of a 6122 // full collection. After the full GC we will start to build up 6123 // the incremental collection set again. 6124 // This is only called when we're doing a full collection 6125 // and is immediately followed by the tearing down of the young list. 6126 6127 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6128 HeapRegion* cur = cs_head; 6129 6130 while (cur != NULL) { 6131 HeapRegion* next = cur->next_in_collection_set(); 6132 assert(cur->in_collection_set(), "bad CS"); 6133 cur->set_next_in_collection_set(NULL); 6134 clear_in_cset(cur); 6135 cur->set_young_index_in_cset(-1); 6136 cur = next; 6137 } 6138 } 6139 6140 void G1CollectedHeap::set_free_regions_coming() { 6141 if (G1ConcRegionFreeingVerbose) { 6142 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6143 "setting free regions coming"); 6144 } 6145 6146 assert(!free_regions_coming(), "pre-condition"); 6147 _free_regions_coming = true; 6148 } 6149 6150 void G1CollectedHeap::reset_free_regions_coming() { 6151 assert(free_regions_coming(), "pre-condition"); 6152 6153 { 6154 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6155 _free_regions_coming = false; 6156 SecondaryFreeList_lock->notify_all(); 6157 } 6158 6159 if (G1ConcRegionFreeingVerbose) { 6160 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6161 "reset free regions coming"); 6162 } 6163 } 6164 6165 void G1CollectedHeap::wait_while_free_regions_coming() { 6166 // Most of the time we won't have to wait, so let's do a quick test 6167 // first before we take the lock. 6168 if (!free_regions_coming()) { 6169 return; 6170 } 6171 6172 if (G1ConcRegionFreeingVerbose) { 6173 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6174 "waiting for free regions"); 6175 } 6176 6177 { 6178 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6179 while (free_regions_coming()) { 6180 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6181 } 6182 } 6183 6184 if (G1ConcRegionFreeingVerbose) { 6185 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6186 "done waiting for free regions"); 6187 } 6188 } 6189 6190 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6191 assert(heap_lock_held_for_gc(), 6192 "the heap lock should already be held by or for this thread"); 6193 _young_list->push_region(hr); 6194 } 6195 6196 class NoYoungRegionsClosure: public HeapRegionClosure { 6197 private: 6198 bool _success; 6199 public: 6200 NoYoungRegionsClosure() : _success(true) { } 6201 bool doHeapRegion(HeapRegion* r) { 6202 if (r->is_young()) { 6203 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6204 r->bottom(), r->end()); 6205 _success = false; 6206 } 6207 return false; 6208 } 6209 bool success() { return _success; } 6210 }; 6211 6212 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6213 bool ret = _young_list->check_list_empty(check_sample); 6214 6215 if (check_heap) { 6216 NoYoungRegionsClosure closure; 6217 heap_region_iterate(&closure); 6218 ret = ret && closure.success(); 6219 } 6220 6221 return ret; 6222 } 6223 6224 class TearDownRegionSetsClosure : public HeapRegionClosure { 6225 private: 6226 HeapRegionSet *_old_set; 6227 6228 public: 6229 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6230 6231 bool doHeapRegion(HeapRegion* r) { 6232 if (r->is_old()) { 6233 _old_set->remove(r); 6234 } else { 6235 // We ignore free regions, we'll empty the free list afterwards. 6236 // We ignore young regions, we'll empty the young list afterwards. 6237 // We ignore humongous regions, we're not tearing down the 6238 // humongous regions set. 6239 assert(r->is_free() || r->is_young() || r->is_humongous(), 6240 "it cannot be another type"); 6241 } 6242 return false; 6243 } 6244 6245 ~TearDownRegionSetsClosure() { 6246 assert(_old_set->is_empty(), "post-condition"); 6247 } 6248 }; 6249 6250 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6251 assert_at_safepoint(true /* should_be_vm_thread */); 6252 6253 if (!free_list_only) { 6254 TearDownRegionSetsClosure cl(&_old_set); 6255 heap_region_iterate(&cl); 6256 6257 // Note that emptying the _young_list is postponed and instead done as 6258 // the first step when rebuilding the regions sets again. The reason for 6259 // this is that during a full GC string deduplication needs to know if 6260 // a collected region was young or old when the full GC was initiated. 6261 } 6262 _hrm.remove_all_free_regions(); 6263 } 6264 6265 class RebuildRegionSetsClosure : public HeapRegionClosure { 6266 private: 6267 bool _free_list_only; 6268 HeapRegionSet* _old_set; 6269 HeapRegionManager* _hrm; 6270 size_t _total_used; 6271 6272 public: 6273 RebuildRegionSetsClosure(bool free_list_only, 6274 HeapRegionSet* old_set, HeapRegionManager* hrm) : 6275 _free_list_only(free_list_only), 6276 _old_set(old_set), _hrm(hrm), _total_used(0) { 6277 assert(_hrm->num_free_regions() == 0, "pre-condition"); 6278 if (!free_list_only) { 6279 assert(_old_set->is_empty(), "pre-condition"); 6280 } 6281 } 6282 6283 bool doHeapRegion(HeapRegion* r) { 6284 if (r->is_continues_humongous()) { 6285 return false; 6286 } 6287 6288 if (r->is_empty()) { 6289 // Add free regions to the free list 6290 r->set_free(); 6291 r->set_allocation_context(AllocationContext::system()); 6292 _hrm->insert_into_free_list(r); 6293 } else if (!_free_list_only) { 6294 assert(!r->is_young(), "we should not come across young regions"); 6295 6296 if (r->is_humongous()) { 6297 // We ignore humongous regions, we left the humongous set unchanged 6298 } else { 6299 // Objects that were compacted would have ended up on regions 6300 // that were previously old or free. 6301 assert(r->is_free() || r->is_old(), "invariant"); 6302 // We now consider them old, so register as such. 6303 r->set_old(); 6304 _old_set->add(r); 6305 } 6306 _total_used += r->used(); 6307 } 6308 6309 return false; 6310 } 6311 6312 size_t total_used() { 6313 return _total_used; 6314 } 6315 }; 6316 6317 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6318 assert_at_safepoint(true /* should_be_vm_thread */); 6319 6320 if (!free_list_only) { 6321 _young_list->empty_list(); 6322 } 6323 6324 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 6325 heap_region_iterate(&cl); 6326 6327 if (!free_list_only) { 6328 _allocator->set_used(cl.total_used()); 6329 } 6330 assert(_allocator->used_unlocked() == recalculate_used(), 6331 err_msg("inconsistent _allocator->used_unlocked(), " 6332 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6333 _allocator->used_unlocked(), recalculate_used())); 6334 } 6335 6336 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6337 _refine_cte_cl->set_concurrent(concurrent); 6338 } 6339 6340 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6341 HeapRegion* hr = heap_region_containing(p); 6342 return hr->is_in(p); 6343 } 6344 6345 // Methods for the mutator alloc region 6346 6347 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6348 bool force) { 6349 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6350 assert(!force || g1_policy()->can_expand_young_list(), 6351 "if force is true we should be able to expand the young list"); 6352 bool young_list_full = g1_policy()->is_young_list_full(); 6353 if (force || !young_list_full) { 6354 HeapRegion* new_alloc_region = new_region(word_size, 6355 false /* is_old */, 6356 false /* do_expand */); 6357 if (new_alloc_region != NULL) { 6358 set_region_short_lived_locked(new_alloc_region); 6359 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6360 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6361 return new_alloc_region; 6362 } 6363 } 6364 return NULL; 6365 } 6366 6367 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6368 size_t allocated_bytes) { 6369 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6370 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 6371 6372 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6373 _allocator->increase_used(allocated_bytes); 6374 _hr_printer.retire(alloc_region); 6375 // We update the eden sizes here, when the region is retired, 6376 // instead of when it's allocated, since this is the point that its 6377 // used space has been recored in _summary_bytes_used. 6378 g1mm()->update_eden_size(); 6379 } 6380 6381 void G1CollectedHeap::set_par_threads() { 6382 // Don't change the number of workers. Use the value previously set 6383 // in the workgroup. 6384 uint n_workers = workers()->active_workers(); 6385 assert(UseDynamicNumberOfGCThreads || 6386 n_workers == workers()->total_workers(), 6387 "Otherwise should be using the total number of workers"); 6388 if (n_workers == 0) { 6389 assert(false, "Should have been set in prior evacuation pause."); 6390 n_workers = ParallelGCThreads; 6391 workers()->set_active_workers(n_workers); 6392 } 6393 set_par_threads(n_workers); 6394 } 6395 6396 // Methods for the GC alloc regions 6397 6398 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6399 uint count, 6400 InCSetState dest) { 6401 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6402 6403 if (count < g1_policy()->max_regions(dest)) { 6404 const bool is_survivor = (dest.is_young()); 6405 HeapRegion* new_alloc_region = new_region(word_size, 6406 !is_survivor, 6407 true /* do_expand */); 6408 if (new_alloc_region != NULL) { 6409 // We really only need to do this for old regions given that we 6410 // should never scan survivors. But it doesn't hurt to do it 6411 // for survivors too. 6412 new_alloc_region->record_timestamp(); 6413 if (is_survivor) { 6414 new_alloc_region->set_survivor(); 6415 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6416 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6417 } else { 6418 new_alloc_region->set_old(); 6419 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6420 check_bitmaps("Old Region Allocation", new_alloc_region); 6421 } 6422 bool during_im = g1_policy()->during_initial_mark_pause(); 6423 new_alloc_region->note_start_of_copying(during_im); 6424 return new_alloc_region; 6425 } 6426 } 6427 return NULL; 6428 } 6429 6430 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6431 size_t allocated_bytes, 6432 InCSetState dest) { 6433 bool during_im = g1_policy()->during_initial_mark_pause(); 6434 alloc_region->note_end_of_copying(during_im); 6435 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6436 if (dest.is_young()) { 6437 young_list()->add_survivor_region(alloc_region); 6438 } else { 6439 _old_set.add(alloc_region); 6440 } 6441 _hr_printer.retire(alloc_region); 6442 } 6443 6444 // Heap region set verification 6445 6446 class VerifyRegionListsClosure : public HeapRegionClosure { 6447 private: 6448 HeapRegionSet* _old_set; 6449 HeapRegionSet* _humongous_set; 6450 HeapRegionManager* _hrm; 6451 6452 public: 6453 HeapRegionSetCount _old_count; 6454 HeapRegionSetCount _humongous_count; 6455 HeapRegionSetCount _free_count; 6456 6457 VerifyRegionListsClosure(HeapRegionSet* old_set, 6458 HeapRegionSet* humongous_set, 6459 HeapRegionManager* hrm) : 6460 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm), 6461 _old_count(), _humongous_count(), _free_count(){ } 6462 6463 bool doHeapRegion(HeapRegion* hr) { 6464 if (hr->is_continues_humongous()) { 6465 return false; 6466 } 6467 6468 if (hr->is_young()) { 6469 // TODO 6470 } else if (hr->is_starts_humongous()) { 6471 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index())); 6472 _humongous_count.increment(1u, hr->capacity()); 6473 } else if (hr->is_empty()) { 6474 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index())); 6475 _free_count.increment(1u, hr->capacity()); 6476 } else if (hr->is_old()) { 6477 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index())); 6478 _old_count.increment(1u, hr->capacity()); 6479 } else { 6480 ShouldNotReachHere(); 6481 } 6482 return false; 6483 } 6484 6485 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) { 6486 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 6487 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6488 old_set->total_capacity_bytes(), _old_count.capacity())); 6489 6490 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 6491 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6492 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 6493 6494 guarantee(free_list->num_free_regions() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count.length())); 6495 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6496 free_list->total_capacity_bytes(), _free_count.capacity())); 6497 } 6498 }; 6499 6500 void G1CollectedHeap::verify_region_sets() { 6501 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6502 6503 // First, check the explicit lists. 6504 _hrm.verify(); 6505 { 6506 // Given that a concurrent operation might be adding regions to 6507 // the secondary free list we have to take the lock before 6508 // verifying it. 6509 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6510 _secondary_free_list.verify_list(); 6511 } 6512 6513 // If a concurrent region freeing operation is in progress it will 6514 // be difficult to correctly attributed any free regions we come 6515 // across to the correct free list given that they might belong to 6516 // one of several (free_list, secondary_free_list, any local lists, 6517 // etc.). So, if that's the case we will skip the rest of the 6518 // verification operation. Alternatively, waiting for the concurrent 6519 // operation to complete will have a non-trivial effect on the GC's 6520 // operation (no concurrent operation will last longer than the 6521 // interval between two calls to verification) and it might hide 6522 // any issues that we would like to catch during testing. 6523 if (free_regions_coming()) { 6524 return; 6525 } 6526 6527 // Make sure we append the secondary_free_list on the free_list so 6528 // that all free regions we will come across can be safely 6529 // attributed to the free_list. 6530 append_secondary_free_list_if_not_empty_with_lock(); 6531 6532 // Finally, make sure that the region accounting in the lists is 6533 // consistent with what we see in the heap. 6534 6535 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm); 6536 heap_region_iterate(&cl); 6537 cl.verify_counts(&_old_set, &_humongous_set, &_hrm); 6538 } 6539 6540 // Optimized nmethod scanning 6541 6542 class RegisterNMethodOopClosure: public OopClosure { 6543 G1CollectedHeap* _g1h; 6544 nmethod* _nm; 6545 6546 template <class T> void do_oop_work(T* p) { 6547 T heap_oop = oopDesc::load_heap_oop(p); 6548 if (!oopDesc::is_null(heap_oop)) { 6549 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6550 HeapRegion* hr = _g1h->heap_region_containing(obj); 6551 assert(!hr->is_continues_humongous(), 6552 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6553 " starting at "HR_FORMAT, 6554 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6555 6556 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 6557 hr->add_strong_code_root_locked(_nm); 6558 } 6559 } 6560 6561 public: 6562 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6563 _g1h(g1h), _nm(nm) {} 6564 6565 void do_oop(oop* p) { do_oop_work(p); } 6566 void do_oop(narrowOop* p) { do_oop_work(p); } 6567 }; 6568 6569 class UnregisterNMethodOopClosure: public OopClosure { 6570 G1CollectedHeap* _g1h; 6571 nmethod* _nm; 6572 6573 template <class T> void do_oop_work(T* p) { 6574 T heap_oop = oopDesc::load_heap_oop(p); 6575 if (!oopDesc::is_null(heap_oop)) { 6576 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6577 HeapRegion* hr = _g1h->heap_region_containing(obj); 6578 assert(!hr->is_continues_humongous(), 6579 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6580 " starting at "HR_FORMAT, 6581 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6582 6583 hr->remove_strong_code_root(_nm); 6584 } 6585 } 6586 6587 public: 6588 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6589 _g1h(g1h), _nm(nm) {} 6590 6591 void do_oop(oop* p) { do_oop_work(p); } 6592 void do_oop(narrowOop* p) { do_oop_work(p); } 6593 }; 6594 6595 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6596 CollectedHeap::register_nmethod(nm); 6597 6598 guarantee(nm != NULL, "sanity"); 6599 RegisterNMethodOopClosure reg_cl(this, nm); 6600 nm->oops_do(®_cl); 6601 } 6602 6603 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6604 CollectedHeap::unregister_nmethod(nm); 6605 6606 guarantee(nm != NULL, "sanity"); 6607 UnregisterNMethodOopClosure reg_cl(this, nm); 6608 nm->oops_do(®_cl, true); 6609 } 6610 6611 void G1CollectedHeap::purge_code_root_memory() { 6612 double purge_start = os::elapsedTime(); 6613 G1CodeRootSet::purge(); 6614 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6615 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6616 } 6617 6618 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6619 G1CollectedHeap* _g1h; 6620 6621 public: 6622 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6623 _g1h(g1h) {} 6624 6625 void do_code_blob(CodeBlob* cb) { 6626 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6627 if (nm == NULL) { 6628 return; 6629 } 6630 6631 if (ScavengeRootsInCode) { 6632 _g1h->register_nmethod(nm); 6633 } 6634 } 6635 }; 6636 6637 void G1CollectedHeap::rebuild_strong_code_roots() { 6638 RebuildStrongCodeRootClosure blob_cl(this); 6639 CodeCache::blobs_do(&blob_cl); 6640 }