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 "runtime/atomic.inline.hpp" 70 #include "runtime/orderAccess.inline.hpp" 71 #include "runtime/vmThread.hpp" 72 #include "utilities/globalDefinitions.hpp" 73 74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 75 76 // turn it on so that the contents of the young list (scan-only / 77 // to-be-collected) are printed at "strategic" points before / during 78 // / after the collection --- this is useful for debugging 79 #define YOUNG_LIST_VERBOSE 0 80 // CURRENT STATUS 81 // This file is under construction. Search for "FIXME". 82 83 // INVARIANTS/NOTES 84 // 85 // All allocation activity covered by the G1CollectedHeap interface is 86 // serialized by acquiring the HeapLock. This happens in mem_allocate 87 // and allocate_new_tlab, which are the "entry" points to the 88 // allocation code from the rest of the JVM. (Note that this does not 89 // apply to TLAB allocation, which is not part of this interface: it 90 // is done by clients of this interface.) 91 92 // Local to this file. 93 94 class RefineCardTableEntryClosure: public CardTableEntryClosure { 95 bool _concurrent; 96 public: 97 RefineCardTableEntryClosure() : _concurrent(true) { } 98 99 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 100 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 101 // This path is executed by the concurrent refine or mutator threads, 102 // concurrently, and so we do not care if card_ptr contains references 103 // that point into the collection set. 104 assert(!oops_into_cset, "should be"); 105 106 if (_concurrent && SuspendibleThreadSet::should_yield()) { 107 // Caller will actually yield. 108 return false; 109 } 110 // Otherwise, we finished successfully; return true. 111 return true; 112 } 113 114 void set_concurrent(bool b) { _concurrent = b; } 115 }; 116 117 118 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 119 private: 120 size_t _num_processed; 121 122 public: 123 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { } 124 125 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 126 *card_ptr = CardTableModRefBS::dirty_card_val(); 127 _num_processed++; 128 return true; 129 } 130 131 size_t num_processed() const { return _num_processed; } 132 }; 133 134 YoungList::YoungList(G1CollectedHeap* g1h) : 135 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 136 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 137 guarantee(check_list_empty(false), "just making sure..."); 138 } 139 140 void YoungList::push_region(HeapRegion *hr) { 141 assert(!hr->is_young(), "should not already be young"); 142 assert(hr->get_next_young_region() == NULL, "cause it should!"); 143 144 hr->set_next_young_region(_head); 145 _head = hr; 146 147 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 148 ++_length; 149 } 150 151 void YoungList::add_survivor_region(HeapRegion* hr) { 152 assert(hr->is_survivor(), "should be flagged as survivor region"); 153 assert(hr->get_next_young_region() == NULL, "cause it should!"); 154 155 hr->set_next_young_region(_survivor_head); 156 if (_survivor_head == NULL) { 157 _survivor_tail = hr; 158 } 159 _survivor_head = hr; 160 ++_survivor_length; 161 } 162 163 void YoungList::empty_list(HeapRegion* list) { 164 while (list != NULL) { 165 HeapRegion* next = list->get_next_young_region(); 166 list->set_next_young_region(NULL); 167 list->uninstall_surv_rate_group(); 168 // This is called before a Full GC and all the non-empty / 169 // non-humongous regions at the end of the Full GC will end up as 170 // old anyway. 171 list->set_old(); 172 list = next; 173 } 174 } 175 176 void YoungList::empty_list() { 177 assert(check_list_well_formed(), "young list should be well formed"); 178 179 empty_list(_head); 180 _head = NULL; 181 _length = 0; 182 183 empty_list(_survivor_head); 184 _survivor_head = NULL; 185 _survivor_tail = NULL; 186 _survivor_length = 0; 187 188 _last_sampled_rs_lengths = 0; 189 190 assert(check_list_empty(false), "just making sure..."); 191 } 192 193 bool YoungList::check_list_well_formed() { 194 bool ret = true; 195 196 uint length = 0; 197 HeapRegion* curr = _head; 198 HeapRegion* last = NULL; 199 while (curr != NULL) { 200 if (!curr->is_young()) { 201 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " 202 "incorrectly tagged (y: %d, surv: %d)", 203 curr->bottom(), curr->end(), 204 curr->is_young(), curr->is_survivor()); 205 ret = false; 206 } 207 ++length; 208 last = curr; 209 curr = curr->get_next_young_region(); 210 } 211 ret = ret && (length == _length); 212 213 if (!ret) { 214 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 215 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 216 length, _length); 217 } 218 219 return ret; 220 } 221 222 bool YoungList::check_list_empty(bool check_sample) { 223 bool ret = true; 224 225 if (_length != 0) { 226 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 227 _length); 228 ret = false; 229 } 230 if (check_sample && _last_sampled_rs_lengths != 0) { 231 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 232 ret = false; 233 } 234 if (_head != NULL) { 235 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 236 ret = false; 237 } 238 if (!ret) { 239 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 240 } 241 242 return ret; 243 } 244 245 void 246 YoungList::rs_length_sampling_init() { 247 _sampled_rs_lengths = 0; 248 _curr = _head; 249 } 250 251 bool 252 YoungList::rs_length_sampling_more() { 253 return _curr != NULL; 254 } 255 256 void 257 YoungList::rs_length_sampling_next() { 258 assert( _curr != NULL, "invariant" ); 259 size_t rs_length = _curr->rem_set()->occupied(); 260 261 _sampled_rs_lengths += rs_length; 262 263 // The current region may not yet have been added to the 264 // incremental collection set (it gets added when it is 265 // retired as the current allocation region). 266 if (_curr->in_collection_set()) { 267 // Update the collection set policy information for this region 268 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 269 } 270 271 _curr = _curr->get_next_young_region(); 272 if (_curr == NULL) { 273 _last_sampled_rs_lengths = _sampled_rs_lengths; 274 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 275 } 276 } 277 278 void 279 YoungList::reset_auxilary_lists() { 280 guarantee( is_empty(), "young list should be empty" ); 281 assert(check_list_well_formed(), "young list should be well formed"); 282 283 // Add survivor regions to SurvRateGroup. 284 _g1h->g1_policy()->note_start_adding_survivor_regions(); 285 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 286 287 int young_index_in_cset = 0; 288 for (HeapRegion* curr = _survivor_head; 289 curr != NULL; 290 curr = curr->get_next_young_region()) { 291 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 292 293 // The region is a non-empty survivor so let's add it to 294 // the incremental collection set for the next evacuation 295 // pause. 296 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 297 young_index_in_cset += 1; 298 } 299 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 300 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 301 302 _head = _survivor_head; 303 _length = _survivor_length; 304 if (_survivor_head != NULL) { 305 assert(_survivor_tail != NULL, "cause it shouldn't be"); 306 assert(_survivor_length > 0, "invariant"); 307 _survivor_tail->set_next_young_region(NULL); 308 } 309 310 // Don't clear the survivor list handles until the start of 311 // the next evacuation pause - we need it in order to re-tag 312 // the survivor regions from this evacuation pause as 'young' 313 // at the start of the next. 314 315 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 316 317 assert(check_list_well_formed(), "young list should be well formed"); 318 } 319 320 void YoungList::print() { 321 HeapRegion* lists[] = {_head, _survivor_head}; 322 const char* names[] = {"YOUNG", "SURVIVOR"}; 323 324 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) { 325 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 326 HeapRegion *curr = lists[list]; 327 if (curr == NULL) 328 gclog_or_tty->print_cr(" empty"); 329 while (curr != NULL) { 330 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d", 331 HR_FORMAT_PARAMS(curr), 332 curr->prev_top_at_mark_start(), 333 curr->next_top_at_mark_start(), 334 curr->age_in_surv_rate_group_cond()); 335 curr = curr->get_next_young_region(); 336 } 337 } 338 339 gclog_or_tty->cr(); 340 } 341 342 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 343 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 344 } 345 346 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 347 // The from card cache is not the memory that is actually committed. So we cannot 348 // take advantage of the zero_filled parameter. 349 reset_from_card_cache(start_idx, num_regions); 350 } 351 352 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 353 { 354 // Claim the right to put the region on the dirty cards region list 355 // by installing a self pointer. 356 HeapRegion* next = hr->get_next_dirty_cards_region(); 357 if (next == NULL) { 358 HeapRegion* res = (HeapRegion*) 359 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 360 NULL); 361 if (res == NULL) { 362 HeapRegion* head; 363 do { 364 // Put the region to the dirty cards region list. 365 head = _dirty_cards_region_list; 366 next = (HeapRegion*) 367 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 368 if (next == head) { 369 assert(hr->get_next_dirty_cards_region() == hr, 370 "hr->get_next_dirty_cards_region() != hr"); 371 if (next == NULL) { 372 // The last region in the list points to itself. 373 hr->set_next_dirty_cards_region(hr); 374 } else { 375 hr->set_next_dirty_cards_region(next); 376 } 377 } 378 } while (next != head); 379 } 380 } 381 } 382 383 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 384 { 385 HeapRegion* head; 386 HeapRegion* hr; 387 do { 388 head = _dirty_cards_region_list; 389 if (head == NULL) { 390 return NULL; 391 } 392 HeapRegion* new_head = head->get_next_dirty_cards_region(); 393 if (head == new_head) { 394 // The last region. 395 new_head = NULL; 396 } 397 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 398 head); 399 } while (hr != head); 400 assert(hr != NULL, "invariant"); 401 hr->set_next_dirty_cards_region(NULL); 402 return hr; 403 } 404 405 // Returns true if the reference points to an object that 406 // can move in an incremental collection. 407 bool G1CollectedHeap::is_scavengable(const void* p) { 408 HeapRegion* hr = heap_region_containing(p); 409 return !hr->is_humongous(); 410 } 411 412 // Private class members. 413 414 G1CollectedHeap* G1CollectedHeap::_g1h; 415 416 // Private methods. 417 418 HeapRegion* 419 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 420 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 421 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 422 if (!_secondary_free_list.is_empty()) { 423 if (G1ConcRegionFreeingVerbose) { 424 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 425 "secondary_free_list has %u entries", 426 _secondary_free_list.length()); 427 } 428 // It looks as if there are free regions available on the 429 // secondary_free_list. Let's move them to the free_list and try 430 // again to allocate from it. 431 append_secondary_free_list(); 432 433 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 434 "empty we should have moved at least one entry to the free_list"); 435 HeapRegion* res = _hrm.allocate_free_region(is_old); 436 if (G1ConcRegionFreeingVerbose) { 437 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 438 "allocated "HR_FORMAT" from secondary_free_list", 439 HR_FORMAT_PARAMS(res)); 440 } 441 return res; 442 } 443 444 // Wait here until we get notified either when (a) there are no 445 // more free regions coming or (b) some regions have been moved on 446 // the secondary_free_list. 447 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 448 } 449 450 if (G1ConcRegionFreeingVerbose) { 451 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 452 "could not allocate from secondary_free_list"); 453 } 454 return NULL; 455 } 456 457 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 458 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 459 "the only time we use this to allocate a humongous region is " 460 "when we are allocating a single humongous region"); 461 462 HeapRegion* res; 463 if (G1StressConcRegionFreeing) { 464 if (!_secondary_free_list.is_empty()) { 465 if (G1ConcRegionFreeingVerbose) { 466 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 467 "forced to look at the secondary_free_list"); 468 } 469 res = new_region_try_secondary_free_list(is_old); 470 if (res != NULL) { 471 return res; 472 } 473 } 474 } 475 476 res = _hrm.allocate_free_region(is_old); 477 478 if (res == NULL) { 479 if (G1ConcRegionFreeingVerbose) { 480 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 481 "res == NULL, trying the secondary_free_list"); 482 } 483 res = new_region_try_secondary_free_list(is_old); 484 } 485 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 486 // Currently, only attempts to allocate GC alloc regions set 487 // do_expand to true. So, we should only reach here during a 488 // safepoint. If this assumption changes we might have to 489 // reconsider the use of _expand_heap_after_alloc_failure. 490 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 491 492 ergo_verbose1(ErgoHeapSizing, 493 "attempt heap expansion", 494 ergo_format_reason("region allocation request failed") 495 ergo_format_byte("allocation request"), 496 word_size * HeapWordSize); 497 if (expand(word_size * HeapWordSize)) { 498 // Given that expand() succeeded in expanding the heap, and we 499 // always expand the heap by an amount aligned to the heap 500 // region size, the free list should in theory not be empty. 501 // In either case allocate_free_region() will check for NULL. 502 res = _hrm.allocate_free_region(is_old); 503 } else { 504 _expand_heap_after_alloc_failure = false; 505 } 506 } 507 return res; 508 } 509 510 HeapWord* 511 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 512 uint num_regions, 513 size_t word_size, 514 AllocationContext_t context) { 515 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 516 assert(is_humongous(word_size), "word_size should be humongous"); 517 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 518 519 // Index of last region in the series + 1. 520 uint last = first + num_regions; 521 522 // We need to initialize the region(s) we just discovered. This is 523 // a bit tricky given that it can happen concurrently with 524 // refinement threads refining cards on these regions and 525 // potentially wanting to refine the BOT as they are scanning 526 // those cards (this can happen shortly after a cleanup; see CR 527 // 6991377). So we have to set up the region(s) carefully and in 528 // a specific order. 529 530 // The word size sum of all the regions we will allocate. 531 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 532 assert(word_size <= word_size_sum, "sanity"); 533 534 // This will be the "starts humongous" region. 535 HeapRegion* first_hr = region_at(first); 536 // The header of the new object will be placed at the bottom of 537 // the first region. 538 HeapWord* new_obj = first_hr->bottom(); 539 // This will be the new end of the first region in the series that 540 // should also match the end of the last region in the series. 541 HeapWord* new_end = new_obj + word_size_sum; 542 // This will be the new top of the first region that will reflect 543 // this allocation. 544 HeapWord* new_top = new_obj + word_size; 545 546 // First, we need to zero the header of the space that we will be 547 // allocating. When we update top further down, some refinement 548 // threads might try to scan the region. By zeroing the header we 549 // ensure that any thread that will try to scan the region will 550 // come across the zero klass word and bail out. 551 // 552 // NOTE: It would not have been correct to have used 553 // CollectedHeap::fill_with_object() and make the space look like 554 // an int array. The thread that is doing the allocation will 555 // later update the object header to a potentially different array 556 // type and, for a very short period of time, the klass and length 557 // fields will be inconsistent. This could cause a refinement 558 // thread to calculate the object size incorrectly. 559 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 560 561 // We will set up the first region as "starts humongous". This 562 // will also update the BOT covering all the regions to reflect 563 // that there is a single object that starts at the bottom of the 564 // first region. 565 first_hr->set_starts_humongous(new_top, new_end); 566 first_hr->set_allocation_context(context); 567 // Then, if there are any, we will set up the "continues 568 // humongous" regions. 569 HeapRegion* hr = NULL; 570 for (uint i = first + 1; i < last; ++i) { 571 hr = region_at(i); 572 hr->set_continues_humongous(first_hr); 573 hr->set_allocation_context(context); 574 } 575 // If we have "continues humongous" regions (hr != NULL), then the 576 // end of the last one should match new_end. 577 assert(hr == NULL || hr->end() == new_end, "sanity"); 578 579 // Up to this point no concurrent thread would have been able to 580 // do any scanning on any region in this series. All the top 581 // fields still point to bottom, so the intersection between 582 // [bottom,top] and [card_start,card_end] will be empty. Before we 583 // update the top fields, we'll do a storestore to make sure that 584 // no thread sees the update to top before the zeroing of the 585 // object header and the BOT initialization. 586 OrderAccess::storestore(); 587 588 // Now that the BOT and the object header have been initialized, 589 // we can update top of the "starts humongous" region. 590 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 591 "new_top should be in this region"); 592 first_hr->set_top(new_top); 593 if (_hr_printer.is_active()) { 594 HeapWord* bottom = first_hr->bottom(); 595 HeapWord* end = first_hr->orig_end(); 596 if ((first + 1) == last) { 597 // the series has a single humongous region 598 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 599 } else { 600 // the series has more than one humongous regions 601 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 602 } 603 } 604 605 // Now, we will update the top fields of the "continues humongous" 606 // regions. The reason we need to do this is that, otherwise, 607 // these regions would look empty and this will confuse parts of 608 // G1. For example, the code that looks for a consecutive number 609 // of empty regions will consider them empty and try to 610 // re-allocate them. We can extend is_empty() to also include 611 // !is_continues_humongous(), but it is easier to just update the top 612 // fields here. The way we set top for all regions (i.e., top == 613 // end for all regions but the last one, top == new_top for the 614 // last one) is actually used when we will free up the humongous 615 // region in free_humongous_region(). 616 hr = NULL; 617 for (uint i = first + 1; i < last; ++i) { 618 hr = region_at(i); 619 if ((i + 1) == last) { 620 // last continues humongous region 621 assert(hr->bottom() < new_top && new_top <= hr->end(), 622 "new_top should fall on this region"); 623 hr->set_top(new_top); 624 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 625 } else { 626 // not last one 627 assert(new_top > hr->end(), "new_top should be above this region"); 628 hr->set_top(hr->end()); 629 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 630 } 631 } 632 // If we have continues humongous regions (hr != NULL), then the 633 // end of the last one should match new_end and its top should 634 // match new_top. 635 assert(hr == NULL || 636 (hr->end() == new_end && hr->top() == new_top), "sanity"); 637 check_bitmaps("Humongous Region Allocation", first_hr); 638 639 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 640 _allocator->increase_used(first_hr->used()); 641 _humongous_set.add(first_hr); 642 643 return new_obj; 644 } 645 646 // If could fit into free regions w/o expansion, try. 647 // Otherwise, if can expand, do so. 648 // Otherwise, if using ex regions might help, try with ex given back. 649 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 650 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 651 652 verify_region_sets_optional(); 653 654 uint first = G1_NO_HRM_INDEX; 655 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords); 656 657 if (obj_regions == 1) { 658 // Only one region to allocate, try to use a fast path by directly allocating 659 // from the free lists. Do not try to expand here, we will potentially do that 660 // later. 661 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 662 if (hr != NULL) { 663 first = hr->hrm_index(); 664 } 665 } else { 666 // We can't allocate humongous regions spanning more than one region while 667 // cleanupComplete() is running, since some of the regions we find to be 668 // empty might not yet be added to the free list. It is not straightforward 669 // to know in which list they are on so that we can remove them. We only 670 // need to do this if we need to allocate more than one region to satisfy the 671 // current humongous allocation request. If we are only allocating one region 672 // we use the one-region region allocation code (see above), that already 673 // potentially waits for regions from the secondary free list. 674 wait_while_free_regions_coming(); 675 append_secondary_free_list_if_not_empty_with_lock(); 676 677 // Policy: Try only empty regions (i.e. already committed first). Maybe we 678 // are lucky enough to find some. 679 first = _hrm.find_contiguous_only_empty(obj_regions); 680 if (first != G1_NO_HRM_INDEX) { 681 _hrm.allocate_free_regions_starting_at(first, obj_regions); 682 } 683 } 684 685 if (first == G1_NO_HRM_INDEX) { 686 // Policy: We could not find enough regions for the humongous object in the 687 // free list. Look through the heap to find a mix of free and uncommitted regions. 688 // If so, try expansion. 689 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 690 if (first != G1_NO_HRM_INDEX) { 691 // We found something. Make sure these regions are committed, i.e. expand 692 // the heap. Alternatively we could do a defragmentation GC. 693 ergo_verbose1(ErgoHeapSizing, 694 "attempt heap expansion", 695 ergo_format_reason("humongous allocation request failed") 696 ergo_format_byte("allocation request"), 697 word_size * HeapWordSize); 698 699 _hrm.expand_at(first, obj_regions); 700 g1_policy()->record_new_heap_size(num_regions()); 701 702 #ifdef ASSERT 703 for (uint i = first; i < first + obj_regions; ++i) { 704 HeapRegion* hr = region_at(i); 705 assert(hr->is_free(), "sanity"); 706 assert(hr->is_empty(), "sanity"); 707 assert(is_on_master_free_list(hr), "sanity"); 708 } 709 #endif 710 _hrm.allocate_free_regions_starting_at(first, obj_regions); 711 } else { 712 // Policy: Potentially trigger a defragmentation GC. 713 } 714 } 715 716 HeapWord* result = NULL; 717 if (first != G1_NO_HRM_INDEX) { 718 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 719 word_size, context); 720 assert(result != NULL, "it should always return a valid result"); 721 722 // A successful humongous object allocation changes the used space 723 // information of the old generation so we need to recalculate the 724 // sizes and update the jstat counters here. 725 g1mm()->update_sizes(); 726 } 727 728 verify_region_sets_optional(); 729 730 return result; 731 } 732 733 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 734 assert_heap_not_locked_and_not_at_safepoint(); 735 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 736 737 uint dummy_gc_count_before; 738 uint dummy_gclocker_retry_count = 0; 739 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 740 } 741 742 HeapWord* 743 G1CollectedHeap::mem_allocate(size_t word_size, 744 bool* gc_overhead_limit_was_exceeded) { 745 assert_heap_not_locked_and_not_at_safepoint(); 746 747 // Loop until the allocation is satisfied, or unsatisfied after GC. 748 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 749 uint gc_count_before; 750 751 HeapWord* result = NULL; 752 if (!is_humongous(word_size)) { 753 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 754 } else { 755 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 756 } 757 if (result != NULL) { 758 return result; 759 } 760 761 // Create the garbage collection operation... 762 VM_G1CollectForAllocation op(gc_count_before, word_size); 763 op.set_allocation_context(AllocationContext::current()); 764 765 // ...and get the VM thread to execute it. 766 VMThread::execute(&op); 767 768 if (op.prologue_succeeded() && op.pause_succeeded()) { 769 // If the operation was successful we'll return the result even 770 // if it is NULL. If the allocation attempt failed immediately 771 // after a Full GC, it's unlikely we'll be able to allocate now. 772 HeapWord* result = op.result(); 773 if (result != NULL && !is_humongous(word_size)) { 774 // Allocations that take place on VM operations do not do any 775 // card dirtying and we have to do it here. We only have to do 776 // this for non-humongous allocations, though. 777 dirty_young_block(result, word_size); 778 } 779 return result; 780 } else { 781 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 782 return NULL; 783 } 784 assert(op.result() == NULL, 785 "the result should be NULL if the VM op did not succeed"); 786 } 787 788 // Give a warning if we seem to be looping forever. 789 if ((QueuedAllocationWarningCount > 0) && 790 (try_count % QueuedAllocationWarningCount == 0)) { 791 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 792 } 793 } 794 795 ShouldNotReachHere(); 796 return NULL; 797 } 798 799 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 800 AllocationContext_t context, 801 uint* gc_count_before_ret, 802 uint* gclocker_retry_count_ret) { 803 // Make sure you read the note in attempt_allocation_humongous(). 804 805 assert_heap_not_locked_and_not_at_safepoint(); 806 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 807 "be called for humongous allocation requests"); 808 809 // We should only get here after the first-level allocation attempt 810 // (attempt_allocation()) failed to allocate. 811 812 // We will loop until a) we manage to successfully perform the 813 // allocation or b) we successfully schedule a collection which 814 // fails to perform the allocation. b) is the only case when we'll 815 // return NULL. 816 HeapWord* result = NULL; 817 for (int try_count = 1; /* we'll return */; try_count += 1) { 818 bool should_try_gc; 819 uint gc_count_before; 820 821 { 822 MutexLockerEx x(Heap_lock); 823 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, 824 false /* bot_updates */); 825 if (result != NULL) { 826 return result; 827 } 828 829 // If we reach here, attempt_allocation_locked() above failed to 830 // allocate a new region. So the mutator alloc region should be NULL. 831 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here"); 832 833 if (GC_locker::is_active_and_needs_gc()) { 834 if (g1_policy()->can_expand_young_list()) { 835 // No need for an ergo verbose message here, 836 // can_expand_young_list() does this when it returns true. 837 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size, 838 false /* bot_updates */); 839 if (result != NULL) { 840 return result; 841 } 842 } 843 should_try_gc = false; 844 } else { 845 // The GCLocker may not be active but the GCLocker initiated 846 // GC may not yet have been performed (GCLocker::needs_gc() 847 // returns true). In this case we do not try this GC and 848 // wait until the GCLocker initiated GC is performed, and 849 // then retry the allocation. 850 if (GC_locker::needs_gc()) { 851 should_try_gc = false; 852 } else { 853 // Read the GC count while still holding the Heap_lock. 854 gc_count_before = total_collections(); 855 should_try_gc = true; 856 } 857 } 858 } 859 860 if (should_try_gc) { 861 bool succeeded; 862 result = do_collection_pause(word_size, gc_count_before, &succeeded, 863 GCCause::_g1_inc_collection_pause); 864 if (result != NULL) { 865 assert(succeeded, "only way to get back a non-NULL result"); 866 return result; 867 } 868 869 if (succeeded) { 870 // If we get here we successfully scheduled a collection which 871 // failed to allocate. No point in trying to allocate 872 // further. We'll just return NULL. 873 MutexLockerEx x(Heap_lock); 874 *gc_count_before_ret = total_collections(); 875 return NULL; 876 } 877 } else { 878 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 879 MutexLockerEx x(Heap_lock); 880 *gc_count_before_ret = total_collections(); 881 return NULL; 882 } 883 // The GCLocker is either active or the GCLocker initiated 884 // GC has not yet been performed. Stall until it is and 885 // then retry the allocation. 886 GC_locker::stall_until_clear(); 887 (*gclocker_retry_count_ret) += 1; 888 } 889 890 // We can reach here if we were unsuccessful in scheduling a 891 // collection (because another thread beat us to it) or if we were 892 // stalled due to the GC locker. In either can we should retry the 893 // allocation attempt in case another thread successfully 894 // performed a collection and reclaimed enough space. We do the 895 // first attempt (without holding the Heap_lock) here and the 896 // follow-on attempt will be at the start of the next loop 897 // iteration (after taking the Heap_lock). 898 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size, 899 false /* bot_updates */); 900 if (result != NULL) { 901 return result; 902 } 903 904 // Give a warning if we seem to be looping forever. 905 if ((QueuedAllocationWarningCount > 0) && 906 (try_count % QueuedAllocationWarningCount == 0)) { 907 warning("G1CollectedHeap::attempt_allocation_slow() " 908 "retries %d times", try_count); 909 } 910 } 911 912 ShouldNotReachHere(); 913 return NULL; 914 } 915 916 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 917 uint* gc_count_before_ret, 918 uint* gclocker_retry_count_ret) { 919 // The structure of this method has a lot of similarities to 920 // attempt_allocation_slow(). The reason these two were not merged 921 // into a single one is that such a method would require several "if 922 // allocation is not humongous do this, otherwise do that" 923 // conditional paths which would obscure its flow. In fact, an early 924 // version of this code did use a unified method which was harder to 925 // follow and, as a result, it had subtle bugs that were hard to 926 // track down. So keeping these two methods separate allows each to 927 // be more readable. It will be good to keep these two in sync as 928 // much as possible. 929 930 assert_heap_not_locked_and_not_at_safepoint(); 931 assert(is_humongous(word_size), "attempt_allocation_humongous() " 932 "should only be called for humongous allocations"); 933 934 // Humongous objects can exhaust the heap quickly, so we should check if we 935 // need to start a marking cycle at each humongous object allocation. We do 936 // the check before we do the actual allocation. The reason for doing it 937 // before the allocation is that we avoid having to keep track of the newly 938 // allocated memory while we do a GC. 939 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 940 word_size)) { 941 collect(GCCause::_g1_humongous_allocation); 942 } 943 944 // We will loop until a) we manage to successfully perform the 945 // allocation or b) we successfully schedule a collection which 946 // fails to perform the allocation. b) is the only case when we'll 947 // return NULL. 948 HeapWord* result = NULL; 949 for (int try_count = 1; /* we'll return */; try_count += 1) { 950 bool should_try_gc; 951 uint gc_count_before; 952 953 { 954 MutexLockerEx x(Heap_lock); 955 956 // Given that humongous objects are not allocated in young 957 // regions, we'll first try to do the allocation without doing a 958 // collection hoping that there's enough space in the heap. 959 result = humongous_obj_allocate(word_size, AllocationContext::current()); 960 if (result != NULL) { 961 return result; 962 } 963 964 if (GC_locker::is_active_and_needs_gc()) { 965 should_try_gc = false; 966 } else { 967 // The GCLocker may not be active but the GCLocker initiated 968 // GC may not yet have been performed (GCLocker::needs_gc() 969 // returns true). In this case we do not try this GC and 970 // wait until the GCLocker initiated GC is performed, and 971 // then retry the allocation. 972 if (GC_locker::needs_gc()) { 973 should_try_gc = false; 974 } else { 975 // Read the GC count while still holding the Heap_lock. 976 gc_count_before = total_collections(); 977 should_try_gc = true; 978 } 979 } 980 } 981 982 if (should_try_gc) { 983 // If we failed to allocate the humongous object, we should try to 984 // do a collection pause (if we're allowed) in case it reclaims 985 // enough space for the allocation to succeed after the pause. 986 987 bool succeeded; 988 result = do_collection_pause(word_size, gc_count_before, &succeeded, 989 GCCause::_g1_humongous_allocation); 990 if (result != NULL) { 991 assert(succeeded, "only way to get back a non-NULL result"); 992 return result; 993 } 994 995 if (succeeded) { 996 // If we get here we successfully scheduled a collection which 997 // failed to allocate. No point in trying to allocate 998 // further. We'll just return NULL. 999 MutexLockerEx x(Heap_lock); 1000 *gc_count_before_ret = total_collections(); 1001 return NULL; 1002 } 1003 } else { 1004 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1005 MutexLockerEx x(Heap_lock); 1006 *gc_count_before_ret = total_collections(); 1007 return NULL; 1008 } 1009 // The GCLocker is either active or the GCLocker initiated 1010 // GC has not yet been performed. Stall until it is and 1011 // then retry the allocation. 1012 GC_locker::stall_until_clear(); 1013 (*gclocker_retry_count_ret) += 1; 1014 } 1015 1016 // We can reach here if we were unsuccessful in scheduling a 1017 // collection (because another thread beat us to it) or if we were 1018 // stalled due to the GC locker. In either can we should retry the 1019 // allocation attempt in case another thread successfully 1020 // performed a collection and reclaimed enough space. Give a 1021 // warning if we seem to be looping forever. 1022 1023 if ((QueuedAllocationWarningCount > 0) && 1024 (try_count % QueuedAllocationWarningCount == 0)) { 1025 warning("G1CollectedHeap::attempt_allocation_humongous() " 1026 "retries %d times", try_count); 1027 } 1028 } 1029 1030 ShouldNotReachHere(); 1031 return NULL; 1032 } 1033 1034 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1035 AllocationContext_t context, 1036 bool expect_null_mutator_alloc_region) { 1037 assert_at_safepoint(true /* should_be_vm_thread */); 1038 assert(_allocator->mutator_alloc_region(context)->get() == NULL || 1039 !expect_null_mutator_alloc_region, 1040 "the current alloc region was unexpectedly found to be non-NULL"); 1041 1042 if (!is_humongous(word_size)) { 1043 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, 1044 false /* bot_updates */); 1045 } else { 1046 HeapWord* result = humongous_obj_allocate(word_size, context); 1047 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1048 g1_policy()->set_initiate_conc_mark_if_possible(); 1049 } 1050 return result; 1051 } 1052 1053 ShouldNotReachHere(); 1054 } 1055 1056 class PostMCRemSetClearClosure: public HeapRegionClosure { 1057 G1CollectedHeap* _g1h; 1058 ModRefBarrierSet* _mr_bs; 1059 public: 1060 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1061 _g1h(g1h), _mr_bs(mr_bs) {} 1062 1063 bool doHeapRegion(HeapRegion* r) { 1064 HeapRegionRemSet* hrrs = r->rem_set(); 1065 1066 if (r->is_continues_humongous()) { 1067 // We'll assert that the strong code root list and RSet is empty 1068 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1069 assert(hrrs->occupied() == 0, "RSet should be empty"); 1070 return false; 1071 } 1072 1073 _g1h->reset_gc_time_stamps(r); 1074 hrrs->clear(); 1075 // You might think here that we could clear just the cards 1076 // corresponding to the used region. But no: if we leave a dirty card 1077 // in a region we might allocate into, then it would prevent that card 1078 // from being enqueued, and cause it to be missed. 1079 // Re: the performance cost: we shouldn't be doing full GC anyway! 1080 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1081 1082 return false; 1083 } 1084 }; 1085 1086 void G1CollectedHeap::clear_rsets_post_compaction() { 1087 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1088 heap_region_iterate(&rs_clear); 1089 } 1090 1091 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1092 G1CollectedHeap* _g1h; 1093 UpdateRSOopClosure _cl; 1094 int _worker_i; 1095 public: 1096 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) : 1097 _cl(g1->g1_rem_set(), worker_i), 1098 _worker_i(worker_i), 1099 _g1h(g1) 1100 { } 1101 1102 bool doHeapRegion(HeapRegion* r) { 1103 if (!r->is_continues_humongous()) { 1104 _cl.set_from(r); 1105 r->oop_iterate(&_cl); 1106 } 1107 return false; 1108 } 1109 }; 1110 1111 class ParRebuildRSTask: public AbstractGangTask { 1112 G1CollectedHeap* _g1; 1113 HeapRegionClaimer _hrclaimer; 1114 1115 public: 1116 ParRebuildRSTask(G1CollectedHeap* g1) : 1117 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {} 1118 1119 void work(uint worker_id) { 1120 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1121 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer); 1122 } 1123 }; 1124 1125 class PostCompactionPrinterClosure: public HeapRegionClosure { 1126 private: 1127 G1HRPrinter* _hr_printer; 1128 public: 1129 bool doHeapRegion(HeapRegion* hr) { 1130 assert(!hr->is_young(), "not expecting to find young regions"); 1131 if (hr->is_free()) { 1132 // We only generate output for non-empty regions. 1133 } else if (hr->is_starts_humongous()) { 1134 if (hr->region_num() == 1) { 1135 // single humongous region 1136 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1137 } else { 1138 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1139 } 1140 } else if (hr->is_continues_humongous()) { 1141 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1142 } else if (hr->is_old()) { 1143 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1144 } else { 1145 ShouldNotReachHere(); 1146 } 1147 return false; 1148 } 1149 1150 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1151 : _hr_printer(hr_printer) { } 1152 }; 1153 1154 void G1CollectedHeap::print_hrm_post_compaction() { 1155 PostCompactionPrinterClosure cl(hr_printer()); 1156 heap_region_iterate(&cl); 1157 } 1158 1159 bool G1CollectedHeap::do_collection(bool explicit_gc, 1160 bool clear_all_soft_refs, 1161 size_t word_size) { 1162 assert_at_safepoint(true /* should_be_vm_thread */); 1163 1164 if (GC_locker::check_active_before_gc()) { 1165 return false; 1166 } 1167 1168 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1169 gc_timer->register_gc_start(); 1170 1171 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1172 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1173 1174 SvcGCMarker sgcm(SvcGCMarker::FULL); 1175 ResourceMark rm; 1176 1177 print_heap_before_gc(); 1178 trace_heap_before_gc(gc_tracer); 1179 1180 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1181 1182 verify_region_sets_optional(); 1183 1184 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1185 collector_policy()->should_clear_all_soft_refs(); 1186 1187 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1188 1189 { 1190 IsGCActiveMark x; 1191 1192 // Timing 1193 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); 1194 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1195 1196 { 1197 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id()); 1198 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1199 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1200 1201 g1_policy()->record_full_collection_start(); 1202 1203 // Note: When we have a more flexible GC logging framework that 1204 // allows us to add optional attributes to a GC log record we 1205 // could consider timing and reporting how long we wait in the 1206 // following two methods. 1207 wait_while_free_regions_coming(); 1208 // If we start the compaction before the CM threads finish 1209 // scanning the root regions we might trip them over as we'll 1210 // be moving objects / updating references. So let's wait until 1211 // they are done. By telling them to abort, they should complete 1212 // early. 1213 _cm->root_regions()->abort(); 1214 _cm->root_regions()->wait_until_scan_finished(); 1215 append_secondary_free_list_if_not_empty_with_lock(); 1216 1217 gc_prologue(true); 1218 increment_total_collections(true /* full gc */); 1219 increment_old_marking_cycles_started(); 1220 1221 assert(used() == recalculate_used(), "Should be equal"); 1222 1223 verify_before_gc(); 1224 1225 check_bitmaps("Full GC Start"); 1226 pre_full_gc_dump(gc_timer); 1227 1228 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1229 1230 // Disable discovery and empty the discovered lists 1231 // for the CM ref processor. 1232 ref_processor_cm()->disable_discovery(); 1233 ref_processor_cm()->abandon_partial_discovery(); 1234 ref_processor_cm()->verify_no_references_recorded(); 1235 1236 // Abandon current iterations of concurrent marking and concurrent 1237 // refinement, if any are in progress. We have to do this before 1238 // wait_until_scan_finished() below. 1239 concurrent_mark()->abort(); 1240 1241 // Make sure we'll choose a new allocation region afterwards. 1242 _allocator->release_mutator_alloc_region(); 1243 _allocator->abandon_gc_alloc_regions(); 1244 g1_rem_set()->cleanupHRRS(); 1245 1246 // We should call this after we retire any currently active alloc 1247 // regions so that all the ALLOC / RETIRE events are generated 1248 // before the start GC event. 1249 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1250 1251 // We may have added regions to the current incremental collection 1252 // set between the last GC or pause and now. We need to clear the 1253 // incremental collection set and then start rebuilding it afresh 1254 // after this full GC. 1255 abandon_collection_set(g1_policy()->inc_cset_head()); 1256 g1_policy()->clear_incremental_cset(); 1257 g1_policy()->stop_incremental_cset_building(); 1258 1259 tear_down_region_sets(false /* free_list_only */); 1260 g1_policy()->set_gcs_are_young(true); 1261 1262 // See the comments in g1CollectedHeap.hpp and 1263 // G1CollectedHeap::ref_processing_init() about 1264 // how reference processing currently works in G1. 1265 1266 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1267 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1268 1269 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1270 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1271 1272 ref_processor_stw()->enable_discovery(); 1273 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1274 1275 // Do collection work 1276 { 1277 HandleMark hm; // Discard invalid handles created during gc 1278 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1279 } 1280 1281 assert(num_free_regions() == 0, "we should not have added any free regions"); 1282 rebuild_region_sets(false /* free_list_only */); 1283 1284 // Enqueue any discovered reference objects that have 1285 // not been removed from the discovered lists. 1286 ref_processor_stw()->enqueue_discovered_references(); 1287 1288 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1289 1290 MemoryService::track_memory_usage(); 1291 1292 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1293 ref_processor_stw()->verify_no_references_recorded(); 1294 1295 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1296 ClassLoaderDataGraph::purge(); 1297 MetaspaceAux::verify_metrics(); 1298 1299 // Note: since we've just done a full GC, concurrent 1300 // marking is no longer active. Therefore we need not 1301 // re-enable reference discovery for the CM ref processor. 1302 // That will be done at the start of the next marking cycle. 1303 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1304 ref_processor_cm()->verify_no_references_recorded(); 1305 1306 reset_gc_time_stamp(); 1307 // Since everything potentially moved, we will clear all remembered 1308 // sets, and clear all cards. Later we will rebuild remembered 1309 // sets. We will also reset the GC time stamps of the regions. 1310 clear_rsets_post_compaction(); 1311 check_gc_time_stamps(); 1312 1313 // Resize the heap if necessary. 1314 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1315 1316 if (_hr_printer.is_active()) { 1317 // We should do this after we potentially resize the heap so 1318 // that all the COMMIT / UNCOMMIT events are generated before 1319 // the end GC event. 1320 1321 print_hrm_post_compaction(); 1322 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1323 } 1324 1325 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1326 if (hot_card_cache->use_cache()) { 1327 hot_card_cache->reset_card_counts(); 1328 hot_card_cache->reset_hot_cache(); 1329 } 1330 1331 // Rebuild remembered sets of all regions. 1332 uint n_workers = 1333 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1334 workers()->active_workers(), 1335 Threads::number_of_non_daemon_threads()); 1336 assert(UseDynamicNumberOfGCThreads || 1337 n_workers == workers()->total_workers(), 1338 "If not dynamic should be using all the workers"); 1339 workers()->set_active_workers(n_workers); 1340 // Set parallel threads in the heap (_n_par_threads) only 1341 // before a parallel phase and always reset it to 0 after 1342 // the phase so that the number of parallel threads does 1343 // no get carried forward to a serial phase where there 1344 // may be code that is "possibly_parallel". 1345 set_par_threads(n_workers); 1346 1347 ParRebuildRSTask rebuild_rs_task(this); 1348 assert(UseDynamicNumberOfGCThreads || 1349 workers()->active_workers() == workers()->total_workers(), 1350 "Unless dynamic should use total workers"); 1351 // Use the most recent number of active workers 1352 assert(workers()->active_workers() > 0, 1353 "Active workers not properly set"); 1354 set_par_threads(workers()->active_workers()); 1355 workers()->run_task(&rebuild_rs_task); 1356 set_par_threads(0); 1357 1358 // Rebuild the strong code root lists for each region 1359 rebuild_strong_code_roots(); 1360 1361 if (true) { // FIXME 1362 MetaspaceGC::compute_new_size(); 1363 } 1364 1365 #ifdef TRACESPINNING 1366 ParallelTaskTerminator::print_termination_counts(); 1367 #endif 1368 1369 // Discard all rset updates 1370 JavaThread::dirty_card_queue_set().abandon_logs(); 1371 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1372 1373 _young_list->reset_sampled_info(); 1374 // At this point there should be no regions in the 1375 // entire heap tagged as young. 1376 assert(check_young_list_empty(true /* check_heap */), 1377 "young list should be empty at this point"); 1378 1379 // Update the number of full collections that have been completed. 1380 increment_old_marking_cycles_completed(false /* concurrent */); 1381 1382 _hrm.verify_optional(); 1383 verify_region_sets_optional(); 1384 1385 verify_after_gc(); 1386 1387 // Clear the previous marking bitmap, if needed for bitmap verification. 1388 // Note we cannot do this when we clear the next marking bitmap in 1389 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1390 // objects marked during a full GC against the previous bitmap. 1391 // But we need to clear it before calling check_bitmaps below since 1392 // the full GC has compacted objects and updated TAMS but not updated 1393 // the prev bitmap. 1394 if (G1VerifyBitmaps) { 1395 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1396 } 1397 check_bitmaps("Full GC End"); 1398 1399 // Start a new incremental collection set for the next pause 1400 assert(g1_policy()->collection_set() == NULL, "must be"); 1401 g1_policy()->start_incremental_cset_building(); 1402 1403 clear_cset_fast_test(); 1404 1405 _allocator->init_mutator_alloc_region(); 1406 1407 g1_policy()->record_full_collection_end(); 1408 1409 if (G1Log::fine()) { 1410 g1_policy()->print_heap_transition(); 1411 } 1412 1413 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1414 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1415 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1416 // before any GC notifications are raised. 1417 g1mm()->update_sizes(); 1418 1419 gc_epilogue(true); 1420 } 1421 1422 if (G1Log::finer()) { 1423 g1_policy()->print_detailed_heap_transition(true /* full */); 1424 } 1425 1426 print_heap_after_gc(); 1427 trace_heap_after_gc(gc_tracer); 1428 1429 post_full_gc_dump(gc_timer); 1430 1431 gc_timer->register_gc_end(); 1432 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1433 } 1434 1435 return true; 1436 } 1437 1438 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1439 // do_collection() will return whether it succeeded in performing 1440 // the GC. Currently, there is no facility on the 1441 // do_full_collection() API to notify the caller than the collection 1442 // did not succeed (e.g., because it was locked out by the GC 1443 // locker). So, right now, we'll ignore the return value. 1444 bool dummy = do_collection(true, /* explicit_gc */ 1445 clear_all_soft_refs, 1446 0 /* word_size */); 1447 } 1448 1449 // This code is mostly copied from TenuredGeneration. 1450 void 1451 G1CollectedHeap:: 1452 resize_if_necessary_after_full_collection(size_t word_size) { 1453 // Include the current allocation, if any, and bytes that will be 1454 // pre-allocated to support collections, as "used". 1455 const size_t used_after_gc = used(); 1456 const size_t capacity_after_gc = capacity(); 1457 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1458 1459 // This is enforced in arguments.cpp. 1460 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1461 "otherwise the code below doesn't make sense"); 1462 1463 // We don't have floating point command-line arguments 1464 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1465 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1466 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1467 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1468 1469 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1470 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1471 1472 // We have to be careful here as these two calculations can overflow 1473 // 32-bit size_t's. 1474 double used_after_gc_d = (double) used_after_gc; 1475 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1476 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1477 1478 // Let's make sure that they are both under the max heap size, which 1479 // by default will make them fit into a size_t. 1480 double desired_capacity_upper_bound = (double) max_heap_size; 1481 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1482 desired_capacity_upper_bound); 1483 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1484 desired_capacity_upper_bound); 1485 1486 // We can now safely turn them into size_t's. 1487 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1488 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1489 1490 // This assert only makes sense here, before we adjust them 1491 // with respect to the min and max heap size. 1492 assert(minimum_desired_capacity <= maximum_desired_capacity, 1493 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1494 "maximum_desired_capacity = "SIZE_FORMAT, 1495 minimum_desired_capacity, maximum_desired_capacity)); 1496 1497 // Should not be greater than the heap max size. No need to adjust 1498 // it with respect to the heap min size as it's a lower bound (i.e., 1499 // we'll try to make the capacity larger than it, not smaller). 1500 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1501 // Should not be less than the heap min size. No need to adjust it 1502 // with respect to the heap max size as it's an upper bound (i.e., 1503 // we'll try to make the capacity smaller than it, not greater). 1504 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1505 1506 if (capacity_after_gc < minimum_desired_capacity) { 1507 // Don't expand unless it's significant 1508 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1509 ergo_verbose4(ErgoHeapSizing, 1510 "attempt heap expansion", 1511 ergo_format_reason("capacity lower than " 1512 "min desired capacity after Full GC") 1513 ergo_format_byte("capacity") 1514 ergo_format_byte("occupancy") 1515 ergo_format_byte_perc("min desired capacity"), 1516 capacity_after_gc, used_after_gc, 1517 minimum_desired_capacity, (double) MinHeapFreeRatio); 1518 expand(expand_bytes); 1519 1520 // No expansion, now see if we want to shrink 1521 } else if (capacity_after_gc > maximum_desired_capacity) { 1522 // Capacity too large, compute shrinking size 1523 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1524 ergo_verbose4(ErgoHeapSizing, 1525 "attempt heap shrinking", 1526 ergo_format_reason("capacity higher than " 1527 "max desired capacity after Full GC") 1528 ergo_format_byte("capacity") 1529 ergo_format_byte("occupancy") 1530 ergo_format_byte_perc("max desired capacity"), 1531 capacity_after_gc, used_after_gc, 1532 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1533 shrink(shrink_bytes); 1534 } 1535 } 1536 1537 1538 HeapWord* 1539 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1540 AllocationContext_t context, 1541 bool* succeeded) { 1542 assert_at_safepoint(true /* should_be_vm_thread */); 1543 1544 *succeeded = true; 1545 // Let's attempt the allocation first. 1546 HeapWord* result = 1547 attempt_allocation_at_safepoint(word_size, 1548 context, 1549 false /* expect_null_mutator_alloc_region */); 1550 if (result != NULL) { 1551 assert(*succeeded, "sanity"); 1552 return result; 1553 } 1554 1555 // In a G1 heap, we're supposed to keep allocation from failing by 1556 // incremental pauses. Therefore, at least for now, we'll favor 1557 // expansion over collection. (This might change in the future if we can 1558 // do something smarter than full collection to satisfy a failed alloc.) 1559 result = expand_and_allocate(word_size, context); 1560 if (result != NULL) { 1561 assert(*succeeded, "sanity"); 1562 return result; 1563 } 1564 1565 // Expansion didn't work, we'll try to do a Full GC. 1566 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1567 false, /* clear_all_soft_refs */ 1568 word_size); 1569 if (!gc_succeeded) { 1570 *succeeded = false; 1571 return NULL; 1572 } 1573 1574 // Retry the allocation 1575 result = attempt_allocation_at_safepoint(word_size, 1576 context, 1577 true /* expect_null_mutator_alloc_region */); 1578 if (result != NULL) { 1579 assert(*succeeded, "sanity"); 1580 return result; 1581 } 1582 1583 // Then, try a Full GC that will collect all soft references. 1584 gc_succeeded = do_collection(false, /* explicit_gc */ 1585 true, /* clear_all_soft_refs */ 1586 word_size); 1587 if (!gc_succeeded) { 1588 *succeeded = false; 1589 return NULL; 1590 } 1591 1592 // Retry the allocation once more 1593 result = attempt_allocation_at_safepoint(word_size, 1594 context, 1595 true /* expect_null_mutator_alloc_region */); 1596 if (result != NULL) { 1597 assert(*succeeded, "sanity"); 1598 return result; 1599 } 1600 1601 assert(!collector_policy()->should_clear_all_soft_refs(), 1602 "Flag should have been handled and cleared prior to this point"); 1603 1604 // What else? We might try synchronous finalization later. If the total 1605 // space available is large enough for the allocation, then a more 1606 // complete compaction phase than we've tried so far might be 1607 // appropriate. 1608 assert(*succeeded, "sanity"); 1609 return NULL; 1610 } 1611 1612 // Attempting to expand the heap sufficiently 1613 // to support an allocation of the given "word_size". If 1614 // successful, perform the allocation and return the address of the 1615 // allocated block, or else "NULL". 1616 1617 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1618 assert_at_safepoint(true /* should_be_vm_thread */); 1619 1620 verify_region_sets_optional(); 1621 1622 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1623 ergo_verbose1(ErgoHeapSizing, 1624 "attempt heap expansion", 1625 ergo_format_reason("allocation request failed") 1626 ergo_format_byte("allocation request"), 1627 word_size * HeapWordSize); 1628 if (expand(expand_bytes)) { 1629 _hrm.verify_optional(); 1630 verify_region_sets_optional(); 1631 return attempt_allocation_at_safepoint(word_size, 1632 context, 1633 false /* expect_null_mutator_alloc_region */); 1634 } 1635 return NULL; 1636 } 1637 1638 bool G1CollectedHeap::expand(size_t expand_bytes) { 1639 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1640 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1641 HeapRegion::GrainBytes); 1642 ergo_verbose2(ErgoHeapSizing, 1643 "expand the heap", 1644 ergo_format_byte("requested expansion amount") 1645 ergo_format_byte("attempted expansion amount"), 1646 expand_bytes, aligned_expand_bytes); 1647 1648 if (is_maximal_no_gc()) { 1649 ergo_verbose0(ErgoHeapSizing, 1650 "did not expand the heap", 1651 ergo_format_reason("heap already fully expanded")); 1652 return false; 1653 } 1654 1655 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1656 assert(regions_to_expand > 0, "Must expand by at least one region"); 1657 1658 uint expanded_by = _hrm.expand_by(regions_to_expand); 1659 1660 if (expanded_by > 0) { 1661 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1662 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1663 g1_policy()->record_new_heap_size(num_regions()); 1664 } else { 1665 ergo_verbose0(ErgoHeapSizing, 1666 "did not expand the heap", 1667 ergo_format_reason("heap expansion operation failed")); 1668 // The expansion of the virtual storage space was unsuccessful. 1669 // Let's see if it was because we ran out of swap. 1670 if (G1ExitOnExpansionFailure && 1671 _hrm.available() >= regions_to_expand) { 1672 // We had head room... 1673 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1674 } 1675 } 1676 return regions_to_expand > 0; 1677 } 1678 1679 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1680 size_t aligned_shrink_bytes = 1681 ReservedSpace::page_align_size_down(shrink_bytes); 1682 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1683 HeapRegion::GrainBytes); 1684 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1685 1686 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1687 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1688 1689 ergo_verbose3(ErgoHeapSizing, 1690 "shrink the heap", 1691 ergo_format_byte("requested shrinking amount") 1692 ergo_format_byte("aligned shrinking amount") 1693 ergo_format_byte("attempted shrinking amount"), 1694 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1695 if (num_regions_removed > 0) { 1696 g1_policy()->record_new_heap_size(num_regions()); 1697 } else { 1698 ergo_verbose0(ErgoHeapSizing, 1699 "did not shrink the heap", 1700 ergo_format_reason("heap shrinking operation failed")); 1701 } 1702 } 1703 1704 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1705 verify_region_sets_optional(); 1706 1707 // We should only reach here at the end of a Full GC which means we 1708 // should not not be holding to any GC alloc regions. The method 1709 // below will make sure of that and do any remaining clean up. 1710 _allocator->abandon_gc_alloc_regions(); 1711 1712 // Instead of tearing down / rebuilding the free lists here, we 1713 // could instead use the remove_all_pending() method on free_list to 1714 // remove only the ones that we need to remove. 1715 tear_down_region_sets(true /* free_list_only */); 1716 shrink_helper(shrink_bytes); 1717 rebuild_region_sets(true /* free_list_only */); 1718 1719 _hrm.verify_optional(); 1720 verify_region_sets_optional(); 1721 } 1722 1723 // Public methods. 1724 1725 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1726 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1727 #endif // _MSC_VER 1728 1729 1730 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1731 SharedHeap(), 1732 _g1_policy(policy_), 1733 _dirty_card_queue_set(false), 1734 _into_cset_dirty_card_queue_set(false), 1735 _is_alive_closure_cm(this), 1736 _is_alive_closure_stw(this), 1737 _ref_processor_cm(NULL), 1738 _ref_processor_stw(NULL), 1739 _bot_shared(NULL), 1740 _evac_failure_scan_stack(NULL), 1741 _mark_in_progress(false), 1742 _cg1r(NULL), 1743 _g1mm(NULL), 1744 _refine_cte_cl(NULL), 1745 _full_collection(false), 1746 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1747 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1748 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1749 _humongous_is_live(), 1750 _has_humongous_reclaim_candidates(false), 1751 _free_regions_coming(false), 1752 _young_list(new YoungList(this)), 1753 _gc_time_stamp(0), 1754 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1755 _old_plab_stats(OldPLABSize, PLABWeight), 1756 _expand_heap_after_alloc_failure(true), 1757 _surviving_young_words(NULL), 1758 _old_marking_cycles_started(0), 1759 _old_marking_cycles_completed(0), 1760 _concurrent_cycle_started(false), 1761 _heap_summary_sent(false), 1762 _in_cset_fast_test(), 1763 _dirty_cards_region_list(NULL), 1764 _worker_cset_start_region(NULL), 1765 _worker_cset_start_region_time_stamp(NULL), 1766 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1767 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1768 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1769 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1770 1771 _g1h = this; 1772 1773 _allocator = G1Allocator::create_allocator(_g1h); 1774 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1775 1776 int n_queues = MAX2((int)ParallelGCThreads, 1); 1777 _task_queues = new RefToScanQueueSet(n_queues); 1778 1779 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1780 assert(n_rem_sets > 0, "Invariant."); 1781 1782 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1783 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC); 1784 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1785 1786 for (int i = 0; i < n_queues; i++) { 1787 RefToScanQueue* q = new RefToScanQueue(); 1788 q->initialize(); 1789 _task_queues->register_queue(i, q); 1790 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1791 } 1792 clear_cset_start_regions(); 1793 1794 // Initialize the G1EvacuationFailureALot counters and flags. 1795 NOT_PRODUCT(reset_evacuation_should_fail();) 1796 1797 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1798 } 1799 1800 jint G1CollectedHeap::initialize() { 1801 CollectedHeap::pre_initialize(); 1802 os::enable_vtime(); 1803 1804 G1Log::init(); 1805 1806 // Necessary to satisfy locking discipline assertions. 1807 1808 MutexLocker x(Heap_lock); 1809 1810 // We have to initialize the printer before committing the heap, as 1811 // it will be used then. 1812 _hr_printer.set_active(G1PrintHeapRegions); 1813 1814 // While there are no constraints in the GC code that HeapWordSize 1815 // be any particular value, there are multiple other areas in the 1816 // system which believe this to be true (e.g. oop->object_size in some 1817 // cases incorrectly returns the size in wordSize units rather than 1818 // HeapWordSize). 1819 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1820 1821 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1822 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1823 size_t heap_alignment = collector_policy()->heap_alignment(); 1824 1825 // Ensure that the sizes are properly aligned. 1826 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1827 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1828 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1829 1830 _refine_cte_cl = new RefineCardTableEntryClosure(); 1831 1832 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl); 1833 1834 // Reserve the maximum. 1835 1836 // When compressed oops are enabled, the preferred heap base 1837 // is calculated by subtracting the requested size from the 1838 // 32Gb boundary and using the result as the base address for 1839 // heap reservation. If the requested size is not aligned to 1840 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1841 // into the ReservedHeapSpace constructor) then the actual 1842 // base of the reserved heap may end up differing from the 1843 // address that was requested (i.e. the preferred heap base). 1844 // If this happens then we could end up using a non-optimal 1845 // compressed oops mode. 1846 1847 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1848 heap_alignment); 1849 1850 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1851 1852 // Create the barrier set for the entire reserved region. 1853 G1SATBCardTableLoggingModRefBS* bs 1854 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 1855 bs->initialize(); 1856 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 1857 _barrier_set = bs; 1858 oopDesc::set_bs(bs); 1859 1860 // Also create a G1 rem set. 1861 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 1862 1863 // Carve out the G1 part of the heap. 1864 1865 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1866 G1RegionToSpaceMapper* heap_storage = 1867 G1RegionToSpaceMapper::create_mapper(g1_rs, 1868 UseLargePages ? os::large_page_size() : os::vm_page_size(), 1869 HeapRegion::GrainBytes, 1870 1, 1871 mtJavaHeap); 1872 heap_storage->set_mapping_changed_listener(&_listener); 1873 1874 // Reserve space for the block offset table. We do not support automatic uncommit 1875 // for the card table at this time. BOT only. 1876 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize)); 1877 G1RegionToSpaceMapper* bot_storage = 1878 G1RegionToSpaceMapper::create_mapper(bot_rs, 1879 os::vm_page_size(), 1880 HeapRegion::GrainBytes, 1881 G1BlockOffsetSharedArray::N_bytes, 1882 mtGC); 1883 1884 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 1885 G1RegionToSpaceMapper* cardtable_storage = 1886 G1RegionToSpaceMapper::create_mapper(cardtable_rs, 1887 os::vm_page_size(), 1888 HeapRegion::GrainBytes, 1889 G1BlockOffsetSharedArray::N_bytes, 1890 mtGC); 1891 1892 // Reserve space for the card counts table. 1893 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize)); 1894 G1RegionToSpaceMapper* card_counts_storage = 1895 G1RegionToSpaceMapper::create_mapper(card_counts_rs, 1896 os::vm_page_size(), 1897 HeapRegion::GrainBytes, 1898 G1BlockOffsetSharedArray::N_bytes, 1899 mtGC); 1900 1901 // Reserve space for prev and next bitmap. 1902 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); 1903 1904 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size)); 1905 G1RegionToSpaceMapper* prev_bitmap_storage = 1906 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs, 1907 os::vm_page_size(), 1908 HeapRegion::GrainBytes, 1909 CMBitMap::mark_distance(), 1910 mtGC); 1911 1912 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size)); 1913 G1RegionToSpaceMapper* next_bitmap_storage = 1914 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs, 1915 os::vm_page_size(), 1916 HeapRegion::GrainBytes, 1917 CMBitMap::mark_distance(), 1918 mtGC); 1919 1920 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1921 g1_barrier_set()->initialize(cardtable_storage); 1922 // Do later initialization work for concurrent refinement. 1923 _cg1r->init(card_counts_storage); 1924 1925 // 6843694 - ensure that the maximum region index can fit 1926 // in the remembered set structures. 1927 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1928 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1929 1930 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1931 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1932 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1933 "too many cards per region"); 1934 1935 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1936 1937 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage); 1938 1939 _g1h = this; 1940 1941 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes); 1942 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes); 1943 1944 // Create the ConcurrentMark data structure and thread. 1945 // (Must do this late, so that "max_regions" is defined.) 1946 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1947 if (_cm == NULL || !_cm->completed_initialization()) { 1948 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 1949 return JNI_ENOMEM; 1950 } 1951 _cmThread = _cm->cmThread(); 1952 1953 // Initialize the from_card cache structure of HeapRegionRemSet. 1954 HeapRegionRemSet::init_heap(max_regions()); 1955 1956 // Now expand into the initial heap size. 1957 if (!expand(init_byte_size)) { 1958 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1959 return JNI_ENOMEM; 1960 } 1961 1962 // Perform any initialization actions delegated to the policy. 1963 g1_policy()->init(); 1964 1965 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 1966 SATB_Q_FL_lock, 1967 G1SATBProcessCompletedThreshold, 1968 Shared_SATB_Q_lock); 1969 1970 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 1971 DirtyCardQ_CBL_mon, 1972 DirtyCardQ_FL_lock, 1973 concurrent_g1_refine()->yellow_zone(), 1974 concurrent_g1_refine()->red_zone(), 1975 Shared_DirtyCardQ_lock); 1976 1977 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 1978 DirtyCardQ_CBL_mon, 1979 DirtyCardQ_FL_lock, 1980 -1, // never trigger processing 1981 -1, // no limit on length 1982 Shared_DirtyCardQ_lock, 1983 &JavaThread::dirty_card_queue_set()); 1984 1985 // Initialize the card queue set used to hold cards containing 1986 // references into the collection set. 1987 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 1988 DirtyCardQ_CBL_mon, 1989 DirtyCardQ_FL_lock, 1990 -1, // never trigger processing 1991 -1, // no limit on length 1992 Shared_DirtyCardQ_lock, 1993 &JavaThread::dirty_card_queue_set()); 1994 1995 // Here we allocate the dummy HeapRegion that is required by the 1996 // G1AllocRegion class. 1997 HeapRegion* dummy_region = _hrm.get_dummy_region(); 1998 1999 // We'll re-use the same region whether the alloc region will 2000 // require BOT updates or not and, if it doesn't, then a non-young 2001 // region will complain that it cannot support allocations without 2002 // BOT updates. So we'll tag the dummy region as eden to avoid that. 2003 dummy_region->set_eden(); 2004 // Make sure it's full. 2005 dummy_region->set_top(dummy_region->end()); 2006 G1AllocRegion::setup(this, dummy_region); 2007 2008 _allocator->init_mutator_alloc_region(); 2009 2010 // Do create of the monitoring and management support so that 2011 // values in the heap have been properly initialized. 2012 _g1mm = new G1MonitoringSupport(this); 2013 2014 G1StringDedup::initialize(); 2015 2016 return JNI_OK; 2017 } 2018 2019 void G1CollectedHeap::stop() { 2020 // Stop all concurrent threads. We do this to make sure these threads 2021 // do not continue to execute and access resources (e.g. gclog_or_tty) 2022 // that are destroyed during shutdown. 2023 _cg1r->stop(); 2024 _cmThread->stop(); 2025 if (G1StringDedup::is_enabled()) { 2026 G1StringDedup::stop(); 2027 } 2028 } 2029 2030 void G1CollectedHeap::clear_humongous_is_live_table() { 2031 guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true"); 2032 _humongous_is_live.clear(); 2033 } 2034 2035 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2036 return HeapRegion::max_region_size(); 2037 } 2038 2039 void G1CollectedHeap::ref_processing_init() { 2040 // Reference processing in G1 currently works as follows: 2041 // 2042 // * There are two reference processor instances. One is 2043 // used to record and process discovered references 2044 // during concurrent marking; the other is used to 2045 // record and process references during STW pauses 2046 // (both full and incremental). 2047 // * Both ref processors need to 'span' the entire heap as 2048 // the regions in the collection set may be dotted around. 2049 // 2050 // * For the concurrent marking ref processor: 2051 // * Reference discovery is enabled at initial marking. 2052 // * Reference discovery is disabled and the discovered 2053 // references processed etc during remarking. 2054 // * Reference discovery is MT (see below). 2055 // * Reference discovery requires a barrier (see below). 2056 // * Reference processing may or may not be MT 2057 // (depending on the value of ParallelRefProcEnabled 2058 // and ParallelGCThreads). 2059 // * A full GC disables reference discovery by the CM 2060 // ref processor and abandons any entries on it's 2061 // discovered lists. 2062 // 2063 // * For the STW processor: 2064 // * Non MT discovery is enabled at the start of a full GC. 2065 // * Processing and enqueueing during a full GC is non-MT. 2066 // * During a full GC, references are processed after marking. 2067 // 2068 // * Discovery (may or may not be MT) is enabled at the start 2069 // of an incremental evacuation pause. 2070 // * References are processed near the end of a STW evacuation pause. 2071 // * For both types of GC: 2072 // * Discovery is atomic - i.e. not concurrent. 2073 // * Reference discovery will not need a barrier. 2074 2075 SharedHeap::ref_processing_init(); 2076 MemRegion mr = reserved_region(); 2077 2078 // Concurrent Mark ref processor 2079 _ref_processor_cm = 2080 new ReferenceProcessor(mr, // span 2081 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2082 // mt processing 2083 (int) ParallelGCThreads, 2084 // degree of mt processing 2085 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2086 // mt discovery 2087 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2088 // degree of mt discovery 2089 false, 2090 // Reference discovery is not atomic 2091 &_is_alive_closure_cm); 2092 // is alive closure 2093 // (for efficiency/performance) 2094 2095 // STW ref processor 2096 _ref_processor_stw = 2097 new ReferenceProcessor(mr, // span 2098 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2099 // mt processing 2100 MAX2((int)ParallelGCThreads, 1), 2101 // degree of mt processing 2102 (ParallelGCThreads > 1), 2103 // mt discovery 2104 MAX2((int)ParallelGCThreads, 1), 2105 // degree of mt discovery 2106 true, 2107 // Reference discovery is atomic 2108 &_is_alive_closure_stw); 2109 // is alive closure 2110 // (for efficiency/performance) 2111 } 2112 2113 size_t G1CollectedHeap::capacity() const { 2114 return _hrm.length() * HeapRegion::GrainBytes; 2115 } 2116 2117 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2118 assert(!hr->is_continues_humongous(), "pre-condition"); 2119 hr->reset_gc_time_stamp(); 2120 if (hr->is_starts_humongous()) { 2121 uint first_index = hr->hrm_index() + 1; 2122 uint last_index = hr->last_hc_index(); 2123 for (uint i = first_index; i < last_index; i += 1) { 2124 HeapRegion* chr = region_at(i); 2125 assert(chr->is_continues_humongous(), "sanity"); 2126 chr->reset_gc_time_stamp(); 2127 } 2128 } 2129 } 2130 2131 #ifndef PRODUCT 2132 2133 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2134 private: 2135 unsigned _gc_time_stamp; 2136 bool _failures; 2137 2138 public: 2139 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2140 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2141 2142 virtual bool doHeapRegion(HeapRegion* hr) { 2143 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2144 if (_gc_time_stamp != region_gc_time_stamp) { 2145 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2146 "expected %d", HR_FORMAT_PARAMS(hr), 2147 region_gc_time_stamp, _gc_time_stamp); 2148 _failures = true; 2149 } 2150 return false; 2151 } 2152 2153 bool failures() { return _failures; } 2154 }; 2155 2156 void G1CollectedHeap::check_gc_time_stamps() { 2157 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2158 heap_region_iterate(&cl); 2159 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2160 } 2161 #endif // PRODUCT 2162 2163 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2164 DirtyCardQueue* into_cset_dcq, 2165 bool concurrent, 2166 uint worker_i) { 2167 // Clean cards in the hot card cache 2168 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2169 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2170 2171 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2172 size_t n_completed_buffers = 0; 2173 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2174 n_completed_buffers++; 2175 } 2176 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 2177 dcqs.clear_n_completed_buffers(); 2178 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2179 } 2180 2181 2182 // Computes the sum of the storage used by the various regions. 2183 size_t G1CollectedHeap::used() const { 2184 return _allocator->used(); 2185 } 2186 2187 size_t G1CollectedHeap::used_unlocked() const { 2188 return _allocator->used_unlocked(); 2189 } 2190 2191 class SumUsedClosure: public HeapRegionClosure { 2192 size_t _used; 2193 public: 2194 SumUsedClosure() : _used(0) {} 2195 bool doHeapRegion(HeapRegion* r) { 2196 if (!r->is_continues_humongous()) { 2197 _used += r->used(); 2198 } 2199 return false; 2200 } 2201 size_t result() { return _used; } 2202 }; 2203 2204 size_t G1CollectedHeap::recalculate_used() const { 2205 double recalculate_used_start = os::elapsedTime(); 2206 2207 SumUsedClosure blk; 2208 heap_region_iterate(&blk); 2209 2210 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2211 return blk.result(); 2212 } 2213 2214 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2215 switch (cause) { 2216 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2217 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2218 case GCCause::_g1_humongous_allocation: return true; 2219 case GCCause::_update_allocation_context_stats_inc: return true; 2220 case GCCause::_wb_conc_mark: return true; 2221 default: return false; 2222 } 2223 } 2224 2225 #ifndef PRODUCT 2226 void G1CollectedHeap::allocate_dummy_regions() { 2227 // Let's fill up most of the region 2228 size_t word_size = HeapRegion::GrainWords - 1024; 2229 // And as a result the region we'll allocate will be humongous. 2230 guarantee(is_humongous(word_size), "sanity"); 2231 2232 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2233 // Let's use the existing mechanism for the allocation 2234 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2235 AllocationContext::system()); 2236 if (dummy_obj != NULL) { 2237 MemRegion mr(dummy_obj, word_size); 2238 CollectedHeap::fill_with_object(mr); 2239 } else { 2240 // If we can't allocate once, we probably cannot allocate 2241 // again. Let's get out of the loop. 2242 break; 2243 } 2244 } 2245 } 2246 #endif // !PRODUCT 2247 2248 void G1CollectedHeap::increment_old_marking_cycles_started() { 2249 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2250 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2251 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2252 _old_marking_cycles_started, _old_marking_cycles_completed)); 2253 2254 _old_marking_cycles_started++; 2255 } 2256 2257 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2258 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2259 2260 // We assume that if concurrent == true, then the caller is a 2261 // concurrent thread that was joined the Suspendible Thread 2262 // Set. If there's ever a cheap way to check this, we should add an 2263 // assert here. 2264 2265 // Given that this method is called at the end of a Full GC or of a 2266 // concurrent cycle, and those can be nested (i.e., a Full GC can 2267 // interrupt a concurrent cycle), the number of full collections 2268 // completed should be either one (in the case where there was no 2269 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2270 // behind the number of full collections started. 2271 2272 // This is the case for the inner caller, i.e. a Full GC. 2273 assert(concurrent || 2274 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2275 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2276 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2277 "is inconsistent with _old_marking_cycles_completed = %u", 2278 _old_marking_cycles_started, _old_marking_cycles_completed)); 2279 2280 // This is the case for the outer caller, i.e. the concurrent cycle. 2281 assert(!concurrent || 2282 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2283 err_msg("for outer caller (concurrent cycle): " 2284 "_old_marking_cycles_started = %u " 2285 "is inconsistent with _old_marking_cycles_completed = %u", 2286 _old_marking_cycles_started, _old_marking_cycles_completed)); 2287 2288 _old_marking_cycles_completed += 1; 2289 2290 // We need to clear the "in_progress" flag in the CM thread before 2291 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2292 // is set) so that if a waiter requests another System.gc() it doesn't 2293 // incorrectly see that a marking cycle is still in progress. 2294 if (concurrent) { 2295 _cmThread->clear_in_progress(); 2296 } 2297 2298 // This notify_all() will ensure that a thread that called 2299 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2300 // and it's waiting for a full GC to finish will be woken up. It is 2301 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2302 FullGCCount_lock->notify_all(); 2303 } 2304 2305 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2306 _concurrent_cycle_started = true; 2307 _gc_timer_cm->register_gc_start(start_time); 2308 2309 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2310 trace_heap_before_gc(_gc_tracer_cm); 2311 } 2312 2313 void G1CollectedHeap::register_concurrent_cycle_end() { 2314 if (_concurrent_cycle_started) { 2315 if (_cm->has_aborted()) { 2316 _gc_tracer_cm->report_concurrent_mode_failure(); 2317 } 2318 2319 _gc_timer_cm->register_gc_end(); 2320 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2321 2322 // Clear state variables to prepare for the next concurrent cycle. 2323 _concurrent_cycle_started = false; 2324 _heap_summary_sent = false; 2325 } 2326 } 2327 2328 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2329 if (_concurrent_cycle_started) { 2330 // This function can be called when: 2331 // the cleanup pause is run 2332 // the concurrent cycle is aborted before the cleanup pause. 2333 // the concurrent cycle is aborted after the cleanup pause, 2334 // but before the concurrent cycle end has been registered. 2335 // Make sure that we only send the heap information once. 2336 if (!_heap_summary_sent) { 2337 trace_heap_after_gc(_gc_tracer_cm); 2338 _heap_summary_sent = true; 2339 } 2340 } 2341 } 2342 2343 G1YCType G1CollectedHeap::yc_type() { 2344 bool is_young = g1_policy()->gcs_are_young(); 2345 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2346 bool is_during_mark = mark_in_progress(); 2347 2348 if (is_initial_mark) { 2349 return InitialMark; 2350 } else if (is_during_mark) { 2351 return DuringMark; 2352 } else if (is_young) { 2353 return Normal; 2354 } else { 2355 return Mixed; 2356 } 2357 } 2358 2359 void G1CollectedHeap::collect(GCCause::Cause cause) { 2360 assert_heap_not_locked(); 2361 2362 uint gc_count_before; 2363 uint old_marking_count_before; 2364 uint full_gc_count_before; 2365 bool retry_gc; 2366 2367 do { 2368 retry_gc = false; 2369 2370 { 2371 MutexLocker ml(Heap_lock); 2372 2373 // Read the GC count while holding the Heap_lock 2374 gc_count_before = total_collections(); 2375 full_gc_count_before = total_full_collections(); 2376 old_marking_count_before = _old_marking_cycles_started; 2377 } 2378 2379 if (should_do_concurrent_full_gc(cause)) { 2380 // Schedule an initial-mark evacuation pause that will start a 2381 // concurrent cycle. We're setting word_size to 0 which means that 2382 // we are not requesting a post-GC allocation. 2383 VM_G1IncCollectionPause op(gc_count_before, 2384 0, /* word_size */ 2385 true, /* should_initiate_conc_mark */ 2386 g1_policy()->max_pause_time_ms(), 2387 cause); 2388 op.set_allocation_context(AllocationContext::current()); 2389 2390 VMThread::execute(&op); 2391 if (!op.pause_succeeded()) { 2392 if (old_marking_count_before == _old_marking_cycles_started) { 2393 retry_gc = op.should_retry_gc(); 2394 } else { 2395 // A Full GC happened while we were trying to schedule the 2396 // initial-mark GC. No point in starting a new cycle given 2397 // that the whole heap was collected anyway. 2398 } 2399 2400 if (retry_gc) { 2401 if (GC_locker::is_active_and_needs_gc()) { 2402 GC_locker::stall_until_clear(); 2403 } 2404 } 2405 } 2406 } else { 2407 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2408 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2409 2410 // Schedule a standard evacuation pause. We're setting word_size 2411 // to 0 which means that we are not requesting a post-GC allocation. 2412 VM_G1IncCollectionPause op(gc_count_before, 2413 0, /* word_size */ 2414 false, /* should_initiate_conc_mark */ 2415 g1_policy()->max_pause_time_ms(), 2416 cause); 2417 VMThread::execute(&op); 2418 } else { 2419 // Schedule a Full GC. 2420 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2421 VMThread::execute(&op); 2422 } 2423 } 2424 } while (retry_gc); 2425 } 2426 2427 bool G1CollectedHeap::is_in(const void* p) const { 2428 if (_hrm.reserved().contains(p)) { 2429 // Given that we know that p is in the reserved space, 2430 // heap_region_containing_raw() should successfully 2431 // return the containing region. 2432 HeapRegion* hr = heap_region_containing_raw(p); 2433 return hr->is_in(p); 2434 } else { 2435 return false; 2436 } 2437 } 2438 2439 #ifdef ASSERT 2440 bool G1CollectedHeap::is_in_exact(const void* p) const { 2441 bool contains = reserved_region().contains(p); 2442 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2443 if (contains && available) { 2444 return true; 2445 } else { 2446 return false; 2447 } 2448 } 2449 #endif 2450 2451 // Iteration functions. 2452 2453 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2454 2455 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2456 ExtendedOopClosure* _cl; 2457 public: 2458 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2459 bool doHeapRegion(HeapRegion* r) { 2460 if (!r->is_continues_humongous()) { 2461 r->oop_iterate(_cl); 2462 } 2463 return false; 2464 } 2465 }; 2466 2467 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 2468 IterateOopClosureRegionClosure blk(cl); 2469 heap_region_iterate(&blk); 2470 } 2471 2472 // Iterates an ObjectClosure over all objects within a HeapRegion. 2473 2474 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2475 ObjectClosure* _cl; 2476 public: 2477 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2478 bool doHeapRegion(HeapRegion* r) { 2479 if (!r->is_continues_humongous()) { 2480 r->object_iterate(_cl); 2481 } 2482 return false; 2483 } 2484 }; 2485 2486 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2487 IterateObjectClosureRegionClosure blk(cl); 2488 heap_region_iterate(&blk); 2489 } 2490 2491 // Calls a SpaceClosure on a HeapRegion. 2492 2493 class SpaceClosureRegionClosure: public HeapRegionClosure { 2494 SpaceClosure* _cl; 2495 public: 2496 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} 2497 bool doHeapRegion(HeapRegion* r) { 2498 _cl->do_space(r); 2499 return false; 2500 } 2501 }; 2502 2503 void G1CollectedHeap::space_iterate(SpaceClosure* cl) { 2504 SpaceClosureRegionClosure blk(cl); 2505 heap_region_iterate(&blk); 2506 } 2507 2508 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2509 _hrm.iterate(cl); 2510 } 2511 2512 void 2513 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, 2514 uint worker_id, 2515 HeapRegionClaimer *hrclaimer, 2516 bool concurrent) const { 2517 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); 2518 } 2519 2520 // Clear the cached CSet starting regions and (more importantly) 2521 // the time stamps. Called when we reset the GC time stamp. 2522 void G1CollectedHeap::clear_cset_start_regions() { 2523 assert(_worker_cset_start_region != NULL, "sanity"); 2524 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2525 2526 int n_queues = MAX2((int)ParallelGCThreads, 1); 2527 for (int i = 0; i < n_queues; i++) { 2528 _worker_cset_start_region[i] = NULL; 2529 _worker_cset_start_region_time_stamp[i] = 0; 2530 } 2531 } 2532 2533 // Given the id of a worker, obtain or calculate a suitable 2534 // starting region for iterating over the current collection set. 2535 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2536 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2537 2538 HeapRegion* result = NULL; 2539 unsigned gc_time_stamp = get_gc_time_stamp(); 2540 2541 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2542 // Cached starting region for current worker was set 2543 // during the current pause - so it's valid. 2544 // Note: the cached starting heap region may be NULL 2545 // (when the collection set is empty). 2546 result = _worker_cset_start_region[worker_i]; 2547 assert(result == NULL || result->in_collection_set(), "sanity"); 2548 return result; 2549 } 2550 2551 // The cached entry was not valid so let's calculate 2552 // a suitable starting heap region for this worker. 2553 2554 // We want the parallel threads to start their collection 2555 // set iteration at different collection set regions to 2556 // avoid contention. 2557 // If we have: 2558 // n collection set regions 2559 // p threads 2560 // Then thread t will start at region floor ((t * n) / p) 2561 2562 result = g1_policy()->collection_set(); 2563 uint cs_size = g1_policy()->cset_region_length(); 2564 uint active_workers = workers()->active_workers(); 2565 assert(UseDynamicNumberOfGCThreads || 2566 active_workers == workers()->total_workers(), 2567 "Unless dynamic should use total workers"); 2568 2569 uint end_ind = (cs_size * worker_i) / active_workers; 2570 uint start_ind = 0; 2571 2572 if (worker_i > 0 && 2573 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2574 // Previous workers starting region is valid 2575 // so let's iterate from there 2576 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2577 result = _worker_cset_start_region[worker_i - 1]; 2578 } 2579 2580 for (uint i = start_ind; i < end_ind; i++) { 2581 result = result->next_in_collection_set(); 2582 } 2583 2584 // Note: the calculated starting heap region may be NULL 2585 // (when the collection set is empty). 2586 assert(result == NULL || result->in_collection_set(), "sanity"); 2587 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2588 "should be updated only once per pause"); 2589 _worker_cset_start_region[worker_i] = result; 2590 OrderAccess::storestore(); 2591 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2592 return result; 2593 } 2594 2595 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2596 HeapRegion* r = g1_policy()->collection_set(); 2597 while (r != NULL) { 2598 HeapRegion* next = r->next_in_collection_set(); 2599 if (cl->doHeapRegion(r)) { 2600 cl->incomplete(); 2601 return; 2602 } 2603 r = next; 2604 } 2605 } 2606 2607 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2608 HeapRegionClosure *cl) { 2609 if (r == NULL) { 2610 // The CSet is empty so there's nothing to do. 2611 return; 2612 } 2613 2614 assert(r->in_collection_set(), 2615 "Start region must be a member of the collection set."); 2616 HeapRegion* cur = r; 2617 while (cur != NULL) { 2618 HeapRegion* next = cur->next_in_collection_set(); 2619 if (cl->doHeapRegion(cur) && false) { 2620 cl->incomplete(); 2621 return; 2622 } 2623 cur = next; 2624 } 2625 cur = g1_policy()->collection_set(); 2626 while (cur != r) { 2627 HeapRegion* next = cur->next_in_collection_set(); 2628 if (cl->doHeapRegion(cur) && false) { 2629 cl->incomplete(); 2630 return; 2631 } 2632 cur = next; 2633 } 2634 } 2635 2636 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2637 HeapRegion* result = _hrm.next_region_in_heap(from); 2638 while (result != NULL && result->is_humongous()) { 2639 result = _hrm.next_region_in_heap(result); 2640 } 2641 return result; 2642 } 2643 2644 Space* G1CollectedHeap::space_containing(const void* addr) const { 2645 return heap_region_containing(addr); 2646 } 2647 2648 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2649 Space* sp = space_containing(addr); 2650 return sp->block_start(addr); 2651 } 2652 2653 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2654 Space* sp = space_containing(addr); 2655 return sp->block_size(addr); 2656 } 2657 2658 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2659 Space* sp = space_containing(addr); 2660 return sp->block_is_obj(addr); 2661 } 2662 2663 bool G1CollectedHeap::supports_tlab_allocation() const { 2664 return true; 2665 } 2666 2667 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2668 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2669 } 2670 2671 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2672 return young_list()->eden_used_bytes(); 2673 } 2674 2675 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2676 // must be smaller than the humongous object limit. 2677 size_t G1CollectedHeap::max_tlab_size() const { 2678 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 2679 } 2680 2681 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2682 // Return the remaining space in the cur alloc region, but not less than 2683 // the min TLAB size. 2684 2685 // Also, this value can be at most the humongous object threshold, 2686 // since we can't allow tlabs to grow big enough to accommodate 2687 // humongous objects. 2688 2689 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get(); 2690 size_t max_tlab = max_tlab_size() * wordSize; 2691 if (hr == NULL) { 2692 return max_tlab; 2693 } else { 2694 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 2695 } 2696 } 2697 2698 size_t G1CollectedHeap::max_capacity() const { 2699 return _hrm.reserved().byte_size(); 2700 } 2701 2702 jlong G1CollectedHeap::millis_since_last_gc() { 2703 // assert(false, "NYI"); 2704 return 0; 2705 } 2706 2707 void G1CollectedHeap::prepare_for_verify() { 2708 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2709 ensure_parsability(false); 2710 } 2711 g1_rem_set()->prepare_for_verify(); 2712 } 2713 2714 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 2715 VerifyOption vo) { 2716 switch (vo) { 2717 case VerifyOption_G1UsePrevMarking: 2718 return hr->obj_allocated_since_prev_marking(obj); 2719 case VerifyOption_G1UseNextMarking: 2720 return hr->obj_allocated_since_next_marking(obj); 2721 case VerifyOption_G1UseMarkWord: 2722 return false; 2723 default: 2724 ShouldNotReachHere(); 2725 } 2726 return false; // keep some compilers happy 2727 } 2728 2729 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 2730 switch (vo) { 2731 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 2732 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 2733 case VerifyOption_G1UseMarkWord: return NULL; 2734 default: ShouldNotReachHere(); 2735 } 2736 return NULL; // keep some compilers happy 2737 } 2738 2739 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 2740 switch (vo) { 2741 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 2742 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 2743 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 2744 default: ShouldNotReachHere(); 2745 } 2746 return false; // keep some compilers happy 2747 } 2748 2749 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 2750 switch (vo) { 2751 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 2752 case VerifyOption_G1UseNextMarking: return "NTAMS"; 2753 case VerifyOption_G1UseMarkWord: return "NONE"; 2754 default: ShouldNotReachHere(); 2755 } 2756 return NULL; // keep some compilers happy 2757 } 2758 2759 class VerifyRootsClosure: public OopClosure { 2760 private: 2761 G1CollectedHeap* _g1h; 2762 VerifyOption _vo; 2763 bool _failures; 2764 public: 2765 // _vo == UsePrevMarking -> use "prev" marking information, 2766 // _vo == UseNextMarking -> use "next" marking information, 2767 // _vo == UseMarkWord -> use mark word from object header. 2768 VerifyRootsClosure(VerifyOption vo) : 2769 _g1h(G1CollectedHeap::heap()), 2770 _vo(vo), 2771 _failures(false) { } 2772 2773 bool failures() { return _failures; } 2774 2775 template <class T> void do_oop_nv(T* p) { 2776 T heap_oop = oopDesc::load_heap_oop(p); 2777 if (!oopDesc::is_null(heap_oop)) { 2778 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2779 if (_g1h->is_obj_dead_cond(obj, _vo)) { 2780 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 2781 "points to dead obj "PTR_FORMAT, p, (void*) obj); 2782 if (_vo == VerifyOption_G1UseMarkWord) { 2783 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 2784 } 2785 obj->print_on(gclog_or_tty); 2786 _failures = true; 2787 } 2788 } 2789 } 2790 2791 void do_oop(oop* p) { do_oop_nv(p); } 2792 void do_oop(narrowOop* p) { do_oop_nv(p); } 2793 }; 2794 2795 class G1VerifyCodeRootOopClosure: public OopClosure { 2796 G1CollectedHeap* _g1h; 2797 OopClosure* _root_cl; 2798 nmethod* _nm; 2799 VerifyOption _vo; 2800 bool _failures; 2801 2802 template <class T> void do_oop_work(T* p) { 2803 // First verify that this root is live 2804 _root_cl->do_oop(p); 2805 2806 if (!G1VerifyHeapRegionCodeRoots) { 2807 // We're not verifying the code roots attached to heap region. 2808 return; 2809 } 2810 2811 // Don't check the code roots during marking verification in a full GC 2812 if (_vo == VerifyOption_G1UseMarkWord) { 2813 return; 2814 } 2815 2816 // Now verify that the current nmethod (which contains p) is 2817 // in the code root list of the heap region containing the 2818 // object referenced by p. 2819 2820 T heap_oop = oopDesc::load_heap_oop(p); 2821 if (!oopDesc::is_null(heap_oop)) { 2822 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2823 2824 // Now fetch the region containing the object 2825 HeapRegion* hr = _g1h->heap_region_containing(obj); 2826 HeapRegionRemSet* hrrs = hr->rem_set(); 2827 // Verify that the strong code root list for this region 2828 // contains the nmethod 2829 if (!hrrs->strong_code_roots_list_contains(_nm)) { 2830 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " 2831 "from nmethod "PTR_FORMAT" not in strong " 2832 "code roots for region ["PTR_FORMAT","PTR_FORMAT")", 2833 p, _nm, hr->bottom(), hr->end()); 2834 _failures = true; 2835 } 2836 } 2837 } 2838 2839 public: 2840 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 2841 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 2842 2843 void do_oop(oop* p) { do_oop_work(p); } 2844 void do_oop(narrowOop* p) { do_oop_work(p); } 2845 2846 void set_nmethod(nmethod* nm) { _nm = nm; } 2847 bool failures() { return _failures; } 2848 }; 2849 2850 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 2851 G1VerifyCodeRootOopClosure* _oop_cl; 2852 2853 public: 2854 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 2855 _oop_cl(oop_cl) {} 2856 2857 void do_code_blob(CodeBlob* cb) { 2858 nmethod* nm = cb->as_nmethod_or_null(); 2859 if (nm != NULL) { 2860 _oop_cl->set_nmethod(nm); 2861 nm->oops_do(_oop_cl); 2862 } 2863 } 2864 }; 2865 2866 class YoungRefCounterClosure : public OopClosure { 2867 G1CollectedHeap* _g1h; 2868 int _count; 2869 public: 2870 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 2871 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 2872 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 2873 2874 int count() { return _count; } 2875 void reset_count() { _count = 0; }; 2876 }; 2877 2878 class VerifyKlassClosure: public KlassClosure { 2879 YoungRefCounterClosure _young_ref_counter_closure; 2880 OopClosure *_oop_closure; 2881 public: 2882 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 2883 void do_klass(Klass* k) { 2884 k->oops_do(_oop_closure); 2885 2886 _young_ref_counter_closure.reset_count(); 2887 k->oops_do(&_young_ref_counter_closure); 2888 if (_young_ref_counter_closure.count() > 0) { 2889 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k)); 2890 } 2891 } 2892 }; 2893 2894 class VerifyLivenessOopClosure: public OopClosure { 2895 G1CollectedHeap* _g1h; 2896 VerifyOption _vo; 2897 public: 2898 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 2899 _g1h(g1h), _vo(vo) 2900 { } 2901 void do_oop(narrowOop *p) { do_oop_work(p); } 2902 void do_oop( oop *p) { do_oop_work(p); } 2903 2904 template <class T> void do_oop_work(T *p) { 2905 oop obj = oopDesc::load_decode_heap_oop(p); 2906 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 2907 "Dead object referenced by a not dead object"); 2908 } 2909 }; 2910 2911 class VerifyObjsInRegionClosure: public ObjectClosure { 2912 private: 2913 G1CollectedHeap* _g1h; 2914 size_t _live_bytes; 2915 HeapRegion *_hr; 2916 VerifyOption _vo; 2917 public: 2918 // _vo == UsePrevMarking -> use "prev" marking information, 2919 // _vo == UseNextMarking -> use "next" marking information, 2920 // _vo == UseMarkWord -> use mark word from object header. 2921 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 2922 : _live_bytes(0), _hr(hr), _vo(vo) { 2923 _g1h = G1CollectedHeap::heap(); 2924 } 2925 void do_object(oop o) { 2926 VerifyLivenessOopClosure isLive(_g1h, _vo); 2927 assert(o != NULL, "Huh?"); 2928 if (!_g1h->is_obj_dead_cond(o, _vo)) { 2929 // If the object is alive according to the mark word, 2930 // then verify that the marking information agrees. 2931 // Note we can't verify the contra-positive of the 2932 // above: if the object is dead (according to the mark 2933 // word), it may not be marked, or may have been marked 2934 // but has since became dead, or may have been allocated 2935 // since the last marking. 2936 if (_vo == VerifyOption_G1UseMarkWord) { 2937 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 2938 } 2939 2940 o->oop_iterate_no_header(&isLive); 2941 if (!_hr->obj_allocated_since_prev_marking(o)) { 2942 size_t obj_size = o->size(); // Make sure we don't overflow 2943 _live_bytes += (obj_size * HeapWordSize); 2944 } 2945 } 2946 } 2947 size_t live_bytes() { return _live_bytes; } 2948 }; 2949 2950 class PrintObjsInRegionClosure : public ObjectClosure { 2951 HeapRegion *_hr; 2952 G1CollectedHeap *_g1; 2953 public: 2954 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 2955 _g1 = G1CollectedHeap::heap(); 2956 }; 2957 2958 void do_object(oop o) { 2959 if (o != NULL) { 2960 HeapWord *start = (HeapWord *) o; 2961 size_t word_sz = o->size(); 2962 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 2963 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 2964 (void*) o, word_sz, 2965 _g1->isMarkedPrev(o), 2966 _g1->isMarkedNext(o), 2967 _hr->obj_allocated_since_prev_marking(o)); 2968 HeapWord *end = start + word_sz; 2969 HeapWord *cur; 2970 int *val; 2971 for (cur = start; cur < end; cur++) { 2972 val = (int *) cur; 2973 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val); 2974 } 2975 } 2976 } 2977 }; 2978 2979 class VerifyRegionClosure: public HeapRegionClosure { 2980 private: 2981 bool _par; 2982 VerifyOption _vo; 2983 bool _failures; 2984 public: 2985 // _vo == UsePrevMarking -> use "prev" marking information, 2986 // _vo == UseNextMarking -> use "next" marking information, 2987 // _vo == UseMarkWord -> use mark word from object header. 2988 VerifyRegionClosure(bool par, VerifyOption vo) 2989 : _par(par), 2990 _vo(vo), 2991 _failures(false) {} 2992 2993 bool failures() { 2994 return _failures; 2995 } 2996 2997 bool doHeapRegion(HeapRegion* r) { 2998 if (!r->is_continues_humongous()) { 2999 bool failures = false; 3000 r->verify(_vo, &failures); 3001 if (failures) { 3002 _failures = true; 3003 } else { 3004 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3005 r->object_iterate(¬_dead_yet_cl); 3006 if (_vo != VerifyOption_G1UseNextMarking) { 3007 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3008 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 3009 "max_live_bytes "SIZE_FORMAT" " 3010 "< calculated "SIZE_FORMAT, 3011 r->bottom(), r->end(), 3012 r->max_live_bytes(), 3013 not_dead_yet_cl.live_bytes()); 3014 _failures = true; 3015 } 3016 } else { 3017 // When vo == UseNextMarking we cannot currently do a sanity 3018 // check on the live bytes as the calculation has not been 3019 // finalized yet. 3020 } 3021 } 3022 } 3023 return false; // stop the region iteration if we hit a failure 3024 } 3025 }; 3026 3027 // This is the task used for parallel verification of the heap regions 3028 3029 class G1ParVerifyTask: public AbstractGangTask { 3030 private: 3031 G1CollectedHeap* _g1h; 3032 VerifyOption _vo; 3033 bool _failures; 3034 HeapRegionClaimer _hrclaimer; 3035 3036 public: 3037 // _vo == UsePrevMarking -> use "prev" marking information, 3038 // _vo == UseNextMarking -> use "next" marking information, 3039 // _vo == UseMarkWord -> use mark word from object header. 3040 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3041 AbstractGangTask("Parallel verify task"), 3042 _g1h(g1h), 3043 _vo(vo), 3044 _failures(false), 3045 _hrclaimer(g1h->workers()->active_workers()) {} 3046 3047 bool failures() { 3048 return _failures; 3049 } 3050 3051 void work(uint worker_id) { 3052 HandleMark hm; 3053 VerifyRegionClosure blk(true, _vo); 3054 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer); 3055 if (blk.failures()) { 3056 _failures = true; 3057 } 3058 } 3059 }; 3060 3061 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3062 if (SafepointSynchronize::is_at_safepoint()) { 3063 assert(Thread::current()->is_VM_thread(), 3064 "Expected to be executed serially by the VM thread at this point"); 3065 3066 if (!silent) { gclog_or_tty->print("Roots "); } 3067 VerifyRootsClosure rootsCl(vo); 3068 VerifyKlassClosure klassCl(this, &rootsCl); 3069 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3070 3071 // We apply the relevant closures to all the oops in the 3072 // system dictionary, class loader data graph, the string table 3073 // and the nmethods in the code cache. 3074 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3075 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3076 3077 { 3078 G1RootProcessor root_processor(this); 3079 root_processor.process_all_roots(&rootsCl, 3080 &cldCl, 3081 &blobsCl); 3082 } 3083 3084 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3085 3086 if (vo != VerifyOption_G1UseMarkWord) { 3087 // If we're verifying during a full GC then the region sets 3088 // will have been torn down at the start of the GC. Therefore 3089 // verifying the region sets will fail. So we only verify 3090 // the region sets when not in a full GC. 3091 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3092 verify_region_sets(); 3093 } 3094 3095 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3096 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3097 3098 G1ParVerifyTask task(this, vo); 3099 assert(UseDynamicNumberOfGCThreads || 3100 workers()->active_workers() == workers()->total_workers(), 3101 "If not dynamic should be using all the workers"); 3102 int n_workers = workers()->active_workers(); 3103 set_par_threads(n_workers); 3104 workers()->run_task(&task); 3105 set_par_threads(0); 3106 if (task.failures()) { 3107 failures = true; 3108 } 3109 3110 } else { 3111 VerifyRegionClosure blk(false, vo); 3112 heap_region_iterate(&blk); 3113 if (blk.failures()) { 3114 failures = true; 3115 } 3116 } 3117 3118 if (G1StringDedup::is_enabled()) { 3119 if (!silent) gclog_or_tty->print("StrDedup "); 3120 G1StringDedup::verify(); 3121 } 3122 3123 if (failures) { 3124 gclog_or_tty->print_cr("Heap:"); 3125 // It helps to have the per-region information in the output to 3126 // help us track down what went wrong. This is why we call 3127 // print_extended_on() instead of print_on(). 3128 print_extended_on(gclog_or_tty); 3129 gclog_or_tty->cr(); 3130 #ifndef PRODUCT 3131 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 3132 concurrent_mark()->print_reachable("at-verification-failure", 3133 vo, false /* all */); 3134 } 3135 #endif 3136 gclog_or_tty->flush(); 3137 } 3138 guarantee(!failures, "there should not have been any failures"); 3139 } else { 3140 if (!silent) { 3141 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3142 if (G1StringDedup::is_enabled()) { 3143 gclog_or_tty->print(", StrDedup"); 3144 } 3145 gclog_or_tty->print(") "); 3146 } 3147 } 3148 } 3149 3150 void G1CollectedHeap::verify(bool silent) { 3151 verify(silent, VerifyOption_G1UsePrevMarking); 3152 } 3153 3154 double G1CollectedHeap::verify(bool guard, const char* msg) { 3155 double verify_time_ms = 0.0; 3156 3157 if (guard && total_collections() >= VerifyGCStartAt) { 3158 double verify_start = os::elapsedTime(); 3159 HandleMark hm; // Discard invalid handles created during verification 3160 prepare_for_verify(); 3161 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3162 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3163 } 3164 3165 return verify_time_ms; 3166 } 3167 3168 void G1CollectedHeap::verify_before_gc() { 3169 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3170 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3171 } 3172 3173 void G1CollectedHeap::verify_after_gc() { 3174 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3175 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3176 } 3177 3178 class PrintRegionClosure: public HeapRegionClosure { 3179 outputStream* _st; 3180 public: 3181 PrintRegionClosure(outputStream* st) : _st(st) {} 3182 bool doHeapRegion(HeapRegion* r) { 3183 r->print_on(_st); 3184 return false; 3185 } 3186 }; 3187 3188 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3189 const HeapRegion* hr, 3190 const VerifyOption vo) const { 3191 switch (vo) { 3192 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3193 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3194 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3195 default: ShouldNotReachHere(); 3196 } 3197 return false; // keep some compilers happy 3198 } 3199 3200 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3201 const VerifyOption vo) const { 3202 switch (vo) { 3203 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3204 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3205 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3206 default: ShouldNotReachHere(); 3207 } 3208 return false; // keep some compilers happy 3209 } 3210 3211 void G1CollectedHeap::print_on(outputStream* st) const { 3212 st->print(" %-20s", "garbage-first heap"); 3213 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3214 capacity()/K, used_unlocked()/K); 3215 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3216 _hrm.reserved().start(), 3217 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords, 3218 _hrm.reserved().end()); 3219 st->cr(); 3220 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3221 uint young_regions = _young_list->length(); 3222 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3223 (size_t) young_regions * HeapRegion::GrainBytes / K); 3224 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3225 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3226 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3227 st->cr(); 3228 MetaspaceAux::print_on(st); 3229 } 3230 3231 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3232 print_on(st); 3233 3234 // Print the per-region information. 3235 st->cr(); 3236 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3237 "HS=humongous(starts), HC=humongous(continues), " 3238 "CS=collection set, F=free, TS=gc time stamp, " 3239 "PTAMS=previous top-at-mark-start, " 3240 "NTAMS=next top-at-mark-start)"); 3241 PrintRegionClosure blk(st); 3242 heap_region_iterate(&blk); 3243 } 3244 3245 void G1CollectedHeap::print_on_error(outputStream* st) const { 3246 this->CollectedHeap::print_on_error(st); 3247 3248 if (_cm != NULL) { 3249 st->cr(); 3250 _cm->print_on_error(st); 3251 } 3252 } 3253 3254 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3255 workers()->print_worker_threads_on(st); 3256 _cmThread->print_on(st); 3257 st->cr(); 3258 _cm->print_worker_threads_on(st); 3259 _cg1r->print_worker_threads_on(st); 3260 if (G1StringDedup::is_enabled()) { 3261 G1StringDedup::print_worker_threads_on(st); 3262 } 3263 } 3264 3265 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3266 workers()->threads_do(tc); 3267 tc->do_thread(_cmThread); 3268 _cg1r->threads_do(tc); 3269 if (G1StringDedup::is_enabled()) { 3270 G1StringDedup::threads_do(tc); 3271 } 3272 } 3273 3274 void G1CollectedHeap::print_tracing_info() const { 3275 // We'll overload this to mean "trace GC pause statistics." 3276 if (TraceYoungGenTime || TraceOldGenTime) { 3277 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3278 // to that. 3279 g1_policy()->print_tracing_info(); 3280 } 3281 if (G1SummarizeRSetStats) { 3282 g1_rem_set()->print_summary_info(); 3283 } 3284 if (G1SummarizeConcMark) { 3285 concurrent_mark()->print_summary_info(); 3286 } 3287 g1_policy()->print_yg_surv_rate_info(); 3288 } 3289 3290 #ifndef PRODUCT 3291 // Helpful for debugging RSet issues. 3292 3293 class PrintRSetsClosure : public HeapRegionClosure { 3294 private: 3295 const char* _msg; 3296 size_t _occupied_sum; 3297 3298 public: 3299 bool doHeapRegion(HeapRegion* r) { 3300 HeapRegionRemSet* hrrs = r->rem_set(); 3301 size_t occupied = hrrs->occupied(); 3302 _occupied_sum += occupied; 3303 3304 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3305 HR_FORMAT_PARAMS(r)); 3306 if (occupied == 0) { 3307 gclog_or_tty->print_cr(" RSet is empty"); 3308 } else { 3309 hrrs->print(); 3310 } 3311 gclog_or_tty->print_cr("----------"); 3312 return false; 3313 } 3314 3315 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3316 gclog_or_tty->cr(); 3317 gclog_or_tty->print_cr("========================================"); 3318 gclog_or_tty->print_cr("%s", msg); 3319 gclog_or_tty->cr(); 3320 } 3321 3322 ~PrintRSetsClosure() { 3323 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3324 gclog_or_tty->print_cr("========================================"); 3325 gclog_or_tty->cr(); 3326 } 3327 }; 3328 3329 void G1CollectedHeap::print_cset_rsets() { 3330 PrintRSetsClosure cl("Printing CSet RSets"); 3331 collection_set_iterate(&cl); 3332 } 3333 3334 void G1CollectedHeap::print_all_rsets() { 3335 PrintRSetsClosure cl("Printing All RSets");; 3336 heap_region_iterate(&cl); 3337 } 3338 #endif // PRODUCT 3339 3340 G1CollectedHeap* G1CollectedHeap::heap() { 3341 return _g1h; 3342 } 3343 3344 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3345 // always_do_update_barrier = false; 3346 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3347 // Fill TLAB's and such 3348 accumulate_statistics_all_tlabs(); 3349 ensure_parsability(true); 3350 3351 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3352 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3353 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3354 } 3355 } 3356 3357 void G1CollectedHeap::gc_epilogue(bool full) { 3358 3359 if (G1SummarizeRSetStats && 3360 (G1SummarizeRSetStatsPeriod > 0) && 3361 // we are at the end of the GC. Total collections has already been increased. 3362 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3363 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3364 } 3365 3366 // FIXME: what is this about? 3367 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3368 // is set. 3369 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3370 "derived pointer present")); 3371 // always_do_update_barrier = true; 3372 3373 resize_all_tlabs(); 3374 allocation_context_stats().update(full); 3375 3376 // We have just completed a GC. Update the soft reference 3377 // policy with the new heap occupancy 3378 Universe::update_heap_info_at_gc(); 3379 } 3380 3381 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3382 uint gc_count_before, 3383 bool* succeeded, 3384 GCCause::Cause gc_cause) { 3385 assert_heap_not_locked_and_not_at_safepoint(); 3386 g1_policy()->record_stop_world_start(); 3387 VM_G1IncCollectionPause op(gc_count_before, 3388 word_size, 3389 false, /* should_initiate_conc_mark */ 3390 g1_policy()->max_pause_time_ms(), 3391 gc_cause); 3392 3393 op.set_allocation_context(AllocationContext::current()); 3394 VMThread::execute(&op); 3395 3396 HeapWord* result = op.result(); 3397 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3398 assert(result == NULL || ret_succeeded, 3399 "the result should be NULL if the VM did not succeed"); 3400 *succeeded = ret_succeeded; 3401 3402 assert_heap_not_locked(); 3403 return result; 3404 } 3405 3406 void 3407 G1CollectedHeap::doConcurrentMark() { 3408 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3409 if (!_cmThread->in_progress()) { 3410 _cmThread->set_started(); 3411 CGC_lock->notify(); 3412 } 3413 } 3414 3415 size_t G1CollectedHeap::pending_card_num() { 3416 size_t extra_cards = 0; 3417 JavaThread *curr = Threads::first(); 3418 while (curr != NULL) { 3419 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3420 extra_cards += dcq.size(); 3421 curr = curr->next(); 3422 } 3423 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3424 size_t buffer_size = dcqs.buffer_size(); 3425 size_t buffer_num = dcqs.completed_buffers_num(); 3426 3427 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3428 // in bytes - not the number of 'entries'. We need to convert 3429 // into a number of cards. 3430 return (buffer_size * buffer_num + extra_cards) / oopSize; 3431 } 3432 3433 size_t G1CollectedHeap::cards_scanned() { 3434 return g1_rem_set()->cardsScanned(); 3435 } 3436 3437 bool G1CollectedHeap::humongous_region_is_always_live(uint index) { 3438 HeapRegion* region = region_at(index); 3439 assert(region->is_starts_humongous(), "Must start a humongous object"); 3440 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty(); 3441 } 3442 3443 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3444 private: 3445 size_t _total_humongous; 3446 size_t _candidate_humongous; 3447 3448 DirtyCardQueue _dcq; 3449 3450 bool humongous_region_is_candidate(uint index) { 3451 HeapRegion* region = G1CollectedHeap::heap()->region_at(index); 3452 assert(region->is_starts_humongous(), "Must start a humongous object"); 3453 HeapRegionRemSet* const rset = region->rem_set(); 3454 bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs; 3455 return !oop(region->bottom())->is_objArray() && 3456 ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) || 3457 (!allow_stale_refs && rset->is_empty())); 3458 } 3459 3460 public: 3461 RegisterHumongousWithInCSetFastTestClosure() 3462 : _total_humongous(0), 3463 _candidate_humongous(0), 3464 _dcq(&JavaThread::dirty_card_queue_set()) { 3465 } 3466 3467 virtual bool doHeapRegion(HeapRegion* r) { 3468 if (!r->is_starts_humongous()) { 3469 return false; 3470 } 3471 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3472 3473 uint region_idx = r->hrm_index(); 3474 bool is_candidate = humongous_region_is_candidate(region_idx); 3475 // Is_candidate already filters out humongous object with large remembered sets. 3476 // If we have a humongous object with a few remembered sets, we simply flush these 3477 // remembered set entries into the DCQS. That will result in automatic 3478 // re-evaluation of their remembered set entries during the following evacuation 3479 // phase. 3480 if (is_candidate) { 3481 if (!r->rem_set()->is_empty()) { 3482 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 3483 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 3484 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 3485 HeapRegionRemSetIterator hrrs(r->rem_set()); 3486 size_t card_index; 3487 while (hrrs.has_next(card_index)) { 3488 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 3489 // The remembered set might contain references to already freed 3490 // regions. Filter out such entries to avoid failing card table 3491 // verification. 3492 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) { 3493 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 3494 *card_ptr = CardTableModRefBS::dirty_card_val(); 3495 _dcq.enqueue(card_ptr); 3496 } 3497 } 3498 } 3499 r->rem_set()->clear_locked(); 3500 } 3501 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 3502 g1h->register_humongous_region_with_cset(region_idx); 3503 _candidate_humongous++; 3504 } 3505 _total_humongous++; 3506 3507 return false; 3508 } 3509 3510 size_t total_humongous() const { return _total_humongous; } 3511 size_t candidate_humongous() const { return _candidate_humongous; } 3512 3513 void flush_rem_set_entries() { _dcq.flush(); } 3514 }; 3515 3516 void G1CollectedHeap::register_humongous_regions_with_cset() { 3517 if (!G1EagerReclaimHumongousObjects) { 3518 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 3519 return; 3520 } 3521 double time = os::elapsed_counter(); 3522 3523 RegisterHumongousWithInCSetFastTestClosure cl; 3524 heap_region_iterate(&cl); 3525 3526 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 3527 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 3528 cl.total_humongous(), 3529 cl.candidate_humongous()); 3530 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3531 3532 if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) { 3533 clear_humongous_is_live_table(); 3534 } 3535 3536 // Finally flush all remembered set entries to re-check into the global DCQS. 3537 cl.flush_rem_set_entries(); 3538 } 3539 3540 void 3541 G1CollectedHeap::setup_surviving_young_words() { 3542 assert(_surviving_young_words == NULL, "pre-condition"); 3543 uint array_length = g1_policy()->young_cset_region_length(); 3544 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3545 if (_surviving_young_words == NULL) { 3546 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3547 "Not enough space for young surv words summary."); 3548 } 3549 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3550 #ifdef ASSERT 3551 for (uint i = 0; i < array_length; ++i) { 3552 assert( _surviving_young_words[i] == 0, "memset above" ); 3553 } 3554 #endif // !ASSERT 3555 } 3556 3557 void 3558 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3559 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3560 uint array_length = g1_policy()->young_cset_region_length(); 3561 for (uint i = 0; i < array_length; ++i) { 3562 _surviving_young_words[i] += surv_young_words[i]; 3563 } 3564 } 3565 3566 void 3567 G1CollectedHeap::cleanup_surviving_young_words() { 3568 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3569 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words); 3570 _surviving_young_words = NULL; 3571 } 3572 3573 #ifdef ASSERT 3574 class VerifyCSetClosure: public HeapRegionClosure { 3575 public: 3576 bool doHeapRegion(HeapRegion* hr) { 3577 // Here we check that the CSet region's RSet is ready for parallel 3578 // iteration. The fields that we'll verify are only manipulated 3579 // when the region is part of a CSet and is collected. Afterwards, 3580 // we reset these fields when we clear the region's RSet (when the 3581 // region is freed) so they are ready when the region is 3582 // re-allocated. The only exception to this is if there's an 3583 // evacuation failure and instead of freeing the region we leave 3584 // it in the heap. In that case, we reset these fields during 3585 // evacuation failure handling. 3586 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3587 3588 // Here's a good place to add any other checks we'd like to 3589 // perform on CSet regions. 3590 return false; 3591 } 3592 }; 3593 #endif // ASSERT 3594 3595 #if TASKQUEUE_STATS 3596 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3597 st->print_raw_cr("GC Task Stats"); 3598 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3599 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3600 } 3601 3602 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3603 print_taskqueue_stats_hdr(st); 3604 3605 TaskQueueStats totals; 3606 const int n = workers()->total_workers(); 3607 for (int i = 0; i < n; ++i) { 3608 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3609 totals += task_queue(i)->stats; 3610 } 3611 st->print_raw("tot "); totals.print(st); st->cr(); 3612 3613 DEBUG_ONLY(totals.verify()); 3614 } 3615 3616 void G1CollectedHeap::reset_taskqueue_stats() { 3617 const int n = workers()->total_workers(); 3618 for (int i = 0; i < n; ++i) { 3619 task_queue(i)->stats.reset(); 3620 } 3621 } 3622 #endif // TASKQUEUE_STATS 3623 3624 void G1CollectedHeap::log_gc_header() { 3625 if (!G1Log::fine()) { 3626 return; 3627 } 3628 3629 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id()); 3630 3631 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3632 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") 3633 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3634 3635 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3636 } 3637 3638 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3639 if (!G1Log::fine()) { 3640 return; 3641 } 3642 3643 if (G1Log::finer()) { 3644 if (evacuation_failed()) { 3645 gclog_or_tty->print(" (to-space exhausted)"); 3646 } 3647 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3648 g1_policy()->phase_times()->note_gc_end(); 3649 g1_policy()->phase_times()->print(pause_time_sec); 3650 g1_policy()->print_detailed_heap_transition(); 3651 } else { 3652 if (evacuation_failed()) { 3653 gclog_or_tty->print("--"); 3654 } 3655 g1_policy()->print_heap_transition(); 3656 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3657 } 3658 gclog_or_tty->flush(); 3659 } 3660 3661 bool 3662 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3663 assert_at_safepoint(true /* should_be_vm_thread */); 3664 guarantee(!is_gc_active(), "collection is not reentrant"); 3665 3666 if (GC_locker::check_active_before_gc()) { 3667 return false; 3668 } 3669 3670 _gc_timer_stw->register_gc_start(); 3671 3672 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3673 3674 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3675 ResourceMark rm; 3676 3677 print_heap_before_gc(); 3678 trace_heap_before_gc(_gc_tracer_stw); 3679 3680 verify_region_sets_optional(); 3681 verify_dirty_young_regions(); 3682 3683 // This call will decide whether this pause is an initial-mark 3684 // pause. If it is, during_initial_mark_pause() will return true 3685 // for the duration of this pause. 3686 g1_policy()->decide_on_conc_mark_initiation(); 3687 3688 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3689 assert(!g1_policy()->during_initial_mark_pause() || 3690 g1_policy()->gcs_are_young(), "sanity"); 3691 3692 // We also do not allow mixed GCs during marking. 3693 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3694 3695 // Record whether this pause is an initial mark. When the current 3696 // thread has completed its logging output and it's safe to signal 3697 // the CM thread, the flag's value in the policy has been reset. 3698 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3699 3700 // Inner scope for scope based logging, timers, and stats collection 3701 { 3702 EvacuationInfo evacuation_info; 3703 3704 if (g1_policy()->during_initial_mark_pause()) { 3705 // We are about to start a marking cycle, so we increment the 3706 // full collection counter. 3707 increment_old_marking_cycles_started(); 3708 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3709 } 3710 3711 _gc_tracer_stw->report_yc_type(yc_type()); 3712 3713 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3714 3715 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 3716 workers()->active_workers(), 3717 Threads::number_of_non_daemon_threads()); 3718 assert(UseDynamicNumberOfGCThreads || 3719 active_workers == workers()->total_workers(), 3720 "If not dynamic should be using all the workers"); 3721 workers()->set_active_workers(active_workers); 3722 3723 double pause_start_sec = os::elapsedTime(); 3724 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress()); 3725 log_gc_header(); 3726 3727 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3728 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3729 3730 // If the secondary_free_list is not empty, append it to the 3731 // free_list. No need to wait for the cleanup operation to finish; 3732 // the region allocation code will check the secondary_free_list 3733 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3734 // set, skip this step so that the region allocation code has to 3735 // get entries from the secondary_free_list. 3736 if (!G1StressConcRegionFreeing) { 3737 append_secondary_free_list_if_not_empty_with_lock(); 3738 } 3739 3740 assert(check_young_list_well_formed(), "young list should be well formed"); 3741 3742 // Don't dynamically change the number of GC threads this early. A value of 3743 // 0 is used to indicate serial work. When parallel work is done, 3744 // it will be set. 3745 3746 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3747 IsGCActiveMark x; 3748 3749 gc_prologue(false); 3750 increment_total_collections(false /* full gc */); 3751 increment_gc_time_stamp(); 3752 3753 verify_before_gc(); 3754 3755 check_bitmaps("GC Start"); 3756 3757 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3758 3759 // Please see comment in g1CollectedHeap.hpp and 3760 // G1CollectedHeap::ref_processing_init() to see how 3761 // reference processing currently works in G1. 3762 3763 // Enable discovery in the STW reference processor 3764 ref_processor_stw()->enable_discovery(); 3765 3766 { 3767 // We want to temporarily turn off discovery by the 3768 // CM ref processor, if necessary, and turn it back on 3769 // on again later if we do. Using a scoped 3770 // NoRefDiscovery object will do this. 3771 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3772 3773 // Forget the current alloc region (we might even choose it to be part 3774 // of the collection set!). 3775 _allocator->release_mutator_alloc_region(); 3776 3777 // We should call this after we retire the mutator alloc 3778 // region(s) so that all the ALLOC / RETIRE events are generated 3779 // before the start GC event. 3780 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3781 3782 // This timing is only used by the ergonomics to handle our pause target. 3783 // It is unclear why this should not include the full pause. We will 3784 // investigate this in CR 7178365. 3785 // 3786 // Preserving the old comment here if that helps the investigation: 3787 // 3788 // The elapsed time induced by the start time below deliberately elides 3789 // the possible verification above. 3790 double sample_start_time_sec = os::elapsedTime(); 3791 3792 #if YOUNG_LIST_VERBOSE 3793 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 3794 _young_list->print(); 3795 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3796 #endif // YOUNG_LIST_VERBOSE 3797 3798 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3799 3800 double scan_wait_start = os::elapsedTime(); 3801 // We have to wait until the CM threads finish scanning the 3802 // root regions as it's the only way to ensure that all the 3803 // objects on them have been correctly scanned before we start 3804 // moving them during the GC. 3805 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3806 double wait_time_ms = 0.0; 3807 if (waited) { 3808 double scan_wait_end = os::elapsedTime(); 3809 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3810 } 3811 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3812 3813 #if YOUNG_LIST_VERBOSE 3814 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 3815 _young_list->print(); 3816 #endif // YOUNG_LIST_VERBOSE 3817 3818 if (g1_policy()->during_initial_mark_pause()) { 3819 concurrent_mark()->checkpointRootsInitialPre(); 3820 } 3821 3822 #if YOUNG_LIST_VERBOSE 3823 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 3824 _young_list->print(); 3825 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3826 #endif // YOUNG_LIST_VERBOSE 3827 3828 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 3829 3830 register_humongous_regions_with_cset(); 3831 3832 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3833 3834 _cm->note_start_of_gc(); 3835 // We should not verify the per-thread SATB buffers given that 3836 // we have not filtered them yet (we'll do so during the 3837 // GC). We also call this after finalize_cset() to 3838 // ensure that the CSet has been finalized. 3839 _cm->verify_no_cset_oops(true /* verify_stacks */, 3840 true /* verify_enqueued_buffers */, 3841 false /* verify_thread_buffers */, 3842 true /* verify_fingers */); 3843 3844 if (_hr_printer.is_active()) { 3845 HeapRegion* hr = g1_policy()->collection_set(); 3846 while (hr != NULL) { 3847 _hr_printer.cset(hr); 3848 hr = hr->next_in_collection_set(); 3849 } 3850 } 3851 3852 #ifdef ASSERT 3853 VerifyCSetClosure cl; 3854 collection_set_iterate(&cl); 3855 #endif // ASSERT 3856 3857 setup_surviving_young_words(); 3858 3859 // Initialize the GC alloc regions. 3860 _allocator->init_gc_alloc_regions(evacuation_info); 3861 3862 // Actually do the work... 3863 evacuate_collection_set(evacuation_info); 3864 3865 // We do this to mainly verify the per-thread SATB buffers 3866 // (which have been filtered by now) since we didn't verify 3867 // them earlier. No point in re-checking the stacks / enqueued 3868 // buffers given that the CSet has not changed since last time 3869 // we checked. 3870 _cm->verify_no_cset_oops(false /* verify_stacks */, 3871 false /* verify_enqueued_buffers */, 3872 true /* verify_thread_buffers */, 3873 true /* verify_fingers */); 3874 3875 free_collection_set(g1_policy()->collection_set(), evacuation_info); 3876 3877 eagerly_reclaim_humongous_regions(); 3878 3879 g1_policy()->clear_collection_set(); 3880 3881 cleanup_surviving_young_words(); 3882 3883 // Start a new incremental collection set for the next pause. 3884 g1_policy()->start_incremental_cset_building(); 3885 3886 clear_cset_fast_test(); 3887 3888 _young_list->reset_sampled_info(); 3889 3890 // Don't check the whole heap at this point as the 3891 // GC alloc regions from this pause have been tagged 3892 // as survivors and moved on to the survivor list. 3893 // Survivor regions will fail the !is_young() check. 3894 assert(check_young_list_empty(false /* check_heap */), 3895 "young list should be empty"); 3896 3897 #if YOUNG_LIST_VERBOSE 3898 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 3899 _young_list->print(); 3900 #endif // YOUNG_LIST_VERBOSE 3901 3902 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 3903 _young_list->first_survivor_region(), 3904 _young_list->last_survivor_region()); 3905 3906 _young_list->reset_auxilary_lists(); 3907 3908 if (evacuation_failed()) { 3909 _allocator->set_used(recalculate_used()); 3910 uint n_queues = MAX2((int)ParallelGCThreads, 1); 3911 for (uint i = 0; i < n_queues; i++) { 3912 if (_evacuation_failed_info_array[i].has_failed()) { 3913 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3914 } 3915 } 3916 } else { 3917 // The "used" of the the collection set have already been subtracted 3918 // when they were freed. Add in the bytes evacuated. 3919 _allocator->increase_used(g1_policy()->bytes_copied_during_gc()); 3920 } 3921 3922 if (g1_policy()->during_initial_mark_pause()) { 3923 // We have to do this before we notify the CM threads that 3924 // they can start working to make sure that all the 3925 // appropriate initialization is done on the CM object. 3926 concurrent_mark()->checkpointRootsInitialPost(); 3927 set_marking_started(); 3928 // Note that we don't actually trigger the CM thread at 3929 // this point. We do that later when we're sure that 3930 // the current thread has completed its logging output. 3931 } 3932 3933 allocate_dummy_regions(); 3934 3935 #if YOUNG_LIST_VERBOSE 3936 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 3937 _young_list->print(); 3938 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3939 #endif // YOUNG_LIST_VERBOSE 3940 3941 _allocator->init_mutator_alloc_region(); 3942 3943 { 3944 size_t expand_bytes = g1_policy()->expansion_amount(); 3945 if (expand_bytes > 0) { 3946 size_t bytes_before = capacity(); 3947 // No need for an ergo verbose message here, 3948 // expansion_amount() does this when it returns a value > 0. 3949 if (!expand(expand_bytes)) { 3950 // We failed to expand the heap. Cannot do anything about it. 3951 } 3952 } 3953 } 3954 3955 // We redo the verification but now wrt to the new CSet which 3956 // has just got initialized after the previous CSet was freed. 3957 _cm->verify_no_cset_oops(true /* verify_stacks */, 3958 true /* verify_enqueued_buffers */, 3959 true /* verify_thread_buffers */, 3960 true /* verify_fingers */); 3961 _cm->note_end_of_gc(); 3962 3963 // This timing is only used by the ergonomics to handle our pause target. 3964 // It is unclear why this should not include the full pause. We will 3965 // investigate this in CR 7178365. 3966 double sample_end_time_sec = os::elapsedTime(); 3967 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3968 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 3969 3970 MemoryService::track_memory_usage(); 3971 3972 // In prepare_for_verify() below we'll need to scan the deferred 3973 // update buffers to bring the RSets up-to-date if 3974 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 3975 // the update buffers we'll probably need to scan cards on the 3976 // regions we just allocated to (i.e., the GC alloc 3977 // regions). However, during the last GC we called 3978 // set_saved_mark() on all the GC alloc regions, so card 3979 // scanning might skip the [saved_mark_word()...top()] area of 3980 // those regions (i.e., the area we allocated objects into 3981 // during the last GC). But it shouldn't. Given that 3982 // saved_mark_word() is conditional on whether the GC time stamp 3983 // on the region is current or not, by incrementing the GC time 3984 // stamp here we invalidate all the GC time stamps on all the 3985 // regions and saved_mark_word() will simply return top() for 3986 // all the regions. This is a nicer way of ensuring this rather 3987 // than iterating over the regions and fixing them. In fact, the 3988 // GC time stamp increment here also ensures that 3989 // saved_mark_word() will return top() between pauses, i.e., 3990 // during concurrent refinement. So we don't need the 3991 // is_gc_active() check to decided which top to use when 3992 // scanning cards (see CR 7039627). 3993 increment_gc_time_stamp(); 3994 3995 verify_after_gc(); 3996 check_bitmaps("GC End"); 3997 3998 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 3999 ref_processor_stw()->verify_no_references_recorded(); 4000 4001 // CM reference discovery will be re-enabled if necessary. 4002 } 4003 4004 // We should do this after we potentially expand the heap so 4005 // that all the COMMIT events are generated before the end GC 4006 // event, and after we retire the GC alloc regions so that all 4007 // RETIRE events are generated before the end GC event. 4008 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4009 4010 #ifdef TRACESPINNING 4011 ParallelTaskTerminator::print_termination_counts(); 4012 #endif 4013 4014 gc_epilogue(false); 4015 } 4016 4017 // Print the remainder of the GC log output. 4018 log_gc_footer(os::elapsedTime() - pause_start_sec); 4019 4020 // It is not yet to safe to tell the concurrent mark to 4021 // start as we have some optional output below. We don't want the 4022 // output from the concurrent mark thread interfering with this 4023 // logging output either. 4024 4025 _hrm.verify_optional(); 4026 verify_region_sets_optional(); 4027 4028 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats()); 4029 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4030 4031 print_heap_after_gc(); 4032 trace_heap_after_gc(_gc_tracer_stw); 4033 4034 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4035 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4036 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4037 // before any GC notifications are raised. 4038 g1mm()->update_sizes(); 4039 4040 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4041 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4042 _gc_timer_stw->register_gc_end(); 4043 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4044 } 4045 // It should now be safe to tell the concurrent mark thread to start 4046 // without its logging output interfering with the logging output 4047 // that came from the pause. 4048 4049 if (should_start_conc_mark) { 4050 // CAUTION: after the doConcurrentMark() call below, 4051 // the concurrent marking thread(s) could be running 4052 // concurrently with us. Make sure that anything after 4053 // this point does not assume that we are the only GC thread 4054 // running. Note: of course, the actual marking work will 4055 // not start until the safepoint itself is released in 4056 // SuspendibleThreadSet::desynchronize(). 4057 doConcurrentMark(); 4058 } 4059 4060 return true; 4061 } 4062 4063 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4064 _drain_in_progress = false; 4065 set_evac_failure_closure(cl); 4066 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4067 } 4068 4069 void G1CollectedHeap::finalize_for_evac_failure() { 4070 assert(_evac_failure_scan_stack != NULL && 4071 _evac_failure_scan_stack->length() == 0, 4072 "Postcondition"); 4073 assert(!_drain_in_progress, "Postcondition"); 4074 delete _evac_failure_scan_stack; 4075 _evac_failure_scan_stack = NULL; 4076 } 4077 4078 void G1CollectedHeap::remove_self_forwarding_pointers() { 4079 double remove_self_forwards_start = os::elapsedTime(); 4080 4081 set_par_threads(); 4082 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4083 workers()->run_task(&rsfp_task); 4084 set_par_threads(0); 4085 4086 // Now restore saved marks, if any. 4087 assert(_objs_with_preserved_marks.size() == 4088 _preserved_marks_of_objs.size(), "Both or none."); 4089 while (!_objs_with_preserved_marks.is_empty()) { 4090 oop obj = _objs_with_preserved_marks.pop(); 4091 markOop m = _preserved_marks_of_objs.pop(); 4092 obj->set_mark(m); 4093 } 4094 _objs_with_preserved_marks.clear(true); 4095 _preserved_marks_of_objs.clear(true); 4096 4097 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4098 } 4099 4100 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4101 _evac_failure_scan_stack->push(obj); 4102 } 4103 4104 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4105 assert(_evac_failure_scan_stack != NULL, "precondition"); 4106 4107 while (_evac_failure_scan_stack->length() > 0) { 4108 oop obj = _evac_failure_scan_stack->pop(); 4109 _evac_failure_closure->set_region(heap_region_containing(obj)); 4110 obj->oop_iterate_backwards(_evac_failure_closure); 4111 } 4112 } 4113 4114 oop 4115 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4116 oop old) { 4117 assert(obj_in_cs(old), 4118 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4119 (HeapWord*) old)); 4120 markOop m = old->mark(); 4121 oop forward_ptr = old->forward_to_atomic(old); 4122 if (forward_ptr == NULL) { 4123 // Forward-to-self succeeded. 4124 assert(_par_scan_state != NULL, "par scan state"); 4125 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4126 uint queue_num = _par_scan_state->queue_num(); 4127 4128 _evacuation_failed = true; 4129 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4130 if (_evac_failure_closure != cl) { 4131 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4132 assert(!_drain_in_progress, 4133 "Should only be true while someone holds the lock."); 4134 // Set the global evac-failure closure to the current thread's. 4135 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4136 set_evac_failure_closure(cl); 4137 // Now do the common part. 4138 handle_evacuation_failure_common(old, m); 4139 // Reset to NULL. 4140 set_evac_failure_closure(NULL); 4141 } else { 4142 // The lock is already held, and this is recursive. 4143 assert(_drain_in_progress, "This should only be the recursive case."); 4144 handle_evacuation_failure_common(old, m); 4145 } 4146 return old; 4147 } else { 4148 // Forward-to-self failed. Either someone else managed to allocate 4149 // space for this object (old != forward_ptr) or they beat us in 4150 // self-forwarding it (old == forward_ptr). 4151 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4152 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4153 "should not be in the CSet", 4154 (HeapWord*) old, (HeapWord*) forward_ptr)); 4155 return forward_ptr; 4156 } 4157 } 4158 4159 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4160 preserve_mark_if_necessary(old, m); 4161 4162 HeapRegion* r = heap_region_containing(old); 4163 if (!r->evacuation_failed()) { 4164 r->set_evacuation_failed(true); 4165 _hr_printer.evac_failure(r); 4166 } 4167 4168 push_on_evac_failure_scan_stack(old); 4169 4170 if (!_drain_in_progress) { 4171 // prevent recursion in copy_to_survivor_space() 4172 _drain_in_progress = true; 4173 drain_evac_failure_scan_stack(); 4174 _drain_in_progress = false; 4175 } 4176 } 4177 4178 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4179 assert(evacuation_failed(), "Oversaving!"); 4180 // We want to call the "for_promotion_failure" version only in the 4181 // case of a promotion failure. 4182 if (m->must_be_preserved_for_promotion_failure(obj)) { 4183 _objs_with_preserved_marks.push(obj); 4184 _preserved_marks_of_objs.push(m); 4185 } 4186 } 4187 4188 void G1ParCopyHelper::mark_object(oop obj) { 4189 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); 4190 4191 // We know that the object is not moving so it's safe to read its size. 4192 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4193 } 4194 4195 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4196 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4197 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4198 assert(from_obj != to_obj, "should not be self-forwarded"); 4199 4200 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); 4201 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); 4202 4203 // The object might be in the process of being copied by another 4204 // worker so we cannot trust that its to-space image is 4205 // well-formed. So we have to read its size from its from-space 4206 // image which we know should not be changing. 4207 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4208 } 4209 4210 template <class T> 4211 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4212 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4213 _scanned_klass->record_modified_oops(); 4214 } 4215 } 4216 4217 template <G1Barrier barrier, G1Mark do_mark_object> 4218 template <class T> 4219 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4220 T heap_oop = oopDesc::load_heap_oop(p); 4221 4222 if (oopDesc::is_null(heap_oop)) { 4223 return; 4224 } 4225 4226 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4227 4228 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4229 4230 const InCSetState state = _g1->in_cset_state(obj); 4231 if (state.is_in_cset()) { 4232 oop forwardee; 4233 markOop m = obj->mark(); 4234 if (m->is_marked()) { 4235 forwardee = (oop) m->decode_pointer(); 4236 } else { 4237 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m); 4238 } 4239 assert(forwardee != NULL, "forwardee should not be NULL"); 4240 oopDesc::encode_store_heap_oop(p, forwardee); 4241 if (do_mark_object != G1MarkNone && forwardee != obj) { 4242 // If the object is self-forwarded we don't need to explicitly 4243 // mark it, the evacuation failure protocol will do so. 4244 mark_forwarded_object(obj, forwardee); 4245 } 4246 4247 if (barrier == G1BarrierKlass) { 4248 do_klass_barrier(p, forwardee); 4249 } 4250 } else { 4251 if (state.is_humongous()) { 4252 _g1->set_humongous_is_live(obj); 4253 } 4254 // The object is not in collection set. If we're a root scanning 4255 // closure during an initial mark pause then attempt to mark the object. 4256 if (do_mark_object == G1MarkFromRoot) { 4257 mark_object(obj); 4258 } 4259 } 4260 4261 if (barrier == G1BarrierEvac) { 4262 _par_scan_state->update_rs(_from, p, _worker_id); 4263 } 4264 } 4265 4266 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p); 4267 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p); 4268 4269 class G1ParEvacuateFollowersClosure : public VoidClosure { 4270 protected: 4271 G1CollectedHeap* _g1h; 4272 G1ParScanThreadState* _par_scan_state; 4273 RefToScanQueueSet* _queues; 4274 ParallelTaskTerminator* _terminator; 4275 4276 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4277 RefToScanQueueSet* queues() { return _queues; } 4278 ParallelTaskTerminator* terminator() { return _terminator; } 4279 4280 public: 4281 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4282 G1ParScanThreadState* par_scan_state, 4283 RefToScanQueueSet* queues, 4284 ParallelTaskTerminator* terminator) 4285 : _g1h(g1h), _par_scan_state(par_scan_state), 4286 _queues(queues), _terminator(terminator) {} 4287 4288 void do_void(); 4289 4290 private: 4291 inline bool offer_termination(); 4292 }; 4293 4294 bool G1ParEvacuateFollowersClosure::offer_termination() { 4295 G1ParScanThreadState* const pss = par_scan_state(); 4296 pss->start_term_time(); 4297 const bool res = terminator()->offer_termination(); 4298 pss->end_term_time(); 4299 return res; 4300 } 4301 4302 void G1ParEvacuateFollowersClosure::do_void() { 4303 G1ParScanThreadState* const pss = par_scan_state(); 4304 pss->trim_queue(); 4305 do { 4306 pss->steal_and_trim_queue(queues()); 4307 } while (!offer_termination()); 4308 } 4309 4310 class G1KlassScanClosure : public KlassClosure { 4311 G1ParCopyHelper* _closure; 4312 bool _process_only_dirty; 4313 int _count; 4314 public: 4315 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4316 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4317 void do_klass(Klass* klass) { 4318 // If the klass has not been dirtied we know that there's 4319 // no references into the young gen and we can skip it. 4320 if (!_process_only_dirty || klass->has_modified_oops()) { 4321 // Clean the klass since we're going to scavenge all the metadata. 4322 klass->clear_modified_oops(); 4323 4324 // Tell the closure that this klass is the Klass to scavenge 4325 // and is the one to dirty if oops are left pointing into the young gen. 4326 _closure->set_scanned_klass(klass); 4327 4328 klass->oops_do(_closure); 4329 4330 _closure->set_scanned_klass(NULL); 4331 } 4332 _count++; 4333 } 4334 }; 4335 4336 class G1ParTask : public AbstractGangTask { 4337 protected: 4338 G1CollectedHeap* _g1h; 4339 RefToScanQueueSet *_queues; 4340 G1RootProcessor* _root_processor; 4341 ParallelTaskTerminator _terminator; 4342 uint _n_workers; 4343 4344 Mutex _stats_lock; 4345 Mutex* stats_lock() { return &_stats_lock; } 4346 4347 public: 4348 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor) 4349 : AbstractGangTask("G1 collection"), 4350 _g1h(g1h), 4351 _queues(task_queues), 4352 _root_processor(root_processor), 4353 _terminator(0, _queues), 4354 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4355 {} 4356 4357 RefToScanQueueSet* queues() { return _queues; } 4358 4359 RefToScanQueue *work_queue(int i) { 4360 return queues()->queue(i); 4361 } 4362 4363 ParallelTaskTerminator* terminator() { return &_terminator; } 4364 4365 virtual void set_for_termination(int active_workers) { 4366 _root_processor->set_num_workers(active_workers); 4367 terminator()->reset_for_reuse(active_workers); 4368 _n_workers = active_workers; 4369 } 4370 4371 // Helps out with CLD processing. 4372 // 4373 // During InitialMark we need to: 4374 // 1) Scavenge all CLDs for the young GC. 4375 // 2) Mark all objects directly reachable from strong CLDs. 4376 template <G1Mark do_mark_object> 4377 class G1CLDClosure : public CLDClosure { 4378 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure; 4379 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure; 4380 G1KlassScanClosure _klass_in_cld_closure; 4381 bool _claim; 4382 4383 public: 4384 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure, 4385 bool only_young, bool claim) 4386 : _oop_closure(oop_closure), 4387 _oop_in_klass_closure(oop_closure->g1(), 4388 oop_closure->pss(), 4389 oop_closure->rp()), 4390 _klass_in_cld_closure(&_oop_in_klass_closure, only_young), 4391 _claim(claim) { 4392 4393 } 4394 4395 void do_cld(ClassLoaderData* cld) { 4396 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim); 4397 } 4398 }; 4399 4400 void work(uint worker_id) { 4401 if (worker_id >= _n_workers) return; // no work needed this round 4402 4403 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime()); 4404 4405 { 4406 ResourceMark rm; 4407 HandleMark hm; 4408 4409 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4410 4411 G1ParScanThreadState pss(_g1h, worker_id, rp); 4412 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 4413 4414 pss.set_evac_failure_closure(&evac_failure_cl); 4415 4416 bool only_young = _g1h->g1_policy()->gcs_are_young(); 4417 4418 // Non-IM young GC. 4419 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp); 4420 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl, 4421 only_young, // Only process dirty klasses. 4422 false); // No need to claim CLDs. 4423 // IM young GC. 4424 // Strong roots closures. 4425 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp); 4426 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl, 4427 false, // Process all klasses. 4428 true); // Need to claim CLDs. 4429 // Weak roots closures. 4430 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp); 4431 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl, 4432 false, // Process all klasses. 4433 true); // Need to claim CLDs. 4434 4435 OopClosure* strong_root_cl; 4436 OopClosure* weak_root_cl; 4437 CLDClosure* strong_cld_cl; 4438 CLDClosure* weak_cld_cl; 4439 4440 bool trace_metadata = false; 4441 4442 if (_g1h->g1_policy()->during_initial_mark_pause()) { 4443 // We also need to mark copied objects. 4444 strong_root_cl = &scan_mark_root_cl; 4445 strong_cld_cl = &scan_mark_cld_cl; 4446 if (ClassUnloadingWithConcurrentMark) { 4447 weak_root_cl = &scan_mark_weak_root_cl; 4448 weak_cld_cl = &scan_mark_weak_cld_cl; 4449 trace_metadata = true; 4450 } else { 4451 weak_root_cl = &scan_mark_root_cl; 4452 weak_cld_cl = &scan_mark_cld_cl; 4453 } 4454 } else { 4455 strong_root_cl = &scan_only_root_cl; 4456 weak_root_cl = &scan_only_root_cl; 4457 strong_cld_cl = &scan_only_cld_cl; 4458 weak_cld_cl = &scan_only_cld_cl; 4459 } 4460 4461 pss.start_strong_roots(); 4462 4463 _root_processor->evacuate_roots(strong_root_cl, 4464 weak_root_cl, 4465 strong_cld_cl, 4466 weak_cld_cl, 4467 trace_metadata, 4468 worker_id); 4469 4470 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4471 _root_processor->scan_remembered_sets(&push_heap_rs_cl, 4472 weak_root_cl, 4473 worker_id); 4474 pss.end_strong_roots(); 4475 4476 { 4477 double start = os::elapsedTime(); 4478 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4479 evac.do_void(); 4480 double elapsed_sec = os::elapsedTime() - start; 4481 double term_sec = pss.term_time(); 4482 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 4483 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 4484 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts()); 4485 } 4486 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4487 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4488 4489 if (PrintTerminationStats) { 4490 MutexLocker x(stats_lock()); 4491 pss.print_termination_stats(worker_id); 4492 } 4493 4494 assert(pss.queue_is_empty(), "should be empty"); 4495 4496 // Close the inner scope so that the ResourceMark and HandleMark 4497 // destructors are executed here and are included as part of the 4498 // "GC Worker Time". 4499 } 4500 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 4501 } 4502 }; 4503 4504 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4505 private: 4506 BoolObjectClosure* _is_alive; 4507 int _initial_string_table_size; 4508 int _initial_symbol_table_size; 4509 4510 bool _process_strings; 4511 int _strings_processed; 4512 int _strings_removed; 4513 4514 bool _process_symbols; 4515 int _symbols_processed; 4516 int _symbols_removed; 4517 4518 public: 4519 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4520 AbstractGangTask("String/Symbol Unlinking"), 4521 _is_alive(is_alive), 4522 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4523 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4524 4525 _initial_string_table_size = StringTable::the_table()->table_size(); 4526 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4527 if (process_strings) { 4528 StringTable::clear_parallel_claimed_index(); 4529 } 4530 if (process_symbols) { 4531 SymbolTable::clear_parallel_claimed_index(); 4532 } 4533 } 4534 4535 ~G1StringSymbolTableUnlinkTask() { 4536 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4537 err_msg("claim value %d after unlink less than initial string table size %d", 4538 StringTable::parallel_claimed_index(), _initial_string_table_size)); 4539 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4540 err_msg("claim value %d after unlink less than initial symbol table size %d", 4541 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 4542 4543 if (G1TraceStringSymbolTableScrubbing) { 4544 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4545 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 4546 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 4547 strings_processed(), strings_removed(), 4548 symbols_processed(), symbols_removed()); 4549 } 4550 } 4551 4552 void work(uint worker_id) { 4553 int strings_processed = 0; 4554 int strings_removed = 0; 4555 int symbols_processed = 0; 4556 int symbols_removed = 0; 4557 if (_process_strings) { 4558 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4559 Atomic::add(strings_processed, &_strings_processed); 4560 Atomic::add(strings_removed, &_strings_removed); 4561 } 4562 if (_process_symbols) { 4563 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 4564 Atomic::add(symbols_processed, &_symbols_processed); 4565 Atomic::add(symbols_removed, &_symbols_removed); 4566 } 4567 } 4568 4569 size_t strings_processed() const { return (size_t)_strings_processed; } 4570 size_t strings_removed() const { return (size_t)_strings_removed; } 4571 4572 size_t symbols_processed() const { return (size_t)_symbols_processed; } 4573 size_t symbols_removed() const { return (size_t)_symbols_removed; } 4574 }; 4575 4576 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 4577 private: 4578 static Monitor* _lock; 4579 4580 BoolObjectClosure* const _is_alive; 4581 const bool _unloading_occurred; 4582 const uint _num_workers; 4583 4584 // Variables used to claim nmethods. 4585 nmethod* _first_nmethod; 4586 volatile nmethod* _claimed_nmethod; 4587 4588 // The list of nmethods that need to be processed by the second pass. 4589 volatile nmethod* _postponed_list; 4590 volatile uint _num_entered_barrier; 4591 4592 public: 4593 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 4594 _is_alive(is_alive), 4595 _unloading_occurred(unloading_occurred), 4596 _num_workers(num_workers), 4597 _first_nmethod(NULL), 4598 _claimed_nmethod(NULL), 4599 _postponed_list(NULL), 4600 _num_entered_barrier(0) 4601 { 4602 nmethod::increase_unloading_clock(); 4603 // Get first alive nmethod 4604 NMethodIterator iter = NMethodIterator(); 4605 if(iter.next_alive()) { 4606 _first_nmethod = iter.method(); 4607 } 4608 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 4609 } 4610 4611 ~G1CodeCacheUnloadingTask() { 4612 CodeCache::verify_clean_inline_caches(); 4613 4614 CodeCache::set_needs_cache_clean(false); 4615 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 4616 4617 CodeCache::verify_icholder_relocations(); 4618 } 4619 4620 private: 4621 void add_to_postponed_list(nmethod* nm) { 4622 nmethod* old; 4623 do { 4624 old = (nmethod*)_postponed_list; 4625 nm->set_unloading_next(old); 4626 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 4627 } 4628 4629 void clean_nmethod(nmethod* nm) { 4630 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 4631 4632 if (postponed) { 4633 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 4634 add_to_postponed_list(nm); 4635 } 4636 4637 // Mark that this thread has been cleaned/unloaded. 4638 // After this call, it will be safe to ask if this nmethod was unloaded or not. 4639 nm->set_unloading_clock(nmethod::global_unloading_clock()); 4640 } 4641 4642 void clean_nmethod_postponed(nmethod* nm) { 4643 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 4644 } 4645 4646 static const int MaxClaimNmethods = 16; 4647 4648 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 4649 nmethod* first; 4650 NMethodIterator last; 4651 4652 do { 4653 *num_claimed_nmethods = 0; 4654 4655 first = (nmethod*)_claimed_nmethod; 4656 last = NMethodIterator(first); 4657 4658 if (first != NULL) { 4659 4660 for (int i = 0; i < MaxClaimNmethods; i++) { 4661 if (!last.next_alive()) { 4662 break; 4663 } 4664 claimed_nmethods[i] = last.method(); 4665 (*num_claimed_nmethods)++; 4666 } 4667 } 4668 4669 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 4670 } 4671 4672 nmethod* claim_postponed_nmethod() { 4673 nmethod* claim; 4674 nmethod* next; 4675 4676 do { 4677 claim = (nmethod*)_postponed_list; 4678 if (claim == NULL) { 4679 return NULL; 4680 } 4681 4682 next = claim->unloading_next(); 4683 4684 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 4685 4686 return claim; 4687 } 4688 4689 public: 4690 // Mark that we're done with the first pass of nmethod cleaning. 4691 void barrier_mark(uint worker_id) { 4692 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4693 _num_entered_barrier++; 4694 if (_num_entered_barrier == _num_workers) { 4695 ml.notify_all(); 4696 } 4697 } 4698 4699 // See if we have to wait for the other workers to 4700 // finish their first-pass nmethod cleaning work. 4701 void barrier_wait(uint worker_id) { 4702 if (_num_entered_barrier < _num_workers) { 4703 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4704 while (_num_entered_barrier < _num_workers) { 4705 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 4706 } 4707 } 4708 } 4709 4710 // Cleaning and unloading of nmethods. Some work has to be postponed 4711 // to the second pass, when we know which nmethods survive. 4712 void work_first_pass(uint worker_id) { 4713 // The first nmethods is claimed by the first worker. 4714 if (worker_id == 0 && _first_nmethod != NULL) { 4715 clean_nmethod(_first_nmethod); 4716 _first_nmethod = NULL; 4717 } 4718 4719 int num_claimed_nmethods; 4720 nmethod* claimed_nmethods[MaxClaimNmethods]; 4721 4722 while (true) { 4723 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 4724 4725 if (num_claimed_nmethods == 0) { 4726 break; 4727 } 4728 4729 for (int i = 0; i < num_claimed_nmethods; i++) { 4730 clean_nmethod(claimed_nmethods[i]); 4731 } 4732 } 4733 } 4734 4735 void work_second_pass(uint worker_id) { 4736 nmethod* nm; 4737 // Take care of postponed nmethods. 4738 while ((nm = claim_postponed_nmethod()) != NULL) { 4739 clean_nmethod_postponed(nm); 4740 } 4741 } 4742 }; 4743 4744 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 4745 4746 class G1KlassCleaningTask : public StackObj { 4747 BoolObjectClosure* _is_alive; 4748 volatile jint _clean_klass_tree_claimed; 4749 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 4750 4751 public: 4752 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 4753 _is_alive(is_alive), 4754 _clean_klass_tree_claimed(0), 4755 _klass_iterator() { 4756 } 4757 4758 private: 4759 bool claim_clean_klass_tree_task() { 4760 if (_clean_klass_tree_claimed) { 4761 return false; 4762 } 4763 4764 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 4765 } 4766 4767 InstanceKlass* claim_next_klass() { 4768 Klass* klass; 4769 do { 4770 klass =_klass_iterator.next_klass(); 4771 } while (klass != NULL && !klass->oop_is_instance()); 4772 4773 return (InstanceKlass*)klass; 4774 } 4775 4776 public: 4777 4778 void clean_klass(InstanceKlass* ik) { 4779 ik->clean_implementors_list(_is_alive); 4780 ik->clean_method_data(_is_alive); 4781 4782 // G1 specific cleanup work that has 4783 // been moved here to be done in parallel. 4784 ik->clean_dependent_nmethods(); 4785 } 4786 4787 void work() { 4788 ResourceMark rm; 4789 4790 // One worker will clean the subklass/sibling klass tree. 4791 if (claim_clean_klass_tree_task()) { 4792 Klass::clean_subklass_tree(_is_alive); 4793 } 4794 4795 // All workers will help cleaning the classes, 4796 InstanceKlass* klass; 4797 while ((klass = claim_next_klass()) != NULL) { 4798 clean_klass(klass); 4799 } 4800 } 4801 }; 4802 4803 // To minimize the remark pause times, the tasks below are done in parallel. 4804 class G1ParallelCleaningTask : public AbstractGangTask { 4805 private: 4806 G1StringSymbolTableUnlinkTask _string_symbol_task; 4807 G1CodeCacheUnloadingTask _code_cache_task; 4808 G1KlassCleaningTask _klass_cleaning_task; 4809 4810 public: 4811 // The constructor is run in the VMThread. 4812 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 4813 AbstractGangTask("Parallel Cleaning"), 4814 _string_symbol_task(is_alive, process_strings, process_symbols), 4815 _code_cache_task(num_workers, is_alive, unloading_occurred), 4816 _klass_cleaning_task(is_alive) { 4817 } 4818 4819 // The parallel work done by all worker threads. 4820 void work(uint worker_id) { 4821 // Do first pass of code cache cleaning. 4822 _code_cache_task.work_first_pass(worker_id); 4823 4824 // Let the threads mark that the first pass is done. 4825 _code_cache_task.barrier_mark(worker_id); 4826 4827 // Clean the Strings and Symbols. 4828 _string_symbol_task.work(worker_id); 4829 4830 // Wait for all workers to finish the first code cache cleaning pass. 4831 _code_cache_task.barrier_wait(worker_id); 4832 4833 // Do the second code cache cleaning work, which realize on 4834 // the liveness information gathered during the first pass. 4835 _code_cache_task.work_second_pass(worker_id); 4836 4837 // Clean all klasses that were not unloaded. 4838 _klass_cleaning_task.work(); 4839 } 4840 }; 4841 4842 4843 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 4844 bool process_strings, 4845 bool process_symbols, 4846 bool class_unloading_occurred) { 4847 uint n_workers = workers()->active_workers(); 4848 4849 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 4850 n_workers, class_unloading_occurred); 4851 set_par_threads(n_workers); 4852 workers()->run_task(&g1_unlink_task); 4853 set_par_threads(0); 4854 } 4855 4856 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 4857 bool process_strings, bool process_symbols) { 4858 { 4859 uint n_workers = _g1h->workers()->active_workers(); 4860 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 4861 set_par_threads(n_workers); 4862 workers()->run_task(&g1_unlink_task); 4863 set_par_threads(0); 4864 } 4865 4866 if (G1StringDedup::is_enabled()) { 4867 G1StringDedup::unlink(is_alive); 4868 } 4869 } 4870 4871 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 4872 private: 4873 DirtyCardQueueSet* _queue; 4874 public: 4875 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 4876 4877 virtual void work(uint worker_id) { 4878 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4879 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 4880 4881 RedirtyLoggedCardTableEntryClosure cl; 4882 _queue->par_apply_closure_to_all_completed_buffers(&cl); 4883 4884 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed()); 4885 } 4886 }; 4887 4888 void G1CollectedHeap::redirty_logged_cards() { 4889 double redirty_logged_cards_start = os::elapsedTime(); 4890 4891 uint n_workers = _g1h->workers()->active_workers(); 4892 4893 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 4894 dirty_card_queue_set().reset_for_par_iteration(); 4895 set_par_threads(n_workers); 4896 workers()->run_task(&redirty_task); 4897 set_par_threads(0); 4898 4899 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 4900 dcq.merge_bufferlists(&dirty_card_queue_set()); 4901 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 4902 4903 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 4904 } 4905 4906 // Weak Reference Processing support 4907 4908 // An always "is_alive" closure that is used to preserve referents. 4909 // If the object is non-null then it's alive. Used in the preservation 4910 // of referent objects that are pointed to by reference objects 4911 // discovered by the CM ref processor. 4912 class G1AlwaysAliveClosure: public BoolObjectClosure { 4913 G1CollectedHeap* _g1; 4914 public: 4915 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4916 bool do_object_b(oop p) { 4917 if (p != NULL) { 4918 return true; 4919 } 4920 return false; 4921 } 4922 }; 4923 4924 bool G1STWIsAliveClosure::do_object_b(oop p) { 4925 // An object is reachable if it is outside the collection set, 4926 // or is inside and copied. 4927 return !_g1->obj_in_cs(p) || p->is_forwarded(); 4928 } 4929 4930 // Non Copying Keep Alive closure 4931 class G1KeepAliveClosure: public OopClosure { 4932 G1CollectedHeap* _g1; 4933 public: 4934 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4935 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 4936 void do_oop(oop* p) { 4937 oop obj = *p; 4938 assert(obj != NULL, "the caller should have filtered out NULL values"); 4939 4940 const InCSetState cset_state = _g1->in_cset_state(obj); 4941 if (!cset_state.is_in_cset_or_humongous()) { 4942 return; 4943 } 4944 if (cset_state.is_in_cset()) { 4945 assert( obj->is_forwarded(), "invariant" ); 4946 *p = obj->forwardee(); 4947 } else { 4948 assert(!obj->is_forwarded(), "invariant" ); 4949 assert(cset_state.is_humongous(), 4950 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value())); 4951 _g1->set_humongous_is_live(obj); 4952 } 4953 } 4954 }; 4955 4956 // Copying Keep Alive closure - can be called from both 4957 // serial and parallel code as long as different worker 4958 // threads utilize different G1ParScanThreadState instances 4959 // and different queues. 4960 4961 class G1CopyingKeepAliveClosure: public OopClosure { 4962 G1CollectedHeap* _g1h; 4963 OopClosure* _copy_non_heap_obj_cl; 4964 G1ParScanThreadState* _par_scan_state; 4965 4966 public: 4967 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 4968 OopClosure* non_heap_obj_cl, 4969 G1ParScanThreadState* pss): 4970 _g1h(g1h), 4971 _copy_non_heap_obj_cl(non_heap_obj_cl), 4972 _par_scan_state(pss) 4973 {} 4974 4975 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 4976 virtual void do_oop( oop* p) { do_oop_work(p); } 4977 4978 template <class T> void do_oop_work(T* p) { 4979 oop obj = oopDesc::load_decode_heap_oop(p); 4980 4981 if (_g1h->is_in_cset_or_humongous(obj)) { 4982 // If the referent object has been forwarded (either copied 4983 // to a new location or to itself in the event of an 4984 // evacuation failure) then we need to update the reference 4985 // field and, if both reference and referent are in the G1 4986 // heap, update the RSet for the referent. 4987 // 4988 // If the referent has not been forwarded then we have to keep 4989 // it alive by policy. Therefore we have copy the referent. 4990 // 4991 // If the reference field is in the G1 heap then we can push 4992 // on the PSS queue. When the queue is drained (after each 4993 // phase of reference processing) the object and it's followers 4994 // will be copied, the reference field set to point to the 4995 // new location, and the RSet updated. Otherwise we need to 4996 // use the the non-heap or metadata closures directly to copy 4997 // the referent object and update the pointer, while avoiding 4998 // updating the RSet. 4999 5000 if (_g1h->is_in_g1_reserved(p)) { 5001 _par_scan_state->push_on_queue(p); 5002 } else { 5003 assert(!Metaspace::contains((const void*)p), 5004 err_msg("Unexpectedly found a pointer from metadata: " 5005 PTR_FORMAT, p)); 5006 _copy_non_heap_obj_cl->do_oop(p); 5007 } 5008 } 5009 } 5010 }; 5011 5012 // Serial drain queue closure. Called as the 'complete_gc' 5013 // closure for each discovered list in some of the 5014 // reference processing phases. 5015 5016 class G1STWDrainQueueClosure: public VoidClosure { 5017 protected: 5018 G1CollectedHeap* _g1h; 5019 G1ParScanThreadState* _par_scan_state; 5020 5021 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5022 5023 public: 5024 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5025 _g1h(g1h), 5026 _par_scan_state(pss) 5027 { } 5028 5029 void do_void() { 5030 G1ParScanThreadState* const pss = par_scan_state(); 5031 pss->trim_queue(); 5032 } 5033 }; 5034 5035 // Parallel Reference Processing closures 5036 5037 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5038 // processing during G1 evacuation pauses. 5039 5040 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5041 private: 5042 G1CollectedHeap* _g1h; 5043 RefToScanQueueSet* _queues; 5044 FlexibleWorkGang* _workers; 5045 int _active_workers; 5046 5047 public: 5048 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5049 FlexibleWorkGang* workers, 5050 RefToScanQueueSet *task_queues, 5051 int n_workers) : 5052 _g1h(g1h), 5053 _queues(task_queues), 5054 _workers(workers), 5055 _active_workers(n_workers) 5056 { 5057 assert(n_workers > 0, "shouldn't call this otherwise"); 5058 } 5059 5060 // Executes the given task using concurrent marking worker threads. 5061 virtual void execute(ProcessTask& task); 5062 virtual void execute(EnqueueTask& task); 5063 }; 5064 5065 // Gang task for possibly parallel reference processing 5066 5067 class G1STWRefProcTaskProxy: public AbstractGangTask { 5068 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5069 ProcessTask& _proc_task; 5070 G1CollectedHeap* _g1h; 5071 RefToScanQueueSet *_task_queues; 5072 ParallelTaskTerminator* _terminator; 5073 5074 public: 5075 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5076 G1CollectedHeap* g1h, 5077 RefToScanQueueSet *task_queues, 5078 ParallelTaskTerminator* terminator) : 5079 AbstractGangTask("Process reference objects in parallel"), 5080 _proc_task(proc_task), 5081 _g1h(g1h), 5082 _task_queues(task_queues), 5083 _terminator(terminator) 5084 {} 5085 5086 virtual void work(uint worker_id) { 5087 // The reference processing task executed by a single worker. 5088 ResourceMark rm; 5089 HandleMark hm; 5090 5091 G1STWIsAliveClosure is_alive(_g1h); 5092 5093 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5094 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5095 5096 pss.set_evac_failure_closure(&evac_failure_cl); 5097 5098 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5099 5100 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5101 5102 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5103 5104 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5105 // We also need to mark copied objects. 5106 copy_non_heap_cl = ©_mark_non_heap_cl; 5107 } 5108 5109 // Keep alive closure. 5110 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5111 5112 // Complete GC closure 5113 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5114 5115 // Call the reference processing task's work routine. 5116 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5117 5118 // Note we cannot assert that the refs array is empty here as not all 5119 // of the processing tasks (specifically phase2 - pp2_work) execute 5120 // the complete_gc closure (which ordinarily would drain the queue) so 5121 // the queue may not be empty. 5122 } 5123 }; 5124 5125 // Driver routine for parallel reference processing. 5126 // Creates an instance of the ref processing gang 5127 // task and has the worker threads execute it. 5128 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5129 assert(_workers != NULL, "Need parallel worker threads."); 5130 5131 ParallelTaskTerminator terminator(_active_workers, _queues); 5132 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5133 5134 _g1h->set_par_threads(_active_workers); 5135 _workers->run_task(&proc_task_proxy); 5136 _g1h->set_par_threads(0); 5137 } 5138 5139 // Gang task for parallel reference enqueueing. 5140 5141 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5142 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5143 EnqueueTask& _enq_task; 5144 5145 public: 5146 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5147 AbstractGangTask("Enqueue reference objects in parallel"), 5148 _enq_task(enq_task) 5149 { } 5150 5151 virtual void work(uint worker_id) { 5152 _enq_task.work(worker_id); 5153 } 5154 }; 5155 5156 // Driver routine for parallel reference enqueueing. 5157 // Creates an instance of the ref enqueueing gang 5158 // task and has the worker threads execute it. 5159 5160 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5161 assert(_workers != NULL, "Need parallel worker threads."); 5162 5163 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5164 5165 _g1h->set_par_threads(_active_workers); 5166 _workers->run_task(&enq_task_proxy); 5167 _g1h->set_par_threads(0); 5168 } 5169 5170 // End of weak reference support closures 5171 5172 // Abstract task used to preserve (i.e. copy) any referent objects 5173 // that are in the collection set and are pointed to by reference 5174 // objects discovered by the CM ref processor. 5175 5176 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5177 protected: 5178 G1CollectedHeap* _g1h; 5179 RefToScanQueueSet *_queues; 5180 ParallelTaskTerminator _terminator; 5181 uint _n_workers; 5182 5183 public: 5184 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5185 AbstractGangTask("ParPreserveCMReferents"), 5186 _g1h(g1h), 5187 _queues(task_queues), 5188 _terminator(workers, _queues), 5189 _n_workers(workers) 5190 { } 5191 5192 void work(uint worker_id) { 5193 ResourceMark rm; 5194 HandleMark hm; 5195 5196 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5197 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5198 5199 pss.set_evac_failure_closure(&evac_failure_cl); 5200 5201 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5202 5203 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5204 5205 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5206 5207 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5208 5209 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5210 // We also need to mark copied objects. 5211 copy_non_heap_cl = ©_mark_non_heap_cl; 5212 } 5213 5214 // Is alive closure 5215 G1AlwaysAliveClosure always_alive(_g1h); 5216 5217 // Copying keep alive closure. Applied to referent objects that need 5218 // to be copied. 5219 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5220 5221 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5222 5223 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5224 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5225 5226 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5227 // So this must be true - but assert just in case someone decides to 5228 // change the worker ids. 5229 assert(worker_id < limit, "sanity"); 5230 assert(!rp->discovery_is_atomic(), "check this code"); 5231 5232 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5233 for (uint idx = worker_id; idx < limit; idx += stride) { 5234 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5235 5236 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5237 while (iter.has_next()) { 5238 // Since discovery is not atomic for the CM ref processor, we 5239 // can see some null referent objects. 5240 iter.load_ptrs(DEBUG_ONLY(true)); 5241 oop ref = iter.obj(); 5242 5243 // This will filter nulls. 5244 if (iter.is_referent_alive()) { 5245 iter.make_referent_alive(); 5246 } 5247 iter.move_to_next(); 5248 } 5249 } 5250 5251 // Drain the queue - which may cause stealing 5252 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5253 drain_queue.do_void(); 5254 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5255 assert(pss.queue_is_empty(), "should be"); 5256 } 5257 }; 5258 5259 // Weak Reference processing during an evacuation pause (part 1). 5260 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5261 double ref_proc_start = os::elapsedTime(); 5262 5263 ReferenceProcessor* rp = _ref_processor_stw; 5264 assert(rp->discovery_enabled(), "should have been enabled"); 5265 5266 // Any reference objects, in the collection set, that were 'discovered' 5267 // by the CM ref processor should have already been copied (either by 5268 // applying the external root copy closure to the discovered lists, or 5269 // by following an RSet entry). 5270 // 5271 // But some of the referents, that are in the collection set, that these 5272 // reference objects point to may not have been copied: the STW ref 5273 // processor would have seen that the reference object had already 5274 // been 'discovered' and would have skipped discovering the reference, 5275 // but would not have treated the reference object as a regular oop. 5276 // As a result the copy closure would not have been applied to the 5277 // referent object. 5278 // 5279 // We need to explicitly copy these referent objects - the references 5280 // will be processed at the end of remarking. 5281 // 5282 // We also need to do this copying before we process the reference 5283 // objects discovered by the STW ref processor in case one of these 5284 // referents points to another object which is also referenced by an 5285 // object discovered by the STW ref processor. 5286 5287 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers"); 5288 5289 set_par_threads(no_of_gc_workers); 5290 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5291 no_of_gc_workers, 5292 _task_queues); 5293 5294 workers()->run_task(&keep_cm_referents); 5295 5296 set_par_threads(0); 5297 5298 // Closure to test whether a referent is alive. 5299 G1STWIsAliveClosure is_alive(this); 5300 5301 // Even when parallel reference processing is enabled, the processing 5302 // of JNI refs is serial and performed serially by the current thread 5303 // rather than by a worker. The following PSS will be used for processing 5304 // JNI refs. 5305 5306 // Use only a single queue for this PSS. 5307 G1ParScanThreadState pss(this, 0, NULL); 5308 5309 // We do not embed a reference processor in the copying/scanning 5310 // closures while we're actually processing the discovered 5311 // reference objects. 5312 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5313 5314 pss.set_evac_failure_closure(&evac_failure_cl); 5315 5316 assert(pss.queue_is_empty(), "pre-condition"); 5317 5318 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5319 5320 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5321 5322 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5323 5324 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5325 // We also need to mark copied objects. 5326 copy_non_heap_cl = ©_mark_non_heap_cl; 5327 } 5328 5329 // Keep alive closure. 5330 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss); 5331 5332 // Serial Complete GC closure 5333 G1STWDrainQueueClosure drain_queue(this, &pss); 5334 5335 // Setup the soft refs policy... 5336 rp->setup_policy(false); 5337 5338 ReferenceProcessorStats stats; 5339 if (!rp->processing_is_mt()) { 5340 // Serial reference processing... 5341 stats = rp->process_discovered_references(&is_alive, 5342 &keep_alive, 5343 &drain_queue, 5344 NULL, 5345 _gc_timer_stw, 5346 _gc_tracer_stw->gc_id()); 5347 } else { 5348 // Parallel reference processing 5349 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5350 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5351 5352 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5353 stats = rp->process_discovered_references(&is_alive, 5354 &keep_alive, 5355 &drain_queue, 5356 &par_task_executor, 5357 _gc_timer_stw, 5358 _gc_tracer_stw->gc_id()); 5359 } 5360 5361 _gc_tracer_stw->report_gc_reference_stats(stats); 5362 5363 // We have completed copying any necessary live referent objects. 5364 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5365 5366 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5367 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5368 } 5369 5370 // Weak Reference processing during an evacuation pause (part 2). 5371 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5372 double ref_enq_start = os::elapsedTime(); 5373 5374 ReferenceProcessor* rp = _ref_processor_stw; 5375 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5376 5377 // Now enqueue any remaining on the discovered lists on to 5378 // the pending list. 5379 if (!rp->processing_is_mt()) { 5380 // Serial reference processing... 5381 rp->enqueue_discovered_references(); 5382 } else { 5383 // Parallel reference enqueueing 5384 5385 assert(no_of_gc_workers == workers()->active_workers(), 5386 "Need to reset active workers"); 5387 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5388 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5389 5390 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5391 rp->enqueue_discovered_references(&par_task_executor); 5392 } 5393 5394 rp->verify_no_references_recorded(); 5395 assert(!rp->discovery_enabled(), "should have been disabled"); 5396 5397 // FIXME 5398 // CM's reference processing also cleans up the string and symbol tables. 5399 // Should we do that here also? We could, but it is a serial operation 5400 // and could significantly increase the pause time. 5401 5402 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5403 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5404 } 5405 5406 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5407 _expand_heap_after_alloc_failure = true; 5408 _evacuation_failed = false; 5409 5410 // Should G1EvacuationFailureALot be in effect for this GC? 5411 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5412 5413 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5414 5415 // Disable the hot card cache. 5416 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5417 hot_card_cache->reset_hot_cache_claimed_index(); 5418 hot_card_cache->set_use_cache(false); 5419 5420 const uint n_workers = workers()->active_workers(); 5421 assert(UseDynamicNumberOfGCThreads || 5422 n_workers == workers()->total_workers(), 5423 "If not dynamic should be using all the workers"); 5424 set_par_threads(n_workers); 5425 5426 5427 init_for_evac_failure(NULL); 5428 5429 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5430 double start_par_time_sec = os::elapsedTime(); 5431 double end_par_time_sec; 5432 5433 { 5434 G1RootProcessor root_processor(this); 5435 G1ParTask g1_par_task(this, _task_queues, &root_processor); 5436 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5437 if (g1_policy()->during_initial_mark_pause()) { 5438 ClassLoaderDataGraph::clear_claimed_marks(); 5439 } 5440 5441 // The individual threads will set their evac-failure closures. 5442 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr(); 5443 // These tasks use ShareHeap::_process_strong_tasks 5444 assert(UseDynamicNumberOfGCThreads || 5445 workers()->active_workers() == workers()->total_workers(), 5446 "If not dynamic should be using all the workers"); 5447 workers()->run_task(&g1_par_task); 5448 end_par_time_sec = os::elapsedTime(); 5449 5450 // Closing the inner scope will execute the destructor 5451 // for the G1RootProcessor object. We record the current 5452 // elapsed time before closing the scope so that time 5453 // taken for the destructor is NOT included in the 5454 // reported parallel time. 5455 } 5456 5457 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 5458 5459 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5460 phase_times->record_par_time(par_time_ms); 5461 5462 double code_root_fixup_time_ms = 5463 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5464 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 5465 5466 set_par_threads(0); 5467 5468 // Process any discovered reference objects - we have 5469 // to do this _before_ we retire the GC alloc regions 5470 // as we may have to copy some 'reachable' referent 5471 // objects (and their reachable sub-graphs) that were 5472 // not copied during the pause. 5473 process_discovered_references(n_workers); 5474 5475 if (G1StringDedup::is_enabled()) { 5476 double fixup_start = os::elapsedTime(); 5477 5478 G1STWIsAliveClosure is_alive(this); 5479 G1KeepAliveClosure keep_alive(this); 5480 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times); 5481 5482 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 5483 phase_times->record_string_dedup_fixup_time(fixup_time_ms); 5484 } 5485 5486 _allocator->release_gc_alloc_regions(n_workers, evacuation_info); 5487 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5488 5489 // Reset and re-enable the hot card cache. 5490 // Note the counts for the cards in the regions in the 5491 // collection set are reset when the collection set is freed. 5492 hot_card_cache->reset_hot_cache(); 5493 hot_card_cache->set_use_cache(true); 5494 5495 purge_code_root_memory(); 5496 5497 finalize_for_evac_failure(); 5498 5499 if (evacuation_failed()) { 5500 remove_self_forwarding_pointers(); 5501 5502 // Reset the G1EvacuationFailureALot counters and flags 5503 // Note: the values are reset only when an actual 5504 // evacuation failure occurs. 5505 NOT_PRODUCT(reset_evacuation_should_fail();) 5506 } 5507 5508 // Enqueue any remaining references remaining on the STW 5509 // reference processor's discovered lists. We need to do 5510 // this after the card table is cleaned (and verified) as 5511 // the act of enqueueing entries on to the pending list 5512 // will log these updates (and dirty their associated 5513 // cards). We need these updates logged to update any 5514 // RSets. 5515 enqueue_discovered_references(n_workers); 5516 5517 redirty_logged_cards(); 5518 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5519 } 5520 5521 void G1CollectedHeap::free_region(HeapRegion* hr, 5522 FreeRegionList* free_list, 5523 bool par, 5524 bool locked) { 5525 assert(!hr->is_free(), "the region should not be free"); 5526 assert(!hr->is_empty(), "the region should not be empty"); 5527 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 5528 assert(free_list != NULL, "pre-condition"); 5529 5530 if (G1VerifyBitmaps) { 5531 MemRegion mr(hr->bottom(), hr->end()); 5532 concurrent_mark()->clearRangePrevBitmap(mr); 5533 } 5534 5535 // Clear the card counts for this region. 5536 // Note: we only need to do this if the region is not young 5537 // (since we don't refine cards in young regions). 5538 if (!hr->is_young()) { 5539 _cg1r->hot_card_cache()->reset_card_counts(hr); 5540 } 5541 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5542 free_list->add_ordered(hr); 5543 } 5544 5545 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5546 FreeRegionList* free_list, 5547 bool par) { 5548 assert(hr->is_starts_humongous(), "this is only for starts humongous regions"); 5549 assert(free_list != NULL, "pre-condition"); 5550 5551 size_t hr_capacity = hr->capacity(); 5552 // We need to read this before we make the region non-humongous, 5553 // otherwise the information will be gone. 5554 uint last_index = hr->last_hc_index(); 5555 hr->clear_humongous(); 5556 free_region(hr, free_list, par); 5557 5558 uint i = hr->hrm_index() + 1; 5559 while (i < last_index) { 5560 HeapRegion* curr_hr = region_at(i); 5561 assert(curr_hr->is_continues_humongous(), "invariant"); 5562 curr_hr->clear_humongous(); 5563 free_region(curr_hr, free_list, par); 5564 i += 1; 5565 } 5566 } 5567 5568 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 5569 const HeapRegionSetCount& humongous_regions_removed) { 5570 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5571 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5572 _old_set.bulk_remove(old_regions_removed); 5573 _humongous_set.bulk_remove(humongous_regions_removed); 5574 } 5575 5576 } 5577 5578 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 5579 assert(list != NULL, "list can't be null"); 5580 if (!list->is_empty()) { 5581 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5582 _hrm.insert_list_into_free_list(list); 5583 } 5584 } 5585 5586 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 5587 _allocator->decrease_used(bytes); 5588 } 5589 5590 class G1ParCleanupCTTask : public AbstractGangTask { 5591 G1SATBCardTableModRefBS* _ct_bs; 5592 G1CollectedHeap* _g1h; 5593 HeapRegion* volatile _su_head; 5594 public: 5595 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 5596 G1CollectedHeap* g1h) : 5597 AbstractGangTask("G1 Par Cleanup CT Task"), 5598 _ct_bs(ct_bs), _g1h(g1h) { } 5599 5600 void work(uint worker_id) { 5601 HeapRegion* r; 5602 while (r = _g1h->pop_dirty_cards_region()) { 5603 clear_cards(r); 5604 } 5605 } 5606 5607 void clear_cards(HeapRegion* r) { 5608 // Cards of the survivors should have already been dirtied. 5609 if (!r->is_survivor()) { 5610 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5611 } 5612 } 5613 }; 5614 5615 #ifndef PRODUCT 5616 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5617 G1CollectedHeap* _g1h; 5618 G1SATBCardTableModRefBS* _ct_bs; 5619 public: 5620 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 5621 : _g1h(g1h), _ct_bs(ct_bs) { } 5622 virtual bool doHeapRegion(HeapRegion* r) { 5623 if (r->is_survivor()) { 5624 _g1h->verify_dirty_region(r); 5625 } else { 5626 _g1h->verify_not_dirty_region(r); 5627 } 5628 return false; 5629 } 5630 }; 5631 5632 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5633 // All of the region should be clean. 5634 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5635 MemRegion mr(hr->bottom(), hr->end()); 5636 ct_bs->verify_not_dirty_region(mr); 5637 } 5638 5639 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5640 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5641 // dirty allocated blocks as they allocate them. The thread that 5642 // retires each region and replaces it with a new one will do a 5643 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5644 // not dirty that area (one less thing to have to do while holding 5645 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5646 // is dirty. 5647 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5648 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5649 if (hr->is_young()) { 5650 ct_bs->verify_g1_young_region(mr); 5651 } else { 5652 ct_bs->verify_dirty_region(mr); 5653 } 5654 } 5655 5656 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5657 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5658 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5659 verify_dirty_region(hr); 5660 } 5661 } 5662 5663 void G1CollectedHeap::verify_dirty_young_regions() { 5664 verify_dirty_young_list(_young_list->first_region()); 5665 } 5666 5667 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 5668 HeapWord* tams, HeapWord* end) { 5669 guarantee(tams <= end, 5670 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end)); 5671 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 5672 if (result < end) { 5673 gclog_or_tty->cr(); 5674 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT, 5675 bitmap_name, result); 5676 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT, 5677 bitmap_name, tams, end); 5678 return false; 5679 } 5680 return true; 5681 } 5682 5683 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 5684 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 5685 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 5686 5687 HeapWord* bottom = hr->bottom(); 5688 HeapWord* ptams = hr->prev_top_at_mark_start(); 5689 HeapWord* ntams = hr->next_top_at_mark_start(); 5690 HeapWord* end = hr->end(); 5691 5692 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 5693 5694 bool res_n = true; 5695 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 5696 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 5697 // if we happen to be in that state. 5698 if (mark_in_progress() || !_cmThread->in_progress()) { 5699 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 5700 } 5701 if (!res_p || !res_n) { 5702 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT, 5703 HR_FORMAT_PARAMS(hr)); 5704 gclog_or_tty->print_cr("#### Caller: %s", caller); 5705 return false; 5706 } 5707 return true; 5708 } 5709 5710 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 5711 if (!G1VerifyBitmaps) return; 5712 5713 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 5714 } 5715 5716 class G1VerifyBitmapClosure : public HeapRegionClosure { 5717 private: 5718 const char* _caller; 5719 G1CollectedHeap* _g1h; 5720 bool _failures; 5721 5722 public: 5723 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 5724 _caller(caller), _g1h(g1h), _failures(false) { } 5725 5726 bool failures() { return _failures; } 5727 5728 virtual bool doHeapRegion(HeapRegion* hr) { 5729 if (hr->is_continues_humongous()) return false; 5730 5731 bool result = _g1h->verify_bitmaps(_caller, hr); 5732 if (!result) { 5733 _failures = true; 5734 } 5735 return false; 5736 } 5737 }; 5738 5739 void G1CollectedHeap::check_bitmaps(const char* caller) { 5740 if (!G1VerifyBitmaps) return; 5741 5742 G1VerifyBitmapClosure cl(caller, this); 5743 heap_region_iterate(&cl); 5744 guarantee(!cl.failures(), "bitmap verification"); 5745 } 5746 5747 class G1CheckCSetFastTableClosure : public HeapRegionClosure { 5748 private: 5749 bool _failures; 5750 public: 5751 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { } 5752 5753 virtual bool doHeapRegion(HeapRegion* hr) { 5754 uint i = hr->hrm_index(); 5755 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i); 5756 if (hr->is_humongous()) { 5757 if (hr->in_collection_set()) { 5758 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i); 5759 _failures = true; 5760 return true; 5761 } 5762 if (cset_state.is_in_cset()) { 5763 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i); 5764 _failures = true; 5765 return true; 5766 } 5767 if (hr->is_continues_humongous() && cset_state.is_humongous()) { 5768 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i); 5769 _failures = true; 5770 return true; 5771 } 5772 } else { 5773 if (cset_state.is_humongous()) { 5774 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i); 5775 _failures = true; 5776 return true; 5777 } 5778 if (hr->in_collection_set() != cset_state.is_in_cset()) { 5779 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u", 5780 hr->in_collection_set(), cset_state.value(), i); 5781 _failures = true; 5782 return true; 5783 } 5784 if (cset_state.is_in_cset()) { 5785 if (hr->is_young() != (cset_state.is_young())) { 5786 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u", 5787 hr->is_young(), cset_state.value(), i); 5788 _failures = true; 5789 return true; 5790 } 5791 if (hr->is_old() != (cset_state.is_old())) { 5792 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u", 5793 hr->is_old(), cset_state.value(), i); 5794 _failures = true; 5795 return true; 5796 } 5797 } 5798 } 5799 return false; 5800 } 5801 5802 bool failures() const { return _failures; } 5803 }; 5804 5805 bool G1CollectedHeap::check_cset_fast_test() { 5806 G1CheckCSetFastTableClosure cl; 5807 _hrm.iterate(&cl); 5808 return !cl.failures(); 5809 } 5810 #endif // PRODUCT 5811 5812 void G1CollectedHeap::cleanUpCardTable() { 5813 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5814 double start = os::elapsedTime(); 5815 5816 { 5817 // Iterate over the dirty cards region list. 5818 G1ParCleanupCTTask cleanup_task(ct_bs, this); 5819 5820 set_par_threads(); 5821 workers()->run_task(&cleanup_task); 5822 set_par_threads(0); 5823 #ifndef PRODUCT 5824 if (G1VerifyCTCleanup || VerifyAfterGC) { 5825 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 5826 heap_region_iterate(&cleanup_verifier); 5827 } 5828 #endif 5829 } 5830 5831 double elapsed = os::elapsedTime() - start; 5832 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 5833 } 5834 5835 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 5836 size_t pre_used = 0; 5837 FreeRegionList local_free_list("Local List for CSet Freeing"); 5838 5839 double young_time_ms = 0.0; 5840 double non_young_time_ms = 0.0; 5841 5842 // Since the collection set is a superset of the the young list, 5843 // all we need to do to clear the young list is clear its 5844 // head and length, and unlink any young regions in the code below 5845 _young_list->clear(); 5846 5847 G1CollectorPolicy* policy = g1_policy(); 5848 5849 double start_sec = os::elapsedTime(); 5850 bool non_young = true; 5851 5852 HeapRegion* cur = cs_head; 5853 int age_bound = -1; 5854 size_t rs_lengths = 0; 5855 5856 while (cur != NULL) { 5857 assert(!is_on_master_free_list(cur), "sanity"); 5858 if (non_young) { 5859 if (cur->is_young()) { 5860 double end_sec = os::elapsedTime(); 5861 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5862 non_young_time_ms += elapsed_ms; 5863 5864 start_sec = os::elapsedTime(); 5865 non_young = false; 5866 } 5867 } else { 5868 if (!cur->is_young()) { 5869 double end_sec = os::elapsedTime(); 5870 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5871 young_time_ms += elapsed_ms; 5872 5873 start_sec = os::elapsedTime(); 5874 non_young = true; 5875 } 5876 } 5877 5878 rs_lengths += cur->rem_set()->occupied_locked(); 5879 5880 HeapRegion* next = cur->next_in_collection_set(); 5881 assert(cur->in_collection_set(), "bad CS"); 5882 cur->set_next_in_collection_set(NULL); 5883 clear_in_cset(cur); 5884 5885 if (cur->is_young()) { 5886 int index = cur->young_index_in_cset(); 5887 assert(index != -1, "invariant"); 5888 assert((uint) index < policy->young_cset_region_length(), "invariant"); 5889 size_t words_survived = _surviving_young_words[index]; 5890 cur->record_surv_words_in_group(words_survived); 5891 5892 // At this point the we have 'popped' cur from the collection set 5893 // (linked via next_in_collection_set()) but it is still in the 5894 // young list (linked via next_young_region()). Clear the 5895 // _next_young_region field. 5896 cur->set_next_young_region(NULL); 5897 } else { 5898 int index = cur->young_index_in_cset(); 5899 assert(index == -1, "invariant"); 5900 } 5901 5902 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 5903 (!cur->is_young() && cur->young_index_in_cset() == -1), 5904 "invariant" ); 5905 5906 if (!cur->evacuation_failed()) { 5907 MemRegion used_mr = cur->used_region(); 5908 5909 // And the region is empty. 5910 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 5911 pre_used += cur->used(); 5912 free_region(cur, &local_free_list, false /* par */, true /* locked */); 5913 } else { 5914 cur->uninstall_surv_rate_group(); 5915 if (cur->is_young()) { 5916 cur->set_young_index_in_cset(-1); 5917 } 5918 cur->set_evacuation_failed(false); 5919 // The region is now considered to be old. 5920 cur->set_old(); 5921 _old_set.add(cur); 5922 evacuation_info.increment_collectionset_used_after(cur->used()); 5923 } 5924 cur = next; 5925 } 5926 5927 evacuation_info.set_regions_freed(local_free_list.length()); 5928 policy->record_max_rs_lengths(rs_lengths); 5929 policy->cset_regions_freed(); 5930 5931 double end_sec = os::elapsedTime(); 5932 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5933 5934 if (non_young) { 5935 non_young_time_ms += elapsed_ms; 5936 } else { 5937 young_time_ms += elapsed_ms; 5938 } 5939 5940 prepend_to_freelist(&local_free_list); 5941 decrement_summary_bytes(pre_used); 5942 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 5943 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 5944 } 5945 5946 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 5947 private: 5948 FreeRegionList* _free_region_list; 5949 HeapRegionSet* _proxy_set; 5950 HeapRegionSetCount _humongous_regions_removed; 5951 size_t _freed_bytes; 5952 public: 5953 5954 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 5955 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 5956 } 5957 5958 virtual bool doHeapRegion(HeapRegion* r) { 5959 if (!r->is_starts_humongous()) { 5960 return false; 5961 } 5962 5963 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 5964 5965 oop obj = (oop)r->bottom(); 5966 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 5967 5968 // The following checks whether the humongous object is live are sufficient. 5969 // The main additional check (in addition to having a reference from the roots 5970 // or the young gen) is whether the humongous object has a remembered set entry. 5971 // 5972 // A humongous object cannot be live if there is no remembered set for it 5973 // because: 5974 // - there can be no references from within humongous starts regions referencing 5975 // the object because we never allocate other objects into them. 5976 // (I.e. there are no intra-region references that may be missed by the 5977 // remembered set) 5978 // - as soon there is a remembered set entry to the humongous starts region 5979 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 5980 // until the end of a concurrent mark. 5981 // 5982 // It is not required to check whether the object has been found dead by marking 5983 // or not, in fact it would prevent reclamation within a concurrent cycle, as 5984 // all objects allocated during that time are considered live. 5985 // SATB marking is even more conservative than the remembered set. 5986 // So if at this point in the collection there is no remembered set entry, 5987 // nobody has a reference to it. 5988 // At the start of collection we flush all refinement logs, and remembered sets 5989 // are completely up-to-date wrt to references to the humongous object. 5990 // 5991 // Other implementation considerations: 5992 // - never consider object arrays at this time because they would pose 5993 // considerable effort for cleaning up the the remembered sets. This is 5994 // required because stale remembered sets might reference locations that 5995 // are currently allocated into. 5996 uint region_idx = r->hrm_index(); 5997 if (g1h->humongous_is_live(region_idx) || 5998 g1h->humongous_region_is_always_live(region_idx)) { 5999 6000 if (G1TraceEagerReclaimHumongousObjects) { 6001 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", 6002 region_idx, 6003 obj->size()*HeapWordSize, 6004 r->bottom(), 6005 r->region_num(), 6006 r->rem_set()->occupied(), 6007 r->rem_set()->strong_code_roots_list_length(), 6008 next_bitmap->isMarked(r->bottom()), 6009 g1h->humongous_is_live(region_idx), 6010 obj->is_objArray() 6011 ); 6012 } 6013 6014 return false; 6015 } 6016 6017 guarantee(!obj->is_objArray(), 6018 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.", 6019 r->bottom())); 6020 6021 if (G1TraceEagerReclaimHumongousObjects) { 6022 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", 6023 region_idx, 6024 obj->size()*HeapWordSize, 6025 r->bottom(), 6026 r->region_num(), 6027 r->rem_set()->occupied(), 6028 r->rem_set()->strong_code_roots_list_length(), 6029 next_bitmap->isMarked(r->bottom()), 6030 g1h->humongous_is_live(region_idx), 6031 obj->is_objArray() 6032 ); 6033 } 6034 // Need to clear mark bit of the humongous object if already set. 6035 if (next_bitmap->isMarked(r->bottom())) { 6036 next_bitmap->clear(r->bottom()); 6037 } 6038 _freed_bytes += r->used(); 6039 r->set_containing_set(NULL); 6040 _humongous_regions_removed.increment(1u, r->capacity()); 6041 g1h->free_humongous_region(r, _free_region_list, false); 6042 6043 return false; 6044 } 6045 6046 HeapRegionSetCount& humongous_free_count() { 6047 return _humongous_regions_removed; 6048 } 6049 6050 size_t bytes_freed() const { 6051 return _freed_bytes; 6052 } 6053 6054 size_t humongous_reclaimed() const { 6055 return _humongous_regions_removed.length(); 6056 } 6057 }; 6058 6059 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 6060 assert_at_safepoint(true); 6061 6062 if (!G1EagerReclaimHumongousObjects || 6063 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) { 6064 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 6065 return; 6066 } 6067 6068 double start_time = os::elapsedTime(); 6069 6070 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 6071 6072 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 6073 heap_region_iterate(&cl); 6074 6075 HeapRegionSetCount empty_set; 6076 remove_from_old_sets(empty_set, cl.humongous_free_count()); 6077 6078 G1HRPrinter* hr_printer = _g1h->hr_printer(); 6079 if (hr_printer->is_active()) { 6080 FreeRegionListIterator iter(&local_cleanup_list); 6081 while (iter.more_available()) { 6082 HeapRegion* hr = iter.get_next(); 6083 hr_printer->cleanup(hr); 6084 } 6085 } 6086 6087 prepend_to_freelist(&local_cleanup_list); 6088 decrement_summary_bytes(cl.bytes_freed()); 6089 6090 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 6091 cl.humongous_reclaimed()); 6092 } 6093 6094 // This routine is similar to the above but does not record 6095 // any policy statistics or update free lists; we are abandoning 6096 // the current incremental collection set in preparation of a 6097 // full collection. After the full GC we will start to build up 6098 // the incremental collection set again. 6099 // This is only called when we're doing a full collection 6100 // and is immediately followed by the tearing down of the young list. 6101 6102 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6103 HeapRegion* cur = cs_head; 6104 6105 while (cur != NULL) { 6106 HeapRegion* next = cur->next_in_collection_set(); 6107 assert(cur->in_collection_set(), "bad CS"); 6108 cur->set_next_in_collection_set(NULL); 6109 clear_in_cset(cur); 6110 cur->set_young_index_in_cset(-1); 6111 cur = next; 6112 } 6113 } 6114 6115 void G1CollectedHeap::set_free_regions_coming() { 6116 if (G1ConcRegionFreeingVerbose) { 6117 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6118 "setting free regions coming"); 6119 } 6120 6121 assert(!free_regions_coming(), "pre-condition"); 6122 _free_regions_coming = true; 6123 } 6124 6125 void G1CollectedHeap::reset_free_regions_coming() { 6126 assert(free_regions_coming(), "pre-condition"); 6127 6128 { 6129 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6130 _free_regions_coming = false; 6131 SecondaryFreeList_lock->notify_all(); 6132 } 6133 6134 if (G1ConcRegionFreeingVerbose) { 6135 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6136 "reset free regions coming"); 6137 } 6138 } 6139 6140 void G1CollectedHeap::wait_while_free_regions_coming() { 6141 // Most of the time we won't have to wait, so let's do a quick test 6142 // first before we take the lock. 6143 if (!free_regions_coming()) { 6144 return; 6145 } 6146 6147 if (G1ConcRegionFreeingVerbose) { 6148 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6149 "waiting for free regions"); 6150 } 6151 6152 { 6153 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6154 while (free_regions_coming()) { 6155 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6156 } 6157 } 6158 6159 if (G1ConcRegionFreeingVerbose) { 6160 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6161 "done waiting for free regions"); 6162 } 6163 } 6164 6165 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6166 _young_list->push_region(hr); 6167 } 6168 6169 class NoYoungRegionsClosure: public HeapRegionClosure { 6170 private: 6171 bool _success; 6172 public: 6173 NoYoungRegionsClosure() : _success(true) { } 6174 bool doHeapRegion(HeapRegion* r) { 6175 if (r->is_young()) { 6176 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6177 r->bottom(), r->end()); 6178 _success = false; 6179 } 6180 return false; 6181 } 6182 bool success() { return _success; } 6183 }; 6184 6185 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6186 bool ret = _young_list->check_list_empty(check_sample); 6187 6188 if (check_heap) { 6189 NoYoungRegionsClosure closure; 6190 heap_region_iterate(&closure); 6191 ret = ret && closure.success(); 6192 } 6193 6194 return ret; 6195 } 6196 6197 class TearDownRegionSetsClosure : public HeapRegionClosure { 6198 private: 6199 HeapRegionSet *_old_set; 6200 6201 public: 6202 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6203 6204 bool doHeapRegion(HeapRegion* r) { 6205 if (r->is_old()) { 6206 _old_set->remove(r); 6207 } else { 6208 // We ignore free regions, we'll empty the free list afterwards. 6209 // We ignore young regions, we'll empty the young list afterwards. 6210 // We ignore humongous regions, we're not tearing down the 6211 // humongous regions set. 6212 assert(r->is_free() || r->is_young() || r->is_humongous(), 6213 "it cannot be another type"); 6214 } 6215 return false; 6216 } 6217 6218 ~TearDownRegionSetsClosure() { 6219 assert(_old_set->is_empty(), "post-condition"); 6220 } 6221 }; 6222 6223 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6224 assert_at_safepoint(true /* should_be_vm_thread */); 6225 6226 if (!free_list_only) { 6227 TearDownRegionSetsClosure cl(&_old_set); 6228 heap_region_iterate(&cl); 6229 6230 // Note that emptying the _young_list is postponed and instead done as 6231 // the first step when rebuilding the regions sets again. The reason for 6232 // this is that during a full GC string deduplication needs to know if 6233 // a collected region was young or old when the full GC was initiated. 6234 } 6235 _hrm.remove_all_free_regions(); 6236 } 6237 6238 class RebuildRegionSetsClosure : public HeapRegionClosure { 6239 private: 6240 bool _free_list_only; 6241 HeapRegionSet* _old_set; 6242 HeapRegionManager* _hrm; 6243 size_t _total_used; 6244 6245 public: 6246 RebuildRegionSetsClosure(bool free_list_only, 6247 HeapRegionSet* old_set, HeapRegionManager* hrm) : 6248 _free_list_only(free_list_only), 6249 _old_set(old_set), _hrm(hrm), _total_used(0) { 6250 assert(_hrm->num_free_regions() == 0, "pre-condition"); 6251 if (!free_list_only) { 6252 assert(_old_set->is_empty(), "pre-condition"); 6253 } 6254 } 6255 6256 bool doHeapRegion(HeapRegion* r) { 6257 if (r->is_continues_humongous()) { 6258 return false; 6259 } 6260 6261 if (r->is_empty()) { 6262 // Add free regions to the free list 6263 r->set_free(); 6264 r->set_allocation_context(AllocationContext::system()); 6265 _hrm->insert_into_free_list(r); 6266 } else if (!_free_list_only) { 6267 assert(!r->is_young(), "we should not come across young regions"); 6268 6269 if (r->is_humongous()) { 6270 // We ignore humongous regions, we left the humongous set unchanged 6271 } else { 6272 // Objects that were compacted would have ended up on regions 6273 // that were previously old or free. 6274 assert(r->is_free() || r->is_old(), "invariant"); 6275 // We now consider them old, so register as such. 6276 r->set_old(); 6277 _old_set->add(r); 6278 } 6279 _total_used += r->used(); 6280 } 6281 6282 return false; 6283 } 6284 6285 size_t total_used() { 6286 return _total_used; 6287 } 6288 }; 6289 6290 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6291 assert_at_safepoint(true /* should_be_vm_thread */); 6292 6293 if (!free_list_only) { 6294 _young_list->empty_list(); 6295 } 6296 6297 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 6298 heap_region_iterate(&cl); 6299 6300 if (!free_list_only) { 6301 _allocator->set_used(cl.total_used()); 6302 } 6303 assert(_allocator->used_unlocked() == recalculate_used(), 6304 err_msg("inconsistent _allocator->used_unlocked(), " 6305 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6306 _allocator->used_unlocked(), recalculate_used())); 6307 } 6308 6309 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6310 _refine_cte_cl->set_concurrent(concurrent); 6311 } 6312 6313 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6314 HeapRegion* hr = heap_region_containing(p); 6315 return hr->is_in(p); 6316 } 6317 6318 // Methods for the mutator alloc region 6319 6320 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6321 bool force) { 6322 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6323 assert(!force || g1_policy()->can_expand_young_list(), 6324 "if force is true we should be able to expand the young list"); 6325 bool young_list_full = g1_policy()->is_young_list_full(); 6326 if (force || !young_list_full) { 6327 HeapRegion* new_alloc_region = new_region(word_size, 6328 false /* is_old */, 6329 false /* do_expand */); 6330 if (new_alloc_region != NULL) { 6331 set_region_short_lived_locked(new_alloc_region); 6332 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6333 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6334 return new_alloc_region; 6335 } 6336 } 6337 return NULL; 6338 } 6339 6340 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6341 size_t allocated_bytes) { 6342 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6343 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 6344 6345 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6346 _allocator->increase_used(allocated_bytes); 6347 _hr_printer.retire(alloc_region); 6348 // We update the eden sizes here, when the region is retired, 6349 // instead of when it's allocated, since this is the point that its 6350 // used space has been recored in _summary_bytes_used. 6351 g1mm()->update_eden_size(); 6352 } 6353 6354 void G1CollectedHeap::set_par_threads() { 6355 // Don't change the number of workers. Use the value previously set 6356 // in the workgroup. 6357 uint n_workers = workers()->active_workers(); 6358 assert(UseDynamicNumberOfGCThreads || 6359 n_workers == workers()->total_workers(), 6360 "Otherwise should be using the total number of workers"); 6361 if (n_workers == 0) { 6362 assert(false, "Should have been set in prior evacuation pause."); 6363 n_workers = ParallelGCThreads; 6364 workers()->set_active_workers(n_workers); 6365 } 6366 set_par_threads(n_workers); 6367 } 6368 6369 // Methods for the GC alloc regions 6370 6371 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6372 uint count, 6373 InCSetState dest) { 6374 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6375 6376 if (count < g1_policy()->max_regions(dest)) { 6377 const bool is_survivor = (dest.is_young()); 6378 HeapRegion* new_alloc_region = new_region(word_size, 6379 !is_survivor, 6380 true /* do_expand */); 6381 if (new_alloc_region != NULL) { 6382 // We really only need to do this for old regions given that we 6383 // should never scan survivors. But it doesn't hurt to do it 6384 // for survivors too. 6385 new_alloc_region->record_timestamp(); 6386 if (is_survivor) { 6387 new_alloc_region->set_survivor(); 6388 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6389 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6390 } else { 6391 new_alloc_region->set_old(); 6392 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6393 check_bitmaps("Old Region Allocation", new_alloc_region); 6394 } 6395 bool during_im = g1_policy()->during_initial_mark_pause(); 6396 new_alloc_region->note_start_of_copying(during_im); 6397 return new_alloc_region; 6398 } 6399 } 6400 return NULL; 6401 } 6402 6403 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6404 size_t allocated_bytes, 6405 InCSetState dest) { 6406 bool during_im = g1_policy()->during_initial_mark_pause(); 6407 alloc_region->note_end_of_copying(during_im); 6408 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6409 if (dest.is_young()) { 6410 young_list()->add_survivor_region(alloc_region); 6411 } else { 6412 _old_set.add(alloc_region); 6413 } 6414 _hr_printer.retire(alloc_region); 6415 } 6416 6417 // Heap region set verification 6418 6419 class VerifyRegionListsClosure : public HeapRegionClosure { 6420 private: 6421 HeapRegionSet* _old_set; 6422 HeapRegionSet* _humongous_set; 6423 HeapRegionManager* _hrm; 6424 6425 public: 6426 HeapRegionSetCount _old_count; 6427 HeapRegionSetCount _humongous_count; 6428 HeapRegionSetCount _free_count; 6429 6430 VerifyRegionListsClosure(HeapRegionSet* old_set, 6431 HeapRegionSet* humongous_set, 6432 HeapRegionManager* hrm) : 6433 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm), 6434 _old_count(), _humongous_count(), _free_count(){ } 6435 6436 bool doHeapRegion(HeapRegion* hr) { 6437 if (hr->is_continues_humongous()) { 6438 return false; 6439 } 6440 6441 if (hr->is_young()) { 6442 // TODO 6443 } else if (hr->is_starts_humongous()) { 6444 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index())); 6445 _humongous_count.increment(1u, hr->capacity()); 6446 } else if (hr->is_empty()) { 6447 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index())); 6448 _free_count.increment(1u, hr->capacity()); 6449 } else if (hr->is_old()) { 6450 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index())); 6451 _old_count.increment(1u, hr->capacity()); 6452 } else { 6453 ShouldNotReachHere(); 6454 } 6455 return false; 6456 } 6457 6458 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) { 6459 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 6460 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6461 old_set->total_capacity_bytes(), _old_count.capacity())); 6462 6463 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 6464 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6465 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 6466 6467 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())); 6468 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6469 free_list->total_capacity_bytes(), _free_count.capacity())); 6470 } 6471 }; 6472 6473 void G1CollectedHeap::verify_region_sets() { 6474 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6475 6476 // First, check the explicit lists. 6477 _hrm.verify(); 6478 { 6479 // Given that a concurrent operation might be adding regions to 6480 // the secondary free list we have to take the lock before 6481 // verifying it. 6482 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6483 _secondary_free_list.verify_list(); 6484 } 6485 6486 // If a concurrent region freeing operation is in progress it will 6487 // be difficult to correctly attributed any free regions we come 6488 // across to the correct free list given that they might belong to 6489 // one of several (free_list, secondary_free_list, any local lists, 6490 // etc.). So, if that's the case we will skip the rest of the 6491 // verification operation. Alternatively, waiting for the concurrent 6492 // operation to complete will have a non-trivial effect on the GC's 6493 // operation (no concurrent operation will last longer than the 6494 // interval between two calls to verification) and it might hide 6495 // any issues that we would like to catch during testing. 6496 if (free_regions_coming()) { 6497 return; 6498 } 6499 6500 // Make sure we append the secondary_free_list on the free_list so 6501 // that all free regions we will come across can be safely 6502 // attributed to the free_list. 6503 append_secondary_free_list_if_not_empty_with_lock(); 6504 6505 // Finally, make sure that the region accounting in the lists is 6506 // consistent with what we see in the heap. 6507 6508 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm); 6509 heap_region_iterate(&cl); 6510 cl.verify_counts(&_old_set, &_humongous_set, &_hrm); 6511 } 6512 6513 // Optimized nmethod scanning 6514 6515 class RegisterNMethodOopClosure: public OopClosure { 6516 G1CollectedHeap* _g1h; 6517 nmethod* _nm; 6518 6519 template <class T> void do_oop_work(T* p) { 6520 T heap_oop = oopDesc::load_heap_oop(p); 6521 if (!oopDesc::is_null(heap_oop)) { 6522 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6523 HeapRegion* hr = _g1h->heap_region_containing(obj); 6524 assert(!hr->is_continues_humongous(), 6525 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6526 " starting at "HR_FORMAT, 6527 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6528 6529 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 6530 hr->add_strong_code_root_locked(_nm); 6531 } 6532 } 6533 6534 public: 6535 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6536 _g1h(g1h), _nm(nm) {} 6537 6538 void do_oop(oop* p) { do_oop_work(p); } 6539 void do_oop(narrowOop* p) { do_oop_work(p); } 6540 }; 6541 6542 class UnregisterNMethodOopClosure: 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 remove 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 hr->remove_strong_code_root(_nm); 6557 } 6558 } 6559 6560 public: 6561 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6562 _g1h(g1h), _nm(nm) {} 6563 6564 void do_oop(oop* p) { do_oop_work(p); } 6565 void do_oop(narrowOop* p) { do_oop_work(p); } 6566 }; 6567 6568 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6569 CollectedHeap::register_nmethod(nm); 6570 6571 guarantee(nm != NULL, "sanity"); 6572 RegisterNMethodOopClosure reg_cl(this, nm); 6573 nm->oops_do(®_cl); 6574 } 6575 6576 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6577 CollectedHeap::unregister_nmethod(nm); 6578 6579 guarantee(nm != NULL, "sanity"); 6580 UnregisterNMethodOopClosure reg_cl(this, nm); 6581 nm->oops_do(®_cl, true); 6582 } 6583 6584 void G1CollectedHeap::purge_code_root_memory() { 6585 double purge_start = os::elapsedTime(); 6586 G1CodeRootSet::purge(); 6587 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6588 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6589 } 6590 6591 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6592 G1CollectedHeap* _g1h; 6593 6594 public: 6595 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6596 _g1h(g1h) {} 6597 6598 void do_code_blob(CodeBlob* cb) { 6599 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6600 if (nm == NULL) { 6601 return; 6602 } 6603 6604 if (ScavengeRootsInCode) { 6605 _g1h->register_nmethod(nm); 6606 } 6607 } 6608 }; 6609 6610 void G1CollectedHeap::rebuild_strong_code_roots() { 6611 RebuildStrongCodeRootClosure blob_cl(this); 6612 CodeCache::blobs_do(&blob_cl); 6613 }