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 set_barrier_set(bs); 1858 1859 // Also create a G1 rem set. 1860 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 1861 1862 // Carve out the G1 part of the heap. 1863 1864 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1865 G1RegionToSpaceMapper* heap_storage = 1866 G1RegionToSpaceMapper::create_mapper(g1_rs, 1867 UseLargePages ? os::large_page_size() : os::vm_page_size(), 1868 HeapRegion::GrainBytes, 1869 1, 1870 mtJavaHeap); 1871 heap_storage->set_mapping_changed_listener(&_listener); 1872 1873 // Reserve space for the block offset table. We do not support automatic uncommit 1874 // for the card table at this time. BOT only. 1875 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize)); 1876 G1RegionToSpaceMapper* bot_storage = 1877 G1RegionToSpaceMapper::create_mapper(bot_rs, 1878 os::vm_page_size(), 1879 HeapRegion::GrainBytes, 1880 G1BlockOffsetSharedArray::N_bytes, 1881 mtGC); 1882 1883 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 1884 G1RegionToSpaceMapper* cardtable_storage = 1885 G1RegionToSpaceMapper::create_mapper(cardtable_rs, 1886 os::vm_page_size(), 1887 HeapRegion::GrainBytes, 1888 G1BlockOffsetSharedArray::N_bytes, 1889 mtGC); 1890 1891 // Reserve space for the card counts table. 1892 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize)); 1893 G1RegionToSpaceMapper* card_counts_storage = 1894 G1RegionToSpaceMapper::create_mapper(card_counts_rs, 1895 os::vm_page_size(), 1896 HeapRegion::GrainBytes, 1897 G1BlockOffsetSharedArray::N_bytes, 1898 mtGC); 1899 1900 // Reserve space for prev and next bitmap. 1901 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); 1902 1903 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size)); 1904 G1RegionToSpaceMapper* prev_bitmap_storage = 1905 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs, 1906 os::vm_page_size(), 1907 HeapRegion::GrainBytes, 1908 CMBitMap::mark_distance(), 1909 mtGC); 1910 1911 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size)); 1912 G1RegionToSpaceMapper* next_bitmap_storage = 1913 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs, 1914 os::vm_page_size(), 1915 HeapRegion::GrainBytes, 1916 CMBitMap::mark_distance(), 1917 mtGC); 1918 1919 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1920 g1_barrier_set()->initialize(cardtable_storage); 1921 // Do later initialization work for concurrent refinement. 1922 _cg1r->init(card_counts_storage); 1923 1924 // 6843694 - ensure that the maximum region index can fit 1925 // in the remembered set structures. 1926 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1927 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1928 1929 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1930 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1931 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1932 "too many cards per region"); 1933 1934 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1935 1936 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage); 1937 1938 _g1h = this; 1939 1940 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes); 1941 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes); 1942 1943 // Create the ConcurrentMark data structure and thread. 1944 // (Must do this late, so that "max_regions" is defined.) 1945 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1946 if (_cm == NULL || !_cm->completed_initialization()) { 1947 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 1948 return JNI_ENOMEM; 1949 } 1950 _cmThread = _cm->cmThread(); 1951 1952 // Initialize the from_card cache structure of HeapRegionRemSet. 1953 HeapRegionRemSet::init_heap(max_regions()); 1954 1955 // Now expand into the initial heap size. 1956 if (!expand(init_byte_size)) { 1957 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1958 return JNI_ENOMEM; 1959 } 1960 1961 // Perform any initialization actions delegated to the policy. 1962 g1_policy()->init(); 1963 1964 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 1965 SATB_Q_FL_lock, 1966 G1SATBProcessCompletedThreshold, 1967 Shared_SATB_Q_lock); 1968 1969 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 1970 DirtyCardQ_CBL_mon, 1971 DirtyCardQ_FL_lock, 1972 concurrent_g1_refine()->yellow_zone(), 1973 concurrent_g1_refine()->red_zone(), 1974 Shared_DirtyCardQ_lock); 1975 1976 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 1977 DirtyCardQ_CBL_mon, 1978 DirtyCardQ_FL_lock, 1979 -1, // never trigger processing 1980 -1, // no limit on length 1981 Shared_DirtyCardQ_lock, 1982 &JavaThread::dirty_card_queue_set()); 1983 1984 // Initialize the card queue set used to hold cards containing 1985 // references into the collection set. 1986 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 1987 DirtyCardQ_CBL_mon, 1988 DirtyCardQ_FL_lock, 1989 -1, // never trigger processing 1990 -1, // no limit on length 1991 Shared_DirtyCardQ_lock, 1992 &JavaThread::dirty_card_queue_set()); 1993 1994 // Here we allocate the dummy HeapRegion that is required by the 1995 // G1AllocRegion class. 1996 HeapRegion* dummy_region = _hrm.get_dummy_region(); 1997 1998 // We'll re-use the same region whether the alloc region will 1999 // require BOT updates or not and, if it doesn't, then a non-young 2000 // region will complain that it cannot support allocations without 2001 // BOT updates. So we'll tag the dummy region as eden to avoid that. 2002 dummy_region->set_eden(); 2003 // Make sure it's full. 2004 dummy_region->set_top(dummy_region->end()); 2005 G1AllocRegion::setup(this, dummy_region); 2006 2007 _allocator->init_mutator_alloc_region(); 2008 2009 // Do create of the monitoring and management support so that 2010 // values in the heap have been properly initialized. 2011 _g1mm = new G1MonitoringSupport(this); 2012 2013 G1StringDedup::initialize(); 2014 2015 return JNI_OK; 2016 } 2017 2018 void G1CollectedHeap::stop() { 2019 // Stop all concurrent threads. We do this to make sure these threads 2020 // do not continue to execute and access resources (e.g. gclog_or_tty) 2021 // that are destroyed during shutdown. 2022 _cg1r->stop(); 2023 _cmThread->stop(); 2024 if (G1StringDedup::is_enabled()) { 2025 G1StringDedup::stop(); 2026 } 2027 } 2028 2029 void G1CollectedHeap::clear_humongous_is_live_table() { 2030 guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true"); 2031 _humongous_is_live.clear(); 2032 } 2033 2034 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2035 return HeapRegion::max_region_size(); 2036 } 2037 2038 void G1CollectedHeap::ref_processing_init() { 2039 // Reference processing in G1 currently works as follows: 2040 // 2041 // * There are two reference processor instances. One is 2042 // used to record and process discovered references 2043 // during concurrent marking; the other is used to 2044 // record and process references during STW pauses 2045 // (both full and incremental). 2046 // * Both ref processors need to 'span' the entire heap as 2047 // the regions in the collection set may be dotted around. 2048 // 2049 // * For the concurrent marking ref processor: 2050 // * Reference discovery is enabled at initial marking. 2051 // * Reference discovery is disabled and the discovered 2052 // references processed etc during remarking. 2053 // * Reference discovery is MT (see below). 2054 // * Reference discovery requires a barrier (see below). 2055 // * Reference processing may or may not be MT 2056 // (depending on the value of ParallelRefProcEnabled 2057 // and ParallelGCThreads). 2058 // * A full GC disables reference discovery by the CM 2059 // ref processor and abandons any entries on it's 2060 // discovered lists. 2061 // 2062 // * For the STW processor: 2063 // * Non MT discovery is enabled at the start of a full GC. 2064 // * Processing and enqueueing during a full GC is non-MT. 2065 // * During a full GC, references are processed after marking. 2066 // 2067 // * Discovery (may or may not be MT) is enabled at the start 2068 // of an incremental evacuation pause. 2069 // * References are processed near the end of a STW evacuation pause. 2070 // * For both types of GC: 2071 // * Discovery is atomic - i.e. not concurrent. 2072 // * Reference discovery will not need a barrier. 2073 2074 SharedHeap::ref_processing_init(); 2075 MemRegion mr = reserved_region(); 2076 2077 // Concurrent Mark ref processor 2078 _ref_processor_cm = 2079 new ReferenceProcessor(mr, // span 2080 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2081 // mt processing 2082 (int) ParallelGCThreads, 2083 // degree of mt processing 2084 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2085 // mt discovery 2086 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2087 // degree of mt discovery 2088 false, 2089 // Reference discovery is not atomic 2090 &_is_alive_closure_cm); 2091 // is alive closure 2092 // (for efficiency/performance) 2093 2094 // STW ref processor 2095 _ref_processor_stw = 2096 new ReferenceProcessor(mr, // span 2097 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2098 // mt processing 2099 MAX2((int)ParallelGCThreads, 1), 2100 // degree of mt processing 2101 (ParallelGCThreads > 1), 2102 // mt discovery 2103 MAX2((int)ParallelGCThreads, 1), 2104 // degree of mt discovery 2105 true, 2106 // Reference discovery is atomic 2107 &_is_alive_closure_stw); 2108 // is alive closure 2109 // (for efficiency/performance) 2110 } 2111 2112 size_t G1CollectedHeap::capacity() const { 2113 return _hrm.length() * HeapRegion::GrainBytes; 2114 } 2115 2116 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2117 assert(!hr->is_continues_humongous(), "pre-condition"); 2118 hr->reset_gc_time_stamp(); 2119 if (hr->is_starts_humongous()) { 2120 uint first_index = hr->hrm_index() + 1; 2121 uint last_index = hr->last_hc_index(); 2122 for (uint i = first_index; i < last_index; i += 1) { 2123 HeapRegion* chr = region_at(i); 2124 assert(chr->is_continues_humongous(), "sanity"); 2125 chr->reset_gc_time_stamp(); 2126 } 2127 } 2128 } 2129 2130 #ifndef PRODUCT 2131 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2132 private: 2133 unsigned _gc_time_stamp; 2134 bool _failures; 2135 2136 public: 2137 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2138 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2139 2140 virtual bool doHeapRegion(HeapRegion* hr) { 2141 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2142 if (_gc_time_stamp != region_gc_time_stamp) { 2143 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2144 "expected %d", HR_FORMAT_PARAMS(hr), 2145 region_gc_time_stamp, _gc_time_stamp); 2146 _failures = true; 2147 } 2148 return false; 2149 } 2150 2151 bool failures() { return _failures; } 2152 }; 2153 2154 void G1CollectedHeap::check_gc_time_stamps() { 2155 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2156 heap_region_iterate(&cl); 2157 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2158 } 2159 #endif // PRODUCT 2160 2161 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2162 DirtyCardQueue* into_cset_dcq, 2163 bool concurrent, 2164 uint worker_i) { 2165 // Clean cards in the hot card cache 2166 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2167 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2168 2169 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2170 size_t n_completed_buffers = 0; 2171 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2172 n_completed_buffers++; 2173 } 2174 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 2175 dcqs.clear_n_completed_buffers(); 2176 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2177 } 2178 2179 2180 // Computes the sum of the storage used by the various regions. 2181 size_t G1CollectedHeap::used() const { 2182 return _allocator->used(); 2183 } 2184 2185 size_t G1CollectedHeap::used_unlocked() const { 2186 return _allocator->used_unlocked(); 2187 } 2188 2189 class SumUsedClosure: public HeapRegionClosure { 2190 size_t _used; 2191 public: 2192 SumUsedClosure() : _used(0) {} 2193 bool doHeapRegion(HeapRegion* r) { 2194 if (!r->is_continues_humongous()) { 2195 _used += r->used(); 2196 } 2197 return false; 2198 } 2199 size_t result() { return _used; } 2200 }; 2201 2202 size_t G1CollectedHeap::recalculate_used() const { 2203 double recalculate_used_start = os::elapsedTime(); 2204 2205 SumUsedClosure blk; 2206 heap_region_iterate(&blk); 2207 2208 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2209 return blk.result(); 2210 } 2211 2212 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2213 switch (cause) { 2214 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2215 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2216 case GCCause::_g1_humongous_allocation: return true; 2217 case GCCause::_update_allocation_context_stats_inc: return true; 2218 case GCCause::_wb_conc_mark: return true; 2219 default: return false; 2220 } 2221 } 2222 2223 #ifndef PRODUCT 2224 void G1CollectedHeap::allocate_dummy_regions() { 2225 // Let's fill up most of the region 2226 size_t word_size = HeapRegion::GrainWords - 1024; 2227 // And as a result the region we'll allocate will be humongous. 2228 guarantee(is_humongous(word_size), "sanity"); 2229 2230 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2231 // Let's use the existing mechanism for the allocation 2232 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2233 AllocationContext::system()); 2234 if (dummy_obj != NULL) { 2235 MemRegion mr(dummy_obj, word_size); 2236 CollectedHeap::fill_with_object(mr); 2237 } else { 2238 // If we can't allocate once, we probably cannot allocate 2239 // again. Let's get out of the loop. 2240 break; 2241 } 2242 } 2243 } 2244 #endif // !PRODUCT 2245 2246 void G1CollectedHeap::increment_old_marking_cycles_started() { 2247 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2248 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2249 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2250 _old_marking_cycles_started, _old_marking_cycles_completed)); 2251 2252 _old_marking_cycles_started++; 2253 } 2254 2255 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2256 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2257 2258 // We assume that if concurrent == true, then the caller is a 2259 // concurrent thread that was joined the Suspendible Thread 2260 // Set. If there's ever a cheap way to check this, we should add an 2261 // assert here. 2262 2263 // Given that this method is called at the end of a Full GC or of a 2264 // concurrent cycle, and those can be nested (i.e., a Full GC can 2265 // interrupt a concurrent cycle), the number of full collections 2266 // completed should be either one (in the case where there was no 2267 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2268 // behind the number of full collections started. 2269 2270 // This is the case for the inner caller, i.e. a Full GC. 2271 assert(concurrent || 2272 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2273 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2274 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2275 "is inconsistent with _old_marking_cycles_completed = %u", 2276 _old_marking_cycles_started, _old_marking_cycles_completed)); 2277 2278 // This is the case for the outer caller, i.e. the concurrent cycle. 2279 assert(!concurrent || 2280 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2281 err_msg("for outer caller (concurrent cycle): " 2282 "_old_marking_cycles_started = %u " 2283 "is inconsistent with _old_marking_cycles_completed = %u", 2284 _old_marking_cycles_started, _old_marking_cycles_completed)); 2285 2286 _old_marking_cycles_completed += 1; 2287 2288 // We need to clear the "in_progress" flag in the CM thread before 2289 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2290 // is set) so that if a waiter requests another System.gc() it doesn't 2291 // incorrectly see that a marking cycle is still in progress. 2292 if (concurrent) { 2293 _cmThread->clear_in_progress(); 2294 } 2295 2296 // This notify_all() will ensure that a thread that called 2297 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2298 // and it's waiting for a full GC to finish will be woken up. It is 2299 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2300 FullGCCount_lock->notify_all(); 2301 } 2302 2303 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2304 _concurrent_cycle_started = true; 2305 _gc_timer_cm->register_gc_start(start_time); 2306 2307 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2308 trace_heap_before_gc(_gc_tracer_cm); 2309 } 2310 2311 void G1CollectedHeap::register_concurrent_cycle_end() { 2312 if (_concurrent_cycle_started) { 2313 if (_cm->has_aborted()) { 2314 _gc_tracer_cm->report_concurrent_mode_failure(); 2315 } 2316 2317 _gc_timer_cm->register_gc_end(); 2318 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2319 2320 // Clear state variables to prepare for the next concurrent cycle. 2321 _concurrent_cycle_started = false; 2322 _heap_summary_sent = false; 2323 } 2324 } 2325 2326 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2327 if (_concurrent_cycle_started) { 2328 // This function can be called when: 2329 // the cleanup pause is run 2330 // the concurrent cycle is aborted before the cleanup pause. 2331 // the concurrent cycle is aborted after the cleanup pause, 2332 // but before the concurrent cycle end has been registered. 2333 // Make sure that we only send the heap information once. 2334 if (!_heap_summary_sent) { 2335 trace_heap_after_gc(_gc_tracer_cm); 2336 _heap_summary_sent = true; 2337 } 2338 } 2339 } 2340 2341 G1YCType G1CollectedHeap::yc_type() { 2342 bool is_young = g1_policy()->gcs_are_young(); 2343 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2344 bool is_during_mark = mark_in_progress(); 2345 2346 if (is_initial_mark) { 2347 return InitialMark; 2348 } else if (is_during_mark) { 2349 return DuringMark; 2350 } else if (is_young) { 2351 return Normal; 2352 } else { 2353 return Mixed; 2354 } 2355 } 2356 2357 void G1CollectedHeap::collect(GCCause::Cause cause) { 2358 assert_heap_not_locked(); 2359 2360 uint gc_count_before; 2361 uint old_marking_count_before; 2362 uint full_gc_count_before; 2363 bool retry_gc; 2364 2365 do { 2366 retry_gc = false; 2367 2368 { 2369 MutexLocker ml(Heap_lock); 2370 2371 // Read the GC count while holding the Heap_lock 2372 gc_count_before = total_collections(); 2373 full_gc_count_before = total_full_collections(); 2374 old_marking_count_before = _old_marking_cycles_started; 2375 } 2376 2377 if (should_do_concurrent_full_gc(cause)) { 2378 // Schedule an initial-mark evacuation pause that will start a 2379 // concurrent cycle. We're setting word_size to 0 which means that 2380 // we are not requesting a post-GC allocation. 2381 VM_G1IncCollectionPause op(gc_count_before, 2382 0, /* word_size */ 2383 true, /* should_initiate_conc_mark */ 2384 g1_policy()->max_pause_time_ms(), 2385 cause); 2386 op.set_allocation_context(AllocationContext::current()); 2387 2388 VMThread::execute(&op); 2389 if (!op.pause_succeeded()) { 2390 if (old_marking_count_before == _old_marking_cycles_started) { 2391 retry_gc = op.should_retry_gc(); 2392 } else { 2393 // A Full GC happened while we were trying to schedule the 2394 // initial-mark GC. No point in starting a new cycle given 2395 // that the whole heap was collected anyway. 2396 } 2397 2398 if (retry_gc) { 2399 if (GC_locker::is_active_and_needs_gc()) { 2400 GC_locker::stall_until_clear(); 2401 } 2402 } 2403 } 2404 } else { 2405 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2406 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2407 2408 // Schedule a standard evacuation pause. We're setting word_size 2409 // to 0 which means that we are not requesting a post-GC allocation. 2410 VM_G1IncCollectionPause op(gc_count_before, 2411 0, /* word_size */ 2412 false, /* should_initiate_conc_mark */ 2413 g1_policy()->max_pause_time_ms(), 2414 cause); 2415 VMThread::execute(&op); 2416 } else { 2417 // Schedule a Full GC. 2418 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2419 VMThread::execute(&op); 2420 } 2421 } 2422 } while (retry_gc); 2423 } 2424 2425 bool G1CollectedHeap::is_in(const void* p) const { 2426 if (_hrm.reserved().contains(p)) { 2427 // Given that we know that p is in the reserved space, 2428 // heap_region_containing_raw() should successfully 2429 // return the containing region. 2430 HeapRegion* hr = heap_region_containing_raw(p); 2431 return hr->is_in(p); 2432 } else { 2433 return false; 2434 } 2435 } 2436 2437 #ifdef ASSERT 2438 bool G1CollectedHeap::is_in_exact(const void* p) const { 2439 bool contains = reserved_region().contains(p); 2440 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2441 if (contains && available) { 2442 return true; 2443 } else { 2444 return false; 2445 } 2446 } 2447 #endif 2448 2449 // Iteration functions. 2450 2451 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2452 2453 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2454 ExtendedOopClosure* _cl; 2455 public: 2456 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2457 bool doHeapRegion(HeapRegion* r) { 2458 if (!r->is_continues_humongous()) { 2459 r->oop_iterate(_cl); 2460 } 2461 return false; 2462 } 2463 }; 2464 2465 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 2466 IterateOopClosureRegionClosure blk(cl); 2467 heap_region_iterate(&blk); 2468 } 2469 2470 // Iterates an ObjectClosure over all objects within a HeapRegion. 2471 2472 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2473 ObjectClosure* _cl; 2474 public: 2475 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2476 bool doHeapRegion(HeapRegion* r) { 2477 if (!r->is_continues_humongous()) { 2478 r->object_iterate(_cl); 2479 } 2480 return false; 2481 } 2482 }; 2483 2484 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2485 IterateObjectClosureRegionClosure blk(cl); 2486 heap_region_iterate(&blk); 2487 } 2488 2489 // Calls a SpaceClosure on a HeapRegion. 2490 2491 class SpaceClosureRegionClosure: public HeapRegionClosure { 2492 SpaceClosure* _cl; 2493 public: 2494 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} 2495 bool doHeapRegion(HeapRegion* r) { 2496 _cl->do_space(r); 2497 return false; 2498 } 2499 }; 2500 2501 void G1CollectedHeap::space_iterate(SpaceClosure* cl) { 2502 SpaceClosureRegionClosure blk(cl); 2503 heap_region_iterate(&blk); 2504 } 2505 2506 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2507 _hrm.iterate(cl); 2508 } 2509 2510 void 2511 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, 2512 uint worker_id, 2513 HeapRegionClaimer *hrclaimer, 2514 bool concurrent) const { 2515 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); 2516 } 2517 2518 // Clear the cached CSet starting regions and (more importantly) 2519 // the time stamps. Called when we reset the GC time stamp. 2520 void G1CollectedHeap::clear_cset_start_regions() { 2521 assert(_worker_cset_start_region != NULL, "sanity"); 2522 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2523 2524 int n_queues = MAX2((int)ParallelGCThreads, 1); 2525 for (int i = 0; i < n_queues; i++) { 2526 _worker_cset_start_region[i] = NULL; 2527 _worker_cset_start_region_time_stamp[i] = 0; 2528 } 2529 } 2530 2531 // Given the id of a worker, obtain or calculate a suitable 2532 // starting region for iterating over the current collection set. 2533 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2534 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2535 2536 HeapRegion* result = NULL; 2537 unsigned gc_time_stamp = get_gc_time_stamp(); 2538 2539 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2540 // Cached starting region for current worker was set 2541 // during the current pause - so it's valid. 2542 // Note: the cached starting heap region may be NULL 2543 // (when the collection set is empty). 2544 result = _worker_cset_start_region[worker_i]; 2545 assert(result == NULL || result->in_collection_set(), "sanity"); 2546 return result; 2547 } 2548 2549 // The cached entry was not valid so let's calculate 2550 // a suitable starting heap region for this worker. 2551 2552 // We want the parallel threads to start their collection 2553 // set iteration at different collection set regions to 2554 // avoid contention. 2555 // If we have: 2556 // n collection set regions 2557 // p threads 2558 // Then thread t will start at region floor ((t * n) / p) 2559 2560 result = g1_policy()->collection_set(); 2561 uint cs_size = g1_policy()->cset_region_length(); 2562 uint active_workers = workers()->active_workers(); 2563 assert(UseDynamicNumberOfGCThreads || 2564 active_workers == workers()->total_workers(), 2565 "Unless dynamic should use total workers"); 2566 2567 uint end_ind = (cs_size * worker_i) / active_workers; 2568 uint start_ind = 0; 2569 2570 if (worker_i > 0 && 2571 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2572 // Previous workers starting region is valid 2573 // so let's iterate from there 2574 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2575 result = _worker_cset_start_region[worker_i - 1]; 2576 } 2577 2578 for (uint i = start_ind; i < end_ind; i++) { 2579 result = result->next_in_collection_set(); 2580 } 2581 2582 // Note: the calculated starting heap region may be NULL 2583 // (when the collection set is empty). 2584 assert(result == NULL || result->in_collection_set(), "sanity"); 2585 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2586 "should be updated only once per pause"); 2587 _worker_cset_start_region[worker_i] = result; 2588 OrderAccess::storestore(); 2589 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2590 return result; 2591 } 2592 2593 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2594 HeapRegion* r = g1_policy()->collection_set(); 2595 while (r != NULL) { 2596 HeapRegion* next = r->next_in_collection_set(); 2597 if (cl->doHeapRegion(r)) { 2598 cl->incomplete(); 2599 return; 2600 } 2601 r = next; 2602 } 2603 } 2604 2605 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2606 HeapRegionClosure *cl) { 2607 if (r == NULL) { 2608 // The CSet is empty so there's nothing to do. 2609 return; 2610 } 2611 2612 assert(r->in_collection_set(), 2613 "Start region must be a member of the collection set."); 2614 HeapRegion* cur = r; 2615 while (cur != NULL) { 2616 HeapRegion* next = cur->next_in_collection_set(); 2617 if (cl->doHeapRegion(cur) && false) { 2618 cl->incomplete(); 2619 return; 2620 } 2621 cur = next; 2622 } 2623 cur = g1_policy()->collection_set(); 2624 while (cur != r) { 2625 HeapRegion* next = cur->next_in_collection_set(); 2626 if (cl->doHeapRegion(cur) && false) { 2627 cl->incomplete(); 2628 return; 2629 } 2630 cur = next; 2631 } 2632 } 2633 2634 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2635 HeapRegion* result = _hrm.next_region_in_heap(from); 2636 while (result != NULL && result->is_humongous()) { 2637 result = _hrm.next_region_in_heap(result); 2638 } 2639 return result; 2640 } 2641 2642 Space* G1CollectedHeap::space_containing(const void* addr) const { 2643 return heap_region_containing(addr); 2644 } 2645 2646 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2647 Space* sp = space_containing(addr); 2648 return sp->block_start(addr); 2649 } 2650 2651 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2652 Space* sp = space_containing(addr); 2653 return sp->block_size(addr); 2654 } 2655 2656 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2657 Space* sp = space_containing(addr); 2658 return sp->block_is_obj(addr); 2659 } 2660 2661 bool G1CollectedHeap::supports_tlab_allocation() const { 2662 return true; 2663 } 2664 2665 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2666 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2667 } 2668 2669 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2670 return young_list()->eden_used_bytes(); 2671 } 2672 2673 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2674 // must be smaller than the humongous object limit. 2675 size_t G1CollectedHeap::max_tlab_size() const { 2676 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 2677 } 2678 2679 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2680 // Return the remaining space in the cur alloc region, but not less than 2681 // the min TLAB size. 2682 2683 // Also, this value can be at most the humongous object threshold, 2684 // since we can't allow tlabs to grow big enough to accommodate 2685 // humongous objects. 2686 2687 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get(); 2688 size_t max_tlab = max_tlab_size() * wordSize; 2689 if (hr == NULL) { 2690 return max_tlab; 2691 } else { 2692 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 2693 } 2694 } 2695 2696 size_t G1CollectedHeap::max_capacity() const { 2697 return _hrm.reserved().byte_size(); 2698 } 2699 2700 jlong G1CollectedHeap::millis_since_last_gc() { 2701 // assert(false, "NYI"); 2702 return 0; 2703 } 2704 2705 void G1CollectedHeap::prepare_for_verify() { 2706 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2707 ensure_parsability(false); 2708 } 2709 g1_rem_set()->prepare_for_verify(); 2710 } 2711 2712 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 2713 VerifyOption vo) { 2714 switch (vo) { 2715 case VerifyOption_G1UsePrevMarking: 2716 return hr->obj_allocated_since_prev_marking(obj); 2717 case VerifyOption_G1UseNextMarking: 2718 return hr->obj_allocated_since_next_marking(obj); 2719 case VerifyOption_G1UseMarkWord: 2720 return false; 2721 default: 2722 ShouldNotReachHere(); 2723 } 2724 return false; // keep some compilers happy 2725 } 2726 2727 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 2728 switch (vo) { 2729 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 2730 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 2731 case VerifyOption_G1UseMarkWord: return NULL; 2732 default: ShouldNotReachHere(); 2733 } 2734 return NULL; // keep some compilers happy 2735 } 2736 2737 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 2738 switch (vo) { 2739 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 2740 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 2741 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 2742 default: ShouldNotReachHere(); 2743 } 2744 return false; // keep some compilers happy 2745 } 2746 2747 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 2748 switch (vo) { 2749 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 2750 case VerifyOption_G1UseNextMarking: return "NTAMS"; 2751 case VerifyOption_G1UseMarkWord: return "NONE"; 2752 default: ShouldNotReachHere(); 2753 } 2754 return NULL; // keep some compilers happy 2755 } 2756 2757 class VerifyRootsClosure: public OopClosure { 2758 private: 2759 G1CollectedHeap* _g1h; 2760 VerifyOption _vo; 2761 bool _failures; 2762 public: 2763 // _vo == UsePrevMarking -> use "prev" marking information, 2764 // _vo == UseNextMarking -> use "next" marking information, 2765 // _vo == UseMarkWord -> use mark word from object header. 2766 VerifyRootsClosure(VerifyOption vo) : 2767 _g1h(G1CollectedHeap::heap()), 2768 _vo(vo), 2769 _failures(false) { } 2770 2771 bool failures() { return _failures; } 2772 2773 template <class T> void do_oop_nv(T* p) { 2774 T heap_oop = oopDesc::load_heap_oop(p); 2775 if (!oopDesc::is_null(heap_oop)) { 2776 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2777 if (_g1h->is_obj_dead_cond(obj, _vo)) { 2778 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 2779 "points to dead obj "PTR_FORMAT, p, (void*) obj); 2780 if (_vo == VerifyOption_G1UseMarkWord) { 2781 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 2782 } 2783 obj->print_on(gclog_or_tty); 2784 _failures = true; 2785 } 2786 } 2787 } 2788 2789 void do_oop(oop* p) { do_oop_nv(p); } 2790 void do_oop(narrowOop* p) { do_oop_nv(p); } 2791 }; 2792 2793 class G1VerifyCodeRootOopClosure: public OopClosure { 2794 G1CollectedHeap* _g1h; 2795 OopClosure* _root_cl; 2796 nmethod* _nm; 2797 VerifyOption _vo; 2798 bool _failures; 2799 2800 template <class T> void do_oop_work(T* p) { 2801 // First verify that this root is live 2802 _root_cl->do_oop(p); 2803 2804 if (!G1VerifyHeapRegionCodeRoots) { 2805 // We're not verifying the code roots attached to heap region. 2806 return; 2807 } 2808 2809 // Don't check the code roots during marking verification in a full GC 2810 if (_vo == VerifyOption_G1UseMarkWord) { 2811 return; 2812 } 2813 2814 // Now verify that the current nmethod (which contains p) is 2815 // in the code root list of the heap region containing the 2816 // object referenced by p. 2817 2818 T heap_oop = oopDesc::load_heap_oop(p); 2819 if (!oopDesc::is_null(heap_oop)) { 2820 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2821 2822 // Now fetch the region containing the object 2823 HeapRegion* hr = _g1h->heap_region_containing(obj); 2824 HeapRegionRemSet* hrrs = hr->rem_set(); 2825 // Verify that the strong code root list for this region 2826 // contains the nmethod 2827 if (!hrrs->strong_code_roots_list_contains(_nm)) { 2828 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " 2829 "from nmethod "PTR_FORMAT" not in strong " 2830 "code roots for region ["PTR_FORMAT","PTR_FORMAT")", 2831 p, _nm, hr->bottom(), hr->end()); 2832 _failures = true; 2833 } 2834 } 2835 } 2836 2837 public: 2838 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 2839 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 2840 2841 void do_oop(oop* p) { do_oop_work(p); } 2842 void do_oop(narrowOop* p) { do_oop_work(p); } 2843 2844 void set_nmethod(nmethod* nm) { _nm = nm; } 2845 bool failures() { return _failures; } 2846 }; 2847 2848 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 2849 G1VerifyCodeRootOopClosure* _oop_cl; 2850 2851 public: 2852 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 2853 _oop_cl(oop_cl) {} 2854 2855 void do_code_blob(CodeBlob* cb) { 2856 nmethod* nm = cb->as_nmethod_or_null(); 2857 if (nm != NULL) { 2858 _oop_cl->set_nmethod(nm); 2859 nm->oops_do(_oop_cl); 2860 } 2861 } 2862 }; 2863 2864 class YoungRefCounterClosure : public OopClosure { 2865 G1CollectedHeap* _g1h; 2866 int _count; 2867 public: 2868 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 2869 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 2870 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 2871 2872 int count() { return _count; } 2873 void reset_count() { _count = 0; }; 2874 }; 2875 2876 class VerifyKlassClosure: public KlassClosure { 2877 YoungRefCounterClosure _young_ref_counter_closure; 2878 OopClosure *_oop_closure; 2879 public: 2880 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 2881 void do_klass(Klass* k) { 2882 k->oops_do(_oop_closure); 2883 2884 _young_ref_counter_closure.reset_count(); 2885 k->oops_do(&_young_ref_counter_closure); 2886 if (_young_ref_counter_closure.count() > 0) { 2887 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k)); 2888 } 2889 } 2890 }; 2891 2892 class VerifyLivenessOopClosure: public OopClosure { 2893 G1CollectedHeap* _g1h; 2894 VerifyOption _vo; 2895 public: 2896 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 2897 _g1h(g1h), _vo(vo) 2898 { } 2899 void do_oop(narrowOop *p) { do_oop_work(p); } 2900 void do_oop( oop *p) { do_oop_work(p); } 2901 2902 template <class T> void do_oop_work(T *p) { 2903 oop obj = oopDesc::load_decode_heap_oop(p); 2904 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 2905 "Dead object referenced by a not dead object"); 2906 } 2907 }; 2908 2909 class VerifyObjsInRegionClosure: public ObjectClosure { 2910 private: 2911 G1CollectedHeap* _g1h; 2912 size_t _live_bytes; 2913 HeapRegion *_hr; 2914 VerifyOption _vo; 2915 public: 2916 // _vo == UsePrevMarking -> use "prev" marking information, 2917 // _vo == UseNextMarking -> use "next" marking information, 2918 // _vo == UseMarkWord -> use mark word from object header. 2919 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 2920 : _live_bytes(0), _hr(hr), _vo(vo) { 2921 _g1h = G1CollectedHeap::heap(); 2922 } 2923 void do_object(oop o) { 2924 VerifyLivenessOopClosure isLive(_g1h, _vo); 2925 assert(o != NULL, "Huh?"); 2926 if (!_g1h->is_obj_dead_cond(o, _vo)) { 2927 // If the object is alive according to the mark word, 2928 // then verify that the marking information agrees. 2929 // Note we can't verify the contra-positive of the 2930 // above: if the object is dead (according to the mark 2931 // word), it may not be marked, or may have been marked 2932 // but has since became dead, or may have been allocated 2933 // since the last marking. 2934 if (_vo == VerifyOption_G1UseMarkWord) { 2935 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 2936 } 2937 2938 o->oop_iterate_no_header(&isLive); 2939 if (!_hr->obj_allocated_since_prev_marking(o)) { 2940 size_t obj_size = o->size(); // Make sure we don't overflow 2941 _live_bytes += (obj_size * HeapWordSize); 2942 } 2943 } 2944 } 2945 size_t live_bytes() { return _live_bytes; } 2946 }; 2947 2948 class PrintObjsInRegionClosure : public ObjectClosure { 2949 HeapRegion *_hr; 2950 G1CollectedHeap *_g1; 2951 public: 2952 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 2953 _g1 = G1CollectedHeap::heap(); 2954 }; 2955 2956 void do_object(oop o) { 2957 if (o != NULL) { 2958 HeapWord *start = (HeapWord *) o; 2959 size_t word_sz = o->size(); 2960 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 2961 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 2962 (void*) o, word_sz, 2963 _g1->isMarkedPrev(o), 2964 _g1->isMarkedNext(o), 2965 _hr->obj_allocated_since_prev_marking(o)); 2966 HeapWord *end = start + word_sz; 2967 HeapWord *cur; 2968 int *val; 2969 for (cur = start; cur < end; cur++) { 2970 val = (int *) cur; 2971 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val); 2972 } 2973 } 2974 } 2975 }; 2976 2977 class VerifyRegionClosure: public HeapRegionClosure { 2978 private: 2979 bool _par; 2980 VerifyOption _vo; 2981 bool _failures; 2982 public: 2983 // _vo == UsePrevMarking -> use "prev" marking information, 2984 // _vo == UseNextMarking -> use "next" marking information, 2985 // _vo == UseMarkWord -> use mark word from object header. 2986 VerifyRegionClosure(bool par, VerifyOption vo) 2987 : _par(par), 2988 _vo(vo), 2989 _failures(false) {} 2990 2991 bool failures() { 2992 return _failures; 2993 } 2994 2995 bool doHeapRegion(HeapRegion* r) { 2996 if (!r->is_continues_humongous()) { 2997 bool failures = false; 2998 r->verify(_vo, &failures); 2999 if (failures) { 3000 _failures = true; 3001 } else { 3002 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3003 r->object_iterate(¬_dead_yet_cl); 3004 if (_vo != VerifyOption_G1UseNextMarking) { 3005 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3006 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 3007 "max_live_bytes "SIZE_FORMAT" " 3008 "< calculated "SIZE_FORMAT, 3009 r->bottom(), r->end(), 3010 r->max_live_bytes(), 3011 not_dead_yet_cl.live_bytes()); 3012 _failures = true; 3013 } 3014 } else { 3015 // When vo == UseNextMarking we cannot currently do a sanity 3016 // check on the live bytes as the calculation has not been 3017 // finalized yet. 3018 } 3019 } 3020 } 3021 return false; // stop the region iteration if we hit a failure 3022 } 3023 }; 3024 3025 // This is the task used for parallel verification of the heap regions 3026 3027 class G1ParVerifyTask: public AbstractGangTask { 3028 private: 3029 G1CollectedHeap* _g1h; 3030 VerifyOption _vo; 3031 bool _failures; 3032 HeapRegionClaimer _hrclaimer; 3033 3034 public: 3035 // _vo == UsePrevMarking -> use "prev" marking information, 3036 // _vo == UseNextMarking -> use "next" marking information, 3037 // _vo == UseMarkWord -> use mark word from object header. 3038 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3039 AbstractGangTask("Parallel verify task"), 3040 _g1h(g1h), 3041 _vo(vo), 3042 _failures(false), 3043 _hrclaimer(g1h->workers()->active_workers()) {} 3044 3045 bool failures() { 3046 return _failures; 3047 } 3048 3049 void work(uint worker_id) { 3050 HandleMark hm; 3051 VerifyRegionClosure blk(true, _vo); 3052 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer); 3053 if (blk.failures()) { 3054 _failures = true; 3055 } 3056 } 3057 }; 3058 3059 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3060 if (SafepointSynchronize::is_at_safepoint()) { 3061 assert(Thread::current()->is_VM_thread(), 3062 "Expected to be executed serially by the VM thread at this point"); 3063 3064 if (!silent) { gclog_or_tty->print("Roots "); } 3065 VerifyRootsClosure rootsCl(vo); 3066 VerifyKlassClosure klassCl(this, &rootsCl); 3067 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3068 3069 // We apply the relevant closures to all the oops in the 3070 // system dictionary, class loader data graph, the string table 3071 // and the nmethods in the code cache. 3072 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3073 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3074 3075 { 3076 G1RootProcessor root_processor(this); 3077 root_processor.process_all_roots(&rootsCl, 3078 &cldCl, 3079 &blobsCl); 3080 } 3081 3082 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3083 3084 if (vo != VerifyOption_G1UseMarkWord) { 3085 // If we're verifying during a full GC then the region sets 3086 // will have been torn down at the start of the GC. Therefore 3087 // verifying the region sets will fail. So we only verify 3088 // the region sets when not in a full GC. 3089 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3090 verify_region_sets(); 3091 } 3092 3093 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3094 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3095 3096 G1ParVerifyTask task(this, vo); 3097 assert(UseDynamicNumberOfGCThreads || 3098 workers()->active_workers() == workers()->total_workers(), 3099 "If not dynamic should be using all the workers"); 3100 int n_workers = workers()->active_workers(); 3101 set_par_threads(n_workers); 3102 workers()->run_task(&task); 3103 set_par_threads(0); 3104 if (task.failures()) { 3105 failures = true; 3106 } 3107 3108 } else { 3109 VerifyRegionClosure blk(false, vo); 3110 heap_region_iterate(&blk); 3111 if (blk.failures()) { 3112 failures = true; 3113 } 3114 } 3115 3116 if (G1StringDedup::is_enabled()) { 3117 if (!silent) gclog_or_tty->print("StrDedup "); 3118 G1StringDedup::verify(); 3119 } 3120 3121 if (failures) { 3122 gclog_or_tty->print_cr("Heap:"); 3123 // It helps to have the per-region information in the output to 3124 // help us track down what went wrong. This is why we call 3125 // print_extended_on() instead of print_on(). 3126 print_extended_on(gclog_or_tty); 3127 gclog_or_tty->cr(); 3128 #ifndef PRODUCT 3129 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 3130 concurrent_mark()->print_reachable("at-verification-failure", 3131 vo, false /* all */); 3132 } 3133 #endif 3134 gclog_or_tty->flush(); 3135 } 3136 guarantee(!failures, "there should not have been any failures"); 3137 } else { 3138 if (!silent) { 3139 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3140 if (G1StringDedup::is_enabled()) { 3141 gclog_or_tty->print(", StrDedup"); 3142 } 3143 gclog_or_tty->print(") "); 3144 } 3145 } 3146 } 3147 3148 void G1CollectedHeap::verify(bool silent) { 3149 verify(silent, VerifyOption_G1UsePrevMarking); 3150 } 3151 3152 double G1CollectedHeap::verify(bool guard, const char* msg) { 3153 double verify_time_ms = 0.0; 3154 3155 if (guard && total_collections() >= VerifyGCStartAt) { 3156 double verify_start = os::elapsedTime(); 3157 HandleMark hm; // Discard invalid handles created during verification 3158 prepare_for_verify(); 3159 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3160 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3161 } 3162 3163 return verify_time_ms; 3164 } 3165 3166 void G1CollectedHeap::verify_before_gc() { 3167 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3168 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3169 } 3170 3171 void G1CollectedHeap::verify_after_gc() { 3172 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3173 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3174 } 3175 3176 class PrintRegionClosure: public HeapRegionClosure { 3177 outputStream* _st; 3178 public: 3179 PrintRegionClosure(outputStream* st) : _st(st) {} 3180 bool doHeapRegion(HeapRegion* r) { 3181 r->print_on(_st); 3182 return false; 3183 } 3184 }; 3185 3186 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3187 const HeapRegion* hr, 3188 const VerifyOption vo) const { 3189 switch (vo) { 3190 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3191 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3192 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3193 default: ShouldNotReachHere(); 3194 } 3195 return false; // keep some compilers happy 3196 } 3197 3198 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3199 const VerifyOption vo) const { 3200 switch (vo) { 3201 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3202 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3203 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3204 default: ShouldNotReachHere(); 3205 } 3206 return false; // keep some compilers happy 3207 } 3208 3209 void G1CollectedHeap::print_on(outputStream* st) const { 3210 st->print(" %-20s", "garbage-first heap"); 3211 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3212 capacity()/K, used_unlocked()/K); 3213 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3214 _hrm.reserved().start(), 3215 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords, 3216 _hrm.reserved().end()); 3217 st->cr(); 3218 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3219 uint young_regions = _young_list->length(); 3220 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3221 (size_t) young_regions * HeapRegion::GrainBytes / K); 3222 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3223 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3224 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3225 st->cr(); 3226 MetaspaceAux::print_on(st); 3227 } 3228 3229 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3230 print_on(st); 3231 3232 // Print the per-region information. 3233 st->cr(); 3234 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3235 "HS=humongous(starts), HC=humongous(continues), " 3236 "CS=collection set, F=free, TS=gc time stamp, " 3237 "PTAMS=previous top-at-mark-start, " 3238 "NTAMS=next top-at-mark-start)"); 3239 PrintRegionClosure blk(st); 3240 heap_region_iterate(&blk); 3241 } 3242 3243 void G1CollectedHeap::print_on_error(outputStream* st) const { 3244 this->CollectedHeap::print_on_error(st); 3245 3246 if (_cm != NULL) { 3247 st->cr(); 3248 _cm->print_on_error(st); 3249 } 3250 } 3251 3252 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3253 workers()->print_worker_threads_on(st); 3254 _cmThread->print_on(st); 3255 st->cr(); 3256 _cm->print_worker_threads_on(st); 3257 _cg1r->print_worker_threads_on(st); 3258 if (G1StringDedup::is_enabled()) { 3259 G1StringDedup::print_worker_threads_on(st); 3260 } 3261 } 3262 3263 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3264 workers()->threads_do(tc); 3265 tc->do_thread(_cmThread); 3266 _cg1r->threads_do(tc); 3267 if (G1StringDedup::is_enabled()) { 3268 G1StringDedup::threads_do(tc); 3269 } 3270 } 3271 3272 void G1CollectedHeap::print_tracing_info() const { 3273 // We'll overload this to mean "trace GC pause statistics." 3274 if (TraceYoungGenTime || TraceOldGenTime) { 3275 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3276 // to that. 3277 g1_policy()->print_tracing_info(); 3278 } 3279 if (G1SummarizeRSetStats) { 3280 g1_rem_set()->print_summary_info(); 3281 } 3282 if (G1SummarizeConcMark) { 3283 concurrent_mark()->print_summary_info(); 3284 } 3285 g1_policy()->print_yg_surv_rate_info(); 3286 } 3287 3288 #ifndef PRODUCT 3289 // Helpful for debugging RSet issues. 3290 3291 class PrintRSetsClosure : public HeapRegionClosure { 3292 private: 3293 const char* _msg; 3294 size_t _occupied_sum; 3295 3296 public: 3297 bool doHeapRegion(HeapRegion* r) { 3298 HeapRegionRemSet* hrrs = r->rem_set(); 3299 size_t occupied = hrrs->occupied(); 3300 _occupied_sum += occupied; 3301 3302 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3303 HR_FORMAT_PARAMS(r)); 3304 if (occupied == 0) { 3305 gclog_or_tty->print_cr(" RSet is empty"); 3306 } else { 3307 hrrs->print(); 3308 } 3309 gclog_or_tty->print_cr("----------"); 3310 return false; 3311 } 3312 3313 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3314 gclog_or_tty->cr(); 3315 gclog_or_tty->print_cr("========================================"); 3316 gclog_or_tty->print_cr("%s", msg); 3317 gclog_or_tty->cr(); 3318 } 3319 3320 ~PrintRSetsClosure() { 3321 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3322 gclog_or_tty->print_cr("========================================"); 3323 gclog_or_tty->cr(); 3324 } 3325 }; 3326 3327 void G1CollectedHeap::print_cset_rsets() { 3328 PrintRSetsClosure cl("Printing CSet RSets"); 3329 collection_set_iterate(&cl); 3330 } 3331 3332 void G1CollectedHeap::print_all_rsets() { 3333 PrintRSetsClosure cl("Printing All RSets");; 3334 heap_region_iterate(&cl); 3335 } 3336 #endif // PRODUCT 3337 3338 G1CollectedHeap* G1CollectedHeap::heap() { 3339 assert(_sh->kind() == CollectedHeap::G1CollectedHeap, 3340 "not a garbage-first 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 = workers()->active_workers(); 3716 double pause_start_sec = os::elapsedTime(); 3717 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress()); 3718 log_gc_header(); 3719 3720 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3721 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3722 3723 // If the secondary_free_list is not empty, append it to the 3724 // free_list. No need to wait for the cleanup operation to finish; 3725 // the region allocation code will check the secondary_free_list 3726 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3727 // set, skip this step so that the region allocation code has to 3728 // get entries from the secondary_free_list. 3729 if (!G1StressConcRegionFreeing) { 3730 append_secondary_free_list_if_not_empty_with_lock(); 3731 } 3732 3733 assert(check_young_list_well_formed(), "young list should be well formed"); 3734 3735 // Don't dynamically change the number of GC threads this early. A value of 3736 // 0 is used to indicate serial work. When parallel work is done, 3737 // it will be set. 3738 3739 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3740 IsGCActiveMark x; 3741 3742 gc_prologue(false); 3743 increment_total_collections(false /* full gc */); 3744 increment_gc_time_stamp(); 3745 3746 verify_before_gc(); 3747 3748 check_bitmaps("GC Start"); 3749 3750 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3751 3752 // Please see comment in g1CollectedHeap.hpp and 3753 // G1CollectedHeap::ref_processing_init() to see how 3754 // reference processing currently works in G1. 3755 3756 // Enable discovery in the STW reference processor 3757 ref_processor_stw()->enable_discovery(); 3758 3759 { 3760 // We want to temporarily turn off discovery by the 3761 // CM ref processor, if necessary, and turn it back on 3762 // on again later if we do. Using a scoped 3763 // NoRefDiscovery object will do this. 3764 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3765 3766 // Forget the current alloc region (we might even choose it to be part 3767 // of the collection set!). 3768 _allocator->release_mutator_alloc_region(); 3769 3770 // We should call this after we retire the mutator alloc 3771 // region(s) so that all the ALLOC / RETIRE events are generated 3772 // before the start GC event. 3773 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3774 3775 // This timing is only used by the ergonomics to handle our pause target. 3776 // It is unclear why this should not include the full pause. We will 3777 // investigate this in CR 7178365. 3778 // 3779 // Preserving the old comment here if that helps the investigation: 3780 // 3781 // The elapsed time induced by the start time below deliberately elides 3782 // the possible verification above. 3783 double sample_start_time_sec = os::elapsedTime(); 3784 3785 #if YOUNG_LIST_VERBOSE 3786 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 3787 _young_list->print(); 3788 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3789 #endif // YOUNG_LIST_VERBOSE 3790 3791 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3792 3793 double scan_wait_start = os::elapsedTime(); 3794 // We have to wait until the CM threads finish scanning the 3795 // root regions as it's the only way to ensure that all the 3796 // objects on them have been correctly scanned before we start 3797 // moving them during the GC. 3798 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3799 double wait_time_ms = 0.0; 3800 if (waited) { 3801 double scan_wait_end = os::elapsedTime(); 3802 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3803 } 3804 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3805 3806 #if YOUNG_LIST_VERBOSE 3807 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 3808 _young_list->print(); 3809 #endif // YOUNG_LIST_VERBOSE 3810 3811 if (g1_policy()->during_initial_mark_pause()) { 3812 concurrent_mark()->checkpointRootsInitialPre(); 3813 } 3814 3815 #if YOUNG_LIST_VERBOSE 3816 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 3817 _young_list->print(); 3818 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3819 #endif // YOUNG_LIST_VERBOSE 3820 3821 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 3822 3823 register_humongous_regions_with_cset(); 3824 3825 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3826 3827 _cm->note_start_of_gc(); 3828 // We should not verify the per-thread SATB buffers given that 3829 // we have not filtered them yet (we'll do so during the 3830 // GC). We also call this after finalize_cset() to 3831 // ensure that the CSet has been finalized. 3832 _cm->verify_no_cset_oops(true /* verify_stacks */, 3833 true /* verify_enqueued_buffers */, 3834 false /* verify_thread_buffers */, 3835 true /* verify_fingers */); 3836 3837 if (_hr_printer.is_active()) { 3838 HeapRegion* hr = g1_policy()->collection_set(); 3839 while (hr != NULL) { 3840 _hr_printer.cset(hr); 3841 hr = hr->next_in_collection_set(); 3842 } 3843 } 3844 3845 #ifdef ASSERT 3846 VerifyCSetClosure cl; 3847 collection_set_iterate(&cl); 3848 #endif // ASSERT 3849 3850 setup_surviving_young_words(); 3851 3852 // Initialize the GC alloc regions. 3853 _allocator->init_gc_alloc_regions(evacuation_info); 3854 3855 // Actually do the work... 3856 evacuate_collection_set(evacuation_info); 3857 3858 // We do this to mainly verify the per-thread SATB buffers 3859 // (which have been filtered by now) since we didn't verify 3860 // them earlier. No point in re-checking the stacks / enqueued 3861 // buffers given that the CSet has not changed since last time 3862 // we checked. 3863 _cm->verify_no_cset_oops(false /* verify_stacks */, 3864 false /* verify_enqueued_buffers */, 3865 true /* verify_thread_buffers */, 3866 true /* verify_fingers */); 3867 3868 free_collection_set(g1_policy()->collection_set(), evacuation_info); 3869 3870 eagerly_reclaim_humongous_regions(); 3871 3872 g1_policy()->clear_collection_set(); 3873 3874 cleanup_surviving_young_words(); 3875 3876 // Start a new incremental collection set for the next pause. 3877 g1_policy()->start_incremental_cset_building(); 3878 3879 clear_cset_fast_test(); 3880 3881 _young_list->reset_sampled_info(); 3882 3883 // Don't check the whole heap at this point as the 3884 // GC alloc regions from this pause have been tagged 3885 // as survivors and moved on to the survivor list. 3886 // Survivor regions will fail the !is_young() check. 3887 assert(check_young_list_empty(false /* check_heap */), 3888 "young list should be empty"); 3889 3890 #if YOUNG_LIST_VERBOSE 3891 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 3892 _young_list->print(); 3893 #endif // YOUNG_LIST_VERBOSE 3894 3895 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 3896 _young_list->first_survivor_region(), 3897 _young_list->last_survivor_region()); 3898 3899 _young_list->reset_auxilary_lists(); 3900 3901 if (evacuation_failed()) { 3902 _allocator->set_used(recalculate_used()); 3903 uint n_queues = MAX2((int)ParallelGCThreads, 1); 3904 for (uint i = 0; i < n_queues; i++) { 3905 if (_evacuation_failed_info_array[i].has_failed()) { 3906 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3907 } 3908 } 3909 } else { 3910 // The "used" of the the collection set have already been subtracted 3911 // when they were freed. Add in the bytes evacuated. 3912 _allocator->increase_used(g1_policy()->bytes_copied_during_gc()); 3913 } 3914 3915 if (g1_policy()->during_initial_mark_pause()) { 3916 // We have to do this before we notify the CM threads that 3917 // they can start working to make sure that all the 3918 // appropriate initialization is done on the CM object. 3919 concurrent_mark()->checkpointRootsInitialPost(); 3920 set_marking_started(); 3921 // Note that we don't actually trigger the CM thread at 3922 // this point. We do that later when we're sure that 3923 // the current thread has completed its logging output. 3924 } 3925 3926 allocate_dummy_regions(); 3927 3928 #if YOUNG_LIST_VERBOSE 3929 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 3930 _young_list->print(); 3931 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3932 #endif // YOUNG_LIST_VERBOSE 3933 3934 _allocator->init_mutator_alloc_region(); 3935 3936 { 3937 size_t expand_bytes = g1_policy()->expansion_amount(); 3938 if (expand_bytes > 0) { 3939 size_t bytes_before = capacity(); 3940 // No need for an ergo verbose message here, 3941 // expansion_amount() does this when it returns a value > 0. 3942 if (!expand(expand_bytes)) { 3943 // We failed to expand the heap. Cannot do anything about it. 3944 } 3945 } 3946 } 3947 3948 // We redo the verification but now wrt to the new CSet which 3949 // has just got initialized after the previous CSet was freed. 3950 _cm->verify_no_cset_oops(true /* verify_stacks */, 3951 true /* verify_enqueued_buffers */, 3952 true /* verify_thread_buffers */, 3953 true /* verify_fingers */); 3954 _cm->note_end_of_gc(); 3955 3956 // This timing is only used by the ergonomics to handle our pause target. 3957 // It is unclear why this should not include the full pause. We will 3958 // investigate this in CR 7178365. 3959 double sample_end_time_sec = os::elapsedTime(); 3960 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3961 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 3962 3963 MemoryService::track_memory_usage(); 3964 3965 // In prepare_for_verify() below we'll need to scan the deferred 3966 // update buffers to bring the RSets up-to-date if 3967 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 3968 // the update buffers we'll probably need to scan cards on the 3969 // regions we just allocated to (i.e., the GC alloc 3970 // regions). However, during the last GC we called 3971 // set_saved_mark() on all the GC alloc regions, so card 3972 // scanning might skip the [saved_mark_word()...top()] area of 3973 // those regions (i.e., the area we allocated objects into 3974 // during the last GC). But it shouldn't. Given that 3975 // saved_mark_word() is conditional on whether the GC time stamp 3976 // on the region is current or not, by incrementing the GC time 3977 // stamp here we invalidate all the GC time stamps on all the 3978 // regions and saved_mark_word() will simply return top() for 3979 // all the regions. This is a nicer way of ensuring this rather 3980 // than iterating over the regions and fixing them. In fact, the 3981 // GC time stamp increment here also ensures that 3982 // saved_mark_word() will return top() between pauses, i.e., 3983 // during concurrent refinement. So we don't need the 3984 // is_gc_active() check to decided which top to use when 3985 // scanning cards (see CR 7039627). 3986 increment_gc_time_stamp(); 3987 3988 verify_after_gc(); 3989 check_bitmaps("GC End"); 3990 3991 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 3992 ref_processor_stw()->verify_no_references_recorded(); 3993 3994 // CM reference discovery will be re-enabled if necessary. 3995 } 3996 3997 // We should do this after we potentially expand the heap so 3998 // that all the COMMIT events are generated before the end GC 3999 // event, and after we retire the GC alloc regions so that all 4000 // RETIRE events are generated before the end GC event. 4001 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4002 4003 #ifdef TRACESPINNING 4004 ParallelTaskTerminator::print_termination_counts(); 4005 #endif 4006 4007 gc_epilogue(false); 4008 } 4009 4010 // Print the remainder of the GC log output. 4011 log_gc_footer(os::elapsedTime() - pause_start_sec); 4012 4013 // It is not yet to safe to tell the concurrent mark to 4014 // start as we have some optional output below. We don't want the 4015 // output from the concurrent mark thread interfering with this 4016 // logging output either. 4017 4018 _hrm.verify_optional(); 4019 verify_region_sets_optional(); 4020 4021 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats()); 4022 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4023 4024 print_heap_after_gc(); 4025 trace_heap_after_gc(_gc_tracer_stw); 4026 4027 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4028 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4029 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4030 // before any GC notifications are raised. 4031 g1mm()->update_sizes(); 4032 4033 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4034 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4035 _gc_timer_stw->register_gc_end(); 4036 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4037 } 4038 // It should now be safe to tell the concurrent mark thread to start 4039 // without its logging output interfering with the logging output 4040 // that came from the pause. 4041 4042 if (should_start_conc_mark) { 4043 // CAUTION: after the doConcurrentMark() call below, 4044 // the concurrent marking thread(s) could be running 4045 // concurrently with us. Make sure that anything after 4046 // this point does not assume that we are the only GC thread 4047 // running. Note: of course, the actual marking work will 4048 // not start until the safepoint itself is released in 4049 // SuspendibleThreadSet::desynchronize(). 4050 doConcurrentMark(); 4051 } 4052 4053 return true; 4054 } 4055 4056 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4057 _drain_in_progress = false; 4058 set_evac_failure_closure(cl); 4059 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4060 } 4061 4062 void G1CollectedHeap::finalize_for_evac_failure() { 4063 assert(_evac_failure_scan_stack != NULL && 4064 _evac_failure_scan_stack->length() == 0, 4065 "Postcondition"); 4066 assert(!_drain_in_progress, "Postcondition"); 4067 delete _evac_failure_scan_stack; 4068 _evac_failure_scan_stack = NULL; 4069 } 4070 4071 void G1CollectedHeap::remove_self_forwarding_pointers() { 4072 double remove_self_forwards_start = os::elapsedTime(); 4073 4074 set_par_threads(); 4075 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4076 workers()->run_task(&rsfp_task); 4077 set_par_threads(0); 4078 4079 // Now restore saved marks, if any. 4080 assert(_objs_with_preserved_marks.size() == 4081 _preserved_marks_of_objs.size(), "Both or none."); 4082 while (!_objs_with_preserved_marks.is_empty()) { 4083 oop obj = _objs_with_preserved_marks.pop(); 4084 markOop m = _preserved_marks_of_objs.pop(); 4085 obj->set_mark(m); 4086 } 4087 _objs_with_preserved_marks.clear(true); 4088 _preserved_marks_of_objs.clear(true); 4089 4090 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4091 } 4092 4093 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4094 _evac_failure_scan_stack->push(obj); 4095 } 4096 4097 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4098 assert(_evac_failure_scan_stack != NULL, "precondition"); 4099 4100 while (_evac_failure_scan_stack->length() > 0) { 4101 oop obj = _evac_failure_scan_stack->pop(); 4102 _evac_failure_closure->set_region(heap_region_containing(obj)); 4103 obj->oop_iterate_backwards(_evac_failure_closure); 4104 } 4105 } 4106 4107 oop 4108 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4109 oop old) { 4110 assert(obj_in_cs(old), 4111 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4112 (HeapWord*) old)); 4113 markOop m = old->mark(); 4114 oop forward_ptr = old->forward_to_atomic(old); 4115 if (forward_ptr == NULL) { 4116 // Forward-to-self succeeded. 4117 assert(_par_scan_state != NULL, "par scan state"); 4118 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4119 uint queue_num = _par_scan_state->queue_num(); 4120 4121 _evacuation_failed = true; 4122 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4123 if (_evac_failure_closure != cl) { 4124 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4125 assert(!_drain_in_progress, 4126 "Should only be true while someone holds the lock."); 4127 // Set the global evac-failure closure to the current thread's. 4128 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4129 set_evac_failure_closure(cl); 4130 // Now do the common part. 4131 handle_evacuation_failure_common(old, m); 4132 // Reset to NULL. 4133 set_evac_failure_closure(NULL); 4134 } else { 4135 // The lock is already held, and this is recursive. 4136 assert(_drain_in_progress, "This should only be the recursive case."); 4137 handle_evacuation_failure_common(old, m); 4138 } 4139 return old; 4140 } else { 4141 // Forward-to-self failed. Either someone else managed to allocate 4142 // space for this object (old != forward_ptr) or they beat us in 4143 // self-forwarding it (old == forward_ptr). 4144 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4145 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4146 "should not be in the CSet", 4147 (HeapWord*) old, (HeapWord*) forward_ptr)); 4148 return forward_ptr; 4149 } 4150 } 4151 4152 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4153 preserve_mark_if_necessary(old, m); 4154 4155 HeapRegion* r = heap_region_containing(old); 4156 if (!r->evacuation_failed()) { 4157 r->set_evacuation_failed(true); 4158 _hr_printer.evac_failure(r); 4159 } 4160 4161 push_on_evac_failure_scan_stack(old); 4162 4163 if (!_drain_in_progress) { 4164 // prevent recursion in copy_to_survivor_space() 4165 _drain_in_progress = true; 4166 drain_evac_failure_scan_stack(); 4167 _drain_in_progress = false; 4168 } 4169 } 4170 4171 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4172 assert(evacuation_failed(), "Oversaving!"); 4173 // We want to call the "for_promotion_failure" version only in the 4174 // case of a promotion failure. 4175 if (m->must_be_preserved_for_promotion_failure(obj)) { 4176 _objs_with_preserved_marks.push(obj); 4177 _preserved_marks_of_objs.push(m); 4178 } 4179 } 4180 4181 void G1ParCopyHelper::mark_object(oop obj) { 4182 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); 4183 4184 // We know that the object is not moving so it's safe to read its size. 4185 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4186 } 4187 4188 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4189 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4190 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4191 assert(from_obj != to_obj, "should not be self-forwarded"); 4192 4193 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); 4194 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); 4195 4196 // The object might be in the process of being copied by another 4197 // worker so we cannot trust that its to-space image is 4198 // well-formed. So we have to read its size from its from-space 4199 // image which we know should not be changing. 4200 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4201 } 4202 4203 template <class T> 4204 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4205 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4206 _scanned_klass->record_modified_oops(); 4207 } 4208 } 4209 4210 template <G1Barrier barrier, G1Mark do_mark_object> 4211 template <class T> 4212 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4213 T heap_oop = oopDesc::load_heap_oop(p); 4214 4215 if (oopDesc::is_null(heap_oop)) { 4216 return; 4217 } 4218 4219 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4220 4221 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4222 4223 const InCSetState state = _g1->in_cset_state(obj); 4224 if (state.is_in_cset()) { 4225 oop forwardee; 4226 markOop m = obj->mark(); 4227 if (m->is_marked()) { 4228 forwardee = (oop) m->decode_pointer(); 4229 } else { 4230 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m); 4231 } 4232 assert(forwardee != NULL, "forwardee should not be NULL"); 4233 oopDesc::encode_store_heap_oop(p, forwardee); 4234 if (do_mark_object != G1MarkNone && forwardee != obj) { 4235 // If the object is self-forwarded we don't need to explicitly 4236 // mark it, the evacuation failure protocol will do so. 4237 mark_forwarded_object(obj, forwardee); 4238 } 4239 4240 if (barrier == G1BarrierKlass) { 4241 do_klass_barrier(p, forwardee); 4242 } 4243 } else { 4244 if (state.is_humongous()) { 4245 _g1->set_humongous_is_live(obj); 4246 } 4247 // The object is not in collection set. If we're a root scanning 4248 // closure during an initial mark pause then attempt to mark the object. 4249 if (do_mark_object == G1MarkFromRoot) { 4250 mark_object(obj); 4251 } 4252 } 4253 4254 if (barrier == G1BarrierEvac) { 4255 _par_scan_state->update_rs(_from, p, _worker_id); 4256 } 4257 } 4258 4259 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p); 4260 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p); 4261 4262 class G1ParEvacuateFollowersClosure : public VoidClosure { 4263 protected: 4264 G1CollectedHeap* _g1h; 4265 G1ParScanThreadState* _par_scan_state; 4266 RefToScanQueueSet* _queues; 4267 ParallelTaskTerminator* _terminator; 4268 4269 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4270 RefToScanQueueSet* queues() { return _queues; } 4271 ParallelTaskTerminator* terminator() { return _terminator; } 4272 4273 public: 4274 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4275 G1ParScanThreadState* par_scan_state, 4276 RefToScanQueueSet* queues, 4277 ParallelTaskTerminator* terminator) 4278 : _g1h(g1h), _par_scan_state(par_scan_state), 4279 _queues(queues), _terminator(terminator) {} 4280 4281 void do_void(); 4282 4283 private: 4284 inline bool offer_termination(); 4285 }; 4286 4287 bool G1ParEvacuateFollowersClosure::offer_termination() { 4288 G1ParScanThreadState* const pss = par_scan_state(); 4289 pss->start_term_time(); 4290 const bool res = terminator()->offer_termination(); 4291 pss->end_term_time(); 4292 return res; 4293 } 4294 4295 void G1ParEvacuateFollowersClosure::do_void() { 4296 G1ParScanThreadState* const pss = par_scan_state(); 4297 pss->trim_queue(); 4298 do { 4299 pss->steal_and_trim_queue(queues()); 4300 } while (!offer_termination()); 4301 } 4302 4303 class G1KlassScanClosure : public KlassClosure { 4304 G1ParCopyHelper* _closure; 4305 bool _process_only_dirty; 4306 int _count; 4307 public: 4308 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4309 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4310 void do_klass(Klass* klass) { 4311 // If the klass has not been dirtied we know that there's 4312 // no references into the young gen and we can skip it. 4313 if (!_process_only_dirty || klass->has_modified_oops()) { 4314 // Clean the klass since we're going to scavenge all the metadata. 4315 klass->clear_modified_oops(); 4316 4317 // Tell the closure that this klass is the Klass to scavenge 4318 // and is the one to dirty if oops are left pointing into the young gen. 4319 _closure->set_scanned_klass(klass); 4320 4321 klass->oops_do(_closure); 4322 4323 _closure->set_scanned_klass(NULL); 4324 } 4325 _count++; 4326 } 4327 }; 4328 4329 class G1ParTask : public AbstractGangTask { 4330 protected: 4331 G1CollectedHeap* _g1h; 4332 RefToScanQueueSet *_queues; 4333 G1RootProcessor* _root_processor; 4334 ParallelTaskTerminator _terminator; 4335 uint _n_workers; 4336 4337 Mutex _stats_lock; 4338 Mutex* stats_lock() { return &_stats_lock; } 4339 4340 public: 4341 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor) 4342 : AbstractGangTask("G1 collection"), 4343 _g1h(g1h), 4344 _queues(task_queues), 4345 _root_processor(root_processor), 4346 _terminator(0, _queues), 4347 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4348 {} 4349 4350 RefToScanQueueSet* queues() { return _queues; } 4351 4352 RefToScanQueue *work_queue(int i) { 4353 return queues()->queue(i); 4354 } 4355 4356 ParallelTaskTerminator* terminator() { return &_terminator; } 4357 4358 virtual void set_for_termination(int active_workers) { 4359 _root_processor->set_num_workers(active_workers); 4360 terminator()->reset_for_reuse(active_workers); 4361 _n_workers = active_workers; 4362 } 4363 4364 // Helps out with CLD processing. 4365 // 4366 // During InitialMark we need to: 4367 // 1) Scavenge all CLDs for the young GC. 4368 // 2) Mark all objects directly reachable from strong CLDs. 4369 template <G1Mark do_mark_object> 4370 class G1CLDClosure : public CLDClosure { 4371 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure; 4372 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure; 4373 G1KlassScanClosure _klass_in_cld_closure; 4374 bool _claim; 4375 4376 public: 4377 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure, 4378 bool only_young, bool claim) 4379 : _oop_closure(oop_closure), 4380 _oop_in_klass_closure(oop_closure->g1(), 4381 oop_closure->pss(), 4382 oop_closure->rp()), 4383 _klass_in_cld_closure(&_oop_in_klass_closure, only_young), 4384 _claim(claim) { 4385 4386 } 4387 4388 void do_cld(ClassLoaderData* cld) { 4389 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim); 4390 } 4391 }; 4392 4393 void work(uint worker_id) { 4394 if (worker_id >= _n_workers) return; // no work needed this round 4395 4396 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime()); 4397 4398 { 4399 ResourceMark rm; 4400 HandleMark hm; 4401 4402 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4403 4404 G1ParScanThreadState pss(_g1h, worker_id, rp); 4405 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 4406 4407 pss.set_evac_failure_closure(&evac_failure_cl); 4408 4409 bool only_young = _g1h->g1_policy()->gcs_are_young(); 4410 4411 // Non-IM young GC. 4412 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp); 4413 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl, 4414 only_young, // Only process dirty klasses. 4415 false); // No need to claim CLDs. 4416 // IM young GC. 4417 // Strong roots closures. 4418 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp); 4419 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl, 4420 false, // Process all klasses. 4421 true); // Need to claim CLDs. 4422 // Weak roots closures. 4423 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp); 4424 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl, 4425 false, // Process all klasses. 4426 true); // Need to claim CLDs. 4427 4428 OopClosure* strong_root_cl; 4429 OopClosure* weak_root_cl; 4430 CLDClosure* strong_cld_cl; 4431 CLDClosure* weak_cld_cl; 4432 4433 bool trace_metadata = false; 4434 4435 if (_g1h->g1_policy()->during_initial_mark_pause()) { 4436 // We also need to mark copied objects. 4437 strong_root_cl = &scan_mark_root_cl; 4438 strong_cld_cl = &scan_mark_cld_cl; 4439 if (ClassUnloadingWithConcurrentMark) { 4440 weak_root_cl = &scan_mark_weak_root_cl; 4441 weak_cld_cl = &scan_mark_weak_cld_cl; 4442 trace_metadata = true; 4443 } else { 4444 weak_root_cl = &scan_mark_root_cl; 4445 weak_cld_cl = &scan_mark_cld_cl; 4446 } 4447 } else { 4448 strong_root_cl = &scan_only_root_cl; 4449 weak_root_cl = &scan_only_root_cl; 4450 strong_cld_cl = &scan_only_cld_cl; 4451 weak_cld_cl = &scan_only_cld_cl; 4452 } 4453 4454 pss.start_strong_roots(); 4455 4456 _root_processor->evacuate_roots(strong_root_cl, 4457 weak_root_cl, 4458 strong_cld_cl, 4459 weak_cld_cl, 4460 trace_metadata, 4461 worker_id); 4462 4463 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4464 _root_processor->scan_remembered_sets(&push_heap_rs_cl, 4465 weak_root_cl, 4466 worker_id); 4467 pss.end_strong_roots(); 4468 4469 { 4470 double start = os::elapsedTime(); 4471 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4472 evac.do_void(); 4473 double elapsed_sec = os::elapsedTime() - start; 4474 double term_sec = pss.term_time(); 4475 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 4476 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 4477 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts()); 4478 } 4479 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4480 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4481 4482 if (PrintTerminationStats) { 4483 MutexLocker x(stats_lock()); 4484 pss.print_termination_stats(worker_id); 4485 } 4486 4487 assert(pss.queue_is_empty(), "should be empty"); 4488 4489 // Close the inner scope so that the ResourceMark and HandleMark 4490 // destructors are executed here and are included as part of the 4491 // "GC Worker Time". 4492 } 4493 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 4494 } 4495 }; 4496 4497 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4498 private: 4499 BoolObjectClosure* _is_alive; 4500 int _initial_string_table_size; 4501 int _initial_symbol_table_size; 4502 4503 bool _process_strings; 4504 int _strings_processed; 4505 int _strings_removed; 4506 4507 bool _process_symbols; 4508 int _symbols_processed; 4509 int _symbols_removed; 4510 4511 public: 4512 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4513 AbstractGangTask("String/Symbol Unlinking"), 4514 _is_alive(is_alive), 4515 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4516 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4517 4518 _initial_string_table_size = StringTable::the_table()->table_size(); 4519 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4520 if (process_strings) { 4521 StringTable::clear_parallel_claimed_index(); 4522 } 4523 if (process_symbols) { 4524 SymbolTable::clear_parallel_claimed_index(); 4525 } 4526 } 4527 4528 ~G1StringSymbolTableUnlinkTask() { 4529 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4530 err_msg("claim value %d after unlink less than initial string table size %d", 4531 StringTable::parallel_claimed_index(), _initial_string_table_size)); 4532 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4533 err_msg("claim value %d after unlink less than initial symbol table size %d", 4534 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 4535 4536 if (G1TraceStringSymbolTableScrubbing) { 4537 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4538 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 4539 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 4540 strings_processed(), strings_removed(), 4541 symbols_processed(), symbols_removed()); 4542 } 4543 } 4544 4545 void work(uint worker_id) { 4546 int strings_processed = 0; 4547 int strings_removed = 0; 4548 int symbols_processed = 0; 4549 int symbols_removed = 0; 4550 if (_process_strings) { 4551 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4552 Atomic::add(strings_processed, &_strings_processed); 4553 Atomic::add(strings_removed, &_strings_removed); 4554 } 4555 if (_process_symbols) { 4556 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 4557 Atomic::add(symbols_processed, &_symbols_processed); 4558 Atomic::add(symbols_removed, &_symbols_removed); 4559 } 4560 } 4561 4562 size_t strings_processed() const { return (size_t)_strings_processed; } 4563 size_t strings_removed() const { return (size_t)_strings_removed; } 4564 4565 size_t symbols_processed() const { return (size_t)_symbols_processed; } 4566 size_t symbols_removed() const { return (size_t)_symbols_removed; } 4567 }; 4568 4569 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 4570 private: 4571 static Monitor* _lock; 4572 4573 BoolObjectClosure* const _is_alive; 4574 const bool _unloading_occurred; 4575 const uint _num_workers; 4576 4577 // Variables used to claim nmethods. 4578 nmethod* _first_nmethod; 4579 volatile nmethod* _claimed_nmethod; 4580 4581 // The list of nmethods that need to be processed by the second pass. 4582 volatile nmethod* _postponed_list; 4583 volatile uint _num_entered_barrier; 4584 4585 public: 4586 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 4587 _is_alive(is_alive), 4588 _unloading_occurred(unloading_occurred), 4589 _num_workers(num_workers), 4590 _first_nmethod(NULL), 4591 _claimed_nmethod(NULL), 4592 _postponed_list(NULL), 4593 _num_entered_barrier(0) 4594 { 4595 nmethod::increase_unloading_clock(); 4596 // Get first alive nmethod 4597 NMethodIterator iter = NMethodIterator(); 4598 if(iter.next_alive()) { 4599 _first_nmethod = iter.method(); 4600 } 4601 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 4602 } 4603 4604 ~G1CodeCacheUnloadingTask() { 4605 CodeCache::verify_clean_inline_caches(); 4606 4607 CodeCache::set_needs_cache_clean(false); 4608 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 4609 4610 CodeCache::verify_icholder_relocations(); 4611 } 4612 4613 private: 4614 void add_to_postponed_list(nmethod* nm) { 4615 nmethod* old; 4616 do { 4617 old = (nmethod*)_postponed_list; 4618 nm->set_unloading_next(old); 4619 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 4620 } 4621 4622 void clean_nmethod(nmethod* nm) { 4623 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 4624 4625 if (postponed) { 4626 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 4627 add_to_postponed_list(nm); 4628 } 4629 4630 // Mark that this thread has been cleaned/unloaded. 4631 // After this call, it will be safe to ask if this nmethod was unloaded or not. 4632 nm->set_unloading_clock(nmethod::global_unloading_clock()); 4633 } 4634 4635 void clean_nmethod_postponed(nmethod* nm) { 4636 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 4637 } 4638 4639 static const int MaxClaimNmethods = 16; 4640 4641 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 4642 nmethod* first; 4643 NMethodIterator last; 4644 4645 do { 4646 *num_claimed_nmethods = 0; 4647 4648 first = (nmethod*)_claimed_nmethod; 4649 last = NMethodIterator(first); 4650 4651 if (first != NULL) { 4652 4653 for (int i = 0; i < MaxClaimNmethods; i++) { 4654 if (!last.next_alive()) { 4655 break; 4656 } 4657 claimed_nmethods[i] = last.method(); 4658 (*num_claimed_nmethods)++; 4659 } 4660 } 4661 4662 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 4663 } 4664 4665 nmethod* claim_postponed_nmethod() { 4666 nmethod* claim; 4667 nmethod* next; 4668 4669 do { 4670 claim = (nmethod*)_postponed_list; 4671 if (claim == NULL) { 4672 return NULL; 4673 } 4674 4675 next = claim->unloading_next(); 4676 4677 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 4678 4679 return claim; 4680 } 4681 4682 public: 4683 // Mark that we're done with the first pass of nmethod cleaning. 4684 void barrier_mark(uint worker_id) { 4685 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4686 _num_entered_barrier++; 4687 if (_num_entered_barrier == _num_workers) { 4688 ml.notify_all(); 4689 } 4690 } 4691 4692 // See if we have to wait for the other workers to 4693 // finish their first-pass nmethod cleaning work. 4694 void barrier_wait(uint worker_id) { 4695 if (_num_entered_barrier < _num_workers) { 4696 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4697 while (_num_entered_barrier < _num_workers) { 4698 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 4699 } 4700 } 4701 } 4702 4703 // Cleaning and unloading of nmethods. Some work has to be postponed 4704 // to the second pass, when we know which nmethods survive. 4705 void work_first_pass(uint worker_id) { 4706 // The first nmethods is claimed by the first worker. 4707 if (worker_id == 0 && _first_nmethod != NULL) { 4708 clean_nmethod(_first_nmethod); 4709 _first_nmethod = NULL; 4710 } 4711 4712 int num_claimed_nmethods; 4713 nmethod* claimed_nmethods[MaxClaimNmethods]; 4714 4715 while (true) { 4716 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 4717 4718 if (num_claimed_nmethods == 0) { 4719 break; 4720 } 4721 4722 for (int i = 0; i < num_claimed_nmethods; i++) { 4723 clean_nmethod(claimed_nmethods[i]); 4724 } 4725 } 4726 } 4727 4728 void work_second_pass(uint worker_id) { 4729 nmethod* nm; 4730 // Take care of postponed nmethods. 4731 while ((nm = claim_postponed_nmethod()) != NULL) { 4732 clean_nmethod_postponed(nm); 4733 } 4734 } 4735 }; 4736 4737 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 4738 4739 class G1KlassCleaningTask : public StackObj { 4740 BoolObjectClosure* _is_alive; 4741 volatile jint _clean_klass_tree_claimed; 4742 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 4743 4744 public: 4745 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 4746 _is_alive(is_alive), 4747 _clean_klass_tree_claimed(0), 4748 _klass_iterator() { 4749 } 4750 4751 private: 4752 bool claim_clean_klass_tree_task() { 4753 if (_clean_klass_tree_claimed) { 4754 return false; 4755 } 4756 4757 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 4758 } 4759 4760 InstanceKlass* claim_next_klass() { 4761 Klass* klass; 4762 do { 4763 klass =_klass_iterator.next_klass(); 4764 } while (klass != NULL && !klass->oop_is_instance()); 4765 4766 return (InstanceKlass*)klass; 4767 } 4768 4769 public: 4770 4771 void clean_klass(InstanceKlass* ik) { 4772 ik->clean_implementors_list(_is_alive); 4773 ik->clean_method_data(_is_alive); 4774 4775 // G1 specific cleanup work that has 4776 // been moved here to be done in parallel. 4777 ik->clean_dependent_nmethods(); 4778 } 4779 4780 void work() { 4781 ResourceMark rm; 4782 4783 // One worker will clean the subklass/sibling klass tree. 4784 if (claim_clean_klass_tree_task()) { 4785 Klass::clean_subklass_tree(_is_alive); 4786 } 4787 4788 // All workers will help cleaning the classes, 4789 InstanceKlass* klass; 4790 while ((klass = claim_next_klass()) != NULL) { 4791 clean_klass(klass); 4792 } 4793 } 4794 }; 4795 4796 // To minimize the remark pause times, the tasks below are done in parallel. 4797 class G1ParallelCleaningTask : public AbstractGangTask { 4798 private: 4799 G1StringSymbolTableUnlinkTask _string_symbol_task; 4800 G1CodeCacheUnloadingTask _code_cache_task; 4801 G1KlassCleaningTask _klass_cleaning_task; 4802 4803 public: 4804 // The constructor is run in the VMThread. 4805 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 4806 AbstractGangTask("Parallel Cleaning"), 4807 _string_symbol_task(is_alive, process_strings, process_symbols), 4808 _code_cache_task(num_workers, is_alive, unloading_occurred), 4809 _klass_cleaning_task(is_alive) { 4810 } 4811 4812 // The parallel work done by all worker threads. 4813 void work(uint worker_id) { 4814 // Do first pass of code cache cleaning. 4815 _code_cache_task.work_first_pass(worker_id); 4816 4817 // Let the threads mark that the first pass is done. 4818 _code_cache_task.barrier_mark(worker_id); 4819 4820 // Clean the Strings and Symbols. 4821 _string_symbol_task.work(worker_id); 4822 4823 // Wait for all workers to finish the first code cache cleaning pass. 4824 _code_cache_task.barrier_wait(worker_id); 4825 4826 // Do the second code cache cleaning work, which realize on 4827 // the liveness information gathered during the first pass. 4828 _code_cache_task.work_second_pass(worker_id); 4829 4830 // Clean all klasses that were not unloaded. 4831 _klass_cleaning_task.work(); 4832 } 4833 }; 4834 4835 4836 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 4837 bool process_strings, 4838 bool process_symbols, 4839 bool class_unloading_occurred) { 4840 uint n_workers = workers()->active_workers(); 4841 4842 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 4843 n_workers, class_unloading_occurred); 4844 set_par_threads(n_workers); 4845 workers()->run_task(&g1_unlink_task); 4846 set_par_threads(0); 4847 } 4848 4849 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 4850 bool process_strings, bool process_symbols) { 4851 { 4852 uint n_workers = _g1h->workers()->active_workers(); 4853 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 4854 set_par_threads(n_workers); 4855 workers()->run_task(&g1_unlink_task); 4856 set_par_threads(0); 4857 } 4858 4859 if (G1StringDedup::is_enabled()) { 4860 G1StringDedup::unlink(is_alive); 4861 } 4862 } 4863 4864 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 4865 private: 4866 DirtyCardQueueSet* _queue; 4867 public: 4868 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 4869 4870 virtual void work(uint worker_id) { 4871 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4872 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 4873 4874 RedirtyLoggedCardTableEntryClosure cl; 4875 _queue->par_apply_closure_to_all_completed_buffers(&cl); 4876 4877 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed()); 4878 } 4879 }; 4880 4881 void G1CollectedHeap::redirty_logged_cards() { 4882 double redirty_logged_cards_start = os::elapsedTime(); 4883 4884 uint n_workers = _g1h->workers()->active_workers(); 4885 4886 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 4887 dirty_card_queue_set().reset_for_par_iteration(); 4888 set_par_threads(n_workers); 4889 workers()->run_task(&redirty_task); 4890 set_par_threads(0); 4891 4892 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 4893 dcq.merge_bufferlists(&dirty_card_queue_set()); 4894 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 4895 4896 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 4897 } 4898 4899 // Weak Reference Processing support 4900 4901 // An always "is_alive" closure that is used to preserve referents. 4902 // If the object is non-null then it's alive. Used in the preservation 4903 // of referent objects that are pointed to by reference objects 4904 // discovered by the CM ref processor. 4905 class G1AlwaysAliveClosure: public BoolObjectClosure { 4906 G1CollectedHeap* _g1; 4907 public: 4908 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4909 bool do_object_b(oop p) { 4910 if (p != NULL) { 4911 return true; 4912 } 4913 return false; 4914 } 4915 }; 4916 4917 bool G1STWIsAliveClosure::do_object_b(oop p) { 4918 // An object is reachable if it is outside the collection set, 4919 // or is inside and copied. 4920 return !_g1->obj_in_cs(p) || p->is_forwarded(); 4921 } 4922 4923 // Non Copying Keep Alive closure 4924 class G1KeepAliveClosure: public OopClosure { 4925 G1CollectedHeap* _g1; 4926 public: 4927 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4928 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 4929 void do_oop(oop* p) { 4930 oop obj = *p; 4931 assert(obj != NULL, "the caller should have filtered out NULL values"); 4932 4933 const InCSetState cset_state = _g1->in_cset_state(obj); 4934 if (!cset_state.is_in_cset_or_humongous()) { 4935 return; 4936 } 4937 if (cset_state.is_in_cset()) { 4938 assert( obj->is_forwarded(), "invariant" ); 4939 *p = obj->forwardee(); 4940 } else { 4941 assert(!obj->is_forwarded(), "invariant" ); 4942 assert(cset_state.is_humongous(), 4943 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value())); 4944 _g1->set_humongous_is_live(obj); 4945 } 4946 } 4947 }; 4948 4949 // Copying Keep Alive closure - can be called from both 4950 // serial and parallel code as long as different worker 4951 // threads utilize different G1ParScanThreadState instances 4952 // and different queues. 4953 4954 class G1CopyingKeepAliveClosure: public OopClosure { 4955 G1CollectedHeap* _g1h; 4956 OopClosure* _copy_non_heap_obj_cl; 4957 G1ParScanThreadState* _par_scan_state; 4958 4959 public: 4960 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 4961 OopClosure* non_heap_obj_cl, 4962 G1ParScanThreadState* pss): 4963 _g1h(g1h), 4964 _copy_non_heap_obj_cl(non_heap_obj_cl), 4965 _par_scan_state(pss) 4966 {} 4967 4968 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 4969 virtual void do_oop( oop* p) { do_oop_work(p); } 4970 4971 template <class T> void do_oop_work(T* p) { 4972 oop obj = oopDesc::load_decode_heap_oop(p); 4973 4974 if (_g1h->is_in_cset_or_humongous(obj)) { 4975 // If the referent object has been forwarded (either copied 4976 // to a new location or to itself in the event of an 4977 // evacuation failure) then we need to update the reference 4978 // field and, if both reference and referent are in the G1 4979 // heap, update the RSet for the referent. 4980 // 4981 // If the referent has not been forwarded then we have to keep 4982 // it alive by policy. Therefore we have copy the referent. 4983 // 4984 // If the reference field is in the G1 heap then we can push 4985 // on the PSS queue. When the queue is drained (after each 4986 // phase of reference processing) the object and it's followers 4987 // will be copied, the reference field set to point to the 4988 // new location, and the RSet updated. Otherwise we need to 4989 // use the the non-heap or metadata closures directly to copy 4990 // the referent object and update the pointer, while avoiding 4991 // updating the RSet. 4992 4993 if (_g1h->is_in_g1_reserved(p)) { 4994 _par_scan_state->push_on_queue(p); 4995 } else { 4996 assert(!Metaspace::contains((const void*)p), 4997 err_msg("Unexpectedly found a pointer from metadata: " 4998 PTR_FORMAT, p)); 4999 _copy_non_heap_obj_cl->do_oop(p); 5000 } 5001 } 5002 } 5003 }; 5004 5005 // Serial drain queue closure. Called as the 'complete_gc' 5006 // closure for each discovered list in some of the 5007 // reference processing phases. 5008 5009 class G1STWDrainQueueClosure: public VoidClosure { 5010 protected: 5011 G1CollectedHeap* _g1h; 5012 G1ParScanThreadState* _par_scan_state; 5013 5014 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5015 5016 public: 5017 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5018 _g1h(g1h), 5019 _par_scan_state(pss) 5020 { } 5021 5022 void do_void() { 5023 G1ParScanThreadState* const pss = par_scan_state(); 5024 pss->trim_queue(); 5025 } 5026 }; 5027 5028 // Parallel Reference Processing closures 5029 5030 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5031 // processing during G1 evacuation pauses. 5032 5033 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5034 private: 5035 G1CollectedHeap* _g1h; 5036 RefToScanQueueSet* _queues; 5037 FlexibleWorkGang* _workers; 5038 int _active_workers; 5039 5040 public: 5041 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5042 FlexibleWorkGang* workers, 5043 RefToScanQueueSet *task_queues, 5044 int n_workers) : 5045 _g1h(g1h), 5046 _queues(task_queues), 5047 _workers(workers), 5048 _active_workers(n_workers) 5049 { 5050 assert(n_workers > 0, "shouldn't call this otherwise"); 5051 } 5052 5053 // Executes the given task using concurrent marking worker threads. 5054 virtual void execute(ProcessTask& task); 5055 virtual void execute(EnqueueTask& task); 5056 }; 5057 5058 // Gang task for possibly parallel reference processing 5059 5060 class G1STWRefProcTaskProxy: public AbstractGangTask { 5061 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5062 ProcessTask& _proc_task; 5063 G1CollectedHeap* _g1h; 5064 RefToScanQueueSet *_task_queues; 5065 ParallelTaskTerminator* _terminator; 5066 5067 public: 5068 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5069 G1CollectedHeap* g1h, 5070 RefToScanQueueSet *task_queues, 5071 ParallelTaskTerminator* terminator) : 5072 AbstractGangTask("Process reference objects in parallel"), 5073 _proc_task(proc_task), 5074 _g1h(g1h), 5075 _task_queues(task_queues), 5076 _terminator(terminator) 5077 {} 5078 5079 virtual void work(uint worker_id) { 5080 // The reference processing task executed by a single worker. 5081 ResourceMark rm; 5082 HandleMark hm; 5083 5084 G1STWIsAliveClosure is_alive(_g1h); 5085 5086 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5087 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5088 5089 pss.set_evac_failure_closure(&evac_failure_cl); 5090 5091 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5092 5093 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5094 5095 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5096 5097 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5098 // We also need to mark copied objects. 5099 copy_non_heap_cl = ©_mark_non_heap_cl; 5100 } 5101 5102 // Keep alive closure. 5103 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5104 5105 // Complete GC closure 5106 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5107 5108 // Call the reference processing task's work routine. 5109 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5110 5111 // Note we cannot assert that the refs array is empty here as not all 5112 // of the processing tasks (specifically phase2 - pp2_work) execute 5113 // the complete_gc closure (which ordinarily would drain the queue) so 5114 // the queue may not be empty. 5115 } 5116 }; 5117 5118 // Driver routine for parallel reference processing. 5119 // Creates an instance of the ref processing gang 5120 // task and has the worker threads execute it. 5121 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5122 assert(_workers != NULL, "Need parallel worker threads."); 5123 5124 ParallelTaskTerminator terminator(_active_workers, _queues); 5125 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5126 5127 _g1h->set_par_threads(_active_workers); 5128 _workers->run_task(&proc_task_proxy); 5129 _g1h->set_par_threads(0); 5130 } 5131 5132 // Gang task for parallel reference enqueueing. 5133 5134 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5135 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5136 EnqueueTask& _enq_task; 5137 5138 public: 5139 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5140 AbstractGangTask("Enqueue reference objects in parallel"), 5141 _enq_task(enq_task) 5142 { } 5143 5144 virtual void work(uint worker_id) { 5145 _enq_task.work(worker_id); 5146 } 5147 }; 5148 5149 // Driver routine for parallel reference enqueueing. 5150 // Creates an instance of the ref enqueueing gang 5151 // task and has the worker threads execute it. 5152 5153 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5154 assert(_workers != NULL, "Need parallel worker threads."); 5155 5156 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5157 5158 _g1h->set_par_threads(_active_workers); 5159 _workers->run_task(&enq_task_proxy); 5160 _g1h->set_par_threads(0); 5161 } 5162 5163 // End of weak reference support closures 5164 5165 // Abstract task used to preserve (i.e. copy) any referent objects 5166 // that are in the collection set and are pointed to by reference 5167 // objects discovered by the CM ref processor. 5168 5169 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5170 protected: 5171 G1CollectedHeap* _g1h; 5172 RefToScanQueueSet *_queues; 5173 ParallelTaskTerminator _terminator; 5174 uint _n_workers; 5175 5176 public: 5177 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5178 AbstractGangTask("ParPreserveCMReferents"), 5179 _g1h(g1h), 5180 _queues(task_queues), 5181 _terminator(workers, _queues), 5182 _n_workers(workers) 5183 { } 5184 5185 void work(uint worker_id) { 5186 ResourceMark rm; 5187 HandleMark hm; 5188 5189 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5190 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5191 5192 pss.set_evac_failure_closure(&evac_failure_cl); 5193 5194 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5195 5196 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5197 5198 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5199 5200 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5201 5202 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5203 // We also need to mark copied objects. 5204 copy_non_heap_cl = ©_mark_non_heap_cl; 5205 } 5206 5207 // Is alive closure 5208 G1AlwaysAliveClosure always_alive(_g1h); 5209 5210 // Copying keep alive closure. Applied to referent objects that need 5211 // to be copied. 5212 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5213 5214 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5215 5216 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5217 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5218 5219 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5220 // So this must be true - but assert just in case someone decides to 5221 // change the worker ids. 5222 assert(worker_id < limit, "sanity"); 5223 assert(!rp->discovery_is_atomic(), "check this code"); 5224 5225 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5226 for (uint idx = worker_id; idx < limit; idx += stride) { 5227 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5228 5229 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5230 while (iter.has_next()) { 5231 // Since discovery is not atomic for the CM ref processor, we 5232 // can see some null referent objects. 5233 iter.load_ptrs(DEBUG_ONLY(true)); 5234 oop ref = iter.obj(); 5235 5236 // This will filter nulls. 5237 if (iter.is_referent_alive()) { 5238 iter.make_referent_alive(); 5239 } 5240 iter.move_to_next(); 5241 } 5242 } 5243 5244 // Drain the queue - which may cause stealing 5245 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5246 drain_queue.do_void(); 5247 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5248 assert(pss.queue_is_empty(), "should be"); 5249 } 5250 }; 5251 5252 // Weak Reference processing during an evacuation pause (part 1). 5253 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5254 double ref_proc_start = os::elapsedTime(); 5255 5256 ReferenceProcessor* rp = _ref_processor_stw; 5257 assert(rp->discovery_enabled(), "should have been enabled"); 5258 5259 // Any reference objects, in the collection set, that were 'discovered' 5260 // by the CM ref processor should have already been copied (either by 5261 // applying the external root copy closure to the discovered lists, or 5262 // by following an RSet entry). 5263 // 5264 // But some of the referents, that are in the collection set, that these 5265 // reference objects point to may not have been copied: the STW ref 5266 // processor would have seen that the reference object had already 5267 // been 'discovered' and would have skipped discovering the reference, 5268 // but would not have treated the reference object as a regular oop. 5269 // As a result the copy closure would not have been applied to the 5270 // referent object. 5271 // 5272 // We need to explicitly copy these referent objects - the references 5273 // will be processed at the end of remarking. 5274 // 5275 // We also need to do this copying before we process the reference 5276 // objects discovered by the STW ref processor in case one of these 5277 // referents points to another object which is also referenced by an 5278 // object discovered by the STW ref processor. 5279 5280 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers"); 5281 5282 set_par_threads(no_of_gc_workers); 5283 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5284 no_of_gc_workers, 5285 _task_queues); 5286 5287 workers()->run_task(&keep_cm_referents); 5288 5289 set_par_threads(0); 5290 5291 // Closure to test whether a referent is alive. 5292 G1STWIsAliveClosure is_alive(this); 5293 5294 // Even when parallel reference processing is enabled, the processing 5295 // of JNI refs is serial and performed serially by the current thread 5296 // rather than by a worker. The following PSS will be used for processing 5297 // JNI refs. 5298 5299 // Use only a single queue for this PSS. 5300 G1ParScanThreadState pss(this, 0, NULL); 5301 5302 // We do not embed a reference processor in the copying/scanning 5303 // closures while we're actually processing the discovered 5304 // reference objects. 5305 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5306 5307 pss.set_evac_failure_closure(&evac_failure_cl); 5308 5309 assert(pss.queue_is_empty(), "pre-condition"); 5310 5311 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5312 5313 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5314 5315 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5316 5317 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5318 // We also need to mark copied objects. 5319 copy_non_heap_cl = ©_mark_non_heap_cl; 5320 } 5321 5322 // Keep alive closure. 5323 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss); 5324 5325 // Serial Complete GC closure 5326 G1STWDrainQueueClosure drain_queue(this, &pss); 5327 5328 // Setup the soft refs policy... 5329 rp->setup_policy(false); 5330 5331 ReferenceProcessorStats stats; 5332 if (!rp->processing_is_mt()) { 5333 // Serial reference processing... 5334 stats = rp->process_discovered_references(&is_alive, 5335 &keep_alive, 5336 &drain_queue, 5337 NULL, 5338 _gc_timer_stw, 5339 _gc_tracer_stw->gc_id()); 5340 } else { 5341 // Parallel reference processing 5342 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5343 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5344 5345 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5346 stats = rp->process_discovered_references(&is_alive, 5347 &keep_alive, 5348 &drain_queue, 5349 &par_task_executor, 5350 _gc_timer_stw, 5351 _gc_tracer_stw->gc_id()); 5352 } 5353 5354 _gc_tracer_stw->report_gc_reference_stats(stats); 5355 5356 // We have completed copying any necessary live referent objects. 5357 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5358 5359 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5360 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5361 } 5362 5363 // Weak Reference processing during an evacuation pause (part 2). 5364 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5365 double ref_enq_start = os::elapsedTime(); 5366 5367 ReferenceProcessor* rp = _ref_processor_stw; 5368 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5369 5370 // Now enqueue any remaining on the discovered lists on to 5371 // the pending list. 5372 if (!rp->processing_is_mt()) { 5373 // Serial reference processing... 5374 rp->enqueue_discovered_references(); 5375 } else { 5376 // Parallel reference enqueueing 5377 5378 assert(no_of_gc_workers == workers()->active_workers(), 5379 "Need to reset active workers"); 5380 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5381 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5382 5383 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5384 rp->enqueue_discovered_references(&par_task_executor); 5385 } 5386 5387 rp->verify_no_references_recorded(); 5388 assert(!rp->discovery_enabled(), "should have been disabled"); 5389 5390 // FIXME 5391 // CM's reference processing also cleans up the string and symbol tables. 5392 // Should we do that here also? We could, but it is a serial operation 5393 // and could significantly increase the pause time. 5394 5395 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5396 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5397 } 5398 5399 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5400 _expand_heap_after_alloc_failure = true; 5401 _evacuation_failed = false; 5402 5403 // Should G1EvacuationFailureALot be in effect for this GC? 5404 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5405 5406 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5407 5408 // Disable the hot card cache. 5409 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5410 hot_card_cache->reset_hot_cache_claimed_index(); 5411 hot_card_cache->set_use_cache(false); 5412 5413 uint n_workers; 5414 n_workers = 5415 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 5416 workers()->active_workers(), 5417 Threads::number_of_non_daemon_threads()); 5418 assert(UseDynamicNumberOfGCThreads || 5419 n_workers == workers()->total_workers(), 5420 "If not dynamic should be using all the workers"); 5421 workers()->set_active_workers(n_workers); 5422 set_par_threads(n_workers); 5423 5424 5425 init_for_evac_failure(NULL); 5426 5427 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5428 double start_par_time_sec = os::elapsedTime(); 5429 double end_par_time_sec; 5430 5431 { 5432 G1RootProcessor root_processor(this); 5433 G1ParTask g1_par_task(this, _task_queues, &root_processor); 5434 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5435 if (g1_policy()->during_initial_mark_pause()) { 5436 ClassLoaderDataGraph::clear_claimed_marks(); 5437 } 5438 5439 // The individual threads will set their evac-failure closures. 5440 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr(); 5441 // These tasks use ShareHeap::_process_strong_tasks 5442 assert(UseDynamicNumberOfGCThreads || 5443 workers()->active_workers() == workers()->total_workers(), 5444 "If not dynamic should be using all the workers"); 5445 workers()->run_task(&g1_par_task); 5446 end_par_time_sec = os::elapsedTime(); 5447 5448 // Closing the inner scope will execute the destructor 5449 // for the G1RootProcessor object. We record the current 5450 // elapsed time before closing the scope so that time 5451 // taken for the destructor is NOT included in the 5452 // reported parallel time. 5453 } 5454 5455 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 5456 5457 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5458 phase_times->record_par_time(par_time_ms); 5459 5460 double code_root_fixup_time_ms = 5461 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5462 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 5463 5464 set_par_threads(0); 5465 5466 // Process any discovered reference objects - we have 5467 // to do this _before_ we retire the GC alloc regions 5468 // as we may have to copy some 'reachable' referent 5469 // objects (and their reachable sub-graphs) that were 5470 // not copied during the pause. 5471 process_discovered_references(n_workers); 5472 5473 if (G1StringDedup::is_enabled()) { 5474 double fixup_start = os::elapsedTime(); 5475 5476 G1STWIsAliveClosure is_alive(this); 5477 G1KeepAliveClosure keep_alive(this); 5478 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times); 5479 5480 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 5481 phase_times->record_string_dedup_fixup_time(fixup_time_ms); 5482 } 5483 5484 _allocator->release_gc_alloc_regions(n_workers, evacuation_info); 5485 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5486 5487 // Reset and re-enable the hot card cache. 5488 // Note the counts for the cards in the regions in the 5489 // collection set are reset when the collection set is freed. 5490 hot_card_cache->reset_hot_cache(); 5491 hot_card_cache->set_use_cache(true); 5492 5493 purge_code_root_memory(); 5494 5495 finalize_for_evac_failure(); 5496 5497 if (evacuation_failed()) { 5498 remove_self_forwarding_pointers(); 5499 5500 // Reset the G1EvacuationFailureALot counters and flags 5501 // Note: the values are reset only when an actual 5502 // evacuation failure occurs. 5503 NOT_PRODUCT(reset_evacuation_should_fail();) 5504 } 5505 5506 // Enqueue any remaining references remaining on the STW 5507 // reference processor's discovered lists. We need to do 5508 // this after the card table is cleaned (and verified) as 5509 // the act of enqueueing entries on to the pending list 5510 // will log these updates (and dirty their associated 5511 // cards). We need these updates logged to update any 5512 // RSets. 5513 enqueue_discovered_references(n_workers); 5514 5515 redirty_logged_cards(); 5516 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5517 } 5518 5519 void G1CollectedHeap::free_region(HeapRegion* hr, 5520 FreeRegionList* free_list, 5521 bool par, 5522 bool locked) { 5523 assert(!hr->is_free(), "the region should not be free"); 5524 assert(!hr->is_empty(), "the region should not be empty"); 5525 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 5526 assert(free_list != NULL, "pre-condition"); 5527 5528 if (G1VerifyBitmaps) { 5529 MemRegion mr(hr->bottom(), hr->end()); 5530 concurrent_mark()->clearRangePrevBitmap(mr); 5531 } 5532 5533 // Clear the card counts for this region. 5534 // Note: we only need to do this if the region is not young 5535 // (since we don't refine cards in young regions). 5536 if (!hr->is_young()) { 5537 _cg1r->hot_card_cache()->reset_card_counts(hr); 5538 } 5539 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5540 free_list->add_ordered(hr); 5541 } 5542 5543 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5544 FreeRegionList* free_list, 5545 bool par) { 5546 assert(hr->is_starts_humongous(), "this is only for starts humongous regions"); 5547 assert(free_list != NULL, "pre-condition"); 5548 5549 size_t hr_capacity = hr->capacity(); 5550 // We need to read this before we make the region non-humongous, 5551 // otherwise the information will be gone. 5552 uint last_index = hr->last_hc_index(); 5553 hr->clear_humongous(); 5554 free_region(hr, free_list, par); 5555 5556 uint i = hr->hrm_index() + 1; 5557 while (i < last_index) { 5558 HeapRegion* curr_hr = region_at(i); 5559 assert(curr_hr->is_continues_humongous(), "invariant"); 5560 curr_hr->clear_humongous(); 5561 free_region(curr_hr, free_list, par); 5562 i += 1; 5563 } 5564 } 5565 5566 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 5567 const HeapRegionSetCount& humongous_regions_removed) { 5568 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5569 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5570 _old_set.bulk_remove(old_regions_removed); 5571 _humongous_set.bulk_remove(humongous_regions_removed); 5572 } 5573 5574 } 5575 5576 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 5577 assert(list != NULL, "list can't be null"); 5578 if (!list->is_empty()) { 5579 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5580 _hrm.insert_list_into_free_list(list); 5581 } 5582 } 5583 5584 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 5585 _allocator->decrease_used(bytes); 5586 } 5587 5588 class G1ParCleanupCTTask : public AbstractGangTask { 5589 G1SATBCardTableModRefBS* _ct_bs; 5590 G1CollectedHeap* _g1h; 5591 HeapRegion* volatile _su_head; 5592 public: 5593 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 5594 G1CollectedHeap* g1h) : 5595 AbstractGangTask("G1 Par Cleanup CT Task"), 5596 _ct_bs(ct_bs), _g1h(g1h) { } 5597 5598 void work(uint worker_id) { 5599 HeapRegion* r; 5600 while (r = _g1h->pop_dirty_cards_region()) { 5601 clear_cards(r); 5602 } 5603 } 5604 5605 void clear_cards(HeapRegion* r) { 5606 // Cards of the survivors should have already been dirtied. 5607 if (!r->is_survivor()) { 5608 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5609 } 5610 } 5611 }; 5612 5613 #ifndef PRODUCT 5614 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5615 G1CollectedHeap* _g1h; 5616 G1SATBCardTableModRefBS* _ct_bs; 5617 public: 5618 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 5619 : _g1h(g1h), _ct_bs(ct_bs) { } 5620 virtual bool doHeapRegion(HeapRegion* r) { 5621 if (r->is_survivor()) { 5622 _g1h->verify_dirty_region(r); 5623 } else { 5624 _g1h->verify_not_dirty_region(r); 5625 } 5626 return false; 5627 } 5628 }; 5629 5630 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5631 // All of the region should be clean. 5632 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5633 MemRegion mr(hr->bottom(), hr->end()); 5634 ct_bs->verify_not_dirty_region(mr); 5635 } 5636 5637 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5638 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5639 // dirty allocated blocks as they allocate them. The thread that 5640 // retires each region and replaces it with a new one will do a 5641 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5642 // not dirty that area (one less thing to have to do while holding 5643 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5644 // is dirty. 5645 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5646 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5647 if (hr->is_young()) { 5648 ct_bs->verify_g1_young_region(mr); 5649 } else { 5650 ct_bs->verify_dirty_region(mr); 5651 } 5652 } 5653 5654 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5655 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5656 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5657 verify_dirty_region(hr); 5658 } 5659 } 5660 5661 void G1CollectedHeap::verify_dirty_young_regions() { 5662 verify_dirty_young_list(_young_list->first_region()); 5663 } 5664 5665 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 5666 HeapWord* tams, HeapWord* end) { 5667 guarantee(tams <= end, 5668 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end)); 5669 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 5670 if (result < end) { 5671 gclog_or_tty->cr(); 5672 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT, 5673 bitmap_name, result); 5674 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT, 5675 bitmap_name, tams, end); 5676 return false; 5677 } 5678 return true; 5679 } 5680 5681 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 5682 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 5683 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 5684 5685 HeapWord* bottom = hr->bottom(); 5686 HeapWord* ptams = hr->prev_top_at_mark_start(); 5687 HeapWord* ntams = hr->next_top_at_mark_start(); 5688 HeapWord* end = hr->end(); 5689 5690 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 5691 5692 bool res_n = true; 5693 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 5694 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 5695 // if we happen to be in that state. 5696 if (mark_in_progress() || !_cmThread->in_progress()) { 5697 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 5698 } 5699 if (!res_p || !res_n) { 5700 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT, 5701 HR_FORMAT_PARAMS(hr)); 5702 gclog_or_tty->print_cr("#### Caller: %s", caller); 5703 return false; 5704 } 5705 return true; 5706 } 5707 5708 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 5709 if (!G1VerifyBitmaps) return; 5710 5711 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 5712 } 5713 5714 class G1VerifyBitmapClosure : public HeapRegionClosure { 5715 private: 5716 const char* _caller; 5717 G1CollectedHeap* _g1h; 5718 bool _failures; 5719 5720 public: 5721 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 5722 _caller(caller), _g1h(g1h), _failures(false) { } 5723 5724 bool failures() { return _failures; } 5725 5726 virtual bool doHeapRegion(HeapRegion* hr) { 5727 if (hr->is_continues_humongous()) return false; 5728 5729 bool result = _g1h->verify_bitmaps(_caller, hr); 5730 if (!result) { 5731 _failures = true; 5732 } 5733 return false; 5734 } 5735 }; 5736 5737 void G1CollectedHeap::check_bitmaps(const char* caller) { 5738 if (!G1VerifyBitmaps) return; 5739 5740 G1VerifyBitmapClosure cl(caller, this); 5741 heap_region_iterate(&cl); 5742 guarantee(!cl.failures(), "bitmap verification"); 5743 } 5744 5745 class G1CheckCSetFastTableClosure : public HeapRegionClosure { 5746 private: 5747 bool _failures; 5748 public: 5749 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { } 5750 5751 virtual bool doHeapRegion(HeapRegion* hr) { 5752 uint i = hr->hrm_index(); 5753 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i); 5754 if (hr->is_humongous()) { 5755 if (hr->in_collection_set()) { 5756 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i); 5757 _failures = true; 5758 return true; 5759 } 5760 if (cset_state.is_in_cset()) { 5761 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i); 5762 _failures = true; 5763 return true; 5764 } 5765 if (hr->is_continues_humongous() && cset_state.is_humongous()) { 5766 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i); 5767 _failures = true; 5768 return true; 5769 } 5770 } else { 5771 if (cset_state.is_humongous()) { 5772 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i); 5773 _failures = true; 5774 return true; 5775 } 5776 if (hr->in_collection_set() != cset_state.is_in_cset()) { 5777 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u", 5778 hr->in_collection_set(), cset_state.value(), i); 5779 _failures = true; 5780 return true; 5781 } 5782 if (cset_state.is_in_cset()) { 5783 if (hr->is_young() != (cset_state.is_young())) { 5784 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u", 5785 hr->is_young(), cset_state.value(), i); 5786 _failures = true; 5787 return true; 5788 } 5789 if (hr->is_old() != (cset_state.is_old())) { 5790 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u", 5791 hr->is_old(), cset_state.value(), i); 5792 _failures = true; 5793 return true; 5794 } 5795 } 5796 } 5797 return false; 5798 } 5799 5800 bool failures() const { return _failures; } 5801 }; 5802 5803 bool G1CollectedHeap::check_cset_fast_test() { 5804 G1CheckCSetFastTableClosure cl; 5805 _hrm.iterate(&cl); 5806 return !cl.failures(); 5807 } 5808 #endif // PRODUCT 5809 5810 void G1CollectedHeap::cleanUpCardTable() { 5811 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5812 double start = os::elapsedTime(); 5813 5814 { 5815 // Iterate over the dirty cards region list. 5816 G1ParCleanupCTTask cleanup_task(ct_bs, this); 5817 5818 set_par_threads(); 5819 workers()->run_task(&cleanup_task); 5820 set_par_threads(0); 5821 #ifndef PRODUCT 5822 if (G1VerifyCTCleanup || VerifyAfterGC) { 5823 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 5824 heap_region_iterate(&cleanup_verifier); 5825 } 5826 #endif 5827 } 5828 5829 double elapsed = os::elapsedTime() - start; 5830 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 5831 } 5832 5833 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 5834 size_t pre_used = 0; 5835 FreeRegionList local_free_list("Local List for CSet Freeing"); 5836 5837 double young_time_ms = 0.0; 5838 double non_young_time_ms = 0.0; 5839 5840 // Since the collection set is a superset of the the young list, 5841 // all we need to do to clear the young list is clear its 5842 // head and length, and unlink any young regions in the code below 5843 _young_list->clear(); 5844 5845 G1CollectorPolicy* policy = g1_policy(); 5846 5847 double start_sec = os::elapsedTime(); 5848 bool non_young = true; 5849 5850 HeapRegion* cur = cs_head; 5851 int age_bound = -1; 5852 size_t rs_lengths = 0; 5853 5854 while (cur != NULL) { 5855 assert(!is_on_master_free_list(cur), "sanity"); 5856 if (non_young) { 5857 if (cur->is_young()) { 5858 double end_sec = os::elapsedTime(); 5859 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5860 non_young_time_ms += elapsed_ms; 5861 5862 start_sec = os::elapsedTime(); 5863 non_young = false; 5864 } 5865 } else { 5866 if (!cur->is_young()) { 5867 double end_sec = os::elapsedTime(); 5868 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5869 young_time_ms += elapsed_ms; 5870 5871 start_sec = os::elapsedTime(); 5872 non_young = true; 5873 } 5874 } 5875 5876 rs_lengths += cur->rem_set()->occupied_locked(); 5877 5878 HeapRegion* next = cur->next_in_collection_set(); 5879 assert(cur->in_collection_set(), "bad CS"); 5880 cur->set_next_in_collection_set(NULL); 5881 clear_in_cset(cur); 5882 5883 if (cur->is_young()) { 5884 int index = cur->young_index_in_cset(); 5885 assert(index != -1, "invariant"); 5886 assert((uint) index < policy->young_cset_region_length(), "invariant"); 5887 size_t words_survived = _surviving_young_words[index]; 5888 cur->record_surv_words_in_group(words_survived); 5889 5890 // At this point the we have 'popped' cur from the collection set 5891 // (linked via next_in_collection_set()) but it is still in the 5892 // young list (linked via next_young_region()). Clear the 5893 // _next_young_region field. 5894 cur->set_next_young_region(NULL); 5895 } else { 5896 int index = cur->young_index_in_cset(); 5897 assert(index == -1, "invariant"); 5898 } 5899 5900 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 5901 (!cur->is_young() && cur->young_index_in_cset() == -1), 5902 "invariant" ); 5903 5904 if (!cur->evacuation_failed()) { 5905 MemRegion used_mr = cur->used_region(); 5906 5907 // And the region is empty. 5908 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 5909 pre_used += cur->used(); 5910 free_region(cur, &local_free_list, false /* par */, true /* locked */); 5911 } else { 5912 cur->uninstall_surv_rate_group(); 5913 if (cur->is_young()) { 5914 cur->set_young_index_in_cset(-1); 5915 } 5916 cur->set_evacuation_failed(false); 5917 // The region is now considered to be old. 5918 cur->set_old(); 5919 _old_set.add(cur); 5920 evacuation_info.increment_collectionset_used_after(cur->used()); 5921 } 5922 cur = next; 5923 } 5924 5925 evacuation_info.set_regions_freed(local_free_list.length()); 5926 policy->record_max_rs_lengths(rs_lengths); 5927 policy->cset_regions_freed(); 5928 5929 double end_sec = os::elapsedTime(); 5930 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5931 5932 if (non_young) { 5933 non_young_time_ms += elapsed_ms; 5934 } else { 5935 young_time_ms += elapsed_ms; 5936 } 5937 5938 prepend_to_freelist(&local_free_list); 5939 decrement_summary_bytes(pre_used); 5940 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 5941 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 5942 } 5943 5944 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 5945 private: 5946 FreeRegionList* _free_region_list; 5947 HeapRegionSet* _proxy_set; 5948 HeapRegionSetCount _humongous_regions_removed; 5949 size_t _freed_bytes; 5950 public: 5951 5952 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 5953 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 5954 } 5955 5956 virtual bool doHeapRegion(HeapRegion* r) { 5957 if (!r->is_starts_humongous()) { 5958 return false; 5959 } 5960 5961 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 5962 5963 oop obj = (oop)r->bottom(); 5964 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 5965 5966 // The following checks whether the humongous object is live are sufficient. 5967 // The main additional check (in addition to having a reference from the roots 5968 // or the young gen) is whether the humongous object has a remembered set entry. 5969 // 5970 // A humongous object cannot be live if there is no remembered set for it 5971 // because: 5972 // - there can be no references from within humongous starts regions referencing 5973 // the object because we never allocate other objects into them. 5974 // (I.e. there are no intra-region references that may be missed by the 5975 // remembered set) 5976 // - as soon there is a remembered set entry to the humongous starts region 5977 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 5978 // until the end of a concurrent mark. 5979 // 5980 // It is not required to check whether the object has been found dead by marking 5981 // or not, in fact it would prevent reclamation within a concurrent cycle, as 5982 // all objects allocated during that time are considered live. 5983 // SATB marking is even more conservative than the remembered set. 5984 // So if at this point in the collection there is no remembered set entry, 5985 // nobody has a reference to it. 5986 // At the start of collection we flush all refinement logs, and remembered sets 5987 // are completely up-to-date wrt to references to the humongous object. 5988 // 5989 // Other implementation considerations: 5990 // - never consider object arrays at this time because they would pose 5991 // considerable effort for cleaning up the the remembered sets. This is 5992 // required because stale remembered sets might reference locations that 5993 // are currently allocated into. 5994 uint region_idx = r->hrm_index(); 5995 if (g1h->humongous_is_live(region_idx) || 5996 g1h->humongous_region_is_always_live(region_idx)) { 5997 5998 if (G1TraceEagerReclaimHumongousObjects) { 5999 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", 6000 region_idx, 6001 obj->size()*HeapWordSize, 6002 r->bottom(), 6003 r->region_num(), 6004 r->rem_set()->occupied(), 6005 r->rem_set()->strong_code_roots_list_length(), 6006 next_bitmap->isMarked(r->bottom()), 6007 g1h->humongous_is_live(region_idx), 6008 obj->is_objArray() 6009 ); 6010 } 6011 6012 return false; 6013 } 6014 6015 guarantee(!obj->is_objArray(), 6016 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.", 6017 r->bottom())); 6018 6019 if (G1TraceEagerReclaimHumongousObjects) { 6020 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", 6021 region_idx, 6022 obj->size()*HeapWordSize, 6023 r->bottom(), 6024 r->region_num(), 6025 r->rem_set()->occupied(), 6026 r->rem_set()->strong_code_roots_list_length(), 6027 next_bitmap->isMarked(r->bottom()), 6028 g1h->humongous_is_live(region_idx), 6029 obj->is_objArray() 6030 ); 6031 } 6032 // Need to clear mark bit of the humongous object if already set. 6033 if (next_bitmap->isMarked(r->bottom())) { 6034 next_bitmap->clear(r->bottom()); 6035 } 6036 _freed_bytes += r->used(); 6037 r->set_containing_set(NULL); 6038 _humongous_regions_removed.increment(1u, r->capacity()); 6039 g1h->free_humongous_region(r, _free_region_list, false); 6040 6041 return false; 6042 } 6043 6044 HeapRegionSetCount& humongous_free_count() { 6045 return _humongous_regions_removed; 6046 } 6047 6048 size_t bytes_freed() const { 6049 return _freed_bytes; 6050 } 6051 6052 size_t humongous_reclaimed() const { 6053 return _humongous_regions_removed.length(); 6054 } 6055 }; 6056 6057 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 6058 assert_at_safepoint(true); 6059 6060 if (!G1EagerReclaimHumongousObjects || 6061 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) { 6062 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 6063 return; 6064 } 6065 6066 double start_time = os::elapsedTime(); 6067 6068 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 6069 6070 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 6071 heap_region_iterate(&cl); 6072 6073 HeapRegionSetCount empty_set; 6074 remove_from_old_sets(empty_set, cl.humongous_free_count()); 6075 6076 G1HRPrinter* hr_printer = _g1h->hr_printer(); 6077 if (hr_printer->is_active()) { 6078 FreeRegionListIterator iter(&local_cleanup_list); 6079 while (iter.more_available()) { 6080 HeapRegion* hr = iter.get_next(); 6081 hr_printer->cleanup(hr); 6082 } 6083 } 6084 6085 prepend_to_freelist(&local_cleanup_list); 6086 decrement_summary_bytes(cl.bytes_freed()); 6087 6088 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 6089 cl.humongous_reclaimed()); 6090 } 6091 6092 // This routine is similar to the above but does not record 6093 // any policy statistics or update free lists; we are abandoning 6094 // the current incremental collection set in preparation of a 6095 // full collection. After the full GC we will start to build up 6096 // the incremental collection set again. 6097 // This is only called when we're doing a full collection 6098 // and is immediately followed by the tearing down of the young list. 6099 6100 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6101 HeapRegion* cur = cs_head; 6102 6103 while (cur != NULL) { 6104 HeapRegion* next = cur->next_in_collection_set(); 6105 assert(cur->in_collection_set(), "bad CS"); 6106 cur->set_next_in_collection_set(NULL); 6107 clear_in_cset(cur); 6108 cur->set_young_index_in_cset(-1); 6109 cur = next; 6110 } 6111 } 6112 6113 void G1CollectedHeap::set_free_regions_coming() { 6114 if (G1ConcRegionFreeingVerbose) { 6115 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6116 "setting free regions coming"); 6117 } 6118 6119 assert(!free_regions_coming(), "pre-condition"); 6120 _free_regions_coming = true; 6121 } 6122 6123 void G1CollectedHeap::reset_free_regions_coming() { 6124 assert(free_regions_coming(), "pre-condition"); 6125 6126 { 6127 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6128 _free_regions_coming = false; 6129 SecondaryFreeList_lock->notify_all(); 6130 } 6131 6132 if (G1ConcRegionFreeingVerbose) { 6133 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6134 "reset free regions coming"); 6135 } 6136 } 6137 6138 void G1CollectedHeap::wait_while_free_regions_coming() { 6139 // Most of the time we won't have to wait, so let's do a quick test 6140 // first before we take the lock. 6141 if (!free_regions_coming()) { 6142 return; 6143 } 6144 6145 if (G1ConcRegionFreeingVerbose) { 6146 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6147 "waiting for free regions"); 6148 } 6149 6150 { 6151 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6152 while (free_regions_coming()) { 6153 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6154 } 6155 } 6156 6157 if (G1ConcRegionFreeingVerbose) { 6158 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6159 "done waiting for free regions"); 6160 } 6161 } 6162 6163 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6164 assert(heap_lock_held_for_gc(), 6165 "the heap lock should already be held by or for this thread"); 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 }