1 /* 2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/metadataOnStackMark.hpp" 27 #include "classfile/stringTable.hpp" 28 #include "code/codeCache.hpp" 29 #include "code/icBuffer.hpp" 30 #include "gc/g1/bufferingOopClosure.hpp" 31 #include "gc/g1/concurrentG1Refine.hpp" 32 #include "gc/g1/concurrentG1RefineThread.hpp" 33 #include "gc/g1/concurrentMarkThread.inline.hpp" 34 #include "gc/g1/g1Allocator.inline.hpp" 35 #include "gc/g1/g1CollectedHeap.inline.hpp" 36 #include "gc/g1/g1CollectorPolicy.hpp" 37 #include "gc/g1/g1CollectorState.hpp" 38 #include "gc/g1/g1ErgoVerbose.hpp" 39 #include "gc/g1/g1EvacFailure.hpp" 40 #include "gc/g1/g1GCPhaseTimes.hpp" 41 #include "gc/g1/g1Log.hpp" 42 #include "gc/g1/g1MarkSweep.hpp" 43 #include "gc/g1/g1OopClosures.inline.hpp" 44 #include "gc/g1/g1ParScanThreadState.inline.hpp" 45 #include "gc/g1/g1RegionToSpaceMapper.hpp" 46 #include "gc/g1/g1RemSet.inline.hpp" 47 #include "gc/g1/g1RootProcessor.hpp" 48 #include "gc/g1/g1StringDedup.hpp" 49 #include "gc/g1/g1YCTypes.hpp" 50 #include "gc/g1/heapRegion.inline.hpp" 51 #include "gc/g1/heapRegionRemSet.hpp" 52 #include "gc/g1/heapRegionSet.inline.hpp" 53 #include "gc/g1/suspendibleThreadSet.hpp" 54 #include "gc/g1/vm_operations_g1.hpp" 55 #include "gc/shared/gcHeapSummary.hpp" 56 #include "gc/shared/gcLocker.inline.hpp" 57 #include "gc/shared/gcTimer.hpp" 58 #include "gc/shared/gcTrace.hpp" 59 #include "gc/shared/gcTraceTime.hpp" 60 #include "gc/shared/generationSpec.hpp" 61 #include "gc/shared/isGCActiveMark.hpp" 62 #include "gc/shared/referenceProcessor.hpp" 63 #include "gc/shared/taskqueue.inline.hpp" 64 #include "memory/allocation.hpp" 65 #include "memory/iterator.hpp" 66 #include "oops/oop.inline.hpp" 67 #include "runtime/atomic.inline.hpp" 68 #include "runtime/init.hpp" 69 #include "runtime/orderAccess.inline.hpp" 70 #include "runtime/vmThread.hpp" 71 #include "utilities/globalDefinitions.hpp" 72 #include "utilities/stack.inline.hpp" 73 74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 75 76 // INVARIANTS/NOTES 77 // 78 // All allocation activity covered by the G1CollectedHeap interface is 79 // serialized by acquiring the HeapLock. This happens in mem_allocate 80 // and allocate_new_tlab, which are the "entry" points to the 81 // allocation code from the rest of the JVM. (Note that this does not 82 // apply to TLAB allocation, which is not part of this interface: it 83 // is done by clients of this interface.) 84 85 // Local to this file. 86 87 class RefineCardTableEntryClosure: public CardTableEntryClosure { 88 bool _concurrent; 89 public: 90 RefineCardTableEntryClosure() : _concurrent(true) { } 91 92 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 93 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 94 // This path is executed by the concurrent refine or mutator threads, 95 // concurrently, and so we do not care if card_ptr contains references 96 // that point into the collection set. 97 assert(!oops_into_cset, "should be"); 98 99 if (_concurrent && SuspendibleThreadSet::should_yield()) { 100 // Caller will actually yield. 101 return false; 102 } 103 // Otherwise, we finished successfully; return true. 104 return true; 105 } 106 107 void set_concurrent(bool b) { _concurrent = b; } 108 }; 109 110 111 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 112 private: 113 size_t _num_processed; 114 115 public: 116 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { } 117 118 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 119 *card_ptr = CardTableModRefBS::dirty_card_val(); 120 _num_processed++; 121 return true; 122 } 123 124 size_t num_processed() const { return _num_processed; } 125 }; 126 127 YoungList::YoungList(G1CollectedHeap* g1h) : 128 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 129 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 130 guarantee(check_list_empty(false), "just making sure..."); 131 } 132 133 void YoungList::push_region(HeapRegion *hr) { 134 assert(!hr->is_young(), "should not already be young"); 135 assert(hr->get_next_young_region() == NULL, "cause it should!"); 136 137 hr->set_next_young_region(_head); 138 _head = hr; 139 140 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 141 ++_length; 142 } 143 144 void YoungList::add_survivor_region(HeapRegion* hr) { 145 assert(hr->is_survivor(), "should be flagged as survivor region"); 146 assert(hr->get_next_young_region() == NULL, "cause it should!"); 147 148 hr->set_next_young_region(_survivor_head); 149 if (_survivor_head == NULL) { 150 _survivor_tail = hr; 151 } 152 _survivor_head = hr; 153 ++_survivor_length; 154 } 155 156 void YoungList::empty_list(HeapRegion* list) { 157 while (list != NULL) { 158 HeapRegion* next = list->get_next_young_region(); 159 list->set_next_young_region(NULL); 160 list->uninstall_surv_rate_group(); 161 // This is called before a Full GC and all the non-empty / 162 // non-humongous regions at the end of the Full GC will end up as 163 // old anyway. 164 list->set_old(); 165 list = next; 166 } 167 } 168 169 void YoungList::empty_list() { 170 assert(check_list_well_formed(), "young list should be well formed"); 171 172 empty_list(_head); 173 _head = NULL; 174 _length = 0; 175 176 empty_list(_survivor_head); 177 _survivor_head = NULL; 178 _survivor_tail = NULL; 179 _survivor_length = 0; 180 181 _last_sampled_rs_lengths = 0; 182 183 assert(check_list_empty(false), "just making sure..."); 184 } 185 186 bool YoungList::check_list_well_formed() { 187 bool ret = true; 188 189 uint length = 0; 190 HeapRegion* curr = _head; 191 HeapRegion* last = NULL; 192 while (curr != NULL) { 193 if (!curr->is_young()) { 194 gclog_or_tty->print_cr("### YOUNG REGION " PTR_FORMAT "-" PTR_FORMAT " " 195 "incorrectly tagged (y: %d, surv: %d)", 196 p2i(curr->bottom()), p2i(curr->end()), 197 curr->is_young(), curr->is_survivor()); 198 ret = false; 199 } 200 ++length; 201 last = curr; 202 curr = curr->get_next_young_region(); 203 } 204 ret = ret && (length == _length); 205 206 if (!ret) { 207 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 208 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 209 length, _length); 210 } 211 212 return ret; 213 } 214 215 bool YoungList::check_list_empty(bool check_sample) { 216 bool ret = true; 217 218 if (_length != 0) { 219 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 220 _length); 221 ret = false; 222 } 223 if (check_sample && _last_sampled_rs_lengths != 0) { 224 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 225 ret = false; 226 } 227 if (_head != NULL) { 228 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 229 ret = false; 230 } 231 if (!ret) { 232 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 233 } 234 235 return ret; 236 } 237 238 void 239 YoungList::rs_length_sampling_init() { 240 _sampled_rs_lengths = 0; 241 _curr = _head; 242 } 243 244 bool 245 YoungList::rs_length_sampling_more() { 246 return _curr != NULL; 247 } 248 249 void 250 YoungList::rs_length_sampling_next() { 251 assert( _curr != NULL, "invariant" ); 252 size_t rs_length = _curr->rem_set()->occupied(); 253 254 _sampled_rs_lengths += rs_length; 255 256 // The current region may not yet have been added to the 257 // incremental collection set (it gets added when it is 258 // retired as the current allocation region). 259 if (_curr->in_collection_set()) { 260 // Update the collection set policy information for this region 261 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 262 } 263 264 _curr = _curr->get_next_young_region(); 265 if (_curr == NULL) { 266 _last_sampled_rs_lengths = _sampled_rs_lengths; 267 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 268 } 269 } 270 271 void 272 YoungList::reset_auxilary_lists() { 273 guarantee( is_empty(), "young list should be empty" ); 274 assert(check_list_well_formed(), "young list should be well formed"); 275 276 // Add survivor regions to SurvRateGroup. 277 _g1h->g1_policy()->note_start_adding_survivor_regions(); 278 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 279 280 int young_index_in_cset = 0; 281 for (HeapRegion* curr = _survivor_head; 282 curr != NULL; 283 curr = curr->get_next_young_region()) { 284 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 285 286 // The region is a non-empty survivor so let's add it to 287 // the incremental collection set for the next evacuation 288 // pause. 289 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 290 young_index_in_cset += 1; 291 } 292 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 293 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 294 295 _head = _survivor_head; 296 _length = _survivor_length; 297 if (_survivor_head != NULL) { 298 assert(_survivor_tail != NULL, "cause it shouldn't be"); 299 assert(_survivor_length > 0, "invariant"); 300 _survivor_tail->set_next_young_region(NULL); 301 } 302 303 // Don't clear the survivor list handles until the start of 304 // the next evacuation pause - we need it in order to re-tag 305 // the survivor regions from this evacuation pause as 'young' 306 // at the start of the next. 307 308 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 309 310 assert(check_list_well_formed(), "young list should be well formed"); 311 } 312 313 void YoungList::print() { 314 HeapRegion* lists[] = {_head, _survivor_head}; 315 const char* names[] = {"YOUNG", "SURVIVOR"}; 316 317 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) { 318 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 319 HeapRegion *curr = lists[list]; 320 if (curr == NULL) 321 gclog_or_tty->print_cr(" empty"); 322 while (curr != NULL) { 323 gclog_or_tty->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT ", N: " PTR_FORMAT ", age: %4d", 324 HR_FORMAT_PARAMS(curr), 325 p2i(curr->prev_top_at_mark_start()), 326 p2i(curr->next_top_at_mark_start()), 327 curr->age_in_surv_rate_group_cond()); 328 curr = curr->get_next_young_region(); 329 } 330 } 331 332 gclog_or_tty->cr(); 333 } 334 335 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 336 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 337 } 338 339 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 340 // The from card cache is not the memory that is actually committed. So we cannot 341 // take advantage of the zero_filled parameter. 342 reset_from_card_cache(start_idx, num_regions); 343 } 344 345 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 346 { 347 // Claim the right to put the region on the dirty cards region list 348 // by installing a self pointer. 349 HeapRegion* next = hr->get_next_dirty_cards_region(); 350 if (next == NULL) { 351 HeapRegion* res = (HeapRegion*) 352 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 353 NULL); 354 if (res == NULL) { 355 HeapRegion* head; 356 do { 357 // Put the region to the dirty cards region list. 358 head = _dirty_cards_region_list; 359 next = (HeapRegion*) 360 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 361 if (next == head) { 362 assert(hr->get_next_dirty_cards_region() == hr, 363 "hr->get_next_dirty_cards_region() != hr"); 364 if (next == NULL) { 365 // The last region in the list points to itself. 366 hr->set_next_dirty_cards_region(hr); 367 } else { 368 hr->set_next_dirty_cards_region(next); 369 } 370 } 371 } while (next != head); 372 } 373 } 374 } 375 376 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 377 { 378 HeapRegion* head; 379 HeapRegion* hr; 380 do { 381 head = _dirty_cards_region_list; 382 if (head == NULL) { 383 return NULL; 384 } 385 HeapRegion* new_head = head->get_next_dirty_cards_region(); 386 if (head == new_head) { 387 // The last region. 388 new_head = NULL; 389 } 390 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 391 head); 392 } while (hr != head); 393 assert(hr != NULL, "invariant"); 394 hr->set_next_dirty_cards_region(NULL); 395 return hr; 396 } 397 398 // Returns true if the reference points to an object that 399 // can move in an incremental collection. 400 bool G1CollectedHeap::is_scavengable(const void* p) { 401 HeapRegion* hr = heap_region_containing(p); 402 return !hr->is_pinned(); 403 } 404 405 // Private methods. 406 407 HeapRegion* 408 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 409 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 410 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 411 if (!_secondary_free_list.is_empty()) { 412 if (G1ConcRegionFreeingVerbose) { 413 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 414 "secondary_free_list has %u entries", 415 _secondary_free_list.length()); 416 } 417 // It looks as if there are free regions available on the 418 // secondary_free_list. Let's move them to the free_list and try 419 // again to allocate from it. 420 append_secondary_free_list(); 421 422 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 423 "empty we should have moved at least one entry to the free_list"); 424 HeapRegion* res = _hrm.allocate_free_region(is_old); 425 if (G1ConcRegionFreeingVerbose) { 426 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 427 "allocated " HR_FORMAT " from secondary_free_list", 428 HR_FORMAT_PARAMS(res)); 429 } 430 return res; 431 } 432 433 // Wait here until we get notified either when (a) there are no 434 // more free regions coming or (b) some regions have been moved on 435 // the secondary_free_list. 436 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 437 } 438 439 if (G1ConcRegionFreeingVerbose) { 440 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 441 "could not allocate from secondary_free_list"); 442 } 443 return NULL; 444 } 445 446 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 447 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 448 "the only time we use this to allocate a humongous region is " 449 "when we are allocating a single humongous region"); 450 451 HeapRegion* res; 452 if (G1StressConcRegionFreeing) { 453 if (!_secondary_free_list.is_empty()) { 454 if (G1ConcRegionFreeingVerbose) { 455 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 456 "forced to look at the secondary_free_list"); 457 } 458 res = new_region_try_secondary_free_list(is_old); 459 if (res != NULL) { 460 return res; 461 } 462 } 463 } 464 465 res = _hrm.allocate_free_region(is_old); 466 467 if (res == NULL) { 468 if (G1ConcRegionFreeingVerbose) { 469 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 470 "res == NULL, trying the secondary_free_list"); 471 } 472 res = new_region_try_secondary_free_list(is_old); 473 } 474 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 475 // Currently, only attempts to allocate GC alloc regions set 476 // do_expand to true. So, we should only reach here during a 477 // safepoint. If this assumption changes we might have to 478 // reconsider the use of _expand_heap_after_alloc_failure. 479 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 480 481 ergo_verbose1(ErgoHeapSizing, 482 "attempt heap expansion", 483 ergo_format_reason("region allocation request failed") 484 ergo_format_byte("allocation request"), 485 word_size * HeapWordSize); 486 if (expand(word_size * HeapWordSize)) { 487 // Given that expand() succeeded in expanding the heap, and we 488 // always expand the heap by an amount aligned to the heap 489 // region size, the free list should in theory not be empty. 490 // In either case allocate_free_region() will check for NULL. 491 res = _hrm.allocate_free_region(is_old); 492 } else { 493 _expand_heap_after_alloc_failure = false; 494 } 495 } 496 return res; 497 } 498 499 HeapWord* 500 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 501 uint num_regions, 502 size_t word_size, 503 AllocationContext_t context) { 504 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 505 assert(is_humongous(word_size), "word_size should be humongous"); 506 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 507 508 // Index of last region in the series + 1. 509 uint last = first + num_regions; 510 511 // We need to initialize the region(s) we just discovered. This is 512 // a bit tricky given that it can happen concurrently with 513 // refinement threads refining cards on these regions and 514 // potentially wanting to refine the BOT as they are scanning 515 // those cards (this can happen shortly after a cleanup; see CR 516 // 6991377). So we have to set up the region(s) carefully and in 517 // a specific order. 518 519 // The word size sum of all the regions we will allocate. 520 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 521 assert(word_size <= word_size_sum, "sanity"); 522 523 // This will be the "starts humongous" region. 524 HeapRegion* first_hr = region_at(first); 525 // The header of the new object will be placed at the bottom of 526 // the first region. 527 HeapWord* new_obj = first_hr->bottom(); 528 // This will be the new end of the first region in the series that 529 // should also match the end of the last region in the series. 530 HeapWord* new_end = new_obj + word_size_sum; 531 // This will be the new top of the first region that will reflect 532 // this allocation. 533 HeapWord* new_top = new_obj + word_size; 534 535 // First, we need to zero the header of the space that we will be 536 // allocating. When we update top further down, some refinement 537 // threads might try to scan the region. By zeroing the header we 538 // ensure that any thread that will try to scan the region will 539 // come across the zero klass word and bail out. 540 // 541 // NOTE: It would not have been correct to have used 542 // CollectedHeap::fill_with_object() and make the space look like 543 // an int array. The thread that is doing the allocation will 544 // later update the object header to a potentially different array 545 // type and, for a very short period of time, the klass and length 546 // fields will be inconsistent. This could cause a refinement 547 // thread to calculate the object size incorrectly. 548 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 549 550 // We will set up the first region as "starts humongous". This 551 // will also update the BOT covering all the regions to reflect 552 // that there is a single object that starts at the bottom of the 553 // first region. 554 first_hr->set_starts_humongous(new_top, new_end); 555 first_hr->set_allocation_context(context); 556 // Then, if there are any, we will set up the "continues 557 // humongous" regions. 558 HeapRegion* hr = NULL; 559 for (uint i = first + 1; i < last; ++i) { 560 hr = region_at(i); 561 hr->set_continues_humongous(first_hr); 562 hr->set_allocation_context(context); 563 } 564 // If we have "continues humongous" regions (hr != NULL), then the 565 // end of the last one should match new_end. 566 assert(hr == NULL || hr->end() == new_end, "sanity"); 567 568 // Up to this point no concurrent thread would have been able to 569 // do any scanning on any region in this series. All the top 570 // fields still point to bottom, so the intersection between 571 // [bottom,top] and [card_start,card_end] will be empty. Before we 572 // update the top fields, we'll do a storestore to make sure that 573 // no thread sees the update to top before the zeroing of the 574 // object header and the BOT initialization. 575 OrderAccess::storestore(); 576 577 // Now that the BOT and the object header have been initialized, 578 // we can update top of the "starts humongous" region. 579 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 580 "new_top should be in this region"); 581 first_hr->set_top(new_top); 582 if (_hr_printer.is_active()) { 583 HeapWord* bottom = first_hr->bottom(); 584 HeapWord* end = first_hr->orig_end(); 585 if ((first + 1) == last) { 586 // the series has a single humongous region 587 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 588 } else { 589 // the series has more than one humongous regions 590 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 591 } 592 } 593 594 // Now, we will update the top fields of the "continues humongous" 595 // regions. The reason we need to do this is that, otherwise, 596 // these regions would look empty and this will confuse parts of 597 // G1. For example, the code that looks for a consecutive number 598 // of empty regions will consider them empty and try to 599 // re-allocate them. We can extend is_empty() to also include 600 // !is_continues_humongous(), but it is easier to just update the top 601 // fields here. The way we set top for all regions (i.e., top == 602 // end for all regions but the last one, top == new_top for the 603 // last one) is actually used when we will free up the humongous 604 // region in free_humongous_region(). 605 hr = NULL; 606 for (uint i = first + 1; i < last; ++i) { 607 hr = region_at(i); 608 if ((i + 1) == last) { 609 // last continues humongous region 610 assert(hr->bottom() < new_top && new_top <= hr->end(), 611 "new_top should fall on this region"); 612 hr->set_top(new_top); 613 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 614 } else { 615 // not last one 616 assert(new_top > hr->end(), "new_top should be above this region"); 617 hr->set_top(hr->end()); 618 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 619 } 620 } 621 // If we have continues humongous regions (hr != NULL), then the 622 // end of the last one should match new_end and its top should 623 // match new_top. 624 assert(hr == NULL || 625 (hr->end() == new_end && hr->top() == new_top), "sanity"); 626 check_bitmaps("Humongous Region Allocation", first_hr); 627 628 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 629 increase_used(first_hr->used()); 630 _humongous_set.add(first_hr); 631 632 return new_obj; 633 } 634 635 // If could fit into free regions w/o expansion, try. 636 // Otherwise, if can expand, do so. 637 // Otherwise, if using ex regions might help, try with ex given back. 638 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 639 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 640 641 verify_region_sets_optional(); 642 643 uint first = G1_NO_HRM_INDEX; 644 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords); 645 646 if (obj_regions == 1) { 647 // Only one region to allocate, try to use a fast path by directly allocating 648 // from the free lists. Do not try to expand here, we will potentially do that 649 // later. 650 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 651 if (hr != NULL) { 652 first = hr->hrm_index(); 653 } 654 } else { 655 // We can't allocate humongous regions spanning more than one region while 656 // cleanupComplete() is running, since some of the regions we find to be 657 // empty might not yet be added to the free list. It is not straightforward 658 // to know in which list they are on so that we can remove them. We only 659 // need to do this if we need to allocate more than one region to satisfy the 660 // current humongous allocation request. If we are only allocating one region 661 // we use the one-region region allocation code (see above), that already 662 // potentially waits for regions from the secondary free list. 663 wait_while_free_regions_coming(); 664 append_secondary_free_list_if_not_empty_with_lock(); 665 666 // Policy: Try only empty regions (i.e. already committed first). Maybe we 667 // are lucky enough to find some. 668 first = _hrm.find_contiguous_only_empty(obj_regions); 669 if (first != G1_NO_HRM_INDEX) { 670 _hrm.allocate_free_regions_starting_at(first, obj_regions); 671 } 672 } 673 674 if (first == G1_NO_HRM_INDEX) { 675 // Policy: We could not find enough regions for the humongous object in the 676 // free list. Look through the heap to find a mix of free and uncommitted regions. 677 // If so, try expansion. 678 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 679 if (first != G1_NO_HRM_INDEX) { 680 // We found something. Make sure these regions are committed, i.e. expand 681 // the heap. Alternatively we could do a defragmentation GC. 682 ergo_verbose1(ErgoHeapSizing, 683 "attempt heap expansion", 684 ergo_format_reason("humongous allocation request failed") 685 ergo_format_byte("allocation request"), 686 word_size * HeapWordSize); 687 688 _hrm.expand_at(first, obj_regions); 689 g1_policy()->record_new_heap_size(num_regions()); 690 691 #ifdef ASSERT 692 for (uint i = first; i < first + obj_regions; ++i) { 693 HeapRegion* hr = region_at(i); 694 assert(hr->is_free(), "sanity"); 695 assert(hr->is_empty(), "sanity"); 696 assert(is_on_master_free_list(hr), "sanity"); 697 } 698 #endif 699 _hrm.allocate_free_regions_starting_at(first, obj_regions); 700 } else { 701 // Policy: Potentially trigger a defragmentation GC. 702 } 703 } 704 705 HeapWord* result = NULL; 706 if (first != G1_NO_HRM_INDEX) { 707 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 708 word_size, context); 709 assert(result != NULL, "it should always return a valid result"); 710 711 // A successful humongous object allocation changes the used space 712 // information of the old generation so we need to recalculate the 713 // sizes and update the jstat counters here. 714 g1mm()->update_sizes(); 715 } 716 717 verify_region_sets_optional(); 718 719 return result; 720 } 721 722 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 723 assert_heap_not_locked_and_not_at_safepoint(); 724 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 725 726 uint dummy_gc_count_before; 727 uint dummy_gclocker_retry_count = 0; 728 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 729 } 730 731 HeapWord* 732 G1CollectedHeap::mem_allocate(size_t word_size, 733 bool* gc_overhead_limit_was_exceeded) { 734 assert_heap_not_locked_and_not_at_safepoint(); 735 736 // Loop until the allocation is satisfied, or unsatisfied after GC. 737 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 738 uint gc_count_before; 739 740 HeapWord* result = NULL; 741 if (!is_humongous(word_size)) { 742 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 743 } else { 744 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 745 } 746 if (result != NULL) { 747 return result; 748 } 749 750 // Create the garbage collection operation... 751 VM_G1CollectForAllocation op(gc_count_before, word_size); 752 op.set_allocation_context(AllocationContext::current()); 753 754 // ...and get the VM thread to execute it. 755 VMThread::execute(&op); 756 757 if (op.prologue_succeeded() && op.pause_succeeded()) { 758 // If the operation was successful we'll return the result even 759 // if it is NULL. If the allocation attempt failed immediately 760 // after a Full GC, it's unlikely we'll be able to allocate now. 761 HeapWord* result = op.result(); 762 if (result != NULL && !is_humongous(word_size)) { 763 // Allocations that take place on VM operations do not do any 764 // card dirtying and we have to do it here. We only have to do 765 // this for non-humongous allocations, though. 766 dirty_young_block(result, word_size); 767 } 768 return result; 769 } else { 770 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 771 return NULL; 772 } 773 assert(op.result() == NULL, 774 "the result should be NULL if the VM op did not succeed"); 775 } 776 777 // Give a warning if we seem to be looping forever. 778 if ((QueuedAllocationWarningCount > 0) && 779 (try_count % QueuedAllocationWarningCount == 0)) { 780 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 781 } 782 } 783 784 ShouldNotReachHere(); 785 return NULL; 786 } 787 788 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 789 AllocationContext_t context, 790 uint* gc_count_before_ret, 791 uint* gclocker_retry_count_ret) { 792 // Make sure you read the note in attempt_allocation_humongous(). 793 794 assert_heap_not_locked_and_not_at_safepoint(); 795 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 796 "be called for humongous allocation requests"); 797 798 // We should only get here after the first-level allocation attempt 799 // (attempt_allocation()) failed to allocate. 800 801 // We will loop until a) we manage to successfully perform the 802 // allocation or b) we successfully schedule a collection which 803 // fails to perform the allocation. b) is the only case when we'll 804 // return NULL. 805 HeapWord* result = NULL; 806 for (int try_count = 1; /* we'll return */; try_count += 1) { 807 bool should_try_gc; 808 uint gc_count_before; 809 810 { 811 MutexLockerEx x(Heap_lock); 812 result = _allocator->attempt_allocation_locked(word_size, context); 813 if (result != NULL) { 814 return result; 815 } 816 817 if (GC_locker::is_active_and_needs_gc()) { 818 if (g1_policy()->can_expand_young_list()) { 819 // No need for an ergo verbose message here, 820 // can_expand_young_list() does this when it returns true. 821 result = _allocator->attempt_allocation_force(word_size, context); 822 if (result != NULL) { 823 return result; 824 } 825 } 826 should_try_gc = false; 827 } else { 828 // The GCLocker may not be active but the GCLocker initiated 829 // GC may not yet have been performed (GCLocker::needs_gc() 830 // returns true). In this case we do not try this GC and 831 // wait until the GCLocker initiated GC is performed, and 832 // then retry the allocation. 833 if (GC_locker::needs_gc()) { 834 should_try_gc = false; 835 } else { 836 // Read the GC count while still holding the Heap_lock. 837 gc_count_before = total_collections(); 838 should_try_gc = true; 839 } 840 } 841 } 842 843 if (should_try_gc) { 844 bool succeeded; 845 result = do_collection_pause(word_size, gc_count_before, &succeeded, 846 GCCause::_g1_inc_collection_pause); 847 if (result != NULL) { 848 assert(succeeded, "only way to get back a non-NULL result"); 849 return result; 850 } 851 852 if (succeeded) { 853 // If we get here we successfully scheduled a collection which 854 // failed to allocate. No point in trying to allocate 855 // further. We'll just return NULL. 856 MutexLockerEx x(Heap_lock); 857 *gc_count_before_ret = total_collections(); 858 return NULL; 859 } 860 } else { 861 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 862 MutexLockerEx x(Heap_lock); 863 *gc_count_before_ret = total_collections(); 864 return NULL; 865 } 866 // The GCLocker is either active or the GCLocker initiated 867 // GC has not yet been performed. Stall until it is and 868 // then retry the allocation. 869 GC_locker::stall_until_clear(); 870 (*gclocker_retry_count_ret) += 1; 871 } 872 873 // We can reach here if we were unsuccessful in scheduling a 874 // collection (because another thread beat us to it) or if we were 875 // stalled due to the GC locker. In either can we should retry the 876 // allocation attempt in case another thread successfully 877 // performed a collection and reclaimed enough space. We do the 878 // first attempt (without holding the Heap_lock) here and the 879 // follow-on attempt will be at the start of the next loop 880 // iteration (after taking the Heap_lock). 881 result = _allocator->attempt_allocation(word_size, context); 882 if (result != NULL) { 883 return result; 884 } 885 886 // Give a warning if we seem to be looping forever. 887 if ((QueuedAllocationWarningCount > 0) && 888 (try_count % QueuedAllocationWarningCount == 0)) { 889 warning("G1CollectedHeap::attempt_allocation_slow() " 890 "retries %d times", try_count); 891 } 892 } 893 894 ShouldNotReachHere(); 895 return NULL; 896 } 897 898 void G1CollectedHeap::begin_archive_alloc_range() { 899 assert_at_safepoint(true /* should_be_vm_thread */); 900 if (_archive_allocator == NULL) { 901 _archive_allocator = G1ArchiveAllocator::create_allocator(this); 902 } 903 } 904 905 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 906 // Allocations in archive regions cannot be of a size that would be considered 907 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 908 // may be different at archive-restore time. 909 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 910 } 911 912 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 913 assert_at_safepoint(true /* should_be_vm_thread */); 914 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 915 if (is_archive_alloc_too_large(word_size)) { 916 return NULL; 917 } 918 return _archive_allocator->archive_mem_allocate(word_size); 919 } 920 921 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 922 size_t end_alignment_in_bytes) { 923 assert_at_safepoint(true /* should_be_vm_thread */); 924 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 925 926 // Call complete_archive to do the real work, filling in the MemRegion 927 // array with the archive regions. 928 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 929 delete _archive_allocator; 930 _archive_allocator = NULL; 931 } 932 933 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 934 assert(ranges != NULL, "MemRegion array NULL"); 935 assert(count != 0, "No MemRegions provided"); 936 MemRegion reserved = _hrm.reserved(); 937 for (size_t i = 0; i < count; i++) { 938 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 939 return false; 940 } 941 } 942 return true; 943 } 944 945 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) { 946 assert(!is_init_completed(), "Expect to be called at JVM init time"); 947 assert(ranges != NULL, "MemRegion array NULL"); 948 assert(count != 0, "No MemRegions provided"); 949 MutexLockerEx x(Heap_lock); 950 951 MemRegion reserved = _hrm.reserved(); 952 HeapWord* prev_last_addr = NULL; 953 HeapRegion* prev_last_region = NULL; 954 955 // Temporarily disable pretouching of heap pages. This interface is used 956 // when mmap'ing archived heap data in, so pre-touching is wasted. 957 FlagSetting fs(AlwaysPreTouch, false); 958 959 // Enable archive object checking in G1MarkSweep. We have to let it know 960 // about each archive range, so that objects in those ranges aren't marked. 961 G1MarkSweep::enable_archive_object_check(); 962 963 // For each specified MemRegion range, allocate the corresponding G1 964 // regions and mark them as archive regions. We expect the ranges in 965 // ascending starting address order, without overlap. 966 for (size_t i = 0; i < count; i++) { 967 MemRegion curr_range = ranges[i]; 968 HeapWord* start_address = curr_range.start(); 969 size_t word_size = curr_range.word_size(); 970 HeapWord* last_address = curr_range.last(); 971 size_t commits = 0; 972 973 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 974 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 975 p2i(start_address), p2i(last_address))); 976 guarantee(start_address > prev_last_addr, 977 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 978 p2i(start_address), p2i(prev_last_addr))); 979 prev_last_addr = last_address; 980 981 // Check for ranges that start in the same G1 region in which the previous 982 // range ended, and adjust the start address so we don't try to allocate 983 // the same region again. If the current range is entirely within that 984 // region, skip it, just adjusting the recorded top. 985 HeapRegion* start_region = _hrm.addr_to_region(start_address); 986 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 987 start_address = start_region->end(); 988 if (start_address > last_address) { 989 increase_used(word_size * HeapWordSize); 990 start_region->set_top(last_address + 1); 991 continue; 992 } 993 start_region->set_top(start_address); 994 curr_range = MemRegion(start_address, last_address + 1); 995 start_region = _hrm.addr_to_region(start_address); 996 } 997 998 // Perform the actual region allocation, exiting if it fails. 999 // Then note how much new space we have allocated. 1000 if (!_hrm.allocate_containing_regions(curr_range, &commits)) { 1001 return false; 1002 } 1003 increase_used(word_size * HeapWordSize); 1004 if (commits != 0) { 1005 ergo_verbose1(ErgoHeapSizing, 1006 "attempt heap expansion", 1007 ergo_format_reason("allocate archive regions") 1008 ergo_format_byte("total size"), 1009 HeapRegion::GrainWords * HeapWordSize * commits); 1010 } 1011 1012 // Mark each G1 region touched by the range as archive, add it to the old set, 1013 // and set the allocation context and top. 1014 HeapRegion* curr_region = _hrm.addr_to_region(start_address); 1015 HeapRegion* last_region = _hrm.addr_to_region(last_address); 1016 prev_last_region = last_region; 1017 1018 while (curr_region != NULL) { 1019 assert(curr_region->is_empty() && !curr_region->is_pinned(), 1020 err_msg("Region already in use (index %u)", curr_region->hrm_index())); 1021 _hr_printer.alloc(curr_region, G1HRPrinter::Archive); 1022 curr_region->set_allocation_context(AllocationContext::system()); 1023 curr_region->set_archive(); 1024 _old_set.add(curr_region); 1025 if (curr_region != last_region) { 1026 curr_region->set_top(curr_region->end()); 1027 curr_region = _hrm.next_region_in_heap(curr_region); 1028 } else { 1029 curr_region->set_top(last_address + 1); 1030 curr_region = NULL; 1031 } 1032 } 1033 1034 // Notify mark-sweep of the archive range. 1035 G1MarkSweep::set_range_archive(curr_range, true); 1036 } 1037 return true; 1038 } 1039 1040 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 1041 assert(!is_init_completed(), "Expect to be called at JVM init time"); 1042 assert(ranges != NULL, "MemRegion array NULL"); 1043 assert(count != 0, "No MemRegions provided"); 1044 MemRegion reserved = _hrm.reserved(); 1045 HeapWord *prev_last_addr = NULL; 1046 HeapRegion* prev_last_region = NULL; 1047 1048 // For each MemRegion, create filler objects, if needed, in the G1 regions 1049 // that contain the address range. The address range actually within the 1050 // MemRegion will not be modified. That is assumed to have been initialized 1051 // elsewhere, probably via an mmap of archived heap data. 1052 MutexLockerEx x(Heap_lock); 1053 for (size_t i = 0; i < count; i++) { 1054 HeapWord* start_address = ranges[i].start(); 1055 HeapWord* last_address = ranges[i].last(); 1056 1057 assert(reserved.contains(start_address) && reserved.contains(last_address), 1058 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 1059 p2i(start_address), p2i(last_address))); 1060 assert(start_address > prev_last_addr, 1061 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 1062 p2i(start_address), p2i(prev_last_addr))); 1063 1064 HeapRegion* start_region = _hrm.addr_to_region(start_address); 1065 HeapRegion* last_region = _hrm.addr_to_region(last_address); 1066 HeapWord* bottom_address = start_region->bottom(); 1067 1068 // Check for a range beginning in the same region in which the 1069 // previous one ended. 1070 if (start_region == prev_last_region) { 1071 bottom_address = prev_last_addr + 1; 1072 } 1073 1074 // Verify that the regions were all marked as archive regions by 1075 // alloc_archive_regions. 1076 HeapRegion* curr_region = start_region; 1077 while (curr_region != NULL) { 1078 guarantee(curr_region->is_archive(), 1079 err_msg("Expected archive region at index %u", curr_region->hrm_index())); 1080 if (curr_region != last_region) { 1081 curr_region = _hrm.next_region_in_heap(curr_region); 1082 } else { 1083 curr_region = NULL; 1084 } 1085 } 1086 1087 prev_last_addr = last_address; 1088 prev_last_region = last_region; 1089 1090 // Fill the memory below the allocated range with dummy object(s), 1091 // if the region bottom does not match the range start, or if the previous 1092 // range ended within the same G1 region, and there is a gap. 1093 if (start_address != bottom_address) { 1094 size_t fill_size = pointer_delta(start_address, bottom_address); 1095 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 1096 increase_used(fill_size * HeapWordSize); 1097 } 1098 } 1099 } 1100 1101 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size, 1102 uint* gc_count_before_ret, 1103 uint* gclocker_retry_count_ret) { 1104 assert_heap_not_locked_and_not_at_safepoint(); 1105 assert(!is_humongous(word_size), "attempt_allocation() should not " 1106 "be called for humongous allocation requests"); 1107 1108 AllocationContext_t context = AllocationContext::current(); 1109 HeapWord* result = _allocator->attempt_allocation(word_size, context); 1110 1111 if (result == NULL) { 1112 result = attempt_allocation_slow(word_size, 1113 context, 1114 gc_count_before_ret, 1115 gclocker_retry_count_ret); 1116 } 1117 assert_heap_not_locked(); 1118 if (result != NULL) { 1119 dirty_young_block(result, word_size); 1120 } 1121 return result; 1122 } 1123 1124 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 1125 assert(!is_init_completed(), "Expect to be called at JVM init time"); 1126 assert(ranges != NULL, "MemRegion array NULL"); 1127 assert(count != 0, "No MemRegions provided"); 1128 MemRegion reserved = _hrm.reserved(); 1129 HeapWord* prev_last_addr = NULL; 1130 HeapRegion* prev_last_region = NULL; 1131 size_t size_used = 0; 1132 size_t uncommitted_regions = 0; 1133 1134 // For each Memregion, free the G1 regions that constitute it, and 1135 // notify mark-sweep that the range is no longer to be considered 'archive.' 1136 MutexLockerEx x(Heap_lock); 1137 for (size_t i = 0; i < count; i++) { 1138 HeapWord* start_address = ranges[i].start(); 1139 HeapWord* last_address = ranges[i].last(); 1140 1141 assert(reserved.contains(start_address) && reserved.contains(last_address), 1142 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 1143 p2i(start_address), p2i(last_address))); 1144 assert(start_address > prev_last_addr, 1145 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 1146 p2i(start_address), p2i(prev_last_addr))); 1147 size_used += ranges[i].byte_size(); 1148 prev_last_addr = last_address; 1149 1150 HeapRegion* start_region = _hrm.addr_to_region(start_address); 1151 HeapRegion* last_region = _hrm.addr_to_region(last_address); 1152 1153 // Check for ranges that start in the same G1 region in which the previous 1154 // range ended, and adjust the start address so we don't try to free 1155 // the same region again. If the current range is entirely within that 1156 // region, skip it. 1157 if (start_region == prev_last_region) { 1158 start_address = start_region->end(); 1159 if (start_address > last_address) { 1160 continue; 1161 } 1162 start_region = _hrm.addr_to_region(start_address); 1163 } 1164 prev_last_region = last_region; 1165 1166 // After verifying that each region was marked as an archive region by 1167 // alloc_archive_regions, set it free and empty and uncommit it. 1168 HeapRegion* curr_region = start_region; 1169 while (curr_region != NULL) { 1170 guarantee(curr_region->is_archive(), 1171 err_msg("Expected archive region at index %u", curr_region->hrm_index())); 1172 uint curr_index = curr_region->hrm_index(); 1173 _old_set.remove(curr_region); 1174 curr_region->set_free(); 1175 curr_region->set_top(curr_region->bottom()); 1176 if (curr_region != last_region) { 1177 curr_region = _hrm.next_region_in_heap(curr_region); 1178 } else { 1179 curr_region = NULL; 1180 } 1181 _hrm.shrink_at(curr_index, 1); 1182 uncommitted_regions++; 1183 } 1184 1185 // Notify mark-sweep that this is no longer an archive range. 1186 G1MarkSweep::set_range_archive(ranges[i], false); 1187 } 1188 1189 if (uncommitted_regions != 0) { 1190 ergo_verbose1(ErgoHeapSizing, 1191 "attempt heap shrinking", 1192 ergo_format_reason("uncommitted archive regions") 1193 ergo_format_byte("total size"), 1194 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 1195 } 1196 decrease_used(size_used); 1197 } 1198 1199 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 1200 uint* gc_count_before_ret, 1201 uint* gclocker_retry_count_ret) { 1202 // The structure of this method has a lot of similarities to 1203 // attempt_allocation_slow(). The reason these two were not merged 1204 // into a single one is that such a method would require several "if 1205 // allocation is not humongous do this, otherwise do that" 1206 // conditional paths which would obscure its flow. In fact, an early 1207 // version of this code did use a unified method which was harder to 1208 // follow and, as a result, it had subtle bugs that were hard to 1209 // track down. So keeping these two methods separate allows each to 1210 // be more readable. It will be good to keep these two in sync as 1211 // much as possible. 1212 1213 assert_heap_not_locked_and_not_at_safepoint(); 1214 assert(is_humongous(word_size), "attempt_allocation_humongous() " 1215 "should only be called for humongous allocations"); 1216 1217 // Humongous objects can exhaust the heap quickly, so we should check if we 1218 // need to start a marking cycle at each humongous object allocation. We do 1219 // the check before we do the actual allocation. The reason for doing it 1220 // before the allocation is that we avoid having to keep track of the newly 1221 // allocated memory while we do a GC. 1222 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1223 word_size)) { 1224 collect(GCCause::_g1_humongous_allocation); 1225 } 1226 1227 // We will loop until a) we manage to successfully perform the 1228 // allocation or b) we successfully schedule a collection which 1229 // fails to perform the allocation. b) is the only case when we'll 1230 // return NULL. 1231 HeapWord* result = NULL; 1232 for (int try_count = 1; /* we'll return */; try_count += 1) { 1233 bool should_try_gc; 1234 uint gc_count_before; 1235 1236 { 1237 MutexLockerEx x(Heap_lock); 1238 1239 // Given that humongous objects are not allocated in young 1240 // regions, we'll first try to do the allocation without doing a 1241 // collection hoping that there's enough space in the heap. 1242 result = humongous_obj_allocate(word_size, AllocationContext::current()); 1243 if (result != NULL) { 1244 return result; 1245 } 1246 1247 if (GC_locker::is_active_and_needs_gc()) { 1248 should_try_gc = false; 1249 } else { 1250 // The GCLocker may not be active but the GCLocker initiated 1251 // GC may not yet have been performed (GCLocker::needs_gc() 1252 // returns true). In this case we do not try this GC and 1253 // wait until the GCLocker initiated GC is performed, and 1254 // then retry the allocation. 1255 if (GC_locker::needs_gc()) { 1256 should_try_gc = false; 1257 } else { 1258 // Read the GC count while still holding the Heap_lock. 1259 gc_count_before = total_collections(); 1260 should_try_gc = true; 1261 } 1262 } 1263 } 1264 1265 if (should_try_gc) { 1266 // If we failed to allocate the humongous object, we should try to 1267 // do a collection pause (if we're allowed) in case it reclaims 1268 // enough space for the allocation to succeed after the pause. 1269 1270 bool succeeded; 1271 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1272 GCCause::_g1_humongous_allocation); 1273 if (result != NULL) { 1274 assert(succeeded, "only way to get back a non-NULL result"); 1275 return result; 1276 } 1277 1278 if (succeeded) { 1279 // If we get here we successfully scheduled a collection which 1280 // failed to allocate. No point in trying to allocate 1281 // further. We'll just return NULL. 1282 MutexLockerEx x(Heap_lock); 1283 *gc_count_before_ret = total_collections(); 1284 return NULL; 1285 } 1286 } else { 1287 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1288 MutexLockerEx x(Heap_lock); 1289 *gc_count_before_ret = total_collections(); 1290 return NULL; 1291 } 1292 // The GCLocker is either active or the GCLocker initiated 1293 // GC has not yet been performed. Stall until it is and 1294 // then retry the allocation. 1295 GC_locker::stall_until_clear(); 1296 (*gclocker_retry_count_ret) += 1; 1297 } 1298 1299 // We can reach here if we were unsuccessful in scheduling a 1300 // collection (because another thread beat us to it) or if we were 1301 // stalled due to the GC locker. In either can we should retry the 1302 // allocation attempt in case another thread successfully 1303 // performed a collection and reclaimed enough space. Give a 1304 // warning if we seem to be looping forever. 1305 1306 if ((QueuedAllocationWarningCount > 0) && 1307 (try_count % QueuedAllocationWarningCount == 0)) { 1308 warning("G1CollectedHeap::attempt_allocation_humongous() " 1309 "retries %d times", try_count); 1310 } 1311 } 1312 1313 ShouldNotReachHere(); 1314 return NULL; 1315 } 1316 1317 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1318 AllocationContext_t context, 1319 bool expect_null_mutator_alloc_region) { 1320 assert_at_safepoint(true /* should_be_vm_thread */); 1321 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region, 1322 "the current alloc region was unexpectedly found to be non-NULL"); 1323 1324 if (!is_humongous(word_size)) { 1325 return _allocator->attempt_allocation_locked(word_size, context); 1326 } else { 1327 HeapWord* result = humongous_obj_allocate(word_size, context); 1328 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1329 collector_state()->set_initiate_conc_mark_if_possible(true); 1330 } 1331 return result; 1332 } 1333 1334 ShouldNotReachHere(); 1335 } 1336 1337 class PostMCRemSetClearClosure: public HeapRegionClosure { 1338 G1CollectedHeap* _g1h; 1339 ModRefBarrierSet* _mr_bs; 1340 public: 1341 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1342 _g1h(g1h), _mr_bs(mr_bs) {} 1343 1344 bool doHeapRegion(HeapRegion* r) { 1345 HeapRegionRemSet* hrrs = r->rem_set(); 1346 1347 if (r->is_continues_humongous()) { 1348 // We'll assert that the strong code root list and RSet is empty 1349 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1350 assert(hrrs->occupied() == 0, "RSet should be empty"); 1351 return false; 1352 } 1353 1354 _g1h->reset_gc_time_stamps(r); 1355 hrrs->clear(); 1356 // You might think here that we could clear just the cards 1357 // corresponding to the used region. But no: if we leave a dirty card 1358 // in a region we might allocate into, then it would prevent that card 1359 // from being enqueued, and cause it to be missed. 1360 // Re: the performance cost: we shouldn't be doing full GC anyway! 1361 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1362 1363 return false; 1364 } 1365 }; 1366 1367 void G1CollectedHeap::clear_rsets_post_compaction() { 1368 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1369 heap_region_iterate(&rs_clear); 1370 } 1371 1372 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1373 G1CollectedHeap* _g1h; 1374 UpdateRSOopClosure _cl; 1375 public: 1376 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) : 1377 _cl(g1->g1_rem_set(), worker_i), 1378 _g1h(g1) 1379 { } 1380 1381 bool doHeapRegion(HeapRegion* r) { 1382 if (!r->is_continues_humongous()) { 1383 _cl.set_from(r); 1384 r->oop_iterate(&_cl); 1385 } 1386 return false; 1387 } 1388 }; 1389 1390 class ParRebuildRSTask: public AbstractGangTask { 1391 G1CollectedHeap* _g1; 1392 HeapRegionClaimer _hrclaimer; 1393 1394 public: 1395 ParRebuildRSTask(G1CollectedHeap* g1) : 1396 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {} 1397 1398 void work(uint worker_id) { 1399 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1400 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer); 1401 } 1402 }; 1403 1404 class PostCompactionPrinterClosure: public HeapRegionClosure { 1405 private: 1406 G1HRPrinter* _hr_printer; 1407 public: 1408 bool doHeapRegion(HeapRegion* hr) { 1409 assert(!hr->is_young(), "not expecting to find young regions"); 1410 if (hr->is_free()) { 1411 // We only generate output for non-empty regions. 1412 } else if (hr->is_starts_humongous()) { 1413 if (hr->region_num() == 1) { 1414 // single humongous region 1415 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1416 } else { 1417 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1418 } 1419 } else if (hr->is_continues_humongous()) { 1420 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1421 } else if (hr->is_archive()) { 1422 _hr_printer->post_compaction(hr, G1HRPrinter::Archive); 1423 } else if (hr->is_old()) { 1424 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1425 } else { 1426 ShouldNotReachHere(); 1427 } 1428 return false; 1429 } 1430 1431 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1432 : _hr_printer(hr_printer) { } 1433 }; 1434 1435 void G1CollectedHeap::print_hrm_post_compaction() { 1436 PostCompactionPrinterClosure cl(hr_printer()); 1437 heap_region_iterate(&cl); 1438 } 1439 1440 bool G1CollectedHeap::do_collection(bool explicit_gc, 1441 bool clear_all_soft_refs, 1442 size_t word_size) { 1443 assert_at_safepoint(true /* should_be_vm_thread */); 1444 1445 if (GC_locker::check_active_before_gc()) { 1446 return false; 1447 } 1448 1449 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1450 gc_timer->register_gc_start(); 1451 1452 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1453 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1454 1455 SvcGCMarker sgcm(SvcGCMarker::FULL); 1456 ResourceMark rm; 1457 1458 G1Log::update_level(); 1459 print_heap_before_gc(); 1460 trace_heap_before_gc(gc_tracer); 1461 1462 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1463 1464 verify_region_sets_optional(); 1465 1466 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1467 collector_policy()->should_clear_all_soft_refs(); 1468 1469 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1470 1471 { 1472 IsGCActiveMark x; 1473 1474 // Timing 1475 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1476 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1477 1478 { 1479 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id()); 1480 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1481 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1482 1483 g1_policy()->record_full_collection_start(); 1484 1485 // Note: When we have a more flexible GC logging framework that 1486 // allows us to add optional attributes to a GC log record we 1487 // could consider timing and reporting how long we wait in the 1488 // following two methods. 1489 wait_while_free_regions_coming(); 1490 // If we start the compaction before the CM threads finish 1491 // scanning the root regions we might trip them over as we'll 1492 // be moving objects / updating references. So let's wait until 1493 // they are done. By telling them to abort, they should complete 1494 // early. 1495 _cm->root_regions()->abort(); 1496 _cm->root_regions()->wait_until_scan_finished(); 1497 append_secondary_free_list_if_not_empty_with_lock(); 1498 1499 gc_prologue(true); 1500 increment_total_collections(true /* full gc */); 1501 increment_old_marking_cycles_started(); 1502 1503 assert(used() == recalculate_used(), "Should be equal"); 1504 1505 verify_before_gc(); 1506 1507 check_bitmaps("Full GC Start"); 1508 pre_full_gc_dump(gc_timer); 1509 1510 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1511 1512 // Disable discovery and empty the discovered lists 1513 // for the CM ref processor. 1514 ref_processor_cm()->disable_discovery(); 1515 ref_processor_cm()->abandon_partial_discovery(); 1516 ref_processor_cm()->verify_no_references_recorded(); 1517 1518 // Abandon current iterations of concurrent marking and concurrent 1519 // refinement, if any are in progress. We have to do this before 1520 // wait_until_scan_finished() below. 1521 concurrent_mark()->abort(); 1522 1523 // Make sure we'll choose a new allocation region afterwards. 1524 _allocator->release_mutator_alloc_region(); 1525 _allocator->abandon_gc_alloc_regions(); 1526 g1_rem_set()->cleanupHRRS(); 1527 1528 // We should call this after we retire any currently active alloc 1529 // regions so that all the ALLOC / RETIRE events are generated 1530 // before the start GC event. 1531 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1532 1533 // We may have added regions to the current incremental collection 1534 // set between the last GC or pause and now. We need to clear the 1535 // incremental collection set and then start rebuilding it afresh 1536 // after this full GC. 1537 abandon_collection_set(g1_policy()->inc_cset_head()); 1538 g1_policy()->clear_incremental_cset(); 1539 g1_policy()->stop_incremental_cset_building(); 1540 1541 tear_down_region_sets(false /* free_list_only */); 1542 collector_state()->set_gcs_are_young(true); 1543 1544 // See the comments in g1CollectedHeap.hpp and 1545 // G1CollectedHeap::ref_processing_init() about 1546 // how reference processing currently works in G1. 1547 1548 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1549 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1550 1551 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1552 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1553 1554 ref_processor_stw()->enable_discovery(); 1555 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1556 1557 // Do collection work 1558 { 1559 HandleMark hm; // Discard invalid handles created during gc 1560 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1561 } 1562 1563 assert(num_free_regions() == 0, "we should not have added any free regions"); 1564 rebuild_region_sets(false /* free_list_only */); 1565 1566 // Enqueue any discovered reference objects that have 1567 // not been removed from the discovered lists. 1568 ref_processor_stw()->enqueue_discovered_references(); 1569 1570 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1571 1572 MemoryService::track_memory_usage(); 1573 1574 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1575 ref_processor_stw()->verify_no_references_recorded(); 1576 1577 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1578 ClassLoaderDataGraph::purge(); 1579 MetaspaceAux::verify_metrics(); 1580 1581 // Note: since we've just done a full GC, concurrent 1582 // marking is no longer active. Therefore we need not 1583 // re-enable reference discovery for the CM ref processor. 1584 // That will be done at the start of the next marking cycle. 1585 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1586 ref_processor_cm()->verify_no_references_recorded(); 1587 1588 reset_gc_time_stamp(); 1589 // Since everything potentially moved, we will clear all remembered 1590 // sets, and clear all cards. Later we will rebuild remembered 1591 // sets. We will also reset the GC time stamps of the regions. 1592 clear_rsets_post_compaction(); 1593 check_gc_time_stamps(); 1594 1595 // Resize the heap if necessary. 1596 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1597 1598 if (_hr_printer.is_active()) { 1599 // We should do this after we potentially resize the heap so 1600 // that all the COMMIT / UNCOMMIT events are generated before 1601 // the end GC event. 1602 1603 print_hrm_post_compaction(); 1604 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1605 } 1606 1607 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1608 if (hot_card_cache->use_cache()) { 1609 hot_card_cache->reset_card_counts(); 1610 hot_card_cache->reset_hot_cache(); 1611 } 1612 1613 // Rebuild remembered sets of all regions. 1614 uint n_workers = 1615 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1616 workers()->active_workers(), 1617 Threads::number_of_non_daemon_threads()); 1618 workers()->set_active_workers(n_workers); 1619 1620 ParRebuildRSTask rebuild_rs_task(this); 1621 workers()->run_task(&rebuild_rs_task); 1622 1623 // Rebuild the strong code root lists for each region 1624 rebuild_strong_code_roots(); 1625 1626 if (true) { // FIXME 1627 MetaspaceGC::compute_new_size(); 1628 } 1629 1630 #ifdef TRACESPINNING 1631 ParallelTaskTerminator::print_termination_counts(); 1632 #endif 1633 1634 // Discard all rset updates 1635 JavaThread::dirty_card_queue_set().abandon_logs(); 1636 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1637 1638 _young_list->reset_sampled_info(); 1639 // At this point there should be no regions in the 1640 // entire heap tagged as young. 1641 assert(check_young_list_empty(true /* check_heap */), 1642 "young list should be empty at this point"); 1643 1644 // Update the number of full collections that have been completed. 1645 increment_old_marking_cycles_completed(false /* concurrent */); 1646 1647 _hrm.verify_optional(); 1648 verify_region_sets_optional(); 1649 1650 verify_after_gc(); 1651 1652 // Clear the previous marking bitmap, if needed for bitmap verification. 1653 // Note we cannot do this when we clear the next marking bitmap in 1654 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1655 // objects marked during a full GC against the previous bitmap. 1656 // But we need to clear it before calling check_bitmaps below since 1657 // the full GC has compacted objects and updated TAMS but not updated 1658 // the prev bitmap. 1659 if (G1VerifyBitmaps) { 1660 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1661 } 1662 check_bitmaps("Full GC End"); 1663 1664 // Start a new incremental collection set for the next pause 1665 assert(g1_policy()->collection_set() == NULL, "must be"); 1666 g1_policy()->start_incremental_cset_building(); 1667 1668 clear_cset_fast_test(); 1669 1670 _allocator->init_mutator_alloc_region(); 1671 1672 g1_policy()->record_full_collection_end(); 1673 1674 if (G1Log::fine()) { 1675 g1_policy()->print_heap_transition(); 1676 } 1677 1678 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1679 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1680 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1681 // before any GC notifications are raised. 1682 g1mm()->update_sizes(); 1683 1684 gc_epilogue(true); 1685 } 1686 1687 if (G1Log::finer()) { 1688 g1_policy()->print_detailed_heap_transition(true /* full */); 1689 } 1690 1691 print_heap_after_gc(); 1692 trace_heap_after_gc(gc_tracer); 1693 1694 post_full_gc_dump(gc_timer); 1695 1696 gc_timer->register_gc_end(); 1697 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1698 } 1699 1700 return true; 1701 } 1702 1703 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1704 // do_collection() will return whether it succeeded in performing 1705 // the GC. Currently, there is no facility on the 1706 // do_full_collection() API to notify the caller than the collection 1707 // did not succeed (e.g., because it was locked out by the GC 1708 // locker). So, right now, we'll ignore the return value. 1709 bool dummy = do_collection(true, /* explicit_gc */ 1710 clear_all_soft_refs, 1711 0 /* word_size */); 1712 } 1713 1714 // This code is mostly copied from TenuredGeneration. 1715 void 1716 G1CollectedHeap:: 1717 resize_if_necessary_after_full_collection(size_t word_size) { 1718 // Include the current allocation, if any, and bytes that will be 1719 // pre-allocated to support collections, as "used". 1720 const size_t used_after_gc = used(); 1721 const size_t capacity_after_gc = capacity(); 1722 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1723 1724 // This is enforced in arguments.cpp. 1725 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1726 "otherwise the code below doesn't make sense"); 1727 1728 // We don't have floating point command-line arguments 1729 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1730 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1731 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1732 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1733 1734 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1735 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1736 1737 // We have to be careful here as these two calculations can overflow 1738 // 32-bit size_t's. 1739 double used_after_gc_d = (double) used_after_gc; 1740 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1741 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1742 1743 // Let's make sure that they are both under the max heap size, which 1744 // by default will make them fit into a size_t. 1745 double desired_capacity_upper_bound = (double) max_heap_size; 1746 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1747 desired_capacity_upper_bound); 1748 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1749 desired_capacity_upper_bound); 1750 1751 // We can now safely turn them into size_t's. 1752 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1753 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1754 1755 // This assert only makes sense here, before we adjust them 1756 // with respect to the min and max heap size. 1757 assert(minimum_desired_capacity <= maximum_desired_capacity, 1758 err_msg("minimum_desired_capacity = " SIZE_FORMAT ", " 1759 "maximum_desired_capacity = " SIZE_FORMAT, 1760 minimum_desired_capacity, maximum_desired_capacity)); 1761 1762 // Should not be greater than the heap max size. No need to adjust 1763 // it with respect to the heap min size as it's a lower bound (i.e., 1764 // we'll try to make the capacity larger than it, not smaller). 1765 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1766 // Should not be less than the heap min size. No need to adjust it 1767 // with respect to the heap max size as it's an upper bound (i.e., 1768 // we'll try to make the capacity smaller than it, not greater). 1769 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1770 1771 if (capacity_after_gc < minimum_desired_capacity) { 1772 // Don't expand unless it's significant 1773 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1774 ergo_verbose4(ErgoHeapSizing, 1775 "attempt heap expansion", 1776 ergo_format_reason("capacity lower than " 1777 "min desired capacity after Full GC") 1778 ergo_format_byte("capacity") 1779 ergo_format_byte("occupancy") 1780 ergo_format_byte_perc("min desired capacity"), 1781 capacity_after_gc, used_after_gc, 1782 minimum_desired_capacity, (double) MinHeapFreeRatio); 1783 expand(expand_bytes); 1784 1785 // No expansion, now see if we want to shrink 1786 } else if (capacity_after_gc > maximum_desired_capacity) { 1787 // Capacity too large, compute shrinking size 1788 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1789 ergo_verbose4(ErgoHeapSizing, 1790 "attempt heap shrinking", 1791 ergo_format_reason("capacity higher than " 1792 "max desired capacity after Full GC") 1793 ergo_format_byte("capacity") 1794 ergo_format_byte("occupancy") 1795 ergo_format_byte_perc("max desired capacity"), 1796 capacity_after_gc, used_after_gc, 1797 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1798 shrink(shrink_bytes); 1799 } 1800 } 1801 1802 1803 HeapWord* 1804 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1805 AllocationContext_t context, 1806 bool* succeeded) { 1807 assert_at_safepoint(true /* should_be_vm_thread */); 1808 1809 *succeeded = true; 1810 // Let's attempt the allocation first. 1811 HeapWord* result = 1812 attempt_allocation_at_safepoint(word_size, 1813 context, 1814 false /* expect_null_mutator_alloc_region */); 1815 if (result != NULL) { 1816 assert(*succeeded, "sanity"); 1817 return result; 1818 } 1819 1820 // In a G1 heap, we're supposed to keep allocation from failing by 1821 // incremental pauses. Therefore, at least for now, we'll favor 1822 // expansion over collection. (This might change in the future if we can 1823 // do something smarter than full collection to satisfy a failed alloc.) 1824 result = expand_and_allocate(word_size, context); 1825 if (result != NULL) { 1826 assert(*succeeded, "sanity"); 1827 return result; 1828 } 1829 1830 // Expansion didn't work, we'll try to do a Full GC. 1831 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1832 false, /* clear_all_soft_refs */ 1833 word_size); 1834 if (!gc_succeeded) { 1835 *succeeded = false; 1836 return NULL; 1837 } 1838 1839 // Retry the allocation 1840 result = attempt_allocation_at_safepoint(word_size, 1841 context, 1842 true /* expect_null_mutator_alloc_region */); 1843 if (result != NULL) { 1844 assert(*succeeded, "sanity"); 1845 return result; 1846 } 1847 1848 // Then, try a Full GC that will collect all soft references. 1849 gc_succeeded = do_collection(false, /* explicit_gc */ 1850 true, /* clear_all_soft_refs */ 1851 word_size); 1852 if (!gc_succeeded) { 1853 *succeeded = false; 1854 return NULL; 1855 } 1856 1857 // Retry the allocation once more 1858 result = attempt_allocation_at_safepoint(word_size, 1859 context, 1860 true /* expect_null_mutator_alloc_region */); 1861 if (result != NULL) { 1862 assert(*succeeded, "sanity"); 1863 return result; 1864 } 1865 1866 assert(!collector_policy()->should_clear_all_soft_refs(), 1867 "Flag should have been handled and cleared prior to this point"); 1868 1869 // What else? We might try synchronous finalization later. If the total 1870 // space available is large enough for the allocation, then a more 1871 // complete compaction phase than we've tried so far might be 1872 // appropriate. 1873 assert(*succeeded, "sanity"); 1874 return NULL; 1875 } 1876 1877 // Attempting to expand the heap sufficiently 1878 // to support an allocation of the given "word_size". If 1879 // successful, perform the allocation and return the address of the 1880 // allocated block, or else "NULL". 1881 1882 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1883 assert_at_safepoint(true /* should_be_vm_thread */); 1884 1885 verify_region_sets_optional(); 1886 1887 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1888 ergo_verbose1(ErgoHeapSizing, 1889 "attempt heap expansion", 1890 ergo_format_reason("allocation request failed") 1891 ergo_format_byte("allocation request"), 1892 word_size * HeapWordSize); 1893 if (expand(expand_bytes)) { 1894 _hrm.verify_optional(); 1895 verify_region_sets_optional(); 1896 return attempt_allocation_at_safepoint(word_size, 1897 context, 1898 false /* expect_null_mutator_alloc_region */); 1899 } 1900 return NULL; 1901 } 1902 1903 bool G1CollectedHeap::expand(size_t expand_bytes) { 1904 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1905 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1906 HeapRegion::GrainBytes); 1907 ergo_verbose2(ErgoHeapSizing, 1908 "expand the heap", 1909 ergo_format_byte("requested expansion amount") 1910 ergo_format_byte("attempted expansion amount"), 1911 expand_bytes, aligned_expand_bytes); 1912 1913 if (is_maximal_no_gc()) { 1914 ergo_verbose0(ErgoHeapSizing, 1915 "did not expand the heap", 1916 ergo_format_reason("heap already fully expanded")); 1917 return false; 1918 } 1919 1920 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1921 assert(regions_to_expand > 0, "Must expand by at least one region"); 1922 1923 uint expanded_by = _hrm.expand_by(regions_to_expand); 1924 1925 if (expanded_by > 0) { 1926 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1927 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1928 g1_policy()->record_new_heap_size(num_regions()); 1929 } else { 1930 ergo_verbose0(ErgoHeapSizing, 1931 "did not expand the heap", 1932 ergo_format_reason("heap expansion operation failed")); 1933 // The expansion of the virtual storage space was unsuccessful. 1934 // Let's see if it was because we ran out of swap. 1935 if (G1ExitOnExpansionFailure && 1936 _hrm.available() >= regions_to_expand) { 1937 // We had head room... 1938 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1939 } 1940 } 1941 return regions_to_expand > 0; 1942 } 1943 1944 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1945 size_t aligned_shrink_bytes = 1946 ReservedSpace::page_align_size_down(shrink_bytes); 1947 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1948 HeapRegion::GrainBytes); 1949 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1950 1951 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1952 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1953 1954 ergo_verbose3(ErgoHeapSizing, 1955 "shrink the heap", 1956 ergo_format_byte("requested shrinking amount") 1957 ergo_format_byte("aligned shrinking amount") 1958 ergo_format_byte("attempted shrinking amount"), 1959 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1960 if (num_regions_removed > 0) { 1961 g1_policy()->record_new_heap_size(num_regions()); 1962 } else { 1963 ergo_verbose0(ErgoHeapSizing, 1964 "did not shrink the heap", 1965 ergo_format_reason("heap shrinking operation failed")); 1966 } 1967 } 1968 1969 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1970 verify_region_sets_optional(); 1971 1972 // We should only reach here at the end of a Full GC which means we 1973 // should not not be holding to any GC alloc regions. The method 1974 // below will make sure of that and do any remaining clean up. 1975 _allocator->abandon_gc_alloc_regions(); 1976 1977 // Instead of tearing down / rebuilding the free lists here, we 1978 // could instead use the remove_all_pending() method on free_list to 1979 // remove only the ones that we need to remove. 1980 tear_down_region_sets(true /* free_list_only */); 1981 shrink_helper(shrink_bytes); 1982 rebuild_region_sets(true /* free_list_only */); 1983 1984 _hrm.verify_optional(); 1985 verify_region_sets_optional(); 1986 } 1987 1988 // Public methods. 1989 1990 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1991 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1992 #endif // _MSC_VER 1993 1994 1995 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1996 CollectedHeap(), 1997 _g1_policy(policy_), 1998 _dirty_card_queue_set(false), 1999 _into_cset_dirty_card_queue_set(false), 2000 _is_alive_closure_cm(this), 2001 _is_alive_closure_stw(this), 2002 _ref_processor_cm(NULL), 2003 _ref_processor_stw(NULL), 2004 _bot_shared(NULL), 2005 _cg1r(NULL), 2006 _g1mm(NULL), 2007 _refine_cte_cl(NULL), 2008 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 2009 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 2010 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 2011 _humongous_reclaim_candidates(), 2012 _has_humongous_reclaim_candidates(false), 2013 _archive_allocator(NULL), 2014 _free_regions_coming(false), 2015 _young_list(new YoungList(this)), 2016 _gc_time_stamp(0), 2017 _summary_bytes_used(0), 2018 _survivor_evac_stats(YoungPLABSize, PLABWeight), 2019 _old_evac_stats(OldPLABSize, PLABWeight), 2020 _expand_heap_after_alloc_failure(true), 2021 _old_marking_cycles_started(0), 2022 _old_marking_cycles_completed(0), 2023 _heap_summary_sent(false), 2024 _in_cset_fast_test(), 2025 _dirty_cards_region_list(NULL), 2026 _worker_cset_start_region(NULL), 2027 _worker_cset_start_region_time_stamp(NULL), 2028 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 2029 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 2030 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 2031 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 2032 2033 _workers = new WorkGang("GC Thread", ParallelGCThreads, 2034 /* are_GC_task_threads */true, 2035 /* are_ConcurrentGC_threads */false); 2036 _workers->initialize_workers(); 2037 2038 _allocator = G1Allocator::create_allocator(this); 2039 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 2040 2041 // Override the default _filler_array_max_size so that no humongous filler 2042 // objects are created. 2043 _filler_array_max_size = _humongous_object_threshold_in_words; 2044 2045 uint n_queues = ParallelGCThreads; 2046 _task_queues = new RefToScanQueueSet(n_queues); 2047 2048 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 2049 assert(n_rem_sets > 0, "Invariant."); 2050 2051 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 2052 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC); 2053 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 2054 2055 for (uint i = 0; i < n_queues; i++) { 2056 RefToScanQueue* q = new RefToScanQueue(); 2057 q->initialize(); 2058 _task_queues->register_queue(i, q); 2059 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 2060 } 2061 clear_cset_start_regions(); 2062 2063 // Initialize the G1EvacuationFailureALot counters and flags. 2064 NOT_PRODUCT(reset_evacuation_should_fail();) 2065 2066 guarantee(_task_queues != NULL, "task_queues allocation failure."); 2067 } 2068 2069 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 2070 size_t size, 2071 size_t translation_factor) { 2072 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 2073 // Allocate a new reserved space, preferring to use large pages. 2074 ReservedSpace rs(size, preferred_page_size); 2075 G1RegionToSpaceMapper* result = 2076 G1RegionToSpaceMapper::create_mapper(rs, 2077 size, 2078 rs.alignment(), 2079 HeapRegion::GrainBytes, 2080 translation_factor, 2081 mtGC); 2082 if (TracePageSizes) { 2083 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT, 2084 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size); 2085 } 2086 return result; 2087 } 2088 2089 jint G1CollectedHeap::initialize() { 2090 CollectedHeap::pre_initialize(); 2091 os::enable_vtime(); 2092 2093 G1Log::init(); 2094 2095 // Necessary to satisfy locking discipline assertions. 2096 2097 MutexLocker x(Heap_lock); 2098 2099 // We have to initialize the printer before committing the heap, as 2100 // it will be used then. 2101 _hr_printer.set_active(G1PrintHeapRegions); 2102 2103 // While there are no constraints in the GC code that HeapWordSize 2104 // be any particular value, there are multiple other areas in the 2105 // system which believe this to be true (e.g. oop->object_size in some 2106 // cases incorrectly returns the size in wordSize units rather than 2107 // HeapWordSize). 2108 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 2109 2110 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 2111 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 2112 size_t heap_alignment = collector_policy()->heap_alignment(); 2113 2114 // Ensure that the sizes are properly aligned. 2115 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2116 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2117 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 2118 2119 _refine_cte_cl = new RefineCardTableEntryClosure(); 2120 2121 jint ecode = JNI_OK; 2122 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode); 2123 if (_cg1r == NULL) { 2124 return ecode; 2125 } 2126 2127 // Reserve the maximum. 2128 2129 // When compressed oops are enabled, the preferred heap base 2130 // is calculated by subtracting the requested size from the 2131 // 32Gb boundary and using the result as the base address for 2132 // heap reservation. If the requested size is not aligned to 2133 // HeapRegion::GrainBytes (i.e. the alignment that is passed 2134 // into the ReservedHeapSpace constructor) then the actual 2135 // base of the reserved heap may end up differing from the 2136 // address that was requested (i.e. the preferred heap base). 2137 // If this happens then we could end up using a non-optimal 2138 // compressed oops mode. 2139 2140 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 2141 heap_alignment); 2142 2143 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 2144 2145 // Create the barrier set for the entire reserved region. 2146 G1SATBCardTableLoggingModRefBS* bs 2147 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 2148 bs->initialize(); 2149 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 2150 set_barrier_set(bs); 2151 2152 // Also create a G1 rem set. 2153 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 2154 2155 // Carve out the G1 part of the heap. 2156 2157 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 2158 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 2159 G1RegionToSpaceMapper* heap_storage = 2160 G1RegionToSpaceMapper::create_mapper(g1_rs, 2161 g1_rs.size(), 2162 page_size, 2163 HeapRegion::GrainBytes, 2164 1, 2165 mtJavaHeap); 2166 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(), 2167 max_byte_size, page_size, 2168 heap_rs.base(), 2169 heap_rs.size()); 2170 heap_storage->set_mapping_changed_listener(&_listener); 2171 2172 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 2173 G1RegionToSpaceMapper* bot_storage = 2174 create_aux_memory_mapper("Block offset table", 2175 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize), 2176 G1BlockOffsetSharedArray::heap_map_factor()); 2177 2178 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 2179 G1RegionToSpaceMapper* cardtable_storage = 2180 create_aux_memory_mapper("Card table", 2181 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize), 2182 G1SATBCardTableLoggingModRefBS::heap_map_factor()); 2183 2184 G1RegionToSpaceMapper* card_counts_storage = 2185 create_aux_memory_mapper("Card counts table", 2186 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 2187 G1CardCounts::heap_map_factor()); 2188 2189 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); 2190 G1RegionToSpaceMapper* prev_bitmap_storage = 2191 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor()); 2192 G1RegionToSpaceMapper* next_bitmap_storage = 2193 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor()); 2194 2195 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 2196 g1_barrier_set()->initialize(cardtable_storage); 2197 // Do later initialization work for concurrent refinement. 2198 _cg1r->init(card_counts_storage); 2199 2200 // 6843694 - ensure that the maximum region index can fit 2201 // in the remembered set structures. 2202 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2203 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2204 2205 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2206 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2207 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2208 "too many cards per region"); 2209 2210 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 2211 2212 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage); 2213 2214 { 2215 HeapWord* start = _hrm.reserved().start(); 2216 HeapWord* end = _hrm.reserved().end(); 2217 size_t granularity = HeapRegion::GrainBytes; 2218 2219 _in_cset_fast_test.initialize(start, end, granularity); 2220 _humongous_reclaim_candidates.initialize(start, end, granularity); 2221 } 2222 2223 // Create the ConcurrentMark data structure and thread. 2224 // (Must do this late, so that "max_regions" is defined.) 2225 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 2226 if (_cm == NULL || !_cm->completed_initialization()) { 2227 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 2228 return JNI_ENOMEM; 2229 } 2230 _cmThread = _cm->cmThread(); 2231 2232 // Initialize the from_card cache structure of HeapRegionRemSet. 2233 HeapRegionRemSet::init_heap(max_regions()); 2234 2235 // Now expand into the initial heap size. 2236 if (!expand(init_byte_size)) { 2237 vm_shutdown_during_initialization("Failed to allocate initial heap."); 2238 return JNI_ENOMEM; 2239 } 2240 2241 // Perform any initialization actions delegated to the policy. 2242 g1_policy()->init(); 2243 2244 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2245 SATB_Q_FL_lock, 2246 G1SATBProcessCompletedThreshold, 2247 Shared_SATB_Q_lock); 2248 2249 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 2250 DirtyCardQ_CBL_mon, 2251 DirtyCardQ_FL_lock, 2252 concurrent_g1_refine()->yellow_zone(), 2253 concurrent_g1_refine()->red_zone(), 2254 Shared_DirtyCardQ_lock); 2255 2256 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 2257 DirtyCardQ_CBL_mon, 2258 DirtyCardQ_FL_lock, 2259 -1, // never trigger processing 2260 -1, // no limit on length 2261 Shared_DirtyCardQ_lock, 2262 &JavaThread::dirty_card_queue_set()); 2263 2264 // Initialize the card queue set used to hold cards containing 2265 // references into the collection set. 2266 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 2267 DirtyCardQ_CBL_mon, 2268 DirtyCardQ_FL_lock, 2269 -1, // never trigger processing 2270 -1, // no limit on length 2271 Shared_DirtyCardQ_lock, 2272 &JavaThread::dirty_card_queue_set()); 2273 2274 // Here we allocate the dummy HeapRegion that is required by the 2275 // G1AllocRegion class. 2276 HeapRegion* dummy_region = _hrm.get_dummy_region(); 2277 2278 // We'll re-use the same region whether the alloc region will 2279 // require BOT updates or not and, if it doesn't, then a non-young 2280 // region will complain that it cannot support allocations without 2281 // BOT updates. So we'll tag the dummy region as eden to avoid that. 2282 dummy_region->set_eden(); 2283 // Make sure it's full. 2284 dummy_region->set_top(dummy_region->end()); 2285 G1AllocRegion::setup(this, dummy_region); 2286 2287 _allocator->init_mutator_alloc_region(); 2288 2289 // Do create of the monitoring and management support so that 2290 // values in the heap have been properly initialized. 2291 _g1mm = new G1MonitoringSupport(this); 2292 2293 G1StringDedup::initialize(); 2294 2295 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC); 2296 for (uint i = 0; i < ParallelGCThreads; i++) { 2297 new (&_preserved_objs[i]) OopAndMarkOopStack(); 2298 } 2299 2300 return JNI_OK; 2301 } 2302 2303 void G1CollectedHeap::stop() { 2304 // Stop all concurrent threads. We do this to make sure these threads 2305 // do not continue to execute and access resources (e.g. gclog_or_tty) 2306 // that are destroyed during shutdown. 2307 _cg1r->stop(); 2308 _cmThread->stop(); 2309 if (G1StringDedup::is_enabled()) { 2310 G1StringDedup::stop(); 2311 } 2312 } 2313 2314 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2315 return HeapRegion::max_region_size(); 2316 } 2317 2318 void G1CollectedHeap::post_initialize() { 2319 CollectedHeap::post_initialize(); 2320 ref_processing_init(); 2321 } 2322 2323 void G1CollectedHeap::ref_processing_init() { 2324 // Reference processing in G1 currently works as follows: 2325 // 2326 // * There are two reference processor instances. One is 2327 // used to record and process discovered references 2328 // during concurrent marking; the other is used to 2329 // record and process references during STW pauses 2330 // (both full and incremental). 2331 // * Both ref processors need to 'span' the entire heap as 2332 // the regions in the collection set may be dotted around. 2333 // 2334 // * For the concurrent marking ref processor: 2335 // * Reference discovery is enabled at initial marking. 2336 // * Reference discovery is disabled and the discovered 2337 // references processed etc during remarking. 2338 // * Reference discovery is MT (see below). 2339 // * Reference discovery requires a barrier (see below). 2340 // * Reference processing may or may not be MT 2341 // (depending on the value of ParallelRefProcEnabled 2342 // and ParallelGCThreads). 2343 // * A full GC disables reference discovery by the CM 2344 // ref processor and abandons any entries on it's 2345 // discovered lists. 2346 // 2347 // * For the STW processor: 2348 // * Non MT discovery is enabled at the start of a full GC. 2349 // * Processing and enqueueing during a full GC is non-MT. 2350 // * During a full GC, references are processed after marking. 2351 // 2352 // * Discovery (may or may not be MT) is enabled at the start 2353 // of an incremental evacuation pause. 2354 // * References are processed near the end of a STW evacuation pause. 2355 // * For both types of GC: 2356 // * Discovery is atomic - i.e. not concurrent. 2357 // * Reference discovery will not need a barrier. 2358 2359 MemRegion mr = reserved_region(); 2360 2361 // Concurrent Mark ref processor 2362 _ref_processor_cm = 2363 new ReferenceProcessor(mr, // span 2364 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2365 // mt processing 2366 ParallelGCThreads, 2367 // degree of mt processing 2368 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2369 // mt discovery 2370 MAX2(ParallelGCThreads, ConcGCThreads), 2371 // degree of mt discovery 2372 false, 2373 // Reference discovery is not atomic 2374 &_is_alive_closure_cm); 2375 // is alive closure 2376 // (for efficiency/performance) 2377 2378 // STW ref processor 2379 _ref_processor_stw = 2380 new ReferenceProcessor(mr, // span 2381 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2382 // mt processing 2383 ParallelGCThreads, 2384 // degree of mt processing 2385 (ParallelGCThreads > 1), 2386 // mt discovery 2387 ParallelGCThreads, 2388 // degree of mt discovery 2389 true, 2390 // Reference discovery is atomic 2391 &_is_alive_closure_stw); 2392 // is alive closure 2393 // (for efficiency/performance) 2394 } 2395 2396 CollectorPolicy* G1CollectedHeap::collector_policy() const { 2397 return g1_policy(); 2398 } 2399 2400 size_t G1CollectedHeap::capacity() const { 2401 return _hrm.length() * HeapRegion::GrainBytes; 2402 } 2403 2404 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2405 assert(!hr->is_continues_humongous(), "pre-condition"); 2406 hr->reset_gc_time_stamp(); 2407 if (hr->is_starts_humongous()) { 2408 uint first_index = hr->hrm_index() + 1; 2409 uint last_index = hr->last_hc_index(); 2410 for (uint i = first_index; i < last_index; i += 1) { 2411 HeapRegion* chr = region_at(i); 2412 assert(chr->is_continues_humongous(), "sanity"); 2413 chr->reset_gc_time_stamp(); 2414 } 2415 } 2416 } 2417 2418 #ifndef PRODUCT 2419 2420 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2421 private: 2422 unsigned _gc_time_stamp; 2423 bool _failures; 2424 2425 public: 2426 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2427 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2428 2429 virtual bool doHeapRegion(HeapRegion* hr) { 2430 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2431 if (_gc_time_stamp != region_gc_time_stamp) { 2432 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, " 2433 "expected %d", HR_FORMAT_PARAMS(hr), 2434 region_gc_time_stamp, _gc_time_stamp); 2435 _failures = true; 2436 } 2437 return false; 2438 } 2439 2440 bool failures() { return _failures; } 2441 }; 2442 2443 void G1CollectedHeap::check_gc_time_stamps() { 2444 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2445 heap_region_iterate(&cl); 2446 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2447 } 2448 #endif // PRODUCT 2449 2450 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2451 DirtyCardQueue* into_cset_dcq, 2452 bool concurrent, 2453 uint worker_i) { 2454 // Clean cards in the hot card cache 2455 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2456 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2457 2458 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2459 size_t n_completed_buffers = 0; 2460 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2461 n_completed_buffers++; 2462 } 2463 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 2464 dcqs.clear_n_completed_buffers(); 2465 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2466 } 2467 2468 // Computes the sum of the storage used by the various regions. 2469 size_t G1CollectedHeap::used() const { 2470 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 2471 if (_archive_allocator != NULL) { 2472 result += _archive_allocator->used(); 2473 } 2474 return result; 2475 } 2476 2477 size_t G1CollectedHeap::used_unlocked() const { 2478 return _summary_bytes_used; 2479 } 2480 2481 class SumUsedClosure: public HeapRegionClosure { 2482 size_t _used; 2483 public: 2484 SumUsedClosure() : _used(0) {} 2485 bool doHeapRegion(HeapRegion* r) { 2486 if (!r->is_continues_humongous()) { 2487 _used += r->used(); 2488 } 2489 return false; 2490 } 2491 size_t result() { return _used; } 2492 }; 2493 2494 size_t G1CollectedHeap::recalculate_used() const { 2495 double recalculate_used_start = os::elapsedTime(); 2496 2497 SumUsedClosure blk; 2498 heap_region_iterate(&blk); 2499 2500 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2501 return blk.result(); 2502 } 2503 2504 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2505 switch (cause) { 2506 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2507 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2508 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 2509 case GCCause::_g1_humongous_allocation: return true; 2510 case GCCause::_update_allocation_context_stats_inc: return true; 2511 case GCCause::_wb_conc_mark: return true; 2512 default: return false; 2513 } 2514 } 2515 2516 #ifndef PRODUCT 2517 void G1CollectedHeap::allocate_dummy_regions() { 2518 // Let's fill up most of the region 2519 size_t word_size = HeapRegion::GrainWords - 1024; 2520 // And as a result the region we'll allocate will be humongous. 2521 guarantee(is_humongous(word_size), "sanity"); 2522 2523 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2524 // Let's use the existing mechanism for the allocation 2525 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2526 AllocationContext::system()); 2527 if (dummy_obj != NULL) { 2528 MemRegion mr(dummy_obj, word_size); 2529 CollectedHeap::fill_with_object(mr); 2530 } else { 2531 // If we can't allocate once, we probably cannot allocate 2532 // again. Let's get out of the loop. 2533 break; 2534 } 2535 } 2536 } 2537 #endif // !PRODUCT 2538 2539 void G1CollectedHeap::increment_old_marking_cycles_started() { 2540 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2541 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2542 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2543 _old_marking_cycles_started, _old_marking_cycles_completed)); 2544 2545 _old_marking_cycles_started++; 2546 } 2547 2548 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2549 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2550 2551 // We assume that if concurrent == true, then the caller is a 2552 // concurrent thread that was joined the Suspendible Thread 2553 // Set. If there's ever a cheap way to check this, we should add an 2554 // assert here. 2555 2556 // Given that this method is called at the end of a Full GC or of a 2557 // concurrent cycle, and those can be nested (i.e., a Full GC can 2558 // interrupt a concurrent cycle), the number of full collections 2559 // completed should be either one (in the case where there was no 2560 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2561 // behind the number of full collections started. 2562 2563 // This is the case for the inner caller, i.e. a Full GC. 2564 assert(concurrent || 2565 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2566 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2567 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2568 "is inconsistent with _old_marking_cycles_completed = %u", 2569 _old_marking_cycles_started, _old_marking_cycles_completed)); 2570 2571 // This is the case for the outer caller, i.e. the concurrent cycle. 2572 assert(!concurrent || 2573 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2574 err_msg("for outer caller (concurrent cycle): " 2575 "_old_marking_cycles_started = %u " 2576 "is inconsistent with _old_marking_cycles_completed = %u", 2577 _old_marking_cycles_started, _old_marking_cycles_completed)); 2578 2579 _old_marking_cycles_completed += 1; 2580 2581 // We need to clear the "in_progress" flag in the CM thread before 2582 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2583 // is set) so that if a waiter requests another System.gc() it doesn't 2584 // incorrectly see that a marking cycle is still in progress. 2585 if (concurrent) { 2586 _cmThread->set_idle(); 2587 } 2588 2589 // This notify_all() will ensure that a thread that called 2590 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2591 // and it's waiting for a full GC to finish will be woken up. It is 2592 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2593 FullGCCount_lock->notify_all(); 2594 } 2595 2596 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2597 collector_state()->set_concurrent_cycle_started(true); 2598 _gc_timer_cm->register_gc_start(start_time); 2599 2600 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2601 trace_heap_before_gc(_gc_tracer_cm); 2602 } 2603 2604 void G1CollectedHeap::register_concurrent_cycle_end() { 2605 if (collector_state()->concurrent_cycle_started()) { 2606 if (_cm->has_aborted()) { 2607 _gc_tracer_cm->report_concurrent_mode_failure(); 2608 } 2609 2610 _gc_timer_cm->register_gc_end(); 2611 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2612 2613 // Clear state variables to prepare for the next concurrent cycle. 2614 collector_state()->set_concurrent_cycle_started(false); 2615 _heap_summary_sent = false; 2616 } 2617 } 2618 2619 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2620 if (collector_state()->concurrent_cycle_started()) { 2621 // This function can be called when: 2622 // the cleanup pause is run 2623 // the concurrent cycle is aborted before the cleanup pause. 2624 // the concurrent cycle is aborted after the cleanup pause, 2625 // but before the concurrent cycle end has been registered. 2626 // Make sure that we only send the heap information once. 2627 if (!_heap_summary_sent) { 2628 trace_heap_after_gc(_gc_tracer_cm); 2629 _heap_summary_sent = true; 2630 } 2631 } 2632 } 2633 2634 void G1CollectedHeap::collect(GCCause::Cause cause) { 2635 assert_heap_not_locked(); 2636 2637 uint gc_count_before; 2638 uint old_marking_count_before; 2639 uint full_gc_count_before; 2640 bool retry_gc; 2641 2642 do { 2643 retry_gc = false; 2644 2645 { 2646 MutexLocker ml(Heap_lock); 2647 2648 // Read the GC count while holding the Heap_lock 2649 gc_count_before = total_collections(); 2650 full_gc_count_before = total_full_collections(); 2651 old_marking_count_before = _old_marking_cycles_started; 2652 } 2653 2654 if (should_do_concurrent_full_gc(cause)) { 2655 // Schedule an initial-mark evacuation pause that will start a 2656 // concurrent cycle. We're setting word_size to 0 which means that 2657 // we are not requesting a post-GC allocation. 2658 VM_G1IncCollectionPause op(gc_count_before, 2659 0, /* word_size */ 2660 true, /* should_initiate_conc_mark */ 2661 g1_policy()->max_pause_time_ms(), 2662 cause); 2663 op.set_allocation_context(AllocationContext::current()); 2664 2665 VMThread::execute(&op); 2666 if (!op.pause_succeeded()) { 2667 if (old_marking_count_before == _old_marking_cycles_started) { 2668 retry_gc = op.should_retry_gc(); 2669 } else { 2670 // A Full GC happened while we were trying to schedule the 2671 // initial-mark GC. No point in starting a new cycle given 2672 // that the whole heap was collected anyway. 2673 } 2674 2675 if (retry_gc) { 2676 if (GC_locker::is_active_and_needs_gc()) { 2677 GC_locker::stall_until_clear(); 2678 } 2679 } 2680 } 2681 } else { 2682 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2683 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2684 2685 // Schedule a standard evacuation pause. We're setting word_size 2686 // to 0 which means that we are not requesting a post-GC allocation. 2687 VM_G1IncCollectionPause op(gc_count_before, 2688 0, /* word_size */ 2689 false, /* should_initiate_conc_mark */ 2690 g1_policy()->max_pause_time_ms(), 2691 cause); 2692 VMThread::execute(&op); 2693 } else { 2694 // Schedule a Full GC. 2695 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2696 VMThread::execute(&op); 2697 } 2698 } 2699 } while (retry_gc); 2700 } 2701 2702 bool G1CollectedHeap::is_in(const void* p) const { 2703 if (_hrm.reserved().contains(p)) { 2704 // Given that we know that p is in the reserved space, 2705 // heap_region_containing_raw() should successfully 2706 // return the containing region. 2707 HeapRegion* hr = heap_region_containing_raw(p); 2708 return hr->is_in(p); 2709 } else { 2710 return false; 2711 } 2712 } 2713 2714 #ifdef ASSERT 2715 bool G1CollectedHeap::is_in_exact(const void* p) const { 2716 bool contains = reserved_region().contains(p); 2717 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2718 if (contains && available) { 2719 return true; 2720 } else { 2721 return false; 2722 } 2723 } 2724 #endif 2725 2726 bool G1CollectedHeap::obj_in_cs(oop obj) { 2727 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj); 2728 return r != NULL && r->in_collection_set(); 2729 } 2730 2731 // Iteration functions. 2732 2733 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2734 2735 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2736 ExtendedOopClosure* _cl; 2737 public: 2738 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2739 bool doHeapRegion(HeapRegion* r) { 2740 if (!r->is_continues_humongous()) { 2741 r->oop_iterate(_cl); 2742 } 2743 return false; 2744 } 2745 }; 2746 2747 // Iterates an ObjectClosure over all objects within a HeapRegion. 2748 2749 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2750 ObjectClosure* _cl; 2751 public: 2752 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2753 bool doHeapRegion(HeapRegion* r) { 2754 if (!r->is_continues_humongous()) { 2755 r->object_iterate(_cl); 2756 } 2757 return false; 2758 } 2759 }; 2760 2761 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2762 IterateObjectClosureRegionClosure blk(cl); 2763 heap_region_iterate(&blk); 2764 } 2765 2766 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2767 _hrm.iterate(cl); 2768 } 2769 2770 void 2771 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, 2772 uint worker_id, 2773 HeapRegionClaimer *hrclaimer, 2774 bool concurrent) const { 2775 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); 2776 } 2777 2778 // Clear the cached CSet starting regions and (more importantly) 2779 // the time stamps. Called when we reset the GC time stamp. 2780 void G1CollectedHeap::clear_cset_start_regions() { 2781 assert(_worker_cset_start_region != NULL, "sanity"); 2782 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2783 2784 for (uint i = 0; i < ParallelGCThreads; i++) { 2785 _worker_cset_start_region[i] = NULL; 2786 _worker_cset_start_region_time_stamp[i] = 0; 2787 } 2788 } 2789 2790 // Given the id of a worker, obtain or calculate a suitable 2791 // starting region for iterating over the current collection set. 2792 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2793 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2794 2795 HeapRegion* result = NULL; 2796 unsigned gc_time_stamp = get_gc_time_stamp(); 2797 2798 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2799 // Cached starting region for current worker was set 2800 // during the current pause - so it's valid. 2801 // Note: the cached starting heap region may be NULL 2802 // (when the collection set is empty). 2803 result = _worker_cset_start_region[worker_i]; 2804 assert(result == NULL || result->in_collection_set(), "sanity"); 2805 return result; 2806 } 2807 2808 // The cached entry was not valid so let's calculate 2809 // a suitable starting heap region for this worker. 2810 2811 // We want the parallel threads to start their collection 2812 // set iteration at different collection set regions to 2813 // avoid contention. 2814 // If we have: 2815 // n collection set regions 2816 // p threads 2817 // Then thread t will start at region floor ((t * n) / p) 2818 2819 result = g1_policy()->collection_set(); 2820 uint cs_size = g1_policy()->cset_region_length(); 2821 uint active_workers = workers()->active_workers(); 2822 2823 uint end_ind = (cs_size * worker_i) / active_workers; 2824 uint start_ind = 0; 2825 2826 if (worker_i > 0 && 2827 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2828 // Previous workers starting region is valid 2829 // so let's iterate from there 2830 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2831 result = _worker_cset_start_region[worker_i - 1]; 2832 } 2833 2834 for (uint i = start_ind; i < end_ind; i++) { 2835 result = result->next_in_collection_set(); 2836 } 2837 2838 // Note: the calculated starting heap region may be NULL 2839 // (when the collection set is empty). 2840 assert(result == NULL || result->in_collection_set(), "sanity"); 2841 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2842 "should be updated only once per pause"); 2843 _worker_cset_start_region[worker_i] = result; 2844 OrderAccess::storestore(); 2845 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2846 return result; 2847 } 2848 2849 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2850 HeapRegion* r = g1_policy()->collection_set(); 2851 while (r != NULL) { 2852 HeapRegion* next = r->next_in_collection_set(); 2853 if (cl->doHeapRegion(r)) { 2854 cl->incomplete(); 2855 return; 2856 } 2857 r = next; 2858 } 2859 } 2860 2861 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2862 HeapRegionClosure *cl) { 2863 if (r == NULL) { 2864 // The CSet is empty so there's nothing to do. 2865 return; 2866 } 2867 2868 assert(r->in_collection_set(), 2869 "Start region must be a member of the collection set."); 2870 HeapRegion* cur = r; 2871 while (cur != NULL) { 2872 HeapRegion* next = cur->next_in_collection_set(); 2873 if (cl->doHeapRegion(cur) && false) { 2874 cl->incomplete(); 2875 return; 2876 } 2877 cur = next; 2878 } 2879 cur = g1_policy()->collection_set(); 2880 while (cur != r) { 2881 HeapRegion* next = cur->next_in_collection_set(); 2882 if (cl->doHeapRegion(cur) && false) { 2883 cl->incomplete(); 2884 return; 2885 } 2886 cur = next; 2887 } 2888 } 2889 2890 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2891 HeapRegion* result = _hrm.next_region_in_heap(from); 2892 while (result != NULL && result->is_pinned()) { 2893 result = _hrm.next_region_in_heap(result); 2894 } 2895 return result; 2896 } 2897 2898 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2899 HeapRegion* hr = heap_region_containing(addr); 2900 return hr->block_start(addr); 2901 } 2902 2903 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2904 HeapRegion* hr = heap_region_containing(addr); 2905 return hr->block_size(addr); 2906 } 2907 2908 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2909 HeapRegion* hr = heap_region_containing(addr); 2910 return hr->block_is_obj(addr); 2911 } 2912 2913 bool G1CollectedHeap::supports_tlab_allocation() const { 2914 return true; 2915 } 2916 2917 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2918 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2919 } 2920 2921 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2922 return young_list()->eden_used_bytes(); 2923 } 2924 2925 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2926 // must be equal to the humongous object limit. 2927 size_t G1CollectedHeap::max_tlab_size() const { 2928 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment); 2929 } 2930 2931 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2932 AllocationContext_t context = AllocationContext::current(); 2933 return _allocator->unsafe_max_tlab_alloc(context); 2934 } 2935 2936 size_t G1CollectedHeap::max_capacity() const { 2937 return _hrm.reserved().byte_size(); 2938 } 2939 2940 jlong G1CollectedHeap::millis_since_last_gc() { 2941 // assert(false, "NYI"); 2942 return 0; 2943 } 2944 2945 void G1CollectedHeap::prepare_for_verify() { 2946 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2947 ensure_parsability(false); 2948 } 2949 g1_rem_set()->prepare_for_verify(); 2950 } 2951 2952 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 2953 VerifyOption vo) { 2954 switch (vo) { 2955 case VerifyOption_G1UsePrevMarking: 2956 return hr->obj_allocated_since_prev_marking(obj); 2957 case VerifyOption_G1UseNextMarking: 2958 return hr->obj_allocated_since_next_marking(obj); 2959 case VerifyOption_G1UseMarkWord: 2960 return false; 2961 default: 2962 ShouldNotReachHere(); 2963 } 2964 return false; // keep some compilers happy 2965 } 2966 2967 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 2968 switch (vo) { 2969 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 2970 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 2971 case VerifyOption_G1UseMarkWord: return NULL; 2972 default: ShouldNotReachHere(); 2973 } 2974 return NULL; // keep some compilers happy 2975 } 2976 2977 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 2978 switch (vo) { 2979 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 2980 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 2981 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 2982 default: ShouldNotReachHere(); 2983 } 2984 return false; // keep some compilers happy 2985 } 2986 2987 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 2988 switch (vo) { 2989 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 2990 case VerifyOption_G1UseNextMarking: return "NTAMS"; 2991 case VerifyOption_G1UseMarkWord: return "NONE"; 2992 default: ShouldNotReachHere(); 2993 } 2994 return NULL; // keep some compilers happy 2995 } 2996 2997 class VerifyRootsClosure: public OopClosure { 2998 private: 2999 G1CollectedHeap* _g1h; 3000 VerifyOption _vo; 3001 bool _failures; 3002 public: 3003 // _vo == UsePrevMarking -> use "prev" marking information, 3004 // _vo == UseNextMarking -> use "next" marking information, 3005 // _vo == UseMarkWord -> use mark word from object header. 3006 VerifyRootsClosure(VerifyOption vo) : 3007 _g1h(G1CollectedHeap::heap()), 3008 _vo(vo), 3009 _failures(false) { } 3010 3011 bool failures() { return _failures; } 3012 3013 template <class T> void do_oop_nv(T* p) { 3014 T heap_oop = oopDesc::load_heap_oop(p); 3015 if (!oopDesc::is_null(heap_oop)) { 3016 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3017 if (_g1h->is_obj_dead_cond(obj, _vo)) { 3018 gclog_or_tty->print_cr("Root location " PTR_FORMAT " " 3019 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj)); 3020 if (_vo == VerifyOption_G1UseMarkWord) { 3021 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark()); 3022 } 3023 obj->print_on(gclog_or_tty); 3024 _failures = true; 3025 } 3026 } 3027 } 3028 3029 void do_oop(oop* p) { do_oop_nv(p); } 3030 void do_oop(narrowOop* p) { do_oop_nv(p); } 3031 }; 3032 3033 class G1VerifyCodeRootOopClosure: public OopClosure { 3034 G1CollectedHeap* _g1h; 3035 OopClosure* _root_cl; 3036 nmethod* _nm; 3037 VerifyOption _vo; 3038 bool _failures; 3039 3040 template <class T> void do_oop_work(T* p) { 3041 // First verify that this root is live 3042 _root_cl->do_oop(p); 3043 3044 if (!G1VerifyHeapRegionCodeRoots) { 3045 // We're not verifying the code roots attached to heap region. 3046 return; 3047 } 3048 3049 // Don't check the code roots during marking verification in a full GC 3050 if (_vo == VerifyOption_G1UseMarkWord) { 3051 return; 3052 } 3053 3054 // Now verify that the current nmethod (which contains p) is 3055 // in the code root list of the heap region containing the 3056 // object referenced by p. 3057 3058 T heap_oop = oopDesc::load_heap_oop(p); 3059 if (!oopDesc::is_null(heap_oop)) { 3060 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3061 3062 // Now fetch the region containing the object 3063 HeapRegion* hr = _g1h->heap_region_containing(obj); 3064 HeapRegionRemSet* hrrs = hr->rem_set(); 3065 // Verify that the strong code root list for this region 3066 // contains the nmethod 3067 if (!hrrs->strong_code_roots_list_contains(_nm)) { 3068 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " " 3069 "from nmethod " PTR_FORMAT " not in strong " 3070 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")", 3071 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end())); 3072 _failures = true; 3073 } 3074 } 3075 } 3076 3077 public: 3078 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 3079 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 3080 3081 void do_oop(oop* p) { do_oop_work(p); } 3082 void do_oop(narrowOop* p) { do_oop_work(p); } 3083 3084 void set_nmethod(nmethod* nm) { _nm = nm; } 3085 bool failures() { return _failures; } 3086 }; 3087 3088 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 3089 G1VerifyCodeRootOopClosure* _oop_cl; 3090 3091 public: 3092 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 3093 _oop_cl(oop_cl) {} 3094 3095 void do_code_blob(CodeBlob* cb) { 3096 nmethod* nm = cb->as_nmethod_or_null(); 3097 if (nm != NULL) { 3098 _oop_cl->set_nmethod(nm); 3099 nm->oops_do(_oop_cl); 3100 } 3101 } 3102 }; 3103 3104 class YoungRefCounterClosure : public OopClosure { 3105 G1CollectedHeap* _g1h; 3106 int _count; 3107 public: 3108 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 3109 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 3110 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 3111 3112 int count() { return _count; } 3113 void reset_count() { _count = 0; }; 3114 }; 3115 3116 class VerifyKlassClosure: public KlassClosure { 3117 YoungRefCounterClosure _young_ref_counter_closure; 3118 OopClosure *_oop_closure; 3119 public: 3120 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 3121 void do_klass(Klass* k) { 3122 k->oops_do(_oop_closure); 3123 3124 _young_ref_counter_closure.reset_count(); 3125 k->oops_do(&_young_ref_counter_closure); 3126 if (_young_ref_counter_closure.count() > 0) { 3127 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k))); 3128 } 3129 } 3130 }; 3131 3132 class VerifyLivenessOopClosure: public OopClosure { 3133 G1CollectedHeap* _g1h; 3134 VerifyOption _vo; 3135 public: 3136 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 3137 _g1h(g1h), _vo(vo) 3138 { } 3139 void do_oop(narrowOop *p) { do_oop_work(p); } 3140 void do_oop( oop *p) { do_oop_work(p); } 3141 3142 template <class T> void do_oop_work(T *p) { 3143 oop obj = oopDesc::load_decode_heap_oop(p); 3144 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 3145 "Dead object referenced by a not dead object"); 3146 } 3147 }; 3148 3149 class VerifyObjsInRegionClosure: public ObjectClosure { 3150 private: 3151 G1CollectedHeap* _g1h; 3152 size_t _live_bytes; 3153 HeapRegion *_hr; 3154 VerifyOption _vo; 3155 public: 3156 // _vo == UsePrevMarking -> use "prev" marking information, 3157 // _vo == UseNextMarking -> use "next" marking information, 3158 // _vo == UseMarkWord -> use mark word from object header. 3159 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 3160 : _live_bytes(0), _hr(hr), _vo(vo) { 3161 _g1h = G1CollectedHeap::heap(); 3162 } 3163 void do_object(oop o) { 3164 VerifyLivenessOopClosure isLive(_g1h, _vo); 3165 assert(o != NULL, "Huh?"); 3166 if (!_g1h->is_obj_dead_cond(o, _vo)) { 3167 // If the object is alive according to the mark word, 3168 // then verify that the marking information agrees. 3169 // Note we can't verify the contra-positive of the 3170 // above: if the object is dead (according to the mark 3171 // word), it may not be marked, or may have been marked 3172 // but has since became dead, or may have been allocated 3173 // since the last marking. 3174 if (_vo == VerifyOption_G1UseMarkWord) { 3175 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 3176 } 3177 3178 o->oop_iterate_no_header(&isLive); 3179 if (!_hr->obj_allocated_since_prev_marking(o)) { 3180 size_t obj_size = o->size(); // Make sure we don't overflow 3181 _live_bytes += (obj_size * HeapWordSize); 3182 } 3183 } 3184 } 3185 size_t live_bytes() { return _live_bytes; } 3186 }; 3187 3188 class VerifyArchiveOopClosure: public OopClosure { 3189 public: 3190 VerifyArchiveOopClosure(HeapRegion *hr) { } 3191 void do_oop(narrowOop *p) { do_oop_work(p); } 3192 void do_oop( oop *p) { do_oop_work(p); } 3193 3194 template <class T> void do_oop_work(T *p) { 3195 oop obj = oopDesc::load_decode_heap_oop(p); 3196 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj), 3197 err_msg("Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT, 3198 p2i(p), p2i(obj))); 3199 } 3200 }; 3201 3202 class VerifyArchiveRegionClosure: public ObjectClosure { 3203 public: 3204 VerifyArchiveRegionClosure(HeapRegion *hr) { } 3205 // Verify that all object pointers are to archive regions. 3206 void do_object(oop o) { 3207 VerifyArchiveOopClosure checkOop(NULL); 3208 assert(o != NULL, "Should not be here for NULL oops"); 3209 o->oop_iterate_no_header(&checkOop); 3210 } 3211 }; 3212 3213 class VerifyRegionClosure: public HeapRegionClosure { 3214 private: 3215 bool _par; 3216 VerifyOption _vo; 3217 bool _failures; 3218 public: 3219 // _vo == UsePrevMarking -> use "prev" marking information, 3220 // _vo == UseNextMarking -> use "next" marking information, 3221 // _vo == UseMarkWord -> use mark word from object header. 3222 VerifyRegionClosure(bool par, VerifyOption vo) 3223 : _par(par), 3224 _vo(vo), 3225 _failures(false) {} 3226 3227 bool failures() { 3228 return _failures; 3229 } 3230 3231 bool doHeapRegion(HeapRegion* r) { 3232 // For archive regions, verify there are no heap pointers to 3233 // non-pinned regions. For all others, verify liveness info. 3234 if (r->is_archive()) { 3235 VerifyArchiveRegionClosure verify_oop_pointers(r); 3236 r->object_iterate(&verify_oop_pointers); 3237 return true; 3238 } 3239 if (!r->is_continues_humongous()) { 3240 bool failures = false; 3241 r->verify(_vo, &failures); 3242 if (failures) { 3243 _failures = true; 3244 } else { 3245 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3246 r->object_iterate(¬_dead_yet_cl); 3247 if (_vo != VerifyOption_G1UseNextMarking) { 3248 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3249 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] " 3250 "max_live_bytes " SIZE_FORMAT " " 3251 "< calculated " SIZE_FORMAT, 3252 p2i(r->bottom()), p2i(r->end()), 3253 r->max_live_bytes(), 3254 not_dead_yet_cl.live_bytes()); 3255 _failures = true; 3256 } 3257 } else { 3258 // When vo == UseNextMarking we cannot currently do a sanity 3259 // check on the live bytes as the calculation has not been 3260 // finalized yet. 3261 } 3262 } 3263 } 3264 return false; // stop the region iteration if we hit a failure 3265 } 3266 }; 3267 3268 // This is the task used for parallel verification of the heap regions 3269 3270 class G1ParVerifyTask: public AbstractGangTask { 3271 private: 3272 G1CollectedHeap* _g1h; 3273 VerifyOption _vo; 3274 bool _failures; 3275 HeapRegionClaimer _hrclaimer; 3276 3277 public: 3278 // _vo == UsePrevMarking -> use "prev" marking information, 3279 // _vo == UseNextMarking -> use "next" marking information, 3280 // _vo == UseMarkWord -> use mark word from object header. 3281 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3282 AbstractGangTask("Parallel verify task"), 3283 _g1h(g1h), 3284 _vo(vo), 3285 _failures(false), 3286 _hrclaimer(g1h->workers()->active_workers()) {} 3287 3288 bool failures() { 3289 return _failures; 3290 } 3291 3292 void work(uint worker_id) { 3293 HandleMark hm; 3294 VerifyRegionClosure blk(true, _vo); 3295 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer); 3296 if (blk.failures()) { 3297 _failures = true; 3298 } 3299 } 3300 }; 3301 3302 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3303 if (SafepointSynchronize::is_at_safepoint()) { 3304 assert(Thread::current()->is_VM_thread(), 3305 "Expected to be executed serially by the VM thread at this point"); 3306 3307 if (!silent) { gclog_or_tty->print("Roots "); } 3308 VerifyRootsClosure rootsCl(vo); 3309 VerifyKlassClosure klassCl(this, &rootsCl); 3310 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3311 3312 // We apply the relevant closures to all the oops in the 3313 // system dictionary, class loader data graph, the string table 3314 // and the nmethods in the code cache. 3315 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3316 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3317 3318 { 3319 G1RootProcessor root_processor(this, 1); 3320 root_processor.process_all_roots(&rootsCl, 3321 &cldCl, 3322 &blobsCl); 3323 } 3324 3325 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3326 3327 if (vo != VerifyOption_G1UseMarkWord) { 3328 // If we're verifying during a full GC then the region sets 3329 // will have been torn down at the start of the GC. Therefore 3330 // verifying the region sets will fail. So we only verify 3331 // the region sets when not in a full GC. 3332 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3333 verify_region_sets(); 3334 } 3335 3336 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3337 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3338 3339 G1ParVerifyTask task(this, vo); 3340 workers()->run_task(&task); 3341 if (task.failures()) { 3342 failures = true; 3343 } 3344 3345 } else { 3346 VerifyRegionClosure blk(false, vo); 3347 heap_region_iterate(&blk); 3348 if (blk.failures()) { 3349 failures = true; 3350 } 3351 } 3352 3353 if (G1StringDedup::is_enabled()) { 3354 if (!silent) gclog_or_tty->print("StrDedup "); 3355 G1StringDedup::verify(); 3356 } 3357 3358 if (failures) { 3359 gclog_or_tty->print_cr("Heap:"); 3360 // It helps to have the per-region information in the output to 3361 // help us track down what went wrong. This is why we call 3362 // print_extended_on() instead of print_on(). 3363 print_extended_on(gclog_or_tty); 3364 gclog_or_tty->cr(); 3365 gclog_or_tty->flush(); 3366 } 3367 guarantee(!failures, "there should not have been any failures"); 3368 } else { 3369 if (!silent) { 3370 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3371 if (G1StringDedup::is_enabled()) { 3372 gclog_or_tty->print(", StrDedup"); 3373 } 3374 gclog_or_tty->print(") "); 3375 } 3376 } 3377 } 3378 3379 void G1CollectedHeap::verify(bool silent) { 3380 verify(silent, VerifyOption_G1UsePrevMarking); 3381 } 3382 3383 double G1CollectedHeap::verify(bool guard, const char* msg) { 3384 double verify_time_ms = 0.0; 3385 3386 if (guard && total_collections() >= VerifyGCStartAt) { 3387 double verify_start = os::elapsedTime(); 3388 HandleMark hm; // Discard invalid handles created during verification 3389 prepare_for_verify(); 3390 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3391 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3392 } 3393 3394 return verify_time_ms; 3395 } 3396 3397 void G1CollectedHeap::verify_before_gc() { 3398 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3399 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3400 } 3401 3402 void G1CollectedHeap::verify_after_gc() { 3403 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3404 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3405 } 3406 3407 class PrintRegionClosure: public HeapRegionClosure { 3408 outputStream* _st; 3409 public: 3410 PrintRegionClosure(outputStream* st) : _st(st) {} 3411 bool doHeapRegion(HeapRegion* r) { 3412 r->print_on(_st); 3413 return false; 3414 } 3415 }; 3416 3417 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3418 const HeapRegion* hr, 3419 const VerifyOption vo) const { 3420 switch (vo) { 3421 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3422 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3423 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive(); 3424 default: ShouldNotReachHere(); 3425 } 3426 return false; // keep some compilers happy 3427 } 3428 3429 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3430 const VerifyOption vo) const { 3431 switch (vo) { 3432 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3433 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3434 case VerifyOption_G1UseMarkWord: { 3435 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj); 3436 return !obj->is_gc_marked() && !hr->is_archive(); 3437 } 3438 default: ShouldNotReachHere(); 3439 } 3440 return false; // keep some compilers happy 3441 } 3442 3443 void G1CollectedHeap::print_on(outputStream* st) const { 3444 st->print(" %-20s", "garbage-first heap"); 3445 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3446 capacity()/K, used_unlocked()/K); 3447 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")", 3448 p2i(_hrm.reserved().start()), 3449 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords), 3450 p2i(_hrm.reserved().end())); 3451 st->cr(); 3452 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3453 uint young_regions = _young_list->length(); 3454 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3455 (size_t) young_regions * HeapRegion::GrainBytes / K); 3456 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3457 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3458 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3459 st->cr(); 3460 MetaspaceAux::print_on(st); 3461 } 3462 3463 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3464 print_on(st); 3465 3466 // Print the per-region information. 3467 st->cr(); 3468 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, " 3469 "HS=humongous(starts), HC=humongous(continues), " 3470 "CS=collection set, F=free, A=archive, TS=gc time stamp, " 3471 "PTAMS=previous top-at-mark-start, " 3472 "NTAMS=next top-at-mark-start)"); 3473 PrintRegionClosure blk(st); 3474 heap_region_iterate(&blk); 3475 } 3476 3477 void G1CollectedHeap::print_on_error(outputStream* st) const { 3478 this->CollectedHeap::print_on_error(st); 3479 3480 if (_cm != NULL) { 3481 st->cr(); 3482 _cm->print_on_error(st); 3483 } 3484 } 3485 3486 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3487 workers()->print_worker_threads_on(st); 3488 _cmThread->print_on(st); 3489 st->cr(); 3490 _cm->print_worker_threads_on(st); 3491 _cg1r->print_worker_threads_on(st); 3492 if (G1StringDedup::is_enabled()) { 3493 G1StringDedup::print_worker_threads_on(st); 3494 } 3495 } 3496 3497 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3498 workers()->threads_do(tc); 3499 tc->do_thread(_cmThread); 3500 _cg1r->threads_do(tc); 3501 if (G1StringDedup::is_enabled()) { 3502 G1StringDedup::threads_do(tc); 3503 } 3504 } 3505 3506 void G1CollectedHeap::print_tracing_info() const { 3507 // We'll overload this to mean "trace GC pause statistics." 3508 if (TraceYoungGenTime || TraceOldGenTime) { 3509 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3510 // to that. 3511 g1_policy()->print_tracing_info(); 3512 } 3513 if (G1SummarizeRSetStats) { 3514 g1_rem_set()->print_summary_info(); 3515 } 3516 if (G1SummarizeConcMark) { 3517 concurrent_mark()->print_summary_info(); 3518 } 3519 g1_policy()->print_yg_surv_rate_info(); 3520 } 3521 3522 #ifndef PRODUCT 3523 // Helpful for debugging RSet issues. 3524 3525 class PrintRSetsClosure : public HeapRegionClosure { 3526 private: 3527 const char* _msg; 3528 size_t _occupied_sum; 3529 3530 public: 3531 bool doHeapRegion(HeapRegion* r) { 3532 HeapRegionRemSet* hrrs = r->rem_set(); 3533 size_t occupied = hrrs->occupied(); 3534 _occupied_sum += occupied; 3535 3536 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT, 3537 HR_FORMAT_PARAMS(r)); 3538 if (occupied == 0) { 3539 gclog_or_tty->print_cr(" RSet is empty"); 3540 } else { 3541 hrrs->print(); 3542 } 3543 gclog_or_tty->print_cr("----------"); 3544 return false; 3545 } 3546 3547 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3548 gclog_or_tty->cr(); 3549 gclog_or_tty->print_cr("========================================"); 3550 gclog_or_tty->print_cr("%s", msg); 3551 gclog_or_tty->cr(); 3552 } 3553 3554 ~PrintRSetsClosure() { 3555 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 3556 gclog_or_tty->print_cr("========================================"); 3557 gclog_or_tty->cr(); 3558 } 3559 }; 3560 3561 void G1CollectedHeap::print_cset_rsets() { 3562 PrintRSetsClosure cl("Printing CSet RSets"); 3563 collection_set_iterate(&cl); 3564 } 3565 3566 void G1CollectedHeap::print_all_rsets() { 3567 PrintRSetsClosure cl("Printing All RSets");; 3568 heap_region_iterate(&cl); 3569 } 3570 #endif // PRODUCT 3571 3572 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 3573 YoungList* young_list = heap()->young_list(); 3574 3575 size_t eden_used_bytes = young_list->eden_used_bytes(); 3576 size_t survivor_used_bytes = young_list->survivor_used_bytes(); 3577 3578 size_t eden_capacity_bytes = 3579 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 3580 3581 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 3582 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes); 3583 } 3584 3585 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 3586 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 3587 stats->unused(), stats->used(), stats->region_end_waste(), 3588 stats->regions_filled(), stats->direct_allocated(), 3589 stats->failure_used(), stats->failure_waste()); 3590 } 3591 3592 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 3593 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 3594 gc_tracer->report_gc_heap_summary(when, heap_summary); 3595 3596 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 3597 gc_tracer->report_metaspace_summary(when, metaspace_summary); 3598 } 3599 3600 3601 G1CollectedHeap* G1CollectedHeap::heap() { 3602 CollectedHeap* heap = Universe::heap(); 3603 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 3604 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); 3605 return (G1CollectedHeap*)heap; 3606 } 3607 3608 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3609 // always_do_update_barrier = false; 3610 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3611 // Fill TLAB's and such 3612 accumulate_statistics_all_tlabs(); 3613 ensure_parsability(true); 3614 3615 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3616 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3617 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3618 } 3619 } 3620 3621 void G1CollectedHeap::gc_epilogue(bool full) { 3622 3623 if (G1SummarizeRSetStats && 3624 (G1SummarizeRSetStatsPeriod > 0) && 3625 // we are at the end of the GC. Total collections has already been increased. 3626 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3627 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3628 } 3629 3630 // FIXME: what is this about? 3631 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3632 // is set. 3633 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3634 "derived pointer present")); 3635 // always_do_update_barrier = true; 3636 3637 resize_all_tlabs(); 3638 allocation_context_stats().update(full); 3639 3640 // We have just completed a GC. Update the soft reference 3641 // policy with the new heap occupancy 3642 Universe::update_heap_info_at_gc(); 3643 } 3644 3645 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3646 uint gc_count_before, 3647 bool* succeeded, 3648 GCCause::Cause gc_cause) { 3649 assert_heap_not_locked_and_not_at_safepoint(); 3650 g1_policy()->record_stop_world_start(); 3651 VM_G1IncCollectionPause op(gc_count_before, 3652 word_size, 3653 false, /* should_initiate_conc_mark */ 3654 g1_policy()->max_pause_time_ms(), 3655 gc_cause); 3656 3657 op.set_allocation_context(AllocationContext::current()); 3658 VMThread::execute(&op); 3659 3660 HeapWord* result = op.result(); 3661 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3662 assert(result == NULL || ret_succeeded, 3663 "the result should be NULL if the VM did not succeed"); 3664 *succeeded = ret_succeeded; 3665 3666 assert_heap_not_locked(); 3667 return result; 3668 } 3669 3670 void 3671 G1CollectedHeap::doConcurrentMark() { 3672 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3673 if (!_cmThread->in_progress()) { 3674 _cmThread->set_started(); 3675 CGC_lock->notify(); 3676 } 3677 } 3678 3679 size_t G1CollectedHeap::pending_card_num() { 3680 size_t extra_cards = 0; 3681 JavaThread *curr = Threads::first(); 3682 while (curr != NULL) { 3683 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3684 extra_cards += dcq.size(); 3685 curr = curr->next(); 3686 } 3687 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3688 size_t buffer_size = dcqs.buffer_size(); 3689 size_t buffer_num = dcqs.completed_buffers_num(); 3690 3691 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3692 // in bytes - not the number of 'entries'. We need to convert 3693 // into a number of cards. 3694 return (buffer_size * buffer_num + extra_cards) / oopSize; 3695 } 3696 3697 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3698 private: 3699 size_t _total_humongous; 3700 size_t _candidate_humongous; 3701 3702 DirtyCardQueue _dcq; 3703 3704 // We don't nominate objects with many remembered set entries, on 3705 // the assumption that such objects are likely still live. 3706 bool is_remset_small(HeapRegion* region) const { 3707 HeapRegionRemSet* const rset = region->rem_set(); 3708 return G1EagerReclaimHumongousObjectsWithStaleRefs 3709 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) 3710 : rset->is_empty(); 3711 } 3712 3713 bool is_typeArray_region(HeapRegion* region) const { 3714 return oop(region->bottom())->is_typeArray(); 3715 } 3716 3717 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { 3718 assert(region->is_starts_humongous(), "Must start a humongous object"); 3719 3720 // Candidate selection must satisfy the following constraints 3721 // while concurrent marking is in progress: 3722 // 3723 // * In order to maintain SATB invariants, an object must not be 3724 // reclaimed if it was allocated before the start of marking and 3725 // has not had its references scanned. Such an object must have 3726 // its references (including type metadata) scanned to ensure no 3727 // live objects are missed by the marking process. Objects 3728 // allocated after the start of concurrent marking don't need to 3729 // be scanned. 3730 // 3731 // * An object must not be reclaimed if it is on the concurrent 3732 // mark stack. Objects allocated after the start of concurrent 3733 // marking are never pushed on the mark stack. 3734 // 3735 // Nominating only objects allocated after the start of concurrent 3736 // marking is sufficient to meet both constraints. This may miss 3737 // some objects that satisfy the constraints, but the marking data 3738 // structures don't support efficiently performing the needed 3739 // additional tests or scrubbing of the mark stack. 3740 // 3741 // However, we presently only nominate is_typeArray() objects. 3742 // A humongous object containing references induces remembered 3743 // set entries on other regions. In order to reclaim such an 3744 // object, those remembered sets would need to be cleaned up. 3745 // 3746 // We also treat is_typeArray() objects specially, allowing them 3747 // to be reclaimed even if allocated before the start of 3748 // concurrent mark. For this we rely on mark stack insertion to 3749 // exclude is_typeArray() objects, preventing reclaiming an object 3750 // that is in the mark stack. We also rely on the metadata for 3751 // such objects to be built-in and so ensured to be kept live. 3752 // Frequent allocation and drop of large binary blobs is an 3753 // important use case for eager reclaim, and this special handling 3754 // may reduce needed headroom. 3755 3756 return is_typeArray_region(region) && is_remset_small(region); 3757 } 3758 3759 public: 3760 RegisterHumongousWithInCSetFastTestClosure() 3761 : _total_humongous(0), 3762 _candidate_humongous(0), 3763 _dcq(&JavaThread::dirty_card_queue_set()) { 3764 } 3765 3766 virtual bool doHeapRegion(HeapRegion* r) { 3767 if (!r->is_starts_humongous()) { 3768 return false; 3769 } 3770 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3771 3772 bool is_candidate = humongous_region_is_candidate(g1h, r); 3773 uint rindex = r->hrm_index(); 3774 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 3775 if (is_candidate) { 3776 _candidate_humongous++; 3777 g1h->register_humongous_region_with_cset(rindex); 3778 // Is_candidate already filters out humongous object with large remembered sets. 3779 // If we have a humongous object with a few remembered sets, we simply flush these 3780 // remembered set entries into the DCQS. That will result in automatic 3781 // re-evaluation of their remembered set entries during the following evacuation 3782 // phase. 3783 if (!r->rem_set()->is_empty()) { 3784 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 3785 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 3786 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 3787 HeapRegionRemSetIterator hrrs(r->rem_set()); 3788 size_t card_index; 3789 while (hrrs.has_next(card_index)) { 3790 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 3791 // The remembered set might contain references to already freed 3792 // regions. Filter out such entries to avoid failing card table 3793 // verification. 3794 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) { 3795 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 3796 *card_ptr = CardTableModRefBS::dirty_card_val(); 3797 _dcq.enqueue(card_ptr); 3798 } 3799 } 3800 } 3801 r->rem_set()->clear_locked(); 3802 } 3803 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 3804 } 3805 _total_humongous++; 3806 3807 return false; 3808 } 3809 3810 size_t total_humongous() const { return _total_humongous; } 3811 size_t candidate_humongous() const { return _candidate_humongous; } 3812 3813 void flush_rem_set_entries() { _dcq.flush(); } 3814 }; 3815 3816 void G1CollectedHeap::register_humongous_regions_with_cset() { 3817 if (!G1EagerReclaimHumongousObjects) { 3818 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 3819 return; 3820 } 3821 double time = os::elapsed_counter(); 3822 3823 // Collect reclaim candidate information and register candidates with cset. 3824 RegisterHumongousWithInCSetFastTestClosure cl; 3825 heap_region_iterate(&cl); 3826 3827 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 3828 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 3829 cl.total_humongous(), 3830 cl.candidate_humongous()); 3831 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3832 3833 // Finally flush all remembered set entries to re-check into the global DCQS. 3834 cl.flush_rem_set_entries(); 3835 } 3836 3837 #ifdef ASSERT 3838 class VerifyCSetClosure: public HeapRegionClosure { 3839 public: 3840 bool doHeapRegion(HeapRegion* hr) { 3841 // Here we check that the CSet region's RSet is ready for parallel 3842 // iteration. The fields that we'll verify are only manipulated 3843 // when the region is part of a CSet and is collected. Afterwards, 3844 // we reset these fields when we clear the region's RSet (when the 3845 // region is freed) so they are ready when the region is 3846 // re-allocated. The only exception to this is if there's an 3847 // evacuation failure and instead of freeing the region we leave 3848 // it in the heap. In that case, we reset these fields during 3849 // evacuation failure handling. 3850 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3851 3852 // Here's a good place to add any other checks we'd like to 3853 // perform on CSet regions. 3854 return false; 3855 } 3856 }; 3857 #endif // ASSERT 3858 3859 uint G1CollectedHeap::num_task_queues() const { 3860 return _task_queues->size(); 3861 } 3862 3863 #if TASKQUEUE_STATS 3864 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3865 st->print_raw_cr("GC Task Stats"); 3866 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3867 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3868 } 3869 3870 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3871 print_taskqueue_stats_hdr(st); 3872 3873 TaskQueueStats totals; 3874 const uint n = num_task_queues(); 3875 for (uint i = 0; i < n; ++i) { 3876 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 3877 totals += task_queue(i)->stats; 3878 } 3879 st->print_raw("tot "); totals.print(st); st->cr(); 3880 3881 DEBUG_ONLY(totals.verify()); 3882 } 3883 3884 void G1CollectedHeap::reset_taskqueue_stats() { 3885 const uint n = num_task_queues(); 3886 for (uint i = 0; i < n; ++i) { 3887 task_queue(i)->stats.reset(); 3888 } 3889 } 3890 #endif // TASKQUEUE_STATS 3891 3892 void G1CollectedHeap::log_gc_header() { 3893 if (!G1Log::fine()) { 3894 return; 3895 } 3896 3897 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id()); 3898 3899 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3900 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)") 3901 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3902 3903 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3904 } 3905 3906 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3907 if (!G1Log::fine()) { 3908 return; 3909 } 3910 3911 if (G1Log::finer()) { 3912 if (evacuation_failed()) { 3913 gclog_or_tty->print(" (to-space exhausted)"); 3914 } 3915 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3916 g1_policy()->phase_times()->note_gc_end(); 3917 g1_policy()->phase_times()->print(pause_time_sec); 3918 g1_policy()->print_detailed_heap_transition(); 3919 } else { 3920 if (evacuation_failed()) { 3921 gclog_or_tty->print("--"); 3922 } 3923 g1_policy()->print_heap_transition(); 3924 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3925 } 3926 gclog_or_tty->flush(); 3927 } 3928 3929 void G1CollectedHeap::wait_for_root_region_scanning() { 3930 double scan_wait_start = os::elapsedTime(); 3931 // We have to wait until the CM threads finish scanning the 3932 // root regions as it's the only way to ensure that all the 3933 // objects on them have been correctly scanned before we start 3934 // moving them during the GC. 3935 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3936 double wait_time_ms = 0.0; 3937 if (waited) { 3938 double scan_wait_end = os::elapsedTime(); 3939 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3940 } 3941 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3942 } 3943 3944 bool 3945 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3946 assert_at_safepoint(true /* should_be_vm_thread */); 3947 guarantee(!is_gc_active(), "collection is not reentrant"); 3948 3949 if (GC_locker::check_active_before_gc()) { 3950 return false; 3951 } 3952 3953 _gc_timer_stw->register_gc_start(); 3954 3955 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3956 3957 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3958 ResourceMark rm; 3959 3960 wait_for_root_region_scanning(); 3961 3962 G1Log::update_level(); 3963 print_heap_before_gc(); 3964 trace_heap_before_gc(_gc_tracer_stw); 3965 3966 verify_region_sets_optional(); 3967 verify_dirty_young_regions(); 3968 3969 // This call will decide whether this pause is an initial-mark 3970 // pause. If it is, during_initial_mark_pause() will return true 3971 // for the duration of this pause. 3972 g1_policy()->decide_on_conc_mark_initiation(); 3973 3974 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3975 assert(!collector_state()->during_initial_mark_pause() || 3976 collector_state()->gcs_are_young(), "sanity"); 3977 3978 // We also do not allow mixed GCs during marking. 3979 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity"); 3980 3981 // Record whether this pause is an initial mark. When the current 3982 // thread has completed its logging output and it's safe to signal 3983 // the CM thread, the flag's value in the policy has been reset. 3984 bool should_start_conc_mark = collector_state()->during_initial_mark_pause(); 3985 3986 // Inner scope for scope based logging, timers, and stats collection 3987 { 3988 EvacuationInfo evacuation_info; 3989 3990 if (collector_state()->during_initial_mark_pause()) { 3991 // We are about to start a marking cycle, so we increment the 3992 // full collection counter. 3993 increment_old_marking_cycles_started(); 3994 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3995 } 3996 3997 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 3998 3999 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 4000 4001 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 4002 workers()->active_workers(), 4003 Threads::number_of_non_daemon_threads()); 4004 workers()->set_active_workers(active_workers); 4005 4006 double pause_start_sec = os::elapsedTime(); 4007 g1_policy()->phase_times()->note_gc_start(active_workers, collector_state()->mark_in_progress()); 4008 log_gc_header(); 4009 4010 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 4011 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 4012 4013 // If the secondary_free_list is not empty, append it to the 4014 // free_list. No need to wait for the cleanup operation to finish; 4015 // the region allocation code will check the secondary_free_list 4016 // and wait if necessary. If the G1StressConcRegionFreeing flag is 4017 // set, skip this step so that the region allocation code has to 4018 // get entries from the secondary_free_list. 4019 if (!G1StressConcRegionFreeing) { 4020 append_secondary_free_list_if_not_empty_with_lock(); 4021 } 4022 4023 assert(check_young_list_well_formed(), "young list should be well formed"); 4024 4025 // Don't dynamically change the number of GC threads this early. A value of 4026 // 0 is used to indicate serial work. When parallel work is done, 4027 // it will be set. 4028 4029 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 4030 IsGCActiveMark x; 4031 4032 gc_prologue(false); 4033 increment_total_collections(false /* full gc */); 4034 increment_gc_time_stamp(); 4035 4036 verify_before_gc(); 4037 4038 check_bitmaps("GC Start"); 4039 4040 COMPILER2_PRESENT(DerivedPointerTable::clear()); 4041 4042 // Please see comment in g1CollectedHeap.hpp and 4043 // G1CollectedHeap::ref_processing_init() to see how 4044 // reference processing currently works in G1. 4045 4046 // Enable discovery in the STW reference processor 4047 ref_processor_stw()->enable_discovery(); 4048 4049 { 4050 // We want to temporarily turn off discovery by the 4051 // CM ref processor, if necessary, and turn it back on 4052 // on again later if we do. Using a scoped 4053 // NoRefDiscovery object will do this. 4054 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 4055 4056 // Forget the current alloc region (we might even choose it to be part 4057 // of the collection set!). 4058 _allocator->release_mutator_alloc_region(); 4059 4060 // We should call this after we retire the mutator alloc 4061 // region(s) so that all the ALLOC / RETIRE events are generated 4062 // before the start GC event. 4063 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 4064 4065 // This timing is only used by the ergonomics to handle our pause target. 4066 // It is unclear why this should not include the full pause. We will 4067 // investigate this in CR 7178365. 4068 // 4069 // Preserving the old comment here if that helps the investigation: 4070 // 4071 // The elapsed time induced by the start time below deliberately elides 4072 // the possible verification above. 4073 double sample_start_time_sec = os::elapsedTime(); 4074 4075 g1_policy()->record_collection_pause_start(sample_start_time_sec); 4076 4077 if (collector_state()->during_initial_mark_pause()) { 4078 concurrent_mark()->checkpointRootsInitialPre(); 4079 } 4080 4081 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms); 4082 g1_policy()->finalize_old_cset_part(time_remaining_ms); 4083 4084 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length()); 4085 4086 register_humongous_regions_with_cset(); 4087 4088 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table."); 4089 4090 _cm->note_start_of_gc(); 4091 // We call this after finalize_cset() to 4092 // ensure that the CSet has been finalized. 4093 _cm->verify_no_cset_oops(); 4094 4095 if (_hr_printer.is_active()) { 4096 HeapRegion* hr = g1_policy()->collection_set(); 4097 while (hr != NULL) { 4098 _hr_printer.cset(hr); 4099 hr = hr->next_in_collection_set(); 4100 } 4101 } 4102 4103 #ifdef ASSERT 4104 VerifyCSetClosure cl; 4105 collection_set_iterate(&cl); 4106 #endif // ASSERT 4107 4108 // Initialize the GC alloc regions. 4109 _allocator->init_gc_alloc_regions(evacuation_info); 4110 4111 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length()); 4112 // Actually do the work... 4113 evacuate_collection_set(evacuation_info, &per_thread_states); 4114 4115 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 4116 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words); 4117 4118 eagerly_reclaim_humongous_regions(); 4119 4120 g1_policy()->clear_collection_set(); 4121 4122 // Start a new incremental collection set for the next pause. 4123 g1_policy()->start_incremental_cset_building(); 4124 4125 clear_cset_fast_test(); 4126 4127 _young_list->reset_sampled_info(); 4128 4129 // Don't check the whole heap at this point as the 4130 // GC alloc regions from this pause have been tagged 4131 // as survivors and moved on to the survivor list. 4132 // Survivor regions will fail the !is_young() check. 4133 assert(check_young_list_empty(false /* check_heap */), 4134 "young list should be empty"); 4135 4136 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 4137 _young_list->first_survivor_region(), 4138 _young_list->last_survivor_region()); 4139 4140 _young_list->reset_auxilary_lists(); 4141 4142 if (evacuation_failed()) { 4143 set_used(recalculate_used()); 4144 if (_archive_allocator != NULL) { 4145 _archive_allocator->clear_used(); 4146 } 4147 for (uint i = 0; i < ParallelGCThreads; i++) { 4148 if (_evacuation_failed_info_array[i].has_failed()) { 4149 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 4150 } 4151 } 4152 } else { 4153 // The "used" of the the collection set have already been subtracted 4154 // when they were freed. Add in the bytes evacuated. 4155 increase_used(g1_policy()->bytes_copied_during_gc()); 4156 } 4157 4158 if (collector_state()->during_initial_mark_pause()) { 4159 // We have to do this before we notify the CM threads that 4160 // they can start working to make sure that all the 4161 // appropriate initialization is done on the CM object. 4162 concurrent_mark()->checkpointRootsInitialPost(); 4163 collector_state()->set_mark_in_progress(true); 4164 // Note that we don't actually trigger the CM thread at 4165 // this point. We do that later when we're sure that 4166 // the current thread has completed its logging output. 4167 } 4168 4169 allocate_dummy_regions(); 4170 4171 _allocator->init_mutator_alloc_region(); 4172 4173 { 4174 size_t expand_bytes = g1_policy()->expansion_amount(); 4175 if (expand_bytes > 0) { 4176 size_t bytes_before = capacity(); 4177 // No need for an ergo verbose message here, 4178 // expansion_amount() does this when it returns a value > 0. 4179 if (!expand(expand_bytes)) { 4180 // We failed to expand the heap. Cannot do anything about it. 4181 } 4182 } 4183 } 4184 4185 // We redo the verification but now wrt to the new CSet which 4186 // has just got initialized after the previous CSet was freed. 4187 _cm->verify_no_cset_oops(); 4188 _cm->note_end_of_gc(); 4189 4190 // This timing is only used by the ergonomics to handle our pause target. 4191 // It is unclear why this should not include the full pause. We will 4192 // investigate this in CR 7178365. 4193 double sample_end_time_sec = os::elapsedTime(); 4194 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 4195 size_t total_cards_scanned = per_thread_states.total_cards_scanned(); 4196 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned); 4197 4198 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before()); 4199 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 4200 4201 MemoryService::track_memory_usage(); 4202 4203 // In prepare_for_verify() below we'll need to scan the deferred 4204 // update buffers to bring the RSets up-to-date if 4205 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4206 // the update buffers we'll probably need to scan cards on the 4207 // regions we just allocated to (i.e., the GC alloc 4208 // regions). However, during the last GC we called 4209 // set_saved_mark() on all the GC alloc regions, so card 4210 // scanning might skip the [saved_mark_word()...top()] area of 4211 // those regions (i.e., the area we allocated objects into 4212 // during the last GC). But it shouldn't. Given that 4213 // saved_mark_word() is conditional on whether the GC time stamp 4214 // on the region is current or not, by incrementing the GC time 4215 // stamp here we invalidate all the GC time stamps on all the 4216 // regions and saved_mark_word() will simply return top() for 4217 // all the regions. This is a nicer way of ensuring this rather 4218 // than iterating over the regions and fixing them. In fact, the 4219 // GC time stamp increment here also ensures that 4220 // saved_mark_word() will return top() between pauses, i.e., 4221 // during concurrent refinement. So we don't need the 4222 // is_gc_active() check to decided which top to use when 4223 // scanning cards (see CR 7039627). 4224 increment_gc_time_stamp(); 4225 4226 verify_after_gc(); 4227 check_bitmaps("GC End"); 4228 4229 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4230 ref_processor_stw()->verify_no_references_recorded(); 4231 4232 // CM reference discovery will be re-enabled if necessary. 4233 } 4234 4235 // We should do this after we potentially expand the heap so 4236 // that all the COMMIT events are generated before the end GC 4237 // event, and after we retire the GC alloc regions so that all 4238 // RETIRE events are generated before the end GC event. 4239 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4240 4241 #ifdef TRACESPINNING 4242 ParallelTaskTerminator::print_termination_counts(); 4243 #endif 4244 4245 gc_epilogue(false); 4246 } 4247 4248 // Print the remainder of the GC log output. 4249 log_gc_footer(os::elapsedTime() - pause_start_sec); 4250 4251 // It is not yet to safe to tell the concurrent mark to 4252 // start as we have some optional output below. We don't want the 4253 // output from the concurrent mark thread interfering with this 4254 // logging output either. 4255 4256 _hrm.verify_optional(); 4257 verify_region_sets_optional(); 4258 4259 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats()); 4260 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4261 4262 print_heap_after_gc(); 4263 trace_heap_after_gc(_gc_tracer_stw); 4264 4265 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4266 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4267 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4268 // before any GC notifications are raised. 4269 g1mm()->update_sizes(); 4270 4271 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4272 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4273 _gc_timer_stw->register_gc_end(); 4274 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4275 } 4276 // It should now be safe to tell the concurrent mark thread to start 4277 // without its logging output interfering with the logging output 4278 // that came from the pause. 4279 4280 if (should_start_conc_mark) { 4281 // CAUTION: after the doConcurrentMark() call below, 4282 // the concurrent marking thread(s) could be running 4283 // concurrently with us. Make sure that anything after 4284 // this point does not assume that we are the only GC thread 4285 // running. Note: of course, the actual marking work will 4286 // not start until the safepoint itself is released in 4287 // SuspendibleThreadSet::desynchronize(). 4288 doConcurrentMark(); 4289 } 4290 4291 return true; 4292 } 4293 4294 void G1CollectedHeap::remove_self_forwarding_pointers() { 4295 double remove_self_forwards_start = os::elapsedTime(); 4296 4297 G1ParRemoveSelfForwardPtrsTask rsfp_task; 4298 workers()->run_task(&rsfp_task); 4299 4300 // Now restore saved marks, if any. 4301 for (uint i = 0; i < ParallelGCThreads; i++) { 4302 OopAndMarkOopStack& cur = _preserved_objs[i]; 4303 while (!cur.is_empty()) { 4304 OopAndMarkOop elem = cur.pop(); 4305 elem.set_mark(); 4306 } 4307 cur.clear(true); 4308 } 4309 4310 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4311 } 4312 4313 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 4314 if (!_evacuation_failed) { 4315 _evacuation_failed = true; 4316 } 4317 4318 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 4319 4320 // We want to call the "for_promotion_failure" version only in the 4321 // case of a promotion failure. 4322 if (m->must_be_preserved_for_promotion_failure(obj)) { 4323 OopAndMarkOop elem(obj, m); 4324 _preserved_objs[worker_id].push(elem); 4325 } 4326 } 4327 4328 void G1ParCopyHelper::mark_object(oop obj) { 4329 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); 4330 4331 // We know that the object is not moving so it's safe to read its size. 4332 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4333 } 4334 4335 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4336 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4337 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4338 assert(from_obj != to_obj, "should not be self-forwarded"); 4339 4340 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); 4341 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); 4342 4343 // The object might be in the process of being copied by another 4344 // worker so we cannot trust that its to-space image is 4345 // well-formed. So we have to read its size from its from-space 4346 // image which we know should not be changing. 4347 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4348 } 4349 4350 template <class T> 4351 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4352 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4353 _scanned_klass->record_modified_oops(); 4354 } 4355 } 4356 4357 template <G1Barrier barrier, G1Mark do_mark_object> 4358 template <class T> 4359 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4360 T heap_oop = oopDesc::load_heap_oop(p); 4361 4362 if (oopDesc::is_null(heap_oop)) { 4363 return; 4364 } 4365 4366 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4367 4368 assert(_worker_id == _par_scan_state->worker_id(), "sanity"); 4369 4370 const InCSetState state = _g1->in_cset_state(obj); 4371 if (state.is_in_cset()) { 4372 oop forwardee; 4373 markOop m = obj->mark(); 4374 if (m->is_marked()) { 4375 forwardee = (oop) m->decode_pointer(); 4376 } else { 4377 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m); 4378 } 4379 assert(forwardee != NULL, "forwardee should not be NULL"); 4380 oopDesc::encode_store_heap_oop(p, forwardee); 4381 if (do_mark_object != G1MarkNone && forwardee != obj) { 4382 // If the object is self-forwarded we don't need to explicitly 4383 // mark it, the evacuation failure protocol will do so. 4384 mark_forwarded_object(obj, forwardee); 4385 } 4386 4387 if (barrier == G1BarrierKlass) { 4388 do_klass_barrier(p, forwardee); 4389 } 4390 } else { 4391 if (state.is_humongous()) { 4392 _g1->set_humongous_is_live(obj); 4393 } 4394 // The object is not in collection set. If we're a root scanning 4395 // closure during an initial mark pause then attempt to mark the object. 4396 if (do_mark_object == G1MarkFromRoot) { 4397 mark_object(obj); 4398 } 4399 } 4400 } 4401 4402 class G1ParEvacuateFollowersClosure : public VoidClosure { 4403 private: 4404 double _start_term; 4405 double _term_time; 4406 size_t _term_attempts; 4407 4408 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 4409 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 4410 protected: 4411 G1CollectedHeap* _g1h; 4412 G1ParScanThreadState* _par_scan_state; 4413 RefToScanQueueSet* _queues; 4414 ParallelTaskTerminator* _terminator; 4415 4416 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4417 RefToScanQueueSet* queues() { return _queues; } 4418 ParallelTaskTerminator* terminator() { return _terminator; } 4419 4420 public: 4421 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4422 G1ParScanThreadState* par_scan_state, 4423 RefToScanQueueSet* queues, 4424 ParallelTaskTerminator* terminator) 4425 : _g1h(g1h), _par_scan_state(par_scan_state), 4426 _queues(queues), _terminator(terminator), 4427 _start_term(0.0), _term_time(0.0), _term_attempts(0) {} 4428 4429 void do_void(); 4430 4431 double term_time() const { return _term_time; } 4432 size_t term_attempts() const { return _term_attempts; } 4433 4434 private: 4435 inline bool offer_termination(); 4436 }; 4437 4438 bool G1ParEvacuateFollowersClosure::offer_termination() { 4439 G1ParScanThreadState* const pss = par_scan_state(); 4440 start_term_time(); 4441 const bool res = terminator()->offer_termination(); 4442 end_term_time(); 4443 return res; 4444 } 4445 4446 void G1ParEvacuateFollowersClosure::do_void() { 4447 G1ParScanThreadState* const pss = par_scan_state(); 4448 pss->trim_queue(); 4449 do { 4450 pss->steal_and_trim_queue(queues()); 4451 } while (!offer_termination()); 4452 } 4453 4454 class G1KlassScanClosure : public KlassClosure { 4455 G1ParCopyHelper* _closure; 4456 bool _process_only_dirty; 4457 int _count; 4458 public: 4459 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4460 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4461 void do_klass(Klass* klass) { 4462 // If the klass has not been dirtied we know that there's 4463 // no references into the young gen and we can skip it. 4464 if (!_process_only_dirty || klass->has_modified_oops()) { 4465 // Clean the klass since we're going to scavenge all the metadata. 4466 klass->clear_modified_oops(); 4467 4468 // Tell the closure that this klass is the Klass to scavenge 4469 // and is the one to dirty if oops are left pointing into the young gen. 4470 _closure->set_scanned_klass(klass); 4471 4472 klass->oops_do(_closure); 4473 4474 _closure->set_scanned_klass(NULL); 4475 } 4476 _count++; 4477 } 4478 }; 4479 4480 class G1ParTask : public AbstractGangTask { 4481 protected: 4482 G1CollectedHeap* _g1h; 4483 G1ParScanThreadStateSet* _pss; 4484 RefToScanQueueSet* _queues; 4485 G1RootProcessor* _root_processor; 4486 ParallelTaskTerminator _terminator; 4487 uint _n_workers; 4488 4489 public: 4490 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 4491 : AbstractGangTask("G1 collection"), 4492 _g1h(g1h), 4493 _pss(per_thread_states), 4494 _queues(task_queues), 4495 _root_processor(root_processor), 4496 _terminator(n_workers, _queues), 4497 _n_workers(n_workers) 4498 {} 4499 4500 RefToScanQueueSet* queues() { return _queues; } 4501 4502 RefToScanQueue *work_queue(int i) { 4503 return queues()->queue(i); 4504 } 4505 4506 ParallelTaskTerminator* terminator() { return &_terminator; } 4507 4508 // Helps out with CLD processing. 4509 // 4510 // During InitialMark we need to: 4511 // 1) Scavenge all CLDs for the young GC. 4512 // 2) Mark all objects directly reachable from strong CLDs. 4513 template <G1Mark do_mark_object> 4514 class G1CLDClosure : public CLDClosure { 4515 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure; 4516 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure; 4517 G1KlassScanClosure _klass_in_cld_closure; 4518 bool _claim; 4519 4520 public: 4521 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure, 4522 bool only_young, bool claim) 4523 : _oop_closure(oop_closure), 4524 _oop_in_klass_closure(oop_closure->g1(), 4525 oop_closure->pss()), 4526 _klass_in_cld_closure(&_oop_in_klass_closure, only_young), 4527 _claim(claim) { 4528 4529 } 4530 4531 void do_cld(ClassLoaderData* cld) { 4532 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim); 4533 } 4534 }; 4535 4536 void work(uint worker_id) { 4537 if (worker_id >= _n_workers) return; // no work needed this round 4538 4539 double start_sec = os::elapsedTime(); 4540 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 4541 4542 { 4543 ResourceMark rm; 4544 HandleMark hm; 4545 4546 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4547 4548 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 4549 pss->set_ref_processor(rp); 4550 4551 bool only_young = _g1h->collector_state()->gcs_are_young(); 4552 4553 // Non-IM young GC. 4554 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, pss); 4555 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl, 4556 only_young, // Only process dirty klasses. 4557 false); // No need to claim CLDs. 4558 // IM young GC. 4559 // Strong roots closures. 4560 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, pss); 4561 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl, 4562 false, // Process all klasses. 4563 true); // Need to claim CLDs. 4564 // Weak roots closures. 4565 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, pss); 4566 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl, 4567 false, // Process all klasses. 4568 true); // Need to claim CLDs. 4569 4570 OopClosure* strong_root_cl; 4571 OopClosure* weak_root_cl; 4572 CLDClosure* strong_cld_cl; 4573 CLDClosure* weak_cld_cl; 4574 4575 bool trace_metadata = false; 4576 4577 if (_g1h->collector_state()->during_initial_mark_pause()) { 4578 // We also need to mark copied objects. 4579 strong_root_cl = &scan_mark_root_cl; 4580 strong_cld_cl = &scan_mark_cld_cl; 4581 if (ClassUnloadingWithConcurrentMark) { 4582 weak_root_cl = &scan_mark_weak_root_cl; 4583 weak_cld_cl = &scan_mark_weak_cld_cl; 4584 trace_metadata = true; 4585 } else { 4586 weak_root_cl = &scan_mark_root_cl; 4587 weak_cld_cl = &scan_mark_cld_cl; 4588 } 4589 } else { 4590 strong_root_cl = &scan_only_root_cl; 4591 weak_root_cl = &scan_only_root_cl; 4592 strong_cld_cl = &scan_only_cld_cl; 4593 weak_cld_cl = &scan_only_cld_cl; 4594 } 4595 4596 double start_strong_roots_sec = os::elapsedTime(); 4597 _root_processor->evacuate_roots(strong_root_cl, 4598 weak_root_cl, 4599 strong_cld_cl, 4600 weak_cld_cl, 4601 trace_metadata, 4602 worker_id); 4603 4604 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss); 4605 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl, 4606 weak_root_cl, 4607 worker_id); 4608 4609 _pss->add_cards_scanned(worker_id, cards_scanned); 4610 4611 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 4612 4613 double term_sec = 0.0; 4614 size_t evac_term_attempts = 0; 4615 { 4616 double start = os::elapsedTime(); 4617 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator); 4618 evac.do_void(); 4619 4620 evac_term_attempts = evac.term_attempts(); 4621 term_sec = evac.term_time(); 4622 double elapsed_sec = os::elapsedTime() - start; 4623 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 4624 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 4625 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 4626 } 4627 4628 assert(pss->queue_is_empty(), "should be empty"); 4629 4630 if (PrintTerminationStats) { 4631 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 4632 size_t lab_waste; 4633 size_t lab_undo_waste; 4634 pss->waste(lab_waste, lab_undo_waste); 4635 _g1h->print_termination_stats(gclog_or_tty, 4636 worker_id, 4637 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 4638 strong_roots_sec * 1000.0, /* strong roots time */ 4639 term_sec * 1000.0, /* evac term time */ 4640 evac_term_attempts, /* evac term attempts */ 4641 lab_waste, /* alloc buffer waste */ 4642 lab_undo_waste /* undo waste */ 4643 ); 4644 } 4645 4646 // Close the inner scope so that the ResourceMark and HandleMark 4647 // destructors are executed here and are included as part of the 4648 // "GC Worker Time". 4649 } 4650 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 4651 } 4652 }; 4653 4654 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) { 4655 st->print_raw_cr("GC Termination Stats"); 4656 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 4657 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo"); 4658 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 4659 } 4660 4661 void G1CollectedHeap::print_termination_stats(outputStream* const st, 4662 uint worker_id, 4663 double elapsed_ms, 4664 double strong_roots_ms, 4665 double term_ms, 4666 size_t term_attempts, 4667 size_t alloc_buffer_waste, 4668 size_t undo_waste) const { 4669 st->print_cr("%3d %9.2f %9.2f %6.2f " 4670 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 4671 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 4672 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 4673 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 4674 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 4675 alloc_buffer_waste * HeapWordSize / K, 4676 undo_waste * HeapWordSize / K); 4677 } 4678 4679 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4680 private: 4681 BoolObjectClosure* _is_alive; 4682 int _initial_string_table_size; 4683 int _initial_symbol_table_size; 4684 4685 bool _process_strings; 4686 int _strings_processed; 4687 int _strings_removed; 4688 4689 bool _process_symbols; 4690 int _symbols_processed; 4691 int _symbols_removed; 4692 4693 public: 4694 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4695 AbstractGangTask("String/Symbol Unlinking"), 4696 _is_alive(is_alive), 4697 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4698 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4699 4700 _initial_string_table_size = StringTable::the_table()->table_size(); 4701 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4702 if (process_strings) { 4703 StringTable::clear_parallel_claimed_index(); 4704 } 4705 if (process_symbols) { 4706 SymbolTable::clear_parallel_claimed_index(); 4707 } 4708 } 4709 4710 ~G1StringSymbolTableUnlinkTask() { 4711 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4712 err_msg("claim value %d after unlink less than initial string table size %d", 4713 StringTable::parallel_claimed_index(), _initial_string_table_size)); 4714 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4715 err_msg("claim value %d after unlink less than initial symbol table size %d", 4716 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 4717 4718 if (G1TraceStringSymbolTableScrubbing) { 4719 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4720 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, " 4721 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed", 4722 strings_processed(), strings_removed(), 4723 symbols_processed(), symbols_removed()); 4724 } 4725 } 4726 4727 void work(uint worker_id) { 4728 int strings_processed = 0; 4729 int strings_removed = 0; 4730 int symbols_processed = 0; 4731 int symbols_removed = 0; 4732 if (_process_strings) { 4733 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4734 Atomic::add(strings_processed, &_strings_processed); 4735 Atomic::add(strings_removed, &_strings_removed); 4736 } 4737 if (_process_symbols) { 4738 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 4739 Atomic::add(symbols_processed, &_symbols_processed); 4740 Atomic::add(symbols_removed, &_symbols_removed); 4741 } 4742 } 4743 4744 size_t strings_processed() const { return (size_t)_strings_processed; } 4745 size_t strings_removed() const { return (size_t)_strings_removed; } 4746 4747 size_t symbols_processed() const { return (size_t)_symbols_processed; } 4748 size_t symbols_removed() const { return (size_t)_symbols_removed; } 4749 }; 4750 4751 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 4752 private: 4753 static Monitor* _lock; 4754 4755 BoolObjectClosure* const _is_alive; 4756 const bool _unloading_occurred; 4757 const uint _num_workers; 4758 4759 // Variables used to claim nmethods. 4760 nmethod* _first_nmethod; 4761 volatile nmethod* _claimed_nmethod; 4762 4763 // The list of nmethods that need to be processed by the second pass. 4764 volatile nmethod* _postponed_list; 4765 volatile uint _num_entered_barrier; 4766 4767 public: 4768 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 4769 _is_alive(is_alive), 4770 _unloading_occurred(unloading_occurred), 4771 _num_workers(num_workers), 4772 _first_nmethod(NULL), 4773 _claimed_nmethod(NULL), 4774 _postponed_list(NULL), 4775 _num_entered_barrier(0) 4776 { 4777 nmethod::increase_unloading_clock(); 4778 // Get first alive nmethod 4779 NMethodIterator iter = NMethodIterator(); 4780 if(iter.next_alive()) { 4781 _first_nmethod = iter.method(); 4782 } 4783 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 4784 } 4785 4786 ~G1CodeCacheUnloadingTask() { 4787 CodeCache::verify_clean_inline_caches(); 4788 4789 CodeCache::set_needs_cache_clean(false); 4790 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 4791 4792 CodeCache::verify_icholder_relocations(); 4793 } 4794 4795 private: 4796 void add_to_postponed_list(nmethod* nm) { 4797 nmethod* old; 4798 do { 4799 old = (nmethod*)_postponed_list; 4800 nm->set_unloading_next(old); 4801 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 4802 } 4803 4804 void clean_nmethod(nmethod* nm) { 4805 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 4806 4807 if (postponed) { 4808 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 4809 add_to_postponed_list(nm); 4810 } 4811 4812 // Mark that this thread has been cleaned/unloaded. 4813 // After this call, it will be safe to ask if this nmethod was unloaded or not. 4814 nm->set_unloading_clock(nmethod::global_unloading_clock()); 4815 } 4816 4817 void clean_nmethod_postponed(nmethod* nm) { 4818 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 4819 } 4820 4821 static const int MaxClaimNmethods = 16; 4822 4823 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 4824 nmethod* first; 4825 NMethodIterator last; 4826 4827 do { 4828 *num_claimed_nmethods = 0; 4829 4830 first = (nmethod*)_claimed_nmethod; 4831 last = NMethodIterator(first); 4832 4833 if (first != NULL) { 4834 4835 for (int i = 0; i < MaxClaimNmethods; i++) { 4836 if (!last.next_alive()) { 4837 break; 4838 } 4839 claimed_nmethods[i] = last.method(); 4840 (*num_claimed_nmethods)++; 4841 } 4842 } 4843 4844 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 4845 } 4846 4847 nmethod* claim_postponed_nmethod() { 4848 nmethod* claim; 4849 nmethod* next; 4850 4851 do { 4852 claim = (nmethod*)_postponed_list; 4853 if (claim == NULL) { 4854 return NULL; 4855 } 4856 4857 next = claim->unloading_next(); 4858 4859 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 4860 4861 return claim; 4862 } 4863 4864 public: 4865 // Mark that we're done with the first pass of nmethod cleaning. 4866 void barrier_mark(uint worker_id) { 4867 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4868 _num_entered_barrier++; 4869 if (_num_entered_barrier == _num_workers) { 4870 ml.notify_all(); 4871 } 4872 } 4873 4874 // See if we have to wait for the other workers to 4875 // finish their first-pass nmethod cleaning work. 4876 void barrier_wait(uint worker_id) { 4877 if (_num_entered_barrier < _num_workers) { 4878 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4879 while (_num_entered_barrier < _num_workers) { 4880 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 4881 } 4882 } 4883 } 4884 4885 // Cleaning and unloading of nmethods. Some work has to be postponed 4886 // to the second pass, when we know which nmethods survive. 4887 void work_first_pass(uint worker_id) { 4888 // The first nmethods is claimed by the first worker. 4889 if (worker_id == 0 && _first_nmethod != NULL) { 4890 clean_nmethod(_first_nmethod); 4891 _first_nmethod = NULL; 4892 } 4893 4894 int num_claimed_nmethods; 4895 nmethod* claimed_nmethods[MaxClaimNmethods]; 4896 4897 while (true) { 4898 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 4899 4900 if (num_claimed_nmethods == 0) { 4901 break; 4902 } 4903 4904 for (int i = 0; i < num_claimed_nmethods; i++) { 4905 clean_nmethod(claimed_nmethods[i]); 4906 } 4907 } 4908 } 4909 4910 void work_second_pass(uint worker_id) { 4911 nmethod* nm; 4912 // Take care of postponed nmethods. 4913 while ((nm = claim_postponed_nmethod()) != NULL) { 4914 clean_nmethod_postponed(nm); 4915 } 4916 } 4917 }; 4918 4919 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 4920 4921 class G1KlassCleaningTask : public StackObj { 4922 BoolObjectClosure* _is_alive; 4923 volatile jint _clean_klass_tree_claimed; 4924 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 4925 4926 public: 4927 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 4928 _is_alive(is_alive), 4929 _clean_klass_tree_claimed(0), 4930 _klass_iterator() { 4931 } 4932 4933 private: 4934 bool claim_clean_klass_tree_task() { 4935 if (_clean_klass_tree_claimed) { 4936 return false; 4937 } 4938 4939 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 4940 } 4941 4942 InstanceKlass* claim_next_klass() { 4943 Klass* klass; 4944 do { 4945 klass =_klass_iterator.next_klass(); 4946 } while (klass != NULL && !klass->oop_is_instance()); 4947 4948 return (InstanceKlass*)klass; 4949 } 4950 4951 public: 4952 4953 void clean_klass(InstanceKlass* ik) { 4954 ik->clean_implementors_list(_is_alive); 4955 ik->clean_method_data(_is_alive); 4956 4957 // G1 specific cleanup work that has 4958 // been moved here to be done in parallel. 4959 ik->clean_dependent_nmethods(); 4960 } 4961 4962 void work() { 4963 ResourceMark rm; 4964 4965 // One worker will clean the subklass/sibling klass tree. 4966 if (claim_clean_klass_tree_task()) { 4967 Klass::clean_subklass_tree(_is_alive); 4968 } 4969 4970 // All workers will help cleaning the classes, 4971 InstanceKlass* klass; 4972 while ((klass = claim_next_klass()) != NULL) { 4973 clean_klass(klass); 4974 } 4975 } 4976 }; 4977 4978 // To minimize the remark pause times, the tasks below are done in parallel. 4979 class G1ParallelCleaningTask : public AbstractGangTask { 4980 private: 4981 G1StringSymbolTableUnlinkTask _string_symbol_task; 4982 G1CodeCacheUnloadingTask _code_cache_task; 4983 G1KlassCleaningTask _klass_cleaning_task; 4984 4985 public: 4986 // The constructor is run in the VMThread. 4987 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 4988 AbstractGangTask("Parallel Cleaning"), 4989 _string_symbol_task(is_alive, process_strings, process_symbols), 4990 _code_cache_task(num_workers, is_alive, unloading_occurred), 4991 _klass_cleaning_task(is_alive) { 4992 } 4993 4994 // The parallel work done by all worker threads. 4995 void work(uint worker_id) { 4996 // Do first pass of code cache cleaning. 4997 _code_cache_task.work_first_pass(worker_id); 4998 4999 // Let the threads mark that the first pass is done. 5000 _code_cache_task.barrier_mark(worker_id); 5001 5002 // Clean the Strings and Symbols. 5003 _string_symbol_task.work(worker_id); 5004 5005 // Wait for all workers to finish the first code cache cleaning pass. 5006 _code_cache_task.barrier_wait(worker_id); 5007 5008 // Do the second code cache cleaning work, which realize on 5009 // the liveness information gathered during the first pass. 5010 _code_cache_task.work_second_pass(worker_id); 5011 5012 // Clean all klasses that were not unloaded. 5013 _klass_cleaning_task.work(); 5014 } 5015 }; 5016 5017 5018 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 5019 bool process_strings, 5020 bool process_symbols, 5021 bool class_unloading_occurred) { 5022 uint n_workers = workers()->active_workers(); 5023 5024 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 5025 n_workers, class_unloading_occurred); 5026 workers()->run_task(&g1_unlink_task); 5027 } 5028 5029 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 5030 bool process_strings, bool process_symbols) { 5031 { 5032 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 5033 workers()->run_task(&g1_unlink_task); 5034 } 5035 5036 if (G1StringDedup::is_enabled()) { 5037 G1StringDedup::unlink(is_alive); 5038 } 5039 } 5040 5041 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 5042 private: 5043 DirtyCardQueueSet* _queue; 5044 public: 5045 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 5046 5047 virtual void work(uint worker_id) { 5048 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times(); 5049 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 5050 5051 RedirtyLoggedCardTableEntryClosure cl; 5052 _queue->par_apply_closure_to_all_completed_buffers(&cl); 5053 5054 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed()); 5055 } 5056 }; 5057 5058 void G1CollectedHeap::redirty_logged_cards() { 5059 double redirty_logged_cards_start = os::elapsedTime(); 5060 5061 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 5062 dirty_card_queue_set().reset_for_par_iteration(); 5063 workers()->run_task(&redirty_task); 5064 5065 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 5066 dcq.merge_bufferlists(&dirty_card_queue_set()); 5067 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 5068 5069 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 5070 } 5071 5072 // Weak Reference Processing support 5073 5074 // An always "is_alive" closure that is used to preserve referents. 5075 // If the object is non-null then it's alive. Used in the preservation 5076 // of referent objects that are pointed to by reference objects 5077 // discovered by the CM ref processor. 5078 class G1AlwaysAliveClosure: public BoolObjectClosure { 5079 G1CollectedHeap* _g1; 5080 public: 5081 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5082 bool do_object_b(oop p) { 5083 if (p != NULL) { 5084 return true; 5085 } 5086 return false; 5087 } 5088 }; 5089 5090 bool G1STWIsAliveClosure::do_object_b(oop p) { 5091 // An object is reachable if it is outside the collection set, 5092 // or is inside and copied. 5093 return !_g1->is_in_cset(p) || p->is_forwarded(); 5094 } 5095 5096 // Non Copying Keep Alive closure 5097 class G1KeepAliveClosure: public OopClosure { 5098 G1CollectedHeap* _g1; 5099 public: 5100 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5101 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 5102 void do_oop(oop* p) { 5103 oop obj = *p; 5104 assert(obj != NULL, "the caller should have filtered out NULL values"); 5105 5106 const InCSetState cset_state = _g1->in_cset_state(obj); 5107 if (!cset_state.is_in_cset_or_humongous()) { 5108 return; 5109 } 5110 if (cset_state.is_in_cset()) { 5111 assert( obj->is_forwarded(), "invariant" ); 5112 *p = obj->forwardee(); 5113 } else { 5114 assert(!obj->is_forwarded(), "invariant" ); 5115 assert(cset_state.is_humongous(), 5116 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value())); 5117 _g1->set_humongous_is_live(obj); 5118 } 5119 } 5120 }; 5121 5122 // Copying Keep Alive closure - can be called from both 5123 // serial and parallel code as long as different worker 5124 // threads utilize different G1ParScanThreadState instances 5125 // and different queues. 5126 5127 class G1CopyingKeepAliveClosure: public OopClosure { 5128 G1CollectedHeap* _g1h; 5129 OopClosure* _copy_non_heap_obj_cl; 5130 G1ParScanThreadState* _par_scan_state; 5131 5132 public: 5133 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 5134 OopClosure* non_heap_obj_cl, 5135 G1ParScanThreadState* pss): 5136 _g1h(g1h), 5137 _copy_non_heap_obj_cl(non_heap_obj_cl), 5138 _par_scan_state(pss) 5139 {} 5140 5141 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 5142 virtual void do_oop( oop* p) { do_oop_work(p); } 5143 5144 template <class T> void do_oop_work(T* p) { 5145 oop obj = oopDesc::load_decode_heap_oop(p); 5146 5147 if (_g1h->is_in_cset_or_humongous(obj)) { 5148 // If the referent object has been forwarded (either copied 5149 // to a new location or to itself in the event of an 5150 // evacuation failure) then we need to update the reference 5151 // field and, if both reference and referent are in the G1 5152 // heap, update the RSet for the referent. 5153 // 5154 // If the referent has not been forwarded then we have to keep 5155 // it alive by policy. Therefore we have copy the referent. 5156 // 5157 // If the reference field is in the G1 heap then we can push 5158 // on the PSS queue. When the queue is drained (after each 5159 // phase of reference processing) the object and it's followers 5160 // will be copied, the reference field set to point to the 5161 // new location, and the RSet updated. Otherwise we need to 5162 // use the the non-heap or metadata closures directly to copy 5163 // the referent object and update the pointer, while avoiding 5164 // updating the RSet. 5165 5166 if (_g1h->is_in_g1_reserved(p)) { 5167 _par_scan_state->push_on_queue(p); 5168 } else { 5169 assert(!Metaspace::contains((const void*)p), 5170 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p))); 5171 _copy_non_heap_obj_cl->do_oop(p); 5172 } 5173 } 5174 } 5175 }; 5176 5177 // Serial drain queue closure. Called as the 'complete_gc' 5178 // closure for each discovered list in some of the 5179 // reference processing phases. 5180 5181 class G1STWDrainQueueClosure: public VoidClosure { 5182 protected: 5183 G1CollectedHeap* _g1h; 5184 G1ParScanThreadState* _par_scan_state; 5185 5186 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5187 5188 public: 5189 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5190 _g1h(g1h), 5191 _par_scan_state(pss) 5192 { } 5193 5194 void do_void() { 5195 G1ParScanThreadState* const pss = par_scan_state(); 5196 pss->trim_queue(); 5197 } 5198 }; 5199 5200 // Parallel Reference Processing closures 5201 5202 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5203 // processing during G1 evacuation pauses. 5204 5205 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5206 private: 5207 G1CollectedHeap* _g1h; 5208 G1ParScanThreadStateSet* _pss; 5209 RefToScanQueueSet* _queues; 5210 WorkGang* _workers; 5211 uint _active_workers; 5212 5213 public: 5214 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5215 G1ParScanThreadStateSet* per_thread_states, 5216 WorkGang* workers, 5217 RefToScanQueueSet *task_queues, 5218 uint n_workers) : 5219 _g1h(g1h), 5220 _pss(per_thread_states), 5221 _queues(task_queues), 5222 _workers(workers), 5223 _active_workers(n_workers) 5224 { 5225 assert(n_workers > 0, "shouldn't call this otherwise"); 5226 } 5227 5228 // Executes the given task using concurrent marking worker threads. 5229 virtual void execute(ProcessTask& task); 5230 virtual void execute(EnqueueTask& task); 5231 }; 5232 5233 // Gang task for possibly parallel reference processing 5234 5235 class G1STWRefProcTaskProxy: public AbstractGangTask { 5236 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5237 ProcessTask& _proc_task; 5238 G1CollectedHeap* _g1h; 5239 G1ParScanThreadStateSet* _pss; 5240 RefToScanQueueSet* _task_queues; 5241 ParallelTaskTerminator* _terminator; 5242 5243 public: 5244 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5245 G1CollectedHeap* g1h, 5246 G1ParScanThreadStateSet* per_thread_states, 5247 RefToScanQueueSet *task_queues, 5248 ParallelTaskTerminator* terminator) : 5249 AbstractGangTask("Process reference objects in parallel"), 5250 _proc_task(proc_task), 5251 _g1h(g1h), 5252 _pss(per_thread_states), 5253 _task_queues(task_queues), 5254 _terminator(terminator) 5255 {} 5256 5257 virtual void work(uint worker_id) { 5258 // The reference processing task executed by a single worker. 5259 ResourceMark rm; 5260 HandleMark hm; 5261 5262 G1STWIsAliveClosure is_alive(_g1h); 5263 5264 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 5265 pss->set_ref_processor(NULL); 5266 5267 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, pss); 5268 5269 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, pss); 5270 5271 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5272 5273 if (_g1h->collector_state()->during_initial_mark_pause()) { 5274 // We also need to mark copied objects. 5275 copy_non_heap_cl = ©_mark_non_heap_cl; 5276 } 5277 5278 // Keep alive closure. 5279 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, pss); 5280 5281 // Complete GC closure 5282 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator); 5283 5284 // Call the reference processing task's work routine. 5285 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5286 5287 // Note we cannot assert that the refs array is empty here as not all 5288 // of the processing tasks (specifically phase2 - pp2_work) execute 5289 // the complete_gc closure (which ordinarily would drain the queue) so 5290 // the queue may not be empty. 5291 } 5292 }; 5293 5294 // Driver routine for parallel reference processing. 5295 // Creates an instance of the ref processing gang 5296 // task and has the worker threads execute it. 5297 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5298 assert(_workers != NULL, "Need parallel worker threads."); 5299 5300 ParallelTaskTerminator terminator(_active_workers, _queues); 5301 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 5302 5303 _workers->run_task(&proc_task_proxy); 5304 } 5305 5306 // Gang task for parallel reference enqueueing. 5307 5308 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5309 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5310 EnqueueTask& _enq_task; 5311 5312 public: 5313 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5314 AbstractGangTask("Enqueue reference objects in parallel"), 5315 _enq_task(enq_task) 5316 { } 5317 5318 virtual void work(uint worker_id) { 5319 _enq_task.work(worker_id); 5320 } 5321 }; 5322 5323 // Driver routine for parallel reference enqueueing. 5324 // Creates an instance of the ref enqueueing gang 5325 // task and has the worker threads execute it. 5326 5327 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5328 assert(_workers != NULL, "Need parallel worker threads."); 5329 5330 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5331 5332 _workers->run_task(&enq_task_proxy); 5333 } 5334 5335 // End of weak reference support closures 5336 5337 // Abstract task used to preserve (i.e. copy) any referent objects 5338 // that are in the collection set and are pointed to by reference 5339 // objects discovered by the CM ref processor. 5340 5341 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5342 protected: 5343 G1CollectedHeap* _g1h; 5344 G1ParScanThreadStateSet* _pss; 5345 RefToScanQueueSet* _queues; 5346 ParallelTaskTerminator _terminator; 5347 uint _n_workers; 5348 5349 public: 5350 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) : 5351 AbstractGangTask("ParPreserveCMReferents"), 5352 _g1h(g1h), 5353 _pss(per_thread_states), 5354 _queues(task_queues), 5355 _terminator(workers, _queues), 5356 _n_workers(workers) 5357 { } 5358 5359 void work(uint worker_id) { 5360 ResourceMark rm; 5361 HandleMark hm; 5362 5363 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 5364 pss->set_ref_processor(NULL); 5365 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 5366 5367 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, pss); 5368 5369 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, pss); 5370 5371 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5372 5373 if (_g1h->collector_state()->during_initial_mark_pause()) { 5374 // We also need to mark copied objects. 5375 copy_non_heap_cl = ©_mark_non_heap_cl; 5376 } 5377 5378 // Is alive closure 5379 G1AlwaysAliveClosure always_alive(_g1h); 5380 5381 // Copying keep alive closure. Applied to referent objects that need 5382 // to be copied. 5383 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, pss); 5384 5385 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5386 5387 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5388 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5389 5390 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5391 // So this must be true - but assert just in case someone decides to 5392 // change the worker ids. 5393 assert(worker_id < limit, "sanity"); 5394 assert(!rp->discovery_is_atomic(), "check this code"); 5395 5396 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5397 for (uint idx = worker_id; idx < limit; idx += stride) { 5398 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5399 5400 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5401 while (iter.has_next()) { 5402 // Since discovery is not atomic for the CM ref processor, we 5403 // can see some null referent objects. 5404 iter.load_ptrs(DEBUG_ONLY(true)); 5405 oop ref = iter.obj(); 5406 5407 // This will filter nulls. 5408 if (iter.is_referent_alive()) { 5409 iter.make_referent_alive(); 5410 } 5411 iter.move_to_next(); 5412 } 5413 } 5414 5415 // Drain the queue - which may cause stealing 5416 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator); 5417 drain_queue.do_void(); 5418 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5419 assert(pss->queue_is_empty(), "should be"); 5420 } 5421 }; 5422 5423 // Weak Reference processing during an evacuation pause (part 1). 5424 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 5425 double ref_proc_start = os::elapsedTime(); 5426 5427 ReferenceProcessor* rp = _ref_processor_stw; 5428 assert(rp->discovery_enabled(), "should have been enabled"); 5429 5430 // Any reference objects, in the collection set, that were 'discovered' 5431 // by the CM ref processor should have already been copied (either by 5432 // applying the external root copy closure to the discovered lists, or 5433 // by following an RSet entry). 5434 // 5435 // But some of the referents, that are in the collection set, that these 5436 // reference objects point to may not have been copied: the STW ref 5437 // processor would have seen that the reference object had already 5438 // been 'discovered' and would have skipped discovering the reference, 5439 // but would not have treated the reference object as a regular oop. 5440 // As a result the copy closure would not have been applied to the 5441 // referent object. 5442 // 5443 // We need to explicitly copy these referent objects - the references 5444 // will be processed at the end of remarking. 5445 // 5446 // We also need to do this copying before we process the reference 5447 // objects discovered by the STW ref processor in case one of these 5448 // referents points to another object which is also referenced by an 5449 // object discovered by the STW ref processor. 5450 5451 uint no_of_gc_workers = workers()->active_workers(); 5452 5453 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5454 per_thread_states, 5455 no_of_gc_workers, 5456 _task_queues); 5457 5458 workers()->run_task(&keep_cm_referents); 5459 5460 // Closure to test whether a referent is alive. 5461 G1STWIsAliveClosure is_alive(this); 5462 5463 // Even when parallel reference processing is enabled, the processing 5464 // of JNI refs is serial and performed serially by the current thread 5465 // rather than by a worker. The following PSS will be used for processing 5466 // JNI refs. 5467 5468 // Use only a single queue for this PSS. 5469 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 5470 pss->set_ref_processor(NULL); 5471 assert(pss->queue_is_empty(), "pre-condition"); 5472 5473 // We do not embed a reference processor in the copying/scanning 5474 // closures while we're actually processing the discovered 5475 // reference objects. 5476 5477 G1ParScanExtRootClosure only_copy_non_heap_cl(this, pss); 5478 5479 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, pss); 5480 5481 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5482 5483 if (collector_state()->during_initial_mark_pause()) { 5484 // We also need to mark copied objects. 5485 copy_non_heap_cl = ©_mark_non_heap_cl; 5486 } 5487 5488 // Keep alive closure. 5489 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, pss); 5490 5491 // Serial Complete GC closure 5492 G1STWDrainQueueClosure drain_queue(this, pss); 5493 5494 // Setup the soft refs policy... 5495 rp->setup_policy(false); 5496 5497 ReferenceProcessorStats stats; 5498 if (!rp->processing_is_mt()) { 5499 // Serial reference processing... 5500 stats = rp->process_discovered_references(&is_alive, 5501 &keep_alive, 5502 &drain_queue, 5503 NULL, 5504 _gc_timer_stw, 5505 _gc_tracer_stw->gc_id()); 5506 } else { 5507 // Parallel reference processing 5508 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5509 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5510 5511 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers); 5512 stats = rp->process_discovered_references(&is_alive, 5513 &keep_alive, 5514 &drain_queue, 5515 &par_task_executor, 5516 _gc_timer_stw, 5517 _gc_tracer_stw->gc_id()); 5518 } 5519 5520 _gc_tracer_stw->report_gc_reference_stats(stats); 5521 5522 // We have completed copying any necessary live referent objects. 5523 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 5524 5525 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5526 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5527 } 5528 5529 // Weak Reference processing during an evacuation pause (part 2). 5530 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 5531 double ref_enq_start = os::elapsedTime(); 5532 5533 ReferenceProcessor* rp = _ref_processor_stw; 5534 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5535 5536 // Now enqueue any remaining on the discovered lists on to 5537 // the pending list. 5538 if (!rp->processing_is_mt()) { 5539 // Serial reference processing... 5540 rp->enqueue_discovered_references(); 5541 } else { 5542 // Parallel reference enqueueing 5543 5544 uint n_workers = workers()->active_workers(); 5545 5546 assert(rp->num_q() == n_workers, "sanity"); 5547 assert(n_workers <= rp->max_num_q(), "sanity"); 5548 5549 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers); 5550 rp->enqueue_discovered_references(&par_task_executor); 5551 } 5552 5553 rp->verify_no_references_recorded(); 5554 assert(!rp->discovery_enabled(), "should have been disabled"); 5555 5556 // FIXME 5557 // CM's reference processing also cleans up the string and symbol tables. 5558 // Should we do that here also? We could, but it is a serial operation 5559 // and could significantly increase the pause time. 5560 5561 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5562 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5563 } 5564 5565 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 5566 _expand_heap_after_alloc_failure = true; 5567 _evacuation_failed = false; 5568 5569 // Should G1EvacuationFailureALot be in effect for this GC? 5570 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5571 5572 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5573 5574 // Disable the hot card cache. 5575 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5576 hot_card_cache->reset_hot_cache_claimed_index(); 5577 hot_card_cache->set_use_cache(false); 5578 5579 const uint n_workers = workers()->active_workers(); 5580 5581 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5582 double start_par_time_sec = os::elapsedTime(); 5583 double end_par_time_sec; 5584 5585 { 5586 G1RootProcessor root_processor(this, n_workers); 5587 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 5588 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5589 if (collector_state()->during_initial_mark_pause()) { 5590 ClassLoaderDataGraph::clear_claimed_marks(); 5591 } 5592 5593 // The individual threads will set their evac-failure closures. 5594 if (PrintTerminationStats) { 5595 print_termination_stats_hdr(gclog_or_tty); 5596 } 5597 5598 workers()->run_task(&g1_par_task); 5599 end_par_time_sec = os::elapsedTime(); 5600 5601 // Closing the inner scope will execute the destructor 5602 // for the G1RootProcessor object. We record the current 5603 // elapsed time before closing the scope so that time 5604 // taken for the destructor is NOT included in the 5605 // reported parallel time. 5606 } 5607 5608 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 5609 5610 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5611 phase_times->record_par_time(par_time_ms); 5612 5613 double code_root_fixup_time_ms = 5614 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5615 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 5616 5617 // Process any discovered reference objects - we have 5618 // to do this _before_ we retire the GC alloc regions 5619 // as we may have to copy some 'reachable' referent 5620 // objects (and their reachable sub-graphs) that were 5621 // not copied during the pause. 5622 process_discovered_references(per_thread_states); 5623 5624 if (G1StringDedup::is_enabled()) { 5625 double fixup_start = os::elapsedTime(); 5626 5627 G1STWIsAliveClosure is_alive(this); 5628 G1KeepAliveClosure keep_alive(this); 5629 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times); 5630 5631 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 5632 phase_times->record_string_dedup_fixup_time(fixup_time_ms); 5633 } 5634 5635 _allocator->release_gc_alloc_regions(evacuation_info); 5636 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5637 5638 per_thread_states->flush(); 5639 5640 record_obj_copy_mem_stats(); 5641 5642 // Reset and re-enable the hot card cache. 5643 // Note the counts for the cards in the regions in the 5644 // collection set are reset when the collection set is freed. 5645 hot_card_cache->reset_hot_cache(); 5646 hot_card_cache->set_use_cache(true); 5647 5648 purge_code_root_memory(); 5649 5650 if (evacuation_failed()) { 5651 remove_self_forwarding_pointers(); 5652 5653 // Reset the G1EvacuationFailureALot counters and flags 5654 // Note: the values are reset only when an actual 5655 // evacuation failure occurs. 5656 NOT_PRODUCT(reset_evacuation_should_fail();) 5657 } 5658 5659 // Enqueue any remaining references remaining on the STW 5660 // reference processor's discovered lists. We need to do 5661 // this after the card table is cleaned (and verified) as 5662 // the act of enqueueing entries on to the pending list 5663 // will log these updates (and dirty their associated 5664 // cards). We need these updates logged to update any 5665 // RSets. 5666 enqueue_discovered_references(per_thread_states); 5667 5668 redirty_logged_cards(); 5669 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5670 } 5671 5672 void G1CollectedHeap::record_obj_copy_mem_stats() { 5673 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 5674 create_g1_evac_summary(&_old_evac_stats)); 5675 } 5676 5677 void G1CollectedHeap::free_region(HeapRegion* hr, 5678 FreeRegionList* free_list, 5679 bool par, 5680 bool locked) { 5681 assert(!hr->is_free(), "the region should not be free"); 5682 assert(!hr->is_empty(), "the region should not be empty"); 5683 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 5684 assert(free_list != NULL, "pre-condition"); 5685 5686 if (G1VerifyBitmaps) { 5687 MemRegion mr(hr->bottom(), hr->end()); 5688 concurrent_mark()->clearRangePrevBitmap(mr); 5689 } 5690 5691 // Clear the card counts for this region. 5692 // Note: we only need to do this if the region is not young 5693 // (since we don't refine cards in young regions). 5694 if (!hr->is_young()) { 5695 _cg1r->hot_card_cache()->reset_card_counts(hr); 5696 } 5697 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5698 free_list->add_ordered(hr); 5699 } 5700 5701 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5702 FreeRegionList* free_list, 5703 bool par) { 5704 assert(hr->is_starts_humongous(), "this is only for starts humongous regions"); 5705 assert(free_list != NULL, "pre-condition"); 5706 5707 size_t hr_capacity = hr->capacity(); 5708 // We need to read this before we make the region non-humongous, 5709 // otherwise the information will be gone. 5710 uint last_index = hr->last_hc_index(); 5711 hr->clear_humongous(); 5712 free_region(hr, free_list, par); 5713 5714 uint i = hr->hrm_index() + 1; 5715 while (i < last_index) { 5716 HeapRegion* curr_hr = region_at(i); 5717 assert(curr_hr->is_continues_humongous(), "invariant"); 5718 curr_hr->clear_humongous(); 5719 free_region(curr_hr, free_list, par); 5720 i += 1; 5721 } 5722 } 5723 5724 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 5725 const HeapRegionSetCount& humongous_regions_removed) { 5726 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5727 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5728 _old_set.bulk_remove(old_regions_removed); 5729 _humongous_set.bulk_remove(humongous_regions_removed); 5730 } 5731 5732 } 5733 5734 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 5735 assert(list != NULL, "list can't be null"); 5736 if (!list->is_empty()) { 5737 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5738 _hrm.insert_list_into_free_list(list); 5739 } 5740 } 5741 5742 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 5743 decrease_used(bytes); 5744 } 5745 5746 class G1ParCleanupCTTask : public AbstractGangTask { 5747 G1SATBCardTableModRefBS* _ct_bs; 5748 G1CollectedHeap* _g1h; 5749 HeapRegion* volatile _su_head; 5750 public: 5751 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 5752 G1CollectedHeap* g1h) : 5753 AbstractGangTask("G1 Par Cleanup CT Task"), 5754 _ct_bs(ct_bs), _g1h(g1h) { } 5755 5756 void work(uint worker_id) { 5757 HeapRegion* r; 5758 while (r = _g1h->pop_dirty_cards_region()) { 5759 clear_cards(r); 5760 } 5761 } 5762 5763 void clear_cards(HeapRegion* r) { 5764 // Cards of the survivors should have already been dirtied. 5765 if (!r->is_survivor()) { 5766 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5767 } 5768 } 5769 }; 5770 5771 #ifndef PRODUCT 5772 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5773 G1CollectedHeap* _g1h; 5774 G1SATBCardTableModRefBS* _ct_bs; 5775 public: 5776 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 5777 : _g1h(g1h), _ct_bs(ct_bs) { } 5778 virtual bool doHeapRegion(HeapRegion* r) { 5779 if (r->is_survivor()) { 5780 _g1h->verify_dirty_region(r); 5781 } else { 5782 _g1h->verify_not_dirty_region(r); 5783 } 5784 return false; 5785 } 5786 }; 5787 5788 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5789 // All of the region should be clean. 5790 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5791 MemRegion mr(hr->bottom(), hr->end()); 5792 ct_bs->verify_not_dirty_region(mr); 5793 } 5794 5795 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5796 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5797 // dirty allocated blocks as they allocate them. The thread that 5798 // retires each region and replaces it with a new one will do a 5799 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5800 // not dirty that area (one less thing to have to do while holding 5801 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5802 // is dirty. 5803 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5804 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5805 if (hr->is_young()) { 5806 ct_bs->verify_g1_young_region(mr); 5807 } else { 5808 ct_bs->verify_dirty_region(mr); 5809 } 5810 } 5811 5812 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5813 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5814 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5815 verify_dirty_region(hr); 5816 } 5817 } 5818 5819 void G1CollectedHeap::verify_dirty_young_regions() { 5820 verify_dirty_young_list(_young_list->first_region()); 5821 } 5822 5823 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 5824 HeapWord* tams, HeapWord* end) { 5825 guarantee(tams <= end, 5826 err_msg("tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end))); 5827 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 5828 if (result < end) { 5829 gclog_or_tty->cr(); 5830 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT, 5831 bitmap_name, p2i(result)); 5832 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT, 5833 bitmap_name, p2i(tams), p2i(end)); 5834 return false; 5835 } 5836 return true; 5837 } 5838 5839 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 5840 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 5841 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 5842 5843 HeapWord* bottom = hr->bottom(); 5844 HeapWord* ptams = hr->prev_top_at_mark_start(); 5845 HeapWord* ntams = hr->next_top_at_mark_start(); 5846 HeapWord* end = hr->end(); 5847 5848 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 5849 5850 bool res_n = true; 5851 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 5852 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 5853 // if we happen to be in that state. 5854 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) { 5855 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 5856 } 5857 if (!res_p || !res_n) { 5858 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT, 5859 HR_FORMAT_PARAMS(hr)); 5860 gclog_or_tty->print_cr("#### Caller: %s", caller); 5861 return false; 5862 } 5863 return true; 5864 } 5865 5866 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 5867 if (!G1VerifyBitmaps) return; 5868 5869 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 5870 } 5871 5872 class G1VerifyBitmapClosure : public HeapRegionClosure { 5873 private: 5874 const char* _caller; 5875 G1CollectedHeap* _g1h; 5876 bool _failures; 5877 5878 public: 5879 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 5880 _caller(caller), _g1h(g1h), _failures(false) { } 5881 5882 bool failures() { return _failures; } 5883 5884 virtual bool doHeapRegion(HeapRegion* hr) { 5885 if (hr->is_continues_humongous()) return false; 5886 5887 bool result = _g1h->verify_bitmaps(_caller, hr); 5888 if (!result) { 5889 _failures = true; 5890 } 5891 return false; 5892 } 5893 }; 5894 5895 void G1CollectedHeap::check_bitmaps(const char* caller) { 5896 if (!G1VerifyBitmaps) return; 5897 5898 G1VerifyBitmapClosure cl(caller, this); 5899 heap_region_iterate(&cl); 5900 guarantee(!cl.failures(), "bitmap verification"); 5901 } 5902 5903 class G1CheckCSetFastTableClosure : public HeapRegionClosure { 5904 private: 5905 bool _failures; 5906 public: 5907 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { } 5908 5909 virtual bool doHeapRegion(HeapRegion* hr) { 5910 uint i = hr->hrm_index(); 5911 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i); 5912 if (hr->is_humongous()) { 5913 if (hr->in_collection_set()) { 5914 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i); 5915 _failures = true; 5916 return true; 5917 } 5918 if (cset_state.is_in_cset()) { 5919 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i); 5920 _failures = true; 5921 return true; 5922 } 5923 if (hr->is_continues_humongous() && cset_state.is_humongous()) { 5924 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i); 5925 _failures = true; 5926 return true; 5927 } 5928 } else { 5929 if (cset_state.is_humongous()) { 5930 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i); 5931 _failures = true; 5932 return true; 5933 } 5934 if (hr->in_collection_set() != cset_state.is_in_cset()) { 5935 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u", 5936 hr->in_collection_set(), cset_state.value(), i); 5937 _failures = true; 5938 return true; 5939 } 5940 if (cset_state.is_in_cset()) { 5941 if (hr->is_young() != (cset_state.is_young())) { 5942 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u", 5943 hr->is_young(), cset_state.value(), i); 5944 _failures = true; 5945 return true; 5946 } 5947 if (hr->is_old() != (cset_state.is_old())) { 5948 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u", 5949 hr->is_old(), cset_state.value(), i); 5950 _failures = true; 5951 return true; 5952 } 5953 } 5954 } 5955 return false; 5956 } 5957 5958 bool failures() const { return _failures; } 5959 }; 5960 5961 bool G1CollectedHeap::check_cset_fast_test() { 5962 G1CheckCSetFastTableClosure cl; 5963 _hrm.iterate(&cl); 5964 return !cl.failures(); 5965 } 5966 #endif // PRODUCT 5967 5968 void G1CollectedHeap::cleanUpCardTable() { 5969 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5970 double start = os::elapsedTime(); 5971 5972 { 5973 // Iterate over the dirty cards region list. 5974 G1ParCleanupCTTask cleanup_task(ct_bs, this); 5975 5976 workers()->run_task(&cleanup_task); 5977 #ifndef PRODUCT 5978 if (G1VerifyCTCleanup || VerifyAfterGC) { 5979 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 5980 heap_region_iterate(&cleanup_verifier); 5981 } 5982 #endif 5983 } 5984 5985 double elapsed = os::elapsedTime() - start; 5986 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 5987 } 5988 5989 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 5990 size_t pre_used = 0; 5991 FreeRegionList local_free_list("Local List for CSet Freeing"); 5992 5993 double young_time_ms = 0.0; 5994 double non_young_time_ms = 0.0; 5995 5996 // Since the collection set is a superset of the the young list, 5997 // all we need to do to clear the young list is clear its 5998 // head and length, and unlink any young regions in the code below 5999 _young_list->clear(); 6000 6001 G1CollectorPolicy* policy = g1_policy(); 6002 6003 double start_sec = os::elapsedTime(); 6004 bool non_young = true; 6005 6006 HeapRegion* cur = cs_head; 6007 int age_bound = -1; 6008 size_t rs_lengths = 0; 6009 6010 while (cur != NULL) { 6011 assert(!is_on_master_free_list(cur), "sanity"); 6012 if (non_young) { 6013 if (cur->is_young()) { 6014 double end_sec = os::elapsedTime(); 6015 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6016 non_young_time_ms += elapsed_ms; 6017 6018 start_sec = os::elapsedTime(); 6019 non_young = false; 6020 } 6021 } else { 6022 if (!cur->is_young()) { 6023 double end_sec = os::elapsedTime(); 6024 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6025 young_time_ms += elapsed_ms; 6026 6027 start_sec = os::elapsedTime(); 6028 non_young = true; 6029 } 6030 } 6031 6032 rs_lengths += cur->rem_set()->occupied_locked(); 6033 6034 HeapRegion* next = cur->next_in_collection_set(); 6035 assert(cur->in_collection_set(), "bad CS"); 6036 cur->set_next_in_collection_set(NULL); 6037 clear_in_cset(cur); 6038 6039 if (cur->is_young()) { 6040 int index = cur->young_index_in_cset(); 6041 assert(index != -1, "invariant"); 6042 assert((uint) index < policy->young_cset_region_length(), "invariant"); 6043 size_t words_survived = surviving_young_words[index]; 6044 cur->record_surv_words_in_group(words_survived); 6045 6046 // At this point the we have 'popped' cur from the collection set 6047 // (linked via next_in_collection_set()) but it is still in the 6048 // young list (linked via next_young_region()). Clear the 6049 // _next_young_region field. 6050 cur->set_next_young_region(NULL); 6051 } else { 6052 int index = cur->young_index_in_cset(); 6053 assert(index == -1, "invariant"); 6054 } 6055 6056 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 6057 (!cur->is_young() && cur->young_index_in_cset() == -1), 6058 "invariant" ); 6059 6060 if (!cur->evacuation_failed()) { 6061 MemRegion used_mr = cur->used_region(); 6062 6063 // And the region is empty. 6064 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 6065 pre_used += cur->used(); 6066 free_region(cur, &local_free_list, false /* par */, true /* locked */); 6067 } else { 6068 cur->uninstall_surv_rate_group(); 6069 if (cur->is_young()) { 6070 cur->set_young_index_in_cset(-1); 6071 } 6072 cur->set_evacuation_failed(false); 6073 // The region is now considered to be old. 6074 cur->set_old(); 6075 // Do some allocation statistics accounting. Regions that failed evacuation 6076 // are always made old, so there is no need to update anything in the young 6077 // gen statistics, but we need to update old gen statistics. 6078 size_t used_words = cur->marked_bytes() / HeapWordSize; 6079 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words); 6080 _old_set.add(cur); 6081 evacuation_info.increment_collectionset_used_after(cur->used()); 6082 } 6083 cur = next; 6084 } 6085 6086 evacuation_info.set_regions_freed(local_free_list.length()); 6087 policy->record_max_rs_lengths(rs_lengths); 6088 policy->cset_regions_freed(); 6089 6090 double end_sec = os::elapsedTime(); 6091 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6092 6093 if (non_young) { 6094 non_young_time_ms += elapsed_ms; 6095 } else { 6096 young_time_ms += elapsed_ms; 6097 } 6098 6099 prepend_to_freelist(&local_free_list); 6100 decrement_summary_bytes(pre_used); 6101 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 6102 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 6103 } 6104 6105 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 6106 private: 6107 FreeRegionList* _free_region_list; 6108 HeapRegionSet* _proxy_set; 6109 HeapRegionSetCount _humongous_regions_removed; 6110 size_t _freed_bytes; 6111 public: 6112 6113 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 6114 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 6115 } 6116 6117 virtual bool doHeapRegion(HeapRegion* r) { 6118 if (!r->is_starts_humongous()) { 6119 return false; 6120 } 6121 6122 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 6123 6124 oop obj = (oop)r->bottom(); 6125 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 6126 6127 // The following checks whether the humongous object is live are sufficient. 6128 // The main additional check (in addition to having a reference from the roots 6129 // or the young gen) is whether the humongous object has a remembered set entry. 6130 // 6131 // A humongous object cannot be live if there is no remembered set for it 6132 // because: 6133 // - there can be no references from within humongous starts regions referencing 6134 // the object because we never allocate other objects into them. 6135 // (I.e. there are no intra-region references that may be missed by the 6136 // remembered set) 6137 // - as soon there is a remembered set entry to the humongous starts region 6138 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 6139 // until the end of a concurrent mark. 6140 // 6141 // It is not required to check whether the object has been found dead by marking 6142 // or not, in fact it would prevent reclamation within a concurrent cycle, as 6143 // all objects allocated during that time are considered live. 6144 // SATB marking is even more conservative than the remembered set. 6145 // So if at this point in the collection there is no remembered set entry, 6146 // nobody has a reference to it. 6147 // At the start of collection we flush all refinement logs, and remembered sets 6148 // are completely up-to-date wrt to references to the humongous object. 6149 // 6150 // Other implementation considerations: 6151 // - never consider object arrays at this time because they would pose 6152 // considerable effort for cleaning up the the remembered sets. This is 6153 // required because stale remembered sets might reference locations that 6154 // are currently allocated into. 6155 uint region_idx = r->hrm_index(); 6156 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 6157 !r->rem_set()->is_empty()) { 6158 6159 if (G1TraceEagerReclaimHumongousObjects) { 6160 gclog_or_tty->print_cr("Live humongous region %u size " SIZE_FORMAT " start " PTR_FORMAT " length %u with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d", 6161 region_idx, 6162 (size_t)obj->size() * HeapWordSize, 6163 p2i(r->bottom()), 6164 r->region_num(), 6165 r->rem_set()->occupied(), 6166 r->rem_set()->strong_code_roots_list_length(), 6167 next_bitmap->isMarked(r->bottom()), 6168 g1h->is_humongous_reclaim_candidate(region_idx), 6169 obj->is_typeArray() 6170 ); 6171 } 6172 6173 return false; 6174 } 6175 6176 guarantee(obj->is_typeArray(), 6177 err_msg("Only eagerly reclaiming type arrays is supported, but the object " 6178 PTR_FORMAT " is not.", 6179 p2i(r->bottom()))); 6180 6181 if (G1TraceEagerReclaimHumongousObjects) { 6182 gclog_or_tty->print_cr("Dead humongous region %u size " SIZE_FORMAT " start " PTR_FORMAT " length %u with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d", 6183 region_idx, 6184 (size_t)obj->size() * HeapWordSize, 6185 p2i(r->bottom()), 6186 r->region_num(), 6187 r->rem_set()->occupied(), 6188 r->rem_set()->strong_code_roots_list_length(), 6189 next_bitmap->isMarked(r->bottom()), 6190 g1h->is_humongous_reclaim_candidate(region_idx), 6191 obj->is_typeArray() 6192 ); 6193 } 6194 // Need to clear mark bit of the humongous object if already set. 6195 if (next_bitmap->isMarked(r->bottom())) { 6196 next_bitmap->clear(r->bottom()); 6197 } 6198 _freed_bytes += r->used(); 6199 r->set_containing_set(NULL); 6200 _humongous_regions_removed.increment(1u, r->capacity()); 6201 g1h->free_humongous_region(r, _free_region_list, false); 6202 6203 return false; 6204 } 6205 6206 HeapRegionSetCount& humongous_free_count() { 6207 return _humongous_regions_removed; 6208 } 6209 6210 size_t bytes_freed() const { 6211 return _freed_bytes; 6212 } 6213 6214 size_t humongous_reclaimed() const { 6215 return _humongous_regions_removed.length(); 6216 } 6217 }; 6218 6219 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 6220 assert_at_safepoint(true); 6221 6222 if (!G1EagerReclaimHumongousObjects || 6223 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) { 6224 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 6225 return; 6226 } 6227 6228 double start_time = os::elapsedTime(); 6229 6230 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 6231 6232 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 6233 heap_region_iterate(&cl); 6234 6235 HeapRegionSetCount empty_set; 6236 remove_from_old_sets(empty_set, cl.humongous_free_count()); 6237 6238 G1HRPrinter* hrp = hr_printer(); 6239 if (hrp->is_active()) { 6240 FreeRegionListIterator iter(&local_cleanup_list); 6241 while (iter.more_available()) { 6242 HeapRegion* hr = iter.get_next(); 6243 hrp->cleanup(hr); 6244 } 6245 } 6246 6247 prepend_to_freelist(&local_cleanup_list); 6248 decrement_summary_bytes(cl.bytes_freed()); 6249 6250 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 6251 cl.humongous_reclaimed()); 6252 } 6253 6254 // This routine is similar to the above but does not record 6255 // any policy statistics or update free lists; we are abandoning 6256 // the current incremental collection set in preparation of a 6257 // full collection. After the full GC we will start to build up 6258 // the incremental collection set again. 6259 // This is only called when we're doing a full collection 6260 // and is immediately followed by the tearing down of the young list. 6261 6262 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6263 HeapRegion* cur = cs_head; 6264 6265 while (cur != NULL) { 6266 HeapRegion* next = cur->next_in_collection_set(); 6267 assert(cur->in_collection_set(), "bad CS"); 6268 cur->set_next_in_collection_set(NULL); 6269 clear_in_cset(cur); 6270 cur->set_young_index_in_cset(-1); 6271 cur = next; 6272 } 6273 } 6274 6275 void G1CollectedHeap::set_free_regions_coming() { 6276 if (G1ConcRegionFreeingVerbose) { 6277 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6278 "setting free regions coming"); 6279 } 6280 6281 assert(!free_regions_coming(), "pre-condition"); 6282 _free_regions_coming = true; 6283 } 6284 6285 void G1CollectedHeap::reset_free_regions_coming() { 6286 assert(free_regions_coming(), "pre-condition"); 6287 6288 { 6289 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6290 _free_regions_coming = false; 6291 SecondaryFreeList_lock->notify_all(); 6292 } 6293 6294 if (G1ConcRegionFreeingVerbose) { 6295 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6296 "reset free regions coming"); 6297 } 6298 } 6299 6300 void G1CollectedHeap::wait_while_free_regions_coming() { 6301 // Most of the time we won't have to wait, so let's do a quick test 6302 // first before we take the lock. 6303 if (!free_regions_coming()) { 6304 return; 6305 } 6306 6307 if (G1ConcRegionFreeingVerbose) { 6308 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6309 "waiting for free regions"); 6310 } 6311 6312 { 6313 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6314 while (free_regions_coming()) { 6315 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6316 } 6317 } 6318 6319 if (G1ConcRegionFreeingVerbose) { 6320 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6321 "done waiting for free regions"); 6322 } 6323 } 6324 6325 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 6326 return _allocator->is_retained_old_region(hr); 6327 } 6328 6329 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6330 _young_list->push_region(hr); 6331 } 6332 6333 class NoYoungRegionsClosure: public HeapRegionClosure { 6334 private: 6335 bool _success; 6336 public: 6337 NoYoungRegionsClosure() : _success(true) { } 6338 bool doHeapRegion(HeapRegion* r) { 6339 if (r->is_young()) { 6340 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 6341 p2i(r->bottom()), p2i(r->end())); 6342 _success = false; 6343 } 6344 return false; 6345 } 6346 bool success() { return _success; } 6347 }; 6348 6349 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6350 bool ret = _young_list->check_list_empty(check_sample); 6351 6352 if (check_heap) { 6353 NoYoungRegionsClosure closure; 6354 heap_region_iterate(&closure); 6355 ret = ret && closure.success(); 6356 } 6357 6358 return ret; 6359 } 6360 6361 class TearDownRegionSetsClosure : public HeapRegionClosure { 6362 private: 6363 HeapRegionSet *_old_set; 6364 6365 public: 6366 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6367 6368 bool doHeapRegion(HeapRegion* r) { 6369 if (r->is_old()) { 6370 _old_set->remove(r); 6371 } else { 6372 // We ignore free regions, we'll empty the free list afterwards. 6373 // We ignore young regions, we'll empty the young list afterwards. 6374 // We ignore humongous regions, we're not tearing down the 6375 // humongous regions set. 6376 assert(r->is_free() || r->is_young() || r->is_humongous(), 6377 "it cannot be another type"); 6378 } 6379 return false; 6380 } 6381 6382 ~TearDownRegionSetsClosure() { 6383 assert(_old_set->is_empty(), "post-condition"); 6384 } 6385 }; 6386 6387 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6388 assert_at_safepoint(true /* should_be_vm_thread */); 6389 6390 if (!free_list_only) { 6391 TearDownRegionSetsClosure cl(&_old_set); 6392 heap_region_iterate(&cl); 6393 6394 // Note that emptying the _young_list is postponed and instead done as 6395 // the first step when rebuilding the regions sets again. The reason for 6396 // this is that during a full GC string deduplication needs to know if 6397 // a collected region was young or old when the full GC was initiated. 6398 } 6399 _hrm.remove_all_free_regions(); 6400 } 6401 6402 void G1CollectedHeap::increase_used(size_t bytes) { 6403 _summary_bytes_used += bytes; 6404 } 6405 6406 void G1CollectedHeap::decrease_used(size_t bytes) { 6407 assert(_summary_bytes_used >= bytes, 6408 err_msg("invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 6409 _summary_bytes_used, bytes)); 6410 _summary_bytes_used -= bytes; 6411 } 6412 6413 void G1CollectedHeap::set_used(size_t bytes) { 6414 _summary_bytes_used = bytes; 6415 } 6416 6417 class RebuildRegionSetsClosure : public HeapRegionClosure { 6418 private: 6419 bool _free_list_only; 6420 HeapRegionSet* _old_set; 6421 HeapRegionManager* _hrm; 6422 size_t _total_used; 6423 6424 public: 6425 RebuildRegionSetsClosure(bool free_list_only, 6426 HeapRegionSet* old_set, HeapRegionManager* hrm) : 6427 _free_list_only(free_list_only), 6428 _old_set(old_set), _hrm(hrm), _total_used(0) { 6429 assert(_hrm->num_free_regions() == 0, "pre-condition"); 6430 if (!free_list_only) { 6431 assert(_old_set->is_empty(), "pre-condition"); 6432 } 6433 } 6434 6435 bool doHeapRegion(HeapRegion* r) { 6436 if (r->is_continues_humongous()) { 6437 return false; 6438 } 6439 6440 if (r->is_empty()) { 6441 // Add free regions to the free list 6442 r->set_free(); 6443 r->set_allocation_context(AllocationContext::system()); 6444 _hrm->insert_into_free_list(r); 6445 } else if (!_free_list_only) { 6446 assert(!r->is_young(), "we should not come across young regions"); 6447 6448 if (r->is_humongous()) { 6449 // We ignore humongous regions. We left the humongous set unchanged. 6450 } else { 6451 // Objects that were compacted would have ended up on regions 6452 // that were previously old or free. Archive regions (which are 6453 // old) will not have been touched. 6454 assert(r->is_free() || r->is_old(), "invariant"); 6455 // We now consider them old, so register as such. Leave 6456 // archive regions set that way, however, while still adding 6457 // them to the old set. 6458 if (!r->is_archive()) { 6459 r->set_old(); 6460 } 6461 _old_set->add(r); 6462 } 6463 _total_used += r->used(); 6464 } 6465 6466 return false; 6467 } 6468 6469 size_t total_used() { 6470 return _total_used; 6471 } 6472 }; 6473 6474 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6475 assert_at_safepoint(true /* should_be_vm_thread */); 6476 6477 if (!free_list_only) { 6478 _young_list->empty_list(); 6479 } 6480 6481 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 6482 heap_region_iterate(&cl); 6483 6484 if (!free_list_only) { 6485 set_used(cl.total_used()); 6486 if (_archive_allocator != NULL) { 6487 _archive_allocator->clear_used(); 6488 } 6489 } 6490 assert(used_unlocked() == recalculate_used(), 6491 err_msg("inconsistent used_unlocked(), " 6492 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 6493 used_unlocked(), recalculate_used())); 6494 } 6495 6496 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6497 _refine_cte_cl->set_concurrent(concurrent); 6498 } 6499 6500 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6501 HeapRegion* hr = heap_region_containing(p); 6502 return hr->is_in(p); 6503 } 6504 6505 // Methods for the mutator alloc region 6506 6507 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6508 bool force) { 6509 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6510 assert(!force || g1_policy()->can_expand_young_list(), 6511 "if force is true we should be able to expand the young list"); 6512 bool young_list_full = g1_policy()->is_young_list_full(); 6513 if (force || !young_list_full) { 6514 HeapRegion* new_alloc_region = new_region(word_size, 6515 false /* is_old */, 6516 false /* do_expand */); 6517 if (new_alloc_region != NULL) { 6518 set_region_short_lived_locked(new_alloc_region); 6519 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6520 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6521 return new_alloc_region; 6522 } 6523 } 6524 return NULL; 6525 } 6526 6527 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6528 size_t allocated_bytes) { 6529 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6530 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 6531 6532 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6533 increase_used(allocated_bytes); 6534 _hr_printer.retire(alloc_region); 6535 // We update the eden sizes here, when the region is retired, 6536 // instead of when it's allocated, since this is the point that its 6537 // used space has been recored in _summary_bytes_used. 6538 g1mm()->update_eden_size(); 6539 } 6540 6541 // Methods for the GC alloc regions 6542 6543 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6544 uint count, 6545 InCSetState dest) { 6546 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6547 6548 if (count < g1_policy()->max_regions(dest)) { 6549 const bool is_survivor = (dest.is_young()); 6550 HeapRegion* new_alloc_region = new_region(word_size, 6551 !is_survivor, 6552 true /* do_expand */); 6553 if (new_alloc_region != NULL) { 6554 // We really only need to do this for old regions given that we 6555 // should never scan survivors. But it doesn't hurt to do it 6556 // for survivors too. 6557 new_alloc_region->record_timestamp(); 6558 if (is_survivor) { 6559 new_alloc_region->set_survivor(); 6560 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6561 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6562 } else { 6563 new_alloc_region->set_old(); 6564 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6565 check_bitmaps("Old Region Allocation", new_alloc_region); 6566 } 6567 bool during_im = collector_state()->during_initial_mark_pause(); 6568 new_alloc_region->note_start_of_copying(during_im); 6569 return new_alloc_region; 6570 } 6571 } 6572 return NULL; 6573 } 6574 6575 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6576 size_t allocated_bytes, 6577 InCSetState dest) { 6578 bool during_im = collector_state()->during_initial_mark_pause(); 6579 alloc_region->note_end_of_copying(during_im); 6580 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6581 if (dest.is_young()) { 6582 young_list()->add_survivor_region(alloc_region); 6583 } else { 6584 _old_set.add(alloc_region); 6585 } 6586 _hr_printer.retire(alloc_region); 6587 } 6588 6589 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 6590 bool expanded = false; 6591 uint index = _hrm.find_highest_free(&expanded); 6592 6593 if (index != G1_NO_HRM_INDEX) { 6594 if (expanded) { 6595 ergo_verbose1(ErgoHeapSizing, 6596 "attempt heap expansion", 6597 ergo_format_reason("requested address range outside heap bounds") 6598 ergo_format_byte("region size"), 6599 HeapRegion::GrainWords * HeapWordSize); 6600 } 6601 _hrm.allocate_free_regions_starting_at(index, 1); 6602 return region_at(index); 6603 } 6604 return NULL; 6605 } 6606 6607 // Heap region set verification 6608 6609 class VerifyRegionListsClosure : public HeapRegionClosure { 6610 private: 6611 HeapRegionSet* _old_set; 6612 HeapRegionSet* _humongous_set; 6613 HeapRegionManager* _hrm; 6614 6615 public: 6616 HeapRegionSetCount _old_count; 6617 HeapRegionSetCount _humongous_count; 6618 HeapRegionSetCount _free_count; 6619 6620 VerifyRegionListsClosure(HeapRegionSet* old_set, 6621 HeapRegionSet* humongous_set, 6622 HeapRegionManager* hrm) : 6623 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm), 6624 _old_count(), _humongous_count(), _free_count(){ } 6625 6626 bool doHeapRegion(HeapRegion* hr) { 6627 if (hr->is_continues_humongous()) { 6628 return false; 6629 } 6630 6631 if (hr->is_young()) { 6632 // TODO 6633 } else if (hr->is_starts_humongous()) { 6634 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index())); 6635 _humongous_count.increment(1u, hr->capacity()); 6636 } else if (hr->is_empty()) { 6637 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index())); 6638 _free_count.increment(1u, hr->capacity()); 6639 } else if (hr->is_old()) { 6640 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index())); 6641 _old_count.increment(1u, hr->capacity()); 6642 } else { 6643 // There are no other valid region types. Check for one invalid 6644 // one we can identify: pinned without old or humongous set. 6645 assert(!hr->is_pinned(), err_msg("Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index())); 6646 ShouldNotReachHere(); 6647 } 6648 return false; 6649 } 6650 6651 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) { 6652 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 6653 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6654 old_set->total_capacity_bytes(), _old_count.capacity())); 6655 6656 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 6657 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6658 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 6659 6660 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())); 6661 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6662 free_list->total_capacity_bytes(), _free_count.capacity())); 6663 } 6664 }; 6665 6666 void G1CollectedHeap::verify_region_sets() { 6667 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6668 6669 // First, check the explicit lists. 6670 _hrm.verify(); 6671 { 6672 // Given that a concurrent operation might be adding regions to 6673 // the secondary free list we have to take the lock before 6674 // verifying it. 6675 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6676 _secondary_free_list.verify_list(); 6677 } 6678 6679 // If a concurrent region freeing operation is in progress it will 6680 // be difficult to correctly attributed any free regions we come 6681 // across to the correct free list given that they might belong to 6682 // one of several (free_list, secondary_free_list, any local lists, 6683 // etc.). So, if that's the case we will skip the rest of the 6684 // verification operation. Alternatively, waiting for the concurrent 6685 // operation to complete will have a non-trivial effect on the GC's 6686 // operation (no concurrent operation will last longer than the 6687 // interval between two calls to verification) and it might hide 6688 // any issues that we would like to catch during testing. 6689 if (free_regions_coming()) { 6690 return; 6691 } 6692 6693 // Make sure we append the secondary_free_list on the free_list so 6694 // that all free regions we will come across can be safely 6695 // attributed to the free_list. 6696 append_secondary_free_list_if_not_empty_with_lock(); 6697 6698 // Finally, make sure that the region accounting in the lists is 6699 // consistent with what we see in the heap. 6700 6701 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm); 6702 heap_region_iterate(&cl); 6703 cl.verify_counts(&_old_set, &_humongous_set, &_hrm); 6704 } 6705 6706 // Optimized nmethod scanning 6707 6708 class RegisterNMethodOopClosure: public OopClosure { 6709 G1CollectedHeap* _g1h; 6710 nmethod* _nm; 6711 6712 template <class T> void do_oop_work(T* p) { 6713 T heap_oop = oopDesc::load_heap_oop(p); 6714 if (!oopDesc::is_null(heap_oop)) { 6715 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6716 HeapRegion* hr = _g1h->heap_region_containing(obj); 6717 assert(!hr->is_continues_humongous(), 6718 err_msg("trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 6719 " starting at " HR_FORMAT, 6720 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6721 6722 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 6723 hr->add_strong_code_root_locked(_nm); 6724 } 6725 } 6726 6727 public: 6728 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6729 _g1h(g1h), _nm(nm) {} 6730 6731 void do_oop(oop* p) { do_oop_work(p); } 6732 void do_oop(narrowOop* p) { do_oop_work(p); } 6733 }; 6734 6735 class UnregisterNMethodOopClosure: public OopClosure { 6736 G1CollectedHeap* _g1h; 6737 nmethod* _nm; 6738 6739 template <class T> void do_oop_work(T* p) { 6740 T heap_oop = oopDesc::load_heap_oop(p); 6741 if (!oopDesc::is_null(heap_oop)) { 6742 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6743 HeapRegion* hr = _g1h->heap_region_containing(obj); 6744 assert(!hr->is_continues_humongous(), 6745 err_msg("trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 6746 " starting at " HR_FORMAT, 6747 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6748 6749 hr->remove_strong_code_root(_nm); 6750 } 6751 } 6752 6753 public: 6754 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6755 _g1h(g1h), _nm(nm) {} 6756 6757 void do_oop(oop* p) { do_oop_work(p); } 6758 void do_oop(narrowOop* p) { do_oop_work(p); } 6759 }; 6760 6761 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6762 CollectedHeap::register_nmethod(nm); 6763 6764 guarantee(nm != NULL, "sanity"); 6765 RegisterNMethodOopClosure reg_cl(this, nm); 6766 nm->oops_do(®_cl); 6767 } 6768 6769 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6770 CollectedHeap::unregister_nmethod(nm); 6771 6772 guarantee(nm != NULL, "sanity"); 6773 UnregisterNMethodOopClosure reg_cl(this, nm); 6774 nm->oops_do(®_cl, true); 6775 } 6776 6777 void G1CollectedHeap::purge_code_root_memory() { 6778 double purge_start = os::elapsedTime(); 6779 G1CodeRootSet::purge(); 6780 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6781 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6782 } 6783 6784 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6785 G1CollectedHeap* _g1h; 6786 6787 public: 6788 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6789 _g1h(g1h) {} 6790 6791 void do_code_blob(CodeBlob* cb) { 6792 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6793 if (nm == NULL) { 6794 return; 6795 } 6796 6797 if (ScavengeRootsInCode) { 6798 _g1h->register_nmethod(nm); 6799 } 6800 } 6801 }; 6802 6803 void G1CollectedHeap::rebuild_strong_code_roots() { 6804 RebuildStrongCodeRootClosure blob_cl(this); 6805 CodeCache::blobs_do(&blob_cl); 6806 }