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