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_evac_stats(YoungPLABSize, PLABWeight), 1948 _old_evac_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 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 3508 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 3509 stats->unused(), stats->used(), stats->region_end_waste(), 3510 stats->regions_filled(), stats->direct_allocated(), 3511 stats->failure_used(), stats->failure_waste()); 3512 } 3513 3514 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 3515 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 3516 gc_tracer->report_gc_heap_summary(when, heap_summary); 3517 3518 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 3519 gc_tracer->report_metaspace_summary(when, metaspace_summary); 3520 } 3521 3522 3523 G1CollectedHeap* G1CollectedHeap::heap() { 3524 CollectedHeap* heap = Universe::heap(); 3525 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 3526 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); 3527 return (G1CollectedHeap*)heap; 3528 } 3529 3530 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3531 // always_do_update_barrier = false; 3532 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3533 // Fill TLAB's and such 3534 accumulate_statistics_all_tlabs(); 3535 ensure_parsability(true); 3536 3537 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3538 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3539 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3540 } 3541 } 3542 3543 void G1CollectedHeap::gc_epilogue(bool full) { 3544 3545 if (G1SummarizeRSetStats && 3546 (G1SummarizeRSetStatsPeriod > 0) && 3547 // we are at the end of the GC. Total collections has already been increased. 3548 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3549 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3550 } 3551 3552 // FIXME: what is this about? 3553 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3554 // is set. 3555 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3556 "derived pointer present")); 3557 // always_do_update_barrier = true; 3558 3559 resize_all_tlabs(); 3560 allocation_context_stats().update(full); 3561 3562 // We have just completed a GC. Update the soft reference 3563 // policy with the new heap occupancy 3564 Universe::update_heap_info_at_gc(); 3565 } 3566 3567 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3568 uint gc_count_before, 3569 bool* succeeded, 3570 GCCause::Cause gc_cause) { 3571 assert_heap_not_locked_and_not_at_safepoint(); 3572 g1_policy()->record_stop_world_start(); 3573 VM_G1IncCollectionPause op(gc_count_before, 3574 word_size, 3575 false, /* should_initiate_conc_mark */ 3576 g1_policy()->max_pause_time_ms(), 3577 gc_cause); 3578 3579 op.set_allocation_context(AllocationContext::current()); 3580 VMThread::execute(&op); 3581 3582 HeapWord* result = op.result(); 3583 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3584 assert(result == NULL || ret_succeeded, 3585 "the result should be NULL if the VM did not succeed"); 3586 *succeeded = ret_succeeded; 3587 3588 assert_heap_not_locked(); 3589 return result; 3590 } 3591 3592 void 3593 G1CollectedHeap::doConcurrentMark() { 3594 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3595 if (!_cmThread->in_progress()) { 3596 _cmThread->set_started(); 3597 CGC_lock->notify(); 3598 } 3599 } 3600 3601 size_t G1CollectedHeap::pending_card_num() { 3602 size_t extra_cards = 0; 3603 JavaThread *curr = Threads::first(); 3604 while (curr != NULL) { 3605 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3606 extra_cards += dcq.size(); 3607 curr = curr->next(); 3608 } 3609 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3610 size_t buffer_size = dcqs.buffer_size(); 3611 size_t buffer_num = dcqs.completed_buffers_num(); 3612 3613 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3614 // in bytes - not the number of 'entries'. We need to convert 3615 // into a number of cards. 3616 return (buffer_size * buffer_num + extra_cards) / oopSize; 3617 } 3618 3619 size_t G1CollectedHeap::cards_scanned() { 3620 return g1_rem_set()->cardsScanned(); 3621 } 3622 3623 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3624 private: 3625 size_t _total_humongous; 3626 size_t _candidate_humongous; 3627 3628 DirtyCardQueue _dcq; 3629 3630 // We don't nominate objects with many remembered set entries, on 3631 // the assumption that such objects are likely still live. 3632 bool is_remset_small(HeapRegion* region) const { 3633 HeapRegionRemSet* const rset = region->rem_set(); 3634 return G1EagerReclaimHumongousObjectsWithStaleRefs 3635 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) 3636 : rset->is_empty(); 3637 } 3638 3639 bool is_typeArray_region(HeapRegion* region) const { 3640 return oop(region->bottom())->is_typeArray(); 3641 } 3642 3643 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { 3644 assert(region->is_starts_humongous(), "Must start a humongous object"); 3645 3646 // Candidate selection must satisfy the following constraints 3647 // while concurrent marking is in progress: 3648 // 3649 // * In order to maintain SATB invariants, an object must not be 3650 // reclaimed if it was allocated before the start of marking and 3651 // has not had its references scanned. Such an object must have 3652 // its references (including type metadata) scanned to ensure no 3653 // live objects are missed by the marking process. Objects 3654 // allocated after the start of concurrent marking don't need to 3655 // be scanned. 3656 // 3657 // * An object must not be reclaimed if it is on the concurrent 3658 // mark stack. Objects allocated after the start of concurrent 3659 // marking are never pushed on the mark stack. 3660 // 3661 // Nominating only objects allocated after the start of concurrent 3662 // marking is sufficient to meet both constraints. This may miss 3663 // some objects that satisfy the constraints, but the marking data 3664 // structures don't support efficiently performing the needed 3665 // additional tests or scrubbing of the mark stack. 3666 // 3667 // However, we presently only nominate is_typeArray() objects. 3668 // A humongous object containing references induces remembered 3669 // set entries on other regions. In order to reclaim such an 3670 // object, those remembered sets would need to be cleaned up. 3671 // 3672 // We also treat is_typeArray() objects specially, allowing them 3673 // to be reclaimed even if allocated before the start of 3674 // concurrent mark. For this we rely on mark stack insertion to 3675 // exclude is_typeArray() objects, preventing reclaiming an object 3676 // that is in the mark stack. We also rely on the metadata for 3677 // such objects to be built-in and so ensured to be kept live. 3678 // Frequent allocation and drop of large binary blobs is an 3679 // important use case for eager reclaim, and this special handling 3680 // may reduce needed headroom. 3681 3682 return is_typeArray_region(region) && is_remset_small(region); 3683 } 3684 3685 public: 3686 RegisterHumongousWithInCSetFastTestClosure() 3687 : _total_humongous(0), 3688 _candidate_humongous(0), 3689 _dcq(&JavaThread::dirty_card_queue_set()) { 3690 } 3691 3692 virtual bool doHeapRegion(HeapRegion* r) { 3693 if (!r->is_starts_humongous()) { 3694 return false; 3695 } 3696 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3697 3698 bool is_candidate = humongous_region_is_candidate(g1h, r); 3699 uint rindex = r->hrm_index(); 3700 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 3701 if (is_candidate) { 3702 _candidate_humongous++; 3703 g1h->register_humongous_region_with_cset(rindex); 3704 // Is_candidate already filters out humongous object with large remembered sets. 3705 // If we have a humongous object with a few remembered sets, we simply flush these 3706 // remembered set entries into the DCQS. That will result in automatic 3707 // re-evaluation of their remembered set entries during the following evacuation 3708 // phase. 3709 if (!r->rem_set()->is_empty()) { 3710 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 3711 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 3712 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 3713 HeapRegionRemSetIterator hrrs(r->rem_set()); 3714 size_t card_index; 3715 while (hrrs.has_next(card_index)) { 3716 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 3717 // The remembered set might contain references to already freed 3718 // regions. Filter out such entries to avoid failing card table 3719 // verification. 3720 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) { 3721 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 3722 *card_ptr = CardTableModRefBS::dirty_card_val(); 3723 _dcq.enqueue(card_ptr); 3724 } 3725 } 3726 } 3727 r->rem_set()->clear_locked(); 3728 } 3729 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 3730 } 3731 _total_humongous++; 3732 3733 return false; 3734 } 3735 3736 size_t total_humongous() const { return _total_humongous; } 3737 size_t candidate_humongous() const { return _candidate_humongous; } 3738 3739 void flush_rem_set_entries() { _dcq.flush(); } 3740 }; 3741 3742 void G1CollectedHeap::register_humongous_regions_with_cset() { 3743 if (!G1EagerReclaimHumongousObjects) { 3744 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 3745 return; 3746 } 3747 double time = os::elapsed_counter(); 3748 3749 // Collect reclaim candidate information and register candidates with cset. 3750 RegisterHumongousWithInCSetFastTestClosure cl; 3751 heap_region_iterate(&cl); 3752 3753 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 3754 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 3755 cl.total_humongous(), 3756 cl.candidate_humongous()); 3757 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3758 3759 // Finally flush all remembered set entries to re-check into the global DCQS. 3760 cl.flush_rem_set_entries(); 3761 } 3762 3763 void 3764 G1CollectedHeap::setup_surviving_young_words() { 3765 assert(_surviving_young_words == NULL, "pre-condition"); 3766 uint array_length = g1_policy()->young_cset_region_length(); 3767 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3768 if (_surviving_young_words == NULL) { 3769 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3770 "Not enough space for young surv words summary."); 3771 } 3772 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3773 #ifdef ASSERT 3774 for (uint i = 0; i < array_length; ++i) { 3775 assert( _surviving_young_words[i] == 0, "memset above" ); 3776 } 3777 #endif // !ASSERT 3778 } 3779 3780 void 3781 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3782 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3783 uint array_length = g1_policy()->young_cset_region_length(); 3784 for (uint i = 0; i < array_length; ++i) { 3785 _surviving_young_words[i] += surv_young_words[i]; 3786 } 3787 } 3788 3789 void 3790 G1CollectedHeap::cleanup_surviving_young_words() { 3791 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3792 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words); 3793 _surviving_young_words = NULL; 3794 } 3795 3796 #ifdef ASSERT 3797 class VerifyCSetClosure: public HeapRegionClosure { 3798 public: 3799 bool doHeapRegion(HeapRegion* hr) { 3800 // Here we check that the CSet region's RSet is ready for parallel 3801 // iteration. The fields that we'll verify are only manipulated 3802 // when the region is part of a CSet and is collected. Afterwards, 3803 // we reset these fields when we clear the region's RSet (when the 3804 // region is freed) so they are ready when the region is 3805 // re-allocated. The only exception to this is if there's an 3806 // evacuation failure and instead of freeing the region we leave 3807 // it in the heap. In that case, we reset these fields during 3808 // evacuation failure handling. 3809 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3810 3811 // Here's a good place to add any other checks we'd like to 3812 // perform on CSet regions. 3813 return false; 3814 } 3815 }; 3816 #endif // ASSERT 3817 3818 uint G1CollectedHeap::num_task_queues() const { 3819 return _task_queues->size(); 3820 } 3821 3822 #if TASKQUEUE_STATS 3823 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3824 st->print_raw_cr("GC Task Stats"); 3825 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3826 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3827 } 3828 3829 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3830 print_taskqueue_stats_hdr(st); 3831 3832 TaskQueueStats totals; 3833 const uint n = num_task_queues(); 3834 for (uint i = 0; i < n; ++i) { 3835 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 3836 totals += task_queue(i)->stats; 3837 } 3838 st->print_raw("tot "); totals.print(st); st->cr(); 3839 3840 DEBUG_ONLY(totals.verify()); 3841 } 3842 3843 void G1CollectedHeap::reset_taskqueue_stats() { 3844 const uint n = num_task_queues(); 3845 for (uint i = 0; i < n; ++i) { 3846 task_queue(i)->stats.reset(); 3847 } 3848 } 3849 #endif // TASKQUEUE_STATS 3850 3851 void G1CollectedHeap::log_gc_header() { 3852 if (!G1Log::fine()) { 3853 return; 3854 } 3855 3856 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id()); 3857 3858 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3859 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)") 3860 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3861 3862 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3863 } 3864 3865 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3866 if (!G1Log::fine()) { 3867 return; 3868 } 3869 3870 if (G1Log::finer()) { 3871 if (evacuation_failed()) { 3872 gclog_or_tty->print(" (to-space exhausted)"); 3873 } 3874 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3875 g1_policy()->phase_times()->note_gc_end(); 3876 g1_policy()->phase_times()->print(pause_time_sec); 3877 g1_policy()->print_detailed_heap_transition(); 3878 } else { 3879 if (evacuation_failed()) { 3880 gclog_or_tty->print("--"); 3881 } 3882 g1_policy()->print_heap_transition(); 3883 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3884 } 3885 gclog_or_tty->flush(); 3886 } 3887 3888 void G1CollectedHeap::wait_for_root_region_scanning() { 3889 double scan_wait_start = os::elapsedTime(); 3890 // We have to wait until the CM threads finish scanning the 3891 // root regions as it's the only way to ensure that all the 3892 // objects on them have been correctly scanned before we start 3893 // moving them during the GC. 3894 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3895 double wait_time_ms = 0.0; 3896 if (waited) { 3897 double scan_wait_end = os::elapsedTime(); 3898 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3899 } 3900 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3901 } 3902 3903 bool 3904 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3905 assert_at_safepoint(true /* should_be_vm_thread */); 3906 guarantee(!is_gc_active(), "collection is not reentrant"); 3907 3908 if (GC_locker::check_active_before_gc()) { 3909 return false; 3910 } 3911 3912 _gc_timer_stw->register_gc_start(); 3913 3914 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3915 3916 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3917 ResourceMark rm; 3918 3919 wait_for_root_region_scanning(); 3920 3921 G1Log::update_level(); 3922 print_heap_before_gc(); 3923 trace_heap_before_gc(_gc_tracer_stw); 3924 3925 verify_region_sets_optional(); 3926 verify_dirty_young_regions(); 3927 3928 // This call will decide whether this pause is an initial-mark 3929 // pause. If it is, during_initial_mark_pause() will return true 3930 // for the duration of this pause. 3931 g1_policy()->decide_on_conc_mark_initiation(); 3932 3933 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3934 assert(!collector_state()->during_initial_mark_pause() || 3935 collector_state()->gcs_are_young(), "sanity"); 3936 3937 // We also do not allow mixed GCs during marking. 3938 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity"); 3939 3940 // Record whether this pause is an initial mark. When the current 3941 // thread has completed its logging output and it's safe to signal 3942 // the CM thread, the flag's value in the policy has been reset. 3943 bool should_start_conc_mark = collector_state()->during_initial_mark_pause(); 3944 3945 // Inner scope for scope based logging, timers, and stats collection 3946 { 3947 EvacuationInfo evacuation_info; 3948 3949 if (collector_state()->during_initial_mark_pause()) { 3950 // We are about to start a marking cycle, so we increment the 3951 // full collection counter. 3952 increment_old_marking_cycles_started(); 3953 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3954 } 3955 3956 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 3957 3958 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3959 3960 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 3961 workers()->active_workers(), 3962 Threads::number_of_non_daemon_threads()); 3963 workers()->set_active_workers(active_workers); 3964 3965 double pause_start_sec = os::elapsedTime(); 3966 g1_policy()->phase_times()->note_gc_start(active_workers, collector_state()->mark_in_progress()); 3967 log_gc_header(); 3968 3969 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3970 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3971 3972 // If the secondary_free_list is not empty, append it to the 3973 // free_list. No need to wait for the cleanup operation to finish; 3974 // the region allocation code will check the secondary_free_list 3975 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3976 // set, skip this step so that the region allocation code has to 3977 // get entries from the secondary_free_list. 3978 if (!G1StressConcRegionFreeing) { 3979 append_secondary_free_list_if_not_empty_with_lock(); 3980 } 3981 3982 assert(check_young_list_well_formed(), "young list should be well formed"); 3983 3984 // Don't dynamically change the number of GC threads this early. A value of 3985 // 0 is used to indicate serial work. When parallel work is done, 3986 // it will be set. 3987 3988 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3989 IsGCActiveMark x; 3990 3991 gc_prologue(false); 3992 increment_total_collections(false /* full gc */); 3993 increment_gc_time_stamp(); 3994 3995 verify_before_gc(); 3996 3997 check_bitmaps("GC Start"); 3998 3999 COMPILER2_PRESENT(DerivedPointerTable::clear()); 4000 4001 // Please see comment in g1CollectedHeap.hpp and 4002 // G1CollectedHeap::ref_processing_init() to see how 4003 // reference processing currently works in G1. 4004 4005 // Enable discovery in the STW reference processor 4006 ref_processor_stw()->enable_discovery(); 4007 4008 { 4009 // We want to temporarily turn off discovery by the 4010 // CM ref processor, if necessary, and turn it back on 4011 // on again later if we do. Using a scoped 4012 // NoRefDiscovery object will do this. 4013 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 4014 4015 // Forget the current alloc region (we might even choose it to be part 4016 // of the collection set!). 4017 _allocator->release_mutator_alloc_region(); 4018 4019 // We should call this after we retire the mutator alloc 4020 // region(s) so that all the ALLOC / RETIRE events are generated 4021 // before the start GC event. 4022 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 4023 4024 // This timing is only used by the ergonomics to handle our pause target. 4025 // It is unclear why this should not include the full pause. We will 4026 // investigate this in CR 7178365. 4027 // 4028 // Preserving the old comment here if that helps the investigation: 4029 // 4030 // The elapsed time induced by the start time below deliberately elides 4031 // the possible verification above. 4032 double sample_start_time_sec = os::elapsedTime(); 4033 4034 #if YOUNG_LIST_VERBOSE 4035 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 4036 _young_list->print(); 4037 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4038 #endif // YOUNG_LIST_VERBOSE 4039 4040 g1_policy()->record_collection_pause_start(sample_start_time_sec); 4041 4042 #if YOUNG_LIST_VERBOSE 4043 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 4044 _young_list->print(); 4045 #endif // YOUNG_LIST_VERBOSE 4046 4047 if (collector_state()->during_initial_mark_pause()) { 4048 concurrent_mark()->checkpointRootsInitialPre(); 4049 } 4050 4051 #if YOUNG_LIST_VERBOSE 4052 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 4053 _young_list->print(); 4054 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4055 #endif // YOUNG_LIST_VERBOSE 4056 4057 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 4058 4059 register_humongous_regions_with_cset(); 4060 4061 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table."); 4062 4063 _cm->note_start_of_gc(); 4064 // We call this after finalize_cset() to 4065 // ensure that the CSet has been finalized. 4066 _cm->verify_no_cset_oops(); 4067 4068 if (_hr_printer.is_active()) { 4069 HeapRegion* hr = g1_policy()->collection_set(); 4070 while (hr != NULL) { 4071 _hr_printer.cset(hr); 4072 hr = hr->next_in_collection_set(); 4073 } 4074 } 4075 4076 #ifdef ASSERT 4077 VerifyCSetClosure cl; 4078 collection_set_iterate(&cl); 4079 #endif // ASSERT 4080 4081 setup_surviving_young_words(); 4082 4083 // Initialize the GC alloc regions. 4084 _allocator->init_gc_alloc_regions(evacuation_info); 4085 4086 // Actually do the work... 4087 evacuate_collection_set(evacuation_info); 4088 4089 free_collection_set(g1_policy()->collection_set(), evacuation_info); 4090 4091 eagerly_reclaim_humongous_regions(); 4092 4093 g1_policy()->clear_collection_set(); 4094 4095 cleanup_surviving_young_words(); 4096 4097 // Start a new incremental collection set for the next pause. 4098 g1_policy()->start_incremental_cset_building(); 4099 4100 clear_cset_fast_test(); 4101 4102 _young_list->reset_sampled_info(); 4103 4104 // Don't check the whole heap at this point as the 4105 // GC alloc regions from this pause have been tagged 4106 // as survivors and moved on to the survivor list. 4107 // Survivor regions will fail the !is_young() check. 4108 assert(check_young_list_empty(false /* check_heap */), 4109 "young list should be empty"); 4110 4111 #if YOUNG_LIST_VERBOSE 4112 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 4113 _young_list->print(); 4114 #endif // YOUNG_LIST_VERBOSE 4115 4116 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 4117 _young_list->first_survivor_region(), 4118 _young_list->last_survivor_region()); 4119 4120 _young_list->reset_auxilary_lists(); 4121 4122 if (evacuation_failed()) { 4123 set_used(recalculate_used()); 4124 if (_archive_allocator != NULL) { 4125 _archive_allocator->clear_used(); 4126 } 4127 for (uint i = 0; i < ParallelGCThreads; i++) { 4128 if (_evacuation_failed_info_array[i].has_failed()) { 4129 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 4130 } 4131 } 4132 } else { 4133 // The "used" of the the collection set have already been subtracted 4134 // when they were freed. Add in the bytes evacuated. 4135 increase_used(g1_policy()->bytes_copied_during_gc()); 4136 } 4137 4138 if (collector_state()->during_initial_mark_pause()) { 4139 // We have to do this before we notify the CM threads that 4140 // they can start working to make sure that all the 4141 // appropriate initialization is done on the CM object. 4142 concurrent_mark()->checkpointRootsInitialPost(); 4143 collector_state()->set_mark_in_progress(true); 4144 // Note that we don't actually trigger the CM thread at 4145 // this point. We do that later when we're sure that 4146 // the current thread has completed its logging output. 4147 } 4148 4149 allocate_dummy_regions(); 4150 4151 #if YOUNG_LIST_VERBOSE 4152 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 4153 _young_list->print(); 4154 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4155 #endif // YOUNG_LIST_VERBOSE 4156 4157 _allocator->init_mutator_alloc_region(); 4158 4159 { 4160 size_t expand_bytes = g1_policy()->expansion_amount(); 4161 if (expand_bytes > 0) { 4162 size_t bytes_before = capacity(); 4163 // No need for an ergo verbose message here, 4164 // expansion_amount() does this when it returns a value > 0. 4165 if (!expand(expand_bytes)) { 4166 // We failed to expand the heap. Cannot do anything about it. 4167 } 4168 } 4169 } 4170 4171 // We redo the verification but now wrt to the new CSet which 4172 // has just got initialized after the previous CSet was freed. 4173 _cm->verify_no_cset_oops(); 4174 _cm->note_end_of_gc(); 4175 4176 // This timing is only used by the ergonomics to handle our pause target. 4177 // It is unclear why this should not include the full pause. We will 4178 // investigate this in CR 7178365. 4179 double sample_end_time_sec = os::elapsedTime(); 4180 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 4181 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 4182 4183 MemoryService::track_memory_usage(); 4184 4185 // In prepare_for_verify() below we'll need to scan the deferred 4186 // update buffers to bring the RSets up-to-date if 4187 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4188 // the update buffers we'll probably need to scan cards on the 4189 // regions we just allocated to (i.e., the GC alloc 4190 // regions). However, during the last GC we called 4191 // set_saved_mark() on all the GC alloc regions, so card 4192 // scanning might skip the [saved_mark_word()...top()] area of 4193 // those regions (i.e., the area we allocated objects into 4194 // during the last GC). But it shouldn't. Given that 4195 // saved_mark_word() is conditional on whether the GC time stamp 4196 // on the region is current or not, by incrementing the GC time 4197 // stamp here we invalidate all the GC time stamps on all the 4198 // regions and saved_mark_word() will simply return top() for 4199 // all the regions. This is a nicer way of ensuring this rather 4200 // than iterating over the regions and fixing them. In fact, the 4201 // GC time stamp increment here also ensures that 4202 // saved_mark_word() will return top() between pauses, i.e., 4203 // during concurrent refinement. So we don't need the 4204 // is_gc_active() check to decided which top to use when 4205 // scanning cards (see CR 7039627). 4206 increment_gc_time_stamp(); 4207 4208 verify_after_gc(); 4209 check_bitmaps("GC End"); 4210 4211 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4212 ref_processor_stw()->verify_no_references_recorded(); 4213 4214 // CM reference discovery will be re-enabled if necessary. 4215 } 4216 4217 // We should do this after we potentially expand the heap so 4218 // that all the COMMIT events are generated before the end GC 4219 // event, and after we retire the GC alloc regions so that all 4220 // RETIRE events are generated before the end GC event. 4221 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4222 4223 #ifdef TRACESPINNING 4224 ParallelTaskTerminator::print_termination_counts(); 4225 #endif 4226 4227 gc_epilogue(false); 4228 } 4229 4230 // Print the remainder of the GC log output. 4231 log_gc_footer(os::elapsedTime() - pause_start_sec); 4232 4233 // It is not yet to safe to tell the concurrent mark to 4234 // start as we have some optional output below. We don't want the 4235 // output from the concurrent mark thread interfering with this 4236 // logging output either. 4237 4238 _hrm.verify_optional(); 4239 verify_region_sets_optional(); 4240 4241 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats()); 4242 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4243 4244 print_heap_after_gc(); 4245 trace_heap_after_gc(_gc_tracer_stw); 4246 4247 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4248 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4249 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4250 // before any GC notifications are raised. 4251 g1mm()->update_sizes(); 4252 4253 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4254 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4255 _gc_timer_stw->register_gc_end(); 4256 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4257 } 4258 // It should now be safe to tell the concurrent mark thread to start 4259 // without its logging output interfering with the logging output 4260 // that came from the pause. 4261 4262 if (should_start_conc_mark) { 4263 // CAUTION: after the doConcurrentMark() call below, 4264 // the concurrent marking thread(s) could be running 4265 // concurrently with us. Make sure that anything after 4266 // this point does not assume that we are the only GC thread 4267 // running. Note: of course, the actual marking work will 4268 // not start until the safepoint itself is released in 4269 // SuspendibleThreadSet::desynchronize(). 4270 doConcurrentMark(); 4271 } 4272 4273 return true; 4274 } 4275 4276 void G1CollectedHeap::remove_self_forwarding_pointers() { 4277 double remove_self_forwards_start = os::elapsedTime(); 4278 4279 G1ParRemoveSelfForwardPtrsTask rsfp_task; 4280 workers()->run_task(&rsfp_task); 4281 4282 // Now restore saved marks, if any. 4283 for (uint i = 0; i < ParallelGCThreads; i++) { 4284 OopAndMarkOopStack& cur = _preserved_objs[i]; 4285 while (!cur.is_empty()) { 4286 OopAndMarkOop elem = cur.pop(); 4287 elem.set_mark(); 4288 } 4289 cur.clear(true); 4290 } 4291 4292 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4293 } 4294 4295 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 4296 if (!_evacuation_failed) { 4297 _evacuation_failed = true; 4298 } 4299 4300 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 4301 4302 // We want to call the "for_promotion_failure" version only in the 4303 // case of a promotion failure. 4304 if (m->must_be_preserved_for_promotion_failure(obj)) { 4305 OopAndMarkOop elem(obj, m); 4306 _preserved_objs[worker_id].push(elem); 4307 } 4308 } 4309 4310 void G1ParCopyHelper::mark_object(oop obj) { 4311 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); 4312 4313 // We know that the object is not moving so it's safe to read its size. 4314 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4315 } 4316 4317 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4318 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4319 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4320 assert(from_obj != to_obj, "should not be self-forwarded"); 4321 4322 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); 4323 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); 4324 4325 // The object might be in the process of being copied by another 4326 // worker so we cannot trust that its to-space image is 4327 // well-formed. So we have to read its size from its from-space 4328 // image which we know should not be changing. 4329 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4330 } 4331 4332 template <class T> 4333 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4334 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4335 _scanned_klass->record_modified_oops(); 4336 } 4337 } 4338 4339 template <G1Barrier barrier, G1Mark do_mark_object> 4340 template <class T> 4341 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4342 T heap_oop = oopDesc::load_heap_oop(p); 4343 4344 if (oopDesc::is_null(heap_oop)) { 4345 return; 4346 } 4347 4348 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4349 4350 assert(_worker_id == _par_scan_state->worker_id(), "sanity"); 4351 4352 const InCSetState state = _g1->in_cset_state(obj); 4353 if (state.is_in_cset()) { 4354 oop forwardee; 4355 markOop m = obj->mark(); 4356 if (m->is_marked()) { 4357 forwardee = (oop) m->decode_pointer(); 4358 } else { 4359 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m); 4360 } 4361 assert(forwardee != NULL, "forwardee should not be NULL"); 4362 oopDesc::encode_store_heap_oop(p, forwardee); 4363 if (do_mark_object != G1MarkNone && forwardee != obj) { 4364 // If the object is self-forwarded we don't need to explicitly 4365 // mark it, the evacuation failure protocol will do so. 4366 mark_forwarded_object(obj, forwardee); 4367 } 4368 4369 if (barrier == G1BarrierKlass) { 4370 do_klass_barrier(p, forwardee); 4371 } 4372 } else { 4373 if (state.is_humongous()) { 4374 _g1->set_humongous_is_live(obj); 4375 } 4376 // The object is not in collection set. If we're a root scanning 4377 // closure during an initial mark pause then attempt to mark the object. 4378 if (do_mark_object == G1MarkFromRoot) { 4379 mark_object(obj); 4380 } 4381 } 4382 } 4383 4384 class G1ParEvacuateFollowersClosure : public VoidClosure { 4385 protected: 4386 G1CollectedHeap* _g1h; 4387 G1ParScanThreadState* _par_scan_state; 4388 RefToScanQueueSet* _queues; 4389 ParallelTaskTerminator* _terminator; 4390 4391 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4392 RefToScanQueueSet* queues() { return _queues; } 4393 ParallelTaskTerminator* terminator() { return _terminator; } 4394 4395 public: 4396 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4397 G1ParScanThreadState* par_scan_state, 4398 RefToScanQueueSet* queues, 4399 ParallelTaskTerminator* terminator) 4400 : _g1h(g1h), _par_scan_state(par_scan_state), 4401 _queues(queues), _terminator(terminator) {} 4402 4403 void do_void(); 4404 4405 private: 4406 inline bool offer_termination(); 4407 }; 4408 4409 bool G1ParEvacuateFollowersClosure::offer_termination() { 4410 G1ParScanThreadState* const pss = par_scan_state(); 4411 pss->start_term_time(); 4412 const bool res = terminator()->offer_termination(); 4413 pss->end_term_time(); 4414 return res; 4415 } 4416 4417 void G1ParEvacuateFollowersClosure::do_void() { 4418 G1ParScanThreadState* const pss = par_scan_state(); 4419 pss->trim_queue(); 4420 do { 4421 pss->steal_and_trim_queue(queues()); 4422 } while (!offer_termination()); 4423 } 4424 4425 class G1KlassScanClosure : public KlassClosure { 4426 G1ParCopyHelper* _closure; 4427 bool _process_only_dirty; 4428 int _count; 4429 public: 4430 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4431 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4432 void do_klass(Klass* klass) { 4433 // If the klass has not been dirtied we know that there's 4434 // no references into the young gen and we can skip it. 4435 if (!_process_only_dirty || klass->has_modified_oops()) { 4436 // Clean the klass since we're going to scavenge all the metadata. 4437 klass->clear_modified_oops(); 4438 4439 // Tell the closure that this klass is the Klass to scavenge 4440 // and is the one to dirty if oops are left pointing into the young gen. 4441 _closure->set_scanned_klass(klass); 4442 4443 klass->oops_do(_closure); 4444 4445 _closure->set_scanned_klass(NULL); 4446 } 4447 _count++; 4448 } 4449 }; 4450 4451 class G1ParTask : public AbstractGangTask { 4452 protected: 4453 G1CollectedHeap* _g1h; 4454 RefToScanQueueSet *_queues; 4455 G1RootProcessor* _root_processor; 4456 ParallelTaskTerminator _terminator; 4457 uint _n_workers; 4458 4459 public: 4460 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 4461 : AbstractGangTask("G1 collection"), 4462 _g1h(g1h), 4463 _queues(task_queues), 4464 _root_processor(root_processor), 4465 _terminator(n_workers, _queues), 4466 _n_workers(n_workers) 4467 {} 4468 4469 RefToScanQueueSet* queues() { return _queues; } 4470 4471 RefToScanQueue *work_queue(int i) { 4472 return queues()->queue(i); 4473 } 4474 4475 ParallelTaskTerminator* terminator() { return &_terminator; } 4476 4477 // Helps out with CLD processing. 4478 // 4479 // During InitialMark we need to: 4480 // 1) Scavenge all CLDs for the young GC. 4481 // 2) Mark all objects directly reachable from strong CLDs. 4482 template <G1Mark do_mark_object> 4483 class G1CLDClosure : public CLDClosure { 4484 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure; 4485 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure; 4486 G1KlassScanClosure _klass_in_cld_closure; 4487 bool _claim; 4488 4489 public: 4490 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure, 4491 bool only_young, bool claim) 4492 : _oop_closure(oop_closure), 4493 _oop_in_klass_closure(oop_closure->g1(), 4494 oop_closure->pss(), 4495 oop_closure->rp()), 4496 _klass_in_cld_closure(&_oop_in_klass_closure, only_young), 4497 _claim(claim) { 4498 4499 } 4500 4501 void do_cld(ClassLoaderData* cld) { 4502 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim); 4503 } 4504 }; 4505 4506 void work(uint worker_id) { 4507 if (worker_id >= _n_workers) return; // no work needed this round 4508 4509 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime()); 4510 4511 { 4512 ResourceMark rm; 4513 HandleMark hm; 4514 4515 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4516 4517 G1ParScanThreadState pss(_g1h, worker_id, rp); 4518 4519 bool only_young = _g1h->collector_state()->gcs_are_young(); 4520 4521 // Non-IM young GC. 4522 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp); 4523 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl, 4524 only_young, // Only process dirty klasses. 4525 false); // No need to claim CLDs. 4526 // IM young GC. 4527 // Strong roots closures. 4528 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp); 4529 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl, 4530 false, // Process all klasses. 4531 true); // Need to claim CLDs. 4532 // Weak roots closures. 4533 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp); 4534 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl, 4535 false, // Process all klasses. 4536 true); // Need to claim CLDs. 4537 4538 OopClosure* strong_root_cl; 4539 OopClosure* weak_root_cl; 4540 CLDClosure* strong_cld_cl; 4541 CLDClosure* weak_cld_cl; 4542 4543 bool trace_metadata = false; 4544 4545 if (_g1h->collector_state()->during_initial_mark_pause()) { 4546 // We also need to mark copied objects. 4547 strong_root_cl = &scan_mark_root_cl; 4548 strong_cld_cl = &scan_mark_cld_cl; 4549 if (ClassUnloadingWithConcurrentMark) { 4550 weak_root_cl = &scan_mark_weak_root_cl; 4551 weak_cld_cl = &scan_mark_weak_cld_cl; 4552 trace_metadata = true; 4553 } else { 4554 weak_root_cl = &scan_mark_root_cl; 4555 weak_cld_cl = &scan_mark_cld_cl; 4556 } 4557 } else { 4558 strong_root_cl = &scan_only_root_cl; 4559 weak_root_cl = &scan_only_root_cl; 4560 strong_cld_cl = &scan_only_cld_cl; 4561 weak_cld_cl = &scan_only_cld_cl; 4562 } 4563 4564 pss.start_strong_roots(); 4565 4566 _root_processor->evacuate_roots(strong_root_cl, 4567 weak_root_cl, 4568 strong_cld_cl, 4569 weak_cld_cl, 4570 trace_metadata, 4571 worker_id); 4572 4573 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4574 _root_processor->scan_remembered_sets(&push_heap_rs_cl, 4575 weak_root_cl, 4576 worker_id); 4577 pss.end_strong_roots(); 4578 4579 { 4580 double start = os::elapsedTime(); 4581 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4582 evac.do_void(); 4583 double elapsed_sec = os::elapsedTime() - start; 4584 double term_sec = pss.term_time(); 4585 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 4586 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 4587 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts()); 4588 } 4589 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4590 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4591 4592 if (PrintTerminationStats) { 4593 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 4594 pss.print_termination_stats(); 4595 } 4596 4597 assert(pss.queue_is_empty(), "should be empty"); 4598 4599 // Close the inner scope so that the ResourceMark and HandleMark 4600 // destructors are executed here and are included as part of the 4601 // "GC Worker Time". 4602 } 4603 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 4604 } 4605 }; 4606 4607 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4608 private: 4609 BoolObjectClosure* _is_alive; 4610 int _initial_string_table_size; 4611 int _initial_symbol_table_size; 4612 4613 bool _process_strings; 4614 int _strings_processed; 4615 int _strings_removed; 4616 4617 bool _process_symbols; 4618 int _symbols_processed; 4619 int _symbols_removed; 4620 4621 public: 4622 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4623 AbstractGangTask("String/Symbol Unlinking"), 4624 _is_alive(is_alive), 4625 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4626 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4627 4628 _initial_string_table_size = StringTable::the_table()->table_size(); 4629 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4630 if (process_strings) { 4631 StringTable::clear_parallel_claimed_index(); 4632 } 4633 if (process_symbols) { 4634 SymbolTable::clear_parallel_claimed_index(); 4635 } 4636 } 4637 4638 ~G1StringSymbolTableUnlinkTask() { 4639 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4640 err_msg("claim value %d after unlink less than initial string table size %d", 4641 StringTable::parallel_claimed_index(), _initial_string_table_size)); 4642 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4643 err_msg("claim value %d after unlink less than initial symbol table size %d", 4644 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 4645 4646 if (G1TraceStringSymbolTableScrubbing) { 4647 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4648 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, " 4649 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed", 4650 strings_processed(), strings_removed(), 4651 symbols_processed(), symbols_removed()); 4652 } 4653 } 4654 4655 void work(uint worker_id) { 4656 int strings_processed = 0; 4657 int strings_removed = 0; 4658 int symbols_processed = 0; 4659 int symbols_removed = 0; 4660 if (_process_strings) { 4661 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4662 Atomic::add(strings_processed, &_strings_processed); 4663 Atomic::add(strings_removed, &_strings_removed); 4664 } 4665 if (_process_symbols) { 4666 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 4667 Atomic::add(symbols_processed, &_symbols_processed); 4668 Atomic::add(symbols_removed, &_symbols_removed); 4669 } 4670 } 4671 4672 size_t strings_processed() const { return (size_t)_strings_processed; } 4673 size_t strings_removed() const { return (size_t)_strings_removed; } 4674 4675 size_t symbols_processed() const { return (size_t)_symbols_processed; } 4676 size_t symbols_removed() const { return (size_t)_symbols_removed; } 4677 }; 4678 4679 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 4680 private: 4681 static Monitor* _lock; 4682 4683 BoolObjectClosure* const _is_alive; 4684 const bool _unloading_occurred; 4685 const uint _num_workers; 4686 4687 // Variables used to claim nmethods. 4688 nmethod* _first_nmethod; 4689 volatile nmethod* _claimed_nmethod; 4690 4691 // The list of nmethods that need to be processed by the second pass. 4692 volatile nmethod* _postponed_list; 4693 volatile uint _num_entered_barrier; 4694 4695 public: 4696 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 4697 _is_alive(is_alive), 4698 _unloading_occurred(unloading_occurred), 4699 _num_workers(num_workers), 4700 _first_nmethod(NULL), 4701 _claimed_nmethod(NULL), 4702 _postponed_list(NULL), 4703 _num_entered_barrier(0) 4704 { 4705 nmethod::increase_unloading_clock(); 4706 // Get first alive nmethod 4707 NMethodIterator iter = NMethodIterator(); 4708 if(iter.next_alive()) { 4709 _first_nmethod = iter.method(); 4710 } 4711 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 4712 } 4713 4714 ~G1CodeCacheUnloadingTask() { 4715 CodeCache::verify_clean_inline_caches(); 4716 4717 CodeCache::set_needs_cache_clean(false); 4718 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 4719 4720 CodeCache::verify_icholder_relocations(); 4721 } 4722 4723 private: 4724 void add_to_postponed_list(nmethod* nm) { 4725 nmethod* old; 4726 do { 4727 old = (nmethod*)_postponed_list; 4728 nm->set_unloading_next(old); 4729 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 4730 } 4731 4732 void clean_nmethod(nmethod* nm) { 4733 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 4734 4735 if (postponed) { 4736 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 4737 add_to_postponed_list(nm); 4738 } 4739 4740 // Mark that this thread has been cleaned/unloaded. 4741 // After this call, it will be safe to ask if this nmethod was unloaded or not. 4742 nm->set_unloading_clock(nmethod::global_unloading_clock()); 4743 } 4744 4745 void clean_nmethod_postponed(nmethod* nm) { 4746 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 4747 } 4748 4749 static const int MaxClaimNmethods = 16; 4750 4751 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 4752 nmethod* first; 4753 NMethodIterator last; 4754 4755 do { 4756 *num_claimed_nmethods = 0; 4757 4758 first = (nmethod*)_claimed_nmethod; 4759 last = NMethodIterator(first); 4760 4761 if (first != NULL) { 4762 4763 for (int i = 0; i < MaxClaimNmethods; i++) { 4764 if (!last.next_alive()) { 4765 break; 4766 } 4767 claimed_nmethods[i] = last.method(); 4768 (*num_claimed_nmethods)++; 4769 } 4770 } 4771 4772 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 4773 } 4774 4775 nmethod* claim_postponed_nmethod() { 4776 nmethod* claim; 4777 nmethod* next; 4778 4779 do { 4780 claim = (nmethod*)_postponed_list; 4781 if (claim == NULL) { 4782 return NULL; 4783 } 4784 4785 next = claim->unloading_next(); 4786 4787 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 4788 4789 return claim; 4790 } 4791 4792 public: 4793 // Mark that we're done with the first pass of nmethod cleaning. 4794 void barrier_mark(uint worker_id) { 4795 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4796 _num_entered_barrier++; 4797 if (_num_entered_barrier == _num_workers) { 4798 ml.notify_all(); 4799 } 4800 } 4801 4802 // See if we have to wait for the other workers to 4803 // finish their first-pass nmethod cleaning work. 4804 void barrier_wait(uint worker_id) { 4805 if (_num_entered_barrier < _num_workers) { 4806 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4807 while (_num_entered_barrier < _num_workers) { 4808 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 4809 } 4810 } 4811 } 4812 4813 // Cleaning and unloading of nmethods. Some work has to be postponed 4814 // to the second pass, when we know which nmethods survive. 4815 void work_first_pass(uint worker_id) { 4816 // The first nmethods is claimed by the first worker. 4817 if (worker_id == 0 && _first_nmethod != NULL) { 4818 clean_nmethod(_first_nmethod); 4819 _first_nmethod = NULL; 4820 } 4821 4822 int num_claimed_nmethods; 4823 nmethod* claimed_nmethods[MaxClaimNmethods]; 4824 4825 while (true) { 4826 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 4827 4828 if (num_claimed_nmethods == 0) { 4829 break; 4830 } 4831 4832 for (int i = 0; i < num_claimed_nmethods; i++) { 4833 clean_nmethod(claimed_nmethods[i]); 4834 } 4835 } 4836 } 4837 4838 void work_second_pass(uint worker_id) { 4839 nmethod* nm; 4840 // Take care of postponed nmethods. 4841 while ((nm = claim_postponed_nmethod()) != NULL) { 4842 clean_nmethod_postponed(nm); 4843 } 4844 } 4845 }; 4846 4847 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 4848 4849 class G1KlassCleaningTask : public StackObj { 4850 BoolObjectClosure* _is_alive; 4851 volatile jint _clean_klass_tree_claimed; 4852 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 4853 4854 public: 4855 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 4856 _is_alive(is_alive), 4857 _clean_klass_tree_claimed(0), 4858 _klass_iterator() { 4859 } 4860 4861 private: 4862 bool claim_clean_klass_tree_task() { 4863 if (_clean_klass_tree_claimed) { 4864 return false; 4865 } 4866 4867 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 4868 } 4869 4870 InstanceKlass* claim_next_klass() { 4871 Klass* klass; 4872 do { 4873 klass =_klass_iterator.next_klass(); 4874 } while (klass != NULL && !klass->oop_is_instance()); 4875 4876 return (InstanceKlass*)klass; 4877 } 4878 4879 public: 4880 4881 void clean_klass(InstanceKlass* ik) { 4882 ik->clean_implementors_list(_is_alive); 4883 ik->clean_method_data(_is_alive); 4884 4885 // G1 specific cleanup work that has 4886 // been moved here to be done in parallel. 4887 ik->clean_dependent_nmethods(); 4888 } 4889 4890 void work() { 4891 ResourceMark rm; 4892 4893 // One worker will clean the subklass/sibling klass tree. 4894 if (claim_clean_klass_tree_task()) { 4895 Klass::clean_subklass_tree(_is_alive); 4896 } 4897 4898 // All workers will help cleaning the classes, 4899 InstanceKlass* klass; 4900 while ((klass = claim_next_klass()) != NULL) { 4901 clean_klass(klass); 4902 } 4903 } 4904 }; 4905 4906 // To minimize the remark pause times, the tasks below are done in parallel. 4907 class G1ParallelCleaningTask : public AbstractGangTask { 4908 private: 4909 G1StringSymbolTableUnlinkTask _string_symbol_task; 4910 G1CodeCacheUnloadingTask _code_cache_task; 4911 G1KlassCleaningTask _klass_cleaning_task; 4912 4913 public: 4914 // The constructor is run in the VMThread. 4915 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 4916 AbstractGangTask("Parallel Cleaning"), 4917 _string_symbol_task(is_alive, process_strings, process_symbols), 4918 _code_cache_task(num_workers, is_alive, unloading_occurred), 4919 _klass_cleaning_task(is_alive) { 4920 } 4921 4922 // The parallel work done by all worker threads. 4923 void work(uint worker_id) { 4924 // Do first pass of code cache cleaning. 4925 _code_cache_task.work_first_pass(worker_id); 4926 4927 // Let the threads mark that the first pass is done. 4928 _code_cache_task.barrier_mark(worker_id); 4929 4930 // Clean the Strings and Symbols. 4931 _string_symbol_task.work(worker_id); 4932 4933 // Wait for all workers to finish the first code cache cleaning pass. 4934 _code_cache_task.barrier_wait(worker_id); 4935 4936 // Do the second code cache cleaning work, which realize on 4937 // the liveness information gathered during the first pass. 4938 _code_cache_task.work_second_pass(worker_id); 4939 4940 // Clean all klasses that were not unloaded. 4941 _klass_cleaning_task.work(); 4942 } 4943 }; 4944 4945 4946 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 4947 bool process_strings, 4948 bool process_symbols, 4949 bool class_unloading_occurred) { 4950 uint n_workers = workers()->active_workers(); 4951 4952 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 4953 n_workers, class_unloading_occurred); 4954 workers()->run_task(&g1_unlink_task); 4955 } 4956 4957 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 4958 bool process_strings, bool process_symbols) { 4959 { 4960 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 4961 workers()->run_task(&g1_unlink_task); 4962 } 4963 4964 if (G1StringDedup::is_enabled()) { 4965 G1StringDedup::unlink(is_alive); 4966 } 4967 } 4968 4969 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 4970 private: 4971 DirtyCardQueueSet* _queue; 4972 public: 4973 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 4974 4975 virtual void work(uint worker_id) { 4976 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4977 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 4978 4979 RedirtyLoggedCardTableEntryClosure cl; 4980 _queue->par_apply_closure_to_all_completed_buffers(&cl); 4981 4982 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed()); 4983 } 4984 }; 4985 4986 void G1CollectedHeap::redirty_logged_cards() { 4987 double redirty_logged_cards_start = os::elapsedTime(); 4988 4989 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 4990 dirty_card_queue_set().reset_for_par_iteration(); 4991 workers()->run_task(&redirty_task); 4992 4993 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 4994 dcq.merge_bufferlists(&dirty_card_queue_set()); 4995 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 4996 4997 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 4998 } 4999 5000 // Weak Reference Processing support 5001 5002 // An always "is_alive" closure that is used to preserve referents. 5003 // If the object is non-null then it's alive. Used in the preservation 5004 // of referent objects that are pointed to by reference objects 5005 // discovered by the CM ref processor. 5006 class G1AlwaysAliveClosure: public BoolObjectClosure { 5007 G1CollectedHeap* _g1; 5008 public: 5009 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5010 bool do_object_b(oop p) { 5011 if (p != NULL) { 5012 return true; 5013 } 5014 return false; 5015 } 5016 }; 5017 5018 bool G1STWIsAliveClosure::do_object_b(oop p) { 5019 // An object is reachable if it is outside the collection set, 5020 // or is inside and copied. 5021 return !_g1->is_in_cset(p) || p->is_forwarded(); 5022 } 5023 5024 // Non Copying Keep Alive closure 5025 class G1KeepAliveClosure: public OopClosure { 5026 G1CollectedHeap* _g1; 5027 public: 5028 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5029 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 5030 void do_oop(oop* p) { 5031 oop obj = *p; 5032 assert(obj != NULL, "the caller should have filtered out NULL values"); 5033 5034 const InCSetState cset_state = _g1->in_cset_state(obj); 5035 if (!cset_state.is_in_cset_or_humongous()) { 5036 return; 5037 } 5038 if (cset_state.is_in_cset()) { 5039 assert( obj->is_forwarded(), "invariant" ); 5040 *p = obj->forwardee(); 5041 } else { 5042 assert(!obj->is_forwarded(), "invariant" ); 5043 assert(cset_state.is_humongous(), 5044 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value())); 5045 _g1->set_humongous_is_live(obj); 5046 } 5047 } 5048 }; 5049 5050 // Copying Keep Alive closure - can be called from both 5051 // serial and parallel code as long as different worker 5052 // threads utilize different G1ParScanThreadState instances 5053 // and different queues. 5054 5055 class G1CopyingKeepAliveClosure: public OopClosure { 5056 G1CollectedHeap* _g1h; 5057 OopClosure* _copy_non_heap_obj_cl; 5058 G1ParScanThreadState* _par_scan_state; 5059 5060 public: 5061 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 5062 OopClosure* non_heap_obj_cl, 5063 G1ParScanThreadState* pss): 5064 _g1h(g1h), 5065 _copy_non_heap_obj_cl(non_heap_obj_cl), 5066 _par_scan_state(pss) 5067 {} 5068 5069 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 5070 virtual void do_oop( oop* p) { do_oop_work(p); } 5071 5072 template <class T> void do_oop_work(T* p) { 5073 oop obj = oopDesc::load_decode_heap_oop(p); 5074 5075 if (_g1h->is_in_cset_or_humongous(obj)) { 5076 // If the referent object has been forwarded (either copied 5077 // to a new location or to itself in the event of an 5078 // evacuation failure) then we need to update the reference 5079 // field and, if both reference and referent are in the G1 5080 // heap, update the RSet for the referent. 5081 // 5082 // If the referent has not been forwarded then we have to keep 5083 // it alive by policy. Therefore we have copy the referent. 5084 // 5085 // If the reference field is in the G1 heap then we can push 5086 // on the PSS queue. When the queue is drained (after each 5087 // phase of reference processing) the object and it's followers 5088 // will be copied, the reference field set to point to the 5089 // new location, and the RSet updated. Otherwise we need to 5090 // use the the non-heap or metadata closures directly to copy 5091 // the referent object and update the pointer, while avoiding 5092 // updating the RSet. 5093 5094 if (_g1h->is_in_g1_reserved(p)) { 5095 _par_scan_state->push_on_queue(p); 5096 } else { 5097 assert(!Metaspace::contains((const void*)p), 5098 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p))); 5099 _copy_non_heap_obj_cl->do_oop(p); 5100 } 5101 } 5102 } 5103 }; 5104 5105 // Serial drain queue closure. Called as the 'complete_gc' 5106 // closure for each discovered list in some of the 5107 // reference processing phases. 5108 5109 class G1STWDrainQueueClosure: public VoidClosure { 5110 protected: 5111 G1CollectedHeap* _g1h; 5112 G1ParScanThreadState* _par_scan_state; 5113 5114 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5115 5116 public: 5117 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5118 _g1h(g1h), 5119 _par_scan_state(pss) 5120 { } 5121 5122 void do_void() { 5123 G1ParScanThreadState* const pss = par_scan_state(); 5124 pss->trim_queue(); 5125 } 5126 }; 5127 5128 // Parallel Reference Processing closures 5129 5130 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5131 // processing during G1 evacuation pauses. 5132 5133 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5134 private: 5135 G1CollectedHeap* _g1h; 5136 RefToScanQueueSet* _queues; 5137 FlexibleWorkGang* _workers; 5138 uint _active_workers; 5139 5140 public: 5141 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5142 FlexibleWorkGang* workers, 5143 RefToScanQueueSet *task_queues, 5144 uint n_workers) : 5145 _g1h(g1h), 5146 _queues(task_queues), 5147 _workers(workers), 5148 _active_workers(n_workers) 5149 { 5150 assert(n_workers > 0, "shouldn't call this otherwise"); 5151 } 5152 5153 // Executes the given task using concurrent marking worker threads. 5154 virtual void execute(ProcessTask& task); 5155 virtual void execute(EnqueueTask& task); 5156 }; 5157 5158 // Gang task for possibly parallel reference processing 5159 5160 class G1STWRefProcTaskProxy: public AbstractGangTask { 5161 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5162 ProcessTask& _proc_task; 5163 G1CollectedHeap* _g1h; 5164 RefToScanQueueSet *_task_queues; 5165 ParallelTaskTerminator* _terminator; 5166 5167 public: 5168 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5169 G1CollectedHeap* g1h, 5170 RefToScanQueueSet *task_queues, 5171 ParallelTaskTerminator* terminator) : 5172 AbstractGangTask("Process reference objects in parallel"), 5173 _proc_task(proc_task), 5174 _g1h(g1h), 5175 _task_queues(task_queues), 5176 _terminator(terminator) 5177 {} 5178 5179 virtual void work(uint worker_id) { 5180 // The reference processing task executed by a single worker. 5181 ResourceMark rm; 5182 HandleMark hm; 5183 5184 G1STWIsAliveClosure is_alive(_g1h); 5185 5186 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5187 5188 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5189 5190 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5191 5192 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5193 5194 if (_g1h->collector_state()->during_initial_mark_pause()) { 5195 // We also need to mark copied objects. 5196 copy_non_heap_cl = ©_mark_non_heap_cl; 5197 } 5198 5199 // Keep alive closure. 5200 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5201 5202 // Complete GC closure 5203 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5204 5205 // Call the reference processing task's work routine. 5206 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5207 5208 // Note we cannot assert that the refs array is empty here as not all 5209 // of the processing tasks (specifically phase2 - pp2_work) execute 5210 // the complete_gc closure (which ordinarily would drain the queue) so 5211 // the queue may not be empty. 5212 } 5213 }; 5214 5215 // Driver routine for parallel reference processing. 5216 // Creates an instance of the ref processing gang 5217 // task and has the worker threads execute it. 5218 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5219 assert(_workers != NULL, "Need parallel worker threads."); 5220 5221 ParallelTaskTerminator terminator(_active_workers, _queues); 5222 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5223 5224 _workers->run_task(&proc_task_proxy); 5225 } 5226 5227 // Gang task for parallel reference enqueueing. 5228 5229 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5230 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5231 EnqueueTask& _enq_task; 5232 5233 public: 5234 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5235 AbstractGangTask("Enqueue reference objects in parallel"), 5236 _enq_task(enq_task) 5237 { } 5238 5239 virtual void work(uint worker_id) { 5240 _enq_task.work(worker_id); 5241 } 5242 }; 5243 5244 // Driver routine for parallel reference enqueueing. 5245 // Creates an instance of the ref enqueueing gang 5246 // task and has the worker threads execute it. 5247 5248 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5249 assert(_workers != NULL, "Need parallel worker threads."); 5250 5251 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5252 5253 _workers->run_task(&enq_task_proxy); 5254 } 5255 5256 // End of weak reference support closures 5257 5258 // Abstract task used to preserve (i.e. copy) any referent objects 5259 // that are in the collection set and are pointed to by reference 5260 // objects discovered by the CM ref processor. 5261 5262 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5263 protected: 5264 G1CollectedHeap* _g1h; 5265 RefToScanQueueSet *_queues; 5266 ParallelTaskTerminator _terminator; 5267 uint _n_workers; 5268 5269 public: 5270 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, uint workers, RefToScanQueueSet *task_queues) : 5271 AbstractGangTask("ParPreserveCMReferents"), 5272 _g1h(g1h), 5273 _queues(task_queues), 5274 _terminator(workers, _queues), 5275 _n_workers(workers) 5276 { } 5277 5278 void work(uint worker_id) { 5279 ResourceMark rm; 5280 HandleMark hm; 5281 5282 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5283 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5284 5285 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5286 5287 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5288 5289 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5290 5291 if (_g1h->collector_state()->during_initial_mark_pause()) { 5292 // We also need to mark copied objects. 5293 copy_non_heap_cl = ©_mark_non_heap_cl; 5294 } 5295 5296 // Is alive closure 5297 G1AlwaysAliveClosure always_alive(_g1h); 5298 5299 // Copying keep alive closure. Applied to referent objects that need 5300 // to be copied. 5301 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5302 5303 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5304 5305 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5306 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5307 5308 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5309 // So this must be true - but assert just in case someone decides to 5310 // change the worker ids. 5311 assert(worker_id < limit, "sanity"); 5312 assert(!rp->discovery_is_atomic(), "check this code"); 5313 5314 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5315 for (uint idx = worker_id; idx < limit; idx += stride) { 5316 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5317 5318 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5319 while (iter.has_next()) { 5320 // Since discovery is not atomic for the CM ref processor, we 5321 // can see some null referent objects. 5322 iter.load_ptrs(DEBUG_ONLY(true)); 5323 oop ref = iter.obj(); 5324 5325 // This will filter nulls. 5326 if (iter.is_referent_alive()) { 5327 iter.make_referent_alive(); 5328 } 5329 iter.move_to_next(); 5330 } 5331 } 5332 5333 // Drain the queue - which may cause stealing 5334 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5335 drain_queue.do_void(); 5336 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5337 assert(pss.queue_is_empty(), "should be"); 5338 } 5339 }; 5340 5341 // Weak Reference processing during an evacuation pause (part 1). 5342 void G1CollectedHeap::process_discovered_references() { 5343 double ref_proc_start = os::elapsedTime(); 5344 5345 ReferenceProcessor* rp = _ref_processor_stw; 5346 assert(rp->discovery_enabled(), "should have been enabled"); 5347 5348 // Any reference objects, in the collection set, that were 'discovered' 5349 // by the CM ref processor should have already been copied (either by 5350 // applying the external root copy closure to the discovered lists, or 5351 // by following an RSet entry). 5352 // 5353 // But some of the referents, that are in the collection set, that these 5354 // reference objects point to may not have been copied: the STW ref 5355 // processor would have seen that the reference object had already 5356 // been 'discovered' and would have skipped discovering the reference, 5357 // but would not have treated the reference object as a regular oop. 5358 // As a result the copy closure would not have been applied to the 5359 // referent object. 5360 // 5361 // We need to explicitly copy these referent objects - the references 5362 // will be processed at the end of remarking. 5363 // 5364 // We also need to do this copying before we process the reference 5365 // objects discovered by the STW ref processor in case one of these 5366 // referents points to another object which is also referenced by an 5367 // object discovered by the STW ref processor. 5368 5369 uint no_of_gc_workers = workers()->active_workers(); 5370 5371 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5372 no_of_gc_workers, 5373 _task_queues); 5374 5375 workers()->run_task(&keep_cm_referents); 5376 5377 // Closure to test whether a referent is alive. 5378 G1STWIsAliveClosure is_alive(this); 5379 5380 // Even when parallel reference processing is enabled, the processing 5381 // of JNI refs is serial and performed serially by the current thread 5382 // rather than by a worker. The following PSS will be used for processing 5383 // JNI refs. 5384 5385 // Use only a single queue for this PSS. 5386 G1ParScanThreadState pss(this, 0, NULL); 5387 assert(pss.queue_is_empty(), "pre-condition"); 5388 5389 // We do not embed a reference processor in the copying/scanning 5390 // closures while we're actually processing the discovered 5391 // reference objects. 5392 5393 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5394 5395 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5396 5397 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5398 5399 if (collector_state()->during_initial_mark_pause()) { 5400 // We also need to mark copied objects. 5401 copy_non_heap_cl = ©_mark_non_heap_cl; 5402 } 5403 5404 // Keep alive closure. 5405 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss); 5406 5407 // Serial Complete GC closure 5408 G1STWDrainQueueClosure drain_queue(this, &pss); 5409 5410 // Setup the soft refs policy... 5411 rp->setup_policy(false); 5412 5413 ReferenceProcessorStats stats; 5414 if (!rp->processing_is_mt()) { 5415 // Serial reference processing... 5416 stats = rp->process_discovered_references(&is_alive, 5417 &keep_alive, 5418 &drain_queue, 5419 NULL, 5420 _gc_timer_stw, 5421 _gc_tracer_stw->gc_id()); 5422 } else { 5423 // Parallel reference processing 5424 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5425 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5426 5427 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5428 stats = rp->process_discovered_references(&is_alive, 5429 &keep_alive, 5430 &drain_queue, 5431 &par_task_executor, 5432 _gc_timer_stw, 5433 _gc_tracer_stw->gc_id()); 5434 } 5435 5436 _gc_tracer_stw->report_gc_reference_stats(stats); 5437 5438 // We have completed copying any necessary live referent objects. 5439 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5440 5441 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5442 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5443 } 5444 5445 // Weak Reference processing during an evacuation pause (part 2). 5446 void G1CollectedHeap::enqueue_discovered_references() { 5447 double ref_enq_start = os::elapsedTime(); 5448 5449 ReferenceProcessor* rp = _ref_processor_stw; 5450 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5451 5452 // Now enqueue any remaining on the discovered lists on to 5453 // the pending list. 5454 if (!rp->processing_is_mt()) { 5455 // Serial reference processing... 5456 rp->enqueue_discovered_references(); 5457 } else { 5458 // Parallel reference enqueueing 5459 5460 uint n_workers = workers()->active_workers(); 5461 5462 assert(rp->num_q() == n_workers, "sanity"); 5463 assert(n_workers <= rp->max_num_q(), "sanity"); 5464 5465 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, n_workers); 5466 rp->enqueue_discovered_references(&par_task_executor); 5467 } 5468 5469 rp->verify_no_references_recorded(); 5470 assert(!rp->discovery_enabled(), "should have been disabled"); 5471 5472 // FIXME 5473 // CM's reference processing also cleans up the string and symbol tables. 5474 // Should we do that here also? We could, but it is a serial operation 5475 // and could significantly increase the pause time. 5476 5477 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5478 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5479 } 5480 5481 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5482 _expand_heap_after_alloc_failure = true; 5483 _evacuation_failed = false; 5484 5485 // Should G1EvacuationFailureALot be in effect for this GC? 5486 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5487 5488 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5489 5490 // Disable the hot card cache. 5491 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5492 hot_card_cache->reset_hot_cache_claimed_index(); 5493 hot_card_cache->set_use_cache(false); 5494 5495 const uint n_workers = workers()->active_workers(); 5496 5497 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5498 double start_par_time_sec = os::elapsedTime(); 5499 double end_par_time_sec; 5500 5501 { 5502 G1RootProcessor root_processor(this, n_workers); 5503 G1ParTask g1_par_task(this, _task_queues, &root_processor, n_workers); 5504 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5505 if (collector_state()->during_initial_mark_pause()) { 5506 ClassLoaderDataGraph::clear_claimed_marks(); 5507 } 5508 5509 // The individual threads will set their evac-failure closures. 5510 if (PrintTerminationStats) { 5511 G1ParScanThreadState::print_termination_stats_hdr(); 5512 } 5513 5514 workers()->run_task(&g1_par_task); 5515 end_par_time_sec = os::elapsedTime(); 5516 5517 // Closing the inner scope will execute the destructor 5518 // for the G1RootProcessor object. We record the current 5519 // elapsed time before closing the scope so that time 5520 // taken for the destructor is NOT included in the 5521 // reported parallel time. 5522 } 5523 5524 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 5525 5526 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5527 phase_times->record_par_time(par_time_ms); 5528 5529 double code_root_fixup_time_ms = 5530 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5531 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 5532 5533 // Process any discovered reference objects - we have 5534 // to do this _before_ we retire the GC alloc regions 5535 // as we may have to copy some 'reachable' referent 5536 // objects (and their reachable sub-graphs) that were 5537 // not copied during the pause. 5538 process_discovered_references(); 5539 5540 if (G1StringDedup::is_enabled()) { 5541 double fixup_start = os::elapsedTime(); 5542 5543 G1STWIsAliveClosure is_alive(this); 5544 G1KeepAliveClosure keep_alive(this); 5545 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times); 5546 5547 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 5548 phase_times->record_string_dedup_fixup_time(fixup_time_ms); 5549 } 5550 5551 _allocator->release_gc_alloc_regions(evacuation_info); 5552 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5553 5554 record_obj_copy_mem_stats(); 5555 5556 // Reset and re-enable the hot card cache. 5557 // Note the counts for the cards in the regions in the 5558 // collection set are reset when the collection set is freed. 5559 hot_card_cache->reset_hot_cache(); 5560 hot_card_cache->set_use_cache(true); 5561 5562 purge_code_root_memory(); 5563 5564 if (evacuation_failed()) { 5565 remove_self_forwarding_pointers(); 5566 5567 // Reset the G1EvacuationFailureALot counters and flags 5568 // Note: the values are reset only when an actual 5569 // evacuation failure occurs. 5570 NOT_PRODUCT(reset_evacuation_should_fail();) 5571 } 5572 5573 // Enqueue any remaining references remaining on the STW 5574 // reference processor's discovered lists. We need to do 5575 // this after the card table is cleaned (and verified) as 5576 // the act of enqueueing entries on to the pending list 5577 // will log these updates (and dirty their associated 5578 // cards). We need these updates logged to update any 5579 // RSets. 5580 enqueue_discovered_references(); 5581 5582 redirty_logged_cards(); 5583 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5584 } 5585 5586 void G1CollectedHeap::record_obj_copy_mem_stats() { 5587 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 5588 create_g1_evac_summary(&_old_evac_stats)); 5589 } 5590 5591 void G1CollectedHeap::free_region(HeapRegion* hr, 5592 FreeRegionList* free_list, 5593 bool par, 5594 bool locked) { 5595 assert(!hr->is_free(), "the region should not be free"); 5596 assert(!hr->is_empty(), "the region should not be empty"); 5597 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 5598 assert(free_list != NULL, "pre-condition"); 5599 5600 if (G1VerifyBitmaps) { 5601 MemRegion mr(hr->bottom(), hr->end()); 5602 concurrent_mark()->clearRangePrevBitmap(mr); 5603 } 5604 5605 // Clear the card counts for this region. 5606 // Note: we only need to do this if the region is not young 5607 // (since we don't refine cards in young regions). 5608 if (!hr->is_young()) { 5609 _cg1r->hot_card_cache()->reset_card_counts(hr); 5610 } 5611 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5612 free_list->add_ordered(hr); 5613 } 5614 5615 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5616 FreeRegionList* free_list, 5617 bool par) { 5618 assert(hr->is_starts_humongous(), "this is only for starts humongous regions"); 5619 assert(free_list != NULL, "pre-condition"); 5620 5621 size_t hr_capacity = hr->capacity(); 5622 // We need to read this before we make the region non-humongous, 5623 // otherwise the information will be gone. 5624 uint last_index = hr->last_hc_index(); 5625 hr->clear_humongous(); 5626 free_region(hr, free_list, par); 5627 5628 uint i = hr->hrm_index() + 1; 5629 while (i < last_index) { 5630 HeapRegion* curr_hr = region_at(i); 5631 assert(curr_hr->is_continues_humongous(), "invariant"); 5632 curr_hr->clear_humongous(); 5633 free_region(curr_hr, free_list, par); 5634 i += 1; 5635 } 5636 } 5637 5638 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 5639 const HeapRegionSetCount& humongous_regions_removed) { 5640 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5641 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5642 _old_set.bulk_remove(old_regions_removed); 5643 _humongous_set.bulk_remove(humongous_regions_removed); 5644 } 5645 5646 } 5647 5648 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 5649 assert(list != NULL, "list can't be null"); 5650 if (!list->is_empty()) { 5651 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5652 _hrm.insert_list_into_free_list(list); 5653 } 5654 } 5655 5656 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 5657 decrease_used(bytes); 5658 } 5659 5660 class G1ParCleanupCTTask : public AbstractGangTask { 5661 G1SATBCardTableModRefBS* _ct_bs; 5662 G1CollectedHeap* _g1h; 5663 HeapRegion* volatile _su_head; 5664 public: 5665 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 5666 G1CollectedHeap* g1h) : 5667 AbstractGangTask("G1 Par Cleanup CT Task"), 5668 _ct_bs(ct_bs), _g1h(g1h) { } 5669 5670 void work(uint worker_id) { 5671 HeapRegion* r; 5672 while (r = _g1h->pop_dirty_cards_region()) { 5673 clear_cards(r); 5674 } 5675 } 5676 5677 void clear_cards(HeapRegion* r) { 5678 // Cards of the survivors should have already been dirtied. 5679 if (!r->is_survivor()) { 5680 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5681 } 5682 } 5683 }; 5684 5685 #ifndef PRODUCT 5686 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5687 G1CollectedHeap* _g1h; 5688 G1SATBCardTableModRefBS* _ct_bs; 5689 public: 5690 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 5691 : _g1h(g1h), _ct_bs(ct_bs) { } 5692 virtual bool doHeapRegion(HeapRegion* r) { 5693 if (r->is_survivor()) { 5694 _g1h->verify_dirty_region(r); 5695 } else { 5696 _g1h->verify_not_dirty_region(r); 5697 } 5698 return false; 5699 } 5700 }; 5701 5702 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5703 // All of the region should be clean. 5704 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5705 MemRegion mr(hr->bottom(), hr->end()); 5706 ct_bs->verify_not_dirty_region(mr); 5707 } 5708 5709 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5710 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5711 // dirty allocated blocks as they allocate them. The thread that 5712 // retires each region and replaces it with a new one will do a 5713 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5714 // not dirty that area (one less thing to have to do while holding 5715 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5716 // is dirty. 5717 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5718 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5719 if (hr->is_young()) { 5720 ct_bs->verify_g1_young_region(mr); 5721 } else { 5722 ct_bs->verify_dirty_region(mr); 5723 } 5724 } 5725 5726 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5727 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5728 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5729 verify_dirty_region(hr); 5730 } 5731 } 5732 5733 void G1CollectedHeap::verify_dirty_young_regions() { 5734 verify_dirty_young_list(_young_list->first_region()); 5735 } 5736 5737 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 5738 HeapWord* tams, HeapWord* end) { 5739 guarantee(tams <= end, 5740 err_msg("tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end))); 5741 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 5742 if (result < end) { 5743 gclog_or_tty->cr(); 5744 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT, 5745 bitmap_name, p2i(result)); 5746 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT, 5747 bitmap_name, p2i(tams), p2i(end)); 5748 return false; 5749 } 5750 return true; 5751 } 5752 5753 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 5754 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 5755 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 5756 5757 HeapWord* bottom = hr->bottom(); 5758 HeapWord* ptams = hr->prev_top_at_mark_start(); 5759 HeapWord* ntams = hr->next_top_at_mark_start(); 5760 HeapWord* end = hr->end(); 5761 5762 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 5763 5764 bool res_n = true; 5765 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 5766 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 5767 // if we happen to be in that state. 5768 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) { 5769 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 5770 } 5771 if (!res_p || !res_n) { 5772 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT, 5773 HR_FORMAT_PARAMS(hr)); 5774 gclog_or_tty->print_cr("#### Caller: %s", caller); 5775 return false; 5776 } 5777 return true; 5778 } 5779 5780 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 5781 if (!G1VerifyBitmaps) return; 5782 5783 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 5784 } 5785 5786 class G1VerifyBitmapClosure : public HeapRegionClosure { 5787 private: 5788 const char* _caller; 5789 G1CollectedHeap* _g1h; 5790 bool _failures; 5791 5792 public: 5793 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 5794 _caller(caller), _g1h(g1h), _failures(false) { } 5795 5796 bool failures() { return _failures; } 5797 5798 virtual bool doHeapRegion(HeapRegion* hr) { 5799 if (hr->is_continues_humongous()) return false; 5800 5801 bool result = _g1h->verify_bitmaps(_caller, hr); 5802 if (!result) { 5803 _failures = true; 5804 } 5805 return false; 5806 } 5807 }; 5808 5809 void G1CollectedHeap::check_bitmaps(const char* caller) { 5810 if (!G1VerifyBitmaps) return; 5811 5812 G1VerifyBitmapClosure cl(caller, this); 5813 heap_region_iterate(&cl); 5814 guarantee(!cl.failures(), "bitmap verification"); 5815 } 5816 5817 class G1CheckCSetFastTableClosure : public HeapRegionClosure { 5818 private: 5819 bool _failures; 5820 public: 5821 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { } 5822 5823 virtual bool doHeapRegion(HeapRegion* hr) { 5824 uint i = hr->hrm_index(); 5825 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i); 5826 if (hr->is_humongous()) { 5827 if (hr->in_collection_set()) { 5828 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i); 5829 _failures = true; 5830 return true; 5831 } 5832 if (cset_state.is_in_cset()) { 5833 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i); 5834 _failures = true; 5835 return true; 5836 } 5837 if (hr->is_continues_humongous() && cset_state.is_humongous()) { 5838 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i); 5839 _failures = true; 5840 return true; 5841 } 5842 } else { 5843 if (cset_state.is_humongous()) { 5844 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i); 5845 _failures = true; 5846 return true; 5847 } 5848 if (hr->in_collection_set() != cset_state.is_in_cset()) { 5849 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u", 5850 hr->in_collection_set(), cset_state.value(), i); 5851 _failures = true; 5852 return true; 5853 } 5854 if (cset_state.is_in_cset()) { 5855 if (hr->is_young() != (cset_state.is_young())) { 5856 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u", 5857 hr->is_young(), cset_state.value(), i); 5858 _failures = true; 5859 return true; 5860 } 5861 if (hr->is_old() != (cset_state.is_old())) { 5862 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u", 5863 hr->is_old(), cset_state.value(), i); 5864 _failures = true; 5865 return true; 5866 } 5867 } 5868 } 5869 return false; 5870 } 5871 5872 bool failures() const { return _failures; } 5873 }; 5874 5875 bool G1CollectedHeap::check_cset_fast_test() { 5876 G1CheckCSetFastTableClosure cl; 5877 _hrm.iterate(&cl); 5878 return !cl.failures(); 5879 } 5880 #endif // PRODUCT 5881 5882 void G1CollectedHeap::cleanUpCardTable() { 5883 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5884 double start = os::elapsedTime(); 5885 5886 { 5887 // Iterate over the dirty cards region list. 5888 G1ParCleanupCTTask cleanup_task(ct_bs, this); 5889 5890 workers()->run_task(&cleanup_task); 5891 #ifndef PRODUCT 5892 if (G1VerifyCTCleanup || VerifyAfterGC) { 5893 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 5894 heap_region_iterate(&cleanup_verifier); 5895 } 5896 #endif 5897 } 5898 5899 double elapsed = os::elapsedTime() - start; 5900 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 5901 } 5902 5903 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 5904 size_t pre_used = 0; 5905 FreeRegionList local_free_list("Local List for CSet Freeing"); 5906 5907 double young_time_ms = 0.0; 5908 double non_young_time_ms = 0.0; 5909 5910 // Since the collection set is a superset of the the young list, 5911 // all we need to do to clear the young list is clear its 5912 // head and length, and unlink any young regions in the code below 5913 _young_list->clear(); 5914 5915 G1CollectorPolicy* policy = g1_policy(); 5916 5917 double start_sec = os::elapsedTime(); 5918 bool non_young = true; 5919 5920 HeapRegion* cur = cs_head; 5921 int age_bound = -1; 5922 size_t rs_lengths = 0; 5923 5924 while (cur != NULL) { 5925 assert(!is_on_master_free_list(cur), "sanity"); 5926 if (non_young) { 5927 if (cur->is_young()) { 5928 double end_sec = os::elapsedTime(); 5929 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5930 non_young_time_ms += elapsed_ms; 5931 5932 start_sec = os::elapsedTime(); 5933 non_young = false; 5934 } 5935 } else { 5936 if (!cur->is_young()) { 5937 double end_sec = os::elapsedTime(); 5938 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5939 young_time_ms += elapsed_ms; 5940 5941 start_sec = os::elapsedTime(); 5942 non_young = true; 5943 } 5944 } 5945 5946 rs_lengths += cur->rem_set()->occupied_locked(); 5947 5948 HeapRegion* next = cur->next_in_collection_set(); 5949 assert(cur->in_collection_set(), "bad CS"); 5950 cur->set_next_in_collection_set(NULL); 5951 clear_in_cset(cur); 5952 5953 if (cur->is_young()) { 5954 int index = cur->young_index_in_cset(); 5955 assert(index != -1, "invariant"); 5956 assert((uint) index < policy->young_cset_region_length(), "invariant"); 5957 size_t words_survived = _surviving_young_words[index]; 5958 cur->record_surv_words_in_group(words_survived); 5959 5960 // At this point the we have 'popped' cur from the collection set 5961 // (linked via next_in_collection_set()) but it is still in the 5962 // young list (linked via next_young_region()). Clear the 5963 // _next_young_region field. 5964 cur->set_next_young_region(NULL); 5965 } else { 5966 int index = cur->young_index_in_cset(); 5967 assert(index == -1, "invariant"); 5968 } 5969 5970 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 5971 (!cur->is_young() && cur->young_index_in_cset() == -1), 5972 "invariant" ); 5973 5974 if (!cur->evacuation_failed()) { 5975 MemRegion used_mr = cur->used_region(); 5976 5977 // And the region is empty. 5978 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 5979 pre_used += cur->used(); 5980 free_region(cur, &local_free_list, false /* par */, true /* locked */); 5981 } else { 5982 cur->uninstall_surv_rate_group(); 5983 if (cur->is_young()) { 5984 cur->set_young_index_in_cset(-1); 5985 } 5986 cur->set_evacuation_failed(false); 5987 // The region is now considered to be old. 5988 cur->set_old(); 5989 // Do some allocation statistics accounting. Regions that failed evacuation 5990 // are always made old, so there is no need to update anything in the young 5991 // gen statistics, but we need to update old gen statistics. 5992 size_t used_words = cur->marked_bytes() / HeapWordSize; 5993 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words); 5994 _old_set.add(cur); 5995 evacuation_info.increment_collectionset_used_after(cur->used()); 5996 } 5997 cur = next; 5998 } 5999 6000 evacuation_info.set_regions_freed(local_free_list.length()); 6001 policy->record_max_rs_lengths(rs_lengths); 6002 policy->cset_regions_freed(); 6003 6004 double end_sec = os::elapsedTime(); 6005 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6006 6007 if (non_young) { 6008 non_young_time_ms += elapsed_ms; 6009 } else { 6010 young_time_ms += elapsed_ms; 6011 } 6012 6013 prepend_to_freelist(&local_free_list); 6014 decrement_summary_bytes(pre_used); 6015 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 6016 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 6017 } 6018 6019 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 6020 private: 6021 FreeRegionList* _free_region_list; 6022 HeapRegionSet* _proxy_set; 6023 HeapRegionSetCount _humongous_regions_removed; 6024 size_t _freed_bytes; 6025 public: 6026 6027 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 6028 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 6029 } 6030 6031 virtual bool doHeapRegion(HeapRegion* r) { 6032 if (!r->is_starts_humongous()) { 6033 return false; 6034 } 6035 6036 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 6037 6038 oop obj = (oop)r->bottom(); 6039 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 6040 6041 // The following checks whether the humongous object is live are sufficient. 6042 // The main additional check (in addition to having a reference from the roots 6043 // or the young gen) is whether the humongous object has a remembered set entry. 6044 // 6045 // A humongous object cannot be live if there is no remembered set for it 6046 // because: 6047 // - there can be no references from within humongous starts regions referencing 6048 // the object because we never allocate other objects into them. 6049 // (I.e. there are no intra-region references that may be missed by the 6050 // remembered set) 6051 // - as soon there is a remembered set entry to the humongous starts region 6052 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 6053 // until the end of a concurrent mark. 6054 // 6055 // It is not required to check whether the object has been found dead by marking 6056 // or not, in fact it would prevent reclamation within a concurrent cycle, as 6057 // all objects allocated during that time are considered live. 6058 // SATB marking is even more conservative than the remembered set. 6059 // So if at this point in the collection there is no remembered set entry, 6060 // nobody has a reference to it. 6061 // At the start of collection we flush all refinement logs, and remembered sets 6062 // are completely up-to-date wrt to references to the humongous object. 6063 // 6064 // Other implementation considerations: 6065 // - never consider object arrays at this time because they would pose 6066 // considerable effort for cleaning up the the remembered sets. This is 6067 // required because stale remembered sets might reference locations that 6068 // are currently allocated into. 6069 uint region_idx = r->hrm_index(); 6070 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 6071 !r->rem_set()->is_empty()) { 6072 6073 if (G1TraceEagerReclaimHumongousObjects) { 6074 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", 6075 region_idx, 6076 (size_t)obj->size() * HeapWordSize, 6077 p2i(r->bottom()), 6078 r->region_num(), 6079 r->rem_set()->occupied(), 6080 r->rem_set()->strong_code_roots_list_length(), 6081 next_bitmap->isMarked(r->bottom()), 6082 g1h->is_humongous_reclaim_candidate(region_idx), 6083 obj->is_typeArray() 6084 ); 6085 } 6086 6087 return false; 6088 } 6089 6090 guarantee(obj->is_typeArray(), 6091 err_msg("Only eagerly reclaiming type arrays is supported, but the object " 6092 PTR_FORMAT " is not.", 6093 p2i(r->bottom()))); 6094 6095 if (G1TraceEagerReclaimHumongousObjects) { 6096 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", 6097 region_idx, 6098 (size_t)obj->size() * HeapWordSize, 6099 p2i(r->bottom()), 6100 r->region_num(), 6101 r->rem_set()->occupied(), 6102 r->rem_set()->strong_code_roots_list_length(), 6103 next_bitmap->isMarked(r->bottom()), 6104 g1h->is_humongous_reclaim_candidate(region_idx), 6105 obj->is_typeArray() 6106 ); 6107 } 6108 // Need to clear mark bit of the humongous object if already set. 6109 if (next_bitmap->isMarked(r->bottom())) { 6110 next_bitmap->clear(r->bottom()); 6111 } 6112 _freed_bytes += r->used(); 6113 r->set_containing_set(NULL); 6114 _humongous_regions_removed.increment(1u, r->capacity()); 6115 g1h->free_humongous_region(r, _free_region_list, false); 6116 6117 return false; 6118 } 6119 6120 HeapRegionSetCount& humongous_free_count() { 6121 return _humongous_regions_removed; 6122 } 6123 6124 size_t bytes_freed() const { 6125 return _freed_bytes; 6126 } 6127 6128 size_t humongous_reclaimed() const { 6129 return _humongous_regions_removed.length(); 6130 } 6131 }; 6132 6133 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 6134 assert_at_safepoint(true); 6135 6136 if (!G1EagerReclaimHumongousObjects || 6137 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) { 6138 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 6139 return; 6140 } 6141 6142 double start_time = os::elapsedTime(); 6143 6144 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 6145 6146 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 6147 heap_region_iterate(&cl); 6148 6149 HeapRegionSetCount empty_set; 6150 remove_from_old_sets(empty_set, cl.humongous_free_count()); 6151 6152 G1HRPrinter* hrp = hr_printer(); 6153 if (hrp->is_active()) { 6154 FreeRegionListIterator iter(&local_cleanup_list); 6155 while (iter.more_available()) { 6156 HeapRegion* hr = iter.get_next(); 6157 hrp->cleanup(hr); 6158 } 6159 } 6160 6161 prepend_to_freelist(&local_cleanup_list); 6162 decrement_summary_bytes(cl.bytes_freed()); 6163 6164 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 6165 cl.humongous_reclaimed()); 6166 } 6167 6168 // This routine is similar to the above but does not record 6169 // any policy statistics or update free lists; we are abandoning 6170 // the current incremental collection set in preparation of a 6171 // full collection. After the full GC we will start to build up 6172 // the incremental collection set again. 6173 // This is only called when we're doing a full collection 6174 // and is immediately followed by the tearing down of the young list. 6175 6176 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6177 HeapRegion* cur = cs_head; 6178 6179 while (cur != NULL) { 6180 HeapRegion* next = cur->next_in_collection_set(); 6181 assert(cur->in_collection_set(), "bad CS"); 6182 cur->set_next_in_collection_set(NULL); 6183 clear_in_cset(cur); 6184 cur->set_young_index_in_cset(-1); 6185 cur = next; 6186 } 6187 } 6188 6189 void G1CollectedHeap::set_free_regions_coming() { 6190 if (G1ConcRegionFreeingVerbose) { 6191 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6192 "setting free regions coming"); 6193 } 6194 6195 assert(!free_regions_coming(), "pre-condition"); 6196 _free_regions_coming = true; 6197 } 6198 6199 void G1CollectedHeap::reset_free_regions_coming() { 6200 assert(free_regions_coming(), "pre-condition"); 6201 6202 { 6203 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6204 _free_regions_coming = false; 6205 SecondaryFreeList_lock->notify_all(); 6206 } 6207 6208 if (G1ConcRegionFreeingVerbose) { 6209 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6210 "reset free regions coming"); 6211 } 6212 } 6213 6214 void G1CollectedHeap::wait_while_free_regions_coming() { 6215 // Most of the time we won't have to wait, so let's do a quick test 6216 // first before we take the lock. 6217 if (!free_regions_coming()) { 6218 return; 6219 } 6220 6221 if (G1ConcRegionFreeingVerbose) { 6222 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6223 "waiting for free regions"); 6224 } 6225 6226 { 6227 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6228 while (free_regions_coming()) { 6229 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6230 } 6231 } 6232 6233 if (G1ConcRegionFreeingVerbose) { 6234 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6235 "done waiting for free regions"); 6236 } 6237 } 6238 6239 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 6240 return _allocator->is_retained_old_region(hr); 6241 } 6242 6243 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6244 _young_list->push_region(hr); 6245 } 6246 6247 class NoYoungRegionsClosure: public HeapRegionClosure { 6248 private: 6249 bool _success; 6250 public: 6251 NoYoungRegionsClosure() : _success(true) { } 6252 bool doHeapRegion(HeapRegion* r) { 6253 if (r->is_young()) { 6254 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 6255 p2i(r->bottom()), p2i(r->end())); 6256 _success = false; 6257 } 6258 return false; 6259 } 6260 bool success() { return _success; } 6261 }; 6262 6263 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6264 bool ret = _young_list->check_list_empty(check_sample); 6265 6266 if (check_heap) { 6267 NoYoungRegionsClosure closure; 6268 heap_region_iterate(&closure); 6269 ret = ret && closure.success(); 6270 } 6271 6272 return ret; 6273 } 6274 6275 class TearDownRegionSetsClosure : public HeapRegionClosure { 6276 private: 6277 HeapRegionSet *_old_set; 6278 6279 public: 6280 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6281 6282 bool doHeapRegion(HeapRegion* r) { 6283 if (r->is_old()) { 6284 _old_set->remove(r); 6285 } else { 6286 // We ignore free regions, we'll empty the free list afterwards. 6287 // We ignore young regions, we'll empty the young list afterwards. 6288 // We ignore humongous regions, we're not tearing down the 6289 // humongous regions set. 6290 assert(r->is_free() || r->is_young() || r->is_humongous(), 6291 "it cannot be another type"); 6292 } 6293 return false; 6294 } 6295 6296 ~TearDownRegionSetsClosure() { 6297 assert(_old_set->is_empty(), "post-condition"); 6298 } 6299 }; 6300 6301 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6302 assert_at_safepoint(true /* should_be_vm_thread */); 6303 6304 if (!free_list_only) { 6305 TearDownRegionSetsClosure cl(&_old_set); 6306 heap_region_iterate(&cl); 6307 6308 // Note that emptying the _young_list is postponed and instead done as 6309 // the first step when rebuilding the regions sets again. The reason for 6310 // this is that during a full GC string deduplication needs to know if 6311 // a collected region was young or old when the full GC was initiated. 6312 } 6313 _hrm.remove_all_free_regions(); 6314 } 6315 6316 void G1CollectedHeap::increase_used(size_t bytes) { 6317 _summary_bytes_used += bytes; 6318 } 6319 6320 void G1CollectedHeap::decrease_used(size_t bytes) { 6321 assert(_summary_bytes_used >= bytes, 6322 err_msg("invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 6323 _summary_bytes_used, bytes)); 6324 _summary_bytes_used -= bytes; 6325 } 6326 6327 void G1CollectedHeap::set_used(size_t bytes) { 6328 _summary_bytes_used = bytes; 6329 } 6330 6331 class RebuildRegionSetsClosure : public HeapRegionClosure { 6332 private: 6333 bool _free_list_only; 6334 HeapRegionSet* _old_set; 6335 HeapRegionManager* _hrm; 6336 size_t _total_used; 6337 6338 public: 6339 RebuildRegionSetsClosure(bool free_list_only, 6340 HeapRegionSet* old_set, HeapRegionManager* hrm) : 6341 _free_list_only(free_list_only), 6342 _old_set(old_set), _hrm(hrm), _total_used(0) { 6343 assert(_hrm->num_free_regions() == 0, "pre-condition"); 6344 if (!free_list_only) { 6345 assert(_old_set->is_empty(), "pre-condition"); 6346 } 6347 } 6348 6349 bool doHeapRegion(HeapRegion* r) { 6350 if (r->is_continues_humongous()) { 6351 return false; 6352 } 6353 6354 if (r->is_empty()) { 6355 // Add free regions to the free list 6356 r->set_free(); 6357 r->set_allocation_context(AllocationContext::system()); 6358 _hrm->insert_into_free_list(r); 6359 } else if (!_free_list_only) { 6360 assert(!r->is_young(), "we should not come across young regions"); 6361 6362 if (r->is_humongous()) { 6363 // We ignore humongous regions. We left the humongous set unchanged. 6364 } else { 6365 // Objects that were compacted would have ended up on regions 6366 // that were previously old or free. Archive regions (which are 6367 // old) will not have been touched. 6368 assert(r->is_free() || r->is_old(), "invariant"); 6369 // We now consider them old, so register as such. Leave 6370 // archive regions set that way, however, while still adding 6371 // them to the old set. 6372 if (!r->is_archive()) { 6373 r->set_old(); 6374 } 6375 _old_set->add(r); 6376 } 6377 _total_used += r->used(); 6378 } 6379 6380 return false; 6381 } 6382 6383 size_t total_used() { 6384 return _total_used; 6385 } 6386 }; 6387 6388 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6389 assert_at_safepoint(true /* should_be_vm_thread */); 6390 6391 if (!free_list_only) { 6392 _young_list->empty_list(); 6393 } 6394 6395 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 6396 heap_region_iterate(&cl); 6397 6398 if (!free_list_only) { 6399 set_used(cl.total_used()); 6400 if (_archive_allocator != NULL) { 6401 _archive_allocator->clear_used(); 6402 } 6403 } 6404 assert(used_unlocked() == recalculate_used(), 6405 err_msg("inconsistent used_unlocked(), " 6406 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 6407 used_unlocked(), recalculate_used())); 6408 } 6409 6410 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6411 _refine_cte_cl->set_concurrent(concurrent); 6412 } 6413 6414 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6415 HeapRegion* hr = heap_region_containing(p); 6416 return hr->is_in(p); 6417 } 6418 6419 // Methods for the mutator alloc region 6420 6421 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6422 bool force) { 6423 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6424 assert(!force || g1_policy()->can_expand_young_list(), 6425 "if force is true we should be able to expand the young list"); 6426 bool young_list_full = g1_policy()->is_young_list_full(); 6427 if (force || !young_list_full) { 6428 HeapRegion* new_alloc_region = new_region(word_size, 6429 false /* is_old */, 6430 false /* do_expand */); 6431 if (new_alloc_region != NULL) { 6432 set_region_short_lived_locked(new_alloc_region); 6433 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6434 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6435 return new_alloc_region; 6436 } 6437 } 6438 return NULL; 6439 } 6440 6441 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6442 size_t allocated_bytes) { 6443 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6444 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 6445 6446 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6447 increase_used(allocated_bytes); 6448 _hr_printer.retire(alloc_region); 6449 // We update the eden sizes here, when the region is retired, 6450 // instead of when it's allocated, since this is the point that its 6451 // used space has been recored in _summary_bytes_used. 6452 g1mm()->update_eden_size(); 6453 } 6454 6455 // Methods for the GC alloc regions 6456 6457 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6458 uint count, 6459 InCSetState dest) { 6460 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6461 6462 if (count < g1_policy()->max_regions(dest)) { 6463 const bool is_survivor = (dest.is_young()); 6464 HeapRegion* new_alloc_region = new_region(word_size, 6465 !is_survivor, 6466 true /* do_expand */); 6467 if (new_alloc_region != NULL) { 6468 // We really only need to do this for old regions given that we 6469 // should never scan survivors. But it doesn't hurt to do it 6470 // for survivors too. 6471 new_alloc_region->record_timestamp(); 6472 if (is_survivor) { 6473 new_alloc_region->set_survivor(); 6474 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6475 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6476 } else { 6477 new_alloc_region->set_old(); 6478 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6479 check_bitmaps("Old Region Allocation", new_alloc_region); 6480 } 6481 bool during_im = collector_state()->during_initial_mark_pause(); 6482 new_alloc_region->note_start_of_copying(during_im); 6483 return new_alloc_region; 6484 } 6485 } 6486 return NULL; 6487 } 6488 6489 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6490 size_t allocated_bytes, 6491 InCSetState dest) { 6492 bool during_im = collector_state()->during_initial_mark_pause(); 6493 alloc_region->note_end_of_copying(during_im); 6494 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6495 if (dest.is_young()) { 6496 young_list()->add_survivor_region(alloc_region); 6497 } else { 6498 _old_set.add(alloc_region); 6499 } 6500 _hr_printer.retire(alloc_region); 6501 } 6502 6503 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 6504 bool expanded = false; 6505 uint index = _hrm.find_highest_free(&expanded); 6506 6507 if (index != G1_NO_HRM_INDEX) { 6508 if (expanded) { 6509 ergo_verbose1(ErgoHeapSizing, 6510 "attempt heap expansion", 6511 ergo_format_reason("requested address range outside heap bounds") 6512 ergo_format_byte("region size"), 6513 HeapRegion::GrainWords * HeapWordSize); 6514 } 6515 _hrm.allocate_free_regions_starting_at(index, 1); 6516 return region_at(index); 6517 } 6518 return NULL; 6519 } 6520 6521 // Heap region set verification 6522 6523 class VerifyRegionListsClosure : public HeapRegionClosure { 6524 private: 6525 HeapRegionSet* _old_set; 6526 HeapRegionSet* _humongous_set; 6527 HeapRegionManager* _hrm; 6528 6529 public: 6530 HeapRegionSetCount _old_count; 6531 HeapRegionSetCount _humongous_count; 6532 HeapRegionSetCount _free_count; 6533 6534 VerifyRegionListsClosure(HeapRegionSet* old_set, 6535 HeapRegionSet* humongous_set, 6536 HeapRegionManager* hrm) : 6537 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm), 6538 _old_count(), _humongous_count(), _free_count(){ } 6539 6540 bool doHeapRegion(HeapRegion* hr) { 6541 if (hr->is_continues_humongous()) { 6542 return false; 6543 } 6544 6545 if (hr->is_young()) { 6546 // TODO 6547 } else if (hr->is_starts_humongous()) { 6548 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index())); 6549 _humongous_count.increment(1u, hr->capacity()); 6550 } else if (hr->is_empty()) { 6551 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index())); 6552 _free_count.increment(1u, hr->capacity()); 6553 } else if (hr->is_old()) { 6554 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index())); 6555 _old_count.increment(1u, hr->capacity()); 6556 } else { 6557 // There are no other valid region types. Check for one invalid 6558 // one we can identify: pinned without old or humongous set. 6559 assert(!hr->is_pinned(), err_msg("Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index())); 6560 ShouldNotReachHere(); 6561 } 6562 return false; 6563 } 6564 6565 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) { 6566 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 6567 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6568 old_set->total_capacity_bytes(), _old_count.capacity())); 6569 6570 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 6571 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6572 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 6573 6574 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())); 6575 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6576 free_list->total_capacity_bytes(), _free_count.capacity())); 6577 } 6578 }; 6579 6580 void G1CollectedHeap::verify_region_sets() { 6581 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6582 6583 // First, check the explicit lists. 6584 _hrm.verify(); 6585 { 6586 // Given that a concurrent operation might be adding regions to 6587 // the secondary free list we have to take the lock before 6588 // verifying it. 6589 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6590 _secondary_free_list.verify_list(); 6591 } 6592 6593 // If a concurrent region freeing operation is in progress it will 6594 // be difficult to correctly attributed any free regions we come 6595 // across to the correct free list given that they might belong to 6596 // one of several (free_list, secondary_free_list, any local lists, 6597 // etc.). So, if that's the case we will skip the rest of the 6598 // verification operation. Alternatively, waiting for the concurrent 6599 // operation to complete will have a non-trivial effect on the GC's 6600 // operation (no concurrent operation will last longer than the 6601 // interval between two calls to verification) and it might hide 6602 // any issues that we would like to catch during testing. 6603 if (free_regions_coming()) { 6604 return; 6605 } 6606 6607 // Make sure we append the secondary_free_list on the free_list so 6608 // that all free regions we will come across can be safely 6609 // attributed to the free_list. 6610 append_secondary_free_list_if_not_empty_with_lock(); 6611 6612 // Finally, make sure that the region accounting in the lists is 6613 // consistent with what we see in the heap. 6614 6615 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm); 6616 heap_region_iterate(&cl); 6617 cl.verify_counts(&_old_set, &_humongous_set, &_hrm); 6618 } 6619 6620 // Optimized nmethod scanning 6621 6622 class RegisterNMethodOopClosure: public OopClosure { 6623 G1CollectedHeap* _g1h; 6624 nmethod* _nm; 6625 6626 template <class T> void do_oop_work(T* p) { 6627 T heap_oop = oopDesc::load_heap_oop(p); 6628 if (!oopDesc::is_null(heap_oop)) { 6629 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6630 HeapRegion* hr = _g1h->heap_region_containing(obj); 6631 assert(!hr->is_continues_humongous(), 6632 err_msg("trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 6633 " starting at " HR_FORMAT, 6634 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6635 6636 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 6637 hr->add_strong_code_root_locked(_nm); 6638 } 6639 } 6640 6641 public: 6642 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6643 _g1h(g1h), _nm(nm) {} 6644 6645 void do_oop(oop* p) { do_oop_work(p); } 6646 void do_oop(narrowOop* p) { do_oop_work(p); } 6647 }; 6648 6649 class UnregisterNMethodOopClosure: public OopClosure { 6650 G1CollectedHeap* _g1h; 6651 nmethod* _nm; 6652 6653 template <class T> void do_oop_work(T* p) { 6654 T heap_oop = oopDesc::load_heap_oop(p); 6655 if (!oopDesc::is_null(heap_oop)) { 6656 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6657 HeapRegion* hr = _g1h->heap_region_containing(obj); 6658 assert(!hr->is_continues_humongous(), 6659 err_msg("trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 6660 " starting at " HR_FORMAT, 6661 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6662 6663 hr->remove_strong_code_root(_nm); 6664 } 6665 } 6666 6667 public: 6668 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6669 _g1h(g1h), _nm(nm) {} 6670 6671 void do_oop(oop* p) { do_oop_work(p); } 6672 void do_oop(narrowOop* p) { do_oop_work(p); } 6673 }; 6674 6675 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6676 CollectedHeap::register_nmethod(nm); 6677 6678 guarantee(nm != NULL, "sanity"); 6679 RegisterNMethodOopClosure reg_cl(this, nm); 6680 nm->oops_do(®_cl); 6681 } 6682 6683 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6684 CollectedHeap::unregister_nmethod(nm); 6685 6686 guarantee(nm != NULL, "sanity"); 6687 UnregisterNMethodOopClosure reg_cl(this, nm); 6688 nm->oops_do(®_cl, true); 6689 } 6690 6691 void G1CollectedHeap::purge_code_root_memory() { 6692 double purge_start = os::elapsedTime(); 6693 G1CodeRootSet::purge(); 6694 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6695 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6696 } 6697 6698 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6699 G1CollectedHeap* _g1h; 6700 6701 public: 6702 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6703 _g1h(g1h) {} 6704 6705 void do_code_blob(CodeBlob* cb) { 6706 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6707 if (nm == NULL) { 6708 return; 6709 } 6710 6711 if (ScavengeRootsInCode) { 6712 _g1h->register_nmethod(nm); 6713 } 6714 } 6715 }; 6716 6717 void G1CollectedHeap::rebuild_strong_code_roots() { 6718 RebuildStrongCodeRootClosure blob_cl(this); 6719 CodeCache::blobs_do(&blob_cl); 6720 }