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 #include "tracefiles/traceEventClasses.hpp" 73 74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 75 76 // turn it on so that the contents of the young list (scan-only / 77 // to-be-collected) are printed at "strategic" points before / during 78 // / after the collection --- this is useful for debugging 79 #define YOUNG_LIST_VERBOSE 0 80 // CURRENT STATUS 81 // This file is under construction. Search for "FIXME". 82 83 // INVARIANTS/NOTES 84 // 85 // All allocation activity covered by the G1CollectedHeap interface is 86 // serialized by acquiring the HeapLock. This happens in mem_allocate 87 // and allocate_new_tlab, which are the "entry" points to the 88 // allocation code from the rest of the JVM. (Note that this does not 89 // apply to TLAB allocation, which is not part of this interface: it 90 // is done by clients of this interface.) 91 92 // Local to this file. 93 94 class RefineCardTableEntryClosure: public CardTableEntryClosure { 95 bool _concurrent; 96 public: 97 RefineCardTableEntryClosure() : _concurrent(true) { } 98 99 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 100 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 101 // This path is executed by the concurrent refine or mutator threads, 102 // concurrently, and so we do not care if card_ptr contains references 103 // that point into the collection set. 104 assert(!oops_into_cset, "should be"); 105 106 if (_concurrent && SuspendibleThreadSet::should_yield()) { 107 // Caller will actually yield. 108 return false; 109 } 110 // Otherwise, we finished successfully; return true. 111 return true; 112 } 113 114 void set_concurrent(bool b) { _concurrent = b; } 115 }; 116 117 118 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 119 private: 120 size_t _num_processed; 121 122 public: 123 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { } 124 125 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 126 *card_ptr = CardTableModRefBS::dirty_card_val(); 127 _num_processed++; 128 return true; 129 } 130 131 size_t num_processed() const { return _num_processed; } 132 }; 133 134 YoungList::YoungList(G1CollectedHeap* g1h) : 135 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 136 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 137 guarantee(check_list_empty(false), "just making sure..."); 138 } 139 140 void YoungList::push_region(HeapRegion *hr) { 141 assert(!hr->is_young(), "should not already be young"); 142 assert(hr->get_next_young_region() == NULL, "cause it should!"); 143 144 hr->set_next_young_region(_head); 145 _head = hr; 146 147 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 148 ++_length; 149 } 150 151 void YoungList::add_survivor_region(HeapRegion* hr) { 152 assert(hr->is_survivor(), "should be flagged as survivor region"); 153 assert(hr->get_next_young_region() == NULL, "cause it should!"); 154 155 hr->set_next_young_region(_survivor_head); 156 if (_survivor_head == NULL) { 157 _survivor_tail = hr; 158 } 159 _survivor_head = hr; 160 ++_survivor_length; 161 } 162 163 void YoungList::empty_list(HeapRegion* list) { 164 while (list != NULL) { 165 HeapRegion* next = list->get_next_young_region(); 166 list->set_next_young_region(NULL); 167 list->uninstall_surv_rate_group(); 168 // This is called before a Full GC and all the non-empty / 169 // non-humongous regions at the end of the Full GC will end up as 170 // old anyway. 171 list->set_old(); 172 list = next; 173 } 174 } 175 176 void YoungList::empty_list() { 177 assert(check_list_well_formed(), "young list should be well formed"); 178 179 empty_list(_head); 180 _head = NULL; 181 _length = 0; 182 183 empty_list(_survivor_head); 184 _survivor_head = NULL; 185 _survivor_tail = NULL; 186 _survivor_length = 0; 187 188 _last_sampled_rs_lengths = 0; 189 190 assert(check_list_empty(false), "just making sure..."); 191 } 192 193 bool YoungList::check_list_well_formed() { 194 bool ret = true; 195 196 uint length = 0; 197 HeapRegion* curr = _head; 198 HeapRegion* last = NULL; 199 while (curr != NULL) { 200 if (!curr->is_young()) { 201 gclog_or_tty->print_cr("### YOUNG REGION " PTR_FORMAT "-" PTR_FORMAT " " 202 "incorrectly tagged (y: %d, surv: %d)", 203 p2i(curr->bottom()), p2i(curr->end()), 204 curr->is_young(), curr->is_survivor()); 205 ret = false; 206 } 207 ++length; 208 last = curr; 209 curr = curr->get_next_young_region(); 210 } 211 ret = ret && (length == _length); 212 213 if (!ret) { 214 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 215 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 216 length, _length); 217 } 218 219 return ret; 220 } 221 222 bool YoungList::check_list_empty(bool check_sample) { 223 bool ret = true; 224 225 if (_length != 0) { 226 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 227 _length); 228 ret = false; 229 } 230 if (check_sample && _last_sampled_rs_lengths != 0) { 231 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 232 ret = false; 233 } 234 if (_head != NULL) { 235 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 236 ret = false; 237 } 238 if (!ret) { 239 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 240 } 241 242 return ret; 243 } 244 245 void 246 YoungList::rs_length_sampling_init() { 247 _sampled_rs_lengths = 0; 248 _curr = _head; 249 } 250 251 bool 252 YoungList::rs_length_sampling_more() { 253 return _curr != NULL; 254 } 255 256 void 257 YoungList::rs_length_sampling_next() { 258 assert( _curr != NULL, "invariant" ); 259 size_t rs_length = _curr->rem_set()->occupied(); 260 261 _sampled_rs_lengths += rs_length; 262 263 // The current region may not yet have been added to the 264 // incremental collection set (it gets added when it is 265 // retired as the current allocation region). 266 if (_curr->in_collection_set()) { 267 // Update the collection set policy information for this region 268 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 269 } 270 271 _curr = _curr->get_next_young_region(); 272 if (_curr == NULL) { 273 _last_sampled_rs_lengths = _sampled_rs_lengths; 274 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 275 } 276 } 277 278 void 279 YoungList::reset_auxilary_lists() { 280 guarantee( is_empty(), "young list should be empty" ); 281 assert(check_list_well_formed(), "young list should be well formed"); 282 283 // Add survivor regions to SurvRateGroup. 284 _g1h->g1_policy()->note_start_adding_survivor_regions(); 285 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 286 287 int young_index_in_cset = 0; 288 for (HeapRegion* curr = _survivor_head; 289 curr != NULL; 290 curr = curr->get_next_young_region()) { 291 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 292 293 // The region is a non-empty survivor so let's add it to 294 // the incremental collection set for the next evacuation 295 // pause. 296 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 297 young_index_in_cset += 1; 298 } 299 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 300 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 301 302 _head = _survivor_head; 303 _length = _survivor_length; 304 if (_survivor_head != NULL) { 305 assert(_survivor_tail != NULL, "cause it shouldn't be"); 306 assert(_survivor_length > 0, "invariant"); 307 _survivor_tail->set_next_young_region(NULL); 308 } 309 310 // Don't clear the survivor list handles until the start of 311 // the next evacuation pause - we need it in order to re-tag 312 // the survivor regions from this evacuation pause as 'young' 313 // at the start of the next. 314 315 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 316 317 assert(check_list_well_formed(), "young list should be well formed"); 318 } 319 320 void YoungList::print() { 321 HeapRegion* lists[] = {_head, _survivor_head}; 322 const char* names[] = {"YOUNG", "SURVIVOR"}; 323 324 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) { 325 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 326 HeapRegion *curr = lists[list]; 327 if (curr == NULL) 328 gclog_or_tty->print_cr(" empty"); 329 while (curr != NULL) { 330 gclog_or_tty->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT ", N: " PTR_FORMAT ", age: %4d", 331 HR_FORMAT_PARAMS(curr), 332 p2i(curr->prev_top_at_mark_start()), 333 p2i(curr->next_top_at_mark_start()), 334 curr->age_in_surv_rate_group_cond()); 335 curr = curr->get_next_young_region(); 336 } 337 } 338 339 gclog_or_tty->cr(); 340 } 341 342 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 343 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 344 } 345 346 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 347 // The from card cache is not the memory that is actually committed. So we cannot 348 // take advantage of the zero_filled parameter. 349 reset_from_card_cache(start_idx, num_regions); 350 } 351 352 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 353 { 354 // Claim the right to put the region on the dirty cards region list 355 // by installing a self pointer. 356 HeapRegion* next = hr->get_next_dirty_cards_region(); 357 if (next == NULL) { 358 HeapRegion* res = (HeapRegion*) 359 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 360 NULL); 361 if (res == NULL) { 362 HeapRegion* head; 363 do { 364 // Put the region to the dirty cards region list. 365 head = _dirty_cards_region_list; 366 next = (HeapRegion*) 367 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 368 if (next == head) { 369 assert(hr->get_next_dirty_cards_region() == hr, 370 "hr->get_next_dirty_cards_region() != hr"); 371 if (next == NULL) { 372 // The last region in the list points to itself. 373 hr->set_next_dirty_cards_region(hr); 374 } else { 375 hr->set_next_dirty_cards_region(next); 376 } 377 } 378 } while (next != head); 379 } 380 } 381 } 382 383 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 384 { 385 HeapRegion* head; 386 HeapRegion* hr; 387 do { 388 head = _dirty_cards_region_list; 389 if (head == NULL) { 390 return NULL; 391 } 392 HeapRegion* new_head = head->get_next_dirty_cards_region(); 393 if (head == new_head) { 394 // The last region. 395 new_head = NULL; 396 } 397 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 398 head); 399 } while (hr != head); 400 assert(hr != NULL, "invariant"); 401 hr->set_next_dirty_cards_region(NULL); 402 return hr; 403 } 404 405 // Returns true if the reference points to an object that 406 // can move in an incremental collection. 407 bool G1CollectedHeap::is_scavengable(const void* p) { 408 HeapRegion* hr = heap_region_containing(p); 409 return !hr->is_pinned(); 410 } 411 412 // Private methods. 413 414 HeapRegion* 415 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 416 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 417 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 418 if (!_secondary_free_list.is_empty()) { 419 if (G1ConcRegionFreeingVerbose) { 420 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 421 "secondary_free_list has %u entries", 422 _secondary_free_list.length()); 423 } 424 // It looks as if there are free regions available on the 425 // secondary_free_list. Let's move them to the free_list and try 426 // again to allocate from it. 427 append_secondary_free_list(); 428 429 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 430 "empty we should have moved at least one entry to the free_list"); 431 HeapRegion* res = _hrm.allocate_free_region(is_old); 432 if (G1ConcRegionFreeingVerbose) { 433 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 434 "allocated " HR_FORMAT " from secondary_free_list", 435 HR_FORMAT_PARAMS(res)); 436 } 437 return res; 438 } 439 440 // Wait here until we get notified either when (a) there are no 441 // more free regions coming or (b) some regions have been moved on 442 // the secondary_free_list. 443 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 444 } 445 446 if (G1ConcRegionFreeingVerbose) { 447 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 448 "could not allocate from secondary_free_list"); 449 } 450 return NULL; 451 } 452 453 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 454 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 455 "the only time we use this to allocate a humongous region is " 456 "when we are allocating a single humongous region"); 457 458 HeapRegion* res; 459 if (G1StressConcRegionFreeing) { 460 if (!_secondary_free_list.is_empty()) { 461 if (G1ConcRegionFreeingVerbose) { 462 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 463 "forced to look at the secondary_free_list"); 464 } 465 res = new_region_try_secondary_free_list(is_old); 466 if (res != NULL) { 467 return res; 468 } 469 } 470 } 471 472 res = _hrm.allocate_free_region(is_old); 473 474 if (res == NULL) { 475 if (G1ConcRegionFreeingVerbose) { 476 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 477 "res == NULL, trying the secondary_free_list"); 478 } 479 res = new_region_try_secondary_free_list(is_old); 480 } 481 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 482 // Currently, only attempts to allocate GC alloc regions set 483 // do_expand to true. So, we should only reach here during a 484 // safepoint. If this assumption changes we might have to 485 // reconsider the use of _expand_heap_after_alloc_failure. 486 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 487 488 ergo_verbose1(ErgoHeapSizing, 489 "attempt heap expansion", 490 ergo_format_reason("region allocation request failed") 491 ergo_format_byte("allocation request"), 492 word_size * HeapWordSize); 493 if (expand(word_size * HeapWordSize)) { 494 // Given that expand() succeeded in expanding the heap, and we 495 // always expand the heap by an amount aligned to the heap 496 // region size, the free list should in theory not be empty. 497 // In either case allocate_free_region() will check for NULL. 498 res = _hrm.allocate_free_region(is_old); 499 } else { 500 _expand_heap_after_alloc_failure = false; 501 } 502 } 503 return res; 504 } 505 506 HeapWord* 507 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 508 uint num_regions, 509 size_t word_size, 510 AllocationContext_t context) { 511 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 512 assert(is_humongous(word_size), "word_size should be humongous"); 513 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 514 515 // Index of last region in the series + 1. 516 uint last = first + num_regions; 517 518 // We need to initialize the region(s) we just discovered. This is 519 // a bit tricky given that it can happen concurrently with 520 // refinement threads refining cards on these regions and 521 // potentially wanting to refine the BOT as they are scanning 522 // those cards (this can happen shortly after a cleanup; see CR 523 // 6991377). So we have to set up the region(s) carefully and in 524 // a specific order. 525 526 // The word size sum of all the regions we will allocate. 527 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 528 assert(word_size <= word_size_sum, "sanity"); 529 530 // This will be the "starts humongous" region. 531 HeapRegion* first_hr = region_at(first); 532 // The header of the new object will be placed at the bottom of 533 // the first region. 534 HeapWord* new_obj = first_hr->bottom(); 535 // This will be the new end of the first region in the series that 536 // should also match the end of the last region in the series. 537 HeapWord* new_end = new_obj + word_size_sum; 538 // This will be the new top of the first region that will reflect 539 // this allocation. 540 HeapWord* new_top = new_obj + word_size; 541 542 // First, we need to zero the header of the space that we will be 543 // allocating. When we update top further down, some refinement 544 // threads might try to scan the region. By zeroing the header we 545 // ensure that any thread that will try to scan the region will 546 // come across the zero klass word and bail out. 547 // 548 // NOTE: It would not have been correct to have used 549 // CollectedHeap::fill_with_object() and make the space look like 550 // an int array. The thread that is doing the allocation will 551 // later update the object header to a potentially different array 552 // type and, for a very short period of time, the klass and length 553 // fields will be inconsistent. This could cause a refinement 554 // thread to calculate the object size incorrectly. 555 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 556 557 // We will set up the first region as "starts humongous". This 558 // will also update the BOT covering all the regions to reflect 559 // that there is a single object that starts at the bottom of the 560 // first region. 561 first_hr->set_starts_humongous(new_top, new_end); 562 first_hr->set_allocation_context(context); 563 // Then, if there are any, we will set up the "continues 564 // humongous" regions. 565 HeapRegion* hr = NULL; 566 for (uint i = first + 1; i < last; ++i) { 567 hr = region_at(i); 568 hr->set_continues_humongous(first_hr); 569 hr->set_allocation_context(context); 570 } 571 // If we have "continues humongous" regions (hr != NULL), then the 572 // end of the last one should match new_end. 573 assert(hr == NULL || hr->end() == new_end, "sanity"); 574 575 // Up to this point no concurrent thread would have been able to 576 // do any scanning on any region in this series. All the top 577 // fields still point to bottom, so the intersection between 578 // [bottom,top] and [card_start,card_end] will be empty. Before we 579 // update the top fields, we'll do a storestore to make sure that 580 // no thread sees the update to top before the zeroing of the 581 // object header and the BOT initialization. 582 OrderAccess::storestore(); 583 584 // Now that the BOT and the object header have been initialized, 585 // we can update top of the "starts humongous" region. 586 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 587 "new_top should be in this region"); 588 first_hr->set_top(new_top); 589 if (_hr_printer.is_active()) { 590 HeapWord* bottom = first_hr->bottom(); 591 HeapWord* end = first_hr->orig_end(); 592 if ((first + 1) == last) { 593 // the series has a single humongous region 594 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 595 } else { 596 // the series has more than one humongous regions 597 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 598 } 599 } 600 601 // Now, we will update the top fields of the "continues humongous" 602 // regions. The reason we need to do this is that, otherwise, 603 // these regions would look empty and this will confuse parts of 604 // G1. For example, the code that looks for a consecutive number 605 // of empty regions will consider them empty and try to 606 // re-allocate them. We can extend is_empty() to also include 607 // !is_continues_humongous(), but it is easier to just update the top 608 // fields here. The way we set top for all regions (i.e., top == 609 // end for all regions but the last one, top == new_top for the 610 // last one) is actually used when we will free up the humongous 611 // region in free_humongous_region(). 612 hr = NULL; 613 for (uint i = first + 1; i < last; ++i) { 614 hr = region_at(i); 615 if ((i + 1) == last) { 616 // last continues humongous region 617 assert(hr->bottom() < new_top && new_top <= hr->end(), 618 "new_top should fall on this region"); 619 hr->set_top(new_top); 620 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 621 } else { 622 // not last one 623 assert(new_top > hr->end(), "new_top should be above this region"); 624 hr->set_top(hr->end()); 625 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 626 } 627 } 628 // If we have continues humongous regions (hr != NULL), then the 629 // end of the last one should match new_end and its top should 630 // match new_top. 631 assert(hr == NULL || 632 (hr->end() == new_end && hr->top() == new_top), "sanity"); 633 check_bitmaps("Humongous Region Allocation", first_hr); 634 635 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 636 increase_used(first_hr->used()); 637 _humongous_set.add(first_hr); 638 639 return new_obj; 640 } 641 642 // If could fit into free regions w/o expansion, try. 643 // Otherwise, if can expand, do so. 644 // Otherwise, if using ex regions might help, try with ex given back. 645 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 646 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 647 648 verify_region_sets_optional(); 649 650 uint first = G1_NO_HRM_INDEX; 651 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords); 652 653 if (obj_regions == 1) { 654 // Only one region to allocate, try to use a fast path by directly allocating 655 // from the free lists. Do not try to expand here, we will potentially do that 656 // later. 657 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 658 if (hr != NULL) { 659 first = hr->hrm_index(); 660 } 661 } else { 662 // We can't allocate humongous regions spanning more than one region while 663 // cleanupComplete() is running, since some of the regions we find to be 664 // empty might not yet be added to the free list. It is not straightforward 665 // to know in which list they are on so that we can remove them. We only 666 // need to do this if we need to allocate more than one region to satisfy the 667 // current humongous allocation request. If we are only allocating one region 668 // we use the one-region region allocation code (see above), that already 669 // potentially waits for regions from the secondary free list. 670 wait_while_free_regions_coming(); 671 append_secondary_free_list_if_not_empty_with_lock(); 672 673 // Policy: Try only empty regions (i.e. already committed first). Maybe we 674 // are lucky enough to find some. 675 first = _hrm.find_contiguous_only_empty(obj_regions); 676 if (first != G1_NO_HRM_INDEX) { 677 _hrm.allocate_free_regions_starting_at(first, obj_regions); 678 } 679 } 680 681 if (first == G1_NO_HRM_INDEX) { 682 // Policy: We could not find enough regions for the humongous object in the 683 // free list. Look through the heap to find a mix of free and uncommitted regions. 684 // If so, try expansion. 685 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 686 if (first != G1_NO_HRM_INDEX) { 687 // We found something. Make sure these regions are committed, i.e. expand 688 // the heap. Alternatively we could do a defragmentation GC. 689 ergo_verbose1(ErgoHeapSizing, 690 "attempt heap expansion", 691 ergo_format_reason("humongous allocation request failed") 692 ergo_format_byte("allocation request"), 693 word_size * HeapWordSize); 694 695 _hrm.expand_at(first, obj_regions); 696 g1_policy()->record_new_heap_size(num_regions()); 697 698 #ifdef ASSERT 699 for (uint i = first; i < first + obj_regions; ++i) { 700 HeapRegion* hr = region_at(i); 701 assert(hr->is_free(), "sanity"); 702 assert(hr->is_empty(), "sanity"); 703 assert(is_on_master_free_list(hr), "sanity"); 704 } 705 #endif 706 _hrm.allocate_free_regions_starting_at(first, obj_regions); 707 } else { 708 // Policy: Potentially trigger a defragmentation GC. 709 } 710 } 711 712 HeapWord* result = NULL; 713 if (first != G1_NO_HRM_INDEX) { 714 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 715 word_size, context); 716 assert(result != NULL, "it should always return a valid result"); 717 718 // A successful humongous object allocation changes the used space 719 // information of the old generation so we need to recalculate the 720 // sizes and update the jstat counters here. 721 g1mm()->update_sizes(); 722 } 723 724 verify_region_sets_optional(); 725 726 return result; 727 } 728 729 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 730 assert_heap_not_locked_and_not_at_safepoint(); 731 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 732 733 uint dummy_gc_count_before; 734 uint dummy_gclocker_retry_count = 0; 735 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 736 } 737 738 HeapWord* 739 G1CollectedHeap::mem_allocate(size_t word_size, 740 bool* gc_overhead_limit_was_exceeded) { 741 assert_heap_not_locked_and_not_at_safepoint(); 742 743 // Loop until the allocation is satisfied, or unsatisfied after GC. 744 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 745 uint gc_count_before; 746 747 HeapWord* result = NULL; 748 if (!is_humongous(word_size)) { 749 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 750 } else { 751 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 752 } 753 if (result != NULL) { 754 return result; 755 } 756 757 // Create the garbage collection operation... 758 VM_G1CollectForAllocation op(gc_count_before, word_size); 759 op.set_allocation_context(AllocationContext::current()); 760 761 // ...and get the VM thread to execute it. 762 VMThread::execute(&op); 763 764 if (op.prologue_succeeded() && op.pause_succeeded()) { 765 // If the operation was successful we'll return the result even 766 // if it is NULL. If the allocation attempt failed immediately 767 // after a Full GC, it's unlikely we'll be able to allocate now. 768 HeapWord* result = op.result(); 769 if (result != NULL && !is_humongous(word_size)) { 770 // Allocations that take place on VM operations do not do any 771 // card dirtying and we have to do it here. We only have to do 772 // this for non-humongous allocations, though. 773 dirty_young_block(result, word_size); 774 } 775 return result; 776 } else { 777 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 778 return NULL; 779 } 780 assert(op.result() == NULL, 781 "the result should be NULL if the VM op did not succeed"); 782 } 783 784 // Give a warning if we seem to be looping forever. 785 if ((QueuedAllocationWarningCount > 0) && 786 (try_count % QueuedAllocationWarningCount == 0)) { 787 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 788 } 789 } 790 791 ShouldNotReachHere(); 792 return NULL; 793 } 794 795 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 796 AllocationContext_t context, 797 uint* gc_count_before_ret, 798 uint* gclocker_retry_count_ret) { 799 // Make sure you read the note in attempt_allocation_humongous(). 800 801 assert_heap_not_locked_and_not_at_safepoint(); 802 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 803 "be called for humongous allocation requests"); 804 805 // We should only get here after the first-level allocation attempt 806 // (attempt_allocation()) failed to allocate. 807 808 // We will loop until a) we manage to successfully perform the 809 // allocation or b) we successfully schedule a collection which 810 // fails to perform the allocation. b) is the only case when we'll 811 // return NULL. 812 HeapWord* result = NULL; 813 for (int try_count = 1; /* we'll return */; try_count += 1) { 814 bool should_try_gc; 815 uint gc_count_before; 816 817 { 818 MutexLockerEx x(Heap_lock); 819 result = _allocator->attempt_allocation_locked(word_size, context); 820 if (result != NULL) { 821 return result; 822 } 823 824 if (GC_locker::is_active_and_needs_gc()) { 825 if (g1_policy()->can_expand_young_list()) { 826 // No need for an ergo verbose message here, 827 // can_expand_young_list() does this when it returns true. 828 result = _allocator->attempt_allocation_force(word_size, context); 829 if (result != NULL) { 830 return result; 831 } 832 } 833 should_try_gc = false; 834 } else { 835 // The GCLocker may not be active but the GCLocker initiated 836 // GC may not yet have been performed (GCLocker::needs_gc() 837 // returns true). In this case we do not try this GC and 838 // wait until the GCLocker initiated GC is performed, and 839 // then retry the allocation. 840 if (GC_locker::needs_gc()) { 841 should_try_gc = false; 842 } else { 843 // Read the GC count while still holding the Heap_lock. 844 gc_count_before = total_collections(); 845 should_try_gc = true; 846 } 847 } 848 } 849 850 if (should_try_gc) { 851 bool succeeded; 852 result = do_collection_pause(word_size, gc_count_before, &succeeded, 853 GCCause::_g1_inc_collection_pause); 854 if (result != NULL) { 855 assert(succeeded, "only way to get back a non-NULL result"); 856 return result; 857 } 858 859 if (succeeded) { 860 // If we get here we successfully scheduled a collection which 861 // failed to allocate. No point in trying to allocate 862 // further. We'll just return NULL. 863 MutexLockerEx x(Heap_lock); 864 *gc_count_before_ret = total_collections(); 865 return NULL; 866 } 867 } else { 868 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 869 MutexLockerEx x(Heap_lock); 870 *gc_count_before_ret = total_collections(); 871 return NULL; 872 } 873 // The GCLocker is either active or the GCLocker initiated 874 // GC has not yet been performed. Stall until it is and 875 // then retry the allocation. 876 GC_locker::stall_until_clear(); 877 (*gclocker_retry_count_ret) += 1; 878 } 879 880 // We can reach here if we were unsuccessful in scheduling a 881 // collection (because another thread beat us to it) or if we were 882 // stalled due to the GC locker. In either can we should retry the 883 // allocation attempt in case another thread successfully 884 // performed a collection and reclaimed enough space. We do the 885 // first attempt (without holding the Heap_lock) here and the 886 // follow-on attempt will be at the start of the next loop 887 // iteration (after taking the Heap_lock). 888 result = _allocator->attempt_allocation(word_size, context); 889 if (result != NULL) { 890 return result; 891 } 892 893 // Give a warning if we seem to be looping forever. 894 if ((QueuedAllocationWarningCount > 0) && 895 (try_count % QueuedAllocationWarningCount == 0)) { 896 warning("G1CollectedHeap::attempt_allocation_slow() " 897 "retries %d times", try_count); 898 } 899 } 900 901 ShouldNotReachHere(); 902 return NULL; 903 } 904 905 void G1CollectedHeap::begin_archive_alloc_range() { 906 assert_at_safepoint(true /* should_be_vm_thread */); 907 if (_archive_allocator == NULL) { 908 _archive_allocator = G1ArchiveAllocator::create_allocator(this); 909 } 910 } 911 912 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 913 // Allocations in archive regions cannot be of a size that would be considered 914 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 915 // may be different at archive-restore time. 916 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 917 } 918 919 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 920 assert_at_safepoint(true /* should_be_vm_thread */); 921 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 922 if (is_archive_alloc_too_large(word_size)) { 923 return NULL; 924 } 925 return _archive_allocator->archive_mem_allocate(word_size); 926 } 927 928 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 929 size_t end_alignment_in_bytes) { 930 assert_at_safepoint(true /* should_be_vm_thread */); 931 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 932 933 // Call complete_archive to do the real work, filling in the MemRegion 934 // array with the archive regions. 935 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 936 delete _archive_allocator; 937 _archive_allocator = NULL; 938 } 939 940 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 941 assert(ranges != NULL, "MemRegion array NULL"); 942 assert(count != 0, "No MemRegions provided"); 943 MemRegion reserved = _hrm.reserved(); 944 for (size_t i = 0; i < count; i++) { 945 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 946 return false; 947 } 948 } 949 return true; 950 } 951 952 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) { 953 assert(ranges != NULL, "MemRegion array NULL"); 954 assert(count != 0, "No MemRegions provided"); 955 MutexLockerEx x(Heap_lock); 956 957 MemRegion reserved = _hrm.reserved(); 958 HeapWord* prev_last_addr = NULL; 959 HeapRegion* prev_last_region = NULL; 960 961 // Temporarily disable pretouching of heap pages. This interface is used 962 // when mmap'ing archived heap data in, so pre-touching is wasted. 963 FlagSetting fs(AlwaysPreTouch, false); 964 965 // Enable archive object checking in G1MarkSweep. We have to let it know 966 // about each archive range, so that objects in those ranges aren't marked. 967 G1MarkSweep::enable_archive_object_check(); 968 969 // For each specified MemRegion range, allocate the corresponding G1 970 // regions and mark them as archive regions. We expect the ranges in 971 // ascending starting address order, without overlap. 972 for (size_t i = 0; i < count; i++) { 973 MemRegion curr_range = ranges[i]; 974 HeapWord* start_address = curr_range.start(); 975 size_t word_size = curr_range.word_size(); 976 HeapWord* last_address = curr_range.last(); 977 size_t commits = 0; 978 979 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 980 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 981 p2i(start_address), p2i(last_address))); 982 guarantee(start_address > prev_last_addr, 983 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 984 p2i(start_address), p2i(prev_last_addr))); 985 prev_last_addr = last_address; 986 987 // Check for ranges that start in the same G1 region in which the previous 988 // range ended, and adjust the start address so we don't try to allocate 989 // the same region again. If the current range is entirely within that 990 // region, skip it, just adjusting the recorded top. 991 HeapRegion* start_region = _hrm.addr_to_region(start_address); 992 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 993 start_address = start_region->end(); 994 if (start_address > last_address) { 995 increase_used(word_size * HeapWordSize); 996 start_region->set_top(last_address + 1); 997 continue; 998 } 999 start_region->set_top(start_address); 1000 curr_range = MemRegion(start_address, last_address + 1); 1001 start_region = _hrm.addr_to_region(start_address); 1002 } 1003 1004 // Perform the actual region allocation, exiting if it fails. 1005 // Then note how much new space we have allocated. 1006 if (!_hrm.allocate_containing_regions(curr_range, &commits)) { 1007 return false; 1008 } 1009 increase_used(word_size * HeapWordSize); 1010 if (commits != 0) { 1011 ergo_verbose1(ErgoHeapSizing, 1012 "attempt heap expansion", 1013 ergo_format_reason("allocate archive regions") 1014 ergo_format_byte("total size"), 1015 HeapRegion::GrainWords * HeapWordSize * commits); 1016 } 1017 1018 // Mark each G1 region touched by the range as archive, add it to the old set, 1019 // and set the allocation context and top. 1020 HeapRegion* curr_region = _hrm.addr_to_region(start_address); 1021 HeapRegion* last_region = _hrm.addr_to_region(last_address); 1022 prev_last_region = last_region; 1023 1024 while (curr_region != NULL) { 1025 assert(curr_region->is_empty() && !curr_region->is_pinned(), 1026 err_msg("Region already in use (index %u)", curr_region->hrm_index())); 1027 _hr_printer.alloc(curr_region, G1HRPrinter::Archive); 1028 curr_region->set_allocation_context(AllocationContext::system()); 1029 curr_region->set_archive(); 1030 _old_set.add(curr_region); 1031 if (curr_region != last_region) { 1032 curr_region->set_top(curr_region->end()); 1033 curr_region = _hrm.next_region_in_heap(curr_region); 1034 } else { 1035 curr_region->set_top(last_address + 1); 1036 curr_region = NULL; 1037 } 1038 } 1039 1040 // Notify mark-sweep of the archive range. 1041 G1MarkSweep::mark_range_archive(curr_range); 1042 } 1043 return true; 1044 } 1045 1046 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 1047 assert(ranges != NULL, "MemRegion array NULL"); 1048 assert(count != 0, "No MemRegions provided"); 1049 MemRegion reserved = _hrm.reserved(); 1050 HeapWord *prev_last_addr = NULL; 1051 HeapRegion* prev_last_region = NULL; 1052 1053 // For each MemRegion, create filler objects, if needed, in the G1 regions 1054 // that contain the address range. The address range actually within the 1055 // MemRegion will not be modified. That is assumed to have been initialized 1056 // elsewhere, probably via an mmap of archived heap data. 1057 MutexLockerEx x(Heap_lock); 1058 for (size_t i = 0; i < count; i++) { 1059 HeapWord* start_address = ranges[i].start(); 1060 HeapWord* last_address = ranges[i].last(); 1061 1062 assert(reserved.contains(start_address) && reserved.contains(last_address), 1063 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 1064 p2i(start_address), p2i(last_address))); 1065 assert(start_address > prev_last_addr, 1066 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 1067 p2i(start_address), p2i(prev_last_addr))); 1068 1069 HeapRegion* start_region = _hrm.addr_to_region(start_address); 1070 HeapRegion* last_region = _hrm.addr_to_region(last_address); 1071 HeapWord* bottom_address = start_region->bottom(); 1072 1073 // Check for a range beginning in the same region in which the 1074 // previous one ended. 1075 if (start_region == prev_last_region) { 1076 bottom_address = prev_last_addr + 1; 1077 } 1078 1079 // Verify that the regions were all marked as archive regions by 1080 // alloc_archive_regions. 1081 HeapRegion* curr_region = start_region; 1082 while (curr_region != NULL) { 1083 guarantee(curr_region->is_archive(), 1084 err_msg("Expected archive region at index %u", curr_region->hrm_index())); 1085 if (curr_region != last_region) { 1086 curr_region = _hrm.next_region_in_heap(curr_region); 1087 } else { 1088 curr_region = NULL; 1089 } 1090 } 1091 1092 prev_last_addr = last_address; 1093 prev_last_region = last_region; 1094 1095 // Fill the memory below the allocated range with dummy object(s), 1096 // if the region bottom does not match the range start, or if the previous 1097 // range ended within the same G1 region, and there is a gap. 1098 if (start_address != bottom_address) { 1099 size_t fill_size = pointer_delta(start_address, bottom_address); 1100 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 1101 increase_used(fill_size * HeapWordSize); 1102 } 1103 } 1104 } 1105 1106 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size, 1107 uint* gc_count_before_ret, 1108 uint* gclocker_retry_count_ret) { 1109 assert_heap_not_locked_and_not_at_safepoint(); 1110 assert(!is_humongous(word_size), "attempt_allocation() should not " 1111 "be called for humongous allocation requests"); 1112 1113 AllocationContext_t context = AllocationContext::current(); 1114 HeapWord* result = _allocator->attempt_allocation(word_size, context); 1115 1116 if (result == NULL) { 1117 result = attempt_allocation_slow(word_size, 1118 context, 1119 gc_count_before_ret, 1120 gclocker_retry_count_ret); 1121 } 1122 assert_heap_not_locked(); 1123 if (result != NULL) { 1124 dirty_young_block(result, word_size); 1125 } 1126 return result; 1127 } 1128 1129 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 1130 uint* gc_count_before_ret, 1131 uint* gclocker_retry_count_ret) { 1132 // The structure of this method has a lot of similarities to 1133 // attempt_allocation_slow(). The reason these two were not merged 1134 // into a single one is that such a method would require several "if 1135 // allocation is not humongous do this, otherwise do that" 1136 // conditional paths which would obscure its flow. In fact, an early 1137 // version of this code did use a unified method which was harder to 1138 // follow and, as a result, it had subtle bugs that were hard to 1139 // track down. So keeping these two methods separate allows each to 1140 // be more readable. It will be good to keep these two in sync as 1141 // much as possible. 1142 1143 assert_heap_not_locked_and_not_at_safepoint(); 1144 assert(is_humongous(word_size), "attempt_allocation_humongous() " 1145 "should only be called for humongous allocations"); 1146 1147 // Humongous objects can exhaust the heap quickly, so we should check if we 1148 // need to start a marking cycle at each humongous object allocation. We do 1149 // the check before we do the actual allocation. The reason for doing it 1150 // before the allocation is that we avoid having to keep track of the newly 1151 // allocated memory while we do a GC. 1152 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1153 word_size)) { 1154 collect(GCCause::_g1_humongous_allocation); 1155 } 1156 1157 // We will loop until a) we manage to successfully perform the 1158 // allocation or b) we successfully schedule a collection which 1159 // fails to perform the allocation. b) is the only case when we'll 1160 // return NULL. 1161 HeapWord* result = NULL; 1162 for (int try_count = 1; /* we'll return */; try_count += 1) { 1163 bool should_try_gc; 1164 uint gc_count_before; 1165 1166 { 1167 MutexLockerEx x(Heap_lock); 1168 1169 // Given that humongous objects are not allocated in young 1170 // regions, we'll first try to do the allocation without doing a 1171 // collection hoping that there's enough space in the heap. 1172 result = humongous_obj_allocate(word_size, AllocationContext::current()); 1173 if (result != NULL) { 1174 return result; 1175 } 1176 1177 if (GC_locker::is_active_and_needs_gc()) { 1178 should_try_gc = false; 1179 } else { 1180 // The GCLocker may not be active but the GCLocker initiated 1181 // GC may not yet have been performed (GCLocker::needs_gc() 1182 // returns true). In this case we do not try this GC and 1183 // wait until the GCLocker initiated GC is performed, and 1184 // then retry the allocation. 1185 if (GC_locker::needs_gc()) { 1186 should_try_gc = false; 1187 } else { 1188 // Read the GC count while still holding the Heap_lock. 1189 gc_count_before = total_collections(); 1190 should_try_gc = true; 1191 } 1192 } 1193 } 1194 1195 if (should_try_gc) { 1196 // If we failed to allocate the humongous object, we should try to 1197 // do a collection pause (if we're allowed) in case it reclaims 1198 // enough space for the allocation to succeed after the pause. 1199 1200 bool succeeded; 1201 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1202 GCCause::_g1_humongous_allocation); 1203 if (result != NULL) { 1204 assert(succeeded, "only way to get back a non-NULL result"); 1205 return result; 1206 } 1207 1208 if (succeeded) { 1209 // If we get here we successfully scheduled a collection which 1210 // failed to allocate. No point in trying to allocate 1211 // further. We'll just return NULL. 1212 MutexLockerEx x(Heap_lock); 1213 *gc_count_before_ret = total_collections(); 1214 return NULL; 1215 } 1216 } else { 1217 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1218 MutexLockerEx x(Heap_lock); 1219 *gc_count_before_ret = total_collections(); 1220 return NULL; 1221 } 1222 // The GCLocker is either active or the GCLocker initiated 1223 // GC has not yet been performed. Stall until it is and 1224 // then retry the allocation. 1225 GC_locker::stall_until_clear(); 1226 (*gclocker_retry_count_ret) += 1; 1227 } 1228 1229 // We can reach here if we were unsuccessful in scheduling a 1230 // collection (because another thread beat us to it) or if we were 1231 // stalled due to the GC locker. In either can we should retry the 1232 // allocation attempt in case another thread successfully 1233 // performed a collection and reclaimed enough space. Give a 1234 // warning if we seem to be looping forever. 1235 1236 if ((QueuedAllocationWarningCount > 0) && 1237 (try_count % QueuedAllocationWarningCount == 0)) { 1238 warning("G1CollectedHeap::attempt_allocation_humongous() " 1239 "retries %d times", try_count); 1240 } 1241 } 1242 1243 ShouldNotReachHere(); 1244 return NULL; 1245 } 1246 1247 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1248 AllocationContext_t context, 1249 bool expect_null_mutator_alloc_region) { 1250 assert_at_safepoint(true /* should_be_vm_thread */); 1251 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region, 1252 "the current alloc region was unexpectedly found to be non-NULL"); 1253 1254 if (!is_humongous(word_size)) { 1255 return _allocator->attempt_allocation_locked(word_size, context); 1256 } else { 1257 HeapWord* result = humongous_obj_allocate(word_size, context); 1258 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1259 collector_state()->set_initiate_conc_mark_if_possible(true); 1260 } 1261 return result; 1262 } 1263 1264 ShouldNotReachHere(); 1265 } 1266 1267 class PostMCRemSetClearClosure: public HeapRegionClosure { 1268 G1CollectedHeap* _g1h; 1269 ModRefBarrierSet* _mr_bs; 1270 public: 1271 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1272 _g1h(g1h), _mr_bs(mr_bs) {} 1273 1274 bool doHeapRegion(HeapRegion* r) { 1275 HeapRegionRemSet* hrrs = r->rem_set(); 1276 1277 if (r->is_continues_humongous()) { 1278 // We'll assert that the strong code root list and RSet is empty 1279 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1280 assert(hrrs->occupied() == 0, "RSet should be empty"); 1281 return false; 1282 } 1283 1284 _g1h->reset_gc_time_stamps(r); 1285 hrrs->clear(); 1286 // You might think here that we could clear just the cards 1287 // corresponding to the used region. But no: if we leave a dirty card 1288 // in a region we might allocate into, then it would prevent that card 1289 // from being enqueued, and cause it to be missed. 1290 // Re: the performance cost: we shouldn't be doing full GC anyway! 1291 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1292 1293 return false; 1294 } 1295 }; 1296 1297 void G1CollectedHeap::clear_rsets_post_compaction() { 1298 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1299 heap_region_iterate(&rs_clear); 1300 } 1301 1302 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1303 G1CollectedHeap* _g1h; 1304 UpdateRSOopClosure _cl; 1305 public: 1306 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) : 1307 _cl(g1->g1_rem_set(), worker_i), 1308 _g1h(g1) 1309 { } 1310 1311 bool doHeapRegion(HeapRegion* r) { 1312 if (!r->is_continues_humongous()) { 1313 _cl.set_from(r); 1314 r->oop_iterate(&_cl); 1315 } 1316 return false; 1317 } 1318 }; 1319 1320 class ParRebuildRSTask: public AbstractGangTask { 1321 G1CollectedHeap* _g1; 1322 HeapRegionClaimer _hrclaimer; 1323 1324 public: 1325 ParRebuildRSTask(G1CollectedHeap* g1) : 1326 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {} 1327 1328 void work(uint worker_id) { 1329 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1330 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer); 1331 } 1332 }; 1333 1334 class PostCompactionPrinterClosure: public HeapRegionClosure { 1335 private: 1336 G1HRPrinter* _hr_printer; 1337 public: 1338 bool doHeapRegion(HeapRegion* hr) { 1339 assert(!hr->is_young(), "not expecting to find young regions"); 1340 if (hr->is_free()) { 1341 // We only generate output for non-empty regions. 1342 } else if (hr->is_starts_humongous()) { 1343 if (hr->region_num() == 1) { 1344 // single humongous region 1345 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1346 } else { 1347 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1348 } 1349 } else if (hr->is_continues_humongous()) { 1350 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1351 } else if (hr->is_archive()) { 1352 _hr_printer->post_compaction(hr, G1HRPrinter::Archive); 1353 } else if (hr->is_old()) { 1354 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1355 } else { 1356 ShouldNotReachHere(); 1357 } 1358 return false; 1359 } 1360 1361 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1362 : _hr_printer(hr_printer) { } 1363 }; 1364 1365 void G1CollectedHeap::print_hrm_post_compaction() { 1366 PostCompactionPrinterClosure cl(hr_printer()); 1367 heap_region_iterate(&cl); 1368 } 1369 1370 bool G1CollectedHeap::do_collection(bool explicit_gc, 1371 bool clear_all_soft_refs, 1372 size_t word_size) { 1373 assert_at_safepoint(true /* should_be_vm_thread */); 1374 1375 if (GC_locker::check_active_before_gc()) { 1376 return false; 1377 } 1378 1379 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1380 gc_timer->register_gc_start(); 1381 1382 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1383 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1384 1385 SvcGCMarker sgcm(SvcGCMarker::FULL); 1386 ResourceMark rm; 1387 1388 G1Log::update_level(); 1389 print_heap_before_gc(); 1390 trace_heap_before_gc(gc_tracer); 1391 1392 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1393 1394 verify_region_sets_optional(); 1395 1396 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1397 collector_policy()->should_clear_all_soft_refs(); 1398 1399 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1400 1401 { 1402 IsGCActiveMark x; 1403 1404 // Timing 1405 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1406 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1407 1408 { 1409 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id()); 1410 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1411 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1412 1413 g1_policy()->record_full_collection_start(); 1414 1415 // Note: When we have a more flexible GC logging framework that 1416 // allows us to add optional attributes to a GC log record we 1417 // could consider timing and reporting how long we wait in the 1418 // following two methods. 1419 wait_while_free_regions_coming(); 1420 // If we start the compaction before the CM threads finish 1421 // scanning the root regions we might trip them over as we'll 1422 // be moving objects / updating references. So let's wait until 1423 // they are done. By telling them to abort, they should complete 1424 // early. 1425 _cm->root_regions()->abort(); 1426 _cm->root_regions()->wait_until_scan_finished(); 1427 append_secondary_free_list_if_not_empty_with_lock(); 1428 1429 gc_prologue(true); 1430 increment_total_collections(true /* full gc */); 1431 increment_old_marking_cycles_started(); 1432 1433 assert(used() == recalculate_used(), "Should be equal"); 1434 1435 verify_before_gc(); 1436 1437 check_bitmaps("Full GC Start"); 1438 pre_full_gc_dump(gc_timer); 1439 1440 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1441 1442 // Disable discovery and empty the discovered lists 1443 // for the CM ref processor. 1444 ref_processor_cm()->disable_discovery(); 1445 ref_processor_cm()->abandon_partial_discovery(); 1446 ref_processor_cm()->verify_no_references_recorded(); 1447 1448 // Abandon current iterations of concurrent marking and concurrent 1449 // refinement, if any are in progress. We have to do this before 1450 // wait_until_scan_finished() below. 1451 concurrent_mark()->abort(); 1452 1453 // Make sure we'll choose a new allocation region afterwards. 1454 _allocator->release_mutator_alloc_region(); 1455 _allocator->abandon_gc_alloc_regions(); 1456 g1_rem_set()->cleanupHRRS(); 1457 1458 // We should call this after we retire any currently active alloc 1459 // regions so that all the ALLOC / RETIRE events are generated 1460 // before the start GC event. 1461 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1462 1463 // We may have added regions to the current incremental collection 1464 // set between the last GC or pause and now. We need to clear the 1465 // incremental collection set and then start rebuilding it afresh 1466 // after this full GC. 1467 abandon_collection_set(g1_policy()->inc_cset_head()); 1468 g1_policy()->clear_incremental_cset(); 1469 g1_policy()->stop_incremental_cset_building(); 1470 1471 tear_down_region_sets(false /* free_list_only */); 1472 collector_state()->set_gcs_are_young(true); 1473 1474 // See the comments in g1CollectedHeap.hpp and 1475 // G1CollectedHeap::ref_processing_init() about 1476 // how reference processing currently works in G1. 1477 1478 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1479 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1480 1481 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1482 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1483 1484 ref_processor_stw()->enable_discovery(); 1485 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1486 1487 // Do collection work 1488 { 1489 HandleMark hm; // Discard invalid handles created during gc 1490 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1491 } 1492 1493 assert(num_free_regions() == 0, "we should not have added any free regions"); 1494 rebuild_region_sets(false /* free_list_only */); 1495 1496 // Enqueue any discovered reference objects that have 1497 // not been removed from the discovered lists. 1498 ref_processor_stw()->enqueue_discovered_references(); 1499 1500 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1501 1502 MemoryService::track_memory_usage(); 1503 1504 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1505 ref_processor_stw()->verify_no_references_recorded(); 1506 1507 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1508 ClassLoaderDataGraph::purge(); 1509 MetaspaceAux::verify_metrics(); 1510 1511 // Note: since we've just done a full GC, concurrent 1512 // marking is no longer active. Therefore we need not 1513 // re-enable reference discovery for the CM ref processor. 1514 // That will be done at the start of the next marking cycle. 1515 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1516 ref_processor_cm()->verify_no_references_recorded(); 1517 1518 reset_gc_time_stamp(); 1519 // Since everything potentially moved, we will clear all remembered 1520 // sets, and clear all cards. Later we will rebuild remembered 1521 // sets. We will also reset the GC time stamps of the regions. 1522 clear_rsets_post_compaction(); 1523 check_gc_time_stamps(); 1524 1525 // Resize the heap if necessary. 1526 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1527 1528 if (_hr_printer.is_active()) { 1529 // We should do this after we potentially resize the heap so 1530 // that all the COMMIT / UNCOMMIT events are generated before 1531 // the end GC event. 1532 1533 print_hrm_post_compaction(); 1534 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1535 } 1536 1537 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1538 if (hot_card_cache->use_cache()) { 1539 hot_card_cache->reset_card_counts(); 1540 hot_card_cache->reset_hot_cache(); 1541 } 1542 1543 // Rebuild remembered sets of all regions. 1544 uint n_workers = 1545 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1546 workers()->active_workers(), 1547 Threads::number_of_non_daemon_threads()); 1548 workers()->set_active_workers(n_workers); 1549 1550 ParRebuildRSTask rebuild_rs_task(this); 1551 workers()->run_task(&rebuild_rs_task); 1552 1553 // Rebuild the strong code root lists for each region 1554 rebuild_strong_code_roots(); 1555 1556 if (true) { // FIXME 1557 MetaspaceGC::compute_new_size(); 1558 } 1559 1560 #ifdef TRACESPINNING 1561 ParallelTaskTerminator::print_termination_counts(); 1562 #endif 1563 1564 // Discard all rset updates 1565 JavaThread::dirty_card_queue_set().abandon_logs(); 1566 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1567 1568 _young_list->reset_sampled_info(); 1569 // At this point there should be no regions in the 1570 // entire heap tagged as young. 1571 assert(check_young_list_empty(true /* check_heap */), 1572 "young list should be empty at this point"); 1573 1574 // Update the number of full collections that have been completed. 1575 increment_old_marking_cycles_completed(false /* concurrent */); 1576 1577 _hrm.verify_optional(); 1578 verify_region_sets_optional(); 1579 1580 verify_after_gc(); 1581 1582 // Clear the previous marking bitmap, if needed for bitmap verification. 1583 // Note we cannot do this when we clear the next marking bitmap in 1584 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1585 // objects marked during a full GC against the previous bitmap. 1586 // But we need to clear it before calling check_bitmaps below since 1587 // the full GC has compacted objects and updated TAMS but not updated 1588 // the prev bitmap. 1589 if (G1VerifyBitmaps) { 1590 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1591 } 1592 check_bitmaps("Full GC End"); 1593 1594 // Start a new incremental collection set for the next pause 1595 assert(g1_policy()->collection_set() == NULL, "must be"); 1596 g1_policy()->start_incremental_cset_building(); 1597 1598 clear_cset_fast_test(); 1599 1600 _allocator->init_mutator_alloc_region(); 1601 1602 g1_policy()->record_full_collection_end(); 1603 1604 if (G1Log::fine()) { 1605 g1_policy()->print_heap_transition(); 1606 } 1607 1608 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1609 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1610 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1611 // before any GC notifications are raised. 1612 g1mm()->update_sizes(); 1613 1614 gc_epilogue(true); 1615 } 1616 1617 if (G1Log::finer()) { 1618 g1_policy()->print_detailed_heap_transition(true /* full */); 1619 } 1620 1621 print_heap_after_gc(); 1622 trace_heap_after_gc(gc_tracer); 1623 1624 post_full_gc_dump(gc_timer); 1625 1626 gc_timer->register_gc_end(); 1627 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1628 } 1629 1630 return true; 1631 } 1632 1633 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1634 // do_collection() will return whether it succeeded in performing 1635 // the GC. Currently, there is no facility on the 1636 // do_full_collection() API to notify the caller than the collection 1637 // did not succeed (e.g., because it was locked out by the GC 1638 // locker). So, right now, we'll ignore the return value. 1639 bool dummy = do_collection(true, /* explicit_gc */ 1640 clear_all_soft_refs, 1641 0 /* word_size */); 1642 } 1643 1644 // This code is mostly copied from TenuredGeneration. 1645 void 1646 G1CollectedHeap:: 1647 resize_if_necessary_after_full_collection(size_t word_size) { 1648 // Include the current allocation, if any, and bytes that will be 1649 // pre-allocated to support collections, as "used". 1650 const size_t used_after_gc = used(); 1651 const size_t capacity_after_gc = capacity(); 1652 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1653 1654 // This is enforced in arguments.cpp. 1655 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1656 "otherwise the code below doesn't make sense"); 1657 1658 // We don't have floating point command-line arguments 1659 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1660 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1661 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1662 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1663 1664 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1665 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1666 1667 // We have to be careful here as these two calculations can overflow 1668 // 32-bit size_t's. 1669 double used_after_gc_d = (double) used_after_gc; 1670 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1671 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1672 1673 // Let's make sure that they are both under the max heap size, which 1674 // by default will make them fit into a size_t. 1675 double desired_capacity_upper_bound = (double) max_heap_size; 1676 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1677 desired_capacity_upper_bound); 1678 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1679 desired_capacity_upper_bound); 1680 1681 // We can now safely turn them into size_t's. 1682 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1683 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1684 1685 // This assert only makes sense here, before we adjust them 1686 // with respect to the min and max heap size. 1687 assert(minimum_desired_capacity <= maximum_desired_capacity, 1688 err_msg("minimum_desired_capacity = " SIZE_FORMAT ", " 1689 "maximum_desired_capacity = " SIZE_FORMAT, 1690 minimum_desired_capacity, maximum_desired_capacity)); 1691 1692 // Should not be greater than the heap max size. No need to adjust 1693 // it with respect to the heap min size as it's a lower bound (i.e., 1694 // we'll try to make the capacity larger than it, not smaller). 1695 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1696 // Should not be less than the heap min size. No need to adjust it 1697 // with respect to the heap max size as it's an upper bound (i.e., 1698 // we'll try to make the capacity smaller than it, not greater). 1699 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1700 1701 if (capacity_after_gc < minimum_desired_capacity) { 1702 // Don't expand unless it's significant 1703 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1704 ergo_verbose4(ErgoHeapSizing, 1705 "attempt heap expansion", 1706 ergo_format_reason("capacity lower than " 1707 "min desired capacity after Full GC") 1708 ergo_format_byte("capacity") 1709 ergo_format_byte("occupancy") 1710 ergo_format_byte_perc("min desired capacity"), 1711 capacity_after_gc, used_after_gc, 1712 minimum_desired_capacity, (double) MinHeapFreeRatio); 1713 expand(expand_bytes); 1714 1715 // No expansion, now see if we want to shrink 1716 } else if (capacity_after_gc > maximum_desired_capacity) { 1717 // Capacity too large, compute shrinking size 1718 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1719 ergo_verbose4(ErgoHeapSizing, 1720 "attempt heap shrinking", 1721 ergo_format_reason("capacity higher than " 1722 "max desired capacity after Full GC") 1723 ergo_format_byte("capacity") 1724 ergo_format_byte("occupancy") 1725 ergo_format_byte_perc("max desired capacity"), 1726 capacity_after_gc, used_after_gc, 1727 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1728 shrink(shrink_bytes); 1729 } 1730 } 1731 1732 1733 HeapWord* 1734 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1735 AllocationContext_t context, 1736 bool* succeeded) { 1737 assert_at_safepoint(true /* should_be_vm_thread */); 1738 1739 *succeeded = true; 1740 // Let's attempt the allocation first. 1741 HeapWord* result = 1742 attempt_allocation_at_safepoint(word_size, 1743 context, 1744 false /* expect_null_mutator_alloc_region */); 1745 if (result != NULL) { 1746 assert(*succeeded, "sanity"); 1747 return result; 1748 } 1749 1750 // In a G1 heap, we're supposed to keep allocation from failing by 1751 // incremental pauses. Therefore, at least for now, we'll favor 1752 // expansion over collection. (This might change in the future if we can 1753 // do something smarter than full collection to satisfy a failed alloc.) 1754 result = expand_and_allocate(word_size, context); 1755 if (result != NULL) { 1756 assert(*succeeded, "sanity"); 1757 return result; 1758 } 1759 1760 // Expansion didn't work, we'll try to do a Full GC. 1761 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1762 false, /* clear_all_soft_refs */ 1763 word_size); 1764 if (!gc_succeeded) { 1765 *succeeded = false; 1766 return NULL; 1767 } 1768 1769 // Retry the allocation 1770 result = attempt_allocation_at_safepoint(word_size, 1771 context, 1772 true /* expect_null_mutator_alloc_region */); 1773 if (result != NULL) { 1774 assert(*succeeded, "sanity"); 1775 return result; 1776 } 1777 1778 // Then, try a Full GC that will collect all soft references. 1779 gc_succeeded = do_collection(false, /* explicit_gc */ 1780 true, /* clear_all_soft_refs */ 1781 word_size); 1782 if (!gc_succeeded) { 1783 *succeeded = false; 1784 return NULL; 1785 } 1786 1787 // Retry the allocation once more 1788 result = attempt_allocation_at_safepoint(word_size, 1789 context, 1790 true /* expect_null_mutator_alloc_region */); 1791 if (result != NULL) { 1792 assert(*succeeded, "sanity"); 1793 return result; 1794 } 1795 1796 assert(!collector_policy()->should_clear_all_soft_refs(), 1797 "Flag should have been handled and cleared prior to this point"); 1798 1799 // What else? We might try synchronous finalization later. If the total 1800 // space available is large enough for the allocation, then a more 1801 // complete compaction phase than we've tried so far might be 1802 // appropriate. 1803 assert(*succeeded, "sanity"); 1804 return NULL; 1805 } 1806 1807 // Attempting to expand the heap sufficiently 1808 // to support an allocation of the given "word_size". If 1809 // successful, perform the allocation and return the address of the 1810 // allocated block, or else "NULL". 1811 1812 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1813 assert_at_safepoint(true /* should_be_vm_thread */); 1814 1815 verify_region_sets_optional(); 1816 1817 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1818 ergo_verbose1(ErgoHeapSizing, 1819 "attempt heap expansion", 1820 ergo_format_reason("allocation request failed") 1821 ergo_format_byte("allocation request"), 1822 word_size * HeapWordSize); 1823 if (expand(expand_bytes)) { 1824 _hrm.verify_optional(); 1825 verify_region_sets_optional(); 1826 return attempt_allocation_at_safepoint(word_size, 1827 context, 1828 false /* expect_null_mutator_alloc_region */); 1829 } 1830 return NULL; 1831 } 1832 1833 bool G1CollectedHeap::expand(size_t expand_bytes) { 1834 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1835 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1836 HeapRegion::GrainBytes); 1837 ergo_verbose2(ErgoHeapSizing, 1838 "expand the heap", 1839 ergo_format_byte("requested expansion amount") 1840 ergo_format_byte("attempted expansion amount"), 1841 expand_bytes, aligned_expand_bytes); 1842 1843 if (is_maximal_no_gc()) { 1844 ergo_verbose0(ErgoHeapSizing, 1845 "did not expand the heap", 1846 ergo_format_reason("heap already fully expanded")); 1847 return false; 1848 } 1849 1850 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1851 assert(regions_to_expand > 0, "Must expand by at least one region"); 1852 1853 uint expanded_by = _hrm.expand_by(regions_to_expand); 1854 1855 if (expanded_by > 0) { 1856 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1857 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1858 g1_policy()->record_new_heap_size(num_regions()); 1859 } else { 1860 ergo_verbose0(ErgoHeapSizing, 1861 "did not expand the heap", 1862 ergo_format_reason("heap expansion operation failed")); 1863 // The expansion of the virtual storage space was unsuccessful. 1864 // Let's see if it was because we ran out of swap. 1865 if (G1ExitOnExpansionFailure && 1866 _hrm.available() >= regions_to_expand) { 1867 // We had head room... 1868 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1869 } 1870 } 1871 return regions_to_expand > 0; 1872 } 1873 1874 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1875 size_t aligned_shrink_bytes = 1876 ReservedSpace::page_align_size_down(shrink_bytes); 1877 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1878 HeapRegion::GrainBytes); 1879 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1880 1881 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1882 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1883 1884 ergo_verbose3(ErgoHeapSizing, 1885 "shrink the heap", 1886 ergo_format_byte("requested shrinking amount") 1887 ergo_format_byte("aligned shrinking amount") 1888 ergo_format_byte("attempted shrinking amount"), 1889 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1890 if (num_regions_removed > 0) { 1891 g1_policy()->record_new_heap_size(num_regions()); 1892 } else { 1893 ergo_verbose0(ErgoHeapSizing, 1894 "did not shrink the heap", 1895 ergo_format_reason("heap shrinking operation failed")); 1896 } 1897 } 1898 1899 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1900 verify_region_sets_optional(); 1901 1902 // We should only reach here at the end of a Full GC which means we 1903 // should not not be holding to any GC alloc regions. The method 1904 // below will make sure of that and do any remaining clean up. 1905 _allocator->abandon_gc_alloc_regions(); 1906 1907 // Instead of tearing down / rebuilding the free lists here, we 1908 // could instead use the remove_all_pending() method on free_list to 1909 // remove only the ones that we need to remove. 1910 tear_down_region_sets(true /* free_list_only */); 1911 shrink_helper(shrink_bytes); 1912 rebuild_region_sets(true /* free_list_only */); 1913 1914 _hrm.verify_optional(); 1915 verify_region_sets_optional(); 1916 } 1917 1918 // Public methods. 1919 1920 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1921 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1922 #endif // _MSC_VER 1923 1924 1925 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1926 CollectedHeap(), 1927 _g1_policy(policy_), 1928 _dirty_card_queue_set(false), 1929 _into_cset_dirty_card_queue_set(false), 1930 _is_alive_closure_cm(this), 1931 _is_alive_closure_stw(this), 1932 _ref_processor_cm(NULL), 1933 _ref_processor_stw(NULL), 1934 _bot_shared(NULL), 1935 _cg1r(NULL), 1936 _g1mm(NULL), 1937 _refine_cte_cl(NULL), 1938 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1939 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1940 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1941 _humongous_reclaim_candidates(), 1942 _has_humongous_reclaim_candidates(false), 1943 _archive_allocator(NULL), 1944 _free_regions_coming(false), 1945 _young_list(new YoungList(this)), 1946 _gc_time_stamp(0), 1947 _summary_bytes_used(0), 1948 _survivor_evac_stats(YoungPLABSize, PLABWeight), 1949 _old_evac_stats(OldPLABSize, PLABWeight), 1950 _expand_heap_after_alloc_failure(true), 1951 _surviving_young_words(NULL), 1952 _old_marking_cycles_started(0), 1953 _old_marking_cycles_completed(0), 1954 _heap_summary_sent(false), 1955 _in_cset_fast_test(), 1956 _dirty_cards_region_list(NULL), 1957 _worker_cset_start_region(NULL), 1958 _worker_cset_start_region_time_stamp(NULL), 1959 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1960 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1961 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1962 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1963 1964 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads, 1965 /* are_GC_task_threads */true, 1966 /* are_ConcurrentGC_threads */false); 1967 _workers->initialize_workers(); 1968 1969 _allocator = G1Allocator::create_allocator(this); 1970 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1971 1972 // Override the default _filler_array_max_size so that no humongous filler 1973 // objects are created. 1974 _filler_array_max_size = _humongous_object_threshold_in_words; 1975 1976 uint n_queues = ParallelGCThreads; 1977 _task_queues = new RefToScanQueueSet(n_queues); 1978 1979 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1980 assert(n_rem_sets > 0, "Invariant."); 1981 1982 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1983 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC); 1984 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1985 1986 for (uint i = 0; i < n_queues; i++) { 1987 RefToScanQueue* q = new RefToScanQueue(); 1988 q->initialize(); 1989 _task_queues->register_queue(i, q); 1990 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1991 } 1992 clear_cset_start_regions(); 1993 1994 // Initialize the G1EvacuationFailureALot counters and flags. 1995 NOT_PRODUCT(reset_evacuation_should_fail();) 1996 1997 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1998 } 1999 2000 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 2001 size_t size, 2002 size_t translation_factor) { 2003 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 2004 // Allocate a new reserved space, preferring to use large pages. 2005 ReservedSpace rs(size, preferred_page_size); 2006 G1RegionToSpaceMapper* result = 2007 G1RegionToSpaceMapper::create_mapper(rs, 2008 size, 2009 rs.alignment(), 2010 HeapRegion::GrainBytes, 2011 translation_factor, 2012 mtGC); 2013 if (TracePageSizes) { 2014 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT, 2015 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size); 2016 } 2017 return result; 2018 } 2019 2020 jint G1CollectedHeap::initialize() { 2021 CollectedHeap::pre_initialize(); 2022 os::enable_vtime(); 2023 2024 G1Log::init(); 2025 2026 // Necessary to satisfy locking discipline assertions. 2027 2028 MutexLocker x(Heap_lock); 2029 2030 // We have to initialize the printer before committing the heap, as 2031 // it will be used then. 2032 _hr_printer.set_active(G1PrintHeapRegions); 2033 2034 // While there are no constraints in the GC code that HeapWordSize 2035 // be any particular value, there are multiple other areas in the 2036 // system which believe this to be true (e.g. oop->object_size in some 2037 // cases incorrectly returns the size in wordSize units rather than 2038 // HeapWordSize). 2039 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 2040 2041 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 2042 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 2043 size_t heap_alignment = collector_policy()->heap_alignment(); 2044 2045 // Ensure that the sizes are properly aligned. 2046 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2047 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2048 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 2049 2050 _refine_cte_cl = new RefineCardTableEntryClosure(); 2051 2052 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl); 2053 2054 // Reserve the maximum. 2055 2056 // When compressed oops are enabled, the preferred heap base 2057 // is calculated by subtracting the requested size from the 2058 // 32Gb boundary and using the result as the base address for 2059 // heap reservation. If the requested size is not aligned to 2060 // HeapRegion::GrainBytes (i.e. the alignment that is passed 2061 // into the ReservedHeapSpace constructor) then the actual 2062 // base of the reserved heap may end up differing from the 2063 // address that was requested (i.e. the preferred heap base). 2064 // If this happens then we could end up using a non-optimal 2065 // compressed oops mode. 2066 2067 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 2068 heap_alignment); 2069 2070 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 2071 2072 // Create the barrier set for the entire reserved region. 2073 G1SATBCardTableLoggingModRefBS* bs 2074 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 2075 bs->initialize(); 2076 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 2077 set_barrier_set(bs); 2078 2079 // Also create a G1 rem set. 2080 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 2081 2082 // Carve out the G1 part of the heap. 2083 2084 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 2085 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 2086 G1RegionToSpaceMapper* heap_storage = 2087 G1RegionToSpaceMapper::create_mapper(g1_rs, 2088 g1_rs.size(), 2089 page_size, 2090 HeapRegion::GrainBytes, 2091 1, 2092 mtJavaHeap); 2093 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(), 2094 max_byte_size, page_size, 2095 heap_rs.base(), 2096 heap_rs.size()); 2097 heap_storage->set_mapping_changed_listener(&_listener); 2098 2099 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 2100 G1RegionToSpaceMapper* bot_storage = 2101 create_aux_memory_mapper("Block offset table", 2102 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize), 2103 G1BlockOffsetSharedArray::heap_map_factor()); 2104 2105 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 2106 G1RegionToSpaceMapper* cardtable_storage = 2107 create_aux_memory_mapper("Card table", 2108 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize), 2109 G1SATBCardTableLoggingModRefBS::heap_map_factor()); 2110 2111 G1RegionToSpaceMapper* card_counts_storage = 2112 create_aux_memory_mapper("Card counts table", 2113 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 2114 G1CardCounts::heap_map_factor()); 2115 2116 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); 2117 G1RegionToSpaceMapper* prev_bitmap_storage = 2118 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor()); 2119 G1RegionToSpaceMapper* next_bitmap_storage = 2120 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor()); 2121 2122 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 2123 g1_barrier_set()->initialize(cardtable_storage); 2124 // Do later initialization work for concurrent refinement. 2125 _cg1r->init(card_counts_storage); 2126 2127 // 6843694 - ensure that the maximum region index can fit 2128 // in the remembered set structures. 2129 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2130 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2131 2132 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2133 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2134 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2135 "too many cards per region"); 2136 2137 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 2138 2139 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage); 2140 2141 { 2142 HeapWord* start = _hrm.reserved().start(); 2143 HeapWord* end = _hrm.reserved().end(); 2144 size_t granularity = HeapRegion::GrainBytes; 2145 2146 _in_cset_fast_test.initialize(start, end, granularity); 2147 _humongous_reclaim_candidates.initialize(start, end, granularity); 2148 } 2149 2150 // Create the ConcurrentMark data structure and thread. 2151 // (Must do this late, so that "max_regions" is defined.) 2152 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 2153 if (_cm == NULL || !_cm->completed_initialization()) { 2154 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 2155 return JNI_ENOMEM; 2156 } 2157 _cmThread = _cm->cmThread(); 2158 2159 // Initialize the from_card cache structure of HeapRegionRemSet. 2160 HeapRegionRemSet::init_heap(max_regions()); 2161 2162 // Now expand into the initial heap size. 2163 if (!expand(init_byte_size)) { 2164 vm_shutdown_during_initialization("Failed to allocate initial heap."); 2165 return JNI_ENOMEM; 2166 } 2167 2168 // Perform any initialization actions delegated to the policy. 2169 g1_policy()->init(); 2170 2171 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2172 SATB_Q_FL_lock, 2173 G1SATBProcessCompletedThreshold, 2174 Shared_SATB_Q_lock); 2175 2176 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 2177 DirtyCardQ_CBL_mon, 2178 DirtyCardQ_FL_lock, 2179 concurrent_g1_refine()->yellow_zone(), 2180 concurrent_g1_refine()->red_zone(), 2181 Shared_DirtyCardQ_lock); 2182 2183 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 2184 DirtyCardQ_CBL_mon, 2185 DirtyCardQ_FL_lock, 2186 -1, // never trigger processing 2187 -1, // no limit on length 2188 Shared_DirtyCardQ_lock, 2189 &JavaThread::dirty_card_queue_set()); 2190 2191 // Initialize the card queue set used to hold cards containing 2192 // references into the collection set. 2193 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 2194 DirtyCardQ_CBL_mon, 2195 DirtyCardQ_FL_lock, 2196 -1, // never trigger processing 2197 -1, // no limit on length 2198 Shared_DirtyCardQ_lock, 2199 &JavaThread::dirty_card_queue_set()); 2200 2201 // Here we allocate the dummy HeapRegion that is required by the 2202 // G1AllocRegion class. 2203 HeapRegion* dummy_region = _hrm.get_dummy_region(); 2204 2205 // We'll re-use the same region whether the alloc region will 2206 // require BOT updates or not and, if it doesn't, then a non-young 2207 // region will complain that it cannot support allocations without 2208 // BOT updates. So we'll tag the dummy region as eden to avoid that. 2209 dummy_region->set_eden(); 2210 // Make sure it's full. 2211 dummy_region->set_top(dummy_region->end()); 2212 G1AllocRegion::setup(this, dummy_region); 2213 2214 _allocator->init_mutator_alloc_region(); 2215 2216 // Do create of the monitoring and management support so that 2217 // values in the heap have been properly initialized. 2218 _g1mm = new G1MonitoringSupport(this); 2219 2220 G1StringDedup::initialize(); 2221 2222 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC); 2223 for (uint i = 0; i < ParallelGCThreads; i++) { 2224 new (&_preserved_objs[i]) OopAndMarkOopStack(); 2225 } 2226 2227 return JNI_OK; 2228 } 2229 2230 void G1CollectedHeap::stop() { 2231 // Stop all concurrent threads. We do this to make sure these threads 2232 // do not continue to execute and access resources (e.g. gclog_or_tty) 2233 // that are destroyed during shutdown. 2234 _cg1r->stop(); 2235 _cmThread->stop(); 2236 if (G1StringDedup::is_enabled()) { 2237 G1StringDedup::stop(); 2238 } 2239 } 2240 2241 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2242 return HeapRegion::max_region_size(); 2243 } 2244 2245 void G1CollectedHeap::post_initialize() { 2246 CollectedHeap::post_initialize(); 2247 ref_processing_init(); 2248 } 2249 2250 void G1CollectedHeap::ref_processing_init() { 2251 // Reference processing in G1 currently works as follows: 2252 // 2253 // * There are two reference processor instances. One is 2254 // used to record and process discovered references 2255 // during concurrent marking; the other is used to 2256 // record and process references during STW pauses 2257 // (both full and incremental). 2258 // * Both ref processors need to 'span' the entire heap as 2259 // the regions in the collection set may be dotted around. 2260 // 2261 // * For the concurrent marking ref processor: 2262 // * Reference discovery is enabled at initial marking. 2263 // * Reference discovery is disabled and the discovered 2264 // references processed etc during remarking. 2265 // * Reference discovery is MT (see below). 2266 // * Reference discovery requires a barrier (see below). 2267 // * Reference processing may or may not be MT 2268 // (depending on the value of ParallelRefProcEnabled 2269 // and ParallelGCThreads). 2270 // * A full GC disables reference discovery by the CM 2271 // ref processor and abandons any entries on it's 2272 // discovered lists. 2273 // 2274 // * For the STW processor: 2275 // * Non MT discovery is enabled at the start of a full GC. 2276 // * Processing and enqueueing during a full GC is non-MT. 2277 // * During a full GC, references are processed after marking. 2278 // 2279 // * Discovery (may or may not be MT) is enabled at the start 2280 // of an incremental evacuation pause. 2281 // * References are processed near the end of a STW evacuation pause. 2282 // * For both types of GC: 2283 // * Discovery is atomic - i.e. not concurrent. 2284 // * Reference discovery will not need a barrier. 2285 2286 MemRegion mr = reserved_region(); 2287 2288 // Concurrent Mark ref processor 2289 _ref_processor_cm = 2290 new ReferenceProcessor(mr, // span 2291 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2292 // mt processing 2293 ParallelGCThreads, 2294 // degree of mt processing 2295 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2296 // mt discovery 2297 MAX2(ParallelGCThreads, ConcGCThreads), 2298 // degree of mt discovery 2299 false, 2300 // Reference discovery is not atomic 2301 &_is_alive_closure_cm); 2302 // is alive closure 2303 // (for efficiency/performance) 2304 2305 // STW ref processor 2306 _ref_processor_stw = 2307 new ReferenceProcessor(mr, // span 2308 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2309 // mt processing 2310 ParallelGCThreads, 2311 // degree of mt processing 2312 (ParallelGCThreads > 1), 2313 // mt discovery 2314 ParallelGCThreads, 2315 // degree of mt discovery 2316 true, 2317 // Reference discovery is atomic 2318 &_is_alive_closure_stw); 2319 // is alive closure 2320 // (for efficiency/performance) 2321 } 2322 2323 size_t G1CollectedHeap::capacity() const { 2324 return _hrm.length() * HeapRegion::GrainBytes; 2325 } 2326 2327 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2328 assert(!hr->is_continues_humongous(), "pre-condition"); 2329 hr->reset_gc_time_stamp(); 2330 if (hr->is_starts_humongous()) { 2331 uint first_index = hr->hrm_index() + 1; 2332 uint last_index = hr->last_hc_index(); 2333 for (uint i = first_index; i < last_index; i += 1) { 2334 HeapRegion* chr = region_at(i); 2335 assert(chr->is_continues_humongous(), "sanity"); 2336 chr->reset_gc_time_stamp(); 2337 } 2338 } 2339 } 2340 2341 #ifndef PRODUCT 2342 2343 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2344 private: 2345 unsigned _gc_time_stamp; 2346 bool _failures; 2347 2348 public: 2349 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2350 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2351 2352 virtual bool doHeapRegion(HeapRegion* hr) { 2353 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2354 if (_gc_time_stamp != region_gc_time_stamp) { 2355 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, " 2356 "expected %d", HR_FORMAT_PARAMS(hr), 2357 region_gc_time_stamp, _gc_time_stamp); 2358 _failures = true; 2359 } 2360 return false; 2361 } 2362 2363 bool failures() { return _failures; } 2364 }; 2365 2366 void G1CollectedHeap::check_gc_time_stamps() { 2367 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2368 heap_region_iterate(&cl); 2369 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2370 } 2371 #endif // PRODUCT 2372 2373 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2374 DirtyCardQueue* into_cset_dcq, 2375 bool concurrent, 2376 uint worker_i) { 2377 // Clean cards in the hot card cache 2378 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2379 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2380 2381 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2382 size_t n_completed_buffers = 0; 2383 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2384 n_completed_buffers++; 2385 } 2386 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 2387 dcqs.clear_n_completed_buffers(); 2388 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2389 } 2390 2391 // Computes the sum of the storage used by the various regions. 2392 size_t G1CollectedHeap::used() const { 2393 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 2394 if (_archive_allocator != NULL) { 2395 result += _archive_allocator->used(); 2396 } 2397 return result; 2398 } 2399 2400 size_t G1CollectedHeap::used_unlocked() const { 2401 return _summary_bytes_used; 2402 } 2403 2404 class SumUsedClosure: public HeapRegionClosure { 2405 size_t _used; 2406 public: 2407 SumUsedClosure() : _used(0) {} 2408 bool doHeapRegion(HeapRegion* r) { 2409 if (!r->is_continues_humongous()) { 2410 _used += r->used(); 2411 } 2412 return false; 2413 } 2414 size_t result() { return _used; } 2415 }; 2416 2417 size_t G1CollectedHeap::recalculate_used() const { 2418 double recalculate_used_start = os::elapsedTime(); 2419 2420 SumUsedClosure blk; 2421 heap_region_iterate(&blk); 2422 2423 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2424 return blk.result(); 2425 } 2426 2427 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2428 switch (cause) { 2429 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2430 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2431 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 2432 case GCCause::_g1_humongous_allocation: return true; 2433 case GCCause::_update_allocation_context_stats_inc: return true; 2434 case GCCause::_wb_conc_mark: return true; 2435 default: return false; 2436 } 2437 } 2438 2439 #ifndef PRODUCT 2440 void G1CollectedHeap::allocate_dummy_regions() { 2441 // Let's fill up most of the region 2442 size_t word_size = HeapRegion::GrainWords - 1024; 2443 // And as a result the region we'll allocate will be humongous. 2444 guarantee(is_humongous(word_size), "sanity"); 2445 2446 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2447 // Let's use the existing mechanism for the allocation 2448 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2449 AllocationContext::system()); 2450 if (dummy_obj != NULL) { 2451 MemRegion mr(dummy_obj, word_size); 2452 CollectedHeap::fill_with_object(mr); 2453 } else { 2454 // If we can't allocate once, we probably cannot allocate 2455 // again. Let's get out of the loop. 2456 break; 2457 } 2458 } 2459 } 2460 #endif // !PRODUCT 2461 2462 void G1CollectedHeap::increment_old_marking_cycles_started() { 2463 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2464 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2465 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2466 _old_marking_cycles_started, _old_marking_cycles_completed)); 2467 2468 _old_marking_cycles_started++; 2469 } 2470 2471 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2472 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2473 2474 // We assume that if concurrent == true, then the caller is a 2475 // concurrent thread that was joined the Suspendible Thread 2476 // Set. If there's ever a cheap way to check this, we should add an 2477 // assert here. 2478 2479 // Given that this method is called at the end of a Full GC or of a 2480 // concurrent cycle, and those can be nested (i.e., a Full GC can 2481 // interrupt a concurrent cycle), the number of full collections 2482 // completed should be either one (in the case where there was no 2483 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2484 // behind the number of full collections started. 2485 2486 // This is the case for the inner caller, i.e. a Full GC. 2487 assert(concurrent || 2488 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2489 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2490 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2491 "is inconsistent with _old_marking_cycles_completed = %u", 2492 _old_marking_cycles_started, _old_marking_cycles_completed)); 2493 2494 // This is the case for the outer caller, i.e. the concurrent cycle. 2495 assert(!concurrent || 2496 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2497 err_msg("for outer caller (concurrent cycle): " 2498 "_old_marking_cycles_started = %u " 2499 "is inconsistent with _old_marking_cycles_completed = %u", 2500 _old_marking_cycles_started, _old_marking_cycles_completed)); 2501 2502 _old_marking_cycles_completed += 1; 2503 2504 // We need to clear the "in_progress" flag in the CM thread before 2505 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2506 // is set) so that if a waiter requests another System.gc() it doesn't 2507 // incorrectly see that a marking cycle is still in progress. 2508 if (concurrent) { 2509 _cmThread->set_idle(); 2510 } 2511 2512 // This notify_all() will ensure that a thread that called 2513 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2514 // and it's waiting for a full GC to finish will be woken up. It is 2515 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2516 FullGCCount_lock->notify_all(); 2517 } 2518 2519 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2520 collector_state()->set_concurrent_cycle_started(true); 2521 _gc_timer_cm->register_gc_start(start_time); 2522 2523 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2524 trace_heap_before_gc(_gc_tracer_cm); 2525 } 2526 2527 void G1CollectedHeap::register_concurrent_cycle_end() { 2528 if (collector_state()->concurrent_cycle_started()) { 2529 if (_cm->has_aborted()) { 2530 _gc_tracer_cm->report_concurrent_mode_failure(); 2531 } 2532 2533 _gc_timer_cm->register_gc_end(); 2534 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2535 2536 // Clear state variables to prepare for the next concurrent cycle. 2537 collector_state()->set_concurrent_cycle_started(false); 2538 _heap_summary_sent = false; 2539 } 2540 } 2541 2542 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2543 if (collector_state()->concurrent_cycle_started()) { 2544 // This function can be called when: 2545 // the cleanup pause is run 2546 // the concurrent cycle is aborted before the cleanup pause. 2547 // the concurrent cycle is aborted after the cleanup pause, 2548 // but before the concurrent cycle end has been registered. 2549 // Make sure that we only send the heap information once. 2550 if (!_heap_summary_sent) { 2551 trace_heap_after_gc(_gc_tracer_cm); 2552 _heap_summary_sent = true; 2553 } 2554 } 2555 } 2556 2557 void G1CollectedHeap::collect(GCCause::Cause cause) { 2558 assert_heap_not_locked(); 2559 2560 uint gc_count_before; 2561 uint old_marking_count_before; 2562 uint full_gc_count_before; 2563 bool retry_gc; 2564 2565 do { 2566 retry_gc = false; 2567 2568 { 2569 MutexLocker ml(Heap_lock); 2570 2571 // Read the GC count while holding the Heap_lock 2572 gc_count_before = total_collections(); 2573 full_gc_count_before = total_full_collections(); 2574 old_marking_count_before = _old_marking_cycles_started; 2575 } 2576 2577 if (should_do_concurrent_full_gc(cause)) { 2578 // Schedule an initial-mark evacuation pause that will start a 2579 // concurrent cycle. We're setting word_size to 0 which means that 2580 // we are not requesting a post-GC allocation. 2581 VM_G1IncCollectionPause op(gc_count_before, 2582 0, /* word_size */ 2583 true, /* should_initiate_conc_mark */ 2584 g1_policy()->max_pause_time_ms(), 2585 cause); 2586 op.set_allocation_context(AllocationContext::current()); 2587 2588 VMThread::execute(&op); 2589 if (!op.pause_succeeded()) { 2590 if (old_marking_count_before == _old_marking_cycles_started) { 2591 retry_gc = op.should_retry_gc(); 2592 } else { 2593 // A Full GC happened while we were trying to schedule the 2594 // initial-mark GC. No point in starting a new cycle given 2595 // that the whole heap was collected anyway. 2596 } 2597 2598 if (retry_gc) { 2599 if (GC_locker::is_active_and_needs_gc()) { 2600 GC_locker::stall_until_clear(); 2601 } 2602 } 2603 } 2604 } else { 2605 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2606 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2607 2608 // Schedule a standard evacuation pause. We're setting word_size 2609 // to 0 which means that we are not requesting a post-GC allocation. 2610 VM_G1IncCollectionPause op(gc_count_before, 2611 0, /* word_size */ 2612 false, /* should_initiate_conc_mark */ 2613 g1_policy()->max_pause_time_ms(), 2614 cause); 2615 VMThread::execute(&op); 2616 } else { 2617 // Schedule a Full GC. 2618 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2619 VMThread::execute(&op); 2620 } 2621 } 2622 } while (retry_gc); 2623 } 2624 2625 bool G1CollectedHeap::is_in(const void* p) const { 2626 if (_hrm.reserved().contains(p)) { 2627 // Given that we know that p is in the reserved space, 2628 // heap_region_containing_raw() should successfully 2629 // return the containing region. 2630 HeapRegion* hr = heap_region_containing_raw(p); 2631 return hr->is_in(p); 2632 } else { 2633 return false; 2634 } 2635 } 2636 2637 #ifdef ASSERT 2638 bool G1CollectedHeap::is_in_exact(const void* p) const { 2639 bool contains = reserved_region().contains(p); 2640 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2641 if (contains && available) { 2642 return true; 2643 } else { 2644 return false; 2645 } 2646 } 2647 #endif 2648 2649 bool G1CollectedHeap::obj_in_cs(oop obj) { 2650 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj); 2651 return r != NULL && r->in_collection_set(); 2652 } 2653 2654 // Iteration functions. 2655 2656 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2657 2658 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2659 ExtendedOopClosure* _cl; 2660 public: 2661 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2662 bool doHeapRegion(HeapRegion* r) { 2663 if (!r->is_continues_humongous()) { 2664 r->oop_iterate(_cl); 2665 } 2666 return false; 2667 } 2668 }; 2669 2670 // Iterates an ObjectClosure over all objects within a HeapRegion. 2671 2672 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2673 ObjectClosure* _cl; 2674 public: 2675 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2676 bool doHeapRegion(HeapRegion* r) { 2677 if (!r->is_continues_humongous()) { 2678 r->object_iterate(_cl); 2679 } 2680 return false; 2681 } 2682 }; 2683 2684 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2685 IterateObjectClosureRegionClosure blk(cl); 2686 heap_region_iterate(&blk); 2687 } 2688 2689 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2690 _hrm.iterate(cl); 2691 } 2692 2693 void 2694 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, 2695 uint worker_id, 2696 HeapRegionClaimer *hrclaimer, 2697 bool concurrent) const { 2698 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); 2699 } 2700 2701 // Clear the cached CSet starting regions and (more importantly) 2702 // the time stamps. Called when we reset the GC time stamp. 2703 void G1CollectedHeap::clear_cset_start_regions() { 2704 assert(_worker_cset_start_region != NULL, "sanity"); 2705 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2706 2707 for (uint i = 0; i < ParallelGCThreads; i++) { 2708 _worker_cset_start_region[i] = NULL; 2709 _worker_cset_start_region_time_stamp[i] = 0; 2710 } 2711 } 2712 2713 // Given the id of a worker, obtain or calculate a suitable 2714 // starting region for iterating over the current collection set. 2715 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2716 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2717 2718 HeapRegion* result = NULL; 2719 unsigned gc_time_stamp = get_gc_time_stamp(); 2720 2721 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2722 // Cached starting region for current worker was set 2723 // during the current pause - so it's valid. 2724 // Note: the cached starting heap region may be NULL 2725 // (when the collection set is empty). 2726 result = _worker_cset_start_region[worker_i]; 2727 assert(result == NULL || result->in_collection_set(), "sanity"); 2728 return result; 2729 } 2730 2731 // The cached entry was not valid so let's calculate 2732 // a suitable starting heap region for this worker. 2733 2734 // We want the parallel threads to start their collection 2735 // set iteration at different collection set regions to 2736 // avoid contention. 2737 // If we have: 2738 // n collection set regions 2739 // p threads 2740 // Then thread t will start at region floor ((t * n) / p) 2741 2742 result = g1_policy()->collection_set(); 2743 uint cs_size = g1_policy()->cset_region_length(); 2744 uint active_workers = workers()->active_workers(); 2745 2746 uint end_ind = (cs_size * worker_i) / active_workers; 2747 uint start_ind = 0; 2748 2749 if (worker_i > 0 && 2750 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2751 // Previous workers starting region is valid 2752 // so let's iterate from there 2753 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2754 result = _worker_cset_start_region[worker_i - 1]; 2755 } 2756 2757 for (uint i = start_ind; i < end_ind; i++) { 2758 result = result->next_in_collection_set(); 2759 } 2760 2761 // Note: the calculated starting heap region may be NULL 2762 // (when the collection set is empty). 2763 assert(result == NULL || result->in_collection_set(), "sanity"); 2764 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2765 "should be updated only once per pause"); 2766 _worker_cset_start_region[worker_i] = result; 2767 OrderAccess::storestore(); 2768 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2769 return result; 2770 } 2771 2772 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2773 HeapRegion* r = g1_policy()->collection_set(); 2774 while (r != NULL) { 2775 HeapRegion* next = r->next_in_collection_set(); 2776 if (cl->doHeapRegion(r)) { 2777 cl->incomplete(); 2778 return; 2779 } 2780 r = next; 2781 } 2782 } 2783 2784 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2785 HeapRegionClosure *cl) { 2786 if (r == NULL) { 2787 // The CSet is empty so there's nothing to do. 2788 return; 2789 } 2790 2791 assert(r->in_collection_set(), 2792 "Start region must be a member of the collection set."); 2793 HeapRegion* cur = r; 2794 while (cur != NULL) { 2795 HeapRegion* next = cur->next_in_collection_set(); 2796 if (cl->doHeapRegion(cur) && false) { 2797 cl->incomplete(); 2798 return; 2799 } 2800 cur = next; 2801 } 2802 cur = g1_policy()->collection_set(); 2803 while (cur != r) { 2804 HeapRegion* next = cur->next_in_collection_set(); 2805 if (cl->doHeapRegion(cur) && false) { 2806 cl->incomplete(); 2807 return; 2808 } 2809 cur = next; 2810 } 2811 } 2812 2813 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2814 HeapRegion* result = _hrm.next_region_in_heap(from); 2815 while (result != NULL && result->is_pinned()) { 2816 result = _hrm.next_region_in_heap(result); 2817 } 2818 return result; 2819 } 2820 2821 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2822 HeapRegion* hr = heap_region_containing(addr); 2823 return hr->block_start(addr); 2824 } 2825 2826 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2827 HeapRegion* hr = heap_region_containing(addr); 2828 return hr->block_size(addr); 2829 } 2830 2831 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2832 HeapRegion* hr = heap_region_containing(addr); 2833 return hr->block_is_obj(addr); 2834 } 2835 2836 bool G1CollectedHeap::supports_tlab_allocation() const { 2837 return true; 2838 } 2839 2840 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2841 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2842 } 2843 2844 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2845 return young_list()->eden_used_bytes(); 2846 } 2847 2848 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2849 // must be smaller than the humongous object limit. 2850 size_t G1CollectedHeap::max_tlab_size() const { 2851 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 2852 } 2853 2854 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2855 AllocationContext_t context = AllocationContext::current(); 2856 return _allocator->unsafe_max_tlab_alloc(context); 2857 } 2858 2859 size_t G1CollectedHeap::max_capacity() const { 2860 return _hrm.reserved().byte_size(); 2861 } 2862 2863 jlong G1CollectedHeap::millis_since_last_gc() { 2864 // assert(false, "NYI"); 2865 return 0; 2866 } 2867 2868 void G1CollectedHeap::prepare_for_verify() { 2869 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2870 ensure_parsability(false); 2871 } 2872 g1_rem_set()->prepare_for_verify(); 2873 } 2874 2875 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 2876 VerifyOption vo) { 2877 switch (vo) { 2878 case VerifyOption_G1UsePrevMarking: 2879 return hr->obj_allocated_since_prev_marking(obj); 2880 case VerifyOption_G1UseNextMarking: 2881 return hr->obj_allocated_since_next_marking(obj); 2882 case VerifyOption_G1UseMarkWord: 2883 return false; 2884 default: 2885 ShouldNotReachHere(); 2886 } 2887 return false; // keep some compilers happy 2888 } 2889 2890 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 2891 switch (vo) { 2892 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 2893 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 2894 case VerifyOption_G1UseMarkWord: return NULL; 2895 default: ShouldNotReachHere(); 2896 } 2897 return NULL; // keep some compilers happy 2898 } 2899 2900 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 2901 switch (vo) { 2902 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 2903 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 2904 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 2905 default: ShouldNotReachHere(); 2906 } 2907 return false; // keep some compilers happy 2908 } 2909 2910 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 2911 switch (vo) { 2912 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 2913 case VerifyOption_G1UseNextMarking: return "NTAMS"; 2914 case VerifyOption_G1UseMarkWord: return "NONE"; 2915 default: ShouldNotReachHere(); 2916 } 2917 return NULL; // keep some compilers happy 2918 } 2919 2920 class VerifyRootsClosure: public OopClosure { 2921 private: 2922 G1CollectedHeap* _g1h; 2923 VerifyOption _vo; 2924 bool _failures; 2925 public: 2926 // _vo == UsePrevMarking -> use "prev" marking information, 2927 // _vo == UseNextMarking -> use "next" marking information, 2928 // _vo == UseMarkWord -> use mark word from object header. 2929 VerifyRootsClosure(VerifyOption vo) : 2930 _g1h(G1CollectedHeap::heap()), 2931 _vo(vo), 2932 _failures(false) { } 2933 2934 bool failures() { return _failures; } 2935 2936 template <class T> void do_oop_nv(T* p) { 2937 T heap_oop = oopDesc::load_heap_oop(p); 2938 if (!oopDesc::is_null(heap_oop)) { 2939 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2940 if (_g1h->is_obj_dead_cond(obj, _vo)) { 2941 gclog_or_tty->print_cr("Root location " PTR_FORMAT " " 2942 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj)); 2943 if (_vo == VerifyOption_G1UseMarkWord) { 2944 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark()); 2945 } 2946 obj->print_on(gclog_or_tty); 2947 _failures = true; 2948 } 2949 } 2950 } 2951 2952 void do_oop(oop* p) { do_oop_nv(p); } 2953 void do_oop(narrowOop* p) { do_oop_nv(p); } 2954 }; 2955 2956 class G1VerifyCodeRootOopClosure: public OopClosure { 2957 G1CollectedHeap* _g1h; 2958 OopClosure* _root_cl; 2959 nmethod* _nm; 2960 VerifyOption _vo; 2961 bool _failures; 2962 2963 template <class T> void do_oop_work(T* p) { 2964 // First verify that this root is live 2965 _root_cl->do_oop(p); 2966 2967 if (!G1VerifyHeapRegionCodeRoots) { 2968 // We're not verifying the code roots attached to heap region. 2969 return; 2970 } 2971 2972 // Don't check the code roots during marking verification in a full GC 2973 if (_vo == VerifyOption_G1UseMarkWord) { 2974 return; 2975 } 2976 2977 // Now verify that the current nmethod (which contains p) is 2978 // in the code root list of the heap region containing the 2979 // object referenced by p. 2980 2981 T heap_oop = oopDesc::load_heap_oop(p); 2982 if (!oopDesc::is_null(heap_oop)) { 2983 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2984 2985 // Now fetch the region containing the object 2986 HeapRegion* hr = _g1h->heap_region_containing(obj); 2987 HeapRegionRemSet* hrrs = hr->rem_set(); 2988 // Verify that the strong code root list for this region 2989 // contains the nmethod 2990 if (!hrrs->strong_code_roots_list_contains(_nm)) { 2991 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " " 2992 "from nmethod " PTR_FORMAT " not in strong " 2993 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")", 2994 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end())); 2995 _failures = true; 2996 } 2997 } 2998 } 2999 3000 public: 3001 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 3002 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 3003 3004 void do_oop(oop* p) { do_oop_work(p); } 3005 void do_oop(narrowOop* p) { do_oop_work(p); } 3006 3007 void set_nmethod(nmethod* nm) { _nm = nm; } 3008 bool failures() { return _failures; } 3009 }; 3010 3011 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 3012 G1VerifyCodeRootOopClosure* _oop_cl; 3013 3014 public: 3015 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 3016 _oop_cl(oop_cl) {} 3017 3018 void do_code_blob(CodeBlob* cb) { 3019 nmethod* nm = cb->as_nmethod_or_null(); 3020 if (nm != NULL) { 3021 _oop_cl->set_nmethod(nm); 3022 nm->oops_do(_oop_cl); 3023 } 3024 } 3025 }; 3026 3027 class YoungRefCounterClosure : public OopClosure { 3028 G1CollectedHeap* _g1h; 3029 int _count; 3030 public: 3031 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 3032 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 3033 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 3034 3035 int count() { return _count; } 3036 void reset_count() { _count = 0; }; 3037 }; 3038 3039 class VerifyKlassClosure: public KlassClosure { 3040 YoungRefCounterClosure _young_ref_counter_closure; 3041 OopClosure *_oop_closure; 3042 public: 3043 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 3044 void do_klass(Klass* k) { 3045 k->oops_do(_oop_closure); 3046 3047 _young_ref_counter_closure.reset_count(); 3048 k->oops_do(&_young_ref_counter_closure); 3049 if (_young_ref_counter_closure.count() > 0) { 3050 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k))); 3051 } 3052 } 3053 }; 3054 3055 class VerifyLivenessOopClosure: public OopClosure { 3056 G1CollectedHeap* _g1h; 3057 VerifyOption _vo; 3058 public: 3059 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 3060 _g1h(g1h), _vo(vo) 3061 { } 3062 void do_oop(narrowOop *p) { do_oop_work(p); } 3063 void do_oop( oop *p) { do_oop_work(p); } 3064 3065 template <class T> void do_oop_work(T *p) { 3066 oop obj = oopDesc::load_decode_heap_oop(p); 3067 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 3068 "Dead object referenced by a not dead object"); 3069 } 3070 }; 3071 3072 class VerifyObjsInRegionClosure: public ObjectClosure { 3073 private: 3074 G1CollectedHeap* _g1h; 3075 size_t _live_bytes; 3076 HeapRegion *_hr; 3077 VerifyOption _vo; 3078 public: 3079 // _vo == UsePrevMarking -> use "prev" marking information, 3080 // _vo == UseNextMarking -> use "next" marking information, 3081 // _vo == UseMarkWord -> use mark word from object header. 3082 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 3083 : _live_bytes(0), _hr(hr), _vo(vo) { 3084 _g1h = G1CollectedHeap::heap(); 3085 } 3086 void do_object(oop o) { 3087 VerifyLivenessOopClosure isLive(_g1h, _vo); 3088 assert(o != NULL, "Huh?"); 3089 if (!_g1h->is_obj_dead_cond(o, _vo)) { 3090 // If the object is alive according to the mark word, 3091 // then verify that the marking information agrees. 3092 // Note we can't verify the contra-positive of the 3093 // above: if the object is dead (according to the mark 3094 // word), it may not be marked, or may have been marked 3095 // but has since became dead, or may have been allocated 3096 // since the last marking. 3097 if (_vo == VerifyOption_G1UseMarkWord) { 3098 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 3099 } 3100 3101 o->oop_iterate_no_header(&isLive); 3102 if (!_hr->obj_allocated_since_prev_marking(o)) { 3103 size_t obj_size = o->size(); // Make sure we don't overflow 3104 _live_bytes += (obj_size * HeapWordSize); 3105 } 3106 } 3107 } 3108 size_t live_bytes() { return _live_bytes; } 3109 }; 3110 3111 class VerifyArchiveOopClosure: public OopClosure { 3112 public: 3113 VerifyArchiveOopClosure(HeapRegion *hr) { } 3114 void do_oop(narrowOop *p) { do_oop_work(p); } 3115 void do_oop( oop *p) { do_oop_work(p); } 3116 3117 template <class T> void do_oop_work(T *p) { 3118 oop obj = oopDesc::load_decode_heap_oop(p); 3119 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj), 3120 err_msg("Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT, 3121 p2i(p), p2i(obj))); 3122 } 3123 }; 3124 3125 class VerifyArchiveRegionClosure: public ObjectClosure { 3126 public: 3127 VerifyArchiveRegionClosure(HeapRegion *hr) { } 3128 // Verify that all object pointers are to archive regions. 3129 void do_object(oop o) { 3130 VerifyArchiveOopClosure checkOop(NULL); 3131 assert(o != NULL, "Should not be here for NULL oops"); 3132 o->oop_iterate_no_header(&checkOop); 3133 } 3134 }; 3135 3136 class VerifyRegionClosure: public HeapRegionClosure { 3137 private: 3138 bool _par; 3139 VerifyOption _vo; 3140 bool _failures; 3141 public: 3142 // _vo == UsePrevMarking -> use "prev" marking information, 3143 // _vo == UseNextMarking -> use "next" marking information, 3144 // _vo == UseMarkWord -> use mark word from object header. 3145 VerifyRegionClosure(bool par, VerifyOption vo) 3146 : _par(par), 3147 _vo(vo), 3148 _failures(false) {} 3149 3150 bool failures() { 3151 return _failures; 3152 } 3153 3154 bool doHeapRegion(HeapRegion* r) { 3155 // For archive regions, verify there are no heap pointers to 3156 // non-pinned regions. For all others, verify liveness info. 3157 if (r->is_archive()) { 3158 VerifyArchiveRegionClosure verify_oop_pointers(r); 3159 r->object_iterate(&verify_oop_pointers); 3160 return true; 3161 } 3162 if (!r->is_continues_humongous()) { 3163 bool failures = false; 3164 r->verify(_vo, &failures); 3165 if (failures) { 3166 _failures = true; 3167 } else { 3168 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3169 r->object_iterate(¬_dead_yet_cl); 3170 if (_vo != VerifyOption_G1UseNextMarking) { 3171 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3172 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] " 3173 "max_live_bytes " SIZE_FORMAT " " 3174 "< calculated " SIZE_FORMAT, 3175 p2i(r->bottom()), p2i(r->end()), 3176 r->max_live_bytes(), 3177 not_dead_yet_cl.live_bytes()); 3178 _failures = true; 3179 } 3180 } else { 3181 // When vo == UseNextMarking we cannot currently do a sanity 3182 // check on the live bytes as the calculation has not been 3183 // finalized yet. 3184 } 3185 } 3186 } 3187 return false; // stop the region iteration if we hit a failure 3188 } 3189 }; 3190 3191 // This is the task used for parallel verification of the heap regions 3192 3193 class G1ParVerifyTask: public AbstractGangTask { 3194 private: 3195 G1CollectedHeap* _g1h; 3196 VerifyOption _vo; 3197 bool _failures; 3198 HeapRegionClaimer _hrclaimer; 3199 3200 public: 3201 // _vo == UsePrevMarking -> use "prev" marking information, 3202 // _vo == UseNextMarking -> use "next" marking information, 3203 // _vo == UseMarkWord -> use mark word from object header. 3204 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3205 AbstractGangTask("Parallel verify task"), 3206 _g1h(g1h), 3207 _vo(vo), 3208 _failures(false), 3209 _hrclaimer(g1h->workers()->active_workers()) {} 3210 3211 bool failures() { 3212 return _failures; 3213 } 3214 3215 void work(uint worker_id) { 3216 HandleMark hm; 3217 VerifyRegionClosure blk(true, _vo); 3218 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer); 3219 if (blk.failures()) { 3220 _failures = true; 3221 } 3222 } 3223 }; 3224 3225 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3226 if (SafepointSynchronize::is_at_safepoint()) { 3227 assert(Thread::current()->is_VM_thread(), 3228 "Expected to be executed serially by the VM thread at this point"); 3229 3230 if (!silent) { gclog_or_tty->print("Roots "); } 3231 VerifyRootsClosure rootsCl(vo); 3232 VerifyKlassClosure klassCl(this, &rootsCl); 3233 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3234 3235 // We apply the relevant closures to all the oops in the 3236 // system dictionary, class loader data graph, the string table 3237 // and the nmethods in the code cache. 3238 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3239 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3240 3241 { 3242 G1RootProcessor root_processor(this, 1); 3243 root_processor.process_all_roots(&rootsCl, 3244 &cldCl, 3245 &blobsCl); 3246 } 3247 3248 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3249 3250 if (vo != VerifyOption_G1UseMarkWord) { 3251 // If we're verifying during a full GC then the region sets 3252 // will have been torn down at the start of the GC. Therefore 3253 // verifying the region sets will fail. So we only verify 3254 // the region sets when not in a full GC. 3255 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3256 verify_region_sets(); 3257 } 3258 3259 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3260 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3261 3262 G1ParVerifyTask task(this, vo); 3263 workers()->run_task(&task); 3264 if (task.failures()) { 3265 failures = true; 3266 } 3267 3268 } else { 3269 VerifyRegionClosure blk(false, vo); 3270 heap_region_iterate(&blk); 3271 if (blk.failures()) { 3272 failures = true; 3273 } 3274 } 3275 3276 if (G1StringDedup::is_enabled()) { 3277 if (!silent) gclog_or_tty->print("StrDedup "); 3278 G1StringDedup::verify(); 3279 } 3280 3281 if (failures) { 3282 gclog_or_tty->print_cr("Heap:"); 3283 // It helps to have the per-region information in the output to 3284 // help us track down what went wrong. This is why we call 3285 // print_extended_on() instead of print_on(). 3286 print_extended_on(gclog_or_tty); 3287 gclog_or_tty->cr(); 3288 gclog_or_tty->flush(); 3289 } 3290 guarantee(!failures, "there should not have been any failures"); 3291 } else { 3292 if (!silent) { 3293 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3294 if (G1StringDedup::is_enabled()) { 3295 gclog_or_tty->print(", StrDedup"); 3296 } 3297 gclog_or_tty->print(") "); 3298 } 3299 } 3300 } 3301 3302 void G1CollectedHeap::verify(bool silent) { 3303 verify(silent, VerifyOption_G1UsePrevMarking); 3304 } 3305 3306 double G1CollectedHeap::verify(bool guard, const char* msg) { 3307 double verify_time_ms = 0.0; 3308 3309 if (guard && total_collections() >= VerifyGCStartAt) { 3310 double verify_start = os::elapsedTime(); 3311 HandleMark hm; // Discard invalid handles created during verification 3312 prepare_for_verify(); 3313 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3314 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3315 } 3316 3317 return verify_time_ms; 3318 } 3319 3320 void G1CollectedHeap::verify_before_gc() { 3321 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3322 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3323 } 3324 3325 void G1CollectedHeap::verify_after_gc() { 3326 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3327 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3328 } 3329 3330 class PrintRegionClosure: public HeapRegionClosure { 3331 outputStream* _st; 3332 public: 3333 PrintRegionClosure(outputStream* st) : _st(st) {} 3334 bool doHeapRegion(HeapRegion* r) { 3335 r->print_on(_st); 3336 return false; 3337 } 3338 }; 3339 3340 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3341 const HeapRegion* hr, 3342 const VerifyOption vo) const { 3343 switch (vo) { 3344 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3345 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3346 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive(); 3347 default: ShouldNotReachHere(); 3348 } 3349 return false; // keep some compilers happy 3350 } 3351 3352 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3353 const VerifyOption vo) const { 3354 switch (vo) { 3355 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3356 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3357 case VerifyOption_G1UseMarkWord: { 3358 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj); 3359 return !obj->is_gc_marked() && !hr->is_archive(); 3360 } 3361 default: ShouldNotReachHere(); 3362 } 3363 return false; // keep some compilers happy 3364 } 3365 3366 void G1CollectedHeap::print_on(outputStream* st) const { 3367 st->print(" %-20s", "garbage-first heap"); 3368 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3369 capacity()/K, used_unlocked()/K); 3370 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")", 3371 p2i(_hrm.reserved().start()), 3372 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords), 3373 p2i(_hrm.reserved().end())); 3374 st->cr(); 3375 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3376 uint young_regions = _young_list->length(); 3377 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3378 (size_t) young_regions * HeapRegion::GrainBytes / K); 3379 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3380 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3381 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3382 st->cr(); 3383 MetaspaceAux::print_on(st); 3384 } 3385 3386 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3387 print_on(st); 3388 3389 // Print the per-region information. 3390 st->cr(); 3391 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, " 3392 "HS=humongous(starts), HC=humongous(continues), " 3393 "CS=collection set, F=free, A=archive, TS=gc time stamp, " 3394 "PTAMS=previous top-at-mark-start, " 3395 "NTAMS=next top-at-mark-start)"); 3396 PrintRegionClosure blk(st); 3397 heap_region_iterate(&blk); 3398 } 3399 3400 void G1CollectedHeap::print_on_error(outputStream* st) const { 3401 this->CollectedHeap::print_on_error(st); 3402 3403 if (_cm != NULL) { 3404 st->cr(); 3405 _cm->print_on_error(st); 3406 } 3407 } 3408 3409 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3410 workers()->print_worker_threads_on(st); 3411 _cmThread->print_on(st); 3412 st->cr(); 3413 _cm->print_worker_threads_on(st); 3414 _cg1r->print_worker_threads_on(st); 3415 if (G1StringDedup::is_enabled()) { 3416 G1StringDedup::print_worker_threads_on(st); 3417 } 3418 } 3419 3420 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3421 workers()->threads_do(tc); 3422 tc->do_thread(_cmThread); 3423 _cg1r->threads_do(tc); 3424 if (G1StringDedup::is_enabled()) { 3425 G1StringDedup::threads_do(tc); 3426 } 3427 } 3428 3429 void G1CollectedHeap::print_tracing_info() const { 3430 // We'll overload this to mean "trace GC pause statistics." 3431 if (TraceYoungGenTime || TraceOldGenTime) { 3432 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3433 // to that. 3434 g1_policy()->print_tracing_info(); 3435 } 3436 if (G1SummarizeRSetStats) { 3437 g1_rem_set()->print_summary_info(); 3438 } 3439 if (G1SummarizeConcMark) { 3440 concurrent_mark()->print_summary_info(); 3441 } 3442 g1_policy()->print_yg_surv_rate_info(); 3443 } 3444 3445 #ifndef PRODUCT 3446 // Helpful for debugging RSet issues. 3447 3448 class PrintRSetsClosure : public HeapRegionClosure { 3449 private: 3450 const char* _msg; 3451 size_t _occupied_sum; 3452 3453 public: 3454 bool doHeapRegion(HeapRegion* r) { 3455 HeapRegionRemSet* hrrs = r->rem_set(); 3456 size_t occupied = hrrs->occupied(); 3457 _occupied_sum += occupied; 3458 3459 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT, 3460 HR_FORMAT_PARAMS(r)); 3461 if (occupied == 0) { 3462 gclog_or_tty->print_cr(" RSet is empty"); 3463 } else { 3464 hrrs->print(); 3465 } 3466 gclog_or_tty->print_cr("----------"); 3467 return false; 3468 } 3469 3470 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3471 gclog_or_tty->cr(); 3472 gclog_or_tty->print_cr("========================================"); 3473 gclog_or_tty->print_cr("%s", msg); 3474 gclog_or_tty->cr(); 3475 } 3476 3477 ~PrintRSetsClosure() { 3478 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 3479 gclog_or_tty->print_cr("========================================"); 3480 gclog_or_tty->cr(); 3481 } 3482 }; 3483 3484 void G1CollectedHeap::print_cset_rsets() { 3485 PrintRSetsClosure cl("Printing CSet RSets"); 3486 collection_set_iterate(&cl); 3487 } 3488 3489 void G1CollectedHeap::print_all_rsets() { 3490 PrintRSetsClosure cl("Printing All RSets");; 3491 heap_region_iterate(&cl); 3492 } 3493 #endif // PRODUCT 3494 3495 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 3496 YoungList* young_list = heap()->young_list(); 3497 3498 size_t eden_used_bytes = young_list->eden_used_bytes(); 3499 size_t survivor_used_bytes = young_list->survivor_used_bytes(); 3500 3501 size_t eden_capacity_bytes = 3502 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 3503 3504 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 3505 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes); 3506 } 3507 3508 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 3509 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 3510 gc_tracer->report_gc_heap_summary(when, heap_summary); 3511 3512 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 3513 gc_tracer->report_metaspace_summary(when, metaspace_summary); 3514 } 3515 3516 3517 G1CollectedHeap* G1CollectedHeap::heap() { 3518 CollectedHeap* heap = Universe::heap(); 3519 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 3520 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); 3521 return (G1CollectedHeap*)heap; 3522 } 3523 3524 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3525 // always_do_update_barrier = false; 3526 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3527 // Fill TLAB's and such 3528 accumulate_statistics_all_tlabs(); 3529 ensure_parsability(true); 3530 3531 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3532 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3533 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3534 } 3535 } 3536 3537 void G1CollectedHeap::gc_epilogue(bool full) { 3538 3539 if (G1SummarizeRSetStats && 3540 (G1SummarizeRSetStatsPeriod > 0) && 3541 // we are at the end of the GC. Total collections has already been increased. 3542 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3543 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3544 } 3545 3546 // FIXME: what is this about? 3547 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3548 // is set. 3549 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3550 "derived pointer present")); 3551 // always_do_update_barrier = true; 3552 3553 resize_all_tlabs(); 3554 allocation_context_stats().update(full); 3555 3556 // We have just completed a GC. Update the soft reference 3557 // policy with the new heap occupancy 3558 Universe::update_heap_info_at_gc(); 3559 } 3560 3561 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3562 uint gc_count_before, 3563 bool* succeeded, 3564 GCCause::Cause gc_cause) { 3565 assert_heap_not_locked_and_not_at_safepoint(); 3566 g1_policy()->record_stop_world_start(); 3567 VM_G1IncCollectionPause op(gc_count_before, 3568 word_size, 3569 false, /* should_initiate_conc_mark */ 3570 g1_policy()->max_pause_time_ms(), 3571 gc_cause); 3572 3573 op.set_allocation_context(AllocationContext::current()); 3574 VMThread::execute(&op); 3575 3576 HeapWord* result = op.result(); 3577 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3578 assert(result == NULL || ret_succeeded, 3579 "the result should be NULL if the VM did not succeed"); 3580 *succeeded = ret_succeeded; 3581 3582 assert_heap_not_locked(); 3583 return result; 3584 } 3585 3586 void 3587 G1CollectedHeap::doConcurrentMark() { 3588 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3589 if (!_cmThread->in_progress()) { 3590 _cmThread->set_started(); 3591 CGC_lock->notify(); 3592 } 3593 } 3594 3595 size_t G1CollectedHeap::pending_card_num() { 3596 size_t extra_cards = 0; 3597 JavaThread *curr = Threads::first(); 3598 while (curr != NULL) { 3599 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3600 extra_cards += dcq.size(); 3601 curr = curr->next(); 3602 } 3603 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3604 size_t buffer_size = dcqs.buffer_size(); 3605 size_t buffer_num = dcqs.completed_buffers_num(); 3606 3607 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3608 // in bytes - not the number of 'entries'. We need to convert 3609 // into a number of cards. 3610 return (buffer_size * buffer_num + extra_cards) / oopSize; 3611 } 3612 3613 size_t G1CollectedHeap::cards_scanned() { 3614 return g1_rem_set()->cardsScanned(); 3615 } 3616 3617 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3618 private: 3619 size_t _total_humongous; 3620 size_t _candidate_humongous; 3621 3622 DirtyCardQueue _dcq; 3623 3624 // We don't nominate objects with many remembered set entries, on 3625 // the assumption that such objects are likely still live. 3626 bool is_remset_small(HeapRegion* region) const { 3627 HeapRegionRemSet* const rset = region->rem_set(); 3628 return G1EagerReclaimHumongousObjectsWithStaleRefs 3629 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) 3630 : rset->is_empty(); 3631 } 3632 3633 bool is_typeArray_region(HeapRegion* region) const { 3634 return oop(region->bottom())->is_typeArray(); 3635 } 3636 3637 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { 3638 assert(region->is_starts_humongous(), "Must start a humongous object"); 3639 3640 // Candidate selection must satisfy the following constraints 3641 // while concurrent marking is in progress: 3642 // 3643 // * In order to maintain SATB invariants, an object must not be 3644 // reclaimed if it was allocated before the start of marking and 3645 // has not had its references scanned. Such an object must have 3646 // its references (including type metadata) scanned to ensure no 3647 // live objects are missed by the marking process. Objects 3648 // allocated after the start of concurrent marking don't need to 3649 // be scanned. 3650 // 3651 // * An object must not be reclaimed if it is on the concurrent 3652 // mark stack. Objects allocated after the start of concurrent 3653 // marking are never pushed on the mark stack. 3654 // 3655 // Nominating only objects allocated after the start of concurrent 3656 // marking is sufficient to meet both constraints. This may miss 3657 // some objects that satisfy the constraints, but the marking data 3658 // structures don't support efficiently performing the needed 3659 // additional tests or scrubbing of the mark stack. 3660 // 3661 // However, we presently only nominate is_typeArray() objects. 3662 // A humongous object containing references induces remembered 3663 // set entries on other regions. In order to reclaim such an 3664 // object, those remembered sets would need to be cleaned up. 3665 // 3666 // We also treat is_typeArray() objects specially, allowing them 3667 // to be reclaimed even if allocated before the start of 3668 // concurrent mark. For this we rely on mark stack insertion to 3669 // exclude is_typeArray() objects, preventing reclaiming an object 3670 // that is in the mark stack. We also rely on the metadata for 3671 // such objects to be built-in and so ensured to be kept live. 3672 // Frequent allocation and drop of large binary blobs is an 3673 // important use case for eager reclaim, and this special handling 3674 // may reduce needed headroom. 3675 3676 return is_typeArray_region(region) && is_remset_small(region); 3677 } 3678 3679 public: 3680 RegisterHumongousWithInCSetFastTestClosure() 3681 : _total_humongous(0), 3682 _candidate_humongous(0), 3683 _dcq(&JavaThread::dirty_card_queue_set()) { 3684 } 3685 3686 virtual bool doHeapRegion(HeapRegion* r) { 3687 if (!r->is_starts_humongous()) { 3688 return false; 3689 } 3690 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3691 3692 bool is_candidate = humongous_region_is_candidate(g1h, r); 3693 uint rindex = r->hrm_index(); 3694 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 3695 if (is_candidate) { 3696 _candidate_humongous++; 3697 g1h->register_humongous_region_with_cset(rindex); 3698 // Is_candidate already filters out humongous object with large remembered sets. 3699 // If we have a humongous object with a few remembered sets, we simply flush these 3700 // remembered set entries into the DCQS. That will result in automatic 3701 // re-evaluation of their remembered set entries during the following evacuation 3702 // phase. 3703 if (!r->rem_set()->is_empty()) { 3704 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 3705 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 3706 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 3707 HeapRegionRemSetIterator hrrs(r->rem_set()); 3708 size_t card_index; 3709 while (hrrs.has_next(card_index)) { 3710 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 3711 // The remembered set might contain references to already freed 3712 // regions. Filter out such entries to avoid failing card table 3713 // verification. 3714 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) { 3715 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 3716 *card_ptr = CardTableModRefBS::dirty_card_val(); 3717 _dcq.enqueue(card_ptr); 3718 } 3719 } 3720 } 3721 r->rem_set()->clear_locked(); 3722 } 3723 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 3724 } 3725 _total_humongous++; 3726 3727 return false; 3728 } 3729 3730 size_t total_humongous() const { return _total_humongous; } 3731 size_t candidate_humongous() const { return _candidate_humongous; } 3732 3733 void flush_rem_set_entries() { _dcq.flush(); } 3734 }; 3735 3736 void G1CollectedHeap::register_humongous_regions_with_cset() { 3737 if (!G1EagerReclaimHumongousObjects) { 3738 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 3739 return; 3740 } 3741 double time = os::elapsed_counter(); 3742 3743 // Collect reclaim candidate information and register candidates with cset. 3744 RegisterHumongousWithInCSetFastTestClosure cl; 3745 heap_region_iterate(&cl); 3746 3747 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 3748 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 3749 cl.total_humongous(), 3750 cl.candidate_humongous()); 3751 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3752 3753 // Finally flush all remembered set entries to re-check into the global DCQS. 3754 cl.flush_rem_set_entries(); 3755 } 3756 3757 void 3758 G1CollectedHeap::setup_surviving_young_words() { 3759 assert(_surviving_young_words == NULL, "pre-condition"); 3760 uint array_length = g1_policy()->young_cset_region_length(); 3761 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3762 if (_surviving_young_words == NULL) { 3763 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3764 "Not enough space for young surv words summary."); 3765 } 3766 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3767 #ifdef ASSERT 3768 for (uint i = 0; i < array_length; ++i) { 3769 assert( _surviving_young_words[i] == 0, "memset above" ); 3770 } 3771 #endif // !ASSERT 3772 } 3773 3774 void 3775 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3776 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3777 uint array_length = g1_policy()->young_cset_region_length(); 3778 for (uint i = 0; i < array_length; ++i) { 3779 _surviving_young_words[i] += surv_young_words[i]; 3780 } 3781 } 3782 3783 void 3784 G1CollectedHeap::cleanup_surviving_young_words() { 3785 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3786 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words); 3787 _surviving_young_words = NULL; 3788 } 3789 3790 #ifdef ASSERT 3791 class VerifyCSetClosure: public HeapRegionClosure { 3792 public: 3793 bool doHeapRegion(HeapRegion* hr) { 3794 // Here we check that the CSet region's RSet is ready for parallel 3795 // iteration. The fields that we'll verify are only manipulated 3796 // when the region is part of a CSet and is collected. Afterwards, 3797 // we reset these fields when we clear the region's RSet (when the 3798 // region is freed) so they are ready when the region is 3799 // re-allocated. The only exception to this is if there's an 3800 // evacuation failure and instead of freeing the region we leave 3801 // it in the heap. In that case, we reset these fields during 3802 // evacuation failure handling. 3803 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3804 3805 // Here's a good place to add any other checks we'd like to 3806 // perform on CSet regions. 3807 return false; 3808 } 3809 }; 3810 #endif // ASSERT 3811 3812 uint G1CollectedHeap::num_task_queues() const { 3813 return _task_queues->size(); 3814 } 3815 3816 #if TASKQUEUE_STATS 3817 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3818 st->print_raw_cr("GC Task Stats"); 3819 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3820 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3821 } 3822 3823 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3824 print_taskqueue_stats_hdr(st); 3825 3826 TaskQueueStats totals; 3827 const uint n = num_task_queues(); 3828 for (uint i = 0; i < n; ++i) { 3829 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 3830 totals += task_queue(i)->stats; 3831 } 3832 st->print_raw("tot "); totals.print(st); st->cr(); 3833 3834 DEBUG_ONLY(totals.verify()); 3835 } 3836 3837 void G1CollectedHeap::reset_taskqueue_stats() { 3838 const uint n = num_task_queues(); 3839 for (uint i = 0; i < n; ++i) { 3840 task_queue(i)->stats.reset(); 3841 } 3842 } 3843 #endif // TASKQUEUE_STATS 3844 3845 void G1CollectedHeap::log_gc_header() { 3846 if (!G1Log::fine()) { 3847 return; 3848 } 3849 3850 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id()); 3851 3852 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3853 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)") 3854 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3855 3856 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3857 } 3858 3859 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3860 if (!G1Log::fine()) { 3861 return; 3862 } 3863 3864 if (G1Log::finer()) { 3865 if (evacuation_failed()) { 3866 gclog_or_tty->print(" (to-space exhausted)"); 3867 } 3868 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3869 g1_policy()->phase_times()->note_gc_end(); 3870 g1_policy()->phase_times()->print(pause_time_sec); 3871 g1_policy()->print_detailed_heap_transition(); 3872 } else { 3873 if (evacuation_failed()) { 3874 gclog_or_tty->print("--"); 3875 } 3876 g1_policy()->print_heap_transition(); 3877 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3878 } 3879 gclog_or_tty->flush(); 3880 } 3881 3882 void G1CollectedHeap::wait_for_root_region_scanning() { 3883 double scan_wait_start = os::elapsedTime(); 3884 // We have to wait until the CM threads finish scanning the 3885 // root regions as it's the only way to ensure that all the 3886 // objects on them have been correctly scanned before we start 3887 // moving them during the GC. 3888 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3889 double wait_time_ms = 0.0; 3890 if (waited) { 3891 double scan_wait_end = os::elapsedTime(); 3892 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3893 } 3894 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3895 } 3896 3897 bool 3898 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3899 assert_at_safepoint(true /* should_be_vm_thread */); 3900 guarantee(!is_gc_active(), "collection is not reentrant"); 3901 3902 if (GC_locker::check_active_before_gc()) { 3903 return false; 3904 } 3905 3906 _gc_timer_stw->register_gc_start(); 3907 3908 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3909 3910 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3911 ResourceMark rm; 3912 3913 wait_for_root_region_scanning(); 3914 3915 G1Log::update_level(); 3916 print_heap_before_gc(); 3917 trace_heap_before_gc(_gc_tracer_stw); 3918 3919 verify_region_sets_optional(); 3920 verify_dirty_young_regions(); 3921 3922 // This call will decide whether this pause is an initial-mark 3923 // pause. If it is, during_initial_mark_pause() will return true 3924 // for the duration of this pause. 3925 g1_policy()->decide_on_conc_mark_initiation(); 3926 3927 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3928 assert(!collector_state()->during_initial_mark_pause() || 3929 collector_state()->gcs_are_young(), "sanity"); 3930 3931 // We also do not allow mixed GCs during marking. 3932 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity"); 3933 3934 // Record whether this pause is an initial mark. When the current 3935 // thread has completed its logging output and it's safe to signal 3936 // the CM thread, the flag's value in the policy has been reset. 3937 bool should_start_conc_mark = collector_state()->during_initial_mark_pause(); 3938 3939 // Inner scope for scope based logging, timers, and stats collection 3940 { 3941 EvacuationInfo evacuation_info; 3942 3943 if (collector_state()->during_initial_mark_pause()) { 3944 // We are about to start a marking cycle, so we increment the 3945 // full collection counter. 3946 increment_old_marking_cycles_started(); 3947 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3948 } 3949 3950 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 3951 3952 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3953 3954 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 3955 workers()->active_workers(), 3956 Threads::number_of_non_daemon_threads()); 3957 workers()->set_active_workers(active_workers); 3958 3959 double pause_start_sec = os::elapsedTime(); 3960 g1_policy()->phase_times()->note_gc_start(active_workers, collector_state()->mark_in_progress()); 3961 log_gc_header(); 3962 3963 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3964 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3965 3966 // If the secondary_free_list is not empty, append it to the 3967 // free_list. No need to wait for the cleanup operation to finish; 3968 // the region allocation code will check the secondary_free_list 3969 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3970 // set, skip this step so that the region allocation code has to 3971 // get entries from the secondary_free_list. 3972 if (!G1StressConcRegionFreeing) { 3973 append_secondary_free_list_if_not_empty_with_lock(); 3974 } 3975 3976 assert(check_young_list_well_formed(), "young list should be well formed"); 3977 3978 // Don't dynamically change the number of GC threads this early. A value of 3979 // 0 is used to indicate serial work. When parallel work is done, 3980 // it will be set. 3981 3982 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3983 IsGCActiveMark x; 3984 3985 gc_prologue(false); 3986 increment_total_collections(false /* full gc */); 3987 increment_gc_time_stamp(); 3988 3989 verify_before_gc(); 3990 3991 check_bitmaps("GC Start"); 3992 3993 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3994 3995 // Please see comment in g1CollectedHeap.hpp and 3996 // G1CollectedHeap::ref_processing_init() to see how 3997 // reference processing currently works in G1. 3998 3999 // Enable discovery in the STW reference processor 4000 ref_processor_stw()->enable_discovery(); 4001 4002 { 4003 // We want to temporarily turn off discovery by the 4004 // CM ref processor, if necessary, and turn it back on 4005 // on again later if we do. Using a scoped 4006 // NoRefDiscovery object will do this. 4007 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 4008 4009 // Forget the current alloc region (we might even choose it to be part 4010 // of the collection set!). 4011 _allocator->release_mutator_alloc_region(); 4012 4013 // We should call this after we retire the mutator alloc 4014 // region(s) so that all the ALLOC / RETIRE events are generated 4015 // before the start GC event. 4016 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 4017 4018 // This timing is only used by the ergonomics to handle our pause target. 4019 // It is unclear why this should not include the full pause. We will 4020 // investigate this in CR 7178365. 4021 // 4022 // Preserving the old comment here if that helps the investigation: 4023 // 4024 // The elapsed time induced by the start time below deliberately elides 4025 // the possible verification above. 4026 double sample_start_time_sec = os::elapsedTime(); 4027 4028 #if YOUNG_LIST_VERBOSE 4029 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 4030 _young_list->print(); 4031 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4032 #endif // YOUNG_LIST_VERBOSE 4033 4034 g1_policy()->record_collection_pause_start(sample_start_time_sec); 4035 4036 #if YOUNG_LIST_VERBOSE 4037 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 4038 _young_list->print(); 4039 #endif // YOUNG_LIST_VERBOSE 4040 4041 if (collector_state()->during_initial_mark_pause()) { 4042 concurrent_mark()->checkpointRootsInitialPre(); 4043 } 4044 4045 #if YOUNG_LIST_VERBOSE 4046 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 4047 _young_list->print(); 4048 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4049 #endif // YOUNG_LIST_VERBOSE 4050 4051 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 4052 4053 register_humongous_regions_with_cset(); 4054 4055 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table."); 4056 4057 _cm->note_start_of_gc(); 4058 // We call this after finalize_cset() to 4059 // ensure that the CSet has been finalized. 4060 _cm->verify_no_cset_oops(); 4061 4062 if (_hr_printer.is_active()) { 4063 HeapRegion* hr = g1_policy()->collection_set(); 4064 while (hr != NULL) { 4065 _hr_printer.cset(hr); 4066 hr = hr->next_in_collection_set(); 4067 } 4068 } 4069 4070 #ifdef ASSERT 4071 VerifyCSetClosure cl; 4072 collection_set_iterate(&cl); 4073 #endif // ASSERT 4074 4075 setup_surviving_young_words(); 4076 4077 // Initialize the GC alloc regions. 4078 _allocator->init_gc_alloc_regions(evacuation_info); 4079 4080 // Actually do the work... 4081 evacuate_collection_set(evacuation_info); 4082 4083 free_collection_set(g1_policy()->collection_set(), evacuation_info); 4084 4085 eagerly_reclaim_humongous_regions(); 4086 4087 g1_policy()->clear_collection_set(); 4088 4089 cleanup_surviving_young_words(); 4090 4091 // Start a new incremental collection set for the next pause. 4092 g1_policy()->start_incremental_cset_building(); 4093 4094 clear_cset_fast_test(); 4095 4096 _young_list->reset_sampled_info(); 4097 4098 // Don't check the whole heap at this point as the 4099 // GC alloc regions from this pause have been tagged 4100 // as survivors and moved on to the survivor list. 4101 // Survivor regions will fail the !is_young() check. 4102 assert(check_young_list_empty(false /* check_heap */), 4103 "young list should be empty"); 4104 4105 #if YOUNG_LIST_VERBOSE 4106 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 4107 _young_list->print(); 4108 #endif // YOUNG_LIST_VERBOSE 4109 4110 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 4111 _young_list->first_survivor_region(), 4112 _young_list->last_survivor_region()); 4113 4114 _young_list->reset_auxilary_lists(); 4115 4116 if (evacuation_failed()) { 4117 set_used(recalculate_used()); 4118 if (_archive_allocator != NULL) { 4119 _archive_allocator->clear_used(); 4120 } 4121 for (uint i = 0; i < ParallelGCThreads; i++) { 4122 if (_evacuation_failed_info_array[i].has_failed()) { 4123 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 4124 } 4125 } 4126 } else { 4127 // The "used" of the the collection set have already been subtracted 4128 // when they were freed. Add in the bytes evacuated. 4129 increase_used(g1_policy()->bytes_copied_during_gc()); 4130 } 4131 4132 if (collector_state()->during_initial_mark_pause()) { 4133 // We have to do this before we notify the CM threads that 4134 // they can start working to make sure that all the 4135 // appropriate initialization is done on the CM object. 4136 concurrent_mark()->checkpointRootsInitialPost(); 4137 collector_state()->set_mark_in_progress(true); 4138 // Note that we don't actually trigger the CM thread at 4139 // this point. We do that later when we're sure that 4140 // the current thread has completed its logging output. 4141 } 4142 4143 allocate_dummy_regions(); 4144 4145 #if YOUNG_LIST_VERBOSE 4146 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 4147 _young_list->print(); 4148 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4149 #endif // YOUNG_LIST_VERBOSE 4150 4151 _allocator->init_mutator_alloc_region(); 4152 4153 { 4154 size_t expand_bytes = g1_policy()->expansion_amount(); 4155 if (expand_bytes > 0) { 4156 size_t bytes_before = capacity(); 4157 // No need for an ergo verbose message here, 4158 // expansion_amount() does this when it returns a value > 0. 4159 if (!expand(expand_bytes)) { 4160 // We failed to expand the heap. Cannot do anything about it. 4161 } 4162 } 4163 } 4164 4165 // We redo the verification but now wrt to the new CSet which 4166 // has just got initialized after the previous CSet was freed. 4167 _cm->verify_no_cset_oops(); 4168 _cm->note_end_of_gc(); 4169 4170 // This timing is only used by the ergonomics to handle our pause target. 4171 // It is unclear why this should not include the full pause. We will 4172 // investigate this in CR 7178365. 4173 double sample_end_time_sec = os::elapsedTime(); 4174 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 4175 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 4176 4177 MemoryService::track_memory_usage(); 4178 4179 // In prepare_for_verify() below we'll need to scan the deferred 4180 // update buffers to bring the RSets up-to-date if 4181 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4182 // the update buffers we'll probably need to scan cards on the 4183 // regions we just allocated to (i.e., the GC alloc 4184 // regions). However, during the last GC we called 4185 // set_saved_mark() on all the GC alloc regions, so card 4186 // scanning might skip the [saved_mark_word()...top()] area of 4187 // those regions (i.e., the area we allocated objects into 4188 // during the last GC). But it shouldn't. Given that 4189 // saved_mark_word() is conditional on whether the GC time stamp 4190 // on the region is current or not, by incrementing the GC time 4191 // stamp here we invalidate all the GC time stamps on all the 4192 // regions and saved_mark_word() will simply return top() for 4193 // all the regions. This is a nicer way of ensuring this rather 4194 // than iterating over the regions and fixing them. In fact, the 4195 // GC time stamp increment here also ensures that 4196 // saved_mark_word() will return top() between pauses, i.e., 4197 // during concurrent refinement. So we don't need the 4198 // is_gc_active() check to decided which top to use when 4199 // scanning cards (see CR 7039627). 4200 increment_gc_time_stamp(); 4201 4202 verify_after_gc(); 4203 check_bitmaps("GC End"); 4204 4205 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4206 ref_processor_stw()->verify_no_references_recorded(); 4207 4208 // CM reference discovery will be re-enabled if necessary. 4209 } 4210 4211 // We should do this after we potentially expand the heap so 4212 // that all the COMMIT events are generated before the end GC 4213 // event, and after we retire the GC alloc regions so that all 4214 // RETIRE events are generated before the end GC event. 4215 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4216 4217 #ifdef TRACESPINNING 4218 ParallelTaskTerminator::print_termination_counts(); 4219 #endif 4220 4221 gc_epilogue(false); 4222 } 4223 4224 // Print the remainder of the GC log output. 4225 log_gc_footer(os::elapsedTime() - pause_start_sec); 4226 4227 // It is not yet to safe to tell the concurrent mark to 4228 // start as we have some optional output below. We don't want the 4229 // output from the concurrent mark thread interfering with this 4230 // logging output either. 4231 4232 _hrm.verify_optional(); 4233 verify_region_sets_optional(); 4234 4235 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats()); 4236 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4237 4238 print_heap_after_gc(); 4239 trace_heap_after_gc(_gc_tracer_stw); 4240 4241 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4242 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4243 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4244 // before any GC notifications are raised. 4245 g1mm()->update_sizes(); 4246 4247 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4248 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4249 _gc_timer_stw->register_gc_end(); 4250 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4251 } 4252 // It should now be safe to tell the concurrent mark thread to start 4253 // without its logging output interfering with the logging output 4254 // that came from the pause. 4255 4256 if (should_start_conc_mark) { 4257 // CAUTION: after the doConcurrentMark() call below, 4258 // the concurrent marking thread(s) could be running 4259 // concurrently with us. Make sure that anything after 4260 // this point does not assume that we are the only GC thread 4261 // running. Note: of course, the actual marking work will 4262 // not start until the safepoint itself is released in 4263 // SuspendibleThreadSet::desynchronize(). 4264 doConcurrentMark(); 4265 } 4266 4267 return true; 4268 } 4269 4270 void G1CollectedHeap::remove_self_forwarding_pointers() { 4271 double remove_self_forwards_start = os::elapsedTime(); 4272 4273 G1ParRemoveSelfForwardPtrsTask rsfp_task; 4274 workers()->run_task(&rsfp_task); 4275 4276 // Now restore saved marks, if any. 4277 for (uint i = 0; i < ParallelGCThreads; i++) { 4278 OopAndMarkOopStack& cur = _preserved_objs[i]; 4279 while (!cur.is_empty()) { 4280 OopAndMarkOop elem = cur.pop(); 4281 elem.set_mark(); 4282 } 4283 cur.clear(true); 4284 } 4285 4286 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4287 } 4288 4289 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 4290 if (!_evacuation_failed) { 4291 _evacuation_failed = true; 4292 } 4293 4294 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 4295 4296 // We want to call the "for_promotion_failure" version only in the 4297 // case of a promotion failure. 4298 if (m->must_be_preserved_for_promotion_failure(obj)) { 4299 OopAndMarkOop elem(obj, m); 4300 _preserved_objs[worker_id].push(elem); 4301 } 4302 } 4303 4304 void G1ParCopyHelper::mark_object(oop obj) { 4305 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); 4306 4307 // We know that the object is not moving so it's safe to read its size. 4308 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4309 } 4310 4311 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4312 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4313 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4314 assert(from_obj != to_obj, "should not be self-forwarded"); 4315 4316 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); 4317 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); 4318 4319 // The object might be in the process of being copied by another 4320 // worker so we cannot trust that its to-space image is 4321 // well-formed. So we have to read its size from its from-space 4322 // image which we know should not be changing. 4323 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4324 } 4325 4326 template <class T> 4327 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4328 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4329 _scanned_klass->record_modified_oops(); 4330 } 4331 } 4332 4333 template <G1Barrier barrier, G1Mark do_mark_object> 4334 template <class T> 4335 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4336 T heap_oop = oopDesc::load_heap_oop(p); 4337 4338 if (oopDesc::is_null(heap_oop)) { 4339 return; 4340 } 4341 4342 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4343 4344 assert(_worker_id == _par_scan_state->worker_id(), "sanity"); 4345 4346 const InCSetState state = _g1->in_cset_state(obj); 4347 if (state.is_in_cset()) { 4348 oop forwardee; 4349 markOop m = obj->mark(); 4350 if (m->is_marked()) { 4351 forwardee = (oop) m->decode_pointer(); 4352 } else { 4353 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m); 4354 } 4355 assert(forwardee != NULL, "forwardee should not be NULL"); 4356 oopDesc::encode_store_heap_oop(p, forwardee); 4357 if (do_mark_object != G1MarkNone && forwardee != obj) { 4358 // If the object is self-forwarded we don't need to explicitly 4359 // mark it, the evacuation failure protocol will do so. 4360 mark_forwarded_object(obj, forwardee); 4361 } 4362 4363 if (barrier == G1BarrierKlass) { 4364 do_klass_barrier(p, forwardee); 4365 } 4366 } else { 4367 if (state.is_humongous()) { 4368 _g1->set_humongous_is_live(obj); 4369 } 4370 // The object is not in collection set. If we're a root scanning 4371 // closure during an initial mark pause then attempt to mark the object. 4372 if (do_mark_object == G1MarkFromRoot) { 4373 mark_object(obj); 4374 } 4375 } 4376 } 4377 4378 class G1ParEvacuateFollowersClosure : public VoidClosure { 4379 protected: 4380 G1CollectedHeap* _g1h; 4381 G1ParScanThreadState* _par_scan_state; 4382 RefToScanQueueSet* _queues; 4383 ParallelTaskTerminator* _terminator; 4384 4385 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4386 RefToScanQueueSet* queues() { return _queues; } 4387 ParallelTaskTerminator* terminator() { return _terminator; } 4388 4389 public: 4390 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4391 G1ParScanThreadState* par_scan_state, 4392 RefToScanQueueSet* queues, 4393 ParallelTaskTerminator* terminator) 4394 : _g1h(g1h), _par_scan_state(par_scan_state), 4395 _queues(queues), _terminator(terminator) {} 4396 4397 void do_void(); 4398 4399 private: 4400 inline bool offer_termination(); 4401 }; 4402 4403 bool G1ParEvacuateFollowersClosure::offer_termination() { 4404 G1ParScanThreadState* const pss = par_scan_state(); 4405 pss->start_term_time(); 4406 const bool res = terminator()->offer_termination(); 4407 pss->end_term_time(); 4408 return res; 4409 } 4410 4411 void G1ParEvacuateFollowersClosure::do_void() { 4412 G1ParScanThreadState* const pss = par_scan_state(); 4413 pss->trim_queue(); 4414 do { 4415 pss->steal_and_trim_queue(queues()); 4416 } while (!offer_termination()); 4417 } 4418 4419 class G1KlassScanClosure : public KlassClosure { 4420 G1ParCopyHelper* _closure; 4421 bool _process_only_dirty; 4422 int _count; 4423 public: 4424 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4425 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4426 void do_klass(Klass* klass) { 4427 // If the klass has not been dirtied we know that there's 4428 // no references into the young gen and we can skip it. 4429 if (!_process_only_dirty || klass->has_modified_oops()) { 4430 // Clean the klass since we're going to scavenge all the metadata. 4431 klass->clear_modified_oops(); 4432 4433 // Tell the closure that this klass is the Klass to scavenge 4434 // and is the one to dirty if oops are left pointing into the young gen. 4435 _closure->set_scanned_klass(klass); 4436 4437 klass->oops_do(_closure); 4438 4439 _closure->set_scanned_klass(NULL); 4440 } 4441 _count++; 4442 } 4443 }; 4444 4445 class G1ParTask : public AbstractGangTask { 4446 protected: 4447 G1CollectedHeap* _g1h; 4448 RefToScanQueueSet *_queues; 4449 G1RootProcessor* _root_processor; 4450 ParallelTaskTerminator _terminator; 4451 uint _n_workers; 4452 4453 public: 4454 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 4455 : AbstractGangTask("G1 collection"), 4456 _g1h(g1h), 4457 _queues(task_queues), 4458 _root_processor(root_processor), 4459 _terminator(n_workers, _queues), 4460 _n_workers(n_workers) 4461 {} 4462 4463 RefToScanQueueSet* queues() { return _queues; } 4464 4465 RefToScanQueue *work_queue(int i) { 4466 return queues()->queue(i); 4467 } 4468 4469 ParallelTaskTerminator* terminator() { return &_terminator; } 4470 4471 // Helps out with CLD processing. 4472 // 4473 // During InitialMark we need to: 4474 // 1) Scavenge all CLDs for the young GC. 4475 // 2) Mark all objects directly reachable from strong CLDs. 4476 template <G1Mark do_mark_object> 4477 class G1CLDClosure : public CLDClosure { 4478 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure; 4479 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure; 4480 G1KlassScanClosure _klass_in_cld_closure; 4481 bool _claim; 4482 4483 public: 4484 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure, 4485 bool only_young, bool claim) 4486 : _oop_closure(oop_closure), 4487 _oop_in_klass_closure(oop_closure->g1(), 4488 oop_closure->pss(), 4489 oop_closure->rp()), 4490 _klass_in_cld_closure(&_oop_in_klass_closure, only_young), 4491 _claim(claim) { 4492 4493 } 4494 4495 void do_cld(ClassLoaderData* cld) { 4496 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim); 4497 } 4498 }; 4499 4500 void work(uint worker_id) { 4501 if (worker_id >= _n_workers) return; // no work needed this round 4502 4503 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime()); 4504 4505 { 4506 ResourceMark rm; 4507 HandleMark hm; 4508 4509 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4510 4511 G1ParScanThreadState pss(_g1h, worker_id, rp); 4512 4513 bool only_young = _g1h->collector_state()->gcs_are_young(); 4514 4515 // Non-IM young GC. 4516 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp); 4517 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl, 4518 only_young, // Only process dirty klasses. 4519 false); // No need to claim CLDs. 4520 // IM young GC. 4521 // Strong roots closures. 4522 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp); 4523 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl, 4524 false, // Process all klasses. 4525 true); // Need to claim CLDs. 4526 // Weak roots closures. 4527 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp); 4528 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl, 4529 false, // Process all klasses. 4530 true); // Need to claim CLDs. 4531 4532 OopClosure* strong_root_cl; 4533 OopClosure* weak_root_cl; 4534 CLDClosure* strong_cld_cl; 4535 CLDClosure* weak_cld_cl; 4536 4537 bool trace_metadata = false; 4538 4539 if (_g1h->collector_state()->during_initial_mark_pause()) { 4540 // We also need to mark copied objects. 4541 strong_root_cl = &scan_mark_root_cl; 4542 strong_cld_cl = &scan_mark_cld_cl; 4543 if (ClassUnloadingWithConcurrentMark) { 4544 weak_root_cl = &scan_mark_weak_root_cl; 4545 weak_cld_cl = &scan_mark_weak_cld_cl; 4546 trace_metadata = true; 4547 } else { 4548 weak_root_cl = &scan_mark_root_cl; 4549 weak_cld_cl = &scan_mark_cld_cl; 4550 } 4551 } else { 4552 strong_root_cl = &scan_only_root_cl; 4553 weak_root_cl = &scan_only_root_cl; 4554 strong_cld_cl = &scan_only_cld_cl; 4555 weak_cld_cl = &scan_only_cld_cl; 4556 } 4557 4558 pss.start_strong_roots(); 4559 4560 _root_processor->evacuate_roots(strong_root_cl, 4561 weak_root_cl, 4562 strong_cld_cl, 4563 weak_cld_cl, 4564 trace_metadata, 4565 worker_id); 4566 4567 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4568 _root_processor->scan_remembered_sets(&push_heap_rs_cl, 4569 weak_root_cl, 4570 worker_id); 4571 pss.end_strong_roots(); 4572 4573 { 4574 double start = os::elapsedTime(); 4575 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4576 evac.do_void(); 4577 double elapsed_sec = os::elapsedTime() - start; 4578 double term_sec = pss.term_time(); 4579 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 4580 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 4581 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts()); 4582 } 4583 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4584 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4585 4586 if (PrintTerminationStats) { 4587 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 4588 pss.print_termination_stats(); 4589 } 4590 4591 assert(pss.queue_is_empty(), "should be empty"); 4592 4593 // Close the inner scope so that the ResourceMark and HandleMark 4594 // destructors are executed here and are included as part of the 4595 // "GC Worker Time". 4596 } 4597 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 4598 } 4599 }; 4600 4601 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4602 private: 4603 BoolObjectClosure* _is_alive; 4604 int _initial_string_table_size; 4605 int _initial_symbol_table_size; 4606 4607 bool _process_strings; 4608 int _strings_processed; 4609 int _strings_removed; 4610 4611 bool _process_symbols; 4612 int _symbols_processed; 4613 int _symbols_removed; 4614 4615 public: 4616 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4617 AbstractGangTask("String/Symbol Unlinking"), 4618 _is_alive(is_alive), 4619 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4620 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4621 4622 _initial_string_table_size = StringTable::the_table()->table_size(); 4623 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4624 if (process_strings) { 4625 StringTable::clear_parallel_claimed_index(); 4626 } 4627 if (process_symbols) { 4628 SymbolTable::clear_parallel_claimed_index(); 4629 } 4630 } 4631 4632 ~G1StringSymbolTableUnlinkTask() { 4633 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4634 err_msg("claim value %d after unlink less than initial string table size %d", 4635 StringTable::parallel_claimed_index(), _initial_string_table_size)); 4636 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4637 err_msg("claim value %d after unlink less than initial symbol table size %d", 4638 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 4639 4640 if (G1TraceStringSymbolTableScrubbing) { 4641 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4642 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, " 4643 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed", 4644 strings_processed(), strings_removed(), 4645 symbols_processed(), symbols_removed()); 4646 } 4647 } 4648 4649 void work(uint worker_id) { 4650 int strings_processed = 0; 4651 int strings_removed = 0; 4652 int symbols_processed = 0; 4653 int symbols_removed = 0; 4654 if (_process_strings) { 4655 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4656 Atomic::add(strings_processed, &_strings_processed); 4657 Atomic::add(strings_removed, &_strings_removed); 4658 } 4659 if (_process_symbols) { 4660 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 4661 Atomic::add(symbols_processed, &_symbols_processed); 4662 Atomic::add(symbols_removed, &_symbols_removed); 4663 } 4664 } 4665 4666 size_t strings_processed() const { return (size_t)_strings_processed; } 4667 size_t strings_removed() const { return (size_t)_strings_removed; } 4668 4669 size_t symbols_processed() const { return (size_t)_symbols_processed; } 4670 size_t symbols_removed() const { return (size_t)_symbols_removed; } 4671 }; 4672 4673 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 4674 private: 4675 static Monitor* _lock; 4676 4677 BoolObjectClosure* const _is_alive; 4678 const bool _unloading_occurred; 4679 const uint _num_workers; 4680 4681 // Variables used to claim nmethods. 4682 nmethod* _first_nmethod; 4683 volatile nmethod* _claimed_nmethod; 4684 4685 // The list of nmethods that need to be processed by the second pass. 4686 volatile nmethod* _postponed_list; 4687 volatile uint _num_entered_barrier; 4688 4689 public: 4690 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 4691 _is_alive(is_alive), 4692 _unloading_occurred(unloading_occurred), 4693 _num_workers(num_workers), 4694 _first_nmethod(NULL), 4695 _claimed_nmethod(NULL), 4696 _postponed_list(NULL), 4697 _num_entered_barrier(0) 4698 { 4699 nmethod::increase_unloading_clock(); 4700 // Get first alive nmethod 4701 NMethodIterator iter = NMethodIterator(); 4702 if(iter.next_alive()) { 4703 _first_nmethod = iter.method(); 4704 } 4705 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 4706 } 4707 4708 ~G1CodeCacheUnloadingTask() { 4709 CodeCache::verify_clean_inline_caches(); 4710 4711 CodeCache::set_needs_cache_clean(false); 4712 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 4713 4714 CodeCache::verify_icholder_relocations(); 4715 } 4716 4717 private: 4718 void add_to_postponed_list(nmethod* nm) { 4719 nmethod* old; 4720 do { 4721 old = (nmethod*)_postponed_list; 4722 nm->set_unloading_next(old); 4723 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 4724 } 4725 4726 void clean_nmethod(nmethod* nm) { 4727 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 4728 4729 if (postponed) { 4730 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 4731 add_to_postponed_list(nm); 4732 } 4733 4734 // Mark that this thread has been cleaned/unloaded. 4735 // After this call, it will be safe to ask if this nmethod was unloaded or not. 4736 nm->set_unloading_clock(nmethod::global_unloading_clock()); 4737 } 4738 4739 void clean_nmethod_postponed(nmethod* nm) { 4740 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 4741 } 4742 4743 static const int MaxClaimNmethods = 16; 4744 4745 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 4746 nmethod* first; 4747 NMethodIterator last; 4748 4749 do { 4750 *num_claimed_nmethods = 0; 4751 4752 first = (nmethod*)_claimed_nmethod; 4753 last = NMethodIterator(first); 4754 4755 if (first != NULL) { 4756 4757 for (int i = 0; i < MaxClaimNmethods; i++) { 4758 if (!last.next_alive()) { 4759 break; 4760 } 4761 claimed_nmethods[i] = last.method(); 4762 (*num_claimed_nmethods)++; 4763 } 4764 } 4765 4766 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 4767 } 4768 4769 nmethod* claim_postponed_nmethod() { 4770 nmethod* claim; 4771 nmethod* next; 4772 4773 do { 4774 claim = (nmethod*)_postponed_list; 4775 if (claim == NULL) { 4776 return NULL; 4777 } 4778 4779 next = claim->unloading_next(); 4780 4781 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 4782 4783 return claim; 4784 } 4785 4786 public: 4787 // Mark that we're done with the first pass of nmethod cleaning. 4788 void barrier_mark(uint worker_id) { 4789 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4790 _num_entered_barrier++; 4791 if (_num_entered_barrier == _num_workers) { 4792 ml.notify_all(); 4793 } 4794 } 4795 4796 // See if we have to wait for the other workers to 4797 // finish their first-pass nmethod cleaning work. 4798 void barrier_wait(uint worker_id) { 4799 if (_num_entered_barrier < _num_workers) { 4800 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4801 while (_num_entered_barrier < _num_workers) { 4802 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 4803 } 4804 } 4805 } 4806 4807 // Cleaning and unloading of nmethods. Some work has to be postponed 4808 // to the second pass, when we know which nmethods survive. 4809 void work_first_pass(uint worker_id) { 4810 // The first nmethods is claimed by the first worker. 4811 if (worker_id == 0 && _first_nmethod != NULL) { 4812 clean_nmethod(_first_nmethod); 4813 _first_nmethod = NULL; 4814 } 4815 4816 int num_claimed_nmethods; 4817 nmethod* claimed_nmethods[MaxClaimNmethods]; 4818 4819 while (true) { 4820 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 4821 4822 if (num_claimed_nmethods == 0) { 4823 break; 4824 } 4825 4826 for (int i = 0; i < num_claimed_nmethods; i++) { 4827 clean_nmethod(claimed_nmethods[i]); 4828 } 4829 } 4830 } 4831 4832 void work_second_pass(uint worker_id) { 4833 nmethod* nm; 4834 // Take care of postponed nmethods. 4835 while ((nm = claim_postponed_nmethod()) != NULL) { 4836 clean_nmethod_postponed(nm); 4837 } 4838 } 4839 }; 4840 4841 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 4842 4843 class G1KlassCleaningTask : public StackObj { 4844 BoolObjectClosure* _is_alive; 4845 volatile jint _clean_klass_tree_claimed; 4846 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 4847 4848 public: 4849 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 4850 _is_alive(is_alive), 4851 _clean_klass_tree_claimed(0), 4852 _klass_iterator() { 4853 } 4854 4855 private: 4856 bool claim_clean_klass_tree_task() { 4857 if (_clean_klass_tree_claimed) { 4858 return false; 4859 } 4860 4861 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 4862 } 4863 4864 InstanceKlass* claim_next_klass() { 4865 Klass* klass; 4866 do { 4867 klass =_klass_iterator.next_klass(); 4868 } while (klass != NULL && !klass->oop_is_instance()); 4869 4870 return (InstanceKlass*)klass; 4871 } 4872 4873 public: 4874 4875 void clean_klass(InstanceKlass* ik) { 4876 ik->clean_implementors_list(_is_alive); 4877 ik->clean_method_data(_is_alive); 4878 4879 // G1 specific cleanup work that has 4880 // been moved here to be done in parallel. 4881 ik->clean_dependent_nmethods(); 4882 } 4883 4884 void work() { 4885 ResourceMark rm; 4886 4887 // One worker will clean the subklass/sibling klass tree. 4888 if (claim_clean_klass_tree_task()) { 4889 Klass::clean_subklass_tree(_is_alive); 4890 } 4891 4892 // All workers will help cleaning the classes, 4893 InstanceKlass* klass; 4894 while ((klass = claim_next_klass()) != NULL) { 4895 clean_klass(klass); 4896 } 4897 } 4898 }; 4899 4900 // To minimize the remark pause times, the tasks below are done in parallel. 4901 class G1ParallelCleaningTask : public AbstractGangTask { 4902 private: 4903 G1StringSymbolTableUnlinkTask _string_symbol_task; 4904 G1CodeCacheUnloadingTask _code_cache_task; 4905 G1KlassCleaningTask _klass_cleaning_task; 4906 4907 public: 4908 // The constructor is run in the VMThread. 4909 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 4910 AbstractGangTask("Parallel Cleaning"), 4911 _string_symbol_task(is_alive, process_strings, process_symbols), 4912 _code_cache_task(num_workers, is_alive, unloading_occurred), 4913 _klass_cleaning_task(is_alive) { 4914 } 4915 4916 // The parallel work done by all worker threads. 4917 void work(uint worker_id) { 4918 // Do first pass of code cache cleaning. 4919 _code_cache_task.work_first_pass(worker_id); 4920 4921 // Let the threads mark that the first pass is done. 4922 _code_cache_task.barrier_mark(worker_id); 4923 4924 // Clean the Strings and Symbols. 4925 _string_symbol_task.work(worker_id); 4926 4927 // Wait for all workers to finish the first code cache cleaning pass. 4928 _code_cache_task.barrier_wait(worker_id); 4929 4930 // Do the second code cache cleaning work, which realize on 4931 // the liveness information gathered during the first pass. 4932 _code_cache_task.work_second_pass(worker_id); 4933 4934 // Clean all klasses that were not unloaded. 4935 _klass_cleaning_task.work(); 4936 } 4937 }; 4938 4939 4940 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 4941 bool process_strings, 4942 bool process_symbols, 4943 bool class_unloading_occurred) { 4944 uint n_workers = workers()->active_workers(); 4945 4946 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 4947 n_workers, class_unloading_occurred); 4948 workers()->run_task(&g1_unlink_task); 4949 } 4950 4951 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 4952 bool process_strings, bool process_symbols) { 4953 { 4954 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 4955 workers()->run_task(&g1_unlink_task); 4956 } 4957 4958 if (G1StringDedup::is_enabled()) { 4959 G1StringDedup::unlink(is_alive); 4960 } 4961 } 4962 4963 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 4964 private: 4965 DirtyCardQueueSet* _queue; 4966 public: 4967 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 4968 4969 virtual void work(uint worker_id) { 4970 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4971 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 4972 4973 RedirtyLoggedCardTableEntryClosure cl; 4974 _queue->par_apply_closure_to_all_completed_buffers(&cl); 4975 4976 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed()); 4977 } 4978 }; 4979 4980 void G1CollectedHeap::redirty_logged_cards() { 4981 double redirty_logged_cards_start = os::elapsedTime(); 4982 4983 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 4984 dirty_card_queue_set().reset_for_par_iteration(); 4985 workers()->run_task(&redirty_task); 4986 4987 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 4988 dcq.merge_bufferlists(&dirty_card_queue_set()); 4989 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 4990 4991 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 4992 } 4993 4994 // Weak Reference Processing support 4995 4996 // An always "is_alive" closure that is used to preserve referents. 4997 // If the object is non-null then it's alive. Used in the preservation 4998 // of referent objects that are pointed to by reference objects 4999 // discovered by the CM ref processor. 5000 class G1AlwaysAliveClosure: public BoolObjectClosure { 5001 G1CollectedHeap* _g1; 5002 public: 5003 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5004 bool do_object_b(oop p) { 5005 if (p != NULL) { 5006 return true; 5007 } 5008 return false; 5009 } 5010 }; 5011 5012 bool G1STWIsAliveClosure::do_object_b(oop p) { 5013 // An object is reachable if it is outside the collection set, 5014 // or is inside and copied. 5015 return !_g1->is_in_cset(p) || p->is_forwarded(); 5016 } 5017 5018 // Non Copying Keep Alive closure 5019 class G1KeepAliveClosure: public OopClosure { 5020 G1CollectedHeap* _g1; 5021 public: 5022 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5023 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 5024 void do_oop(oop* p) { 5025 oop obj = *p; 5026 assert(obj != NULL, "the caller should have filtered out NULL values"); 5027 5028 const InCSetState cset_state = _g1->in_cset_state(obj); 5029 if (!cset_state.is_in_cset_or_humongous()) { 5030 return; 5031 } 5032 if (cset_state.is_in_cset()) { 5033 assert( obj->is_forwarded(), "invariant" ); 5034 *p = obj->forwardee(); 5035 } else { 5036 assert(!obj->is_forwarded(), "invariant" ); 5037 assert(cset_state.is_humongous(), 5038 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value())); 5039 _g1->set_humongous_is_live(obj); 5040 } 5041 } 5042 }; 5043 5044 // Copying Keep Alive closure - can be called from both 5045 // serial and parallel code as long as different worker 5046 // threads utilize different G1ParScanThreadState instances 5047 // and different queues. 5048 5049 class G1CopyingKeepAliveClosure: public OopClosure { 5050 G1CollectedHeap* _g1h; 5051 OopClosure* _copy_non_heap_obj_cl; 5052 G1ParScanThreadState* _par_scan_state; 5053 5054 public: 5055 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 5056 OopClosure* non_heap_obj_cl, 5057 G1ParScanThreadState* pss): 5058 _g1h(g1h), 5059 _copy_non_heap_obj_cl(non_heap_obj_cl), 5060 _par_scan_state(pss) 5061 {} 5062 5063 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 5064 virtual void do_oop( oop* p) { do_oop_work(p); } 5065 5066 template <class T> void do_oop_work(T* p) { 5067 oop obj = oopDesc::load_decode_heap_oop(p); 5068 5069 if (_g1h->is_in_cset_or_humongous(obj)) { 5070 // If the referent object has been forwarded (either copied 5071 // to a new location or to itself in the event of an 5072 // evacuation failure) then we need to update the reference 5073 // field and, if both reference and referent are in the G1 5074 // heap, update the RSet for the referent. 5075 // 5076 // If the referent has not been forwarded then we have to keep 5077 // it alive by policy. Therefore we have copy the referent. 5078 // 5079 // If the reference field is in the G1 heap then we can push 5080 // on the PSS queue. When the queue is drained (after each 5081 // phase of reference processing) the object and it's followers 5082 // will be copied, the reference field set to point to the 5083 // new location, and the RSet updated. Otherwise we need to 5084 // use the the non-heap or metadata closures directly to copy 5085 // the referent object and update the pointer, while avoiding 5086 // updating the RSet. 5087 5088 if (_g1h->is_in_g1_reserved(p)) { 5089 _par_scan_state->push_on_queue(p); 5090 } else { 5091 assert(!Metaspace::contains((const void*)p), 5092 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p))); 5093 _copy_non_heap_obj_cl->do_oop(p); 5094 } 5095 } 5096 } 5097 }; 5098 5099 // Serial drain queue closure. Called as the 'complete_gc' 5100 // closure for each discovered list in some of the 5101 // reference processing phases. 5102 5103 class G1STWDrainQueueClosure: public VoidClosure { 5104 protected: 5105 G1CollectedHeap* _g1h; 5106 G1ParScanThreadState* _par_scan_state; 5107 5108 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5109 5110 public: 5111 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5112 _g1h(g1h), 5113 _par_scan_state(pss) 5114 { } 5115 5116 void do_void() { 5117 G1ParScanThreadState* const pss = par_scan_state(); 5118 pss->trim_queue(); 5119 } 5120 }; 5121 5122 // Parallel Reference Processing closures 5123 5124 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5125 // processing during G1 evacuation pauses. 5126 5127 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5128 private: 5129 G1CollectedHeap* _g1h; 5130 RefToScanQueueSet* _queues; 5131 FlexibleWorkGang* _workers; 5132 uint _active_workers; 5133 5134 public: 5135 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5136 FlexibleWorkGang* workers, 5137 RefToScanQueueSet *task_queues, 5138 uint n_workers) : 5139 _g1h(g1h), 5140 _queues(task_queues), 5141 _workers(workers), 5142 _active_workers(n_workers) 5143 { 5144 assert(n_workers > 0, "shouldn't call this otherwise"); 5145 } 5146 5147 // Executes the given task using concurrent marking worker threads. 5148 virtual void execute(ProcessTask& task); 5149 virtual void execute(EnqueueTask& task); 5150 }; 5151 5152 // Gang task for possibly parallel reference processing 5153 5154 class G1STWRefProcTaskProxy: public AbstractGangTask { 5155 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5156 ProcessTask& _proc_task; 5157 G1CollectedHeap* _g1h; 5158 RefToScanQueueSet *_task_queues; 5159 ParallelTaskTerminator* _terminator; 5160 5161 public: 5162 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5163 G1CollectedHeap* g1h, 5164 RefToScanQueueSet *task_queues, 5165 ParallelTaskTerminator* terminator) : 5166 AbstractGangTask("Process reference objects in parallel"), 5167 _proc_task(proc_task), 5168 _g1h(g1h), 5169 _task_queues(task_queues), 5170 _terminator(terminator) 5171 {} 5172 5173 virtual void work(uint worker_id) { 5174 // The reference processing task executed by a single worker. 5175 ResourceMark rm; 5176 HandleMark hm; 5177 5178 G1STWIsAliveClosure is_alive(_g1h); 5179 5180 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5181 5182 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5183 5184 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5185 5186 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5187 5188 if (_g1h->collector_state()->during_initial_mark_pause()) { 5189 // We also need to mark copied objects. 5190 copy_non_heap_cl = ©_mark_non_heap_cl; 5191 } 5192 5193 // Keep alive closure. 5194 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5195 5196 // Complete GC closure 5197 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5198 5199 // Call the reference processing task's work routine. 5200 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5201 5202 // Note we cannot assert that the refs array is empty here as not all 5203 // of the processing tasks (specifically phase2 - pp2_work) execute 5204 // the complete_gc closure (which ordinarily would drain the queue) so 5205 // the queue may not be empty. 5206 } 5207 }; 5208 5209 // Driver routine for parallel reference processing. 5210 // Creates an instance of the ref processing gang 5211 // task and has the worker threads execute it. 5212 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5213 assert(_workers != NULL, "Need parallel worker threads."); 5214 5215 ParallelTaskTerminator terminator(_active_workers, _queues); 5216 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5217 5218 _workers->run_task(&proc_task_proxy); 5219 } 5220 5221 // Gang task for parallel reference enqueueing. 5222 5223 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5224 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5225 EnqueueTask& _enq_task; 5226 5227 public: 5228 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5229 AbstractGangTask("Enqueue reference objects in parallel"), 5230 _enq_task(enq_task) 5231 { } 5232 5233 virtual void work(uint worker_id) { 5234 _enq_task.work(worker_id); 5235 } 5236 }; 5237 5238 // Driver routine for parallel reference enqueueing. 5239 // Creates an instance of the ref enqueueing gang 5240 // task and has the worker threads execute it. 5241 5242 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5243 assert(_workers != NULL, "Need parallel worker threads."); 5244 5245 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5246 5247 _workers->run_task(&enq_task_proxy); 5248 } 5249 5250 // End of weak reference support closures 5251 5252 // Abstract task used to preserve (i.e. copy) any referent objects 5253 // that are in the collection set and are pointed to by reference 5254 // objects discovered by the CM ref processor. 5255 5256 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5257 protected: 5258 G1CollectedHeap* _g1h; 5259 RefToScanQueueSet *_queues; 5260 ParallelTaskTerminator _terminator; 5261 uint _n_workers; 5262 5263 public: 5264 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, uint workers, RefToScanQueueSet *task_queues) : 5265 AbstractGangTask("ParPreserveCMReferents"), 5266 _g1h(g1h), 5267 _queues(task_queues), 5268 _terminator(workers, _queues), 5269 _n_workers(workers) 5270 { } 5271 5272 void work(uint worker_id) { 5273 ResourceMark rm; 5274 HandleMark hm; 5275 5276 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5277 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5278 5279 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5280 5281 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5282 5283 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5284 5285 if (_g1h->collector_state()->during_initial_mark_pause()) { 5286 // We also need to mark copied objects. 5287 copy_non_heap_cl = ©_mark_non_heap_cl; 5288 } 5289 5290 // Is alive closure 5291 G1AlwaysAliveClosure always_alive(_g1h); 5292 5293 // Copying keep alive closure. Applied to referent objects that need 5294 // to be copied. 5295 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5296 5297 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5298 5299 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5300 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5301 5302 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5303 // So this must be true - but assert just in case someone decides to 5304 // change the worker ids. 5305 assert(worker_id < limit, "sanity"); 5306 assert(!rp->discovery_is_atomic(), "check this code"); 5307 5308 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5309 for (uint idx = worker_id; idx < limit; idx += stride) { 5310 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5311 5312 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5313 while (iter.has_next()) { 5314 // Since discovery is not atomic for the CM ref processor, we 5315 // can see some null referent objects. 5316 iter.load_ptrs(DEBUG_ONLY(true)); 5317 oop ref = iter.obj(); 5318 5319 // This will filter nulls. 5320 if (iter.is_referent_alive()) { 5321 iter.make_referent_alive(); 5322 } 5323 iter.move_to_next(); 5324 } 5325 } 5326 5327 // Drain the queue - which may cause stealing 5328 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5329 drain_queue.do_void(); 5330 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5331 assert(pss.queue_is_empty(), "should be"); 5332 } 5333 }; 5334 5335 // Weak Reference processing during an evacuation pause (part 1). 5336 void G1CollectedHeap::process_discovered_references() { 5337 double ref_proc_start = os::elapsedTime(); 5338 5339 ReferenceProcessor* rp = _ref_processor_stw; 5340 assert(rp->discovery_enabled(), "should have been enabled"); 5341 5342 // Any reference objects, in the collection set, that were 'discovered' 5343 // by the CM ref processor should have already been copied (either by 5344 // applying the external root copy closure to the discovered lists, or 5345 // by following an RSet entry). 5346 // 5347 // But some of the referents, that are in the collection set, that these 5348 // reference objects point to may not have been copied: the STW ref 5349 // processor would have seen that the reference object had already 5350 // been 'discovered' and would have skipped discovering the reference, 5351 // but would not have treated the reference object as a regular oop. 5352 // As a result the copy closure would not have been applied to the 5353 // referent object. 5354 // 5355 // We need to explicitly copy these referent objects - the references 5356 // will be processed at the end of remarking. 5357 // 5358 // We also need to do this copying before we process the reference 5359 // objects discovered by the STW ref processor in case one of these 5360 // referents points to another object which is also referenced by an 5361 // object discovered by the STW ref processor. 5362 5363 uint no_of_gc_workers = workers()->active_workers(); 5364 5365 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5366 no_of_gc_workers, 5367 _task_queues); 5368 5369 workers()->run_task(&keep_cm_referents); 5370 5371 // Closure to test whether a referent is alive. 5372 G1STWIsAliveClosure is_alive(this); 5373 5374 // Even when parallel reference processing is enabled, the processing 5375 // of JNI refs is serial and performed serially by the current thread 5376 // rather than by a worker. The following PSS will be used for processing 5377 // JNI refs. 5378 5379 // Use only a single queue for this PSS. 5380 G1ParScanThreadState pss(this, 0, NULL); 5381 assert(pss.queue_is_empty(), "pre-condition"); 5382 5383 // We do not embed a reference processor in the copying/scanning 5384 // closures while we're actually processing the discovered 5385 // reference objects. 5386 5387 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5388 5389 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5390 5391 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5392 5393 if (collector_state()->during_initial_mark_pause()) { 5394 // We also need to mark copied objects. 5395 copy_non_heap_cl = ©_mark_non_heap_cl; 5396 } 5397 5398 // Keep alive closure. 5399 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss); 5400 5401 // Serial Complete GC closure 5402 G1STWDrainQueueClosure drain_queue(this, &pss); 5403 5404 // Setup the soft refs policy... 5405 rp->setup_policy(false); 5406 5407 ReferenceProcessorStats stats; 5408 if (!rp->processing_is_mt()) { 5409 // Serial reference processing... 5410 stats = rp->process_discovered_references(&is_alive, 5411 &keep_alive, 5412 &drain_queue, 5413 NULL, 5414 _gc_timer_stw, 5415 _gc_tracer_stw->gc_id()); 5416 } else { 5417 // Parallel reference processing 5418 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5419 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5420 5421 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5422 stats = rp->process_discovered_references(&is_alive, 5423 &keep_alive, 5424 &drain_queue, 5425 &par_task_executor, 5426 _gc_timer_stw, 5427 _gc_tracer_stw->gc_id()); 5428 } 5429 5430 _gc_tracer_stw->report_gc_reference_stats(stats); 5431 5432 // We have completed copying any necessary live referent objects. 5433 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5434 5435 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5436 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5437 } 5438 5439 // Weak Reference processing during an evacuation pause (part 2). 5440 void G1CollectedHeap::enqueue_discovered_references() { 5441 double ref_enq_start = os::elapsedTime(); 5442 5443 ReferenceProcessor* rp = _ref_processor_stw; 5444 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5445 5446 // Now enqueue any remaining on the discovered lists on to 5447 // the pending list. 5448 if (!rp->processing_is_mt()) { 5449 // Serial reference processing... 5450 rp->enqueue_discovered_references(); 5451 } else { 5452 // Parallel reference enqueueing 5453 5454 uint n_workers = workers()->active_workers(); 5455 5456 assert(rp->num_q() == n_workers, "sanity"); 5457 assert(n_workers <= rp->max_num_q(), "sanity"); 5458 5459 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, n_workers); 5460 rp->enqueue_discovered_references(&par_task_executor); 5461 } 5462 5463 rp->verify_no_references_recorded(); 5464 assert(!rp->discovery_enabled(), "should have been disabled"); 5465 5466 // FIXME 5467 // CM's reference processing also cleans up the string and symbol tables. 5468 // Should we do that here also? We could, but it is a serial operation 5469 // and could significantly increase the pause time. 5470 5471 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5472 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5473 } 5474 5475 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5476 _expand_heap_after_alloc_failure = true; 5477 _evacuation_failed = false; 5478 5479 // Should G1EvacuationFailureALot be in effect for this GC? 5480 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5481 5482 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5483 5484 // Disable the hot card cache. 5485 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5486 hot_card_cache->reset_hot_cache_claimed_index(); 5487 hot_card_cache->set_use_cache(false); 5488 5489 const uint n_workers = workers()->active_workers(); 5490 5491 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5492 double start_par_time_sec = os::elapsedTime(); 5493 double end_par_time_sec; 5494 5495 { 5496 G1RootProcessor root_processor(this, n_workers); 5497 G1ParTask g1_par_task(this, _task_queues, &root_processor, n_workers); 5498 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5499 if (collector_state()->during_initial_mark_pause()) { 5500 ClassLoaderDataGraph::clear_claimed_marks(); 5501 } 5502 5503 // The individual threads will set their evac-failure closures. 5504 if (PrintTerminationStats) { 5505 G1ParScanThreadState::print_termination_stats_hdr(); 5506 } 5507 5508 workers()->run_task(&g1_par_task); 5509 end_par_time_sec = os::elapsedTime(); 5510 5511 // Closing the inner scope will execute the destructor 5512 // for the G1RootProcessor object. We record the current 5513 // elapsed time before closing the scope so that time 5514 // taken for the destructor is NOT included in the 5515 // reported parallel time. 5516 } 5517 5518 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 5519 5520 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5521 phase_times->record_par_time(par_time_ms); 5522 5523 double code_root_fixup_time_ms = 5524 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5525 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 5526 5527 // Process any discovered reference objects - we have 5528 // to do this _before_ we retire the GC alloc regions 5529 // as we may have to copy some 'reachable' referent 5530 // objects (and their reachable sub-graphs) that were 5531 // not copied during the pause. 5532 process_discovered_references(); 5533 5534 if (G1StringDedup::is_enabled()) { 5535 double fixup_start = os::elapsedTime(); 5536 5537 G1STWIsAliveClosure is_alive(this); 5538 G1KeepAliveClosure keep_alive(this); 5539 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times); 5540 5541 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 5542 phase_times->record_string_dedup_fixup_time(fixup_time_ms); 5543 } 5544 5545 record_obj_copy_mem_stats(); 5546 5547 _allocator->release_gc_alloc_regions(evacuation_info); 5548 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5549 5550 // Reset and re-enable the hot card cache. 5551 // Note the counts for the cards in the regions in the 5552 // collection set are reset when the collection set is freed. 5553 hot_card_cache->reset_hot_cache(); 5554 hot_card_cache->set_use_cache(true); 5555 5556 purge_code_root_memory(); 5557 5558 if (evacuation_failed()) { 5559 remove_self_forwarding_pointers(); 5560 5561 // Reset the G1EvacuationFailureALot counters and flags 5562 // Note: the values are reset only when an actual 5563 // evacuation failure occurs. 5564 NOT_PRODUCT(reset_evacuation_should_fail();) 5565 } 5566 5567 // Enqueue any remaining references remaining on the STW 5568 // reference processor's discovered lists. We need to do 5569 // this after the card table is cleaned (and verified) as 5570 // the act of enqueueing entries on to the pending list 5571 // will log these updates (and dirty their associated 5572 // cards). We need these updates logged to update any 5573 // RSets. 5574 enqueue_discovered_references(); 5575 5576 redirty_logged_cards(); 5577 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5578 } 5579 5580 void G1CollectedHeap::record_obj_copy_mem_stats() { 5581 EventGCG1EvacuationYoungStatistics surv_evt; 5582 if (surv_evt.should_commit()) { 5583 surv_evt.set_gcId(GCId::peek().id()); 5584 surv_evt.set_allocated(_survivor_evac_stats.allocated() * HeapWordSize); 5585 surv_evt.set_wasted(_survivor_evac_stats.wasted() * HeapWordSize); 5586 surv_evt.set_used(_survivor_evac_stats.used() * HeapWordSize); 5587 surv_evt.set_undoWaste(_survivor_evac_stats.undo_wasted() * HeapWordSize); 5588 surv_evt.set_regionEndWaste(_survivor_evac_stats.region_end_waste() * HeapWordSize); 5589 surv_evt.set_regionsRefilled(_survivor_evac_stats.regions_refilled()); 5590 surv_evt.set_directAllocated(_survivor_evac_stats.direct_allocated() * HeapWordSize); 5591 surv_evt.set_failureUsed(_survivor_evac_stats.failure_used() * HeapWordSize); 5592 surv_evt.set_failureWaste(_survivor_evac_stats.failure_waste() * HeapWordSize); 5593 surv_evt.commit(); 5594 } 5595 5596 EventGCG1EvacuationOldStatistics old_evt; 5597 if (old_evt.should_commit()) { 5598 old_evt.set_gcId(GCId::peek().id()); 5599 old_evt.set_allocated(_old_evac_stats.allocated() * HeapWordSize); 5600 old_evt.set_wasted(_old_evac_stats.wasted() * HeapWordSize); 5601 old_evt.set_used(_old_evac_stats.used() * HeapWordSize); 5602 old_evt.set_undoWaste(_old_evac_stats.undo_wasted() * HeapWordSize); 5603 old_evt.set_regionEndWaste(_old_evac_stats.region_end_waste() * HeapWordSize); 5604 old_evt.set_regionsRefilled(_old_evac_stats.regions_refilled()); 5605 old_evt.set_directAllocated(_old_evac_stats.direct_allocated() * HeapWordSize); 5606 old_evt.set_failureUsed(_old_evac_stats.failure_used() * HeapWordSize); 5607 old_evt.set_failureWaste(_old_evac_stats.failure_waste() * HeapWordSize); 5608 old_evt.commit(); 5609 } 5610 } 5611 5612 void G1CollectedHeap::free_region(HeapRegion* hr, 5613 FreeRegionList* free_list, 5614 bool par, 5615 bool locked) { 5616 assert(!hr->is_free(), "the region should not be free"); 5617 assert(!hr->is_empty(), "the region should not be empty"); 5618 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 5619 assert(free_list != NULL, "pre-condition"); 5620 5621 if (G1VerifyBitmaps) { 5622 MemRegion mr(hr->bottom(), hr->end()); 5623 concurrent_mark()->clearRangePrevBitmap(mr); 5624 } 5625 5626 // Clear the card counts for this region. 5627 // Note: we only need to do this if the region is not young 5628 // (since we don't refine cards in young regions). 5629 if (!hr->is_young()) { 5630 _cg1r->hot_card_cache()->reset_card_counts(hr); 5631 } 5632 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5633 free_list->add_ordered(hr); 5634 } 5635 5636 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5637 FreeRegionList* free_list, 5638 bool par) { 5639 assert(hr->is_starts_humongous(), "this is only for starts humongous regions"); 5640 assert(free_list != NULL, "pre-condition"); 5641 5642 size_t hr_capacity = hr->capacity(); 5643 // We need to read this before we make the region non-humongous, 5644 // otherwise the information will be gone. 5645 uint last_index = hr->last_hc_index(); 5646 hr->clear_humongous(); 5647 free_region(hr, free_list, par); 5648 5649 uint i = hr->hrm_index() + 1; 5650 while (i < last_index) { 5651 HeapRegion* curr_hr = region_at(i); 5652 assert(curr_hr->is_continues_humongous(), "invariant"); 5653 curr_hr->clear_humongous(); 5654 free_region(curr_hr, free_list, par); 5655 i += 1; 5656 } 5657 } 5658 5659 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 5660 const HeapRegionSetCount& humongous_regions_removed) { 5661 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5662 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5663 _old_set.bulk_remove(old_regions_removed); 5664 _humongous_set.bulk_remove(humongous_regions_removed); 5665 } 5666 5667 } 5668 5669 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 5670 assert(list != NULL, "list can't be null"); 5671 if (!list->is_empty()) { 5672 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5673 _hrm.insert_list_into_free_list(list); 5674 } 5675 } 5676 5677 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 5678 decrease_used(bytes); 5679 } 5680 5681 class G1ParCleanupCTTask : public AbstractGangTask { 5682 G1SATBCardTableModRefBS* _ct_bs; 5683 G1CollectedHeap* _g1h; 5684 HeapRegion* volatile _su_head; 5685 public: 5686 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 5687 G1CollectedHeap* g1h) : 5688 AbstractGangTask("G1 Par Cleanup CT Task"), 5689 _ct_bs(ct_bs), _g1h(g1h) { } 5690 5691 void work(uint worker_id) { 5692 HeapRegion* r; 5693 while (r = _g1h->pop_dirty_cards_region()) { 5694 clear_cards(r); 5695 } 5696 } 5697 5698 void clear_cards(HeapRegion* r) { 5699 // Cards of the survivors should have already been dirtied. 5700 if (!r->is_survivor()) { 5701 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5702 } 5703 } 5704 }; 5705 5706 #ifndef PRODUCT 5707 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5708 G1CollectedHeap* _g1h; 5709 G1SATBCardTableModRefBS* _ct_bs; 5710 public: 5711 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 5712 : _g1h(g1h), _ct_bs(ct_bs) { } 5713 virtual bool doHeapRegion(HeapRegion* r) { 5714 if (r->is_survivor()) { 5715 _g1h->verify_dirty_region(r); 5716 } else { 5717 _g1h->verify_not_dirty_region(r); 5718 } 5719 return false; 5720 } 5721 }; 5722 5723 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5724 // All of the region should be clean. 5725 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5726 MemRegion mr(hr->bottom(), hr->end()); 5727 ct_bs->verify_not_dirty_region(mr); 5728 } 5729 5730 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5731 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5732 // dirty allocated blocks as they allocate them. The thread that 5733 // retires each region and replaces it with a new one will do a 5734 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5735 // not dirty that area (one less thing to have to do while holding 5736 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5737 // is dirty. 5738 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5739 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5740 if (hr->is_young()) { 5741 ct_bs->verify_g1_young_region(mr); 5742 } else { 5743 ct_bs->verify_dirty_region(mr); 5744 } 5745 } 5746 5747 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5748 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5749 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5750 verify_dirty_region(hr); 5751 } 5752 } 5753 5754 void G1CollectedHeap::verify_dirty_young_regions() { 5755 verify_dirty_young_list(_young_list->first_region()); 5756 } 5757 5758 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 5759 HeapWord* tams, HeapWord* end) { 5760 guarantee(tams <= end, 5761 err_msg("tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end))); 5762 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 5763 if (result < end) { 5764 gclog_or_tty->cr(); 5765 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT, 5766 bitmap_name, p2i(result)); 5767 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT, 5768 bitmap_name, p2i(tams), p2i(end)); 5769 return false; 5770 } 5771 return true; 5772 } 5773 5774 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 5775 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 5776 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 5777 5778 HeapWord* bottom = hr->bottom(); 5779 HeapWord* ptams = hr->prev_top_at_mark_start(); 5780 HeapWord* ntams = hr->next_top_at_mark_start(); 5781 HeapWord* end = hr->end(); 5782 5783 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 5784 5785 bool res_n = true; 5786 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 5787 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 5788 // if we happen to be in that state. 5789 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) { 5790 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 5791 } 5792 if (!res_p || !res_n) { 5793 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT, 5794 HR_FORMAT_PARAMS(hr)); 5795 gclog_or_tty->print_cr("#### Caller: %s", caller); 5796 return false; 5797 } 5798 return true; 5799 } 5800 5801 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 5802 if (!G1VerifyBitmaps) return; 5803 5804 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 5805 } 5806 5807 class G1VerifyBitmapClosure : public HeapRegionClosure { 5808 private: 5809 const char* _caller; 5810 G1CollectedHeap* _g1h; 5811 bool _failures; 5812 5813 public: 5814 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 5815 _caller(caller), _g1h(g1h), _failures(false) { } 5816 5817 bool failures() { return _failures; } 5818 5819 virtual bool doHeapRegion(HeapRegion* hr) { 5820 if (hr->is_continues_humongous()) return false; 5821 5822 bool result = _g1h->verify_bitmaps(_caller, hr); 5823 if (!result) { 5824 _failures = true; 5825 } 5826 return false; 5827 } 5828 }; 5829 5830 void G1CollectedHeap::check_bitmaps(const char* caller) { 5831 if (!G1VerifyBitmaps) return; 5832 5833 G1VerifyBitmapClosure cl(caller, this); 5834 heap_region_iterate(&cl); 5835 guarantee(!cl.failures(), "bitmap verification"); 5836 } 5837 5838 class G1CheckCSetFastTableClosure : public HeapRegionClosure { 5839 private: 5840 bool _failures; 5841 public: 5842 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { } 5843 5844 virtual bool doHeapRegion(HeapRegion* hr) { 5845 uint i = hr->hrm_index(); 5846 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i); 5847 if (hr->is_humongous()) { 5848 if (hr->in_collection_set()) { 5849 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i); 5850 _failures = true; 5851 return true; 5852 } 5853 if (cset_state.is_in_cset()) { 5854 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i); 5855 _failures = true; 5856 return true; 5857 } 5858 if (hr->is_continues_humongous() && cset_state.is_humongous()) { 5859 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i); 5860 _failures = true; 5861 return true; 5862 } 5863 } else { 5864 if (cset_state.is_humongous()) { 5865 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i); 5866 _failures = true; 5867 return true; 5868 } 5869 if (hr->in_collection_set() != cset_state.is_in_cset()) { 5870 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u", 5871 hr->in_collection_set(), cset_state.value(), i); 5872 _failures = true; 5873 return true; 5874 } 5875 if (cset_state.is_in_cset()) { 5876 if (hr->is_young() != (cset_state.is_young())) { 5877 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u", 5878 hr->is_young(), cset_state.value(), i); 5879 _failures = true; 5880 return true; 5881 } 5882 if (hr->is_old() != (cset_state.is_old())) { 5883 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u", 5884 hr->is_old(), cset_state.value(), i); 5885 _failures = true; 5886 return true; 5887 } 5888 } 5889 } 5890 return false; 5891 } 5892 5893 bool failures() const { return _failures; } 5894 }; 5895 5896 bool G1CollectedHeap::check_cset_fast_test() { 5897 G1CheckCSetFastTableClosure cl; 5898 _hrm.iterate(&cl); 5899 return !cl.failures(); 5900 } 5901 #endif // PRODUCT 5902 5903 void G1CollectedHeap::cleanUpCardTable() { 5904 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5905 double start = os::elapsedTime(); 5906 5907 { 5908 // Iterate over the dirty cards region list. 5909 G1ParCleanupCTTask cleanup_task(ct_bs, this); 5910 5911 workers()->run_task(&cleanup_task); 5912 #ifndef PRODUCT 5913 if (G1VerifyCTCleanup || VerifyAfterGC) { 5914 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 5915 heap_region_iterate(&cleanup_verifier); 5916 } 5917 #endif 5918 } 5919 5920 double elapsed = os::elapsedTime() - start; 5921 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 5922 } 5923 5924 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 5925 size_t pre_used = 0; 5926 FreeRegionList local_free_list("Local List for CSet Freeing"); 5927 5928 double young_time_ms = 0.0; 5929 double non_young_time_ms = 0.0; 5930 5931 // Since the collection set is a superset of the the young list, 5932 // all we need to do to clear the young list is clear its 5933 // head and length, and unlink any young regions in the code below 5934 _young_list->clear(); 5935 5936 G1CollectorPolicy* policy = g1_policy(); 5937 5938 double start_sec = os::elapsedTime(); 5939 bool non_young = true; 5940 5941 HeapRegion* cur = cs_head; 5942 int age_bound = -1; 5943 size_t rs_lengths = 0; 5944 5945 while (cur != NULL) { 5946 assert(!is_on_master_free_list(cur), "sanity"); 5947 if (non_young) { 5948 if (cur->is_young()) { 5949 double end_sec = os::elapsedTime(); 5950 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5951 non_young_time_ms += elapsed_ms; 5952 5953 start_sec = os::elapsedTime(); 5954 non_young = false; 5955 } 5956 } else { 5957 if (!cur->is_young()) { 5958 double end_sec = os::elapsedTime(); 5959 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5960 young_time_ms += elapsed_ms; 5961 5962 start_sec = os::elapsedTime(); 5963 non_young = true; 5964 } 5965 } 5966 5967 rs_lengths += cur->rem_set()->occupied_locked(); 5968 5969 HeapRegion* next = cur->next_in_collection_set(); 5970 assert(cur->in_collection_set(), "bad CS"); 5971 cur->set_next_in_collection_set(NULL); 5972 clear_in_cset(cur); 5973 5974 if (cur->is_young()) { 5975 int index = cur->young_index_in_cset(); 5976 assert(index != -1, "invariant"); 5977 assert((uint) index < policy->young_cset_region_length(), "invariant"); 5978 size_t words_survived = _surviving_young_words[index]; 5979 cur->record_surv_words_in_group(words_survived); 5980 5981 // At this point the we have 'popped' cur from the collection set 5982 // (linked via next_in_collection_set()) but it is still in the 5983 // young list (linked via next_young_region()). Clear the 5984 // _next_young_region field. 5985 cur->set_next_young_region(NULL); 5986 } else { 5987 int index = cur->young_index_in_cset(); 5988 assert(index == -1, "invariant"); 5989 } 5990 5991 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 5992 (!cur->is_young() && cur->young_index_in_cset() == -1), 5993 "invariant" ); 5994 5995 if (!cur->evacuation_failed()) { 5996 MemRegion used_mr = cur->used_region(); 5997 5998 // And the region is empty. 5999 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 6000 pre_used += cur->used(); 6001 free_region(cur, &local_free_list, false /* par */, true /* locked */); 6002 } else { 6003 cur->uninstall_surv_rate_group(); 6004 if (cur->is_young()) { 6005 cur->set_young_index_in_cset(-1); 6006 } 6007 cur->set_evacuation_failed(false); 6008 // The region is now considered to be old. 6009 cur->set_old(); 6010 // Do some allocation statistics accounting. Regions that failed evacuation 6011 // are always made old, so there is no need to update anything in the young 6012 // gen statistics, but we need to update old gen statistics. 6013 size_t used_words = cur->marked_bytes() / HeapWordSize; 6014 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words); 6015 _old_set.add(cur); 6016 evacuation_info.increment_collectionset_used_after(cur->used()); 6017 } 6018 cur = next; 6019 } 6020 6021 evacuation_info.set_regions_freed(local_free_list.length()); 6022 policy->record_max_rs_lengths(rs_lengths); 6023 policy->cset_regions_freed(); 6024 6025 double end_sec = os::elapsedTime(); 6026 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6027 6028 if (non_young) { 6029 non_young_time_ms += elapsed_ms; 6030 } else { 6031 young_time_ms += elapsed_ms; 6032 } 6033 6034 prepend_to_freelist(&local_free_list); 6035 decrement_summary_bytes(pre_used); 6036 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 6037 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 6038 } 6039 6040 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 6041 private: 6042 FreeRegionList* _free_region_list; 6043 HeapRegionSet* _proxy_set; 6044 HeapRegionSetCount _humongous_regions_removed; 6045 size_t _freed_bytes; 6046 public: 6047 6048 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 6049 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 6050 } 6051 6052 virtual bool doHeapRegion(HeapRegion* r) { 6053 if (!r->is_starts_humongous()) { 6054 return false; 6055 } 6056 6057 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 6058 6059 oop obj = (oop)r->bottom(); 6060 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 6061 6062 // The following checks whether the humongous object is live are sufficient. 6063 // The main additional check (in addition to having a reference from the roots 6064 // or the young gen) is whether the humongous object has a remembered set entry. 6065 // 6066 // A humongous object cannot be live if there is no remembered set for it 6067 // because: 6068 // - there can be no references from within humongous starts regions referencing 6069 // the object because we never allocate other objects into them. 6070 // (I.e. there are no intra-region references that may be missed by the 6071 // remembered set) 6072 // - as soon there is a remembered set entry to the humongous starts region 6073 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 6074 // until the end of a concurrent mark. 6075 // 6076 // It is not required to check whether the object has been found dead by marking 6077 // or not, in fact it would prevent reclamation within a concurrent cycle, as 6078 // all objects allocated during that time are considered live. 6079 // SATB marking is even more conservative than the remembered set. 6080 // So if at this point in the collection there is no remembered set entry, 6081 // nobody has a reference to it. 6082 // At the start of collection we flush all refinement logs, and remembered sets 6083 // are completely up-to-date wrt to references to the humongous object. 6084 // 6085 // Other implementation considerations: 6086 // - never consider object arrays at this time because they would pose 6087 // considerable effort for cleaning up the the remembered sets. This is 6088 // required because stale remembered sets might reference locations that 6089 // are currently allocated into. 6090 uint region_idx = r->hrm_index(); 6091 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 6092 !r->rem_set()->is_empty()) { 6093 6094 if (G1TraceEagerReclaimHumongousObjects) { 6095 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", 6096 region_idx, 6097 (size_t)obj->size() * HeapWordSize, 6098 p2i(r->bottom()), 6099 r->region_num(), 6100 r->rem_set()->occupied(), 6101 r->rem_set()->strong_code_roots_list_length(), 6102 next_bitmap->isMarked(r->bottom()), 6103 g1h->is_humongous_reclaim_candidate(region_idx), 6104 obj->is_typeArray() 6105 ); 6106 } 6107 6108 return false; 6109 } 6110 6111 guarantee(obj->is_typeArray(), 6112 err_msg("Only eagerly reclaiming type arrays is supported, but the object " 6113 PTR_FORMAT " is not.", 6114 p2i(r->bottom()))); 6115 6116 if (G1TraceEagerReclaimHumongousObjects) { 6117 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", 6118 region_idx, 6119 (size_t)obj->size() * HeapWordSize, 6120 p2i(r->bottom()), 6121 r->region_num(), 6122 r->rem_set()->occupied(), 6123 r->rem_set()->strong_code_roots_list_length(), 6124 next_bitmap->isMarked(r->bottom()), 6125 g1h->is_humongous_reclaim_candidate(region_idx), 6126 obj->is_typeArray() 6127 ); 6128 } 6129 // Need to clear mark bit of the humongous object if already set. 6130 if (next_bitmap->isMarked(r->bottom())) { 6131 next_bitmap->clear(r->bottom()); 6132 } 6133 _freed_bytes += r->used(); 6134 r->set_containing_set(NULL); 6135 _humongous_regions_removed.increment(1u, r->capacity()); 6136 g1h->free_humongous_region(r, _free_region_list, false); 6137 6138 return false; 6139 } 6140 6141 HeapRegionSetCount& humongous_free_count() { 6142 return _humongous_regions_removed; 6143 } 6144 6145 size_t bytes_freed() const { 6146 return _freed_bytes; 6147 } 6148 6149 size_t humongous_reclaimed() const { 6150 return _humongous_regions_removed.length(); 6151 } 6152 }; 6153 6154 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 6155 assert_at_safepoint(true); 6156 6157 if (!G1EagerReclaimHumongousObjects || 6158 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) { 6159 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 6160 return; 6161 } 6162 6163 double start_time = os::elapsedTime(); 6164 6165 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 6166 6167 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 6168 heap_region_iterate(&cl); 6169 6170 HeapRegionSetCount empty_set; 6171 remove_from_old_sets(empty_set, cl.humongous_free_count()); 6172 6173 G1HRPrinter* hrp = hr_printer(); 6174 if (hrp->is_active()) { 6175 FreeRegionListIterator iter(&local_cleanup_list); 6176 while (iter.more_available()) { 6177 HeapRegion* hr = iter.get_next(); 6178 hrp->cleanup(hr); 6179 } 6180 } 6181 6182 prepend_to_freelist(&local_cleanup_list); 6183 decrement_summary_bytes(cl.bytes_freed()); 6184 6185 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 6186 cl.humongous_reclaimed()); 6187 } 6188 6189 // This routine is similar to the above but does not record 6190 // any policy statistics or update free lists; we are abandoning 6191 // the current incremental collection set in preparation of a 6192 // full collection. After the full GC we will start to build up 6193 // the incremental collection set again. 6194 // This is only called when we're doing a full collection 6195 // and is immediately followed by the tearing down of the young list. 6196 6197 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6198 HeapRegion* cur = cs_head; 6199 6200 while (cur != NULL) { 6201 HeapRegion* next = cur->next_in_collection_set(); 6202 assert(cur->in_collection_set(), "bad CS"); 6203 cur->set_next_in_collection_set(NULL); 6204 clear_in_cset(cur); 6205 cur->set_young_index_in_cset(-1); 6206 cur = next; 6207 } 6208 } 6209 6210 void G1CollectedHeap::set_free_regions_coming() { 6211 if (G1ConcRegionFreeingVerbose) { 6212 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6213 "setting free regions coming"); 6214 } 6215 6216 assert(!free_regions_coming(), "pre-condition"); 6217 _free_regions_coming = true; 6218 } 6219 6220 void G1CollectedHeap::reset_free_regions_coming() { 6221 assert(free_regions_coming(), "pre-condition"); 6222 6223 { 6224 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6225 _free_regions_coming = false; 6226 SecondaryFreeList_lock->notify_all(); 6227 } 6228 6229 if (G1ConcRegionFreeingVerbose) { 6230 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6231 "reset free regions coming"); 6232 } 6233 } 6234 6235 void G1CollectedHeap::wait_while_free_regions_coming() { 6236 // Most of the time we won't have to wait, so let's do a quick test 6237 // first before we take the lock. 6238 if (!free_regions_coming()) { 6239 return; 6240 } 6241 6242 if (G1ConcRegionFreeingVerbose) { 6243 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6244 "waiting for free regions"); 6245 } 6246 6247 { 6248 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6249 while (free_regions_coming()) { 6250 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6251 } 6252 } 6253 6254 if (G1ConcRegionFreeingVerbose) { 6255 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6256 "done waiting for free regions"); 6257 } 6258 } 6259 6260 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6261 _young_list->push_region(hr); 6262 } 6263 6264 class NoYoungRegionsClosure: public HeapRegionClosure { 6265 private: 6266 bool _success; 6267 public: 6268 NoYoungRegionsClosure() : _success(true) { } 6269 bool doHeapRegion(HeapRegion* r) { 6270 if (r->is_young()) { 6271 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 6272 p2i(r->bottom()), p2i(r->end())); 6273 _success = false; 6274 } 6275 return false; 6276 } 6277 bool success() { return _success; } 6278 }; 6279 6280 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6281 bool ret = _young_list->check_list_empty(check_sample); 6282 6283 if (check_heap) { 6284 NoYoungRegionsClosure closure; 6285 heap_region_iterate(&closure); 6286 ret = ret && closure.success(); 6287 } 6288 6289 return ret; 6290 } 6291 6292 class TearDownRegionSetsClosure : public HeapRegionClosure { 6293 private: 6294 HeapRegionSet *_old_set; 6295 6296 public: 6297 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6298 6299 bool doHeapRegion(HeapRegion* r) { 6300 if (r->is_old()) { 6301 _old_set->remove(r); 6302 } else { 6303 // We ignore free regions, we'll empty the free list afterwards. 6304 // We ignore young regions, we'll empty the young list afterwards. 6305 // We ignore humongous regions, we're not tearing down the 6306 // humongous regions set. 6307 assert(r->is_free() || r->is_young() || r->is_humongous(), 6308 "it cannot be another type"); 6309 } 6310 return false; 6311 } 6312 6313 ~TearDownRegionSetsClosure() { 6314 assert(_old_set->is_empty(), "post-condition"); 6315 } 6316 }; 6317 6318 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6319 assert_at_safepoint(true /* should_be_vm_thread */); 6320 6321 if (!free_list_only) { 6322 TearDownRegionSetsClosure cl(&_old_set); 6323 heap_region_iterate(&cl); 6324 6325 // Note that emptying the _young_list is postponed and instead done as 6326 // the first step when rebuilding the regions sets again. The reason for 6327 // this is that during a full GC string deduplication needs to know if 6328 // a collected region was young or old when the full GC was initiated. 6329 } 6330 _hrm.remove_all_free_regions(); 6331 } 6332 6333 void G1CollectedHeap::increase_used(size_t bytes) { 6334 _summary_bytes_used += bytes; 6335 } 6336 6337 void G1CollectedHeap::decrease_used(size_t bytes) { 6338 assert(_summary_bytes_used >= bytes, 6339 err_msg("invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 6340 _summary_bytes_used, bytes)); 6341 _summary_bytes_used -= bytes; 6342 } 6343 6344 void G1CollectedHeap::set_used(size_t bytes) { 6345 _summary_bytes_used = bytes; 6346 } 6347 6348 class RebuildRegionSetsClosure : public HeapRegionClosure { 6349 private: 6350 bool _free_list_only; 6351 HeapRegionSet* _old_set; 6352 HeapRegionManager* _hrm; 6353 size_t _total_used; 6354 6355 public: 6356 RebuildRegionSetsClosure(bool free_list_only, 6357 HeapRegionSet* old_set, HeapRegionManager* hrm) : 6358 _free_list_only(free_list_only), 6359 _old_set(old_set), _hrm(hrm), _total_used(0) { 6360 assert(_hrm->num_free_regions() == 0, "pre-condition"); 6361 if (!free_list_only) { 6362 assert(_old_set->is_empty(), "pre-condition"); 6363 } 6364 } 6365 6366 bool doHeapRegion(HeapRegion* r) { 6367 if (r->is_continues_humongous()) { 6368 return false; 6369 } 6370 6371 if (r->is_empty()) { 6372 // Add free regions to the free list 6373 r->set_free(); 6374 r->set_allocation_context(AllocationContext::system()); 6375 _hrm->insert_into_free_list(r); 6376 } else if (!_free_list_only) { 6377 assert(!r->is_young(), "we should not come across young regions"); 6378 6379 if (r->is_humongous()) { 6380 // We ignore humongous regions. We left the humongous set unchanged. 6381 } else { 6382 // Objects that were compacted would have ended up on regions 6383 // that were previously old or free. Archive regions (which are 6384 // old) will not have been touched. 6385 assert(r->is_free() || r->is_old(), "invariant"); 6386 // We now consider them old, so register as such. Leave 6387 // archive regions set that way, however, while still adding 6388 // them to the old set. 6389 if (!r->is_archive()) { 6390 r->set_old(); 6391 } 6392 _old_set->add(r); 6393 } 6394 _total_used += r->used(); 6395 } 6396 6397 return false; 6398 } 6399 6400 size_t total_used() { 6401 return _total_used; 6402 } 6403 }; 6404 6405 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6406 assert_at_safepoint(true /* should_be_vm_thread */); 6407 6408 if (!free_list_only) { 6409 _young_list->empty_list(); 6410 } 6411 6412 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 6413 heap_region_iterate(&cl); 6414 6415 if (!free_list_only) { 6416 set_used(cl.total_used()); 6417 if (_archive_allocator != NULL) { 6418 _archive_allocator->clear_used(); 6419 } 6420 } 6421 assert(used_unlocked() == recalculate_used(), 6422 err_msg("inconsistent used_unlocked(), " 6423 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 6424 used_unlocked(), recalculate_used())); 6425 } 6426 6427 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6428 _refine_cte_cl->set_concurrent(concurrent); 6429 } 6430 6431 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6432 HeapRegion* hr = heap_region_containing(p); 6433 return hr->is_in(p); 6434 } 6435 6436 // Methods for the mutator alloc region 6437 6438 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6439 bool force) { 6440 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6441 assert(!force || g1_policy()->can_expand_young_list(), 6442 "if force is true we should be able to expand the young list"); 6443 bool young_list_full = g1_policy()->is_young_list_full(); 6444 if (force || !young_list_full) { 6445 HeapRegion* new_alloc_region = new_region(word_size, 6446 false /* is_old */, 6447 false /* do_expand */); 6448 if (new_alloc_region != NULL) { 6449 set_region_short_lived_locked(new_alloc_region); 6450 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6451 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6452 return new_alloc_region; 6453 } 6454 } 6455 return NULL; 6456 } 6457 6458 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6459 size_t allocated_bytes) { 6460 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6461 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 6462 6463 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6464 increase_used(allocated_bytes); 6465 _hr_printer.retire(alloc_region); 6466 // We update the eden sizes here, when the region is retired, 6467 // instead of when it's allocated, since this is the point that its 6468 // used space has been recored in _summary_bytes_used. 6469 g1mm()->update_eden_size(); 6470 } 6471 6472 // Methods for the GC alloc regions 6473 6474 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6475 uint count, 6476 InCSetState dest) { 6477 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6478 6479 if (count < g1_policy()->max_regions(dest)) { 6480 const bool is_survivor = (dest.is_young()); 6481 HeapRegion* new_alloc_region = new_region(word_size, 6482 !is_survivor, 6483 true /* do_expand */); 6484 if (new_alloc_region != NULL) { 6485 // We really only need to do this for old regions given that we 6486 // should never scan survivors. But it doesn't hurt to do it 6487 // for survivors too. 6488 new_alloc_region->record_timestamp(); 6489 if (is_survivor) { 6490 new_alloc_region->set_survivor(); 6491 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6492 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6493 } else { 6494 new_alloc_region->set_old(); 6495 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6496 check_bitmaps("Old Region Allocation", new_alloc_region); 6497 } 6498 bool during_im = collector_state()->during_initial_mark_pause(); 6499 new_alloc_region->note_start_of_copying(during_im); 6500 return new_alloc_region; 6501 } 6502 } 6503 return NULL; 6504 } 6505 6506 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6507 size_t allocated_bytes, 6508 InCSetState dest) { 6509 bool during_im = collector_state()->during_initial_mark_pause(); 6510 alloc_region->note_end_of_copying(during_im); 6511 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6512 if (dest.is_young()) { 6513 young_list()->add_survivor_region(alloc_region); 6514 } else { 6515 _old_set.add(alloc_region); 6516 } 6517 _hr_printer.retire(alloc_region); 6518 } 6519 6520 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 6521 bool expanded = false; 6522 uint index = _hrm.find_highest_free(&expanded); 6523 6524 if (index != G1_NO_HRM_INDEX) { 6525 if (expanded) { 6526 ergo_verbose1(ErgoHeapSizing, 6527 "attempt heap expansion", 6528 ergo_format_reason("requested address range outside heap bounds") 6529 ergo_format_byte("region size"), 6530 HeapRegion::GrainWords * HeapWordSize); 6531 } 6532 _hrm.allocate_free_regions_starting_at(index, 1); 6533 return region_at(index); 6534 } 6535 return NULL; 6536 } 6537 6538 // Heap region set verification 6539 6540 class VerifyRegionListsClosure : public HeapRegionClosure { 6541 private: 6542 HeapRegionSet* _old_set; 6543 HeapRegionSet* _humongous_set; 6544 HeapRegionManager* _hrm; 6545 6546 public: 6547 HeapRegionSetCount _old_count; 6548 HeapRegionSetCount _humongous_count; 6549 HeapRegionSetCount _free_count; 6550 6551 VerifyRegionListsClosure(HeapRegionSet* old_set, 6552 HeapRegionSet* humongous_set, 6553 HeapRegionManager* hrm) : 6554 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm), 6555 _old_count(), _humongous_count(), _free_count(){ } 6556 6557 bool doHeapRegion(HeapRegion* hr) { 6558 if (hr->is_continues_humongous()) { 6559 return false; 6560 } 6561 6562 if (hr->is_young()) { 6563 // TODO 6564 } else if (hr->is_starts_humongous()) { 6565 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index())); 6566 _humongous_count.increment(1u, hr->capacity()); 6567 } else if (hr->is_empty()) { 6568 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index())); 6569 _free_count.increment(1u, hr->capacity()); 6570 } else if (hr->is_old()) { 6571 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index())); 6572 _old_count.increment(1u, hr->capacity()); 6573 } else { 6574 // There are no other valid region types. Check for one invalid 6575 // one we can identify: pinned without old or humongous set. 6576 assert(!hr->is_pinned(), err_msg("Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index())); 6577 ShouldNotReachHere(); 6578 } 6579 return false; 6580 } 6581 6582 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) { 6583 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 6584 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6585 old_set->total_capacity_bytes(), _old_count.capacity())); 6586 6587 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 6588 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6589 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 6590 6591 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())); 6592 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6593 free_list->total_capacity_bytes(), _free_count.capacity())); 6594 } 6595 }; 6596 6597 void G1CollectedHeap::verify_region_sets() { 6598 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6599 6600 // First, check the explicit lists. 6601 _hrm.verify(); 6602 { 6603 // Given that a concurrent operation might be adding regions to 6604 // the secondary free list we have to take the lock before 6605 // verifying it. 6606 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6607 _secondary_free_list.verify_list(); 6608 } 6609 6610 // If a concurrent region freeing operation is in progress it will 6611 // be difficult to correctly attributed any free regions we come 6612 // across to the correct free list given that they might belong to 6613 // one of several (free_list, secondary_free_list, any local lists, 6614 // etc.). So, if that's the case we will skip the rest of the 6615 // verification operation. Alternatively, waiting for the concurrent 6616 // operation to complete will have a non-trivial effect on the GC's 6617 // operation (no concurrent operation will last longer than the 6618 // interval between two calls to verification) and it might hide 6619 // any issues that we would like to catch during testing. 6620 if (free_regions_coming()) { 6621 return; 6622 } 6623 6624 // Make sure we append the secondary_free_list on the free_list so 6625 // that all free regions we will come across can be safely 6626 // attributed to the free_list. 6627 append_secondary_free_list_if_not_empty_with_lock(); 6628 6629 // Finally, make sure that the region accounting in the lists is 6630 // consistent with what we see in the heap. 6631 6632 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm); 6633 heap_region_iterate(&cl); 6634 cl.verify_counts(&_old_set, &_humongous_set, &_hrm); 6635 } 6636 6637 // Optimized nmethod scanning 6638 6639 class RegisterNMethodOopClosure: public OopClosure { 6640 G1CollectedHeap* _g1h; 6641 nmethod* _nm; 6642 6643 template <class T> void do_oop_work(T* p) { 6644 T heap_oop = oopDesc::load_heap_oop(p); 6645 if (!oopDesc::is_null(heap_oop)) { 6646 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6647 HeapRegion* hr = _g1h->heap_region_containing(obj); 6648 assert(!hr->is_continues_humongous(), 6649 err_msg("trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 6650 " starting at " HR_FORMAT, 6651 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6652 6653 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 6654 hr->add_strong_code_root_locked(_nm); 6655 } 6656 } 6657 6658 public: 6659 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6660 _g1h(g1h), _nm(nm) {} 6661 6662 void do_oop(oop* p) { do_oop_work(p); } 6663 void do_oop(narrowOop* p) { do_oop_work(p); } 6664 }; 6665 6666 class UnregisterNMethodOopClosure: public OopClosure { 6667 G1CollectedHeap* _g1h; 6668 nmethod* _nm; 6669 6670 template <class T> void do_oop_work(T* p) { 6671 T heap_oop = oopDesc::load_heap_oop(p); 6672 if (!oopDesc::is_null(heap_oop)) { 6673 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6674 HeapRegion* hr = _g1h->heap_region_containing(obj); 6675 assert(!hr->is_continues_humongous(), 6676 err_msg("trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 6677 " starting at " HR_FORMAT, 6678 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6679 6680 hr->remove_strong_code_root(_nm); 6681 } 6682 } 6683 6684 public: 6685 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6686 _g1h(g1h), _nm(nm) {} 6687 6688 void do_oop(oop* p) { do_oop_work(p); } 6689 void do_oop(narrowOop* p) { do_oop_work(p); } 6690 }; 6691 6692 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6693 CollectedHeap::register_nmethod(nm); 6694 6695 guarantee(nm != NULL, "sanity"); 6696 RegisterNMethodOopClosure reg_cl(this, nm); 6697 nm->oops_do(®_cl); 6698 } 6699 6700 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6701 CollectedHeap::unregister_nmethod(nm); 6702 6703 guarantee(nm != NULL, "sanity"); 6704 UnregisterNMethodOopClosure reg_cl(this, nm); 6705 nm->oops_do(®_cl, true); 6706 } 6707 6708 void G1CollectedHeap::purge_code_root_memory() { 6709 double purge_start = os::elapsedTime(); 6710 G1CodeRootSet::purge(); 6711 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6712 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6713 } 6714 6715 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6716 G1CollectedHeap* _g1h; 6717 6718 public: 6719 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6720 _g1h(g1h) {} 6721 6722 void do_code_blob(CodeBlob* cb) { 6723 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6724 if (nm == NULL) { 6725 return; 6726 } 6727 6728 if (ScavengeRootsInCode) { 6729 _g1h->register_nmethod(nm); 6730 } 6731 } 6732 }; 6733 6734 void G1CollectedHeap::rebuild_strong_code_roots() { 6735 RebuildStrongCodeRootClosure blob_cl(this); 6736 CodeCache::blobs_do(&blob_cl); 6737 }