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_implementation/g1/bufferingOopClosure.hpp" 31 #include "gc_implementation/g1/concurrentG1Refine.hpp" 32 #include "gc_implementation/g1/concurrentG1RefineThread.hpp" 33 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 34 #include "gc_implementation/g1/g1AllocRegion.inline.hpp" 35 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 36 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 37 #include "gc_implementation/g1/g1CollectorState.hpp" 38 #include "gc_implementation/g1/g1ErgoVerbose.hpp" 39 #include "gc_implementation/g1/g1EvacFailure.hpp" 40 #include "gc_implementation/g1/g1GCPhaseTimes.hpp" 41 #include "gc_implementation/g1/g1Log.hpp" 42 #include "gc_implementation/g1/g1MarkSweep.hpp" 43 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 44 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp" 45 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp" 46 #include "gc_implementation/g1/g1RemSet.inline.hpp" 47 #include "gc_implementation/g1/g1RootProcessor.hpp" 48 #include "gc_implementation/g1/g1StringDedup.hpp" 49 #include "gc_implementation/g1/g1YCTypes.hpp" 50 #include "gc_implementation/g1/heapRegion.inline.hpp" 51 #include "gc_implementation/g1/heapRegionRemSet.hpp" 52 #include "gc_implementation/g1/heapRegionSet.inline.hpp" 53 #include "gc_implementation/g1/vm_operations_g1.hpp" 54 #include "gc_implementation/shared/gcHeapSummary.hpp" 55 #include "gc_implementation/shared/gcTimer.hpp" 56 #include "gc_implementation/shared/gcTrace.hpp" 57 #include "gc_implementation/shared/gcTraceTime.hpp" 58 #include "gc_implementation/shared/isGCActiveMark.hpp" 59 #include "memory/allocation.hpp" 60 #include "memory/gcLocker.inline.hpp" 61 #include "memory/generationSpec.hpp" 62 #include "memory/iterator.hpp" 63 #include "memory/referenceProcessor.hpp" 64 #include "oops/oop.inline.hpp" 65 #include "runtime/atomic.inline.hpp" 66 #include "runtime/orderAccess.inline.hpp" 67 #include "runtime/vmThread.hpp" 68 #include "utilities/globalDefinitions.hpp" 69 #include "utilities/stack.inline.hpp" 70 #include "utilities/taskqueue.inline.hpp" 71 72 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 73 74 // turn it on so that the contents of the young list (scan-only / 75 // to-be-collected) are printed at "strategic" points before / during 76 // / after the collection --- this is useful for debugging 77 #define YOUNG_LIST_VERBOSE 0 78 // CURRENT STATUS 79 // This file is under construction. Search for "FIXME". 80 81 // INVARIANTS/NOTES 82 // 83 // All allocation activity covered by the G1CollectedHeap interface is 84 // serialized by acquiring the HeapLock. This happens in mem_allocate 85 // and allocate_new_tlab, which are the "entry" points to the 86 // allocation code from the rest of the JVM. (Note that this does not 87 // apply to TLAB allocation, which is not part of this interface: it 88 // is done by clients of this interface.) 89 90 // Local to this file. 91 92 class RefineCardTableEntryClosure: public CardTableEntryClosure { 93 bool _concurrent; 94 public: 95 RefineCardTableEntryClosure() : _concurrent(true) { } 96 97 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 98 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 99 // This path is executed by the concurrent refine or mutator threads, 100 // concurrently, and so we do not care if card_ptr contains references 101 // that point into the collection set. 102 assert(!oops_into_cset, "should be"); 103 104 if (_concurrent && SuspendibleThreadSet::should_yield()) { 105 // Caller will actually yield. 106 return false; 107 } 108 // Otherwise, we finished successfully; return true. 109 return true; 110 } 111 112 void set_concurrent(bool b) { _concurrent = b; } 113 }; 114 115 116 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 117 private: 118 size_t _num_processed; 119 120 public: 121 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { } 122 123 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 124 *card_ptr = CardTableModRefBS::dirty_card_val(); 125 _num_processed++; 126 return true; 127 } 128 129 size_t num_processed() const { return _num_processed; } 130 }; 131 132 YoungList::YoungList(G1CollectedHeap* g1h) : 133 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 134 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 135 guarantee(check_list_empty(false), "just making sure..."); 136 } 137 138 void YoungList::push_region(HeapRegion *hr) { 139 assert(!hr->is_young(), "should not already be young"); 140 assert(hr->get_next_young_region() == NULL, "cause it should!"); 141 142 hr->set_next_young_region(_head); 143 _head = hr; 144 145 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 146 ++_length; 147 } 148 149 void YoungList::add_survivor_region(HeapRegion* hr) { 150 assert(hr->is_survivor(), "should be flagged as survivor region"); 151 assert(hr->get_next_young_region() == NULL, "cause it should!"); 152 153 hr->set_next_young_region(_survivor_head); 154 if (_survivor_head == NULL) { 155 _survivor_tail = hr; 156 } 157 _survivor_head = hr; 158 ++_survivor_length; 159 } 160 161 void YoungList::empty_list(HeapRegion* list) { 162 while (list != NULL) { 163 HeapRegion* next = list->get_next_young_region(); 164 list->set_next_young_region(NULL); 165 list->uninstall_surv_rate_group(); 166 // This is called before a Full GC and all the non-empty / 167 // non-humongous regions at the end of the Full GC will end up as 168 // old anyway. 169 list->set_old(); 170 list = next; 171 } 172 } 173 174 void YoungList::empty_list() { 175 assert(check_list_well_formed(), "young list should be well formed"); 176 177 empty_list(_head); 178 _head = NULL; 179 _length = 0; 180 181 empty_list(_survivor_head); 182 _survivor_head = NULL; 183 _survivor_tail = NULL; 184 _survivor_length = 0; 185 186 _last_sampled_rs_lengths = 0; 187 188 assert(check_list_empty(false), "just making sure..."); 189 } 190 191 bool YoungList::check_list_well_formed() { 192 bool ret = true; 193 194 uint length = 0; 195 HeapRegion* curr = _head; 196 HeapRegion* last = NULL; 197 while (curr != NULL) { 198 if (!curr->is_young()) { 199 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " 200 "incorrectly tagged (y: %d, surv: %d)", 201 p2i(curr->bottom()), p2i(curr->end()), 202 curr->is_young(), curr->is_survivor()); 203 ret = false; 204 } 205 ++length; 206 last = curr; 207 curr = curr->get_next_young_region(); 208 } 209 ret = ret && (length == _length); 210 211 if (!ret) { 212 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 213 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 214 length, _length); 215 } 216 217 return ret; 218 } 219 220 bool YoungList::check_list_empty(bool check_sample) { 221 bool ret = true; 222 223 if (_length != 0) { 224 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 225 _length); 226 ret = false; 227 } 228 if (check_sample && _last_sampled_rs_lengths != 0) { 229 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 230 ret = false; 231 } 232 if (_head != NULL) { 233 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 234 ret = false; 235 } 236 if (!ret) { 237 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 238 } 239 240 return ret; 241 } 242 243 void 244 YoungList::rs_length_sampling_init() { 245 _sampled_rs_lengths = 0; 246 _curr = _head; 247 } 248 249 bool 250 YoungList::rs_length_sampling_more() { 251 return _curr != NULL; 252 } 253 254 void 255 YoungList::rs_length_sampling_next() { 256 assert( _curr != NULL, "invariant" ); 257 size_t rs_length = _curr->rem_set()->occupied(); 258 259 _sampled_rs_lengths += rs_length; 260 261 // The current region may not yet have been added to the 262 // incremental collection set (it gets added when it is 263 // retired as the current allocation region). 264 if (_curr->in_collection_set()) { 265 // Update the collection set policy information for this region 266 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 267 } 268 269 _curr = _curr->get_next_young_region(); 270 if (_curr == NULL) { 271 _last_sampled_rs_lengths = _sampled_rs_lengths; 272 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 273 } 274 } 275 276 void 277 YoungList::reset_auxilary_lists() { 278 guarantee( is_empty(), "young list should be empty" ); 279 assert(check_list_well_formed(), "young list should be well formed"); 280 281 // Add survivor regions to SurvRateGroup. 282 _g1h->g1_policy()->note_start_adding_survivor_regions(); 283 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 284 285 int young_index_in_cset = 0; 286 for (HeapRegion* curr = _survivor_head; 287 curr != NULL; 288 curr = curr->get_next_young_region()) { 289 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 290 291 // The region is a non-empty survivor so let's add it to 292 // the incremental collection set for the next evacuation 293 // pause. 294 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 295 young_index_in_cset += 1; 296 } 297 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 298 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 299 300 _head = _survivor_head; 301 _length = _survivor_length; 302 if (_survivor_head != NULL) { 303 assert(_survivor_tail != NULL, "cause it shouldn't be"); 304 assert(_survivor_length > 0, "invariant"); 305 _survivor_tail->set_next_young_region(NULL); 306 } 307 308 // Don't clear the survivor list handles until the start of 309 // the next evacuation pause - we need it in order to re-tag 310 // the survivor regions from this evacuation pause as 'young' 311 // at the start of the next. 312 313 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 314 315 assert(check_list_well_formed(), "young list should be well formed"); 316 } 317 318 void YoungList::print() { 319 HeapRegion* lists[] = {_head, _survivor_head}; 320 const char* names[] = {"YOUNG", "SURVIVOR"}; 321 322 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) { 323 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 324 HeapRegion *curr = lists[list]; 325 if (curr == NULL) 326 gclog_or_tty->print_cr(" empty"); 327 while (curr != NULL) { 328 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d", 329 HR_FORMAT_PARAMS(curr), 330 p2i(curr->prev_top_at_mark_start()), 331 p2i(curr->next_top_at_mark_start()), 332 curr->age_in_surv_rate_group_cond()); 333 curr = curr->get_next_young_region(); 334 } 335 } 336 337 gclog_or_tty->cr(); 338 } 339 340 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 341 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 342 } 343 344 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 345 // The from card cache is not the memory that is actually committed. So we cannot 346 // take advantage of the zero_filled parameter. 347 reset_from_card_cache(start_idx, num_regions); 348 } 349 350 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 351 { 352 // Claim the right to put the region on the dirty cards region list 353 // by installing a self pointer. 354 HeapRegion* next = hr->get_next_dirty_cards_region(); 355 if (next == NULL) { 356 HeapRegion* res = (HeapRegion*) 357 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 358 NULL); 359 if (res == NULL) { 360 HeapRegion* head; 361 do { 362 // Put the region to the dirty cards region list. 363 head = _dirty_cards_region_list; 364 next = (HeapRegion*) 365 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 366 if (next == head) { 367 assert(hr->get_next_dirty_cards_region() == hr, 368 "hr->get_next_dirty_cards_region() != hr"); 369 if (next == NULL) { 370 // The last region in the list points to itself. 371 hr->set_next_dirty_cards_region(hr); 372 } else { 373 hr->set_next_dirty_cards_region(next); 374 } 375 } 376 } while (next != head); 377 } 378 } 379 } 380 381 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 382 { 383 HeapRegion* head; 384 HeapRegion* hr; 385 do { 386 head = _dirty_cards_region_list; 387 if (head == NULL) { 388 return NULL; 389 } 390 HeapRegion* new_head = head->get_next_dirty_cards_region(); 391 if (head == new_head) { 392 // The last region. 393 new_head = NULL; 394 } 395 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 396 head); 397 } while (hr != head); 398 assert(hr != NULL, "invariant"); 399 hr->set_next_dirty_cards_region(NULL); 400 return hr; 401 } 402 403 // Returns true if the reference points to an object that 404 // can move in an incremental collection. 405 bool G1CollectedHeap::is_scavengable(const void* p) { 406 HeapRegion* hr = heap_region_containing(p); 407 return !hr->is_humongous(); 408 } 409 410 // Private methods. 411 412 HeapRegion* 413 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 414 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 415 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 416 if (!_secondary_free_list.is_empty()) { 417 if (G1ConcRegionFreeingVerbose) { 418 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 419 "secondary_free_list has %u entries", 420 _secondary_free_list.length()); 421 } 422 // It looks as if there are free regions available on the 423 // secondary_free_list. Let's move them to the free_list and try 424 // again to allocate from it. 425 append_secondary_free_list(); 426 427 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 428 "empty we should have moved at least one entry to the free_list"); 429 HeapRegion* res = _hrm.allocate_free_region(is_old); 430 if (G1ConcRegionFreeingVerbose) { 431 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 432 "allocated "HR_FORMAT" from secondary_free_list", 433 HR_FORMAT_PARAMS(res)); 434 } 435 return res; 436 } 437 438 // Wait here until we get notified either when (a) there are no 439 // more free regions coming or (b) some regions have been moved on 440 // the secondary_free_list. 441 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 442 } 443 444 if (G1ConcRegionFreeingVerbose) { 445 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 446 "could not allocate from secondary_free_list"); 447 } 448 return NULL; 449 } 450 451 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 452 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 453 "the only time we use this to allocate a humongous region is " 454 "when we are allocating a single humongous region"); 455 456 HeapRegion* res; 457 if (G1StressConcRegionFreeing) { 458 if (!_secondary_free_list.is_empty()) { 459 if (G1ConcRegionFreeingVerbose) { 460 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 461 "forced to look at the secondary_free_list"); 462 } 463 res = new_region_try_secondary_free_list(is_old); 464 if (res != NULL) { 465 return res; 466 } 467 } 468 } 469 470 res = _hrm.allocate_free_region(is_old); 471 472 if (res == NULL) { 473 if (G1ConcRegionFreeingVerbose) { 474 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 475 "res == NULL, trying the secondary_free_list"); 476 } 477 res = new_region_try_secondary_free_list(is_old); 478 } 479 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 480 // Currently, only attempts to allocate GC alloc regions set 481 // do_expand to true. So, we should only reach here during a 482 // safepoint. If this assumption changes we might have to 483 // reconsider the use of _expand_heap_after_alloc_failure. 484 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 485 486 ergo_verbose1(ErgoHeapSizing, 487 "attempt heap expansion", 488 ergo_format_reason("region allocation request failed") 489 ergo_format_byte("allocation request"), 490 word_size * HeapWordSize); 491 if (expand(word_size * HeapWordSize)) { 492 // Given that expand() succeeded in expanding the heap, and we 493 // always expand the heap by an amount aligned to the heap 494 // region size, the free list should in theory not be empty. 495 // In either case allocate_free_region() will check for NULL. 496 res = _hrm.allocate_free_region(is_old); 497 } else { 498 _expand_heap_after_alloc_failure = false; 499 } 500 } 501 return res; 502 } 503 504 HeapWord* 505 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 506 uint num_regions, 507 size_t word_size, 508 AllocationContext_t context) { 509 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 510 assert(is_humongous(word_size), "word_size should be humongous"); 511 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 512 513 // Index of last region in the series + 1. 514 uint last = first + num_regions; 515 516 // We need to initialize the region(s) we just discovered. This is 517 // a bit tricky given that it can happen concurrently with 518 // refinement threads refining cards on these regions and 519 // potentially wanting to refine the BOT as they are scanning 520 // those cards (this can happen shortly after a cleanup; see CR 521 // 6991377). So we have to set up the region(s) carefully and in 522 // a specific order. 523 524 // The word size sum of all the regions we will allocate. 525 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 526 assert(word_size <= word_size_sum, "sanity"); 527 528 // This will be the "starts humongous" region. 529 HeapRegion* first_hr = region_at(first); 530 // The header of the new object will be placed at the bottom of 531 // the first region. 532 HeapWord* new_obj = first_hr->bottom(); 533 // This will be the new end of the first region in the series that 534 // should also match the end of the last region in the series. 535 HeapWord* new_end = new_obj + word_size_sum; 536 // This will be the new top of the first region that will reflect 537 // this allocation. 538 HeapWord* new_top = new_obj + word_size; 539 540 // First, we need to zero the header of the space that we will be 541 // allocating. When we update top further down, some refinement 542 // threads might try to scan the region. By zeroing the header we 543 // ensure that any thread that will try to scan the region will 544 // come across the zero klass word and bail out. 545 // 546 // NOTE: It would not have been correct to have used 547 // CollectedHeap::fill_with_object() and make the space look like 548 // an int array. The thread that is doing the allocation will 549 // later update the object header to a potentially different array 550 // type and, for a very short period of time, the klass and length 551 // fields will be inconsistent. This could cause a refinement 552 // thread to calculate the object size incorrectly. 553 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 554 555 // We will set up the first region as "starts humongous". This 556 // will also update the BOT covering all the regions to reflect 557 // that there is a single object that starts at the bottom of the 558 // first region. 559 first_hr->set_starts_humongous(new_top, new_end); 560 first_hr->set_allocation_context(context); 561 // Then, if there are any, we will set up the "continues 562 // humongous" regions. 563 HeapRegion* hr = NULL; 564 for (uint i = first + 1; i < last; ++i) { 565 hr = region_at(i); 566 hr->set_continues_humongous(first_hr); 567 hr->set_allocation_context(context); 568 } 569 // If we have "continues humongous" regions (hr != NULL), then the 570 // end of the last one should match new_end. 571 assert(hr == NULL || hr->end() == new_end, "sanity"); 572 573 // Up to this point no concurrent thread would have been able to 574 // do any scanning on any region in this series. All the top 575 // fields still point to bottom, so the intersection between 576 // [bottom,top] and [card_start,card_end] will be empty. Before we 577 // update the top fields, we'll do a storestore to make sure that 578 // no thread sees the update to top before the zeroing of the 579 // object header and the BOT initialization. 580 OrderAccess::storestore(); 581 582 // Now that the BOT and the object header have been initialized, 583 // we can update top of the "starts humongous" region. 584 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 585 "new_top should be in this region"); 586 first_hr->set_top(new_top); 587 if (_hr_printer.is_active()) { 588 HeapWord* bottom = first_hr->bottom(); 589 HeapWord* end = first_hr->orig_end(); 590 if ((first + 1) == last) { 591 // the series has a single humongous region 592 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 593 } else { 594 // the series has more than one humongous regions 595 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 596 } 597 } 598 599 // Now, we will update the top fields of the "continues humongous" 600 // regions. The reason we need to do this is that, otherwise, 601 // these regions would look empty and this will confuse parts of 602 // G1. For example, the code that looks for a consecutive number 603 // of empty regions will consider them empty and try to 604 // re-allocate them. We can extend is_empty() to also include 605 // !is_continues_humongous(), but it is easier to just update the top 606 // fields here. The way we set top for all regions (i.e., top == 607 // end for all regions but the last one, top == new_top for the 608 // last one) is actually used when we will free up the humongous 609 // region in free_humongous_region(). 610 hr = NULL; 611 for (uint i = first + 1; i < last; ++i) { 612 hr = region_at(i); 613 if ((i + 1) == last) { 614 // last continues humongous region 615 assert(hr->bottom() < new_top && new_top <= hr->end(), 616 "new_top should fall on this region"); 617 hr->set_top(new_top); 618 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 619 } else { 620 // not last one 621 assert(new_top > hr->end(), "new_top should be above this region"); 622 hr->set_top(hr->end()); 623 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 624 } 625 } 626 // If we have continues humongous regions (hr != NULL), then the 627 // end of the last one should match new_end and its top should 628 // match new_top. 629 assert(hr == NULL || 630 (hr->end() == new_end && hr->top() == new_top), "sanity"); 631 check_bitmaps("Humongous Region Allocation", first_hr); 632 633 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 634 _allocator->increase_used(first_hr->used()); 635 _humongous_set.add(first_hr); 636 637 return new_obj; 638 } 639 640 // If could fit into free regions w/o expansion, try. 641 // Otherwise, if can expand, do so. 642 // Otherwise, if using ex regions might help, try with ex given back. 643 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 644 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 645 646 verify_region_sets_optional(); 647 648 uint first = G1_NO_HRM_INDEX; 649 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords); 650 651 if (obj_regions == 1) { 652 // Only one region to allocate, try to use a fast path by directly allocating 653 // from the free lists. Do not try to expand here, we will potentially do that 654 // later. 655 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 656 if (hr != NULL) { 657 first = hr->hrm_index(); 658 } 659 } else { 660 // We can't allocate humongous regions spanning more than one region while 661 // cleanupComplete() is running, since some of the regions we find to be 662 // empty might not yet be added to the free list. It is not straightforward 663 // to know in which list they are on so that we can remove them. We only 664 // need to do this if we need to allocate more than one region to satisfy the 665 // current humongous allocation request. If we are only allocating one region 666 // we use the one-region region allocation code (see above), that already 667 // potentially waits for regions from the secondary free list. 668 wait_while_free_regions_coming(); 669 append_secondary_free_list_if_not_empty_with_lock(); 670 671 // Policy: Try only empty regions (i.e. already committed first). Maybe we 672 // are lucky enough to find some. 673 first = _hrm.find_contiguous_only_empty(obj_regions); 674 if (first != G1_NO_HRM_INDEX) { 675 _hrm.allocate_free_regions_starting_at(first, obj_regions); 676 } 677 } 678 679 if (first == G1_NO_HRM_INDEX) { 680 // Policy: We could not find enough regions for the humongous object in the 681 // free list. Look through the heap to find a mix of free and uncommitted regions. 682 // If so, try expansion. 683 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 684 if (first != G1_NO_HRM_INDEX) { 685 // We found something. Make sure these regions are committed, i.e. expand 686 // the heap. Alternatively we could do a defragmentation GC. 687 ergo_verbose1(ErgoHeapSizing, 688 "attempt heap expansion", 689 ergo_format_reason("humongous allocation request failed") 690 ergo_format_byte("allocation request"), 691 word_size * HeapWordSize); 692 693 _hrm.expand_at(first, obj_regions); 694 g1_policy()->record_new_heap_size(num_regions()); 695 696 #ifdef ASSERT 697 for (uint i = first; i < first + obj_regions; ++i) { 698 HeapRegion* hr = region_at(i); 699 assert(hr->is_free(), "sanity"); 700 assert(hr->is_empty(), "sanity"); 701 assert(is_on_master_free_list(hr), "sanity"); 702 } 703 #endif 704 _hrm.allocate_free_regions_starting_at(first, obj_regions); 705 } else { 706 // Policy: Potentially trigger a defragmentation GC. 707 } 708 } 709 710 HeapWord* result = NULL; 711 if (first != G1_NO_HRM_INDEX) { 712 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 713 word_size, context); 714 assert(result != NULL, "it should always return a valid result"); 715 716 // A successful humongous object allocation changes the used space 717 // information of the old generation so we need to recalculate the 718 // sizes and update the jstat counters here. 719 g1mm()->update_sizes(); 720 } 721 722 verify_region_sets_optional(); 723 724 return result; 725 } 726 727 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 728 assert_heap_not_locked_and_not_at_safepoint(); 729 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 730 731 uint dummy_gc_count_before; 732 uint dummy_gclocker_retry_count = 0; 733 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 734 } 735 736 HeapWord* 737 G1CollectedHeap::mem_allocate(size_t word_size, 738 bool* gc_overhead_limit_was_exceeded) { 739 assert_heap_not_locked_and_not_at_safepoint(); 740 741 // Loop until the allocation is satisfied, or unsatisfied after GC. 742 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 743 uint gc_count_before; 744 745 HeapWord* result = NULL; 746 if (!is_humongous(word_size)) { 747 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 748 } else { 749 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 750 } 751 if (result != NULL) { 752 return result; 753 } 754 755 // Create the garbage collection operation... 756 VM_G1CollectForAllocation op(gc_count_before, word_size); 757 op.set_allocation_context(AllocationContext::current()); 758 759 // ...and get the VM thread to execute it. 760 VMThread::execute(&op); 761 762 if (op.prologue_succeeded() && op.pause_succeeded()) { 763 // If the operation was successful we'll return the result even 764 // if it is NULL. If the allocation attempt failed immediately 765 // after a Full GC, it's unlikely we'll be able to allocate now. 766 HeapWord* result = op.result(); 767 if (result != NULL && !is_humongous(word_size)) { 768 // Allocations that take place on VM operations do not do any 769 // card dirtying and we have to do it here. We only have to do 770 // this for non-humongous allocations, though. 771 dirty_young_block(result, word_size); 772 } 773 return result; 774 } else { 775 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 776 return NULL; 777 } 778 assert(op.result() == NULL, 779 "the result should be NULL if the VM op did not succeed"); 780 } 781 782 // Give a warning if we seem to be looping forever. 783 if ((QueuedAllocationWarningCount > 0) && 784 (try_count % QueuedAllocationWarningCount == 0)) { 785 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 786 } 787 } 788 789 ShouldNotReachHere(); 790 return NULL; 791 } 792 793 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 794 AllocationContext_t context, 795 uint* gc_count_before_ret, 796 uint* gclocker_retry_count_ret) { 797 // Make sure you read the note in attempt_allocation_humongous(). 798 799 assert_heap_not_locked_and_not_at_safepoint(); 800 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 801 "be called for humongous allocation requests"); 802 803 // We should only get here after the first-level allocation attempt 804 // (attempt_allocation()) failed to allocate. 805 806 // We will loop until a) we manage to successfully perform the 807 // allocation or b) we successfully schedule a collection which 808 // fails to perform the allocation. b) is the only case when we'll 809 // return NULL. 810 HeapWord* result = NULL; 811 for (int try_count = 1; /* we'll return */; try_count += 1) { 812 bool should_try_gc; 813 uint gc_count_before; 814 815 { 816 MutexLockerEx x(Heap_lock); 817 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, 818 false /* bot_updates */); 819 if (result != NULL) { 820 return result; 821 } 822 823 // If we reach here, attempt_allocation_locked() above failed to 824 // allocate a new region. So the mutator alloc region should be NULL. 825 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here"); 826 827 if (GC_locker::is_active_and_needs_gc()) { 828 if (g1_policy()->can_expand_young_list()) { 829 // No need for an ergo verbose message here, 830 // can_expand_young_list() does this when it returns true. 831 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size, 832 false /* bot_updates */); 833 if (result != NULL) { 834 return result; 835 } 836 } 837 should_try_gc = false; 838 } else { 839 // The GCLocker may not be active but the GCLocker initiated 840 // GC may not yet have been performed (GCLocker::needs_gc() 841 // returns true). In this case we do not try this GC and 842 // wait until the GCLocker initiated GC is performed, and 843 // then retry the allocation. 844 if (GC_locker::needs_gc()) { 845 should_try_gc = false; 846 } else { 847 // Read the GC count while still holding the Heap_lock. 848 gc_count_before = total_collections(); 849 should_try_gc = true; 850 } 851 } 852 } 853 854 if (should_try_gc) { 855 bool succeeded; 856 result = do_collection_pause(word_size, gc_count_before, &succeeded, 857 GCCause::_g1_inc_collection_pause); 858 if (result != NULL) { 859 assert(succeeded, "only way to get back a non-NULL result"); 860 return result; 861 } 862 863 if (succeeded) { 864 // If we get here we successfully scheduled a collection which 865 // failed to allocate. No point in trying to allocate 866 // further. We'll just return NULL. 867 MutexLockerEx x(Heap_lock); 868 *gc_count_before_ret = total_collections(); 869 return NULL; 870 } 871 } else { 872 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 873 MutexLockerEx x(Heap_lock); 874 *gc_count_before_ret = total_collections(); 875 return NULL; 876 } 877 // The GCLocker is either active or the GCLocker initiated 878 // GC has not yet been performed. Stall until it is and 879 // then retry the allocation. 880 GC_locker::stall_until_clear(); 881 (*gclocker_retry_count_ret) += 1; 882 } 883 884 // We can reach here if we were unsuccessful in scheduling a 885 // collection (because another thread beat us to it) or if we were 886 // stalled due to the GC locker. In either can we should retry the 887 // allocation attempt in case another thread successfully 888 // performed a collection and reclaimed enough space. We do the 889 // first attempt (without holding the Heap_lock) here and the 890 // follow-on attempt will be at the start of the next loop 891 // iteration (after taking the Heap_lock). 892 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size, 893 false /* bot_updates */); 894 if (result != NULL) { 895 return result; 896 } 897 898 // Give a warning if we seem to be looping forever. 899 if ((QueuedAllocationWarningCount > 0) && 900 (try_count % QueuedAllocationWarningCount == 0)) { 901 warning("G1CollectedHeap::attempt_allocation_slow() " 902 "retries %d times", try_count); 903 } 904 } 905 906 ShouldNotReachHere(); 907 return NULL; 908 } 909 910 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 911 uint* gc_count_before_ret, 912 uint* gclocker_retry_count_ret) { 913 // The structure of this method has a lot of similarities to 914 // attempt_allocation_slow(). The reason these two were not merged 915 // into a single one is that such a method would require several "if 916 // allocation is not humongous do this, otherwise do that" 917 // conditional paths which would obscure its flow. In fact, an early 918 // version of this code did use a unified method which was harder to 919 // follow and, as a result, it had subtle bugs that were hard to 920 // track down. So keeping these two methods separate allows each to 921 // be more readable. It will be good to keep these two in sync as 922 // much as possible. 923 924 assert_heap_not_locked_and_not_at_safepoint(); 925 assert(is_humongous(word_size), "attempt_allocation_humongous() " 926 "should only be called for humongous allocations"); 927 928 // Humongous objects can exhaust the heap quickly, so we should check if we 929 // need to start a marking cycle at each humongous object allocation. We do 930 // the check before we do the actual allocation. The reason for doing it 931 // before the allocation is that we avoid having to keep track of the newly 932 // allocated memory while we do a GC. 933 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 934 word_size)) { 935 collect(GCCause::_g1_humongous_allocation); 936 } 937 938 // We will loop until a) we manage to successfully perform the 939 // allocation or b) we successfully schedule a collection which 940 // fails to perform the allocation. b) is the only case when we'll 941 // return NULL. 942 HeapWord* result = NULL; 943 for (int try_count = 1; /* we'll return */; try_count += 1) { 944 bool should_try_gc; 945 uint gc_count_before; 946 947 { 948 MutexLockerEx x(Heap_lock); 949 950 // Given that humongous objects are not allocated in young 951 // regions, we'll first try to do the allocation without doing a 952 // collection hoping that there's enough space in the heap. 953 result = humongous_obj_allocate(word_size, AllocationContext::current()); 954 if (result != NULL) { 955 return result; 956 } 957 958 if (GC_locker::is_active_and_needs_gc()) { 959 should_try_gc = false; 960 } else { 961 // The GCLocker may not be active but the GCLocker initiated 962 // GC may not yet have been performed (GCLocker::needs_gc() 963 // returns true). In this case we do not try this GC and 964 // wait until the GCLocker initiated GC is performed, and 965 // then retry the allocation. 966 if (GC_locker::needs_gc()) { 967 should_try_gc = false; 968 } else { 969 // Read the GC count while still holding the Heap_lock. 970 gc_count_before = total_collections(); 971 should_try_gc = true; 972 } 973 } 974 } 975 976 if (should_try_gc) { 977 // If we failed to allocate the humongous object, we should try to 978 // do a collection pause (if we're allowed) in case it reclaims 979 // enough space for the allocation to succeed after the pause. 980 981 bool succeeded; 982 result = do_collection_pause(word_size, gc_count_before, &succeeded, 983 GCCause::_g1_humongous_allocation); 984 if (result != NULL) { 985 assert(succeeded, "only way to get back a non-NULL result"); 986 return result; 987 } 988 989 if (succeeded) { 990 // If we get here we successfully scheduled a collection which 991 // failed to allocate. No point in trying to allocate 992 // further. We'll just return NULL. 993 MutexLockerEx x(Heap_lock); 994 *gc_count_before_ret = total_collections(); 995 return NULL; 996 } 997 } else { 998 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 999 MutexLockerEx x(Heap_lock); 1000 *gc_count_before_ret = total_collections(); 1001 return NULL; 1002 } 1003 // The GCLocker is either active or the GCLocker initiated 1004 // GC has not yet been performed. Stall until it is and 1005 // then retry the allocation. 1006 GC_locker::stall_until_clear(); 1007 (*gclocker_retry_count_ret) += 1; 1008 } 1009 1010 // We can reach here if we were unsuccessful in scheduling a 1011 // collection (because another thread beat us to it) or if we were 1012 // stalled due to the GC locker. In either can we should retry the 1013 // allocation attempt in case another thread successfully 1014 // performed a collection and reclaimed enough space. Give a 1015 // warning if we seem to be looping forever. 1016 1017 if ((QueuedAllocationWarningCount > 0) && 1018 (try_count % QueuedAllocationWarningCount == 0)) { 1019 warning("G1CollectedHeap::attempt_allocation_humongous() " 1020 "retries %d times", try_count); 1021 } 1022 } 1023 1024 ShouldNotReachHere(); 1025 return NULL; 1026 } 1027 1028 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1029 AllocationContext_t context, 1030 bool expect_null_mutator_alloc_region) { 1031 assert_at_safepoint(true /* should_be_vm_thread */); 1032 assert(_allocator->mutator_alloc_region(context)->get() == NULL || 1033 !expect_null_mutator_alloc_region, 1034 "the current alloc region was unexpectedly found to be non-NULL"); 1035 1036 if (!is_humongous(word_size)) { 1037 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, 1038 false /* bot_updates */); 1039 } else { 1040 HeapWord* result = humongous_obj_allocate(word_size, context); 1041 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1042 collector_state()->set_initiate_conc_mark_if_possible(true); 1043 } 1044 return result; 1045 } 1046 1047 ShouldNotReachHere(); 1048 } 1049 1050 class PostMCRemSetClearClosure: public HeapRegionClosure { 1051 G1CollectedHeap* _g1h; 1052 ModRefBarrierSet* _mr_bs; 1053 public: 1054 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1055 _g1h(g1h), _mr_bs(mr_bs) {} 1056 1057 bool doHeapRegion(HeapRegion* r) { 1058 HeapRegionRemSet* hrrs = r->rem_set(); 1059 1060 if (r->is_continues_humongous()) { 1061 // We'll assert that the strong code root list and RSet is empty 1062 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1063 assert(hrrs->occupied() == 0, "RSet should be empty"); 1064 return false; 1065 } 1066 1067 _g1h->reset_gc_time_stamps(r); 1068 hrrs->clear(); 1069 // You might think here that we could clear just the cards 1070 // corresponding to the used region. But no: if we leave a dirty card 1071 // in a region we might allocate into, then it would prevent that card 1072 // from being enqueued, and cause it to be missed. 1073 // Re: the performance cost: we shouldn't be doing full GC anyway! 1074 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1075 1076 return false; 1077 } 1078 }; 1079 1080 void G1CollectedHeap::clear_rsets_post_compaction() { 1081 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1082 heap_region_iterate(&rs_clear); 1083 } 1084 1085 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1086 G1CollectedHeap* _g1h; 1087 UpdateRSOopClosure _cl; 1088 public: 1089 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) : 1090 _cl(g1->g1_rem_set(), worker_i), 1091 _g1h(g1) 1092 { } 1093 1094 bool doHeapRegion(HeapRegion* r) { 1095 if (!r->is_continues_humongous()) { 1096 _cl.set_from(r); 1097 r->oop_iterate(&_cl); 1098 } 1099 return false; 1100 } 1101 }; 1102 1103 class ParRebuildRSTask: public AbstractGangTask { 1104 G1CollectedHeap* _g1; 1105 HeapRegionClaimer _hrclaimer; 1106 1107 public: 1108 ParRebuildRSTask(G1CollectedHeap* g1) : 1109 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {} 1110 1111 void work(uint worker_id) { 1112 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1113 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer); 1114 } 1115 }; 1116 1117 class PostCompactionPrinterClosure: public HeapRegionClosure { 1118 private: 1119 G1HRPrinter* _hr_printer; 1120 public: 1121 bool doHeapRegion(HeapRegion* hr) { 1122 assert(!hr->is_young(), "not expecting to find young regions"); 1123 if (hr->is_free()) { 1124 // We only generate output for non-empty regions. 1125 } else if (hr->is_starts_humongous()) { 1126 if (hr->region_num() == 1) { 1127 // single humongous region 1128 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1129 } else { 1130 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1131 } 1132 } else if (hr->is_continues_humongous()) { 1133 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1134 } else if (hr->is_old()) { 1135 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1136 } else { 1137 ShouldNotReachHere(); 1138 } 1139 return false; 1140 } 1141 1142 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1143 : _hr_printer(hr_printer) { } 1144 }; 1145 1146 void G1CollectedHeap::print_hrm_post_compaction() { 1147 PostCompactionPrinterClosure cl(hr_printer()); 1148 heap_region_iterate(&cl); 1149 } 1150 1151 bool G1CollectedHeap::do_collection(bool explicit_gc, 1152 bool clear_all_soft_refs, 1153 size_t word_size) { 1154 assert_at_safepoint(true /* should_be_vm_thread */); 1155 1156 if (GC_locker::check_active_before_gc()) { 1157 return false; 1158 } 1159 1160 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1161 gc_timer->register_gc_start(); 1162 1163 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1164 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1165 1166 SvcGCMarker sgcm(SvcGCMarker::FULL); 1167 ResourceMark rm; 1168 1169 G1Log::update_level(); 1170 print_heap_before_gc(); 1171 trace_heap_before_gc(gc_tracer); 1172 1173 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1174 1175 verify_region_sets_optional(); 1176 1177 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1178 collector_policy()->should_clear_all_soft_refs(); 1179 1180 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1181 1182 { 1183 IsGCActiveMark x; 1184 1185 // Timing 1186 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); 1187 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1188 1189 { 1190 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id()); 1191 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1192 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1193 1194 g1_policy()->record_full_collection_start(); 1195 1196 // Note: When we have a more flexible GC logging framework that 1197 // allows us to add optional attributes to a GC log record we 1198 // could consider timing and reporting how long we wait in the 1199 // following two methods. 1200 wait_while_free_regions_coming(); 1201 // If we start the compaction before the CM threads finish 1202 // scanning the root regions we might trip them over as we'll 1203 // be moving objects / updating references. So let's wait until 1204 // they are done. By telling them to abort, they should complete 1205 // early. 1206 _cm->root_regions()->abort(); 1207 _cm->root_regions()->wait_until_scan_finished(); 1208 append_secondary_free_list_if_not_empty_with_lock(); 1209 1210 gc_prologue(true); 1211 increment_total_collections(true /* full gc */); 1212 increment_old_marking_cycles_started(); 1213 1214 assert(used() == recalculate_used(), "Should be equal"); 1215 1216 verify_before_gc(); 1217 1218 check_bitmaps("Full GC Start"); 1219 pre_full_gc_dump(gc_timer); 1220 1221 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1222 1223 // Disable discovery and empty the discovered lists 1224 // for the CM ref processor. 1225 ref_processor_cm()->disable_discovery(); 1226 ref_processor_cm()->abandon_partial_discovery(); 1227 ref_processor_cm()->verify_no_references_recorded(); 1228 1229 // Abandon current iterations of concurrent marking and concurrent 1230 // refinement, if any are in progress. We have to do this before 1231 // wait_until_scan_finished() below. 1232 concurrent_mark()->abort(); 1233 1234 // Make sure we'll choose a new allocation region afterwards. 1235 _allocator->release_mutator_alloc_region(); 1236 _allocator->abandon_gc_alloc_regions(); 1237 g1_rem_set()->cleanupHRRS(); 1238 1239 // We should call this after we retire any currently active alloc 1240 // regions so that all the ALLOC / RETIRE events are generated 1241 // before the start GC event. 1242 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1243 1244 // We may have added regions to the current incremental collection 1245 // set between the last GC or pause and now. We need to clear the 1246 // incremental collection set and then start rebuilding it afresh 1247 // after this full GC. 1248 abandon_collection_set(g1_policy()->inc_cset_head()); 1249 g1_policy()->clear_incremental_cset(); 1250 g1_policy()->stop_incremental_cset_building(); 1251 1252 tear_down_region_sets(false /* free_list_only */); 1253 collector_state()->set_gcs_are_young(true); 1254 1255 // See the comments in g1CollectedHeap.hpp and 1256 // G1CollectedHeap::ref_processing_init() about 1257 // how reference processing currently works in G1. 1258 1259 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1260 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1261 1262 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1263 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1264 1265 ref_processor_stw()->enable_discovery(); 1266 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1267 1268 // Do collection work 1269 { 1270 HandleMark hm; // Discard invalid handles created during gc 1271 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1272 } 1273 1274 assert(num_free_regions() == 0, "we should not have added any free regions"); 1275 rebuild_region_sets(false /* free_list_only */); 1276 1277 // Enqueue any discovered reference objects that have 1278 // not been removed from the discovered lists. 1279 ref_processor_stw()->enqueue_discovered_references(); 1280 1281 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1282 1283 MemoryService::track_memory_usage(); 1284 1285 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1286 ref_processor_stw()->verify_no_references_recorded(); 1287 1288 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1289 ClassLoaderDataGraph::purge(); 1290 MetaspaceAux::verify_metrics(); 1291 1292 // Note: since we've just done a full GC, concurrent 1293 // marking is no longer active. Therefore we need not 1294 // re-enable reference discovery for the CM ref processor. 1295 // That will be done at the start of the next marking cycle. 1296 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1297 ref_processor_cm()->verify_no_references_recorded(); 1298 1299 reset_gc_time_stamp(); 1300 // Since everything potentially moved, we will clear all remembered 1301 // sets, and clear all cards. Later we will rebuild remembered 1302 // sets. We will also reset the GC time stamps of the regions. 1303 clear_rsets_post_compaction(); 1304 check_gc_time_stamps(); 1305 1306 // Resize the heap if necessary. 1307 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1308 1309 if (_hr_printer.is_active()) { 1310 // We should do this after we potentially resize the heap so 1311 // that all the COMMIT / UNCOMMIT events are generated before 1312 // the end GC event. 1313 1314 print_hrm_post_compaction(); 1315 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1316 } 1317 1318 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1319 if (hot_card_cache->use_cache()) { 1320 hot_card_cache->reset_card_counts(); 1321 hot_card_cache->reset_hot_cache(); 1322 } 1323 1324 // Rebuild remembered sets of all regions. 1325 uint n_workers = 1326 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1327 workers()->active_workers(), 1328 Threads::number_of_non_daemon_threads()); 1329 assert(UseDynamicNumberOfGCThreads || 1330 n_workers == workers()->total_workers(), 1331 "If not dynamic should be using all the workers"); 1332 workers()->set_active_workers(n_workers); 1333 // Set parallel threads in the heap (_n_par_threads) only 1334 // before a parallel phase and always reset it to 0 after 1335 // the phase so that the number of parallel threads does 1336 // no get carried forward to a serial phase where there 1337 // may be code that is "possibly_parallel". 1338 set_par_threads(n_workers); 1339 1340 ParRebuildRSTask rebuild_rs_task(this); 1341 assert(UseDynamicNumberOfGCThreads || 1342 workers()->active_workers() == workers()->total_workers(), 1343 "Unless dynamic should use total workers"); 1344 // Use the most recent number of active workers 1345 assert(workers()->active_workers() > 0, 1346 "Active workers not properly set"); 1347 set_par_threads(workers()->active_workers()); 1348 workers()->run_task(&rebuild_rs_task); 1349 set_par_threads(0); 1350 1351 // Rebuild the strong code root lists for each region 1352 rebuild_strong_code_roots(); 1353 1354 if (true) { // FIXME 1355 MetaspaceGC::compute_new_size(); 1356 } 1357 1358 #ifdef TRACESPINNING 1359 ParallelTaskTerminator::print_termination_counts(); 1360 #endif 1361 1362 // Discard all rset updates 1363 JavaThread::dirty_card_queue_set().abandon_logs(); 1364 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1365 1366 _young_list->reset_sampled_info(); 1367 // At this point there should be no regions in the 1368 // entire heap tagged as young. 1369 assert(check_young_list_empty(true /* check_heap */), 1370 "young list should be empty at this point"); 1371 1372 // Update the number of full collections that have been completed. 1373 increment_old_marking_cycles_completed(false /* concurrent */); 1374 1375 _hrm.verify_optional(); 1376 verify_region_sets_optional(); 1377 1378 verify_after_gc(); 1379 1380 // Clear the previous marking bitmap, if needed for bitmap verification. 1381 // Note we cannot do this when we clear the next marking bitmap in 1382 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1383 // objects marked during a full GC against the previous bitmap. 1384 // But we need to clear it before calling check_bitmaps below since 1385 // the full GC has compacted objects and updated TAMS but not updated 1386 // the prev bitmap. 1387 if (G1VerifyBitmaps) { 1388 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1389 } 1390 check_bitmaps("Full GC End"); 1391 1392 // Start a new incremental collection set for the next pause 1393 assert(g1_policy()->collection_set() == NULL, "must be"); 1394 g1_policy()->start_incremental_cset_building(); 1395 1396 clear_cset_fast_test(); 1397 1398 _allocator->init_mutator_alloc_region(); 1399 1400 g1_policy()->record_full_collection_end(); 1401 1402 if (G1Log::fine()) { 1403 g1_policy()->print_heap_transition(); 1404 } 1405 1406 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1407 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1408 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1409 // before any GC notifications are raised. 1410 g1mm()->update_sizes(); 1411 1412 gc_epilogue(true); 1413 } 1414 1415 if (G1Log::finer()) { 1416 g1_policy()->print_detailed_heap_transition(true /* full */); 1417 } 1418 1419 print_heap_after_gc(); 1420 trace_heap_after_gc(gc_tracer); 1421 1422 post_full_gc_dump(gc_timer); 1423 1424 gc_timer->register_gc_end(); 1425 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1426 } 1427 1428 return true; 1429 } 1430 1431 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1432 // do_collection() will return whether it succeeded in performing 1433 // the GC. Currently, there is no facility on the 1434 // do_full_collection() API to notify the caller than the collection 1435 // did not succeed (e.g., because it was locked out by the GC 1436 // locker). So, right now, we'll ignore the return value. 1437 bool dummy = do_collection(true, /* explicit_gc */ 1438 clear_all_soft_refs, 1439 0 /* word_size */); 1440 } 1441 1442 // This code is mostly copied from TenuredGeneration. 1443 void 1444 G1CollectedHeap:: 1445 resize_if_necessary_after_full_collection(size_t word_size) { 1446 // Include the current allocation, if any, and bytes that will be 1447 // pre-allocated to support collections, as "used". 1448 const size_t used_after_gc = used(); 1449 const size_t capacity_after_gc = capacity(); 1450 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1451 1452 // This is enforced in arguments.cpp. 1453 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1454 "otherwise the code below doesn't make sense"); 1455 1456 // We don't have floating point command-line arguments 1457 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1458 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1459 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1460 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1461 1462 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1463 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1464 1465 // We have to be careful here as these two calculations can overflow 1466 // 32-bit size_t's. 1467 double used_after_gc_d = (double) used_after_gc; 1468 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1469 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1470 1471 // Let's make sure that they are both under the max heap size, which 1472 // by default will make them fit into a size_t. 1473 double desired_capacity_upper_bound = (double) max_heap_size; 1474 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1475 desired_capacity_upper_bound); 1476 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1477 desired_capacity_upper_bound); 1478 1479 // We can now safely turn them into size_t's. 1480 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1481 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1482 1483 // This assert only makes sense here, before we adjust them 1484 // with respect to the min and max heap size. 1485 assert(minimum_desired_capacity <= maximum_desired_capacity, 1486 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1487 "maximum_desired_capacity = "SIZE_FORMAT, 1488 minimum_desired_capacity, maximum_desired_capacity)); 1489 1490 // Should not be greater than the heap max size. No need to adjust 1491 // it with respect to the heap min size as it's a lower bound (i.e., 1492 // we'll try to make the capacity larger than it, not smaller). 1493 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1494 // Should not be less than the heap min size. No need to adjust it 1495 // with respect to the heap max size as it's an upper bound (i.e., 1496 // we'll try to make the capacity smaller than it, not greater). 1497 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1498 1499 if (capacity_after_gc < minimum_desired_capacity) { 1500 // Don't expand unless it's significant 1501 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1502 ergo_verbose4(ErgoHeapSizing, 1503 "attempt heap expansion", 1504 ergo_format_reason("capacity lower than " 1505 "min desired capacity after Full GC") 1506 ergo_format_byte("capacity") 1507 ergo_format_byte("occupancy") 1508 ergo_format_byte_perc("min desired capacity"), 1509 capacity_after_gc, used_after_gc, 1510 minimum_desired_capacity, (double) MinHeapFreeRatio); 1511 expand(expand_bytes); 1512 1513 // No expansion, now see if we want to shrink 1514 } else if (capacity_after_gc > maximum_desired_capacity) { 1515 // Capacity too large, compute shrinking size 1516 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1517 ergo_verbose4(ErgoHeapSizing, 1518 "attempt heap shrinking", 1519 ergo_format_reason("capacity higher than " 1520 "max desired capacity after Full GC") 1521 ergo_format_byte("capacity") 1522 ergo_format_byte("occupancy") 1523 ergo_format_byte_perc("max desired capacity"), 1524 capacity_after_gc, used_after_gc, 1525 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1526 shrink(shrink_bytes); 1527 } 1528 } 1529 1530 1531 HeapWord* 1532 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1533 AllocationContext_t context, 1534 bool* succeeded) { 1535 assert_at_safepoint(true /* should_be_vm_thread */); 1536 1537 *succeeded = true; 1538 // Let's attempt the allocation first. 1539 HeapWord* result = 1540 attempt_allocation_at_safepoint(word_size, 1541 context, 1542 false /* expect_null_mutator_alloc_region */); 1543 if (result != NULL) { 1544 assert(*succeeded, "sanity"); 1545 return result; 1546 } 1547 1548 // In a G1 heap, we're supposed to keep allocation from failing by 1549 // incremental pauses. Therefore, at least for now, we'll favor 1550 // expansion over collection. (This might change in the future if we can 1551 // do something smarter than full collection to satisfy a failed alloc.) 1552 result = expand_and_allocate(word_size, context); 1553 if (result != NULL) { 1554 assert(*succeeded, "sanity"); 1555 return result; 1556 } 1557 1558 // Expansion didn't work, we'll try to do a Full GC. 1559 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1560 false, /* clear_all_soft_refs */ 1561 word_size); 1562 if (!gc_succeeded) { 1563 *succeeded = false; 1564 return NULL; 1565 } 1566 1567 // Retry the allocation 1568 result = attempt_allocation_at_safepoint(word_size, 1569 context, 1570 true /* expect_null_mutator_alloc_region */); 1571 if (result != NULL) { 1572 assert(*succeeded, "sanity"); 1573 return result; 1574 } 1575 1576 // Then, try a Full GC that will collect all soft references. 1577 gc_succeeded = do_collection(false, /* explicit_gc */ 1578 true, /* clear_all_soft_refs */ 1579 word_size); 1580 if (!gc_succeeded) { 1581 *succeeded = false; 1582 return NULL; 1583 } 1584 1585 // Retry the allocation once more 1586 result = attempt_allocation_at_safepoint(word_size, 1587 context, 1588 true /* expect_null_mutator_alloc_region */); 1589 if (result != NULL) { 1590 assert(*succeeded, "sanity"); 1591 return result; 1592 } 1593 1594 assert(!collector_policy()->should_clear_all_soft_refs(), 1595 "Flag should have been handled and cleared prior to this point"); 1596 1597 // What else? We might try synchronous finalization later. If the total 1598 // space available is large enough for the allocation, then a more 1599 // complete compaction phase than we've tried so far might be 1600 // appropriate. 1601 assert(*succeeded, "sanity"); 1602 return NULL; 1603 } 1604 1605 // Attempting to expand the heap sufficiently 1606 // to support an allocation of the given "word_size". If 1607 // successful, perform the allocation and return the address of the 1608 // allocated block, or else "NULL". 1609 1610 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1611 assert_at_safepoint(true /* should_be_vm_thread */); 1612 1613 verify_region_sets_optional(); 1614 1615 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1616 ergo_verbose1(ErgoHeapSizing, 1617 "attempt heap expansion", 1618 ergo_format_reason("allocation request failed") 1619 ergo_format_byte("allocation request"), 1620 word_size * HeapWordSize); 1621 if (expand(expand_bytes)) { 1622 _hrm.verify_optional(); 1623 verify_region_sets_optional(); 1624 return attempt_allocation_at_safepoint(word_size, 1625 context, 1626 false /* expect_null_mutator_alloc_region */); 1627 } 1628 return NULL; 1629 } 1630 1631 bool G1CollectedHeap::expand(size_t expand_bytes) { 1632 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1633 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1634 HeapRegion::GrainBytes); 1635 ergo_verbose2(ErgoHeapSizing, 1636 "expand the heap", 1637 ergo_format_byte("requested expansion amount") 1638 ergo_format_byte("attempted expansion amount"), 1639 expand_bytes, aligned_expand_bytes); 1640 1641 if (is_maximal_no_gc()) { 1642 ergo_verbose0(ErgoHeapSizing, 1643 "did not expand the heap", 1644 ergo_format_reason("heap already fully expanded")); 1645 return false; 1646 } 1647 1648 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1649 assert(regions_to_expand > 0, "Must expand by at least one region"); 1650 1651 uint expanded_by = _hrm.expand_by(regions_to_expand); 1652 1653 if (expanded_by > 0) { 1654 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1655 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1656 g1_policy()->record_new_heap_size(num_regions()); 1657 } else { 1658 ergo_verbose0(ErgoHeapSizing, 1659 "did not expand the heap", 1660 ergo_format_reason("heap expansion operation failed")); 1661 // The expansion of the virtual storage space was unsuccessful. 1662 // Let's see if it was because we ran out of swap. 1663 if (G1ExitOnExpansionFailure && 1664 _hrm.available() >= regions_to_expand) { 1665 // We had head room... 1666 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1667 } 1668 } 1669 return regions_to_expand > 0; 1670 } 1671 1672 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1673 size_t aligned_shrink_bytes = 1674 ReservedSpace::page_align_size_down(shrink_bytes); 1675 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1676 HeapRegion::GrainBytes); 1677 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1678 1679 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1680 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1681 1682 ergo_verbose3(ErgoHeapSizing, 1683 "shrink the heap", 1684 ergo_format_byte("requested shrinking amount") 1685 ergo_format_byte("aligned shrinking amount") 1686 ergo_format_byte("attempted shrinking amount"), 1687 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1688 if (num_regions_removed > 0) { 1689 g1_policy()->record_new_heap_size(num_regions()); 1690 } else { 1691 ergo_verbose0(ErgoHeapSizing, 1692 "did not shrink the heap", 1693 ergo_format_reason("heap shrinking operation failed")); 1694 } 1695 } 1696 1697 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1698 verify_region_sets_optional(); 1699 1700 // We should only reach here at the end of a Full GC which means we 1701 // should not not be holding to any GC alloc regions. The method 1702 // below will make sure of that and do any remaining clean up. 1703 _allocator->abandon_gc_alloc_regions(); 1704 1705 // Instead of tearing down / rebuilding the free lists here, we 1706 // could instead use the remove_all_pending() method on free_list to 1707 // remove only the ones that we need to remove. 1708 tear_down_region_sets(true /* free_list_only */); 1709 shrink_helper(shrink_bytes); 1710 rebuild_region_sets(true /* free_list_only */); 1711 1712 _hrm.verify_optional(); 1713 verify_region_sets_optional(); 1714 } 1715 1716 // Public methods. 1717 1718 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1719 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1720 #endif // _MSC_VER 1721 1722 1723 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1724 CollectedHeap(), 1725 _g1_policy(policy_), 1726 _dirty_card_queue_set(false), 1727 _into_cset_dirty_card_queue_set(false), 1728 _is_alive_closure_cm(this), 1729 _is_alive_closure_stw(this), 1730 _ref_processor_cm(NULL), 1731 _ref_processor_stw(NULL), 1732 _bot_shared(NULL), 1733 _evac_failure_scan_stack(NULL), 1734 _cg1r(NULL), 1735 _g1mm(NULL), 1736 _refine_cte_cl(NULL), 1737 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1738 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1739 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1740 _humongous_reclaim_candidates(), 1741 _has_humongous_reclaim_candidates(false), 1742 _free_regions_coming(false), 1743 _young_list(new YoungList(this)), 1744 _gc_time_stamp(0), 1745 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1746 _old_plab_stats(OldPLABSize, PLABWeight), 1747 _expand_heap_after_alloc_failure(true), 1748 _surviving_young_words(NULL), 1749 _old_marking_cycles_started(0), 1750 _old_marking_cycles_completed(0), 1751 _heap_summary_sent(false), 1752 _in_cset_fast_test(), 1753 _dirty_cards_region_list(NULL), 1754 _worker_cset_start_region(NULL), 1755 _worker_cset_start_region_time_stamp(NULL), 1756 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1757 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1758 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1759 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1760 1761 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads, 1762 /* are_GC_task_threads */true, 1763 /* are_ConcurrentGC_threads */false); 1764 _workers->initialize_workers(); 1765 1766 _allocator = G1Allocator::create_allocator(this); 1767 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1768 1769 int n_queues = MAX2((int)ParallelGCThreads, 1); 1770 _task_queues = new RefToScanQueueSet(n_queues); 1771 1772 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1773 assert(n_rem_sets > 0, "Invariant."); 1774 1775 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1776 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC); 1777 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1778 1779 for (int i = 0; i < n_queues; i++) { 1780 RefToScanQueue* q = new RefToScanQueue(); 1781 q->initialize(); 1782 _task_queues->register_queue(i, q); 1783 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1784 } 1785 clear_cset_start_regions(); 1786 1787 // Initialize the G1EvacuationFailureALot counters and flags. 1788 NOT_PRODUCT(reset_evacuation_should_fail();) 1789 1790 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1791 } 1792 1793 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1794 size_t size, 1795 size_t translation_factor) { 1796 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1797 // Allocate a new reserved space, preferring to use large pages. 1798 ReservedSpace rs(size, preferred_page_size); 1799 G1RegionToSpaceMapper* result = 1800 G1RegionToSpaceMapper::create_mapper(rs, 1801 size, 1802 rs.alignment(), 1803 HeapRegion::GrainBytes, 1804 translation_factor, 1805 mtGC); 1806 if (TracePageSizes) { 1807 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT, 1808 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size); 1809 } 1810 return result; 1811 } 1812 1813 jint G1CollectedHeap::initialize() { 1814 CollectedHeap::pre_initialize(); 1815 os::enable_vtime(); 1816 1817 G1Log::init(); 1818 1819 // Necessary to satisfy locking discipline assertions. 1820 1821 MutexLocker x(Heap_lock); 1822 1823 // We have to initialize the printer before committing the heap, as 1824 // it will be used then. 1825 _hr_printer.set_active(G1PrintHeapRegions); 1826 1827 // While there are no constraints in the GC code that HeapWordSize 1828 // be any particular value, there are multiple other areas in the 1829 // system which believe this to be true (e.g. oop->object_size in some 1830 // cases incorrectly returns the size in wordSize units rather than 1831 // HeapWordSize). 1832 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1833 1834 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1835 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1836 size_t heap_alignment = collector_policy()->heap_alignment(); 1837 1838 // Ensure that the sizes are properly aligned. 1839 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1840 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1841 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1842 1843 _refine_cte_cl = new RefineCardTableEntryClosure(); 1844 1845 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl); 1846 1847 // Reserve the maximum. 1848 1849 // When compressed oops are enabled, the preferred heap base 1850 // is calculated by subtracting the requested size from the 1851 // 32Gb boundary and using the result as the base address for 1852 // heap reservation. If the requested size is not aligned to 1853 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1854 // into the ReservedHeapSpace constructor) then the actual 1855 // base of the reserved heap may end up differing from the 1856 // address that was requested (i.e. the preferred heap base). 1857 // If this happens then we could end up using a non-optimal 1858 // compressed oops mode. 1859 1860 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1861 heap_alignment); 1862 1863 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1864 1865 // Create the barrier set for the entire reserved region. 1866 G1SATBCardTableLoggingModRefBS* bs 1867 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 1868 bs->initialize(); 1869 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 1870 set_barrier_set(bs); 1871 1872 // Also create a G1 rem set. 1873 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 1874 1875 // Carve out the G1 part of the heap. 1876 1877 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1878 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 1879 G1RegionToSpaceMapper* heap_storage = 1880 G1RegionToSpaceMapper::create_mapper(g1_rs, 1881 g1_rs.size(), 1882 page_size, 1883 HeapRegion::GrainBytes, 1884 1, 1885 mtJavaHeap); 1886 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(), 1887 max_byte_size, page_size, 1888 heap_rs.base(), 1889 heap_rs.size()); 1890 heap_storage->set_mapping_changed_listener(&_listener); 1891 1892 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1893 G1RegionToSpaceMapper* bot_storage = 1894 create_aux_memory_mapper("Block offset table", 1895 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize), 1896 G1BlockOffsetSharedArray::heap_map_factor()); 1897 1898 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 1899 G1RegionToSpaceMapper* cardtable_storage = 1900 create_aux_memory_mapper("Card table", 1901 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize), 1902 G1SATBCardTableLoggingModRefBS::heap_map_factor()); 1903 1904 G1RegionToSpaceMapper* card_counts_storage = 1905 create_aux_memory_mapper("Card counts table", 1906 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1907 G1CardCounts::heap_map_factor()); 1908 1909 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); 1910 G1RegionToSpaceMapper* prev_bitmap_storage = 1911 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor()); 1912 G1RegionToSpaceMapper* next_bitmap_storage = 1913 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor()); 1914 1915 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1916 g1_barrier_set()->initialize(cardtable_storage); 1917 // Do later initialization work for concurrent refinement. 1918 _cg1r->init(card_counts_storage); 1919 1920 // 6843694 - ensure that the maximum region index can fit 1921 // in the remembered set structures. 1922 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1923 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1924 1925 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1926 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1927 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1928 "too many cards per region"); 1929 1930 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1931 1932 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage); 1933 1934 { 1935 HeapWord* start = _hrm.reserved().start(); 1936 HeapWord* end = _hrm.reserved().end(); 1937 size_t granularity = HeapRegion::GrainBytes; 1938 1939 _in_cset_fast_test.initialize(start, end, granularity); 1940 _humongous_reclaim_candidates.initialize(start, end, granularity); 1941 } 1942 1943 // Create the ConcurrentMark data structure and thread. 1944 // (Must do this late, so that "max_regions" is defined.) 1945 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1946 if (_cm == NULL || !_cm->completed_initialization()) { 1947 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 1948 return JNI_ENOMEM; 1949 } 1950 _cmThread = _cm->cmThread(); 1951 1952 // Initialize the from_card cache structure of HeapRegionRemSet. 1953 HeapRegionRemSet::init_heap(max_regions()); 1954 1955 // Now expand into the initial heap size. 1956 if (!expand(init_byte_size)) { 1957 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1958 return JNI_ENOMEM; 1959 } 1960 1961 // Perform any initialization actions delegated to the policy. 1962 g1_policy()->init(); 1963 1964 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 1965 SATB_Q_FL_lock, 1966 G1SATBProcessCompletedThreshold, 1967 Shared_SATB_Q_lock); 1968 1969 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 1970 DirtyCardQ_CBL_mon, 1971 DirtyCardQ_FL_lock, 1972 concurrent_g1_refine()->yellow_zone(), 1973 concurrent_g1_refine()->red_zone(), 1974 Shared_DirtyCardQ_lock); 1975 1976 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 1977 DirtyCardQ_CBL_mon, 1978 DirtyCardQ_FL_lock, 1979 -1, // never trigger processing 1980 -1, // no limit on length 1981 Shared_DirtyCardQ_lock, 1982 &JavaThread::dirty_card_queue_set()); 1983 1984 // Initialize the card queue set used to hold cards containing 1985 // references into the collection set. 1986 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 1987 DirtyCardQ_CBL_mon, 1988 DirtyCardQ_FL_lock, 1989 -1, // never trigger processing 1990 -1, // no limit on length 1991 Shared_DirtyCardQ_lock, 1992 &JavaThread::dirty_card_queue_set()); 1993 1994 // Here we allocate the dummy HeapRegion that is required by the 1995 // G1AllocRegion class. 1996 HeapRegion* dummy_region = _hrm.get_dummy_region(); 1997 1998 // We'll re-use the same region whether the alloc region will 1999 // require BOT updates or not and, if it doesn't, then a non-young 2000 // region will complain that it cannot support allocations without 2001 // BOT updates. So we'll tag the dummy region as eden to avoid that. 2002 dummy_region->set_eden(); 2003 // Make sure it's full. 2004 dummy_region->set_top(dummy_region->end()); 2005 G1AllocRegion::setup(this, dummy_region); 2006 2007 _allocator->init_mutator_alloc_region(); 2008 2009 // Do create of the monitoring and management support so that 2010 // values in the heap have been properly initialized. 2011 _g1mm = new G1MonitoringSupport(this); 2012 2013 G1StringDedup::initialize(); 2014 2015 return JNI_OK; 2016 } 2017 2018 void G1CollectedHeap::stop() { 2019 // Stop all concurrent threads. We do this to make sure these threads 2020 // do not continue to execute and access resources (e.g. gclog_or_tty) 2021 // that are destroyed during shutdown. 2022 _cg1r->stop(); 2023 _cmThread->stop(); 2024 if (G1StringDedup::is_enabled()) { 2025 G1StringDedup::stop(); 2026 } 2027 } 2028 2029 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2030 return HeapRegion::max_region_size(); 2031 } 2032 2033 void G1CollectedHeap::post_initialize() { 2034 CollectedHeap::post_initialize(); 2035 ref_processing_init(); 2036 } 2037 2038 void G1CollectedHeap::ref_processing_init() { 2039 // Reference processing in G1 currently works as follows: 2040 // 2041 // * There are two reference processor instances. One is 2042 // used to record and process discovered references 2043 // during concurrent marking; the other is used to 2044 // record and process references during STW pauses 2045 // (both full and incremental). 2046 // * Both ref processors need to 'span' the entire heap as 2047 // the regions in the collection set may be dotted around. 2048 // 2049 // * For the concurrent marking ref processor: 2050 // * Reference discovery is enabled at initial marking. 2051 // * Reference discovery is disabled and the discovered 2052 // references processed etc during remarking. 2053 // * Reference discovery is MT (see below). 2054 // * Reference discovery requires a barrier (see below). 2055 // * Reference processing may or may not be MT 2056 // (depending on the value of ParallelRefProcEnabled 2057 // and ParallelGCThreads). 2058 // * A full GC disables reference discovery by the CM 2059 // ref processor and abandons any entries on it's 2060 // discovered lists. 2061 // 2062 // * For the STW processor: 2063 // * Non MT discovery is enabled at the start of a full GC. 2064 // * Processing and enqueueing during a full GC is non-MT. 2065 // * During a full GC, references are processed after marking. 2066 // 2067 // * Discovery (may or may not be MT) is enabled at the start 2068 // of an incremental evacuation pause. 2069 // * References are processed near the end of a STW evacuation pause. 2070 // * For both types of GC: 2071 // * Discovery is atomic - i.e. not concurrent. 2072 // * Reference discovery will not need a barrier. 2073 2074 MemRegion mr = reserved_region(); 2075 2076 // Concurrent Mark ref processor 2077 _ref_processor_cm = 2078 new ReferenceProcessor(mr, // span 2079 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2080 // mt processing 2081 (int) ParallelGCThreads, 2082 // degree of mt processing 2083 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2084 // mt discovery 2085 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2086 // degree of mt discovery 2087 false, 2088 // Reference discovery is not atomic 2089 &_is_alive_closure_cm); 2090 // is alive closure 2091 // (for efficiency/performance) 2092 2093 // STW ref processor 2094 _ref_processor_stw = 2095 new ReferenceProcessor(mr, // span 2096 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2097 // mt processing 2098 MAX2((int)ParallelGCThreads, 1), 2099 // degree of mt processing 2100 (ParallelGCThreads > 1), 2101 // mt discovery 2102 MAX2((int)ParallelGCThreads, 1), 2103 // degree of mt discovery 2104 true, 2105 // Reference discovery is atomic 2106 &_is_alive_closure_stw); 2107 // is alive closure 2108 // (for efficiency/performance) 2109 } 2110 2111 size_t G1CollectedHeap::capacity() const { 2112 return _hrm.length() * HeapRegion::GrainBytes; 2113 } 2114 2115 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2116 assert(!hr->is_continues_humongous(), "pre-condition"); 2117 hr->reset_gc_time_stamp(); 2118 if (hr->is_starts_humongous()) { 2119 uint first_index = hr->hrm_index() + 1; 2120 uint last_index = hr->last_hc_index(); 2121 for (uint i = first_index; i < last_index; i += 1) { 2122 HeapRegion* chr = region_at(i); 2123 assert(chr->is_continues_humongous(), "sanity"); 2124 chr->reset_gc_time_stamp(); 2125 } 2126 } 2127 } 2128 2129 #ifndef PRODUCT 2130 2131 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2132 private: 2133 unsigned _gc_time_stamp; 2134 bool _failures; 2135 2136 public: 2137 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2138 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2139 2140 virtual bool doHeapRegion(HeapRegion* hr) { 2141 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2142 if (_gc_time_stamp != region_gc_time_stamp) { 2143 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2144 "expected %d", HR_FORMAT_PARAMS(hr), 2145 region_gc_time_stamp, _gc_time_stamp); 2146 _failures = true; 2147 } 2148 return false; 2149 } 2150 2151 bool failures() { return _failures; } 2152 }; 2153 2154 void G1CollectedHeap::check_gc_time_stamps() { 2155 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2156 heap_region_iterate(&cl); 2157 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2158 } 2159 #endif // PRODUCT 2160 2161 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2162 DirtyCardQueue* into_cset_dcq, 2163 bool concurrent, 2164 uint worker_i) { 2165 // Clean cards in the hot card cache 2166 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2167 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2168 2169 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2170 size_t n_completed_buffers = 0; 2171 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2172 n_completed_buffers++; 2173 } 2174 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 2175 dcqs.clear_n_completed_buffers(); 2176 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2177 } 2178 2179 2180 // Computes the sum of the storage used by the various regions. 2181 size_t G1CollectedHeap::used() const { 2182 return _allocator->used(); 2183 } 2184 2185 size_t G1CollectedHeap::used_unlocked() const { 2186 return _allocator->used_unlocked(); 2187 } 2188 2189 class SumUsedClosure: public HeapRegionClosure { 2190 size_t _used; 2191 public: 2192 SumUsedClosure() : _used(0) {} 2193 bool doHeapRegion(HeapRegion* r) { 2194 if (!r->is_continues_humongous()) { 2195 _used += r->used(); 2196 } 2197 return false; 2198 } 2199 size_t result() { return _used; } 2200 }; 2201 2202 size_t G1CollectedHeap::recalculate_used() const { 2203 double recalculate_used_start = os::elapsedTime(); 2204 2205 SumUsedClosure blk; 2206 heap_region_iterate(&blk); 2207 2208 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2209 return blk.result(); 2210 } 2211 2212 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2213 switch (cause) { 2214 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2215 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2216 case GCCause::_g1_humongous_allocation: return true; 2217 case GCCause::_update_allocation_context_stats_inc: return true; 2218 case GCCause::_wb_conc_mark: return true; 2219 default: return false; 2220 } 2221 } 2222 2223 #ifndef PRODUCT 2224 void G1CollectedHeap::allocate_dummy_regions() { 2225 // Let's fill up most of the region 2226 size_t word_size = HeapRegion::GrainWords - 1024; 2227 // And as a result the region we'll allocate will be humongous. 2228 guarantee(is_humongous(word_size), "sanity"); 2229 2230 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2231 // Let's use the existing mechanism for the allocation 2232 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2233 AllocationContext::system()); 2234 if (dummy_obj != NULL) { 2235 MemRegion mr(dummy_obj, word_size); 2236 CollectedHeap::fill_with_object(mr); 2237 } else { 2238 // If we can't allocate once, we probably cannot allocate 2239 // again. Let's get out of the loop. 2240 break; 2241 } 2242 } 2243 } 2244 #endif // !PRODUCT 2245 2246 void G1CollectedHeap::increment_old_marking_cycles_started() { 2247 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2248 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2249 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2250 _old_marking_cycles_started, _old_marking_cycles_completed)); 2251 2252 _old_marking_cycles_started++; 2253 } 2254 2255 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2256 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2257 2258 // We assume that if concurrent == true, then the caller is a 2259 // concurrent thread that was joined the Suspendible Thread 2260 // Set. If there's ever a cheap way to check this, we should add an 2261 // assert here. 2262 2263 // Given that this method is called at the end of a Full GC or of a 2264 // concurrent cycle, and those can be nested (i.e., a Full GC can 2265 // interrupt a concurrent cycle), the number of full collections 2266 // completed should be either one (in the case where there was no 2267 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2268 // behind the number of full collections started. 2269 2270 // This is the case for the inner caller, i.e. a Full GC. 2271 assert(concurrent || 2272 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2273 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2274 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2275 "is inconsistent with _old_marking_cycles_completed = %u", 2276 _old_marking_cycles_started, _old_marking_cycles_completed)); 2277 2278 // This is the case for the outer caller, i.e. the concurrent cycle. 2279 assert(!concurrent || 2280 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2281 err_msg("for outer caller (concurrent cycle): " 2282 "_old_marking_cycles_started = %u " 2283 "is inconsistent with _old_marking_cycles_completed = %u", 2284 _old_marking_cycles_started, _old_marking_cycles_completed)); 2285 2286 _old_marking_cycles_completed += 1; 2287 2288 // We need to clear the "in_progress" flag in the CM thread before 2289 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2290 // is set) so that if a waiter requests another System.gc() it doesn't 2291 // incorrectly see that a marking cycle is still in progress. 2292 if (concurrent) { 2293 _cmThread->clear_in_progress(); 2294 } 2295 2296 // This notify_all() will ensure that a thread that called 2297 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2298 // and it's waiting for a full GC to finish will be woken up. It is 2299 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2300 FullGCCount_lock->notify_all(); 2301 } 2302 2303 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2304 collector_state()->set_concurrent_cycle_started(true); 2305 _gc_timer_cm->register_gc_start(start_time); 2306 2307 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2308 trace_heap_before_gc(_gc_tracer_cm); 2309 } 2310 2311 void G1CollectedHeap::register_concurrent_cycle_end() { 2312 if (collector_state()->concurrent_cycle_started()) { 2313 if (_cm->has_aborted()) { 2314 _gc_tracer_cm->report_concurrent_mode_failure(); 2315 } 2316 2317 _gc_timer_cm->register_gc_end(); 2318 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2319 2320 // Clear state variables to prepare for the next concurrent cycle. 2321 collector_state()->set_concurrent_cycle_started(false); 2322 _heap_summary_sent = false; 2323 } 2324 } 2325 2326 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2327 if (collector_state()->concurrent_cycle_started()) { 2328 // This function can be called when: 2329 // the cleanup pause is run 2330 // the concurrent cycle is aborted before the cleanup pause. 2331 // the concurrent cycle is aborted after the cleanup pause, 2332 // but before the concurrent cycle end has been registered. 2333 // Make sure that we only send the heap information once. 2334 if (!_heap_summary_sent) { 2335 trace_heap_after_gc(_gc_tracer_cm); 2336 _heap_summary_sent = true; 2337 } 2338 } 2339 } 2340 2341 G1YCType G1CollectedHeap::yc_type() { 2342 bool is_young = collector_state()->gcs_are_young(); 2343 bool is_initial_mark = collector_state()->during_initial_mark_pause(); 2344 bool is_during_mark = collector_state()->mark_in_progress(); 2345 2346 if (is_initial_mark) { 2347 return InitialMark; 2348 } else if (is_during_mark) { 2349 return DuringMark; 2350 } else if (is_young) { 2351 return Normal; 2352 } else { 2353 return Mixed; 2354 } 2355 } 2356 2357 void G1CollectedHeap::collect(GCCause::Cause cause) { 2358 assert_heap_not_locked(); 2359 2360 uint gc_count_before; 2361 uint old_marking_count_before; 2362 uint full_gc_count_before; 2363 bool retry_gc; 2364 2365 do { 2366 retry_gc = false; 2367 2368 { 2369 MutexLocker ml(Heap_lock); 2370 2371 // Read the GC count while holding the Heap_lock 2372 gc_count_before = total_collections(); 2373 full_gc_count_before = total_full_collections(); 2374 old_marking_count_before = _old_marking_cycles_started; 2375 } 2376 2377 if (should_do_concurrent_full_gc(cause)) { 2378 // Schedule an initial-mark evacuation pause that will start a 2379 // concurrent cycle. We're setting word_size to 0 which means that 2380 // we are not requesting a post-GC allocation. 2381 VM_G1IncCollectionPause op(gc_count_before, 2382 0, /* word_size */ 2383 true, /* should_initiate_conc_mark */ 2384 g1_policy()->max_pause_time_ms(), 2385 cause); 2386 op.set_allocation_context(AllocationContext::current()); 2387 2388 VMThread::execute(&op); 2389 if (!op.pause_succeeded()) { 2390 if (old_marking_count_before == _old_marking_cycles_started) { 2391 retry_gc = op.should_retry_gc(); 2392 } else { 2393 // A Full GC happened while we were trying to schedule the 2394 // initial-mark GC. No point in starting a new cycle given 2395 // that the whole heap was collected anyway. 2396 } 2397 2398 if (retry_gc) { 2399 if (GC_locker::is_active_and_needs_gc()) { 2400 GC_locker::stall_until_clear(); 2401 } 2402 } 2403 } 2404 } else { 2405 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2406 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2407 2408 // Schedule a standard evacuation pause. We're setting word_size 2409 // to 0 which means that we are not requesting a post-GC allocation. 2410 VM_G1IncCollectionPause op(gc_count_before, 2411 0, /* word_size */ 2412 false, /* should_initiate_conc_mark */ 2413 g1_policy()->max_pause_time_ms(), 2414 cause); 2415 VMThread::execute(&op); 2416 } else { 2417 // Schedule a Full GC. 2418 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2419 VMThread::execute(&op); 2420 } 2421 } 2422 } while (retry_gc); 2423 } 2424 2425 bool G1CollectedHeap::is_in(const void* p) const { 2426 if (_hrm.reserved().contains(p)) { 2427 // Given that we know that p is in the reserved space, 2428 // heap_region_containing_raw() should successfully 2429 // return the containing region. 2430 HeapRegion* hr = heap_region_containing_raw(p); 2431 return hr->is_in(p); 2432 } else { 2433 return false; 2434 } 2435 } 2436 2437 #ifdef ASSERT 2438 bool G1CollectedHeap::is_in_exact(const void* p) const { 2439 bool contains = reserved_region().contains(p); 2440 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2441 if (contains && available) { 2442 return true; 2443 } else { 2444 return false; 2445 } 2446 } 2447 #endif 2448 2449 // Iteration functions. 2450 2451 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2452 2453 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2454 ExtendedOopClosure* _cl; 2455 public: 2456 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2457 bool doHeapRegion(HeapRegion* r) { 2458 if (!r->is_continues_humongous()) { 2459 r->oop_iterate(_cl); 2460 } 2461 return false; 2462 } 2463 }; 2464 2465 // Iterates an ObjectClosure over all objects within a HeapRegion. 2466 2467 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2468 ObjectClosure* _cl; 2469 public: 2470 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2471 bool doHeapRegion(HeapRegion* r) { 2472 if (!r->is_continues_humongous()) { 2473 r->object_iterate(_cl); 2474 } 2475 return false; 2476 } 2477 }; 2478 2479 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2480 IterateObjectClosureRegionClosure blk(cl); 2481 heap_region_iterate(&blk); 2482 } 2483 2484 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2485 _hrm.iterate(cl); 2486 } 2487 2488 void 2489 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, 2490 uint worker_id, 2491 HeapRegionClaimer *hrclaimer, 2492 bool concurrent) const { 2493 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); 2494 } 2495 2496 // Clear the cached CSet starting regions and (more importantly) 2497 // the time stamps. Called when we reset the GC time stamp. 2498 void G1CollectedHeap::clear_cset_start_regions() { 2499 assert(_worker_cset_start_region != NULL, "sanity"); 2500 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2501 2502 int n_queues = MAX2((int)ParallelGCThreads, 1); 2503 for (int i = 0; i < n_queues; i++) { 2504 _worker_cset_start_region[i] = NULL; 2505 _worker_cset_start_region_time_stamp[i] = 0; 2506 } 2507 } 2508 2509 // Given the id of a worker, obtain or calculate a suitable 2510 // starting region for iterating over the current collection set. 2511 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2512 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2513 2514 HeapRegion* result = NULL; 2515 unsigned gc_time_stamp = get_gc_time_stamp(); 2516 2517 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2518 // Cached starting region for current worker was set 2519 // during the current pause - so it's valid. 2520 // Note: the cached starting heap region may be NULL 2521 // (when the collection set is empty). 2522 result = _worker_cset_start_region[worker_i]; 2523 assert(result == NULL || result->in_collection_set(), "sanity"); 2524 return result; 2525 } 2526 2527 // The cached entry was not valid so let's calculate 2528 // a suitable starting heap region for this worker. 2529 2530 // We want the parallel threads to start their collection 2531 // set iteration at different collection set regions to 2532 // avoid contention. 2533 // If we have: 2534 // n collection set regions 2535 // p threads 2536 // Then thread t will start at region floor ((t * n) / p) 2537 2538 result = g1_policy()->collection_set(); 2539 uint cs_size = g1_policy()->cset_region_length(); 2540 uint active_workers = workers()->active_workers(); 2541 assert(UseDynamicNumberOfGCThreads || 2542 active_workers == workers()->total_workers(), 2543 "Unless dynamic should use total workers"); 2544 2545 uint end_ind = (cs_size * worker_i) / active_workers; 2546 uint start_ind = 0; 2547 2548 if (worker_i > 0 && 2549 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2550 // Previous workers starting region is valid 2551 // so let's iterate from there 2552 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2553 result = _worker_cset_start_region[worker_i - 1]; 2554 } 2555 2556 for (uint i = start_ind; i < end_ind; i++) { 2557 result = result->next_in_collection_set(); 2558 } 2559 2560 // Note: the calculated starting heap region may be NULL 2561 // (when the collection set is empty). 2562 assert(result == NULL || result->in_collection_set(), "sanity"); 2563 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2564 "should be updated only once per pause"); 2565 _worker_cset_start_region[worker_i] = result; 2566 OrderAccess::storestore(); 2567 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2568 return result; 2569 } 2570 2571 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2572 HeapRegion* r = g1_policy()->collection_set(); 2573 while (r != NULL) { 2574 HeapRegion* next = r->next_in_collection_set(); 2575 if (cl->doHeapRegion(r)) { 2576 cl->incomplete(); 2577 return; 2578 } 2579 r = next; 2580 } 2581 } 2582 2583 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2584 HeapRegionClosure *cl) { 2585 if (r == NULL) { 2586 // The CSet is empty so there's nothing to do. 2587 return; 2588 } 2589 2590 assert(r->in_collection_set(), 2591 "Start region must be a member of the collection set."); 2592 HeapRegion* cur = r; 2593 while (cur != NULL) { 2594 HeapRegion* next = cur->next_in_collection_set(); 2595 if (cl->doHeapRegion(cur) && false) { 2596 cl->incomplete(); 2597 return; 2598 } 2599 cur = next; 2600 } 2601 cur = g1_policy()->collection_set(); 2602 while (cur != r) { 2603 HeapRegion* next = cur->next_in_collection_set(); 2604 if (cl->doHeapRegion(cur) && false) { 2605 cl->incomplete(); 2606 return; 2607 } 2608 cur = next; 2609 } 2610 } 2611 2612 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2613 HeapRegion* result = _hrm.next_region_in_heap(from); 2614 while (result != NULL && result->is_humongous()) { 2615 result = _hrm.next_region_in_heap(result); 2616 } 2617 return result; 2618 } 2619 2620 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2621 HeapRegion* hr = heap_region_containing(addr); 2622 return hr->block_start(addr); 2623 } 2624 2625 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2626 HeapRegion* hr = heap_region_containing(addr); 2627 return hr->block_size(addr); 2628 } 2629 2630 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2631 HeapRegion* hr = heap_region_containing(addr); 2632 return hr->block_is_obj(addr); 2633 } 2634 2635 bool G1CollectedHeap::supports_tlab_allocation() const { 2636 return true; 2637 } 2638 2639 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2640 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2641 } 2642 2643 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2644 return young_list()->eden_used_bytes(); 2645 } 2646 2647 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2648 // must be smaller than the humongous object limit. 2649 size_t G1CollectedHeap::max_tlab_size() const { 2650 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 2651 } 2652 2653 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2654 // Return the remaining space in the cur alloc region, but not less than 2655 // the min TLAB size. 2656 2657 // Also, this value can be at most the humongous object threshold, 2658 // since we can't allow tlabs to grow big enough to accommodate 2659 // humongous objects. 2660 2661 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get(); 2662 size_t max_tlab = max_tlab_size() * wordSize; 2663 if (hr == NULL) { 2664 return max_tlab; 2665 } else { 2666 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 2667 } 2668 } 2669 2670 size_t G1CollectedHeap::max_capacity() const { 2671 return _hrm.reserved().byte_size(); 2672 } 2673 2674 jlong G1CollectedHeap::millis_since_last_gc() { 2675 // assert(false, "NYI"); 2676 return 0; 2677 } 2678 2679 void G1CollectedHeap::prepare_for_verify() { 2680 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2681 ensure_parsability(false); 2682 } 2683 g1_rem_set()->prepare_for_verify(); 2684 } 2685 2686 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 2687 VerifyOption vo) { 2688 switch (vo) { 2689 case VerifyOption_G1UsePrevMarking: 2690 return hr->obj_allocated_since_prev_marking(obj); 2691 case VerifyOption_G1UseNextMarking: 2692 return hr->obj_allocated_since_next_marking(obj); 2693 case VerifyOption_G1UseMarkWord: 2694 return false; 2695 default: 2696 ShouldNotReachHere(); 2697 } 2698 return false; // keep some compilers happy 2699 } 2700 2701 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 2702 switch (vo) { 2703 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 2704 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 2705 case VerifyOption_G1UseMarkWord: return NULL; 2706 default: ShouldNotReachHere(); 2707 } 2708 return NULL; // keep some compilers happy 2709 } 2710 2711 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 2712 switch (vo) { 2713 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 2714 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 2715 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 2716 default: ShouldNotReachHere(); 2717 } 2718 return false; // keep some compilers happy 2719 } 2720 2721 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 2722 switch (vo) { 2723 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 2724 case VerifyOption_G1UseNextMarking: return "NTAMS"; 2725 case VerifyOption_G1UseMarkWord: return "NONE"; 2726 default: ShouldNotReachHere(); 2727 } 2728 return NULL; // keep some compilers happy 2729 } 2730 2731 class VerifyRootsClosure: public OopClosure { 2732 private: 2733 G1CollectedHeap* _g1h; 2734 VerifyOption _vo; 2735 bool _failures; 2736 public: 2737 // _vo == UsePrevMarking -> use "prev" marking information, 2738 // _vo == UseNextMarking -> use "next" marking information, 2739 // _vo == UseMarkWord -> use mark word from object header. 2740 VerifyRootsClosure(VerifyOption vo) : 2741 _g1h(G1CollectedHeap::heap()), 2742 _vo(vo), 2743 _failures(false) { } 2744 2745 bool failures() { return _failures; } 2746 2747 template <class T> void do_oop_nv(T* p) { 2748 T heap_oop = oopDesc::load_heap_oop(p); 2749 if (!oopDesc::is_null(heap_oop)) { 2750 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2751 if (_g1h->is_obj_dead_cond(obj, _vo)) { 2752 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 2753 "points to dead obj "PTR_FORMAT, p2i(p), p2i(obj)); 2754 if (_vo == VerifyOption_G1UseMarkWord) { 2755 gclog_or_tty->print_cr(" Mark word: "INTPTR_FORMAT, (intptr_t)obj->mark()); 2756 } 2757 obj->print_on(gclog_or_tty); 2758 _failures = true; 2759 } 2760 } 2761 } 2762 2763 void do_oop(oop* p) { do_oop_nv(p); } 2764 void do_oop(narrowOop* p) { do_oop_nv(p); } 2765 }; 2766 2767 class G1VerifyCodeRootOopClosure: public OopClosure { 2768 G1CollectedHeap* _g1h; 2769 OopClosure* _root_cl; 2770 nmethod* _nm; 2771 VerifyOption _vo; 2772 bool _failures; 2773 2774 template <class T> void do_oop_work(T* p) { 2775 // First verify that this root is live 2776 _root_cl->do_oop(p); 2777 2778 if (!G1VerifyHeapRegionCodeRoots) { 2779 // We're not verifying the code roots attached to heap region. 2780 return; 2781 } 2782 2783 // Don't check the code roots during marking verification in a full GC 2784 if (_vo == VerifyOption_G1UseMarkWord) { 2785 return; 2786 } 2787 2788 // Now verify that the current nmethod (which contains p) is 2789 // in the code root list of the heap region containing the 2790 // object referenced by p. 2791 2792 T heap_oop = oopDesc::load_heap_oop(p); 2793 if (!oopDesc::is_null(heap_oop)) { 2794 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2795 2796 // Now fetch the region containing the object 2797 HeapRegion* hr = _g1h->heap_region_containing(obj); 2798 HeapRegionRemSet* hrrs = hr->rem_set(); 2799 // Verify that the strong code root list for this region 2800 // contains the nmethod 2801 if (!hrrs->strong_code_roots_list_contains(_nm)) { 2802 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " 2803 "from nmethod "PTR_FORMAT" not in strong " 2804 "code roots for region ["PTR_FORMAT","PTR_FORMAT")", 2805 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end())); 2806 _failures = true; 2807 } 2808 } 2809 } 2810 2811 public: 2812 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 2813 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 2814 2815 void do_oop(oop* p) { do_oop_work(p); } 2816 void do_oop(narrowOop* p) { do_oop_work(p); } 2817 2818 void set_nmethod(nmethod* nm) { _nm = nm; } 2819 bool failures() { return _failures; } 2820 }; 2821 2822 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 2823 G1VerifyCodeRootOopClosure* _oop_cl; 2824 2825 public: 2826 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 2827 _oop_cl(oop_cl) {} 2828 2829 void do_code_blob(CodeBlob* cb) { 2830 nmethod* nm = cb->as_nmethod_or_null(); 2831 if (nm != NULL) { 2832 _oop_cl->set_nmethod(nm); 2833 nm->oops_do(_oop_cl); 2834 } 2835 } 2836 }; 2837 2838 class YoungRefCounterClosure : public OopClosure { 2839 G1CollectedHeap* _g1h; 2840 int _count; 2841 public: 2842 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 2843 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 2844 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 2845 2846 int count() { return _count; } 2847 void reset_count() { _count = 0; }; 2848 }; 2849 2850 class VerifyKlassClosure: public KlassClosure { 2851 YoungRefCounterClosure _young_ref_counter_closure; 2852 OopClosure *_oop_closure; 2853 public: 2854 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 2855 void do_klass(Klass* k) { 2856 k->oops_do(_oop_closure); 2857 2858 _young_ref_counter_closure.reset_count(); 2859 k->oops_do(&_young_ref_counter_closure); 2860 if (_young_ref_counter_closure.count() > 0) { 2861 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k))); 2862 } 2863 } 2864 }; 2865 2866 class VerifyLivenessOopClosure: public OopClosure { 2867 G1CollectedHeap* _g1h; 2868 VerifyOption _vo; 2869 public: 2870 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 2871 _g1h(g1h), _vo(vo) 2872 { } 2873 void do_oop(narrowOop *p) { do_oop_work(p); } 2874 void do_oop( oop *p) { do_oop_work(p); } 2875 2876 template <class T> void do_oop_work(T *p) { 2877 oop obj = oopDesc::load_decode_heap_oop(p); 2878 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 2879 "Dead object referenced by a not dead object"); 2880 } 2881 }; 2882 2883 class VerifyObjsInRegionClosure: public ObjectClosure { 2884 private: 2885 G1CollectedHeap* _g1h; 2886 size_t _live_bytes; 2887 HeapRegion *_hr; 2888 VerifyOption _vo; 2889 public: 2890 // _vo == UsePrevMarking -> use "prev" marking information, 2891 // _vo == UseNextMarking -> use "next" marking information, 2892 // _vo == UseMarkWord -> use mark word from object header. 2893 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 2894 : _live_bytes(0), _hr(hr), _vo(vo) { 2895 _g1h = G1CollectedHeap::heap(); 2896 } 2897 void do_object(oop o) { 2898 VerifyLivenessOopClosure isLive(_g1h, _vo); 2899 assert(o != NULL, "Huh?"); 2900 if (!_g1h->is_obj_dead_cond(o, _vo)) { 2901 // If the object is alive according to the mark word, 2902 // then verify that the marking information agrees. 2903 // Note we can't verify the contra-positive of the 2904 // above: if the object is dead (according to the mark 2905 // word), it may not be marked, or may have been marked 2906 // but has since became dead, or may have been allocated 2907 // since the last marking. 2908 if (_vo == VerifyOption_G1UseMarkWord) { 2909 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 2910 } 2911 2912 o->oop_iterate_no_header(&isLive); 2913 if (!_hr->obj_allocated_since_prev_marking(o)) { 2914 size_t obj_size = o->size(); // Make sure we don't overflow 2915 _live_bytes += (obj_size * HeapWordSize); 2916 } 2917 } 2918 } 2919 size_t live_bytes() { return _live_bytes; } 2920 }; 2921 2922 class VerifyRegionClosure: public HeapRegionClosure { 2923 private: 2924 bool _par; 2925 VerifyOption _vo; 2926 bool _failures; 2927 public: 2928 // _vo == UsePrevMarking -> use "prev" marking information, 2929 // _vo == UseNextMarking -> use "next" marking information, 2930 // _vo == UseMarkWord -> use mark word from object header. 2931 VerifyRegionClosure(bool par, VerifyOption vo) 2932 : _par(par), 2933 _vo(vo), 2934 _failures(false) {} 2935 2936 bool failures() { 2937 return _failures; 2938 } 2939 2940 bool doHeapRegion(HeapRegion* r) { 2941 if (!r->is_continues_humongous()) { 2942 bool failures = false; 2943 r->verify(_vo, &failures); 2944 if (failures) { 2945 _failures = true; 2946 } else { 2947 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 2948 r->object_iterate(¬_dead_yet_cl); 2949 if (_vo != VerifyOption_G1UseNextMarking) { 2950 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 2951 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 2952 "max_live_bytes "SIZE_FORMAT" " 2953 "< calculated "SIZE_FORMAT, 2954 p2i(r->bottom()), p2i(r->end()), 2955 r->max_live_bytes(), 2956 not_dead_yet_cl.live_bytes()); 2957 _failures = true; 2958 } 2959 } else { 2960 // When vo == UseNextMarking we cannot currently do a sanity 2961 // check on the live bytes as the calculation has not been 2962 // finalized yet. 2963 } 2964 } 2965 } 2966 return false; // stop the region iteration if we hit a failure 2967 } 2968 }; 2969 2970 // This is the task used for parallel verification of the heap regions 2971 2972 class G1ParVerifyTask: public AbstractGangTask { 2973 private: 2974 G1CollectedHeap* _g1h; 2975 VerifyOption _vo; 2976 bool _failures; 2977 HeapRegionClaimer _hrclaimer; 2978 2979 public: 2980 // _vo == UsePrevMarking -> use "prev" marking information, 2981 // _vo == UseNextMarking -> use "next" marking information, 2982 // _vo == UseMarkWord -> use mark word from object header. 2983 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 2984 AbstractGangTask("Parallel verify task"), 2985 _g1h(g1h), 2986 _vo(vo), 2987 _failures(false), 2988 _hrclaimer(g1h->workers()->active_workers()) {} 2989 2990 bool failures() { 2991 return _failures; 2992 } 2993 2994 void work(uint worker_id) { 2995 HandleMark hm; 2996 VerifyRegionClosure blk(true, _vo); 2997 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer); 2998 if (blk.failures()) { 2999 _failures = true; 3000 } 3001 } 3002 }; 3003 3004 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3005 if (SafepointSynchronize::is_at_safepoint()) { 3006 assert(Thread::current()->is_VM_thread(), 3007 "Expected to be executed serially by the VM thread at this point"); 3008 3009 if (!silent) { gclog_or_tty->print("Roots "); } 3010 VerifyRootsClosure rootsCl(vo); 3011 VerifyKlassClosure klassCl(this, &rootsCl); 3012 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3013 3014 // We apply the relevant closures to all the oops in the 3015 // system dictionary, class loader data graph, the string table 3016 // and the nmethods in the code cache. 3017 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3018 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3019 3020 { 3021 G1RootProcessor root_processor(this); 3022 root_processor.process_all_roots(&rootsCl, 3023 &cldCl, 3024 &blobsCl); 3025 } 3026 3027 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3028 3029 if (vo != VerifyOption_G1UseMarkWord) { 3030 // If we're verifying during a full GC then the region sets 3031 // will have been torn down at the start of the GC. Therefore 3032 // verifying the region sets will fail. So we only verify 3033 // the region sets when not in a full GC. 3034 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3035 verify_region_sets(); 3036 } 3037 3038 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3039 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3040 3041 G1ParVerifyTask task(this, vo); 3042 assert(UseDynamicNumberOfGCThreads || 3043 workers()->active_workers() == workers()->total_workers(), 3044 "If not dynamic should be using all the workers"); 3045 uint n_workers = workers()->active_workers(); 3046 set_par_threads(n_workers); 3047 workers()->run_task(&task); 3048 set_par_threads(0); 3049 if (task.failures()) { 3050 failures = true; 3051 } 3052 3053 } else { 3054 VerifyRegionClosure blk(false, vo); 3055 heap_region_iterate(&blk); 3056 if (blk.failures()) { 3057 failures = true; 3058 } 3059 } 3060 3061 if (G1StringDedup::is_enabled()) { 3062 if (!silent) gclog_or_tty->print("StrDedup "); 3063 G1StringDedup::verify(); 3064 } 3065 3066 if (failures) { 3067 gclog_or_tty->print_cr("Heap:"); 3068 // It helps to have the per-region information in the output to 3069 // help us track down what went wrong. This is why we call 3070 // print_extended_on() instead of print_on(). 3071 print_extended_on(gclog_or_tty); 3072 gclog_or_tty->cr(); 3073 gclog_or_tty->flush(); 3074 } 3075 guarantee(!failures, "there should not have been any failures"); 3076 } else { 3077 if (!silent) { 3078 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3079 if (G1StringDedup::is_enabled()) { 3080 gclog_or_tty->print(", StrDedup"); 3081 } 3082 gclog_or_tty->print(") "); 3083 } 3084 } 3085 } 3086 3087 void G1CollectedHeap::verify(bool silent) { 3088 verify(silent, VerifyOption_G1UsePrevMarking); 3089 } 3090 3091 double G1CollectedHeap::verify(bool guard, const char* msg) { 3092 double verify_time_ms = 0.0; 3093 3094 if (guard && total_collections() >= VerifyGCStartAt) { 3095 double verify_start = os::elapsedTime(); 3096 HandleMark hm; // Discard invalid handles created during verification 3097 prepare_for_verify(); 3098 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3099 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3100 } 3101 3102 return verify_time_ms; 3103 } 3104 3105 void G1CollectedHeap::verify_before_gc() { 3106 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3107 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3108 } 3109 3110 void G1CollectedHeap::verify_after_gc() { 3111 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3112 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3113 } 3114 3115 class PrintRegionClosure: public HeapRegionClosure { 3116 outputStream* _st; 3117 public: 3118 PrintRegionClosure(outputStream* st) : _st(st) {} 3119 bool doHeapRegion(HeapRegion* r) { 3120 r->print_on(_st); 3121 return false; 3122 } 3123 }; 3124 3125 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3126 const HeapRegion* hr, 3127 const VerifyOption vo) const { 3128 switch (vo) { 3129 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3130 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3131 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3132 default: ShouldNotReachHere(); 3133 } 3134 return false; // keep some compilers happy 3135 } 3136 3137 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3138 const VerifyOption vo) const { 3139 switch (vo) { 3140 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3141 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3142 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3143 default: ShouldNotReachHere(); 3144 } 3145 return false; // keep some compilers happy 3146 } 3147 3148 void G1CollectedHeap::print_on(outputStream* st) const { 3149 st->print(" %-20s", "garbage-first heap"); 3150 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3151 capacity()/K, used_unlocked()/K); 3152 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")", 3153 p2i(_hrm.reserved().start()), 3154 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords), 3155 p2i(_hrm.reserved().end())); 3156 st->cr(); 3157 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3158 uint young_regions = _young_list->length(); 3159 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3160 (size_t) young_regions * HeapRegion::GrainBytes / K); 3161 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3162 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3163 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3164 st->cr(); 3165 MetaspaceAux::print_on(st); 3166 } 3167 3168 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3169 print_on(st); 3170 3171 // Print the per-region information. 3172 st->cr(); 3173 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3174 "HS=humongous(starts), HC=humongous(continues), " 3175 "CS=collection set, F=free, TS=gc time stamp, " 3176 "PTAMS=previous top-at-mark-start, " 3177 "NTAMS=next top-at-mark-start)"); 3178 PrintRegionClosure blk(st); 3179 heap_region_iterate(&blk); 3180 } 3181 3182 void G1CollectedHeap::print_on_error(outputStream* st) const { 3183 this->CollectedHeap::print_on_error(st); 3184 3185 if (_cm != NULL) { 3186 st->cr(); 3187 _cm->print_on_error(st); 3188 } 3189 } 3190 3191 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3192 workers()->print_worker_threads_on(st); 3193 _cmThread->print_on(st); 3194 st->cr(); 3195 _cm->print_worker_threads_on(st); 3196 _cg1r->print_worker_threads_on(st); 3197 if (G1StringDedup::is_enabled()) { 3198 G1StringDedup::print_worker_threads_on(st); 3199 } 3200 } 3201 3202 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3203 workers()->threads_do(tc); 3204 tc->do_thread(_cmThread); 3205 _cg1r->threads_do(tc); 3206 if (G1StringDedup::is_enabled()) { 3207 G1StringDedup::threads_do(tc); 3208 } 3209 } 3210 3211 void G1CollectedHeap::print_tracing_info() const { 3212 // We'll overload this to mean "trace GC pause statistics." 3213 if (TraceYoungGenTime || TraceOldGenTime) { 3214 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3215 // to that. 3216 g1_policy()->print_tracing_info(); 3217 } 3218 if (G1SummarizeRSetStats) { 3219 g1_rem_set()->print_summary_info(); 3220 } 3221 if (G1SummarizeConcMark) { 3222 concurrent_mark()->print_summary_info(); 3223 } 3224 g1_policy()->print_yg_surv_rate_info(); 3225 } 3226 3227 #ifndef PRODUCT 3228 // Helpful for debugging RSet issues. 3229 3230 class PrintRSetsClosure : public HeapRegionClosure { 3231 private: 3232 const char* _msg; 3233 size_t _occupied_sum; 3234 3235 public: 3236 bool doHeapRegion(HeapRegion* r) { 3237 HeapRegionRemSet* hrrs = r->rem_set(); 3238 size_t occupied = hrrs->occupied(); 3239 _occupied_sum += occupied; 3240 3241 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3242 HR_FORMAT_PARAMS(r)); 3243 if (occupied == 0) { 3244 gclog_or_tty->print_cr(" RSet is empty"); 3245 } else { 3246 hrrs->print(); 3247 } 3248 gclog_or_tty->print_cr("----------"); 3249 return false; 3250 } 3251 3252 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3253 gclog_or_tty->cr(); 3254 gclog_or_tty->print_cr("========================================"); 3255 gclog_or_tty->print_cr("%s", msg); 3256 gclog_or_tty->cr(); 3257 } 3258 3259 ~PrintRSetsClosure() { 3260 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3261 gclog_or_tty->print_cr("========================================"); 3262 gclog_or_tty->cr(); 3263 } 3264 }; 3265 3266 void G1CollectedHeap::print_cset_rsets() { 3267 PrintRSetsClosure cl("Printing CSet RSets"); 3268 collection_set_iterate(&cl); 3269 } 3270 3271 void G1CollectedHeap::print_all_rsets() { 3272 PrintRSetsClosure cl("Printing All RSets");; 3273 heap_region_iterate(&cl); 3274 } 3275 #endif // PRODUCT 3276 3277 G1CollectedHeap* G1CollectedHeap::heap() { 3278 CollectedHeap* heap = Universe::heap(); 3279 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 3280 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); 3281 return (G1CollectedHeap*)heap; 3282 } 3283 3284 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3285 // always_do_update_barrier = false; 3286 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3287 // Fill TLAB's and such 3288 accumulate_statistics_all_tlabs(); 3289 ensure_parsability(true); 3290 3291 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3292 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3293 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3294 } 3295 } 3296 3297 void G1CollectedHeap::gc_epilogue(bool full) { 3298 3299 if (G1SummarizeRSetStats && 3300 (G1SummarizeRSetStatsPeriod > 0) && 3301 // we are at the end of the GC. Total collections has already been increased. 3302 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3303 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3304 } 3305 3306 // FIXME: what is this about? 3307 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3308 // is set. 3309 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3310 "derived pointer present")); 3311 // always_do_update_barrier = true; 3312 3313 resize_all_tlabs(); 3314 allocation_context_stats().update(full); 3315 3316 // We have just completed a GC. Update the soft reference 3317 // policy with the new heap occupancy 3318 Universe::update_heap_info_at_gc(); 3319 } 3320 3321 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3322 uint gc_count_before, 3323 bool* succeeded, 3324 GCCause::Cause gc_cause) { 3325 assert_heap_not_locked_and_not_at_safepoint(); 3326 g1_policy()->record_stop_world_start(); 3327 VM_G1IncCollectionPause op(gc_count_before, 3328 word_size, 3329 false, /* should_initiate_conc_mark */ 3330 g1_policy()->max_pause_time_ms(), 3331 gc_cause); 3332 3333 op.set_allocation_context(AllocationContext::current()); 3334 VMThread::execute(&op); 3335 3336 HeapWord* result = op.result(); 3337 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3338 assert(result == NULL || ret_succeeded, 3339 "the result should be NULL if the VM did not succeed"); 3340 *succeeded = ret_succeeded; 3341 3342 assert_heap_not_locked(); 3343 return result; 3344 } 3345 3346 void 3347 G1CollectedHeap::doConcurrentMark() { 3348 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3349 if (!_cmThread->in_progress()) { 3350 _cmThread->set_started(); 3351 CGC_lock->notify(); 3352 } 3353 } 3354 3355 size_t G1CollectedHeap::pending_card_num() { 3356 size_t extra_cards = 0; 3357 JavaThread *curr = Threads::first(); 3358 while (curr != NULL) { 3359 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3360 extra_cards += dcq.size(); 3361 curr = curr->next(); 3362 } 3363 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3364 size_t buffer_size = dcqs.buffer_size(); 3365 size_t buffer_num = dcqs.completed_buffers_num(); 3366 3367 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3368 // in bytes - not the number of 'entries'. We need to convert 3369 // into a number of cards. 3370 return (buffer_size * buffer_num + extra_cards) / oopSize; 3371 } 3372 3373 size_t G1CollectedHeap::cards_scanned() { 3374 return g1_rem_set()->cardsScanned(); 3375 } 3376 3377 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3378 private: 3379 size_t _total_humongous; 3380 size_t _candidate_humongous; 3381 3382 DirtyCardQueue _dcq; 3383 3384 // We don't nominate objects with many remembered set entries, on 3385 // the assumption that such objects are likely still live. 3386 bool is_remset_small(HeapRegion* region) const { 3387 HeapRegionRemSet* const rset = region->rem_set(); 3388 return G1EagerReclaimHumongousObjectsWithStaleRefs 3389 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) 3390 : rset->is_empty(); 3391 } 3392 3393 bool is_typeArray_region(HeapRegion* region) const { 3394 return oop(region->bottom())->is_typeArray(); 3395 } 3396 3397 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { 3398 assert(region->is_starts_humongous(), "Must start a humongous object"); 3399 3400 // Candidate selection must satisfy the following constraints 3401 // while concurrent marking is in progress: 3402 // 3403 // * In order to maintain SATB invariants, an object must not be 3404 // reclaimed if it was allocated before the start of marking and 3405 // has not had its references scanned. Such an object must have 3406 // its references (including type metadata) scanned to ensure no 3407 // live objects are missed by the marking process. Objects 3408 // allocated after the start of concurrent marking don't need to 3409 // be scanned. 3410 // 3411 // * An object must not be reclaimed if it is on the concurrent 3412 // mark stack. Objects allocated after the start of concurrent 3413 // marking are never pushed on the mark stack. 3414 // 3415 // Nominating only objects allocated after the start of concurrent 3416 // marking is sufficient to meet both constraints. This may miss 3417 // some objects that satisfy the constraints, but the marking data 3418 // structures don't support efficiently performing the needed 3419 // additional tests or scrubbing of the mark stack. 3420 // 3421 // However, we presently only nominate is_typeArray() objects. 3422 // A humongous object containing references induces remembered 3423 // set entries on other regions. In order to reclaim such an 3424 // object, those remembered sets would need to be cleaned up. 3425 // 3426 // We also treat is_typeArray() objects specially, allowing them 3427 // to be reclaimed even if allocated before the start of 3428 // concurrent mark. For this we rely on mark stack insertion to 3429 // exclude is_typeArray() objects, preventing reclaiming an object 3430 // that is in the mark stack. We also rely on the metadata for 3431 // such objects to be built-in and so ensured to be kept live. 3432 // Frequent allocation and drop of large binary blobs is an 3433 // important use case for eager reclaim, and this special handling 3434 // may reduce needed headroom. 3435 3436 return is_typeArray_region(region) && is_remset_small(region); 3437 } 3438 3439 public: 3440 RegisterHumongousWithInCSetFastTestClosure() 3441 : _total_humongous(0), 3442 _candidate_humongous(0), 3443 _dcq(&JavaThread::dirty_card_queue_set()) { 3444 } 3445 3446 virtual bool doHeapRegion(HeapRegion* r) { 3447 if (!r->is_starts_humongous()) { 3448 return false; 3449 } 3450 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3451 3452 bool is_candidate = humongous_region_is_candidate(g1h, r); 3453 uint rindex = r->hrm_index(); 3454 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 3455 if (is_candidate) { 3456 _candidate_humongous++; 3457 g1h->register_humongous_region_with_cset(rindex); 3458 // Is_candidate already filters out humongous object with large remembered sets. 3459 // If we have a humongous object with a few remembered sets, we simply flush these 3460 // remembered set entries into the DCQS. That will result in automatic 3461 // re-evaluation of their remembered set entries during the following evacuation 3462 // phase. 3463 if (!r->rem_set()->is_empty()) { 3464 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 3465 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 3466 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 3467 HeapRegionRemSetIterator hrrs(r->rem_set()); 3468 size_t card_index; 3469 while (hrrs.has_next(card_index)) { 3470 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 3471 // The remembered set might contain references to already freed 3472 // regions. Filter out such entries to avoid failing card table 3473 // verification. 3474 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) { 3475 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 3476 *card_ptr = CardTableModRefBS::dirty_card_val(); 3477 _dcq.enqueue(card_ptr); 3478 } 3479 } 3480 } 3481 r->rem_set()->clear_locked(); 3482 } 3483 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 3484 } 3485 _total_humongous++; 3486 3487 return false; 3488 } 3489 3490 size_t total_humongous() const { return _total_humongous; } 3491 size_t candidate_humongous() const { return _candidate_humongous; } 3492 3493 void flush_rem_set_entries() { _dcq.flush(); } 3494 }; 3495 3496 void G1CollectedHeap::register_humongous_regions_with_cset() { 3497 if (!G1EagerReclaimHumongousObjects) { 3498 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 3499 return; 3500 } 3501 double time = os::elapsed_counter(); 3502 3503 // Collect reclaim candidate information and register candidates with cset. 3504 RegisterHumongousWithInCSetFastTestClosure cl; 3505 heap_region_iterate(&cl); 3506 3507 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 3508 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 3509 cl.total_humongous(), 3510 cl.candidate_humongous()); 3511 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3512 3513 // Finally flush all remembered set entries to re-check into the global DCQS. 3514 cl.flush_rem_set_entries(); 3515 } 3516 3517 void 3518 G1CollectedHeap::setup_surviving_young_words() { 3519 assert(_surviving_young_words == NULL, "pre-condition"); 3520 uint array_length = g1_policy()->young_cset_region_length(); 3521 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3522 if (_surviving_young_words == NULL) { 3523 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3524 "Not enough space for young surv words summary."); 3525 } 3526 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3527 #ifdef ASSERT 3528 for (uint i = 0; i < array_length; ++i) { 3529 assert( _surviving_young_words[i] == 0, "memset above" ); 3530 } 3531 #endif // !ASSERT 3532 } 3533 3534 void 3535 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3536 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3537 uint array_length = g1_policy()->young_cset_region_length(); 3538 for (uint i = 0; i < array_length; ++i) { 3539 _surviving_young_words[i] += surv_young_words[i]; 3540 } 3541 } 3542 3543 void 3544 G1CollectedHeap::cleanup_surviving_young_words() { 3545 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3546 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words); 3547 _surviving_young_words = NULL; 3548 } 3549 3550 #ifdef ASSERT 3551 class VerifyCSetClosure: public HeapRegionClosure { 3552 public: 3553 bool doHeapRegion(HeapRegion* hr) { 3554 // Here we check that the CSet region's RSet is ready for parallel 3555 // iteration. The fields that we'll verify are only manipulated 3556 // when the region is part of a CSet and is collected. Afterwards, 3557 // we reset these fields when we clear the region's RSet (when the 3558 // region is freed) so they are ready when the region is 3559 // re-allocated. The only exception to this is if there's an 3560 // evacuation failure and instead of freeing the region we leave 3561 // it in the heap. In that case, we reset these fields during 3562 // evacuation failure handling. 3563 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3564 3565 // Here's a good place to add any other checks we'd like to 3566 // perform on CSet regions. 3567 return false; 3568 } 3569 }; 3570 #endif // ASSERT 3571 3572 #if TASKQUEUE_STATS 3573 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3574 st->print_raw_cr("GC Task Stats"); 3575 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3576 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3577 } 3578 3579 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3580 print_taskqueue_stats_hdr(st); 3581 3582 TaskQueueStats totals; 3583 const uint n = workers()->total_workers(); 3584 for (uint i = 0; i < n; ++i) { 3585 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 3586 totals += task_queue(i)->stats; 3587 } 3588 st->print_raw("tot "); totals.print(st); st->cr(); 3589 3590 DEBUG_ONLY(totals.verify()); 3591 } 3592 3593 void G1CollectedHeap::reset_taskqueue_stats() { 3594 const uint n = workers()->total_workers(); 3595 for (uint i = 0; i < n; ++i) { 3596 task_queue(i)->stats.reset(); 3597 } 3598 } 3599 #endif // TASKQUEUE_STATS 3600 3601 void G1CollectedHeap::log_gc_header() { 3602 if (!G1Log::fine()) { 3603 return; 3604 } 3605 3606 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id()); 3607 3608 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3609 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)") 3610 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3611 3612 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3613 } 3614 3615 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3616 if (!G1Log::fine()) { 3617 return; 3618 } 3619 3620 if (G1Log::finer()) { 3621 if (evacuation_failed()) { 3622 gclog_or_tty->print(" (to-space exhausted)"); 3623 } 3624 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3625 g1_policy()->phase_times()->note_gc_end(); 3626 g1_policy()->phase_times()->print(pause_time_sec); 3627 g1_policy()->print_detailed_heap_transition(); 3628 } else { 3629 if (evacuation_failed()) { 3630 gclog_or_tty->print("--"); 3631 } 3632 g1_policy()->print_heap_transition(); 3633 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3634 } 3635 gclog_or_tty->flush(); 3636 } 3637 3638 bool 3639 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3640 assert_at_safepoint(true /* should_be_vm_thread */); 3641 guarantee(!is_gc_active(), "collection is not reentrant"); 3642 3643 if (GC_locker::check_active_before_gc()) { 3644 return false; 3645 } 3646 3647 _gc_timer_stw->register_gc_start(); 3648 3649 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3650 3651 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3652 ResourceMark rm; 3653 3654 G1Log::update_level(); 3655 print_heap_before_gc(); 3656 trace_heap_before_gc(_gc_tracer_stw); 3657 3658 verify_region_sets_optional(); 3659 verify_dirty_young_regions(); 3660 3661 // This call will decide whether this pause is an initial-mark 3662 // pause. If it is, during_initial_mark_pause() will return true 3663 // for the duration of this pause. 3664 g1_policy()->decide_on_conc_mark_initiation(); 3665 3666 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3667 assert(!collector_state()->during_initial_mark_pause() || 3668 collector_state()->gcs_are_young(), "sanity"); 3669 3670 // We also do not allow mixed GCs during marking. 3671 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity"); 3672 3673 // Record whether this pause is an initial mark. When the current 3674 // thread has completed its logging output and it's safe to signal 3675 // the CM thread, the flag's value in the policy has been reset. 3676 bool should_start_conc_mark = collector_state()->during_initial_mark_pause(); 3677 3678 // Inner scope for scope based logging, timers, and stats collection 3679 { 3680 EvacuationInfo evacuation_info; 3681 3682 if (collector_state()->during_initial_mark_pause()) { 3683 // We are about to start a marking cycle, so we increment the 3684 // full collection counter. 3685 increment_old_marking_cycles_started(); 3686 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3687 } 3688 3689 _gc_tracer_stw->report_yc_type(yc_type()); 3690 3691 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3692 3693 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 3694 workers()->active_workers(), 3695 Threads::number_of_non_daemon_threads()); 3696 assert(UseDynamicNumberOfGCThreads || 3697 active_workers == workers()->total_workers(), 3698 "If not dynamic should be using all the workers"); 3699 workers()->set_active_workers(active_workers); 3700 3701 double pause_start_sec = os::elapsedTime(); 3702 g1_policy()->phase_times()->note_gc_start(active_workers, collector_state()->mark_in_progress()); 3703 log_gc_header(); 3704 3705 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3706 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3707 3708 // If the secondary_free_list is not empty, append it to the 3709 // free_list. No need to wait for the cleanup operation to finish; 3710 // the region allocation code will check the secondary_free_list 3711 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3712 // set, skip this step so that the region allocation code has to 3713 // get entries from the secondary_free_list. 3714 if (!G1StressConcRegionFreeing) { 3715 append_secondary_free_list_if_not_empty_with_lock(); 3716 } 3717 3718 assert(check_young_list_well_formed(), "young list should be well formed"); 3719 3720 // Don't dynamically change the number of GC threads this early. A value of 3721 // 0 is used to indicate serial work. When parallel work is done, 3722 // it will be set. 3723 3724 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3725 IsGCActiveMark x; 3726 3727 gc_prologue(false); 3728 increment_total_collections(false /* full gc */); 3729 increment_gc_time_stamp(); 3730 3731 verify_before_gc(); 3732 3733 check_bitmaps("GC Start"); 3734 3735 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3736 3737 // Please see comment in g1CollectedHeap.hpp and 3738 // G1CollectedHeap::ref_processing_init() to see how 3739 // reference processing currently works in G1. 3740 3741 // Enable discovery in the STW reference processor 3742 ref_processor_stw()->enable_discovery(); 3743 3744 { 3745 // We want to temporarily turn off discovery by the 3746 // CM ref processor, if necessary, and turn it back on 3747 // on again later if we do. Using a scoped 3748 // NoRefDiscovery object will do this. 3749 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3750 3751 // Forget the current alloc region (we might even choose it to be part 3752 // of the collection set!). 3753 _allocator->release_mutator_alloc_region(); 3754 3755 // We should call this after we retire the mutator alloc 3756 // region(s) so that all the ALLOC / RETIRE events are generated 3757 // before the start GC event. 3758 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3759 3760 // This timing is only used by the ergonomics to handle our pause target. 3761 // It is unclear why this should not include the full pause. We will 3762 // investigate this in CR 7178365. 3763 // 3764 // Preserving the old comment here if that helps the investigation: 3765 // 3766 // The elapsed time induced by the start time below deliberately elides 3767 // the possible verification above. 3768 double sample_start_time_sec = os::elapsedTime(); 3769 3770 #if YOUNG_LIST_VERBOSE 3771 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 3772 _young_list->print(); 3773 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3774 #endif // YOUNG_LIST_VERBOSE 3775 3776 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3777 3778 double scan_wait_start = os::elapsedTime(); 3779 // We have to wait until the CM threads finish scanning the 3780 // root regions as it's the only way to ensure that all the 3781 // objects on them have been correctly scanned before we start 3782 // moving them during the GC. 3783 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3784 double wait_time_ms = 0.0; 3785 if (waited) { 3786 double scan_wait_end = os::elapsedTime(); 3787 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3788 } 3789 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3790 3791 #if YOUNG_LIST_VERBOSE 3792 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 3793 _young_list->print(); 3794 #endif // YOUNG_LIST_VERBOSE 3795 3796 if (collector_state()->during_initial_mark_pause()) { 3797 concurrent_mark()->checkpointRootsInitialPre(); 3798 } 3799 3800 #if YOUNG_LIST_VERBOSE 3801 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 3802 _young_list->print(); 3803 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3804 #endif // YOUNG_LIST_VERBOSE 3805 3806 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 3807 3808 register_humongous_regions_with_cset(); 3809 3810 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3811 3812 _cm->note_start_of_gc(); 3813 // We call this after finalize_cset() to 3814 // ensure that the CSet has been finalized. 3815 _cm->verify_no_cset_oops(); 3816 3817 if (_hr_printer.is_active()) { 3818 HeapRegion* hr = g1_policy()->collection_set(); 3819 while (hr != NULL) { 3820 _hr_printer.cset(hr); 3821 hr = hr->next_in_collection_set(); 3822 } 3823 } 3824 3825 #ifdef ASSERT 3826 VerifyCSetClosure cl; 3827 collection_set_iterate(&cl); 3828 #endif // ASSERT 3829 3830 setup_surviving_young_words(); 3831 3832 // Initialize the GC alloc regions. 3833 _allocator->init_gc_alloc_regions(evacuation_info); 3834 3835 // Actually do the work... 3836 evacuate_collection_set(evacuation_info); 3837 3838 free_collection_set(g1_policy()->collection_set(), evacuation_info); 3839 3840 eagerly_reclaim_humongous_regions(); 3841 3842 g1_policy()->clear_collection_set(); 3843 3844 cleanup_surviving_young_words(); 3845 3846 // Start a new incremental collection set for the next pause. 3847 g1_policy()->start_incremental_cset_building(); 3848 3849 clear_cset_fast_test(); 3850 3851 _young_list->reset_sampled_info(); 3852 3853 // Don't check the whole heap at this point as the 3854 // GC alloc regions from this pause have been tagged 3855 // as survivors and moved on to the survivor list. 3856 // Survivor regions will fail the !is_young() check. 3857 assert(check_young_list_empty(false /* check_heap */), 3858 "young list should be empty"); 3859 3860 #if YOUNG_LIST_VERBOSE 3861 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 3862 _young_list->print(); 3863 #endif // YOUNG_LIST_VERBOSE 3864 3865 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 3866 _young_list->first_survivor_region(), 3867 _young_list->last_survivor_region()); 3868 3869 _young_list->reset_auxilary_lists(); 3870 3871 if (evacuation_failed()) { 3872 _allocator->set_used(recalculate_used()); 3873 uint n_queues = MAX2((int)ParallelGCThreads, 1); 3874 for (uint i = 0; i < n_queues; i++) { 3875 if (_evacuation_failed_info_array[i].has_failed()) { 3876 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3877 } 3878 } 3879 } else { 3880 // The "used" of the the collection set have already been subtracted 3881 // when they were freed. Add in the bytes evacuated. 3882 _allocator->increase_used(g1_policy()->bytes_copied_during_gc()); 3883 } 3884 3885 if (collector_state()->during_initial_mark_pause()) { 3886 // We have to do this before we notify the CM threads that 3887 // they can start working to make sure that all the 3888 // appropriate initialization is done on the CM object. 3889 concurrent_mark()->checkpointRootsInitialPost(); 3890 collector_state()->set_mark_in_progress(true); 3891 // Note that we don't actually trigger the CM thread at 3892 // this point. We do that later when we're sure that 3893 // the current thread has completed its logging output. 3894 } 3895 3896 allocate_dummy_regions(); 3897 3898 #if YOUNG_LIST_VERBOSE 3899 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 3900 _young_list->print(); 3901 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3902 #endif // YOUNG_LIST_VERBOSE 3903 3904 _allocator->init_mutator_alloc_region(); 3905 3906 { 3907 size_t expand_bytes = g1_policy()->expansion_amount(); 3908 if (expand_bytes > 0) { 3909 size_t bytes_before = capacity(); 3910 // No need for an ergo verbose message here, 3911 // expansion_amount() does this when it returns a value > 0. 3912 if (!expand(expand_bytes)) { 3913 // We failed to expand the heap. Cannot do anything about it. 3914 } 3915 } 3916 } 3917 3918 // We redo the verification but now wrt to the new CSet which 3919 // has just got initialized after the previous CSet was freed. 3920 _cm->verify_no_cset_oops(); 3921 _cm->note_end_of_gc(); 3922 3923 // This timing is only used by the ergonomics to handle our pause target. 3924 // It is unclear why this should not include the full pause. We will 3925 // investigate this in CR 7178365. 3926 double sample_end_time_sec = os::elapsedTime(); 3927 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3928 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 3929 3930 MemoryService::track_memory_usage(); 3931 3932 // In prepare_for_verify() below we'll need to scan the deferred 3933 // update buffers to bring the RSets up-to-date if 3934 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 3935 // the update buffers we'll probably need to scan cards on the 3936 // regions we just allocated to (i.e., the GC alloc 3937 // regions). However, during the last GC we called 3938 // set_saved_mark() on all the GC alloc regions, so card 3939 // scanning might skip the [saved_mark_word()...top()] area of 3940 // those regions (i.e., the area we allocated objects into 3941 // during the last GC). But it shouldn't. Given that 3942 // saved_mark_word() is conditional on whether the GC time stamp 3943 // on the region is current or not, by incrementing the GC time 3944 // stamp here we invalidate all the GC time stamps on all the 3945 // regions and saved_mark_word() will simply return top() for 3946 // all the regions. This is a nicer way of ensuring this rather 3947 // than iterating over the regions and fixing them. In fact, the 3948 // GC time stamp increment here also ensures that 3949 // saved_mark_word() will return top() between pauses, i.e., 3950 // during concurrent refinement. So we don't need the 3951 // is_gc_active() check to decided which top to use when 3952 // scanning cards (see CR 7039627). 3953 increment_gc_time_stamp(); 3954 3955 verify_after_gc(); 3956 check_bitmaps("GC End"); 3957 3958 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 3959 ref_processor_stw()->verify_no_references_recorded(); 3960 3961 // CM reference discovery will be re-enabled if necessary. 3962 } 3963 3964 // We should do this after we potentially expand the heap so 3965 // that all the COMMIT events are generated before the end GC 3966 // event, and after we retire the GC alloc regions so that all 3967 // RETIRE events are generated before the end GC event. 3968 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 3969 3970 #ifdef TRACESPINNING 3971 ParallelTaskTerminator::print_termination_counts(); 3972 #endif 3973 3974 gc_epilogue(false); 3975 } 3976 3977 // Print the remainder of the GC log output. 3978 log_gc_footer(os::elapsedTime() - pause_start_sec); 3979 3980 // It is not yet to safe to tell the concurrent mark to 3981 // start as we have some optional output below. We don't want the 3982 // output from the concurrent mark thread interfering with this 3983 // logging output either. 3984 3985 _hrm.verify_optional(); 3986 verify_region_sets_optional(); 3987 3988 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats()); 3989 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3990 3991 print_heap_after_gc(); 3992 trace_heap_after_gc(_gc_tracer_stw); 3993 3994 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3995 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3996 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3997 // before any GC notifications are raised. 3998 g1mm()->update_sizes(); 3999 4000 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4001 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4002 _gc_timer_stw->register_gc_end(); 4003 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4004 } 4005 // It should now be safe to tell the concurrent mark thread to start 4006 // without its logging output interfering with the logging output 4007 // that came from the pause. 4008 4009 if (should_start_conc_mark) { 4010 // CAUTION: after the doConcurrentMark() call below, 4011 // the concurrent marking thread(s) could be running 4012 // concurrently with us. Make sure that anything after 4013 // this point does not assume that we are the only GC thread 4014 // running. Note: of course, the actual marking work will 4015 // not start until the safepoint itself is released in 4016 // SuspendibleThreadSet::desynchronize(). 4017 doConcurrentMark(); 4018 } 4019 4020 return true; 4021 } 4022 4023 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4024 _drain_in_progress = false; 4025 set_evac_failure_closure(cl); 4026 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4027 } 4028 4029 void G1CollectedHeap::finalize_for_evac_failure() { 4030 assert(_evac_failure_scan_stack != NULL && 4031 _evac_failure_scan_stack->length() == 0, 4032 "Postcondition"); 4033 assert(!_drain_in_progress, "Postcondition"); 4034 delete _evac_failure_scan_stack; 4035 _evac_failure_scan_stack = NULL; 4036 } 4037 4038 void G1CollectedHeap::remove_self_forwarding_pointers() { 4039 double remove_self_forwards_start = os::elapsedTime(); 4040 4041 set_par_threads(); 4042 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4043 workers()->run_task(&rsfp_task); 4044 set_par_threads(0); 4045 4046 // Now restore saved marks, if any. 4047 assert(_objs_with_preserved_marks.size() == 4048 _preserved_marks_of_objs.size(), "Both or none."); 4049 while (!_objs_with_preserved_marks.is_empty()) { 4050 oop obj = _objs_with_preserved_marks.pop(); 4051 markOop m = _preserved_marks_of_objs.pop(); 4052 obj->set_mark(m); 4053 } 4054 _objs_with_preserved_marks.clear(true); 4055 _preserved_marks_of_objs.clear(true); 4056 4057 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4058 } 4059 4060 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4061 _evac_failure_scan_stack->push(obj); 4062 } 4063 4064 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4065 assert(_evac_failure_scan_stack != NULL, "precondition"); 4066 4067 while (_evac_failure_scan_stack->length() > 0) { 4068 oop obj = _evac_failure_scan_stack->pop(); 4069 _evac_failure_closure->set_region(heap_region_containing(obj)); 4070 obj->oop_iterate_backwards(_evac_failure_closure); 4071 } 4072 } 4073 4074 oop 4075 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4076 oop old) { 4077 assert(obj_in_cs(old), 4078 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4079 p2i(old))); 4080 markOop m = old->mark(); 4081 oop forward_ptr = old->forward_to_atomic(old); 4082 if (forward_ptr == NULL) { 4083 // Forward-to-self succeeded. 4084 assert(_par_scan_state != NULL, "par scan state"); 4085 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4086 uint queue_num = _par_scan_state->queue_num(); 4087 4088 _evacuation_failed = true; 4089 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4090 if (_evac_failure_closure != cl) { 4091 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4092 assert(!_drain_in_progress, 4093 "Should only be true while someone holds the lock."); 4094 // Set the global evac-failure closure to the current thread's. 4095 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4096 set_evac_failure_closure(cl); 4097 // Now do the common part. 4098 handle_evacuation_failure_common(old, m); 4099 // Reset to NULL. 4100 set_evac_failure_closure(NULL); 4101 } else { 4102 // The lock is already held, and this is recursive. 4103 assert(_drain_in_progress, "This should only be the recursive case."); 4104 handle_evacuation_failure_common(old, m); 4105 } 4106 return old; 4107 } else { 4108 // Forward-to-self failed. Either someone else managed to allocate 4109 // space for this object (old != forward_ptr) or they beat us in 4110 // self-forwarding it (old == forward_ptr). 4111 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4112 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4113 "should not be in the CSet", 4114 p2i(old), p2i(forward_ptr))); 4115 return forward_ptr; 4116 } 4117 } 4118 4119 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4120 preserve_mark_if_necessary(old, m); 4121 4122 HeapRegion* r = heap_region_containing(old); 4123 if (!r->evacuation_failed()) { 4124 r->set_evacuation_failed(true); 4125 _hr_printer.evac_failure(r); 4126 } 4127 4128 push_on_evac_failure_scan_stack(old); 4129 4130 if (!_drain_in_progress) { 4131 // prevent recursion in copy_to_survivor_space() 4132 _drain_in_progress = true; 4133 drain_evac_failure_scan_stack(); 4134 _drain_in_progress = false; 4135 } 4136 } 4137 4138 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4139 assert(evacuation_failed(), "Oversaving!"); 4140 // We want to call the "for_promotion_failure" version only in the 4141 // case of a promotion failure. 4142 if (m->must_be_preserved_for_promotion_failure(obj)) { 4143 _objs_with_preserved_marks.push(obj); 4144 _preserved_marks_of_objs.push(m); 4145 } 4146 } 4147 4148 void G1ParCopyHelper::mark_object(oop obj) { 4149 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); 4150 4151 // We know that the object is not moving so it's safe to read its size. 4152 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4153 } 4154 4155 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4156 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4157 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4158 assert(from_obj != to_obj, "should not be self-forwarded"); 4159 4160 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); 4161 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); 4162 4163 // The object might be in the process of being copied by another 4164 // worker so we cannot trust that its to-space image is 4165 // well-formed. So we have to read its size from its from-space 4166 // image which we know should not be changing. 4167 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4168 } 4169 4170 template <class T> 4171 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4172 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4173 _scanned_klass->record_modified_oops(); 4174 } 4175 } 4176 4177 template <G1Barrier barrier, G1Mark do_mark_object> 4178 template <class T> 4179 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4180 T heap_oop = oopDesc::load_heap_oop(p); 4181 4182 if (oopDesc::is_null(heap_oop)) { 4183 return; 4184 } 4185 4186 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4187 4188 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4189 4190 const InCSetState state = _g1->in_cset_state(obj); 4191 if (state.is_in_cset()) { 4192 oop forwardee; 4193 markOop m = obj->mark(); 4194 if (m->is_marked()) { 4195 forwardee = (oop) m->decode_pointer(); 4196 } else { 4197 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m); 4198 } 4199 assert(forwardee != NULL, "forwardee should not be NULL"); 4200 oopDesc::encode_store_heap_oop(p, forwardee); 4201 if (do_mark_object != G1MarkNone && forwardee != obj) { 4202 // If the object is self-forwarded we don't need to explicitly 4203 // mark it, the evacuation failure protocol will do so. 4204 mark_forwarded_object(obj, forwardee); 4205 } 4206 4207 if (barrier == G1BarrierKlass) { 4208 do_klass_barrier(p, forwardee); 4209 } 4210 } else { 4211 if (state.is_humongous()) { 4212 _g1->set_humongous_is_live(obj); 4213 } 4214 // The object is not in collection set. If we're a root scanning 4215 // closure during an initial mark pause then attempt to mark the object. 4216 if (do_mark_object == G1MarkFromRoot) { 4217 mark_object(obj); 4218 } 4219 } 4220 4221 if (barrier == G1BarrierEvac) { 4222 _par_scan_state->update_rs(_from, p, _worker_id); 4223 } 4224 } 4225 4226 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p); 4227 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p); 4228 4229 class G1ParEvacuateFollowersClosure : public VoidClosure { 4230 protected: 4231 G1CollectedHeap* _g1h; 4232 G1ParScanThreadState* _par_scan_state; 4233 RefToScanQueueSet* _queues; 4234 ParallelTaskTerminator* _terminator; 4235 4236 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4237 RefToScanQueueSet* queues() { return _queues; } 4238 ParallelTaskTerminator* terminator() { return _terminator; } 4239 4240 public: 4241 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4242 G1ParScanThreadState* par_scan_state, 4243 RefToScanQueueSet* queues, 4244 ParallelTaskTerminator* terminator) 4245 : _g1h(g1h), _par_scan_state(par_scan_state), 4246 _queues(queues), _terminator(terminator) {} 4247 4248 void do_void(); 4249 4250 private: 4251 inline bool offer_termination(); 4252 }; 4253 4254 bool G1ParEvacuateFollowersClosure::offer_termination() { 4255 G1ParScanThreadState* const pss = par_scan_state(); 4256 pss->start_term_time(); 4257 const bool res = terminator()->offer_termination(); 4258 pss->end_term_time(); 4259 return res; 4260 } 4261 4262 void G1ParEvacuateFollowersClosure::do_void() { 4263 G1ParScanThreadState* const pss = par_scan_state(); 4264 pss->trim_queue(); 4265 do { 4266 pss->steal_and_trim_queue(queues()); 4267 } while (!offer_termination()); 4268 } 4269 4270 class G1KlassScanClosure : public KlassClosure { 4271 G1ParCopyHelper* _closure; 4272 bool _process_only_dirty; 4273 int _count; 4274 public: 4275 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4276 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4277 void do_klass(Klass* klass) { 4278 // If the klass has not been dirtied we know that there's 4279 // no references into the young gen and we can skip it. 4280 if (!_process_only_dirty || klass->has_modified_oops()) { 4281 // Clean the klass since we're going to scavenge all the metadata. 4282 klass->clear_modified_oops(); 4283 4284 // Tell the closure that this klass is the Klass to scavenge 4285 // and is the one to dirty if oops are left pointing into the young gen. 4286 _closure->set_scanned_klass(klass); 4287 4288 klass->oops_do(_closure); 4289 4290 _closure->set_scanned_klass(NULL); 4291 } 4292 _count++; 4293 } 4294 }; 4295 4296 class G1ParTask : public AbstractGangTask { 4297 protected: 4298 G1CollectedHeap* _g1h; 4299 RefToScanQueueSet *_queues; 4300 G1RootProcessor* _root_processor; 4301 ParallelTaskTerminator _terminator; 4302 uint _n_workers; 4303 4304 Mutex _stats_lock; 4305 Mutex* stats_lock() { return &_stats_lock; } 4306 4307 public: 4308 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor) 4309 : AbstractGangTask("G1 collection"), 4310 _g1h(g1h), 4311 _queues(task_queues), 4312 _root_processor(root_processor), 4313 _terminator(0, _queues), 4314 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4315 {} 4316 4317 RefToScanQueueSet* queues() { return _queues; } 4318 4319 RefToScanQueue *work_queue(int i) { 4320 return queues()->queue(i); 4321 } 4322 4323 ParallelTaskTerminator* terminator() { return &_terminator; } 4324 4325 virtual void set_for_termination(uint active_workers) { 4326 _root_processor->set_num_workers(active_workers); 4327 terminator()->reset_for_reuse(active_workers); 4328 _n_workers = active_workers; 4329 } 4330 4331 // Helps out with CLD processing. 4332 // 4333 // During InitialMark we need to: 4334 // 1) Scavenge all CLDs for the young GC. 4335 // 2) Mark all objects directly reachable from strong CLDs. 4336 template <G1Mark do_mark_object> 4337 class G1CLDClosure : public CLDClosure { 4338 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure; 4339 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure; 4340 G1KlassScanClosure _klass_in_cld_closure; 4341 bool _claim; 4342 4343 public: 4344 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure, 4345 bool only_young, bool claim) 4346 : _oop_closure(oop_closure), 4347 _oop_in_klass_closure(oop_closure->g1(), 4348 oop_closure->pss(), 4349 oop_closure->rp()), 4350 _klass_in_cld_closure(&_oop_in_klass_closure, only_young), 4351 _claim(claim) { 4352 4353 } 4354 4355 void do_cld(ClassLoaderData* cld) { 4356 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim); 4357 } 4358 }; 4359 4360 void work(uint worker_id) { 4361 if (worker_id >= _n_workers) return; // no work needed this round 4362 4363 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime()); 4364 4365 { 4366 ResourceMark rm; 4367 HandleMark hm; 4368 4369 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4370 4371 G1ParScanThreadState pss(_g1h, worker_id, rp); 4372 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 4373 4374 pss.set_evac_failure_closure(&evac_failure_cl); 4375 4376 bool only_young = _g1h->collector_state()->gcs_are_young(); 4377 4378 // Non-IM young GC. 4379 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp); 4380 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl, 4381 only_young, // Only process dirty klasses. 4382 false); // No need to claim CLDs. 4383 // IM young GC. 4384 // Strong roots closures. 4385 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp); 4386 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl, 4387 false, // Process all klasses. 4388 true); // Need to claim CLDs. 4389 // Weak roots closures. 4390 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp); 4391 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl, 4392 false, // Process all klasses. 4393 true); // Need to claim CLDs. 4394 4395 OopClosure* strong_root_cl; 4396 OopClosure* weak_root_cl; 4397 CLDClosure* strong_cld_cl; 4398 CLDClosure* weak_cld_cl; 4399 4400 bool trace_metadata = false; 4401 4402 if (_g1h->collector_state()->during_initial_mark_pause()) { 4403 // We also need to mark copied objects. 4404 strong_root_cl = &scan_mark_root_cl; 4405 strong_cld_cl = &scan_mark_cld_cl; 4406 if (ClassUnloadingWithConcurrentMark) { 4407 weak_root_cl = &scan_mark_weak_root_cl; 4408 weak_cld_cl = &scan_mark_weak_cld_cl; 4409 trace_metadata = true; 4410 } else { 4411 weak_root_cl = &scan_mark_root_cl; 4412 weak_cld_cl = &scan_mark_cld_cl; 4413 } 4414 } else { 4415 strong_root_cl = &scan_only_root_cl; 4416 weak_root_cl = &scan_only_root_cl; 4417 strong_cld_cl = &scan_only_cld_cl; 4418 weak_cld_cl = &scan_only_cld_cl; 4419 } 4420 4421 pss.start_strong_roots(); 4422 4423 _root_processor->evacuate_roots(strong_root_cl, 4424 weak_root_cl, 4425 strong_cld_cl, 4426 weak_cld_cl, 4427 trace_metadata, 4428 worker_id); 4429 4430 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4431 _root_processor->scan_remembered_sets(&push_heap_rs_cl, 4432 weak_root_cl, 4433 worker_id); 4434 pss.end_strong_roots(); 4435 4436 { 4437 double start = os::elapsedTime(); 4438 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4439 evac.do_void(); 4440 double elapsed_sec = os::elapsedTime() - start; 4441 double term_sec = pss.term_time(); 4442 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 4443 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 4444 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts()); 4445 } 4446 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4447 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4448 4449 if (PrintTerminationStats) { 4450 MutexLocker x(stats_lock()); 4451 pss.print_termination_stats(worker_id); 4452 } 4453 4454 assert(pss.queue_is_empty(), "should be empty"); 4455 4456 // Close the inner scope so that the ResourceMark and HandleMark 4457 // destructors are executed here and are included as part of the 4458 // "GC Worker Time". 4459 } 4460 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 4461 } 4462 }; 4463 4464 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4465 private: 4466 BoolObjectClosure* _is_alive; 4467 int _initial_string_table_size; 4468 int _initial_symbol_table_size; 4469 4470 bool _process_strings; 4471 int _strings_processed; 4472 int _strings_removed; 4473 4474 bool _process_symbols; 4475 int _symbols_processed; 4476 int _symbols_removed; 4477 4478 public: 4479 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4480 AbstractGangTask("String/Symbol Unlinking"), 4481 _is_alive(is_alive), 4482 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4483 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4484 4485 _initial_string_table_size = StringTable::the_table()->table_size(); 4486 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4487 if (process_strings) { 4488 StringTable::clear_parallel_claimed_index(); 4489 } 4490 if (process_symbols) { 4491 SymbolTable::clear_parallel_claimed_index(); 4492 } 4493 } 4494 4495 ~G1StringSymbolTableUnlinkTask() { 4496 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4497 err_msg("claim value %d after unlink less than initial string table size %d", 4498 StringTable::parallel_claimed_index(), _initial_string_table_size)); 4499 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4500 err_msg("claim value %d after unlink less than initial symbol table size %d", 4501 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 4502 4503 if (G1TraceStringSymbolTableScrubbing) { 4504 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4505 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 4506 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 4507 strings_processed(), strings_removed(), 4508 symbols_processed(), symbols_removed()); 4509 } 4510 } 4511 4512 void work(uint worker_id) { 4513 int strings_processed = 0; 4514 int strings_removed = 0; 4515 int symbols_processed = 0; 4516 int symbols_removed = 0; 4517 if (_process_strings) { 4518 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4519 Atomic::add(strings_processed, &_strings_processed); 4520 Atomic::add(strings_removed, &_strings_removed); 4521 } 4522 if (_process_symbols) { 4523 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 4524 Atomic::add(symbols_processed, &_symbols_processed); 4525 Atomic::add(symbols_removed, &_symbols_removed); 4526 } 4527 } 4528 4529 size_t strings_processed() const { return (size_t)_strings_processed; } 4530 size_t strings_removed() const { return (size_t)_strings_removed; } 4531 4532 size_t symbols_processed() const { return (size_t)_symbols_processed; } 4533 size_t symbols_removed() const { return (size_t)_symbols_removed; } 4534 }; 4535 4536 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 4537 private: 4538 static Monitor* _lock; 4539 4540 BoolObjectClosure* const _is_alive; 4541 const bool _unloading_occurred; 4542 const uint _num_workers; 4543 4544 // Variables used to claim nmethods. 4545 nmethod* _first_nmethod; 4546 volatile nmethod* _claimed_nmethod; 4547 4548 // The list of nmethods that need to be processed by the second pass. 4549 volatile nmethod* _postponed_list; 4550 volatile uint _num_entered_barrier; 4551 4552 public: 4553 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 4554 _is_alive(is_alive), 4555 _unloading_occurred(unloading_occurred), 4556 _num_workers(num_workers), 4557 _first_nmethod(NULL), 4558 _claimed_nmethod(NULL), 4559 _postponed_list(NULL), 4560 _num_entered_barrier(0) 4561 { 4562 nmethod::increase_unloading_clock(); 4563 // Get first alive nmethod 4564 NMethodIterator iter = NMethodIterator(); 4565 if(iter.next_alive()) { 4566 _first_nmethod = iter.method(); 4567 } 4568 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 4569 } 4570 4571 ~G1CodeCacheUnloadingTask() { 4572 CodeCache::verify_clean_inline_caches(); 4573 4574 CodeCache::set_needs_cache_clean(false); 4575 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 4576 4577 CodeCache::verify_icholder_relocations(); 4578 } 4579 4580 private: 4581 void add_to_postponed_list(nmethod* nm) { 4582 nmethod* old; 4583 do { 4584 old = (nmethod*)_postponed_list; 4585 nm->set_unloading_next(old); 4586 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 4587 } 4588 4589 void clean_nmethod(nmethod* nm) { 4590 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 4591 4592 if (postponed) { 4593 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 4594 add_to_postponed_list(nm); 4595 } 4596 4597 // Mark that this thread has been cleaned/unloaded. 4598 // After this call, it will be safe to ask if this nmethod was unloaded or not. 4599 nm->set_unloading_clock(nmethod::global_unloading_clock()); 4600 } 4601 4602 void clean_nmethod_postponed(nmethod* nm) { 4603 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 4604 } 4605 4606 static const int MaxClaimNmethods = 16; 4607 4608 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 4609 nmethod* first; 4610 NMethodIterator last; 4611 4612 do { 4613 *num_claimed_nmethods = 0; 4614 4615 first = (nmethod*)_claimed_nmethod; 4616 last = NMethodIterator(first); 4617 4618 if (first != NULL) { 4619 4620 for (int i = 0; i < MaxClaimNmethods; i++) { 4621 if (!last.next_alive()) { 4622 break; 4623 } 4624 claimed_nmethods[i] = last.method(); 4625 (*num_claimed_nmethods)++; 4626 } 4627 } 4628 4629 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 4630 } 4631 4632 nmethod* claim_postponed_nmethod() { 4633 nmethod* claim; 4634 nmethod* next; 4635 4636 do { 4637 claim = (nmethod*)_postponed_list; 4638 if (claim == NULL) { 4639 return NULL; 4640 } 4641 4642 next = claim->unloading_next(); 4643 4644 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 4645 4646 return claim; 4647 } 4648 4649 public: 4650 // Mark that we're done with the first pass of nmethod cleaning. 4651 void barrier_mark(uint worker_id) { 4652 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4653 _num_entered_barrier++; 4654 if (_num_entered_barrier == _num_workers) { 4655 ml.notify_all(); 4656 } 4657 } 4658 4659 // See if we have to wait for the other workers to 4660 // finish their first-pass nmethod cleaning work. 4661 void barrier_wait(uint worker_id) { 4662 if (_num_entered_barrier < _num_workers) { 4663 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4664 while (_num_entered_barrier < _num_workers) { 4665 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 4666 } 4667 } 4668 } 4669 4670 // Cleaning and unloading of nmethods. Some work has to be postponed 4671 // to the second pass, when we know which nmethods survive. 4672 void work_first_pass(uint worker_id) { 4673 // The first nmethods is claimed by the first worker. 4674 if (worker_id == 0 && _first_nmethod != NULL) { 4675 clean_nmethod(_first_nmethod); 4676 _first_nmethod = NULL; 4677 } 4678 4679 int num_claimed_nmethods; 4680 nmethod* claimed_nmethods[MaxClaimNmethods]; 4681 4682 while (true) { 4683 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 4684 4685 if (num_claimed_nmethods == 0) { 4686 break; 4687 } 4688 4689 for (int i = 0; i < num_claimed_nmethods; i++) { 4690 clean_nmethod(claimed_nmethods[i]); 4691 } 4692 } 4693 } 4694 4695 void work_second_pass(uint worker_id) { 4696 nmethod* nm; 4697 // Take care of postponed nmethods. 4698 while ((nm = claim_postponed_nmethod()) != NULL) { 4699 clean_nmethod_postponed(nm); 4700 } 4701 } 4702 }; 4703 4704 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 4705 4706 class G1KlassCleaningTask : public StackObj { 4707 BoolObjectClosure* _is_alive; 4708 volatile jint _clean_klass_tree_claimed; 4709 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 4710 4711 public: 4712 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 4713 _is_alive(is_alive), 4714 _clean_klass_tree_claimed(0), 4715 _klass_iterator() { 4716 } 4717 4718 private: 4719 bool claim_clean_klass_tree_task() { 4720 if (_clean_klass_tree_claimed) { 4721 return false; 4722 } 4723 4724 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 4725 } 4726 4727 InstanceKlass* claim_next_klass() { 4728 Klass* klass; 4729 do { 4730 klass =_klass_iterator.next_klass(); 4731 } while (klass != NULL && !klass->oop_is_instance()); 4732 4733 return (InstanceKlass*)klass; 4734 } 4735 4736 public: 4737 4738 void clean_klass(InstanceKlass* ik) { 4739 ik->clean_implementors_list(_is_alive); 4740 ik->clean_method_data(_is_alive); 4741 4742 // G1 specific cleanup work that has 4743 // been moved here to be done in parallel. 4744 ik->clean_dependent_nmethods(); 4745 } 4746 4747 void work() { 4748 ResourceMark rm; 4749 4750 // One worker will clean the subklass/sibling klass tree. 4751 if (claim_clean_klass_tree_task()) { 4752 Klass::clean_subklass_tree(_is_alive); 4753 } 4754 4755 // All workers will help cleaning the classes, 4756 InstanceKlass* klass; 4757 while ((klass = claim_next_klass()) != NULL) { 4758 clean_klass(klass); 4759 } 4760 } 4761 }; 4762 4763 // To minimize the remark pause times, the tasks below are done in parallel. 4764 class G1ParallelCleaningTask : public AbstractGangTask { 4765 private: 4766 G1StringSymbolTableUnlinkTask _string_symbol_task; 4767 G1CodeCacheUnloadingTask _code_cache_task; 4768 G1KlassCleaningTask _klass_cleaning_task; 4769 4770 public: 4771 // The constructor is run in the VMThread. 4772 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 4773 AbstractGangTask("Parallel Cleaning"), 4774 _string_symbol_task(is_alive, process_strings, process_symbols), 4775 _code_cache_task(num_workers, is_alive, unloading_occurred), 4776 _klass_cleaning_task(is_alive) { 4777 } 4778 4779 // The parallel work done by all worker threads. 4780 void work(uint worker_id) { 4781 // Do first pass of code cache cleaning. 4782 _code_cache_task.work_first_pass(worker_id); 4783 4784 // Let the threads mark that the first pass is done. 4785 _code_cache_task.barrier_mark(worker_id); 4786 4787 // Clean the Strings and Symbols. 4788 _string_symbol_task.work(worker_id); 4789 4790 // Wait for all workers to finish the first code cache cleaning pass. 4791 _code_cache_task.barrier_wait(worker_id); 4792 4793 // Do the second code cache cleaning work, which realize on 4794 // the liveness information gathered during the first pass. 4795 _code_cache_task.work_second_pass(worker_id); 4796 4797 // Clean all klasses that were not unloaded. 4798 _klass_cleaning_task.work(); 4799 } 4800 }; 4801 4802 4803 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 4804 bool process_strings, 4805 bool process_symbols, 4806 bool class_unloading_occurred) { 4807 uint n_workers = workers()->active_workers(); 4808 4809 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 4810 n_workers, class_unloading_occurred); 4811 set_par_threads(n_workers); 4812 workers()->run_task(&g1_unlink_task); 4813 set_par_threads(0); 4814 } 4815 4816 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 4817 bool process_strings, bool process_symbols) { 4818 { 4819 uint n_workers = workers()->active_workers(); 4820 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 4821 set_par_threads(n_workers); 4822 workers()->run_task(&g1_unlink_task); 4823 set_par_threads(0); 4824 } 4825 4826 if (G1StringDedup::is_enabled()) { 4827 G1StringDedup::unlink(is_alive); 4828 } 4829 } 4830 4831 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 4832 private: 4833 DirtyCardQueueSet* _queue; 4834 public: 4835 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 4836 4837 virtual void work(uint worker_id) { 4838 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4839 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 4840 4841 RedirtyLoggedCardTableEntryClosure cl; 4842 _queue->par_apply_closure_to_all_completed_buffers(&cl); 4843 4844 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed()); 4845 } 4846 }; 4847 4848 void G1CollectedHeap::redirty_logged_cards() { 4849 double redirty_logged_cards_start = os::elapsedTime(); 4850 4851 uint n_workers = workers()->active_workers(); 4852 4853 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 4854 dirty_card_queue_set().reset_for_par_iteration(); 4855 set_par_threads(n_workers); 4856 workers()->run_task(&redirty_task); 4857 set_par_threads(0); 4858 4859 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 4860 dcq.merge_bufferlists(&dirty_card_queue_set()); 4861 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 4862 4863 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 4864 } 4865 4866 // Weak Reference Processing support 4867 4868 // An always "is_alive" closure that is used to preserve referents. 4869 // If the object is non-null then it's alive. Used in the preservation 4870 // of referent objects that are pointed to by reference objects 4871 // discovered by the CM ref processor. 4872 class G1AlwaysAliveClosure: public BoolObjectClosure { 4873 G1CollectedHeap* _g1; 4874 public: 4875 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4876 bool do_object_b(oop p) { 4877 if (p != NULL) { 4878 return true; 4879 } 4880 return false; 4881 } 4882 }; 4883 4884 bool G1STWIsAliveClosure::do_object_b(oop p) { 4885 // An object is reachable if it is outside the collection set, 4886 // or is inside and copied. 4887 return !_g1->obj_in_cs(p) || p->is_forwarded(); 4888 } 4889 4890 // Non Copying Keep Alive closure 4891 class G1KeepAliveClosure: public OopClosure { 4892 G1CollectedHeap* _g1; 4893 public: 4894 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4895 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 4896 void do_oop(oop* p) { 4897 oop obj = *p; 4898 assert(obj != NULL, "the caller should have filtered out NULL values"); 4899 4900 const InCSetState cset_state = _g1->in_cset_state(obj); 4901 if (!cset_state.is_in_cset_or_humongous()) { 4902 return; 4903 } 4904 if (cset_state.is_in_cset()) { 4905 assert( obj->is_forwarded(), "invariant" ); 4906 *p = obj->forwardee(); 4907 } else { 4908 assert(!obj->is_forwarded(), "invariant" ); 4909 assert(cset_state.is_humongous(), 4910 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value())); 4911 _g1->set_humongous_is_live(obj); 4912 } 4913 } 4914 }; 4915 4916 // Copying Keep Alive closure - can be called from both 4917 // serial and parallel code as long as different worker 4918 // threads utilize different G1ParScanThreadState instances 4919 // and different queues. 4920 4921 class G1CopyingKeepAliveClosure: public OopClosure { 4922 G1CollectedHeap* _g1h; 4923 OopClosure* _copy_non_heap_obj_cl; 4924 G1ParScanThreadState* _par_scan_state; 4925 4926 public: 4927 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 4928 OopClosure* non_heap_obj_cl, 4929 G1ParScanThreadState* pss): 4930 _g1h(g1h), 4931 _copy_non_heap_obj_cl(non_heap_obj_cl), 4932 _par_scan_state(pss) 4933 {} 4934 4935 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 4936 virtual void do_oop( oop* p) { do_oop_work(p); } 4937 4938 template <class T> void do_oop_work(T* p) { 4939 oop obj = oopDesc::load_decode_heap_oop(p); 4940 4941 if (_g1h->is_in_cset_or_humongous(obj)) { 4942 // If the referent object has been forwarded (either copied 4943 // to a new location or to itself in the event of an 4944 // evacuation failure) then we need to update the reference 4945 // field and, if both reference and referent are in the G1 4946 // heap, update the RSet for the referent. 4947 // 4948 // If the referent has not been forwarded then we have to keep 4949 // it alive by policy. Therefore we have copy the referent. 4950 // 4951 // If the reference field is in the G1 heap then we can push 4952 // on the PSS queue. When the queue is drained (after each 4953 // phase of reference processing) the object and it's followers 4954 // will be copied, the reference field set to point to the 4955 // new location, and the RSet updated. Otherwise we need to 4956 // use the the non-heap or metadata closures directly to copy 4957 // the referent object and update the pointer, while avoiding 4958 // updating the RSet. 4959 4960 if (_g1h->is_in_g1_reserved(p)) { 4961 _par_scan_state->push_on_queue(p); 4962 } else { 4963 assert(!Metaspace::contains((const void*)p), 4964 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p))); 4965 _copy_non_heap_obj_cl->do_oop(p); 4966 } 4967 } 4968 } 4969 }; 4970 4971 // Serial drain queue closure. Called as the 'complete_gc' 4972 // closure for each discovered list in some of the 4973 // reference processing phases. 4974 4975 class G1STWDrainQueueClosure: public VoidClosure { 4976 protected: 4977 G1CollectedHeap* _g1h; 4978 G1ParScanThreadState* _par_scan_state; 4979 4980 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4981 4982 public: 4983 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 4984 _g1h(g1h), 4985 _par_scan_state(pss) 4986 { } 4987 4988 void do_void() { 4989 G1ParScanThreadState* const pss = par_scan_state(); 4990 pss->trim_queue(); 4991 } 4992 }; 4993 4994 // Parallel Reference Processing closures 4995 4996 // Implementation of AbstractRefProcTaskExecutor for parallel reference 4997 // processing during G1 evacuation pauses. 4998 4999 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5000 private: 5001 G1CollectedHeap* _g1h; 5002 RefToScanQueueSet* _queues; 5003 FlexibleWorkGang* _workers; 5004 uint _active_workers; 5005 5006 public: 5007 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5008 FlexibleWorkGang* workers, 5009 RefToScanQueueSet *task_queues, 5010 uint n_workers) : 5011 _g1h(g1h), 5012 _queues(task_queues), 5013 _workers(workers), 5014 _active_workers(n_workers) 5015 { 5016 assert(n_workers > 0, "shouldn't call this otherwise"); 5017 } 5018 5019 // Executes the given task using concurrent marking worker threads. 5020 virtual void execute(ProcessTask& task); 5021 virtual void execute(EnqueueTask& task); 5022 }; 5023 5024 // Gang task for possibly parallel reference processing 5025 5026 class G1STWRefProcTaskProxy: public AbstractGangTask { 5027 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5028 ProcessTask& _proc_task; 5029 G1CollectedHeap* _g1h; 5030 RefToScanQueueSet *_task_queues; 5031 ParallelTaskTerminator* _terminator; 5032 5033 public: 5034 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5035 G1CollectedHeap* g1h, 5036 RefToScanQueueSet *task_queues, 5037 ParallelTaskTerminator* terminator) : 5038 AbstractGangTask("Process reference objects in parallel"), 5039 _proc_task(proc_task), 5040 _g1h(g1h), 5041 _task_queues(task_queues), 5042 _terminator(terminator) 5043 {} 5044 5045 virtual void work(uint worker_id) { 5046 // The reference processing task executed by a single worker. 5047 ResourceMark rm; 5048 HandleMark hm; 5049 5050 G1STWIsAliveClosure is_alive(_g1h); 5051 5052 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5053 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5054 5055 pss.set_evac_failure_closure(&evac_failure_cl); 5056 5057 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5058 5059 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5060 5061 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5062 5063 if (_g1h->collector_state()->during_initial_mark_pause()) { 5064 // We also need to mark copied objects. 5065 copy_non_heap_cl = ©_mark_non_heap_cl; 5066 } 5067 5068 // Keep alive closure. 5069 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5070 5071 // Complete GC closure 5072 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5073 5074 // Call the reference processing task's work routine. 5075 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5076 5077 // Note we cannot assert that the refs array is empty here as not all 5078 // of the processing tasks (specifically phase2 - pp2_work) execute 5079 // the complete_gc closure (which ordinarily would drain the queue) so 5080 // the queue may not be empty. 5081 } 5082 }; 5083 5084 // Driver routine for parallel reference processing. 5085 // Creates an instance of the ref processing gang 5086 // task and has the worker threads execute it. 5087 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5088 assert(_workers != NULL, "Need parallel worker threads."); 5089 5090 ParallelTaskTerminator terminator(_active_workers, _queues); 5091 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5092 5093 _g1h->set_par_threads(_active_workers); 5094 _workers->run_task(&proc_task_proxy); 5095 _g1h->set_par_threads(0); 5096 } 5097 5098 // Gang task for parallel reference enqueueing. 5099 5100 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5101 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5102 EnqueueTask& _enq_task; 5103 5104 public: 5105 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5106 AbstractGangTask("Enqueue reference objects in parallel"), 5107 _enq_task(enq_task) 5108 { } 5109 5110 virtual void work(uint worker_id) { 5111 _enq_task.work(worker_id); 5112 } 5113 }; 5114 5115 // Driver routine for parallel reference enqueueing. 5116 // Creates an instance of the ref enqueueing gang 5117 // task and has the worker threads execute it. 5118 5119 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5120 assert(_workers != NULL, "Need parallel worker threads."); 5121 5122 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5123 5124 _g1h->set_par_threads(_active_workers); 5125 _workers->run_task(&enq_task_proxy); 5126 _g1h->set_par_threads(0); 5127 } 5128 5129 // End of weak reference support closures 5130 5131 // Abstract task used to preserve (i.e. copy) any referent objects 5132 // that are in the collection set and are pointed to by reference 5133 // objects discovered by the CM ref processor. 5134 5135 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5136 protected: 5137 G1CollectedHeap* _g1h; 5138 RefToScanQueueSet *_queues; 5139 ParallelTaskTerminator _terminator; 5140 uint _n_workers; 5141 5142 public: 5143 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, uint workers, RefToScanQueueSet *task_queues) : 5144 AbstractGangTask("ParPreserveCMReferents"), 5145 _g1h(g1h), 5146 _queues(task_queues), 5147 _terminator(workers, _queues), 5148 _n_workers(workers) 5149 { } 5150 5151 void work(uint worker_id) { 5152 ResourceMark rm; 5153 HandleMark hm; 5154 5155 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5156 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5157 5158 pss.set_evac_failure_closure(&evac_failure_cl); 5159 5160 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5161 5162 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5163 5164 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5165 5166 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5167 5168 if (_g1h->collector_state()->during_initial_mark_pause()) { 5169 // We also need to mark copied objects. 5170 copy_non_heap_cl = ©_mark_non_heap_cl; 5171 } 5172 5173 // Is alive closure 5174 G1AlwaysAliveClosure always_alive(_g1h); 5175 5176 // Copying keep alive closure. Applied to referent objects that need 5177 // to be copied. 5178 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5179 5180 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5181 5182 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5183 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5184 5185 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5186 // So this must be true - but assert just in case someone decides to 5187 // change the worker ids. 5188 assert(worker_id < limit, "sanity"); 5189 assert(!rp->discovery_is_atomic(), "check this code"); 5190 5191 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5192 for (uint idx = worker_id; idx < limit; idx += stride) { 5193 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5194 5195 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5196 while (iter.has_next()) { 5197 // Since discovery is not atomic for the CM ref processor, we 5198 // can see some null referent objects. 5199 iter.load_ptrs(DEBUG_ONLY(true)); 5200 oop ref = iter.obj(); 5201 5202 // This will filter nulls. 5203 if (iter.is_referent_alive()) { 5204 iter.make_referent_alive(); 5205 } 5206 iter.move_to_next(); 5207 } 5208 } 5209 5210 // Drain the queue - which may cause stealing 5211 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5212 drain_queue.do_void(); 5213 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5214 assert(pss.queue_is_empty(), "should be"); 5215 } 5216 }; 5217 5218 // Weak Reference processing during an evacuation pause (part 1). 5219 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5220 double ref_proc_start = os::elapsedTime(); 5221 5222 ReferenceProcessor* rp = _ref_processor_stw; 5223 assert(rp->discovery_enabled(), "should have been enabled"); 5224 5225 // Any reference objects, in the collection set, that were 'discovered' 5226 // by the CM ref processor should have already been copied (either by 5227 // applying the external root copy closure to the discovered lists, or 5228 // by following an RSet entry). 5229 // 5230 // But some of the referents, that are in the collection set, that these 5231 // reference objects point to may not have been copied: the STW ref 5232 // processor would have seen that the reference object had already 5233 // been 'discovered' and would have skipped discovering the reference, 5234 // but would not have treated the reference object as a regular oop. 5235 // As a result the copy closure would not have been applied to the 5236 // referent object. 5237 // 5238 // We need to explicitly copy these referent objects - the references 5239 // will be processed at the end of remarking. 5240 // 5241 // We also need to do this copying before we process the reference 5242 // objects discovered by the STW ref processor in case one of these 5243 // referents points to another object which is also referenced by an 5244 // object discovered by the STW ref processor. 5245 5246 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers"); 5247 5248 set_par_threads(no_of_gc_workers); 5249 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5250 no_of_gc_workers, 5251 _task_queues); 5252 5253 workers()->run_task(&keep_cm_referents); 5254 5255 set_par_threads(0); 5256 5257 // Closure to test whether a referent is alive. 5258 G1STWIsAliveClosure is_alive(this); 5259 5260 // Even when parallel reference processing is enabled, the processing 5261 // of JNI refs is serial and performed serially by the current thread 5262 // rather than by a worker. The following PSS will be used for processing 5263 // JNI refs. 5264 5265 // Use only a single queue for this PSS. 5266 G1ParScanThreadState pss(this, 0, NULL); 5267 5268 // We do not embed a reference processor in the copying/scanning 5269 // closures while we're actually processing the discovered 5270 // reference objects. 5271 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5272 5273 pss.set_evac_failure_closure(&evac_failure_cl); 5274 5275 assert(pss.queue_is_empty(), "pre-condition"); 5276 5277 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5278 5279 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5280 5281 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5282 5283 if (collector_state()->during_initial_mark_pause()) { 5284 // We also need to mark copied objects. 5285 copy_non_heap_cl = ©_mark_non_heap_cl; 5286 } 5287 5288 // Keep alive closure. 5289 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss); 5290 5291 // Serial Complete GC closure 5292 G1STWDrainQueueClosure drain_queue(this, &pss); 5293 5294 // Setup the soft refs policy... 5295 rp->setup_policy(false); 5296 5297 ReferenceProcessorStats stats; 5298 if (!rp->processing_is_mt()) { 5299 // Serial reference processing... 5300 stats = rp->process_discovered_references(&is_alive, 5301 &keep_alive, 5302 &drain_queue, 5303 NULL, 5304 _gc_timer_stw, 5305 _gc_tracer_stw->gc_id()); 5306 } else { 5307 // Parallel reference processing 5308 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5309 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5310 5311 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5312 stats = rp->process_discovered_references(&is_alive, 5313 &keep_alive, 5314 &drain_queue, 5315 &par_task_executor, 5316 _gc_timer_stw, 5317 _gc_tracer_stw->gc_id()); 5318 } 5319 5320 _gc_tracer_stw->report_gc_reference_stats(stats); 5321 5322 // We have completed copying any necessary live referent objects. 5323 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5324 5325 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5326 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5327 } 5328 5329 // Weak Reference processing during an evacuation pause (part 2). 5330 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5331 double ref_enq_start = os::elapsedTime(); 5332 5333 ReferenceProcessor* rp = _ref_processor_stw; 5334 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5335 5336 // Now enqueue any remaining on the discovered lists on to 5337 // the pending list. 5338 if (!rp->processing_is_mt()) { 5339 // Serial reference processing... 5340 rp->enqueue_discovered_references(); 5341 } else { 5342 // Parallel reference enqueueing 5343 5344 assert(no_of_gc_workers == workers()->active_workers(), 5345 "Need to reset active workers"); 5346 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5347 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5348 5349 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5350 rp->enqueue_discovered_references(&par_task_executor); 5351 } 5352 5353 rp->verify_no_references_recorded(); 5354 assert(!rp->discovery_enabled(), "should have been disabled"); 5355 5356 // FIXME 5357 // CM's reference processing also cleans up the string and symbol tables. 5358 // Should we do that here also? We could, but it is a serial operation 5359 // and could significantly increase the pause time. 5360 5361 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5362 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5363 } 5364 5365 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5366 _expand_heap_after_alloc_failure = true; 5367 _evacuation_failed = false; 5368 5369 // Should G1EvacuationFailureALot be in effect for this GC? 5370 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5371 5372 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5373 5374 // Disable the hot card cache. 5375 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5376 hot_card_cache->reset_hot_cache_claimed_index(); 5377 hot_card_cache->set_use_cache(false); 5378 5379 const uint n_workers = workers()->active_workers(); 5380 assert(UseDynamicNumberOfGCThreads || 5381 n_workers == workers()->total_workers(), 5382 "If not dynamic should be using all the workers"); 5383 set_par_threads(n_workers); 5384 5385 5386 init_for_evac_failure(NULL); 5387 5388 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5389 double start_par_time_sec = os::elapsedTime(); 5390 double end_par_time_sec; 5391 5392 { 5393 G1RootProcessor root_processor(this); 5394 G1ParTask g1_par_task(this, _task_queues, &root_processor); 5395 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5396 if (collector_state()->during_initial_mark_pause()) { 5397 ClassLoaderDataGraph::clear_claimed_marks(); 5398 } 5399 5400 // The individual threads will set their evac-failure closures. 5401 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr(); 5402 // These tasks use ShareHeap::_process_strong_tasks 5403 assert(UseDynamicNumberOfGCThreads || 5404 workers()->active_workers() == workers()->total_workers(), 5405 "If not dynamic should be using all the workers"); 5406 workers()->run_task(&g1_par_task); 5407 end_par_time_sec = os::elapsedTime(); 5408 5409 // Closing the inner scope will execute the destructor 5410 // for the G1RootProcessor object. We record the current 5411 // elapsed time before closing the scope so that time 5412 // taken for the destructor is NOT included in the 5413 // reported parallel time. 5414 } 5415 5416 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 5417 5418 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5419 phase_times->record_par_time(par_time_ms); 5420 5421 double code_root_fixup_time_ms = 5422 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5423 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 5424 5425 set_par_threads(0); 5426 5427 // Process any discovered reference objects - we have 5428 // to do this _before_ we retire the GC alloc regions 5429 // as we may have to copy some 'reachable' referent 5430 // objects (and their reachable sub-graphs) that were 5431 // not copied during the pause. 5432 process_discovered_references(n_workers); 5433 5434 if (G1StringDedup::is_enabled()) { 5435 double fixup_start = os::elapsedTime(); 5436 5437 G1STWIsAliveClosure is_alive(this); 5438 G1KeepAliveClosure keep_alive(this); 5439 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times); 5440 5441 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 5442 phase_times->record_string_dedup_fixup_time(fixup_time_ms); 5443 } 5444 5445 _allocator->release_gc_alloc_regions(n_workers, evacuation_info); 5446 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5447 5448 // Reset and re-enable the hot card cache. 5449 // Note the counts for the cards in the regions in the 5450 // collection set are reset when the collection set is freed. 5451 hot_card_cache->reset_hot_cache(); 5452 hot_card_cache->set_use_cache(true); 5453 5454 purge_code_root_memory(); 5455 5456 finalize_for_evac_failure(); 5457 5458 if (evacuation_failed()) { 5459 remove_self_forwarding_pointers(); 5460 5461 // Reset the G1EvacuationFailureALot counters and flags 5462 // Note: the values are reset only when an actual 5463 // evacuation failure occurs. 5464 NOT_PRODUCT(reset_evacuation_should_fail();) 5465 } 5466 5467 // Enqueue any remaining references remaining on the STW 5468 // reference processor's discovered lists. We need to do 5469 // this after the card table is cleaned (and verified) as 5470 // the act of enqueueing entries on to the pending list 5471 // will log these updates (and dirty their associated 5472 // cards). We need these updates logged to update any 5473 // RSets. 5474 enqueue_discovered_references(n_workers); 5475 5476 redirty_logged_cards(); 5477 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5478 } 5479 5480 void G1CollectedHeap::free_region(HeapRegion* hr, 5481 FreeRegionList* free_list, 5482 bool par, 5483 bool locked) { 5484 assert(!hr->is_free(), "the region should not be free"); 5485 assert(!hr->is_empty(), "the region should not be empty"); 5486 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 5487 assert(free_list != NULL, "pre-condition"); 5488 5489 if (G1VerifyBitmaps) { 5490 MemRegion mr(hr->bottom(), hr->end()); 5491 concurrent_mark()->clearRangePrevBitmap(mr); 5492 } 5493 5494 // Clear the card counts for this region. 5495 // Note: we only need to do this if the region is not young 5496 // (since we don't refine cards in young regions). 5497 if (!hr->is_young()) { 5498 _cg1r->hot_card_cache()->reset_card_counts(hr); 5499 } 5500 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5501 free_list->add_ordered(hr); 5502 } 5503 5504 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5505 FreeRegionList* free_list, 5506 bool par) { 5507 assert(hr->is_starts_humongous(), "this is only for starts humongous regions"); 5508 assert(free_list != NULL, "pre-condition"); 5509 5510 size_t hr_capacity = hr->capacity(); 5511 // We need to read this before we make the region non-humongous, 5512 // otherwise the information will be gone. 5513 uint last_index = hr->last_hc_index(); 5514 hr->clear_humongous(); 5515 free_region(hr, free_list, par); 5516 5517 uint i = hr->hrm_index() + 1; 5518 while (i < last_index) { 5519 HeapRegion* curr_hr = region_at(i); 5520 assert(curr_hr->is_continues_humongous(), "invariant"); 5521 curr_hr->clear_humongous(); 5522 free_region(curr_hr, free_list, par); 5523 i += 1; 5524 } 5525 } 5526 5527 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 5528 const HeapRegionSetCount& humongous_regions_removed) { 5529 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5530 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5531 _old_set.bulk_remove(old_regions_removed); 5532 _humongous_set.bulk_remove(humongous_regions_removed); 5533 } 5534 5535 } 5536 5537 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 5538 assert(list != NULL, "list can't be null"); 5539 if (!list->is_empty()) { 5540 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5541 _hrm.insert_list_into_free_list(list); 5542 } 5543 } 5544 5545 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 5546 _allocator->decrease_used(bytes); 5547 } 5548 5549 class G1ParCleanupCTTask : public AbstractGangTask { 5550 G1SATBCardTableModRefBS* _ct_bs; 5551 G1CollectedHeap* _g1h; 5552 HeapRegion* volatile _su_head; 5553 public: 5554 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 5555 G1CollectedHeap* g1h) : 5556 AbstractGangTask("G1 Par Cleanup CT Task"), 5557 _ct_bs(ct_bs), _g1h(g1h) { } 5558 5559 void work(uint worker_id) { 5560 HeapRegion* r; 5561 while (r = _g1h->pop_dirty_cards_region()) { 5562 clear_cards(r); 5563 } 5564 } 5565 5566 void clear_cards(HeapRegion* r) { 5567 // Cards of the survivors should have already been dirtied. 5568 if (!r->is_survivor()) { 5569 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5570 } 5571 } 5572 }; 5573 5574 #ifndef PRODUCT 5575 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5576 G1CollectedHeap* _g1h; 5577 G1SATBCardTableModRefBS* _ct_bs; 5578 public: 5579 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 5580 : _g1h(g1h), _ct_bs(ct_bs) { } 5581 virtual bool doHeapRegion(HeapRegion* r) { 5582 if (r->is_survivor()) { 5583 _g1h->verify_dirty_region(r); 5584 } else { 5585 _g1h->verify_not_dirty_region(r); 5586 } 5587 return false; 5588 } 5589 }; 5590 5591 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5592 // All of the region should be clean. 5593 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5594 MemRegion mr(hr->bottom(), hr->end()); 5595 ct_bs->verify_not_dirty_region(mr); 5596 } 5597 5598 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5599 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5600 // dirty allocated blocks as they allocate them. The thread that 5601 // retires each region and replaces it with a new one will do a 5602 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5603 // not dirty that area (one less thing to have to do while holding 5604 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5605 // is dirty. 5606 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5607 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5608 if (hr->is_young()) { 5609 ct_bs->verify_g1_young_region(mr); 5610 } else { 5611 ct_bs->verify_dirty_region(mr); 5612 } 5613 } 5614 5615 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5616 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5617 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5618 verify_dirty_region(hr); 5619 } 5620 } 5621 5622 void G1CollectedHeap::verify_dirty_young_regions() { 5623 verify_dirty_young_list(_young_list->first_region()); 5624 } 5625 5626 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 5627 HeapWord* tams, HeapWord* end) { 5628 guarantee(tams <= end, 5629 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, p2i(tams), p2i(end))); 5630 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 5631 if (result < end) { 5632 gclog_or_tty->cr(); 5633 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT, 5634 bitmap_name, p2i(result)); 5635 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT, 5636 bitmap_name, p2i(tams), p2i(end)); 5637 return false; 5638 } 5639 return true; 5640 } 5641 5642 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 5643 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 5644 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 5645 5646 HeapWord* bottom = hr->bottom(); 5647 HeapWord* ptams = hr->prev_top_at_mark_start(); 5648 HeapWord* ntams = hr->next_top_at_mark_start(); 5649 HeapWord* end = hr->end(); 5650 5651 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 5652 5653 bool res_n = true; 5654 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 5655 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 5656 // if we happen to be in that state. 5657 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) { 5658 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 5659 } 5660 if (!res_p || !res_n) { 5661 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT, 5662 HR_FORMAT_PARAMS(hr)); 5663 gclog_or_tty->print_cr("#### Caller: %s", caller); 5664 return false; 5665 } 5666 return true; 5667 } 5668 5669 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 5670 if (!G1VerifyBitmaps) return; 5671 5672 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 5673 } 5674 5675 class G1VerifyBitmapClosure : public HeapRegionClosure { 5676 private: 5677 const char* _caller; 5678 G1CollectedHeap* _g1h; 5679 bool _failures; 5680 5681 public: 5682 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 5683 _caller(caller), _g1h(g1h), _failures(false) { } 5684 5685 bool failures() { return _failures; } 5686 5687 virtual bool doHeapRegion(HeapRegion* hr) { 5688 if (hr->is_continues_humongous()) return false; 5689 5690 bool result = _g1h->verify_bitmaps(_caller, hr); 5691 if (!result) { 5692 _failures = true; 5693 } 5694 return false; 5695 } 5696 }; 5697 5698 void G1CollectedHeap::check_bitmaps(const char* caller) { 5699 if (!G1VerifyBitmaps) return; 5700 5701 G1VerifyBitmapClosure cl(caller, this); 5702 heap_region_iterate(&cl); 5703 guarantee(!cl.failures(), "bitmap verification"); 5704 } 5705 5706 class G1CheckCSetFastTableClosure : public HeapRegionClosure { 5707 private: 5708 bool _failures; 5709 public: 5710 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { } 5711 5712 virtual bool doHeapRegion(HeapRegion* hr) { 5713 uint i = hr->hrm_index(); 5714 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i); 5715 if (hr->is_humongous()) { 5716 if (hr->in_collection_set()) { 5717 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i); 5718 _failures = true; 5719 return true; 5720 } 5721 if (cset_state.is_in_cset()) { 5722 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i); 5723 _failures = true; 5724 return true; 5725 } 5726 if (hr->is_continues_humongous() && cset_state.is_humongous()) { 5727 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i); 5728 _failures = true; 5729 return true; 5730 } 5731 } else { 5732 if (cset_state.is_humongous()) { 5733 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i); 5734 _failures = true; 5735 return true; 5736 } 5737 if (hr->in_collection_set() != cset_state.is_in_cset()) { 5738 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u", 5739 hr->in_collection_set(), cset_state.value(), i); 5740 _failures = true; 5741 return true; 5742 } 5743 if (cset_state.is_in_cset()) { 5744 if (hr->is_young() != (cset_state.is_young())) { 5745 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u", 5746 hr->is_young(), cset_state.value(), i); 5747 _failures = true; 5748 return true; 5749 } 5750 if (hr->is_old() != (cset_state.is_old())) { 5751 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u", 5752 hr->is_old(), cset_state.value(), i); 5753 _failures = true; 5754 return true; 5755 } 5756 } 5757 } 5758 return false; 5759 } 5760 5761 bool failures() const { return _failures; } 5762 }; 5763 5764 bool G1CollectedHeap::check_cset_fast_test() { 5765 G1CheckCSetFastTableClosure cl; 5766 _hrm.iterate(&cl); 5767 return !cl.failures(); 5768 } 5769 #endif // PRODUCT 5770 5771 void G1CollectedHeap::cleanUpCardTable() { 5772 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5773 double start = os::elapsedTime(); 5774 5775 { 5776 // Iterate over the dirty cards region list. 5777 G1ParCleanupCTTask cleanup_task(ct_bs, this); 5778 5779 set_par_threads(); 5780 workers()->run_task(&cleanup_task); 5781 set_par_threads(0); 5782 #ifndef PRODUCT 5783 if (G1VerifyCTCleanup || VerifyAfterGC) { 5784 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 5785 heap_region_iterate(&cleanup_verifier); 5786 } 5787 #endif 5788 } 5789 5790 double elapsed = os::elapsedTime() - start; 5791 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 5792 } 5793 5794 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 5795 size_t pre_used = 0; 5796 FreeRegionList local_free_list("Local List for CSet Freeing"); 5797 5798 double young_time_ms = 0.0; 5799 double non_young_time_ms = 0.0; 5800 5801 // Since the collection set is a superset of the the young list, 5802 // all we need to do to clear the young list is clear its 5803 // head and length, and unlink any young regions in the code below 5804 _young_list->clear(); 5805 5806 G1CollectorPolicy* policy = g1_policy(); 5807 5808 double start_sec = os::elapsedTime(); 5809 bool non_young = true; 5810 5811 HeapRegion* cur = cs_head; 5812 int age_bound = -1; 5813 size_t rs_lengths = 0; 5814 5815 while (cur != NULL) { 5816 assert(!is_on_master_free_list(cur), "sanity"); 5817 if (non_young) { 5818 if (cur->is_young()) { 5819 double end_sec = os::elapsedTime(); 5820 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5821 non_young_time_ms += elapsed_ms; 5822 5823 start_sec = os::elapsedTime(); 5824 non_young = false; 5825 } 5826 } else { 5827 if (!cur->is_young()) { 5828 double end_sec = os::elapsedTime(); 5829 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5830 young_time_ms += elapsed_ms; 5831 5832 start_sec = os::elapsedTime(); 5833 non_young = true; 5834 } 5835 } 5836 5837 rs_lengths += cur->rem_set()->occupied_locked(); 5838 5839 HeapRegion* next = cur->next_in_collection_set(); 5840 assert(cur->in_collection_set(), "bad CS"); 5841 cur->set_next_in_collection_set(NULL); 5842 clear_in_cset(cur); 5843 5844 if (cur->is_young()) { 5845 int index = cur->young_index_in_cset(); 5846 assert(index != -1, "invariant"); 5847 assert((uint) index < policy->young_cset_region_length(), "invariant"); 5848 size_t words_survived = _surviving_young_words[index]; 5849 cur->record_surv_words_in_group(words_survived); 5850 5851 // At this point the we have 'popped' cur from the collection set 5852 // (linked via next_in_collection_set()) but it is still in the 5853 // young list (linked via next_young_region()). Clear the 5854 // _next_young_region field. 5855 cur->set_next_young_region(NULL); 5856 } else { 5857 int index = cur->young_index_in_cset(); 5858 assert(index == -1, "invariant"); 5859 } 5860 5861 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 5862 (!cur->is_young() && cur->young_index_in_cset() == -1), 5863 "invariant" ); 5864 5865 if (!cur->evacuation_failed()) { 5866 MemRegion used_mr = cur->used_region(); 5867 5868 // And the region is empty. 5869 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 5870 pre_used += cur->used(); 5871 free_region(cur, &local_free_list, false /* par */, true /* locked */); 5872 } else { 5873 cur->uninstall_surv_rate_group(); 5874 if (cur->is_young()) { 5875 cur->set_young_index_in_cset(-1); 5876 } 5877 cur->set_evacuation_failed(false); 5878 // The region is now considered to be old. 5879 cur->set_old(); 5880 _old_set.add(cur); 5881 evacuation_info.increment_collectionset_used_after(cur->used()); 5882 } 5883 cur = next; 5884 } 5885 5886 evacuation_info.set_regions_freed(local_free_list.length()); 5887 policy->record_max_rs_lengths(rs_lengths); 5888 policy->cset_regions_freed(); 5889 5890 double end_sec = os::elapsedTime(); 5891 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5892 5893 if (non_young) { 5894 non_young_time_ms += elapsed_ms; 5895 } else { 5896 young_time_ms += elapsed_ms; 5897 } 5898 5899 prepend_to_freelist(&local_free_list); 5900 decrement_summary_bytes(pre_used); 5901 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 5902 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 5903 } 5904 5905 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 5906 private: 5907 FreeRegionList* _free_region_list; 5908 HeapRegionSet* _proxy_set; 5909 HeapRegionSetCount _humongous_regions_removed; 5910 size_t _freed_bytes; 5911 public: 5912 5913 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 5914 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 5915 } 5916 5917 virtual bool doHeapRegion(HeapRegion* r) { 5918 if (!r->is_starts_humongous()) { 5919 return false; 5920 } 5921 5922 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 5923 5924 oop obj = (oop)r->bottom(); 5925 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 5926 5927 // The following checks whether the humongous object is live are sufficient. 5928 // The main additional check (in addition to having a reference from the roots 5929 // or the young gen) is whether the humongous object has a remembered set entry. 5930 // 5931 // A humongous object cannot be live if there is no remembered set for it 5932 // because: 5933 // - there can be no references from within humongous starts regions referencing 5934 // the object because we never allocate other objects into them. 5935 // (I.e. there are no intra-region references that may be missed by the 5936 // remembered set) 5937 // - as soon there is a remembered set entry to the humongous starts region 5938 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 5939 // until the end of a concurrent mark. 5940 // 5941 // It is not required to check whether the object has been found dead by marking 5942 // or not, in fact it would prevent reclamation within a concurrent cycle, as 5943 // all objects allocated during that time are considered live. 5944 // SATB marking is even more conservative than the remembered set. 5945 // So if at this point in the collection there is no remembered set entry, 5946 // nobody has a reference to it. 5947 // At the start of collection we flush all refinement logs, and remembered sets 5948 // are completely up-to-date wrt to references to the humongous object. 5949 // 5950 // Other implementation considerations: 5951 // - never consider object arrays at this time because they would pose 5952 // considerable effort for cleaning up the the remembered sets. This is 5953 // required because stale remembered sets might reference locations that 5954 // are currently allocated into. 5955 uint region_idx = r->hrm_index(); 5956 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 5957 !r->rem_set()->is_empty()) { 5958 5959 if (G1TraceEagerReclaimHumongousObjects) { 5960 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", 5961 region_idx, 5962 (size_t)obj->size() * HeapWordSize, 5963 p2i(r->bottom()), 5964 r->region_num(), 5965 r->rem_set()->occupied(), 5966 r->rem_set()->strong_code_roots_list_length(), 5967 next_bitmap->isMarked(r->bottom()), 5968 g1h->is_humongous_reclaim_candidate(region_idx), 5969 obj->is_typeArray() 5970 ); 5971 } 5972 5973 return false; 5974 } 5975 5976 guarantee(obj->is_typeArray(), 5977 err_msg("Only eagerly reclaiming type arrays is supported, but the object " 5978 PTR_FORMAT " is not.", 5979 p2i(r->bottom()))); 5980 5981 if (G1TraceEagerReclaimHumongousObjects) { 5982 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", 5983 region_idx, 5984 (size_t)obj->size() * HeapWordSize, 5985 p2i(r->bottom()), 5986 r->region_num(), 5987 r->rem_set()->occupied(), 5988 r->rem_set()->strong_code_roots_list_length(), 5989 next_bitmap->isMarked(r->bottom()), 5990 g1h->is_humongous_reclaim_candidate(region_idx), 5991 obj->is_typeArray() 5992 ); 5993 } 5994 // Need to clear mark bit of the humongous object if already set. 5995 if (next_bitmap->isMarked(r->bottom())) { 5996 next_bitmap->clear(r->bottom()); 5997 } 5998 _freed_bytes += r->used(); 5999 r->set_containing_set(NULL); 6000 _humongous_regions_removed.increment(1u, r->capacity()); 6001 g1h->free_humongous_region(r, _free_region_list, false); 6002 6003 return false; 6004 } 6005 6006 HeapRegionSetCount& humongous_free_count() { 6007 return _humongous_regions_removed; 6008 } 6009 6010 size_t bytes_freed() const { 6011 return _freed_bytes; 6012 } 6013 6014 size_t humongous_reclaimed() const { 6015 return _humongous_regions_removed.length(); 6016 } 6017 }; 6018 6019 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 6020 assert_at_safepoint(true); 6021 6022 if (!G1EagerReclaimHumongousObjects || 6023 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) { 6024 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 6025 return; 6026 } 6027 6028 double start_time = os::elapsedTime(); 6029 6030 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 6031 6032 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 6033 heap_region_iterate(&cl); 6034 6035 HeapRegionSetCount empty_set; 6036 remove_from_old_sets(empty_set, cl.humongous_free_count()); 6037 6038 G1HRPrinter* hrp = hr_printer(); 6039 if (hrp->is_active()) { 6040 FreeRegionListIterator iter(&local_cleanup_list); 6041 while (iter.more_available()) { 6042 HeapRegion* hr = iter.get_next(); 6043 hrp->cleanup(hr); 6044 } 6045 } 6046 6047 prepend_to_freelist(&local_cleanup_list); 6048 decrement_summary_bytes(cl.bytes_freed()); 6049 6050 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 6051 cl.humongous_reclaimed()); 6052 } 6053 6054 // This routine is similar to the above but does not record 6055 // any policy statistics or update free lists; we are abandoning 6056 // the current incremental collection set in preparation of a 6057 // full collection. After the full GC we will start to build up 6058 // the incremental collection set again. 6059 // This is only called when we're doing a full collection 6060 // and is immediately followed by the tearing down of the young list. 6061 6062 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6063 HeapRegion* cur = cs_head; 6064 6065 while (cur != NULL) { 6066 HeapRegion* next = cur->next_in_collection_set(); 6067 assert(cur->in_collection_set(), "bad CS"); 6068 cur->set_next_in_collection_set(NULL); 6069 clear_in_cset(cur); 6070 cur->set_young_index_in_cset(-1); 6071 cur = next; 6072 } 6073 } 6074 6075 void G1CollectedHeap::set_free_regions_coming() { 6076 if (G1ConcRegionFreeingVerbose) { 6077 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6078 "setting free regions coming"); 6079 } 6080 6081 assert(!free_regions_coming(), "pre-condition"); 6082 _free_regions_coming = true; 6083 } 6084 6085 void G1CollectedHeap::reset_free_regions_coming() { 6086 assert(free_regions_coming(), "pre-condition"); 6087 6088 { 6089 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6090 _free_regions_coming = false; 6091 SecondaryFreeList_lock->notify_all(); 6092 } 6093 6094 if (G1ConcRegionFreeingVerbose) { 6095 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6096 "reset free regions coming"); 6097 } 6098 } 6099 6100 void G1CollectedHeap::wait_while_free_regions_coming() { 6101 // Most of the time we won't have to wait, so let's do a quick test 6102 // first before we take the lock. 6103 if (!free_regions_coming()) { 6104 return; 6105 } 6106 6107 if (G1ConcRegionFreeingVerbose) { 6108 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6109 "waiting for free regions"); 6110 } 6111 6112 { 6113 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6114 while (free_regions_coming()) { 6115 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6116 } 6117 } 6118 6119 if (G1ConcRegionFreeingVerbose) { 6120 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6121 "done waiting for free regions"); 6122 } 6123 } 6124 6125 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6126 _young_list->push_region(hr); 6127 } 6128 6129 class NoYoungRegionsClosure: public HeapRegionClosure { 6130 private: 6131 bool _success; 6132 public: 6133 NoYoungRegionsClosure() : _success(true) { } 6134 bool doHeapRegion(HeapRegion* r) { 6135 if (r->is_young()) { 6136 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6137 p2i(r->bottom()), p2i(r->end())); 6138 _success = false; 6139 } 6140 return false; 6141 } 6142 bool success() { return _success; } 6143 }; 6144 6145 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6146 bool ret = _young_list->check_list_empty(check_sample); 6147 6148 if (check_heap) { 6149 NoYoungRegionsClosure closure; 6150 heap_region_iterate(&closure); 6151 ret = ret && closure.success(); 6152 } 6153 6154 return ret; 6155 } 6156 6157 class TearDownRegionSetsClosure : public HeapRegionClosure { 6158 private: 6159 HeapRegionSet *_old_set; 6160 6161 public: 6162 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6163 6164 bool doHeapRegion(HeapRegion* r) { 6165 if (r->is_old()) { 6166 _old_set->remove(r); 6167 } else { 6168 // We ignore free regions, we'll empty the free list afterwards. 6169 // We ignore young regions, we'll empty the young list afterwards. 6170 // We ignore humongous regions, we're not tearing down the 6171 // humongous regions set. 6172 assert(r->is_free() || r->is_young() || r->is_humongous(), 6173 "it cannot be another type"); 6174 } 6175 return false; 6176 } 6177 6178 ~TearDownRegionSetsClosure() { 6179 assert(_old_set->is_empty(), "post-condition"); 6180 } 6181 }; 6182 6183 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6184 assert_at_safepoint(true /* should_be_vm_thread */); 6185 6186 if (!free_list_only) { 6187 TearDownRegionSetsClosure cl(&_old_set); 6188 heap_region_iterate(&cl); 6189 6190 // Note that emptying the _young_list is postponed and instead done as 6191 // the first step when rebuilding the regions sets again. The reason for 6192 // this is that during a full GC string deduplication needs to know if 6193 // a collected region was young or old when the full GC was initiated. 6194 } 6195 _hrm.remove_all_free_regions(); 6196 } 6197 6198 class RebuildRegionSetsClosure : public HeapRegionClosure { 6199 private: 6200 bool _free_list_only; 6201 HeapRegionSet* _old_set; 6202 HeapRegionManager* _hrm; 6203 size_t _total_used; 6204 6205 public: 6206 RebuildRegionSetsClosure(bool free_list_only, 6207 HeapRegionSet* old_set, HeapRegionManager* hrm) : 6208 _free_list_only(free_list_only), 6209 _old_set(old_set), _hrm(hrm), _total_used(0) { 6210 assert(_hrm->num_free_regions() == 0, "pre-condition"); 6211 if (!free_list_only) { 6212 assert(_old_set->is_empty(), "pre-condition"); 6213 } 6214 } 6215 6216 bool doHeapRegion(HeapRegion* r) { 6217 if (r->is_continues_humongous()) { 6218 return false; 6219 } 6220 6221 if (r->is_empty()) { 6222 // Add free regions to the free list 6223 r->set_free(); 6224 r->set_allocation_context(AllocationContext::system()); 6225 _hrm->insert_into_free_list(r); 6226 } else if (!_free_list_only) { 6227 assert(!r->is_young(), "we should not come across young regions"); 6228 6229 if (r->is_humongous()) { 6230 // We ignore humongous regions, we left the humongous set unchanged 6231 } else { 6232 // Objects that were compacted would have ended up on regions 6233 // that were previously old or free. 6234 assert(r->is_free() || r->is_old(), "invariant"); 6235 // We now consider them old, so register as such. 6236 r->set_old(); 6237 _old_set->add(r); 6238 } 6239 _total_used += r->used(); 6240 } 6241 6242 return false; 6243 } 6244 6245 size_t total_used() { 6246 return _total_used; 6247 } 6248 }; 6249 6250 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6251 assert_at_safepoint(true /* should_be_vm_thread */); 6252 6253 if (!free_list_only) { 6254 _young_list->empty_list(); 6255 } 6256 6257 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 6258 heap_region_iterate(&cl); 6259 6260 if (!free_list_only) { 6261 _allocator->set_used(cl.total_used()); 6262 } 6263 assert(_allocator->used_unlocked() == recalculate_used(), 6264 err_msg("inconsistent _allocator->used_unlocked(), " 6265 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6266 _allocator->used_unlocked(), recalculate_used())); 6267 } 6268 6269 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6270 _refine_cte_cl->set_concurrent(concurrent); 6271 } 6272 6273 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6274 HeapRegion* hr = heap_region_containing(p); 6275 return hr->is_in(p); 6276 } 6277 6278 // Methods for the mutator alloc region 6279 6280 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6281 bool force) { 6282 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6283 assert(!force || g1_policy()->can_expand_young_list(), 6284 "if force is true we should be able to expand the young list"); 6285 bool young_list_full = g1_policy()->is_young_list_full(); 6286 if (force || !young_list_full) { 6287 HeapRegion* new_alloc_region = new_region(word_size, 6288 false /* is_old */, 6289 false /* do_expand */); 6290 if (new_alloc_region != NULL) { 6291 set_region_short_lived_locked(new_alloc_region); 6292 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6293 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6294 return new_alloc_region; 6295 } 6296 } 6297 return NULL; 6298 } 6299 6300 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6301 size_t allocated_bytes) { 6302 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6303 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 6304 6305 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6306 _allocator->increase_used(allocated_bytes); 6307 _hr_printer.retire(alloc_region); 6308 // We update the eden sizes here, when the region is retired, 6309 // instead of when it's allocated, since this is the point that its 6310 // used space has been recored in _summary_bytes_used. 6311 g1mm()->update_eden_size(); 6312 } 6313 6314 void G1CollectedHeap::set_par_threads() { 6315 // Don't change the number of workers. Use the value previously set 6316 // in the workgroup. 6317 uint n_workers = workers()->active_workers(); 6318 assert(UseDynamicNumberOfGCThreads || 6319 n_workers == workers()->total_workers(), 6320 "Otherwise should be using the total number of workers"); 6321 if (n_workers == 0) { 6322 assert(false, "Should have been set in prior evacuation pause."); 6323 n_workers = ParallelGCThreads; 6324 workers()->set_active_workers(n_workers); 6325 } 6326 set_par_threads(n_workers); 6327 } 6328 6329 // Methods for the GC alloc regions 6330 6331 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6332 uint count, 6333 InCSetState dest) { 6334 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6335 6336 if (count < g1_policy()->max_regions(dest)) { 6337 const bool is_survivor = (dest.is_young()); 6338 HeapRegion* new_alloc_region = new_region(word_size, 6339 !is_survivor, 6340 true /* do_expand */); 6341 if (new_alloc_region != NULL) { 6342 // We really only need to do this for old regions given that we 6343 // should never scan survivors. But it doesn't hurt to do it 6344 // for survivors too. 6345 new_alloc_region->record_timestamp(); 6346 if (is_survivor) { 6347 new_alloc_region->set_survivor(); 6348 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6349 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6350 } else { 6351 new_alloc_region->set_old(); 6352 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6353 check_bitmaps("Old Region Allocation", new_alloc_region); 6354 } 6355 bool during_im = collector_state()->during_initial_mark_pause(); 6356 new_alloc_region->note_start_of_copying(during_im); 6357 return new_alloc_region; 6358 } 6359 } 6360 return NULL; 6361 } 6362 6363 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6364 size_t allocated_bytes, 6365 InCSetState dest) { 6366 bool during_im = collector_state()->during_initial_mark_pause(); 6367 alloc_region->note_end_of_copying(during_im); 6368 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6369 if (dest.is_young()) { 6370 young_list()->add_survivor_region(alloc_region); 6371 } else { 6372 _old_set.add(alloc_region); 6373 } 6374 _hr_printer.retire(alloc_region); 6375 } 6376 6377 // Heap region set verification 6378 6379 class VerifyRegionListsClosure : public HeapRegionClosure { 6380 private: 6381 HeapRegionSet* _old_set; 6382 HeapRegionSet* _humongous_set; 6383 HeapRegionManager* _hrm; 6384 6385 public: 6386 HeapRegionSetCount _old_count; 6387 HeapRegionSetCount _humongous_count; 6388 HeapRegionSetCount _free_count; 6389 6390 VerifyRegionListsClosure(HeapRegionSet* old_set, 6391 HeapRegionSet* humongous_set, 6392 HeapRegionManager* hrm) : 6393 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm), 6394 _old_count(), _humongous_count(), _free_count(){ } 6395 6396 bool doHeapRegion(HeapRegion* hr) { 6397 if (hr->is_continues_humongous()) { 6398 return false; 6399 } 6400 6401 if (hr->is_young()) { 6402 // TODO 6403 } else if (hr->is_starts_humongous()) { 6404 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index())); 6405 _humongous_count.increment(1u, hr->capacity()); 6406 } else if (hr->is_empty()) { 6407 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index())); 6408 _free_count.increment(1u, hr->capacity()); 6409 } else if (hr->is_old()) { 6410 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index())); 6411 _old_count.increment(1u, hr->capacity()); 6412 } else { 6413 ShouldNotReachHere(); 6414 } 6415 return false; 6416 } 6417 6418 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) { 6419 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 6420 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6421 old_set->total_capacity_bytes(), _old_count.capacity())); 6422 6423 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 6424 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6425 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 6426 6427 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())); 6428 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6429 free_list->total_capacity_bytes(), _free_count.capacity())); 6430 } 6431 }; 6432 6433 void G1CollectedHeap::verify_region_sets() { 6434 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6435 6436 // First, check the explicit lists. 6437 _hrm.verify(); 6438 { 6439 // Given that a concurrent operation might be adding regions to 6440 // the secondary free list we have to take the lock before 6441 // verifying it. 6442 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6443 _secondary_free_list.verify_list(); 6444 } 6445 6446 // If a concurrent region freeing operation is in progress it will 6447 // be difficult to correctly attributed any free regions we come 6448 // across to the correct free list given that they might belong to 6449 // one of several (free_list, secondary_free_list, any local lists, 6450 // etc.). So, if that's the case we will skip the rest of the 6451 // verification operation. Alternatively, waiting for the concurrent 6452 // operation to complete will have a non-trivial effect on the GC's 6453 // operation (no concurrent operation will last longer than the 6454 // interval between two calls to verification) and it might hide 6455 // any issues that we would like to catch during testing. 6456 if (free_regions_coming()) { 6457 return; 6458 } 6459 6460 // Make sure we append the secondary_free_list on the free_list so 6461 // that all free regions we will come across can be safely 6462 // attributed to the free_list. 6463 append_secondary_free_list_if_not_empty_with_lock(); 6464 6465 // Finally, make sure that the region accounting in the lists is 6466 // consistent with what we see in the heap. 6467 6468 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm); 6469 heap_region_iterate(&cl); 6470 cl.verify_counts(&_old_set, &_humongous_set, &_hrm); 6471 } 6472 6473 // Optimized nmethod scanning 6474 6475 class RegisterNMethodOopClosure: public OopClosure { 6476 G1CollectedHeap* _g1h; 6477 nmethod* _nm; 6478 6479 template <class T> void do_oop_work(T* p) { 6480 T heap_oop = oopDesc::load_heap_oop(p); 6481 if (!oopDesc::is_null(heap_oop)) { 6482 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6483 HeapRegion* hr = _g1h->heap_region_containing(obj); 6484 assert(!hr->is_continues_humongous(), 6485 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6486 " starting at "HR_FORMAT, 6487 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6488 6489 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 6490 hr->add_strong_code_root_locked(_nm); 6491 } 6492 } 6493 6494 public: 6495 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6496 _g1h(g1h), _nm(nm) {} 6497 6498 void do_oop(oop* p) { do_oop_work(p); } 6499 void do_oop(narrowOop* p) { do_oop_work(p); } 6500 }; 6501 6502 class UnregisterNMethodOopClosure: public OopClosure { 6503 G1CollectedHeap* _g1h; 6504 nmethod* _nm; 6505 6506 template <class T> void do_oop_work(T* p) { 6507 T heap_oop = oopDesc::load_heap_oop(p); 6508 if (!oopDesc::is_null(heap_oop)) { 6509 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6510 HeapRegion* hr = _g1h->heap_region_containing(obj); 6511 assert(!hr->is_continues_humongous(), 6512 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6513 " starting at "HR_FORMAT, 6514 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6515 6516 hr->remove_strong_code_root(_nm); 6517 } 6518 } 6519 6520 public: 6521 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6522 _g1h(g1h), _nm(nm) {} 6523 6524 void do_oop(oop* p) { do_oop_work(p); } 6525 void do_oop(narrowOop* p) { do_oop_work(p); } 6526 }; 6527 6528 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6529 CollectedHeap::register_nmethod(nm); 6530 6531 guarantee(nm != NULL, "sanity"); 6532 RegisterNMethodOopClosure reg_cl(this, nm); 6533 nm->oops_do(®_cl); 6534 } 6535 6536 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6537 CollectedHeap::unregister_nmethod(nm); 6538 6539 guarantee(nm != NULL, "sanity"); 6540 UnregisterNMethodOopClosure reg_cl(this, nm); 6541 nm->oops_do(®_cl, true); 6542 } 6543 6544 void G1CollectedHeap::purge_code_root_memory() { 6545 double purge_start = os::elapsedTime(); 6546 G1CodeRootSet::purge(); 6547 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6548 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6549 } 6550 6551 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6552 G1CollectedHeap* _g1h; 6553 6554 public: 6555 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6556 _g1h(g1h) {} 6557 6558 void do_code_blob(CodeBlob* cb) { 6559 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6560 if (nm == NULL) { 6561 return; 6562 } 6563 6564 if (ScavengeRootsInCode) { 6565 _g1h->register_nmethod(nm); 6566 } 6567 } 6568 }; 6569 6570 void G1CollectedHeap::rebuild_strong_code_roots() { 6571 RebuildStrongCodeRootClosure blob_cl(this); 6572 CodeCache::blobs_do(&blob_cl); 6573 }