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 #if !defined(__clang_major__) && defined(__GNUC__) 26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information. 27 #define ATTRIBUTE_PRINTF(x,y) 28 #endif 29 30 #include "precompiled.hpp" 31 #include "classfile/metadataOnStackMark.hpp" 32 #include "classfile/stringTable.hpp" 33 #include "code/codeCache.hpp" 34 #include "code/icBuffer.hpp" 35 #include "gc_implementation/g1/bufferingOopClosure.hpp" 36 #include "gc_implementation/g1/concurrentG1Refine.hpp" 37 #include "gc_implementation/g1/concurrentG1RefineThread.hpp" 38 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 39 #include "gc_implementation/g1/g1AllocRegion.inline.hpp" 40 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 41 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 42 #include "gc_implementation/g1/g1ErgoVerbose.hpp" 43 #include "gc_implementation/g1/g1EvacFailure.hpp" 44 #include "gc_implementation/g1/g1GCPhaseTimes.hpp" 45 #include "gc_implementation/g1/g1Log.hpp" 46 #include "gc_implementation/g1/g1MarkSweep.hpp" 47 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 48 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp" 49 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp" 50 #include "gc_implementation/g1/g1RemSet.inline.hpp" 51 #include "gc_implementation/g1/g1RootProcessor.hpp" 52 #include "gc_implementation/g1/g1StringDedup.hpp" 53 #include "gc_implementation/g1/g1YCTypes.hpp" 54 #include "gc_implementation/g1/heapRegion.inline.hpp" 55 #include "gc_implementation/g1/heapRegionRemSet.hpp" 56 #include "gc_implementation/g1/heapRegionSet.inline.hpp" 57 #include "gc_implementation/g1/vm_operations_g1.hpp" 58 #include "gc_implementation/shared/gcHeapSummary.hpp" 59 #include "gc_implementation/shared/gcTimer.hpp" 60 #include "gc_implementation/shared/gcTrace.hpp" 61 #include "gc_implementation/shared/gcTraceTime.hpp" 62 #include "gc_implementation/shared/isGCActiveMark.hpp" 63 #include "memory/allocation.hpp" 64 #include "memory/gcLocker.inline.hpp" 65 #include "memory/generationSpec.hpp" 66 #include "memory/iterator.hpp" 67 #include "memory/referenceProcessor.hpp" 68 #include "oops/oop.inline.hpp" 69 #include "runtime/atomic.inline.hpp" 70 #include "runtime/orderAccess.inline.hpp" 71 #include "runtime/vmThread.hpp" 72 #include "utilities/globalDefinitions.hpp" 73 74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 75 76 // turn it on so that the contents of the young list (scan-only / 77 // to-be-collected) are printed at "strategic" points before / during 78 // / after the collection --- this is useful for debugging 79 #define YOUNG_LIST_VERBOSE 0 80 // CURRENT STATUS 81 // This file is under construction. Search for "FIXME". 82 83 // INVARIANTS/NOTES 84 // 85 // All allocation activity covered by the G1CollectedHeap interface is 86 // serialized by acquiring the HeapLock. This happens in mem_allocate 87 // and allocate_new_tlab, which are the "entry" points to the 88 // allocation code from the rest of the JVM. (Note that this does not 89 // apply to TLAB allocation, which is not part of this interface: it 90 // is done by clients of this interface.) 91 92 // Local to this file. 93 94 class RefineCardTableEntryClosure: public CardTableEntryClosure { 95 bool _concurrent; 96 public: 97 RefineCardTableEntryClosure() : _concurrent(true) { } 98 99 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 100 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 101 // This path is executed by the concurrent refine or mutator threads, 102 // concurrently, and so we do not care if card_ptr contains references 103 // that point into the collection set. 104 assert(!oops_into_cset, "should be"); 105 106 if (_concurrent && SuspendibleThreadSet::should_yield()) { 107 // Caller will actually yield. 108 return false; 109 } 110 // Otherwise, we finished successfully; return true. 111 return true; 112 } 113 114 void set_concurrent(bool b) { _concurrent = b; } 115 }; 116 117 118 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 119 private: 120 size_t _num_processed; 121 122 public: 123 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { } 124 125 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 126 *card_ptr = CardTableModRefBS::dirty_card_val(); 127 _num_processed++; 128 return true; 129 } 130 131 size_t num_processed() const { return _num_processed; } 132 }; 133 134 YoungList::YoungList(G1CollectedHeap* g1h) : 135 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 136 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 137 guarantee(check_list_empty(false), "just making sure..."); 138 } 139 140 void YoungList::push_region(HeapRegion *hr) { 141 assert(!hr->is_young(), "should not already be young"); 142 assert(hr->get_next_young_region() == NULL, "cause it should!"); 143 144 hr->set_next_young_region(_head); 145 _head = hr; 146 147 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 148 ++_length; 149 } 150 151 void YoungList::add_survivor_region(HeapRegion* hr) { 152 assert(hr->is_survivor(), "should be flagged as survivor region"); 153 assert(hr->get_next_young_region() == NULL, "cause it should!"); 154 155 hr->set_next_young_region(_survivor_head); 156 if (_survivor_head == NULL) { 157 _survivor_tail = hr; 158 } 159 _survivor_head = hr; 160 ++_survivor_length; 161 } 162 163 void YoungList::empty_list(HeapRegion* list) { 164 while (list != NULL) { 165 HeapRegion* next = list->get_next_young_region(); 166 list->set_next_young_region(NULL); 167 list->uninstall_surv_rate_group(); 168 // This is called before a Full GC and all the non-empty / 169 // non-humongous regions at the end of the Full GC will end up as 170 // old anyway. 171 list->set_old(); 172 list = next; 173 } 174 } 175 176 void YoungList::empty_list() { 177 assert(check_list_well_formed(), "young list should be well formed"); 178 179 empty_list(_head); 180 _head = NULL; 181 _length = 0; 182 183 empty_list(_survivor_head); 184 _survivor_head = NULL; 185 _survivor_tail = NULL; 186 _survivor_length = 0; 187 188 _last_sampled_rs_lengths = 0; 189 190 assert(check_list_empty(false), "just making sure..."); 191 } 192 193 bool YoungList::check_list_well_formed() { 194 bool ret = true; 195 196 uint length = 0; 197 HeapRegion* curr = _head; 198 HeapRegion* last = NULL; 199 while (curr != NULL) { 200 if (!curr->is_young()) { 201 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " 202 "incorrectly tagged (y: %d, surv: %d)", 203 curr->bottom(), curr->end(), 204 curr->is_young(), curr->is_survivor()); 205 ret = false; 206 } 207 ++length; 208 last = curr; 209 curr = curr->get_next_young_region(); 210 } 211 ret = ret && (length == _length); 212 213 if (!ret) { 214 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 215 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 216 length, _length); 217 } 218 219 return ret; 220 } 221 222 bool YoungList::check_list_empty(bool check_sample) { 223 bool ret = true; 224 225 if (_length != 0) { 226 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 227 _length); 228 ret = false; 229 } 230 if (check_sample && _last_sampled_rs_lengths != 0) { 231 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 232 ret = false; 233 } 234 if (_head != NULL) { 235 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 236 ret = false; 237 } 238 if (!ret) { 239 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 240 } 241 242 return ret; 243 } 244 245 void 246 YoungList::rs_length_sampling_init() { 247 _sampled_rs_lengths = 0; 248 _curr = _head; 249 } 250 251 bool 252 YoungList::rs_length_sampling_more() { 253 return _curr != NULL; 254 } 255 256 void 257 YoungList::rs_length_sampling_next() { 258 assert( _curr != NULL, "invariant" ); 259 size_t rs_length = _curr->rem_set()->occupied(); 260 261 _sampled_rs_lengths += rs_length; 262 263 // The current region may not yet have been added to the 264 // incremental collection set (it gets added when it is 265 // retired as the current allocation region). 266 if (_curr->in_collection_set()) { 267 // Update the collection set policy information for this region 268 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 269 } 270 271 _curr = _curr->get_next_young_region(); 272 if (_curr == NULL) { 273 _last_sampled_rs_lengths = _sampled_rs_lengths; 274 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 275 } 276 } 277 278 void 279 YoungList::reset_auxilary_lists() { 280 guarantee( is_empty(), "young list should be empty" ); 281 assert(check_list_well_formed(), "young list should be well formed"); 282 283 // Add survivor regions to SurvRateGroup. 284 _g1h->g1_policy()->note_start_adding_survivor_regions(); 285 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 286 287 int young_index_in_cset = 0; 288 for (HeapRegion* curr = _survivor_head; 289 curr != NULL; 290 curr = curr->get_next_young_region()) { 291 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 292 293 // The region is a non-empty survivor so let's add it to 294 // the incremental collection set for the next evacuation 295 // pause. 296 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 297 young_index_in_cset += 1; 298 } 299 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 300 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 301 302 _head = _survivor_head; 303 _length = _survivor_length; 304 if (_survivor_head != NULL) { 305 assert(_survivor_tail != NULL, "cause it shouldn't be"); 306 assert(_survivor_length > 0, "invariant"); 307 _survivor_tail->set_next_young_region(NULL); 308 } 309 310 // Don't clear the survivor list handles until the start of 311 // the next evacuation pause - we need it in order to re-tag 312 // the survivor regions from this evacuation pause as 'young' 313 // at the start of the next. 314 315 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 316 317 assert(check_list_well_formed(), "young list should be well formed"); 318 } 319 320 void YoungList::print() { 321 HeapRegion* lists[] = {_head, _survivor_head}; 322 const char* names[] = {"YOUNG", "SURVIVOR"}; 323 324 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) { 325 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 326 HeapRegion *curr = lists[list]; 327 if (curr == NULL) 328 gclog_or_tty->print_cr(" empty"); 329 while (curr != NULL) { 330 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d", 331 HR_FORMAT_PARAMS(curr), 332 curr->prev_top_at_mark_start(), 333 curr->next_top_at_mark_start(), 334 curr->age_in_surv_rate_group_cond()); 335 curr = curr->get_next_young_region(); 336 } 337 } 338 339 gclog_or_tty->cr(); 340 } 341 342 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 343 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 344 } 345 346 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 347 // The from card cache is not the memory that is actually committed. So we cannot 348 // take advantage of the zero_filled parameter. 349 reset_from_card_cache(start_idx, num_regions); 350 } 351 352 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 353 { 354 // Claim the right to put the region on the dirty cards region list 355 // by installing a self pointer. 356 HeapRegion* next = hr->get_next_dirty_cards_region(); 357 if (next == NULL) { 358 HeapRegion* res = (HeapRegion*) 359 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 360 NULL); 361 if (res == NULL) { 362 HeapRegion* head; 363 do { 364 // Put the region to the dirty cards region list. 365 head = _dirty_cards_region_list; 366 next = (HeapRegion*) 367 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 368 if (next == head) { 369 assert(hr->get_next_dirty_cards_region() == hr, 370 "hr->get_next_dirty_cards_region() != hr"); 371 if (next == NULL) { 372 // The last region in the list points to itself. 373 hr->set_next_dirty_cards_region(hr); 374 } else { 375 hr->set_next_dirty_cards_region(next); 376 } 377 } 378 } while (next != head); 379 } 380 } 381 } 382 383 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 384 { 385 HeapRegion* head; 386 HeapRegion* hr; 387 do { 388 head = _dirty_cards_region_list; 389 if (head == NULL) { 390 return NULL; 391 } 392 HeapRegion* new_head = head->get_next_dirty_cards_region(); 393 if (head == new_head) { 394 // The last region. 395 new_head = NULL; 396 } 397 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 398 head); 399 } while (hr != head); 400 assert(hr != NULL, "invariant"); 401 hr->set_next_dirty_cards_region(NULL); 402 return hr; 403 } 404 405 // Returns true if the reference points to an object that 406 // can move in an incremental collection. 407 bool G1CollectedHeap::is_scavengable(const void* p) { 408 HeapRegion* hr = heap_region_containing(p); 409 return !hr->is_humongous(); 410 } 411 412 // Private class members. 413 414 G1CollectedHeap* G1CollectedHeap::_g1h; 415 416 // Private methods. 417 418 HeapRegion* 419 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 420 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 421 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 422 if (!_secondary_free_list.is_empty()) { 423 if (G1ConcRegionFreeingVerbose) { 424 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 425 "secondary_free_list has %u entries", 426 _secondary_free_list.length()); 427 } 428 // It looks as if there are free regions available on the 429 // secondary_free_list. Let's move them to the free_list and try 430 // again to allocate from it. 431 append_secondary_free_list(); 432 433 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 434 "empty we should have moved at least one entry to the free_list"); 435 HeapRegion* res = _hrm.allocate_free_region(is_old); 436 if (G1ConcRegionFreeingVerbose) { 437 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 438 "allocated "HR_FORMAT" from secondary_free_list", 439 HR_FORMAT_PARAMS(res)); 440 } 441 return res; 442 } 443 444 // Wait here until we get notified either when (a) there are no 445 // more free regions coming or (b) some regions have been moved on 446 // the secondary_free_list. 447 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 448 } 449 450 if (G1ConcRegionFreeingVerbose) { 451 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 452 "could not allocate from secondary_free_list"); 453 } 454 return NULL; 455 } 456 457 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 458 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 459 "the only time we use this to allocate a humongous region is " 460 "when we are allocating a single humongous region"); 461 462 HeapRegion* res; 463 if (G1StressConcRegionFreeing) { 464 if (!_secondary_free_list.is_empty()) { 465 if (G1ConcRegionFreeingVerbose) { 466 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 467 "forced to look at the secondary_free_list"); 468 } 469 res = new_region_try_secondary_free_list(is_old); 470 if (res != NULL) { 471 return res; 472 } 473 } 474 } 475 476 res = _hrm.allocate_free_region(is_old); 477 478 if (res == NULL) { 479 if (G1ConcRegionFreeingVerbose) { 480 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 481 "res == NULL, trying the secondary_free_list"); 482 } 483 res = new_region_try_secondary_free_list(is_old); 484 } 485 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 486 // Currently, only attempts to allocate GC alloc regions set 487 // do_expand to true. So, we should only reach here during a 488 // safepoint. If this assumption changes we might have to 489 // reconsider the use of _expand_heap_after_alloc_failure. 490 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 491 492 ergo_verbose1(ErgoHeapSizing, 493 "attempt heap expansion", 494 ergo_format_reason("region allocation request failed") 495 ergo_format_byte("allocation request"), 496 word_size * HeapWordSize); 497 if (expand(word_size * HeapWordSize)) { 498 // Given that expand() succeeded in expanding the heap, and we 499 // always expand the heap by an amount aligned to the heap 500 // region size, the free list should in theory not be empty. 501 // In either case allocate_free_region() will check for NULL. 502 res = _hrm.allocate_free_region(is_old); 503 } else { 504 _expand_heap_after_alloc_failure = false; 505 } 506 } 507 return res; 508 } 509 510 HeapWord* 511 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 512 uint num_regions, 513 size_t word_size, 514 AllocationContext_t context) { 515 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 516 assert(is_humongous(word_size), "word_size should be humongous"); 517 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 518 519 // Index of last region in the series + 1. 520 uint last = first + num_regions; 521 522 // We need to initialize the region(s) we just discovered. This is 523 // a bit tricky given that it can happen concurrently with 524 // refinement threads refining cards on these regions and 525 // potentially wanting to refine the BOT as they are scanning 526 // those cards (this can happen shortly after a cleanup; see CR 527 // 6991377). So we have to set up the region(s) carefully and in 528 // a specific order. 529 530 // The word size sum of all the regions we will allocate. 531 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 532 assert(word_size <= word_size_sum, "sanity"); 533 534 // This will be the "starts humongous" region. 535 HeapRegion* first_hr = region_at(first); 536 // The header of the new object will be placed at the bottom of 537 // the first region. 538 HeapWord* new_obj = first_hr->bottom(); 539 // This will be the new end of the first region in the series that 540 // should also match the end of the last region in the series. 541 HeapWord* new_end = new_obj + word_size_sum; 542 // This will be the new top of the first region that will reflect 543 // this allocation. 544 HeapWord* new_top = new_obj + word_size; 545 546 // First, we need to zero the header of the space that we will be 547 // allocating. When we update top further down, some refinement 548 // threads might try to scan the region. By zeroing the header we 549 // ensure that any thread that will try to scan the region will 550 // come across the zero klass word and bail out. 551 // 552 // NOTE: It would not have been correct to have used 553 // CollectedHeap::fill_with_object() and make the space look like 554 // an int array. The thread that is doing the allocation will 555 // later update the object header to a potentially different array 556 // type and, for a very short period of time, the klass and length 557 // fields will be inconsistent. This could cause a refinement 558 // thread to calculate the object size incorrectly. 559 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 560 561 // We will set up the first region as "starts humongous". This 562 // will also update the BOT covering all the regions to reflect 563 // that there is a single object that starts at the bottom of the 564 // first region. 565 first_hr->set_starts_humongous(new_top, new_end); 566 first_hr->set_allocation_context(context); 567 // Then, if there are any, we will set up the "continues 568 // humongous" regions. 569 HeapRegion* hr = NULL; 570 for (uint i = first + 1; i < last; ++i) { 571 hr = region_at(i); 572 hr->set_continues_humongous(first_hr); 573 hr->set_allocation_context(context); 574 } 575 // If we have "continues humongous" regions (hr != NULL), then the 576 // end of the last one should match new_end. 577 assert(hr == NULL || hr->end() == new_end, "sanity"); 578 579 // Up to this point no concurrent thread would have been able to 580 // do any scanning on any region in this series. All the top 581 // fields still point to bottom, so the intersection between 582 // [bottom,top] and [card_start,card_end] will be empty. Before we 583 // update the top fields, we'll do a storestore to make sure that 584 // no thread sees the update to top before the zeroing of the 585 // object header and the BOT initialization. 586 OrderAccess::storestore(); 587 588 // Now that the BOT and the object header have been initialized, 589 // we can update top of the "starts humongous" region. 590 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 591 "new_top should be in this region"); 592 first_hr->set_top(new_top); 593 if (_hr_printer.is_active()) { 594 HeapWord* bottom = first_hr->bottom(); 595 HeapWord* end = first_hr->orig_end(); 596 if ((first + 1) == last) { 597 // the series has a single humongous region 598 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 599 } else { 600 // the series has more than one humongous regions 601 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 602 } 603 } 604 605 // Now, we will update the top fields of the "continues humongous" 606 // regions. The reason we need to do this is that, otherwise, 607 // these regions would look empty and this will confuse parts of 608 // G1. For example, the code that looks for a consecutive number 609 // of empty regions will consider them empty and try to 610 // re-allocate them. We can extend is_empty() to also include 611 // !is_continues_humongous(), but it is easier to just update the top 612 // fields here. The way we set top for all regions (i.e., top == 613 // end for all regions but the last one, top == new_top for the 614 // last one) is actually used when we will free up the humongous 615 // region in free_humongous_region(). 616 hr = NULL; 617 for (uint i = first + 1; i < last; ++i) { 618 hr = region_at(i); 619 if ((i + 1) == last) { 620 // last continues humongous region 621 assert(hr->bottom() < new_top && new_top <= hr->end(), 622 "new_top should fall on this region"); 623 hr->set_top(new_top); 624 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 625 } else { 626 // not last one 627 assert(new_top > hr->end(), "new_top should be above this region"); 628 hr->set_top(hr->end()); 629 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 630 } 631 } 632 // If we have continues humongous regions (hr != NULL), then the 633 // end of the last one should match new_end and its top should 634 // match new_top. 635 assert(hr == NULL || 636 (hr->end() == new_end && hr->top() == new_top), "sanity"); 637 check_bitmaps("Humongous Region Allocation", first_hr); 638 639 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 640 _allocator->increase_used(first_hr->used()); 641 _humongous_set.add(first_hr); 642 643 return new_obj; 644 } 645 646 // If could fit into free regions w/o expansion, try. 647 // Otherwise, if can expand, do so. 648 // Otherwise, if using ex regions might help, try with ex given back. 649 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 650 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 651 652 verify_region_sets_optional(); 653 654 uint first = G1_NO_HRM_INDEX; 655 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords); 656 657 if (obj_regions == 1) { 658 // Only one region to allocate, try to use a fast path by directly allocating 659 // from the free lists. Do not try to expand here, we will potentially do that 660 // later. 661 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 662 if (hr != NULL) { 663 first = hr->hrm_index(); 664 } 665 } else { 666 // We can't allocate humongous regions spanning more than one region while 667 // cleanupComplete() is running, since some of the regions we find to be 668 // empty might not yet be added to the free list. It is not straightforward 669 // to know in which list they are on so that we can remove them. We only 670 // need to do this if we need to allocate more than one region to satisfy the 671 // current humongous allocation request. If we are only allocating one region 672 // we use the one-region region allocation code (see above), that already 673 // potentially waits for regions from the secondary free list. 674 wait_while_free_regions_coming(); 675 append_secondary_free_list_if_not_empty_with_lock(); 676 677 // Policy: Try only empty regions (i.e. already committed first). Maybe we 678 // are lucky enough to find some. 679 first = _hrm.find_contiguous_only_empty(obj_regions); 680 if (first != G1_NO_HRM_INDEX) { 681 _hrm.allocate_free_regions_starting_at(first, obj_regions); 682 } 683 } 684 685 if (first == G1_NO_HRM_INDEX) { 686 // Policy: We could not find enough regions for the humongous object in the 687 // free list. Look through the heap to find a mix of free and uncommitted regions. 688 // If so, try expansion. 689 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 690 if (first != G1_NO_HRM_INDEX) { 691 // We found something. Make sure these regions are committed, i.e. expand 692 // the heap. Alternatively we could do a defragmentation GC. 693 ergo_verbose1(ErgoHeapSizing, 694 "attempt heap expansion", 695 ergo_format_reason("humongous allocation request failed") 696 ergo_format_byte("allocation request"), 697 word_size * HeapWordSize); 698 699 _hrm.expand_at(first, obj_regions); 700 g1_policy()->record_new_heap_size(num_regions()); 701 702 #ifdef ASSERT 703 for (uint i = first; i < first + obj_regions; ++i) { 704 HeapRegion* hr = region_at(i); 705 assert(hr->is_free(), "sanity"); 706 assert(hr->is_empty(), "sanity"); 707 assert(is_on_master_free_list(hr), "sanity"); 708 } 709 #endif 710 _hrm.allocate_free_regions_starting_at(first, obj_regions); 711 } else { 712 // Policy: Potentially trigger a defragmentation GC. 713 } 714 } 715 716 HeapWord* result = NULL; 717 if (first != G1_NO_HRM_INDEX) { 718 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 719 word_size, context); 720 assert(result != NULL, "it should always return a valid result"); 721 722 // A successful humongous object allocation changes the used space 723 // information of the old generation so we need to recalculate the 724 // sizes and update the jstat counters here. 725 g1mm()->update_sizes(); 726 } 727 728 verify_region_sets_optional(); 729 730 return result; 731 } 732 733 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 734 assert_heap_not_locked_and_not_at_safepoint(); 735 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 736 737 uint dummy_gc_count_before; 738 uint dummy_gclocker_retry_count = 0; 739 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 740 } 741 742 HeapWord* 743 G1CollectedHeap::mem_allocate(size_t word_size, 744 bool* gc_overhead_limit_was_exceeded) { 745 assert_heap_not_locked_and_not_at_safepoint(); 746 747 // Loop until the allocation is satisfied, or unsatisfied after GC. 748 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 749 uint gc_count_before; 750 751 HeapWord* result = NULL; 752 if (!is_humongous(word_size)) { 753 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 754 } else { 755 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 756 } 757 if (result != NULL) { 758 return result; 759 } 760 761 // Create the garbage collection operation... 762 VM_G1CollectForAllocation op(gc_count_before, word_size); 763 op.set_allocation_context(AllocationContext::current()); 764 765 // ...and get the VM thread to execute it. 766 VMThread::execute(&op); 767 768 if (op.prologue_succeeded() && op.pause_succeeded()) { 769 // If the operation was successful we'll return the result even 770 // if it is NULL. If the allocation attempt failed immediately 771 // after a Full GC, it's unlikely we'll be able to allocate now. 772 HeapWord* result = op.result(); 773 if (result != NULL && !is_humongous(word_size)) { 774 // Allocations that take place on VM operations do not do any 775 // card dirtying and we have to do it here. We only have to do 776 // this for non-humongous allocations, though. 777 dirty_young_block(result, word_size); 778 } 779 return result; 780 } else { 781 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 782 return NULL; 783 } 784 assert(op.result() == NULL, 785 "the result should be NULL if the VM op did not succeed"); 786 } 787 788 // Give a warning if we seem to be looping forever. 789 if ((QueuedAllocationWarningCount > 0) && 790 (try_count % QueuedAllocationWarningCount == 0)) { 791 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 792 } 793 } 794 795 ShouldNotReachHere(); 796 return NULL; 797 } 798 799 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 800 AllocationContext_t context, 801 uint* gc_count_before_ret, 802 uint* gclocker_retry_count_ret) { 803 // Make sure you read the note in attempt_allocation_humongous(). 804 805 assert_heap_not_locked_and_not_at_safepoint(); 806 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 807 "be called for humongous allocation requests"); 808 809 // We should only get here after the first-level allocation attempt 810 // (attempt_allocation()) failed to allocate. 811 812 // We will loop until a) we manage to successfully perform the 813 // allocation or b) we successfully schedule a collection which 814 // fails to perform the allocation. b) is the only case when we'll 815 // return NULL. 816 HeapWord* result = NULL; 817 for (int try_count = 1; /* we'll return */; try_count += 1) { 818 bool should_try_gc; 819 uint gc_count_before; 820 821 { 822 MutexLockerEx x(Heap_lock); 823 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, 824 false /* bot_updates */); 825 if (result != NULL) { 826 return result; 827 } 828 829 // If we reach here, attempt_allocation_locked() above failed to 830 // allocate a new region. So the mutator alloc region should be NULL. 831 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here"); 832 833 if (GC_locker::is_active_and_needs_gc()) { 834 if (g1_policy()->can_expand_young_list()) { 835 // No need for an ergo verbose message here, 836 // can_expand_young_list() does this when it returns true. 837 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size, 838 false /* bot_updates */); 839 if (result != NULL) { 840 return result; 841 } 842 } 843 should_try_gc = false; 844 } else { 845 // The GCLocker may not be active but the GCLocker initiated 846 // GC may not yet have been performed (GCLocker::needs_gc() 847 // returns true). In this case we do not try this GC and 848 // wait until the GCLocker initiated GC is performed, and 849 // then retry the allocation. 850 if (GC_locker::needs_gc()) { 851 should_try_gc = false; 852 } else { 853 // Read the GC count while still holding the Heap_lock. 854 gc_count_before = total_collections(); 855 should_try_gc = true; 856 } 857 } 858 } 859 860 if (should_try_gc) { 861 bool succeeded; 862 result = do_collection_pause(word_size, gc_count_before, &succeeded, 863 GCCause::_g1_inc_collection_pause); 864 if (result != NULL) { 865 assert(succeeded, "only way to get back a non-NULL result"); 866 return result; 867 } 868 869 if (succeeded) { 870 // If we get here we successfully scheduled a collection which 871 // failed to allocate. No point in trying to allocate 872 // further. We'll just return NULL. 873 MutexLockerEx x(Heap_lock); 874 *gc_count_before_ret = total_collections(); 875 return NULL; 876 } 877 } else { 878 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 879 MutexLockerEx x(Heap_lock); 880 *gc_count_before_ret = total_collections(); 881 return NULL; 882 } 883 // The GCLocker is either active or the GCLocker initiated 884 // GC has not yet been performed. Stall until it is and 885 // then retry the allocation. 886 GC_locker::stall_until_clear(); 887 (*gclocker_retry_count_ret) += 1; 888 } 889 890 // We can reach here if we were unsuccessful in scheduling a 891 // collection (because another thread beat us to it) or if we were 892 // stalled due to the GC locker. In either can we should retry the 893 // allocation attempt in case another thread successfully 894 // performed a collection and reclaimed enough space. We do the 895 // first attempt (without holding the Heap_lock) here and the 896 // follow-on attempt will be at the start of the next loop 897 // iteration (after taking the Heap_lock). 898 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size, 899 false /* bot_updates */); 900 if (result != NULL) { 901 return result; 902 } 903 904 // Give a warning if we seem to be looping forever. 905 if ((QueuedAllocationWarningCount > 0) && 906 (try_count % QueuedAllocationWarningCount == 0)) { 907 warning("G1CollectedHeap::attempt_allocation_slow() " 908 "retries %d times", try_count); 909 } 910 } 911 912 ShouldNotReachHere(); 913 return NULL; 914 } 915 916 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 917 uint* gc_count_before_ret, 918 uint* gclocker_retry_count_ret) { 919 // The structure of this method has a lot of similarities to 920 // attempt_allocation_slow(). The reason these two were not merged 921 // into a single one is that such a method would require several "if 922 // allocation is not humongous do this, otherwise do that" 923 // conditional paths which would obscure its flow. In fact, an early 924 // version of this code did use a unified method which was harder to 925 // follow and, as a result, it had subtle bugs that were hard to 926 // track down. So keeping these two methods separate allows each to 927 // be more readable. It will be good to keep these two in sync as 928 // much as possible. 929 930 assert_heap_not_locked_and_not_at_safepoint(); 931 assert(is_humongous(word_size), "attempt_allocation_humongous() " 932 "should only be called for humongous allocations"); 933 934 // Humongous objects can exhaust the heap quickly, so we should check if we 935 // need to start a marking cycle at each humongous object allocation. We do 936 // the check before we do the actual allocation. The reason for doing it 937 // before the allocation is that we avoid having to keep track of the newly 938 // allocated memory while we do a GC. 939 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 940 word_size)) { 941 collect(GCCause::_g1_humongous_allocation); 942 } 943 944 // We will loop until a) we manage to successfully perform the 945 // allocation or b) we successfully schedule a collection which 946 // fails to perform the allocation. b) is the only case when we'll 947 // return NULL. 948 HeapWord* result = NULL; 949 for (int try_count = 1; /* we'll return */; try_count += 1) { 950 bool should_try_gc; 951 uint gc_count_before; 952 953 { 954 MutexLockerEx x(Heap_lock); 955 956 // Given that humongous objects are not allocated in young 957 // regions, we'll first try to do the allocation without doing a 958 // collection hoping that there's enough space in the heap. 959 result = humongous_obj_allocate(word_size, AllocationContext::current()); 960 if (result != NULL) { 961 return result; 962 } 963 964 if (GC_locker::is_active_and_needs_gc()) { 965 should_try_gc = false; 966 } else { 967 // The GCLocker may not be active but the GCLocker initiated 968 // GC may not yet have been performed (GCLocker::needs_gc() 969 // returns true). In this case we do not try this GC and 970 // wait until the GCLocker initiated GC is performed, and 971 // then retry the allocation. 972 if (GC_locker::needs_gc()) { 973 should_try_gc = false; 974 } else { 975 // Read the GC count while still holding the Heap_lock. 976 gc_count_before = total_collections(); 977 should_try_gc = true; 978 } 979 } 980 } 981 982 if (should_try_gc) { 983 // If we failed to allocate the humongous object, we should try to 984 // do a collection pause (if we're allowed) in case it reclaims 985 // enough space for the allocation to succeed after the pause. 986 987 bool succeeded; 988 result = do_collection_pause(word_size, gc_count_before, &succeeded, 989 GCCause::_g1_humongous_allocation); 990 if (result != NULL) { 991 assert(succeeded, "only way to get back a non-NULL result"); 992 return result; 993 } 994 995 if (succeeded) { 996 // If we get here we successfully scheduled a collection which 997 // failed to allocate. No point in trying to allocate 998 // further. We'll just return NULL. 999 MutexLockerEx x(Heap_lock); 1000 *gc_count_before_ret = total_collections(); 1001 return NULL; 1002 } 1003 } else { 1004 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1005 MutexLockerEx x(Heap_lock); 1006 *gc_count_before_ret = total_collections(); 1007 return NULL; 1008 } 1009 // The GCLocker is either active or the GCLocker initiated 1010 // GC has not yet been performed. Stall until it is and 1011 // then retry the allocation. 1012 GC_locker::stall_until_clear(); 1013 (*gclocker_retry_count_ret) += 1; 1014 } 1015 1016 // We can reach here if we were unsuccessful in scheduling a 1017 // collection (because another thread beat us to it) or if we were 1018 // stalled due to the GC locker. In either can we should retry the 1019 // allocation attempt in case another thread successfully 1020 // performed a collection and reclaimed enough space. Give a 1021 // warning if we seem to be looping forever. 1022 1023 if ((QueuedAllocationWarningCount > 0) && 1024 (try_count % QueuedAllocationWarningCount == 0)) { 1025 warning("G1CollectedHeap::attempt_allocation_humongous() " 1026 "retries %d times", try_count); 1027 } 1028 } 1029 1030 ShouldNotReachHere(); 1031 return NULL; 1032 } 1033 1034 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1035 AllocationContext_t context, 1036 bool expect_null_mutator_alloc_region) { 1037 assert_at_safepoint(true /* should_be_vm_thread */); 1038 assert(_allocator->mutator_alloc_region(context)->get() == NULL || 1039 !expect_null_mutator_alloc_region, 1040 "the current alloc region was unexpectedly found to be non-NULL"); 1041 1042 if (!is_humongous(word_size)) { 1043 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, 1044 false /* bot_updates */); 1045 } else { 1046 HeapWord* result = humongous_obj_allocate(word_size, context); 1047 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1048 g1_policy()->set_initiate_conc_mark_if_possible(); 1049 } 1050 return result; 1051 } 1052 1053 ShouldNotReachHere(); 1054 } 1055 1056 class PostMCRemSetClearClosure: public HeapRegionClosure { 1057 G1CollectedHeap* _g1h; 1058 ModRefBarrierSet* _mr_bs; 1059 public: 1060 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1061 _g1h(g1h), _mr_bs(mr_bs) {} 1062 1063 bool doHeapRegion(HeapRegion* r) { 1064 HeapRegionRemSet* hrrs = r->rem_set(); 1065 1066 if (r->is_continues_humongous()) { 1067 // We'll assert that the strong code root list and RSet is empty 1068 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1069 assert(hrrs->occupied() == 0, "RSet should be empty"); 1070 return false; 1071 } 1072 1073 _g1h->reset_gc_time_stamps(r); 1074 hrrs->clear(); 1075 // You might think here that we could clear just the cards 1076 // corresponding to the used region. But no: if we leave a dirty card 1077 // in a region we might allocate into, then it would prevent that card 1078 // from being enqueued, and cause it to be missed. 1079 // Re: the performance cost: we shouldn't be doing full GC anyway! 1080 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1081 1082 return false; 1083 } 1084 }; 1085 1086 void G1CollectedHeap::clear_rsets_post_compaction() { 1087 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1088 heap_region_iterate(&rs_clear); 1089 } 1090 1091 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1092 G1CollectedHeap* _g1h; 1093 UpdateRSOopClosure _cl; 1094 int _worker_i; 1095 public: 1096 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) : 1097 _cl(g1->g1_rem_set(), worker_i), 1098 _worker_i(worker_i), 1099 _g1h(g1) 1100 { } 1101 1102 bool doHeapRegion(HeapRegion* r) { 1103 if (!r->is_continues_humongous()) { 1104 _cl.set_from(r); 1105 r->oop_iterate(&_cl); 1106 } 1107 return false; 1108 } 1109 }; 1110 1111 class ParRebuildRSTask: public AbstractGangTask { 1112 G1CollectedHeap* _g1; 1113 HeapRegionClaimer _hrclaimer; 1114 1115 public: 1116 ParRebuildRSTask(G1CollectedHeap* g1) : 1117 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {} 1118 1119 void work(uint worker_id) { 1120 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1121 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer); 1122 } 1123 }; 1124 1125 class PostCompactionPrinterClosure: public HeapRegionClosure { 1126 private: 1127 G1HRPrinter* _hr_printer; 1128 public: 1129 bool doHeapRegion(HeapRegion* hr) { 1130 assert(!hr->is_young(), "not expecting to find young regions"); 1131 if (hr->is_free()) { 1132 // We only generate output for non-empty regions. 1133 } else if (hr->is_starts_humongous()) { 1134 if (hr->region_num() == 1) { 1135 // single humongous region 1136 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1137 } else { 1138 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1139 } 1140 } else if (hr->is_continues_humongous()) { 1141 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1142 } else if (hr->is_old()) { 1143 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1144 } else { 1145 ShouldNotReachHere(); 1146 } 1147 return false; 1148 } 1149 1150 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1151 : _hr_printer(hr_printer) { } 1152 }; 1153 1154 void G1CollectedHeap::print_hrm_post_compaction() { 1155 PostCompactionPrinterClosure cl(hr_printer()); 1156 heap_region_iterate(&cl); 1157 } 1158 1159 bool G1CollectedHeap::do_collection(bool explicit_gc, 1160 bool clear_all_soft_refs, 1161 size_t word_size) { 1162 assert_at_safepoint(true /* should_be_vm_thread */); 1163 1164 if (GC_locker::check_active_before_gc()) { 1165 return false; 1166 } 1167 1168 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1169 gc_timer->register_gc_start(); 1170 1171 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1172 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1173 1174 SvcGCMarker sgcm(SvcGCMarker::FULL); 1175 ResourceMark rm; 1176 1177 print_heap_before_gc(); 1178 trace_heap_before_gc(gc_tracer); 1179 1180 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1181 1182 verify_region_sets_optional(); 1183 1184 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1185 collector_policy()->should_clear_all_soft_refs(); 1186 1187 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1188 1189 { 1190 IsGCActiveMark x; 1191 1192 // Timing 1193 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); 1194 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1195 1196 { 1197 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id()); 1198 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1199 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1200 1201 g1_policy()->record_full_collection_start(); 1202 1203 // Note: When we have a more flexible GC logging framework that 1204 // allows us to add optional attributes to a GC log record we 1205 // could consider timing and reporting how long we wait in the 1206 // following two methods. 1207 wait_while_free_regions_coming(); 1208 // If we start the compaction before the CM threads finish 1209 // scanning the root regions we might trip them over as we'll 1210 // be moving objects / updating references. So let's wait until 1211 // they are done. By telling them to abort, they should complete 1212 // early. 1213 _cm->root_regions()->abort(); 1214 _cm->root_regions()->wait_until_scan_finished(); 1215 append_secondary_free_list_if_not_empty_with_lock(); 1216 1217 gc_prologue(true); 1218 increment_total_collections(true /* full gc */); 1219 increment_old_marking_cycles_started(); 1220 1221 assert(used() == recalculate_used(), "Should be equal"); 1222 1223 verify_before_gc(); 1224 1225 check_bitmaps("Full GC Start"); 1226 pre_full_gc_dump(gc_timer); 1227 1228 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1229 1230 // Disable discovery and empty the discovered lists 1231 // for the CM ref processor. 1232 ref_processor_cm()->disable_discovery(); 1233 ref_processor_cm()->abandon_partial_discovery(); 1234 ref_processor_cm()->verify_no_references_recorded(); 1235 1236 // Abandon current iterations of concurrent marking and concurrent 1237 // refinement, if any are in progress. We have to do this before 1238 // wait_until_scan_finished() below. 1239 concurrent_mark()->abort(); 1240 1241 // Make sure we'll choose a new allocation region afterwards. 1242 _allocator->release_mutator_alloc_region(); 1243 _allocator->abandon_gc_alloc_regions(); 1244 g1_rem_set()->cleanupHRRS(); 1245 1246 // We should call this after we retire any currently active alloc 1247 // regions so that all the ALLOC / RETIRE events are generated 1248 // before the start GC event. 1249 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1250 1251 // We may have added regions to the current incremental collection 1252 // set between the last GC or pause and now. We need to clear the 1253 // incremental collection set and then start rebuilding it afresh 1254 // after this full GC. 1255 abandon_collection_set(g1_policy()->inc_cset_head()); 1256 g1_policy()->clear_incremental_cset(); 1257 g1_policy()->stop_incremental_cset_building(); 1258 1259 tear_down_region_sets(false /* free_list_only */); 1260 g1_policy()->set_gcs_are_young(true); 1261 1262 // See the comments in g1CollectedHeap.hpp and 1263 // G1CollectedHeap::ref_processing_init() about 1264 // how reference processing currently works in G1. 1265 1266 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1267 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1268 1269 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1270 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1271 1272 ref_processor_stw()->enable_discovery(); 1273 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1274 1275 // Do collection work 1276 { 1277 HandleMark hm; // Discard invalid handles created during gc 1278 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1279 } 1280 1281 assert(num_free_regions() == 0, "we should not have added any free regions"); 1282 rebuild_region_sets(false /* free_list_only */); 1283 1284 // Enqueue any discovered reference objects that have 1285 // not been removed from the discovered lists. 1286 ref_processor_stw()->enqueue_discovered_references(); 1287 1288 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1289 1290 MemoryService::track_memory_usage(); 1291 1292 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1293 ref_processor_stw()->verify_no_references_recorded(); 1294 1295 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1296 ClassLoaderDataGraph::purge(); 1297 MetaspaceAux::verify_metrics(); 1298 1299 // Note: since we've just done a full GC, concurrent 1300 // marking is no longer active. Therefore we need not 1301 // re-enable reference discovery for the CM ref processor. 1302 // That will be done at the start of the next marking cycle. 1303 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1304 ref_processor_cm()->verify_no_references_recorded(); 1305 1306 reset_gc_time_stamp(); 1307 // Since everything potentially moved, we will clear all remembered 1308 // sets, and clear all cards. Later we will rebuild remembered 1309 // sets. We will also reset the GC time stamps of the regions. 1310 clear_rsets_post_compaction(); 1311 check_gc_time_stamps(); 1312 1313 // Resize the heap if necessary. 1314 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1315 1316 if (_hr_printer.is_active()) { 1317 // We should do this after we potentially resize the heap so 1318 // that all the COMMIT / UNCOMMIT events are generated before 1319 // the end GC event. 1320 1321 print_hrm_post_compaction(); 1322 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1323 } 1324 1325 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1326 if (hot_card_cache->use_cache()) { 1327 hot_card_cache->reset_card_counts(); 1328 hot_card_cache->reset_hot_cache(); 1329 } 1330 1331 // Rebuild remembered sets of all regions. 1332 uint n_workers = 1333 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1334 workers()->active_workers(), 1335 Threads::number_of_non_daemon_threads()); 1336 assert(UseDynamicNumberOfGCThreads || 1337 n_workers == workers()->total_workers(), 1338 "If not dynamic should be using all the workers"); 1339 workers()->set_active_workers(n_workers); 1340 // Set parallel threads in the heap (_n_par_threads) only 1341 // before a parallel phase and always reset it to 0 after 1342 // the phase so that the number of parallel threads does 1343 // no get carried forward to a serial phase where there 1344 // may be code that is "possibly_parallel". 1345 set_par_threads(n_workers); 1346 1347 ParRebuildRSTask rebuild_rs_task(this); 1348 assert(UseDynamicNumberOfGCThreads || 1349 workers()->active_workers() == workers()->total_workers(), 1350 "Unless dynamic should use total workers"); 1351 // Use the most recent number of active workers 1352 assert(workers()->active_workers() > 0, 1353 "Active workers not properly set"); 1354 set_par_threads(workers()->active_workers()); 1355 workers()->run_task(&rebuild_rs_task); 1356 set_par_threads(0); 1357 1358 // Rebuild the strong code root lists for each region 1359 rebuild_strong_code_roots(); 1360 1361 if (true) { // FIXME 1362 MetaspaceGC::compute_new_size(); 1363 } 1364 1365 #ifdef TRACESPINNING 1366 ParallelTaskTerminator::print_termination_counts(); 1367 #endif 1368 1369 // Discard all rset updates 1370 JavaThread::dirty_card_queue_set().abandon_logs(); 1371 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1372 1373 _young_list->reset_sampled_info(); 1374 // At this point there should be no regions in the 1375 // entire heap tagged as young. 1376 assert(check_young_list_empty(true /* check_heap */), 1377 "young list should be empty at this point"); 1378 1379 // Update the number of full collections that have been completed. 1380 increment_old_marking_cycles_completed(false /* concurrent */); 1381 1382 _hrm.verify_optional(); 1383 verify_region_sets_optional(); 1384 1385 verify_after_gc(); 1386 1387 // Clear the previous marking bitmap, if needed for bitmap verification. 1388 // Note we cannot do this when we clear the next marking bitmap in 1389 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1390 // objects marked during a full GC against the previous bitmap. 1391 // But we need to clear it before calling check_bitmaps below since 1392 // the full GC has compacted objects and updated TAMS but not updated 1393 // the prev bitmap. 1394 if (G1VerifyBitmaps) { 1395 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1396 } 1397 check_bitmaps("Full GC End"); 1398 1399 // Start a new incremental collection set for the next pause 1400 assert(g1_policy()->collection_set() == NULL, "must be"); 1401 g1_policy()->start_incremental_cset_building(); 1402 1403 clear_cset_fast_test(); 1404 1405 _allocator->init_mutator_alloc_region(); 1406 1407 g1_policy()->record_full_collection_end(); 1408 1409 if (G1Log::fine()) { 1410 g1_policy()->print_heap_transition(); 1411 } 1412 1413 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1414 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1415 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1416 // before any GC notifications are raised. 1417 g1mm()->update_sizes(); 1418 1419 gc_epilogue(true); 1420 } 1421 1422 if (G1Log::finer()) { 1423 g1_policy()->print_detailed_heap_transition(true /* full */); 1424 } 1425 1426 print_heap_after_gc(); 1427 trace_heap_after_gc(gc_tracer); 1428 1429 post_full_gc_dump(gc_timer); 1430 1431 gc_timer->register_gc_end(); 1432 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1433 } 1434 1435 return true; 1436 } 1437 1438 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1439 // do_collection() will return whether it succeeded in performing 1440 // the GC. Currently, there is no facility on the 1441 // do_full_collection() API to notify the caller than the collection 1442 // did not succeed (e.g., because it was locked out by the GC 1443 // locker). So, right now, we'll ignore the return value. 1444 bool dummy = do_collection(true, /* explicit_gc */ 1445 clear_all_soft_refs, 1446 0 /* word_size */); 1447 } 1448 1449 // This code is mostly copied from TenuredGeneration. 1450 void 1451 G1CollectedHeap:: 1452 resize_if_necessary_after_full_collection(size_t word_size) { 1453 // Include the current allocation, if any, and bytes that will be 1454 // pre-allocated to support collections, as "used". 1455 const size_t used_after_gc = used(); 1456 const size_t capacity_after_gc = capacity(); 1457 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1458 1459 // This is enforced in arguments.cpp. 1460 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1461 "otherwise the code below doesn't make sense"); 1462 1463 // We don't have floating point command-line arguments 1464 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1465 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1466 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1467 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1468 1469 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1470 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1471 1472 // We have to be careful here as these two calculations can overflow 1473 // 32-bit size_t's. 1474 double used_after_gc_d = (double) used_after_gc; 1475 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1476 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1477 1478 // Let's make sure that they are both under the max heap size, which 1479 // by default will make them fit into a size_t. 1480 double desired_capacity_upper_bound = (double) max_heap_size; 1481 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1482 desired_capacity_upper_bound); 1483 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1484 desired_capacity_upper_bound); 1485 1486 // We can now safely turn them into size_t's. 1487 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1488 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1489 1490 // This assert only makes sense here, before we adjust them 1491 // with respect to the min and max heap size. 1492 assert(minimum_desired_capacity <= maximum_desired_capacity, 1493 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1494 "maximum_desired_capacity = "SIZE_FORMAT, 1495 minimum_desired_capacity, maximum_desired_capacity)); 1496 1497 // Should not be greater than the heap max size. No need to adjust 1498 // it with respect to the heap min size as it's a lower bound (i.e., 1499 // we'll try to make the capacity larger than it, not smaller). 1500 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1501 // Should not be less than the heap min size. No need to adjust it 1502 // with respect to the heap max size as it's an upper bound (i.e., 1503 // we'll try to make the capacity smaller than it, not greater). 1504 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1505 1506 if (capacity_after_gc < minimum_desired_capacity) { 1507 // Don't expand unless it's significant 1508 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1509 ergo_verbose4(ErgoHeapSizing, 1510 "attempt heap expansion", 1511 ergo_format_reason("capacity lower than " 1512 "min desired capacity after Full GC") 1513 ergo_format_byte("capacity") 1514 ergo_format_byte("occupancy") 1515 ergo_format_byte_perc("min desired capacity"), 1516 capacity_after_gc, used_after_gc, 1517 minimum_desired_capacity, (double) MinHeapFreeRatio); 1518 expand(expand_bytes); 1519 1520 // No expansion, now see if we want to shrink 1521 } else if (capacity_after_gc > maximum_desired_capacity) { 1522 // Capacity too large, compute shrinking size 1523 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1524 ergo_verbose4(ErgoHeapSizing, 1525 "attempt heap shrinking", 1526 ergo_format_reason("capacity higher than " 1527 "max desired capacity after Full GC") 1528 ergo_format_byte("capacity") 1529 ergo_format_byte("occupancy") 1530 ergo_format_byte_perc("max desired capacity"), 1531 capacity_after_gc, used_after_gc, 1532 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1533 shrink(shrink_bytes); 1534 } 1535 } 1536 1537 1538 HeapWord* 1539 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1540 AllocationContext_t context, 1541 bool* succeeded) { 1542 assert_at_safepoint(true /* should_be_vm_thread */); 1543 1544 *succeeded = true; 1545 // Let's attempt the allocation first. 1546 HeapWord* result = 1547 attempt_allocation_at_safepoint(word_size, 1548 context, 1549 false /* expect_null_mutator_alloc_region */); 1550 if (result != NULL) { 1551 assert(*succeeded, "sanity"); 1552 return result; 1553 } 1554 1555 // In a G1 heap, we're supposed to keep allocation from failing by 1556 // incremental pauses. Therefore, at least for now, we'll favor 1557 // expansion over collection. (This might change in the future if we can 1558 // do something smarter than full collection to satisfy a failed alloc.) 1559 result = expand_and_allocate(word_size, context); 1560 if (result != NULL) { 1561 assert(*succeeded, "sanity"); 1562 return result; 1563 } 1564 1565 // Expansion didn't work, we'll try to do a Full GC. 1566 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1567 false, /* clear_all_soft_refs */ 1568 word_size); 1569 if (!gc_succeeded) { 1570 *succeeded = false; 1571 return NULL; 1572 } 1573 1574 // Retry the allocation 1575 result = attempt_allocation_at_safepoint(word_size, 1576 context, 1577 true /* expect_null_mutator_alloc_region */); 1578 if (result != NULL) { 1579 assert(*succeeded, "sanity"); 1580 return result; 1581 } 1582 1583 // Then, try a Full GC that will collect all soft references. 1584 gc_succeeded = do_collection(false, /* explicit_gc */ 1585 true, /* clear_all_soft_refs */ 1586 word_size); 1587 if (!gc_succeeded) { 1588 *succeeded = false; 1589 return NULL; 1590 } 1591 1592 // Retry the allocation once more 1593 result = attempt_allocation_at_safepoint(word_size, 1594 context, 1595 true /* expect_null_mutator_alloc_region */); 1596 if (result != NULL) { 1597 assert(*succeeded, "sanity"); 1598 return result; 1599 } 1600 1601 assert(!collector_policy()->should_clear_all_soft_refs(), 1602 "Flag should have been handled and cleared prior to this point"); 1603 1604 // What else? We might try synchronous finalization later. If the total 1605 // space available is large enough for the allocation, then a more 1606 // complete compaction phase than we've tried so far might be 1607 // appropriate. 1608 assert(*succeeded, "sanity"); 1609 return NULL; 1610 } 1611 1612 // Attempting to expand the heap sufficiently 1613 // to support an allocation of the given "word_size". If 1614 // successful, perform the allocation and return the address of the 1615 // allocated block, or else "NULL". 1616 1617 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1618 assert_at_safepoint(true /* should_be_vm_thread */); 1619 1620 verify_region_sets_optional(); 1621 1622 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1623 ergo_verbose1(ErgoHeapSizing, 1624 "attempt heap expansion", 1625 ergo_format_reason("allocation request failed") 1626 ergo_format_byte("allocation request"), 1627 word_size * HeapWordSize); 1628 if (expand(expand_bytes)) { 1629 _hrm.verify_optional(); 1630 verify_region_sets_optional(); 1631 return attempt_allocation_at_safepoint(word_size, 1632 context, 1633 false /* expect_null_mutator_alloc_region */); 1634 } 1635 return NULL; 1636 } 1637 1638 bool G1CollectedHeap::expand(size_t expand_bytes) { 1639 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1640 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1641 HeapRegion::GrainBytes); 1642 ergo_verbose2(ErgoHeapSizing, 1643 "expand the heap", 1644 ergo_format_byte("requested expansion amount") 1645 ergo_format_byte("attempted expansion amount"), 1646 expand_bytes, aligned_expand_bytes); 1647 1648 if (is_maximal_no_gc()) { 1649 ergo_verbose0(ErgoHeapSizing, 1650 "did not expand the heap", 1651 ergo_format_reason("heap already fully expanded")); 1652 return false; 1653 } 1654 1655 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1656 assert(regions_to_expand > 0, "Must expand by at least one region"); 1657 1658 uint expanded_by = _hrm.expand_by(regions_to_expand); 1659 1660 if (expanded_by > 0) { 1661 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1662 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1663 g1_policy()->record_new_heap_size(num_regions()); 1664 } else { 1665 ergo_verbose0(ErgoHeapSizing, 1666 "did not expand the heap", 1667 ergo_format_reason("heap expansion operation failed")); 1668 // The expansion of the virtual storage space was unsuccessful. 1669 // Let's see if it was because we ran out of swap. 1670 if (G1ExitOnExpansionFailure && 1671 _hrm.available() >= regions_to_expand) { 1672 // We had head room... 1673 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1674 } 1675 } 1676 return regions_to_expand > 0; 1677 } 1678 1679 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1680 size_t aligned_shrink_bytes = 1681 ReservedSpace::page_align_size_down(shrink_bytes); 1682 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1683 HeapRegion::GrainBytes); 1684 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1685 1686 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1687 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1688 1689 ergo_verbose3(ErgoHeapSizing, 1690 "shrink the heap", 1691 ergo_format_byte("requested shrinking amount") 1692 ergo_format_byte("aligned shrinking amount") 1693 ergo_format_byte("attempted shrinking amount"), 1694 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1695 if (num_regions_removed > 0) { 1696 g1_policy()->record_new_heap_size(num_regions()); 1697 } else { 1698 ergo_verbose0(ErgoHeapSizing, 1699 "did not shrink the heap", 1700 ergo_format_reason("heap shrinking operation failed")); 1701 } 1702 } 1703 1704 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1705 verify_region_sets_optional(); 1706 1707 // We should only reach here at the end of a Full GC which means we 1708 // should not not be holding to any GC alloc regions. The method 1709 // below will make sure of that and do any remaining clean up. 1710 _allocator->abandon_gc_alloc_regions(); 1711 1712 // Instead of tearing down / rebuilding the free lists here, we 1713 // could instead use the remove_all_pending() method on free_list to 1714 // remove only the ones that we need to remove. 1715 tear_down_region_sets(true /* free_list_only */); 1716 shrink_helper(shrink_bytes); 1717 rebuild_region_sets(true /* free_list_only */); 1718 1719 _hrm.verify_optional(); 1720 verify_region_sets_optional(); 1721 } 1722 1723 // Public methods. 1724 1725 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1726 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1727 #endif // _MSC_VER 1728 1729 1730 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1731 SharedHeap(), 1732 _g1_policy(policy_), 1733 _dirty_card_queue_set(false), 1734 _into_cset_dirty_card_queue_set(false), 1735 _is_alive_closure_cm(this), 1736 _is_alive_closure_stw(this), 1737 _ref_processor_cm(NULL), 1738 _ref_processor_stw(NULL), 1739 _bot_shared(NULL), 1740 _evac_failure_scan_stack(NULL), 1741 _mark_in_progress(false), 1742 _cg1r(NULL), 1743 _g1mm(NULL), 1744 _refine_cte_cl(NULL), 1745 _full_collection(false), 1746 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1747 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1748 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1749 _humongous_is_live(), 1750 _has_humongous_reclaim_candidates(false), 1751 _free_regions_coming(false), 1752 _young_list(new YoungList(this)), 1753 _gc_time_stamp(0), 1754 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1755 _old_plab_stats(OldPLABSize, PLABWeight), 1756 _expand_heap_after_alloc_failure(true), 1757 _surviving_young_words(NULL), 1758 _old_marking_cycles_started(0), 1759 _old_marking_cycles_completed(0), 1760 _concurrent_cycle_started(false), 1761 _heap_summary_sent(false), 1762 _in_cset_fast_test(), 1763 _dirty_cards_region_list(NULL), 1764 _worker_cset_start_region(NULL), 1765 _worker_cset_start_region_time_stamp(NULL), 1766 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1767 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1768 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1769 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1770 1771 _g1h = this; 1772 1773 _allocator = G1Allocator::create_allocator(_g1h); 1774 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1775 1776 int n_queues = MAX2((int)ParallelGCThreads, 1); 1777 _task_queues = new RefToScanQueueSet(n_queues); 1778 1779 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1780 assert(n_rem_sets > 0, "Invariant."); 1781 1782 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1783 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC); 1784 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1785 1786 for (int i = 0; i < n_queues; i++) { 1787 RefToScanQueue* q = new RefToScanQueue(); 1788 q->initialize(); 1789 _task_queues->register_queue(i, q); 1790 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1791 } 1792 clear_cset_start_regions(); 1793 1794 // Initialize the G1EvacuationFailureALot counters and flags. 1795 NOT_PRODUCT(reset_evacuation_should_fail();) 1796 1797 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1798 } 1799 1800 jint G1CollectedHeap::initialize() { 1801 CollectedHeap::pre_initialize(); 1802 os::enable_vtime(); 1803 1804 G1Log::init(); 1805 1806 // Necessary to satisfy locking discipline assertions. 1807 1808 MutexLocker x(Heap_lock); 1809 1810 // We have to initialize the printer before committing the heap, as 1811 // it will be used then. 1812 _hr_printer.set_active(G1PrintHeapRegions); 1813 1814 // While there are no constraints in the GC code that HeapWordSize 1815 // be any particular value, there are multiple other areas in the 1816 // system which believe this to be true (e.g. oop->object_size in some 1817 // cases incorrectly returns the size in wordSize units rather than 1818 // HeapWordSize). 1819 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1820 1821 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1822 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1823 size_t heap_alignment = collector_policy()->heap_alignment(); 1824 1825 // Ensure that the sizes are properly aligned. 1826 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1827 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1828 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1829 1830 _refine_cte_cl = new RefineCardTableEntryClosure(); 1831 1832 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl); 1833 1834 // Reserve the maximum. 1835 1836 // When compressed oops are enabled, the preferred heap base 1837 // is calculated by subtracting the requested size from the 1838 // 32Gb boundary and using the result as the base address for 1839 // heap reservation. If the requested size is not aligned to 1840 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1841 // into the ReservedHeapSpace constructor) then the actual 1842 // base of the reserved heap may end up differing from the 1843 // address that was requested (i.e. the preferred heap base). 1844 // If this happens then we could end up using a non-optimal 1845 // compressed oops mode. 1846 1847 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1848 heap_alignment); 1849 1850 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1851 1852 // Create the barrier set for the entire reserved region. 1853 G1SATBCardTableLoggingModRefBS* bs 1854 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 1855 bs->initialize(); 1856 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 1857 set_barrier_set(bs); 1858 1859 // Also create a G1 rem set. 1860 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 1861 1862 // Carve out the G1 part of the heap. 1863 1864 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1865 G1RegionToSpaceMapper* heap_storage = 1866 G1RegionToSpaceMapper::create_mapper(g1_rs, 1867 UseLargePages ? os::large_page_size() : os::vm_page_size(), 1868 HeapRegion::GrainBytes, 1869 1, 1870 mtJavaHeap); 1871 heap_storage->set_mapping_changed_listener(&_listener); 1872 1873 // Reserve space for the block offset table. We do not support automatic uncommit 1874 // for the card table at this time. BOT only. 1875 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize)); 1876 G1RegionToSpaceMapper* bot_storage = 1877 G1RegionToSpaceMapper::create_mapper(bot_rs, 1878 os::vm_page_size(), 1879 HeapRegion::GrainBytes, 1880 G1BlockOffsetSharedArray::N_bytes, 1881 mtGC); 1882 1883 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 1884 G1RegionToSpaceMapper* cardtable_storage = 1885 G1RegionToSpaceMapper::create_mapper(cardtable_rs, 1886 os::vm_page_size(), 1887 HeapRegion::GrainBytes, 1888 G1BlockOffsetSharedArray::N_bytes, 1889 mtGC); 1890 1891 // Reserve space for the card counts table. 1892 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize)); 1893 G1RegionToSpaceMapper* card_counts_storage = 1894 G1RegionToSpaceMapper::create_mapper(card_counts_rs, 1895 os::vm_page_size(), 1896 HeapRegion::GrainBytes, 1897 G1BlockOffsetSharedArray::N_bytes, 1898 mtGC); 1899 1900 // Reserve space for prev and next bitmap. 1901 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); 1902 1903 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size)); 1904 G1RegionToSpaceMapper* prev_bitmap_storage = 1905 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs, 1906 os::vm_page_size(), 1907 HeapRegion::GrainBytes, 1908 CMBitMap::mark_distance(), 1909 mtGC); 1910 1911 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size)); 1912 G1RegionToSpaceMapper* next_bitmap_storage = 1913 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs, 1914 os::vm_page_size(), 1915 HeapRegion::GrainBytes, 1916 CMBitMap::mark_distance(), 1917 mtGC); 1918 1919 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1920 g1_barrier_set()->initialize(cardtable_storage); 1921 // Do later initialization work for concurrent refinement. 1922 _cg1r->init(card_counts_storage); 1923 1924 // 6843694 - ensure that the maximum region index can fit 1925 // in the remembered set structures. 1926 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1927 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1928 1929 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1930 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1931 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1932 "too many cards per region"); 1933 1934 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1935 1936 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage); 1937 1938 _g1h = this; 1939 1940 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes); 1941 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes); 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 void G1CollectedHeap::clear_humongous_is_live_table() { 2030 guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true"); 2031 _humongous_is_live.clear(); 2032 } 2033 2034 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2035 return HeapRegion::max_region_size(); 2036 } 2037 2038 void G1CollectedHeap::post_initialize() { 2039 CollectedHeap::post_initialize(); 2040 ref_processing_init(); 2041 } 2042 2043 void G1CollectedHeap::ref_processing_init() { 2044 // Reference processing in G1 currently works as follows: 2045 // 2046 // * There are two reference processor instances. One is 2047 // used to record and process discovered references 2048 // during concurrent marking; the other is used to 2049 // record and process references during STW pauses 2050 // (both full and incremental). 2051 // * Both ref processors need to 'span' the entire heap as 2052 // the regions in the collection set may be dotted around. 2053 // 2054 // * For the concurrent marking ref processor: 2055 // * Reference discovery is enabled at initial marking. 2056 // * Reference discovery is disabled and the discovered 2057 // references processed etc during remarking. 2058 // * Reference discovery is MT (see below). 2059 // * Reference discovery requires a barrier (see below). 2060 // * Reference processing may or may not be MT 2061 // (depending on the value of ParallelRefProcEnabled 2062 // and ParallelGCThreads). 2063 // * A full GC disables reference discovery by the CM 2064 // ref processor and abandons any entries on it's 2065 // discovered lists. 2066 // 2067 // * For the STW processor: 2068 // * Non MT discovery is enabled at the start of a full GC. 2069 // * Processing and enqueueing during a full GC is non-MT. 2070 // * During a full GC, references are processed after marking. 2071 // 2072 // * Discovery (may or may not be MT) is enabled at the start 2073 // of an incremental evacuation pause. 2074 // * References are processed near the end of a STW evacuation pause. 2075 // * For both types of GC: 2076 // * Discovery is atomic - i.e. not concurrent. 2077 // * Reference discovery will not need a barrier. 2078 2079 MemRegion mr = reserved_region(); 2080 2081 // Concurrent Mark ref processor 2082 _ref_processor_cm = 2083 new ReferenceProcessor(mr, // span 2084 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2085 // mt processing 2086 (int) ParallelGCThreads, 2087 // degree of mt processing 2088 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2089 // mt discovery 2090 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2091 // degree of mt discovery 2092 false, 2093 // Reference discovery is not atomic 2094 &_is_alive_closure_cm); 2095 // is alive closure 2096 // (for efficiency/performance) 2097 2098 // STW ref processor 2099 _ref_processor_stw = 2100 new ReferenceProcessor(mr, // span 2101 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2102 // mt processing 2103 MAX2((int)ParallelGCThreads, 1), 2104 // degree of mt processing 2105 (ParallelGCThreads > 1), 2106 // mt discovery 2107 MAX2((int)ParallelGCThreads, 1), 2108 // degree of mt discovery 2109 true, 2110 // Reference discovery is atomic 2111 &_is_alive_closure_stw); 2112 // is alive closure 2113 // (for efficiency/performance) 2114 } 2115 2116 size_t G1CollectedHeap::capacity() const { 2117 return _hrm.length() * HeapRegion::GrainBytes; 2118 } 2119 2120 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2121 assert(!hr->is_continues_humongous(), "pre-condition"); 2122 hr->reset_gc_time_stamp(); 2123 if (hr->is_starts_humongous()) { 2124 uint first_index = hr->hrm_index() + 1; 2125 uint last_index = hr->last_hc_index(); 2126 for (uint i = first_index; i < last_index; i += 1) { 2127 HeapRegion* chr = region_at(i); 2128 assert(chr->is_continues_humongous(), "sanity"); 2129 chr->reset_gc_time_stamp(); 2130 } 2131 } 2132 } 2133 2134 #ifndef PRODUCT 2135 2136 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2137 private: 2138 unsigned _gc_time_stamp; 2139 bool _failures; 2140 2141 public: 2142 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2143 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2144 2145 virtual bool doHeapRegion(HeapRegion* hr) { 2146 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2147 if (_gc_time_stamp != region_gc_time_stamp) { 2148 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2149 "expected %d", HR_FORMAT_PARAMS(hr), 2150 region_gc_time_stamp, _gc_time_stamp); 2151 _failures = true; 2152 } 2153 return false; 2154 } 2155 2156 bool failures() { return _failures; } 2157 }; 2158 2159 void G1CollectedHeap::check_gc_time_stamps() { 2160 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2161 heap_region_iterate(&cl); 2162 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2163 } 2164 #endif // PRODUCT 2165 2166 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2167 DirtyCardQueue* into_cset_dcq, 2168 bool concurrent, 2169 uint worker_i) { 2170 // Clean cards in the hot card cache 2171 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2172 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2173 2174 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2175 size_t n_completed_buffers = 0; 2176 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2177 n_completed_buffers++; 2178 } 2179 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 2180 dcqs.clear_n_completed_buffers(); 2181 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2182 } 2183 2184 2185 // Computes the sum of the storage used by the various regions. 2186 size_t G1CollectedHeap::used() const { 2187 return _allocator->used(); 2188 } 2189 2190 size_t G1CollectedHeap::used_unlocked() const { 2191 return _allocator->used_unlocked(); 2192 } 2193 2194 class SumUsedClosure: public HeapRegionClosure { 2195 size_t _used; 2196 public: 2197 SumUsedClosure() : _used(0) {} 2198 bool doHeapRegion(HeapRegion* r) { 2199 if (!r->is_continues_humongous()) { 2200 _used += r->used(); 2201 } 2202 return false; 2203 } 2204 size_t result() { return _used; } 2205 }; 2206 2207 size_t G1CollectedHeap::recalculate_used() const { 2208 double recalculate_used_start = os::elapsedTime(); 2209 2210 SumUsedClosure blk; 2211 heap_region_iterate(&blk); 2212 2213 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2214 return blk.result(); 2215 } 2216 2217 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2218 switch (cause) { 2219 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2220 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2221 case GCCause::_g1_humongous_allocation: return true; 2222 case GCCause::_update_allocation_context_stats_inc: return true; 2223 case GCCause::_wb_conc_mark: return true; 2224 default: return false; 2225 } 2226 } 2227 2228 #ifndef PRODUCT 2229 void G1CollectedHeap::allocate_dummy_regions() { 2230 // Let's fill up most of the region 2231 size_t word_size = HeapRegion::GrainWords - 1024; 2232 // And as a result the region we'll allocate will be humongous. 2233 guarantee(is_humongous(word_size), "sanity"); 2234 2235 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2236 // Let's use the existing mechanism for the allocation 2237 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2238 AllocationContext::system()); 2239 if (dummy_obj != NULL) { 2240 MemRegion mr(dummy_obj, word_size); 2241 CollectedHeap::fill_with_object(mr); 2242 } else { 2243 // If we can't allocate once, we probably cannot allocate 2244 // again. Let's get out of the loop. 2245 break; 2246 } 2247 } 2248 } 2249 #endif // !PRODUCT 2250 2251 void G1CollectedHeap::increment_old_marking_cycles_started() { 2252 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2253 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2254 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2255 _old_marking_cycles_started, _old_marking_cycles_completed)); 2256 2257 _old_marking_cycles_started++; 2258 } 2259 2260 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2261 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2262 2263 // We assume that if concurrent == true, then the caller is a 2264 // concurrent thread that was joined the Suspendible Thread 2265 // Set. If there's ever a cheap way to check this, we should add an 2266 // assert here. 2267 2268 // Given that this method is called at the end of a Full GC or of a 2269 // concurrent cycle, and those can be nested (i.e., a Full GC can 2270 // interrupt a concurrent cycle), the number of full collections 2271 // completed should be either one (in the case where there was no 2272 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2273 // behind the number of full collections started. 2274 2275 // This is the case for the inner caller, i.e. a Full GC. 2276 assert(concurrent || 2277 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2278 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2279 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2280 "is inconsistent with _old_marking_cycles_completed = %u", 2281 _old_marking_cycles_started, _old_marking_cycles_completed)); 2282 2283 // This is the case for the outer caller, i.e. the concurrent cycle. 2284 assert(!concurrent || 2285 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2286 err_msg("for outer caller (concurrent cycle): " 2287 "_old_marking_cycles_started = %u " 2288 "is inconsistent with _old_marking_cycles_completed = %u", 2289 _old_marking_cycles_started, _old_marking_cycles_completed)); 2290 2291 _old_marking_cycles_completed += 1; 2292 2293 // We need to clear the "in_progress" flag in the CM thread before 2294 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2295 // is set) so that if a waiter requests another System.gc() it doesn't 2296 // incorrectly see that a marking cycle is still in progress. 2297 if (concurrent) { 2298 _cmThread->clear_in_progress(); 2299 } 2300 2301 // This notify_all() will ensure that a thread that called 2302 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2303 // and it's waiting for a full GC to finish will be woken up. It is 2304 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2305 FullGCCount_lock->notify_all(); 2306 } 2307 2308 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2309 _concurrent_cycle_started = true; 2310 _gc_timer_cm->register_gc_start(start_time); 2311 2312 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2313 trace_heap_before_gc(_gc_tracer_cm); 2314 } 2315 2316 void G1CollectedHeap::register_concurrent_cycle_end() { 2317 if (_concurrent_cycle_started) { 2318 if (_cm->has_aborted()) { 2319 _gc_tracer_cm->report_concurrent_mode_failure(); 2320 } 2321 2322 _gc_timer_cm->register_gc_end(); 2323 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2324 2325 // Clear state variables to prepare for the next concurrent cycle. 2326 _concurrent_cycle_started = false; 2327 _heap_summary_sent = false; 2328 } 2329 } 2330 2331 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2332 if (_concurrent_cycle_started) { 2333 // This function can be called when: 2334 // the cleanup pause is run 2335 // the concurrent cycle is aborted before the cleanup pause. 2336 // the concurrent cycle is aborted after the cleanup pause, 2337 // but before the concurrent cycle end has been registered. 2338 // Make sure that we only send the heap information once. 2339 if (!_heap_summary_sent) { 2340 trace_heap_after_gc(_gc_tracer_cm); 2341 _heap_summary_sent = true; 2342 } 2343 } 2344 } 2345 2346 G1YCType G1CollectedHeap::yc_type() { 2347 bool is_young = g1_policy()->gcs_are_young(); 2348 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2349 bool is_during_mark = mark_in_progress(); 2350 2351 if (is_initial_mark) { 2352 return InitialMark; 2353 } else if (is_during_mark) { 2354 return DuringMark; 2355 } else if (is_young) { 2356 return Normal; 2357 } else { 2358 return Mixed; 2359 } 2360 } 2361 2362 void G1CollectedHeap::collect(GCCause::Cause cause) { 2363 assert_heap_not_locked(); 2364 2365 uint gc_count_before; 2366 uint old_marking_count_before; 2367 uint full_gc_count_before; 2368 bool retry_gc; 2369 2370 do { 2371 retry_gc = false; 2372 2373 { 2374 MutexLocker ml(Heap_lock); 2375 2376 // Read the GC count while holding the Heap_lock 2377 gc_count_before = total_collections(); 2378 full_gc_count_before = total_full_collections(); 2379 old_marking_count_before = _old_marking_cycles_started; 2380 } 2381 2382 if (should_do_concurrent_full_gc(cause)) { 2383 // Schedule an initial-mark evacuation pause that will start a 2384 // concurrent cycle. We're setting word_size to 0 which means that 2385 // we are not requesting a post-GC allocation. 2386 VM_G1IncCollectionPause op(gc_count_before, 2387 0, /* word_size */ 2388 true, /* should_initiate_conc_mark */ 2389 g1_policy()->max_pause_time_ms(), 2390 cause); 2391 op.set_allocation_context(AllocationContext::current()); 2392 2393 VMThread::execute(&op); 2394 if (!op.pause_succeeded()) { 2395 if (old_marking_count_before == _old_marking_cycles_started) { 2396 retry_gc = op.should_retry_gc(); 2397 } else { 2398 // A Full GC happened while we were trying to schedule the 2399 // initial-mark GC. No point in starting a new cycle given 2400 // that the whole heap was collected anyway. 2401 } 2402 2403 if (retry_gc) { 2404 if (GC_locker::is_active_and_needs_gc()) { 2405 GC_locker::stall_until_clear(); 2406 } 2407 } 2408 } 2409 } else { 2410 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2411 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2412 2413 // Schedule a standard evacuation pause. We're setting word_size 2414 // to 0 which means that we are not requesting a post-GC allocation. 2415 VM_G1IncCollectionPause op(gc_count_before, 2416 0, /* word_size */ 2417 false, /* should_initiate_conc_mark */ 2418 g1_policy()->max_pause_time_ms(), 2419 cause); 2420 VMThread::execute(&op); 2421 } else { 2422 // Schedule a Full GC. 2423 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2424 VMThread::execute(&op); 2425 } 2426 } 2427 } while (retry_gc); 2428 } 2429 2430 bool G1CollectedHeap::is_in(const void* p) const { 2431 if (_hrm.reserved().contains(p)) { 2432 // Given that we know that p is in the reserved space, 2433 // heap_region_containing_raw() should successfully 2434 // return the containing region. 2435 HeapRegion* hr = heap_region_containing_raw(p); 2436 return hr->is_in(p); 2437 } else { 2438 return false; 2439 } 2440 } 2441 2442 #ifdef ASSERT 2443 bool G1CollectedHeap::is_in_exact(const void* p) const { 2444 bool contains = reserved_region().contains(p); 2445 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2446 if (contains && available) { 2447 return true; 2448 } else { 2449 return false; 2450 } 2451 } 2452 #endif 2453 2454 // Iteration functions. 2455 2456 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2457 2458 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2459 ExtendedOopClosure* _cl; 2460 public: 2461 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2462 bool doHeapRegion(HeapRegion* r) { 2463 if (!r->is_continues_humongous()) { 2464 r->oop_iterate(_cl); 2465 } 2466 return false; 2467 } 2468 }; 2469 2470 // Iterates an ObjectClosure over all objects within a HeapRegion. 2471 2472 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2473 ObjectClosure* _cl; 2474 public: 2475 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2476 bool doHeapRegion(HeapRegion* r) { 2477 if (!r->is_continues_humongous()) { 2478 r->object_iterate(_cl); 2479 } 2480 return false; 2481 } 2482 }; 2483 2484 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2485 IterateObjectClosureRegionClosure blk(cl); 2486 heap_region_iterate(&blk); 2487 } 2488 2489 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2490 _hrm.iterate(cl); 2491 } 2492 2493 void 2494 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, 2495 uint worker_id, 2496 HeapRegionClaimer *hrclaimer, 2497 bool concurrent) const { 2498 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); 2499 } 2500 2501 // Clear the cached CSet starting regions and (more importantly) 2502 // the time stamps. Called when we reset the GC time stamp. 2503 void G1CollectedHeap::clear_cset_start_regions() { 2504 assert(_worker_cset_start_region != NULL, "sanity"); 2505 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2506 2507 int n_queues = MAX2((int)ParallelGCThreads, 1); 2508 for (int i = 0; i < n_queues; i++) { 2509 _worker_cset_start_region[i] = NULL; 2510 _worker_cset_start_region_time_stamp[i] = 0; 2511 } 2512 } 2513 2514 // Given the id of a worker, obtain or calculate a suitable 2515 // starting region for iterating over the current collection set. 2516 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2517 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2518 2519 HeapRegion* result = NULL; 2520 unsigned gc_time_stamp = get_gc_time_stamp(); 2521 2522 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2523 // Cached starting region for current worker was set 2524 // during the current pause - so it's valid. 2525 // Note: the cached starting heap region may be NULL 2526 // (when the collection set is empty). 2527 result = _worker_cset_start_region[worker_i]; 2528 assert(result == NULL || result->in_collection_set(), "sanity"); 2529 return result; 2530 } 2531 2532 // The cached entry was not valid so let's calculate 2533 // a suitable starting heap region for this worker. 2534 2535 // We want the parallel threads to start their collection 2536 // set iteration at different collection set regions to 2537 // avoid contention. 2538 // If we have: 2539 // n collection set regions 2540 // p threads 2541 // Then thread t will start at region floor ((t * n) / p) 2542 2543 result = g1_policy()->collection_set(); 2544 uint cs_size = g1_policy()->cset_region_length(); 2545 uint active_workers = workers()->active_workers(); 2546 assert(UseDynamicNumberOfGCThreads || 2547 active_workers == workers()->total_workers(), 2548 "Unless dynamic should use total workers"); 2549 2550 uint end_ind = (cs_size * worker_i) / active_workers; 2551 uint start_ind = 0; 2552 2553 if (worker_i > 0 && 2554 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2555 // Previous workers starting region is valid 2556 // so let's iterate from there 2557 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2558 result = _worker_cset_start_region[worker_i - 1]; 2559 } 2560 2561 for (uint i = start_ind; i < end_ind; i++) { 2562 result = result->next_in_collection_set(); 2563 } 2564 2565 // Note: the calculated starting heap region may be NULL 2566 // (when the collection set is empty). 2567 assert(result == NULL || result->in_collection_set(), "sanity"); 2568 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2569 "should be updated only once per pause"); 2570 _worker_cset_start_region[worker_i] = result; 2571 OrderAccess::storestore(); 2572 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2573 return result; 2574 } 2575 2576 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2577 HeapRegion* r = g1_policy()->collection_set(); 2578 while (r != NULL) { 2579 HeapRegion* next = r->next_in_collection_set(); 2580 if (cl->doHeapRegion(r)) { 2581 cl->incomplete(); 2582 return; 2583 } 2584 r = next; 2585 } 2586 } 2587 2588 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2589 HeapRegionClosure *cl) { 2590 if (r == NULL) { 2591 // The CSet is empty so there's nothing to do. 2592 return; 2593 } 2594 2595 assert(r->in_collection_set(), 2596 "Start region must be a member of the collection set."); 2597 HeapRegion* cur = r; 2598 while (cur != NULL) { 2599 HeapRegion* next = cur->next_in_collection_set(); 2600 if (cl->doHeapRegion(cur) && false) { 2601 cl->incomplete(); 2602 return; 2603 } 2604 cur = next; 2605 } 2606 cur = g1_policy()->collection_set(); 2607 while (cur != r) { 2608 HeapRegion* next = cur->next_in_collection_set(); 2609 if (cl->doHeapRegion(cur) && false) { 2610 cl->incomplete(); 2611 return; 2612 } 2613 cur = next; 2614 } 2615 } 2616 2617 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2618 HeapRegion* result = _hrm.next_region_in_heap(from); 2619 while (result != NULL && result->is_humongous()) { 2620 result = _hrm.next_region_in_heap(result); 2621 } 2622 return result; 2623 } 2624 2625 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2626 HeapRegion* hr = heap_region_containing(addr); 2627 return hr->block_start(addr); 2628 } 2629 2630 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2631 HeapRegion* hr = heap_region_containing(addr); 2632 return hr->block_size(addr); 2633 } 2634 2635 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2636 HeapRegion* hr = heap_region_containing(addr); 2637 return hr->block_is_obj(addr); 2638 } 2639 2640 bool G1CollectedHeap::supports_tlab_allocation() const { 2641 return true; 2642 } 2643 2644 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2645 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2646 } 2647 2648 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2649 return young_list()->eden_used_bytes(); 2650 } 2651 2652 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2653 // must be smaller than the humongous object limit. 2654 size_t G1CollectedHeap::max_tlab_size() const { 2655 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 2656 } 2657 2658 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2659 // Return the remaining space in the cur alloc region, but not less than 2660 // the min TLAB size. 2661 2662 // Also, this value can be at most the humongous object threshold, 2663 // since we can't allow tlabs to grow big enough to accommodate 2664 // humongous objects. 2665 2666 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get(); 2667 size_t max_tlab = max_tlab_size() * wordSize; 2668 if (hr == NULL) { 2669 return max_tlab; 2670 } else { 2671 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 2672 } 2673 } 2674 2675 size_t G1CollectedHeap::max_capacity() const { 2676 return _hrm.reserved().byte_size(); 2677 } 2678 2679 jlong G1CollectedHeap::millis_since_last_gc() { 2680 // assert(false, "NYI"); 2681 return 0; 2682 } 2683 2684 void G1CollectedHeap::prepare_for_verify() { 2685 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2686 ensure_parsability(false); 2687 } 2688 g1_rem_set()->prepare_for_verify(); 2689 } 2690 2691 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 2692 VerifyOption vo) { 2693 switch (vo) { 2694 case VerifyOption_G1UsePrevMarking: 2695 return hr->obj_allocated_since_prev_marking(obj); 2696 case VerifyOption_G1UseNextMarking: 2697 return hr->obj_allocated_since_next_marking(obj); 2698 case VerifyOption_G1UseMarkWord: 2699 return false; 2700 default: 2701 ShouldNotReachHere(); 2702 } 2703 return false; // keep some compilers happy 2704 } 2705 2706 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 2707 switch (vo) { 2708 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 2709 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 2710 case VerifyOption_G1UseMarkWord: return NULL; 2711 default: ShouldNotReachHere(); 2712 } 2713 return NULL; // keep some compilers happy 2714 } 2715 2716 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 2717 switch (vo) { 2718 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 2719 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 2720 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 2721 default: ShouldNotReachHere(); 2722 } 2723 return false; // keep some compilers happy 2724 } 2725 2726 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 2727 switch (vo) { 2728 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 2729 case VerifyOption_G1UseNextMarking: return "NTAMS"; 2730 case VerifyOption_G1UseMarkWord: return "NONE"; 2731 default: ShouldNotReachHere(); 2732 } 2733 return NULL; // keep some compilers happy 2734 } 2735 2736 class VerifyRootsClosure: public OopClosure { 2737 private: 2738 G1CollectedHeap* _g1h; 2739 VerifyOption _vo; 2740 bool _failures; 2741 public: 2742 // _vo == UsePrevMarking -> use "prev" marking information, 2743 // _vo == UseNextMarking -> use "next" marking information, 2744 // _vo == UseMarkWord -> use mark word from object header. 2745 VerifyRootsClosure(VerifyOption vo) : 2746 _g1h(G1CollectedHeap::heap()), 2747 _vo(vo), 2748 _failures(false) { } 2749 2750 bool failures() { return _failures; } 2751 2752 template <class T> void do_oop_nv(T* p) { 2753 T heap_oop = oopDesc::load_heap_oop(p); 2754 if (!oopDesc::is_null(heap_oop)) { 2755 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2756 if (_g1h->is_obj_dead_cond(obj, _vo)) { 2757 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 2758 "points to dead obj "PTR_FORMAT, p, (void*) obj); 2759 if (_vo == VerifyOption_G1UseMarkWord) { 2760 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 2761 } 2762 obj->print_on(gclog_or_tty); 2763 _failures = true; 2764 } 2765 } 2766 } 2767 2768 void do_oop(oop* p) { do_oop_nv(p); } 2769 void do_oop(narrowOop* p) { do_oop_nv(p); } 2770 }; 2771 2772 class G1VerifyCodeRootOopClosure: public OopClosure { 2773 G1CollectedHeap* _g1h; 2774 OopClosure* _root_cl; 2775 nmethod* _nm; 2776 VerifyOption _vo; 2777 bool _failures; 2778 2779 template <class T> void do_oop_work(T* p) { 2780 // First verify that this root is live 2781 _root_cl->do_oop(p); 2782 2783 if (!G1VerifyHeapRegionCodeRoots) { 2784 // We're not verifying the code roots attached to heap region. 2785 return; 2786 } 2787 2788 // Don't check the code roots during marking verification in a full GC 2789 if (_vo == VerifyOption_G1UseMarkWord) { 2790 return; 2791 } 2792 2793 // Now verify that the current nmethod (which contains p) is 2794 // in the code root list of the heap region containing the 2795 // object referenced by p. 2796 2797 T heap_oop = oopDesc::load_heap_oop(p); 2798 if (!oopDesc::is_null(heap_oop)) { 2799 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2800 2801 // Now fetch the region containing the object 2802 HeapRegion* hr = _g1h->heap_region_containing(obj); 2803 HeapRegionRemSet* hrrs = hr->rem_set(); 2804 // Verify that the strong code root list for this region 2805 // contains the nmethod 2806 if (!hrrs->strong_code_roots_list_contains(_nm)) { 2807 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " 2808 "from nmethod "PTR_FORMAT" not in strong " 2809 "code roots for region ["PTR_FORMAT","PTR_FORMAT")", 2810 p, _nm, hr->bottom(), hr->end()); 2811 _failures = true; 2812 } 2813 } 2814 } 2815 2816 public: 2817 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 2818 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 2819 2820 void do_oop(oop* p) { do_oop_work(p); } 2821 void do_oop(narrowOop* p) { do_oop_work(p); } 2822 2823 void set_nmethod(nmethod* nm) { _nm = nm; } 2824 bool failures() { return _failures; } 2825 }; 2826 2827 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 2828 G1VerifyCodeRootOopClosure* _oop_cl; 2829 2830 public: 2831 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 2832 _oop_cl(oop_cl) {} 2833 2834 void do_code_blob(CodeBlob* cb) { 2835 nmethod* nm = cb->as_nmethod_or_null(); 2836 if (nm != NULL) { 2837 _oop_cl->set_nmethod(nm); 2838 nm->oops_do(_oop_cl); 2839 } 2840 } 2841 }; 2842 2843 class YoungRefCounterClosure : public OopClosure { 2844 G1CollectedHeap* _g1h; 2845 int _count; 2846 public: 2847 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 2848 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 2849 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 2850 2851 int count() { return _count; } 2852 void reset_count() { _count = 0; }; 2853 }; 2854 2855 class VerifyKlassClosure: public KlassClosure { 2856 YoungRefCounterClosure _young_ref_counter_closure; 2857 OopClosure *_oop_closure; 2858 public: 2859 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 2860 void do_klass(Klass* k) { 2861 k->oops_do(_oop_closure); 2862 2863 _young_ref_counter_closure.reset_count(); 2864 k->oops_do(&_young_ref_counter_closure); 2865 if (_young_ref_counter_closure.count() > 0) { 2866 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k)); 2867 } 2868 } 2869 }; 2870 2871 class VerifyLivenessOopClosure: public OopClosure { 2872 G1CollectedHeap* _g1h; 2873 VerifyOption _vo; 2874 public: 2875 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 2876 _g1h(g1h), _vo(vo) 2877 { } 2878 void do_oop(narrowOop *p) { do_oop_work(p); } 2879 void do_oop( oop *p) { do_oop_work(p); } 2880 2881 template <class T> void do_oop_work(T *p) { 2882 oop obj = oopDesc::load_decode_heap_oop(p); 2883 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 2884 "Dead object referenced by a not dead object"); 2885 } 2886 }; 2887 2888 class VerifyObjsInRegionClosure: public ObjectClosure { 2889 private: 2890 G1CollectedHeap* _g1h; 2891 size_t _live_bytes; 2892 HeapRegion *_hr; 2893 VerifyOption _vo; 2894 public: 2895 // _vo == UsePrevMarking -> use "prev" marking information, 2896 // _vo == UseNextMarking -> use "next" marking information, 2897 // _vo == UseMarkWord -> use mark word from object header. 2898 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 2899 : _live_bytes(0), _hr(hr), _vo(vo) { 2900 _g1h = G1CollectedHeap::heap(); 2901 } 2902 void do_object(oop o) { 2903 VerifyLivenessOopClosure isLive(_g1h, _vo); 2904 assert(o != NULL, "Huh?"); 2905 if (!_g1h->is_obj_dead_cond(o, _vo)) { 2906 // If the object is alive according to the mark word, 2907 // then verify that the marking information agrees. 2908 // Note we can't verify the contra-positive of the 2909 // above: if the object is dead (according to the mark 2910 // word), it may not be marked, or may have been marked 2911 // but has since became dead, or may have been allocated 2912 // since the last marking. 2913 if (_vo == VerifyOption_G1UseMarkWord) { 2914 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 2915 } 2916 2917 o->oop_iterate_no_header(&isLive); 2918 if (!_hr->obj_allocated_since_prev_marking(o)) { 2919 size_t obj_size = o->size(); // Make sure we don't overflow 2920 _live_bytes += (obj_size * HeapWordSize); 2921 } 2922 } 2923 } 2924 size_t live_bytes() { return _live_bytes; } 2925 }; 2926 2927 class PrintObjsInRegionClosure : public ObjectClosure { 2928 HeapRegion *_hr; 2929 G1CollectedHeap *_g1; 2930 public: 2931 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 2932 _g1 = G1CollectedHeap::heap(); 2933 }; 2934 2935 void do_object(oop o) { 2936 if (o != NULL) { 2937 HeapWord *start = (HeapWord *) o; 2938 size_t word_sz = o->size(); 2939 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 2940 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 2941 (void*) o, word_sz, 2942 _g1->isMarkedPrev(o), 2943 _g1->isMarkedNext(o), 2944 _hr->obj_allocated_since_prev_marking(o)); 2945 HeapWord *end = start + word_sz; 2946 HeapWord *cur; 2947 int *val; 2948 for (cur = start; cur < end; cur++) { 2949 val = (int *) cur; 2950 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val); 2951 } 2952 } 2953 } 2954 }; 2955 2956 class VerifyRegionClosure: public HeapRegionClosure { 2957 private: 2958 bool _par; 2959 VerifyOption _vo; 2960 bool _failures; 2961 public: 2962 // _vo == UsePrevMarking -> use "prev" marking information, 2963 // _vo == UseNextMarking -> use "next" marking information, 2964 // _vo == UseMarkWord -> use mark word from object header. 2965 VerifyRegionClosure(bool par, VerifyOption vo) 2966 : _par(par), 2967 _vo(vo), 2968 _failures(false) {} 2969 2970 bool failures() { 2971 return _failures; 2972 } 2973 2974 bool doHeapRegion(HeapRegion* r) { 2975 if (!r->is_continues_humongous()) { 2976 bool failures = false; 2977 r->verify(_vo, &failures); 2978 if (failures) { 2979 _failures = true; 2980 } else { 2981 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 2982 r->object_iterate(¬_dead_yet_cl); 2983 if (_vo != VerifyOption_G1UseNextMarking) { 2984 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 2985 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 2986 "max_live_bytes "SIZE_FORMAT" " 2987 "< calculated "SIZE_FORMAT, 2988 r->bottom(), r->end(), 2989 r->max_live_bytes(), 2990 not_dead_yet_cl.live_bytes()); 2991 _failures = true; 2992 } 2993 } else { 2994 // When vo == UseNextMarking we cannot currently do a sanity 2995 // check on the live bytes as the calculation has not been 2996 // finalized yet. 2997 } 2998 } 2999 } 3000 return false; // stop the region iteration if we hit a failure 3001 } 3002 }; 3003 3004 // This is the task used for parallel verification of the heap regions 3005 3006 class G1ParVerifyTask: public AbstractGangTask { 3007 private: 3008 G1CollectedHeap* _g1h; 3009 VerifyOption _vo; 3010 bool _failures; 3011 HeapRegionClaimer _hrclaimer; 3012 3013 public: 3014 // _vo == UsePrevMarking -> use "prev" marking information, 3015 // _vo == UseNextMarking -> use "next" marking information, 3016 // _vo == UseMarkWord -> use mark word from object header. 3017 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3018 AbstractGangTask("Parallel verify task"), 3019 _g1h(g1h), 3020 _vo(vo), 3021 _failures(false), 3022 _hrclaimer(g1h->workers()->active_workers()) {} 3023 3024 bool failures() { 3025 return _failures; 3026 } 3027 3028 void work(uint worker_id) { 3029 HandleMark hm; 3030 VerifyRegionClosure blk(true, _vo); 3031 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer); 3032 if (blk.failures()) { 3033 _failures = true; 3034 } 3035 } 3036 }; 3037 3038 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3039 if (SafepointSynchronize::is_at_safepoint()) { 3040 assert(Thread::current()->is_VM_thread(), 3041 "Expected to be executed serially by the VM thread at this point"); 3042 3043 if (!silent) { gclog_or_tty->print("Roots "); } 3044 VerifyRootsClosure rootsCl(vo); 3045 VerifyKlassClosure klassCl(this, &rootsCl); 3046 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3047 3048 // We apply the relevant closures to all the oops in the 3049 // system dictionary, class loader data graph, the string table 3050 // and the nmethods in the code cache. 3051 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3052 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3053 3054 { 3055 G1RootProcessor root_processor(this); 3056 root_processor.process_all_roots(&rootsCl, 3057 &cldCl, 3058 &blobsCl); 3059 } 3060 3061 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3062 3063 if (vo != VerifyOption_G1UseMarkWord) { 3064 // If we're verifying during a full GC then the region sets 3065 // will have been torn down at the start of the GC. Therefore 3066 // verifying the region sets will fail. So we only verify 3067 // the region sets when not in a full GC. 3068 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3069 verify_region_sets(); 3070 } 3071 3072 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3073 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3074 3075 G1ParVerifyTask task(this, vo); 3076 assert(UseDynamicNumberOfGCThreads || 3077 workers()->active_workers() == workers()->total_workers(), 3078 "If not dynamic should be using all the workers"); 3079 int n_workers = workers()->active_workers(); 3080 set_par_threads(n_workers); 3081 workers()->run_task(&task); 3082 set_par_threads(0); 3083 if (task.failures()) { 3084 failures = true; 3085 } 3086 3087 } else { 3088 VerifyRegionClosure blk(false, vo); 3089 heap_region_iterate(&blk); 3090 if (blk.failures()) { 3091 failures = true; 3092 } 3093 } 3094 3095 if (G1StringDedup::is_enabled()) { 3096 if (!silent) gclog_or_tty->print("StrDedup "); 3097 G1StringDedup::verify(); 3098 } 3099 3100 if (failures) { 3101 gclog_or_tty->print_cr("Heap:"); 3102 // It helps to have the per-region information in the output to 3103 // help us track down what went wrong. This is why we call 3104 // print_extended_on() instead of print_on(). 3105 print_extended_on(gclog_or_tty); 3106 gclog_or_tty->cr(); 3107 #ifndef PRODUCT 3108 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 3109 concurrent_mark()->print_reachable("at-verification-failure", 3110 vo, false /* all */); 3111 } 3112 #endif 3113 gclog_or_tty->flush(); 3114 } 3115 guarantee(!failures, "there should not have been any failures"); 3116 } else { 3117 if (!silent) { 3118 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3119 if (G1StringDedup::is_enabled()) { 3120 gclog_or_tty->print(", StrDedup"); 3121 } 3122 gclog_or_tty->print(") "); 3123 } 3124 } 3125 } 3126 3127 void G1CollectedHeap::verify(bool silent) { 3128 verify(silent, VerifyOption_G1UsePrevMarking); 3129 } 3130 3131 double G1CollectedHeap::verify(bool guard, const char* msg) { 3132 double verify_time_ms = 0.0; 3133 3134 if (guard && total_collections() >= VerifyGCStartAt) { 3135 double verify_start = os::elapsedTime(); 3136 HandleMark hm; // Discard invalid handles created during verification 3137 prepare_for_verify(); 3138 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3139 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3140 } 3141 3142 return verify_time_ms; 3143 } 3144 3145 void G1CollectedHeap::verify_before_gc() { 3146 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3147 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3148 } 3149 3150 void G1CollectedHeap::verify_after_gc() { 3151 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3152 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3153 } 3154 3155 class PrintRegionClosure: public HeapRegionClosure { 3156 outputStream* _st; 3157 public: 3158 PrintRegionClosure(outputStream* st) : _st(st) {} 3159 bool doHeapRegion(HeapRegion* r) { 3160 r->print_on(_st); 3161 return false; 3162 } 3163 }; 3164 3165 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3166 const HeapRegion* hr, 3167 const VerifyOption vo) const { 3168 switch (vo) { 3169 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3170 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3171 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3172 default: ShouldNotReachHere(); 3173 } 3174 return false; // keep some compilers happy 3175 } 3176 3177 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3178 const VerifyOption vo) const { 3179 switch (vo) { 3180 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3181 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3182 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3183 default: ShouldNotReachHere(); 3184 } 3185 return false; // keep some compilers happy 3186 } 3187 3188 void G1CollectedHeap::print_on(outputStream* st) const { 3189 st->print(" %-20s", "garbage-first heap"); 3190 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3191 capacity()/K, used_unlocked()/K); 3192 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3193 _hrm.reserved().start(), 3194 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords, 3195 _hrm.reserved().end()); 3196 st->cr(); 3197 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3198 uint young_regions = _young_list->length(); 3199 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3200 (size_t) young_regions * HeapRegion::GrainBytes / K); 3201 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3202 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3203 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3204 st->cr(); 3205 MetaspaceAux::print_on(st); 3206 } 3207 3208 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3209 print_on(st); 3210 3211 // Print the per-region information. 3212 st->cr(); 3213 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3214 "HS=humongous(starts), HC=humongous(continues), " 3215 "CS=collection set, F=free, TS=gc time stamp, " 3216 "PTAMS=previous top-at-mark-start, " 3217 "NTAMS=next top-at-mark-start)"); 3218 PrintRegionClosure blk(st); 3219 heap_region_iterate(&blk); 3220 } 3221 3222 void G1CollectedHeap::print_on_error(outputStream* st) const { 3223 this->CollectedHeap::print_on_error(st); 3224 3225 if (_cm != NULL) { 3226 st->cr(); 3227 _cm->print_on_error(st); 3228 } 3229 } 3230 3231 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3232 workers()->print_worker_threads_on(st); 3233 _cmThread->print_on(st); 3234 st->cr(); 3235 _cm->print_worker_threads_on(st); 3236 _cg1r->print_worker_threads_on(st); 3237 if (G1StringDedup::is_enabled()) { 3238 G1StringDedup::print_worker_threads_on(st); 3239 } 3240 } 3241 3242 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3243 workers()->threads_do(tc); 3244 tc->do_thread(_cmThread); 3245 _cg1r->threads_do(tc); 3246 if (G1StringDedup::is_enabled()) { 3247 G1StringDedup::threads_do(tc); 3248 } 3249 } 3250 3251 void G1CollectedHeap::print_tracing_info() const { 3252 // We'll overload this to mean "trace GC pause statistics." 3253 if (TraceYoungGenTime || TraceOldGenTime) { 3254 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3255 // to that. 3256 g1_policy()->print_tracing_info(); 3257 } 3258 if (G1SummarizeRSetStats) { 3259 g1_rem_set()->print_summary_info(); 3260 } 3261 if (G1SummarizeConcMark) { 3262 concurrent_mark()->print_summary_info(); 3263 } 3264 g1_policy()->print_yg_surv_rate_info(); 3265 } 3266 3267 #ifndef PRODUCT 3268 // Helpful for debugging RSet issues. 3269 3270 class PrintRSetsClosure : public HeapRegionClosure { 3271 private: 3272 const char* _msg; 3273 size_t _occupied_sum; 3274 3275 public: 3276 bool doHeapRegion(HeapRegion* r) { 3277 HeapRegionRemSet* hrrs = r->rem_set(); 3278 size_t occupied = hrrs->occupied(); 3279 _occupied_sum += occupied; 3280 3281 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3282 HR_FORMAT_PARAMS(r)); 3283 if (occupied == 0) { 3284 gclog_or_tty->print_cr(" RSet is empty"); 3285 } else { 3286 hrrs->print(); 3287 } 3288 gclog_or_tty->print_cr("----------"); 3289 return false; 3290 } 3291 3292 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3293 gclog_or_tty->cr(); 3294 gclog_or_tty->print_cr("========================================"); 3295 gclog_or_tty->print_cr("%s", msg); 3296 gclog_or_tty->cr(); 3297 } 3298 3299 ~PrintRSetsClosure() { 3300 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3301 gclog_or_tty->print_cr("========================================"); 3302 gclog_or_tty->cr(); 3303 } 3304 }; 3305 3306 void G1CollectedHeap::print_cset_rsets() { 3307 PrintRSetsClosure cl("Printing CSet RSets"); 3308 collection_set_iterate(&cl); 3309 } 3310 3311 void G1CollectedHeap::print_all_rsets() { 3312 PrintRSetsClosure cl("Printing All RSets");; 3313 heap_region_iterate(&cl); 3314 } 3315 #endif // PRODUCT 3316 3317 G1CollectedHeap* G1CollectedHeap::heap() { 3318 return _g1h; 3319 } 3320 3321 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3322 // always_do_update_barrier = false; 3323 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3324 // Fill TLAB's and such 3325 accumulate_statistics_all_tlabs(); 3326 ensure_parsability(true); 3327 3328 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3329 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3330 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3331 } 3332 } 3333 3334 void G1CollectedHeap::gc_epilogue(bool full) { 3335 3336 if (G1SummarizeRSetStats && 3337 (G1SummarizeRSetStatsPeriod > 0) && 3338 // we are at the end of the GC. Total collections has already been increased. 3339 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3340 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3341 } 3342 3343 // FIXME: what is this about? 3344 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3345 // is set. 3346 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3347 "derived pointer present")); 3348 // always_do_update_barrier = true; 3349 3350 resize_all_tlabs(); 3351 allocation_context_stats().update(full); 3352 3353 // We have just completed a GC. Update the soft reference 3354 // policy with the new heap occupancy 3355 Universe::update_heap_info_at_gc(); 3356 } 3357 3358 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3359 uint gc_count_before, 3360 bool* succeeded, 3361 GCCause::Cause gc_cause) { 3362 assert_heap_not_locked_and_not_at_safepoint(); 3363 g1_policy()->record_stop_world_start(); 3364 VM_G1IncCollectionPause op(gc_count_before, 3365 word_size, 3366 false, /* should_initiate_conc_mark */ 3367 g1_policy()->max_pause_time_ms(), 3368 gc_cause); 3369 3370 op.set_allocation_context(AllocationContext::current()); 3371 VMThread::execute(&op); 3372 3373 HeapWord* result = op.result(); 3374 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3375 assert(result == NULL || ret_succeeded, 3376 "the result should be NULL if the VM did not succeed"); 3377 *succeeded = ret_succeeded; 3378 3379 assert_heap_not_locked(); 3380 return result; 3381 } 3382 3383 void 3384 G1CollectedHeap::doConcurrentMark() { 3385 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3386 if (!_cmThread->in_progress()) { 3387 _cmThread->set_started(); 3388 CGC_lock->notify(); 3389 } 3390 } 3391 3392 size_t G1CollectedHeap::pending_card_num() { 3393 size_t extra_cards = 0; 3394 JavaThread *curr = Threads::first(); 3395 while (curr != NULL) { 3396 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3397 extra_cards += dcq.size(); 3398 curr = curr->next(); 3399 } 3400 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3401 size_t buffer_size = dcqs.buffer_size(); 3402 size_t buffer_num = dcqs.completed_buffers_num(); 3403 3404 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3405 // in bytes - not the number of 'entries'. We need to convert 3406 // into a number of cards. 3407 return (buffer_size * buffer_num + extra_cards) / oopSize; 3408 } 3409 3410 size_t G1CollectedHeap::cards_scanned() { 3411 return g1_rem_set()->cardsScanned(); 3412 } 3413 3414 bool G1CollectedHeap::humongous_region_is_always_live(uint index) { 3415 HeapRegion* region = region_at(index); 3416 assert(region->is_starts_humongous(), "Must start a humongous object"); 3417 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty(); 3418 } 3419 3420 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3421 private: 3422 size_t _total_humongous; 3423 size_t _candidate_humongous; 3424 3425 DirtyCardQueue _dcq; 3426 3427 bool humongous_region_is_candidate(uint index) { 3428 HeapRegion* region = G1CollectedHeap::heap()->region_at(index); 3429 assert(region->is_starts_humongous(), "Must start a humongous object"); 3430 HeapRegionRemSet* const rset = region->rem_set(); 3431 bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs; 3432 return !oop(region->bottom())->is_objArray() && 3433 ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) || 3434 (!allow_stale_refs && rset->is_empty())); 3435 } 3436 3437 public: 3438 RegisterHumongousWithInCSetFastTestClosure() 3439 : _total_humongous(0), 3440 _candidate_humongous(0), 3441 _dcq(&JavaThread::dirty_card_queue_set()) { 3442 } 3443 3444 virtual bool doHeapRegion(HeapRegion* r) { 3445 if (!r->is_starts_humongous()) { 3446 return false; 3447 } 3448 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3449 3450 uint region_idx = r->hrm_index(); 3451 bool is_candidate = humongous_region_is_candidate(region_idx); 3452 // Is_candidate already filters out humongous object with large remembered sets. 3453 // If we have a humongous object with a few remembered sets, we simply flush these 3454 // remembered set entries into the DCQS. That will result in automatic 3455 // re-evaluation of their remembered set entries during the following evacuation 3456 // phase. 3457 if (is_candidate) { 3458 if (!r->rem_set()->is_empty()) { 3459 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 3460 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 3461 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 3462 HeapRegionRemSetIterator hrrs(r->rem_set()); 3463 size_t card_index; 3464 while (hrrs.has_next(card_index)) { 3465 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 3466 // The remembered set might contain references to already freed 3467 // regions. Filter out such entries to avoid failing card table 3468 // verification. 3469 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) { 3470 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 3471 *card_ptr = CardTableModRefBS::dirty_card_val(); 3472 _dcq.enqueue(card_ptr); 3473 } 3474 } 3475 } 3476 r->rem_set()->clear_locked(); 3477 } 3478 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 3479 g1h->register_humongous_region_with_cset(region_idx); 3480 _candidate_humongous++; 3481 } 3482 _total_humongous++; 3483 3484 return false; 3485 } 3486 3487 size_t total_humongous() const { return _total_humongous; } 3488 size_t candidate_humongous() const { return _candidate_humongous; } 3489 3490 void flush_rem_set_entries() { _dcq.flush(); } 3491 }; 3492 3493 void G1CollectedHeap::register_humongous_regions_with_cset() { 3494 if (!G1EagerReclaimHumongousObjects) { 3495 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 3496 return; 3497 } 3498 double time = os::elapsed_counter(); 3499 3500 RegisterHumongousWithInCSetFastTestClosure cl; 3501 heap_region_iterate(&cl); 3502 3503 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 3504 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 3505 cl.total_humongous(), 3506 cl.candidate_humongous()); 3507 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3508 3509 if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) { 3510 clear_humongous_is_live_table(); 3511 } 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 int n = workers()->total_workers(); 3584 for (int i = 0; i < n; ++i) { 3585 st->print("%3d ", 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 int n = workers()->total_workers(); 3595 for (int 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(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") 3610 .append(g1_policy()->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 print_heap_before_gc(); 3655 trace_heap_before_gc(_gc_tracer_stw); 3656 3657 verify_region_sets_optional(); 3658 verify_dirty_young_regions(); 3659 3660 // This call will decide whether this pause is an initial-mark 3661 // pause. If it is, during_initial_mark_pause() will return true 3662 // for the duration of this pause. 3663 g1_policy()->decide_on_conc_mark_initiation(); 3664 3665 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3666 assert(!g1_policy()->during_initial_mark_pause() || 3667 g1_policy()->gcs_are_young(), "sanity"); 3668 3669 // We also do not allow mixed GCs during marking. 3670 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3671 3672 // Record whether this pause is an initial mark. When the current 3673 // thread has completed its logging output and it's safe to signal 3674 // the CM thread, the flag's value in the policy has been reset. 3675 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3676 3677 // Inner scope for scope based logging, timers, and stats collection 3678 { 3679 EvacuationInfo evacuation_info; 3680 3681 if (g1_policy()->during_initial_mark_pause()) { 3682 // We are about to start a marking cycle, so we increment the 3683 // full collection counter. 3684 increment_old_marking_cycles_started(); 3685 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3686 } 3687 3688 _gc_tracer_stw->report_yc_type(yc_type()); 3689 3690 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3691 3692 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 3693 workers()->active_workers(), 3694 Threads::number_of_non_daemon_threads()); 3695 assert(UseDynamicNumberOfGCThreads || 3696 active_workers == workers()->total_workers(), 3697 "If not dynamic should be using all the workers"); 3698 workers()->set_active_workers(active_workers); 3699 3700 double pause_start_sec = os::elapsedTime(); 3701 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress()); 3702 log_gc_header(); 3703 3704 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3705 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3706 3707 // If the secondary_free_list is not empty, append it to the 3708 // free_list. No need to wait for the cleanup operation to finish; 3709 // the region allocation code will check the secondary_free_list 3710 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3711 // set, skip this step so that the region allocation code has to 3712 // get entries from the secondary_free_list. 3713 if (!G1StressConcRegionFreeing) { 3714 append_secondary_free_list_if_not_empty_with_lock(); 3715 } 3716 3717 assert(check_young_list_well_formed(), "young list should be well formed"); 3718 3719 // Don't dynamically change the number of GC threads this early. A value of 3720 // 0 is used to indicate serial work. When parallel work is done, 3721 // it will be set. 3722 3723 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3724 IsGCActiveMark x; 3725 3726 gc_prologue(false); 3727 increment_total_collections(false /* full gc */); 3728 increment_gc_time_stamp(); 3729 3730 verify_before_gc(); 3731 3732 check_bitmaps("GC Start"); 3733 3734 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3735 3736 // Please see comment in g1CollectedHeap.hpp and 3737 // G1CollectedHeap::ref_processing_init() to see how 3738 // reference processing currently works in G1. 3739 3740 // Enable discovery in the STW reference processor 3741 ref_processor_stw()->enable_discovery(); 3742 3743 { 3744 // We want to temporarily turn off discovery by the 3745 // CM ref processor, if necessary, and turn it back on 3746 // on again later if we do. Using a scoped 3747 // NoRefDiscovery object will do this. 3748 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3749 3750 // Forget the current alloc region (we might even choose it to be part 3751 // of the collection set!). 3752 _allocator->release_mutator_alloc_region(); 3753 3754 // We should call this after we retire the mutator alloc 3755 // region(s) so that all the ALLOC / RETIRE events are generated 3756 // before the start GC event. 3757 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3758 3759 // This timing is only used by the ergonomics to handle our pause target. 3760 // It is unclear why this should not include the full pause. We will 3761 // investigate this in CR 7178365. 3762 // 3763 // Preserving the old comment here if that helps the investigation: 3764 // 3765 // The elapsed time induced by the start time below deliberately elides 3766 // the possible verification above. 3767 double sample_start_time_sec = os::elapsedTime(); 3768 3769 #if YOUNG_LIST_VERBOSE 3770 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 3771 _young_list->print(); 3772 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3773 #endif // YOUNG_LIST_VERBOSE 3774 3775 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3776 3777 double scan_wait_start = os::elapsedTime(); 3778 // We have to wait until the CM threads finish scanning the 3779 // root regions as it's the only way to ensure that all the 3780 // objects on them have been correctly scanned before we start 3781 // moving them during the GC. 3782 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3783 double wait_time_ms = 0.0; 3784 if (waited) { 3785 double scan_wait_end = os::elapsedTime(); 3786 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3787 } 3788 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3789 3790 #if YOUNG_LIST_VERBOSE 3791 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 3792 _young_list->print(); 3793 #endif // YOUNG_LIST_VERBOSE 3794 3795 if (g1_policy()->during_initial_mark_pause()) { 3796 concurrent_mark()->checkpointRootsInitialPre(); 3797 } 3798 3799 #if YOUNG_LIST_VERBOSE 3800 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 3801 _young_list->print(); 3802 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3803 #endif // YOUNG_LIST_VERBOSE 3804 3805 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 3806 3807 register_humongous_regions_with_cset(); 3808 3809 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3810 3811 _cm->note_start_of_gc(); 3812 // We should not verify the per-thread SATB buffers given that 3813 // we have not filtered them yet (we'll do so during the 3814 // GC). We also call this after finalize_cset() to 3815 // ensure that the CSet has been finalized. 3816 _cm->verify_no_cset_oops(true /* verify_stacks */, 3817 true /* verify_enqueued_buffers */, 3818 false /* verify_thread_buffers */, 3819 true /* verify_fingers */); 3820 3821 if (_hr_printer.is_active()) { 3822 HeapRegion* hr = g1_policy()->collection_set(); 3823 while (hr != NULL) { 3824 _hr_printer.cset(hr); 3825 hr = hr->next_in_collection_set(); 3826 } 3827 } 3828 3829 #ifdef ASSERT 3830 VerifyCSetClosure cl; 3831 collection_set_iterate(&cl); 3832 #endif // ASSERT 3833 3834 setup_surviving_young_words(); 3835 3836 // Initialize the GC alloc regions. 3837 _allocator->init_gc_alloc_regions(evacuation_info); 3838 3839 // Actually do the work... 3840 evacuate_collection_set(evacuation_info); 3841 3842 // We do this to mainly verify the per-thread SATB buffers 3843 // (which have been filtered by now) since we didn't verify 3844 // them earlier. No point in re-checking the stacks / enqueued 3845 // buffers given that the CSet has not changed since last time 3846 // we checked. 3847 _cm->verify_no_cset_oops(false /* verify_stacks */, 3848 false /* verify_enqueued_buffers */, 3849 true /* verify_thread_buffers */, 3850 true /* verify_fingers */); 3851 3852 free_collection_set(g1_policy()->collection_set(), evacuation_info); 3853 3854 eagerly_reclaim_humongous_regions(); 3855 3856 g1_policy()->clear_collection_set(); 3857 3858 cleanup_surviving_young_words(); 3859 3860 // Start a new incremental collection set for the next pause. 3861 g1_policy()->start_incremental_cset_building(); 3862 3863 clear_cset_fast_test(); 3864 3865 _young_list->reset_sampled_info(); 3866 3867 // Don't check the whole heap at this point as the 3868 // GC alloc regions from this pause have been tagged 3869 // as survivors and moved on to the survivor list. 3870 // Survivor regions will fail the !is_young() check. 3871 assert(check_young_list_empty(false /* check_heap */), 3872 "young list should be empty"); 3873 3874 #if YOUNG_LIST_VERBOSE 3875 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 3876 _young_list->print(); 3877 #endif // YOUNG_LIST_VERBOSE 3878 3879 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 3880 _young_list->first_survivor_region(), 3881 _young_list->last_survivor_region()); 3882 3883 _young_list->reset_auxilary_lists(); 3884 3885 if (evacuation_failed()) { 3886 _allocator->set_used(recalculate_used()); 3887 uint n_queues = MAX2((int)ParallelGCThreads, 1); 3888 for (uint i = 0; i < n_queues; i++) { 3889 if (_evacuation_failed_info_array[i].has_failed()) { 3890 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3891 } 3892 } 3893 } else { 3894 // The "used" of the the collection set have already been subtracted 3895 // when they were freed. Add in the bytes evacuated. 3896 _allocator->increase_used(g1_policy()->bytes_copied_during_gc()); 3897 } 3898 3899 if (g1_policy()->during_initial_mark_pause()) { 3900 // We have to do this before we notify the CM threads that 3901 // they can start working to make sure that all the 3902 // appropriate initialization is done on the CM object. 3903 concurrent_mark()->checkpointRootsInitialPost(); 3904 set_marking_started(); 3905 // Note that we don't actually trigger the CM thread at 3906 // this point. We do that later when we're sure that 3907 // the current thread has completed its logging output. 3908 } 3909 3910 allocate_dummy_regions(); 3911 3912 #if YOUNG_LIST_VERBOSE 3913 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 3914 _young_list->print(); 3915 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3916 #endif // YOUNG_LIST_VERBOSE 3917 3918 _allocator->init_mutator_alloc_region(); 3919 3920 { 3921 size_t expand_bytes = g1_policy()->expansion_amount(); 3922 if (expand_bytes > 0) { 3923 size_t bytes_before = capacity(); 3924 // No need for an ergo verbose message here, 3925 // expansion_amount() does this when it returns a value > 0. 3926 if (!expand(expand_bytes)) { 3927 // We failed to expand the heap. Cannot do anything about it. 3928 } 3929 } 3930 } 3931 3932 // We redo the verification but now wrt to the new CSet which 3933 // has just got initialized after the previous CSet was freed. 3934 _cm->verify_no_cset_oops(true /* verify_stacks */, 3935 true /* verify_enqueued_buffers */, 3936 true /* verify_thread_buffers */, 3937 true /* verify_fingers */); 3938 _cm->note_end_of_gc(); 3939 3940 // This timing is only used by the ergonomics to handle our pause target. 3941 // It is unclear why this should not include the full pause. We will 3942 // investigate this in CR 7178365. 3943 double sample_end_time_sec = os::elapsedTime(); 3944 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3945 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 3946 3947 MemoryService::track_memory_usage(); 3948 3949 // In prepare_for_verify() below we'll need to scan the deferred 3950 // update buffers to bring the RSets up-to-date if 3951 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 3952 // the update buffers we'll probably need to scan cards on the 3953 // regions we just allocated to (i.e., the GC alloc 3954 // regions). However, during the last GC we called 3955 // set_saved_mark() on all the GC alloc regions, so card 3956 // scanning might skip the [saved_mark_word()...top()] area of 3957 // those regions (i.e., the area we allocated objects into 3958 // during the last GC). But it shouldn't. Given that 3959 // saved_mark_word() is conditional on whether the GC time stamp 3960 // on the region is current or not, by incrementing the GC time 3961 // stamp here we invalidate all the GC time stamps on all the 3962 // regions and saved_mark_word() will simply return top() for 3963 // all the regions. This is a nicer way of ensuring this rather 3964 // than iterating over the regions and fixing them. In fact, the 3965 // GC time stamp increment here also ensures that 3966 // saved_mark_word() will return top() between pauses, i.e., 3967 // during concurrent refinement. So we don't need the 3968 // is_gc_active() check to decided which top to use when 3969 // scanning cards (see CR 7039627). 3970 increment_gc_time_stamp(); 3971 3972 verify_after_gc(); 3973 check_bitmaps("GC End"); 3974 3975 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 3976 ref_processor_stw()->verify_no_references_recorded(); 3977 3978 // CM reference discovery will be re-enabled if necessary. 3979 } 3980 3981 // We should do this after we potentially expand the heap so 3982 // that all the COMMIT events are generated before the end GC 3983 // event, and after we retire the GC alloc regions so that all 3984 // RETIRE events are generated before the end GC event. 3985 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 3986 3987 #ifdef TRACESPINNING 3988 ParallelTaskTerminator::print_termination_counts(); 3989 #endif 3990 3991 gc_epilogue(false); 3992 } 3993 3994 // Print the remainder of the GC log output. 3995 log_gc_footer(os::elapsedTime() - pause_start_sec); 3996 3997 // It is not yet to safe to tell the concurrent mark to 3998 // start as we have some optional output below. We don't want the 3999 // output from the concurrent mark thread interfering with this 4000 // logging output either. 4001 4002 _hrm.verify_optional(); 4003 verify_region_sets_optional(); 4004 4005 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats()); 4006 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4007 4008 print_heap_after_gc(); 4009 trace_heap_after_gc(_gc_tracer_stw); 4010 4011 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4012 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4013 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4014 // before any GC notifications are raised. 4015 g1mm()->update_sizes(); 4016 4017 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4018 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4019 _gc_timer_stw->register_gc_end(); 4020 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4021 } 4022 // It should now be safe to tell the concurrent mark thread to start 4023 // without its logging output interfering with the logging output 4024 // that came from the pause. 4025 4026 if (should_start_conc_mark) { 4027 // CAUTION: after the doConcurrentMark() call below, 4028 // the concurrent marking thread(s) could be running 4029 // concurrently with us. Make sure that anything after 4030 // this point does not assume that we are the only GC thread 4031 // running. Note: of course, the actual marking work will 4032 // not start until the safepoint itself is released in 4033 // SuspendibleThreadSet::desynchronize(). 4034 doConcurrentMark(); 4035 } 4036 4037 return true; 4038 } 4039 4040 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4041 _drain_in_progress = false; 4042 set_evac_failure_closure(cl); 4043 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4044 } 4045 4046 void G1CollectedHeap::finalize_for_evac_failure() { 4047 assert(_evac_failure_scan_stack != NULL && 4048 _evac_failure_scan_stack->length() == 0, 4049 "Postcondition"); 4050 assert(!_drain_in_progress, "Postcondition"); 4051 delete _evac_failure_scan_stack; 4052 _evac_failure_scan_stack = NULL; 4053 } 4054 4055 void G1CollectedHeap::remove_self_forwarding_pointers() { 4056 double remove_self_forwards_start = os::elapsedTime(); 4057 4058 set_par_threads(); 4059 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4060 workers()->run_task(&rsfp_task); 4061 set_par_threads(0); 4062 4063 // Now restore saved marks, if any. 4064 assert(_objs_with_preserved_marks.size() == 4065 _preserved_marks_of_objs.size(), "Both or none."); 4066 while (!_objs_with_preserved_marks.is_empty()) { 4067 oop obj = _objs_with_preserved_marks.pop(); 4068 markOop m = _preserved_marks_of_objs.pop(); 4069 obj->set_mark(m); 4070 } 4071 _objs_with_preserved_marks.clear(true); 4072 _preserved_marks_of_objs.clear(true); 4073 4074 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4075 } 4076 4077 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4078 _evac_failure_scan_stack->push(obj); 4079 } 4080 4081 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4082 assert(_evac_failure_scan_stack != NULL, "precondition"); 4083 4084 while (_evac_failure_scan_stack->length() > 0) { 4085 oop obj = _evac_failure_scan_stack->pop(); 4086 _evac_failure_closure->set_region(heap_region_containing(obj)); 4087 obj->oop_iterate_backwards(_evac_failure_closure); 4088 } 4089 } 4090 4091 oop 4092 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4093 oop old) { 4094 assert(obj_in_cs(old), 4095 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4096 (HeapWord*) old)); 4097 markOop m = old->mark(); 4098 oop forward_ptr = old->forward_to_atomic(old); 4099 if (forward_ptr == NULL) { 4100 // Forward-to-self succeeded. 4101 assert(_par_scan_state != NULL, "par scan state"); 4102 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4103 uint queue_num = _par_scan_state->queue_num(); 4104 4105 _evacuation_failed = true; 4106 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4107 if (_evac_failure_closure != cl) { 4108 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4109 assert(!_drain_in_progress, 4110 "Should only be true while someone holds the lock."); 4111 // Set the global evac-failure closure to the current thread's. 4112 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4113 set_evac_failure_closure(cl); 4114 // Now do the common part. 4115 handle_evacuation_failure_common(old, m); 4116 // Reset to NULL. 4117 set_evac_failure_closure(NULL); 4118 } else { 4119 // The lock is already held, and this is recursive. 4120 assert(_drain_in_progress, "This should only be the recursive case."); 4121 handle_evacuation_failure_common(old, m); 4122 } 4123 return old; 4124 } else { 4125 // Forward-to-self failed. Either someone else managed to allocate 4126 // space for this object (old != forward_ptr) or they beat us in 4127 // self-forwarding it (old == forward_ptr). 4128 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4129 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4130 "should not be in the CSet", 4131 (HeapWord*) old, (HeapWord*) forward_ptr)); 4132 return forward_ptr; 4133 } 4134 } 4135 4136 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4137 preserve_mark_if_necessary(old, m); 4138 4139 HeapRegion* r = heap_region_containing(old); 4140 if (!r->evacuation_failed()) { 4141 r->set_evacuation_failed(true); 4142 _hr_printer.evac_failure(r); 4143 } 4144 4145 push_on_evac_failure_scan_stack(old); 4146 4147 if (!_drain_in_progress) { 4148 // prevent recursion in copy_to_survivor_space() 4149 _drain_in_progress = true; 4150 drain_evac_failure_scan_stack(); 4151 _drain_in_progress = false; 4152 } 4153 } 4154 4155 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4156 assert(evacuation_failed(), "Oversaving!"); 4157 // We want to call the "for_promotion_failure" version only in the 4158 // case of a promotion failure. 4159 if (m->must_be_preserved_for_promotion_failure(obj)) { 4160 _objs_with_preserved_marks.push(obj); 4161 _preserved_marks_of_objs.push(m); 4162 } 4163 } 4164 4165 void G1ParCopyHelper::mark_object(oop obj) { 4166 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); 4167 4168 // We know that the object is not moving so it's safe to read its size. 4169 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4170 } 4171 4172 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4173 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4174 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4175 assert(from_obj != to_obj, "should not be self-forwarded"); 4176 4177 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); 4178 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); 4179 4180 // The object might be in the process of being copied by another 4181 // worker so we cannot trust that its to-space image is 4182 // well-formed. So we have to read its size from its from-space 4183 // image which we know should not be changing. 4184 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4185 } 4186 4187 template <class T> 4188 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4189 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4190 _scanned_klass->record_modified_oops(); 4191 } 4192 } 4193 4194 template <G1Barrier barrier, G1Mark do_mark_object> 4195 template <class T> 4196 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4197 T heap_oop = oopDesc::load_heap_oop(p); 4198 4199 if (oopDesc::is_null(heap_oop)) { 4200 return; 4201 } 4202 4203 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4204 4205 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4206 4207 const InCSetState state = _g1->in_cset_state(obj); 4208 if (state.is_in_cset()) { 4209 oop forwardee; 4210 markOop m = obj->mark(); 4211 if (m->is_marked()) { 4212 forwardee = (oop) m->decode_pointer(); 4213 } else { 4214 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m); 4215 } 4216 assert(forwardee != NULL, "forwardee should not be NULL"); 4217 oopDesc::encode_store_heap_oop(p, forwardee); 4218 if (do_mark_object != G1MarkNone && forwardee != obj) { 4219 // If the object is self-forwarded we don't need to explicitly 4220 // mark it, the evacuation failure protocol will do so. 4221 mark_forwarded_object(obj, forwardee); 4222 } 4223 4224 if (barrier == G1BarrierKlass) { 4225 do_klass_barrier(p, forwardee); 4226 } 4227 } else { 4228 if (state.is_humongous()) { 4229 _g1->set_humongous_is_live(obj); 4230 } 4231 // The object is not in collection set. If we're a root scanning 4232 // closure during an initial mark pause then attempt to mark the object. 4233 if (do_mark_object == G1MarkFromRoot) { 4234 mark_object(obj); 4235 } 4236 } 4237 4238 if (barrier == G1BarrierEvac) { 4239 _par_scan_state->update_rs(_from, p, _worker_id); 4240 } 4241 } 4242 4243 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p); 4244 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p); 4245 4246 class G1ParEvacuateFollowersClosure : public VoidClosure { 4247 protected: 4248 G1CollectedHeap* _g1h; 4249 G1ParScanThreadState* _par_scan_state; 4250 RefToScanQueueSet* _queues; 4251 ParallelTaskTerminator* _terminator; 4252 4253 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4254 RefToScanQueueSet* queues() { return _queues; } 4255 ParallelTaskTerminator* terminator() { return _terminator; } 4256 4257 public: 4258 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4259 G1ParScanThreadState* par_scan_state, 4260 RefToScanQueueSet* queues, 4261 ParallelTaskTerminator* terminator) 4262 : _g1h(g1h), _par_scan_state(par_scan_state), 4263 _queues(queues), _terminator(terminator) {} 4264 4265 void do_void(); 4266 4267 private: 4268 inline bool offer_termination(); 4269 }; 4270 4271 bool G1ParEvacuateFollowersClosure::offer_termination() { 4272 G1ParScanThreadState* const pss = par_scan_state(); 4273 pss->start_term_time(); 4274 const bool res = terminator()->offer_termination(); 4275 pss->end_term_time(); 4276 return res; 4277 } 4278 4279 void G1ParEvacuateFollowersClosure::do_void() { 4280 G1ParScanThreadState* const pss = par_scan_state(); 4281 pss->trim_queue(); 4282 do { 4283 pss->steal_and_trim_queue(queues()); 4284 } while (!offer_termination()); 4285 } 4286 4287 class G1KlassScanClosure : public KlassClosure { 4288 G1ParCopyHelper* _closure; 4289 bool _process_only_dirty; 4290 int _count; 4291 public: 4292 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4293 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4294 void do_klass(Klass* klass) { 4295 // If the klass has not been dirtied we know that there's 4296 // no references into the young gen and we can skip it. 4297 if (!_process_only_dirty || klass->has_modified_oops()) { 4298 // Clean the klass since we're going to scavenge all the metadata. 4299 klass->clear_modified_oops(); 4300 4301 // Tell the closure that this klass is the Klass to scavenge 4302 // and is the one to dirty if oops are left pointing into the young gen. 4303 _closure->set_scanned_klass(klass); 4304 4305 klass->oops_do(_closure); 4306 4307 _closure->set_scanned_klass(NULL); 4308 } 4309 _count++; 4310 } 4311 }; 4312 4313 class G1ParTask : public AbstractGangTask { 4314 protected: 4315 G1CollectedHeap* _g1h; 4316 RefToScanQueueSet *_queues; 4317 G1RootProcessor* _root_processor; 4318 ParallelTaskTerminator _terminator; 4319 uint _n_workers; 4320 4321 Mutex _stats_lock; 4322 Mutex* stats_lock() { return &_stats_lock; } 4323 4324 public: 4325 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor) 4326 : AbstractGangTask("G1 collection"), 4327 _g1h(g1h), 4328 _queues(task_queues), 4329 _root_processor(root_processor), 4330 _terminator(0, _queues), 4331 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4332 {} 4333 4334 RefToScanQueueSet* queues() { return _queues; } 4335 4336 RefToScanQueue *work_queue(int i) { 4337 return queues()->queue(i); 4338 } 4339 4340 ParallelTaskTerminator* terminator() { return &_terminator; } 4341 4342 virtual void set_for_termination(int active_workers) { 4343 _root_processor->set_num_workers(active_workers); 4344 terminator()->reset_for_reuse(active_workers); 4345 _n_workers = active_workers; 4346 } 4347 4348 // Helps out with CLD processing. 4349 // 4350 // During InitialMark we need to: 4351 // 1) Scavenge all CLDs for the young GC. 4352 // 2) Mark all objects directly reachable from strong CLDs. 4353 template <G1Mark do_mark_object> 4354 class G1CLDClosure : public CLDClosure { 4355 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure; 4356 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure; 4357 G1KlassScanClosure _klass_in_cld_closure; 4358 bool _claim; 4359 4360 public: 4361 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure, 4362 bool only_young, bool claim) 4363 : _oop_closure(oop_closure), 4364 _oop_in_klass_closure(oop_closure->g1(), 4365 oop_closure->pss(), 4366 oop_closure->rp()), 4367 _klass_in_cld_closure(&_oop_in_klass_closure, only_young), 4368 _claim(claim) { 4369 4370 } 4371 4372 void do_cld(ClassLoaderData* cld) { 4373 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim); 4374 } 4375 }; 4376 4377 void work(uint worker_id) { 4378 if (worker_id >= _n_workers) return; // no work needed this round 4379 4380 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime()); 4381 4382 { 4383 ResourceMark rm; 4384 HandleMark hm; 4385 4386 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4387 4388 G1ParScanThreadState pss(_g1h, worker_id, rp); 4389 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 4390 4391 pss.set_evac_failure_closure(&evac_failure_cl); 4392 4393 bool only_young = _g1h->g1_policy()->gcs_are_young(); 4394 4395 // Non-IM young GC. 4396 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp); 4397 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl, 4398 only_young, // Only process dirty klasses. 4399 false); // No need to claim CLDs. 4400 // IM young GC. 4401 // Strong roots closures. 4402 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp); 4403 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl, 4404 false, // Process all klasses. 4405 true); // Need to claim CLDs. 4406 // Weak roots closures. 4407 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp); 4408 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl, 4409 false, // Process all klasses. 4410 true); // Need to claim CLDs. 4411 4412 OopClosure* strong_root_cl; 4413 OopClosure* weak_root_cl; 4414 CLDClosure* strong_cld_cl; 4415 CLDClosure* weak_cld_cl; 4416 4417 bool trace_metadata = false; 4418 4419 if (_g1h->g1_policy()->during_initial_mark_pause()) { 4420 // We also need to mark copied objects. 4421 strong_root_cl = &scan_mark_root_cl; 4422 strong_cld_cl = &scan_mark_cld_cl; 4423 if (ClassUnloadingWithConcurrentMark) { 4424 weak_root_cl = &scan_mark_weak_root_cl; 4425 weak_cld_cl = &scan_mark_weak_cld_cl; 4426 trace_metadata = true; 4427 } else { 4428 weak_root_cl = &scan_mark_root_cl; 4429 weak_cld_cl = &scan_mark_cld_cl; 4430 } 4431 } else { 4432 strong_root_cl = &scan_only_root_cl; 4433 weak_root_cl = &scan_only_root_cl; 4434 strong_cld_cl = &scan_only_cld_cl; 4435 weak_cld_cl = &scan_only_cld_cl; 4436 } 4437 4438 pss.start_strong_roots(); 4439 4440 _root_processor->evacuate_roots(strong_root_cl, 4441 weak_root_cl, 4442 strong_cld_cl, 4443 weak_cld_cl, 4444 trace_metadata, 4445 worker_id); 4446 4447 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4448 _root_processor->scan_remembered_sets(&push_heap_rs_cl, 4449 weak_root_cl, 4450 worker_id); 4451 pss.end_strong_roots(); 4452 4453 { 4454 double start = os::elapsedTime(); 4455 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4456 evac.do_void(); 4457 double elapsed_sec = os::elapsedTime() - start; 4458 double term_sec = pss.term_time(); 4459 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 4460 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 4461 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts()); 4462 } 4463 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4464 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4465 4466 if (PrintTerminationStats) { 4467 MutexLocker x(stats_lock()); 4468 pss.print_termination_stats(worker_id); 4469 } 4470 4471 assert(pss.queue_is_empty(), "should be empty"); 4472 4473 // Close the inner scope so that the ResourceMark and HandleMark 4474 // destructors are executed here and are included as part of the 4475 // "GC Worker Time". 4476 } 4477 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 4478 } 4479 }; 4480 4481 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4482 private: 4483 BoolObjectClosure* _is_alive; 4484 int _initial_string_table_size; 4485 int _initial_symbol_table_size; 4486 4487 bool _process_strings; 4488 int _strings_processed; 4489 int _strings_removed; 4490 4491 bool _process_symbols; 4492 int _symbols_processed; 4493 int _symbols_removed; 4494 4495 public: 4496 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4497 AbstractGangTask("String/Symbol Unlinking"), 4498 _is_alive(is_alive), 4499 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4500 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4501 4502 _initial_string_table_size = StringTable::the_table()->table_size(); 4503 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4504 if (process_strings) { 4505 StringTable::clear_parallel_claimed_index(); 4506 } 4507 if (process_symbols) { 4508 SymbolTable::clear_parallel_claimed_index(); 4509 } 4510 } 4511 4512 ~G1StringSymbolTableUnlinkTask() { 4513 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4514 err_msg("claim value %d after unlink less than initial string table size %d", 4515 StringTable::parallel_claimed_index(), _initial_string_table_size)); 4516 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4517 err_msg("claim value %d after unlink less than initial symbol table size %d", 4518 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 4519 4520 if (G1TraceStringSymbolTableScrubbing) { 4521 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4522 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 4523 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 4524 strings_processed(), strings_removed(), 4525 symbols_processed(), symbols_removed()); 4526 } 4527 } 4528 4529 void work(uint worker_id) { 4530 int strings_processed = 0; 4531 int strings_removed = 0; 4532 int symbols_processed = 0; 4533 int symbols_removed = 0; 4534 if (_process_strings) { 4535 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4536 Atomic::add(strings_processed, &_strings_processed); 4537 Atomic::add(strings_removed, &_strings_removed); 4538 } 4539 if (_process_symbols) { 4540 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 4541 Atomic::add(symbols_processed, &_symbols_processed); 4542 Atomic::add(symbols_removed, &_symbols_removed); 4543 } 4544 } 4545 4546 size_t strings_processed() const { return (size_t)_strings_processed; } 4547 size_t strings_removed() const { return (size_t)_strings_removed; } 4548 4549 size_t symbols_processed() const { return (size_t)_symbols_processed; } 4550 size_t symbols_removed() const { return (size_t)_symbols_removed; } 4551 }; 4552 4553 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 4554 private: 4555 static Monitor* _lock; 4556 4557 BoolObjectClosure* const _is_alive; 4558 const bool _unloading_occurred; 4559 const uint _num_workers; 4560 4561 // Variables used to claim nmethods. 4562 nmethod* _first_nmethod; 4563 volatile nmethod* _claimed_nmethod; 4564 4565 // The list of nmethods that need to be processed by the second pass. 4566 volatile nmethod* _postponed_list; 4567 volatile uint _num_entered_barrier; 4568 4569 public: 4570 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 4571 _is_alive(is_alive), 4572 _unloading_occurred(unloading_occurred), 4573 _num_workers(num_workers), 4574 _first_nmethod(NULL), 4575 _claimed_nmethod(NULL), 4576 _postponed_list(NULL), 4577 _num_entered_barrier(0) 4578 { 4579 nmethod::increase_unloading_clock(); 4580 // Get first alive nmethod 4581 NMethodIterator iter = NMethodIterator(); 4582 if(iter.next_alive()) { 4583 _first_nmethod = iter.method(); 4584 } 4585 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 4586 } 4587 4588 ~G1CodeCacheUnloadingTask() { 4589 CodeCache::verify_clean_inline_caches(); 4590 4591 CodeCache::set_needs_cache_clean(false); 4592 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 4593 4594 CodeCache::verify_icholder_relocations(); 4595 } 4596 4597 private: 4598 void add_to_postponed_list(nmethod* nm) { 4599 nmethod* old; 4600 do { 4601 old = (nmethod*)_postponed_list; 4602 nm->set_unloading_next(old); 4603 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 4604 } 4605 4606 void clean_nmethod(nmethod* nm) { 4607 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 4608 4609 if (postponed) { 4610 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 4611 add_to_postponed_list(nm); 4612 } 4613 4614 // Mark that this thread has been cleaned/unloaded. 4615 // After this call, it will be safe to ask if this nmethod was unloaded or not. 4616 nm->set_unloading_clock(nmethod::global_unloading_clock()); 4617 } 4618 4619 void clean_nmethod_postponed(nmethod* nm) { 4620 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 4621 } 4622 4623 static const int MaxClaimNmethods = 16; 4624 4625 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 4626 nmethod* first; 4627 NMethodIterator last; 4628 4629 do { 4630 *num_claimed_nmethods = 0; 4631 4632 first = (nmethod*)_claimed_nmethod; 4633 last = NMethodIterator(first); 4634 4635 if (first != NULL) { 4636 4637 for (int i = 0; i < MaxClaimNmethods; i++) { 4638 if (!last.next_alive()) { 4639 break; 4640 } 4641 claimed_nmethods[i] = last.method(); 4642 (*num_claimed_nmethods)++; 4643 } 4644 } 4645 4646 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 4647 } 4648 4649 nmethod* claim_postponed_nmethod() { 4650 nmethod* claim; 4651 nmethod* next; 4652 4653 do { 4654 claim = (nmethod*)_postponed_list; 4655 if (claim == NULL) { 4656 return NULL; 4657 } 4658 4659 next = claim->unloading_next(); 4660 4661 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 4662 4663 return claim; 4664 } 4665 4666 public: 4667 // Mark that we're done with the first pass of nmethod cleaning. 4668 void barrier_mark(uint worker_id) { 4669 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4670 _num_entered_barrier++; 4671 if (_num_entered_barrier == _num_workers) { 4672 ml.notify_all(); 4673 } 4674 } 4675 4676 // See if we have to wait for the other workers to 4677 // finish their first-pass nmethod cleaning work. 4678 void barrier_wait(uint worker_id) { 4679 if (_num_entered_barrier < _num_workers) { 4680 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4681 while (_num_entered_barrier < _num_workers) { 4682 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 4683 } 4684 } 4685 } 4686 4687 // Cleaning and unloading of nmethods. Some work has to be postponed 4688 // to the second pass, when we know which nmethods survive. 4689 void work_first_pass(uint worker_id) { 4690 // The first nmethods is claimed by the first worker. 4691 if (worker_id == 0 && _first_nmethod != NULL) { 4692 clean_nmethod(_first_nmethod); 4693 _first_nmethod = NULL; 4694 } 4695 4696 int num_claimed_nmethods; 4697 nmethod* claimed_nmethods[MaxClaimNmethods]; 4698 4699 while (true) { 4700 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 4701 4702 if (num_claimed_nmethods == 0) { 4703 break; 4704 } 4705 4706 for (int i = 0; i < num_claimed_nmethods; i++) { 4707 clean_nmethod(claimed_nmethods[i]); 4708 } 4709 } 4710 } 4711 4712 void work_second_pass(uint worker_id) { 4713 nmethod* nm; 4714 // Take care of postponed nmethods. 4715 while ((nm = claim_postponed_nmethod()) != NULL) { 4716 clean_nmethod_postponed(nm); 4717 } 4718 } 4719 }; 4720 4721 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 4722 4723 class G1KlassCleaningTask : public StackObj { 4724 BoolObjectClosure* _is_alive; 4725 volatile jint _clean_klass_tree_claimed; 4726 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 4727 4728 public: 4729 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 4730 _is_alive(is_alive), 4731 _clean_klass_tree_claimed(0), 4732 _klass_iterator() { 4733 } 4734 4735 private: 4736 bool claim_clean_klass_tree_task() { 4737 if (_clean_klass_tree_claimed) { 4738 return false; 4739 } 4740 4741 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 4742 } 4743 4744 InstanceKlass* claim_next_klass() { 4745 Klass* klass; 4746 do { 4747 klass =_klass_iterator.next_klass(); 4748 } while (klass != NULL && !klass->oop_is_instance()); 4749 4750 return (InstanceKlass*)klass; 4751 } 4752 4753 public: 4754 4755 void clean_klass(InstanceKlass* ik) { 4756 ik->clean_implementors_list(_is_alive); 4757 ik->clean_method_data(_is_alive); 4758 4759 // G1 specific cleanup work that has 4760 // been moved here to be done in parallel. 4761 ik->clean_dependent_nmethods(); 4762 } 4763 4764 void work() { 4765 ResourceMark rm; 4766 4767 // One worker will clean the subklass/sibling klass tree. 4768 if (claim_clean_klass_tree_task()) { 4769 Klass::clean_subklass_tree(_is_alive); 4770 } 4771 4772 // All workers will help cleaning the classes, 4773 InstanceKlass* klass; 4774 while ((klass = claim_next_klass()) != NULL) { 4775 clean_klass(klass); 4776 } 4777 } 4778 }; 4779 4780 // To minimize the remark pause times, the tasks below are done in parallel. 4781 class G1ParallelCleaningTask : public AbstractGangTask { 4782 private: 4783 G1StringSymbolTableUnlinkTask _string_symbol_task; 4784 G1CodeCacheUnloadingTask _code_cache_task; 4785 G1KlassCleaningTask _klass_cleaning_task; 4786 4787 public: 4788 // The constructor is run in the VMThread. 4789 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 4790 AbstractGangTask("Parallel Cleaning"), 4791 _string_symbol_task(is_alive, process_strings, process_symbols), 4792 _code_cache_task(num_workers, is_alive, unloading_occurred), 4793 _klass_cleaning_task(is_alive) { 4794 } 4795 4796 // The parallel work done by all worker threads. 4797 void work(uint worker_id) { 4798 // Do first pass of code cache cleaning. 4799 _code_cache_task.work_first_pass(worker_id); 4800 4801 // Let the threads mark that the first pass is done. 4802 _code_cache_task.barrier_mark(worker_id); 4803 4804 // Clean the Strings and Symbols. 4805 _string_symbol_task.work(worker_id); 4806 4807 // Wait for all workers to finish the first code cache cleaning pass. 4808 _code_cache_task.barrier_wait(worker_id); 4809 4810 // Do the second code cache cleaning work, which realize on 4811 // the liveness information gathered during the first pass. 4812 _code_cache_task.work_second_pass(worker_id); 4813 4814 // Clean all klasses that were not unloaded. 4815 _klass_cleaning_task.work(); 4816 } 4817 }; 4818 4819 4820 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 4821 bool process_strings, 4822 bool process_symbols, 4823 bool class_unloading_occurred) { 4824 uint n_workers = workers()->active_workers(); 4825 4826 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 4827 n_workers, class_unloading_occurred); 4828 set_par_threads(n_workers); 4829 workers()->run_task(&g1_unlink_task); 4830 set_par_threads(0); 4831 } 4832 4833 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 4834 bool process_strings, bool process_symbols) { 4835 { 4836 uint n_workers = _g1h->workers()->active_workers(); 4837 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 4838 set_par_threads(n_workers); 4839 workers()->run_task(&g1_unlink_task); 4840 set_par_threads(0); 4841 } 4842 4843 if (G1StringDedup::is_enabled()) { 4844 G1StringDedup::unlink(is_alive); 4845 } 4846 } 4847 4848 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 4849 private: 4850 DirtyCardQueueSet* _queue; 4851 public: 4852 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 4853 4854 virtual void work(uint worker_id) { 4855 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4856 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 4857 4858 RedirtyLoggedCardTableEntryClosure cl; 4859 _queue->par_apply_closure_to_all_completed_buffers(&cl); 4860 4861 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed()); 4862 } 4863 }; 4864 4865 void G1CollectedHeap::redirty_logged_cards() { 4866 double redirty_logged_cards_start = os::elapsedTime(); 4867 4868 uint n_workers = _g1h->workers()->active_workers(); 4869 4870 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 4871 dirty_card_queue_set().reset_for_par_iteration(); 4872 set_par_threads(n_workers); 4873 workers()->run_task(&redirty_task); 4874 set_par_threads(0); 4875 4876 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 4877 dcq.merge_bufferlists(&dirty_card_queue_set()); 4878 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 4879 4880 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 4881 } 4882 4883 // Weak Reference Processing support 4884 4885 // An always "is_alive" closure that is used to preserve referents. 4886 // If the object is non-null then it's alive. Used in the preservation 4887 // of referent objects that are pointed to by reference objects 4888 // discovered by the CM ref processor. 4889 class G1AlwaysAliveClosure: public BoolObjectClosure { 4890 G1CollectedHeap* _g1; 4891 public: 4892 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4893 bool do_object_b(oop p) { 4894 if (p != NULL) { 4895 return true; 4896 } 4897 return false; 4898 } 4899 }; 4900 4901 bool G1STWIsAliveClosure::do_object_b(oop p) { 4902 // An object is reachable if it is outside the collection set, 4903 // or is inside and copied. 4904 return !_g1->obj_in_cs(p) || p->is_forwarded(); 4905 } 4906 4907 // Non Copying Keep Alive closure 4908 class G1KeepAliveClosure: public OopClosure { 4909 G1CollectedHeap* _g1; 4910 public: 4911 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4912 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 4913 void do_oop(oop* p) { 4914 oop obj = *p; 4915 assert(obj != NULL, "the caller should have filtered out NULL values"); 4916 4917 const InCSetState cset_state = _g1->in_cset_state(obj); 4918 if (!cset_state.is_in_cset_or_humongous()) { 4919 return; 4920 } 4921 if (cset_state.is_in_cset()) { 4922 assert( obj->is_forwarded(), "invariant" ); 4923 *p = obj->forwardee(); 4924 } else { 4925 assert(!obj->is_forwarded(), "invariant" ); 4926 assert(cset_state.is_humongous(), 4927 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value())); 4928 _g1->set_humongous_is_live(obj); 4929 } 4930 } 4931 }; 4932 4933 // Copying Keep Alive closure - can be called from both 4934 // serial and parallel code as long as different worker 4935 // threads utilize different G1ParScanThreadState instances 4936 // and different queues. 4937 4938 class G1CopyingKeepAliveClosure: public OopClosure { 4939 G1CollectedHeap* _g1h; 4940 OopClosure* _copy_non_heap_obj_cl; 4941 G1ParScanThreadState* _par_scan_state; 4942 4943 public: 4944 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 4945 OopClosure* non_heap_obj_cl, 4946 G1ParScanThreadState* pss): 4947 _g1h(g1h), 4948 _copy_non_heap_obj_cl(non_heap_obj_cl), 4949 _par_scan_state(pss) 4950 {} 4951 4952 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 4953 virtual void do_oop( oop* p) { do_oop_work(p); } 4954 4955 template <class T> void do_oop_work(T* p) { 4956 oop obj = oopDesc::load_decode_heap_oop(p); 4957 4958 if (_g1h->is_in_cset_or_humongous(obj)) { 4959 // If the referent object has been forwarded (either copied 4960 // to a new location or to itself in the event of an 4961 // evacuation failure) then we need to update the reference 4962 // field and, if both reference and referent are in the G1 4963 // heap, update the RSet for the referent. 4964 // 4965 // If the referent has not been forwarded then we have to keep 4966 // it alive by policy. Therefore we have copy the referent. 4967 // 4968 // If the reference field is in the G1 heap then we can push 4969 // on the PSS queue. When the queue is drained (after each 4970 // phase of reference processing) the object and it's followers 4971 // will be copied, the reference field set to point to the 4972 // new location, and the RSet updated. Otherwise we need to 4973 // use the the non-heap or metadata closures directly to copy 4974 // the referent object and update the pointer, while avoiding 4975 // updating the RSet. 4976 4977 if (_g1h->is_in_g1_reserved(p)) { 4978 _par_scan_state->push_on_queue(p); 4979 } else { 4980 assert(!Metaspace::contains((const void*)p), 4981 err_msg("Unexpectedly found a pointer from metadata: " 4982 PTR_FORMAT, p)); 4983 _copy_non_heap_obj_cl->do_oop(p); 4984 } 4985 } 4986 } 4987 }; 4988 4989 // Serial drain queue closure. Called as the 'complete_gc' 4990 // closure for each discovered list in some of the 4991 // reference processing phases. 4992 4993 class G1STWDrainQueueClosure: public VoidClosure { 4994 protected: 4995 G1CollectedHeap* _g1h; 4996 G1ParScanThreadState* _par_scan_state; 4997 4998 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4999 5000 public: 5001 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5002 _g1h(g1h), 5003 _par_scan_state(pss) 5004 { } 5005 5006 void do_void() { 5007 G1ParScanThreadState* const pss = par_scan_state(); 5008 pss->trim_queue(); 5009 } 5010 }; 5011 5012 // Parallel Reference Processing closures 5013 5014 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5015 // processing during G1 evacuation pauses. 5016 5017 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5018 private: 5019 G1CollectedHeap* _g1h; 5020 RefToScanQueueSet* _queues; 5021 FlexibleWorkGang* _workers; 5022 int _active_workers; 5023 5024 public: 5025 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5026 FlexibleWorkGang* workers, 5027 RefToScanQueueSet *task_queues, 5028 int n_workers) : 5029 _g1h(g1h), 5030 _queues(task_queues), 5031 _workers(workers), 5032 _active_workers(n_workers) 5033 { 5034 assert(n_workers > 0, "shouldn't call this otherwise"); 5035 } 5036 5037 // Executes the given task using concurrent marking worker threads. 5038 virtual void execute(ProcessTask& task); 5039 virtual void execute(EnqueueTask& task); 5040 }; 5041 5042 // Gang task for possibly parallel reference processing 5043 5044 class G1STWRefProcTaskProxy: public AbstractGangTask { 5045 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5046 ProcessTask& _proc_task; 5047 G1CollectedHeap* _g1h; 5048 RefToScanQueueSet *_task_queues; 5049 ParallelTaskTerminator* _terminator; 5050 5051 public: 5052 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5053 G1CollectedHeap* g1h, 5054 RefToScanQueueSet *task_queues, 5055 ParallelTaskTerminator* terminator) : 5056 AbstractGangTask("Process reference objects in parallel"), 5057 _proc_task(proc_task), 5058 _g1h(g1h), 5059 _task_queues(task_queues), 5060 _terminator(terminator) 5061 {} 5062 5063 virtual void work(uint worker_id) { 5064 // The reference processing task executed by a single worker. 5065 ResourceMark rm; 5066 HandleMark hm; 5067 5068 G1STWIsAliveClosure is_alive(_g1h); 5069 5070 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5071 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5072 5073 pss.set_evac_failure_closure(&evac_failure_cl); 5074 5075 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5076 5077 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5078 5079 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5080 5081 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5082 // We also need to mark copied objects. 5083 copy_non_heap_cl = ©_mark_non_heap_cl; 5084 } 5085 5086 // Keep alive closure. 5087 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5088 5089 // Complete GC closure 5090 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5091 5092 // Call the reference processing task's work routine. 5093 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5094 5095 // Note we cannot assert that the refs array is empty here as not all 5096 // of the processing tasks (specifically phase2 - pp2_work) execute 5097 // the complete_gc closure (which ordinarily would drain the queue) so 5098 // the queue may not be empty. 5099 } 5100 }; 5101 5102 // Driver routine for parallel reference processing. 5103 // Creates an instance of the ref processing gang 5104 // task and has the worker threads execute it. 5105 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5106 assert(_workers != NULL, "Need parallel worker threads."); 5107 5108 ParallelTaskTerminator terminator(_active_workers, _queues); 5109 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5110 5111 _g1h->set_par_threads(_active_workers); 5112 _workers->run_task(&proc_task_proxy); 5113 _g1h->set_par_threads(0); 5114 } 5115 5116 // Gang task for parallel reference enqueueing. 5117 5118 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5119 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5120 EnqueueTask& _enq_task; 5121 5122 public: 5123 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5124 AbstractGangTask("Enqueue reference objects in parallel"), 5125 _enq_task(enq_task) 5126 { } 5127 5128 virtual void work(uint worker_id) { 5129 _enq_task.work(worker_id); 5130 } 5131 }; 5132 5133 // Driver routine for parallel reference enqueueing. 5134 // Creates an instance of the ref enqueueing gang 5135 // task and has the worker threads execute it. 5136 5137 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5138 assert(_workers != NULL, "Need parallel worker threads."); 5139 5140 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5141 5142 _g1h->set_par_threads(_active_workers); 5143 _workers->run_task(&enq_task_proxy); 5144 _g1h->set_par_threads(0); 5145 } 5146 5147 // End of weak reference support closures 5148 5149 // Abstract task used to preserve (i.e. copy) any referent objects 5150 // that are in the collection set and are pointed to by reference 5151 // objects discovered by the CM ref processor. 5152 5153 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5154 protected: 5155 G1CollectedHeap* _g1h; 5156 RefToScanQueueSet *_queues; 5157 ParallelTaskTerminator _terminator; 5158 uint _n_workers; 5159 5160 public: 5161 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5162 AbstractGangTask("ParPreserveCMReferents"), 5163 _g1h(g1h), 5164 _queues(task_queues), 5165 _terminator(workers, _queues), 5166 _n_workers(workers) 5167 { } 5168 5169 void work(uint worker_id) { 5170 ResourceMark rm; 5171 HandleMark hm; 5172 5173 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5174 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5175 5176 pss.set_evac_failure_closure(&evac_failure_cl); 5177 5178 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5179 5180 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5181 5182 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5183 5184 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5185 5186 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5187 // We also need to mark copied objects. 5188 copy_non_heap_cl = ©_mark_non_heap_cl; 5189 } 5190 5191 // Is alive closure 5192 G1AlwaysAliveClosure always_alive(_g1h); 5193 5194 // Copying keep alive closure. Applied to referent objects that need 5195 // to be copied. 5196 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5197 5198 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5199 5200 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5201 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5202 5203 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5204 // So this must be true - but assert just in case someone decides to 5205 // change the worker ids. 5206 assert(worker_id < limit, "sanity"); 5207 assert(!rp->discovery_is_atomic(), "check this code"); 5208 5209 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5210 for (uint idx = worker_id; idx < limit; idx += stride) { 5211 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5212 5213 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5214 while (iter.has_next()) { 5215 // Since discovery is not atomic for the CM ref processor, we 5216 // can see some null referent objects. 5217 iter.load_ptrs(DEBUG_ONLY(true)); 5218 oop ref = iter.obj(); 5219 5220 // This will filter nulls. 5221 if (iter.is_referent_alive()) { 5222 iter.make_referent_alive(); 5223 } 5224 iter.move_to_next(); 5225 } 5226 } 5227 5228 // Drain the queue - which may cause stealing 5229 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5230 drain_queue.do_void(); 5231 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5232 assert(pss.queue_is_empty(), "should be"); 5233 } 5234 }; 5235 5236 // Weak Reference processing during an evacuation pause (part 1). 5237 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5238 double ref_proc_start = os::elapsedTime(); 5239 5240 ReferenceProcessor* rp = _ref_processor_stw; 5241 assert(rp->discovery_enabled(), "should have been enabled"); 5242 5243 // Any reference objects, in the collection set, that were 'discovered' 5244 // by the CM ref processor should have already been copied (either by 5245 // applying the external root copy closure to the discovered lists, or 5246 // by following an RSet entry). 5247 // 5248 // But some of the referents, that are in the collection set, that these 5249 // reference objects point to may not have been copied: the STW ref 5250 // processor would have seen that the reference object had already 5251 // been 'discovered' and would have skipped discovering the reference, 5252 // but would not have treated the reference object as a regular oop. 5253 // As a result the copy closure would not have been applied to the 5254 // referent object. 5255 // 5256 // We need to explicitly copy these referent objects - the references 5257 // will be processed at the end of remarking. 5258 // 5259 // We also need to do this copying before we process the reference 5260 // objects discovered by the STW ref processor in case one of these 5261 // referents points to another object which is also referenced by an 5262 // object discovered by the STW ref processor. 5263 5264 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers"); 5265 5266 set_par_threads(no_of_gc_workers); 5267 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5268 no_of_gc_workers, 5269 _task_queues); 5270 5271 workers()->run_task(&keep_cm_referents); 5272 5273 set_par_threads(0); 5274 5275 // Closure to test whether a referent is alive. 5276 G1STWIsAliveClosure is_alive(this); 5277 5278 // Even when parallel reference processing is enabled, the processing 5279 // of JNI refs is serial and performed serially by the current thread 5280 // rather than by a worker. The following PSS will be used for processing 5281 // JNI refs. 5282 5283 // Use only a single queue for this PSS. 5284 G1ParScanThreadState pss(this, 0, NULL); 5285 5286 // We do not embed a reference processor in the copying/scanning 5287 // closures while we're actually processing the discovered 5288 // reference objects. 5289 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5290 5291 pss.set_evac_failure_closure(&evac_failure_cl); 5292 5293 assert(pss.queue_is_empty(), "pre-condition"); 5294 5295 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5296 5297 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5298 5299 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5300 5301 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5302 // We also need to mark copied objects. 5303 copy_non_heap_cl = ©_mark_non_heap_cl; 5304 } 5305 5306 // Keep alive closure. 5307 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss); 5308 5309 // Serial Complete GC closure 5310 G1STWDrainQueueClosure drain_queue(this, &pss); 5311 5312 // Setup the soft refs policy... 5313 rp->setup_policy(false); 5314 5315 ReferenceProcessorStats stats; 5316 if (!rp->processing_is_mt()) { 5317 // Serial reference processing... 5318 stats = rp->process_discovered_references(&is_alive, 5319 &keep_alive, 5320 &drain_queue, 5321 NULL, 5322 _gc_timer_stw, 5323 _gc_tracer_stw->gc_id()); 5324 } else { 5325 // Parallel reference processing 5326 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5327 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5328 5329 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5330 stats = rp->process_discovered_references(&is_alive, 5331 &keep_alive, 5332 &drain_queue, 5333 &par_task_executor, 5334 _gc_timer_stw, 5335 _gc_tracer_stw->gc_id()); 5336 } 5337 5338 _gc_tracer_stw->report_gc_reference_stats(stats); 5339 5340 // We have completed copying any necessary live referent objects. 5341 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5342 5343 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5344 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5345 } 5346 5347 // Weak Reference processing during an evacuation pause (part 2). 5348 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5349 double ref_enq_start = os::elapsedTime(); 5350 5351 ReferenceProcessor* rp = _ref_processor_stw; 5352 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5353 5354 // Now enqueue any remaining on the discovered lists on to 5355 // the pending list. 5356 if (!rp->processing_is_mt()) { 5357 // Serial reference processing... 5358 rp->enqueue_discovered_references(); 5359 } else { 5360 // Parallel reference enqueueing 5361 5362 assert(no_of_gc_workers == workers()->active_workers(), 5363 "Need to reset active workers"); 5364 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5365 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5366 5367 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5368 rp->enqueue_discovered_references(&par_task_executor); 5369 } 5370 5371 rp->verify_no_references_recorded(); 5372 assert(!rp->discovery_enabled(), "should have been disabled"); 5373 5374 // FIXME 5375 // CM's reference processing also cleans up the string and symbol tables. 5376 // Should we do that here also? We could, but it is a serial operation 5377 // and could significantly increase the pause time. 5378 5379 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5380 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5381 } 5382 5383 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5384 _expand_heap_after_alloc_failure = true; 5385 _evacuation_failed = false; 5386 5387 // Should G1EvacuationFailureALot be in effect for this GC? 5388 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5389 5390 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5391 5392 // Disable the hot card cache. 5393 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5394 hot_card_cache->reset_hot_cache_claimed_index(); 5395 hot_card_cache->set_use_cache(false); 5396 5397 const uint n_workers = workers()->active_workers(); 5398 assert(UseDynamicNumberOfGCThreads || 5399 n_workers == workers()->total_workers(), 5400 "If not dynamic should be using all the workers"); 5401 set_par_threads(n_workers); 5402 5403 5404 init_for_evac_failure(NULL); 5405 5406 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5407 double start_par_time_sec = os::elapsedTime(); 5408 double end_par_time_sec; 5409 5410 { 5411 G1RootProcessor root_processor(this); 5412 G1ParTask g1_par_task(this, _task_queues, &root_processor); 5413 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5414 if (g1_policy()->during_initial_mark_pause()) { 5415 ClassLoaderDataGraph::clear_claimed_marks(); 5416 } 5417 5418 // The individual threads will set their evac-failure closures. 5419 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr(); 5420 // These tasks use ShareHeap::_process_strong_tasks 5421 assert(UseDynamicNumberOfGCThreads || 5422 workers()->active_workers() == workers()->total_workers(), 5423 "If not dynamic should be using all the workers"); 5424 workers()->run_task(&g1_par_task); 5425 end_par_time_sec = os::elapsedTime(); 5426 5427 // Closing the inner scope will execute the destructor 5428 // for the G1RootProcessor object. We record the current 5429 // elapsed time before closing the scope so that time 5430 // taken for the destructor is NOT included in the 5431 // reported parallel time. 5432 } 5433 5434 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 5435 5436 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5437 phase_times->record_par_time(par_time_ms); 5438 5439 double code_root_fixup_time_ms = 5440 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5441 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 5442 5443 set_par_threads(0); 5444 5445 // Process any discovered reference objects - we have 5446 // to do this _before_ we retire the GC alloc regions 5447 // as we may have to copy some 'reachable' referent 5448 // objects (and their reachable sub-graphs) that were 5449 // not copied during the pause. 5450 process_discovered_references(n_workers); 5451 5452 if (G1StringDedup::is_enabled()) { 5453 double fixup_start = os::elapsedTime(); 5454 5455 G1STWIsAliveClosure is_alive(this); 5456 G1KeepAliveClosure keep_alive(this); 5457 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times); 5458 5459 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 5460 phase_times->record_string_dedup_fixup_time(fixup_time_ms); 5461 } 5462 5463 _allocator->release_gc_alloc_regions(n_workers, evacuation_info); 5464 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5465 5466 // Reset and re-enable the hot card cache. 5467 // Note the counts for the cards in the regions in the 5468 // collection set are reset when the collection set is freed. 5469 hot_card_cache->reset_hot_cache(); 5470 hot_card_cache->set_use_cache(true); 5471 5472 purge_code_root_memory(); 5473 5474 finalize_for_evac_failure(); 5475 5476 if (evacuation_failed()) { 5477 remove_self_forwarding_pointers(); 5478 5479 // Reset the G1EvacuationFailureALot counters and flags 5480 // Note: the values are reset only when an actual 5481 // evacuation failure occurs. 5482 NOT_PRODUCT(reset_evacuation_should_fail();) 5483 } 5484 5485 // Enqueue any remaining references remaining on the STW 5486 // reference processor's discovered lists. We need to do 5487 // this after the card table is cleaned (and verified) as 5488 // the act of enqueueing entries on to the pending list 5489 // will log these updates (and dirty their associated 5490 // cards). We need these updates logged to update any 5491 // RSets. 5492 enqueue_discovered_references(n_workers); 5493 5494 redirty_logged_cards(); 5495 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5496 } 5497 5498 void G1CollectedHeap::free_region(HeapRegion* hr, 5499 FreeRegionList* free_list, 5500 bool par, 5501 bool locked) { 5502 assert(!hr->is_free(), "the region should not be free"); 5503 assert(!hr->is_empty(), "the region should not be empty"); 5504 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 5505 assert(free_list != NULL, "pre-condition"); 5506 5507 if (G1VerifyBitmaps) { 5508 MemRegion mr(hr->bottom(), hr->end()); 5509 concurrent_mark()->clearRangePrevBitmap(mr); 5510 } 5511 5512 // Clear the card counts for this region. 5513 // Note: we only need to do this if the region is not young 5514 // (since we don't refine cards in young regions). 5515 if (!hr->is_young()) { 5516 _cg1r->hot_card_cache()->reset_card_counts(hr); 5517 } 5518 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5519 free_list->add_ordered(hr); 5520 } 5521 5522 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5523 FreeRegionList* free_list, 5524 bool par) { 5525 assert(hr->is_starts_humongous(), "this is only for starts humongous regions"); 5526 assert(free_list != NULL, "pre-condition"); 5527 5528 size_t hr_capacity = hr->capacity(); 5529 // We need to read this before we make the region non-humongous, 5530 // otherwise the information will be gone. 5531 uint last_index = hr->last_hc_index(); 5532 hr->clear_humongous(); 5533 free_region(hr, free_list, par); 5534 5535 uint i = hr->hrm_index() + 1; 5536 while (i < last_index) { 5537 HeapRegion* curr_hr = region_at(i); 5538 assert(curr_hr->is_continues_humongous(), "invariant"); 5539 curr_hr->clear_humongous(); 5540 free_region(curr_hr, free_list, par); 5541 i += 1; 5542 } 5543 } 5544 5545 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 5546 const HeapRegionSetCount& humongous_regions_removed) { 5547 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5548 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5549 _old_set.bulk_remove(old_regions_removed); 5550 _humongous_set.bulk_remove(humongous_regions_removed); 5551 } 5552 5553 } 5554 5555 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 5556 assert(list != NULL, "list can't be null"); 5557 if (!list->is_empty()) { 5558 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5559 _hrm.insert_list_into_free_list(list); 5560 } 5561 } 5562 5563 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 5564 _allocator->decrease_used(bytes); 5565 } 5566 5567 class G1ParCleanupCTTask : public AbstractGangTask { 5568 G1SATBCardTableModRefBS* _ct_bs; 5569 G1CollectedHeap* _g1h; 5570 HeapRegion* volatile _su_head; 5571 public: 5572 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 5573 G1CollectedHeap* g1h) : 5574 AbstractGangTask("G1 Par Cleanup CT Task"), 5575 _ct_bs(ct_bs), _g1h(g1h) { } 5576 5577 void work(uint worker_id) { 5578 HeapRegion* r; 5579 while (r = _g1h->pop_dirty_cards_region()) { 5580 clear_cards(r); 5581 } 5582 } 5583 5584 void clear_cards(HeapRegion* r) { 5585 // Cards of the survivors should have already been dirtied. 5586 if (!r->is_survivor()) { 5587 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5588 } 5589 } 5590 }; 5591 5592 #ifndef PRODUCT 5593 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5594 G1CollectedHeap* _g1h; 5595 G1SATBCardTableModRefBS* _ct_bs; 5596 public: 5597 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 5598 : _g1h(g1h), _ct_bs(ct_bs) { } 5599 virtual bool doHeapRegion(HeapRegion* r) { 5600 if (r->is_survivor()) { 5601 _g1h->verify_dirty_region(r); 5602 } else { 5603 _g1h->verify_not_dirty_region(r); 5604 } 5605 return false; 5606 } 5607 }; 5608 5609 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5610 // All of the region should be clean. 5611 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5612 MemRegion mr(hr->bottom(), hr->end()); 5613 ct_bs->verify_not_dirty_region(mr); 5614 } 5615 5616 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5617 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5618 // dirty allocated blocks as they allocate them. The thread that 5619 // retires each region and replaces it with a new one will do a 5620 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5621 // not dirty that area (one less thing to have to do while holding 5622 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5623 // is dirty. 5624 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5625 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5626 if (hr->is_young()) { 5627 ct_bs->verify_g1_young_region(mr); 5628 } else { 5629 ct_bs->verify_dirty_region(mr); 5630 } 5631 } 5632 5633 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5634 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5635 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5636 verify_dirty_region(hr); 5637 } 5638 } 5639 5640 void G1CollectedHeap::verify_dirty_young_regions() { 5641 verify_dirty_young_list(_young_list->first_region()); 5642 } 5643 5644 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 5645 HeapWord* tams, HeapWord* end) { 5646 guarantee(tams <= end, 5647 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end)); 5648 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 5649 if (result < end) { 5650 gclog_or_tty->cr(); 5651 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT, 5652 bitmap_name, result); 5653 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT, 5654 bitmap_name, tams, end); 5655 return false; 5656 } 5657 return true; 5658 } 5659 5660 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 5661 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 5662 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 5663 5664 HeapWord* bottom = hr->bottom(); 5665 HeapWord* ptams = hr->prev_top_at_mark_start(); 5666 HeapWord* ntams = hr->next_top_at_mark_start(); 5667 HeapWord* end = hr->end(); 5668 5669 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 5670 5671 bool res_n = true; 5672 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 5673 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 5674 // if we happen to be in that state. 5675 if (mark_in_progress() || !_cmThread->in_progress()) { 5676 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 5677 } 5678 if (!res_p || !res_n) { 5679 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT, 5680 HR_FORMAT_PARAMS(hr)); 5681 gclog_or_tty->print_cr("#### Caller: %s", caller); 5682 return false; 5683 } 5684 return true; 5685 } 5686 5687 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 5688 if (!G1VerifyBitmaps) return; 5689 5690 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 5691 } 5692 5693 class G1VerifyBitmapClosure : public HeapRegionClosure { 5694 private: 5695 const char* _caller; 5696 G1CollectedHeap* _g1h; 5697 bool _failures; 5698 5699 public: 5700 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 5701 _caller(caller), _g1h(g1h), _failures(false) { } 5702 5703 bool failures() { return _failures; } 5704 5705 virtual bool doHeapRegion(HeapRegion* hr) { 5706 if (hr->is_continues_humongous()) return false; 5707 5708 bool result = _g1h->verify_bitmaps(_caller, hr); 5709 if (!result) { 5710 _failures = true; 5711 } 5712 return false; 5713 } 5714 }; 5715 5716 void G1CollectedHeap::check_bitmaps(const char* caller) { 5717 if (!G1VerifyBitmaps) return; 5718 5719 G1VerifyBitmapClosure cl(caller, this); 5720 heap_region_iterate(&cl); 5721 guarantee(!cl.failures(), "bitmap verification"); 5722 } 5723 5724 class G1CheckCSetFastTableClosure : public HeapRegionClosure { 5725 private: 5726 bool _failures; 5727 public: 5728 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { } 5729 5730 virtual bool doHeapRegion(HeapRegion* hr) { 5731 uint i = hr->hrm_index(); 5732 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i); 5733 if (hr->is_humongous()) { 5734 if (hr->in_collection_set()) { 5735 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i); 5736 _failures = true; 5737 return true; 5738 } 5739 if (cset_state.is_in_cset()) { 5740 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i); 5741 _failures = true; 5742 return true; 5743 } 5744 if (hr->is_continues_humongous() && cset_state.is_humongous()) { 5745 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i); 5746 _failures = true; 5747 return true; 5748 } 5749 } else { 5750 if (cset_state.is_humongous()) { 5751 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i); 5752 _failures = true; 5753 return true; 5754 } 5755 if (hr->in_collection_set() != cset_state.is_in_cset()) { 5756 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u", 5757 hr->in_collection_set(), cset_state.value(), i); 5758 _failures = true; 5759 return true; 5760 } 5761 if (cset_state.is_in_cset()) { 5762 if (hr->is_young() != (cset_state.is_young())) { 5763 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u", 5764 hr->is_young(), cset_state.value(), i); 5765 _failures = true; 5766 return true; 5767 } 5768 if (hr->is_old() != (cset_state.is_old())) { 5769 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u", 5770 hr->is_old(), cset_state.value(), i); 5771 _failures = true; 5772 return true; 5773 } 5774 } 5775 } 5776 return false; 5777 } 5778 5779 bool failures() const { return _failures; } 5780 }; 5781 5782 bool G1CollectedHeap::check_cset_fast_test() { 5783 G1CheckCSetFastTableClosure cl; 5784 _hrm.iterate(&cl); 5785 return !cl.failures(); 5786 } 5787 #endif // PRODUCT 5788 5789 void G1CollectedHeap::cleanUpCardTable() { 5790 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5791 double start = os::elapsedTime(); 5792 5793 { 5794 // Iterate over the dirty cards region list. 5795 G1ParCleanupCTTask cleanup_task(ct_bs, this); 5796 5797 set_par_threads(); 5798 workers()->run_task(&cleanup_task); 5799 set_par_threads(0); 5800 #ifndef PRODUCT 5801 if (G1VerifyCTCleanup || VerifyAfterGC) { 5802 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 5803 heap_region_iterate(&cleanup_verifier); 5804 } 5805 #endif 5806 } 5807 5808 double elapsed = os::elapsedTime() - start; 5809 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 5810 } 5811 5812 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 5813 size_t pre_used = 0; 5814 FreeRegionList local_free_list("Local List for CSet Freeing"); 5815 5816 double young_time_ms = 0.0; 5817 double non_young_time_ms = 0.0; 5818 5819 // Since the collection set is a superset of the the young list, 5820 // all we need to do to clear the young list is clear its 5821 // head and length, and unlink any young regions in the code below 5822 _young_list->clear(); 5823 5824 G1CollectorPolicy* policy = g1_policy(); 5825 5826 double start_sec = os::elapsedTime(); 5827 bool non_young = true; 5828 5829 HeapRegion* cur = cs_head; 5830 int age_bound = -1; 5831 size_t rs_lengths = 0; 5832 5833 while (cur != NULL) { 5834 assert(!is_on_master_free_list(cur), "sanity"); 5835 if (non_young) { 5836 if (cur->is_young()) { 5837 double end_sec = os::elapsedTime(); 5838 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5839 non_young_time_ms += elapsed_ms; 5840 5841 start_sec = os::elapsedTime(); 5842 non_young = false; 5843 } 5844 } else { 5845 if (!cur->is_young()) { 5846 double end_sec = os::elapsedTime(); 5847 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5848 young_time_ms += elapsed_ms; 5849 5850 start_sec = os::elapsedTime(); 5851 non_young = true; 5852 } 5853 } 5854 5855 rs_lengths += cur->rem_set()->occupied_locked(); 5856 5857 HeapRegion* next = cur->next_in_collection_set(); 5858 assert(cur->in_collection_set(), "bad CS"); 5859 cur->set_next_in_collection_set(NULL); 5860 clear_in_cset(cur); 5861 5862 if (cur->is_young()) { 5863 int index = cur->young_index_in_cset(); 5864 assert(index != -1, "invariant"); 5865 assert((uint) index < policy->young_cset_region_length(), "invariant"); 5866 size_t words_survived = _surviving_young_words[index]; 5867 cur->record_surv_words_in_group(words_survived); 5868 5869 // At this point the we have 'popped' cur from the collection set 5870 // (linked via next_in_collection_set()) but it is still in the 5871 // young list (linked via next_young_region()). Clear the 5872 // _next_young_region field. 5873 cur->set_next_young_region(NULL); 5874 } else { 5875 int index = cur->young_index_in_cset(); 5876 assert(index == -1, "invariant"); 5877 } 5878 5879 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 5880 (!cur->is_young() && cur->young_index_in_cset() == -1), 5881 "invariant" ); 5882 5883 if (!cur->evacuation_failed()) { 5884 MemRegion used_mr = cur->used_region(); 5885 5886 // And the region is empty. 5887 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 5888 pre_used += cur->used(); 5889 free_region(cur, &local_free_list, false /* par */, true /* locked */); 5890 } else { 5891 cur->uninstall_surv_rate_group(); 5892 if (cur->is_young()) { 5893 cur->set_young_index_in_cset(-1); 5894 } 5895 cur->set_evacuation_failed(false); 5896 // The region is now considered to be old. 5897 cur->set_old(); 5898 _old_set.add(cur); 5899 evacuation_info.increment_collectionset_used_after(cur->used()); 5900 } 5901 cur = next; 5902 } 5903 5904 evacuation_info.set_regions_freed(local_free_list.length()); 5905 policy->record_max_rs_lengths(rs_lengths); 5906 policy->cset_regions_freed(); 5907 5908 double end_sec = os::elapsedTime(); 5909 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5910 5911 if (non_young) { 5912 non_young_time_ms += elapsed_ms; 5913 } else { 5914 young_time_ms += elapsed_ms; 5915 } 5916 5917 prepend_to_freelist(&local_free_list); 5918 decrement_summary_bytes(pre_used); 5919 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 5920 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 5921 } 5922 5923 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 5924 private: 5925 FreeRegionList* _free_region_list; 5926 HeapRegionSet* _proxy_set; 5927 HeapRegionSetCount _humongous_regions_removed; 5928 size_t _freed_bytes; 5929 public: 5930 5931 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 5932 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 5933 } 5934 5935 virtual bool doHeapRegion(HeapRegion* r) { 5936 if (!r->is_starts_humongous()) { 5937 return false; 5938 } 5939 5940 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 5941 5942 oop obj = (oop)r->bottom(); 5943 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 5944 5945 // The following checks whether the humongous object is live are sufficient. 5946 // The main additional check (in addition to having a reference from the roots 5947 // or the young gen) is whether the humongous object has a remembered set entry. 5948 // 5949 // A humongous object cannot be live if there is no remembered set for it 5950 // because: 5951 // - there can be no references from within humongous starts regions referencing 5952 // the object because we never allocate other objects into them. 5953 // (I.e. there are no intra-region references that may be missed by the 5954 // remembered set) 5955 // - as soon there is a remembered set entry to the humongous starts region 5956 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 5957 // until the end of a concurrent mark. 5958 // 5959 // It is not required to check whether the object has been found dead by marking 5960 // or not, in fact it would prevent reclamation within a concurrent cycle, as 5961 // all objects allocated during that time are considered live. 5962 // SATB marking is even more conservative than the remembered set. 5963 // So if at this point in the collection there is no remembered set entry, 5964 // nobody has a reference to it. 5965 // At the start of collection we flush all refinement logs, and remembered sets 5966 // are completely up-to-date wrt to references to the humongous object. 5967 // 5968 // Other implementation considerations: 5969 // - never consider object arrays at this time because they would pose 5970 // considerable effort for cleaning up the the remembered sets. This is 5971 // required because stale remembered sets might reference locations that 5972 // are currently allocated into. 5973 uint region_idx = r->hrm_index(); 5974 if (g1h->humongous_is_live(region_idx) || 5975 g1h->humongous_region_is_always_live(region_idx)) { 5976 5977 if (G1TraceEagerReclaimHumongousObjects) { 5978 gclog_or_tty->print_cr("Live humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d", 5979 region_idx, 5980 obj->size()*HeapWordSize, 5981 r->bottom(), 5982 r->region_num(), 5983 r->rem_set()->occupied(), 5984 r->rem_set()->strong_code_roots_list_length(), 5985 next_bitmap->isMarked(r->bottom()), 5986 g1h->humongous_is_live(region_idx), 5987 obj->is_objArray() 5988 ); 5989 } 5990 5991 return false; 5992 } 5993 5994 guarantee(!obj->is_objArray(), 5995 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.", 5996 r->bottom())); 5997 5998 if (G1TraceEagerReclaimHumongousObjects) { 5999 gclog_or_tty->print_cr("Dead humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d", 6000 region_idx, 6001 obj->size()*HeapWordSize, 6002 r->bottom(), 6003 r->region_num(), 6004 r->rem_set()->occupied(), 6005 r->rem_set()->strong_code_roots_list_length(), 6006 next_bitmap->isMarked(r->bottom()), 6007 g1h->humongous_is_live(region_idx), 6008 obj->is_objArray() 6009 ); 6010 } 6011 // Need to clear mark bit of the humongous object if already set. 6012 if (next_bitmap->isMarked(r->bottom())) { 6013 next_bitmap->clear(r->bottom()); 6014 } 6015 _freed_bytes += r->used(); 6016 r->set_containing_set(NULL); 6017 _humongous_regions_removed.increment(1u, r->capacity()); 6018 g1h->free_humongous_region(r, _free_region_list, false); 6019 6020 return false; 6021 } 6022 6023 HeapRegionSetCount& humongous_free_count() { 6024 return _humongous_regions_removed; 6025 } 6026 6027 size_t bytes_freed() const { 6028 return _freed_bytes; 6029 } 6030 6031 size_t humongous_reclaimed() const { 6032 return _humongous_regions_removed.length(); 6033 } 6034 }; 6035 6036 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 6037 assert_at_safepoint(true); 6038 6039 if (!G1EagerReclaimHumongousObjects || 6040 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) { 6041 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 6042 return; 6043 } 6044 6045 double start_time = os::elapsedTime(); 6046 6047 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 6048 6049 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 6050 heap_region_iterate(&cl); 6051 6052 HeapRegionSetCount empty_set; 6053 remove_from_old_sets(empty_set, cl.humongous_free_count()); 6054 6055 G1HRPrinter* hr_printer = _g1h->hr_printer(); 6056 if (hr_printer->is_active()) { 6057 FreeRegionListIterator iter(&local_cleanup_list); 6058 while (iter.more_available()) { 6059 HeapRegion* hr = iter.get_next(); 6060 hr_printer->cleanup(hr); 6061 } 6062 } 6063 6064 prepend_to_freelist(&local_cleanup_list); 6065 decrement_summary_bytes(cl.bytes_freed()); 6066 6067 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 6068 cl.humongous_reclaimed()); 6069 } 6070 6071 // This routine is similar to the above but does not record 6072 // any policy statistics or update free lists; we are abandoning 6073 // the current incremental collection set in preparation of a 6074 // full collection. After the full GC we will start to build up 6075 // the incremental collection set again. 6076 // This is only called when we're doing a full collection 6077 // and is immediately followed by the tearing down of the young list. 6078 6079 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6080 HeapRegion* cur = cs_head; 6081 6082 while (cur != NULL) { 6083 HeapRegion* next = cur->next_in_collection_set(); 6084 assert(cur->in_collection_set(), "bad CS"); 6085 cur->set_next_in_collection_set(NULL); 6086 clear_in_cset(cur); 6087 cur->set_young_index_in_cset(-1); 6088 cur = next; 6089 } 6090 } 6091 6092 void G1CollectedHeap::set_free_regions_coming() { 6093 if (G1ConcRegionFreeingVerbose) { 6094 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6095 "setting free regions coming"); 6096 } 6097 6098 assert(!free_regions_coming(), "pre-condition"); 6099 _free_regions_coming = true; 6100 } 6101 6102 void G1CollectedHeap::reset_free_regions_coming() { 6103 assert(free_regions_coming(), "pre-condition"); 6104 6105 { 6106 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6107 _free_regions_coming = false; 6108 SecondaryFreeList_lock->notify_all(); 6109 } 6110 6111 if (G1ConcRegionFreeingVerbose) { 6112 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6113 "reset free regions coming"); 6114 } 6115 } 6116 6117 void G1CollectedHeap::wait_while_free_regions_coming() { 6118 // Most of the time we won't have to wait, so let's do a quick test 6119 // first before we take the lock. 6120 if (!free_regions_coming()) { 6121 return; 6122 } 6123 6124 if (G1ConcRegionFreeingVerbose) { 6125 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6126 "waiting for free regions"); 6127 } 6128 6129 { 6130 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6131 while (free_regions_coming()) { 6132 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6133 } 6134 } 6135 6136 if (G1ConcRegionFreeingVerbose) { 6137 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6138 "done waiting for free regions"); 6139 } 6140 } 6141 6142 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6143 _young_list->push_region(hr); 6144 } 6145 6146 class NoYoungRegionsClosure: public HeapRegionClosure { 6147 private: 6148 bool _success; 6149 public: 6150 NoYoungRegionsClosure() : _success(true) { } 6151 bool doHeapRegion(HeapRegion* r) { 6152 if (r->is_young()) { 6153 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6154 r->bottom(), r->end()); 6155 _success = false; 6156 } 6157 return false; 6158 } 6159 bool success() { return _success; } 6160 }; 6161 6162 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6163 bool ret = _young_list->check_list_empty(check_sample); 6164 6165 if (check_heap) { 6166 NoYoungRegionsClosure closure; 6167 heap_region_iterate(&closure); 6168 ret = ret && closure.success(); 6169 } 6170 6171 return ret; 6172 } 6173 6174 class TearDownRegionSetsClosure : public HeapRegionClosure { 6175 private: 6176 HeapRegionSet *_old_set; 6177 6178 public: 6179 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6180 6181 bool doHeapRegion(HeapRegion* r) { 6182 if (r->is_old()) { 6183 _old_set->remove(r); 6184 } else { 6185 // We ignore free regions, we'll empty the free list afterwards. 6186 // We ignore young regions, we'll empty the young list afterwards. 6187 // We ignore humongous regions, we're not tearing down the 6188 // humongous regions set. 6189 assert(r->is_free() || r->is_young() || r->is_humongous(), 6190 "it cannot be another type"); 6191 } 6192 return false; 6193 } 6194 6195 ~TearDownRegionSetsClosure() { 6196 assert(_old_set->is_empty(), "post-condition"); 6197 } 6198 }; 6199 6200 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6201 assert_at_safepoint(true /* should_be_vm_thread */); 6202 6203 if (!free_list_only) { 6204 TearDownRegionSetsClosure cl(&_old_set); 6205 heap_region_iterate(&cl); 6206 6207 // Note that emptying the _young_list is postponed and instead done as 6208 // the first step when rebuilding the regions sets again. The reason for 6209 // this is that during a full GC string deduplication needs to know if 6210 // a collected region was young or old when the full GC was initiated. 6211 } 6212 _hrm.remove_all_free_regions(); 6213 } 6214 6215 class RebuildRegionSetsClosure : public HeapRegionClosure { 6216 private: 6217 bool _free_list_only; 6218 HeapRegionSet* _old_set; 6219 HeapRegionManager* _hrm; 6220 size_t _total_used; 6221 6222 public: 6223 RebuildRegionSetsClosure(bool free_list_only, 6224 HeapRegionSet* old_set, HeapRegionManager* hrm) : 6225 _free_list_only(free_list_only), 6226 _old_set(old_set), _hrm(hrm), _total_used(0) { 6227 assert(_hrm->num_free_regions() == 0, "pre-condition"); 6228 if (!free_list_only) { 6229 assert(_old_set->is_empty(), "pre-condition"); 6230 } 6231 } 6232 6233 bool doHeapRegion(HeapRegion* r) { 6234 if (r->is_continues_humongous()) { 6235 return false; 6236 } 6237 6238 if (r->is_empty()) { 6239 // Add free regions to the free list 6240 r->set_free(); 6241 r->set_allocation_context(AllocationContext::system()); 6242 _hrm->insert_into_free_list(r); 6243 } else if (!_free_list_only) { 6244 assert(!r->is_young(), "we should not come across young regions"); 6245 6246 if (r->is_humongous()) { 6247 // We ignore humongous regions, we left the humongous set unchanged 6248 } else { 6249 // Objects that were compacted would have ended up on regions 6250 // that were previously old or free. 6251 assert(r->is_free() || r->is_old(), "invariant"); 6252 // We now consider them old, so register as such. 6253 r->set_old(); 6254 _old_set->add(r); 6255 } 6256 _total_used += r->used(); 6257 } 6258 6259 return false; 6260 } 6261 6262 size_t total_used() { 6263 return _total_used; 6264 } 6265 }; 6266 6267 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6268 assert_at_safepoint(true /* should_be_vm_thread */); 6269 6270 if (!free_list_only) { 6271 _young_list->empty_list(); 6272 } 6273 6274 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 6275 heap_region_iterate(&cl); 6276 6277 if (!free_list_only) { 6278 _allocator->set_used(cl.total_used()); 6279 } 6280 assert(_allocator->used_unlocked() == recalculate_used(), 6281 err_msg("inconsistent _allocator->used_unlocked(), " 6282 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6283 _allocator->used_unlocked(), recalculate_used())); 6284 } 6285 6286 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6287 _refine_cte_cl->set_concurrent(concurrent); 6288 } 6289 6290 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6291 HeapRegion* hr = heap_region_containing(p); 6292 return hr->is_in(p); 6293 } 6294 6295 // Methods for the mutator alloc region 6296 6297 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6298 bool force) { 6299 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6300 assert(!force || g1_policy()->can_expand_young_list(), 6301 "if force is true we should be able to expand the young list"); 6302 bool young_list_full = g1_policy()->is_young_list_full(); 6303 if (force || !young_list_full) { 6304 HeapRegion* new_alloc_region = new_region(word_size, 6305 false /* is_old */, 6306 false /* do_expand */); 6307 if (new_alloc_region != NULL) { 6308 set_region_short_lived_locked(new_alloc_region); 6309 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6310 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6311 return new_alloc_region; 6312 } 6313 } 6314 return NULL; 6315 } 6316 6317 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6318 size_t allocated_bytes) { 6319 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6320 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 6321 6322 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6323 _allocator->increase_used(allocated_bytes); 6324 _hr_printer.retire(alloc_region); 6325 // We update the eden sizes here, when the region is retired, 6326 // instead of when it's allocated, since this is the point that its 6327 // used space has been recored in _summary_bytes_used. 6328 g1mm()->update_eden_size(); 6329 } 6330 6331 void G1CollectedHeap::set_par_threads() { 6332 // Don't change the number of workers. Use the value previously set 6333 // in the workgroup. 6334 uint n_workers = workers()->active_workers(); 6335 assert(UseDynamicNumberOfGCThreads || 6336 n_workers == workers()->total_workers(), 6337 "Otherwise should be using the total number of workers"); 6338 if (n_workers == 0) { 6339 assert(false, "Should have been set in prior evacuation pause."); 6340 n_workers = ParallelGCThreads; 6341 workers()->set_active_workers(n_workers); 6342 } 6343 set_par_threads(n_workers); 6344 } 6345 6346 // Methods for the GC alloc regions 6347 6348 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6349 uint count, 6350 InCSetState dest) { 6351 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6352 6353 if (count < g1_policy()->max_regions(dest)) { 6354 const bool is_survivor = (dest.is_young()); 6355 HeapRegion* new_alloc_region = new_region(word_size, 6356 !is_survivor, 6357 true /* do_expand */); 6358 if (new_alloc_region != NULL) { 6359 // We really only need to do this for old regions given that we 6360 // should never scan survivors. But it doesn't hurt to do it 6361 // for survivors too. 6362 new_alloc_region->record_timestamp(); 6363 if (is_survivor) { 6364 new_alloc_region->set_survivor(); 6365 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6366 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6367 } else { 6368 new_alloc_region->set_old(); 6369 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6370 check_bitmaps("Old Region Allocation", new_alloc_region); 6371 } 6372 bool during_im = g1_policy()->during_initial_mark_pause(); 6373 new_alloc_region->note_start_of_copying(during_im); 6374 return new_alloc_region; 6375 } 6376 } 6377 return NULL; 6378 } 6379 6380 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6381 size_t allocated_bytes, 6382 InCSetState dest) { 6383 bool during_im = g1_policy()->during_initial_mark_pause(); 6384 alloc_region->note_end_of_copying(during_im); 6385 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6386 if (dest.is_young()) { 6387 young_list()->add_survivor_region(alloc_region); 6388 } else { 6389 _old_set.add(alloc_region); 6390 } 6391 _hr_printer.retire(alloc_region); 6392 } 6393 6394 // Heap region set verification 6395 6396 class VerifyRegionListsClosure : public HeapRegionClosure { 6397 private: 6398 HeapRegionSet* _old_set; 6399 HeapRegionSet* _humongous_set; 6400 HeapRegionManager* _hrm; 6401 6402 public: 6403 HeapRegionSetCount _old_count; 6404 HeapRegionSetCount _humongous_count; 6405 HeapRegionSetCount _free_count; 6406 6407 VerifyRegionListsClosure(HeapRegionSet* old_set, 6408 HeapRegionSet* humongous_set, 6409 HeapRegionManager* hrm) : 6410 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm), 6411 _old_count(), _humongous_count(), _free_count(){ } 6412 6413 bool doHeapRegion(HeapRegion* hr) { 6414 if (hr->is_continues_humongous()) { 6415 return false; 6416 } 6417 6418 if (hr->is_young()) { 6419 // TODO 6420 } else if (hr->is_starts_humongous()) { 6421 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index())); 6422 _humongous_count.increment(1u, hr->capacity()); 6423 } else if (hr->is_empty()) { 6424 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index())); 6425 _free_count.increment(1u, hr->capacity()); 6426 } else if (hr->is_old()) { 6427 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index())); 6428 _old_count.increment(1u, hr->capacity()); 6429 } else { 6430 ShouldNotReachHere(); 6431 } 6432 return false; 6433 } 6434 6435 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) { 6436 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 6437 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6438 old_set->total_capacity_bytes(), _old_count.capacity())); 6439 6440 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 6441 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6442 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 6443 6444 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())); 6445 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6446 free_list->total_capacity_bytes(), _free_count.capacity())); 6447 } 6448 }; 6449 6450 void G1CollectedHeap::verify_region_sets() { 6451 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6452 6453 // First, check the explicit lists. 6454 _hrm.verify(); 6455 { 6456 // Given that a concurrent operation might be adding regions to 6457 // the secondary free list we have to take the lock before 6458 // verifying it. 6459 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6460 _secondary_free_list.verify_list(); 6461 } 6462 6463 // If a concurrent region freeing operation is in progress it will 6464 // be difficult to correctly attributed any free regions we come 6465 // across to the correct free list given that they might belong to 6466 // one of several (free_list, secondary_free_list, any local lists, 6467 // etc.). So, if that's the case we will skip the rest of the 6468 // verification operation. Alternatively, waiting for the concurrent 6469 // operation to complete will have a non-trivial effect on the GC's 6470 // operation (no concurrent operation will last longer than the 6471 // interval between two calls to verification) and it might hide 6472 // any issues that we would like to catch during testing. 6473 if (free_regions_coming()) { 6474 return; 6475 } 6476 6477 // Make sure we append the secondary_free_list on the free_list so 6478 // that all free regions we will come across can be safely 6479 // attributed to the free_list. 6480 append_secondary_free_list_if_not_empty_with_lock(); 6481 6482 // Finally, make sure that the region accounting in the lists is 6483 // consistent with what we see in the heap. 6484 6485 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm); 6486 heap_region_iterate(&cl); 6487 cl.verify_counts(&_old_set, &_humongous_set, &_hrm); 6488 } 6489 6490 // Optimized nmethod scanning 6491 6492 class RegisterNMethodOopClosure: public OopClosure { 6493 G1CollectedHeap* _g1h; 6494 nmethod* _nm; 6495 6496 template <class T> void do_oop_work(T* p) { 6497 T heap_oop = oopDesc::load_heap_oop(p); 6498 if (!oopDesc::is_null(heap_oop)) { 6499 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6500 HeapRegion* hr = _g1h->heap_region_containing(obj); 6501 assert(!hr->is_continues_humongous(), 6502 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6503 " starting at "HR_FORMAT, 6504 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6505 6506 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 6507 hr->add_strong_code_root_locked(_nm); 6508 } 6509 } 6510 6511 public: 6512 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6513 _g1h(g1h), _nm(nm) {} 6514 6515 void do_oop(oop* p) { do_oop_work(p); } 6516 void do_oop(narrowOop* p) { do_oop_work(p); } 6517 }; 6518 6519 class UnregisterNMethodOopClosure: public OopClosure { 6520 G1CollectedHeap* _g1h; 6521 nmethod* _nm; 6522 6523 template <class T> void do_oop_work(T* p) { 6524 T heap_oop = oopDesc::load_heap_oop(p); 6525 if (!oopDesc::is_null(heap_oop)) { 6526 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6527 HeapRegion* hr = _g1h->heap_region_containing(obj); 6528 assert(!hr->is_continues_humongous(), 6529 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6530 " starting at "HR_FORMAT, 6531 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6532 6533 hr->remove_strong_code_root(_nm); 6534 } 6535 } 6536 6537 public: 6538 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6539 _g1h(g1h), _nm(nm) {} 6540 6541 void do_oop(oop* p) { do_oop_work(p); } 6542 void do_oop(narrowOop* p) { do_oop_work(p); } 6543 }; 6544 6545 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6546 CollectedHeap::register_nmethod(nm); 6547 6548 guarantee(nm != NULL, "sanity"); 6549 RegisterNMethodOopClosure reg_cl(this, nm); 6550 nm->oops_do(®_cl); 6551 } 6552 6553 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6554 CollectedHeap::unregister_nmethod(nm); 6555 6556 guarantee(nm != NULL, "sanity"); 6557 UnregisterNMethodOopClosure reg_cl(this, nm); 6558 nm->oops_do(®_cl, true); 6559 } 6560 6561 void G1CollectedHeap::purge_code_root_memory() { 6562 double purge_start = os::elapsedTime(); 6563 G1CodeRootSet::purge(); 6564 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6565 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6566 } 6567 6568 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6569 G1CollectedHeap* _g1h; 6570 6571 public: 6572 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6573 _g1h(g1h) {} 6574 6575 void do_code_blob(CodeBlob* cb) { 6576 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6577 if (nm == NULL) { 6578 return; 6579 } 6580 6581 if (ScavengeRootsInCode) { 6582 _g1h->register_nmethod(nm); 6583 } 6584 } 6585 }; 6586 6587 void G1CollectedHeap::rebuild_strong_code_roots() { 6588 RebuildStrongCodeRootClosure blob_cl(this); 6589 CodeCache::blobs_do(&blob_cl); 6590 }