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 #include "utilities/stack.inline.hpp" 74 75 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 76 77 // turn it on so that the contents of the young list (scan-only / 78 // to-be-collected) are printed at "strategic" points before / during 79 // / after the collection --- this is useful for debugging 80 #define YOUNG_LIST_VERBOSE 0 81 // CURRENT STATUS 82 // This file is under construction. Search for "FIXME". 83 84 // INVARIANTS/NOTES 85 // 86 // All allocation activity covered by the G1CollectedHeap interface is 87 // serialized by acquiring the HeapLock. This happens in mem_allocate 88 // and allocate_new_tlab, which are the "entry" points to the 89 // allocation code from the rest of the JVM. (Note that this does not 90 // apply to TLAB allocation, which is not part of this interface: it 91 // is done by clients of this interface.) 92 93 // Local to this file. 94 95 class RefineCardTableEntryClosure: public CardTableEntryClosure { 96 bool _concurrent; 97 public: 98 RefineCardTableEntryClosure() : _concurrent(true) { } 99 100 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 101 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 102 // This path is executed by the concurrent refine or mutator threads, 103 // concurrently, and so we do not care if card_ptr contains references 104 // that point into the collection set. 105 assert(!oops_into_cset, "should be"); 106 107 if (_concurrent && SuspendibleThreadSet::should_yield()) { 108 // Caller will actually yield. 109 return false; 110 } 111 // Otherwise, we finished successfully; return true. 112 return true; 113 } 114 115 void set_concurrent(bool b) { _concurrent = b; } 116 }; 117 118 119 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 120 private: 121 size_t _num_processed; 122 123 public: 124 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { } 125 126 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 127 *card_ptr = CardTableModRefBS::dirty_card_val(); 128 _num_processed++; 129 return true; 130 } 131 132 size_t num_processed() const { return _num_processed; } 133 }; 134 135 YoungList::YoungList(G1CollectedHeap* g1h) : 136 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 137 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 138 guarantee(check_list_empty(false), "just making sure..."); 139 } 140 141 void YoungList::push_region(HeapRegion *hr) { 142 assert(!hr->is_young(), "should not already be young"); 143 assert(hr->get_next_young_region() == NULL, "cause it should!"); 144 145 hr->set_next_young_region(_head); 146 _head = hr; 147 148 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 149 ++_length; 150 } 151 152 void YoungList::add_survivor_region(HeapRegion* hr) { 153 assert(hr->is_survivor(), "should be flagged as survivor region"); 154 assert(hr->get_next_young_region() == NULL, "cause it should!"); 155 156 hr->set_next_young_region(_survivor_head); 157 if (_survivor_head == NULL) { 158 _survivor_tail = hr; 159 } 160 _survivor_head = hr; 161 ++_survivor_length; 162 } 163 164 void YoungList::empty_list(HeapRegion* list) { 165 while (list != NULL) { 166 HeapRegion* next = list->get_next_young_region(); 167 list->set_next_young_region(NULL); 168 list->uninstall_surv_rate_group(); 169 // This is called before a Full GC and all the non-empty / 170 // non-humongous regions at the end of the Full GC will end up as 171 // old anyway. 172 list->set_old(); 173 list = next; 174 } 175 } 176 177 void YoungList::empty_list() { 178 assert(check_list_well_formed(), "young list should be well formed"); 179 180 empty_list(_head); 181 _head = NULL; 182 _length = 0; 183 184 empty_list(_survivor_head); 185 _survivor_head = NULL; 186 _survivor_tail = NULL; 187 _survivor_length = 0; 188 189 _last_sampled_rs_lengths = 0; 190 191 assert(check_list_empty(false), "just making sure..."); 192 } 193 194 bool YoungList::check_list_well_formed() { 195 bool ret = true; 196 197 uint length = 0; 198 HeapRegion* curr = _head; 199 HeapRegion* last = NULL; 200 while (curr != NULL) { 201 if (!curr->is_young()) { 202 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " 203 "incorrectly tagged (y: %d, surv: %d)", 204 curr->bottom(), curr->end(), 205 curr->is_young(), curr->is_survivor()); 206 ret = false; 207 } 208 ++length; 209 last = curr; 210 curr = curr->get_next_young_region(); 211 } 212 ret = ret && (length == _length); 213 214 if (!ret) { 215 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 216 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 217 length, _length); 218 } 219 220 return ret; 221 } 222 223 bool YoungList::check_list_empty(bool check_sample) { 224 bool ret = true; 225 226 if (_length != 0) { 227 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 228 _length); 229 ret = false; 230 } 231 if (check_sample && _last_sampled_rs_lengths != 0) { 232 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 233 ret = false; 234 } 235 if (_head != NULL) { 236 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 237 ret = false; 238 } 239 if (!ret) { 240 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 241 } 242 243 return ret; 244 } 245 246 void 247 YoungList::rs_length_sampling_init() { 248 _sampled_rs_lengths = 0; 249 _curr = _head; 250 } 251 252 bool 253 YoungList::rs_length_sampling_more() { 254 return _curr != NULL; 255 } 256 257 void 258 YoungList::rs_length_sampling_next() { 259 assert( _curr != NULL, "invariant" ); 260 size_t rs_length = _curr->rem_set()->occupied(); 261 262 _sampled_rs_lengths += rs_length; 263 264 // The current region may not yet have been added to the 265 // incremental collection set (it gets added when it is 266 // retired as the current allocation region). 267 if (_curr->in_collection_set()) { 268 // Update the collection set policy information for this region 269 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 270 } 271 272 _curr = _curr->get_next_young_region(); 273 if (_curr == NULL) { 274 _last_sampled_rs_lengths = _sampled_rs_lengths; 275 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 276 } 277 } 278 279 void 280 YoungList::reset_auxilary_lists() { 281 guarantee( is_empty(), "young list should be empty" ); 282 assert(check_list_well_formed(), "young list should be well formed"); 283 284 // Add survivor regions to SurvRateGroup. 285 _g1h->g1_policy()->note_start_adding_survivor_regions(); 286 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 287 288 int young_index_in_cset = 0; 289 for (HeapRegion* curr = _survivor_head; 290 curr != NULL; 291 curr = curr->get_next_young_region()) { 292 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 293 294 // The region is a non-empty survivor so let's add it to 295 // the incremental collection set for the next evacuation 296 // pause. 297 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 298 young_index_in_cset += 1; 299 } 300 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 301 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 302 303 _head = _survivor_head; 304 _length = _survivor_length; 305 if (_survivor_head != NULL) { 306 assert(_survivor_tail != NULL, "cause it shouldn't be"); 307 assert(_survivor_length > 0, "invariant"); 308 _survivor_tail->set_next_young_region(NULL); 309 } 310 311 // Don't clear the survivor list handles until the start of 312 // the next evacuation pause - we need it in order to re-tag 313 // the survivor regions from this evacuation pause as 'young' 314 // at the start of the next. 315 316 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 317 318 assert(check_list_well_formed(), "young list should be well formed"); 319 } 320 321 void YoungList::print() { 322 HeapRegion* lists[] = {_head, _survivor_head}; 323 const char* names[] = {"YOUNG", "SURVIVOR"}; 324 325 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) { 326 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 327 HeapRegion *curr = lists[list]; 328 if (curr == NULL) 329 gclog_or_tty->print_cr(" empty"); 330 while (curr != NULL) { 331 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d", 332 HR_FORMAT_PARAMS(curr), 333 curr->prev_top_at_mark_start(), 334 curr->next_top_at_mark_start(), 335 curr->age_in_surv_rate_group_cond()); 336 curr = curr->get_next_young_region(); 337 } 338 } 339 340 gclog_or_tty->cr(); 341 } 342 343 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 344 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 345 } 346 347 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 348 // The from card cache is not the memory that is actually committed. So we cannot 349 // take advantage of the zero_filled parameter. 350 reset_from_card_cache(start_idx, num_regions); 351 } 352 353 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 354 { 355 // Claim the right to put the region on the dirty cards region list 356 // by installing a self pointer. 357 HeapRegion* next = hr->get_next_dirty_cards_region(); 358 if (next == NULL) { 359 HeapRegion* res = (HeapRegion*) 360 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 361 NULL); 362 if (res == NULL) { 363 HeapRegion* head; 364 do { 365 // Put the region to the dirty cards region list. 366 head = _dirty_cards_region_list; 367 next = (HeapRegion*) 368 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 369 if (next == head) { 370 assert(hr->get_next_dirty_cards_region() == hr, 371 "hr->get_next_dirty_cards_region() != hr"); 372 if (next == NULL) { 373 // The last region in the list points to itself. 374 hr->set_next_dirty_cards_region(hr); 375 } else { 376 hr->set_next_dirty_cards_region(next); 377 } 378 } 379 } while (next != head); 380 } 381 } 382 } 383 384 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 385 { 386 HeapRegion* head; 387 HeapRegion* hr; 388 do { 389 head = _dirty_cards_region_list; 390 if (head == NULL) { 391 return NULL; 392 } 393 HeapRegion* new_head = head->get_next_dirty_cards_region(); 394 if (head == new_head) { 395 // The last region. 396 new_head = NULL; 397 } 398 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 399 head); 400 } while (hr != head); 401 assert(hr != NULL, "invariant"); 402 hr->set_next_dirty_cards_region(NULL); 403 return hr; 404 } 405 406 // Returns true if the reference points to an object that 407 // can move in an incremental collection. 408 bool G1CollectedHeap::is_scavengable(const void* p) { 409 HeapRegion* hr = heap_region_containing(p); 410 return !hr->is_humongous(); 411 } 412 413 // Private methods. 414 415 HeapRegion* 416 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 417 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 418 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 419 if (!_secondary_free_list.is_empty()) { 420 if (G1ConcRegionFreeingVerbose) { 421 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 422 "secondary_free_list has %u entries", 423 _secondary_free_list.length()); 424 } 425 // It looks as if there are free regions available on the 426 // secondary_free_list. Let's move them to the free_list and try 427 // again to allocate from it. 428 append_secondary_free_list(); 429 430 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 431 "empty we should have moved at least one entry to the free_list"); 432 HeapRegion* res = _hrm.allocate_free_region(is_old); 433 if (G1ConcRegionFreeingVerbose) { 434 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 435 "allocated "HR_FORMAT" from secondary_free_list", 436 HR_FORMAT_PARAMS(res)); 437 } 438 return res; 439 } 440 441 // Wait here until we get notified either when (a) there are no 442 // more free regions coming or (b) some regions have been moved on 443 // the secondary_free_list. 444 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 445 } 446 447 if (G1ConcRegionFreeingVerbose) { 448 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 449 "could not allocate from secondary_free_list"); 450 } 451 return NULL; 452 } 453 454 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 455 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 456 "the only time we use this to allocate a humongous region is " 457 "when we are allocating a single humongous region"); 458 459 HeapRegion* res; 460 if (G1StressConcRegionFreeing) { 461 if (!_secondary_free_list.is_empty()) { 462 if (G1ConcRegionFreeingVerbose) { 463 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 464 "forced to look at the secondary_free_list"); 465 } 466 res = new_region_try_secondary_free_list(is_old); 467 if (res != NULL) { 468 return res; 469 } 470 } 471 } 472 473 res = _hrm.allocate_free_region(is_old); 474 475 if (res == NULL) { 476 if (G1ConcRegionFreeingVerbose) { 477 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 478 "res == NULL, trying the secondary_free_list"); 479 } 480 res = new_region_try_secondary_free_list(is_old); 481 } 482 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 483 // Currently, only attempts to allocate GC alloc regions set 484 // do_expand to true. So, we should only reach here during a 485 // safepoint. If this assumption changes we might have to 486 // reconsider the use of _expand_heap_after_alloc_failure. 487 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 488 489 ergo_verbose1(ErgoHeapSizing, 490 "attempt heap expansion", 491 ergo_format_reason("region allocation request failed") 492 ergo_format_byte("allocation request"), 493 word_size * HeapWordSize); 494 if (expand(word_size * HeapWordSize)) { 495 // Given that expand() succeeded in expanding the heap, and we 496 // always expand the heap by an amount aligned to the heap 497 // region size, the free list should in theory not be empty. 498 // In either case allocate_free_region() will check for NULL. 499 res = _hrm.allocate_free_region(is_old); 500 } else { 501 _expand_heap_after_alloc_failure = false; 502 } 503 } 504 return res; 505 } 506 507 HeapWord* 508 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 509 uint num_regions, 510 size_t word_size, 511 AllocationContext_t context) { 512 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 513 assert(is_humongous(word_size), "word_size should be humongous"); 514 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 515 516 // Index of last region in the series + 1. 517 uint last = first + num_regions; 518 519 // We need to initialize the region(s) we just discovered. This is 520 // a bit tricky given that it can happen concurrently with 521 // refinement threads refining cards on these regions and 522 // potentially wanting to refine the BOT as they are scanning 523 // those cards (this can happen shortly after a cleanup; see CR 524 // 6991377). So we have to set up the region(s) carefully and in 525 // a specific order. 526 527 // The word size sum of all the regions we will allocate. 528 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 529 assert(word_size <= word_size_sum, "sanity"); 530 531 // This will be the "starts humongous" region. 532 HeapRegion* first_hr = region_at(first); 533 // The header of the new object will be placed at the bottom of 534 // the first region. 535 HeapWord* new_obj = first_hr->bottom(); 536 // This will be the new end of the first region in the series that 537 // should also match the end of the last region in the series. 538 HeapWord* new_end = new_obj + word_size_sum; 539 // This will be the new top of the first region that will reflect 540 // this allocation. 541 HeapWord* new_top = new_obj + word_size; 542 543 // First, we need to zero the header of the space that we will be 544 // allocating. When we update top further down, some refinement 545 // threads might try to scan the region. By zeroing the header we 546 // ensure that any thread that will try to scan the region will 547 // come across the zero klass word and bail out. 548 // 549 // NOTE: It would not have been correct to have used 550 // CollectedHeap::fill_with_object() and make the space look like 551 // an int array. The thread that is doing the allocation will 552 // later update the object header to a potentially different array 553 // type and, for a very short period of time, the klass and length 554 // fields will be inconsistent. This could cause a refinement 555 // thread to calculate the object size incorrectly. 556 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 557 558 // We will set up the first region as "starts humongous". This 559 // will also update the BOT covering all the regions to reflect 560 // that there is a single object that starts at the bottom of the 561 // first region. 562 first_hr->set_starts_humongous(new_top, new_end); 563 first_hr->set_allocation_context(context); 564 // Then, if there are any, we will set up the "continues 565 // humongous" regions. 566 HeapRegion* hr = NULL; 567 for (uint i = first + 1; i < last; ++i) { 568 hr = region_at(i); 569 hr->set_continues_humongous(first_hr); 570 hr->set_allocation_context(context); 571 } 572 // If we have "continues humongous" regions (hr != NULL), then the 573 // end of the last one should match new_end. 574 assert(hr == NULL || hr->end() == new_end, "sanity"); 575 576 // Up to this point no concurrent thread would have been able to 577 // do any scanning on any region in this series. All the top 578 // fields still point to bottom, so the intersection between 579 // [bottom,top] and [card_start,card_end] will be empty. Before we 580 // update the top fields, we'll do a storestore to make sure that 581 // no thread sees the update to top before the zeroing of the 582 // object header and the BOT initialization. 583 OrderAccess::storestore(); 584 585 // Now that the BOT and the object header have been initialized, 586 // we can update top of the "starts humongous" region. 587 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 588 "new_top should be in this region"); 589 first_hr->set_top(new_top); 590 if (_hr_printer.is_active()) { 591 HeapWord* bottom = first_hr->bottom(); 592 HeapWord* end = first_hr->orig_end(); 593 if ((first + 1) == last) { 594 // the series has a single humongous region 595 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 596 } else { 597 // the series has more than one humongous regions 598 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 599 } 600 } 601 602 // Now, we will update the top fields of the "continues humongous" 603 // regions. The reason we need to do this is that, otherwise, 604 // these regions would look empty and this will confuse parts of 605 // G1. For example, the code that looks for a consecutive number 606 // of empty regions will consider them empty and try to 607 // re-allocate them. We can extend is_empty() to also include 608 // !is_continues_humongous(), but it is easier to just update the top 609 // fields here. The way we set top for all regions (i.e., top == 610 // end for all regions but the last one, top == new_top for the 611 // last one) is actually used when we will free up the humongous 612 // region in free_humongous_region(). 613 hr = NULL; 614 for (uint i = first + 1; i < last; ++i) { 615 hr = region_at(i); 616 if ((i + 1) == last) { 617 // last continues humongous region 618 assert(hr->bottom() < new_top && new_top <= hr->end(), 619 "new_top should fall on this region"); 620 hr->set_top(new_top); 621 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 622 } else { 623 // not last one 624 assert(new_top > hr->end(), "new_top should be above this region"); 625 hr->set_top(hr->end()); 626 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 627 } 628 } 629 // If we have continues humongous regions (hr != NULL), then the 630 // end of the last one should match new_end and its top should 631 // match new_top. 632 assert(hr == NULL || 633 (hr->end() == new_end && hr->top() == new_top), "sanity"); 634 check_bitmaps("Humongous Region Allocation", first_hr); 635 636 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 637 _allocator->increase_used(first_hr->used()); 638 _humongous_set.add(first_hr); 639 640 return new_obj; 641 } 642 643 // If could fit into free regions w/o expansion, try. 644 // Otherwise, if can expand, do so. 645 // Otherwise, if using ex regions might help, try with ex given back. 646 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 647 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 648 649 verify_region_sets_optional(); 650 651 uint first = G1_NO_HRM_INDEX; 652 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords); 653 654 if (obj_regions == 1) { 655 // Only one region to allocate, try to use a fast path by directly allocating 656 // from the free lists. Do not try to expand here, we will potentially do that 657 // later. 658 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 659 if (hr != NULL) { 660 first = hr->hrm_index(); 661 } 662 } else { 663 // We can't allocate humongous regions spanning more than one region while 664 // cleanupComplete() is running, since some of the regions we find to be 665 // empty might not yet be added to the free list. It is not straightforward 666 // to know in which list they are on so that we can remove them. We only 667 // need to do this if we need to allocate more than one region to satisfy the 668 // current humongous allocation request. If we are only allocating one region 669 // we use the one-region region allocation code (see above), that already 670 // potentially waits for regions from the secondary free list. 671 wait_while_free_regions_coming(); 672 append_secondary_free_list_if_not_empty_with_lock(); 673 674 // Policy: Try only empty regions (i.e. already committed first). Maybe we 675 // are lucky enough to find some. 676 first = _hrm.find_contiguous_only_empty(obj_regions); 677 if (first != G1_NO_HRM_INDEX) { 678 _hrm.allocate_free_regions_starting_at(first, obj_regions); 679 } 680 } 681 682 if (first == G1_NO_HRM_INDEX) { 683 // Policy: We could not find enough regions for the humongous object in the 684 // free list. Look through the heap to find a mix of free and uncommitted regions. 685 // If so, try expansion. 686 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 687 if (first != G1_NO_HRM_INDEX) { 688 // We found something. Make sure these regions are committed, i.e. expand 689 // the heap. Alternatively we could do a defragmentation GC. 690 ergo_verbose1(ErgoHeapSizing, 691 "attempt heap expansion", 692 ergo_format_reason("humongous allocation request failed") 693 ergo_format_byte("allocation request"), 694 word_size * HeapWordSize); 695 696 _hrm.expand_at(first, obj_regions); 697 g1_policy()->record_new_heap_size(num_regions()); 698 699 #ifdef ASSERT 700 for (uint i = first; i < first + obj_regions; ++i) { 701 HeapRegion* hr = region_at(i); 702 assert(hr->is_free(), "sanity"); 703 assert(hr->is_empty(), "sanity"); 704 assert(is_on_master_free_list(hr), "sanity"); 705 } 706 #endif 707 _hrm.allocate_free_regions_starting_at(first, obj_regions); 708 } else { 709 // Policy: Potentially trigger a defragmentation GC. 710 } 711 } 712 713 HeapWord* result = NULL; 714 if (first != G1_NO_HRM_INDEX) { 715 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 716 word_size, context); 717 assert(result != NULL, "it should always return a valid result"); 718 719 // A successful humongous object allocation changes the used space 720 // information of the old generation so we need to recalculate the 721 // sizes and update the jstat counters here. 722 g1mm()->update_sizes(); 723 } 724 725 verify_region_sets_optional(); 726 727 return result; 728 } 729 730 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 731 assert_heap_not_locked_and_not_at_safepoint(); 732 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 733 734 uint dummy_gc_count_before; 735 uint dummy_gclocker_retry_count = 0; 736 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 737 } 738 739 HeapWord* 740 G1CollectedHeap::mem_allocate(size_t word_size, 741 bool* gc_overhead_limit_was_exceeded) { 742 assert_heap_not_locked_and_not_at_safepoint(); 743 744 // Loop until the allocation is satisfied, or unsatisfied after GC. 745 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 746 uint gc_count_before; 747 748 HeapWord* result = NULL; 749 if (!is_humongous(word_size)) { 750 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 751 } else { 752 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 753 } 754 if (result != NULL) { 755 return result; 756 } 757 758 // Create the garbage collection operation... 759 VM_G1CollectForAllocation op(gc_count_before, word_size); 760 op.set_allocation_context(AllocationContext::current()); 761 762 // ...and get the VM thread to execute it. 763 VMThread::execute(&op); 764 765 if (op.prologue_succeeded() && op.pause_succeeded()) { 766 // If the operation was successful we'll return the result even 767 // if it is NULL. If the allocation attempt failed immediately 768 // after a Full GC, it's unlikely we'll be able to allocate now. 769 HeapWord* result = op.result(); 770 if (result != NULL && !is_humongous(word_size)) { 771 // Allocations that take place on VM operations do not do any 772 // card dirtying and we have to do it here. We only have to do 773 // this for non-humongous allocations, though. 774 dirty_young_block(result, word_size); 775 } 776 return result; 777 } else { 778 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 779 return NULL; 780 } 781 assert(op.result() == NULL, 782 "the result should be NULL if the VM op did not succeed"); 783 } 784 785 // Give a warning if we seem to be looping forever. 786 if ((QueuedAllocationWarningCount > 0) && 787 (try_count % QueuedAllocationWarningCount == 0)) { 788 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 789 } 790 } 791 792 ShouldNotReachHere(); 793 return NULL; 794 } 795 796 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 797 AllocationContext_t context, 798 uint* gc_count_before_ret, 799 uint* gclocker_retry_count_ret) { 800 // Make sure you read the note in attempt_allocation_humongous(). 801 802 assert_heap_not_locked_and_not_at_safepoint(); 803 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 804 "be called for humongous allocation requests"); 805 806 // We should only get here after the first-level allocation attempt 807 // (attempt_allocation()) failed to allocate. 808 809 // We will loop until a) we manage to successfully perform the 810 // allocation or b) we successfully schedule a collection which 811 // fails to perform the allocation. b) is the only case when we'll 812 // return NULL. 813 HeapWord* result = NULL; 814 for (int try_count = 1; /* we'll return */; try_count += 1) { 815 bool should_try_gc; 816 uint gc_count_before; 817 818 { 819 MutexLockerEx x(Heap_lock); 820 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, 821 false /* bot_updates */); 822 if (result != NULL) { 823 return result; 824 } 825 826 // If we reach here, attempt_allocation_locked() above failed to 827 // allocate a new region. So the mutator alloc region should be NULL. 828 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here"); 829 830 if (GC_locker::is_active_and_needs_gc()) { 831 if (g1_policy()->can_expand_young_list()) { 832 // No need for an ergo verbose message here, 833 // can_expand_young_list() does this when it returns true. 834 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size, 835 false /* bot_updates */); 836 if (result != NULL) { 837 return result; 838 } 839 } 840 should_try_gc = false; 841 } else { 842 // The GCLocker may not be active but the GCLocker initiated 843 // GC may not yet have been performed (GCLocker::needs_gc() 844 // returns true). In this case we do not try this GC and 845 // wait until the GCLocker initiated GC is performed, and 846 // then retry the allocation. 847 if (GC_locker::needs_gc()) { 848 should_try_gc = false; 849 } else { 850 // Read the GC count while still holding the Heap_lock. 851 gc_count_before = total_collections(); 852 should_try_gc = true; 853 } 854 } 855 } 856 857 if (should_try_gc) { 858 bool succeeded; 859 result = do_collection_pause(word_size, gc_count_before, &succeeded, 860 GCCause::_g1_inc_collection_pause); 861 if (result != NULL) { 862 assert(succeeded, "only way to get back a non-NULL result"); 863 return result; 864 } 865 866 if (succeeded) { 867 // If we get here we successfully scheduled a collection which 868 // failed to allocate. No point in trying to allocate 869 // further. We'll just return NULL. 870 MutexLockerEx x(Heap_lock); 871 *gc_count_before_ret = total_collections(); 872 return NULL; 873 } 874 } else { 875 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 876 MutexLockerEx x(Heap_lock); 877 *gc_count_before_ret = total_collections(); 878 return NULL; 879 } 880 // The GCLocker is either active or the GCLocker initiated 881 // GC has not yet been performed. Stall until it is and 882 // then retry the allocation. 883 GC_locker::stall_until_clear(); 884 (*gclocker_retry_count_ret) += 1; 885 } 886 887 // We can reach here if we were unsuccessful in scheduling a 888 // collection (because another thread beat us to it) or if we were 889 // stalled due to the GC locker. In either can we should retry the 890 // allocation attempt in case another thread successfully 891 // performed a collection and reclaimed enough space. We do the 892 // first attempt (without holding the Heap_lock) here and the 893 // follow-on attempt will be at the start of the next loop 894 // iteration (after taking the Heap_lock). 895 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size, 896 false /* bot_updates */); 897 if (result != NULL) { 898 return result; 899 } 900 901 // Give a warning if we seem to be looping forever. 902 if ((QueuedAllocationWarningCount > 0) && 903 (try_count % QueuedAllocationWarningCount == 0)) { 904 warning("G1CollectedHeap::attempt_allocation_slow() " 905 "retries %d times", try_count); 906 } 907 } 908 909 ShouldNotReachHere(); 910 return NULL; 911 } 912 913 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 914 uint* gc_count_before_ret, 915 uint* gclocker_retry_count_ret) { 916 // The structure of this method has a lot of similarities to 917 // attempt_allocation_slow(). The reason these two were not merged 918 // into a single one is that such a method would require several "if 919 // allocation is not humongous do this, otherwise do that" 920 // conditional paths which would obscure its flow. In fact, an early 921 // version of this code did use a unified method which was harder to 922 // follow and, as a result, it had subtle bugs that were hard to 923 // track down. So keeping these two methods separate allows each to 924 // be more readable. It will be good to keep these two in sync as 925 // much as possible. 926 927 assert_heap_not_locked_and_not_at_safepoint(); 928 assert(is_humongous(word_size), "attempt_allocation_humongous() " 929 "should only be called for humongous allocations"); 930 931 // Humongous objects can exhaust the heap quickly, so we should check if we 932 // need to start a marking cycle at each humongous object allocation. We do 933 // the check before we do the actual allocation. The reason for doing it 934 // before the allocation is that we avoid having to keep track of the newly 935 // allocated memory while we do a GC. 936 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 937 word_size)) { 938 collect(GCCause::_g1_humongous_allocation); 939 } 940 941 // We will loop until a) we manage to successfully perform the 942 // allocation or b) we successfully schedule a collection which 943 // fails to perform the allocation. b) is the only case when we'll 944 // return NULL. 945 HeapWord* result = NULL; 946 for (int try_count = 1; /* we'll return */; try_count += 1) { 947 bool should_try_gc; 948 uint gc_count_before; 949 950 { 951 MutexLockerEx x(Heap_lock); 952 953 // Given that humongous objects are not allocated in young 954 // regions, we'll first try to do the allocation without doing a 955 // collection hoping that there's enough space in the heap. 956 result = humongous_obj_allocate(word_size, AllocationContext::current()); 957 if (result != NULL) { 958 return result; 959 } 960 961 if (GC_locker::is_active_and_needs_gc()) { 962 should_try_gc = false; 963 } else { 964 // The GCLocker may not be active but the GCLocker initiated 965 // GC may not yet have been performed (GCLocker::needs_gc() 966 // returns true). In this case we do not try this GC and 967 // wait until the GCLocker initiated GC is performed, and 968 // then retry the allocation. 969 if (GC_locker::needs_gc()) { 970 should_try_gc = false; 971 } else { 972 // Read the GC count while still holding the Heap_lock. 973 gc_count_before = total_collections(); 974 should_try_gc = true; 975 } 976 } 977 } 978 979 if (should_try_gc) { 980 // If we failed to allocate the humongous object, we should try to 981 // do a collection pause (if we're allowed) in case it reclaims 982 // enough space for the allocation to succeed after the pause. 983 984 bool succeeded; 985 result = do_collection_pause(word_size, gc_count_before, &succeeded, 986 GCCause::_g1_humongous_allocation); 987 if (result != NULL) { 988 assert(succeeded, "only way to get back a non-NULL result"); 989 return result; 990 } 991 992 if (succeeded) { 993 // If we get here we successfully scheduled a collection which 994 // failed to allocate. No point in trying to allocate 995 // further. We'll just return NULL. 996 MutexLockerEx x(Heap_lock); 997 *gc_count_before_ret = total_collections(); 998 return NULL; 999 } 1000 } else { 1001 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1002 MutexLockerEx x(Heap_lock); 1003 *gc_count_before_ret = total_collections(); 1004 return NULL; 1005 } 1006 // The GCLocker is either active or the GCLocker initiated 1007 // GC has not yet been performed. Stall until it is and 1008 // then retry the allocation. 1009 GC_locker::stall_until_clear(); 1010 (*gclocker_retry_count_ret) += 1; 1011 } 1012 1013 // We can reach here if we were unsuccessful in scheduling a 1014 // collection (because another thread beat us to it) or if we were 1015 // stalled due to the GC locker. In either can we should retry the 1016 // allocation attempt in case another thread successfully 1017 // performed a collection and reclaimed enough space. Give a 1018 // warning if we seem to be looping forever. 1019 1020 if ((QueuedAllocationWarningCount > 0) && 1021 (try_count % QueuedAllocationWarningCount == 0)) { 1022 warning("G1CollectedHeap::attempt_allocation_humongous() " 1023 "retries %d times", try_count); 1024 } 1025 } 1026 1027 ShouldNotReachHere(); 1028 return NULL; 1029 } 1030 1031 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1032 AllocationContext_t context, 1033 bool expect_null_mutator_alloc_region) { 1034 assert_at_safepoint(true /* should_be_vm_thread */); 1035 assert(_allocator->mutator_alloc_region(context)->get() == NULL || 1036 !expect_null_mutator_alloc_region, 1037 "the current alloc region was unexpectedly found to be non-NULL"); 1038 1039 if (!is_humongous(word_size)) { 1040 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, 1041 false /* bot_updates */); 1042 } else { 1043 HeapWord* result = humongous_obj_allocate(word_size, context); 1044 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1045 g1_policy()->set_initiate_conc_mark_if_possible(); 1046 } 1047 return result; 1048 } 1049 1050 ShouldNotReachHere(); 1051 } 1052 1053 class PostMCRemSetClearClosure: public HeapRegionClosure { 1054 G1CollectedHeap* _g1h; 1055 ModRefBarrierSet* _mr_bs; 1056 public: 1057 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1058 _g1h(g1h), _mr_bs(mr_bs) {} 1059 1060 bool doHeapRegion(HeapRegion* r) { 1061 HeapRegionRemSet* hrrs = r->rem_set(); 1062 1063 if (r->is_continues_humongous()) { 1064 // We'll assert that the strong code root list and RSet is empty 1065 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1066 assert(hrrs->occupied() == 0, "RSet should be empty"); 1067 return false; 1068 } 1069 1070 _g1h->reset_gc_time_stamps(r); 1071 hrrs->clear(); 1072 // You might think here that we could clear just the cards 1073 // corresponding to the used region. But no: if we leave a dirty card 1074 // in a region we might allocate into, then it would prevent that card 1075 // from being enqueued, and cause it to be missed. 1076 // Re: the performance cost: we shouldn't be doing full GC anyway! 1077 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1078 1079 return false; 1080 } 1081 }; 1082 1083 void G1CollectedHeap::clear_rsets_post_compaction() { 1084 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1085 heap_region_iterate(&rs_clear); 1086 } 1087 1088 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1089 G1CollectedHeap* _g1h; 1090 UpdateRSOopClosure _cl; 1091 uint _worker_i; 1092 public: 1093 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) : 1094 _cl(g1->g1_rem_set(), worker_i), 1095 _worker_i(worker_i), 1096 _g1h(g1) 1097 { } 1098 1099 bool doHeapRegion(HeapRegion* r) { 1100 if (!r->is_continues_humongous()) { 1101 _cl.set_from(r); 1102 r->oop_iterate(&_cl); 1103 } 1104 return false; 1105 } 1106 }; 1107 1108 class ParRebuildRSTask: public AbstractGangTask { 1109 G1CollectedHeap* _g1; 1110 HeapRegionClaimer _hrclaimer; 1111 1112 public: 1113 ParRebuildRSTask(G1CollectedHeap* g1) : 1114 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {} 1115 1116 void work(uint worker_id) { 1117 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1118 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer); 1119 } 1120 }; 1121 1122 class PostCompactionPrinterClosure: public HeapRegionClosure { 1123 private: 1124 G1HRPrinter* _hr_printer; 1125 public: 1126 bool doHeapRegion(HeapRegion* hr) { 1127 assert(!hr->is_young(), "not expecting to find young regions"); 1128 if (hr->is_free()) { 1129 // We only generate output for non-empty regions. 1130 } else if (hr->is_starts_humongous()) { 1131 if (hr->region_num() == 1) { 1132 // single humongous region 1133 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1134 } else { 1135 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1136 } 1137 } else if (hr->is_continues_humongous()) { 1138 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1139 } else if (hr->is_old()) { 1140 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1141 } else { 1142 ShouldNotReachHere(); 1143 } 1144 return false; 1145 } 1146 1147 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1148 : _hr_printer(hr_printer) { } 1149 }; 1150 1151 void G1CollectedHeap::print_hrm_post_compaction() { 1152 PostCompactionPrinterClosure cl(hr_printer()); 1153 heap_region_iterate(&cl); 1154 } 1155 1156 bool G1CollectedHeap::do_collection(bool explicit_gc, 1157 bool clear_all_soft_refs, 1158 size_t word_size) { 1159 assert_at_safepoint(true /* should_be_vm_thread */); 1160 1161 if (GC_locker::check_active_before_gc()) { 1162 return false; 1163 } 1164 1165 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1166 gc_timer->register_gc_start(); 1167 1168 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1169 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1170 1171 SvcGCMarker sgcm(SvcGCMarker::FULL); 1172 ResourceMark rm; 1173 1174 print_heap_before_gc(); 1175 trace_heap_before_gc(gc_tracer); 1176 1177 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1178 1179 verify_region_sets_optional(); 1180 1181 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1182 collector_policy()->should_clear_all_soft_refs(); 1183 1184 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1185 1186 { 1187 IsGCActiveMark x; 1188 1189 // Timing 1190 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); 1191 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1192 1193 { 1194 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id()); 1195 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1196 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1197 1198 g1_policy()->record_full_collection_start(); 1199 1200 // Note: When we have a more flexible GC logging framework that 1201 // allows us to add optional attributes to a GC log record we 1202 // could consider timing and reporting how long we wait in the 1203 // following two methods. 1204 wait_while_free_regions_coming(); 1205 // If we start the compaction before the CM threads finish 1206 // scanning the root regions we might trip them over as we'll 1207 // be moving objects / updating references. So let's wait until 1208 // they are done. By telling them to abort, they should complete 1209 // early. 1210 _cm->root_regions()->abort(); 1211 _cm->root_regions()->wait_until_scan_finished(); 1212 append_secondary_free_list_if_not_empty_with_lock(); 1213 1214 gc_prologue(true); 1215 increment_total_collections(true /* full gc */); 1216 increment_old_marking_cycles_started(); 1217 1218 assert(used() == recalculate_used(), "Should be equal"); 1219 1220 verify_before_gc(); 1221 1222 check_bitmaps("Full GC Start"); 1223 pre_full_gc_dump(gc_timer); 1224 1225 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1226 1227 // Disable discovery and empty the discovered lists 1228 // for the CM ref processor. 1229 ref_processor_cm()->disable_discovery(); 1230 ref_processor_cm()->abandon_partial_discovery(); 1231 ref_processor_cm()->verify_no_references_recorded(); 1232 1233 // Abandon current iterations of concurrent marking and concurrent 1234 // refinement, if any are in progress. We have to do this before 1235 // wait_until_scan_finished() below. 1236 concurrent_mark()->abort(); 1237 1238 // Make sure we'll choose a new allocation region afterwards. 1239 _allocator->release_mutator_alloc_region(); 1240 _allocator->abandon_gc_alloc_regions(); 1241 g1_rem_set()->cleanupHRRS(); 1242 1243 // We should call this after we retire any currently active alloc 1244 // regions so that all the ALLOC / RETIRE events are generated 1245 // before the start GC event. 1246 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1247 1248 // We may have added regions to the current incremental collection 1249 // set between the last GC or pause and now. We need to clear the 1250 // incremental collection set and then start rebuilding it afresh 1251 // after this full GC. 1252 abandon_collection_set(g1_policy()->inc_cset_head()); 1253 g1_policy()->clear_incremental_cset(); 1254 g1_policy()->stop_incremental_cset_building(); 1255 1256 tear_down_region_sets(false /* free_list_only */); 1257 g1_policy()->set_gcs_are_young(true); 1258 1259 // See the comments in g1CollectedHeap.hpp and 1260 // G1CollectedHeap::ref_processing_init() about 1261 // how reference processing currently works in G1. 1262 1263 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1264 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1265 1266 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1267 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1268 1269 ref_processor_stw()->enable_discovery(); 1270 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1271 1272 // Do collection work 1273 { 1274 HandleMark hm; // Discard invalid handles created during gc 1275 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1276 } 1277 1278 assert(num_free_regions() == 0, "we should not have added any free regions"); 1279 rebuild_region_sets(false /* free_list_only */); 1280 1281 // Enqueue any discovered reference objects that have 1282 // not been removed from the discovered lists. 1283 ref_processor_stw()->enqueue_discovered_references(); 1284 1285 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1286 1287 MemoryService::track_memory_usage(); 1288 1289 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1290 ref_processor_stw()->verify_no_references_recorded(); 1291 1292 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1293 ClassLoaderDataGraph::purge(); 1294 MetaspaceAux::verify_metrics(); 1295 1296 // Note: since we've just done a full GC, concurrent 1297 // marking is no longer active. Therefore we need not 1298 // re-enable reference discovery for the CM ref processor. 1299 // That will be done at the start of the next marking cycle. 1300 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1301 ref_processor_cm()->verify_no_references_recorded(); 1302 1303 reset_gc_time_stamp(); 1304 // Since everything potentially moved, we will clear all remembered 1305 // sets, and clear all cards. Later we will rebuild remembered 1306 // sets. We will also reset the GC time stamps of the regions. 1307 clear_rsets_post_compaction(); 1308 check_gc_time_stamps(); 1309 1310 // Resize the heap if necessary. 1311 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1312 1313 if (_hr_printer.is_active()) { 1314 // We should do this after we potentially resize the heap so 1315 // that all the COMMIT / UNCOMMIT events are generated before 1316 // the end GC event. 1317 1318 print_hrm_post_compaction(); 1319 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1320 } 1321 1322 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1323 if (hot_card_cache->use_cache()) { 1324 hot_card_cache->reset_card_counts(); 1325 hot_card_cache->reset_hot_cache(); 1326 } 1327 1328 // Rebuild remembered sets of all regions. 1329 uint n_workers = 1330 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1331 workers()->active_workers(), 1332 Threads::number_of_non_daemon_threads()); 1333 assert(UseDynamicNumberOfGCThreads || 1334 n_workers == workers()->total_workers(), 1335 "If not dynamic should be using all the workers"); 1336 workers()->set_active_workers(n_workers); 1337 // Set parallel threads in the heap (_n_par_threads) only 1338 // before a parallel phase and always reset it to 0 after 1339 // the phase so that the number of parallel threads does 1340 // no get carried forward to a serial phase where there 1341 // may be code that is "possibly_parallel". 1342 set_par_threads(n_workers); 1343 1344 ParRebuildRSTask rebuild_rs_task(this); 1345 assert(UseDynamicNumberOfGCThreads || 1346 workers()->active_workers() == workers()->total_workers(), 1347 "Unless dynamic should use total workers"); 1348 // Use the most recent number of active workers 1349 assert(workers()->active_workers() > 0, 1350 "Active workers not properly set"); 1351 set_par_threads(workers()->active_workers()); 1352 workers()->run_task(&rebuild_rs_task); 1353 set_par_threads(0); 1354 1355 // Rebuild the strong code root lists for each region 1356 rebuild_strong_code_roots(); 1357 1358 if (true) { // FIXME 1359 MetaspaceGC::compute_new_size(); 1360 } 1361 1362 #ifdef TRACESPINNING 1363 ParallelTaskTerminator::print_termination_counts(); 1364 #endif 1365 1366 // Discard all rset updates 1367 JavaThread::dirty_card_queue_set().abandon_logs(); 1368 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1369 1370 _young_list->reset_sampled_info(); 1371 // At this point there should be no regions in the 1372 // entire heap tagged as young. 1373 assert(check_young_list_empty(true /* check_heap */), 1374 "young list should be empty at this point"); 1375 1376 // Update the number of full collections that have been completed. 1377 increment_old_marking_cycles_completed(false /* concurrent */); 1378 1379 _hrm.verify_optional(); 1380 verify_region_sets_optional(); 1381 1382 verify_after_gc(); 1383 1384 // Clear the previous marking bitmap, if needed for bitmap verification. 1385 // Note we cannot do this when we clear the next marking bitmap in 1386 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1387 // objects marked during a full GC against the previous bitmap. 1388 // But we need to clear it before calling check_bitmaps below since 1389 // the full GC has compacted objects and updated TAMS but not updated 1390 // the prev bitmap. 1391 if (G1VerifyBitmaps) { 1392 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1393 } 1394 check_bitmaps("Full GC End"); 1395 1396 // Start a new incremental collection set for the next pause 1397 assert(g1_policy()->collection_set() == NULL, "must be"); 1398 g1_policy()->start_incremental_cset_building(); 1399 1400 clear_cset_fast_test(); 1401 1402 _allocator->init_mutator_alloc_region(); 1403 1404 g1_policy()->record_full_collection_end(); 1405 1406 if (G1Log::fine()) { 1407 g1_policy()->print_heap_transition(); 1408 } 1409 1410 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1411 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1412 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1413 // before any GC notifications are raised. 1414 g1mm()->update_sizes(); 1415 1416 gc_epilogue(true); 1417 } 1418 1419 if (G1Log::finer()) { 1420 g1_policy()->print_detailed_heap_transition(true /* full */); 1421 } 1422 1423 print_heap_after_gc(); 1424 trace_heap_after_gc(gc_tracer); 1425 1426 post_full_gc_dump(gc_timer); 1427 1428 gc_timer->register_gc_end(); 1429 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1430 } 1431 1432 return true; 1433 } 1434 1435 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1436 // do_collection() will return whether it succeeded in performing 1437 // the GC. Currently, there is no facility on the 1438 // do_full_collection() API to notify the caller than the collection 1439 // did not succeed (e.g., because it was locked out by the GC 1440 // locker). So, right now, we'll ignore the return value. 1441 bool dummy = do_collection(true, /* explicit_gc */ 1442 clear_all_soft_refs, 1443 0 /* word_size */); 1444 } 1445 1446 // This code is mostly copied from TenuredGeneration. 1447 void 1448 G1CollectedHeap:: 1449 resize_if_necessary_after_full_collection(size_t word_size) { 1450 // Include the current allocation, if any, and bytes that will be 1451 // pre-allocated to support collections, as "used". 1452 const size_t used_after_gc = used(); 1453 const size_t capacity_after_gc = capacity(); 1454 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1455 1456 // This is enforced in arguments.cpp. 1457 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1458 "otherwise the code below doesn't make sense"); 1459 1460 // We don't have floating point command-line arguments 1461 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1462 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1463 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1464 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1465 1466 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1467 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1468 1469 // We have to be careful here as these two calculations can overflow 1470 // 32-bit size_t's. 1471 double used_after_gc_d = (double) used_after_gc; 1472 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1473 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1474 1475 // Let's make sure that they are both under the max heap size, which 1476 // by default will make them fit into a size_t. 1477 double desired_capacity_upper_bound = (double) max_heap_size; 1478 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1479 desired_capacity_upper_bound); 1480 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1481 desired_capacity_upper_bound); 1482 1483 // We can now safely turn them into size_t's. 1484 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1485 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1486 1487 // This assert only makes sense here, before we adjust them 1488 // with respect to the min and max heap size. 1489 assert(minimum_desired_capacity <= maximum_desired_capacity, 1490 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1491 "maximum_desired_capacity = "SIZE_FORMAT, 1492 minimum_desired_capacity, maximum_desired_capacity)); 1493 1494 // Should not be greater than the heap max size. No need to adjust 1495 // it with respect to the heap min size as it's a lower bound (i.e., 1496 // we'll try to make the capacity larger than it, not smaller). 1497 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1498 // Should not be less than the heap min size. No need to adjust it 1499 // with respect to the heap max size as it's an upper bound (i.e., 1500 // we'll try to make the capacity smaller than it, not greater). 1501 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1502 1503 if (capacity_after_gc < minimum_desired_capacity) { 1504 // Don't expand unless it's significant 1505 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1506 ergo_verbose4(ErgoHeapSizing, 1507 "attempt heap expansion", 1508 ergo_format_reason("capacity lower than " 1509 "min desired capacity after Full GC") 1510 ergo_format_byte("capacity") 1511 ergo_format_byte("occupancy") 1512 ergo_format_byte_perc("min desired capacity"), 1513 capacity_after_gc, used_after_gc, 1514 minimum_desired_capacity, (double) MinHeapFreeRatio); 1515 expand(expand_bytes); 1516 1517 // No expansion, now see if we want to shrink 1518 } else if (capacity_after_gc > maximum_desired_capacity) { 1519 // Capacity too large, compute shrinking size 1520 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1521 ergo_verbose4(ErgoHeapSizing, 1522 "attempt heap shrinking", 1523 ergo_format_reason("capacity higher than " 1524 "max desired capacity after Full GC") 1525 ergo_format_byte("capacity") 1526 ergo_format_byte("occupancy") 1527 ergo_format_byte_perc("max desired capacity"), 1528 capacity_after_gc, used_after_gc, 1529 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1530 shrink(shrink_bytes); 1531 } 1532 } 1533 1534 1535 HeapWord* 1536 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1537 AllocationContext_t context, 1538 bool* succeeded) { 1539 assert_at_safepoint(true /* should_be_vm_thread */); 1540 1541 *succeeded = true; 1542 // Let's attempt the allocation first. 1543 HeapWord* result = 1544 attempt_allocation_at_safepoint(word_size, 1545 context, 1546 false /* expect_null_mutator_alloc_region */); 1547 if (result != NULL) { 1548 assert(*succeeded, "sanity"); 1549 return result; 1550 } 1551 1552 // In a G1 heap, we're supposed to keep allocation from failing by 1553 // incremental pauses. Therefore, at least for now, we'll favor 1554 // expansion over collection. (This might change in the future if we can 1555 // do something smarter than full collection to satisfy a failed alloc.) 1556 result = expand_and_allocate(word_size, context); 1557 if (result != NULL) { 1558 assert(*succeeded, "sanity"); 1559 return result; 1560 } 1561 1562 // Expansion didn't work, we'll try to do a Full GC. 1563 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1564 false, /* clear_all_soft_refs */ 1565 word_size); 1566 if (!gc_succeeded) { 1567 *succeeded = false; 1568 return NULL; 1569 } 1570 1571 // Retry the allocation 1572 result = attempt_allocation_at_safepoint(word_size, 1573 context, 1574 true /* expect_null_mutator_alloc_region */); 1575 if (result != NULL) { 1576 assert(*succeeded, "sanity"); 1577 return result; 1578 } 1579 1580 // Then, try a Full GC that will collect all soft references. 1581 gc_succeeded = do_collection(false, /* explicit_gc */ 1582 true, /* clear_all_soft_refs */ 1583 word_size); 1584 if (!gc_succeeded) { 1585 *succeeded = false; 1586 return NULL; 1587 } 1588 1589 // Retry the allocation once more 1590 result = attempt_allocation_at_safepoint(word_size, 1591 context, 1592 true /* expect_null_mutator_alloc_region */); 1593 if (result != NULL) { 1594 assert(*succeeded, "sanity"); 1595 return result; 1596 } 1597 1598 assert(!collector_policy()->should_clear_all_soft_refs(), 1599 "Flag should have been handled and cleared prior to this point"); 1600 1601 // What else? We might try synchronous finalization later. If the total 1602 // space available is large enough for the allocation, then a more 1603 // complete compaction phase than we've tried so far might be 1604 // appropriate. 1605 assert(*succeeded, "sanity"); 1606 return NULL; 1607 } 1608 1609 // Attempting to expand the heap sufficiently 1610 // to support an allocation of the given "word_size". If 1611 // successful, perform the allocation and return the address of the 1612 // allocated block, or else "NULL". 1613 1614 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1615 assert_at_safepoint(true /* should_be_vm_thread */); 1616 1617 verify_region_sets_optional(); 1618 1619 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1620 ergo_verbose1(ErgoHeapSizing, 1621 "attempt heap expansion", 1622 ergo_format_reason("allocation request failed") 1623 ergo_format_byte("allocation request"), 1624 word_size * HeapWordSize); 1625 if (expand(expand_bytes)) { 1626 _hrm.verify_optional(); 1627 verify_region_sets_optional(); 1628 return attempt_allocation_at_safepoint(word_size, 1629 context, 1630 false /* expect_null_mutator_alloc_region */); 1631 } 1632 return NULL; 1633 } 1634 1635 bool G1CollectedHeap::expand(size_t expand_bytes) { 1636 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1637 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1638 HeapRegion::GrainBytes); 1639 ergo_verbose2(ErgoHeapSizing, 1640 "expand the heap", 1641 ergo_format_byte("requested expansion amount") 1642 ergo_format_byte("attempted expansion amount"), 1643 expand_bytes, aligned_expand_bytes); 1644 1645 if (is_maximal_no_gc()) { 1646 ergo_verbose0(ErgoHeapSizing, 1647 "did not expand the heap", 1648 ergo_format_reason("heap already fully expanded")); 1649 return false; 1650 } 1651 1652 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1653 assert(regions_to_expand > 0, "Must expand by at least one region"); 1654 1655 uint expanded_by = _hrm.expand_by(regions_to_expand); 1656 1657 if (expanded_by > 0) { 1658 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1659 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1660 g1_policy()->record_new_heap_size(num_regions()); 1661 } else { 1662 ergo_verbose0(ErgoHeapSizing, 1663 "did not expand the heap", 1664 ergo_format_reason("heap expansion operation failed")); 1665 // The expansion of the virtual storage space was unsuccessful. 1666 // Let's see if it was because we ran out of swap. 1667 if (G1ExitOnExpansionFailure && 1668 _hrm.available() >= regions_to_expand) { 1669 // We had head room... 1670 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1671 } 1672 } 1673 return regions_to_expand > 0; 1674 } 1675 1676 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1677 size_t aligned_shrink_bytes = 1678 ReservedSpace::page_align_size_down(shrink_bytes); 1679 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1680 HeapRegion::GrainBytes); 1681 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1682 1683 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1684 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1685 1686 ergo_verbose3(ErgoHeapSizing, 1687 "shrink the heap", 1688 ergo_format_byte("requested shrinking amount") 1689 ergo_format_byte("aligned shrinking amount") 1690 ergo_format_byte("attempted shrinking amount"), 1691 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1692 if (num_regions_removed > 0) { 1693 g1_policy()->record_new_heap_size(num_regions()); 1694 } else { 1695 ergo_verbose0(ErgoHeapSizing, 1696 "did not shrink the heap", 1697 ergo_format_reason("heap shrinking operation failed")); 1698 } 1699 } 1700 1701 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1702 verify_region_sets_optional(); 1703 1704 // We should only reach here at the end of a Full GC which means we 1705 // should not not be holding to any GC alloc regions. The method 1706 // below will make sure of that and do any remaining clean up. 1707 _allocator->abandon_gc_alloc_regions(); 1708 1709 // Instead of tearing down / rebuilding the free lists here, we 1710 // could instead use the remove_all_pending() method on free_list to 1711 // remove only the ones that we need to remove. 1712 tear_down_region_sets(true /* free_list_only */); 1713 shrink_helper(shrink_bytes); 1714 rebuild_region_sets(true /* free_list_only */); 1715 1716 _hrm.verify_optional(); 1717 verify_region_sets_optional(); 1718 } 1719 1720 // Public methods. 1721 1722 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1723 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1724 #endif // _MSC_VER 1725 1726 1727 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1728 CollectedHeap(), 1729 _g1_policy(policy_), 1730 _dirty_card_queue_set(false), 1731 _into_cset_dirty_card_queue_set(false), 1732 _is_alive_closure_cm(this), 1733 _is_alive_closure_stw(this), 1734 _ref_processor_cm(NULL), 1735 _ref_processor_stw(NULL), 1736 _bot_shared(NULL), 1737 _evac_failure_scan_stack(NULL), 1738 _mark_in_progress(false), 1739 _cg1r(NULL), 1740 _g1mm(NULL), 1741 _refine_cte_cl(NULL), 1742 _full_collection(false), 1743 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1744 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1745 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1746 _humongous_reclaim_candidates(), 1747 _has_humongous_reclaim_candidates(false), 1748 _free_regions_coming(false), 1749 _young_list(new YoungList(this)), 1750 _gc_time_stamp(0), 1751 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1752 _old_plab_stats(OldPLABSize, PLABWeight), 1753 _expand_heap_after_alloc_failure(true), 1754 _surviving_young_words(NULL), 1755 _old_marking_cycles_started(0), 1756 _old_marking_cycles_completed(0), 1757 _concurrent_cycle_started(false), 1758 _heap_summary_sent(false), 1759 _in_cset_fast_test(), 1760 _dirty_cards_region_list(NULL), 1761 _worker_cset_start_region(NULL), 1762 _worker_cset_start_region_time_stamp(NULL), 1763 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1764 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1765 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1766 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1767 1768 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads, 1769 /* are_GC_task_threads */true, 1770 /* are_ConcurrentGC_threads */false); 1771 _workers->initialize_workers(); 1772 1773 _allocator = G1Allocator::create_allocator(this); 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 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1801 size_t size, 1802 size_t translation_factor) { 1803 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1804 // Allocate a new reserved space, preferring to use large pages. 1805 ReservedSpace rs(size, preferred_page_size); 1806 G1RegionToSpaceMapper* result = 1807 G1RegionToSpaceMapper::create_mapper(rs, 1808 size, 1809 rs.alignment(), 1810 HeapRegion::GrainBytes, 1811 translation_factor, 1812 mtGC); 1813 if (TracePageSizes) { 1814 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT, 1815 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size); 1816 } 1817 return result; 1818 } 1819 1820 jint G1CollectedHeap::initialize() { 1821 CollectedHeap::pre_initialize(); 1822 os::enable_vtime(); 1823 1824 G1Log::init(); 1825 1826 // Necessary to satisfy locking discipline assertions. 1827 1828 MutexLocker x(Heap_lock); 1829 1830 // We have to initialize the printer before committing the heap, as 1831 // it will be used then. 1832 _hr_printer.set_active(G1PrintHeapRegions); 1833 1834 // While there are no constraints in the GC code that HeapWordSize 1835 // be any particular value, there are multiple other areas in the 1836 // system which believe this to be true (e.g. oop->object_size in some 1837 // cases incorrectly returns the size in wordSize units rather than 1838 // HeapWordSize). 1839 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1840 1841 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1842 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1843 size_t heap_alignment = collector_policy()->heap_alignment(); 1844 1845 // Ensure that the sizes are properly aligned. 1846 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1847 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1848 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1849 1850 _refine_cte_cl = new RefineCardTableEntryClosure(); 1851 1852 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl); 1853 1854 // Reserve the maximum. 1855 1856 // When compressed oops are enabled, the preferred heap base 1857 // is calculated by subtracting the requested size from the 1858 // 32Gb boundary and using the result as the base address for 1859 // heap reservation. If the requested size is not aligned to 1860 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1861 // into the ReservedHeapSpace constructor) then the actual 1862 // base of the reserved heap may end up differing from the 1863 // address that was requested (i.e. the preferred heap base). 1864 // If this happens then we could end up using a non-optimal 1865 // compressed oops mode. 1866 1867 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1868 heap_alignment); 1869 1870 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1871 1872 // Create the barrier set for the entire reserved region. 1873 G1SATBCardTableLoggingModRefBS* bs 1874 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 1875 bs->initialize(); 1876 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 1877 set_barrier_set(bs); 1878 1879 // Also create a G1 rem set. 1880 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 1881 1882 // Carve out the G1 part of the heap. 1883 1884 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1885 G1RegionToSpaceMapper* heap_storage = 1886 G1RegionToSpaceMapper::create_mapper(g1_rs, 1887 g1_rs.size(), 1888 UseLargePages ? os::large_page_size() : os::vm_page_size(), 1889 HeapRegion::GrainBytes, 1890 1, 1891 mtJavaHeap); 1892 heap_storage->set_mapping_changed_listener(&_listener); 1893 1894 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1895 G1RegionToSpaceMapper* bot_storage = 1896 create_aux_memory_mapper("Block offset table", 1897 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize), 1898 G1BlockOffsetSharedArray::N_bytes); 1899 1900 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 1901 G1RegionToSpaceMapper* cardtable_storage = 1902 create_aux_memory_mapper("Card table", 1903 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize), 1904 G1BlockOffsetSharedArray::N_bytes); 1905 1906 G1RegionToSpaceMapper* card_counts_storage = 1907 create_aux_memory_mapper("Card counts table", 1908 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize), 1909 G1BlockOffsetSharedArray::N_bytes); 1910 1911 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); 1912 G1RegionToSpaceMapper* prev_bitmap_storage = 1913 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::mark_distance()); 1914 G1RegionToSpaceMapper* next_bitmap_storage = 1915 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::mark_distance()); 1916 1917 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1918 g1_barrier_set()->initialize(cardtable_storage); 1919 // Do later initialization work for concurrent refinement. 1920 _cg1r->init(card_counts_storage); 1921 1922 // 6843694 - ensure that the maximum region index can fit 1923 // in the remembered set structures. 1924 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1925 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1926 1927 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1928 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1929 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1930 "too many cards per region"); 1931 1932 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1933 1934 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage); 1935 1936 { 1937 HeapWord* start = _hrm.reserved().start(); 1938 HeapWord* end = _hrm.reserved().end(); 1939 size_t granularity = HeapRegion::GrainBytes; 1940 1941 _in_cset_fast_test.initialize(start, end, granularity); 1942 _humongous_reclaim_candidates.initialize(start, end, granularity); 1943 } 1944 1945 // Create the ConcurrentMark data structure and thread. 1946 // (Must do this late, so that "max_regions" is defined.) 1947 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1948 if (_cm == NULL || !_cm->completed_initialization()) { 1949 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 1950 return JNI_ENOMEM; 1951 } 1952 _cmThread = _cm->cmThread(); 1953 1954 // Initialize the from_card cache structure of HeapRegionRemSet. 1955 HeapRegionRemSet::init_heap(max_regions()); 1956 1957 // Now expand into the initial heap size. 1958 if (!expand(init_byte_size)) { 1959 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1960 return JNI_ENOMEM; 1961 } 1962 1963 // Perform any initialization actions delegated to the policy. 1964 g1_policy()->init(); 1965 1966 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 1967 SATB_Q_FL_lock, 1968 G1SATBProcessCompletedThreshold, 1969 Shared_SATB_Q_lock); 1970 1971 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 1972 DirtyCardQ_CBL_mon, 1973 DirtyCardQ_FL_lock, 1974 concurrent_g1_refine()->yellow_zone(), 1975 concurrent_g1_refine()->red_zone(), 1976 Shared_DirtyCardQ_lock); 1977 1978 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 1979 DirtyCardQ_CBL_mon, 1980 DirtyCardQ_FL_lock, 1981 -1, // never trigger processing 1982 -1, // no limit on length 1983 Shared_DirtyCardQ_lock, 1984 &JavaThread::dirty_card_queue_set()); 1985 1986 // Initialize the card queue set used to hold cards containing 1987 // references into the collection set. 1988 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 1989 DirtyCardQ_CBL_mon, 1990 DirtyCardQ_FL_lock, 1991 -1, // never trigger processing 1992 -1, // no limit on length 1993 Shared_DirtyCardQ_lock, 1994 &JavaThread::dirty_card_queue_set()); 1995 1996 // Here we allocate the dummy HeapRegion that is required by the 1997 // G1AllocRegion class. 1998 HeapRegion* dummy_region = _hrm.get_dummy_region(); 1999 2000 // We'll re-use the same region whether the alloc region will 2001 // require BOT updates or not and, if it doesn't, then a non-young 2002 // region will complain that it cannot support allocations without 2003 // BOT updates. So we'll tag the dummy region as eden to avoid that. 2004 dummy_region->set_eden(); 2005 // Make sure it's full. 2006 dummy_region->set_top(dummy_region->end()); 2007 G1AllocRegion::setup(this, dummy_region); 2008 2009 _allocator->init_mutator_alloc_region(); 2010 2011 // Do create of the monitoring and management support so that 2012 // values in the heap have been properly initialized. 2013 _g1mm = new G1MonitoringSupport(this); 2014 2015 G1StringDedup::initialize(); 2016 2017 return JNI_OK; 2018 } 2019 2020 void G1CollectedHeap::stop() { 2021 // Stop all concurrent threads. We do this to make sure these threads 2022 // do not continue to execute and access resources (e.g. gclog_or_tty) 2023 // that are destroyed during shutdown. 2024 _cg1r->stop(); 2025 _cmThread->stop(); 2026 if (G1StringDedup::is_enabled()) { 2027 G1StringDedup::stop(); 2028 } 2029 } 2030 2031 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2032 return HeapRegion::max_region_size(); 2033 } 2034 2035 void G1CollectedHeap::post_initialize() { 2036 CollectedHeap::post_initialize(); 2037 ref_processing_init(); 2038 } 2039 2040 void G1CollectedHeap::ref_processing_init() { 2041 // Reference processing in G1 currently works as follows: 2042 // 2043 // * There are two reference processor instances. One is 2044 // used to record and process discovered references 2045 // during concurrent marking; the other is used to 2046 // record and process references during STW pauses 2047 // (both full and incremental). 2048 // * Both ref processors need to 'span' the entire heap as 2049 // the regions in the collection set may be dotted around. 2050 // 2051 // * For the concurrent marking ref processor: 2052 // * Reference discovery is enabled at initial marking. 2053 // * Reference discovery is disabled and the discovered 2054 // references processed etc during remarking. 2055 // * Reference discovery is MT (see below). 2056 // * Reference discovery requires a barrier (see below). 2057 // * Reference processing may or may not be MT 2058 // (depending on the value of ParallelRefProcEnabled 2059 // and ParallelGCThreads). 2060 // * A full GC disables reference discovery by the CM 2061 // ref processor and abandons any entries on it's 2062 // discovered lists. 2063 // 2064 // * For the STW processor: 2065 // * Non MT discovery is enabled at the start of a full GC. 2066 // * Processing and enqueueing during a full GC is non-MT. 2067 // * During a full GC, references are processed after marking. 2068 // 2069 // * Discovery (may or may not be MT) is enabled at the start 2070 // of an incremental evacuation pause. 2071 // * References are processed near the end of a STW evacuation pause. 2072 // * For both types of GC: 2073 // * Discovery is atomic - i.e. not concurrent. 2074 // * Reference discovery will not need a barrier. 2075 2076 MemRegion mr = reserved_region(); 2077 2078 // Concurrent Mark ref processor 2079 _ref_processor_cm = 2080 new ReferenceProcessor(mr, // span 2081 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2082 // mt processing 2083 (int) ParallelGCThreads, 2084 // degree of mt processing 2085 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2086 // mt discovery 2087 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2088 // degree of mt discovery 2089 false, 2090 // Reference discovery is not atomic 2091 &_is_alive_closure_cm); 2092 // is alive closure 2093 // (for efficiency/performance) 2094 2095 // STW ref processor 2096 _ref_processor_stw = 2097 new ReferenceProcessor(mr, // span 2098 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2099 // mt processing 2100 MAX2((int)ParallelGCThreads, 1), 2101 // degree of mt processing 2102 (ParallelGCThreads > 1), 2103 // mt discovery 2104 MAX2((int)ParallelGCThreads, 1), 2105 // degree of mt discovery 2106 true, 2107 // Reference discovery is atomic 2108 &_is_alive_closure_stw); 2109 // is alive closure 2110 // (for efficiency/performance) 2111 } 2112 2113 size_t G1CollectedHeap::capacity() const { 2114 return _hrm.length() * HeapRegion::GrainBytes; 2115 } 2116 2117 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2118 assert(!hr->is_continues_humongous(), "pre-condition"); 2119 hr->reset_gc_time_stamp(); 2120 if (hr->is_starts_humongous()) { 2121 uint first_index = hr->hrm_index() + 1; 2122 uint last_index = hr->last_hc_index(); 2123 for (uint i = first_index; i < last_index; i += 1) { 2124 HeapRegion* chr = region_at(i); 2125 assert(chr->is_continues_humongous(), "sanity"); 2126 chr->reset_gc_time_stamp(); 2127 } 2128 } 2129 } 2130 2131 #ifndef PRODUCT 2132 2133 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2134 private: 2135 unsigned _gc_time_stamp; 2136 bool _failures; 2137 2138 public: 2139 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2140 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2141 2142 virtual bool doHeapRegion(HeapRegion* hr) { 2143 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2144 if (_gc_time_stamp != region_gc_time_stamp) { 2145 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2146 "expected %d", HR_FORMAT_PARAMS(hr), 2147 region_gc_time_stamp, _gc_time_stamp); 2148 _failures = true; 2149 } 2150 return false; 2151 } 2152 2153 bool failures() { return _failures; } 2154 }; 2155 2156 void G1CollectedHeap::check_gc_time_stamps() { 2157 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2158 heap_region_iterate(&cl); 2159 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2160 } 2161 #endif // PRODUCT 2162 2163 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2164 DirtyCardQueue* into_cset_dcq, 2165 bool concurrent, 2166 uint worker_i) { 2167 // Clean cards in the hot card cache 2168 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2169 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2170 2171 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2172 size_t n_completed_buffers = 0; 2173 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2174 n_completed_buffers++; 2175 } 2176 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 2177 dcqs.clear_n_completed_buffers(); 2178 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2179 } 2180 2181 2182 // Computes the sum of the storage used by the various regions. 2183 size_t G1CollectedHeap::used() const { 2184 return _allocator->used(); 2185 } 2186 2187 size_t G1CollectedHeap::used_unlocked() const { 2188 return _allocator->used_unlocked(); 2189 } 2190 2191 class SumUsedClosure: public HeapRegionClosure { 2192 size_t _used; 2193 public: 2194 SumUsedClosure() : _used(0) {} 2195 bool doHeapRegion(HeapRegion* r) { 2196 if (!r->is_continues_humongous()) { 2197 _used += r->used(); 2198 } 2199 return false; 2200 } 2201 size_t result() { return _used; } 2202 }; 2203 2204 size_t G1CollectedHeap::recalculate_used() const { 2205 double recalculate_used_start = os::elapsedTime(); 2206 2207 SumUsedClosure blk; 2208 heap_region_iterate(&blk); 2209 2210 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2211 return blk.result(); 2212 } 2213 2214 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2215 switch (cause) { 2216 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2217 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2218 case GCCause::_g1_humongous_allocation: return true; 2219 case GCCause::_update_allocation_context_stats_inc: return true; 2220 case GCCause::_wb_conc_mark: return true; 2221 default: return false; 2222 } 2223 } 2224 2225 #ifndef PRODUCT 2226 void G1CollectedHeap::allocate_dummy_regions() { 2227 // Let's fill up most of the region 2228 size_t word_size = HeapRegion::GrainWords - 1024; 2229 // And as a result the region we'll allocate will be humongous. 2230 guarantee(is_humongous(word_size), "sanity"); 2231 2232 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2233 // Let's use the existing mechanism for the allocation 2234 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2235 AllocationContext::system()); 2236 if (dummy_obj != NULL) { 2237 MemRegion mr(dummy_obj, word_size); 2238 CollectedHeap::fill_with_object(mr); 2239 } else { 2240 // If we can't allocate once, we probably cannot allocate 2241 // again. Let's get out of the loop. 2242 break; 2243 } 2244 } 2245 } 2246 #endif // !PRODUCT 2247 2248 void G1CollectedHeap::increment_old_marking_cycles_started() { 2249 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2250 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2251 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2252 _old_marking_cycles_started, _old_marking_cycles_completed)); 2253 2254 _old_marking_cycles_started++; 2255 } 2256 2257 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2258 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2259 2260 // We assume that if concurrent == true, then the caller is a 2261 // concurrent thread that was joined the Suspendible Thread 2262 // Set. If there's ever a cheap way to check this, we should add an 2263 // assert here. 2264 2265 // Given that this method is called at the end of a Full GC or of a 2266 // concurrent cycle, and those can be nested (i.e., a Full GC can 2267 // interrupt a concurrent cycle), the number of full collections 2268 // completed should be either one (in the case where there was no 2269 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2270 // behind the number of full collections started. 2271 2272 // This is the case for the inner caller, i.e. a Full GC. 2273 assert(concurrent || 2274 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2275 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2276 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2277 "is inconsistent with _old_marking_cycles_completed = %u", 2278 _old_marking_cycles_started, _old_marking_cycles_completed)); 2279 2280 // This is the case for the outer caller, i.e. the concurrent cycle. 2281 assert(!concurrent || 2282 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2283 err_msg("for outer caller (concurrent cycle): " 2284 "_old_marking_cycles_started = %u " 2285 "is inconsistent with _old_marking_cycles_completed = %u", 2286 _old_marking_cycles_started, _old_marking_cycles_completed)); 2287 2288 _old_marking_cycles_completed += 1; 2289 2290 // We need to clear the "in_progress" flag in the CM thread before 2291 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2292 // is set) so that if a waiter requests another System.gc() it doesn't 2293 // incorrectly see that a marking cycle is still in progress. 2294 if (concurrent) { 2295 _cmThread->clear_in_progress(); 2296 } 2297 2298 // This notify_all() will ensure that a thread that called 2299 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2300 // and it's waiting for a full GC to finish will be woken up. It is 2301 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2302 FullGCCount_lock->notify_all(); 2303 } 2304 2305 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2306 _concurrent_cycle_started = true; 2307 _gc_timer_cm->register_gc_start(start_time); 2308 2309 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2310 trace_heap_before_gc(_gc_tracer_cm); 2311 } 2312 2313 void G1CollectedHeap::register_concurrent_cycle_end() { 2314 if (_concurrent_cycle_started) { 2315 if (_cm->has_aborted()) { 2316 _gc_tracer_cm->report_concurrent_mode_failure(); 2317 } 2318 2319 _gc_timer_cm->register_gc_end(); 2320 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2321 2322 // Clear state variables to prepare for the next concurrent cycle. 2323 _concurrent_cycle_started = false; 2324 _heap_summary_sent = false; 2325 } 2326 } 2327 2328 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2329 if (_concurrent_cycle_started) { 2330 // This function can be called when: 2331 // the cleanup pause is run 2332 // the concurrent cycle is aborted before the cleanup pause. 2333 // the concurrent cycle is aborted after the cleanup pause, 2334 // but before the concurrent cycle end has been registered. 2335 // Make sure that we only send the heap information once. 2336 if (!_heap_summary_sent) { 2337 trace_heap_after_gc(_gc_tracer_cm); 2338 _heap_summary_sent = true; 2339 } 2340 } 2341 } 2342 2343 G1YCType G1CollectedHeap::yc_type() { 2344 bool is_young = g1_policy()->gcs_are_young(); 2345 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2346 bool is_during_mark = mark_in_progress(); 2347 2348 if (is_initial_mark) { 2349 return InitialMark; 2350 } else if (is_during_mark) { 2351 return DuringMark; 2352 } else if (is_young) { 2353 return Normal; 2354 } else { 2355 return Mixed; 2356 } 2357 } 2358 2359 void G1CollectedHeap::collect(GCCause::Cause cause) { 2360 assert_heap_not_locked(); 2361 2362 uint gc_count_before; 2363 uint old_marking_count_before; 2364 uint full_gc_count_before; 2365 bool retry_gc; 2366 2367 do { 2368 retry_gc = false; 2369 2370 { 2371 MutexLocker ml(Heap_lock); 2372 2373 // Read the GC count while holding the Heap_lock 2374 gc_count_before = total_collections(); 2375 full_gc_count_before = total_full_collections(); 2376 old_marking_count_before = _old_marking_cycles_started; 2377 } 2378 2379 if (should_do_concurrent_full_gc(cause)) { 2380 // Schedule an initial-mark evacuation pause that will start a 2381 // concurrent cycle. We're setting word_size to 0 which means that 2382 // we are not requesting a post-GC allocation. 2383 VM_G1IncCollectionPause op(gc_count_before, 2384 0, /* word_size */ 2385 true, /* should_initiate_conc_mark */ 2386 g1_policy()->max_pause_time_ms(), 2387 cause); 2388 op.set_allocation_context(AllocationContext::current()); 2389 2390 VMThread::execute(&op); 2391 if (!op.pause_succeeded()) { 2392 if (old_marking_count_before == _old_marking_cycles_started) { 2393 retry_gc = op.should_retry_gc(); 2394 } else { 2395 // A Full GC happened while we were trying to schedule the 2396 // initial-mark GC. No point in starting a new cycle given 2397 // that the whole heap was collected anyway. 2398 } 2399 2400 if (retry_gc) { 2401 if (GC_locker::is_active_and_needs_gc()) { 2402 GC_locker::stall_until_clear(); 2403 } 2404 } 2405 } 2406 } else { 2407 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2408 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2409 2410 // Schedule a standard evacuation pause. We're setting word_size 2411 // to 0 which means that we are not requesting a post-GC allocation. 2412 VM_G1IncCollectionPause op(gc_count_before, 2413 0, /* word_size */ 2414 false, /* should_initiate_conc_mark */ 2415 g1_policy()->max_pause_time_ms(), 2416 cause); 2417 VMThread::execute(&op); 2418 } else { 2419 // Schedule a Full GC. 2420 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2421 VMThread::execute(&op); 2422 } 2423 } 2424 } while (retry_gc); 2425 } 2426 2427 bool G1CollectedHeap::is_in(const void* p) const { 2428 if (_hrm.reserved().contains(p)) { 2429 // Given that we know that p is in the reserved space, 2430 // heap_region_containing_raw() should successfully 2431 // return the containing region. 2432 HeapRegion* hr = heap_region_containing_raw(p); 2433 return hr->is_in(p); 2434 } else { 2435 return false; 2436 } 2437 } 2438 2439 #ifdef ASSERT 2440 bool G1CollectedHeap::is_in_exact(const void* p) const { 2441 bool contains = reserved_region().contains(p); 2442 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2443 if (contains && available) { 2444 return true; 2445 } else { 2446 return false; 2447 } 2448 } 2449 #endif 2450 2451 // Iteration functions. 2452 2453 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2454 2455 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2456 ExtendedOopClosure* _cl; 2457 public: 2458 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2459 bool doHeapRegion(HeapRegion* r) { 2460 if (!r->is_continues_humongous()) { 2461 r->oop_iterate(_cl); 2462 } 2463 return false; 2464 } 2465 }; 2466 2467 // Iterates an ObjectClosure over all objects within a HeapRegion. 2468 2469 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2470 ObjectClosure* _cl; 2471 public: 2472 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2473 bool doHeapRegion(HeapRegion* r) { 2474 if (!r->is_continues_humongous()) { 2475 r->object_iterate(_cl); 2476 } 2477 return false; 2478 } 2479 }; 2480 2481 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2482 IterateObjectClosureRegionClosure blk(cl); 2483 heap_region_iterate(&blk); 2484 } 2485 2486 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2487 _hrm.iterate(cl); 2488 } 2489 2490 void 2491 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, 2492 uint worker_id, 2493 HeapRegionClaimer *hrclaimer, 2494 bool concurrent) const { 2495 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); 2496 } 2497 2498 // Clear the cached CSet starting regions and (more importantly) 2499 // the time stamps. Called when we reset the GC time stamp. 2500 void G1CollectedHeap::clear_cset_start_regions() { 2501 assert(_worker_cset_start_region != NULL, "sanity"); 2502 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2503 2504 int n_queues = MAX2((int)ParallelGCThreads, 1); 2505 for (int i = 0; i < n_queues; i++) { 2506 _worker_cset_start_region[i] = NULL; 2507 _worker_cset_start_region_time_stamp[i] = 0; 2508 } 2509 } 2510 2511 // Given the id of a worker, obtain or calculate a suitable 2512 // starting region for iterating over the current collection set. 2513 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2514 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2515 2516 HeapRegion* result = NULL; 2517 unsigned gc_time_stamp = get_gc_time_stamp(); 2518 2519 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2520 // Cached starting region for current worker was set 2521 // during the current pause - so it's valid. 2522 // Note: the cached starting heap region may be NULL 2523 // (when the collection set is empty). 2524 result = _worker_cset_start_region[worker_i]; 2525 assert(result == NULL || result->in_collection_set(), "sanity"); 2526 return result; 2527 } 2528 2529 // The cached entry was not valid so let's calculate 2530 // a suitable starting heap region for this worker. 2531 2532 // We want the parallel threads to start their collection 2533 // set iteration at different collection set regions to 2534 // avoid contention. 2535 // If we have: 2536 // n collection set regions 2537 // p threads 2538 // Then thread t will start at region floor ((t * n) / p) 2539 2540 result = g1_policy()->collection_set(); 2541 uint cs_size = g1_policy()->cset_region_length(); 2542 uint active_workers = workers()->active_workers(); 2543 assert(UseDynamicNumberOfGCThreads || 2544 active_workers == workers()->total_workers(), 2545 "Unless dynamic should use total workers"); 2546 2547 uint end_ind = (cs_size * worker_i) / active_workers; 2548 uint start_ind = 0; 2549 2550 if (worker_i > 0 && 2551 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2552 // Previous workers starting region is valid 2553 // so let's iterate from there 2554 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2555 result = _worker_cset_start_region[worker_i - 1]; 2556 } 2557 2558 for (uint i = start_ind; i < end_ind; i++) { 2559 result = result->next_in_collection_set(); 2560 } 2561 2562 // Note: the calculated starting heap region may be NULL 2563 // (when the collection set is empty). 2564 assert(result == NULL || result->in_collection_set(), "sanity"); 2565 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2566 "should be updated only once per pause"); 2567 _worker_cset_start_region[worker_i] = result; 2568 OrderAccess::storestore(); 2569 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2570 return result; 2571 } 2572 2573 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2574 HeapRegion* r = g1_policy()->collection_set(); 2575 while (r != NULL) { 2576 HeapRegion* next = r->next_in_collection_set(); 2577 if (cl->doHeapRegion(r)) { 2578 cl->incomplete(); 2579 return; 2580 } 2581 r = next; 2582 } 2583 } 2584 2585 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2586 HeapRegionClosure *cl) { 2587 if (r == NULL) { 2588 // The CSet is empty so there's nothing to do. 2589 return; 2590 } 2591 2592 assert(r->in_collection_set(), 2593 "Start region must be a member of the collection set."); 2594 HeapRegion* cur = r; 2595 while (cur != NULL) { 2596 HeapRegion* next = cur->next_in_collection_set(); 2597 if (cl->doHeapRegion(cur) && false) { 2598 cl->incomplete(); 2599 return; 2600 } 2601 cur = next; 2602 } 2603 cur = g1_policy()->collection_set(); 2604 while (cur != r) { 2605 HeapRegion* next = cur->next_in_collection_set(); 2606 if (cl->doHeapRegion(cur) && false) { 2607 cl->incomplete(); 2608 return; 2609 } 2610 cur = next; 2611 } 2612 } 2613 2614 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2615 HeapRegion* result = _hrm.next_region_in_heap(from); 2616 while (result != NULL && result->is_humongous()) { 2617 result = _hrm.next_region_in_heap(result); 2618 } 2619 return result; 2620 } 2621 2622 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2623 HeapRegion* hr = heap_region_containing(addr); 2624 return hr->block_start(addr); 2625 } 2626 2627 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2628 HeapRegion* hr = heap_region_containing(addr); 2629 return hr->block_size(addr); 2630 } 2631 2632 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2633 HeapRegion* hr = heap_region_containing(addr); 2634 return hr->block_is_obj(addr); 2635 } 2636 2637 bool G1CollectedHeap::supports_tlab_allocation() const { 2638 return true; 2639 } 2640 2641 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2642 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2643 } 2644 2645 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2646 return young_list()->eden_used_bytes(); 2647 } 2648 2649 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2650 // must be smaller than the humongous object limit. 2651 size_t G1CollectedHeap::max_tlab_size() const { 2652 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 2653 } 2654 2655 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2656 // Return the remaining space in the cur alloc region, but not less than 2657 // the min TLAB size. 2658 2659 // Also, this value can be at most the humongous object threshold, 2660 // since we can't allow tlabs to grow big enough to accommodate 2661 // humongous objects. 2662 2663 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get(); 2664 size_t max_tlab = max_tlab_size() * wordSize; 2665 if (hr == NULL) { 2666 return max_tlab; 2667 } else { 2668 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 2669 } 2670 } 2671 2672 size_t G1CollectedHeap::max_capacity() const { 2673 return _hrm.reserved().byte_size(); 2674 } 2675 2676 jlong G1CollectedHeap::millis_since_last_gc() { 2677 // assert(false, "NYI"); 2678 return 0; 2679 } 2680 2681 void G1CollectedHeap::prepare_for_verify() { 2682 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2683 ensure_parsability(false); 2684 } 2685 g1_rem_set()->prepare_for_verify(); 2686 } 2687 2688 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 2689 VerifyOption vo) { 2690 switch (vo) { 2691 case VerifyOption_G1UsePrevMarking: 2692 return hr->obj_allocated_since_prev_marking(obj); 2693 case VerifyOption_G1UseNextMarking: 2694 return hr->obj_allocated_since_next_marking(obj); 2695 case VerifyOption_G1UseMarkWord: 2696 return false; 2697 default: 2698 ShouldNotReachHere(); 2699 } 2700 return false; // keep some compilers happy 2701 } 2702 2703 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 2704 switch (vo) { 2705 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 2706 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 2707 case VerifyOption_G1UseMarkWord: return NULL; 2708 default: ShouldNotReachHere(); 2709 } 2710 return NULL; // keep some compilers happy 2711 } 2712 2713 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 2714 switch (vo) { 2715 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 2716 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 2717 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 2718 default: ShouldNotReachHere(); 2719 } 2720 return false; // keep some compilers happy 2721 } 2722 2723 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 2724 switch (vo) { 2725 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 2726 case VerifyOption_G1UseNextMarking: return "NTAMS"; 2727 case VerifyOption_G1UseMarkWord: return "NONE"; 2728 default: ShouldNotReachHere(); 2729 } 2730 return NULL; // keep some compilers happy 2731 } 2732 2733 class VerifyRootsClosure: public OopClosure { 2734 private: 2735 G1CollectedHeap* _g1h; 2736 VerifyOption _vo; 2737 bool _failures; 2738 public: 2739 // _vo == UsePrevMarking -> use "prev" marking information, 2740 // _vo == UseNextMarking -> use "next" marking information, 2741 // _vo == UseMarkWord -> use mark word from object header. 2742 VerifyRootsClosure(VerifyOption vo) : 2743 _g1h(G1CollectedHeap::heap()), 2744 _vo(vo), 2745 _failures(false) { } 2746 2747 bool failures() { return _failures; } 2748 2749 template <class T> void do_oop_nv(T* p) { 2750 T heap_oop = oopDesc::load_heap_oop(p); 2751 if (!oopDesc::is_null(heap_oop)) { 2752 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2753 if (_g1h->is_obj_dead_cond(obj, _vo)) { 2754 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 2755 "points to dead obj "PTR_FORMAT, p, (void*) obj); 2756 if (_vo == VerifyOption_G1UseMarkWord) { 2757 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 2758 } 2759 obj->print_on(gclog_or_tty); 2760 _failures = true; 2761 } 2762 } 2763 } 2764 2765 void do_oop(oop* p) { do_oop_nv(p); } 2766 void do_oop(narrowOop* p) { do_oop_nv(p); } 2767 }; 2768 2769 class G1VerifyCodeRootOopClosure: public OopClosure { 2770 G1CollectedHeap* _g1h; 2771 OopClosure* _root_cl; 2772 nmethod* _nm; 2773 VerifyOption _vo; 2774 bool _failures; 2775 2776 template <class T> void do_oop_work(T* p) { 2777 // First verify that this root is live 2778 _root_cl->do_oop(p); 2779 2780 if (!G1VerifyHeapRegionCodeRoots) { 2781 // We're not verifying the code roots attached to heap region. 2782 return; 2783 } 2784 2785 // Don't check the code roots during marking verification in a full GC 2786 if (_vo == VerifyOption_G1UseMarkWord) { 2787 return; 2788 } 2789 2790 // Now verify that the current nmethod (which contains p) is 2791 // in the code root list of the heap region containing the 2792 // object referenced by p. 2793 2794 T heap_oop = oopDesc::load_heap_oop(p); 2795 if (!oopDesc::is_null(heap_oop)) { 2796 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2797 2798 // Now fetch the region containing the object 2799 HeapRegion* hr = _g1h->heap_region_containing(obj); 2800 HeapRegionRemSet* hrrs = hr->rem_set(); 2801 // Verify that the strong code root list for this region 2802 // contains the nmethod 2803 if (!hrrs->strong_code_roots_list_contains(_nm)) { 2804 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " 2805 "from nmethod "PTR_FORMAT" not in strong " 2806 "code roots for region ["PTR_FORMAT","PTR_FORMAT")", 2807 p, _nm, hr->bottom(), hr->end()); 2808 _failures = true; 2809 } 2810 } 2811 } 2812 2813 public: 2814 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 2815 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 2816 2817 void do_oop(oop* p) { do_oop_work(p); } 2818 void do_oop(narrowOop* p) { do_oop_work(p); } 2819 2820 void set_nmethod(nmethod* nm) { _nm = nm; } 2821 bool failures() { return _failures; } 2822 }; 2823 2824 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 2825 G1VerifyCodeRootOopClosure* _oop_cl; 2826 2827 public: 2828 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 2829 _oop_cl(oop_cl) {} 2830 2831 void do_code_blob(CodeBlob* cb) { 2832 nmethod* nm = cb->as_nmethod_or_null(); 2833 if (nm != NULL) { 2834 _oop_cl->set_nmethod(nm); 2835 nm->oops_do(_oop_cl); 2836 } 2837 } 2838 }; 2839 2840 class YoungRefCounterClosure : public OopClosure { 2841 G1CollectedHeap* _g1h; 2842 int _count; 2843 public: 2844 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 2845 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 2846 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 2847 2848 int count() { return _count; } 2849 void reset_count() { _count = 0; }; 2850 }; 2851 2852 class VerifyKlassClosure: public KlassClosure { 2853 YoungRefCounterClosure _young_ref_counter_closure; 2854 OopClosure *_oop_closure; 2855 public: 2856 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 2857 void do_klass(Klass* k) { 2858 k->oops_do(_oop_closure); 2859 2860 _young_ref_counter_closure.reset_count(); 2861 k->oops_do(&_young_ref_counter_closure); 2862 if (_young_ref_counter_closure.count() > 0) { 2863 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k)); 2864 } 2865 } 2866 }; 2867 2868 class VerifyLivenessOopClosure: public OopClosure { 2869 G1CollectedHeap* _g1h; 2870 VerifyOption _vo; 2871 public: 2872 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 2873 _g1h(g1h), _vo(vo) 2874 { } 2875 void do_oop(narrowOop *p) { do_oop_work(p); } 2876 void do_oop( oop *p) { do_oop_work(p); } 2877 2878 template <class T> void do_oop_work(T *p) { 2879 oop obj = oopDesc::load_decode_heap_oop(p); 2880 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 2881 "Dead object referenced by a not dead object"); 2882 } 2883 }; 2884 2885 class VerifyObjsInRegionClosure: public ObjectClosure { 2886 private: 2887 G1CollectedHeap* _g1h; 2888 size_t _live_bytes; 2889 HeapRegion *_hr; 2890 VerifyOption _vo; 2891 public: 2892 // _vo == UsePrevMarking -> use "prev" marking information, 2893 // _vo == UseNextMarking -> use "next" marking information, 2894 // _vo == UseMarkWord -> use mark word from object header. 2895 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 2896 : _live_bytes(0), _hr(hr), _vo(vo) { 2897 _g1h = G1CollectedHeap::heap(); 2898 } 2899 void do_object(oop o) { 2900 VerifyLivenessOopClosure isLive(_g1h, _vo); 2901 assert(o != NULL, "Huh?"); 2902 if (!_g1h->is_obj_dead_cond(o, _vo)) { 2903 // If the object is alive according to the mark word, 2904 // then verify that the marking information agrees. 2905 // Note we can't verify the contra-positive of the 2906 // above: if the object is dead (according to the mark 2907 // word), it may not be marked, or may have been marked 2908 // but has since became dead, or may have been allocated 2909 // since the last marking. 2910 if (_vo == VerifyOption_G1UseMarkWord) { 2911 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 2912 } 2913 2914 o->oop_iterate_no_header(&isLive); 2915 if (!_hr->obj_allocated_since_prev_marking(o)) { 2916 size_t obj_size = o->size(); // Make sure we don't overflow 2917 _live_bytes += (obj_size * HeapWordSize); 2918 } 2919 } 2920 } 2921 size_t live_bytes() { return _live_bytes; } 2922 }; 2923 2924 class PrintObjsInRegionClosure : public ObjectClosure { 2925 HeapRegion *_hr; 2926 G1CollectedHeap *_g1; 2927 public: 2928 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 2929 _g1 = G1CollectedHeap::heap(); 2930 }; 2931 2932 void do_object(oop o) { 2933 if (o != NULL) { 2934 HeapWord *start = (HeapWord *) o; 2935 size_t word_sz = o->size(); 2936 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 2937 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 2938 (void*) o, word_sz, 2939 _g1->isMarkedPrev(o), 2940 _g1->isMarkedNext(o), 2941 _hr->obj_allocated_since_prev_marking(o)); 2942 HeapWord *end = start + word_sz; 2943 HeapWord *cur; 2944 int *val; 2945 for (cur = start; cur < end; cur++) { 2946 val = (int *) cur; 2947 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val); 2948 } 2949 } 2950 } 2951 }; 2952 2953 class VerifyRegionClosure: public HeapRegionClosure { 2954 private: 2955 bool _par; 2956 VerifyOption _vo; 2957 bool _failures; 2958 public: 2959 // _vo == UsePrevMarking -> use "prev" marking information, 2960 // _vo == UseNextMarking -> use "next" marking information, 2961 // _vo == UseMarkWord -> use mark word from object header. 2962 VerifyRegionClosure(bool par, VerifyOption vo) 2963 : _par(par), 2964 _vo(vo), 2965 _failures(false) {} 2966 2967 bool failures() { 2968 return _failures; 2969 } 2970 2971 bool doHeapRegion(HeapRegion* r) { 2972 if (!r->is_continues_humongous()) { 2973 bool failures = false; 2974 r->verify(_vo, &failures); 2975 if (failures) { 2976 _failures = true; 2977 } else { 2978 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 2979 r->object_iterate(¬_dead_yet_cl); 2980 if (_vo != VerifyOption_G1UseNextMarking) { 2981 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 2982 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 2983 "max_live_bytes "SIZE_FORMAT" " 2984 "< calculated "SIZE_FORMAT, 2985 r->bottom(), r->end(), 2986 r->max_live_bytes(), 2987 not_dead_yet_cl.live_bytes()); 2988 _failures = true; 2989 } 2990 } else { 2991 // When vo == UseNextMarking we cannot currently do a sanity 2992 // check on the live bytes as the calculation has not been 2993 // finalized yet. 2994 } 2995 } 2996 } 2997 return false; // stop the region iteration if we hit a failure 2998 } 2999 }; 3000 3001 // This is the task used for parallel verification of the heap regions 3002 3003 class G1ParVerifyTask: public AbstractGangTask { 3004 private: 3005 G1CollectedHeap* _g1h; 3006 VerifyOption _vo; 3007 bool _failures; 3008 HeapRegionClaimer _hrclaimer; 3009 3010 public: 3011 // _vo == UsePrevMarking -> use "prev" marking information, 3012 // _vo == UseNextMarking -> use "next" marking information, 3013 // _vo == UseMarkWord -> use mark word from object header. 3014 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3015 AbstractGangTask("Parallel verify task"), 3016 _g1h(g1h), 3017 _vo(vo), 3018 _failures(false), 3019 _hrclaimer(g1h->workers()->active_workers()) {} 3020 3021 bool failures() { 3022 return _failures; 3023 } 3024 3025 void work(uint worker_id) { 3026 HandleMark hm; 3027 VerifyRegionClosure blk(true, _vo); 3028 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer); 3029 if (blk.failures()) { 3030 _failures = true; 3031 } 3032 } 3033 }; 3034 3035 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3036 if (SafepointSynchronize::is_at_safepoint()) { 3037 assert(Thread::current()->is_VM_thread(), 3038 "Expected to be executed serially by the VM thread at this point"); 3039 3040 if (!silent) { gclog_or_tty->print("Roots "); } 3041 VerifyRootsClosure rootsCl(vo); 3042 VerifyKlassClosure klassCl(this, &rootsCl); 3043 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3044 3045 // We apply the relevant closures to all the oops in the 3046 // system dictionary, class loader data graph, the string table 3047 // and the nmethods in the code cache. 3048 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3049 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3050 3051 { 3052 G1RootProcessor root_processor(this); 3053 root_processor.process_all_roots(&rootsCl, 3054 &cldCl, 3055 &blobsCl); 3056 } 3057 3058 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3059 3060 if (vo != VerifyOption_G1UseMarkWord) { 3061 // If we're verifying during a full GC then the region sets 3062 // will have been torn down at the start of the GC. Therefore 3063 // verifying the region sets will fail. So we only verify 3064 // the region sets when not in a full GC. 3065 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3066 verify_region_sets(); 3067 } 3068 3069 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3070 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3071 3072 G1ParVerifyTask task(this, vo); 3073 assert(UseDynamicNumberOfGCThreads || 3074 workers()->active_workers() == workers()->total_workers(), 3075 "If not dynamic should be using all the workers"); 3076 uint n_workers = workers()->active_workers(); 3077 set_par_threads(n_workers); 3078 workers()->run_task(&task); 3079 set_par_threads(0); 3080 if (task.failures()) { 3081 failures = true; 3082 } 3083 3084 } else { 3085 VerifyRegionClosure blk(false, vo); 3086 heap_region_iterate(&blk); 3087 if (blk.failures()) { 3088 failures = true; 3089 } 3090 } 3091 3092 if (G1StringDedup::is_enabled()) { 3093 if (!silent) gclog_or_tty->print("StrDedup "); 3094 G1StringDedup::verify(); 3095 } 3096 3097 if (failures) { 3098 gclog_or_tty->print_cr("Heap:"); 3099 // It helps to have the per-region information in the output to 3100 // help us track down what went wrong. This is why we call 3101 // print_extended_on() instead of print_on(). 3102 print_extended_on(gclog_or_tty); 3103 gclog_or_tty->cr(); 3104 gclog_or_tty->flush(); 3105 } 3106 guarantee(!failures, "there should not have been any failures"); 3107 } else { 3108 if (!silent) { 3109 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3110 if (G1StringDedup::is_enabled()) { 3111 gclog_or_tty->print(", StrDedup"); 3112 } 3113 gclog_or_tty->print(") "); 3114 } 3115 } 3116 } 3117 3118 void G1CollectedHeap::verify(bool silent) { 3119 verify(silent, VerifyOption_G1UsePrevMarking); 3120 } 3121 3122 double G1CollectedHeap::verify(bool guard, const char* msg) { 3123 double verify_time_ms = 0.0; 3124 3125 if (guard && total_collections() >= VerifyGCStartAt) { 3126 double verify_start = os::elapsedTime(); 3127 HandleMark hm; // Discard invalid handles created during verification 3128 prepare_for_verify(); 3129 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3130 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3131 } 3132 3133 return verify_time_ms; 3134 } 3135 3136 void G1CollectedHeap::verify_before_gc() { 3137 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3138 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3139 } 3140 3141 void G1CollectedHeap::verify_after_gc() { 3142 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3143 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3144 } 3145 3146 class PrintRegionClosure: public HeapRegionClosure { 3147 outputStream* _st; 3148 public: 3149 PrintRegionClosure(outputStream* st) : _st(st) {} 3150 bool doHeapRegion(HeapRegion* r) { 3151 r->print_on(_st); 3152 return false; 3153 } 3154 }; 3155 3156 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3157 const HeapRegion* hr, 3158 const VerifyOption vo) const { 3159 switch (vo) { 3160 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3161 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3162 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3163 default: ShouldNotReachHere(); 3164 } 3165 return false; // keep some compilers happy 3166 } 3167 3168 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3169 const VerifyOption vo) const { 3170 switch (vo) { 3171 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3172 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3173 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3174 default: ShouldNotReachHere(); 3175 } 3176 return false; // keep some compilers happy 3177 } 3178 3179 void G1CollectedHeap::print_on(outputStream* st) const { 3180 st->print(" %-20s", "garbage-first heap"); 3181 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3182 capacity()/K, used_unlocked()/K); 3183 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3184 _hrm.reserved().start(), 3185 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords, 3186 _hrm.reserved().end()); 3187 st->cr(); 3188 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3189 uint young_regions = _young_list->length(); 3190 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3191 (size_t) young_regions * HeapRegion::GrainBytes / K); 3192 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3193 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3194 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3195 st->cr(); 3196 MetaspaceAux::print_on(st); 3197 } 3198 3199 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3200 print_on(st); 3201 3202 // Print the per-region information. 3203 st->cr(); 3204 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3205 "HS=humongous(starts), HC=humongous(continues), " 3206 "CS=collection set, F=free, TS=gc time stamp, " 3207 "PTAMS=previous top-at-mark-start, " 3208 "NTAMS=next top-at-mark-start)"); 3209 PrintRegionClosure blk(st); 3210 heap_region_iterate(&blk); 3211 } 3212 3213 void G1CollectedHeap::print_on_error(outputStream* st) const { 3214 this->CollectedHeap::print_on_error(st); 3215 3216 if (_cm != NULL) { 3217 st->cr(); 3218 _cm->print_on_error(st); 3219 } 3220 } 3221 3222 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3223 workers()->print_worker_threads_on(st); 3224 _cmThread->print_on(st); 3225 st->cr(); 3226 _cm->print_worker_threads_on(st); 3227 _cg1r->print_worker_threads_on(st); 3228 if (G1StringDedup::is_enabled()) { 3229 G1StringDedup::print_worker_threads_on(st); 3230 } 3231 } 3232 3233 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3234 workers()->threads_do(tc); 3235 tc->do_thread(_cmThread); 3236 _cg1r->threads_do(tc); 3237 if (G1StringDedup::is_enabled()) { 3238 G1StringDedup::threads_do(tc); 3239 } 3240 } 3241 3242 void G1CollectedHeap::print_tracing_info() const { 3243 // We'll overload this to mean "trace GC pause statistics." 3244 if (TraceYoungGenTime || TraceOldGenTime) { 3245 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3246 // to that. 3247 g1_policy()->print_tracing_info(); 3248 } 3249 if (G1SummarizeRSetStats) { 3250 g1_rem_set()->print_summary_info(); 3251 } 3252 if (G1SummarizeConcMark) { 3253 concurrent_mark()->print_summary_info(); 3254 } 3255 g1_policy()->print_yg_surv_rate_info(); 3256 } 3257 3258 #ifndef PRODUCT 3259 // Helpful for debugging RSet issues. 3260 3261 class PrintRSetsClosure : public HeapRegionClosure { 3262 private: 3263 const char* _msg; 3264 size_t _occupied_sum; 3265 3266 public: 3267 bool doHeapRegion(HeapRegion* r) { 3268 HeapRegionRemSet* hrrs = r->rem_set(); 3269 size_t occupied = hrrs->occupied(); 3270 _occupied_sum += occupied; 3271 3272 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3273 HR_FORMAT_PARAMS(r)); 3274 if (occupied == 0) { 3275 gclog_or_tty->print_cr(" RSet is empty"); 3276 } else { 3277 hrrs->print(); 3278 } 3279 gclog_or_tty->print_cr("----------"); 3280 return false; 3281 } 3282 3283 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3284 gclog_or_tty->cr(); 3285 gclog_or_tty->print_cr("========================================"); 3286 gclog_or_tty->print_cr("%s", msg); 3287 gclog_or_tty->cr(); 3288 } 3289 3290 ~PrintRSetsClosure() { 3291 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3292 gclog_or_tty->print_cr("========================================"); 3293 gclog_or_tty->cr(); 3294 } 3295 }; 3296 3297 void G1CollectedHeap::print_cset_rsets() { 3298 PrintRSetsClosure cl("Printing CSet RSets"); 3299 collection_set_iterate(&cl); 3300 } 3301 3302 void G1CollectedHeap::print_all_rsets() { 3303 PrintRSetsClosure cl("Printing All RSets");; 3304 heap_region_iterate(&cl); 3305 } 3306 #endif // PRODUCT 3307 3308 G1CollectedHeap* G1CollectedHeap::heap() { 3309 CollectedHeap* heap = Universe::heap(); 3310 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 3311 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); 3312 return (G1CollectedHeap*)heap; 3313 } 3314 3315 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3316 // always_do_update_barrier = false; 3317 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3318 // Fill TLAB's and such 3319 accumulate_statistics_all_tlabs(); 3320 ensure_parsability(true); 3321 3322 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3323 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3324 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3325 } 3326 } 3327 3328 void G1CollectedHeap::gc_epilogue(bool full) { 3329 3330 if (G1SummarizeRSetStats && 3331 (G1SummarizeRSetStatsPeriod > 0) && 3332 // we are at the end of the GC. Total collections has already been increased. 3333 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3334 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3335 } 3336 3337 // FIXME: what is this about? 3338 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3339 // is set. 3340 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3341 "derived pointer present")); 3342 // always_do_update_barrier = true; 3343 3344 resize_all_tlabs(); 3345 allocation_context_stats().update(full); 3346 3347 // We have just completed a GC. Update the soft reference 3348 // policy with the new heap occupancy 3349 Universe::update_heap_info_at_gc(); 3350 } 3351 3352 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3353 uint gc_count_before, 3354 bool* succeeded, 3355 GCCause::Cause gc_cause) { 3356 assert_heap_not_locked_and_not_at_safepoint(); 3357 g1_policy()->record_stop_world_start(); 3358 VM_G1IncCollectionPause op(gc_count_before, 3359 word_size, 3360 false, /* should_initiate_conc_mark */ 3361 g1_policy()->max_pause_time_ms(), 3362 gc_cause); 3363 3364 op.set_allocation_context(AllocationContext::current()); 3365 VMThread::execute(&op); 3366 3367 HeapWord* result = op.result(); 3368 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3369 assert(result == NULL || ret_succeeded, 3370 "the result should be NULL if the VM did not succeed"); 3371 *succeeded = ret_succeeded; 3372 3373 assert_heap_not_locked(); 3374 return result; 3375 } 3376 3377 void 3378 G1CollectedHeap::doConcurrentMark() { 3379 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3380 if (!_cmThread->in_progress()) { 3381 _cmThread->set_started(); 3382 CGC_lock->notify(); 3383 } 3384 } 3385 3386 size_t G1CollectedHeap::pending_card_num() { 3387 size_t extra_cards = 0; 3388 JavaThread *curr = Threads::first(); 3389 while (curr != NULL) { 3390 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3391 extra_cards += dcq.size(); 3392 curr = curr->next(); 3393 } 3394 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3395 size_t buffer_size = dcqs.buffer_size(); 3396 size_t buffer_num = dcqs.completed_buffers_num(); 3397 3398 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3399 // in bytes - not the number of 'entries'. We need to convert 3400 // into a number of cards. 3401 return (buffer_size * buffer_num + extra_cards) / oopSize; 3402 } 3403 3404 size_t G1CollectedHeap::cards_scanned() { 3405 return g1_rem_set()->cardsScanned(); 3406 } 3407 3408 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3409 private: 3410 size_t _total_humongous; 3411 size_t _candidate_humongous; 3412 3413 DirtyCardQueue _dcq; 3414 3415 // We don't nominate objects with many remembered set entries, on 3416 // the assumption that such objects are likely still live. 3417 bool is_remset_small(HeapRegion* region) const { 3418 HeapRegionRemSet* const rset = region->rem_set(); 3419 return G1EagerReclaimHumongousObjectsWithStaleRefs 3420 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) 3421 : rset->is_empty(); 3422 } 3423 3424 bool is_typeArray_region(HeapRegion* region) const { 3425 return oop(region->bottom())->is_typeArray(); 3426 } 3427 3428 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { 3429 assert(region->is_starts_humongous(), "Must start a humongous object"); 3430 3431 // Candidate selection must satisfy the following constraints 3432 // while concurrent marking is in progress: 3433 // 3434 // * In order to maintain SATB invariants, an object must not be 3435 // reclaimed if it was allocated before the start of marking and 3436 // has not had its references scanned. Such an object must have 3437 // its references (including type metadata) scanned to ensure no 3438 // live objects are missed by the marking process. Objects 3439 // allocated after the start of concurrent marking don't need to 3440 // be scanned. 3441 // 3442 // * An object must not be reclaimed if it is on the concurrent 3443 // mark stack. Objects allocated after the start of concurrent 3444 // marking are never pushed on the mark stack. 3445 // 3446 // Nominating only objects allocated after the start of concurrent 3447 // marking is sufficient to meet both constraints. This may miss 3448 // some objects that satisfy the constraints, but the marking data 3449 // structures don't support efficiently performing the needed 3450 // additional tests or scrubbing of the mark stack. 3451 // 3452 // However, we presently only nominate is_typeArray() objects. 3453 // A humongous object containing references induces remembered 3454 // set entries on other regions. In order to reclaim such an 3455 // object, those remembered sets would need to be cleaned up. 3456 // 3457 // We also treat is_typeArray() objects specially, allowing them 3458 // to be reclaimed even if allocated before the start of 3459 // concurrent mark. For this we rely on mark stack insertion to 3460 // exclude is_typeArray() objects, preventing reclaiming an object 3461 // that is in the mark stack. We also rely on the metadata for 3462 // such objects to be built-in and so ensured to be kept live. 3463 // Frequent allocation and drop of large binary blobs is an 3464 // important use case for eager reclaim, and this special handling 3465 // may reduce needed headroom. 3466 3467 return is_typeArray_region(region) && is_remset_small(region); 3468 } 3469 3470 public: 3471 RegisterHumongousWithInCSetFastTestClosure() 3472 : _total_humongous(0), 3473 _candidate_humongous(0), 3474 _dcq(&JavaThread::dirty_card_queue_set()) { 3475 } 3476 3477 virtual bool doHeapRegion(HeapRegion* r) { 3478 if (!r->is_starts_humongous()) { 3479 return false; 3480 } 3481 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3482 3483 bool is_candidate = humongous_region_is_candidate(g1h, r); 3484 uint rindex = r->hrm_index(); 3485 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 3486 if (is_candidate) { 3487 _candidate_humongous++; 3488 g1h->register_humongous_region_with_cset(rindex); 3489 // Is_candidate already filters out humongous object with large remembered sets. 3490 // If we have a humongous object with a few remembered sets, we simply flush these 3491 // remembered set entries into the DCQS. That will result in automatic 3492 // re-evaluation of their remembered set entries during the following evacuation 3493 // phase. 3494 if (!r->rem_set()->is_empty()) { 3495 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 3496 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 3497 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 3498 HeapRegionRemSetIterator hrrs(r->rem_set()); 3499 size_t card_index; 3500 while (hrrs.has_next(card_index)) { 3501 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 3502 // The remembered set might contain references to already freed 3503 // regions. Filter out such entries to avoid failing card table 3504 // verification. 3505 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) { 3506 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 3507 *card_ptr = CardTableModRefBS::dirty_card_val(); 3508 _dcq.enqueue(card_ptr); 3509 } 3510 } 3511 } 3512 r->rem_set()->clear_locked(); 3513 } 3514 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 3515 } 3516 _total_humongous++; 3517 3518 return false; 3519 } 3520 3521 size_t total_humongous() const { return _total_humongous; } 3522 size_t candidate_humongous() const { return _candidate_humongous; } 3523 3524 void flush_rem_set_entries() { _dcq.flush(); } 3525 }; 3526 3527 void G1CollectedHeap::register_humongous_regions_with_cset() { 3528 if (!G1EagerReclaimHumongousObjects) { 3529 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 3530 return; 3531 } 3532 double time = os::elapsed_counter(); 3533 3534 // Collect reclaim candidate information and register candidates with cset. 3535 RegisterHumongousWithInCSetFastTestClosure cl; 3536 heap_region_iterate(&cl); 3537 3538 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 3539 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 3540 cl.total_humongous(), 3541 cl.candidate_humongous()); 3542 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3543 3544 // Finally flush all remembered set entries to re-check into the global DCQS. 3545 cl.flush_rem_set_entries(); 3546 } 3547 3548 void 3549 G1CollectedHeap::setup_surviving_young_words() { 3550 assert(_surviving_young_words == NULL, "pre-condition"); 3551 uint array_length = g1_policy()->young_cset_region_length(); 3552 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3553 if (_surviving_young_words == NULL) { 3554 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3555 "Not enough space for young surv words summary."); 3556 } 3557 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3558 #ifdef ASSERT 3559 for (uint i = 0; i < array_length; ++i) { 3560 assert( _surviving_young_words[i] == 0, "memset above" ); 3561 } 3562 #endif // !ASSERT 3563 } 3564 3565 void 3566 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3567 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3568 uint array_length = g1_policy()->young_cset_region_length(); 3569 for (uint i = 0; i < array_length; ++i) { 3570 _surviving_young_words[i] += surv_young_words[i]; 3571 } 3572 } 3573 3574 void 3575 G1CollectedHeap::cleanup_surviving_young_words() { 3576 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3577 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words); 3578 _surviving_young_words = NULL; 3579 } 3580 3581 #ifdef ASSERT 3582 class VerifyCSetClosure: public HeapRegionClosure { 3583 public: 3584 bool doHeapRegion(HeapRegion* hr) { 3585 // Here we check that the CSet region's RSet is ready for parallel 3586 // iteration. The fields that we'll verify are only manipulated 3587 // when the region is part of a CSet and is collected. Afterwards, 3588 // we reset these fields when we clear the region's RSet (when the 3589 // region is freed) so they are ready when the region is 3590 // re-allocated. The only exception to this is if there's an 3591 // evacuation failure and instead of freeing the region we leave 3592 // it in the heap. In that case, we reset these fields during 3593 // evacuation failure handling. 3594 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3595 3596 // Here's a good place to add any other checks we'd like to 3597 // perform on CSet regions. 3598 return false; 3599 } 3600 }; 3601 #endif // ASSERT 3602 3603 #if TASKQUEUE_STATS 3604 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3605 st->print_raw_cr("GC Task Stats"); 3606 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3607 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3608 } 3609 3610 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3611 print_taskqueue_stats_hdr(st); 3612 3613 TaskQueueStats totals; 3614 const uint n = workers()->total_workers(); 3615 for (uint i = 0; i < n; ++i) { 3616 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3617 totals += task_queue(i)->stats; 3618 } 3619 st->print_raw("tot "); totals.print(st); st->cr(); 3620 3621 DEBUG_ONLY(totals.verify()); 3622 } 3623 3624 void G1CollectedHeap::reset_taskqueue_stats() { 3625 const uint n = workers()->total_workers(); 3626 for (uint i = 0; i < n; ++i) { 3627 task_queue(i)->stats.reset(); 3628 } 3629 } 3630 #endif // TASKQUEUE_STATS 3631 3632 void G1CollectedHeap::log_gc_header() { 3633 if (!G1Log::fine()) { 3634 return; 3635 } 3636 3637 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id()); 3638 3639 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3640 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") 3641 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3642 3643 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3644 } 3645 3646 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3647 if (!G1Log::fine()) { 3648 return; 3649 } 3650 3651 if (G1Log::finer()) { 3652 if (evacuation_failed()) { 3653 gclog_or_tty->print(" (to-space exhausted)"); 3654 } 3655 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3656 g1_policy()->phase_times()->note_gc_end(); 3657 g1_policy()->phase_times()->print(pause_time_sec); 3658 g1_policy()->print_detailed_heap_transition(); 3659 } else { 3660 if (evacuation_failed()) { 3661 gclog_or_tty->print("--"); 3662 } 3663 g1_policy()->print_heap_transition(); 3664 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3665 } 3666 gclog_or_tty->flush(); 3667 } 3668 3669 bool 3670 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3671 assert_at_safepoint(true /* should_be_vm_thread */); 3672 guarantee(!is_gc_active(), "collection is not reentrant"); 3673 3674 if (GC_locker::check_active_before_gc()) { 3675 return false; 3676 } 3677 3678 _gc_timer_stw->register_gc_start(); 3679 3680 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3681 3682 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3683 ResourceMark rm; 3684 3685 print_heap_before_gc(); 3686 trace_heap_before_gc(_gc_tracer_stw); 3687 3688 verify_region_sets_optional(); 3689 verify_dirty_young_regions(); 3690 3691 // This call will decide whether this pause is an initial-mark 3692 // pause. If it is, during_initial_mark_pause() will return true 3693 // for the duration of this pause. 3694 g1_policy()->decide_on_conc_mark_initiation(); 3695 3696 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3697 assert(!g1_policy()->during_initial_mark_pause() || 3698 g1_policy()->gcs_are_young(), "sanity"); 3699 3700 // We also do not allow mixed GCs during marking. 3701 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3702 3703 // Record whether this pause is an initial mark. When the current 3704 // thread has completed its logging output and it's safe to signal 3705 // the CM thread, the flag's value in the policy has been reset. 3706 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3707 3708 // Inner scope for scope based logging, timers, and stats collection 3709 { 3710 EvacuationInfo evacuation_info; 3711 3712 if (g1_policy()->during_initial_mark_pause()) { 3713 // We are about to start a marking cycle, so we increment the 3714 // full collection counter. 3715 increment_old_marking_cycles_started(); 3716 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3717 } 3718 3719 _gc_tracer_stw->report_yc_type(yc_type()); 3720 3721 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3722 3723 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 3724 workers()->active_workers(), 3725 Threads::number_of_non_daemon_threads()); 3726 assert(UseDynamicNumberOfGCThreads || 3727 active_workers == workers()->total_workers(), 3728 "If not dynamic should be using all the workers"); 3729 workers()->set_active_workers(active_workers); 3730 3731 double pause_start_sec = os::elapsedTime(); 3732 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress()); 3733 log_gc_header(); 3734 3735 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3736 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3737 3738 // If the secondary_free_list is not empty, append it to the 3739 // free_list. No need to wait for the cleanup operation to finish; 3740 // the region allocation code will check the secondary_free_list 3741 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3742 // set, skip this step so that the region allocation code has to 3743 // get entries from the secondary_free_list. 3744 if (!G1StressConcRegionFreeing) { 3745 append_secondary_free_list_if_not_empty_with_lock(); 3746 } 3747 3748 assert(check_young_list_well_formed(), "young list should be well formed"); 3749 3750 // Don't dynamically change the number of GC threads this early. A value of 3751 // 0 is used to indicate serial work. When parallel work is done, 3752 // it will be set. 3753 3754 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3755 IsGCActiveMark x; 3756 3757 gc_prologue(false); 3758 increment_total_collections(false /* full gc */); 3759 increment_gc_time_stamp(); 3760 3761 verify_before_gc(); 3762 3763 check_bitmaps("GC Start"); 3764 3765 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3766 3767 // Please see comment in g1CollectedHeap.hpp and 3768 // G1CollectedHeap::ref_processing_init() to see how 3769 // reference processing currently works in G1. 3770 3771 // Enable discovery in the STW reference processor 3772 ref_processor_stw()->enable_discovery(); 3773 3774 { 3775 // We want to temporarily turn off discovery by the 3776 // CM ref processor, if necessary, and turn it back on 3777 // on again later if we do. Using a scoped 3778 // NoRefDiscovery object will do this. 3779 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3780 3781 // Forget the current alloc region (we might even choose it to be part 3782 // of the collection set!). 3783 _allocator->release_mutator_alloc_region(); 3784 3785 // We should call this after we retire the mutator alloc 3786 // region(s) so that all the ALLOC / RETIRE events are generated 3787 // before the start GC event. 3788 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3789 3790 // This timing is only used by the ergonomics to handle our pause target. 3791 // It is unclear why this should not include the full pause. We will 3792 // investigate this in CR 7178365. 3793 // 3794 // Preserving the old comment here if that helps the investigation: 3795 // 3796 // The elapsed time induced by the start time below deliberately elides 3797 // the possible verification above. 3798 double sample_start_time_sec = os::elapsedTime(); 3799 3800 #if YOUNG_LIST_VERBOSE 3801 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 3802 _young_list->print(); 3803 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3804 #endif // YOUNG_LIST_VERBOSE 3805 3806 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3807 3808 double scan_wait_start = os::elapsedTime(); 3809 // We have to wait until the CM threads finish scanning the 3810 // root regions as it's the only way to ensure that all the 3811 // objects on them have been correctly scanned before we start 3812 // moving them during the GC. 3813 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3814 double wait_time_ms = 0.0; 3815 if (waited) { 3816 double scan_wait_end = os::elapsedTime(); 3817 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3818 } 3819 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3820 3821 #if YOUNG_LIST_VERBOSE 3822 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 3823 _young_list->print(); 3824 #endif // YOUNG_LIST_VERBOSE 3825 3826 if (g1_policy()->during_initial_mark_pause()) { 3827 concurrent_mark()->checkpointRootsInitialPre(); 3828 } 3829 3830 #if YOUNG_LIST_VERBOSE 3831 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 3832 _young_list->print(); 3833 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3834 #endif // YOUNG_LIST_VERBOSE 3835 3836 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 3837 3838 register_humongous_regions_with_cset(); 3839 3840 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3841 3842 _cm->note_start_of_gc(); 3843 // We should not verify the per-thread SATB buffers given that 3844 // we have not filtered them yet (we'll do so during the 3845 // GC). We also call this after finalize_cset() to 3846 // ensure that the CSet has been finalized. 3847 _cm->verify_no_cset_oops(true /* verify_stacks */, 3848 true /* verify_enqueued_buffers */, 3849 false /* verify_thread_buffers */, 3850 true /* verify_fingers */); 3851 3852 if (_hr_printer.is_active()) { 3853 HeapRegion* hr = g1_policy()->collection_set(); 3854 while (hr != NULL) { 3855 _hr_printer.cset(hr); 3856 hr = hr->next_in_collection_set(); 3857 } 3858 } 3859 3860 #ifdef ASSERT 3861 VerifyCSetClosure cl; 3862 collection_set_iterate(&cl); 3863 #endif // ASSERT 3864 3865 setup_surviving_young_words(); 3866 3867 // Initialize the GC alloc regions. 3868 _allocator->init_gc_alloc_regions(evacuation_info); 3869 3870 // Actually do the work... 3871 evacuate_collection_set(evacuation_info); 3872 3873 // We do this to mainly verify the per-thread SATB buffers 3874 // (which have been filtered by now) since we didn't verify 3875 // them earlier. No point in re-checking the stacks / enqueued 3876 // buffers given that the CSet has not changed since last time 3877 // we checked. 3878 _cm->verify_no_cset_oops(false /* verify_stacks */, 3879 false /* verify_enqueued_buffers */, 3880 true /* verify_thread_buffers */, 3881 true /* verify_fingers */); 3882 3883 free_collection_set(g1_policy()->collection_set(), evacuation_info); 3884 3885 eagerly_reclaim_humongous_regions(); 3886 3887 g1_policy()->clear_collection_set(); 3888 3889 cleanup_surviving_young_words(); 3890 3891 // Start a new incremental collection set for the next pause. 3892 g1_policy()->start_incremental_cset_building(); 3893 3894 clear_cset_fast_test(); 3895 3896 _young_list->reset_sampled_info(); 3897 3898 // Don't check the whole heap at this point as the 3899 // GC alloc regions from this pause have been tagged 3900 // as survivors and moved on to the survivor list. 3901 // Survivor regions will fail the !is_young() check. 3902 assert(check_young_list_empty(false /* check_heap */), 3903 "young list should be empty"); 3904 3905 #if YOUNG_LIST_VERBOSE 3906 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 3907 _young_list->print(); 3908 #endif // YOUNG_LIST_VERBOSE 3909 3910 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 3911 _young_list->first_survivor_region(), 3912 _young_list->last_survivor_region()); 3913 3914 _young_list->reset_auxilary_lists(); 3915 3916 if (evacuation_failed()) { 3917 _allocator->set_used(recalculate_used()); 3918 uint n_queues = MAX2((int)ParallelGCThreads, 1); 3919 for (uint i = 0; i < n_queues; i++) { 3920 if (_evacuation_failed_info_array[i].has_failed()) { 3921 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3922 } 3923 } 3924 } else { 3925 // The "used" of the the collection set have already been subtracted 3926 // when they were freed. Add in the bytes evacuated. 3927 _allocator->increase_used(g1_policy()->bytes_copied_during_gc()); 3928 } 3929 3930 if (g1_policy()->during_initial_mark_pause()) { 3931 // We have to do this before we notify the CM threads that 3932 // they can start working to make sure that all the 3933 // appropriate initialization is done on the CM object. 3934 concurrent_mark()->checkpointRootsInitialPost(); 3935 set_marking_started(); 3936 // Note that we don't actually trigger the CM thread at 3937 // this point. We do that later when we're sure that 3938 // the current thread has completed its logging output. 3939 } 3940 3941 allocate_dummy_regions(); 3942 3943 #if YOUNG_LIST_VERBOSE 3944 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 3945 _young_list->print(); 3946 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3947 #endif // YOUNG_LIST_VERBOSE 3948 3949 _allocator->init_mutator_alloc_region(); 3950 3951 { 3952 size_t expand_bytes = g1_policy()->expansion_amount(); 3953 if (expand_bytes > 0) { 3954 size_t bytes_before = capacity(); 3955 // No need for an ergo verbose message here, 3956 // expansion_amount() does this when it returns a value > 0. 3957 if (!expand(expand_bytes)) { 3958 // We failed to expand the heap. Cannot do anything about it. 3959 } 3960 } 3961 } 3962 3963 // We redo the verification but now wrt to the new CSet which 3964 // has just got initialized after the previous CSet was freed. 3965 _cm->verify_no_cset_oops(true /* verify_stacks */, 3966 true /* verify_enqueued_buffers */, 3967 true /* verify_thread_buffers */, 3968 true /* verify_fingers */); 3969 _cm->note_end_of_gc(); 3970 3971 // This timing is only used by the ergonomics to handle our pause target. 3972 // It is unclear why this should not include the full pause. We will 3973 // investigate this in CR 7178365. 3974 double sample_end_time_sec = os::elapsedTime(); 3975 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3976 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 3977 3978 MemoryService::track_memory_usage(); 3979 3980 // In prepare_for_verify() below we'll need to scan the deferred 3981 // update buffers to bring the RSets up-to-date if 3982 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 3983 // the update buffers we'll probably need to scan cards on the 3984 // regions we just allocated to (i.e., the GC alloc 3985 // regions). However, during the last GC we called 3986 // set_saved_mark() on all the GC alloc regions, so card 3987 // scanning might skip the [saved_mark_word()...top()] area of 3988 // those regions (i.e., the area we allocated objects into 3989 // during the last GC). But it shouldn't. Given that 3990 // saved_mark_word() is conditional on whether the GC time stamp 3991 // on the region is current or not, by incrementing the GC time 3992 // stamp here we invalidate all the GC time stamps on all the 3993 // regions and saved_mark_word() will simply return top() for 3994 // all the regions. This is a nicer way of ensuring this rather 3995 // than iterating over the regions and fixing them. In fact, the 3996 // GC time stamp increment here also ensures that 3997 // saved_mark_word() will return top() between pauses, i.e., 3998 // during concurrent refinement. So we don't need the 3999 // is_gc_active() check to decided which top to use when 4000 // scanning cards (see CR 7039627). 4001 increment_gc_time_stamp(); 4002 4003 verify_after_gc(); 4004 check_bitmaps("GC End"); 4005 4006 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4007 ref_processor_stw()->verify_no_references_recorded(); 4008 4009 // CM reference discovery will be re-enabled if necessary. 4010 } 4011 4012 // We should do this after we potentially expand the heap so 4013 // that all the COMMIT events are generated before the end GC 4014 // event, and after we retire the GC alloc regions so that all 4015 // RETIRE events are generated before the end GC event. 4016 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4017 4018 #ifdef TRACESPINNING 4019 ParallelTaskTerminator::print_termination_counts(); 4020 #endif 4021 4022 gc_epilogue(false); 4023 } 4024 4025 // Print the remainder of the GC log output. 4026 log_gc_footer(os::elapsedTime() - pause_start_sec); 4027 4028 // It is not yet to safe to tell the concurrent mark to 4029 // start as we have some optional output below. We don't want the 4030 // output from the concurrent mark thread interfering with this 4031 // logging output either. 4032 4033 _hrm.verify_optional(); 4034 verify_region_sets_optional(); 4035 4036 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats()); 4037 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4038 4039 print_heap_after_gc(); 4040 trace_heap_after_gc(_gc_tracer_stw); 4041 4042 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4043 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4044 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4045 // before any GC notifications are raised. 4046 g1mm()->update_sizes(); 4047 4048 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4049 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4050 _gc_timer_stw->register_gc_end(); 4051 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4052 } 4053 // It should now be safe to tell the concurrent mark thread to start 4054 // without its logging output interfering with the logging output 4055 // that came from the pause. 4056 4057 if (should_start_conc_mark) { 4058 // CAUTION: after the doConcurrentMark() call below, 4059 // the concurrent marking thread(s) could be running 4060 // concurrently with us. Make sure that anything after 4061 // this point does not assume that we are the only GC thread 4062 // running. Note: of course, the actual marking work will 4063 // not start until the safepoint itself is released in 4064 // SuspendibleThreadSet::desynchronize(). 4065 doConcurrentMark(); 4066 } 4067 4068 return true; 4069 } 4070 4071 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4072 _drain_in_progress = false; 4073 set_evac_failure_closure(cl); 4074 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4075 } 4076 4077 void G1CollectedHeap::finalize_for_evac_failure() { 4078 assert(_evac_failure_scan_stack != NULL && 4079 _evac_failure_scan_stack->length() == 0, 4080 "Postcondition"); 4081 assert(!_drain_in_progress, "Postcondition"); 4082 delete _evac_failure_scan_stack; 4083 _evac_failure_scan_stack = NULL; 4084 } 4085 4086 void G1CollectedHeap::remove_self_forwarding_pointers() { 4087 double remove_self_forwards_start = os::elapsedTime(); 4088 4089 set_par_threads(); 4090 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4091 workers()->run_task(&rsfp_task); 4092 set_par_threads(0); 4093 4094 // Now restore saved marks, if any. 4095 assert(_objs_with_preserved_marks.size() == 4096 _preserved_marks_of_objs.size(), "Both or none."); 4097 while (!_objs_with_preserved_marks.is_empty()) { 4098 oop obj = _objs_with_preserved_marks.pop(); 4099 markOop m = _preserved_marks_of_objs.pop(); 4100 obj->set_mark(m); 4101 } 4102 _objs_with_preserved_marks.clear(true); 4103 _preserved_marks_of_objs.clear(true); 4104 4105 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4106 } 4107 4108 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4109 _evac_failure_scan_stack->push(obj); 4110 } 4111 4112 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4113 assert(_evac_failure_scan_stack != NULL, "precondition"); 4114 4115 while (_evac_failure_scan_stack->length() > 0) { 4116 oop obj = _evac_failure_scan_stack->pop(); 4117 _evac_failure_closure->set_region(heap_region_containing(obj)); 4118 obj->oop_iterate_backwards(_evac_failure_closure); 4119 } 4120 } 4121 4122 oop 4123 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4124 oop old) { 4125 assert(obj_in_cs(old), 4126 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4127 (HeapWord*) old)); 4128 markOop m = old->mark(); 4129 oop forward_ptr = old->forward_to_atomic(old); 4130 if (forward_ptr == NULL) { 4131 // Forward-to-self succeeded. 4132 assert(_par_scan_state != NULL, "par scan state"); 4133 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4134 uint queue_num = _par_scan_state->queue_num(); 4135 4136 _evacuation_failed = true; 4137 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4138 if (_evac_failure_closure != cl) { 4139 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4140 assert(!_drain_in_progress, 4141 "Should only be true while someone holds the lock."); 4142 // Set the global evac-failure closure to the current thread's. 4143 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4144 set_evac_failure_closure(cl); 4145 // Now do the common part. 4146 handle_evacuation_failure_common(old, m); 4147 // Reset to NULL. 4148 set_evac_failure_closure(NULL); 4149 } else { 4150 // The lock is already held, and this is recursive. 4151 assert(_drain_in_progress, "This should only be the recursive case."); 4152 handle_evacuation_failure_common(old, m); 4153 } 4154 return old; 4155 } else { 4156 // Forward-to-self failed. Either someone else managed to allocate 4157 // space for this object (old != forward_ptr) or they beat us in 4158 // self-forwarding it (old == forward_ptr). 4159 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4160 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4161 "should not be in the CSet", 4162 (HeapWord*) old, (HeapWord*) forward_ptr)); 4163 return forward_ptr; 4164 } 4165 } 4166 4167 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4168 preserve_mark_if_necessary(old, m); 4169 4170 HeapRegion* r = heap_region_containing(old); 4171 if (!r->evacuation_failed()) { 4172 r->set_evacuation_failed(true); 4173 _hr_printer.evac_failure(r); 4174 } 4175 4176 push_on_evac_failure_scan_stack(old); 4177 4178 if (!_drain_in_progress) { 4179 // prevent recursion in copy_to_survivor_space() 4180 _drain_in_progress = true; 4181 drain_evac_failure_scan_stack(); 4182 _drain_in_progress = false; 4183 } 4184 } 4185 4186 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4187 assert(evacuation_failed(), "Oversaving!"); 4188 // We want to call the "for_promotion_failure" version only in the 4189 // case of a promotion failure. 4190 if (m->must_be_preserved_for_promotion_failure(obj)) { 4191 _objs_with_preserved_marks.push(obj); 4192 _preserved_marks_of_objs.push(m); 4193 } 4194 } 4195 4196 void G1ParCopyHelper::mark_object(oop obj) { 4197 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); 4198 4199 // We know that the object is not moving so it's safe to read its size. 4200 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4201 } 4202 4203 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4204 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4205 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4206 assert(from_obj != to_obj, "should not be self-forwarded"); 4207 4208 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); 4209 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); 4210 4211 // The object might be in the process of being copied by another 4212 // worker so we cannot trust that its to-space image is 4213 // well-formed. So we have to read its size from its from-space 4214 // image which we know should not be changing. 4215 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4216 } 4217 4218 template <class T> 4219 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4220 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4221 _scanned_klass->record_modified_oops(); 4222 } 4223 } 4224 4225 template <G1Barrier barrier, G1Mark do_mark_object> 4226 template <class T> 4227 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4228 T heap_oop = oopDesc::load_heap_oop(p); 4229 4230 if (oopDesc::is_null(heap_oop)) { 4231 return; 4232 } 4233 4234 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4235 4236 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4237 4238 const InCSetState state = _g1->in_cset_state(obj); 4239 if (state.is_in_cset()) { 4240 oop forwardee; 4241 markOop m = obj->mark(); 4242 if (m->is_marked()) { 4243 forwardee = (oop) m->decode_pointer(); 4244 } else { 4245 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m); 4246 } 4247 assert(forwardee != NULL, "forwardee should not be NULL"); 4248 oopDesc::encode_store_heap_oop(p, forwardee); 4249 if (do_mark_object != G1MarkNone && forwardee != obj) { 4250 // If the object is self-forwarded we don't need to explicitly 4251 // mark it, the evacuation failure protocol will do so. 4252 mark_forwarded_object(obj, forwardee); 4253 } 4254 4255 if (barrier == G1BarrierKlass) { 4256 do_klass_barrier(p, forwardee); 4257 } 4258 } else { 4259 if (state.is_humongous()) { 4260 _g1->set_humongous_is_live(obj); 4261 } 4262 // The object is not in collection set. If we're a root scanning 4263 // closure during an initial mark pause then attempt to mark the object. 4264 if (do_mark_object == G1MarkFromRoot) { 4265 mark_object(obj); 4266 } 4267 } 4268 4269 if (barrier == G1BarrierEvac) { 4270 _par_scan_state->update_rs(_from, p, _worker_id); 4271 } 4272 } 4273 4274 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p); 4275 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p); 4276 4277 class G1ParEvacuateFollowersClosure : public VoidClosure { 4278 protected: 4279 G1CollectedHeap* _g1h; 4280 G1ParScanThreadState* _par_scan_state; 4281 RefToScanQueueSet* _queues; 4282 ParallelTaskTerminator* _terminator; 4283 4284 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4285 RefToScanQueueSet* queues() { return _queues; } 4286 ParallelTaskTerminator* terminator() { return _terminator; } 4287 4288 public: 4289 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4290 G1ParScanThreadState* par_scan_state, 4291 RefToScanQueueSet* queues, 4292 ParallelTaskTerminator* terminator) 4293 : _g1h(g1h), _par_scan_state(par_scan_state), 4294 _queues(queues), _terminator(terminator) {} 4295 4296 void do_void(); 4297 4298 private: 4299 inline bool offer_termination(); 4300 }; 4301 4302 bool G1ParEvacuateFollowersClosure::offer_termination() { 4303 G1ParScanThreadState* const pss = par_scan_state(); 4304 pss->start_term_time(); 4305 const bool res = terminator()->offer_termination(); 4306 pss->end_term_time(); 4307 return res; 4308 } 4309 4310 void G1ParEvacuateFollowersClosure::do_void() { 4311 G1ParScanThreadState* const pss = par_scan_state(); 4312 pss->trim_queue(); 4313 do { 4314 pss->steal_and_trim_queue(queues()); 4315 } while (!offer_termination()); 4316 } 4317 4318 class G1KlassScanClosure : public KlassClosure { 4319 G1ParCopyHelper* _closure; 4320 bool _process_only_dirty; 4321 int _count; 4322 public: 4323 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4324 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4325 void do_klass(Klass* klass) { 4326 // If the klass has not been dirtied we know that there's 4327 // no references into the young gen and we can skip it. 4328 if (!_process_only_dirty || klass->has_modified_oops()) { 4329 // Clean the klass since we're going to scavenge all the metadata. 4330 klass->clear_modified_oops(); 4331 4332 // Tell the closure that this klass is the Klass to scavenge 4333 // and is the one to dirty if oops are left pointing into the young gen. 4334 _closure->set_scanned_klass(klass); 4335 4336 klass->oops_do(_closure); 4337 4338 _closure->set_scanned_klass(NULL); 4339 } 4340 _count++; 4341 } 4342 }; 4343 4344 class G1ParTask : public AbstractGangTask { 4345 protected: 4346 G1CollectedHeap* _g1h; 4347 RefToScanQueueSet *_queues; 4348 G1RootProcessor* _root_processor; 4349 ParallelTaskTerminator _terminator; 4350 uint _n_workers; 4351 4352 Mutex _stats_lock; 4353 Mutex* stats_lock() { return &_stats_lock; } 4354 4355 public: 4356 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor) 4357 : AbstractGangTask("G1 collection"), 4358 _g1h(g1h), 4359 _queues(task_queues), 4360 _root_processor(root_processor), 4361 _terminator(0, _queues), 4362 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4363 {} 4364 4365 RefToScanQueueSet* queues() { return _queues; } 4366 4367 RefToScanQueue *work_queue(int i) { 4368 return queues()->queue(i); 4369 } 4370 4371 ParallelTaskTerminator* terminator() { return &_terminator; } 4372 4373 virtual void set_for_termination(uint active_workers) { 4374 _root_processor->set_num_workers(active_workers); 4375 terminator()->reset_for_reuse(active_workers); 4376 _n_workers = active_workers; 4377 } 4378 4379 // Helps out with CLD processing. 4380 // 4381 // During InitialMark we need to: 4382 // 1) Scavenge all CLDs for the young GC. 4383 // 2) Mark all objects directly reachable from strong CLDs. 4384 template <G1Mark do_mark_object> 4385 class G1CLDClosure : public CLDClosure { 4386 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure; 4387 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure; 4388 G1KlassScanClosure _klass_in_cld_closure; 4389 bool _claim; 4390 4391 public: 4392 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure, 4393 bool only_young, bool claim) 4394 : _oop_closure(oop_closure), 4395 _oop_in_klass_closure(oop_closure->g1(), 4396 oop_closure->pss(), 4397 oop_closure->rp()), 4398 _klass_in_cld_closure(&_oop_in_klass_closure, only_young), 4399 _claim(claim) { 4400 4401 } 4402 4403 void do_cld(ClassLoaderData* cld) { 4404 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim); 4405 } 4406 }; 4407 4408 void work(uint worker_id) { 4409 if (worker_id >= _n_workers) return; // no work needed this round 4410 4411 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime()); 4412 4413 { 4414 ResourceMark rm; 4415 HandleMark hm; 4416 4417 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4418 4419 G1ParScanThreadState pss(_g1h, worker_id, rp); 4420 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 4421 4422 pss.set_evac_failure_closure(&evac_failure_cl); 4423 4424 bool only_young = _g1h->g1_policy()->gcs_are_young(); 4425 4426 // Non-IM young GC. 4427 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp); 4428 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl, 4429 only_young, // Only process dirty klasses. 4430 false); // No need to claim CLDs. 4431 // IM young GC. 4432 // Strong roots closures. 4433 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp); 4434 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl, 4435 false, // Process all klasses. 4436 true); // Need to claim CLDs. 4437 // Weak roots closures. 4438 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp); 4439 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl, 4440 false, // Process all klasses. 4441 true); // Need to claim CLDs. 4442 4443 OopClosure* strong_root_cl; 4444 OopClosure* weak_root_cl; 4445 CLDClosure* strong_cld_cl; 4446 CLDClosure* weak_cld_cl; 4447 4448 bool trace_metadata = false; 4449 4450 if (_g1h->g1_policy()->during_initial_mark_pause()) { 4451 // We also need to mark copied objects. 4452 strong_root_cl = &scan_mark_root_cl; 4453 strong_cld_cl = &scan_mark_cld_cl; 4454 if (ClassUnloadingWithConcurrentMark) { 4455 weak_root_cl = &scan_mark_weak_root_cl; 4456 weak_cld_cl = &scan_mark_weak_cld_cl; 4457 trace_metadata = true; 4458 } else { 4459 weak_root_cl = &scan_mark_root_cl; 4460 weak_cld_cl = &scan_mark_cld_cl; 4461 } 4462 } else { 4463 strong_root_cl = &scan_only_root_cl; 4464 weak_root_cl = &scan_only_root_cl; 4465 strong_cld_cl = &scan_only_cld_cl; 4466 weak_cld_cl = &scan_only_cld_cl; 4467 } 4468 4469 pss.start_strong_roots(); 4470 4471 _root_processor->evacuate_roots(strong_root_cl, 4472 weak_root_cl, 4473 strong_cld_cl, 4474 weak_cld_cl, 4475 trace_metadata, 4476 worker_id); 4477 4478 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4479 _root_processor->scan_remembered_sets(&push_heap_rs_cl, 4480 weak_root_cl, 4481 worker_id); 4482 pss.end_strong_roots(); 4483 4484 { 4485 double start = os::elapsedTime(); 4486 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4487 evac.do_void(); 4488 double elapsed_sec = os::elapsedTime() - start; 4489 double term_sec = pss.term_time(); 4490 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 4491 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 4492 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts()); 4493 } 4494 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4495 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4496 4497 if (PrintTerminationStats) { 4498 MutexLocker x(stats_lock()); 4499 pss.print_termination_stats(worker_id); 4500 } 4501 4502 assert(pss.queue_is_empty(), "should be empty"); 4503 4504 // Close the inner scope so that the ResourceMark and HandleMark 4505 // destructors are executed here and are included as part of the 4506 // "GC Worker Time". 4507 } 4508 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 4509 } 4510 }; 4511 4512 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4513 private: 4514 BoolObjectClosure* _is_alive; 4515 int _initial_string_table_size; 4516 int _initial_symbol_table_size; 4517 4518 bool _process_strings; 4519 int _strings_processed; 4520 int _strings_removed; 4521 4522 bool _process_symbols; 4523 int _symbols_processed; 4524 int _symbols_removed; 4525 4526 public: 4527 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4528 AbstractGangTask("String/Symbol Unlinking"), 4529 _is_alive(is_alive), 4530 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4531 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4532 4533 _initial_string_table_size = StringTable::the_table()->table_size(); 4534 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4535 if (process_strings) { 4536 StringTable::clear_parallel_claimed_index(); 4537 } 4538 if (process_symbols) { 4539 SymbolTable::clear_parallel_claimed_index(); 4540 } 4541 } 4542 4543 ~G1StringSymbolTableUnlinkTask() { 4544 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4545 err_msg("claim value %d after unlink less than initial string table size %d", 4546 StringTable::parallel_claimed_index(), _initial_string_table_size)); 4547 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4548 err_msg("claim value %d after unlink less than initial symbol table size %d", 4549 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 4550 4551 if (G1TraceStringSymbolTableScrubbing) { 4552 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4553 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 4554 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 4555 strings_processed(), strings_removed(), 4556 symbols_processed(), symbols_removed()); 4557 } 4558 } 4559 4560 void work(uint worker_id) { 4561 int strings_processed = 0; 4562 int strings_removed = 0; 4563 int symbols_processed = 0; 4564 int symbols_removed = 0; 4565 if (_process_strings) { 4566 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4567 Atomic::add(strings_processed, &_strings_processed); 4568 Atomic::add(strings_removed, &_strings_removed); 4569 } 4570 if (_process_symbols) { 4571 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 4572 Atomic::add(symbols_processed, &_symbols_processed); 4573 Atomic::add(symbols_removed, &_symbols_removed); 4574 } 4575 } 4576 4577 size_t strings_processed() const { return (size_t)_strings_processed; } 4578 size_t strings_removed() const { return (size_t)_strings_removed; } 4579 4580 size_t symbols_processed() const { return (size_t)_symbols_processed; } 4581 size_t symbols_removed() const { return (size_t)_symbols_removed; } 4582 }; 4583 4584 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 4585 private: 4586 static Monitor* _lock; 4587 4588 BoolObjectClosure* const _is_alive; 4589 const bool _unloading_occurred; 4590 const uint _num_workers; 4591 4592 // Variables used to claim nmethods. 4593 nmethod* _first_nmethod; 4594 volatile nmethod* _claimed_nmethod; 4595 4596 // The list of nmethods that need to be processed by the second pass. 4597 volatile nmethod* _postponed_list; 4598 volatile uint _num_entered_barrier; 4599 4600 public: 4601 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 4602 _is_alive(is_alive), 4603 _unloading_occurred(unloading_occurred), 4604 _num_workers(num_workers), 4605 _first_nmethod(NULL), 4606 _claimed_nmethod(NULL), 4607 _postponed_list(NULL), 4608 _num_entered_barrier(0) 4609 { 4610 nmethod::increase_unloading_clock(); 4611 // Get first alive nmethod 4612 NMethodIterator iter = NMethodIterator(); 4613 if(iter.next_alive()) { 4614 _first_nmethod = iter.method(); 4615 } 4616 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 4617 } 4618 4619 ~G1CodeCacheUnloadingTask() { 4620 CodeCache::verify_clean_inline_caches(); 4621 4622 CodeCache::set_needs_cache_clean(false); 4623 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 4624 4625 CodeCache::verify_icholder_relocations(); 4626 } 4627 4628 private: 4629 void add_to_postponed_list(nmethod* nm) { 4630 nmethod* old; 4631 do { 4632 old = (nmethod*)_postponed_list; 4633 nm->set_unloading_next(old); 4634 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 4635 } 4636 4637 void clean_nmethod(nmethod* nm) { 4638 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 4639 4640 if (postponed) { 4641 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 4642 add_to_postponed_list(nm); 4643 } 4644 4645 // Mark that this thread has been cleaned/unloaded. 4646 // After this call, it will be safe to ask if this nmethod was unloaded or not. 4647 nm->set_unloading_clock(nmethod::global_unloading_clock()); 4648 } 4649 4650 void clean_nmethod_postponed(nmethod* nm) { 4651 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 4652 } 4653 4654 static const int MaxClaimNmethods = 16; 4655 4656 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 4657 nmethod* first; 4658 NMethodIterator last; 4659 4660 do { 4661 *num_claimed_nmethods = 0; 4662 4663 first = (nmethod*)_claimed_nmethod; 4664 last = NMethodIterator(first); 4665 4666 if (first != NULL) { 4667 4668 for (int i = 0; i < MaxClaimNmethods; i++) { 4669 if (!last.next_alive()) { 4670 break; 4671 } 4672 claimed_nmethods[i] = last.method(); 4673 (*num_claimed_nmethods)++; 4674 } 4675 } 4676 4677 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 4678 } 4679 4680 nmethod* claim_postponed_nmethod() { 4681 nmethod* claim; 4682 nmethod* next; 4683 4684 do { 4685 claim = (nmethod*)_postponed_list; 4686 if (claim == NULL) { 4687 return NULL; 4688 } 4689 4690 next = claim->unloading_next(); 4691 4692 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 4693 4694 return claim; 4695 } 4696 4697 public: 4698 // Mark that we're done with the first pass of nmethod cleaning. 4699 void barrier_mark(uint worker_id) { 4700 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4701 _num_entered_barrier++; 4702 if (_num_entered_barrier == _num_workers) { 4703 ml.notify_all(); 4704 } 4705 } 4706 4707 // See if we have to wait for the other workers to 4708 // finish their first-pass nmethod cleaning work. 4709 void barrier_wait(uint worker_id) { 4710 if (_num_entered_barrier < _num_workers) { 4711 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4712 while (_num_entered_barrier < _num_workers) { 4713 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 4714 } 4715 } 4716 } 4717 4718 // Cleaning and unloading of nmethods. Some work has to be postponed 4719 // to the second pass, when we know which nmethods survive. 4720 void work_first_pass(uint worker_id) { 4721 // The first nmethods is claimed by the first worker. 4722 if (worker_id == 0 && _first_nmethod != NULL) { 4723 clean_nmethod(_first_nmethod); 4724 _first_nmethod = NULL; 4725 } 4726 4727 int num_claimed_nmethods; 4728 nmethod* claimed_nmethods[MaxClaimNmethods]; 4729 4730 while (true) { 4731 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 4732 4733 if (num_claimed_nmethods == 0) { 4734 break; 4735 } 4736 4737 for (int i = 0; i < num_claimed_nmethods; i++) { 4738 clean_nmethod(claimed_nmethods[i]); 4739 } 4740 } 4741 } 4742 4743 void work_second_pass(uint worker_id) { 4744 nmethod* nm; 4745 // Take care of postponed nmethods. 4746 while ((nm = claim_postponed_nmethod()) != NULL) { 4747 clean_nmethod_postponed(nm); 4748 } 4749 } 4750 }; 4751 4752 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 4753 4754 class G1KlassCleaningTask : public StackObj { 4755 BoolObjectClosure* _is_alive; 4756 volatile jint _clean_klass_tree_claimed; 4757 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 4758 4759 public: 4760 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 4761 _is_alive(is_alive), 4762 _clean_klass_tree_claimed(0), 4763 _klass_iterator() { 4764 } 4765 4766 private: 4767 bool claim_clean_klass_tree_task() { 4768 if (_clean_klass_tree_claimed) { 4769 return false; 4770 } 4771 4772 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 4773 } 4774 4775 InstanceKlass* claim_next_klass() { 4776 Klass* klass; 4777 do { 4778 klass =_klass_iterator.next_klass(); 4779 } while (klass != NULL && !klass->oop_is_instance()); 4780 4781 return (InstanceKlass*)klass; 4782 } 4783 4784 public: 4785 4786 void clean_klass(InstanceKlass* ik) { 4787 ik->clean_implementors_list(_is_alive); 4788 ik->clean_method_data(_is_alive); 4789 4790 // G1 specific cleanup work that has 4791 // been moved here to be done in parallel. 4792 ik->clean_dependent_nmethods(); 4793 } 4794 4795 void work() { 4796 ResourceMark rm; 4797 4798 // One worker will clean the subklass/sibling klass tree. 4799 if (claim_clean_klass_tree_task()) { 4800 Klass::clean_subklass_tree(_is_alive); 4801 } 4802 4803 // All workers will help cleaning the classes, 4804 InstanceKlass* klass; 4805 while ((klass = claim_next_klass()) != NULL) { 4806 clean_klass(klass); 4807 } 4808 } 4809 }; 4810 4811 // To minimize the remark pause times, the tasks below are done in parallel. 4812 class G1ParallelCleaningTask : public AbstractGangTask { 4813 private: 4814 G1StringSymbolTableUnlinkTask _string_symbol_task; 4815 G1CodeCacheUnloadingTask _code_cache_task; 4816 G1KlassCleaningTask _klass_cleaning_task; 4817 4818 public: 4819 // The constructor is run in the VMThread. 4820 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 4821 AbstractGangTask("Parallel Cleaning"), 4822 _string_symbol_task(is_alive, process_strings, process_symbols), 4823 _code_cache_task(num_workers, is_alive, unloading_occurred), 4824 _klass_cleaning_task(is_alive) { 4825 } 4826 4827 // The parallel work done by all worker threads. 4828 void work(uint worker_id) { 4829 // Do first pass of code cache cleaning. 4830 _code_cache_task.work_first_pass(worker_id); 4831 4832 // Let the threads mark that the first pass is done. 4833 _code_cache_task.barrier_mark(worker_id); 4834 4835 // Clean the Strings and Symbols. 4836 _string_symbol_task.work(worker_id); 4837 4838 // Wait for all workers to finish the first code cache cleaning pass. 4839 _code_cache_task.barrier_wait(worker_id); 4840 4841 // Do the second code cache cleaning work, which realize on 4842 // the liveness information gathered during the first pass. 4843 _code_cache_task.work_second_pass(worker_id); 4844 4845 // Clean all klasses that were not unloaded. 4846 _klass_cleaning_task.work(); 4847 } 4848 }; 4849 4850 4851 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 4852 bool process_strings, 4853 bool process_symbols, 4854 bool class_unloading_occurred) { 4855 uint n_workers = workers()->active_workers(); 4856 4857 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 4858 n_workers, class_unloading_occurred); 4859 set_par_threads(n_workers); 4860 workers()->run_task(&g1_unlink_task); 4861 set_par_threads(0); 4862 } 4863 4864 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 4865 bool process_strings, bool process_symbols) { 4866 { 4867 uint n_workers = workers()->active_workers(); 4868 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 4869 set_par_threads(n_workers); 4870 workers()->run_task(&g1_unlink_task); 4871 set_par_threads(0); 4872 } 4873 4874 if (G1StringDedup::is_enabled()) { 4875 G1StringDedup::unlink(is_alive); 4876 } 4877 } 4878 4879 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 4880 private: 4881 DirtyCardQueueSet* _queue; 4882 public: 4883 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 4884 4885 virtual void work(uint worker_id) { 4886 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4887 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 4888 4889 RedirtyLoggedCardTableEntryClosure cl; 4890 _queue->par_apply_closure_to_all_completed_buffers(&cl); 4891 4892 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed()); 4893 } 4894 }; 4895 4896 void G1CollectedHeap::redirty_logged_cards() { 4897 double redirty_logged_cards_start = os::elapsedTime(); 4898 4899 uint n_workers = workers()->active_workers(); 4900 4901 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 4902 dirty_card_queue_set().reset_for_par_iteration(); 4903 set_par_threads(n_workers); 4904 workers()->run_task(&redirty_task); 4905 set_par_threads(0); 4906 4907 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 4908 dcq.merge_bufferlists(&dirty_card_queue_set()); 4909 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 4910 4911 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 4912 } 4913 4914 // Weak Reference Processing support 4915 4916 // An always "is_alive" closure that is used to preserve referents. 4917 // If the object is non-null then it's alive. Used in the preservation 4918 // of referent objects that are pointed to by reference objects 4919 // discovered by the CM ref processor. 4920 class G1AlwaysAliveClosure: public BoolObjectClosure { 4921 G1CollectedHeap* _g1; 4922 public: 4923 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4924 bool do_object_b(oop p) { 4925 if (p != NULL) { 4926 return true; 4927 } 4928 return false; 4929 } 4930 }; 4931 4932 bool G1STWIsAliveClosure::do_object_b(oop p) { 4933 // An object is reachable if it is outside the collection set, 4934 // or is inside and copied. 4935 return !_g1->obj_in_cs(p) || p->is_forwarded(); 4936 } 4937 4938 // Non Copying Keep Alive closure 4939 class G1KeepAliveClosure: public OopClosure { 4940 G1CollectedHeap* _g1; 4941 public: 4942 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4943 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 4944 void do_oop(oop* p) { 4945 oop obj = *p; 4946 assert(obj != NULL, "the caller should have filtered out NULL values"); 4947 4948 const InCSetState cset_state = _g1->in_cset_state(obj); 4949 if (!cset_state.is_in_cset_or_humongous()) { 4950 return; 4951 } 4952 if (cset_state.is_in_cset()) { 4953 assert( obj->is_forwarded(), "invariant" ); 4954 *p = obj->forwardee(); 4955 } else { 4956 assert(!obj->is_forwarded(), "invariant" ); 4957 assert(cset_state.is_humongous(), 4958 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value())); 4959 _g1->set_humongous_is_live(obj); 4960 } 4961 } 4962 }; 4963 4964 // Copying Keep Alive closure - can be called from both 4965 // serial and parallel code as long as different worker 4966 // threads utilize different G1ParScanThreadState instances 4967 // and different queues. 4968 4969 class G1CopyingKeepAliveClosure: public OopClosure { 4970 G1CollectedHeap* _g1h; 4971 OopClosure* _copy_non_heap_obj_cl; 4972 G1ParScanThreadState* _par_scan_state; 4973 4974 public: 4975 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 4976 OopClosure* non_heap_obj_cl, 4977 G1ParScanThreadState* pss): 4978 _g1h(g1h), 4979 _copy_non_heap_obj_cl(non_heap_obj_cl), 4980 _par_scan_state(pss) 4981 {} 4982 4983 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 4984 virtual void do_oop( oop* p) { do_oop_work(p); } 4985 4986 template <class T> void do_oop_work(T* p) { 4987 oop obj = oopDesc::load_decode_heap_oop(p); 4988 4989 if (_g1h->is_in_cset_or_humongous(obj)) { 4990 // If the referent object has been forwarded (either copied 4991 // to a new location or to itself in the event of an 4992 // evacuation failure) then we need to update the reference 4993 // field and, if both reference and referent are in the G1 4994 // heap, update the RSet for the referent. 4995 // 4996 // If the referent has not been forwarded then we have to keep 4997 // it alive by policy. Therefore we have copy the referent. 4998 // 4999 // If the reference field is in the G1 heap then we can push 5000 // on the PSS queue. When the queue is drained (after each 5001 // phase of reference processing) the object and it's followers 5002 // will be copied, the reference field set to point to the 5003 // new location, and the RSet updated. Otherwise we need to 5004 // use the the non-heap or metadata closures directly to copy 5005 // the referent object and update the pointer, while avoiding 5006 // updating the RSet. 5007 5008 if (_g1h->is_in_g1_reserved(p)) { 5009 _par_scan_state->push_on_queue(p); 5010 } else { 5011 assert(!Metaspace::contains((const void*)p), 5012 err_msg("Unexpectedly found a pointer from metadata: " 5013 PTR_FORMAT, p)); 5014 _copy_non_heap_obj_cl->do_oop(p); 5015 } 5016 } 5017 } 5018 }; 5019 5020 // Serial drain queue closure. Called as the 'complete_gc' 5021 // closure for each discovered list in some of the 5022 // reference processing phases. 5023 5024 class G1STWDrainQueueClosure: public VoidClosure { 5025 protected: 5026 G1CollectedHeap* _g1h; 5027 G1ParScanThreadState* _par_scan_state; 5028 5029 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5030 5031 public: 5032 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5033 _g1h(g1h), 5034 _par_scan_state(pss) 5035 { } 5036 5037 void do_void() { 5038 G1ParScanThreadState* const pss = par_scan_state(); 5039 pss->trim_queue(); 5040 } 5041 }; 5042 5043 // Parallel Reference Processing closures 5044 5045 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5046 // processing during G1 evacuation pauses. 5047 5048 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5049 private: 5050 G1CollectedHeap* _g1h; 5051 RefToScanQueueSet* _queues; 5052 FlexibleWorkGang* _workers; 5053 uint _active_workers; 5054 5055 public: 5056 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5057 FlexibleWorkGang* workers, 5058 RefToScanQueueSet *task_queues, 5059 uint n_workers) : 5060 _g1h(g1h), 5061 _queues(task_queues), 5062 _workers(workers), 5063 _active_workers(n_workers) 5064 { 5065 assert(n_workers > 0, "shouldn't call this otherwise"); 5066 } 5067 5068 // Executes the given task using concurrent marking worker threads. 5069 virtual void execute(ProcessTask& task); 5070 virtual void execute(EnqueueTask& task); 5071 }; 5072 5073 // Gang task for possibly parallel reference processing 5074 5075 class G1STWRefProcTaskProxy: public AbstractGangTask { 5076 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5077 ProcessTask& _proc_task; 5078 G1CollectedHeap* _g1h; 5079 RefToScanQueueSet *_task_queues; 5080 ParallelTaskTerminator* _terminator; 5081 5082 public: 5083 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5084 G1CollectedHeap* g1h, 5085 RefToScanQueueSet *task_queues, 5086 ParallelTaskTerminator* terminator) : 5087 AbstractGangTask("Process reference objects in parallel"), 5088 _proc_task(proc_task), 5089 _g1h(g1h), 5090 _task_queues(task_queues), 5091 _terminator(terminator) 5092 {} 5093 5094 virtual void work(uint worker_id) { 5095 // The reference processing task executed by a single worker. 5096 ResourceMark rm; 5097 HandleMark hm; 5098 5099 G1STWIsAliveClosure is_alive(_g1h); 5100 5101 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5102 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5103 5104 pss.set_evac_failure_closure(&evac_failure_cl); 5105 5106 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5107 5108 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5109 5110 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5111 5112 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5113 // We also need to mark copied objects. 5114 copy_non_heap_cl = ©_mark_non_heap_cl; 5115 } 5116 5117 // Keep alive closure. 5118 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5119 5120 // Complete GC closure 5121 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5122 5123 // Call the reference processing task's work routine. 5124 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5125 5126 // Note we cannot assert that the refs array is empty here as not all 5127 // of the processing tasks (specifically phase2 - pp2_work) execute 5128 // the complete_gc closure (which ordinarily would drain the queue) so 5129 // the queue may not be empty. 5130 } 5131 }; 5132 5133 // Driver routine for parallel reference processing. 5134 // Creates an instance of the ref processing gang 5135 // task and has the worker threads execute it. 5136 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5137 assert(_workers != NULL, "Need parallel worker threads."); 5138 5139 ParallelTaskTerminator terminator(_active_workers, _queues); 5140 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5141 5142 _g1h->set_par_threads(_active_workers); 5143 _workers->run_task(&proc_task_proxy); 5144 _g1h->set_par_threads(0); 5145 } 5146 5147 // Gang task for parallel reference enqueueing. 5148 5149 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5150 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5151 EnqueueTask& _enq_task; 5152 5153 public: 5154 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5155 AbstractGangTask("Enqueue reference objects in parallel"), 5156 _enq_task(enq_task) 5157 { } 5158 5159 virtual void work(uint worker_id) { 5160 _enq_task.work(worker_id); 5161 } 5162 }; 5163 5164 // Driver routine for parallel reference enqueueing. 5165 // Creates an instance of the ref enqueueing gang 5166 // task and has the worker threads execute it. 5167 5168 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5169 assert(_workers != NULL, "Need parallel worker threads."); 5170 5171 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5172 5173 _g1h->set_par_threads(_active_workers); 5174 _workers->run_task(&enq_task_proxy); 5175 _g1h->set_par_threads(0); 5176 } 5177 5178 // End of weak reference support closures 5179 5180 // Abstract task used to preserve (i.e. copy) any referent objects 5181 // that are in the collection set and are pointed to by reference 5182 // objects discovered by the CM ref processor. 5183 5184 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5185 protected: 5186 G1CollectedHeap* _g1h; 5187 RefToScanQueueSet *_queues; 5188 ParallelTaskTerminator _terminator; 5189 uint _n_workers; 5190 5191 public: 5192 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, uint workers, RefToScanQueueSet *task_queues) : 5193 AbstractGangTask("ParPreserveCMReferents"), 5194 _g1h(g1h), 5195 _queues(task_queues), 5196 _terminator(workers, _queues), 5197 _n_workers(workers) 5198 { } 5199 5200 void work(uint worker_id) { 5201 ResourceMark rm; 5202 HandleMark hm; 5203 5204 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5205 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5206 5207 pss.set_evac_failure_closure(&evac_failure_cl); 5208 5209 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5210 5211 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5212 5213 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5214 5215 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5216 5217 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5218 // We also need to mark copied objects. 5219 copy_non_heap_cl = ©_mark_non_heap_cl; 5220 } 5221 5222 // Is alive closure 5223 G1AlwaysAliveClosure always_alive(_g1h); 5224 5225 // Copying keep alive closure. Applied to referent objects that need 5226 // to be copied. 5227 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5228 5229 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5230 5231 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5232 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5233 5234 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5235 // So this must be true - but assert just in case someone decides to 5236 // change the worker ids. 5237 assert(worker_id < limit, "sanity"); 5238 assert(!rp->discovery_is_atomic(), "check this code"); 5239 5240 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5241 for (uint idx = worker_id; idx < limit; idx += stride) { 5242 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5243 5244 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5245 while (iter.has_next()) { 5246 // Since discovery is not atomic for the CM ref processor, we 5247 // can see some null referent objects. 5248 iter.load_ptrs(DEBUG_ONLY(true)); 5249 oop ref = iter.obj(); 5250 5251 // This will filter nulls. 5252 if (iter.is_referent_alive()) { 5253 iter.make_referent_alive(); 5254 } 5255 iter.move_to_next(); 5256 } 5257 } 5258 5259 // Drain the queue - which may cause stealing 5260 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5261 drain_queue.do_void(); 5262 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5263 assert(pss.queue_is_empty(), "should be"); 5264 } 5265 }; 5266 5267 // Weak Reference processing during an evacuation pause (part 1). 5268 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5269 double ref_proc_start = os::elapsedTime(); 5270 5271 ReferenceProcessor* rp = _ref_processor_stw; 5272 assert(rp->discovery_enabled(), "should have been enabled"); 5273 5274 // Any reference objects, in the collection set, that were 'discovered' 5275 // by the CM ref processor should have already been copied (either by 5276 // applying the external root copy closure to the discovered lists, or 5277 // by following an RSet entry). 5278 // 5279 // But some of the referents, that are in the collection set, that these 5280 // reference objects point to may not have been copied: the STW ref 5281 // processor would have seen that the reference object had already 5282 // been 'discovered' and would have skipped discovering the reference, 5283 // but would not have treated the reference object as a regular oop. 5284 // As a result the copy closure would not have been applied to the 5285 // referent object. 5286 // 5287 // We need to explicitly copy these referent objects - the references 5288 // will be processed at the end of remarking. 5289 // 5290 // We also need to do this copying before we process the reference 5291 // objects discovered by the STW ref processor in case one of these 5292 // referents points to another object which is also referenced by an 5293 // object discovered by the STW ref processor. 5294 5295 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers"); 5296 5297 set_par_threads(no_of_gc_workers); 5298 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5299 no_of_gc_workers, 5300 _task_queues); 5301 5302 workers()->run_task(&keep_cm_referents); 5303 5304 set_par_threads(0); 5305 5306 // Closure to test whether a referent is alive. 5307 G1STWIsAliveClosure is_alive(this); 5308 5309 // Even when parallel reference processing is enabled, the processing 5310 // of JNI refs is serial and performed serially by the current thread 5311 // rather than by a worker. The following PSS will be used for processing 5312 // JNI refs. 5313 5314 // Use only a single queue for this PSS. 5315 G1ParScanThreadState pss(this, 0, NULL); 5316 5317 // We do not embed a reference processor in the copying/scanning 5318 // closures while we're actually processing the discovered 5319 // reference objects. 5320 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5321 5322 pss.set_evac_failure_closure(&evac_failure_cl); 5323 5324 assert(pss.queue_is_empty(), "pre-condition"); 5325 5326 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5327 5328 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5329 5330 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5331 5332 if (g1_policy()->during_initial_mark_pause()) { 5333 // We also need to mark copied objects. 5334 copy_non_heap_cl = ©_mark_non_heap_cl; 5335 } 5336 5337 // Keep alive closure. 5338 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss); 5339 5340 // Serial Complete GC closure 5341 G1STWDrainQueueClosure drain_queue(this, &pss); 5342 5343 // Setup the soft refs policy... 5344 rp->setup_policy(false); 5345 5346 ReferenceProcessorStats stats; 5347 if (!rp->processing_is_mt()) { 5348 // Serial reference processing... 5349 stats = rp->process_discovered_references(&is_alive, 5350 &keep_alive, 5351 &drain_queue, 5352 NULL, 5353 _gc_timer_stw, 5354 _gc_tracer_stw->gc_id()); 5355 } else { 5356 // Parallel reference processing 5357 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5358 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5359 5360 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5361 stats = rp->process_discovered_references(&is_alive, 5362 &keep_alive, 5363 &drain_queue, 5364 &par_task_executor, 5365 _gc_timer_stw, 5366 _gc_tracer_stw->gc_id()); 5367 } 5368 5369 _gc_tracer_stw->report_gc_reference_stats(stats); 5370 5371 // We have completed copying any necessary live referent objects. 5372 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5373 5374 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5375 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5376 } 5377 5378 // Weak Reference processing during an evacuation pause (part 2). 5379 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5380 double ref_enq_start = os::elapsedTime(); 5381 5382 ReferenceProcessor* rp = _ref_processor_stw; 5383 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5384 5385 // Now enqueue any remaining on the discovered lists on to 5386 // the pending list. 5387 if (!rp->processing_is_mt()) { 5388 // Serial reference processing... 5389 rp->enqueue_discovered_references(); 5390 } else { 5391 // Parallel reference enqueueing 5392 5393 assert(no_of_gc_workers == workers()->active_workers(), 5394 "Need to reset active workers"); 5395 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5396 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5397 5398 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5399 rp->enqueue_discovered_references(&par_task_executor); 5400 } 5401 5402 rp->verify_no_references_recorded(); 5403 assert(!rp->discovery_enabled(), "should have been disabled"); 5404 5405 // FIXME 5406 // CM's reference processing also cleans up the string and symbol tables. 5407 // Should we do that here also? We could, but it is a serial operation 5408 // and could significantly increase the pause time. 5409 5410 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5411 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5412 } 5413 5414 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5415 _expand_heap_after_alloc_failure = true; 5416 _evacuation_failed = false; 5417 5418 // Should G1EvacuationFailureALot be in effect for this GC? 5419 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5420 5421 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5422 5423 // Disable the hot card cache. 5424 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5425 hot_card_cache->reset_hot_cache_claimed_index(); 5426 hot_card_cache->set_use_cache(false); 5427 5428 const uint n_workers = workers()->active_workers(); 5429 assert(UseDynamicNumberOfGCThreads || 5430 n_workers == workers()->total_workers(), 5431 "If not dynamic should be using all the workers"); 5432 set_par_threads(n_workers); 5433 5434 5435 init_for_evac_failure(NULL); 5436 5437 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5438 double start_par_time_sec = os::elapsedTime(); 5439 double end_par_time_sec; 5440 5441 { 5442 G1RootProcessor root_processor(this); 5443 G1ParTask g1_par_task(this, _task_queues, &root_processor); 5444 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5445 if (g1_policy()->during_initial_mark_pause()) { 5446 ClassLoaderDataGraph::clear_claimed_marks(); 5447 } 5448 5449 // The individual threads will set their evac-failure closures. 5450 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr(); 5451 // These tasks use ShareHeap::_process_strong_tasks 5452 assert(UseDynamicNumberOfGCThreads || 5453 workers()->active_workers() == workers()->total_workers(), 5454 "If not dynamic should be using all the workers"); 5455 workers()->run_task(&g1_par_task); 5456 end_par_time_sec = os::elapsedTime(); 5457 5458 // Closing the inner scope will execute the destructor 5459 // for the G1RootProcessor object. We record the current 5460 // elapsed time before closing the scope so that time 5461 // taken for the destructor is NOT included in the 5462 // reported parallel time. 5463 } 5464 5465 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 5466 5467 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5468 phase_times->record_par_time(par_time_ms); 5469 5470 double code_root_fixup_time_ms = 5471 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5472 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 5473 5474 set_par_threads(0); 5475 5476 // Process any discovered reference objects - we have 5477 // to do this _before_ we retire the GC alloc regions 5478 // as we may have to copy some 'reachable' referent 5479 // objects (and their reachable sub-graphs) that were 5480 // not copied during the pause. 5481 process_discovered_references(n_workers); 5482 5483 if (G1StringDedup::is_enabled()) { 5484 double fixup_start = os::elapsedTime(); 5485 5486 G1STWIsAliveClosure is_alive(this); 5487 G1KeepAliveClosure keep_alive(this); 5488 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times); 5489 5490 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 5491 phase_times->record_string_dedup_fixup_time(fixup_time_ms); 5492 } 5493 5494 _allocator->release_gc_alloc_regions(n_workers, evacuation_info); 5495 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5496 5497 // Reset and re-enable the hot card cache. 5498 // Note the counts for the cards in the regions in the 5499 // collection set are reset when the collection set is freed. 5500 hot_card_cache->reset_hot_cache(); 5501 hot_card_cache->set_use_cache(true); 5502 5503 purge_code_root_memory(); 5504 5505 finalize_for_evac_failure(); 5506 5507 if (evacuation_failed()) { 5508 remove_self_forwarding_pointers(); 5509 5510 // Reset the G1EvacuationFailureALot counters and flags 5511 // Note: the values are reset only when an actual 5512 // evacuation failure occurs. 5513 NOT_PRODUCT(reset_evacuation_should_fail();) 5514 } 5515 5516 // Enqueue any remaining references remaining on the STW 5517 // reference processor's discovered lists. We need to do 5518 // this after the card table is cleaned (and verified) as 5519 // the act of enqueueing entries on to the pending list 5520 // will log these updates (and dirty their associated 5521 // cards). We need these updates logged to update any 5522 // RSets. 5523 enqueue_discovered_references(n_workers); 5524 5525 redirty_logged_cards(); 5526 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5527 } 5528 5529 void G1CollectedHeap::free_region(HeapRegion* hr, 5530 FreeRegionList* free_list, 5531 bool par, 5532 bool locked) { 5533 assert(!hr->is_free(), "the region should not be free"); 5534 assert(!hr->is_empty(), "the region should not be empty"); 5535 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 5536 assert(free_list != NULL, "pre-condition"); 5537 5538 if (G1VerifyBitmaps) { 5539 MemRegion mr(hr->bottom(), hr->end()); 5540 concurrent_mark()->clearRangePrevBitmap(mr); 5541 } 5542 5543 // Clear the card counts for this region. 5544 // Note: we only need to do this if the region is not young 5545 // (since we don't refine cards in young regions). 5546 if (!hr->is_young()) { 5547 _cg1r->hot_card_cache()->reset_card_counts(hr); 5548 } 5549 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5550 free_list->add_ordered(hr); 5551 } 5552 5553 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5554 FreeRegionList* free_list, 5555 bool par) { 5556 assert(hr->is_starts_humongous(), "this is only for starts humongous regions"); 5557 assert(free_list != NULL, "pre-condition"); 5558 5559 size_t hr_capacity = hr->capacity(); 5560 // We need to read this before we make the region non-humongous, 5561 // otherwise the information will be gone. 5562 uint last_index = hr->last_hc_index(); 5563 hr->clear_humongous(); 5564 free_region(hr, free_list, par); 5565 5566 uint i = hr->hrm_index() + 1; 5567 while (i < last_index) { 5568 HeapRegion* curr_hr = region_at(i); 5569 assert(curr_hr->is_continues_humongous(), "invariant"); 5570 curr_hr->clear_humongous(); 5571 free_region(curr_hr, free_list, par); 5572 i += 1; 5573 } 5574 } 5575 5576 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 5577 const HeapRegionSetCount& humongous_regions_removed) { 5578 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5579 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5580 _old_set.bulk_remove(old_regions_removed); 5581 _humongous_set.bulk_remove(humongous_regions_removed); 5582 } 5583 5584 } 5585 5586 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 5587 assert(list != NULL, "list can't be null"); 5588 if (!list->is_empty()) { 5589 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5590 _hrm.insert_list_into_free_list(list); 5591 } 5592 } 5593 5594 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 5595 _allocator->decrease_used(bytes); 5596 } 5597 5598 class G1ParCleanupCTTask : public AbstractGangTask { 5599 G1SATBCardTableModRefBS* _ct_bs; 5600 G1CollectedHeap* _g1h; 5601 HeapRegion* volatile _su_head; 5602 public: 5603 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 5604 G1CollectedHeap* g1h) : 5605 AbstractGangTask("G1 Par Cleanup CT Task"), 5606 _ct_bs(ct_bs), _g1h(g1h) { } 5607 5608 void work(uint worker_id) { 5609 HeapRegion* r; 5610 while (r = _g1h->pop_dirty_cards_region()) { 5611 clear_cards(r); 5612 } 5613 } 5614 5615 void clear_cards(HeapRegion* r) { 5616 // Cards of the survivors should have already been dirtied. 5617 if (!r->is_survivor()) { 5618 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5619 } 5620 } 5621 }; 5622 5623 #ifndef PRODUCT 5624 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5625 G1CollectedHeap* _g1h; 5626 G1SATBCardTableModRefBS* _ct_bs; 5627 public: 5628 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 5629 : _g1h(g1h), _ct_bs(ct_bs) { } 5630 virtual bool doHeapRegion(HeapRegion* r) { 5631 if (r->is_survivor()) { 5632 _g1h->verify_dirty_region(r); 5633 } else { 5634 _g1h->verify_not_dirty_region(r); 5635 } 5636 return false; 5637 } 5638 }; 5639 5640 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5641 // All of the region should be clean. 5642 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5643 MemRegion mr(hr->bottom(), hr->end()); 5644 ct_bs->verify_not_dirty_region(mr); 5645 } 5646 5647 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5648 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5649 // dirty allocated blocks as they allocate them. The thread that 5650 // retires each region and replaces it with a new one will do a 5651 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5652 // not dirty that area (one less thing to have to do while holding 5653 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5654 // is dirty. 5655 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5656 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5657 if (hr->is_young()) { 5658 ct_bs->verify_g1_young_region(mr); 5659 } else { 5660 ct_bs->verify_dirty_region(mr); 5661 } 5662 } 5663 5664 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5665 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5666 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5667 verify_dirty_region(hr); 5668 } 5669 } 5670 5671 void G1CollectedHeap::verify_dirty_young_regions() { 5672 verify_dirty_young_list(_young_list->first_region()); 5673 } 5674 5675 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 5676 HeapWord* tams, HeapWord* end) { 5677 guarantee(tams <= end, 5678 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end)); 5679 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 5680 if (result < end) { 5681 gclog_or_tty->cr(); 5682 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT, 5683 bitmap_name, result); 5684 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT, 5685 bitmap_name, tams, end); 5686 return false; 5687 } 5688 return true; 5689 } 5690 5691 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 5692 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 5693 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 5694 5695 HeapWord* bottom = hr->bottom(); 5696 HeapWord* ptams = hr->prev_top_at_mark_start(); 5697 HeapWord* ntams = hr->next_top_at_mark_start(); 5698 HeapWord* end = hr->end(); 5699 5700 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 5701 5702 bool res_n = true; 5703 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 5704 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 5705 // if we happen to be in that state. 5706 if (mark_in_progress() || !_cmThread->in_progress()) { 5707 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 5708 } 5709 if (!res_p || !res_n) { 5710 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT, 5711 HR_FORMAT_PARAMS(hr)); 5712 gclog_or_tty->print_cr("#### Caller: %s", caller); 5713 return false; 5714 } 5715 return true; 5716 } 5717 5718 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 5719 if (!G1VerifyBitmaps) return; 5720 5721 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 5722 } 5723 5724 class G1VerifyBitmapClosure : public HeapRegionClosure { 5725 private: 5726 const char* _caller; 5727 G1CollectedHeap* _g1h; 5728 bool _failures; 5729 5730 public: 5731 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 5732 _caller(caller), _g1h(g1h), _failures(false) { } 5733 5734 bool failures() { return _failures; } 5735 5736 virtual bool doHeapRegion(HeapRegion* hr) { 5737 if (hr->is_continues_humongous()) return false; 5738 5739 bool result = _g1h->verify_bitmaps(_caller, hr); 5740 if (!result) { 5741 _failures = true; 5742 } 5743 return false; 5744 } 5745 }; 5746 5747 void G1CollectedHeap::check_bitmaps(const char* caller) { 5748 if (!G1VerifyBitmaps) return; 5749 5750 G1VerifyBitmapClosure cl(caller, this); 5751 heap_region_iterate(&cl); 5752 guarantee(!cl.failures(), "bitmap verification"); 5753 } 5754 5755 class G1CheckCSetFastTableClosure : public HeapRegionClosure { 5756 private: 5757 bool _failures; 5758 public: 5759 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { } 5760 5761 virtual bool doHeapRegion(HeapRegion* hr) { 5762 uint i = hr->hrm_index(); 5763 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i); 5764 if (hr->is_humongous()) { 5765 if (hr->in_collection_set()) { 5766 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i); 5767 _failures = true; 5768 return true; 5769 } 5770 if (cset_state.is_in_cset()) { 5771 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i); 5772 _failures = true; 5773 return true; 5774 } 5775 if (hr->is_continues_humongous() && cset_state.is_humongous()) { 5776 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i); 5777 _failures = true; 5778 return true; 5779 } 5780 } else { 5781 if (cset_state.is_humongous()) { 5782 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i); 5783 _failures = true; 5784 return true; 5785 } 5786 if (hr->in_collection_set() != cset_state.is_in_cset()) { 5787 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u", 5788 hr->in_collection_set(), cset_state.value(), i); 5789 _failures = true; 5790 return true; 5791 } 5792 if (cset_state.is_in_cset()) { 5793 if (hr->is_young() != (cset_state.is_young())) { 5794 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u", 5795 hr->is_young(), cset_state.value(), i); 5796 _failures = true; 5797 return true; 5798 } 5799 if (hr->is_old() != (cset_state.is_old())) { 5800 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u", 5801 hr->is_old(), cset_state.value(), i); 5802 _failures = true; 5803 return true; 5804 } 5805 } 5806 } 5807 return false; 5808 } 5809 5810 bool failures() const { return _failures; } 5811 }; 5812 5813 bool G1CollectedHeap::check_cset_fast_test() { 5814 G1CheckCSetFastTableClosure cl; 5815 _hrm.iterate(&cl); 5816 return !cl.failures(); 5817 } 5818 #endif // PRODUCT 5819 5820 void G1CollectedHeap::cleanUpCardTable() { 5821 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5822 double start = os::elapsedTime(); 5823 5824 { 5825 // Iterate over the dirty cards region list. 5826 G1ParCleanupCTTask cleanup_task(ct_bs, this); 5827 5828 set_par_threads(); 5829 workers()->run_task(&cleanup_task); 5830 set_par_threads(0); 5831 #ifndef PRODUCT 5832 if (G1VerifyCTCleanup || VerifyAfterGC) { 5833 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 5834 heap_region_iterate(&cleanup_verifier); 5835 } 5836 #endif 5837 } 5838 5839 double elapsed = os::elapsedTime() - start; 5840 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 5841 } 5842 5843 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 5844 size_t pre_used = 0; 5845 FreeRegionList local_free_list("Local List for CSet Freeing"); 5846 5847 double young_time_ms = 0.0; 5848 double non_young_time_ms = 0.0; 5849 5850 // Since the collection set is a superset of the the young list, 5851 // all we need to do to clear the young list is clear its 5852 // head and length, and unlink any young regions in the code below 5853 _young_list->clear(); 5854 5855 G1CollectorPolicy* policy = g1_policy(); 5856 5857 double start_sec = os::elapsedTime(); 5858 bool non_young = true; 5859 5860 HeapRegion* cur = cs_head; 5861 int age_bound = -1; 5862 size_t rs_lengths = 0; 5863 5864 while (cur != NULL) { 5865 assert(!is_on_master_free_list(cur), "sanity"); 5866 if (non_young) { 5867 if (cur->is_young()) { 5868 double end_sec = os::elapsedTime(); 5869 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5870 non_young_time_ms += elapsed_ms; 5871 5872 start_sec = os::elapsedTime(); 5873 non_young = false; 5874 } 5875 } else { 5876 if (!cur->is_young()) { 5877 double end_sec = os::elapsedTime(); 5878 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5879 young_time_ms += elapsed_ms; 5880 5881 start_sec = os::elapsedTime(); 5882 non_young = true; 5883 } 5884 } 5885 5886 rs_lengths += cur->rem_set()->occupied_locked(); 5887 5888 HeapRegion* next = cur->next_in_collection_set(); 5889 assert(cur->in_collection_set(), "bad CS"); 5890 cur->set_next_in_collection_set(NULL); 5891 clear_in_cset(cur); 5892 5893 if (cur->is_young()) { 5894 int index = cur->young_index_in_cset(); 5895 assert(index != -1, "invariant"); 5896 assert((uint) index < policy->young_cset_region_length(), "invariant"); 5897 size_t words_survived = _surviving_young_words[index]; 5898 cur->record_surv_words_in_group(words_survived); 5899 5900 // At this point the we have 'popped' cur from the collection set 5901 // (linked via next_in_collection_set()) but it is still in the 5902 // young list (linked via next_young_region()). Clear the 5903 // _next_young_region field. 5904 cur->set_next_young_region(NULL); 5905 } else { 5906 int index = cur->young_index_in_cset(); 5907 assert(index == -1, "invariant"); 5908 } 5909 5910 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 5911 (!cur->is_young() && cur->young_index_in_cset() == -1), 5912 "invariant" ); 5913 5914 if (!cur->evacuation_failed()) { 5915 MemRegion used_mr = cur->used_region(); 5916 5917 // And the region is empty. 5918 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 5919 pre_used += cur->used(); 5920 free_region(cur, &local_free_list, false /* par */, true /* locked */); 5921 } else { 5922 cur->uninstall_surv_rate_group(); 5923 if (cur->is_young()) { 5924 cur->set_young_index_in_cset(-1); 5925 } 5926 cur->set_evacuation_failed(false); 5927 // The region is now considered to be old. 5928 cur->set_old(); 5929 _old_set.add(cur); 5930 evacuation_info.increment_collectionset_used_after(cur->used()); 5931 } 5932 cur = next; 5933 } 5934 5935 evacuation_info.set_regions_freed(local_free_list.length()); 5936 policy->record_max_rs_lengths(rs_lengths); 5937 policy->cset_regions_freed(); 5938 5939 double end_sec = os::elapsedTime(); 5940 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5941 5942 if (non_young) { 5943 non_young_time_ms += elapsed_ms; 5944 } else { 5945 young_time_ms += elapsed_ms; 5946 } 5947 5948 prepend_to_freelist(&local_free_list); 5949 decrement_summary_bytes(pre_used); 5950 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 5951 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 5952 } 5953 5954 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 5955 private: 5956 FreeRegionList* _free_region_list; 5957 HeapRegionSet* _proxy_set; 5958 HeapRegionSetCount _humongous_regions_removed; 5959 size_t _freed_bytes; 5960 public: 5961 5962 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 5963 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 5964 } 5965 5966 virtual bool doHeapRegion(HeapRegion* r) { 5967 if (!r->is_starts_humongous()) { 5968 return false; 5969 } 5970 5971 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 5972 5973 oop obj = (oop)r->bottom(); 5974 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 5975 5976 // The following checks whether the humongous object is live are sufficient. 5977 // The main additional check (in addition to having a reference from the roots 5978 // or the young gen) is whether the humongous object has a remembered set entry. 5979 // 5980 // A humongous object cannot be live if there is no remembered set for it 5981 // because: 5982 // - there can be no references from within humongous starts regions referencing 5983 // the object because we never allocate other objects into them. 5984 // (I.e. there are no intra-region references that may be missed by the 5985 // remembered set) 5986 // - as soon there is a remembered set entry to the humongous starts region 5987 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 5988 // until the end of a concurrent mark. 5989 // 5990 // It is not required to check whether the object has been found dead by marking 5991 // or not, in fact it would prevent reclamation within a concurrent cycle, as 5992 // all objects allocated during that time are considered live. 5993 // SATB marking is even more conservative than the remembered set. 5994 // So if at this point in the collection there is no remembered set entry, 5995 // nobody has a reference to it. 5996 // At the start of collection we flush all refinement logs, and remembered sets 5997 // are completely up-to-date wrt to references to the humongous object. 5998 // 5999 // Other implementation considerations: 6000 // - never consider object arrays at this time because they would pose 6001 // considerable effort for cleaning up the the remembered sets. This is 6002 // required because stale remembered sets might reference locations that 6003 // are currently allocated into. 6004 uint region_idx = r->hrm_index(); 6005 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 6006 !r->rem_set()->is_empty()) { 6007 6008 if (G1TraceEagerReclaimHumongousObjects) { 6009 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 reclaim candidate %d type array %d", 6010 region_idx, 6011 obj->size()*HeapWordSize, 6012 r->bottom(), 6013 r->region_num(), 6014 r->rem_set()->occupied(), 6015 r->rem_set()->strong_code_roots_list_length(), 6016 next_bitmap->isMarked(r->bottom()), 6017 g1h->is_humongous_reclaim_candidate(region_idx), 6018 obj->is_typeArray() 6019 ); 6020 } 6021 6022 return false; 6023 } 6024 6025 guarantee(obj->is_typeArray(), 6026 err_msg("Only eagerly reclaiming type arrays is supported, but the object " 6027 PTR_FORMAT " is not.", 6028 r->bottom())); 6029 6030 if (G1TraceEagerReclaimHumongousObjects) { 6031 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 reclaim candidate %d type array %d", 6032 region_idx, 6033 obj->size()*HeapWordSize, 6034 r->bottom(), 6035 r->region_num(), 6036 r->rem_set()->occupied(), 6037 r->rem_set()->strong_code_roots_list_length(), 6038 next_bitmap->isMarked(r->bottom()), 6039 g1h->is_humongous_reclaim_candidate(region_idx), 6040 obj->is_typeArray() 6041 ); 6042 } 6043 // Need to clear mark bit of the humongous object if already set. 6044 if (next_bitmap->isMarked(r->bottom())) { 6045 next_bitmap->clear(r->bottom()); 6046 } 6047 _freed_bytes += r->used(); 6048 r->set_containing_set(NULL); 6049 _humongous_regions_removed.increment(1u, r->capacity()); 6050 g1h->free_humongous_region(r, _free_region_list, false); 6051 6052 return false; 6053 } 6054 6055 HeapRegionSetCount& humongous_free_count() { 6056 return _humongous_regions_removed; 6057 } 6058 6059 size_t bytes_freed() const { 6060 return _freed_bytes; 6061 } 6062 6063 size_t humongous_reclaimed() const { 6064 return _humongous_regions_removed.length(); 6065 } 6066 }; 6067 6068 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 6069 assert_at_safepoint(true); 6070 6071 if (!G1EagerReclaimHumongousObjects || 6072 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) { 6073 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 6074 return; 6075 } 6076 6077 double start_time = os::elapsedTime(); 6078 6079 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 6080 6081 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 6082 heap_region_iterate(&cl); 6083 6084 HeapRegionSetCount empty_set; 6085 remove_from_old_sets(empty_set, cl.humongous_free_count()); 6086 6087 G1HRPrinter* hrp = hr_printer(); 6088 if (hrp->is_active()) { 6089 FreeRegionListIterator iter(&local_cleanup_list); 6090 while (iter.more_available()) { 6091 HeapRegion* hr = iter.get_next(); 6092 hrp->cleanup(hr); 6093 } 6094 } 6095 6096 prepend_to_freelist(&local_cleanup_list); 6097 decrement_summary_bytes(cl.bytes_freed()); 6098 6099 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 6100 cl.humongous_reclaimed()); 6101 } 6102 6103 // This routine is similar to the above but does not record 6104 // any policy statistics or update free lists; we are abandoning 6105 // the current incremental collection set in preparation of a 6106 // full collection. After the full GC we will start to build up 6107 // the incremental collection set again. 6108 // This is only called when we're doing a full collection 6109 // and is immediately followed by the tearing down of the young list. 6110 6111 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6112 HeapRegion* cur = cs_head; 6113 6114 while (cur != NULL) { 6115 HeapRegion* next = cur->next_in_collection_set(); 6116 assert(cur->in_collection_set(), "bad CS"); 6117 cur->set_next_in_collection_set(NULL); 6118 clear_in_cset(cur); 6119 cur->set_young_index_in_cset(-1); 6120 cur = next; 6121 } 6122 } 6123 6124 void G1CollectedHeap::set_free_regions_coming() { 6125 if (G1ConcRegionFreeingVerbose) { 6126 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6127 "setting free regions coming"); 6128 } 6129 6130 assert(!free_regions_coming(), "pre-condition"); 6131 _free_regions_coming = true; 6132 } 6133 6134 void G1CollectedHeap::reset_free_regions_coming() { 6135 assert(free_regions_coming(), "pre-condition"); 6136 6137 { 6138 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6139 _free_regions_coming = false; 6140 SecondaryFreeList_lock->notify_all(); 6141 } 6142 6143 if (G1ConcRegionFreeingVerbose) { 6144 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6145 "reset free regions coming"); 6146 } 6147 } 6148 6149 void G1CollectedHeap::wait_while_free_regions_coming() { 6150 // Most of the time we won't have to wait, so let's do a quick test 6151 // first before we take the lock. 6152 if (!free_regions_coming()) { 6153 return; 6154 } 6155 6156 if (G1ConcRegionFreeingVerbose) { 6157 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6158 "waiting for free regions"); 6159 } 6160 6161 { 6162 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6163 while (free_regions_coming()) { 6164 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6165 } 6166 } 6167 6168 if (G1ConcRegionFreeingVerbose) { 6169 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6170 "done waiting for free regions"); 6171 } 6172 } 6173 6174 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6175 _young_list->push_region(hr); 6176 } 6177 6178 class NoYoungRegionsClosure: public HeapRegionClosure { 6179 private: 6180 bool _success; 6181 public: 6182 NoYoungRegionsClosure() : _success(true) { } 6183 bool doHeapRegion(HeapRegion* r) { 6184 if (r->is_young()) { 6185 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6186 r->bottom(), r->end()); 6187 _success = false; 6188 } 6189 return false; 6190 } 6191 bool success() { return _success; } 6192 }; 6193 6194 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6195 bool ret = _young_list->check_list_empty(check_sample); 6196 6197 if (check_heap) { 6198 NoYoungRegionsClosure closure; 6199 heap_region_iterate(&closure); 6200 ret = ret && closure.success(); 6201 } 6202 6203 return ret; 6204 } 6205 6206 class TearDownRegionSetsClosure : public HeapRegionClosure { 6207 private: 6208 HeapRegionSet *_old_set; 6209 6210 public: 6211 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6212 6213 bool doHeapRegion(HeapRegion* r) { 6214 if (r->is_old()) { 6215 _old_set->remove(r); 6216 } else { 6217 // We ignore free regions, we'll empty the free list afterwards. 6218 // We ignore young regions, we'll empty the young list afterwards. 6219 // We ignore humongous regions, we're not tearing down the 6220 // humongous regions set. 6221 assert(r->is_free() || r->is_young() || r->is_humongous(), 6222 "it cannot be another type"); 6223 } 6224 return false; 6225 } 6226 6227 ~TearDownRegionSetsClosure() { 6228 assert(_old_set->is_empty(), "post-condition"); 6229 } 6230 }; 6231 6232 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6233 assert_at_safepoint(true /* should_be_vm_thread */); 6234 6235 if (!free_list_only) { 6236 TearDownRegionSetsClosure cl(&_old_set); 6237 heap_region_iterate(&cl); 6238 6239 // Note that emptying the _young_list is postponed and instead done as 6240 // the first step when rebuilding the regions sets again. The reason for 6241 // this is that during a full GC string deduplication needs to know if 6242 // a collected region was young or old when the full GC was initiated. 6243 } 6244 _hrm.remove_all_free_regions(); 6245 } 6246 6247 class RebuildRegionSetsClosure : public HeapRegionClosure { 6248 private: 6249 bool _free_list_only; 6250 HeapRegionSet* _old_set; 6251 HeapRegionManager* _hrm; 6252 size_t _total_used; 6253 6254 public: 6255 RebuildRegionSetsClosure(bool free_list_only, 6256 HeapRegionSet* old_set, HeapRegionManager* hrm) : 6257 _free_list_only(free_list_only), 6258 _old_set(old_set), _hrm(hrm), _total_used(0) { 6259 assert(_hrm->num_free_regions() == 0, "pre-condition"); 6260 if (!free_list_only) { 6261 assert(_old_set->is_empty(), "pre-condition"); 6262 } 6263 } 6264 6265 bool doHeapRegion(HeapRegion* r) { 6266 if (r->is_continues_humongous()) { 6267 return false; 6268 } 6269 6270 if (r->is_empty()) { 6271 // Add free regions to the free list 6272 r->set_free(); 6273 r->set_allocation_context(AllocationContext::system()); 6274 _hrm->insert_into_free_list(r); 6275 } else if (!_free_list_only) { 6276 assert(!r->is_young(), "we should not come across young regions"); 6277 6278 if (r->is_humongous()) { 6279 // We ignore humongous regions, we left the humongous set unchanged 6280 } else { 6281 // Objects that were compacted would have ended up on regions 6282 // that were previously old or free. 6283 assert(r->is_free() || r->is_old(), "invariant"); 6284 // We now consider them old, so register as such. 6285 r->set_old(); 6286 _old_set->add(r); 6287 } 6288 _total_used += r->used(); 6289 } 6290 6291 return false; 6292 } 6293 6294 size_t total_used() { 6295 return _total_used; 6296 } 6297 }; 6298 6299 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6300 assert_at_safepoint(true /* should_be_vm_thread */); 6301 6302 if (!free_list_only) { 6303 _young_list->empty_list(); 6304 } 6305 6306 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 6307 heap_region_iterate(&cl); 6308 6309 if (!free_list_only) { 6310 _allocator->set_used(cl.total_used()); 6311 } 6312 assert(_allocator->used_unlocked() == recalculate_used(), 6313 err_msg("inconsistent _allocator->used_unlocked(), " 6314 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6315 _allocator->used_unlocked(), recalculate_used())); 6316 } 6317 6318 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6319 _refine_cte_cl->set_concurrent(concurrent); 6320 } 6321 6322 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6323 HeapRegion* hr = heap_region_containing(p); 6324 return hr->is_in(p); 6325 } 6326 6327 // Methods for the mutator alloc region 6328 6329 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6330 bool force) { 6331 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6332 assert(!force || g1_policy()->can_expand_young_list(), 6333 "if force is true we should be able to expand the young list"); 6334 bool young_list_full = g1_policy()->is_young_list_full(); 6335 if (force || !young_list_full) { 6336 HeapRegion* new_alloc_region = new_region(word_size, 6337 false /* is_old */, 6338 false /* do_expand */); 6339 if (new_alloc_region != NULL) { 6340 set_region_short_lived_locked(new_alloc_region); 6341 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6342 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6343 return new_alloc_region; 6344 } 6345 } 6346 return NULL; 6347 } 6348 6349 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6350 size_t allocated_bytes) { 6351 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6352 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 6353 6354 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6355 _allocator->increase_used(allocated_bytes); 6356 _hr_printer.retire(alloc_region); 6357 // We update the eden sizes here, when the region is retired, 6358 // instead of when it's allocated, since this is the point that its 6359 // used space has been recored in _summary_bytes_used. 6360 g1mm()->update_eden_size(); 6361 } 6362 6363 void G1CollectedHeap::set_par_threads() { 6364 // Don't change the number of workers. Use the value previously set 6365 // in the workgroup. 6366 uint n_workers = workers()->active_workers(); 6367 assert(UseDynamicNumberOfGCThreads || 6368 n_workers == workers()->total_workers(), 6369 "Otherwise should be using the total number of workers"); 6370 if (n_workers == 0) { 6371 assert(false, "Should have been set in prior evacuation pause."); 6372 n_workers = ParallelGCThreads; 6373 workers()->set_active_workers(n_workers); 6374 } 6375 set_par_threads(n_workers); 6376 } 6377 6378 // Methods for the GC alloc regions 6379 6380 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6381 uint count, 6382 InCSetState dest) { 6383 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6384 6385 if (count < g1_policy()->max_regions(dest)) { 6386 const bool is_survivor = (dest.is_young()); 6387 HeapRegion* new_alloc_region = new_region(word_size, 6388 !is_survivor, 6389 true /* do_expand */); 6390 if (new_alloc_region != NULL) { 6391 // We really only need to do this for old regions given that we 6392 // should never scan survivors. But it doesn't hurt to do it 6393 // for survivors too. 6394 new_alloc_region->record_timestamp(); 6395 if (is_survivor) { 6396 new_alloc_region->set_survivor(); 6397 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6398 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6399 } else { 6400 new_alloc_region->set_old(); 6401 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6402 check_bitmaps("Old Region Allocation", new_alloc_region); 6403 } 6404 bool during_im = g1_policy()->during_initial_mark_pause(); 6405 new_alloc_region->note_start_of_copying(during_im); 6406 return new_alloc_region; 6407 } 6408 } 6409 return NULL; 6410 } 6411 6412 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6413 size_t allocated_bytes, 6414 InCSetState dest) { 6415 bool during_im = g1_policy()->during_initial_mark_pause(); 6416 alloc_region->note_end_of_copying(during_im); 6417 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6418 if (dest.is_young()) { 6419 young_list()->add_survivor_region(alloc_region); 6420 } else { 6421 _old_set.add(alloc_region); 6422 } 6423 _hr_printer.retire(alloc_region); 6424 } 6425 6426 // Heap region set verification 6427 6428 class VerifyRegionListsClosure : public HeapRegionClosure { 6429 private: 6430 HeapRegionSet* _old_set; 6431 HeapRegionSet* _humongous_set; 6432 HeapRegionManager* _hrm; 6433 6434 public: 6435 HeapRegionSetCount _old_count; 6436 HeapRegionSetCount _humongous_count; 6437 HeapRegionSetCount _free_count; 6438 6439 VerifyRegionListsClosure(HeapRegionSet* old_set, 6440 HeapRegionSet* humongous_set, 6441 HeapRegionManager* hrm) : 6442 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm), 6443 _old_count(), _humongous_count(), _free_count(){ } 6444 6445 bool doHeapRegion(HeapRegion* hr) { 6446 if (hr->is_continues_humongous()) { 6447 return false; 6448 } 6449 6450 if (hr->is_young()) { 6451 // TODO 6452 } else if (hr->is_starts_humongous()) { 6453 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index())); 6454 _humongous_count.increment(1u, hr->capacity()); 6455 } else if (hr->is_empty()) { 6456 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index())); 6457 _free_count.increment(1u, hr->capacity()); 6458 } else if (hr->is_old()) { 6459 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index())); 6460 _old_count.increment(1u, hr->capacity()); 6461 } else { 6462 ShouldNotReachHere(); 6463 } 6464 return false; 6465 } 6466 6467 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) { 6468 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 6469 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6470 old_set->total_capacity_bytes(), _old_count.capacity())); 6471 6472 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 6473 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6474 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 6475 6476 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())); 6477 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6478 free_list->total_capacity_bytes(), _free_count.capacity())); 6479 } 6480 }; 6481 6482 void G1CollectedHeap::verify_region_sets() { 6483 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6484 6485 // First, check the explicit lists. 6486 _hrm.verify(); 6487 { 6488 // Given that a concurrent operation might be adding regions to 6489 // the secondary free list we have to take the lock before 6490 // verifying it. 6491 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6492 _secondary_free_list.verify_list(); 6493 } 6494 6495 // If a concurrent region freeing operation is in progress it will 6496 // be difficult to correctly attributed any free regions we come 6497 // across to the correct free list given that they might belong to 6498 // one of several (free_list, secondary_free_list, any local lists, 6499 // etc.). So, if that's the case we will skip the rest of the 6500 // verification operation. Alternatively, waiting for the concurrent 6501 // operation to complete will have a non-trivial effect on the GC's 6502 // operation (no concurrent operation will last longer than the 6503 // interval between two calls to verification) and it might hide 6504 // any issues that we would like to catch during testing. 6505 if (free_regions_coming()) { 6506 return; 6507 } 6508 6509 // Make sure we append the secondary_free_list on the free_list so 6510 // that all free regions we will come across can be safely 6511 // attributed to the free_list. 6512 append_secondary_free_list_if_not_empty_with_lock(); 6513 6514 // Finally, make sure that the region accounting in the lists is 6515 // consistent with what we see in the heap. 6516 6517 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm); 6518 heap_region_iterate(&cl); 6519 cl.verify_counts(&_old_set, &_humongous_set, &_hrm); 6520 } 6521 6522 // Optimized nmethod scanning 6523 6524 class RegisterNMethodOopClosure: public OopClosure { 6525 G1CollectedHeap* _g1h; 6526 nmethod* _nm; 6527 6528 template <class T> void do_oop_work(T* p) { 6529 T heap_oop = oopDesc::load_heap_oop(p); 6530 if (!oopDesc::is_null(heap_oop)) { 6531 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6532 HeapRegion* hr = _g1h->heap_region_containing(obj); 6533 assert(!hr->is_continues_humongous(), 6534 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6535 " starting at "HR_FORMAT, 6536 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6537 6538 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 6539 hr->add_strong_code_root_locked(_nm); 6540 } 6541 } 6542 6543 public: 6544 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6545 _g1h(g1h), _nm(nm) {} 6546 6547 void do_oop(oop* p) { do_oop_work(p); } 6548 void do_oop(narrowOop* p) { do_oop_work(p); } 6549 }; 6550 6551 class UnregisterNMethodOopClosure: public OopClosure { 6552 G1CollectedHeap* _g1h; 6553 nmethod* _nm; 6554 6555 template <class T> void do_oop_work(T* p) { 6556 T heap_oop = oopDesc::load_heap_oop(p); 6557 if (!oopDesc::is_null(heap_oop)) { 6558 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6559 HeapRegion* hr = _g1h->heap_region_containing(obj); 6560 assert(!hr->is_continues_humongous(), 6561 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6562 " starting at "HR_FORMAT, 6563 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6564 6565 hr->remove_strong_code_root(_nm); 6566 } 6567 } 6568 6569 public: 6570 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6571 _g1h(g1h), _nm(nm) {} 6572 6573 void do_oop(oop* p) { do_oop_work(p); } 6574 void do_oop(narrowOop* p) { do_oop_work(p); } 6575 }; 6576 6577 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6578 CollectedHeap::register_nmethod(nm); 6579 6580 guarantee(nm != NULL, "sanity"); 6581 RegisterNMethodOopClosure reg_cl(this, nm); 6582 nm->oops_do(®_cl); 6583 } 6584 6585 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6586 CollectedHeap::unregister_nmethod(nm); 6587 6588 guarantee(nm != NULL, "sanity"); 6589 UnregisterNMethodOopClosure reg_cl(this, nm); 6590 nm->oops_do(®_cl, true); 6591 } 6592 6593 void G1CollectedHeap::purge_code_root_memory() { 6594 double purge_start = os::elapsedTime(); 6595 G1CodeRootSet::purge(); 6596 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6597 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6598 } 6599 6600 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6601 G1CollectedHeap* _g1h; 6602 6603 public: 6604 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6605 _g1h(g1h) {} 6606 6607 void do_code_blob(CodeBlob* cb) { 6608 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6609 if (nm == NULL) { 6610 return; 6611 } 6612 6613 if (ScavengeRootsInCode) { 6614 _g1h->register_nmethod(nm); 6615 } 6616 } 6617 }; 6618 6619 void G1CollectedHeap::rebuild_strong_code_roots() { 6620 RebuildStrongCodeRootClosure blob_cl(this); 6621 CodeCache::blobs_do(&blob_cl); 6622 }