1 /* 2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/metadataOnStackMark.hpp" 27 #include "classfile/stringTable.hpp" 28 #include "code/codeCache.hpp" 29 #include "code/icBuffer.hpp" 30 #include "gc/g1/bufferingOopClosure.hpp" 31 #include "gc/g1/concurrentG1Refine.hpp" 32 #include "gc/g1/concurrentG1RefineThread.hpp" 33 #include "gc/g1/concurrentMarkThread.inline.hpp" 34 #include "gc/g1/g1AllocRegion.inline.hpp" 35 #include "gc/g1/g1CollectedHeap.inline.hpp" 36 #include "gc/g1/g1CollectorPolicy.hpp" 37 #include "gc/g1/g1ErgoVerbose.hpp" 38 #include "gc/g1/g1EvacFailure.hpp" 39 #include "gc/g1/g1GCPhaseTimes.hpp" 40 #include "gc/g1/g1Log.hpp" 41 #include "gc/g1/g1MarkSweep.hpp" 42 #include "gc/g1/g1OopClosures.inline.hpp" 43 #include "gc/g1/g1ParScanThreadState.inline.hpp" 44 #include "gc/g1/g1RegionToSpaceMapper.hpp" 45 #include "gc/g1/g1RemSet.inline.hpp" 46 #include "gc/g1/g1RootProcessor.hpp" 47 #include "gc/g1/g1StringDedup.hpp" 48 #include "gc/g1/g1YCTypes.hpp" 49 #include "gc/g1/heapRegion.inline.hpp" 50 #include "gc/g1/heapRegionRemSet.hpp" 51 #include "gc/g1/heapRegionSet.inline.hpp" 52 #include "gc/g1/vm_operations_g1.hpp" 53 #include "gc/shared/gcHeapSummary.hpp" 54 #include "gc/shared/gcLocker.inline.hpp" 55 #include "gc/shared/gcTimer.hpp" 56 #include "gc/shared/gcTrace.hpp" 57 #include "gc/shared/gcTraceTime.hpp" 58 #include "gc/shared/generationSpec.hpp" 59 #include "gc/shared/isGCActiveMark.hpp" 60 #include "gc/shared/referenceProcessor.hpp" 61 #include "gc/shared/taskqueue.inline.hpp" 62 #include "memory/allocation.hpp" 63 #include "memory/iterator.hpp" 64 #include "oops/oop.inline.hpp" 65 #include "runtime/atomic.inline.hpp" 66 #include "runtime/orderAccess.inline.hpp" 67 #include "runtime/vmThread.hpp" 68 #include "utilities/globalDefinitions.hpp" 69 #include "utilities/stack.inline.hpp" 70 71 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 72 73 // turn it on so that the contents of the young list (scan-only / 74 // to-be-collected) are printed at "strategic" points before / during 75 // / after the collection --- this is useful for debugging 76 #define YOUNG_LIST_VERBOSE 0 77 // CURRENT STATUS 78 // This file is under construction. Search for "FIXME". 79 80 // INVARIANTS/NOTES 81 // 82 // All allocation activity covered by the G1CollectedHeap interface is 83 // serialized by acquiring the HeapLock. This happens in mem_allocate 84 // and allocate_new_tlab, which are the "entry" points to the 85 // allocation code from the rest of the JVM. (Note that this does not 86 // apply to TLAB allocation, which is not part of this interface: it 87 // is done by clients of this interface.) 88 89 // Local to this file. 90 91 class RefineCardTableEntryClosure: public CardTableEntryClosure { 92 bool _concurrent; 93 public: 94 RefineCardTableEntryClosure() : _concurrent(true) { } 95 96 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 97 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 98 // This path is executed by the concurrent refine or mutator threads, 99 // concurrently, and so we do not care if card_ptr contains references 100 // that point into the collection set. 101 assert(!oops_into_cset, "should be"); 102 103 if (_concurrent && SuspendibleThreadSet::should_yield()) { 104 // Caller will actually yield. 105 return false; 106 } 107 // Otherwise, we finished successfully; return true. 108 return true; 109 } 110 111 void set_concurrent(bool b) { _concurrent = b; } 112 }; 113 114 115 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 116 private: 117 size_t _num_processed; 118 119 public: 120 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { } 121 122 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 123 *card_ptr = CardTableModRefBS::dirty_card_val(); 124 _num_processed++; 125 return true; 126 } 127 128 size_t num_processed() const { return _num_processed; } 129 }; 130 131 YoungList::YoungList(G1CollectedHeap* g1h) : 132 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 133 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 134 guarantee(check_list_empty(false), "just making sure..."); 135 } 136 137 void YoungList::push_region(HeapRegion *hr) { 138 assert(!hr->is_young(), "should not already be young"); 139 assert(hr->get_next_young_region() == NULL, "cause it should!"); 140 141 hr->set_next_young_region(_head); 142 _head = hr; 143 144 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 145 ++_length; 146 } 147 148 void YoungList::add_survivor_region(HeapRegion* hr) { 149 assert(hr->is_survivor(), "should be flagged as survivor region"); 150 assert(hr->get_next_young_region() == NULL, "cause it should!"); 151 152 hr->set_next_young_region(_survivor_head); 153 if (_survivor_head == NULL) { 154 _survivor_tail = hr; 155 } 156 _survivor_head = hr; 157 ++_survivor_length; 158 } 159 160 void YoungList::empty_list(HeapRegion* list) { 161 while (list != NULL) { 162 HeapRegion* next = list->get_next_young_region(); 163 list->set_next_young_region(NULL); 164 list->uninstall_surv_rate_group(); 165 // This is called before a Full GC and all the non-empty / 166 // non-humongous regions at the end of the Full GC will end up as 167 // old anyway. 168 list->set_old(); 169 list = next; 170 } 171 } 172 173 void YoungList::empty_list() { 174 assert(check_list_well_formed(), "young list should be well formed"); 175 176 empty_list(_head); 177 _head = NULL; 178 _length = 0; 179 180 empty_list(_survivor_head); 181 _survivor_head = NULL; 182 _survivor_tail = NULL; 183 _survivor_length = 0; 184 185 _last_sampled_rs_lengths = 0; 186 187 assert(check_list_empty(false), "just making sure..."); 188 } 189 190 bool YoungList::check_list_well_formed() { 191 bool ret = true; 192 193 uint length = 0; 194 HeapRegion* curr = _head; 195 HeapRegion* last = NULL; 196 while (curr != NULL) { 197 if (!curr->is_young()) { 198 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " 199 "incorrectly tagged (y: %d, surv: %d)", 200 p2i(curr->bottom()), p2i(curr->end()), 201 curr->is_young(), curr->is_survivor()); 202 ret = false; 203 } 204 ++length; 205 last = curr; 206 curr = curr->get_next_young_region(); 207 } 208 ret = ret && (length == _length); 209 210 if (!ret) { 211 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 212 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 213 length, _length); 214 } 215 216 return ret; 217 } 218 219 bool YoungList::check_list_empty(bool check_sample) { 220 bool ret = true; 221 222 if (_length != 0) { 223 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 224 _length); 225 ret = false; 226 } 227 if (check_sample && _last_sampled_rs_lengths != 0) { 228 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 229 ret = false; 230 } 231 if (_head != NULL) { 232 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 233 ret = false; 234 } 235 if (!ret) { 236 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 237 } 238 239 return ret; 240 } 241 242 void 243 YoungList::rs_length_sampling_init() { 244 _sampled_rs_lengths = 0; 245 _curr = _head; 246 } 247 248 bool 249 YoungList::rs_length_sampling_more() { 250 return _curr != NULL; 251 } 252 253 void 254 YoungList::rs_length_sampling_next() { 255 assert( _curr != NULL, "invariant" ); 256 size_t rs_length = _curr->rem_set()->occupied(); 257 258 _sampled_rs_lengths += rs_length; 259 260 // The current region may not yet have been added to the 261 // incremental collection set (it gets added when it is 262 // retired as the current allocation region). 263 if (_curr->in_collection_set()) { 264 // Update the collection set policy information for this region 265 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 266 } 267 268 _curr = _curr->get_next_young_region(); 269 if (_curr == NULL) { 270 _last_sampled_rs_lengths = _sampled_rs_lengths; 271 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 272 } 273 } 274 275 void 276 YoungList::reset_auxilary_lists() { 277 guarantee( is_empty(), "young list should be empty" ); 278 assert(check_list_well_formed(), "young list should be well formed"); 279 280 // Add survivor regions to SurvRateGroup. 281 _g1h->g1_policy()->note_start_adding_survivor_regions(); 282 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 283 284 int young_index_in_cset = 0; 285 for (HeapRegion* curr = _survivor_head; 286 curr != NULL; 287 curr = curr->get_next_young_region()) { 288 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 289 290 // The region is a non-empty survivor so let's add it to 291 // the incremental collection set for the next evacuation 292 // pause. 293 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 294 young_index_in_cset += 1; 295 } 296 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 297 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 298 299 _head = _survivor_head; 300 _length = _survivor_length; 301 if (_survivor_head != NULL) { 302 assert(_survivor_tail != NULL, "cause it shouldn't be"); 303 assert(_survivor_length > 0, "invariant"); 304 _survivor_tail->set_next_young_region(NULL); 305 } 306 307 // Don't clear the survivor list handles until the start of 308 // the next evacuation pause - we need it in order to re-tag 309 // the survivor regions from this evacuation pause as 'young' 310 // at the start of the next. 311 312 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 313 314 assert(check_list_well_formed(), "young list should be well formed"); 315 } 316 317 void YoungList::print() { 318 HeapRegion* lists[] = {_head, _survivor_head}; 319 const char* names[] = {"YOUNG", "SURVIVOR"}; 320 321 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) { 322 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 323 HeapRegion *curr = lists[list]; 324 if (curr == NULL) 325 gclog_or_tty->print_cr(" empty"); 326 while (curr != NULL) { 327 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d", 328 HR_FORMAT_PARAMS(curr), 329 p2i(curr->prev_top_at_mark_start()), 330 p2i(curr->next_top_at_mark_start()), 331 curr->age_in_surv_rate_group_cond()); 332 curr = curr->get_next_young_region(); 333 } 334 } 335 336 gclog_or_tty->cr(); 337 } 338 339 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 340 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 341 } 342 343 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 344 // The from card cache is not the memory that is actually committed. So we cannot 345 // take advantage of the zero_filled parameter. 346 reset_from_card_cache(start_idx, num_regions); 347 } 348 349 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 350 { 351 // Claim the right to put the region on the dirty cards region list 352 // by installing a self pointer. 353 HeapRegion* next = hr->get_next_dirty_cards_region(); 354 if (next == NULL) { 355 HeapRegion* res = (HeapRegion*) 356 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 357 NULL); 358 if (res == NULL) { 359 HeapRegion* head; 360 do { 361 // Put the region to the dirty cards region list. 362 head = _dirty_cards_region_list; 363 next = (HeapRegion*) 364 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 365 if (next == head) { 366 assert(hr->get_next_dirty_cards_region() == hr, 367 "hr->get_next_dirty_cards_region() != hr"); 368 if (next == NULL) { 369 // The last region in the list points to itself. 370 hr->set_next_dirty_cards_region(hr); 371 } else { 372 hr->set_next_dirty_cards_region(next); 373 } 374 } 375 } while (next != head); 376 } 377 } 378 } 379 380 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 381 { 382 HeapRegion* head; 383 HeapRegion* hr; 384 do { 385 head = _dirty_cards_region_list; 386 if (head == NULL) { 387 return NULL; 388 } 389 HeapRegion* new_head = head->get_next_dirty_cards_region(); 390 if (head == new_head) { 391 // The last region. 392 new_head = NULL; 393 } 394 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 395 head); 396 } while (hr != head); 397 assert(hr != NULL, "invariant"); 398 hr->set_next_dirty_cards_region(NULL); 399 return hr; 400 } 401 402 // Returns true if the reference points to an object that 403 // can move in an incremental collection. 404 bool G1CollectedHeap::is_scavengable(const void* p) { 405 HeapRegion* hr = heap_region_containing(p); 406 return !hr->is_humongous(); 407 } 408 409 // Private methods. 410 411 HeapRegion* 412 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 413 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 414 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 415 if (!_secondary_free_list.is_empty()) { 416 if (G1ConcRegionFreeingVerbose) { 417 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 418 "secondary_free_list has %u entries", 419 _secondary_free_list.length()); 420 } 421 // It looks as if there are free regions available on the 422 // secondary_free_list. Let's move them to the free_list and try 423 // again to allocate from it. 424 append_secondary_free_list(); 425 426 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 427 "empty we should have moved at least one entry to the free_list"); 428 HeapRegion* res = _hrm.allocate_free_region(is_old); 429 if (G1ConcRegionFreeingVerbose) { 430 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 431 "allocated "HR_FORMAT" from secondary_free_list", 432 HR_FORMAT_PARAMS(res)); 433 } 434 return res; 435 } 436 437 // Wait here until we get notified either when (a) there are no 438 // more free regions coming or (b) some regions have been moved on 439 // the secondary_free_list. 440 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 441 } 442 443 if (G1ConcRegionFreeingVerbose) { 444 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 445 "could not allocate from secondary_free_list"); 446 } 447 return NULL; 448 } 449 450 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 451 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 452 "the only time we use this to allocate a humongous region is " 453 "when we are allocating a single humongous region"); 454 455 HeapRegion* res; 456 if (G1StressConcRegionFreeing) { 457 if (!_secondary_free_list.is_empty()) { 458 if (G1ConcRegionFreeingVerbose) { 459 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 460 "forced to look at the secondary_free_list"); 461 } 462 res = new_region_try_secondary_free_list(is_old); 463 if (res != NULL) { 464 return res; 465 } 466 } 467 } 468 469 res = _hrm.allocate_free_region(is_old); 470 471 if (res == NULL) { 472 if (G1ConcRegionFreeingVerbose) { 473 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 474 "res == NULL, trying the secondary_free_list"); 475 } 476 res = new_region_try_secondary_free_list(is_old); 477 } 478 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 479 // Currently, only attempts to allocate GC alloc regions set 480 // do_expand to true. So, we should only reach here during a 481 // safepoint. If this assumption changes we might have to 482 // reconsider the use of _expand_heap_after_alloc_failure. 483 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 484 485 ergo_verbose1(ErgoHeapSizing, 486 "attempt heap expansion", 487 ergo_format_reason("region allocation request failed") 488 ergo_format_byte("allocation request"), 489 word_size * HeapWordSize); 490 if (expand(word_size * HeapWordSize)) { 491 // Given that expand() succeeded in expanding the heap, and we 492 // always expand the heap by an amount aligned to the heap 493 // region size, the free list should in theory not be empty. 494 // In either case allocate_free_region() will check for NULL. 495 res = _hrm.allocate_free_region(is_old); 496 } else { 497 _expand_heap_after_alloc_failure = false; 498 } 499 } 500 return res; 501 } 502 503 HeapWord* 504 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 505 uint num_regions, 506 size_t word_size, 507 AllocationContext_t context) { 508 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 509 assert(is_humongous(word_size), "word_size should be humongous"); 510 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 511 512 // Index of last region in the series + 1. 513 uint last = first + num_regions; 514 515 // We need to initialize the region(s) we just discovered. This is 516 // a bit tricky given that it can happen concurrently with 517 // refinement threads refining cards on these regions and 518 // potentially wanting to refine the BOT as they are scanning 519 // those cards (this can happen shortly after a cleanup; see CR 520 // 6991377). So we have to set up the region(s) carefully and in 521 // a specific order. 522 523 // The word size sum of all the regions we will allocate. 524 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 525 assert(word_size <= word_size_sum, "sanity"); 526 527 // This will be the "starts humongous" region. 528 HeapRegion* first_hr = region_at(first); 529 // The header of the new object will be placed at the bottom of 530 // the first region. 531 HeapWord* new_obj = first_hr->bottom(); 532 // This will be the new end of the first region in the series that 533 // should also match the end of the last region in the series. 534 HeapWord* new_end = new_obj + word_size_sum; 535 // This will be the new top of the first region that will reflect 536 // this allocation. 537 HeapWord* new_top = new_obj + word_size; 538 539 // First, we need to zero the header of the space that we will be 540 // allocating. When we update top further down, some refinement 541 // threads might try to scan the region. By zeroing the header we 542 // ensure that any thread that will try to scan the region will 543 // come across the zero klass word and bail out. 544 // 545 // NOTE: It would not have been correct to have used 546 // CollectedHeap::fill_with_object() and make the space look like 547 // an int array. The thread that is doing the allocation will 548 // later update the object header to a potentially different array 549 // type and, for a very short period of time, the klass and length 550 // fields will be inconsistent. This could cause a refinement 551 // thread to calculate the object size incorrectly. 552 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 553 554 // We will set up the first region as "starts humongous". This 555 // will also update the BOT covering all the regions to reflect 556 // that there is a single object that starts at the bottom of the 557 // first region. 558 first_hr->set_starts_humongous(new_top, new_end); 559 first_hr->set_allocation_context(context); 560 // Then, if there are any, we will set up the "continues 561 // humongous" regions. 562 HeapRegion* hr = NULL; 563 for (uint i = first + 1; i < last; ++i) { 564 hr = region_at(i); 565 hr->set_continues_humongous(first_hr); 566 hr->set_allocation_context(context); 567 } 568 // If we have "continues humongous" regions (hr != NULL), then the 569 // end of the last one should match new_end. 570 assert(hr == NULL || hr->end() == new_end, "sanity"); 571 572 // Up to this point no concurrent thread would have been able to 573 // do any scanning on any region in this series. All the top 574 // fields still point to bottom, so the intersection between 575 // [bottom,top] and [card_start,card_end] will be empty. Before we 576 // update the top fields, we'll do a storestore to make sure that 577 // no thread sees the update to top before the zeroing of the 578 // object header and the BOT initialization. 579 OrderAccess::storestore(); 580 581 // Now that the BOT and the object header have been initialized, 582 // we can update top of the "starts humongous" region. 583 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 584 "new_top should be in this region"); 585 first_hr->set_top(new_top); 586 if (_hr_printer.is_active()) { 587 HeapWord* bottom = first_hr->bottom(); 588 HeapWord* end = first_hr->orig_end(); 589 if ((first + 1) == last) { 590 // the series has a single humongous region 591 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 592 } else { 593 // the series has more than one humongous regions 594 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 595 } 596 } 597 598 // Now, we will update the top fields of the "continues humongous" 599 // regions. The reason we need to do this is that, otherwise, 600 // these regions would look empty and this will confuse parts of 601 // G1. For example, the code that looks for a consecutive number 602 // of empty regions will consider them empty and try to 603 // re-allocate them. We can extend is_empty() to also include 604 // !is_continues_humongous(), but it is easier to just update the top 605 // fields here. The way we set top for all regions (i.e., top == 606 // end for all regions but the last one, top == new_top for the 607 // last one) is actually used when we will free up the humongous 608 // region in free_humongous_region(). 609 hr = NULL; 610 for (uint i = first + 1; i < last; ++i) { 611 hr = region_at(i); 612 if ((i + 1) == last) { 613 // last continues humongous region 614 assert(hr->bottom() < new_top && new_top <= hr->end(), 615 "new_top should fall on this region"); 616 hr->set_top(new_top); 617 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 618 } else { 619 // not last one 620 assert(new_top > hr->end(), "new_top should be above this region"); 621 hr->set_top(hr->end()); 622 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 623 } 624 } 625 // If we have continues humongous regions (hr != NULL), then the 626 // end of the last one should match new_end and its top should 627 // match new_top. 628 assert(hr == NULL || 629 (hr->end() == new_end && hr->top() == new_top), "sanity"); 630 check_bitmaps("Humongous Region Allocation", first_hr); 631 632 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 633 _allocator->increase_used(first_hr->used()); 634 _humongous_set.add(first_hr); 635 636 return new_obj; 637 } 638 639 // If could fit into free regions w/o expansion, try. 640 // Otherwise, if can expand, do so. 641 // Otherwise, if using ex regions might help, try with ex given back. 642 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 643 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 644 645 verify_region_sets_optional(); 646 647 uint first = G1_NO_HRM_INDEX; 648 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords); 649 650 if (obj_regions == 1) { 651 // Only one region to allocate, try to use a fast path by directly allocating 652 // from the free lists. Do not try to expand here, we will potentially do that 653 // later. 654 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 655 if (hr != NULL) { 656 first = hr->hrm_index(); 657 } 658 } else { 659 // We can't allocate humongous regions spanning more than one region while 660 // cleanupComplete() is running, since some of the regions we find to be 661 // empty might not yet be added to the free list. It is not straightforward 662 // to know in which list they are on so that we can remove them. We only 663 // need to do this if we need to allocate more than one region to satisfy the 664 // current humongous allocation request. If we are only allocating one region 665 // we use the one-region region allocation code (see above), that already 666 // potentially waits for regions from the secondary free list. 667 wait_while_free_regions_coming(); 668 append_secondary_free_list_if_not_empty_with_lock(); 669 670 // Policy: Try only empty regions (i.e. already committed first). Maybe we 671 // are lucky enough to find some. 672 first = _hrm.find_contiguous_only_empty(obj_regions); 673 if (first != G1_NO_HRM_INDEX) { 674 _hrm.allocate_free_regions_starting_at(first, obj_regions); 675 } 676 } 677 678 if (first == G1_NO_HRM_INDEX) { 679 // Policy: We could not find enough regions for the humongous object in the 680 // free list. Look through the heap to find a mix of free and uncommitted regions. 681 // If so, try expansion. 682 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 683 if (first != G1_NO_HRM_INDEX) { 684 // We found something. Make sure these regions are committed, i.e. expand 685 // the heap. Alternatively we could do a defragmentation GC. 686 ergo_verbose1(ErgoHeapSizing, 687 "attempt heap expansion", 688 ergo_format_reason("humongous allocation request failed") 689 ergo_format_byte("allocation request"), 690 word_size * HeapWordSize); 691 692 _hrm.expand_at(first, obj_regions); 693 g1_policy()->record_new_heap_size(num_regions()); 694 695 #ifdef ASSERT 696 for (uint i = first; i < first + obj_regions; ++i) { 697 HeapRegion* hr = region_at(i); 698 assert(hr->is_free(), "sanity"); 699 assert(hr->is_empty(), "sanity"); 700 assert(is_on_master_free_list(hr), "sanity"); 701 } 702 #endif 703 _hrm.allocate_free_regions_starting_at(first, obj_regions); 704 } else { 705 // Policy: Potentially trigger a defragmentation GC. 706 } 707 } 708 709 HeapWord* result = NULL; 710 if (first != G1_NO_HRM_INDEX) { 711 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 712 word_size, context); 713 assert(result != NULL, "it should always return a valid result"); 714 715 // A successful humongous object allocation changes the used space 716 // information of the old generation so we need to recalculate the 717 // sizes and update the jstat counters here. 718 g1mm()->update_sizes(); 719 } 720 721 verify_region_sets_optional(); 722 723 return result; 724 } 725 726 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 727 assert_heap_not_locked_and_not_at_safepoint(); 728 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 729 730 uint dummy_gc_count_before; 731 uint dummy_gclocker_retry_count = 0; 732 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 733 } 734 735 HeapWord* 736 G1CollectedHeap::mem_allocate(size_t word_size, 737 bool* gc_overhead_limit_was_exceeded) { 738 assert_heap_not_locked_and_not_at_safepoint(); 739 740 // Loop until the allocation is satisfied, or unsatisfied after GC. 741 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 742 uint gc_count_before; 743 744 HeapWord* result = NULL; 745 if (!is_humongous(word_size)) { 746 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 747 } else { 748 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 749 } 750 if (result != NULL) { 751 return result; 752 } 753 754 // Create the garbage collection operation... 755 VM_G1CollectForAllocation op(gc_count_before, word_size); 756 op.set_allocation_context(AllocationContext::current()); 757 758 // ...and get the VM thread to execute it. 759 VMThread::execute(&op); 760 761 if (op.prologue_succeeded() && op.pause_succeeded()) { 762 // If the operation was successful we'll return the result even 763 // if it is NULL. If the allocation attempt failed immediately 764 // after a Full GC, it's unlikely we'll be able to allocate now. 765 HeapWord* result = op.result(); 766 if (result != NULL && !is_humongous(word_size)) { 767 // Allocations that take place on VM operations do not do any 768 // card dirtying and we have to do it here. We only have to do 769 // this for non-humongous allocations, though. 770 dirty_young_block(result, word_size); 771 } 772 return result; 773 } else { 774 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 775 return NULL; 776 } 777 assert(op.result() == NULL, 778 "the result should be NULL if the VM op did not succeed"); 779 } 780 781 // Give a warning if we seem to be looping forever. 782 if ((QueuedAllocationWarningCount > 0) && 783 (try_count % QueuedAllocationWarningCount == 0)) { 784 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 785 } 786 } 787 788 ShouldNotReachHere(); 789 return NULL; 790 } 791 792 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 793 AllocationContext_t context, 794 uint* gc_count_before_ret, 795 uint* gclocker_retry_count_ret) { 796 // Make sure you read the note in attempt_allocation_humongous(). 797 798 assert_heap_not_locked_and_not_at_safepoint(); 799 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 800 "be called for humongous allocation requests"); 801 802 // We should only get here after the first-level allocation attempt 803 // (attempt_allocation()) failed to allocate. 804 805 // We will loop until a) we manage to successfully perform the 806 // allocation or b) we successfully schedule a collection which 807 // fails to perform the allocation. b) is the only case when we'll 808 // return NULL. 809 HeapWord* result = NULL; 810 for (int try_count = 1; /* we'll return */; try_count += 1) { 811 bool should_try_gc; 812 uint gc_count_before; 813 814 { 815 MutexLockerEx x(Heap_lock); 816 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, 817 false /* bot_updates */); 818 if (result != NULL) { 819 return result; 820 } 821 822 // If we reach here, attempt_allocation_locked() above failed to 823 // allocate a new region. So the mutator alloc region should be NULL. 824 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here"); 825 826 if (GC_locker::is_active_and_needs_gc()) { 827 if (g1_policy()->can_expand_young_list()) { 828 // No need for an ergo verbose message here, 829 // can_expand_young_list() does this when it returns true. 830 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size, 831 false /* bot_updates */); 832 if (result != NULL) { 833 return result; 834 } 835 } 836 should_try_gc = false; 837 } else { 838 // The GCLocker may not be active but the GCLocker initiated 839 // GC may not yet have been performed (GCLocker::needs_gc() 840 // returns true). In this case we do not try this GC and 841 // wait until the GCLocker initiated GC is performed, and 842 // then retry the allocation. 843 if (GC_locker::needs_gc()) { 844 should_try_gc = false; 845 } else { 846 // Read the GC count while still holding the Heap_lock. 847 gc_count_before = total_collections(); 848 should_try_gc = true; 849 } 850 } 851 } 852 853 if (should_try_gc) { 854 bool succeeded; 855 result = do_collection_pause(word_size, gc_count_before, &succeeded, 856 GCCause::_g1_inc_collection_pause); 857 if (result != NULL) { 858 assert(succeeded, "only way to get back a non-NULL result"); 859 return result; 860 } 861 862 if (succeeded) { 863 // If we get here we successfully scheduled a collection which 864 // failed to allocate. No point in trying to allocate 865 // further. We'll just return NULL. 866 MutexLockerEx x(Heap_lock); 867 *gc_count_before_ret = total_collections(); 868 return NULL; 869 } 870 } else { 871 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 872 MutexLockerEx x(Heap_lock); 873 *gc_count_before_ret = total_collections(); 874 return NULL; 875 } 876 // The GCLocker is either active or the GCLocker initiated 877 // GC has not yet been performed. Stall until it is and 878 // then retry the allocation. 879 GC_locker::stall_until_clear(); 880 (*gclocker_retry_count_ret) += 1; 881 } 882 883 // We can reach here if we were unsuccessful in scheduling a 884 // collection (because another thread beat us to it) or if we were 885 // stalled due to the GC locker. In either can we should retry the 886 // allocation attempt in case another thread successfully 887 // performed a collection and reclaimed enough space. We do the 888 // first attempt (without holding the Heap_lock) here and the 889 // follow-on attempt will be at the start of the next loop 890 // iteration (after taking the Heap_lock). 891 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size, 892 false /* bot_updates */); 893 if (result != NULL) { 894 return result; 895 } 896 897 // Give a warning if we seem to be looping forever. 898 if ((QueuedAllocationWarningCount > 0) && 899 (try_count % QueuedAllocationWarningCount == 0)) { 900 warning("G1CollectedHeap::attempt_allocation_slow() " 901 "retries %d times", try_count); 902 } 903 } 904 905 ShouldNotReachHere(); 906 return NULL; 907 } 908 909 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 910 uint* gc_count_before_ret, 911 uint* gclocker_retry_count_ret) { 912 // The structure of this method has a lot of similarities to 913 // attempt_allocation_slow(). The reason these two were not merged 914 // into a single one is that such a method would require several "if 915 // allocation is not humongous do this, otherwise do that" 916 // conditional paths which would obscure its flow. In fact, an early 917 // version of this code did use a unified method which was harder to 918 // follow and, as a result, it had subtle bugs that were hard to 919 // track down. So keeping these two methods separate allows each to 920 // be more readable. It will be good to keep these two in sync as 921 // much as possible. 922 923 assert_heap_not_locked_and_not_at_safepoint(); 924 assert(is_humongous(word_size), "attempt_allocation_humongous() " 925 "should only be called for humongous allocations"); 926 927 // Humongous objects can exhaust the heap quickly, so we should check if we 928 // need to start a marking cycle at each humongous object allocation. We do 929 // the check before we do the actual allocation. The reason for doing it 930 // before the allocation is that we avoid having to keep track of the newly 931 // allocated memory while we do a GC. 932 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 933 word_size)) { 934 collect(GCCause::_g1_humongous_allocation); 935 } 936 937 // We will loop until a) we manage to successfully perform the 938 // allocation or b) we successfully schedule a collection which 939 // fails to perform the allocation. b) is the only case when we'll 940 // return NULL. 941 HeapWord* result = NULL; 942 for (int try_count = 1; /* we'll return */; try_count += 1) { 943 bool should_try_gc; 944 uint gc_count_before; 945 946 { 947 MutexLockerEx x(Heap_lock); 948 949 // Given that humongous objects are not allocated in young 950 // regions, we'll first try to do the allocation without doing a 951 // collection hoping that there's enough space in the heap. 952 result = humongous_obj_allocate(word_size, AllocationContext::current()); 953 if (result != NULL) { 954 return result; 955 } 956 957 if (GC_locker::is_active_and_needs_gc()) { 958 should_try_gc = false; 959 } else { 960 // The GCLocker may not be active but the GCLocker initiated 961 // GC may not yet have been performed (GCLocker::needs_gc() 962 // returns true). In this case we do not try this GC and 963 // wait until the GCLocker initiated GC is performed, and 964 // then retry the allocation. 965 if (GC_locker::needs_gc()) { 966 should_try_gc = false; 967 } else { 968 // Read the GC count while still holding the Heap_lock. 969 gc_count_before = total_collections(); 970 should_try_gc = true; 971 } 972 } 973 } 974 975 if (should_try_gc) { 976 // If we failed to allocate the humongous object, we should try to 977 // do a collection pause (if we're allowed) in case it reclaims 978 // enough space for the allocation to succeed after the pause. 979 980 bool succeeded; 981 result = do_collection_pause(word_size, gc_count_before, &succeeded, 982 GCCause::_g1_humongous_allocation); 983 if (result != NULL) { 984 assert(succeeded, "only way to get back a non-NULL result"); 985 return result; 986 } 987 988 if (succeeded) { 989 // If we get here we successfully scheduled a collection which 990 // failed to allocate. No point in trying to allocate 991 // further. We'll just return NULL. 992 MutexLockerEx x(Heap_lock); 993 *gc_count_before_ret = total_collections(); 994 return NULL; 995 } 996 } else { 997 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 998 MutexLockerEx x(Heap_lock); 999 *gc_count_before_ret = total_collections(); 1000 return NULL; 1001 } 1002 // The GCLocker is either active or the GCLocker initiated 1003 // GC has not yet been performed. Stall until it is and 1004 // then retry the allocation. 1005 GC_locker::stall_until_clear(); 1006 (*gclocker_retry_count_ret) += 1; 1007 } 1008 1009 // We can reach here if we were unsuccessful in scheduling a 1010 // collection (because another thread beat us to it) or if we were 1011 // stalled due to the GC locker. In either can we should retry the 1012 // allocation attempt in case another thread successfully 1013 // performed a collection and reclaimed enough space. Give a 1014 // warning if we seem to be looping forever. 1015 1016 if ((QueuedAllocationWarningCount > 0) && 1017 (try_count % QueuedAllocationWarningCount == 0)) { 1018 warning("G1CollectedHeap::attempt_allocation_humongous() " 1019 "retries %d times", try_count); 1020 } 1021 } 1022 1023 ShouldNotReachHere(); 1024 return NULL; 1025 } 1026 1027 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1028 AllocationContext_t context, 1029 bool expect_null_mutator_alloc_region) { 1030 assert_at_safepoint(true /* should_be_vm_thread */); 1031 assert(_allocator->mutator_alloc_region(context)->get() == NULL || 1032 !expect_null_mutator_alloc_region, 1033 "the current alloc region was unexpectedly found to be non-NULL"); 1034 1035 if (!is_humongous(word_size)) { 1036 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, 1037 false /* bot_updates */); 1038 } else { 1039 HeapWord* result = humongous_obj_allocate(word_size, context); 1040 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1041 g1_policy()->set_initiate_conc_mark_if_possible(); 1042 } 1043 return result; 1044 } 1045 1046 ShouldNotReachHere(); 1047 } 1048 1049 class PostMCRemSetClearClosure: public HeapRegionClosure { 1050 G1CollectedHeap* _g1h; 1051 ModRefBarrierSet* _mr_bs; 1052 public: 1053 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1054 _g1h(g1h), _mr_bs(mr_bs) {} 1055 1056 bool doHeapRegion(HeapRegion* r) { 1057 HeapRegionRemSet* hrrs = r->rem_set(); 1058 1059 if (r->is_continues_humongous()) { 1060 // We'll assert that the strong code root list and RSet is empty 1061 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1062 assert(hrrs->occupied() == 0, "RSet should be empty"); 1063 return false; 1064 } 1065 1066 _g1h->reset_gc_time_stamps(r); 1067 hrrs->clear(); 1068 // You might think here that we could clear just the cards 1069 // corresponding to the used region. But no: if we leave a dirty card 1070 // in a region we might allocate into, then it would prevent that card 1071 // from being enqueued, and cause it to be missed. 1072 // Re: the performance cost: we shouldn't be doing full GC anyway! 1073 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1074 1075 return false; 1076 } 1077 }; 1078 1079 void G1CollectedHeap::clear_rsets_post_compaction() { 1080 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1081 heap_region_iterate(&rs_clear); 1082 } 1083 1084 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1085 G1CollectedHeap* _g1h; 1086 UpdateRSOopClosure _cl; 1087 public: 1088 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) : 1089 _cl(g1->g1_rem_set(), worker_i), 1090 _g1h(g1) 1091 { } 1092 1093 bool doHeapRegion(HeapRegion* r) { 1094 if (!r->is_continues_humongous()) { 1095 _cl.set_from(r); 1096 r->oop_iterate(&_cl); 1097 } 1098 return false; 1099 } 1100 }; 1101 1102 class ParRebuildRSTask: public AbstractGangTask { 1103 G1CollectedHeap* _g1; 1104 HeapRegionClaimer _hrclaimer; 1105 1106 public: 1107 ParRebuildRSTask(G1CollectedHeap* g1) : 1108 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {} 1109 1110 void work(uint worker_id) { 1111 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1112 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer); 1113 } 1114 }; 1115 1116 class PostCompactionPrinterClosure: public HeapRegionClosure { 1117 private: 1118 G1HRPrinter* _hr_printer; 1119 public: 1120 bool doHeapRegion(HeapRegion* hr) { 1121 assert(!hr->is_young(), "not expecting to find young regions"); 1122 if (hr->is_free()) { 1123 // We only generate output for non-empty regions. 1124 } else if (hr->is_starts_humongous()) { 1125 if (hr->region_num() == 1) { 1126 // single humongous region 1127 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1128 } else { 1129 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1130 } 1131 } else if (hr->is_continues_humongous()) { 1132 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1133 } else if (hr->is_old()) { 1134 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1135 } else { 1136 ShouldNotReachHere(); 1137 } 1138 return false; 1139 } 1140 1141 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1142 : _hr_printer(hr_printer) { } 1143 }; 1144 1145 void G1CollectedHeap::print_hrm_post_compaction() { 1146 PostCompactionPrinterClosure cl(hr_printer()); 1147 heap_region_iterate(&cl); 1148 } 1149 1150 bool G1CollectedHeap::do_collection(bool explicit_gc, 1151 bool clear_all_soft_refs, 1152 size_t word_size) { 1153 assert_at_safepoint(true /* should_be_vm_thread */); 1154 1155 if (GC_locker::check_active_before_gc()) { 1156 return false; 1157 } 1158 1159 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1160 gc_timer->register_gc_start(); 1161 1162 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1163 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1164 1165 SvcGCMarker sgcm(SvcGCMarker::FULL); 1166 ResourceMark rm; 1167 1168 G1Log::update_level(); 1169 print_heap_before_gc(); 1170 trace_heap_before_gc(gc_tracer); 1171 1172 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1173 1174 verify_region_sets_optional(); 1175 1176 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1177 collector_policy()->should_clear_all_soft_refs(); 1178 1179 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1180 1181 { 1182 IsGCActiveMark x; 1183 1184 // Timing 1185 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); 1186 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1187 1188 { 1189 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id()); 1190 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1191 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1192 1193 g1_policy()->record_full_collection_start(); 1194 1195 // Note: When we have a more flexible GC logging framework that 1196 // allows us to add optional attributes to a GC log record we 1197 // could consider timing and reporting how long we wait in the 1198 // following two methods. 1199 wait_while_free_regions_coming(); 1200 // If we start the compaction before the CM threads finish 1201 // scanning the root regions we might trip them over as we'll 1202 // be moving objects / updating references. So let's wait until 1203 // they are done. By telling them to abort, they should complete 1204 // early. 1205 _cm->root_regions()->abort(); 1206 _cm->root_regions()->wait_until_scan_finished(); 1207 append_secondary_free_list_if_not_empty_with_lock(); 1208 1209 gc_prologue(true); 1210 increment_total_collections(true /* full gc */); 1211 increment_old_marking_cycles_started(); 1212 1213 assert(used() == recalculate_used(), "Should be equal"); 1214 1215 verify_before_gc(); 1216 1217 check_bitmaps("Full GC Start"); 1218 pre_full_gc_dump(gc_timer); 1219 1220 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1221 1222 // Disable discovery and empty the discovered lists 1223 // for the CM ref processor. 1224 ref_processor_cm()->disable_discovery(); 1225 ref_processor_cm()->abandon_partial_discovery(); 1226 ref_processor_cm()->verify_no_references_recorded(); 1227 1228 // Abandon current iterations of concurrent marking and concurrent 1229 // refinement, if any are in progress. We have to do this before 1230 // wait_until_scan_finished() below. 1231 concurrent_mark()->abort(); 1232 1233 // Make sure we'll choose a new allocation region afterwards. 1234 _allocator->release_mutator_alloc_region(); 1235 _allocator->abandon_gc_alloc_regions(); 1236 g1_rem_set()->cleanupHRRS(); 1237 1238 // We should call this after we retire any currently active alloc 1239 // regions so that all the ALLOC / RETIRE events are generated 1240 // before the start GC event. 1241 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1242 1243 // We may have added regions to the current incremental collection 1244 // set between the last GC or pause and now. We need to clear the 1245 // incremental collection set and then start rebuilding it afresh 1246 // after this full GC. 1247 abandon_collection_set(g1_policy()->inc_cset_head()); 1248 g1_policy()->clear_incremental_cset(); 1249 g1_policy()->stop_incremental_cset_building(); 1250 1251 tear_down_region_sets(false /* free_list_only */); 1252 g1_policy()->set_gcs_are_young(true); 1253 1254 // See the comments in g1CollectedHeap.hpp and 1255 // G1CollectedHeap::ref_processing_init() about 1256 // how reference processing currently works in G1. 1257 1258 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1259 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1260 1261 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1262 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1263 1264 ref_processor_stw()->enable_discovery(); 1265 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1266 1267 // Do collection work 1268 { 1269 HandleMark hm; // Discard invalid handles created during gc 1270 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1271 } 1272 1273 assert(num_free_regions() == 0, "we should not have added any free regions"); 1274 rebuild_region_sets(false /* free_list_only */); 1275 1276 // Enqueue any discovered reference objects that have 1277 // not been removed from the discovered lists. 1278 ref_processor_stw()->enqueue_discovered_references(); 1279 1280 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1281 1282 MemoryService::track_memory_usage(); 1283 1284 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1285 ref_processor_stw()->verify_no_references_recorded(); 1286 1287 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1288 ClassLoaderDataGraph::purge(); 1289 MetaspaceAux::verify_metrics(); 1290 1291 // Note: since we've just done a full GC, concurrent 1292 // marking is no longer active. Therefore we need not 1293 // re-enable reference discovery for the CM ref processor. 1294 // That will be done at the start of the next marking cycle. 1295 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1296 ref_processor_cm()->verify_no_references_recorded(); 1297 1298 reset_gc_time_stamp(); 1299 // Since everything potentially moved, we will clear all remembered 1300 // sets, and clear all cards. Later we will rebuild remembered 1301 // sets. We will also reset the GC time stamps of the regions. 1302 clear_rsets_post_compaction(); 1303 check_gc_time_stamps(); 1304 1305 // Resize the heap if necessary. 1306 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1307 1308 if (_hr_printer.is_active()) { 1309 // We should do this after we potentially resize the heap so 1310 // that all the COMMIT / UNCOMMIT events are generated before 1311 // the end GC event. 1312 1313 print_hrm_post_compaction(); 1314 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1315 } 1316 1317 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1318 if (hot_card_cache->use_cache()) { 1319 hot_card_cache->reset_card_counts(); 1320 hot_card_cache->reset_hot_cache(); 1321 } 1322 1323 // Rebuild remembered sets of all regions. 1324 uint n_workers = 1325 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1326 workers()->active_workers(), 1327 Threads::number_of_non_daemon_threads()); 1328 assert(UseDynamicNumberOfGCThreads || 1329 n_workers == workers()->total_workers(), 1330 "If not dynamic should be using all the workers"); 1331 workers()->set_active_workers(n_workers); 1332 // Set parallel threads in the heap (_n_par_threads) only 1333 // before a parallel phase and always reset it to 0 after 1334 // the phase so that the number of parallel threads does 1335 // no get carried forward to a serial phase where there 1336 // may be code that is "possibly_parallel". 1337 set_par_threads(n_workers); 1338 1339 ParRebuildRSTask rebuild_rs_task(this); 1340 assert(UseDynamicNumberOfGCThreads || 1341 workers()->active_workers() == workers()->total_workers(), 1342 "Unless dynamic should use total workers"); 1343 // Use the most recent number of active workers 1344 assert(workers()->active_workers() > 0, 1345 "Active workers not properly set"); 1346 set_par_threads(workers()->active_workers()); 1347 workers()->run_task(&rebuild_rs_task); 1348 set_par_threads(0); 1349 1350 // Rebuild the strong code root lists for each region 1351 rebuild_strong_code_roots(); 1352 1353 if (true) { // FIXME 1354 MetaspaceGC::compute_new_size(); 1355 } 1356 1357 #ifdef TRACESPINNING 1358 ParallelTaskTerminator::print_termination_counts(); 1359 #endif 1360 1361 // Discard all rset updates 1362 JavaThread::dirty_card_queue_set().abandon_logs(); 1363 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1364 1365 _young_list->reset_sampled_info(); 1366 // At this point there should be no regions in the 1367 // entire heap tagged as young. 1368 assert(check_young_list_empty(true /* check_heap */), 1369 "young list should be empty at this point"); 1370 1371 // Update the number of full collections that have been completed. 1372 increment_old_marking_cycles_completed(false /* concurrent */); 1373 1374 _hrm.verify_optional(); 1375 verify_region_sets_optional(); 1376 1377 verify_after_gc(); 1378 1379 // Clear the previous marking bitmap, if needed for bitmap verification. 1380 // Note we cannot do this when we clear the next marking bitmap in 1381 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1382 // objects marked during a full GC against the previous bitmap. 1383 // But we need to clear it before calling check_bitmaps below since 1384 // the full GC has compacted objects and updated TAMS but not updated 1385 // the prev bitmap. 1386 if (G1VerifyBitmaps) { 1387 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1388 } 1389 check_bitmaps("Full GC End"); 1390 1391 // Start a new incremental collection set for the next pause 1392 assert(g1_policy()->collection_set() == NULL, "must be"); 1393 g1_policy()->start_incremental_cset_building(); 1394 1395 clear_cset_fast_test(); 1396 1397 _allocator->init_mutator_alloc_region(); 1398 1399 g1_policy()->record_full_collection_end(); 1400 1401 if (G1Log::fine()) { 1402 g1_policy()->print_heap_transition(); 1403 } 1404 1405 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1406 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1407 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1408 // before any GC notifications are raised. 1409 g1mm()->update_sizes(); 1410 1411 gc_epilogue(true); 1412 } 1413 1414 if (G1Log::finer()) { 1415 g1_policy()->print_detailed_heap_transition(true /* full */); 1416 } 1417 1418 print_heap_after_gc(); 1419 trace_heap_after_gc(gc_tracer); 1420 1421 post_full_gc_dump(gc_timer); 1422 1423 gc_timer->register_gc_end(); 1424 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1425 } 1426 1427 return true; 1428 } 1429 1430 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1431 // do_collection() will return whether it succeeded in performing 1432 // the GC. Currently, there is no facility on the 1433 // do_full_collection() API to notify the caller than the collection 1434 // did not succeed (e.g., because it was locked out by the GC 1435 // locker). So, right now, we'll ignore the return value. 1436 bool dummy = do_collection(true, /* explicit_gc */ 1437 clear_all_soft_refs, 1438 0 /* word_size */); 1439 } 1440 1441 // This code is mostly copied from TenuredGeneration. 1442 void 1443 G1CollectedHeap:: 1444 resize_if_necessary_after_full_collection(size_t word_size) { 1445 // Include the current allocation, if any, and bytes that will be 1446 // pre-allocated to support collections, as "used". 1447 const size_t used_after_gc = used(); 1448 const size_t capacity_after_gc = capacity(); 1449 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1450 1451 // This is enforced in arguments.cpp. 1452 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1453 "otherwise the code below doesn't make sense"); 1454 1455 // We don't have floating point command-line arguments 1456 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1457 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1458 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1459 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1460 1461 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1462 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1463 1464 // We have to be careful here as these two calculations can overflow 1465 // 32-bit size_t's. 1466 double used_after_gc_d = (double) used_after_gc; 1467 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1468 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1469 1470 // Let's make sure that they are both under the max heap size, which 1471 // by default will make them fit into a size_t. 1472 double desired_capacity_upper_bound = (double) max_heap_size; 1473 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1474 desired_capacity_upper_bound); 1475 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1476 desired_capacity_upper_bound); 1477 1478 // We can now safely turn them into size_t's. 1479 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1480 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1481 1482 // This assert only makes sense here, before we adjust them 1483 // with respect to the min and max heap size. 1484 assert(minimum_desired_capacity <= maximum_desired_capacity, 1485 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1486 "maximum_desired_capacity = "SIZE_FORMAT, 1487 minimum_desired_capacity, maximum_desired_capacity)); 1488 1489 // Should not be greater than the heap max size. No need to adjust 1490 // it with respect to the heap min size as it's a lower bound (i.e., 1491 // we'll try to make the capacity larger than it, not smaller). 1492 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1493 // Should not be less than the heap min size. No need to adjust it 1494 // with respect to the heap max size as it's an upper bound (i.e., 1495 // we'll try to make the capacity smaller than it, not greater). 1496 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1497 1498 if (capacity_after_gc < minimum_desired_capacity) { 1499 // Don't expand unless it's significant 1500 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1501 ergo_verbose4(ErgoHeapSizing, 1502 "attempt heap expansion", 1503 ergo_format_reason("capacity lower than " 1504 "min desired capacity after Full GC") 1505 ergo_format_byte("capacity") 1506 ergo_format_byte("occupancy") 1507 ergo_format_byte_perc("min desired capacity"), 1508 capacity_after_gc, used_after_gc, 1509 minimum_desired_capacity, (double) MinHeapFreeRatio); 1510 expand(expand_bytes); 1511 1512 // No expansion, now see if we want to shrink 1513 } else if (capacity_after_gc > maximum_desired_capacity) { 1514 // Capacity too large, compute shrinking size 1515 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1516 ergo_verbose4(ErgoHeapSizing, 1517 "attempt heap shrinking", 1518 ergo_format_reason("capacity higher than " 1519 "max desired capacity after Full GC") 1520 ergo_format_byte("capacity") 1521 ergo_format_byte("occupancy") 1522 ergo_format_byte_perc("max desired capacity"), 1523 capacity_after_gc, used_after_gc, 1524 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1525 shrink(shrink_bytes); 1526 } 1527 } 1528 1529 1530 HeapWord* 1531 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1532 AllocationContext_t context, 1533 bool* succeeded) { 1534 assert_at_safepoint(true /* should_be_vm_thread */); 1535 1536 *succeeded = true; 1537 // Let's attempt the allocation first. 1538 HeapWord* result = 1539 attempt_allocation_at_safepoint(word_size, 1540 context, 1541 false /* expect_null_mutator_alloc_region */); 1542 if (result != NULL) { 1543 assert(*succeeded, "sanity"); 1544 return result; 1545 } 1546 1547 // In a G1 heap, we're supposed to keep allocation from failing by 1548 // incremental pauses. Therefore, at least for now, we'll favor 1549 // expansion over collection. (This might change in the future if we can 1550 // do something smarter than full collection to satisfy a failed alloc.) 1551 result = expand_and_allocate(word_size, context); 1552 if (result != NULL) { 1553 assert(*succeeded, "sanity"); 1554 return result; 1555 } 1556 1557 // Expansion didn't work, we'll try to do a Full GC. 1558 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1559 false, /* clear_all_soft_refs */ 1560 word_size); 1561 if (!gc_succeeded) { 1562 *succeeded = false; 1563 return NULL; 1564 } 1565 1566 // Retry the allocation 1567 result = attempt_allocation_at_safepoint(word_size, 1568 context, 1569 true /* expect_null_mutator_alloc_region */); 1570 if (result != NULL) { 1571 assert(*succeeded, "sanity"); 1572 return result; 1573 } 1574 1575 // Then, try a Full GC that will collect all soft references. 1576 gc_succeeded = do_collection(false, /* explicit_gc */ 1577 true, /* clear_all_soft_refs */ 1578 word_size); 1579 if (!gc_succeeded) { 1580 *succeeded = false; 1581 return NULL; 1582 } 1583 1584 // Retry the allocation once more 1585 result = attempt_allocation_at_safepoint(word_size, 1586 context, 1587 true /* expect_null_mutator_alloc_region */); 1588 if (result != NULL) { 1589 assert(*succeeded, "sanity"); 1590 return result; 1591 } 1592 1593 assert(!collector_policy()->should_clear_all_soft_refs(), 1594 "Flag should have been handled and cleared prior to this point"); 1595 1596 // What else? We might try synchronous finalization later. If the total 1597 // space available is large enough for the allocation, then a more 1598 // complete compaction phase than we've tried so far might be 1599 // appropriate. 1600 assert(*succeeded, "sanity"); 1601 return NULL; 1602 } 1603 1604 // Attempting to expand the heap sufficiently 1605 // to support an allocation of the given "word_size". If 1606 // successful, perform the allocation and return the address of the 1607 // allocated block, or else "NULL". 1608 1609 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1610 assert_at_safepoint(true /* should_be_vm_thread */); 1611 1612 verify_region_sets_optional(); 1613 1614 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1615 ergo_verbose1(ErgoHeapSizing, 1616 "attempt heap expansion", 1617 ergo_format_reason("allocation request failed") 1618 ergo_format_byte("allocation request"), 1619 word_size * HeapWordSize); 1620 if (expand(expand_bytes)) { 1621 _hrm.verify_optional(); 1622 verify_region_sets_optional(); 1623 return attempt_allocation_at_safepoint(word_size, 1624 context, 1625 false /* expect_null_mutator_alloc_region */); 1626 } 1627 return NULL; 1628 } 1629 1630 bool G1CollectedHeap::expand(size_t expand_bytes) { 1631 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1632 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1633 HeapRegion::GrainBytes); 1634 ergo_verbose2(ErgoHeapSizing, 1635 "expand the heap", 1636 ergo_format_byte("requested expansion amount") 1637 ergo_format_byte("attempted expansion amount"), 1638 expand_bytes, aligned_expand_bytes); 1639 1640 if (is_maximal_no_gc()) { 1641 ergo_verbose0(ErgoHeapSizing, 1642 "did not expand the heap", 1643 ergo_format_reason("heap already fully expanded")); 1644 return false; 1645 } 1646 1647 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1648 assert(regions_to_expand > 0, "Must expand by at least one region"); 1649 1650 uint expanded_by = _hrm.expand_by(regions_to_expand); 1651 1652 if (expanded_by > 0) { 1653 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1654 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1655 g1_policy()->record_new_heap_size(num_regions()); 1656 } else { 1657 ergo_verbose0(ErgoHeapSizing, 1658 "did not expand the heap", 1659 ergo_format_reason("heap expansion operation failed")); 1660 // The expansion of the virtual storage space was unsuccessful. 1661 // Let's see if it was because we ran out of swap. 1662 if (G1ExitOnExpansionFailure && 1663 _hrm.available() >= regions_to_expand) { 1664 // We had head room... 1665 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1666 } 1667 } 1668 return regions_to_expand > 0; 1669 } 1670 1671 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1672 size_t aligned_shrink_bytes = 1673 ReservedSpace::page_align_size_down(shrink_bytes); 1674 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1675 HeapRegion::GrainBytes); 1676 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1677 1678 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1679 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1680 1681 ergo_verbose3(ErgoHeapSizing, 1682 "shrink the heap", 1683 ergo_format_byte("requested shrinking amount") 1684 ergo_format_byte("aligned shrinking amount") 1685 ergo_format_byte("attempted shrinking amount"), 1686 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1687 if (num_regions_removed > 0) { 1688 g1_policy()->record_new_heap_size(num_regions()); 1689 } else { 1690 ergo_verbose0(ErgoHeapSizing, 1691 "did not shrink the heap", 1692 ergo_format_reason("heap shrinking operation failed")); 1693 } 1694 } 1695 1696 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1697 verify_region_sets_optional(); 1698 1699 // We should only reach here at the end of a Full GC which means we 1700 // should not not be holding to any GC alloc regions. The method 1701 // below will make sure of that and do any remaining clean up. 1702 _allocator->abandon_gc_alloc_regions(); 1703 1704 // Instead of tearing down / rebuilding the free lists here, we 1705 // could instead use the remove_all_pending() method on free_list to 1706 // remove only the ones that we need to remove. 1707 tear_down_region_sets(true /* free_list_only */); 1708 shrink_helper(shrink_bytes); 1709 rebuild_region_sets(true /* free_list_only */); 1710 1711 _hrm.verify_optional(); 1712 verify_region_sets_optional(); 1713 } 1714 1715 // Public methods. 1716 1717 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1718 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1719 #endif // _MSC_VER 1720 1721 1722 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1723 CollectedHeap(), 1724 _g1_policy(policy_), 1725 _dirty_card_queue_set(false), 1726 _into_cset_dirty_card_queue_set(false), 1727 _is_alive_closure_cm(this), 1728 _is_alive_closure_stw(this), 1729 _ref_processor_cm(NULL), 1730 _ref_processor_stw(NULL), 1731 _bot_shared(NULL), 1732 _evac_failure_scan_stack(NULL), 1733 _mark_in_progress(false), 1734 _cg1r(NULL), 1735 _g1mm(NULL), 1736 _refine_cte_cl(NULL), 1737 _full_collection(false), 1738 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1739 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1740 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1741 _humongous_reclaim_candidates(), 1742 _has_humongous_reclaim_candidates(false), 1743 _free_regions_coming(false), 1744 _young_list(new YoungList(this)), 1745 _gc_time_stamp(0), 1746 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1747 _old_plab_stats(OldPLABSize, PLABWeight), 1748 _expand_heap_after_alloc_failure(true), 1749 _surviving_young_words(NULL), 1750 _old_marking_cycles_started(0), 1751 _old_marking_cycles_completed(0), 1752 _concurrent_cycle_started(false), 1753 _heap_summary_sent(false), 1754 _in_cset_fast_test(), 1755 _dirty_cards_region_list(NULL), 1756 _worker_cset_start_region(NULL), 1757 _worker_cset_start_region_time_stamp(NULL), 1758 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1759 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1760 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1761 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1762 1763 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads, 1764 /* are_GC_task_threads */true, 1765 /* are_ConcurrentGC_threads */false); 1766 _workers->initialize_workers(); 1767 1768 _allocator = G1Allocator::create_allocator(this); 1769 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1770 1771 int n_queues = MAX2((int)ParallelGCThreads, 1); 1772 _task_queues = new RefToScanQueueSet(n_queues); 1773 1774 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1775 assert(n_rem_sets > 0, "Invariant."); 1776 1777 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1778 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC); 1779 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1780 1781 for (int i = 0; i < n_queues; i++) { 1782 RefToScanQueue* q = new RefToScanQueue(); 1783 q->initialize(); 1784 _task_queues->register_queue(i, q); 1785 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1786 } 1787 clear_cset_start_regions(); 1788 1789 // Initialize the G1EvacuationFailureALot counters and flags. 1790 NOT_PRODUCT(reset_evacuation_should_fail();) 1791 1792 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1793 } 1794 1795 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1796 size_t size, 1797 size_t translation_factor) { 1798 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1799 // Allocate a new reserved space, preferring to use large pages. 1800 ReservedSpace rs(size, preferred_page_size); 1801 G1RegionToSpaceMapper* result = 1802 G1RegionToSpaceMapper::create_mapper(rs, 1803 size, 1804 rs.alignment(), 1805 HeapRegion::GrainBytes, 1806 translation_factor, 1807 mtGC); 1808 if (TracePageSizes) { 1809 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT, 1810 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size); 1811 } 1812 return result; 1813 } 1814 1815 jint G1CollectedHeap::initialize() { 1816 CollectedHeap::pre_initialize(); 1817 os::enable_vtime(); 1818 1819 G1Log::init(); 1820 1821 // Necessary to satisfy locking discipline assertions. 1822 1823 MutexLocker x(Heap_lock); 1824 1825 // We have to initialize the printer before committing the heap, as 1826 // it will be used then. 1827 _hr_printer.set_active(G1PrintHeapRegions); 1828 1829 // While there are no constraints in the GC code that HeapWordSize 1830 // be any particular value, there are multiple other areas in the 1831 // system which believe this to be true (e.g. oop->object_size in some 1832 // cases incorrectly returns the size in wordSize units rather than 1833 // HeapWordSize). 1834 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1835 1836 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1837 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1838 size_t heap_alignment = collector_policy()->heap_alignment(); 1839 1840 // Ensure that the sizes are properly aligned. 1841 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1842 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1843 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1844 1845 _refine_cte_cl = new RefineCardTableEntryClosure(); 1846 1847 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl); 1848 1849 // Reserve the maximum. 1850 1851 // When compressed oops are enabled, the preferred heap base 1852 // is calculated by subtracting the requested size from the 1853 // 32Gb boundary and using the result as the base address for 1854 // heap reservation. If the requested size is not aligned to 1855 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1856 // into the ReservedHeapSpace constructor) then the actual 1857 // base of the reserved heap may end up differing from the 1858 // address that was requested (i.e. the preferred heap base). 1859 // If this happens then we could end up using a non-optimal 1860 // compressed oops mode. 1861 1862 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1863 heap_alignment); 1864 1865 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1866 1867 // Create the barrier set for the entire reserved region. 1868 G1SATBCardTableLoggingModRefBS* bs 1869 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 1870 bs->initialize(); 1871 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 1872 set_barrier_set(bs); 1873 1874 // Also create a G1 rem set. 1875 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 1876 1877 // Carve out the G1 part of the heap. 1878 1879 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1880 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 1881 G1RegionToSpaceMapper* heap_storage = 1882 G1RegionToSpaceMapper::create_mapper(g1_rs, 1883 g1_rs.size(), 1884 page_size, 1885 HeapRegion::GrainBytes, 1886 1, 1887 mtJavaHeap); 1888 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(), 1889 max_byte_size, page_size, 1890 heap_rs.base(), 1891 heap_rs.size()); 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::heap_map_factor()); 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 G1SATBCardTableLoggingModRefBS::heap_map_factor()); 1905 1906 G1RegionToSpaceMapper* card_counts_storage = 1907 create_aux_memory_mapper("Card counts table", 1908 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1909 G1CardCounts::heap_map_factor()); 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::heap_map_factor()); 1914 G1RegionToSpaceMapper* next_bitmap_storage = 1915 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor()); 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, p2i(p), p2i(obj)); 2756 if (_vo == VerifyOption_G1UseMarkWord) { 2757 gclog_or_tty->print_cr(" Mark word: "INTPTR_FORMAT, (intptr_t)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 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(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.", p2i(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 VerifyRegionClosure: public HeapRegionClosure { 2925 private: 2926 bool _par; 2927 VerifyOption _vo; 2928 bool _failures; 2929 public: 2930 // _vo == UsePrevMarking -> use "prev" marking information, 2931 // _vo == UseNextMarking -> use "next" marking information, 2932 // _vo == UseMarkWord -> use mark word from object header. 2933 VerifyRegionClosure(bool par, VerifyOption vo) 2934 : _par(par), 2935 _vo(vo), 2936 _failures(false) {} 2937 2938 bool failures() { 2939 return _failures; 2940 } 2941 2942 bool doHeapRegion(HeapRegion* r) { 2943 if (!r->is_continues_humongous()) { 2944 bool failures = false; 2945 r->verify(_vo, &failures); 2946 if (failures) { 2947 _failures = true; 2948 } else { 2949 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 2950 r->object_iterate(¬_dead_yet_cl); 2951 if (_vo != VerifyOption_G1UseNextMarking) { 2952 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 2953 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 2954 "max_live_bytes "SIZE_FORMAT" " 2955 "< calculated "SIZE_FORMAT, 2956 p2i(r->bottom()), p2i(r->end()), 2957 r->max_live_bytes(), 2958 not_dead_yet_cl.live_bytes()); 2959 _failures = true; 2960 } 2961 } else { 2962 // When vo == UseNextMarking we cannot currently do a sanity 2963 // check on the live bytes as the calculation has not been 2964 // finalized yet. 2965 } 2966 } 2967 } 2968 return false; // stop the region iteration if we hit a failure 2969 } 2970 }; 2971 2972 // This is the task used for parallel verification of the heap regions 2973 2974 class G1ParVerifyTask: public AbstractGangTask { 2975 private: 2976 G1CollectedHeap* _g1h; 2977 VerifyOption _vo; 2978 bool _failures; 2979 HeapRegionClaimer _hrclaimer; 2980 2981 public: 2982 // _vo == UsePrevMarking -> use "prev" marking information, 2983 // _vo == UseNextMarking -> use "next" marking information, 2984 // _vo == UseMarkWord -> use mark word from object header. 2985 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 2986 AbstractGangTask("Parallel verify task"), 2987 _g1h(g1h), 2988 _vo(vo), 2989 _failures(false), 2990 _hrclaimer(g1h->workers()->active_workers()) {} 2991 2992 bool failures() { 2993 return _failures; 2994 } 2995 2996 void work(uint worker_id) { 2997 HandleMark hm; 2998 VerifyRegionClosure blk(true, _vo); 2999 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer); 3000 if (blk.failures()) { 3001 _failures = true; 3002 } 3003 } 3004 }; 3005 3006 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3007 if (SafepointSynchronize::is_at_safepoint()) { 3008 assert(Thread::current()->is_VM_thread(), 3009 "Expected to be executed serially by the VM thread at this point"); 3010 3011 if (!silent) { gclog_or_tty->print("Roots "); } 3012 VerifyRootsClosure rootsCl(vo); 3013 VerifyKlassClosure klassCl(this, &rootsCl); 3014 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3015 3016 // We apply the relevant closures to all the oops in the 3017 // system dictionary, class loader data graph, the string table 3018 // and the nmethods in the code cache. 3019 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3020 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3021 3022 { 3023 G1RootProcessor root_processor(this, 1); 3024 root_processor.process_all_roots(&rootsCl, 3025 &cldCl, 3026 &blobsCl); 3027 } 3028 3029 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3030 3031 if (vo != VerifyOption_G1UseMarkWord) { 3032 // If we're verifying during a full GC then the region sets 3033 // will have been torn down at the start of the GC. Therefore 3034 // verifying the region sets will fail. So we only verify 3035 // the region sets when not in a full GC. 3036 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3037 verify_region_sets(); 3038 } 3039 3040 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3041 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3042 3043 G1ParVerifyTask task(this, vo); 3044 assert(UseDynamicNumberOfGCThreads || 3045 workers()->active_workers() == workers()->total_workers(), 3046 "If not dynamic should be using all the workers"); 3047 uint n_workers = workers()->active_workers(); 3048 set_par_threads(n_workers); 3049 workers()->run_task(&task); 3050 set_par_threads(0); 3051 if (task.failures()) { 3052 failures = true; 3053 } 3054 3055 } else { 3056 VerifyRegionClosure blk(false, vo); 3057 heap_region_iterate(&blk); 3058 if (blk.failures()) { 3059 failures = true; 3060 } 3061 } 3062 3063 if (G1StringDedup::is_enabled()) { 3064 if (!silent) gclog_or_tty->print("StrDedup "); 3065 G1StringDedup::verify(); 3066 } 3067 3068 if (failures) { 3069 gclog_or_tty->print_cr("Heap:"); 3070 // It helps to have the per-region information in the output to 3071 // help us track down what went wrong. This is why we call 3072 // print_extended_on() instead of print_on(). 3073 print_extended_on(gclog_or_tty); 3074 gclog_or_tty->cr(); 3075 gclog_or_tty->flush(); 3076 } 3077 guarantee(!failures, "there should not have been any failures"); 3078 } else { 3079 if (!silent) { 3080 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3081 if (G1StringDedup::is_enabled()) { 3082 gclog_or_tty->print(", StrDedup"); 3083 } 3084 gclog_or_tty->print(") "); 3085 } 3086 } 3087 } 3088 3089 void G1CollectedHeap::verify(bool silent) { 3090 verify(silent, VerifyOption_G1UsePrevMarking); 3091 } 3092 3093 double G1CollectedHeap::verify(bool guard, const char* msg) { 3094 double verify_time_ms = 0.0; 3095 3096 if (guard && total_collections() >= VerifyGCStartAt) { 3097 double verify_start = os::elapsedTime(); 3098 HandleMark hm; // Discard invalid handles created during verification 3099 prepare_for_verify(); 3100 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3101 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3102 } 3103 3104 return verify_time_ms; 3105 } 3106 3107 void G1CollectedHeap::verify_before_gc() { 3108 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3109 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3110 } 3111 3112 void G1CollectedHeap::verify_after_gc() { 3113 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3114 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3115 } 3116 3117 class PrintRegionClosure: public HeapRegionClosure { 3118 outputStream* _st; 3119 public: 3120 PrintRegionClosure(outputStream* st) : _st(st) {} 3121 bool doHeapRegion(HeapRegion* r) { 3122 r->print_on(_st); 3123 return false; 3124 } 3125 }; 3126 3127 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3128 const HeapRegion* hr, 3129 const VerifyOption vo) const { 3130 switch (vo) { 3131 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3132 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3133 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3134 default: ShouldNotReachHere(); 3135 } 3136 return false; // keep some compilers happy 3137 } 3138 3139 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3140 const VerifyOption vo) const { 3141 switch (vo) { 3142 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3143 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3144 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3145 default: ShouldNotReachHere(); 3146 } 3147 return false; // keep some compilers happy 3148 } 3149 3150 void G1CollectedHeap::print_on(outputStream* st) const { 3151 st->print(" %-20s", "garbage-first heap"); 3152 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3153 capacity()/K, used_unlocked()/K); 3154 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")", 3155 p2i(_hrm.reserved().start()), 3156 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords), 3157 p2i(_hrm.reserved().end())); 3158 st->cr(); 3159 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3160 uint young_regions = _young_list->length(); 3161 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3162 (size_t) young_regions * HeapRegion::GrainBytes / K); 3163 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3164 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3165 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3166 st->cr(); 3167 MetaspaceAux::print_on(st); 3168 } 3169 3170 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3171 print_on(st); 3172 3173 // Print the per-region information. 3174 st->cr(); 3175 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3176 "HS=humongous(starts), HC=humongous(continues), " 3177 "CS=collection set, F=free, TS=gc time stamp, " 3178 "PTAMS=previous top-at-mark-start, " 3179 "NTAMS=next top-at-mark-start)"); 3180 PrintRegionClosure blk(st); 3181 heap_region_iterate(&blk); 3182 } 3183 3184 void G1CollectedHeap::print_on_error(outputStream* st) const { 3185 this->CollectedHeap::print_on_error(st); 3186 3187 if (_cm != NULL) { 3188 st->cr(); 3189 _cm->print_on_error(st); 3190 } 3191 } 3192 3193 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3194 workers()->print_worker_threads_on(st); 3195 _cmThread->print_on(st); 3196 st->cr(); 3197 _cm->print_worker_threads_on(st); 3198 _cg1r->print_worker_threads_on(st); 3199 if (G1StringDedup::is_enabled()) { 3200 G1StringDedup::print_worker_threads_on(st); 3201 } 3202 } 3203 3204 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3205 workers()->threads_do(tc); 3206 tc->do_thread(_cmThread); 3207 _cg1r->threads_do(tc); 3208 if (G1StringDedup::is_enabled()) { 3209 G1StringDedup::threads_do(tc); 3210 } 3211 } 3212 3213 void G1CollectedHeap::print_tracing_info() const { 3214 // We'll overload this to mean "trace GC pause statistics." 3215 if (TraceYoungGenTime || TraceOldGenTime) { 3216 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3217 // to that. 3218 g1_policy()->print_tracing_info(); 3219 } 3220 if (G1SummarizeRSetStats) { 3221 g1_rem_set()->print_summary_info(); 3222 } 3223 if (G1SummarizeConcMark) { 3224 concurrent_mark()->print_summary_info(); 3225 } 3226 g1_policy()->print_yg_surv_rate_info(); 3227 } 3228 3229 #ifndef PRODUCT 3230 // Helpful for debugging RSet issues. 3231 3232 class PrintRSetsClosure : public HeapRegionClosure { 3233 private: 3234 const char* _msg; 3235 size_t _occupied_sum; 3236 3237 public: 3238 bool doHeapRegion(HeapRegion* r) { 3239 HeapRegionRemSet* hrrs = r->rem_set(); 3240 size_t occupied = hrrs->occupied(); 3241 _occupied_sum += occupied; 3242 3243 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3244 HR_FORMAT_PARAMS(r)); 3245 if (occupied == 0) { 3246 gclog_or_tty->print_cr(" RSet is empty"); 3247 } else { 3248 hrrs->print(); 3249 } 3250 gclog_or_tty->print_cr("----------"); 3251 return false; 3252 } 3253 3254 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3255 gclog_or_tty->cr(); 3256 gclog_or_tty->print_cr("========================================"); 3257 gclog_or_tty->print_cr("%s", msg); 3258 gclog_or_tty->cr(); 3259 } 3260 3261 ~PrintRSetsClosure() { 3262 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3263 gclog_or_tty->print_cr("========================================"); 3264 gclog_or_tty->cr(); 3265 } 3266 }; 3267 3268 void G1CollectedHeap::print_cset_rsets() { 3269 PrintRSetsClosure cl("Printing CSet RSets"); 3270 collection_set_iterate(&cl); 3271 } 3272 3273 void G1CollectedHeap::print_all_rsets() { 3274 PrintRSetsClosure cl("Printing All RSets");; 3275 heap_region_iterate(&cl); 3276 } 3277 #endif // PRODUCT 3278 3279 G1CollectedHeap* G1CollectedHeap::heap() { 3280 CollectedHeap* heap = Universe::heap(); 3281 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 3282 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); 3283 return (G1CollectedHeap*)heap; 3284 } 3285 3286 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3287 // always_do_update_barrier = false; 3288 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3289 // Fill TLAB's and such 3290 accumulate_statistics_all_tlabs(); 3291 ensure_parsability(true); 3292 3293 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3294 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3295 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3296 } 3297 } 3298 3299 void G1CollectedHeap::gc_epilogue(bool full) { 3300 3301 if (G1SummarizeRSetStats && 3302 (G1SummarizeRSetStatsPeriod > 0) && 3303 // we are at the end of the GC. Total collections has already been increased. 3304 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3305 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3306 } 3307 3308 // FIXME: what is this about? 3309 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3310 // is set. 3311 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3312 "derived pointer present")); 3313 // always_do_update_barrier = true; 3314 3315 resize_all_tlabs(); 3316 allocation_context_stats().update(full); 3317 3318 // We have just completed a GC. Update the soft reference 3319 // policy with the new heap occupancy 3320 Universe::update_heap_info_at_gc(); 3321 } 3322 3323 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3324 uint gc_count_before, 3325 bool* succeeded, 3326 GCCause::Cause gc_cause) { 3327 assert_heap_not_locked_and_not_at_safepoint(); 3328 g1_policy()->record_stop_world_start(); 3329 VM_G1IncCollectionPause op(gc_count_before, 3330 word_size, 3331 false, /* should_initiate_conc_mark */ 3332 g1_policy()->max_pause_time_ms(), 3333 gc_cause); 3334 3335 op.set_allocation_context(AllocationContext::current()); 3336 VMThread::execute(&op); 3337 3338 HeapWord* result = op.result(); 3339 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3340 assert(result == NULL || ret_succeeded, 3341 "the result should be NULL if the VM did not succeed"); 3342 *succeeded = ret_succeeded; 3343 3344 assert_heap_not_locked(); 3345 return result; 3346 } 3347 3348 void 3349 G1CollectedHeap::doConcurrentMark() { 3350 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3351 if (!_cmThread->in_progress()) { 3352 _cmThread->set_started(); 3353 CGC_lock->notify(); 3354 } 3355 } 3356 3357 size_t G1CollectedHeap::pending_card_num() { 3358 size_t extra_cards = 0; 3359 JavaThread *curr = Threads::first(); 3360 while (curr != NULL) { 3361 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3362 extra_cards += dcq.size(); 3363 curr = curr->next(); 3364 } 3365 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3366 size_t buffer_size = dcqs.buffer_size(); 3367 size_t buffer_num = dcqs.completed_buffers_num(); 3368 3369 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3370 // in bytes - not the number of 'entries'. We need to convert 3371 // into a number of cards. 3372 return (buffer_size * buffer_num + extra_cards) / oopSize; 3373 } 3374 3375 size_t G1CollectedHeap::cards_scanned() { 3376 return g1_rem_set()->cardsScanned(); 3377 } 3378 3379 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3380 private: 3381 size_t _total_humongous; 3382 size_t _candidate_humongous; 3383 3384 DirtyCardQueue _dcq; 3385 3386 // We don't nominate objects with many remembered set entries, on 3387 // the assumption that such objects are likely still live. 3388 bool is_remset_small(HeapRegion* region) const { 3389 HeapRegionRemSet* const rset = region->rem_set(); 3390 return G1EagerReclaimHumongousObjectsWithStaleRefs 3391 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) 3392 : rset->is_empty(); 3393 } 3394 3395 bool is_typeArray_region(HeapRegion* region) const { 3396 return oop(region->bottom())->is_typeArray(); 3397 } 3398 3399 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { 3400 assert(region->is_starts_humongous(), "Must start a humongous object"); 3401 3402 // Candidate selection must satisfy the following constraints 3403 // while concurrent marking is in progress: 3404 // 3405 // * In order to maintain SATB invariants, an object must not be 3406 // reclaimed if it was allocated before the start of marking and 3407 // has not had its references scanned. Such an object must have 3408 // its references (including type metadata) scanned to ensure no 3409 // live objects are missed by the marking process. Objects 3410 // allocated after the start of concurrent marking don't need to 3411 // be scanned. 3412 // 3413 // * An object must not be reclaimed if it is on the concurrent 3414 // mark stack. Objects allocated after the start of concurrent 3415 // marking are never pushed on the mark stack. 3416 // 3417 // Nominating only objects allocated after the start of concurrent 3418 // marking is sufficient to meet both constraints. This may miss 3419 // some objects that satisfy the constraints, but the marking data 3420 // structures don't support efficiently performing the needed 3421 // additional tests or scrubbing of the mark stack. 3422 // 3423 // However, we presently only nominate is_typeArray() objects. 3424 // A humongous object containing references induces remembered 3425 // set entries on other regions. In order to reclaim such an 3426 // object, those remembered sets would need to be cleaned up. 3427 // 3428 // We also treat is_typeArray() objects specially, allowing them 3429 // to be reclaimed even if allocated before the start of 3430 // concurrent mark. For this we rely on mark stack insertion to 3431 // exclude is_typeArray() objects, preventing reclaiming an object 3432 // that is in the mark stack. We also rely on the metadata for 3433 // such objects to be built-in and so ensured to be kept live. 3434 // Frequent allocation and drop of large binary blobs is an 3435 // important use case for eager reclaim, and this special handling 3436 // may reduce needed headroom. 3437 3438 return is_typeArray_region(region) && is_remset_small(region); 3439 } 3440 3441 public: 3442 RegisterHumongousWithInCSetFastTestClosure() 3443 : _total_humongous(0), 3444 _candidate_humongous(0), 3445 _dcq(&JavaThread::dirty_card_queue_set()) { 3446 } 3447 3448 virtual bool doHeapRegion(HeapRegion* r) { 3449 if (!r->is_starts_humongous()) { 3450 return false; 3451 } 3452 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3453 3454 bool is_candidate = humongous_region_is_candidate(g1h, r); 3455 uint rindex = r->hrm_index(); 3456 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 3457 if (is_candidate) { 3458 _candidate_humongous++; 3459 g1h->register_humongous_region_with_cset(rindex); 3460 // Is_candidate already filters out humongous object with large remembered sets. 3461 // If we have a humongous object with a few remembered sets, we simply flush these 3462 // remembered set entries into the DCQS. That will result in automatic 3463 // re-evaluation of their remembered set entries during the following evacuation 3464 // phase. 3465 if (!r->rem_set()->is_empty()) { 3466 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 3467 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 3468 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 3469 HeapRegionRemSetIterator hrrs(r->rem_set()); 3470 size_t card_index; 3471 while (hrrs.has_next(card_index)) { 3472 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 3473 // The remembered set might contain references to already freed 3474 // regions. Filter out such entries to avoid failing card table 3475 // verification. 3476 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) { 3477 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 3478 *card_ptr = CardTableModRefBS::dirty_card_val(); 3479 _dcq.enqueue(card_ptr); 3480 } 3481 } 3482 } 3483 r->rem_set()->clear_locked(); 3484 } 3485 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 3486 } 3487 _total_humongous++; 3488 3489 return false; 3490 } 3491 3492 size_t total_humongous() const { return _total_humongous; } 3493 size_t candidate_humongous() const { return _candidate_humongous; } 3494 3495 void flush_rem_set_entries() { _dcq.flush(); } 3496 }; 3497 3498 void G1CollectedHeap::register_humongous_regions_with_cset() { 3499 if (!G1EagerReclaimHumongousObjects) { 3500 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 3501 return; 3502 } 3503 double time = os::elapsed_counter(); 3504 3505 // Collect reclaim candidate information and register candidates with cset. 3506 RegisterHumongousWithInCSetFastTestClosure cl; 3507 heap_region_iterate(&cl); 3508 3509 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 3510 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 3511 cl.total_humongous(), 3512 cl.candidate_humongous()); 3513 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3514 3515 // Finally flush all remembered set entries to re-check into the global DCQS. 3516 cl.flush_rem_set_entries(); 3517 } 3518 3519 void 3520 G1CollectedHeap::setup_surviving_young_words() { 3521 assert(_surviving_young_words == NULL, "pre-condition"); 3522 uint array_length = g1_policy()->young_cset_region_length(); 3523 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3524 if (_surviving_young_words == NULL) { 3525 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3526 "Not enough space for young surv words summary."); 3527 } 3528 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3529 #ifdef ASSERT 3530 for (uint i = 0; i < array_length; ++i) { 3531 assert( _surviving_young_words[i] == 0, "memset above" ); 3532 } 3533 #endif // !ASSERT 3534 } 3535 3536 void 3537 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3538 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3539 uint array_length = g1_policy()->young_cset_region_length(); 3540 for (uint i = 0; i < array_length; ++i) { 3541 _surviving_young_words[i] += surv_young_words[i]; 3542 } 3543 } 3544 3545 void 3546 G1CollectedHeap::cleanup_surviving_young_words() { 3547 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3548 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words); 3549 _surviving_young_words = NULL; 3550 } 3551 3552 #ifdef ASSERT 3553 class VerifyCSetClosure: public HeapRegionClosure { 3554 public: 3555 bool doHeapRegion(HeapRegion* hr) { 3556 // Here we check that the CSet region's RSet is ready for parallel 3557 // iteration. The fields that we'll verify are only manipulated 3558 // when the region is part of a CSet and is collected. Afterwards, 3559 // we reset these fields when we clear the region's RSet (when the 3560 // region is freed) so they are ready when the region is 3561 // re-allocated. The only exception to this is if there's an 3562 // evacuation failure and instead of freeing the region we leave 3563 // it in the heap. In that case, we reset these fields during 3564 // evacuation failure handling. 3565 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3566 3567 // Here's a good place to add any other checks we'd like to 3568 // perform on CSet regions. 3569 return false; 3570 } 3571 }; 3572 #endif // ASSERT 3573 3574 #if TASKQUEUE_STATS 3575 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3576 st->print_raw_cr("GC Task Stats"); 3577 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3578 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3579 } 3580 3581 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3582 print_taskqueue_stats_hdr(st); 3583 3584 TaskQueueStats totals; 3585 const uint n = workers()->total_workers(); 3586 for (uint i = 0; i < n; ++i) { 3587 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 3588 totals += task_queue(i)->stats; 3589 } 3590 st->print_raw("tot "); totals.print(st); st->cr(); 3591 3592 DEBUG_ONLY(totals.verify()); 3593 } 3594 3595 void G1CollectedHeap::reset_taskqueue_stats() { 3596 const uint n = workers()->total_workers(); 3597 for (uint i = 0; i < n; ++i) { 3598 task_queue(i)->stats.reset(); 3599 } 3600 } 3601 #endif // TASKQUEUE_STATS 3602 3603 void G1CollectedHeap::log_gc_header() { 3604 if (!G1Log::fine()) { 3605 return; 3606 } 3607 3608 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id()); 3609 3610 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3611 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") 3612 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3613 3614 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3615 } 3616 3617 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3618 if (!G1Log::fine()) { 3619 return; 3620 } 3621 3622 if (G1Log::finer()) { 3623 if (evacuation_failed()) { 3624 gclog_or_tty->print(" (to-space exhausted)"); 3625 } 3626 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3627 g1_policy()->phase_times()->note_gc_end(); 3628 g1_policy()->phase_times()->print(pause_time_sec); 3629 g1_policy()->print_detailed_heap_transition(); 3630 } else { 3631 if (evacuation_failed()) { 3632 gclog_or_tty->print("--"); 3633 } 3634 g1_policy()->print_heap_transition(); 3635 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3636 } 3637 gclog_or_tty->flush(); 3638 } 3639 3640 bool 3641 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3642 assert_at_safepoint(true /* should_be_vm_thread */); 3643 guarantee(!is_gc_active(), "collection is not reentrant"); 3644 3645 if (GC_locker::check_active_before_gc()) { 3646 return false; 3647 } 3648 3649 _gc_timer_stw->register_gc_start(); 3650 3651 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3652 3653 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3654 ResourceMark rm; 3655 3656 G1Log::update_level(); 3657 print_heap_before_gc(); 3658 trace_heap_before_gc(_gc_tracer_stw); 3659 3660 verify_region_sets_optional(); 3661 verify_dirty_young_regions(); 3662 3663 // This call will decide whether this pause is an initial-mark 3664 // pause. If it is, during_initial_mark_pause() will return true 3665 // for the duration of this pause. 3666 g1_policy()->decide_on_conc_mark_initiation(); 3667 3668 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3669 assert(!g1_policy()->during_initial_mark_pause() || 3670 g1_policy()->gcs_are_young(), "sanity"); 3671 3672 // We also do not allow mixed GCs during marking. 3673 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3674 3675 // Record whether this pause is an initial mark. When the current 3676 // thread has completed its logging output and it's safe to signal 3677 // the CM thread, the flag's value in the policy has been reset. 3678 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3679 3680 // Inner scope for scope based logging, timers, and stats collection 3681 { 3682 EvacuationInfo evacuation_info; 3683 3684 if (g1_policy()->during_initial_mark_pause()) { 3685 // We are about to start a marking cycle, so we increment the 3686 // full collection counter. 3687 increment_old_marking_cycles_started(); 3688 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3689 } 3690 3691 _gc_tracer_stw->report_yc_type(yc_type()); 3692 3693 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3694 3695 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 3696 workers()->active_workers(), 3697 Threads::number_of_non_daemon_threads()); 3698 assert(UseDynamicNumberOfGCThreads || 3699 active_workers == workers()->total_workers(), 3700 "If not dynamic should be using all the workers"); 3701 workers()->set_active_workers(active_workers); 3702 3703 double pause_start_sec = os::elapsedTime(); 3704 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress()); 3705 log_gc_header(); 3706 3707 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3708 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3709 3710 // If the secondary_free_list is not empty, append it to the 3711 // free_list. No need to wait for the cleanup operation to finish; 3712 // the region allocation code will check the secondary_free_list 3713 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3714 // set, skip this step so that the region allocation code has to 3715 // get entries from the secondary_free_list. 3716 if (!G1StressConcRegionFreeing) { 3717 append_secondary_free_list_if_not_empty_with_lock(); 3718 } 3719 3720 assert(check_young_list_well_formed(), "young list should be well formed"); 3721 3722 // Don't dynamically change the number of GC threads this early. A value of 3723 // 0 is used to indicate serial work. When parallel work is done, 3724 // it will be set. 3725 3726 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3727 IsGCActiveMark x; 3728 3729 gc_prologue(false); 3730 increment_total_collections(false /* full gc */); 3731 increment_gc_time_stamp(); 3732 3733 verify_before_gc(); 3734 3735 check_bitmaps("GC Start"); 3736 3737 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3738 3739 // Please see comment in g1CollectedHeap.hpp and 3740 // G1CollectedHeap::ref_processing_init() to see how 3741 // reference processing currently works in G1. 3742 3743 // Enable discovery in the STW reference processor 3744 ref_processor_stw()->enable_discovery(); 3745 3746 { 3747 // We want to temporarily turn off discovery by the 3748 // CM ref processor, if necessary, and turn it back on 3749 // on again later if we do. Using a scoped 3750 // NoRefDiscovery object will do this. 3751 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3752 3753 // Forget the current alloc region (we might even choose it to be part 3754 // of the collection set!). 3755 _allocator->release_mutator_alloc_region(); 3756 3757 // We should call this after we retire the mutator alloc 3758 // region(s) so that all the ALLOC / RETIRE events are generated 3759 // before the start GC event. 3760 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3761 3762 // This timing is only used by the ergonomics to handle our pause target. 3763 // It is unclear why this should not include the full pause. We will 3764 // investigate this in CR 7178365. 3765 // 3766 // Preserving the old comment here if that helps the investigation: 3767 // 3768 // The elapsed time induced by the start time below deliberately elides 3769 // the possible verification above. 3770 double sample_start_time_sec = os::elapsedTime(); 3771 3772 #if YOUNG_LIST_VERBOSE 3773 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 3774 _young_list->print(); 3775 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3776 #endif // YOUNG_LIST_VERBOSE 3777 3778 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3779 3780 double scan_wait_start = os::elapsedTime(); 3781 // We have to wait until the CM threads finish scanning the 3782 // root regions as it's the only way to ensure that all the 3783 // objects on them have been correctly scanned before we start 3784 // moving them during the GC. 3785 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3786 double wait_time_ms = 0.0; 3787 if (waited) { 3788 double scan_wait_end = os::elapsedTime(); 3789 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3790 } 3791 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3792 3793 #if YOUNG_LIST_VERBOSE 3794 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 3795 _young_list->print(); 3796 #endif // YOUNG_LIST_VERBOSE 3797 3798 if (g1_policy()->during_initial_mark_pause()) { 3799 concurrent_mark()->checkpointRootsInitialPre(); 3800 } 3801 3802 #if YOUNG_LIST_VERBOSE 3803 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 3804 _young_list->print(); 3805 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3806 #endif // YOUNG_LIST_VERBOSE 3807 3808 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 3809 3810 register_humongous_regions_with_cset(); 3811 3812 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3813 3814 _cm->note_start_of_gc(); 3815 // We call this after finalize_cset() to 3816 // ensure that the CSet has been finalized. 3817 _cm->verify_no_cset_oops(); 3818 3819 if (_hr_printer.is_active()) { 3820 HeapRegion* hr = g1_policy()->collection_set(); 3821 while (hr != NULL) { 3822 _hr_printer.cset(hr); 3823 hr = hr->next_in_collection_set(); 3824 } 3825 } 3826 3827 #ifdef ASSERT 3828 VerifyCSetClosure cl; 3829 collection_set_iterate(&cl); 3830 #endif // ASSERT 3831 3832 setup_surviving_young_words(); 3833 3834 // Initialize the GC alloc regions. 3835 _allocator->init_gc_alloc_regions(evacuation_info); 3836 3837 // Actually do the work... 3838 evacuate_collection_set(evacuation_info); 3839 3840 free_collection_set(g1_policy()->collection_set(), evacuation_info); 3841 3842 eagerly_reclaim_humongous_regions(); 3843 3844 g1_policy()->clear_collection_set(); 3845 3846 cleanup_surviving_young_words(); 3847 3848 // Start a new incremental collection set for the next pause. 3849 g1_policy()->start_incremental_cset_building(); 3850 3851 clear_cset_fast_test(); 3852 3853 _young_list->reset_sampled_info(); 3854 3855 // Don't check the whole heap at this point as the 3856 // GC alloc regions from this pause have been tagged 3857 // as survivors and moved on to the survivor list. 3858 // Survivor regions will fail the !is_young() check. 3859 assert(check_young_list_empty(false /* check_heap */), 3860 "young list should be empty"); 3861 3862 #if YOUNG_LIST_VERBOSE 3863 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 3864 _young_list->print(); 3865 #endif // YOUNG_LIST_VERBOSE 3866 3867 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 3868 _young_list->first_survivor_region(), 3869 _young_list->last_survivor_region()); 3870 3871 _young_list->reset_auxilary_lists(); 3872 3873 if (evacuation_failed()) { 3874 _allocator->set_used(recalculate_used()); 3875 uint n_queues = MAX2((int)ParallelGCThreads, 1); 3876 for (uint i = 0; i < n_queues; i++) { 3877 if (_evacuation_failed_info_array[i].has_failed()) { 3878 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3879 } 3880 } 3881 } else { 3882 // The "used" of the the collection set have already been subtracted 3883 // when they were freed. Add in the bytes evacuated. 3884 _allocator->increase_used(g1_policy()->bytes_copied_during_gc()); 3885 } 3886 3887 if (g1_policy()->during_initial_mark_pause()) { 3888 // We have to do this before we notify the CM threads that 3889 // they can start working to make sure that all the 3890 // appropriate initialization is done on the CM object. 3891 concurrent_mark()->checkpointRootsInitialPost(); 3892 set_marking_started(); 3893 // Note that we don't actually trigger the CM thread at 3894 // this point. We do that later when we're sure that 3895 // the current thread has completed its logging output. 3896 } 3897 3898 allocate_dummy_regions(); 3899 3900 #if YOUNG_LIST_VERBOSE 3901 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 3902 _young_list->print(); 3903 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3904 #endif // YOUNG_LIST_VERBOSE 3905 3906 _allocator->init_mutator_alloc_region(); 3907 3908 { 3909 size_t expand_bytes = g1_policy()->expansion_amount(); 3910 if (expand_bytes > 0) { 3911 size_t bytes_before = capacity(); 3912 // No need for an ergo verbose message here, 3913 // expansion_amount() does this when it returns a value > 0. 3914 if (!expand(expand_bytes)) { 3915 // We failed to expand the heap. Cannot do anything about it. 3916 } 3917 } 3918 } 3919 3920 // We redo the verification but now wrt to the new CSet which 3921 // has just got initialized after the previous CSet was freed. 3922 _cm->verify_no_cset_oops(); 3923 _cm->note_end_of_gc(); 3924 3925 // This timing is only used by the ergonomics to handle our pause target. 3926 // It is unclear why this should not include the full pause. We will 3927 // investigate this in CR 7178365. 3928 double sample_end_time_sec = os::elapsedTime(); 3929 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3930 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 3931 3932 MemoryService::track_memory_usage(); 3933 3934 // In prepare_for_verify() below we'll need to scan the deferred 3935 // update buffers to bring the RSets up-to-date if 3936 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 3937 // the update buffers we'll probably need to scan cards on the 3938 // regions we just allocated to (i.e., the GC alloc 3939 // regions). However, during the last GC we called 3940 // set_saved_mark() on all the GC alloc regions, so card 3941 // scanning might skip the [saved_mark_word()...top()] area of 3942 // those regions (i.e., the area we allocated objects into 3943 // during the last GC). But it shouldn't. Given that 3944 // saved_mark_word() is conditional on whether the GC time stamp 3945 // on the region is current or not, by incrementing the GC time 3946 // stamp here we invalidate all the GC time stamps on all the 3947 // regions and saved_mark_word() will simply return top() for 3948 // all the regions. This is a nicer way of ensuring this rather 3949 // than iterating over the regions and fixing them. In fact, the 3950 // GC time stamp increment here also ensures that 3951 // saved_mark_word() will return top() between pauses, i.e., 3952 // during concurrent refinement. So we don't need the 3953 // is_gc_active() check to decided which top to use when 3954 // scanning cards (see CR 7039627). 3955 increment_gc_time_stamp(); 3956 3957 verify_after_gc(); 3958 check_bitmaps("GC End"); 3959 3960 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 3961 ref_processor_stw()->verify_no_references_recorded(); 3962 3963 // CM reference discovery will be re-enabled if necessary. 3964 } 3965 3966 // We should do this after we potentially expand the heap so 3967 // that all the COMMIT events are generated before the end GC 3968 // event, and after we retire the GC alloc regions so that all 3969 // RETIRE events are generated before the end GC event. 3970 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 3971 3972 #ifdef TRACESPINNING 3973 ParallelTaskTerminator::print_termination_counts(); 3974 #endif 3975 3976 gc_epilogue(false); 3977 } 3978 3979 // Print the remainder of the GC log output. 3980 log_gc_footer(os::elapsedTime() - pause_start_sec); 3981 3982 // It is not yet to safe to tell the concurrent mark to 3983 // start as we have some optional output below. We don't want the 3984 // output from the concurrent mark thread interfering with this 3985 // logging output either. 3986 3987 _hrm.verify_optional(); 3988 verify_region_sets_optional(); 3989 3990 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats()); 3991 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3992 3993 print_heap_after_gc(); 3994 trace_heap_after_gc(_gc_tracer_stw); 3995 3996 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3997 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3998 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3999 // before any GC notifications are raised. 4000 g1mm()->update_sizes(); 4001 4002 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4003 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4004 _gc_timer_stw->register_gc_end(); 4005 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4006 } 4007 // It should now be safe to tell the concurrent mark thread to start 4008 // without its logging output interfering with the logging output 4009 // that came from the pause. 4010 4011 if (should_start_conc_mark) { 4012 // CAUTION: after the doConcurrentMark() call below, 4013 // the concurrent marking thread(s) could be running 4014 // concurrently with us. Make sure that anything after 4015 // this point does not assume that we are the only GC thread 4016 // running. Note: of course, the actual marking work will 4017 // not start until the safepoint itself is released in 4018 // SuspendibleThreadSet::desynchronize(). 4019 doConcurrentMark(); 4020 } 4021 4022 return true; 4023 } 4024 4025 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4026 _drain_in_progress = false; 4027 set_evac_failure_closure(cl); 4028 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4029 } 4030 4031 void G1CollectedHeap::finalize_for_evac_failure() { 4032 assert(_evac_failure_scan_stack != NULL && 4033 _evac_failure_scan_stack->length() == 0, 4034 "Postcondition"); 4035 assert(!_drain_in_progress, "Postcondition"); 4036 delete _evac_failure_scan_stack; 4037 _evac_failure_scan_stack = NULL; 4038 } 4039 4040 void G1CollectedHeap::remove_self_forwarding_pointers() { 4041 double remove_self_forwards_start = os::elapsedTime(); 4042 4043 set_par_threads(); 4044 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4045 workers()->run_task(&rsfp_task); 4046 set_par_threads(0); 4047 4048 // Now restore saved marks, if any. 4049 assert(_objs_with_preserved_marks.size() == 4050 _preserved_marks_of_objs.size(), "Both or none."); 4051 while (!_objs_with_preserved_marks.is_empty()) { 4052 oop obj = _objs_with_preserved_marks.pop(); 4053 markOop m = _preserved_marks_of_objs.pop(); 4054 obj->set_mark(m); 4055 } 4056 _objs_with_preserved_marks.clear(true); 4057 _preserved_marks_of_objs.clear(true); 4058 4059 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4060 } 4061 4062 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4063 _evac_failure_scan_stack->push(obj); 4064 } 4065 4066 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4067 assert(_evac_failure_scan_stack != NULL, "precondition"); 4068 4069 while (_evac_failure_scan_stack->length() > 0) { 4070 oop obj = _evac_failure_scan_stack->pop(); 4071 _evac_failure_closure->set_region(heap_region_containing(obj)); 4072 obj->oop_iterate_backwards(_evac_failure_closure); 4073 } 4074 } 4075 4076 oop 4077 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4078 oop old) { 4079 assert(obj_in_cs(old), 4080 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4081 p2i(old))); 4082 markOop m = old->mark(); 4083 oop forward_ptr = old->forward_to_atomic(old); 4084 if (forward_ptr == NULL) { 4085 // Forward-to-self succeeded. 4086 assert(_par_scan_state != NULL, "par scan state"); 4087 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4088 uint queue_num = _par_scan_state->queue_num(); 4089 4090 _evacuation_failed = true; 4091 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4092 if (_evac_failure_closure != cl) { 4093 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4094 assert(!_drain_in_progress, 4095 "Should only be true while someone holds the lock."); 4096 // Set the global evac-failure closure to the current thread's. 4097 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4098 set_evac_failure_closure(cl); 4099 // Now do the common part. 4100 handle_evacuation_failure_common(old, m); 4101 // Reset to NULL. 4102 set_evac_failure_closure(NULL); 4103 } else { 4104 // The lock is already held, and this is recursive. 4105 assert(_drain_in_progress, "This should only be the recursive case."); 4106 handle_evacuation_failure_common(old, m); 4107 } 4108 return old; 4109 } else { 4110 // Forward-to-self failed. Either someone else managed to allocate 4111 // space for this object (old != forward_ptr) or they beat us in 4112 // self-forwarding it (old == forward_ptr). 4113 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4114 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4115 "should not be in the CSet", 4116 p2i(old), p2i(forward_ptr))); 4117 return forward_ptr; 4118 } 4119 } 4120 4121 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4122 preserve_mark_if_necessary(old, m); 4123 4124 HeapRegion* r = heap_region_containing(old); 4125 if (!r->evacuation_failed()) { 4126 r->set_evacuation_failed(true); 4127 _hr_printer.evac_failure(r); 4128 } 4129 4130 push_on_evac_failure_scan_stack(old); 4131 4132 if (!_drain_in_progress) { 4133 // prevent recursion in copy_to_survivor_space() 4134 _drain_in_progress = true; 4135 drain_evac_failure_scan_stack(); 4136 _drain_in_progress = false; 4137 } 4138 } 4139 4140 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4141 assert(evacuation_failed(), "Oversaving!"); 4142 // We want to call the "for_promotion_failure" version only in the 4143 // case of a promotion failure. 4144 if (m->must_be_preserved_for_promotion_failure(obj)) { 4145 _objs_with_preserved_marks.push(obj); 4146 _preserved_marks_of_objs.push(m); 4147 } 4148 } 4149 4150 void G1ParCopyHelper::mark_object(oop obj) { 4151 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); 4152 4153 // We know that the object is not moving so it's safe to read its size. 4154 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4155 } 4156 4157 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4158 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4159 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4160 assert(from_obj != to_obj, "should not be self-forwarded"); 4161 4162 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); 4163 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); 4164 4165 // The object might be in the process of being copied by another 4166 // worker so we cannot trust that its to-space image is 4167 // well-formed. So we have to read its size from its from-space 4168 // image which we know should not be changing. 4169 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4170 } 4171 4172 template <class T> 4173 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4174 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4175 _scanned_klass->record_modified_oops(); 4176 } 4177 } 4178 4179 template <G1Barrier barrier, G1Mark do_mark_object> 4180 template <class T> 4181 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4182 T heap_oop = oopDesc::load_heap_oop(p); 4183 4184 if (oopDesc::is_null(heap_oop)) { 4185 return; 4186 } 4187 4188 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4189 4190 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4191 4192 const InCSetState state = _g1->in_cset_state(obj); 4193 if (state.is_in_cset()) { 4194 oop forwardee; 4195 markOop m = obj->mark(); 4196 if (m->is_marked()) { 4197 forwardee = (oop) m->decode_pointer(); 4198 } else { 4199 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m); 4200 } 4201 assert(forwardee != NULL, "forwardee should not be NULL"); 4202 oopDesc::encode_store_heap_oop(p, forwardee); 4203 if (do_mark_object != G1MarkNone && forwardee != obj) { 4204 // If the object is self-forwarded we don't need to explicitly 4205 // mark it, the evacuation failure protocol will do so. 4206 mark_forwarded_object(obj, forwardee); 4207 } 4208 4209 if (barrier == G1BarrierKlass) { 4210 do_klass_barrier(p, forwardee); 4211 } 4212 } else { 4213 if (state.is_humongous()) { 4214 _g1->set_humongous_is_live(obj); 4215 } 4216 // The object is not in collection set. If we're a root scanning 4217 // closure during an initial mark pause then attempt to mark the object. 4218 if (do_mark_object == G1MarkFromRoot) { 4219 mark_object(obj); 4220 } 4221 } 4222 4223 if (barrier == G1BarrierEvac) { 4224 _par_scan_state->update_rs(_from, p, _worker_id); 4225 } 4226 } 4227 4228 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p); 4229 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p); 4230 4231 class G1ParEvacuateFollowersClosure : public VoidClosure { 4232 protected: 4233 G1CollectedHeap* _g1h; 4234 G1ParScanThreadState* _par_scan_state; 4235 RefToScanQueueSet* _queues; 4236 ParallelTaskTerminator* _terminator; 4237 4238 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4239 RefToScanQueueSet* queues() { return _queues; } 4240 ParallelTaskTerminator* terminator() { return _terminator; } 4241 4242 public: 4243 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4244 G1ParScanThreadState* par_scan_state, 4245 RefToScanQueueSet* queues, 4246 ParallelTaskTerminator* terminator) 4247 : _g1h(g1h), _par_scan_state(par_scan_state), 4248 _queues(queues), _terminator(terminator) {} 4249 4250 void do_void(); 4251 4252 private: 4253 inline bool offer_termination(); 4254 }; 4255 4256 bool G1ParEvacuateFollowersClosure::offer_termination() { 4257 G1ParScanThreadState* const pss = par_scan_state(); 4258 pss->start_term_time(); 4259 const bool res = terminator()->offer_termination(); 4260 pss->end_term_time(); 4261 return res; 4262 } 4263 4264 void G1ParEvacuateFollowersClosure::do_void() { 4265 G1ParScanThreadState* const pss = par_scan_state(); 4266 pss->trim_queue(); 4267 do { 4268 pss->steal_and_trim_queue(queues()); 4269 } while (!offer_termination()); 4270 } 4271 4272 class G1KlassScanClosure : public KlassClosure { 4273 G1ParCopyHelper* _closure; 4274 bool _process_only_dirty; 4275 int _count; 4276 public: 4277 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4278 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4279 void do_klass(Klass* klass) { 4280 // If the klass has not been dirtied we know that there's 4281 // no references into the young gen and we can skip it. 4282 if (!_process_only_dirty || klass->has_modified_oops()) { 4283 // Clean the klass since we're going to scavenge all the metadata. 4284 klass->clear_modified_oops(); 4285 4286 // Tell the closure that this klass is the Klass to scavenge 4287 // and is the one to dirty if oops are left pointing into the young gen. 4288 _closure->set_scanned_klass(klass); 4289 4290 klass->oops_do(_closure); 4291 4292 _closure->set_scanned_klass(NULL); 4293 } 4294 _count++; 4295 } 4296 }; 4297 4298 class G1ParTask : public AbstractGangTask { 4299 protected: 4300 G1CollectedHeap* _g1h; 4301 RefToScanQueueSet *_queues; 4302 G1RootProcessor* _root_processor; 4303 ParallelTaskTerminator _terminator; 4304 uint _n_workers; 4305 4306 Mutex _stats_lock; 4307 Mutex* stats_lock() { return &_stats_lock; } 4308 4309 public: 4310 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor) 4311 : AbstractGangTask("G1 collection"), 4312 _g1h(g1h), 4313 _queues(task_queues), 4314 _root_processor(root_processor), 4315 _terminator(0, _queues), 4316 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4317 {} 4318 4319 RefToScanQueueSet* queues() { return _queues; } 4320 4321 RefToScanQueue *work_queue(int i) { 4322 return queues()->queue(i); 4323 } 4324 4325 ParallelTaskTerminator* terminator() { return &_terminator; } 4326 4327 virtual void set_for_termination(uint active_workers) { 4328 _root_processor->set_num_workers(active_workers); 4329 terminator()->reset_for_reuse(active_workers); 4330 _n_workers = active_workers; 4331 } 4332 4333 // Helps out with CLD processing. 4334 // 4335 // During InitialMark we need to: 4336 // 1) Scavenge all CLDs for the young GC. 4337 // 2) Mark all objects directly reachable from strong CLDs. 4338 template <G1Mark do_mark_object> 4339 class G1CLDClosure : public CLDClosure { 4340 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure; 4341 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure; 4342 G1KlassScanClosure _klass_in_cld_closure; 4343 bool _claim; 4344 4345 public: 4346 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure, 4347 bool only_young, bool claim) 4348 : _oop_closure(oop_closure), 4349 _oop_in_klass_closure(oop_closure->g1(), 4350 oop_closure->pss(), 4351 oop_closure->rp()), 4352 _klass_in_cld_closure(&_oop_in_klass_closure, only_young), 4353 _claim(claim) { 4354 4355 } 4356 4357 void do_cld(ClassLoaderData* cld) { 4358 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim); 4359 } 4360 }; 4361 4362 void work(uint worker_id) { 4363 if (worker_id >= _n_workers) return; // no work needed this round 4364 4365 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime()); 4366 4367 { 4368 ResourceMark rm; 4369 HandleMark hm; 4370 4371 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4372 4373 G1ParScanThreadState pss(_g1h, worker_id, rp); 4374 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 4375 4376 pss.set_evac_failure_closure(&evac_failure_cl); 4377 4378 bool only_young = _g1h->g1_policy()->gcs_are_young(); 4379 4380 // Non-IM young GC. 4381 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp); 4382 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl, 4383 only_young, // Only process dirty klasses. 4384 false); // No need to claim CLDs. 4385 // IM young GC. 4386 // Strong roots closures. 4387 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp); 4388 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl, 4389 false, // Process all klasses. 4390 true); // Need to claim CLDs. 4391 // Weak roots closures. 4392 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp); 4393 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl, 4394 false, // Process all klasses. 4395 true); // Need to claim CLDs. 4396 4397 OopClosure* strong_root_cl; 4398 OopClosure* weak_root_cl; 4399 CLDClosure* strong_cld_cl; 4400 CLDClosure* weak_cld_cl; 4401 4402 bool trace_metadata = false; 4403 4404 if (_g1h->g1_policy()->during_initial_mark_pause()) { 4405 // We also need to mark copied objects. 4406 strong_root_cl = &scan_mark_root_cl; 4407 strong_cld_cl = &scan_mark_cld_cl; 4408 if (ClassUnloadingWithConcurrentMark) { 4409 weak_root_cl = &scan_mark_weak_root_cl; 4410 weak_cld_cl = &scan_mark_weak_cld_cl; 4411 trace_metadata = true; 4412 } else { 4413 weak_root_cl = &scan_mark_root_cl; 4414 weak_cld_cl = &scan_mark_cld_cl; 4415 } 4416 } else { 4417 strong_root_cl = &scan_only_root_cl; 4418 weak_root_cl = &scan_only_root_cl; 4419 strong_cld_cl = &scan_only_cld_cl; 4420 weak_cld_cl = &scan_only_cld_cl; 4421 } 4422 4423 pss.start_strong_roots(); 4424 4425 _root_processor->evacuate_roots(strong_root_cl, 4426 weak_root_cl, 4427 strong_cld_cl, 4428 weak_cld_cl, 4429 trace_metadata, 4430 worker_id); 4431 4432 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4433 _root_processor->scan_remembered_sets(&push_heap_rs_cl, 4434 weak_root_cl, 4435 worker_id); 4436 pss.end_strong_roots(); 4437 4438 { 4439 double start = os::elapsedTime(); 4440 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4441 evac.do_void(); 4442 double elapsed_sec = os::elapsedTime() - start; 4443 double term_sec = pss.term_time(); 4444 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 4445 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 4446 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts()); 4447 } 4448 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4449 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4450 4451 if (PrintTerminationStats) { 4452 MutexLocker x(stats_lock()); 4453 pss.print_termination_stats(worker_id); 4454 } 4455 4456 assert(pss.queue_is_empty(), "should be empty"); 4457 4458 // Close the inner scope so that the ResourceMark and HandleMark 4459 // destructors are executed here and are included as part of the 4460 // "GC Worker Time". 4461 } 4462 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 4463 } 4464 }; 4465 4466 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4467 private: 4468 BoolObjectClosure* _is_alive; 4469 int _initial_string_table_size; 4470 int _initial_symbol_table_size; 4471 4472 bool _process_strings; 4473 int _strings_processed; 4474 int _strings_removed; 4475 4476 bool _process_symbols; 4477 int _symbols_processed; 4478 int _symbols_removed; 4479 4480 public: 4481 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4482 AbstractGangTask("String/Symbol Unlinking"), 4483 _is_alive(is_alive), 4484 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4485 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4486 4487 _initial_string_table_size = StringTable::the_table()->table_size(); 4488 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4489 if (process_strings) { 4490 StringTable::clear_parallel_claimed_index(); 4491 } 4492 if (process_symbols) { 4493 SymbolTable::clear_parallel_claimed_index(); 4494 } 4495 } 4496 4497 ~G1StringSymbolTableUnlinkTask() { 4498 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4499 err_msg("claim value %d after unlink less than initial string table size %d", 4500 StringTable::parallel_claimed_index(), _initial_string_table_size)); 4501 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4502 err_msg("claim value %d after unlink less than initial symbol table size %d", 4503 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 4504 4505 if (G1TraceStringSymbolTableScrubbing) { 4506 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4507 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 4508 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 4509 strings_processed(), strings_removed(), 4510 symbols_processed(), symbols_removed()); 4511 } 4512 } 4513 4514 void work(uint worker_id) { 4515 int strings_processed = 0; 4516 int strings_removed = 0; 4517 int symbols_processed = 0; 4518 int symbols_removed = 0; 4519 if (_process_strings) { 4520 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4521 Atomic::add(strings_processed, &_strings_processed); 4522 Atomic::add(strings_removed, &_strings_removed); 4523 } 4524 if (_process_symbols) { 4525 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 4526 Atomic::add(symbols_processed, &_symbols_processed); 4527 Atomic::add(symbols_removed, &_symbols_removed); 4528 } 4529 } 4530 4531 size_t strings_processed() const { return (size_t)_strings_processed; } 4532 size_t strings_removed() const { return (size_t)_strings_removed; } 4533 4534 size_t symbols_processed() const { return (size_t)_symbols_processed; } 4535 size_t symbols_removed() const { return (size_t)_symbols_removed; } 4536 }; 4537 4538 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 4539 private: 4540 static Monitor* _lock; 4541 4542 BoolObjectClosure* const _is_alive; 4543 const bool _unloading_occurred; 4544 const uint _num_workers; 4545 4546 // Variables used to claim nmethods. 4547 nmethod* _first_nmethod; 4548 volatile nmethod* _claimed_nmethod; 4549 4550 // The list of nmethods that need to be processed by the second pass. 4551 volatile nmethod* _postponed_list; 4552 volatile uint _num_entered_barrier; 4553 4554 public: 4555 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 4556 _is_alive(is_alive), 4557 _unloading_occurred(unloading_occurred), 4558 _num_workers(num_workers), 4559 _first_nmethod(NULL), 4560 _claimed_nmethod(NULL), 4561 _postponed_list(NULL), 4562 _num_entered_barrier(0) 4563 { 4564 nmethod::increase_unloading_clock(); 4565 // Get first alive nmethod 4566 NMethodIterator iter = NMethodIterator(); 4567 if(iter.next_alive()) { 4568 _first_nmethod = iter.method(); 4569 } 4570 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 4571 } 4572 4573 ~G1CodeCacheUnloadingTask() { 4574 CodeCache::verify_clean_inline_caches(); 4575 4576 CodeCache::set_needs_cache_clean(false); 4577 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 4578 4579 CodeCache::verify_icholder_relocations(); 4580 } 4581 4582 private: 4583 void add_to_postponed_list(nmethod* nm) { 4584 nmethod* old; 4585 do { 4586 old = (nmethod*)_postponed_list; 4587 nm->set_unloading_next(old); 4588 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 4589 } 4590 4591 void clean_nmethod(nmethod* nm) { 4592 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 4593 4594 if (postponed) { 4595 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 4596 add_to_postponed_list(nm); 4597 } 4598 4599 // Mark that this thread has been cleaned/unloaded. 4600 // After this call, it will be safe to ask if this nmethod was unloaded or not. 4601 nm->set_unloading_clock(nmethod::global_unloading_clock()); 4602 } 4603 4604 void clean_nmethod_postponed(nmethod* nm) { 4605 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 4606 } 4607 4608 static const int MaxClaimNmethods = 16; 4609 4610 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 4611 nmethod* first; 4612 NMethodIterator last; 4613 4614 do { 4615 *num_claimed_nmethods = 0; 4616 4617 first = (nmethod*)_claimed_nmethod; 4618 last = NMethodIterator(first); 4619 4620 if (first != NULL) { 4621 4622 for (int i = 0; i < MaxClaimNmethods; i++) { 4623 if (!last.next_alive()) { 4624 break; 4625 } 4626 claimed_nmethods[i] = last.method(); 4627 (*num_claimed_nmethods)++; 4628 } 4629 } 4630 4631 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 4632 } 4633 4634 nmethod* claim_postponed_nmethod() { 4635 nmethod* claim; 4636 nmethod* next; 4637 4638 do { 4639 claim = (nmethod*)_postponed_list; 4640 if (claim == NULL) { 4641 return NULL; 4642 } 4643 4644 next = claim->unloading_next(); 4645 4646 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 4647 4648 return claim; 4649 } 4650 4651 public: 4652 // Mark that we're done with the first pass of nmethod cleaning. 4653 void barrier_mark(uint worker_id) { 4654 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4655 _num_entered_barrier++; 4656 if (_num_entered_barrier == _num_workers) { 4657 ml.notify_all(); 4658 } 4659 } 4660 4661 // See if we have to wait for the other workers to 4662 // finish their first-pass nmethod cleaning work. 4663 void barrier_wait(uint worker_id) { 4664 if (_num_entered_barrier < _num_workers) { 4665 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4666 while (_num_entered_barrier < _num_workers) { 4667 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 4668 } 4669 } 4670 } 4671 4672 // Cleaning and unloading of nmethods. Some work has to be postponed 4673 // to the second pass, when we know which nmethods survive. 4674 void work_first_pass(uint worker_id) { 4675 // The first nmethods is claimed by the first worker. 4676 if (worker_id == 0 && _first_nmethod != NULL) { 4677 clean_nmethod(_first_nmethod); 4678 _first_nmethod = NULL; 4679 } 4680 4681 int num_claimed_nmethods; 4682 nmethod* claimed_nmethods[MaxClaimNmethods]; 4683 4684 while (true) { 4685 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 4686 4687 if (num_claimed_nmethods == 0) { 4688 break; 4689 } 4690 4691 for (int i = 0; i < num_claimed_nmethods; i++) { 4692 clean_nmethod(claimed_nmethods[i]); 4693 } 4694 } 4695 } 4696 4697 void work_second_pass(uint worker_id) { 4698 nmethod* nm; 4699 // Take care of postponed nmethods. 4700 while ((nm = claim_postponed_nmethod()) != NULL) { 4701 clean_nmethod_postponed(nm); 4702 } 4703 } 4704 }; 4705 4706 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 4707 4708 class G1KlassCleaningTask : public StackObj { 4709 BoolObjectClosure* _is_alive; 4710 volatile jint _clean_klass_tree_claimed; 4711 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 4712 4713 public: 4714 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 4715 _is_alive(is_alive), 4716 _clean_klass_tree_claimed(0), 4717 _klass_iterator() { 4718 } 4719 4720 private: 4721 bool claim_clean_klass_tree_task() { 4722 if (_clean_klass_tree_claimed) { 4723 return false; 4724 } 4725 4726 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 4727 } 4728 4729 InstanceKlass* claim_next_klass() { 4730 Klass* klass; 4731 do { 4732 klass =_klass_iterator.next_klass(); 4733 } while (klass != NULL && !klass->oop_is_instance()); 4734 4735 return (InstanceKlass*)klass; 4736 } 4737 4738 public: 4739 4740 void clean_klass(InstanceKlass* ik) { 4741 ik->clean_implementors_list(_is_alive); 4742 ik->clean_method_data(_is_alive); 4743 4744 // G1 specific cleanup work that has 4745 // been moved here to be done in parallel. 4746 ik->clean_dependent_nmethods(); 4747 } 4748 4749 void work() { 4750 ResourceMark rm; 4751 4752 // One worker will clean the subklass/sibling klass tree. 4753 if (claim_clean_klass_tree_task()) { 4754 Klass::clean_subklass_tree(_is_alive); 4755 } 4756 4757 // All workers will help cleaning the classes, 4758 InstanceKlass* klass; 4759 while ((klass = claim_next_klass()) != NULL) { 4760 clean_klass(klass); 4761 } 4762 } 4763 }; 4764 4765 // To minimize the remark pause times, the tasks below are done in parallel. 4766 class G1ParallelCleaningTask : public AbstractGangTask { 4767 private: 4768 G1StringSymbolTableUnlinkTask _string_symbol_task; 4769 G1CodeCacheUnloadingTask _code_cache_task; 4770 G1KlassCleaningTask _klass_cleaning_task; 4771 4772 public: 4773 // The constructor is run in the VMThread. 4774 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 4775 AbstractGangTask("Parallel Cleaning"), 4776 _string_symbol_task(is_alive, process_strings, process_symbols), 4777 _code_cache_task(num_workers, is_alive, unloading_occurred), 4778 _klass_cleaning_task(is_alive) { 4779 } 4780 4781 // The parallel work done by all worker threads. 4782 void work(uint worker_id) { 4783 // Do first pass of code cache cleaning. 4784 _code_cache_task.work_first_pass(worker_id); 4785 4786 // Let the threads mark that the first pass is done. 4787 _code_cache_task.barrier_mark(worker_id); 4788 4789 // Clean the Strings and Symbols. 4790 _string_symbol_task.work(worker_id); 4791 4792 // Wait for all workers to finish the first code cache cleaning pass. 4793 _code_cache_task.barrier_wait(worker_id); 4794 4795 // Do the second code cache cleaning work, which realize on 4796 // the liveness information gathered during the first pass. 4797 _code_cache_task.work_second_pass(worker_id); 4798 4799 // Clean all klasses that were not unloaded. 4800 _klass_cleaning_task.work(); 4801 } 4802 }; 4803 4804 4805 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 4806 bool process_strings, 4807 bool process_symbols, 4808 bool class_unloading_occurred) { 4809 uint n_workers = workers()->active_workers(); 4810 4811 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 4812 n_workers, class_unloading_occurred); 4813 set_par_threads(n_workers); 4814 workers()->run_task(&g1_unlink_task); 4815 set_par_threads(0); 4816 } 4817 4818 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 4819 bool process_strings, bool process_symbols) { 4820 { 4821 uint n_workers = workers()->active_workers(); 4822 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 4823 set_par_threads(n_workers); 4824 workers()->run_task(&g1_unlink_task); 4825 set_par_threads(0); 4826 } 4827 4828 if (G1StringDedup::is_enabled()) { 4829 G1StringDedup::unlink(is_alive); 4830 } 4831 } 4832 4833 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 4834 private: 4835 DirtyCardQueueSet* _queue; 4836 public: 4837 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 4838 4839 virtual void work(uint worker_id) { 4840 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4841 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 4842 4843 RedirtyLoggedCardTableEntryClosure cl; 4844 _queue->par_apply_closure_to_all_completed_buffers(&cl); 4845 4846 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed()); 4847 } 4848 }; 4849 4850 void G1CollectedHeap::redirty_logged_cards() { 4851 double redirty_logged_cards_start = os::elapsedTime(); 4852 4853 uint n_workers = workers()->active_workers(); 4854 4855 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 4856 dirty_card_queue_set().reset_for_par_iteration(); 4857 set_par_threads(n_workers); 4858 workers()->run_task(&redirty_task); 4859 set_par_threads(0); 4860 4861 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 4862 dcq.merge_bufferlists(&dirty_card_queue_set()); 4863 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 4864 4865 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 4866 } 4867 4868 // Weak Reference Processing support 4869 4870 // An always "is_alive" closure that is used to preserve referents. 4871 // If the object is non-null then it's alive. Used in the preservation 4872 // of referent objects that are pointed to by reference objects 4873 // discovered by the CM ref processor. 4874 class G1AlwaysAliveClosure: public BoolObjectClosure { 4875 G1CollectedHeap* _g1; 4876 public: 4877 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4878 bool do_object_b(oop p) { 4879 if (p != NULL) { 4880 return true; 4881 } 4882 return false; 4883 } 4884 }; 4885 4886 bool G1STWIsAliveClosure::do_object_b(oop p) { 4887 // An object is reachable if it is outside the collection set, 4888 // or is inside and copied. 4889 return !_g1->obj_in_cs(p) || p->is_forwarded(); 4890 } 4891 4892 // Non Copying Keep Alive closure 4893 class G1KeepAliveClosure: public OopClosure { 4894 G1CollectedHeap* _g1; 4895 public: 4896 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 4897 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 4898 void do_oop(oop* p) { 4899 oop obj = *p; 4900 assert(obj != NULL, "the caller should have filtered out NULL values"); 4901 4902 const InCSetState cset_state = _g1->in_cset_state(obj); 4903 if (!cset_state.is_in_cset_or_humongous()) { 4904 return; 4905 } 4906 if (cset_state.is_in_cset()) { 4907 assert( obj->is_forwarded(), "invariant" ); 4908 *p = obj->forwardee(); 4909 } else { 4910 assert(!obj->is_forwarded(), "invariant" ); 4911 assert(cset_state.is_humongous(), 4912 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value())); 4913 _g1->set_humongous_is_live(obj); 4914 } 4915 } 4916 }; 4917 4918 // Copying Keep Alive closure - can be called from both 4919 // serial and parallel code as long as different worker 4920 // threads utilize different G1ParScanThreadState instances 4921 // and different queues. 4922 4923 class G1CopyingKeepAliveClosure: public OopClosure { 4924 G1CollectedHeap* _g1h; 4925 OopClosure* _copy_non_heap_obj_cl; 4926 G1ParScanThreadState* _par_scan_state; 4927 4928 public: 4929 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 4930 OopClosure* non_heap_obj_cl, 4931 G1ParScanThreadState* pss): 4932 _g1h(g1h), 4933 _copy_non_heap_obj_cl(non_heap_obj_cl), 4934 _par_scan_state(pss) 4935 {} 4936 4937 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 4938 virtual void do_oop( oop* p) { do_oop_work(p); } 4939 4940 template <class T> void do_oop_work(T* p) { 4941 oop obj = oopDesc::load_decode_heap_oop(p); 4942 4943 if (_g1h->is_in_cset_or_humongous(obj)) { 4944 // If the referent object has been forwarded (either copied 4945 // to a new location or to itself in the event of an 4946 // evacuation failure) then we need to update the reference 4947 // field and, if both reference and referent are in the G1 4948 // heap, update the RSet for the referent. 4949 // 4950 // If the referent has not been forwarded then we have to keep 4951 // it alive by policy. Therefore we have copy the referent. 4952 // 4953 // If the reference field is in the G1 heap then we can push 4954 // on the PSS queue. When the queue is drained (after each 4955 // phase of reference processing) the object and it's followers 4956 // will be copied, the reference field set to point to the 4957 // new location, and the RSet updated. Otherwise we need to 4958 // use the the non-heap or metadata closures directly to copy 4959 // the referent object and update the pointer, while avoiding 4960 // updating the RSet. 4961 4962 if (_g1h->is_in_g1_reserved(p)) { 4963 _par_scan_state->push_on_queue(p); 4964 } else { 4965 assert(!Metaspace::contains((const void*)p), 4966 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p))); 4967 _copy_non_heap_obj_cl->do_oop(p); 4968 } 4969 } 4970 } 4971 }; 4972 4973 // Serial drain queue closure. Called as the 'complete_gc' 4974 // closure for each discovered list in some of the 4975 // reference processing phases. 4976 4977 class G1STWDrainQueueClosure: public VoidClosure { 4978 protected: 4979 G1CollectedHeap* _g1h; 4980 G1ParScanThreadState* _par_scan_state; 4981 4982 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4983 4984 public: 4985 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 4986 _g1h(g1h), 4987 _par_scan_state(pss) 4988 { } 4989 4990 void do_void() { 4991 G1ParScanThreadState* const pss = par_scan_state(); 4992 pss->trim_queue(); 4993 } 4994 }; 4995 4996 // Parallel Reference Processing closures 4997 4998 // Implementation of AbstractRefProcTaskExecutor for parallel reference 4999 // processing during G1 evacuation pauses. 5000 5001 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5002 private: 5003 G1CollectedHeap* _g1h; 5004 RefToScanQueueSet* _queues; 5005 FlexibleWorkGang* _workers; 5006 uint _active_workers; 5007 5008 public: 5009 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5010 FlexibleWorkGang* workers, 5011 RefToScanQueueSet *task_queues, 5012 uint n_workers) : 5013 _g1h(g1h), 5014 _queues(task_queues), 5015 _workers(workers), 5016 _active_workers(n_workers) 5017 { 5018 assert(n_workers > 0, "shouldn't call this otherwise"); 5019 } 5020 5021 // Executes the given task using concurrent marking worker threads. 5022 virtual void execute(ProcessTask& task); 5023 virtual void execute(EnqueueTask& task); 5024 }; 5025 5026 // Gang task for possibly parallel reference processing 5027 5028 class G1STWRefProcTaskProxy: public AbstractGangTask { 5029 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5030 ProcessTask& _proc_task; 5031 G1CollectedHeap* _g1h; 5032 RefToScanQueueSet *_task_queues; 5033 ParallelTaskTerminator* _terminator; 5034 5035 public: 5036 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5037 G1CollectedHeap* g1h, 5038 RefToScanQueueSet *task_queues, 5039 ParallelTaskTerminator* terminator) : 5040 AbstractGangTask("Process reference objects in parallel"), 5041 _proc_task(proc_task), 5042 _g1h(g1h), 5043 _task_queues(task_queues), 5044 _terminator(terminator) 5045 {} 5046 5047 virtual void work(uint worker_id) { 5048 // The reference processing task executed by a single worker. 5049 ResourceMark rm; 5050 HandleMark hm; 5051 5052 G1STWIsAliveClosure is_alive(_g1h); 5053 5054 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5055 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5056 5057 pss.set_evac_failure_closure(&evac_failure_cl); 5058 5059 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5060 5061 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5062 5063 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5064 5065 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5066 // We also need to mark copied objects. 5067 copy_non_heap_cl = ©_mark_non_heap_cl; 5068 } 5069 5070 // Keep alive closure. 5071 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5072 5073 // Complete GC closure 5074 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5075 5076 // Call the reference processing task's work routine. 5077 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5078 5079 // Note we cannot assert that the refs array is empty here as not all 5080 // of the processing tasks (specifically phase2 - pp2_work) execute 5081 // the complete_gc closure (which ordinarily would drain the queue) so 5082 // the queue may not be empty. 5083 } 5084 }; 5085 5086 // Driver routine for parallel reference processing. 5087 // Creates an instance of the ref processing gang 5088 // task and has the worker threads execute it. 5089 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5090 assert(_workers != NULL, "Need parallel worker threads."); 5091 5092 ParallelTaskTerminator terminator(_active_workers, _queues); 5093 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5094 5095 _g1h->set_par_threads(_active_workers); 5096 _workers->run_task(&proc_task_proxy); 5097 _g1h->set_par_threads(0); 5098 } 5099 5100 // Gang task for parallel reference enqueueing. 5101 5102 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5103 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5104 EnqueueTask& _enq_task; 5105 5106 public: 5107 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5108 AbstractGangTask("Enqueue reference objects in parallel"), 5109 _enq_task(enq_task) 5110 { } 5111 5112 virtual void work(uint worker_id) { 5113 _enq_task.work(worker_id); 5114 } 5115 }; 5116 5117 // Driver routine for parallel reference enqueueing. 5118 // Creates an instance of the ref enqueueing gang 5119 // task and has the worker threads execute it. 5120 5121 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5122 assert(_workers != NULL, "Need parallel worker threads."); 5123 5124 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5125 5126 _g1h->set_par_threads(_active_workers); 5127 _workers->run_task(&enq_task_proxy); 5128 _g1h->set_par_threads(0); 5129 } 5130 5131 // End of weak reference support closures 5132 5133 // Abstract task used to preserve (i.e. copy) any referent objects 5134 // that are in the collection set and are pointed to by reference 5135 // objects discovered by the CM ref processor. 5136 5137 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5138 protected: 5139 G1CollectedHeap* _g1h; 5140 RefToScanQueueSet *_queues; 5141 ParallelTaskTerminator _terminator; 5142 uint _n_workers; 5143 5144 public: 5145 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, uint workers, RefToScanQueueSet *task_queues) : 5146 AbstractGangTask("ParPreserveCMReferents"), 5147 _g1h(g1h), 5148 _queues(task_queues), 5149 _terminator(workers, _queues), 5150 _n_workers(workers) 5151 { } 5152 5153 void work(uint worker_id) { 5154 ResourceMark rm; 5155 HandleMark hm; 5156 5157 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5158 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5159 5160 pss.set_evac_failure_closure(&evac_failure_cl); 5161 5162 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5163 5164 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5165 5166 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5167 5168 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5169 5170 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5171 // We also need to mark copied objects. 5172 copy_non_heap_cl = ©_mark_non_heap_cl; 5173 } 5174 5175 // Is alive closure 5176 G1AlwaysAliveClosure always_alive(_g1h); 5177 5178 // Copying keep alive closure. Applied to referent objects that need 5179 // to be copied. 5180 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5181 5182 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5183 5184 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5185 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5186 5187 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5188 // So this must be true - but assert just in case someone decides to 5189 // change the worker ids. 5190 assert(worker_id < limit, "sanity"); 5191 assert(!rp->discovery_is_atomic(), "check this code"); 5192 5193 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5194 for (uint idx = worker_id; idx < limit; idx += stride) { 5195 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5196 5197 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5198 while (iter.has_next()) { 5199 // Since discovery is not atomic for the CM ref processor, we 5200 // can see some null referent objects. 5201 iter.load_ptrs(DEBUG_ONLY(true)); 5202 oop ref = iter.obj(); 5203 5204 // This will filter nulls. 5205 if (iter.is_referent_alive()) { 5206 iter.make_referent_alive(); 5207 } 5208 iter.move_to_next(); 5209 } 5210 } 5211 5212 // Drain the queue - which may cause stealing 5213 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5214 drain_queue.do_void(); 5215 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5216 assert(pss.queue_is_empty(), "should be"); 5217 } 5218 }; 5219 5220 // Weak Reference processing during an evacuation pause (part 1). 5221 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5222 double ref_proc_start = os::elapsedTime(); 5223 5224 ReferenceProcessor* rp = _ref_processor_stw; 5225 assert(rp->discovery_enabled(), "should have been enabled"); 5226 5227 // Any reference objects, in the collection set, that were 'discovered' 5228 // by the CM ref processor should have already been copied (either by 5229 // applying the external root copy closure to the discovered lists, or 5230 // by following an RSet entry). 5231 // 5232 // But some of the referents, that are in the collection set, that these 5233 // reference objects point to may not have been copied: the STW ref 5234 // processor would have seen that the reference object had already 5235 // been 'discovered' and would have skipped discovering the reference, 5236 // but would not have treated the reference object as a regular oop. 5237 // As a result the copy closure would not have been applied to the 5238 // referent object. 5239 // 5240 // We need to explicitly copy these referent objects - the references 5241 // will be processed at the end of remarking. 5242 // 5243 // We also need to do this copying before we process the reference 5244 // objects discovered by the STW ref processor in case one of these 5245 // referents points to another object which is also referenced by an 5246 // object discovered by the STW ref processor. 5247 5248 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers"); 5249 5250 set_par_threads(no_of_gc_workers); 5251 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5252 no_of_gc_workers, 5253 _task_queues); 5254 5255 workers()->run_task(&keep_cm_referents); 5256 5257 set_par_threads(0); 5258 5259 // Closure to test whether a referent is alive. 5260 G1STWIsAliveClosure is_alive(this); 5261 5262 // Even when parallel reference processing is enabled, the processing 5263 // of JNI refs is serial and performed serially by the current thread 5264 // rather than by a worker. The following PSS will be used for processing 5265 // JNI refs. 5266 5267 // Use only a single queue for this PSS. 5268 G1ParScanThreadState pss(this, 0, NULL); 5269 5270 // We do not embed a reference processor in the copying/scanning 5271 // closures while we're actually processing the discovered 5272 // reference objects. 5273 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5274 5275 pss.set_evac_failure_closure(&evac_failure_cl); 5276 5277 assert(pss.queue_is_empty(), "pre-condition"); 5278 5279 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5280 5281 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5282 5283 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5284 5285 if (g1_policy()->during_initial_mark_pause()) { 5286 // We also need to mark copied objects. 5287 copy_non_heap_cl = ©_mark_non_heap_cl; 5288 } 5289 5290 // Keep alive closure. 5291 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss); 5292 5293 // Serial Complete GC closure 5294 G1STWDrainQueueClosure drain_queue(this, &pss); 5295 5296 // Setup the soft refs policy... 5297 rp->setup_policy(false); 5298 5299 ReferenceProcessorStats stats; 5300 if (!rp->processing_is_mt()) { 5301 // Serial reference processing... 5302 stats = rp->process_discovered_references(&is_alive, 5303 &keep_alive, 5304 &drain_queue, 5305 NULL, 5306 _gc_timer_stw, 5307 _gc_tracer_stw->gc_id()); 5308 } else { 5309 // Parallel reference processing 5310 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5311 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5312 5313 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5314 stats = rp->process_discovered_references(&is_alive, 5315 &keep_alive, 5316 &drain_queue, 5317 &par_task_executor, 5318 _gc_timer_stw, 5319 _gc_tracer_stw->gc_id()); 5320 } 5321 5322 _gc_tracer_stw->report_gc_reference_stats(stats); 5323 5324 // We have completed copying any necessary live referent objects. 5325 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5326 5327 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5328 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5329 } 5330 5331 // Weak Reference processing during an evacuation pause (part 2). 5332 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5333 double ref_enq_start = os::elapsedTime(); 5334 5335 ReferenceProcessor* rp = _ref_processor_stw; 5336 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5337 5338 // Now enqueue any remaining on the discovered lists on to 5339 // the pending list. 5340 if (!rp->processing_is_mt()) { 5341 // Serial reference processing... 5342 rp->enqueue_discovered_references(); 5343 } else { 5344 // Parallel reference enqueueing 5345 5346 assert(no_of_gc_workers == workers()->active_workers(), 5347 "Need to reset active workers"); 5348 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5349 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5350 5351 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5352 rp->enqueue_discovered_references(&par_task_executor); 5353 } 5354 5355 rp->verify_no_references_recorded(); 5356 assert(!rp->discovery_enabled(), "should have been disabled"); 5357 5358 // FIXME 5359 // CM's reference processing also cleans up the string and symbol tables. 5360 // Should we do that here also? We could, but it is a serial operation 5361 // and could significantly increase the pause time. 5362 5363 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5364 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5365 } 5366 5367 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5368 _expand_heap_after_alloc_failure = true; 5369 _evacuation_failed = false; 5370 5371 // Should G1EvacuationFailureALot be in effect for this GC? 5372 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5373 5374 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5375 5376 // Disable the hot card cache. 5377 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5378 hot_card_cache->reset_hot_cache_claimed_index(); 5379 hot_card_cache->set_use_cache(false); 5380 5381 const uint n_workers = workers()->active_workers(); 5382 assert(UseDynamicNumberOfGCThreads || 5383 n_workers == workers()->total_workers(), 5384 "If not dynamic should be using all the workers"); 5385 set_par_threads(n_workers); 5386 5387 5388 init_for_evac_failure(NULL); 5389 5390 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5391 double start_par_time_sec = os::elapsedTime(); 5392 double end_par_time_sec; 5393 5394 { 5395 G1RootProcessor root_processor(this, n_workers); 5396 G1ParTask g1_par_task(this, _task_queues, &root_processor); 5397 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5398 if (g1_policy()->during_initial_mark_pause()) { 5399 ClassLoaderDataGraph::clear_claimed_marks(); 5400 } 5401 5402 // The individual threads will set their evac-failure closures. 5403 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr(); 5404 // These tasks use ShareHeap::_process_strong_tasks 5405 assert(UseDynamicNumberOfGCThreads || 5406 workers()->active_workers() == workers()->total_workers(), 5407 "If not dynamic should be using all the workers"); 5408 workers()->run_task(&g1_par_task); 5409 end_par_time_sec = os::elapsedTime(); 5410 5411 // Closing the inner scope will execute the destructor 5412 // for the G1RootProcessor object. We record the current 5413 // elapsed time before closing the scope so that time 5414 // taken for the destructor is NOT included in the 5415 // reported parallel time. 5416 } 5417 5418 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 5419 5420 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5421 phase_times->record_par_time(par_time_ms); 5422 5423 double code_root_fixup_time_ms = 5424 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5425 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 5426 5427 set_par_threads(0); 5428 5429 // Process any discovered reference objects - we have 5430 // to do this _before_ we retire the GC alloc regions 5431 // as we may have to copy some 'reachable' referent 5432 // objects (and their reachable sub-graphs) that were 5433 // not copied during the pause. 5434 process_discovered_references(n_workers); 5435 5436 if (G1StringDedup::is_enabled()) { 5437 double fixup_start = os::elapsedTime(); 5438 5439 G1STWIsAliveClosure is_alive(this); 5440 G1KeepAliveClosure keep_alive(this); 5441 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times); 5442 5443 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 5444 phase_times->record_string_dedup_fixup_time(fixup_time_ms); 5445 } 5446 5447 _allocator->release_gc_alloc_regions(n_workers, evacuation_info); 5448 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5449 5450 // Reset and re-enable the hot card cache. 5451 // Note the counts for the cards in the regions in the 5452 // collection set are reset when the collection set is freed. 5453 hot_card_cache->reset_hot_cache(); 5454 hot_card_cache->set_use_cache(true); 5455 5456 purge_code_root_memory(); 5457 5458 finalize_for_evac_failure(); 5459 5460 if (evacuation_failed()) { 5461 remove_self_forwarding_pointers(); 5462 5463 // Reset the G1EvacuationFailureALot counters and flags 5464 // Note: the values are reset only when an actual 5465 // evacuation failure occurs. 5466 NOT_PRODUCT(reset_evacuation_should_fail();) 5467 } 5468 5469 // Enqueue any remaining references remaining on the STW 5470 // reference processor's discovered lists. We need to do 5471 // this after the card table is cleaned (and verified) as 5472 // the act of enqueueing entries on to the pending list 5473 // will log these updates (and dirty their associated 5474 // cards). We need these updates logged to update any 5475 // RSets. 5476 enqueue_discovered_references(n_workers); 5477 5478 redirty_logged_cards(); 5479 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5480 } 5481 5482 void G1CollectedHeap::free_region(HeapRegion* hr, 5483 FreeRegionList* free_list, 5484 bool par, 5485 bool locked) { 5486 assert(!hr->is_free(), "the region should not be free"); 5487 assert(!hr->is_empty(), "the region should not be empty"); 5488 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 5489 assert(free_list != NULL, "pre-condition"); 5490 5491 if (G1VerifyBitmaps) { 5492 MemRegion mr(hr->bottom(), hr->end()); 5493 concurrent_mark()->clearRangePrevBitmap(mr); 5494 } 5495 5496 // Clear the card counts for this region. 5497 // Note: we only need to do this if the region is not young 5498 // (since we don't refine cards in young regions). 5499 if (!hr->is_young()) { 5500 _cg1r->hot_card_cache()->reset_card_counts(hr); 5501 } 5502 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5503 free_list->add_ordered(hr); 5504 } 5505 5506 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5507 FreeRegionList* free_list, 5508 bool par) { 5509 assert(hr->is_starts_humongous(), "this is only for starts humongous regions"); 5510 assert(free_list != NULL, "pre-condition"); 5511 5512 size_t hr_capacity = hr->capacity(); 5513 // We need to read this before we make the region non-humongous, 5514 // otherwise the information will be gone. 5515 uint last_index = hr->last_hc_index(); 5516 hr->clear_humongous(); 5517 free_region(hr, free_list, par); 5518 5519 uint i = hr->hrm_index() + 1; 5520 while (i < last_index) { 5521 HeapRegion* curr_hr = region_at(i); 5522 assert(curr_hr->is_continues_humongous(), "invariant"); 5523 curr_hr->clear_humongous(); 5524 free_region(curr_hr, free_list, par); 5525 i += 1; 5526 } 5527 } 5528 5529 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 5530 const HeapRegionSetCount& humongous_regions_removed) { 5531 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5532 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5533 _old_set.bulk_remove(old_regions_removed); 5534 _humongous_set.bulk_remove(humongous_regions_removed); 5535 } 5536 5537 } 5538 5539 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 5540 assert(list != NULL, "list can't be null"); 5541 if (!list->is_empty()) { 5542 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5543 _hrm.insert_list_into_free_list(list); 5544 } 5545 } 5546 5547 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 5548 _allocator->decrease_used(bytes); 5549 } 5550 5551 class G1ParCleanupCTTask : public AbstractGangTask { 5552 G1SATBCardTableModRefBS* _ct_bs; 5553 G1CollectedHeap* _g1h; 5554 HeapRegion* volatile _su_head; 5555 public: 5556 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 5557 G1CollectedHeap* g1h) : 5558 AbstractGangTask("G1 Par Cleanup CT Task"), 5559 _ct_bs(ct_bs), _g1h(g1h) { } 5560 5561 void work(uint worker_id) { 5562 HeapRegion* r; 5563 while (r = _g1h->pop_dirty_cards_region()) { 5564 clear_cards(r); 5565 } 5566 } 5567 5568 void clear_cards(HeapRegion* r) { 5569 // Cards of the survivors should have already been dirtied. 5570 if (!r->is_survivor()) { 5571 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5572 } 5573 } 5574 }; 5575 5576 #ifndef PRODUCT 5577 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5578 G1CollectedHeap* _g1h; 5579 G1SATBCardTableModRefBS* _ct_bs; 5580 public: 5581 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 5582 : _g1h(g1h), _ct_bs(ct_bs) { } 5583 virtual bool doHeapRegion(HeapRegion* r) { 5584 if (r->is_survivor()) { 5585 _g1h->verify_dirty_region(r); 5586 } else { 5587 _g1h->verify_not_dirty_region(r); 5588 } 5589 return false; 5590 } 5591 }; 5592 5593 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5594 // All of the region should be clean. 5595 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5596 MemRegion mr(hr->bottom(), hr->end()); 5597 ct_bs->verify_not_dirty_region(mr); 5598 } 5599 5600 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5601 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5602 // dirty allocated blocks as they allocate them. The thread that 5603 // retires each region and replaces it with a new one will do a 5604 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5605 // not dirty that area (one less thing to have to do while holding 5606 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5607 // is dirty. 5608 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5609 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5610 if (hr->is_young()) { 5611 ct_bs->verify_g1_young_region(mr); 5612 } else { 5613 ct_bs->verify_dirty_region(mr); 5614 } 5615 } 5616 5617 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5618 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5619 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5620 verify_dirty_region(hr); 5621 } 5622 } 5623 5624 void G1CollectedHeap::verify_dirty_young_regions() { 5625 verify_dirty_young_list(_young_list->first_region()); 5626 } 5627 5628 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 5629 HeapWord* tams, HeapWord* end) { 5630 guarantee(tams <= end, 5631 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, p2i(tams), p2i(end))); 5632 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 5633 if (result < end) { 5634 gclog_or_tty->cr(); 5635 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT, 5636 bitmap_name, p2i(result)); 5637 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT, 5638 bitmap_name, p2i(tams), p2i(end)); 5639 return false; 5640 } 5641 return true; 5642 } 5643 5644 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 5645 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 5646 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 5647 5648 HeapWord* bottom = hr->bottom(); 5649 HeapWord* ptams = hr->prev_top_at_mark_start(); 5650 HeapWord* ntams = hr->next_top_at_mark_start(); 5651 HeapWord* end = hr->end(); 5652 5653 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 5654 5655 bool res_n = true; 5656 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 5657 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 5658 // if we happen to be in that state. 5659 if (mark_in_progress() || !_cmThread->in_progress()) { 5660 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 5661 } 5662 if (!res_p || !res_n) { 5663 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT, 5664 HR_FORMAT_PARAMS(hr)); 5665 gclog_or_tty->print_cr("#### Caller: %s", caller); 5666 return false; 5667 } 5668 return true; 5669 } 5670 5671 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 5672 if (!G1VerifyBitmaps) return; 5673 5674 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 5675 } 5676 5677 class G1VerifyBitmapClosure : public HeapRegionClosure { 5678 private: 5679 const char* _caller; 5680 G1CollectedHeap* _g1h; 5681 bool _failures; 5682 5683 public: 5684 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 5685 _caller(caller), _g1h(g1h), _failures(false) { } 5686 5687 bool failures() { return _failures; } 5688 5689 virtual bool doHeapRegion(HeapRegion* hr) { 5690 if (hr->is_continues_humongous()) return false; 5691 5692 bool result = _g1h->verify_bitmaps(_caller, hr); 5693 if (!result) { 5694 _failures = true; 5695 } 5696 return false; 5697 } 5698 }; 5699 5700 void G1CollectedHeap::check_bitmaps(const char* caller) { 5701 if (!G1VerifyBitmaps) return; 5702 5703 G1VerifyBitmapClosure cl(caller, this); 5704 heap_region_iterate(&cl); 5705 guarantee(!cl.failures(), "bitmap verification"); 5706 } 5707 5708 class G1CheckCSetFastTableClosure : public HeapRegionClosure { 5709 private: 5710 bool _failures; 5711 public: 5712 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { } 5713 5714 virtual bool doHeapRegion(HeapRegion* hr) { 5715 uint i = hr->hrm_index(); 5716 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i); 5717 if (hr->is_humongous()) { 5718 if (hr->in_collection_set()) { 5719 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i); 5720 _failures = true; 5721 return true; 5722 } 5723 if (cset_state.is_in_cset()) { 5724 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i); 5725 _failures = true; 5726 return true; 5727 } 5728 if (hr->is_continues_humongous() && cset_state.is_humongous()) { 5729 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i); 5730 _failures = true; 5731 return true; 5732 } 5733 } else { 5734 if (cset_state.is_humongous()) { 5735 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i); 5736 _failures = true; 5737 return true; 5738 } 5739 if (hr->in_collection_set() != cset_state.is_in_cset()) { 5740 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u", 5741 hr->in_collection_set(), cset_state.value(), i); 5742 _failures = true; 5743 return true; 5744 } 5745 if (cset_state.is_in_cset()) { 5746 if (hr->is_young() != (cset_state.is_young())) { 5747 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u", 5748 hr->is_young(), cset_state.value(), i); 5749 _failures = true; 5750 return true; 5751 } 5752 if (hr->is_old() != (cset_state.is_old())) { 5753 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u", 5754 hr->is_old(), cset_state.value(), i); 5755 _failures = true; 5756 return true; 5757 } 5758 } 5759 } 5760 return false; 5761 } 5762 5763 bool failures() const { return _failures; } 5764 }; 5765 5766 bool G1CollectedHeap::check_cset_fast_test() { 5767 G1CheckCSetFastTableClosure cl; 5768 _hrm.iterate(&cl); 5769 return !cl.failures(); 5770 } 5771 #endif // PRODUCT 5772 5773 void G1CollectedHeap::cleanUpCardTable() { 5774 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5775 double start = os::elapsedTime(); 5776 5777 { 5778 // Iterate over the dirty cards region list. 5779 G1ParCleanupCTTask cleanup_task(ct_bs, this); 5780 5781 set_par_threads(); 5782 workers()->run_task(&cleanup_task); 5783 set_par_threads(0); 5784 #ifndef PRODUCT 5785 if (G1VerifyCTCleanup || VerifyAfterGC) { 5786 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 5787 heap_region_iterate(&cleanup_verifier); 5788 } 5789 #endif 5790 } 5791 5792 double elapsed = os::elapsedTime() - start; 5793 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 5794 } 5795 5796 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 5797 size_t pre_used = 0; 5798 FreeRegionList local_free_list("Local List for CSet Freeing"); 5799 5800 double young_time_ms = 0.0; 5801 double non_young_time_ms = 0.0; 5802 5803 // Since the collection set is a superset of the the young list, 5804 // all we need to do to clear the young list is clear its 5805 // head and length, and unlink any young regions in the code below 5806 _young_list->clear(); 5807 5808 G1CollectorPolicy* policy = g1_policy(); 5809 5810 double start_sec = os::elapsedTime(); 5811 bool non_young = true; 5812 5813 HeapRegion* cur = cs_head; 5814 int age_bound = -1; 5815 size_t rs_lengths = 0; 5816 5817 while (cur != NULL) { 5818 assert(!is_on_master_free_list(cur), "sanity"); 5819 if (non_young) { 5820 if (cur->is_young()) { 5821 double end_sec = os::elapsedTime(); 5822 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5823 non_young_time_ms += elapsed_ms; 5824 5825 start_sec = os::elapsedTime(); 5826 non_young = false; 5827 } 5828 } else { 5829 if (!cur->is_young()) { 5830 double end_sec = os::elapsedTime(); 5831 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5832 young_time_ms += elapsed_ms; 5833 5834 start_sec = os::elapsedTime(); 5835 non_young = true; 5836 } 5837 } 5838 5839 rs_lengths += cur->rem_set()->occupied_locked(); 5840 5841 HeapRegion* next = cur->next_in_collection_set(); 5842 assert(cur->in_collection_set(), "bad CS"); 5843 cur->set_next_in_collection_set(NULL); 5844 clear_in_cset(cur); 5845 5846 if (cur->is_young()) { 5847 int index = cur->young_index_in_cset(); 5848 assert(index != -1, "invariant"); 5849 assert((uint) index < policy->young_cset_region_length(), "invariant"); 5850 size_t words_survived = _surviving_young_words[index]; 5851 cur->record_surv_words_in_group(words_survived); 5852 5853 // At this point the we have 'popped' cur from the collection set 5854 // (linked via next_in_collection_set()) but it is still in the 5855 // young list (linked via next_young_region()). Clear the 5856 // _next_young_region field. 5857 cur->set_next_young_region(NULL); 5858 } else { 5859 int index = cur->young_index_in_cset(); 5860 assert(index == -1, "invariant"); 5861 } 5862 5863 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 5864 (!cur->is_young() && cur->young_index_in_cset() == -1), 5865 "invariant" ); 5866 5867 if (!cur->evacuation_failed()) { 5868 MemRegion used_mr = cur->used_region(); 5869 5870 // And the region is empty. 5871 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 5872 pre_used += cur->used(); 5873 free_region(cur, &local_free_list, false /* par */, true /* locked */); 5874 } else { 5875 cur->uninstall_surv_rate_group(); 5876 if (cur->is_young()) { 5877 cur->set_young_index_in_cset(-1); 5878 } 5879 cur->set_evacuation_failed(false); 5880 // The region is now considered to be old. 5881 cur->set_old(); 5882 _old_set.add(cur); 5883 evacuation_info.increment_collectionset_used_after(cur->used()); 5884 } 5885 cur = next; 5886 } 5887 5888 evacuation_info.set_regions_freed(local_free_list.length()); 5889 policy->record_max_rs_lengths(rs_lengths); 5890 policy->cset_regions_freed(); 5891 5892 double end_sec = os::elapsedTime(); 5893 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5894 5895 if (non_young) { 5896 non_young_time_ms += elapsed_ms; 5897 } else { 5898 young_time_ms += elapsed_ms; 5899 } 5900 5901 prepend_to_freelist(&local_free_list); 5902 decrement_summary_bytes(pre_used); 5903 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 5904 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 5905 } 5906 5907 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 5908 private: 5909 FreeRegionList* _free_region_list; 5910 HeapRegionSet* _proxy_set; 5911 HeapRegionSetCount _humongous_regions_removed; 5912 size_t _freed_bytes; 5913 public: 5914 5915 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 5916 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 5917 } 5918 5919 virtual bool doHeapRegion(HeapRegion* r) { 5920 if (!r->is_starts_humongous()) { 5921 return false; 5922 } 5923 5924 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 5925 5926 oop obj = (oop)r->bottom(); 5927 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 5928 5929 // The following checks whether the humongous object is live are sufficient. 5930 // The main additional check (in addition to having a reference from the roots 5931 // or the young gen) is whether the humongous object has a remembered set entry. 5932 // 5933 // A humongous object cannot be live if there is no remembered set for it 5934 // because: 5935 // - there can be no references from within humongous starts regions referencing 5936 // the object because we never allocate other objects into them. 5937 // (I.e. there are no intra-region references that may be missed by the 5938 // remembered set) 5939 // - as soon there is a remembered set entry to the humongous starts region 5940 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 5941 // until the end of a concurrent mark. 5942 // 5943 // It is not required to check whether the object has been found dead by marking 5944 // or not, in fact it would prevent reclamation within a concurrent cycle, as 5945 // all objects allocated during that time are considered live. 5946 // SATB marking is even more conservative than the remembered set. 5947 // So if at this point in the collection there is no remembered set entry, 5948 // nobody has a reference to it. 5949 // At the start of collection we flush all refinement logs, and remembered sets 5950 // are completely up-to-date wrt to references to the humongous object. 5951 // 5952 // Other implementation considerations: 5953 // - never consider object arrays at this time because they would pose 5954 // considerable effort for cleaning up the the remembered sets. This is 5955 // required because stale remembered sets might reference locations that 5956 // are currently allocated into. 5957 uint region_idx = r->hrm_index(); 5958 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 5959 !r->rem_set()->is_empty()) { 5960 5961 if (G1TraceEagerReclaimHumongousObjects) { 5962 gclog_or_tty->print_cr("Live humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length %u with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d", 5963 region_idx, 5964 (size_t)obj->size() * HeapWordSize, 5965 p2i(r->bottom()), 5966 r->region_num(), 5967 r->rem_set()->occupied(), 5968 r->rem_set()->strong_code_roots_list_length(), 5969 next_bitmap->isMarked(r->bottom()), 5970 g1h->is_humongous_reclaim_candidate(region_idx), 5971 obj->is_typeArray() 5972 ); 5973 } 5974 5975 return false; 5976 } 5977 5978 guarantee(obj->is_typeArray(), 5979 err_msg("Only eagerly reclaiming type arrays is supported, but the object " 5980 PTR_FORMAT " is not.", 5981 p2i(r->bottom()))); 5982 5983 if (G1TraceEagerReclaimHumongousObjects) { 5984 gclog_or_tty->print_cr("Dead humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length %u with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d", 5985 region_idx, 5986 (size_t)obj->size() * HeapWordSize, 5987 p2i(r->bottom()), 5988 r->region_num(), 5989 r->rem_set()->occupied(), 5990 r->rem_set()->strong_code_roots_list_length(), 5991 next_bitmap->isMarked(r->bottom()), 5992 g1h->is_humongous_reclaim_candidate(region_idx), 5993 obj->is_typeArray() 5994 ); 5995 } 5996 // Need to clear mark bit of the humongous object if already set. 5997 if (next_bitmap->isMarked(r->bottom())) { 5998 next_bitmap->clear(r->bottom()); 5999 } 6000 _freed_bytes += r->used(); 6001 r->set_containing_set(NULL); 6002 _humongous_regions_removed.increment(1u, r->capacity()); 6003 g1h->free_humongous_region(r, _free_region_list, false); 6004 6005 return false; 6006 } 6007 6008 HeapRegionSetCount& humongous_free_count() { 6009 return _humongous_regions_removed; 6010 } 6011 6012 size_t bytes_freed() const { 6013 return _freed_bytes; 6014 } 6015 6016 size_t humongous_reclaimed() const { 6017 return _humongous_regions_removed.length(); 6018 } 6019 }; 6020 6021 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 6022 assert_at_safepoint(true); 6023 6024 if (!G1EagerReclaimHumongousObjects || 6025 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) { 6026 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 6027 return; 6028 } 6029 6030 double start_time = os::elapsedTime(); 6031 6032 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 6033 6034 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 6035 heap_region_iterate(&cl); 6036 6037 HeapRegionSetCount empty_set; 6038 remove_from_old_sets(empty_set, cl.humongous_free_count()); 6039 6040 G1HRPrinter* hrp = hr_printer(); 6041 if (hrp->is_active()) { 6042 FreeRegionListIterator iter(&local_cleanup_list); 6043 while (iter.more_available()) { 6044 HeapRegion* hr = iter.get_next(); 6045 hrp->cleanup(hr); 6046 } 6047 } 6048 6049 prepend_to_freelist(&local_cleanup_list); 6050 decrement_summary_bytes(cl.bytes_freed()); 6051 6052 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 6053 cl.humongous_reclaimed()); 6054 } 6055 6056 // This routine is similar to the above but does not record 6057 // any policy statistics or update free lists; we are abandoning 6058 // the current incremental collection set in preparation of a 6059 // full collection. After the full GC we will start to build up 6060 // the incremental collection set again. 6061 // This is only called when we're doing a full collection 6062 // and is immediately followed by the tearing down of the young list. 6063 6064 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6065 HeapRegion* cur = cs_head; 6066 6067 while (cur != NULL) { 6068 HeapRegion* next = cur->next_in_collection_set(); 6069 assert(cur->in_collection_set(), "bad CS"); 6070 cur->set_next_in_collection_set(NULL); 6071 clear_in_cset(cur); 6072 cur->set_young_index_in_cset(-1); 6073 cur = next; 6074 } 6075 } 6076 6077 void G1CollectedHeap::set_free_regions_coming() { 6078 if (G1ConcRegionFreeingVerbose) { 6079 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6080 "setting free regions coming"); 6081 } 6082 6083 assert(!free_regions_coming(), "pre-condition"); 6084 _free_regions_coming = true; 6085 } 6086 6087 void G1CollectedHeap::reset_free_regions_coming() { 6088 assert(free_regions_coming(), "pre-condition"); 6089 6090 { 6091 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6092 _free_regions_coming = false; 6093 SecondaryFreeList_lock->notify_all(); 6094 } 6095 6096 if (G1ConcRegionFreeingVerbose) { 6097 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6098 "reset free regions coming"); 6099 } 6100 } 6101 6102 void G1CollectedHeap::wait_while_free_regions_coming() { 6103 // Most of the time we won't have to wait, so let's do a quick test 6104 // first before we take the lock. 6105 if (!free_regions_coming()) { 6106 return; 6107 } 6108 6109 if (G1ConcRegionFreeingVerbose) { 6110 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6111 "waiting for free regions"); 6112 } 6113 6114 { 6115 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6116 while (free_regions_coming()) { 6117 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6118 } 6119 } 6120 6121 if (G1ConcRegionFreeingVerbose) { 6122 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6123 "done waiting for free regions"); 6124 } 6125 } 6126 6127 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6128 _young_list->push_region(hr); 6129 } 6130 6131 class NoYoungRegionsClosure: public HeapRegionClosure { 6132 private: 6133 bool _success; 6134 public: 6135 NoYoungRegionsClosure() : _success(true) { } 6136 bool doHeapRegion(HeapRegion* r) { 6137 if (r->is_young()) { 6138 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6139 p2i(r->bottom()), p2i(r->end())); 6140 _success = false; 6141 } 6142 return false; 6143 } 6144 bool success() { return _success; } 6145 }; 6146 6147 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6148 bool ret = _young_list->check_list_empty(check_sample); 6149 6150 if (check_heap) { 6151 NoYoungRegionsClosure closure; 6152 heap_region_iterate(&closure); 6153 ret = ret && closure.success(); 6154 } 6155 6156 return ret; 6157 } 6158 6159 class TearDownRegionSetsClosure : public HeapRegionClosure { 6160 private: 6161 HeapRegionSet *_old_set; 6162 6163 public: 6164 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6165 6166 bool doHeapRegion(HeapRegion* r) { 6167 if (r->is_old()) { 6168 _old_set->remove(r); 6169 } else { 6170 // We ignore free regions, we'll empty the free list afterwards. 6171 // We ignore young regions, we'll empty the young list afterwards. 6172 // We ignore humongous regions, we're not tearing down the 6173 // humongous regions set. 6174 assert(r->is_free() || r->is_young() || r->is_humongous(), 6175 "it cannot be another type"); 6176 } 6177 return false; 6178 } 6179 6180 ~TearDownRegionSetsClosure() { 6181 assert(_old_set->is_empty(), "post-condition"); 6182 } 6183 }; 6184 6185 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6186 assert_at_safepoint(true /* should_be_vm_thread */); 6187 6188 if (!free_list_only) { 6189 TearDownRegionSetsClosure cl(&_old_set); 6190 heap_region_iterate(&cl); 6191 6192 // Note that emptying the _young_list is postponed and instead done as 6193 // the first step when rebuilding the regions sets again. The reason for 6194 // this is that during a full GC string deduplication needs to know if 6195 // a collected region was young or old when the full GC was initiated. 6196 } 6197 _hrm.remove_all_free_regions(); 6198 } 6199 6200 class RebuildRegionSetsClosure : public HeapRegionClosure { 6201 private: 6202 bool _free_list_only; 6203 HeapRegionSet* _old_set; 6204 HeapRegionManager* _hrm; 6205 size_t _total_used; 6206 6207 public: 6208 RebuildRegionSetsClosure(bool free_list_only, 6209 HeapRegionSet* old_set, HeapRegionManager* hrm) : 6210 _free_list_only(free_list_only), 6211 _old_set(old_set), _hrm(hrm), _total_used(0) { 6212 assert(_hrm->num_free_regions() == 0, "pre-condition"); 6213 if (!free_list_only) { 6214 assert(_old_set->is_empty(), "pre-condition"); 6215 } 6216 } 6217 6218 bool doHeapRegion(HeapRegion* r) { 6219 if (r->is_continues_humongous()) { 6220 return false; 6221 } 6222 6223 if (r->is_empty()) { 6224 // Add free regions to the free list 6225 r->set_free(); 6226 r->set_allocation_context(AllocationContext::system()); 6227 _hrm->insert_into_free_list(r); 6228 } else if (!_free_list_only) { 6229 assert(!r->is_young(), "we should not come across young regions"); 6230 6231 if (r->is_humongous()) { 6232 // We ignore humongous regions, we left the humongous set unchanged 6233 } else { 6234 // Objects that were compacted would have ended up on regions 6235 // that were previously old or free. 6236 assert(r->is_free() || r->is_old(), "invariant"); 6237 // We now consider them old, so register as such. 6238 r->set_old(); 6239 _old_set->add(r); 6240 } 6241 _total_used += r->used(); 6242 } 6243 6244 return false; 6245 } 6246 6247 size_t total_used() { 6248 return _total_used; 6249 } 6250 }; 6251 6252 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6253 assert_at_safepoint(true /* should_be_vm_thread */); 6254 6255 if (!free_list_only) { 6256 _young_list->empty_list(); 6257 } 6258 6259 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 6260 heap_region_iterate(&cl); 6261 6262 if (!free_list_only) { 6263 _allocator->set_used(cl.total_used()); 6264 } 6265 assert(_allocator->used_unlocked() == recalculate_used(), 6266 err_msg("inconsistent _allocator->used_unlocked(), " 6267 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6268 _allocator->used_unlocked(), recalculate_used())); 6269 } 6270 6271 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6272 _refine_cte_cl->set_concurrent(concurrent); 6273 } 6274 6275 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6276 HeapRegion* hr = heap_region_containing(p); 6277 return hr->is_in(p); 6278 } 6279 6280 // Methods for the mutator alloc region 6281 6282 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6283 bool force) { 6284 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6285 assert(!force || g1_policy()->can_expand_young_list(), 6286 "if force is true we should be able to expand the young list"); 6287 bool young_list_full = g1_policy()->is_young_list_full(); 6288 if (force || !young_list_full) { 6289 HeapRegion* new_alloc_region = new_region(word_size, 6290 false /* is_old */, 6291 false /* do_expand */); 6292 if (new_alloc_region != NULL) { 6293 set_region_short_lived_locked(new_alloc_region); 6294 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6295 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6296 return new_alloc_region; 6297 } 6298 } 6299 return NULL; 6300 } 6301 6302 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6303 size_t allocated_bytes) { 6304 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6305 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 6306 6307 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6308 _allocator->increase_used(allocated_bytes); 6309 _hr_printer.retire(alloc_region); 6310 // We update the eden sizes here, when the region is retired, 6311 // instead of when it's allocated, since this is the point that its 6312 // used space has been recored in _summary_bytes_used. 6313 g1mm()->update_eden_size(); 6314 } 6315 6316 void G1CollectedHeap::set_par_threads() { 6317 // Don't change the number of workers. Use the value previously set 6318 // in the workgroup. 6319 uint n_workers = workers()->active_workers(); 6320 assert(UseDynamicNumberOfGCThreads || 6321 n_workers == workers()->total_workers(), 6322 "Otherwise should be using the total number of workers"); 6323 if (n_workers == 0) { 6324 assert(false, "Should have been set in prior evacuation pause."); 6325 n_workers = ParallelGCThreads; 6326 workers()->set_active_workers(n_workers); 6327 } 6328 set_par_threads(n_workers); 6329 } 6330 6331 // Methods for the GC alloc regions 6332 6333 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6334 uint count, 6335 InCSetState dest) { 6336 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6337 6338 if (count < g1_policy()->max_regions(dest)) { 6339 const bool is_survivor = (dest.is_young()); 6340 HeapRegion* new_alloc_region = new_region(word_size, 6341 !is_survivor, 6342 true /* do_expand */); 6343 if (new_alloc_region != NULL) { 6344 // We really only need to do this for old regions given that we 6345 // should never scan survivors. But it doesn't hurt to do it 6346 // for survivors too. 6347 new_alloc_region->record_timestamp(); 6348 if (is_survivor) { 6349 new_alloc_region->set_survivor(); 6350 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6351 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6352 } else { 6353 new_alloc_region->set_old(); 6354 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6355 check_bitmaps("Old Region Allocation", new_alloc_region); 6356 } 6357 bool during_im = g1_policy()->during_initial_mark_pause(); 6358 new_alloc_region->note_start_of_copying(during_im); 6359 return new_alloc_region; 6360 } 6361 } 6362 return NULL; 6363 } 6364 6365 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6366 size_t allocated_bytes, 6367 InCSetState dest) { 6368 bool during_im = g1_policy()->during_initial_mark_pause(); 6369 alloc_region->note_end_of_copying(during_im); 6370 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6371 if (dest.is_young()) { 6372 young_list()->add_survivor_region(alloc_region); 6373 } else { 6374 _old_set.add(alloc_region); 6375 } 6376 _hr_printer.retire(alloc_region); 6377 } 6378 6379 // Heap region set verification 6380 6381 class VerifyRegionListsClosure : public HeapRegionClosure { 6382 private: 6383 HeapRegionSet* _old_set; 6384 HeapRegionSet* _humongous_set; 6385 HeapRegionManager* _hrm; 6386 6387 public: 6388 HeapRegionSetCount _old_count; 6389 HeapRegionSetCount _humongous_count; 6390 HeapRegionSetCount _free_count; 6391 6392 VerifyRegionListsClosure(HeapRegionSet* old_set, 6393 HeapRegionSet* humongous_set, 6394 HeapRegionManager* hrm) : 6395 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm), 6396 _old_count(), _humongous_count(), _free_count(){ } 6397 6398 bool doHeapRegion(HeapRegion* hr) { 6399 if (hr->is_continues_humongous()) { 6400 return false; 6401 } 6402 6403 if (hr->is_young()) { 6404 // TODO 6405 } else if (hr->is_starts_humongous()) { 6406 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index())); 6407 _humongous_count.increment(1u, hr->capacity()); 6408 } else if (hr->is_empty()) { 6409 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index())); 6410 _free_count.increment(1u, hr->capacity()); 6411 } else if (hr->is_old()) { 6412 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index())); 6413 _old_count.increment(1u, hr->capacity()); 6414 } else { 6415 ShouldNotReachHere(); 6416 } 6417 return false; 6418 } 6419 6420 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) { 6421 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 6422 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6423 old_set->total_capacity_bytes(), _old_count.capacity())); 6424 6425 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 6426 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6427 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 6428 6429 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())); 6430 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6431 free_list->total_capacity_bytes(), _free_count.capacity())); 6432 } 6433 }; 6434 6435 void G1CollectedHeap::verify_region_sets() { 6436 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6437 6438 // First, check the explicit lists. 6439 _hrm.verify(); 6440 { 6441 // Given that a concurrent operation might be adding regions to 6442 // the secondary free list we have to take the lock before 6443 // verifying it. 6444 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6445 _secondary_free_list.verify_list(); 6446 } 6447 6448 // If a concurrent region freeing operation is in progress it will 6449 // be difficult to correctly attributed any free regions we come 6450 // across to the correct free list given that they might belong to 6451 // one of several (free_list, secondary_free_list, any local lists, 6452 // etc.). So, if that's the case we will skip the rest of the 6453 // verification operation. Alternatively, waiting for the concurrent 6454 // operation to complete will have a non-trivial effect on the GC's 6455 // operation (no concurrent operation will last longer than the 6456 // interval between two calls to verification) and it might hide 6457 // any issues that we would like to catch during testing. 6458 if (free_regions_coming()) { 6459 return; 6460 } 6461 6462 // Make sure we append the secondary_free_list on the free_list so 6463 // that all free regions we will come across can be safely 6464 // attributed to the free_list. 6465 append_secondary_free_list_if_not_empty_with_lock(); 6466 6467 // Finally, make sure that the region accounting in the lists is 6468 // consistent with what we see in the heap. 6469 6470 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm); 6471 heap_region_iterate(&cl); 6472 cl.verify_counts(&_old_set, &_humongous_set, &_hrm); 6473 } 6474 6475 // Optimized nmethod scanning 6476 6477 class RegisterNMethodOopClosure: public OopClosure { 6478 G1CollectedHeap* _g1h; 6479 nmethod* _nm; 6480 6481 template <class T> void do_oop_work(T* p) { 6482 T heap_oop = oopDesc::load_heap_oop(p); 6483 if (!oopDesc::is_null(heap_oop)) { 6484 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6485 HeapRegion* hr = _g1h->heap_region_containing(obj); 6486 assert(!hr->is_continues_humongous(), 6487 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6488 " starting at "HR_FORMAT, 6489 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6490 6491 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 6492 hr->add_strong_code_root_locked(_nm); 6493 } 6494 } 6495 6496 public: 6497 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6498 _g1h(g1h), _nm(nm) {} 6499 6500 void do_oop(oop* p) { do_oop_work(p); } 6501 void do_oop(narrowOop* p) { do_oop_work(p); } 6502 }; 6503 6504 class UnregisterNMethodOopClosure: public OopClosure { 6505 G1CollectedHeap* _g1h; 6506 nmethod* _nm; 6507 6508 template <class T> void do_oop_work(T* p) { 6509 T heap_oop = oopDesc::load_heap_oop(p); 6510 if (!oopDesc::is_null(heap_oop)) { 6511 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6512 HeapRegion* hr = _g1h->heap_region_containing(obj); 6513 assert(!hr->is_continues_humongous(), 6514 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6515 " starting at "HR_FORMAT, 6516 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6517 6518 hr->remove_strong_code_root(_nm); 6519 } 6520 } 6521 6522 public: 6523 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6524 _g1h(g1h), _nm(nm) {} 6525 6526 void do_oop(oop* p) { do_oop_work(p); } 6527 void do_oop(narrowOop* p) { do_oop_work(p); } 6528 }; 6529 6530 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6531 CollectedHeap::register_nmethod(nm); 6532 6533 guarantee(nm != NULL, "sanity"); 6534 RegisterNMethodOopClosure reg_cl(this, nm); 6535 nm->oops_do(®_cl); 6536 } 6537 6538 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6539 CollectedHeap::unregister_nmethod(nm); 6540 6541 guarantee(nm != NULL, "sanity"); 6542 UnregisterNMethodOopClosure reg_cl(this, nm); 6543 nm->oops_do(®_cl, true); 6544 } 6545 6546 void G1CollectedHeap::purge_code_root_memory() { 6547 double purge_start = os::elapsedTime(); 6548 G1CodeRootSet::purge(); 6549 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6550 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6551 } 6552 6553 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6554 G1CollectedHeap* _g1h; 6555 6556 public: 6557 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6558 _g1h(g1h) {} 6559 6560 void do_code_blob(CodeBlob* cb) { 6561 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6562 if (nm == NULL) { 6563 return; 6564 } 6565 6566 if (ScavengeRootsInCode) { 6567 _g1h->register_nmethod(nm); 6568 } 6569 } 6570 }; 6571 6572 void G1CollectedHeap::rebuild_strong_code_roots() { 6573 RebuildStrongCodeRootClosure blob_cl(this); 6574 CodeCache::blobs_do(&blob_cl); 6575 }