1 /* 2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/metadataOnStackMark.hpp" 27 #include "classfile/stringTable.hpp" 28 #include "code/codeCache.hpp" 29 #include "code/icBuffer.hpp" 30 #include "gc/g1/bufferingOopClosure.hpp" 31 #include "gc/g1/concurrentG1Refine.hpp" 32 #include "gc/g1/concurrentG1RefineThread.hpp" 33 #include "gc/g1/concurrentMarkThread.inline.hpp" 34 #include "gc/g1/g1Allocator.inline.hpp" 35 #include "gc/g1/g1CollectedHeap.inline.hpp" 36 #include "gc/g1/g1CollectorPolicy.hpp" 37 #include "gc/g1/g1CollectorState.hpp" 38 #include "gc/g1/g1ErgoVerbose.hpp" 39 #include "gc/g1/g1EvacFailure.hpp" 40 #include "gc/g1/g1GCPhaseTimes.hpp" 41 #include "gc/g1/g1Log.hpp" 42 #include "gc/g1/g1MarkSweep.hpp" 43 #include "gc/g1/g1OopClosures.inline.hpp" 44 #include "gc/g1/g1ParScanThreadState.inline.hpp" 45 #include "gc/g1/g1RegionToSpaceMapper.hpp" 46 #include "gc/g1/g1RemSet.inline.hpp" 47 #include "gc/g1/g1RootProcessor.hpp" 48 #include "gc/g1/g1StringDedup.hpp" 49 #include "gc/g1/g1YCTypes.hpp" 50 #include "gc/g1/heapRegion.inline.hpp" 51 #include "gc/g1/heapRegionRemSet.hpp" 52 #include "gc/g1/heapRegionSet.inline.hpp" 53 #include "gc/g1/suspendibleThreadSet.hpp" 54 #include "gc/g1/vm_operations_g1.hpp" 55 #include "gc/shared/gcHeapSummary.hpp" 56 #include "gc/shared/gcLocker.inline.hpp" 57 #include "gc/shared/gcTimer.hpp" 58 #include "gc/shared/gcTrace.hpp" 59 #include "gc/shared/gcTraceTime.hpp" 60 #include "gc/shared/generationSpec.hpp" 61 #include "gc/shared/isGCActiveMark.hpp" 62 #include "gc/shared/referenceProcessor.hpp" 63 #include "gc/shared/taskqueue.inline.hpp" 64 #include "memory/allocation.hpp" 65 #include "memory/iterator.hpp" 66 #include "oops/oop.inline.hpp" 67 #include "runtime/atomic.inline.hpp" 68 #include "runtime/init.hpp" 69 #include "runtime/orderAccess.inline.hpp" 70 #include "runtime/vmThread.hpp" 71 #include "utilities/globalDefinitions.hpp" 72 #include "utilities/stack.inline.hpp" 73 74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 75 76 // turn it on so that the contents of the young list (scan-only / 77 // to-be-collected) are printed at "strategic" points before / during 78 // / after the collection --- this is useful for debugging 79 #define YOUNG_LIST_VERBOSE 0 80 // CURRENT STATUS 81 // This file is under construction. Search for "FIXME". 82 83 // INVARIANTS/NOTES 84 // 85 // All allocation activity covered by the G1CollectedHeap interface is 86 // serialized by acquiring the HeapLock. This happens in mem_allocate 87 // and allocate_new_tlab, which are the "entry" points to the 88 // allocation code from the rest of the JVM. (Note that this does not 89 // apply to TLAB allocation, which is not part of this interface: it 90 // is done by clients of this interface.) 91 92 // Local to this file. 93 94 class RefineCardTableEntryClosure: public CardTableEntryClosure { 95 bool _concurrent; 96 public: 97 RefineCardTableEntryClosure() : _concurrent(true) { } 98 99 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 100 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 101 // This path is executed by the concurrent refine or mutator threads, 102 // concurrently, and so we do not care if card_ptr contains references 103 // that point into the collection set. 104 assert(!oops_into_cset, "should be"); 105 106 if (_concurrent && SuspendibleThreadSet::should_yield()) { 107 // Caller will actually yield. 108 return false; 109 } 110 // Otherwise, we finished successfully; return true. 111 return true; 112 } 113 114 void set_concurrent(bool b) { _concurrent = b; } 115 }; 116 117 118 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 119 private: 120 size_t _num_processed; 121 122 public: 123 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { } 124 125 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 126 *card_ptr = CardTableModRefBS::dirty_card_val(); 127 _num_processed++; 128 return true; 129 } 130 131 size_t num_processed() const { return _num_processed; } 132 }; 133 134 YoungList::YoungList(G1CollectedHeap* g1h) : 135 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 136 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 137 guarantee(check_list_empty(false), "just making sure..."); 138 } 139 140 void YoungList::push_region(HeapRegion *hr) { 141 assert(!hr->is_young(), "should not already be young"); 142 assert(hr->get_next_young_region() == NULL, "cause it should!"); 143 144 hr->set_next_young_region(_head); 145 _head = hr; 146 147 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 148 ++_length; 149 } 150 151 void YoungList::add_survivor_region(HeapRegion* hr) { 152 assert(hr->is_survivor(), "should be flagged as survivor region"); 153 assert(hr->get_next_young_region() == NULL, "cause it should!"); 154 155 hr->set_next_young_region(_survivor_head); 156 if (_survivor_head == NULL) { 157 _survivor_tail = hr; 158 } 159 _survivor_head = hr; 160 ++_survivor_length; 161 } 162 163 void YoungList::empty_list(HeapRegion* list) { 164 while (list != NULL) { 165 HeapRegion* next = list->get_next_young_region(); 166 list->set_next_young_region(NULL); 167 list->uninstall_surv_rate_group(); 168 // This is called before a Full GC and all the non-empty / 169 // non-humongous regions at the end of the Full GC will end up as 170 // old anyway. 171 list->set_old(); 172 list = next; 173 } 174 } 175 176 void YoungList::empty_list() { 177 assert(check_list_well_formed(), "young list should be well formed"); 178 179 empty_list(_head); 180 _head = NULL; 181 _length = 0; 182 183 empty_list(_survivor_head); 184 _survivor_head = NULL; 185 _survivor_tail = NULL; 186 _survivor_length = 0; 187 188 _last_sampled_rs_lengths = 0; 189 190 assert(check_list_empty(false), "just making sure..."); 191 } 192 193 bool YoungList::check_list_well_formed() { 194 bool ret = true; 195 196 uint length = 0; 197 HeapRegion* curr = _head; 198 HeapRegion* last = NULL; 199 while (curr != NULL) { 200 if (!curr->is_young()) { 201 gclog_or_tty->print_cr("### YOUNG REGION " PTR_FORMAT "-" PTR_FORMAT " " 202 "incorrectly tagged (y: %d, surv: %d)", 203 p2i(curr->bottom()), p2i(curr->end()), 204 curr->is_young(), curr->is_survivor()); 205 ret = false; 206 } 207 ++length; 208 last = curr; 209 curr = curr->get_next_young_region(); 210 } 211 ret = ret && (length == _length); 212 213 if (!ret) { 214 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 215 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 216 length, _length); 217 } 218 219 return ret; 220 } 221 222 bool YoungList::check_list_empty(bool check_sample) { 223 bool ret = true; 224 225 if (_length != 0) { 226 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 227 _length); 228 ret = false; 229 } 230 if (check_sample && _last_sampled_rs_lengths != 0) { 231 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 232 ret = false; 233 } 234 if (_head != NULL) { 235 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 236 ret = false; 237 } 238 if (!ret) { 239 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 240 } 241 242 return ret; 243 } 244 245 void 246 YoungList::rs_length_sampling_init() { 247 _sampled_rs_lengths = 0; 248 _curr = _head; 249 } 250 251 bool 252 YoungList::rs_length_sampling_more() { 253 return _curr != NULL; 254 } 255 256 void 257 YoungList::rs_length_sampling_next() { 258 assert( _curr != NULL, "invariant" ); 259 size_t rs_length = _curr->rem_set()->occupied(); 260 261 _sampled_rs_lengths += rs_length; 262 263 // The current region may not yet have been added to the 264 // incremental collection set (it gets added when it is 265 // retired as the current allocation region). 266 if (_curr->in_collection_set()) { 267 // Update the collection set policy information for this region 268 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 269 } 270 271 _curr = _curr->get_next_young_region(); 272 if (_curr == NULL) { 273 _last_sampled_rs_lengths = _sampled_rs_lengths; 274 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 275 } 276 } 277 278 void 279 YoungList::reset_auxilary_lists() { 280 guarantee( is_empty(), "young list should be empty" ); 281 assert(check_list_well_formed(), "young list should be well formed"); 282 283 // Add survivor regions to SurvRateGroup. 284 _g1h->g1_policy()->note_start_adding_survivor_regions(); 285 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 286 287 int young_index_in_cset = 0; 288 for (HeapRegion* curr = _survivor_head; 289 curr != NULL; 290 curr = curr->get_next_young_region()) { 291 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 292 293 // The region is a non-empty survivor so let's add it to 294 // the incremental collection set for the next evacuation 295 // pause. 296 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 297 young_index_in_cset += 1; 298 } 299 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 300 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 301 302 _head = _survivor_head; 303 _length = _survivor_length; 304 if (_survivor_head != NULL) { 305 assert(_survivor_tail != NULL, "cause it shouldn't be"); 306 assert(_survivor_length > 0, "invariant"); 307 _survivor_tail->set_next_young_region(NULL); 308 } 309 310 // Don't clear the survivor list handles until the start of 311 // the next evacuation pause - we need it in order to re-tag 312 // the survivor regions from this evacuation pause as 'young' 313 // at the start of the next. 314 315 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 316 317 assert(check_list_well_formed(), "young list should be well formed"); 318 } 319 320 void YoungList::print() { 321 HeapRegion* lists[] = {_head, _survivor_head}; 322 const char* names[] = {"YOUNG", "SURVIVOR"}; 323 324 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) { 325 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 326 HeapRegion *curr = lists[list]; 327 if (curr == NULL) 328 gclog_or_tty->print_cr(" empty"); 329 while (curr != NULL) { 330 gclog_or_tty->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT ", N: " PTR_FORMAT ", age: %4d", 331 HR_FORMAT_PARAMS(curr), 332 p2i(curr->prev_top_at_mark_start()), 333 p2i(curr->next_top_at_mark_start()), 334 curr->age_in_surv_rate_group_cond()); 335 curr = curr->get_next_young_region(); 336 } 337 } 338 339 gclog_or_tty->cr(); 340 } 341 342 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 343 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 344 } 345 346 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 347 // The from card cache is not the memory that is actually committed. So we cannot 348 // take advantage of the zero_filled parameter. 349 reset_from_card_cache(start_idx, num_regions); 350 } 351 352 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 353 { 354 // Claim the right to put the region on the dirty cards region list 355 // by installing a self pointer. 356 HeapRegion* next = hr->get_next_dirty_cards_region(); 357 if (next == NULL) { 358 HeapRegion* res = (HeapRegion*) 359 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 360 NULL); 361 if (res == NULL) { 362 HeapRegion* head; 363 do { 364 // Put the region to the dirty cards region list. 365 head = _dirty_cards_region_list; 366 next = (HeapRegion*) 367 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 368 if (next == head) { 369 assert(hr->get_next_dirty_cards_region() == hr, 370 "hr->get_next_dirty_cards_region() != hr"); 371 if (next == NULL) { 372 // The last region in the list points to itself. 373 hr->set_next_dirty_cards_region(hr); 374 } else { 375 hr->set_next_dirty_cards_region(next); 376 } 377 } 378 } while (next != head); 379 } 380 } 381 } 382 383 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 384 { 385 HeapRegion* head; 386 HeapRegion* hr; 387 do { 388 head = _dirty_cards_region_list; 389 if (head == NULL) { 390 return NULL; 391 } 392 HeapRegion* new_head = head->get_next_dirty_cards_region(); 393 if (head == new_head) { 394 // The last region. 395 new_head = NULL; 396 } 397 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 398 head); 399 } while (hr != head); 400 assert(hr != NULL, "invariant"); 401 hr->set_next_dirty_cards_region(NULL); 402 return hr; 403 } 404 405 // Returns true if the reference points to an object that 406 // can move in an incremental collection. 407 bool G1CollectedHeap::is_scavengable(const void* p) { 408 HeapRegion* hr = heap_region_containing(p); 409 return !hr->is_pinned(); 410 } 411 412 // Private methods. 413 414 HeapRegion* 415 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 416 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 417 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 418 if (!_secondary_free_list.is_empty()) { 419 if (G1ConcRegionFreeingVerbose) { 420 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 421 "secondary_free_list has %u entries", 422 _secondary_free_list.length()); 423 } 424 // It looks as if there are free regions available on the 425 // secondary_free_list. Let's move them to the free_list and try 426 // again to allocate from it. 427 append_secondary_free_list(); 428 429 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " 430 "empty we should have moved at least one entry to the free_list"); 431 HeapRegion* res = _hrm.allocate_free_region(is_old); 432 if (G1ConcRegionFreeingVerbose) { 433 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 434 "allocated " HR_FORMAT " from secondary_free_list", 435 HR_FORMAT_PARAMS(res)); 436 } 437 return res; 438 } 439 440 // Wait here until we get notified either when (a) there are no 441 // more free regions coming or (b) some regions have been moved on 442 // the secondary_free_list. 443 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 444 } 445 446 if (G1ConcRegionFreeingVerbose) { 447 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 448 "could not allocate from secondary_free_list"); 449 } 450 return NULL; 451 } 452 453 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 454 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 455 "the only time we use this to allocate a humongous region is " 456 "when we are allocating a single humongous region"); 457 458 HeapRegion* res; 459 if (G1StressConcRegionFreeing) { 460 if (!_secondary_free_list.is_empty()) { 461 if (G1ConcRegionFreeingVerbose) { 462 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 463 "forced to look at the secondary_free_list"); 464 } 465 res = new_region_try_secondary_free_list(is_old); 466 if (res != NULL) { 467 return res; 468 } 469 } 470 } 471 472 res = _hrm.allocate_free_region(is_old); 473 474 if (res == NULL) { 475 if (G1ConcRegionFreeingVerbose) { 476 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 477 "res == NULL, trying the secondary_free_list"); 478 } 479 res = new_region_try_secondary_free_list(is_old); 480 } 481 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 482 // Currently, only attempts to allocate GC alloc regions set 483 // do_expand to true. So, we should only reach here during a 484 // safepoint. If this assumption changes we might have to 485 // reconsider the use of _expand_heap_after_alloc_failure. 486 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 487 488 ergo_verbose1(ErgoHeapSizing, 489 "attempt heap expansion", 490 ergo_format_reason("region allocation request failed") 491 ergo_format_byte("allocation request"), 492 word_size * HeapWordSize); 493 if (expand(word_size * HeapWordSize)) { 494 // Given that expand() succeeded in expanding the heap, and we 495 // always expand the heap by an amount aligned to the heap 496 // region size, the free list should in theory not be empty. 497 // In either case allocate_free_region() will check for NULL. 498 res = _hrm.allocate_free_region(is_old); 499 } else { 500 _expand_heap_after_alloc_failure = false; 501 } 502 } 503 return res; 504 } 505 506 HeapWord* 507 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 508 uint num_regions, 509 size_t word_size, 510 AllocationContext_t context) { 511 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 512 assert(is_humongous(word_size), "word_size should be humongous"); 513 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 514 515 // Index of last region in the series + 1. 516 uint last = first + num_regions; 517 518 // We need to initialize the region(s) we just discovered. This is 519 // a bit tricky given that it can happen concurrently with 520 // refinement threads refining cards on these regions and 521 // potentially wanting to refine the BOT as they are scanning 522 // those cards (this can happen shortly after a cleanup; see CR 523 // 6991377). So we have to set up the region(s) carefully and in 524 // a specific order. 525 526 // The word size sum of all the regions we will allocate. 527 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 528 assert(word_size <= word_size_sum, "sanity"); 529 530 // This will be the "starts humongous" region. 531 HeapRegion* first_hr = region_at(first); 532 // The header of the new object will be placed at the bottom of 533 // the first region. 534 HeapWord* new_obj = first_hr->bottom(); 535 // This will be the new end of the first region in the series that 536 // should also match the end of the last region in the series. 537 HeapWord* new_end = new_obj + word_size_sum; 538 // This will be the new top of the first region that will reflect 539 // this allocation. 540 HeapWord* new_top = new_obj + word_size; 541 542 // First, we need to zero the header of the space that we will be 543 // allocating. When we update top further down, some refinement 544 // threads might try to scan the region. By zeroing the header we 545 // ensure that any thread that will try to scan the region will 546 // come across the zero klass word and bail out. 547 // 548 // NOTE: It would not have been correct to have used 549 // CollectedHeap::fill_with_object() and make the space look like 550 // an int array. The thread that is doing the allocation will 551 // later update the object header to a potentially different array 552 // type and, for a very short period of time, the klass and length 553 // fields will be inconsistent. This could cause a refinement 554 // thread to calculate the object size incorrectly. 555 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 556 557 // We will set up the first region as "starts humongous". This 558 // will also update the BOT covering all the regions to reflect 559 // that there is a single object that starts at the bottom of the 560 // first region. 561 first_hr->set_starts_humongous(new_top, new_end); 562 first_hr->set_allocation_context(context); 563 // Then, if there are any, we will set up the "continues 564 // humongous" regions. 565 HeapRegion* hr = NULL; 566 for (uint i = first + 1; i < last; ++i) { 567 hr = region_at(i); 568 hr->set_continues_humongous(first_hr); 569 hr->set_allocation_context(context); 570 } 571 // If we have "continues humongous" regions (hr != NULL), then the 572 // end of the last one should match new_end. 573 assert(hr == NULL || hr->end() == new_end, "sanity"); 574 575 // Up to this point no concurrent thread would have been able to 576 // do any scanning on any region in this series. All the top 577 // fields still point to bottom, so the intersection between 578 // [bottom,top] and [card_start,card_end] will be empty. Before we 579 // update the top fields, we'll do a storestore to make sure that 580 // no thread sees the update to top before the zeroing of the 581 // object header and the BOT initialization. 582 OrderAccess::storestore(); 583 584 // Now that the BOT and the object header have been initialized, 585 // we can update top of the "starts humongous" region. 586 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 587 "new_top should be in this region"); 588 first_hr->set_top(new_top); 589 if (_hr_printer.is_active()) { 590 HeapWord* bottom = first_hr->bottom(); 591 HeapWord* end = first_hr->orig_end(); 592 if ((first + 1) == last) { 593 // the series has a single humongous region 594 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 595 } else { 596 // the series has more than one humongous regions 597 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 598 } 599 } 600 601 // Now, we will update the top fields of the "continues humongous" 602 // regions. The reason we need to do this is that, otherwise, 603 // these regions would look empty and this will confuse parts of 604 // G1. For example, the code that looks for a consecutive number 605 // of empty regions will consider them empty and try to 606 // re-allocate them. We can extend is_empty() to also include 607 // !is_continues_humongous(), but it is easier to just update the top 608 // fields here. The way we set top for all regions (i.e., top == 609 // end for all regions but the last one, top == new_top for the 610 // last one) is actually used when we will free up the humongous 611 // region in free_humongous_region(). 612 hr = NULL; 613 for (uint i = first + 1; i < last; ++i) { 614 hr = region_at(i); 615 if ((i + 1) == last) { 616 // last continues humongous region 617 assert(hr->bottom() < new_top && new_top <= hr->end(), 618 "new_top should fall on this region"); 619 hr->set_top(new_top); 620 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 621 } else { 622 // not last one 623 assert(new_top > hr->end(), "new_top should be above this region"); 624 hr->set_top(hr->end()); 625 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 626 } 627 } 628 // If we have continues humongous regions (hr != NULL), then the 629 // end of the last one should match new_end and its top should 630 // match new_top. 631 assert(hr == NULL || 632 (hr->end() == new_end && hr->top() == new_top), "sanity"); 633 check_bitmaps("Humongous Region Allocation", first_hr); 634 635 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 636 increase_used(first_hr->used()); 637 _humongous_set.add(first_hr); 638 639 return new_obj; 640 } 641 642 // If could fit into free regions w/o expansion, try. 643 // Otherwise, if can expand, do so. 644 // Otherwise, if using ex regions might help, try with ex given back. 645 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { 646 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 647 648 verify_region_sets_optional(); 649 650 uint first = G1_NO_HRM_INDEX; 651 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords); 652 653 if (obj_regions == 1) { 654 // Only one region to allocate, try to use a fast path by directly allocating 655 // from the free lists. Do not try to expand here, we will potentially do that 656 // later. 657 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 658 if (hr != NULL) { 659 first = hr->hrm_index(); 660 } 661 } else { 662 // We can't allocate humongous regions spanning more than one region while 663 // cleanupComplete() is running, since some of the regions we find to be 664 // empty might not yet be added to the free list. It is not straightforward 665 // to know in which list they are on so that we can remove them. We only 666 // need to do this if we need to allocate more than one region to satisfy the 667 // current humongous allocation request. If we are only allocating one region 668 // we use the one-region region allocation code (see above), that already 669 // potentially waits for regions from the secondary free list. 670 wait_while_free_regions_coming(); 671 append_secondary_free_list_if_not_empty_with_lock(); 672 673 // Policy: Try only empty regions (i.e. already committed first). Maybe we 674 // are lucky enough to find some. 675 first = _hrm.find_contiguous_only_empty(obj_regions); 676 if (first != G1_NO_HRM_INDEX) { 677 _hrm.allocate_free_regions_starting_at(first, obj_regions); 678 } 679 } 680 681 if (first == G1_NO_HRM_INDEX) { 682 // Policy: We could not find enough regions for the humongous object in the 683 // free list. Look through the heap to find a mix of free and uncommitted regions. 684 // If so, try expansion. 685 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 686 if (first != G1_NO_HRM_INDEX) { 687 // We found something. Make sure these regions are committed, i.e. expand 688 // the heap. Alternatively we could do a defragmentation GC. 689 ergo_verbose1(ErgoHeapSizing, 690 "attempt heap expansion", 691 ergo_format_reason("humongous allocation request failed") 692 ergo_format_byte("allocation request"), 693 word_size * HeapWordSize); 694 695 _hrm.expand_at(first, obj_regions); 696 g1_policy()->record_new_heap_size(num_regions()); 697 698 #ifdef ASSERT 699 for (uint i = first; i < first + obj_regions; ++i) { 700 HeapRegion* hr = region_at(i); 701 assert(hr->is_free(), "sanity"); 702 assert(hr->is_empty(), "sanity"); 703 assert(is_on_master_free_list(hr), "sanity"); 704 } 705 #endif 706 _hrm.allocate_free_regions_starting_at(first, obj_regions); 707 } else { 708 // Policy: Potentially trigger a defragmentation GC. 709 } 710 } 711 712 HeapWord* result = NULL; 713 if (first != G1_NO_HRM_INDEX) { 714 result = humongous_obj_allocate_initialize_regions(first, obj_regions, 715 word_size, context); 716 assert(result != NULL, "it should always return a valid result"); 717 718 // A successful humongous object allocation changes the used space 719 // information of the old generation so we need to recalculate the 720 // sizes and update the jstat counters here. 721 g1mm()->update_sizes(); 722 } 723 724 verify_region_sets_optional(); 725 726 return result; 727 } 728 729 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 730 assert_heap_not_locked_and_not_at_safepoint(); 731 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 732 733 uint dummy_gc_count_before; 734 uint dummy_gclocker_retry_count = 0; 735 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 736 } 737 738 HeapWord* 739 G1CollectedHeap::mem_allocate(size_t word_size, 740 bool* gc_overhead_limit_was_exceeded) { 741 assert_heap_not_locked_and_not_at_safepoint(); 742 743 // Loop until the allocation is satisfied, or unsatisfied after GC. 744 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 745 uint gc_count_before; 746 747 HeapWord* result = NULL; 748 if (!is_humongous(word_size)) { 749 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 750 } else { 751 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 752 } 753 if (result != NULL) { 754 return result; 755 } 756 757 // Create the garbage collection operation... 758 VM_G1CollectForAllocation op(gc_count_before, word_size); 759 op.set_allocation_context(AllocationContext::current()); 760 761 // ...and get the VM thread to execute it. 762 VMThread::execute(&op); 763 764 if (op.prologue_succeeded() && op.pause_succeeded()) { 765 // If the operation was successful we'll return the result even 766 // if it is NULL. If the allocation attempt failed immediately 767 // after a Full GC, it's unlikely we'll be able to allocate now. 768 HeapWord* result = op.result(); 769 if (result != NULL && !is_humongous(word_size)) { 770 // Allocations that take place on VM operations do not do any 771 // card dirtying and we have to do it here. We only have to do 772 // this for non-humongous allocations, though. 773 dirty_young_block(result, word_size); 774 } 775 return result; 776 } else { 777 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 778 return NULL; 779 } 780 assert(op.result() == NULL, 781 "the result should be NULL if the VM op did not succeed"); 782 } 783 784 // Give a warning if we seem to be looping forever. 785 if ((QueuedAllocationWarningCount > 0) && 786 (try_count % QueuedAllocationWarningCount == 0)) { 787 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 788 } 789 } 790 791 ShouldNotReachHere(); 792 return NULL; 793 } 794 795 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 796 AllocationContext_t context, 797 uint* gc_count_before_ret, 798 uint* gclocker_retry_count_ret) { 799 // Make sure you read the note in attempt_allocation_humongous(). 800 801 assert_heap_not_locked_and_not_at_safepoint(); 802 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 803 "be called for humongous allocation requests"); 804 805 // We should only get here after the first-level allocation attempt 806 // (attempt_allocation()) failed to allocate. 807 808 // We will loop until a) we manage to successfully perform the 809 // allocation or b) we successfully schedule a collection which 810 // fails to perform the allocation. b) is the only case when we'll 811 // return NULL. 812 HeapWord* result = NULL; 813 for (int try_count = 1; /* we'll return */; try_count += 1) { 814 bool should_try_gc; 815 uint gc_count_before; 816 817 { 818 MutexLockerEx x(Heap_lock); 819 result = _allocator->attempt_allocation_locked(word_size, context); 820 if (result != NULL) { 821 return result; 822 } 823 824 if (GC_locker::is_active_and_needs_gc()) { 825 if (g1_policy()->can_expand_young_list()) { 826 // No need for an ergo verbose message here, 827 // can_expand_young_list() does this when it returns true. 828 result = _allocator->attempt_allocation_force(word_size, context); 829 if (result != NULL) { 830 return result; 831 } 832 } 833 should_try_gc = false; 834 } else { 835 // The GCLocker may not be active but the GCLocker initiated 836 // GC may not yet have been performed (GCLocker::needs_gc() 837 // returns true). In this case we do not try this GC and 838 // wait until the GCLocker initiated GC is performed, and 839 // then retry the allocation. 840 if (GC_locker::needs_gc()) { 841 should_try_gc = false; 842 } else { 843 // Read the GC count while still holding the Heap_lock. 844 gc_count_before = total_collections(); 845 should_try_gc = true; 846 } 847 } 848 } 849 850 if (should_try_gc) { 851 bool succeeded; 852 result = do_collection_pause(word_size, gc_count_before, &succeeded, 853 GCCause::_g1_inc_collection_pause); 854 if (result != NULL) { 855 assert(succeeded, "only way to get back a non-NULL result"); 856 return result; 857 } 858 859 if (succeeded) { 860 // If we get here we successfully scheduled a collection which 861 // failed to allocate. No point in trying to allocate 862 // further. We'll just return NULL. 863 MutexLockerEx x(Heap_lock); 864 *gc_count_before_ret = total_collections(); 865 return NULL; 866 } 867 } else { 868 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 869 MutexLockerEx x(Heap_lock); 870 *gc_count_before_ret = total_collections(); 871 return NULL; 872 } 873 // The GCLocker is either active or the GCLocker initiated 874 // GC has not yet been performed. Stall until it is and 875 // then retry the allocation. 876 GC_locker::stall_until_clear(); 877 (*gclocker_retry_count_ret) += 1; 878 } 879 880 // We can reach here if we were unsuccessful in scheduling a 881 // collection (because another thread beat us to it) or if we were 882 // stalled due to the GC locker. In either can we should retry the 883 // allocation attempt in case another thread successfully 884 // performed a collection and reclaimed enough space. We do the 885 // first attempt (without holding the Heap_lock) here and the 886 // follow-on attempt will be at the start of the next loop 887 // iteration (after taking the Heap_lock). 888 result = _allocator->attempt_allocation(word_size, context); 889 if (result != NULL) { 890 return result; 891 } 892 893 // Give a warning if we seem to be looping forever. 894 if ((QueuedAllocationWarningCount > 0) && 895 (try_count % QueuedAllocationWarningCount == 0)) { 896 warning("G1CollectedHeap::attempt_allocation_slow() " 897 "retries %d times", try_count); 898 } 899 } 900 901 ShouldNotReachHere(); 902 return NULL; 903 } 904 905 void G1CollectedHeap::begin_archive_alloc_range() { 906 assert_at_safepoint(true /* should_be_vm_thread */); 907 if (_archive_allocator == NULL) { 908 _archive_allocator = G1ArchiveAllocator::create_allocator(this); 909 } 910 } 911 912 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 913 // Allocations in archive regions cannot be of a size that would be considered 914 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 915 // may be different at archive-restore time. 916 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 917 } 918 919 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 920 assert_at_safepoint(true /* should_be_vm_thread */); 921 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 922 if (is_archive_alloc_too_large(word_size)) { 923 return NULL; 924 } 925 return _archive_allocator->archive_mem_allocate(word_size); 926 } 927 928 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 929 size_t end_alignment_in_bytes) { 930 assert_at_safepoint(true /* should_be_vm_thread */); 931 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 932 933 // Call complete_archive to do the real work, filling in the MemRegion 934 // array with the archive regions. 935 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 936 delete _archive_allocator; 937 _archive_allocator = NULL; 938 } 939 940 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 941 assert(ranges != NULL, "MemRegion array NULL"); 942 assert(count != 0, "No MemRegions provided"); 943 MemRegion reserved = _hrm.reserved(); 944 for (size_t i = 0; i < count; i++) { 945 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 946 return false; 947 } 948 } 949 return true; 950 } 951 952 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) { 953 assert(!is_init_completed(), "Expect to be called at JVM init time"); 954 assert(ranges != NULL, "MemRegion array NULL"); 955 assert(count != 0, "No MemRegions provided"); 956 MutexLockerEx x(Heap_lock); 957 958 MemRegion reserved = _hrm.reserved(); 959 HeapWord* prev_last_addr = NULL; 960 HeapRegion* prev_last_region = NULL; 961 962 // Temporarily disable pretouching of heap pages. This interface is used 963 // when mmap'ing archived heap data in, so pre-touching is wasted. 964 FlagSetting fs(AlwaysPreTouch, false); 965 966 // Enable archive object checking in G1MarkSweep. We have to let it know 967 // about each archive range, so that objects in those ranges aren't marked. 968 G1MarkSweep::enable_archive_object_check(); 969 970 // For each specified MemRegion range, allocate the corresponding G1 971 // regions and mark them as archive regions. We expect the ranges in 972 // ascending starting address order, without overlap. 973 for (size_t i = 0; i < count; i++) { 974 MemRegion curr_range = ranges[i]; 975 HeapWord* start_address = curr_range.start(); 976 size_t word_size = curr_range.word_size(); 977 HeapWord* last_address = curr_range.last(); 978 size_t commits = 0; 979 980 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 981 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 982 p2i(start_address), p2i(last_address))); 983 guarantee(start_address > prev_last_addr, 984 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 985 p2i(start_address), p2i(prev_last_addr))); 986 prev_last_addr = last_address; 987 988 // Check for ranges that start in the same G1 region in which the previous 989 // range ended, and adjust the start address so we don't try to allocate 990 // the same region again. If the current range is entirely within that 991 // region, skip it, just adjusting the recorded top. 992 HeapRegion* start_region = _hrm.addr_to_region(start_address); 993 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 994 start_address = start_region->end(); 995 if (start_address > last_address) { 996 increase_used(word_size * HeapWordSize); 997 start_region->set_top(last_address + 1); 998 continue; 999 } 1000 start_region->set_top(start_address); 1001 curr_range = MemRegion(start_address, last_address + 1); 1002 start_region = _hrm.addr_to_region(start_address); 1003 } 1004 1005 // Perform the actual region allocation, exiting if it fails. 1006 // Then note how much new space we have allocated. 1007 if (!_hrm.allocate_containing_regions(curr_range, &commits)) { 1008 return false; 1009 } 1010 increase_used(word_size * HeapWordSize); 1011 if (commits != 0) { 1012 ergo_verbose1(ErgoHeapSizing, 1013 "attempt heap expansion", 1014 ergo_format_reason("allocate archive regions") 1015 ergo_format_byte("total size"), 1016 HeapRegion::GrainWords * HeapWordSize * commits); 1017 } 1018 1019 // Mark each G1 region touched by the range as archive, add it to the old set, 1020 // and set the allocation context and top. 1021 HeapRegion* curr_region = _hrm.addr_to_region(start_address); 1022 HeapRegion* last_region = _hrm.addr_to_region(last_address); 1023 prev_last_region = last_region; 1024 1025 while (curr_region != NULL) { 1026 assert(curr_region->is_empty() && !curr_region->is_pinned(), 1027 err_msg("Region already in use (index %u)", curr_region->hrm_index())); 1028 _hr_printer.alloc(curr_region, G1HRPrinter::Archive); 1029 curr_region->set_allocation_context(AllocationContext::system()); 1030 curr_region->set_archive(); 1031 _old_set.add(curr_region); 1032 if (curr_region != last_region) { 1033 curr_region->set_top(curr_region->end()); 1034 curr_region = _hrm.next_region_in_heap(curr_region); 1035 } else { 1036 curr_region->set_top(last_address + 1); 1037 curr_region = NULL; 1038 } 1039 } 1040 1041 // Notify mark-sweep of the archive range. 1042 G1MarkSweep::set_range_archive(curr_range, true); 1043 } 1044 return true; 1045 } 1046 1047 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 1048 assert(!is_init_completed(), "Expect to be called at JVM init time"); 1049 assert(ranges != NULL, "MemRegion array NULL"); 1050 assert(count != 0, "No MemRegions provided"); 1051 MemRegion reserved = _hrm.reserved(); 1052 HeapWord *prev_last_addr = NULL; 1053 HeapRegion* prev_last_region = NULL; 1054 1055 // For each MemRegion, create filler objects, if needed, in the G1 regions 1056 // that contain the address range. The address range actually within the 1057 // MemRegion will not be modified. That is assumed to have been initialized 1058 // elsewhere, probably via an mmap of archived heap data. 1059 MutexLockerEx x(Heap_lock); 1060 for (size_t i = 0; i < count; i++) { 1061 HeapWord* start_address = ranges[i].start(); 1062 HeapWord* last_address = ranges[i].last(); 1063 1064 assert(reserved.contains(start_address) && reserved.contains(last_address), 1065 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 1066 p2i(start_address), p2i(last_address))); 1067 assert(start_address > prev_last_addr, 1068 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 1069 p2i(start_address), p2i(prev_last_addr))); 1070 1071 HeapRegion* start_region = _hrm.addr_to_region(start_address); 1072 HeapRegion* last_region = _hrm.addr_to_region(last_address); 1073 HeapWord* bottom_address = start_region->bottom(); 1074 1075 // Check for a range beginning in the same region in which the 1076 // previous one ended. 1077 if (start_region == prev_last_region) { 1078 bottom_address = prev_last_addr + 1; 1079 } 1080 1081 // Verify that the regions were all marked as archive regions by 1082 // alloc_archive_regions. 1083 HeapRegion* curr_region = start_region; 1084 while (curr_region != NULL) { 1085 guarantee(curr_region->is_archive(), 1086 err_msg("Expected archive region at index %u", curr_region->hrm_index())); 1087 if (curr_region != last_region) { 1088 curr_region = _hrm.next_region_in_heap(curr_region); 1089 } else { 1090 curr_region = NULL; 1091 } 1092 } 1093 1094 prev_last_addr = last_address; 1095 prev_last_region = last_region; 1096 1097 // Fill the memory below the allocated range with dummy object(s), 1098 // if the region bottom does not match the range start, or if the previous 1099 // range ended within the same G1 region, and there is a gap. 1100 if (start_address != bottom_address) { 1101 size_t fill_size = pointer_delta(start_address, bottom_address); 1102 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 1103 increase_used(fill_size * HeapWordSize); 1104 } 1105 } 1106 } 1107 1108 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size, 1109 uint* gc_count_before_ret, 1110 uint* gclocker_retry_count_ret) { 1111 assert_heap_not_locked_and_not_at_safepoint(); 1112 assert(!is_humongous(word_size), "attempt_allocation() should not " 1113 "be called for humongous allocation requests"); 1114 1115 AllocationContext_t context = AllocationContext::current(); 1116 HeapWord* result = _allocator->attempt_allocation(word_size, context); 1117 1118 if (result == NULL) { 1119 result = attempt_allocation_slow(word_size, 1120 context, 1121 gc_count_before_ret, 1122 gclocker_retry_count_ret); 1123 } 1124 assert_heap_not_locked(); 1125 if (result != NULL) { 1126 dirty_young_block(result, word_size); 1127 } 1128 return result; 1129 } 1130 1131 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 1132 assert(!is_init_completed(), "Expect to be called at JVM init time"); 1133 assert(ranges != NULL, "MemRegion array NULL"); 1134 assert(count != 0, "No MemRegions provided"); 1135 MemRegion reserved = _hrm.reserved(); 1136 HeapWord* prev_last_addr = NULL; 1137 HeapRegion* prev_last_region = NULL; 1138 size_t size_used = 0; 1139 size_t uncommitted_regions = 0; 1140 1141 // For each Memregion, free the G1 regions that constitute it, and 1142 // notify mark-sweep that the range is no longer to be considered 'archive.' 1143 MutexLockerEx x(Heap_lock); 1144 for (size_t i = 0; i < count; i++) { 1145 HeapWord* start_address = ranges[i].start(); 1146 HeapWord* last_address = ranges[i].last(); 1147 1148 assert(reserved.contains(start_address) && reserved.contains(last_address), 1149 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 1150 p2i(start_address), p2i(last_address))); 1151 assert(start_address > prev_last_addr, 1152 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 1153 p2i(start_address), p2i(prev_last_addr))); 1154 size_used += ranges[i].byte_size(); 1155 prev_last_addr = last_address; 1156 1157 HeapRegion* start_region = _hrm.addr_to_region(start_address); 1158 HeapRegion* last_region = _hrm.addr_to_region(last_address); 1159 1160 // Check for ranges that start in the same G1 region in which the previous 1161 // range ended, and adjust the start address so we don't try to free 1162 // the same region again. If the current range is entirely within that 1163 // region, skip it. 1164 if (start_region == prev_last_region) { 1165 start_address = start_region->end(); 1166 if (start_address > last_address) { 1167 continue; 1168 } 1169 start_region = _hrm.addr_to_region(start_address); 1170 } 1171 prev_last_region = last_region; 1172 1173 // After verifying that each region was marked as an archive region by 1174 // alloc_archive_regions, set it free and empty and uncommit it. 1175 HeapRegion* curr_region = start_region; 1176 while (curr_region != NULL) { 1177 guarantee(curr_region->is_archive(), 1178 err_msg("Expected archive region at index %u", curr_region->hrm_index())); 1179 uint curr_index = curr_region->hrm_index(); 1180 _old_set.remove(curr_region); 1181 curr_region->set_free(); 1182 curr_region->set_top(curr_region->bottom()); 1183 if (curr_region != last_region) { 1184 curr_region = _hrm.next_region_in_heap(curr_region); 1185 } else { 1186 curr_region = NULL; 1187 } 1188 _hrm.shrink_at(curr_index, 1); 1189 uncommitted_regions++; 1190 } 1191 1192 // Notify mark-sweep that this is no longer an archive range. 1193 G1MarkSweep::set_range_archive(ranges[i], false); 1194 } 1195 1196 if (uncommitted_regions != 0) { 1197 ergo_verbose1(ErgoHeapSizing, 1198 "attempt heap shrinking", 1199 ergo_format_reason("uncommitted archive regions") 1200 ergo_format_byte("total size"), 1201 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 1202 } 1203 decrease_used(size_used); 1204 } 1205 1206 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 1207 uint* gc_count_before_ret, 1208 uint* gclocker_retry_count_ret) { 1209 // The structure of this method has a lot of similarities to 1210 // attempt_allocation_slow(). The reason these two were not merged 1211 // into a single one is that such a method would require several "if 1212 // allocation is not humongous do this, otherwise do that" 1213 // conditional paths which would obscure its flow. In fact, an early 1214 // version of this code did use a unified method which was harder to 1215 // follow and, as a result, it had subtle bugs that were hard to 1216 // track down. So keeping these two methods separate allows each to 1217 // be more readable. It will be good to keep these two in sync as 1218 // much as possible. 1219 1220 assert_heap_not_locked_and_not_at_safepoint(); 1221 assert(is_humongous(word_size), "attempt_allocation_humongous() " 1222 "should only be called for humongous allocations"); 1223 1224 // Humongous objects can exhaust the heap quickly, so we should check if we 1225 // need to start a marking cycle at each humongous object allocation. We do 1226 // the check before we do the actual allocation. The reason for doing it 1227 // before the allocation is that we avoid having to keep track of the newly 1228 // allocated memory while we do a GC. 1229 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1230 word_size)) { 1231 collect(GCCause::_g1_humongous_allocation); 1232 } 1233 1234 // We will loop until a) we manage to successfully perform the 1235 // allocation or b) we successfully schedule a collection which 1236 // fails to perform the allocation. b) is the only case when we'll 1237 // return NULL. 1238 HeapWord* result = NULL; 1239 for (int try_count = 1; /* we'll return */; try_count += 1) { 1240 bool should_try_gc; 1241 uint gc_count_before; 1242 1243 { 1244 MutexLockerEx x(Heap_lock); 1245 1246 // Given that humongous objects are not allocated in young 1247 // regions, we'll first try to do the allocation without doing a 1248 // collection hoping that there's enough space in the heap. 1249 result = humongous_obj_allocate(word_size, AllocationContext::current()); 1250 if (result != NULL) { 1251 return result; 1252 } 1253 1254 if (GC_locker::is_active_and_needs_gc()) { 1255 should_try_gc = false; 1256 } else { 1257 // The GCLocker may not be active but the GCLocker initiated 1258 // GC may not yet have been performed (GCLocker::needs_gc() 1259 // returns true). In this case we do not try this GC and 1260 // wait until the GCLocker initiated GC is performed, and 1261 // then retry the allocation. 1262 if (GC_locker::needs_gc()) { 1263 should_try_gc = false; 1264 } else { 1265 // Read the GC count while still holding the Heap_lock. 1266 gc_count_before = total_collections(); 1267 should_try_gc = true; 1268 } 1269 } 1270 } 1271 1272 if (should_try_gc) { 1273 // If we failed to allocate the humongous object, we should try to 1274 // do a collection pause (if we're allowed) in case it reclaims 1275 // enough space for the allocation to succeed after the pause. 1276 1277 bool succeeded; 1278 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1279 GCCause::_g1_humongous_allocation); 1280 if (result != NULL) { 1281 assert(succeeded, "only way to get back a non-NULL result"); 1282 return result; 1283 } 1284 1285 if (succeeded) { 1286 // If we get here we successfully scheduled a collection which 1287 // failed to allocate. No point in trying to allocate 1288 // further. We'll just return NULL. 1289 MutexLockerEx x(Heap_lock); 1290 *gc_count_before_ret = total_collections(); 1291 return NULL; 1292 } 1293 } else { 1294 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1295 MutexLockerEx x(Heap_lock); 1296 *gc_count_before_ret = total_collections(); 1297 return NULL; 1298 } 1299 // The GCLocker is either active or the GCLocker initiated 1300 // GC has not yet been performed. Stall until it is and 1301 // then retry the allocation. 1302 GC_locker::stall_until_clear(); 1303 (*gclocker_retry_count_ret) += 1; 1304 } 1305 1306 // We can reach here if we were unsuccessful in scheduling a 1307 // collection (because another thread beat us to it) or if we were 1308 // stalled due to the GC locker. In either can we should retry the 1309 // allocation attempt in case another thread successfully 1310 // performed a collection and reclaimed enough space. Give a 1311 // warning if we seem to be looping forever. 1312 1313 if ((QueuedAllocationWarningCount > 0) && 1314 (try_count % QueuedAllocationWarningCount == 0)) { 1315 warning("G1CollectedHeap::attempt_allocation_humongous() " 1316 "retries %d times", try_count); 1317 } 1318 } 1319 1320 ShouldNotReachHere(); 1321 return NULL; 1322 } 1323 1324 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1325 AllocationContext_t context, 1326 bool expect_null_mutator_alloc_region) { 1327 assert_at_safepoint(true /* should_be_vm_thread */); 1328 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region, 1329 "the current alloc region was unexpectedly found to be non-NULL"); 1330 1331 if (!is_humongous(word_size)) { 1332 return _allocator->attempt_allocation_locked(word_size, context); 1333 } else { 1334 HeapWord* result = humongous_obj_allocate(word_size, context); 1335 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1336 collector_state()->set_initiate_conc_mark_if_possible(true); 1337 } 1338 return result; 1339 } 1340 1341 ShouldNotReachHere(); 1342 } 1343 1344 class PostMCRemSetClearClosure: public HeapRegionClosure { 1345 G1CollectedHeap* _g1h; 1346 ModRefBarrierSet* _mr_bs; 1347 public: 1348 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1349 _g1h(g1h), _mr_bs(mr_bs) {} 1350 1351 bool doHeapRegion(HeapRegion* r) { 1352 HeapRegionRemSet* hrrs = r->rem_set(); 1353 1354 if (r->is_continues_humongous()) { 1355 // We'll assert that the strong code root list and RSet is empty 1356 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1357 assert(hrrs->occupied() == 0, "RSet should be empty"); 1358 return false; 1359 } 1360 1361 _g1h->reset_gc_time_stamps(r); 1362 hrrs->clear(); 1363 // You might think here that we could clear just the cards 1364 // corresponding to the used region. But no: if we leave a dirty card 1365 // in a region we might allocate into, then it would prevent that card 1366 // from being enqueued, and cause it to be missed. 1367 // Re: the performance cost: we shouldn't be doing full GC anyway! 1368 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1369 1370 return false; 1371 } 1372 }; 1373 1374 void G1CollectedHeap::clear_rsets_post_compaction() { 1375 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1376 heap_region_iterate(&rs_clear); 1377 } 1378 1379 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1380 G1CollectedHeap* _g1h; 1381 UpdateRSOopClosure _cl; 1382 public: 1383 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) : 1384 _cl(g1->g1_rem_set(), worker_i), 1385 _g1h(g1) 1386 { } 1387 1388 bool doHeapRegion(HeapRegion* r) { 1389 if (!r->is_continues_humongous()) { 1390 _cl.set_from(r); 1391 r->oop_iterate(&_cl); 1392 } 1393 return false; 1394 } 1395 }; 1396 1397 class ParRebuildRSTask: public AbstractGangTask { 1398 G1CollectedHeap* _g1; 1399 HeapRegionClaimer _hrclaimer; 1400 1401 public: 1402 ParRebuildRSTask(G1CollectedHeap* g1) : 1403 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {} 1404 1405 void work(uint worker_id) { 1406 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1407 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer); 1408 } 1409 }; 1410 1411 class PostCompactionPrinterClosure: public HeapRegionClosure { 1412 private: 1413 G1HRPrinter* _hr_printer; 1414 public: 1415 bool doHeapRegion(HeapRegion* hr) { 1416 assert(!hr->is_young(), "not expecting to find young regions"); 1417 if (hr->is_free()) { 1418 // We only generate output for non-empty regions. 1419 } else if (hr->is_starts_humongous()) { 1420 if (hr->region_num() == 1) { 1421 // single humongous region 1422 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1423 } else { 1424 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1425 } 1426 } else if (hr->is_continues_humongous()) { 1427 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1428 } else if (hr->is_archive()) { 1429 _hr_printer->post_compaction(hr, G1HRPrinter::Archive); 1430 } else if (hr->is_old()) { 1431 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1432 } else { 1433 ShouldNotReachHere(); 1434 } 1435 return false; 1436 } 1437 1438 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1439 : _hr_printer(hr_printer) { } 1440 }; 1441 1442 void G1CollectedHeap::print_hrm_post_compaction() { 1443 PostCompactionPrinterClosure cl(hr_printer()); 1444 heap_region_iterate(&cl); 1445 } 1446 1447 bool G1CollectedHeap::do_collection(bool explicit_gc, 1448 bool clear_all_soft_refs, 1449 size_t word_size) { 1450 assert_at_safepoint(true /* should_be_vm_thread */); 1451 1452 if (GC_locker::check_active_before_gc()) { 1453 return false; 1454 } 1455 1456 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1457 gc_timer->register_gc_start(); 1458 1459 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1460 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1461 1462 SvcGCMarker sgcm(SvcGCMarker::FULL); 1463 ResourceMark rm; 1464 1465 G1Log::update_level(); 1466 print_heap_before_gc(); 1467 trace_heap_before_gc(gc_tracer); 1468 1469 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1470 1471 verify_region_sets_optional(); 1472 1473 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1474 collector_policy()->should_clear_all_soft_refs(); 1475 1476 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1477 1478 { 1479 IsGCActiveMark x; 1480 1481 // Timing 1482 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1483 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1484 1485 { 1486 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id()); 1487 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1488 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1489 1490 g1_policy()->record_full_collection_start(); 1491 1492 // Note: When we have a more flexible GC logging framework that 1493 // allows us to add optional attributes to a GC log record we 1494 // could consider timing and reporting how long we wait in the 1495 // following two methods. 1496 wait_while_free_regions_coming(); 1497 // If we start the compaction before the CM threads finish 1498 // scanning the root regions we might trip them over as we'll 1499 // be moving objects / updating references. So let's wait until 1500 // they are done. By telling them to abort, they should complete 1501 // early. 1502 _cm->root_regions()->abort(); 1503 _cm->root_regions()->wait_until_scan_finished(); 1504 append_secondary_free_list_if_not_empty_with_lock(); 1505 1506 gc_prologue(true); 1507 increment_total_collections(true /* full gc */); 1508 increment_old_marking_cycles_started(); 1509 1510 assert(used() == recalculate_used(), "Should be equal"); 1511 1512 verify_before_gc(); 1513 1514 check_bitmaps("Full GC Start"); 1515 pre_full_gc_dump(gc_timer); 1516 1517 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1518 1519 // Disable discovery and empty the discovered lists 1520 // for the CM ref processor. 1521 ref_processor_cm()->disable_discovery(); 1522 ref_processor_cm()->abandon_partial_discovery(); 1523 ref_processor_cm()->verify_no_references_recorded(); 1524 1525 // Abandon current iterations of concurrent marking and concurrent 1526 // refinement, if any are in progress. We have to do this before 1527 // wait_until_scan_finished() below. 1528 concurrent_mark()->abort(); 1529 1530 // Make sure we'll choose a new allocation region afterwards. 1531 _allocator->release_mutator_alloc_region(); 1532 _allocator->abandon_gc_alloc_regions(); 1533 g1_rem_set()->cleanupHRRS(); 1534 1535 // We should call this after we retire any currently active alloc 1536 // regions so that all the ALLOC / RETIRE events are generated 1537 // before the start GC event. 1538 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1539 1540 // We may have added regions to the current incremental collection 1541 // set between the last GC or pause and now. We need to clear the 1542 // incremental collection set and then start rebuilding it afresh 1543 // after this full GC. 1544 abandon_collection_set(g1_policy()->inc_cset_head()); 1545 g1_policy()->clear_incremental_cset(); 1546 g1_policy()->stop_incremental_cset_building(); 1547 1548 tear_down_region_sets(false /* free_list_only */); 1549 collector_state()->set_gcs_are_young(true); 1550 1551 // See the comments in g1CollectedHeap.hpp and 1552 // G1CollectedHeap::ref_processing_init() about 1553 // how reference processing currently works in G1. 1554 1555 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1556 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1557 1558 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1559 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1560 1561 ref_processor_stw()->enable_discovery(); 1562 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1563 1564 // Do collection work 1565 { 1566 HandleMark hm; // Discard invalid handles created during gc 1567 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1568 } 1569 1570 assert(num_free_regions() == 0, "we should not have added any free regions"); 1571 rebuild_region_sets(false /* free_list_only */); 1572 1573 // Enqueue any discovered reference objects that have 1574 // not been removed from the discovered lists. 1575 ref_processor_stw()->enqueue_discovered_references(); 1576 1577 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1578 1579 MemoryService::track_memory_usage(); 1580 1581 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1582 ref_processor_stw()->verify_no_references_recorded(); 1583 1584 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1585 ClassLoaderDataGraph::purge(); 1586 MetaspaceAux::verify_metrics(); 1587 1588 // Note: since we've just done a full GC, concurrent 1589 // marking is no longer active. Therefore we need not 1590 // re-enable reference discovery for the CM ref processor. 1591 // That will be done at the start of the next marking cycle. 1592 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1593 ref_processor_cm()->verify_no_references_recorded(); 1594 1595 reset_gc_time_stamp(); 1596 // Since everything potentially moved, we will clear all remembered 1597 // sets, and clear all cards. Later we will rebuild remembered 1598 // sets. We will also reset the GC time stamps of the regions. 1599 clear_rsets_post_compaction(); 1600 check_gc_time_stamps(); 1601 1602 // Resize the heap if necessary. 1603 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1604 1605 if (_hr_printer.is_active()) { 1606 // We should do this after we potentially resize the heap so 1607 // that all the COMMIT / UNCOMMIT events are generated before 1608 // the end GC event. 1609 1610 print_hrm_post_compaction(); 1611 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1612 } 1613 1614 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1615 if (hot_card_cache->use_cache()) { 1616 hot_card_cache->reset_card_counts(); 1617 hot_card_cache->reset_hot_cache(); 1618 } 1619 1620 // Rebuild remembered sets of all regions. 1621 uint n_workers = 1622 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1623 workers()->active_workers(), 1624 Threads::number_of_non_daemon_threads()); 1625 workers()->set_active_workers(n_workers); 1626 1627 ParRebuildRSTask rebuild_rs_task(this); 1628 workers()->run_task(&rebuild_rs_task); 1629 1630 // Rebuild the strong code root lists for each region 1631 rebuild_strong_code_roots(); 1632 1633 if (true) { // FIXME 1634 MetaspaceGC::compute_new_size(); 1635 } 1636 1637 #ifdef TRACESPINNING 1638 ParallelTaskTerminator::print_termination_counts(); 1639 #endif 1640 1641 // Discard all rset updates 1642 JavaThread::dirty_card_queue_set().abandon_logs(); 1643 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1644 1645 _young_list->reset_sampled_info(); 1646 // At this point there should be no regions in the 1647 // entire heap tagged as young. 1648 assert(check_young_list_empty(true /* check_heap */), 1649 "young list should be empty at this point"); 1650 1651 // Update the number of full collections that have been completed. 1652 increment_old_marking_cycles_completed(false /* concurrent */); 1653 1654 _hrm.verify_optional(); 1655 verify_region_sets_optional(); 1656 1657 verify_after_gc(); 1658 1659 // Clear the previous marking bitmap, if needed for bitmap verification. 1660 // Note we cannot do this when we clear the next marking bitmap in 1661 // ConcurrentMark::abort() above since VerifyDuringGC verifies the 1662 // objects marked during a full GC against the previous bitmap. 1663 // But we need to clear it before calling check_bitmaps below since 1664 // the full GC has compacted objects and updated TAMS but not updated 1665 // the prev bitmap. 1666 if (G1VerifyBitmaps) { 1667 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); 1668 } 1669 check_bitmaps("Full GC End"); 1670 1671 // Start a new incremental collection set for the next pause 1672 assert(g1_policy()->collection_set() == NULL, "must be"); 1673 g1_policy()->start_incremental_cset_building(); 1674 1675 clear_cset_fast_test(); 1676 1677 _allocator->init_mutator_alloc_region(); 1678 1679 g1_policy()->record_full_collection_end(); 1680 1681 if (G1Log::fine()) { 1682 g1_policy()->print_heap_transition(); 1683 } 1684 1685 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1686 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1687 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1688 // before any GC notifications are raised. 1689 g1mm()->update_sizes(); 1690 1691 gc_epilogue(true); 1692 } 1693 1694 if (G1Log::finer()) { 1695 g1_policy()->print_detailed_heap_transition(true /* full */); 1696 } 1697 1698 print_heap_after_gc(); 1699 trace_heap_after_gc(gc_tracer); 1700 1701 post_full_gc_dump(gc_timer); 1702 1703 gc_timer->register_gc_end(); 1704 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1705 } 1706 1707 return true; 1708 } 1709 1710 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1711 // do_collection() will return whether it succeeded in performing 1712 // the GC. Currently, there is no facility on the 1713 // do_full_collection() API to notify the caller than the collection 1714 // did not succeed (e.g., because it was locked out by the GC 1715 // locker). So, right now, we'll ignore the return value. 1716 bool dummy = do_collection(true, /* explicit_gc */ 1717 clear_all_soft_refs, 1718 0 /* word_size */); 1719 } 1720 1721 // This code is mostly copied from TenuredGeneration. 1722 void 1723 G1CollectedHeap:: 1724 resize_if_necessary_after_full_collection(size_t word_size) { 1725 // Include the current allocation, if any, and bytes that will be 1726 // pre-allocated to support collections, as "used". 1727 const size_t used_after_gc = used(); 1728 const size_t capacity_after_gc = capacity(); 1729 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1730 1731 // This is enforced in arguments.cpp. 1732 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1733 "otherwise the code below doesn't make sense"); 1734 1735 // We don't have floating point command-line arguments 1736 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1737 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1738 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1739 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1740 1741 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1742 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1743 1744 // We have to be careful here as these two calculations can overflow 1745 // 32-bit size_t's. 1746 double used_after_gc_d = (double) used_after_gc; 1747 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1748 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1749 1750 // Let's make sure that they are both under the max heap size, which 1751 // by default will make them fit into a size_t. 1752 double desired_capacity_upper_bound = (double) max_heap_size; 1753 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1754 desired_capacity_upper_bound); 1755 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1756 desired_capacity_upper_bound); 1757 1758 // We can now safely turn them into size_t's. 1759 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1760 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1761 1762 // This assert only makes sense here, before we adjust them 1763 // with respect to the min and max heap size. 1764 assert(minimum_desired_capacity <= maximum_desired_capacity, 1765 err_msg("minimum_desired_capacity = " SIZE_FORMAT ", " 1766 "maximum_desired_capacity = " SIZE_FORMAT, 1767 minimum_desired_capacity, maximum_desired_capacity)); 1768 1769 // Should not be greater than the heap max size. No need to adjust 1770 // it with respect to the heap min size as it's a lower bound (i.e., 1771 // we'll try to make the capacity larger than it, not smaller). 1772 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1773 // Should not be less than the heap min size. No need to adjust it 1774 // with respect to the heap max size as it's an upper bound (i.e., 1775 // we'll try to make the capacity smaller than it, not greater). 1776 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1777 1778 if (capacity_after_gc < minimum_desired_capacity) { 1779 // Don't expand unless it's significant 1780 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1781 ergo_verbose4(ErgoHeapSizing, 1782 "attempt heap expansion", 1783 ergo_format_reason("capacity lower than " 1784 "min desired capacity after Full GC") 1785 ergo_format_byte("capacity") 1786 ergo_format_byte("occupancy") 1787 ergo_format_byte_perc("min desired capacity"), 1788 capacity_after_gc, used_after_gc, 1789 minimum_desired_capacity, (double) MinHeapFreeRatio); 1790 expand(expand_bytes); 1791 1792 // No expansion, now see if we want to shrink 1793 } else if (capacity_after_gc > maximum_desired_capacity) { 1794 // Capacity too large, compute shrinking size 1795 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1796 ergo_verbose4(ErgoHeapSizing, 1797 "attempt heap shrinking", 1798 ergo_format_reason("capacity higher than " 1799 "max desired capacity after Full GC") 1800 ergo_format_byte("capacity") 1801 ergo_format_byte("occupancy") 1802 ergo_format_byte_perc("max desired capacity"), 1803 capacity_after_gc, used_after_gc, 1804 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1805 shrink(shrink_bytes); 1806 } 1807 } 1808 1809 1810 HeapWord* 1811 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1812 AllocationContext_t context, 1813 bool* succeeded) { 1814 assert_at_safepoint(true /* should_be_vm_thread */); 1815 1816 *succeeded = true; 1817 // Let's attempt the allocation first. 1818 HeapWord* result = 1819 attempt_allocation_at_safepoint(word_size, 1820 context, 1821 false /* expect_null_mutator_alloc_region */); 1822 if (result != NULL) { 1823 assert(*succeeded, "sanity"); 1824 return result; 1825 } 1826 1827 // In a G1 heap, we're supposed to keep allocation from failing by 1828 // incremental pauses. Therefore, at least for now, we'll favor 1829 // expansion over collection. (This might change in the future if we can 1830 // do something smarter than full collection to satisfy a failed alloc.) 1831 result = expand_and_allocate(word_size, context); 1832 if (result != NULL) { 1833 assert(*succeeded, "sanity"); 1834 return result; 1835 } 1836 1837 // Expansion didn't work, we'll try to do a Full GC. 1838 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1839 false, /* clear_all_soft_refs */ 1840 word_size); 1841 if (!gc_succeeded) { 1842 *succeeded = false; 1843 return NULL; 1844 } 1845 1846 // Retry the allocation 1847 result = attempt_allocation_at_safepoint(word_size, 1848 context, 1849 true /* expect_null_mutator_alloc_region */); 1850 if (result != NULL) { 1851 assert(*succeeded, "sanity"); 1852 return result; 1853 } 1854 1855 // Then, try a Full GC that will collect all soft references. 1856 gc_succeeded = do_collection(false, /* explicit_gc */ 1857 true, /* clear_all_soft_refs */ 1858 word_size); 1859 if (!gc_succeeded) { 1860 *succeeded = false; 1861 return NULL; 1862 } 1863 1864 // Retry the allocation once more 1865 result = attempt_allocation_at_safepoint(word_size, 1866 context, 1867 true /* expect_null_mutator_alloc_region */); 1868 if (result != NULL) { 1869 assert(*succeeded, "sanity"); 1870 return result; 1871 } 1872 1873 assert(!collector_policy()->should_clear_all_soft_refs(), 1874 "Flag should have been handled and cleared prior to this point"); 1875 1876 // What else? We might try synchronous finalization later. If the total 1877 // space available is large enough for the allocation, then a more 1878 // complete compaction phase than we've tried so far might be 1879 // appropriate. 1880 assert(*succeeded, "sanity"); 1881 return NULL; 1882 } 1883 1884 // Attempting to expand the heap sufficiently 1885 // to support an allocation of the given "word_size". If 1886 // successful, perform the allocation and return the address of the 1887 // allocated block, or else "NULL". 1888 1889 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { 1890 assert_at_safepoint(true /* should_be_vm_thread */); 1891 1892 verify_region_sets_optional(); 1893 1894 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1895 ergo_verbose1(ErgoHeapSizing, 1896 "attempt heap expansion", 1897 ergo_format_reason("allocation request failed") 1898 ergo_format_byte("allocation request"), 1899 word_size * HeapWordSize); 1900 if (expand(expand_bytes)) { 1901 _hrm.verify_optional(); 1902 verify_region_sets_optional(); 1903 return attempt_allocation_at_safepoint(word_size, 1904 context, 1905 false /* expect_null_mutator_alloc_region */); 1906 } 1907 return NULL; 1908 } 1909 1910 bool G1CollectedHeap::expand(size_t expand_bytes) { 1911 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1912 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1913 HeapRegion::GrainBytes); 1914 ergo_verbose2(ErgoHeapSizing, 1915 "expand the heap", 1916 ergo_format_byte("requested expansion amount") 1917 ergo_format_byte("attempted expansion amount"), 1918 expand_bytes, aligned_expand_bytes); 1919 1920 if (is_maximal_no_gc()) { 1921 ergo_verbose0(ErgoHeapSizing, 1922 "did not expand the heap", 1923 ergo_format_reason("heap already fully expanded")); 1924 return false; 1925 } 1926 1927 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1928 assert(regions_to_expand > 0, "Must expand by at least one region"); 1929 1930 uint expanded_by = _hrm.expand_by(regions_to_expand); 1931 1932 if (expanded_by > 0) { 1933 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1934 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1935 g1_policy()->record_new_heap_size(num_regions()); 1936 } else { 1937 ergo_verbose0(ErgoHeapSizing, 1938 "did not expand the heap", 1939 ergo_format_reason("heap expansion operation failed")); 1940 // The expansion of the virtual storage space was unsuccessful. 1941 // Let's see if it was because we ran out of swap. 1942 if (G1ExitOnExpansionFailure && 1943 _hrm.available() >= regions_to_expand) { 1944 // We had head room... 1945 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1946 } 1947 } 1948 return regions_to_expand > 0; 1949 } 1950 1951 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1952 size_t aligned_shrink_bytes = 1953 ReservedSpace::page_align_size_down(shrink_bytes); 1954 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1955 HeapRegion::GrainBytes); 1956 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1957 1958 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1959 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1960 1961 ergo_verbose3(ErgoHeapSizing, 1962 "shrink the heap", 1963 ergo_format_byte("requested shrinking amount") 1964 ergo_format_byte("aligned shrinking amount") 1965 ergo_format_byte("attempted shrinking amount"), 1966 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1967 if (num_regions_removed > 0) { 1968 g1_policy()->record_new_heap_size(num_regions()); 1969 } else { 1970 ergo_verbose0(ErgoHeapSizing, 1971 "did not shrink the heap", 1972 ergo_format_reason("heap shrinking operation failed")); 1973 } 1974 } 1975 1976 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1977 verify_region_sets_optional(); 1978 1979 // We should only reach here at the end of a Full GC which means we 1980 // should not not be holding to any GC alloc regions. The method 1981 // below will make sure of that and do any remaining clean up. 1982 _allocator->abandon_gc_alloc_regions(); 1983 1984 // Instead of tearing down / rebuilding the free lists here, we 1985 // could instead use the remove_all_pending() method on free_list to 1986 // remove only the ones that we need to remove. 1987 tear_down_region_sets(true /* free_list_only */); 1988 shrink_helper(shrink_bytes); 1989 rebuild_region_sets(true /* free_list_only */); 1990 1991 _hrm.verify_optional(); 1992 verify_region_sets_optional(); 1993 } 1994 1995 // Public methods. 1996 1997 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1998 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1999 #endif // _MSC_VER 2000 2001 2002 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 2003 CollectedHeap(), 2004 _g1_policy(policy_), 2005 _dirty_card_queue_set(false), 2006 _into_cset_dirty_card_queue_set(false), 2007 _is_alive_closure_cm(this), 2008 _is_alive_closure_stw(this), 2009 _ref_processor_cm(NULL), 2010 _ref_processor_stw(NULL), 2011 _bot_shared(NULL), 2012 _cg1r(NULL), 2013 _g1mm(NULL), 2014 _refine_cte_cl(NULL), 2015 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 2016 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 2017 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 2018 _humongous_reclaim_candidates(), 2019 _has_humongous_reclaim_candidates(false), 2020 _archive_allocator(NULL), 2021 _free_regions_coming(false), 2022 _young_list(new YoungList(this)), 2023 _gc_time_stamp(0), 2024 _summary_bytes_used(0), 2025 _survivor_plab_stats(YoungPLABSize, PLABWeight), 2026 _old_plab_stats(OldPLABSize, PLABWeight), 2027 _expand_heap_after_alloc_failure(true), 2028 _surviving_young_words(NULL), 2029 _old_marking_cycles_started(0), 2030 _old_marking_cycles_completed(0), 2031 _heap_summary_sent(false), 2032 _in_cset_fast_test(), 2033 _dirty_cards_region_list(NULL), 2034 _worker_cset_start_region(NULL), 2035 _worker_cset_start_region_time_stamp(NULL), 2036 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 2037 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 2038 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 2039 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 2040 2041 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads, 2042 /* are_GC_task_threads */true, 2043 /* are_ConcurrentGC_threads */false); 2044 _workers->initialize_workers(); 2045 2046 _allocator = G1Allocator::create_allocator(this); 2047 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 2048 2049 // Override the default _filler_array_max_size so that no humongous filler 2050 // objects are created. 2051 _filler_array_max_size = _humongous_object_threshold_in_words; 2052 2053 uint n_queues = ParallelGCThreads; 2054 _task_queues = new RefToScanQueueSet(n_queues); 2055 2056 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 2057 assert(n_rem_sets > 0, "Invariant."); 2058 2059 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 2060 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC); 2061 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 2062 2063 for (uint i = 0; i < n_queues; i++) { 2064 RefToScanQueue* q = new RefToScanQueue(); 2065 q->initialize(); 2066 _task_queues->register_queue(i, q); 2067 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 2068 } 2069 clear_cset_start_regions(); 2070 2071 // Initialize the G1EvacuationFailureALot counters and flags. 2072 NOT_PRODUCT(reset_evacuation_should_fail();) 2073 2074 guarantee(_task_queues != NULL, "task_queues allocation failure."); 2075 } 2076 2077 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 2078 size_t size, 2079 size_t translation_factor) { 2080 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 2081 // Allocate a new reserved space, preferring to use large pages. 2082 ReservedSpace rs(size, preferred_page_size); 2083 G1RegionToSpaceMapper* result = 2084 G1RegionToSpaceMapper::create_mapper(rs, 2085 size, 2086 rs.alignment(), 2087 HeapRegion::GrainBytes, 2088 translation_factor, 2089 mtGC); 2090 if (TracePageSizes) { 2091 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT, 2092 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size); 2093 } 2094 return result; 2095 } 2096 2097 jint G1CollectedHeap::initialize() { 2098 CollectedHeap::pre_initialize(); 2099 os::enable_vtime(); 2100 2101 G1Log::init(); 2102 2103 // Necessary to satisfy locking discipline assertions. 2104 2105 MutexLocker x(Heap_lock); 2106 2107 // We have to initialize the printer before committing the heap, as 2108 // it will be used then. 2109 _hr_printer.set_active(G1PrintHeapRegions); 2110 2111 // While there are no constraints in the GC code that HeapWordSize 2112 // be any particular value, there are multiple other areas in the 2113 // system which believe this to be true (e.g. oop->object_size in some 2114 // cases incorrectly returns the size in wordSize units rather than 2115 // HeapWordSize). 2116 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 2117 2118 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 2119 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 2120 size_t heap_alignment = collector_policy()->heap_alignment(); 2121 2122 // Ensure that the sizes are properly aligned. 2123 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2124 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2125 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 2126 2127 _refine_cte_cl = new RefineCardTableEntryClosure(); 2128 2129 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl); 2130 2131 // Reserve the maximum. 2132 2133 // When compressed oops are enabled, the preferred heap base 2134 // is calculated by subtracting the requested size from the 2135 // 32Gb boundary and using the result as the base address for 2136 // heap reservation. If the requested size is not aligned to 2137 // HeapRegion::GrainBytes (i.e. the alignment that is passed 2138 // into the ReservedHeapSpace constructor) then the actual 2139 // base of the reserved heap may end up differing from the 2140 // address that was requested (i.e. the preferred heap base). 2141 // If this happens then we could end up using a non-optimal 2142 // compressed oops mode. 2143 2144 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 2145 heap_alignment); 2146 2147 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 2148 2149 // Create the barrier set for the entire reserved region. 2150 G1SATBCardTableLoggingModRefBS* bs 2151 = new G1SATBCardTableLoggingModRefBS(reserved_region()); 2152 bs->initialize(); 2153 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); 2154 set_barrier_set(bs); 2155 2156 // Also create a G1 rem set. 2157 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 2158 2159 // Carve out the G1 part of the heap. 2160 2161 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 2162 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 2163 G1RegionToSpaceMapper* heap_storage = 2164 G1RegionToSpaceMapper::create_mapper(g1_rs, 2165 g1_rs.size(), 2166 page_size, 2167 HeapRegion::GrainBytes, 2168 1, 2169 mtJavaHeap); 2170 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(), 2171 max_byte_size, page_size, 2172 heap_rs.base(), 2173 heap_rs.size()); 2174 heap_storage->set_mapping_changed_listener(&_listener); 2175 2176 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 2177 G1RegionToSpaceMapper* bot_storage = 2178 create_aux_memory_mapper("Block offset table", 2179 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize), 2180 G1BlockOffsetSharedArray::heap_map_factor()); 2181 2182 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); 2183 G1RegionToSpaceMapper* cardtable_storage = 2184 create_aux_memory_mapper("Card table", 2185 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize), 2186 G1SATBCardTableLoggingModRefBS::heap_map_factor()); 2187 2188 G1RegionToSpaceMapper* card_counts_storage = 2189 create_aux_memory_mapper("Card counts table", 2190 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 2191 G1CardCounts::heap_map_factor()); 2192 2193 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); 2194 G1RegionToSpaceMapper* prev_bitmap_storage = 2195 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor()); 2196 G1RegionToSpaceMapper* next_bitmap_storage = 2197 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor()); 2198 2199 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 2200 g1_barrier_set()->initialize(cardtable_storage); 2201 // Do later initialization work for concurrent refinement. 2202 _cg1r->init(card_counts_storage); 2203 2204 // 6843694 - ensure that the maximum region index can fit 2205 // in the remembered set structures. 2206 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2207 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2208 2209 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2210 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2211 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2212 "too many cards per region"); 2213 2214 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 2215 2216 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage); 2217 2218 { 2219 HeapWord* start = _hrm.reserved().start(); 2220 HeapWord* end = _hrm.reserved().end(); 2221 size_t granularity = HeapRegion::GrainBytes; 2222 2223 _in_cset_fast_test.initialize(start, end, granularity); 2224 _humongous_reclaim_candidates.initialize(start, end, granularity); 2225 } 2226 2227 // Create the ConcurrentMark data structure and thread. 2228 // (Must do this late, so that "max_regions" is defined.) 2229 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 2230 if (_cm == NULL || !_cm->completed_initialization()) { 2231 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 2232 return JNI_ENOMEM; 2233 } 2234 _cmThread = _cm->cmThread(); 2235 2236 // Initialize the from_card cache structure of HeapRegionRemSet. 2237 HeapRegionRemSet::init_heap(max_regions()); 2238 2239 // Now expand into the initial heap size. 2240 if (!expand(init_byte_size)) { 2241 vm_shutdown_during_initialization("Failed to allocate initial heap."); 2242 return JNI_ENOMEM; 2243 } 2244 2245 // Perform any initialization actions delegated to the policy. 2246 g1_policy()->init(); 2247 2248 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2249 SATB_Q_FL_lock, 2250 G1SATBProcessCompletedThreshold, 2251 Shared_SATB_Q_lock); 2252 2253 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 2254 DirtyCardQ_CBL_mon, 2255 DirtyCardQ_FL_lock, 2256 concurrent_g1_refine()->yellow_zone(), 2257 concurrent_g1_refine()->red_zone(), 2258 Shared_DirtyCardQ_lock); 2259 2260 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 2261 DirtyCardQ_CBL_mon, 2262 DirtyCardQ_FL_lock, 2263 -1, // never trigger processing 2264 -1, // no limit on length 2265 Shared_DirtyCardQ_lock, 2266 &JavaThread::dirty_card_queue_set()); 2267 2268 // Initialize the card queue set used to hold cards containing 2269 // references into the collection set. 2270 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 2271 DirtyCardQ_CBL_mon, 2272 DirtyCardQ_FL_lock, 2273 -1, // never trigger processing 2274 -1, // no limit on length 2275 Shared_DirtyCardQ_lock, 2276 &JavaThread::dirty_card_queue_set()); 2277 2278 // Here we allocate the dummy HeapRegion that is required by the 2279 // G1AllocRegion class. 2280 HeapRegion* dummy_region = _hrm.get_dummy_region(); 2281 2282 // We'll re-use the same region whether the alloc region will 2283 // require BOT updates or not and, if it doesn't, then a non-young 2284 // region will complain that it cannot support allocations without 2285 // BOT updates. So we'll tag the dummy region as eden to avoid that. 2286 dummy_region->set_eden(); 2287 // Make sure it's full. 2288 dummy_region->set_top(dummy_region->end()); 2289 G1AllocRegion::setup(this, dummy_region); 2290 2291 _allocator->init_mutator_alloc_region(); 2292 2293 // Do create of the monitoring and management support so that 2294 // values in the heap have been properly initialized. 2295 _g1mm = new G1MonitoringSupport(this); 2296 2297 G1StringDedup::initialize(); 2298 2299 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC); 2300 for (uint i = 0; i < ParallelGCThreads; i++) { 2301 new (&_preserved_objs[i]) OopAndMarkOopStack(); 2302 } 2303 2304 return JNI_OK; 2305 } 2306 2307 void G1CollectedHeap::stop() { 2308 // Stop all concurrent threads. We do this to make sure these threads 2309 // do not continue to execute and access resources (e.g. gclog_or_tty) 2310 // that are destroyed during shutdown. 2311 _cg1r->stop(); 2312 _cmThread->stop(); 2313 if (G1StringDedup::is_enabled()) { 2314 G1StringDedup::stop(); 2315 } 2316 } 2317 2318 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2319 return HeapRegion::max_region_size(); 2320 } 2321 2322 void G1CollectedHeap::post_initialize() { 2323 CollectedHeap::post_initialize(); 2324 ref_processing_init(); 2325 } 2326 2327 void G1CollectedHeap::ref_processing_init() { 2328 // Reference processing in G1 currently works as follows: 2329 // 2330 // * There are two reference processor instances. One is 2331 // used to record and process discovered references 2332 // during concurrent marking; the other is used to 2333 // record and process references during STW pauses 2334 // (both full and incremental). 2335 // * Both ref processors need to 'span' the entire heap as 2336 // the regions in the collection set may be dotted around. 2337 // 2338 // * For the concurrent marking ref processor: 2339 // * Reference discovery is enabled at initial marking. 2340 // * Reference discovery is disabled and the discovered 2341 // references processed etc during remarking. 2342 // * Reference discovery is MT (see below). 2343 // * Reference discovery requires a barrier (see below). 2344 // * Reference processing may or may not be MT 2345 // (depending on the value of ParallelRefProcEnabled 2346 // and ParallelGCThreads). 2347 // * A full GC disables reference discovery by the CM 2348 // ref processor and abandons any entries on it's 2349 // discovered lists. 2350 // 2351 // * For the STW processor: 2352 // * Non MT discovery is enabled at the start of a full GC. 2353 // * Processing and enqueueing during a full GC is non-MT. 2354 // * During a full GC, references are processed after marking. 2355 // 2356 // * Discovery (may or may not be MT) is enabled at the start 2357 // of an incremental evacuation pause. 2358 // * References are processed near the end of a STW evacuation pause. 2359 // * For both types of GC: 2360 // * Discovery is atomic - i.e. not concurrent. 2361 // * Reference discovery will not need a barrier. 2362 2363 MemRegion mr = reserved_region(); 2364 2365 // Concurrent Mark ref processor 2366 _ref_processor_cm = 2367 new ReferenceProcessor(mr, // span 2368 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2369 // mt processing 2370 ParallelGCThreads, 2371 // degree of mt processing 2372 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2373 // mt discovery 2374 MAX2(ParallelGCThreads, ConcGCThreads), 2375 // degree of mt discovery 2376 false, 2377 // Reference discovery is not atomic 2378 &_is_alive_closure_cm); 2379 // is alive closure 2380 // (for efficiency/performance) 2381 2382 // STW ref processor 2383 _ref_processor_stw = 2384 new ReferenceProcessor(mr, // span 2385 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2386 // mt processing 2387 ParallelGCThreads, 2388 // degree of mt processing 2389 (ParallelGCThreads > 1), 2390 // mt discovery 2391 ParallelGCThreads, 2392 // degree of mt discovery 2393 true, 2394 // Reference discovery is atomic 2395 &_is_alive_closure_stw); 2396 // is alive closure 2397 // (for efficiency/performance) 2398 } 2399 2400 size_t G1CollectedHeap::capacity() const { 2401 return _hrm.length() * HeapRegion::GrainBytes; 2402 } 2403 2404 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2405 assert(!hr->is_continues_humongous(), "pre-condition"); 2406 hr->reset_gc_time_stamp(); 2407 if (hr->is_starts_humongous()) { 2408 uint first_index = hr->hrm_index() + 1; 2409 uint last_index = hr->last_hc_index(); 2410 for (uint i = first_index; i < last_index; i += 1) { 2411 HeapRegion* chr = region_at(i); 2412 assert(chr->is_continues_humongous(), "sanity"); 2413 chr->reset_gc_time_stamp(); 2414 } 2415 } 2416 } 2417 2418 #ifndef PRODUCT 2419 2420 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2421 private: 2422 unsigned _gc_time_stamp; 2423 bool _failures; 2424 2425 public: 2426 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2427 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2428 2429 virtual bool doHeapRegion(HeapRegion* hr) { 2430 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2431 if (_gc_time_stamp != region_gc_time_stamp) { 2432 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, " 2433 "expected %d", HR_FORMAT_PARAMS(hr), 2434 region_gc_time_stamp, _gc_time_stamp); 2435 _failures = true; 2436 } 2437 return false; 2438 } 2439 2440 bool failures() { return _failures; } 2441 }; 2442 2443 void G1CollectedHeap::check_gc_time_stamps() { 2444 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2445 heap_region_iterate(&cl); 2446 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2447 } 2448 #endif // PRODUCT 2449 2450 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2451 DirtyCardQueue* into_cset_dcq, 2452 bool concurrent, 2453 uint worker_i) { 2454 // Clean cards in the hot card cache 2455 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2456 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2457 2458 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2459 size_t n_completed_buffers = 0; 2460 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2461 n_completed_buffers++; 2462 } 2463 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); 2464 dcqs.clear_n_completed_buffers(); 2465 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2466 } 2467 2468 // Computes the sum of the storage used by the various regions. 2469 size_t G1CollectedHeap::used() const { 2470 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 2471 if (_archive_allocator != NULL) { 2472 result += _archive_allocator->used(); 2473 } 2474 return result; 2475 } 2476 2477 size_t G1CollectedHeap::used_unlocked() const { 2478 return _summary_bytes_used; 2479 } 2480 2481 class SumUsedClosure: public HeapRegionClosure { 2482 size_t _used; 2483 public: 2484 SumUsedClosure() : _used(0) {} 2485 bool doHeapRegion(HeapRegion* r) { 2486 if (!r->is_continues_humongous()) { 2487 _used += r->used(); 2488 } 2489 return false; 2490 } 2491 size_t result() { return _used; } 2492 }; 2493 2494 size_t G1CollectedHeap::recalculate_used() const { 2495 double recalculate_used_start = os::elapsedTime(); 2496 2497 SumUsedClosure blk; 2498 heap_region_iterate(&blk); 2499 2500 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2501 return blk.result(); 2502 } 2503 2504 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2505 switch (cause) { 2506 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2507 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2508 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 2509 case GCCause::_g1_humongous_allocation: return true; 2510 case GCCause::_update_allocation_context_stats_inc: return true; 2511 case GCCause::_wb_conc_mark: return true; 2512 default: return false; 2513 } 2514 } 2515 2516 #ifndef PRODUCT 2517 void G1CollectedHeap::allocate_dummy_regions() { 2518 // Let's fill up most of the region 2519 size_t word_size = HeapRegion::GrainWords - 1024; 2520 // And as a result the region we'll allocate will be humongous. 2521 guarantee(is_humongous(word_size), "sanity"); 2522 2523 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2524 // Let's use the existing mechanism for the allocation 2525 HeapWord* dummy_obj = humongous_obj_allocate(word_size, 2526 AllocationContext::system()); 2527 if (dummy_obj != NULL) { 2528 MemRegion mr(dummy_obj, word_size); 2529 CollectedHeap::fill_with_object(mr); 2530 } else { 2531 // If we can't allocate once, we probably cannot allocate 2532 // again. Let's get out of the loop. 2533 break; 2534 } 2535 } 2536 } 2537 #endif // !PRODUCT 2538 2539 void G1CollectedHeap::increment_old_marking_cycles_started() { 2540 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2541 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2542 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2543 _old_marking_cycles_started, _old_marking_cycles_completed)); 2544 2545 _old_marking_cycles_started++; 2546 } 2547 2548 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2549 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2550 2551 // We assume that if concurrent == true, then the caller is a 2552 // concurrent thread that was joined the Suspendible Thread 2553 // Set. If there's ever a cheap way to check this, we should add an 2554 // assert here. 2555 2556 // Given that this method is called at the end of a Full GC or of a 2557 // concurrent cycle, and those can be nested (i.e., a Full GC can 2558 // interrupt a concurrent cycle), the number of full collections 2559 // completed should be either one (in the case where there was no 2560 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2561 // behind the number of full collections started. 2562 2563 // This is the case for the inner caller, i.e. a Full GC. 2564 assert(concurrent || 2565 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2566 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2567 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2568 "is inconsistent with _old_marking_cycles_completed = %u", 2569 _old_marking_cycles_started, _old_marking_cycles_completed)); 2570 2571 // This is the case for the outer caller, i.e. the concurrent cycle. 2572 assert(!concurrent || 2573 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2574 err_msg("for outer caller (concurrent cycle): " 2575 "_old_marking_cycles_started = %u " 2576 "is inconsistent with _old_marking_cycles_completed = %u", 2577 _old_marking_cycles_started, _old_marking_cycles_completed)); 2578 2579 _old_marking_cycles_completed += 1; 2580 2581 // We need to clear the "in_progress" flag in the CM thread before 2582 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2583 // is set) so that if a waiter requests another System.gc() it doesn't 2584 // incorrectly see that a marking cycle is still in progress. 2585 if (concurrent) { 2586 _cmThread->set_idle(); 2587 } 2588 2589 // This notify_all() will ensure that a thread that called 2590 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2591 // and it's waiting for a full GC to finish will be woken up. It is 2592 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2593 FullGCCount_lock->notify_all(); 2594 } 2595 2596 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2597 collector_state()->set_concurrent_cycle_started(true); 2598 _gc_timer_cm->register_gc_start(start_time); 2599 2600 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2601 trace_heap_before_gc(_gc_tracer_cm); 2602 } 2603 2604 void G1CollectedHeap::register_concurrent_cycle_end() { 2605 if (collector_state()->concurrent_cycle_started()) { 2606 if (_cm->has_aborted()) { 2607 _gc_tracer_cm->report_concurrent_mode_failure(); 2608 } 2609 2610 _gc_timer_cm->register_gc_end(); 2611 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2612 2613 // Clear state variables to prepare for the next concurrent cycle. 2614 collector_state()->set_concurrent_cycle_started(false); 2615 _heap_summary_sent = false; 2616 } 2617 } 2618 2619 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2620 if (collector_state()->concurrent_cycle_started()) { 2621 // This function can be called when: 2622 // the cleanup pause is run 2623 // the concurrent cycle is aborted before the cleanup pause. 2624 // the concurrent cycle is aborted after the cleanup pause, 2625 // but before the concurrent cycle end has been registered. 2626 // Make sure that we only send the heap information once. 2627 if (!_heap_summary_sent) { 2628 trace_heap_after_gc(_gc_tracer_cm); 2629 _heap_summary_sent = true; 2630 } 2631 } 2632 } 2633 2634 void G1CollectedHeap::collect(GCCause::Cause cause) { 2635 assert_heap_not_locked(); 2636 2637 uint gc_count_before; 2638 uint old_marking_count_before; 2639 uint full_gc_count_before; 2640 bool retry_gc; 2641 2642 do { 2643 retry_gc = false; 2644 2645 { 2646 MutexLocker ml(Heap_lock); 2647 2648 // Read the GC count while holding the Heap_lock 2649 gc_count_before = total_collections(); 2650 full_gc_count_before = total_full_collections(); 2651 old_marking_count_before = _old_marking_cycles_started; 2652 } 2653 2654 if (should_do_concurrent_full_gc(cause)) { 2655 // Schedule an initial-mark evacuation pause that will start a 2656 // concurrent cycle. We're setting word_size to 0 which means that 2657 // we are not requesting a post-GC allocation. 2658 VM_G1IncCollectionPause op(gc_count_before, 2659 0, /* word_size */ 2660 true, /* should_initiate_conc_mark */ 2661 g1_policy()->max_pause_time_ms(), 2662 cause); 2663 op.set_allocation_context(AllocationContext::current()); 2664 2665 VMThread::execute(&op); 2666 if (!op.pause_succeeded()) { 2667 if (old_marking_count_before == _old_marking_cycles_started) { 2668 retry_gc = op.should_retry_gc(); 2669 } else { 2670 // A Full GC happened while we were trying to schedule the 2671 // initial-mark GC. No point in starting a new cycle given 2672 // that the whole heap was collected anyway. 2673 } 2674 2675 if (retry_gc) { 2676 if (GC_locker::is_active_and_needs_gc()) { 2677 GC_locker::stall_until_clear(); 2678 } 2679 } 2680 } 2681 } else { 2682 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2683 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2684 2685 // Schedule a standard evacuation pause. We're setting word_size 2686 // to 0 which means that we are not requesting a post-GC allocation. 2687 VM_G1IncCollectionPause op(gc_count_before, 2688 0, /* word_size */ 2689 false, /* should_initiate_conc_mark */ 2690 g1_policy()->max_pause_time_ms(), 2691 cause); 2692 VMThread::execute(&op); 2693 } else { 2694 // Schedule a Full GC. 2695 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2696 VMThread::execute(&op); 2697 } 2698 } 2699 } while (retry_gc); 2700 } 2701 2702 bool G1CollectedHeap::is_in(const void* p) const { 2703 if (_hrm.reserved().contains(p)) { 2704 // Given that we know that p is in the reserved space, 2705 // heap_region_containing_raw() should successfully 2706 // return the containing region. 2707 HeapRegion* hr = heap_region_containing_raw(p); 2708 return hr->is_in(p); 2709 } else { 2710 return false; 2711 } 2712 } 2713 2714 #ifdef ASSERT 2715 bool G1CollectedHeap::is_in_exact(const void* p) const { 2716 bool contains = reserved_region().contains(p); 2717 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2718 if (contains && available) { 2719 return true; 2720 } else { 2721 return false; 2722 } 2723 } 2724 #endif 2725 2726 bool G1CollectedHeap::obj_in_cs(oop obj) { 2727 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj); 2728 return r != NULL && r->in_collection_set(); 2729 } 2730 2731 // Iteration functions. 2732 2733 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. 2734 2735 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2736 ExtendedOopClosure* _cl; 2737 public: 2738 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} 2739 bool doHeapRegion(HeapRegion* r) { 2740 if (!r->is_continues_humongous()) { 2741 r->oop_iterate(_cl); 2742 } 2743 return false; 2744 } 2745 }; 2746 2747 // Iterates an ObjectClosure over all objects within a HeapRegion. 2748 2749 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2750 ObjectClosure* _cl; 2751 public: 2752 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2753 bool doHeapRegion(HeapRegion* r) { 2754 if (!r->is_continues_humongous()) { 2755 r->object_iterate(_cl); 2756 } 2757 return false; 2758 } 2759 }; 2760 2761 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2762 IterateObjectClosureRegionClosure blk(cl); 2763 heap_region_iterate(&blk); 2764 } 2765 2766 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2767 _hrm.iterate(cl); 2768 } 2769 2770 void 2771 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, 2772 uint worker_id, 2773 HeapRegionClaimer *hrclaimer, 2774 bool concurrent) const { 2775 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); 2776 } 2777 2778 // Clear the cached CSet starting regions and (more importantly) 2779 // the time stamps. Called when we reset the GC time stamp. 2780 void G1CollectedHeap::clear_cset_start_regions() { 2781 assert(_worker_cset_start_region != NULL, "sanity"); 2782 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2783 2784 for (uint i = 0; i < ParallelGCThreads; i++) { 2785 _worker_cset_start_region[i] = NULL; 2786 _worker_cset_start_region_time_stamp[i] = 0; 2787 } 2788 } 2789 2790 // Given the id of a worker, obtain or calculate a suitable 2791 // starting region for iterating over the current collection set. 2792 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2793 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2794 2795 HeapRegion* result = NULL; 2796 unsigned gc_time_stamp = get_gc_time_stamp(); 2797 2798 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2799 // Cached starting region for current worker was set 2800 // during the current pause - so it's valid. 2801 // Note: the cached starting heap region may be NULL 2802 // (when the collection set is empty). 2803 result = _worker_cset_start_region[worker_i]; 2804 assert(result == NULL || result->in_collection_set(), "sanity"); 2805 return result; 2806 } 2807 2808 // The cached entry was not valid so let's calculate 2809 // a suitable starting heap region for this worker. 2810 2811 // We want the parallel threads to start their collection 2812 // set iteration at different collection set regions to 2813 // avoid contention. 2814 // If we have: 2815 // n collection set regions 2816 // p threads 2817 // Then thread t will start at region floor ((t * n) / p) 2818 2819 result = g1_policy()->collection_set(); 2820 uint cs_size = g1_policy()->cset_region_length(); 2821 uint active_workers = workers()->active_workers(); 2822 2823 uint end_ind = (cs_size * worker_i) / active_workers; 2824 uint start_ind = 0; 2825 2826 if (worker_i > 0 && 2827 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2828 // Previous workers starting region is valid 2829 // so let's iterate from there 2830 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2831 result = _worker_cset_start_region[worker_i - 1]; 2832 } 2833 2834 for (uint i = start_ind; i < end_ind; i++) { 2835 result = result->next_in_collection_set(); 2836 } 2837 2838 // Note: the calculated starting heap region may be NULL 2839 // (when the collection set is empty). 2840 assert(result == NULL || result->in_collection_set(), "sanity"); 2841 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2842 "should be updated only once per pause"); 2843 _worker_cset_start_region[worker_i] = result; 2844 OrderAccess::storestore(); 2845 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2846 return result; 2847 } 2848 2849 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2850 HeapRegion* r = g1_policy()->collection_set(); 2851 while (r != NULL) { 2852 HeapRegion* next = r->next_in_collection_set(); 2853 if (cl->doHeapRegion(r)) { 2854 cl->incomplete(); 2855 return; 2856 } 2857 r = next; 2858 } 2859 } 2860 2861 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2862 HeapRegionClosure *cl) { 2863 if (r == NULL) { 2864 // The CSet is empty so there's nothing to do. 2865 return; 2866 } 2867 2868 assert(r->in_collection_set(), 2869 "Start region must be a member of the collection set."); 2870 HeapRegion* cur = r; 2871 while (cur != NULL) { 2872 HeapRegion* next = cur->next_in_collection_set(); 2873 if (cl->doHeapRegion(cur) && false) { 2874 cl->incomplete(); 2875 return; 2876 } 2877 cur = next; 2878 } 2879 cur = g1_policy()->collection_set(); 2880 while (cur != r) { 2881 HeapRegion* next = cur->next_in_collection_set(); 2882 if (cl->doHeapRegion(cur) && false) { 2883 cl->incomplete(); 2884 return; 2885 } 2886 cur = next; 2887 } 2888 } 2889 2890 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { 2891 HeapRegion* result = _hrm.next_region_in_heap(from); 2892 while (result != NULL && result->is_pinned()) { 2893 result = _hrm.next_region_in_heap(result); 2894 } 2895 return result; 2896 } 2897 2898 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2899 HeapRegion* hr = heap_region_containing(addr); 2900 return hr->block_start(addr); 2901 } 2902 2903 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2904 HeapRegion* hr = heap_region_containing(addr); 2905 return hr->block_size(addr); 2906 } 2907 2908 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2909 HeapRegion* hr = heap_region_containing(addr); 2910 return hr->block_is_obj(addr); 2911 } 2912 2913 bool G1CollectedHeap::supports_tlab_allocation() const { 2914 return true; 2915 } 2916 2917 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2918 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2919 } 2920 2921 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2922 return young_list()->eden_used_bytes(); 2923 } 2924 2925 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2926 // must be smaller than the humongous object limit. 2927 size_t G1CollectedHeap::max_tlab_size() const { 2928 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 2929 } 2930 2931 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2932 AllocationContext_t context = AllocationContext::current(); 2933 return _allocator->unsafe_max_tlab_alloc(context); 2934 } 2935 2936 size_t G1CollectedHeap::max_capacity() const { 2937 return _hrm.reserved().byte_size(); 2938 } 2939 2940 jlong G1CollectedHeap::millis_since_last_gc() { 2941 // assert(false, "NYI"); 2942 return 0; 2943 } 2944 2945 void G1CollectedHeap::prepare_for_verify() { 2946 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2947 ensure_parsability(false); 2948 } 2949 g1_rem_set()->prepare_for_verify(); 2950 } 2951 2952 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 2953 VerifyOption vo) { 2954 switch (vo) { 2955 case VerifyOption_G1UsePrevMarking: 2956 return hr->obj_allocated_since_prev_marking(obj); 2957 case VerifyOption_G1UseNextMarking: 2958 return hr->obj_allocated_since_next_marking(obj); 2959 case VerifyOption_G1UseMarkWord: 2960 return false; 2961 default: 2962 ShouldNotReachHere(); 2963 } 2964 return false; // keep some compilers happy 2965 } 2966 2967 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 2968 switch (vo) { 2969 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 2970 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 2971 case VerifyOption_G1UseMarkWord: return NULL; 2972 default: ShouldNotReachHere(); 2973 } 2974 return NULL; // keep some compilers happy 2975 } 2976 2977 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 2978 switch (vo) { 2979 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 2980 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 2981 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 2982 default: ShouldNotReachHere(); 2983 } 2984 return false; // keep some compilers happy 2985 } 2986 2987 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 2988 switch (vo) { 2989 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 2990 case VerifyOption_G1UseNextMarking: return "NTAMS"; 2991 case VerifyOption_G1UseMarkWord: return "NONE"; 2992 default: ShouldNotReachHere(); 2993 } 2994 return NULL; // keep some compilers happy 2995 } 2996 2997 class VerifyRootsClosure: public OopClosure { 2998 private: 2999 G1CollectedHeap* _g1h; 3000 VerifyOption _vo; 3001 bool _failures; 3002 public: 3003 // _vo == UsePrevMarking -> use "prev" marking information, 3004 // _vo == UseNextMarking -> use "next" marking information, 3005 // _vo == UseMarkWord -> use mark word from object header. 3006 VerifyRootsClosure(VerifyOption vo) : 3007 _g1h(G1CollectedHeap::heap()), 3008 _vo(vo), 3009 _failures(false) { } 3010 3011 bool failures() { return _failures; } 3012 3013 template <class T> void do_oop_nv(T* p) { 3014 T heap_oop = oopDesc::load_heap_oop(p); 3015 if (!oopDesc::is_null(heap_oop)) { 3016 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3017 if (_g1h->is_obj_dead_cond(obj, _vo)) { 3018 gclog_or_tty->print_cr("Root location " PTR_FORMAT " " 3019 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj)); 3020 if (_vo == VerifyOption_G1UseMarkWord) { 3021 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark()); 3022 } 3023 obj->print_on(gclog_or_tty); 3024 _failures = true; 3025 } 3026 } 3027 } 3028 3029 void do_oop(oop* p) { do_oop_nv(p); } 3030 void do_oop(narrowOop* p) { do_oop_nv(p); } 3031 }; 3032 3033 class G1VerifyCodeRootOopClosure: public OopClosure { 3034 G1CollectedHeap* _g1h; 3035 OopClosure* _root_cl; 3036 nmethod* _nm; 3037 VerifyOption _vo; 3038 bool _failures; 3039 3040 template <class T> void do_oop_work(T* p) { 3041 // First verify that this root is live 3042 _root_cl->do_oop(p); 3043 3044 if (!G1VerifyHeapRegionCodeRoots) { 3045 // We're not verifying the code roots attached to heap region. 3046 return; 3047 } 3048 3049 // Don't check the code roots during marking verification in a full GC 3050 if (_vo == VerifyOption_G1UseMarkWord) { 3051 return; 3052 } 3053 3054 // Now verify that the current nmethod (which contains p) is 3055 // in the code root list of the heap region containing the 3056 // object referenced by p. 3057 3058 T heap_oop = oopDesc::load_heap_oop(p); 3059 if (!oopDesc::is_null(heap_oop)) { 3060 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3061 3062 // Now fetch the region containing the object 3063 HeapRegion* hr = _g1h->heap_region_containing(obj); 3064 HeapRegionRemSet* hrrs = hr->rem_set(); 3065 // Verify that the strong code root list for this region 3066 // contains the nmethod 3067 if (!hrrs->strong_code_roots_list_contains(_nm)) { 3068 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " " 3069 "from nmethod " PTR_FORMAT " not in strong " 3070 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")", 3071 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end())); 3072 _failures = true; 3073 } 3074 } 3075 } 3076 3077 public: 3078 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 3079 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 3080 3081 void do_oop(oop* p) { do_oop_work(p); } 3082 void do_oop(narrowOop* p) { do_oop_work(p); } 3083 3084 void set_nmethod(nmethod* nm) { _nm = nm; } 3085 bool failures() { return _failures; } 3086 }; 3087 3088 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 3089 G1VerifyCodeRootOopClosure* _oop_cl; 3090 3091 public: 3092 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 3093 _oop_cl(oop_cl) {} 3094 3095 void do_code_blob(CodeBlob* cb) { 3096 nmethod* nm = cb->as_nmethod_or_null(); 3097 if (nm != NULL) { 3098 _oop_cl->set_nmethod(nm); 3099 nm->oops_do(_oop_cl); 3100 } 3101 } 3102 }; 3103 3104 class YoungRefCounterClosure : public OopClosure { 3105 G1CollectedHeap* _g1h; 3106 int _count; 3107 public: 3108 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 3109 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 3110 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 3111 3112 int count() { return _count; } 3113 void reset_count() { _count = 0; }; 3114 }; 3115 3116 class VerifyKlassClosure: public KlassClosure { 3117 YoungRefCounterClosure _young_ref_counter_closure; 3118 OopClosure *_oop_closure; 3119 public: 3120 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 3121 void do_klass(Klass* k) { 3122 k->oops_do(_oop_closure); 3123 3124 _young_ref_counter_closure.reset_count(); 3125 k->oops_do(&_young_ref_counter_closure); 3126 if (_young_ref_counter_closure.count() > 0) { 3127 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k))); 3128 } 3129 } 3130 }; 3131 3132 class VerifyLivenessOopClosure: public OopClosure { 3133 G1CollectedHeap* _g1h; 3134 VerifyOption _vo; 3135 public: 3136 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 3137 _g1h(g1h), _vo(vo) 3138 { } 3139 void do_oop(narrowOop *p) { do_oop_work(p); } 3140 void do_oop( oop *p) { do_oop_work(p); } 3141 3142 template <class T> void do_oop_work(T *p) { 3143 oop obj = oopDesc::load_decode_heap_oop(p); 3144 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 3145 "Dead object referenced by a not dead object"); 3146 } 3147 }; 3148 3149 class VerifyObjsInRegionClosure: public ObjectClosure { 3150 private: 3151 G1CollectedHeap* _g1h; 3152 size_t _live_bytes; 3153 HeapRegion *_hr; 3154 VerifyOption _vo; 3155 public: 3156 // _vo == UsePrevMarking -> use "prev" marking information, 3157 // _vo == UseNextMarking -> use "next" marking information, 3158 // _vo == UseMarkWord -> use mark word from object header. 3159 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 3160 : _live_bytes(0), _hr(hr), _vo(vo) { 3161 _g1h = G1CollectedHeap::heap(); 3162 } 3163 void do_object(oop o) { 3164 VerifyLivenessOopClosure isLive(_g1h, _vo); 3165 assert(o != NULL, "Huh?"); 3166 if (!_g1h->is_obj_dead_cond(o, _vo)) { 3167 // If the object is alive according to the mark word, 3168 // then verify that the marking information agrees. 3169 // Note we can't verify the contra-positive of the 3170 // above: if the object is dead (according to the mark 3171 // word), it may not be marked, or may have been marked 3172 // but has since became dead, or may have been allocated 3173 // since the last marking. 3174 if (_vo == VerifyOption_G1UseMarkWord) { 3175 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 3176 } 3177 3178 o->oop_iterate_no_header(&isLive); 3179 if (!_hr->obj_allocated_since_prev_marking(o)) { 3180 size_t obj_size = o->size(); // Make sure we don't overflow 3181 _live_bytes += (obj_size * HeapWordSize); 3182 } 3183 } 3184 } 3185 size_t live_bytes() { return _live_bytes; } 3186 }; 3187 3188 class VerifyArchiveOopClosure: public OopClosure { 3189 public: 3190 VerifyArchiveOopClosure(HeapRegion *hr) { } 3191 void do_oop(narrowOop *p) { do_oop_work(p); } 3192 void do_oop( oop *p) { do_oop_work(p); } 3193 3194 template <class T> void do_oop_work(T *p) { 3195 oop obj = oopDesc::load_decode_heap_oop(p); 3196 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj), 3197 err_msg("Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT, 3198 p2i(p), p2i(obj))); 3199 } 3200 }; 3201 3202 class VerifyArchiveRegionClosure: public ObjectClosure { 3203 public: 3204 VerifyArchiveRegionClosure(HeapRegion *hr) { } 3205 // Verify that all object pointers are to archive regions. 3206 void do_object(oop o) { 3207 VerifyArchiveOopClosure checkOop(NULL); 3208 assert(o != NULL, "Should not be here for NULL oops"); 3209 o->oop_iterate_no_header(&checkOop); 3210 } 3211 }; 3212 3213 class VerifyRegionClosure: public HeapRegionClosure { 3214 private: 3215 bool _par; 3216 VerifyOption _vo; 3217 bool _failures; 3218 public: 3219 // _vo == UsePrevMarking -> use "prev" marking information, 3220 // _vo == UseNextMarking -> use "next" marking information, 3221 // _vo == UseMarkWord -> use mark word from object header. 3222 VerifyRegionClosure(bool par, VerifyOption vo) 3223 : _par(par), 3224 _vo(vo), 3225 _failures(false) {} 3226 3227 bool failures() { 3228 return _failures; 3229 } 3230 3231 bool doHeapRegion(HeapRegion* r) { 3232 // For archive regions, verify there are no heap pointers to 3233 // non-pinned regions. For all others, verify liveness info. 3234 if (r->is_archive()) { 3235 VerifyArchiveRegionClosure verify_oop_pointers(r); 3236 r->object_iterate(&verify_oop_pointers); 3237 return true; 3238 } 3239 if (!r->is_continues_humongous()) { 3240 bool failures = false; 3241 r->verify(_vo, &failures); 3242 if (failures) { 3243 _failures = true; 3244 } else { 3245 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3246 r->object_iterate(¬_dead_yet_cl); 3247 if (_vo != VerifyOption_G1UseNextMarking) { 3248 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3249 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] " 3250 "max_live_bytes " SIZE_FORMAT " " 3251 "< calculated " SIZE_FORMAT, 3252 p2i(r->bottom()), p2i(r->end()), 3253 r->max_live_bytes(), 3254 not_dead_yet_cl.live_bytes()); 3255 _failures = true; 3256 } 3257 } else { 3258 // When vo == UseNextMarking we cannot currently do a sanity 3259 // check on the live bytes as the calculation has not been 3260 // finalized yet. 3261 } 3262 } 3263 } 3264 return false; // stop the region iteration if we hit a failure 3265 } 3266 }; 3267 3268 // This is the task used for parallel verification of the heap regions 3269 3270 class G1ParVerifyTask: public AbstractGangTask { 3271 private: 3272 G1CollectedHeap* _g1h; 3273 VerifyOption _vo; 3274 bool _failures; 3275 HeapRegionClaimer _hrclaimer; 3276 3277 public: 3278 // _vo == UsePrevMarking -> use "prev" marking information, 3279 // _vo == UseNextMarking -> use "next" marking information, 3280 // _vo == UseMarkWord -> use mark word from object header. 3281 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3282 AbstractGangTask("Parallel verify task"), 3283 _g1h(g1h), 3284 _vo(vo), 3285 _failures(false), 3286 _hrclaimer(g1h->workers()->active_workers()) {} 3287 3288 bool failures() { 3289 return _failures; 3290 } 3291 3292 void work(uint worker_id) { 3293 HandleMark hm; 3294 VerifyRegionClosure blk(true, _vo); 3295 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer); 3296 if (blk.failures()) { 3297 _failures = true; 3298 } 3299 } 3300 }; 3301 3302 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3303 if (SafepointSynchronize::is_at_safepoint()) { 3304 assert(Thread::current()->is_VM_thread(), 3305 "Expected to be executed serially by the VM thread at this point"); 3306 3307 if (!silent) { gclog_or_tty->print("Roots "); } 3308 VerifyRootsClosure rootsCl(vo); 3309 VerifyKlassClosure klassCl(this, &rootsCl); 3310 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); 3311 3312 // We apply the relevant closures to all the oops in the 3313 // system dictionary, class loader data graph, the string table 3314 // and the nmethods in the code cache. 3315 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3316 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3317 3318 { 3319 G1RootProcessor root_processor(this, 1); 3320 root_processor.process_all_roots(&rootsCl, 3321 &cldCl, 3322 &blobsCl); 3323 } 3324 3325 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3326 3327 if (vo != VerifyOption_G1UseMarkWord) { 3328 // If we're verifying during a full GC then the region sets 3329 // will have been torn down at the start of the GC. Therefore 3330 // verifying the region sets will fail. So we only verify 3331 // the region sets when not in a full GC. 3332 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3333 verify_region_sets(); 3334 } 3335 3336 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3337 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3338 3339 G1ParVerifyTask task(this, vo); 3340 workers()->run_task(&task); 3341 if (task.failures()) { 3342 failures = true; 3343 } 3344 3345 } else { 3346 VerifyRegionClosure blk(false, vo); 3347 heap_region_iterate(&blk); 3348 if (blk.failures()) { 3349 failures = true; 3350 } 3351 } 3352 3353 if (G1StringDedup::is_enabled()) { 3354 if (!silent) gclog_or_tty->print("StrDedup "); 3355 G1StringDedup::verify(); 3356 } 3357 3358 if (failures) { 3359 gclog_or_tty->print_cr("Heap:"); 3360 // It helps to have the per-region information in the output to 3361 // help us track down what went wrong. This is why we call 3362 // print_extended_on() instead of print_on(). 3363 print_extended_on(gclog_or_tty); 3364 gclog_or_tty->cr(); 3365 gclog_or_tty->flush(); 3366 } 3367 guarantee(!failures, "there should not have been any failures"); 3368 } else { 3369 if (!silent) { 3370 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3371 if (G1StringDedup::is_enabled()) { 3372 gclog_or_tty->print(", StrDedup"); 3373 } 3374 gclog_or_tty->print(") "); 3375 } 3376 } 3377 } 3378 3379 void G1CollectedHeap::verify(bool silent) { 3380 verify(silent, VerifyOption_G1UsePrevMarking); 3381 } 3382 3383 double G1CollectedHeap::verify(bool guard, const char* msg) { 3384 double verify_time_ms = 0.0; 3385 3386 if (guard && total_collections() >= VerifyGCStartAt) { 3387 double verify_start = os::elapsedTime(); 3388 HandleMark hm; // Discard invalid handles created during verification 3389 prepare_for_verify(); 3390 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3391 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3392 } 3393 3394 return verify_time_ms; 3395 } 3396 3397 void G1CollectedHeap::verify_before_gc() { 3398 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3399 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3400 } 3401 3402 void G1CollectedHeap::verify_after_gc() { 3403 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3404 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3405 } 3406 3407 class PrintRegionClosure: public HeapRegionClosure { 3408 outputStream* _st; 3409 public: 3410 PrintRegionClosure(outputStream* st) : _st(st) {} 3411 bool doHeapRegion(HeapRegion* r) { 3412 r->print_on(_st); 3413 return false; 3414 } 3415 }; 3416 3417 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3418 const HeapRegion* hr, 3419 const VerifyOption vo) const { 3420 switch (vo) { 3421 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3422 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3423 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive(); 3424 default: ShouldNotReachHere(); 3425 } 3426 return false; // keep some compilers happy 3427 } 3428 3429 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3430 const VerifyOption vo) const { 3431 switch (vo) { 3432 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3433 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3434 case VerifyOption_G1UseMarkWord: { 3435 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj); 3436 return !obj->is_gc_marked() && !hr->is_archive(); 3437 } 3438 default: ShouldNotReachHere(); 3439 } 3440 return false; // keep some compilers happy 3441 } 3442 3443 void G1CollectedHeap::print_on(outputStream* st) const { 3444 st->print(" %-20s", "garbage-first heap"); 3445 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3446 capacity()/K, used_unlocked()/K); 3447 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")", 3448 p2i(_hrm.reserved().start()), 3449 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords), 3450 p2i(_hrm.reserved().end())); 3451 st->cr(); 3452 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3453 uint young_regions = _young_list->length(); 3454 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3455 (size_t) young_regions * HeapRegion::GrainBytes / K); 3456 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3457 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3458 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3459 st->cr(); 3460 MetaspaceAux::print_on(st); 3461 } 3462 3463 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3464 print_on(st); 3465 3466 // Print the per-region information. 3467 st->cr(); 3468 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, " 3469 "HS=humongous(starts), HC=humongous(continues), " 3470 "CS=collection set, F=free, A=archive, TS=gc time stamp, " 3471 "PTAMS=previous top-at-mark-start, " 3472 "NTAMS=next top-at-mark-start)"); 3473 PrintRegionClosure blk(st); 3474 heap_region_iterate(&blk); 3475 } 3476 3477 void G1CollectedHeap::print_on_error(outputStream* st) const { 3478 this->CollectedHeap::print_on_error(st); 3479 3480 if (_cm != NULL) { 3481 st->cr(); 3482 _cm->print_on_error(st); 3483 } 3484 } 3485 3486 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3487 workers()->print_worker_threads_on(st); 3488 _cmThread->print_on(st); 3489 st->cr(); 3490 _cm->print_worker_threads_on(st); 3491 _cg1r->print_worker_threads_on(st); 3492 if (G1StringDedup::is_enabled()) { 3493 G1StringDedup::print_worker_threads_on(st); 3494 } 3495 } 3496 3497 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3498 workers()->threads_do(tc); 3499 tc->do_thread(_cmThread); 3500 _cg1r->threads_do(tc); 3501 if (G1StringDedup::is_enabled()) { 3502 G1StringDedup::threads_do(tc); 3503 } 3504 } 3505 3506 void G1CollectedHeap::print_tracing_info() const { 3507 // We'll overload this to mean "trace GC pause statistics." 3508 if (TraceYoungGenTime || TraceOldGenTime) { 3509 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3510 // to that. 3511 g1_policy()->print_tracing_info(); 3512 } 3513 if (G1SummarizeRSetStats) { 3514 g1_rem_set()->print_summary_info(); 3515 } 3516 if (G1SummarizeConcMark) { 3517 concurrent_mark()->print_summary_info(); 3518 } 3519 g1_policy()->print_yg_surv_rate_info(); 3520 } 3521 3522 #ifndef PRODUCT 3523 // Helpful for debugging RSet issues. 3524 3525 class PrintRSetsClosure : public HeapRegionClosure { 3526 private: 3527 const char* _msg; 3528 size_t _occupied_sum; 3529 3530 public: 3531 bool doHeapRegion(HeapRegion* r) { 3532 HeapRegionRemSet* hrrs = r->rem_set(); 3533 size_t occupied = hrrs->occupied(); 3534 _occupied_sum += occupied; 3535 3536 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT, 3537 HR_FORMAT_PARAMS(r)); 3538 if (occupied == 0) { 3539 gclog_or_tty->print_cr(" RSet is empty"); 3540 } else { 3541 hrrs->print(); 3542 } 3543 gclog_or_tty->print_cr("----------"); 3544 return false; 3545 } 3546 3547 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3548 gclog_or_tty->cr(); 3549 gclog_or_tty->print_cr("========================================"); 3550 gclog_or_tty->print_cr("%s", msg); 3551 gclog_or_tty->cr(); 3552 } 3553 3554 ~PrintRSetsClosure() { 3555 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 3556 gclog_or_tty->print_cr("========================================"); 3557 gclog_or_tty->cr(); 3558 } 3559 }; 3560 3561 void G1CollectedHeap::print_cset_rsets() { 3562 PrintRSetsClosure cl("Printing CSet RSets"); 3563 collection_set_iterate(&cl); 3564 } 3565 3566 void G1CollectedHeap::print_all_rsets() { 3567 PrintRSetsClosure cl("Printing All RSets");; 3568 heap_region_iterate(&cl); 3569 } 3570 #endif // PRODUCT 3571 3572 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 3573 YoungList* young_list = heap()->young_list(); 3574 3575 size_t eden_used_bytes = young_list->eden_used_bytes(); 3576 size_t survivor_used_bytes = young_list->survivor_used_bytes(); 3577 3578 size_t eden_capacity_bytes = 3579 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 3580 3581 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 3582 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes); 3583 } 3584 3585 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 3586 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 3587 gc_tracer->report_gc_heap_summary(when, heap_summary); 3588 3589 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 3590 gc_tracer->report_metaspace_summary(when, metaspace_summary); 3591 } 3592 3593 3594 G1CollectedHeap* G1CollectedHeap::heap() { 3595 CollectedHeap* heap = Universe::heap(); 3596 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 3597 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); 3598 return (G1CollectedHeap*)heap; 3599 } 3600 3601 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3602 // always_do_update_barrier = false; 3603 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3604 // Fill TLAB's and such 3605 accumulate_statistics_all_tlabs(); 3606 ensure_parsability(true); 3607 3608 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3609 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3610 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3611 } 3612 } 3613 3614 void G1CollectedHeap::gc_epilogue(bool full) { 3615 3616 if (G1SummarizeRSetStats && 3617 (G1SummarizeRSetStatsPeriod > 0) && 3618 // we are at the end of the GC. Total collections has already been increased. 3619 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3620 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3621 } 3622 3623 // FIXME: what is this about? 3624 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3625 // is set. 3626 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3627 "derived pointer present")); 3628 // always_do_update_barrier = true; 3629 3630 resize_all_tlabs(); 3631 allocation_context_stats().update(full); 3632 3633 // We have just completed a GC. Update the soft reference 3634 // policy with the new heap occupancy 3635 Universe::update_heap_info_at_gc(); 3636 } 3637 3638 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3639 uint gc_count_before, 3640 bool* succeeded, 3641 GCCause::Cause gc_cause) { 3642 assert_heap_not_locked_and_not_at_safepoint(); 3643 g1_policy()->record_stop_world_start(); 3644 VM_G1IncCollectionPause op(gc_count_before, 3645 word_size, 3646 false, /* should_initiate_conc_mark */ 3647 g1_policy()->max_pause_time_ms(), 3648 gc_cause); 3649 3650 op.set_allocation_context(AllocationContext::current()); 3651 VMThread::execute(&op); 3652 3653 HeapWord* result = op.result(); 3654 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3655 assert(result == NULL || ret_succeeded, 3656 "the result should be NULL if the VM did not succeed"); 3657 *succeeded = ret_succeeded; 3658 3659 assert_heap_not_locked(); 3660 return result; 3661 } 3662 3663 void 3664 G1CollectedHeap::doConcurrentMark() { 3665 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3666 if (!_cmThread->in_progress()) { 3667 _cmThread->set_started(); 3668 CGC_lock->notify(); 3669 } 3670 } 3671 3672 size_t G1CollectedHeap::pending_card_num() { 3673 size_t extra_cards = 0; 3674 JavaThread *curr = Threads::first(); 3675 while (curr != NULL) { 3676 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3677 extra_cards += dcq.size(); 3678 curr = curr->next(); 3679 } 3680 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3681 size_t buffer_size = dcqs.buffer_size(); 3682 size_t buffer_num = dcqs.completed_buffers_num(); 3683 3684 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3685 // in bytes - not the number of 'entries'. We need to convert 3686 // into a number of cards. 3687 return (buffer_size * buffer_num + extra_cards) / oopSize; 3688 } 3689 3690 size_t G1CollectedHeap::cards_scanned() { 3691 return g1_rem_set()->cardsScanned(); 3692 } 3693 3694 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 3695 private: 3696 size_t _total_humongous; 3697 size_t _candidate_humongous; 3698 3699 DirtyCardQueue _dcq; 3700 3701 // We don't nominate objects with many remembered set entries, on 3702 // the assumption that such objects are likely still live. 3703 bool is_remset_small(HeapRegion* region) const { 3704 HeapRegionRemSet* const rset = region->rem_set(); 3705 return G1EagerReclaimHumongousObjectsWithStaleRefs 3706 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) 3707 : rset->is_empty(); 3708 } 3709 3710 bool is_typeArray_region(HeapRegion* region) const { 3711 return oop(region->bottom())->is_typeArray(); 3712 } 3713 3714 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { 3715 assert(region->is_starts_humongous(), "Must start a humongous object"); 3716 3717 // Candidate selection must satisfy the following constraints 3718 // while concurrent marking is in progress: 3719 // 3720 // * In order to maintain SATB invariants, an object must not be 3721 // reclaimed if it was allocated before the start of marking and 3722 // has not had its references scanned. Such an object must have 3723 // its references (including type metadata) scanned to ensure no 3724 // live objects are missed by the marking process. Objects 3725 // allocated after the start of concurrent marking don't need to 3726 // be scanned. 3727 // 3728 // * An object must not be reclaimed if it is on the concurrent 3729 // mark stack. Objects allocated after the start of concurrent 3730 // marking are never pushed on the mark stack. 3731 // 3732 // Nominating only objects allocated after the start of concurrent 3733 // marking is sufficient to meet both constraints. This may miss 3734 // some objects that satisfy the constraints, but the marking data 3735 // structures don't support efficiently performing the needed 3736 // additional tests or scrubbing of the mark stack. 3737 // 3738 // However, we presently only nominate is_typeArray() objects. 3739 // A humongous object containing references induces remembered 3740 // set entries on other regions. In order to reclaim such an 3741 // object, those remembered sets would need to be cleaned up. 3742 // 3743 // We also treat is_typeArray() objects specially, allowing them 3744 // to be reclaimed even if allocated before the start of 3745 // concurrent mark. For this we rely on mark stack insertion to 3746 // exclude is_typeArray() objects, preventing reclaiming an object 3747 // that is in the mark stack. We also rely on the metadata for 3748 // such objects to be built-in and so ensured to be kept live. 3749 // Frequent allocation and drop of large binary blobs is an 3750 // important use case for eager reclaim, and this special handling 3751 // may reduce needed headroom. 3752 3753 return is_typeArray_region(region) && is_remset_small(region); 3754 } 3755 3756 public: 3757 RegisterHumongousWithInCSetFastTestClosure() 3758 : _total_humongous(0), 3759 _candidate_humongous(0), 3760 _dcq(&JavaThread::dirty_card_queue_set()) { 3761 } 3762 3763 virtual bool doHeapRegion(HeapRegion* r) { 3764 if (!r->is_starts_humongous()) { 3765 return false; 3766 } 3767 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3768 3769 bool is_candidate = humongous_region_is_candidate(g1h, r); 3770 uint rindex = r->hrm_index(); 3771 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 3772 if (is_candidate) { 3773 _candidate_humongous++; 3774 g1h->register_humongous_region_with_cset(rindex); 3775 // Is_candidate already filters out humongous object with large remembered sets. 3776 // If we have a humongous object with a few remembered sets, we simply flush these 3777 // remembered set entries into the DCQS. That will result in automatic 3778 // re-evaluation of their remembered set entries during the following evacuation 3779 // phase. 3780 if (!r->rem_set()->is_empty()) { 3781 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 3782 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 3783 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); 3784 HeapRegionRemSetIterator hrrs(r->rem_set()); 3785 size_t card_index; 3786 while (hrrs.has_next(card_index)) { 3787 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); 3788 // The remembered set might contain references to already freed 3789 // regions. Filter out such entries to avoid failing card table 3790 // verification. 3791 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) { 3792 if (*card_ptr != CardTableModRefBS::dirty_card_val()) { 3793 *card_ptr = CardTableModRefBS::dirty_card_val(); 3794 _dcq.enqueue(card_ptr); 3795 } 3796 } 3797 } 3798 r->rem_set()->clear_locked(); 3799 } 3800 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 3801 } 3802 _total_humongous++; 3803 3804 return false; 3805 } 3806 3807 size_t total_humongous() const { return _total_humongous; } 3808 size_t candidate_humongous() const { return _candidate_humongous; } 3809 3810 void flush_rem_set_entries() { _dcq.flush(); } 3811 }; 3812 3813 void G1CollectedHeap::register_humongous_regions_with_cset() { 3814 if (!G1EagerReclaimHumongousObjects) { 3815 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 3816 return; 3817 } 3818 double time = os::elapsed_counter(); 3819 3820 // Collect reclaim candidate information and register candidates with cset. 3821 RegisterHumongousWithInCSetFastTestClosure cl; 3822 heap_region_iterate(&cl); 3823 3824 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 3825 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 3826 cl.total_humongous(), 3827 cl.candidate_humongous()); 3828 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 3829 3830 // Finally flush all remembered set entries to re-check into the global DCQS. 3831 cl.flush_rem_set_entries(); 3832 } 3833 3834 void 3835 G1CollectedHeap::setup_surviving_young_words() { 3836 assert(_surviving_young_words == NULL, "pre-condition"); 3837 uint array_length = g1_policy()->young_cset_region_length(); 3838 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3839 if (_surviving_young_words == NULL) { 3840 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3841 "Not enough space for young surv words summary."); 3842 } 3843 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3844 #ifdef ASSERT 3845 for (uint i = 0; i < array_length; ++i) { 3846 assert( _surviving_young_words[i] == 0, "memset above" ); 3847 } 3848 #endif // !ASSERT 3849 } 3850 3851 void 3852 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3853 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3854 uint array_length = g1_policy()->young_cset_region_length(); 3855 for (uint i = 0; i < array_length; ++i) { 3856 _surviving_young_words[i] += surv_young_words[i]; 3857 } 3858 } 3859 3860 void 3861 G1CollectedHeap::cleanup_surviving_young_words() { 3862 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3863 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words); 3864 _surviving_young_words = NULL; 3865 } 3866 3867 #ifdef ASSERT 3868 class VerifyCSetClosure: public HeapRegionClosure { 3869 public: 3870 bool doHeapRegion(HeapRegion* hr) { 3871 // Here we check that the CSet region's RSet is ready for parallel 3872 // iteration. The fields that we'll verify are only manipulated 3873 // when the region is part of a CSet and is collected. Afterwards, 3874 // we reset these fields when we clear the region's RSet (when the 3875 // region is freed) so they are ready when the region is 3876 // re-allocated. The only exception to this is if there's an 3877 // evacuation failure and instead of freeing the region we leave 3878 // it in the heap. In that case, we reset these fields during 3879 // evacuation failure handling. 3880 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3881 3882 // Here's a good place to add any other checks we'd like to 3883 // perform on CSet regions. 3884 return false; 3885 } 3886 }; 3887 #endif // ASSERT 3888 3889 uint G1CollectedHeap::num_task_queues() const { 3890 return _task_queues->size(); 3891 } 3892 3893 #if TASKQUEUE_STATS 3894 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3895 st->print_raw_cr("GC Task Stats"); 3896 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3897 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3898 } 3899 3900 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3901 print_taskqueue_stats_hdr(st); 3902 3903 TaskQueueStats totals; 3904 const uint n = num_task_queues(); 3905 for (uint i = 0; i < n; ++i) { 3906 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 3907 totals += task_queue(i)->stats; 3908 } 3909 st->print_raw("tot "); totals.print(st); st->cr(); 3910 3911 DEBUG_ONLY(totals.verify()); 3912 } 3913 3914 void G1CollectedHeap::reset_taskqueue_stats() { 3915 const uint n = num_task_queues(); 3916 for (uint i = 0; i < n; ++i) { 3917 task_queue(i)->stats.reset(); 3918 } 3919 } 3920 #endif // TASKQUEUE_STATS 3921 3922 void G1CollectedHeap::log_gc_header() { 3923 if (!G1Log::fine()) { 3924 return; 3925 } 3926 3927 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id()); 3928 3929 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3930 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)") 3931 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3932 3933 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3934 } 3935 3936 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3937 if (!G1Log::fine()) { 3938 return; 3939 } 3940 3941 if (G1Log::finer()) { 3942 if (evacuation_failed()) { 3943 gclog_or_tty->print(" (to-space exhausted)"); 3944 } 3945 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3946 g1_policy()->phase_times()->note_gc_end(); 3947 g1_policy()->phase_times()->print(pause_time_sec); 3948 g1_policy()->print_detailed_heap_transition(); 3949 } else { 3950 if (evacuation_failed()) { 3951 gclog_or_tty->print("--"); 3952 } 3953 g1_policy()->print_heap_transition(); 3954 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3955 } 3956 gclog_or_tty->flush(); 3957 } 3958 3959 void G1CollectedHeap::wait_for_root_region_scanning() { 3960 double scan_wait_start = os::elapsedTime(); 3961 // We have to wait until the CM threads finish scanning the 3962 // root regions as it's the only way to ensure that all the 3963 // objects on them have been correctly scanned before we start 3964 // moving them during the GC. 3965 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3966 double wait_time_ms = 0.0; 3967 if (waited) { 3968 double scan_wait_end = os::elapsedTime(); 3969 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3970 } 3971 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3972 } 3973 3974 bool 3975 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3976 assert_at_safepoint(true /* should_be_vm_thread */); 3977 guarantee(!is_gc_active(), "collection is not reentrant"); 3978 3979 if (GC_locker::check_active_before_gc()) { 3980 return false; 3981 } 3982 3983 _gc_timer_stw->register_gc_start(); 3984 3985 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3986 3987 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3988 ResourceMark rm; 3989 3990 wait_for_root_region_scanning(); 3991 3992 G1Log::update_level(); 3993 print_heap_before_gc(); 3994 trace_heap_before_gc(_gc_tracer_stw); 3995 3996 verify_region_sets_optional(); 3997 verify_dirty_young_regions(); 3998 3999 // This call will decide whether this pause is an initial-mark 4000 // pause. If it is, during_initial_mark_pause() will return true 4001 // for the duration of this pause. 4002 g1_policy()->decide_on_conc_mark_initiation(); 4003 4004 // We do not allow initial-mark to be piggy-backed on a mixed GC. 4005 assert(!collector_state()->during_initial_mark_pause() || 4006 collector_state()->gcs_are_young(), "sanity"); 4007 4008 // We also do not allow mixed GCs during marking. 4009 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity"); 4010 4011 // Record whether this pause is an initial mark. When the current 4012 // thread has completed its logging output and it's safe to signal 4013 // the CM thread, the flag's value in the policy has been reset. 4014 bool should_start_conc_mark = collector_state()->during_initial_mark_pause(); 4015 4016 // Inner scope for scope based logging, timers, and stats collection 4017 { 4018 EvacuationInfo evacuation_info; 4019 4020 if (collector_state()->during_initial_mark_pause()) { 4021 // We are about to start a marking cycle, so we increment the 4022 // full collection counter. 4023 increment_old_marking_cycles_started(); 4024 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 4025 } 4026 4027 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 4028 4029 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 4030 4031 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 4032 workers()->active_workers(), 4033 Threads::number_of_non_daemon_threads()); 4034 workers()->set_active_workers(active_workers); 4035 4036 double pause_start_sec = os::elapsedTime(); 4037 g1_policy()->phase_times()->note_gc_start(active_workers, collector_state()->mark_in_progress()); 4038 log_gc_header(); 4039 4040 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 4041 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 4042 4043 // If the secondary_free_list is not empty, append it to the 4044 // free_list. No need to wait for the cleanup operation to finish; 4045 // the region allocation code will check the secondary_free_list 4046 // and wait if necessary. If the G1StressConcRegionFreeing flag is 4047 // set, skip this step so that the region allocation code has to 4048 // get entries from the secondary_free_list. 4049 if (!G1StressConcRegionFreeing) { 4050 append_secondary_free_list_if_not_empty_with_lock(); 4051 } 4052 4053 assert(check_young_list_well_formed(), "young list should be well formed"); 4054 4055 // Don't dynamically change the number of GC threads this early. A value of 4056 // 0 is used to indicate serial work. When parallel work is done, 4057 // it will be set. 4058 4059 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 4060 IsGCActiveMark x; 4061 4062 gc_prologue(false); 4063 increment_total_collections(false /* full gc */); 4064 increment_gc_time_stamp(); 4065 4066 verify_before_gc(); 4067 4068 check_bitmaps("GC Start"); 4069 4070 COMPILER2_PRESENT(DerivedPointerTable::clear()); 4071 4072 // Please see comment in g1CollectedHeap.hpp and 4073 // G1CollectedHeap::ref_processing_init() to see how 4074 // reference processing currently works in G1. 4075 4076 // Enable discovery in the STW reference processor 4077 ref_processor_stw()->enable_discovery(); 4078 4079 { 4080 // We want to temporarily turn off discovery by the 4081 // CM ref processor, if necessary, and turn it back on 4082 // on again later if we do. Using a scoped 4083 // NoRefDiscovery object will do this. 4084 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 4085 4086 // Forget the current alloc region (we might even choose it to be part 4087 // of the collection set!). 4088 _allocator->release_mutator_alloc_region(); 4089 4090 // We should call this after we retire the mutator alloc 4091 // region(s) so that all the ALLOC / RETIRE events are generated 4092 // before the start GC event. 4093 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 4094 4095 // This timing is only used by the ergonomics to handle our pause target. 4096 // It is unclear why this should not include the full pause. We will 4097 // investigate this in CR 7178365. 4098 // 4099 // Preserving the old comment here if that helps the investigation: 4100 // 4101 // The elapsed time induced by the start time below deliberately elides 4102 // the possible verification above. 4103 double sample_start_time_sec = os::elapsedTime(); 4104 4105 #if YOUNG_LIST_VERBOSE 4106 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 4107 _young_list->print(); 4108 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4109 #endif // YOUNG_LIST_VERBOSE 4110 4111 g1_policy()->record_collection_pause_start(sample_start_time_sec); 4112 4113 #if YOUNG_LIST_VERBOSE 4114 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 4115 _young_list->print(); 4116 #endif // YOUNG_LIST_VERBOSE 4117 4118 if (collector_state()->during_initial_mark_pause()) { 4119 concurrent_mark()->checkpointRootsInitialPre(); 4120 } 4121 4122 #if YOUNG_LIST_VERBOSE 4123 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 4124 _young_list->print(); 4125 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4126 #endif // YOUNG_LIST_VERBOSE 4127 4128 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 4129 4130 register_humongous_regions_with_cset(); 4131 4132 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table."); 4133 4134 _cm->note_start_of_gc(); 4135 // We call this after finalize_cset() to 4136 // ensure that the CSet has been finalized. 4137 _cm->verify_no_cset_oops(); 4138 4139 if (_hr_printer.is_active()) { 4140 HeapRegion* hr = g1_policy()->collection_set(); 4141 while (hr != NULL) { 4142 _hr_printer.cset(hr); 4143 hr = hr->next_in_collection_set(); 4144 } 4145 } 4146 4147 #ifdef ASSERT 4148 VerifyCSetClosure cl; 4149 collection_set_iterate(&cl); 4150 #endif // ASSERT 4151 4152 setup_surviving_young_words(); 4153 4154 // Initialize the GC alloc regions. 4155 _allocator->init_gc_alloc_regions(evacuation_info); 4156 4157 // Actually do the work... 4158 evacuate_collection_set(evacuation_info); 4159 4160 free_collection_set(g1_policy()->collection_set(), evacuation_info); 4161 4162 eagerly_reclaim_humongous_regions(); 4163 4164 g1_policy()->clear_collection_set(); 4165 4166 cleanup_surviving_young_words(); 4167 4168 // Start a new incremental collection set for the next pause. 4169 g1_policy()->start_incremental_cset_building(); 4170 4171 clear_cset_fast_test(); 4172 4173 _young_list->reset_sampled_info(); 4174 4175 // Don't check the whole heap at this point as the 4176 // GC alloc regions from this pause have been tagged 4177 // as survivors and moved on to the survivor list. 4178 // Survivor regions will fail the !is_young() check. 4179 assert(check_young_list_empty(false /* check_heap */), 4180 "young list should be empty"); 4181 4182 #if YOUNG_LIST_VERBOSE 4183 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 4184 _young_list->print(); 4185 #endif // YOUNG_LIST_VERBOSE 4186 4187 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 4188 _young_list->first_survivor_region(), 4189 _young_list->last_survivor_region()); 4190 4191 _young_list->reset_auxilary_lists(); 4192 4193 if (evacuation_failed()) { 4194 set_used(recalculate_used()); 4195 if (_archive_allocator != NULL) { 4196 _archive_allocator->clear_used(); 4197 } 4198 for (uint i = 0; i < ParallelGCThreads; i++) { 4199 if (_evacuation_failed_info_array[i].has_failed()) { 4200 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 4201 } 4202 } 4203 } else { 4204 // The "used" of the the collection set have already been subtracted 4205 // when they were freed. Add in the bytes evacuated. 4206 increase_used(g1_policy()->bytes_copied_during_gc()); 4207 } 4208 4209 if (collector_state()->during_initial_mark_pause()) { 4210 // We have to do this before we notify the CM threads that 4211 // they can start working to make sure that all the 4212 // appropriate initialization is done on the CM object. 4213 concurrent_mark()->checkpointRootsInitialPost(); 4214 collector_state()->set_mark_in_progress(true); 4215 // Note that we don't actually trigger the CM thread at 4216 // this point. We do that later when we're sure that 4217 // the current thread has completed its logging output. 4218 } 4219 4220 allocate_dummy_regions(); 4221 4222 #if YOUNG_LIST_VERBOSE 4223 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 4224 _young_list->print(); 4225 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4226 #endif // YOUNG_LIST_VERBOSE 4227 4228 _allocator->init_mutator_alloc_region(); 4229 4230 { 4231 size_t expand_bytes = g1_policy()->expansion_amount(); 4232 if (expand_bytes > 0) { 4233 size_t bytes_before = capacity(); 4234 // No need for an ergo verbose message here, 4235 // expansion_amount() does this when it returns a value > 0. 4236 if (!expand(expand_bytes)) { 4237 // We failed to expand the heap. Cannot do anything about it. 4238 } 4239 } 4240 } 4241 4242 // We redo the verification but now wrt to the new CSet which 4243 // has just got initialized after the previous CSet was freed. 4244 _cm->verify_no_cset_oops(); 4245 _cm->note_end_of_gc(); 4246 4247 // This timing is only used by the ergonomics to handle our pause target. 4248 // It is unclear why this should not include the full pause. We will 4249 // investigate this in CR 7178365. 4250 double sample_end_time_sec = os::elapsedTime(); 4251 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 4252 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 4253 4254 MemoryService::track_memory_usage(); 4255 4256 // In prepare_for_verify() below we'll need to scan the deferred 4257 // update buffers to bring the RSets up-to-date if 4258 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4259 // the update buffers we'll probably need to scan cards on the 4260 // regions we just allocated to (i.e., the GC alloc 4261 // regions). However, during the last GC we called 4262 // set_saved_mark() on all the GC alloc regions, so card 4263 // scanning might skip the [saved_mark_word()...top()] area of 4264 // those regions (i.e., the area we allocated objects into 4265 // during the last GC). But it shouldn't. Given that 4266 // saved_mark_word() is conditional on whether the GC time stamp 4267 // on the region is current or not, by incrementing the GC time 4268 // stamp here we invalidate all the GC time stamps on all the 4269 // regions and saved_mark_word() will simply return top() for 4270 // all the regions. This is a nicer way of ensuring this rather 4271 // than iterating over the regions and fixing them. In fact, the 4272 // GC time stamp increment here also ensures that 4273 // saved_mark_word() will return top() between pauses, i.e., 4274 // during concurrent refinement. So we don't need the 4275 // is_gc_active() check to decided which top to use when 4276 // scanning cards (see CR 7039627). 4277 increment_gc_time_stamp(); 4278 4279 verify_after_gc(); 4280 check_bitmaps("GC End"); 4281 4282 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4283 ref_processor_stw()->verify_no_references_recorded(); 4284 4285 // CM reference discovery will be re-enabled if necessary. 4286 } 4287 4288 // We should do this after we potentially expand the heap so 4289 // that all the COMMIT events are generated before the end GC 4290 // event, and after we retire the GC alloc regions so that all 4291 // RETIRE events are generated before the end GC event. 4292 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4293 4294 #ifdef TRACESPINNING 4295 ParallelTaskTerminator::print_termination_counts(); 4296 #endif 4297 4298 gc_epilogue(false); 4299 } 4300 4301 // Print the remainder of the GC log output. 4302 log_gc_footer(os::elapsedTime() - pause_start_sec); 4303 4304 // It is not yet to safe to tell the concurrent mark to 4305 // start as we have some optional output below. We don't want the 4306 // output from the concurrent mark thread interfering with this 4307 // logging output either. 4308 4309 _hrm.verify_optional(); 4310 verify_region_sets_optional(); 4311 4312 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats()); 4313 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4314 4315 print_heap_after_gc(); 4316 trace_heap_after_gc(_gc_tracer_stw); 4317 4318 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4319 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4320 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4321 // before any GC notifications are raised. 4322 g1mm()->update_sizes(); 4323 4324 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4325 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4326 _gc_timer_stw->register_gc_end(); 4327 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4328 } 4329 // It should now be safe to tell the concurrent mark thread to start 4330 // without its logging output interfering with the logging output 4331 // that came from the pause. 4332 4333 if (should_start_conc_mark) { 4334 // CAUTION: after the doConcurrentMark() call below, 4335 // the concurrent marking thread(s) could be running 4336 // concurrently with us. Make sure that anything after 4337 // this point does not assume that we are the only GC thread 4338 // running. Note: of course, the actual marking work will 4339 // not start until the safepoint itself is released in 4340 // SuspendibleThreadSet::desynchronize(). 4341 doConcurrentMark(); 4342 } 4343 4344 return true; 4345 } 4346 4347 void G1CollectedHeap::remove_self_forwarding_pointers() { 4348 double remove_self_forwards_start = os::elapsedTime(); 4349 4350 G1ParRemoveSelfForwardPtrsTask rsfp_task; 4351 workers()->run_task(&rsfp_task); 4352 4353 // Now restore saved marks, if any. 4354 for (uint i = 0; i < ParallelGCThreads; i++) { 4355 OopAndMarkOopStack& cur = _preserved_objs[i]; 4356 while (!cur.is_empty()) { 4357 OopAndMarkOop elem = cur.pop(); 4358 elem.set_mark(); 4359 } 4360 cur.clear(true); 4361 } 4362 4363 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4364 } 4365 4366 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 4367 if (!_evacuation_failed) { 4368 _evacuation_failed = true; 4369 } 4370 4371 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 4372 4373 // We want to call the "for_promotion_failure" version only in the 4374 // case of a promotion failure. 4375 if (m->must_be_preserved_for_promotion_failure(obj)) { 4376 OopAndMarkOop elem(obj, m); 4377 _preserved_objs[worker_id].push(elem); 4378 } 4379 } 4380 4381 void G1ParCopyHelper::mark_object(oop obj) { 4382 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); 4383 4384 // We know that the object is not moving so it's safe to read its size. 4385 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4386 } 4387 4388 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4389 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4390 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4391 assert(from_obj != to_obj, "should not be self-forwarded"); 4392 4393 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); 4394 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); 4395 4396 // The object might be in the process of being copied by another 4397 // worker so we cannot trust that its to-space image is 4398 // well-formed. So we have to read its size from its from-space 4399 // image which we know should not be changing. 4400 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4401 } 4402 4403 template <class T> 4404 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4405 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4406 _scanned_klass->record_modified_oops(); 4407 } 4408 } 4409 4410 template <G1Barrier barrier, G1Mark do_mark_object> 4411 template <class T> 4412 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4413 T heap_oop = oopDesc::load_heap_oop(p); 4414 4415 if (oopDesc::is_null(heap_oop)) { 4416 return; 4417 } 4418 4419 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4420 4421 assert(_worker_id == _par_scan_state->worker_id(), "sanity"); 4422 4423 const InCSetState state = _g1->in_cset_state(obj); 4424 if (state.is_in_cset()) { 4425 oop forwardee; 4426 markOop m = obj->mark(); 4427 if (m->is_marked()) { 4428 forwardee = (oop) m->decode_pointer(); 4429 } else { 4430 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m); 4431 } 4432 assert(forwardee != NULL, "forwardee should not be NULL"); 4433 oopDesc::encode_store_heap_oop(p, forwardee); 4434 if (do_mark_object != G1MarkNone && forwardee != obj) { 4435 // If the object is self-forwarded we don't need to explicitly 4436 // mark it, the evacuation failure protocol will do so. 4437 mark_forwarded_object(obj, forwardee); 4438 } 4439 4440 if (barrier == G1BarrierKlass) { 4441 do_klass_barrier(p, forwardee); 4442 } 4443 } else { 4444 if (state.is_humongous()) { 4445 _g1->set_humongous_is_live(obj); 4446 } 4447 // The object is not in collection set. If we're a root scanning 4448 // closure during an initial mark pause then attempt to mark the object. 4449 if (do_mark_object == G1MarkFromRoot) { 4450 mark_object(obj); 4451 } 4452 } 4453 } 4454 4455 class G1ParEvacuateFollowersClosure : public VoidClosure { 4456 protected: 4457 G1CollectedHeap* _g1h; 4458 G1ParScanThreadState* _par_scan_state; 4459 RefToScanQueueSet* _queues; 4460 ParallelTaskTerminator* _terminator; 4461 4462 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4463 RefToScanQueueSet* queues() { return _queues; } 4464 ParallelTaskTerminator* terminator() { return _terminator; } 4465 4466 public: 4467 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4468 G1ParScanThreadState* par_scan_state, 4469 RefToScanQueueSet* queues, 4470 ParallelTaskTerminator* terminator) 4471 : _g1h(g1h), _par_scan_state(par_scan_state), 4472 _queues(queues), _terminator(terminator) {} 4473 4474 void do_void(); 4475 4476 private: 4477 inline bool offer_termination(); 4478 }; 4479 4480 bool G1ParEvacuateFollowersClosure::offer_termination() { 4481 G1ParScanThreadState* const pss = par_scan_state(); 4482 pss->start_term_time(); 4483 const bool res = terminator()->offer_termination(); 4484 pss->end_term_time(); 4485 return res; 4486 } 4487 4488 void G1ParEvacuateFollowersClosure::do_void() { 4489 G1ParScanThreadState* const pss = par_scan_state(); 4490 pss->trim_queue(); 4491 do { 4492 pss->steal_and_trim_queue(queues()); 4493 } while (!offer_termination()); 4494 } 4495 4496 class G1KlassScanClosure : public KlassClosure { 4497 G1ParCopyHelper* _closure; 4498 bool _process_only_dirty; 4499 int _count; 4500 public: 4501 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4502 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4503 void do_klass(Klass* klass) { 4504 // If the klass has not been dirtied we know that there's 4505 // no references into the young gen and we can skip it. 4506 if (!_process_only_dirty || klass->has_modified_oops()) { 4507 // Clean the klass since we're going to scavenge all the metadata. 4508 klass->clear_modified_oops(); 4509 4510 // Tell the closure that this klass is the Klass to scavenge 4511 // and is the one to dirty if oops are left pointing into the young gen. 4512 _closure->set_scanned_klass(klass); 4513 4514 klass->oops_do(_closure); 4515 4516 _closure->set_scanned_klass(NULL); 4517 } 4518 _count++; 4519 } 4520 }; 4521 4522 class G1ParTask : public AbstractGangTask { 4523 protected: 4524 G1CollectedHeap* _g1h; 4525 RefToScanQueueSet *_queues; 4526 G1RootProcessor* _root_processor; 4527 ParallelTaskTerminator _terminator; 4528 uint _n_workers; 4529 4530 public: 4531 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 4532 : AbstractGangTask("G1 collection"), 4533 _g1h(g1h), 4534 _queues(task_queues), 4535 _root_processor(root_processor), 4536 _terminator(n_workers, _queues), 4537 _n_workers(n_workers) 4538 {} 4539 4540 RefToScanQueueSet* queues() { return _queues; } 4541 4542 RefToScanQueue *work_queue(int i) { 4543 return queues()->queue(i); 4544 } 4545 4546 ParallelTaskTerminator* terminator() { return &_terminator; } 4547 4548 // Helps out with CLD processing. 4549 // 4550 // During InitialMark we need to: 4551 // 1) Scavenge all CLDs for the young GC. 4552 // 2) Mark all objects directly reachable from strong CLDs. 4553 template <G1Mark do_mark_object> 4554 class G1CLDClosure : public CLDClosure { 4555 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure; 4556 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure; 4557 G1KlassScanClosure _klass_in_cld_closure; 4558 bool _claim; 4559 4560 public: 4561 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure, 4562 bool only_young, bool claim) 4563 : _oop_closure(oop_closure), 4564 _oop_in_klass_closure(oop_closure->g1(), 4565 oop_closure->pss(), 4566 oop_closure->rp()), 4567 _klass_in_cld_closure(&_oop_in_klass_closure, only_young), 4568 _claim(claim) { 4569 4570 } 4571 4572 void do_cld(ClassLoaderData* cld) { 4573 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim); 4574 } 4575 }; 4576 4577 void work(uint worker_id) { 4578 if (worker_id >= _n_workers) return; // no work needed this round 4579 4580 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime()); 4581 4582 { 4583 ResourceMark rm; 4584 HandleMark hm; 4585 4586 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4587 4588 G1ParScanThreadState pss(_g1h, worker_id, rp); 4589 4590 bool only_young = _g1h->collector_state()->gcs_are_young(); 4591 4592 // Non-IM young GC. 4593 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp); 4594 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl, 4595 only_young, // Only process dirty klasses. 4596 false); // No need to claim CLDs. 4597 // IM young GC. 4598 // Strong roots closures. 4599 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp); 4600 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl, 4601 false, // Process all klasses. 4602 true); // Need to claim CLDs. 4603 // Weak roots closures. 4604 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp); 4605 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl, 4606 false, // Process all klasses. 4607 true); // Need to claim CLDs. 4608 4609 OopClosure* strong_root_cl; 4610 OopClosure* weak_root_cl; 4611 CLDClosure* strong_cld_cl; 4612 CLDClosure* weak_cld_cl; 4613 4614 bool trace_metadata = false; 4615 4616 if (_g1h->collector_state()->during_initial_mark_pause()) { 4617 // We also need to mark copied objects. 4618 strong_root_cl = &scan_mark_root_cl; 4619 strong_cld_cl = &scan_mark_cld_cl; 4620 if (ClassUnloadingWithConcurrentMark) { 4621 weak_root_cl = &scan_mark_weak_root_cl; 4622 weak_cld_cl = &scan_mark_weak_cld_cl; 4623 trace_metadata = true; 4624 } else { 4625 weak_root_cl = &scan_mark_root_cl; 4626 weak_cld_cl = &scan_mark_cld_cl; 4627 } 4628 } else { 4629 strong_root_cl = &scan_only_root_cl; 4630 weak_root_cl = &scan_only_root_cl; 4631 strong_cld_cl = &scan_only_cld_cl; 4632 weak_cld_cl = &scan_only_cld_cl; 4633 } 4634 4635 pss.start_strong_roots(); 4636 4637 _root_processor->evacuate_roots(strong_root_cl, 4638 weak_root_cl, 4639 strong_cld_cl, 4640 weak_cld_cl, 4641 trace_metadata, 4642 worker_id); 4643 4644 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4645 _root_processor->scan_remembered_sets(&push_heap_rs_cl, 4646 weak_root_cl, 4647 worker_id); 4648 pss.end_strong_roots(); 4649 4650 { 4651 double start = os::elapsedTime(); 4652 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4653 evac.do_void(); 4654 double elapsed_sec = os::elapsedTime() - start; 4655 double term_sec = pss.term_time(); 4656 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 4657 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 4658 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts()); 4659 } 4660 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4661 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4662 4663 if (PrintTerminationStats) { 4664 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 4665 pss.print_termination_stats(); 4666 } 4667 4668 assert(pss.queue_is_empty(), "should be empty"); 4669 4670 // Close the inner scope so that the ResourceMark and HandleMark 4671 // destructors are executed here and are included as part of the 4672 // "GC Worker Time". 4673 } 4674 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 4675 } 4676 }; 4677 4678 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 4679 private: 4680 BoolObjectClosure* _is_alive; 4681 int _initial_string_table_size; 4682 int _initial_symbol_table_size; 4683 4684 bool _process_strings; 4685 int _strings_processed; 4686 int _strings_removed; 4687 4688 bool _process_symbols; 4689 int _symbols_processed; 4690 int _symbols_removed; 4691 4692 public: 4693 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 4694 AbstractGangTask("String/Symbol Unlinking"), 4695 _is_alive(is_alive), 4696 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 4697 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 4698 4699 _initial_string_table_size = StringTable::the_table()->table_size(); 4700 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 4701 if (process_strings) { 4702 StringTable::clear_parallel_claimed_index(); 4703 } 4704 if (process_symbols) { 4705 SymbolTable::clear_parallel_claimed_index(); 4706 } 4707 } 4708 4709 ~G1StringSymbolTableUnlinkTask() { 4710 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 4711 err_msg("claim value %d after unlink less than initial string table size %d", 4712 StringTable::parallel_claimed_index(), _initial_string_table_size)); 4713 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 4714 err_msg("claim value %d after unlink less than initial symbol table size %d", 4715 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 4716 4717 if (G1TraceStringSymbolTableScrubbing) { 4718 gclog_or_tty->print_cr("Cleaned string and symbol table, " 4719 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, " 4720 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed", 4721 strings_processed(), strings_removed(), 4722 symbols_processed(), symbols_removed()); 4723 } 4724 } 4725 4726 void work(uint worker_id) { 4727 int strings_processed = 0; 4728 int strings_removed = 0; 4729 int symbols_processed = 0; 4730 int symbols_removed = 0; 4731 if (_process_strings) { 4732 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 4733 Atomic::add(strings_processed, &_strings_processed); 4734 Atomic::add(strings_removed, &_strings_removed); 4735 } 4736 if (_process_symbols) { 4737 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 4738 Atomic::add(symbols_processed, &_symbols_processed); 4739 Atomic::add(symbols_removed, &_symbols_removed); 4740 } 4741 } 4742 4743 size_t strings_processed() const { return (size_t)_strings_processed; } 4744 size_t strings_removed() const { return (size_t)_strings_removed; } 4745 4746 size_t symbols_processed() const { return (size_t)_symbols_processed; } 4747 size_t symbols_removed() const { return (size_t)_symbols_removed; } 4748 }; 4749 4750 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { 4751 private: 4752 static Monitor* _lock; 4753 4754 BoolObjectClosure* const _is_alive; 4755 const bool _unloading_occurred; 4756 const uint _num_workers; 4757 4758 // Variables used to claim nmethods. 4759 nmethod* _first_nmethod; 4760 volatile nmethod* _claimed_nmethod; 4761 4762 // The list of nmethods that need to be processed by the second pass. 4763 volatile nmethod* _postponed_list; 4764 volatile uint _num_entered_barrier; 4765 4766 public: 4767 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 4768 _is_alive(is_alive), 4769 _unloading_occurred(unloading_occurred), 4770 _num_workers(num_workers), 4771 _first_nmethod(NULL), 4772 _claimed_nmethod(NULL), 4773 _postponed_list(NULL), 4774 _num_entered_barrier(0) 4775 { 4776 nmethod::increase_unloading_clock(); 4777 // Get first alive nmethod 4778 NMethodIterator iter = NMethodIterator(); 4779 if(iter.next_alive()) { 4780 _first_nmethod = iter.method(); 4781 } 4782 _claimed_nmethod = (volatile nmethod*)_first_nmethod; 4783 } 4784 4785 ~G1CodeCacheUnloadingTask() { 4786 CodeCache::verify_clean_inline_caches(); 4787 4788 CodeCache::set_needs_cache_clean(false); 4789 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 4790 4791 CodeCache::verify_icholder_relocations(); 4792 } 4793 4794 private: 4795 void add_to_postponed_list(nmethod* nm) { 4796 nmethod* old; 4797 do { 4798 old = (nmethod*)_postponed_list; 4799 nm->set_unloading_next(old); 4800 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); 4801 } 4802 4803 void clean_nmethod(nmethod* nm) { 4804 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 4805 4806 if (postponed) { 4807 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 4808 add_to_postponed_list(nm); 4809 } 4810 4811 // Mark that this thread has been cleaned/unloaded. 4812 // After this call, it will be safe to ask if this nmethod was unloaded or not. 4813 nm->set_unloading_clock(nmethod::global_unloading_clock()); 4814 } 4815 4816 void clean_nmethod_postponed(nmethod* nm) { 4817 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 4818 } 4819 4820 static const int MaxClaimNmethods = 16; 4821 4822 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { 4823 nmethod* first; 4824 NMethodIterator last; 4825 4826 do { 4827 *num_claimed_nmethods = 0; 4828 4829 first = (nmethod*)_claimed_nmethod; 4830 last = NMethodIterator(first); 4831 4832 if (first != NULL) { 4833 4834 for (int i = 0; i < MaxClaimNmethods; i++) { 4835 if (!last.next_alive()) { 4836 break; 4837 } 4838 claimed_nmethods[i] = last.method(); 4839 (*num_claimed_nmethods)++; 4840 } 4841 } 4842 4843 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); 4844 } 4845 4846 nmethod* claim_postponed_nmethod() { 4847 nmethod* claim; 4848 nmethod* next; 4849 4850 do { 4851 claim = (nmethod*)_postponed_list; 4852 if (claim == NULL) { 4853 return NULL; 4854 } 4855 4856 next = claim->unloading_next(); 4857 4858 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); 4859 4860 return claim; 4861 } 4862 4863 public: 4864 // Mark that we're done with the first pass of nmethod cleaning. 4865 void barrier_mark(uint worker_id) { 4866 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4867 _num_entered_barrier++; 4868 if (_num_entered_barrier == _num_workers) { 4869 ml.notify_all(); 4870 } 4871 } 4872 4873 // See if we have to wait for the other workers to 4874 // finish their first-pass nmethod cleaning work. 4875 void barrier_wait(uint worker_id) { 4876 if (_num_entered_barrier < _num_workers) { 4877 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 4878 while (_num_entered_barrier < _num_workers) { 4879 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 4880 } 4881 } 4882 } 4883 4884 // Cleaning and unloading of nmethods. Some work has to be postponed 4885 // to the second pass, when we know which nmethods survive. 4886 void work_first_pass(uint worker_id) { 4887 // The first nmethods is claimed by the first worker. 4888 if (worker_id == 0 && _first_nmethod != NULL) { 4889 clean_nmethod(_first_nmethod); 4890 _first_nmethod = NULL; 4891 } 4892 4893 int num_claimed_nmethods; 4894 nmethod* claimed_nmethods[MaxClaimNmethods]; 4895 4896 while (true) { 4897 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 4898 4899 if (num_claimed_nmethods == 0) { 4900 break; 4901 } 4902 4903 for (int i = 0; i < num_claimed_nmethods; i++) { 4904 clean_nmethod(claimed_nmethods[i]); 4905 } 4906 } 4907 } 4908 4909 void work_second_pass(uint worker_id) { 4910 nmethod* nm; 4911 // Take care of postponed nmethods. 4912 while ((nm = claim_postponed_nmethod()) != NULL) { 4913 clean_nmethod_postponed(nm); 4914 } 4915 } 4916 }; 4917 4918 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 4919 4920 class G1KlassCleaningTask : public StackObj { 4921 BoolObjectClosure* _is_alive; 4922 volatile jint _clean_klass_tree_claimed; 4923 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 4924 4925 public: 4926 G1KlassCleaningTask(BoolObjectClosure* is_alive) : 4927 _is_alive(is_alive), 4928 _clean_klass_tree_claimed(0), 4929 _klass_iterator() { 4930 } 4931 4932 private: 4933 bool claim_clean_klass_tree_task() { 4934 if (_clean_klass_tree_claimed) { 4935 return false; 4936 } 4937 4938 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; 4939 } 4940 4941 InstanceKlass* claim_next_klass() { 4942 Klass* klass; 4943 do { 4944 klass =_klass_iterator.next_klass(); 4945 } while (klass != NULL && !klass->oop_is_instance()); 4946 4947 return (InstanceKlass*)klass; 4948 } 4949 4950 public: 4951 4952 void clean_klass(InstanceKlass* ik) { 4953 ik->clean_implementors_list(_is_alive); 4954 ik->clean_method_data(_is_alive); 4955 4956 // G1 specific cleanup work that has 4957 // been moved here to be done in parallel. 4958 ik->clean_dependent_nmethods(); 4959 } 4960 4961 void work() { 4962 ResourceMark rm; 4963 4964 // One worker will clean the subklass/sibling klass tree. 4965 if (claim_clean_klass_tree_task()) { 4966 Klass::clean_subklass_tree(_is_alive); 4967 } 4968 4969 // All workers will help cleaning the classes, 4970 InstanceKlass* klass; 4971 while ((klass = claim_next_klass()) != NULL) { 4972 clean_klass(klass); 4973 } 4974 } 4975 }; 4976 4977 // To minimize the remark pause times, the tasks below are done in parallel. 4978 class G1ParallelCleaningTask : public AbstractGangTask { 4979 private: 4980 G1StringSymbolTableUnlinkTask _string_symbol_task; 4981 G1CodeCacheUnloadingTask _code_cache_task; 4982 G1KlassCleaningTask _klass_cleaning_task; 4983 4984 public: 4985 // The constructor is run in the VMThread. 4986 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : 4987 AbstractGangTask("Parallel Cleaning"), 4988 _string_symbol_task(is_alive, process_strings, process_symbols), 4989 _code_cache_task(num_workers, is_alive, unloading_occurred), 4990 _klass_cleaning_task(is_alive) { 4991 } 4992 4993 // The parallel work done by all worker threads. 4994 void work(uint worker_id) { 4995 // Do first pass of code cache cleaning. 4996 _code_cache_task.work_first_pass(worker_id); 4997 4998 // Let the threads mark that the first pass is done. 4999 _code_cache_task.barrier_mark(worker_id); 5000 5001 // Clean the Strings and Symbols. 5002 _string_symbol_task.work(worker_id); 5003 5004 // Wait for all workers to finish the first code cache cleaning pass. 5005 _code_cache_task.barrier_wait(worker_id); 5006 5007 // Do the second code cache cleaning work, which realize on 5008 // the liveness information gathered during the first pass. 5009 _code_cache_task.work_second_pass(worker_id); 5010 5011 // Clean all klasses that were not unloaded. 5012 _klass_cleaning_task.work(); 5013 } 5014 }; 5015 5016 5017 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, 5018 bool process_strings, 5019 bool process_symbols, 5020 bool class_unloading_occurred) { 5021 uint n_workers = workers()->active_workers(); 5022 5023 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, 5024 n_workers, class_unloading_occurred); 5025 workers()->run_task(&g1_unlink_task); 5026 } 5027 5028 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 5029 bool process_strings, bool process_symbols) { 5030 { 5031 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 5032 workers()->run_task(&g1_unlink_task); 5033 } 5034 5035 if (G1StringDedup::is_enabled()) { 5036 G1StringDedup::unlink(is_alive); 5037 } 5038 } 5039 5040 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 5041 private: 5042 DirtyCardQueueSet* _queue; 5043 public: 5044 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 5045 5046 virtual void work(uint worker_id) { 5047 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times(); 5048 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 5049 5050 RedirtyLoggedCardTableEntryClosure cl; 5051 _queue->par_apply_closure_to_all_completed_buffers(&cl); 5052 5053 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed()); 5054 } 5055 }; 5056 5057 void G1CollectedHeap::redirty_logged_cards() { 5058 double redirty_logged_cards_start = os::elapsedTime(); 5059 5060 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 5061 dirty_card_queue_set().reset_for_par_iteration(); 5062 workers()->run_task(&redirty_task); 5063 5064 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 5065 dcq.merge_bufferlists(&dirty_card_queue_set()); 5066 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 5067 5068 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 5069 } 5070 5071 // Weak Reference Processing support 5072 5073 // An always "is_alive" closure that is used to preserve referents. 5074 // If the object is non-null then it's alive. Used in the preservation 5075 // of referent objects that are pointed to by reference objects 5076 // discovered by the CM ref processor. 5077 class G1AlwaysAliveClosure: public BoolObjectClosure { 5078 G1CollectedHeap* _g1; 5079 public: 5080 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5081 bool do_object_b(oop p) { 5082 if (p != NULL) { 5083 return true; 5084 } 5085 return false; 5086 } 5087 }; 5088 5089 bool G1STWIsAliveClosure::do_object_b(oop p) { 5090 // An object is reachable if it is outside the collection set, 5091 // or is inside and copied. 5092 return !_g1->is_in_cset(p) || p->is_forwarded(); 5093 } 5094 5095 // Non Copying Keep Alive closure 5096 class G1KeepAliveClosure: public OopClosure { 5097 G1CollectedHeap* _g1; 5098 public: 5099 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5100 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 5101 void do_oop(oop* p) { 5102 oop obj = *p; 5103 assert(obj != NULL, "the caller should have filtered out NULL values"); 5104 5105 const InCSetState cset_state = _g1->in_cset_state(obj); 5106 if (!cset_state.is_in_cset_or_humongous()) { 5107 return; 5108 } 5109 if (cset_state.is_in_cset()) { 5110 assert( obj->is_forwarded(), "invariant" ); 5111 *p = obj->forwardee(); 5112 } else { 5113 assert(!obj->is_forwarded(), "invariant" ); 5114 assert(cset_state.is_humongous(), 5115 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value())); 5116 _g1->set_humongous_is_live(obj); 5117 } 5118 } 5119 }; 5120 5121 // Copying Keep Alive closure - can be called from both 5122 // serial and parallel code as long as different worker 5123 // threads utilize different G1ParScanThreadState instances 5124 // and different queues. 5125 5126 class G1CopyingKeepAliveClosure: public OopClosure { 5127 G1CollectedHeap* _g1h; 5128 OopClosure* _copy_non_heap_obj_cl; 5129 G1ParScanThreadState* _par_scan_state; 5130 5131 public: 5132 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 5133 OopClosure* non_heap_obj_cl, 5134 G1ParScanThreadState* pss): 5135 _g1h(g1h), 5136 _copy_non_heap_obj_cl(non_heap_obj_cl), 5137 _par_scan_state(pss) 5138 {} 5139 5140 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 5141 virtual void do_oop( oop* p) { do_oop_work(p); } 5142 5143 template <class T> void do_oop_work(T* p) { 5144 oop obj = oopDesc::load_decode_heap_oop(p); 5145 5146 if (_g1h->is_in_cset_or_humongous(obj)) { 5147 // If the referent object has been forwarded (either copied 5148 // to a new location or to itself in the event of an 5149 // evacuation failure) then we need to update the reference 5150 // field and, if both reference and referent are in the G1 5151 // heap, update the RSet for the referent. 5152 // 5153 // If the referent has not been forwarded then we have to keep 5154 // it alive by policy. Therefore we have copy the referent. 5155 // 5156 // If the reference field is in the G1 heap then we can push 5157 // on the PSS queue. When the queue is drained (after each 5158 // phase of reference processing) the object and it's followers 5159 // will be copied, the reference field set to point to the 5160 // new location, and the RSet updated. Otherwise we need to 5161 // use the the non-heap or metadata closures directly to copy 5162 // the referent object and update the pointer, while avoiding 5163 // updating the RSet. 5164 5165 if (_g1h->is_in_g1_reserved(p)) { 5166 _par_scan_state->push_on_queue(p); 5167 } else { 5168 assert(!Metaspace::contains((const void*)p), 5169 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p))); 5170 _copy_non_heap_obj_cl->do_oop(p); 5171 } 5172 } 5173 } 5174 }; 5175 5176 // Serial drain queue closure. Called as the 'complete_gc' 5177 // closure for each discovered list in some of the 5178 // reference processing phases. 5179 5180 class G1STWDrainQueueClosure: public VoidClosure { 5181 protected: 5182 G1CollectedHeap* _g1h; 5183 G1ParScanThreadState* _par_scan_state; 5184 5185 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5186 5187 public: 5188 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5189 _g1h(g1h), 5190 _par_scan_state(pss) 5191 { } 5192 5193 void do_void() { 5194 G1ParScanThreadState* const pss = par_scan_state(); 5195 pss->trim_queue(); 5196 } 5197 }; 5198 5199 // Parallel Reference Processing closures 5200 5201 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5202 // processing during G1 evacuation pauses. 5203 5204 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5205 private: 5206 G1CollectedHeap* _g1h; 5207 RefToScanQueueSet* _queues; 5208 FlexibleWorkGang* _workers; 5209 uint _active_workers; 5210 5211 public: 5212 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5213 FlexibleWorkGang* workers, 5214 RefToScanQueueSet *task_queues, 5215 uint n_workers) : 5216 _g1h(g1h), 5217 _queues(task_queues), 5218 _workers(workers), 5219 _active_workers(n_workers) 5220 { 5221 assert(n_workers > 0, "shouldn't call this otherwise"); 5222 } 5223 5224 // Executes the given task using concurrent marking worker threads. 5225 virtual void execute(ProcessTask& task); 5226 virtual void execute(EnqueueTask& task); 5227 }; 5228 5229 // Gang task for possibly parallel reference processing 5230 5231 class G1STWRefProcTaskProxy: public AbstractGangTask { 5232 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5233 ProcessTask& _proc_task; 5234 G1CollectedHeap* _g1h; 5235 RefToScanQueueSet *_task_queues; 5236 ParallelTaskTerminator* _terminator; 5237 5238 public: 5239 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5240 G1CollectedHeap* g1h, 5241 RefToScanQueueSet *task_queues, 5242 ParallelTaskTerminator* terminator) : 5243 AbstractGangTask("Process reference objects in parallel"), 5244 _proc_task(proc_task), 5245 _g1h(g1h), 5246 _task_queues(task_queues), 5247 _terminator(terminator) 5248 {} 5249 5250 virtual void work(uint worker_id) { 5251 // The reference processing task executed by a single worker. 5252 ResourceMark rm; 5253 HandleMark hm; 5254 5255 G1STWIsAliveClosure is_alive(_g1h); 5256 5257 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5258 5259 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5260 5261 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5262 5263 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5264 5265 if (_g1h->collector_state()->during_initial_mark_pause()) { 5266 // We also need to mark copied objects. 5267 copy_non_heap_cl = ©_mark_non_heap_cl; 5268 } 5269 5270 // Keep alive closure. 5271 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5272 5273 // Complete GC closure 5274 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5275 5276 // Call the reference processing task's work routine. 5277 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5278 5279 // Note we cannot assert that the refs array is empty here as not all 5280 // of the processing tasks (specifically phase2 - pp2_work) execute 5281 // the complete_gc closure (which ordinarily would drain the queue) so 5282 // the queue may not be empty. 5283 } 5284 }; 5285 5286 // Driver routine for parallel reference processing. 5287 // Creates an instance of the ref processing gang 5288 // task and has the worker threads execute it. 5289 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5290 assert(_workers != NULL, "Need parallel worker threads."); 5291 5292 ParallelTaskTerminator terminator(_active_workers, _queues); 5293 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5294 5295 _workers->run_task(&proc_task_proxy); 5296 } 5297 5298 // Gang task for parallel reference enqueueing. 5299 5300 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5301 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5302 EnqueueTask& _enq_task; 5303 5304 public: 5305 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5306 AbstractGangTask("Enqueue reference objects in parallel"), 5307 _enq_task(enq_task) 5308 { } 5309 5310 virtual void work(uint worker_id) { 5311 _enq_task.work(worker_id); 5312 } 5313 }; 5314 5315 // Driver routine for parallel reference enqueueing. 5316 // Creates an instance of the ref enqueueing gang 5317 // task and has the worker threads execute it. 5318 5319 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5320 assert(_workers != NULL, "Need parallel worker threads."); 5321 5322 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5323 5324 _workers->run_task(&enq_task_proxy); 5325 } 5326 5327 // End of weak reference support closures 5328 5329 // Abstract task used to preserve (i.e. copy) any referent objects 5330 // that are in the collection set and are pointed to by reference 5331 // objects discovered by the CM ref processor. 5332 5333 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5334 protected: 5335 G1CollectedHeap* _g1h; 5336 RefToScanQueueSet *_queues; 5337 ParallelTaskTerminator _terminator; 5338 uint _n_workers; 5339 5340 public: 5341 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, uint workers, RefToScanQueueSet *task_queues) : 5342 AbstractGangTask("ParPreserveCMReferents"), 5343 _g1h(g1h), 5344 _queues(task_queues), 5345 _terminator(workers, _queues), 5346 _n_workers(workers) 5347 { } 5348 5349 void work(uint worker_id) { 5350 ResourceMark rm; 5351 HandleMark hm; 5352 5353 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5354 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5355 5356 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5357 5358 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5359 5360 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5361 5362 if (_g1h->collector_state()->during_initial_mark_pause()) { 5363 // We also need to mark copied objects. 5364 copy_non_heap_cl = ©_mark_non_heap_cl; 5365 } 5366 5367 // Is alive closure 5368 G1AlwaysAliveClosure always_alive(_g1h); 5369 5370 // Copying keep alive closure. Applied to referent objects that need 5371 // to be copied. 5372 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); 5373 5374 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5375 5376 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5377 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5378 5379 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5380 // So this must be true - but assert just in case someone decides to 5381 // change the worker ids. 5382 assert(worker_id < limit, "sanity"); 5383 assert(!rp->discovery_is_atomic(), "check this code"); 5384 5385 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5386 for (uint idx = worker_id; idx < limit; idx += stride) { 5387 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5388 5389 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5390 while (iter.has_next()) { 5391 // Since discovery is not atomic for the CM ref processor, we 5392 // can see some null referent objects. 5393 iter.load_ptrs(DEBUG_ONLY(true)); 5394 oop ref = iter.obj(); 5395 5396 // This will filter nulls. 5397 if (iter.is_referent_alive()) { 5398 iter.make_referent_alive(); 5399 } 5400 iter.move_to_next(); 5401 } 5402 } 5403 5404 // Drain the queue - which may cause stealing 5405 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5406 drain_queue.do_void(); 5407 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5408 assert(pss.queue_is_empty(), "should be"); 5409 } 5410 }; 5411 5412 // Weak Reference processing during an evacuation pause (part 1). 5413 void G1CollectedHeap::process_discovered_references() { 5414 double ref_proc_start = os::elapsedTime(); 5415 5416 ReferenceProcessor* rp = _ref_processor_stw; 5417 assert(rp->discovery_enabled(), "should have been enabled"); 5418 5419 // Any reference objects, in the collection set, that were 'discovered' 5420 // by the CM ref processor should have already been copied (either by 5421 // applying the external root copy closure to the discovered lists, or 5422 // by following an RSet entry). 5423 // 5424 // But some of the referents, that are in the collection set, that these 5425 // reference objects point to may not have been copied: the STW ref 5426 // processor would have seen that the reference object had already 5427 // been 'discovered' and would have skipped discovering the reference, 5428 // but would not have treated the reference object as a regular oop. 5429 // As a result the copy closure would not have been applied to the 5430 // referent object. 5431 // 5432 // We need to explicitly copy these referent objects - the references 5433 // will be processed at the end of remarking. 5434 // 5435 // We also need to do this copying before we process the reference 5436 // objects discovered by the STW ref processor in case one of these 5437 // referents points to another object which is also referenced by an 5438 // object discovered by the STW ref processor. 5439 5440 uint no_of_gc_workers = workers()->active_workers(); 5441 5442 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5443 no_of_gc_workers, 5444 _task_queues); 5445 5446 workers()->run_task(&keep_cm_referents); 5447 5448 // Closure to test whether a referent is alive. 5449 G1STWIsAliveClosure is_alive(this); 5450 5451 // Even when parallel reference processing is enabled, the processing 5452 // of JNI refs is serial and performed serially by the current thread 5453 // rather than by a worker. The following PSS will be used for processing 5454 // JNI refs. 5455 5456 // Use only a single queue for this PSS. 5457 G1ParScanThreadState pss(this, 0, NULL); 5458 assert(pss.queue_is_empty(), "pre-condition"); 5459 5460 // We do not embed a reference processor in the copying/scanning 5461 // closures while we're actually processing the discovered 5462 // reference objects. 5463 5464 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5465 5466 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5467 5468 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5469 5470 if (collector_state()->during_initial_mark_pause()) { 5471 // We also need to mark copied objects. 5472 copy_non_heap_cl = ©_mark_non_heap_cl; 5473 } 5474 5475 // Keep alive closure. 5476 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss); 5477 5478 // Serial Complete GC closure 5479 G1STWDrainQueueClosure drain_queue(this, &pss); 5480 5481 // Setup the soft refs policy... 5482 rp->setup_policy(false); 5483 5484 ReferenceProcessorStats stats; 5485 if (!rp->processing_is_mt()) { 5486 // Serial reference processing... 5487 stats = rp->process_discovered_references(&is_alive, 5488 &keep_alive, 5489 &drain_queue, 5490 NULL, 5491 _gc_timer_stw, 5492 _gc_tracer_stw->gc_id()); 5493 } else { 5494 // Parallel reference processing 5495 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5496 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5497 5498 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5499 stats = rp->process_discovered_references(&is_alive, 5500 &keep_alive, 5501 &drain_queue, 5502 &par_task_executor, 5503 _gc_timer_stw, 5504 _gc_tracer_stw->gc_id()); 5505 } 5506 5507 _gc_tracer_stw->report_gc_reference_stats(stats); 5508 5509 // We have completed copying any necessary live referent objects. 5510 assert(pss.queue_is_empty(), "both queue and overflow should be empty"); 5511 5512 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5513 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5514 } 5515 5516 // Weak Reference processing during an evacuation pause (part 2). 5517 void G1CollectedHeap::enqueue_discovered_references() { 5518 double ref_enq_start = os::elapsedTime(); 5519 5520 ReferenceProcessor* rp = _ref_processor_stw; 5521 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5522 5523 // Now enqueue any remaining on the discovered lists on to 5524 // the pending list. 5525 if (!rp->processing_is_mt()) { 5526 // Serial reference processing... 5527 rp->enqueue_discovered_references(); 5528 } else { 5529 // Parallel reference enqueueing 5530 5531 uint n_workers = workers()->active_workers(); 5532 5533 assert(rp->num_q() == n_workers, "sanity"); 5534 assert(n_workers <= rp->max_num_q(), "sanity"); 5535 5536 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, n_workers); 5537 rp->enqueue_discovered_references(&par_task_executor); 5538 } 5539 5540 rp->verify_no_references_recorded(); 5541 assert(!rp->discovery_enabled(), "should have been disabled"); 5542 5543 // FIXME 5544 // CM's reference processing also cleans up the string and symbol tables. 5545 // Should we do that here also? We could, but it is a serial operation 5546 // and could significantly increase the pause time. 5547 5548 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5549 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5550 } 5551 5552 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5553 _expand_heap_after_alloc_failure = true; 5554 _evacuation_failed = false; 5555 5556 // Should G1EvacuationFailureALot be in effect for this GC? 5557 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5558 5559 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5560 5561 // Disable the hot card cache. 5562 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5563 hot_card_cache->reset_hot_cache_claimed_index(); 5564 hot_card_cache->set_use_cache(false); 5565 5566 const uint n_workers = workers()->active_workers(); 5567 5568 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5569 double start_par_time_sec = os::elapsedTime(); 5570 double end_par_time_sec; 5571 5572 { 5573 G1RootProcessor root_processor(this, n_workers); 5574 G1ParTask g1_par_task(this, _task_queues, &root_processor, n_workers); 5575 // InitialMark needs claim bits to keep track of the marked-through CLDs. 5576 if (collector_state()->during_initial_mark_pause()) { 5577 ClassLoaderDataGraph::clear_claimed_marks(); 5578 } 5579 5580 // The individual threads will set their evac-failure closures. 5581 if (PrintTerminationStats) { 5582 G1ParScanThreadState::print_termination_stats_hdr(); 5583 } 5584 5585 workers()->run_task(&g1_par_task); 5586 end_par_time_sec = os::elapsedTime(); 5587 5588 // Closing the inner scope will execute the destructor 5589 // for the G1RootProcessor object. We record the current 5590 // elapsed time before closing the scope so that time 5591 // taken for the destructor is NOT included in the 5592 // reported parallel time. 5593 } 5594 5595 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 5596 5597 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5598 phase_times->record_par_time(par_time_ms); 5599 5600 double code_root_fixup_time_ms = 5601 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5602 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 5603 5604 // Process any discovered reference objects - we have 5605 // to do this _before_ we retire the GC alloc regions 5606 // as we may have to copy some 'reachable' referent 5607 // objects (and their reachable sub-graphs) that were 5608 // not copied during the pause. 5609 process_discovered_references(); 5610 5611 if (G1StringDedup::is_enabled()) { 5612 double fixup_start = os::elapsedTime(); 5613 5614 G1STWIsAliveClosure is_alive(this); 5615 G1KeepAliveClosure keep_alive(this); 5616 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times); 5617 5618 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 5619 phase_times->record_string_dedup_fixup_time(fixup_time_ms); 5620 } 5621 5622 _allocator->release_gc_alloc_regions(evacuation_info); 5623 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5624 5625 // Reset and re-enable the hot card cache. 5626 // Note the counts for the cards in the regions in the 5627 // collection set are reset when the collection set is freed. 5628 hot_card_cache->reset_hot_cache(); 5629 hot_card_cache->set_use_cache(true); 5630 5631 purge_code_root_memory(); 5632 5633 if (evacuation_failed()) { 5634 remove_self_forwarding_pointers(); 5635 5636 // Reset the G1EvacuationFailureALot counters and flags 5637 // Note: the values are reset only when an actual 5638 // evacuation failure occurs. 5639 NOT_PRODUCT(reset_evacuation_should_fail();) 5640 } 5641 5642 // Enqueue any remaining references remaining on the STW 5643 // reference processor's discovered lists. We need to do 5644 // this after the card table is cleaned (and verified) as 5645 // the act of enqueueing entries on to the pending list 5646 // will log these updates (and dirty their associated 5647 // cards). We need these updates logged to update any 5648 // RSets. 5649 enqueue_discovered_references(); 5650 5651 redirty_logged_cards(); 5652 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5653 } 5654 5655 void G1CollectedHeap::free_region(HeapRegion* hr, 5656 FreeRegionList* free_list, 5657 bool par, 5658 bool locked) { 5659 assert(!hr->is_free(), "the region should not be free"); 5660 assert(!hr->is_empty(), "the region should not be empty"); 5661 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 5662 assert(free_list != NULL, "pre-condition"); 5663 5664 if (G1VerifyBitmaps) { 5665 MemRegion mr(hr->bottom(), hr->end()); 5666 concurrent_mark()->clearRangePrevBitmap(mr); 5667 } 5668 5669 // Clear the card counts for this region. 5670 // Note: we only need to do this if the region is not young 5671 // (since we don't refine cards in young regions). 5672 if (!hr->is_young()) { 5673 _cg1r->hot_card_cache()->reset_card_counts(hr); 5674 } 5675 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5676 free_list->add_ordered(hr); 5677 } 5678 5679 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5680 FreeRegionList* free_list, 5681 bool par) { 5682 assert(hr->is_starts_humongous(), "this is only for starts humongous regions"); 5683 assert(free_list != NULL, "pre-condition"); 5684 5685 size_t hr_capacity = hr->capacity(); 5686 // We need to read this before we make the region non-humongous, 5687 // otherwise the information will be gone. 5688 uint last_index = hr->last_hc_index(); 5689 hr->clear_humongous(); 5690 free_region(hr, free_list, par); 5691 5692 uint i = hr->hrm_index() + 1; 5693 while (i < last_index) { 5694 HeapRegion* curr_hr = region_at(i); 5695 assert(curr_hr->is_continues_humongous(), "invariant"); 5696 curr_hr->clear_humongous(); 5697 free_region(curr_hr, free_list, par); 5698 i += 1; 5699 } 5700 } 5701 5702 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 5703 const HeapRegionSetCount& humongous_regions_removed) { 5704 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 5705 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5706 _old_set.bulk_remove(old_regions_removed); 5707 _humongous_set.bulk_remove(humongous_regions_removed); 5708 } 5709 5710 } 5711 5712 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 5713 assert(list != NULL, "list can't be null"); 5714 if (!list->is_empty()) { 5715 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5716 _hrm.insert_list_into_free_list(list); 5717 } 5718 } 5719 5720 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 5721 decrease_used(bytes); 5722 } 5723 5724 class G1ParCleanupCTTask : public AbstractGangTask { 5725 G1SATBCardTableModRefBS* _ct_bs; 5726 G1CollectedHeap* _g1h; 5727 HeapRegion* volatile _su_head; 5728 public: 5729 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 5730 G1CollectedHeap* g1h) : 5731 AbstractGangTask("G1 Par Cleanup CT Task"), 5732 _ct_bs(ct_bs), _g1h(g1h) { } 5733 5734 void work(uint worker_id) { 5735 HeapRegion* r; 5736 while (r = _g1h->pop_dirty_cards_region()) { 5737 clear_cards(r); 5738 } 5739 } 5740 5741 void clear_cards(HeapRegion* r) { 5742 // Cards of the survivors should have already been dirtied. 5743 if (!r->is_survivor()) { 5744 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5745 } 5746 } 5747 }; 5748 5749 #ifndef PRODUCT 5750 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5751 G1CollectedHeap* _g1h; 5752 G1SATBCardTableModRefBS* _ct_bs; 5753 public: 5754 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 5755 : _g1h(g1h), _ct_bs(ct_bs) { } 5756 virtual bool doHeapRegion(HeapRegion* r) { 5757 if (r->is_survivor()) { 5758 _g1h->verify_dirty_region(r); 5759 } else { 5760 _g1h->verify_not_dirty_region(r); 5761 } 5762 return false; 5763 } 5764 }; 5765 5766 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5767 // All of the region should be clean. 5768 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5769 MemRegion mr(hr->bottom(), hr->end()); 5770 ct_bs->verify_not_dirty_region(mr); 5771 } 5772 5773 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5774 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5775 // dirty allocated blocks as they allocate them. The thread that 5776 // retires each region and replaces it with a new one will do a 5777 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5778 // not dirty that area (one less thing to have to do while holding 5779 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5780 // is dirty. 5781 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5782 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5783 if (hr->is_young()) { 5784 ct_bs->verify_g1_young_region(mr); 5785 } else { 5786 ct_bs->verify_dirty_region(mr); 5787 } 5788 } 5789 5790 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5791 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5792 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5793 verify_dirty_region(hr); 5794 } 5795 } 5796 5797 void G1CollectedHeap::verify_dirty_young_regions() { 5798 verify_dirty_young_list(_young_list->first_region()); 5799 } 5800 5801 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 5802 HeapWord* tams, HeapWord* end) { 5803 guarantee(tams <= end, 5804 err_msg("tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end))); 5805 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); 5806 if (result < end) { 5807 gclog_or_tty->cr(); 5808 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT, 5809 bitmap_name, p2i(result)); 5810 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT, 5811 bitmap_name, p2i(tams), p2i(end)); 5812 return false; 5813 } 5814 return true; 5815 } 5816 5817 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { 5818 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); 5819 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); 5820 5821 HeapWord* bottom = hr->bottom(); 5822 HeapWord* ptams = hr->prev_top_at_mark_start(); 5823 HeapWord* ntams = hr->next_top_at_mark_start(); 5824 HeapWord* end = hr->end(); 5825 5826 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); 5827 5828 bool res_n = true; 5829 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window 5830 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap 5831 // if we happen to be in that state. 5832 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) { 5833 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); 5834 } 5835 if (!res_p || !res_n) { 5836 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT, 5837 HR_FORMAT_PARAMS(hr)); 5838 gclog_or_tty->print_cr("#### Caller: %s", caller); 5839 return false; 5840 } 5841 return true; 5842 } 5843 5844 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { 5845 if (!G1VerifyBitmaps) return; 5846 5847 guarantee(verify_bitmaps(caller, hr), "bitmap verification"); 5848 } 5849 5850 class G1VerifyBitmapClosure : public HeapRegionClosure { 5851 private: 5852 const char* _caller; 5853 G1CollectedHeap* _g1h; 5854 bool _failures; 5855 5856 public: 5857 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : 5858 _caller(caller), _g1h(g1h), _failures(false) { } 5859 5860 bool failures() { return _failures; } 5861 5862 virtual bool doHeapRegion(HeapRegion* hr) { 5863 if (hr->is_continues_humongous()) return false; 5864 5865 bool result = _g1h->verify_bitmaps(_caller, hr); 5866 if (!result) { 5867 _failures = true; 5868 } 5869 return false; 5870 } 5871 }; 5872 5873 void G1CollectedHeap::check_bitmaps(const char* caller) { 5874 if (!G1VerifyBitmaps) return; 5875 5876 G1VerifyBitmapClosure cl(caller, this); 5877 heap_region_iterate(&cl); 5878 guarantee(!cl.failures(), "bitmap verification"); 5879 } 5880 5881 class G1CheckCSetFastTableClosure : public HeapRegionClosure { 5882 private: 5883 bool _failures; 5884 public: 5885 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { } 5886 5887 virtual bool doHeapRegion(HeapRegion* hr) { 5888 uint i = hr->hrm_index(); 5889 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i); 5890 if (hr->is_humongous()) { 5891 if (hr->in_collection_set()) { 5892 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i); 5893 _failures = true; 5894 return true; 5895 } 5896 if (cset_state.is_in_cset()) { 5897 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i); 5898 _failures = true; 5899 return true; 5900 } 5901 if (hr->is_continues_humongous() && cset_state.is_humongous()) { 5902 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i); 5903 _failures = true; 5904 return true; 5905 } 5906 } else { 5907 if (cset_state.is_humongous()) { 5908 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i); 5909 _failures = true; 5910 return true; 5911 } 5912 if (hr->in_collection_set() != cset_state.is_in_cset()) { 5913 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u", 5914 hr->in_collection_set(), cset_state.value(), i); 5915 _failures = true; 5916 return true; 5917 } 5918 if (cset_state.is_in_cset()) { 5919 if (hr->is_young() != (cset_state.is_young())) { 5920 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u", 5921 hr->is_young(), cset_state.value(), i); 5922 _failures = true; 5923 return true; 5924 } 5925 if (hr->is_old() != (cset_state.is_old())) { 5926 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u", 5927 hr->is_old(), cset_state.value(), i); 5928 _failures = true; 5929 return true; 5930 } 5931 } 5932 } 5933 return false; 5934 } 5935 5936 bool failures() const { return _failures; } 5937 }; 5938 5939 bool G1CollectedHeap::check_cset_fast_test() { 5940 G1CheckCSetFastTableClosure cl; 5941 _hrm.iterate(&cl); 5942 return !cl.failures(); 5943 } 5944 #endif // PRODUCT 5945 5946 void G1CollectedHeap::cleanUpCardTable() { 5947 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 5948 double start = os::elapsedTime(); 5949 5950 { 5951 // Iterate over the dirty cards region list. 5952 G1ParCleanupCTTask cleanup_task(ct_bs, this); 5953 5954 workers()->run_task(&cleanup_task); 5955 #ifndef PRODUCT 5956 if (G1VerifyCTCleanup || VerifyAfterGC) { 5957 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 5958 heap_region_iterate(&cleanup_verifier); 5959 } 5960 #endif 5961 } 5962 5963 double elapsed = os::elapsedTime() - start; 5964 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 5965 } 5966 5967 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 5968 size_t pre_used = 0; 5969 FreeRegionList local_free_list("Local List for CSet Freeing"); 5970 5971 double young_time_ms = 0.0; 5972 double non_young_time_ms = 0.0; 5973 5974 // Since the collection set is a superset of the the young list, 5975 // all we need to do to clear the young list is clear its 5976 // head and length, and unlink any young regions in the code below 5977 _young_list->clear(); 5978 5979 G1CollectorPolicy* policy = g1_policy(); 5980 5981 double start_sec = os::elapsedTime(); 5982 bool non_young = true; 5983 5984 HeapRegion* cur = cs_head; 5985 int age_bound = -1; 5986 size_t rs_lengths = 0; 5987 5988 while (cur != NULL) { 5989 assert(!is_on_master_free_list(cur), "sanity"); 5990 if (non_young) { 5991 if (cur->is_young()) { 5992 double end_sec = os::elapsedTime(); 5993 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5994 non_young_time_ms += elapsed_ms; 5995 5996 start_sec = os::elapsedTime(); 5997 non_young = false; 5998 } 5999 } else { 6000 if (!cur->is_young()) { 6001 double end_sec = os::elapsedTime(); 6002 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6003 young_time_ms += elapsed_ms; 6004 6005 start_sec = os::elapsedTime(); 6006 non_young = true; 6007 } 6008 } 6009 6010 rs_lengths += cur->rem_set()->occupied_locked(); 6011 6012 HeapRegion* next = cur->next_in_collection_set(); 6013 assert(cur->in_collection_set(), "bad CS"); 6014 cur->set_next_in_collection_set(NULL); 6015 clear_in_cset(cur); 6016 6017 if (cur->is_young()) { 6018 int index = cur->young_index_in_cset(); 6019 assert(index != -1, "invariant"); 6020 assert((uint) index < policy->young_cset_region_length(), "invariant"); 6021 size_t words_survived = _surviving_young_words[index]; 6022 cur->record_surv_words_in_group(words_survived); 6023 6024 // At this point the we have 'popped' cur from the collection set 6025 // (linked via next_in_collection_set()) but it is still in the 6026 // young list (linked via next_young_region()). Clear the 6027 // _next_young_region field. 6028 cur->set_next_young_region(NULL); 6029 } else { 6030 int index = cur->young_index_in_cset(); 6031 assert(index == -1, "invariant"); 6032 } 6033 6034 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 6035 (!cur->is_young() && cur->young_index_in_cset() == -1), 6036 "invariant" ); 6037 6038 if (!cur->evacuation_failed()) { 6039 MemRegion used_mr = cur->used_region(); 6040 6041 // And the region is empty. 6042 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 6043 pre_used += cur->used(); 6044 free_region(cur, &local_free_list, false /* par */, true /* locked */); 6045 } else { 6046 cur->uninstall_surv_rate_group(); 6047 if (cur->is_young()) { 6048 cur->set_young_index_in_cset(-1); 6049 } 6050 cur->set_evacuation_failed(false); 6051 // The region is now considered to be old. 6052 cur->set_old(); 6053 _old_set.add(cur); 6054 evacuation_info.increment_collectionset_used_after(cur->used()); 6055 } 6056 cur = next; 6057 } 6058 6059 evacuation_info.set_regions_freed(local_free_list.length()); 6060 policy->record_max_rs_lengths(rs_lengths); 6061 policy->cset_regions_freed(); 6062 6063 double end_sec = os::elapsedTime(); 6064 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6065 6066 if (non_young) { 6067 non_young_time_ms += elapsed_ms; 6068 } else { 6069 young_time_ms += elapsed_ms; 6070 } 6071 6072 prepend_to_freelist(&local_free_list); 6073 decrement_summary_bytes(pre_used); 6074 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 6075 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 6076 } 6077 6078 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 6079 private: 6080 FreeRegionList* _free_region_list; 6081 HeapRegionSet* _proxy_set; 6082 HeapRegionSetCount _humongous_regions_removed; 6083 size_t _freed_bytes; 6084 public: 6085 6086 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 6087 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { 6088 } 6089 6090 virtual bool doHeapRegion(HeapRegion* r) { 6091 if (!r->is_starts_humongous()) { 6092 return false; 6093 } 6094 6095 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 6096 6097 oop obj = (oop)r->bottom(); 6098 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); 6099 6100 // The following checks whether the humongous object is live are sufficient. 6101 // The main additional check (in addition to having a reference from the roots 6102 // or the young gen) is whether the humongous object has a remembered set entry. 6103 // 6104 // A humongous object cannot be live if there is no remembered set for it 6105 // because: 6106 // - there can be no references from within humongous starts regions referencing 6107 // the object because we never allocate other objects into them. 6108 // (I.e. there are no intra-region references that may be missed by the 6109 // remembered set) 6110 // - as soon there is a remembered set entry to the humongous starts region 6111 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 6112 // until the end of a concurrent mark. 6113 // 6114 // It is not required to check whether the object has been found dead by marking 6115 // or not, in fact it would prevent reclamation within a concurrent cycle, as 6116 // all objects allocated during that time are considered live. 6117 // SATB marking is even more conservative than the remembered set. 6118 // So if at this point in the collection there is no remembered set entry, 6119 // nobody has a reference to it. 6120 // At the start of collection we flush all refinement logs, and remembered sets 6121 // are completely up-to-date wrt to references to the humongous object. 6122 // 6123 // Other implementation considerations: 6124 // - never consider object arrays at this time because they would pose 6125 // considerable effort for cleaning up the the remembered sets. This is 6126 // required because stale remembered sets might reference locations that 6127 // are currently allocated into. 6128 uint region_idx = r->hrm_index(); 6129 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 6130 !r->rem_set()->is_empty()) { 6131 6132 if (G1TraceEagerReclaimHumongousObjects) { 6133 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", 6134 region_idx, 6135 (size_t)obj->size() * HeapWordSize, 6136 p2i(r->bottom()), 6137 r->region_num(), 6138 r->rem_set()->occupied(), 6139 r->rem_set()->strong_code_roots_list_length(), 6140 next_bitmap->isMarked(r->bottom()), 6141 g1h->is_humongous_reclaim_candidate(region_idx), 6142 obj->is_typeArray() 6143 ); 6144 } 6145 6146 return false; 6147 } 6148 6149 guarantee(obj->is_typeArray(), 6150 err_msg("Only eagerly reclaiming type arrays is supported, but the object " 6151 PTR_FORMAT " is not.", 6152 p2i(r->bottom()))); 6153 6154 if (G1TraceEagerReclaimHumongousObjects) { 6155 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", 6156 region_idx, 6157 (size_t)obj->size() * HeapWordSize, 6158 p2i(r->bottom()), 6159 r->region_num(), 6160 r->rem_set()->occupied(), 6161 r->rem_set()->strong_code_roots_list_length(), 6162 next_bitmap->isMarked(r->bottom()), 6163 g1h->is_humongous_reclaim_candidate(region_idx), 6164 obj->is_typeArray() 6165 ); 6166 } 6167 // Need to clear mark bit of the humongous object if already set. 6168 if (next_bitmap->isMarked(r->bottom())) { 6169 next_bitmap->clear(r->bottom()); 6170 } 6171 _freed_bytes += r->used(); 6172 r->set_containing_set(NULL); 6173 _humongous_regions_removed.increment(1u, r->capacity()); 6174 g1h->free_humongous_region(r, _free_region_list, false); 6175 6176 return false; 6177 } 6178 6179 HeapRegionSetCount& humongous_free_count() { 6180 return _humongous_regions_removed; 6181 } 6182 6183 size_t bytes_freed() const { 6184 return _freed_bytes; 6185 } 6186 6187 size_t humongous_reclaimed() const { 6188 return _humongous_regions_removed.length(); 6189 } 6190 }; 6191 6192 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 6193 assert_at_safepoint(true); 6194 6195 if (!G1EagerReclaimHumongousObjects || 6196 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) { 6197 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 6198 return; 6199 } 6200 6201 double start_time = os::elapsedTime(); 6202 6203 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 6204 6205 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 6206 heap_region_iterate(&cl); 6207 6208 HeapRegionSetCount empty_set; 6209 remove_from_old_sets(empty_set, cl.humongous_free_count()); 6210 6211 G1HRPrinter* hrp = hr_printer(); 6212 if (hrp->is_active()) { 6213 FreeRegionListIterator iter(&local_cleanup_list); 6214 while (iter.more_available()) { 6215 HeapRegion* hr = iter.get_next(); 6216 hrp->cleanup(hr); 6217 } 6218 } 6219 6220 prepend_to_freelist(&local_cleanup_list); 6221 decrement_summary_bytes(cl.bytes_freed()); 6222 6223 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 6224 cl.humongous_reclaimed()); 6225 } 6226 6227 // This routine is similar to the above but does not record 6228 // any policy statistics or update free lists; we are abandoning 6229 // the current incremental collection set in preparation of a 6230 // full collection. After the full GC we will start to build up 6231 // the incremental collection set again. 6232 // This is only called when we're doing a full collection 6233 // and is immediately followed by the tearing down of the young list. 6234 6235 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6236 HeapRegion* cur = cs_head; 6237 6238 while (cur != NULL) { 6239 HeapRegion* next = cur->next_in_collection_set(); 6240 assert(cur->in_collection_set(), "bad CS"); 6241 cur->set_next_in_collection_set(NULL); 6242 clear_in_cset(cur); 6243 cur->set_young_index_in_cset(-1); 6244 cur = next; 6245 } 6246 } 6247 6248 void G1CollectedHeap::set_free_regions_coming() { 6249 if (G1ConcRegionFreeingVerbose) { 6250 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6251 "setting free regions coming"); 6252 } 6253 6254 assert(!free_regions_coming(), "pre-condition"); 6255 _free_regions_coming = true; 6256 } 6257 6258 void G1CollectedHeap::reset_free_regions_coming() { 6259 assert(free_regions_coming(), "pre-condition"); 6260 6261 { 6262 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6263 _free_regions_coming = false; 6264 SecondaryFreeList_lock->notify_all(); 6265 } 6266 6267 if (G1ConcRegionFreeingVerbose) { 6268 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6269 "reset free regions coming"); 6270 } 6271 } 6272 6273 void G1CollectedHeap::wait_while_free_regions_coming() { 6274 // Most of the time we won't have to wait, so let's do a quick test 6275 // first before we take the lock. 6276 if (!free_regions_coming()) { 6277 return; 6278 } 6279 6280 if (G1ConcRegionFreeingVerbose) { 6281 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6282 "waiting for free regions"); 6283 } 6284 6285 { 6286 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6287 while (free_regions_coming()) { 6288 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6289 } 6290 } 6291 6292 if (G1ConcRegionFreeingVerbose) { 6293 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6294 "done waiting for free regions"); 6295 } 6296 } 6297 6298 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6299 _young_list->push_region(hr); 6300 } 6301 6302 class NoYoungRegionsClosure: public HeapRegionClosure { 6303 private: 6304 bool _success; 6305 public: 6306 NoYoungRegionsClosure() : _success(true) { } 6307 bool doHeapRegion(HeapRegion* r) { 6308 if (r->is_young()) { 6309 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 6310 p2i(r->bottom()), p2i(r->end())); 6311 _success = false; 6312 } 6313 return false; 6314 } 6315 bool success() { return _success; } 6316 }; 6317 6318 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6319 bool ret = _young_list->check_list_empty(check_sample); 6320 6321 if (check_heap) { 6322 NoYoungRegionsClosure closure; 6323 heap_region_iterate(&closure); 6324 ret = ret && closure.success(); 6325 } 6326 6327 return ret; 6328 } 6329 6330 class TearDownRegionSetsClosure : public HeapRegionClosure { 6331 private: 6332 HeapRegionSet *_old_set; 6333 6334 public: 6335 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6336 6337 bool doHeapRegion(HeapRegion* r) { 6338 if (r->is_old()) { 6339 _old_set->remove(r); 6340 } else { 6341 // We ignore free regions, we'll empty the free list afterwards. 6342 // We ignore young regions, we'll empty the young list afterwards. 6343 // We ignore humongous regions, we're not tearing down the 6344 // humongous regions set. 6345 assert(r->is_free() || r->is_young() || r->is_humongous(), 6346 "it cannot be another type"); 6347 } 6348 return false; 6349 } 6350 6351 ~TearDownRegionSetsClosure() { 6352 assert(_old_set->is_empty(), "post-condition"); 6353 } 6354 }; 6355 6356 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6357 assert_at_safepoint(true /* should_be_vm_thread */); 6358 6359 if (!free_list_only) { 6360 TearDownRegionSetsClosure cl(&_old_set); 6361 heap_region_iterate(&cl); 6362 6363 // Note that emptying the _young_list is postponed and instead done as 6364 // the first step when rebuilding the regions sets again. The reason for 6365 // this is that during a full GC string deduplication needs to know if 6366 // a collected region was young or old when the full GC was initiated. 6367 } 6368 _hrm.remove_all_free_regions(); 6369 } 6370 6371 void G1CollectedHeap::increase_used(size_t bytes) { 6372 _summary_bytes_used += bytes; 6373 } 6374 6375 void G1CollectedHeap::decrease_used(size_t bytes) { 6376 assert(_summary_bytes_used >= bytes, 6377 err_msg("invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 6378 _summary_bytes_used, bytes)); 6379 _summary_bytes_used -= bytes; 6380 } 6381 6382 void G1CollectedHeap::set_used(size_t bytes) { 6383 _summary_bytes_used = bytes; 6384 } 6385 6386 class RebuildRegionSetsClosure : public HeapRegionClosure { 6387 private: 6388 bool _free_list_only; 6389 HeapRegionSet* _old_set; 6390 HeapRegionManager* _hrm; 6391 size_t _total_used; 6392 6393 public: 6394 RebuildRegionSetsClosure(bool free_list_only, 6395 HeapRegionSet* old_set, HeapRegionManager* hrm) : 6396 _free_list_only(free_list_only), 6397 _old_set(old_set), _hrm(hrm), _total_used(0) { 6398 assert(_hrm->num_free_regions() == 0, "pre-condition"); 6399 if (!free_list_only) { 6400 assert(_old_set->is_empty(), "pre-condition"); 6401 } 6402 } 6403 6404 bool doHeapRegion(HeapRegion* r) { 6405 if (r->is_continues_humongous()) { 6406 return false; 6407 } 6408 6409 if (r->is_empty()) { 6410 // Add free regions to the free list 6411 r->set_free(); 6412 r->set_allocation_context(AllocationContext::system()); 6413 _hrm->insert_into_free_list(r); 6414 } else if (!_free_list_only) { 6415 assert(!r->is_young(), "we should not come across young regions"); 6416 6417 if (r->is_humongous()) { 6418 // We ignore humongous regions. We left the humongous set unchanged. 6419 } else { 6420 // Objects that were compacted would have ended up on regions 6421 // that were previously old or free. Archive regions (which are 6422 // old) will not have been touched. 6423 assert(r->is_free() || r->is_old(), "invariant"); 6424 // We now consider them old, so register as such. Leave 6425 // archive regions set that way, however, while still adding 6426 // them to the old set. 6427 if (!r->is_archive()) { 6428 r->set_old(); 6429 } 6430 _old_set->add(r); 6431 } 6432 _total_used += r->used(); 6433 } 6434 6435 return false; 6436 } 6437 6438 size_t total_used() { 6439 return _total_used; 6440 } 6441 }; 6442 6443 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6444 assert_at_safepoint(true /* should_be_vm_thread */); 6445 6446 if (!free_list_only) { 6447 _young_list->empty_list(); 6448 } 6449 6450 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 6451 heap_region_iterate(&cl); 6452 6453 if (!free_list_only) { 6454 set_used(cl.total_used()); 6455 if (_archive_allocator != NULL) { 6456 _archive_allocator->clear_used(); 6457 } 6458 } 6459 assert(used_unlocked() == recalculate_used(), 6460 err_msg("inconsistent used_unlocked(), " 6461 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 6462 used_unlocked(), recalculate_used())); 6463 } 6464 6465 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6466 _refine_cte_cl->set_concurrent(concurrent); 6467 } 6468 6469 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6470 HeapRegion* hr = heap_region_containing(p); 6471 return hr->is_in(p); 6472 } 6473 6474 // Methods for the mutator alloc region 6475 6476 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6477 bool force) { 6478 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6479 assert(!force || g1_policy()->can_expand_young_list(), 6480 "if force is true we should be able to expand the young list"); 6481 bool young_list_full = g1_policy()->is_young_list_full(); 6482 if (force || !young_list_full) { 6483 HeapRegion* new_alloc_region = new_region(word_size, 6484 false /* is_old */, 6485 false /* do_expand */); 6486 if (new_alloc_region != NULL) { 6487 set_region_short_lived_locked(new_alloc_region); 6488 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6489 check_bitmaps("Mutator Region Allocation", new_alloc_region); 6490 return new_alloc_region; 6491 } 6492 } 6493 return NULL; 6494 } 6495 6496 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6497 size_t allocated_bytes) { 6498 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6499 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 6500 6501 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6502 increase_used(allocated_bytes); 6503 _hr_printer.retire(alloc_region); 6504 // We update the eden sizes here, when the region is retired, 6505 // instead of when it's allocated, since this is the point that its 6506 // used space has been recored in _summary_bytes_used. 6507 g1mm()->update_eden_size(); 6508 } 6509 6510 // Methods for the GC alloc regions 6511 6512 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6513 uint count, 6514 InCSetState dest) { 6515 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6516 6517 if (count < g1_policy()->max_regions(dest)) { 6518 const bool is_survivor = (dest.is_young()); 6519 HeapRegion* new_alloc_region = new_region(word_size, 6520 !is_survivor, 6521 true /* do_expand */); 6522 if (new_alloc_region != NULL) { 6523 // We really only need to do this for old regions given that we 6524 // should never scan survivors. But it doesn't hurt to do it 6525 // for survivors too. 6526 new_alloc_region->record_timestamp(); 6527 if (is_survivor) { 6528 new_alloc_region->set_survivor(); 6529 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6530 check_bitmaps("Survivor Region Allocation", new_alloc_region); 6531 } else { 6532 new_alloc_region->set_old(); 6533 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6534 check_bitmaps("Old Region Allocation", new_alloc_region); 6535 } 6536 bool during_im = collector_state()->during_initial_mark_pause(); 6537 new_alloc_region->note_start_of_copying(during_im); 6538 return new_alloc_region; 6539 } 6540 } 6541 return NULL; 6542 } 6543 6544 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6545 size_t allocated_bytes, 6546 InCSetState dest) { 6547 bool during_im = collector_state()->during_initial_mark_pause(); 6548 alloc_region->note_end_of_copying(during_im); 6549 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6550 if (dest.is_young()) { 6551 young_list()->add_survivor_region(alloc_region); 6552 } else { 6553 _old_set.add(alloc_region); 6554 } 6555 _hr_printer.retire(alloc_region); 6556 } 6557 6558 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 6559 bool expanded = false; 6560 uint index = _hrm.find_highest_free(&expanded); 6561 6562 if (index != G1_NO_HRM_INDEX) { 6563 if (expanded) { 6564 ergo_verbose1(ErgoHeapSizing, 6565 "attempt heap expansion", 6566 ergo_format_reason("requested address range outside heap bounds") 6567 ergo_format_byte("region size"), 6568 HeapRegion::GrainWords * HeapWordSize); 6569 } 6570 _hrm.allocate_free_regions_starting_at(index, 1); 6571 return region_at(index); 6572 } 6573 return NULL; 6574 } 6575 6576 // Heap region set verification 6577 6578 class VerifyRegionListsClosure : public HeapRegionClosure { 6579 private: 6580 HeapRegionSet* _old_set; 6581 HeapRegionSet* _humongous_set; 6582 HeapRegionManager* _hrm; 6583 6584 public: 6585 HeapRegionSetCount _old_count; 6586 HeapRegionSetCount _humongous_count; 6587 HeapRegionSetCount _free_count; 6588 6589 VerifyRegionListsClosure(HeapRegionSet* old_set, 6590 HeapRegionSet* humongous_set, 6591 HeapRegionManager* hrm) : 6592 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm), 6593 _old_count(), _humongous_count(), _free_count(){ } 6594 6595 bool doHeapRegion(HeapRegion* hr) { 6596 if (hr->is_continues_humongous()) { 6597 return false; 6598 } 6599 6600 if (hr->is_young()) { 6601 // TODO 6602 } else if (hr->is_starts_humongous()) { 6603 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index())); 6604 _humongous_count.increment(1u, hr->capacity()); 6605 } else if (hr->is_empty()) { 6606 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index())); 6607 _free_count.increment(1u, hr->capacity()); 6608 } else if (hr->is_old()) { 6609 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index())); 6610 _old_count.increment(1u, hr->capacity()); 6611 } else { 6612 // There are no other valid region types. Check for one invalid 6613 // one we can identify: pinned without old or humongous set. 6614 assert(!hr->is_pinned(), err_msg("Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index())); 6615 ShouldNotReachHere(); 6616 } 6617 return false; 6618 } 6619 6620 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) { 6621 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 6622 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6623 old_set->total_capacity_bytes(), _old_count.capacity())); 6624 6625 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 6626 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6627 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 6628 6629 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())); 6630 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6631 free_list->total_capacity_bytes(), _free_count.capacity())); 6632 } 6633 }; 6634 6635 void G1CollectedHeap::verify_region_sets() { 6636 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6637 6638 // First, check the explicit lists. 6639 _hrm.verify(); 6640 { 6641 // Given that a concurrent operation might be adding regions to 6642 // the secondary free list we have to take the lock before 6643 // verifying it. 6644 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6645 _secondary_free_list.verify_list(); 6646 } 6647 6648 // If a concurrent region freeing operation is in progress it will 6649 // be difficult to correctly attributed any free regions we come 6650 // across to the correct free list given that they might belong to 6651 // one of several (free_list, secondary_free_list, any local lists, 6652 // etc.). So, if that's the case we will skip the rest of the 6653 // verification operation. Alternatively, waiting for the concurrent 6654 // operation to complete will have a non-trivial effect on the GC's 6655 // operation (no concurrent operation will last longer than the 6656 // interval between two calls to verification) and it might hide 6657 // any issues that we would like to catch during testing. 6658 if (free_regions_coming()) { 6659 return; 6660 } 6661 6662 // Make sure we append the secondary_free_list on the free_list so 6663 // that all free regions we will come across can be safely 6664 // attributed to the free_list. 6665 append_secondary_free_list_if_not_empty_with_lock(); 6666 6667 // Finally, make sure that the region accounting in the lists is 6668 // consistent with what we see in the heap. 6669 6670 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm); 6671 heap_region_iterate(&cl); 6672 cl.verify_counts(&_old_set, &_humongous_set, &_hrm); 6673 } 6674 6675 // Optimized nmethod scanning 6676 6677 class RegisterNMethodOopClosure: public OopClosure { 6678 G1CollectedHeap* _g1h; 6679 nmethod* _nm; 6680 6681 template <class T> void do_oop_work(T* p) { 6682 T heap_oop = oopDesc::load_heap_oop(p); 6683 if (!oopDesc::is_null(heap_oop)) { 6684 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6685 HeapRegion* hr = _g1h->heap_region_containing(obj); 6686 assert(!hr->is_continues_humongous(), 6687 err_msg("trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 6688 " starting at " HR_FORMAT, 6689 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6690 6691 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 6692 hr->add_strong_code_root_locked(_nm); 6693 } 6694 } 6695 6696 public: 6697 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6698 _g1h(g1h), _nm(nm) {} 6699 6700 void do_oop(oop* p) { do_oop_work(p); } 6701 void do_oop(narrowOop* p) { do_oop_work(p); } 6702 }; 6703 6704 class UnregisterNMethodOopClosure: public OopClosure { 6705 G1CollectedHeap* _g1h; 6706 nmethod* _nm; 6707 6708 template <class T> void do_oop_work(T* p) { 6709 T heap_oop = oopDesc::load_heap_oop(p); 6710 if (!oopDesc::is_null(heap_oop)) { 6711 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6712 HeapRegion* hr = _g1h->heap_region_containing(obj); 6713 assert(!hr->is_continues_humongous(), 6714 err_msg("trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 6715 " starting at " HR_FORMAT, 6716 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6717 6718 hr->remove_strong_code_root(_nm); 6719 } 6720 } 6721 6722 public: 6723 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6724 _g1h(g1h), _nm(nm) {} 6725 6726 void do_oop(oop* p) { do_oop_work(p); } 6727 void do_oop(narrowOop* p) { do_oop_work(p); } 6728 }; 6729 6730 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6731 CollectedHeap::register_nmethod(nm); 6732 6733 guarantee(nm != NULL, "sanity"); 6734 RegisterNMethodOopClosure reg_cl(this, nm); 6735 nm->oops_do(®_cl); 6736 } 6737 6738 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6739 CollectedHeap::unregister_nmethod(nm); 6740 6741 guarantee(nm != NULL, "sanity"); 6742 UnregisterNMethodOopClosure reg_cl(this, nm); 6743 nm->oops_do(®_cl, true); 6744 } 6745 6746 void G1CollectedHeap::purge_code_root_memory() { 6747 double purge_start = os::elapsedTime(); 6748 G1CodeRootSet::purge(); 6749 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6750 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6751 } 6752 6753 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6754 G1CollectedHeap* _g1h; 6755 6756 public: 6757 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6758 _g1h(g1h) {} 6759 6760 void do_code_blob(CodeBlob* cb) { 6761 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6762 if (nm == NULL) { 6763 return; 6764 } 6765 6766 if (ScavengeRootsInCode) { 6767 _g1h->register_nmethod(nm); 6768 } 6769 } 6770 }; 6771 6772 void G1CollectedHeap::rebuild_strong_code_roots() { 6773 RebuildStrongCodeRootClosure blob_cl(this); 6774 CodeCache::blobs_do(&blob_cl); 6775 }