1 /* 2 * Copyright (c) 2001, 2011, 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 "code/icBuffer.hpp" 27 #include "gc_implementation/g1/bufferingOopClosure.hpp" 28 #include "gc_implementation/g1/concurrentG1Refine.hpp" 29 #include "gc_implementation/g1/concurrentG1RefineThread.hpp" 30 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 31 #include "gc_implementation/g1/g1AllocRegion.inline.hpp" 32 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 33 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 34 #include "gc_implementation/g1/g1MarkSweep.hpp" 35 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 36 #include "gc_implementation/g1/g1RemSet.inline.hpp" 37 #include "gc_implementation/g1/heapRegionRemSet.hpp" 38 #include "gc_implementation/g1/heapRegionSeq.inline.hpp" 39 #include "gc_implementation/g1/vm_operations_g1.hpp" 40 #include "gc_implementation/shared/isGCActiveMark.hpp" 41 #include "memory/gcLocker.inline.hpp" 42 #include "memory/genOopClosures.inline.hpp" 43 #include "memory/generationSpec.hpp" 44 #include "oops/oop.inline.hpp" 45 #include "oops/oop.pcgc.inline.hpp" 46 #include "runtime/aprofiler.hpp" 47 #include "runtime/vmThread.hpp" 48 49 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 50 51 // turn it on so that the contents of the young list (scan-only / 52 // to-be-collected) are printed at "strategic" points before / during 53 // / after the collection --- this is useful for debugging 54 #define YOUNG_LIST_VERBOSE 0 55 // CURRENT STATUS 56 // This file is under construction. Search for "FIXME". 57 58 // INVARIANTS/NOTES 59 // 60 // All allocation activity covered by the G1CollectedHeap interface is 61 // serialized by acquiring the HeapLock. This happens in mem_allocate 62 // and allocate_new_tlab, which are the "entry" points to the 63 // allocation code from the rest of the JVM. (Note that this does not 64 // apply to TLAB allocation, which is not part of this interface: it 65 // is done by clients of this interface.) 66 67 // Local to this file. 68 69 class RefineCardTableEntryClosure: public CardTableEntryClosure { 70 SuspendibleThreadSet* _sts; 71 G1RemSet* _g1rs; 72 ConcurrentG1Refine* _cg1r; 73 bool _concurrent; 74 public: 75 RefineCardTableEntryClosure(SuspendibleThreadSet* sts, 76 G1RemSet* g1rs, 77 ConcurrentG1Refine* cg1r) : 78 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true) 79 {} 80 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 81 bool oops_into_cset = _g1rs->concurrentRefineOneCard(card_ptr, worker_i, false); 82 // This path is executed by the concurrent refine or mutator threads, 83 // concurrently, and so we do not care if card_ptr contains references 84 // that point into the collection set. 85 assert(!oops_into_cset, "should be"); 86 87 if (_concurrent && _sts->should_yield()) { 88 // Caller will actually yield. 89 return false; 90 } 91 // Otherwise, we finished successfully; return true. 92 return true; 93 } 94 void set_concurrent(bool b) { _concurrent = b; } 95 }; 96 97 98 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure { 99 int _calls; 100 G1CollectedHeap* _g1h; 101 CardTableModRefBS* _ctbs; 102 int _histo[256]; 103 public: 104 ClearLoggedCardTableEntryClosure() : 105 _calls(0) 106 { 107 _g1h = G1CollectedHeap::heap(); 108 _ctbs = (CardTableModRefBS*)_g1h->barrier_set(); 109 for (int i = 0; i < 256; i++) _histo[i] = 0; 110 } 111 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 112 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) { 113 _calls++; 114 unsigned char* ujb = (unsigned char*)card_ptr; 115 int ind = (int)(*ujb); 116 _histo[ind]++; 117 *card_ptr = -1; 118 } 119 return true; 120 } 121 int calls() { return _calls; } 122 void print_histo() { 123 gclog_or_tty->print_cr("Card table value histogram:"); 124 for (int i = 0; i < 256; i++) { 125 if (_histo[i] != 0) { 126 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]); 127 } 128 } 129 } 130 }; 131 132 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure { 133 int _calls; 134 G1CollectedHeap* _g1h; 135 CardTableModRefBS* _ctbs; 136 public: 137 RedirtyLoggedCardTableEntryClosure() : 138 _calls(0) 139 { 140 _g1h = G1CollectedHeap::heap(); 141 _ctbs = (CardTableModRefBS*)_g1h->barrier_set(); 142 } 143 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 144 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) { 145 _calls++; 146 *card_ptr = 0; 147 } 148 return true; 149 } 150 int calls() { return _calls; } 151 }; 152 153 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure { 154 public: 155 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 156 *card_ptr = CardTableModRefBS::dirty_card_val(); 157 return true; 158 } 159 }; 160 161 YoungList::YoungList(G1CollectedHeap* g1h) 162 : _g1h(g1h), _head(NULL), 163 _length(0), 164 _last_sampled_rs_lengths(0), 165 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) 166 { 167 guarantee( check_list_empty(false), "just making sure..." ); 168 } 169 170 void YoungList::push_region(HeapRegion *hr) { 171 assert(!hr->is_young(), "should not already be young"); 172 assert(hr->get_next_young_region() == NULL, "cause it should!"); 173 174 hr->set_next_young_region(_head); 175 _head = hr; 176 177 hr->set_young(); 178 double yg_surv_rate = _g1h->g1_policy()->predict_yg_surv_rate((int)_length); 179 ++_length; 180 } 181 182 void YoungList::add_survivor_region(HeapRegion* hr) { 183 assert(hr->is_survivor(), "should be flagged as survivor region"); 184 assert(hr->get_next_young_region() == NULL, "cause it should!"); 185 186 hr->set_next_young_region(_survivor_head); 187 if (_survivor_head == NULL) { 188 _survivor_tail = hr; 189 } 190 _survivor_head = hr; 191 192 ++_survivor_length; 193 } 194 195 void YoungList::empty_list(HeapRegion* list) { 196 while (list != NULL) { 197 HeapRegion* next = list->get_next_young_region(); 198 list->set_next_young_region(NULL); 199 list->uninstall_surv_rate_group(); 200 list->set_not_young(); 201 list = next; 202 } 203 } 204 205 void YoungList::empty_list() { 206 assert(check_list_well_formed(), "young list should be well formed"); 207 208 empty_list(_head); 209 _head = NULL; 210 _length = 0; 211 212 empty_list(_survivor_head); 213 _survivor_head = NULL; 214 _survivor_tail = NULL; 215 _survivor_length = 0; 216 217 _last_sampled_rs_lengths = 0; 218 219 assert(check_list_empty(false), "just making sure..."); 220 } 221 222 bool YoungList::check_list_well_formed() { 223 bool ret = true; 224 225 size_t length = 0; 226 HeapRegion* curr = _head; 227 HeapRegion* last = NULL; 228 while (curr != NULL) { 229 if (!curr->is_young()) { 230 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " 231 "incorrectly tagged (y: %d, surv: %d)", 232 curr->bottom(), curr->end(), 233 curr->is_young(), curr->is_survivor()); 234 ret = false; 235 } 236 ++length; 237 last = curr; 238 curr = curr->get_next_young_region(); 239 } 240 ret = ret && (length == _length); 241 242 if (!ret) { 243 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 244 gclog_or_tty->print_cr("### list has %d entries, _length is %d", 245 length, _length); 246 } 247 248 return ret; 249 } 250 251 bool YoungList::check_list_empty(bool check_sample) { 252 bool ret = true; 253 254 if (_length != 0) { 255 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %d", 256 _length); 257 ret = false; 258 } 259 if (check_sample && _last_sampled_rs_lengths != 0) { 260 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 261 ret = false; 262 } 263 if (_head != NULL) { 264 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 265 ret = false; 266 } 267 if (!ret) { 268 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 269 } 270 271 return ret; 272 } 273 274 void 275 YoungList::rs_length_sampling_init() { 276 _sampled_rs_lengths = 0; 277 _curr = _head; 278 } 279 280 bool 281 YoungList::rs_length_sampling_more() { 282 return _curr != NULL; 283 } 284 285 void 286 YoungList::rs_length_sampling_next() { 287 assert( _curr != NULL, "invariant" ); 288 size_t rs_length = _curr->rem_set()->occupied(); 289 290 _sampled_rs_lengths += rs_length; 291 292 // The current region may not yet have been added to the 293 // incremental collection set (it gets added when it is 294 // retired as the current allocation region). 295 if (_curr->in_collection_set()) { 296 // Update the collection set policy information for this region 297 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 298 } 299 300 _curr = _curr->get_next_young_region(); 301 if (_curr == NULL) { 302 _last_sampled_rs_lengths = _sampled_rs_lengths; 303 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 304 } 305 } 306 307 void 308 YoungList::reset_auxilary_lists() { 309 guarantee( is_empty(), "young list should be empty" ); 310 assert(check_list_well_formed(), "young list should be well formed"); 311 312 // Add survivor regions to SurvRateGroup. 313 _g1h->g1_policy()->note_start_adding_survivor_regions(); 314 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 315 316 for (HeapRegion* curr = _survivor_head; 317 curr != NULL; 318 curr = curr->get_next_young_region()) { 319 _g1h->g1_policy()->set_region_survivors(curr); 320 321 // The region is a non-empty survivor so let's add it to 322 // the incremental collection set for the next evacuation 323 // pause. 324 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 325 } 326 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 327 328 _head = _survivor_head; 329 _length = _survivor_length; 330 if (_survivor_head != NULL) { 331 assert(_survivor_tail != NULL, "cause it shouldn't be"); 332 assert(_survivor_length > 0, "invariant"); 333 _survivor_tail->set_next_young_region(NULL); 334 } 335 336 // Don't clear the survivor list handles until the start of 337 // the next evacuation pause - we need it in order to re-tag 338 // the survivor regions from this evacuation pause as 'young' 339 // at the start of the next. 340 341 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 342 343 assert(check_list_well_formed(), "young list should be well formed"); 344 } 345 346 void YoungList::print() { 347 HeapRegion* lists[] = {_head, _survivor_head}; 348 const char* names[] = {"YOUNG", "SURVIVOR"}; 349 350 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) { 351 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 352 HeapRegion *curr = lists[list]; 353 if (curr == NULL) 354 gclog_or_tty->print_cr(" empty"); 355 while (curr != NULL) { 356 gclog_or_tty->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, " 357 "age: %4d, y: %d, surv: %d", 358 curr->bottom(), curr->end(), 359 curr->top(), 360 curr->prev_top_at_mark_start(), 361 curr->next_top_at_mark_start(), 362 curr->top_at_conc_mark_count(), 363 curr->age_in_surv_rate_group_cond(), 364 curr->is_young(), 365 curr->is_survivor()); 366 curr = curr->get_next_young_region(); 367 } 368 } 369 370 gclog_or_tty->print_cr(""); 371 } 372 373 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 374 { 375 // Claim the right to put the region on the dirty cards region list 376 // by installing a self pointer. 377 HeapRegion* next = hr->get_next_dirty_cards_region(); 378 if (next == NULL) { 379 HeapRegion* res = (HeapRegion*) 380 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 381 NULL); 382 if (res == NULL) { 383 HeapRegion* head; 384 do { 385 // Put the region to the dirty cards region list. 386 head = _dirty_cards_region_list; 387 next = (HeapRegion*) 388 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 389 if (next == head) { 390 assert(hr->get_next_dirty_cards_region() == hr, 391 "hr->get_next_dirty_cards_region() != hr"); 392 if (next == NULL) { 393 // The last region in the list points to itself. 394 hr->set_next_dirty_cards_region(hr); 395 } else { 396 hr->set_next_dirty_cards_region(next); 397 } 398 } 399 } while (next != head); 400 } 401 } 402 } 403 404 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 405 { 406 HeapRegion* head; 407 HeapRegion* hr; 408 do { 409 head = _dirty_cards_region_list; 410 if (head == NULL) { 411 return NULL; 412 } 413 HeapRegion* new_head = head->get_next_dirty_cards_region(); 414 if (head == new_head) { 415 // The last region. 416 new_head = NULL; 417 } 418 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 419 head); 420 } while (hr != head); 421 assert(hr != NULL, "invariant"); 422 hr->set_next_dirty_cards_region(NULL); 423 return hr; 424 } 425 426 void G1CollectedHeap::stop_conc_gc_threads() { 427 _cg1r->stop(); 428 _cmThread->stop(); 429 } 430 431 #ifdef ASSERT 432 // A region is added to the collection set as it is retired 433 // so an address p can point to a region which will be in the 434 // collection set but has not yet been retired. This method 435 // therefore is only accurate during a GC pause after all 436 // regions have been retired. It is used for debugging 437 // to check if an nmethod has references to objects that can 438 // be move during a partial collection. Though it can be 439 // inaccurate, it is sufficient for G1 because the conservative 440 // implementation of is_scavengable() for G1 will indicate that 441 // all nmethods must be scanned during a partial collection. 442 bool G1CollectedHeap::is_in_partial_collection(const void* p) { 443 HeapRegion* hr = heap_region_containing(p); 444 return hr != NULL && hr->in_collection_set(); 445 } 446 #endif 447 448 // Returns true if the reference points to an object that 449 // can move in an incremental collecction. 450 bool G1CollectedHeap::is_scavengable(const void* p) { 451 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 452 G1CollectorPolicy* g1p = g1h->g1_policy(); 453 HeapRegion* hr = heap_region_containing(p); 454 if (hr == NULL) { 455 // perm gen (or null) 456 return false; 457 } else { 458 return !hr->isHumongous(); 459 } 460 } 461 462 void G1CollectedHeap::check_ct_logs_at_safepoint() { 463 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 464 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set(); 465 466 // Count the dirty cards at the start. 467 CountNonCleanMemRegionClosure count1(this); 468 ct_bs->mod_card_iterate(&count1); 469 int orig_count = count1.n(); 470 471 // First clear the logged cards. 472 ClearLoggedCardTableEntryClosure clear; 473 dcqs.set_closure(&clear); 474 dcqs.apply_closure_to_all_completed_buffers(); 475 dcqs.iterate_closure_all_threads(false); 476 clear.print_histo(); 477 478 // Now ensure that there's no dirty cards. 479 CountNonCleanMemRegionClosure count2(this); 480 ct_bs->mod_card_iterate(&count2); 481 if (count2.n() != 0) { 482 gclog_or_tty->print_cr("Card table has %d entries; %d originally", 483 count2.n(), orig_count); 484 } 485 guarantee(count2.n() == 0, "Card table should be clean."); 486 487 RedirtyLoggedCardTableEntryClosure redirty; 488 JavaThread::dirty_card_queue_set().set_closure(&redirty); 489 dcqs.apply_closure_to_all_completed_buffers(); 490 dcqs.iterate_closure_all_threads(false); 491 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.", 492 clear.calls(), orig_count); 493 guarantee(redirty.calls() == clear.calls(), 494 "Or else mechanism is broken."); 495 496 CountNonCleanMemRegionClosure count3(this); 497 ct_bs->mod_card_iterate(&count3); 498 if (count3.n() != orig_count) { 499 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.", 500 orig_count, count3.n()); 501 guarantee(count3.n() >= orig_count, "Should have restored them all."); 502 } 503 504 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl); 505 } 506 507 // Private class members. 508 509 G1CollectedHeap* G1CollectedHeap::_g1h; 510 511 // Private methods. 512 513 HeapRegion* 514 G1CollectedHeap::new_region_try_secondary_free_list() { 515 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 516 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 517 if (!_secondary_free_list.is_empty()) { 518 if (G1ConcRegionFreeingVerbose) { 519 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 520 "secondary_free_list has "SIZE_FORMAT" entries", 521 _secondary_free_list.length()); 522 } 523 // It looks as if there are free regions available on the 524 // secondary_free_list. Let's move them to the free_list and try 525 // again to allocate from it. 526 append_secondary_free_list(); 527 528 assert(!_free_list.is_empty(), "if the secondary_free_list was not " 529 "empty we should have moved at least one entry to the free_list"); 530 HeapRegion* res = _free_list.remove_head(); 531 if (G1ConcRegionFreeingVerbose) { 532 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 533 "allocated "HR_FORMAT" from secondary_free_list", 534 HR_FORMAT_PARAMS(res)); 535 } 536 return res; 537 } 538 539 // Wait here until we get notifed either when (a) there are no 540 // more free regions coming or (b) some regions have been moved on 541 // the secondary_free_list. 542 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 543 } 544 545 if (G1ConcRegionFreeingVerbose) { 546 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 547 "could not allocate from secondary_free_list"); 548 } 549 return NULL; 550 } 551 552 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) { 553 assert(!isHumongous(word_size) || 554 word_size <= (size_t) HeapRegion::GrainWords, 555 "the only time we use this to allocate a humongous region is " 556 "when we are allocating a single humongous region"); 557 558 HeapRegion* res; 559 if (G1StressConcRegionFreeing) { 560 if (!_secondary_free_list.is_empty()) { 561 if (G1ConcRegionFreeingVerbose) { 562 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 563 "forced to look at the secondary_free_list"); 564 } 565 res = new_region_try_secondary_free_list(); 566 if (res != NULL) { 567 return res; 568 } 569 } 570 } 571 res = _free_list.remove_head_or_null(); 572 if (res == NULL) { 573 if (G1ConcRegionFreeingVerbose) { 574 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 575 "res == NULL, trying the secondary_free_list"); 576 } 577 res = new_region_try_secondary_free_list(); 578 } 579 if (res == NULL && do_expand) { 580 if (expand(word_size * HeapWordSize)) { 581 // Even though the heap was expanded, it might not have reached 582 // the desired size. So, we cannot assume that the allocation 583 // will succeed. 584 res = _free_list.remove_head_or_null(); 585 } 586 } 587 return res; 588 } 589 590 size_t G1CollectedHeap::humongous_obj_allocate_find_first(size_t num_regions, 591 size_t word_size) { 592 assert(isHumongous(word_size), "word_size should be humongous"); 593 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 594 595 size_t first = G1_NULL_HRS_INDEX; 596 if (num_regions == 1) { 597 // Only one region to allocate, no need to go through the slower 598 // path. The caller will attempt the expasion if this fails, so 599 // let's not try to expand here too. 600 HeapRegion* hr = new_region(word_size, false /* do_expand */); 601 if (hr != NULL) { 602 first = hr->hrs_index(); 603 } else { 604 first = G1_NULL_HRS_INDEX; 605 } 606 } else { 607 // We can't allocate humongous regions while cleanupComplete() is 608 // running, since some of the regions we find to be empty might not 609 // yet be added to the free list and it is not straightforward to 610 // know which list they are on so that we can remove them. Note 611 // that we only need to do this if we need to allocate more than 612 // one region to satisfy the current humongous allocation 613 // request. If we are only allocating one region we use the common 614 // region allocation code (see above). 615 wait_while_free_regions_coming(); 616 append_secondary_free_list_if_not_empty_with_lock(); 617 618 if (free_regions() >= num_regions) { 619 first = _hrs.find_contiguous(num_regions); 620 if (first != G1_NULL_HRS_INDEX) { 621 for (size_t i = first; i < first + num_regions; ++i) { 622 HeapRegion* hr = region_at(i); 623 assert(hr->is_empty(), "sanity"); 624 assert(is_on_master_free_list(hr), "sanity"); 625 hr->set_pending_removal(true); 626 } 627 _free_list.remove_all_pending(num_regions); 628 } 629 } 630 } 631 return first; 632 } 633 634 HeapWord* 635 G1CollectedHeap::humongous_obj_allocate_initialize_regions(size_t first, 636 size_t num_regions, 637 size_t word_size) { 638 assert(first != G1_NULL_HRS_INDEX, "pre-condition"); 639 assert(isHumongous(word_size), "word_size should be humongous"); 640 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 641 642 // Index of last region in the series + 1. 643 size_t last = first + num_regions; 644 645 // We need to initialize the region(s) we just discovered. This is 646 // a bit tricky given that it can happen concurrently with 647 // refinement threads refining cards on these regions and 648 // potentially wanting to refine the BOT as they are scanning 649 // those cards (this can happen shortly after a cleanup; see CR 650 // 6991377). So we have to set up the region(s) carefully and in 651 // a specific order. 652 653 // The word size sum of all the regions we will allocate. 654 size_t word_size_sum = num_regions * HeapRegion::GrainWords; 655 assert(word_size <= word_size_sum, "sanity"); 656 657 // This will be the "starts humongous" region. 658 HeapRegion* first_hr = region_at(first); 659 // The header of the new object will be placed at the bottom of 660 // the first region. 661 HeapWord* new_obj = first_hr->bottom(); 662 // This will be the new end of the first region in the series that 663 // should also match the end of the last region in the seriers. 664 HeapWord* new_end = new_obj + word_size_sum; 665 // This will be the new top of the first region that will reflect 666 // this allocation. 667 HeapWord* new_top = new_obj + word_size; 668 669 // First, we need to zero the header of the space that we will be 670 // allocating. When we update top further down, some refinement 671 // threads might try to scan the region. By zeroing the header we 672 // ensure that any thread that will try to scan the region will 673 // come across the zero klass word and bail out. 674 // 675 // NOTE: It would not have been correct to have used 676 // CollectedHeap::fill_with_object() and make the space look like 677 // an int array. The thread that is doing the allocation will 678 // later update the object header to a potentially different array 679 // type and, for a very short period of time, the klass and length 680 // fields will be inconsistent. This could cause a refinement 681 // thread to calculate the object size incorrectly. 682 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 683 684 // We will set up the first region as "starts humongous". This 685 // will also update the BOT covering all the regions to reflect 686 // that there is a single object that starts at the bottom of the 687 // first region. 688 first_hr->set_startsHumongous(new_top, new_end); 689 690 // Then, if there are any, we will set up the "continues 691 // humongous" regions. 692 HeapRegion* hr = NULL; 693 for (size_t i = first + 1; i < last; ++i) { 694 hr = region_at(i); 695 hr->set_continuesHumongous(first_hr); 696 } 697 // If we have "continues humongous" regions (hr != NULL), then the 698 // end of the last one should match new_end. 699 assert(hr == NULL || hr->end() == new_end, "sanity"); 700 701 // Up to this point no concurrent thread would have been able to 702 // do any scanning on any region in this series. All the top 703 // fields still point to bottom, so the intersection between 704 // [bottom,top] and [card_start,card_end] will be empty. Before we 705 // update the top fields, we'll do a storestore to make sure that 706 // no thread sees the update to top before the zeroing of the 707 // object header and the BOT initialization. 708 OrderAccess::storestore(); 709 710 // Now that the BOT and the object header have been initialized, 711 // we can update top of the "starts humongous" region. 712 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 713 "new_top should be in this region"); 714 first_hr->set_top(new_top); 715 if (_hr_printer.is_active()) { 716 HeapWord* bottom = first_hr->bottom(); 717 HeapWord* end = first_hr->orig_end(); 718 if ((first + 1) == last) { 719 // the series has a single humongous region 720 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 721 } else { 722 // the series has more than one humongous regions 723 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 724 } 725 } 726 727 // Now, we will update the top fields of the "continues humongous" 728 // regions. The reason we need to do this is that, otherwise, 729 // these regions would look empty and this will confuse parts of 730 // G1. For example, the code that looks for a consecutive number 731 // of empty regions will consider them empty and try to 732 // re-allocate them. We can extend is_empty() to also include 733 // !continuesHumongous(), but it is easier to just update the top 734 // fields here. The way we set top for all regions (i.e., top == 735 // end for all regions but the last one, top == new_top for the 736 // last one) is actually used when we will free up the humongous 737 // region in free_humongous_region(). 738 hr = NULL; 739 for (size_t i = first + 1; i < last; ++i) { 740 hr = region_at(i); 741 if ((i + 1) == last) { 742 // last continues humongous region 743 assert(hr->bottom() < new_top && new_top <= hr->end(), 744 "new_top should fall on this region"); 745 hr->set_top(new_top); 746 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 747 } else { 748 // not last one 749 assert(new_top > hr->end(), "new_top should be above this region"); 750 hr->set_top(hr->end()); 751 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 752 } 753 } 754 // If we have continues humongous regions (hr != NULL), then the 755 // end of the last one should match new_end and its top should 756 // match new_top. 757 assert(hr == NULL || 758 (hr->end() == new_end && hr->top() == new_top), "sanity"); 759 760 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 761 _summary_bytes_used += first_hr->used(); 762 _humongous_set.add(first_hr); 763 764 return new_obj; 765 } 766 767 // If could fit into free regions w/o expansion, try. 768 // Otherwise, if can expand, do so. 769 // Otherwise, if using ex regions might help, try with ex given back. 770 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 771 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 772 773 verify_region_sets_optional(); 774 775 size_t num_regions = 776 round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 777 size_t x_size = expansion_regions(); 778 size_t fs = _hrs.free_suffix(); 779 size_t first = humongous_obj_allocate_find_first(num_regions, word_size); 780 if (first == G1_NULL_HRS_INDEX) { 781 // The only thing we can do now is attempt expansion. 782 if (fs + x_size >= num_regions) { 783 // If the number of regions we're trying to allocate for this 784 // object is at most the number of regions in the free suffix, 785 // then the call to humongous_obj_allocate_find_first() above 786 // should have succeeded and we wouldn't be here. 787 // 788 // We should only be trying to expand when the free suffix is 789 // not sufficient for the object _and_ we have some expansion 790 // room available. 791 assert(num_regions > fs, "earlier allocation should have succeeded"); 792 793 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) { 794 // Even though the heap was expanded, it might not have 795 // reached the desired size. So, we cannot assume that the 796 // allocation will succeed. 797 first = humongous_obj_allocate_find_first(num_regions, word_size); 798 } 799 } 800 } 801 802 HeapWord* result = NULL; 803 if (first != G1_NULL_HRS_INDEX) { 804 result = 805 humongous_obj_allocate_initialize_regions(first, num_regions, word_size); 806 assert(result != NULL, "it should always return a valid result"); 807 } 808 809 verify_region_sets_optional(); 810 811 return result; 812 } 813 814 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 815 assert_heap_not_locked_and_not_at_safepoint(); 816 assert(!isHumongous(word_size), "we do not allow humongous TLABs"); 817 818 unsigned int dummy_gc_count_before; 819 return attempt_allocation(word_size, &dummy_gc_count_before); 820 } 821 822 HeapWord* 823 G1CollectedHeap::mem_allocate(size_t word_size, 824 bool* gc_overhead_limit_was_exceeded) { 825 assert_heap_not_locked_and_not_at_safepoint(); 826 827 // Loop until the allocation is satisified, or unsatisfied after GC. 828 for (int try_count = 1; /* we'll return */; try_count += 1) { 829 unsigned int gc_count_before; 830 831 HeapWord* result = NULL; 832 if (!isHumongous(word_size)) { 833 result = attempt_allocation(word_size, &gc_count_before); 834 } else { 835 result = attempt_allocation_humongous(word_size, &gc_count_before); 836 } 837 if (result != NULL) { 838 return result; 839 } 840 841 // Create the garbage collection operation... 842 VM_G1CollectForAllocation op(gc_count_before, word_size); 843 // ...and get the VM thread to execute it. 844 VMThread::execute(&op); 845 846 if (op.prologue_succeeded() && op.pause_succeeded()) { 847 // If the operation was successful we'll return the result even 848 // if it is NULL. If the allocation attempt failed immediately 849 // after a Full GC, it's unlikely we'll be able to allocate now. 850 HeapWord* result = op.result(); 851 if (result != NULL && !isHumongous(word_size)) { 852 // Allocations that take place on VM operations do not do any 853 // card dirtying and we have to do it here. We only have to do 854 // this for non-humongous allocations, though. 855 dirty_young_block(result, word_size); 856 } 857 return result; 858 } else { 859 assert(op.result() == NULL, 860 "the result should be NULL if the VM op did not succeed"); 861 } 862 863 // Give a warning if we seem to be looping forever. 864 if ((QueuedAllocationWarningCount > 0) && 865 (try_count % QueuedAllocationWarningCount == 0)) { 866 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 867 } 868 } 869 870 ShouldNotReachHere(); 871 return NULL; 872 } 873 874 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 875 unsigned int *gc_count_before_ret) { 876 // Make sure you read the note in attempt_allocation_humongous(). 877 878 assert_heap_not_locked_and_not_at_safepoint(); 879 assert(!isHumongous(word_size), "attempt_allocation_slow() should not " 880 "be called for humongous allocation requests"); 881 882 // We should only get here after the first-level allocation attempt 883 // (attempt_allocation()) failed to allocate. 884 885 // We will loop until a) we manage to successfully perform the 886 // allocation or b) we successfully schedule a collection which 887 // fails to perform the allocation. b) is the only case when we'll 888 // return NULL. 889 HeapWord* result = NULL; 890 for (int try_count = 1; /* we'll return */; try_count += 1) { 891 bool should_try_gc; 892 unsigned int gc_count_before; 893 894 { 895 MutexLockerEx x(Heap_lock); 896 897 result = _mutator_alloc_region.attempt_allocation_locked(word_size, 898 false /* bot_updates */); 899 if (result != NULL) { 900 return result; 901 } 902 903 // If we reach here, attempt_allocation_locked() above failed to 904 // allocate a new region. So the mutator alloc region should be NULL. 905 assert(_mutator_alloc_region.get() == NULL, "only way to get here"); 906 907 if (GC_locker::is_active_and_needs_gc()) { 908 if (g1_policy()->can_expand_young_list()) { 909 result = _mutator_alloc_region.attempt_allocation_force(word_size, 910 false /* bot_updates */); 911 if (result != NULL) { 912 return result; 913 } 914 } 915 should_try_gc = false; 916 } else { 917 // Read the GC count while still holding the Heap_lock. 918 gc_count_before = SharedHeap::heap()->total_collections(); 919 should_try_gc = true; 920 } 921 } 922 923 if (should_try_gc) { 924 bool succeeded; 925 result = do_collection_pause(word_size, gc_count_before, &succeeded); 926 if (result != NULL) { 927 assert(succeeded, "only way to get back a non-NULL result"); 928 return result; 929 } 930 931 if (succeeded) { 932 // If we get here we successfully scheduled a collection which 933 // failed to allocate. No point in trying to allocate 934 // further. We'll just return NULL. 935 MutexLockerEx x(Heap_lock); 936 *gc_count_before_ret = SharedHeap::heap()->total_collections(); 937 return NULL; 938 } 939 } else { 940 GC_locker::stall_until_clear(); 941 } 942 943 // We can reach here if we were unsuccessul in scheduling a 944 // collection (because another thread beat us to it) or if we were 945 // stalled due to the GC locker. In either can we should retry the 946 // allocation attempt in case another thread successfully 947 // performed a collection and reclaimed enough space. We do the 948 // first attempt (without holding the Heap_lock) here and the 949 // follow-on attempt will be at the start of the next loop 950 // iteration (after taking the Heap_lock). 951 result = _mutator_alloc_region.attempt_allocation(word_size, 952 false /* bot_updates */); 953 if (result != NULL ){ 954 return result; 955 } 956 957 // Give a warning if we seem to be looping forever. 958 if ((QueuedAllocationWarningCount > 0) && 959 (try_count % QueuedAllocationWarningCount == 0)) { 960 warning("G1CollectedHeap::attempt_allocation_slow() " 961 "retries %d times", try_count); 962 } 963 } 964 965 ShouldNotReachHere(); 966 return NULL; 967 } 968 969 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 970 unsigned int * gc_count_before_ret) { 971 // The structure of this method has a lot of similarities to 972 // attempt_allocation_slow(). The reason these two were not merged 973 // into a single one is that such a method would require several "if 974 // allocation is not humongous do this, otherwise do that" 975 // conditional paths which would obscure its flow. In fact, an early 976 // version of this code did use a unified method which was harder to 977 // follow and, as a result, it had subtle bugs that were hard to 978 // track down. So keeping these two methods separate allows each to 979 // be more readable. It will be good to keep these two in sync as 980 // much as possible. 981 982 assert_heap_not_locked_and_not_at_safepoint(); 983 assert(isHumongous(word_size), "attempt_allocation_humongous() " 984 "should only be called for humongous allocations"); 985 986 // We will loop until a) we manage to successfully perform the 987 // allocation or b) we successfully schedule a collection which 988 // fails to perform the allocation. b) is the only case when we'll 989 // return NULL. 990 HeapWord* result = NULL; 991 for (int try_count = 1; /* we'll return */; try_count += 1) { 992 bool should_try_gc; 993 unsigned int gc_count_before; 994 995 { 996 MutexLockerEx x(Heap_lock); 997 998 // Given that humongous objects are not allocated in young 999 // regions, we'll first try to do the allocation without doing a 1000 // collection hoping that there's enough space in the heap. 1001 result = humongous_obj_allocate(word_size); 1002 if (result != NULL) { 1003 return result; 1004 } 1005 1006 if (GC_locker::is_active_and_needs_gc()) { 1007 should_try_gc = false; 1008 } else { 1009 // Read the GC count while still holding the Heap_lock. 1010 gc_count_before = SharedHeap::heap()->total_collections(); 1011 should_try_gc = true; 1012 } 1013 } 1014 1015 if (should_try_gc) { 1016 // If we failed to allocate the humongous object, we should try to 1017 // do a collection pause (if we're allowed) in case it reclaims 1018 // enough space for the allocation to succeed after the pause. 1019 1020 bool succeeded; 1021 result = do_collection_pause(word_size, gc_count_before, &succeeded); 1022 if (result != NULL) { 1023 assert(succeeded, "only way to get back a non-NULL result"); 1024 return result; 1025 } 1026 1027 if (succeeded) { 1028 // If we get here we successfully scheduled a collection which 1029 // failed to allocate. No point in trying to allocate 1030 // further. We'll just return NULL. 1031 MutexLockerEx x(Heap_lock); 1032 *gc_count_before_ret = SharedHeap::heap()->total_collections(); 1033 return NULL; 1034 } 1035 } else { 1036 GC_locker::stall_until_clear(); 1037 } 1038 1039 // We can reach here if we were unsuccessul in scheduling a 1040 // collection (because another thread beat us to it) or if we were 1041 // stalled due to the GC locker. In either can we should retry the 1042 // allocation attempt in case another thread successfully 1043 // performed a collection and reclaimed enough space. Give a 1044 // warning if we seem to be looping forever. 1045 1046 if ((QueuedAllocationWarningCount > 0) && 1047 (try_count % QueuedAllocationWarningCount == 0)) { 1048 warning("G1CollectedHeap::attempt_allocation_humongous() " 1049 "retries %d times", try_count); 1050 } 1051 } 1052 1053 ShouldNotReachHere(); 1054 return NULL; 1055 } 1056 1057 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1058 bool expect_null_mutator_alloc_region) { 1059 assert_at_safepoint(true /* should_be_vm_thread */); 1060 assert(_mutator_alloc_region.get() == NULL || 1061 !expect_null_mutator_alloc_region, 1062 "the current alloc region was unexpectedly found to be non-NULL"); 1063 1064 if (!isHumongous(word_size)) { 1065 return _mutator_alloc_region.attempt_allocation_locked(word_size, 1066 false /* bot_updates */); 1067 } else { 1068 return humongous_obj_allocate(word_size); 1069 } 1070 1071 ShouldNotReachHere(); 1072 } 1073 1074 class PostMCRemSetClearClosure: public HeapRegionClosure { 1075 ModRefBarrierSet* _mr_bs; 1076 public: 1077 PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {} 1078 bool doHeapRegion(HeapRegion* r) { 1079 r->reset_gc_time_stamp(); 1080 if (r->continuesHumongous()) 1081 return false; 1082 HeapRegionRemSet* hrrs = r->rem_set(); 1083 if (hrrs != NULL) hrrs->clear(); 1084 // You might think here that we could clear just the cards 1085 // corresponding to the used region. But no: if we leave a dirty card 1086 // in a region we might allocate into, then it would prevent that card 1087 // from being enqueued, and cause it to be missed. 1088 // Re: the performance cost: we shouldn't be doing full GC anyway! 1089 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1090 return false; 1091 } 1092 }; 1093 1094 1095 class PostMCRemSetInvalidateClosure: public HeapRegionClosure { 1096 ModRefBarrierSet* _mr_bs; 1097 public: 1098 PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {} 1099 bool doHeapRegion(HeapRegion* r) { 1100 if (r->continuesHumongous()) return false; 1101 if (r->used_region().word_size() != 0) { 1102 _mr_bs->invalidate(r->used_region(), true /*whole heap*/); 1103 } 1104 return false; 1105 } 1106 }; 1107 1108 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1109 G1CollectedHeap* _g1h; 1110 UpdateRSOopClosure _cl; 1111 int _worker_i; 1112 public: 1113 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) : 1114 _cl(g1->g1_rem_set(), worker_i), 1115 _worker_i(worker_i), 1116 _g1h(g1) 1117 { } 1118 1119 bool doHeapRegion(HeapRegion* r) { 1120 if (!r->continuesHumongous()) { 1121 _cl.set_from(r); 1122 r->oop_iterate(&_cl); 1123 } 1124 return false; 1125 } 1126 }; 1127 1128 class ParRebuildRSTask: public AbstractGangTask { 1129 G1CollectedHeap* _g1; 1130 public: 1131 ParRebuildRSTask(G1CollectedHeap* g1) 1132 : AbstractGangTask("ParRebuildRSTask"), 1133 _g1(g1) 1134 { } 1135 1136 void work(int i) { 1137 RebuildRSOutOfRegionClosure rebuild_rs(_g1, i); 1138 _g1->heap_region_par_iterate_chunked(&rebuild_rs, i, 1139 HeapRegion::RebuildRSClaimValue); 1140 } 1141 }; 1142 1143 class PostCompactionPrinterClosure: public HeapRegionClosure { 1144 private: 1145 G1HRPrinter* _hr_printer; 1146 public: 1147 bool doHeapRegion(HeapRegion* hr) { 1148 assert(!hr->is_young(), "not expecting to find young regions"); 1149 // We only generate output for non-empty regions. 1150 if (!hr->is_empty()) { 1151 if (!hr->isHumongous()) { 1152 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1153 } else if (hr->startsHumongous()) { 1154 if (hr->capacity() == (size_t) HeapRegion::GrainBytes) { 1155 // single humongous region 1156 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1157 } else { 1158 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1159 } 1160 } else { 1161 assert(hr->continuesHumongous(), "only way to get here"); 1162 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1163 } 1164 } 1165 return false; 1166 } 1167 1168 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1169 : _hr_printer(hr_printer) { } 1170 }; 1171 1172 bool G1CollectedHeap::do_collection(bool explicit_gc, 1173 bool clear_all_soft_refs, 1174 size_t word_size) { 1175 assert_at_safepoint(true /* should_be_vm_thread */); 1176 1177 if (GC_locker::check_active_before_gc()) { 1178 return false; 1179 } 1180 1181 SvcGCMarker sgcm(SvcGCMarker::FULL); 1182 ResourceMark rm; 1183 1184 if (PrintHeapAtGC) { 1185 Universe::print_heap_before_gc(); 1186 } 1187 1188 verify_region_sets_optional(); 1189 1190 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1191 collector_policy()->should_clear_all_soft_refs(); 1192 1193 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1194 1195 { 1196 IsGCActiveMark x; 1197 1198 // Timing 1199 bool system_gc = (gc_cause() == GCCause::_java_lang_system_gc); 1200 assert(!system_gc || explicit_gc, "invariant"); 1201 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); 1202 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); 1203 TraceTime t(system_gc ? "Full GC (System.gc())" : "Full GC", 1204 PrintGC, true, gclog_or_tty); 1205 1206 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1207 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1208 1209 double start = os::elapsedTime(); 1210 g1_policy()->record_full_collection_start(); 1211 1212 wait_while_free_regions_coming(); 1213 append_secondary_free_list_if_not_empty_with_lock(); 1214 1215 gc_prologue(true); 1216 increment_total_collections(true /* full gc */); 1217 1218 size_t g1h_prev_used = used(); 1219 assert(used() == recalculate_used(), "Should be equal"); 1220 1221 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) { 1222 HandleMark hm; // Discard invalid handles created during verification 1223 gclog_or_tty->print(" VerifyBeforeGC:"); 1224 prepare_for_verify(); 1225 Universe::verify(/* allow dirty */ true, 1226 /* silent */ false, 1227 /* option */ VerifyOption_G1UsePrevMarking); 1228 1229 } 1230 pre_full_gc_dump(); 1231 1232 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1233 1234 // We want to discover references, but not process them yet. 1235 // This mode is disabled in 1236 // instanceRefKlass::process_discovered_references if the 1237 // generation does some collection work, or 1238 // instanceRefKlass::enqueue_discovered_references if the 1239 // generation returns without doing any work. 1240 ref_processor()->disable_discovery(); 1241 ref_processor()->abandon_partial_discovery(); 1242 ref_processor()->verify_no_references_recorded(); 1243 1244 // Abandon current iterations of concurrent marking and concurrent 1245 // refinement, if any are in progress. 1246 concurrent_mark()->abort(); 1247 1248 // Make sure we'll choose a new allocation region afterwards. 1249 release_mutator_alloc_region(); 1250 abandon_gc_alloc_regions(); 1251 g1_rem_set()->cleanupHRRS(); 1252 tear_down_region_lists(); 1253 1254 // We should call this after we retire any currently active alloc 1255 // regions so that all the ALLOC / RETIRE events are generated 1256 // before the start GC event. 1257 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1258 1259 // We may have added regions to the current incremental collection 1260 // set between the last GC or pause and now. We need to clear the 1261 // incremental collection set and then start rebuilding it afresh 1262 // after this full GC. 1263 abandon_collection_set(g1_policy()->inc_cset_head()); 1264 g1_policy()->clear_incremental_cset(); 1265 g1_policy()->stop_incremental_cset_building(); 1266 1267 empty_young_list(); 1268 g1_policy()->set_full_young_gcs(true); 1269 1270 // See the comment in G1CollectedHeap::ref_processing_init() about 1271 // how reference processing currently works in G1. 1272 1273 // Temporarily make reference _discovery_ single threaded (non-MT). 1274 ReferenceProcessorMTDiscoveryMutator rp_disc_ser(ref_processor(), false); 1275 1276 // Temporarily make refs discovery atomic 1277 ReferenceProcessorAtomicMutator rp_disc_atomic(ref_processor(), true); 1278 1279 // Temporarily clear _is_alive_non_header 1280 ReferenceProcessorIsAliveMutator rp_is_alive_null(ref_processor(), NULL); 1281 1282 ref_processor()->enable_discovery(); 1283 ref_processor()->setup_policy(do_clear_all_soft_refs); 1284 // Do collection work 1285 { 1286 HandleMark hm; // Discard invalid handles created during gc 1287 G1MarkSweep::invoke_at_safepoint(ref_processor(), do_clear_all_soft_refs); 1288 } 1289 assert(free_regions() == 0, "we should not have added any free regions"); 1290 rebuild_region_lists(); 1291 1292 _summary_bytes_used = recalculate_used(); 1293 1294 ref_processor()->enqueue_discovered_references(); 1295 1296 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1297 1298 MemoryService::track_memory_usage(); 1299 1300 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) { 1301 HandleMark hm; // Discard invalid handles created during verification 1302 gclog_or_tty->print(" VerifyAfterGC:"); 1303 prepare_for_verify(); 1304 Universe::verify(/* allow dirty */ false, 1305 /* silent */ false, 1306 /* option */ VerifyOption_G1UsePrevMarking); 1307 1308 } 1309 NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); 1310 1311 reset_gc_time_stamp(); 1312 // Since everything potentially moved, we will clear all remembered 1313 // sets, and clear all cards. Later we will rebuild remebered 1314 // sets. We will also reset the GC time stamps of the regions. 1315 PostMCRemSetClearClosure rs_clear(mr_bs()); 1316 heap_region_iterate(&rs_clear); 1317 1318 // Resize the heap if necessary. 1319 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1320 1321 if (_hr_printer.is_active()) { 1322 // We should do this after we potentially resize the heap so 1323 // that all the COMMIT / UNCOMMIT events are generated before 1324 // the end GC event. 1325 1326 PostCompactionPrinterClosure cl(hr_printer()); 1327 heap_region_iterate(&cl); 1328 1329 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1330 } 1331 1332 if (_cg1r->use_cache()) { 1333 _cg1r->clear_and_record_card_counts(); 1334 _cg1r->clear_hot_cache(); 1335 } 1336 1337 // Rebuild remembered sets of all regions. 1338 1339 if (G1CollectedHeap::use_parallel_gc_threads()) { 1340 ParRebuildRSTask rebuild_rs_task(this); 1341 assert(check_heap_region_claim_values( 1342 HeapRegion::InitialClaimValue), "sanity check"); 1343 set_par_threads(workers()->total_workers()); 1344 workers()->run_task(&rebuild_rs_task); 1345 set_par_threads(0); 1346 assert(check_heap_region_claim_values( 1347 HeapRegion::RebuildRSClaimValue), "sanity check"); 1348 reset_heap_region_claim_values(); 1349 } else { 1350 RebuildRSOutOfRegionClosure rebuild_rs(this); 1351 heap_region_iterate(&rebuild_rs); 1352 } 1353 1354 if (PrintGC) { 1355 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity()); 1356 } 1357 1358 if (true) { // FIXME 1359 // Ask the permanent generation to adjust size for full collections 1360 perm()->compute_new_size(); 1361 } 1362 1363 // Start a new incremental collection set for the next pause 1364 assert(g1_policy()->collection_set() == NULL, "must be"); 1365 g1_policy()->start_incremental_cset_building(); 1366 1367 // Clear the _cset_fast_test bitmap in anticipation of adding 1368 // regions to the incremental collection set for the next 1369 // evacuation pause. 1370 clear_cset_fast_test(); 1371 1372 init_mutator_alloc_region(); 1373 1374 double end = os::elapsedTime(); 1375 g1_policy()->record_full_collection_end(); 1376 1377 #ifdef TRACESPINNING 1378 ParallelTaskTerminator::print_termination_counts(); 1379 #endif 1380 1381 gc_epilogue(true); 1382 1383 // Discard all rset updates 1384 JavaThread::dirty_card_queue_set().abandon_logs(); 1385 assert(!G1DeferredRSUpdate 1386 || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any"); 1387 } 1388 1389 _young_list->reset_sampled_info(); 1390 // At this point there should be no regions in the 1391 // entire heap tagged as young. 1392 assert( check_young_list_empty(true /* check_heap */), 1393 "young list should be empty at this point"); 1394 1395 // Update the number of full collections that have been completed. 1396 increment_full_collections_completed(false /* concurrent */); 1397 1398 _hrs.verify_optional(); 1399 verify_region_sets_optional(); 1400 1401 if (PrintHeapAtGC) { 1402 Universe::print_heap_after_gc(); 1403 } 1404 g1mm()->update_counters(); 1405 post_full_gc_dump(); 1406 1407 return true; 1408 } 1409 1410 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1411 // do_collection() will return whether it succeeded in performing 1412 // the GC. Currently, there is no facility on the 1413 // do_full_collection() API to notify the caller than the collection 1414 // did not succeed (e.g., because it was locked out by the GC 1415 // locker). So, right now, we'll ignore the return value. 1416 bool dummy = do_collection(true, /* explicit_gc */ 1417 clear_all_soft_refs, 1418 0 /* word_size */); 1419 } 1420 1421 // This code is mostly copied from TenuredGeneration. 1422 void 1423 G1CollectedHeap:: 1424 resize_if_necessary_after_full_collection(size_t word_size) { 1425 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check"); 1426 1427 // Include the current allocation, if any, and bytes that will be 1428 // pre-allocated to support collections, as "used". 1429 const size_t used_after_gc = used(); 1430 const size_t capacity_after_gc = capacity(); 1431 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1432 1433 // This is enforced in arguments.cpp. 1434 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1435 "otherwise the code below doesn't make sense"); 1436 1437 // We don't have floating point command-line arguments 1438 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1439 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1440 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1441 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1442 1443 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1444 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1445 1446 // We have to be careful here as these two calculations can overflow 1447 // 32-bit size_t's. 1448 double used_after_gc_d = (double) used_after_gc; 1449 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1450 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1451 1452 // Let's make sure that they are both under the max heap size, which 1453 // by default will make them fit into a size_t. 1454 double desired_capacity_upper_bound = (double) max_heap_size; 1455 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1456 desired_capacity_upper_bound); 1457 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1458 desired_capacity_upper_bound); 1459 1460 // We can now safely turn them into size_t's. 1461 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1462 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1463 1464 // This assert only makes sense here, before we adjust them 1465 // with respect to the min and max heap size. 1466 assert(minimum_desired_capacity <= maximum_desired_capacity, 1467 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1468 "maximum_desired_capacity = "SIZE_FORMAT, 1469 minimum_desired_capacity, maximum_desired_capacity)); 1470 1471 // Should not be greater than the heap max size. No need to adjust 1472 // it with respect to the heap min size as it's a lower bound (i.e., 1473 // we'll try to make the capacity larger than it, not smaller). 1474 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1475 // Should not be less than the heap min size. No need to adjust it 1476 // with respect to the heap max size as it's an upper bound (i.e., 1477 // we'll try to make the capacity smaller than it, not greater). 1478 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1479 1480 if (PrintGC && Verbose) { 1481 const double free_percentage = 1482 (double) free_after_gc / (double) capacity_after_gc; 1483 gclog_or_tty->print_cr("Computing new size after full GC "); 1484 gclog_or_tty->print_cr(" " 1485 " minimum_free_percentage: %6.2f", 1486 minimum_free_percentage); 1487 gclog_or_tty->print_cr(" " 1488 " maximum_free_percentage: %6.2f", 1489 maximum_free_percentage); 1490 gclog_or_tty->print_cr(" " 1491 " capacity: %6.1fK" 1492 " minimum_desired_capacity: %6.1fK" 1493 " maximum_desired_capacity: %6.1fK", 1494 (double) capacity_after_gc / (double) K, 1495 (double) minimum_desired_capacity / (double) K, 1496 (double) maximum_desired_capacity / (double) K); 1497 gclog_or_tty->print_cr(" " 1498 " free_after_gc: %6.1fK" 1499 " used_after_gc: %6.1fK", 1500 (double) free_after_gc / (double) K, 1501 (double) used_after_gc / (double) K); 1502 gclog_or_tty->print_cr(" " 1503 " free_percentage: %6.2f", 1504 free_percentage); 1505 } 1506 if (capacity_after_gc < minimum_desired_capacity) { 1507 // Don't expand unless it's significant 1508 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1509 if (expand(expand_bytes)) { 1510 if (PrintGC && Verbose) { 1511 gclog_or_tty->print_cr(" " 1512 " expanding:" 1513 " max_heap_size: %6.1fK" 1514 " minimum_desired_capacity: %6.1fK" 1515 " expand_bytes: %6.1fK", 1516 (double) max_heap_size / (double) K, 1517 (double) minimum_desired_capacity / (double) K, 1518 (double) expand_bytes / (double) K); 1519 } 1520 } 1521 1522 // No expansion, now see if we want to shrink 1523 } else if (capacity_after_gc > maximum_desired_capacity) { 1524 // Capacity too large, compute shrinking size 1525 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1526 shrink(shrink_bytes); 1527 if (PrintGC && Verbose) { 1528 gclog_or_tty->print_cr(" " 1529 " shrinking:" 1530 " min_heap_size: %6.1fK" 1531 " maximum_desired_capacity: %6.1fK" 1532 " shrink_bytes: %6.1fK", 1533 (double) min_heap_size / (double) K, 1534 (double) maximum_desired_capacity / (double) K, 1535 (double) shrink_bytes / (double) K); 1536 } 1537 } 1538 } 1539 1540 1541 HeapWord* 1542 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1543 bool* succeeded) { 1544 assert_at_safepoint(true /* should_be_vm_thread */); 1545 1546 *succeeded = true; 1547 // Let's attempt the allocation first. 1548 HeapWord* result = 1549 attempt_allocation_at_safepoint(word_size, 1550 false /* expect_null_mutator_alloc_region */); 1551 if (result != NULL) { 1552 assert(*succeeded, "sanity"); 1553 return result; 1554 } 1555 1556 // In a G1 heap, we're supposed to keep allocation from failing by 1557 // incremental pauses. Therefore, at least for now, we'll favor 1558 // expansion over collection. (This might change in the future if we can 1559 // do something smarter than full collection to satisfy a failed alloc.) 1560 result = expand_and_allocate(word_size); 1561 if (result != NULL) { 1562 assert(*succeeded, "sanity"); 1563 return result; 1564 } 1565 1566 // Expansion didn't work, we'll try to do a Full GC. 1567 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1568 false, /* clear_all_soft_refs */ 1569 word_size); 1570 if (!gc_succeeded) { 1571 *succeeded = false; 1572 return NULL; 1573 } 1574 1575 // Retry the allocation 1576 result = attempt_allocation_at_safepoint(word_size, 1577 true /* expect_null_mutator_alloc_region */); 1578 if (result != NULL) { 1579 assert(*succeeded, "sanity"); 1580 return result; 1581 } 1582 1583 // Then, try a Full GC that will collect all soft references. 1584 gc_succeeded = do_collection(false, /* explicit_gc */ 1585 true, /* clear_all_soft_refs */ 1586 word_size); 1587 if (!gc_succeeded) { 1588 *succeeded = false; 1589 return NULL; 1590 } 1591 1592 // Retry the allocation once more 1593 result = attempt_allocation_at_safepoint(word_size, 1594 true /* expect_null_mutator_alloc_region */); 1595 if (result != NULL) { 1596 assert(*succeeded, "sanity"); 1597 return result; 1598 } 1599 1600 assert(!collector_policy()->should_clear_all_soft_refs(), 1601 "Flag should have been handled and cleared prior to this point"); 1602 1603 // What else? We might try synchronous finalization later. If the total 1604 // space available is large enough for the allocation, then a more 1605 // complete compaction phase than we've tried so far might be 1606 // appropriate. 1607 assert(*succeeded, "sanity"); 1608 return NULL; 1609 } 1610 1611 // Attempting to expand the heap sufficiently 1612 // to support an allocation of the given "word_size". If 1613 // successful, perform the allocation and return the address of the 1614 // allocated block, or else "NULL". 1615 1616 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1617 assert_at_safepoint(true /* should_be_vm_thread */); 1618 1619 verify_region_sets_optional(); 1620 1621 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1622 if (expand(expand_bytes)) { 1623 _hrs.verify_optional(); 1624 verify_region_sets_optional(); 1625 return attempt_allocation_at_safepoint(word_size, 1626 false /* expect_null_mutator_alloc_region */); 1627 } 1628 return NULL; 1629 } 1630 1631 void G1CollectedHeap::update_committed_space(HeapWord* old_end, 1632 HeapWord* new_end) { 1633 assert(old_end != new_end, "don't call this otherwise"); 1634 assert((HeapWord*) _g1_storage.high() == new_end, "invariant"); 1635 1636 // Update the committed mem region. 1637 _g1_committed.set_end(new_end); 1638 // Tell the card table about the update. 1639 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed); 1640 // Tell the BOT about the update. 1641 _bot_shared->resize(_g1_committed.word_size()); 1642 } 1643 1644 bool G1CollectedHeap::expand(size_t expand_bytes) { 1645 size_t old_mem_size = _g1_storage.committed_size(); 1646 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1647 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1648 HeapRegion::GrainBytes); 1649 1650 if (Verbose && PrintGC) { 1651 gclog_or_tty->print("Expanding garbage-first heap from %ldK by %ldK", 1652 old_mem_size/K, aligned_expand_bytes/K); 1653 } 1654 1655 // First commit the memory. 1656 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1657 bool successful = _g1_storage.expand_by(aligned_expand_bytes); 1658 if (successful) { 1659 // Then propagate this update to the necessary data structures. 1660 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1661 update_committed_space(old_end, new_end); 1662 1663 FreeRegionList expansion_list("Local Expansion List"); 1664 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list); 1665 assert(mr.start() == old_end, "post-condition"); 1666 // mr might be a smaller region than what was requested if 1667 // expand_by() was unable to allocate the HeapRegion instances 1668 assert(mr.end() <= new_end, "post-condition"); 1669 1670 size_t actual_expand_bytes = mr.byte_size(); 1671 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1672 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(), 1673 "post-condition"); 1674 if (actual_expand_bytes < aligned_expand_bytes) { 1675 // We could not expand _hrs to the desired size. In this case we 1676 // need to shrink the committed space accordingly. 1677 assert(mr.end() < new_end, "invariant"); 1678 1679 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes; 1680 // First uncommit the memory. 1681 _g1_storage.shrink_by(diff_bytes); 1682 // Then propagate this update to the necessary data structures. 1683 update_committed_space(new_end, mr.end()); 1684 } 1685 _free_list.add_as_tail(&expansion_list); 1686 1687 if (_hr_printer.is_active()) { 1688 HeapWord* curr = mr.start(); 1689 while (curr < mr.end()) { 1690 HeapWord* curr_end = curr + HeapRegion::GrainWords; 1691 _hr_printer.commit(curr, curr_end); 1692 curr = curr_end; 1693 } 1694 assert(curr == mr.end(), "post-condition"); 1695 } 1696 } else { 1697 // The expansion of the virtual storage space was unsuccessful. 1698 // Let's see if it was because we ran out of swap. 1699 if (G1ExitOnExpansionFailure && 1700 _g1_storage.uncommitted_size() >= aligned_expand_bytes) { 1701 // We had head room... 1702 vm_exit_out_of_memory(aligned_expand_bytes, "G1 heap expansion"); 1703 } 1704 } 1705 1706 if (Verbose && PrintGC) { 1707 size_t new_mem_size = _g1_storage.committed_size(); 1708 gclog_or_tty->print_cr("...%s, expanded to %ldK", 1709 (successful ? "Successful" : "Failed"), 1710 new_mem_size/K); 1711 } 1712 return successful; 1713 } 1714 1715 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1716 size_t old_mem_size = _g1_storage.committed_size(); 1717 size_t aligned_shrink_bytes = 1718 ReservedSpace::page_align_size_down(shrink_bytes); 1719 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1720 HeapRegion::GrainBytes); 1721 size_t num_regions_deleted = 0; 1722 MemRegion mr = _hrs.shrink_by(aligned_shrink_bytes, &num_regions_deleted); 1723 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1724 assert(mr.end() == old_end, "post-condition"); 1725 if (mr.byte_size() > 0) { 1726 if (_hr_printer.is_active()) { 1727 HeapWord* curr = mr.end(); 1728 while (curr > mr.start()) { 1729 HeapWord* curr_end = curr; 1730 curr -= HeapRegion::GrainWords; 1731 _hr_printer.uncommit(curr, curr_end); 1732 } 1733 assert(curr == mr.start(), "post-condition"); 1734 } 1735 1736 _g1_storage.shrink_by(mr.byte_size()); 1737 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1738 assert(mr.start() == new_end, "post-condition"); 1739 1740 _expansion_regions += num_regions_deleted; 1741 update_committed_space(old_end, new_end); 1742 HeapRegionRemSet::shrink_heap(n_regions()); 1743 1744 if (Verbose && PrintGC) { 1745 size_t new_mem_size = _g1_storage.committed_size(); 1746 gclog_or_tty->print_cr("Shrinking garbage-first heap from %ldK by %ldK to %ldK", 1747 old_mem_size/K, aligned_shrink_bytes/K, 1748 new_mem_size/K); 1749 } 1750 } 1751 } 1752 1753 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1754 verify_region_sets_optional(); 1755 1756 // We should only reach here at the end of a Full GC which means we 1757 // should not not be holding to any GC alloc regions. The method 1758 // below will make sure of that and do any remaining clean up. 1759 abandon_gc_alloc_regions(); 1760 1761 // Instead of tearing down / rebuilding the free lists here, we 1762 // could instead use the remove_all_pending() method on free_list to 1763 // remove only the ones that we need to remove. 1764 tear_down_region_lists(); // We will rebuild them in a moment. 1765 shrink_helper(shrink_bytes); 1766 rebuild_region_lists(); 1767 1768 _hrs.verify_optional(); 1769 verify_region_sets_optional(); 1770 } 1771 1772 // Public methods. 1773 1774 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1775 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1776 #endif // _MSC_VER 1777 1778 1779 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1780 SharedHeap(policy_), 1781 _g1_policy(policy_), 1782 _dirty_card_queue_set(false), 1783 _into_cset_dirty_card_queue_set(false), 1784 _is_alive_closure(this), 1785 _ref_processor(NULL), 1786 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)), 1787 _bot_shared(NULL), 1788 _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL), 1789 _evac_failure_scan_stack(NULL) , 1790 _mark_in_progress(false), 1791 _cg1r(NULL), _summary_bytes_used(0), 1792 _refine_cte_cl(NULL), 1793 _full_collection(false), 1794 _free_list("Master Free List"), 1795 _secondary_free_list("Secondary Free List"), 1796 _humongous_set("Master Humongous Set"), 1797 _free_regions_coming(false), 1798 _young_list(new YoungList(this)), 1799 _gc_time_stamp(0), 1800 _retained_old_gc_alloc_region(NULL), 1801 _surviving_young_words(NULL), 1802 _full_collections_completed(0), 1803 _in_cset_fast_test(NULL), 1804 _in_cset_fast_test_base(NULL), 1805 _dirty_cards_region_list(NULL) { 1806 _g1h = this; // To catch bugs. 1807 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) { 1808 vm_exit_during_initialization("Failed necessary allocation."); 1809 } 1810 1811 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1812 1813 int n_queues = MAX2((int)ParallelGCThreads, 1); 1814 _task_queues = new RefToScanQueueSet(n_queues); 1815 1816 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1817 assert(n_rem_sets > 0, "Invariant."); 1818 1819 HeapRegionRemSetIterator** iter_arr = 1820 NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues); 1821 for (int i = 0; i < n_queues; i++) { 1822 iter_arr[i] = new HeapRegionRemSetIterator(); 1823 } 1824 _rem_set_iterator = iter_arr; 1825 1826 for (int i = 0; i < n_queues; i++) { 1827 RefToScanQueue* q = new RefToScanQueue(); 1828 q->initialize(); 1829 _task_queues->register_queue(i, q); 1830 } 1831 1832 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1833 } 1834 1835 jint G1CollectedHeap::initialize() { 1836 CollectedHeap::pre_initialize(); 1837 os::enable_vtime(); 1838 1839 // Necessary to satisfy locking discipline assertions. 1840 1841 MutexLocker x(Heap_lock); 1842 1843 // We have to initialize the printer before committing the heap, as 1844 // it will be used then. 1845 _hr_printer.set_active(G1PrintHeapRegions); 1846 1847 // While there are no constraints in the GC code that HeapWordSize 1848 // be any particular value, there are multiple other areas in the 1849 // system which believe this to be true (e.g. oop->object_size in some 1850 // cases incorrectly returns the size in wordSize units rather than 1851 // HeapWordSize). 1852 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1853 1854 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1855 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1856 1857 // Ensure that the sizes are properly aligned. 1858 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1859 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1860 1861 _cg1r = new ConcurrentG1Refine(); 1862 1863 // Reserve the maximum. 1864 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation(); 1865 // Includes the perm-gen. 1866 1867 // When compressed oops are enabled, the preferred heap base 1868 // is calculated by subtracting the requested size from the 1869 // 32Gb boundary and using the result as the base address for 1870 // heap reservation. If the requested size is not aligned to 1871 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1872 // into the ReservedHeapSpace constructor) then the actual 1873 // base of the reserved heap may end up differing from the 1874 // address that was requested (i.e. the preferred heap base). 1875 // If this happens then we could end up using a non-optimal 1876 // compressed oops mode. 1877 1878 // Since max_byte_size is aligned to the size of a heap region (checked 1879 // above), we also need to align the perm gen size as it might not be. 1880 const size_t total_reserved = max_byte_size + 1881 align_size_up(pgs->max_size(), HeapRegion::GrainBytes); 1882 Universe::check_alignment(total_reserved, HeapRegion::GrainBytes, "g1 heap and perm"); 1883 1884 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop); 1885 1886 ReservedHeapSpace heap_rs(total_reserved, HeapRegion::GrainBytes, 1887 UseLargePages, addr); 1888 1889 if (UseCompressedOops) { 1890 if (addr != NULL && !heap_rs.is_reserved()) { 1891 // Failed to reserve at specified address - the requested memory 1892 // region is taken already, for example, by 'java' launcher. 1893 // Try again to reserver heap higher. 1894 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop); 1895 1896 ReservedHeapSpace heap_rs0(total_reserved, HeapRegion::GrainBytes, 1897 UseLargePages, addr); 1898 1899 if (addr != NULL && !heap_rs0.is_reserved()) { 1900 // Failed to reserve at specified address again - give up. 1901 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop); 1902 assert(addr == NULL, ""); 1903 1904 ReservedHeapSpace heap_rs1(total_reserved, HeapRegion::GrainBytes, 1905 UseLargePages, addr); 1906 heap_rs = heap_rs1; 1907 } else { 1908 heap_rs = heap_rs0; 1909 } 1910 } 1911 } 1912 1913 if (!heap_rs.is_reserved()) { 1914 vm_exit_during_initialization("Could not reserve enough space for object heap"); 1915 return JNI_ENOMEM; 1916 } 1917 1918 // It is important to do this in a way such that concurrent readers can't 1919 // temporarily think somethings in the heap. (I've actually seen this 1920 // happen in asserts: DLD.) 1921 _reserved.set_word_size(0); 1922 _reserved.set_start((HeapWord*)heap_rs.base()); 1923 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size())); 1924 1925 _expansion_regions = max_byte_size/HeapRegion::GrainBytes; 1926 1927 // Create the gen rem set (and barrier set) for the entire reserved region. 1928 _rem_set = collector_policy()->create_rem_set(_reserved, 2); 1929 set_barrier_set(rem_set()->bs()); 1930 if (barrier_set()->is_a(BarrierSet::ModRef)) { 1931 _mr_bs = (ModRefBarrierSet*)_barrier_set; 1932 } else { 1933 vm_exit_during_initialization("G1 requires a mod ref bs."); 1934 return JNI_ENOMEM; 1935 } 1936 1937 // Also create a G1 rem set. 1938 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) { 1939 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs()); 1940 } else { 1941 vm_exit_during_initialization("G1 requires a cardtable mod ref bs."); 1942 return JNI_ENOMEM; 1943 } 1944 1945 // Carve out the G1 part of the heap. 1946 1947 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1948 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(), 1949 g1_rs.size()/HeapWordSize); 1950 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size); 1951 1952 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set()); 1953 1954 _g1_storage.initialize(g1_rs, 0); 1955 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0); 1956 _hrs.initialize((HeapWord*) _g1_reserved.start(), 1957 (HeapWord*) _g1_reserved.end(), 1958 _expansion_regions); 1959 1960 // 6843694 - ensure that the maximum region index can fit 1961 // in the remembered set structures. 1962 const size_t max_region_idx = ((size_t)1 << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1963 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1964 1965 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1966 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1967 guarantee((size_t) HeapRegion::CardsPerRegion < max_cards_per_region, 1968 "too many cards per region"); 1969 1970 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1); 1971 1972 _bot_shared = new G1BlockOffsetSharedArray(_reserved, 1973 heap_word_size(init_byte_size)); 1974 1975 _g1h = this; 1976 1977 _in_cset_fast_test_length = max_regions(); 1978 _in_cset_fast_test_base = NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length); 1979 1980 // We're biasing _in_cset_fast_test to avoid subtracting the 1981 // beginning of the heap every time we want to index; basically 1982 // it's the same with what we do with the card table. 1983 _in_cset_fast_test = _in_cset_fast_test_base - 1984 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes); 1985 1986 // Clear the _cset_fast_test bitmap in anticipation of adding 1987 // regions to the incremental collection set for the first 1988 // evacuation pause. 1989 clear_cset_fast_test(); 1990 1991 // Create the ConcurrentMark data structure and thread. 1992 // (Must do this late, so that "max_regions" is defined.) 1993 _cm = new ConcurrentMark(heap_rs, (int) max_regions()); 1994 _cmThread = _cm->cmThread(); 1995 1996 // Initialize the from_card cache structure of HeapRegionRemSet. 1997 HeapRegionRemSet::init_heap(max_regions()); 1998 1999 // Now expand into the initial heap size. 2000 if (!expand(init_byte_size)) { 2001 vm_exit_during_initialization("Failed to allocate initial heap."); 2002 return JNI_ENOMEM; 2003 } 2004 2005 // Perform any initialization actions delegated to the policy. 2006 g1_policy()->init(); 2007 2008 g1_policy()->note_start_of_mark_thread(); 2009 2010 _refine_cte_cl = 2011 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(), 2012 g1_rem_set(), 2013 concurrent_g1_refine()); 2014 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl); 2015 2016 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2017 SATB_Q_FL_lock, 2018 G1SATBProcessCompletedThreshold, 2019 Shared_SATB_Q_lock); 2020 2021 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 2022 DirtyCardQ_FL_lock, 2023 concurrent_g1_refine()->yellow_zone(), 2024 concurrent_g1_refine()->red_zone(), 2025 Shared_DirtyCardQ_lock); 2026 2027 if (G1DeferredRSUpdate) { 2028 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 2029 DirtyCardQ_FL_lock, 2030 -1, // never trigger processing 2031 -1, // no limit on length 2032 Shared_DirtyCardQ_lock, 2033 &JavaThread::dirty_card_queue_set()); 2034 } 2035 2036 // Initialize the card queue set used to hold cards containing 2037 // references into the collection set. 2038 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon, 2039 DirtyCardQ_FL_lock, 2040 -1, // never trigger processing 2041 -1, // no limit on length 2042 Shared_DirtyCardQ_lock, 2043 &JavaThread::dirty_card_queue_set()); 2044 2045 // In case we're keeping closure specialization stats, initialize those 2046 // counts and that mechanism. 2047 SpecializationStats::clear(); 2048 2049 // Do later initialization work for concurrent refinement. 2050 _cg1r->init(); 2051 2052 // Here we allocate the dummy full region that is required by the 2053 // G1AllocRegion class. If we don't pass an address in the reserved 2054 // space here, lots of asserts fire. 2055 2056 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */, 2057 _g1_reserved.start()); 2058 // We'll re-use the same region whether the alloc region will 2059 // require BOT updates or not and, if it doesn't, then a non-young 2060 // region will complain that it cannot support allocations without 2061 // BOT updates. So we'll tag the dummy region as young to avoid that. 2062 dummy_region->set_young(); 2063 // Make sure it's full. 2064 dummy_region->set_top(dummy_region->end()); 2065 G1AllocRegion::setup(this, dummy_region); 2066 2067 init_mutator_alloc_region(); 2068 2069 // Do create of the monitoring and management support so that 2070 // values in the heap have been properly initialized. 2071 _g1mm = new G1MonitoringSupport(this, &_g1_storage); 2072 2073 return JNI_OK; 2074 } 2075 2076 void G1CollectedHeap::ref_processing_init() { 2077 // Reference processing in G1 currently works as follows: 2078 // 2079 // * There is only one reference processor instance that 2080 // 'spans' the entire heap. It is created by the code 2081 // below. 2082 // * Reference discovery is not enabled during an incremental 2083 // pause (see 6484982). 2084 // * Discoverered refs are not enqueued nor are they processed 2085 // during an incremental pause (see 6484982). 2086 // * Reference discovery is enabled at initial marking. 2087 // * Reference discovery is disabled and the discovered 2088 // references processed etc during remarking. 2089 // * Reference discovery is MT (see below). 2090 // * Reference discovery requires a barrier (see below). 2091 // * Reference processing is currently not MT (see 6608385). 2092 // * A full GC enables (non-MT) reference discovery and 2093 // processes any discovered references. 2094 2095 SharedHeap::ref_processing_init(); 2096 MemRegion mr = reserved_region(); 2097 _ref_processor = 2098 new ReferenceProcessor(mr, // span 2099 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing 2100 (int) ParallelGCThreads, // degree of mt processing 2101 ParallelGCThreads > 1 || ConcGCThreads > 1, // mt discovery 2102 (int) MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 2103 false, // Reference discovery is not atomic 2104 &_is_alive_closure, // is alive closure for efficiency 2105 true); // Setting next fields of discovered 2106 // lists requires a barrier. 2107 } 2108 2109 size_t G1CollectedHeap::capacity() const { 2110 return _g1_committed.byte_size(); 2111 } 2112 2113 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2114 DirtyCardQueue* into_cset_dcq, 2115 bool concurrent, 2116 int worker_i) { 2117 // Clean cards in the hot card cache 2118 concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq); 2119 2120 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2121 int n_completed_buffers = 0; 2122 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2123 n_completed_buffers++; 2124 } 2125 g1_policy()->record_update_rs_processed_buffers(worker_i, 2126 (double) n_completed_buffers); 2127 dcqs.clear_n_completed_buffers(); 2128 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2129 } 2130 2131 2132 // Computes the sum of the storage used by the various regions. 2133 2134 size_t G1CollectedHeap::used() const { 2135 assert(Heap_lock->owner() != NULL, 2136 "Should be owned on this thread's behalf."); 2137 size_t result = _summary_bytes_used; 2138 // Read only once in case it is set to NULL concurrently 2139 HeapRegion* hr = _mutator_alloc_region.get(); 2140 if (hr != NULL) 2141 result += hr->used(); 2142 return result; 2143 } 2144 2145 size_t G1CollectedHeap::used_unlocked() const { 2146 size_t result = _summary_bytes_used; 2147 return result; 2148 } 2149 2150 class SumUsedClosure: public HeapRegionClosure { 2151 size_t _used; 2152 public: 2153 SumUsedClosure() : _used(0) {} 2154 bool doHeapRegion(HeapRegion* r) { 2155 if (!r->continuesHumongous()) { 2156 _used += r->used(); 2157 } 2158 return false; 2159 } 2160 size_t result() { return _used; } 2161 }; 2162 2163 size_t G1CollectedHeap::recalculate_used() const { 2164 SumUsedClosure blk; 2165 heap_region_iterate(&blk); 2166 return blk.result(); 2167 } 2168 2169 size_t G1CollectedHeap::unsafe_max_alloc() { 2170 if (free_regions() > 0) return HeapRegion::GrainBytes; 2171 // otherwise, is there space in the current allocation region? 2172 2173 // We need to store the current allocation region in a local variable 2174 // here. The problem is that this method doesn't take any locks and 2175 // there may be other threads which overwrite the current allocation 2176 // region field. attempt_allocation(), for example, sets it to NULL 2177 // and this can happen *after* the NULL check here but before the call 2178 // to free(), resulting in a SIGSEGV. Note that this doesn't appear 2179 // to be a problem in the optimized build, since the two loads of the 2180 // current allocation region field are optimized away. 2181 HeapRegion* hr = _mutator_alloc_region.get(); 2182 if (hr == NULL) { 2183 return 0; 2184 } 2185 return hr->free(); 2186 } 2187 2188 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2189 return 2190 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) || 2191 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent)); 2192 } 2193 2194 #ifndef PRODUCT 2195 void G1CollectedHeap::allocate_dummy_regions() { 2196 // Let's fill up most of the region 2197 size_t word_size = HeapRegion::GrainWords - 1024; 2198 // And as a result the region we'll allocate will be humongous. 2199 guarantee(isHumongous(word_size), "sanity"); 2200 2201 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2202 // Let's use the existing mechanism for the allocation 2203 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2204 if (dummy_obj != NULL) { 2205 MemRegion mr(dummy_obj, word_size); 2206 CollectedHeap::fill_with_object(mr); 2207 } else { 2208 // If we can't allocate once, we probably cannot allocate 2209 // again. Let's get out of the loop. 2210 break; 2211 } 2212 } 2213 } 2214 #endif // !PRODUCT 2215 2216 void G1CollectedHeap::increment_full_collections_completed(bool concurrent) { 2217 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2218 2219 // We assume that if concurrent == true, then the caller is a 2220 // concurrent thread that was joined the Suspendible Thread 2221 // Set. If there's ever a cheap way to check this, we should add an 2222 // assert here. 2223 2224 // We have already incremented _total_full_collections at the start 2225 // of the GC, so total_full_collections() represents how many full 2226 // collections have been started. 2227 unsigned int full_collections_started = total_full_collections(); 2228 2229 // Given that this method is called at the end of a Full GC or of a 2230 // concurrent cycle, and those can be nested (i.e., a Full GC can 2231 // interrupt a concurrent cycle), the number of full collections 2232 // completed should be either one (in the case where there was no 2233 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2234 // behind the number of full collections started. 2235 2236 // This is the case for the inner caller, i.e. a Full GC. 2237 assert(concurrent || 2238 (full_collections_started == _full_collections_completed + 1) || 2239 (full_collections_started == _full_collections_completed + 2), 2240 err_msg("for inner caller (Full GC): full_collections_started = %u " 2241 "is inconsistent with _full_collections_completed = %u", 2242 full_collections_started, _full_collections_completed)); 2243 2244 // This is the case for the outer caller, i.e. the concurrent cycle. 2245 assert(!concurrent || 2246 (full_collections_started == _full_collections_completed + 1), 2247 err_msg("for outer caller (concurrent cycle): " 2248 "full_collections_started = %u " 2249 "is inconsistent with _full_collections_completed = %u", 2250 full_collections_started, _full_collections_completed)); 2251 2252 _full_collections_completed += 1; 2253 2254 // We need to clear the "in_progress" flag in the CM thread before 2255 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2256 // is set) so that if a waiter requests another System.gc() it doesn't 2257 // incorrectly see that a marking cyle is still in progress. 2258 if (concurrent) { 2259 _cmThread->clear_in_progress(); 2260 } 2261 2262 // This notify_all() will ensure that a thread that called 2263 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2264 // and it's waiting for a full GC to finish will be woken up. It is 2265 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2266 FullGCCount_lock->notify_all(); 2267 } 2268 2269 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) { 2270 assert_at_safepoint(true /* should_be_vm_thread */); 2271 GCCauseSetter gcs(this, cause); 2272 switch (cause) { 2273 case GCCause::_heap_inspection: 2274 case GCCause::_heap_dump: { 2275 HandleMark hm; 2276 do_full_collection(false); // don't clear all soft refs 2277 break; 2278 } 2279 default: // XXX FIX ME 2280 ShouldNotReachHere(); // Unexpected use of this function 2281 } 2282 } 2283 2284 void G1CollectedHeap::collect(GCCause::Cause cause) { 2285 // The caller doesn't have the Heap_lock 2286 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); 2287 2288 unsigned int gc_count_before; 2289 unsigned int full_gc_count_before; 2290 { 2291 MutexLocker ml(Heap_lock); 2292 2293 // Read the GC count while holding the Heap_lock 2294 gc_count_before = SharedHeap::heap()->total_collections(); 2295 full_gc_count_before = SharedHeap::heap()->total_full_collections(); 2296 } 2297 2298 if (should_do_concurrent_full_gc(cause)) { 2299 // Schedule an initial-mark evacuation pause that will start a 2300 // concurrent cycle. We're setting word_size to 0 which means that 2301 // we are not requesting a post-GC allocation. 2302 VM_G1IncCollectionPause op(gc_count_before, 2303 0, /* word_size */ 2304 true, /* should_initiate_conc_mark */ 2305 g1_policy()->max_pause_time_ms(), 2306 cause); 2307 VMThread::execute(&op); 2308 } else { 2309 if (cause == GCCause::_gc_locker 2310 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2311 2312 // Schedule a standard evacuation pause. We're setting word_size 2313 // to 0 which means that we are not requesting a post-GC allocation. 2314 VM_G1IncCollectionPause op(gc_count_before, 2315 0, /* word_size */ 2316 false, /* should_initiate_conc_mark */ 2317 g1_policy()->max_pause_time_ms(), 2318 cause); 2319 VMThread::execute(&op); 2320 } else { 2321 // Schedule a Full GC. 2322 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2323 VMThread::execute(&op); 2324 } 2325 } 2326 } 2327 2328 bool G1CollectedHeap::is_in(const void* p) const { 2329 HeapRegion* hr = _hrs.addr_to_region((HeapWord*) p); 2330 if (hr != NULL) { 2331 return hr->is_in(p); 2332 } else { 2333 return _perm_gen->as_gen()->is_in(p); 2334 } 2335 } 2336 2337 // Iteration functions. 2338 2339 // Iterates an OopClosure over all ref-containing fields of objects 2340 // within a HeapRegion. 2341 2342 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2343 MemRegion _mr; 2344 OopClosure* _cl; 2345 public: 2346 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl) 2347 : _mr(mr), _cl(cl) {} 2348 bool doHeapRegion(HeapRegion* r) { 2349 if (! r->continuesHumongous()) { 2350 r->oop_iterate(_cl); 2351 } 2352 return false; 2353 } 2354 }; 2355 2356 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) { 2357 IterateOopClosureRegionClosure blk(_g1_committed, cl); 2358 heap_region_iterate(&blk); 2359 if (do_perm) { 2360 perm_gen()->oop_iterate(cl); 2361 } 2362 } 2363 2364 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) { 2365 IterateOopClosureRegionClosure blk(mr, cl); 2366 heap_region_iterate(&blk); 2367 if (do_perm) { 2368 perm_gen()->oop_iterate(cl); 2369 } 2370 } 2371 2372 // Iterates an ObjectClosure over all objects within a HeapRegion. 2373 2374 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2375 ObjectClosure* _cl; 2376 public: 2377 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2378 bool doHeapRegion(HeapRegion* r) { 2379 if (! r->continuesHumongous()) { 2380 r->object_iterate(_cl); 2381 } 2382 return false; 2383 } 2384 }; 2385 2386 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) { 2387 IterateObjectClosureRegionClosure blk(cl); 2388 heap_region_iterate(&blk); 2389 if (do_perm) { 2390 perm_gen()->object_iterate(cl); 2391 } 2392 } 2393 2394 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) { 2395 // FIXME: is this right? 2396 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap"); 2397 } 2398 2399 // Calls a SpaceClosure on a HeapRegion. 2400 2401 class SpaceClosureRegionClosure: public HeapRegionClosure { 2402 SpaceClosure* _cl; 2403 public: 2404 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} 2405 bool doHeapRegion(HeapRegion* r) { 2406 _cl->do_space(r); 2407 return false; 2408 } 2409 }; 2410 2411 void G1CollectedHeap::space_iterate(SpaceClosure* cl) { 2412 SpaceClosureRegionClosure blk(cl); 2413 heap_region_iterate(&blk); 2414 } 2415 2416 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2417 _hrs.iterate(cl); 2418 } 2419 2420 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r, 2421 HeapRegionClosure* cl) const { 2422 _hrs.iterate_from(r, cl); 2423 } 2424 2425 void 2426 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl, 2427 int worker, 2428 jint claim_value) { 2429 const size_t regions = n_regions(); 2430 const size_t worker_num = (G1CollectedHeap::use_parallel_gc_threads() ? ParallelGCThreads : 1); 2431 // try to spread out the starting points of the workers 2432 const size_t start_index = regions / worker_num * (size_t) worker; 2433 2434 // each worker will actually look at all regions 2435 for (size_t count = 0; count < regions; ++count) { 2436 const size_t index = (start_index + count) % regions; 2437 assert(0 <= index && index < regions, "sanity"); 2438 HeapRegion* r = region_at(index); 2439 // we'll ignore "continues humongous" regions (we'll process them 2440 // when we come across their corresponding "start humongous" 2441 // region) and regions already claimed 2442 if (r->claim_value() == claim_value || r->continuesHumongous()) { 2443 continue; 2444 } 2445 // OK, try to claim it 2446 if (r->claimHeapRegion(claim_value)) { 2447 // success! 2448 assert(!r->continuesHumongous(), "sanity"); 2449 if (r->startsHumongous()) { 2450 // If the region is "starts humongous" we'll iterate over its 2451 // "continues humongous" first; in fact we'll do them 2452 // first. The order is important. In on case, calling the 2453 // closure on the "starts humongous" region might de-allocate 2454 // and clear all its "continues humongous" regions and, as a 2455 // result, we might end up processing them twice. So, we'll do 2456 // them first (notice: most closures will ignore them anyway) and 2457 // then we'll do the "starts humongous" region. 2458 for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) { 2459 HeapRegion* chr = region_at(ch_index); 2460 2461 // if the region has already been claimed or it's not 2462 // "continues humongous" we're done 2463 if (chr->claim_value() == claim_value || 2464 !chr->continuesHumongous()) { 2465 break; 2466 } 2467 2468 // Noone should have claimed it directly. We can given 2469 // that we claimed its "starts humongous" region. 2470 assert(chr->claim_value() != claim_value, "sanity"); 2471 assert(chr->humongous_start_region() == r, "sanity"); 2472 2473 if (chr->claimHeapRegion(claim_value)) { 2474 // we should always be able to claim it; noone else should 2475 // be trying to claim this region 2476 2477 bool res2 = cl->doHeapRegion(chr); 2478 assert(!res2, "Should not abort"); 2479 2480 // Right now, this holds (i.e., no closure that actually 2481 // does something with "continues humongous" regions 2482 // clears them). We might have to weaken it in the future, 2483 // but let's leave these two asserts here for extra safety. 2484 assert(chr->continuesHumongous(), "should still be the case"); 2485 assert(chr->humongous_start_region() == r, "sanity"); 2486 } else { 2487 guarantee(false, "we should not reach here"); 2488 } 2489 } 2490 } 2491 2492 assert(!r->continuesHumongous(), "sanity"); 2493 bool res = cl->doHeapRegion(r); 2494 assert(!res, "Should not abort"); 2495 } 2496 } 2497 } 2498 2499 class ResetClaimValuesClosure: public HeapRegionClosure { 2500 public: 2501 bool doHeapRegion(HeapRegion* r) { 2502 r->set_claim_value(HeapRegion::InitialClaimValue); 2503 return false; 2504 } 2505 }; 2506 2507 void 2508 G1CollectedHeap::reset_heap_region_claim_values() { 2509 ResetClaimValuesClosure blk; 2510 heap_region_iterate(&blk); 2511 } 2512 2513 #ifdef ASSERT 2514 // This checks whether all regions in the heap have the correct claim 2515 // value. I also piggy-backed on this a check to ensure that the 2516 // humongous_start_region() information on "continues humongous" 2517 // regions is correct. 2518 2519 class CheckClaimValuesClosure : public HeapRegionClosure { 2520 private: 2521 jint _claim_value; 2522 size_t _failures; 2523 HeapRegion* _sh_region; 2524 public: 2525 CheckClaimValuesClosure(jint claim_value) : 2526 _claim_value(claim_value), _failures(0), _sh_region(NULL) { } 2527 bool doHeapRegion(HeapRegion* r) { 2528 if (r->claim_value() != _claim_value) { 2529 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), " 2530 "claim value = %d, should be %d", 2531 r->bottom(), r->end(), r->claim_value(), 2532 _claim_value); 2533 ++_failures; 2534 } 2535 if (!r->isHumongous()) { 2536 _sh_region = NULL; 2537 } else if (r->startsHumongous()) { 2538 _sh_region = r; 2539 } else if (r->continuesHumongous()) { 2540 if (r->humongous_start_region() != _sh_region) { 2541 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), " 2542 "HS = "PTR_FORMAT", should be "PTR_FORMAT, 2543 r->bottom(), r->end(), 2544 r->humongous_start_region(), 2545 _sh_region); 2546 ++_failures; 2547 } 2548 } 2549 return false; 2550 } 2551 size_t failures() { 2552 return _failures; 2553 } 2554 }; 2555 2556 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) { 2557 CheckClaimValuesClosure cl(claim_value); 2558 heap_region_iterate(&cl); 2559 return cl.failures() == 0; 2560 } 2561 #endif // ASSERT 2562 2563 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2564 HeapRegion* r = g1_policy()->collection_set(); 2565 while (r != NULL) { 2566 HeapRegion* next = r->next_in_collection_set(); 2567 if (cl->doHeapRegion(r)) { 2568 cl->incomplete(); 2569 return; 2570 } 2571 r = next; 2572 } 2573 } 2574 2575 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2576 HeapRegionClosure *cl) { 2577 if (r == NULL) { 2578 // The CSet is empty so there's nothing to do. 2579 return; 2580 } 2581 2582 assert(r->in_collection_set(), 2583 "Start region must be a member of the collection set."); 2584 HeapRegion* cur = r; 2585 while (cur != NULL) { 2586 HeapRegion* next = cur->next_in_collection_set(); 2587 if (cl->doHeapRegion(cur) && false) { 2588 cl->incomplete(); 2589 return; 2590 } 2591 cur = next; 2592 } 2593 cur = g1_policy()->collection_set(); 2594 while (cur != r) { 2595 HeapRegion* next = cur->next_in_collection_set(); 2596 if (cl->doHeapRegion(cur) && false) { 2597 cl->incomplete(); 2598 return; 2599 } 2600 cur = next; 2601 } 2602 } 2603 2604 CompactibleSpace* G1CollectedHeap::first_compactible_space() { 2605 return n_regions() > 0 ? region_at(0) : NULL; 2606 } 2607 2608 2609 Space* G1CollectedHeap::space_containing(const void* addr) const { 2610 Space* res = heap_region_containing(addr); 2611 if (res == NULL) 2612 res = perm_gen()->space_containing(addr); 2613 return res; 2614 } 2615 2616 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2617 Space* sp = space_containing(addr); 2618 if (sp != NULL) { 2619 return sp->block_start(addr); 2620 } 2621 return NULL; 2622 } 2623 2624 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2625 Space* sp = space_containing(addr); 2626 assert(sp != NULL, "block_size of address outside of heap"); 2627 return sp->block_size(addr); 2628 } 2629 2630 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2631 Space* sp = space_containing(addr); 2632 return sp->block_is_obj(addr); 2633 } 2634 2635 bool G1CollectedHeap::supports_tlab_allocation() const { 2636 return true; 2637 } 2638 2639 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2640 return HeapRegion::GrainBytes; 2641 } 2642 2643 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2644 // Return the remaining space in the cur alloc region, but not less than 2645 // the min TLAB size. 2646 2647 // Also, this value can be at most the humongous object threshold, 2648 // since we can't allow tlabs to grow big enough to accomodate 2649 // humongous objects. 2650 2651 HeapRegion* hr = _mutator_alloc_region.get(); 2652 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize; 2653 if (hr == NULL) { 2654 return max_tlab_size; 2655 } else { 2656 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size); 2657 } 2658 } 2659 2660 size_t G1CollectedHeap::max_capacity() const { 2661 return _g1_reserved.byte_size(); 2662 } 2663 2664 jlong G1CollectedHeap::millis_since_last_gc() { 2665 // assert(false, "NYI"); 2666 return 0; 2667 } 2668 2669 void G1CollectedHeap::prepare_for_verify() { 2670 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2671 ensure_parsability(false); 2672 } 2673 g1_rem_set()->prepare_for_verify(); 2674 } 2675 2676 class VerifyLivenessOopClosure: public OopClosure { 2677 G1CollectedHeap* _g1h; 2678 VerifyOption _vo; 2679 public: 2680 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 2681 _g1h(g1h), _vo(vo) 2682 { } 2683 void do_oop(narrowOop *p) { do_oop_work(p); } 2684 void do_oop( oop *p) { do_oop_work(p); } 2685 2686 template <class T> void do_oop_work(T *p) { 2687 oop obj = oopDesc::load_decode_heap_oop(p); 2688 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 2689 "Dead object referenced by a not dead object"); 2690 } 2691 }; 2692 2693 class VerifyObjsInRegionClosure: public ObjectClosure { 2694 private: 2695 G1CollectedHeap* _g1h; 2696 size_t _live_bytes; 2697 HeapRegion *_hr; 2698 VerifyOption _vo; 2699 public: 2700 // _vo == UsePrevMarking -> use "prev" marking information, 2701 // _vo == UseNextMarking -> use "next" marking information, 2702 // _vo == UseMarkWord -> use mark word from object header. 2703 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 2704 : _live_bytes(0), _hr(hr), _vo(vo) { 2705 _g1h = G1CollectedHeap::heap(); 2706 } 2707 void do_object(oop o) { 2708 VerifyLivenessOopClosure isLive(_g1h, _vo); 2709 assert(o != NULL, "Huh?"); 2710 if (!_g1h->is_obj_dead_cond(o, _vo)) { 2711 // If the object is alive according to the mark word, 2712 // then verify that the marking information agrees. 2713 // Note we can't verify the contra-positive of the 2714 // above: if the object is dead (according to the mark 2715 // word), it may not be marked, or may have been marked 2716 // but has since became dead, or may have been allocated 2717 // since the last marking. 2718 if (_vo == VerifyOption_G1UseMarkWord) { 2719 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 2720 } 2721 2722 o->oop_iterate(&isLive); 2723 if (!_hr->obj_allocated_since_prev_marking(o)) { 2724 size_t obj_size = o->size(); // Make sure we don't overflow 2725 _live_bytes += (obj_size * HeapWordSize); 2726 } 2727 } 2728 } 2729 size_t live_bytes() { return _live_bytes; } 2730 }; 2731 2732 class PrintObjsInRegionClosure : public ObjectClosure { 2733 HeapRegion *_hr; 2734 G1CollectedHeap *_g1; 2735 public: 2736 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 2737 _g1 = G1CollectedHeap::heap(); 2738 }; 2739 2740 void do_object(oop o) { 2741 if (o != NULL) { 2742 HeapWord *start = (HeapWord *) o; 2743 size_t word_sz = o->size(); 2744 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 2745 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 2746 (void*) o, word_sz, 2747 _g1->isMarkedPrev(o), 2748 _g1->isMarkedNext(o), 2749 _hr->obj_allocated_since_prev_marking(o)); 2750 HeapWord *end = start + word_sz; 2751 HeapWord *cur; 2752 int *val; 2753 for (cur = start; cur < end; cur++) { 2754 val = (int *) cur; 2755 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val); 2756 } 2757 } 2758 } 2759 }; 2760 2761 class VerifyRegionClosure: public HeapRegionClosure { 2762 private: 2763 bool _allow_dirty; 2764 bool _par; 2765 VerifyOption _vo; 2766 bool _failures; 2767 public: 2768 // _vo == UsePrevMarking -> use "prev" marking information, 2769 // _vo == UseNextMarking -> use "next" marking information, 2770 // _vo == UseMarkWord -> use mark word from object header. 2771 VerifyRegionClosure(bool allow_dirty, bool par, VerifyOption vo) 2772 : _allow_dirty(allow_dirty), 2773 _par(par), 2774 _vo(vo), 2775 _failures(false) {} 2776 2777 bool failures() { 2778 return _failures; 2779 } 2780 2781 bool doHeapRegion(HeapRegion* r) { 2782 guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue, 2783 "Should be unclaimed at verify points."); 2784 if (!r->continuesHumongous()) { 2785 bool failures = false; 2786 r->verify(_allow_dirty, _vo, &failures); 2787 if (failures) { 2788 _failures = true; 2789 } else { 2790 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 2791 r->object_iterate(¬_dead_yet_cl); 2792 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 2793 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 2794 "max_live_bytes "SIZE_FORMAT" " 2795 "< calculated "SIZE_FORMAT, 2796 r->bottom(), r->end(), 2797 r->max_live_bytes(), 2798 not_dead_yet_cl.live_bytes()); 2799 _failures = true; 2800 } 2801 } 2802 } 2803 return false; // stop the region iteration if we hit a failure 2804 } 2805 }; 2806 2807 class VerifyRootsClosure: public OopsInGenClosure { 2808 private: 2809 G1CollectedHeap* _g1h; 2810 VerifyOption _vo; 2811 bool _failures; 2812 public: 2813 // _vo == UsePrevMarking -> use "prev" marking information, 2814 // _vo == UseNextMarking -> use "next" marking information, 2815 // _vo == UseMarkWord -> use mark word from object header. 2816 VerifyRootsClosure(VerifyOption vo) : 2817 _g1h(G1CollectedHeap::heap()), 2818 _vo(vo), 2819 _failures(false) { } 2820 2821 bool failures() { return _failures; } 2822 2823 template <class T> void do_oop_nv(T* p) { 2824 T heap_oop = oopDesc::load_heap_oop(p); 2825 if (!oopDesc::is_null(heap_oop)) { 2826 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 2827 if (_g1h->is_obj_dead_cond(obj, _vo)) { 2828 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 2829 "points to dead obj "PTR_FORMAT, p, (void*) obj); 2830 if (_vo == VerifyOption_G1UseMarkWord) { 2831 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 2832 } 2833 obj->print_on(gclog_or_tty); 2834 _failures = true; 2835 } 2836 } 2837 } 2838 2839 void do_oop(oop* p) { do_oop_nv(p); } 2840 void do_oop(narrowOop* p) { do_oop_nv(p); } 2841 }; 2842 2843 // This is the task used for parallel heap verification. 2844 2845 class G1ParVerifyTask: public AbstractGangTask { 2846 private: 2847 G1CollectedHeap* _g1h; 2848 bool _allow_dirty; 2849 VerifyOption _vo; 2850 bool _failures; 2851 2852 public: 2853 // _vo == UsePrevMarking -> use "prev" marking information, 2854 // _vo == UseNextMarking -> use "next" marking information, 2855 // _vo == UseMarkWord -> use mark word from object header. 2856 G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty, VerifyOption vo) : 2857 AbstractGangTask("Parallel verify task"), 2858 _g1h(g1h), 2859 _allow_dirty(allow_dirty), 2860 _vo(vo), 2861 _failures(false) { } 2862 2863 bool failures() { 2864 return _failures; 2865 } 2866 2867 void work(int worker_i) { 2868 HandleMark hm; 2869 VerifyRegionClosure blk(_allow_dirty, true, _vo); 2870 _g1h->heap_region_par_iterate_chunked(&blk, worker_i, 2871 HeapRegion::ParVerifyClaimValue); 2872 if (blk.failures()) { 2873 _failures = true; 2874 } 2875 } 2876 }; 2877 2878 void G1CollectedHeap::verify(bool allow_dirty, bool silent) { 2879 verify(allow_dirty, silent, VerifyOption_G1UsePrevMarking); 2880 } 2881 2882 void G1CollectedHeap::verify(bool allow_dirty, 2883 bool silent, 2884 VerifyOption vo) { 2885 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 2886 if (!silent) { gclog_or_tty->print("Roots (excluding permgen) "); } 2887 VerifyRootsClosure rootsCl(vo); 2888 CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false); 2889 2890 // We apply the relevant closures to all the oops in the 2891 // system dictionary, the string table and the code cache. 2892 const int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings | SharedHeap::SO_CodeCache; 2893 2894 process_strong_roots(true, // activate StrongRootsScope 2895 true, // we set "collecting perm gen" to true, 2896 // so we don't reset the dirty cards in the perm gen. 2897 SharedHeap::ScanningOption(so), // roots scanning options 2898 &rootsCl, 2899 &blobsCl, 2900 &rootsCl); 2901 2902 // If we're verifying after the marking phase of a Full GC then we can't 2903 // treat the perm gen as roots into the G1 heap. Some of the objects in 2904 // the perm gen may be dead and hence not marked. If one of these dead 2905 // objects is considered to be a root then we may end up with a false 2906 // "Root location <x> points to dead ob <y>" failure. 2907 if (vo != VerifyOption_G1UseMarkWord) { 2908 // Since we used "collecting_perm_gen" == true above, we will not have 2909 // checked the refs from perm into the G1-collected heap. We check those 2910 // references explicitly below. Whether the relevant cards are dirty 2911 // is checked further below in the rem set verification. 2912 if (!silent) { gclog_or_tty->print("Permgen roots "); } 2913 perm_gen()->oop_iterate(&rootsCl); 2914 } 2915 bool failures = rootsCl.failures(); 2916 2917 if (vo != VerifyOption_G1UseMarkWord) { 2918 // If we're verifying during a full GC then the region sets 2919 // will have been torn down at the start of the GC. Therefore 2920 // verifying the region sets will fail. So we only verify 2921 // the region sets when not in a full GC. 2922 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 2923 verify_region_sets(); 2924 } 2925 2926 if (!silent) { gclog_or_tty->print("HeapRegions "); } 2927 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 2928 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 2929 "sanity check"); 2930 2931 G1ParVerifyTask task(this, allow_dirty, vo); 2932 int n_workers = workers()->total_workers(); 2933 set_par_threads(n_workers); 2934 workers()->run_task(&task); 2935 set_par_threads(0); 2936 if (task.failures()) { 2937 failures = true; 2938 } 2939 2940 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue), 2941 "sanity check"); 2942 2943 reset_heap_region_claim_values(); 2944 2945 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 2946 "sanity check"); 2947 } else { 2948 VerifyRegionClosure blk(allow_dirty, false, vo); 2949 heap_region_iterate(&blk); 2950 if (blk.failures()) { 2951 failures = true; 2952 } 2953 } 2954 if (!silent) gclog_or_tty->print("RemSet "); 2955 rem_set()->verify(); 2956 2957 if (failures) { 2958 gclog_or_tty->print_cr("Heap:"); 2959 print_on(gclog_or_tty, true /* extended */); 2960 gclog_or_tty->print_cr(""); 2961 #ifndef PRODUCT 2962 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 2963 concurrent_mark()->print_reachable("at-verification-failure", 2964 vo, false /* all */); 2965 } 2966 #endif 2967 gclog_or_tty->flush(); 2968 } 2969 guarantee(!failures, "there should not have been any failures"); 2970 } else { 2971 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) "); 2972 } 2973 } 2974 2975 class PrintRegionClosure: public HeapRegionClosure { 2976 outputStream* _st; 2977 public: 2978 PrintRegionClosure(outputStream* st) : _st(st) {} 2979 bool doHeapRegion(HeapRegion* r) { 2980 r->print_on(_st); 2981 return false; 2982 } 2983 }; 2984 2985 void G1CollectedHeap::print() const { print_on(tty); } 2986 2987 void G1CollectedHeap::print_on(outputStream* st) const { 2988 print_on(st, PrintHeapAtGCExtended); 2989 } 2990 2991 void G1CollectedHeap::print_on(outputStream* st, bool extended) const { 2992 st->print(" %-20s", "garbage-first heap"); 2993 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2994 capacity()/K, used_unlocked()/K); 2995 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 2996 _g1_storage.low_boundary(), 2997 _g1_storage.high(), 2998 _g1_storage.high_boundary()); 2999 st->cr(); 3000 st->print(" region size " SIZE_FORMAT "K, ", 3001 HeapRegion::GrainBytes/K); 3002 size_t young_regions = _young_list->length(); 3003 st->print(SIZE_FORMAT " young (" SIZE_FORMAT "K), ", 3004 young_regions, young_regions * HeapRegion::GrainBytes / K); 3005 size_t survivor_regions = g1_policy()->recorded_survivor_regions(); 3006 st->print(SIZE_FORMAT " survivors (" SIZE_FORMAT "K)", 3007 survivor_regions, survivor_regions * HeapRegion::GrainBytes / K); 3008 st->cr(); 3009 perm()->as_gen()->print_on(st); 3010 if (extended) { 3011 st->cr(); 3012 print_on_extended(st); 3013 } 3014 } 3015 3016 void G1CollectedHeap::print_on_extended(outputStream* st) const { 3017 PrintRegionClosure blk(st); 3018 heap_region_iterate(&blk); 3019 } 3020 3021 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3022 if (G1CollectedHeap::use_parallel_gc_threads()) { 3023 workers()->print_worker_threads_on(st); 3024 } 3025 _cmThread->print_on(st); 3026 st->cr(); 3027 _cm->print_worker_threads_on(st); 3028 _cg1r->print_worker_threads_on(st); 3029 st->cr(); 3030 } 3031 3032 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3033 if (G1CollectedHeap::use_parallel_gc_threads()) { 3034 workers()->threads_do(tc); 3035 } 3036 tc->do_thread(_cmThread); 3037 _cg1r->threads_do(tc); 3038 } 3039 3040 void G1CollectedHeap::print_tracing_info() const { 3041 // We'll overload this to mean "trace GC pause statistics." 3042 if (TraceGen0Time || TraceGen1Time) { 3043 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3044 // to that. 3045 g1_policy()->print_tracing_info(); 3046 } 3047 if (G1SummarizeRSetStats) { 3048 g1_rem_set()->print_summary_info(); 3049 } 3050 if (G1SummarizeConcMark) { 3051 concurrent_mark()->print_summary_info(); 3052 } 3053 g1_policy()->print_yg_surv_rate_info(); 3054 SpecializationStats::print(); 3055 } 3056 3057 #ifndef PRODUCT 3058 // Helpful for debugging RSet issues. 3059 3060 class PrintRSetsClosure : public HeapRegionClosure { 3061 private: 3062 const char* _msg; 3063 size_t _occupied_sum; 3064 3065 public: 3066 bool doHeapRegion(HeapRegion* r) { 3067 HeapRegionRemSet* hrrs = r->rem_set(); 3068 size_t occupied = hrrs->occupied(); 3069 _occupied_sum += occupied; 3070 3071 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3072 HR_FORMAT_PARAMS(r)); 3073 if (occupied == 0) { 3074 gclog_or_tty->print_cr(" RSet is empty"); 3075 } else { 3076 hrrs->print(); 3077 } 3078 gclog_or_tty->print_cr("----------"); 3079 return false; 3080 } 3081 3082 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3083 gclog_or_tty->cr(); 3084 gclog_or_tty->print_cr("========================================"); 3085 gclog_or_tty->print_cr(msg); 3086 gclog_or_tty->cr(); 3087 } 3088 3089 ~PrintRSetsClosure() { 3090 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3091 gclog_or_tty->print_cr("========================================"); 3092 gclog_or_tty->cr(); 3093 } 3094 }; 3095 3096 void G1CollectedHeap::print_cset_rsets() { 3097 PrintRSetsClosure cl("Printing CSet RSets"); 3098 collection_set_iterate(&cl); 3099 } 3100 3101 void G1CollectedHeap::print_all_rsets() { 3102 PrintRSetsClosure cl("Printing All RSets");; 3103 heap_region_iterate(&cl); 3104 } 3105 #endif // PRODUCT 3106 3107 G1CollectedHeap* G1CollectedHeap::heap() { 3108 assert(_sh->kind() == CollectedHeap::G1CollectedHeap, 3109 "not a garbage-first heap"); 3110 return _g1h; 3111 } 3112 3113 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3114 // always_do_update_barrier = false; 3115 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3116 // Call allocation profiler 3117 AllocationProfiler::iterate_since_last_gc(); 3118 // Fill TLAB's and such 3119 ensure_parsability(true); 3120 } 3121 3122 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) { 3123 // FIXME: what is this about? 3124 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3125 // is set. 3126 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3127 "derived pointer present")); 3128 // always_do_update_barrier = true; 3129 } 3130 3131 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3132 unsigned int gc_count_before, 3133 bool* succeeded) { 3134 assert_heap_not_locked_and_not_at_safepoint(); 3135 g1_policy()->record_stop_world_start(); 3136 VM_G1IncCollectionPause op(gc_count_before, 3137 word_size, 3138 false, /* should_initiate_conc_mark */ 3139 g1_policy()->max_pause_time_ms(), 3140 GCCause::_g1_inc_collection_pause); 3141 VMThread::execute(&op); 3142 3143 HeapWord* result = op.result(); 3144 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3145 assert(result == NULL || ret_succeeded, 3146 "the result should be NULL if the VM did not succeed"); 3147 *succeeded = ret_succeeded; 3148 3149 assert_heap_not_locked(); 3150 return result; 3151 } 3152 3153 void 3154 G1CollectedHeap::doConcurrentMark() { 3155 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3156 if (!_cmThread->in_progress()) { 3157 _cmThread->set_started(); 3158 CGC_lock->notify(); 3159 } 3160 } 3161 3162 // <NEW PREDICTION> 3163 3164 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr, 3165 bool young) { 3166 return _g1_policy->predict_region_elapsed_time_ms(hr, young); 3167 } 3168 3169 void G1CollectedHeap::check_if_region_is_too_expensive(double 3170 predicted_time_ms) { 3171 _g1_policy->check_if_region_is_too_expensive(predicted_time_ms); 3172 } 3173 3174 size_t G1CollectedHeap::pending_card_num() { 3175 size_t extra_cards = 0; 3176 JavaThread *curr = Threads::first(); 3177 while (curr != NULL) { 3178 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3179 extra_cards += dcq.size(); 3180 curr = curr->next(); 3181 } 3182 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3183 size_t buffer_size = dcqs.buffer_size(); 3184 size_t buffer_num = dcqs.completed_buffers_num(); 3185 return buffer_size * buffer_num + extra_cards; 3186 } 3187 3188 size_t G1CollectedHeap::max_pending_card_num() { 3189 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3190 size_t buffer_size = dcqs.buffer_size(); 3191 size_t buffer_num = dcqs.completed_buffers_num(); 3192 int thread_num = Threads::number_of_threads(); 3193 return (buffer_num + thread_num) * buffer_size; 3194 } 3195 3196 size_t G1CollectedHeap::cards_scanned() { 3197 return g1_rem_set()->cardsScanned(); 3198 } 3199 3200 void 3201 G1CollectedHeap::setup_surviving_young_words() { 3202 guarantee( _surviving_young_words == NULL, "pre-condition" ); 3203 size_t array_length = g1_policy()->young_cset_length(); 3204 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length); 3205 if (_surviving_young_words == NULL) { 3206 vm_exit_out_of_memory(sizeof(size_t) * array_length, 3207 "Not enough space for young surv words summary."); 3208 } 3209 memset(_surviving_young_words, 0, array_length * sizeof(size_t)); 3210 #ifdef ASSERT 3211 for (size_t i = 0; i < array_length; ++i) { 3212 assert( _surviving_young_words[i] == 0, "memset above" ); 3213 } 3214 #endif // !ASSERT 3215 } 3216 3217 void 3218 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3219 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3220 size_t array_length = g1_policy()->young_cset_length(); 3221 for (size_t i = 0; i < array_length; ++i) 3222 _surviving_young_words[i] += surv_young_words[i]; 3223 } 3224 3225 void 3226 G1CollectedHeap::cleanup_surviving_young_words() { 3227 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3228 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words); 3229 _surviving_young_words = NULL; 3230 } 3231 3232 // </NEW PREDICTION> 3233 3234 #ifdef ASSERT 3235 class VerifyCSetClosure: public HeapRegionClosure { 3236 public: 3237 bool doHeapRegion(HeapRegion* hr) { 3238 // Here we check that the CSet region's RSet is ready for parallel 3239 // iteration. The fields that we'll verify are only manipulated 3240 // when the region is part of a CSet and is collected. Afterwards, 3241 // we reset these fields when we clear the region's RSet (when the 3242 // region is freed) so they are ready when the region is 3243 // re-allocated. The only exception to this is if there's an 3244 // evacuation failure and instead of freeing the region we leave 3245 // it in the heap. In that case, we reset these fields during 3246 // evacuation failure handling. 3247 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3248 3249 // Here's a good place to add any other checks we'd like to 3250 // perform on CSet regions. 3251 return false; 3252 } 3253 }; 3254 #endif // ASSERT 3255 3256 #if TASKQUEUE_STATS 3257 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3258 st->print_raw_cr("GC Task Stats"); 3259 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3260 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3261 } 3262 3263 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3264 print_taskqueue_stats_hdr(st); 3265 3266 TaskQueueStats totals; 3267 const int n = workers() != NULL ? workers()->total_workers() : 1; 3268 for (int i = 0; i < n; ++i) { 3269 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3270 totals += task_queue(i)->stats; 3271 } 3272 st->print_raw("tot "); totals.print(st); st->cr(); 3273 3274 DEBUG_ONLY(totals.verify()); 3275 } 3276 3277 void G1CollectedHeap::reset_taskqueue_stats() { 3278 const int n = workers() != NULL ? workers()->total_workers() : 1; 3279 for (int i = 0; i < n; ++i) { 3280 task_queue(i)->stats.reset(); 3281 } 3282 } 3283 #endif // TASKQUEUE_STATS 3284 3285 bool 3286 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3287 assert_at_safepoint(true /* should_be_vm_thread */); 3288 guarantee(!is_gc_active(), "collection is not reentrant"); 3289 3290 if (GC_locker::check_active_before_gc()) { 3291 return false; 3292 } 3293 3294 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3295 ResourceMark rm; 3296 3297 if (PrintHeapAtGC) { 3298 Universe::print_heap_before_gc(); 3299 } 3300 3301 verify_region_sets_optional(); 3302 verify_dirty_young_regions(); 3303 3304 { 3305 // This call will decide whether this pause is an initial-mark 3306 // pause. If it is, during_initial_mark_pause() will return true 3307 // for the duration of this pause. 3308 g1_policy()->decide_on_conc_mark_initiation(); 3309 3310 char verbose_str[128]; 3311 sprintf(verbose_str, "GC pause "); 3312 if (g1_policy()->full_young_gcs()) { 3313 strcat(verbose_str, "(young)"); 3314 } else { 3315 strcat(verbose_str, "(partial)"); 3316 } 3317 if (g1_policy()->during_initial_mark_pause()) { 3318 strcat(verbose_str, " (initial-mark)"); 3319 // We are about to start a marking cycle, so we increment the 3320 // full collection counter. 3321 increment_total_full_collections(); 3322 } 3323 3324 // if PrintGCDetails is on, we'll print long statistics information 3325 // in the collector policy code, so let's not print this as the output 3326 // is messy if we do. 3327 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); 3328 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); 3329 TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty); 3330 3331 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3332 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3333 3334 // If the secondary_free_list is not empty, append it to the 3335 // free_list. No need to wait for the cleanup operation to finish; 3336 // the region allocation code will check the secondary_free_list 3337 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3338 // set, skip this step so that the region allocation code has to 3339 // get entries from the secondary_free_list. 3340 if (!G1StressConcRegionFreeing) { 3341 append_secondary_free_list_if_not_empty_with_lock(); 3342 } 3343 3344 assert(check_young_list_well_formed(), 3345 "young list should be well formed"); 3346 3347 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3348 IsGCActiveMark x; 3349 3350 gc_prologue(false); 3351 increment_total_collections(false /* full gc */); 3352 increment_gc_time_stamp(); 3353 3354 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) { 3355 HandleMark hm; // Discard invalid handles created during verification 3356 gclog_or_tty->print(" VerifyBeforeGC:"); 3357 prepare_for_verify(); 3358 Universe::verify(/* allow dirty */ false, 3359 /* silent */ false, 3360 /* option */ VerifyOption_G1UsePrevMarking); 3361 3362 } 3363 3364 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3365 3366 // Please see comment in G1CollectedHeap::ref_processing_init() 3367 // to see how reference processing currently works in G1. 3368 // 3369 // We want to turn off ref discovery, if necessary, and turn it back on 3370 // on again later if we do. XXX Dubious: why is discovery disabled? 3371 bool was_enabled = ref_processor()->discovery_enabled(); 3372 if (was_enabled) ref_processor()->disable_discovery(); 3373 3374 // Forget the current alloc region (we might even choose it to be part 3375 // of the collection set!). 3376 release_mutator_alloc_region(); 3377 3378 // We should call this after we retire the mutator alloc 3379 // region(s) so that all the ALLOC / RETIRE events are generated 3380 // before the start GC event. 3381 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3382 3383 // The elapsed time induced by the start time below deliberately elides 3384 // the possible verification above. 3385 double start_time_sec = os::elapsedTime(); 3386 size_t start_used_bytes = used(); 3387 3388 #if YOUNG_LIST_VERBOSE 3389 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 3390 _young_list->print(); 3391 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3392 #endif // YOUNG_LIST_VERBOSE 3393 3394 g1_policy()->record_collection_pause_start(start_time_sec, 3395 start_used_bytes); 3396 3397 #if YOUNG_LIST_VERBOSE 3398 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 3399 _young_list->print(); 3400 #endif // YOUNG_LIST_VERBOSE 3401 3402 if (g1_policy()->during_initial_mark_pause()) { 3403 concurrent_mark()->checkpointRootsInitialPre(); 3404 } 3405 perm_gen()->save_marks(); 3406 3407 // We must do this before any possible evacuation that should propagate 3408 // marks. 3409 if (mark_in_progress()) { 3410 double start_time_sec = os::elapsedTime(); 3411 3412 _cm->drainAllSATBBuffers(); 3413 double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0; 3414 g1_policy()->record_satb_drain_time(finish_mark_ms); 3415 } 3416 // Record the number of elements currently on the mark stack, so we 3417 // only iterate over these. (Since evacuation may add to the mark 3418 // stack, doing more exposes race conditions.) If no mark is in 3419 // progress, this will be zero. 3420 _cm->set_oops_do_bound(); 3421 3422 if (mark_in_progress()) { 3423 concurrent_mark()->newCSet(); 3424 } 3425 3426 #if YOUNG_LIST_VERBOSE 3427 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 3428 _young_list->print(); 3429 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3430 #endif // YOUNG_LIST_VERBOSE 3431 3432 g1_policy()->choose_collection_set(target_pause_time_ms); 3433 3434 if (_hr_printer.is_active()) { 3435 HeapRegion* hr = g1_policy()->collection_set(); 3436 while (hr != NULL) { 3437 G1HRPrinter::RegionType type; 3438 if (!hr->is_young()) { 3439 type = G1HRPrinter::Old; 3440 } else if (hr->is_survivor()) { 3441 type = G1HRPrinter::Survivor; 3442 } else { 3443 type = G1HRPrinter::Eden; 3444 } 3445 _hr_printer.cset(hr); 3446 hr = hr->next_in_collection_set(); 3447 } 3448 } 3449 3450 // We have chosen the complete collection set. If marking is 3451 // active then, we clear the region fields of any of the 3452 // concurrent marking tasks whose region fields point into 3453 // the collection set as these values will become stale. This 3454 // will cause the owning marking threads to claim a new region 3455 // when marking restarts. 3456 if (mark_in_progress()) { 3457 concurrent_mark()->reset_active_task_region_fields_in_cset(); 3458 } 3459 3460 #ifdef ASSERT 3461 VerifyCSetClosure cl; 3462 collection_set_iterate(&cl); 3463 #endif // ASSERT 3464 3465 setup_surviving_young_words(); 3466 3467 // Initialize the GC alloc regions. 3468 init_gc_alloc_regions(); 3469 3470 // Actually do the work... 3471 evacuate_collection_set(); 3472 3473 free_collection_set(g1_policy()->collection_set()); 3474 g1_policy()->clear_collection_set(); 3475 3476 cleanup_surviving_young_words(); 3477 3478 // Start a new incremental collection set for the next pause. 3479 g1_policy()->start_incremental_cset_building(); 3480 3481 // Clear the _cset_fast_test bitmap in anticipation of adding 3482 // regions to the incremental collection set for the next 3483 // evacuation pause. 3484 clear_cset_fast_test(); 3485 3486 _young_list->reset_sampled_info(); 3487 3488 // Don't check the whole heap at this point as the 3489 // GC alloc regions from this pause have been tagged 3490 // as survivors and moved on to the survivor list. 3491 // Survivor regions will fail the !is_young() check. 3492 assert(check_young_list_empty(false /* check_heap */), 3493 "young list should be empty"); 3494 3495 #if YOUNG_LIST_VERBOSE 3496 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 3497 _young_list->print(); 3498 #endif // YOUNG_LIST_VERBOSE 3499 3500 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 3501 _young_list->first_survivor_region(), 3502 _young_list->last_survivor_region()); 3503 3504 _young_list->reset_auxilary_lists(); 3505 3506 if (evacuation_failed()) { 3507 _summary_bytes_used = recalculate_used(); 3508 } else { 3509 // The "used" of the the collection set have already been subtracted 3510 // when they were freed. Add in the bytes evacuated. 3511 _summary_bytes_used += g1_policy()->bytes_copied_during_gc(); 3512 } 3513 3514 if (g1_policy()->during_initial_mark_pause()) { 3515 concurrent_mark()->checkpointRootsInitialPost(); 3516 set_marking_started(); 3517 // CAUTION: after the doConcurrentMark() call below, 3518 // the concurrent marking thread(s) could be running 3519 // concurrently with us. Make sure that anything after 3520 // this point does not assume that we are the only GC thread 3521 // running. Note: of course, the actual marking work will 3522 // not start until the safepoint itself is released in 3523 // ConcurrentGCThread::safepoint_desynchronize(). 3524 doConcurrentMark(); 3525 } 3526 3527 allocate_dummy_regions(); 3528 3529 #if YOUNG_LIST_VERBOSE 3530 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 3531 _young_list->print(); 3532 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3533 #endif // YOUNG_LIST_VERBOSE 3534 3535 init_mutator_alloc_region(); 3536 3537 double end_time_sec = os::elapsedTime(); 3538 double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS; 3539 g1_policy()->record_pause_time_ms(pause_time_ms); 3540 g1_policy()->record_collection_pause_end(); 3541 3542 MemoryService::track_memory_usage(); 3543 3544 // In prepare_for_verify() below we'll need to scan the deferred 3545 // update buffers to bring the RSets up-to-date if 3546 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 3547 // the update buffers we'll probably need to scan cards on the 3548 // regions we just allocated to (i.e., the GC alloc 3549 // regions). However, during the last GC we called 3550 // set_saved_mark() on all the GC alloc regions, so card 3551 // scanning might skip the [saved_mark_word()...top()] area of 3552 // those regions (i.e., the area we allocated objects into 3553 // during the last GC). But it shouldn't. Given that 3554 // saved_mark_word() is conditional on whether the GC time stamp 3555 // on the region is current or not, by incrementing the GC time 3556 // stamp here we invalidate all the GC time stamps on all the 3557 // regions and saved_mark_word() will simply return top() for 3558 // all the regions. This is a nicer way of ensuring this rather 3559 // than iterating over the regions and fixing them. In fact, the 3560 // GC time stamp increment here also ensures that 3561 // saved_mark_word() will return top() between pauses, i.e., 3562 // during concurrent refinement. So we don't need the 3563 // is_gc_active() check to decided which top to use when 3564 // scanning cards (see CR 7039627). 3565 increment_gc_time_stamp(); 3566 3567 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) { 3568 HandleMark hm; // Discard invalid handles created during verification 3569 gclog_or_tty->print(" VerifyAfterGC:"); 3570 prepare_for_verify(); 3571 Universe::verify(/* allow dirty */ true, 3572 /* silent */ false, 3573 /* option */ VerifyOption_G1UsePrevMarking); 3574 } 3575 3576 if (was_enabled) ref_processor()->enable_discovery(); 3577 3578 { 3579 size_t expand_bytes = g1_policy()->expansion_amount(); 3580 if (expand_bytes > 0) { 3581 size_t bytes_before = capacity(); 3582 if (!expand(expand_bytes)) { 3583 // We failed to expand the heap so let's verify that 3584 // committed/uncommitted amount match the backing store 3585 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch"); 3586 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch"); 3587 } 3588 } 3589 } 3590 3591 // We should do this after we potentially expand the heap so 3592 // that all the COMMIT events are generated before the end GC 3593 // event, and after we retire the GC alloc regions so that all 3594 // RETIRE events are generated before the end GC event. 3595 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 3596 3597 // We have to do this after we decide whether to expand the heap or not. 3598 g1_policy()->print_heap_transition(); 3599 3600 if (mark_in_progress()) { 3601 concurrent_mark()->update_g1_committed(); 3602 } 3603 3604 #ifdef TRACESPINNING 3605 ParallelTaskTerminator::print_termination_counts(); 3606 #endif 3607 3608 gc_epilogue(false); 3609 } 3610 3611 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) { 3612 gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum); 3613 print_tracing_info(); 3614 vm_exit(-1); 3615 } 3616 } 3617 3618 _hrs.verify_optional(); 3619 verify_region_sets_optional(); 3620 3621 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats()); 3622 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3623 3624 if (PrintHeapAtGC) { 3625 Universe::print_heap_after_gc(); 3626 } 3627 g1mm()->update_counters(); 3628 3629 if (G1SummarizeRSetStats && 3630 (G1SummarizeRSetStatsPeriod > 0) && 3631 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3632 g1_rem_set()->print_summary_info(); 3633 } 3634 3635 return true; 3636 } 3637 3638 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose) 3639 { 3640 size_t gclab_word_size; 3641 switch (purpose) { 3642 case GCAllocForSurvived: 3643 gclab_word_size = YoungPLABSize; 3644 break; 3645 case GCAllocForTenured: 3646 gclab_word_size = OldPLABSize; 3647 break; 3648 default: 3649 assert(false, "unknown GCAllocPurpose"); 3650 gclab_word_size = OldPLABSize; 3651 break; 3652 } 3653 return gclab_word_size; 3654 } 3655 3656 void G1CollectedHeap::init_mutator_alloc_region() { 3657 assert(_mutator_alloc_region.get() == NULL, "pre-condition"); 3658 _mutator_alloc_region.init(); 3659 } 3660 3661 void G1CollectedHeap::release_mutator_alloc_region() { 3662 _mutator_alloc_region.release(); 3663 assert(_mutator_alloc_region.get() == NULL, "post-condition"); 3664 } 3665 3666 void G1CollectedHeap::init_gc_alloc_regions() { 3667 assert_at_safepoint(true /* should_be_vm_thread */); 3668 3669 _survivor_gc_alloc_region.init(); 3670 _old_gc_alloc_region.init(); 3671 HeapRegion* retained_region = _retained_old_gc_alloc_region; 3672 _retained_old_gc_alloc_region = NULL; 3673 3674 // We will discard the current GC alloc region if: 3675 // a) it's in the collection set (it can happen!), 3676 // b) it's already full (no point in using it), 3677 // c) it's empty (this means that it was emptied during 3678 // a cleanup and it should be on the free list now), or 3679 // d) it's humongous (this means that it was emptied 3680 // during a cleanup and was added to the free list, but 3681 // has been subseqently used to allocate a humongous 3682 // object that may be less than the region size). 3683 if (retained_region != NULL && 3684 !retained_region->in_collection_set() && 3685 !(retained_region->top() == retained_region->end()) && 3686 !retained_region->is_empty() && 3687 !retained_region->isHumongous()) { 3688 retained_region->set_saved_mark(); 3689 _old_gc_alloc_region.set(retained_region); 3690 _hr_printer.reuse(retained_region); 3691 } 3692 } 3693 3694 void G1CollectedHeap::release_gc_alloc_regions() { 3695 _survivor_gc_alloc_region.release(); 3696 // If we have an old GC alloc region to release, we'll save it in 3697 // _retained_old_gc_alloc_region. If we don't 3698 // _retained_old_gc_alloc_region will become NULL. This is what we 3699 // want either way so no reason to check explicitly for either 3700 // condition. 3701 _retained_old_gc_alloc_region = _old_gc_alloc_region.release(); 3702 } 3703 3704 void G1CollectedHeap::abandon_gc_alloc_regions() { 3705 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition"); 3706 assert(_old_gc_alloc_region.get() == NULL, "pre-condition"); 3707 _retained_old_gc_alloc_region = NULL; 3708 } 3709 3710 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 3711 _drain_in_progress = false; 3712 set_evac_failure_closure(cl); 3713 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true); 3714 } 3715 3716 void G1CollectedHeap::finalize_for_evac_failure() { 3717 assert(_evac_failure_scan_stack != NULL && 3718 _evac_failure_scan_stack->length() == 0, 3719 "Postcondition"); 3720 assert(!_drain_in_progress, "Postcondition"); 3721 delete _evac_failure_scan_stack; 3722 _evac_failure_scan_stack = NULL; 3723 } 3724 3725 // *** Sequential G1 Evacuation 3726 3727 class G1IsAliveClosure: public BoolObjectClosure { 3728 G1CollectedHeap* _g1; 3729 public: 3730 G1IsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 3731 void do_object(oop p) { assert(false, "Do not call."); } 3732 bool do_object_b(oop p) { 3733 // It is reachable if it is outside the collection set, or is inside 3734 // and forwarded. 3735 3736 #ifdef G1_DEBUG 3737 gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d", 3738 (void*) p, _g1->obj_in_cs(p), p->is_forwarded(), 3739 !_g1->obj_in_cs(p) || p->is_forwarded()); 3740 #endif // G1_DEBUG 3741 3742 return !_g1->obj_in_cs(p) || p->is_forwarded(); 3743 } 3744 }; 3745 3746 class G1KeepAliveClosure: public OopClosure { 3747 G1CollectedHeap* _g1; 3748 public: 3749 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 3750 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3751 void do_oop( oop* p) { 3752 oop obj = *p; 3753 #ifdef G1_DEBUG 3754 if (PrintGC && Verbose) { 3755 gclog_or_tty->print_cr("keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT, 3756 p, (void*) obj, (void*) *p); 3757 } 3758 #endif // G1_DEBUG 3759 3760 if (_g1->obj_in_cs(obj)) { 3761 assert( obj->is_forwarded(), "invariant" ); 3762 *p = obj->forwardee(); 3763 #ifdef G1_DEBUG 3764 gclog_or_tty->print_cr(" in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT, 3765 (void*) obj, (void*) *p); 3766 #endif // G1_DEBUG 3767 } 3768 } 3769 }; 3770 3771 class UpdateRSetDeferred : public OopsInHeapRegionClosure { 3772 private: 3773 G1CollectedHeap* _g1; 3774 DirtyCardQueue *_dcq; 3775 CardTableModRefBS* _ct_bs; 3776 3777 public: 3778 UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) : 3779 _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {} 3780 3781 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3782 virtual void do_oop( oop* p) { do_oop_work(p); } 3783 template <class T> void do_oop_work(T* p) { 3784 assert(_from->is_in_reserved(p), "paranoia"); 3785 if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && 3786 !_from->is_survivor()) { 3787 size_t card_index = _ct_bs->index_for(p); 3788 if (_ct_bs->mark_card_deferred(card_index)) { 3789 _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index)); 3790 } 3791 } 3792 } 3793 }; 3794 3795 class RemoveSelfPointerClosure: public ObjectClosure { 3796 private: 3797 G1CollectedHeap* _g1; 3798 ConcurrentMark* _cm; 3799 HeapRegion* _hr; 3800 size_t _prev_marked_bytes; 3801 size_t _next_marked_bytes; 3802 OopsInHeapRegionClosure *_cl; 3803 public: 3804 RemoveSelfPointerClosure(G1CollectedHeap* g1, HeapRegion* hr, 3805 OopsInHeapRegionClosure* cl) : 3806 _g1(g1), _hr(hr), _cm(_g1->concurrent_mark()), _prev_marked_bytes(0), 3807 _next_marked_bytes(0), _cl(cl) {} 3808 3809 size_t prev_marked_bytes() { return _prev_marked_bytes; } 3810 size_t next_marked_bytes() { return _next_marked_bytes; } 3811 3812 // <original comment> 3813 // The original idea here was to coalesce evacuated and dead objects. 3814 // However that caused complications with the block offset table (BOT). 3815 // In particular if there were two TLABs, one of them partially refined. 3816 // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~| 3817 // The BOT entries of the unrefined part of TLAB_2 point to the start 3818 // of TLAB_2. If the last object of the TLAB_1 and the first object 3819 // of TLAB_2 are coalesced, then the cards of the unrefined part 3820 // would point into middle of the filler object. 3821 // The current approach is to not coalesce and leave the BOT contents intact. 3822 // </original comment> 3823 // 3824 // We now reset the BOT when we start the object iteration over the 3825 // region and refine its entries for every object we come across. So 3826 // the above comment is not really relevant and we should be able 3827 // to coalesce dead objects if we want to. 3828 void do_object(oop obj) { 3829 HeapWord* obj_addr = (HeapWord*) obj; 3830 assert(_hr->is_in(obj_addr), "sanity"); 3831 size_t obj_size = obj->size(); 3832 _hr->update_bot_for_object(obj_addr, obj_size); 3833 if (obj->is_forwarded() && obj->forwardee() == obj) { 3834 // The object failed to move. 3835 assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs."); 3836 _cm->markPrev(obj); 3837 assert(_cm->isPrevMarked(obj), "Should be marked!"); 3838 _prev_marked_bytes += (obj_size * HeapWordSize); 3839 if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) { 3840 _cm->markAndGrayObjectIfNecessary(obj); 3841 } 3842 obj->set_mark(markOopDesc::prototype()); 3843 // While we were processing RSet buffers during the 3844 // collection, we actually didn't scan any cards on the 3845 // collection set, since we didn't want to update remebered 3846 // sets with entries that point into the collection set, given 3847 // that live objects fromthe collection set are about to move 3848 // and such entries will be stale very soon. This change also 3849 // dealt with a reliability issue which involved scanning a 3850 // card in the collection set and coming across an array that 3851 // was being chunked and looking malformed. The problem is 3852 // that, if evacuation fails, we might have remembered set 3853 // entries missing given that we skipped cards on the 3854 // collection set. So, we'll recreate such entries now. 3855 obj->oop_iterate(_cl); 3856 assert(_cm->isPrevMarked(obj), "Should be marked!"); 3857 } else { 3858 // The object has been either evacuated or is dead. Fill it with a 3859 // dummy object. 3860 MemRegion mr((HeapWord*)obj, obj_size); 3861 CollectedHeap::fill_with_object(mr); 3862 _cm->clearRangeBothMaps(mr); 3863 } 3864 } 3865 }; 3866 3867 void G1CollectedHeap::remove_self_forwarding_pointers() { 3868 UpdateRSetImmediate immediate_update(_g1h->g1_rem_set()); 3869 DirtyCardQueue dcq(&_g1h->dirty_card_queue_set()); 3870 UpdateRSetDeferred deferred_update(_g1h, &dcq); 3871 OopsInHeapRegionClosure *cl; 3872 if (G1DeferredRSUpdate) { 3873 cl = &deferred_update; 3874 } else { 3875 cl = &immediate_update; 3876 } 3877 HeapRegion* cur = g1_policy()->collection_set(); 3878 while (cur != NULL) { 3879 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!"); 3880 assert(!cur->isHumongous(), "sanity"); 3881 3882 if (cur->evacuation_failed()) { 3883 assert(cur->in_collection_set(), "bad CS"); 3884 RemoveSelfPointerClosure rspc(_g1h, cur, cl); 3885 3886 // In the common case we make sure that this is done when the 3887 // region is freed so that it is "ready-to-go" when it's 3888 // re-allocated. However, when evacuation failure happens, a 3889 // region will remain in the heap and might ultimately be added 3890 // to a CSet in the future. So we have to be careful here and 3891 // make sure the region's RSet is ready for parallel iteration 3892 // whenever this might be required in the future. 3893 cur->rem_set()->reset_for_par_iteration(); 3894 cur->reset_bot(); 3895 cl->set_region(cur); 3896 cur->object_iterate(&rspc); 3897 3898 // A number of manipulations to make the TAMS be the current top, 3899 // and the marked bytes be the ones observed in the iteration. 3900 if (_g1h->concurrent_mark()->at_least_one_mark_complete()) { 3901 // The comments below are the postconditions achieved by the 3902 // calls. Note especially the last such condition, which says that 3903 // the count of marked bytes has been properly restored. 3904 cur->note_start_of_marking(false); 3905 // _next_top_at_mark_start == top, _next_marked_bytes == 0 3906 cur->add_to_marked_bytes(rspc.prev_marked_bytes()); 3907 // _next_marked_bytes == prev_marked_bytes. 3908 cur->note_end_of_marking(); 3909 // _prev_top_at_mark_start == top(), 3910 // _prev_marked_bytes == prev_marked_bytes 3911 } 3912 // If there is no mark in progress, we modified the _next variables 3913 // above needlessly, but harmlessly. 3914 if (_g1h->mark_in_progress()) { 3915 cur->note_start_of_marking(false); 3916 // _next_top_at_mark_start == top, _next_marked_bytes == 0 3917 // _next_marked_bytes == next_marked_bytes. 3918 } 3919 3920 // Now make sure the region has the right index in the sorted array. 3921 g1_policy()->note_change_in_marked_bytes(cur); 3922 } 3923 cur = cur->next_in_collection_set(); 3924 } 3925 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!"); 3926 3927 // Now restore saved marks, if any. 3928 if (_objs_with_preserved_marks != NULL) { 3929 assert(_preserved_marks_of_objs != NULL, "Both or none."); 3930 guarantee(_objs_with_preserved_marks->length() == 3931 _preserved_marks_of_objs->length(), "Both or none."); 3932 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) { 3933 oop obj = _objs_with_preserved_marks->at(i); 3934 markOop m = _preserved_marks_of_objs->at(i); 3935 obj->set_mark(m); 3936 } 3937 // Delete the preserved marks growable arrays (allocated on the C heap). 3938 delete _objs_with_preserved_marks; 3939 delete _preserved_marks_of_objs; 3940 _objs_with_preserved_marks = NULL; 3941 _preserved_marks_of_objs = NULL; 3942 } 3943 } 3944 3945 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 3946 _evac_failure_scan_stack->push(obj); 3947 } 3948 3949 void G1CollectedHeap::drain_evac_failure_scan_stack() { 3950 assert(_evac_failure_scan_stack != NULL, "precondition"); 3951 3952 while (_evac_failure_scan_stack->length() > 0) { 3953 oop obj = _evac_failure_scan_stack->pop(); 3954 _evac_failure_closure->set_region(heap_region_containing(obj)); 3955 obj->oop_iterate_backwards(_evac_failure_closure); 3956 } 3957 } 3958 3959 oop 3960 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, 3961 oop old) { 3962 assert(obj_in_cs(old), 3963 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 3964 (HeapWord*) old)); 3965 markOop m = old->mark(); 3966 oop forward_ptr = old->forward_to_atomic(old); 3967 if (forward_ptr == NULL) { 3968 // Forward-to-self succeeded. 3969 if (_evac_failure_closure != cl) { 3970 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 3971 assert(!_drain_in_progress, 3972 "Should only be true while someone holds the lock."); 3973 // Set the global evac-failure closure to the current thread's. 3974 assert(_evac_failure_closure == NULL, "Or locking has failed."); 3975 set_evac_failure_closure(cl); 3976 // Now do the common part. 3977 handle_evacuation_failure_common(old, m); 3978 // Reset to NULL. 3979 set_evac_failure_closure(NULL); 3980 } else { 3981 // The lock is already held, and this is recursive. 3982 assert(_drain_in_progress, "This should only be the recursive case."); 3983 handle_evacuation_failure_common(old, m); 3984 } 3985 return old; 3986 } else { 3987 // Forward-to-self failed. Either someone else managed to allocate 3988 // space for this object (old != forward_ptr) or they beat us in 3989 // self-forwarding it (old == forward_ptr). 3990 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 3991 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 3992 "should not be in the CSet", 3993 (HeapWord*) old, (HeapWord*) forward_ptr)); 3994 return forward_ptr; 3995 } 3996 } 3997 3998 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 3999 set_evacuation_failed(true); 4000 4001 preserve_mark_if_necessary(old, m); 4002 4003 HeapRegion* r = heap_region_containing(old); 4004 if (!r->evacuation_failed()) { 4005 r->set_evacuation_failed(true); 4006 _hr_printer.evac_failure(r); 4007 } 4008 4009 push_on_evac_failure_scan_stack(old); 4010 4011 if (!_drain_in_progress) { 4012 // prevent recursion in copy_to_survivor_space() 4013 _drain_in_progress = true; 4014 drain_evac_failure_scan_stack(); 4015 _drain_in_progress = false; 4016 } 4017 } 4018 4019 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4020 assert(evacuation_failed(), "Oversaving!"); 4021 // We want to call the "for_promotion_failure" version only in the 4022 // case of a promotion failure. 4023 if (m->must_be_preserved_for_promotion_failure(obj)) { 4024 if (_objs_with_preserved_marks == NULL) { 4025 assert(_preserved_marks_of_objs == NULL, "Both or none."); 4026 _objs_with_preserved_marks = 4027 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true); 4028 _preserved_marks_of_objs = 4029 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true); 4030 } 4031 _objs_with_preserved_marks->push(obj); 4032 _preserved_marks_of_objs->push(m); 4033 } 4034 } 4035 4036 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose, 4037 size_t word_size) { 4038 if (purpose == GCAllocForSurvived) { 4039 HeapWord* result = survivor_attempt_allocation(word_size); 4040 if (result != NULL) { 4041 return result; 4042 } else { 4043 // Let's try to allocate in the old gen in case we can fit the 4044 // object there. 4045 return old_attempt_allocation(word_size); 4046 } 4047 } else { 4048 assert(purpose == GCAllocForTenured, "sanity"); 4049 HeapWord* result = old_attempt_allocation(word_size); 4050 if (result != NULL) { 4051 return result; 4052 } else { 4053 // Let's try to allocate in the survivors in case we can fit the 4054 // object there. 4055 return survivor_attempt_allocation(word_size); 4056 } 4057 } 4058 4059 ShouldNotReachHere(); 4060 // Trying to keep some compilers happy. 4061 return NULL; 4062 } 4063 4064 #ifndef PRODUCT 4065 bool GCLabBitMapClosure::do_bit(size_t offset) { 4066 HeapWord* addr = _bitmap->offsetToHeapWord(offset); 4067 guarantee(_cm->isMarked(oop(addr)), "it should be!"); 4068 return true; 4069 } 4070 #endif // PRODUCT 4071 4072 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) : 4073 ParGCAllocBuffer(gclab_word_size), 4074 _should_mark_objects(false), 4075 _bitmap(G1CollectedHeap::heap()->reserved_region().start(), gclab_word_size), 4076 _retired(false) 4077 { 4078 //_should_mark_objects is set to true when G1ParCopyHelper needs to 4079 // mark the forwarded location of an evacuated object. 4080 // We set _should_mark_objects to true if marking is active, i.e. when we 4081 // need to propagate a mark, or during an initial mark pause, i.e. when we 4082 // need to mark objects immediately reachable by the roots. 4083 if (G1CollectedHeap::heap()->mark_in_progress() || 4084 G1CollectedHeap::heap()->g1_policy()->during_initial_mark_pause()) { 4085 _should_mark_objects = true; 4086 } 4087 } 4088 4089 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num) 4090 : _g1h(g1h), 4091 _refs(g1h->task_queue(queue_num)), 4092 _dcq(&g1h->dirty_card_queue_set()), 4093 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()), 4094 _g1_rem(g1h->g1_rem_set()), 4095 _hash_seed(17), _queue_num(queue_num), 4096 _term_attempts(0), 4097 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)), 4098 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)), 4099 _age_table(false), 4100 _strong_roots_time(0), _term_time(0), 4101 _alloc_buffer_waste(0), _undo_waste(0) 4102 { 4103 // we allocate G1YoungSurvRateNumRegions plus one entries, since 4104 // we "sacrifice" entry 0 to keep track of surviving bytes for 4105 // non-young regions (where the age is -1) 4106 // We also add a few elements at the beginning and at the end in 4107 // an attempt to eliminate cache contention 4108 size_t real_length = 1 + _g1h->g1_policy()->young_cset_length(); 4109 size_t array_length = PADDING_ELEM_NUM + 4110 real_length + 4111 PADDING_ELEM_NUM; 4112 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length); 4113 if (_surviving_young_words_base == NULL) 4114 vm_exit_out_of_memory(array_length * sizeof(size_t), 4115 "Not enough space for young surv histo."); 4116 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM; 4117 memset(_surviving_young_words, 0, real_length * sizeof(size_t)); 4118 4119 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer; 4120 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer; 4121 4122 _start = os::elapsedTime(); 4123 } 4124 4125 void 4126 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st) 4127 { 4128 st->print_raw_cr("GC Termination Stats"); 4129 st->print_raw_cr(" elapsed --strong roots-- -------termination-------" 4130 " ------waste (KiB)------"); 4131 st->print_raw_cr("thr ms ms % ms % attempts" 4132 " total alloc undo"); 4133 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------" 4134 " ------- ------- -------"); 4135 } 4136 4137 void 4138 G1ParScanThreadState::print_termination_stats(int i, 4139 outputStream* const st) const 4140 { 4141 const double elapsed_ms = elapsed_time() * 1000.0; 4142 const double s_roots_ms = strong_roots_time() * 1000.0; 4143 const double term_ms = term_time() * 1000.0; 4144 st->print_cr("%3d %9.2f %9.2f %6.2f " 4145 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 4146 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 4147 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms, 4148 term_ms, term_ms * 100 / elapsed_ms, term_attempts(), 4149 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K, 4150 alloc_buffer_waste() * HeapWordSize / K, 4151 undo_waste() * HeapWordSize / K); 4152 } 4153 4154 #ifdef ASSERT 4155 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const { 4156 assert(ref != NULL, "invariant"); 4157 assert(UseCompressedOops, "sanity"); 4158 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref)); 4159 oop p = oopDesc::load_decode_heap_oop(ref); 4160 assert(_g1h->is_in_g1_reserved(p), 4161 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p))); 4162 return true; 4163 } 4164 4165 bool G1ParScanThreadState::verify_ref(oop* ref) const { 4166 assert(ref != NULL, "invariant"); 4167 if (has_partial_array_mask(ref)) { 4168 // Must be in the collection set--it's already been copied. 4169 oop p = clear_partial_array_mask(ref); 4170 assert(_g1h->obj_in_cs(p), 4171 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p))); 4172 } else { 4173 oop p = oopDesc::load_decode_heap_oop(ref); 4174 assert(_g1h->is_in_g1_reserved(p), 4175 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p))); 4176 } 4177 return true; 4178 } 4179 4180 bool G1ParScanThreadState::verify_task(StarTask ref) const { 4181 if (ref.is_narrow()) { 4182 return verify_ref((narrowOop*) ref); 4183 } else { 4184 return verify_ref((oop*) ref); 4185 } 4186 } 4187 #endif // ASSERT 4188 4189 void G1ParScanThreadState::trim_queue() { 4190 StarTask ref; 4191 do { 4192 // Drain the overflow stack first, so other threads can steal. 4193 while (refs()->pop_overflow(ref)) { 4194 deal_with_reference(ref); 4195 } 4196 while (refs()->pop_local(ref)) { 4197 deal_with_reference(ref); 4198 } 4199 } while (!refs()->is_empty()); 4200 } 4201 4202 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) : 4203 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()), 4204 _par_scan_state(par_scan_state), 4205 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()), 4206 _mark_in_progress(_g1->mark_in_progress()) { } 4207 4208 template <class T> void G1ParCopyHelper::mark_object(T* p) { 4209 // This is called from do_oop_work for objects that are not 4210 // in the collection set. Objects in the collection set 4211 // are marked after they have been evacuated. 4212 4213 T heap_oop = oopDesc::load_heap_oop(p); 4214 if (!oopDesc::is_null(heap_oop)) { 4215 oop obj = oopDesc::decode_heap_oop(heap_oop); 4216 HeapWord* addr = (HeapWord*)obj; 4217 if (_g1->is_in_g1_reserved(addr)) { 4218 _cm->grayRoot(oop(addr)); 4219 } 4220 } 4221 } 4222 4223 oop G1ParCopyHelper::copy_to_survivor_space(oop old, bool should_mark_copy) { 4224 size_t word_sz = old->size(); 4225 HeapRegion* from_region = _g1->heap_region_containing_raw(old); 4226 // +1 to make the -1 indexes valid... 4227 int young_index = from_region->young_index_in_cset()+1; 4228 assert( (from_region->is_young() && young_index > 0) || 4229 (!from_region->is_young() && young_index == 0), "invariant" ); 4230 G1CollectorPolicy* g1p = _g1->g1_policy(); 4231 markOop m = old->mark(); 4232 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age() 4233 : m->age(); 4234 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age, 4235 word_sz); 4236 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz); 4237 oop obj = oop(obj_ptr); 4238 4239 if (obj_ptr == NULL) { 4240 // This will either forward-to-self, or detect that someone else has 4241 // installed a forwarding pointer. 4242 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4243 return _g1->handle_evacuation_failure_par(cl, old); 4244 } 4245 4246 // We're going to allocate linearly, so might as well prefetch ahead. 4247 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes); 4248 4249 oop forward_ptr = old->forward_to_atomic(obj); 4250 if (forward_ptr == NULL) { 4251 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz); 4252 if (g1p->track_object_age(alloc_purpose)) { 4253 // We could simply do obj->incr_age(). However, this causes a 4254 // performance issue. obj->incr_age() will first check whether 4255 // the object has a displaced mark by checking its mark word; 4256 // getting the mark word from the new location of the object 4257 // stalls. So, given that we already have the mark word and we 4258 // are about to install it anyway, it's better to increase the 4259 // age on the mark word, when the object does not have a 4260 // displaced mark word. We're not expecting many objects to have 4261 // a displaced marked word, so that case is not optimized 4262 // further (it could be...) and we simply call obj->incr_age(). 4263 4264 if (m->has_displaced_mark_helper()) { 4265 // in this case, we have to install the mark word first, 4266 // otherwise obj looks to be forwarded (the old mark word, 4267 // which contains the forward pointer, was copied) 4268 obj->set_mark(m); 4269 obj->incr_age(); 4270 } else { 4271 m = m->incr_age(); 4272 obj->set_mark(m); 4273 } 4274 _par_scan_state->age_table()->add(obj, word_sz); 4275 } else { 4276 obj->set_mark(m); 4277 } 4278 4279 // Mark the evacuated object or propagate "next" mark bit 4280 if (should_mark_copy) { 4281 if (!use_local_bitmaps || 4282 !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) { 4283 // if we couldn't mark it on the local bitmap (this happens when 4284 // the object was not allocated in the GCLab), we have to bite 4285 // the bullet and do the standard parallel mark 4286 _cm->markAndGrayObjectIfNecessary(obj); 4287 } 4288 4289 if (_g1->isMarkedNext(old)) { 4290 // Unmark the object's old location so that marking 4291 // doesn't think the old object is alive. 4292 _cm->nextMarkBitMap()->parClear((HeapWord*)old); 4293 } 4294 } 4295 4296 size_t* surv_young_words = _par_scan_state->surviving_young_words(); 4297 surv_young_words[young_index] += word_sz; 4298 4299 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) { 4300 arrayOop(old)->set_length(0); 4301 oop* old_p = set_partial_array_mask(old); 4302 _par_scan_state->push_on_queue(old_p); 4303 } else { 4304 // No point in using the slower heap_region_containing() method, 4305 // given that we know obj is in the heap. 4306 _scanner->set_region(_g1->heap_region_containing_raw(obj)); 4307 obj->oop_iterate_backwards(_scanner); 4308 } 4309 } else { 4310 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz); 4311 obj = forward_ptr; 4312 } 4313 return obj; 4314 } 4315 4316 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object> 4317 template <class T> 4318 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object> 4319 ::do_oop_work(T* p) { 4320 oop obj = oopDesc::load_decode_heap_oop(p); 4321 assert(barrier != G1BarrierRS || obj != NULL, 4322 "Precondition: G1BarrierRS implies obj is nonNull"); 4323 4324 // Marking: 4325 // If the object is in the collection set, then the thread 4326 // that copies the object should mark, or propagate the 4327 // mark to, the evacuated object. 4328 // If the object is not in the collection set then we 4329 // should call the mark_object() method depending on the 4330 // value of the template parameter do_mark_object (which will 4331 // be true for root scanning closures during an initial mark 4332 // pause). 4333 // The mark_object() method first checks whether the object 4334 // is marked and, if not, attempts to mark the object. 4335 4336 // here the null check is implicit in the cset_fast_test() test 4337 if (_g1->in_cset_fast_test(obj)) { 4338 if (obj->is_forwarded()) { 4339 oopDesc::encode_store_heap_oop(p, obj->forwardee()); 4340 // If we are a root scanning closure during an initial 4341 // mark pause (i.e. do_mark_object will be true) then 4342 // we also need to handle marking of roots in the 4343 // event of an evacuation failure. In the event of an 4344 // evacuation failure, the object is forwarded to itself 4345 // and not copied so let's mark it here. 4346 if (do_mark_object && obj->forwardee() == obj) { 4347 mark_object(p); 4348 } 4349 } else { 4350 // We need to mark the copied object if we're a root scanning 4351 // closure during an initial mark pause (i.e. do_mark_object 4352 // will be true), or the object is already marked and we need 4353 // to propagate the mark to the evacuated copy. 4354 bool should_mark_copy = do_mark_object || 4355 _during_initial_mark || 4356 (_mark_in_progress && !_g1->is_obj_ill(obj)); 4357 4358 oop copy_oop = copy_to_survivor_space(obj, should_mark_copy); 4359 oopDesc::encode_store_heap_oop(p, copy_oop); 4360 } 4361 // When scanning the RS, we only care about objs in CS. 4362 if (barrier == G1BarrierRS) { 4363 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num()); 4364 } 4365 } else { 4366 // The object is not in collection set. If we're a root scanning 4367 // closure during an initial mark pause (i.e. do_mark_object will 4368 // be true) then attempt to mark the object. 4369 if (do_mark_object) { 4370 mark_object(p); 4371 } 4372 } 4373 4374 if (barrier == G1BarrierEvac && obj != NULL) { 4375 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num()); 4376 } 4377 4378 if (do_gen_barrier && obj != NULL) { 4379 par_do_barrier(p); 4380 } 4381 } 4382 4383 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p); 4384 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p); 4385 4386 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) { 4387 assert(has_partial_array_mask(p), "invariant"); 4388 oop old = clear_partial_array_mask(p); 4389 assert(old->is_objArray(), "must be obj array"); 4390 assert(old->is_forwarded(), "must be forwarded"); 4391 assert(Universe::heap()->is_in_reserved(old), "must be in heap."); 4392 4393 objArrayOop obj = objArrayOop(old->forwardee()); 4394 assert((void*)old != (void*)old->forwardee(), "self forwarding here?"); 4395 // Process ParGCArrayScanChunk elements now 4396 // and push the remainder back onto queue 4397 int start = arrayOop(old)->length(); 4398 int end = obj->length(); 4399 int remainder = end - start; 4400 assert(start <= end, "just checking"); 4401 if (remainder > 2 * ParGCArrayScanChunk) { 4402 // Test above combines last partial chunk with a full chunk 4403 end = start + ParGCArrayScanChunk; 4404 arrayOop(old)->set_length(end); 4405 // Push remainder. 4406 oop* old_p = set_partial_array_mask(old); 4407 assert(arrayOop(old)->length() < obj->length(), "Empty push?"); 4408 _par_scan_state->push_on_queue(old_p); 4409 } else { 4410 // Restore length so that the heap remains parsable in 4411 // case of evacuation failure. 4412 arrayOop(old)->set_length(end); 4413 } 4414 _scanner.set_region(_g1->heap_region_containing_raw(obj)); 4415 // process our set of indices (include header in first chunk) 4416 obj->oop_iterate_range(&_scanner, start, end); 4417 } 4418 4419 class G1ParEvacuateFollowersClosure : public VoidClosure { 4420 protected: 4421 G1CollectedHeap* _g1h; 4422 G1ParScanThreadState* _par_scan_state; 4423 RefToScanQueueSet* _queues; 4424 ParallelTaskTerminator* _terminator; 4425 4426 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4427 RefToScanQueueSet* queues() { return _queues; } 4428 ParallelTaskTerminator* terminator() { return _terminator; } 4429 4430 public: 4431 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4432 G1ParScanThreadState* par_scan_state, 4433 RefToScanQueueSet* queues, 4434 ParallelTaskTerminator* terminator) 4435 : _g1h(g1h), _par_scan_state(par_scan_state), 4436 _queues(queues), _terminator(terminator) {} 4437 4438 void do_void(); 4439 4440 private: 4441 inline bool offer_termination(); 4442 }; 4443 4444 bool G1ParEvacuateFollowersClosure::offer_termination() { 4445 G1ParScanThreadState* const pss = par_scan_state(); 4446 pss->start_term_time(); 4447 const bool res = terminator()->offer_termination(); 4448 pss->end_term_time(); 4449 return res; 4450 } 4451 4452 void G1ParEvacuateFollowersClosure::do_void() { 4453 StarTask stolen_task; 4454 G1ParScanThreadState* const pss = par_scan_state(); 4455 pss->trim_queue(); 4456 4457 do { 4458 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) { 4459 assert(pss->verify_task(stolen_task), "sanity"); 4460 if (stolen_task.is_narrow()) { 4461 pss->deal_with_reference((narrowOop*) stolen_task); 4462 } else { 4463 pss->deal_with_reference((oop*) stolen_task); 4464 } 4465 4466 // We've just processed a reference and we might have made 4467 // available new entries on the queues. So we have to make sure 4468 // we drain the queues as necessary. 4469 pss->trim_queue(); 4470 } 4471 } while (!offer_termination()); 4472 4473 pss->retire_alloc_buffers(); 4474 } 4475 4476 class G1ParTask : public AbstractGangTask { 4477 protected: 4478 G1CollectedHeap* _g1h; 4479 RefToScanQueueSet *_queues; 4480 ParallelTaskTerminator _terminator; 4481 int _n_workers; 4482 4483 Mutex _stats_lock; 4484 Mutex* stats_lock() { return &_stats_lock; } 4485 4486 size_t getNCards() { 4487 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1) 4488 / G1BlockOffsetSharedArray::N_bytes; 4489 } 4490 4491 public: 4492 G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues) 4493 : AbstractGangTask("G1 collection"), 4494 _g1h(g1h), 4495 _queues(task_queues), 4496 _terminator(workers, _queues), 4497 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true), 4498 _n_workers(workers) 4499 {} 4500 4501 RefToScanQueueSet* queues() { return _queues; } 4502 4503 RefToScanQueue *work_queue(int i) { 4504 return queues()->queue(i); 4505 } 4506 4507 void work(int i) { 4508 if (i >= _n_workers) return; // no work needed this round 4509 4510 double start_time_ms = os::elapsedTime() * 1000.0; 4511 _g1h->g1_policy()->record_gc_worker_start_time(i, start_time_ms); 4512 4513 ResourceMark rm; 4514 HandleMark hm; 4515 4516 G1ParScanThreadState pss(_g1h, i); 4517 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss); 4518 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss); 4519 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss); 4520 4521 pss.set_evac_closure(&scan_evac_cl); 4522 pss.set_evac_failure_closure(&evac_failure_cl); 4523 pss.set_partial_scan_closure(&partial_scan_cl); 4524 4525 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss); 4526 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss); 4527 G1ParScanHeapRSClosure only_scan_heap_rs_cl(_g1h, &pss); 4528 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4529 4530 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss); 4531 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss); 4532 G1ParScanAndMarkHeapRSClosure scan_mark_heap_rs_cl(_g1h, &pss); 4533 4534 OopsInHeapRegionClosure *scan_root_cl; 4535 OopsInHeapRegionClosure *scan_perm_cl; 4536 4537 if (_g1h->g1_policy()->during_initial_mark_pause()) { 4538 scan_root_cl = &scan_mark_root_cl; 4539 scan_perm_cl = &scan_mark_perm_cl; 4540 } else { 4541 scan_root_cl = &only_scan_root_cl; 4542 scan_perm_cl = &only_scan_perm_cl; 4543 } 4544 4545 pss.start_strong_roots(); 4546 _g1h->g1_process_strong_roots(/* not collecting perm */ false, 4547 SharedHeap::SO_AllClasses, 4548 scan_root_cl, 4549 &push_heap_rs_cl, 4550 scan_perm_cl, 4551 i); 4552 pss.end_strong_roots(); 4553 4554 { 4555 double start = os::elapsedTime(); 4556 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4557 evac.do_void(); 4558 double elapsed_ms = (os::elapsedTime()-start)*1000.0; 4559 double term_ms = pss.term_time()*1000.0; 4560 _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms); 4561 _g1h->g1_policy()->record_termination(i, term_ms, pss.term_attempts()); 4562 } 4563 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4564 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4565 4566 // Clean up any par-expanded rem sets. 4567 HeapRegionRemSet::par_cleanup(); 4568 4569 if (ParallelGCVerbose) { 4570 MutexLocker x(stats_lock()); 4571 pss.print_termination_stats(i); 4572 } 4573 4574 assert(pss.refs()->is_empty(), "should be empty"); 4575 double end_time_ms = os::elapsedTime() * 1000.0; 4576 _g1h->g1_policy()->record_gc_worker_end_time(i, end_time_ms); 4577 } 4578 }; 4579 4580 // *** Common G1 Evacuation Stuff 4581 4582 // This method is run in a GC worker. 4583 4584 void 4585 G1CollectedHeap:: 4586 g1_process_strong_roots(bool collecting_perm_gen, 4587 SharedHeap::ScanningOption so, 4588 OopClosure* scan_non_heap_roots, 4589 OopsInHeapRegionClosure* scan_rs, 4590 OopsInGenClosure* scan_perm, 4591 int worker_i) { 4592 // First scan the strong roots, including the perm gen. 4593 double ext_roots_start = os::elapsedTime(); 4594 double closure_app_time_sec = 0.0; 4595 4596 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots); 4597 BufferingOopsInGenClosure buf_scan_perm(scan_perm); 4598 buf_scan_perm.set_generation(perm_gen()); 4599 4600 // Walk the code cache w/o buffering, because StarTask cannot handle 4601 // unaligned oop locations. 4602 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, /*do_marking=*/ true); 4603 4604 process_strong_roots(false, // no scoping; this is parallel code 4605 collecting_perm_gen, so, 4606 &buf_scan_non_heap_roots, 4607 &eager_scan_code_roots, 4608 &buf_scan_perm); 4609 4610 // Now the ref_processor roots. 4611 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) { 4612 // We need to treat the discovered reference lists as roots and 4613 // keep entries (which are added by the marking threads) on them 4614 // live until they can be processed at the end of marking. 4615 ref_processor()->weak_oops_do(&buf_scan_non_heap_roots); 4616 } 4617 4618 // Finish up any enqueued closure apps (attributed as object copy time). 4619 buf_scan_non_heap_roots.done(); 4620 buf_scan_perm.done(); 4621 4622 double ext_roots_end = os::elapsedTime(); 4623 4624 g1_policy()->reset_obj_copy_time(worker_i); 4625 double obj_copy_time_sec = buf_scan_perm.closure_app_seconds() + 4626 buf_scan_non_heap_roots.closure_app_seconds(); 4627 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0); 4628 4629 double ext_root_time_ms = 4630 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0; 4631 4632 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms); 4633 4634 // Scan strong roots in mark stack. 4635 if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) { 4636 concurrent_mark()->oops_do(scan_non_heap_roots); 4637 } 4638 double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0; 4639 g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms); 4640 4641 // Now scan the complement of the collection set. 4642 if (scan_rs != NULL) { 4643 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i); 4644 } 4645 4646 _process_strong_tasks->all_tasks_completed(); 4647 } 4648 4649 void 4650 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure, 4651 OopClosure* non_root_closure) { 4652 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false); 4653 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure); 4654 } 4655 4656 void G1CollectedHeap::evacuate_collection_set() { 4657 set_evacuation_failed(false); 4658 4659 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 4660 concurrent_g1_refine()->set_use_cache(false); 4661 concurrent_g1_refine()->clear_hot_cache_claimed_index(); 4662 4663 int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1); 4664 set_par_threads(n_workers); 4665 G1ParTask g1_par_task(this, n_workers, _task_queues); 4666 4667 init_for_evac_failure(NULL); 4668 4669 rem_set()->prepare_for_younger_refs_iterate(true); 4670 4671 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 4672 double start_par = os::elapsedTime(); 4673 if (G1CollectedHeap::use_parallel_gc_threads()) { 4674 // The individual threads will set their evac-failure closures. 4675 StrongRootsScope srs(this); 4676 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr(); 4677 workers()->run_task(&g1_par_task); 4678 } else { 4679 StrongRootsScope srs(this); 4680 g1_par_task.work(0); 4681 } 4682 4683 double par_time = (os::elapsedTime() - start_par) * 1000.0; 4684 g1_policy()->record_par_time(par_time); 4685 set_par_threads(0); 4686 4687 // Weak root processing. 4688 // Note: when JSR 292 is enabled and code blobs can contain 4689 // non-perm oops then we will need to process the code blobs 4690 // here too. 4691 { 4692 G1IsAliveClosure is_alive(this); 4693 G1KeepAliveClosure keep_alive(this); 4694 JNIHandles::weak_oops_do(&is_alive, &keep_alive); 4695 } 4696 release_gc_alloc_regions(); 4697 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 4698 4699 concurrent_g1_refine()->clear_hot_cache(); 4700 concurrent_g1_refine()->set_use_cache(true); 4701 4702 finalize_for_evac_failure(); 4703 4704 // Must do this before removing self-forwarding pointers, which clears 4705 // the per-region evac-failure flags. 4706 concurrent_mark()->complete_marking_in_collection_set(); 4707 4708 if (evacuation_failed()) { 4709 remove_self_forwarding_pointers(); 4710 if (PrintGCDetails) { 4711 gclog_or_tty->print(" (to-space overflow)"); 4712 } else if (PrintGC) { 4713 gclog_or_tty->print("--"); 4714 } 4715 } 4716 4717 if (G1DeferredRSUpdate) { 4718 RedirtyLoggedCardTableEntryFastClosure redirty; 4719 dirty_card_queue_set().set_closure(&redirty); 4720 dirty_card_queue_set().apply_closure_to_all_completed_buffers(); 4721 4722 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 4723 dcq.merge_bufferlists(&dirty_card_queue_set()); 4724 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 4725 } 4726 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 4727 } 4728 4729 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr, 4730 size_t* pre_used, 4731 FreeRegionList* free_list, 4732 HumongousRegionSet* humongous_proxy_set, 4733 HRRSCleanupTask* hrrs_cleanup_task, 4734 bool par) { 4735 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) { 4736 if (hr->isHumongous()) { 4737 assert(hr->startsHumongous(), "we should only see starts humongous"); 4738 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par); 4739 } else { 4740 free_region(hr, pre_used, free_list, par); 4741 } 4742 } else { 4743 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task); 4744 } 4745 } 4746 4747 void G1CollectedHeap::free_region(HeapRegion* hr, 4748 size_t* pre_used, 4749 FreeRegionList* free_list, 4750 bool par) { 4751 assert(!hr->isHumongous(), "this is only for non-humongous regions"); 4752 assert(!hr->is_empty(), "the region should not be empty"); 4753 assert(free_list != NULL, "pre-condition"); 4754 4755 *pre_used += hr->used(); 4756 hr->hr_clear(par, true /* clear_space */); 4757 free_list->add_as_head(hr); 4758 } 4759 4760 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4761 size_t* pre_used, 4762 FreeRegionList* free_list, 4763 HumongousRegionSet* humongous_proxy_set, 4764 bool par) { 4765 assert(hr->startsHumongous(), "this is only for starts humongous regions"); 4766 assert(free_list != NULL, "pre-condition"); 4767 assert(humongous_proxy_set != NULL, "pre-condition"); 4768 4769 size_t hr_used = hr->used(); 4770 size_t hr_capacity = hr->capacity(); 4771 size_t hr_pre_used = 0; 4772 _humongous_set.remove_with_proxy(hr, humongous_proxy_set); 4773 hr->set_notHumongous(); 4774 free_region(hr, &hr_pre_used, free_list, par); 4775 4776 size_t i = hr->hrs_index() + 1; 4777 size_t num = 1; 4778 while (i < n_regions()) { 4779 HeapRegion* curr_hr = region_at(i); 4780 if (!curr_hr->continuesHumongous()) { 4781 break; 4782 } 4783 curr_hr->set_notHumongous(); 4784 free_region(curr_hr, &hr_pre_used, free_list, par); 4785 num += 1; 4786 i += 1; 4787 } 4788 assert(hr_pre_used == hr_used, 4789 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" " 4790 "should be the same", hr_pre_used, hr_used)); 4791 *pre_used += hr_pre_used; 4792 } 4793 4794 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used, 4795 FreeRegionList* free_list, 4796 HumongousRegionSet* humongous_proxy_set, 4797 bool par) { 4798 if (pre_used > 0) { 4799 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL; 4800 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag); 4801 assert(_summary_bytes_used >= pre_used, 4802 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" " 4803 "should be >= pre_used: "SIZE_FORMAT, 4804 _summary_bytes_used, pre_used)); 4805 _summary_bytes_used -= pre_used; 4806 } 4807 if (free_list != NULL && !free_list->is_empty()) { 4808 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4809 _free_list.add_as_head(free_list); 4810 } 4811 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) { 4812 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4813 _humongous_set.update_from_proxy(humongous_proxy_set); 4814 } 4815 } 4816 4817 class G1ParCleanupCTTask : public AbstractGangTask { 4818 CardTableModRefBS* _ct_bs; 4819 G1CollectedHeap* _g1h; 4820 HeapRegion* volatile _su_head; 4821 public: 4822 G1ParCleanupCTTask(CardTableModRefBS* ct_bs, 4823 G1CollectedHeap* g1h) : 4824 AbstractGangTask("G1 Par Cleanup CT Task"), 4825 _ct_bs(ct_bs), _g1h(g1h) { } 4826 4827 void work(int i) { 4828 HeapRegion* r; 4829 while (r = _g1h->pop_dirty_cards_region()) { 4830 clear_cards(r); 4831 } 4832 } 4833 4834 void clear_cards(HeapRegion* r) { 4835 // Cards of the survivors should have already been dirtied. 4836 if (!r->is_survivor()) { 4837 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 4838 } 4839 } 4840 }; 4841 4842 #ifndef PRODUCT 4843 class G1VerifyCardTableCleanup: public HeapRegionClosure { 4844 G1CollectedHeap* _g1h; 4845 CardTableModRefBS* _ct_bs; 4846 public: 4847 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs) 4848 : _g1h(g1h), _ct_bs(ct_bs) { } 4849 virtual bool doHeapRegion(HeapRegion* r) { 4850 if (r->is_survivor()) { 4851 _g1h->verify_dirty_region(r); 4852 } else { 4853 _g1h->verify_not_dirty_region(r); 4854 } 4855 return false; 4856 } 4857 }; 4858 4859 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 4860 // All of the region should be clean. 4861 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set(); 4862 MemRegion mr(hr->bottom(), hr->end()); 4863 ct_bs->verify_not_dirty_region(mr); 4864 } 4865 4866 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 4867 // We cannot guarantee that [bottom(),end()] is dirty. Threads 4868 // dirty allocated blocks as they allocate them. The thread that 4869 // retires each region and replaces it with a new one will do a 4870 // maximal allocation to fill in [pre_dummy_top(),end()] but will 4871 // not dirty that area (one less thing to have to do while holding 4872 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 4873 // is dirty. 4874 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set(); 4875 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 4876 ct_bs->verify_dirty_region(mr); 4877 } 4878 4879 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 4880 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set(); 4881 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 4882 verify_dirty_region(hr); 4883 } 4884 } 4885 4886 void G1CollectedHeap::verify_dirty_young_regions() { 4887 verify_dirty_young_list(_young_list->first_region()); 4888 verify_dirty_young_list(_young_list->first_survivor_region()); 4889 } 4890 #endif 4891 4892 void G1CollectedHeap::cleanUpCardTable() { 4893 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set()); 4894 double start = os::elapsedTime(); 4895 4896 // Iterate over the dirty cards region list. 4897 G1ParCleanupCTTask cleanup_task(ct_bs, this); 4898 4899 if (ParallelGCThreads > 0) { 4900 set_par_threads(workers()->total_workers()); 4901 workers()->run_task(&cleanup_task); 4902 set_par_threads(0); 4903 } else { 4904 while (_dirty_cards_region_list) { 4905 HeapRegion* r = _dirty_cards_region_list; 4906 cleanup_task.clear_cards(r); 4907 _dirty_cards_region_list = r->get_next_dirty_cards_region(); 4908 if (_dirty_cards_region_list == r) { 4909 // The last region. 4910 _dirty_cards_region_list = NULL; 4911 } 4912 r->set_next_dirty_cards_region(NULL); 4913 } 4914 } 4915 4916 double elapsed = os::elapsedTime() - start; 4917 g1_policy()->record_clear_ct_time( elapsed * 1000.0); 4918 #ifndef PRODUCT 4919 if (G1VerifyCTCleanup || VerifyAfterGC) { 4920 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 4921 heap_region_iterate(&cleanup_verifier); 4922 } 4923 #endif 4924 } 4925 4926 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) { 4927 size_t pre_used = 0; 4928 FreeRegionList local_free_list("Local List for CSet Freeing"); 4929 4930 double young_time_ms = 0.0; 4931 double non_young_time_ms = 0.0; 4932 4933 // Since the collection set is a superset of the the young list, 4934 // all we need to do to clear the young list is clear its 4935 // head and length, and unlink any young regions in the code below 4936 _young_list->clear(); 4937 4938 G1CollectorPolicy* policy = g1_policy(); 4939 4940 double start_sec = os::elapsedTime(); 4941 bool non_young = true; 4942 4943 HeapRegion* cur = cs_head; 4944 int age_bound = -1; 4945 size_t rs_lengths = 0; 4946 4947 while (cur != NULL) { 4948 assert(!is_on_master_free_list(cur), "sanity"); 4949 4950 if (non_young) { 4951 if (cur->is_young()) { 4952 double end_sec = os::elapsedTime(); 4953 double elapsed_ms = (end_sec - start_sec) * 1000.0; 4954 non_young_time_ms += elapsed_ms; 4955 4956 start_sec = os::elapsedTime(); 4957 non_young = false; 4958 } 4959 } else { 4960 double end_sec = os::elapsedTime(); 4961 double elapsed_ms = (end_sec - start_sec) * 1000.0; 4962 young_time_ms += elapsed_ms; 4963 4964 start_sec = os::elapsedTime(); 4965 non_young = true; 4966 } 4967 4968 rs_lengths += cur->rem_set()->occupied(); 4969 4970 HeapRegion* next = cur->next_in_collection_set(); 4971 assert(cur->in_collection_set(), "bad CS"); 4972 cur->set_next_in_collection_set(NULL); 4973 cur->set_in_collection_set(false); 4974 4975 if (cur->is_young()) { 4976 int index = cur->young_index_in_cset(); 4977 guarantee( index != -1, "invariant" ); 4978 guarantee( (size_t)index < policy->young_cset_length(), "invariant" ); 4979 size_t words_survived = _surviving_young_words[index]; 4980 cur->record_surv_words_in_group(words_survived); 4981 4982 // At this point the we have 'popped' cur from the collection set 4983 // (linked via next_in_collection_set()) but it is still in the 4984 // young list (linked via next_young_region()). Clear the 4985 // _next_young_region field. 4986 cur->set_next_young_region(NULL); 4987 } else { 4988 int index = cur->young_index_in_cset(); 4989 guarantee( index == -1, "invariant" ); 4990 } 4991 4992 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 4993 (!cur->is_young() && cur->young_index_in_cset() == -1), 4994 "invariant" ); 4995 4996 if (!cur->evacuation_failed()) { 4997 // And the region is empty. 4998 assert(!cur->is_empty(), "Should not have empty regions in a CS."); 4999 free_region(cur, &pre_used, &local_free_list, false /* par */); 5000 } else { 5001 cur->uninstall_surv_rate_group(); 5002 if (cur->is_young()) 5003 cur->set_young_index_in_cset(-1); 5004 cur->set_not_young(); 5005 cur->set_evacuation_failed(false); 5006 } 5007 cur = next; 5008 } 5009 5010 policy->record_max_rs_lengths(rs_lengths); 5011 policy->cset_regions_freed(); 5012 5013 double end_sec = os::elapsedTime(); 5014 double elapsed_ms = (end_sec - start_sec) * 1000.0; 5015 if (non_young) 5016 non_young_time_ms += elapsed_ms; 5017 else 5018 young_time_ms += elapsed_ms; 5019 5020 update_sets_after_freeing_regions(pre_used, &local_free_list, 5021 NULL /* humongous_proxy_set */, 5022 false /* par */); 5023 policy->record_young_free_cset_time_ms(young_time_ms); 5024 policy->record_non_young_free_cset_time_ms(non_young_time_ms); 5025 } 5026 5027 // This routine is similar to the above but does not record 5028 // any policy statistics or update free lists; we are abandoning 5029 // the current incremental collection set in preparation of a 5030 // full collection. After the full GC we will start to build up 5031 // the incremental collection set again. 5032 // This is only called when we're doing a full collection 5033 // and is immediately followed by the tearing down of the young list. 5034 5035 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 5036 HeapRegion* cur = cs_head; 5037 5038 while (cur != NULL) { 5039 HeapRegion* next = cur->next_in_collection_set(); 5040 assert(cur->in_collection_set(), "bad CS"); 5041 cur->set_next_in_collection_set(NULL); 5042 cur->set_in_collection_set(false); 5043 cur->set_young_index_in_cset(-1); 5044 cur = next; 5045 } 5046 } 5047 5048 void G1CollectedHeap::set_free_regions_coming() { 5049 if (G1ConcRegionFreeingVerbose) { 5050 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 5051 "setting free regions coming"); 5052 } 5053 5054 assert(!free_regions_coming(), "pre-condition"); 5055 _free_regions_coming = true; 5056 } 5057 5058 void G1CollectedHeap::reset_free_regions_coming() { 5059 { 5060 assert(free_regions_coming(), "pre-condition"); 5061 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5062 _free_regions_coming = false; 5063 SecondaryFreeList_lock->notify_all(); 5064 } 5065 5066 if (G1ConcRegionFreeingVerbose) { 5067 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 5068 "reset free regions coming"); 5069 } 5070 } 5071 5072 void G1CollectedHeap::wait_while_free_regions_coming() { 5073 // Most of the time we won't have to wait, so let's do a quick test 5074 // first before we take the lock. 5075 if (!free_regions_coming()) { 5076 return; 5077 } 5078 5079 if (G1ConcRegionFreeingVerbose) { 5080 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 5081 "waiting for free regions"); 5082 } 5083 5084 { 5085 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5086 while (free_regions_coming()) { 5087 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 5088 } 5089 } 5090 5091 if (G1ConcRegionFreeingVerbose) { 5092 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 5093 "done waiting for free regions"); 5094 } 5095 } 5096 5097 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 5098 assert(heap_lock_held_for_gc(), 5099 "the heap lock should already be held by or for this thread"); 5100 _young_list->push_region(hr); 5101 g1_policy()->set_region_short_lived(hr); 5102 } 5103 5104 class NoYoungRegionsClosure: public HeapRegionClosure { 5105 private: 5106 bool _success; 5107 public: 5108 NoYoungRegionsClosure() : _success(true) { } 5109 bool doHeapRegion(HeapRegion* r) { 5110 if (r->is_young()) { 5111 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 5112 r->bottom(), r->end()); 5113 _success = false; 5114 } 5115 return false; 5116 } 5117 bool success() { return _success; } 5118 }; 5119 5120 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 5121 bool ret = _young_list->check_list_empty(check_sample); 5122 5123 if (check_heap) { 5124 NoYoungRegionsClosure closure; 5125 heap_region_iterate(&closure); 5126 ret = ret && closure.success(); 5127 } 5128 5129 return ret; 5130 } 5131 5132 void G1CollectedHeap::empty_young_list() { 5133 assert(heap_lock_held_for_gc(), 5134 "the heap lock should already be held by or for this thread"); 5135 5136 _young_list->empty_list(); 5137 } 5138 5139 // Done at the start of full GC. 5140 void G1CollectedHeap::tear_down_region_lists() { 5141 _free_list.remove_all(); 5142 } 5143 5144 class RegionResetter: public HeapRegionClosure { 5145 G1CollectedHeap* _g1h; 5146 FreeRegionList _local_free_list; 5147 5148 public: 5149 RegionResetter() : _g1h(G1CollectedHeap::heap()), 5150 _local_free_list("Local Free List for RegionResetter") { } 5151 5152 bool doHeapRegion(HeapRegion* r) { 5153 if (r->continuesHumongous()) return false; 5154 if (r->top() > r->bottom()) { 5155 if (r->top() < r->end()) { 5156 Copy::fill_to_words(r->top(), 5157 pointer_delta(r->end(), r->top())); 5158 } 5159 } else { 5160 assert(r->is_empty(), "tautology"); 5161 _local_free_list.add_as_tail(r); 5162 } 5163 return false; 5164 } 5165 5166 void update_free_lists() { 5167 _g1h->update_sets_after_freeing_regions(0, &_local_free_list, NULL, 5168 false /* par */); 5169 } 5170 }; 5171 5172 // Done at the end of full GC. 5173 void G1CollectedHeap::rebuild_region_lists() { 5174 // This needs to go at the end of the full GC. 5175 RegionResetter rs; 5176 heap_region_iterate(&rs); 5177 rs.update_free_lists(); 5178 } 5179 5180 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 5181 _refine_cte_cl->set_concurrent(concurrent); 5182 } 5183 5184 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 5185 HeapRegion* hr = heap_region_containing(p); 5186 if (hr == NULL) { 5187 return is_in_permanent(p); 5188 } else { 5189 return hr->is_in(p); 5190 } 5191 } 5192 5193 // Methods for the mutator alloc region 5194 5195 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 5196 bool force) { 5197 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 5198 assert(!force || g1_policy()->can_expand_young_list(), 5199 "if force is true we should be able to expand the young list"); 5200 bool young_list_full = g1_policy()->is_young_list_full(); 5201 if (force || !young_list_full) { 5202 HeapRegion* new_alloc_region = new_region(word_size, 5203 false /* do_expand */); 5204 if (new_alloc_region != NULL) { 5205 g1_policy()->update_region_num(true /* next_is_young */); 5206 set_region_short_lived_locked(new_alloc_region); 5207 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 5208 g1mm()->update_eden_counters(); 5209 return new_alloc_region; 5210 } 5211 } 5212 return NULL; 5213 } 5214 5215 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 5216 size_t allocated_bytes) { 5217 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 5218 assert(alloc_region->is_young(), "all mutator alloc regions should be young"); 5219 5220 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 5221 _summary_bytes_used += allocated_bytes; 5222 _hr_printer.retire(alloc_region); 5223 } 5224 5225 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size, 5226 bool force) { 5227 return _g1h->new_mutator_alloc_region(word_size, force); 5228 } 5229 5230 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region, 5231 size_t allocated_bytes) { 5232 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes); 5233 } 5234 5235 // Methods for the GC alloc regions 5236 5237 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 5238 size_t count, 5239 GCAllocPurpose ap) { 5240 assert(FreeList_lock->owned_by_self(), "pre-condition"); 5241 5242 if (count < g1_policy()->max_regions(ap)) { 5243 HeapRegion* new_alloc_region = new_region(word_size, 5244 true /* do_expand */); 5245 if (new_alloc_region != NULL) { 5246 // We really only need to do this for old regions given that we 5247 // should never scan survivors. But it doesn't hurt to do it 5248 // for survivors too. 5249 new_alloc_region->set_saved_mark(); 5250 if (ap == GCAllocForSurvived) { 5251 new_alloc_region->set_survivor(); 5252 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 5253 } else { 5254 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 5255 } 5256 return new_alloc_region; 5257 } else { 5258 g1_policy()->note_alloc_region_limit_reached(ap); 5259 } 5260 } 5261 return NULL; 5262 } 5263 5264 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 5265 size_t allocated_bytes, 5266 GCAllocPurpose ap) { 5267 alloc_region->note_end_of_copying(); 5268 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 5269 if (ap == GCAllocForSurvived) { 5270 young_list()->add_survivor_region(alloc_region); 5271 } 5272 _hr_printer.retire(alloc_region); 5273 } 5274 5275 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size, 5276 bool force) { 5277 assert(!force, "not supported for GC alloc regions"); 5278 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived); 5279 } 5280 5281 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region, 5282 size_t allocated_bytes) { 5283 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 5284 GCAllocForSurvived); 5285 } 5286 5287 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size, 5288 bool force) { 5289 assert(!force, "not supported for GC alloc regions"); 5290 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured); 5291 } 5292 5293 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region, 5294 size_t allocated_bytes) { 5295 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 5296 GCAllocForTenured); 5297 } 5298 // Heap region set verification 5299 5300 class VerifyRegionListsClosure : public HeapRegionClosure { 5301 private: 5302 HumongousRegionSet* _humongous_set; 5303 FreeRegionList* _free_list; 5304 size_t _region_count; 5305 5306 public: 5307 VerifyRegionListsClosure(HumongousRegionSet* humongous_set, 5308 FreeRegionList* free_list) : 5309 _humongous_set(humongous_set), _free_list(free_list), 5310 _region_count(0) { } 5311 5312 size_t region_count() { return _region_count; } 5313 5314 bool doHeapRegion(HeapRegion* hr) { 5315 _region_count += 1; 5316 5317 if (hr->continuesHumongous()) { 5318 return false; 5319 } 5320 5321 if (hr->is_young()) { 5322 // TODO 5323 } else if (hr->startsHumongous()) { 5324 _humongous_set->verify_next_region(hr); 5325 } else if (hr->is_empty()) { 5326 _free_list->verify_next_region(hr); 5327 } 5328 return false; 5329 } 5330 }; 5331 5332 HeapRegion* G1CollectedHeap::new_heap_region(size_t hrs_index, 5333 HeapWord* bottom) { 5334 HeapWord* end = bottom + HeapRegion::GrainWords; 5335 MemRegion mr(bottom, end); 5336 assert(_g1_reserved.contains(mr), "invariant"); 5337 // This might return NULL if the allocation fails 5338 return new HeapRegion(hrs_index, _bot_shared, mr, true /* is_zeroed */); 5339 } 5340 5341 void G1CollectedHeap::verify_region_sets() { 5342 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 5343 5344 // First, check the explicit lists. 5345 _free_list.verify(); 5346 { 5347 // Given that a concurrent operation might be adding regions to 5348 // the secondary free list we have to take the lock before 5349 // verifying it. 5350 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 5351 _secondary_free_list.verify(); 5352 } 5353 _humongous_set.verify(); 5354 5355 // If a concurrent region freeing operation is in progress it will 5356 // be difficult to correctly attributed any free regions we come 5357 // across to the correct free list given that they might belong to 5358 // one of several (free_list, secondary_free_list, any local lists, 5359 // etc.). So, if that's the case we will skip the rest of the 5360 // verification operation. Alternatively, waiting for the concurrent 5361 // operation to complete will have a non-trivial effect on the GC's 5362 // operation (no concurrent operation will last longer than the 5363 // interval between two calls to verification) and it might hide 5364 // any issues that we would like to catch during testing. 5365 if (free_regions_coming()) { 5366 return; 5367 } 5368 5369 // Make sure we append the secondary_free_list on the free_list so 5370 // that all free regions we will come across can be safely 5371 // attributed to the free_list. 5372 append_secondary_free_list_if_not_empty_with_lock(); 5373 5374 // Finally, make sure that the region accounting in the lists is 5375 // consistent with what we see in the heap. 5376 _humongous_set.verify_start(); 5377 _free_list.verify_start(); 5378 5379 VerifyRegionListsClosure cl(&_humongous_set, &_free_list); 5380 heap_region_iterate(&cl); 5381 5382 _humongous_set.verify_end(); 5383 _free_list.verify_end(); 5384 }