1 /* 2 * Copyright (c) 2001, 2012, 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/g1ErgoVerbose.hpp" 35 #include "gc_implementation/g1/g1EvacFailure.hpp" 36 #include "gc_implementation/g1/g1GCPhaseTimes.hpp" 37 #include "gc_implementation/g1/g1Log.hpp" 38 #include "gc_implementation/g1/g1MarkSweep.hpp" 39 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 40 #include "gc_implementation/g1/g1RemSet.inline.hpp" 41 #include "gc_implementation/g1/g1YCTypes.hpp" 42 #include "gc_implementation/g1/heapRegion.inline.hpp" 43 #include "gc_implementation/g1/heapRegionRemSet.hpp" 44 #include "gc_implementation/g1/heapRegionSeq.inline.hpp" 45 #include "gc_implementation/g1/vm_operations_g1.hpp" 46 #include "gc_implementation/shared/gcHeapSummary.hpp" 47 #include "gc_implementation/shared/gcTimer.hpp" 48 #include "gc_implementation/shared/gcTrace.hpp" 49 #include "gc_implementation/shared/gcTraceTime.hpp" 50 #include "gc_implementation/shared/isGCActiveMark.hpp" 51 #include "memory/gcLocker.inline.hpp" 52 #include "memory/genOopClosures.inline.hpp" 53 #include "memory/generationSpec.hpp" 54 #include "memory/referenceProcessor.hpp" 55 #include "oops/oop.inline.hpp" 56 #include "oops/oop.pcgc.inline.hpp" 57 #include "runtime/aprofiler.hpp" 58 #include "runtime/vmThread.hpp" 59 60 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 61 62 // turn it on so that the contents of the young list (scan-only / 63 // to-be-collected) are printed at "strategic" points before / during 64 // / after the collection --- this is useful for debugging 65 #define YOUNG_LIST_VERBOSE 0 66 // CURRENT STATUS 67 // This file is under construction. Search for "FIXME". 68 69 // INVARIANTS/NOTES 70 // 71 // All allocation activity covered by the G1CollectedHeap interface is 72 // serialized by acquiring the HeapLock. This happens in mem_allocate 73 // and allocate_new_tlab, which are the "entry" points to the 74 // allocation code from the rest of the JVM. (Note that this does not 75 // apply to TLAB allocation, which is not part of this interface: it 76 // is done by clients of this interface.) 77 78 // Notes on implementation of parallelism in different tasks. 79 // 80 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism. 81 // The number of GC workers is passed to heap_region_par_iterate_chunked(). 82 // It does use run_task() which sets _n_workers in the task. 83 // G1ParTask executes g1_process_strong_roots() -> 84 // SharedHeap::process_strong_roots() which calls eventually to 85 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses 86 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also 87 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap). 88 // 89 90 // Local to this file. 91 92 class RefineCardTableEntryClosure: public CardTableEntryClosure { 93 SuspendibleThreadSet* _sts; 94 G1RemSet* _g1rs; 95 ConcurrentG1Refine* _cg1r; 96 bool _concurrent; 97 public: 98 RefineCardTableEntryClosure(SuspendibleThreadSet* sts, 99 G1RemSet* g1rs, 100 ConcurrentG1Refine* cg1r) : 101 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true) 102 {} 103 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 104 bool oops_into_cset = _g1rs->concurrentRefineOneCard(card_ptr, worker_i, false); 105 // This path is executed by the concurrent refine or mutator threads, 106 // concurrently, and so we do not care if card_ptr contains references 107 // that point into the collection set. 108 assert(!oops_into_cset, "should be"); 109 110 if (_concurrent && _sts->should_yield()) { 111 // Caller will actually yield. 112 return false; 113 } 114 // Otherwise, we finished successfully; return true. 115 return true; 116 } 117 void set_concurrent(bool b) { _concurrent = b; } 118 }; 119 120 121 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure { 122 int _calls; 123 G1CollectedHeap* _g1h; 124 CardTableModRefBS* _ctbs; 125 int _histo[256]; 126 public: 127 ClearLoggedCardTableEntryClosure() : 128 _calls(0) 129 { 130 _g1h = G1CollectedHeap::heap(); 131 _ctbs = (CardTableModRefBS*)_g1h->barrier_set(); 132 for (int i = 0; i < 256; i++) _histo[i] = 0; 133 } 134 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 135 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) { 136 _calls++; 137 unsigned char* ujb = (unsigned char*)card_ptr; 138 int ind = (int)(*ujb); 139 _histo[ind]++; 140 *card_ptr = -1; 141 } 142 return true; 143 } 144 int calls() { return _calls; } 145 void print_histo() { 146 gclog_or_tty->print_cr("Card table value histogram:"); 147 for (int i = 0; i < 256; i++) { 148 if (_histo[i] != 0) { 149 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]); 150 } 151 } 152 } 153 }; 154 155 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure { 156 int _calls; 157 G1CollectedHeap* _g1h; 158 CardTableModRefBS* _ctbs; 159 public: 160 RedirtyLoggedCardTableEntryClosure() : 161 _calls(0) 162 { 163 _g1h = G1CollectedHeap::heap(); 164 _ctbs = (CardTableModRefBS*)_g1h->barrier_set(); 165 } 166 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 167 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) { 168 _calls++; 169 *card_ptr = 0; 170 } 171 return true; 172 } 173 int calls() { return _calls; } 174 }; 175 176 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure { 177 public: 178 bool do_card_ptr(jbyte* card_ptr, int worker_i) { 179 *card_ptr = CardTableModRefBS::dirty_card_val(); 180 return true; 181 } 182 }; 183 184 YoungList::YoungList(G1CollectedHeap* g1h) : 185 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 186 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 187 guarantee(check_list_empty(false), "just making sure..."); 188 } 189 190 void YoungList::push_region(HeapRegion *hr) { 191 assert(!hr->is_young(), "should not already be young"); 192 assert(hr->get_next_young_region() == NULL, "cause it should!"); 193 194 hr->set_next_young_region(_head); 195 _head = hr; 196 197 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 198 ++_length; 199 } 200 201 void YoungList::add_survivor_region(HeapRegion* hr) { 202 assert(hr->is_survivor(), "should be flagged as survivor region"); 203 assert(hr->get_next_young_region() == NULL, "cause it should!"); 204 205 hr->set_next_young_region(_survivor_head); 206 if (_survivor_head == NULL) { 207 _survivor_tail = hr; 208 } 209 _survivor_head = hr; 210 ++_survivor_length; 211 } 212 213 void YoungList::empty_list(HeapRegion* list) { 214 while (list != NULL) { 215 HeapRegion* next = list->get_next_young_region(); 216 list->set_next_young_region(NULL); 217 list->uninstall_surv_rate_group(); 218 list->set_not_young(); 219 list = next; 220 } 221 } 222 223 void YoungList::empty_list() { 224 assert(check_list_well_formed(), "young list should be well formed"); 225 226 empty_list(_head); 227 _head = NULL; 228 _length = 0; 229 230 empty_list(_survivor_head); 231 _survivor_head = NULL; 232 _survivor_tail = NULL; 233 _survivor_length = 0; 234 235 _last_sampled_rs_lengths = 0; 236 237 assert(check_list_empty(false), "just making sure..."); 238 } 239 240 bool YoungList::check_list_well_formed() { 241 bool ret = true; 242 243 uint length = 0; 244 HeapRegion* curr = _head; 245 HeapRegion* last = NULL; 246 while (curr != NULL) { 247 if (!curr->is_young()) { 248 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " 249 "incorrectly tagged (y: %d, surv: %d)", 250 curr->bottom(), curr->end(), 251 curr->is_young(), curr->is_survivor()); 252 ret = false; 253 } 254 ++length; 255 last = curr; 256 curr = curr->get_next_young_region(); 257 } 258 ret = ret && (length == _length); 259 260 if (!ret) { 261 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 262 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 263 length, _length); 264 } 265 266 return ret; 267 } 268 269 bool YoungList::check_list_empty(bool check_sample) { 270 bool ret = true; 271 272 if (_length != 0) { 273 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 274 _length); 275 ret = false; 276 } 277 if (check_sample && _last_sampled_rs_lengths != 0) { 278 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 279 ret = false; 280 } 281 if (_head != NULL) { 282 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 283 ret = false; 284 } 285 if (!ret) { 286 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 287 } 288 289 return ret; 290 } 291 292 void 293 YoungList::rs_length_sampling_init() { 294 _sampled_rs_lengths = 0; 295 _curr = _head; 296 } 297 298 bool 299 YoungList::rs_length_sampling_more() { 300 return _curr != NULL; 301 } 302 303 void 304 YoungList::rs_length_sampling_next() { 305 assert( _curr != NULL, "invariant" ); 306 size_t rs_length = _curr->rem_set()->occupied(); 307 308 _sampled_rs_lengths += rs_length; 309 310 // The current region may not yet have been added to the 311 // incremental collection set (it gets added when it is 312 // retired as the current allocation region). 313 if (_curr->in_collection_set()) { 314 // Update the collection set policy information for this region 315 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 316 } 317 318 _curr = _curr->get_next_young_region(); 319 if (_curr == NULL) { 320 _last_sampled_rs_lengths = _sampled_rs_lengths; 321 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 322 } 323 } 324 325 void 326 YoungList::reset_auxilary_lists() { 327 guarantee( is_empty(), "young list should be empty" ); 328 assert(check_list_well_formed(), "young list should be well formed"); 329 330 // Add survivor regions to SurvRateGroup. 331 _g1h->g1_policy()->note_start_adding_survivor_regions(); 332 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 333 334 int young_index_in_cset = 0; 335 for (HeapRegion* curr = _survivor_head; 336 curr != NULL; 337 curr = curr->get_next_young_region()) { 338 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 339 340 // The region is a non-empty survivor so let's add it to 341 // the incremental collection set for the next evacuation 342 // pause. 343 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 344 young_index_in_cset += 1; 345 } 346 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 347 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 348 349 _head = _survivor_head; 350 _length = _survivor_length; 351 if (_survivor_head != NULL) { 352 assert(_survivor_tail != NULL, "cause it shouldn't be"); 353 assert(_survivor_length > 0, "invariant"); 354 _survivor_tail->set_next_young_region(NULL); 355 } 356 357 // Don't clear the survivor list handles until the start of 358 // the next evacuation pause - we need it in order to re-tag 359 // the survivor regions from this evacuation pause as 'young' 360 // at the start of the next. 361 362 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 363 364 assert(check_list_well_formed(), "young list should be well formed"); 365 } 366 367 void YoungList::print() { 368 HeapRegion* lists[] = {_head, _survivor_head}; 369 const char* names[] = {"YOUNG", "SURVIVOR"}; 370 371 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) { 372 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 373 HeapRegion *curr = lists[list]; 374 if (curr == NULL) 375 gclog_or_tty->print_cr(" empty"); 376 while (curr != NULL) { 377 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d", 378 HR_FORMAT_PARAMS(curr), 379 curr->prev_top_at_mark_start(), 380 curr->next_top_at_mark_start(), 381 curr->age_in_surv_rate_group_cond()); 382 curr = curr->get_next_young_region(); 383 } 384 } 385 386 gclog_or_tty->print_cr(""); 387 } 388 389 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 390 { 391 // Claim the right to put the region on the dirty cards region list 392 // by installing a self pointer. 393 HeapRegion* next = hr->get_next_dirty_cards_region(); 394 if (next == NULL) { 395 HeapRegion* res = (HeapRegion*) 396 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 397 NULL); 398 if (res == NULL) { 399 HeapRegion* head; 400 do { 401 // Put the region to the dirty cards region list. 402 head = _dirty_cards_region_list; 403 next = (HeapRegion*) 404 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 405 if (next == head) { 406 assert(hr->get_next_dirty_cards_region() == hr, 407 "hr->get_next_dirty_cards_region() != hr"); 408 if (next == NULL) { 409 // The last region in the list points to itself. 410 hr->set_next_dirty_cards_region(hr); 411 } else { 412 hr->set_next_dirty_cards_region(next); 413 } 414 } 415 } while (next != head); 416 } 417 } 418 } 419 420 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 421 { 422 HeapRegion* head; 423 HeapRegion* hr; 424 do { 425 head = _dirty_cards_region_list; 426 if (head == NULL) { 427 return NULL; 428 } 429 HeapRegion* new_head = head->get_next_dirty_cards_region(); 430 if (head == new_head) { 431 // The last region. 432 new_head = NULL; 433 } 434 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 435 head); 436 } while (hr != head); 437 assert(hr != NULL, "invariant"); 438 hr->set_next_dirty_cards_region(NULL); 439 return hr; 440 } 441 442 void G1CollectedHeap::stop_conc_gc_threads() { 443 _cg1r->stop(); 444 _cmThread->stop(); 445 } 446 447 #ifdef ASSERT 448 // A region is added to the collection set as it is retired 449 // so an address p can point to a region which will be in the 450 // collection set but has not yet been retired. This method 451 // therefore is only accurate during a GC pause after all 452 // regions have been retired. It is used for debugging 453 // to check if an nmethod has references to objects that can 454 // be move during a partial collection. Though it can be 455 // inaccurate, it is sufficient for G1 because the conservative 456 // implementation of is_scavengable() for G1 will indicate that 457 // all nmethods must be scanned during a partial collection. 458 bool G1CollectedHeap::is_in_partial_collection(const void* p) { 459 HeapRegion* hr = heap_region_containing(p); 460 return hr != NULL && hr->in_collection_set(); 461 } 462 #endif 463 464 // Returns true if the reference points to an object that 465 // can move in an incremental collection. 466 bool G1CollectedHeap::is_scavengable(const void* p) { 467 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 468 G1CollectorPolicy* g1p = g1h->g1_policy(); 469 HeapRegion* hr = heap_region_containing(p); 470 if (hr == NULL) { 471 // perm gen (or null) 472 return false; 473 } else { 474 return !hr->isHumongous(); 475 } 476 } 477 478 void G1CollectedHeap::check_ct_logs_at_safepoint() { 479 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 480 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set(); 481 482 // Count the dirty cards at the start. 483 CountNonCleanMemRegionClosure count1(this); 484 ct_bs->mod_card_iterate(&count1); 485 int orig_count = count1.n(); 486 487 // First clear the logged cards. 488 ClearLoggedCardTableEntryClosure clear; 489 dcqs.set_closure(&clear); 490 dcqs.apply_closure_to_all_completed_buffers(); 491 dcqs.iterate_closure_all_threads(false); 492 clear.print_histo(); 493 494 // Now ensure that there's no dirty cards. 495 CountNonCleanMemRegionClosure count2(this); 496 ct_bs->mod_card_iterate(&count2); 497 if (count2.n() != 0) { 498 gclog_or_tty->print_cr("Card table has %d entries; %d originally", 499 count2.n(), orig_count); 500 } 501 guarantee(count2.n() == 0, "Card table should be clean."); 502 503 RedirtyLoggedCardTableEntryClosure redirty; 504 JavaThread::dirty_card_queue_set().set_closure(&redirty); 505 dcqs.apply_closure_to_all_completed_buffers(); 506 dcqs.iterate_closure_all_threads(false); 507 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.", 508 clear.calls(), orig_count); 509 guarantee(redirty.calls() == clear.calls(), 510 "Or else mechanism is broken."); 511 512 CountNonCleanMemRegionClosure count3(this); 513 ct_bs->mod_card_iterate(&count3); 514 if (count3.n() != orig_count) { 515 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.", 516 orig_count, count3.n()); 517 guarantee(count3.n() >= orig_count, "Should have restored them all."); 518 } 519 520 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl); 521 } 522 523 // Private class members. 524 525 G1CollectedHeap* G1CollectedHeap::_g1h; 526 527 // Private methods. 528 529 HeapRegion* 530 G1CollectedHeap::new_region_try_secondary_free_list() { 531 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 532 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 533 if (!_secondary_free_list.is_empty()) { 534 if (G1ConcRegionFreeingVerbose) { 535 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 536 "secondary_free_list has %u entries", 537 _secondary_free_list.length()); 538 } 539 // It looks as if there are free regions available on the 540 // secondary_free_list. Let's move them to the free_list and try 541 // again to allocate from it. 542 append_secondary_free_list(); 543 544 assert(!_free_list.is_empty(), "if the secondary_free_list was not " 545 "empty we should have moved at least one entry to the free_list"); 546 HeapRegion* res = _free_list.remove_head(); 547 if (G1ConcRegionFreeingVerbose) { 548 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 549 "allocated "HR_FORMAT" from secondary_free_list", 550 HR_FORMAT_PARAMS(res)); 551 } 552 return res; 553 } 554 555 // Wait here until we get notified either when (a) there are no 556 // more free regions coming or (b) some regions have been moved on 557 // the secondary_free_list. 558 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 559 } 560 561 if (G1ConcRegionFreeingVerbose) { 562 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 563 "could not allocate from secondary_free_list"); 564 } 565 return NULL; 566 } 567 568 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) { 569 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords, 570 "the only time we use this to allocate a humongous region is " 571 "when we are allocating a single humongous region"); 572 573 HeapRegion* res; 574 if (G1StressConcRegionFreeing) { 575 if (!_secondary_free_list.is_empty()) { 576 if (G1ConcRegionFreeingVerbose) { 577 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 578 "forced to look at the secondary_free_list"); 579 } 580 res = new_region_try_secondary_free_list(); 581 if (res != NULL) { 582 return res; 583 } 584 } 585 } 586 res = _free_list.remove_head_or_null(); 587 if (res == NULL) { 588 if (G1ConcRegionFreeingVerbose) { 589 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 590 "res == NULL, trying the secondary_free_list"); 591 } 592 res = new_region_try_secondary_free_list(); 593 } 594 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 595 // Currently, only attempts to allocate GC alloc regions set 596 // do_expand to true. So, we should only reach here during a 597 // safepoint. If this assumption changes we might have to 598 // reconsider the use of _expand_heap_after_alloc_failure. 599 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 600 601 ergo_verbose1(ErgoHeapSizing, 602 "attempt heap expansion", 603 ergo_format_reason("region allocation request failed") 604 ergo_format_byte("allocation request"), 605 word_size * HeapWordSize); 606 if (expand(word_size * HeapWordSize)) { 607 // Given that expand() succeeded in expanding the heap, and we 608 // always expand the heap by an amount aligned to the heap 609 // region size, the free list should in theory not be empty. So 610 // it would probably be OK to use remove_head(). But the extra 611 // check for NULL is unlikely to be a performance issue here (we 612 // just expanded the heap!) so let's just be conservative and 613 // use remove_head_or_null(). 614 res = _free_list.remove_head_or_null(); 615 } else { 616 _expand_heap_after_alloc_failure = false; 617 } 618 } 619 return res; 620 } 621 622 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions, 623 size_t word_size) { 624 assert(isHumongous(word_size), "word_size should be humongous"); 625 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 626 627 uint first = G1_NULL_HRS_INDEX; 628 if (num_regions == 1) { 629 // Only one region to allocate, no need to go through the slower 630 // path. The caller will attempt the expansion if this fails, so 631 // let's not try to expand here too. 632 HeapRegion* hr = new_region(word_size, false /* do_expand */); 633 if (hr != NULL) { 634 first = hr->hrs_index(); 635 } else { 636 first = G1_NULL_HRS_INDEX; 637 } 638 } else { 639 // We can't allocate humongous regions while cleanupComplete() is 640 // running, since some of the regions we find to be empty might not 641 // yet be added to the free list and it is not straightforward to 642 // know which list they are on so that we can remove them. Note 643 // that we only need to do this if we need to allocate more than 644 // one region to satisfy the current humongous allocation 645 // request. If we are only allocating one region we use the common 646 // region allocation code (see above). 647 wait_while_free_regions_coming(); 648 append_secondary_free_list_if_not_empty_with_lock(); 649 650 if (free_regions() >= num_regions) { 651 first = _hrs.find_contiguous(num_regions); 652 if (first != G1_NULL_HRS_INDEX) { 653 for (uint i = first; i < first + num_regions; ++i) { 654 HeapRegion* hr = region_at(i); 655 assert(hr->is_empty(), "sanity"); 656 assert(is_on_master_free_list(hr), "sanity"); 657 hr->set_pending_removal(true); 658 } 659 _free_list.remove_all_pending(num_regions); 660 } 661 } 662 } 663 return first; 664 } 665 666 HeapWord* 667 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 668 uint num_regions, 669 size_t word_size) { 670 assert(first != G1_NULL_HRS_INDEX, "pre-condition"); 671 assert(isHumongous(word_size), "word_size should be humongous"); 672 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 673 674 // Index of last region in the series + 1. 675 uint last = first + num_regions; 676 677 // We need to initialize the region(s) we just discovered. This is 678 // a bit tricky given that it can happen concurrently with 679 // refinement threads refining cards on these regions and 680 // potentially wanting to refine the BOT as they are scanning 681 // those cards (this can happen shortly after a cleanup; see CR 682 // 6991377). So we have to set up the region(s) carefully and in 683 // a specific order. 684 685 // The word size sum of all the regions we will allocate. 686 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 687 assert(word_size <= word_size_sum, "sanity"); 688 689 // This will be the "starts humongous" region. 690 HeapRegion* first_hr = region_at(first); 691 // The header of the new object will be placed at the bottom of 692 // the first region. 693 HeapWord* new_obj = first_hr->bottom(); 694 // This will be the new end of the first region in the series that 695 // should also match the end of the last region in the series. 696 HeapWord* new_end = new_obj + word_size_sum; 697 // This will be the new top of the first region that will reflect 698 // this allocation. 699 HeapWord* new_top = new_obj + word_size; 700 701 // First, we need to zero the header of the space that we will be 702 // allocating. When we update top further down, some refinement 703 // threads might try to scan the region. By zeroing the header we 704 // ensure that any thread that will try to scan the region will 705 // come across the zero klass word and bail out. 706 // 707 // NOTE: It would not have been correct to have used 708 // CollectedHeap::fill_with_object() and make the space look like 709 // an int array. The thread that is doing the allocation will 710 // later update the object header to a potentially different array 711 // type and, for a very short period of time, the klass and length 712 // fields will be inconsistent. This could cause a refinement 713 // thread to calculate the object size incorrectly. 714 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 715 716 // We will set up the first region as "starts humongous". This 717 // will also update the BOT covering all the regions to reflect 718 // that there is a single object that starts at the bottom of the 719 // first region. 720 first_hr->set_startsHumongous(new_top, new_end); 721 722 // Then, if there are any, we will set up the "continues 723 // humongous" regions. 724 HeapRegion* hr = NULL; 725 for (uint i = first + 1; i < last; ++i) { 726 hr = region_at(i); 727 hr->set_continuesHumongous(first_hr); 728 } 729 // If we have "continues humongous" regions (hr != NULL), then the 730 // end of the last one should match new_end. 731 assert(hr == NULL || hr->end() == new_end, "sanity"); 732 733 // Up to this point no concurrent thread would have been able to 734 // do any scanning on any region in this series. All the top 735 // fields still point to bottom, so the intersection between 736 // [bottom,top] and [card_start,card_end] will be empty. Before we 737 // update the top fields, we'll do a storestore to make sure that 738 // no thread sees the update to top before the zeroing of the 739 // object header and the BOT initialization. 740 OrderAccess::storestore(); 741 742 // Now that the BOT and the object header have been initialized, 743 // we can update top of the "starts humongous" region. 744 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 745 "new_top should be in this region"); 746 first_hr->set_top(new_top); 747 if (_hr_printer.is_active()) { 748 HeapWord* bottom = first_hr->bottom(); 749 HeapWord* end = first_hr->orig_end(); 750 if ((first + 1) == last) { 751 // the series has a single humongous region 752 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 753 } else { 754 // the series has more than one humongous regions 755 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 756 } 757 } 758 759 // Now, we will update the top fields of the "continues humongous" 760 // regions. The reason we need to do this is that, otherwise, 761 // these regions would look empty and this will confuse parts of 762 // G1. For example, the code that looks for a consecutive number 763 // of empty regions will consider them empty and try to 764 // re-allocate them. We can extend is_empty() to also include 765 // !continuesHumongous(), but it is easier to just update the top 766 // fields here. The way we set top for all regions (i.e., top == 767 // end for all regions but the last one, top == new_top for the 768 // last one) is actually used when we will free up the humongous 769 // region in free_humongous_region(). 770 hr = NULL; 771 for (uint i = first + 1; i < last; ++i) { 772 hr = region_at(i); 773 if ((i + 1) == last) { 774 // last continues humongous region 775 assert(hr->bottom() < new_top && new_top <= hr->end(), 776 "new_top should fall on this region"); 777 hr->set_top(new_top); 778 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 779 } else { 780 // not last one 781 assert(new_top > hr->end(), "new_top should be above this region"); 782 hr->set_top(hr->end()); 783 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 784 } 785 } 786 // If we have continues humongous regions (hr != NULL), then the 787 // end of the last one should match new_end and its top should 788 // match new_top. 789 assert(hr == NULL || 790 (hr->end() == new_end && hr->top() == new_top), "sanity"); 791 792 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 793 _summary_bytes_used += first_hr->used(); 794 _humongous_set.add(first_hr); 795 796 return new_obj; 797 } 798 799 // If could fit into free regions w/o expansion, try. 800 // Otherwise, if can expand, do so. 801 // Otherwise, if using ex regions might help, try with ex given back. 802 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 803 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 804 805 verify_region_sets_optional(); 806 807 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords); 808 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords); 809 uint x_num = expansion_regions(); 810 uint fs = _hrs.free_suffix(); 811 uint first = humongous_obj_allocate_find_first(num_regions, word_size); 812 if (first == G1_NULL_HRS_INDEX) { 813 // The only thing we can do now is attempt expansion. 814 if (fs + x_num >= num_regions) { 815 // If the number of regions we're trying to allocate for this 816 // object is at most the number of regions in the free suffix, 817 // then the call to humongous_obj_allocate_find_first() above 818 // should have succeeded and we wouldn't be here. 819 // 820 // We should only be trying to expand when the free suffix is 821 // not sufficient for the object _and_ we have some expansion 822 // room available. 823 assert(num_regions > fs, "earlier allocation should have succeeded"); 824 825 ergo_verbose1(ErgoHeapSizing, 826 "attempt heap expansion", 827 ergo_format_reason("humongous allocation request failed") 828 ergo_format_byte("allocation request"), 829 word_size * HeapWordSize); 830 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) { 831 // Even though the heap was expanded, it might not have 832 // reached the desired size. So, we cannot assume that the 833 // allocation will succeed. 834 first = humongous_obj_allocate_find_first(num_regions, word_size); 835 } 836 } 837 } 838 839 HeapWord* result = NULL; 840 if (first != G1_NULL_HRS_INDEX) { 841 result = 842 humongous_obj_allocate_initialize_regions(first, num_regions, word_size); 843 assert(result != NULL, "it should always return a valid result"); 844 845 // A successful humongous object allocation changes the used space 846 // information of the old generation so we need to recalculate the 847 // sizes and update the jstat counters here. 848 g1mm()->update_sizes(); 849 } 850 851 verify_region_sets_optional(); 852 853 return result; 854 } 855 856 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 857 assert_heap_not_locked_and_not_at_safepoint(); 858 assert(!isHumongous(word_size), "we do not allow humongous TLABs"); 859 860 unsigned int dummy_gc_count_before; 861 return attempt_allocation(word_size, &dummy_gc_count_before); 862 } 863 864 HeapWord* 865 G1CollectedHeap::mem_allocate(size_t word_size, 866 bool* gc_overhead_limit_was_exceeded) { 867 assert_heap_not_locked_and_not_at_safepoint(); 868 869 // Loop until the allocation is satisfied, or unsatisfied after GC. 870 for (int try_count = 1; /* we'll return */; try_count += 1) { 871 unsigned int gc_count_before; 872 873 HeapWord* result = NULL; 874 if (!isHumongous(word_size)) { 875 result = attempt_allocation(word_size, &gc_count_before); 876 } else { 877 result = attempt_allocation_humongous(word_size, &gc_count_before); 878 } 879 if (result != NULL) { 880 return result; 881 } 882 883 // Create the garbage collection operation... 884 VM_G1CollectForAllocation op(gc_count_before, word_size); 885 // ...and get the VM thread to execute it. 886 VMThread::execute(&op); 887 888 if (op.prologue_succeeded() && op.pause_succeeded()) { 889 // If the operation was successful we'll return the result even 890 // if it is NULL. If the allocation attempt failed immediately 891 // after a Full GC, it's unlikely we'll be able to allocate now. 892 HeapWord* result = op.result(); 893 if (result != NULL && !isHumongous(word_size)) { 894 // Allocations that take place on VM operations do not do any 895 // card dirtying and we have to do it here. We only have to do 896 // this for non-humongous allocations, though. 897 dirty_young_block(result, word_size); 898 } 899 return result; 900 } else { 901 assert(op.result() == NULL, 902 "the result should be NULL if the VM op did not succeed"); 903 } 904 905 // Give a warning if we seem to be looping forever. 906 if ((QueuedAllocationWarningCount > 0) && 907 (try_count % QueuedAllocationWarningCount == 0)) { 908 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 909 } 910 } 911 912 ShouldNotReachHere(); 913 return NULL; 914 } 915 916 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 917 unsigned int *gc_count_before_ret) { 918 // Make sure you read the note in attempt_allocation_humongous(). 919 920 assert_heap_not_locked_and_not_at_safepoint(); 921 assert(!isHumongous(word_size), "attempt_allocation_slow() should not " 922 "be called for humongous allocation requests"); 923 924 // We should only get here after the first-level allocation attempt 925 // (attempt_allocation()) failed to allocate. 926 927 // We will loop until a) we manage to successfully perform the 928 // allocation or b) we successfully schedule a collection which 929 // fails to perform the allocation. b) is the only case when we'll 930 // return NULL. 931 HeapWord* result = NULL; 932 for (int try_count = 1; /* we'll return */; try_count += 1) { 933 bool should_try_gc; 934 unsigned int gc_count_before; 935 936 { 937 MutexLockerEx x(Heap_lock); 938 939 result = _mutator_alloc_region.attempt_allocation_locked(word_size, 940 false /* bot_updates */); 941 if (result != NULL) { 942 return result; 943 } 944 945 // If we reach here, attempt_allocation_locked() above failed to 946 // allocate a new region. So the mutator alloc region should be NULL. 947 assert(_mutator_alloc_region.get() == NULL, "only way to get here"); 948 949 if (GC_locker::is_active_and_needs_gc()) { 950 if (g1_policy()->can_expand_young_list()) { 951 // No need for an ergo verbose message here, 952 // can_expand_young_list() does this when it returns true. 953 result = _mutator_alloc_region.attempt_allocation_force(word_size, 954 false /* bot_updates */); 955 if (result != NULL) { 956 return result; 957 } 958 } 959 should_try_gc = false; 960 } else { 961 // The GCLocker may not be active but the GCLocker initiated 962 // GC may not yet have been performed (GCLocker::needs_gc() 963 // returns true). In this case we do not try this GC and 964 // wait until the GCLocker initiated GC is performed, and 965 // then retry the allocation. 966 if (GC_locker::needs_gc()) { 967 should_try_gc = false; 968 } else { 969 // Read the GC count while still holding the Heap_lock. 970 gc_count_before = total_collections(); 971 should_try_gc = true; 972 } 973 } 974 } 975 976 if (should_try_gc) { 977 bool succeeded; 978 result = do_collection_pause(word_size, gc_count_before, &succeeded); 979 if (result != NULL) { 980 assert(succeeded, "only way to get back a non-NULL result"); 981 return result; 982 } 983 984 if (succeeded) { 985 // If we get here we successfully scheduled a collection which 986 // failed to allocate. No point in trying to allocate 987 // further. We'll just return NULL. 988 MutexLockerEx x(Heap_lock); 989 *gc_count_before_ret = total_collections(); 990 return NULL; 991 } 992 } else { 993 // The GCLocker is either active or the GCLocker initiated 994 // GC has not yet been performed. Stall until it is and 995 // then retry the allocation. 996 GC_locker::stall_until_clear(); 997 } 998 999 // We can reach here if we were unsuccessful in scheduling a 1000 // collection (because another thread beat us to it) or if we were 1001 // stalled due to the GC locker. In either can we should retry the 1002 // allocation attempt in case another thread successfully 1003 // performed a collection and reclaimed enough space. We do the 1004 // first attempt (without holding the Heap_lock) here and the 1005 // follow-on attempt will be at the start of the next loop 1006 // iteration (after taking the Heap_lock). 1007 result = _mutator_alloc_region.attempt_allocation(word_size, 1008 false /* bot_updates */); 1009 if (result != NULL) { 1010 return result; 1011 } 1012 1013 // Give a warning if we seem to be looping forever. 1014 if ((QueuedAllocationWarningCount > 0) && 1015 (try_count % QueuedAllocationWarningCount == 0)) { 1016 warning("G1CollectedHeap::attempt_allocation_slow() " 1017 "retries %d times", try_count); 1018 } 1019 } 1020 1021 ShouldNotReachHere(); 1022 return NULL; 1023 } 1024 1025 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 1026 unsigned int * gc_count_before_ret) { 1027 // The structure of this method has a lot of similarities to 1028 // attempt_allocation_slow(). The reason these two were not merged 1029 // into a single one is that such a method would require several "if 1030 // allocation is not humongous do this, otherwise do that" 1031 // conditional paths which would obscure its flow. In fact, an early 1032 // version of this code did use a unified method which was harder to 1033 // follow and, as a result, it had subtle bugs that were hard to 1034 // track down. So keeping these two methods separate allows each to 1035 // be more readable. It will be good to keep these two in sync as 1036 // much as possible. 1037 1038 assert_heap_not_locked_and_not_at_safepoint(); 1039 assert(isHumongous(word_size), "attempt_allocation_humongous() " 1040 "should only be called for humongous allocations"); 1041 1042 // Humongous objects can exhaust the heap quickly, so we should check if we 1043 // need to start a marking cycle at each humongous object allocation. We do 1044 // the check before we do the actual allocation. The reason for doing it 1045 // before the allocation is that we avoid having to keep track of the newly 1046 // allocated memory while we do a GC. 1047 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1048 word_size)) { 1049 collect(GCCause::_g1_humongous_allocation); 1050 } 1051 1052 // We will loop until a) we manage to successfully perform the 1053 // allocation or b) we successfully schedule a collection which 1054 // fails to perform the allocation. b) is the only case when we'll 1055 // return NULL. 1056 HeapWord* result = NULL; 1057 for (int try_count = 1; /* we'll return */; try_count += 1) { 1058 bool should_try_gc; 1059 unsigned int gc_count_before; 1060 1061 { 1062 MutexLockerEx x(Heap_lock); 1063 1064 // Given that humongous objects are not allocated in young 1065 // regions, we'll first try to do the allocation without doing a 1066 // collection hoping that there's enough space in the heap. 1067 result = humongous_obj_allocate(word_size); 1068 if (result != NULL) { 1069 return result; 1070 } 1071 1072 if (GC_locker::is_active_and_needs_gc()) { 1073 should_try_gc = false; 1074 } else { 1075 // The GCLocker may not be active but the GCLocker initiated 1076 // GC may not yet have been performed (GCLocker::needs_gc() 1077 // returns true). In this case we do not try this GC and 1078 // wait until the GCLocker initiated GC is performed, and 1079 // then retry the allocation. 1080 if (GC_locker::needs_gc()) { 1081 should_try_gc = false; 1082 } else { 1083 // Read the GC count while still holding the Heap_lock. 1084 gc_count_before = total_collections(); 1085 should_try_gc = true; 1086 } 1087 } 1088 } 1089 1090 if (should_try_gc) { 1091 // If we failed to allocate the humongous object, we should try to 1092 // do a collection pause (if we're allowed) in case it reclaims 1093 // enough space for the allocation to succeed after the pause. 1094 1095 bool succeeded; 1096 result = do_collection_pause(word_size, gc_count_before, &succeeded); 1097 if (result != NULL) { 1098 assert(succeeded, "only way to get back a non-NULL result"); 1099 return result; 1100 } 1101 1102 if (succeeded) { 1103 // If we get here we successfully scheduled a collection which 1104 // failed to allocate. No point in trying to allocate 1105 // further. We'll just return NULL. 1106 MutexLockerEx x(Heap_lock); 1107 *gc_count_before_ret = total_collections(); 1108 return NULL; 1109 } 1110 } else { 1111 // The GCLocker is either active or the GCLocker initiated 1112 // GC has not yet been performed. Stall until it is and 1113 // then retry the allocation. 1114 GC_locker::stall_until_clear(); 1115 } 1116 1117 // We can reach here if we were unsuccessful in scheduling a 1118 // collection (because another thread beat us to it) or if we were 1119 // stalled due to the GC locker. In either can we should retry the 1120 // allocation attempt in case another thread successfully 1121 // performed a collection and reclaimed enough space. Give a 1122 // warning if we seem to be looping forever. 1123 1124 if ((QueuedAllocationWarningCount > 0) && 1125 (try_count % QueuedAllocationWarningCount == 0)) { 1126 warning("G1CollectedHeap::attempt_allocation_humongous() " 1127 "retries %d times", try_count); 1128 } 1129 } 1130 1131 ShouldNotReachHere(); 1132 return NULL; 1133 } 1134 1135 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1136 bool expect_null_mutator_alloc_region) { 1137 assert_at_safepoint(true /* should_be_vm_thread */); 1138 assert(_mutator_alloc_region.get() == NULL || 1139 !expect_null_mutator_alloc_region, 1140 "the current alloc region was unexpectedly found to be non-NULL"); 1141 1142 if (!isHumongous(word_size)) { 1143 return _mutator_alloc_region.attempt_allocation_locked(word_size, 1144 false /* bot_updates */); 1145 } else { 1146 HeapWord* result = humongous_obj_allocate(word_size); 1147 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1148 g1_policy()->set_initiate_conc_mark_if_possible(); 1149 } 1150 return result; 1151 } 1152 1153 ShouldNotReachHere(); 1154 } 1155 1156 class PostMCRemSetClearClosure: public HeapRegionClosure { 1157 G1CollectedHeap* _g1h; 1158 ModRefBarrierSet* _mr_bs; 1159 public: 1160 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1161 _g1h(g1h), _mr_bs(mr_bs) { } 1162 bool doHeapRegion(HeapRegion* r) { 1163 if (r->continuesHumongous()) { 1164 return false; 1165 } 1166 _g1h->reset_gc_time_stamps(r); 1167 HeapRegionRemSet* hrrs = r->rem_set(); 1168 if (hrrs != NULL) hrrs->clear(); 1169 // You might think here that we could clear just the cards 1170 // corresponding to the used region. But no: if we leave a dirty card 1171 // in a region we might allocate into, then it would prevent that card 1172 // from being enqueued, and cause it to be missed. 1173 // Re: the performance cost: we shouldn't be doing full GC anyway! 1174 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1175 return false; 1176 } 1177 }; 1178 1179 void G1CollectedHeap::clear_rsets_post_compaction() { 1180 PostMCRemSetClearClosure rs_clear(this, mr_bs()); 1181 heap_region_iterate(&rs_clear); 1182 } 1183 1184 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1185 G1CollectedHeap* _g1h; 1186 UpdateRSOopClosure _cl; 1187 int _worker_i; 1188 public: 1189 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) : 1190 _cl(g1->g1_rem_set(), worker_i), 1191 _worker_i(worker_i), 1192 _g1h(g1) 1193 { } 1194 1195 bool doHeapRegion(HeapRegion* r) { 1196 if (!r->continuesHumongous()) { 1197 _cl.set_from(r); 1198 r->oop_iterate(&_cl); 1199 } 1200 return false; 1201 } 1202 }; 1203 1204 class ParRebuildRSTask: public AbstractGangTask { 1205 G1CollectedHeap* _g1; 1206 public: 1207 ParRebuildRSTask(G1CollectedHeap* g1) 1208 : AbstractGangTask("ParRebuildRSTask"), 1209 _g1(g1) 1210 { } 1211 1212 void work(uint worker_id) { 1213 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1214 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id, 1215 _g1->workers()->active_workers(), 1216 HeapRegion::RebuildRSClaimValue); 1217 } 1218 }; 1219 1220 class PostCompactionPrinterClosure: public HeapRegionClosure { 1221 private: 1222 G1HRPrinter* _hr_printer; 1223 public: 1224 bool doHeapRegion(HeapRegion* hr) { 1225 assert(!hr->is_young(), "not expecting to find young regions"); 1226 // We only generate output for non-empty regions. 1227 if (!hr->is_empty()) { 1228 if (!hr->isHumongous()) { 1229 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1230 } else if (hr->startsHumongous()) { 1231 if (hr->region_num() == 1) { 1232 // single humongous region 1233 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1234 } else { 1235 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1236 } 1237 } else { 1238 assert(hr->continuesHumongous(), "only way to get here"); 1239 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1240 } 1241 } 1242 return false; 1243 } 1244 1245 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1246 : _hr_printer(hr_printer) { } 1247 }; 1248 1249 void G1CollectedHeap::print_hrs_post_compaction() { 1250 PostCompactionPrinterClosure cl(hr_printer()); 1251 heap_region_iterate(&cl); 1252 } 1253 1254 double G1CollectedHeap::verify(bool guard, const char* msg) { 1255 double verify_time_ms = 0.0; 1256 1257 if (guard && total_collections() >= VerifyGCStartAt) { 1258 double verify_start = os::elapsedTime(); 1259 HandleMark hm; // Discard invalid handles created during verification 1260 gclog_or_tty->print(msg); 1261 prepare_for_verify(); 1262 Universe::verify(false /* silent */, VerifyOption_G1UsePrevMarking); 1263 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 1264 } 1265 1266 return verify_time_ms; 1267 } 1268 1269 void G1CollectedHeap::verify_before_gc() { 1270 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 1271 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 1272 } 1273 1274 void G1CollectedHeap::verify_after_gc() { 1275 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 1276 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 1277 } 1278 1279 bool G1CollectedHeap::do_collection(bool explicit_gc, 1280 bool clear_all_soft_refs, 1281 size_t word_size) { 1282 assert_at_safepoint(true /* should_be_vm_thread */); 1283 1284 if (GC_locker::check_active_before_gc()) { 1285 return false; 1286 } 1287 1288 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1289 gc_timer->register_gc_start(os::elapsed_counter()); 1290 1291 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1292 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1293 1294 SvcGCMarker sgcm(SvcGCMarker::FULL); 1295 ResourceMark rm; 1296 1297 print_heap_before_gc(); 1298 trace_heap_before_gc(gc_tracer); 1299 1300 HRSPhaseSetter x(HRSPhaseFullGC); 1301 verify_region_sets_optional(); 1302 1303 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1304 collector_policy()->should_clear_all_soft_refs(); 1305 1306 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1307 1308 { 1309 IsGCActiveMark x; 1310 1311 // Timing 1312 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); 1313 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps); 1314 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1315 1316 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL); 1317 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1318 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1319 1320 double start = os::elapsedTime(); 1321 g1_policy()->record_full_collection_start(); 1322 1323 // Note: When we have a more flexible GC logging framework that 1324 // allows us to add optional attributes to a GC log record we 1325 // could consider timing and reporting how long we wait in the 1326 // following two methods. 1327 wait_while_free_regions_coming(); 1328 // If we start the compaction before the CM threads finish 1329 // scanning the root regions we might trip them over as we'll 1330 // be moving objects / updating references. So let's wait until 1331 // they are done. By telling them to abort, they should complete 1332 // early. 1333 _cm->root_regions()->abort(); 1334 _cm->root_regions()->wait_until_scan_finished(); 1335 append_secondary_free_list_if_not_empty_with_lock(); 1336 1337 gc_prologue(true); 1338 increment_total_collections(true /* full gc */); 1339 increment_old_marking_cycles_started(); 1340 1341 size_t g1h_prev_used = used(); 1342 assert(used() == recalculate_used(), "Should be equal"); 1343 1344 verify_before_gc(); 1345 1346 pre_full_gc_dump(gc_timer); 1347 1348 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1349 1350 // Disable discovery and empty the discovered lists 1351 // for the CM ref processor. 1352 ref_processor_cm()->disable_discovery(); 1353 ref_processor_cm()->abandon_partial_discovery(); 1354 ref_processor_cm()->verify_no_references_recorded(); 1355 1356 // Abandon current iterations of concurrent marking and concurrent 1357 // refinement, if any are in progress. We have to do this before 1358 // wait_until_scan_finished() below. 1359 concurrent_mark()->abort(); 1360 1361 // Make sure we'll choose a new allocation region afterwards. 1362 release_mutator_alloc_region(); 1363 abandon_gc_alloc_regions(); 1364 g1_rem_set()->cleanupHRRS(); 1365 1366 // We should call this after we retire any currently active alloc 1367 // regions so that all the ALLOC / RETIRE events are generated 1368 // before the start GC event. 1369 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1370 1371 // We may have added regions to the current incremental collection 1372 // set between the last GC or pause and now. We need to clear the 1373 // incremental collection set and then start rebuilding it afresh 1374 // after this full GC. 1375 abandon_collection_set(g1_policy()->inc_cset_head()); 1376 g1_policy()->clear_incremental_cset(); 1377 g1_policy()->stop_incremental_cset_building(); 1378 1379 tear_down_region_sets(false /* free_list_only */); 1380 g1_policy()->set_gcs_are_young(true); 1381 1382 // See the comments in g1CollectedHeap.hpp and 1383 // G1CollectedHeap::ref_processing_init() about 1384 // how reference processing currently works in G1. 1385 1386 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1387 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1388 1389 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1390 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1391 1392 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 1393 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1394 1395 // Do collection work 1396 { 1397 HandleMark hm; // Discard invalid handles created during gc 1398 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1399 } 1400 1401 assert(free_regions() == 0, "we should not have added any free regions"); 1402 rebuild_region_sets(false /* free_list_only */); 1403 1404 // Enqueue any discovered reference objects that have 1405 // not been removed from the discovered lists. 1406 ref_processor_stw()->enqueue_discovered_references(); 1407 1408 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1409 1410 MemoryService::track_memory_usage(); 1411 1412 verify_after_gc(); 1413 1414 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1415 ref_processor_stw()->verify_no_references_recorded(); 1416 1417 // Note: since we've just done a full GC, concurrent 1418 // marking is no longer active. Therefore we need not 1419 // re-enable reference discovery for the CM ref processor. 1420 // That will be done at the start of the next marking cycle. 1421 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1422 ref_processor_cm()->verify_no_references_recorded(); 1423 1424 reset_gc_time_stamp(); 1425 // Since everything potentially moved, we will clear all remembered 1426 // sets, and clear all cards. Later we will rebuild remembered 1427 // sets. We will also reset the GC time stamps of the regions. 1428 clear_rsets_post_compaction(); 1429 check_gc_time_stamps(); 1430 1431 // Resize the heap if necessary. 1432 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1433 1434 if (_hr_printer.is_active()) { 1435 // We should do this after we potentially resize the heap so 1436 // that all the COMMIT / UNCOMMIT events are generated before 1437 // the end GC event. 1438 1439 print_hrs_post_compaction(); 1440 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1441 } 1442 1443 if (_cg1r->use_cache()) { 1444 _cg1r->clear_and_record_card_counts(); 1445 _cg1r->clear_hot_cache(); 1446 } 1447 1448 // Rebuild remembered sets of all regions. 1449 if (G1CollectedHeap::use_parallel_gc_threads()) { 1450 uint n_workers = 1451 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1452 workers()->active_workers(), 1453 Threads::number_of_non_daemon_threads()); 1454 assert(UseDynamicNumberOfGCThreads || 1455 n_workers == workers()->total_workers(), 1456 "If not dynamic should be using all the workers"); 1457 workers()->set_active_workers(n_workers); 1458 // Set parallel threads in the heap (_n_par_threads) only 1459 // before a parallel phase and always reset it to 0 after 1460 // the phase so that the number of parallel threads does 1461 // no get carried forward to a serial phase where there 1462 // may be code that is "possibly_parallel". 1463 set_par_threads(n_workers); 1464 1465 ParRebuildRSTask rebuild_rs_task(this); 1466 assert(check_heap_region_claim_values( 1467 HeapRegion::InitialClaimValue), "sanity check"); 1468 assert(UseDynamicNumberOfGCThreads || 1469 workers()->active_workers() == workers()->total_workers(), 1470 "Unless dynamic should use total workers"); 1471 // Use the most recent number of active workers 1472 assert(workers()->active_workers() > 0, 1473 "Active workers not properly set"); 1474 set_par_threads(workers()->active_workers()); 1475 workers()->run_task(&rebuild_rs_task); 1476 set_par_threads(0); 1477 assert(check_heap_region_claim_values( 1478 HeapRegion::RebuildRSClaimValue), "sanity check"); 1479 reset_heap_region_claim_values(); 1480 } else { 1481 RebuildRSOutOfRegionClosure rebuild_rs(this); 1482 heap_region_iterate(&rebuild_rs); 1483 } 1484 1485 if (G1Log::fine()) { 1486 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity()); 1487 } 1488 1489 if (true) { // FIXME 1490 // Ask the permanent generation to adjust size for full collections 1491 perm()->compute_new_size(); 1492 } 1493 1494 // Start a new incremental collection set for the next pause 1495 assert(g1_policy()->collection_set() == NULL, "must be"); 1496 g1_policy()->start_incremental_cset_building(); 1497 1498 // Clear the _cset_fast_test bitmap in anticipation of adding 1499 // regions to the incremental collection set for the next 1500 // evacuation pause. 1501 clear_cset_fast_test(); 1502 1503 init_mutator_alloc_region(); 1504 1505 double end = os::elapsedTime(); 1506 g1_policy()->record_full_collection_end(); 1507 1508 #ifdef TRACESPINNING 1509 ParallelTaskTerminator::print_termination_counts(); 1510 #endif 1511 1512 gc_epilogue(true); 1513 1514 // Discard all rset updates 1515 JavaThread::dirty_card_queue_set().abandon_logs(); 1516 assert(!G1DeferredRSUpdate 1517 || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any"); 1518 1519 _young_list->reset_sampled_info(); 1520 // At this point there should be no regions in the 1521 // entire heap tagged as young. 1522 assert( check_young_list_empty(true /* check_heap */), 1523 "young list should be empty at this point"); 1524 1525 // Update the number of full collections that have been completed. 1526 increment_old_marking_cycles_completed(false /* concurrent */); 1527 1528 _hrs.verify_optional(); 1529 verify_region_sets_optional(); 1530 1531 print_heap_after_gc(); 1532 trace_heap_after_gc(gc_tracer); 1533 1534 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1535 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1536 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1537 // before any GC notifications are raised. 1538 g1mm()->update_sizes(); 1539 } 1540 1541 post_full_gc_dump(gc_timer); 1542 1543 gc_timer->register_gc_end(os::elapsed_counter()); 1544 1545 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1546 1547 return true; 1548 } 1549 1550 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1551 // do_collection() will return whether it succeeded in performing 1552 // the GC. Currently, there is no facility on the 1553 // do_full_collection() API to notify the caller than the collection 1554 // did not succeed (e.g., because it was locked out by the GC 1555 // locker). So, right now, we'll ignore the return value. 1556 bool dummy = do_collection(true, /* explicit_gc */ 1557 clear_all_soft_refs, 1558 0 /* word_size */); 1559 } 1560 1561 // This code is mostly copied from TenuredGeneration. 1562 void 1563 G1CollectedHeap:: 1564 resize_if_necessary_after_full_collection(size_t word_size) { 1565 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check"); 1566 1567 // Include the current allocation, if any, and bytes that will be 1568 // pre-allocated to support collections, as "used". 1569 const size_t used_after_gc = used(); 1570 const size_t capacity_after_gc = capacity(); 1571 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1572 1573 // This is enforced in arguments.cpp. 1574 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1575 "otherwise the code below doesn't make sense"); 1576 1577 // We don't have floating point command-line arguments 1578 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1579 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1580 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1581 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1582 1583 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1584 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1585 1586 // We have to be careful here as these two calculations can overflow 1587 // 32-bit size_t's. 1588 double used_after_gc_d = (double) used_after_gc; 1589 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1590 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1591 1592 // Let's make sure that they are both under the max heap size, which 1593 // by default will make them fit into a size_t. 1594 double desired_capacity_upper_bound = (double) max_heap_size; 1595 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1596 desired_capacity_upper_bound); 1597 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1598 desired_capacity_upper_bound); 1599 1600 // We can now safely turn them into size_t's. 1601 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1602 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1603 1604 // This assert only makes sense here, before we adjust them 1605 // with respect to the min and max heap size. 1606 assert(minimum_desired_capacity <= maximum_desired_capacity, 1607 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1608 "maximum_desired_capacity = "SIZE_FORMAT, 1609 minimum_desired_capacity, maximum_desired_capacity)); 1610 1611 // Should not be greater than the heap max size. No need to adjust 1612 // it with respect to the heap min size as it's a lower bound (i.e., 1613 // we'll try to make the capacity larger than it, not smaller). 1614 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1615 // Should not be less than the heap min size. No need to adjust it 1616 // with respect to the heap max size as it's an upper bound (i.e., 1617 // we'll try to make the capacity smaller than it, not greater). 1618 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1619 1620 if (capacity_after_gc < minimum_desired_capacity) { 1621 // Don't expand unless it's significant 1622 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1623 ergo_verbose4(ErgoHeapSizing, 1624 "attempt heap expansion", 1625 ergo_format_reason("capacity lower than " 1626 "min desired capacity after Full GC") 1627 ergo_format_byte("capacity") 1628 ergo_format_byte("occupancy") 1629 ergo_format_byte_perc("min desired capacity"), 1630 capacity_after_gc, used_after_gc, 1631 minimum_desired_capacity, (double) MinHeapFreeRatio); 1632 expand(expand_bytes); 1633 1634 // No expansion, now see if we want to shrink 1635 } else if (capacity_after_gc > maximum_desired_capacity) { 1636 // Capacity too large, compute shrinking size 1637 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1638 ergo_verbose4(ErgoHeapSizing, 1639 "attempt heap shrinking", 1640 ergo_format_reason("capacity higher than " 1641 "max desired capacity after Full GC") 1642 ergo_format_byte("capacity") 1643 ergo_format_byte("occupancy") 1644 ergo_format_byte_perc("max desired capacity"), 1645 capacity_after_gc, used_after_gc, 1646 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1647 shrink(shrink_bytes); 1648 } 1649 } 1650 1651 1652 HeapWord* 1653 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1654 bool* succeeded) { 1655 assert_at_safepoint(true /* should_be_vm_thread */); 1656 1657 *succeeded = true; 1658 // Let's attempt the allocation first. 1659 HeapWord* result = 1660 attempt_allocation_at_safepoint(word_size, 1661 false /* expect_null_mutator_alloc_region */); 1662 if (result != NULL) { 1663 assert(*succeeded, "sanity"); 1664 return result; 1665 } 1666 1667 // In a G1 heap, we're supposed to keep allocation from failing by 1668 // incremental pauses. Therefore, at least for now, we'll favor 1669 // expansion over collection. (This might change in the future if we can 1670 // do something smarter than full collection to satisfy a failed alloc.) 1671 result = expand_and_allocate(word_size); 1672 if (result != NULL) { 1673 assert(*succeeded, "sanity"); 1674 return result; 1675 } 1676 1677 // Expansion didn't work, we'll try to do a Full GC. 1678 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1679 false, /* clear_all_soft_refs */ 1680 word_size); 1681 if (!gc_succeeded) { 1682 *succeeded = false; 1683 return NULL; 1684 } 1685 1686 // Retry the allocation 1687 result = attempt_allocation_at_safepoint(word_size, 1688 true /* expect_null_mutator_alloc_region */); 1689 if (result != NULL) { 1690 assert(*succeeded, "sanity"); 1691 return result; 1692 } 1693 1694 // Then, try a Full GC that will collect all soft references. 1695 gc_succeeded = do_collection(false, /* explicit_gc */ 1696 true, /* clear_all_soft_refs */ 1697 word_size); 1698 if (!gc_succeeded) { 1699 *succeeded = false; 1700 return NULL; 1701 } 1702 1703 // Retry the allocation once more 1704 result = attempt_allocation_at_safepoint(word_size, 1705 true /* expect_null_mutator_alloc_region */); 1706 if (result != NULL) { 1707 assert(*succeeded, "sanity"); 1708 return result; 1709 } 1710 1711 assert(!collector_policy()->should_clear_all_soft_refs(), 1712 "Flag should have been handled and cleared prior to this point"); 1713 1714 // What else? We might try synchronous finalization later. If the total 1715 // space available is large enough for the allocation, then a more 1716 // complete compaction phase than we've tried so far might be 1717 // appropriate. 1718 assert(*succeeded, "sanity"); 1719 return NULL; 1720 } 1721 1722 // Attempting to expand the heap sufficiently 1723 // to support an allocation of the given "word_size". If 1724 // successful, perform the allocation and return the address of the 1725 // allocated block, or else "NULL". 1726 1727 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1728 assert_at_safepoint(true /* should_be_vm_thread */); 1729 1730 verify_region_sets_optional(); 1731 1732 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1733 ergo_verbose1(ErgoHeapSizing, 1734 "attempt heap expansion", 1735 ergo_format_reason("allocation request failed") 1736 ergo_format_byte("allocation request"), 1737 word_size * HeapWordSize); 1738 if (expand(expand_bytes)) { 1739 _hrs.verify_optional(); 1740 verify_region_sets_optional(); 1741 return attempt_allocation_at_safepoint(word_size, 1742 false /* expect_null_mutator_alloc_region */); 1743 } 1744 return NULL; 1745 } 1746 1747 void G1CollectedHeap::update_committed_space(HeapWord* old_end, 1748 HeapWord* new_end) { 1749 assert(old_end != new_end, "don't call this otherwise"); 1750 assert((HeapWord*) _g1_storage.high() == new_end, "invariant"); 1751 1752 // Update the committed mem region. 1753 _g1_committed.set_end(new_end); 1754 // Tell the card table about the update. 1755 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed); 1756 // Tell the BOT about the update. 1757 _bot_shared->resize(_g1_committed.word_size()); 1758 } 1759 1760 bool G1CollectedHeap::expand(size_t expand_bytes) { 1761 size_t old_mem_size = _g1_storage.committed_size(); 1762 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1763 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1764 HeapRegion::GrainBytes); 1765 ergo_verbose2(ErgoHeapSizing, 1766 "expand the heap", 1767 ergo_format_byte("requested expansion amount") 1768 ergo_format_byte("attempted expansion amount"), 1769 expand_bytes, aligned_expand_bytes); 1770 1771 // First commit the memory. 1772 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1773 bool successful = _g1_storage.expand_by(aligned_expand_bytes); 1774 if (successful) { 1775 // Then propagate this update to the necessary data structures. 1776 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1777 update_committed_space(old_end, new_end); 1778 1779 FreeRegionList expansion_list("Local Expansion List"); 1780 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list); 1781 assert(mr.start() == old_end, "post-condition"); 1782 // mr might be a smaller region than what was requested if 1783 // expand_by() was unable to allocate the HeapRegion instances 1784 assert(mr.end() <= new_end, "post-condition"); 1785 1786 size_t actual_expand_bytes = mr.byte_size(); 1787 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1788 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(), 1789 "post-condition"); 1790 if (actual_expand_bytes < aligned_expand_bytes) { 1791 // We could not expand _hrs to the desired size. In this case we 1792 // need to shrink the committed space accordingly. 1793 assert(mr.end() < new_end, "invariant"); 1794 1795 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes; 1796 // First uncommit the memory. 1797 _g1_storage.shrink_by(diff_bytes); 1798 // Then propagate this update to the necessary data structures. 1799 update_committed_space(new_end, mr.end()); 1800 } 1801 _free_list.add_as_tail(&expansion_list); 1802 1803 if (_hr_printer.is_active()) { 1804 HeapWord* curr = mr.start(); 1805 while (curr < mr.end()) { 1806 HeapWord* curr_end = curr + HeapRegion::GrainWords; 1807 _hr_printer.commit(curr, curr_end); 1808 curr = curr_end; 1809 } 1810 assert(curr == mr.end(), "post-condition"); 1811 } 1812 g1_policy()->record_new_heap_size(n_regions()); 1813 } else { 1814 ergo_verbose0(ErgoHeapSizing, 1815 "did not expand the heap", 1816 ergo_format_reason("heap expansion operation failed")); 1817 // The expansion of the virtual storage space was unsuccessful. 1818 // Let's see if it was because we ran out of swap. 1819 if (G1ExitOnExpansionFailure && 1820 _g1_storage.uncommitted_size() >= aligned_expand_bytes) { 1821 // We had head room... 1822 vm_exit_out_of_memory(aligned_expand_bytes, "G1 heap expansion"); 1823 } 1824 } 1825 return successful; 1826 } 1827 1828 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1829 size_t old_mem_size = _g1_storage.committed_size(); 1830 size_t aligned_shrink_bytes = 1831 ReservedSpace::page_align_size_down(shrink_bytes); 1832 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, 1833 HeapRegion::GrainBytes); 1834 uint num_regions_deleted = 0; 1835 MemRegion mr = _hrs.shrink_by(aligned_shrink_bytes, &num_regions_deleted); 1836 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1837 assert(mr.end() == old_end, "post-condition"); 1838 1839 ergo_verbose3(ErgoHeapSizing, 1840 "shrink the heap", 1841 ergo_format_byte("requested shrinking amount") 1842 ergo_format_byte("aligned shrinking amount") 1843 ergo_format_byte("attempted shrinking amount"), 1844 shrink_bytes, aligned_shrink_bytes, mr.byte_size()); 1845 if (mr.byte_size() > 0) { 1846 if (_hr_printer.is_active()) { 1847 HeapWord* curr = mr.end(); 1848 while (curr > mr.start()) { 1849 HeapWord* curr_end = curr; 1850 curr -= HeapRegion::GrainWords; 1851 _hr_printer.uncommit(curr, curr_end); 1852 } 1853 assert(curr == mr.start(), "post-condition"); 1854 } 1855 1856 _g1_storage.shrink_by(mr.byte_size()); 1857 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1858 assert(mr.start() == new_end, "post-condition"); 1859 1860 _expansion_regions += num_regions_deleted; 1861 update_committed_space(old_end, new_end); 1862 HeapRegionRemSet::shrink_heap(n_regions()); 1863 g1_policy()->record_new_heap_size(n_regions()); 1864 } else { 1865 ergo_verbose0(ErgoHeapSizing, 1866 "did not shrink the heap", 1867 ergo_format_reason("heap shrinking operation failed")); 1868 } 1869 } 1870 1871 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1872 verify_region_sets_optional(); 1873 1874 // We should only reach here at the end of a Full GC which means we 1875 // should not not be holding to any GC alloc regions. The method 1876 // below will make sure of that and do any remaining clean up. 1877 abandon_gc_alloc_regions(); 1878 1879 // Instead of tearing down / rebuilding the free lists here, we 1880 // could instead use the remove_all_pending() method on free_list to 1881 // remove only the ones that we need to remove. 1882 tear_down_region_sets(true /* free_list_only */); 1883 shrink_helper(shrink_bytes); 1884 rebuild_region_sets(true /* free_list_only */); 1885 1886 _hrs.verify_optional(); 1887 verify_region_sets_optional(); 1888 } 1889 1890 // Public methods. 1891 1892 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1893 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1894 #endif // _MSC_VER 1895 1896 1897 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1898 SharedHeap(policy_), 1899 _g1_policy(policy_), 1900 _dirty_card_queue_set(false), 1901 _into_cset_dirty_card_queue_set(false), 1902 _is_alive_closure_cm(this), 1903 _is_alive_closure_stw(this), 1904 _ref_processor_cm(NULL), 1905 _ref_processor_stw(NULL), 1906 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)), 1907 _bot_shared(NULL), 1908 _evac_failure_scan_stack(NULL), 1909 _mark_in_progress(false), 1910 _cg1r(NULL), _summary_bytes_used(0), 1911 _g1mm(NULL), 1912 _refine_cte_cl(NULL), 1913 _full_collection(false), 1914 _free_list("Master Free List"), 1915 _secondary_free_list("Secondary Free List"), 1916 _old_set("Old Set"), 1917 _humongous_set("Master Humongous Set"), 1918 _free_regions_coming(false), 1919 _young_list(new YoungList(this)), 1920 _gc_time_stamp(0), 1921 _retained_old_gc_alloc_region(NULL), 1922 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1923 _old_plab_stats(OldPLABSize, PLABWeight), 1924 _expand_heap_after_alloc_failure(true), 1925 _surviving_young_words(NULL), 1926 _old_marking_cycles_started(0), 1927 _old_marking_cycles_completed(0), 1928 _concurrent_cycle_started(false), 1929 _in_cset_fast_test(NULL), 1930 _in_cset_fast_test_base(NULL), 1931 _dirty_cards_region_list(NULL), 1932 _worker_cset_start_region(NULL), 1933 _worker_cset_start_region_time_stamp(NULL), 1934 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1935 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1936 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1937 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1938 1939 _g1h = this; 1940 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) { 1941 vm_exit_during_initialization("Failed necessary allocation."); 1942 } 1943 1944 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1945 1946 int n_queues = MAX2((int)ParallelGCThreads, 1); 1947 _task_queues = new RefToScanQueueSet(n_queues); 1948 1949 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1950 assert(n_rem_sets > 0, "Invariant."); 1951 1952 HeapRegionRemSetIterator** iter_arr = NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues, mtGC); 1953 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1954 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC); 1955 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1956 1957 for (int i = 0; i < n_queues; i++) { 1958 RefToScanQueue* q = new RefToScanQueue(); 1959 q->initialize(); 1960 _task_queues->register_queue(i, q); 1961 iter_arr[i] = new HeapRegionRemSetIterator(); 1962 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1963 } 1964 _rem_set_iterator = iter_arr; 1965 1966 clear_cset_start_regions(); 1967 1968 // Initialize the G1EvacuationFailureALot counters and flags. 1969 NOT_PRODUCT(reset_evacuation_should_fail();) 1970 1971 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1972 } 1973 1974 jint G1CollectedHeap::initialize() { 1975 CollectedHeap::pre_initialize(); 1976 os::enable_vtime(); 1977 1978 G1Log::init(); 1979 1980 // Necessary to satisfy locking discipline assertions. 1981 1982 MutexLocker x(Heap_lock); 1983 1984 // We have to initialize the printer before committing the heap, as 1985 // it will be used then. 1986 _hr_printer.set_active(G1PrintHeapRegions); 1987 1988 // While there are no constraints in the GC code that HeapWordSize 1989 // be any particular value, there are multiple other areas in the 1990 // system which believe this to be true (e.g. oop->object_size in some 1991 // cases incorrectly returns the size in wordSize units rather than 1992 // HeapWordSize). 1993 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1994 1995 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1996 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1997 1998 // Ensure that the sizes are properly aligned. 1999 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2000 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 2001 2002 _cg1r = new ConcurrentG1Refine(); 2003 2004 // Reserve the maximum. 2005 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation(); 2006 // Includes the perm-gen. 2007 2008 // When compressed oops are enabled, the preferred heap base 2009 // is calculated by subtracting the requested size from the 2010 // 32Gb boundary and using the result as the base address for 2011 // heap reservation. If the requested size is not aligned to 2012 // HeapRegion::GrainBytes (i.e. the alignment that is passed 2013 // into the ReservedHeapSpace constructor) then the actual 2014 // base of the reserved heap may end up differing from the 2015 // address that was requested (i.e. the preferred heap base). 2016 // If this happens then we could end up using a non-optimal 2017 // compressed oops mode. 2018 2019 // Since max_byte_size is aligned to the size of a heap region (checked 2020 // above), we also need to align the perm gen size as it might not be. 2021 const size_t total_reserved = max_byte_size + 2022 align_size_up(pgs->max_size(), HeapRegion::GrainBytes); 2023 Universe::check_alignment(total_reserved, HeapRegion::GrainBytes, "g1 heap and perm"); 2024 2025 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop); 2026 2027 ReservedHeapSpace heap_rs(total_reserved, HeapRegion::GrainBytes, 2028 UseLargePages, addr); 2029 2030 if (UseCompressedOops) { 2031 if (addr != NULL && !heap_rs.is_reserved()) { 2032 // Failed to reserve at specified address - the requested memory 2033 // region is taken already, for example, by 'java' launcher. 2034 // Try again to reserver heap higher. 2035 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop); 2036 2037 ReservedHeapSpace heap_rs0(total_reserved, HeapRegion::GrainBytes, 2038 UseLargePages, addr); 2039 2040 if (addr != NULL && !heap_rs0.is_reserved()) { 2041 // Failed to reserve at specified address again - give up. 2042 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop); 2043 assert(addr == NULL, ""); 2044 2045 ReservedHeapSpace heap_rs1(total_reserved, HeapRegion::GrainBytes, 2046 UseLargePages, addr); 2047 heap_rs = heap_rs1; 2048 } else { 2049 heap_rs = heap_rs0; 2050 } 2051 } 2052 } 2053 2054 if (!heap_rs.is_reserved()) { 2055 vm_exit_during_initialization("Could not reserve enough space for object heap"); 2056 return JNI_ENOMEM; 2057 } 2058 2059 // It is important to do this in a way such that concurrent readers can't 2060 // temporarily think something is in the heap. (I've actually seen this 2061 // happen in asserts: DLD.) 2062 _reserved.set_word_size(0); 2063 _reserved.set_start((HeapWord*)heap_rs.base()); 2064 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size())); 2065 2066 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes); 2067 2068 // Create the gen rem set (and barrier set) for the entire reserved region. 2069 _rem_set = collector_policy()->create_rem_set(_reserved, 2); 2070 set_barrier_set(rem_set()->bs()); 2071 if (barrier_set()->is_a(BarrierSet::ModRef)) { 2072 _mr_bs = (ModRefBarrierSet*)_barrier_set; 2073 } else { 2074 vm_exit_during_initialization("G1 requires a mod ref bs."); 2075 return JNI_ENOMEM; 2076 } 2077 2078 // Also create a G1 rem set. 2079 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) { 2080 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs()); 2081 } else { 2082 vm_exit_during_initialization("G1 requires a cardtable mod ref bs."); 2083 return JNI_ENOMEM; 2084 } 2085 2086 // Carve out the G1 part of the heap. 2087 2088 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 2089 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(), 2090 g1_rs.size()/HeapWordSize); 2091 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size); 2092 2093 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set()); 2094 2095 _g1_storage.initialize(g1_rs, 0); 2096 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0); 2097 _hrs.initialize((HeapWord*) _g1_reserved.start(), 2098 (HeapWord*) _g1_reserved.end(), 2099 _expansion_regions); 2100 2101 // 6843694 - ensure that the maximum region index can fit 2102 // in the remembered set structures. 2103 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2104 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2105 2106 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2107 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2108 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2109 "too many cards per region"); 2110 2111 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1); 2112 2113 _bot_shared = new G1BlockOffsetSharedArray(_reserved, 2114 heap_word_size(init_byte_size)); 2115 2116 _g1h = this; 2117 2118 _in_cset_fast_test_length = max_regions(); 2119 _in_cset_fast_test_base = 2120 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC); 2121 2122 // We're biasing _in_cset_fast_test to avoid subtracting the 2123 // beginning of the heap every time we want to index; basically 2124 // it's the same with what we do with the card table. 2125 _in_cset_fast_test = _in_cset_fast_test_base - 2126 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes); 2127 2128 // Clear the _cset_fast_test bitmap in anticipation of adding 2129 // regions to the incremental collection set for the first 2130 // evacuation pause. 2131 clear_cset_fast_test(); 2132 2133 // Create the ConcurrentMark data structure and thread. 2134 // (Must do this late, so that "max_regions" is defined.) 2135 _cm = new ConcurrentMark(heap_rs, max_regions()); 2136 _cmThread = _cm->cmThread(); 2137 2138 // Initialize the from_card cache structure of HeapRegionRemSet. 2139 HeapRegionRemSet::init_heap(max_regions()); 2140 2141 // Now expand into the initial heap size. 2142 if (!expand(init_byte_size)) { 2143 vm_exit_during_initialization("Failed to allocate initial heap."); 2144 return JNI_ENOMEM; 2145 } 2146 2147 // Perform any initialization actions delegated to the policy. 2148 g1_policy()->init(); 2149 2150 _refine_cte_cl = 2151 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(), 2152 g1_rem_set(), 2153 concurrent_g1_refine()); 2154 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl); 2155 2156 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2157 SATB_Q_FL_lock, 2158 G1SATBProcessCompletedThreshold, 2159 Shared_SATB_Q_lock); 2160 2161 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 2162 DirtyCardQ_FL_lock, 2163 concurrent_g1_refine()->yellow_zone(), 2164 concurrent_g1_refine()->red_zone(), 2165 Shared_DirtyCardQ_lock); 2166 2167 if (G1DeferredRSUpdate) { 2168 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 2169 DirtyCardQ_FL_lock, 2170 -1, // never trigger processing 2171 -1, // no limit on length 2172 Shared_DirtyCardQ_lock, 2173 &JavaThread::dirty_card_queue_set()); 2174 } 2175 2176 // Initialize the card queue set used to hold cards containing 2177 // references into the collection set. 2178 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon, 2179 DirtyCardQ_FL_lock, 2180 -1, // never trigger processing 2181 -1, // no limit on length 2182 Shared_DirtyCardQ_lock, 2183 &JavaThread::dirty_card_queue_set()); 2184 2185 // In case we're keeping closure specialization stats, initialize those 2186 // counts and that mechanism. 2187 SpecializationStats::clear(); 2188 2189 // Do later initialization work for concurrent refinement. 2190 _cg1r->init(); 2191 2192 // Here we allocate the dummy full region that is required by the 2193 // G1AllocRegion class. If we don't pass an address in the reserved 2194 // space here, lots of asserts fire. 2195 2196 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */, 2197 _g1_reserved.start()); 2198 // We'll re-use the same region whether the alloc region will 2199 // require BOT updates or not and, if it doesn't, then a non-young 2200 // region will complain that it cannot support allocations without 2201 // BOT updates. So we'll tag the dummy region as young to avoid that. 2202 dummy_region->set_young(); 2203 // Make sure it's full. 2204 dummy_region->set_top(dummy_region->end()); 2205 G1AllocRegion::setup(this, dummy_region); 2206 2207 init_mutator_alloc_region(); 2208 2209 // Do create of the monitoring and management support so that 2210 // values in the heap have been properly initialized. 2211 _g1mm = new G1MonitoringSupport(this); 2212 2213 return JNI_OK; 2214 } 2215 2216 void G1CollectedHeap::ref_processing_init() { 2217 // Reference processing in G1 currently works as follows: 2218 // 2219 // * There are two reference processor instances. One is 2220 // used to record and process discovered references 2221 // during concurrent marking; the other is used to 2222 // record and process references during STW pauses 2223 // (both full and incremental). 2224 // * Both ref processors need to 'span' the entire heap as 2225 // the regions in the collection set may be dotted around. 2226 // 2227 // * For the concurrent marking ref processor: 2228 // * Reference discovery is enabled at initial marking. 2229 // * Reference discovery is disabled and the discovered 2230 // references processed etc during remarking. 2231 // * Reference discovery is MT (see below). 2232 // * Reference discovery requires a barrier (see below). 2233 // * Reference processing may or may not be MT 2234 // (depending on the value of ParallelRefProcEnabled 2235 // and ParallelGCThreads). 2236 // * A full GC disables reference discovery by the CM 2237 // ref processor and abandons any entries on it's 2238 // discovered lists. 2239 // 2240 // * For the STW processor: 2241 // * Non MT discovery is enabled at the start of a full GC. 2242 // * Processing and enqueueing during a full GC is non-MT. 2243 // * During a full GC, references are processed after marking. 2244 // 2245 // * Discovery (may or may not be MT) is enabled at the start 2246 // of an incremental evacuation pause. 2247 // * References are processed near the end of a STW evacuation pause. 2248 // * For both types of GC: 2249 // * Discovery is atomic - i.e. not concurrent. 2250 // * Reference discovery will not need a barrier. 2251 2252 SharedHeap::ref_processing_init(); 2253 MemRegion mr = reserved_region(); 2254 2255 // Concurrent Mark ref processor 2256 _ref_processor_cm = 2257 new ReferenceProcessor(mr, // span 2258 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2259 // mt processing 2260 (int) ParallelGCThreads, 2261 // degree of mt processing 2262 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2263 // mt discovery 2264 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2265 // degree of mt discovery 2266 false, 2267 // Reference discovery is not atomic 2268 &_is_alive_closure_cm, 2269 // is alive closure 2270 // (for efficiency/performance) 2271 true); 2272 // Setting next fields of discovered 2273 // lists requires a barrier. 2274 2275 // STW ref processor 2276 _ref_processor_stw = 2277 new ReferenceProcessor(mr, // span 2278 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2279 // mt processing 2280 MAX2((int)ParallelGCThreads, 1), 2281 // degree of mt processing 2282 (ParallelGCThreads > 1), 2283 // mt discovery 2284 MAX2((int)ParallelGCThreads, 1), 2285 // degree of mt discovery 2286 true, 2287 // Reference discovery is atomic 2288 &_is_alive_closure_stw, 2289 // is alive closure 2290 // (for efficiency/performance) 2291 false); 2292 // Setting next fields of discovered 2293 // lists requires a barrier. 2294 } 2295 2296 size_t G1CollectedHeap::capacity() const { 2297 return _g1_committed.byte_size(); 2298 } 2299 2300 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2301 assert(!hr->continuesHumongous(), "pre-condition"); 2302 hr->reset_gc_time_stamp(); 2303 if (hr->startsHumongous()) { 2304 uint first_index = hr->hrs_index() + 1; 2305 uint last_index = hr->last_hc_index(); 2306 for (uint i = first_index; i < last_index; i += 1) { 2307 HeapRegion* chr = region_at(i); 2308 assert(chr->continuesHumongous(), "sanity"); 2309 chr->reset_gc_time_stamp(); 2310 } 2311 } 2312 } 2313 2314 #ifndef PRODUCT 2315 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2316 private: 2317 unsigned _gc_time_stamp; 2318 bool _failures; 2319 2320 public: 2321 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2322 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2323 2324 virtual bool doHeapRegion(HeapRegion* hr) { 2325 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2326 if (_gc_time_stamp != region_gc_time_stamp) { 2327 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2328 "expected %d", HR_FORMAT_PARAMS(hr), 2329 region_gc_time_stamp, _gc_time_stamp); 2330 _failures = true; 2331 } 2332 return false; 2333 } 2334 2335 bool failures() { return _failures; } 2336 }; 2337 2338 void G1CollectedHeap::check_gc_time_stamps() { 2339 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2340 heap_region_iterate(&cl); 2341 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2342 } 2343 #endif // PRODUCT 2344 2345 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2346 DirtyCardQueue* into_cset_dcq, 2347 bool concurrent, 2348 int worker_i) { 2349 // Clean cards in the hot card cache 2350 concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq); 2351 2352 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2353 int n_completed_buffers = 0; 2354 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2355 n_completed_buffers++; 2356 } 2357 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers); 2358 dcqs.clear_n_completed_buffers(); 2359 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2360 } 2361 2362 2363 // Computes the sum of the storage used by the various regions. 2364 2365 size_t G1CollectedHeap::used() const { 2366 assert(Heap_lock->owner() != NULL, 2367 "Should be owned on this thread's behalf."); 2368 size_t result = _summary_bytes_used; 2369 // Read only once in case it is set to NULL concurrently 2370 HeapRegion* hr = _mutator_alloc_region.get(); 2371 if (hr != NULL) 2372 result += hr->used(); 2373 return result; 2374 } 2375 2376 size_t G1CollectedHeap::used_unlocked() const { 2377 size_t result = _summary_bytes_used; 2378 return result; 2379 } 2380 2381 class SumUsedClosure: public HeapRegionClosure { 2382 size_t _used; 2383 public: 2384 SumUsedClosure() : _used(0) {} 2385 bool doHeapRegion(HeapRegion* r) { 2386 if (!r->continuesHumongous()) { 2387 _used += r->used(); 2388 } 2389 return false; 2390 } 2391 size_t result() { return _used; } 2392 }; 2393 2394 size_t G1CollectedHeap::recalculate_used() const { 2395 SumUsedClosure blk; 2396 heap_region_iterate(&blk); 2397 return blk.result(); 2398 } 2399 2400 size_t G1CollectedHeap::unsafe_max_alloc() { 2401 if (free_regions() > 0) return HeapRegion::GrainBytes; 2402 // otherwise, is there space in the current allocation region? 2403 2404 // We need to store the current allocation region in a local variable 2405 // here. The problem is that this method doesn't take any locks and 2406 // there may be other threads which overwrite the current allocation 2407 // region field. attempt_allocation(), for example, sets it to NULL 2408 // and this can happen *after* the NULL check here but before the call 2409 // to free(), resulting in a SIGSEGV. Note that this doesn't appear 2410 // to be a problem in the optimized build, since the two loads of the 2411 // current allocation region field are optimized away. 2412 HeapRegion* hr = _mutator_alloc_region.get(); 2413 if (hr == NULL) { 2414 return 0; 2415 } 2416 return hr->free(); 2417 } 2418 2419 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2420 switch (cause) { 2421 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2422 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2423 case GCCause::_g1_humongous_allocation: return true; 2424 default: return false; 2425 } 2426 } 2427 2428 #ifndef PRODUCT 2429 void G1CollectedHeap::allocate_dummy_regions() { 2430 // Let's fill up most of the region 2431 size_t word_size = HeapRegion::GrainWords - 1024; 2432 // And as a result the region we'll allocate will be humongous. 2433 guarantee(isHumongous(word_size), "sanity"); 2434 2435 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2436 // Let's use the existing mechanism for the allocation 2437 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2438 if (dummy_obj != NULL) { 2439 MemRegion mr(dummy_obj, word_size); 2440 CollectedHeap::fill_with_object(mr); 2441 } else { 2442 // If we can't allocate once, we probably cannot allocate 2443 // again. Let's get out of the loop. 2444 break; 2445 } 2446 } 2447 } 2448 #endif // !PRODUCT 2449 2450 void G1CollectedHeap::increment_old_marking_cycles_started() { 2451 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2452 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2453 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2454 _old_marking_cycles_started, _old_marking_cycles_completed)); 2455 2456 _old_marking_cycles_started++; 2457 } 2458 2459 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2460 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2461 2462 // We assume that if concurrent == true, then the caller is a 2463 // concurrent thread that was joined the Suspendible Thread 2464 // Set. If there's ever a cheap way to check this, we should add an 2465 // assert here. 2466 2467 // Given that this method is called at the end of a Full GC or of a 2468 // concurrent cycle, and those can be nested (i.e., a Full GC can 2469 // interrupt a concurrent cycle), the number of full collections 2470 // completed should be either one (in the case where there was no 2471 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2472 // behind the number of full collections started. 2473 2474 // This is the case for the inner caller, i.e. a Full GC. 2475 assert(concurrent || 2476 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2477 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2478 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2479 "is inconsistent with _old_marking_cycles_completed = %u", 2480 _old_marking_cycles_started, _old_marking_cycles_completed)); 2481 2482 // This is the case for the outer caller, i.e. the concurrent cycle. 2483 assert(!concurrent || 2484 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2485 err_msg("for outer caller (concurrent cycle): " 2486 "_old_marking_cycles_started = %u " 2487 "is inconsistent with _old_marking_cycles_completed = %u", 2488 _old_marking_cycles_started, _old_marking_cycles_completed)); 2489 2490 _old_marking_cycles_completed += 1; 2491 2492 // We need to clear the "in_progress" flag in the CM thread before 2493 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2494 // is set) so that if a waiter requests another System.gc() it doesn't 2495 // incorrectly see that a marking cycle is still in progress. 2496 if (concurrent) { 2497 _cmThread->clear_in_progress(); 2498 } 2499 2500 // This notify_all() will ensure that a thread that called 2501 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2502 // and it's waiting for a full GC to finish will be woken up. It is 2503 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2504 FullGCCount_lock->notify_all(); 2505 } 2506 2507 void G1CollectedHeap::register_concurrent_cycle_start(jlong start_time) { 2508 _concurrent_cycle_started = true; 2509 _gc_timer_cm->register_gc_start(start_time); 2510 2511 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2512 trace_heap_before_gc(_gc_tracer_cm); 2513 } 2514 2515 void G1CollectedHeap::register_concurrent_cycle_end() { 2516 if (_concurrent_cycle_started) { 2517 _gc_timer_cm->register_gc_end(os::elapsed_counter()); 2518 2519 if (_cm->has_aborted()) { 2520 _gc_tracer_cm->report_concurrent_mode_failure(); 2521 } 2522 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2523 2524 _concurrent_cycle_started = false; 2525 } 2526 } 2527 2528 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2529 if (_concurrent_cycle_started) { 2530 trace_heap_after_gc(_gc_tracer_cm); 2531 } 2532 } 2533 2534 G1YCType G1CollectedHeap::yc_type() { 2535 bool is_young = g1_policy()->gcs_are_young(); 2536 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2537 bool is_during_mark = mark_in_progress(); 2538 2539 if (is_initial_mark) { 2540 return InitialMark; 2541 } else if (is_during_mark) { 2542 return DuringMark; 2543 } else if (is_young) { 2544 return Normal; 2545 } else { 2546 return Mixed; 2547 } 2548 } 2549 2550 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) { 2551 assert_at_safepoint(true /* should_be_vm_thread */); 2552 GCCauseSetter gcs(this, cause); 2553 switch (cause) { 2554 case GCCause::_heap_inspection: 2555 case GCCause::_heap_dump: { 2556 HandleMark hm; 2557 do_full_collection(false); // don't clear all soft refs 2558 break; 2559 } 2560 default: // XXX FIX ME 2561 ShouldNotReachHere(); // Unexpected use of this function 2562 } 2563 } 2564 2565 void G1CollectedHeap::collect(GCCause::Cause cause) { 2566 assert_heap_not_locked(); 2567 2568 unsigned int gc_count_before; 2569 unsigned int old_marking_count_before; 2570 bool retry_gc; 2571 2572 do { 2573 retry_gc = false; 2574 2575 { 2576 MutexLocker ml(Heap_lock); 2577 2578 // Read the GC count while holding the Heap_lock 2579 gc_count_before = total_collections(); 2580 old_marking_count_before = _old_marking_cycles_started; 2581 } 2582 2583 if (should_do_concurrent_full_gc(cause)) { 2584 // Schedule an initial-mark evacuation pause that will start a 2585 // concurrent cycle. We're setting word_size to 0 which means that 2586 // we are not requesting a post-GC allocation. 2587 VM_G1IncCollectionPause op(gc_count_before, 2588 0, /* word_size */ 2589 true, /* should_initiate_conc_mark */ 2590 g1_policy()->max_pause_time_ms(), 2591 cause); 2592 2593 VMThread::execute(&op); 2594 if (!op.pause_succeeded()) { 2595 if (old_marking_count_before == _old_marking_cycles_started) { 2596 retry_gc = op.should_retry_gc(); 2597 } else { 2598 // A Full GC happened while we were trying to schedule the 2599 // initial-mark GC. No point in starting a new cycle given 2600 // that the whole heap was collected anyway. 2601 } 2602 2603 if (retry_gc) { 2604 if (GC_locker::is_active_and_needs_gc()) { 2605 GC_locker::stall_until_clear(); 2606 } 2607 } 2608 } 2609 } else { 2610 if (cause == GCCause::_gc_locker 2611 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2612 2613 // Schedule a standard evacuation pause. We're setting word_size 2614 // to 0 which means that we are not requesting a post-GC allocation. 2615 VM_G1IncCollectionPause op(gc_count_before, 2616 0, /* word_size */ 2617 false, /* should_initiate_conc_mark */ 2618 g1_policy()->max_pause_time_ms(), 2619 cause); 2620 VMThread::execute(&op); 2621 } else { 2622 // Schedule a Full GC. 2623 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause); 2624 VMThread::execute(&op); 2625 } 2626 } 2627 } while (retry_gc); 2628 } 2629 2630 bool G1CollectedHeap::is_in(const void* p) const { 2631 if (_g1_committed.contains(p)) { 2632 // Given that we know that p is in the committed space, 2633 // heap_region_containing_raw() should successfully 2634 // return the containing region. 2635 HeapRegion* hr = heap_region_containing_raw(p); 2636 return hr->is_in(p); 2637 } else { 2638 return _perm_gen->as_gen()->is_in(p); 2639 } 2640 } 2641 2642 // Iteration functions. 2643 2644 // Iterates an OopClosure over all ref-containing fields of objects 2645 // within a HeapRegion. 2646 2647 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2648 MemRegion _mr; 2649 OopClosure* _cl; 2650 public: 2651 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl) 2652 : _mr(mr), _cl(cl) {} 2653 bool doHeapRegion(HeapRegion* r) { 2654 if (!r->continuesHumongous()) { 2655 r->oop_iterate(_cl); 2656 } 2657 return false; 2658 } 2659 }; 2660 2661 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) { 2662 IterateOopClosureRegionClosure blk(_g1_committed, cl); 2663 heap_region_iterate(&blk); 2664 if (do_perm) { 2665 perm_gen()->oop_iterate(cl); 2666 } 2667 } 2668 2669 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) { 2670 IterateOopClosureRegionClosure blk(mr, cl); 2671 heap_region_iterate(&blk); 2672 if (do_perm) { 2673 perm_gen()->oop_iterate(cl); 2674 } 2675 } 2676 2677 // Iterates an ObjectClosure over all objects within a HeapRegion. 2678 2679 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2680 ObjectClosure* _cl; 2681 public: 2682 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2683 bool doHeapRegion(HeapRegion* r) { 2684 if (! r->continuesHumongous()) { 2685 r->object_iterate(_cl); 2686 } 2687 return false; 2688 } 2689 }; 2690 2691 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) { 2692 IterateObjectClosureRegionClosure blk(cl); 2693 heap_region_iterate(&blk); 2694 if (do_perm) { 2695 perm_gen()->object_iterate(cl); 2696 } 2697 } 2698 2699 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) { 2700 // FIXME: is this right? 2701 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap"); 2702 } 2703 2704 // Calls a SpaceClosure on a HeapRegion. 2705 2706 class SpaceClosureRegionClosure: public HeapRegionClosure { 2707 SpaceClosure* _cl; 2708 public: 2709 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} 2710 bool doHeapRegion(HeapRegion* r) { 2711 _cl->do_space(r); 2712 return false; 2713 } 2714 }; 2715 2716 void G1CollectedHeap::space_iterate(SpaceClosure* cl) { 2717 SpaceClosureRegionClosure blk(cl); 2718 heap_region_iterate(&blk); 2719 } 2720 2721 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2722 _hrs.iterate(cl); 2723 } 2724 2725 void 2726 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl, 2727 uint worker_id, 2728 uint no_of_par_workers, 2729 jint claim_value) { 2730 const uint regions = n_regions(); 2731 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 2732 no_of_par_workers : 2733 1); 2734 assert(UseDynamicNumberOfGCThreads || 2735 no_of_par_workers == workers()->total_workers(), 2736 "Non dynamic should use fixed number of workers"); 2737 // try to spread out the starting points of the workers 2738 const HeapRegion* start_hr = 2739 start_region_for_worker(worker_id, no_of_par_workers); 2740 const uint start_index = start_hr->hrs_index(); 2741 2742 // each worker will actually look at all regions 2743 for (uint count = 0; count < regions; ++count) { 2744 const uint index = (start_index + count) % regions; 2745 assert(0 <= index && index < regions, "sanity"); 2746 HeapRegion* r = region_at(index); 2747 // we'll ignore "continues humongous" regions (we'll process them 2748 // when we come across their corresponding "start humongous" 2749 // region) and regions already claimed 2750 if (r->claim_value() == claim_value || r->continuesHumongous()) { 2751 continue; 2752 } 2753 // OK, try to claim it 2754 if (r->claimHeapRegion(claim_value)) { 2755 // success! 2756 assert(!r->continuesHumongous(), "sanity"); 2757 if (r->startsHumongous()) { 2758 // If the region is "starts humongous" we'll iterate over its 2759 // "continues humongous" first; in fact we'll do them 2760 // first. The order is important. In on case, calling the 2761 // closure on the "starts humongous" region might de-allocate 2762 // and clear all its "continues humongous" regions and, as a 2763 // result, we might end up processing them twice. So, we'll do 2764 // them first (notice: most closures will ignore them anyway) and 2765 // then we'll do the "starts humongous" region. 2766 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) { 2767 HeapRegion* chr = region_at(ch_index); 2768 2769 // if the region has already been claimed or it's not 2770 // "continues humongous" we're done 2771 if (chr->claim_value() == claim_value || 2772 !chr->continuesHumongous()) { 2773 break; 2774 } 2775 2776 // Noone should have claimed it directly. We can given 2777 // that we claimed its "starts humongous" region. 2778 assert(chr->claim_value() != claim_value, "sanity"); 2779 assert(chr->humongous_start_region() == r, "sanity"); 2780 2781 if (chr->claimHeapRegion(claim_value)) { 2782 // we should always be able to claim it; noone else should 2783 // be trying to claim this region 2784 2785 bool res2 = cl->doHeapRegion(chr); 2786 assert(!res2, "Should not abort"); 2787 2788 // Right now, this holds (i.e., no closure that actually 2789 // does something with "continues humongous" regions 2790 // clears them). We might have to weaken it in the future, 2791 // but let's leave these two asserts here for extra safety. 2792 assert(chr->continuesHumongous(), "should still be the case"); 2793 assert(chr->humongous_start_region() == r, "sanity"); 2794 } else { 2795 guarantee(false, "we should not reach here"); 2796 } 2797 } 2798 } 2799 2800 assert(!r->continuesHumongous(), "sanity"); 2801 bool res = cl->doHeapRegion(r); 2802 assert(!res, "Should not abort"); 2803 } 2804 } 2805 } 2806 2807 class ResetClaimValuesClosure: public HeapRegionClosure { 2808 public: 2809 bool doHeapRegion(HeapRegion* r) { 2810 r->set_claim_value(HeapRegion::InitialClaimValue); 2811 return false; 2812 } 2813 }; 2814 2815 void G1CollectedHeap::reset_heap_region_claim_values() { 2816 ResetClaimValuesClosure blk; 2817 heap_region_iterate(&blk); 2818 } 2819 2820 void G1CollectedHeap::reset_cset_heap_region_claim_values() { 2821 ResetClaimValuesClosure blk; 2822 collection_set_iterate(&blk); 2823 } 2824 2825 #ifdef ASSERT 2826 // This checks whether all regions in the heap have the correct claim 2827 // value. I also piggy-backed on this a check to ensure that the 2828 // humongous_start_region() information on "continues humongous" 2829 // regions is correct. 2830 2831 class CheckClaimValuesClosure : public HeapRegionClosure { 2832 private: 2833 jint _claim_value; 2834 uint _failures; 2835 HeapRegion* _sh_region; 2836 2837 public: 2838 CheckClaimValuesClosure(jint claim_value) : 2839 _claim_value(claim_value), _failures(0), _sh_region(NULL) { } 2840 bool doHeapRegion(HeapRegion* r) { 2841 if (r->claim_value() != _claim_value) { 2842 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2843 "claim value = %d, should be %d", 2844 HR_FORMAT_PARAMS(r), 2845 r->claim_value(), _claim_value); 2846 ++_failures; 2847 } 2848 if (!r->isHumongous()) { 2849 _sh_region = NULL; 2850 } else if (r->startsHumongous()) { 2851 _sh_region = r; 2852 } else if (r->continuesHumongous()) { 2853 if (r->humongous_start_region() != _sh_region) { 2854 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2855 "HS = "PTR_FORMAT", should be "PTR_FORMAT, 2856 HR_FORMAT_PARAMS(r), 2857 r->humongous_start_region(), 2858 _sh_region); 2859 ++_failures; 2860 } 2861 } 2862 return false; 2863 } 2864 uint failures() { return _failures; } 2865 }; 2866 2867 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) { 2868 CheckClaimValuesClosure cl(claim_value); 2869 heap_region_iterate(&cl); 2870 return cl.failures() == 0; 2871 } 2872 2873 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure { 2874 private: 2875 jint _claim_value; 2876 uint _failures; 2877 2878 public: 2879 CheckClaimValuesInCSetHRClosure(jint claim_value) : 2880 _claim_value(claim_value), _failures(0) { } 2881 2882 uint failures() { return _failures; } 2883 2884 bool doHeapRegion(HeapRegion* hr) { 2885 assert(hr->in_collection_set(), "how?"); 2886 assert(!hr->isHumongous(), "H-region in CSet"); 2887 if (hr->claim_value() != _claim_value) { 2888 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", " 2889 "claim value = %d, should be %d", 2890 HR_FORMAT_PARAMS(hr), 2891 hr->claim_value(), _claim_value); 2892 _failures += 1; 2893 } 2894 return false; 2895 } 2896 }; 2897 2898 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) { 2899 CheckClaimValuesInCSetHRClosure cl(claim_value); 2900 collection_set_iterate(&cl); 2901 return cl.failures() == 0; 2902 } 2903 #endif // ASSERT 2904 2905 // Clear the cached CSet starting regions and (more importantly) 2906 // the time stamps. Called when we reset the GC time stamp. 2907 void G1CollectedHeap::clear_cset_start_regions() { 2908 assert(_worker_cset_start_region != NULL, "sanity"); 2909 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2910 2911 int n_queues = MAX2((int)ParallelGCThreads, 1); 2912 for (int i = 0; i < n_queues; i++) { 2913 _worker_cset_start_region[i] = NULL; 2914 _worker_cset_start_region_time_stamp[i] = 0; 2915 } 2916 } 2917 2918 // Given the id of a worker, obtain or calculate a suitable 2919 // starting region for iterating over the current collection set. 2920 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) { 2921 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2922 2923 HeapRegion* result = NULL; 2924 unsigned gc_time_stamp = get_gc_time_stamp(); 2925 2926 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2927 // Cached starting region for current worker was set 2928 // during the current pause - so it's valid. 2929 // Note: the cached starting heap region may be NULL 2930 // (when the collection set is empty). 2931 result = _worker_cset_start_region[worker_i]; 2932 assert(result == NULL || result->in_collection_set(), "sanity"); 2933 return result; 2934 } 2935 2936 // The cached entry was not valid so let's calculate 2937 // a suitable starting heap region for this worker. 2938 2939 // We want the parallel threads to start their collection 2940 // set iteration at different collection set regions to 2941 // avoid contention. 2942 // If we have: 2943 // n collection set regions 2944 // p threads 2945 // Then thread t will start at region floor ((t * n) / p) 2946 2947 result = g1_policy()->collection_set(); 2948 if (G1CollectedHeap::use_parallel_gc_threads()) { 2949 uint cs_size = g1_policy()->cset_region_length(); 2950 uint active_workers = workers()->active_workers(); 2951 assert(UseDynamicNumberOfGCThreads || 2952 active_workers == workers()->total_workers(), 2953 "Unless dynamic should use total workers"); 2954 2955 uint end_ind = (cs_size * worker_i) / active_workers; 2956 uint start_ind = 0; 2957 2958 if (worker_i > 0 && 2959 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2960 // Previous workers starting region is valid 2961 // so let's iterate from there 2962 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2963 result = _worker_cset_start_region[worker_i - 1]; 2964 } 2965 2966 for (uint i = start_ind; i < end_ind; i++) { 2967 result = result->next_in_collection_set(); 2968 } 2969 } 2970 2971 // Note: the calculated starting heap region may be NULL 2972 // (when the collection set is empty). 2973 assert(result == NULL || result->in_collection_set(), "sanity"); 2974 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2975 "should be updated only once per pause"); 2976 _worker_cset_start_region[worker_i] = result; 2977 OrderAccess::storestore(); 2978 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2979 return result; 2980 } 2981 2982 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i, 2983 uint no_of_par_workers) { 2984 uint worker_num = 2985 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U; 2986 assert(UseDynamicNumberOfGCThreads || 2987 no_of_par_workers == workers()->total_workers(), 2988 "Non dynamic should use fixed number of workers"); 2989 const uint start_index = n_regions() * worker_i / worker_num; 2990 return region_at(start_index); 2991 } 2992 2993 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2994 HeapRegion* r = g1_policy()->collection_set(); 2995 while (r != NULL) { 2996 HeapRegion* next = r->next_in_collection_set(); 2997 if (cl->doHeapRegion(r)) { 2998 cl->incomplete(); 2999 return; 3000 } 3001 r = next; 3002 } 3003 } 3004 3005 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 3006 HeapRegionClosure *cl) { 3007 if (r == NULL) { 3008 // The CSet is empty so there's nothing to do. 3009 return; 3010 } 3011 3012 assert(r->in_collection_set(), 3013 "Start region must be a member of the collection set."); 3014 HeapRegion* cur = r; 3015 while (cur != NULL) { 3016 HeapRegion* next = cur->next_in_collection_set(); 3017 if (cl->doHeapRegion(cur) && false) { 3018 cl->incomplete(); 3019 return; 3020 } 3021 cur = next; 3022 } 3023 cur = g1_policy()->collection_set(); 3024 while (cur != r) { 3025 HeapRegion* next = cur->next_in_collection_set(); 3026 if (cl->doHeapRegion(cur) && false) { 3027 cl->incomplete(); 3028 return; 3029 } 3030 cur = next; 3031 } 3032 } 3033 3034 CompactibleSpace* G1CollectedHeap::first_compactible_space() { 3035 return n_regions() > 0 ? region_at(0) : NULL; 3036 } 3037 3038 3039 Space* G1CollectedHeap::space_containing(const void* addr) const { 3040 Space* res = heap_region_containing(addr); 3041 if (res == NULL) 3042 res = perm_gen()->space_containing(addr); 3043 return res; 3044 } 3045 3046 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 3047 Space* sp = space_containing(addr); 3048 if (sp != NULL) { 3049 return sp->block_start(addr); 3050 } 3051 return NULL; 3052 } 3053 3054 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 3055 Space* sp = space_containing(addr); 3056 assert(sp != NULL, "block_size of address outside of heap"); 3057 return sp->block_size(addr); 3058 } 3059 3060 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 3061 Space* sp = space_containing(addr); 3062 return sp->block_is_obj(addr); 3063 } 3064 3065 bool G1CollectedHeap::supports_tlab_allocation() const { 3066 return true; 3067 } 3068 3069 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 3070 return HeapRegion::GrainBytes; 3071 } 3072 3073 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 3074 // Return the remaining space in the cur alloc region, but not less than 3075 // the min TLAB size. 3076 3077 // Also, this value can be at most the humongous object threshold, 3078 // since we can't allow tlabs to grow big enough to accommodate 3079 // humongous objects. 3080 3081 HeapRegion* hr = _mutator_alloc_region.get(); 3082 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize; 3083 if (hr == NULL) { 3084 return max_tlab_size; 3085 } else { 3086 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size); 3087 } 3088 } 3089 3090 size_t G1CollectedHeap::max_capacity() const { 3091 return _g1_reserved.byte_size(); 3092 } 3093 3094 jlong G1CollectedHeap::millis_since_last_gc() { 3095 // assert(false, "NYI"); 3096 return 0; 3097 } 3098 3099 void G1CollectedHeap::prepare_for_verify() { 3100 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 3101 ensure_parsability(false); 3102 } 3103 g1_rem_set()->prepare_for_verify(); 3104 } 3105 3106 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 3107 VerifyOption vo) { 3108 switch (vo) { 3109 case VerifyOption_G1UsePrevMarking: 3110 return hr->obj_allocated_since_prev_marking(obj); 3111 case VerifyOption_G1UseNextMarking: 3112 return hr->obj_allocated_since_next_marking(obj); 3113 case VerifyOption_G1UseMarkWord: 3114 return false; 3115 default: 3116 ShouldNotReachHere(); 3117 } 3118 return false; // keep some compilers happy 3119 } 3120 3121 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 3122 switch (vo) { 3123 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 3124 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 3125 case VerifyOption_G1UseMarkWord: return NULL; 3126 default: ShouldNotReachHere(); 3127 } 3128 return NULL; // keep some compilers happy 3129 } 3130 3131 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 3132 switch (vo) { 3133 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 3134 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 3135 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 3136 default: ShouldNotReachHere(); 3137 } 3138 return false; // keep some compilers happy 3139 } 3140 3141 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 3142 switch (vo) { 3143 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 3144 case VerifyOption_G1UseNextMarking: return "NTAMS"; 3145 case VerifyOption_G1UseMarkWord: return "NONE"; 3146 default: ShouldNotReachHere(); 3147 } 3148 return NULL; // keep some compilers happy 3149 } 3150 3151 class VerifyLivenessOopClosure: public OopClosure { 3152 G1CollectedHeap* _g1h; 3153 VerifyOption _vo; 3154 public: 3155 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 3156 _g1h(g1h), _vo(vo) 3157 { } 3158 void do_oop(narrowOop *p) { do_oop_work(p); } 3159 void do_oop( oop *p) { do_oop_work(p); } 3160 3161 template <class T> void do_oop_work(T *p) { 3162 oop obj = oopDesc::load_decode_heap_oop(p); 3163 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 3164 "Dead object referenced by a not dead object"); 3165 } 3166 }; 3167 3168 class VerifyObjsInRegionClosure: public ObjectClosure { 3169 private: 3170 G1CollectedHeap* _g1h; 3171 size_t _live_bytes; 3172 HeapRegion *_hr; 3173 VerifyOption _vo; 3174 public: 3175 // _vo == UsePrevMarking -> use "prev" marking information, 3176 // _vo == UseNextMarking -> use "next" marking information, 3177 // _vo == UseMarkWord -> use mark word from object header. 3178 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 3179 : _live_bytes(0), _hr(hr), _vo(vo) { 3180 _g1h = G1CollectedHeap::heap(); 3181 } 3182 void do_object(oop o) { 3183 VerifyLivenessOopClosure isLive(_g1h, _vo); 3184 assert(o != NULL, "Huh?"); 3185 if (!_g1h->is_obj_dead_cond(o, _vo)) { 3186 // If the object is alive according to the mark word, 3187 // then verify that the marking information agrees. 3188 // Note we can't verify the contra-positive of the 3189 // above: if the object is dead (according to the mark 3190 // word), it may not be marked, or may have been marked 3191 // but has since became dead, or may have been allocated 3192 // since the last marking. 3193 if (_vo == VerifyOption_G1UseMarkWord) { 3194 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 3195 } 3196 3197 o->oop_iterate(&isLive); 3198 if (!_hr->obj_allocated_since_prev_marking(o)) { 3199 size_t obj_size = o->size(); // Make sure we don't overflow 3200 _live_bytes += (obj_size * HeapWordSize); 3201 } 3202 } 3203 } 3204 size_t live_bytes() { return _live_bytes; } 3205 }; 3206 3207 class PrintObjsInRegionClosure : public ObjectClosure { 3208 HeapRegion *_hr; 3209 G1CollectedHeap *_g1; 3210 public: 3211 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 3212 _g1 = G1CollectedHeap::heap(); 3213 }; 3214 3215 void do_object(oop o) { 3216 if (o != NULL) { 3217 HeapWord *start = (HeapWord *) o; 3218 size_t word_sz = o->size(); 3219 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 3220 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 3221 (void*) o, word_sz, 3222 _g1->isMarkedPrev(o), 3223 _g1->isMarkedNext(o), 3224 _hr->obj_allocated_since_prev_marking(o)); 3225 HeapWord *end = start + word_sz; 3226 HeapWord *cur; 3227 int *val; 3228 for (cur = start; cur < end; cur++) { 3229 val = (int *) cur; 3230 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val); 3231 } 3232 } 3233 } 3234 }; 3235 3236 class VerifyRegionClosure: public HeapRegionClosure { 3237 private: 3238 bool _par; 3239 VerifyOption _vo; 3240 bool _failures; 3241 public: 3242 // _vo == UsePrevMarking -> use "prev" marking information, 3243 // _vo == UseNextMarking -> use "next" marking information, 3244 // _vo == UseMarkWord -> use mark word from object header. 3245 VerifyRegionClosure(bool par, VerifyOption vo) 3246 : _par(par), 3247 _vo(vo), 3248 _failures(false) {} 3249 3250 bool failures() { 3251 return _failures; 3252 } 3253 3254 bool doHeapRegion(HeapRegion* r) { 3255 if (!r->continuesHumongous()) { 3256 bool failures = false; 3257 r->verify(_vo, &failures); 3258 if (failures) { 3259 _failures = true; 3260 } else { 3261 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3262 r->object_iterate(¬_dead_yet_cl); 3263 if (_vo != VerifyOption_G1UseNextMarking) { 3264 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3265 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 3266 "max_live_bytes "SIZE_FORMAT" " 3267 "< calculated "SIZE_FORMAT, 3268 r->bottom(), r->end(), 3269 r->max_live_bytes(), 3270 not_dead_yet_cl.live_bytes()); 3271 _failures = true; 3272 } 3273 } else { 3274 // When vo == UseNextMarking we cannot currently do a sanity 3275 // check on the live bytes as the calculation has not been 3276 // finalized yet. 3277 } 3278 } 3279 } 3280 return false; // stop the region iteration if we hit a failure 3281 } 3282 }; 3283 3284 class VerifyRootsClosure: public OopsInGenClosure { 3285 private: 3286 G1CollectedHeap* _g1h; 3287 VerifyOption _vo; 3288 bool _failures; 3289 public: 3290 // _vo == UsePrevMarking -> use "prev" marking information, 3291 // _vo == UseNextMarking -> use "next" marking information, 3292 // _vo == UseMarkWord -> use mark word from object header. 3293 VerifyRootsClosure(VerifyOption vo) : 3294 _g1h(G1CollectedHeap::heap()), 3295 _vo(vo), 3296 _failures(false) { } 3297 3298 bool failures() { return _failures; } 3299 3300 template <class T> void do_oop_nv(T* p) { 3301 T heap_oop = oopDesc::load_heap_oop(p); 3302 if (!oopDesc::is_null(heap_oop)) { 3303 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3304 if (_g1h->is_obj_dead_cond(obj, _vo)) { 3305 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 3306 "points to dead obj "PTR_FORMAT, p, (void*) obj); 3307 if (_vo == VerifyOption_G1UseMarkWord) { 3308 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 3309 } 3310 obj->print_on(gclog_or_tty); 3311 _failures = true; 3312 } 3313 } 3314 } 3315 3316 void do_oop(oop* p) { do_oop_nv(p); } 3317 void do_oop(narrowOop* p) { do_oop_nv(p); } 3318 }; 3319 3320 // This is the task used for parallel heap verification. 3321 3322 class G1ParVerifyTask: public AbstractGangTask { 3323 private: 3324 G1CollectedHeap* _g1h; 3325 VerifyOption _vo; 3326 bool _failures; 3327 3328 public: 3329 // _vo == UsePrevMarking -> use "prev" marking information, 3330 // _vo == UseNextMarking -> use "next" marking information, 3331 // _vo == UseMarkWord -> use mark word from object header. 3332 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3333 AbstractGangTask("Parallel verify task"), 3334 _g1h(g1h), 3335 _vo(vo), 3336 _failures(false) { } 3337 3338 bool failures() { 3339 return _failures; 3340 } 3341 3342 void work(uint worker_id) { 3343 HandleMark hm; 3344 VerifyRegionClosure blk(true, _vo); 3345 _g1h->heap_region_par_iterate_chunked(&blk, worker_id, 3346 _g1h->workers()->active_workers(), 3347 HeapRegion::ParVerifyClaimValue); 3348 if (blk.failures()) { 3349 _failures = true; 3350 } 3351 } 3352 }; 3353 3354 void G1CollectedHeap::verify(bool silent) { 3355 verify(silent, VerifyOption_G1UsePrevMarking); 3356 } 3357 3358 void G1CollectedHeap::verify(bool silent, 3359 VerifyOption vo) { 3360 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 3361 if (!silent) { gclog_or_tty->print("Roots (excluding permgen) "); } 3362 VerifyRootsClosure rootsCl(vo); 3363 3364 assert(Thread::current()->is_VM_thread(), 3365 "Expected to be executed serially by the VM thread at this point"); 3366 3367 CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false); 3368 3369 // We apply the relevant closures to all the oops in the 3370 // system dictionary, the string table and the code cache. 3371 const int so = SO_AllClasses | SO_Strings | SO_CodeCache; 3372 3373 process_strong_roots(true, // activate StrongRootsScope 3374 true, // we set "collecting perm gen" to true, 3375 // so we don't reset the dirty cards in the perm gen. 3376 ScanningOption(so), // roots scanning options 3377 &rootsCl, 3378 &blobsCl, 3379 &rootsCl); 3380 3381 // If we're verifying after the marking phase of a Full GC then we can't 3382 // treat the perm gen as roots into the G1 heap. Some of the objects in 3383 // the perm gen may be dead and hence not marked. If one of these dead 3384 // objects is considered to be a root then we may end up with a false 3385 // "Root location <x> points to dead ob <y>" failure. 3386 if (vo != VerifyOption_G1UseMarkWord) { 3387 // Since we used "collecting_perm_gen" == true above, we will not have 3388 // checked the refs from perm into the G1-collected heap. We check those 3389 // references explicitly below. Whether the relevant cards are dirty 3390 // is checked further below in the rem set verification. 3391 if (!silent) { gclog_or_tty->print("Permgen roots "); } 3392 perm_gen()->oop_iterate(&rootsCl); 3393 } 3394 bool failures = rootsCl.failures(); 3395 3396 if (vo != VerifyOption_G1UseMarkWord) { 3397 // If we're verifying during a full GC then the region sets 3398 // will have been torn down at the start of the GC. Therefore 3399 // verifying the region sets will fail. So we only verify 3400 // the region sets when not in a full GC. 3401 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3402 verify_region_sets(); 3403 } 3404 3405 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3406 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3407 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3408 "sanity check"); 3409 3410 G1ParVerifyTask task(this, vo); 3411 assert(UseDynamicNumberOfGCThreads || 3412 workers()->active_workers() == workers()->total_workers(), 3413 "If not dynamic should be using all the workers"); 3414 int n_workers = workers()->active_workers(); 3415 set_par_threads(n_workers); 3416 workers()->run_task(&task); 3417 set_par_threads(0); 3418 if (task.failures()) { 3419 failures = true; 3420 } 3421 3422 // Checks that the expected amount of parallel work was done. 3423 // The implication is that n_workers is > 0. 3424 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue), 3425 "sanity check"); 3426 3427 reset_heap_region_claim_values(); 3428 3429 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3430 "sanity check"); 3431 } else { 3432 VerifyRegionClosure blk(false, vo); 3433 heap_region_iterate(&blk); 3434 if (blk.failures()) { 3435 failures = true; 3436 } 3437 } 3438 if (!silent) gclog_or_tty->print("RemSet "); 3439 rem_set()->verify(); 3440 3441 if (failures) { 3442 gclog_or_tty->print_cr("Heap:"); 3443 // It helps to have the per-region information in the output to 3444 // help us track down what went wrong. This is why we call 3445 // print_extended_on() instead of print_on(). 3446 print_extended_on(gclog_or_tty); 3447 gclog_or_tty->print_cr(""); 3448 #ifndef PRODUCT 3449 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 3450 concurrent_mark()->print_reachable("at-verification-failure", 3451 vo, false /* all */); 3452 } 3453 #endif 3454 gclog_or_tty->flush(); 3455 } 3456 guarantee(!failures, "there should not have been any failures"); 3457 } else { 3458 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) "); 3459 } 3460 } 3461 3462 class PrintRegionClosure: public HeapRegionClosure { 3463 outputStream* _st; 3464 public: 3465 PrintRegionClosure(outputStream* st) : _st(st) {} 3466 bool doHeapRegion(HeapRegion* r) { 3467 r->print_on(_st); 3468 return false; 3469 } 3470 }; 3471 3472 void G1CollectedHeap::print_on(outputStream* st) const { 3473 st->print(" %-20s", "garbage-first heap"); 3474 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3475 capacity()/K, used_unlocked()/K); 3476 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3477 _g1_storage.low_boundary(), 3478 _g1_storage.high(), 3479 _g1_storage.high_boundary()); 3480 st->cr(); 3481 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3482 uint young_regions = _young_list->length(); 3483 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3484 (size_t) young_regions * HeapRegion::GrainBytes / K); 3485 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3486 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3487 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3488 st->cr(); 3489 perm()->as_gen()->print_on(st); 3490 } 3491 3492 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3493 print_on(st); 3494 3495 // Print the per-region information. 3496 st->cr(); 3497 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3498 "HS=humongous(starts), HC=humongous(continues), " 3499 "CS=collection set, F=free, TS=gc time stamp, " 3500 "PTAMS=previous top-at-mark-start, " 3501 "NTAMS=next top-at-mark-start)"); 3502 PrintRegionClosure blk(st); 3503 heap_region_iterate(&blk); 3504 } 3505 3506 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3507 if (G1CollectedHeap::use_parallel_gc_threads()) { 3508 workers()->print_worker_threads_on(st); 3509 } 3510 _cmThread->print_on(st); 3511 st->cr(); 3512 _cm->print_worker_threads_on(st); 3513 _cg1r->print_worker_threads_on(st); 3514 st->cr(); 3515 } 3516 3517 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3518 if (G1CollectedHeap::use_parallel_gc_threads()) { 3519 workers()->threads_do(tc); 3520 } 3521 tc->do_thread(_cmThread); 3522 _cg1r->threads_do(tc); 3523 } 3524 3525 void G1CollectedHeap::print_tracing_info() const { 3526 // We'll overload this to mean "trace GC pause statistics." 3527 if (TraceGen0Time || TraceGen1Time) { 3528 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3529 // to that. 3530 g1_policy()->print_tracing_info(); 3531 } 3532 if (G1SummarizeRSetStats) { 3533 g1_rem_set()->print_summary_info(); 3534 } 3535 if (G1SummarizeConcMark) { 3536 concurrent_mark()->print_summary_info(); 3537 } 3538 g1_policy()->print_yg_surv_rate_info(); 3539 SpecializationStats::print(); 3540 } 3541 3542 #ifndef PRODUCT 3543 // Helpful for debugging RSet issues. 3544 3545 class PrintRSetsClosure : public HeapRegionClosure { 3546 private: 3547 const char* _msg; 3548 size_t _occupied_sum; 3549 3550 public: 3551 bool doHeapRegion(HeapRegion* r) { 3552 HeapRegionRemSet* hrrs = r->rem_set(); 3553 size_t occupied = hrrs->occupied(); 3554 _occupied_sum += occupied; 3555 3556 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3557 HR_FORMAT_PARAMS(r)); 3558 if (occupied == 0) { 3559 gclog_or_tty->print_cr(" RSet is empty"); 3560 } else { 3561 hrrs->print(); 3562 } 3563 gclog_or_tty->print_cr("----------"); 3564 return false; 3565 } 3566 3567 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3568 gclog_or_tty->cr(); 3569 gclog_or_tty->print_cr("========================================"); 3570 gclog_or_tty->print_cr(msg); 3571 gclog_or_tty->cr(); 3572 } 3573 3574 ~PrintRSetsClosure() { 3575 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3576 gclog_or_tty->print_cr("========================================"); 3577 gclog_or_tty->cr(); 3578 } 3579 }; 3580 3581 void G1CollectedHeap::print_cset_rsets() { 3582 PrintRSetsClosure cl("Printing CSet RSets"); 3583 collection_set_iterate(&cl); 3584 } 3585 3586 void G1CollectedHeap::print_all_rsets() { 3587 PrintRSetsClosure cl("Printing All RSets");; 3588 heap_region_iterate(&cl); 3589 } 3590 #endif // PRODUCT 3591 3592 G1CollectedHeap* G1CollectedHeap::heap() { 3593 assert(_sh->kind() == CollectedHeap::G1CollectedHeap, 3594 "not a garbage-first heap"); 3595 return _g1h; 3596 } 3597 3598 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3599 // always_do_update_barrier = false; 3600 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3601 // Call allocation profiler 3602 AllocationProfiler::iterate_since_last_gc(); 3603 // Fill TLAB's and such 3604 ensure_parsability(true); 3605 } 3606 3607 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) { 3608 // FIXME: what is this about? 3609 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3610 // is set. 3611 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3612 "derived pointer present")); 3613 // always_do_update_barrier = true; 3614 3615 // We have just completed a GC. Update the soft reference 3616 // policy with the new heap occupancy 3617 Universe::update_heap_info_at_gc(); 3618 } 3619 3620 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3621 unsigned int gc_count_before, 3622 bool* succeeded) { 3623 assert_heap_not_locked_and_not_at_safepoint(); 3624 g1_policy()->record_stop_world_start(); 3625 VM_G1IncCollectionPause op(gc_count_before, 3626 word_size, 3627 false, /* should_initiate_conc_mark */ 3628 g1_policy()->max_pause_time_ms(), 3629 GCCause::_g1_inc_collection_pause); 3630 VMThread::execute(&op); 3631 3632 HeapWord* result = op.result(); 3633 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3634 assert(result == NULL || ret_succeeded, 3635 "the result should be NULL if the VM did not succeed"); 3636 *succeeded = ret_succeeded; 3637 3638 assert_heap_not_locked(); 3639 return result; 3640 } 3641 3642 void 3643 G1CollectedHeap::doConcurrentMark() { 3644 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3645 if (!_cmThread->in_progress()) { 3646 _cmThread->set_started(); 3647 CGC_lock->notify(); 3648 } 3649 } 3650 3651 size_t G1CollectedHeap::pending_card_num() { 3652 size_t extra_cards = 0; 3653 JavaThread *curr = Threads::first(); 3654 while (curr != NULL) { 3655 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3656 extra_cards += dcq.size(); 3657 curr = curr->next(); 3658 } 3659 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3660 size_t buffer_size = dcqs.buffer_size(); 3661 size_t buffer_num = dcqs.completed_buffers_num(); 3662 3663 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3664 // in bytes - not the number of 'entries'. We need to convert 3665 // into a number of cards. 3666 return (buffer_size * buffer_num + extra_cards) / oopSize; 3667 } 3668 3669 size_t G1CollectedHeap::cards_scanned() { 3670 return g1_rem_set()->cardsScanned(); 3671 } 3672 3673 void 3674 G1CollectedHeap::setup_surviving_young_words() { 3675 assert(_surviving_young_words == NULL, "pre-condition"); 3676 uint array_length = g1_policy()->young_cset_region_length(); 3677 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3678 if (_surviving_young_words == NULL) { 3679 vm_exit_out_of_memory(sizeof(size_t) * array_length, 3680 "Not enough space for young surv words summary."); 3681 } 3682 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3683 #ifdef ASSERT 3684 for (uint i = 0; i < array_length; ++i) { 3685 assert( _surviving_young_words[i] == 0, "memset above" ); 3686 } 3687 #endif // !ASSERT 3688 } 3689 3690 void 3691 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3692 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3693 uint array_length = g1_policy()->young_cset_region_length(); 3694 for (uint i = 0; i < array_length; ++i) { 3695 _surviving_young_words[i] += surv_young_words[i]; 3696 } 3697 } 3698 3699 void 3700 G1CollectedHeap::cleanup_surviving_young_words() { 3701 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3702 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC); 3703 _surviving_young_words = NULL; 3704 } 3705 3706 #ifdef ASSERT 3707 class VerifyCSetClosure: public HeapRegionClosure { 3708 public: 3709 bool doHeapRegion(HeapRegion* hr) { 3710 // Here we check that the CSet region's RSet is ready for parallel 3711 // iteration. The fields that we'll verify are only manipulated 3712 // when the region is part of a CSet and is collected. Afterwards, 3713 // we reset these fields when we clear the region's RSet (when the 3714 // region is freed) so they are ready when the region is 3715 // re-allocated. The only exception to this is if there's an 3716 // evacuation failure and instead of freeing the region we leave 3717 // it in the heap. In that case, we reset these fields during 3718 // evacuation failure handling. 3719 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3720 3721 // Here's a good place to add any other checks we'd like to 3722 // perform on CSet regions. 3723 return false; 3724 } 3725 }; 3726 #endif // ASSERT 3727 3728 #if TASKQUEUE_STATS 3729 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3730 st->print_raw_cr("GC Task Stats"); 3731 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3732 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3733 } 3734 3735 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3736 print_taskqueue_stats_hdr(st); 3737 3738 TaskQueueStats totals; 3739 const int n = workers() != NULL ? workers()->total_workers() : 1; 3740 for (int i = 0; i < n; ++i) { 3741 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3742 totals += task_queue(i)->stats; 3743 } 3744 st->print_raw("tot "); totals.print(st); st->cr(); 3745 3746 DEBUG_ONLY(totals.verify()); 3747 } 3748 3749 void G1CollectedHeap::reset_taskqueue_stats() { 3750 const int n = workers() != NULL ? workers()->total_workers() : 1; 3751 for (int i = 0; i < n; ++i) { 3752 task_queue(i)->stats.reset(); 3753 } 3754 } 3755 #endif // TASKQUEUE_STATS 3756 3757 void G1CollectedHeap::log_gc_header() { 3758 if (!G1Log::fine()) { 3759 return; 3760 } 3761 3762 gclog_or_tty->date_stamp(PrintGCDateStamps); 3763 gclog_or_tty->stamp(PrintGCTimeStamps); 3764 3765 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3766 .append(g1_policy()->gcs_are_young() ? " (young)" : " (mixed)") 3767 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3768 3769 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3770 } 3771 3772 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3773 if (!G1Log::fine()) { 3774 return; 3775 } 3776 3777 if (G1Log::finer()) { 3778 if (evacuation_failed()) { 3779 gclog_or_tty->print(" (to-space exhausted)"); 3780 } 3781 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3782 g1_policy()->phase_times()->note_gc_end(); 3783 g1_policy()->phase_times()->print(pause_time_sec); 3784 g1_policy()->print_detailed_heap_transition(); 3785 } else { 3786 if (evacuation_failed()) { 3787 gclog_or_tty->print("--"); 3788 } 3789 g1_policy()->print_heap_transition(); 3790 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3791 } 3792 gclog_or_tty->flush(); 3793 } 3794 3795 bool 3796 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3797 assert_at_safepoint(true /* should_be_vm_thread */); 3798 guarantee(!is_gc_active(), "collection is not reentrant"); 3799 3800 if (GC_locker::check_active_before_gc()) { 3801 return false; 3802 } 3803 3804 _gc_timer_stw->register_gc_start(os::elapsed_counter()); 3805 3806 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3807 3808 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3809 ResourceMark rm; 3810 3811 print_heap_before_gc(); 3812 trace_heap_before_gc(_gc_tracer_stw); 3813 3814 HRSPhaseSetter x(HRSPhaseEvacuation); 3815 verify_region_sets_optional(); 3816 verify_dirty_young_regions(); 3817 3818 // This call will decide whether this pause is an initial-mark 3819 // pause. If it is, during_initial_mark_pause() will return true 3820 // for the duration of this pause. 3821 g1_policy()->decide_on_conc_mark_initiation(); 3822 3823 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3824 assert(!g1_policy()->during_initial_mark_pause() || 3825 g1_policy()->gcs_are_young(), "sanity"); 3826 3827 // We also do not allow mixed GCs during marking. 3828 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3829 3830 // Record whether this pause is an initial mark. When the current 3831 // thread has completed its logging output and it's safe to signal 3832 // the CM thread, the flag's value in the policy has been reset. 3833 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3834 3835 // Inner scope for scope based logging, timers, and stats collection 3836 { 3837 EvacuationInfo evacuation_info; 3838 3839 if (g1_policy()->during_initial_mark_pause()) { 3840 // We are about to start a marking cycle, so we increment the 3841 // full collection counter. 3842 increment_old_marking_cycles_started(); 3843 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3844 } 3845 3846 _gc_tracer_stw->report_yc_type(yc_type()); 3847 3848 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3849 3850 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 3851 workers()->active_workers() : 1); 3852 double pause_start_sec = os::elapsedTime(); 3853 g1_policy()->phase_times()->note_gc_start(active_workers); 3854 log_gc_header(); 3855 3856 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3857 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3858 3859 // If the secondary_free_list is not empty, append it to the 3860 // free_list. No need to wait for the cleanup operation to finish; 3861 // the region allocation code will check the secondary_free_list 3862 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3863 // set, skip this step so that the region allocation code has to 3864 // get entries from the secondary_free_list. 3865 if (!G1StressConcRegionFreeing) { 3866 append_secondary_free_list_if_not_empty_with_lock(); 3867 } 3868 3869 assert(check_young_list_well_formed(), 3870 "young list should be well formed"); 3871 3872 // Don't dynamically change the number of GC threads this early. A value of 3873 // 0 is used to indicate serial work. When parallel work is done, 3874 // it will be set. 3875 3876 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3877 IsGCActiveMark x; 3878 3879 gc_prologue(false); 3880 increment_total_collections(false /* full gc */); 3881 increment_gc_time_stamp(); 3882 3883 verify_before_gc(); 3884 3885 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3886 3887 // Please see comment in g1CollectedHeap.hpp and 3888 // G1CollectedHeap::ref_processing_init() to see how 3889 // reference processing currently works in G1. 3890 3891 // Enable discovery in the STW reference processor 3892 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, 3893 true /*verify_no_refs*/); 3894 3895 { 3896 // We want to temporarily turn off discovery by the 3897 // CM ref processor, if necessary, and turn it back on 3898 // on again later if we do. Using a scoped 3899 // NoRefDiscovery object will do this. 3900 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3901 3902 // Forget the current alloc region (we might even choose it to be part 3903 // of the collection set!). 3904 release_mutator_alloc_region(); 3905 3906 // We should call this after we retire the mutator alloc 3907 // region(s) so that all the ALLOC / RETIRE events are generated 3908 // before the start GC event. 3909 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 3910 3911 // This timing is only used by the ergonomics to handle our pause target. 3912 // It is unclear why this should not include the full pause. We will 3913 // investigate this in CR 7178365. 3914 // 3915 // Preserving the old comment here if that helps the investigation: 3916 // 3917 // The elapsed time induced by the start time below deliberately elides 3918 // the possible verification above. 3919 double sample_start_time_sec = os::elapsedTime(); 3920 size_t start_used_bytes = used(); 3921 3922 #if YOUNG_LIST_VERBOSE 3923 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 3924 _young_list->print(); 3925 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3926 #endif // YOUNG_LIST_VERBOSE 3927 3928 g1_policy()->record_collection_pause_start(sample_start_time_sec, 3929 start_used_bytes); 3930 3931 double scan_wait_start = os::elapsedTime(); 3932 // We have to wait until the CM threads finish scanning the 3933 // root regions as it's the only way to ensure that all the 3934 // objects on them have been correctly scanned before we start 3935 // moving them during the GC. 3936 bool waited = _cm->root_regions()->wait_until_scan_finished(); 3937 double wait_time_ms = 0.0; 3938 if (waited) { 3939 double scan_wait_end = os::elapsedTime(); 3940 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 3941 } 3942 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 3943 3944 #if YOUNG_LIST_VERBOSE 3945 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 3946 _young_list->print(); 3947 #endif // YOUNG_LIST_VERBOSE 3948 3949 if (g1_policy()->during_initial_mark_pause()) { 3950 concurrent_mark()->checkpointRootsInitialPre(); 3951 } 3952 perm_gen()->save_marks(); 3953 3954 #if YOUNG_LIST_VERBOSE 3955 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 3956 _young_list->print(); 3957 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 3958 #endif // YOUNG_LIST_VERBOSE 3959 3960 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 3961 3962 _cm->note_start_of_gc(); 3963 // We should not verify the per-thread SATB buffers given that 3964 // we have not filtered them yet (we'll do so during the 3965 // GC). We also call this after finalize_cset() to 3966 // ensure that the CSet has been finalized. 3967 _cm->verify_no_cset_oops(true /* verify_stacks */, 3968 true /* verify_enqueued_buffers */, 3969 false /* verify_thread_buffers */, 3970 true /* verify_fingers */); 3971 3972 if (_hr_printer.is_active()) { 3973 HeapRegion* hr = g1_policy()->collection_set(); 3974 while (hr != NULL) { 3975 G1HRPrinter::RegionType type; 3976 if (!hr->is_young()) { 3977 type = G1HRPrinter::Old; 3978 } else if (hr->is_survivor()) { 3979 type = G1HRPrinter::Survivor; 3980 } else { 3981 type = G1HRPrinter::Eden; 3982 } 3983 _hr_printer.cset(hr); 3984 hr = hr->next_in_collection_set(); 3985 } 3986 } 3987 3988 #ifdef ASSERT 3989 VerifyCSetClosure cl; 3990 collection_set_iterate(&cl); 3991 #endif // ASSERT 3992 3993 setup_surviving_young_words(); 3994 3995 // Initialize the GC alloc regions. 3996 init_gc_alloc_regions(evacuation_info); 3997 3998 // Actually do the work... 3999 evacuate_collection_set(evacuation_info); 4000 4001 // We do this to mainly verify the per-thread SATB buffers 4002 // (which have been filtered by now) since we didn't verify 4003 // them earlier. No point in re-checking the stacks / enqueued 4004 // buffers given that the CSet has not changed since last time 4005 // we checked. 4006 _cm->verify_no_cset_oops(false /* verify_stacks */, 4007 false /* verify_enqueued_buffers */, 4008 true /* verify_thread_buffers */, 4009 true /* verify_fingers */); 4010 4011 free_collection_set(g1_policy()->collection_set(), evacuation_info); 4012 g1_policy()->clear_collection_set(); 4013 4014 cleanup_surviving_young_words(); 4015 4016 // Start a new incremental collection set for the next pause. 4017 g1_policy()->start_incremental_cset_building(); 4018 4019 // Clear the _cset_fast_test bitmap in anticipation of adding 4020 // regions to the incremental collection set for the next 4021 // evacuation pause. 4022 clear_cset_fast_test(); 4023 4024 _young_list->reset_sampled_info(); 4025 4026 // Don't check the whole heap at this point as the 4027 // GC alloc regions from this pause have been tagged 4028 // as survivors and moved on to the survivor list. 4029 // Survivor regions will fail the !is_young() check. 4030 assert(check_young_list_empty(false /* check_heap */), 4031 "young list should be empty"); 4032 4033 #if YOUNG_LIST_VERBOSE 4034 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 4035 _young_list->print(); 4036 #endif // YOUNG_LIST_VERBOSE 4037 4038 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 4039 _young_list->first_survivor_region(), 4040 _young_list->last_survivor_region()); 4041 4042 _young_list->reset_auxilary_lists(); 4043 4044 if (evacuation_failed()) { 4045 _summary_bytes_used = recalculate_used(); 4046 uint n_queues = MAX2((int)ParallelGCThreads, 1); 4047 for (uint i = 0; i < n_queues; i++) { 4048 if (_evacuation_failed_info_array[i].has_failed()) { 4049 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 4050 } 4051 } 4052 } else { 4053 // The "used" of the the collection set have already been subtracted 4054 // when they were freed. Add in the bytes evacuated. 4055 _summary_bytes_used += g1_policy()->bytes_copied_during_gc(); 4056 } 4057 4058 if (g1_policy()->during_initial_mark_pause()) { 4059 // We have to do this before we notify the CM threads that 4060 // they can start working to make sure that all the 4061 // appropriate initialization is done on the CM object. 4062 concurrent_mark()->checkpointRootsInitialPost(); 4063 set_marking_started(); 4064 // Note that we don't actually trigger the CM thread at 4065 // this point. We do that later when we're sure that 4066 // the current thread has completed its logging output. 4067 } 4068 4069 allocate_dummy_regions(); 4070 4071 #if YOUNG_LIST_VERBOSE 4072 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 4073 _young_list->print(); 4074 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4075 #endif // YOUNG_LIST_VERBOSE 4076 4077 init_mutator_alloc_region(); 4078 4079 { 4080 size_t expand_bytes = g1_policy()->expansion_amount(); 4081 if (expand_bytes > 0) { 4082 size_t bytes_before = capacity(); 4083 // No need for an ergo verbose message here, 4084 // expansion_amount() does this when it returns a value > 0. 4085 if (!expand(expand_bytes)) { 4086 // We failed to expand the heap so let's verify that 4087 // committed/uncommitted amount match the backing store 4088 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch"); 4089 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch"); 4090 } 4091 } 4092 } 4093 4094 // We redo the verification but now wrt to the new CSet which 4095 // has just got initialized after the previous CSet was freed. 4096 _cm->verify_no_cset_oops(true /* verify_stacks */, 4097 true /* verify_enqueued_buffers */, 4098 true /* verify_thread_buffers */, 4099 true /* verify_fingers */); 4100 _cm->note_end_of_gc(); 4101 4102 // This timing is only used by the ergonomics to handle our pause target. 4103 // It is unclear why this should not include the full pause. We will 4104 // investigate this in CR 7178365. 4105 double sample_end_time_sec = os::elapsedTime(); 4106 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 4107 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 4108 4109 MemoryService::track_memory_usage(); 4110 4111 // In prepare_for_verify() below we'll need to scan the deferred 4112 // update buffers to bring the RSets up-to-date if 4113 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4114 // the update buffers we'll probably need to scan cards on the 4115 // regions we just allocated to (i.e., the GC alloc 4116 // regions). However, during the last GC we called 4117 // set_saved_mark() on all the GC alloc regions, so card 4118 // scanning might skip the [saved_mark_word()...top()] area of 4119 // those regions (i.e., the area we allocated objects into 4120 // during the last GC). But it shouldn't. Given that 4121 // saved_mark_word() is conditional on whether the GC time stamp 4122 // on the region is current or not, by incrementing the GC time 4123 // stamp here we invalidate all the GC time stamps on all the 4124 // regions and saved_mark_word() will simply return top() for 4125 // all the regions. This is a nicer way of ensuring this rather 4126 // than iterating over the regions and fixing them. In fact, the 4127 // GC time stamp increment here also ensures that 4128 // saved_mark_word() will return top() between pauses, i.e., 4129 // during concurrent refinement. So we don't need the 4130 // is_gc_active() check to decided which top to use when 4131 // scanning cards (see CR 7039627). 4132 increment_gc_time_stamp(); 4133 4134 verify_after_gc(); 4135 4136 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4137 ref_processor_stw()->verify_no_references_recorded(); 4138 4139 // CM reference discovery will be re-enabled if necessary. 4140 } 4141 4142 // We should do this after we potentially expand the heap so 4143 // that all the COMMIT events are generated before the end GC 4144 // event, and after we retire the GC alloc regions so that all 4145 // RETIRE events are generated before the end GC event. 4146 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4147 4148 if (mark_in_progress()) { 4149 concurrent_mark()->update_g1_committed(); 4150 } 4151 4152 #ifdef TRACESPINNING 4153 ParallelTaskTerminator::print_termination_counts(); 4154 #endif 4155 4156 gc_epilogue(false); 4157 } 4158 4159 // Print the remainder of the GC log output. 4160 log_gc_footer(os::elapsedTime() - pause_start_sec); 4161 4162 // It is not yet to safe to tell the concurrent mark to 4163 // start as we have some optional output below. We don't want the 4164 // output from the concurrent mark thread interfering with this 4165 // logging output either. 4166 4167 _hrs.verify_optional(); 4168 verify_region_sets_optional(); 4169 4170 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats()); 4171 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4172 4173 print_heap_after_gc(); 4174 trace_heap_after_gc(_gc_tracer_stw); 4175 4176 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4177 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4178 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4179 // before any GC notifications are raised. 4180 g1mm()->update_sizes(); 4181 4182 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4183 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4184 _gc_timer_stw->register_gc_end(os::elapsed_counter()); 4185 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4186 } 4187 4188 if (G1SummarizeRSetStats && 4189 (G1SummarizeRSetStatsPeriod > 0) && 4190 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 4191 g1_rem_set()->print_summary_info(); 4192 } 4193 // It should now be safe to tell the concurrent mark thread to start 4194 // without its logging output interfering with the logging output 4195 // that came from the pause. 4196 4197 if (should_start_conc_mark) { 4198 // CAUTION: after the doConcurrentMark() call below, 4199 // the concurrent marking thread(s) could be running 4200 // concurrently with us. Make sure that anything after 4201 // this point does not assume that we are the only GC thread 4202 // running. Note: of course, the actual marking work will 4203 // not start until the safepoint itself is released in 4204 // ConcurrentGCThread::safepoint_desynchronize(). 4205 doConcurrentMark(); 4206 } 4207 4208 return true; 4209 } 4210 4211 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose) 4212 { 4213 size_t gclab_word_size; 4214 switch (purpose) { 4215 case GCAllocForSurvived: 4216 gclab_word_size = _survivor_plab_stats.desired_plab_sz(); 4217 break; 4218 case GCAllocForTenured: 4219 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4220 break; 4221 default: 4222 assert(false, "unknown GCAllocPurpose"); 4223 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4224 break; 4225 } 4226 4227 // Prevent humongous PLAB sizes for two reasons: 4228 // * PLABs are allocated using a similar paths as oops, but should 4229 // never be in a humongous region 4230 // * Allowing humongous PLABs needlessly churns the region free lists 4231 return MIN2(_humongous_object_threshold_in_words, gclab_word_size); 4232 } 4233 4234 void G1CollectedHeap::init_mutator_alloc_region() { 4235 assert(_mutator_alloc_region.get() == NULL, "pre-condition"); 4236 _mutator_alloc_region.init(); 4237 } 4238 4239 void G1CollectedHeap::release_mutator_alloc_region() { 4240 _mutator_alloc_region.release(); 4241 assert(_mutator_alloc_region.get() == NULL, "post-condition"); 4242 } 4243 4244 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) { 4245 assert_at_safepoint(true /* should_be_vm_thread */); 4246 4247 _survivor_gc_alloc_region.init(); 4248 _old_gc_alloc_region.init(); 4249 HeapRegion* retained_region = _retained_old_gc_alloc_region; 4250 _retained_old_gc_alloc_region = NULL; 4251 4252 // We will discard the current GC alloc region if: 4253 // a) it's in the collection set (it can happen!), 4254 // b) it's already full (no point in using it), 4255 // c) it's empty (this means that it was emptied during 4256 // a cleanup and it should be on the free list now), or 4257 // d) it's humongous (this means that it was emptied 4258 // during a cleanup and was added to the free list, but 4259 // has been subsequently used to allocate a humongous 4260 // object that may be less than the region size). 4261 if (retained_region != NULL && 4262 !retained_region->in_collection_set() && 4263 !(retained_region->top() == retained_region->end()) && 4264 !retained_region->is_empty() && 4265 !retained_region->isHumongous()) { 4266 retained_region->set_saved_mark(); 4267 // The retained region was added to the old region set when it was 4268 // retired. We have to remove it now, since we don't allow regions 4269 // we allocate to in the region sets. We'll re-add it later, when 4270 // it's retired again. 4271 _old_set.remove(retained_region); 4272 bool during_im = g1_policy()->during_initial_mark_pause(); 4273 retained_region->note_start_of_copying(during_im); 4274 _old_gc_alloc_region.set(retained_region); 4275 _hr_printer.reuse(retained_region); 4276 evacuation_info.set_alloc_regions_used_before(retained_region->used()); 4277 } 4278 } 4279 4280 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) { 4281 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() + 4282 _old_gc_alloc_region.count()); 4283 _survivor_gc_alloc_region.release(); 4284 // If we have an old GC alloc region to release, we'll save it in 4285 // _retained_old_gc_alloc_region. If we don't 4286 // _retained_old_gc_alloc_region will become NULL. This is what we 4287 // want either way so no reason to check explicitly for either 4288 // condition. 4289 _retained_old_gc_alloc_region = _old_gc_alloc_region.release(); 4290 4291 if (ResizePLAB) { 4292 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4293 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4294 } 4295 } 4296 4297 void G1CollectedHeap::abandon_gc_alloc_regions() { 4298 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition"); 4299 assert(_old_gc_alloc_region.get() == NULL, "pre-condition"); 4300 _retained_old_gc_alloc_region = NULL; 4301 } 4302 4303 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4304 _drain_in_progress = false; 4305 set_evac_failure_closure(cl); 4306 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4307 } 4308 4309 void G1CollectedHeap::finalize_for_evac_failure() { 4310 assert(_evac_failure_scan_stack != NULL && 4311 _evac_failure_scan_stack->length() == 0, 4312 "Postcondition"); 4313 assert(!_drain_in_progress, "Postcondition"); 4314 delete _evac_failure_scan_stack; 4315 _evac_failure_scan_stack = NULL; 4316 } 4317 4318 void G1CollectedHeap::remove_self_forwarding_pointers() { 4319 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4320 4321 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4322 4323 if (G1CollectedHeap::use_parallel_gc_threads()) { 4324 set_par_threads(); 4325 workers()->run_task(&rsfp_task); 4326 set_par_threads(0); 4327 } else { 4328 rsfp_task.work(0); 4329 } 4330 4331 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity"); 4332 4333 // Reset the claim values in the regions in the collection set. 4334 reset_cset_heap_region_claim_values(); 4335 4336 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4337 4338 // Now restore saved marks, if any. 4339 assert(_objs_with_preserved_marks.size() == 4340 _preserved_marks_of_objs.size(), "Both or none."); 4341 while (!_objs_with_preserved_marks.is_empty()) { 4342 oop obj = _objs_with_preserved_marks.pop(); 4343 markOop m = _preserved_marks_of_objs.pop(); 4344 obj->set_mark(m); 4345 } 4346 _objs_with_preserved_marks.clear(true); 4347 _preserved_marks_of_objs.clear(true); 4348 } 4349 4350 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4351 _evac_failure_scan_stack->push(obj); 4352 } 4353 4354 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4355 assert(_evac_failure_scan_stack != NULL, "precondition"); 4356 4357 while (_evac_failure_scan_stack->length() > 0) { 4358 oop obj = _evac_failure_scan_stack->pop(); 4359 _evac_failure_closure->set_region(heap_region_containing(obj)); 4360 obj->oop_iterate_backwards(_evac_failure_closure); 4361 } 4362 } 4363 4364 oop 4365 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4366 oop old) { 4367 assert(obj_in_cs(old), 4368 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4369 (HeapWord*) old)); 4370 markOop m = old->mark(); 4371 oop forward_ptr = old->forward_to_atomic(old); 4372 if (forward_ptr == NULL) { 4373 // Forward-to-self succeeded. 4374 assert(_par_scan_state != NULL, "par scan state"); 4375 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4376 uint queue_num = _par_scan_state->queue_num(); 4377 4378 _evacuation_failed = true; 4379 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4380 if (_evac_failure_closure != cl) { 4381 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4382 assert(!_drain_in_progress, 4383 "Should only be true while someone holds the lock."); 4384 // Set the global evac-failure closure to the current thread's. 4385 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4386 set_evac_failure_closure(cl); 4387 // Now do the common part. 4388 handle_evacuation_failure_common(old, m); 4389 // Reset to NULL. 4390 set_evac_failure_closure(NULL); 4391 } else { 4392 // The lock is already held, and this is recursive. 4393 assert(_drain_in_progress, "This should only be the recursive case."); 4394 handle_evacuation_failure_common(old, m); 4395 } 4396 return old; 4397 } else { 4398 // Forward-to-self failed. Either someone else managed to allocate 4399 // space for this object (old != forward_ptr) or they beat us in 4400 // self-forwarding it (old == forward_ptr). 4401 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4402 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4403 "should not be in the CSet", 4404 (HeapWord*) old, (HeapWord*) forward_ptr)); 4405 return forward_ptr; 4406 } 4407 } 4408 4409 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4410 preserve_mark_if_necessary(old, m); 4411 4412 HeapRegion* r = heap_region_containing(old); 4413 if (!r->evacuation_failed()) { 4414 r->set_evacuation_failed(true); 4415 _hr_printer.evac_failure(r); 4416 } 4417 4418 push_on_evac_failure_scan_stack(old); 4419 4420 if (!_drain_in_progress) { 4421 // prevent recursion in copy_to_survivor_space() 4422 _drain_in_progress = true; 4423 drain_evac_failure_scan_stack(); 4424 _drain_in_progress = false; 4425 } 4426 } 4427 4428 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4429 assert(evacuation_failed(), "Oversaving!"); 4430 // We want to call the "for_promotion_failure" version only in the 4431 // case of a promotion failure. 4432 if (m->must_be_preserved_for_promotion_failure(obj)) { 4433 _objs_with_preserved_marks.push(obj); 4434 _preserved_marks_of_objs.push(m); 4435 } 4436 } 4437 4438 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose, 4439 size_t word_size) { 4440 if (purpose == GCAllocForSurvived) { 4441 HeapWord* result = survivor_attempt_allocation(word_size); 4442 if (result != NULL) { 4443 return result; 4444 } else { 4445 // Let's try to allocate in the old gen in case we can fit the 4446 // object there. 4447 return old_attempt_allocation(word_size); 4448 } 4449 } else { 4450 assert(purpose == GCAllocForTenured, "sanity"); 4451 HeapWord* result = old_attempt_allocation(word_size); 4452 if (result != NULL) { 4453 return result; 4454 } else { 4455 // Let's try to allocate in the survivors in case we can fit the 4456 // object there. 4457 return survivor_attempt_allocation(word_size); 4458 } 4459 } 4460 4461 ShouldNotReachHere(); 4462 // Trying to keep some compilers happy. 4463 return NULL; 4464 } 4465 4466 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) : 4467 ParGCAllocBuffer(gclab_word_size), _retired(false) { } 4468 4469 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num) 4470 : _g1h(g1h), 4471 _refs(g1h->task_queue(queue_num)), 4472 _dcq(&g1h->dirty_card_queue_set()), 4473 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()), 4474 _g1_rem(g1h->g1_rem_set()), 4475 _hash_seed(17), _queue_num(queue_num), 4476 _term_attempts(0), 4477 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)), 4478 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)), 4479 _age_table(false), 4480 _strong_roots_time(0), _term_time(0), 4481 _alloc_buffer_waste(0), _undo_waste(0) { 4482 // we allocate G1YoungSurvRateNumRegions plus one entries, since 4483 // we "sacrifice" entry 0 to keep track of surviving bytes for 4484 // non-young regions (where the age is -1) 4485 // We also add a few elements at the beginning and at the end in 4486 // an attempt to eliminate cache contention 4487 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length(); 4488 uint array_length = PADDING_ELEM_NUM + 4489 real_length + 4490 PADDING_ELEM_NUM; 4491 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC); 4492 if (_surviving_young_words_base == NULL) 4493 vm_exit_out_of_memory(array_length * sizeof(size_t), 4494 "Not enough space for young surv histo."); 4495 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM; 4496 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t)); 4497 4498 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer; 4499 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer; 4500 4501 _start = os::elapsedTime(); 4502 } 4503 4504 void 4505 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st) 4506 { 4507 st->print_raw_cr("GC Termination Stats"); 4508 st->print_raw_cr(" elapsed --strong roots-- -------termination-------" 4509 " ------waste (KiB)------"); 4510 st->print_raw_cr("thr ms ms % ms % attempts" 4511 " total alloc undo"); 4512 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------" 4513 " ------- ------- -------"); 4514 } 4515 4516 void 4517 G1ParScanThreadState::print_termination_stats(int i, 4518 outputStream* const st) const 4519 { 4520 const double elapsed_ms = elapsed_time() * 1000.0; 4521 const double s_roots_ms = strong_roots_time() * 1000.0; 4522 const double term_ms = term_time() * 1000.0; 4523 st->print_cr("%3d %9.2f %9.2f %6.2f " 4524 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 4525 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 4526 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms, 4527 term_ms, term_ms * 100 / elapsed_ms, term_attempts(), 4528 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K, 4529 alloc_buffer_waste() * HeapWordSize / K, 4530 undo_waste() * HeapWordSize / K); 4531 } 4532 4533 #ifdef ASSERT 4534 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const { 4535 assert(ref != NULL, "invariant"); 4536 assert(UseCompressedOops, "sanity"); 4537 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref)); 4538 oop p = oopDesc::load_decode_heap_oop(ref); 4539 assert(_g1h->is_in_g1_reserved(p), 4540 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p))); 4541 return true; 4542 } 4543 4544 bool G1ParScanThreadState::verify_ref(oop* ref) const { 4545 assert(ref != NULL, "invariant"); 4546 if (has_partial_array_mask(ref)) { 4547 // Must be in the collection set--it's already been copied. 4548 oop p = clear_partial_array_mask(ref); 4549 assert(_g1h->obj_in_cs(p), 4550 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p))); 4551 } else { 4552 oop p = oopDesc::load_decode_heap_oop(ref); 4553 assert(_g1h->is_in_g1_reserved(p), 4554 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p))); 4555 } 4556 return true; 4557 } 4558 4559 bool G1ParScanThreadState::verify_task(StarTask ref) const { 4560 if (ref.is_narrow()) { 4561 return verify_ref((narrowOop*) ref); 4562 } else { 4563 return verify_ref((oop*) ref); 4564 } 4565 } 4566 #endif // ASSERT 4567 4568 void G1ParScanThreadState::trim_queue() { 4569 assert(_evac_cl != NULL, "not set"); 4570 assert(_evac_failure_cl != NULL, "not set"); 4571 assert(_partial_scan_cl != NULL, "not set"); 4572 4573 StarTask ref; 4574 do { 4575 // Drain the overflow stack first, so other threads can steal. 4576 while (refs()->pop_overflow(ref)) { 4577 deal_with_reference(ref); 4578 } 4579 4580 while (refs()->pop_local(ref)) { 4581 deal_with_reference(ref); 4582 } 4583 } while (!refs()->is_empty()); 4584 } 4585 4586 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, 4587 G1ParScanThreadState* par_scan_state) : 4588 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()), 4589 _par_scan_state(par_scan_state), 4590 _worker_id(par_scan_state->queue_num()), 4591 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()), 4592 _mark_in_progress(_g1->mark_in_progress()) { } 4593 4594 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object> 4595 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>::mark_object(oop obj) { 4596 #ifdef ASSERT 4597 HeapRegion* hr = _g1->heap_region_containing(obj); 4598 assert(hr != NULL, "sanity"); 4599 assert(!hr->in_collection_set(), "should not mark objects in the CSet"); 4600 #endif // ASSERT 4601 4602 // We know that the object is not moving so it's safe to read its size. 4603 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4604 } 4605 4606 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object> 4607 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object> 4608 ::mark_forwarded_object(oop from_obj, oop to_obj) { 4609 #ifdef ASSERT 4610 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4611 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4612 assert(from_obj != to_obj, "should not be self-forwarded"); 4613 4614 HeapRegion* from_hr = _g1->heap_region_containing(from_obj); 4615 assert(from_hr != NULL, "sanity"); 4616 assert(from_hr->in_collection_set(), "from obj should be in the CSet"); 4617 4618 HeapRegion* to_hr = _g1->heap_region_containing(to_obj); 4619 assert(to_hr != NULL, "sanity"); 4620 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet"); 4621 #endif // ASSERT 4622 4623 // The object might be in the process of being copied by another 4624 // worker so we cannot trust that its to-space image is 4625 // well-formed. So we have to read its size from its from-space 4626 // image which we know should not be changing. 4627 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4628 } 4629 4630 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object> 4631 oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object> 4632 ::copy_to_survivor_space(oop old) { 4633 size_t word_sz = old->size(); 4634 HeapRegion* from_region = _g1->heap_region_containing_raw(old); 4635 // +1 to make the -1 indexes valid... 4636 int young_index = from_region->young_index_in_cset()+1; 4637 assert( (from_region->is_young() && young_index > 0) || 4638 (!from_region->is_young() && young_index == 0), "invariant" ); 4639 G1CollectorPolicy* g1p = _g1->g1_policy(); 4640 markOop m = old->mark(); 4641 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age() 4642 : m->age(); 4643 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age, 4644 word_sz); 4645 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz); 4646 #ifndef PRODUCT 4647 // Should this evacuation fail? 4648 if (_g1->evacuation_should_fail()) { 4649 if (obj_ptr != NULL) { 4650 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz); 4651 obj_ptr = NULL; 4652 } 4653 } 4654 #endif // !PRODUCT 4655 4656 if (obj_ptr == NULL) { 4657 // This will either forward-to-self, or detect that someone else has 4658 // installed a forwarding pointer. 4659 return _g1->handle_evacuation_failure_par(_par_scan_state, old); 4660 } 4661 4662 oop obj = oop(obj_ptr); 4663 4664 // We're going to allocate linearly, so might as well prefetch ahead. 4665 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes); 4666 4667 oop forward_ptr = old->forward_to_atomic(obj); 4668 if (forward_ptr == NULL) { 4669 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz); 4670 if (g1p->track_object_age(alloc_purpose)) { 4671 // We could simply do obj->incr_age(). However, this causes a 4672 // performance issue. obj->incr_age() will first check whether 4673 // the object has a displaced mark by checking its mark word; 4674 // getting the mark word from the new location of the object 4675 // stalls. So, given that we already have the mark word and we 4676 // are about to install it anyway, it's better to increase the 4677 // age on the mark word, when the object does not have a 4678 // displaced mark word. We're not expecting many objects to have 4679 // a displaced marked word, so that case is not optimized 4680 // further (it could be...) and we simply call obj->incr_age(). 4681 4682 if (m->has_displaced_mark_helper()) { 4683 // in this case, we have to install the mark word first, 4684 // otherwise obj looks to be forwarded (the old mark word, 4685 // which contains the forward pointer, was copied) 4686 obj->set_mark(m); 4687 obj->incr_age(); 4688 } else { 4689 m = m->incr_age(); 4690 obj->set_mark(m); 4691 } 4692 _par_scan_state->age_table()->add(obj, word_sz); 4693 } else { 4694 obj->set_mark(m); 4695 } 4696 4697 size_t* surv_young_words = _par_scan_state->surviving_young_words(); 4698 surv_young_words[young_index] += word_sz; 4699 4700 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) { 4701 // We keep track of the next start index in the length field of 4702 // the to-space object. The actual length can be found in the 4703 // length field of the from-space object. 4704 arrayOop(obj)->set_length(0); 4705 oop* old_p = set_partial_array_mask(old); 4706 _par_scan_state->push_on_queue(old_p); 4707 } else { 4708 // No point in using the slower heap_region_containing() method, 4709 // given that we know obj is in the heap. 4710 _scanner.set_region(_g1->heap_region_containing_raw(obj)); 4711 obj->oop_iterate_backwards(&_scanner); 4712 } 4713 } else { 4714 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz); 4715 obj = forward_ptr; 4716 } 4717 return obj; 4718 } 4719 4720 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object> 4721 template <class T> 4722 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object> 4723 ::do_oop_work(T* p) { 4724 oop obj = oopDesc::load_decode_heap_oop(p); 4725 assert(barrier != G1BarrierRS || obj != NULL, 4726 "Precondition: G1BarrierRS implies obj is non-NULL"); 4727 4728 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4729 4730 // here the null check is implicit in the cset_fast_test() test 4731 if (_g1->in_cset_fast_test(obj)) { 4732 oop forwardee; 4733 if (obj->is_forwarded()) { 4734 forwardee = obj->forwardee(); 4735 } else { 4736 forwardee = copy_to_survivor_space(obj); 4737 } 4738 assert(forwardee != NULL, "forwardee should not be NULL"); 4739 oopDesc::encode_store_heap_oop(p, forwardee); 4740 if (do_mark_object && forwardee != obj) { 4741 // If the object is self-forwarded we don't need to explicitly 4742 // mark it, the evacuation failure protocol will do so. 4743 mark_forwarded_object(obj, forwardee); 4744 } 4745 4746 // When scanning the RS, we only care about objs in CS. 4747 if (barrier == G1BarrierRS) { 4748 _par_scan_state->update_rs(_from, p, _worker_id); 4749 } 4750 } else { 4751 // The object is not in collection set. If we're a root scanning 4752 // closure during an initial mark pause (i.e. do_mark_object will 4753 // be true) then attempt to mark the object. 4754 if (do_mark_object && _g1->is_in_g1_reserved(obj)) { 4755 mark_object(obj); 4756 } 4757 } 4758 4759 if (barrier == G1BarrierEvac && obj != NULL) { 4760 _par_scan_state->update_rs(_from, p, _worker_id); 4761 } 4762 4763 if (do_gen_barrier && obj != NULL) { 4764 par_do_barrier(p); 4765 } 4766 } 4767 4768 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p); 4769 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p); 4770 4771 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) { 4772 assert(has_partial_array_mask(p), "invariant"); 4773 oop from_obj = clear_partial_array_mask(p); 4774 4775 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap."); 4776 assert(from_obj->is_objArray(), "must be obj array"); 4777 objArrayOop from_obj_array = objArrayOop(from_obj); 4778 // The from-space object contains the real length. 4779 int length = from_obj_array->length(); 4780 4781 assert(from_obj->is_forwarded(), "must be forwarded"); 4782 oop to_obj = from_obj->forwardee(); 4783 assert(from_obj != to_obj, "should not be chunking self-forwarded objects"); 4784 objArrayOop to_obj_array = objArrayOop(to_obj); 4785 // We keep track of the next start index in the length field of the 4786 // to-space object. 4787 int next_index = to_obj_array->length(); 4788 assert(0 <= next_index && next_index < length, 4789 err_msg("invariant, next index: %d, length: %d", next_index, length)); 4790 4791 int start = next_index; 4792 int end = length; 4793 int remainder = end - start; 4794 // We'll try not to push a range that's smaller than ParGCArrayScanChunk. 4795 if (remainder > 2 * ParGCArrayScanChunk) { 4796 end = start + ParGCArrayScanChunk; 4797 to_obj_array->set_length(end); 4798 // Push the remainder before we process the range in case another 4799 // worker has run out of things to do and can steal it. 4800 oop* from_obj_p = set_partial_array_mask(from_obj); 4801 _par_scan_state->push_on_queue(from_obj_p); 4802 } else { 4803 assert(length == end, "sanity"); 4804 // We'll process the final range for this object. Restore the length 4805 // so that the heap remains parsable in case of evacuation failure. 4806 to_obj_array->set_length(end); 4807 } 4808 _scanner.set_region(_g1->heap_region_containing_raw(to_obj)); 4809 // Process indexes [start,end). It will also process the header 4810 // along with the first chunk (i.e., the chunk with start == 0). 4811 // Note that at this point the length field of to_obj_array is not 4812 // correct given that we are using it to keep track of the next 4813 // start index. oop_iterate_range() (thankfully!) ignores the length 4814 // field and only relies on the start / end parameters. It does 4815 // however return the size of the object which will be incorrect. So 4816 // we have to ignore it even if we wanted to use it. 4817 to_obj_array->oop_iterate_range(&_scanner, start, end); 4818 } 4819 4820 class G1ParEvacuateFollowersClosure : public VoidClosure { 4821 protected: 4822 G1CollectedHeap* _g1h; 4823 G1ParScanThreadState* _par_scan_state; 4824 RefToScanQueueSet* _queues; 4825 ParallelTaskTerminator* _terminator; 4826 4827 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4828 RefToScanQueueSet* queues() { return _queues; } 4829 ParallelTaskTerminator* terminator() { return _terminator; } 4830 4831 public: 4832 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4833 G1ParScanThreadState* par_scan_state, 4834 RefToScanQueueSet* queues, 4835 ParallelTaskTerminator* terminator) 4836 : _g1h(g1h), _par_scan_state(par_scan_state), 4837 _queues(queues), _terminator(terminator) {} 4838 4839 void do_void(); 4840 4841 private: 4842 inline bool offer_termination(); 4843 }; 4844 4845 bool G1ParEvacuateFollowersClosure::offer_termination() { 4846 G1ParScanThreadState* const pss = par_scan_state(); 4847 pss->start_term_time(); 4848 const bool res = terminator()->offer_termination(); 4849 pss->end_term_time(); 4850 return res; 4851 } 4852 4853 void G1ParEvacuateFollowersClosure::do_void() { 4854 StarTask stolen_task; 4855 G1ParScanThreadState* const pss = par_scan_state(); 4856 pss->trim_queue(); 4857 4858 do { 4859 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) { 4860 assert(pss->verify_task(stolen_task), "sanity"); 4861 if (stolen_task.is_narrow()) { 4862 pss->deal_with_reference((narrowOop*) stolen_task); 4863 } else { 4864 pss->deal_with_reference((oop*) stolen_task); 4865 } 4866 4867 // We've just processed a reference and we might have made 4868 // available new entries on the queues. So we have to make sure 4869 // we drain the queues as necessary. 4870 pss->trim_queue(); 4871 } 4872 } while (!offer_termination()); 4873 4874 pss->retire_alloc_buffers(); 4875 } 4876 4877 class G1ParTask : public AbstractGangTask { 4878 protected: 4879 G1CollectedHeap* _g1h; 4880 RefToScanQueueSet *_queues; 4881 ParallelTaskTerminator _terminator; 4882 uint _n_workers; 4883 4884 Mutex _stats_lock; 4885 Mutex* stats_lock() { return &_stats_lock; } 4886 4887 size_t getNCards() { 4888 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1) 4889 / G1BlockOffsetSharedArray::N_bytes; 4890 } 4891 4892 public: 4893 G1ParTask(G1CollectedHeap* g1h, 4894 RefToScanQueueSet *task_queues) 4895 : AbstractGangTask("G1 collection"), 4896 _g1h(g1h), 4897 _queues(task_queues), 4898 _terminator(0, _queues), 4899 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4900 {} 4901 4902 RefToScanQueueSet* queues() { return _queues; } 4903 4904 RefToScanQueue *work_queue(int i) { 4905 return queues()->queue(i); 4906 } 4907 4908 ParallelTaskTerminator* terminator() { return &_terminator; } 4909 4910 virtual void set_for_termination(int active_workers) { 4911 // This task calls set_n_termination() in par_non_clean_card_iterate_work() 4912 // in the young space (_par_seq_tasks) in the G1 heap 4913 // for SequentialSubTasksDone. 4914 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap 4915 // both of which need setting by set_n_termination(). 4916 _g1h->SharedHeap::set_n_termination(active_workers); 4917 _g1h->set_n_termination(active_workers); 4918 terminator()->reset_for_reuse(active_workers); 4919 _n_workers = active_workers; 4920 } 4921 4922 void work(uint worker_id) { 4923 if (worker_id >= _n_workers) return; // no work needed this round 4924 4925 double start_time_ms = os::elapsedTime() * 1000.0; 4926 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms); 4927 4928 { 4929 ResourceMark rm; 4930 HandleMark hm; 4931 4932 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 4933 4934 G1ParScanThreadState pss(_g1h, worker_id); 4935 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp); 4936 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 4937 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp); 4938 4939 pss.set_evac_closure(&scan_evac_cl); 4940 pss.set_evac_failure_closure(&evac_failure_cl); 4941 pss.set_partial_scan_closure(&partial_scan_cl); 4942 4943 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp); 4944 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss, rp); 4945 4946 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp); 4947 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss, rp); 4948 4949 OopClosure* scan_root_cl = &only_scan_root_cl; 4950 OopsInHeapRegionClosure* scan_perm_cl = &only_scan_perm_cl; 4951 4952 if (_g1h->g1_policy()->during_initial_mark_pause()) { 4953 // We also need to mark copied objects. 4954 scan_root_cl = &scan_mark_root_cl; 4955 scan_perm_cl = &scan_mark_perm_cl; 4956 } 4957 4958 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 4959 4960 pss.start_strong_roots(); 4961 _g1h->g1_process_strong_roots(/* not collecting perm */ false, 4962 SharedHeap::SO_AllClasses, 4963 scan_root_cl, 4964 &push_heap_rs_cl, 4965 scan_perm_cl, 4966 worker_id); 4967 pss.end_strong_roots(); 4968 4969 { 4970 double start = os::elapsedTime(); 4971 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 4972 evac.do_void(); 4973 double elapsed_ms = (os::elapsedTime()-start)*1000.0; 4974 double term_ms = pss.term_time()*1000.0; 4975 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms); 4976 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts()); 4977 } 4978 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 4979 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 4980 4981 if (ParallelGCVerbose) { 4982 MutexLocker x(stats_lock()); 4983 pss.print_termination_stats(worker_id); 4984 } 4985 4986 assert(pss.refs()->is_empty(), "should be empty"); 4987 4988 // Close the inner scope so that the ResourceMark and HandleMark 4989 // destructors are executed here and are included as part of the 4990 // "GC Worker Time". 4991 } 4992 4993 double end_time_ms = os::elapsedTime() * 1000.0; 4994 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms); 4995 } 4996 }; 4997 4998 // *** Common G1 Evacuation Stuff 4999 5000 // Closures that support the filtering of CodeBlobs scanned during 5001 // external root scanning. 5002 5003 // Closure applied to reference fields in code blobs (specifically nmethods) 5004 // to determine whether an nmethod contains references that point into 5005 // the collection set. Used as a predicate when walking code roots so 5006 // that only nmethods that point into the collection set are added to the 5007 // 'marked' list. 5008 5009 class G1FilteredCodeBlobToOopClosure : public CodeBlobToOopClosure { 5010 5011 class G1PointsIntoCSOopClosure : public OopClosure { 5012 G1CollectedHeap* _g1; 5013 bool _points_into_cs; 5014 public: 5015 G1PointsIntoCSOopClosure(G1CollectedHeap* g1) : 5016 _g1(g1), _points_into_cs(false) { } 5017 5018 bool points_into_cs() const { return _points_into_cs; } 5019 5020 template <class T> 5021 void do_oop_nv(T* p) { 5022 if (!_points_into_cs) { 5023 T heap_oop = oopDesc::load_heap_oop(p); 5024 if (!oopDesc::is_null(heap_oop) && 5025 _g1->in_cset_fast_test(oopDesc::decode_heap_oop_not_null(heap_oop))) { 5026 _points_into_cs = true; 5027 } 5028 } 5029 } 5030 5031 virtual void do_oop(oop* p) { do_oop_nv(p); } 5032 virtual void do_oop(narrowOop* p) { do_oop_nv(p); } 5033 }; 5034 5035 G1CollectedHeap* _g1; 5036 5037 public: 5038 G1FilteredCodeBlobToOopClosure(G1CollectedHeap* g1, OopClosure* cl) : 5039 CodeBlobToOopClosure(cl, true), _g1(g1) { } 5040 5041 virtual void do_code_blob(CodeBlob* cb) { 5042 nmethod* nm = cb->as_nmethod_or_null(); 5043 if (nm != NULL && !(nm->test_oops_do_mark())) { 5044 G1PointsIntoCSOopClosure predicate_cl(_g1); 5045 nm->oops_do(&predicate_cl); 5046 5047 if (predicate_cl.points_into_cs()) { 5048 // At least one of the reference fields or the oop relocations 5049 // in the nmethod points into the collection set. We have to 5050 // 'mark' this nmethod. 5051 // Note: Revisit the following if CodeBlobToOopClosure::do_code_blob() 5052 // or MarkingCodeBlobClosure::do_code_blob() change. 5053 if (!nm->test_set_oops_do_mark()) { 5054 do_newly_marked_nmethod(nm); 5055 } 5056 } 5057 } 5058 } 5059 }; 5060 5061 // This method is run in a GC worker. 5062 5063 void 5064 G1CollectedHeap:: 5065 g1_process_strong_roots(bool collecting_perm_gen, 5066 ScanningOption so, 5067 OopClosure* scan_non_heap_roots, 5068 OopsInHeapRegionClosure* scan_rs, 5069 OopsInGenClosure* scan_perm, 5070 int worker_i) { 5071 5072 // First scan the strong roots, including the perm gen. 5073 double ext_roots_start = os::elapsedTime(); 5074 double closure_app_time_sec = 0.0; 5075 5076 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots); 5077 BufferingOopsInGenClosure buf_scan_perm(scan_perm); 5078 buf_scan_perm.set_generation(perm_gen()); 5079 5080 // Walk the code cache w/o buffering, because StarTask cannot handle 5081 // unaligned oop locations. 5082 G1FilteredCodeBlobToOopClosure eager_scan_code_roots(this, scan_non_heap_roots); 5083 5084 process_strong_roots(false, // no scoping; this is parallel code 5085 collecting_perm_gen, so, 5086 &buf_scan_non_heap_roots, 5087 &eager_scan_code_roots, 5088 &buf_scan_perm); 5089 5090 // Now the CM ref_processor roots. 5091 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) { 5092 // We need to treat the discovered reference lists of the 5093 // concurrent mark ref processor as roots and keep entries 5094 // (which are added by the marking threads) on them live 5095 // until they can be processed at the end of marking. 5096 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots); 5097 } 5098 5099 // Finish up any enqueued closure apps (attributed as object copy time). 5100 buf_scan_non_heap_roots.done(); 5101 buf_scan_perm.done(); 5102 5103 double obj_copy_time_sec = buf_scan_perm.closure_app_seconds() + 5104 buf_scan_non_heap_roots.closure_app_seconds(); 5105 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0); 5106 5107 double ext_root_time_ms = 5108 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0; 5109 5110 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms); 5111 5112 // During conc marking we have to filter the per-thread SATB buffers 5113 // to make sure we remove any oops into the CSet (which will show up 5114 // as implicitly live). 5115 double satb_filtering_ms = 0.0; 5116 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) { 5117 if (mark_in_progress()) { 5118 double satb_filter_start = os::elapsedTime(); 5119 5120 JavaThread::satb_mark_queue_set().filter_thread_buffers(); 5121 5122 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0; 5123 } 5124 } 5125 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms); 5126 5127 // Now scan the complement of the collection set. 5128 if (scan_rs != NULL) { 5129 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i); 5130 } 5131 5132 _process_strong_tasks->all_tasks_completed(); 5133 } 5134 5135 void 5136 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure, 5137 OopClosure* non_root_closure) { 5138 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false); 5139 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure); 5140 } 5141 5142 // Weak Reference Processing support 5143 5144 // An always "is_alive" closure that is used to preserve referents. 5145 // If the object is non-null then it's alive. Used in the preservation 5146 // of referent objects that are pointed to by reference objects 5147 // discovered by the CM ref processor. 5148 class G1AlwaysAliveClosure: public BoolObjectClosure { 5149 G1CollectedHeap* _g1; 5150 public: 5151 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5152 void do_object(oop p) { assert(false, "Do not call."); } 5153 bool do_object_b(oop p) { 5154 if (p != NULL) { 5155 return true; 5156 } 5157 return false; 5158 } 5159 }; 5160 5161 bool G1STWIsAliveClosure::do_object_b(oop p) { 5162 // An object is reachable if it is outside the collection set, 5163 // or is inside and copied. 5164 return !_g1->obj_in_cs(p) || p->is_forwarded(); 5165 } 5166 5167 // Non Copying Keep Alive closure 5168 class G1KeepAliveClosure: public OopClosure { 5169 G1CollectedHeap* _g1; 5170 public: 5171 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5172 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 5173 void do_oop( oop* p) { 5174 oop obj = *p; 5175 5176 if (_g1->obj_in_cs(obj)) { 5177 assert( obj->is_forwarded(), "invariant" ); 5178 *p = obj->forwardee(); 5179 } 5180 } 5181 }; 5182 5183 // Copying Keep Alive closure - can be called from both 5184 // serial and parallel code as long as different worker 5185 // threads utilize different G1ParScanThreadState instances 5186 // and different queues. 5187 5188 class G1CopyingKeepAliveClosure: public OopClosure { 5189 G1CollectedHeap* _g1h; 5190 OopClosure* _copy_non_heap_obj_cl; 5191 OopsInHeapRegionClosure* _copy_perm_obj_cl; 5192 G1ParScanThreadState* _par_scan_state; 5193 5194 public: 5195 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 5196 OopClosure* non_heap_obj_cl, 5197 OopsInHeapRegionClosure* perm_obj_cl, 5198 G1ParScanThreadState* pss): 5199 _g1h(g1h), 5200 _copy_non_heap_obj_cl(non_heap_obj_cl), 5201 _copy_perm_obj_cl(perm_obj_cl), 5202 _par_scan_state(pss) 5203 {} 5204 5205 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 5206 virtual void do_oop( oop* p) { do_oop_work(p); } 5207 5208 template <class T> void do_oop_work(T* p) { 5209 oop obj = oopDesc::load_decode_heap_oop(p); 5210 5211 if (_g1h->obj_in_cs(obj)) { 5212 // If the referent object has been forwarded (either copied 5213 // to a new location or to itself in the event of an 5214 // evacuation failure) then we need to update the reference 5215 // field and, if both reference and referent are in the G1 5216 // heap, update the RSet for the referent. 5217 // 5218 // If the referent has not been forwarded then we have to keep 5219 // it alive by policy. Therefore we have copy the referent. 5220 // 5221 // If the reference field is in the G1 heap then we can push 5222 // on the PSS queue. When the queue is drained (after each 5223 // phase of reference processing) the object and it's followers 5224 // will be copied, the reference field set to point to the 5225 // new location, and the RSet updated. Otherwise we need to 5226 // use the the non-heap or perm closures directly to copy 5227 // the referent object and update the pointer, while avoiding 5228 // updating the RSet. 5229 5230 if (_g1h->is_in_g1_reserved(p)) { 5231 _par_scan_state->push_on_queue(p); 5232 } else { 5233 // The reference field is not in the G1 heap. 5234 if (_g1h->perm_gen()->is_in(p)) { 5235 _copy_perm_obj_cl->do_oop(p); 5236 } else { 5237 _copy_non_heap_obj_cl->do_oop(p); 5238 } 5239 } 5240 } 5241 } 5242 }; 5243 5244 // Serial drain queue closure. Called as the 'complete_gc' 5245 // closure for each discovered list in some of the 5246 // reference processing phases. 5247 5248 class G1STWDrainQueueClosure: public VoidClosure { 5249 protected: 5250 G1CollectedHeap* _g1h; 5251 G1ParScanThreadState* _par_scan_state; 5252 5253 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5254 5255 public: 5256 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5257 _g1h(g1h), 5258 _par_scan_state(pss) 5259 { } 5260 5261 void do_void() { 5262 G1ParScanThreadState* const pss = par_scan_state(); 5263 pss->trim_queue(); 5264 } 5265 }; 5266 5267 // Parallel Reference Processing closures 5268 5269 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5270 // processing during G1 evacuation pauses. 5271 5272 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5273 private: 5274 G1CollectedHeap* _g1h; 5275 RefToScanQueueSet* _queues; 5276 FlexibleWorkGang* _workers; 5277 int _active_workers; 5278 5279 public: 5280 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5281 FlexibleWorkGang* workers, 5282 RefToScanQueueSet *task_queues, 5283 int n_workers) : 5284 _g1h(g1h), 5285 _queues(task_queues), 5286 _workers(workers), 5287 _active_workers(n_workers) 5288 { 5289 assert(n_workers > 0, "shouldn't call this otherwise"); 5290 } 5291 5292 // Executes the given task using concurrent marking worker threads. 5293 virtual void execute(ProcessTask& task); 5294 virtual void execute(EnqueueTask& task); 5295 }; 5296 5297 // Gang task for possibly parallel reference processing 5298 5299 class G1STWRefProcTaskProxy: public AbstractGangTask { 5300 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5301 ProcessTask& _proc_task; 5302 G1CollectedHeap* _g1h; 5303 RefToScanQueueSet *_task_queues; 5304 ParallelTaskTerminator* _terminator; 5305 5306 public: 5307 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5308 G1CollectedHeap* g1h, 5309 RefToScanQueueSet *task_queues, 5310 ParallelTaskTerminator* terminator) : 5311 AbstractGangTask("Process reference objects in parallel"), 5312 _proc_task(proc_task), 5313 _g1h(g1h), 5314 _task_queues(task_queues), 5315 _terminator(terminator) 5316 {} 5317 5318 virtual void work(uint worker_id) { 5319 // The reference processing task executed by a single worker. 5320 ResourceMark rm; 5321 HandleMark hm; 5322 5323 G1STWIsAliveClosure is_alive(_g1h); 5324 5325 G1ParScanThreadState pss(_g1h, worker_id); 5326 5327 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL); 5328 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5329 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL); 5330 5331 pss.set_evac_closure(&scan_evac_cl); 5332 pss.set_evac_failure_closure(&evac_failure_cl); 5333 pss.set_partial_scan_closure(&partial_scan_cl); 5334 5335 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5336 G1ParScanPermClosure only_copy_perm_cl(_g1h, &pss, NULL); 5337 5338 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5339 G1ParScanAndMarkPermClosure copy_mark_perm_cl(_g1h, &pss, NULL); 5340 5341 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5342 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl; 5343 5344 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5345 // We also need to mark copied objects. 5346 copy_non_heap_cl = ©_mark_non_heap_cl; 5347 copy_perm_cl = ©_mark_perm_cl; 5348 } 5349 5350 // Keep alive closure. 5351 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss); 5352 5353 // Complete GC closure 5354 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5355 5356 // Call the reference processing task's work routine. 5357 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5358 5359 // Note we cannot assert that the refs array is empty here as not all 5360 // of the processing tasks (specifically phase2 - pp2_work) execute 5361 // the complete_gc closure (which ordinarily would drain the queue) so 5362 // the queue may not be empty. 5363 } 5364 }; 5365 5366 // Driver routine for parallel reference processing. 5367 // Creates an instance of the ref processing gang 5368 // task and has the worker threads execute it. 5369 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5370 assert(_workers != NULL, "Need parallel worker threads."); 5371 5372 ParallelTaskTerminator terminator(_active_workers, _queues); 5373 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5374 5375 _g1h->set_par_threads(_active_workers); 5376 _workers->run_task(&proc_task_proxy); 5377 _g1h->set_par_threads(0); 5378 } 5379 5380 // Gang task for parallel reference enqueueing. 5381 5382 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5383 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5384 EnqueueTask& _enq_task; 5385 5386 public: 5387 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5388 AbstractGangTask("Enqueue reference objects in parallel"), 5389 _enq_task(enq_task) 5390 { } 5391 5392 virtual void work(uint worker_id) { 5393 _enq_task.work(worker_id); 5394 } 5395 }; 5396 5397 // Driver routine for parallel reference enqueueing. 5398 // Creates an instance of the ref enqueueing gang 5399 // task and has the worker threads execute it. 5400 5401 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5402 assert(_workers != NULL, "Need parallel worker threads."); 5403 5404 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5405 5406 _g1h->set_par_threads(_active_workers); 5407 _workers->run_task(&enq_task_proxy); 5408 _g1h->set_par_threads(0); 5409 } 5410 5411 // End of weak reference support closures 5412 5413 // Abstract task used to preserve (i.e. copy) any referent objects 5414 // that are in the collection set and are pointed to by reference 5415 // objects discovered by the CM ref processor. 5416 5417 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5418 protected: 5419 G1CollectedHeap* _g1h; 5420 RefToScanQueueSet *_queues; 5421 ParallelTaskTerminator _terminator; 5422 uint _n_workers; 5423 5424 public: 5425 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5426 AbstractGangTask("ParPreserveCMReferents"), 5427 _g1h(g1h), 5428 _queues(task_queues), 5429 _terminator(workers, _queues), 5430 _n_workers(workers) 5431 { } 5432 5433 void work(uint worker_id) { 5434 ResourceMark rm; 5435 HandleMark hm; 5436 5437 G1ParScanThreadState pss(_g1h, worker_id); 5438 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL); 5439 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5440 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL); 5441 5442 pss.set_evac_closure(&scan_evac_cl); 5443 pss.set_evac_failure_closure(&evac_failure_cl); 5444 pss.set_partial_scan_closure(&partial_scan_cl); 5445 5446 assert(pss.refs()->is_empty(), "both queue and overflow should be empty"); 5447 5448 5449 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5450 G1ParScanPermClosure only_copy_perm_cl(_g1h, &pss, NULL); 5451 5452 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5453 G1ParScanAndMarkPermClosure copy_mark_perm_cl(_g1h, &pss, NULL); 5454 5455 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5456 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl; 5457 5458 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5459 // We also need to mark copied objects. 5460 copy_non_heap_cl = ©_mark_non_heap_cl; 5461 copy_perm_cl = ©_mark_perm_cl; 5462 } 5463 5464 // Is alive closure 5465 G1AlwaysAliveClosure always_alive(_g1h); 5466 5467 // Copying keep alive closure. Applied to referent objects that need 5468 // to be copied. 5469 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss); 5470 5471 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5472 5473 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5474 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5475 5476 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5477 // So this must be true - but assert just in case someone decides to 5478 // change the worker ids. 5479 assert(0 <= worker_id && worker_id < limit, "sanity"); 5480 assert(!rp->discovery_is_atomic(), "check this code"); 5481 5482 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5483 for (uint idx = worker_id; idx < limit; idx += stride) { 5484 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5485 5486 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5487 while (iter.has_next()) { 5488 // Since discovery is not atomic for the CM ref processor, we 5489 // can see some null referent objects. 5490 iter.load_ptrs(DEBUG_ONLY(true)); 5491 oop ref = iter.obj(); 5492 5493 // This will filter nulls. 5494 if (iter.is_referent_alive()) { 5495 iter.make_referent_alive(); 5496 } 5497 iter.move_to_next(); 5498 } 5499 } 5500 5501 // Drain the queue - which may cause stealing 5502 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5503 drain_queue.do_void(); 5504 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5505 assert(pss.refs()->is_empty(), "should be"); 5506 } 5507 }; 5508 5509 // Weak Reference processing during an evacuation pause (part 1). 5510 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5511 double ref_proc_start = os::elapsedTime(); 5512 5513 ReferenceProcessor* rp = _ref_processor_stw; 5514 assert(rp->discovery_enabled(), "should have been enabled"); 5515 5516 // Any reference objects, in the collection set, that were 'discovered' 5517 // by the CM ref processor should have already been copied (either by 5518 // applying the external root copy closure to the discovered lists, or 5519 // by following an RSet entry). 5520 // 5521 // But some of the referents, that are in the collection set, that these 5522 // reference objects point to may not have been copied: the STW ref 5523 // processor would have seen that the reference object had already 5524 // been 'discovered' and would have skipped discovering the reference, 5525 // but would not have treated the reference object as a regular oop. 5526 // As a result the copy closure would not have been applied to the 5527 // referent object. 5528 // 5529 // We need to explicitly copy these referent objects - the references 5530 // will be processed at the end of remarking. 5531 // 5532 // We also need to do this copying before we process the reference 5533 // objects discovered by the STW ref processor in case one of these 5534 // referents points to another object which is also referenced by an 5535 // object discovered by the STW ref processor. 5536 5537 assert(!G1CollectedHeap::use_parallel_gc_threads() || 5538 no_of_gc_workers == workers()->active_workers(), 5539 "Need to reset active GC workers"); 5540 5541 set_par_threads(no_of_gc_workers); 5542 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5543 no_of_gc_workers, 5544 _task_queues); 5545 5546 if (G1CollectedHeap::use_parallel_gc_threads()) { 5547 workers()->run_task(&keep_cm_referents); 5548 } else { 5549 keep_cm_referents.work(0); 5550 } 5551 5552 set_par_threads(0); 5553 5554 // Closure to test whether a referent is alive. 5555 G1STWIsAliveClosure is_alive(this); 5556 5557 // Even when parallel reference processing is enabled, the processing 5558 // of JNI refs is serial and performed serially by the current thread 5559 // rather than by a worker. The following PSS will be used for processing 5560 // JNI refs. 5561 5562 // Use only a single queue for this PSS. 5563 G1ParScanThreadState pss(this, 0); 5564 5565 // We do not embed a reference processor in the copying/scanning 5566 // closures while we're actually processing the discovered 5567 // reference objects. 5568 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL); 5569 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5570 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL); 5571 5572 pss.set_evac_closure(&scan_evac_cl); 5573 pss.set_evac_failure_closure(&evac_failure_cl); 5574 pss.set_partial_scan_closure(&partial_scan_cl); 5575 5576 assert(pss.refs()->is_empty(), "pre-condition"); 5577 5578 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5579 G1ParScanPermClosure only_copy_perm_cl(this, &pss, NULL); 5580 5581 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5582 G1ParScanAndMarkPermClosure copy_mark_perm_cl(this, &pss, NULL); 5583 5584 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5585 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl; 5586 5587 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5588 // We also need to mark copied objects. 5589 copy_non_heap_cl = ©_mark_non_heap_cl; 5590 copy_perm_cl = ©_mark_perm_cl; 5591 } 5592 5593 // Keep alive closure. 5594 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_perm_cl, &pss); 5595 5596 // Serial Complete GC closure 5597 G1STWDrainQueueClosure drain_queue(this, &pss); 5598 5599 // Setup the soft refs policy... 5600 rp->setup_policy(false); 5601 5602 ReferenceProcessorStats stats; 5603 if (!rp->processing_is_mt()) { 5604 // Serial reference processing... 5605 stats = rp->process_discovered_references(&is_alive, 5606 &keep_alive, 5607 &drain_queue, 5608 NULL, 5609 _gc_timer_stw); 5610 } else { 5611 // Parallel reference processing 5612 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5613 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5614 5615 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5616 stats = rp->process_discovered_references(&is_alive, 5617 &keep_alive, 5618 &drain_queue, 5619 &par_task_executor, 5620 _gc_timer_stw); 5621 } 5622 5623 _gc_tracer_stw->report_gc_reference_stats(stats); 5624 // We have completed copying any necessary live referent objects 5625 // (that were not copied during the actual pause) so we can 5626 // retire any active alloc buffers 5627 pss.retire_alloc_buffers(); 5628 assert(pss.refs()->is_empty(), "both queue and overflow should be empty"); 5629 5630 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5631 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5632 } 5633 5634 // Weak Reference processing during an evacuation pause (part 2). 5635 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5636 double ref_enq_start = os::elapsedTime(); 5637 5638 ReferenceProcessor* rp = _ref_processor_stw; 5639 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5640 5641 // Now enqueue any remaining on the discovered lists on to 5642 // the pending list. 5643 if (!rp->processing_is_mt()) { 5644 // Serial reference processing... 5645 rp->enqueue_discovered_references(); 5646 } else { 5647 // Parallel reference enqueueing 5648 5649 assert(no_of_gc_workers == workers()->active_workers(), 5650 "Need to reset active workers"); 5651 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5652 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5653 5654 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5655 rp->enqueue_discovered_references(&par_task_executor); 5656 } 5657 5658 rp->verify_no_references_recorded(); 5659 assert(!rp->discovery_enabled(), "should have been disabled"); 5660 5661 // FIXME 5662 // CM's reference processing also cleans up the string and symbol tables. 5663 // Should we do that here also? We could, but it is a serial operation 5664 // and could significantly increase the pause time. 5665 5666 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5667 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5668 } 5669 5670 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5671 _expand_heap_after_alloc_failure = true; 5672 _evacuation_failed = false; 5673 5674 // Should G1EvacuationFailureALot be in effect for this GC? 5675 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5676 5677 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5678 concurrent_g1_refine()->set_use_cache(false); 5679 concurrent_g1_refine()->clear_hot_cache_claimed_index(); 5680 5681 uint n_workers; 5682 if (G1CollectedHeap::use_parallel_gc_threads()) { 5683 n_workers = 5684 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 5685 workers()->active_workers(), 5686 Threads::number_of_non_daemon_threads()); 5687 assert(UseDynamicNumberOfGCThreads || 5688 n_workers == workers()->total_workers(), 5689 "If not dynamic should be using all the workers"); 5690 workers()->set_active_workers(n_workers); 5691 set_par_threads(n_workers); 5692 } else { 5693 assert(n_par_threads() == 0, 5694 "Should be the original non-parallel value"); 5695 n_workers = 1; 5696 } 5697 5698 G1ParTask g1_par_task(this, _task_queues); 5699 5700 init_for_evac_failure(NULL); 5701 5702 rem_set()->prepare_for_younger_refs_iterate(true); 5703 5704 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5705 double start_par_time_sec = os::elapsedTime(); 5706 double end_par_time_sec; 5707 5708 { 5709 StrongRootsScope srs(this); 5710 5711 if (G1CollectedHeap::use_parallel_gc_threads()) { 5712 // The individual threads will set their evac-failure closures. 5713 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr(); 5714 // These tasks use ShareHeap::_process_strong_tasks 5715 assert(UseDynamicNumberOfGCThreads || 5716 workers()->active_workers() == workers()->total_workers(), 5717 "If not dynamic should be using all the workers"); 5718 workers()->run_task(&g1_par_task); 5719 } else { 5720 g1_par_task.set_for_termination(n_workers); 5721 g1_par_task.work(0); 5722 } 5723 end_par_time_sec = os::elapsedTime(); 5724 5725 // Closing the inner scope will execute the destructor 5726 // for the StrongRootsScope object. We record the current 5727 // elapsed time before closing the scope so that time 5728 // taken for the SRS destructor is NOT included in the 5729 // reported parallel time. 5730 } 5731 5732 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5733 g1_policy()->phase_times()->record_par_time(par_time_ms); 5734 5735 double code_root_fixup_time_ms = 5736 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5737 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms); 5738 5739 set_par_threads(0); 5740 5741 // Process any discovered reference objects - we have 5742 // to do this _before_ we retire the GC alloc regions 5743 // as we may have to copy some 'reachable' referent 5744 // objects (and their reachable sub-graphs) that were 5745 // not copied during the pause. 5746 process_discovered_references(n_workers); 5747 5748 // Weak root processing. 5749 // Note: when JSR 292 is enabled and code blobs can contain 5750 // non-perm oops then we will need to process the code blobs 5751 // here too. 5752 { 5753 G1STWIsAliveClosure is_alive(this); 5754 G1KeepAliveClosure keep_alive(this); 5755 JNIHandles::weak_oops_do(&is_alive, &keep_alive); 5756 } 5757 5758 release_gc_alloc_regions(n_workers, evacuation_info); 5759 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5760 5761 concurrent_g1_refine()->clear_hot_cache(); 5762 concurrent_g1_refine()->set_use_cache(true); 5763 5764 finalize_for_evac_failure(); 5765 5766 if (evacuation_failed()) { 5767 remove_self_forwarding_pointers(); 5768 5769 // Reset the G1EvacuationFailureALot counters and flags 5770 // Note: the values are reset only when an actual 5771 // evacuation failure occurs. 5772 NOT_PRODUCT(reset_evacuation_should_fail();) 5773 } 5774 5775 // Enqueue any remaining references remaining on the STW 5776 // reference processor's discovered lists. We need to do 5777 // this after the card table is cleaned (and verified) as 5778 // the act of enqueueing entries on to the pending list 5779 // will log these updates (and dirty their associated 5780 // cards). We need these updates logged to update any 5781 // RSets. 5782 enqueue_discovered_references(n_workers); 5783 5784 if (G1DeferredRSUpdate) { 5785 RedirtyLoggedCardTableEntryFastClosure redirty; 5786 dirty_card_queue_set().set_closure(&redirty); 5787 dirty_card_queue_set().apply_closure_to_all_completed_buffers(); 5788 5789 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 5790 dcq.merge_bufferlists(&dirty_card_queue_set()); 5791 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 5792 } 5793 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5794 } 5795 5796 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr, 5797 size_t* pre_used, 5798 FreeRegionList* free_list, 5799 OldRegionSet* old_proxy_set, 5800 HumongousRegionSet* humongous_proxy_set, 5801 HRRSCleanupTask* hrrs_cleanup_task, 5802 bool par) { 5803 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) { 5804 if (hr->isHumongous()) { 5805 assert(hr->startsHumongous(), "we should only see starts humongous"); 5806 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par); 5807 } else { 5808 _old_set.remove_with_proxy(hr, old_proxy_set); 5809 free_region(hr, pre_used, free_list, par); 5810 } 5811 } else { 5812 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task); 5813 } 5814 } 5815 5816 void G1CollectedHeap::free_region(HeapRegion* hr, 5817 size_t* pre_used, 5818 FreeRegionList* free_list, 5819 bool par) { 5820 assert(!hr->isHumongous(), "this is only for non-humongous regions"); 5821 assert(!hr->is_empty(), "the region should not be empty"); 5822 assert(free_list != NULL, "pre-condition"); 5823 5824 *pre_used += hr->used(); 5825 hr->hr_clear(par, true /* clear_space */); 5826 free_list->add_as_head(hr); 5827 } 5828 5829 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5830 size_t* pre_used, 5831 FreeRegionList* free_list, 5832 HumongousRegionSet* humongous_proxy_set, 5833 bool par) { 5834 assert(hr->startsHumongous(), "this is only for starts humongous regions"); 5835 assert(free_list != NULL, "pre-condition"); 5836 assert(humongous_proxy_set != NULL, "pre-condition"); 5837 5838 size_t hr_used = hr->used(); 5839 size_t hr_capacity = hr->capacity(); 5840 size_t hr_pre_used = 0; 5841 _humongous_set.remove_with_proxy(hr, humongous_proxy_set); 5842 // We need to read this before we make the region non-humongous, 5843 // otherwise the information will be gone. 5844 uint last_index = hr->last_hc_index(); 5845 hr->set_notHumongous(); 5846 free_region(hr, &hr_pre_used, free_list, par); 5847 5848 uint i = hr->hrs_index() + 1; 5849 while (i < last_index) { 5850 HeapRegion* curr_hr = region_at(i); 5851 assert(curr_hr->continuesHumongous(), "invariant"); 5852 curr_hr->set_notHumongous(); 5853 free_region(curr_hr, &hr_pre_used, free_list, par); 5854 i += 1; 5855 } 5856 assert(hr_pre_used == hr_used, 5857 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" " 5858 "should be the same", hr_pre_used, hr_used)); 5859 *pre_used += hr_pre_used; 5860 } 5861 5862 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used, 5863 FreeRegionList* free_list, 5864 OldRegionSet* old_proxy_set, 5865 HumongousRegionSet* humongous_proxy_set, 5866 bool par) { 5867 if (pre_used > 0) { 5868 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL; 5869 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag); 5870 assert(_summary_bytes_used >= pre_used, 5871 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" " 5872 "should be >= pre_used: "SIZE_FORMAT, 5873 _summary_bytes_used, pre_used)); 5874 _summary_bytes_used -= pre_used; 5875 } 5876 if (free_list != NULL && !free_list->is_empty()) { 5877 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 5878 _free_list.add_as_head(free_list); 5879 } 5880 if (old_proxy_set != NULL && !old_proxy_set->is_empty()) { 5881 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5882 _old_set.update_from_proxy(old_proxy_set); 5883 } 5884 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) { 5885 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 5886 _humongous_set.update_from_proxy(humongous_proxy_set); 5887 } 5888 } 5889 5890 class G1ParCleanupCTTask : public AbstractGangTask { 5891 CardTableModRefBS* _ct_bs; 5892 G1CollectedHeap* _g1h; 5893 HeapRegion* volatile _su_head; 5894 public: 5895 G1ParCleanupCTTask(CardTableModRefBS* ct_bs, 5896 G1CollectedHeap* g1h) : 5897 AbstractGangTask("G1 Par Cleanup CT Task"), 5898 _ct_bs(ct_bs), _g1h(g1h) { } 5899 5900 void work(uint worker_id) { 5901 HeapRegion* r; 5902 while (r = _g1h->pop_dirty_cards_region()) { 5903 clear_cards(r); 5904 } 5905 } 5906 5907 void clear_cards(HeapRegion* r) { 5908 // Cards of the survivors should have already been dirtied. 5909 if (!r->is_survivor()) { 5910 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 5911 } 5912 } 5913 }; 5914 5915 #ifndef PRODUCT 5916 class G1VerifyCardTableCleanup: public HeapRegionClosure { 5917 G1CollectedHeap* _g1h; 5918 CardTableModRefBS* _ct_bs; 5919 public: 5920 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs) 5921 : _g1h(g1h), _ct_bs(ct_bs) { } 5922 virtual bool doHeapRegion(HeapRegion* r) { 5923 if (r->is_survivor()) { 5924 _g1h->verify_dirty_region(r); 5925 } else { 5926 _g1h->verify_not_dirty_region(r); 5927 } 5928 return false; 5929 } 5930 }; 5931 5932 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 5933 // All of the region should be clean. 5934 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set(); 5935 MemRegion mr(hr->bottom(), hr->end()); 5936 ct_bs->verify_not_dirty_region(mr); 5937 } 5938 5939 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 5940 // We cannot guarantee that [bottom(),end()] is dirty. Threads 5941 // dirty allocated blocks as they allocate them. The thread that 5942 // retires each region and replaces it with a new one will do a 5943 // maximal allocation to fill in [pre_dummy_top(),end()] but will 5944 // not dirty that area (one less thing to have to do while holding 5945 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 5946 // is dirty. 5947 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set(); 5948 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 5949 ct_bs->verify_dirty_region(mr); 5950 } 5951 5952 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 5953 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set(); 5954 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 5955 verify_dirty_region(hr); 5956 } 5957 } 5958 5959 void G1CollectedHeap::verify_dirty_young_regions() { 5960 verify_dirty_young_list(_young_list->first_region()); 5961 } 5962 #endif 5963 5964 void G1CollectedHeap::cleanUpCardTable() { 5965 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set()); 5966 double start = os::elapsedTime(); 5967 5968 { 5969 // Iterate over the dirty cards region list. 5970 G1ParCleanupCTTask cleanup_task(ct_bs, this); 5971 5972 if (G1CollectedHeap::use_parallel_gc_threads()) { 5973 set_par_threads(); 5974 workers()->run_task(&cleanup_task); 5975 set_par_threads(0); 5976 } else { 5977 while (_dirty_cards_region_list) { 5978 HeapRegion* r = _dirty_cards_region_list; 5979 cleanup_task.clear_cards(r); 5980 _dirty_cards_region_list = r->get_next_dirty_cards_region(); 5981 if (_dirty_cards_region_list == r) { 5982 // The last region. 5983 _dirty_cards_region_list = NULL; 5984 } 5985 r->set_next_dirty_cards_region(NULL); 5986 } 5987 } 5988 #ifndef PRODUCT 5989 if (G1VerifyCTCleanup || VerifyAfterGC) { 5990 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 5991 heap_region_iterate(&cleanup_verifier); 5992 } 5993 #endif 5994 } 5995 5996 double elapsed = os::elapsedTime() - start; 5997 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 5998 } 5999 6000 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 6001 size_t pre_used = 0; 6002 FreeRegionList local_free_list("Local List for CSet Freeing"); 6003 6004 double young_time_ms = 0.0; 6005 double non_young_time_ms = 0.0; 6006 6007 // Since the collection set is a superset of the the young list, 6008 // all we need to do to clear the young list is clear its 6009 // head and length, and unlink any young regions in the code below 6010 _young_list->clear(); 6011 6012 G1CollectorPolicy* policy = g1_policy(); 6013 6014 double start_sec = os::elapsedTime(); 6015 bool non_young = true; 6016 6017 HeapRegion* cur = cs_head; 6018 int age_bound = -1; 6019 size_t rs_lengths = 0; 6020 6021 while (cur != NULL) { 6022 assert(!is_on_master_free_list(cur), "sanity"); 6023 if (non_young) { 6024 if (cur->is_young()) { 6025 double end_sec = os::elapsedTime(); 6026 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6027 non_young_time_ms += elapsed_ms; 6028 6029 start_sec = os::elapsedTime(); 6030 non_young = false; 6031 } 6032 } else { 6033 if (!cur->is_young()) { 6034 double end_sec = os::elapsedTime(); 6035 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6036 young_time_ms += elapsed_ms; 6037 6038 start_sec = os::elapsedTime(); 6039 non_young = true; 6040 } 6041 } 6042 6043 rs_lengths += cur->rem_set()->occupied(); 6044 6045 HeapRegion* next = cur->next_in_collection_set(); 6046 assert(cur->in_collection_set(), "bad CS"); 6047 cur->set_next_in_collection_set(NULL); 6048 cur->set_in_collection_set(false); 6049 6050 if (cur->is_young()) { 6051 int index = cur->young_index_in_cset(); 6052 assert(index != -1, "invariant"); 6053 assert((uint) index < policy->young_cset_region_length(), "invariant"); 6054 size_t words_survived = _surviving_young_words[index]; 6055 cur->record_surv_words_in_group(words_survived); 6056 6057 // At this point the we have 'popped' cur from the collection set 6058 // (linked via next_in_collection_set()) but it is still in the 6059 // young list (linked via next_young_region()). Clear the 6060 // _next_young_region field. 6061 cur->set_next_young_region(NULL); 6062 } else { 6063 int index = cur->young_index_in_cset(); 6064 assert(index == -1, "invariant"); 6065 } 6066 6067 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 6068 (!cur->is_young() && cur->young_index_in_cset() == -1), 6069 "invariant" ); 6070 6071 if (!cur->evacuation_failed()) { 6072 MemRegion used_mr = cur->used_region(); 6073 6074 // And the region is empty. 6075 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 6076 free_region(cur, &pre_used, &local_free_list, false /* par */); 6077 } else { 6078 cur->uninstall_surv_rate_group(); 6079 if (cur->is_young()) { 6080 cur->set_young_index_in_cset(-1); 6081 } 6082 cur->set_not_young(); 6083 cur->set_evacuation_failed(false); 6084 // The region is now considered to be old. 6085 _old_set.add(cur); 6086 evacuation_info.increment_collectionset_used_after(cur->used()); 6087 } 6088 cur = next; 6089 } 6090 6091 evacuation_info.set_regions_freed(local_free_list.length()); 6092 policy->record_max_rs_lengths(rs_lengths); 6093 policy->cset_regions_freed(); 6094 6095 double end_sec = os::elapsedTime(); 6096 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6097 6098 if (non_young) { 6099 non_young_time_ms += elapsed_ms; 6100 } else { 6101 young_time_ms += elapsed_ms; 6102 } 6103 6104 update_sets_after_freeing_regions(pre_used, &local_free_list, 6105 NULL /* old_proxy_set */, 6106 NULL /* humongous_proxy_set */, 6107 false /* par */); 6108 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 6109 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 6110 } 6111 6112 // This routine is similar to the above but does not record 6113 // any policy statistics or update free lists; we are abandoning 6114 // the current incremental collection set in preparation of a 6115 // full collection. After the full GC we will start to build up 6116 // the incremental collection set again. 6117 // This is only called when we're doing a full collection 6118 // and is immediately followed by the tearing down of the young list. 6119 6120 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6121 HeapRegion* cur = cs_head; 6122 6123 while (cur != NULL) { 6124 HeapRegion* next = cur->next_in_collection_set(); 6125 assert(cur->in_collection_set(), "bad CS"); 6126 cur->set_next_in_collection_set(NULL); 6127 cur->set_in_collection_set(false); 6128 cur->set_young_index_in_cset(-1); 6129 cur = next; 6130 } 6131 } 6132 6133 void G1CollectedHeap::set_free_regions_coming() { 6134 if (G1ConcRegionFreeingVerbose) { 6135 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6136 "setting free regions coming"); 6137 } 6138 6139 assert(!free_regions_coming(), "pre-condition"); 6140 _free_regions_coming = true; 6141 } 6142 6143 void G1CollectedHeap::reset_free_regions_coming() { 6144 assert(free_regions_coming(), "pre-condition"); 6145 6146 { 6147 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6148 _free_regions_coming = false; 6149 SecondaryFreeList_lock->notify_all(); 6150 } 6151 6152 if (G1ConcRegionFreeingVerbose) { 6153 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6154 "reset free regions coming"); 6155 } 6156 } 6157 6158 void G1CollectedHeap::wait_while_free_regions_coming() { 6159 // Most of the time we won't have to wait, so let's do a quick test 6160 // first before we take the lock. 6161 if (!free_regions_coming()) { 6162 return; 6163 } 6164 6165 if (G1ConcRegionFreeingVerbose) { 6166 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6167 "waiting for free regions"); 6168 } 6169 6170 { 6171 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6172 while (free_regions_coming()) { 6173 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6174 } 6175 } 6176 6177 if (G1ConcRegionFreeingVerbose) { 6178 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6179 "done waiting for free regions"); 6180 } 6181 } 6182 6183 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6184 assert(heap_lock_held_for_gc(), 6185 "the heap lock should already be held by or for this thread"); 6186 _young_list->push_region(hr); 6187 } 6188 6189 class NoYoungRegionsClosure: public HeapRegionClosure { 6190 private: 6191 bool _success; 6192 public: 6193 NoYoungRegionsClosure() : _success(true) { } 6194 bool doHeapRegion(HeapRegion* r) { 6195 if (r->is_young()) { 6196 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6197 r->bottom(), r->end()); 6198 _success = false; 6199 } 6200 return false; 6201 } 6202 bool success() { return _success; } 6203 }; 6204 6205 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6206 bool ret = _young_list->check_list_empty(check_sample); 6207 6208 if (check_heap) { 6209 NoYoungRegionsClosure closure; 6210 heap_region_iterate(&closure); 6211 ret = ret && closure.success(); 6212 } 6213 6214 return ret; 6215 } 6216 6217 class TearDownRegionSetsClosure : public HeapRegionClosure { 6218 private: 6219 OldRegionSet *_old_set; 6220 6221 public: 6222 TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { } 6223 6224 bool doHeapRegion(HeapRegion* r) { 6225 if (r->is_empty()) { 6226 // We ignore empty regions, we'll empty the free list afterwards 6227 } else if (r->is_young()) { 6228 // We ignore young regions, we'll empty the young list afterwards 6229 } else if (r->isHumongous()) { 6230 // We ignore humongous regions, we're not tearing down the 6231 // humongous region set 6232 } else { 6233 // The rest should be old 6234 _old_set->remove(r); 6235 } 6236 return false; 6237 } 6238 6239 ~TearDownRegionSetsClosure() { 6240 assert(_old_set->is_empty(), "post-condition"); 6241 } 6242 }; 6243 6244 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6245 assert_at_safepoint(true /* should_be_vm_thread */); 6246 6247 if (!free_list_only) { 6248 TearDownRegionSetsClosure cl(&_old_set); 6249 heap_region_iterate(&cl); 6250 6251 // Need to do this after the heap iteration to be able to 6252 // recognize the young regions and ignore them during the iteration. 6253 _young_list->empty_list(); 6254 } 6255 _free_list.remove_all(); 6256 } 6257 6258 class RebuildRegionSetsClosure : public HeapRegionClosure { 6259 private: 6260 bool _free_list_only; 6261 OldRegionSet* _old_set; 6262 FreeRegionList* _free_list; 6263 size_t _total_used; 6264 6265 public: 6266 RebuildRegionSetsClosure(bool free_list_only, 6267 OldRegionSet* old_set, FreeRegionList* free_list) : 6268 _free_list_only(free_list_only), 6269 _old_set(old_set), _free_list(free_list), _total_used(0) { 6270 assert(_free_list->is_empty(), "pre-condition"); 6271 if (!free_list_only) { 6272 assert(_old_set->is_empty(), "pre-condition"); 6273 } 6274 } 6275 6276 bool doHeapRegion(HeapRegion* r) { 6277 if (r->continuesHumongous()) { 6278 return false; 6279 } 6280 6281 if (r->is_empty()) { 6282 // Add free regions to the free list 6283 _free_list->add_as_tail(r); 6284 } else if (!_free_list_only) { 6285 assert(!r->is_young(), "we should not come across young regions"); 6286 6287 if (r->isHumongous()) { 6288 // We ignore humongous regions, we left the humongous set unchanged 6289 } else { 6290 // The rest should be old, add them to the old set 6291 _old_set->add(r); 6292 } 6293 _total_used += r->used(); 6294 } 6295 6296 return false; 6297 } 6298 6299 size_t total_used() { 6300 return _total_used; 6301 } 6302 }; 6303 6304 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6305 assert_at_safepoint(true /* should_be_vm_thread */); 6306 6307 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list); 6308 heap_region_iterate(&cl); 6309 6310 if (!free_list_only) { 6311 _summary_bytes_used = cl.total_used(); 6312 } 6313 assert(_summary_bytes_used == recalculate_used(), 6314 err_msg("inconsistent _summary_bytes_used, " 6315 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6316 _summary_bytes_used, recalculate_used())); 6317 } 6318 6319 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6320 _refine_cte_cl->set_concurrent(concurrent); 6321 } 6322 6323 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6324 HeapRegion* hr = heap_region_containing(p); 6325 if (hr == NULL) { 6326 return is_in_permanent(p); 6327 } else { 6328 return hr->is_in(p); 6329 } 6330 } 6331 6332 // Methods for the mutator alloc region 6333 6334 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6335 bool force) { 6336 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6337 assert(!force || g1_policy()->can_expand_young_list(), 6338 "if force is true we should be able to expand the young list"); 6339 bool young_list_full = g1_policy()->is_young_list_full(); 6340 if (force || !young_list_full) { 6341 HeapRegion* new_alloc_region = new_region(word_size, 6342 false /* do_expand */); 6343 if (new_alloc_region != NULL) { 6344 set_region_short_lived_locked(new_alloc_region); 6345 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6346 return new_alloc_region; 6347 } 6348 } 6349 return NULL; 6350 } 6351 6352 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6353 size_t allocated_bytes) { 6354 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6355 assert(alloc_region->is_young(), "all mutator alloc regions should be young"); 6356 6357 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6358 _summary_bytes_used += allocated_bytes; 6359 _hr_printer.retire(alloc_region); 6360 // We update the eden sizes here, when the region is retired, 6361 // instead of when it's allocated, since this is the point that its 6362 // used space has been recored in _summary_bytes_used. 6363 g1mm()->update_eden_size(); 6364 } 6365 6366 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size, 6367 bool force) { 6368 return _g1h->new_mutator_alloc_region(word_size, force); 6369 } 6370 6371 void G1CollectedHeap::set_par_threads() { 6372 // Don't change the number of workers. Use the value previously set 6373 // in the workgroup. 6374 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise"); 6375 uint n_workers = workers()->active_workers(); 6376 assert(UseDynamicNumberOfGCThreads || 6377 n_workers == workers()->total_workers(), 6378 "Otherwise should be using the total number of workers"); 6379 if (n_workers == 0) { 6380 assert(false, "Should have been set in prior evacuation pause."); 6381 n_workers = ParallelGCThreads; 6382 workers()->set_active_workers(n_workers); 6383 } 6384 set_par_threads(n_workers); 6385 } 6386 6387 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region, 6388 size_t allocated_bytes) { 6389 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes); 6390 } 6391 6392 // Methods for the GC alloc regions 6393 6394 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6395 uint count, 6396 GCAllocPurpose ap) { 6397 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6398 6399 if (count < g1_policy()->max_regions(ap)) { 6400 HeapRegion* new_alloc_region = new_region(word_size, 6401 true /* do_expand */); 6402 if (new_alloc_region != NULL) { 6403 // We really only need to do this for old regions given that we 6404 // should never scan survivors. But it doesn't hurt to do it 6405 // for survivors too. 6406 new_alloc_region->set_saved_mark(); 6407 if (ap == GCAllocForSurvived) { 6408 new_alloc_region->set_survivor(); 6409 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6410 } else { 6411 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6412 } 6413 bool during_im = g1_policy()->during_initial_mark_pause(); 6414 new_alloc_region->note_start_of_copying(during_im); 6415 return new_alloc_region; 6416 } else { 6417 g1_policy()->note_alloc_region_limit_reached(ap); 6418 } 6419 } 6420 return NULL; 6421 } 6422 6423 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6424 size_t allocated_bytes, 6425 GCAllocPurpose ap) { 6426 bool during_im = g1_policy()->during_initial_mark_pause(); 6427 alloc_region->note_end_of_copying(during_im); 6428 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6429 if (ap == GCAllocForSurvived) { 6430 young_list()->add_survivor_region(alloc_region); 6431 } else { 6432 _old_set.add(alloc_region); 6433 } 6434 _hr_printer.retire(alloc_region); 6435 } 6436 6437 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size, 6438 bool force) { 6439 assert(!force, "not supported for GC alloc regions"); 6440 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived); 6441 } 6442 6443 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region, 6444 size_t allocated_bytes) { 6445 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6446 GCAllocForSurvived); 6447 } 6448 6449 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size, 6450 bool force) { 6451 assert(!force, "not supported for GC alloc regions"); 6452 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured); 6453 } 6454 6455 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region, 6456 size_t allocated_bytes) { 6457 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6458 GCAllocForTenured); 6459 } 6460 // Heap region set verification 6461 6462 class VerifyRegionListsClosure : public HeapRegionClosure { 6463 private: 6464 FreeRegionList* _free_list; 6465 OldRegionSet* _old_set; 6466 HumongousRegionSet* _humongous_set; 6467 uint _region_count; 6468 6469 public: 6470 VerifyRegionListsClosure(OldRegionSet* old_set, 6471 HumongousRegionSet* humongous_set, 6472 FreeRegionList* free_list) : 6473 _old_set(old_set), _humongous_set(humongous_set), 6474 _free_list(free_list), _region_count(0) { } 6475 6476 uint region_count() { return _region_count; } 6477 6478 bool doHeapRegion(HeapRegion* hr) { 6479 _region_count += 1; 6480 6481 if (hr->continuesHumongous()) { 6482 return false; 6483 } 6484 6485 if (hr->is_young()) { 6486 // TODO 6487 } else if (hr->startsHumongous()) { 6488 _humongous_set->verify_next_region(hr); 6489 } else if (hr->is_empty()) { 6490 _free_list->verify_next_region(hr); 6491 } else { 6492 _old_set->verify_next_region(hr); 6493 } 6494 return false; 6495 } 6496 }; 6497 6498 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 6499 HeapWord* bottom) { 6500 HeapWord* end = bottom + HeapRegion::GrainWords; 6501 MemRegion mr(bottom, end); 6502 assert(_g1_reserved.contains(mr), "invariant"); 6503 // This might return NULL if the allocation fails 6504 return new HeapRegion(hrs_index, _bot_shared, mr, true /* is_zeroed */); 6505 } 6506 6507 void G1CollectedHeap::verify_region_sets() { 6508 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6509 6510 // First, check the explicit lists. 6511 _free_list.verify(); 6512 { 6513 // Given that a concurrent operation might be adding regions to 6514 // the secondary free list we have to take the lock before 6515 // verifying it. 6516 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6517 _secondary_free_list.verify(); 6518 } 6519 _old_set.verify(); 6520 _humongous_set.verify(); 6521 6522 // If a concurrent region freeing operation is in progress it will 6523 // be difficult to correctly attributed any free regions we come 6524 // across to the correct free list given that they might belong to 6525 // one of several (free_list, secondary_free_list, any local lists, 6526 // etc.). So, if that's the case we will skip the rest of the 6527 // verification operation. Alternatively, waiting for the concurrent 6528 // operation to complete will have a non-trivial effect on the GC's 6529 // operation (no concurrent operation will last longer than the 6530 // interval between two calls to verification) and it might hide 6531 // any issues that we would like to catch during testing. 6532 if (free_regions_coming()) { 6533 return; 6534 } 6535 6536 // Make sure we append the secondary_free_list on the free_list so 6537 // that all free regions we will come across can be safely 6538 // attributed to the free_list. 6539 append_secondary_free_list_if_not_empty_with_lock(); 6540 6541 // Finally, make sure that the region accounting in the lists is 6542 // consistent with what we see in the heap. 6543 _old_set.verify_start(); 6544 _humongous_set.verify_start(); 6545 _free_list.verify_start(); 6546 6547 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list); 6548 heap_region_iterate(&cl); 6549 6550 _old_set.verify_end(); 6551 _humongous_set.verify_end(); 6552 _free_list.verify_end(); 6553 }