1 /* 2 * Copyright (c) 2001, 2014, 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/codeCache.hpp" 27 #include "code/icBuffer.hpp" 28 #include "gc_implementation/g1/bufferingOopClosure.hpp" 29 #include "gc_implementation/g1/concurrentG1Refine.hpp" 30 #include "gc_implementation/g1/concurrentG1RefineThread.hpp" 31 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 32 #include "gc_implementation/g1/g1AllocRegion.inline.hpp" 33 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 34 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 35 #include "gc_implementation/g1/g1ErgoVerbose.hpp" 36 #include "gc_implementation/g1/g1EvacFailure.hpp" 37 #include "gc_implementation/g1/g1GCPhaseTimes.hpp" 38 #include "gc_implementation/g1/g1Log.hpp" 39 #include "gc_implementation/g1/g1MarkSweep.hpp" 40 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 41 #include "gc_implementation/g1/g1RemSet.inline.hpp" 42 #include "gc_implementation/g1/g1StringDedup.hpp" 43 #include "gc_implementation/g1/g1YCTypes.hpp" 44 #include "gc_implementation/g1/heapRegion.inline.hpp" 45 #include "gc_implementation/g1/heapRegionRemSet.hpp" 46 #include "gc_implementation/g1/heapRegionSeq.inline.hpp" 47 #include "gc_implementation/g1/vm_operations_g1.hpp" 48 #include "gc_implementation/shared/gcHeapSummary.hpp" 49 #include "gc_implementation/shared/gcTimer.hpp" 50 #include "gc_implementation/shared/gcTrace.hpp" 51 #include "gc_implementation/shared/gcTraceTime.hpp" 52 #include "gc_implementation/shared/isGCActiveMark.hpp" 53 #include "memory/gcLocker.inline.hpp" 54 #include "memory/generationSpec.hpp" 55 #include "memory/iterator.hpp" 56 #include "memory/referenceProcessor.hpp" 57 #include "oops/oop.inline.hpp" 58 #include "oops/oop.pcgc.inline.hpp" 59 #include "runtime/vmThread.hpp" 60 #include "utilities/ticks.hpp" 61 62 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 63 64 // turn it on so that the contents of the young list (scan-only / 65 // to-be-collected) are printed at "strategic" points before / during 66 // / after the collection --- this is useful for debugging 67 #define YOUNG_LIST_VERBOSE 0 68 // CURRENT STATUS 69 // This file is under construction. Search for "FIXME". 70 71 // INVARIANTS/NOTES 72 // 73 // All allocation activity covered by the G1CollectedHeap interface is 74 // serialized by acquiring the HeapLock. This happens in mem_allocate 75 // and allocate_new_tlab, which are the "entry" points to the 76 // allocation code from the rest of the JVM. (Note that this does not 77 // apply to TLAB allocation, which is not part of this interface: it 78 // is done by clients of this interface.) 79 80 // Notes on implementation of parallelism in different tasks. 81 // 82 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism. 83 // The number of GC workers is passed to heap_region_par_iterate_chunked(). 84 // It does use run_task() which sets _n_workers in the task. 85 // G1ParTask executes g1_process_strong_roots() -> 86 // SharedHeap::process_strong_roots() which calls eventually to 87 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses 88 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also 89 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap). 90 // 91 92 // Local to this file. 93 94 class RefineCardTableEntryClosure: public CardTableEntryClosure { 95 bool _concurrent; 96 public: 97 RefineCardTableEntryClosure() : _concurrent(true) { } 98 99 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 100 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); 101 // This path is executed by the concurrent refine or mutator threads, 102 // concurrently, and so we do not care if card_ptr contains references 103 // that point into the collection set. 104 assert(!oops_into_cset, "should be"); 105 106 if (_concurrent && SuspendibleThreadSet::should_yield()) { 107 // Caller will actually yield. 108 return false; 109 } 110 // Otherwise, we finished successfully; return true. 111 return true; 112 } 113 114 void set_concurrent(bool b) { _concurrent = b; } 115 }; 116 117 118 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure { 119 int _calls; 120 G1CollectedHeap* _g1h; 121 CardTableModRefBS* _ctbs; 122 int _histo[256]; 123 public: 124 ClearLoggedCardTableEntryClosure() : 125 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set()) 126 { 127 for (int i = 0; i < 256; i++) _histo[i] = 0; 128 } 129 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 130 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) { 131 _calls++; 132 unsigned char* ujb = (unsigned char*)card_ptr; 133 int ind = (int)(*ujb); 134 _histo[ind]++; 135 *card_ptr = -1; 136 } 137 return true; 138 } 139 int calls() { return _calls; } 140 void print_histo() { 141 gclog_or_tty->print_cr("Card table value histogram:"); 142 for (int i = 0; i < 256; i++) { 143 if (_histo[i] != 0) { 144 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]); 145 } 146 } 147 } 148 }; 149 150 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure { 151 int _calls; 152 G1CollectedHeap* _g1h; 153 CardTableModRefBS* _ctbs; 154 public: 155 RedirtyLoggedCardTableEntryClosure() : 156 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set()) {} 157 158 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 159 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) { 160 _calls++; 161 *card_ptr = 0; 162 } 163 return true; 164 } 165 int calls() { return _calls; } 166 }; 167 168 YoungList::YoungList(G1CollectedHeap* g1h) : 169 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), 170 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { 171 guarantee(check_list_empty(false), "just making sure..."); 172 } 173 174 void YoungList::push_region(HeapRegion *hr) { 175 assert(!hr->is_young(), "should not already be young"); 176 assert(hr->get_next_young_region() == NULL, "cause it should!"); 177 178 hr->set_next_young_region(_head); 179 _head = hr; 180 181 _g1h->g1_policy()->set_region_eden(hr, (int) _length); 182 ++_length; 183 } 184 185 void YoungList::add_survivor_region(HeapRegion* hr) { 186 assert(hr->is_survivor(), "should be flagged as survivor region"); 187 assert(hr->get_next_young_region() == NULL, "cause it should!"); 188 189 hr->set_next_young_region(_survivor_head); 190 if (_survivor_head == NULL) { 191 _survivor_tail = hr; 192 } 193 _survivor_head = hr; 194 ++_survivor_length; 195 } 196 197 void YoungList::empty_list(HeapRegion* list) { 198 while (list != NULL) { 199 HeapRegion* next = list->get_next_young_region(); 200 list->set_next_young_region(NULL); 201 list->uninstall_surv_rate_group(); 202 list->set_not_young(); 203 list = next; 204 } 205 } 206 207 void YoungList::empty_list() { 208 assert(check_list_well_formed(), "young list should be well formed"); 209 210 empty_list(_head); 211 _head = NULL; 212 _length = 0; 213 214 empty_list(_survivor_head); 215 _survivor_head = NULL; 216 _survivor_tail = NULL; 217 _survivor_length = 0; 218 219 _last_sampled_rs_lengths = 0; 220 221 assert(check_list_empty(false), "just making sure..."); 222 } 223 224 bool YoungList::check_list_well_formed() { 225 bool ret = true; 226 227 uint length = 0; 228 HeapRegion* curr = _head; 229 HeapRegion* last = NULL; 230 while (curr != NULL) { 231 if (!curr->is_young()) { 232 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " 233 "incorrectly tagged (y: %d, surv: %d)", 234 curr->bottom(), curr->end(), 235 curr->is_young(), curr->is_survivor()); 236 ret = false; 237 } 238 ++length; 239 last = curr; 240 curr = curr->get_next_young_region(); 241 } 242 ret = ret && (length == _length); 243 244 if (!ret) { 245 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); 246 gclog_or_tty->print_cr("### list has %u entries, _length is %u", 247 length, _length); 248 } 249 250 return ret; 251 } 252 253 bool YoungList::check_list_empty(bool check_sample) { 254 bool ret = true; 255 256 if (_length != 0) { 257 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", 258 _length); 259 ret = false; 260 } 261 if (check_sample && _last_sampled_rs_lengths != 0) { 262 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); 263 ret = false; 264 } 265 if (_head != NULL) { 266 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); 267 ret = false; 268 } 269 if (!ret) { 270 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); 271 } 272 273 return ret; 274 } 275 276 void 277 YoungList::rs_length_sampling_init() { 278 _sampled_rs_lengths = 0; 279 _curr = _head; 280 } 281 282 bool 283 YoungList::rs_length_sampling_more() { 284 return _curr != NULL; 285 } 286 287 void 288 YoungList::rs_length_sampling_next() { 289 assert( _curr != NULL, "invariant" ); 290 size_t rs_length = _curr->rem_set()->occupied(); 291 292 _sampled_rs_lengths += rs_length; 293 294 // The current region may not yet have been added to the 295 // incremental collection set (it gets added when it is 296 // retired as the current allocation region). 297 if (_curr->in_collection_set()) { 298 // Update the collection set policy information for this region 299 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); 300 } 301 302 _curr = _curr->get_next_young_region(); 303 if (_curr == NULL) { 304 _last_sampled_rs_lengths = _sampled_rs_lengths; 305 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); 306 } 307 } 308 309 void 310 YoungList::reset_auxilary_lists() { 311 guarantee( is_empty(), "young list should be empty" ); 312 assert(check_list_well_formed(), "young list should be well formed"); 313 314 // Add survivor regions to SurvRateGroup. 315 _g1h->g1_policy()->note_start_adding_survivor_regions(); 316 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); 317 318 int young_index_in_cset = 0; 319 for (HeapRegion* curr = _survivor_head; 320 curr != NULL; 321 curr = curr->get_next_young_region()) { 322 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); 323 324 // The region is a non-empty survivor so let's add it to 325 // the incremental collection set for the next evacuation 326 // pause. 327 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); 328 young_index_in_cset += 1; 329 } 330 assert((uint) young_index_in_cset == _survivor_length, "post-condition"); 331 _g1h->g1_policy()->note_stop_adding_survivor_regions(); 332 333 _head = _survivor_head; 334 _length = _survivor_length; 335 if (_survivor_head != NULL) { 336 assert(_survivor_tail != NULL, "cause it shouldn't be"); 337 assert(_survivor_length > 0, "invariant"); 338 _survivor_tail->set_next_young_region(NULL); 339 } 340 341 // Don't clear the survivor list handles until the start of 342 // the next evacuation pause - we need it in order to re-tag 343 // the survivor regions from this evacuation pause as 'young' 344 // at the start of the next. 345 346 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); 347 348 assert(check_list_well_formed(), "young list should be well formed"); 349 } 350 351 void YoungList::print() { 352 HeapRegion* lists[] = {_head, _survivor_head}; 353 const char* names[] = {"YOUNG", "SURVIVOR"}; 354 355 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) { 356 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); 357 HeapRegion *curr = lists[list]; 358 if (curr == NULL) 359 gclog_or_tty->print_cr(" empty"); 360 while (curr != NULL) { 361 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d", 362 HR_FORMAT_PARAMS(curr), 363 curr->prev_top_at_mark_start(), 364 curr->next_top_at_mark_start(), 365 curr->age_in_surv_rate_group_cond()); 366 curr = curr->get_next_young_region(); 367 } 368 } 369 370 gclog_or_tty->print_cr(""); 371 } 372 373 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) 374 { 375 // Claim the right to put the region on the dirty cards region list 376 // by installing a self pointer. 377 HeapRegion* next = hr->get_next_dirty_cards_region(); 378 if (next == NULL) { 379 HeapRegion* res = (HeapRegion*) 380 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), 381 NULL); 382 if (res == NULL) { 383 HeapRegion* head; 384 do { 385 // Put the region to the dirty cards region list. 386 head = _dirty_cards_region_list; 387 next = (HeapRegion*) 388 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); 389 if (next == head) { 390 assert(hr->get_next_dirty_cards_region() == hr, 391 "hr->get_next_dirty_cards_region() != hr"); 392 if (next == NULL) { 393 // The last region in the list points to itself. 394 hr->set_next_dirty_cards_region(hr); 395 } else { 396 hr->set_next_dirty_cards_region(next); 397 } 398 } 399 } while (next != head); 400 } 401 } 402 } 403 404 HeapRegion* G1CollectedHeap::pop_dirty_cards_region() 405 { 406 HeapRegion* head; 407 HeapRegion* hr; 408 do { 409 head = _dirty_cards_region_list; 410 if (head == NULL) { 411 return NULL; 412 } 413 HeapRegion* new_head = head->get_next_dirty_cards_region(); 414 if (head == new_head) { 415 // The last region. 416 new_head = NULL; 417 } 418 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, 419 head); 420 } while (hr != head); 421 assert(hr != NULL, "invariant"); 422 hr->set_next_dirty_cards_region(NULL); 423 return hr; 424 } 425 426 void G1CollectedHeap::stop_conc_gc_threads() { 427 _cg1r->stop(); 428 _cmThread->stop(); 429 if (G1StringDedup::is_enabled()) { 430 G1StringDedup::stop(); 431 } 432 } 433 434 #ifdef ASSERT 435 // A region is added to the collection set as it is retired 436 // so an address p can point to a region which will be in the 437 // collection set but has not yet been retired. This method 438 // therefore is only accurate during a GC pause after all 439 // regions have been retired. It is used for debugging 440 // to check if an nmethod has references to objects that can 441 // be move during a partial collection. Though it can be 442 // inaccurate, it is sufficient for G1 because the conservative 443 // implementation of is_scavengable() for G1 will indicate that 444 // all nmethods must be scanned during a partial collection. 445 bool G1CollectedHeap::is_in_partial_collection(const void* p) { 446 HeapRegion* hr = heap_region_containing(p); 447 return hr != NULL && hr->in_collection_set(); 448 } 449 #endif 450 451 // Returns true if the reference points to an object that 452 // can move in an incremental collection. 453 bool G1CollectedHeap::is_scavengable(const void* p) { 454 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 455 G1CollectorPolicy* g1p = g1h->g1_policy(); 456 HeapRegion* hr = heap_region_containing(p); 457 if (hr == NULL) { 458 // null 459 assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p)); 460 return false; 461 } else { 462 return !hr->isHumongous(); 463 } 464 } 465 466 void G1CollectedHeap::check_ct_logs_at_safepoint() { 467 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 468 CardTableModRefBS* ct_bs = g1_barrier_set(); 469 470 // Count the dirty cards at the start. 471 CountNonCleanMemRegionClosure count1(this); 472 ct_bs->mod_card_iterate(&count1); 473 int orig_count = count1.n(); 474 475 // First clear the logged cards. 476 ClearLoggedCardTableEntryClosure clear; 477 dcqs.apply_closure_to_all_completed_buffers(&clear); 478 dcqs.iterate_closure_all_threads(&clear, false); 479 clear.print_histo(); 480 481 // Now ensure that there's no dirty cards. 482 CountNonCleanMemRegionClosure count2(this); 483 ct_bs->mod_card_iterate(&count2); 484 if (count2.n() != 0) { 485 gclog_or_tty->print_cr("Card table has %d entries; %d originally", 486 count2.n(), orig_count); 487 } 488 guarantee(count2.n() == 0, "Card table should be clean."); 489 490 RedirtyLoggedCardTableEntryClosure redirty; 491 dcqs.apply_closure_to_all_completed_buffers(&redirty); 492 dcqs.iterate_closure_all_threads(&redirty, false); 493 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.", 494 clear.calls(), orig_count); 495 guarantee(redirty.calls() == clear.calls(), 496 "Or else mechanism is broken."); 497 498 CountNonCleanMemRegionClosure count3(this); 499 ct_bs->mod_card_iterate(&count3); 500 if (count3.n() != orig_count) { 501 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.", 502 orig_count, count3.n()); 503 guarantee(count3.n() >= orig_count, "Should have restored them all."); 504 } 505 } 506 507 // Private class members. 508 509 G1CollectedHeap* G1CollectedHeap::_g1h; 510 511 // Private methods. 512 513 HeapRegion* 514 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { 515 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 516 while (!_secondary_free_list.is_empty() || free_regions_coming()) { 517 if (!_secondary_free_list.is_empty()) { 518 if (G1ConcRegionFreeingVerbose) { 519 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 520 "secondary_free_list has %u entries", 521 _secondary_free_list.length()); 522 } 523 // It looks as if there are free regions available on the 524 // secondary_free_list. Let's move them to the free_list and try 525 // again to allocate from it. 526 append_secondary_free_list(); 527 528 assert(!_free_list.is_empty(), "if the secondary_free_list was not " 529 "empty we should have moved at least one entry to the free_list"); 530 HeapRegion* res = _free_list.remove_region(is_old); 531 if (G1ConcRegionFreeingVerbose) { 532 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 533 "allocated "HR_FORMAT" from secondary_free_list", 534 HR_FORMAT_PARAMS(res)); 535 } 536 return res; 537 } 538 539 // Wait here until we get notified either when (a) there are no 540 // more free regions coming or (b) some regions have been moved on 541 // the secondary_free_list. 542 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 543 } 544 545 if (G1ConcRegionFreeingVerbose) { 546 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 547 "could not allocate from secondary_free_list"); 548 } 549 return NULL; 550 } 551 552 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 553 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords, 554 "the only time we use this to allocate a humongous region is " 555 "when we are allocating a single humongous region"); 556 557 HeapRegion* res; 558 if (G1StressConcRegionFreeing) { 559 if (!_secondary_free_list.is_empty()) { 560 if (G1ConcRegionFreeingVerbose) { 561 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 562 "forced to look at the secondary_free_list"); 563 } 564 res = new_region_try_secondary_free_list(is_old); 565 if (res != NULL) { 566 return res; 567 } 568 } 569 } 570 571 res = _free_list.remove_region(is_old); 572 573 if (res == NULL) { 574 if (G1ConcRegionFreeingVerbose) { 575 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " 576 "res == NULL, trying the secondary_free_list"); 577 } 578 res = new_region_try_secondary_free_list(is_old); 579 } 580 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 581 // Currently, only attempts to allocate GC alloc regions set 582 // do_expand to true. So, we should only reach here during a 583 // safepoint. If this assumption changes we might have to 584 // reconsider the use of _expand_heap_after_alloc_failure. 585 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 586 587 ergo_verbose1(ErgoHeapSizing, 588 "attempt heap expansion", 589 ergo_format_reason("region allocation request failed") 590 ergo_format_byte("allocation request"), 591 word_size * HeapWordSize); 592 if (expand(word_size * HeapWordSize)) { 593 // Given that expand() succeeded in expanding the heap, and we 594 // always expand the heap by an amount aligned to the heap 595 // region size, the free list should in theory not be empty. 596 // In either case remove_region() will check for NULL. 597 res = _free_list.remove_region(is_old); 598 } else { 599 _expand_heap_after_alloc_failure = false; 600 } 601 } 602 return res; 603 } 604 605 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions, 606 size_t word_size) { 607 assert(isHumongous(word_size), "word_size should be humongous"); 608 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 609 610 uint first = G1_NULL_HRS_INDEX; 611 if (num_regions == 1) { 612 // Only one region to allocate, no need to go through the slower 613 // path. The caller will attempt the expansion if this fails, so 614 // let's not try to expand here too. 615 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 616 if (hr != NULL) { 617 first = hr->hrs_index(); 618 } else { 619 first = G1_NULL_HRS_INDEX; 620 } 621 } else { 622 // We can't allocate humongous regions while cleanupComplete() is 623 // running, since some of the regions we find to be empty might not 624 // yet be added to the free list and it is not straightforward to 625 // know which list they are on so that we can remove them. Note 626 // that we only need to do this if we need to allocate more than 627 // one region to satisfy the current humongous allocation 628 // request. If we are only allocating one region we use the common 629 // region allocation code (see above). 630 wait_while_free_regions_coming(); 631 append_secondary_free_list_if_not_empty_with_lock(); 632 633 if (free_regions() >= num_regions) { 634 first = _hrs.find_contiguous(num_regions); 635 if (first != G1_NULL_HRS_INDEX) { 636 for (uint i = first; i < first + num_regions; ++i) { 637 HeapRegion* hr = region_at(i); 638 assert(hr->is_empty(), "sanity"); 639 assert(is_on_master_free_list(hr), "sanity"); 640 hr->set_pending_removal(true); 641 } 642 _free_list.remove_all_pending(num_regions); 643 } 644 } 645 } 646 return first; 647 } 648 649 HeapWord* 650 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 651 uint num_regions, 652 size_t word_size) { 653 assert(first != G1_NULL_HRS_INDEX, "pre-condition"); 654 assert(isHumongous(word_size), "word_size should be humongous"); 655 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 656 657 // Index of last region in the series + 1. 658 uint last = first + num_regions; 659 660 // We need to initialize the region(s) we just discovered. This is 661 // a bit tricky given that it can happen concurrently with 662 // refinement threads refining cards on these regions and 663 // potentially wanting to refine the BOT as they are scanning 664 // those cards (this can happen shortly after a cleanup; see CR 665 // 6991377). So we have to set up the region(s) carefully and in 666 // a specific order. 667 668 // The word size sum of all the regions we will allocate. 669 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 670 assert(word_size <= word_size_sum, "sanity"); 671 672 // This will be the "starts humongous" region. 673 HeapRegion* first_hr = region_at(first); 674 // The header of the new object will be placed at the bottom of 675 // the first region. 676 HeapWord* new_obj = first_hr->bottom(); 677 // This will be the new end of the first region in the series that 678 // should also match the end of the last region in the series. 679 HeapWord* new_end = new_obj + word_size_sum; 680 // This will be the new top of the first region that will reflect 681 // this allocation. 682 HeapWord* new_top = new_obj + word_size; 683 684 // First, we need to zero the header of the space that we will be 685 // allocating. When we update top further down, some refinement 686 // threads might try to scan the region. By zeroing the header we 687 // ensure that any thread that will try to scan the region will 688 // come across the zero klass word and bail out. 689 // 690 // NOTE: It would not have been correct to have used 691 // CollectedHeap::fill_with_object() and make the space look like 692 // an int array. The thread that is doing the allocation will 693 // later update the object header to a potentially different array 694 // type and, for a very short period of time, the klass and length 695 // fields will be inconsistent. This could cause a refinement 696 // thread to calculate the object size incorrectly. 697 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 698 699 // We will set up the first region as "starts humongous". This 700 // will also update the BOT covering all the regions to reflect 701 // that there is a single object that starts at the bottom of the 702 // first region. 703 first_hr->set_startsHumongous(new_top, new_end); 704 705 // Then, if there are any, we will set up the "continues 706 // humongous" regions. 707 HeapRegion* hr = NULL; 708 for (uint i = first + 1; i < last; ++i) { 709 hr = region_at(i); 710 hr->set_continuesHumongous(first_hr); 711 } 712 // If we have "continues humongous" regions (hr != NULL), then the 713 // end of the last one should match new_end. 714 assert(hr == NULL || hr->end() == new_end, "sanity"); 715 716 // Up to this point no concurrent thread would have been able to 717 // do any scanning on any region in this series. All the top 718 // fields still point to bottom, so the intersection between 719 // [bottom,top] and [card_start,card_end] will be empty. Before we 720 // update the top fields, we'll do a storestore to make sure that 721 // no thread sees the update to top before the zeroing of the 722 // object header and the BOT initialization. 723 OrderAccess::storestore(); 724 725 // Now that the BOT and the object header have been initialized, 726 // we can update top of the "starts humongous" region. 727 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), 728 "new_top should be in this region"); 729 first_hr->set_top(new_top); 730 if (_hr_printer.is_active()) { 731 HeapWord* bottom = first_hr->bottom(); 732 HeapWord* end = first_hr->orig_end(); 733 if ((first + 1) == last) { 734 // the series has a single humongous region 735 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); 736 } else { 737 // the series has more than one humongous regions 738 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); 739 } 740 } 741 742 // Now, we will update the top fields of the "continues humongous" 743 // regions. The reason we need to do this is that, otherwise, 744 // these regions would look empty and this will confuse parts of 745 // G1. For example, the code that looks for a consecutive number 746 // of empty regions will consider them empty and try to 747 // re-allocate them. We can extend is_empty() to also include 748 // !continuesHumongous(), but it is easier to just update the top 749 // fields here. The way we set top for all regions (i.e., top == 750 // end for all regions but the last one, top == new_top for the 751 // last one) is actually used when we will free up the humongous 752 // region in free_humongous_region(). 753 hr = NULL; 754 for (uint i = first + 1; i < last; ++i) { 755 hr = region_at(i); 756 if ((i + 1) == last) { 757 // last continues humongous region 758 assert(hr->bottom() < new_top && new_top <= hr->end(), 759 "new_top should fall on this region"); 760 hr->set_top(new_top); 761 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); 762 } else { 763 // not last one 764 assert(new_top > hr->end(), "new_top should be above this region"); 765 hr->set_top(hr->end()); 766 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); 767 } 768 } 769 // If we have continues humongous regions (hr != NULL), then the 770 // end of the last one should match new_end and its top should 771 // match new_top. 772 assert(hr == NULL || 773 (hr->end() == new_end && hr->top() == new_top), "sanity"); 774 775 assert(first_hr->used() == word_size * HeapWordSize, "invariant"); 776 _summary_bytes_used += first_hr->used(); 777 _humongous_set.add(first_hr); 778 779 return new_obj; 780 } 781 782 // If could fit into free regions w/o expansion, try. 783 // Otherwise, if can expand, do so. 784 // Otherwise, if using ex regions might help, try with ex given back. 785 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 786 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 787 788 verify_region_sets_optional(); 789 790 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords); 791 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords); 792 uint x_num = expansion_regions(); 793 uint fs = _hrs.free_suffix(); 794 uint first = humongous_obj_allocate_find_first(num_regions, word_size); 795 if (first == G1_NULL_HRS_INDEX) { 796 // The only thing we can do now is attempt expansion. 797 if (fs + x_num >= num_regions) { 798 // If the number of regions we're trying to allocate for this 799 // object is at most the number of regions in the free suffix, 800 // then the call to humongous_obj_allocate_find_first() above 801 // should have succeeded and we wouldn't be here. 802 // 803 // We should only be trying to expand when the free suffix is 804 // not sufficient for the object _and_ we have some expansion 805 // room available. 806 assert(num_regions > fs, "earlier allocation should have succeeded"); 807 808 ergo_verbose1(ErgoHeapSizing, 809 "attempt heap expansion", 810 ergo_format_reason("humongous allocation request failed") 811 ergo_format_byte("allocation request"), 812 word_size * HeapWordSize); 813 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) { 814 // Even though the heap was expanded, it might not have 815 // reached the desired size. So, we cannot assume that the 816 // allocation will succeed. 817 first = humongous_obj_allocate_find_first(num_regions, word_size); 818 } 819 } 820 } 821 822 HeapWord* result = NULL; 823 if (first != G1_NULL_HRS_INDEX) { 824 result = 825 humongous_obj_allocate_initialize_regions(first, num_regions, word_size); 826 assert(result != NULL, "it should always return a valid result"); 827 828 // A successful humongous object allocation changes the used space 829 // information of the old generation so we need to recalculate the 830 // sizes and update the jstat counters here. 831 g1mm()->update_sizes(); 832 } 833 834 verify_region_sets_optional(); 835 836 return result; 837 } 838 839 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 840 assert_heap_not_locked_and_not_at_safepoint(); 841 assert(!isHumongous(word_size), "we do not allow humongous TLABs"); 842 843 unsigned int dummy_gc_count_before; 844 int dummy_gclocker_retry_count = 0; 845 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); 846 } 847 848 HeapWord* 849 G1CollectedHeap::mem_allocate(size_t word_size, 850 bool* gc_overhead_limit_was_exceeded) { 851 assert_heap_not_locked_and_not_at_safepoint(); 852 853 // Loop until the allocation is satisfied, or unsatisfied after GC. 854 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 855 unsigned int gc_count_before; 856 857 HeapWord* result = NULL; 858 if (!isHumongous(word_size)) { 859 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); 860 } else { 861 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); 862 } 863 if (result != NULL) { 864 return result; 865 } 866 867 // Create the garbage collection operation... 868 VM_G1CollectForAllocation op(gc_count_before, word_size); 869 // ...and get the VM thread to execute it. 870 VMThread::execute(&op); 871 872 if (op.prologue_succeeded() && op.pause_succeeded()) { 873 // If the operation was successful we'll return the result even 874 // if it is NULL. If the allocation attempt failed immediately 875 // after a Full GC, it's unlikely we'll be able to allocate now. 876 HeapWord* result = op.result(); 877 if (result != NULL && !isHumongous(word_size)) { 878 // Allocations that take place on VM operations do not do any 879 // card dirtying and we have to do it here. We only have to do 880 // this for non-humongous allocations, though. 881 dirty_young_block(result, word_size); 882 } 883 return result; 884 } else { 885 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 886 return NULL; 887 } 888 assert(op.result() == NULL, 889 "the result should be NULL if the VM op did not succeed"); 890 } 891 892 // Give a warning if we seem to be looping forever. 893 if ((QueuedAllocationWarningCount > 0) && 894 (try_count % QueuedAllocationWarningCount == 0)) { 895 warning("G1CollectedHeap::mem_allocate retries %d times", try_count); 896 } 897 } 898 899 ShouldNotReachHere(); 900 return NULL; 901 } 902 903 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, 904 unsigned int *gc_count_before_ret, 905 int* gclocker_retry_count_ret) { 906 // Make sure you read the note in attempt_allocation_humongous(). 907 908 assert_heap_not_locked_and_not_at_safepoint(); 909 assert(!isHumongous(word_size), "attempt_allocation_slow() should not " 910 "be called for humongous allocation requests"); 911 912 // We should only get here after the first-level allocation attempt 913 // (attempt_allocation()) failed to allocate. 914 915 // We will loop until a) we manage to successfully perform the 916 // allocation or b) we successfully schedule a collection which 917 // fails to perform the allocation. b) is the only case when we'll 918 // return NULL. 919 HeapWord* result = NULL; 920 for (int try_count = 1; /* we'll return */; try_count += 1) { 921 bool should_try_gc; 922 unsigned int gc_count_before; 923 924 { 925 MutexLockerEx x(Heap_lock); 926 927 result = _mutator_alloc_region.attempt_allocation_locked(word_size, 928 false /* bot_updates */); 929 if (result != NULL) { 930 return result; 931 } 932 933 // If we reach here, attempt_allocation_locked() above failed to 934 // allocate a new region. So the mutator alloc region should be NULL. 935 assert(_mutator_alloc_region.get() == NULL, "only way to get here"); 936 937 if (GC_locker::is_active_and_needs_gc()) { 938 if (g1_policy()->can_expand_young_list()) { 939 // No need for an ergo verbose message here, 940 // can_expand_young_list() does this when it returns true. 941 result = _mutator_alloc_region.attempt_allocation_force(word_size, 942 false /* bot_updates */); 943 if (result != NULL) { 944 return result; 945 } 946 } 947 should_try_gc = false; 948 } else { 949 // The GCLocker may not be active but the GCLocker initiated 950 // GC may not yet have been performed (GCLocker::needs_gc() 951 // returns true). In this case we do not try this GC and 952 // wait until the GCLocker initiated GC is performed, and 953 // then retry the allocation. 954 if (GC_locker::needs_gc()) { 955 should_try_gc = false; 956 } else { 957 // Read the GC count while still holding the Heap_lock. 958 gc_count_before = total_collections(); 959 should_try_gc = true; 960 } 961 } 962 } 963 964 if (should_try_gc) { 965 bool succeeded; 966 result = do_collection_pause(word_size, gc_count_before, &succeeded, 967 GCCause::_g1_inc_collection_pause); 968 if (result != NULL) { 969 assert(succeeded, "only way to get back a non-NULL result"); 970 return result; 971 } 972 973 if (succeeded) { 974 // If we get here we successfully scheduled a collection which 975 // failed to allocate. No point in trying to allocate 976 // further. We'll just return NULL. 977 MutexLockerEx x(Heap_lock); 978 *gc_count_before_ret = total_collections(); 979 return NULL; 980 } 981 } else { 982 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 983 MutexLockerEx x(Heap_lock); 984 *gc_count_before_ret = total_collections(); 985 return NULL; 986 } 987 // The GCLocker is either active or the GCLocker initiated 988 // GC has not yet been performed. Stall until it is and 989 // then retry the allocation. 990 GC_locker::stall_until_clear(); 991 (*gclocker_retry_count_ret) += 1; 992 } 993 994 // We can reach here if we were unsuccessful in scheduling a 995 // collection (because another thread beat us to it) or if we were 996 // stalled due to the GC locker. In either can we should retry the 997 // allocation attempt in case another thread successfully 998 // performed a collection and reclaimed enough space. We do the 999 // first attempt (without holding the Heap_lock) here and the 1000 // follow-on attempt will be at the start of the next loop 1001 // iteration (after taking the Heap_lock). 1002 result = _mutator_alloc_region.attempt_allocation(word_size, 1003 false /* bot_updates */); 1004 if (result != NULL) { 1005 return result; 1006 } 1007 1008 // Give a warning if we seem to be looping forever. 1009 if ((QueuedAllocationWarningCount > 0) && 1010 (try_count % QueuedAllocationWarningCount == 0)) { 1011 warning("G1CollectedHeap::attempt_allocation_slow() " 1012 "retries %d times", try_count); 1013 } 1014 } 1015 1016 ShouldNotReachHere(); 1017 return NULL; 1018 } 1019 1020 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, 1021 unsigned int * gc_count_before_ret, 1022 int* gclocker_retry_count_ret) { 1023 // The structure of this method has a lot of similarities to 1024 // attempt_allocation_slow(). The reason these two were not merged 1025 // into a single one is that such a method would require several "if 1026 // allocation is not humongous do this, otherwise do that" 1027 // conditional paths which would obscure its flow. In fact, an early 1028 // version of this code did use a unified method which was harder to 1029 // follow and, as a result, it had subtle bugs that were hard to 1030 // track down. So keeping these two methods separate allows each to 1031 // be more readable. It will be good to keep these two in sync as 1032 // much as possible. 1033 1034 assert_heap_not_locked_and_not_at_safepoint(); 1035 assert(isHumongous(word_size), "attempt_allocation_humongous() " 1036 "should only be called for humongous allocations"); 1037 1038 // Humongous objects can exhaust the heap quickly, so we should check if we 1039 // need to start a marking cycle at each humongous object allocation. We do 1040 // the check before we do the actual allocation. The reason for doing it 1041 // before the allocation is that we avoid having to keep track of the newly 1042 // allocated memory while we do a GC. 1043 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 1044 word_size)) { 1045 collect(GCCause::_g1_humongous_allocation); 1046 } 1047 1048 // We will loop until a) we manage to successfully perform the 1049 // allocation or b) we successfully schedule a collection which 1050 // fails to perform the allocation. b) is the only case when we'll 1051 // return NULL. 1052 HeapWord* result = NULL; 1053 for (int try_count = 1; /* we'll return */; try_count += 1) { 1054 bool should_try_gc; 1055 unsigned int gc_count_before; 1056 1057 { 1058 MutexLockerEx x(Heap_lock); 1059 1060 // Given that humongous objects are not allocated in young 1061 // regions, we'll first try to do the allocation without doing a 1062 // collection hoping that there's enough space in the heap. 1063 result = humongous_obj_allocate(word_size); 1064 if (result != NULL) { 1065 return result; 1066 } 1067 1068 if (GC_locker::is_active_and_needs_gc()) { 1069 should_try_gc = false; 1070 } else { 1071 // The GCLocker may not be active but the GCLocker initiated 1072 // GC may not yet have been performed (GCLocker::needs_gc() 1073 // returns true). In this case we do not try this GC and 1074 // wait until the GCLocker initiated GC is performed, and 1075 // then retry the allocation. 1076 if (GC_locker::needs_gc()) { 1077 should_try_gc = false; 1078 } else { 1079 // Read the GC count while still holding the Heap_lock. 1080 gc_count_before = total_collections(); 1081 should_try_gc = true; 1082 } 1083 } 1084 } 1085 1086 if (should_try_gc) { 1087 // If we failed to allocate the humongous object, we should try to 1088 // do a collection pause (if we're allowed) in case it reclaims 1089 // enough space for the allocation to succeed after the pause. 1090 1091 bool succeeded; 1092 result = do_collection_pause(word_size, gc_count_before, &succeeded, 1093 GCCause::_g1_humongous_allocation); 1094 if (result != NULL) { 1095 assert(succeeded, "only way to get back a non-NULL result"); 1096 return result; 1097 } 1098 1099 if (succeeded) { 1100 // If we get here we successfully scheduled a collection which 1101 // failed to allocate. No point in trying to allocate 1102 // further. We'll just return NULL. 1103 MutexLockerEx x(Heap_lock); 1104 *gc_count_before_ret = total_collections(); 1105 return NULL; 1106 } 1107 } else { 1108 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { 1109 MutexLockerEx x(Heap_lock); 1110 *gc_count_before_ret = total_collections(); 1111 return NULL; 1112 } 1113 // The GCLocker is either active or the GCLocker initiated 1114 // GC has not yet been performed. Stall until it is and 1115 // then retry the allocation. 1116 GC_locker::stall_until_clear(); 1117 (*gclocker_retry_count_ret) += 1; 1118 } 1119 1120 // We can reach here if we were unsuccessful in scheduling a 1121 // collection (because another thread beat us to it) or if we were 1122 // stalled due to the GC locker. In either can we should retry the 1123 // allocation attempt in case another thread successfully 1124 // performed a collection and reclaimed enough space. Give a 1125 // warning if we seem to be looping forever. 1126 1127 if ((QueuedAllocationWarningCount > 0) && 1128 (try_count % QueuedAllocationWarningCount == 0)) { 1129 warning("G1CollectedHeap::attempt_allocation_humongous() " 1130 "retries %d times", try_count); 1131 } 1132 } 1133 1134 ShouldNotReachHere(); 1135 return NULL; 1136 } 1137 1138 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 1139 bool expect_null_mutator_alloc_region) { 1140 assert_at_safepoint(true /* should_be_vm_thread */); 1141 assert(_mutator_alloc_region.get() == NULL || 1142 !expect_null_mutator_alloc_region, 1143 "the current alloc region was unexpectedly found to be non-NULL"); 1144 1145 if (!isHumongous(word_size)) { 1146 return _mutator_alloc_region.attempt_allocation_locked(word_size, 1147 false /* bot_updates */); 1148 } else { 1149 HeapWord* result = humongous_obj_allocate(word_size); 1150 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 1151 g1_policy()->set_initiate_conc_mark_if_possible(); 1152 } 1153 return result; 1154 } 1155 1156 ShouldNotReachHere(); 1157 } 1158 1159 class PostMCRemSetClearClosure: public HeapRegionClosure { 1160 G1CollectedHeap* _g1h; 1161 ModRefBarrierSet* _mr_bs; 1162 public: 1163 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : 1164 _g1h(g1h), _mr_bs(mr_bs) {} 1165 1166 bool doHeapRegion(HeapRegion* r) { 1167 HeapRegionRemSet* hrrs = r->rem_set(); 1168 1169 if (r->continuesHumongous()) { 1170 // We'll assert that the strong code root list and RSet is empty 1171 assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); 1172 assert(hrrs->occupied() == 0, "RSet should be empty"); 1173 return false; 1174 } 1175 1176 _g1h->reset_gc_time_stamps(r); 1177 hrrs->clear(); 1178 // You might think here that we could clear just the cards 1179 // corresponding to the used region. But no: if we leave a dirty card 1180 // in a region we might allocate into, then it would prevent that card 1181 // from being enqueued, and cause it to be missed. 1182 // Re: the performance cost: we shouldn't be doing full GC anyway! 1183 _mr_bs->clear(MemRegion(r->bottom(), r->end())); 1184 1185 return false; 1186 } 1187 }; 1188 1189 void G1CollectedHeap::clear_rsets_post_compaction() { 1190 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); 1191 heap_region_iterate(&rs_clear); 1192 } 1193 1194 class RebuildRSOutOfRegionClosure: public HeapRegionClosure { 1195 G1CollectedHeap* _g1h; 1196 UpdateRSOopClosure _cl; 1197 int _worker_i; 1198 public: 1199 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) : 1200 _cl(g1->g1_rem_set(), worker_i), 1201 _worker_i(worker_i), 1202 _g1h(g1) 1203 { } 1204 1205 bool doHeapRegion(HeapRegion* r) { 1206 if (!r->continuesHumongous()) { 1207 _cl.set_from(r); 1208 r->oop_iterate(&_cl); 1209 } 1210 return false; 1211 } 1212 }; 1213 1214 class ParRebuildRSTask: public AbstractGangTask { 1215 G1CollectedHeap* _g1; 1216 public: 1217 ParRebuildRSTask(G1CollectedHeap* g1) 1218 : AbstractGangTask("ParRebuildRSTask"), 1219 _g1(g1) 1220 { } 1221 1222 void work(uint worker_id) { 1223 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); 1224 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id, 1225 _g1->workers()->active_workers(), 1226 HeapRegion::RebuildRSClaimValue); 1227 } 1228 }; 1229 1230 class PostCompactionPrinterClosure: public HeapRegionClosure { 1231 private: 1232 G1HRPrinter* _hr_printer; 1233 public: 1234 bool doHeapRegion(HeapRegion* hr) { 1235 assert(!hr->is_young(), "not expecting to find young regions"); 1236 // We only generate output for non-empty regions. 1237 if (!hr->is_empty()) { 1238 if (!hr->isHumongous()) { 1239 _hr_printer->post_compaction(hr, G1HRPrinter::Old); 1240 } else if (hr->startsHumongous()) { 1241 if (hr->region_num() == 1) { 1242 // single humongous region 1243 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); 1244 } else { 1245 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); 1246 } 1247 } else { 1248 assert(hr->continuesHumongous(), "only way to get here"); 1249 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); 1250 } 1251 } 1252 return false; 1253 } 1254 1255 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1256 : _hr_printer(hr_printer) { } 1257 }; 1258 1259 void G1CollectedHeap::print_hrs_post_compaction() { 1260 PostCompactionPrinterClosure cl(hr_printer()); 1261 heap_region_iterate(&cl); 1262 } 1263 1264 bool G1CollectedHeap::do_collection(bool explicit_gc, 1265 bool clear_all_soft_refs, 1266 size_t word_size) { 1267 assert_at_safepoint(true /* should_be_vm_thread */); 1268 1269 if (GC_locker::check_active_before_gc()) { 1270 return false; 1271 } 1272 1273 STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); 1274 gc_timer->register_gc_start(); 1275 1276 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); 1277 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); 1278 1279 SvcGCMarker sgcm(SvcGCMarker::FULL); 1280 ResourceMark rm; 1281 1282 print_heap_before_gc(); 1283 trace_heap_before_gc(gc_tracer); 1284 1285 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 1286 1287 verify_region_sets_optional(); 1288 1289 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1290 collector_policy()->should_clear_all_soft_refs(); 1291 1292 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 1293 1294 { 1295 IsGCActiveMark x; 1296 1297 // Timing 1298 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); 1299 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps); 1300 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 1301 1302 { 1303 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL); 1304 TraceCollectorStats tcs(g1mm()->full_collection_counters()); 1305 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); 1306 1307 double start = os::elapsedTime(); 1308 g1_policy()->record_full_collection_start(); 1309 1310 // Note: When we have a more flexible GC logging framework that 1311 // allows us to add optional attributes to a GC log record we 1312 // could consider timing and reporting how long we wait in the 1313 // following two methods. 1314 wait_while_free_regions_coming(); 1315 // If we start the compaction before the CM threads finish 1316 // scanning the root regions we might trip them over as we'll 1317 // be moving objects / updating references. So let's wait until 1318 // they are done. By telling them to abort, they should complete 1319 // early. 1320 _cm->root_regions()->abort(); 1321 _cm->root_regions()->wait_until_scan_finished(); 1322 append_secondary_free_list_if_not_empty_with_lock(); 1323 1324 gc_prologue(true); 1325 increment_total_collections(true /* full gc */); 1326 increment_old_marking_cycles_started(); 1327 1328 assert(used() == recalculate_used(), "Should be equal"); 1329 1330 verify_before_gc(); 1331 1332 pre_full_gc_dump(gc_timer); 1333 1334 COMPILER2_PRESENT(DerivedPointerTable::clear()); 1335 1336 // Disable discovery and empty the discovered lists 1337 // for the CM ref processor. 1338 ref_processor_cm()->disable_discovery(); 1339 ref_processor_cm()->abandon_partial_discovery(); 1340 ref_processor_cm()->verify_no_references_recorded(); 1341 1342 // Abandon current iterations of concurrent marking and concurrent 1343 // refinement, if any are in progress. We have to do this before 1344 // wait_until_scan_finished() below. 1345 concurrent_mark()->abort(); 1346 1347 // Make sure we'll choose a new allocation region afterwards. 1348 release_mutator_alloc_region(); 1349 abandon_gc_alloc_regions(); 1350 g1_rem_set()->cleanupHRRS(); 1351 1352 // We should call this after we retire any currently active alloc 1353 // regions so that all the ALLOC / RETIRE events are generated 1354 // before the start GC event. 1355 _hr_printer.start_gc(true /* full */, (size_t) total_collections()); 1356 1357 // We may have added regions to the current incremental collection 1358 // set between the last GC or pause and now. We need to clear the 1359 // incremental collection set and then start rebuilding it afresh 1360 // after this full GC. 1361 abandon_collection_set(g1_policy()->inc_cset_head()); 1362 g1_policy()->clear_incremental_cset(); 1363 g1_policy()->stop_incremental_cset_building(); 1364 1365 tear_down_region_sets(false /* free_list_only */); 1366 g1_policy()->set_gcs_are_young(true); 1367 1368 // See the comments in g1CollectedHeap.hpp and 1369 // G1CollectedHeap::ref_processing_init() about 1370 // how reference processing currently works in G1. 1371 1372 // Temporarily make discovery by the STW ref processor single threaded (non-MT). 1373 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); 1374 1375 // Temporarily clear the STW ref processor's _is_alive_non_header field. 1376 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); 1377 1378 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 1379 ref_processor_stw()->setup_policy(do_clear_all_soft_refs); 1380 1381 // Do collection work 1382 { 1383 HandleMark hm; // Discard invalid handles created during gc 1384 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); 1385 } 1386 1387 assert(free_regions() == 0, "we should not have added any free regions"); 1388 rebuild_region_sets(false /* free_list_only */); 1389 1390 // Enqueue any discovered reference objects that have 1391 // not been removed from the discovered lists. 1392 ref_processor_stw()->enqueue_discovered_references(); 1393 1394 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1395 1396 MemoryService::track_memory_usage(); 1397 1398 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 1399 ref_processor_stw()->verify_no_references_recorded(); 1400 1401 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1402 ClassLoaderDataGraph::purge(); 1403 MetaspaceAux::verify_metrics(); 1404 1405 // Note: since we've just done a full GC, concurrent 1406 // marking is no longer active. Therefore we need not 1407 // re-enable reference discovery for the CM ref processor. 1408 // That will be done at the start of the next marking cycle. 1409 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); 1410 ref_processor_cm()->verify_no_references_recorded(); 1411 1412 reset_gc_time_stamp(); 1413 // Since everything potentially moved, we will clear all remembered 1414 // sets, and clear all cards. Later we will rebuild remembered 1415 // sets. We will also reset the GC time stamps of the regions. 1416 clear_rsets_post_compaction(); 1417 check_gc_time_stamps(); 1418 1419 // Resize the heap if necessary. 1420 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); 1421 1422 if (_hr_printer.is_active()) { 1423 // We should do this after we potentially resize the heap so 1424 // that all the COMMIT / UNCOMMIT events are generated before 1425 // the end GC event. 1426 1427 print_hrs_post_compaction(); 1428 _hr_printer.end_gc(true /* full */, (size_t) total_collections()); 1429 } 1430 1431 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 1432 if (hot_card_cache->use_cache()) { 1433 hot_card_cache->reset_card_counts(); 1434 hot_card_cache->reset_hot_cache(); 1435 } 1436 1437 // Rebuild remembered sets of all regions. 1438 if (G1CollectedHeap::use_parallel_gc_threads()) { 1439 uint n_workers = 1440 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 1441 workers()->active_workers(), 1442 Threads::number_of_non_daemon_threads()); 1443 assert(UseDynamicNumberOfGCThreads || 1444 n_workers == workers()->total_workers(), 1445 "If not dynamic should be using all the workers"); 1446 workers()->set_active_workers(n_workers); 1447 // Set parallel threads in the heap (_n_par_threads) only 1448 // before a parallel phase and always reset it to 0 after 1449 // the phase so that the number of parallel threads does 1450 // no get carried forward to a serial phase where there 1451 // may be code that is "possibly_parallel". 1452 set_par_threads(n_workers); 1453 1454 ParRebuildRSTask rebuild_rs_task(this); 1455 assert(check_heap_region_claim_values( 1456 HeapRegion::InitialClaimValue), "sanity check"); 1457 assert(UseDynamicNumberOfGCThreads || 1458 workers()->active_workers() == workers()->total_workers(), 1459 "Unless dynamic should use total workers"); 1460 // Use the most recent number of active workers 1461 assert(workers()->active_workers() > 0, 1462 "Active workers not properly set"); 1463 set_par_threads(workers()->active_workers()); 1464 workers()->run_task(&rebuild_rs_task); 1465 set_par_threads(0); 1466 assert(check_heap_region_claim_values( 1467 HeapRegion::RebuildRSClaimValue), "sanity check"); 1468 reset_heap_region_claim_values(); 1469 } else { 1470 RebuildRSOutOfRegionClosure rebuild_rs(this); 1471 heap_region_iterate(&rebuild_rs); 1472 } 1473 1474 // Rebuild the strong code root lists for each region 1475 rebuild_strong_code_roots(); 1476 1477 if (true) { // FIXME 1478 MetaspaceGC::compute_new_size(); 1479 } 1480 1481 #ifdef TRACESPINNING 1482 ParallelTaskTerminator::print_termination_counts(); 1483 #endif 1484 1485 // Discard all rset updates 1486 JavaThread::dirty_card_queue_set().abandon_logs(); 1487 assert(!G1DeferredRSUpdate 1488 || (G1DeferredRSUpdate && 1489 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any"); 1490 1491 _young_list->reset_sampled_info(); 1492 // At this point there should be no regions in the 1493 // entire heap tagged as young. 1494 assert(check_young_list_empty(true /* check_heap */), 1495 "young list should be empty at this point"); 1496 1497 // Update the number of full collections that have been completed. 1498 increment_old_marking_cycles_completed(false /* concurrent */); 1499 1500 _hrs.verify_optional(); 1501 verify_region_sets_optional(); 1502 1503 verify_after_gc(); 1504 1505 // Start a new incremental collection set for the next pause 1506 assert(g1_policy()->collection_set() == NULL, "must be"); 1507 g1_policy()->start_incremental_cset_building(); 1508 1509 clear_cset_fast_test(); 1510 1511 init_mutator_alloc_region(); 1512 1513 double end = os::elapsedTime(); 1514 g1_policy()->record_full_collection_end(); 1515 1516 if (G1Log::fine()) { 1517 g1_policy()->print_heap_transition(); 1518 } 1519 1520 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 1521 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 1522 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 1523 // before any GC notifications are raised. 1524 g1mm()->update_sizes(); 1525 1526 gc_epilogue(true); 1527 } 1528 1529 if (G1Log::finer()) { 1530 g1_policy()->print_detailed_heap_transition(true /* full */); 1531 } 1532 1533 print_heap_after_gc(); 1534 trace_heap_after_gc(gc_tracer); 1535 1536 post_full_gc_dump(gc_timer); 1537 1538 gc_timer->register_gc_end(); 1539 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 1540 } 1541 1542 return true; 1543 } 1544 1545 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1546 // do_collection() will return whether it succeeded in performing 1547 // the GC. Currently, there is no facility on the 1548 // do_full_collection() API to notify the caller than the collection 1549 // did not succeed (e.g., because it was locked out by the GC 1550 // locker). So, right now, we'll ignore the return value. 1551 bool dummy = do_collection(true, /* explicit_gc */ 1552 clear_all_soft_refs, 1553 0 /* word_size */); 1554 } 1555 1556 // This code is mostly copied from TenuredGeneration. 1557 void 1558 G1CollectedHeap:: 1559 resize_if_necessary_after_full_collection(size_t word_size) { 1560 // Include the current allocation, if any, and bytes that will be 1561 // pre-allocated to support collections, as "used". 1562 const size_t used_after_gc = used(); 1563 const size_t capacity_after_gc = capacity(); 1564 const size_t free_after_gc = capacity_after_gc - used_after_gc; 1565 1566 // This is enforced in arguments.cpp. 1567 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1568 "otherwise the code below doesn't make sense"); 1569 1570 // We don't have floating point command-line arguments 1571 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1572 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1573 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1574 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1575 1576 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1577 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1578 1579 // We have to be careful here as these two calculations can overflow 1580 // 32-bit size_t's. 1581 double used_after_gc_d = (double) used_after_gc; 1582 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1583 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1584 1585 // Let's make sure that they are both under the max heap size, which 1586 // by default will make them fit into a size_t. 1587 double desired_capacity_upper_bound = (double) max_heap_size; 1588 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1589 desired_capacity_upper_bound); 1590 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1591 desired_capacity_upper_bound); 1592 1593 // We can now safely turn them into size_t's. 1594 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1595 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1596 1597 // This assert only makes sense here, before we adjust them 1598 // with respect to the min and max heap size. 1599 assert(minimum_desired_capacity <= maximum_desired_capacity, 1600 err_msg("minimum_desired_capacity = "SIZE_FORMAT", " 1601 "maximum_desired_capacity = "SIZE_FORMAT, 1602 minimum_desired_capacity, maximum_desired_capacity)); 1603 1604 // Should not be greater than the heap max size. No need to adjust 1605 // it with respect to the heap min size as it's a lower bound (i.e., 1606 // we'll try to make the capacity larger than it, not smaller). 1607 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1608 // Should not be less than the heap min size. No need to adjust it 1609 // with respect to the heap max size as it's an upper bound (i.e., 1610 // we'll try to make the capacity smaller than it, not greater). 1611 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1612 1613 if (capacity_after_gc < minimum_desired_capacity) { 1614 // Don't expand unless it's significant 1615 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1616 ergo_verbose4(ErgoHeapSizing, 1617 "attempt heap expansion", 1618 ergo_format_reason("capacity lower than " 1619 "min desired capacity after Full GC") 1620 ergo_format_byte("capacity") 1621 ergo_format_byte("occupancy") 1622 ergo_format_byte_perc("min desired capacity"), 1623 capacity_after_gc, used_after_gc, 1624 minimum_desired_capacity, (double) MinHeapFreeRatio); 1625 expand(expand_bytes); 1626 1627 // No expansion, now see if we want to shrink 1628 } else if (capacity_after_gc > maximum_desired_capacity) { 1629 // Capacity too large, compute shrinking size 1630 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1631 ergo_verbose4(ErgoHeapSizing, 1632 "attempt heap shrinking", 1633 ergo_format_reason("capacity higher than " 1634 "max desired capacity after Full GC") 1635 ergo_format_byte("capacity") 1636 ergo_format_byte("occupancy") 1637 ergo_format_byte_perc("max desired capacity"), 1638 capacity_after_gc, used_after_gc, 1639 maximum_desired_capacity, (double) MaxHeapFreeRatio); 1640 shrink(shrink_bytes); 1641 } 1642 } 1643 1644 1645 HeapWord* 1646 G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1647 bool* succeeded) { 1648 assert_at_safepoint(true /* should_be_vm_thread */); 1649 1650 *succeeded = true; 1651 // Let's attempt the allocation first. 1652 HeapWord* result = 1653 attempt_allocation_at_safepoint(word_size, 1654 false /* expect_null_mutator_alloc_region */); 1655 if (result != NULL) { 1656 assert(*succeeded, "sanity"); 1657 return result; 1658 } 1659 1660 // In a G1 heap, we're supposed to keep allocation from failing by 1661 // incremental pauses. Therefore, at least for now, we'll favor 1662 // expansion over collection. (This might change in the future if we can 1663 // do something smarter than full collection to satisfy a failed alloc.) 1664 result = expand_and_allocate(word_size); 1665 if (result != NULL) { 1666 assert(*succeeded, "sanity"); 1667 return result; 1668 } 1669 1670 // Expansion didn't work, we'll try to do a Full GC. 1671 bool gc_succeeded = do_collection(false, /* explicit_gc */ 1672 false, /* clear_all_soft_refs */ 1673 word_size); 1674 if (!gc_succeeded) { 1675 *succeeded = false; 1676 return NULL; 1677 } 1678 1679 // Retry the allocation 1680 result = attempt_allocation_at_safepoint(word_size, 1681 true /* expect_null_mutator_alloc_region */); 1682 if (result != NULL) { 1683 assert(*succeeded, "sanity"); 1684 return result; 1685 } 1686 1687 // Then, try a Full GC that will collect all soft references. 1688 gc_succeeded = do_collection(false, /* explicit_gc */ 1689 true, /* clear_all_soft_refs */ 1690 word_size); 1691 if (!gc_succeeded) { 1692 *succeeded = false; 1693 return NULL; 1694 } 1695 1696 // Retry the allocation once more 1697 result = attempt_allocation_at_safepoint(word_size, 1698 true /* expect_null_mutator_alloc_region */); 1699 if (result != NULL) { 1700 assert(*succeeded, "sanity"); 1701 return result; 1702 } 1703 1704 assert(!collector_policy()->should_clear_all_soft_refs(), 1705 "Flag should have been handled and cleared prior to this point"); 1706 1707 // What else? We might try synchronous finalization later. If the total 1708 // space available is large enough for the allocation, then a more 1709 // complete compaction phase than we've tried so far might be 1710 // appropriate. 1711 assert(*succeeded, "sanity"); 1712 return NULL; 1713 } 1714 1715 // Attempting to expand the heap sufficiently 1716 // to support an allocation of the given "word_size". If 1717 // successful, perform the allocation and return the address of the 1718 // allocated block, or else "NULL". 1719 1720 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1721 assert_at_safepoint(true /* should_be_vm_thread */); 1722 1723 verify_region_sets_optional(); 1724 1725 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1726 ergo_verbose1(ErgoHeapSizing, 1727 "attempt heap expansion", 1728 ergo_format_reason("allocation request failed") 1729 ergo_format_byte("allocation request"), 1730 word_size * HeapWordSize); 1731 if (expand(expand_bytes)) { 1732 _hrs.verify_optional(); 1733 verify_region_sets_optional(); 1734 return attempt_allocation_at_safepoint(word_size, 1735 false /* expect_null_mutator_alloc_region */); 1736 } 1737 return NULL; 1738 } 1739 1740 void G1CollectedHeap::update_committed_space(HeapWord* old_end, 1741 HeapWord* new_end) { 1742 assert(old_end != new_end, "don't call this otherwise"); 1743 assert((HeapWord*) _g1_storage.high() == new_end, "invariant"); 1744 1745 // Update the committed mem region. 1746 _g1_committed.set_end(new_end); 1747 // Tell the card table about the update. 1748 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed); 1749 // Tell the BOT about the update. 1750 _bot_shared->resize(_g1_committed.word_size()); 1751 // Tell the hot card cache about the update 1752 _cg1r->hot_card_cache()->resize_card_counts(capacity()); 1753 } 1754 1755 bool G1CollectedHeap::expand(size_t expand_bytes) { 1756 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1757 aligned_expand_bytes = align_size_up(aligned_expand_bytes, 1758 HeapRegion::GrainBytes); 1759 ergo_verbose2(ErgoHeapSizing, 1760 "expand the heap", 1761 ergo_format_byte("requested expansion amount") 1762 ergo_format_byte("attempted expansion amount"), 1763 expand_bytes, aligned_expand_bytes); 1764 1765 if (_g1_storage.uncommitted_size() == 0) { 1766 ergo_verbose0(ErgoHeapSizing, 1767 "did not expand the heap", 1768 ergo_format_reason("heap already fully expanded")); 1769 return false; 1770 } 1771 1772 // First commit the memory. 1773 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1774 bool successful = _g1_storage.expand_by(aligned_expand_bytes); 1775 if (successful) { 1776 // Then propagate this update to the necessary data structures. 1777 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1778 update_committed_space(old_end, new_end); 1779 1780 FreeRegionList expansion_list("Local Expansion List"); 1781 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list); 1782 assert(mr.start() == old_end, "post-condition"); 1783 // mr might be a smaller region than what was requested if 1784 // expand_by() was unable to allocate the HeapRegion instances 1785 assert(mr.end() <= new_end, "post-condition"); 1786 1787 size_t actual_expand_bytes = mr.byte_size(); 1788 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1789 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(), 1790 "post-condition"); 1791 if (actual_expand_bytes < aligned_expand_bytes) { 1792 // We could not expand _hrs to the desired size. In this case we 1793 // need to shrink the committed space accordingly. 1794 assert(mr.end() < new_end, "invariant"); 1795 1796 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes; 1797 // First uncommit the memory. 1798 _g1_storage.shrink_by(diff_bytes); 1799 // Then propagate this update to the necessary data structures. 1800 update_committed_space(new_end, mr.end()); 1801 } 1802 _free_list.add_as_tail(&expansion_list); 1803 1804 if (_hr_printer.is_active()) { 1805 HeapWord* curr = mr.start(); 1806 while (curr < mr.end()) { 1807 HeapWord* curr_end = curr + HeapRegion::GrainWords; 1808 _hr_printer.commit(curr, curr_end); 1809 curr = curr_end; 1810 } 1811 assert(curr == mr.end(), "post-condition"); 1812 } 1813 g1_policy()->record_new_heap_size(n_regions()); 1814 } else { 1815 ergo_verbose0(ErgoHeapSizing, 1816 "did not expand the heap", 1817 ergo_format_reason("heap expansion operation failed")); 1818 // The expansion of the virtual storage space was unsuccessful. 1819 // Let's see if it was because we ran out of swap. 1820 if (G1ExitOnExpansionFailure && 1821 _g1_storage.uncommitted_size() >= aligned_expand_bytes) { 1822 // We had head room... 1823 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1824 } 1825 } 1826 return successful; 1827 } 1828 1829 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 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_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1835 1836 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove); 1837 HeapWord* old_end = (HeapWord*) _g1_storage.high(); 1838 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1839 1840 ergo_verbose3(ErgoHeapSizing, 1841 "shrink the heap", 1842 ergo_format_byte("requested shrinking amount") 1843 ergo_format_byte("aligned shrinking amount") 1844 ergo_format_byte("attempted shrinking amount"), 1845 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1846 if (num_regions_removed > 0) { 1847 _g1_storage.shrink_by(shrunk_bytes); 1848 HeapWord* new_end = (HeapWord*) _g1_storage.high(); 1849 1850 if (_hr_printer.is_active()) { 1851 HeapWord* curr = old_end; 1852 while (curr > new_end) { 1853 HeapWord* curr_end = curr; 1854 curr -= HeapRegion::GrainWords; 1855 _hr_printer.uncommit(curr, curr_end); 1856 } 1857 } 1858 1859 _expansion_regions += num_regions_removed; 1860 update_committed_space(old_end, new_end); 1861 HeapRegionRemSet::shrink_heap(n_regions()); 1862 g1_policy()->record_new_heap_size(n_regions()); 1863 } else { 1864 ergo_verbose0(ErgoHeapSizing, 1865 "did not shrink the heap", 1866 ergo_format_reason("heap shrinking operation failed")); 1867 } 1868 } 1869 1870 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1871 verify_region_sets_optional(); 1872 1873 // We should only reach here at the end of a Full GC which means we 1874 // should not not be holding to any GC alloc regions. The method 1875 // below will make sure of that and do any remaining clean up. 1876 abandon_gc_alloc_regions(); 1877 1878 // Instead of tearing down / rebuilding the free lists here, we 1879 // could instead use the remove_all_pending() method on free_list to 1880 // remove only the ones that we need to remove. 1881 tear_down_region_sets(true /* free_list_only */); 1882 shrink_helper(shrink_bytes); 1883 rebuild_region_sets(true /* free_list_only */); 1884 1885 _hrs.verify_optional(); 1886 verify_region_sets_optional(); 1887 } 1888 1889 // Public methods. 1890 1891 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 1892 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 1893 #endif // _MSC_VER 1894 1895 1896 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : 1897 SharedHeap(policy_), 1898 _g1_policy(policy_), 1899 _dirty_card_queue_set(false), 1900 _into_cset_dirty_card_queue_set(false), 1901 _is_alive_closure_cm(this), 1902 _is_alive_closure_stw(this), 1903 _ref_processor_cm(NULL), 1904 _ref_processor_stw(NULL), 1905 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)), 1906 _bot_shared(NULL), 1907 _evac_failure_scan_stack(NULL), 1908 _mark_in_progress(false), 1909 _cg1r(NULL), _summary_bytes_used(0), 1910 _g1mm(NULL), 1911 _refine_cte_cl(NULL), 1912 _full_collection(false), 1913 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()), 1914 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), 1915 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1916 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1917 _free_regions_coming(false), 1918 _young_list(new YoungList(this)), 1919 _gc_time_stamp(0), 1920 _retained_old_gc_alloc_region(NULL), 1921 _survivor_plab_stats(YoungPLABSize, PLABWeight), 1922 _old_plab_stats(OldPLABSize, PLABWeight), 1923 _expand_heap_after_alloc_failure(true), 1924 _surviving_young_words(NULL), 1925 _old_marking_cycles_started(0), 1926 _old_marking_cycles_completed(0), 1927 _concurrent_cycle_started(false), 1928 _in_cset_fast_test(), 1929 _dirty_cards_region_list(NULL), 1930 _worker_cset_start_region(NULL), 1931 _worker_cset_start_region_time_stamp(NULL), 1932 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1933 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), 1934 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1935 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { 1936 1937 _g1h = this; 1938 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) { 1939 vm_exit_during_initialization("Failed necessary allocation."); 1940 } 1941 1942 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; 1943 1944 int n_queues = MAX2((int)ParallelGCThreads, 1); 1945 _task_queues = new RefToScanQueueSet(n_queues); 1946 1947 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); 1948 assert(n_rem_sets > 0, "Invariant."); 1949 1950 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); 1951 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC); 1952 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1953 1954 for (int i = 0; i < n_queues; i++) { 1955 RefToScanQueue* q = new RefToScanQueue(); 1956 q->initialize(); 1957 _task_queues->register_queue(i, q); 1958 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1959 } 1960 clear_cset_start_regions(); 1961 1962 // Initialize the G1EvacuationFailureALot counters and flags. 1963 NOT_PRODUCT(reset_evacuation_should_fail();) 1964 1965 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1966 } 1967 1968 jint G1CollectedHeap::initialize() { 1969 CollectedHeap::pre_initialize(); 1970 os::enable_vtime(); 1971 1972 G1Log::init(); 1973 1974 // Necessary to satisfy locking discipline assertions. 1975 1976 MutexLocker x(Heap_lock); 1977 1978 // We have to initialize the printer before committing the heap, as 1979 // it will be used then. 1980 _hr_printer.set_active(G1PrintHeapRegions); 1981 1982 // While there are no constraints in the GC code that HeapWordSize 1983 // be any particular value, there are multiple other areas in the 1984 // system which believe this to be true (e.g. oop->object_size in some 1985 // cases incorrectly returns the size in wordSize units rather than 1986 // HeapWordSize). 1987 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1988 1989 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1990 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1991 size_t heap_alignment = collector_policy()->heap_alignment(); 1992 1993 // Ensure that the sizes are properly aligned. 1994 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1995 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1996 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1997 1998 _refine_cte_cl = new RefineCardTableEntryClosure(); 1999 2000 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl); 2001 2002 // Reserve the maximum. 2003 2004 // When compressed oops are enabled, the preferred heap base 2005 // is calculated by subtracting the requested size from the 2006 // 32Gb boundary and using the result as the base address for 2007 // heap reservation. If the requested size is not aligned to 2008 // HeapRegion::GrainBytes (i.e. the alignment that is passed 2009 // into the ReservedHeapSpace constructor) then the actual 2010 // base of the reserved heap may end up differing from the 2011 // address that was requested (i.e. the preferred heap base). 2012 // If this happens then we could end up using a non-optimal 2013 // compressed oops mode. 2014 2015 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 2016 heap_alignment); 2017 2018 // It is important to do this in a way such that concurrent readers can't 2019 // temporarily think something is in the heap. (I've actually seen this 2020 // happen in asserts: DLD.) 2021 _reserved.set_word_size(0); 2022 _reserved.set_start((HeapWord*)heap_rs.base()); 2023 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size())); 2024 2025 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes); 2026 2027 // Create the gen rem set (and barrier set) for the entire reserved region. 2028 _rem_set = collector_policy()->create_rem_set(_reserved, 2); 2029 set_barrier_set(rem_set()->bs()); 2030 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) { 2031 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS"); 2032 return JNI_ENOMEM; 2033 } 2034 2035 // Also create a G1 rem set. 2036 _g1_rem_set = new G1RemSet(this, g1_barrier_set()); 2037 2038 // Carve out the G1 part of the heap. 2039 2040 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 2041 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(), 2042 g1_rs.size()/HeapWordSize); 2043 2044 _g1_storage.initialize(g1_rs, 0); 2045 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0); 2046 _hrs.initialize((HeapWord*) _g1_reserved.start(), 2047 (HeapWord*) _g1_reserved.end()); 2048 assert(_hrs.max_length() == _expansion_regions, 2049 err_msg("max length: %u expansion regions: %u", 2050 _hrs.max_length(), _expansion_regions)); 2051 2052 // Do later initialization work for concurrent refinement. 2053 _cg1r->init(); 2054 2055 // 6843694 - ensure that the maximum region index can fit 2056 // in the remembered set structures. 2057 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 2058 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 2059 2060 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 2061 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 2062 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 2063 "too many cards per region"); 2064 2065 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 2066 2067 _bot_shared = new G1BlockOffsetSharedArray(_reserved, 2068 heap_word_size(init_byte_size)); 2069 2070 _g1h = this; 2071 2072 _in_cset_fast_test.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes); 2073 2074 // Create the ConcurrentMark data structure and thread. 2075 // (Must do this late, so that "max_regions" is defined.) 2076 _cm = new ConcurrentMark(this, heap_rs); 2077 if (_cm == NULL || !_cm->completed_initialization()) { 2078 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); 2079 return JNI_ENOMEM; 2080 } 2081 _cmThread = _cm->cmThread(); 2082 2083 // Initialize the from_card cache structure of HeapRegionRemSet. 2084 HeapRegionRemSet::init_heap(max_regions()); 2085 2086 // Now expand into the initial heap size. 2087 if (!expand(init_byte_size)) { 2088 vm_shutdown_during_initialization("Failed to allocate initial heap."); 2089 return JNI_ENOMEM; 2090 } 2091 2092 // Perform any initialization actions delegated to the policy. 2093 g1_policy()->init(); 2094 2095 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 2096 SATB_Q_FL_lock, 2097 G1SATBProcessCompletedThreshold, 2098 Shared_SATB_Q_lock); 2099 2100 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, 2101 DirtyCardQ_CBL_mon, 2102 DirtyCardQ_FL_lock, 2103 concurrent_g1_refine()->yellow_zone(), 2104 concurrent_g1_refine()->red_zone(), 2105 Shared_DirtyCardQ_lock); 2106 2107 if (G1DeferredRSUpdate) { 2108 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code 2109 DirtyCardQ_CBL_mon, 2110 DirtyCardQ_FL_lock, 2111 -1, // never trigger processing 2112 -1, // no limit on length 2113 Shared_DirtyCardQ_lock, 2114 &JavaThread::dirty_card_queue_set()); 2115 } 2116 2117 // Initialize the card queue set used to hold cards containing 2118 // references into the collection set. 2119 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code 2120 DirtyCardQ_CBL_mon, 2121 DirtyCardQ_FL_lock, 2122 -1, // never trigger processing 2123 -1, // no limit on length 2124 Shared_DirtyCardQ_lock, 2125 &JavaThread::dirty_card_queue_set()); 2126 2127 // In case we're keeping closure specialization stats, initialize those 2128 // counts and that mechanism. 2129 SpecializationStats::clear(); 2130 2131 // Here we allocate the dummy full region that is required by the 2132 // G1AllocRegion class. If we don't pass an address in the reserved 2133 // space here, lots of asserts fire. 2134 2135 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */, 2136 _g1_reserved.start()); 2137 // We'll re-use the same region whether the alloc region will 2138 // require BOT updates or not and, if it doesn't, then a non-young 2139 // region will complain that it cannot support allocations without 2140 // BOT updates. So we'll tag the dummy region as young to avoid that. 2141 dummy_region->set_young(); 2142 // Make sure it's full. 2143 dummy_region->set_top(dummy_region->end()); 2144 G1AllocRegion::setup(this, dummy_region); 2145 2146 init_mutator_alloc_region(); 2147 2148 // Do create of the monitoring and management support so that 2149 // values in the heap have been properly initialized. 2150 _g1mm = new G1MonitoringSupport(this); 2151 2152 G1StringDedup::initialize(); 2153 2154 return JNI_OK; 2155 } 2156 2157 void G1CollectedHeap::stop() { 2158 // Abort any ongoing concurrent root region scanning and stop all 2159 // concurrent threads. We do this to make sure these threads do 2160 // not continue to execute and access resources (e.g. gclog_or_tty) 2161 // that are destroyed during shutdown. 2162 _cm->root_regions()->abort(); 2163 _cm->root_regions()->wait_until_scan_finished(); 2164 stop_conc_gc_threads(); 2165 } 2166 2167 size_t G1CollectedHeap::conservative_max_heap_alignment() { 2168 return HeapRegion::max_region_size(); 2169 } 2170 2171 void G1CollectedHeap::ref_processing_init() { 2172 // Reference processing in G1 currently works as follows: 2173 // 2174 // * There are two reference processor instances. One is 2175 // used to record and process discovered references 2176 // during concurrent marking; the other is used to 2177 // record and process references during STW pauses 2178 // (both full and incremental). 2179 // * Both ref processors need to 'span' the entire heap as 2180 // the regions in the collection set may be dotted around. 2181 // 2182 // * For the concurrent marking ref processor: 2183 // * Reference discovery is enabled at initial marking. 2184 // * Reference discovery is disabled and the discovered 2185 // references processed etc during remarking. 2186 // * Reference discovery is MT (see below). 2187 // * Reference discovery requires a barrier (see below). 2188 // * Reference processing may or may not be MT 2189 // (depending on the value of ParallelRefProcEnabled 2190 // and ParallelGCThreads). 2191 // * A full GC disables reference discovery by the CM 2192 // ref processor and abandons any entries on it's 2193 // discovered lists. 2194 // 2195 // * For the STW processor: 2196 // * Non MT discovery is enabled at the start of a full GC. 2197 // * Processing and enqueueing during a full GC is non-MT. 2198 // * During a full GC, references are processed after marking. 2199 // 2200 // * Discovery (may or may not be MT) is enabled at the start 2201 // of an incremental evacuation pause. 2202 // * References are processed near the end of a STW evacuation pause. 2203 // * For both types of GC: 2204 // * Discovery is atomic - i.e. not concurrent. 2205 // * Reference discovery will not need a barrier. 2206 2207 SharedHeap::ref_processing_init(); 2208 MemRegion mr = reserved_region(); 2209 2210 // Concurrent Mark ref processor 2211 _ref_processor_cm = 2212 new ReferenceProcessor(mr, // span 2213 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2214 // mt processing 2215 (int) ParallelGCThreads, 2216 // degree of mt processing 2217 (ParallelGCThreads > 1) || (ConcGCThreads > 1), 2218 // mt discovery 2219 (int) MAX2(ParallelGCThreads, ConcGCThreads), 2220 // degree of mt discovery 2221 false, 2222 // Reference discovery is not atomic 2223 &_is_alive_closure_cm, 2224 // is alive closure 2225 // (for efficiency/performance) 2226 true); 2227 // Setting next fields of discovered 2228 // lists requires a barrier. 2229 2230 // STW ref processor 2231 _ref_processor_stw = 2232 new ReferenceProcessor(mr, // span 2233 ParallelRefProcEnabled && (ParallelGCThreads > 1), 2234 // mt processing 2235 MAX2((int)ParallelGCThreads, 1), 2236 // degree of mt processing 2237 (ParallelGCThreads > 1), 2238 // mt discovery 2239 MAX2((int)ParallelGCThreads, 1), 2240 // degree of mt discovery 2241 true, 2242 // Reference discovery is atomic 2243 &_is_alive_closure_stw, 2244 // is alive closure 2245 // (for efficiency/performance) 2246 false); 2247 // Setting next fields of discovered 2248 // lists does not require a barrier. 2249 } 2250 2251 size_t G1CollectedHeap::capacity() const { 2252 return _g1_committed.byte_size(); 2253 } 2254 2255 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { 2256 assert(!hr->continuesHumongous(), "pre-condition"); 2257 hr->reset_gc_time_stamp(); 2258 if (hr->startsHumongous()) { 2259 uint first_index = hr->hrs_index() + 1; 2260 uint last_index = hr->last_hc_index(); 2261 for (uint i = first_index; i < last_index; i += 1) { 2262 HeapRegion* chr = region_at(i); 2263 assert(chr->continuesHumongous(), "sanity"); 2264 chr->reset_gc_time_stamp(); 2265 } 2266 } 2267 } 2268 2269 #ifndef PRODUCT 2270 class CheckGCTimeStampsHRClosure : public HeapRegionClosure { 2271 private: 2272 unsigned _gc_time_stamp; 2273 bool _failures; 2274 2275 public: 2276 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : 2277 _gc_time_stamp(gc_time_stamp), _failures(false) { } 2278 2279 virtual bool doHeapRegion(HeapRegion* hr) { 2280 unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); 2281 if (_gc_time_stamp != region_gc_time_stamp) { 2282 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " 2283 "expected %d", HR_FORMAT_PARAMS(hr), 2284 region_gc_time_stamp, _gc_time_stamp); 2285 _failures = true; 2286 } 2287 return false; 2288 } 2289 2290 bool failures() { return _failures; } 2291 }; 2292 2293 void G1CollectedHeap::check_gc_time_stamps() { 2294 CheckGCTimeStampsHRClosure cl(_gc_time_stamp); 2295 heap_region_iterate(&cl); 2296 guarantee(!cl.failures(), "all GC time stamps should have been reset"); 2297 } 2298 #endif // PRODUCT 2299 2300 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, 2301 DirtyCardQueue* into_cset_dcq, 2302 bool concurrent, 2303 uint worker_i) { 2304 // Clean cards in the hot card cache 2305 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 2306 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); 2307 2308 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 2309 int n_completed_buffers = 0; 2310 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { 2311 n_completed_buffers++; 2312 } 2313 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers); 2314 dcqs.clear_n_completed_buffers(); 2315 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 2316 } 2317 2318 2319 // Computes the sum of the storage used by the various regions. 2320 2321 size_t G1CollectedHeap::used() const { 2322 assert(Heap_lock->owner() != NULL, 2323 "Should be owned on this thread's behalf."); 2324 size_t result = _summary_bytes_used; 2325 // Read only once in case it is set to NULL concurrently 2326 HeapRegion* hr = _mutator_alloc_region.get(); 2327 if (hr != NULL) 2328 result += hr->used(); 2329 return result; 2330 } 2331 2332 size_t G1CollectedHeap::used_unlocked() const { 2333 size_t result = _summary_bytes_used; 2334 return result; 2335 } 2336 2337 class SumUsedClosure: public HeapRegionClosure { 2338 size_t _used; 2339 public: 2340 SumUsedClosure() : _used(0) {} 2341 bool doHeapRegion(HeapRegion* r) { 2342 if (!r->continuesHumongous()) { 2343 _used += r->used(); 2344 } 2345 return false; 2346 } 2347 size_t result() { return _used; } 2348 }; 2349 2350 size_t G1CollectedHeap::recalculate_used() const { 2351 double recalculate_used_start = os::elapsedTime(); 2352 2353 SumUsedClosure blk; 2354 heap_region_iterate(&blk); 2355 2356 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 2357 return blk.result(); 2358 } 2359 2360 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2361 switch (cause) { 2362 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2363 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2364 case GCCause::_g1_humongous_allocation: return true; 2365 default: return false; 2366 } 2367 } 2368 2369 #ifndef PRODUCT 2370 void G1CollectedHeap::allocate_dummy_regions() { 2371 // Let's fill up most of the region 2372 size_t word_size = HeapRegion::GrainWords - 1024; 2373 // And as a result the region we'll allocate will be humongous. 2374 guarantee(isHumongous(word_size), "sanity"); 2375 2376 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2377 // Let's use the existing mechanism for the allocation 2378 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2379 if (dummy_obj != NULL) { 2380 MemRegion mr(dummy_obj, word_size); 2381 CollectedHeap::fill_with_object(mr); 2382 } else { 2383 // If we can't allocate once, we probably cannot allocate 2384 // again. Let's get out of the loop. 2385 break; 2386 } 2387 } 2388 } 2389 #endif // !PRODUCT 2390 2391 void G1CollectedHeap::increment_old_marking_cycles_started() { 2392 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2393 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2394 err_msg("Wrong marking cycle count (started: %d, completed: %d)", 2395 _old_marking_cycles_started, _old_marking_cycles_completed)); 2396 2397 _old_marking_cycles_started++; 2398 } 2399 2400 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2401 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2402 2403 // We assume that if concurrent == true, then the caller is a 2404 // concurrent thread that was joined the Suspendible Thread 2405 // Set. If there's ever a cheap way to check this, we should add an 2406 // assert here. 2407 2408 // Given that this method is called at the end of a Full GC or of a 2409 // concurrent cycle, and those can be nested (i.e., a Full GC can 2410 // interrupt a concurrent cycle), the number of full collections 2411 // completed should be either one (in the case where there was no 2412 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2413 // behind the number of full collections started. 2414 2415 // This is the case for the inner caller, i.e. a Full GC. 2416 assert(concurrent || 2417 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2418 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2419 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " 2420 "is inconsistent with _old_marking_cycles_completed = %u", 2421 _old_marking_cycles_started, _old_marking_cycles_completed)); 2422 2423 // This is the case for the outer caller, i.e. the concurrent cycle. 2424 assert(!concurrent || 2425 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2426 err_msg("for outer caller (concurrent cycle): " 2427 "_old_marking_cycles_started = %u " 2428 "is inconsistent with _old_marking_cycles_completed = %u", 2429 _old_marking_cycles_started, _old_marking_cycles_completed)); 2430 2431 _old_marking_cycles_completed += 1; 2432 2433 // We need to clear the "in_progress" flag in the CM thread before 2434 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2435 // is set) so that if a waiter requests another System.gc() it doesn't 2436 // incorrectly see that a marking cycle is still in progress. 2437 if (concurrent) { 2438 _cmThread->clear_in_progress(); 2439 } 2440 2441 // This notify_all() will ensure that a thread that called 2442 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2443 // and it's waiting for a full GC to finish will be woken up. It is 2444 // waiting in VM_G1IncCollectionPause::doit_epilogue(). 2445 FullGCCount_lock->notify_all(); 2446 } 2447 2448 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { 2449 _concurrent_cycle_started = true; 2450 _gc_timer_cm->register_gc_start(start_time); 2451 2452 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); 2453 trace_heap_before_gc(_gc_tracer_cm); 2454 } 2455 2456 void G1CollectedHeap::register_concurrent_cycle_end() { 2457 if (_concurrent_cycle_started) { 2458 if (_cm->has_aborted()) { 2459 _gc_tracer_cm->report_concurrent_mode_failure(); 2460 } 2461 2462 _gc_timer_cm->register_gc_end(); 2463 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); 2464 2465 _concurrent_cycle_started = false; 2466 } 2467 } 2468 2469 void G1CollectedHeap::trace_heap_after_concurrent_cycle() { 2470 if (_concurrent_cycle_started) { 2471 trace_heap_after_gc(_gc_tracer_cm); 2472 } 2473 } 2474 2475 G1YCType G1CollectedHeap::yc_type() { 2476 bool is_young = g1_policy()->gcs_are_young(); 2477 bool is_initial_mark = g1_policy()->during_initial_mark_pause(); 2478 bool is_during_mark = mark_in_progress(); 2479 2480 if (is_initial_mark) { 2481 return InitialMark; 2482 } else if (is_during_mark) { 2483 return DuringMark; 2484 } else if (is_young) { 2485 return Normal; 2486 } else { 2487 return Mixed; 2488 } 2489 } 2490 2491 void G1CollectedHeap::collect(GCCause::Cause cause) { 2492 assert_heap_not_locked(); 2493 2494 unsigned int gc_count_before; 2495 unsigned int old_marking_count_before; 2496 bool retry_gc; 2497 2498 do { 2499 retry_gc = false; 2500 2501 { 2502 MutexLocker ml(Heap_lock); 2503 2504 // Read the GC count while holding the Heap_lock 2505 gc_count_before = total_collections(); 2506 old_marking_count_before = _old_marking_cycles_started; 2507 } 2508 2509 if (should_do_concurrent_full_gc(cause)) { 2510 // Schedule an initial-mark evacuation pause that will start a 2511 // concurrent cycle. We're setting word_size to 0 which means that 2512 // we are not requesting a post-GC allocation. 2513 VM_G1IncCollectionPause op(gc_count_before, 2514 0, /* word_size */ 2515 true, /* should_initiate_conc_mark */ 2516 g1_policy()->max_pause_time_ms(), 2517 cause); 2518 2519 VMThread::execute(&op); 2520 if (!op.pause_succeeded()) { 2521 if (old_marking_count_before == _old_marking_cycles_started) { 2522 retry_gc = op.should_retry_gc(); 2523 } else { 2524 // A Full GC happened while we were trying to schedule the 2525 // initial-mark GC. No point in starting a new cycle given 2526 // that the whole heap was collected anyway. 2527 } 2528 2529 if (retry_gc) { 2530 if (GC_locker::is_active_and_needs_gc()) { 2531 GC_locker::stall_until_clear(); 2532 } 2533 } 2534 } 2535 } else { 2536 if (cause == GCCause::_gc_locker 2537 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2538 2539 // Schedule a standard evacuation pause. We're setting word_size 2540 // to 0 which means that we are not requesting a post-GC allocation. 2541 VM_G1IncCollectionPause op(gc_count_before, 2542 0, /* word_size */ 2543 false, /* should_initiate_conc_mark */ 2544 g1_policy()->max_pause_time_ms(), 2545 cause); 2546 VMThread::execute(&op); 2547 } else { 2548 // Schedule a Full GC. 2549 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause); 2550 VMThread::execute(&op); 2551 } 2552 } 2553 } while (retry_gc); 2554 } 2555 2556 bool G1CollectedHeap::is_in(const void* p) const { 2557 if (_g1_committed.contains(p)) { 2558 // Given that we know that p is in the committed space, 2559 // heap_region_containing_raw() should successfully 2560 // return the containing region. 2561 HeapRegion* hr = heap_region_containing_raw(p); 2562 return hr->is_in(p); 2563 } else { 2564 return false; 2565 } 2566 } 2567 2568 // Iteration functions. 2569 2570 // Iterates an OopClosure over all ref-containing fields of objects 2571 // within a HeapRegion. 2572 2573 class IterateOopClosureRegionClosure: public HeapRegionClosure { 2574 MemRegion _mr; 2575 ExtendedOopClosure* _cl; 2576 public: 2577 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl) 2578 : _mr(mr), _cl(cl) {} 2579 bool doHeapRegion(HeapRegion* r) { 2580 if (!r->continuesHumongous()) { 2581 r->oop_iterate(_cl); 2582 } 2583 return false; 2584 } 2585 }; 2586 2587 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 2588 IterateOopClosureRegionClosure blk(_g1_committed, cl); 2589 heap_region_iterate(&blk); 2590 } 2591 2592 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) { 2593 IterateOopClosureRegionClosure blk(mr, cl); 2594 heap_region_iterate(&blk); 2595 } 2596 2597 // Iterates an ObjectClosure over all objects within a HeapRegion. 2598 2599 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2600 ObjectClosure* _cl; 2601 public: 2602 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2603 bool doHeapRegion(HeapRegion* r) { 2604 if (! r->continuesHumongous()) { 2605 r->object_iterate(_cl); 2606 } 2607 return false; 2608 } 2609 }; 2610 2611 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2612 IterateObjectClosureRegionClosure blk(cl); 2613 heap_region_iterate(&blk); 2614 } 2615 2616 // Calls a SpaceClosure on a HeapRegion. 2617 2618 class SpaceClosureRegionClosure: public HeapRegionClosure { 2619 SpaceClosure* _cl; 2620 public: 2621 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} 2622 bool doHeapRegion(HeapRegion* r) { 2623 _cl->do_space(r); 2624 return false; 2625 } 2626 }; 2627 2628 void G1CollectedHeap::space_iterate(SpaceClosure* cl) { 2629 SpaceClosureRegionClosure blk(cl); 2630 heap_region_iterate(&blk); 2631 } 2632 2633 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2634 _hrs.iterate(cl); 2635 } 2636 2637 void 2638 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl, 2639 uint worker_id, 2640 uint no_of_par_workers, 2641 jint claim_value) { 2642 const uint regions = n_regions(); 2643 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 2644 no_of_par_workers : 2645 1); 2646 assert(UseDynamicNumberOfGCThreads || 2647 no_of_par_workers == workers()->total_workers(), 2648 "Non dynamic should use fixed number of workers"); 2649 // try to spread out the starting points of the workers 2650 const HeapRegion* start_hr = 2651 start_region_for_worker(worker_id, no_of_par_workers); 2652 const uint start_index = start_hr->hrs_index(); 2653 2654 // each worker will actually look at all regions 2655 for (uint count = 0; count < regions; ++count) { 2656 const uint index = (start_index + count) % regions; 2657 assert(0 <= index && index < regions, "sanity"); 2658 HeapRegion* r = region_at(index); 2659 // we'll ignore "continues humongous" regions (we'll process them 2660 // when we come across their corresponding "start humongous" 2661 // region) and regions already claimed 2662 if (r->claim_value() == claim_value || r->continuesHumongous()) { 2663 continue; 2664 } 2665 // OK, try to claim it 2666 if (r->claimHeapRegion(claim_value)) { 2667 // success! 2668 assert(!r->continuesHumongous(), "sanity"); 2669 if (r->startsHumongous()) { 2670 // If the region is "starts humongous" we'll iterate over its 2671 // "continues humongous" first; in fact we'll do them 2672 // first. The order is important. In on case, calling the 2673 // closure on the "starts humongous" region might de-allocate 2674 // and clear all its "continues humongous" regions and, as a 2675 // result, we might end up processing them twice. So, we'll do 2676 // them first (notice: most closures will ignore them anyway) and 2677 // then we'll do the "starts humongous" region. 2678 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) { 2679 HeapRegion* chr = region_at(ch_index); 2680 2681 // if the region has already been claimed or it's not 2682 // "continues humongous" we're done 2683 if (chr->claim_value() == claim_value || 2684 !chr->continuesHumongous()) { 2685 break; 2686 } 2687 2688 // No one should have claimed it directly. We can given 2689 // that we claimed its "starts humongous" region. 2690 assert(chr->claim_value() != claim_value, "sanity"); 2691 assert(chr->humongous_start_region() == r, "sanity"); 2692 2693 if (chr->claimHeapRegion(claim_value)) { 2694 // we should always be able to claim it; no one else should 2695 // be trying to claim this region 2696 2697 bool res2 = cl->doHeapRegion(chr); 2698 assert(!res2, "Should not abort"); 2699 2700 // Right now, this holds (i.e., no closure that actually 2701 // does something with "continues humongous" regions 2702 // clears them). We might have to weaken it in the future, 2703 // but let's leave these two asserts here for extra safety. 2704 assert(chr->continuesHumongous(), "should still be the case"); 2705 assert(chr->humongous_start_region() == r, "sanity"); 2706 } else { 2707 guarantee(false, "we should not reach here"); 2708 } 2709 } 2710 } 2711 2712 assert(!r->continuesHumongous(), "sanity"); 2713 bool res = cl->doHeapRegion(r); 2714 assert(!res, "Should not abort"); 2715 } 2716 } 2717 } 2718 2719 class ResetClaimValuesClosure: public HeapRegionClosure { 2720 public: 2721 bool doHeapRegion(HeapRegion* r) { 2722 r->set_claim_value(HeapRegion::InitialClaimValue); 2723 return false; 2724 } 2725 }; 2726 2727 void G1CollectedHeap::reset_heap_region_claim_values() { 2728 ResetClaimValuesClosure blk; 2729 heap_region_iterate(&blk); 2730 } 2731 2732 void G1CollectedHeap::reset_cset_heap_region_claim_values() { 2733 ResetClaimValuesClosure blk; 2734 collection_set_iterate(&blk); 2735 } 2736 2737 #ifdef ASSERT 2738 // This checks whether all regions in the heap have the correct claim 2739 // value. I also piggy-backed on this a check to ensure that the 2740 // humongous_start_region() information on "continues humongous" 2741 // regions is correct. 2742 2743 class CheckClaimValuesClosure : public HeapRegionClosure { 2744 private: 2745 jint _claim_value; 2746 uint _failures; 2747 HeapRegion* _sh_region; 2748 2749 public: 2750 CheckClaimValuesClosure(jint claim_value) : 2751 _claim_value(claim_value), _failures(0), _sh_region(NULL) { } 2752 bool doHeapRegion(HeapRegion* r) { 2753 if (r->claim_value() != _claim_value) { 2754 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2755 "claim value = %d, should be %d", 2756 HR_FORMAT_PARAMS(r), 2757 r->claim_value(), _claim_value); 2758 ++_failures; 2759 } 2760 if (!r->isHumongous()) { 2761 _sh_region = NULL; 2762 } else if (r->startsHumongous()) { 2763 _sh_region = r; 2764 } else if (r->continuesHumongous()) { 2765 if (r->humongous_start_region() != _sh_region) { 2766 gclog_or_tty->print_cr("Region " HR_FORMAT ", " 2767 "HS = "PTR_FORMAT", should be "PTR_FORMAT, 2768 HR_FORMAT_PARAMS(r), 2769 r->humongous_start_region(), 2770 _sh_region); 2771 ++_failures; 2772 } 2773 } 2774 return false; 2775 } 2776 uint failures() { return _failures; } 2777 }; 2778 2779 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) { 2780 CheckClaimValuesClosure cl(claim_value); 2781 heap_region_iterate(&cl); 2782 return cl.failures() == 0; 2783 } 2784 2785 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure { 2786 private: 2787 jint _claim_value; 2788 uint _failures; 2789 2790 public: 2791 CheckClaimValuesInCSetHRClosure(jint claim_value) : 2792 _claim_value(claim_value), _failures(0) { } 2793 2794 uint failures() { return _failures; } 2795 2796 bool doHeapRegion(HeapRegion* hr) { 2797 assert(hr->in_collection_set(), "how?"); 2798 assert(!hr->isHumongous(), "H-region in CSet"); 2799 if (hr->claim_value() != _claim_value) { 2800 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", " 2801 "claim value = %d, should be %d", 2802 HR_FORMAT_PARAMS(hr), 2803 hr->claim_value(), _claim_value); 2804 _failures += 1; 2805 } 2806 return false; 2807 } 2808 }; 2809 2810 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) { 2811 CheckClaimValuesInCSetHRClosure cl(claim_value); 2812 collection_set_iterate(&cl); 2813 return cl.failures() == 0; 2814 } 2815 #endif // ASSERT 2816 2817 // Clear the cached CSet starting regions and (more importantly) 2818 // the time stamps. Called when we reset the GC time stamp. 2819 void G1CollectedHeap::clear_cset_start_regions() { 2820 assert(_worker_cset_start_region != NULL, "sanity"); 2821 assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); 2822 2823 int n_queues = MAX2((int)ParallelGCThreads, 1); 2824 for (int i = 0; i < n_queues; i++) { 2825 _worker_cset_start_region[i] = NULL; 2826 _worker_cset_start_region_time_stamp[i] = 0; 2827 } 2828 } 2829 2830 // Given the id of a worker, obtain or calculate a suitable 2831 // starting region for iterating over the current collection set. 2832 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { 2833 assert(get_gc_time_stamp() > 0, "should have been updated by now"); 2834 2835 HeapRegion* result = NULL; 2836 unsigned gc_time_stamp = get_gc_time_stamp(); 2837 2838 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { 2839 // Cached starting region for current worker was set 2840 // during the current pause - so it's valid. 2841 // Note: the cached starting heap region may be NULL 2842 // (when the collection set is empty). 2843 result = _worker_cset_start_region[worker_i]; 2844 assert(result == NULL || result->in_collection_set(), "sanity"); 2845 return result; 2846 } 2847 2848 // The cached entry was not valid so let's calculate 2849 // a suitable starting heap region for this worker. 2850 2851 // We want the parallel threads to start their collection 2852 // set iteration at different collection set regions to 2853 // avoid contention. 2854 // If we have: 2855 // n collection set regions 2856 // p threads 2857 // Then thread t will start at region floor ((t * n) / p) 2858 2859 result = g1_policy()->collection_set(); 2860 if (G1CollectedHeap::use_parallel_gc_threads()) { 2861 uint cs_size = g1_policy()->cset_region_length(); 2862 uint active_workers = workers()->active_workers(); 2863 assert(UseDynamicNumberOfGCThreads || 2864 active_workers == workers()->total_workers(), 2865 "Unless dynamic should use total workers"); 2866 2867 uint end_ind = (cs_size * worker_i) / active_workers; 2868 uint start_ind = 0; 2869 2870 if (worker_i > 0 && 2871 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { 2872 // Previous workers starting region is valid 2873 // so let's iterate from there 2874 start_ind = (cs_size * (worker_i - 1)) / active_workers; 2875 result = _worker_cset_start_region[worker_i - 1]; 2876 } 2877 2878 for (uint i = start_ind; i < end_ind; i++) { 2879 result = result->next_in_collection_set(); 2880 } 2881 } 2882 2883 // Note: the calculated starting heap region may be NULL 2884 // (when the collection set is empty). 2885 assert(result == NULL || result->in_collection_set(), "sanity"); 2886 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, 2887 "should be updated only once per pause"); 2888 _worker_cset_start_region[worker_i] = result; 2889 OrderAccess::storestore(); 2890 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; 2891 return result; 2892 } 2893 2894 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i, 2895 uint no_of_par_workers) { 2896 uint worker_num = 2897 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U; 2898 assert(UseDynamicNumberOfGCThreads || 2899 no_of_par_workers == workers()->total_workers(), 2900 "Non dynamic should use fixed number of workers"); 2901 const uint start_index = n_regions() * worker_i / worker_num; 2902 return region_at(start_index); 2903 } 2904 2905 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2906 HeapRegion* r = g1_policy()->collection_set(); 2907 while (r != NULL) { 2908 HeapRegion* next = r->next_in_collection_set(); 2909 if (cl->doHeapRegion(r)) { 2910 cl->incomplete(); 2911 return; 2912 } 2913 r = next; 2914 } 2915 } 2916 2917 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, 2918 HeapRegionClosure *cl) { 2919 if (r == NULL) { 2920 // The CSet is empty so there's nothing to do. 2921 return; 2922 } 2923 2924 assert(r->in_collection_set(), 2925 "Start region must be a member of the collection set."); 2926 HeapRegion* cur = r; 2927 while (cur != NULL) { 2928 HeapRegion* next = cur->next_in_collection_set(); 2929 if (cl->doHeapRegion(cur) && false) { 2930 cl->incomplete(); 2931 return; 2932 } 2933 cur = next; 2934 } 2935 cur = g1_policy()->collection_set(); 2936 while (cur != r) { 2937 HeapRegion* next = cur->next_in_collection_set(); 2938 if (cl->doHeapRegion(cur) && false) { 2939 cl->incomplete(); 2940 return; 2941 } 2942 cur = next; 2943 } 2944 } 2945 2946 CompactibleSpace* G1CollectedHeap::first_compactible_space() { 2947 return n_regions() > 0 ? region_at(0) : NULL; 2948 } 2949 2950 2951 Space* G1CollectedHeap::space_containing(const void* addr) const { 2952 Space* res = heap_region_containing(addr); 2953 return res; 2954 } 2955 2956 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2957 Space* sp = space_containing(addr); 2958 if (sp != NULL) { 2959 return sp->block_start(addr); 2960 } 2961 return NULL; 2962 } 2963 2964 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2965 Space* sp = space_containing(addr); 2966 assert(sp != NULL, "block_size of address outside of heap"); 2967 return sp->block_size(addr); 2968 } 2969 2970 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2971 Space* sp = space_containing(addr); 2972 return sp->block_is_obj(addr); 2973 } 2974 2975 bool G1CollectedHeap::supports_tlab_allocation() const { 2976 return true; 2977 } 2978 2979 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2980 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; 2981 } 2982 2983 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2984 return young_list()->eden_used_bytes(); 2985 } 2986 2987 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2988 // must be smaller than the humongous object limit. 2989 size_t G1CollectedHeap::max_tlab_size() const { 2990 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); 2991 } 2992 2993 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2994 // Return the remaining space in the cur alloc region, but not less than 2995 // the min TLAB size. 2996 2997 // Also, this value can be at most the humongous object threshold, 2998 // since we can't allow tlabs to grow big enough to accommodate 2999 // humongous objects. 3000 3001 HeapRegion* hr = _mutator_alloc_region.get(); 3002 size_t max_tlab = max_tlab_size() * wordSize; 3003 if (hr == NULL) { 3004 return max_tlab; 3005 } else { 3006 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); 3007 } 3008 } 3009 3010 size_t G1CollectedHeap::max_capacity() const { 3011 return _g1_reserved.byte_size(); 3012 } 3013 3014 jlong G1CollectedHeap::millis_since_last_gc() { 3015 // assert(false, "NYI"); 3016 return 0; 3017 } 3018 3019 void G1CollectedHeap::prepare_for_verify() { 3020 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { 3021 ensure_parsability(false); 3022 } 3023 g1_rem_set()->prepare_for_verify(); 3024 } 3025 3026 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, 3027 VerifyOption vo) { 3028 switch (vo) { 3029 case VerifyOption_G1UsePrevMarking: 3030 return hr->obj_allocated_since_prev_marking(obj); 3031 case VerifyOption_G1UseNextMarking: 3032 return hr->obj_allocated_since_next_marking(obj); 3033 case VerifyOption_G1UseMarkWord: 3034 return false; 3035 default: 3036 ShouldNotReachHere(); 3037 } 3038 return false; // keep some compilers happy 3039 } 3040 3041 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { 3042 switch (vo) { 3043 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); 3044 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); 3045 case VerifyOption_G1UseMarkWord: return NULL; 3046 default: ShouldNotReachHere(); 3047 } 3048 return NULL; // keep some compilers happy 3049 } 3050 3051 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { 3052 switch (vo) { 3053 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); 3054 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); 3055 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); 3056 default: ShouldNotReachHere(); 3057 } 3058 return false; // keep some compilers happy 3059 } 3060 3061 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { 3062 switch (vo) { 3063 case VerifyOption_G1UsePrevMarking: return "PTAMS"; 3064 case VerifyOption_G1UseNextMarking: return "NTAMS"; 3065 case VerifyOption_G1UseMarkWord: return "NONE"; 3066 default: ShouldNotReachHere(); 3067 } 3068 return NULL; // keep some compilers happy 3069 } 3070 3071 class VerifyRootsClosure: public OopClosure { 3072 private: 3073 G1CollectedHeap* _g1h; 3074 VerifyOption _vo; 3075 bool _failures; 3076 public: 3077 // _vo == UsePrevMarking -> use "prev" marking information, 3078 // _vo == UseNextMarking -> use "next" marking information, 3079 // _vo == UseMarkWord -> use mark word from object header. 3080 VerifyRootsClosure(VerifyOption vo) : 3081 _g1h(G1CollectedHeap::heap()), 3082 _vo(vo), 3083 _failures(false) { } 3084 3085 bool failures() { return _failures; } 3086 3087 template <class T> void do_oop_nv(T* p) { 3088 T heap_oop = oopDesc::load_heap_oop(p); 3089 if (!oopDesc::is_null(heap_oop)) { 3090 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3091 if (_g1h->is_obj_dead_cond(obj, _vo)) { 3092 gclog_or_tty->print_cr("Root location "PTR_FORMAT" " 3093 "points to dead obj "PTR_FORMAT, p, (void*) obj); 3094 if (_vo == VerifyOption_G1UseMarkWord) { 3095 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark())); 3096 } 3097 obj->print_on(gclog_or_tty); 3098 _failures = true; 3099 } 3100 } 3101 } 3102 3103 void do_oop(oop* p) { do_oop_nv(p); } 3104 void do_oop(narrowOop* p) { do_oop_nv(p); } 3105 }; 3106 3107 class G1VerifyCodeRootOopClosure: public OopClosure { 3108 G1CollectedHeap* _g1h; 3109 OopClosure* _root_cl; 3110 nmethod* _nm; 3111 VerifyOption _vo; 3112 bool _failures; 3113 3114 template <class T> void do_oop_work(T* p) { 3115 // First verify that this root is live 3116 _root_cl->do_oop(p); 3117 3118 if (!G1VerifyHeapRegionCodeRoots) { 3119 // We're not verifying the code roots attached to heap region. 3120 return; 3121 } 3122 3123 // Don't check the code roots during marking verification in a full GC 3124 if (_vo == VerifyOption_G1UseMarkWord) { 3125 return; 3126 } 3127 3128 // Now verify that the current nmethod (which contains p) is 3129 // in the code root list of the heap region containing the 3130 // object referenced by p. 3131 3132 T heap_oop = oopDesc::load_heap_oop(p); 3133 if (!oopDesc::is_null(heap_oop)) { 3134 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 3135 3136 // Now fetch the region containing the object 3137 HeapRegion* hr = _g1h->heap_region_containing(obj); 3138 HeapRegionRemSet* hrrs = hr->rem_set(); 3139 // Verify that the strong code root list for this region 3140 // contains the nmethod 3141 if (!hrrs->strong_code_roots_list_contains(_nm)) { 3142 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " 3143 "from nmethod "PTR_FORMAT" not in strong " 3144 "code roots for region ["PTR_FORMAT","PTR_FORMAT")", 3145 p, _nm, hr->bottom(), hr->end()); 3146 _failures = true; 3147 } 3148 } 3149 } 3150 3151 public: 3152 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): 3153 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} 3154 3155 void do_oop(oop* p) { do_oop_work(p); } 3156 void do_oop(narrowOop* p) { do_oop_work(p); } 3157 3158 void set_nmethod(nmethod* nm) { _nm = nm; } 3159 bool failures() { return _failures; } 3160 }; 3161 3162 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { 3163 G1VerifyCodeRootOopClosure* _oop_cl; 3164 3165 public: 3166 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): 3167 _oop_cl(oop_cl) {} 3168 3169 void do_code_blob(CodeBlob* cb) { 3170 nmethod* nm = cb->as_nmethod_or_null(); 3171 if (nm != NULL) { 3172 _oop_cl->set_nmethod(nm); 3173 nm->oops_do(_oop_cl); 3174 } 3175 } 3176 }; 3177 3178 class YoungRefCounterClosure : public OopClosure { 3179 G1CollectedHeap* _g1h; 3180 int _count; 3181 public: 3182 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} 3183 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } 3184 void do_oop(narrowOop* p) { ShouldNotReachHere(); } 3185 3186 int count() { return _count; } 3187 void reset_count() { _count = 0; }; 3188 }; 3189 3190 class VerifyKlassClosure: public KlassClosure { 3191 YoungRefCounterClosure _young_ref_counter_closure; 3192 OopClosure *_oop_closure; 3193 public: 3194 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} 3195 void do_klass(Klass* k) { 3196 k->oops_do(_oop_closure); 3197 3198 _young_ref_counter_closure.reset_count(); 3199 k->oops_do(&_young_ref_counter_closure); 3200 if (_young_ref_counter_closure.count() > 0) { 3201 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k)); 3202 } 3203 } 3204 }; 3205 3206 class VerifyLivenessOopClosure: public OopClosure { 3207 G1CollectedHeap* _g1h; 3208 VerifyOption _vo; 3209 public: 3210 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): 3211 _g1h(g1h), _vo(vo) 3212 { } 3213 void do_oop(narrowOop *p) { do_oop_work(p); } 3214 void do_oop( oop *p) { do_oop_work(p); } 3215 3216 template <class T> void do_oop_work(T *p) { 3217 oop obj = oopDesc::load_decode_heap_oop(p); 3218 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), 3219 "Dead object referenced by a not dead object"); 3220 } 3221 }; 3222 3223 class VerifyObjsInRegionClosure: public ObjectClosure { 3224 private: 3225 G1CollectedHeap* _g1h; 3226 size_t _live_bytes; 3227 HeapRegion *_hr; 3228 VerifyOption _vo; 3229 public: 3230 // _vo == UsePrevMarking -> use "prev" marking information, 3231 // _vo == UseNextMarking -> use "next" marking information, 3232 // _vo == UseMarkWord -> use mark word from object header. 3233 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) 3234 : _live_bytes(0), _hr(hr), _vo(vo) { 3235 _g1h = G1CollectedHeap::heap(); 3236 } 3237 void do_object(oop o) { 3238 VerifyLivenessOopClosure isLive(_g1h, _vo); 3239 assert(o != NULL, "Huh?"); 3240 if (!_g1h->is_obj_dead_cond(o, _vo)) { 3241 // If the object is alive according to the mark word, 3242 // then verify that the marking information agrees. 3243 // Note we can't verify the contra-positive of the 3244 // above: if the object is dead (according to the mark 3245 // word), it may not be marked, or may have been marked 3246 // but has since became dead, or may have been allocated 3247 // since the last marking. 3248 if (_vo == VerifyOption_G1UseMarkWord) { 3249 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); 3250 } 3251 3252 o->oop_iterate_no_header(&isLive); 3253 if (!_hr->obj_allocated_since_prev_marking(o)) { 3254 size_t obj_size = o->size(); // Make sure we don't overflow 3255 _live_bytes += (obj_size * HeapWordSize); 3256 } 3257 } 3258 } 3259 size_t live_bytes() { return _live_bytes; } 3260 }; 3261 3262 class PrintObjsInRegionClosure : public ObjectClosure { 3263 HeapRegion *_hr; 3264 G1CollectedHeap *_g1; 3265 public: 3266 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { 3267 _g1 = G1CollectedHeap::heap(); 3268 }; 3269 3270 void do_object(oop o) { 3271 if (o != NULL) { 3272 HeapWord *start = (HeapWord *) o; 3273 size_t word_sz = o->size(); 3274 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT 3275 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", 3276 (void*) o, word_sz, 3277 _g1->isMarkedPrev(o), 3278 _g1->isMarkedNext(o), 3279 _hr->obj_allocated_since_prev_marking(o)); 3280 HeapWord *end = start + word_sz; 3281 HeapWord *cur; 3282 int *val; 3283 for (cur = start; cur < end; cur++) { 3284 val = (int *) cur; 3285 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val); 3286 } 3287 } 3288 } 3289 }; 3290 3291 class VerifyRegionClosure: public HeapRegionClosure { 3292 private: 3293 bool _par; 3294 VerifyOption _vo; 3295 bool _failures; 3296 public: 3297 // _vo == UsePrevMarking -> use "prev" marking information, 3298 // _vo == UseNextMarking -> use "next" marking information, 3299 // _vo == UseMarkWord -> use mark word from object header. 3300 VerifyRegionClosure(bool par, VerifyOption vo) 3301 : _par(par), 3302 _vo(vo), 3303 _failures(false) {} 3304 3305 bool failures() { 3306 return _failures; 3307 } 3308 3309 bool doHeapRegion(HeapRegion* r) { 3310 if (!r->continuesHumongous()) { 3311 bool failures = false; 3312 r->verify(_vo, &failures); 3313 if (failures) { 3314 _failures = true; 3315 } else { 3316 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); 3317 r->object_iterate(¬_dead_yet_cl); 3318 if (_vo != VerifyOption_G1UseNextMarking) { 3319 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { 3320 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " 3321 "max_live_bytes "SIZE_FORMAT" " 3322 "< calculated "SIZE_FORMAT, 3323 r->bottom(), r->end(), 3324 r->max_live_bytes(), 3325 not_dead_yet_cl.live_bytes()); 3326 _failures = true; 3327 } 3328 } else { 3329 // When vo == UseNextMarking we cannot currently do a sanity 3330 // check on the live bytes as the calculation has not been 3331 // finalized yet. 3332 } 3333 } 3334 } 3335 return false; // stop the region iteration if we hit a failure 3336 } 3337 }; 3338 3339 // This is the task used for parallel verification of the heap regions 3340 3341 class G1ParVerifyTask: public AbstractGangTask { 3342 private: 3343 G1CollectedHeap* _g1h; 3344 VerifyOption _vo; 3345 bool _failures; 3346 3347 public: 3348 // _vo == UsePrevMarking -> use "prev" marking information, 3349 // _vo == UseNextMarking -> use "next" marking information, 3350 // _vo == UseMarkWord -> use mark word from object header. 3351 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : 3352 AbstractGangTask("Parallel verify task"), 3353 _g1h(g1h), 3354 _vo(vo), 3355 _failures(false) { } 3356 3357 bool failures() { 3358 return _failures; 3359 } 3360 3361 void work(uint worker_id) { 3362 HandleMark hm; 3363 VerifyRegionClosure blk(true, _vo); 3364 _g1h->heap_region_par_iterate_chunked(&blk, worker_id, 3365 _g1h->workers()->active_workers(), 3366 HeapRegion::ParVerifyClaimValue); 3367 if (blk.failures()) { 3368 _failures = true; 3369 } 3370 } 3371 }; 3372 3373 void G1CollectedHeap::verify(bool silent, VerifyOption vo) { 3374 if (SafepointSynchronize::is_at_safepoint()) { 3375 assert(Thread::current()->is_VM_thread(), 3376 "Expected to be executed serially by the VM thread at this point"); 3377 3378 if (!silent) { gclog_or_tty->print("Roots "); } 3379 VerifyRootsClosure rootsCl(vo); 3380 VerifyKlassClosure klassCl(this, &rootsCl); 3381 3382 // We apply the relevant closures to all the oops in the 3383 // system dictionary, class loader data graph and the string table. 3384 // Don't verify the code cache here, since it's verified below. 3385 const int so = SO_AllClasses | SO_Strings; 3386 3387 // Need cleared claim bits for the strong roots processing 3388 ClassLoaderDataGraph::clear_claimed_marks(); 3389 3390 process_strong_roots(true, // activate StrongRootsScope 3391 ScanningOption(so), // roots scanning options 3392 &rootsCl, 3393 &klassCl 3394 ); 3395 3396 // Verify the nmethods in the code cache. 3397 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); 3398 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); 3399 CodeCache::blobs_do(&blobsCl); 3400 3401 bool failures = rootsCl.failures() || codeRootsCl.failures(); 3402 3403 if (vo != VerifyOption_G1UseMarkWord) { 3404 // If we're verifying during a full GC then the region sets 3405 // will have been torn down at the start of the GC. Therefore 3406 // verifying the region sets will fail. So we only verify 3407 // the region sets when not in a full GC. 3408 if (!silent) { gclog_or_tty->print("HeapRegionSets "); } 3409 verify_region_sets(); 3410 } 3411 3412 if (!silent) { gclog_or_tty->print("HeapRegions "); } 3413 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { 3414 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3415 "sanity check"); 3416 3417 G1ParVerifyTask task(this, vo); 3418 assert(UseDynamicNumberOfGCThreads || 3419 workers()->active_workers() == workers()->total_workers(), 3420 "If not dynamic should be using all the workers"); 3421 int n_workers = workers()->active_workers(); 3422 set_par_threads(n_workers); 3423 workers()->run_task(&task); 3424 set_par_threads(0); 3425 if (task.failures()) { 3426 failures = true; 3427 } 3428 3429 // Checks that the expected amount of parallel work was done. 3430 // The implication is that n_workers is > 0. 3431 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue), 3432 "sanity check"); 3433 3434 reset_heap_region_claim_values(); 3435 3436 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3437 "sanity check"); 3438 } else { 3439 VerifyRegionClosure blk(false, vo); 3440 heap_region_iterate(&blk); 3441 if (blk.failures()) { 3442 failures = true; 3443 } 3444 } 3445 if (!silent) gclog_or_tty->print("RemSet "); 3446 rem_set()->verify(); 3447 3448 if (G1StringDedup::is_enabled()) { 3449 if (!silent) gclog_or_tty->print("StrDedup "); 3450 G1StringDedup::verify(); 3451 } 3452 3453 if (failures) { 3454 gclog_or_tty->print_cr("Heap:"); 3455 // It helps to have the per-region information in the output to 3456 // help us track down what went wrong. This is why we call 3457 // print_extended_on() instead of print_on(). 3458 print_extended_on(gclog_or_tty); 3459 gclog_or_tty->print_cr(""); 3460 #ifndef PRODUCT 3461 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { 3462 concurrent_mark()->print_reachable("at-verification-failure", 3463 vo, false /* all */); 3464 } 3465 #endif 3466 gclog_or_tty->flush(); 3467 } 3468 guarantee(!failures, "there should not have been any failures"); 3469 } else { 3470 if (!silent) { 3471 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); 3472 if (G1StringDedup::is_enabled()) { 3473 gclog_or_tty->print(", StrDedup"); 3474 } 3475 gclog_or_tty->print(") "); 3476 } 3477 } 3478 } 3479 3480 void G1CollectedHeap::verify(bool silent) { 3481 verify(silent, VerifyOption_G1UsePrevMarking); 3482 } 3483 3484 double G1CollectedHeap::verify(bool guard, const char* msg) { 3485 double verify_time_ms = 0.0; 3486 3487 if (guard && total_collections() >= VerifyGCStartAt) { 3488 double verify_start = os::elapsedTime(); 3489 HandleMark hm; // Discard invalid handles created during verification 3490 prepare_for_verify(); 3491 Universe::verify(VerifyOption_G1UsePrevMarking, msg); 3492 verify_time_ms = (os::elapsedTime() - verify_start) * 1000; 3493 } 3494 3495 return verify_time_ms; 3496 } 3497 3498 void G1CollectedHeap::verify_before_gc() { 3499 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); 3500 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); 3501 } 3502 3503 void G1CollectedHeap::verify_after_gc() { 3504 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); 3505 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); 3506 } 3507 3508 class PrintRegionClosure: public HeapRegionClosure { 3509 outputStream* _st; 3510 public: 3511 PrintRegionClosure(outputStream* st) : _st(st) {} 3512 bool doHeapRegion(HeapRegion* r) { 3513 r->print_on(_st); 3514 return false; 3515 } 3516 }; 3517 3518 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3519 const HeapRegion* hr, 3520 const VerifyOption vo) const { 3521 switch (vo) { 3522 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 3523 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 3524 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3525 default: ShouldNotReachHere(); 3526 } 3527 return false; // keep some compilers happy 3528 } 3529 3530 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 3531 const VerifyOption vo) const { 3532 switch (vo) { 3533 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 3534 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 3535 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 3536 default: ShouldNotReachHere(); 3537 } 3538 return false; // keep some compilers happy 3539 } 3540 3541 void G1CollectedHeap::print_on(outputStream* st) const { 3542 st->print(" %-20s", "garbage-first heap"); 3543 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 3544 capacity()/K, used_unlocked()/K); 3545 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 3546 _g1_storage.low_boundary(), 3547 _g1_storage.high(), 3548 _g1_storage.high_boundary()); 3549 st->cr(); 3550 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 3551 uint young_regions = _young_list->length(); 3552 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 3553 (size_t) young_regions * HeapRegion::GrainBytes / K); 3554 uint survivor_regions = g1_policy()->recorded_survivor_regions(); 3555 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 3556 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 3557 st->cr(); 3558 MetaspaceAux::print_on(st); 3559 } 3560 3561 void G1CollectedHeap::print_extended_on(outputStream* st) const { 3562 print_on(st); 3563 3564 // Print the per-region information. 3565 st->cr(); 3566 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " 3567 "HS=humongous(starts), HC=humongous(continues), " 3568 "CS=collection set, F=free, TS=gc time stamp, " 3569 "PTAMS=previous top-at-mark-start, " 3570 "NTAMS=next top-at-mark-start)"); 3571 PrintRegionClosure blk(st); 3572 heap_region_iterate(&blk); 3573 } 3574 3575 void G1CollectedHeap::print_on_error(outputStream* st) const { 3576 this->CollectedHeap::print_on_error(st); 3577 3578 if (_cm != NULL) { 3579 st->cr(); 3580 _cm->print_on_error(st); 3581 } 3582 } 3583 3584 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 3585 if (G1CollectedHeap::use_parallel_gc_threads()) { 3586 workers()->print_worker_threads_on(st); 3587 } 3588 _cmThread->print_on(st); 3589 st->cr(); 3590 _cm->print_worker_threads_on(st); 3591 _cg1r->print_worker_threads_on(st); 3592 if (G1StringDedup::is_enabled()) { 3593 G1StringDedup::print_worker_threads_on(st); 3594 } 3595 } 3596 3597 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 3598 if (G1CollectedHeap::use_parallel_gc_threads()) { 3599 workers()->threads_do(tc); 3600 } 3601 tc->do_thread(_cmThread); 3602 _cg1r->threads_do(tc); 3603 if (G1StringDedup::is_enabled()) { 3604 G1StringDedup::threads_do(tc); 3605 } 3606 } 3607 3608 void G1CollectedHeap::print_tracing_info() const { 3609 // We'll overload this to mean "trace GC pause statistics." 3610 if (TraceGen0Time || TraceGen1Time) { 3611 // The "G1CollectorPolicy" is keeping track of these stats, so delegate 3612 // to that. 3613 g1_policy()->print_tracing_info(); 3614 } 3615 if (G1SummarizeRSetStats) { 3616 g1_rem_set()->print_summary_info(); 3617 } 3618 if (G1SummarizeConcMark) { 3619 concurrent_mark()->print_summary_info(); 3620 } 3621 g1_policy()->print_yg_surv_rate_info(); 3622 SpecializationStats::print(); 3623 } 3624 3625 #ifndef PRODUCT 3626 // Helpful for debugging RSet issues. 3627 3628 class PrintRSetsClosure : public HeapRegionClosure { 3629 private: 3630 const char* _msg; 3631 size_t _occupied_sum; 3632 3633 public: 3634 bool doHeapRegion(HeapRegion* r) { 3635 HeapRegionRemSet* hrrs = r->rem_set(); 3636 size_t occupied = hrrs->occupied(); 3637 _occupied_sum += occupied; 3638 3639 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, 3640 HR_FORMAT_PARAMS(r)); 3641 if (occupied == 0) { 3642 gclog_or_tty->print_cr(" RSet is empty"); 3643 } else { 3644 hrrs->print(); 3645 } 3646 gclog_or_tty->print_cr("----------"); 3647 return false; 3648 } 3649 3650 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 3651 gclog_or_tty->cr(); 3652 gclog_or_tty->print_cr("========================================"); 3653 gclog_or_tty->print_cr(msg); 3654 gclog_or_tty->cr(); 3655 } 3656 3657 ~PrintRSetsClosure() { 3658 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); 3659 gclog_or_tty->print_cr("========================================"); 3660 gclog_or_tty->cr(); 3661 } 3662 }; 3663 3664 void G1CollectedHeap::print_cset_rsets() { 3665 PrintRSetsClosure cl("Printing CSet RSets"); 3666 collection_set_iterate(&cl); 3667 } 3668 3669 void G1CollectedHeap::print_all_rsets() { 3670 PrintRSetsClosure cl("Printing All RSets");; 3671 heap_region_iterate(&cl); 3672 } 3673 #endif // PRODUCT 3674 3675 G1CollectedHeap* G1CollectedHeap::heap() { 3676 assert(_sh->kind() == CollectedHeap::G1CollectedHeap, 3677 "not a garbage-first heap"); 3678 return _g1h; 3679 } 3680 3681 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { 3682 // always_do_update_barrier = false; 3683 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 3684 // Fill TLAB's and such 3685 accumulate_statistics_all_tlabs(); 3686 ensure_parsability(true); 3687 3688 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && 3689 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { 3690 g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); 3691 } 3692 } 3693 3694 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) { 3695 3696 if (G1SummarizeRSetStats && 3697 (G1SummarizeRSetStatsPeriod > 0) && 3698 // we are at the end of the GC. Total collections has already been increased. 3699 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { 3700 g1_rem_set()->print_periodic_summary_info("After GC RS summary"); 3701 } 3702 3703 // FIXME: what is this about? 3704 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 3705 // is set. 3706 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), 3707 "derived pointer present")); 3708 // always_do_update_barrier = true; 3709 3710 resize_all_tlabs(); 3711 3712 // We have just completed a GC. Update the soft reference 3713 // policy with the new heap occupancy 3714 Universe::update_heap_info_at_gc(); 3715 } 3716 3717 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 3718 unsigned int gc_count_before, 3719 bool* succeeded, 3720 GCCause::Cause gc_cause) { 3721 assert_heap_not_locked_and_not_at_safepoint(); 3722 g1_policy()->record_stop_world_start(); 3723 VM_G1IncCollectionPause op(gc_count_before, 3724 word_size, 3725 false, /* should_initiate_conc_mark */ 3726 g1_policy()->max_pause_time_ms(), 3727 gc_cause); 3728 VMThread::execute(&op); 3729 3730 HeapWord* result = op.result(); 3731 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 3732 assert(result == NULL || ret_succeeded, 3733 "the result should be NULL if the VM did not succeed"); 3734 *succeeded = ret_succeeded; 3735 3736 assert_heap_not_locked(); 3737 return result; 3738 } 3739 3740 void 3741 G1CollectedHeap::doConcurrentMark() { 3742 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 3743 if (!_cmThread->in_progress()) { 3744 _cmThread->set_started(); 3745 CGC_lock->notify(); 3746 } 3747 } 3748 3749 size_t G1CollectedHeap::pending_card_num() { 3750 size_t extra_cards = 0; 3751 JavaThread *curr = Threads::first(); 3752 while (curr != NULL) { 3753 DirtyCardQueue& dcq = curr->dirty_card_queue(); 3754 extra_cards += dcq.size(); 3755 curr = curr->next(); 3756 } 3757 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 3758 size_t buffer_size = dcqs.buffer_size(); 3759 size_t buffer_num = dcqs.completed_buffers_num(); 3760 3761 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes 3762 // in bytes - not the number of 'entries'. We need to convert 3763 // into a number of cards. 3764 return (buffer_size * buffer_num + extra_cards) / oopSize; 3765 } 3766 3767 size_t G1CollectedHeap::cards_scanned() { 3768 return g1_rem_set()->cardsScanned(); 3769 } 3770 3771 void 3772 G1CollectedHeap::setup_surviving_young_words() { 3773 assert(_surviving_young_words == NULL, "pre-condition"); 3774 uint array_length = g1_policy()->young_cset_region_length(); 3775 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); 3776 if (_surviving_young_words == NULL) { 3777 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, 3778 "Not enough space for young surv words summary."); 3779 } 3780 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); 3781 #ifdef ASSERT 3782 for (uint i = 0; i < array_length; ++i) { 3783 assert( _surviving_young_words[i] == 0, "memset above" ); 3784 } 3785 #endif // !ASSERT 3786 } 3787 3788 void 3789 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { 3790 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3791 uint array_length = g1_policy()->young_cset_region_length(); 3792 for (uint i = 0; i < array_length; ++i) { 3793 _surviving_young_words[i] += surv_young_words[i]; 3794 } 3795 } 3796 3797 void 3798 G1CollectedHeap::cleanup_surviving_young_words() { 3799 guarantee( _surviving_young_words != NULL, "pre-condition" ); 3800 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC); 3801 _surviving_young_words = NULL; 3802 } 3803 3804 #ifdef ASSERT 3805 class VerifyCSetClosure: public HeapRegionClosure { 3806 public: 3807 bool doHeapRegion(HeapRegion* hr) { 3808 // Here we check that the CSet region's RSet is ready for parallel 3809 // iteration. The fields that we'll verify are only manipulated 3810 // when the region is part of a CSet and is collected. Afterwards, 3811 // we reset these fields when we clear the region's RSet (when the 3812 // region is freed) so they are ready when the region is 3813 // re-allocated. The only exception to this is if there's an 3814 // evacuation failure and instead of freeing the region we leave 3815 // it in the heap. In that case, we reset these fields during 3816 // evacuation failure handling. 3817 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); 3818 3819 // Here's a good place to add any other checks we'd like to 3820 // perform on CSet regions. 3821 return false; 3822 } 3823 }; 3824 #endif // ASSERT 3825 3826 #if TASKQUEUE_STATS 3827 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 3828 st->print_raw_cr("GC Task Stats"); 3829 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 3830 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 3831 } 3832 3833 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { 3834 print_taskqueue_stats_hdr(st); 3835 3836 TaskQueueStats totals; 3837 const int n = workers() != NULL ? workers()->total_workers() : 1; 3838 for (int i = 0; i < n; ++i) { 3839 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); 3840 totals += task_queue(i)->stats; 3841 } 3842 st->print_raw("tot "); totals.print(st); st->cr(); 3843 3844 DEBUG_ONLY(totals.verify()); 3845 } 3846 3847 void G1CollectedHeap::reset_taskqueue_stats() { 3848 const int n = workers() != NULL ? workers()->total_workers() : 1; 3849 for (int i = 0; i < n; ++i) { 3850 task_queue(i)->stats.reset(); 3851 } 3852 } 3853 #endif // TASKQUEUE_STATS 3854 3855 void G1CollectedHeap::log_gc_header() { 3856 if (!G1Log::fine()) { 3857 return; 3858 } 3859 3860 gclog_or_tty->date_stamp(PrintGCDateStamps); 3861 gclog_or_tty->stamp(PrintGCTimeStamps); 3862 3863 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) 3864 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") 3865 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); 3866 3867 gclog_or_tty->print("[%s", (const char*)gc_cause_str); 3868 } 3869 3870 void G1CollectedHeap::log_gc_footer(double pause_time_sec) { 3871 if (!G1Log::fine()) { 3872 return; 3873 } 3874 3875 if (G1Log::finer()) { 3876 if (evacuation_failed()) { 3877 gclog_or_tty->print(" (to-space exhausted)"); 3878 } 3879 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3880 g1_policy()->phase_times()->note_gc_end(); 3881 g1_policy()->phase_times()->print(pause_time_sec); 3882 g1_policy()->print_detailed_heap_transition(); 3883 } else { 3884 if (evacuation_failed()) { 3885 gclog_or_tty->print("--"); 3886 } 3887 g1_policy()->print_heap_transition(); 3888 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); 3889 } 3890 gclog_or_tty->flush(); 3891 } 3892 3893 bool 3894 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3895 assert_at_safepoint(true /* should_be_vm_thread */); 3896 guarantee(!is_gc_active(), "collection is not reentrant"); 3897 3898 if (GC_locker::check_active_before_gc()) { 3899 return false; 3900 } 3901 3902 _gc_timer_stw->register_gc_start(); 3903 3904 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3905 3906 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3907 ResourceMark rm; 3908 3909 print_heap_before_gc(); 3910 trace_heap_before_gc(_gc_tracer_stw); 3911 3912 verify_region_sets_optional(); 3913 verify_dirty_young_regions(); 3914 3915 // This call will decide whether this pause is an initial-mark 3916 // pause. If it is, during_initial_mark_pause() will return true 3917 // for the duration of this pause. 3918 g1_policy()->decide_on_conc_mark_initiation(); 3919 3920 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3921 assert(!g1_policy()->during_initial_mark_pause() || 3922 g1_policy()->gcs_are_young(), "sanity"); 3923 3924 // We also do not allow mixed GCs during marking. 3925 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); 3926 3927 // Record whether this pause is an initial mark. When the current 3928 // thread has completed its logging output and it's safe to signal 3929 // the CM thread, the flag's value in the policy has been reset. 3930 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); 3931 3932 // Inner scope for scope based logging, timers, and stats collection 3933 { 3934 EvacuationInfo evacuation_info; 3935 3936 if (g1_policy()->during_initial_mark_pause()) { 3937 // We are about to start a marking cycle, so we increment the 3938 // full collection counter. 3939 increment_old_marking_cycles_started(); 3940 register_concurrent_cycle_start(_gc_timer_stw->gc_start()); 3941 } 3942 3943 _gc_tracer_stw->report_yc_type(yc_type()); 3944 3945 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); 3946 3947 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 3948 workers()->active_workers() : 1); 3949 double pause_start_sec = os::elapsedTime(); 3950 g1_policy()->phase_times()->note_gc_start(active_workers); 3951 log_gc_header(); 3952 3953 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 3954 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); 3955 3956 // If the secondary_free_list is not empty, append it to the 3957 // free_list. No need to wait for the cleanup operation to finish; 3958 // the region allocation code will check the secondary_free_list 3959 // and wait if necessary. If the G1StressConcRegionFreeing flag is 3960 // set, skip this step so that the region allocation code has to 3961 // get entries from the secondary_free_list. 3962 if (!G1StressConcRegionFreeing) { 3963 append_secondary_free_list_if_not_empty_with_lock(); 3964 } 3965 3966 assert(check_young_list_well_formed(), "young list should be well formed"); 3967 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), 3968 "sanity check"); 3969 3970 // Don't dynamically change the number of GC threads this early. A value of 3971 // 0 is used to indicate serial work. When parallel work is done, 3972 // it will be set. 3973 3974 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 3975 IsGCActiveMark x; 3976 3977 gc_prologue(false); 3978 increment_total_collections(false /* full gc */); 3979 increment_gc_time_stamp(); 3980 3981 verify_before_gc(); 3982 3983 COMPILER2_PRESENT(DerivedPointerTable::clear()); 3984 3985 // Please see comment in g1CollectedHeap.hpp and 3986 // G1CollectedHeap::ref_processing_init() to see how 3987 // reference processing currently works in G1. 3988 3989 // Enable discovery in the STW reference processor 3990 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, 3991 true /*verify_no_refs*/); 3992 3993 { 3994 // We want to temporarily turn off discovery by the 3995 // CM ref processor, if necessary, and turn it back on 3996 // on again later if we do. Using a scoped 3997 // NoRefDiscovery object will do this. 3998 NoRefDiscovery no_cm_discovery(ref_processor_cm()); 3999 4000 // Forget the current alloc region (we might even choose it to be part 4001 // of the collection set!). 4002 release_mutator_alloc_region(); 4003 4004 // We should call this after we retire the mutator alloc 4005 // region(s) so that all the ALLOC / RETIRE events are generated 4006 // before the start GC event. 4007 _hr_printer.start_gc(false /* full */, (size_t) total_collections()); 4008 4009 // This timing is only used by the ergonomics to handle our pause target. 4010 // It is unclear why this should not include the full pause. We will 4011 // investigate this in CR 7178365. 4012 // 4013 // Preserving the old comment here if that helps the investigation: 4014 // 4015 // The elapsed time induced by the start time below deliberately elides 4016 // the possible verification above. 4017 double sample_start_time_sec = os::elapsedTime(); 4018 4019 #if YOUNG_LIST_VERBOSE 4020 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); 4021 _young_list->print(); 4022 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4023 #endif // YOUNG_LIST_VERBOSE 4024 4025 g1_policy()->record_collection_pause_start(sample_start_time_sec); 4026 4027 double scan_wait_start = os::elapsedTime(); 4028 // We have to wait until the CM threads finish scanning the 4029 // root regions as it's the only way to ensure that all the 4030 // objects on them have been correctly scanned before we start 4031 // moving them during the GC. 4032 bool waited = _cm->root_regions()->wait_until_scan_finished(); 4033 double wait_time_ms = 0.0; 4034 if (waited) { 4035 double scan_wait_end = os::elapsedTime(); 4036 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 4037 } 4038 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 4039 4040 #if YOUNG_LIST_VERBOSE 4041 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); 4042 _young_list->print(); 4043 #endif // YOUNG_LIST_VERBOSE 4044 4045 if (g1_policy()->during_initial_mark_pause()) { 4046 concurrent_mark()->checkpointRootsInitialPre(); 4047 } 4048 4049 #if YOUNG_LIST_VERBOSE 4050 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); 4051 _young_list->print(); 4052 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4053 #endif // YOUNG_LIST_VERBOSE 4054 4055 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); 4056 4057 _cm->note_start_of_gc(); 4058 // We should not verify the per-thread SATB buffers given that 4059 // we have not filtered them yet (we'll do so during the 4060 // GC). We also call this after finalize_cset() to 4061 // ensure that the CSet has been finalized. 4062 _cm->verify_no_cset_oops(true /* verify_stacks */, 4063 true /* verify_enqueued_buffers */, 4064 false /* verify_thread_buffers */, 4065 true /* verify_fingers */); 4066 4067 if (_hr_printer.is_active()) { 4068 HeapRegion* hr = g1_policy()->collection_set(); 4069 while (hr != NULL) { 4070 G1HRPrinter::RegionType type; 4071 if (!hr->is_young()) { 4072 type = G1HRPrinter::Old; 4073 } else if (hr->is_survivor()) { 4074 type = G1HRPrinter::Survivor; 4075 } else { 4076 type = G1HRPrinter::Eden; 4077 } 4078 _hr_printer.cset(hr); 4079 hr = hr->next_in_collection_set(); 4080 } 4081 } 4082 4083 #ifdef ASSERT 4084 VerifyCSetClosure cl; 4085 collection_set_iterate(&cl); 4086 #endif // ASSERT 4087 4088 setup_surviving_young_words(); 4089 4090 // Initialize the GC alloc regions. 4091 init_gc_alloc_regions(evacuation_info); 4092 4093 // Actually do the work... 4094 evacuate_collection_set(evacuation_info); 4095 4096 // We do this to mainly verify the per-thread SATB buffers 4097 // (which have been filtered by now) since we didn't verify 4098 // them earlier. No point in re-checking the stacks / enqueued 4099 // buffers given that the CSet has not changed since last time 4100 // we checked. 4101 _cm->verify_no_cset_oops(false /* verify_stacks */, 4102 false /* verify_enqueued_buffers */, 4103 true /* verify_thread_buffers */, 4104 true /* verify_fingers */); 4105 4106 free_collection_set(g1_policy()->collection_set(), evacuation_info); 4107 g1_policy()->clear_collection_set(); 4108 4109 cleanup_surviving_young_words(); 4110 4111 // Start a new incremental collection set for the next pause. 4112 g1_policy()->start_incremental_cset_building(); 4113 4114 clear_cset_fast_test(); 4115 4116 _young_list->reset_sampled_info(); 4117 4118 // Don't check the whole heap at this point as the 4119 // GC alloc regions from this pause have been tagged 4120 // as survivors and moved on to the survivor list. 4121 // Survivor regions will fail the !is_young() check. 4122 assert(check_young_list_empty(false /* check_heap */), 4123 "young list should be empty"); 4124 4125 #if YOUNG_LIST_VERBOSE 4126 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); 4127 _young_list->print(); 4128 #endif // YOUNG_LIST_VERBOSE 4129 4130 g1_policy()->record_survivor_regions(_young_list->survivor_length(), 4131 _young_list->first_survivor_region(), 4132 _young_list->last_survivor_region()); 4133 4134 _young_list->reset_auxilary_lists(); 4135 4136 if (evacuation_failed()) { 4137 _summary_bytes_used = recalculate_used(); 4138 uint n_queues = MAX2((int)ParallelGCThreads, 1); 4139 for (uint i = 0; i < n_queues; i++) { 4140 if (_evacuation_failed_info_array[i].has_failed()) { 4141 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 4142 } 4143 } 4144 } else { 4145 // The "used" of the the collection set have already been subtracted 4146 // when they were freed. Add in the bytes evacuated. 4147 _summary_bytes_used += g1_policy()->bytes_copied_during_gc(); 4148 } 4149 4150 if (g1_policy()->during_initial_mark_pause()) { 4151 // We have to do this before we notify the CM threads that 4152 // they can start working to make sure that all the 4153 // appropriate initialization is done on the CM object. 4154 concurrent_mark()->checkpointRootsInitialPost(); 4155 set_marking_started(); 4156 // Note that we don't actually trigger the CM thread at 4157 // this point. We do that later when we're sure that 4158 // the current thread has completed its logging output. 4159 } 4160 4161 allocate_dummy_regions(); 4162 4163 #if YOUNG_LIST_VERBOSE 4164 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); 4165 _young_list->print(); 4166 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); 4167 #endif // YOUNG_LIST_VERBOSE 4168 4169 init_mutator_alloc_region(); 4170 4171 { 4172 size_t expand_bytes = g1_policy()->expansion_amount(); 4173 if (expand_bytes > 0) { 4174 size_t bytes_before = capacity(); 4175 // No need for an ergo verbose message here, 4176 // expansion_amount() does this when it returns a value > 0. 4177 if (!expand(expand_bytes)) { 4178 // We failed to expand the heap so let's verify that 4179 // committed/uncommitted amount match the backing store 4180 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch"); 4181 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch"); 4182 } 4183 } 4184 } 4185 4186 // We redo the verification but now wrt to the new CSet which 4187 // has just got initialized after the previous CSet was freed. 4188 _cm->verify_no_cset_oops(true /* verify_stacks */, 4189 true /* verify_enqueued_buffers */, 4190 true /* verify_thread_buffers */, 4191 true /* verify_fingers */); 4192 _cm->note_end_of_gc(); 4193 4194 // This timing is only used by the ergonomics to handle our pause target. 4195 // It is unclear why this should not include the full pause. We will 4196 // investigate this in CR 7178365. 4197 double sample_end_time_sec = os::elapsedTime(); 4198 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 4199 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); 4200 4201 MemoryService::track_memory_usage(); 4202 4203 // In prepare_for_verify() below we'll need to scan the deferred 4204 // update buffers to bring the RSets up-to-date if 4205 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning 4206 // the update buffers we'll probably need to scan cards on the 4207 // regions we just allocated to (i.e., the GC alloc 4208 // regions). However, during the last GC we called 4209 // set_saved_mark() on all the GC alloc regions, so card 4210 // scanning might skip the [saved_mark_word()...top()] area of 4211 // those regions (i.e., the area we allocated objects into 4212 // during the last GC). But it shouldn't. Given that 4213 // saved_mark_word() is conditional on whether the GC time stamp 4214 // on the region is current or not, by incrementing the GC time 4215 // stamp here we invalidate all the GC time stamps on all the 4216 // regions and saved_mark_word() will simply return top() for 4217 // all the regions. This is a nicer way of ensuring this rather 4218 // than iterating over the regions and fixing them. In fact, the 4219 // GC time stamp increment here also ensures that 4220 // saved_mark_word() will return top() between pauses, i.e., 4221 // during concurrent refinement. So we don't need the 4222 // is_gc_active() check to decided which top to use when 4223 // scanning cards (see CR 7039627). 4224 increment_gc_time_stamp(); 4225 4226 verify_after_gc(); 4227 4228 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); 4229 ref_processor_stw()->verify_no_references_recorded(); 4230 4231 // CM reference discovery will be re-enabled if necessary. 4232 } 4233 4234 // We should do this after we potentially expand the heap so 4235 // that all the COMMIT events are generated before the end GC 4236 // event, and after we retire the GC alloc regions so that all 4237 // RETIRE events are generated before the end GC event. 4238 _hr_printer.end_gc(false /* full */, (size_t) total_collections()); 4239 4240 if (mark_in_progress()) { 4241 concurrent_mark()->update_g1_committed(); 4242 } 4243 4244 #ifdef TRACESPINNING 4245 ParallelTaskTerminator::print_termination_counts(); 4246 #endif 4247 4248 gc_epilogue(false); 4249 } 4250 4251 // Print the remainder of the GC log output. 4252 log_gc_footer(os::elapsedTime() - pause_start_sec); 4253 4254 // It is not yet to safe to tell the concurrent mark to 4255 // start as we have some optional output below. We don't want the 4256 // output from the concurrent mark thread interfering with this 4257 // logging output either. 4258 4259 _hrs.verify_optional(); 4260 verify_region_sets_optional(); 4261 4262 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats()); 4263 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 4264 4265 print_heap_after_gc(); 4266 trace_heap_after_gc(_gc_tracer_stw); 4267 4268 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 4269 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 4270 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 4271 // before any GC notifications are raised. 4272 g1mm()->update_sizes(); 4273 4274 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 4275 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 4276 _gc_timer_stw->register_gc_end(); 4277 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 4278 } 4279 // It should now be safe to tell the concurrent mark thread to start 4280 // without its logging output interfering with the logging output 4281 // that came from the pause. 4282 4283 if (should_start_conc_mark) { 4284 // CAUTION: after the doConcurrentMark() call below, 4285 // the concurrent marking thread(s) could be running 4286 // concurrently with us. Make sure that anything after 4287 // this point does not assume that we are the only GC thread 4288 // running. Note: of course, the actual marking work will 4289 // not start until the safepoint itself is released in 4290 // SuspendibleThreadSet::desynchronize(). 4291 doConcurrentMark(); 4292 } 4293 4294 return true; 4295 } 4296 4297 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose) 4298 { 4299 size_t gclab_word_size; 4300 switch (purpose) { 4301 case GCAllocForSurvived: 4302 gclab_word_size = _survivor_plab_stats.desired_plab_sz(); 4303 break; 4304 case GCAllocForTenured: 4305 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4306 break; 4307 default: 4308 assert(false, "unknown GCAllocPurpose"); 4309 gclab_word_size = _old_plab_stats.desired_plab_sz(); 4310 break; 4311 } 4312 4313 // Prevent humongous PLAB sizes for two reasons: 4314 // * PLABs are allocated using a similar paths as oops, but should 4315 // never be in a humongous region 4316 // * Allowing humongous PLABs needlessly churns the region free lists 4317 return MIN2(_humongous_object_threshold_in_words, gclab_word_size); 4318 } 4319 4320 void G1CollectedHeap::init_mutator_alloc_region() { 4321 assert(_mutator_alloc_region.get() == NULL, "pre-condition"); 4322 _mutator_alloc_region.init(); 4323 } 4324 4325 void G1CollectedHeap::release_mutator_alloc_region() { 4326 _mutator_alloc_region.release(); 4327 assert(_mutator_alloc_region.get() == NULL, "post-condition"); 4328 } 4329 4330 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) { 4331 assert_at_safepoint(true /* should_be_vm_thread */); 4332 4333 _survivor_gc_alloc_region.init(); 4334 _old_gc_alloc_region.init(); 4335 HeapRegion* retained_region = _retained_old_gc_alloc_region; 4336 _retained_old_gc_alloc_region = NULL; 4337 4338 // We will discard the current GC alloc region if: 4339 // a) it's in the collection set (it can happen!), 4340 // b) it's already full (no point in using it), 4341 // c) it's empty (this means that it was emptied during 4342 // a cleanup and it should be on the free list now), or 4343 // d) it's humongous (this means that it was emptied 4344 // during a cleanup and was added to the free list, but 4345 // has been subsequently used to allocate a humongous 4346 // object that may be less than the region size). 4347 if (retained_region != NULL && 4348 !retained_region->in_collection_set() && 4349 !(retained_region->top() == retained_region->end()) && 4350 !retained_region->is_empty() && 4351 !retained_region->isHumongous()) { 4352 retained_region->set_saved_mark(); 4353 // The retained region was added to the old region set when it was 4354 // retired. We have to remove it now, since we don't allow regions 4355 // we allocate to in the region sets. We'll re-add it later, when 4356 // it's retired again. 4357 _old_set.remove(retained_region); 4358 bool during_im = g1_policy()->during_initial_mark_pause(); 4359 retained_region->note_start_of_copying(during_im); 4360 _old_gc_alloc_region.set(retained_region); 4361 _hr_printer.reuse(retained_region); 4362 evacuation_info.set_alloc_regions_used_before(retained_region->used()); 4363 } 4364 } 4365 4366 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) { 4367 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() + 4368 _old_gc_alloc_region.count()); 4369 _survivor_gc_alloc_region.release(); 4370 // If we have an old GC alloc region to release, we'll save it in 4371 // _retained_old_gc_alloc_region. If we don't 4372 // _retained_old_gc_alloc_region will become NULL. This is what we 4373 // want either way so no reason to check explicitly for either 4374 // condition. 4375 _retained_old_gc_alloc_region = _old_gc_alloc_region.release(); 4376 4377 if (ResizePLAB) { 4378 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4379 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers); 4380 } 4381 } 4382 4383 void G1CollectedHeap::abandon_gc_alloc_regions() { 4384 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition"); 4385 assert(_old_gc_alloc_region.get() == NULL, "pre-condition"); 4386 _retained_old_gc_alloc_region = NULL; 4387 } 4388 4389 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { 4390 _drain_in_progress = false; 4391 set_evac_failure_closure(cl); 4392 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true); 4393 } 4394 4395 void G1CollectedHeap::finalize_for_evac_failure() { 4396 assert(_evac_failure_scan_stack != NULL && 4397 _evac_failure_scan_stack->length() == 0, 4398 "Postcondition"); 4399 assert(!_drain_in_progress, "Postcondition"); 4400 delete _evac_failure_scan_stack; 4401 _evac_failure_scan_stack = NULL; 4402 } 4403 4404 void G1CollectedHeap::remove_self_forwarding_pointers() { 4405 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4406 4407 double remove_self_forwards_start = os::elapsedTime(); 4408 4409 G1ParRemoveSelfForwardPtrsTask rsfp_task(this); 4410 4411 if (G1CollectedHeap::use_parallel_gc_threads()) { 4412 set_par_threads(); 4413 workers()->run_task(&rsfp_task); 4414 set_par_threads(0); 4415 } else { 4416 rsfp_task.work(0); 4417 } 4418 4419 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity"); 4420 4421 // Reset the claim values in the regions in the collection set. 4422 reset_cset_heap_region_claim_values(); 4423 4424 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity"); 4425 4426 // Now restore saved marks, if any. 4427 assert(_objs_with_preserved_marks.size() == 4428 _preserved_marks_of_objs.size(), "Both or none."); 4429 while (!_objs_with_preserved_marks.is_empty()) { 4430 oop obj = _objs_with_preserved_marks.pop(); 4431 markOop m = _preserved_marks_of_objs.pop(); 4432 obj->set_mark(m); 4433 } 4434 _objs_with_preserved_marks.clear(true); 4435 _preserved_marks_of_objs.clear(true); 4436 4437 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 4438 } 4439 4440 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { 4441 _evac_failure_scan_stack->push(obj); 4442 } 4443 4444 void G1CollectedHeap::drain_evac_failure_scan_stack() { 4445 assert(_evac_failure_scan_stack != NULL, "precondition"); 4446 4447 while (_evac_failure_scan_stack->length() > 0) { 4448 oop obj = _evac_failure_scan_stack->pop(); 4449 _evac_failure_closure->set_region(heap_region_containing(obj)); 4450 obj->oop_iterate_backwards(_evac_failure_closure); 4451 } 4452 } 4453 4454 oop 4455 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, 4456 oop old) { 4457 assert(obj_in_cs(old), 4458 err_msg("obj: "PTR_FORMAT" should still be in the CSet", 4459 (HeapWord*) old)); 4460 markOop m = old->mark(); 4461 oop forward_ptr = old->forward_to_atomic(old); 4462 if (forward_ptr == NULL) { 4463 // Forward-to-self succeeded. 4464 assert(_par_scan_state != NULL, "par scan state"); 4465 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); 4466 uint queue_num = _par_scan_state->queue_num(); 4467 4468 _evacuation_failed = true; 4469 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); 4470 if (_evac_failure_closure != cl) { 4471 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); 4472 assert(!_drain_in_progress, 4473 "Should only be true while someone holds the lock."); 4474 // Set the global evac-failure closure to the current thread's. 4475 assert(_evac_failure_closure == NULL, "Or locking has failed."); 4476 set_evac_failure_closure(cl); 4477 // Now do the common part. 4478 handle_evacuation_failure_common(old, m); 4479 // Reset to NULL. 4480 set_evac_failure_closure(NULL); 4481 } else { 4482 // The lock is already held, and this is recursive. 4483 assert(_drain_in_progress, "This should only be the recursive case."); 4484 handle_evacuation_failure_common(old, m); 4485 } 4486 return old; 4487 } else { 4488 // Forward-to-self failed. Either someone else managed to allocate 4489 // space for this object (old != forward_ptr) or they beat us in 4490 // self-forwarding it (old == forward_ptr). 4491 assert(old == forward_ptr || !obj_in_cs(forward_ptr), 4492 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " 4493 "should not be in the CSet", 4494 (HeapWord*) old, (HeapWord*) forward_ptr)); 4495 return forward_ptr; 4496 } 4497 } 4498 4499 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { 4500 preserve_mark_if_necessary(old, m); 4501 4502 HeapRegion* r = heap_region_containing(old); 4503 if (!r->evacuation_failed()) { 4504 r->set_evacuation_failed(true); 4505 _hr_printer.evac_failure(r); 4506 } 4507 4508 push_on_evac_failure_scan_stack(old); 4509 4510 if (!_drain_in_progress) { 4511 // prevent recursion in copy_to_survivor_space() 4512 _drain_in_progress = true; 4513 drain_evac_failure_scan_stack(); 4514 _drain_in_progress = false; 4515 } 4516 } 4517 4518 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { 4519 assert(evacuation_failed(), "Oversaving!"); 4520 // We want to call the "for_promotion_failure" version only in the 4521 // case of a promotion failure. 4522 if (m->must_be_preserved_for_promotion_failure(obj)) { 4523 _objs_with_preserved_marks.push(obj); 4524 _preserved_marks_of_objs.push(m); 4525 } 4526 } 4527 4528 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose, 4529 size_t word_size) { 4530 if (purpose == GCAllocForSurvived) { 4531 HeapWord* result = survivor_attempt_allocation(word_size); 4532 if (result != NULL) { 4533 return result; 4534 } else { 4535 // Let's try to allocate in the old gen in case we can fit the 4536 // object there. 4537 return old_attempt_allocation(word_size); 4538 } 4539 } else { 4540 assert(purpose == GCAllocForTenured, "sanity"); 4541 HeapWord* result = old_attempt_allocation(word_size); 4542 if (result != NULL) { 4543 return result; 4544 } else { 4545 // Let's try to allocate in the survivors in case we can fit the 4546 // object there. 4547 return survivor_attempt_allocation(word_size); 4548 } 4549 } 4550 4551 ShouldNotReachHere(); 4552 // Trying to keep some compilers happy. 4553 return NULL; 4554 } 4555 4556 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) : 4557 ParGCAllocBuffer(gclab_word_size), _retired(true) { } 4558 4559 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp) 4560 : _g1h(g1h), 4561 _refs(g1h->task_queue(queue_num)), 4562 _dcq(&g1h->dirty_card_queue_set()), 4563 _ct_bs(g1h->g1_barrier_set()), 4564 _g1_rem(g1h->g1_rem_set()), 4565 _hash_seed(17), _queue_num(queue_num), 4566 _term_attempts(0), 4567 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)), 4568 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)), 4569 _age_table(false), _scanner(g1h, this, rp), 4570 _strong_roots_time(0), _term_time(0), 4571 _alloc_buffer_waste(0), _undo_waste(0) { 4572 // we allocate G1YoungSurvRateNumRegions plus one entries, since 4573 // we "sacrifice" entry 0 to keep track of surviving bytes for 4574 // non-young regions (where the age is -1) 4575 // We also add a few elements at the beginning and at the end in 4576 // an attempt to eliminate cache contention 4577 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length(); 4578 uint array_length = PADDING_ELEM_NUM + 4579 real_length + 4580 PADDING_ELEM_NUM; 4581 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC); 4582 if (_surviving_young_words_base == NULL) 4583 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR, 4584 "Not enough space for young surv histo."); 4585 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM; 4586 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t)); 4587 4588 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer; 4589 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer; 4590 4591 _start = os::elapsedTime(); 4592 } 4593 4594 void 4595 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st) 4596 { 4597 st->print_raw_cr("GC Termination Stats"); 4598 st->print_raw_cr(" elapsed --strong roots-- -------termination-------" 4599 " ------waste (KiB)------"); 4600 st->print_raw_cr("thr ms ms % ms % attempts" 4601 " total alloc undo"); 4602 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------" 4603 " ------- ------- -------"); 4604 } 4605 4606 void 4607 G1ParScanThreadState::print_termination_stats(int i, 4608 outputStream* const st) const 4609 { 4610 const double elapsed_ms = elapsed_time() * 1000.0; 4611 const double s_roots_ms = strong_roots_time() * 1000.0; 4612 const double term_ms = term_time() * 1000.0; 4613 st->print_cr("%3d %9.2f %9.2f %6.2f " 4614 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 4615 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 4616 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms, 4617 term_ms, term_ms * 100 / elapsed_ms, term_attempts(), 4618 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K, 4619 alloc_buffer_waste() * HeapWordSize / K, 4620 undo_waste() * HeapWordSize / K); 4621 } 4622 4623 #ifdef ASSERT 4624 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const { 4625 assert(ref != NULL, "invariant"); 4626 assert(UseCompressedOops, "sanity"); 4627 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref)); 4628 oop p = oopDesc::load_decode_heap_oop(ref); 4629 assert(_g1h->is_in_g1_reserved(p), 4630 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p)); 4631 return true; 4632 } 4633 4634 bool G1ParScanThreadState::verify_ref(oop* ref) const { 4635 assert(ref != NULL, "invariant"); 4636 if (has_partial_array_mask(ref)) { 4637 // Must be in the collection set--it's already been copied. 4638 oop p = clear_partial_array_mask(ref); 4639 assert(_g1h->obj_in_cs(p), 4640 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p)); 4641 } else { 4642 oop p = oopDesc::load_decode_heap_oop(ref); 4643 assert(_g1h->is_in_g1_reserved(p), 4644 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p)); 4645 } 4646 return true; 4647 } 4648 4649 bool G1ParScanThreadState::verify_task(StarTask ref) const { 4650 if (ref.is_narrow()) { 4651 return verify_ref((narrowOop*) ref); 4652 } else { 4653 return verify_ref((oop*) ref); 4654 } 4655 } 4656 #endif // ASSERT 4657 4658 void G1ParScanThreadState::trim_queue() { 4659 assert(_evac_failure_cl != NULL, "not set"); 4660 4661 StarTask ref; 4662 do { 4663 // Drain the overflow stack first, so other threads can steal. 4664 while (refs()->pop_overflow(ref)) { 4665 deal_with_reference(ref); 4666 } 4667 4668 while (refs()->pop_local(ref)) { 4669 deal_with_reference(ref); 4670 } 4671 } while (!refs()->is_empty()); 4672 } 4673 4674 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, 4675 G1ParScanThreadState* par_scan_state) : 4676 _g1(g1), _par_scan_state(par_scan_state), 4677 _worker_id(par_scan_state->queue_num()) { } 4678 4679 void G1ParCopyHelper::mark_object(oop obj) { 4680 #ifdef ASSERT 4681 HeapRegion* hr = _g1->heap_region_containing(obj); 4682 assert(hr != NULL, "sanity"); 4683 assert(!hr->in_collection_set(), "should not mark objects in the CSet"); 4684 #endif // ASSERT 4685 4686 // We know that the object is not moving so it's safe to read its size. 4687 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 4688 } 4689 4690 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { 4691 #ifdef ASSERT 4692 assert(from_obj->is_forwarded(), "from obj should be forwarded"); 4693 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); 4694 assert(from_obj != to_obj, "should not be self-forwarded"); 4695 4696 HeapRegion* from_hr = _g1->heap_region_containing(from_obj); 4697 assert(from_hr != NULL, "sanity"); 4698 assert(from_hr->in_collection_set(), "from obj should be in the CSet"); 4699 4700 HeapRegion* to_hr = _g1->heap_region_containing(to_obj); 4701 assert(to_hr != NULL, "sanity"); 4702 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet"); 4703 #endif // ASSERT 4704 4705 // The object might be in the process of being copied by another 4706 // worker so we cannot trust that its to-space image is 4707 // well-formed. So we have to read its size from its from-space 4708 // image which we know should not be changing. 4709 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); 4710 } 4711 4712 oop G1ParScanThreadState::copy_to_survivor_space(oop const old) { 4713 size_t word_sz = old->size(); 4714 HeapRegion* from_region = _g1h->heap_region_containing_raw(old); 4715 // +1 to make the -1 indexes valid... 4716 int young_index = from_region->young_index_in_cset()+1; 4717 assert( (from_region->is_young() && young_index > 0) || 4718 (!from_region->is_young() && young_index == 0), "invariant" ); 4719 G1CollectorPolicy* g1p = _g1h->g1_policy(); 4720 markOop m = old->mark(); 4721 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age() 4722 : m->age(); 4723 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age, 4724 word_sz); 4725 HeapWord* obj_ptr = allocate(alloc_purpose, word_sz); 4726 #ifndef PRODUCT 4727 // Should this evacuation fail? 4728 if (_g1h->evacuation_should_fail()) { 4729 if (obj_ptr != NULL) { 4730 undo_allocation(alloc_purpose, obj_ptr, word_sz); 4731 obj_ptr = NULL; 4732 } 4733 } 4734 #endif // !PRODUCT 4735 4736 if (obj_ptr == NULL) { 4737 // This will either forward-to-self, or detect that someone else has 4738 // installed a forwarding pointer. 4739 return _g1h->handle_evacuation_failure_par(this, old); 4740 } 4741 4742 oop obj = oop(obj_ptr); 4743 4744 // We're going to allocate linearly, so might as well prefetch ahead. 4745 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes); 4746 4747 oop forward_ptr = old->forward_to_atomic(obj); 4748 if (forward_ptr == NULL) { 4749 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz); 4750 4751 // alloc_purpose is just a hint to allocate() above, recheck the type of region 4752 // we actually allocated from and update alloc_purpose accordingly 4753 HeapRegion* to_region = _g1h->heap_region_containing_raw(obj_ptr); 4754 alloc_purpose = to_region->is_young() ? GCAllocForSurvived : GCAllocForTenured; 4755 4756 if (g1p->track_object_age(alloc_purpose)) { 4757 // We could simply do obj->incr_age(). However, this causes a 4758 // performance issue. obj->incr_age() will first check whether 4759 // the object has a displaced mark by checking its mark word; 4760 // getting the mark word from the new location of the object 4761 // stalls. So, given that we already have the mark word and we 4762 // are about to install it anyway, it's better to increase the 4763 // age on the mark word, when the object does not have a 4764 // displaced mark word. We're not expecting many objects to have 4765 // a displaced marked word, so that case is not optimized 4766 // further (it could be...) and we simply call obj->incr_age(). 4767 4768 if (m->has_displaced_mark_helper()) { 4769 // in this case, we have to install the mark word first, 4770 // otherwise obj looks to be forwarded (the old mark word, 4771 // which contains the forward pointer, was copied) 4772 obj->set_mark(m); 4773 obj->incr_age(); 4774 } else { 4775 m = m->incr_age(); 4776 obj->set_mark(m); 4777 } 4778 age_table()->add(obj, word_sz); 4779 } else { 4780 obj->set_mark(m); 4781 } 4782 4783 if (G1StringDedup::is_enabled()) { 4784 G1StringDedup::enqueue_from_evacuation(from_region->is_young(), 4785 to_region->is_young(), 4786 queue_num(), 4787 obj); 4788 } 4789 4790 size_t* surv_young_words = surviving_young_words(); 4791 surv_young_words[young_index] += word_sz; 4792 4793 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) { 4794 // We keep track of the next start index in the length field of 4795 // the to-space object. The actual length can be found in the 4796 // length field of the from-space object. 4797 arrayOop(obj)->set_length(0); 4798 oop* old_p = set_partial_array_mask(old); 4799 push_on_queue(old_p); 4800 } else { 4801 // No point in using the slower heap_region_containing() method, 4802 // given that we know obj is in the heap. 4803 _scanner.set_region(_g1h->heap_region_containing_raw(obj)); 4804 obj->oop_iterate_backwards(&_scanner); 4805 } 4806 } else { 4807 undo_allocation(alloc_purpose, obj_ptr, word_sz); 4808 obj = forward_ptr; 4809 } 4810 return obj; 4811 } 4812 4813 template <class T> 4814 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { 4815 if (_g1->heap_region_containing_raw(new_obj)->is_young()) { 4816 _scanned_klass->record_modified_oops(); 4817 } 4818 } 4819 4820 template <G1Barrier barrier, bool do_mark_object> 4821 template <class T> 4822 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) { 4823 T heap_oop = oopDesc::load_heap_oop(p); 4824 4825 if (oopDesc::is_null(heap_oop)) { 4826 return; 4827 } 4828 4829 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 4830 4831 assert(_worker_id == _par_scan_state->queue_num(), "sanity"); 4832 4833 if (_g1->in_cset_fast_test(obj)) { 4834 oop forwardee; 4835 if (obj->is_forwarded()) { 4836 forwardee = obj->forwardee(); 4837 } else { 4838 forwardee = _par_scan_state->copy_to_survivor_space(obj); 4839 } 4840 assert(forwardee != NULL, "forwardee should not be NULL"); 4841 oopDesc::encode_store_heap_oop(p, forwardee); 4842 if (do_mark_object && forwardee != obj) { 4843 // If the object is self-forwarded we don't need to explicitly 4844 // mark it, the evacuation failure protocol will do so. 4845 mark_forwarded_object(obj, forwardee); 4846 } 4847 4848 if (barrier == G1BarrierKlass) { 4849 do_klass_barrier(p, forwardee); 4850 } 4851 } else { 4852 // The object is not in collection set. If we're a root scanning 4853 // closure during an initial mark pause (i.e. do_mark_object will 4854 // be true) then attempt to mark the object. 4855 if (do_mark_object) { 4856 mark_object(obj); 4857 } 4858 } 4859 4860 if (barrier == G1BarrierEvac) { 4861 _par_scan_state->update_rs(_from, p, _worker_id); 4862 } 4863 } 4864 4865 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p); 4866 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p); 4867 4868 class G1ParEvacuateFollowersClosure : public VoidClosure { 4869 protected: 4870 G1CollectedHeap* _g1h; 4871 G1ParScanThreadState* _par_scan_state; 4872 RefToScanQueueSet* _queues; 4873 ParallelTaskTerminator* _terminator; 4874 4875 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 4876 RefToScanQueueSet* queues() { return _queues; } 4877 ParallelTaskTerminator* terminator() { return _terminator; } 4878 4879 public: 4880 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 4881 G1ParScanThreadState* par_scan_state, 4882 RefToScanQueueSet* queues, 4883 ParallelTaskTerminator* terminator) 4884 : _g1h(g1h), _par_scan_state(par_scan_state), 4885 _queues(queues), _terminator(terminator) {} 4886 4887 void do_void(); 4888 4889 private: 4890 inline bool offer_termination(); 4891 }; 4892 4893 bool G1ParEvacuateFollowersClosure::offer_termination() { 4894 G1ParScanThreadState* const pss = par_scan_state(); 4895 pss->start_term_time(); 4896 const bool res = terminator()->offer_termination(); 4897 pss->end_term_time(); 4898 return res; 4899 } 4900 4901 void G1ParEvacuateFollowersClosure::do_void() { 4902 StarTask stolen_task; 4903 G1ParScanThreadState* const pss = par_scan_state(); 4904 pss->trim_queue(); 4905 4906 do { 4907 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) { 4908 assert(pss->verify_task(stolen_task), "sanity"); 4909 if (stolen_task.is_narrow()) { 4910 pss->deal_with_reference((narrowOop*) stolen_task); 4911 } else { 4912 pss->deal_with_reference((oop*) stolen_task); 4913 } 4914 4915 // We've just processed a reference and we might have made 4916 // available new entries on the queues. So we have to make sure 4917 // we drain the queues as necessary. 4918 pss->trim_queue(); 4919 } 4920 } while (!offer_termination()); 4921 } 4922 4923 class G1KlassScanClosure : public KlassClosure { 4924 G1ParCopyHelper* _closure; 4925 bool _process_only_dirty; 4926 int _count; 4927 public: 4928 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) 4929 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} 4930 void do_klass(Klass* klass) { 4931 // If the klass has not been dirtied we know that there's 4932 // no references into the young gen and we can skip it. 4933 if (!_process_only_dirty || klass->has_modified_oops()) { 4934 // Clean the klass since we're going to scavenge all the metadata. 4935 klass->clear_modified_oops(); 4936 4937 // Tell the closure that this klass is the Klass to scavenge 4938 // and is the one to dirty if oops are left pointing into the young gen. 4939 _closure->set_scanned_klass(klass); 4940 4941 klass->oops_do(_closure); 4942 4943 _closure->set_scanned_klass(NULL); 4944 } 4945 _count++; 4946 } 4947 }; 4948 4949 class G1ParTask : public AbstractGangTask { 4950 protected: 4951 G1CollectedHeap* _g1h; 4952 RefToScanQueueSet *_queues; 4953 ParallelTaskTerminator _terminator; 4954 uint _n_workers; 4955 4956 Mutex _stats_lock; 4957 Mutex* stats_lock() { return &_stats_lock; } 4958 4959 size_t getNCards() { 4960 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1) 4961 / G1BlockOffsetSharedArray::N_bytes; 4962 } 4963 4964 public: 4965 G1ParTask(G1CollectedHeap* g1h, 4966 RefToScanQueueSet *task_queues) 4967 : AbstractGangTask("G1 collection"), 4968 _g1h(g1h), 4969 _queues(task_queues), 4970 _terminator(0, _queues), 4971 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) 4972 {} 4973 4974 RefToScanQueueSet* queues() { return _queues; } 4975 4976 RefToScanQueue *work_queue(int i) { 4977 return queues()->queue(i); 4978 } 4979 4980 ParallelTaskTerminator* terminator() { return &_terminator; } 4981 4982 virtual void set_for_termination(int active_workers) { 4983 // This task calls set_n_termination() in par_non_clean_card_iterate_work() 4984 // in the young space (_par_seq_tasks) in the G1 heap 4985 // for SequentialSubTasksDone. 4986 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap 4987 // both of which need setting by set_n_termination(). 4988 _g1h->SharedHeap::set_n_termination(active_workers); 4989 _g1h->set_n_termination(active_workers); 4990 terminator()->reset_for_reuse(active_workers); 4991 _n_workers = active_workers; 4992 } 4993 4994 void work(uint worker_id) { 4995 if (worker_id >= _n_workers) return; // no work needed this round 4996 4997 double start_time_ms = os::elapsedTime() * 1000.0; 4998 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms); 4999 5000 { 5001 ResourceMark rm; 5002 HandleMark hm; 5003 5004 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 5005 5006 G1ParScanThreadState pss(_g1h, worker_id, rp); 5007 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); 5008 5009 pss.set_evac_failure_closure(&evac_failure_cl); 5010 5011 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp); 5012 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp); 5013 5014 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp); 5015 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp); 5016 5017 bool only_young = _g1h->g1_policy()->gcs_are_young(); 5018 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false); 5019 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young); 5020 5021 OopClosure* scan_root_cl = &only_scan_root_cl; 5022 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s; 5023 5024 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5025 // We also need to mark copied objects. 5026 scan_root_cl = &scan_mark_root_cl; 5027 scan_klasses_cl = &scan_mark_klasses_cl_s; 5028 } 5029 5030 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); 5031 5032 // Don't scan the scavengable methods in the code cache as part 5033 // of strong root scanning. The code roots that point into a 5034 // region in the collection set are scanned when we scan the 5035 // region's RSet. 5036 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings; 5037 5038 pss.start_strong_roots(); 5039 _g1h->g1_process_strong_roots(/* is scavenging */ true, 5040 SharedHeap::ScanningOption(so), 5041 scan_root_cl, 5042 &push_heap_rs_cl, 5043 scan_klasses_cl, 5044 worker_id); 5045 pss.end_strong_roots(); 5046 5047 { 5048 double start = os::elapsedTime(); 5049 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); 5050 evac.do_void(); 5051 double elapsed_ms = (os::elapsedTime()-start)*1000.0; 5052 double term_ms = pss.term_time()*1000.0; 5053 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms); 5054 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts()); 5055 } 5056 _g1h->g1_policy()->record_thread_age_table(pss.age_table()); 5057 _g1h->update_surviving_young_words(pss.surviving_young_words()+1); 5058 5059 if (ParallelGCVerbose) { 5060 MutexLocker x(stats_lock()); 5061 pss.print_termination_stats(worker_id); 5062 } 5063 5064 assert(pss.refs()->is_empty(), "should be empty"); 5065 5066 // Close the inner scope so that the ResourceMark and HandleMark 5067 // destructors are executed here and are included as part of the 5068 // "GC Worker Time". 5069 } 5070 5071 double end_time_ms = os::elapsedTime() * 1000.0; 5072 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms); 5073 } 5074 }; 5075 5076 // *** Common G1 Evacuation Stuff 5077 5078 // This method is run in a GC worker. 5079 5080 void 5081 G1CollectedHeap:: 5082 g1_process_strong_roots(bool is_scavenging, 5083 ScanningOption so, 5084 OopClosure* scan_non_heap_roots, 5085 OopsInHeapRegionClosure* scan_rs, 5086 G1KlassScanClosure* scan_klasses, 5087 uint worker_i) { 5088 5089 // First scan the strong roots 5090 double ext_roots_start = os::elapsedTime(); 5091 double closure_app_time_sec = 0.0; 5092 5093 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots); 5094 5095 process_strong_roots(false, // no scoping; this is parallel code 5096 so, 5097 &buf_scan_non_heap_roots, 5098 scan_klasses 5099 ); 5100 5101 // Now the CM ref_processor roots. 5102 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) { 5103 // We need to treat the discovered reference lists of the 5104 // concurrent mark ref processor as roots and keep entries 5105 // (which are added by the marking threads) on them live 5106 // until they can be processed at the end of marking. 5107 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots); 5108 } 5109 5110 // Finish up any enqueued closure apps (attributed as object copy time). 5111 buf_scan_non_heap_roots.done(); 5112 5113 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds(); 5114 5115 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0); 5116 5117 double ext_root_time_ms = 5118 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0; 5119 5120 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms); 5121 5122 // During conc marking we have to filter the per-thread SATB buffers 5123 // to make sure we remove any oops into the CSet (which will show up 5124 // as implicitly live). 5125 double satb_filtering_ms = 0.0; 5126 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) { 5127 if (mark_in_progress()) { 5128 double satb_filter_start = os::elapsedTime(); 5129 5130 JavaThread::satb_mark_queue_set().filter_thread_buffers(); 5131 5132 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0; 5133 } 5134 } 5135 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms); 5136 5137 // If this is an initial mark pause, and we're not scanning 5138 // the entire code cache, we need to mark the oops in the 5139 // strong code root lists for the regions that are not in 5140 // the collection set. 5141 // Note all threads participate in this set of root tasks. 5142 double mark_strong_code_roots_ms = 0.0; 5143 if (g1_policy()->during_initial_mark_pause() && !(so & SO_AllCodeCache)) { 5144 double mark_strong_roots_start = os::elapsedTime(); 5145 mark_strong_code_roots(worker_i); 5146 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0; 5147 } 5148 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms); 5149 5150 // Now scan the complement of the collection set. 5151 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */); 5152 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i); 5153 5154 _process_strong_tasks->all_tasks_completed(); 5155 } 5156 5157 class G1StringSymbolTableUnlinkTask : public AbstractGangTask { 5158 private: 5159 BoolObjectClosure* _is_alive; 5160 int _initial_string_table_size; 5161 int _initial_symbol_table_size; 5162 5163 bool _process_strings; 5164 int _strings_processed; 5165 int _strings_removed; 5166 5167 bool _process_symbols; 5168 int _symbols_processed; 5169 int _symbols_removed; 5170 5171 bool _do_in_parallel; 5172 public: 5173 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : 5174 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive), 5175 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()), 5176 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 5177 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { 5178 5179 _initial_string_table_size = StringTable::the_table()->table_size(); 5180 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 5181 if (process_strings) { 5182 StringTable::clear_parallel_claimed_index(); 5183 } 5184 if (process_symbols) { 5185 SymbolTable::clear_parallel_claimed_index(); 5186 } 5187 } 5188 5189 ~G1StringSymbolTableUnlinkTask() { 5190 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size, 5191 err_msg("claim value %d after unlink less than initial string table size %d", 5192 StringTable::parallel_claimed_index(), _initial_string_table_size)); 5193 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 5194 err_msg("claim value %d after unlink less than initial symbol table size %d", 5195 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); 5196 } 5197 5198 void work(uint worker_id) { 5199 if (_do_in_parallel) { 5200 int strings_processed = 0; 5201 int strings_removed = 0; 5202 int symbols_processed = 0; 5203 int symbols_removed = 0; 5204 if (_process_strings) { 5205 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 5206 Atomic::add(strings_processed, &_strings_processed); 5207 Atomic::add(strings_removed, &_strings_removed); 5208 } 5209 if (_process_symbols) { 5210 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 5211 Atomic::add(symbols_processed, &_symbols_processed); 5212 Atomic::add(symbols_removed, &_symbols_removed); 5213 } 5214 } else { 5215 if (_process_strings) { 5216 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed); 5217 } 5218 if (_process_symbols) { 5219 SymbolTable::unlink(&_symbols_processed, &_symbols_removed); 5220 } 5221 } 5222 } 5223 5224 size_t strings_processed() const { return (size_t)_strings_processed; } 5225 size_t strings_removed() const { return (size_t)_strings_removed; } 5226 5227 size_t symbols_processed() const { return (size_t)_symbols_processed; } 5228 size_t symbols_removed() const { return (size_t)_symbols_removed; } 5229 }; 5230 5231 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, 5232 bool process_strings, bool process_symbols) { 5233 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5234 _g1h->workers()->active_workers() : 1); 5235 5236 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); 5237 if (G1CollectedHeap::use_parallel_gc_threads()) { 5238 set_par_threads(n_workers); 5239 workers()->run_task(&g1_unlink_task); 5240 set_par_threads(0); 5241 } else { 5242 g1_unlink_task.work(0); 5243 } 5244 if (G1TraceStringSymbolTableScrubbing) { 5245 gclog_or_tty->print_cr("Cleaned string and symbol table, " 5246 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " 5247 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", 5248 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(), 5249 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed()); 5250 } 5251 5252 if (G1StringDedup::is_enabled()) { 5253 G1StringDedup::unlink(is_alive); 5254 } 5255 } 5256 5257 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure { 5258 private: 5259 size_t _num_processed; 5260 5261 public: 5262 RedirtyLoggedCardTableEntryFastClosure() : CardTableEntryClosure(), _num_processed(0) { } 5263 5264 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 5265 *card_ptr = CardTableModRefBS::dirty_card_val(); 5266 _num_processed++; 5267 return true; 5268 } 5269 5270 size_t num_processed() const { return _num_processed; } 5271 }; 5272 5273 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 5274 private: 5275 DirtyCardQueueSet* _queue; 5276 public: 5277 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } 5278 5279 virtual void work(uint worker_id) { 5280 double start_time = os::elapsedTime(); 5281 5282 RedirtyLoggedCardTableEntryFastClosure cl; 5283 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) { 5284 _queue->par_apply_closure_to_all_completed_buffers(&cl); 5285 } else { 5286 _queue->apply_closure_to_all_completed_buffers(&cl); 5287 } 5288 5289 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 5290 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0); 5291 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed()); 5292 } 5293 }; 5294 5295 void G1CollectedHeap::redirty_logged_cards() { 5296 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates."); 5297 double redirty_logged_cards_start = os::elapsedTime(); 5298 5299 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ? 5300 _g1h->workers()->active_workers() : 1); 5301 5302 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); 5303 dirty_card_queue_set().reset_for_par_iteration(); 5304 if (use_parallel_gc_threads()) { 5305 set_par_threads(n_workers); 5306 workers()->run_task(&redirty_task); 5307 set_par_threads(0); 5308 } else { 5309 redirty_task.work(0); 5310 } 5311 5312 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); 5313 dcq.merge_bufferlists(&dirty_card_queue_set()); 5314 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 5315 5316 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 5317 } 5318 5319 // Weak Reference Processing support 5320 5321 // An always "is_alive" closure that is used to preserve referents. 5322 // If the object is non-null then it's alive. Used in the preservation 5323 // of referent objects that are pointed to by reference objects 5324 // discovered by the CM ref processor. 5325 class G1AlwaysAliveClosure: public BoolObjectClosure { 5326 G1CollectedHeap* _g1; 5327 public: 5328 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5329 bool do_object_b(oop p) { 5330 if (p != NULL) { 5331 return true; 5332 } 5333 return false; 5334 } 5335 }; 5336 5337 bool G1STWIsAliveClosure::do_object_b(oop p) { 5338 // An object is reachable if it is outside the collection set, 5339 // or is inside and copied. 5340 return !_g1->obj_in_cs(p) || p->is_forwarded(); 5341 } 5342 5343 // Non Copying Keep Alive closure 5344 class G1KeepAliveClosure: public OopClosure { 5345 G1CollectedHeap* _g1; 5346 public: 5347 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 5348 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 5349 void do_oop( oop* p) { 5350 oop obj = *p; 5351 5352 if (_g1->obj_in_cs(obj)) { 5353 assert( obj->is_forwarded(), "invariant" ); 5354 *p = obj->forwardee(); 5355 } 5356 } 5357 }; 5358 5359 // Copying Keep Alive closure - can be called from both 5360 // serial and parallel code as long as different worker 5361 // threads utilize different G1ParScanThreadState instances 5362 // and different queues. 5363 5364 class G1CopyingKeepAliveClosure: public OopClosure { 5365 G1CollectedHeap* _g1h; 5366 OopClosure* _copy_non_heap_obj_cl; 5367 OopsInHeapRegionClosure* _copy_metadata_obj_cl; 5368 G1ParScanThreadState* _par_scan_state; 5369 5370 public: 5371 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 5372 OopClosure* non_heap_obj_cl, 5373 OopsInHeapRegionClosure* metadata_obj_cl, 5374 G1ParScanThreadState* pss): 5375 _g1h(g1h), 5376 _copy_non_heap_obj_cl(non_heap_obj_cl), 5377 _copy_metadata_obj_cl(metadata_obj_cl), 5378 _par_scan_state(pss) 5379 {} 5380 5381 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 5382 virtual void do_oop( oop* p) { do_oop_work(p); } 5383 5384 template <class T> void do_oop_work(T* p) { 5385 oop obj = oopDesc::load_decode_heap_oop(p); 5386 5387 if (_g1h->obj_in_cs(obj)) { 5388 // If the referent object has been forwarded (either copied 5389 // to a new location or to itself in the event of an 5390 // evacuation failure) then we need to update the reference 5391 // field and, if both reference and referent are in the G1 5392 // heap, update the RSet for the referent. 5393 // 5394 // If the referent has not been forwarded then we have to keep 5395 // it alive by policy. Therefore we have copy the referent. 5396 // 5397 // If the reference field is in the G1 heap then we can push 5398 // on the PSS queue. When the queue is drained (after each 5399 // phase of reference processing) the object and it's followers 5400 // will be copied, the reference field set to point to the 5401 // new location, and the RSet updated. Otherwise we need to 5402 // use the the non-heap or metadata closures directly to copy 5403 // the referent object and update the pointer, while avoiding 5404 // updating the RSet. 5405 5406 if (_g1h->is_in_g1_reserved(p)) { 5407 _par_scan_state->push_on_queue(p); 5408 } else { 5409 assert(!ClassLoaderDataGraph::contains((address)p), 5410 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) " 5411 PTR_FORMAT, p)); 5412 _copy_non_heap_obj_cl->do_oop(p); 5413 } 5414 } 5415 } 5416 }; 5417 5418 // Serial drain queue closure. Called as the 'complete_gc' 5419 // closure for each discovered list in some of the 5420 // reference processing phases. 5421 5422 class G1STWDrainQueueClosure: public VoidClosure { 5423 protected: 5424 G1CollectedHeap* _g1h; 5425 G1ParScanThreadState* _par_scan_state; 5426 5427 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 5428 5429 public: 5430 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 5431 _g1h(g1h), 5432 _par_scan_state(pss) 5433 { } 5434 5435 void do_void() { 5436 G1ParScanThreadState* const pss = par_scan_state(); 5437 pss->trim_queue(); 5438 } 5439 }; 5440 5441 // Parallel Reference Processing closures 5442 5443 // Implementation of AbstractRefProcTaskExecutor for parallel reference 5444 // processing during G1 evacuation pauses. 5445 5446 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 5447 private: 5448 G1CollectedHeap* _g1h; 5449 RefToScanQueueSet* _queues; 5450 FlexibleWorkGang* _workers; 5451 int _active_workers; 5452 5453 public: 5454 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 5455 FlexibleWorkGang* workers, 5456 RefToScanQueueSet *task_queues, 5457 int n_workers) : 5458 _g1h(g1h), 5459 _queues(task_queues), 5460 _workers(workers), 5461 _active_workers(n_workers) 5462 { 5463 assert(n_workers > 0, "shouldn't call this otherwise"); 5464 } 5465 5466 // Executes the given task using concurrent marking worker threads. 5467 virtual void execute(ProcessTask& task); 5468 virtual void execute(EnqueueTask& task); 5469 }; 5470 5471 // Gang task for possibly parallel reference processing 5472 5473 class G1STWRefProcTaskProxy: public AbstractGangTask { 5474 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 5475 ProcessTask& _proc_task; 5476 G1CollectedHeap* _g1h; 5477 RefToScanQueueSet *_task_queues; 5478 ParallelTaskTerminator* _terminator; 5479 5480 public: 5481 G1STWRefProcTaskProxy(ProcessTask& proc_task, 5482 G1CollectedHeap* g1h, 5483 RefToScanQueueSet *task_queues, 5484 ParallelTaskTerminator* terminator) : 5485 AbstractGangTask("Process reference objects in parallel"), 5486 _proc_task(proc_task), 5487 _g1h(g1h), 5488 _task_queues(task_queues), 5489 _terminator(terminator) 5490 {} 5491 5492 virtual void work(uint worker_id) { 5493 // The reference processing task executed by a single worker. 5494 ResourceMark rm; 5495 HandleMark hm; 5496 5497 G1STWIsAliveClosure is_alive(_g1h); 5498 5499 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5500 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5501 5502 pss.set_evac_failure_closure(&evac_failure_cl); 5503 5504 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5505 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL); 5506 5507 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5508 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL); 5509 5510 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5511 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl; 5512 5513 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5514 // We also need to mark copied objects. 5515 copy_non_heap_cl = ©_mark_non_heap_cl; 5516 copy_metadata_cl = ©_mark_metadata_cl; 5517 } 5518 5519 // Keep alive closure. 5520 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss); 5521 5522 // Complete GC closure 5523 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); 5524 5525 // Call the reference processing task's work routine. 5526 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 5527 5528 // Note we cannot assert that the refs array is empty here as not all 5529 // of the processing tasks (specifically phase2 - pp2_work) execute 5530 // the complete_gc closure (which ordinarily would drain the queue) so 5531 // the queue may not be empty. 5532 } 5533 }; 5534 5535 // Driver routine for parallel reference processing. 5536 // Creates an instance of the ref processing gang 5537 // task and has the worker threads execute it. 5538 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 5539 assert(_workers != NULL, "Need parallel worker threads."); 5540 5541 ParallelTaskTerminator terminator(_active_workers, _queues); 5542 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); 5543 5544 _g1h->set_par_threads(_active_workers); 5545 _workers->run_task(&proc_task_proxy); 5546 _g1h->set_par_threads(0); 5547 } 5548 5549 // Gang task for parallel reference enqueueing. 5550 5551 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 5552 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 5553 EnqueueTask& _enq_task; 5554 5555 public: 5556 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 5557 AbstractGangTask("Enqueue reference objects in parallel"), 5558 _enq_task(enq_task) 5559 { } 5560 5561 virtual void work(uint worker_id) { 5562 _enq_task.work(worker_id); 5563 } 5564 }; 5565 5566 // Driver routine for parallel reference enqueueing. 5567 // Creates an instance of the ref enqueueing gang 5568 // task and has the worker threads execute it. 5569 5570 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 5571 assert(_workers != NULL, "Need parallel worker threads."); 5572 5573 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 5574 5575 _g1h->set_par_threads(_active_workers); 5576 _workers->run_task(&enq_task_proxy); 5577 _g1h->set_par_threads(0); 5578 } 5579 5580 // End of weak reference support closures 5581 5582 // Abstract task used to preserve (i.e. copy) any referent objects 5583 // that are in the collection set and are pointed to by reference 5584 // objects discovered by the CM ref processor. 5585 5586 class G1ParPreserveCMReferentsTask: public AbstractGangTask { 5587 protected: 5588 G1CollectedHeap* _g1h; 5589 RefToScanQueueSet *_queues; 5590 ParallelTaskTerminator _terminator; 5591 uint _n_workers; 5592 5593 public: 5594 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) : 5595 AbstractGangTask("ParPreserveCMReferents"), 5596 _g1h(g1h), 5597 _queues(task_queues), 5598 _terminator(workers, _queues), 5599 _n_workers(workers) 5600 { } 5601 5602 void work(uint worker_id) { 5603 ResourceMark rm; 5604 HandleMark hm; 5605 5606 G1ParScanThreadState pss(_g1h, worker_id, NULL); 5607 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); 5608 5609 pss.set_evac_failure_closure(&evac_failure_cl); 5610 5611 assert(pss.refs()->is_empty(), "both queue and overflow should be empty"); 5612 5613 5614 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); 5615 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL); 5616 5617 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); 5618 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL); 5619 5620 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5621 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl; 5622 5623 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5624 // We also need to mark copied objects. 5625 copy_non_heap_cl = ©_mark_non_heap_cl; 5626 copy_metadata_cl = ©_mark_metadata_cl; 5627 } 5628 5629 // Is alive closure 5630 G1AlwaysAliveClosure always_alive(_g1h); 5631 5632 // Copying keep alive closure. Applied to referent objects that need 5633 // to be copied. 5634 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss); 5635 5636 ReferenceProcessor* rp = _g1h->ref_processor_cm(); 5637 5638 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); 5639 uint stride = MIN2(MAX2(_n_workers, 1U), limit); 5640 5641 // limit is set using max_num_q() - which was set using ParallelGCThreads. 5642 // So this must be true - but assert just in case someone decides to 5643 // change the worker ids. 5644 assert(0 <= worker_id && worker_id < limit, "sanity"); 5645 assert(!rp->discovery_is_atomic(), "check this code"); 5646 5647 // Select discovered lists [i, i+stride, i+2*stride,...,limit) 5648 for (uint idx = worker_id; idx < limit; idx += stride) { 5649 DiscoveredList& ref_list = rp->discovered_refs()[idx]; 5650 5651 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); 5652 while (iter.has_next()) { 5653 // Since discovery is not atomic for the CM ref processor, we 5654 // can see some null referent objects. 5655 iter.load_ptrs(DEBUG_ONLY(true)); 5656 oop ref = iter.obj(); 5657 5658 // This will filter nulls. 5659 if (iter.is_referent_alive()) { 5660 iter.make_referent_alive(); 5661 } 5662 iter.move_to_next(); 5663 } 5664 } 5665 5666 // Drain the queue - which may cause stealing 5667 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); 5668 drain_queue.do_void(); 5669 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure 5670 assert(pss.refs()->is_empty(), "should be"); 5671 } 5672 }; 5673 5674 // Weak Reference processing during an evacuation pause (part 1). 5675 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { 5676 double ref_proc_start = os::elapsedTime(); 5677 5678 ReferenceProcessor* rp = _ref_processor_stw; 5679 assert(rp->discovery_enabled(), "should have been enabled"); 5680 5681 // Any reference objects, in the collection set, that were 'discovered' 5682 // by the CM ref processor should have already been copied (either by 5683 // applying the external root copy closure to the discovered lists, or 5684 // by following an RSet entry). 5685 // 5686 // But some of the referents, that are in the collection set, that these 5687 // reference objects point to may not have been copied: the STW ref 5688 // processor would have seen that the reference object had already 5689 // been 'discovered' and would have skipped discovering the reference, 5690 // but would not have treated the reference object as a regular oop. 5691 // As a result the copy closure would not have been applied to the 5692 // referent object. 5693 // 5694 // We need to explicitly copy these referent objects - the references 5695 // will be processed at the end of remarking. 5696 // 5697 // We also need to do this copying before we process the reference 5698 // objects discovered by the STW ref processor in case one of these 5699 // referents points to another object which is also referenced by an 5700 // object discovered by the STW ref processor. 5701 5702 assert(!G1CollectedHeap::use_parallel_gc_threads() || 5703 no_of_gc_workers == workers()->active_workers(), 5704 "Need to reset active GC workers"); 5705 5706 set_par_threads(no_of_gc_workers); 5707 G1ParPreserveCMReferentsTask keep_cm_referents(this, 5708 no_of_gc_workers, 5709 _task_queues); 5710 5711 if (G1CollectedHeap::use_parallel_gc_threads()) { 5712 workers()->run_task(&keep_cm_referents); 5713 } else { 5714 keep_cm_referents.work(0); 5715 } 5716 5717 set_par_threads(0); 5718 5719 // Closure to test whether a referent is alive. 5720 G1STWIsAliveClosure is_alive(this); 5721 5722 // Even when parallel reference processing is enabled, the processing 5723 // of JNI refs is serial and performed serially by the current thread 5724 // rather than by a worker. The following PSS will be used for processing 5725 // JNI refs. 5726 5727 // Use only a single queue for this PSS. 5728 G1ParScanThreadState pss(this, 0, NULL); 5729 5730 // We do not embed a reference processor in the copying/scanning 5731 // closures while we're actually processing the discovered 5732 // reference objects. 5733 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); 5734 5735 pss.set_evac_failure_closure(&evac_failure_cl); 5736 5737 assert(pss.refs()->is_empty(), "pre-condition"); 5738 5739 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); 5740 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL); 5741 5742 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); 5743 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL); 5744 5745 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; 5746 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl; 5747 5748 if (_g1h->g1_policy()->during_initial_mark_pause()) { 5749 // We also need to mark copied objects. 5750 copy_non_heap_cl = ©_mark_non_heap_cl; 5751 copy_metadata_cl = ©_mark_metadata_cl; 5752 } 5753 5754 // Keep alive closure. 5755 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss); 5756 5757 // Serial Complete GC closure 5758 G1STWDrainQueueClosure drain_queue(this, &pss); 5759 5760 // Setup the soft refs policy... 5761 rp->setup_policy(false); 5762 5763 ReferenceProcessorStats stats; 5764 if (!rp->processing_is_mt()) { 5765 // Serial reference processing... 5766 stats = rp->process_discovered_references(&is_alive, 5767 &keep_alive, 5768 &drain_queue, 5769 NULL, 5770 _gc_timer_stw); 5771 } else { 5772 // Parallel reference processing 5773 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5774 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5775 5776 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5777 stats = rp->process_discovered_references(&is_alive, 5778 &keep_alive, 5779 &drain_queue, 5780 &par_task_executor, 5781 _gc_timer_stw); 5782 } 5783 5784 _gc_tracer_stw->report_gc_reference_stats(stats); 5785 5786 // We have completed copying any necessary live referent objects. 5787 assert(pss.refs()->is_empty(), "both queue and overflow should be empty"); 5788 5789 double ref_proc_time = os::elapsedTime() - ref_proc_start; 5790 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 5791 } 5792 5793 // Weak Reference processing during an evacuation pause (part 2). 5794 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { 5795 double ref_enq_start = os::elapsedTime(); 5796 5797 ReferenceProcessor* rp = _ref_processor_stw; 5798 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 5799 5800 // Now enqueue any remaining on the discovered lists on to 5801 // the pending list. 5802 if (!rp->processing_is_mt()) { 5803 // Serial reference processing... 5804 rp->enqueue_discovered_references(); 5805 } else { 5806 // Parallel reference enqueueing 5807 5808 assert(no_of_gc_workers == workers()->active_workers(), 5809 "Need to reset active workers"); 5810 assert(rp->num_q() == no_of_gc_workers, "sanity"); 5811 assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); 5812 5813 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); 5814 rp->enqueue_discovered_references(&par_task_executor); 5815 } 5816 5817 rp->verify_no_references_recorded(); 5818 assert(!rp->discovery_enabled(), "should have been disabled"); 5819 5820 // FIXME 5821 // CM's reference processing also cleans up the string and symbol tables. 5822 // Should we do that here also? We could, but it is a serial operation 5823 // and could significantly increase the pause time. 5824 5825 double ref_enq_time = os::elapsedTime() - ref_enq_start; 5826 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 5827 } 5828 5829 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { 5830 _expand_heap_after_alloc_failure = true; 5831 _evacuation_failed = false; 5832 5833 // Should G1EvacuationFailureALot be in effect for this GC? 5834 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 5835 5836 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 5837 5838 // Disable the hot card cache. 5839 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); 5840 hot_card_cache->reset_hot_cache_claimed_index(); 5841 hot_card_cache->set_use_cache(false); 5842 5843 uint n_workers; 5844 if (G1CollectedHeap::use_parallel_gc_threads()) { 5845 n_workers = 5846 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 5847 workers()->active_workers(), 5848 Threads::number_of_non_daemon_threads()); 5849 assert(UseDynamicNumberOfGCThreads || 5850 n_workers == workers()->total_workers(), 5851 "If not dynamic should be using all the workers"); 5852 workers()->set_active_workers(n_workers); 5853 set_par_threads(n_workers); 5854 } else { 5855 assert(n_par_threads() == 0, 5856 "Should be the original non-parallel value"); 5857 n_workers = 1; 5858 } 5859 5860 G1ParTask g1_par_task(this, _task_queues); 5861 5862 init_for_evac_failure(NULL); 5863 5864 rem_set()->prepare_for_younger_refs_iterate(true); 5865 5866 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 5867 double start_par_time_sec = os::elapsedTime(); 5868 double end_par_time_sec; 5869 5870 { 5871 StrongRootsScope srs(this); 5872 5873 if (G1CollectedHeap::use_parallel_gc_threads()) { 5874 // The individual threads will set their evac-failure closures. 5875 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr(); 5876 // These tasks use ShareHeap::_process_strong_tasks 5877 assert(UseDynamicNumberOfGCThreads || 5878 workers()->active_workers() == workers()->total_workers(), 5879 "If not dynamic should be using all the workers"); 5880 workers()->run_task(&g1_par_task); 5881 } else { 5882 g1_par_task.set_for_termination(n_workers); 5883 g1_par_task.work(0); 5884 } 5885 end_par_time_sec = os::elapsedTime(); 5886 5887 // Closing the inner scope will execute the destructor 5888 // for the StrongRootsScope object. We record the current 5889 // elapsed time before closing the scope so that time 5890 // taken for the SRS destructor is NOT included in the 5891 // reported parallel time. 5892 } 5893 5894 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 5895 g1_policy()->phase_times()->record_par_time(par_time_ms); 5896 5897 double code_root_fixup_time_ms = 5898 (os::elapsedTime() - end_par_time_sec) * 1000.0; 5899 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms); 5900 5901 set_par_threads(0); 5902 5903 // Process any discovered reference objects - we have 5904 // to do this _before_ we retire the GC alloc regions 5905 // as we may have to copy some 'reachable' referent 5906 // objects (and their reachable sub-graphs) that were 5907 // not copied during the pause. 5908 process_discovered_references(n_workers); 5909 5910 // Weak root processing. 5911 { 5912 G1STWIsAliveClosure is_alive(this); 5913 G1KeepAliveClosure keep_alive(this); 5914 JNIHandles::weak_oops_do(&is_alive, &keep_alive); 5915 if (G1StringDedup::is_enabled()) { 5916 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive); 5917 } 5918 } 5919 5920 release_gc_alloc_regions(n_workers, evacuation_info); 5921 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 5922 5923 // Reset and re-enable the hot card cache. 5924 // Note the counts for the cards in the regions in the 5925 // collection set are reset when the collection set is freed. 5926 hot_card_cache->reset_hot_cache(); 5927 hot_card_cache->set_use_cache(true); 5928 5929 // Migrate the strong code roots attached to each region in 5930 // the collection set. Ideally we would like to do this 5931 // after we have finished the scanning/evacuation of the 5932 // strong code roots for a particular heap region. 5933 migrate_strong_code_roots(); 5934 5935 purge_code_root_memory(); 5936 5937 if (g1_policy()->during_initial_mark_pause()) { 5938 // Reset the claim values set during marking the strong code roots 5939 reset_heap_region_claim_values(); 5940 } 5941 5942 finalize_for_evac_failure(); 5943 5944 if (evacuation_failed()) { 5945 remove_self_forwarding_pointers(); 5946 5947 // Reset the G1EvacuationFailureALot counters and flags 5948 // Note: the values are reset only when an actual 5949 // evacuation failure occurs. 5950 NOT_PRODUCT(reset_evacuation_should_fail();) 5951 } 5952 5953 // Enqueue any remaining references remaining on the STW 5954 // reference processor's discovered lists. We need to do 5955 // this after the card table is cleaned (and verified) as 5956 // the act of enqueueing entries on to the pending list 5957 // will log these updates (and dirty their associated 5958 // cards). We need these updates logged to update any 5959 // RSets. 5960 enqueue_discovered_references(n_workers); 5961 5962 if (G1DeferredRSUpdate) { 5963 redirty_logged_cards(); 5964 } 5965 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 5966 } 5967 5968 void G1CollectedHeap::free_region(HeapRegion* hr, 5969 FreeRegionList* free_list, 5970 bool par, 5971 bool locked) { 5972 assert(!hr->isHumongous(), "this is only for non-humongous regions"); 5973 assert(!hr->is_empty(), "the region should not be empty"); 5974 assert(free_list != NULL, "pre-condition"); 5975 5976 // Clear the card counts for this region. 5977 // Note: we only need to do this if the region is not young 5978 // (since we don't refine cards in young regions). 5979 if (!hr->is_young()) { 5980 _cg1r->hot_card_cache()->reset_card_counts(hr); 5981 } 5982 hr->hr_clear(par, true /* clear_space */, locked /* locked */); 5983 free_list->add_ordered(hr); 5984 } 5985 5986 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 5987 FreeRegionList* free_list, 5988 bool par) { 5989 assert(hr->startsHumongous(), "this is only for starts humongous regions"); 5990 assert(free_list != NULL, "pre-condition"); 5991 5992 size_t hr_capacity = hr->capacity(); 5993 // We need to read this before we make the region non-humongous, 5994 // otherwise the information will be gone. 5995 uint last_index = hr->last_hc_index(); 5996 hr->set_notHumongous(); 5997 free_region(hr, free_list, par); 5998 5999 uint i = hr->hrs_index() + 1; 6000 while (i < last_index) { 6001 HeapRegion* curr_hr = region_at(i); 6002 assert(curr_hr->continuesHumongous(), "invariant"); 6003 curr_hr->set_notHumongous(); 6004 free_region(curr_hr, free_list, par); 6005 i += 1; 6006 } 6007 } 6008 6009 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, 6010 const HeapRegionSetCount& humongous_regions_removed) { 6011 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { 6012 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 6013 _old_set.bulk_remove(old_regions_removed); 6014 _humongous_set.bulk_remove(humongous_regions_removed); 6015 } 6016 6017 } 6018 6019 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 6020 assert(list != NULL, "list can't be null"); 6021 if (!list->is_empty()) { 6022 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 6023 _free_list.add_ordered(list); 6024 } 6025 } 6026 6027 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 6028 assert(_summary_bytes_used >= bytes, 6029 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT, 6030 _summary_bytes_used, bytes)); 6031 _summary_bytes_used -= bytes; 6032 } 6033 6034 class G1ParCleanupCTTask : public AbstractGangTask { 6035 G1SATBCardTableModRefBS* _ct_bs; 6036 G1CollectedHeap* _g1h; 6037 HeapRegion* volatile _su_head; 6038 public: 6039 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, 6040 G1CollectedHeap* g1h) : 6041 AbstractGangTask("G1 Par Cleanup CT Task"), 6042 _ct_bs(ct_bs), _g1h(g1h) { } 6043 6044 void work(uint worker_id) { 6045 HeapRegion* r; 6046 while (r = _g1h->pop_dirty_cards_region()) { 6047 clear_cards(r); 6048 } 6049 } 6050 6051 void clear_cards(HeapRegion* r) { 6052 // Cards of the survivors should have already been dirtied. 6053 if (!r->is_survivor()) { 6054 _ct_bs->clear(MemRegion(r->bottom(), r->end())); 6055 } 6056 } 6057 }; 6058 6059 #ifndef PRODUCT 6060 class G1VerifyCardTableCleanup: public HeapRegionClosure { 6061 G1CollectedHeap* _g1h; 6062 G1SATBCardTableModRefBS* _ct_bs; 6063 public: 6064 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) 6065 : _g1h(g1h), _ct_bs(ct_bs) { } 6066 virtual bool doHeapRegion(HeapRegion* r) { 6067 if (r->is_survivor()) { 6068 _g1h->verify_dirty_region(r); 6069 } else { 6070 _g1h->verify_not_dirty_region(r); 6071 } 6072 return false; 6073 } 6074 }; 6075 6076 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { 6077 // All of the region should be clean. 6078 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6079 MemRegion mr(hr->bottom(), hr->end()); 6080 ct_bs->verify_not_dirty_region(mr); 6081 } 6082 6083 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { 6084 // We cannot guarantee that [bottom(),end()] is dirty. Threads 6085 // dirty allocated blocks as they allocate them. The thread that 6086 // retires each region and replaces it with a new one will do a 6087 // maximal allocation to fill in [pre_dummy_top(),end()] but will 6088 // not dirty that area (one less thing to have to do while holding 6089 // a lock). So we can only verify that [bottom(),pre_dummy_top()] 6090 // is dirty. 6091 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6092 MemRegion mr(hr->bottom(), hr->pre_dummy_top()); 6093 if (hr->is_young()) { 6094 ct_bs->verify_g1_young_region(mr); 6095 } else { 6096 ct_bs->verify_dirty_region(mr); 6097 } 6098 } 6099 6100 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { 6101 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6102 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { 6103 verify_dirty_region(hr); 6104 } 6105 } 6106 6107 void G1CollectedHeap::verify_dirty_young_regions() { 6108 verify_dirty_young_list(_young_list->first_region()); 6109 } 6110 #endif 6111 6112 void G1CollectedHeap::cleanUpCardTable() { 6113 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); 6114 double start = os::elapsedTime(); 6115 6116 { 6117 // Iterate over the dirty cards region list. 6118 G1ParCleanupCTTask cleanup_task(ct_bs, this); 6119 6120 if (G1CollectedHeap::use_parallel_gc_threads()) { 6121 set_par_threads(); 6122 workers()->run_task(&cleanup_task); 6123 set_par_threads(0); 6124 } else { 6125 while (_dirty_cards_region_list) { 6126 HeapRegion* r = _dirty_cards_region_list; 6127 cleanup_task.clear_cards(r); 6128 _dirty_cards_region_list = r->get_next_dirty_cards_region(); 6129 if (_dirty_cards_region_list == r) { 6130 // The last region. 6131 _dirty_cards_region_list = NULL; 6132 } 6133 r->set_next_dirty_cards_region(NULL); 6134 } 6135 } 6136 #ifndef PRODUCT 6137 if (G1VerifyCTCleanup || VerifyAfterGC) { 6138 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); 6139 heap_region_iterate(&cleanup_verifier); 6140 } 6141 #endif 6142 } 6143 6144 double elapsed = os::elapsedTime() - start; 6145 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); 6146 } 6147 6148 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { 6149 size_t pre_used = 0; 6150 FreeRegionList local_free_list("Local List for CSet Freeing"); 6151 6152 double young_time_ms = 0.0; 6153 double non_young_time_ms = 0.0; 6154 6155 // Since the collection set is a superset of the the young list, 6156 // all we need to do to clear the young list is clear its 6157 // head and length, and unlink any young regions in the code below 6158 _young_list->clear(); 6159 6160 G1CollectorPolicy* policy = g1_policy(); 6161 6162 double start_sec = os::elapsedTime(); 6163 bool non_young = true; 6164 6165 HeapRegion* cur = cs_head; 6166 int age_bound = -1; 6167 size_t rs_lengths = 0; 6168 6169 while (cur != NULL) { 6170 assert(!is_on_master_free_list(cur), "sanity"); 6171 if (non_young) { 6172 if (cur->is_young()) { 6173 double end_sec = os::elapsedTime(); 6174 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6175 non_young_time_ms += elapsed_ms; 6176 6177 start_sec = os::elapsedTime(); 6178 non_young = false; 6179 } 6180 } else { 6181 if (!cur->is_young()) { 6182 double end_sec = os::elapsedTime(); 6183 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6184 young_time_ms += elapsed_ms; 6185 6186 start_sec = os::elapsedTime(); 6187 non_young = true; 6188 } 6189 } 6190 6191 rs_lengths += cur->rem_set()->occupied_locked(); 6192 6193 HeapRegion* next = cur->next_in_collection_set(); 6194 assert(cur->in_collection_set(), "bad CS"); 6195 cur->set_next_in_collection_set(NULL); 6196 cur->set_in_collection_set(false); 6197 6198 if (cur->is_young()) { 6199 int index = cur->young_index_in_cset(); 6200 assert(index != -1, "invariant"); 6201 assert((uint) index < policy->young_cset_region_length(), "invariant"); 6202 size_t words_survived = _surviving_young_words[index]; 6203 cur->record_surv_words_in_group(words_survived); 6204 6205 // At this point the we have 'popped' cur from the collection set 6206 // (linked via next_in_collection_set()) but it is still in the 6207 // young list (linked via next_young_region()). Clear the 6208 // _next_young_region field. 6209 cur->set_next_young_region(NULL); 6210 } else { 6211 int index = cur->young_index_in_cset(); 6212 assert(index == -1, "invariant"); 6213 } 6214 6215 assert( (cur->is_young() && cur->young_index_in_cset() > -1) || 6216 (!cur->is_young() && cur->young_index_in_cset() == -1), 6217 "invariant" ); 6218 6219 if (!cur->evacuation_failed()) { 6220 MemRegion used_mr = cur->used_region(); 6221 6222 // And the region is empty. 6223 assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); 6224 pre_used += cur->used(); 6225 free_region(cur, &local_free_list, false /* par */, true /* locked */); 6226 } else { 6227 cur->uninstall_surv_rate_group(); 6228 if (cur->is_young()) { 6229 cur->set_young_index_in_cset(-1); 6230 } 6231 cur->set_not_young(); 6232 cur->set_evacuation_failed(false); 6233 // The region is now considered to be old. 6234 _old_set.add(cur); 6235 evacuation_info.increment_collectionset_used_after(cur->used()); 6236 } 6237 cur = next; 6238 } 6239 6240 evacuation_info.set_regions_freed(local_free_list.length()); 6241 policy->record_max_rs_lengths(rs_lengths); 6242 policy->cset_regions_freed(); 6243 6244 double end_sec = os::elapsedTime(); 6245 double elapsed_ms = (end_sec - start_sec) * 1000.0; 6246 6247 if (non_young) { 6248 non_young_time_ms += elapsed_ms; 6249 } else { 6250 young_time_ms += elapsed_ms; 6251 } 6252 6253 prepend_to_freelist(&local_free_list); 6254 decrement_summary_bytes(pre_used); 6255 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); 6256 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); 6257 } 6258 6259 // This routine is similar to the above but does not record 6260 // any policy statistics or update free lists; we are abandoning 6261 // the current incremental collection set in preparation of a 6262 // full collection. After the full GC we will start to build up 6263 // the incremental collection set again. 6264 // This is only called when we're doing a full collection 6265 // and is immediately followed by the tearing down of the young list. 6266 6267 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { 6268 HeapRegion* cur = cs_head; 6269 6270 while (cur != NULL) { 6271 HeapRegion* next = cur->next_in_collection_set(); 6272 assert(cur->in_collection_set(), "bad CS"); 6273 cur->set_next_in_collection_set(NULL); 6274 cur->set_in_collection_set(false); 6275 cur->set_young_index_in_cset(-1); 6276 cur = next; 6277 } 6278 } 6279 6280 void G1CollectedHeap::set_free_regions_coming() { 6281 if (G1ConcRegionFreeingVerbose) { 6282 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6283 "setting free regions coming"); 6284 } 6285 6286 assert(!free_regions_coming(), "pre-condition"); 6287 _free_regions_coming = true; 6288 } 6289 6290 void G1CollectedHeap::reset_free_regions_coming() { 6291 assert(free_regions_coming(), "pre-condition"); 6292 6293 { 6294 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6295 _free_regions_coming = false; 6296 SecondaryFreeList_lock->notify_all(); 6297 } 6298 6299 if (G1ConcRegionFreeingVerbose) { 6300 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " 6301 "reset free regions coming"); 6302 } 6303 } 6304 6305 void G1CollectedHeap::wait_while_free_regions_coming() { 6306 // Most of the time we won't have to wait, so let's do a quick test 6307 // first before we take the lock. 6308 if (!free_regions_coming()) { 6309 return; 6310 } 6311 6312 if (G1ConcRegionFreeingVerbose) { 6313 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6314 "waiting for free regions"); 6315 } 6316 6317 { 6318 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6319 while (free_regions_coming()) { 6320 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); 6321 } 6322 } 6323 6324 if (G1ConcRegionFreeingVerbose) { 6325 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " 6326 "done waiting for free regions"); 6327 } 6328 } 6329 6330 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 6331 assert(heap_lock_held_for_gc(), 6332 "the heap lock should already be held by or for this thread"); 6333 _young_list->push_region(hr); 6334 } 6335 6336 class NoYoungRegionsClosure: public HeapRegionClosure { 6337 private: 6338 bool _success; 6339 public: 6340 NoYoungRegionsClosure() : _success(true) { } 6341 bool doHeapRegion(HeapRegion* r) { 6342 if (r->is_young()) { 6343 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", 6344 r->bottom(), r->end()); 6345 _success = false; 6346 } 6347 return false; 6348 } 6349 bool success() { return _success; } 6350 }; 6351 6352 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { 6353 bool ret = _young_list->check_list_empty(check_sample); 6354 6355 if (check_heap) { 6356 NoYoungRegionsClosure closure; 6357 heap_region_iterate(&closure); 6358 ret = ret && closure.success(); 6359 } 6360 6361 return ret; 6362 } 6363 6364 class TearDownRegionSetsClosure : public HeapRegionClosure { 6365 private: 6366 HeapRegionSet *_old_set; 6367 6368 public: 6369 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 6370 6371 bool doHeapRegion(HeapRegion* r) { 6372 if (r->is_empty()) { 6373 // We ignore empty regions, we'll empty the free list afterwards 6374 } else if (r->is_young()) { 6375 // We ignore young regions, we'll empty the young list afterwards 6376 } else if (r->isHumongous()) { 6377 // We ignore humongous regions, we're not tearing down the 6378 // humongous region set 6379 } else { 6380 // The rest should be old 6381 _old_set->remove(r); 6382 } 6383 return false; 6384 } 6385 6386 ~TearDownRegionSetsClosure() { 6387 assert(_old_set->is_empty(), "post-condition"); 6388 } 6389 }; 6390 6391 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 6392 assert_at_safepoint(true /* should_be_vm_thread */); 6393 6394 if (!free_list_only) { 6395 TearDownRegionSetsClosure cl(&_old_set); 6396 heap_region_iterate(&cl); 6397 6398 // Note that emptying the _young_list is postponed and instead done as 6399 // the first step when rebuilding the regions sets again. The reason for 6400 // this is that during a full GC string deduplication needs to know if 6401 // a collected region was young or old when the full GC was initiated. 6402 } 6403 _free_list.remove_all(); 6404 } 6405 6406 class RebuildRegionSetsClosure : public HeapRegionClosure { 6407 private: 6408 bool _free_list_only; 6409 HeapRegionSet* _old_set; 6410 FreeRegionList* _free_list; 6411 size_t _total_used; 6412 6413 public: 6414 RebuildRegionSetsClosure(bool free_list_only, 6415 HeapRegionSet* old_set, FreeRegionList* free_list) : 6416 _free_list_only(free_list_only), 6417 _old_set(old_set), _free_list(free_list), _total_used(0) { 6418 assert(_free_list->is_empty(), "pre-condition"); 6419 if (!free_list_only) { 6420 assert(_old_set->is_empty(), "pre-condition"); 6421 } 6422 } 6423 6424 bool doHeapRegion(HeapRegion* r) { 6425 if (r->continuesHumongous()) { 6426 return false; 6427 } 6428 6429 if (r->is_empty()) { 6430 // Add free regions to the free list 6431 _free_list->add_as_tail(r); 6432 } else if (!_free_list_only) { 6433 assert(!r->is_young(), "we should not come across young regions"); 6434 6435 if (r->isHumongous()) { 6436 // We ignore humongous regions, we left the humongous set unchanged 6437 } else { 6438 // The rest should be old, add them to the old set 6439 _old_set->add(r); 6440 } 6441 _total_used += r->used(); 6442 } 6443 6444 return false; 6445 } 6446 6447 size_t total_used() { 6448 return _total_used; 6449 } 6450 }; 6451 6452 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 6453 assert_at_safepoint(true /* should_be_vm_thread */); 6454 6455 if (!free_list_only) { 6456 _young_list->empty_list(); 6457 } 6458 6459 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list); 6460 heap_region_iterate(&cl); 6461 6462 if (!free_list_only) { 6463 _summary_bytes_used = cl.total_used(); 6464 } 6465 assert(_summary_bytes_used == recalculate_used(), 6466 err_msg("inconsistent _summary_bytes_used, " 6467 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, 6468 _summary_bytes_used, recalculate_used())); 6469 } 6470 6471 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { 6472 _refine_cte_cl->set_concurrent(concurrent); 6473 } 6474 6475 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 6476 HeapRegion* hr = heap_region_containing(p); 6477 if (hr == NULL) { 6478 return false; 6479 } else { 6480 return hr->is_in(p); 6481 } 6482 } 6483 6484 // Methods for the mutator alloc region 6485 6486 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 6487 bool force) { 6488 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6489 assert(!force || g1_policy()->can_expand_young_list(), 6490 "if force is true we should be able to expand the young list"); 6491 bool young_list_full = g1_policy()->is_young_list_full(); 6492 if (force || !young_list_full) { 6493 HeapRegion* new_alloc_region = new_region(word_size, 6494 false /* is_old */, 6495 false /* do_expand */); 6496 if (new_alloc_region != NULL) { 6497 set_region_short_lived_locked(new_alloc_region); 6498 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); 6499 return new_alloc_region; 6500 } 6501 } 6502 return NULL; 6503 } 6504 6505 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 6506 size_t allocated_bytes) { 6507 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6508 assert(alloc_region->is_young(), "all mutator alloc regions should be young"); 6509 6510 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); 6511 _summary_bytes_used += allocated_bytes; 6512 _hr_printer.retire(alloc_region); 6513 // We update the eden sizes here, when the region is retired, 6514 // instead of when it's allocated, since this is the point that its 6515 // used space has been recored in _summary_bytes_used. 6516 g1mm()->update_eden_size(); 6517 } 6518 6519 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size, 6520 bool force) { 6521 return _g1h->new_mutator_alloc_region(word_size, force); 6522 } 6523 6524 void G1CollectedHeap::set_par_threads() { 6525 // Don't change the number of workers. Use the value previously set 6526 // in the workgroup. 6527 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise"); 6528 uint n_workers = workers()->active_workers(); 6529 assert(UseDynamicNumberOfGCThreads || 6530 n_workers == workers()->total_workers(), 6531 "Otherwise should be using the total number of workers"); 6532 if (n_workers == 0) { 6533 assert(false, "Should have been set in prior evacuation pause."); 6534 n_workers = ParallelGCThreads; 6535 workers()->set_active_workers(n_workers); 6536 } 6537 set_par_threads(n_workers); 6538 } 6539 6540 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region, 6541 size_t allocated_bytes) { 6542 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes); 6543 } 6544 6545 // Methods for the GC alloc regions 6546 6547 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, 6548 uint count, 6549 GCAllocPurpose ap) { 6550 assert(FreeList_lock->owned_by_self(), "pre-condition"); 6551 6552 if (count < g1_policy()->max_regions(ap)) { 6553 bool survivor = (ap == GCAllocForSurvived); 6554 HeapRegion* new_alloc_region = new_region(word_size, 6555 !survivor, 6556 true /* do_expand */); 6557 if (new_alloc_region != NULL) { 6558 // We really only need to do this for old regions given that we 6559 // should never scan survivors. But it doesn't hurt to do it 6560 // for survivors too. 6561 new_alloc_region->set_saved_mark(); 6562 if (survivor) { 6563 new_alloc_region->set_survivor(); 6564 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); 6565 } else { 6566 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); 6567 } 6568 bool during_im = g1_policy()->during_initial_mark_pause(); 6569 new_alloc_region->note_start_of_copying(during_im); 6570 return new_alloc_region; 6571 } else { 6572 g1_policy()->note_alloc_region_limit_reached(ap); 6573 } 6574 } 6575 return NULL; 6576 } 6577 6578 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 6579 size_t allocated_bytes, 6580 GCAllocPurpose ap) { 6581 bool during_im = g1_policy()->during_initial_mark_pause(); 6582 alloc_region->note_end_of_copying(during_im); 6583 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 6584 if (ap == GCAllocForSurvived) { 6585 young_list()->add_survivor_region(alloc_region); 6586 } else { 6587 _old_set.add(alloc_region); 6588 } 6589 _hr_printer.retire(alloc_region); 6590 } 6591 6592 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size, 6593 bool force) { 6594 assert(!force, "not supported for GC alloc regions"); 6595 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived); 6596 } 6597 6598 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region, 6599 size_t allocated_bytes) { 6600 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6601 GCAllocForSurvived); 6602 } 6603 6604 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size, 6605 bool force) { 6606 assert(!force, "not supported for GC alloc regions"); 6607 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured); 6608 } 6609 6610 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region, 6611 size_t allocated_bytes) { 6612 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, 6613 GCAllocForTenured); 6614 } 6615 // Heap region set verification 6616 6617 class VerifyRegionListsClosure : public HeapRegionClosure { 6618 private: 6619 HeapRegionSet* _old_set; 6620 HeapRegionSet* _humongous_set; 6621 FreeRegionList* _free_list; 6622 6623 public: 6624 HeapRegionSetCount _old_count; 6625 HeapRegionSetCount _humongous_count; 6626 HeapRegionSetCount _free_count; 6627 6628 VerifyRegionListsClosure(HeapRegionSet* old_set, 6629 HeapRegionSet* humongous_set, 6630 FreeRegionList* free_list) : 6631 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list), 6632 _old_count(), _humongous_count(), _free_count(){ } 6633 6634 bool doHeapRegion(HeapRegion* hr) { 6635 if (hr->continuesHumongous()) { 6636 return false; 6637 } 6638 6639 if (hr->is_young()) { 6640 // TODO 6641 } else if (hr->startsHumongous()) { 6642 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrs_index())); 6643 _humongous_count.increment(1u, hr->capacity()); 6644 } else if (hr->is_empty()) { 6645 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->hrs_index())); 6646 _free_count.increment(1u, hr->capacity()); 6647 } else { 6648 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrs_index())); 6649 _old_count.increment(1u, hr->capacity()); 6650 } 6651 return false; 6652 } 6653 6654 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) { 6655 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); 6656 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6657 old_set->total_capacity_bytes(), _old_count.capacity())); 6658 6659 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); 6660 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6661 humongous_set->total_capacity_bytes(), _humongous_count.capacity())); 6662 6663 guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length())); 6664 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 6665 free_list->total_capacity_bytes(), _free_count.capacity())); 6666 } 6667 }; 6668 6669 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 6670 HeapWord* bottom) { 6671 HeapWord* end = bottom + HeapRegion::GrainWords; 6672 MemRegion mr(bottom, end); 6673 assert(_g1_reserved.contains(mr), "invariant"); 6674 // This might return NULL if the allocation fails 6675 return new HeapRegion(hrs_index, _bot_shared, mr); 6676 } 6677 6678 void G1CollectedHeap::verify_region_sets() { 6679 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 6680 6681 // First, check the explicit lists. 6682 _free_list.verify_list(); 6683 { 6684 // Given that a concurrent operation might be adding regions to 6685 // the secondary free list we have to take the lock before 6686 // verifying it. 6687 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 6688 _secondary_free_list.verify_list(); 6689 } 6690 6691 // If a concurrent region freeing operation is in progress it will 6692 // be difficult to correctly attributed any free regions we come 6693 // across to the correct free list given that they might belong to 6694 // one of several (free_list, secondary_free_list, any local lists, 6695 // etc.). So, if that's the case we will skip the rest of the 6696 // verification operation. Alternatively, waiting for the concurrent 6697 // operation to complete will have a non-trivial effect on the GC's 6698 // operation (no concurrent operation will last longer than the 6699 // interval between two calls to verification) and it might hide 6700 // any issues that we would like to catch during testing. 6701 if (free_regions_coming()) { 6702 return; 6703 } 6704 6705 // Make sure we append the secondary_free_list on the free_list so 6706 // that all free regions we will come across can be safely 6707 // attributed to the free_list. 6708 append_secondary_free_list_if_not_empty_with_lock(); 6709 6710 // Finally, make sure that the region accounting in the lists is 6711 // consistent with what we see in the heap. 6712 6713 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list); 6714 heap_region_iterate(&cl); 6715 cl.verify_counts(&_old_set, &_humongous_set, &_free_list); 6716 } 6717 6718 // Optimized nmethod scanning 6719 6720 class RegisterNMethodOopClosure: public OopClosure { 6721 G1CollectedHeap* _g1h; 6722 nmethod* _nm; 6723 6724 template <class T> void do_oop_work(T* p) { 6725 T heap_oop = oopDesc::load_heap_oop(p); 6726 if (!oopDesc::is_null(heap_oop)) { 6727 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6728 HeapRegion* hr = _g1h->heap_region_containing(obj); 6729 assert(!hr->continuesHumongous(), 6730 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6731 " starting at "HR_FORMAT, 6732 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6733 6734 // HeapRegion::add_strong_code_root() avoids adding duplicate 6735 // entries but having duplicates is OK since we "mark" nmethods 6736 // as visited when we scan the strong code root lists during the GC. 6737 hr->add_strong_code_root(_nm); 6738 assert(hr->rem_set()->strong_code_roots_list_contains(_nm), 6739 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT, 6740 _nm, HR_FORMAT_PARAMS(hr))); 6741 } 6742 } 6743 6744 public: 6745 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6746 _g1h(g1h), _nm(nm) {} 6747 6748 void do_oop(oop* p) { do_oop_work(p); } 6749 void do_oop(narrowOop* p) { do_oop_work(p); } 6750 }; 6751 6752 class UnregisterNMethodOopClosure: public OopClosure { 6753 G1CollectedHeap* _g1h; 6754 nmethod* _nm; 6755 6756 template <class T> void do_oop_work(T* p) { 6757 T heap_oop = oopDesc::load_heap_oop(p); 6758 if (!oopDesc::is_null(heap_oop)) { 6759 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6760 HeapRegion* hr = _g1h->heap_region_containing(obj); 6761 assert(!hr->continuesHumongous(), 6762 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT 6763 " starting at "HR_FORMAT, 6764 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); 6765 6766 hr->remove_strong_code_root(_nm); 6767 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm), 6768 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT, 6769 _nm, HR_FORMAT_PARAMS(hr))); 6770 } 6771 } 6772 6773 public: 6774 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 6775 _g1h(g1h), _nm(nm) {} 6776 6777 void do_oop(oop* p) { do_oop_work(p); } 6778 void do_oop(narrowOop* p) { do_oop_work(p); } 6779 }; 6780 6781 void G1CollectedHeap::register_nmethod(nmethod* nm) { 6782 CollectedHeap::register_nmethod(nm); 6783 6784 guarantee(nm != NULL, "sanity"); 6785 RegisterNMethodOopClosure reg_cl(this, nm); 6786 nm->oops_do(®_cl); 6787 } 6788 6789 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 6790 CollectedHeap::unregister_nmethod(nm); 6791 6792 guarantee(nm != NULL, "sanity"); 6793 UnregisterNMethodOopClosure reg_cl(this, nm); 6794 nm->oops_do(®_cl, true); 6795 } 6796 6797 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure { 6798 public: 6799 bool doHeapRegion(HeapRegion *hr) { 6800 assert(!hr->isHumongous(), 6801 err_msg("humongous region "HR_FORMAT" should not have been added to collection set", 6802 HR_FORMAT_PARAMS(hr))); 6803 hr->migrate_strong_code_roots(); 6804 return false; 6805 } 6806 }; 6807 6808 void G1CollectedHeap::migrate_strong_code_roots() { 6809 MigrateCodeRootsHeapRegionClosure cl; 6810 double migrate_start = os::elapsedTime(); 6811 collection_set_iterate(&cl); 6812 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0; 6813 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms); 6814 } 6815 6816 void G1CollectedHeap::purge_code_root_memory() { 6817 double purge_start = os::elapsedTime(); 6818 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent); 6819 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 6820 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 6821 } 6822 6823 // Mark all the code roots that point into regions *not* in the 6824 // collection set. 6825 // 6826 // Note we do not want to use a "marking" CodeBlobToOopClosure while 6827 // walking the the code roots lists of regions not in the collection 6828 // set. Suppose we have an nmethod (M) that points to objects in two 6829 // separate regions - one in the collection set (R1) and one not (R2). 6830 // Using a "marking" CodeBlobToOopClosure here would result in "marking" 6831 // nmethod M when walking the code roots for R1. When we come to scan 6832 // the code roots for R2, we would see that M is already marked and it 6833 // would be skipped and the objects in R2 that are referenced from M 6834 // would not be evacuated. 6835 6836 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure { 6837 6838 class MarkStrongCodeRootOopClosure: public OopClosure { 6839 ConcurrentMark* _cm; 6840 HeapRegion* _hr; 6841 uint _worker_id; 6842 6843 template <class T> void do_oop_work(T* p) { 6844 T heap_oop = oopDesc::load_heap_oop(p); 6845 if (!oopDesc::is_null(heap_oop)) { 6846 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 6847 // Only mark objects in the region (which is assumed 6848 // to be not in the collection set). 6849 if (_hr->is_in(obj)) { 6850 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); 6851 } 6852 } 6853 } 6854 6855 public: 6856 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) : 6857 _cm(cm), _hr(hr), _worker_id(worker_id) { 6858 assert(!_hr->in_collection_set(), "sanity"); 6859 } 6860 6861 void do_oop(narrowOop* p) { do_oop_work(p); } 6862 void do_oop(oop* p) { do_oop_work(p); } 6863 }; 6864 6865 MarkStrongCodeRootOopClosure _oop_cl; 6866 6867 public: 6868 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id): 6869 _oop_cl(cm, hr, worker_id) {} 6870 6871 void do_code_blob(CodeBlob* cb) { 6872 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null(); 6873 if (nm != NULL) { 6874 nm->oops_do(&_oop_cl); 6875 } 6876 } 6877 }; 6878 6879 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure { 6880 G1CollectedHeap* _g1h; 6881 uint _worker_id; 6882 6883 public: 6884 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) : 6885 _g1h(g1h), _worker_id(worker_id) {} 6886 6887 bool doHeapRegion(HeapRegion *hr) { 6888 HeapRegionRemSet* hrrs = hr->rem_set(); 6889 if (hr->continuesHumongous()) { 6890 // Code roots should never be attached to a continuation of a humongous region 6891 assert(hrrs->strong_code_roots_list_length() == 0, 6892 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT 6893 " starting at "HR_FORMAT", but has "SIZE_FORMAT, 6894 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()), 6895 hrrs->strong_code_roots_list_length())); 6896 return false; 6897 } 6898 6899 if (hr->in_collection_set()) { 6900 // Don't mark code roots into regions in the collection set here. 6901 // They will be marked when we scan them. 6902 return false; 6903 } 6904 6905 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id); 6906 hr->strong_code_roots_do(&cb_cl); 6907 return false; 6908 } 6909 }; 6910 6911 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) { 6912 MarkStrongCodeRootsHRClosure cl(this, worker_id); 6913 if (G1CollectedHeap::use_parallel_gc_threads()) { 6914 heap_region_par_iterate_chunked(&cl, 6915 worker_id, 6916 workers()->active_workers(), 6917 HeapRegion::ParMarkRootClaimValue); 6918 } else { 6919 heap_region_iterate(&cl); 6920 } 6921 } 6922 6923 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 6924 G1CollectedHeap* _g1h; 6925 6926 public: 6927 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 6928 _g1h(g1h) {} 6929 6930 void do_code_blob(CodeBlob* cb) { 6931 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 6932 if (nm == NULL) { 6933 return; 6934 } 6935 6936 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) { 6937 _g1h->register_nmethod(nm); 6938 } 6939 } 6940 }; 6941 6942 void G1CollectedHeap::rebuild_strong_code_roots() { 6943 RebuildStrongCodeRootClosure blob_cl(this); 6944 CodeCache::blobs_do(&blob_cl); 6945 }