1 /* 2 * Copyright (c) 1997, 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 "gc_implementation/shared/gcTimer.hpp" 27 #include "gc_implementation/shared/gcTrace.hpp" 28 #include "gc_implementation/shared/spaceDecorator.hpp" 29 #include "gc_interface/collectedHeap.inline.hpp" 30 #include "memory/allocation.inline.hpp" 31 #include "memory/blockOffsetTable.inline.hpp" 32 #include "memory/cardTableRS.hpp" 33 #include "memory/gcLocker.inline.hpp" 34 #include "memory/genCollectedHeap.hpp" 35 #include "memory/genMarkSweep.hpp" 36 #include "memory/genOopClosures.hpp" 37 #include "memory/genOopClosures.inline.hpp" 38 #include "memory/generation.hpp" 39 #include "memory/generation.inline.hpp" 40 #include "memory/space.inline.hpp" 41 #include "oops/oop.inline.hpp" 42 #include "runtime/java.hpp" 43 #include "utilities/copy.hpp" 44 #include "utilities/events.hpp" 45 46 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 47 48 Generation::Generation(ReservedSpace rs, size_t initial_size, int level) : 49 _level(level), 50 _ref_processor(NULL) { 51 if (!_virtual_space.initialize(rs, initial_size)) { 52 vm_exit_during_initialization("Could not reserve enough space for " 53 "object heap"); 54 } 55 // Mangle all of the the initial generation. 56 if (ZapUnusedHeapArea) { 57 MemRegion mangle_region((HeapWord*)_virtual_space.low(), 58 (HeapWord*)_virtual_space.high()); 59 SpaceMangler::mangle_region(mangle_region); 60 } 61 _reserved = MemRegion((HeapWord*)_virtual_space.low_boundary(), 62 (HeapWord*)_virtual_space.high_boundary()); 63 } 64 65 GenerationSpec* Generation::spec() { 66 GenCollectedHeap* gch = GenCollectedHeap::heap(); 67 assert(0 <= level() && level() < gch->_n_gens, "Bad gen level"); 68 return gch->_gen_specs[level()]; 69 } 70 71 size_t Generation::max_capacity() const { 72 return reserved().byte_size(); 73 } 74 75 void Generation::print_heap_change(size_t prev_used) const { 76 if (PrintGCDetails && Verbose) { 77 gclog_or_tty->print(" " SIZE_FORMAT 78 "->" SIZE_FORMAT 79 "(" SIZE_FORMAT ")", 80 prev_used, used(), capacity()); 81 } else { 82 gclog_or_tty->print(" " SIZE_FORMAT "K" 83 "->" SIZE_FORMAT "K" 84 "(" SIZE_FORMAT "K)", 85 prev_used / K, used() / K, capacity() / K); 86 } 87 } 88 89 // By default we get a single threaded default reference processor; 90 // generations needing multi-threaded refs processing or discovery override this method. 91 void Generation::ref_processor_init() { 92 assert(_ref_processor == NULL, "a reference processor already exists"); 93 assert(!_reserved.is_empty(), "empty generation?"); 94 _ref_processor = new ReferenceProcessor(_reserved); // a vanilla reference processor 95 if (_ref_processor == NULL) { 96 vm_exit_during_initialization("Could not allocate ReferenceProcessor object"); 97 } 98 } 99 100 void Generation::print() const { print_on(tty); } 101 102 void Generation::print_on(outputStream* st) const { 103 st->print(" %-20s", name()); 104 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 105 capacity()/K, used()/K); 106 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 107 _virtual_space.low_boundary(), 108 _virtual_space.high(), 109 _virtual_space.high_boundary()); 110 } 111 112 void Generation::print_summary_info() { print_summary_info_on(tty); } 113 114 void Generation::print_summary_info_on(outputStream* st) { 115 StatRecord* sr = stat_record(); 116 double time = sr->accumulated_time.seconds(); 117 st->print_cr("[Accumulated GC generation %d time %3.7f secs, " 118 "%d GC's, avg GC time %3.7f]", 119 level(), time, sr->invocations, 120 sr->invocations > 0 ? time / sr->invocations : 0.0); 121 } 122 123 // Utility iterator classes 124 125 class GenerationIsInReservedClosure : public SpaceClosure { 126 public: 127 const void* _p; 128 Space* sp; 129 virtual void do_space(Space* s) { 130 if (sp == NULL) { 131 if (s->is_in_reserved(_p)) sp = s; 132 } 133 } 134 GenerationIsInReservedClosure(const void* p) : _p(p), sp(NULL) {} 135 }; 136 137 class GenerationIsInClosure : public SpaceClosure { 138 public: 139 const void* _p; 140 Space* sp; 141 virtual void do_space(Space* s) { 142 if (sp == NULL) { 143 if (s->is_in(_p)) sp = s; 144 } 145 } 146 GenerationIsInClosure(const void* p) : _p(p), sp(NULL) {} 147 }; 148 149 bool Generation::is_in(const void* p) const { 150 GenerationIsInClosure blk(p); 151 ((Generation*)this)->space_iterate(&blk); 152 return blk.sp != NULL; 153 } 154 155 DefNewGeneration* Generation::as_DefNewGeneration() { 156 assert((kind() == Generation::DefNew) || 157 (kind() == Generation::ParNew), 158 "Wrong youngest generation type"); 159 return (DefNewGeneration*) this; 160 } 161 162 Generation* Generation::next_gen() const { 163 GenCollectedHeap* gch = GenCollectedHeap::heap(); 164 int next = level() + 1; 165 if (next < gch->_n_gens) { 166 return gch->_gens[next]; 167 } else { 168 return NULL; 169 } 170 } 171 172 size_t Generation::max_contiguous_available() const { 173 // The largest number of contiguous free words in this or any higher generation. 174 size_t max = 0; 175 for (const Generation* gen = this; gen != NULL; gen = gen->next_gen()) { 176 size_t avail = gen->contiguous_available(); 177 if (avail > max) { 178 max = avail; 179 } 180 } 181 return max; 182 } 183 184 bool Generation::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const { 185 size_t available = max_contiguous_available(); 186 bool res = (available >= max_promotion_in_bytes); 187 if (PrintGC && Verbose) { 188 gclog_or_tty->print_cr( 189 "Generation: promo attempt is%s safe: available("SIZE_FORMAT") %s max_promo("SIZE_FORMAT")", 190 res? "":" not", available, res? ">=":"<", 191 max_promotion_in_bytes); 192 } 193 return res; 194 } 195 196 // Ignores "ref" and calls allocate(). 197 oop Generation::promote(oop obj, size_t obj_size) { 198 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); 199 200 #ifndef PRODUCT 201 if (Universe::heap()->promotion_should_fail()) { 202 return NULL; 203 } 204 #endif // #ifndef PRODUCT 205 206 HeapWord* result = allocate(obj_size, false); 207 if (result != NULL) { 208 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size); 209 return oop(result); 210 } else { 211 GenCollectedHeap* gch = GenCollectedHeap::heap(); 212 return gch->handle_failed_promotion(this, obj, obj_size); 213 } 214 } 215 216 oop Generation::par_promote(int thread_num, 217 oop obj, markOop m, size_t word_sz) { 218 // Could do a bad general impl here that gets a lock. But no. 219 ShouldNotCallThis(); 220 return NULL; 221 } 222 223 void Generation::par_promote_alloc_undo(int thread_num, 224 HeapWord* obj, size_t word_sz) { 225 // Could do a bad general impl here that gets a lock. But no. 226 guarantee(false, "No good general implementation."); 227 } 228 229 Space* Generation::space_containing(const void* p) const { 230 GenerationIsInReservedClosure blk(p); 231 // Cast away const 232 ((Generation*)this)->space_iterate(&blk); 233 return blk.sp; 234 } 235 236 // Some of these are mediocre general implementations. Should be 237 // overridden to get better performance. 238 239 class GenerationBlockStartClosure : public SpaceClosure { 240 public: 241 const void* _p; 242 HeapWord* _start; 243 virtual void do_space(Space* s) { 244 if (_start == NULL && s->is_in_reserved(_p)) { 245 _start = s->block_start(_p); 246 } 247 } 248 GenerationBlockStartClosure(const void* p) { _p = p; _start = NULL; } 249 }; 250 251 HeapWord* Generation::block_start(const void* p) const { 252 GenerationBlockStartClosure blk(p); 253 // Cast away const 254 ((Generation*)this)->space_iterate(&blk); 255 return blk._start; 256 } 257 258 class GenerationBlockSizeClosure : public SpaceClosure { 259 public: 260 const HeapWord* _p; 261 size_t size; 262 virtual void do_space(Space* s) { 263 if (size == 0 && s->is_in_reserved(_p)) { 264 size = s->block_size(_p); 265 } 266 } 267 GenerationBlockSizeClosure(const HeapWord* p) { _p = p; size = 0; } 268 }; 269 270 size_t Generation::block_size(const HeapWord* p) const { 271 GenerationBlockSizeClosure blk(p); 272 // Cast away const 273 ((Generation*)this)->space_iterate(&blk); 274 assert(blk.size > 0, "seems reasonable"); 275 return blk.size; 276 } 277 278 class GenerationBlockIsObjClosure : public SpaceClosure { 279 public: 280 const HeapWord* _p; 281 bool is_obj; 282 virtual void do_space(Space* s) { 283 if (!is_obj && s->is_in_reserved(_p)) { 284 is_obj |= s->block_is_obj(_p); 285 } 286 } 287 GenerationBlockIsObjClosure(const HeapWord* p) { _p = p; is_obj = false; } 288 }; 289 290 bool Generation::block_is_obj(const HeapWord* p) const { 291 GenerationBlockIsObjClosure blk(p); 292 // Cast away const 293 ((Generation*)this)->space_iterate(&blk); 294 return blk.is_obj; 295 } 296 297 class GenerationOopIterateClosure : public SpaceClosure { 298 public: 299 ExtendedOopClosure* _cl; 300 virtual void do_space(Space* s) { 301 s->oop_iterate(_cl); 302 } 303 GenerationOopIterateClosure(ExtendedOopClosure* cl) : 304 _cl(cl) {} 305 }; 306 307 void Generation::oop_iterate(ExtendedOopClosure* cl) { 308 GenerationOopIterateClosure blk(cl); 309 space_iterate(&blk); 310 } 311 312 void Generation::younger_refs_in_space_iterate(Space* sp, 313 OopsInGenClosure* cl) { 314 GenRemSet* rs = SharedHeap::heap()->rem_set(); 315 rs->younger_refs_in_space_iterate(sp, cl); 316 } 317 318 class GenerationObjIterateClosure : public SpaceClosure { 319 private: 320 ObjectClosure* _cl; 321 public: 322 virtual void do_space(Space* s) { 323 s->object_iterate(_cl); 324 } 325 GenerationObjIterateClosure(ObjectClosure* cl) : _cl(cl) {} 326 }; 327 328 void Generation::object_iterate(ObjectClosure* cl) { 329 GenerationObjIterateClosure blk(cl); 330 space_iterate(&blk); 331 } 332 333 class GenerationSafeObjIterateClosure : public SpaceClosure { 334 private: 335 ObjectClosure* _cl; 336 public: 337 virtual void do_space(Space* s) { 338 s->safe_object_iterate(_cl); 339 } 340 GenerationSafeObjIterateClosure(ObjectClosure* cl) : _cl(cl) {} 341 }; 342 343 void Generation::safe_object_iterate(ObjectClosure* cl) { 344 GenerationSafeObjIterateClosure blk(cl); 345 space_iterate(&blk); 346 } 347 348 void Generation::prepare_for_compaction(CompactPoint* cp) { 349 // Generic implementation, can be specialized 350 CompactibleSpace* space = first_compaction_space(); 351 while (space != NULL) { 352 space->prepare_for_compaction(cp); 353 space = space->next_compaction_space(); 354 } 355 } 356 357 class AdjustPointersClosure: public SpaceClosure { 358 public: 359 void do_space(Space* sp) { 360 sp->adjust_pointers(); 361 } 362 }; 363 364 void Generation::adjust_pointers() { 365 // Note that this is done over all spaces, not just the compactible 366 // ones. 367 AdjustPointersClosure blk; 368 space_iterate(&blk, true); 369 } 370 371 void Generation::compact() { 372 CompactibleSpace* sp = first_compaction_space(); 373 while (sp != NULL) { 374 sp->compact(); 375 sp = sp->next_compaction_space(); 376 } 377 } 378 379 CardGeneration::CardGeneration(ReservedSpace rs, size_t initial_byte_size, 380 int level, 381 GenRemSet* remset) : 382 Generation(rs, initial_byte_size, level), _rs(remset), 383 _shrink_factor(0), _min_heap_delta_bytes(), _capacity_at_prologue(), 384 _used_at_prologue() 385 { 386 HeapWord* start = (HeapWord*)rs.base(); 387 size_t reserved_byte_size = rs.size(); 388 assert((uintptr_t(start) & 3) == 0, "bad alignment"); 389 assert((reserved_byte_size & 3) == 0, "bad alignment"); 390 MemRegion reserved_mr(start, heap_word_size(reserved_byte_size)); 391 _bts = new BlockOffsetSharedArray(reserved_mr, 392 heap_word_size(initial_byte_size)); 393 MemRegion committed_mr(start, heap_word_size(initial_byte_size)); 394 _rs->resize_covered_region(committed_mr); 395 if (_bts == NULL) 396 vm_exit_during_initialization("Could not allocate a BlockOffsetArray"); 397 398 // Verify that the start and end of this generation is the start of a card. 399 // If this wasn't true, a single card could span more than on generation, 400 // which would cause problems when we commit/uncommit memory, and when we 401 // clear and dirty cards. 402 guarantee(_rs->is_aligned(reserved_mr.start()), "generation must be card aligned"); 403 if (reserved_mr.end() != Universe::heap()->reserved_region().end()) { 404 // Don't check at the very end of the heap as we'll assert that we're probing off 405 // the end if we try. 406 guarantee(_rs->is_aligned(reserved_mr.end()), "generation must be card aligned"); 407 } 408 _min_heap_delta_bytes = MinHeapDeltaBytes; 409 _capacity_at_prologue = initial_byte_size; 410 _used_at_prologue = 0; 411 } 412 413 bool CardGeneration::expand(size_t bytes, size_t expand_bytes) { 414 assert_locked_or_safepoint(Heap_lock); 415 if (bytes == 0) { 416 return true; // That's what grow_by(0) would return 417 } 418 size_t aligned_bytes = ReservedSpace::page_align_size_up(bytes); 419 if (aligned_bytes == 0){ 420 // The alignment caused the number of bytes to wrap. An expand_by(0) will 421 // return true with the implication that an expansion was done when it 422 // was not. A call to expand implies a best effort to expand by "bytes" 423 // but not a guarantee. Align down to give a best effort. This is likely 424 // the most that the generation can expand since it has some capacity to 425 // start with. 426 aligned_bytes = ReservedSpace::page_align_size_down(bytes); 427 } 428 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 429 bool success = false; 430 if (aligned_expand_bytes > aligned_bytes) { 431 success = grow_by(aligned_expand_bytes); 432 } 433 if (!success) { 434 success = grow_by(aligned_bytes); 435 } 436 if (!success) { 437 success = grow_to_reserved(); 438 } 439 if (PrintGC && Verbose) { 440 if (success && GC_locker::is_active_and_needs_gc()) { 441 gclog_or_tty->print_cr("Garbage collection disabled, expanded heap instead"); 442 } 443 } 444 445 return success; 446 } 447 448 449 // No young generation references, clear this generation's cards. 450 void CardGeneration::clear_remembered_set() { 451 _rs->clear(reserved()); 452 } 453 454 455 // Objects in this generation may have moved, invalidate this 456 // generation's cards. 457 void CardGeneration::invalidate_remembered_set() { 458 _rs->invalidate(used_region()); 459 } 460 461 462 void CardGeneration::compute_new_size() { 463 assert(_shrink_factor <= 100, "invalid shrink factor"); 464 size_t current_shrink_factor = _shrink_factor; 465 _shrink_factor = 0; 466 467 // We don't have floating point command-line arguments 468 // Note: argument processing ensures that MinHeapFreeRatio < 100. 469 const double minimum_free_percentage = MinHeapFreeRatio / 100.0; 470 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 471 472 // Compute some numbers about the state of the heap. 473 const size_t used_after_gc = used(); 474 const size_t capacity_after_gc = capacity(); 475 476 const double min_tmp = used_after_gc / maximum_used_percentage; 477 size_t minimum_desired_capacity = (size_t)MIN2(min_tmp, double(max_uintx)); 478 // Don't shrink less than the initial generation size 479 minimum_desired_capacity = MAX2(minimum_desired_capacity, 480 spec()->init_size()); 481 assert(used_after_gc <= minimum_desired_capacity, "sanity check"); 482 483 if (PrintGC && Verbose) { 484 const size_t free_after_gc = free(); 485 const double free_percentage = ((double)free_after_gc) / capacity_after_gc; 486 gclog_or_tty->print_cr("TenuredGeneration::compute_new_size: "); 487 gclog_or_tty->print_cr(" " 488 " minimum_free_percentage: %6.2f" 489 " maximum_used_percentage: %6.2f", 490 minimum_free_percentage, 491 maximum_used_percentage); 492 gclog_or_tty->print_cr(" " 493 " free_after_gc : %6.1fK" 494 " used_after_gc : %6.1fK" 495 " capacity_after_gc : %6.1fK", 496 free_after_gc / (double) K, 497 used_after_gc / (double) K, 498 capacity_after_gc / (double) K); 499 gclog_or_tty->print_cr(" " 500 " free_percentage: %6.2f", 501 free_percentage); 502 } 503 504 if (capacity_after_gc < minimum_desired_capacity) { 505 // If we have less free space than we want then expand 506 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 507 // Don't expand unless it's significant 508 if (expand_bytes >= _min_heap_delta_bytes) { 509 expand(expand_bytes, 0); // safe if expansion fails 510 } 511 if (PrintGC && Verbose) { 512 gclog_or_tty->print_cr(" expanding:" 513 " minimum_desired_capacity: %6.1fK" 514 " expand_bytes: %6.1fK" 515 " _min_heap_delta_bytes: %6.1fK", 516 minimum_desired_capacity / (double) K, 517 expand_bytes / (double) K, 518 _min_heap_delta_bytes / (double) K); 519 } 520 return; 521 } 522 523 // No expansion, now see if we want to shrink 524 size_t shrink_bytes = 0; 525 // We would never want to shrink more than this 526 size_t max_shrink_bytes = capacity_after_gc - minimum_desired_capacity; 527 528 if (MaxHeapFreeRatio < 100) { 529 const double maximum_free_percentage = MaxHeapFreeRatio / 100.0; 530 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 531 const double max_tmp = used_after_gc / minimum_used_percentage; 532 size_t maximum_desired_capacity = (size_t)MIN2(max_tmp, double(max_uintx)); 533 maximum_desired_capacity = MAX2(maximum_desired_capacity, 534 spec()->init_size()); 535 if (PrintGC && Verbose) { 536 gclog_or_tty->print_cr(" " 537 " maximum_free_percentage: %6.2f" 538 " minimum_used_percentage: %6.2f", 539 maximum_free_percentage, 540 minimum_used_percentage); 541 gclog_or_tty->print_cr(" " 542 " _capacity_at_prologue: %6.1fK" 543 " minimum_desired_capacity: %6.1fK" 544 " maximum_desired_capacity: %6.1fK", 545 _capacity_at_prologue / (double) K, 546 minimum_desired_capacity / (double) K, 547 maximum_desired_capacity / (double) K); 548 } 549 assert(minimum_desired_capacity <= maximum_desired_capacity, 550 "sanity check"); 551 552 if (capacity_after_gc > maximum_desired_capacity) { 553 // Capacity too large, compute shrinking size 554 shrink_bytes = capacity_after_gc - maximum_desired_capacity; 555 // We don't want shrink all the way back to initSize if people call 556 // System.gc(), because some programs do that between "phases" and then 557 // we'd just have to grow the heap up again for the next phase. So we 558 // damp the shrinking: 0% on the first call, 10% on the second call, 40% 559 // on the third call, and 100% by the fourth call. But if we recompute 560 // size without shrinking, it goes back to 0%. 561 shrink_bytes = shrink_bytes / 100 * current_shrink_factor; 562 assert(shrink_bytes <= max_shrink_bytes, "invalid shrink size"); 563 if (current_shrink_factor == 0) { 564 _shrink_factor = 10; 565 } else { 566 _shrink_factor = MIN2(current_shrink_factor * 4, (size_t) 100); 567 } 568 if (PrintGC && Verbose) { 569 gclog_or_tty->print_cr(" " 570 " shrinking:" 571 " initSize: %.1fK" 572 " maximum_desired_capacity: %.1fK", 573 spec()->init_size() / (double) K, 574 maximum_desired_capacity / (double) K); 575 gclog_or_tty->print_cr(" " 576 " shrink_bytes: %.1fK" 577 " current_shrink_factor: " SIZE_FORMAT 578 " new shrink factor: " SIZE_FORMAT 579 " _min_heap_delta_bytes: %.1fK", 580 shrink_bytes / (double) K, 581 current_shrink_factor, 582 _shrink_factor, 583 _min_heap_delta_bytes / (double) K); 584 } 585 } 586 } 587 588 if (capacity_after_gc > _capacity_at_prologue) { 589 // We might have expanded for promotions, in which case we might want to 590 // take back that expansion if there's room after GC. That keeps us from 591 // stretching the heap with promotions when there's plenty of room. 592 size_t expansion_for_promotion = capacity_after_gc - _capacity_at_prologue; 593 expansion_for_promotion = MIN2(expansion_for_promotion, max_shrink_bytes); 594 // We have two shrinking computations, take the largest 595 shrink_bytes = MAX2(shrink_bytes, expansion_for_promotion); 596 assert(shrink_bytes <= max_shrink_bytes, "invalid shrink size"); 597 if (PrintGC && Verbose) { 598 gclog_or_tty->print_cr(" " 599 " aggressive shrinking:" 600 " _capacity_at_prologue: %.1fK" 601 " capacity_after_gc: %.1fK" 602 " expansion_for_promotion: %.1fK" 603 " shrink_bytes: %.1fK", 604 capacity_after_gc / (double) K, 605 _capacity_at_prologue / (double) K, 606 expansion_for_promotion / (double) K, 607 shrink_bytes / (double) K); 608 } 609 } 610 // Don't shrink unless it's significant 611 if (shrink_bytes >= _min_heap_delta_bytes) { 612 shrink(shrink_bytes); 613 } 614 } 615 616 // Currently nothing to do. 617 void CardGeneration::prepare_for_verify() {} 618 619 620 void OneContigSpaceCardGeneration::collect(bool full, 621 bool clear_all_soft_refs, 622 size_t size, 623 bool is_tlab) { 624 GenCollectedHeap* gch = GenCollectedHeap::heap(); 625 626 SpecializationStats::clear(); 627 // Temporarily expand the span of our ref processor, so 628 // refs discovery is over the entire heap, not just this generation 629 ReferenceProcessorSpanMutator 630 x(ref_processor(), gch->reserved_region()); 631 632 STWGCTimer* gc_timer = GenMarkSweep::gc_timer(); 633 gc_timer->register_gc_start(); 634 635 SerialOldTracer* gc_tracer = GenMarkSweep::gc_tracer(); 636 gc_tracer->report_gc_start(gch->gc_cause(), gc_timer->gc_start()); 637 638 GenMarkSweep::invoke_at_safepoint(_level, ref_processor(), clear_all_soft_refs); 639 640 gc_timer->register_gc_end(); 641 642 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 643 644 SpecializationStats::print(); 645 } 646 647 HeapWord* 648 OneContigSpaceCardGeneration::expand_and_allocate(size_t word_size, 649 bool is_tlab, 650 bool parallel) { 651 assert(!is_tlab, "OneContigSpaceCardGeneration does not support TLAB allocation"); 652 if (parallel) { 653 MutexLocker x(ParGCRareEvent_lock); 654 HeapWord* result = NULL; 655 size_t byte_size = word_size * HeapWordSize; 656 while (true) { 657 expand(byte_size, _min_heap_delta_bytes); 658 if (GCExpandToAllocateDelayMillis > 0) { 659 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); 660 } 661 result = _the_space->par_allocate(word_size); 662 if ( result != NULL) { 663 return result; 664 } else { 665 // If there's not enough expansion space available, give up. 666 if (_virtual_space.uncommitted_size() < byte_size) { 667 return NULL; 668 } 669 // else try again 670 } 671 } 672 } else { 673 expand(word_size*HeapWordSize, _min_heap_delta_bytes); 674 return _the_space->allocate(word_size); 675 } 676 } 677 678 bool OneContigSpaceCardGeneration::expand(size_t bytes, size_t expand_bytes) { 679 GCMutexLocker x(ExpandHeap_lock); 680 return CardGeneration::expand(bytes, expand_bytes); 681 } 682 683 684 void OneContigSpaceCardGeneration::shrink(size_t bytes) { 685 assert_locked_or_safepoint(ExpandHeap_lock); 686 size_t size = ReservedSpace::page_align_size_down(bytes); 687 if (size > 0) { 688 shrink_by(size); 689 } 690 } 691 692 693 size_t OneContigSpaceCardGeneration::capacity() const { 694 return _the_space->capacity(); 695 } 696 697 698 size_t OneContigSpaceCardGeneration::used() const { 699 return _the_space->used(); 700 } 701 702 703 size_t OneContigSpaceCardGeneration::free() const { 704 return _the_space->free(); 705 } 706 707 MemRegion OneContigSpaceCardGeneration::used_region() const { 708 return the_space()->used_region(); 709 } 710 711 size_t OneContigSpaceCardGeneration::unsafe_max_alloc_nogc() const { 712 return _the_space->free(); 713 } 714 715 size_t OneContigSpaceCardGeneration::contiguous_available() const { 716 return _the_space->free() + _virtual_space.uncommitted_size(); 717 } 718 719 bool OneContigSpaceCardGeneration::grow_by(size_t bytes) { 720 assert_locked_or_safepoint(ExpandHeap_lock); 721 bool result = _virtual_space.expand_by(bytes); 722 if (result) { 723 size_t new_word_size = 724 heap_word_size(_virtual_space.committed_size()); 725 MemRegion mr(_the_space->bottom(), new_word_size); 726 // Expand card table 727 Universe::heap()->barrier_set()->resize_covered_region(mr); 728 // Expand shared block offset array 729 _bts->resize(new_word_size); 730 731 // Fix for bug #4668531 732 if (ZapUnusedHeapArea) { 733 MemRegion mangle_region(_the_space->end(), 734 (HeapWord*)_virtual_space.high()); 735 SpaceMangler::mangle_region(mangle_region); 736 } 737 738 // Expand space -- also expands space's BOT 739 // (which uses (part of) shared array above) 740 _the_space->set_end((HeapWord*)_virtual_space.high()); 741 742 // update the space and generation capacity counters 743 update_counters(); 744 745 if (Verbose && PrintGC) { 746 size_t new_mem_size = _virtual_space.committed_size(); 747 size_t old_mem_size = new_mem_size - bytes; 748 gclog_or_tty->print_cr("Expanding %s from " SIZE_FORMAT "K by " 749 SIZE_FORMAT "K to " SIZE_FORMAT "K", 750 name(), old_mem_size/K, bytes/K, new_mem_size/K); 751 } 752 } 753 return result; 754 } 755 756 757 bool OneContigSpaceCardGeneration::grow_to_reserved() { 758 assert_locked_or_safepoint(ExpandHeap_lock); 759 bool success = true; 760 const size_t remaining_bytes = _virtual_space.uncommitted_size(); 761 if (remaining_bytes > 0) { 762 success = grow_by(remaining_bytes); 763 DEBUG_ONLY(if (!success) warning("grow to reserved failed");) 764 } 765 return success; 766 } 767 768 void OneContigSpaceCardGeneration::shrink_by(size_t bytes) { 769 assert_locked_or_safepoint(ExpandHeap_lock); 770 // Shrink committed space 771 _virtual_space.shrink_by(bytes); 772 // Shrink space; this also shrinks the space's BOT 773 _the_space->set_end((HeapWord*) _virtual_space.high()); 774 size_t new_word_size = heap_word_size(_the_space->capacity()); 775 // Shrink the shared block offset array 776 _bts->resize(new_word_size); 777 MemRegion mr(_the_space->bottom(), new_word_size); 778 // Shrink the card table 779 Universe::heap()->barrier_set()->resize_covered_region(mr); 780 781 if (Verbose && PrintGC) { 782 size_t new_mem_size = _virtual_space.committed_size(); 783 size_t old_mem_size = new_mem_size + bytes; 784 gclog_or_tty->print_cr("Shrinking %s from " SIZE_FORMAT "K to " SIZE_FORMAT "K", 785 name(), old_mem_size/K, new_mem_size/K); 786 } 787 } 788 789 // Currently nothing to do. 790 void OneContigSpaceCardGeneration::prepare_for_verify() {} 791 792 793 // Override for a card-table generation with one contiguous 794 // space. NOTE: For reasons that are lost in the fog of history, 795 // this code is used when you iterate over perm gen objects, 796 // even when one uses CDS, where the perm gen has a couple of 797 // other spaces; this is because CompactingPermGenGen derives 798 // from OneContigSpaceCardGeneration. This should be cleaned up, 799 // see CR 6897789.. 800 void OneContigSpaceCardGeneration::object_iterate(ObjectClosure* blk) { 801 _the_space->object_iterate(blk); 802 } 803 804 void OneContigSpaceCardGeneration::space_iterate(SpaceClosure* blk, 805 bool usedOnly) { 806 blk->do_space(_the_space); 807 } 808 809 void OneContigSpaceCardGeneration::younger_refs_iterate(OopsInGenClosure* blk) { 810 blk->set_generation(this); 811 younger_refs_in_space_iterate(_the_space, blk); 812 blk->reset_generation(); 813 } 814 815 void OneContigSpaceCardGeneration::save_marks() { 816 _the_space->set_saved_mark(); 817 } 818 819 820 void OneContigSpaceCardGeneration::reset_saved_marks() { 821 _the_space->reset_saved_mark(); 822 } 823 824 825 bool OneContigSpaceCardGeneration::no_allocs_since_save_marks() { 826 return _the_space->saved_mark_at_top(); 827 } 828 829 #define OneContig_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \ 830 \ 831 void OneContigSpaceCardGeneration:: \ 832 oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \ 833 blk->set_generation(this); \ 834 _the_space->oop_since_save_marks_iterate##nv_suffix(blk); \ 835 blk->reset_generation(); \ 836 save_marks(); \ 837 } 838 839 ALL_SINCE_SAVE_MARKS_CLOSURES(OneContig_SINCE_SAVE_MARKS_ITERATE_DEFN) 840 841 #undef OneContig_SINCE_SAVE_MARKS_ITERATE_DEFN 842 843 844 void OneContigSpaceCardGeneration::gc_epilogue(bool full) { 845 _last_gc = WaterMark(the_space(), the_space()->top()); 846 847 // update the generation and space performance counters 848 update_counters(); 849 if (ZapUnusedHeapArea) { 850 the_space()->check_mangled_unused_area_complete(); 851 } 852 } 853 854 void OneContigSpaceCardGeneration::record_spaces_top() { 855 assert(ZapUnusedHeapArea, "Not mangling unused space"); 856 the_space()->set_top_for_allocations(); 857 } 858 859 void OneContigSpaceCardGeneration::verify() { 860 the_space()->verify(); 861 } 862 863 void OneContigSpaceCardGeneration::print_on(outputStream* st) const { 864 Generation::print_on(st); 865 st->print(" the"); 866 the_space()->print_on(st); 867 }