1 /* 2 * Copyright (c) 1997, 2013, 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 Generation::Generation(ReservedSpace rs, size_t initial_size, int level) : 47 _level(level), 48 _ref_processor(NULL) { 49 if (!_virtual_space.initialize(rs, initial_size)) { 50 vm_exit_during_initialization("Could not reserve enough space for " 51 "object heap"); 52 } 53 // Mangle all of the the initial generation. 54 if (ZapUnusedHeapArea) { 55 MemRegion mangle_region((HeapWord*)_virtual_space.low(), 56 (HeapWord*)_virtual_space.high()); 57 SpaceMangler::mangle_region(mangle_region); 58 } 59 _reserved = MemRegion((HeapWord*)_virtual_space.low_boundary(), 60 (HeapWord*)_virtual_space.high_boundary()); 61 } 62 63 GenerationSpec* Generation::spec() { 64 GenCollectedHeap* gch = GenCollectedHeap::heap(); 65 assert(0 <= level() && level() < gch->_n_gens, "Bad gen level"); 66 return gch->_gen_specs[level()]; 67 } 68 69 size_t Generation::max_capacity() const { 70 return reserved().byte_size(); 71 } 72 73 void Generation::print_heap_change(size_t prev_used) const { 74 if (PrintGCDetails && Verbose) { 75 gclog_or_tty->print(" " SIZE_FORMAT 76 "->" SIZE_FORMAT 77 "(" SIZE_FORMAT ")", 78 prev_used, used(), capacity()); 79 } else { 80 gclog_or_tty->print(" " SIZE_FORMAT "K" 81 "->" SIZE_FORMAT "K" 82 "(" SIZE_FORMAT "K)", 83 prev_used / K, used() / K, capacity() / K); 84 } 85 } 86 87 // By default we get a single threaded default reference processor; 88 // generations needing multi-threaded refs processing or discovery override this method. 89 void Generation::ref_processor_init() { 90 assert(_ref_processor == NULL, "a reference processor already exists"); 91 assert(!_reserved.is_empty(), "empty generation?"); 92 _ref_processor = new ReferenceProcessor(_reserved); // a vanilla reference processor 93 if (_ref_processor == NULL) { 94 vm_exit_during_initialization("Could not allocate ReferenceProcessor object"); 95 } 96 } 97 98 void Generation::print() const { print_on(tty); } 99 100 void Generation::print_on(outputStream* st) const { 101 st->print(" %-20s", name()); 102 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 103 capacity()/K, used()/K); 104 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 105 _virtual_space.low_boundary(), 106 _virtual_space.high(), 107 _virtual_space.high_boundary()); 108 } 109 110 void Generation::print_summary_info() { print_summary_info_on(tty); } 111 112 void Generation::print_summary_info_on(outputStream* st) { 113 StatRecord* sr = stat_record(); 114 double time = sr->accumulated_time.seconds(); 115 st->print_cr("[Accumulated GC generation %d time %3.7f secs, " 116 "%d GC's, avg GC time %3.7f]", 117 level(), time, sr->invocations, 118 sr->invocations > 0 ? time / sr->invocations : 0.0); 119 } 120 121 // Utility iterator classes 122 123 class GenerationIsInReservedClosure : public SpaceClosure { 124 public: 125 const void* _p; 126 Space* sp; 127 virtual void do_space(Space* s) { 128 if (sp == NULL) { 129 if (s->is_in_reserved(_p)) sp = s; 130 } 131 } 132 GenerationIsInReservedClosure(const void* p) : _p(p), sp(NULL) {} 133 }; 134 135 class GenerationIsInClosure : public SpaceClosure { 136 public: 137 const void* _p; 138 Space* sp; 139 virtual void do_space(Space* s) { 140 if (sp == NULL) { 141 if (s->is_in(_p)) sp = s; 142 } 143 } 144 GenerationIsInClosure(const void* p) : _p(p), sp(NULL) {} 145 }; 146 147 bool Generation::is_in(const void* p) const { 148 GenerationIsInClosure blk(p); 149 ((Generation*)this)->space_iterate(&blk); 150 return blk.sp != NULL; 151 } 152 153 DefNewGeneration* Generation::as_DefNewGeneration() { 154 assert((kind() == Generation::DefNew) || 155 (kind() == Generation::ParNew) || 156 (kind() == Generation::ASParNew), 157 "Wrong youngest generation type"); 158 return (DefNewGeneration*) this; 159 } 160 161 Generation* Generation::next_gen() const { 162 GenCollectedHeap* gch = GenCollectedHeap::heap(); 163 int next = level() + 1; 164 if (next < gch->_n_gens) { 165 return gch->_gens[next]; 166 } else { 167 return NULL; 168 } 169 } 170 171 size_t Generation::max_contiguous_available() const { 172 // The largest number of contiguous free words in this or any higher generation. 173 size_t max = 0; 174 for (const Generation* gen = this; gen != NULL; gen = gen->next_gen()) { 175 size_t avail = gen->contiguous_available(); 176 if (avail > max) { 177 max = avail; 178 } 179 } 180 return max; 181 } 182 183 bool Generation::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const { 184 size_t available = max_contiguous_available(); 185 bool res = (available >= max_promotion_in_bytes); 186 if (PrintGC && Verbose) { 187 gclog_or_tty->print_cr( 188 "Generation: promo attempt is%s safe: available("SIZE_FORMAT") %s max_promo("SIZE_FORMAT")", 189 res? "":" not", available, res? ">=":"<", 190 max_promotion_in_bytes); 191 } 192 return res; 193 } 194 195 // Ignores "ref" and calls allocate(). 196 oop Generation::promote(oop obj, size_t obj_size) { 197 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); 198 199 #ifndef PRODUCT 200 if (Universe::heap()->promotion_should_fail()) { 201 return NULL; 202 } 203 #endif // #ifndef PRODUCT 204 205 HeapWord* result = allocate(obj_size, false); 206 if (result != NULL) { 207 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size); 208 return oop(result); 209 } else { 210 GenCollectedHeap* gch = GenCollectedHeap::heap(); 211 return gch->handle_failed_promotion(this, obj, obj_size); 212 } 213 } 214 215 oop Generation::par_promote(int thread_num, 216 oop obj, markOop m, size_t word_sz) { 217 // Could do a bad general impl here that gets a lock. But no. 218 ShouldNotCallThis(); 219 return NULL; 220 } 221 222 void Generation::par_promote_alloc_undo(int thread_num, 223 HeapWord* obj, size_t word_sz) { 224 // Could do a bad general impl here that gets a lock. But no. 225 guarantee(false, "No good general implementation."); 226 } 227 228 Space* Generation::space_containing(const void* p) const { 229 GenerationIsInReservedClosure blk(p); 230 // Cast away const 231 ((Generation*)this)->space_iterate(&blk); 232 return blk.sp; 233 } 234 235 // Some of these are mediocre general implementations. Should be 236 // overridden to get better performance. 237 238 class GenerationBlockStartClosure : public SpaceClosure { 239 public: 240 const void* _p; 241 HeapWord* _start; 242 virtual void do_space(Space* s) { 243 if (_start == NULL && s->is_in_reserved(_p)) { 244 _start = s->block_start(_p); 245 } 246 } 247 GenerationBlockStartClosure(const void* p) { _p = p; _start = NULL; } 248 }; 249 250 HeapWord* Generation::block_start(const void* p) const { 251 GenerationBlockStartClosure blk(p); 252 // Cast away const 253 ((Generation*)this)->space_iterate(&blk); 254 return blk._start; 255 } 256 257 class GenerationBlockSizeClosure : public SpaceClosure { 258 public: 259 const HeapWord* _p; 260 size_t size; 261 virtual void do_space(Space* s) { 262 if (size == 0 && s->is_in_reserved(_p)) { 263 size = s->block_size(_p); 264 } 265 } 266 GenerationBlockSizeClosure(const HeapWord* p) { _p = p; size = 0; } 267 }; 268 269 size_t Generation::block_size(const HeapWord* p) const { 270 GenerationBlockSizeClosure blk(p); 271 // Cast away const 272 ((Generation*)this)->space_iterate(&blk); 273 assert(blk.size > 0, "seems reasonable"); 274 return blk.size; 275 } 276 277 class GenerationBlockIsObjClosure : public SpaceClosure { 278 public: 279 const HeapWord* _p; 280 bool is_obj; 281 virtual void do_space(Space* s) { 282 if (!is_obj && s->is_in_reserved(_p)) { 283 is_obj |= s->block_is_obj(_p); 284 } 285 } 286 GenerationBlockIsObjClosure(const HeapWord* p) { _p = p; is_obj = false; } 287 }; 288 289 bool Generation::block_is_obj(const HeapWord* p) const { 290 GenerationBlockIsObjClosure blk(p); 291 // Cast away const 292 ((Generation*)this)->space_iterate(&blk); 293 return blk.is_obj; 294 } 295 296 class GenerationOopIterateClosure : public SpaceClosure { 297 public: 298 ExtendedOopClosure* cl; 299 MemRegion mr; 300 virtual void do_space(Space* s) { 301 s->oop_iterate(mr, cl); 302 } 303 GenerationOopIterateClosure(ExtendedOopClosure* _cl, MemRegion _mr) : 304 cl(_cl), mr(_mr) {} 305 }; 306 307 void Generation::oop_iterate(ExtendedOopClosure* cl) { 308 GenerationOopIterateClosure blk(cl, _reserved); 309 space_iterate(&blk); 310 } 311 312 void Generation::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) { 313 GenerationOopIterateClosure blk(cl, mr); 314 space_iterate(&blk); 315 } 316 317 void Generation::younger_refs_in_space_iterate(Space* sp, 318 OopsInGenClosure* cl) { 319 GenRemSet* rs = SharedHeap::heap()->rem_set(); 320 rs->younger_refs_in_space_iterate(sp, cl); 321 } 322 323 class GenerationObjIterateClosure : public SpaceClosure { 324 private: 325 ObjectClosure* _cl; 326 public: 327 virtual void do_space(Space* s) { 328 s->object_iterate(_cl); 329 } 330 GenerationObjIterateClosure(ObjectClosure* cl) : _cl(cl) {} 331 }; 332 333 void Generation::object_iterate(ObjectClosure* cl) { 334 GenerationObjIterateClosure blk(cl); 335 space_iterate(&blk); 336 } 337 338 class GenerationSafeObjIterateClosure : public SpaceClosure { 339 private: 340 ObjectClosure* _cl; 341 public: 342 virtual void do_space(Space* s) { 343 s->safe_object_iterate(_cl); 344 } 345 GenerationSafeObjIterateClosure(ObjectClosure* cl) : _cl(cl) {} 346 }; 347 348 void Generation::safe_object_iterate(ObjectClosure* cl) { 349 GenerationSafeObjIterateClosure blk(cl); 350 space_iterate(&blk); 351 } 352 353 void Generation::prepare_for_compaction(CompactPoint* cp) { 354 // Generic implementation, can be specialized 355 CompactibleSpace* space = first_compaction_space(); 356 while (space != NULL) { 357 space->prepare_for_compaction(cp); 358 space = space->next_compaction_space(); 359 } 360 } 361 362 class AdjustPointersClosure: public SpaceClosure { 363 public: 364 void do_space(Space* sp) { 365 sp->adjust_pointers(); 366 } 367 }; 368 369 void Generation::adjust_pointers() { 370 // Note that this is done over all spaces, not just the compactible 371 // ones. 372 AdjustPointersClosure blk; 373 space_iterate(&blk, true); 374 } 375 376 void Generation::compact() { 377 CompactibleSpace* sp = first_compaction_space(); 378 while (sp != NULL) { 379 sp->compact(); 380 sp = sp->next_compaction_space(); 381 } 382 } 383 384 CardGeneration::CardGeneration(ReservedSpace rs, size_t initial_byte_size, 385 int level, 386 GenRemSet* remset) : 387 Generation(rs, initial_byte_size, level), _rs(remset), 388 _shrink_factor(0), _min_heap_delta_bytes(), _capacity_at_prologue(), 389 _used_at_prologue() 390 { 391 HeapWord* start = (HeapWord*)rs.base(); 392 size_t reserved_byte_size = rs.size(); 393 assert((uintptr_t(start) & 3) == 0, "bad alignment"); 394 assert((reserved_byte_size & 3) == 0, "bad alignment"); 395 MemRegion reserved_mr(start, heap_word_size(reserved_byte_size)); 396 _bts = new BlockOffsetSharedArray(reserved_mr, 397 heap_word_size(initial_byte_size)); 398 MemRegion committed_mr(start, heap_word_size(initial_byte_size)); 399 _rs->resize_covered_region(committed_mr); 400 if (_bts == NULL) 401 vm_exit_during_initialization("Could not allocate a BlockOffsetArray"); 402 403 // Verify that the start and end of this generation is the start of a card. 404 // If this wasn't true, a single card could span more than on generation, 405 // which would cause problems when we commit/uncommit memory, and when we 406 // clear and dirty cards. 407 guarantee(_rs->is_aligned(reserved_mr.start()), "generation must be card aligned"); 408 if (reserved_mr.end() != Universe::heap()->reserved_region().end()) { 409 // Don't check at the very end of the heap as we'll assert that we're probing off 410 // the end if we try. 411 guarantee(_rs->is_aligned(reserved_mr.end()), "generation must be card aligned"); 412 } 413 _min_heap_delta_bytes = MinHeapDeltaBytes; 414 _capacity_at_prologue = initial_byte_size; 415 _used_at_prologue = 0; 416 } 417 418 bool CardGeneration::expand(size_t bytes, size_t expand_bytes) { 419 assert_locked_or_safepoint(Heap_lock); 420 if (bytes == 0) { 421 return true; // That's what grow_by(0) would return 422 } 423 size_t aligned_bytes = ReservedSpace::page_align_size_up(bytes); 424 if (aligned_bytes == 0){ 425 // The alignment caused the number of bytes to wrap. An expand_by(0) will 426 // return true with the implication that an expansion was done when it 427 // was not. A call to expand implies a best effort to expand by "bytes" 428 // but not a guarantee. Align down to give a best effort. This is likely 429 // the most that the generation can expand since it has some capacity to 430 // start with. 431 aligned_bytes = ReservedSpace::page_align_size_down(bytes); 432 } 433 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 434 bool success = false; 435 if (aligned_expand_bytes > aligned_bytes) { 436 success = grow_by(aligned_expand_bytes); 437 } 438 if (!success) { 439 success = grow_by(aligned_bytes); 440 } 441 if (!success) { 442 success = grow_to_reserved(); 443 } 444 if (PrintGC && Verbose) { 445 if (success && GC_locker::is_active_and_needs_gc()) { 446 gclog_or_tty->print_cr("Garbage collection disabled, expanded heap instead"); 447 } 448 } 449 450 return success; 451 } 452 453 454 // No young generation references, clear this generation's cards. 455 void CardGeneration::clear_remembered_set() { 456 _rs->clear(reserved()); 457 } 458 459 460 // Objects in this generation may have moved, invalidate this 461 // generation's cards. 462 void CardGeneration::invalidate_remembered_set() { 463 _rs->invalidate(used_region()); 464 } 465 466 467 void CardGeneration::compute_new_size() { 468 assert(_shrink_factor <= 100, "invalid shrink factor"); 469 size_t current_shrink_factor = _shrink_factor; 470 _shrink_factor = 0; 471 472 // We don't have floating point command-line arguments 473 // Note: argument processing ensures that MinHeapFreeRatio < 100. 474 const double minimum_free_percentage = MinHeapFreeRatio / 100.0; 475 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 476 477 // Compute some numbers about the state of the heap. 478 const size_t used_after_gc = used(); 479 const size_t capacity_after_gc = capacity(); 480 481 const double min_tmp = used_after_gc / maximum_used_percentage; 482 size_t minimum_desired_capacity = (size_t)MIN2(min_tmp, double(max_uintx)); 483 // Don't shrink less than the initial generation size 484 minimum_desired_capacity = MAX2(minimum_desired_capacity, 485 spec()->init_size()); 486 assert(used_after_gc <= minimum_desired_capacity, "sanity check"); 487 488 if (PrintGC && Verbose) { 489 const size_t free_after_gc = free(); 490 const double free_percentage = ((double)free_after_gc) / capacity_after_gc; 491 gclog_or_tty->print_cr("TenuredGeneration::compute_new_size: "); 492 gclog_or_tty->print_cr(" " 493 " minimum_free_percentage: %6.2f" 494 " maximum_used_percentage: %6.2f", 495 minimum_free_percentage, 496 maximum_used_percentage); 497 gclog_or_tty->print_cr(" " 498 " free_after_gc : %6.1fK" 499 " used_after_gc : %6.1fK" 500 " capacity_after_gc : %6.1fK", 501 free_after_gc / (double) K, 502 used_after_gc / (double) K, 503 capacity_after_gc / (double) K); 504 gclog_or_tty->print_cr(" " 505 " free_percentage: %6.2f", 506 free_percentage); 507 } 508 509 if (capacity_after_gc < minimum_desired_capacity) { 510 // If we have less free space than we want then expand 511 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 512 // Don't expand unless it's significant 513 if (expand_bytes >= _min_heap_delta_bytes) { 514 expand(expand_bytes, 0); // safe if expansion fails 515 } 516 if (PrintGC && Verbose) { 517 gclog_or_tty->print_cr(" expanding:" 518 " minimum_desired_capacity: %6.1fK" 519 " expand_bytes: %6.1fK" 520 " _min_heap_delta_bytes: %6.1fK", 521 minimum_desired_capacity / (double) K, 522 expand_bytes / (double) K, 523 _min_heap_delta_bytes / (double) K); 524 } 525 return; 526 } 527 528 // No expansion, now see if we want to shrink 529 size_t shrink_bytes = 0; 530 // We would never want to shrink more than this 531 size_t max_shrink_bytes = capacity_after_gc - minimum_desired_capacity; 532 533 if (MaxHeapFreeRatio < 100) { 534 const double maximum_free_percentage = MaxHeapFreeRatio / 100.0; 535 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 536 const double max_tmp = used_after_gc / minimum_used_percentage; 537 size_t maximum_desired_capacity = (size_t)MIN2(max_tmp, double(max_uintx)); 538 maximum_desired_capacity = MAX2(maximum_desired_capacity, 539 spec()->init_size()); 540 if (PrintGC && Verbose) { 541 gclog_or_tty->print_cr(" " 542 " maximum_free_percentage: %6.2f" 543 " minimum_used_percentage: %6.2f", 544 maximum_free_percentage, 545 minimum_used_percentage); 546 gclog_or_tty->print_cr(" " 547 " _capacity_at_prologue: %6.1fK" 548 " minimum_desired_capacity: %6.1fK" 549 " maximum_desired_capacity: %6.1fK", 550 _capacity_at_prologue / (double) K, 551 minimum_desired_capacity / (double) K, 552 maximum_desired_capacity / (double) K); 553 } 554 assert(minimum_desired_capacity <= maximum_desired_capacity, 555 "sanity check"); 556 557 if (capacity_after_gc > maximum_desired_capacity) { 558 // Capacity too large, compute shrinking size 559 shrink_bytes = capacity_after_gc - maximum_desired_capacity; 560 // We don't want shrink all the way back to initSize if people call 561 // System.gc(), because some programs do that between "phases" and then 562 // we'd just have to grow the heap up again for the next phase. So we 563 // damp the shrinking: 0% on the first call, 10% on the second call, 40% 564 // on the third call, and 100% by the fourth call. But if we recompute 565 // size without shrinking, it goes back to 0%. 566 shrink_bytes = shrink_bytes / 100 * current_shrink_factor; 567 assert(shrink_bytes <= max_shrink_bytes, "invalid shrink size"); 568 if (current_shrink_factor == 0) { 569 _shrink_factor = 10; 570 } else { 571 _shrink_factor = MIN2(current_shrink_factor * 4, (size_t) 100); 572 } 573 if (PrintGC && Verbose) { 574 gclog_or_tty->print_cr(" " 575 " shrinking:" 576 " initSize: %.1fK" 577 " maximum_desired_capacity: %.1fK", 578 spec()->init_size() / (double) K, 579 maximum_desired_capacity / (double) K); 580 gclog_or_tty->print_cr(" " 581 " shrink_bytes: %.1fK" 582 " current_shrink_factor: %d" 583 " new shrink factor: %d" 584 " _min_heap_delta_bytes: %.1fK", 585 shrink_bytes / (double) K, 586 current_shrink_factor, 587 _shrink_factor, 588 _min_heap_delta_bytes / (double) K); 589 } 590 } 591 } 592 593 if (capacity_after_gc > _capacity_at_prologue) { 594 // We might have expanded for promotions, in which case we might want to 595 // take back that expansion if there's room after GC. That keeps us from 596 // stretching the heap with promotions when there's plenty of room. 597 size_t expansion_for_promotion = capacity_after_gc - _capacity_at_prologue; 598 expansion_for_promotion = MIN2(expansion_for_promotion, max_shrink_bytes); 599 // We have two shrinking computations, take the largest 600 shrink_bytes = MAX2(shrink_bytes, expansion_for_promotion); 601 assert(shrink_bytes <= max_shrink_bytes, "invalid shrink size"); 602 if (PrintGC && Verbose) { 603 gclog_or_tty->print_cr(" " 604 " aggressive shrinking:" 605 " _capacity_at_prologue: %.1fK" 606 " capacity_after_gc: %.1fK" 607 " expansion_for_promotion: %.1fK" 608 " shrink_bytes: %.1fK", 609 capacity_after_gc / (double) K, 610 _capacity_at_prologue / (double) K, 611 expansion_for_promotion / (double) K, 612 shrink_bytes / (double) K); 613 } 614 } 615 // Don't shrink unless it's significant 616 if (shrink_bytes >= _min_heap_delta_bytes) { 617 shrink(shrink_bytes); 618 } 619 } 620 621 // Currently nothing to do. 622 void CardGeneration::prepare_for_verify() {} 623 624 625 void OneContigSpaceCardGeneration::collect(bool full, 626 bool clear_all_soft_refs, 627 size_t size, 628 bool is_tlab) { 629 GenCollectedHeap* gch = GenCollectedHeap::heap(); 630 631 SpecializationStats::clear(); 632 // Temporarily expand the span of our ref processor, so 633 // refs discovery is over the entire heap, not just this generation 634 ReferenceProcessorSpanMutator 635 x(ref_processor(), gch->reserved_region()); 636 637 STWGCTimer* gc_timer = GenMarkSweep::gc_timer(); 638 gc_timer->register_gc_start(); 639 640 SerialOldTracer* gc_tracer = GenMarkSweep::gc_tracer(); 641 gc_tracer->report_gc_start(gch->gc_cause(), gc_timer->gc_start()); 642 643 GenMarkSweep::invoke_at_safepoint(_level, ref_processor(), clear_all_soft_refs); 644 645 gc_timer->register_gc_end(); 646 647 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 648 649 SpecializationStats::print(); 650 } 651 652 HeapWord* 653 OneContigSpaceCardGeneration::expand_and_allocate(size_t word_size, 654 bool is_tlab, 655 bool parallel) { 656 assert(!is_tlab, "OneContigSpaceCardGeneration does not support TLAB allocation"); 657 if (parallel) { 658 MutexLocker x(ParGCRareEvent_lock); 659 HeapWord* result = NULL; 660 size_t byte_size = word_size * HeapWordSize; 661 while (true) { 662 expand(byte_size, _min_heap_delta_bytes); 663 if (GCExpandToAllocateDelayMillis > 0) { 664 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); 665 } 666 result = _the_space->par_allocate(word_size); 667 if ( result != NULL) { 668 return result; 669 } else { 670 // If there's not enough expansion space available, give up. 671 if (_virtual_space.uncommitted_size() < byte_size) { 672 return NULL; 673 } 674 // else try again 675 } 676 } 677 } else { 678 expand(word_size*HeapWordSize, _min_heap_delta_bytes); 679 return _the_space->allocate(word_size); 680 } 681 } 682 683 bool OneContigSpaceCardGeneration::expand(size_t bytes, size_t expand_bytes) { 684 GCMutexLocker x(ExpandHeap_lock); 685 return CardGeneration::expand(bytes, expand_bytes); 686 } 687 688 689 void OneContigSpaceCardGeneration::shrink(size_t bytes) { 690 assert_locked_or_safepoint(ExpandHeap_lock); 691 size_t size = ReservedSpace::page_align_size_down(bytes); 692 if (size > 0) { 693 shrink_by(size); 694 } 695 } 696 697 698 size_t OneContigSpaceCardGeneration::capacity() const { 699 return _the_space->capacity(); 700 } 701 702 703 size_t OneContigSpaceCardGeneration::used() const { 704 return _the_space->used(); 705 } 706 707 708 size_t OneContigSpaceCardGeneration::free() const { 709 return _the_space->free(); 710 } 711 712 MemRegion OneContigSpaceCardGeneration::used_region() const { 713 return the_space()->used_region(); 714 } 715 716 size_t OneContigSpaceCardGeneration::unsafe_max_alloc_nogc() const { 717 return _the_space->free(); 718 } 719 720 size_t OneContigSpaceCardGeneration::contiguous_available() const { 721 return _the_space->free() + _virtual_space.uncommitted_size(); 722 } 723 724 bool OneContigSpaceCardGeneration::grow_by(size_t bytes) { 725 assert_locked_or_safepoint(ExpandHeap_lock); 726 bool result = _virtual_space.expand_by(bytes); 727 if (result) { 728 size_t new_word_size = 729 heap_word_size(_virtual_space.committed_size()); 730 MemRegion mr(_the_space->bottom(), new_word_size); 731 // Expand card table 732 Universe::heap()->barrier_set()->resize_covered_region(mr); 733 // Expand shared block offset array 734 _bts->resize(new_word_size); 735 736 // Fix for bug #4668531 737 if (ZapUnusedHeapArea) { 738 MemRegion mangle_region(_the_space->end(), 739 (HeapWord*)_virtual_space.high()); 740 SpaceMangler::mangle_region(mangle_region); 741 } 742 743 // Expand space -- also expands space's BOT 744 // (which uses (part of) shared array above) 745 _the_space->set_end((HeapWord*)_virtual_space.high()); 746 747 // update the space and generation capacity counters 748 update_counters(); 749 750 if (Verbose && PrintGC) { 751 size_t new_mem_size = _virtual_space.committed_size(); 752 size_t old_mem_size = new_mem_size - bytes; 753 gclog_or_tty->print_cr("Expanding %s from " SIZE_FORMAT "K by " 754 SIZE_FORMAT "K to " SIZE_FORMAT "K", 755 name(), old_mem_size/K, bytes/K, new_mem_size/K); 756 } 757 } 758 return result; 759 } 760 761 762 bool OneContigSpaceCardGeneration::grow_to_reserved() { 763 assert_locked_or_safepoint(ExpandHeap_lock); 764 bool success = true; 765 const size_t remaining_bytes = _virtual_space.uncommitted_size(); 766 if (remaining_bytes > 0) { 767 success = grow_by(remaining_bytes); 768 DEBUG_ONLY(if (!success) warning("grow to reserved failed");) 769 } 770 return success; 771 } 772 773 void OneContigSpaceCardGeneration::shrink_by(size_t bytes) { 774 assert_locked_or_safepoint(ExpandHeap_lock); 775 // Shrink committed space 776 _virtual_space.shrink_by(bytes); 777 // Shrink space; this also shrinks the space's BOT 778 _the_space->set_end((HeapWord*) _virtual_space.high()); 779 size_t new_word_size = heap_word_size(_the_space->capacity()); 780 // Shrink the shared block offset array 781 _bts->resize(new_word_size); 782 MemRegion mr(_the_space->bottom(), new_word_size); 783 // Shrink the card table 784 Universe::heap()->barrier_set()->resize_covered_region(mr); 785 786 if (Verbose && PrintGC) { 787 size_t new_mem_size = _virtual_space.committed_size(); 788 size_t old_mem_size = new_mem_size + bytes; 789 gclog_or_tty->print_cr("Shrinking %s from " SIZE_FORMAT "K to " SIZE_FORMAT "K", 790 name(), old_mem_size/K, new_mem_size/K); 791 } 792 } 793 794 // Currently nothing to do. 795 void OneContigSpaceCardGeneration::prepare_for_verify() {} 796 797 798 // Override for a card-table generation with one contiguous 799 // space. NOTE: For reasons that are lost in the fog of history, 800 // this code is used when you iterate over perm gen objects, 801 // even when one uses CDS, where the perm gen has a couple of 802 // other spaces; this is because CompactingPermGenGen derives 803 // from OneContigSpaceCardGeneration. This should be cleaned up, 804 // see CR 6897789.. 805 void OneContigSpaceCardGeneration::object_iterate(ObjectClosure* blk) { 806 _the_space->object_iterate(blk); 807 } 808 809 void OneContigSpaceCardGeneration::space_iterate(SpaceClosure* blk, 810 bool usedOnly) { 811 blk->do_space(_the_space); 812 } 813 814 void OneContigSpaceCardGeneration::younger_refs_iterate(OopsInGenClosure* blk) { 815 blk->set_generation(this); 816 younger_refs_in_space_iterate(_the_space, blk); 817 blk->reset_generation(); 818 } 819 820 void OneContigSpaceCardGeneration::save_marks() { 821 _the_space->set_saved_mark(); 822 } 823 824 825 void OneContigSpaceCardGeneration::reset_saved_marks() { 826 _the_space->reset_saved_mark(); 827 } 828 829 830 bool OneContigSpaceCardGeneration::no_allocs_since_save_marks() { 831 return _the_space->saved_mark_at_top(); 832 } 833 834 #define OneContig_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \ 835 \ 836 void OneContigSpaceCardGeneration:: \ 837 oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \ 838 blk->set_generation(this); \ 839 _the_space->oop_since_save_marks_iterate##nv_suffix(blk); \ 840 blk->reset_generation(); \ 841 save_marks(); \ 842 } 843 844 ALL_SINCE_SAVE_MARKS_CLOSURES(OneContig_SINCE_SAVE_MARKS_ITERATE_DEFN) 845 846 #undef OneContig_SINCE_SAVE_MARKS_ITERATE_DEFN 847 848 849 void OneContigSpaceCardGeneration::gc_epilogue(bool full) { 850 _last_gc = WaterMark(the_space(), the_space()->top()); 851 852 // update the generation and space performance counters 853 update_counters(); 854 if (ZapUnusedHeapArea) { 855 the_space()->check_mangled_unused_area_complete(); 856 } 857 } 858 859 void OneContigSpaceCardGeneration::record_spaces_top() { 860 assert(ZapUnusedHeapArea, "Not mangling unused space"); 861 the_space()->set_top_for_allocations(); 862 } 863 864 void OneContigSpaceCardGeneration::verify() { 865 the_space()->verify(); 866 } 867 868 void OneContigSpaceCardGeneration::print_on(outputStream* st) const { 869 Generation::print_on(st); 870 st->print(" the"); 871 the_space()->print_on(st); 872 }