1 /* 2 * Copyright (c) 2005, 2019, 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 #ifndef SHARE_GC_PARALLEL_PSPARALLELCOMPACT_HPP 26 #define SHARE_GC_PARALLEL_PSPARALLELCOMPACT_HPP 27 28 #include "gc/parallel/mutableSpace.hpp" 29 #include "gc/parallel/objectStartArray.hpp" 30 #include "gc/parallel/parMarkBitMap.hpp" 31 #include "gc/parallel/parallelScavengeHeap.hpp" 32 #include "gc/shared/collectedHeap.hpp" 33 #include "gc/shared/collectorCounters.hpp" 34 #include "oops/oop.hpp" 35 36 class ParallelScavengeHeap; 37 class PSAdaptiveSizePolicy; 38 class PSYoungGen; 39 class PSOldGen; 40 class ParCompactionManager; 41 class ParallelTaskTerminator; 42 class PSParallelCompact; 43 class PreGCValues; 44 class MoveAndUpdateClosure; 45 class RefProcTaskExecutor; 46 class ParallelOldTracer; 47 class STWGCTimer; 48 49 // The SplitInfo class holds the information needed to 'split' a source region 50 // so that the live data can be copied to two destination *spaces*. Normally, 51 // all the live data in a region is copied to a single destination space (e.g., 52 // everything live in a region in eden is copied entirely into the old gen). 53 // However, when the heap is nearly full, all the live data in eden may not fit 54 // into the old gen. Copying only some of the regions from eden to old gen 55 // requires finding a region that does not contain a partial object (i.e., no 56 // live object crosses the region boundary) somewhere near the last object that 57 // does fit into the old gen. Since it's not always possible to find such a 58 // region, splitting is necessary for predictable behavior. 59 // 60 // A region is always split at the end of the partial object. This avoids 61 // additional tests when calculating the new location of a pointer, which is a 62 // very hot code path. The partial object and everything to its left will be 63 // copied to another space (call it dest_space_1). The live data to the right 64 // of the partial object will be copied either within the space itself, or to a 65 // different destination space (distinct from dest_space_1). 66 // 67 // Split points are identified during the summary phase, when region 68 // destinations are computed: data about the split, including the 69 // partial_object_size, is recorded in a SplitInfo record and the 70 // partial_object_size field in the summary data is set to zero. The zeroing is 71 // possible (and necessary) since the partial object will move to a different 72 // destination space than anything to its right, thus the partial object should 73 // not affect the locations of any objects to its right. 74 // 75 // The recorded data is used during the compaction phase, but only rarely: when 76 // the partial object on the split region will be copied across a destination 77 // region boundary. This test is made once each time a region is filled, and is 78 // a simple address comparison, so the overhead is negligible (see 79 // PSParallelCompact::first_src_addr()). 80 // 81 // Notes: 82 // 83 // Only regions with partial objects are split; a region without a partial 84 // object does not need any extra bookkeeping. 85 // 86 // At most one region is split per space, so the amount of data required is 87 // constant. 88 // 89 // A region is split only when the destination space would overflow. Once that 90 // happens, the destination space is abandoned and no other data (even from 91 // other source spaces) is targeted to that destination space. Abandoning the 92 // destination space may leave a somewhat large unused area at the end, if a 93 // large object caused the overflow. 94 // 95 // Future work: 96 // 97 // More bookkeeping would be required to continue to use the destination space. 98 // The most general solution would allow data from regions in two different 99 // source spaces to be "joined" in a single destination region. At the very 100 // least, additional code would be required in next_src_region() to detect the 101 // join and skip to an out-of-order source region. If the join region was also 102 // the last destination region to which a split region was copied (the most 103 // likely case), then additional work would be needed to get fill_region() to 104 // stop iteration and switch to a new source region at the right point. Basic 105 // idea would be to use a fake value for the top of the source space. It is 106 // doable, if a bit tricky. 107 // 108 // A simpler (but less general) solution would fill the remainder of the 109 // destination region with a dummy object and continue filling the next 110 // destination region. 111 112 class SplitInfo 113 { 114 public: 115 // Return true if this split info is valid (i.e., if a split has been 116 // recorded). The very first region cannot have a partial object and thus is 117 // never split, so 0 is the 'invalid' value. 118 bool is_valid() const { return _src_region_idx > 0; } 119 120 // Return true if this split holds data for the specified source region. 121 inline bool is_split(size_t source_region) const; 122 123 // The index of the split region, the size of the partial object on that 124 // region and the destination of the partial object. 125 size_t src_region_idx() const { return _src_region_idx; } 126 size_t partial_obj_size() const { return _partial_obj_size; } 127 HeapWord* destination() const { return _destination; } 128 129 // The destination count of the partial object referenced by this split 130 // (either 1 or 2). This must be added to the destination count of the 131 // remainder of the source region. 132 unsigned int destination_count() const { return _destination_count; } 133 134 // If a word within the partial object will be written to the first word of a 135 // destination region, this is the address of the destination region; 136 // otherwise this is NULL. 137 HeapWord* dest_region_addr() const { return _dest_region_addr; } 138 139 // If a word within the partial object will be written to the first word of a 140 // destination region, this is the address of that word within the partial 141 // object; otherwise this is NULL. 142 HeapWord* first_src_addr() const { return _first_src_addr; } 143 144 // Record the data necessary to split the region src_region_idx. 145 void record(size_t src_region_idx, size_t partial_obj_size, 146 HeapWord* destination); 147 148 void clear(); 149 150 DEBUG_ONLY(void verify_clear();) 151 152 private: 153 size_t _src_region_idx; 154 size_t _partial_obj_size; 155 HeapWord* _destination; 156 unsigned int _destination_count; 157 HeapWord* _dest_region_addr; 158 HeapWord* _first_src_addr; 159 }; 160 161 inline bool SplitInfo::is_split(size_t region_idx) const 162 { 163 return _src_region_idx == region_idx && is_valid(); 164 } 165 166 class SpaceInfo 167 { 168 public: 169 MutableSpace* space() const { return _space; } 170 171 // Where the free space will start after the collection. Valid only after the 172 // summary phase completes. 173 HeapWord* new_top() const { return _new_top; } 174 175 // Allows new_top to be set. 176 HeapWord** new_top_addr() { return &_new_top; } 177 178 // Where the smallest allowable dense prefix ends (used only for perm gen). 179 HeapWord* min_dense_prefix() const { return _min_dense_prefix; } 180 181 // Where the dense prefix ends, or the compacted region begins. 182 HeapWord* dense_prefix() const { return _dense_prefix; } 183 184 // The start array for the (generation containing the) space, or NULL if there 185 // is no start array. 186 ObjectStartArray* start_array() const { return _start_array; } 187 188 SplitInfo& split_info() { return _split_info; } 189 190 void set_space(MutableSpace* s) { _space = s; } 191 void set_new_top(HeapWord* addr) { _new_top = addr; } 192 void set_min_dense_prefix(HeapWord* addr) { _min_dense_prefix = addr; } 193 void set_dense_prefix(HeapWord* addr) { _dense_prefix = addr; } 194 void set_start_array(ObjectStartArray* s) { _start_array = s; } 195 196 void publish_new_top() const { _space->set_top(_new_top); } 197 198 private: 199 MutableSpace* _space; 200 HeapWord* _new_top; 201 HeapWord* _min_dense_prefix; 202 HeapWord* _dense_prefix; 203 ObjectStartArray* _start_array; 204 SplitInfo _split_info; 205 }; 206 207 class ParallelCompactData 208 { 209 public: 210 // Sizes are in HeapWords, unless indicated otherwise. 211 static const size_t Log2RegionSize; 212 static const size_t RegionSize; 213 static const size_t RegionSizeBytes; 214 215 // Mask for the bits in a size_t to get an offset within a region. 216 static const size_t RegionSizeOffsetMask; 217 // Mask for the bits in a pointer to get an offset within a region. 218 static const size_t RegionAddrOffsetMask; 219 // Mask for the bits in a pointer to get the address of the start of a region. 220 static const size_t RegionAddrMask; 221 222 static const size_t Log2BlockSize; 223 static const size_t BlockSize; 224 static const size_t BlockSizeBytes; 225 226 static const size_t BlockSizeOffsetMask; 227 static const size_t BlockAddrOffsetMask; 228 static const size_t BlockAddrMask; 229 230 static const size_t BlocksPerRegion; 231 static const size_t Log2BlocksPerRegion; 232 233 class RegionData 234 { 235 public: 236 // Destination address of the region. 237 HeapWord* destination() const { return _destination; } 238 239 // The first region containing data destined for this region. 240 size_t source_region() const { return _source_region; } 241 242 // The object (if any) starting in this region and ending in a different 243 // region that could not be updated during the main (parallel) compaction 244 // phase. This is different from _partial_obj_addr, which is an object that 245 // extends onto a source region. However, the two uses do not overlap in 246 // time, so the same field is used to save space. 247 HeapWord* deferred_obj_addr() const { return _partial_obj_addr; } 248 249 // The starting address of the partial object extending onto the region. 250 HeapWord* partial_obj_addr() const { return _partial_obj_addr; } 251 252 // Size of the partial object extending onto the region (words). 253 size_t partial_obj_size() const { return _partial_obj_size; } 254 255 // Size of live data that lies within this region due to objects that start 256 // in this region (words). This does not include the partial object 257 // extending onto the region (if any), or the part of an object that extends 258 // onto the next region (if any). 259 size_t live_obj_size() const { return _dc_and_los & los_mask; } 260 261 // Total live data that lies within the region (words). 262 size_t data_size() const { return partial_obj_size() + live_obj_size(); } 263 264 // The destination_count is the number of other regions to which data from 265 // this region will be copied. At the end of the summary phase, the valid 266 // values of destination_count are 267 // 268 // 0 - data from the region will be compacted completely into itself, or the 269 // region is empty. The region can be claimed and then filled. 270 // 1 - data from the region will be compacted into 1 other region; some 271 // data from the region may also be compacted into the region itself. 272 // 2 - data from the region will be copied to 2 other regions. 273 // 274 // During compaction as regions are emptied, the destination_count is 275 // decremented (atomically) and when it reaches 0, it can be claimed and 276 // then filled. 277 // 278 // A region is claimed for processing by atomically changing the 279 // destination_count to the claimed value (dc_claimed). After a region has 280 // been filled, the destination_count should be set to the completed value 281 // (dc_completed). 282 inline uint destination_count() const; 283 inline uint destination_count_raw() const; 284 285 // Whether the block table for this region has been filled. 286 inline bool blocks_filled() const; 287 288 // Number of times the block table was filled. 289 DEBUG_ONLY(inline size_t blocks_filled_count() const;) 290 291 // The location of the java heap data that corresponds to this region. 292 inline HeapWord* data_location() const; 293 294 // The highest address referenced by objects in this region. 295 inline HeapWord* highest_ref() const; 296 297 // Whether this region is available to be claimed, has been claimed, or has 298 // been completed. 299 // 300 // Minor subtlety: claimed() returns true if the region is marked 301 // completed(), which is desirable since a region must be claimed before it 302 // can be completed. 303 bool available() const { return _dc_and_los < dc_one; } 304 bool claimed() const { return _dc_and_los >= dc_claimed; } 305 bool completed() const { return _dc_and_los >= dc_completed; } 306 307 // These are not atomic. 308 void set_destination(HeapWord* addr) { _destination = addr; } 309 void set_source_region(size_t region) { _source_region = region; } 310 void set_deferred_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; } 311 void set_partial_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; } 312 void set_partial_obj_size(size_t words) { 313 _partial_obj_size = (region_sz_t) words; 314 } 315 inline void set_blocks_filled(); 316 317 inline void set_destination_count(uint count); 318 inline void set_live_obj_size(size_t words); 319 inline void set_data_location(HeapWord* addr); 320 inline void set_completed(); 321 inline bool claim_unsafe(); 322 323 // These are atomic. 324 inline void add_live_obj(size_t words); 325 inline void set_highest_ref(HeapWord* addr); 326 inline void decrement_destination_count(); 327 inline bool claim(); 328 329 private: 330 // The type used to represent object sizes within a region. 331 typedef uint region_sz_t; 332 333 // Constants for manipulating the _dc_and_los field, which holds both the 334 // destination count and live obj size. The live obj size lives at the 335 // least significant end so no masking is necessary when adding. 336 static const region_sz_t dc_shift; // Shift amount. 337 static const region_sz_t dc_mask; // Mask for destination count. 338 static const region_sz_t dc_one; // 1, shifted appropriately. 339 static const region_sz_t dc_claimed; // Region has been claimed. 340 static const region_sz_t dc_completed; // Region has been completed. 341 static const region_sz_t los_mask; // Mask for live obj size. 342 343 HeapWord* _destination; 344 size_t _source_region; 345 HeapWord* _partial_obj_addr; 346 region_sz_t _partial_obj_size; 347 region_sz_t volatile _dc_and_los; 348 bool volatile _blocks_filled; 349 350 #ifdef ASSERT 351 size_t _blocks_filled_count; // Number of block table fills. 352 353 // These enable optimizations that are only partially implemented. Use 354 // debug builds to prevent the code fragments from breaking. 355 HeapWord* _data_location; 356 HeapWord* _highest_ref; 357 #endif // #ifdef ASSERT 358 359 #ifdef ASSERT 360 public: 361 uint _pushed; // 0 until region is pushed onto a stack 362 private: 363 #endif 364 }; 365 366 // "Blocks" allow shorter sections of the bitmap to be searched. Each Block 367 // holds an offset, which is the amount of live data in the Region to the left 368 // of the first live object that starts in the Block. 369 class BlockData 370 { 371 public: 372 typedef unsigned short int blk_ofs_t; 373 374 blk_ofs_t offset() const { return _offset; } 375 void set_offset(size_t val) { _offset = (blk_ofs_t)val; } 376 377 private: 378 blk_ofs_t _offset; 379 }; 380 381 public: 382 ParallelCompactData(); 383 bool initialize(MemRegion covered_region); 384 385 size_t region_count() const { return _region_count; } 386 size_t reserved_byte_size() const { return _reserved_byte_size; } 387 388 // Convert region indices to/from RegionData pointers. 389 inline RegionData* region(size_t region_idx) const; 390 inline size_t region(const RegionData* const region_ptr) const; 391 392 size_t block_count() const { return _block_count; } 393 inline BlockData* block(size_t block_idx) const; 394 inline size_t block(const BlockData* block_ptr) const; 395 396 void add_obj(HeapWord* addr, size_t len); 397 void add_obj(oop p, size_t len) { add_obj((HeapWord*)p, len); } 398 399 // Fill in the regions covering [beg, end) so that no data moves; i.e., the 400 // destination of region n is simply the start of region n. The argument beg 401 // must be region-aligned; end need not be. 402 void summarize_dense_prefix(HeapWord* beg, HeapWord* end); 403 404 HeapWord* summarize_split_space(size_t src_region, SplitInfo& split_info, 405 HeapWord* destination, HeapWord* target_end, 406 HeapWord** target_next); 407 bool summarize(SplitInfo& split_info, 408 HeapWord* source_beg, HeapWord* source_end, 409 HeapWord** source_next, 410 HeapWord* target_beg, HeapWord* target_end, 411 HeapWord** target_next); 412 413 void clear(); 414 void clear_range(size_t beg_region, size_t end_region); 415 void clear_range(HeapWord* beg, HeapWord* end) { 416 clear_range(addr_to_region_idx(beg), addr_to_region_idx(end)); 417 } 418 419 // Return the number of words between addr and the start of the region 420 // containing addr. 421 inline size_t region_offset(const HeapWord* addr) const; 422 423 // Convert addresses to/from a region index or region pointer. 424 inline size_t addr_to_region_idx(const HeapWord* addr) const; 425 inline RegionData* addr_to_region_ptr(const HeapWord* addr) const; 426 inline HeapWord* region_to_addr(size_t region) const; 427 inline HeapWord* region_to_addr(size_t region, size_t offset) const; 428 inline HeapWord* region_to_addr(const RegionData* region) const; 429 430 inline HeapWord* region_align_down(HeapWord* addr) const; 431 inline HeapWord* region_align_up(HeapWord* addr) const; 432 inline bool is_region_aligned(HeapWord* addr) const; 433 434 // Analogous to region_offset() for blocks. 435 size_t block_offset(const HeapWord* addr) const; 436 size_t addr_to_block_idx(const HeapWord* addr) const; 437 size_t addr_to_block_idx(const oop obj) const { 438 return addr_to_block_idx((HeapWord*) obj); 439 } 440 inline BlockData* addr_to_block_ptr(const HeapWord* addr) const; 441 inline HeapWord* block_to_addr(size_t block) const; 442 inline size_t region_to_block_idx(size_t region) const; 443 444 inline HeapWord* block_align_down(HeapWord* addr) const; 445 inline HeapWord* block_align_up(HeapWord* addr) const; 446 inline bool is_block_aligned(HeapWord* addr) const; 447 448 // Return the address one past the end of the partial object. 449 HeapWord* partial_obj_end(size_t region_idx) const; 450 451 // Return the location of the object after compaction. 452 HeapWord* calc_new_pointer(HeapWord* addr, ParCompactionManager* cm); 453 454 HeapWord* calc_new_pointer(oop p, ParCompactionManager* cm) { 455 return calc_new_pointer((HeapWord*) p, cm); 456 } 457 458 #ifdef ASSERT 459 void verify_clear(const PSVirtualSpace* vspace); 460 void verify_clear(); 461 #endif // #ifdef ASSERT 462 463 private: 464 bool initialize_block_data(); 465 bool initialize_region_data(size_t region_size); 466 PSVirtualSpace* create_vspace(size_t count, size_t element_size); 467 468 private: 469 HeapWord* _region_start; 470 #ifdef ASSERT 471 HeapWord* _region_end; 472 #endif // #ifdef ASSERT 473 474 PSVirtualSpace* _region_vspace; 475 size_t _reserved_byte_size; 476 RegionData* _region_data; 477 size_t _region_count; 478 479 PSVirtualSpace* _block_vspace; 480 BlockData* _block_data; 481 size_t _block_count; 482 }; 483 484 inline uint 485 ParallelCompactData::RegionData::destination_count_raw() const 486 { 487 return _dc_and_los & dc_mask; 488 } 489 490 inline uint 491 ParallelCompactData::RegionData::destination_count() const 492 { 493 return destination_count_raw() >> dc_shift; 494 } 495 496 inline bool 497 ParallelCompactData::RegionData::blocks_filled() const 498 { 499 bool result = _blocks_filled; 500 OrderAccess::acquire(); 501 return result; 502 } 503 504 #ifdef ASSERT 505 inline size_t 506 ParallelCompactData::RegionData::blocks_filled_count() const 507 { 508 return _blocks_filled_count; 509 } 510 #endif // #ifdef ASSERT 511 512 inline void 513 ParallelCompactData::RegionData::set_blocks_filled() 514 { 515 OrderAccess::release(); 516 _blocks_filled = true; 517 // Debug builds count the number of times the table was filled. 518 DEBUG_ONLY(Atomic::inc(&_blocks_filled_count)); 519 } 520 521 inline void 522 ParallelCompactData::RegionData::set_destination_count(uint count) 523 { 524 assert(count <= (dc_completed >> dc_shift), "count too large"); 525 const region_sz_t live_sz = (region_sz_t) live_obj_size(); 526 _dc_and_los = (count << dc_shift) | live_sz; 527 } 528 529 inline void ParallelCompactData::RegionData::set_live_obj_size(size_t words) 530 { 531 assert(words <= los_mask, "would overflow"); 532 _dc_and_los = destination_count_raw() | (region_sz_t)words; 533 } 534 535 inline void ParallelCompactData::RegionData::decrement_destination_count() 536 { 537 assert(_dc_and_los < dc_claimed, "already claimed"); 538 assert(_dc_and_los >= dc_one, "count would go negative"); 539 Atomic::add(dc_mask, &_dc_and_los); 540 } 541 542 inline HeapWord* ParallelCompactData::RegionData::data_location() const 543 { 544 DEBUG_ONLY(return _data_location;) 545 NOT_DEBUG(return NULL;) 546 } 547 548 inline HeapWord* ParallelCompactData::RegionData::highest_ref() const 549 { 550 DEBUG_ONLY(return _highest_ref;) 551 NOT_DEBUG(return NULL;) 552 } 553 554 inline void ParallelCompactData::RegionData::set_data_location(HeapWord* addr) 555 { 556 DEBUG_ONLY(_data_location = addr;) 557 } 558 559 inline void ParallelCompactData::RegionData::set_completed() 560 { 561 assert(claimed(), "must be claimed first"); 562 _dc_and_los = dc_completed | (region_sz_t) live_obj_size(); 563 } 564 565 // MT-unsafe claiming of a region. Should only be used during single threaded 566 // execution. 567 inline bool ParallelCompactData::RegionData::claim_unsafe() 568 { 569 if (available()) { 570 _dc_and_los |= dc_claimed; 571 return true; 572 } 573 return false; 574 } 575 576 inline void ParallelCompactData::RegionData::add_live_obj(size_t words) 577 { 578 assert(words <= (size_t)los_mask - live_obj_size(), "overflow"); 579 Atomic::add(static_cast<region_sz_t>(words), &_dc_and_los); 580 } 581 582 inline void ParallelCompactData::RegionData::set_highest_ref(HeapWord* addr) 583 { 584 #ifdef ASSERT 585 HeapWord* tmp = _highest_ref; 586 while (addr > tmp) { 587 tmp = Atomic::cmpxchg(addr, &_highest_ref, tmp); 588 } 589 #endif // #ifdef ASSERT 590 } 591 592 inline bool ParallelCompactData::RegionData::claim() 593 { 594 const region_sz_t los = static_cast<region_sz_t>(live_obj_size()); 595 const region_sz_t old = Atomic::cmpxchg(dc_claimed | los, &_dc_and_los, los); 596 return old == los; 597 } 598 599 inline ParallelCompactData::RegionData* 600 ParallelCompactData::region(size_t region_idx) const 601 { 602 assert(region_idx <= region_count(), "bad arg"); 603 return _region_data + region_idx; 604 } 605 606 inline size_t 607 ParallelCompactData::region(const RegionData* const region_ptr) const 608 { 609 assert(region_ptr >= _region_data, "bad arg"); 610 assert(region_ptr <= _region_data + region_count(), "bad arg"); 611 return pointer_delta(region_ptr, _region_data, sizeof(RegionData)); 612 } 613 614 inline ParallelCompactData::BlockData* 615 ParallelCompactData::block(size_t n) const { 616 assert(n < block_count(), "bad arg"); 617 return _block_data + n; 618 } 619 620 inline size_t 621 ParallelCompactData::region_offset(const HeapWord* addr) const 622 { 623 assert(addr >= _region_start, "bad addr"); 624 assert(addr <= _region_end, "bad addr"); 625 return (size_t(addr) & RegionAddrOffsetMask) >> LogHeapWordSize; 626 } 627 628 inline size_t 629 ParallelCompactData::addr_to_region_idx(const HeapWord* addr) const 630 { 631 assert(addr >= _region_start, "bad addr " PTR_FORMAT " _region_start " PTR_FORMAT, p2i(addr), p2i(_region_start)); 632 assert(addr <= _region_end, "bad addr " PTR_FORMAT " _region_end " PTR_FORMAT, p2i(addr), p2i(_region_end)); 633 return pointer_delta(addr, _region_start) >> Log2RegionSize; 634 } 635 636 inline ParallelCompactData::RegionData* 637 ParallelCompactData::addr_to_region_ptr(const HeapWord* addr) const 638 { 639 return region(addr_to_region_idx(addr)); 640 } 641 642 inline HeapWord* 643 ParallelCompactData::region_to_addr(size_t region) const 644 { 645 assert(region <= _region_count, "region out of range"); 646 return _region_start + (region << Log2RegionSize); 647 } 648 649 inline HeapWord* 650 ParallelCompactData::region_to_addr(const RegionData* region) const 651 { 652 return region_to_addr(pointer_delta(region, _region_data, 653 sizeof(RegionData))); 654 } 655 656 inline HeapWord* 657 ParallelCompactData::region_to_addr(size_t region, size_t offset) const 658 { 659 assert(region <= _region_count, "region out of range"); 660 assert(offset < RegionSize, "offset too big"); // This may be too strict. 661 return region_to_addr(region) + offset; 662 } 663 664 inline HeapWord* 665 ParallelCompactData::region_align_down(HeapWord* addr) const 666 { 667 assert(addr >= _region_start, "bad addr"); 668 assert(addr < _region_end + RegionSize, "bad addr"); 669 return (HeapWord*)(size_t(addr) & RegionAddrMask); 670 } 671 672 inline HeapWord* 673 ParallelCompactData::region_align_up(HeapWord* addr) const 674 { 675 assert(addr >= _region_start, "bad addr"); 676 assert(addr <= _region_end, "bad addr"); 677 return region_align_down(addr + RegionSizeOffsetMask); 678 } 679 680 inline bool 681 ParallelCompactData::is_region_aligned(HeapWord* addr) const 682 { 683 return region_offset(addr) == 0; 684 } 685 686 inline size_t 687 ParallelCompactData::block_offset(const HeapWord* addr) const 688 { 689 assert(addr >= _region_start, "bad addr"); 690 assert(addr <= _region_end, "bad addr"); 691 return (size_t(addr) & BlockAddrOffsetMask) >> LogHeapWordSize; 692 } 693 694 inline size_t 695 ParallelCompactData::addr_to_block_idx(const HeapWord* addr) const 696 { 697 assert(addr >= _region_start, "bad addr"); 698 assert(addr <= _region_end, "bad addr"); 699 return pointer_delta(addr, _region_start) >> Log2BlockSize; 700 } 701 702 inline ParallelCompactData::BlockData* 703 ParallelCompactData::addr_to_block_ptr(const HeapWord* addr) const 704 { 705 return block(addr_to_block_idx(addr)); 706 } 707 708 inline HeapWord* 709 ParallelCompactData::block_to_addr(size_t block) const 710 { 711 assert(block < _block_count, "block out of range"); 712 return _region_start + (block << Log2BlockSize); 713 } 714 715 inline size_t 716 ParallelCompactData::region_to_block_idx(size_t region) const 717 { 718 return region << Log2BlocksPerRegion; 719 } 720 721 inline HeapWord* 722 ParallelCompactData::block_align_down(HeapWord* addr) const 723 { 724 assert(addr >= _region_start, "bad addr"); 725 assert(addr < _region_end + RegionSize, "bad addr"); 726 return (HeapWord*)(size_t(addr) & BlockAddrMask); 727 } 728 729 inline HeapWord* 730 ParallelCompactData::block_align_up(HeapWord* addr) const 731 { 732 assert(addr >= _region_start, "bad addr"); 733 assert(addr <= _region_end, "bad addr"); 734 return block_align_down(addr + BlockSizeOffsetMask); 735 } 736 737 inline bool 738 ParallelCompactData::is_block_aligned(HeapWord* addr) const 739 { 740 return block_offset(addr) == 0; 741 } 742 743 // Abstract closure for use with ParMarkBitMap::iterate(), which will invoke the 744 // do_addr() method. 745 // 746 // The closure is initialized with the number of heap words to process 747 // (words_remaining()), and becomes 'full' when it reaches 0. The do_addr() 748 // methods in subclasses should update the total as words are processed. Since 749 // only one subclass actually uses this mechanism to terminate iteration, the 750 // default initial value is > 0. The implementation is here and not in the 751 // single subclass that uses it to avoid making is_full() virtual, and thus 752 // adding a virtual call per live object. 753 754 class ParMarkBitMapClosure: public StackObj { 755 public: 756 typedef ParMarkBitMap::idx_t idx_t; 757 typedef ParMarkBitMap::IterationStatus IterationStatus; 758 759 public: 760 inline ParMarkBitMapClosure(ParMarkBitMap* mbm, ParCompactionManager* cm, 761 size_t words = max_uintx); 762 763 inline ParCompactionManager* compaction_manager() const; 764 inline ParMarkBitMap* bitmap() const; 765 inline size_t words_remaining() const; 766 inline bool is_full() const; 767 inline HeapWord* source() const; 768 769 inline void set_source(HeapWord* addr); 770 771 virtual IterationStatus do_addr(HeapWord* addr, size_t words) = 0; 772 773 protected: 774 inline void decrement_words_remaining(size_t words); 775 776 private: 777 ParMarkBitMap* const _bitmap; 778 ParCompactionManager* const _compaction_manager; 779 DEBUG_ONLY(const size_t _initial_words_remaining;) // Useful in debugger. 780 size_t _words_remaining; // Words left to copy. 781 782 protected: 783 HeapWord* _source; // Next addr that would be read. 784 }; 785 786 inline 787 ParMarkBitMapClosure::ParMarkBitMapClosure(ParMarkBitMap* bitmap, 788 ParCompactionManager* cm, 789 size_t words): 790 _bitmap(bitmap), _compaction_manager(cm) 791 #ifdef ASSERT 792 , _initial_words_remaining(words) 793 #endif 794 { 795 _words_remaining = words; 796 _source = NULL; 797 } 798 799 inline ParCompactionManager* ParMarkBitMapClosure::compaction_manager() const { 800 return _compaction_manager; 801 } 802 803 inline ParMarkBitMap* ParMarkBitMapClosure::bitmap() const { 804 return _bitmap; 805 } 806 807 inline size_t ParMarkBitMapClosure::words_remaining() const { 808 return _words_remaining; 809 } 810 811 inline bool ParMarkBitMapClosure::is_full() const { 812 return words_remaining() == 0; 813 } 814 815 inline HeapWord* ParMarkBitMapClosure::source() const { 816 return _source; 817 } 818 819 inline void ParMarkBitMapClosure::set_source(HeapWord* addr) { 820 _source = addr; 821 } 822 823 inline void ParMarkBitMapClosure::decrement_words_remaining(size_t words) { 824 assert(_words_remaining >= words, "processed too many words"); 825 _words_remaining -= words; 826 } 827 828 // The UseParallelOldGC collector is a stop-the-world garbage collector that 829 // does parts of the collection using parallel threads. The collection includes 830 // the tenured generation and the young generation. The permanent generation is 831 // collected at the same time as the other two generations but the permanent 832 // generation is collect by a single GC thread. The permanent generation is 833 // collected serially because of the requirement that during the processing of a 834 // klass AAA, any objects reference by AAA must already have been processed. 835 // This requirement is enforced by a left (lower address) to right (higher 836 // address) sliding compaction. 837 // 838 // There are four phases of the collection. 839 // 840 // - marking phase 841 // - summary phase 842 // - compacting phase 843 // - clean up phase 844 // 845 // Roughly speaking these phases correspond, respectively, to 846 // - mark all the live objects 847 // - calculate the destination of each object at the end of the collection 848 // - move the objects to their destination 849 // - update some references and reinitialize some variables 850 // 851 // These three phases are invoked in PSParallelCompact::invoke_no_policy(). The 852 // marking phase is implemented in PSParallelCompact::marking_phase() and does a 853 // complete marking of the heap. The summary phase is implemented in 854 // PSParallelCompact::summary_phase(). The move and update phase is implemented 855 // in PSParallelCompact::compact(). 856 // 857 // A space that is being collected is divided into regions and with each region 858 // is associated an object of type ParallelCompactData. Each region is of a 859 // fixed size and typically will contain more than 1 object and may have parts 860 // of objects at the front and back of the region. 861 // 862 // region -----+---------------------+---------- 863 // objects covered [ AAA )[ BBB )[ CCC )[ DDD ) 864 // 865 // The marking phase does a complete marking of all live objects in the heap. 866 // The marking also compiles the size of the data for all live objects covered 867 // by the region. This size includes the part of any live object spanning onto 868 // the region (part of AAA if it is live) from the front, all live objects 869 // contained in the region (BBB and/or CCC if they are live), and the part of 870 // any live objects covered by the region that extends off the region (part of 871 // DDD if it is live). The marking phase uses multiple GC threads and marking 872 // is done in a bit array of type ParMarkBitMap. The marking of the bit map is 873 // done atomically as is the accumulation of the size of the live objects 874 // covered by a region. 875 // 876 // The summary phase calculates the total live data to the left of each region 877 // XXX. Based on that total and the bottom of the space, it can calculate the 878 // starting location of the live data in XXX. The summary phase calculates for 879 // each region XXX quantities such as 880 // 881 // - the amount of live data at the beginning of a region from an object 882 // entering the region. 883 // - the location of the first live data on the region 884 // - a count of the number of regions receiving live data from XXX. 885 // 886 // See ParallelCompactData for precise details. The summary phase also 887 // calculates the dense prefix for the compaction. The dense prefix is a 888 // portion at the beginning of the space that is not moved. The objects in the 889 // dense prefix do need to have their object references updated. See method 890 // summarize_dense_prefix(). 891 // 892 // The summary phase is done using 1 GC thread. 893 // 894 // The compaction phase moves objects to their new location and updates all 895 // references in the object. 896 // 897 // A current exception is that objects that cross a region boundary are moved 898 // but do not have their references updated. References are not updated because 899 // it cannot easily be determined if the klass pointer KKK for the object AAA 900 // has been updated. KKK likely resides in a region to the left of the region 901 // containing AAA. These AAA's have there references updated at the end in a 902 // clean up phase. See the method PSParallelCompact::update_deferred_objects(). 903 // An alternate strategy is being investigated for this deferral of updating. 904 // 905 // Compaction is done on a region basis. A region that is ready to be filled is 906 // put on a ready list and GC threads take region off the list and fill them. A 907 // region is ready to be filled if it empty of live objects. Such a region may 908 // have been initially empty (only contained dead objects) or may have had all 909 // its live objects copied out already. A region that compacts into itself is 910 // also ready for filling. The ready list is initially filled with empty 911 // regions and regions compacting into themselves. There is always at least 1 912 // region that can be put on the ready list. The regions are atomically added 913 // and removed from the ready list. 914 915 class TaskQueue; 916 917 class PSParallelCompact : AllStatic { 918 public: 919 // Convenient access to type names. 920 typedef ParMarkBitMap::idx_t idx_t; 921 typedef ParallelCompactData::RegionData RegionData; 922 typedef ParallelCompactData::BlockData BlockData; 923 924 typedef enum { 925 old_space_id, eden_space_id, 926 from_space_id, to_space_id, last_space_id 927 } SpaceId; 928 929 struct UpdateDensePrefixTask : public CHeapObj<mtGC> { 930 SpaceId _space_id; 931 size_t _region_index_start; 932 size_t _region_index_end; 933 934 UpdateDensePrefixTask() : 935 _space_id(SpaceId(0)), 936 _region_index_start(0), 937 _region_index_end(0) {} 938 939 UpdateDensePrefixTask(SpaceId space_id, 940 size_t region_index_start, 941 size_t region_index_end) : 942 _space_id(space_id), 943 _region_index_start(region_index_start), 944 _region_index_end(region_index_end) {} 945 }; 946 947 public: 948 // Inline closure decls 949 // 950 class IsAliveClosure: public BoolObjectClosure { 951 public: 952 virtual bool do_object_b(oop p); 953 }; 954 955 friend class RefProcTaskProxy; 956 friend class PSParallelCompactTest; 957 958 private: 959 static STWGCTimer _gc_timer; 960 static ParallelOldTracer _gc_tracer; 961 static elapsedTimer _accumulated_time; 962 static unsigned int _total_invocations; 963 static unsigned int _maximum_compaction_gc_num; 964 static jlong _time_of_last_gc; // ms 965 static CollectorCounters* _counters; 966 static ParMarkBitMap _mark_bitmap; 967 static ParallelCompactData _summary_data; 968 static IsAliveClosure _is_alive_closure; 969 static SpaceInfo _space_info[last_space_id]; 970 971 // Reference processing (used in ...follow_contents) 972 static SpanSubjectToDiscoveryClosure _span_based_discoverer; 973 static ReferenceProcessor* _ref_processor; 974 975 // Values computed at initialization and used by dead_wood_limiter(). 976 static double _dwl_mean; 977 static double _dwl_std_dev; 978 static double _dwl_first_term; 979 static double _dwl_adjustment; 980 #ifdef ASSERT 981 static bool _dwl_initialized; 982 #endif // #ifdef ASSERT 983 984 public: 985 static ParallelOldTracer* gc_tracer() { return &_gc_tracer; } 986 987 private: 988 989 static void initialize_space_info(); 990 991 // Clear the marking bitmap and summary data that cover the specified space. 992 static void clear_data_covering_space(SpaceId id); 993 994 static void pre_compact(); 995 static void post_compact(); 996 997 // Mark live objects 998 static void marking_phase(ParCompactionManager* cm, 999 bool maximum_heap_compaction, 1000 ParallelOldTracer *gc_tracer); 1001 1002 // Compute the dense prefix for the designated space. This is an experimental 1003 // implementation currently not used in production. 1004 static HeapWord* compute_dense_prefix_via_density(const SpaceId id, 1005 bool maximum_compaction); 1006 1007 // Methods used to compute the dense prefix. 1008 1009 // Compute the value of the normal distribution at x = density. The mean and 1010 // standard deviation are values saved by initialize_dead_wood_limiter(). 1011 static inline double normal_distribution(double density); 1012 1013 // Initialize the static vars used by dead_wood_limiter(). 1014 static void initialize_dead_wood_limiter(); 1015 1016 // Return the percentage of space that can be treated as "dead wood" (i.e., 1017 // not reclaimed). 1018 static double dead_wood_limiter(double density, size_t min_percent); 1019 1020 // Find the first (left-most) region in the range [beg, end) that has at least 1021 // dead_words of dead space to the left. The argument beg must be the first 1022 // region in the space that is not completely live. 1023 static RegionData* dead_wood_limit_region(const RegionData* beg, 1024 const RegionData* end, 1025 size_t dead_words); 1026 1027 // Return a pointer to the first region in the range [beg, end) that is not 1028 // completely full. 1029 static RegionData* first_dead_space_region(const RegionData* beg, 1030 const RegionData* end); 1031 1032 // Return a value indicating the benefit or 'yield' if the compacted region 1033 // were to start (or equivalently if the dense prefix were to end) at the 1034 // candidate region. Higher values are better. 1035 // 1036 // The value is based on the amount of space reclaimed vs. the costs of (a) 1037 // updating references in the dense prefix plus (b) copying objects and 1038 // updating references in the compacted region. 1039 static inline double reclaimed_ratio(const RegionData* const candidate, 1040 HeapWord* const bottom, 1041 HeapWord* const top, 1042 HeapWord* const new_top); 1043 1044 // Compute the dense prefix for the designated space. 1045 static HeapWord* compute_dense_prefix(const SpaceId id, 1046 bool maximum_compaction); 1047 1048 // Return true if dead space crosses onto the specified Region; bit must be 1049 // the bit index corresponding to the first word of the Region. 1050 static inline bool dead_space_crosses_boundary(const RegionData* region, 1051 idx_t bit); 1052 1053 // Summary phase utility routine to fill dead space (if any) at the dense 1054 // prefix boundary. Should only be called if the the dense prefix is 1055 // non-empty. 1056 static void fill_dense_prefix_end(SpaceId id); 1057 1058 static void summarize_spaces_quick(); 1059 static void summarize_space(SpaceId id, bool maximum_compaction); 1060 static void summary_phase(ParCompactionManager* cm, bool maximum_compaction); 1061 1062 // Adjust addresses in roots. Does not adjust addresses in heap. 1063 static void adjust_roots(ParCompactionManager* cm); 1064 1065 DEBUG_ONLY(static void write_block_fill_histogram();) 1066 1067 // Move objects to new locations. 1068 static void compact_perm(ParCompactionManager* cm); 1069 static void compact(); 1070 1071 // Add available regions to the stack and draining tasks to the task queue. 1072 static void prepare_region_draining_tasks(uint parallel_gc_threads); 1073 1074 // Add dense prefix update tasks to the task queue. 1075 static void enqueue_dense_prefix_tasks(TaskQueue& task_queue, 1076 uint parallel_gc_threads); 1077 1078 // If objects are left in eden after a collection, try to move the boundary 1079 // and absorb them into the old gen. Returns true if eden was emptied. 1080 static bool absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, 1081 PSYoungGen* young_gen, 1082 PSOldGen* old_gen); 1083 1084 // Reset time since last full gc 1085 static void reset_millis_since_last_gc(); 1086 1087 #ifndef PRODUCT 1088 // Print generic summary data 1089 static void print_generic_summary_data(ParallelCompactData& summary_data, 1090 HeapWord* const beg_addr, 1091 HeapWord* const end_addr); 1092 #endif // #ifndef PRODUCT 1093 1094 public: 1095 1096 PSParallelCompact(); 1097 1098 static void invoke(bool maximum_heap_compaction); 1099 static bool invoke_no_policy(bool maximum_heap_compaction); 1100 1101 static void post_initialize(); 1102 // Perform initialization for PSParallelCompact that requires 1103 // allocations. This should be called during the VM initialization 1104 // at a pointer where it would be appropriate to return a JNI_ENOMEM 1105 // in the event of a failure. 1106 static bool initialize(); 1107 1108 // Closure accessors 1109 static BoolObjectClosure* is_alive_closure() { return (BoolObjectClosure*)&_is_alive_closure; } 1110 1111 // Public accessors 1112 static elapsedTimer* accumulated_time() { return &_accumulated_time; } 1113 static unsigned int total_invocations() { return _total_invocations; } 1114 static CollectorCounters* counters() { return _counters; } 1115 1116 // Marking support 1117 static inline bool mark_obj(oop obj); 1118 static inline bool is_marked(oop obj); 1119 1120 template <class T> static inline void adjust_pointer(T* p, ParCompactionManager* cm); 1121 1122 // Compaction support. 1123 // Return true if p is in the range [beg_addr, end_addr). 1124 static inline bool is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr); 1125 static inline bool is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr); 1126 1127 // Convenience wrappers for per-space data kept in _space_info. 1128 static inline MutableSpace* space(SpaceId space_id); 1129 static inline HeapWord* new_top(SpaceId space_id); 1130 static inline HeapWord* dense_prefix(SpaceId space_id); 1131 static inline ObjectStartArray* start_array(SpaceId space_id); 1132 1133 // Process the end of the given region range in the dense prefix. 1134 // This includes saving any object not updated. 1135 static void dense_prefix_regions_epilogue(ParCompactionManager* cm, 1136 size_t region_start_index, 1137 size_t region_end_index, 1138 idx_t exiting_object_offset, 1139 idx_t region_offset_start, 1140 idx_t region_offset_end); 1141 1142 // Update a region in the dense prefix. For each live object 1143 // in the region, update it's interior references. For each 1144 // dead object, fill it with deadwood. Dead space at the end 1145 // of a region range will be filled to the start of the next 1146 // live object regardless of the region_index_end. None of the 1147 // objects in the dense prefix move and dead space is dead 1148 // (holds only dead objects that don't need any processing), so 1149 // dead space can be filled in any order. 1150 static void update_and_deadwood_in_dense_prefix(ParCompactionManager* cm, 1151 SpaceId space_id, 1152 size_t region_index_start, 1153 size_t region_index_end); 1154 1155 // Return the address of the count + 1st live word in the range [beg, end). 1156 static HeapWord* skip_live_words(HeapWord* beg, HeapWord* end, size_t count); 1157 1158 // Return the address of the word to be copied to dest_addr, which must be 1159 // aligned to a region boundary. 1160 static HeapWord* first_src_addr(HeapWord* const dest_addr, 1161 SpaceId src_space_id, 1162 size_t src_region_idx); 1163 1164 // Determine the next source region, set closure.source() to the start of the 1165 // new region return the region index. Parameter end_addr is the address one 1166 // beyond the end of source range just processed. If necessary, switch to a 1167 // new source space and set src_space_id (in-out parameter) and src_space_top 1168 // (out parameter) accordingly. 1169 static size_t next_src_region(MoveAndUpdateClosure& closure, 1170 SpaceId& src_space_id, 1171 HeapWord*& src_space_top, 1172 HeapWord* end_addr); 1173 1174 // Decrement the destination count for each non-empty source region in the 1175 // range [beg_region, region(region_align_up(end_addr))). If the destination 1176 // count for a region goes to 0 and it needs to be filled, enqueue it. 1177 static void decrement_destination_counts(ParCompactionManager* cm, 1178 SpaceId src_space_id, 1179 size_t beg_region, 1180 HeapWord* end_addr); 1181 1182 // Fill a region, copying objects from one or more source regions. 1183 static void fill_region(ParCompactionManager* cm, size_t region_idx); 1184 static void fill_and_update_region(ParCompactionManager* cm, size_t region) { 1185 fill_region(cm, region); 1186 } 1187 1188 // Fill in the block table for the specified region. 1189 static void fill_blocks(size_t region_idx); 1190 1191 // Update the deferred objects in the space. 1192 static void update_deferred_objects(ParCompactionManager* cm, SpaceId id); 1193 1194 static ParMarkBitMap* mark_bitmap() { return &_mark_bitmap; } 1195 static ParallelCompactData& summary_data() { return _summary_data; } 1196 1197 // Reference Processing 1198 static ReferenceProcessor* const ref_processor() { return _ref_processor; } 1199 1200 static STWGCTimer* gc_timer() { return &_gc_timer; } 1201 1202 // Return the SpaceId for the given address. 1203 static SpaceId space_id(HeapWord* addr); 1204 1205 // Time since last full gc (in milliseconds). 1206 static jlong millis_since_last_gc(); 1207 1208 static void print_on_error(outputStream* st); 1209 1210 #ifndef PRODUCT 1211 // Debugging support. 1212 static const char* space_names[last_space_id]; 1213 static void print_region_ranges(); 1214 static void print_dense_prefix_stats(const char* const algorithm, 1215 const SpaceId id, 1216 const bool maximum_compaction, 1217 HeapWord* const addr); 1218 static void summary_phase_msg(SpaceId dst_space_id, 1219 HeapWord* dst_beg, HeapWord* dst_end, 1220 SpaceId src_space_id, 1221 HeapWord* src_beg, HeapWord* src_end); 1222 #endif // #ifndef PRODUCT 1223 1224 #ifdef ASSERT 1225 // Sanity check the new location of a word in the heap. 1226 static inline void check_new_location(HeapWord* old_addr, HeapWord* new_addr); 1227 // Verify that all the regions have been emptied. 1228 static void verify_complete(SpaceId space_id); 1229 #endif // #ifdef ASSERT 1230 }; 1231 1232 class MoveAndUpdateClosure: public ParMarkBitMapClosure { 1233 public: 1234 inline MoveAndUpdateClosure(ParMarkBitMap* bitmap, ParCompactionManager* cm, 1235 ObjectStartArray* start_array, 1236 HeapWord* destination, size_t words); 1237 1238 // Accessors. 1239 HeapWord* destination() const { return _destination; } 1240 1241 // If the object will fit (size <= words_remaining()), copy it to the current 1242 // destination, update the interior oops and the start array and return either 1243 // full (if the closure is full) or incomplete. If the object will not fit, 1244 // return would_overflow. 1245 virtual IterationStatus do_addr(HeapWord* addr, size_t size); 1246 1247 // Copy enough words to fill this closure, starting at source(). Interior 1248 // oops and the start array are not updated. Return full. 1249 IterationStatus copy_until_full(); 1250 1251 // Copy enough words to fill this closure or to the end of an object, 1252 // whichever is smaller, starting at source(). Interior oops and the start 1253 // array are not updated. 1254 void copy_partial_obj(); 1255 1256 protected: 1257 // Update variables to indicate that word_count words were processed. 1258 inline void update_state(size_t word_count); 1259 1260 protected: 1261 ObjectStartArray* const _start_array; 1262 HeapWord* _destination; // Next addr to be written. 1263 }; 1264 1265 inline 1266 MoveAndUpdateClosure::MoveAndUpdateClosure(ParMarkBitMap* bitmap, 1267 ParCompactionManager* cm, 1268 ObjectStartArray* start_array, 1269 HeapWord* destination, 1270 size_t words) : 1271 ParMarkBitMapClosure(bitmap, cm, words), _start_array(start_array) 1272 { 1273 _destination = destination; 1274 } 1275 1276 inline void MoveAndUpdateClosure::update_state(size_t words) 1277 { 1278 decrement_words_remaining(words); 1279 _source += words; 1280 _destination += words; 1281 } 1282 1283 class UpdateOnlyClosure: public ParMarkBitMapClosure { 1284 private: 1285 const PSParallelCompact::SpaceId _space_id; 1286 ObjectStartArray* const _start_array; 1287 1288 public: 1289 UpdateOnlyClosure(ParMarkBitMap* mbm, 1290 ParCompactionManager* cm, 1291 PSParallelCompact::SpaceId space_id); 1292 1293 // Update the object. 1294 virtual IterationStatus do_addr(HeapWord* addr, size_t words); 1295 1296 inline void do_addr(HeapWord* addr); 1297 }; 1298 1299 class FillClosure: public ParMarkBitMapClosure { 1300 public: 1301 FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id); 1302 1303 virtual IterationStatus do_addr(HeapWord* addr, size_t size); 1304 1305 private: 1306 ObjectStartArray* const _start_array; 1307 }; 1308 1309 #endif // SHARE_GC_PARALLEL_PSPARALLELCOMPACT_HPP