1 /* 2 * Copyright (c) 2005, 2018, 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 "aot/aotLoader.hpp" 27 #include "classfile/classLoaderDataGraph.hpp" 28 #include "classfile/javaClasses.inline.hpp" 29 #include "classfile/stringTable.hpp" 30 #include "classfile/symbolTable.hpp" 31 #include "classfile/systemDictionary.hpp" 32 #include "code/codeCache.hpp" 33 #include "gc/parallel/gcTaskManager.hpp" 34 #include "gc/parallel/parallelScavengeHeap.inline.hpp" 35 #include "gc/parallel/parMarkBitMap.inline.hpp" 36 #include "gc/parallel/pcTasks.hpp" 37 #include "gc/parallel/psAdaptiveSizePolicy.hpp" 38 #include "gc/parallel/psCompactionManager.inline.hpp" 39 #include "gc/parallel/psOldGen.hpp" 40 #include "gc/parallel/psParallelCompact.inline.hpp" 41 #include "gc/parallel/psPromotionManager.inline.hpp" 42 #include "gc/parallel/psScavenge.hpp" 43 #include "gc/parallel/psYoungGen.hpp" 44 #include "gc/shared/gcCause.hpp" 45 #include "gc/shared/gcHeapSummary.hpp" 46 #include "gc/shared/gcId.hpp" 47 #include "gc/shared/gcLocker.hpp" 48 #include "gc/shared/gcTimer.hpp" 49 #include "gc/shared/gcTrace.hpp" 50 #include "gc/shared/gcTraceTime.inline.hpp" 51 #include "gc/shared/isGCActiveMark.hpp" 52 #include "gc/shared/referencePolicy.hpp" 53 #include "gc/shared/referenceProcessor.hpp" 54 #include "gc/shared/referenceProcessorPhaseTimes.hpp" 55 #include "gc/shared/spaceDecorator.hpp" 56 #include "gc/shared/weakProcessor.hpp" 57 #include "logging/log.hpp" 58 #include "memory/iterator.inline.hpp" 59 #include "memory/resourceArea.hpp" 60 #include "oops/access.inline.hpp" 61 #include "oops/instanceClassLoaderKlass.inline.hpp" 62 #include "oops/instanceKlass.inline.hpp" 63 #include "oops/instanceMirrorKlass.inline.hpp" 64 #include "oops/methodData.hpp" 65 #include "oops/objArrayKlass.inline.hpp" 66 #include "oops/oop.inline.hpp" 67 #include "runtime/atomic.hpp" 68 #include "runtime/handles.inline.hpp" 69 #include "runtime/safepoint.hpp" 70 #include "runtime/vmThread.hpp" 71 #include "services/management.hpp" 72 #include "services/memTracker.hpp" 73 #include "services/memoryService.hpp" 74 #include "utilities/align.hpp" 75 #include "utilities/debug.hpp" 76 #include "utilities/events.hpp" 77 #include "utilities/formatBuffer.hpp" 78 #include "utilities/macros.hpp" 79 #include "utilities/stack.inline.hpp" 80 81 #include <math.h> 82 83 // All sizes are in HeapWords. 84 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words 85 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize; 86 const size_t ParallelCompactData::RegionSizeBytes = 87 RegionSize << LogHeapWordSize; 88 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1; 89 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1; 90 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask; 91 92 const size_t ParallelCompactData::Log2BlockSize = 7; // 128 words 93 const size_t ParallelCompactData::BlockSize = (size_t)1 << Log2BlockSize; 94 const size_t ParallelCompactData::BlockSizeBytes = 95 BlockSize << LogHeapWordSize; 96 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1; 97 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1; 98 const size_t ParallelCompactData::BlockAddrMask = ~BlockAddrOffsetMask; 99 100 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize; 101 const size_t ParallelCompactData::Log2BlocksPerRegion = 102 Log2RegionSize - Log2BlockSize; 103 104 const ParallelCompactData::RegionData::region_sz_t 105 ParallelCompactData::RegionData::dc_shift = 27; 106 107 const ParallelCompactData::RegionData::region_sz_t 108 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift; 109 110 const ParallelCompactData::RegionData::region_sz_t 111 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift; 112 113 const ParallelCompactData::RegionData::region_sz_t 114 ParallelCompactData::RegionData::los_mask = ~dc_mask; 115 116 const ParallelCompactData::RegionData::region_sz_t 117 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift; 118 119 const ParallelCompactData::RegionData::region_sz_t 120 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift; 121 122 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id]; 123 124 SpanSubjectToDiscoveryClosure PSParallelCompact::_span_based_discoverer; 125 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL; 126 127 double PSParallelCompact::_dwl_mean; 128 double PSParallelCompact::_dwl_std_dev; 129 double PSParallelCompact::_dwl_first_term; 130 double PSParallelCompact::_dwl_adjustment; 131 #ifdef ASSERT 132 bool PSParallelCompact::_dwl_initialized = false; 133 #endif // #ifdef ASSERT 134 135 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size, 136 HeapWord* destination) 137 { 138 assert(src_region_idx != 0, "invalid src_region_idx"); 139 assert(partial_obj_size != 0, "invalid partial_obj_size argument"); 140 assert(destination != NULL, "invalid destination argument"); 141 142 _src_region_idx = src_region_idx; 143 _partial_obj_size = partial_obj_size; 144 _destination = destination; 145 146 // These fields may not be updated below, so make sure they're clear. 147 assert(_dest_region_addr == NULL, "should have been cleared"); 148 assert(_first_src_addr == NULL, "should have been cleared"); 149 150 // Determine the number of destination regions for the partial object. 151 HeapWord* const last_word = destination + partial_obj_size - 1; 152 const ParallelCompactData& sd = PSParallelCompact::summary_data(); 153 HeapWord* const beg_region_addr = sd.region_align_down(destination); 154 HeapWord* const end_region_addr = sd.region_align_down(last_word); 155 156 if (beg_region_addr == end_region_addr) { 157 // One destination region. 158 _destination_count = 1; 159 if (end_region_addr == destination) { 160 // The destination falls on a region boundary, thus the first word of the 161 // partial object will be the first word copied to the destination region. 162 _dest_region_addr = end_region_addr; 163 _first_src_addr = sd.region_to_addr(src_region_idx); 164 } 165 } else { 166 // Two destination regions. When copied, the partial object will cross a 167 // destination region boundary, so a word somewhere within the partial 168 // object will be the first word copied to the second destination region. 169 _destination_count = 2; 170 _dest_region_addr = end_region_addr; 171 const size_t ofs = pointer_delta(end_region_addr, destination); 172 assert(ofs < _partial_obj_size, "sanity"); 173 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs; 174 } 175 } 176 177 void SplitInfo::clear() 178 { 179 _src_region_idx = 0; 180 _partial_obj_size = 0; 181 _destination = NULL; 182 _destination_count = 0; 183 _dest_region_addr = NULL; 184 _first_src_addr = NULL; 185 assert(!is_valid(), "sanity"); 186 } 187 188 #ifdef ASSERT 189 void SplitInfo::verify_clear() 190 { 191 assert(_src_region_idx == 0, "not clear"); 192 assert(_partial_obj_size == 0, "not clear"); 193 assert(_destination == NULL, "not clear"); 194 assert(_destination_count == 0, "not clear"); 195 assert(_dest_region_addr == NULL, "not clear"); 196 assert(_first_src_addr == NULL, "not clear"); 197 } 198 #endif // #ifdef ASSERT 199 200 201 void PSParallelCompact::print_on_error(outputStream* st) { 202 _mark_bitmap.print_on_error(st); 203 } 204 205 #ifndef PRODUCT 206 const char* PSParallelCompact::space_names[] = { 207 "old ", "eden", "from", "to " 208 }; 209 210 void PSParallelCompact::print_region_ranges() { 211 if (!log_develop_is_enabled(Trace, gc, compaction)) { 212 return; 213 } 214 Log(gc, compaction) log; 215 ResourceMark rm; 216 LogStream ls(log.trace()); 217 Universe::print_on(&ls); 218 log.trace("space bottom top end new_top"); 219 log.trace("------ ---------- ---------- ---------- ----------"); 220 221 for (unsigned int id = 0; id < last_space_id; ++id) { 222 const MutableSpace* space = _space_info[id].space(); 223 log.trace("%u %s " 224 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " " 225 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ", 226 id, space_names[id], 227 summary_data().addr_to_region_idx(space->bottom()), 228 summary_data().addr_to_region_idx(space->top()), 229 summary_data().addr_to_region_idx(space->end()), 230 summary_data().addr_to_region_idx(_space_info[id].new_top())); 231 } 232 } 233 234 void 235 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c) 236 { 237 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7) 238 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5) 239 240 ParallelCompactData& sd = PSParallelCompact::summary_data(); 241 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0; 242 log_develop_trace(gc, compaction)( 243 REGION_IDX_FORMAT " " PTR_FORMAT " " 244 REGION_IDX_FORMAT " " PTR_FORMAT " " 245 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " " 246 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d", 247 i, p2i(c->data_location()), dci, p2i(c->destination()), 248 c->partial_obj_size(), c->live_obj_size(), 249 c->data_size(), c->source_region(), c->destination_count()); 250 251 #undef REGION_IDX_FORMAT 252 #undef REGION_DATA_FORMAT 253 } 254 255 void 256 print_generic_summary_data(ParallelCompactData& summary_data, 257 HeapWord* const beg_addr, 258 HeapWord* const end_addr) 259 { 260 size_t total_words = 0; 261 size_t i = summary_data.addr_to_region_idx(beg_addr); 262 const size_t last = summary_data.addr_to_region_idx(end_addr); 263 HeapWord* pdest = 0; 264 265 while (i < last) { 266 ParallelCompactData::RegionData* c = summary_data.region(i); 267 if (c->data_size() != 0 || c->destination() != pdest) { 268 print_generic_summary_region(i, c); 269 total_words += c->data_size(); 270 pdest = c->destination(); 271 } 272 ++i; 273 } 274 275 log_develop_trace(gc, compaction)("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize); 276 } 277 278 void 279 PSParallelCompact::print_generic_summary_data(ParallelCompactData& summary_data, 280 HeapWord* const beg_addr, 281 HeapWord* const end_addr) { 282 ::print_generic_summary_data(summary_data,beg_addr, end_addr); 283 } 284 285 void 286 print_generic_summary_data(ParallelCompactData& summary_data, 287 SpaceInfo* space_info) 288 { 289 if (!log_develop_is_enabled(Trace, gc, compaction)) { 290 return; 291 } 292 293 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) { 294 const MutableSpace* space = space_info[id].space(); 295 print_generic_summary_data(summary_data, space->bottom(), 296 MAX2(space->top(), space_info[id].new_top())); 297 } 298 } 299 300 void 301 print_initial_summary_data(ParallelCompactData& summary_data, 302 const MutableSpace* space) { 303 if (space->top() == space->bottom()) { 304 return; 305 } 306 307 const size_t region_size = ParallelCompactData::RegionSize; 308 typedef ParallelCompactData::RegionData RegionData; 309 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top()); 310 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up); 311 const RegionData* c = summary_data.region(end_region - 1); 312 HeapWord* end_addr = c->destination() + c->data_size(); 313 const size_t live_in_space = pointer_delta(end_addr, space->bottom()); 314 315 // Print (and count) the full regions at the beginning of the space. 316 size_t full_region_count = 0; 317 size_t i = summary_data.addr_to_region_idx(space->bottom()); 318 while (i < end_region && summary_data.region(i)->data_size() == region_size) { 319 ParallelCompactData::RegionData* c = summary_data.region(i); 320 log_develop_trace(gc, compaction)( 321 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d", 322 i, p2i(c->destination()), 323 c->partial_obj_size(), c->live_obj_size(), 324 c->data_size(), c->source_region(), c->destination_count()); 325 ++full_region_count; 326 ++i; 327 } 328 329 size_t live_to_right = live_in_space - full_region_count * region_size; 330 331 double max_reclaimed_ratio = 0.0; 332 size_t max_reclaimed_ratio_region = 0; 333 size_t max_dead_to_right = 0; 334 size_t max_live_to_right = 0; 335 336 // Print the 'reclaimed ratio' for regions while there is something live in 337 // the region or to the right of it. The remaining regions are empty (and 338 // uninteresting), and computing the ratio will result in division by 0. 339 while (i < end_region && live_to_right > 0) { 340 c = summary_data.region(i); 341 HeapWord* const region_addr = summary_data.region_to_addr(i); 342 const size_t used_to_right = pointer_delta(space->top(), region_addr); 343 const size_t dead_to_right = used_to_right - live_to_right; 344 const double reclaimed_ratio = double(dead_to_right) / live_to_right; 345 346 if (reclaimed_ratio > max_reclaimed_ratio) { 347 max_reclaimed_ratio = reclaimed_ratio; 348 max_reclaimed_ratio_region = i; 349 max_dead_to_right = dead_to_right; 350 max_live_to_right = live_to_right; 351 } 352 353 ParallelCompactData::RegionData* c = summary_data.region(i); 354 log_develop_trace(gc, compaction)( 355 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d" 356 "%12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10), 357 i, p2i(c->destination()), 358 c->partial_obj_size(), c->live_obj_size(), 359 c->data_size(), c->source_region(), c->destination_count(), 360 reclaimed_ratio, dead_to_right, live_to_right); 361 362 363 live_to_right -= c->data_size(); 364 ++i; 365 } 366 367 // Any remaining regions are empty. Print one more if there is one. 368 if (i < end_region) { 369 ParallelCompactData::RegionData* c = summary_data.region(i); 370 log_develop_trace(gc, compaction)( 371 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d", 372 i, p2i(c->destination()), 373 c->partial_obj_size(), c->live_obj_size(), 374 c->data_size(), c->source_region(), c->destination_count()); 375 } 376 377 log_develop_trace(gc, compaction)("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f", 378 max_reclaimed_ratio_region, max_dead_to_right, max_live_to_right, max_reclaimed_ratio); 379 } 380 381 void 382 print_initial_summary_data(ParallelCompactData& summary_data, 383 SpaceInfo* space_info) { 384 if (!log_develop_is_enabled(Trace, gc, compaction)) { 385 return; 386 } 387 388 unsigned int id = PSParallelCompact::old_space_id; 389 const MutableSpace* space; 390 do { 391 space = space_info[id].space(); 392 print_initial_summary_data(summary_data, space); 393 } while (++id < PSParallelCompact::eden_space_id); 394 395 do { 396 space = space_info[id].space(); 397 print_generic_summary_data(summary_data, space->bottom(), space->top()); 398 } while (++id < PSParallelCompact::last_space_id); 399 } 400 #endif // #ifndef PRODUCT 401 402 #ifdef ASSERT 403 size_t add_obj_count; 404 size_t add_obj_size; 405 size_t mark_bitmap_count; 406 size_t mark_bitmap_size; 407 #endif // #ifdef ASSERT 408 409 ParallelCompactData::ParallelCompactData() 410 { 411 _region_start = 0; 412 413 _region_vspace = 0; 414 _reserved_byte_size = 0; 415 _region_data = 0; 416 _region_count = 0; 417 418 _block_vspace = 0; 419 _block_data = 0; 420 _block_count = 0; 421 } 422 423 bool ParallelCompactData::initialize(MemRegion covered_region) 424 { 425 _region_start = covered_region.start(); 426 const size_t region_size = covered_region.word_size(); 427 DEBUG_ONLY(_region_end = _region_start + region_size;) 428 429 assert(region_align_down(_region_start) == _region_start, 430 "region start not aligned"); 431 assert((region_size & RegionSizeOffsetMask) == 0, 432 "region size not a multiple of RegionSize"); 433 434 bool result = initialize_region_data(region_size) && initialize_block_data(); 435 return result; 436 } 437 438 PSVirtualSpace* 439 ParallelCompactData::create_vspace(size_t count, size_t element_size) 440 { 441 const size_t raw_bytes = count * element_size; 442 const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10); 443 const size_t granularity = os::vm_allocation_granularity(); 444 _reserved_byte_size = align_up(raw_bytes, MAX2(page_sz, granularity)); 445 446 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 : 447 MAX2(page_sz, granularity); 448 ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0); 449 os::trace_page_sizes("Parallel Compact Data", raw_bytes, raw_bytes, page_sz, rs.base(), 450 rs.size()); 451 452 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC); 453 454 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz); 455 if (vspace != 0) { 456 if (vspace->expand_by(_reserved_byte_size)) { 457 return vspace; 458 } 459 delete vspace; 460 // Release memory reserved in the space. 461 rs.release(); 462 } 463 464 return 0; 465 } 466 467 bool ParallelCompactData::initialize_region_data(size_t region_size) 468 { 469 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize; 470 _region_vspace = create_vspace(count, sizeof(RegionData)); 471 if (_region_vspace != 0) { 472 _region_data = (RegionData*)_region_vspace->reserved_low_addr(); 473 _region_count = count; 474 return true; 475 } 476 return false; 477 } 478 479 bool ParallelCompactData::initialize_block_data() 480 { 481 assert(_region_count != 0, "region data must be initialized first"); 482 const size_t count = _region_count << Log2BlocksPerRegion; 483 _block_vspace = create_vspace(count, sizeof(BlockData)); 484 if (_block_vspace != 0) { 485 _block_data = (BlockData*)_block_vspace->reserved_low_addr(); 486 _block_count = count; 487 return true; 488 } 489 return false; 490 } 491 492 void ParallelCompactData::clear() 493 { 494 memset(_region_data, 0, _region_vspace->committed_size()); 495 memset(_block_data, 0, _block_vspace->committed_size()); 496 } 497 498 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) { 499 assert(beg_region <= _region_count, "beg_region out of range"); 500 assert(end_region <= _region_count, "end_region out of range"); 501 assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize"); 502 503 const size_t region_cnt = end_region - beg_region; 504 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData)); 505 506 const size_t beg_block = beg_region * BlocksPerRegion; 507 const size_t block_cnt = region_cnt * BlocksPerRegion; 508 memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData)); 509 } 510 511 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const 512 { 513 const RegionData* cur_cp = region(region_idx); 514 const RegionData* const end_cp = region(region_count() - 1); 515 516 HeapWord* result = region_to_addr(region_idx); 517 if (cur_cp < end_cp) { 518 do { 519 result += cur_cp->partial_obj_size(); 520 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp); 521 } 522 return result; 523 } 524 525 void ParallelCompactData::add_obj(HeapWord* addr, size_t len) 526 { 527 const size_t obj_ofs = pointer_delta(addr, _region_start); 528 const size_t beg_region = obj_ofs >> Log2RegionSize; 529 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize; 530 531 DEBUG_ONLY(Atomic::inc(&add_obj_count);) 532 DEBUG_ONLY(Atomic::add(len, &add_obj_size);) 533 534 if (beg_region == end_region) { 535 // All in one region. 536 _region_data[beg_region].add_live_obj(len); 537 return; 538 } 539 540 // First region. 541 const size_t beg_ofs = region_offset(addr); 542 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs); 543 544 Klass* klass = ((oop)addr)->klass(); 545 // Middle regions--completely spanned by this object. 546 for (size_t region = beg_region + 1; region < end_region; ++region) { 547 _region_data[region].set_partial_obj_size(RegionSize); 548 _region_data[region].set_partial_obj_addr(addr); 549 } 550 551 // Last region. 552 const size_t end_ofs = region_offset(addr + len - 1); 553 _region_data[end_region].set_partial_obj_size(end_ofs + 1); 554 _region_data[end_region].set_partial_obj_addr(addr); 555 } 556 557 void 558 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end) 559 { 560 assert(region_offset(beg) == 0, "not RegionSize aligned"); 561 assert(region_offset(end) == 0, "not RegionSize aligned"); 562 563 size_t cur_region = addr_to_region_idx(beg); 564 const size_t end_region = addr_to_region_idx(end); 565 HeapWord* addr = beg; 566 while (cur_region < end_region) { 567 _region_data[cur_region].set_destination(addr); 568 _region_data[cur_region].set_destination_count(0); 569 _region_data[cur_region].set_source_region(cur_region); 570 _region_data[cur_region].set_data_location(addr); 571 572 // Update live_obj_size so the region appears completely full. 573 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size(); 574 _region_data[cur_region].set_live_obj_size(live_size); 575 576 ++cur_region; 577 addr += RegionSize; 578 } 579 } 580 581 // Find the point at which a space can be split and, if necessary, record the 582 // split point. 583 // 584 // If the current src region (which overflowed the destination space) doesn't 585 // have a partial object, the split point is at the beginning of the current src 586 // region (an "easy" split, no extra bookkeeping required). 587 // 588 // If the current src region has a partial object, the split point is in the 589 // region where that partial object starts (call it the split_region). If 590 // split_region has a partial object, then the split point is just after that 591 // partial object (a "hard" split where we have to record the split data and 592 // zero the partial_obj_size field). With a "hard" split, we know that the 593 // partial_obj ends within split_region because the partial object that caused 594 // the overflow starts in split_region. If split_region doesn't have a partial 595 // obj, then the split is at the beginning of split_region (another "easy" 596 // split). 597 HeapWord* 598 ParallelCompactData::summarize_split_space(size_t src_region, 599 SplitInfo& split_info, 600 HeapWord* destination, 601 HeapWord* target_end, 602 HeapWord** target_next) 603 { 604 assert(destination <= target_end, "sanity"); 605 assert(destination + _region_data[src_region].data_size() > target_end, 606 "region should not fit into target space"); 607 assert(is_region_aligned(target_end), "sanity"); 608 609 size_t split_region = src_region; 610 HeapWord* split_destination = destination; 611 size_t partial_obj_size = _region_data[src_region].partial_obj_size(); 612 613 if (destination + partial_obj_size > target_end) { 614 // The split point is just after the partial object (if any) in the 615 // src_region that contains the start of the object that overflowed the 616 // destination space. 617 // 618 // Find the start of the "overflow" object and set split_region to the 619 // region containing it. 620 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr(); 621 split_region = addr_to_region_idx(overflow_obj); 622 623 // Clear the source_region field of all destination regions whose first word 624 // came from data after the split point (a non-null source_region field 625 // implies a region must be filled). 626 // 627 // An alternative to the simple loop below: clear during post_compact(), 628 // which uses memcpy instead of individual stores, and is easy to 629 // parallelize. (The downside is that it clears the entire RegionData 630 // object as opposed to just one field.) 631 // 632 // post_compact() would have to clear the summary data up to the highest 633 // address that was written during the summary phase, which would be 634 // 635 // max(top, max(new_top, clear_top)) 636 // 637 // where clear_top is a new field in SpaceInfo. Would have to set clear_top 638 // to target_end. 639 const RegionData* const sr = region(split_region); 640 const size_t beg_idx = 641 addr_to_region_idx(region_align_up(sr->destination() + 642 sr->partial_obj_size())); 643 const size_t end_idx = addr_to_region_idx(target_end); 644 645 log_develop_trace(gc, compaction)("split: clearing source_region field in [" SIZE_FORMAT ", " SIZE_FORMAT ")", beg_idx, end_idx); 646 for (size_t idx = beg_idx; idx < end_idx; ++idx) { 647 _region_data[idx].set_source_region(0); 648 } 649 650 // Set split_destination and partial_obj_size to reflect the split region. 651 split_destination = sr->destination(); 652 partial_obj_size = sr->partial_obj_size(); 653 } 654 655 // The split is recorded only if a partial object extends onto the region. 656 if (partial_obj_size != 0) { 657 _region_data[split_region].set_partial_obj_size(0); 658 split_info.record(split_region, partial_obj_size, split_destination); 659 } 660 661 // Setup the continuation addresses. 662 *target_next = split_destination + partial_obj_size; 663 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size; 664 665 if (log_develop_is_enabled(Trace, gc, compaction)) { 666 const char * split_type = partial_obj_size == 0 ? "easy" : "hard"; 667 log_develop_trace(gc, compaction)("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT " pos=" SIZE_FORMAT, 668 split_type, p2i(source_next), split_region, partial_obj_size); 669 log_develop_trace(gc, compaction)("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT " tn=" PTR_FORMAT, 670 split_type, p2i(split_destination), 671 addr_to_region_idx(split_destination), 672 p2i(*target_next)); 673 674 if (partial_obj_size != 0) { 675 HeapWord* const po_beg = split_info.destination(); 676 HeapWord* const po_end = po_beg + split_info.partial_obj_size(); 677 log_develop_trace(gc, compaction)("%s split: po_beg=" PTR_FORMAT " " SIZE_FORMAT " po_end=" PTR_FORMAT " " SIZE_FORMAT, 678 split_type, 679 p2i(po_beg), addr_to_region_idx(po_beg), 680 p2i(po_end), addr_to_region_idx(po_end)); 681 } 682 } 683 684 return source_next; 685 } 686 687 bool ParallelCompactData::summarize(SplitInfo& split_info, 688 HeapWord* source_beg, HeapWord* source_end, 689 HeapWord** source_next, 690 HeapWord* target_beg, HeapWord* target_end, 691 HeapWord** target_next) 692 { 693 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next; 694 log_develop_trace(gc, compaction)( 695 "sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT 696 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT, 697 p2i(source_beg), p2i(source_end), p2i(source_next_val), 698 p2i(target_beg), p2i(target_end), p2i(*target_next)); 699 700 size_t cur_region = addr_to_region_idx(source_beg); 701 const size_t end_region = addr_to_region_idx(region_align_up(source_end)); 702 703 HeapWord *dest_addr = target_beg; 704 while (cur_region < end_region) { 705 // The destination must be set even if the region has no data. 706 _region_data[cur_region].set_destination(dest_addr); 707 708 size_t words = _region_data[cur_region].data_size(); 709 if (words > 0) { 710 // If cur_region does not fit entirely into the target space, find a point 711 // at which the source space can be 'split' so that part is copied to the 712 // target space and the rest is copied elsewhere. 713 if (dest_addr + words > target_end) { 714 assert(source_next != NULL, "source_next is NULL when splitting"); 715 *source_next = summarize_split_space(cur_region, split_info, dest_addr, 716 target_end, target_next); 717 return false; 718 } 719 720 // Compute the destination_count for cur_region, and if necessary, update 721 // source_region for a destination region. The source_region field is 722 // updated if cur_region is the first (left-most) region to be copied to a 723 // destination region. 724 // 725 // The destination_count calculation is a bit subtle. A region that has 726 // data that compacts into itself does not count itself as a destination. 727 // This maintains the invariant that a zero count means the region is 728 // available and can be claimed and then filled. 729 uint destination_count = 0; 730 if (split_info.is_split(cur_region)) { 731 // The current region has been split: the partial object will be copied 732 // to one destination space and the remaining data will be copied to 733 // another destination space. Adjust the initial destination_count and, 734 // if necessary, set the source_region field if the partial object will 735 // cross a destination region boundary. 736 destination_count = split_info.destination_count(); 737 if (destination_count == 2) { 738 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr()); 739 _region_data[dest_idx].set_source_region(cur_region); 740 } 741 } 742 743 HeapWord* const last_addr = dest_addr + words - 1; 744 const size_t dest_region_1 = addr_to_region_idx(dest_addr); 745 const size_t dest_region_2 = addr_to_region_idx(last_addr); 746 747 // Initially assume that the destination regions will be the same and 748 // adjust the value below if necessary. Under this assumption, if 749 // cur_region == dest_region_2, then cur_region will be compacted 750 // completely into itself. 751 destination_count += cur_region == dest_region_2 ? 0 : 1; 752 if (dest_region_1 != dest_region_2) { 753 // Destination regions differ; adjust destination_count. 754 destination_count += 1; 755 // Data from cur_region will be copied to the start of dest_region_2. 756 _region_data[dest_region_2].set_source_region(cur_region); 757 } else if (region_offset(dest_addr) == 0) { 758 // Data from cur_region will be copied to the start of the destination 759 // region. 760 _region_data[dest_region_1].set_source_region(cur_region); 761 } 762 763 _region_data[cur_region].set_destination_count(destination_count); 764 _region_data[cur_region].set_data_location(region_to_addr(cur_region)); 765 dest_addr += words; 766 } 767 768 ++cur_region; 769 } 770 771 *target_next = dest_addr; 772 return true; 773 } 774 775 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr, ParCompactionManager* cm) { 776 assert(addr != NULL, "Should detect NULL oop earlier"); 777 assert(ParallelScavengeHeap::heap()->is_in(addr), "not in heap"); 778 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked"); 779 780 // Region covering the object. 781 RegionData* const region_ptr = addr_to_region_ptr(addr); 782 HeapWord* result = region_ptr->destination(); 783 784 // If the entire Region is live, the new location is region->destination + the 785 // offset of the object within in the Region. 786 787 // Run some performance tests to determine if this special case pays off. It 788 // is worth it for pointers into the dense prefix. If the optimization to 789 // avoid pointer updates in regions that only point to the dense prefix is 790 // ever implemented, this should be revisited. 791 if (region_ptr->data_size() == RegionSize) { 792 result += region_offset(addr); 793 return result; 794 } 795 796 // Otherwise, the new location is region->destination + block offset + the 797 // number of live words in the Block that are (a) to the left of addr and (b) 798 // due to objects that start in the Block. 799 800 // Fill in the block table if necessary. This is unsynchronized, so multiple 801 // threads may fill the block table for a region (harmless, since it is 802 // idempotent). 803 if (!region_ptr->blocks_filled()) { 804 PSParallelCompact::fill_blocks(addr_to_region_idx(addr)); 805 region_ptr->set_blocks_filled(); 806 } 807 808 HeapWord* const search_start = block_align_down(addr); 809 const size_t block_offset = addr_to_block_ptr(addr)->offset(); 810 811 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap(); 812 const size_t live = bitmap->live_words_in_range(cm, search_start, oop(addr)); 813 result += block_offset + live; 814 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result)); 815 return result; 816 } 817 818 #ifdef ASSERT 819 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace) 820 { 821 const size_t* const beg = (const size_t*)vspace->committed_low_addr(); 822 const size_t* const end = (const size_t*)vspace->committed_high_addr(); 823 for (const size_t* p = beg; p < end; ++p) { 824 assert(*p == 0, "not zero"); 825 } 826 } 827 828 void ParallelCompactData::verify_clear() 829 { 830 verify_clear(_region_vspace); 831 verify_clear(_block_vspace); 832 } 833 #endif // #ifdef ASSERT 834 835 STWGCTimer PSParallelCompact::_gc_timer; 836 ParallelOldTracer PSParallelCompact::_gc_tracer; 837 elapsedTimer PSParallelCompact::_accumulated_time; 838 unsigned int PSParallelCompact::_total_invocations = 0; 839 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0; 840 jlong PSParallelCompact::_time_of_last_gc = 0; 841 CollectorCounters* PSParallelCompact::_counters = NULL; 842 ParMarkBitMap PSParallelCompact::_mark_bitmap; 843 ParallelCompactData PSParallelCompact::_summary_data; 844 845 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure; 846 847 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); } 848 849 class PCReferenceProcessor: public ReferenceProcessor { 850 public: 851 PCReferenceProcessor( 852 BoolObjectClosure* is_subject_to_discovery, 853 BoolObjectClosure* is_alive_non_header) : 854 ReferenceProcessor(is_subject_to_discovery, 855 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing 856 ParallelGCThreads, // mt processing degree 857 true, // mt discovery 858 ParallelGCThreads, // mt discovery degree 859 true, // atomic_discovery 860 is_alive_non_header) { 861 } 862 863 template<typename T> bool discover(oop obj, ReferenceType type) { 864 T* referent_addr = (T*) java_lang_ref_Reference::referent_addr_raw(obj); 865 T heap_oop = RawAccess<>::oop_load(referent_addr); 866 oop referent = CompressedOops::decode_not_null(heap_oop); 867 return PSParallelCompact::mark_bitmap()->is_unmarked(referent) 868 && ReferenceProcessor::discover_reference(obj, type); 869 } 870 virtual bool discover_reference(oop obj, ReferenceType type) { 871 if (UseCompressedOops) { 872 return discover<narrowOop>(obj, type); 873 } else { 874 return discover<oop>(obj, type); 875 } 876 } 877 }; 878 879 void PSParallelCompact::post_initialize() { 880 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 881 _span_based_discoverer.set_span(heap->reserved_region()); 882 _ref_processor = 883 new PCReferenceProcessor(&_span_based_discoverer, 884 &_is_alive_closure); // non-header is alive closure 885 886 _counters = new CollectorCounters("PSParallelCompact", 1); 887 888 // Initialize static fields in ParCompactionManager. 889 ParCompactionManager::initialize(mark_bitmap()); 890 } 891 892 bool PSParallelCompact::initialize() { 893 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 894 MemRegion mr = heap->reserved_region(); 895 896 // Was the old gen get allocated successfully? 897 if (!heap->old_gen()->is_allocated()) { 898 return false; 899 } 900 901 initialize_space_info(); 902 initialize_dead_wood_limiter(); 903 904 if (!_mark_bitmap.initialize(mr)) { 905 vm_shutdown_during_initialization( 906 err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel " 907 "garbage collection for the requested " SIZE_FORMAT "KB heap.", 908 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K)); 909 return false; 910 } 911 912 if (!_summary_data.initialize(mr)) { 913 vm_shutdown_during_initialization( 914 err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel " 915 "garbage collection for the requested " SIZE_FORMAT "KB heap.", 916 _summary_data.reserved_byte_size()/K, mr.byte_size()/K)); 917 return false; 918 } 919 920 return true; 921 } 922 923 void PSParallelCompact::initialize_space_info() 924 { 925 memset(&_space_info, 0, sizeof(_space_info)); 926 927 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 928 PSYoungGen* young_gen = heap->young_gen(); 929 930 _space_info[old_space_id].set_space(heap->old_gen()->object_space()); 931 _space_info[eden_space_id].set_space(young_gen->eden_space()); 932 _space_info[from_space_id].set_space(young_gen->from_space()); 933 _space_info[to_space_id].set_space(young_gen->to_space()); 934 935 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array()); 936 } 937 938 void PSParallelCompact::initialize_dead_wood_limiter() 939 { 940 const size_t max = 100; 941 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0; 942 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0; 943 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev); 944 DEBUG_ONLY(_dwl_initialized = true;) 945 _dwl_adjustment = normal_distribution(1.0); 946 } 947 948 void 949 PSParallelCompact::clear_data_covering_space(SpaceId id) 950 { 951 // At this point, top is the value before GC, new_top() is the value that will 952 // be set at the end of GC. The marking bitmap is cleared to top; nothing 953 // should be marked above top. The summary data is cleared to the larger of 954 // top & new_top. 955 MutableSpace* const space = _space_info[id].space(); 956 HeapWord* const bot = space->bottom(); 957 HeapWord* const top = space->top(); 958 HeapWord* const max_top = MAX2(top, _space_info[id].new_top()); 959 960 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot); 961 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top)); 962 _mark_bitmap.clear_range(beg_bit, end_bit); 963 964 const size_t beg_region = _summary_data.addr_to_region_idx(bot); 965 const size_t end_region = 966 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top)); 967 _summary_data.clear_range(beg_region, end_region); 968 969 // Clear the data used to 'split' regions. 970 SplitInfo& split_info = _space_info[id].split_info(); 971 if (split_info.is_valid()) { 972 split_info.clear(); 973 } 974 DEBUG_ONLY(split_info.verify_clear();) 975 } 976 977 void PSParallelCompact::pre_compact() 978 { 979 // Update the from & to space pointers in space_info, since they are swapped 980 // at each young gen gc. Do the update unconditionally (even though a 981 // promotion failure does not swap spaces) because an unknown number of young 982 // collections will have swapped the spaces an unknown number of times. 983 GCTraceTime(Debug, gc, phases) tm("Pre Compact", &_gc_timer); 984 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 985 _space_info[from_space_id].set_space(heap->young_gen()->from_space()); 986 _space_info[to_space_id].set_space(heap->young_gen()->to_space()); 987 988 DEBUG_ONLY(add_obj_count = add_obj_size = 0;) 989 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;) 990 991 // Increment the invocation count 992 heap->increment_total_collections(true); 993 994 // We need to track unique mark sweep invocations as well. 995 _total_invocations++; 996 997 heap->print_heap_before_gc(); 998 heap->trace_heap_before_gc(&_gc_tracer); 999 1000 // Fill in TLABs 1001 heap->ensure_parsability(true); // retire TLABs 1002 1003 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 1004 HandleMark hm; // Discard invalid handles created during verification 1005 Universe::verify("Before GC"); 1006 } 1007 1008 // Verify object start arrays 1009 if (VerifyObjectStartArray && 1010 VerifyBeforeGC) { 1011 heap->old_gen()->verify_object_start_array(); 1012 } 1013 1014 DEBUG_ONLY(mark_bitmap()->verify_clear();) 1015 DEBUG_ONLY(summary_data().verify_clear();) 1016 1017 // Have worker threads release resources the next time they run a task. 1018 gc_task_manager()->release_all_resources(); 1019 1020 ParCompactionManager::reset_all_bitmap_query_caches(); 1021 } 1022 1023 void PSParallelCompact::post_compact() 1024 { 1025 GCTraceTime(Info, gc, phases) tm("Post Compact", &_gc_timer); 1026 1027 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 1028 // Clear the marking bitmap, summary data and split info. 1029 clear_data_covering_space(SpaceId(id)); 1030 // Update top(). Must be done after clearing the bitmap and summary data. 1031 _space_info[id].publish_new_top(); 1032 } 1033 1034 MutableSpace* const eden_space = _space_info[eden_space_id].space(); 1035 MutableSpace* const from_space = _space_info[from_space_id].space(); 1036 MutableSpace* const to_space = _space_info[to_space_id].space(); 1037 1038 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 1039 bool eden_empty = eden_space->is_empty(); 1040 if (!eden_empty) { 1041 eden_empty = absorb_live_data_from_eden(heap->size_policy(), 1042 heap->young_gen(), heap->old_gen()); 1043 } 1044 1045 // Update heap occupancy information which is used as input to the soft ref 1046 // clearing policy at the next gc. 1047 Universe::update_heap_info_at_gc(); 1048 1049 bool young_gen_empty = eden_empty && from_space->is_empty() && 1050 to_space->is_empty(); 1051 1052 PSCardTable* ct = heap->card_table(); 1053 MemRegion old_mr = heap->old_gen()->reserved(); 1054 if (young_gen_empty) { 1055 ct->clear(MemRegion(old_mr.start(), old_mr.end())); 1056 } else { 1057 ct->invalidate(MemRegion(old_mr.start(), old_mr.end())); 1058 } 1059 1060 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1061 ClassLoaderDataGraph::purge(); 1062 MetaspaceUtils::verify_metrics(); 1063 1064 CodeCache::gc_epilogue(); 1065 JvmtiExport::gc_epilogue(); 1066 1067 #if COMPILER2_OR_JVMCI 1068 DerivedPointerTable::update_pointers(); 1069 #endif 1070 1071 if (ZapUnusedHeapArea) { 1072 heap->gen_mangle_unused_area(); 1073 } 1074 1075 // Update time of last GC 1076 reset_millis_since_last_gc(); 1077 } 1078 1079 HeapWord* 1080 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id, 1081 bool maximum_compaction) 1082 { 1083 const size_t region_size = ParallelCompactData::RegionSize; 1084 const ParallelCompactData& sd = summary_data(); 1085 1086 const MutableSpace* const space = _space_info[id].space(); 1087 HeapWord* const top_aligned_up = sd.region_align_up(space->top()); 1088 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom()); 1089 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up); 1090 1091 // Skip full regions at the beginning of the space--they are necessarily part 1092 // of the dense prefix. 1093 size_t full_count = 0; 1094 const RegionData* cp; 1095 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) { 1096 ++full_count; 1097 } 1098 1099 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity"); 1100 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num; 1101 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval; 1102 if (maximum_compaction || cp == end_cp || interval_ended) { 1103 _maximum_compaction_gc_num = total_invocations(); 1104 return sd.region_to_addr(cp); 1105 } 1106 1107 HeapWord* const new_top = _space_info[id].new_top(); 1108 const size_t space_live = pointer_delta(new_top, space->bottom()); 1109 const size_t space_used = space->used_in_words(); 1110 const size_t space_capacity = space->capacity_in_words(); 1111 1112 const double cur_density = double(space_live) / space_capacity; 1113 const double deadwood_density = 1114 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density; 1115 const size_t deadwood_goal = size_t(space_capacity * deadwood_density); 1116 1117 if (TraceParallelOldGCDensePrefix) { 1118 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT, 1119 cur_density, deadwood_density, deadwood_goal); 1120 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " " 1121 "space_cap=" SIZE_FORMAT, 1122 space_live, space_used, 1123 space_capacity); 1124 } 1125 1126 // XXX - Use binary search? 1127 HeapWord* dense_prefix = sd.region_to_addr(cp); 1128 const RegionData* full_cp = cp; 1129 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1); 1130 while (cp < end_cp) { 1131 HeapWord* region_destination = cp->destination(); 1132 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination); 1133 if (TraceParallelOldGCDensePrefix && Verbose) { 1134 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " " 1135 "dp=" PTR_FORMAT " " "cdw=" SIZE_FORMAT_W(8), 1136 sd.region(cp), p2i(region_destination), 1137 p2i(dense_prefix), cur_deadwood); 1138 } 1139 1140 if (cur_deadwood >= deadwood_goal) { 1141 // Found the region that has the correct amount of deadwood to the left. 1142 // This typically occurs after crossing a fairly sparse set of regions, so 1143 // iterate backwards over those sparse regions, looking for the region 1144 // that has the lowest density of live objects 'to the right.' 1145 size_t space_to_left = sd.region(cp) * region_size; 1146 size_t live_to_left = space_to_left - cur_deadwood; 1147 size_t space_to_right = space_capacity - space_to_left; 1148 size_t live_to_right = space_live - live_to_left; 1149 double density_to_right = double(live_to_right) / space_to_right; 1150 while (cp > full_cp) { 1151 --cp; 1152 const size_t prev_region_live_to_right = live_to_right - 1153 cp->data_size(); 1154 const size_t prev_region_space_to_right = space_to_right + region_size; 1155 double prev_region_density_to_right = 1156 double(prev_region_live_to_right) / prev_region_space_to_right; 1157 if (density_to_right <= prev_region_density_to_right) { 1158 return dense_prefix; 1159 } 1160 if (TraceParallelOldGCDensePrefix && Verbose) { 1161 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f " 1162 "pc_d2r=%10.8f", sd.region(cp), density_to_right, 1163 prev_region_density_to_right); 1164 } 1165 dense_prefix -= region_size; 1166 live_to_right = prev_region_live_to_right; 1167 space_to_right = prev_region_space_to_right; 1168 density_to_right = prev_region_density_to_right; 1169 } 1170 return dense_prefix; 1171 } 1172 1173 dense_prefix += region_size; 1174 ++cp; 1175 } 1176 1177 return dense_prefix; 1178 } 1179 1180 #ifndef PRODUCT 1181 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm, 1182 const SpaceId id, 1183 const bool maximum_compaction, 1184 HeapWord* const addr) 1185 { 1186 const size_t region_idx = summary_data().addr_to_region_idx(addr); 1187 RegionData* const cp = summary_data().region(region_idx); 1188 const MutableSpace* const space = _space_info[id].space(); 1189 HeapWord* const new_top = _space_info[id].new_top(); 1190 1191 const size_t space_live = pointer_delta(new_top, space->bottom()); 1192 const size_t dead_to_left = pointer_delta(addr, cp->destination()); 1193 const size_t space_cap = space->capacity_in_words(); 1194 const double dead_to_left_pct = double(dead_to_left) / space_cap; 1195 const size_t live_to_right = new_top - cp->destination(); 1196 const size_t dead_to_right = space->top() - addr - live_to_right; 1197 1198 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " " 1199 "spl=" SIZE_FORMAT " " 1200 "d2l=" SIZE_FORMAT " d2l%%=%6.4f " 1201 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT 1202 " ratio=%10.8f", 1203 algorithm, p2i(addr), region_idx, 1204 space_live, 1205 dead_to_left, dead_to_left_pct, 1206 dead_to_right, live_to_right, 1207 double(dead_to_right) / live_to_right); 1208 } 1209 #endif // #ifndef PRODUCT 1210 1211 // Return a fraction indicating how much of the generation can be treated as 1212 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution 1213 // based on the density of live objects in the generation to determine a limit, 1214 // which is then adjusted so the return value is min_percent when the density is 1215 // 1. 1216 // 1217 // The following table shows some return values for a different values of the 1218 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and 1219 // min_percent is 1. 1220 // 1221 // fraction allowed as dead wood 1222 // ----------------------------------------------------------------- 1223 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95 1224 // ------- ---------- ---------- ---------- ---------- ---------- ---------- 1225 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 1226 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941 1227 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272 1228 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066 1229 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975 1230 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313 1231 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132 1232 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289 1233 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500 1234 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386 1235 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510 1236 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386 1237 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500 1238 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289 1239 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132 1240 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313 1241 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975 1242 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066 1243 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272 1244 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941 1245 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 1246 1247 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent) 1248 { 1249 assert(_dwl_initialized, "uninitialized"); 1250 1251 // The raw limit is the value of the normal distribution at x = density. 1252 const double raw_limit = normal_distribution(density); 1253 1254 // Adjust the raw limit so it becomes the minimum when the density is 1. 1255 // 1256 // First subtract the adjustment value (which is simply the precomputed value 1257 // normal_distribution(1.0)); this yields a value of 0 when the density is 1. 1258 // Then add the minimum value, so the minimum is returned when the density is 1259 // 1. Finally, prevent negative values, which occur when the mean is not 0.5. 1260 const double min = double(min_percent) / 100.0; 1261 const double limit = raw_limit - _dwl_adjustment + min; 1262 return MAX2(limit, 0.0); 1263 } 1264 1265 ParallelCompactData::RegionData* 1266 PSParallelCompact::first_dead_space_region(const RegionData* beg, 1267 const RegionData* end) 1268 { 1269 const size_t region_size = ParallelCompactData::RegionSize; 1270 ParallelCompactData& sd = summary_data(); 1271 size_t left = sd.region(beg); 1272 size_t right = end > beg ? sd.region(end) - 1 : left; 1273 1274 // Binary search. 1275 while (left < right) { 1276 // Equivalent to (left + right) / 2, but does not overflow. 1277 const size_t middle = left + (right - left) / 2; 1278 RegionData* const middle_ptr = sd.region(middle); 1279 HeapWord* const dest = middle_ptr->destination(); 1280 HeapWord* const addr = sd.region_to_addr(middle); 1281 assert(dest != NULL, "sanity"); 1282 assert(dest <= addr, "must move left"); 1283 1284 if (middle > left && dest < addr) { 1285 right = middle - 1; 1286 } else if (middle < right && middle_ptr->data_size() == region_size) { 1287 left = middle + 1; 1288 } else { 1289 return middle_ptr; 1290 } 1291 } 1292 return sd.region(left); 1293 } 1294 1295 ParallelCompactData::RegionData* 1296 PSParallelCompact::dead_wood_limit_region(const RegionData* beg, 1297 const RegionData* end, 1298 size_t dead_words) 1299 { 1300 ParallelCompactData& sd = summary_data(); 1301 size_t left = sd.region(beg); 1302 size_t right = end > beg ? sd.region(end) - 1 : left; 1303 1304 // Binary search. 1305 while (left < right) { 1306 // Equivalent to (left + right) / 2, but does not overflow. 1307 const size_t middle = left + (right - left) / 2; 1308 RegionData* const middle_ptr = sd.region(middle); 1309 HeapWord* const dest = middle_ptr->destination(); 1310 HeapWord* const addr = sd.region_to_addr(middle); 1311 assert(dest != NULL, "sanity"); 1312 assert(dest <= addr, "must move left"); 1313 1314 const size_t dead_to_left = pointer_delta(addr, dest); 1315 if (middle > left && dead_to_left > dead_words) { 1316 right = middle - 1; 1317 } else if (middle < right && dead_to_left < dead_words) { 1318 left = middle + 1; 1319 } else { 1320 return middle_ptr; 1321 } 1322 } 1323 return sd.region(left); 1324 } 1325 1326 // The result is valid during the summary phase, after the initial summarization 1327 // of each space into itself, and before final summarization. 1328 inline double 1329 PSParallelCompact::reclaimed_ratio(const RegionData* const cp, 1330 HeapWord* const bottom, 1331 HeapWord* const top, 1332 HeapWord* const new_top) 1333 { 1334 ParallelCompactData& sd = summary_data(); 1335 1336 assert(cp != NULL, "sanity"); 1337 assert(bottom != NULL, "sanity"); 1338 assert(top != NULL, "sanity"); 1339 assert(new_top != NULL, "sanity"); 1340 assert(top >= new_top, "summary data problem?"); 1341 assert(new_top > bottom, "space is empty; should not be here"); 1342 assert(new_top >= cp->destination(), "sanity"); 1343 assert(top >= sd.region_to_addr(cp), "sanity"); 1344 1345 HeapWord* const destination = cp->destination(); 1346 const size_t dense_prefix_live = pointer_delta(destination, bottom); 1347 const size_t compacted_region_live = pointer_delta(new_top, destination); 1348 const size_t compacted_region_used = pointer_delta(top, 1349 sd.region_to_addr(cp)); 1350 const size_t reclaimable = compacted_region_used - compacted_region_live; 1351 1352 const double divisor = dense_prefix_live + 1.25 * compacted_region_live; 1353 return double(reclaimable) / divisor; 1354 } 1355 1356 // Return the address of the end of the dense prefix, a.k.a. the start of the 1357 // compacted region. The address is always on a region boundary. 1358 // 1359 // Completely full regions at the left are skipped, since no compaction can 1360 // occur in those regions. Then the maximum amount of dead wood to allow is 1361 // computed, based on the density (amount live / capacity) of the generation; 1362 // the region with approximately that amount of dead space to the left is 1363 // identified as the limit region. Regions between the last completely full 1364 // region and the limit region are scanned and the one that has the best 1365 // (maximum) reclaimed_ratio() is selected. 1366 HeapWord* 1367 PSParallelCompact::compute_dense_prefix(const SpaceId id, 1368 bool maximum_compaction) 1369 { 1370 const size_t region_size = ParallelCompactData::RegionSize; 1371 const ParallelCompactData& sd = summary_data(); 1372 1373 const MutableSpace* const space = _space_info[id].space(); 1374 HeapWord* const top = space->top(); 1375 HeapWord* const top_aligned_up = sd.region_align_up(top); 1376 HeapWord* const new_top = _space_info[id].new_top(); 1377 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top); 1378 HeapWord* const bottom = space->bottom(); 1379 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom); 1380 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up); 1381 const RegionData* const new_top_cp = 1382 sd.addr_to_region_ptr(new_top_aligned_up); 1383 1384 // Skip full regions at the beginning of the space--they are necessarily part 1385 // of the dense prefix. 1386 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp); 1387 assert(full_cp->destination() == sd.region_to_addr(full_cp) || 1388 space->is_empty(), "no dead space allowed to the left"); 1389 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1, 1390 "region must have dead space"); 1391 1392 // The gc number is saved whenever a maximum compaction is done, and used to 1393 // determine when the maximum compaction interval has expired. This avoids 1394 // successive max compactions for different reasons. 1395 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity"); 1396 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num; 1397 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval || 1398 total_invocations() == HeapFirstMaximumCompactionCount; 1399 if (maximum_compaction || full_cp == top_cp || interval_ended) { 1400 _maximum_compaction_gc_num = total_invocations(); 1401 return sd.region_to_addr(full_cp); 1402 } 1403 1404 const size_t space_live = pointer_delta(new_top, bottom); 1405 const size_t space_used = space->used_in_words(); 1406 const size_t space_capacity = space->capacity_in_words(); 1407 1408 const double density = double(space_live) / double(space_capacity); 1409 const size_t min_percent_free = MarkSweepDeadRatio; 1410 const double limiter = dead_wood_limiter(density, min_percent_free); 1411 const size_t dead_wood_max = space_used - space_live; 1412 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter), 1413 dead_wood_max); 1414 1415 if (TraceParallelOldGCDensePrefix) { 1416 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " " 1417 "space_cap=" SIZE_FORMAT, 1418 space_live, space_used, 1419 space_capacity); 1420 tty->print_cr("dead_wood_limiter(%6.4f, " SIZE_FORMAT ")=%6.4f " 1421 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT, 1422 density, min_percent_free, limiter, 1423 dead_wood_max, dead_wood_limit); 1424 } 1425 1426 // Locate the region with the desired amount of dead space to the left. 1427 const RegionData* const limit_cp = 1428 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit); 1429 1430 // Scan from the first region with dead space to the limit region and find the 1431 // one with the best (largest) reclaimed ratio. 1432 double best_ratio = 0.0; 1433 const RegionData* best_cp = full_cp; 1434 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) { 1435 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top); 1436 if (tmp_ratio > best_ratio) { 1437 best_cp = cp; 1438 best_ratio = tmp_ratio; 1439 } 1440 } 1441 1442 return sd.region_to_addr(best_cp); 1443 } 1444 1445 void PSParallelCompact::summarize_spaces_quick() 1446 { 1447 for (unsigned int i = 0; i < last_space_id; ++i) { 1448 const MutableSpace* space = _space_info[i].space(); 1449 HeapWord** nta = _space_info[i].new_top_addr(); 1450 bool result = _summary_data.summarize(_space_info[i].split_info(), 1451 space->bottom(), space->top(), NULL, 1452 space->bottom(), space->end(), nta); 1453 assert(result, "space must fit into itself"); 1454 _space_info[i].set_dense_prefix(space->bottom()); 1455 } 1456 } 1457 1458 void PSParallelCompact::fill_dense_prefix_end(SpaceId id) 1459 { 1460 HeapWord* const dense_prefix_end = dense_prefix(id); 1461 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end); 1462 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end); 1463 if (dead_space_crosses_boundary(region, dense_prefix_bit)) { 1464 // Only enough dead space is filled so that any remaining dead space to the 1465 // left is larger than the minimum filler object. (The remainder is filled 1466 // during the copy/update phase.) 1467 // 1468 // The size of the dead space to the right of the boundary is not a 1469 // concern, since compaction will be able to use whatever space is 1470 // available. 1471 // 1472 // Here '||' is the boundary, 'x' represents a don't care bit and a box 1473 // surrounds the space to be filled with an object. 1474 // 1475 // In the 32-bit VM, each bit represents two 32-bit words: 1476 // +---+ 1477 // a) beg_bits: ... x x x | 0 | || 0 x x ... 1478 // end_bits: ... x x x | 0 | || 0 x x ... 1479 // +---+ 1480 // 1481 // In the 64-bit VM, each bit represents one 64-bit word: 1482 // +------------+ 1483 // b) beg_bits: ... x x x | 0 || 0 | x x ... 1484 // end_bits: ... x x 1 | 0 || 0 | x x ... 1485 // +------------+ 1486 // +-------+ 1487 // c) beg_bits: ... x x | 0 0 | || 0 x x ... 1488 // end_bits: ... x 1 | 0 0 | || 0 x x ... 1489 // +-------+ 1490 // +-----------+ 1491 // d) beg_bits: ... x | 0 0 0 | || 0 x x ... 1492 // end_bits: ... 1 | 0 0 0 | || 0 x x ... 1493 // +-----------+ 1494 // +-------+ 1495 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ... 1496 // end_bits: ... 0 0 | 0 0 | || 0 x x ... 1497 // +-------+ 1498 1499 // Initially assume case a, c or e will apply. 1500 size_t obj_len = CollectedHeap::min_fill_size(); 1501 HeapWord* obj_beg = dense_prefix_end - obj_len; 1502 1503 #ifdef _LP64 1504 if (MinObjAlignment > 1) { // object alignment > heap word size 1505 // Cases a, c or e. 1506 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) { 1507 // Case b above. 1508 obj_beg = dense_prefix_end - 1; 1509 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) && 1510 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) { 1511 // Case d above. 1512 obj_beg = dense_prefix_end - 3; 1513 obj_len = 3; 1514 } 1515 #endif // #ifdef _LP64 1516 1517 CollectedHeap::fill_with_object(obj_beg, obj_len); 1518 _mark_bitmap.mark_obj(obj_beg, obj_len); 1519 _summary_data.add_obj(obj_beg, obj_len); 1520 assert(start_array(id) != NULL, "sanity"); 1521 start_array(id)->allocate_block(obj_beg); 1522 } 1523 } 1524 1525 void 1526 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction) 1527 { 1528 assert(id < last_space_id, "id out of range"); 1529 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(), 1530 "should have been reset in summarize_spaces_quick()"); 1531 1532 const MutableSpace* space = _space_info[id].space(); 1533 if (_space_info[id].new_top() != space->bottom()) { 1534 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction); 1535 _space_info[id].set_dense_prefix(dense_prefix_end); 1536 1537 #ifndef PRODUCT 1538 if (TraceParallelOldGCDensePrefix) { 1539 print_dense_prefix_stats("ratio", id, maximum_compaction, 1540 dense_prefix_end); 1541 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction); 1542 print_dense_prefix_stats("density", id, maximum_compaction, addr); 1543 } 1544 #endif // #ifndef PRODUCT 1545 1546 // Recompute the summary data, taking into account the dense prefix. If 1547 // every last byte will be reclaimed, then the existing summary data which 1548 // compacts everything can be left in place. 1549 if (!maximum_compaction && dense_prefix_end != space->bottom()) { 1550 // If dead space crosses the dense prefix boundary, it is (at least 1551 // partially) filled with a dummy object, marked live and added to the 1552 // summary data. This simplifies the copy/update phase and must be done 1553 // before the final locations of objects are determined, to prevent 1554 // leaving a fragment of dead space that is too small to fill. 1555 fill_dense_prefix_end(id); 1556 1557 // Compute the destination of each Region, and thus each object. 1558 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end); 1559 _summary_data.summarize(_space_info[id].split_info(), 1560 dense_prefix_end, space->top(), NULL, 1561 dense_prefix_end, space->end(), 1562 _space_info[id].new_top_addr()); 1563 } 1564 } 1565 1566 if (log_develop_is_enabled(Trace, gc, compaction)) { 1567 const size_t region_size = ParallelCompactData::RegionSize; 1568 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix(); 1569 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end); 1570 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom()); 1571 HeapWord* const new_top = _space_info[id].new_top(); 1572 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top); 1573 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end); 1574 log_develop_trace(gc, compaction)( 1575 "id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " " 1576 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " " 1577 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT, 1578 id, space->capacity_in_words(), p2i(dense_prefix_end), 1579 dp_region, dp_words / region_size, 1580 cr_words / region_size, p2i(new_top)); 1581 } 1582 } 1583 1584 #ifndef PRODUCT 1585 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id, 1586 HeapWord* dst_beg, HeapWord* dst_end, 1587 SpaceId src_space_id, 1588 HeapWord* src_beg, HeapWord* src_end) 1589 { 1590 log_develop_trace(gc, compaction)( 1591 "Summarizing %d [%s] into %d [%s]: " 1592 "src=" PTR_FORMAT "-" PTR_FORMAT " " 1593 SIZE_FORMAT "-" SIZE_FORMAT " " 1594 "dst=" PTR_FORMAT "-" PTR_FORMAT " " 1595 SIZE_FORMAT "-" SIZE_FORMAT, 1596 src_space_id, space_names[src_space_id], 1597 dst_space_id, space_names[dst_space_id], 1598 p2i(src_beg), p2i(src_end), 1599 _summary_data.addr_to_region_idx(src_beg), 1600 _summary_data.addr_to_region_idx(src_end), 1601 p2i(dst_beg), p2i(dst_end), 1602 _summary_data.addr_to_region_idx(dst_beg), 1603 _summary_data.addr_to_region_idx(dst_end)); 1604 } 1605 #endif // #ifndef PRODUCT 1606 1607 void PSParallelCompact::summary_phase(ParCompactionManager* cm, 1608 bool maximum_compaction) 1609 { 1610 GCTraceTime(Info, gc, phases) tm("Summary Phase", &_gc_timer); 1611 1612 #ifdef ASSERT 1613 if (TraceParallelOldGCMarkingPhase) { 1614 tty->print_cr("add_obj_count=" SIZE_FORMAT " " 1615 "add_obj_bytes=" SIZE_FORMAT, 1616 add_obj_count, add_obj_size * HeapWordSize); 1617 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " " 1618 "mark_bitmap_bytes=" SIZE_FORMAT, 1619 mark_bitmap_count, mark_bitmap_size * HeapWordSize); 1620 } 1621 #endif // #ifdef ASSERT 1622 1623 // Quick summarization of each space into itself, to see how much is live. 1624 summarize_spaces_quick(); 1625 1626 log_develop_trace(gc, compaction)("summary phase: after summarizing each space to self"); 1627 NOT_PRODUCT(print_region_ranges()); 1628 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info)); 1629 1630 // The amount of live data that will end up in old space (assuming it fits). 1631 size_t old_space_total_live = 0; 1632 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 1633 old_space_total_live += pointer_delta(_space_info[id].new_top(), 1634 _space_info[id].space()->bottom()); 1635 } 1636 1637 MutableSpace* const old_space = _space_info[old_space_id].space(); 1638 const size_t old_capacity = old_space->capacity_in_words(); 1639 if (old_space_total_live > old_capacity) { 1640 // XXX - should also try to expand 1641 maximum_compaction = true; 1642 } 1643 1644 // Old generations. 1645 summarize_space(old_space_id, maximum_compaction); 1646 1647 // Summarize the remaining spaces in the young gen. The initial target space 1648 // is the old gen. If a space does not fit entirely into the target, then the 1649 // remainder is compacted into the space itself and that space becomes the new 1650 // target. 1651 SpaceId dst_space_id = old_space_id; 1652 HeapWord* dst_space_end = old_space->end(); 1653 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr(); 1654 for (unsigned int id = eden_space_id; id < last_space_id; ++id) { 1655 const MutableSpace* space = _space_info[id].space(); 1656 const size_t live = pointer_delta(_space_info[id].new_top(), 1657 space->bottom()); 1658 const size_t available = pointer_delta(dst_space_end, *new_top_addr); 1659 1660 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end, 1661 SpaceId(id), space->bottom(), space->top());) 1662 if (live > 0 && live <= available) { 1663 // All the live data will fit. 1664 bool done = _summary_data.summarize(_space_info[id].split_info(), 1665 space->bottom(), space->top(), 1666 NULL, 1667 *new_top_addr, dst_space_end, 1668 new_top_addr); 1669 assert(done, "space must fit into old gen"); 1670 1671 // Reset the new_top value for the space. 1672 _space_info[id].set_new_top(space->bottom()); 1673 } else if (live > 0) { 1674 // Attempt to fit part of the source space into the target space. 1675 HeapWord* next_src_addr = NULL; 1676 bool done = _summary_data.summarize(_space_info[id].split_info(), 1677 space->bottom(), space->top(), 1678 &next_src_addr, 1679 *new_top_addr, dst_space_end, 1680 new_top_addr); 1681 assert(!done, "space should not fit into old gen"); 1682 assert(next_src_addr != NULL, "sanity"); 1683 1684 // The source space becomes the new target, so the remainder is compacted 1685 // within the space itself. 1686 dst_space_id = SpaceId(id); 1687 dst_space_end = space->end(); 1688 new_top_addr = _space_info[id].new_top_addr(); 1689 NOT_PRODUCT(summary_phase_msg(dst_space_id, 1690 space->bottom(), dst_space_end, 1691 SpaceId(id), next_src_addr, space->top());) 1692 done = _summary_data.summarize(_space_info[id].split_info(), 1693 next_src_addr, space->top(), 1694 NULL, 1695 space->bottom(), dst_space_end, 1696 new_top_addr); 1697 assert(done, "space must fit when compacted into itself"); 1698 assert(*new_top_addr <= space->top(), "usage should not grow"); 1699 } 1700 } 1701 1702 log_develop_trace(gc, compaction)("Summary_phase: after final summarization"); 1703 NOT_PRODUCT(print_region_ranges()); 1704 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info)); 1705 } 1706 1707 // This method should contain all heap-specific policy for invoking a full 1708 // collection. invoke_no_policy() will only attempt to compact the heap; it 1709 // will do nothing further. If we need to bail out for policy reasons, scavenge 1710 // before full gc, or any other specialized behavior, it needs to be added here. 1711 // 1712 // Note that this method should only be called from the vm_thread while at a 1713 // safepoint. 1714 // 1715 // Note that the all_soft_refs_clear flag in the collector policy 1716 // may be true because this method can be called without intervening 1717 // activity. For example when the heap space is tight and full measure 1718 // are being taken to free space. 1719 void PSParallelCompact::invoke(bool maximum_heap_compaction) { 1720 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 1721 assert(Thread::current() == (Thread*)VMThread::vm_thread(), 1722 "should be in vm thread"); 1723 1724 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 1725 GCCause::Cause gc_cause = heap->gc_cause(); 1726 assert(!heap->is_gc_active(), "not reentrant"); 1727 1728 PSAdaptiveSizePolicy* policy = heap->size_policy(); 1729 IsGCActiveMark mark; 1730 1731 if (ScavengeBeforeFullGC) { 1732 PSScavenge::invoke_no_policy(); 1733 } 1734 1735 const bool clear_all_soft_refs = 1736 heap->soft_ref_policy()->should_clear_all_soft_refs(); 1737 1738 PSParallelCompact::invoke_no_policy(clear_all_soft_refs || 1739 maximum_heap_compaction); 1740 } 1741 1742 // This method contains no policy. You should probably 1743 // be calling invoke() instead. 1744 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) { 1745 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); 1746 assert(ref_processor() != NULL, "Sanity"); 1747 1748 if (GCLocker::check_active_before_gc()) { 1749 return false; 1750 } 1751 1752 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 1753 1754 GCIdMark gc_id_mark; 1755 _gc_timer.register_gc_start(); 1756 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start()); 1757 1758 TimeStamp marking_start; 1759 TimeStamp compaction_start; 1760 TimeStamp collection_exit; 1761 1762 GCCause::Cause gc_cause = heap->gc_cause(); 1763 PSYoungGen* young_gen = heap->young_gen(); 1764 PSOldGen* old_gen = heap->old_gen(); 1765 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 1766 1767 // The scope of casr should end after code that can change 1768 // CollectorPolicy::_should_clear_all_soft_refs. 1769 ClearedAllSoftRefs casr(maximum_heap_compaction, 1770 heap->soft_ref_policy()); 1771 1772 if (ZapUnusedHeapArea) { 1773 // Save information needed to minimize mangling 1774 heap->record_gen_tops_before_GC(); 1775 } 1776 1777 // Make sure data structures are sane, make the heap parsable, and do other 1778 // miscellaneous bookkeeping. 1779 pre_compact(); 1780 1781 PreGCValues pre_gc_values(heap); 1782 1783 // Get the compaction manager reserved for the VM thread. 1784 ParCompactionManager* const vmthread_cm = 1785 ParCompactionManager::manager_array(gc_task_manager()->workers()); 1786 1787 { 1788 ResourceMark rm; 1789 HandleMark hm; 1790 1791 // Set the number of GC threads to be used in this collection 1792 gc_task_manager()->set_active_gang(); 1793 gc_task_manager()->task_idle_workers(); 1794 1795 GCTraceCPUTime tcpu; 1796 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause, true); 1797 1798 heap->pre_full_gc_dump(&_gc_timer); 1799 1800 TraceCollectorStats tcs(counters()); 1801 TraceMemoryManagerStats tms(heap->old_gc_manager(), gc_cause); 1802 1803 if (log_is_enabled(Debug, gc, heap, exit)) { 1804 accumulated_time()->start(); 1805 } 1806 1807 // Let the size policy know we're starting 1808 size_policy->major_collection_begin(); 1809 1810 CodeCache::gc_prologue(); 1811 1812 #if COMPILER2_OR_JVMCI 1813 DerivedPointerTable::clear(); 1814 #endif 1815 1816 ref_processor()->enable_discovery(); 1817 ref_processor()->setup_policy(maximum_heap_compaction); 1818 1819 bool marked_for_unloading = false; 1820 1821 marking_start.update(); 1822 marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer); 1823 1824 bool max_on_system_gc = UseMaximumCompactionOnSystemGC 1825 && GCCause::is_user_requested_gc(gc_cause); 1826 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc); 1827 1828 #if COMPILER2_OR_JVMCI 1829 assert(DerivedPointerTable::is_active(), "Sanity"); 1830 DerivedPointerTable::set_active(false); 1831 #endif 1832 1833 // adjust_roots() updates Universe::_intArrayKlassObj which is 1834 // needed by the compaction for filling holes in the dense prefix. 1835 adjust_roots(vmthread_cm); 1836 1837 compaction_start.update(); 1838 compact(); 1839 1840 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be 1841 // done before resizing. 1842 post_compact(); 1843 1844 // Let the size policy know we're done 1845 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause); 1846 1847 if (UseAdaptiveSizePolicy) { 1848 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections()); 1849 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT, 1850 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 1851 1852 // Don't check if the size_policy is ready here. Let 1853 // the size_policy check that internally. 1854 if (UseAdaptiveGenerationSizePolicyAtMajorCollection && 1855 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) { 1856 // Swap the survivor spaces if from_space is empty. The 1857 // resize_young_gen() called below is normally used after 1858 // a successful young GC and swapping of survivor spaces; 1859 // otherwise, it will fail to resize the young gen with 1860 // the current implementation. 1861 if (young_gen->from_space()->is_empty()) { 1862 young_gen->from_space()->clear(SpaceDecorator::Mangle); 1863 young_gen->swap_spaces(); 1864 } 1865 1866 // Calculate optimal free space amounts 1867 assert(young_gen->max_size() > 1868 young_gen->from_space()->capacity_in_bytes() + 1869 young_gen->to_space()->capacity_in_bytes(), 1870 "Sizes of space in young gen are out-of-bounds"); 1871 1872 size_t young_live = young_gen->used_in_bytes(); 1873 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 1874 size_t old_live = old_gen->used_in_bytes(); 1875 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 1876 size_t max_old_gen_size = old_gen->max_gen_size(); 1877 size_t max_eden_size = young_gen->max_size() - 1878 young_gen->from_space()->capacity_in_bytes() - 1879 young_gen->to_space()->capacity_in_bytes(); 1880 1881 // Used for diagnostics 1882 size_policy->clear_generation_free_space_flags(); 1883 1884 size_policy->compute_generations_free_space(young_live, 1885 eden_live, 1886 old_live, 1887 cur_eden, 1888 max_old_gen_size, 1889 max_eden_size, 1890 true /* full gc*/); 1891 1892 size_policy->check_gc_overhead_limit(young_live, 1893 eden_live, 1894 max_old_gen_size, 1895 max_eden_size, 1896 true /* full gc*/, 1897 gc_cause, 1898 heap->soft_ref_policy()); 1899 1900 size_policy->decay_supplemental_growth(true /* full gc*/); 1901 1902 heap->resize_old_gen( 1903 size_policy->calculated_old_free_size_in_bytes()); 1904 1905 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 1906 size_policy->calculated_survivor_size_in_bytes()); 1907 } 1908 1909 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections()); 1910 } 1911 1912 if (UsePerfData) { 1913 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters(); 1914 counters->update_counters(); 1915 counters->update_old_capacity(old_gen->capacity_in_bytes()); 1916 counters->update_young_capacity(young_gen->capacity_in_bytes()); 1917 } 1918 1919 heap->resize_all_tlabs(); 1920 1921 // Resize the metaspace capacity after a collection 1922 MetaspaceGC::compute_new_size(); 1923 1924 if (log_is_enabled(Debug, gc, heap, exit)) { 1925 accumulated_time()->stop(); 1926 } 1927 1928 young_gen->print_used_change(pre_gc_values.young_gen_used()); 1929 old_gen->print_used_change(pre_gc_values.old_gen_used()); 1930 MetaspaceUtils::print_metaspace_change(pre_gc_values.metadata_used()); 1931 1932 // Track memory usage and detect low memory 1933 MemoryService::track_memory_usage(); 1934 heap->update_counters(); 1935 gc_task_manager()->release_idle_workers(); 1936 1937 heap->post_full_gc_dump(&_gc_timer); 1938 } 1939 1940 #ifdef ASSERT 1941 for (size_t i = 0; i < ParallelGCThreads + 1; ++i) { 1942 ParCompactionManager* const cm = 1943 ParCompactionManager::manager_array(int(i)); 1944 assert(cm->marking_stack()->is_empty(), "should be empty"); 1945 assert(cm->region_stack()->is_empty(), "Region stack " SIZE_FORMAT " is not empty", i); 1946 } 1947 #endif // ASSERT 1948 1949 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 1950 HandleMark hm; // Discard invalid handles created during verification 1951 Universe::verify("After GC"); 1952 } 1953 1954 // Re-verify object start arrays 1955 if (VerifyObjectStartArray && 1956 VerifyAfterGC) { 1957 old_gen->verify_object_start_array(); 1958 } 1959 1960 if (ZapUnusedHeapArea) { 1961 old_gen->object_space()->check_mangled_unused_area_complete(); 1962 } 1963 1964 NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); 1965 1966 collection_exit.update(); 1967 1968 heap->print_heap_after_gc(); 1969 heap->trace_heap_after_gc(&_gc_tracer); 1970 1971 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT, 1972 marking_start.ticks(), compaction_start.ticks(), 1973 collection_exit.ticks()); 1974 gc_task_manager()->print_task_time_stamps(); 1975 1976 #ifdef TRACESPINNING 1977 ParallelTaskTerminator::print_termination_counts(); 1978 #endif 1979 1980 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections()); 1981 1982 _gc_timer.register_gc_end(); 1983 1984 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id)); 1985 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions()); 1986 1987 return true; 1988 } 1989 1990 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, 1991 PSYoungGen* young_gen, 1992 PSOldGen* old_gen) { 1993 MutableSpace* const eden_space = young_gen->eden_space(); 1994 assert(!eden_space->is_empty(), "eden must be non-empty"); 1995 assert(young_gen->virtual_space()->alignment() == 1996 old_gen->virtual_space()->alignment(), "alignments do not match"); 1997 1998 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) { 1999 return false; 2000 } 2001 2002 // Both generations must be completely committed. 2003 if (young_gen->virtual_space()->uncommitted_size() != 0) { 2004 return false; 2005 } 2006 if (old_gen->virtual_space()->uncommitted_size() != 0) { 2007 return false; 2008 } 2009 2010 // Figure out how much to take from eden. Include the average amount promoted 2011 // in the total; otherwise the next young gen GC will simply bail out to a 2012 // full GC. 2013 const size_t alignment = old_gen->virtual_space()->alignment(); 2014 const size_t eden_used = eden_space->used_in_bytes(); 2015 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average(); 2016 const size_t absorb_size = align_up(eden_used + promoted, alignment); 2017 const size_t eden_capacity = eden_space->capacity_in_bytes(); 2018 2019 if (absorb_size >= eden_capacity) { 2020 return false; // Must leave some space in eden. 2021 } 2022 2023 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size; 2024 if (new_young_size < young_gen->min_gen_size()) { 2025 return false; // Respect young gen minimum size. 2026 } 2027 2028 log_trace(gc, ergo, heap)(" absorbing " SIZE_FORMAT "K: " 2029 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K " 2030 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K " 2031 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ", 2032 absorb_size / K, 2033 eden_capacity / K, (eden_capacity - absorb_size) / K, 2034 young_gen->from_space()->used_in_bytes() / K, 2035 young_gen->to_space()->used_in_bytes() / K, 2036 young_gen->capacity_in_bytes() / K, new_young_size / K); 2037 2038 // Fill the unused part of the old gen. 2039 MutableSpace* const old_space = old_gen->object_space(); 2040 HeapWord* const unused_start = old_space->top(); 2041 size_t const unused_words = pointer_delta(old_space->end(), unused_start); 2042 2043 if (unused_words > 0) { 2044 if (unused_words < CollectedHeap::min_fill_size()) { 2045 return false; // If the old gen cannot be filled, must give up. 2046 } 2047 CollectedHeap::fill_with_objects(unused_start, unused_words); 2048 } 2049 2050 // Take the live data from eden and set both top and end in the old gen to 2051 // eden top. (Need to set end because reset_after_change() mangles the region 2052 // from end to virtual_space->high() in debug builds). 2053 HeapWord* const new_top = eden_space->top(); 2054 old_gen->virtual_space()->expand_into(young_gen->virtual_space(), 2055 absorb_size); 2056 young_gen->reset_after_change(); 2057 old_space->set_top(new_top); 2058 old_space->set_end(new_top); 2059 old_gen->reset_after_change(); 2060 2061 // Update the object start array for the filler object and the data from eden. 2062 ObjectStartArray* const start_array = old_gen->start_array(); 2063 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) { 2064 start_array->allocate_block(p); 2065 } 2066 2067 // Could update the promoted average here, but it is not typically updated at 2068 // full GCs and the value to use is unclear. Something like 2069 // 2070 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc. 2071 2072 size_policy->set_bytes_absorbed_from_eden(absorb_size); 2073 return true; 2074 } 2075 2076 GCTaskManager* const PSParallelCompact::gc_task_manager() { 2077 assert(ParallelScavengeHeap::gc_task_manager() != NULL, 2078 "shouldn't return NULL"); 2079 return ParallelScavengeHeap::gc_task_manager(); 2080 } 2081 2082 class PCAddThreadRootsMarkingTaskClosure : public ThreadClosure { 2083 private: 2084 GCTaskQueue* _q; 2085 2086 public: 2087 PCAddThreadRootsMarkingTaskClosure(GCTaskQueue* q) : _q(q) { } 2088 void do_thread(Thread* t) { 2089 _q->enqueue(new ThreadRootsMarkingTask(t)); 2090 } 2091 }; 2092 2093 void PSParallelCompact::marking_phase(ParCompactionManager* cm, 2094 bool maximum_heap_compaction, 2095 ParallelOldTracer *gc_tracer) { 2096 // Recursively traverse all live objects and mark them 2097 GCTraceTime(Info, gc, phases) tm("Marking Phase", &_gc_timer); 2098 2099 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 2100 uint parallel_gc_threads = heap->gc_task_manager()->workers(); 2101 uint active_gc_threads = heap->gc_task_manager()->active_workers(); 2102 TaskQueueSetSuper* qset = ParCompactionManager::stack_array(); 2103 ParallelTaskTerminator terminator(active_gc_threads, qset); 2104 2105 PCMarkAndPushClosure mark_and_push_closure(cm); 2106 ParCompactionManager::FollowStackClosure follow_stack_closure(cm); 2107 2108 // Need new claim bits before marking starts. 2109 ClassLoaderDataGraph::clear_claimed_marks(); 2110 2111 { 2112 GCTraceTime(Debug, gc, phases) tm("Par Mark", &_gc_timer); 2113 2114 ParallelScavengeHeap::ParStrongRootsScope psrs; 2115 2116 GCTaskQueue* q = GCTaskQueue::create(); 2117 2118 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe)); 2119 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles)); 2120 // We scan the thread roots in parallel 2121 PCAddThreadRootsMarkingTaskClosure cl(q); 2122 Threads::java_threads_and_vm_thread_do(&cl); 2123 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer)); 2124 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management)); 2125 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary)); 2126 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::class_loader_data)); 2127 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti)); 2128 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache)); 2129 2130 if (active_gc_threads > 1) { 2131 for (uint j = 0; j < active_gc_threads; j++) { 2132 q->enqueue(new StealMarkingTask(&terminator)); 2133 } 2134 } 2135 2136 gc_task_manager()->execute_and_wait(q); 2137 } 2138 2139 // Process reference objects found during marking 2140 { 2141 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer); 2142 2143 ReferenceProcessorStats stats; 2144 ReferenceProcessorPhaseTimes pt(&_gc_timer, ref_processor()->max_num_queues()); 2145 2146 if (ref_processor()->processing_is_mt()) { 2147 ref_processor()->set_active_mt_degree(active_gc_threads); 2148 2149 RefProcTaskExecutor task_executor; 2150 stats = ref_processor()->process_discovered_references( 2151 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, 2152 &task_executor, &pt); 2153 } else { 2154 stats = ref_processor()->process_discovered_references( 2155 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL, 2156 &pt); 2157 } 2158 2159 gc_tracer->report_gc_reference_stats(stats); 2160 pt.print_all_references(); 2161 } 2162 2163 // This is the point where the entire marking should have completed. 2164 assert(cm->marking_stacks_empty(), "Marking should have completed"); 2165 2166 { 2167 GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer); 2168 WeakProcessor::weak_oops_do(is_alive_closure(), &do_nothing_cl); 2169 } 2170 2171 { 2172 GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", &_gc_timer); 2173 2174 // Follow system dictionary roots and unload classes. 2175 bool purged_class = SystemDictionary::do_unloading(&_gc_timer); 2176 2177 // Unload nmethods. 2178 CodeCache::do_unloading(is_alive_closure(), purged_class); 2179 2180 // Prune dead klasses from subklass/sibling/implementor lists. 2181 Klass::clean_weak_klass_links(purged_class); 2182 } 2183 2184 { 2185 GCTraceTime(Debug, gc, phases) t("Scrub String Table", &_gc_timer); 2186 // Delete entries for dead interned strings. 2187 StringTable::unlink(is_alive_closure()); 2188 } 2189 2190 { 2191 GCTraceTime(Debug, gc, phases) t("Scrub Symbol Table", &_gc_timer); 2192 // Clean up unreferenced symbols in symbol table. 2193 SymbolTable::unlink(); 2194 } 2195 2196 _gc_tracer.report_object_count_after_gc(is_alive_closure()); 2197 } 2198 2199 void PSParallelCompact::adjust_roots(ParCompactionManager* cm) { 2200 // Adjust the pointers to reflect the new locations 2201 GCTraceTime(Info, gc, phases) tm("Adjust Roots", &_gc_timer); 2202 2203 // Need new claim bits when tracing through and adjusting pointers. 2204 ClassLoaderDataGraph::clear_claimed_marks(); 2205 2206 PCAdjustPointerClosure oop_closure(cm); 2207 2208 // General strong roots. 2209 Universe::oops_do(&oop_closure); 2210 JNIHandles::oops_do(&oop_closure); // Global (strong) JNI handles 2211 Threads::oops_do(&oop_closure, NULL); 2212 ObjectSynchronizer::oops_do(&oop_closure); 2213 Management::oops_do(&oop_closure); 2214 JvmtiExport::oops_do(&oop_closure); 2215 SystemDictionary::oops_do(&oop_closure); 2216 CLDToOopClosure cld_closure(&oop_closure, ClassLoaderData::_claim_strong); 2217 ClassLoaderDataGraph::cld_oops_do(&cld_closure); 2218 2219 // Now adjust pointers in remaining weak roots. (All of which should 2220 // have been cleared if they pointed to non-surviving objects.) 2221 WeakProcessor::oops_do(&oop_closure); 2222 2223 CodeBlobToOopClosure adjust_from_blobs(&oop_closure, CodeBlobToOopClosure::FixRelocations); 2224 CodeCache::blobs_do(&adjust_from_blobs); 2225 AOTLoader::oops_do(&oop_closure); 2226 StringTable::oops_do(&oop_closure); 2227 ref_processor()->weak_oops_do(&oop_closure); 2228 // Roots were visited so references into the young gen in roots 2229 // may have been scanned. Process them also. 2230 // Should the reference processor have a span that excludes 2231 // young gen objects? 2232 PSScavenge::reference_processor()->weak_oops_do(&oop_closure); 2233 } 2234 2235 // Helper class to print 8 region numbers per line and then print the total at the end. 2236 class FillableRegionLogger : public StackObj { 2237 private: 2238 Log(gc, compaction) log; 2239 static const int LineLength = 8; 2240 size_t _regions[LineLength]; 2241 int _next_index; 2242 bool _enabled; 2243 size_t _total_regions; 2244 public: 2245 FillableRegionLogger() : _next_index(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)), _total_regions(0) { } 2246 ~FillableRegionLogger() { 2247 log.trace(SIZE_FORMAT " initially fillable regions", _total_regions); 2248 } 2249 2250 void print_line() { 2251 if (!_enabled || _next_index == 0) { 2252 return; 2253 } 2254 FormatBuffer<> line("Fillable: "); 2255 for (int i = 0; i < _next_index; i++) { 2256 line.append(" " SIZE_FORMAT_W(7), _regions[i]); 2257 } 2258 log.trace("%s", line.buffer()); 2259 _next_index = 0; 2260 } 2261 2262 void handle(size_t region) { 2263 if (!_enabled) { 2264 return; 2265 } 2266 _regions[_next_index++] = region; 2267 if (_next_index == LineLength) { 2268 print_line(); 2269 } 2270 _total_regions++; 2271 } 2272 }; 2273 2274 void PSParallelCompact::prepare_region_draining_tasks(GCTaskQueue* q, 2275 uint parallel_gc_threads) 2276 { 2277 GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer); 2278 2279 // Find the threads that are active 2280 unsigned int which = 0; 2281 2282 // Find all regions that are available (can be filled immediately) and 2283 // distribute them to the thread stacks. The iteration is done in reverse 2284 // order (high to low) so the regions will be removed in ascending order. 2285 2286 const ParallelCompactData& sd = PSParallelCompact::summary_data(); 2287 2288 which = 0; 2289 // id + 1 is used to test termination so unsigned can 2290 // be used with an old_space_id == 0. 2291 FillableRegionLogger region_logger; 2292 for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) { 2293 SpaceInfo* const space_info = _space_info + id; 2294 MutableSpace* const space = space_info->space(); 2295 HeapWord* const new_top = space_info->new_top(); 2296 2297 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix()); 2298 const size_t end_region = 2299 sd.addr_to_region_idx(sd.region_align_up(new_top)); 2300 2301 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) { 2302 if (sd.region(cur)->claim_unsafe()) { 2303 ParCompactionManager* cm = ParCompactionManager::manager_array(which); 2304 cm->region_stack()->push(cur); 2305 region_logger.handle(cur); 2306 // Assign regions to tasks in round-robin fashion. 2307 if (++which == parallel_gc_threads) { 2308 which = 0; 2309 } 2310 } 2311 } 2312 region_logger.print_line(); 2313 } 2314 } 2315 2316 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4 2317 2318 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q, 2319 uint parallel_gc_threads) { 2320 GCTraceTime(Trace, gc, phases) tm("Dense Prefix Task Setup", &_gc_timer); 2321 2322 ParallelCompactData& sd = PSParallelCompact::summary_data(); 2323 2324 // Iterate over all the spaces adding tasks for updating 2325 // regions in the dense prefix. Assume that 1 gc thread 2326 // will work on opening the gaps and the remaining gc threads 2327 // will work on the dense prefix. 2328 unsigned int space_id; 2329 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) { 2330 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix(); 2331 const MutableSpace* const space = _space_info[space_id].space(); 2332 2333 if (dense_prefix_end == space->bottom()) { 2334 // There is no dense prefix for this space. 2335 continue; 2336 } 2337 2338 // The dense prefix is before this region. 2339 size_t region_index_end_dense_prefix = 2340 sd.addr_to_region_idx(dense_prefix_end); 2341 RegionData* const dense_prefix_cp = 2342 sd.region(region_index_end_dense_prefix); 2343 assert(dense_prefix_end == space->end() || 2344 dense_prefix_cp->available() || 2345 dense_prefix_cp->claimed(), 2346 "The region after the dense prefix should always be ready to fill"); 2347 2348 size_t region_index_start = sd.addr_to_region_idx(space->bottom()); 2349 2350 // Is there dense prefix work? 2351 size_t total_dense_prefix_regions = 2352 region_index_end_dense_prefix - region_index_start; 2353 // How many regions of the dense prefix should be given to 2354 // each thread? 2355 if (total_dense_prefix_regions > 0) { 2356 uint tasks_for_dense_prefix = 1; 2357 if (total_dense_prefix_regions <= 2358 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) { 2359 // Don't over partition. This assumes that 2360 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value 2361 // so there are not many regions to process. 2362 tasks_for_dense_prefix = parallel_gc_threads; 2363 } else { 2364 // Over partition 2365 tasks_for_dense_prefix = parallel_gc_threads * 2366 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING; 2367 } 2368 size_t regions_per_thread = total_dense_prefix_regions / 2369 tasks_for_dense_prefix; 2370 // Give each thread at least 1 region. 2371 if (regions_per_thread == 0) { 2372 regions_per_thread = 1; 2373 } 2374 2375 for (uint k = 0; k < tasks_for_dense_prefix; k++) { 2376 if (region_index_start >= region_index_end_dense_prefix) { 2377 break; 2378 } 2379 // region_index_end is not processed 2380 size_t region_index_end = MIN2(region_index_start + regions_per_thread, 2381 region_index_end_dense_prefix); 2382 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id), 2383 region_index_start, 2384 region_index_end)); 2385 region_index_start = region_index_end; 2386 } 2387 } 2388 // This gets any part of the dense prefix that did not 2389 // fit evenly. 2390 if (region_index_start < region_index_end_dense_prefix) { 2391 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id), 2392 region_index_start, 2393 region_index_end_dense_prefix)); 2394 } 2395 } 2396 } 2397 2398 void PSParallelCompact::enqueue_region_stealing_tasks( 2399 GCTaskQueue* q, 2400 ParallelTaskTerminator* terminator_ptr, 2401 uint parallel_gc_threads) { 2402 GCTraceTime(Trace, gc, phases) tm("Steal Task Setup", &_gc_timer); 2403 2404 // Once a thread has drained it's stack, it should try to steal regions from 2405 // other threads. 2406 for (uint j = 0; j < parallel_gc_threads; j++) { 2407 q->enqueue(new CompactionWithStealingTask(terminator_ptr)); 2408 } 2409 } 2410 2411 #ifdef ASSERT 2412 // Write a histogram of the number of times the block table was filled for a 2413 // region. 2414 void PSParallelCompact::write_block_fill_histogram() 2415 { 2416 if (!log_develop_is_enabled(Trace, gc, compaction)) { 2417 return; 2418 } 2419 2420 Log(gc, compaction) log; 2421 ResourceMark rm; 2422 LogStream ls(log.trace()); 2423 outputStream* out = &ls; 2424 2425 typedef ParallelCompactData::RegionData rd_t; 2426 ParallelCompactData& sd = summary_data(); 2427 2428 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2429 MutableSpace* const spc = _space_info[id].space(); 2430 if (spc->bottom() != spc->top()) { 2431 const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom()); 2432 HeapWord* const top_aligned_up = sd.region_align_up(spc->top()); 2433 const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up); 2434 2435 size_t histo[5] = { 0, 0, 0, 0, 0 }; 2436 const size_t histo_len = sizeof(histo) / sizeof(size_t); 2437 const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t)); 2438 2439 for (const rd_t* cur = beg; cur < end; ++cur) { 2440 ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)]; 2441 } 2442 out->print("Block fill histogram: %u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt); 2443 for (size_t i = 0; i < histo_len; ++i) { 2444 out->print(" " SIZE_FORMAT_W(5) " %5.1f%%", 2445 histo[i], 100.0 * histo[i] / region_cnt); 2446 } 2447 out->cr(); 2448 } 2449 } 2450 } 2451 #endif // #ifdef ASSERT 2452 2453 void PSParallelCompact::compact() { 2454 GCTraceTime(Info, gc, phases) tm("Compaction Phase", &_gc_timer); 2455 2456 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 2457 PSOldGen* old_gen = heap->old_gen(); 2458 old_gen->start_array()->reset(); 2459 uint parallel_gc_threads = heap->gc_task_manager()->workers(); 2460 uint active_gc_threads = heap->gc_task_manager()->active_workers(); 2461 TaskQueueSetSuper* qset = ParCompactionManager::region_array(); 2462 ParallelTaskTerminator terminator(active_gc_threads, qset); 2463 2464 GCTaskQueue* q = GCTaskQueue::create(); 2465 prepare_region_draining_tasks(q, active_gc_threads); 2466 enqueue_dense_prefix_tasks(q, active_gc_threads); 2467 enqueue_region_stealing_tasks(q, &terminator, active_gc_threads); 2468 2469 { 2470 GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer); 2471 2472 gc_task_manager()->execute_and_wait(q); 2473 2474 #ifdef ASSERT 2475 // Verify that all regions have been processed before the deferred updates. 2476 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2477 verify_complete(SpaceId(id)); 2478 } 2479 #endif 2480 } 2481 2482 { 2483 // Update the deferred objects, if any. Any compaction manager can be used. 2484 GCTraceTime(Trace, gc, phases) tm("Deferred Updates", &_gc_timer); 2485 ParCompactionManager* cm = ParCompactionManager::manager_array(0); 2486 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2487 update_deferred_objects(cm, SpaceId(id)); 2488 } 2489 } 2490 2491 DEBUG_ONLY(write_block_fill_histogram()); 2492 } 2493 2494 #ifdef ASSERT 2495 void PSParallelCompact::verify_complete(SpaceId space_id) { 2496 // All Regions between space bottom() to new_top() should be marked as filled 2497 // and all Regions between new_top() and top() should be available (i.e., 2498 // should have been emptied). 2499 ParallelCompactData& sd = summary_data(); 2500 SpaceInfo si = _space_info[space_id]; 2501 HeapWord* new_top_addr = sd.region_align_up(si.new_top()); 2502 HeapWord* old_top_addr = sd.region_align_up(si.space()->top()); 2503 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom()); 2504 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr); 2505 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr); 2506 2507 bool issued_a_warning = false; 2508 2509 size_t cur_region; 2510 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) { 2511 const RegionData* const c = sd.region(cur_region); 2512 if (!c->completed()) { 2513 log_warning(gc)("region " SIZE_FORMAT " not filled: destination_count=%u", 2514 cur_region, c->destination_count()); 2515 issued_a_warning = true; 2516 } 2517 } 2518 2519 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) { 2520 const RegionData* const c = sd.region(cur_region); 2521 if (!c->available()) { 2522 log_warning(gc)("region " SIZE_FORMAT " not empty: destination_count=%u", 2523 cur_region, c->destination_count()); 2524 issued_a_warning = true; 2525 } 2526 } 2527 2528 if (issued_a_warning) { 2529 print_region_ranges(); 2530 } 2531 } 2532 #endif // #ifdef ASSERT 2533 2534 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) { 2535 _start_array->allocate_block(addr); 2536 compaction_manager()->update_contents(oop(addr)); 2537 } 2538 2539 // Update interior oops in the ranges of regions [beg_region, end_region). 2540 void 2541 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm, 2542 SpaceId space_id, 2543 size_t beg_region, 2544 size_t end_region) { 2545 ParallelCompactData& sd = summary_data(); 2546 ParMarkBitMap* const mbm = mark_bitmap(); 2547 2548 HeapWord* beg_addr = sd.region_to_addr(beg_region); 2549 HeapWord* const end_addr = sd.region_to_addr(end_region); 2550 assert(beg_region <= end_region, "bad region range"); 2551 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix"); 2552 2553 #ifdef ASSERT 2554 // Claim the regions to avoid triggering an assert when they are marked as 2555 // filled. 2556 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) { 2557 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed"); 2558 } 2559 #endif // #ifdef ASSERT 2560 2561 if (beg_addr != space(space_id)->bottom()) { 2562 // Find the first live object or block of dead space that *starts* in this 2563 // range of regions. If a partial object crosses onto the region, skip it; 2564 // it will be marked for 'deferred update' when the object head is 2565 // processed. If dead space crosses onto the region, it is also skipped; it 2566 // will be filled when the prior region is processed. If neither of those 2567 // apply, the first word in the region is the start of a live object or dead 2568 // space. 2569 assert(beg_addr > space(space_id)->bottom(), "sanity"); 2570 const RegionData* const cp = sd.region(beg_region); 2571 if (cp->partial_obj_size() != 0) { 2572 beg_addr = sd.partial_obj_end(beg_region); 2573 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) { 2574 beg_addr = mbm->find_obj_beg(beg_addr, end_addr); 2575 } 2576 } 2577 2578 if (beg_addr < end_addr) { 2579 // A live object or block of dead space starts in this range of Regions. 2580 HeapWord* const dense_prefix_end = dense_prefix(space_id); 2581 2582 // Create closures and iterate. 2583 UpdateOnlyClosure update_closure(mbm, cm, space_id); 2584 FillClosure fill_closure(cm, space_id); 2585 ParMarkBitMap::IterationStatus status; 2586 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr, 2587 dense_prefix_end); 2588 if (status == ParMarkBitMap::incomplete) { 2589 update_closure.do_addr(update_closure.source()); 2590 } 2591 } 2592 2593 // Mark the regions as filled. 2594 RegionData* const beg_cp = sd.region(beg_region); 2595 RegionData* const end_cp = sd.region(end_region); 2596 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) { 2597 cp->set_completed(); 2598 } 2599 } 2600 2601 // Return the SpaceId for the space containing addr. If addr is not in the 2602 // heap, last_space_id is returned. In debug mode it expects the address to be 2603 // in the heap and asserts such. 2604 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) { 2605 assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap"); 2606 2607 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2608 if (_space_info[id].space()->contains(addr)) { 2609 return SpaceId(id); 2610 } 2611 } 2612 2613 assert(false, "no space contains the addr"); 2614 return last_space_id; 2615 } 2616 2617 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm, 2618 SpaceId id) { 2619 assert(id < last_space_id, "bad space id"); 2620 2621 ParallelCompactData& sd = summary_data(); 2622 const SpaceInfo* const space_info = _space_info + id; 2623 ObjectStartArray* const start_array = space_info->start_array(); 2624 2625 const MutableSpace* const space = space_info->space(); 2626 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set"); 2627 HeapWord* const beg_addr = space_info->dense_prefix(); 2628 HeapWord* const end_addr = sd.region_align_up(space_info->new_top()); 2629 2630 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr); 2631 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr); 2632 const RegionData* cur_region; 2633 for (cur_region = beg_region; cur_region < end_region; ++cur_region) { 2634 HeapWord* const addr = cur_region->deferred_obj_addr(); 2635 if (addr != NULL) { 2636 if (start_array != NULL) { 2637 start_array->allocate_block(addr); 2638 } 2639 cm->update_contents(oop(addr)); 2640 assert(oopDesc::is_oop_or_null(oop(addr)), "Expected an oop or NULL at " PTR_FORMAT, p2i(oop(addr))); 2641 } 2642 } 2643 } 2644 2645 // Skip over count live words starting from beg, and return the address of the 2646 // next live word. Unless marked, the word corresponding to beg is assumed to 2647 // be dead. Callers must either ensure beg does not correspond to the middle of 2648 // an object, or account for those live words in some other way. Callers must 2649 // also ensure that there are enough live words in the range [beg, end) to skip. 2650 HeapWord* 2651 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count) 2652 { 2653 assert(count > 0, "sanity"); 2654 2655 ParMarkBitMap* m = mark_bitmap(); 2656 idx_t bits_to_skip = m->words_to_bits(count); 2657 idx_t cur_beg = m->addr_to_bit(beg); 2658 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end)); 2659 2660 do { 2661 cur_beg = m->find_obj_beg(cur_beg, search_end); 2662 idx_t cur_end = m->find_obj_end(cur_beg, search_end); 2663 const size_t obj_bits = cur_end - cur_beg + 1; 2664 if (obj_bits > bits_to_skip) { 2665 return m->bit_to_addr(cur_beg + bits_to_skip); 2666 } 2667 bits_to_skip -= obj_bits; 2668 cur_beg = cur_end + 1; 2669 } while (bits_to_skip > 0); 2670 2671 // Skipping the desired number of words landed just past the end of an object. 2672 // Find the start of the next object. 2673 cur_beg = m->find_obj_beg(cur_beg, search_end); 2674 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip"); 2675 return m->bit_to_addr(cur_beg); 2676 } 2677 2678 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr, 2679 SpaceId src_space_id, 2680 size_t src_region_idx) 2681 { 2682 assert(summary_data().is_region_aligned(dest_addr), "not aligned"); 2683 2684 const SplitInfo& split_info = _space_info[src_space_id].split_info(); 2685 if (split_info.dest_region_addr() == dest_addr) { 2686 // The partial object ending at the split point contains the first word to 2687 // be copied to dest_addr. 2688 return split_info.first_src_addr(); 2689 } 2690 2691 const ParallelCompactData& sd = summary_data(); 2692 ParMarkBitMap* const bitmap = mark_bitmap(); 2693 const size_t RegionSize = ParallelCompactData::RegionSize; 2694 2695 assert(sd.is_region_aligned(dest_addr), "not aligned"); 2696 const RegionData* const src_region_ptr = sd.region(src_region_idx); 2697 const size_t partial_obj_size = src_region_ptr->partial_obj_size(); 2698 HeapWord* const src_region_destination = src_region_ptr->destination(); 2699 2700 assert(dest_addr >= src_region_destination, "wrong src region"); 2701 assert(src_region_ptr->data_size() > 0, "src region cannot be empty"); 2702 2703 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx); 2704 HeapWord* const src_region_end = src_region_beg + RegionSize; 2705 2706 HeapWord* addr = src_region_beg; 2707 if (dest_addr == src_region_destination) { 2708 // Return the first live word in the source region. 2709 if (partial_obj_size == 0) { 2710 addr = bitmap->find_obj_beg(addr, src_region_end); 2711 assert(addr < src_region_end, "no objects start in src region"); 2712 } 2713 return addr; 2714 } 2715 2716 // Must skip some live data. 2717 size_t words_to_skip = dest_addr - src_region_destination; 2718 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region"); 2719 2720 if (partial_obj_size >= words_to_skip) { 2721 // All the live words to skip are part of the partial object. 2722 addr += words_to_skip; 2723 if (partial_obj_size == words_to_skip) { 2724 // Find the first live word past the partial object. 2725 addr = bitmap->find_obj_beg(addr, src_region_end); 2726 assert(addr < src_region_end, "wrong src region"); 2727 } 2728 return addr; 2729 } 2730 2731 // Skip over the partial object (if any). 2732 if (partial_obj_size != 0) { 2733 words_to_skip -= partial_obj_size; 2734 addr += partial_obj_size; 2735 } 2736 2737 // Skip over live words due to objects that start in the region. 2738 addr = skip_live_words(addr, src_region_end, words_to_skip); 2739 assert(addr < src_region_end, "wrong src region"); 2740 return addr; 2741 } 2742 2743 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm, 2744 SpaceId src_space_id, 2745 size_t beg_region, 2746 HeapWord* end_addr) 2747 { 2748 ParallelCompactData& sd = summary_data(); 2749 2750 #ifdef ASSERT 2751 MutableSpace* const src_space = _space_info[src_space_id].space(); 2752 HeapWord* const beg_addr = sd.region_to_addr(beg_region); 2753 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(), 2754 "src_space_id does not match beg_addr"); 2755 assert(src_space->contains(end_addr) || end_addr == src_space->end(), 2756 "src_space_id does not match end_addr"); 2757 #endif // #ifdef ASSERT 2758 2759 RegionData* const beg = sd.region(beg_region); 2760 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr)); 2761 2762 // Regions up to new_top() are enqueued if they become available. 2763 HeapWord* const new_top = _space_info[src_space_id].new_top(); 2764 RegionData* const enqueue_end = 2765 sd.addr_to_region_ptr(sd.region_align_up(new_top)); 2766 2767 for (RegionData* cur = beg; cur < end; ++cur) { 2768 assert(cur->data_size() > 0, "region must have live data"); 2769 cur->decrement_destination_count(); 2770 if (cur < enqueue_end && cur->available() && cur->claim()) { 2771 cm->push_region(sd.region(cur)); 2772 } 2773 } 2774 } 2775 2776 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure, 2777 SpaceId& src_space_id, 2778 HeapWord*& src_space_top, 2779 HeapWord* end_addr) 2780 { 2781 typedef ParallelCompactData::RegionData RegionData; 2782 2783 ParallelCompactData& sd = PSParallelCompact::summary_data(); 2784 const size_t region_size = ParallelCompactData::RegionSize; 2785 2786 size_t src_region_idx = 0; 2787 2788 // Skip empty regions (if any) up to the top of the space. 2789 HeapWord* const src_aligned_up = sd.region_align_up(end_addr); 2790 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up); 2791 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top); 2792 const RegionData* const top_region_ptr = 2793 sd.addr_to_region_ptr(top_aligned_up); 2794 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) { 2795 ++src_region_ptr; 2796 } 2797 2798 if (src_region_ptr < top_region_ptr) { 2799 // The next source region is in the current space. Update src_region_idx 2800 // and the source address to match src_region_ptr. 2801 src_region_idx = sd.region(src_region_ptr); 2802 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx); 2803 if (src_region_addr > closure.source()) { 2804 closure.set_source(src_region_addr); 2805 } 2806 return src_region_idx; 2807 } 2808 2809 // Switch to a new source space and find the first non-empty region. 2810 unsigned int space_id = src_space_id + 1; 2811 assert(space_id < last_space_id, "not enough spaces"); 2812 2813 HeapWord* const destination = closure.destination(); 2814 2815 do { 2816 MutableSpace* space = _space_info[space_id].space(); 2817 HeapWord* const bottom = space->bottom(); 2818 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom); 2819 2820 // Iterate over the spaces that do not compact into themselves. 2821 if (bottom_cp->destination() != bottom) { 2822 HeapWord* const top_aligned_up = sd.region_align_up(space->top()); 2823 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up); 2824 2825 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) { 2826 if (src_cp->live_obj_size() > 0) { 2827 // Found it. 2828 assert(src_cp->destination() == destination, 2829 "first live obj in the space must match the destination"); 2830 assert(src_cp->partial_obj_size() == 0, 2831 "a space cannot begin with a partial obj"); 2832 2833 src_space_id = SpaceId(space_id); 2834 src_space_top = space->top(); 2835 const size_t src_region_idx = sd.region(src_cp); 2836 closure.set_source(sd.region_to_addr(src_region_idx)); 2837 return src_region_idx; 2838 } else { 2839 assert(src_cp->data_size() == 0, "sanity"); 2840 } 2841 } 2842 } 2843 } while (++space_id < last_space_id); 2844 2845 assert(false, "no source region was found"); 2846 return 0; 2847 } 2848 2849 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx) 2850 { 2851 typedef ParMarkBitMap::IterationStatus IterationStatus; 2852 const size_t RegionSize = ParallelCompactData::RegionSize; 2853 ParMarkBitMap* const bitmap = mark_bitmap(); 2854 ParallelCompactData& sd = summary_data(); 2855 RegionData* const region_ptr = sd.region(region_idx); 2856 2857 // Get the items needed to construct the closure. 2858 HeapWord* dest_addr = sd.region_to_addr(region_idx); 2859 SpaceId dest_space_id = space_id(dest_addr); 2860 ObjectStartArray* start_array = _space_info[dest_space_id].start_array(); 2861 HeapWord* new_top = _space_info[dest_space_id].new_top(); 2862 assert(dest_addr < new_top, "sanity"); 2863 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize); 2864 2865 // Get the source region and related info. 2866 size_t src_region_idx = region_ptr->source_region(); 2867 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx)); 2868 HeapWord* src_space_top = _space_info[src_space_id].space()->top(); 2869 2870 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words); 2871 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx)); 2872 2873 // Adjust src_region_idx to prepare for decrementing destination counts (the 2874 // destination count is not decremented when a region is copied to itself). 2875 if (src_region_idx == region_idx) { 2876 src_region_idx += 1; 2877 } 2878 2879 if (bitmap->is_unmarked(closure.source())) { 2880 // The first source word is in the middle of an object; copy the remainder 2881 // of the object or as much as will fit. The fact that pointer updates were 2882 // deferred will be noted when the object header is processed. 2883 HeapWord* const old_src_addr = closure.source(); 2884 closure.copy_partial_obj(); 2885 if (closure.is_full()) { 2886 decrement_destination_counts(cm, src_space_id, src_region_idx, 2887 closure.source()); 2888 region_ptr->set_deferred_obj_addr(NULL); 2889 region_ptr->set_completed(); 2890 return; 2891 } 2892 2893 HeapWord* const end_addr = sd.region_align_down(closure.source()); 2894 if (sd.region_align_down(old_src_addr) != end_addr) { 2895 // The partial object was copied from more than one source region. 2896 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr); 2897 2898 // Move to the next source region, possibly switching spaces as well. All 2899 // args except end_addr may be modified. 2900 src_region_idx = next_src_region(closure, src_space_id, src_space_top, 2901 end_addr); 2902 } 2903 } 2904 2905 do { 2906 HeapWord* const cur_addr = closure.source(); 2907 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1), 2908 src_space_top); 2909 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr); 2910 2911 if (status == ParMarkBitMap::incomplete) { 2912 // The last obj that starts in the source region does not end in the 2913 // region. 2914 assert(closure.source() < end_addr, "sanity"); 2915 HeapWord* const obj_beg = closure.source(); 2916 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(), 2917 src_space_top); 2918 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end); 2919 if (obj_end < range_end) { 2920 // The end was found; the entire object will fit. 2921 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end)); 2922 assert(status != ParMarkBitMap::would_overflow, "sanity"); 2923 } else { 2924 // The end was not found; the object will not fit. 2925 assert(range_end < src_space_top, "obj cannot cross space boundary"); 2926 status = ParMarkBitMap::would_overflow; 2927 } 2928 } 2929 2930 if (status == ParMarkBitMap::would_overflow) { 2931 // The last object did not fit. Note that interior oop updates were 2932 // deferred, then copy enough of the object to fill the region. 2933 region_ptr->set_deferred_obj_addr(closure.destination()); 2934 status = closure.copy_until_full(); // copies from closure.source() 2935 2936 decrement_destination_counts(cm, src_space_id, src_region_idx, 2937 closure.source()); 2938 region_ptr->set_completed(); 2939 return; 2940 } 2941 2942 if (status == ParMarkBitMap::full) { 2943 decrement_destination_counts(cm, src_space_id, src_region_idx, 2944 closure.source()); 2945 region_ptr->set_deferred_obj_addr(NULL); 2946 region_ptr->set_completed(); 2947 return; 2948 } 2949 2950 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr); 2951 2952 // Move to the next source region, possibly switching spaces as well. All 2953 // args except end_addr may be modified. 2954 src_region_idx = next_src_region(closure, src_space_id, src_space_top, 2955 end_addr); 2956 } while (true); 2957 } 2958 2959 void PSParallelCompact::fill_blocks(size_t region_idx) 2960 { 2961 // Fill in the block table elements for the specified region. Each block 2962 // table element holds the number of live words in the region that are to the 2963 // left of the first object that starts in the block. Thus only blocks in 2964 // which an object starts need to be filled. 2965 // 2966 // The algorithm scans the section of the bitmap that corresponds to the 2967 // region, keeping a running total of the live words. When an object start is 2968 // found, if it's the first to start in the block that contains it, the 2969 // current total is written to the block table element. 2970 const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize; 2971 const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize; 2972 const size_t RegionSize = ParallelCompactData::RegionSize; 2973 2974 ParallelCompactData& sd = summary_data(); 2975 const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size(); 2976 if (partial_obj_size >= RegionSize) { 2977 return; // No objects start in this region. 2978 } 2979 2980 // Ensure the first loop iteration decides that the block has changed. 2981 size_t cur_block = sd.block_count(); 2982 2983 const ParMarkBitMap* const bitmap = mark_bitmap(); 2984 2985 const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment; 2986 assert((size_t)1 << Log2BitsPerBlock == 2987 bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity"); 2988 2989 size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize); 2990 const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize); 2991 size_t live_bits = bitmap->words_to_bits(partial_obj_size); 2992 beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end); 2993 while (beg_bit < range_end) { 2994 const size_t new_block = beg_bit >> Log2BitsPerBlock; 2995 if (new_block != cur_block) { 2996 cur_block = new_block; 2997 sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits)); 2998 } 2999 3000 const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end); 3001 if (end_bit < range_end - 1) { 3002 live_bits += end_bit - beg_bit + 1; 3003 beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end); 3004 } else { 3005 return; 3006 } 3007 } 3008 } 3009 3010 void 3011 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) { 3012 const MutableSpace* sp = space(space_id); 3013 if (sp->is_empty()) { 3014 return; 3015 } 3016 3017 ParallelCompactData& sd = PSParallelCompact::summary_data(); 3018 ParMarkBitMap* const bitmap = mark_bitmap(); 3019 HeapWord* const dp_addr = dense_prefix(space_id); 3020 HeapWord* beg_addr = sp->bottom(); 3021 HeapWord* end_addr = sp->top(); 3022 3023 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix"); 3024 3025 const size_t beg_region = sd.addr_to_region_idx(beg_addr); 3026 const size_t dp_region = sd.addr_to_region_idx(dp_addr); 3027 if (beg_region < dp_region) { 3028 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region); 3029 } 3030 3031 // The destination of the first live object that starts in the region is one 3032 // past the end of the partial object entering the region (if any). 3033 HeapWord* const dest_addr = sd.partial_obj_end(dp_region); 3034 HeapWord* const new_top = _space_info[space_id].new_top(); 3035 assert(new_top >= dest_addr, "bad new_top value"); 3036 const size_t words = pointer_delta(new_top, dest_addr); 3037 3038 if (words > 0) { 3039 ObjectStartArray* start_array = _space_info[space_id].start_array(); 3040 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words); 3041 3042 ParMarkBitMap::IterationStatus status; 3043 status = bitmap->iterate(&closure, dest_addr, end_addr); 3044 assert(status == ParMarkBitMap::full, "iteration not complete"); 3045 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr, 3046 "live objects skipped because closure is full"); 3047 } 3048 } 3049 3050 jlong PSParallelCompact::millis_since_last_gc() { 3051 // We need a monotonically non-decreasing time in ms but 3052 // os::javaTimeMillis() does not guarantee monotonicity. 3053 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 3054 jlong ret_val = now - _time_of_last_gc; 3055 // XXX See note in genCollectedHeap::millis_since_last_gc(). 3056 if (ret_val < 0) { 3057 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);) 3058 return 0; 3059 } 3060 return ret_val; 3061 } 3062 3063 void PSParallelCompact::reset_millis_since_last_gc() { 3064 // We need a monotonically non-decreasing time in ms but 3065 // os::javaTimeMillis() does not guarantee monotonicity. 3066 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 3067 } 3068 3069 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full() 3070 { 3071 if (source() != destination()) { 3072 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3073 Copy::aligned_conjoint_words(source(), destination(), words_remaining()); 3074 } 3075 update_state(words_remaining()); 3076 assert(is_full(), "sanity"); 3077 return ParMarkBitMap::full; 3078 } 3079 3080 void MoveAndUpdateClosure::copy_partial_obj() 3081 { 3082 size_t words = words_remaining(); 3083 3084 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end()); 3085 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end); 3086 if (end_addr < range_end) { 3087 words = bitmap()->obj_size(source(), end_addr); 3088 } 3089 3090 // This test is necessary; if omitted, the pointer updates to a partial object 3091 // that crosses the dense prefix boundary could be overwritten. 3092 if (source() != destination()) { 3093 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3094 Copy::aligned_conjoint_words(source(), destination(), words); 3095 } 3096 update_state(words); 3097 } 3098 3099 ParMarkBitMapClosure::IterationStatus 3100 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) { 3101 assert(destination() != NULL, "sanity"); 3102 assert(bitmap()->obj_size(addr) == words, "bad size"); 3103 3104 _source = addr; 3105 assert(PSParallelCompact::summary_data().calc_new_pointer(source(), compaction_manager()) == 3106 destination(), "wrong destination"); 3107 3108 if (words > words_remaining()) { 3109 return ParMarkBitMap::would_overflow; 3110 } 3111 3112 // The start_array must be updated even if the object is not moving. 3113 if (_start_array != NULL) { 3114 _start_array->allocate_block(destination()); 3115 } 3116 3117 if (destination() != source()) { 3118 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3119 Copy::aligned_conjoint_words(source(), destination(), words); 3120 } 3121 3122 oop moved_oop = (oop) destination(); 3123 compaction_manager()->update_contents(moved_oop); 3124 assert(oopDesc::is_oop_or_null(moved_oop), "Expected an oop or NULL at " PTR_FORMAT, p2i(moved_oop)); 3125 3126 update_state(words); 3127 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity"); 3128 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete; 3129 } 3130 3131 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm, 3132 ParCompactionManager* cm, 3133 PSParallelCompact::SpaceId space_id) : 3134 ParMarkBitMapClosure(mbm, cm), 3135 _space_id(space_id), 3136 _start_array(PSParallelCompact::start_array(space_id)) 3137 { 3138 } 3139 3140 // Updates the references in the object to their new values. 3141 ParMarkBitMapClosure::IterationStatus 3142 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) { 3143 do_addr(addr); 3144 return ParMarkBitMap::incomplete; 3145 } 3146 3147 FillClosure::FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) : 3148 ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm), 3149 _start_array(PSParallelCompact::start_array(space_id)) 3150 { 3151 assert(space_id == PSParallelCompact::old_space_id, 3152 "cannot use FillClosure in the young gen"); 3153 } 3154 3155 ParMarkBitMapClosure::IterationStatus 3156 FillClosure::do_addr(HeapWord* addr, size_t size) { 3157 CollectedHeap::fill_with_objects(addr, size); 3158 HeapWord* const end = addr + size; 3159 do { 3160 _start_array->allocate_block(addr); 3161 addr += oop(addr)->size(); 3162 } while (addr < end); 3163 return ParMarkBitMap::incomplete; 3164 }