1 /* 2 * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "gc_implementation/shared/adaptiveSizePolicy.hpp" 27 #include "gc_implementation/shared/gcPolicyCounters.hpp" 28 #include "gc_implementation/shared/vmGCOperations.hpp" 29 #include "memory/cardTableRS.hpp" 30 #include "memory/collectorPolicy.hpp" 31 #include "memory/gcLocker.inline.hpp" 32 #include "memory/genCollectedHeap.hpp" 33 #include "memory/generationSpec.hpp" 34 #include "memory/space.hpp" 35 #include "memory/universe.hpp" 36 #include "runtime/arguments.hpp" 37 #include "runtime/globals_extension.hpp" 38 #include "runtime/handles.inline.hpp" 39 #include "runtime/java.hpp" 40 #include "runtime/thread.inline.hpp" 41 #include "runtime/vmThread.hpp" 42 #include "utilities/macros.hpp" 43 #if INCLUDE_ALL_GCS 44 #include "gc_implementation/concurrentMarkSweep/cmsAdaptiveSizePolicy.hpp" 45 #include "gc_implementation/concurrentMarkSweep/cmsGCAdaptivePolicyCounters.hpp" 46 #endif // INCLUDE_ALL_GCS 47 48 // CollectorPolicy methods. 49 50 // Align down. If the aligning result in 0, return 'alignment'. 51 static size_t restricted_align_down(size_t size, size_t alignment) { 52 return MAX2(alignment, align_size_down_(size, alignment)); 53 } 54 55 void CollectorPolicy::initialize_flags() { 56 assert(_max_alignment >= _min_alignment, 57 err_msg("max_alignment: " SIZE_FORMAT " less than min_alignment: " SIZE_FORMAT, 58 _max_alignment, _min_alignment)); 59 assert(_max_alignment % _min_alignment == 0, 60 err_msg("max_alignment: " SIZE_FORMAT " not aligned by min_alignment: " SIZE_FORMAT, 61 _max_alignment, _min_alignment)); 62 63 if (MaxHeapSize < InitialHeapSize) { 64 vm_exit_during_initialization("Incompatible initial and maximum heap sizes specified"); 65 } 66 67 if (!is_size_aligned(MaxMetaspaceSize, _max_alignment)) { 68 FLAG_SET_ERGO(uintx, MaxMetaspaceSize, 69 restricted_align_down(MaxMetaspaceSize, _max_alignment)); 70 } 71 72 if (MetaspaceSize > MaxMetaspaceSize) { 73 FLAG_SET_ERGO(uintx, MetaspaceSize, MaxMetaspaceSize); 74 } 75 76 if (!is_size_aligned(MetaspaceSize, _min_alignment)) { 77 FLAG_SET_ERGO(uintx, MetaspaceSize, 78 restricted_align_down(MetaspaceSize, _min_alignment)); 79 } 80 81 assert(MetaspaceSize <= MaxMetaspaceSize, "Must be"); 82 83 MinMetaspaceExpansion = restricted_align_down(MinMetaspaceExpansion, _min_alignment); 84 MaxMetaspaceExpansion = restricted_align_down(MaxMetaspaceExpansion, _min_alignment); 85 86 MinHeapDeltaBytes = align_size_up(MinHeapDeltaBytes, _min_alignment); 87 88 assert(MetaspaceSize % _min_alignment == 0, "metapace alignment"); 89 assert(MaxMetaspaceSize % _max_alignment == 0, "maximum metaspace alignment"); 90 if (MetaspaceSize < 256*K) { 91 vm_exit_during_initialization("Too small initial Metaspace size"); 92 } 93 } 94 95 void CollectorPolicy::initialize_size_info() { 96 // User inputs from -mx and ms must be aligned 97 _min_heap_byte_size = align_size_up(Arguments::min_heap_size(), _min_alignment); 98 _initial_heap_byte_size = align_size_up(InitialHeapSize, _min_alignment); 99 _max_heap_byte_size = align_size_up(MaxHeapSize, _max_alignment); 100 101 // Check heap parameter properties 102 if (_initial_heap_byte_size < M) { 103 vm_exit_during_initialization("Too small initial heap"); 104 } 105 // Check heap parameter properties 106 if (_min_heap_byte_size < M) { 107 vm_exit_during_initialization("Too small minimum heap"); 108 } 109 if (_initial_heap_byte_size <= NewSize) { 110 // make sure there is at least some room in old space 111 vm_exit_during_initialization("Too small initial heap for new size specified"); 112 } 113 if (_max_heap_byte_size < _min_heap_byte_size) { 114 vm_exit_during_initialization("Incompatible minimum and maximum heap sizes specified"); 115 } 116 if (_initial_heap_byte_size < _min_heap_byte_size) { 117 vm_exit_during_initialization("Incompatible minimum and initial heap sizes specified"); 118 } 119 if (_max_heap_byte_size < _initial_heap_byte_size) { 120 vm_exit_during_initialization("Incompatible initial and maximum heap sizes specified"); 121 } 122 123 if (PrintGCDetails && Verbose) { 124 gclog_or_tty->print_cr("Minimum heap " SIZE_FORMAT " Initial heap " 125 SIZE_FORMAT " Maximum heap " SIZE_FORMAT, 126 _min_heap_byte_size, _initial_heap_byte_size, _max_heap_byte_size); 127 } 128 } 129 130 bool CollectorPolicy::use_should_clear_all_soft_refs(bool v) { 131 bool result = _should_clear_all_soft_refs; 132 set_should_clear_all_soft_refs(false); 133 return result; 134 } 135 136 GenRemSet* CollectorPolicy::create_rem_set(MemRegion whole_heap, 137 int max_covered_regions) { 138 switch (rem_set_name()) { 139 case GenRemSet::CardTable: { 140 CardTableRS* res = new CardTableRS(whole_heap, max_covered_regions); 141 return res; 142 } 143 default: 144 guarantee(false, "unrecognized GenRemSet::Name"); 145 return NULL; 146 } 147 } 148 149 void CollectorPolicy::cleared_all_soft_refs() { 150 // If near gc overhear limit, continue to clear SoftRefs. SoftRefs may 151 // have been cleared in the last collection but if the gc overhear 152 // limit continues to be near, SoftRefs should still be cleared. 153 if (size_policy() != NULL) { 154 _should_clear_all_soft_refs = size_policy()->gc_overhead_limit_near(); 155 } 156 _all_soft_refs_clear = true; 157 } 158 159 size_t CollectorPolicy::compute_max_alignment() { 160 // The card marking array and the offset arrays for old generations are 161 // committed in os pages as well. Make sure they are entirely full (to 162 // avoid partial page problems), e.g. if 512 bytes heap corresponds to 1 163 // byte entry and the os page size is 4096, the maximum heap size should 164 // be 512*4096 = 2MB aligned. 165 166 // There is only the GenRemSet in Hotspot and only the GenRemSet::CardTable 167 // is supported. 168 // Requirements of any new remembered set implementations must be added here. 169 size_t alignment = GenRemSet::max_alignment_constraint(GenRemSet::CardTable); 170 171 // Parallel GC does its own alignment of the generations to avoid requiring a 172 // large page (256M on some platforms) for the permanent generation. The 173 // other collectors should also be updated to do their own alignment and then 174 // this use of lcm() should be removed. 175 if (UseLargePages && !UseParallelGC) { 176 // in presence of large pages we have to make sure that our 177 // alignment is large page aware 178 alignment = lcm(os::large_page_size(), alignment); 179 } 180 181 return alignment; 182 } 183 184 // GenCollectorPolicy methods. 185 186 size_t GenCollectorPolicy::scale_by_NewRatio_aligned(size_t base_size) { 187 size_t x = base_size / (NewRatio+1); 188 size_t new_gen_size = x > _min_alignment ? 189 align_size_down(x, _min_alignment) : _min_alignment; 190 return new_gen_size; 191 } 192 193 size_t GenCollectorPolicy::bound_minus_alignment(size_t desired_size, 194 size_t maximum_size) { 195 size_t alignment = _min_alignment; 196 size_t max_minus = maximum_size - alignment; 197 return desired_size < max_minus ? desired_size : max_minus; 198 } 199 200 201 void GenCollectorPolicy::initialize_size_policy(size_t init_eden_size, 202 size_t init_promo_size, 203 size_t init_survivor_size) { 204 const double max_gc_pause_sec = ((double) MaxGCPauseMillis)/1000.0; 205 _size_policy = new AdaptiveSizePolicy(init_eden_size, 206 init_promo_size, 207 init_survivor_size, 208 max_gc_pause_sec, 209 GCTimeRatio); 210 } 211 212 void GenCollectorPolicy::initialize_flags() { 213 // All sizes must be multiples of the generation granularity. 214 _min_alignment = (uintx) Generation::GenGrain; 215 _max_alignment = compute_max_alignment(); 216 217 CollectorPolicy::initialize_flags(); 218 219 // All generational heaps have a youngest gen; handle those flags here. 220 221 // Adjust max size parameters 222 if (NewSize > MaxNewSize) { 223 MaxNewSize = NewSize; 224 } 225 NewSize = align_size_down(NewSize, _min_alignment); 226 MaxNewSize = align_size_down(MaxNewSize, _min_alignment); 227 228 // Check validity of heap flags 229 assert(NewSize % _min_alignment == 0, "eden space alignment"); 230 assert(MaxNewSize % _min_alignment == 0, "survivor space alignment"); 231 232 if (NewSize < 3 * _min_alignment) { 233 // make sure there room for eden and two survivor spaces 234 vm_exit_during_initialization("Too small new size specified"); 235 } 236 if (SurvivorRatio < 1 || NewRatio < 1) { 237 vm_exit_during_initialization("Invalid young gen ratio specified"); 238 } 239 } 240 241 void TwoGenerationCollectorPolicy::initialize_flags() { 242 GenCollectorPolicy::initialize_flags(); 243 244 OldSize = align_size_down(OldSize, _min_alignment); 245 246 if (FLAG_IS_CMDLINE(OldSize) && FLAG_IS_DEFAULT(NewSize)) { 247 // NewRatio will be used later to set the young generation size so we use 248 // it to calculate how big the heap should be based on the requested OldSize 249 // and NewRatio. 250 assert(NewRatio > 0, "NewRatio should have been set up earlier"); 251 size_t calculated_heapsize = (OldSize / NewRatio) * (NewRatio + 1); 252 253 calculated_heapsize = align_size_up(calculated_heapsize, _max_alignment); 254 MaxHeapSize = calculated_heapsize; 255 InitialHeapSize = calculated_heapsize; 256 } 257 MaxHeapSize = align_size_up(MaxHeapSize, _max_alignment); 258 259 // adjust max heap size if necessary 260 if (NewSize + OldSize > MaxHeapSize) { 261 if (FLAG_IS_CMDLINE(MaxHeapSize)) { 262 // Somebody has set a maximum heap size with the intention that we should not 263 // exceed it. Adjust New/OldSize as necessary. 264 uintx calculated_size = NewSize + OldSize; 265 double shrink_factor = (double) MaxHeapSize / calculated_size; 266 // align 267 NewSize = align_size_down((uintx) (NewSize * shrink_factor), _min_alignment); 268 // OldSize is already aligned because above we aligned MaxHeapSize to 269 // _max_alignment, and we just made sure that NewSize is aligned to 270 // _min_alignment. In initialize_flags() we verified that _max_alignment 271 // is a multiple of _min_alignment. 272 OldSize = MaxHeapSize - NewSize; 273 } else { 274 MaxHeapSize = NewSize + OldSize; 275 } 276 } 277 // need to do this again 278 MaxHeapSize = align_size_up(MaxHeapSize, _max_alignment); 279 280 // adjust max heap size if necessary 281 if (NewSize + OldSize > MaxHeapSize) { 282 if (FLAG_IS_CMDLINE(MaxHeapSize)) { 283 // somebody set a maximum heap size with the intention that we should not 284 // exceed it. Adjust New/OldSize as necessary. 285 uintx calculated_size = NewSize + OldSize; 286 double shrink_factor = (double) MaxHeapSize / calculated_size; 287 // align 288 NewSize = align_size_down((uintx) (NewSize * shrink_factor), _min_alignment); 289 // OldSize is already aligned because above we aligned MaxHeapSize to 290 // _max_alignment, and we just made sure that NewSize is aligned to 291 // _min_alignment. In initialize_flags() we verified that _max_alignment 292 // is a multiple of _min_alignment. 293 OldSize = MaxHeapSize - NewSize; 294 } else { 295 MaxHeapSize = NewSize + OldSize; 296 } 297 } 298 // need to do this again 299 MaxHeapSize = align_size_up(MaxHeapSize, _max_alignment); 300 301 always_do_update_barrier = UseConcMarkSweepGC; 302 303 // Check validity of heap flags 304 assert(OldSize % _min_alignment == 0, "old space alignment"); 305 assert(MaxHeapSize % _max_alignment == 0, "maximum heap alignment"); 306 } 307 308 // Values set on the command line win over any ergonomically 309 // set command line parameters. 310 // Ergonomic choice of parameters are done before this 311 // method is called. Values for command line parameters such as NewSize 312 // and MaxNewSize feed those ergonomic choices into this method. 313 // This method makes the final generation sizings consistent with 314 // themselves and with overall heap sizings. 315 // In the absence of explicitly set command line flags, policies 316 // such as the use of NewRatio are used to size the generation. 317 void GenCollectorPolicy::initialize_size_info() { 318 CollectorPolicy::initialize_size_info(); 319 320 // _min_alignment is used for alignment within a generation. 321 // There is additional alignment done down stream for some 322 // collectors that sometimes causes unwanted rounding up of 323 // generations sizes. 324 325 // Determine maximum size of gen0 326 327 size_t max_new_size = 0; 328 if (FLAG_IS_CMDLINE(MaxNewSize) || FLAG_IS_ERGO(MaxNewSize)) { 329 if (MaxNewSize < _min_alignment) { 330 max_new_size = _min_alignment; 331 } 332 if (MaxNewSize >= _max_heap_byte_size) { 333 max_new_size = align_size_down(_max_heap_byte_size - _min_alignment, 334 _min_alignment); 335 warning("MaxNewSize (" SIZE_FORMAT "k) is equal to or " 336 "greater than the entire heap (" SIZE_FORMAT "k). A " 337 "new generation size of " SIZE_FORMAT "k will be used.", 338 MaxNewSize/K, _max_heap_byte_size/K, max_new_size/K); 339 } else { 340 max_new_size = align_size_down(MaxNewSize, _min_alignment); 341 } 342 343 // The case for FLAG_IS_ERGO(MaxNewSize) could be treated 344 // specially at this point to just use an ergonomically set 345 // MaxNewSize to set max_new_size. For cases with small 346 // heaps such a policy often did not work because the MaxNewSize 347 // was larger than the entire heap. The interpretation given 348 // to ergonomically set flags is that the flags are set 349 // by different collectors for their own special needs but 350 // are not allowed to badly shape the heap. This allows the 351 // different collectors to decide what's best for themselves 352 // without having to factor in the overall heap shape. It 353 // can be the case in the future that the collectors would 354 // only make "wise" ergonomics choices and this policy could 355 // just accept those choices. The choices currently made are 356 // not always "wise". 357 } else { 358 max_new_size = scale_by_NewRatio_aligned(_max_heap_byte_size); 359 // Bound the maximum size by NewSize below (since it historically 360 // would have been NewSize and because the NewRatio calculation could 361 // yield a size that is too small) and bound it by MaxNewSize above. 362 // Ergonomics plays here by previously calculating the desired 363 // NewSize and MaxNewSize. 364 max_new_size = MIN2(MAX2(max_new_size, NewSize), MaxNewSize); 365 } 366 assert(max_new_size > 0, "All paths should set max_new_size"); 367 368 // Given the maximum gen0 size, determine the initial and 369 // minimum gen0 sizes. 370 371 if (_max_heap_byte_size == _min_heap_byte_size) { 372 // The maximum and minimum heap sizes are the same so 373 // the generations minimum and initial must be the 374 // same as its maximum. 375 _min_gen0_size = max_new_size; 376 _initial_gen0_size = max_new_size; 377 _max_gen0_size = max_new_size; 378 } else { 379 size_t desired_new_size = 0; 380 if (!FLAG_IS_DEFAULT(NewSize)) { 381 // If NewSize is set ergonomically (for example by cms), it 382 // would make sense to use it. If it is used, also use it 383 // to set the initial size. Although there is no reason 384 // the minimum size and the initial size have to be the same, 385 // the current implementation gets into trouble during the calculation 386 // of the tenured generation sizes if they are different. 387 // Note that this makes the initial size and the minimum size 388 // generally small compared to the NewRatio calculation. 389 _min_gen0_size = NewSize; 390 desired_new_size = NewSize; 391 max_new_size = MAX2(max_new_size, NewSize); 392 } else { 393 // For the case where NewSize is the default, use NewRatio 394 // to size the minimum and initial generation sizes. 395 // Use the default NewSize as the floor for these values. If 396 // NewRatio is overly large, the resulting sizes can be too 397 // small. 398 _min_gen0_size = MAX2(scale_by_NewRatio_aligned(_min_heap_byte_size), NewSize); 399 desired_new_size = 400 MAX2(scale_by_NewRatio_aligned(_initial_heap_byte_size), NewSize); 401 } 402 403 assert(_min_gen0_size > 0, "Sanity check"); 404 _initial_gen0_size = desired_new_size; 405 _max_gen0_size = max_new_size; 406 407 // At this point the desirable initial and minimum sizes have been 408 // determined without regard to the maximum sizes. 409 410 // Bound the sizes by the corresponding overall heap sizes. 411 _min_gen0_size = bound_minus_alignment(_min_gen0_size, _min_heap_byte_size); 412 _initial_gen0_size = bound_minus_alignment(_initial_gen0_size, _initial_heap_byte_size); 413 _max_gen0_size = bound_minus_alignment(_max_gen0_size, _max_heap_byte_size); 414 415 // At this point all three sizes have been checked against the 416 // maximum sizes but have not been checked for consistency 417 // among the three. 418 419 // Final check min <= initial <= max 420 _min_gen0_size = MIN2(_min_gen0_size, _max_gen0_size); 421 _initial_gen0_size = MAX2(MIN2(_initial_gen0_size, _max_gen0_size), _min_gen0_size); 422 _min_gen0_size = MIN2(_min_gen0_size, _initial_gen0_size); 423 } 424 425 if (PrintGCDetails && Verbose) { 426 gclog_or_tty->print_cr("1: Minimum gen0 " SIZE_FORMAT " Initial gen0 " 427 SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT, 428 _min_gen0_size, _initial_gen0_size, _max_gen0_size); 429 } 430 } 431 432 // Call this method during the sizing of the gen1 to make 433 // adjustments to gen0 because of gen1 sizing policy. gen0 initially has 434 // the most freedom in sizing because it is done before the 435 // policy for gen1 is applied. Once gen1 policies have been applied, 436 // there may be conflicts in the shape of the heap and this method 437 // is used to make the needed adjustments. The application of the 438 // policies could be more sophisticated (iterative for example) but 439 // keeping it simple also seems a worthwhile goal. 440 bool TwoGenerationCollectorPolicy::adjust_gen0_sizes(size_t* gen0_size_ptr, 441 size_t* gen1_size_ptr, 442 const size_t heap_size, 443 const size_t min_gen1_size) { 444 bool result = false; 445 446 if ((*gen1_size_ptr + *gen0_size_ptr) > heap_size) { 447 if ((heap_size < (*gen0_size_ptr + min_gen1_size)) && 448 (heap_size >= min_gen1_size + _min_alignment)) { 449 // Adjust gen0 down to accommodate min_gen1_size 450 *gen0_size_ptr = 451 MAX2((uintx)align_size_down(heap_size - min_gen1_size, _min_alignment), 452 _min_alignment); 453 assert(*gen0_size_ptr > 0, "Min gen0 is too large"); 454 result = true; 455 } else { 456 *gen1_size_ptr = 457 MAX2((uintx)align_size_down(heap_size - *gen0_size_ptr, _min_alignment), 458 _min_alignment); 459 } 460 } 461 return result; 462 } 463 464 // Minimum sizes of the generations may be different than 465 // the initial sizes. An inconsistency is permitted here 466 // in the total size that can be specified explicitly by 467 // command line specification of OldSize and NewSize and 468 // also a command line specification of -Xms. Issue a warning 469 // but allow the values to pass. 470 471 void TwoGenerationCollectorPolicy::initialize_size_info() { 472 GenCollectorPolicy::initialize_size_info(); 473 474 // At this point the minimum, initial and maximum sizes 475 // of the overall heap and of gen0 have been determined. 476 // The maximum gen1 size can be determined from the maximum gen0 477 // and maximum heap size since no explicit flags exist 478 // for setting the gen1 maximum. 479 _max_gen1_size = _max_heap_byte_size - _max_gen0_size; 480 _max_gen1_size = 481 MAX2((uintx)align_size_down(_max_gen1_size, _min_alignment), _min_alignment); 482 483 // If no explicit command line flag has been set for the 484 // gen1 size, use what is left for gen1. 485 if (FLAG_IS_DEFAULT(OldSize) || FLAG_IS_ERGO(OldSize)) { 486 // The user has not specified any value or ergonomics 487 // has chosen a value (which may or may not be consistent 488 // with the overall heap size). In either case make 489 // the minimum, maximum and initial sizes consistent 490 // with the gen0 sizes and the overall heap sizes. 491 assert(_min_heap_byte_size > _min_gen0_size, 492 "gen0 has an unexpected minimum size"); 493 _min_gen1_size = _min_heap_byte_size - _min_gen0_size; 494 _min_gen1_size = MAX2((uintx)align_size_down(_min_gen1_size, _min_alignment), 495 _min_alignment); 496 _initial_gen1_size = _initial_heap_byte_size - _initial_gen0_size; 497 _initial_gen1_size = MAX2((uintx)align_size_down(_initial_gen1_size, _min_alignment), 498 _min_alignment); 499 } else { 500 // OldSize has been explicitly set on the command line. Use the 501 // OldSize and then determine the consequences. 502 _min_gen1_size = OldSize; 503 _initial_gen1_size = OldSize; 504 505 // If the user has explicitly set an OldSize that is inconsistent 506 // with other command line flags, issue a warning. 507 // The generation minimums and the overall heap minimum should 508 // be within one heap alignment. 509 if ((_min_gen1_size + _min_gen0_size + _min_alignment) < _min_heap_byte_size) { 510 warning("Inconsistency between minimum heap size and minimum " 511 "generation sizes: using minimum heap = " SIZE_FORMAT, 512 _min_heap_byte_size); 513 } 514 if (OldSize > _max_gen1_size) { 515 warning("Inconsistency between maximum heap size and maximum " 516 "generation sizes: using maximum heap = " SIZE_FORMAT 517 " -XX:OldSize flag is being ignored", 518 _max_heap_byte_size); 519 } 520 // If there is an inconsistency between the OldSize and the minimum and/or 521 // initial size of gen0, since OldSize was explicitly set, OldSize wins. 522 if (adjust_gen0_sizes(&_min_gen0_size, &_min_gen1_size, 523 _min_heap_byte_size, OldSize)) { 524 if (PrintGCDetails && Verbose) { 525 gclog_or_tty->print_cr("2: Minimum gen0 " SIZE_FORMAT " Initial gen0 " 526 SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT, 527 _min_gen0_size, _initial_gen0_size, _max_gen0_size); 528 } 529 } 530 // The same as above for the old gen initial size 531 if (adjust_gen0_sizes(&_initial_gen0_size, &_initial_gen1_size, 532 _initial_heap_byte_size, OldSize)) { 533 if (PrintGCDetails && Verbose) { 534 gclog_or_tty->print_cr("3: Minimum gen0 " SIZE_FORMAT " Initial gen0 " 535 SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT, 536 _min_gen0_size, _initial_gen0_size, _max_gen0_size); 537 } 538 } 539 } 540 // Enforce the maximum gen1 size. 541 _min_gen1_size = MIN2(_min_gen1_size, _max_gen1_size); 542 543 // Check that min gen1 <= initial gen1 <= max gen1 544 _initial_gen1_size = MAX2(_initial_gen1_size, _min_gen1_size); 545 _initial_gen1_size = MIN2(_initial_gen1_size, _max_gen1_size); 546 547 if (PrintGCDetails && Verbose) { 548 gclog_or_tty->print_cr("Minimum gen1 " SIZE_FORMAT " Initial gen1 " 549 SIZE_FORMAT " Maximum gen1 " SIZE_FORMAT, 550 _min_gen1_size, _initial_gen1_size, _max_gen1_size); 551 } 552 } 553 554 HeapWord* GenCollectorPolicy::mem_allocate_work(size_t size, 555 bool is_tlab, 556 bool* gc_overhead_limit_was_exceeded) { 557 GenCollectedHeap *gch = GenCollectedHeap::heap(); 558 559 debug_only(gch->check_for_valid_allocation_state()); 560 assert(gch->no_gc_in_progress(), "Allocation during gc not allowed"); 561 562 // In general gc_overhead_limit_was_exceeded should be false so 563 // set it so here and reset it to true only if the gc time 564 // limit is being exceeded as checked below. 565 *gc_overhead_limit_was_exceeded = false; 566 567 HeapWord* result = NULL; 568 569 // Loop until the allocation is satisfied, or unsatisfied after GC. 570 for (int try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) { 571 HandleMark hm; // discard any handles allocated in each iteration 572 573 // First allocation attempt is lock-free. 574 Generation *gen0 = gch->get_gen(0); 575 assert(gen0->supports_inline_contig_alloc(), 576 "Otherwise, must do alloc within heap lock"); 577 if (gen0->should_allocate(size, is_tlab)) { 578 result = gen0->par_allocate(size, is_tlab); 579 if (result != NULL) { 580 assert(gch->is_in_reserved(result), "result not in heap"); 581 return result; 582 } 583 } 584 unsigned int gc_count_before; // read inside the Heap_lock locked region 585 { 586 MutexLocker ml(Heap_lock); 587 if (PrintGC && Verbose) { 588 gclog_or_tty->print_cr("TwoGenerationCollectorPolicy::mem_allocate_work:" 589 " attempting locked slow path allocation"); 590 } 591 // Note that only large objects get a shot at being 592 // allocated in later generations. 593 bool first_only = ! should_try_older_generation_allocation(size); 594 595 result = gch->attempt_allocation(size, is_tlab, first_only); 596 if (result != NULL) { 597 assert(gch->is_in_reserved(result), "result not in heap"); 598 return result; 599 } 600 601 if (GC_locker::is_active_and_needs_gc()) { 602 if (is_tlab) { 603 return NULL; // Caller will retry allocating individual object 604 } 605 if (!gch->is_maximal_no_gc()) { 606 // Try and expand heap to satisfy request 607 result = expand_heap_and_allocate(size, is_tlab); 608 // result could be null if we are out of space 609 if (result != NULL) { 610 return result; 611 } 612 } 613 614 if (gclocker_stalled_count > GCLockerRetryAllocationCount) { 615 return NULL; // we didn't get to do a GC and we didn't get any memory 616 } 617 618 // If this thread is not in a jni critical section, we stall 619 // the requestor until the critical section has cleared and 620 // GC allowed. When the critical section clears, a GC is 621 // initiated by the last thread exiting the critical section; so 622 // we retry the allocation sequence from the beginning of the loop, 623 // rather than causing more, now probably unnecessary, GC attempts. 624 JavaThread* jthr = JavaThread::current(); 625 if (!jthr->in_critical()) { 626 MutexUnlocker mul(Heap_lock); 627 // Wait for JNI critical section to be exited 628 GC_locker::stall_until_clear(); 629 gclocker_stalled_count += 1; 630 continue; 631 } else { 632 if (CheckJNICalls) { 633 fatal("Possible deadlock due to allocating while" 634 " in jni critical section"); 635 } 636 return NULL; 637 } 638 } 639 640 // Read the gc count while the heap lock is held. 641 gc_count_before = Universe::heap()->total_collections(); 642 } 643 644 VM_GenCollectForAllocation op(size, 645 is_tlab, 646 gc_count_before); 647 VMThread::execute(&op); 648 if (op.prologue_succeeded()) { 649 result = op.result(); 650 if (op.gc_locked()) { 651 assert(result == NULL, "must be NULL if gc_locked() is true"); 652 continue; // retry and/or stall as necessary 653 } 654 655 // Allocation has failed and a collection 656 // has been done. If the gc time limit was exceeded the 657 // this time, return NULL so that an out-of-memory 658 // will be thrown. Clear gc_overhead_limit_exceeded 659 // so that the overhead exceeded does not persist. 660 661 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded(); 662 const bool softrefs_clear = all_soft_refs_clear(); 663 664 if (limit_exceeded && softrefs_clear) { 665 *gc_overhead_limit_was_exceeded = true; 666 size_policy()->set_gc_overhead_limit_exceeded(false); 667 if (op.result() != NULL) { 668 CollectedHeap::fill_with_object(op.result(), size); 669 } 670 return NULL; 671 } 672 assert(result == NULL || gch->is_in_reserved(result), 673 "result not in heap"); 674 return result; 675 } 676 677 // Give a warning if we seem to be looping forever. 678 if ((QueuedAllocationWarningCount > 0) && 679 (try_count % QueuedAllocationWarningCount == 0)) { 680 warning("TwoGenerationCollectorPolicy::mem_allocate_work retries %d times \n\t" 681 " size=%d %s", try_count, size, is_tlab ? "(TLAB)" : ""); 682 } 683 } 684 } 685 686 HeapWord* GenCollectorPolicy::expand_heap_and_allocate(size_t size, 687 bool is_tlab) { 688 GenCollectedHeap *gch = GenCollectedHeap::heap(); 689 HeapWord* result = NULL; 690 for (int i = number_of_generations() - 1; i >= 0 && result == NULL; i--) { 691 Generation *gen = gch->get_gen(i); 692 if (gen->should_allocate(size, is_tlab)) { 693 result = gen->expand_and_allocate(size, is_tlab); 694 } 695 } 696 assert(result == NULL || gch->is_in_reserved(result), "result not in heap"); 697 return result; 698 } 699 700 HeapWord* GenCollectorPolicy::satisfy_failed_allocation(size_t size, 701 bool is_tlab) { 702 GenCollectedHeap *gch = GenCollectedHeap::heap(); 703 GCCauseSetter x(gch, GCCause::_allocation_failure); 704 HeapWord* result = NULL; 705 706 assert(size != 0, "Precondition violated"); 707 if (GC_locker::is_active_and_needs_gc()) { 708 // GC locker is active; instead of a collection we will attempt 709 // to expand the heap, if there's room for expansion. 710 if (!gch->is_maximal_no_gc()) { 711 result = expand_heap_and_allocate(size, is_tlab); 712 } 713 return result; // could be null if we are out of space 714 } else if (!gch->incremental_collection_will_fail(false /* don't consult_young */)) { 715 // Do an incremental collection. 716 gch->do_collection(false /* full */, 717 false /* clear_all_soft_refs */, 718 size /* size */, 719 is_tlab /* is_tlab */, 720 number_of_generations() - 1 /* max_level */); 721 } else { 722 if (Verbose && PrintGCDetails) { 723 gclog_or_tty->print(" :: Trying full because partial may fail :: "); 724 } 725 // Try a full collection; see delta for bug id 6266275 726 // for the original code and why this has been simplified 727 // with from-space allocation criteria modified and 728 // such allocation moved out of the safepoint path. 729 gch->do_collection(true /* full */, 730 false /* clear_all_soft_refs */, 731 size /* size */, 732 is_tlab /* is_tlab */, 733 number_of_generations() - 1 /* max_level */); 734 } 735 736 result = gch->attempt_allocation(size, is_tlab, false /*first_only*/); 737 738 if (result != NULL) { 739 assert(gch->is_in_reserved(result), "result not in heap"); 740 return result; 741 } 742 743 // OK, collection failed, try expansion. 744 result = expand_heap_and_allocate(size, is_tlab); 745 if (result != NULL) { 746 return result; 747 } 748 749 // If we reach this point, we're really out of memory. Try every trick 750 // we can to reclaim memory. Force collection of soft references. Force 751 // a complete compaction of the heap. Any additional methods for finding 752 // free memory should be here, especially if they are expensive. If this 753 // attempt fails, an OOM exception will be thrown. 754 { 755 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted 756 757 gch->do_collection(true /* full */, 758 true /* clear_all_soft_refs */, 759 size /* size */, 760 is_tlab /* is_tlab */, 761 number_of_generations() - 1 /* max_level */); 762 } 763 764 result = gch->attempt_allocation(size, is_tlab, false /* first_only */); 765 if (result != NULL) { 766 assert(gch->is_in_reserved(result), "result not in heap"); 767 return result; 768 } 769 770 assert(!should_clear_all_soft_refs(), 771 "Flag should have been handled and cleared prior to this point"); 772 773 // What else? We might try synchronous finalization later. If the total 774 // space available is large enough for the allocation, then a more 775 // complete compaction phase than we've tried so far might be 776 // appropriate. 777 return NULL; 778 } 779 780 MetaWord* CollectorPolicy::satisfy_failed_metadata_allocation( 781 ClassLoaderData* loader_data, 782 size_t word_size, 783 Metaspace::MetadataType mdtype) { 784 uint loop_count = 0; 785 uint gc_count = 0; 786 uint full_gc_count = 0; 787 788 assert(!Heap_lock->owned_by_self(), "Should not be holding the Heap_lock"); 789 790 do { 791 MetaWord* result = NULL; 792 if (GC_locker::is_active_and_needs_gc()) { 793 // If the GC_locker is active, just expand and allocate. 794 // If that does not succeed, wait if this thread is not 795 // in a critical section itself. 796 result = 797 loader_data->metaspace_non_null()->expand_and_allocate(word_size, 798 mdtype); 799 if (result != NULL) { 800 return result; 801 } 802 JavaThread* jthr = JavaThread::current(); 803 if (!jthr->in_critical()) { 804 // Wait for JNI critical section to be exited 805 GC_locker::stall_until_clear(); 806 // The GC invoked by the last thread leaving the critical 807 // section will be a young collection and a full collection 808 // is (currently) needed for unloading classes so continue 809 // to the next iteration to get a full GC. 810 continue; 811 } else { 812 if (CheckJNICalls) { 813 fatal("Possible deadlock due to allocating while" 814 " in jni critical section"); 815 } 816 return NULL; 817 } 818 } 819 820 { // Need lock to get self consistent gc_count's 821 MutexLocker ml(Heap_lock); 822 gc_count = Universe::heap()->total_collections(); 823 full_gc_count = Universe::heap()->total_full_collections(); 824 } 825 826 // Generate a VM operation 827 VM_CollectForMetadataAllocation op(loader_data, 828 word_size, 829 mdtype, 830 gc_count, 831 full_gc_count, 832 GCCause::_metadata_GC_threshold); 833 VMThread::execute(&op); 834 835 // If GC was locked out, try again. Check 836 // before checking success because the prologue 837 // could have succeeded and the GC still have 838 // been locked out. 839 if (op.gc_locked()) { 840 continue; 841 } 842 843 if (op.prologue_succeeded()) { 844 return op.result(); 845 } 846 loop_count++; 847 if ((QueuedAllocationWarningCount > 0) && 848 (loop_count % QueuedAllocationWarningCount == 0)) { 849 warning("satisfy_failed_metadata_allocation() retries %d times \n\t" 850 " size=%d", loop_count, word_size); 851 } 852 } while (true); // Until a GC is done 853 } 854 855 // Return true if any of the following is true: 856 // . the allocation won't fit into the current young gen heap 857 // . gc locker is occupied (jni critical section) 858 // . heap memory is tight -- the most recent previous collection 859 // was a full collection because a partial collection (would 860 // have) failed and is likely to fail again 861 bool GenCollectorPolicy::should_try_older_generation_allocation( 862 size_t word_size) const { 863 GenCollectedHeap* gch = GenCollectedHeap::heap(); 864 size_t gen0_capacity = gch->get_gen(0)->capacity_before_gc(); 865 return (word_size > heap_word_size(gen0_capacity)) 866 || GC_locker::is_active_and_needs_gc() 867 || gch->incremental_collection_failed(); 868 } 869 870 871 // 872 // MarkSweepPolicy methods 873 // 874 875 MarkSweepPolicy::MarkSweepPolicy() { 876 initialize_all(); 877 } 878 879 void MarkSweepPolicy::initialize_generations() { 880 _generations = NEW_C_HEAP_ARRAY3(GenerationSpecPtr, number_of_generations(), mtGC, 0, AllocFailStrategy::RETURN_NULL); 881 if (_generations == NULL) { 882 vm_exit_during_initialization("Unable to allocate gen spec"); 883 } 884 885 if (UseParNewGC) { 886 _generations[0] = new GenerationSpec(Generation::ParNew, _initial_gen0_size, _max_gen0_size); 887 } else { 888 _generations[0] = new GenerationSpec(Generation::DefNew, _initial_gen0_size, _max_gen0_size); 889 } 890 _generations[1] = new GenerationSpec(Generation::MarkSweepCompact, _initial_gen1_size, _max_gen1_size); 891 892 if (_generations[0] == NULL || _generations[1] == NULL) { 893 vm_exit_during_initialization("Unable to allocate gen spec"); 894 } 895 } 896 897 void MarkSweepPolicy::initialize_gc_policy_counters() { 898 // initialize the policy counters - 2 collectors, 3 generations 899 if (UseParNewGC) { 900 _gc_policy_counters = new GCPolicyCounters("ParNew:MSC", 2, 3); 901 } else { 902 _gc_policy_counters = new GCPolicyCounters("Copy:MSC", 2, 3); 903 } 904 }