1 /* 2 * Copyright (c) 2011, 2022, Oracle and/or its affiliates. All rights reserved. 3 * Copyright (c) 2017, 2021 SAP SE. All rights reserved. 4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 5 * 6 * This code is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License version 2 only, as 8 * published by the Free Software Foundation. 9 * 10 * This code is distributed in the hope that it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 13 * version 2 for more details (a copy is included in the LICENSE file that 14 * accompanied this code). 15 * 16 * You should have received a copy of the GNU General Public License version 17 * 2 along with this work; if not, write to the Free Software Foundation, 18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 19 * 20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 21 * or visit www.oracle.com if you need additional information or have any 22 * questions. 23 * 24 */ 25 26 #include "precompiled.hpp" 27 #include "cds/metaspaceShared.hpp" 28 #include "classfile/classLoaderData.hpp" 29 #include "gc/shared/collectedHeap.hpp" 30 #include "logging/log.hpp" 31 #include "logging/logStream.hpp" 32 #include "memory/classLoaderMetaspace.hpp" 33 #include "memory/metaspace.hpp" 34 #include "memory/metaspaceCriticalAllocation.hpp" 35 #include "memory/metaspace/chunkHeaderPool.hpp" 36 #include "memory/metaspace/chunkManager.hpp" 37 #include "memory/metaspace/commitLimiter.hpp" 38 #include "memory/metaspace/internalStats.hpp" 39 #include "memory/metaspace/metaspaceAlignment.hpp" 40 #include "memory/metaspace/metaspaceCommon.hpp" 41 #include "memory/metaspace/metaspaceContext.hpp" 42 #include "memory/metaspace/metaspaceReporter.hpp" 43 #include "memory/metaspace/metaspaceSettings.hpp" 44 #include "memory/metaspace/runningCounters.hpp" 45 #include "memory/metaspace/virtualSpaceList.hpp" 46 #include "memory/metaspaceTracer.hpp" 47 #include "memory/metaspaceStats.hpp" 48 #include "memory/metaspaceUtils.hpp" 49 #include "memory/resourceArea.hpp" 50 #include "memory/universe.hpp" 51 #include "oops/compressedOops.hpp" 52 #include "prims/jvmtiExport.hpp" 53 #include "runtime/atomic.hpp" 54 #include "runtime/globals_extension.hpp" 55 #include "runtime/init.hpp" 56 #include "runtime/java.hpp" 57 #include "services/memTracker.hpp" 58 #include "utilities/copy.hpp" 59 #include "utilities/debug.hpp" 60 #include "utilities/formatBuffer.hpp" 61 #include "utilities/globalDefinitions.hpp" 62 63 using metaspace::ChunkManager; 64 using metaspace::CommitLimiter; 65 using metaspace::MetaspaceContext; 66 using metaspace::MetaspaceReporter; 67 using metaspace::RunningCounters; 68 using metaspace::VirtualSpaceList; 69 70 size_t MetaspaceUtils::used_words() { 71 return RunningCounters::used_words(); 72 } 73 74 size_t MetaspaceUtils::used_words(Metaspace::MetadataType mdtype) { 75 return mdtype == Metaspace::ClassType ? RunningCounters::used_words_class() : RunningCounters::used_words_nonclass(); 76 } 77 78 size_t MetaspaceUtils::reserved_words() { 79 return RunningCounters::reserved_words(); 80 } 81 82 size_t MetaspaceUtils::reserved_words(Metaspace::MetadataType mdtype) { 83 return mdtype == Metaspace::ClassType ? RunningCounters::reserved_words_class() : RunningCounters::reserved_words_nonclass(); 84 } 85 86 size_t MetaspaceUtils::committed_words() { 87 return RunningCounters::committed_words(); 88 } 89 90 size_t MetaspaceUtils::committed_words(Metaspace::MetadataType mdtype) { 91 return mdtype == Metaspace::ClassType ? RunningCounters::committed_words_class() : RunningCounters::committed_words_nonclass(); 92 } 93 94 // Helper for get_statistics() 95 static void get_values_for(Metaspace::MetadataType mdtype, size_t* reserved, size_t* committed, size_t* used) { 96 #define w2b(x) (x * sizeof(MetaWord)) 97 if (mdtype == Metaspace::ClassType) { 98 *reserved = w2b(RunningCounters::reserved_words_class()); 99 *committed = w2b(RunningCounters::committed_words_class()); 100 *used = w2b(RunningCounters::used_words_class()); 101 } else { 102 *reserved = w2b(RunningCounters::reserved_words_nonclass()); 103 *committed = w2b(RunningCounters::committed_words_nonclass()); 104 *used = w2b(RunningCounters::used_words_nonclass()); 105 } 106 #undef w2b 107 } 108 109 // Retrieve all statistics in one go; make sure the values are consistent. 110 MetaspaceStats MetaspaceUtils::get_statistics(Metaspace::MetadataType mdtype) { 111 112 // Consistency: 113 // This function reads three values (reserved, committed, used) from different counters. These counters 114 // may (very rarely) be out of sync. This has been a source for intermittent test errors in the past 115 // (see e.g. JDK-8237872, JDK-8151460). 116 // - reserved and committed counter are updated under protection of Metaspace_lock; an inconsistency 117 // between them can be the result of a dirty read. 118 // - used is an atomic counter updated outside any lock range; there is no way to guarantee 119 // a clean read wrt the other two values. 120 // Reading these values under lock protection would would only help for the first case. Therefore 121 // we don't bother and just re-read several times, then give up and correct the values. 122 123 size_t r = 0, c = 0, u = 0; // Note: byte values. 124 get_values_for(mdtype, &r, &c, &u); 125 int retries = 10; 126 // If the first retrieval resulted in inconsistent values, retry a bit... 127 while ((r < c || c < u) && --retries >= 0) { 128 get_values_for(mdtype, &r, &c, &u); 129 } 130 if (c < u || r < c) { // still inconsistent. 131 // ... but not endlessly. If we don't get consistent values, correct them on the fly. 132 // The logic here is that we trust the used counter - its an atomic counter and whatever we see 133 // must have been the truth once - and from that we reconstruct a likely set of committed/reserved 134 // values. 135 metaspace::InternalStats::inc_num_inconsistent_stats(); 136 if (c < u) { 137 c = align_up(u, Metaspace::commit_alignment()); 138 } 139 if (r < c) { 140 r = align_up(c, Metaspace::reserve_alignment()); 141 } 142 } 143 return MetaspaceStats(r, c, u); 144 } 145 146 MetaspaceCombinedStats MetaspaceUtils::get_combined_statistics() { 147 return MetaspaceCombinedStats(get_statistics(Metaspace::ClassType), get_statistics(Metaspace::NonClassType)); 148 } 149 150 void MetaspaceUtils::print_metaspace_change(const MetaspaceCombinedStats& pre_meta_values) { 151 // Get values now: 152 const MetaspaceCombinedStats meta_values = get_combined_statistics(); 153 154 // We print used and committed since these are the most useful at-a-glance vitals for Metaspace: 155 // - used tells you how much memory is actually used for metadata 156 // - committed tells you how much memory is committed for the purpose of metadata 157 // The difference between those two would be waste, which can have various forms (freelists, 158 // unused parts of committed chunks etc) 159 // 160 // Left out is reserved, since this is not as exciting as the first two values: for class space, 161 // it is a constant (to uninformed users, often confusingly large). For non-class space, it would 162 // be interesting since free chunks can be uncommitted, but for now it is left out. 163 164 if (Metaspace::using_class_space()) { 165 log_info(gc, metaspace)(HEAP_CHANGE_FORMAT" " 166 HEAP_CHANGE_FORMAT" " 167 HEAP_CHANGE_FORMAT, 168 HEAP_CHANGE_FORMAT_ARGS("Metaspace", 169 pre_meta_values.used(), 170 pre_meta_values.committed(), 171 meta_values.used(), 172 meta_values.committed()), 173 HEAP_CHANGE_FORMAT_ARGS("NonClass", 174 pre_meta_values.non_class_used(), 175 pre_meta_values.non_class_committed(), 176 meta_values.non_class_used(), 177 meta_values.non_class_committed()), 178 HEAP_CHANGE_FORMAT_ARGS("Class", 179 pre_meta_values.class_used(), 180 pre_meta_values.class_committed(), 181 meta_values.class_used(), 182 meta_values.class_committed())); 183 } else { 184 log_info(gc, metaspace)(HEAP_CHANGE_FORMAT, 185 HEAP_CHANGE_FORMAT_ARGS("Metaspace", 186 pre_meta_values.used(), 187 pre_meta_values.committed(), 188 meta_values.used(), 189 meta_values.committed())); 190 } 191 } 192 193 // This will print out a basic metaspace usage report but 194 // unlike print_report() is guaranteed not to lock or to walk the CLDG. 195 void MetaspaceUtils::print_basic_report(outputStream* out, size_t scale) { 196 MetaspaceReporter::print_basic_report(out, scale); 197 } 198 199 // Prints a report about the current metaspace state. 200 // Optional parts can be enabled via flags. 201 // Function will walk the CLDG and will lock the expand lock; if that is not 202 // convenient, use print_basic_report() instead. 203 void MetaspaceUtils::print_report(outputStream* out, size_t scale) { 204 const int flags = 205 (int)MetaspaceReporter::Option::ShowLoaders | 206 (int)MetaspaceReporter::Option::BreakDownByChunkType | 207 (int)MetaspaceReporter::Option::ShowClasses; 208 MetaspaceReporter::print_report(out, scale, flags); 209 } 210 211 void MetaspaceUtils::print_on(outputStream* out) { 212 213 // Used from all GCs. It first prints out totals, then, separately, the class space portion. 214 MetaspaceCombinedStats stats = get_combined_statistics(); 215 out->print_cr(" Metaspace " 216 "used " SIZE_FORMAT "K, " 217 "committed " SIZE_FORMAT "K, " 218 "reserved " SIZE_FORMAT "K", 219 stats.used()/K, 220 stats.committed()/K, 221 stats.reserved()/K); 222 223 if (Metaspace::using_class_space()) { 224 out->print_cr(" class space " 225 "used " SIZE_FORMAT "K, " 226 "committed " SIZE_FORMAT "K, " 227 "reserved " SIZE_FORMAT "K", 228 stats.class_space_stats().used()/K, 229 stats.class_space_stats().committed()/K, 230 stats.class_space_stats().reserved()/K); 231 } 232 } 233 234 #ifdef ASSERT 235 void MetaspaceUtils::verify() { 236 if (Metaspace::initialized()) { 237 238 // Verify non-class chunkmanager... 239 ChunkManager* cm = ChunkManager::chunkmanager_nonclass(); 240 cm->verify(); 241 242 // ... and space list. 243 VirtualSpaceList* vsl = VirtualSpaceList::vslist_nonclass(); 244 vsl->verify(); 245 246 if (Metaspace::using_class_space()) { 247 // If we use compressed class pointers, verify class chunkmanager... 248 cm = ChunkManager::chunkmanager_class(); 249 cm->verify(); 250 251 // ... and class spacelist. 252 vsl = VirtualSpaceList::vslist_class(); 253 vsl->verify(); 254 } 255 256 } 257 } 258 #endif 259 260 ////////////////////////////////7 261 // MetaspaceGC methods 262 263 volatile size_t MetaspaceGC::_capacity_until_GC = 0; 264 uint MetaspaceGC::_shrink_factor = 0; 265 266 // VM_CollectForMetadataAllocation is the vm operation used to GC. 267 // Within the VM operation after the GC the attempt to allocate the metadata 268 // should succeed. If the GC did not free enough space for the metaspace 269 // allocation, the HWM is increased so that another virtualspace will be 270 // allocated for the metadata. With perm gen the increase in the perm 271 // gen had bounds, MinMetaspaceExpansion and MaxMetaspaceExpansion. The 272 // metaspace policy uses those as the small and large steps for the HWM. 273 // 274 // After the GC the compute_new_size() for MetaspaceGC is called to 275 // resize the capacity of the metaspaces. The current implementation 276 // is based on the flags MinMetaspaceFreeRatio and MaxMetaspaceFreeRatio used 277 // to resize the Java heap by some GC's. New flags can be implemented 278 // if really needed. MinMetaspaceFreeRatio is used to calculate how much 279 // free space is desirable in the metaspace capacity to decide how much 280 // to increase the HWM. MaxMetaspaceFreeRatio is used to decide how much 281 // free space is desirable in the metaspace capacity before decreasing 282 // the HWM. 283 284 // Calculate the amount to increase the high water mark (HWM). 285 // Increase by a minimum amount (MinMetaspaceExpansion) so that 286 // another expansion is not requested too soon. If that is not 287 // enough to satisfy the allocation, increase by MaxMetaspaceExpansion. 288 // If that is still not enough, expand by the size of the allocation 289 // plus some. 290 size_t MetaspaceGC::delta_capacity_until_GC(size_t bytes) { 291 size_t min_delta = MinMetaspaceExpansion; 292 size_t max_delta = MaxMetaspaceExpansion; 293 size_t delta = align_up(bytes, Metaspace::commit_alignment()); 294 295 if (delta <= min_delta) { 296 delta = min_delta; 297 } else if (delta <= max_delta) { 298 // Don't want to hit the high water mark on the next 299 // allocation so make the delta greater than just enough 300 // for this allocation. 301 delta = max_delta; 302 } else { 303 // This allocation is large but the next ones are probably not 304 // so increase by the minimum. 305 delta = delta + min_delta; 306 } 307 308 assert_is_aligned(delta, Metaspace::commit_alignment()); 309 310 return delta; 311 } 312 313 size_t MetaspaceGC::capacity_until_GC() { 314 size_t value = Atomic::load_acquire(&_capacity_until_GC); 315 assert(value >= MetaspaceSize, "Not initialized properly?"); 316 return value; 317 } 318 319 // Try to increase the _capacity_until_GC limit counter by v bytes. 320 // Returns true if it succeeded. It may fail if either another thread 321 // concurrently increased the limit or the new limit would be larger 322 // than MaxMetaspaceSize. 323 // On success, optionally returns new and old metaspace capacity in 324 // new_cap_until_GC and old_cap_until_GC respectively. 325 // On error, optionally sets can_retry to indicate whether if there is 326 // actually enough space remaining to satisfy the request. 327 bool MetaspaceGC::inc_capacity_until_GC(size_t v, size_t* new_cap_until_GC, size_t* old_cap_until_GC, bool* can_retry) { 328 assert_is_aligned(v, Metaspace::commit_alignment()); 329 330 size_t old_capacity_until_GC = _capacity_until_GC; 331 size_t new_value = old_capacity_until_GC + v; 332 333 if (new_value < old_capacity_until_GC) { 334 // The addition wrapped around, set new_value to aligned max value. 335 new_value = align_down(max_uintx, Metaspace::reserve_alignment()); 336 } 337 338 if (new_value > MaxMetaspaceSize) { 339 if (can_retry != NULL) { 340 *can_retry = false; 341 } 342 return false; 343 } 344 345 if (can_retry != NULL) { 346 *can_retry = true; 347 } 348 size_t prev_value = Atomic::cmpxchg(&_capacity_until_GC, old_capacity_until_GC, new_value); 349 350 if (old_capacity_until_GC != prev_value) { 351 return false; 352 } 353 354 if (new_cap_until_GC != NULL) { 355 *new_cap_until_GC = new_value; 356 } 357 if (old_cap_until_GC != NULL) { 358 *old_cap_until_GC = old_capacity_until_GC; 359 } 360 return true; 361 } 362 363 size_t MetaspaceGC::dec_capacity_until_GC(size_t v) { 364 assert_is_aligned(v, Metaspace::commit_alignment()); 365 366 return Atomic::sub(&_capacity_until_GC, v); 367 } 368 369 void MetaspaceGC::initialize() { 370 // Set the high-water mark to MaxMetapaceSize during VM initializaton since 371 // we can't do a GC during initialization. 372 _capacity_until_GC = MaxMetaspaceSize; 373 } 374 375 void MetaspaceGC::post_initialize() { 376 // Reset the high-water mark once the VM initialization is done. 377 _capacity_until_GC = MAX2(MetaspaceUtils::committed_bytes(), MetaspaceSize); 378 } 379 380 bool MetaspaceGC::can_expand(size_t word_size, bool is_class) { 381 // Check if the compressed class space is full. 382 if (is_class && Metaspace::using_class_space()) { 383 size_t class_committed = MetaspaceUtils::committed_bytes(Metaspace::ClassType); 384 if (class_committed + word_size * BytesPerWord > CompressedClassSpaceSize) { 385 log_trace(gc, metaspace, freelist)("Cannot expand %s metaspace by " SIZE_FORMAT " words (CompressedClassSpaceSize = " SIZE_FORMAT " words)", 386 (is_class ? "class" : "non-class"), word_size, CompressedClassSpaceSize / sizeof(MetaWord)); 387 return false; 388 } 389 } 390 391 // Check if the user has imposed a limit on the metaspace memory. 392 size_t committed_bytes = MetaspaceUtils::committed_bytes(); 393 if (committed_bytes + word_size * BytesPerWord > MaxMetaspaceSize) { 394 log_trace(gc, metaspace, freelist)("Cannot expand %s metaspace by " SIZE_FORMAT " words (MaxMetaspaceSize = " SIZE_FORMAT " words)", 395 (is_class ? "class" : "non-class"), word_size, MaxMetaspaceSize / sizeof(MetaWord)); 396 return false; 397 } 398 399 return true; 400 } 401 402 size_t MetaspaceGC::allowed_expansion() { 403 size_t committed_bytes = MetaspaceUtils::committed_bytes(); 404 size_t capacity_until_gc = capacity_until_GC(); 405 406 assert(capacity_until_gc >= committed_bytes, 407 "capacity_until_gc: " SIZE_FORMAT " < committed_bytes: " SIZE_FORMAT, 408 capacity_until_gc, committed_bytes); 409 410 size_t left_until_max = MaxMetaspaceSize - committed_bytes; 411 size_t left_until_GC = capacity_until_gc - committed_bytes; 412 size_t left_to_commit = MIN2(left_until_GC, left_until_max); 413 log_trace(gc, metaspace, freelist)("allowed expansion words: " SIZE_FORMAT 414 " (left_until_max: " SIZE_FORMAT ", left_until_GC: " SIZE_FORMAT ".", 415 left_to_commit / BytesPerWord, left_until_max / BytesPerWord, left_until_GC / BytesPerWord); 416 417 return left_to_commit / BytesPerWord; 418 } 419 420 void MetaspaceGC::compute_new_size() { 421 assert(_shrink_factor <= 100, "invalid shrink factor"); 422 uint current_shrink_factor = _shrink_factor; 423 _shrink_factor = 0; 424 425 // Using committed_bytes() for used_after_gc is an overestimation, since the 426 // chunk free lists are included in committed_bytes() and the memory in an 427 // un-fragmented chunk free list is available for future allocations. 428 // However, if the chunk free lists becomes fragmented, then the memory may 429 // not be available for future allocations and the memory is therefore "in use". 430 // Including the chunk free lists in the definition of "in use" is therefore 431 // necessary. Not including the chunk free lists can cause capacity_until_GC to 432 // shrink below committed_bytes() and this has caused serious bugs in the past. 433 const size_t used_after_gc = MetaspaceUtils::committed_bytes(); 434 const size_t capacity_until_GC = MetaspaceGC::capacity_until_GC(); 435 436 const double minimum_free_percentage = MinMetaspaceFreeRatio / 100.0; 437 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 438 439 const double min_tmp = used_after_gc / maximum_used_percentage; 440 size_t minimum_desired_capacity = 441 (size_t)MIN2(min_tmp, double(MaxMetaspaceSize)); 442 // Don't shrink less than the initial generation size 443 minimum_desired_capacity = MAX2(minimum_desired_capacity, 444 MetaspaceSize); 445 446 log_trace(gc, metaspace)("MetaspaceGC::compute_new_size: "); 447 log_trace(gc, metaspace)(" minimum_free_percentage: %6.2f maximum_used_percentage: %6.2f", 448 minimum_free_percentage, maximum_used_percentage); 449 log_trace(gc, metaspace)(" used_after_gc : %6.1fKB", used_after_gc / (double) K); 450 451 size_t shrink_bytes = 0; 452 if (capacity_until_GC < minimum_desired_capacity) { 453 // If we have less capacity below the metaspace HWM, then 454 // increment the HWM. 455 size_t expand_bytes = minimum_desired_capacity - capacity_until_GC; 456 expand_bytes = align_up(expand_bytes, Metaspace::commit_alignment()); 457 // Don't expand unless it's significant 458 if (expand_bytes >= MinMetaspaceExpansion) { 459 size_t new_capacity_until_GC = 0; 460 bool succeeded = MetaspaceGC::inc_capacity_until_GC(expand_bytes, &new_capacity_until_GC); 461 assert(succeeded, "Should always successfully increment HWM when at safepoint"); 462 463 Metaspace::tracer()->report_gc_threshold(capacity_until_GC, 464 new_capacity_until_GC, 465 MetaspaceGCThresholdUpdater::ComputeNewSize); 466 log_trace(gc, metaspace)(" expanding: minimum_desired_capacity: %6.1fKB expand_bytes: %6.1fKB MinMetaspaceExpansion: %6.1fKB new metaspace HWM: %6.1fKB", 467 minimum_desired_capacity / (double) K, 468 expand_bytes / (double) K, 469 MinMetaspaceExpansion / (double) K, 470 new_capacity_until_GC / (double) K); 471 } 472 return; 473 } 474 475 // No expansion, now see if we want to shrink 476 // We would never want to shrink more than this 477 assert(capacity_until_GC >= minimum_desired_capacity, 478 SIZE_FORMAT " >= " SIZE_FORMAT, 479 capacity_until_GC, minimum_desired_capacity); 480 size_t max_shrink_bytes = capacity_until_GC - minimum_desired_capacity; 481 482 // Should shrinking be considered? 483 if (MaxMetaspaceFreeRatio < 100) { 484 const double maximum_free_percentage = MaxMetaspaceFreeRatio / 100.0; 485 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 486 const double max_tmp = used_after_gc / minimum_used_percentage; 487 size_t maximum_desired_capacity = (size_t)MIN2(max_tmp, double(MaxMetaspaceSize)); 488 maximum_desired_capacity = MAX2(maximum_desired_capacity, 489 MetaspaceSize); 490 log_trace(gc, metaspace)(" maximum_free_percentage: %6.2f minimum_used_percentage: %6.2f", 491 maximum_free_percentage, minimum_used_percentage); 492 log_trace(gc, metaspace)(" minimum_desired_capacity: %6.1fKB maximum_desired_capacity: %6.1fKB", 493 minimum_desired_capacity / (double) K, maximum_desired_capacity / (double) K); 494 495 assert(minimum_desired_capacity <= maximum_desired_capacity, 496 "sanity check"); 497 498 if (capacity_until_GC > maximum_desired_capacity) { 499 // Capacity too large, compute shrinking size 500 shrink_bytes = capacity_until_GC - maximum_desired_capacity; 501 // We don't want shrink all the way back to initSize if people call 502 // System.gc(), because some programs do that between "phases" and then 503 // we'd just have to grow the heap up again for the next phase. So we 504 // damp the shrinking: 0% on the first call, 10% on the second call, 40% 505 // on the third call, and 100% by the fourth call. But if we recompute 506 // size without shrinking, it goes back to 0%. 507 shrink_bytes = shrink_bytes / 100 * current_shrink_factor; 508 509 shrink_bytes = align_down(shrink_bytes, Metaspace::commit_alignment()); 510 511 assert(shrink_bytes <= max_shrink_bytes, 512 "invalid shrink size " SIZE_FORMAT " not <= " SIZE_FORMAT, 513 shrink_bytes, max_shrink_bytes); 514 if (current_shrink_factor == 0) { 515 _shrink_factor = 10; 516 } else { 517 _shrink_factor = MIN2(current_shrink_factor * 4, (uint) 100); 518 } 519 log_trace(gc, metaspace)(" shrinking: initThreshold: %.1fK maximum_desired_capacity: %.1fK", 520 MetaspaceSize / (double) K, maximum_desired_capacity / (double) K); 521 log_trace(gc, metaspace)(" shrink_bytes: %.1fK current_shrink_factor: %d new shrink factor: %d MinMetaspaceExpansion: %.1fK", 522 shrink_bytes / (double) K, current_shrink_factor, _shrink_factor, MinMetaspaceExpansion / (double) K); 523 } 524 } 525 526 // Don't shrink unless it's significant 527 if (shrink_bytes >= MinMetaspaceExpansion && 528 ((capacity_until_GC - shrink_bytes) >= MetaspaceSize)) { 529 size_t new_capacity_until_GC = MetaspaceGC::dec_capacity_until_GC(shrink_bytes); 530 Metaspace::tracer()->report_gc_threshold(capacity_until_GC, 531 new_capacity_until_GC, 532 MetaspaceGCThresholdUpdater::ComputeNewSize); 533 } 534 } 535 536 ////// Metaspace methods ///// 537 538 const MetaspaceTracer* Metaspace::_tracer = NULL; 539 540 bool Metaspace::initialized() { 541 return metaspace::MetaspaceContext::context_nonclass() != NULL 542 LP64_ONLY(&& (using_class_space() ? Metaspace::class_space_is_initialized() : true)); 543 } 544 545 #ifdef _LP64 546 547 void Metaspace::print_compressed_class_space(outputStream* st) { 548 if (VirtualSpaceList::vslist_class() != NULL) { 549 MetaWord* base = VirtualSpaceList::vslist_class()->base_of_first_node(); 550 size_t size = VirtualSpaceList::vslist_class()->word_size_of_first_node(); 551 MetaWord* top = base + size; 552 st->print("Compressed class space mapped at: " PTR_FORMAT "-" PTR_FORMAT ", reserved size: " SIZE_FORMAT, 553 p2i(base), p2i(top), (top - base) * BytesPerWord); 554 st->cr(); 555 } 556 } 557 558 // Given a prereserved space, use that to set up the compressed class space list. 559 void Metaspace::initialize_class_space(ReservedSpace rs) { 560 assert(rs.size() >= CompressedClassSpaceSize, 561 SIZE_FORMAT " != " SIZE_FORMAT, rs.size(), CompressedClassSpaceSize); 562 assert(using_class_space(), "Must be using class space"); 563 564 assert(rs.size() == CompressedClassSpaceSize, SIZE_FORMAT " != " SIZE_FORMAT, 565 rs.size(), CompressedClassSpaceSize); 566 assert(is_aligned(rs.base(), Metaspace::reserve_alignment()) && 567 is_aligned(rs.size(), Metaspace::reserve_alignment()), 568 "wrong alignment"); 569 570 MetaspaceContext::initialize_class_space_context(rs); 571 572 // This does currently not work because rs may be the result of a split 573 // operation and NMT seems not to be able to handle splits. 574 // Will be fixed with JDK-8243535. 575 // MemTracker::record_virtual_memory_type((address)rs.base(), mtClass); 576 577 } 578 579 // Returns true if class space has been setup (initialize_class_space). 580 bool Metaspace::class_space_is_initialized() { 581 return MetaspaceContext::context_class() != NULL; 582 } 583 584 // Reserve a range of memory at an address suitable for en/decoding narrow 585 // Klass pointers (see: CompressedClassPointers::is_valid_base()). 586 // The returned address shall both be suitable as a compressed class pointers 587 // base, and aligned to Metaspace::reserve_alignment (which is equal to or a 588 // multiple of allocation granularity). 589 // On error, returns an unreserved space. 590 ReservedSpace Metaspace::reserve_address_space_for_compressed_classes(size_t size) { 591 592 #if defined(AARCH64) || defined(PPC64) 593 const size_t alignment = Metaspace::reserve_alignment(); 594 595 // AArch64: Try to align metaspace so that we can decode a compressed 596 // klass with a single MOVK instruction. We can do this iff the 597 // compressed class base is a multiple of 4G. 598 // Additionally, above 32G, ensure the lower LogKlassAlignmentInBytes bits 599 // of the upper 32-bits of the address are zero so we can handle a shift 600 // when decoding. 601 602 // PPC64: smaller heaps up to 2g will be mapped just below 4g. Then the 603 // attempt to place the compressed class space just after the heap fails on 604 // Linux 4.1.42 and higher because the launcher is loaded at 4g 605 // (ELF_ET_DYN_BASE). In that case we reach here and search the address space 606 // below 32g to get a zerobased CCS. For simplicity we reuse the search 607 // strategy for AARCH64. 608 609 static const struct { 610 address from; 611 address to; 612 size_t increment; 613 } search_ranges[] = { 614 { (address)(4*G), (address)(32*G), 4*G, }, 615 { (address)(32*G), (address)(1024*G), (4 << LogKlassAlignmentInBytes) * G }, 616 { NULL, NULL, 0 } 617 }; 618 619 for (int i = 0; search_ranges[i].from != NULL; i ++) { 620 address a = search_ranges[i].from; 621 assert(CompressedKlassPointers::is_valid_base(a), "Sanity"); 622 while (a < search_ranges[i].to) { 623 ReservedSpace rs(size, Metaspace::reserve_alignment(), 624 os::vm_page_size(), (char*)a); 625 if (rs.is_reserved()) { 626 assert(a == (address)rs.base(), "Sanity"); 627 return rs; 628 } 629 a += search_ranges[i].increment; 630 } 631 } 632 #endif // defined(AARCH64) || defined(PPC64) 633 634 #ifdef AARCH64 635 // Note: on AARCH64, if the code above does not find any good placement, we 636 // have no recourse. We return an empty space and the VM will exit. 637 return ReservedSpace(); 638 #else 639 // Default implementation: Just reserve anywhere. 640 return ReservedSpace(size, Metaspace::reserve_alignment(), os::vm_page_size(), (char*)NULL); 641 #endif // AARCH64 642 } 643 644 #endif // _LP64 645 646 size_t Metaspace::reserve_alignment_words() { 647 return metaspace::Settings::virtual_space_node_reserve_alignment_words(); 648 } 649 650 size_t Metaspace::commit_alignment_words() { 651 return metaspace::Settings::commit_granule_words(); 652 } 653 654 void Metaspace::ergo_initialize() { 655 656 // Must happen before using any setting from Settings::--- 657 metaspace::Settings::ergo_initialize(); 658 659 // MaxMetaspaceSize and CompressedClassSpaceSize: 660 // 661 // MaxMetaspaceSize is the maximum size, in bytes, of memory we are allowed 662 // to commit for the Metaspace. 663 // It is just a number; a limit we compare against before committing. It 664 // does not have to be aligned to anything. 665 // It gets used as compare value before attempting to increase the metaspace 666 // commit charge. It defaults to max_uintx (unlimited). 667 // 668 // CompressedClassSpaceSize is the size, in bytes, of the address range we 669 // pre-reserve for the compressed class space (if we use class space). 670 // This size has to be aligned to the metaspace reserve alignment (to the 671 // size of a root chunk). It gets aligned up from whatever value the caller 672 // gave us to the next multiple of root chunk size. 673 // 674 // Note: Strictly speaking MaxMetaspaceSize and CompressedClassSpaceSize have 675 // very little to do with each other. The notion often encountered: 676 // MaxMetaspaceSize = CompressedClassSpaceSize + <non-class metadata size> 677 // is subtly wrong: MaxMetaspaceSize can besmaller than CompressedClassSpaceSize, 678 // in which case we just would not be able to fully commit the class space range. 679 // 680 // We still adjust CompressedClassSpaceSize to reasonable limits, mainly to 681 // save on reserved space, and to make ergnonomics less confusing. 682 683 MaxMetaspaceSize = MAX2(MaxMetaspaceSize, commit_alignment()); 684 685 if (UseCompressedClassPointers) { 686 // Let CCS size not be larger than 80% of MaxMetaspaceSize. Note that is 687 // grossly over-dimensioned for most usage scenarios; typical ratio of 688 // class space : non class space usage is about 1:6. With many small classes, 689 // it can get as low as 1:2. It is not a big deal though since ccs is only 690 // reserved and will be committed on demand only. 691 size_t max_ccs_size = MaxMetaspaceSize * 0.8; 692 size_t adjusted_ccs_size = MIN2(CompressedClassSpaceSize, max_ccs_size); 693 694 // CCS must be aligned to root chunk size, and be at least the size of one 695 // root chunk. 696 adjusted_ccs_size = align_up(adjusted_ccs_size, reserve_alignment()); 697 adjusted_ccs_size = MAX2(adjusted_ccs_size, reserve_alignment()); 698 699 // Note: re-adjusting may have us left with a CompressedClassSpaceSize 700 // larger than MaxMetaspaceSize for very small values of MaxMetaspaceSize. 701 // Lets just live with that, its not a big deal. 702 703 if (adjusted_ccs_size != CompressedClassSpaceSize) { 704 FLAG_SET_ERGO(CompressedClassSpaceSize, adjusted_ccs_size); 705 log_info(metaspace)("Setting CompressedClassSpaceSize to " SIZE_FORMAT ".", 706 CompressedClassSpaceSize); 707 } 708 } 709 710 // Set MetaspaceSize, MinMetaspaceExpansion and MaxMetaspaceExpansion 711 if (MetaspaceSize > MaxMetaspaceSize) { 712 MetaspaceSize = MaxMetaspaceSize; 713 } 714 715 MetaspaceSize = align_down_bounded(MetaspaceSize, commit_alignment()); 716 717 assert(MetaspaceSize <= MaxMetaspaceSize, "MetaspaceSize should be limited by MaxMetaspaceSize"); 718 719 MinMetaspaceExpansion = align_down_bounded(MinMetaspaceExpansion, commit_alignment()); 720 MaxMetaspaceExpansion = align_down_bounded(MaxMetaspaceExpansion, commit_alignment()); 721 722 } 723 724 void Metaspace::global_initialize() { 725 MetaspaceGC::initialize(); // <- since we do not prealloc init chunks anymore is this still needed? 726 727 metaspace::ChunkHeaderPool::initialize(); 728 729 if (DumpSharedSpaces) { 730 assert(!UseSharedSpaces, "sanity"); 731 MetaspaceShared::initialize_for_static_dump(); 732 } 733 734 // If UseCompressedClassPointers=1, we have two cases: 735 // a) if CDS is active (runtime, Xshare=on), it will create the class space 736 // for us, initialize it and set up CompressedKlassPointers encoding. 737 // Class space will be reserved above the mapped archives. 738 // b) if CDS either deactivated (Xshare=off) or a static dump is to be done (Xshare:dump), 739 // we will create the class space on our own. It will be placed above the java heap, 740 // since we assume it has been placed in low 741 // address regions. We may rethink this (see JDK-8244943). Failing that, 742 // it will be placed anywhere. 743 744 #if INCLUDE_CDS 745 // case (a) 746 if (UseSharedSpaces) { 747 if (!FLAG_IS_DEFAULT(CompressedClassSpaceBaseAddress)) { 748 log_warning(metaspace)("CDS active - ignoring CompressedClassSpaceBaseAddress."); 749 } 750 MetaspaceShared::initialize_runtime_shared_and_meta_spaces(); 751 // If any of the archived space fails to map, UseSharedSpaces 752 // is reset to false. 753 } 754 #endif // INCLUDE_CDS 755 756 #ifdef _LP64 757 758 if (using_class_space() && !class_space_is_initialized()) { 759 assert(!UseSharedSpaces, "CDS archive is not mapped at this point"); 760 761 // case (b) (No CDS) 762 ReservedSpace rs; 763 const size_t size = align_up(CompressedClassSpaceSize, Metaspace::reserve_alignment()); 764 address base = NULL; 765 766 // If CompressedClassSpaceBaseAddress is set, we attempt to force-map class space to 767 // the given address. This is a debug-only feature aiding tests. Due to the ASLR lottery 768 // this may fail, in which case the VM will exit after printing an appropriate message. 769 // Tests using this switch should cope with that. 770 if (CompressedClassSpaceBaseAddress != 0) { 771 base = (address)CompressedClassSpaceBaseAddress; 772 if (!is_aligned(base, Metaspace::reserve_alignment())) { 773 vm_exit_during_initialization( 774 err_msg("CompressedClassSpaceBaseAddress=" PTR_FORMAT " invalid " 775 "(must be aligned to " SIZE_FORMAT_HEX ").", 776 CompressedClassSpaceBaseAddress, Metaspace::reserve_alignment())); 777 } 778 rs = ReservedSpace(size, Metaspace::reserve_alignment(), 779 os::vm_page_size() /* large */, (char*)base); 780 if (rs.is_reserved()) { 781 log_info(metaspace)("Successfully forced class space address to " PTR_FORMAT, p2i(base)); 782 } else { 783 vm_exit_during_initialization( 784 err_msg("CompressedClassSpaceBaseAddress=" PTR_FORMAT " given, but reserving class space failed.", 785 CompressedClassSpaceBaseAddress)); 786 } 787 } 788 789 if (!rs.is_reserved()) { 790 // If UseCompressedOops=1 and the java heap has been placed in coops-friendly 791 // territory, i.e. its base is under 32G, then we attempt to place ccs 792 // right above the java heap. 793 // Otherwise the lower 32G are still free. We try to place ccs at the lowest 794 // allowed mapping address. 795 base = (UseCompressedOops && (uint64_t)CompressedOops::base() < OopEncodingHeapMax) ? 796 CompressedOops::end() : (address)HeapBaseMinAddress; 797 base = align_up(base, Metaspace::reserve_alignment()); 798 799 if (base != NULL) { 800 if (CompressedKlassPointers::is_valid_base(base)) { 801 rs = ReservedSpace(size, Metaspace::reserve_alignment(), 802 os::vm_page_size(), (char*)base); 803 } 804 } 805 } 806 807 // ...failing that, reserve anywhere, but let platform do optimized placement: 808 if (!rs.is_reserved()) { 809 rs = Metaspace::reserve_address_space_for_compressed_classes(size); 810 } 811 812 // ...failing that, give up. 813 if (!rs.is_reserved()) { 814 vm_exit_during_initialization( 815 err_msg("Could not allocate compressed class space: " SIZE_FORMAT " bytes", 816 CompressedClassSpaceSize)); 817 } 818 819 // Initialize space 820 Metaspace::initialize_class_space(rs); 821 822 // Set up compressed class pointer encoding. 823 CompressedKlassPointers::initialize((address)rs.base(), rs.size()); 824 } 825 826 #endif 827 828 // Initialize non-class virtual space list, and its chunk manager: 829 MetaspaceContext::initialize_nonclass_space_context(); 830 831 _tracer = new MetaspaceTracer(); 832 833 // We must prevent the very first address of the ccs from being used to store 834 // metadata, since that address would translate to a narrow pointer of 0, and the 835 // VM does not distinguish between "narrow 0 as in NULL" and "narrow 0 as in start 836 // of ccs". See CompressedKlassPointers::decode(). 837 // Before JEP 387 that did not happen due to the fact that every Metachunk 838 // had a header and therefore could not allocate anything at offset 0. 839 #ifdef _LP64 840 if (using_class_space()) { 841 // The simplest way to fix this is to allocate a tiny dummy chunk right at the 842 // start of ccs and do not use it for anything. 843 MetaspaceContext::context_class()->cm()->get_chunk(metaspace::chunklevel::HIGHEST_CHUNK_LEVEL); 844 } 845 #endif 846 847 #ifdef _LP64 848 if (UseCompressedClassPointers) { 849 // Note: "cds" would be a better fit but keep this for backward compatibility. 850 LogTarget(Info, gc, metaspace) lt; 851 if (lt.is_enabled()) { 852 ResourceMark rm; 853 LogStream ls(lt); 854 CDS_ONLY(MetaspaceShared::print_on(&ls);) 855 Metaspace::print_compressed_class_space(&ls); 856 CompressedKlassPointers::print_mode(&ls); 857 } 858 } 859 #endif 860 861 } 862 863 void Metaspace::post_initialize() { 864 MetaspaceGC::post_initialize(); 865 } 866 867 size_t Metaspace::max_allocation_word_size() { 868 return metaspace::chunklevel::MAX_CHUNK_WORD_SIZE; 869 } 870 871 #ifdef _LP64 872 // The largest allowed size for class space 873 size_t Metaspace::max_class_space_size() { 874 // This is a bit fuzzy. Max value of class space size depends on narrow klass pointer 875 // encoding range size and CDS, since class space shares encoding range with CDS. CDS 876 // archives are usually pretty small though, so to keep matters simple, for now we 877 // just assume a reasonable default (this is hackish; improve!). 878 const size_t slice_for_cds = M * 128; 879 assert(KlassEncodingMetaspaceMax >= (slice_for_cds * 2), "rethink this"); 880 const size_t max_class_space_size = KlassEncodingMetaspaceMax - slice_for_cds; 881 return max_class_space_size; 882 } 883 #endif // _LP64 884 885 // This version of Metaspace::allocate does not throw OOM but simply returns NULL, and 886 // is suitable for calling from non-Java threads. 887 // Callers are responsible for checking null. 888 MetaWord* Metaspace::allocate(ClassLoaderData* loader_data, size_t word_size, 889 MetaspaceObj::Type type) { 890 assert(word_size <= Metaspace::max_allocation_word_size(), 891 "allocation size too large (" SIZE_FORMAT ")", word_size); 892 893 assert(loader_data != NULL, "Should never pass around a NULL loader_data. " 894 "ClassLoaderData::the_null_class_loader_data() should have been used."); 895 896 // Deal with concurrent unloading failed allocation starvation 897 MetaspaceCriticalAllocation::block_if_concurrent_purge(); 898 899 MetadataType mdtype = (type == MetaspaceObj::ClassType) ? ClassType : NonClassType; 900 901 // Try to allocate metadata. 902 MetaWord* result = loader_data->metaspace_non_null()->allocate(word_size, mdtype); 903 904 if (result != NULL) { 905 // Zero initialize. 906 Copy::fill_to_words((HeapWord*)result, word_size, 0); 907 908 log_trace(metaspace)("Metaspace::allocate: type %d return " PTR_FORMAT ".", (int)type, p2i(result)); 909 } 910 911 return result; 912 } 913 914 MetaWord* Metaspace::allocate(ClassLoaderData* loader_data, size_t word_size, 915 MetaspaceObj::Type type, TRAPS) { 916 917 if (HAS_PENDING_EXCEPTION) { 918 assert(false, "Should not allocate with exception pending"); 919 return NULL; // caller does a CHECK_NULL too 920 } 921 922 MetaWord* result = allocate(loader_data, word_size, type); 923 924 if (result == NULL) { 925 MetadataType mdtype = (type == MetaspaceObj::ClassType) ? ClassType : NonClassType; 926 tracer()->report_metaspace_allocation_failure(loader_data, word_size, type, mdtype); 927 928 // Allocation failed. 929 if (is_init_completed()) { 930 // Only start a GC if the bootstrapping has completed. 931 // Try to clean out some heap memory and retry. This can prevent premature 932 // expansion of the metaspace. 933 result = Universe::heap()->satisfy_failed_metadata_allocation(loader_data, word_size, mdtype); 934 } 935 936 if (result == NULL) { 937 report_metadata_oome(loader_data, word_size, type, mdtype, THREAD); 938 assert(HAS_PENDING_EXCEPTION, "sanity"); 939 return NULL; 940 } 941 942 // Zero initialize. 943 Copy::fill_to_words((HeapWord*)result, word_size, 0); 944 945 log_trace(metaspace)("Metaspace::allocate: type %d return " PTR_FORMAT ".", (int)type, p2i(result)); 946 } 947 948 return result; 949 } 950 951 void Metaspace::report_metadata_oome(ClassLoaderData* loader_data, size_t word_size, MetaspaceObj::Type type, MetadataType mdtype, TRAPS) { 952 tracer()->report_metadata_oom(loader_data, word_size, type, mdtype); 953 954 // If result is still null, we are out of memory. 955 Log(gc, metaspace, freelist, oom) log; 956 if (log.is_info()) { 957 log.info("Metaspace (%s) allocation failed for size " SIZE_FORMAT, 958 is_class_space_allocation(mdtype) ? "class" : "data", word_size); 959 ResourceMark rm; 960 if (log.is_debug()) { 961 if (loader_data->metaspace_or_null() != NULL) { 962 LogStream ls(log.debug()); 963 loader_data->print_value_on(&ls); 964 } 965 } 966 LogStream ls(log.info()); 967 // In case of an OOM, log out a short but still useful report. 968 MetaspaceUtils::print_basic_report(&ls, 0); 969 } 970 971 bool out_of_compressed_class_space = false; 972 if (is_class_space_allocation(mdtype)) { 973 ClassLoaderMetaspace* metaspace = loader_data->metaspace_non_null(); 974 out_of_compressed_class_space = 975 MetaspaceUtils::committed_bytes(Metaspace::ClassType) + 976 align_up(word_size * BytesPerWord, 4 * M) > 977 CompressedClassSpaceSize; 978 } 979 980 // -XX:+HeapDumpOnOutOfMemoryError and -XX:OnOutOfMemoryError support 981 const char* space_string = out_of_compressed_class_space ? 982 "Compressed class space" : "Metaspace"; 983 984 report_java_out_of_memory(space_string); 985 986 if (JvmtiExport::should_post_resource_exhausted()) { 987 JvmtiExport::post_resource_exhausted( 988 JVMTI_RESOURCE_EXHAUSTED_OOM_ERROR, 989 space_string); 990 } 991 992 if (!is_init_completed()) { 993 vm_exit_during_initialization("OutOfMemoryError", space_string); 994 } 995 996 if (out_of_compressed_class_space) { 997 THROW_OOP(Universe::out_of_memory_error_class_metaspace()); 998 } else { 999 THROW_OOP(Universe::out_of_memory_error_metaspace()); 1000 } 1001 } 1002 1003 const char* Metaspace::metadata_type_name(Metaspace::MetadataType mdtype) { 1004 switch (mdtype) { 1005 case Metaspace::ClassType: return "Class"; 1006 case Metaspace::NonClassType: return "Metadata"; 1007 default: 1008 assert(false, "Got bad mdtype: %d", (int) mdtype); 1009 return NULL; 1010 } 1011 } 1012 1013 void Metaspace::purge() { 1014 // The MetaspaceCritical_lock is used by a concurrent GC to block out concurrent metaspace 1015 // allocations, that would starve critical metaspace allocations, that are about to throw 1016 // OOM if they fail; they need precedence for correctness. 1017 MutexLocker ml(MetaspaceCritical_lock, Mutex::_no_safepoint_check_flag); 1018 ChunkManager* cm = ChunkManager::chunkmanager_nonclass(); 1019 if (cm != NULL) { 1020 cm->purge(); 1021 } 1022 if (using_class_space()) { 1023 cm = ChunkManager::chunkmanager_class(); 1024 if (cm != NULL) { 1025 cm->purge(); 1026 } 1027 } 1028 1029 MetaspaceCriticalAllocation::satisfy(); 1030 } 1031 1032 bool Metaspace::contains(const void* ptr) { 1033 if (MetaspaceShared::is_in_shared_metaspace(ptr)) { 1034 return true; 1035 } 1036 return contains_non_shared(ptr); 1037 } 1038 1039 bool Metaspace::contains_non_shared(const void* ptr) { 1040 if (using_class_space() && VirtualSpaceList::vslist_class()->contains((MetaWord*)ptr)) { 1041 return true; 1042 } 1043 1044 return VirtualSpaceList::vslist_nonclass()->contains((MetaWord*)ptr); 1045 } --- EOF ---