1 /*
   2  * Copyright (c) 2011, 2024, Oracle and/or its affiliates. All rights reserved.
   3  * Copyright (c) 2017, 2021 SAP SE. All rights reserved.
   4  * Copyright (c) 2023, Red Hat, Inc. All rights reserved.
   5  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   6  *
   7  * This code is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU General Public License version 2 only, as
   9  * published by the Free Software Foundation.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  *
  25  */
  26 
  27 #include "precompiled.hpp"
  28 #include "cds/cdsConfig.hpp"
  29 #include "cds/metaspaceShared.hpp"
  30 #include "classfile/classLoaderData.hpp"
  31 #include "gc/shared/collectedHeap.hpp"
  32 #include "logging/log.hpp"
  33 #include "logging/logStream.hpp"
  34 #include "memory/classLoaderMetaspace.hpp"
  35 #include "memory/metaspace.hpp"
  36 #include "memory/metaspace/chunkHeaderPool.hpp"
  37 #include "memory/metaspace/chunkManager.hpp"
  38 #include "memory/metaspace/commitLimiter.hpp"
  39 #include "memory/metaspace/internalStats.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/metaspaceCriticalAllocation.hpp"
  47 #include "memory/metaspaceStats.hpp"
  48 #include "memory/metaspaceTracer.hpp"
  49 #include "memory/metaspaceUtils.hpp"
  50 #include "memory/resourceArea.hpp"
  51 #include "memory/universe.hpp"
  52 #include "nmt/memTracker.hpp"
  53 #include "oops/compressedKlass.inline.hpp"
  54 #include "oops/compressedOops.hpp"
  55 #include "prims/jvmtiExport.hpp"
  56 #include "runtime/atomic.hpp"
  57 #include "runtime/globals_extension.hpp"
  58 #include "runtime/init.hpp"
  59 #include "runtime/java.hpp"
  60 #include "utilities/copy.hpp"
  61 #include "utilities/debug.hpp"
  62 #include "utilities/formatBuffer.hpp"
  63 #include "utilities/globalDefinitions.hpp"
  64 #include "virtualspace.hpp"
  65 
  66 using metaspace::ChunkManager;
  67 using metaspace::CommitLimiter;
  68 using metaspace::MetaspaceContext;
  69 using metaspace::MetaspaceReporter;
  70 using metaspace::RunningCounters;
  71 using metaspace::VirtualSpaceList;
  72 
  73 size_t MetaspaceUtils::used_words() {
  74   return RunningCounters::used_words();
  75 }
  76 
  77 size_t MetaspaceUtils::used_words(Metaspace::MetadataType mdtype) {
  78   return mdtype == Metaspace::ClassType ? RunningCounters::used_words_class() : RunningCounters::used_words_nonclass();
  79 }
  80 
  81 size_t MetaspaceUtils::reserved_words() {
  82   return RunningCounters::reserved_words();
  83 }
  84 
  85 size_t MetaspaceUtils::reserved_words(Metaspace::MetadataType mdtype) {
  86   return mdtype == Metaspace::ClassType ? RunningCounters::reserved_words_class() : RunningCounters::reserved_words_nonclass();
  87 }
  88 
  89 size_t MetaspaceUtils::committed_words() {
  90   return RunningCounters::committed_words();
  91 }
  92 
  93 size_t MetaspaceUtils::committed_words(Metaspace::MetadataType mdtype) {
  94   return mdtype == Metaspace::ClassType ? RunningCounters::committed_words_class() : RunningCounters::committed_words_nonclass();
  95 }
  96 
  97 // Helper for get_statistics()
  98 static void get_values_for(Metaspace::MetadataType mdtype, size_t* reserved, size_t* committed, size_t* used) {
  99 #define w2b(x) (x * sizeof(MetaWord))
 100   if (mdtype == Metaspace::ClassType) {
 101     *reserved = w2b(RunningCounters::reserved_words_class());
 102     *committed = w2b(RunningCounters::committed_words_class());
 103     *used = w2b(RunningCounters::used_words_class());
 104   } else {
 105     *reserved = w2b(RunningCounters::reserved_words_nonclass());
 106     *committed = w2b(RunningCounters::committed_words_nonclass());
 107     *used = w2b(RunningCounters::used_words_nonclass());
 108   }
 109 #undef w2b
 110 }
 111 
 112 // Retrieve all statistics in one go; make sure the values are consistent.
 113 MetaspaceStats MetaspaceUtils::get_statistics(Metaspace::MetadataType mdtype) {
 114 
 115   // Consistency:
 116   // This function reads three values (reserved, committed, used) from different counters. These counters
 117   // may (very rarely) be out of sync. This has been a source for intermittent test errors in the past
 118   //  (see e.g. JDK-8237872, JDK-8151460).
 119   // - reserved and committed counter are updated under protection of Metaspace_lock; an inconsistency
 120   //   between them can be the result of a dirty read.
 121   // - used is an atomic counter updated outside any lock range; there is no way to guarantee
 122   //   a clean read wrt the other two values.
 123   // Reading these values under lock protection would would only help for the first case. Therefore
 124   //   we don't bother and just re-read several times, then give up and correct the values.
 125 
 126   size_t r = 0, c = 0, u = 0; // Note: byte values.
 127   get_values_for(mdtype, &r, &c, &u);
 128   int retries = 10;
 129   // If the first retrieval resulted in inconsistent values, retry a bit...
 130   while ((r < c || c < u) && --retries >= 0) {
 131     get_values_for(mdtype, &r, &c, &u);
 132   }
 133   if (c < u || r < c) { // still inconsistent.
 134     // ... but not endlessly. If we don't get consistent values, correct them on the fly.
 135     // The logic here is that we trust the used counter - its an atomic counter and whatever we see
 136     // must have been the truth once - and from that we reconstruct a likely set of committed/reserved
 137     // values.
 138     metaspace::InternalStats::inc_num_inconsistent_stats();
 139     if (c < u) {
 140       c = align_up(u, Metaspace::commit_alignment());
 141     }
 142     if (r < c) {
 143       r = align_up(c, Metaspace::reserve_alignment());
 144     }
 145   }
 146   return MetaspaceStats(r, c, u);
 147 }
 148 
 149 MetaspaceCombinedStats MetaspaceUtils::get_combined_statistics() {
 150   return MetaspaceCombinedStats(get_statistics(Metaspace::ClassType), get_statistics(Metaspace::NonClassType));
 151 }
 152 
 153 void MetaspaceUtils::print_metaspace_change(const MetaspaceCombinedStats& pre_meta_values) {
 154   // Get values now:
 155   const MetaspaceCombinedStats meta_values = get_combined_statistics();
 156 
 157   // We print used and committed since these are the most useful at-a-glance vitals for Metaspace:
 158   // - used tells you how much memory is actually used for metadata
 159   // - committed tells you how much memory is committed for the purpose of metadata
 160   // The difference between those two would be waste, which can have various forms (freelists,
 161   //   unused parts of committed chunks etc)
 162   //
 163   // Left out is reserved, since this is not as exciting as the first two values: for class space,
 164   // it is a constant (to uninformed users, often confusingly large). For non-class space, it would
 165   // be interesting since free chunks can be uncommitted, but for now it is left out.
 166 
 167   if (Metaspace::using_class_space()) {
 168     log_info(gc, metaspace)(HEAP_CHANGE_FORMAT" "
 169                             HEAP_CHANGE_FORMAT" "
 170                             HEAP_CHANGE_FORMAT,
 171                             HEAP_CHANGE_FORMAT_ARGS("Metaspace",
 172                                                     pre_meta_values.used(),
 173                                                     pre_meta_values.committed(),
 174                                                     meta_values.used(),
 175                                                     meta_values.committed()),
 176                             HEAP_CHANGE_FORMAT_ARGS("NonClass",
 177                                                     pre_meta_values.non_class_used(),
 178                                                     pre_meta_values.non_class_committed(),
 179                                                     meta_values.non_class_used(),
 180                                                     meta_values.non_class_committed()),
 181                             HEAP_CHANGE_FORMAT_ARGS("Class",
 182                                                     pre_meta_values.class_used(),
 183                                                     pre_meta_values.class_committed(),
 184                                                     meta_values.class_used(),
 185                                                     meta_values.class_committed()));
 186   } else {
 187     log_info(gc, metaspace)(HEAP_CHANGE_FORMAT,
 188                             HEAP_CHANGE_FORMAT_ARGS("Metaspace",
 189                                                     pre_meta_values.used(),
 190                                                     pre_meta_values.committed(),
 191                                                     meta_values.used(),
 192                                                     meta_values.committed()));
 193   }
 194 }
 195 
 196 // This will print out a basic metaspace usage report but
 197 // unlike print_report() is guaranteed not to lock or to walk the CLDG.
 198 void MetaspaceUtils::print_basic_report(outputStream* out, size_t scale) {
 199   MetaspaceReporter::print_basic_report(out, scale);
 200 }
 201 
 202 // Prints a report about the current metaspace state.
 203 // Optional parts can be enabled via flags.
 204 // Function will walk the CLDG and will lock the expand lock; if that is not
 205 // convenient, use print_basic_report() instead.
 206 void MetaspaceUtils::print_report(outputStream* out, size_t scale) {
 207   const int flags =
 208       (int)MetaspaceReporter::Option::ShowLoaders |
 209       (int)MetaspaceReporter::Option::BreakDownByChunkType |
 210       (int)MetaspaceReporter::Option::ShowClasses;
 211   MetaspaceReporter::print_report(out, scale, flags);
 212 }
 213 
 214 void MetaspaceUtils::print_on(outputStream* out) {
 215 
 216   // Used from all GCs. It first prints out totals, then, separately, the class space portion.
 217   MetaspaceCombinedStats stats = get_combined_statistics();
 218   out->print_cr(" Metaspace       "
 219                 "used "      SIZE_FORMAT "K, "
 220                 "committed " SIZE_FORMAT "K, "
 221                 "reserved "  SIZE_FORMAT "K",
 222                 stats.used()/K,
 223                 stats.committed()/K,
 224                 stats.reserved()/K);
 225 
 226   if (Metaspace::using_class_space()) {
 227     out->print_cr("  class space    "
 228                   "used "      SIZE_FORMAT "K, "
 229                   "committed " SIZE_FORMAT "K, "
 230                   "reserved "  SIZE_FORMAT "K",
 231                   stats.class_space_stats().used()/K,
 232                   stats.class_space_stats().committed()/K,
 233                   stats.class_space_stats().reserved()/K);
 234   }
 235 }
 236 
 237 #ifdef ASSERT
 238 void MetaspaceUtils::verify() {
 239   if (Metaspace::initialized()) {
 240 
 241     // Verify non-class chunkmanager...
 242     ChunkManager* cm = ChunkManager::chunkmanager_nonclass();
 243     cm->verify();
 244 
 245     // ... and space list.
 246     VirtualSpaceList* vsl = VirtualSpaceList::vslist_nonclass();
 247     vsl->verify();
 248 
 249     if (Metaspace::using_class_space()) {
 250       // If we use compressed class pointers, verify class chunkmanager...
 251       cm = ChunkManager::chunkmanager_class();
 252       cm->verify();
 253 
 254       // ... and class spacelist.
 255       vsl = VirtualSpaceList::vslist_class();
 256       vsl->verify();
 257     }
 258 
 259   }
 260 }
 261 #endif
 262 
 263 ////////////////////////////////7
 264 // MetaspaceGC methods
 265 
 266 volatile size_t MetaspaceGC::_capacity_until_GC = 0;
 267 uint MetaspaceGC::_shrink_factor = 0;
 268 
 269 // VM_CollectForMetadataAllocation is the vm operation used to GC.
 270 // Within the VM operation after the GC the attempt to allocate the metadata
 271 // should succeed.  If the GC did not free enough space for the metaspace
 272 // allocation, the HWM is increased so that another virtualspace will be
 273 // allocated for the metadata.  With perm gen the increase in the perm
 274 // gen had bounds, MinMetaspaceExpansion and MaxMetaspaceExpansion.  The
 275 // metaspace policy uses those as the small and large steps for the HWM.
 276 //
 277 // After the GC the compute_new_size() for MetaspaceGC is called to
 278 // resize the capacity of the metaspaces.  The current implementation
 279 // is based on the flags MinMetaspaceFreeRatio and MaxMetaspaceFreeRatio used
 280 // to resize the Java heap by some GC's.  New flags can be implemented
 281 // if really needed.  MinMetaspaceFreeRatio is used to calculate how much
 282 // free space is desirable in the metaspace capacity to decide how much
 283 // to increase the HWM.  MaxMetaspaceFreeRatio is used to decide how much
 284 // free space is desirable in the metaspace capacity before decreasing
 285 // the HWM.
 286 
 287 // Calculate the amount to increase the high water mark (HWM).
 288 // Increase by a minimum amount (MinMetaspaceExpansion) so that
 289 // another expansion is not requested too soon.  If that is not
 290 // enough to satisfy the allocation, increase by MaxMetaspaceExpansion.
 291 // If that is still not enough, expand by the size of the allocation
 292 // plus some.
 293 size_t MetaspaceGC::delta_capacity_until_GC(size_t bytes) {
 294   size_t min_delta = MinMetaspaceExpansion;
 295   size_t max_delta = MaxMetaspaceExpansion;
 296   size_t delta = align_up(bytes, Metaspace::commit_alignment());
 297 
 298   if (delta <= min_delta) {
 299     delta = min_delta;
 300   } else if (delta <= max_delta) {
 301     // Don't want to hit the high water mark on the next
 302     // allocation so make the delta greater than just enough
 303     // for this allocation.
 304     delta = max_delta;
 305   } else {
 306     // This allocation is large but the next ones are probably not
 307     // so increase by the minimum.
 308     delta = delta + min_delta;
 309   }
 310 
 311   assert_is_aligned(delta, Metaspace::commit_alignment());
 312 
 313   return delta;
 314 }
 315 
 316 size_t MetaspaceGC::capacity_until_GC() {
 317   size_t value = Atomic::load_acquire(&_capacity_until_GC);
 318   assert(value >= MetaspaceSize, "Not initialized properly?");
 319   return value;
 320 }
 321 
 322 // Try to increase the _capacity_until_GC limit counter by v bytes.
 323 // Returns true if it succeeded. It may fail if either another thread
 324 // concurrently increased the limit or the new limit would be larger
 325 // than MaxMetaspaceSize.
 326 // On success, optionally returns new and old metaspace capacity in
 327 // new_cap_until_GC and old_cap_until_GC respectively.
 328 // On error, optionally sets can_retry to indicate whether if there is
 329 // actually enough space remaining to satisfy the request.
 330 bool MetaspaceGC::inc_capacity_until_GC(size_t v, size_t* new_cap_until_GC, size_t* old_cap_until_GC, bool* can_retry) {
 331   assert_is_aligned(v, Metaspace::commit_alignment());
 332 
 333   size_t old_capacity_until_GC = _capacity_until_GC;
 334   size_t new_value = old_capacity_until_GC + v;
 335 
 336   if (new_value < old_capacity_until_GC) {
 337     // The addition wrapped around, set new_value to aligned max value.
 338     new_value = align_down(max_uintx, Metaspace::reserve_alignment());
 339   }
 340 
 341   if (new_value > MaxMetaspaceSize) {
 342     if (can_retry != nullptr) {
 343       *can_retry = false;
 344     }
 345     return false;
 346   }
 347 
 348   if (can_retry != nullptr) {
 349     *can_retry = true;
 350   }
 351   size_t prev_value = Atomic::cmpxchg(&_capacity_until_GC, old_capacity_until_GC, new_value);
 352 
 353   if (old_capacity_until_GC != prev_value) {
 354     return false;
 355   }
 356 
 357   if (new_cap_until_GC != nullptr) {
 358     *new_cap_until_GC = new_value;
 359   }
 360   if (old_cap_until_GC != nullptr) {
 361     *old_cap_until_GC = old_capacity_until_GC;
 362   }
 363   return true;
 364 }
 365 
 366 size_t MetaspaceGC::dec_capacity_until_GC(size_t v) {
 367   assert_is_aligned(v, Metaspace::commit_alignment());
 368 
 369   return Atomic::sub(&_capacity_until_GC, v);
 370 }
 371 
 372 void MetaspaceGC::initialize() {
 373   // Set the high-water mark to MaxMetapaceSize during VM initializaton since
 374   // we can't do a GC during initialization.
 375   _capacity_until_GC = MaxMetaspaceSize;
 376 }
 377 
 378 void MetaspaceGC::post_initialize() {
 379   // Reset the high-water mark once the VM initialization is done.
 380   _capacity_until_GC = MAX2(MetaspaceUtils::committed_bytes(), MetaspaceSize);
 381 }
 382 
 383 bool MetaspaceGC::can_expand(size_t word_size, bool is_class) {
 384   // Check if the compressed class space is full.
 385   if (is_class && Metaspace::using_class_space()) {
 386     size_t class_committed = MetaspaceUtils::committed_bytes(Metaspace::ClassType);
 387     if (class_committed + word_size * BytesPerWord > CompressedClassSpaceSize) {
 388       log_trace(gc, metaspace, freelist)("Cannot expand %s metaspace by " SIZE_FORMAT " words (CompressedClassSpaceSize = " SIZE_FORMAT " words)",
 389                 (is_class ? "class" : "non-class"), word_size, CompressedClassSpaceSize / sizeof(MetaWord));
 390       return false;
 391     }
 392   }
 393 
 394   // Check if the user has imposed a limit on the metaspace memory.
 395   size_t committed_bytes = MetaspaceUtils::committed_bytes();
 396   if (committed_bytes + word_size * BytesPerWord > MaxMetaspaceSize) {
 397     log_trace(gc, metaspace, freelist)("Cannot expand %s metaspace by " SIZE_FORMAT " words (MaxMetaspaceSize = " SIZE_FORMAT " words)",
 398               (is_class ? "class" : "non-class"), word_size, MaxMetaspaceSize / sizeof(MetaWord));
 399     return false;
 400   }
 401 
 402   return true;
 403 }
 404 
 405 size_t MetaspaceGC::allowed_expansion() {
 406   size_t committed_bytes = MetaspaceUtils::committed_bytes();
 407   size_t capacity_until_gc = capacity_until_GC();
 408 
 409   size_t left_until_max  = MaxMetaspaceSize - committed_bytes;
 410   // capacity_until_GC may have been decreased concurrently and may
 411   // temporarily be lower than what metaspace has committed. Allow for that.
 412   size_t left_until_GC = capacity_until_gc > committed_bytes ?
 413       capacity_until_gc - committed_bytes : 0;
 414   size_t left_to_commit = MIN2(left_until_GC, left_until_max);
 415   log_trace(gc, metaspace, freelist)("allowed expansion words: " SIZE_FORMAT
 416             " (left_until_max: " SIZE_FORMAT ", left_until_GC: " SIZE_FORMAT ".",
 417             left_to_commit / BytesPerWord, left_until_max / BytesPerWord, left_until_GC / BytesPerWord);
 418 
 419   return left_to_commit / BytesPerWord;
 420 }
 421 
 422 void MetaspaceGC::compute_new_size() {
 423   assert(_shrink_factor <= 100, "invalid shrink factor");
 424   uint current_shrink_factor = _shrink_factor;
 425   _shrink_factor = 0;
 426 
 427   // Using committed_bytes() for used_after_gc is an overestimation, since the
 428   // chunk free lists are included in committed_bytes() and the memory in an
 429   // un-fragmented chunk free list is available for future allocations.
 430   // However, if the chunk free lists becomes fragmented, then the memory may
 431   // not be available for future allocations and the memory is therefore "in use".
 432   // Including the chunk free lists in the definition of "in use" is therefore
 433   // necessary. Not including the chunk free lists can cause capacity_until_GC to
 434   // shrink below committed_bytes() and this has caused serious bugs in the past.
 435   const double used_after_gc = (double)MetaspaceUtils::committed_bytes();
 436   const size_t capacity_until_GC = MetaspaceGC::capacity_until_GC();
 437 
 438   const double minimum_free_percentage = MinMetaspaceFreeRatio / 100.0;
 439   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
 440 
 441   const double min_tmp = used_after_gc / maximum_used_percentage;
 442   size_t minimum_desired_capacity =
 443     (size_t)MIN2(min_tmp, double(MaxMetaspaceSize));
 444   // Don't shrink less than the initial generation size
 445   minimum_desired_capacity = MAX2(minimum_desired_capacity,
 446                                   MetaspaceSize);
 447 
 448   log_trace(gc, metaspace)("MetaspaceGC::compute_new_size: ");
 449   log_trace(gc, metaspace)("    minimum_free_percentage: %6.2f  maximum_used_percentage: %6.2f",
 450                            minimum_free_percentage, maximum_used_percentage);
 451   log_trace(gc, metaspace)("     used_after_gc       : %6.1fKB", used_after_gc / (double) K);
 452 
 453   size_t shrink_bytes = 0;
 454   if (capacity_until_GC < minimum_desired_capacity) {
 455     // If we have less capacity below the metaspace HWM, then
 456     // increment the HWM.
 457     size_t expand_bytes = minimum_desired_capacity - capacity_until_GC;
 458     expand_bytes = align_up(expand_bytes, Metaspace::commit_alignment());
 459     // Don't expand unless it's significant
 460     if (expand_bytes >= MinMetaspaceExpansion) {
 461       size_t new_capacity_until_GC = 0;
 462       bool succeeded = MetaspaceGC::inc_capacity_until_GC(expand_bytes, &new_capacity_until_GC);
 463       assert(succeeded, "Should always successfully increment HWM when at safepoint");
 464 
 465       Metaspace::tracer()->report_gc_threshold(capacity_until_GC,
 466                                                new_capacity_until_GC,
 467                                                MetaspaceGCThresholdUpdater::ComputeNewSize);
 468       log_trace(gc, metaspace)("    expanding:  minimum_desired_capacity: %6.1fKB  expand_bytes: %6.1fKB  MinMetaspaceExpansion: %6.1fKB  new metaspace HWM:  %6.1fKB",
 469                                (double) minimum_desired_capacity / (double) K,
 470                                (double) expand_bytes / (double) K,
 471                                (double) MinMetaspaceExpansion / (double) K,
 472                                (double) new_capacity_until_GC / (double) K);
 473     }
 474     return;
 475   }
 476 
 477   // No expansion, now see if we want to shrink
 478   // We would never want to shrink more than this
 479   assert(capacity_until_GC >= minimum_desired_capacity,
 480          SIZE_FORMAT " >= " SIZE_FORMAT,
 481          capacity_until_GC, minimum_desired_capacity);
 482   size_t max_shrink_bytes = capacity_until_GC - minimum_desired_capacity;
 483 
 484   // Should shrinking be considered?
 485   if (MaxMetaspaceFreeRatio < 100) {
 486     const double maximum_free_percentage = MaxMetaspaceFreeRatio / 100.0;
 487     const double minimum_used_percentage = 1.0 - maximum_free_percentage;
 488     const double max_tmp = used_after_gc / minimum_used_percentage;
 489     size_t maximum_desired_capacity = (size_t)MIN2(max_tmp, double(MaxMetaspaceSize));
 490     maximum_desired_capacity = MAX2(maximum_desired_capacity,
 491                                     MetaspaceSize);
 492     log_trace(gc, metaspace)("    maximum_free_percentage: %6.2f  minimum_used_percentage: %6.2f",
 493                              maximum_free_percentage, minimum_used_percentage);
 494     log_trace(gc, metaspace)("    minimum_desired_capacity: %6.1fKB  maximum_desired_capacity: %6.1fKB",
 495                              (double) minimum_desired_capacity / (double) K, (double) maximum_desired_capacity / (double) K);
 496 
 497     assert(minimum_desired_capacity <= maximum_desired_capacity,
 498            "sanity check");
 499 
 500     if (capacity_until_GC > maximum_desired_capacity) {
 501       // Capacity too large, compute shrinking size
 502       shrink_bytes = capacity_until_GC - maximum_desired_capacity;
 503       // We don't want shrink all the way back to initSize if people call
 504       // System.gc(), because some programs do that between "phases" and then
 505       // we'd just have to grow the heap up again for the next phase.  So we
 506       // damp the shrinking: 0% on the first call, 10% on the second call, 40%
 507       // on the third call, and 100% by the fourth call.  But if we recompute
 508       // size without shrinking, it goes back to 0%.
 509       shrink_bytes = shrink_bytes / 100 * current_shrink_factor;
 510 
 511       shrink_bytes = align_down(shrink_bytes, Metaspace::commit_alignment());
 512 
 513       assert(shrink_bytes <= max_shrink_bytes,
 514              "invalid shrink size " SIZE_FORMAT " not <= " SIZE_FORMAT,
 515              shrink_bytes, max_shrink_bytes);
 516       if (current_shrink_factor == 0) {
 517         _shrink_factor = 10;
 518       } else {
 519         _shrink_factor = MIN2(current_shrink_factor * 4, (uint) 100);
 520       }
 521       log_trace(gc, metaspace)("    shrinking:  initThreshold: %.1fK  maximum_desired_capacity: %.1fK",
 522                                (double) MetaspaceSize / (double) K, (double) maximum_desired_capacity / (double) K);
 523       log_trace(gc, metaspace)("    shrink_bytes: %.1fK  current_shrink_factor: %d  new shrink factor: %d  MinMetaspaceExpansion: %.1fK",
 524                                (double) shrink_bytes / (double) K, current_shrink_factor, _shrink_factor, (double) MinMetaspaceExpansion / (double) K);
 525     }
 526   }
 527 
 528   // Don't shrink unless it's significant
 529   if (shrink_bytes >= MinMetaspaceExpansion &&
 530       ((capacity_until_GC - shrink_bytes) >= MetaspaceSize)) {
 531     size_t new_capacity_until_GC = MetaspaceGC::dec_capacity_until_GC(shrink_bytes);
 532     Metaspace::tracer()->report_gc_threshold(capacity_until_GC,
 533                                              new_capacity_until_GC,
 534                                              MetaspaceGCThresholdUpdater::ComputeNewSize);
 535   }
 536 }
 537 
 538 //////  Metaspace methods /////
 539 
 540 const MetaspaceTracer* Metaspace::_tracer = nullptr;
 541 const void* Metaspace::_class_space_start = nullptr;
 542 const void* Metaspace::_class_space_end = nullptr;
 543 
 544 bool Metaspace::initialized() {
 545   return metaspace::MetaspaceContext::context_nonclass() != nullptr
 546       LP64_ONLY(&& (using_class_space() ? Metaspace::class_space_is_initialized() : true));
 547 }
 548 
 549 #ifdef _LP64
 550 
 551 void Metaspace::print_compressed_class_space(outputStream* st) {
 552   if (VirtualSpaceList::vslist_class() != nullptr) {
 553     MetaWord* base = VirtualSpaceList::vslist_class()->base_of_first_node();
 554     size_t size = VirtualSpaceList::vslist_class()->word_size_of_first_node();
 555     MetaWord* top = base + size;
 556     st->print("Compressed class space mapped at: " PTR_FORMAT "-" PTR_FORMAT ", reserved size: " SIZE_FORMAT,
 557                p2i(base), p2i(top), (top - base) * BytesPerWord);
 558     st->cr();
 559   }
 560 }
 561 
 562 // Given a prereserved space, use that to set up the compressed class space list.
 563 void Metaspace::initialize_class_space(ReservedSpace rs) {
 564   assert(rs.size() >= CompressedClassSpaceSize,
 565          SIZE_FORMAT " != " SIZE_FORMAT, rs.size(), CompressedClassSpaceSize);
 566   assert(using_class_space(), "Must be using class space");
 567 
 568   assert(rs.size() == CompressedClassSpaceSize, SIZE_FORMAT " != " SIZE_FORMAT,
 569          rs.size(), CompressedClassSpaceSize);
 570   assert(is_aligned(rs.base(), Metaspace::reserve_alignment()) &&
 571          is_aligned(rs.size(), Metaspace::reserve_alignment()),
 572          "wrong alignment");
 573 
 574   MetaspaceContext::initialize_class_space_context(rs);
 575   _class_space_start = rs.base();
 576   _class_space_end = rs.end();
 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() != nullptr;
 582 }
 583 
 584 // Reserve a range of memory that is to contain narrow Klass IDs. If "try_in_low_address_ranges"
 585 // is true, we will attempt to reserve memory suitable for zero-based encoding.
 586 ReservedSpace Metaspace::reserve_address_space_for_compressed_classes(size_t size, bool optimize_for_zero_base) {
 587   char* result = nullptr;
 588 
 589   NOT_ZERO(result =
 590       (char*) CompressedKlassPointers::reserve_address_space_for_compressed_classes(size, RandomizeClassSpaceLocation,
 591                                                                                     optimize_for_zero_base));
 592 
 593   if (result == nullptr) {
 594     // Fallback: reserve anywhere
 595     log_debug(metaspace, map)("Trying anywhere...");
 596     result = os::reserve_memory_aligned(size, Metaspace::reserve_alignment(), false);
 597   }
 598 
 599   // Wrap resulting range in ReservedSpace
 600   ReservedSpace rs;
 601   if (result != nullptr) {
 602     log_debug(metaspace, map)("Mapped at " PTR_FORMAT, p2i(result));
 603     assert(is_aligned(result, Metaspace::reserve_alignment()), "Alignment too small for metaspace");
 604     rs = ReservedSpace::space_for_range(result, size, Metaspace::reserve_alignment(),
 605                                                       os::vm_page_size(), false, false);
 606   } else {
 607     log_debug(metaspace, map)("Failed to map.");
 608     rs = ReservedSpace();
 609   }
 610   return rs;
 611 }
 612 #endif // _LP64
 613 
 614 size_t Metaspace::reserve_alignment_words() {
 615   return metaspace::Settings::virtual_space_node_reserve_alignment_words();
 616 }
 617 
 618 size_t Metaspace::commit_alignment_words() {
 619   return metaspace::Settings::commit_granule_words();
 620 }
 621 
 622 void Metaspace::ergo_initialize() {
 623 
 624   // Must happen before using any setting from Settings::---
 625   metaspace::Settings::ergo_initialize();
 626 
 627   // MaxMetaspaceSize and CompressedClassSpaceSize:
 628   //
 629   // MaxMetaspaceSize is the maximum size, in bytes, of memory we are allowed
 630   //  to commit for the Metaspace.
 631   //  It is just a number; a limit we compare against before committing. It
 632   //  does not have to be aligned to anything.
 633   //  It gets used as compare value before attempting to increase the metaspace
 634   //  commit charge. It defaults to max_uintx (unlimited).
 635   //
 636   // CompressedClassSpaceSize is the size, in bytes, of the address range we
 637   //  pre-reserve for the compressed class space (if we use class space).
 638   //  This size has to be aligned to the metaspace reserve alignment (to the
 639   //  size of a root chunk). It gets aligned up from whatever value the caller
 640   //  gave us to the next multiple of root chunk size.
 641   //
 642   // Note: Strictly speaking MaxMetaspaceSize and CompressedClassSpaceSize have
 643   //  very little to do with each other. The notion often encountered:
 644   //  MaxMetaspaceSize = CompressedClassSpaceSize + <non-class metadata size>
 645   //  is subtly wrong: MaxMetaspaceSize can besmaller than CompressedClassSpaceSize,
 646   //  in which case we just would not be able to fully commit the class space range.
 647   //
 648   // We still adjust CompressedClassSpaceSize to reasonable limits, mainly to
 649   //  save on reserved space, and to make ergnonomics less confusing.
 650 
 651   MaxMetaspaceSize = MAX2(MaxMetaspaceSize, commit_alignment());
 652 
 653   if (UseCompressedClassPointers) {
 654     // Let CCS size not be larger than 80% of MaxMetaspaceSize. Note that is
 655     // grossly over-dimensioned for most usage scenarios; typical ratio of
 656     // class space : non class space usage is about 1:6. With many small classes,
 657     // it can get as low as 1:2. It is not a big deal though since ccs is only
 658     // reserved and will be committed on demand only.
 659     size_t max_ccs_size = 8 * (MaxMetaspaceSize / 10);
 660     size_t adjusted_ccs_size = MIN2(CompressedClassSpaceSize, max_ccs_size);
 661 
 662     // CCS must be aligned to root chunk size, and be at least the size of one
 663     //  root chunk.
 664     adjusted_ccs_size = align_up(adjusted_ccs_size, reserve_alignment());
 665     adjusted_ccs_size = MAX2(adjusted_ccs_size, reserve_alignment());
 666 
 667     // Note: re-adjusting may have us left with a CompressedClassSpaceSize
 668     //  larger than MaxMetaspaceSize for very small values of MaxMetaspaceSize.
 669     //  Lets just live with that, its not a big deal.
 670 
 671     if (adjusted_ccs_size != CompressedClassSpaceSize) {
 672       FLAG_SET_ERGO(CompressedClassSpaceSize, adjusted_ccs_size);
 673       log_info(metaspace)("Setting CompressedClassSpaceSize to " SIZE_FORMAT ".",
 674                           CompressedClassSpaceSize);
 675     }
 676   }
 677 
 678   // Set MetaspaceSize, MinMetaspaceExpansion and MaxMetaspaceExpansion
 679   if (MetaspaceSize > MaxMetaspaceSize) {
 680     MetaspaceSize = MaxMetaspaceSize;
 681   }
 682 
 683   MetaspaceSize = align_down_bounded(MetaspaceSize, commit_alignment());
 684 
 685   assert(MetaspaceSize <= MaxMetaspaceSize, "MetaspaceSize should be limited by MaxMetaspaceSize");
 686 
 687   MinMetaspaceExpansion = align_down_bounded(MinMetaspaceExpansion, commit_alignment());
 688   MaxMetaspaceExpansion = align_down_bounded(MaxMetaspaceExpansion, commit_alignment());
 689 
 690 }
 691 
 692 void Metaspace::global_initialize() {
 693   MetaspaceGC::initialize(); // <- since we do not prealloc init chunks anymore is this still needed?
 694 
 695   metaspace::ChunkHeaderPool::initialize();
 696 
 697   if (CDSConfig::is_dumping_static_archive()) {
 698     assert(!UseSharedSpaces, "sanity");
 699     MetaspaceShared::initialize_for_static_dump();
 700   }
 701 
 702   // If UseCompressedClassPointers=1, we have two cases:
 703   // a) if CDS is active (runtime, Xshare=on), it will create the class space
 704   //    for us, initialize it and set up CompressedKlassPointers encoding.
 705   //    Class space will be reserved above the mapped archives.
 706   // b) if CDS either deactivated (Xshare=off) or a static dump is to be done (Xshare:dump),
 707   //    we will create the class space on our own. It will be placed above the java heap,
 708   //    since we assume it has been placed in low
 709   //    address regions. We may rethink this (see JDK-8244943). Failing that,
 710   //    it will be placed anywhere.
 711 
 712 #if INCLUDE_CDS
 713   // case (a)
 714   if (UseSharedSpaces) {
 715     if (!FLAG_IS_DEFAULT(CompressedClassSpaceBaseAddress)) {
 716       log_warning(metaspace)("CDS active - ignoring CompressedClassSpaceBaseAddress.");
 717     }
 718     MetaspaceShared::initialize_runtime_shared_and_meta_spaces();
 719     // If any of the archived space fails to map, UseSharedSpaces
 720     // is reset to false.
 721   }
 722 #endif // INCLUDE_CDS
 723 
 724 #ifdef _LP64
 725 
 726   if (using_class_space() && !class_space_is_initialized()) {
 727     assert(!UseSharedSpaces, "CDS archive is not mapped at this point");
 728 
 729     // case (b) (No CDS)
 730     ReservedSpace rs;
 731     const size_t size = align_up(CompressedClassSpaceSize, Metaspace::reserve_alignment());
 732 
 733     // If CompressedClassSpaceBaseAddress is set, we attempt to force-map class space to
 734     // the given address. This is a debug-only feature aiding tests. Due to the ASLR lottery
 735     // this may fail, in which case the VM will exit after printing an appropriate message.
 736     // Tests using this switch should cope with that.
 737     if (CompressedClassSpaceBaseAddress != 0) {
 738       const address base = (address)CompressedClassSpaceBaseAddress;
 739       if (!is_aligned(base, Metaspace::reserve_alignment())) {
 740         vm_exit_during_initialization(
 741             err_msg("CompressedClassSpaceBaseAddress=" PTR_FORMAT " invalid "
 742                     "(must be aligned to " SIZE_FORMAT_X ").",
 743                     CompressedClassSpaceBaseAddress, Metaspace::reserve_alignment()));
 744       }
 745       rs = ReservedSpace(size, Metaspace::reserve_alignment(),
 746                          os::vm_page_size() /* large */, (char*)base);
 747       if (rs.is_reserved()) {
 748         log_info(metaspace)("Successfully forced class space address to " PTR_FORMAT, p2i(base));
 749       } else {
 750         LogTarget(Debug, metaspace) lt;
 751         if (lt.is_enabled()) {
 752           LogStream ls(lt);
 753           os::print_memory_mappings((char*)base, size, &ls);
 754         }
 755         vm_exit_during_initialization(
 756             err_msg("CompressedClassSpaceBaseAddress=" PTR_FORMAT " given, but reserving class space failed.",
 757                 CompressedClassSpaceBaseAddress));
 758       }
 759     }
 760 
 761     // ...failing that, reserve anywhere, but let platform do optimized placement:
 762     if (!rs.is_reserved()) {
 763       log_info(metaspace)("Reserving compressed class space anywhere");
 764       rs = Metaspace::reserve_address_space_for_compressed_classes(size, true);
 765     }
 766 
 767     // ...failing that, give up.
 768     if (!rs.is_reserved()) {
 769       vm_exit_during_initialization(
 770           err_msg("Could not allocate compressed class space: " SIZE_FORMAT " bytes",
 771                    CompressedClassSpaceSize));
 772     }
 773 
 774     // Mark class space as such
 775     MemTracker::record_virtual_memory_type((address)rs.base(), mtClass);
 776 
 777     // Initialize space
 778     Metaspace::initialize_class_space(rs);
 779 
 780     // Set up compressed class pointer encoding.
 781     // In CDS=off mode, we give the JVM some leeway to choose a favorable base/shift combination.
 782     CompressedKlassPointers::initialize((address)rs.base(), rs.size());
 783   }
 784 
 785 #endif
 786 
 787   // Initialize non-class virtual space list, and its chunk manager:
 788   MetaspaceContext::initialize_nonclass_space_context();
 789 
 790   _tracer = new MetaspaceTracer();
 791 
 792   // We must prevent the very first address of the ccs from being used to store
 793   // metadata, since that address would translate to a narrow pointer of 0, and the
 794   // VM does not distinguish between "narrow 0 as in null" and "narrow 0 as in start
 795   //  of ccs".
 796   // Before Elastic Metaspace that did not happen due to the fact that every Metachunk
 797   // had a header and therefore could not allocate anything at offset 0.
 798 #ifdef _LP64
 799   if (using_class_space()) {
 800     // The simplest way to fix this is to allocate a tiny dummy chunk right at the
 801     // start of ccs and do not use it for anything.
 802     MetaspaceContext::context_class()->cm()->get_chunk(metaspace::chunklevel::HIGHEST_CHUNK_LEVEL);
 803   }
 804 #endif
 805 
 806 #ifdef _LP64
 807   if (UseCompressedClassPointers) {
 808     // Note: "cds" would be a better fit but keep this for backward compatibility.
 809     LogTarget(Info, gc, metaspace) lt;
 810     if (lt.is_enabled()) {
 811       ResourceMark rm;
 812       LogStream ls(lt);
 813       CDS_ONLY(MetaspaceShared::print_on(&ls);)
 814       Metaspace::print_compressed_class_space(&ls);
 815       CompressedKlassPointers::print_mode(&ls);
 816     }
 817   }
 818 #endif
 819 
 820 }
 821 
 822 void Metaspace::post_initialize() {
 823   MetaspaceGC::post_initialize();
 824 }
 825 
 826 size_t Metaspace::max_allocation_word_size() {
 827   return metaspace::chunklevel::MAX_CHUNK_WORD_SIZE;
 828 }
 829 
 830 // This version of Metaspace::allocate does not throw OOM but simply returns null, and
 831 // is suitable for calling from non-Java threads.
 832 // Callers are responsible for checking null.
 833 MetaWord* Metaspace::allocate(ClassLoaderData* loader_data, size_t word_size,
 834                               MetaspaceObj::Type type) {
 835   assert(word_size <= Metaspace::max_allocation_word_size(),
 836          "allocation size too large (" SIZE_FORMAT ")", word_size);
 837 
 838   assert(loader_data != nullptr, "Should never pass around a null loader_data. "
 839         "ClassLoaderData::the_null_class_loader_data() should have been used.");
 840 
 841   // Deal with concurrent unloading failed allocation starvation
 842   MetaspaceCriticalAllocation::block_if_concurrent_purge();
 843 
 844   MetadataType mdtype = (type == MetaspaceObj::ClassType) ? ClassType : NonClassType;
 845 
 846   // Try to allocate metadata.
 847   MetaWord* result = loader_data->metaspace_non_null()->allocate(word_size, mdtype);
 848 
 849   if (result != nullptr) {
 850 #ifdef ASSERT
 851     if (using_class_space() && mdtype == ClassType) {
 852       assert(is_in_class_space(result) &&
 853              is_aligned(result, CompressedKlassPointers::klass_alignment_in_bytes()), "Sanity");
 854     } else {
 855       assert((is_in_class_space(result) || is_in_nonclass_metaspace(result)) &&
 856              is_aligned(result, Metaspace::min_allocation_alignment_bytes), "Sanity");
 857     }
 858 #endif
 859     // Zero initialize.
 860     Copy::fill_to_words((HeapWord*)result, word_size, 0);

 861     log_trace(metaspace)("Metaspace::allocate: type %d return " PTR_FORMAT ".", (int)type, p2i(result));
 862   }
 863 
 864   return result;
 865 }
 866 
 867 MetaWord* Metaspace::allocate(ClassLoaderData* loader_data, size_t word_size,
 868                               MetaspaceObj::Type type, TRAPS) {
 869 
 870   if (HAS_PENDING_EXCEPTION) {
 871     assert(false, "Should not allocate with exception pending");
 872     return nullptr;  // caller does a CHECK_NULL too
 873   }
 874   assert(!THREAD->owns_locks(), "allocating metaspace while holding mutex");
 875 
 876   MetaWord* result = allocate(loader_data, word_size, type);
 877 
 878   if (result == nullptr) {
 879     MetadataType mdtype = (type == MetaspaceObj::ClassType) ? ClassType : NonClassType;
 880     tracer()->report_metaspace_allocation_failure(loader_data, word_size, type, mdtype);
 881 
 882     // Allocation failed.
 883     if (is_init_completed()) {
 884       // Only start a GC if the bootstrapping has completed.
 885       // Try to clean out some heap memory and retry. This can prevent premature
 886       // expansion of the metaspace.
 887       result = Universe::heap()->satisfy_failed_metadata_allocation(loader_data, word_size, mdtype);
 888     }
 889 
 890     if (result == nullptr) {
 891       report_metadata_oome(loader_data, word_size, type, mdtype, THREAD);
 892       assert(HAS_PENDING_EXCEPTION, "sanity");
 893       return nullptr;
 894     }
 895 
 896     // Zero initialize.
 897     Copy::fill_to_words((HeapWord*)result, word_size, 0);
 898 
 899     log_trace(metaspace)("Metaspace::allocate: type %d return " PTR_FORMAT ".", (int)type, p2i(result));
 900   }
 901 
 902   return result;
 903 }
 904 
 905 void Metaspace::report_metadata_oome(ClassLoaderData* loader_data, size_t word_size, MetaspaceObj::Type type, MetadataType mdtype, TRAPS) {
 906   tracer()->report_metadata_oom(loader_data, word_size, type, mdtype);
 907 
 908   // If result is still null, we are out of memory.
 909   Log(gc, metaspace, freelist, oom) log;
 910   if (log.is_info()) {
 911     log.info("Metaspace (%s) allocation failed for size " SIZE_FORMAT,
 912              is_class_space_allocation(mdtype) ? "class" : "data", word_size);
 913     ResourceMark rm;
 914     if (log.is_debug()) {
 915       if (loader_data->metaspace_or_null() != nullptr) {
 916         LogStream ls(log.debug());
 917         loader_data->print_value_on(&ls);
 918       }
 919     }
 920     LogStream ls(log.info());
 921     // In case of an OOM, log out a short but still useful report.
 922     MetaspaceUtils::print_basic_report(&ls, 0);
 923   }
 924 
 925   bool out_of_compressed_class_space = false;
 926   if (is_class_space_allocation(mdtype)) {
 927     ClassLoaderMetaspace* metaspace = loader_data->metaspace_non_null();
 928     out_of_compressed_class_space =
 929       MetaspaceUtils::committed_bytes(Metaspace::ClassType) +
 930       align_up(word_size * BytesPerWord, 4 * M) >
 931       CompressedClassSpaceSize;
 932   }
 933 
 934   // -XX:+HeapDumpOnOutOfMemoryError and -XX:OnOutOfMemoryError support
 935   const char* space_string = out_of_compressed_class_space ?
 936     "Compressed class space" : "Metaspace";
 937 
 938   report_java_out_of_memory(space_string);
 939 
 940   if (JvmtiExport::should_post_resource_exhausted()) {
 941     JvmtiExport::post_resource_exhausted(
 942         JVMTI_RESOURCE_EXHAUSTED_OOM_ERROR,
 943         space_string);
 944   }
 945 
 946   if (!is_init_completed()) {
 947     vm_exit_during_initialization("OutOfMemoryError", space_string);
 948   }
 949 
 950   if (out_of_compressed_class_space) {
 951     THROW_OOP(Universe::out_of_memory_error_class_metaspace());
 952   } else {
 953     THROW_OOP(Universe::out_of_memory_error_metaspace());
 954   }
 955 }
 956 
 957 const char* Metaspace::metadata_type_name(Metaspace::MetadataType mdtype) {
 958   switch (mdtype) {
 959     case Metaspace::ClassType: return "Class";
 960     case Metaspace::NonClassType: return "Metadata";
 961     default:
 962       assert(false, "Got bad mdtype: %d", (int) mdtype);
 963       return nullptr;
 964   }
 965 }
 966 
 967 void Metaspace::purge(bool classes_unloaded) {
 968   // The MetaspaceCritical_lock is used by a concurrent GC to block out concurrent metaspace
 969   // allocations, that would starve critical metaspace allocations, that are about to throw
 970   // OOM if they fail; they need precedence for correctness.
 971   MutexLocker ml(MetaspaceCritical_lock, Mutex::_no_safepoint_check_flag);
 972   if (classes_unloaded) {
 973     ChunkManager* cm = ChunkManager::chunkmanager_nonclass();
 974     if (cm != nullptr) {
 975       cm->purge();
 976     }
 977     if (using_class_space()) {
 978       cm = ChunkManager::chunkmanager_class();
 979       if (cm != nullptr) {
 980         cm->purge();
 981       }
 982     }
 983   }
 984 
 985   // Try to satisfy queued metaspace allocation requests.
 986   //
 987   // It might seem unnecessary to try to process allocation requests if no
 988   // classes have been unloaded. However, this call is required for the code
 989   // in MetaspaceCriticalAllocation::try_allocate_critical to work.
 990   MetaspaceCriticalAllocation::process();
 991 }
 992 
 993 // Returns true if pointer points into one of the metaspace regions, or
 994 // into the class space.
 995 bool Metaspace::is_in_shared_metaspace(const void* ptr) {
 996   return MetaspaceShared::is_in_shared_metaspace(ptr);

 997 }
 998 
 999 // Returns true if pointer points into one of the non-class-space metaspace regions.
1000 bool Metaspace::is_in_nonclass_metaspace(const void* ptr) {



1001   return VirtualSpaceList::vslist_nonclass()->contains((MetaWord*)ptr);
1002 }
--- EOF ---