1 /*
   2  * Copyright (c) 2012, 2019, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 #include "precompiled.hpp"
  25 #include "jvm.h"
  26 
  27 #include "runtime/orderAccess.hpp"
  28 #include "runtime/vmThread.hpp"
  29 #include "runtime/vmOperations.hpp"
  30 #include "services/memBaseline.hpp"
  31 #include "services/memReporter.hpp"
  32 #include "services/mallocTracker.inline.hpp"
  33 #include "services/memTracker.hpp"
  34 #include "services/threadStackTracker.hpp"
  35 #include "utilities/debug.hpp"
  36 #include "utilities/defaultStream.hpp"
  37 #include "utilities/vmError.hpp"
  38 
  39 #ifdef _WINDOWS
  40 #include <windows.h>
  41 #endif
  42 
  43 #ifdef SOLARIS
  44   volatile bool NMT_stack_walkable = false;
  45 #else
  46   volatile bool NMT_stack_walkable = true;
  47 #endif
  48 
  49 volatile NMT_TrackingLevel MemTracker::_tracking_level = NMT_unknown;
  50 NMT_TrackingLevel MemTracker::_cmdline_tracking_level = NMT_unknown;
  51 
  52 MemBaseline MemTracker::_baseline;
  53 bool MemTracker::_is_nmt_env_valid = true;
  54 
  55 static const size_t buffer_size = 64;
  56 
  57 NMT_TrackingLevel MemTracker::init_tracking_level() {
  58   // Memory type is encoded into tracking header as a byte field,
  59   // make sure that we don't overflow it.
  60   STATIC_ASSERT(mt_number_of_types <= max_jubyte);
  61 
  62   char nmt_env_variable[buffer_size];
  63   jio_snprintf(nmt_env_variable, sizeof(nmt_env_variable), "NMT_LEVEL_%d", os::current_process_id());
  64   const char* nmt_env_value;
  65 #ifdef _WINDOWS
  66   // Read the NMT environment variable from the PEB instead of the CRT
  67   char value[buffer_size];
  68   nmt_env_value = GetEnvironmentVariable(nmt_env_variable, value, (DWORD)sizeof(value)) != 0 ? value : NULL;
  69 #else
  70   nmt_env_value = ::getenv(nmt_env_variable);
  71 #endif
  72   NMT_TrackingLevel level = NMT_off;
  73   if (nmt_env_value != NULL) {
  74     if (strcmp(nmt_env_value, "summary") == 0) {
  75       level = NMT_summary;
  76     } else if (strcmp(nmt_env_value, "detail") == 0) {
  77       level = NMT_detail;
  78     } else if (strcmp(nmt_env_value, "off") != 0) {
  79       // The value of the environment variable is invalid
  80       _is_nmt_env_valid = false;
  81     }
  82     // Remove the environment variable to avoid leaking to child processes
  83     os::unsetenv(nmt_env_variable);
  84   }
  85 
  86   if (!MallocTracker::initialize(level) ||
  87       !VirtualMemoryTracker::initialize(level)) {
  88     level = NMT_off;
  89   }
  90   return level;
  91 }
  92 
  93 void MemTracker::init() {
  94   NMT_TrackingLevel level = tracking_level();
  95   if (level >= NMT_summary) {
  96     if (!VirtualMemoryTracker::late_initialize(level) ||
  97         !ThreadStackTracker::late_initialize(level)) {
  98       shutdown();
  99       return;
 100     }
 101   }
 102 }
 103 
 104 bool MemTracker::check_launcher_nmt_support(const char* value) {
 105   if (strcmp(value, "=detail") == 0) {
 106     if (MemTracker::tracking_level() != NMT_detail) {
 107       return false;
 108     }
 109   } else if (strcmp(value, "=summary") == 0) {
 110     if (MemTracker::tracking_level() != NMT_summary) {
 111       return false;
 112     }
 113   } else if (strcmp(value, "=off") == 0) {
 114     if (MemTracker::tracking_level() != NMT_off) {
 115       return false;
 116     }
 117   } else {
 118     _is_nmt_env_valid = false;
 119   }
 120 
 121   return true;
 122 }
 123 
 124 bool MemTracker::verify_nmt_option() {
 125   return _is_nmt_env_valid;
 126 }
 127 
 128 void* MemTracker::malloc_base(void* memblock) {
 129   return MallocTracker::get_base(memblock);
 130 }
 131 
 132 void Tracker::record(address addr, size_t size) {
 133   if (MemTracker::tracking_level() < NMT_summary) return;
 134   switch(_type) {
 135     case uncommit:
 136       VirtualMemoryTracker::remove_uncommitted_region(addr, size);
 137       break;
 138     case release:
 139       VirtualMemoryTracker::remove_released_region(addr, size);
 140         break;
 141     default:
 142       ShouldNotReachHere();
 143   }
 144 }
 145 
 146 
 147 // Shutdown can only be issued via JCmd, and NMT JCmd is serialized by lock
 148 void MemTracker::shutdown() {
 149   // We can only shutdown NMT to minimal tracking level if it is ever on.
 150   if (tracking_level() > NMT_minimal) {
 151     transition_to(NMT_minimal);
 152   }
 153 }
 154 
 155 bool MemTracker::transition_to(NMT_TrackingLevel level) {
 156   NMT_TrackingLevel current_level = tracking_level();
 157 
 158   assert(level != NMT_off || current_level == NMT_off, "Cannot transition NMT to off");
 159 
 160   if (current_level == level) {
 161     return true;
 162   } else if (current_level > level) {
 163     // Downgrade tracking level, we want to lower the tracking level first
 164     _tracking_level = level;
 165     // Make _tracking_level visible immediately.
 166     OrderAccess::fence();
 167     VirtualMemoryTracker::transition(current_level, level);
 168     MallocTracker::transition(current_level, level);
 169     ThreadStackTracker::transition(current_level, level);
 170   } else {
 171     // Upgrading tracking level is not supported and has never been supported.
 172     // Allocating and deallocating malloc tracking structures is not thread safe and
 173     // leads to inconsistencies unless a lot coarser locks are added.
 174   }
 175   return true;
 176 }
 177 
 178 
 179 static volatile bool g_final_report_did_run = false;
 180 void MemTracker::final_report(outputStream* output) {
 181   // This function is called during both error reporting and normal VM exit.
 182   // However, it should only ever run once.  E.g. if the VM crashes after
 183   // printing the final report during normal VM exit, it should not print
 184   // the final report again. In addition, it should be guarded from
 185   // recursive calls in case NMT reporting itself crashes.
 186   if (Atomic::cmpxchg(true, &g_final_report_did_run, false) == false) {
 187     NMT_TrackingLevel level = tracking_level();
 188     if (level >= NMT_summary) {
 189       report(level == NMT_summary, output);
 190     }
 191   }
 192 }
 193 
 194 void MemTracker::report(bool summary_only, outputStream* output) {
 195  assert(output != NULL, "No output stream");
 196   MemBaseline baseline;
 197   if (baseline.baseline(summary_only)) {
 198     if (summary_only) {
 199       MemSummaryReporter rpt(baseline, output);
 200       rpt.report();
 201     } else {
 202       MemDetailReporter rpt(baseline, output);
 203       rpt.report();
 204       output->print("Metaspace:");
 205       // The basic metaspace report avoids any locking and should be safe to
 206       // be called at any time.
 207       MetaspaceUtils::print_basic_report(output, K);
 208     }
 209   }
 210 }
 211 
 212 // This is a walker to gather malloc site hashtable statistics,
 213 // the result is used for tuning.
 214 class StatisticsWalker : public MallocSiteWalker {
 215  private:
 216   enum Threshold {
 217     // aggregates statistics over this threshold into one
 218     // line item.
 219     report_threshold = 20
 220   };
 221 
 222  private:
 223   // Number of allocation sites that have all memory freed
 224   int   _empty_entries;
 225   // Total number of allocation sites, include empty sites
 226   int   _total_entries;
 227   // Number of captured call stack distribution
 228   int   _stack_depth_distribution[NMT_TrackingStackDepth];
 229   // Hash distribution
 230   int   _hash_distribution[report_threshold];
 231   // Number of hash buckets that have entries over the threshold
 232   int   _bucket_over_threshold;
 233 
 234   // The hash bucket that walker is currently walking
 235   int   _current_hash_bucket;
 236   // The length of current hash bucket
 237   int   _current_bucket_length;
 238   // Number of hash buckets that are not empty
 239   int   _used_buckets;
 240   // Longest hash bucket length
 241   int   _longest_bucket_length;
 242 
 243  public:
 244   StatisticsWalker() : _empty_entries(0), _total_entries(0) {
 245     int index = 0;
 246     for (index = 0; index < NMT_TrackingStackDepth; index ++) {
 247       _stack_depth_distribution[index] = 0;
 248     }
 249     for (index = 0; index < report_threshold; index ++) {
 250       _hash_distribution[index] = 0;
 251     }
 252     _bucket_over_threshold = 0;
 253     _longest_bucket_length = 0;
 254     _current_hash_bucket = -1;
 255     _current_bucket_length = 0;
 256     _used_buckets = 0;
 257   }
 258 
 259   virtual bool do_malloc_site(const MallocSite* e) {
 260     if (e->size() == 0) _empty_entries ++;
 261     _total_entries ++;
 262 
 263     // stack depth distrubution
 264     int frames = e->call_stack()->frames();
 265     _stack_depth_distribution[frames - 1] ++;
 266 
 267     // hash distribution
 268     int hash_bucket = e->hash() % MallocSiteTable::hash_buckets();
 269     if (_current_hash_bucket == -1) {
 270       _current_hash_bucket = hash_bucket;
 271       _current_bucket_length = 1;
 272     } else if (_current_hash_bucket == hash_bucket) {
 273       _current_bucket_length ++;
 274     } else {
 275       record_bucket_length(_current_bucket_length);
 276       _current_hash_bucket = hash_bucket;
 277       _current_bucket_length = 1;
 278     }
 279     return true;
 280   }
 281 
 282   // walk completed
 283   void completed() {
 284     record_bucket_length(_current_bucket_length);
 285   }
 286 
 287   void report_statistics(outputStream* out) {
 288     int index;
 289     out->print_cr("Malloc allocation site table:");
 290     out->print_cr("\tTotal entries: %d", _total_entries);
 291     out->print_cr("\tEmpty entries: %d (%2.2f%%)", _empty_entries, ((float)_empty_entries * 100) / _total_entries);
 292     out->print_cr(" ");
 293     out->print_cr("Hash distribution:");
 294     if (_used_buckets < MallocSiteTable::hash_buckets()) {
 295       out->print_cr("empty bucket: %d", (MallocSiteTable::hash_buckets() - _used_buckets));
 296     }
 297     for (index = 0; index < report_threshold; index ++) {
 298       if (_hash_distribution[index] != 0) {
 299         if (index == 0) {
 300           out->print_cr("  %d    entry: %d", 1, _hash_distribution[0]);
 301         } else if (index < 9) { // single digit
 302           out->print_cr("  %d  entries: %d", (index + 1), _hash_distribution[index]);
 303         } else {
 304           out->print_cr(" %d entries: %d", (index + 1), _hash_distribution[index]);
 305         }
 306       }
 307     }
 308     if (_bucket_over_threshold > 0) {
 309       out->print_cr(" >%d entries: %d", report_threshold,  _bucket_over_threshold);
 310     }
 311     out->print_cr("most entries: %d", _longest_bucket_length);
 312     out->print_cr(" ");
 313     out->print_cr("Call stack depth distribution:");
 314     for (index = 0; index < NMT_TrackingStackDepth; index ++) {
 315       if (_stack_depth_distribution[index] > 0) {
 316         out->print_cr("\t%d: %d", index + 1, _stack_depth_distribution[index]);
 317       }
 318     }
 319   }
 320 
 321  private:
 322   void record_bucket_length(int length) {
 323     _used_buckets ++;
 324     if (length <= report_threshold) {
 325       _hash_distribution[length - 1] ++;
 326     } else {
 327       _bucket_over_threshold ++;
 328     }
 329     _longest_bucket_length = MAX2(_longest_bucket_length, length);
 330   }
 331 };
 332 
 333 
 334 void MemTracker::tuning_statistics(outputStream* out) {
 335   // NMT statistics
 336   StatisticsWalker walker;
 337   MallocSiteTable::walk_malloc_site(&walker);
 338   walker.completed();
 339 
 340   out->print_cr("Native Memory Tracking Statistics:");
 341   out->print_cr("Malloc allocation site table size: %d", MallocSiteTable::hash_buckets());
 342   out->print_cr("             Tracking stack depth: %d", NMT_TrackingStackDepth);
 343   NOT_PRODUCT(out->print_cr("Peak concurrent access: %d", MallocSiteTable::access_peak_count());)
 344   out->print_cr(" ");
 345   walker.report_statistics(out);
 346 }
--- EOF ---