1 /* 2 * Copyright (c) 2012, 2020, 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/atomic.hpp" 28 #include "runtime/orderAccess.hpp" 29 #include "runtime/vmThread.hpp" 30 #include "runtime/vmOperations.hpp" 31 #include "services/memBaseline.hpp" 32 #include "services/memReporter.hpp" 33 #include "services/mallocTracker.inline.hpp" 34 #include "services/memTracker.hpp" 35 #include "services/threadStackTracker.hpp" 36 #include "utilities/debug.hpp" 37 #include "utilities/defaultStream.hpp" 38 #include "utilities/vmError.hpp" 39 40 #ifdef _WINDOWS 41 #include <windows.h> 42 #endif 43 44 volatile NMT_TrackingLevel MemTracker::_tracking_level = NMT_unknown; 45 NMT_TrackingLevel MemTracker::_cmdline_tracking_level = NMT_unknown; 46 47 MemBaseline MemTracker::_baseline; 48 bool MemTracker::_is_nmt_env_valid = true; 49 50 static const size_t buffer_size = 64; 51 52 NMT_TrackingLevel MemTracker::init_tracking_level() { 53 // Memory type is encoded into tracking header as a byte field, 54 // make sure that we don't overflow it. 55 STATIC_ASSERT(mt_number_of_types <= max_jubyte); 56 57 char nmt_env_variable[buffer_size]; 58 jio_snprintf(nmt_env_variable, sizeof(nmt_env_variable), "NMT_LEVEL_%d", os::current_process_id()); 59 const char* nmt_env_value; 60 #ifdef _WINDOWS 61 // Read the NMT environment variable from the PEB instead of the CRT 62 char value[buffer_size]; 63 nmt_env_value = GetEnvironmentVariable(nmt_env_variable, value, (DWORD)sizeof(value)) != 0 ? value : NULL; 64 #else 65 nmt_env_value = ::getenv(nmt_env_variable); 66 #endif 67 NMT_TrackingLevel level = NMT_off; 68 if (nmt_env_value != NULL) { 69 if (strcmp(nmt_env_value, "summary") == 0) { 70 level = NMT_summary; 71 } else if (strcmp(nmt_env_value, "detail") == 0) { 72 level = NMT_detail; 73 } else if (strcmp(nmt_env_value, "off") != 0) { 74 // The value of the environment variable is invalid 75 _is_nmt_env_valid = false; 76 } 77 // Remove the environment variable to avoid leaking to child processes 78 os::unsetenv(nmt_env_variable); 79 } 80 81 if (!MallocTracker::initialize(level) || 82 !VirtualMemoryTracker::initialize(level)) { 83 level = NMT_off; 84 } 85 return level; 86 } 87 88 void MemTracker::init() { 89 NMT_TrackingLevel level = tracking_level(); 90 if (level >= NMT_summary) { 91 if (!VirtualMemoryTracker::late_initialize(level) || 92 !ThreadStackTracker::late_initialize(level)) { 93 shutdown(); 94 return; 95 } 96 } 97 } 98 99 bool MemTracker::check_launcher_nmt_support(const char* value) { 100 if (strcmp(value, "=detail") == 0) { 101 if (MemTracker::tracking_level() != NMT_detail) { 102 return false; 103 } 104 } else if (strcmp(value, "=summary") == 0) { 105 if (MemTracker::tracking_level() != NMT_summary) { 106 return false; 107 } 108 } else if (strcmp(value, "=off") == 0) { 109 if (MemTracker::tracking_level() != NMT_off) { 110 return false; 111 } 112 } else { 113 _is_nmt_env_valid = false; 114 } 115 116 return true; 117 } 118 119 bool MemTracker::verify_nmt_option() { 120 return _is_nmt_env_valid; 121 } 122 123 void* MemTracker::malloc_base(void* memblock) { 124 return MallocTracker::get_base(memblock); 125 } 126 127 void Tracker::record(address addr, size_t size) { 128 if (MemTracker::tracking_level() < NMT_summary) return; 129 switch(_type) { 130 case uncommit: 131 VirtualMemoryTracker::remove_uncommitted_region(addr, size); 132 break; 133 case release: 134 VirtualMemoryTracker::remove_released_region(addr, size); 135 break; 136 default: 137 ShouldNotReachHere(); 138 } 139 } 140 141 142 // Shutdown can only be issued via JCmd, and NMT JCmd is serialized by lock 143 void MemTracker::shutdown() { 144 // We can only shutdown NMT to minimal tracking level if it is ever on. 145 if (tracking_level() > NMT_minimal) { 146 transition_to(NMT_minimal); 147 } 148 } 149 150 bool MemTracker::transition_to(NMT_TrackingLevel level) { 151 NMT_TrackingLevel current_level = tracking_level(); 152 153 assert(level != NMT_off || current_level == NMT_off, "Cannot transition NMT to off"); 154 155 if (current_level == level) { 156 return true; 157 } else if (current_level > level) { 158 // Downgrade tracking level, we want to lower the tracking level first 159 _tracking_level = level; 160 // Make _tracking_level visible immediately. 161 OrderAccess::fence(); 162 VirtualMemoryTracker::transition(current_level, level); 163 MallocTracker::transition(current_level, level); 164 ThreadStackTracker::transition(current_level, level); 165 } else { 166 // Upgrading tracking level is not supported and has never been supported. 167 // Allocating and deallocating malloc tracking structures is not thread safe and 168 // leads to inconsistencies unless a lot coarser locks are added. 169 } 170 return true; 171 } 172 173 174 static volatile bool g_final_report_did_run = false; 175 void MemTracker::final_report(outputStream* output) { 176 // This function is called during both error reporting and normal VM exit. 177 // However, it should only ever run once. E.g. if the VM crashes after 178 // printing the final report during normal VM exit, it should not print 179 // the final report again. In addition, it should be guarded from 180 // recursive calls in case NMT reporting itself crashes. 181 if (Atomic::cmpxchg(&g_final_report_did_run, false, true) == false) { 182 NMT_TrackingLevel level = tracking_level(); 183 if (level >= NMT_summary) { 184 report(level == NMT_summary, output); 185 } 186 } 187 } 188 189 void MemTracker::report(bool summary_only, outputStream* output) { 190 assert(output != NULL, "No output stream"); 191 MemBaseline baseline; 192 if (baseline.baseline(summary_only)) { 193 if (summary_only) { 194 MemSummaryReporter rpt(baseline, output); 195 rpt.report(); 196 } else { 197 MemDetailReporter rpt(baseline, output); 198 rpt.report(); 199 output->print("Metaspace:"); 200 // The basic metaspace report avoids any locking and should be safe to 201 // be called at any time. 202 MetaspaceUtils::print_basic_report(output, K); 203 } 204 } 205 } 206 207 // This is a walker to gather malloc site hashtable statistics, 208 // the result is used for tuning. 209 class StatisticsWalker : public MallocSiteWalker { 210 private: 211 enum Threshold { 212 // aggregates statistics over this threshold into one 213 // line item. 214 report_threshold = 20 215 }; 216 217 private: 218 // Number of allocation sites that have all memory freed 219 int _empty_entries; 220 // Total number of allocation sites, include empty sites 221 int _total_entries; 222 // Number of captured call stack distribution 223 int _stack_depth_distribution[NMT_TrackingStackDepth]; 224 // Hash distribution 225 int _hash_distribution[report_threshold]; 226 // Number of hash buckets that have entries over the threshold 227 int _bucket_over_threshold; 228 229 // The hash bucket that walker is currently walking 230 int _current_hash_bucket; 231 // The length of current hash bucket 232 int _current_bucket_length; 233 // Number of hash buckets that are not empty 234 int _used_buckets; 235 // Longest hash bucket length 236 int _longest_bucket_length; 237 238 public: 239 StatisticsWalker() : _empty_entries(0), _total_entries(0) { 240 int index = 0; 241 for (index = 0; index < NMT_TrackingStackDepth; index ++) { 242 _stack_depth_distribution[index] = 0; 243 } 244 for (index = 0; index < report_threshold; index ++) { 245 _hash_distribution[index] = 0; 246 } 247 _bucket_over_threshold = 0; 248 _longest_bucket_length = 0; 249 _current_hash_bucket = -1; 250 _current_bucket_length = 0; 251 _used_buckets = 0; 252 } 253 254 virtual bool do_malloc_site(const MallocSite* e) { 255 if (e->size() == 0) _empty_entries ++; 256 _total_entries ++; 257 258 // stack depth distrubution 259 int frames = e->call_stack()->frames(); 260 _stack_depth_distribution[frames - 1] ++; 261 262 // hash distribution 263 int hash_bucket = e->hash() % MallocSiteTable::hash_buckets(); 264 if (_current_hash_bucket == -1) { 265 _current_hash_bucket = hash_bucket; 266 _current_bucket_length = 1; 267 } else if (_current_hash_bucket == hash_bucket) { 268 _current_bucket_length ++; 269 } else { 270 record_bucket_length(_current_bucket_length); 271 _current_hash_bucket = hash_bucket; 272 _current_bucket_length = 1; 273 } 274 return true; 275 } 276 277 // walk completed 278 void completed() { 279 record_bucket_length(_current_bucket_length); 280 } 281 282 void report_statistics(outputStream* out) { 283 int index; 284 out->print_cr("Malloc allocation site table:"); 285 out->print_cr("\tTotal entries: %d", _total_entries); 286 out->print_cr("\tEmpty entries: %d (%2.2f%%)", _empty_entries, ((float)_empty_entries * 100) / _total_entries); 287 out->print_cr(" "); 288 out->print_cr("Hash distribution:"); 289 if (_used_buckets < MallocSiteTable::hash_buckets()) { 290 out->print_cr("empty bucket: %d", (MallocSiteTable::hash_buckets() - _used_buckets)); 291 } 292 for (index = 0; index < report_threshold; index ++) { 293 if (_hash_distribution[index] != 0) { 294 if (index == 0) { 295 out->print_cr(" %d entry: %d", 1, _hash_distribution[0]); 296 } else if (index < 9) { // single digit 297 out->print_cr(" %d entries: %d", (index + 1), _hash_distribution[index]); 298 } else { 299 out->print_cr(" %d entries: %d", (index + 1), _hash_distribution[index]); 300 } 301 } 302 } 303 if (_bucket_over_threshold > 0) { 304 out->print_cr(" >%d entries: %d", report_threshold, _bucket_over_threshold); 305 } 306 out->print_cr("most entries: %d", _longest_bucket_length); 307 out->print_cr(" "); 308 out->print_cr("Call stack depth distribution:"); 309 for (index = 0; index < NMT_TrackingStackDepth; index ++) { 310 if (_stack_depth_distribution[index] > 0) { 311 out->print_cr("\t%d: %d", index + 1, _stack_depth_distribution[index]); 312 } 313 } 314 } 315 316 private: 317 void record_bucket_length(int length) { 318 _used_buckets ++; 319 if (length <= report_threshold) { 320 _hash_distribution[length - 1] ++; 321 } else { 322 _bucket_over_threshold ++; 323 } 324 _longest_bucket_length = MAX2(_longest_bucket_length, length); 325 } 326 }; 327 328 329 void MemTracker::tuning_statistics(outputStream* out) { 330 // NMT statistics 331 StatisticsWalker walker; 332 MallocSiteTable::walk_malloc_site(&walker); 333 walker.completed(); 334 335 out->print_cr("Native Memory Tracking Statistics:"); 336 out->print_cr("Malloc allocation site table size: %d", MallocSiteTable::hash_buckets()); 337 out->print_cr(" Tracking stack depth: %d", NMT_TrackingStackDepth); 338 NOT_PRODUCT(out->print_cr("Peak concurrent access: %d", MallocSiteTable::access_peak_count());) 339 out->print_cr(" "); 340 walker.report_statistics(out); 341 }