includes/libs/rdbms/TransactionProfiler.php

   1 <?php
   2 /**
   3  * Transaction profiling for contention
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Profiler
  22  */
  23
  24 namespace Wikimedia\Rdbms;
  25
  26 use Psr\Log\LoggerInterface;
  27 use Psr\Log\LoggerAwareInterface;
  28 use Psr\Log\NullLogger;
  29 use RuntimeException;
  30
  31 /**
  32  * Helper class that detects high-contention DB queries via profiling calls
  33  *
  34  * This class is meant to work with an IDatabase object, which manages queries
  35  *
  36  * @since 1.24
  37  */
  38 class TransactionProfiler implements LoggerAwareInterface {
  39         /** @var float Seconds */
  40         protected $dbLockThreshold = 3.0;
  41         /** @var float Seconds */
  42         protected $eventThreshold = 0.25;
  43         /** @var bool */
  44         protected $silenced = false;
  45
  46         /** @var array transaction ID => (write start time, list of DBs involved) */
  47         protected $dbTrxHoldingLocks = [];
  48         /** @var array transaction ID => list of (query name, start time, end time) */
  49         protected $dbTrxMethodTimes = [];
  50
  51         /** @var array */
  52         protected $hits = [
  53                 'writes'      => 0,
  54                 'queries'     => 0,
  55                 'conns'       => 0,
  56                 'masterConns' => 0
  57         ];
  58         /** @var array */
  59         protected $expect = [
  60                 'writes'         => INF,
  61                 'queries'        => INF,
  62                 'conns'          => INF,
  63                 'masterConns'    => INF,
  64                 'maxAffected'    => INF,
  65                 'readQueryRows'  => INF,
  66                 'readQueryTime'  => INF,
  67                 'writeQueryTime' => INF
  68         ];
  69         /** @var array */
  70         protected $expectBy = [];
  71
  72         /**
  73          * @var LoggerInterface
  74          */
  75         private $logger;
  76
  77         public function __construct() {
  78                 $this->setLogger( new NullLogger() );
  79         }
  80
  81         public function setLogger( LoggerInterface $logger ) {
  82                 $this->logger = $logger;
  83         }
  84
  85         /**
  86          * @param bool $value
  87          * @return bool Old value
  88          * @since 1.28
  89          */
  90         public function setSilenced( $value ) {
  91                 $old = $this->silenced;
  92                 $this->silenced = $value;
  93
  94                 return $old;
  95         }
  96
  97         /**
  98          * Set performance expectations
  99          *
 100          * With conflicting expectations, the most narrow ones will be used
 101          *
 102          * @param string $event (writes,queries,conns,mConns)
 103          * @param int $value Maximum count of the event
 104          * @param string $fname Caller
 105          * @since 1.25
 106          */
 107         public function setExpectation( $event, $value, $fname ) {
 108                 $this->expect[$event] = isset( $this->expect[$event] )
 109                         ? min( $this->expect[$event], $value )
 110                         : $value;
 111                 if ( $this->expect[$event] == $value ) {
 112                         $this->expectBy[$event] = $fname;
 113                 }
 114         }
 115
 116         /**
 117          * Set multiple performance expectations
 118          *
 119          * With conflicting expectations, the most narrow ones will be used
 120          *
 121          * @param array $expects Map of (event => limit)
 122          * @param string $fname
 123          * @since 1.26
 124          */
 125         public function setExpectations( array $expects, $fname ) {
 126                 foreach ( $expects as $event => $value ) {
 127                         $this->setExpectation( $event, $value, $fname );
 128                 }
 129         }
 130
 131         /**
 132          * Reset performance expectations and hit counters
 133          *
 134          * @since 1.25
 135          */
 136         public function resetExpectations() {
 137                 foreach ( $this->hits as &$val ) {
 138                         $val = 0;
 139                 }
 140                 unset( $val );
 141                 foreach ( $this->expect as &$val ) {
 142                         $val = INF;
 143                 }
 144                 unset( $val );
 145                 $this->expectBy = [];
 146         }
 147
 148         /**
 149          * Mark a DB as having been connected to with a new handle
 150          *
 151          * Note that there can be multiple connections to a single DB.
 152          *
 153          * @param string $server DB server
 154          * @param string $db DB name
 155          * @param bool $isMaster
 156          */
 157         public function recordConnection( $server, $db, $isMaster ) {
 158                 // Report when too many connections happen...
 159                 if ( $this->hits['conns']++ >= $this->expect['conns'] ) {
 160                         $this->reportExpectationViolated(
 161                                 'conns', "[connect to $server ($db)]", $this->hits['conns'] );
 162                 }
 163                 if ( $isMaster && $this->hits['masterConns']++ >= $this->expect['masterConns'] ) {
 164                         $this->reportExpectationViolated(
 165                                 'masterConns', "[connect to $server ($db)]", $this->hits['masterConns'] );
 166                 }
 167         }
 168
 169         /**
 170          * Mark a DB as in a transaction with one or more writes pending
 171          *
 172          * Note that there can be multiple connections to a single DB.
 173          *
 174          * @param string $server DB server
 175          * @param string $db DB name
 176          * @param string $id ID string of transaction
 177          */
 178         public function transactionWritingIn( $server, $db, $id ) {
 179                 $name = "{$server} ({$db}) (TRX#$id)";
 180                 if ( isset( $this->dbTrxHoldingLocks[$name] ) ) {
 181                         $this->logger->warning( "Nested transaction for '$name' - out of sync." );
 182                 }
 183                 $this->dbTrxHoldingLocks[$name] = [
 184                         'start' => microtime( true ),
 185                         'conns' => [], // all connections involved
 186                 ];
 187                 $this->dbTrxMethodTimes[$name] = [];
 188
 189                 foreach ( $this->dbTrxHoldingLocks as $name => &$info ) {
 190                         // Track all DBs in transactions for this transaction
 191                         $info['conns'][$name] = 1;
 192                 }
 193         }
 194
 195         /**
 196          * Register the name and time of a method for slow DB trx detection
 197          *
 198          * This assumes that all queries are synchronous (non-overlapping)
 199          *
 200          * @param string $query Function name or generalized SQL
 201          * @param float $sTime Starting UNIX wall time
 202          * @param bool $isWrite Whether this is a write query
 203          * @param int $n Number of affected/read rows
 204          */
 205         public function recordQueryCompletion( $query, $sTime, $isWrite = false, $n = 0 ) {
 206                 $eTime = microtime( true );
 207                 $elapsed = ( $eTime - $sTime );
 208
 209                 if ( $isWrite && $n > $this->expect['maxAffected'] ) {
 210                         $this->logger->warning(
 211                                 "Query affected $n row(s):\n" . $query . "\n" .
 212                                 ( new RuntimeException() )->getTraceAsString() );
 213                 } elseif ( !$isWrite && $n > $this->expect['readQueryRows'] ) {
 214                         $this->logger->warning(
 215                                 "Query returned $n row(s):\n" . $query . "\n" .
 216                                 ( new RuntimeException() )->getTraceAsString() );
 217                 }
 218
 219                 // Report when too many writes/queries happen...
 220                 if ( $this->hits['queries']++ >= $this->expect['queries'] ) {
 221                         $this->reportExpectationViolated( 'queries', $query, $this->hits['queries'] );
 222                 }
 223                 if ( $isWrite && $this->hits['writes']++ >= $this->expect['writes'] ) {
 224                         $this->reportExpectationViolated( 'writes', $query, $this->hits['writes'] );
 225                 }
 226                 // Report slow queries...
 227                 if ( !$isWrite && $elapsed > $this->expect['readQueryTime'] ) {
 228                         $this->reportExpectationViolated( 'readQueryTime', $query, $elapsed );
 229                 }
 230                 if ( $isWrite && $elapsed > $this->expect['writeQueryTime'] ) {
 231                         $this->reportExpectationViolated( 'writeQueryTime', $query, $elapsed );
 232                 }
 233
 234                 if ( !$this->dbTrxHoldingLocks ) {
 235                         // Short-circuit
 236                         return;
 237                 } elseif ( !$isWrite && $elapsed < $this->eventThreshold ) {
 238                         // Not an important query nor slow enough
 239                         return;
 240                 }
 241
 242                 foreach ( $this->dbTrxHoldingLocks as $name => $info ) {
 243                         $lastQuery = end( $this->dbTrxMethodTimes[$name] );
 244                         if ( $lastQuery ) {
 245                                 // Additional query in the trx...
 246                                 $lastEnd = $lastQuery[2];
 247                                 if ( $sTime >= $lastEnd ) { // sanity check
 248                                         if ( ( $sTime - $lastEnd ) > $this->eventThreshold ) {
 249                                                 // Add an entry representing the time spent doing non-queries
 250                                                 $this->dbTrxMethodTimes[$name][] = [ '...delay...', $lastEnd, $sTime ];
 251                                         }
 252                                         $this->dbTrxMethodTimes[$name][] = [ $query, $sTime, $eTime ];
 253                                 }
 254                         } else {
 255                                 // First query in the trx...
 256                                 if ( $sTime >= $info['start'] ) { // sanity check
 257                                         $this->dbTrxMethodTimes[$name][] = [ $query, $sTime, $eTime ];
 258                                 }
 259                         }
 260                 }
 261         }
 262
 263         /**
 264          * Mark a DB as no longer in a transaction
 265          *
 266          * This will check if locks are possibly held for longer than
 267          * needed and log any affected transactions to a special DB log.
 268          * Note that there can be multiple connections to a single DB.
 269          *
 270          * @param string $server DB server
 271          * @param string $db DB name
 272          * @param string $id ID string of transaction
 273          * @param float $writeTime Time spent in write queries
 274          * @param int $affected Number of rows affected by writes
 275          */
 276         public function transactionWritingOut( $server, $db, $id, $writeTime = 0.0, $affected = 0 ) {
 277                 $name = "{$server} ({$db}) (TRX#$id)";
 278                 if ( !isset( $this->dbTrxMethodTimes[$name] ) ) {
 279                         $this->logger->warning( "Detected no transaction for '$name' - out of sync." );
 280                         return;
 281                 }
 282
 283                 $slow = false;
 284
 285                 // Warn if too much time was spend writing...
 286                 if ( $writeTime > $this->expect['writeQueryTime'] ) {
 287                         $this->reportExpectationViolated(
 288                                 'writeQueryTime',
 289                                 "[transaction $id writes to {$server} ({$db})]",
 290                                 $writeTime
 291                         );
 292                         $slow = true;
 293                 }
 294                 // Warn if too many rows were changed...
 295                 if ( $affected > $this->expect['maxAffected'] ) {
 296                         $this->reportExpectationViolated(
 297                                 'maxAffected',
 298                                 "[transaction $id writes to {$server} ({$db})]",
 299                                 $affected
 300                         );
 301                 }
 302                 // Fill in the last non-query period...
 303                 $lastQuery = end( $this->dbTrxMethodTimes[$name] );
 304                 if ( $lastQuery ) {
 305                         $now = microtime( true );
 306                         $lastEnd = $lastQuery[2];
 307                         if ( ( $now - $lastEnd ) > $this->eventThreshold ) {
 308                                 $this->dbTrxMethodTimes[$name][] = [ '...delay...', $lastEnd, $now ];
 309                         }
 310                 }
 311                 // Check for any slow queries or non-query periods...
 312                 foreach ( $this->dbTrxMethodTimes[$name] as $info ) {
 313                         $elapsed = ( $info[2] - $info[1] );
 314                         if ( $elapsed >= $this->dbLockThreshold ) {
 315                                 $slow = true;
 316                                 break;
 317                         }
 318                 }
 319                 if ( $slow ) {
 320                         $trace = '';
 321                         foreach ( $this->dbTrxMethodTimes[$name] as $i => $info ) {
 322                                 list( $query, $sTime, $end ) = $info;
 323                                 $trace .= sprintf( "%d\t%.6f\t%s\n", $i, ( $end - $sTime ), $query );
 324                         }
 325                         $this->logger->warning( "Sub-optimal transaction on DB(s) [{dbs}]: \n{trace}", [
 326                                 'dbs' => implode( ', ', array_keys( $this->dbTrxHoldingLocks[$name]['conns'] ) ),
 327                                 'trace' => $trace
 328                         ] );
 329                 }
 330                 unset( $this->dbTrxHoldingLocks[$name] );
 331                 unset( $this->dbTrxMethodTimes[$name] );
 332         }
 333
 334         /**
 335          * @param string $expect
 336          * @param string $query
 337          * @param string|float|int $actual
 338          */
 339         protected function reportExpectationViolated( $expect, $query, $actual ) {
 340                 if ( $this->silenced ) {
 341                         return;
 342                 }
 343
 344                 $this->logger->warning(
 345                         "Expectation ({measure} <= {max}) by {by} not met (actual: {actual}):\n{query}\n" .
 346                         ( new RuntimeException() )->getTraceAsString(),
 347                         [
 348                                 'measure' => $expect,
 349                                 'max' => $this->expect[$expect],
 350                                 'by' => $this->expectBy[$expect],
 351                                 'actual' => $actual,
 352                                 'query' => $query
 353                         ]
 354                 );
 355         }
 356 }