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  * @author Aaron Schulz
  23  */
  24
  25 namespace Wikimedia\Rdbms;
  26
  27 use Psr\Log\LoggerInterface;
  28 use Psr\Log\LoggerAwareInterface;
  29 use Psr\Log\NullLogger;
  30 use RuntimeException;
  31
  32 /**
  33  * Helper class that detects high-contention DB queries via profiling calls
  34  *
  35  * This class is meant to work with an IDatabase object, which manages queries
  36  *
  37  * @since 1.24
  38  */
  39 class TransactionProfiler implements LoggerAwareInterface {
  40         /** @var float Seconds */
  41         protected $dbLockThreshold = 3.0;
  42         /** @var float Seconds */
  43         protected $eventThreshold = .25;
  44         /** @var bool */
  45         protected $silenced = false;
  46
  47         /** @var array transaction ID => (write start time, list of DBs involved) */
  48         protected $dbTrxHoldingLocks = [];
  49         /** @var array transaction ID => list of (query name, start time, end time) */
  50         protected $dbTrxMethodTimes = [];
  51
  52         /** @var array */
  53         protected $hits = [
  54                 'writes'      => 0,
  55                 'queries'     => 0,
  56                 'conns'       => 0,
  57                 'masterConns' => 0
  58         ];
  59         /** @var array */
  60         protected $expect = [
  61                 'writes'         => INF,
  62                 'queries'        => INF,
  63                 'conns'          => INF,
  64                 'masterConns'    => INF,
  65                 'maxAffected'    => 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 New 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 integer $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 $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( 'conns', "[connect to $server ($db)]" );
 161                 }
 162                 if ( $isMaster && $this->hits['masterConns']++ == $this->expect['masterConns'] ) {
 163                         $this->reportExpectationViolated( 'masterConns', "[connect to $server ($db)]" );
 164                 }
 165         }
 166
 167         /**
 168          * Mark a DB as in a transaction with one or more writes pending
 169          *
 170          * Note that there can be multiple connections to a single DB.
 171          *
 172          * @param string $server DB server
 173          * @param string $db DB name
 174          * @param string $id ID string of transaction
 175          */
 176         public function transactionWritingIn( $server, $db, $id ) {
 177                 $name = "{$server} ({$db}) (TRX#$id)";
 178                 if ( isset( $this->dbTrxHoldingLocks[$name] ) ) {
 179                         $this->logger->info( "Nested transaction for '$name' - out of sync." );
 180                 }
 181                 $this->dbTrxHoldingLocks[$name] = [
 182                         'start' => microtime( true ),
 183                         'conns' => [], // all connections involved
 184                 ];
 185                 $this->dbTrxMethodTimes[$name] = [];
 186
 187                 foreach ( $this->dbTrxHoldingLocks as $name => &$info ) {
 188                         // Track all DBs in transactions for this transaction
 189                         $info['conns'][$name] = 1;
 190                 }
 191         }
 192
 193         /**
 194          * Register the name and time of a method for slow DB trx detection
 195          *
 196          * This assumes that all queries are synchronous (non-overlapping)
 197          *
 198          * @param string $query Function name or generalized SQL
 199          * @param float $sTime Starting UNIX wall time
 200          * @param bool $isWrite Whether this is a write query
 201          * @param integer $n Number of affected rows
 202          */
 203         public function recordQueryCompletion( $query, $sTime, $isWrite = false, $n = 0 ) {
 204                 $eTime = microtime( true );
 205                 $elapsed = ( $eTime - $sTime );
 206
 207                 if ( $isWrite && $n > $this->expect['maxAffected'] ) {
 208                         $this->logger->info(
 209                                 "Query affected $n row(s):\n" . $query . "\n" .
 210                                 ( new RuntimeException() )->getTraceAsString() );
 211                 }
 212
 213                 // Report when too many writes/queries happen...
 214                 if ( $this->hits['queries']++ == $this->expect['queries'] ) {
 215                         $this->reportExpectationViolated( 'queries', $query );
 216                 }
 217                 if ( $isWrite && $this->hits['writes']++ == $this->expect['writes'] ) {
 218                         $this->reportExpectationViolated( 'writes', $query );
 219                 }
 220                 // Report slow queries...
 221                 if ( !$isWrite && $elapsed > $this->expect['readQueryTime'] ) {
 222                         $this->reportExpectationViolated( 'readQueryTime', $query, $elapsed );
 223                 }
 224                 if ( $isWrite && $elapsed > $this->expect['writeQueryTime'] ) {
 225                         $this->reportExpectationViolated( 'writeQueryTime', $query, $elapsed );
 226                 }
 227
 228                 if ( !$this->dbTrxHoldingLocks ) {
 229                         // Short-circuit
 230                         return;
 231                 } elseif ( !$isWrite && $elapsed < $this->eventThreshold ) {
 232                         // Not an important query nor slow enough
 233                         return;
 234                 }
 235
 236                 foreach ( $this->dbTrxHoldingLocks as $name => $info ) {
 237                         $lastQuery = end( $this->dbTrxMethodTimes[$name] );
 238                         if ( $lastQuery ) {
 239                                 // Additional query in the trx...
 240                                 $lastEnd = $lastQuery[2];
 241                                 if ( $sTime >= $lastEnd ) { // sanity check
 242                                         if ( ( $sTime - $lastEnd ) > $this->eventThreshold ) {
 243                                                 // Add an entry representing the time spent doing non-queries
 244                                                 $this->dbTrxMethodTimes[$name][] = [ '...delay...', $lastEnd, $sTime ];
 245                                         }
 246                                         $this->dbTrxMethodTimes[$name][] = [ $query, $sTime, $eTime ];
 247                                 }
 248                         } else {
 249                                 // First query in the trx...
 250                                 if ( $sTime >= $info['start'] ) { // sanity check
 251                                         $this->dbTrxMethodTimes[$name][] = [ $query, $sTime, $eTime ];
 252                                 }
 253                         }
 254                 }
 255         }
 256
 257         /**
 258          * Mark a DB as no longer in a transaction
 259          *
 260          * This will check if locks are possibly held for longer than
 261          * needed and log any affected transactions to a special DB log.
 262          * Note that there can be multiple connections to a single DB.
 263          *
 264          * @param string $server DB server
 265          * @param string $db DB name
 266          * @param string $id ID string of transaction
 267          * @param float $writeTime Time spent in write queries
 268          * @param integer $affected Number of rows affected by writes
 269          */
 270         public function transactionWritingOut( $server, $db, $id, $writeTime = 0.0, $affected = 0 ) {
 271                 $name = "{$server} ({$db}) (TRX#$id)";
 272                 if ( !isset( $this->dbTrxMethodTimes[$name] ) ) {
 273                         $this->logger->info( "Detected no transaction for '$name' - out of sync." );
 274                         return;
 275                 }
 276
 277                 $slow = false;
 278
 279                 // Warn if too much time was spend writing...
 280                 if ( $writeTime > $this->expect['writeQueryTime'] ) {
 281                         $this->reportExpectationViolated(
 282                                 'writeQueryTime',
 283                                 "[transaction $id writes to {$server} ({$db})]",
 284                                 $writeTime
 285                         );
 286                         $slow = true;
 287                 }
 288                 // Warn if too many rows were changed...
 289                 if ( $affected > $this->expect['maxAffected'] ) {
 290                         $this->reportExpectationViolated(
 291                                 'maxAffected',
 292                                 "[transaction $id writes to {$server} ({$db})]",
 293                                 $affected
 294                         );
 295                 }
 296                 // Fill in the last non-query period...
 297                 $lastQuery = end( $this->dbTrxMethodTimes[$name] );
 298                 if ( $lastQuery ) {
 299                         $now = microtime( true );
 300                         $lastEnd = $lastQuery[2];
 301                         if ( ( $now - $lastEnd ) > $this->eventThreshold ) {
 302                                 $this->dbTrxMethodTimes[$name][] = [ '...delay...', $lastEnd, $now ];
 303                         }
 304                 }
 305                 // Check for any slow queries or non-query periods...
 306                 foreach ( $this->dbTrxMethodTimes[$name] as $info ) {
 307                         $elapsed = ( $info[2] - $info[1] );
 308                         if ( $elapsed >= $this->dbLockThreshold ) {
 309                                 $slow = true;
 310                                 break;
 311                         }
 312                 }
 313                 if ( $slow ) {
 314                         $trace = '';
 315                         foreach ( $this->dbTrxMethodTimes[$name] as $i => $info ) {
 316                                 list( $query, $sTime, $end ) = $info;
 317                                 $trace .= sprintf( "%d\t%.6f\t%s\n", $i, ( $end - $sTime ), $query );
 318                         }
 319                         $this->logger->info( "Sub-optimal transaction on DB(s) [{dbs}]: \n{trace}", [
 320                                 'dbs' => implode( ', ', array_keys( $this->dbTrxHoldingLocks[$name]['conns'] ) ),
 321                                 'trace' => $trace
 322                         ] );
 323                 }
 324                 unset( $this->dbTrxHoldingLocks[$name] );
 325                 unset( $this->dbTrxMethodTimes[$name] );
 326         }
 327
 328         /**
 329          * @param string $expect
 330          * @param string $query
 331          * @param string|float|int $actual [optional]
 332          */
 333         protected function reportExpectationViolated( $expect, $query, $actual = null ) {
 334                 if ( $this->silenced ) {
 335                         return;
 336                 }
 337
 338                 $n = $this->expect[$expect];
 339                 $by = $this->expectBy[$expect];
 340                 $actual = ( $actual !== null ) ? " (actual: $actual)" : "";
 341
 342                 $this->logger->info(
 343                         "Expectation ($expect <= $n) by $by not met$actual:\n$query\n" .
 344                         ( new RuntimeException() )->getTraceAsString()
 345                 );
 346         }
 347 }