includes/profiler/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 /**
  26  * Helper class that detects high-contention DB queries via profiling calls
  27  *
  28  * This class is meant to work with a DatabaseBase object, which manages queries
  29  *
  30  * @since 1.24
  31  */
  32 class TransactionProfiler {
  33         /** @var float Seconds */
  34         protected $dbLockThreshold = 3.0;
  35         /** @var float Seconds */
  36         protected $eventThreshold = .25;
  37
  38         /** @var array transaction ID => (write start time, list of DBs involved) */
  39         protected $dbTrxHoldingLocks = array();
  40         /** @var array transaction ID => list of (query name, start time, end time) */
  41         protected $dbTrxMethodTimes = array();
  42
  43         /** @var array */
  44         protected $hits = array(
  45                 'writes'      => 0,
  46                 'queries'     => 0,
  47                 'conns'       => 0,
  48                 'masterConns' => 0
  49         );
  50         /** @var array */
  51         protected $expect = array(
  52                 'writes'      => INF,
  53                 'queries'     => INF,
  54                 'conns'       => INF,
  55                 'masterConns' => INF,
  56                 'maxAffected' => INF
  57         );
  58         /** @var array */
  59         protected $expectBy = array();
  60
  61         /**
  62          * Set performance expectations
  63          *
  64          * With conflicting expect, the most specific ones will be used
  65          *
  66          * @param string $event (writes,queries,conns,mConns)
  67          * @param integer $value Maximum count of the event
  68          * @param string $fname Caller
  69          * @since 1.25
  70          */
  71         public function setExpectation( $event, $value, $fname ) {
  72                 $this->expect[$event] = isset( $this->expect[$event] )
  73                         ? min( $this->expect[$event], $value )
  74                         : $value;
  75                 if ( $this->expect[$event] == $value ) {
  76                         $this->expectBy[$event] = $fname;
  77                 }
  78         }
  79
  80         /**
  81          * Reset performance expectations and hit counters
  82          *
  83          * @since 1.25
  84          */
  85         public function resetExpectations() {
  86                 foreach ( $this->hits as &$val ) {
  87                         $val = 0;
  88                 }
  89                 unset( $val );
  90                 foreach ( $this->expect as &$val ) {
  91                         $val = INF;
  92                 }
  93                 unset( $val );
  94                 $this->expectBy = array();
  95         }
  96
  97         /**
  98          * Mark a DB as having been connected to with a new handle
  99          *
 100          * Note that there can be multiple connections to a single DB.
 101          *
 102          * @param string $server DB server
 103          * @param string $db DB name
 104          * @param bool $isMaster
 105          */
 106         public function recordConnection( $server, $db, $isMaster ) {
 107                 // Report when too many connections happen...
 108                 if ( $this->hits['conns']++ == $this->expect['conns'] ) {
 109                         $this->reportExpectationViolated( 'conns', "[connect to $server ($db)]" );
 110                 }
 111                 if ( $isMaster && $this->hits['masterConns']++ == $this->expect['masterConns'] ) {
 112                         $this->reportExpectationViolated( 'masterConns', "[connect to $server ($db)]" );
 113                 }
 114         }
 115
 116         /**
 117          * Mark a DB as in a transaction with one or more writes pending
 118          *
 119          * Note that there can be multiple connections to a single DB.
 120          *
 121          * @param string $server DB server
 122          * @param string $db DB name
 123          * @param string $id ID string of transaction
 124          */
 125         public function transactionWritingIn( $server, $db, $id ) {
 126                 $name = "{$server} ({$db}) (TRX#$id)";
 127                 if ( isset( $this->dbTrxHoldingLocks[$name] ) ) {
 128                         wfDebugLog( 'DBPerformance', "Nested transaction for '$name' - out of sync." );
 129                 }
 130                 $this->dbTrxHoldingLocks[$name] = array(
 131                         'start' => microtime( true ),
 132                         'conns' => array(), // all connections involved
 133                 );
 134                 $this->dbTrxMethodTimes[$name] = array();
 135
 136                 foreach ( $this->dbTrxHoldingLocks as $name => &$info ) {
 137                         // Track all DBs in transactions for this transaction
 138                         $info['conns'][$name] = 1;
 139                 }
 140         }
 141
 142         /**
 143          * Register the name and time of a method for slow DB trx detection
 144          *
 145          * This assumes that all queries are synchronous (non-overlapping)
 146          *
 147          * @param string $query Function name or generalized SQL
 148          * @param float $sTime Starting UNIX wall time
 149          * @param bool $isWrite Whether this is a write query
 150          * @param integer $n Number of affected rows
 151          */
 152         public function recordQueryCompletion( $query, $sTime, $isWrite = false, $n = 0 ) {
 153                 $eTime = microtime( true );
 154                 $elapsed = ( $eTime - $sTime );
 155
 156                 if ( $isWrite && $n > $this->expect['maxAffected'] ) {
 157                         wfDebugLog( 'DBPerformance',
 158                                 "Query affected $n row(s):\n" . $query . "\n" . wfBacktrace( true ) );
 159                 }
 160
 161                 // Report when too many writes/queries happen...
 162                 if ( $this->hits['queries']++ == $this->expect['queries'] ) {
 163                         $this->reportExpectationViolated( 'queries', $query );
 164                 }
 165                 if ( $isWrite && $this->hits['writes']++ == $this->expect['writes'] ) {
 166                         $this->reportExpectationViolated( 'writes', $query );
 167                 }
 168
 169                 if ( !$this->dbTrxHoldingLocks ) {
 170                         // Short-circuit
 171                         return;
 172                 } elseif ( !$isWrite && $elapsed < $this->eventThreshold ) {
 173                         // Not an important query nor slow enough
 174                         return;
 175                 }
 176
 177                 foreach ( $this->dbTrxHoldingLocks as $name => $info ) {
 178                         $lastQuery = end( $this->dbTrxMethodTimes[$name] );
 179                         if ( $lastQuery ) {
 180                                 // Additional query in the trx...
 181                                 $lastEnd = $lastQuery[2];
 182                                 if ( $sTime >= $lastEnd ) { // sanity check
 183                                         if ( ( $sTime - $lastEnd ) > $this->eventThreshold ) {
 184                                                 // Add an entry representing the time spent doing non-queries
 185                                                 $this->dbTrxMethodTimes[$name][] = array( '...delay...', $lastEnd, $sTime );
 186                                         }
 187                                         $this->dbTrxMethodTimes[$name][] = array( $query, $sTime, $eTime );
 188                                 }
 189                         } else {
 190                                 // First query in the trx...
 191                                 if ( $sTime >= $info['start'] ) { // sanity check
 192                                         $this->dbTrxMethodTimes[$name][] = array( $query, $sTime, $eTime );
 193                                 }
 194                         }
 195                 }
 196         }
 197
 198         /**
 199          * Mark a DB as no longer in a transaction
 200          *
 201          * This will check if locks are possibly held for longer than
 202          * needed and log any affected transactions to a special DB log.
 203          * Note that there can be multiple connections to a single DB.
 204          *
 205          * @param string $server DB server
 206          * @param string $db DB name
 207          * @param string $id ID string of transaction
 208          */
 209         public function transactionWritingOut( $server, $db, $id ) {
 210                 $name = "{$server} ({$db}) (TRX#$id)";
 211                 if ( !isset( $this->dbTrxMethodTimes[$name] ) ) {
 212                         wfDebugLog( 'DBPerformance', "Detected no transaction for '$name' - out of sync." );
 213                         return;
 214                 }
 215                 // Fill in the last non-query period...
 216                 $lastQuery = end( $this->dbTrxMethodTimes[$name] );
 217                 if ( $lastQuery ) {
 218                         $now = microtime( true );
 219                         $lastEnd = $lastQuery[2];
 220                         if ( ( $now - $lastEnd ) > $this->eventThreshold ) {
 221                                 $this->dbTrxMethodTimes[$name][] = array( '...delay...', $lastEnd, $now );
 222                         }
 223                 }
 224                 // Check for any slow queries or non-query periods...
 225                 $slow = false;
 226                 foreach ( $this->dbTrxMethodTimes[$name] as $info ) {
 227                         $elapsed = ( $info[2] - $info[1] );
 228                         if ( $elapsed >= $this->dbLockThreshold ) {
 229                                 $slow = true;
 230                                 break;
 231                         }
 232                 }
 233                 if ( $slow ) {
 234                         $dbs = implode( ', ', array_keys( $this->dbTrxHoldingLocks[$name]['conns'] ) );
 235                         $msg = "Sub-optimal transaction on DB(s) [{$dbs}]:\n";
 236                         foreach ( $this->dbTrxMethodTimes[$name] as $i => $info ) {
 237                                 list( $query, $sTime, $end ) = $info;
 238                                 $msg .= sprintf( "%d\t%.6f\t%s\n", $i, ( $end - $sTime ), $query );
 239                         }
 240                         wfDebugLog( 'DBPerformance', $msg );
 241                 }
 242                 unset( $this->dbTrxHoldingLocks[$name] );
 243                 unset( $this->dbTrxMethodTimes[$name] );
 244         }
 245
 246         /**
 247          * @param string $expect
 248          * @param string $query
 249          */
 250         protected function reportExpectationViolated( $expect, $query ) {
 251                 $n = $this->expect[$expect];
 252                 $by = $this->expectBy[$expect];
 253                 wfDebugLog( 'DBPerformance',
 254                         "Expectation ($expect <= $n) by $by not met:\n$query\n" . wfBacktrace( true ) );
 255         }
 256 }