includes/jobqueue/JobRunner.php

   1 <?php
   2 /**
   3  * Job queue runner utility methods
   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 JobQueue
  22  */
  23
  24 /**
  25  * Job queue runner utility methods
  26  *
  27  * @ingroup JobQueue
  28  * @since 1.24
  29  */
  30 class JobRunner {
  31         /** @var callable|null Debug output handler */
  32         protected $debug;
  33
  34         /**
  35          * @param callable $debug Optional debug output handler
  36          */
  37         public function setDebugHandler( $debug ) {
  38                 $this->debug = $debug;
  39         }
  40
  41         /**
  42          * Run jobs of the specified number/type for the specified time
  43          *
  44          * The response map has a 'job' field that lists status of each job, including:
  45          *   - type   : the job type
  46          *   - status : ok/failed
  47          *   - error  : any error message string
  48          *   - time   : the job run time in ms
  49          * The response map also has:
  50          *   - backoffs : the (job type => seconds) map of backoff times
  51          *   - elapsed  : the total time spent running tasks in ms
  52          *   - reached  : the reason the script finished, one of (none-ready, job-limit, time-limit)
  53          *
  54          * This method outputs status information only if a debug handler was set.
  55          * Any exceptions are caught and logged, but are not reported as output.
  56          *
  57          * @param array $options Map of parameters:
  58          *    - type     : the job type (or false for the default types)
  59          *    - maxJobs  : maximum number of jobs to run
  60          *    - maxTime  : maximum time in seconds before stopping
  61          *    - throttle : whether to respect job backoff configuration
  62          * @return array Summary response that can easily be JSON serialized
  63          */
  64         public function run( array $options ) {
  65                 $response = array( 'jobs' => array(), 'reached' => 'none-ready' );
  66
  67                 $type = isset( $options['type'] ) ? $options['type'] : false;
  68                 $maxJobs = isset( $options['maxJobs'] ) ? $options['maxJobs'] : false;
  69                 $maxTime = isset( $options['maxTime'] ) ? $options['maxTime'] : false;
  70                 $noThrottle = isset( $options['throttle'] ) && !$options['throttle'];
  71
  72                 $group = JobQueueGroup::singleton();
  73                 // Handle any required periodic queue maintenance
  74                 $count = $group->executeReadyPeriodicTasks();
  75                 if ( $count > 0 ) {
  76                         $this->runJobsLog( "Executed $count periodic queue task(s)." );
  77                 }
  78
  79                 // Flush any pending DB writes for sanity
  80                 wfGetLBFactory()->commitMasterChanges();
  81
  82                 // Some jobs types should not run until a certain timestamp
  83                 $backoffs = $this->loadBackoffs( array(), 'wait' ); // map of (type => UNIX expiry)
  84                 $backoffDeltas = array(); // map of (type => seconds)
  85                 $backoffExpireFunc = function ( $t ) {
  86                         return $t > time();
  87                 };
  88
  89                 $jobsRun = 0; // counter
  90                 $timeMsTotal = 0;
  91                 $flags = JobQueueGroup::USE_CACHE;
  92                 $sTime = microtime( true ); // time since jobs started running
  93                 $lastTime = microtime( true ); // time since last slave check
  94                 do {
  95                         $backoffs = array_filter( $backoffs, $backoffExpireFunc );
  96                         $blacklist = $noThrottle ? array() : array_keys( $backoffs );
  97                         if ( $type === false ) {
  98                                 $job = $group->pop( JobQueueGroup::TYPE_DEFAULT, $flags, $blacklist );
  99                         } elseif ( in_array( $type, $blacklist ) ) {
 100                                 $job = false; // requested queue in backoff state
 101                         } else {
 102                                 $job = $group->pop( $type ); // job from a single queue
 103                         }
 104                         if ( $job ) { // found a job
 105                                 $jType = $job->getType();
 106
 107                                 $this->runJobsLog( $job->toString() . " STARTING" );
 108
 109                                 // Run the job...
 110                                 wfProfileIn( __METHOD__ . '-' . get_class( $job ) );
 111                                 $sTime = microtime( true );
 112                                 try {
 113                                         ++$jobsRun;
 114                                         $status = $job->run();
 115                                         $error = $job->getLastError();
 116                                         wfGetLBFactory()->commitMasterChanges();
 117                                 } catch ( MWException $e ) {
 118                                         MWExceptionHandler::rollbackMasterChangesAndLog( $e );
 119                                         $status = false;
 120                                         $error = get_class( $e ) . ': ' . $e->getMessage();
 121                                         MWExceptionHandler::logException( $e );
 122                                 }
 123                                 $timeMs = intval( ( microtime( true ) - $sTime ) * 1000 );
 124                                 wfProfileOut( __METHOD__ . '-' . get_class( $job ) );
 125                                 $timeMsTotal += $timeMs;
 126
 127                                 // Mark the job as done on success or when the job cannot be retried
 128                                 if ( $status !== false || !$job->allowRetries() ) {
 129                                         $group->ack( $job ); // done
 130                                 }
 131
 132                                 // Back off of certain jobs for a while (for throttling and for errors)
 133                                 $ttw = $this->getBackoffTimeToWait( $job );
 134                                 if ( $status === false && mt_rand( 0, 49 ) == 0 ) {
 135                                         $ttw = max( $ttw, 30 ); // too many errors
 136                                 }
 137                                 if ( $ttw > 0 ) {
 138                                         // Always add the delta for other runners in case the time running the
 139                                         // job negated the backoff for each individually but not collectively.
 140                                         $backoffDeltas[$jType] = isset( $backoffDeltas[$jType] )
 141                                                 ? $backoffDeltas[$jType] + $ttw
 142                                                 : $ttw;
 143                                 }
 144
 145                                 // Sync the persistent backoffs with concurrent runners
 146                                 $backoffs = $backoffDeltas
 147                                         ? $this->syncBackoffDeltas( $backoffs, $backoffDeltas, 'nowait' )
 148                                         : $this->loadBackoffs( $backoffs, 'nowait' );
 149
 150                                 if ( $status === false ) {
 151                                         $this->runJobsLog( $job->toString() . " t=$timeMs error={$error}" );
 152                                 } else {
 153                                         $this->runJobsLog( $job->toString() . " t=$timeMs good" );
 154                                 }
 155
 156                                 $response['jobs'][] = array(
 157                                         'type'   => $jType,
 158                                         'status' => ( $status === false ) ? 'failed' : 'ok',
 159                                         'error'  => $error,
 160                                         'time'   => $timeMs
 161                                 );
 162
 163                                 // Break out if we hit the job count or wall time limits...
 164                                 if ( $maxJobs && $jobsRun >= $maxJobs ) {
 165                                         $response['reached'] = 'job-limit';
 166                                         break;
 167                                 } elseif ( $maxTime && ( microtime( true ) - $sTime ) > $maxTime ) {
 168                                         $response['reached'] = 'time-limit';
 169                                         break;
 170                                 }
 171
 172                                 // Don't let any of the main DB slaves get backed up
 173                                 $timePassed = microtime( true ) - $lastTime;
 174                                 if ( $timePassed >= 5 || $timePassed < 0 ) {
 175                                         wfWaitForSlaves( $lastTime );
 176                                         $lastTime = microtime( true );
 177                                 }
 178                                 // Don't let any queue slaves/backups fall behind
 179                                 if ( $jobsRun > 0 && ( $jobsRun % 100 ) == 0 ) {
 180                                         $group->waitForBackups();
 181                                 }
 182
 183                                 // Bail if near-OOM instead of in a job
 184                                 $this->assertMemoryOK();
 185                         }
 186                 } while ( $job ); // stop when there are no jobs
 187
 188                 // Sync the persistent backoffs for the next runJobs.php pass
 189                 if ( $backoffDeltas ) {
 190                         $this->syncBackoffDeltas( $backoffs, $backoffDeltas, 'wait' );
 191                 }
 192
 193                 $response['backoffs'] = $backoffs;
 194                 $response['elapsed'] = $timeMsTotal;
 195
 196                 return $response;
 197         }
 198
 199         /**
 200          * @param Job $job
 201          * @return int Seconds for this runner to avoid doing more jobs of this type
 202          * @see $wgJobBackoffThrottling
 203          */
 204         private function getBackoffTimeToWait( Job $job ) {
 205                 global $wgJobBackoffThrottling;
 206
 207                 if ( !isset( $wgJobBackoffThrottling[$job->getType()] ) ||
 208                         $job instanceof DuplicateJob // no work was done
 209                 ) {
 210                         return 0; // not throttled
 211                 }
 212
 213                 $itemsPerSecond = $wgJobBackoffThrottling[$job->getType()];
 214                 if ( $itemsPerSecond <= 0 ) {
 215                         return 0; // not throttled
 216                 }
 217
 218                 $seconds = 0;
 219                 if ( $job->workItemCount() > 0 ) {
 220                         $exactSeconds = $job->workItemCount() / $itemsPerSecond;
 221                         // use randomized rounding
 222                         $seconds = floor( $exactSeconds );
 223                         $remainder = $exactSeconds - $seconds;
 224                         $seconds += ( mt_rand() / mt_getrandmax() < $remainder ) ? 1 : 0;
 225                 }
 226
 227                 return (int)$seconds;
 228         }
 229
 230         /**
 231          * Get the previous backoff expiries from persistent storage
 232          * On I/O or lock acquisition failure this returns the original $backoffs.
 233          *
 234          * @param array $backoffs Map of (job type => UNIX timestamp)
 235          * @param string $mode Lock wait mode - "wait" or "nowait"
 236          * @return array Map of (job type => backoff expiry timestamp)
 237          */
 238         private function loadBackoffs( array $backoffs, $mode = 'wait' ) {
 239                 $section = new ProfileSection( __METHOD__ );
 240
 241                 $file = wfTempDir() . '/mw-runJobs-backoffs.json';
 242                 if ( is_file( $file ) ) {
 243                         $noblock = ( $mode === 'nowait' ) ? LOCK_NB : 0;
 244                         $handle = fopen( $file, 'rb' );
 245                         if ( !flock( $handle, LOCK_SH | $noblock ) ) {
 246                                 fclose( $handle );
 247                                 return $backoffs; // don't wait on lock
 248                         }
 249                         $content = stream_get_contents( $handle );
 250                         flock( $handle, LOCK_UN );
 251                         fclose( $handle );
 252                         $backoffs = json_decode( $content, true ) ?: array();
 253                 } else {
 254                         $backoffs = array();
 255                 }
 256
 257                 return $backoffs;
 258         }
 259
 260         /**
 261          * Merge the current backoff expiries from persistent storage
 262          *
 263          * The $deltas map is set to an empty array on success.
 264          * On I/O or lock acquisition failure this returns the original $backoffs.
 265          *
 266          * @param array $backoffs Map of (job type => UNIX timestamp)
 267          * @param array $deltas Map of (job type => seconds)
 268          * @param string $mode Lock wait mode - "wait" or "nowait"
 269          * @return array The new backoffs account for $backoffs and the latest file data
 270          */
 271         private function syncBackoffDeltas( array $backoffs, array &$deltas, $mode = 'wait' ) {
 272                 $section = new ProfileSection( __METHOD__ );
 273
 274                 $ctime = time();
 275                 $noblock = ( $mode === 'nowait' ) ? LOCK_NB : 0;
 276                 $file = wfTempDir() . '/mw-runJobs-backoffs.json';
 277                 $handle = fopen( $file, 'wb+' );
 278                 if ( !flock( $handle, LOCK_EX | $noblock ) ) {
 279                         fclose( $handle );
 280                         return $backoffs; // don't wait on lock
 281                 }
 282                 $content = stream_get_contents( $handle );
 283                 $cBackoffs = json_decode( $content, true ) ?: array();
 284                 foreach ( $deltas as $type => $seconds ) {
 285                         $cBackoffs[$type] = isset( $cBackoffs[$type] ) && $cBackoffs[$type] >= $ctime
 286                                 ? $cBackoffs[$type] + $seconds
 287                                 : $ctime + $seconds;
 288                 }
 289                 ftruncate( $handle, 0 );
 290                 fwrite( $handle, json_encode( $cBackoffs ) );
 291                 flock( $handle, LOCK_UN );
 292                 fclose( $handle );
 293
 294                 $deltas = array();
 295
 296                 return $cBackoffs;
 297         }
 298
 299         /**
 300          * Make sure that this script is not too close to the memory usage limit.
 301          * It is better to die in between jobs than OOM right in the middle of one.
 302          * @throws MWException
 303          */
 304         private function assertMemoryOK() {
 305                 static $maxBytes = null;
 306                 if ( $maxBytes === null ) {
 307                         $m = array();
 308                         if ( preg_match( '!^(\d+)(k|m|g|)$!i', ini_get( 'memory_limit' ), $m ) ) {
 309                                 list( , $num, $unit ) = $m;
 310                                 $conv = array( 'g' => 1073741824, 'm' => 1048576, 'k' => 1024, '' => 1 );
 311                                 $maxBytes = $num * $conv[strtolower( $unit )];
 312                         } else {
 313                                 $maxBytes = 0;
 314                         }
 315                 }
 316                 $usedBytes = memory_get_usage();
 317                 if ( $maxBytes && $usedBytes >= 0.95 * $maxBytes ) {
 318                         throw new MWException( "Detected excessive memory usage ($usedBytes/$maxBytes)." );
 319                 }
 320         }
 321
 322         /**
 323          * Log the job message
 324          * @param string $msg The message to log
 325          */
 326         private function runJobsLog( $msg ) {
 327                 if ( $this->debug ) {
 328                         call_user_func_array( $this->debug, array( wfTimestamp( TS_DB ) . " $msg\n" ) );
 329                 }
 330                 wfDebugLog( 'runJobs', $msg );
 331         }
 332 }