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 use MediaWiki\MediaWikiServices;
  25 use MediaWiki\Logger\LoggerFactory;
  26 use Liuggio\StatsdClient\Factory\StatsdDataFactory;
  27 use Psr\Log\LoggerAwareInterface;
  28 use Psr\Log\LoggerInterface;
  29 use Wikimedia\ScopedCallback;
  30 use Wikimedia\Rdbms\LBFactory;
  31 use Wikimedia\Rdbms\DBError;
  32 use Wikimedia\Rdbms\DBReplicationWaitError;
  33
  34 /**
  35  * Job queue runner utility methods
  36  *
  37  * @ingroup JobQueue
  38  * @since 1.24
  39  */
  40 class JobRunner implements LoggerAwareInterface {
  41         /** @var Config */
  42         protected $config;
  43         /** @var callable|null Debug output handler */
  44         protected $debug;
  45
  46         /**
  47          * @var LoggerInterface $logger
  48          */
  49         protected $logger;
  50
  51         const MAX_ALLOWED_LAG = 3; // abort if more than this much DB lag is present
  52         const LAG_CHECK_PERIOD = 1.0; // check replica DB lag this many seconds
  53         const ERROR_BACKOFF_TTL = 1; // seconds to back off a queue due to errors
  54         const READONLY_BACKOFF_TTL = 30; // seconds to back off a queue due to read-only errors
  55
  56         /**
  57          * @param callable $debug Optional debug output handler
  58          */
  59         public function setDebugHandler( $debug ) {
  60                 $this->debug = $debug;
  61         }
  62
  63         /**
  64          * @param LoggerInterface $logger
  65          * @return void
  66          */
  67         public function setLogger( LoggerInterface $logger ) {
  68                 $this->logger = $logger;
  69         }
  70
  71         /**
  72          * @param LoggerInterface $logger
  73          */
  74         public function __construct( LoggerInterface $logger = null ) {
  75                 if ( $logger === null ) {
  76                         $logger = LoggerFactory::getInstance( 'runJobs' );
  77                 }
  78                 $this->setLogger( $logger );
  79                 $this->config = MediaWikiServices::getInstance()->getMainConfig();
  80         }
  81
  82         /**
  83          * Run jobs of the specified number/type for the specified time
  84          *
  85          * The response map has a 'job' field that lists status of each job, including:
  86          *   - type   : the job type
  87          *   - status : ok/failed
  88          *   - error  : any error message string
  89          *   - time   : the job run time in ms
  90          * The response map also has:
  91          *   - backoffs : the (job type => seconds) map of backoff times
  92          *   - elapsed  : the total time spent running tasks in ms
  93          *   - reached  : the reason the script finished, one of (none-ready, job-limit, time-limit,
  94          *  memory-limit)
  95          *
  96          * This method outputs status information only if a debug handler was set.
  97          * Any exceptions are caught and logged, but are not reported as output.
  98          *
  99          * @param array $options Map of parameters:
 100          *    - type     : the job type (or false for the default types)
 101          *    - maxJobs  : maximum number of jobs to run
 102          *    - maxTime  : maximum time in seconds before stopping
 103          *    - throttle : whether to respect job backoff configuration
 104          * @return array Summary response that can easily be JSON serialized
 105          */
 106         public function run( array $options ) {
 107                 $jobClasses = $this->config->get( 'JobClasses' );
 108                 $profilerLimits = $this->config->get( 'TrxProfilerLimits' );
 109
 110                 $response = [ 'jobs' => [], 'reached' => 'none-ready' ];
 111
 112                 $type = isset( $options['type'] ) ? $options['type'] : false;
 113                 $maxJobs = isset( $options['maxJobs'] ) ? $options['maxJobs'] : false;
 114                 $maxTime = isset( $options['maxTime'] ) ? $options['maxTime'] : false;
 115                 $noThrottle = isset( $options['throttle'] ) && !$options['throttle'];
 116
 117                 // Bail if job type is invalid
 118                 if ( $type !== false && !isset( $jobClasses[$type] ) ) {
 119                         $response['reached'] = 'none-possible';
 120                         return $response;
 121                 }
 122
 123                 // Bail out if DB is in read-only mode
 124                 if ( wfReadOnly() ) {
 125                         $response['reached'] = 'read-only';
 126                         return $response;
 127                 }
 128
 129                 $lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
 130                 if ( $lbFactory->hasTransactionRound() ) {
 131                         throw new LogicException( __METHOD__ . ' called with an active transaction round.' );
 132                 }
 133                 // Bail out if there is too much DB lag.
 134                 // This check should not block as we want to try other wiki queues.
 135                 list( , $maxLag ) = $lbFactory->getMainLB( wfWikiID() )->getMaxLag();
 136                 if ( $maxLag >= self::MAX_ALLOWED_LAG ) {
 137                         $response['reached'] = 'replica-lag-limit';
 138                         return $response;
 139                 }
 140
 141                 // Catch huge single updates that lead to replica DB lag
 142                 $trxProfiler = Profiler::instance()->getTransactionProfiler();
 143                 $trxProfiler->setLogger( LoggerFactory::getInstance( 'DBPerformance' ) );
 144                 $trxProfiler->setExpectations( $profilerLimits['JobRunner'], __METHOD__ );
 145
 146                 // Some jobs types should not run until a certain timestamp
 147                 $backoffs = []; // map of (type => UNIX expiry)
 148                 $backoffDeltas = []; // map of (type => seconds)
 149                 $wait = 'wait'; // block to read backoffs the first time
 150
 151                 $group = JobQueueGroup::singleton();
 152                 $stats = MediaWikiServices::getInstance()->getStatsdDataFactory();
 153                 $jobsPopped = 0;
 154                 $timeMsTotal = 0;
 155                 $startTime = microtime( true ); // time since jobs started running
 156                 $lastCheckTime = 1; // timestamp of last replica DB check
 157                 do {
 158                         // Sync the persistent backoffs with concurrent runners
 159                         $backoffs = $this->syncBackoffDeltas( $backoffs, $backoffDeltas, $wait );
 160                         $blacklist = $noThrottle ? [] : array_keys( $backoffs );
 161                         $wait = 'nowait'; // less important now
 162
 163                         if ( $type === false ) {
 164                                 $job = $group->pop(
 165                                         JobQueueGroup::TYPE_DEFAULT,
 166                                         JobQueueGroup::USE_CACHE,
 167                                         $blacklist
 168                                 );
 169                         } elseif ( in_array( $type, $blacklist ) ) {
 170                                 $job = false; // requested queue in backoff state
 171                         } else {
 172                                 $job = $group->pop( $type ); // job from a single queue
 173                         }
 174
 175                         if ( $job ) { // found a job
 176                                 ++$jobsPopped;
 177                                 $popTime = time();
 178                                 $jType = $job->getType();
 179
 180                                 WebRequest::overrideRequestId( $job->getRequestId() );
 181
 182                                 // Back off of certain jobs for a while (for throttling and for errors)
 183                                 $ttw = $this->getBackoffTimeToWait( $job );
 184                                 if ( $ttw > 0 ) {
 185                                         // Always add the delta for other runners in case the time running the
 186                                         // job negated the backoff for each individually but not collectively.
 187                                         $backoffDeltas[$jType] = isset( $backoffDeltas[$jType] )
 188                                                 ? $backoffDeltas[$jType] + $ttw
 189                                                 : $ttw;
 190                                         $backoffs = $this->syncBackoffDeltas( $backoffs, $backoffDeltas, $wait );
 191                                 }
 192
 193                                 $info = $this->executeJob( $job, $lbFactory, $stats, $popTime );
 194                                 if ( $info['status'] !== false || !$job->allowRetries() ) {
 195                                         $group->ack( $job ); // succeeded or job cannot be retried
 196                                 }
 197
 198                                 // Back off of certain jobs for a while (for throttling and for errors)
 199                                 if ( $info['status'] === false && mt_rand( 0, 49 ) == 0 ) {
 200                                         $ttw = max( $ttw, $this->getErrorBackoffTTL( $info['error'] ) );
 201                                         $backoffDeltas[$jType] = isset( $backoffDeltas[$jType] )
 202                                                 ? $backoffDeltas[$jType] + $ttw
 203                                                 : $ttw;
 204                                 }
 205
 206                                 $response['jobs'][] = [
 207                                         'type'   => $jType,
 208                                         'status' => ( $info['status'] === false ) ? 'failed' : 'ok',
 209                                         'error'  => $info['error'],
 210                                         'time'   => $info['timeMs']
 211                                 ];
 212                                 $timeMsTotal += $info['timeMs'];
 213
 214                                 // Break out if we hit the job count or wall time limits...
 215                                 if ( $maxJobs && $jobsPopped >= $maxJobs ) {
 216                                         $response['reached'] = 'job-limit';
 217                                         break;
 218                                 } elseif ( $maxTime && ( microtime( true ) - $startTime ) > $maxTime ) {
 219                                         $response['reached'] = 'time-limit';
 220                                         break;
 221                                 }
 222
 223                                 // Don't let any of the main DB replica DBs get backed up.
 224                                 // This only waits for so long before exiting and letting
 225                                 // other wikis in the farm (on different masters) get a chance.
 226                                 $timePassed = microtime( true ) - $lastCheckTime;
 227                                 if ( $timePassed >= self::LAG_CHECK_PERIOD || $timePassed < 0 ) {
 228                                         try {
 229                                                 $lbFactory->waitForReplication( [
 230                                                         'ifWritesSince' => $lastCheckTime,
 231                                                         'timeout' => self::MAX_ALLOWED_LAG
 232                                                 ] );
 233                                         } catch ( DBReplicationWaitError $e ) {
 234                                                 $response['reached'] = 'replica-lag-limit';
 235                                                 break;
 236                                         }
 237                                         $lastCheckTime = microtime( true );
 238                                 }
 239                                 // Don't let any queue replica DBs/backups fall behind
 240                                 if ( $jobsPopped > 0 && ( $jobsPopped % 100 ) == 0 ) {
 241                                         $group->waitForBackups();
 242                                 }
 243
 244                                 // Bail if near-OOM instead of in a job
 245                                 if ( !$this->checkMemoryOK() ) {
 246                                         $response['reached'] = 'memory-limit';
 247                                         break;
 248                                 }
 249                         }
 250                 } while ( $job ); // stop when there are no jobs
 251
 252                 // Sync the persistent backoffs for the next runJobs.php pass
 253                 if ( $backoffDeltas ) {
 254                         $this->syncBackoffDeltas( $backoffs, $backoffDeltas, 'wait' );
 255                 }
 256
 257                 $response['backoffs'] = $backoffs;
 258                 $response['elapsed'] = $timeMsTotal;
 259
 260                 return $response;
 261         }
 262
 263         /**
 264          * @param string $error
 265          * @return int TTL in seconds
 266          */
 267         private function getErrorBackoffTTL( $error ) {
 268                 return strpos( $error, 'DBReadOnlyError' ) !== false
 269                         ? self::READONLY_BACKOFF_TTL
 270                         : self::ERROR_BACKOFF_TTL;
 271         }
 272
 273         /**
 274          * @param Job $job
 275          * @param LBFactory $lbFactory
 276          * @param StatsdDataFactory $stats
 277          * @param float $popTime
 278          * @return array Map of status/error/timeMs
 279          */
 280         private function executeJob( Job $job, LBFactory $lbFactory, $stats, $popTime ) {
 281                 $jType = $job->getType();
 282                 $msg = $job->toString() . " STARTING";
 283                 $this->logger->debug( $msg, [
 284                         'job_type' => $job->getType(),
 285                 ] );
 286                 $this->debugCallback( $msg );
 287
 288                 // Run the job...
 289                 $rssStart = $this->getMaxRssKb();
 290                 $jobStartTime = microtime( true );
 291                 try {
 292                         $fnameTrxOwner = get_class( $job ) . '::run'; // give run() outer scope
 293                         if ( !$job->hasExecutionFlag( $job::JOB_NO_EXPLICIT_TRX_ROUND ) ) {
 294                                 $lbFactory->beginMasterChanges( $fnameTrxOwner );
 295                         }
 296                         $status = $job->run();
 297                         $error = $job->getLastError();
 298                         $this->commitMasterChanges( $lbFactory, $job, $fnameTrxOwner );
 299                         // Important: this must be the last deferred update added (T100085, T154425)
 300                         DeferredUpdates::addCallableUpdate( [ JobQueueGroup::class, 'pushLazyJobs' ] );
 301                         // Run any deferred update tasks; doUpdates() manages transactions itself
 302                         DeferredUpdates::doUpdates();
 303                 } catch ( Exception $e ) {
 304                         MWExceptionHandler::rollbackMasterChangesAndLog( $e );
 305                         $status = false;
 306                         $error = get_class( $e ) . ': ' . $e->getMessage();
 307                 }
 308                 // Always attempt to call teardown() even if Job throws exception.
 309                 try {
 310                         $job->teardown( $status );
 311                 } catch ( Exception $e ) {
 312                         MWExceptionHandler::logException( $e );
 313                 }
 314
 315                 // Commit all outstanding connections that are in a transaction
 316                 // to get a fresh repeatable read snapshot on every connection.
 317                 // Note that jobs are still responsible for handling replica DB lag.
 318                 $lbFactory->flushReplicaSnapshots( __METHOD__ );
 319                 // Clear out title cache data from prior snapshots
 320                 MediaWikiServices::getInstance()->getLinkCache()->clear();
 321                 $timeMs = intval( ( microtime( true ) - $jobStartTime ) * 1000 );
 322                 $rssEnd = $this->getMaxRssKb();
 323
 324                 // Record how long jobs wait before getting popped
 325                 $readyTs = $job->getReadyTimestamp();
 326                 if ( $readyTs ) {
 327                         $pickupDelay = max( 0, $popTime - $readyTs );
 328                         $stats->timing( 'jobqueue.pickup_delay.all', 1000 * $pickupDelay );
 329                         $stats->timing( "jobqueue.pickup_delay.$jType", 1000 * $pickupDelay );
 330                 }
 331                 // Record root job age for jobs being run
 332                 $rootTimestamp = $job->getRootJobParams()['rootJobTimestamp'];
 333                 if ( $rootTimestamp ) {
 334                         $age = max( 0, $popTime - wfTimestamp( TS_UNIX, $rootTimestamp ) );
 335                         $stats->timing( "jobqueue.pickup_root_age.$jType", 1000 * $age );
 336                 }
 337                 // Track the execution time for jobs
 338                 $stats->timing( "jobqueue.run.$jType", $timeMs );
 339                 // Track RSS increases for jobs (in case of memory leaks)
 340                 if ( $rssStart && $rssEnd ) {
 341                         $stats->updateCount( "jobqueue.rss_delta.$jType", $rssEnd - $rssStart );
 342                 }
 343
 344                 if ( $status === false ) {
 345                         $msg = $job->toString() . " t={job_duration} error={job_error}";
 346                         $this->logger->error( $msg, [
 347                                 'job_type' => $job->getType(),
 348                                 'job_duration' => $timeMs,
 349                                 'job_error' => $error,
 350                         ] );
 351
 352                         $msg = $job->toString() . " t=$timeMs error={$error}";
 353                         $this->debugCallback( $msg );
 354                 } else {
 355                         $msg = $job->toString() . " t={job_duration} good";
 356                         $this->logger->info( $msg, [
 357                                 'job_type' => $job->getType(),
 358                                 'job_duration' => $timeMs,
 359                         ] );
 360
 361                         $msg = $job->toString() . " t=$timeMs good";
 362                         $this->debugCallback( $msg );
 363                 }
 364
 365                 return [ 'status' => $status, 'error' => $error, 'timeMs' => $timeMs ];
 366         }
 367
 368         /**
 369          * @return int|null Max memory RSS in kilobytes
 370          */
 371         private function getMaxRssKb() {
 372                 $info = wfGetRusage() ?: [];
 373                 // see https://linux.die.net/man/2/getrusage
 374                 return isset( $info['ru_maxrss'] ) ? (int)$info['ru_maxrss'] : null;
 375         }
 376
 377         /**
 378          * @param Job $job
 379          * @return int Seconds for this runner to avoid doing more jobs of this type
 380          * @see $wgJobBackoffThrottling
 381          */
 382         private function getBackoffTimeToWait( Job $job ) {
 383                 $throttling = $this->config->get( 'JobBackoffThrottling' );
 384
 385                 if ( !isset( $throttling[$job->getType()] ) || $job instanceof DuplicateJob ) {
 386                         return 0; // not throttled
 387                 }
 388
 389                 $itemsPerSecond = $throttling[$job->getType()];
 390                 if ( $itemsPerSecond <= 0 ) {
 391                         return 0; // not throttled
 392                 }
 393
 394                 $seconds = 0;
 395                 if ( $job->workItemCount() > 0 ) {
 396                         $exactSeconds = $job->workItemCount() / $itemsPerSecond;
 397                         // use randomized rounding
 398                         $seconds = floor( $exactSeconds );
 399                         $remainder = $exactSeconds - $seconds;
 400                         $seconds += ( mt_rand() / mt_getrandmax() < $remainder ) ? 1 : 0;
 401                 }
 402
 403                 return (int)$seconds;
 404         }
 405
 406         /**
 407          * Get the previous backoff expiries from persistent storage
 408          * On I/O or lock acquisition failure this returns the original $backoffs.
 409          *
 410          * @param array $backoffs Map of (job type => UNIX timestamp)
 411          * @param string $mode Lock wait mode - "wait" or "nowait"
 412          * @return array Map of (job type => backoff expiry timestamp)
 413          */
 414         private function loadBackoffs( array $backoffs, $mode = 'wait' ) {
 415                 $file = wfTempDir() . '/mw-runJobs-backoffs.json';
 416                 if ( is_file( $file ) ) {
 417                         $noblock = ( $mode === 'nowait' ) ? LOCK_NB : 0;
 418                         $handle = fopen( $file, 'rb' );
 419                         if ( !flock( $handle, LOCK_SH | $noblock ) ) {
 420                                 fclose( $handle );
 421                                 return $backoffs; // don't wait on lock
 422                         }
 423                         $content = stream_get_contents( $handle );
 424                         flock( $handle, LOCK_UN );
 425                         fclose( $handle );
 426                         $ctime = microtime( true );
 427                         $cBackoffs = json_decode( $content, true ) ?: [];
 428                         foreach ( $cBackoffs as $type => $timestamp ) {
 429                                 if ( $timestamp < $ctime ) {
 430                                         unset( $cBackoffs[$type] );
 431                                 }
 432                         }
 433                 } else {
 434                         $cBackoffs = [];
 435                 }
 436
 437                 return $cBackoffs;
 438         }
 439
 440         /**
 441          * Merge the current backoff expiries from persistent storage
 442          *
 443          * The $deltas map is set to an empty array on success.
 444          * On I/O or lock acquisition failure this returns the original $backoffs.
 445          *
 446          * @param array $backoffs Map of (job type => UNIX timestamp)
 447          * @param array $deltas Map of (job type => seconds)
 448          * @param string $mode Lock wait mode - "wait" or "nowait"
 449          * @return array The new backoffs account for $backoffs and the latest file data
 450          */
 451         private function syncBackoffDeltas( array $backoffs, array &$deltas, $mode = 'wait' ) {
 452                 if ( !$deltas ) {
 453                         return $this->loadBackoffs( $backoffs, $mode );
 454                 }
 455
 456                 $noblock = ( $mode === 'nowait' ) ? LOCK_NB : 0;
 457                 $file = wfTempDir() . '/mw-runJobs-backoffs.json';
 458                 $handle = fopen( $file, 'wb+' );
 459                 if ( !flock( $handle, LOCK_EX | $noblock ) ) {
 460                         fclose( $handle );
 461                         return $backoffs; // don't wait on lock
 462                 }
 463                 $ctime = microtime( true );
 464                 $content = stream_get_contents( $handle );
 465                 $cBackoffs = json_decode( $content, true ) ?: [];
 466                 foreach ( $deltas as $type => $seconds ) {
 467                         $cBackoffs[$type] = isset( $cBackoffs[$type] ) && $cBackoffs[$type] >= $ctime
 468                                 ? $cBackoffs[$type] + $seconds
 469                                 : $ctime + $seconds;
 470                 }
 471                 foreach ( $cBackoffs as $type => $timestamp ) {
 472                         if ( $timestamp < $ctime ) {
 473                                 unset( $cBackoffs[$type] );
 474                         }
 475                 }
 476                 ftruncate( $handle, 0 );
 477                 fwrite( $handle, json_encode( $cBackoffs ) );
 478                 flock( $handle, LOCK_UN );
 479                 fclose( $handle );
 480
 481                 $deltas = [];
 482
 483                 return $cBackoffs;
 484         }
 485
 486         /**
 487          * Make sure that this script is not too close to the memory usage limit.
 488          * It is better to die in between jobs than OOM right in the middle of one.
 489          * @return bool
 490          */
 491         private function checkMemoryOK() {
 492                 static $maxBytes = null;
 493                 if ( $maxBytes === null ) {
 494                         $m = [];
 495                         if ( preg_match( '!^(\d+)(k|m|g|)$!i', ini_get( 'memory_limit' ), $m ) ) {
 496                                 list( , $num, $unit ) = $m;
 497                                 $conv = [ 'g' => 1073741824, 'm' => 1048576, 'k' => 1024, '' => 1 ];
 498                                 $maxBytes = $num * $conv[strtolower( $unit )];
 499                         } else {
 500                                 $maxBytes = 0;
 501                         }
 502                 }
 503                 $usedBytes = memory_get_usage();
 504                 if ( $maxBytes && $usedBytes >= 0.95 * $maxBytes ) {
 505                         $msg = "Detected excessive memory usage ({used_bytes}/{max_bytes}).";
 506                         $this->logger->error( $msg, [
 507                                 'used_bytes' => $usedBytes,
 508                                 'max_bytes' => $maxBytes,
 509                         ] );
 510
 511                         $msg = "Detected excessive memory usage ($usedBytes/$maxBytes).";
 512                         $this->debugCallback( $msg );
 513
 514                         return false;
 515                 }
 516
 517                 return true;
 518         }
 519
 520         /**
 521          * Log the job message
 522          * @param string $msg The message to log
 523          */
 524         private function debugCallback( $msg ) {
 525                 if ( $this->debug ) {
 526                         call_user_func_array( $this->debug, [ wfTimestamp( TS_DB ) . " $msg\n" ] );
 527                 }
 528         }
 529
 530         /**
 531          * Issue a commit on all masters who are currently in a transaction and have
 532          * made changes to the database. It also supports sometimes waiting for the
 533          * local wiki's replica DBs to catch up. See the documentation for
 534          * $wgJobSerialCommitThreshold for more.
 535          *
 536          * @param LBFactory $lbFactory
 537          * @param Job $job
 538          * @param string $fnameTrxOwner
 539          * @throws DBError
 540          */
 541         private function commitMasterChanges( LBFactory $lbFactory, Job $job, $fnameTrxOwner ) {
 542                 $syncThreshold = $this->config->get( 'JobSerialCommitThreshold' );
 543
 544                 $time = false;
 545                 $lb = $lbFactory->getMainLB( wfWikiID() );
 546                 if ( $syncThreshold !== false && $lb->getServerCount() > 1 ) {
 547                         // Generally, there is one master connection to the local DB
 548                         $dbwSerial = $lb->getAnyOpenConnection( $lb->getWriterIndex() );
 549                         // We need natively blocking fast locks
 550                         if ( $dbwSerial && $dbwSerial->namedLocksEnqueue() ) {
 551                                 $time = $dbwSerial->pendingWriteQueryDuration( $dbwSerial::ESTIMATE_DB_APPLY );
 552                                 if ( $time < $syncThreshold ) {
 553                                         $dbwSerial = false;
 554                                 }
 555                         } else {
 556                                 $dbwSerial = false;
 557                         }
 558                 } else {
 559                         // There are no replica DBs or writes are all to foreign DB (we don't handle that)
 560                         $dbwSerial = false;
 561                 }
 562
 563                 if ( !$dbwSerial ) {
 564                         $lbFactory->commitMasterChanges(
 565                                 $fnameTrxOwner,
 566                                 // Abort if any transaction was too big
 567                                 [ 'maxWriteDuration' => $this->config->get( 'MaxJobDBWriteDuration' ) ]
 568                         );
 569
 570                         return;
 571                 }
 572
 573                 $ms = intval( 1000 * $time );
 574
 575                 $msg = $job->toString() . " COMMIT ENQUEUED [{job_commit_write_ms}ms of writes]";
 576                 $this->logger->info( $msg, [
 577                         'job_type' => $job->getType(),
 578                         'job_commit_write_ms' => $ms,
 579                 ] );
 580
 581                 $msg = $job->toString() . " COMMIT ENQUEUED [{$ms}ms of writes]";
 582                 $this->debugCallback( $msg );
 583
 584                 // Wait for an exclusive lock to commit
 585                 if ( !$dbwSerial->lock( 'jobrunner-serial-commit', __METHOD__, 30 ) ) {
 586                         // This will trigger a rollback in the main loop
 587                         throw new DBError( $dbwSerial, "Timed out waiting on commit queue." );
 588                 }
 589                 $unlocker = new ScopedCallback( function () use ( $dbwSerial ) {
 590                         $dbwSerial->unlock( 'jobrunner-serial-commit', __METHOD__ );
 591                 } );
 592
 593                 // Wait for the replica DBs to catch up
 594                 $pos = $lb->getMasterPos();
 595                 if ( $pos ) {
 596                         $lb->waitForAll( $pos );
 597                 }
 598
 599                 // Actually commit the DB master changes
 600                 $lbFactory->commitMasterChanges(
 601                         $fnameTrxOwner,
 602                         // Abort if any transaction was too big
 603                         [ 'maxWriteDuration' => $this->config->get( 'MaxJobDBWriteDuration' ) ]
 604                 );
 605                 ScopedCallback::consume( $unlocker );
 606         }
 607 }