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\Logger\LoggerFactory;
  25 use Psr\Log\LoggerAwareInterface;
  26 use Psr\Log\LoggerInterface;
  27
  28 /**
  29  * Job queue runner utility methods
  30  *
  31  * @ingroup JobQueue
  32  * @since 1.24
  33  */
  34 class JobRunner implements LoggerAwareInterface {
  35         /** @var callable|null Debug output handler */
  36         protected $debug;
  37
  38         /**
  39          * @var LoggerInterface $logger
  40          */
  41         protected $logger;
  42
  43         /**
  44          * @param callable $debug Optional debug output handler
  45          */
  46         public function setDebugHandler( $debug ) {
  47                 $this->debug = $debug;
  48         }
  49
  50         /**
  51          * @param LoggerInterface $logger
  52          * @return void
  53          */
  54         public function setLogger( LoggerInterface $logger ) {
  55                 $this->logger = $logger;
  56         }
  57
  58         /**
  59          * @param LoggerInterface $logger
  60          */
  61         public function __construct( LoggerInterface $logger = null ) {
  62                 if ( $logger === null ) {
  63                         $logger = LoggerFactory::getInstance( 'runJobs' );
  64                 }
  65                 $this->setLogger( $logger );
  66         }
  67
  68         /**
  69          * Run jobs of the specified number/type for the specified time
  70          *
  71          * The response map has a 'job' field that lists status of each job, including:
  72          *   - type   : the job type
  73          *   - status : ok/failed
  74          *   - error  : any error message string
  75          *   - time   : the job run time in ms
  76          * The response map also has:
  77          *   - backoffs : the (job type => seconds) map of backoff times
  78          *   - elapsed  : the total time spent running tasks in ms
  79          *   - reached  : the reason the script finished, one of (none-ready, job-limit, time-limit)
  80          *
  81          * This method outputs status information only if a debug handler was set.
  82          * Any exceptions are caught and logged, but are not reported as output.
  83          *
  84          * @param array $options Map of parameters:
  85          *    - type     : the job type (or false for the default types)
  86          *    - maxJobs  : maximum number of jobs to run
  87          *    - maxTime  : maximum time in seconds before stopping
  88          *    - throttle : whether to respect job backoff configuration
  89          * @return array Summary response that can easily be JSON serialized
  90          */
  91         public function run( array $options ) {
  92                 global $wgJobClasses, $wgTrxProfilerLimits;
  93
  94                 $response = array( 'jobs' => array(), 'reached' => 'none-ready' );
  95
  96                 $type = isset( $options['type'] ) ? $options['type'] : false;
  97                 $maxJobs = isset( $options['maxJobs'] ) ? $options['maxJobs'] : false;
  98                 $maxTime = isset( $options['maxTime'] ) ? $options['maxTime'] : false;
  99                 $noThrottle = isset( $options['throttle'] ) && !$options['throttle'];
 100
 101                 if ( $type !== false && !isset( $wgJobClasses[$type] ) ) {
 102                         $response['reached'] = 'none-possible';
 103                         return $response;
 104                 }
 105
 106                 // Bail out if in read-only mode
 107                 if ( wfReadOnly() ) {
 108                         $response['reached'] = 'read-only';
 109                         return $response;
 110                 }
 111
 112                 $profiler = Profiler::instance();
 113
 114                 // Catch huge single updates that lead to slave lag
 115                 $trxProfiler = $profiler->getTransactionProfiler();
 116                 $trxProfiler->setLogger( LoggerFactory::getInstance( 'DBPerformance' ) );
 117                 $trxProfiler->setExpectations( $wgTrxProfilerLimits['JobRunner'], __METHOD__ );
 118
 119                 // Bail out if there is too much DB lag.
 120                 // This check should not block as we want to try other wiki queues.
 121                 $maxAllowedLag = 3;
 122                 list( , $maxLag ) = wfGetLB( wfWikiID() )->getMaxLag();
 123                 if ( $maxLag >= $maxAllowedLag ) {
 124                         $response['reached'] = 'slave-lag-limit';
 125                         return $response;
 126                 }
 127
 128                 $group = JobQueueGroup::singleton();
 129
 130                 // Flush any pending DB writes for sanity
 131                 wfGetLBFactory()->commitAll();
 132
 133                 // Some jobs types should not run until a certain timestamp
 134                 $backoffs = array(); // map of (type => UNIX expiry)
 135                 $backoffDeltas = array(); // map of (type => seconds)
 136                 $wait = 'wait'; // block to read backoffs the first time
 137
 138                 $jobsRun = 0;
 139                 $timeMsTotal = 0;
 140                 $flags = JobQueueGroup::USE_CACHE;
 141                 $startTime = microtime( true ); // time since jobs started running
 142                 $checkLagPeriod = 1.0; // check slave lag this many seconds
 143                 $lastCheckTime = 1; // timestamp of last slave check
 144                 do {
 145                         // Sync the persistent backoffs with concurrent runners
 146                         $backoffs = $this->syncBackoffDeltas( $backoffs, $backoffDeltas, $wait );
 147                         $blacklist = $noThrottle ? array() : array_keys( $backoffs );
 148                         $wait = 'nowait'; // less important now
 149
 150                         if ( $type === false ) {
 151                                 $job = $group->pop( JobQueueGroup::TYPE_DEFAULT, $flags, $blacklist );
 152                         } elseif ( in_array( $type, $blacklist ) ) {
 153                                 $job = false; // requested queue in backoff state
 154                         } else {
 155                                 $job = $group->pop( $type ); // job from a single queue
 156                         }
 157
 158                         if ( $job ) { // found a job
 159                                 $jType = $job->getType();
 160
 161                                 // Back off of certain jobs for a while (for throttling and for errors)
 162                                 $ttw = $this->getBackoffTimeToWait( $job );
 163                                 if ( $ttw > 0 ) {
 164                                         // Always add the delta for other runners in case the time running the
 165                                         // job negated the backoff for each individually but not collectively.
 166                                         $backoffDeltas[$jType] = isset( $backoffDeltas[$jType] )
 167                                                 ? $backoffDeltas[$jType] + $ttw
 168                                                 : $ttw;
 169                                         $backoffs = $this->syncBackoffDeltas( $backoffs, $backoffDeltas, $wait );
 170                                 }
 171
 172                                 $msg = $job->toString() . " STARTING";
 173                                 $this->logger->debug( $msg );
 174                                 $this->debugCallback( $msg );
 175
 176                                 // Run the job...
 177                                 $psection = $profiler->scopedProfileIn( __METHOD__ . '-' . $jType );
 178                                 $jobStartTime = microtime( true );
 179                                 try {
 180                                         ++$jobsRun;
 181                                         $status = $job->run();
 182                                         $error = $job->getLastError();
 183                                         $this->commitMasterChanges( $job );
 184
 185                                         DeferredUpdates::doUpdates();
 186                                         $this->commitMasterChanges( $job );
 187                                 } catch ( Exception $e ) {
 188                                         MWExceptionHandler::rollbackMasterChangesAndLog( $e );
 189                                         $status = false;
 190                                         $error = get_class( $e ) . ': ' . $e->getMessage();
 191                                         MWExceptionHandler::logException( $e );
 192                                 }
 193                                 // Commit all outstanding connections that are in a transaction
 194                                 // to get a fresh repeatable read snapshot on every connection.
 195                                 // This is important because if you have an old snapshot on the
 196                                 // database you could run the job incorrectly. Its possible, for
 197                                 // example, to pick up a RefreshLinksJob for a new page that isn't
 198                                 // even visible to the snapshot. The snapshot could have been
 199                                 // created before the page. Fresh snapshots will see the page.
 200                                 wfGetLBFactory()->commitAll();
 201                                 $timeMs = intval( ( microtime( true ) - $jobStartTime ) * 1000 );
 202                                 $timeMsTotal += $timeMs;
 203                                 $profiler->scopedProfileOut( $psection );
 204
 205                                 // Mark the job as done on success or when the job cannot be retried
 206                                 if ( $status !== false || !$job->allowRetries() ) {
 207                                         $group->ack( $job ); // done
 208                                 }
 209
 210                                 // Back off of certain jobs for a while (for throttling and for errors)
 211                                 if ( $status === false && mt_rand( 0, 49 ) == 0 ) {
 212                                         $ttw = max( $ttw, 30 ); // too many errors
 213                                         $backoffDeltas[$jType] = isset( $backoffDeltas[$jType] )
 214                                                 ? $backoffDeltas[$jType] + $ttw
 215                                                 : $ttw;
 216                                 }
 217
 218                                 if ( $status === false ) {
 219                                         $msg = $job->toString() . " t=$timeMs error={$error}";
 220                                         $this->logger->error( $msg );
 221                                         $this->debugCallback( $msg );
 222                                 } else {
 223                                         $msg = $job->toString() . " t=$timeMs good";
 224                                         $this->logger->info( $msg );
 225                                         $this->debugCallback( $msg );
 226                                 }
 227
 228                                 $response['jobs'][] = array(
 229                                         'type'   => $jType,
 230                                         'status' => ( $status === false ) ? 'failed' : 'ok',
 231                                         'error'  => $error,
 232                                         'time'   => $timeMs
 233                                 );
 234
 235                                 // Break out if we hit the job count or wall time limits...
 236                                 if ( $maxJobs && $jobsRun >= $maxJobs ) {
 237                                         $response['reached'] = 'job-limit';
 238                                         break;
 239                                 } elseif ( $maxTime && ( microtime( true ) - $startTime ) > $maxTime ) {
 240                                         $response['reached'] = 'time-limit';
 241                                         break;
 242                                 }
 243
 244                                 // Don't let any of the main DB slaves get backed up.
 245                                 // This only waits for so long before exiting and letting
 246                                 // other wikis in the farm (on different masters) get a chance.
 247                                 $timePassed = microtime( true ) - $lastCheckTime;
 248                                 if ( $timePassed >= $checkLagPeriod || $timePassed < 0 ) {
 249                                         if ( !wfWaitForSlaves( $lastCheckTime, false, '*', $maxAllowedLag ) ) {
 250                                                 $response['reached'] = 'slave-lag-limit';
 251                                                 break;
 252                                         }
 253                                         $lastCheckTime = microtime( true );
 254                                 }
 255                                 // Don't let any queue slaves/backups fall behind
 256                                 if ( $jobsRun > 0 && ( $jobsRun % 100 ) == 0 ) {
 257                                         $group->waitForBackups();
 258                                 }
 259
 260                                 // Bail if near-OOM instead of in a job
 261                                 $this->assertMemoryOK();
 262                         }
 263                 } while ( $job ); // stop when there are no jobs
 264
 265                 // Sync the persistent backoffs for the next runJobs.php pass
 266                 if ( $backoffDeltas ) {
 267                         $this->syncBackoffDeltas( $backoffs, $backoffDeltas, 'wait' );
 268                 }
 269
 270                 $response['backoffs'] = $backoffs;
 271                 $response['elapsed'] = $timeMsTotal;
 272
 273                 return $response;
 274         }
 275
 276         /**
 277          * @param Job $job
 278          * @return int Seconds for this runner to avoid doing more jobs of this type
 279          * @see $wgJobBackoffThrottling
 280          */
 281         private function getBackoffTimeToWait( Job $job ) {
 282                 global $wgJobBackoffThrottling;
 283
 284                 if ( !isset( $wgJobBackoffThrottling[$job->getType()] ) ||
 285                         $job instanceof DuplicateJob // no work was done
 286                 ) {
 287                         return 0; // not throttled
 288                 }
 289
 290                 $itemsPerSecond = $wgJobBackoffThrottling[$job->getType()];
 291                 if ( $itemsPerSecond <= 0 ) {
 292                         return 0; // not throttled
 293                 }
 294
 295                 $seconds = 0;
 296                 if ( $job->workItemCount() > 0 ) {
 297                         $exactSeconds = $job->workItemCount() / $itemsPerSecond;
 298                         // use randomized rounding
 299                         $seconds = floor( $exactSeconds );
 300                         $remainder = $exactSeconds - $seconds;
 301                         $seconds += ( mt_rand() / mt_getrandmax() < $remainder ) ? 1 : 0;
 302                 }
 303
 304                 return (int)$seconds;
 305         }
 306
 307         /**
 308          * Get the previous backoff expiries from persistent storage
 309          * On I/O or lock acquisition failure this returns the original $backoffs.
 310          *
 311          * @param array $backoffs Map of (job type => UNIX timestamp)
 312          * @param string $mode Lock wait mode - "wait" or "nowait"
 313          * @return array Map of (job type => backoff expiry timestamp)
 314          */
 315         private function loadBackoffs( array $backoffs, $mode = 'wait' ) {
 316                 $file = wfTempDir() . '/mw-runJobs-backoffs.json';
 317                 if ( is_file( $file ) ) {
 318                         $noblock = ( $mode === 'nowait' ) ? LOCK_NB : 0;
 319                         $handle = fopen( $file, 'rb' );
 320                         if ( !flock( $handle, LOCK_SH | $noblock ) ) {
 321                                 fclose( $handle );
 322                                 return $backoffs; // don't wait on lock
 323                         }
 324                         $content = stream_get_contents( $handle );
 325                         flock( $handle, LOCK_UN );
 326                         fclose( $handle );
 327                         $ctime = microtime( true );
 328                         $cBackoffs = json_decode( $content, true ) ?: array();
 329                         foreach ( $cBackoffs as $type => $timestamp ) {
 330                                 if ( $timestamp < $ctime ) {
 331                                         unset( $cBackoffs[$type] );
 332                                 }
 333                         }
 334                 } else {
 335                         $cBackoffs = array();
 336                 }
 337
 338                 return $cBackoffs;
 339         }
 340
 341         /**
 342          * Merge the current backoff expiries from persistent storage
 343          *
 344          * The $deltas map is set to an empty array on success.
 345          * On I/O or lock acquisition failure this returns the original $backoffs.
 346          *
 347          * @param array $backoffs Map of (job type => UNIX timestamp)
 348          * @param array $deltas Map of (job type => seconds)
 349          * @param string $mode Lock wait mode - "wait" or "nowait"
 350          * @return array The new backoffs account for $backoffs and the latest file data
 351          */
 352         private function syncBackoffDeltas( array $backoffs, array &$deltas, $mode = 'wait' ) {
 353                 if ( !$deltas ) {
 354                         return $this->loadBackoffs( $backoffs, $mode );
 355                 }
 356
 357                 $noblock = ( $mode === 'nowait' ) ? LOCK_NB : 0;
 358                 $file = wfTempDir() . '/mw-runJobs-backoffs.json';
 359                 $handle = fopen( $file, 'wb+' );
 360                 if ( !flock( $handle, LOCK_EX | $noblock ) ) {
 361                         fclose( $handle );
 362                         return $backoffs; // don't wait on lock
 363                 }
 364                 $ctime = microtime( true );
 365                 $content = stream_get_contents( $handle );
 366                 $cBackoffs = json_decode( $content, true ) ?: array();
 367                 foreach ( $deltas as $type => $seconds ) {
 368                         $cBackoffs[$type] = isset( $cBackoffs[$type] ) && $cBackoffs[$type] >= $ctime
 369                                 ? $cBackoffs[$type] + $seconds
 370                                 : $ctime + $seconds;
 371                 }
 372                 foreach ( $cBackoffs as $type => $timestamp ) {
 373                         if ( $timestamp < $ctime ) {
 374                                 unset( $cBackoffs[$type] );
 375                         }
 376                 }
 377                 ftruncate( $handle, 0 );
 378                 fwrite( $handle, json_encode( $cBackoffs ) );
 379                 flock( $handle, LOCK_UN );
 380                 fclose( $handle );
 381
 382                 $deltas = array();
 383
 384                 return $cBackoffs;
 385         }
 386
 387         /**
 388          * Make sure that this script is not too close to the memory usage limit.
 389          * It is better to die in between jobs than OOM right in the middle of one.
 390          * @throws MWException
 391          */
 392         private function assertMemoryOK() {
 393                 static $maxBytes = null;
 394                 if ( $maxBytes === null ) {
 395                         $m = array();
 396                         if ( preg_match( '!^(\d+)(k|m|g|)$!i', ini_get( 'memory_limit' ), $m ) ) {
 397                                 list( , $num, $unit ) = $m;
 398                                 $conv = array( 'g' => 1073741824, 'm' => 1048576, 'k' => 1024, '' => 1 );
 399                                 $maxBytes = $num * $conv[strtolower( $unit )];
 400                         } else {
 401                                 $maxBytes = 0;
 402                         }
 403                 }
 404                 $usedBytes = memory_get_usage();
 405                 if ( $maxBytes && $usedBytes >= 0.95 * $maxBytes ) {
 406                         throw new MWException( "Detected excessive memory usage ($usedBytes/$maxBytes)." );
 407                 }
 408         }
 409
 410         /**
 411          * Log the job message
 412          * @param string $msg The message to log
 413          */
 414         private function debugCallback( $msg ) {
 415                 if ( $this->debug ) {
 416                         call_user_func_array( $this->debug, array( wfTimestamp( TS_DB ) . " $msg\n" ) );
 417                 }
 418         }
 419
 420         /**
 421          * Issue a commit on all masters who are currently in a transaction and have
 422          * made changes to the database. It also supports sometimes waiting for the
 423          * local wiki's slaves to catch up. See the documentation for
 424          * $wgJobSerialCommitThreshold for more.
 425          *
 426          * @param Job $job
 427          * @throws DBError
 428          */
 429         private function commitMasterChanges( Job $job ) {
 430                 global $wgJobSerialCommitThreshold;
 431
 432                 $lb = wfGetLB( wfWikiID() );
 433                 if ( $wgJobSerialCommitThreshold !== false ) {
 434                         // Generally, there is one master connection to the local DB
 435                         $dbwSerial = $lb->getAnyOpenConnection( $lb->getWriterIndex() );
 436                 } else {
 437                         $dbwSerial = false;
 438                 }
 439
 440                 if ( !$dbwSerial
 441                         || !$dbwSerial->namedLocksEnqueue()
 442                         || $dbwSerial->pendingWriteQueryDuration() < $wgJobSerialCommitThreshold
 443                 ) {
 444                         // Writes are all to foreign DBs, named locks don't form queues,
 445                         // or $wgJobSerialCommitThreshold is not reached; commit changes now
 446                         wfGetLBFactory()->commitMasterChanges();
 447                         return;
 448                 }
 449
 450                 $ms = intval( 1000 * $dbwSerial->pendingWriteQueryDuration() );
 451                 $msg = $job->toString() . " COMMIT ENQUEUED [{$ms}ms of writes]";
 452                 $this->logger->info( $msg );
 453                 $this->debugCallback( $msg );
 454
 455                 // Wait for an exclusive lock to commit
 456                 if ( !$dbwSerial->lock( 'jobrunner-serial-commit', __METHOD__, 30 ) ) {
 457                         // This will trigger a rollback in the main loop
 458                         throw new DBError( $dbwSerial, "Timed out waiting on commit queue." );
 459                 }
 460                 // Wait for the generic slave to catch up
 461                 $pos = $lb->getMasterPos();
 462                 if ( $pos ) {
 463                         $lb->waitForOne( $pos );
 464                 }
 465
 466                 $fname = __METHOD__;
 467                 // Re-ping all masters with transactions. This throws DBError if some
 468                 // connection died while waiting on locks/slaves, triggering a rollback.
 469                 wfGetLBFactory()->forEachLB( function( LoadBalancer $lb ) use ( $fname ) {
 470                         $lb->forEachOpenConnection( function( DatabaseBase $conn ) use ( $fname ) {
 471                                 if ( $conn->writesOrCallbacksPending() ) {
 472                                         $conn->query( "SELECT 1", $fname );
 473                                 }
 474                         } );
 475                 } );
 476
 477                 // Actually commit the DB master changes
 478                 wfGetLBFactory()->commitMasterChanges();
 479
 480                 // Release the lock
 481                 $dbwSerial->unlock( 'jobrunner-serial-commit', __METHOD__ );
 482         }
 483 }