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                 // Catch huge single updates that lead to slave lag
 113                 $trxProfiler = Profiler::instance()->getTransactionProfiler();
 114                 $trxProfiler->setLogger( LoggerFactory::getInstance( 'DBPerformance' ) );
 115                 $trxProfiler->setExpectations( $wgTrxProfilerLimits['JobRunner'], __METHOD__ );
 116
 117                 // Bail out if there is too much DB lag.
 118                 // This check should not block as we want to try other wiki queues.
 119                 $maxAllowedLag = 3;
 120                 list( , $maxLag ) = wfGetLB( wfWikiID() )->getMaxLag();
 121                 if ( $maxLag >= $maxAllowedLag ) {
 122                         $response['reached'] = 'slave-lag-limit';
 123                         return $response;
 124                 }
 125
 126                 $group = JobQueueGroup::singleton();
 127
 128                 // Flush any pending DB writes for sanity
 129                 wfGetLBFactory()->commitAll();
 130
 131                 // Some jobs types should not run until a certain timestamp
 132                 $backoffs = array(); // map of (type => UNIX expiry)
 133                 $backoffDeltas = array(); // map of (type => seconds)
 134                 $wait = 'wait'; // block to read backoffs the first time
 135
 136                 $stats = RequestContext::getMain()->getStats();
 137                 $jobsPopped = 0;
 138                 $timeMsTotal = 0;
 139                 $flags = JobQueueGroup::USE_CACHE;
 140                 $startTime = microtime( true ); // time since jobs started running
 141                 $checkLagPeriod = 1.0; // check slave lag this many seconds
 142                 $lastCheckTime = 1; // timestamp of last slave check
 143                 do {
 144                         // Sync the persistent backoffs with concurrent runners
 145                         $backoffs = $this->syncBackoffDeltas( $backoffs, $backoffDeltas, $wait );
 146                         $blacklist = $noThrottle ? array() : array_keys( $backoffs );
 147                         $wait = 'nowait'; // less important now
 148
 149                         if ( $type === false ) {
 150                                 $job = $group->pop( JobQueueGroup::TYPE_DEFAULT, $flags, $blacklist );
 151                         } elseif ( in_array( $type, $blacklist ) ) {
 152                                 $job = false; // requested queue in backoff state
 153                         } else {
 154                                 $job = $group->pop( $type ); // job from a single queue
 155                         }
 156
 157                         if ( $job ) { // found a job
 158                                 $popTime = time();
 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                                 $jobStartTime = microtime( true );
 178                                 try {
 179                                         ++$jobsPopped;
 180                                         $status = $job->run();
 181                                         $error = $job->getLastError();
 182                                         $this->commitMasterChanges( $job );
 183
 184                                         DeferredUpdates::doUpdates();
 185                                         $this->commitMasterChanges( $job );
 186                                 } catch ( Exception $e ) {
 187                                         MWExceptionHandler::rollbackMasterChangesAndLog( $e );
 188                                         $status = false;
 189                                         $error = get_class( $e ) . ': ' . $e->getMessage();
 190                                         MWExceptionHandler::logException( $e );
 191                                 }
 192                                 // Commit all outstanding connections that are in a transaction
 193                                 // to get a fresh repeatable read snapshot on every connection.
 194                                 wfGetLBFactory()->commitAll();
 195                                 $timeMs = intval( ( microtime( true ) - $jobStartTime ) * 1000 );
 196                                 $timeMsTotal += $timeMs;
 197
 198                                 // Record how long jobs wait before getting popped
 199                                 $readyTs = $job->getReadyTimestamp();
 200                                 if ( $readyTs ) {
 201                                         $pickupDelay = $popTime - $readyTs;
 202                                         $stats->timing( 'jobqueue.pickup_delay.all', 1000 * $pickupDelay );
 203                                         $stats->timing( "jobqueue.pickup_delay.$jType", 1000 * $pickupDelay );
 204                                 }
 205                                 // Record root job age for jobs being run
 206                                 $root = $job->getRootJobParams();
 207                                 if ( $root['rootJobTimestamp'] ) {
 208                                         $age = $popTime - wfTimestamp( TS_UNIX, $root['rootJobTimestamp'] );
 209                                         $stats->timing( "jobqueue.pickup_root_age.$jType", 1000 * $age );
 210                                 }
 211                                 // Track the execution time for jobs
 212                                 $stats->timing( "jobqueue.run.$jType", $timeMs );
 213
 214                                 // Mark the job as done on success or when the job cannot be retried
 215                                 if ( $status !== false || !$job->allowRetries() ) {
 216                                         $group->ack( $job ); // done
 217                                 }
 218
 219                                 // Back off of certain jobs for a while (for throttling and for errors)
 220                                 if ( $status === false && mt_rand( 0, 49 ) == 0 ) {
 221                                         $ttw = max( $ttw, 30 ); // too many errors
 222                                         $backoffDeltas[$jType] = isset( $backoffDeltas[$jType] )
 223                                                 ? $backoffDeltas[$jType] + $ttw
 224                                                 : $ttw;
 225                                 }
 226
 227                                 if ( $status === false ) {
 228                                         $msg = $job->toString() . " t=$timeMs error={$error}";
 229                                         $this->logger->error( $msg );
 230                                         $this->debugCallback( $msg );
 231                                 } else {
 232                                         $msg = $job->toString() . " t=$timeMs good";
 233                                         $this->logger->info( $msg );
 234                                         $this->debugCallback( $msg );
 235                                 }
 236
 237                                 $response['jobs'][] = array(
 238                                         'type'   => $jType,
 239                                         'status' => ( $status === false ) ? 'failed' : 'ok',
 240                                         'error'  => $error,
 241                                         'time'   => $timeMs
 242                                 );
 243
 244                                 // Break out if we hit the job count or wall time limits...
 245                                 if ( $maxJobs && $jobsPopped >= $maxJobs ) {
 246                                         $response['reached'] = 'job-limit';
 247                                         break;
 248                                 } elseif ( $maxTime && ( microtime( true ) - $startTime ) > $maxTime ) {
 249                                         $response['reached'] = 'time-limit';
 250                                         break;
 251                                 }
 252
 253                                 // Don't let any of the main DB slaves get backed up.
 254                                 // This only waits for so long before exiting and letting
 255                                 // other wikis in the farm (on different masters) get a chance.
 256                                 $timePassed = microtime( true ) - $lastCheckTime;
 257                                 if ( $timePassed >= $checkLagPeriod || $timePassed < 0 ) {
 258                                         if ( !wfWaitForSlaves( $lastCheckTime, false, '*', $maxAllowedLag ) ) {
 259                                                 $response['reached'] = 'slave-lag-limit';
 260                                                 break;
 261                                         }
 262                                         $lastCheckTime = microtime( true );
 263                                 }
 264                                 // Don't let any queue slaves/backups fall behind
 265                                 if ( $jobsPopped > 0 && ( $jobsPopped % 100 ) == 0 ) {
 266                                         $group->waitForBackups();
 267                                 }
 268
 269                                 // Bail if near-OOM instead of in a job
 270                                 if ( !$this->checkMemoryOK() ) {
 271                                         $response['reached'] = 'memory-limit';
 272                                         break;
 273                                 }
 274                         }
 275                 } while ( $job ); // stop when there are no jobs
 276
 277                 // Sync the persistent backoffs for the next runJobs.php pass
 278                 if ( $backoffDeltas ) {
 279                         $this->syncBackoffDeltas( $backoffs, $backoffDeltas, 'wait' );
 280                 }
 281
 282                 $response['backoffs'] = $backoffs;
 283                 $response['elapsed'] = $timeMsTotal;
 284
 285                 return $response;
 286         }
 287
 288         /**
 289          * @param Job $job
 290          * @return int Seconds for this runner to avoid doing more jobs of this type
 291          * @see $wgJobBackoffThrottling
 292          */
 293         private function getBackoffTimeToWait( Job $job ) {
 294                 global $wgJobBackoffThrottling;
 295
 296                 if ( !isset( $wgJobBackoffThrottling[$job->getType()] ) ||
 297                         $job instanceof DuplicateJob // no work was done
 298                 ) {
 299                         return 0; // not throttled
 300                 }
 301
 302                 $itemsPerSecond = $wgJobBackoffThrottling[$job->getType()];
 303                 if ( $itemsPerSecond <= 0 ) {
 304                         return 0; // not throttled
 305                 }
 306
 307                 $seconds = 0;
 308                 if ( $job->workItemCount() > 0 ) {
 309                         $exactSeconds = $job->workItemCount() / $itemsPerSecond;
 310                         // use randomized rounding
 311                         $seconds = floor( $exactSeconds );
 312                         $remainder = $exactSeconds - $seconds;
 313                         $seconds += ( mt_rand() / mt_getrandmax() < $remainder ) ? 1 : 0;
 314                 }
 315
 316                 return (int)$seconds;
 317         }
 318
 319         /**
 320          * Get the previous backoff expiries from persistent storage
 321          * On I/O or lock acquisition failure this returns the original $backoffs.
 322          *
 323          * @param array $backoffs Map of (job type => UNIX timestamp)
 324          * @param string $mode Lock wait mode - "wait" or "nowait"
 325          * @return array Map of (job type => backoff expiry timestamp)
 326          */
 327         private function loadBackoffs( array $backoffs, $mode = 'wait' ) {
 328                 $file = wfTempDir() . '/mw-runJobs-backoffs.json';
 329                 if ( is_file( $file ) ) {
 330                         $noblock = ( $mode === 'nowait' ) ? LOCK_NB : 0;
 331                         $handle = fopen( $file, 'rb' );
 332                         if ( !flock( $handle, LOCK_SH | $noblock ) ) {
 333                                 fclose( $handle );
 334                                 return $backoffs; // don't wait on lock
 335                         }
 336                         $content = stream_get_contents( $handle );
 337                         flock( $handle, LOCK_UN );
 338                         fclose( $handle );
 339                         $ctime = microtime( true );
 340                         $cBackoffs = json_decode( $content, true ) ?: array();
 341                         foreach ( $cBackoffs as $type => $timestamp ) {
 342                                 if ( $timestamp < $ctime ) {
 343                                         unset( $cBackoffs[$type] );
 344                                 }
 345                         }
 346                 } else {
 347                         $cBackoffs = array();
 348                 }
 349
 350                 return $cBackoffs;
 351         }
 352
 353         /**
 354          * Merge the current backoff expiries from persistent storage
 355          *
 356          * The $deltas map is set to an empty array on success.
 357          * On I/O or lock acquisition failure this returns the original $backoffs.
 358          *
 359          * @param array $backoffs Map of (job type => UNIX timestamp)
 360          * @param array $deltas Map of (job type => seconds)
 361          * @param string $mode Lock wait mode - "wait" or "nowait"
 362          * @return array The new backoffs account for $backoffs and the latest file data
 363          */
 364         private function syncBackoffDeltas( array $backoffs, array &$deltas, $mode = 'wait' ) {
 365                 if ( !$deltas ) {
 366                         return $this->loadBackoffs( $backoffs, $mode );
 367                 }
 368
 369                 $noblock = ( $mode === 'nowait' ) ? LOCK_NB : 0;
 370                 $file = wfTempDir() . '/mw-runJobs-backoffs.json';
 371                 $handle = fopen( $file, 'wb+' );
 372                 if ( !flock( $handle, LOCK_EX | $noblock ) ) {
 373                         fclose( $handle );
 374                         return $backoffs; // don't wait on lock
 375                 }
 376                 $ctime = microtime( true );
 377                 $content = stream_get_contents( $handle );
 378                 $cBackoffs = json_decode( $content, true ) ?: array();
 379                 foreach ( $deltas as $type => $seconds ) {
 380                         $cBackoffs[$type] = isset( $cBackoffs[$type] ) && $cBackoffs[$type] >= $ctime
 381                                 ? $cBackoffs[$type] + $seconds
 382                                 : $ctime + $seconds;
 383                 }
 384                 foreach ( $cBackoffs as $type => $timestamp ) {
 385                         if ( $timestamp < $ctime ) {
 386                                 unset( $cBackoffs[$type] );
 387                         }
 388                 }
 389                 ftruncate( $handle, 0 );
 390                 fwrite( $handle, json_encode( $cBackoffs ) );
 391                 flock( $handle, LOCK_UN );
 392                 fclose( $handle );
 393
 394                 $deltas = array();
 395
 396                 return $cBackoffs;
 397         }
 398
 399         /**
 400          * Make sure that this script is not too close to the memory usage limit.
 401          * It is better to die in between jobs than OOM right in the middle of one.
 402          * @return bool
 403          */
 404         private function checkMemoryOK() {
 405                 static $maxBytes = null;
 406                 if ( $maxBytes === null ) {
 407                         $m = array();
 408                         if ( preg_match( '!^(\d+)(k|m|g|)$!i', ini_get( 'memory_limit' ), $m ) ) {
 409                                 list( , $num, $unit ) = $m;
 410                                 $conv = array( 'g' => 1073741824, 'm' => 1048576, 'k' => 1024, '' => 1 );
 411                                 $maxBytes = $num * $conv[strtolower( $unit )];
 412                         } else {
 413                                 $maxBytes = 0;
 414                         }
 415                 }
 416                 $usedBytes = memory_get_usage();
 417                 if ( $maxBytes && $usedBytes >= 0.95 * $maxBytes ) {
 418                         $msg = "Detected excessive memory usage ($usedBytes/$maxBytes).";
 419                         $this->debugCallback( $msg );
 420                         $this->logger->error( $msg );
 421
 422                         return false;
 423                 }
 424
 425                 return true;
 426         }
 427
 428         /**
 429          * Log the job message
 430          * @param string $msg The message to log
 431          */
 432         private function debugCallback( $msg ) {
 433                 if ( $this->debug ) {
 434                         call_user_func_array( $this->debug, array( wfTimestamp( TS_DB ) . " $msg\n" ) );
 435                 }
 436         }
 437
 438         /**
 439          * Issue a commit on all masters who are currently in a transaction and have
 440          * made changes to the database. It also supports sometimes waiting for the
 441          * local wiki's slaves to catch up. See the documentation for
 442          * $wgJobSerialCommitThreshold for more.
 443          *
 444          * @param Job $job
 445          * @throws DBError
 446          */
 447         private function commitMasterChanges( Job $job ) {
 448                 global $wgJobSerialCommitThreshold;
 449
 450                 $lb = wfGetLB( wfWikiID() );
 451                 if ( $wgJobSerialCommitThreshold !== false ) {
 452                         // Generally, there is one master connection to the local DB
 453                         $dbwSerial = $lb->getAnyOpenConnection( $lb->getWriterIndex() );
 454                 } else {
 455                         $dbwSerial = false;
 456                 }
 457
 458                 if ( !$dbwSerial
 459                         || !$dbwSerial->namedLocksEnqueue()
 460                         || $dbwSerial->pendingWriteQueryDuration() < $wgJobSerialCommitThreshold
 461                 ) {
 462                         // Writes are all to foreign DBs, named locks don't form queues,
 463                         // or $wgJobSerialCommitThreshold is not reached; commit changes now
 464                         wfGetLBFactory()->commitMasterChanges();
 465                         return;
 466                 }
 467
 468                 $ms = intval( 1000 * $dbwSerial->pendingWriteQueryDuration() );
 469                 $msg = $job->toString() . " COMMIT ENQUEUED [{$ms}ms of writes]";
 470                 $this->logger->info( $msg );
 471                 $this->debugCallback( $msg );
 472
 473                 // Wait for an exclusive lock to commit
 474                 if ( !$dbwSerial->lock( 'jobrunner-serial-commit', __METHOD__, 30 ) ) {
 475                         // This will trigger a rollback in the main loop
 476                         throw new DBError( $dbwSerial, "Timed out waiting on commit queue." );
 477                 }
 478                 // Wait for the generic slave to catch up
 479                 $pos = $lb->getMasterPos();
 480                 if ( $pos ) {
 481                         $lb->waitForOne( $pos );
 482                 }
 483
 484                 $fname = __METHOD__;
 485                 // Re-ping all masters with transactions. This throws DBError if some
 486                 // connection died while waiting on locks/slaves, triggering a rollback.
 487                 wfGetLBFactory()->forEachLB( function( LoadBalancer $lb ) use ( $fname ) {
 488                         $lb->forEachOpenConnection( function( IDatabase $conn ) use ( $fname ) {
 489                                 if ( $conn->writesOrCallbacksPending() ) {
 490                                         $conn->query( "SELECT 1", $fname );
 491                                 }
 492                         } );
 493                 } );
 494
 495                 // Actually commit the DB master changes
 496                 wfGetLBFactory()->commitMasterChanges();
 497
 498                 // Release the lock
 499                 $dbwSerial->unlock( 'jobrunner-serial-commit', __METHOD__ );
 500         }
 501 }