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