3 * Job queue runner utility methods
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7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
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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.
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17 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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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
;
31 * Job queue runner utility methods
36 class JobRunner
implements LoggerAwareInterface
{
37 /** @var callable|null Debug output handler */
41 * @var LoggerInterface $logger
45 const MAX_ALLOWED_LAG
= 3; // abort if more than this much DB lag is present
46 const LAG_CHECK_PERIOD
= 1.0; // check replica DB lag this many seconds
47 const ERROR_BACKOFF_TTL
= 1; // seconds to back off a queue due to errors
50 * @param callable $debug Optional debug output handler
52 public function setDebugHandler( $debug ) {
53 $this->debug
= $debug;
57 * @param LoggerInterface $logger
60 public function setLogger( LoggerInterface
$logger ) {
61 $this->logger
= $logger;
65 * @param LoggerInterface $logger
67 public function __construct( LoggerInterface
$logger = null ) {
68 if ( $logger === null ) {
69 $logger = LoggerFactory
::getInstance( 'runJobs' );
71 $this->setLogger( $logger );
75 * Run jobs of the specified number/type for the specified time
77 * The response map has a 'job' field that lists status of each job, including:
78 * - type : the job type
79 * - status : ok/failed
80 * - error : any error message string
81 * - time : the job run time in ms
82 * The response map also has:
83 * - backoffs : the (job type => seconds) map of backoff times
84 * - elapsed : the total time spent running tasks in ms
85 * - reached : the reason the script finished, one of (none-ready, job-limit, time-limit,
88 * This method outputs status information only if a debug handler was set.
89 * Any exceptions are caught and logged, but are not reported as output.
91 * @param array $options Map of parameters:
92 * - type : the job type (or false for the default types)
93 * - maxJobs : maximum number of jobs to run
94 * - maxTime : maximum time in seconds before stopping
95 * - throttle : whether to respect job backoff configuration
96 * @return array Summary response that can easily be JSON serialized
98 public function run( array $options ) {
99 global $wgJobClasses, $wgTrxProfilerLimits;
101 $response = [ 'jobs' => [], 'reached' => 'none-ready' ];
103 $type = isset( $options['type'] ) ?
$options['type'] : false;
104 $maxJobs = isset( $options['maxJobs'] ) ?
$options['maxJobs'] : false;
105 $maxTime = isset( $options['maxTime'] ) ?
$options['maxTime'] : false;
106 $noThrottle = isset( $options['throttle'] ) && !$options['throttle'];
108 // Bail if job type is invalid
109 if ( $type !== false && !isset( $wgJobClasses[$type] ) ) {
110 $response['reached'] = 'none-possible';
113 // Bail out if DB is in read-only mode
114 if ( wfReadOnly() ) {
115 $response['reached'] = 'read-only';
119 $lbFactory = MediaWikiServices
::getInstance()->getDBLoadBalancerFactory();
120 // Bail out if there is too much DB lag.
121 // This check should not block as we want to try other wiki queues.
122 list( , $maxLag ) = $lbFactory->getMainLB( wfWikiID() )->getMaxLag();
123 if ( $maxLag >= self
::MAX_ALLOWED_LAG
) {
124 $response['reached'] = 'replica-lag-limit';
128 // Flush any pending DB writes for sanity
129 $lbFactory->commitAll( __METHOD__
);
131 // Catch huge single updates that lead to replica DB lag
132 $trxProfiler = Profiler
::instance()->getTransactionProfiler();
133 $trxProfiler->setLogger( LoggerFactory
::getInstance( 'DBPerformance' ) );
134 $trxProfiler->setExpectations( $wgTrxProfilerLimits['JobRunner'], __METHOD__
);
136 // Some jobs types should not run until a certain timestamp
137 $backoffs = []; // map of (type => UNIX expiry)
138 $backoffDeltas = []; // map of (type => seconds)
139 $wait = 'wait'; // block to read backoffs the first time
141 $group = JobQueueGroup
::singleton();
142 $stats = MediaWikiServices
::getInstance()->getStatsdDataFactory();
145 $startTime = microtime( true ); // time since jobs started running
146 $lastCheckTime = 1; // timestamp of last replica DB check
148 // Sync the persistent backoffs with concurrent runners
149 $backoffs = $this->syncBackoffDeltas( $backoffs, $backoffDeltas, $wait );
150 $blacklist = $noThrottle ?
[] : array_keys( $backoffs );
151 $wait = 'nowait'; // less important now
153 if ( $type === false ) {
155 JobQueueGroup
::TYPE_DEFAULT
,
156 JobQueueGroup
::USE_CACHE
,
159 } elseif ( in_array( $type, $blacklist ) ) {
160 $job = false; // requested queue in backoff state
162 $job = $group->pop( $type ); // job from a single queue
164 $lbFactory->commitMasterChanges( __METHOD__
); // flush any JobQueueDB writes
166 if ( $job ) { // found a job
169 $jType = $job->getType();
171 WebRequest
::overrideRequestId( $job->getRequestId() );
173 // Back off of certain jobs for a while (for throttling and for errors)
174 $ttw = $this->getBackoffTimeToWait( $job );
176 // Always add the delta for other runners in case the time running the
177 // job negated the backoff for each individually but not collectively.
178 $backoffDeltas[$jType] = isset( $backoffDeltas[$jType] )
179 ?
$backoffDeltas[$jType] +
$ttw
181 $backoffs = $this->syncBackoffDeltas( $backoffs, $backoffDeltas, $wait );
184 $info = $this->executeJob( $job, $lbFactory, $stats, $popTime );
185 if ( $info['status'] !== false ||
!$job->allowRetries() ) {
186 $group->ack( $job ); // succeeded or job cannot be retried
187 $lbFactory->commitMasterChanges( __METHOD__
); // flush any JobQueueDB writes
190 // Back off of certain jobs for a while (for throttling and for errors)
191 if ( $info['status'] === false && mt_rand( 0, 49 ) == 0 ) {
192 $ttw = max( $ttw, self
::ERROR_BACKOFF_TTL
); // too many errors
193 $backoffDeltas[$jType] = isset( $backoffDeltas[$jType] )
194 ?
$backoffDeltas[$jType] +
$ttw
198 $response['jobs'][] = [
200 'status' => ( $info['status'] === false ) ?
'failed' : 'ok',
201 'error' => $info['error'],
202 'time' => $info['timeMs']
204 $timeMsTotal +
= $info['timeMs'];
206 // Break out if we hit the job count or wall time limits...
207 if ( $maxJobs && $jobsPopped >= $maxJobs ) {
208 $response['reached'] = 'job-limit';
210 } elseif ( $maxTime && ( microtime( true ) - $startTime ) > $maxTime ) {
211 $response['reached'] = 'time-limit';
215 // Don't let any of the main DB replica DBs get backed up.
216 // This only waits for so long before exiting and letting
217 // other wikis in the farm (on different masters) get a chance.
218 $timePassed = microtime( true ) - $lastCheckTime;
219 if ( $timePassed >= self
::LAG_CHECK_PERIOD ||
$timePassed < 0 ) {
221 $lbFactory->waitForReplication( [
222 'ifWritesSince' => $lastCheckTime,
223 'timeout' => self
::MAX_ALLOWED_LAG
225 } catch ( DBReplicationWaitError
$e ) {
226 $response['reached'] = 'replica-lag-limit';
229 $lastCheckTime = microtime( true );
231 // Don't let any queue replica DBs/backups fall behind
232 if ( $jobsPopped > 0 && ( $jobsPopped %
100 ) == 0 ) {
233 $group->waitForBackups();
236 // Bail if near-OOM instead of in a job
237 if ( !$this->checkMemoryOK() ) {
238 $response['reached'] = 'memory-limit';
242 } while ( $job ); // stop when there are no jobs
244 // Sync the persistent backoffs for the next runJobs.php pass
245 if ( $backoffDeltas ) {
246 $this->syncBackoffDeltas( $backoffs, $backoffDeltas, 'wait' );
249 $response['backoffs'] = $backoffs;
250 $response['elapsed'] = $timeMsTotal;
257 * @param LBFactory $lbFactory
258 * @param StatsdDataFactory $stats
259 * @param float $popTime
260 * @return array Map of status/error/timeMs
262 private function executeJob( Job
$job, LBFactory
$lbFactory, $stats, $popTime ) {
263 $jType = $job->getType();
264 $msg = $job->toString() . " STARTING";
265 $this->logger
->debug( $msg );
266 $this->debugCallback( $msg );
269 $rssStart = $this->getMaxRssKb();
270 $jobStartTime = microtime( true );
272 $fnameTrxOwner = get_class( $job ) . '::run'; // give run() outer scope
273 $lbFactory->beginMasterChanges( $fnameTrxOwner );
274 $status = $job->run();
275 $error = $job->getLastError();
276 $this->commitMasterChanges( $lbFactory, $job, $fnameTrxOwner );
277 // Run any deferred update tasks; doUpdates() manages transactions itself
278 DeferredUpdates
::doUpdates();
279 } catch ( Exception
$e ) {
280 MWExceptionHandler
::rollbackMasterChangesAndLog( $e );
282 $error = get_class( $e ) . ': ' . $e->getMessage();
283 MWExceptionHandler
::logException( $e );
285 // Always attempt to call teardown() even if Job throws exception.
288 } catch ( Exception
$e ) {
289 MWExceptionHandler
::logException( $e );
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();
301 // Record how long jobs wait before getting popped
302 $readyTs = $job->getReadyTimestamp();
304 $pickupDelay = max( 0, $popTime - $readyTs );
305 $stats->timing( 'jobqueue.pickup_delay.all', 1000 * $pickupDelay );
306 $stats->timing( "jobqueue.pickup_delay.$jType", 1000 * $pickupDelay );
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 );
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 );
321 if ( $status === false ) {
322 $msg = $job->toString() . " t=$timeMs error={$error}";
323 $this->logger
->error( $msg );
324 $this->debugCallback( $msg );
326 $msg = $job->toString() . " t=$timeMs good";
327 $this->logger
->info( $msg );
328 $this->debugCallback( $msg );
331 return [ 'status' => $status, 'error' => $error, 'timeMs' => $timeMs ];
335 * @return int|null Max memory RSS in kilobytes
337 private function getMaxRssKb() {
338 $info = wfGetRusage() ?
: [];
339 // see http://linux.die.net/man/2/getrusage
340 return isset( $info['ru_maxrss'] ) ?
(int)$info['ru_maxrss'] : null;
345 * @return int Seconds for this runner to avoid doing more jobs of this type
346 * @see $wgJobBackoffThrottling
348 private function getBackoffTimeToWait( Job
$job ) {
349 global $wgJobBackoffThrottling;
351 if ( !isset( $wgJobBackoffThrottling[$job->getType()] ) ||
352 $job instanceof DuplicateJob
// no work was done
354 return 0; // not throttled
357 $itemsPerSecond = $wgJobBackoffThrottling[$job->getType()];
358 if ( $itemsPerSecond <= 0 ) {
359 return 0; // not throttled
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() < $remainder ) ?
1 : 0;
371 return (int)$seconds;
375 * Get the previous backoff expiries from persistent storage
376 * On I/O or lock acquisition failure this returns the original $backoffs.
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)
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 ) ) {
389 return $backoffs; // don't wait on lock
391 $content = stream_get_contents( $handle );
392 flock( $handle, LOCK_UN
);
394 $ctime = microtime( true );
395 $cBackoffs = json_decode( $content, true ) ?
: [];
396 foreach ( $cBackoffs as $type => $timestamp ) {
397 if ( $timestamp < $ctime ) {
398 unset( $cBackoffs[$type] );
409 * Merge the current backoff expiries from persistent storage
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.
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
419 private function syncBackoffDeltas( array $backoffs, array &$deltas, $mode = 'wait' ) {
421 return $this->loadBackoffs( $backoffs, $mode );
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 ) ) {
429 return $backoffs; // don't wait on lock
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
439 foreach ( $cBackoffs as $type => $timestamp ) {
440 if ( $timestamp < $ctime ) {
441 unset( $cBackoffs[$type] );
444 ftruncate( $handle, 0 );
445 fwrite( $handle, json_encode( $cBackoffs ) );
446 flock( $handle, LOCK_UN
);
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.
459 private function checkMemoryOK() {
460 static $maxBytes = null;
461 if ( $maxBytes === null ) {
463 if ( preg_match( '!^(\d+)(k|m|g|)$!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 )];
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 );
484 * Log the job message
485 * @param string $msg The message to log
487 private function debugCallback( $msg ) {
488 if ( $this->debug
) {
489 call_user_func_array( $this->debug
, [ wfTimestamp( TS_DB
) . " $msg\n" ] );
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.
499 * @param LBFactory $lbFactory
501 * @param string $fnameTrxOwner
504 private function commitMasterChanges( LBFactory
$lbFactory, Job
$job, $fnameTrxOwner ) {
505 global $wgJobSerialCommitThreshold;
507 $lb = $lbFactory->getMainLB( wfWikiID() );
508 if ( $wgJobSerialCommitThreshold !== false && $lb->getServerCount() > 1 ) {
509 // Generally, there is one master connection to the local DB
510 $dbwSerial = $lb->getAnyOpenConnection( $lb->getWriterIndex() );
511 // We need natively blocking fast locks
512 if ( $dbwSerial && $dbwSerial->namedLocksEnqueue() ) {
513 $time = $dbwSerial->pendingWriteQueryDuration( $dbwSerial::ESTIMATE_DB_APPLY
);
514 if ( $time < $wgJobSerialCommitThreshold ) {
521 // There are no replica DBs or writes are all to foreign DB (we don't handle that)
526 $lbFactory->commitMasterChanges( $fnameTrxOwner );
530 $ms = intval( 1000 * $dbwSerial->pendingWriteQueryDuration() );
531 $msg = $job->toString() . " COMMIT ENQUEUED [{$ms}ms of writes]";
532 $this->logger
->info( $msg );
533 $this->debugCallback( $msg );
535 // Wait for an exclusive lock to commit
536 if ( !$dbwSerial->lock( 'jobrunner-serial-commit', __METHOD__
, 30 ) ) {
537 // This will trigger a rollback in the main loop
538 throw new DBError( $dbwSerial, "Timed out waiting on commit queue." );
540 $unlocker = new ScopedCallback( function () use ( $dbwSerial ) {
541 $dbwSerial->unlock( 'jobrunner-serial-commit', __METHOD__
);
544 // Wait for the replica DBs to catch up
545 $pos = $lb->getMasterPos();
547 $lb->waitForAll( $pos );
550 // Actually commit the DB master changes
551 $lbFactory->commitMasterChanges( $fnameTrxOwner );
552 ScopedCallback
::consume( $unlocker );