Current File : /www/varak.net/wiki.varak.net/includes/jobqueue/JobRunner.php
<?php
/**
* Job queue runner utility methods
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
* @ingroup JobQueue
*/
use MediaWiki\MediaWikiServices;
use MediaWiki\Logger\LoggerFactory;
use Liuggio\StatsdClient\Factory\StatsdDataFactory;
use Psr\Log\LoggerAwareInterface;
use Psr\Log\LoggerInterface;
use Wikimedia\ScopedCallback;
use Wikimedia\Rdbms\LBFactory;
use Wikimedia\Rdbms\DBError;
/**
* Job queue runner utility methods
*
* @ingroup JobQueue
* @since 1.24
*/
class JobRunner implements LoggerAwareInterface {
/** @var Config */
protected $config;
/** @var callable|null Debug output handler */
protected $debug;
/**
* @var LoggerInterface $logger
*/
protected $logger;
const MAX_ALLOWED_LAG = 3; // abort if more than this much DB lag is present
const LAG_CHECK_PERIOD = 1.0; // check replica DB lag this many seconds
const ERROR_BACKOFF_TTL = 1; // seconds to back off a queue due to errors
const READONLY_BACKOFF_TTL = 30; // seconds to back off a queue due to read-only errors
/**
* @param callable $debug Optional debug output handler
*/
public function setDebugHandler( $debug ) {
$this->debug = $debug;
}
/**
* @param LoggerInterface $logger
* @return void
*/
public function setLogger( LoggerInterface $logger ) {
$this->logger = $logger;
}
/**
* @param LoggerInterface|null $logger
*/
public function __construct( LoggerInterface $logger = null ) {
if ( $logger === null ) {
$logger = LoggerFactory::getInstance( 'runJobs' );
}
$this->setLogger( $logger );
$this->config = MediaWikiServices::getInstance()->getMainConfig();
}
/**
* Run jobs of the specified number/type for the specified time
*
* The response map has a 'job' field that lists status of each job, including:
* - type : the job type
* - status : ok/failed
* - error : any error message string
* - time : the job run time in ms
* The response map also has:
* - backoffs : the (job type => seconds) map of backoff times
* - elapsed : the total time spent running tasks in ms
* - reached : the reason the script finished, one of (none-ready, job-limit, time-limit,
* memory-limit)
*
* This method outputs status information only if a debug handler was set.
* Any exceptions are caught and logged, but are not reported as output.
*
* @param array $options Map of parameters:
* - type : the job type (or false for the default types)
* - maxJobs : maximum number of jobs to run
* - maxTime : maximum time in seconds before stopping
* - throttle : whether to respect job backoff configuration
* @return array Summary response that can easily be JSON serialized
*/
public function run( array $options ) {
$jobClasses = $this->config->get( 'JobClasses' );
$profilerLimits = $this->config->get( 'TrxProfilerLimits' );
$response = [ 'jobs' => [], 'reached' => 'none-ready' ];
$type = $options['type'] ?? false;
$maxJobs = $options['maxJobs'] ?? false;
$maxTime = $options['maxTime'] ?? false;
$noThrottle = isset( $options['throttle'] ) && !$options['throttle'];
// Bail if job type is invalid
if ( $type !== false && !isset( $jobClasses[$type] ) ) {
$response['reached'] = 'none-possible';
return $response;
}
// Bail out if DB is in read-only mode
if ( wfReadOnly() ) {
$response['reached'] = 'read-only';
return $response;
}
$lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
if ( $lbFactory->hasTransactionRound() ) {
throw new LogicException( __METHOD__ . ' called with an active transaction round.' );
}
// Bail out if there is too much DB lag.
// This check should not block as we want to try other wiki queues.
list( , $maxLag ) = $lbFactory->getMainLB()->getMaxLag();
if ( $maxLag >= self::MAX_ALLOWED_LAG ) {
$response['reached'] = 'replica-lag-limit';
return $response;
}
// Catch huge single updates that lead to replica DB lag
$trxProfiler = Profiler::instance()->getTransactionProfiler();
$trxProfiler->setLogger( LoggerFactory::getInstance( 'DBPerformance' ) );
$trxProfiler->setExpectations( $profilerLimits['JobRunner'], __METHOD__ );
// Some jobs types should not run until a certain timestamp
$backoffs = []; // map of (type => UNIX expiry)
$backoffDeltas = []; // map of (type => seconds)
$wait = 'wait'; // block to read backoffs the first time
$group = JobQueueGroup::singleton();
$stats = MediaWikiServices::getInstance()->getStatsdDataFactory();
$jobsPopped = 0;
$timeMsTotal = 0;
$startTime = microtime( true ); // time since jobs started running
$lastCheckTime = 1; // timestamp of last replica DB check
do {
// Sync the persistent backoffs with concurrent runners
$backoffs = $this->syncBackoffDeltas( $backoffs, $backoffDeltas, $wait );
$blacklist = $noThrottle ? [] : array_keys( $backoffs );
$wait = 'nowait'; // less important now
if ( $type === false ) {
$job = $group->pop(
JobQueueGroup::TYPE_DEFAULT,
JobQueueGroup::USE_CACHE,
$blacklist
);
} elseif ( in_array( $type, $blacklist ) ) {
$job = false; // requested queue in backoff state
} else {
$job = $group->pop( $type ); // job from a single queue
}
if ( $job ) { // found a job
++$jobsPopped;
$popTime = time();
$jType = $job->getType();
WebRequest::overrideRequestId( $job->getRequestId() );
// Back off of certain jobs for a while (for throttling and for errors)
$ttw = $this->getBackoffTimeToWait( $job );
if ( $ttw > 0 ) {
// Always add the delta for other runners in case the time running the
// job negated the backoff for each individually but not collectively.
$backoffDeltas[$jType] = isset( $backoffDeltas[$jType] )
? $backoffDeltas[$jType] + $ttw
: $ttw;
$backoffs = $this->syncBackoffDeltas( $backoffs, $backoffDeltas, $wait );
}
$info = $this->executeJob( $job, $lbFactory, $stats, $popTime );
if ( $info['status'] !== false || !$job->allowRetries() ) {
$group->ack( $job ); // succeeded or job cannot be retried
}
// Back off of certain jobs for a while (for throttling and for errors)
if ( $info['status'] === false && mt_rand( 0, 49 ) == 0 ) {
$ttw = max( $ttw, $this->getErrorBackoffTTL( $info['error'] ) );
$backoffDeltas[$jType] = isset( $backoffDeltas[$jType] )
? $backoffDeltas[$jType] + $ttw
: $ttw;
}
$response['jobs'][] = [
'type' => $jType,
'status' => ( $info['status'] === false ) ? 'failed' : 'ok',
'error' => $info['error'],
'time' => $info['timeMs']
];
$timeMsTotal += $info['timeMs'];
// Break out if we hit the job count or wall time limits...
if ( $maxJobs && $jobsPopped >= $maxJobs ) {
$response['reached'] = 'job-limit';
break;
} elseif ( $maxTime && ( microtime( true ) - $startTime ) > $maxTime ) {
$response['reached'] = 'time-limit';
break;
}
// Don't let any of the main DB replica DBs get backed up.
// This only waits for so long before exiting and letting
// other wikis in the farm (on different masters) get a chance.
$timePassed = microtime( true ) - $lastCheckTime;
if ( $timePassed >= self::LAG_CHECK_PERIOD || $timePassed < 0 ) {
$success = $lbFactory->waitForReplication( [
'ifWritesSince' => $lastCheckTime,
'timeout' => self::MAX_ALLOWED_LAG,
] );
if ( !$success ) {
$response['reached'] = 'replica-lag-limit';
break;
}
$lastCheckTime = microtime( true );
}
// Bail if near-OOM instead of in a job
if ( !$this->checkMemoryOK() ) {
$response['reached'] = 'memory-limit';
break;
}
}
} while ( $job ); // stop when there are no jobs
// Sync the persistent backoffs for the next runJobs.php pass
if ( $backoffDeltas ) {
$this->syncBackoffDeltas( $backoffs, $backoffDeltas, 'wait' );
}
$response['backoffs'] = $backoffs;
$response['elapsed'] = $timeMsTotal;
return $response;
}
/**
* @param string $error
* @return int TTL in seconds
*/
private function getErrorBackoffTTL( $error ) {
return strpos( $error, 'DBReadOnlyError' ) !== false
? self::READONLY_BACKOFF_TTL
: self::ERROR_BACKOFF_TTL;
}
/**
* @param Job $job
* @param LBFactory $lbFactory
* @param StatsdDataFactory $stats
* @param float $popTime
* @return array Map of status/error/timeMs
*/
private function executeJob( Job $job, LBFactory $lbFactory, $stats, $popTime ) {
$jType = $job->getType();
$msg = $job->toString() . " STARTING";
$this->logger->debug( $msg, [
'job_type' => $job->getType(),
] );
$this->debugCallback( $msg );
// Run the job...
$rssStart = $this->getMaxRssKb();
$jobStartTime = microtime( true );
try {
$fnameTrxOwner = get_class( $job ) . '::run'; // give run() outer scope
if ( !$job->hasExecutionFlag( $job::JOB_NO_EXPLICIT_TRX_ROUND ) ) {
$lbFactory->beginMasterChanges( $fnameTrxOwner );
}
$status = $job->run();
$error = $job->getLastError();
$this->commitMasterChanges( $lbFactory, $job, $fnameTrxOwner );
// Run any deferred update tasks; doUpdates() manages transactions itself
DeferredUpdates::doUpdates();
} catch ( Exception $e ) {
MWExceptionHandler::rollbackMasterChangesAndLog( $e );
$status = false;
$error = get_class( $e ) . ': ' . $e->getMessage();
}
// Always attempt to call teardown() even if Job throws exception.
try {
$job->teardown( $status );
} catch ( Exception $e ) {
MWExceptionHandler::logException( $e );
}
// Commit all outstanding connections that are in a transaction
// to get a fresh repeatable read snapshot on every connection.
// Note that jobs are still responsible for handling replica DB lag.
$lbFactory->flushReplicaSnapshots( __METHOD__ );
// Clear out title cache data from prior snapshots
MediaWikiServices::getInstance()->getLinkCache()->clear();
$timeMs = intval( ( microtime( true ) - $jobStartTime ) * 1000 );
$rssEnd = $this->getMaxRssKb();
// Record how long jobs wait before getting popped
$readyTs = $job->getReadyTimestamp();
if ( $readyTs ) {
$pickupDelay = max( 0, $popTime - $readyTs );
$stats->timing( 'jobqueue.pickup_delay.all', 1000 * $pickupDelay );
$stats->timing( "jobqueue.pickup_delay.$jType", 1000 * $pickupDelay );
}
// Record root job age for jobs being run
$rootTimestamp = $job->getRootJobParams()['rootJobTimestamp'];
if ( $rootTimestamp ) {
$age = max( 0, $popTime - wfTimestamp( TS_UNIX, $rootTimestamp ) );
$stats->timing( "jobqueue.pickup_root_age.$jType", 1000 * $age );
}
// Track the execution time for jobs
$stats->timing( "jobqueue.run.$jType", $timeMs );
// Track RSS increases for jobs (in case of memory leaks)
if ( $rssStart && $rssEnd ) {
$stats->updateCount( "jobqueue.rss_delta.$jType", $rssEnd - $rssStart );
}
if ( $status === false ) {
$msg = $job->toString() . " t={job_duration} error={job_error}";
$this->logger->error( $msg, [
'job_type' => $job->getType(),
'job_duration' => $timeMs,
'job_error' => $error,
] );
$msg = $job->toString() . " t=$timeMs error={$error}";
$this->debugCallback( $msg );
} else {
$msg = $job->toString() . " t={job_duration} good";
$this->logger->info( $msg, [
'job_type' => $job->getType(),
'job_duration' => $timeMs,
] );
$msg = $job->toString() . " t=$timeMs good";
$this->debugCallback( $msg );
}
return [ 'status' => $status, 'error' => $error, 'timeMs' => $timeMs ];
}
/**
* @return int|null Max memory RSS in kilobytes
*/
private function getMaxRssKb() {
$info = wfGetRusage() ?: [];
// see https://linux.die.net/man/2/getrusage
return isset( $info['ru_maxrss'] ) ? (int)$info['ru_maxrss'] : null;
}
/**
* @param Job $job
* @return int Seconds for this runner to avoid doing more jobs of this type
* @see $wgJobBackoffThrottling
*/
private function getBackoffTimeToWait( Job $job ) {
$throttling = $this->config->get( 'JobBackoffThrottling' );
if ( !isset( $throttling[$job->getType()] ) || $job instanceof DuplicateJob ) {
return 0; // not throttled
}
$itemsPerSecond = $throttling[$job->getType()];
if ( $itemsPerSecond <= 0 ) {
return 0; // not throttled
}
$seconds = 0;
if ( $job->workItemCount() > 0 ) {
$exactSeconds = $job->workItemCount() / $itemsPerSecond;
// use randomized rounding
$seconds = floor( $exactSeconds );
$remainder = $exactSeconds - $seconds;
$seconds += ( mt_rand() / mt_getrandmax() < $remainder ) ? 1 : 0;
}
return (int)$seconds;
}
/**
* Get the previous backoff expiries from persistent storage
* On I/O or lock acquisition failure this returns the original $backoffs.
*
* @param array $backoffs Map of (job type => UNIX timestamp)
* @param string $mode Lock wait mode - "wait" or "nowait"
* @return array Map of (job type => backoff expiry timestamp)
*/
private function loadBackoffs( array $backoffs, $mode = 'wait' ) {
$file = wfTempDir() . '/mw-runJobs-backoffs.json';
if ( is_file( $file ) ) {
$noblock = ( $mode === 'nowait' ) ? LOCK_NB : 0;
$handle = fopen( $file, 'rb' );
if ( !flock( $handle, LOCK_SH | $noblock ) ) {
fclose( $handle );
return $backoffs; // don't wait on lock
}
$content = stream_get_contents( $handle );
flock( $handle, LOCK_UN );
fclose( $handle );
$ctime = microtime( true );
$cBackoffs = json_decode( $content, true ) ?: [];
foreach ( $cBackoffs as $type => $timestamp ) {
if ( $timestamp < $ctime ) {
unset( $cBackoffs[$type] );
}
}
} else {
$cBackoffs = [];
}
return $cBackoffs;
}
/**
* Merge the current backoff expiries from persistent storage
*
* The $deltas map is set to an empty array on success.
* On I/O or lock acquisition failure this returns the original $backoffs.
*
* @param array $backoffs Map of (job type => UNIX timestamp)
* @param array $deltas Map of (job type => seconds)
* @param string $mode Lock wait mode - "wait" or "nowait"
* @return array The new backoffs account for $backoffs and the latest file data
*/
private function syncBackoffDeltas( array $backoffs, array &$deltas, $mode = 'wait' ) {
if ( !$deltas ) {
return $this->loadBackoffs( $backoffs, $mode );
}
$noblock = ( $mode === 'nowait' ) ? LOCK_NB : 0;
$file = wfTempDir() . '/mw-runJobs-backoffs.json';
$handle = fopen( $file, 'wb+' );
if ( !flock( $handle, LOCK_EX | $noblock ) ) {
fclose( $handle );
return $backoffs; // don't wait on lock
}
$ctime = microtime( true );
$content = stream_get_contents( $handle );
$cBackoffs = json_decode( $content, true ) ?: [];
foreach ( $deltas as $type => $seconds ) {
$cBackoffs[$type] = isset( $cBackoffs[$type] ) && $cBackoffs[$type] >= $ctime
? $cBackoffs[$type] + $seconds
: $ctime + $seconds;
}
foreach ( $cBackoffs as $type => $timestamp ) {
if ( $timestamp < $ctime ) {
unset( $cBackoffs[$type] );
}
}
ftruncate( $handle, 0 );
fwrite( $handle, json_encode( $cBackoffs ) );
flock( $handle, LOCK_UN );
fclose( $handle );
$deltas = [];
return $cBackoffs;
}
/**
* Make sure that this script is not too close to the memory usage limit.
* It is better to die in between jobs than OOM right in the middle of one.
* @return bool
*/
private function checkMemoryOK() {
static $maxBytes = null;
if ( $maxBytes === null ) {
$m = [];
if ( preg_match( '!^(\d+)(k|m|g|)$!i', ini_get( 'memory_limit' ), $m ) ) {
list( , $num, $unit ) = $m;
$conv = [ 'g' => 1073741824, 'm' => 1048576, 'k' => 1024, '' => 1 ];
$maxBytes = $num * $conv[strtolower( $unit )];
} else {
$maxBytes = 0;
}
}
$usedBytes = memory_get_usage();
if ( $maxBytes && $usedBytes >= 0.95 * $maxBytes ) {
$msg = "Detected excessive memory usage ({used_bytes}/{max_bytes}).";
$this->logger->error( $msg, [
'used_bytes' => $usedBytes,
'max_bytes' => $maxBytes,
] );
$msg = "Detected excessive memory usage ($usedBytes/$maxBytes).";
$this->debugCallback( $msg );
return false;
}
return true;
}
/**
* Log the job message
* @param string $msg The message to log
*/
private function debugCallback( $msg ) {
if ( $this->debug ) {
call_user_func_array( $this->debug, [ wfTimestamp( TS_DB ) . " $msg\n" ] );
}
}
/**
* Issue a commit on all masters who are currently in a transaction and have
* made changes to the database. It also supports sometimes waiting for the
* local wiki's replica DBs to catch up. See the documentation for
* $wgJobSerialCommitThreshold for more.
*
* @param LBFactory $lbFactory
* @param Job $job
* @param string $fnameTrxOwner
* @throws DBError
*/
private function commitMasterChanges( LBFactory $lbFactory, Job $job, $fnameTrxOwner ) {
$syncThreshold = $this->config->get( 'JobSerialCommitThreshold' );
$time = false;
$lb = $lbFactory->getMainLB();
if ( $syncThreshold !== false && $lb->getServerCount() > 1 ) {
// Generally, there is one master connection to the local DB
$dbwSerial = $lb->getAnyOpenConnection( $lb->getWriterIndex() );
// We need natively blocking fast locks
if ( $dbwSerial && $dbwSerial->namedLocksEnqueue() ) {
$time = $dbwSerial->pendingWriteQueryDuration( $dbwSerial::ESTIMATE_DB_APPLY );
if ( $time < $syncThreshold ) {
$dbwSerial = false;
}
} else {
$dbwSerial = false;
}
} else {
// There are no replica DBs or writes are all to foreign DB (we don't handle that)
$dbwSerial = false;
}
if ( !$dbwSerial ) {
$lbFactory->commitMasterChanges(
$fnameTrxOwner,
// Abort if any transaction was too big
[ 'maxWriteDuration' => $this->config->get( 'MaxJobDBWriteDuration' ) ]
);
return;
}
$ms = intval( 1000 * $time );
$msg = $job->toString() . " COMMIT ENQUEUED [{job_commit_write_ms}ms of writes]";
$this->logger->info( $msg, [
'job_type' => $job->getType(),
'job_commit_write_ms' => $ms,
] );
$msg = $job->toString() . " COMMIT ENQUEUED [{$ms}ms of writes]";
$this->debugCallback( $msg );
// Wait for an exclusive lock to commit
if ( !$dbwSerial->lock( 'jobrunner-serial-commit', $fnameTrxOwner, 30 ) ) {
// This will trigger a rollback in the main loop
throw new DBError( $dbwSerial, "Timed out waiting on commit queue." );
}
$unlocker = new ScopedCallback( function () use ( $dbwSerial, $fnameTrxOwner ) {
$dbwSerial->unlock( 'jobrunner-serial-commit', $fnameTrxOwner );
} );
// Wait for the replica DBs to catch up
$pos = $lb->getMasterPos();
if ( $pos ) {
$lb->waitForAll( $pos );
}
// Actually commit the DB master changes
$lbFactory->commitMasterChanges(
$fnameTrxOwner,
// Abort if any transaction was too big
[ 'maxWriteDuration' => $this->config->get( 'MaxJobDBWriteDuration' ) ]
);
ScopedCallback::consume( $unlocker );
}
}
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