Editing Manual/Job queue (section)

=== Changes in MediaWiki 1.22 === <!--T:30-->
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<translate><!--T:31--> In <tvar name=mw></tvar>, the job queue execution on each page request was changed (<tvar name=gerrit></tvar>) so, instead of executing the job inside the same PHP process that's rendering the page, a new PHP CLI command is spawned to execute <tvar name=runJobs></tvar> in the background.</translate> 
<translate><!--T:32--> It will only work if <tvar name=PhpCli></tvar> is set to an actual path or safe mode is off, otherwise, the old method will be used.</translate>

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This new execution method could cause some problems:

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* If <tvar name=PhpCli></tvar> is set to an incompatible version of PHP (e.g.: an outdated version) jobs may fail to run (fixed in 1.23).</translate>
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* PHP <tvar name=1><code>open_basedir</code></tvar> restrictions are in effect, and <tvar name=PhpCli></tvar> is disallowed (<tvar name=task></tvar>, fixed in 1.23).</translate>
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* Performance: even if the job queue is empty, the new PHP process is started anyway (<tvar name=task></tvar>, fixed in 1.23).</translate>
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* Sometimes the spawning PHP process cause the server or only the CLI process to hang due to <tvar name=1>stdout</tvar> and <tvar name=2>stderr</tvar> descriptors not properly redirected (<tvar name=task></tvar>, fixed in 1.22)</translate>
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* It does not work for shared code (wiki farms), because it doesn't pass additional required parameters to <tvar name=1>runJobs.php</tvar> to identify the wiki that's running the job (<tvar name=task></tvar>, fixed in 1.23)</translate>
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* Normal shell limits like <tvar name=1>, , </tvar> are enforced on the <tvar name=2>runJobs.php</tvar> process that's being executed in the background.
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<translate><!--T:40--> There's no way to revert to the old on-request job queue handling, besides setting <tvar name=PhpCli></tvar> to <tvar name=1><code>false</code></tvar>, for example, which may cause other problems (<tvar name=task></tvar>).</translate> 
<translate><!--T:41--> It can be disabled completely by setting <tvar name=code> 0;}}</tvar>, but jobs will no longer run on page requests, and you must explicitly run <tvar name=1>runJobs.php</tvar> to periodically run pending jobs.</translate>

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