ninjapenguin ninjapenguin - 29 days ago 6
PHP Question

Detecting no available server with PHP and Gearman

I'm currently making use of Gearman with PHP using the standard bindings (docs here). All functioning fine, but I have one small issue with not being able to detect when a call to GearmanClient::addServer (docs here) is "successfull", by which I mean...

The issue is that adding the server attempts no socket I/O, meaning that the server may not actually exist or be operational. This means that subsequent code calls (in the scenario where the sever does not infact exist) fail and result in PHP warnings

Is there any way, or what is the best way, to confirm that the Gearman Daemon is operational on the server before or after adding it?

I would like to achieve this so that I can reliably handle scenarios in which Gearman may have died, or the server is un-contactable perhaps..

Many thanks.

Answer

We first tried this by manually calling fsockopen on the host and port passed to addServer, but it turns out that this can leave a lot of hanging connections as the Gearman server expects something to happen over that socket.

We use a monitor script to check the status of the daemon and its workers — something similar to this perl script on Google Groups. We modified the script to restart the daemon if it was not running.

If this does not appeal, have a look at the Gearman Protocol (specifically the “Administrative Protocol” section, referenced in the above thread) and use the status command. This will give you information on the status of the jobs and workers, but also means you can perform a socket connection to the daemon and not leave it hanging.

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