Scheduler within cluster environment [WAS: Re: [Yanel-dev] First Scheduler implementation finished]

Michael Wechner michael.wechner at wyona.com
Wed Feb 3 10:32:28 CET 2010


Hi

I have just noticed we have got a problem if the scheduler is enabled 
within a cluster environment, because
jobs configured via

src/realms/from-scratch-realm-template/data-repo/data/scheduler-jobs.xml

would be read by each cluster node where the scheduler is enabled and 
hence the same job
would be executed by each cluster node, which does not make sense 
"performance" wise, but
also can lead to writing problems.

One way of dealing with this would be that the cluster node which reads 
first will add a flag to this job
that it already takes care of it and hence no other cluster node has to 
deal with it, but this can lead
to problems if a cluster node crashes or is being removed.

I think others have similar problems, e.g.

http://publib.boulder.ibm.com/infocenter/wasinfo/v6r0/index.jsp?topic=/com.ibm.websphere.express.doc/info/exp/scheduler/ref/rsch_changes.html

Any pointers to how to solve this best are very much appreciated.

Thanks

Michi

Michael Wechner wrote:
> Hi
>
> I have finished a first scheduler implementation which is based on the 
> quartz scheduler. The goal is to make
> it independent of the actual scheduler implementation, but to gain 
> some experience I think it's alright for the moment.
>
> There is no GUI yet, but one can schedule jobs for each realm, e.g.
>
> src/realms/from-scratch-realm-template/data-repo/data/scheduler-jobs.xml
>
> which means these config files are being read during startup.
>
> So far it seems to work very fine. The next step would be to introduce 
> interfaces to hide
> the implementations details.
>
> Then we should think about a GUI such that people can schedule jobs 
> like for example schedule the publishing
> of an article and also about persistance of these jobs, which  means 
> in case the Webapp-server should crash or shutdown
> for maintenance.
>
> Cheers
>
> Michi



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