[Swift-user] Swift scheduler

[Ben Clifford]

On Fri, 1 Aug 2008, Andriy Fedorov wrote:

> For example, suppose I have an application, which has multiple
> mappings to different remote sites. How is the submission site going
> to be selected? 

Each site has a score which reflects how many jobs will be sent to that 
site at once. The score goes up as the site is used successfully and goes 
down as there are problems with the site.

When its time to submit a job, one of the sites which has free space 
(score - actual load) will get the job.

> In case I have long queueing delays on the selected site, can Swift 
> detect that, and submit job to a different site?

yes. In recent trunk code there is a feature called 'replication' whereby 
jobs will be submitted to up to two (three?) more times if they take more 
than three times the average time for jobs. Look in swift.proeprties for 
the three replication.* properties.

In the past we've discussed more complicated selection algorithms than 3 * 
mean.

> Can any of the developers point me to the specific part of the source
> that is responsible for scheduling, so that I could try to figure this
> out myself?

Start here:

cog/modules/karajan/src/org/globus/cog/karajan/scheduler/WeightedHostScoreScheduler.java.

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