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From "Hemanth Yamijala (JIRA)" <j...@apache.org>
Subject [jira] Commented: (MAPREDUCE-1695) capacity scheduler is not included in findbugs/javadoc targets
Date Wed, 21 Apr 2010 09:06:50 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-1695?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12859260#action_12859260

Hemanth Yamijala commented on MAPREDUCE-1695:

Hong, this approach introduces a coarse locking of the scheduler. It is imaginable that schedulers
can implement lazy refreshing options - for e.g. let the current scheduling operation complete
before picking up the refreshed configuration. For such cases, the current approach is imposing
a locking constraint that circumvents any such optimization. (In fact, digging further, I
actually see we are already locking the scheduler in initializeQueues when we want to switch
the queue hierarchy - hence we already have the inverse locking issue even without this patch
- but for the same reason I explained before, it probably still works). 

That said, I am not fully convinced this is a bad idea. On the one hand, the simplicity of
this approach is appealing. On the other, the effects of a coarse locking have bitten us hard
before, as you are well aware. So, I am just a little wary.

Thoughts ? Opinion from others ?

> capacity scheduler is not included in findbugs/javadoc targets
> --------------------------------------------------------------
>                 Key: MAPREDUCE-1695
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1695
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: contrib/capacity-sched
>            Reporter: Hong Tang
>            Assignee: Hong Tang
>         Attachments: MAPREDUCE-1695-2.patch, mapreduce-1695-20100420-2.patch, mapreduce-1695-20100420.patch,
mapreduce-1695-20100421.patch, MAPREDUCE-1695-3.patch, MAPREDUCE-1695.patch, mr1695-hadoop-findbugs-report-1.html,
> Capacity Scheduler is not included in findbugs/javadoc targets.

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