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https://issues.apache.org/jira/browse/MAPREDUCE-2108?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12935124#action_12935124
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Scott Chen commented on MAPREDUCE-2108:
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Hey Arun,
Thanks. I have made the first patch.
Like you mentioned, the slot may be used in may places and we need to have a
careful check.
I will read the code more carefully. I have a feeling that there are still
things needs to be changed.
At least in this patch will not change the behavior if we didn't do anything to
the scheduler.
Scott
> Allow TaskScheduler manage number slots on TaskTrackers
> -------------------------------------------------------
>
> Key: MAPREDUCE-2108
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-2108
> Project: Hadoop Map/Reduce
> Issue Type: New Feature
> Components: contrib/capacity-sched, contrib/fair-share
> Affects Versions: 0.22.0
> Reporter: Scott Chen
> Assignee: Scott Chen
> Fix For: 0.22.0
>
> Attachments: MAPREDUCE-2108.txt
>
>
> Currently the map slots and reduce slots are managed by TaskTracker
> configuration.
> To change the task tracker slots, we need to restart the TaskTrackers.
> Also, for a non-uniform cluster, we have to deploy different sets of
> configuration.
> Now JobTracker holds the CPU and memory status of TaskTrackers
> (MAPREDUCE-1218).
> So it makes sense to just let JobTracker.taskScheduler decided the number of
> slots on each node.
> This way we can
> 1. Change the number of slots dynamically without restarting TaskTracker
> 2. Use different number of slots based on the resource of a TaskTracker
> To achieve this, we need to change the logic that we use totalMapSlots and
> totalReduceSlots in JobTracker.
> I think they are used in WebUI and speculativeCap.
> We will need to make JobTracker calculate these numbers from TaskScheduler
> and TaskTrackerStatus.
> TaskScheduler and TaskTracker can both hold their maximum slots. We pick the
> smaller one.
> Thoughts?
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