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https://issues.apache.org/jira/browse/YARN-4963?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15253902#comment-15253902
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Naganarasimha G R commented on YARN-4963:
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Thanks for the clarification [~wangda] & [~nroberts], yes point 2 addresses
the same issue and my mistake i missed to read this. And also agree to the
focus of this jira to be specific to the system level OFF-SWITCH configuration.
bq. so I think when we do the application-level support the default would need
to be either unlimited or some high value, otherwise we force all applications
to set this limit to something other than 1 to get decent OFF_SWITCH scheduling
behavior.
Once we have system level OFF-SWITCH configuration do we require app level
default also ? IIUC by default we try to make use of system level OFF-SWITCH
configuration unless explicitly overridden by the app (implementation can be
further discussed in that jira)
bq. Sure, my application scheduled very quickly but my locality was terrible so
I caused a lot of unnecessary cross-switch traffic. So I think we'll need some
system-minimums that will prevent this type of abuse.
This point is debatable, even though i agree your point for controlling
cross-switch traffic, but still the app is performing under its capacity limits
so would it be good to limit it control it.
bq. If application A meets its OFF-SWITCH-per-node limit, do we offer the node
to other applications in the same queue?
any limitations if we offer the node to other applications in the same queue ?
it should be fine right ?
> capacity scheduler: Make number of OFF_SWITCH assignments per heartbeat
> configurable
> ------------------------------------------------------------------------------------
>
> Key: YARN-4963
> URL: https://issues.apache.org/jira/browse/YARN-4963
> Project: Hadoop YARN
> Issue Type: Improvement
> Components: capacityscheduler
> Affects Versions: 3.0.0, 2.7.2
> Reporter: Nathan Roberts
> Assignee: Nathan Roberts
> Attachments: YARN-4963.001.patch
>
>
> Currently the capacity scheduler will allow exactly 1 OFF_SWITCH assignment
> per heartbeat. With more and more non MapReduce workloads coming along, the
> degree of locality is declining, causing scheduling to be significantly
> slower. It's still important to limit the number of OFF_SWITCH assignments to
> avoid densely packing OFF_SWITCH containers onto nodes.
> Proposal is to add a simple config that makes the number of OFF_SWITCH
> assignments configurable.
> Will upload candidate patch shortly.
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