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https://issues.apache.org/jira/browse/YARN-5829?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15926921#comment-15926921
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ASF GitHub Bot commented on YARN-5829:
--------------------------------------
Github user szegedim commented on a diff in the pull request:
https://github.com/apache/hadoop/pull/201#discussion_r106274089
--- Diff:
hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FSAppAttempt.java
---
@@ -831,7 +831,11 @@ private Resource assignContainer(
}
// The desired container won't fit here, so reserve
- if (isReservable(capability) &&
+ // Important: Do not enable this kind of reservation in case of
preemption,
+ // since the preempted application will re-reserve the preempted
resources
+ // and prevent the starving application to get them
+ if (!scheduler.getConf().getPreemptionEnabled() &&
--- End diff --
I improved this by giving higher priority to preempted containers than
reservation. Child queues may pass containers to each other this way resolving
fairness starvation. Please review the updated change.
> FS preemption should reserve a node before considering containers on it for
> preemption
> --------------------------------------------------------------------------------------
>
> Key: YARN-5829
> URL: https://issues.apache.org/jira/browse/YARN-5829
> Project: Hadoop YARN
> Issue Type: Sub-task
> Components: fairscheduler
> Reporter: Karthik Kambatla
> Assignee: Miklos Szegedi
>
> FS preemption evaluates nodes for preemption, and subsequently preempts
> identified containers. If this node is not reserved for a specific
> application, any other application could be allocated resources on this node.
> Reserving the node for the starved application before preempting containers
> would help avoid this.
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