[ 
https://issues.apache.org/jira/browse/YARN-6956?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Steven Rand updated YARN-6956:
------------------------------
    Description: 
I'm observing the following series of events on a CDH 5.11.0 cluster, which 
seem to be possible after https://issues.apache.org/jira/browse/YARN-6163:

1. An application is considered to be starved, so {{FSPreemptionThread}} calls 
{{identifyContainersToPreempt}}, and that calls 
{{FSAppAttempt#getStarvedResourceRequests}} to get a list of 
{{ResourceRequest}} instances that are enough to address the app's starvation.

2. The first {{ResourceRequest}} that {{getStarvedResourceRequests}} sees is 
enough to address the app's starvation, so we break out of the loop over 
{{appSchedulingInfo.getAllResourceRequests()}} after only one iteration: 
https://github.com/apache/hadoop/blob/trunk/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#L1180.
 We return only this one {{ResourceRequest}} back to the 
{{identifyContainersToPreempt}} method.

3. It turns out that this particular {{ResourceRequest}} happens to have a 
value for {{getResourceName}} that identifies a specific node in the cluster. 
This causes preemption to only consider containers on that node, and not the 
rest of the cluster.

[~kasha], does that make sense? I'm happy to submit a patch if I'm 
understanding the problem correctly.

  was:
I'm observing the following series of events on a CDH 5.11.0 cluster, which 
seem to be possible after https://issues.apache.org/jira/browse/YARN-6163:

1. An application is considered to be starved, so {{FSPreemptionThread}} calls 
{{identifyContainersToPreempt}}, and that calls 
{{FSAppAttempt#getStarvedResourceRequests}} to get a list of 
{{ResourceRequest}} instances that are enough to address the app's starvation.

2. The first {{ResourceRequest}} that {{getStarvedResourceRequests}} sees is 
enough to address the app's starvation, so we break out of the loop over 
{{appSchedulingInfo.getAllResourceRequests()}} after only one iteration: 
https://github.com/apache/hadoop/blob/trunk/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#L1180.
 We return only this one {{ResourceRequest}} back to the 
{{identifyContainersToPreempt}} method.

3. It turns out that this particular {{ResourceRequest}} happens to have a 
value for {{getResourceName}} that identifies a specific node in the cluster. 
This cause preemption to only consider containers on that node, and not the 
rest of the cluster.

[~kasha], does that make sense? I'm happy to submit a patch if I'm 
understanding the problem correctly.


> preemption may only consider resource requests for one node
> -----------------------------------------------------------
>
>                 Key: YARN-6956
>                 URL: https://issues.apache.org/jira/browse/YARN-6956
>             Project: Hadoop YARN
>          Issue Type: Bug
>          Components: fairscheduler
>    Affects Versions: 2.9.0, 3.0.0-beta1
>         Environment: CDH 5.11.0
>            Reporter: Steven Rand
>
> I'm observing the following series of events on a CDH 5.11.0 cluster, which 
> seem to be possible after https://issues.apache.org/jira/browse/YARN-6163:
> 1. An application is considered to be starved, so {{FSPreemptionThread}} 
> calls {{identifyContainersToPreempt}}, and that calls 
> {{FSAppAttempt#getStarvedResourceRequests}} to get a list of 
> {{ResourceRequest}} instances that are enough to address the app's starvation.
> 2. The first {{ResourceRequest}} that {{getStarvedResourceRequests}} sees is 
> enough to address the app's starvation, so we break out of the loop over 
> {{appSchedulingInfo.getAllResourceRequests()}} after only one iteration: 
> https://github.com/apache/hadoop/blob/trunk/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#L1180.
>  We return only this one {{ResourceRequest}} back to the 
> {{identifyContainersToPreempt}} method.
> 3. It turns out that this particular {{ResourceRequest}} happens to have a 
> value for {{getResourceName}} that identifies a specific node in the cluster. 
> This causes preemption to only consider containers on that node, and not the 
> rest of the cluster.
> [~kasha], does that make sense? I'm happy to submit a patch if I'm 
> understanding the problem correctly.



--
This message was sent by Atlassian JIRA
(v6.4.14#64029)

---------------------------------------------------------------------
To unsubscribe, e-mail: yarn-issues-unsubscr...@hadoop.apache.org
For additional commands, e-mail: yarn-issues-h...@hadoop.apache.org

Reply via email to