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https://issues.apache.org/jira/browse/YARN-7051?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Eric Payne updated YARN-7051:
-----------------------------
Attachment: YARN-7051.002.patch
bq. so this won't be changing while createTempAppForResCalculation is looping
over the list.
However, I did find a race condition that throws an NPE within
{{createTempAppForResCalculation}}.
{noformat}
java.lang.NullPointerException
at
org.apache.hadoop.yarn.util.resource.Resources.clone(Resources.java:155)
at
org.apache.hadoop.yarn.server.resourcemanager.monitor.capacity.FifoIntraQueuePreemptionPlugin.createTempAppForResCalculation(FifoIntraQueuePreemptionPlugin.java:403)
at
org.apache.hadoop.yarn.server.resourcemanager.monitor.capacity.FifoIntraQueuePreemptionPlugin.computeAppsIdealAllocation(FifoIntraQueuePreemptionPlugin.java:140)
at
org.apache.hadoop.yarn.server.resourcemanager.monitor.capacity.IntraQueueCandidatesSelector.computeIntraQueuePreemptionDemand(IntraQueueCandidatesSelector.java:283)
{noformat}
The reason for this is that {{perUserAMUsed}} was populated with running apps
prior to calling {{createTempAppForResCalculation}}, but then
{{createTempAppForResCalculation}} loops through both running and pending apps.
Attaching new patch that addresses this.
> FifoIntraQueuePreemptionPlugin can get concurrent modification exception
> ------------------------------------------------------------------------
>
> Key: YARN-7051
> URL: https://issues.apache.org/jira/browse/YARN-7051
> Project: Hadoop YARN
> Issue Type: Bug
> Components: capacity scheduler, scheduler preemption, yarn
> Affects Versions: 2.9.0, 2.8.1, 3.0.0-alpha3
> Reporter: Eric Payne
> Assignee: Eric Payne
> Priority: Critical
> Attachments: YARN-7051.001.patch, YARN-7051.002.patch
>
>
> {{FifoIntraQueuePreemptionPlugin#calculateUsedAMResourcesPerQueue}} has the
> following code:
> {code}
> Collection<FiCaSchedulerApp> runningApps = leafQueue.getApplications();
> Resource amUsed = Resources.createResource(0, 0);
> for (FiCaSchedulerApp app : runningApps) {
> {code}
> {{runningApps}} is unmodifiable but not concurrent. This caused the
> preemption monitor thread to crash in the RM in one of our clusters.
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