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https://issues.apache.org/jira/browse/YARN-8951?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Szilard Nemeth reassigned YARN-8951:
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Assignee: (was: Szilard Nemeth)
> Defining default queue placement rule in allocations file with create="false"
> throws an NPE
> -------------------------------------------------------------------------------------------
>
> Key: YARN-8951
> URL: https://issues.apache.org/jira/browse/YARN-8951
> Project: Hadoop YARN
> Issue Type: Bug
> Reporter: Szilard Nemeth
> Priority: Major
> Attachments: default-placement-rule-with-create-false.patch
>
>
> If the default queue placement rule is defined with {{create="false"}} and a
> scheduling request is created for queue {{"root.default"}}, then
> {{FairScheduler#assignToQueue}} throws an NPE, while trying to construct an
> error message in the catch block of {{IllegalStateException}}, relying on the
> fact that the {{rmApp}} is not null but it is.
> Example of such a config file:
> {code:java}
> <?xml version="1.0"?>
> <allocations>
> <queue name="parentq" type="parent">
> <minResources>1024mb,0vcores</minResources>
> </queue>
> <queuePlacementPolicy>
> <rule name="default" create="false"/>
> </queuePlacementPolicy>
> </allocations>
> {code}
> This is suspicious, as there are some null checks for {{rmApp}} in the same
> method.
> Not sure if this is a special case for the tests or it is reproducable in a
> cluster, this needs further investigation.
> In any case, it's not good that we try to dereference the {{rmApp}} that is
> null.
> On the other hand, I'm not sure if the default queue placement rule with
> {{create="false"}} makes sense at all. Looking at the documentation
> ([https://hadoop.apache.org/docs/r3.1.0/hadoop-yarn/hadoop-yarn-site/FairScheduler.html):]
> {quote}default: the app is placed into the queue specified in the ‘queue’
> attribute of the default rule. *If ‘queue’ attribute is not specified, the
> app is placed into ‘root.default’ queue.*
> A queuePlacementPolicy element: which contains a list of rule elements that
> tell the scheduler how to place incoming apps into queues. Rules are applied
> in the order that they are listed. Rules may take arguments. *All rules
> accept the “create” argument, which indicates whether the rule can create a
> new queue. “Create” defaults to true; if set to false and the rule would
> place the app in a queue that is not configured in the allocations file, we
> continue on to the next rule.* The last rule must be one that can never issue
> a continue....
> {quote}
> In this case, the rule has the queue property suppressed so the apps should
> be placed to the {{root.default}} queue (which is an undefined queue
> according to the config file), and create is false, meaning that the queue
> {{root.default}} cannot be created at all.
> *This seems to be a case of an invalid queue configuration file for me.*
> [~jlowe], [~leftnoteasy]: What is your take on this?
>
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