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https://issues.apache.org/jira/browse/MAPREDUCE-4233?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13272785#comment-13272785
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Robert Joseph Evans commented on MAPREDUCE-4233:
------------------------------------------------
Ahmed,
We were using the capacity scheduler at the time.
I debated how I should special case this, and I am fine changing it so let me
know if you feel strongly about it.
I thought about simply returning a 0 for NumContainers, UsedMemoryMB and
AvailableMemoryMB, because that is what the true values are. no containers are
running using no memory and because the node is unavailable there is no
available memory. This is what the web service at /ws/v1/cluster/nodes does
for these values, but I thought not having them there was a better flag to
indicate that something was wrong with the node. I don't really want to return
something like
{code}
{
...
"NumContainers" : "Scheduler report unavailable",
...
}
{code}
Because they normally return numbers and it doesn't really feel right to me to
return a string when we normally return a number, but returning a -1 as a flag
also doesn't feel quite right.
> NPE can happen in RMNMNodeInfo.
> -------------------------------
>
> Key: MAPREDUCE-4233
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-4233
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Affects Versions: 0.23.3
> Reporter: Robert Joseph Evans
> Assignee: Robert Joseph Evans
> Priority: Critical
> Attachments: MR-4233.txt
>
>
> {noformat}
> Caused by: java.lang.NullPointerException
> at
> org.apache.hadoop.yarn.server.resourcemanager.RMNMInfo.getLiveNodeManagers(RMNMInfo.java:96)
> at sun.reflect.GeneratedMethodAccessor50.invoke(Unknown Source)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
> at java.lang.reflect.Method.invoke(Method.java:597)
> at
> com.sun.jmx.mbeanserver.StandardMBeanIntrospector.invokeM2(StandardMBeanIntrospector.java:93)
> at
> com.sun.jmx.mbeanserver.StandardMBeanIntrospector.invokeM2(StandardMBeanIntrospector.java:27)
> at
> com.sun.jmx.mbeanserver.MBeanIntrospector.invokeM(MBeanIntrospector.java:208)
> at
> com.sun.jmx.mbeanserver.PerInterface.getAttribute(PerInterface.java:65)
> at
> com.sun.jmx.mbeanserver.MBeanSupport.getAttribute(MBeanSupport.java:216)
> at javax.management.StandardMBean.getAttribute(StandardMBean.java:358)
> at
> com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.getAttribute(DefaultMBeanServerInterceptor.java:666)
> {noformat}
> Looks like rmcontext.getRMNodes() is not kept in sync with
> scheduler.getNodeReport(), so that the report can be null even though the
> context still knowns about the node.
> The simple fix is to add in a null check.
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