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https://issues.apache.org/jira/browse/HADOOP-2108?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Nigel Daley resolved HADOOP-2108.
---------------------------------
Resolution: Duplicate
Fix Version/s: 0.14.3
Duplicate of HADOOP-2036 that was fixed in 0.14.3
> NullPointerException in JVMMetrics for OOM killed task
> ------------------------------------------------------
>
> Key: HADOOP-2108
> URL: https://issues.apache.org/jira/browse/HADOOP-2108
> Project: Hadoop
> Issue Type: Bug
> Components: metrics
> Affects Versions: 0.14.2
> Environment: Centos5 jdk1.6.0_02
> Reporter: Richard Lee
> Priority: Minor
> Fix For: 0.14.3
>
>
> I had a reduce task run out of memory and die in such a way that
> JVMMetrics.doThreadUpdates() throws a NullPointerException.
> The aparent cause seems to be that the call to threadMXBean.getThreadInfo()
> on JVMMetrics:119 returns an array of ThreadInfo whose elements may be null.
> Here's a relevant quote from the javadoc:
> This method returns an array of the ThreadInfo objects,
> * each is the thread information about the thread with the same index
> * as in the ids array.
> * If a thread of the given ID is not alive or does not exist,
> * null will be set in the corresponding element
> * in the returned array. A thread is alive if
> * it has been started and has not yet died.
> My stacktrace looks like this:
> java.lang.NullPointerException
> at
> org.apache.hadoop.metrics.jvm.JvmMetrics.doThreadUpdates(JvmMetrics.java:129)
> at
> org.apache.hadoop.metrics.jvm.JvmMetrics.doUpdates(JvmMetrics.java:79)
> at
> org.apache.hadoop.metrics.spi.AbstractMetricsContext.timerEvent(AbstractMetricsContext.java:284)
> at
> org.apache.hadoop.metrics.spi.AbstractMetricsContext.access$000(AbstractMetricsContext.java:50)
> at
> org.apache.hadoop.metrics.spi.AbstractMetricsContext$1.run(AbstractMetricsContext.java:249)
> at java.util.TimerThread.mainLoop(Timer.java:512)
> at java.util.TimerThread.run(Timer.java:462)
> On line 129, there's an attempt to dereference the potientially null
> threadInfo value to get its current state.
> The naive solution here is to check for null and count null values as
> "terminated"... but it seems clear that a thread state of TERMINATED and a
> null ThreadInfo value are distinct cases and may need special treatment.
> Guessing that this is a "minor" issue because it seems more cosmetic than
> mission critical. I'm not sure what the upstream effects are of this method
> throwing the NPE, so i didn't set it to "trivial".
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