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Tsuyoshi Ozawa commented on MAPREDUCE-6361: ------------------------------------------- +1, I confirmed that this is a bug about concurrency between threads of Fether#run as Junping mentioned. Committing this shortly. > NPE issue in shuffle caused by concurrent issue between copySucceeded() in > one thread and copyFailed() in another thread on the same host > ----------------------------------------------------------------------------------------------------------------------------------------- > > Key: MAPREDUCE-6361 > URL: https://issues.apache.org/jira/browse/MAPREDUCE-6361 > Project: Hadoop Map/Reduce > Issue Type: Bug > Reporter: Junping Du > Assignee: Junping Du > Priority: Critical > Attachments: MAPREDUCE-6361-v1.patch > > > The failure in log: > 2015-05-08 21:00:00,513 WARN [main] org.apache.hadoop.mapred.YarnChild: > Exception running child : > org.apache.hadoop.mapreduce.task.reduce.Shuffle$ShuffleError: error in > shuffle in fetcher#25 > at > org.apache.hadoop.mapreduce.task.reduce.Shuffle.run(Shuffle.java:134) > at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:376) > at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:163) > at java.security.AccessController.doPrivileged(Native Method) > at javax.security.auth.Subject.doAs(Subject.java:415) > at > org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1628) > at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:158) > Caused by: java.lang.NullPointerException > at > org.apache.hadoop.mapreduce.task.reduce.ShuffleSchedulerImpl.copyFailed(ShuffleSchedulerImpl.java:267) > at > org.apache.hadoop.mapreduce.task.reduce.Fetcher.copyFromHost(Fetcher.java:308) > at > org.apache.hadoop.mapreduce.task.reduce.Fetcher.run(Fetcher.java:193) -- This message was sent by Atlassian JIRA (v6.3.4#6332)