Junping Du created MAPREDUCE-6852:
-------------------------------------
Summary: Job#updateStatus() failed with NPE due to race condition
Key: MAPREDUCE-6852
URL: https://issues.apache.org/jira/browse/MAPREDUCE-6852
Project: Hadoop Map/Reduce
Issue Type: Bug
Reporter: Junping Du
Assignee: Junping Du
Like MAPREDUCE-6762, we found this issue in a cluster where Pig query
occasionally failed on NPE - "Pig uses JobControl API to track MR job status,
but sometimes Job History Server failed to flush job meta files to HDFS which
caused the status update failed." Beside NPE in o.a.h.mapreduce.Job.getJobName,
we also get NPE in Job.updateStatus() and the exception is as following:
{noformat}
Caused by: java.lang.NullPointerException
at org.apache.hadoop.mapreduce.Job$1.run(Job.java:323)
at org.apache.hadoop.mapreduce.Job$1.run(Job.java:320)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:422)
at
org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1833)
at org.apache.hadoop.mapreduce.Job.updateStatus(Job.java:320)
at org.apache.hadoop.mapreduce.Job.isComplete(Job.java:604)
{noformat}
We found state here is null. However, we already check the job state to be
RUNNING as code below:
{noformat}
public boolean isComplete() throws IOException {
ensureState(JobState.RUNNING);
updateStatus();
return status.isJobComplete();
}
{noformat}
The only possible reason here is two threads are calling here for the same
time: ensure state first, then one thread update the state to null while the
other thread hit NPE issue here.
We should fix this NPE exception.
--
This message was sent by Atlassian JIRA
(v6.3.15#6346)
---------------------------------------------------------------------
To unsubscribe, e-mail: mapreduce-issues-unsubscr...@hadoop.apache.org
For additional commands, e-mail: mapreduce-issues-h...@hadoop.apache.org
