NullPointerException is coming in the job tracker when job tracker resends the
previous heartbeat response.
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Key: MAPREDUCE-2464
URL: https://issues.apache.org/jira/browse/MAPREDUCE-2464
Project: Hadoop Map/Reduce
Issue Type: Bug
Components: jobtracker
Affects Versions: 0.23.0
Reporter: Devaraj K
Assignee: Devaraj K
Over the network, the heartbeat response sent by Job Tracker to Task Tracker
might get lost. When Task Tracker sends the old heart beat again to Job Tracker
then Job Tracker finds and ignores it saying duplicate and resends the old
heartbeat response which it is maintaining in a map. If the response contains
LaunchTaskAction for MapTask, then the NullPointerException is throwing.
{code:xml}
2011-05-02 16:01:53,148 INFO org.apache.hadoop.ipc.Server: IPC Server handler 1
on 9001 caught: java.lang.NullPointerException
at org.apache.hadoop.mapred.MapTask.write(MapTask.java:140)
at
org.apache.hadoop.mapred.LaunchTaskAction.write(LaunchTaskAction.java:48)
at
org.apache.hadoop.mapred.HeartbeatResponse.write(HeartbeatResponse.java:91)
at
org.apache.hadoop.io.ObjectWritable.writeObject(ObjectWritable.java:163)
at org.apache.hadoop.io.ObjectWritable.write(ObjectWritable.java:74)
at org.apache.hadoop.ipc.Server.setupResponse(Server.java:1561)
at org.apache.hadoop.ipc.Server.access$2800(Server.java:96)
at org.apache.hadoop.ipc.Server$Handler.run(Server.java:1433)
{code}
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