[MAPREDUCE-4030] If the nodemanager on which the maptask is executed is going down before the mapoutput is consumed by the reducer,then the job is failing with shuffle error

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Not A Problem
• Component/s: mrv2
• Target Version/s: 0.23.3, 2.0.0-alpha
• Assignee: Unassigned
• Reporter: Nishan Shetty
• Created: 19/Mar/12 05:42
• Updated: 30/May/12 11:14
• Resolved: 30/May/12 11:14

Description

My cluster has 2 NM's.
The value of "mapreduce.job.reduce.slowstart.completedmaps" is set to 1.
When the job execution is in progress and Mappers has finished about 99% completion,one of the NM has gone down.
The job has failed with the following trace

"Error: org.apache.hadoop.mapreduce.task.reduce.Shuffle$ShuffleError: error in shuffle in fetcher#1 at org.apache.hadoop.mapreduce.task.reduce.Shuffle.run(Shuffle.java:123) at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:371) at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:148) at java.security.AccessController.doPrivileged(Native Method) at javax.security.auth.Subject.doAs(Subject.java:396) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1177) at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:143) Caused by: java.io.IOException: Exceeded MAX_FAILED_UNIQUE_FETCHES; bailing-out. at org.apache.hadoop.mapreduce.task.reduce.ShuffleScheduler.checkReducerHealth(ShuffleScheduler.java:253) at org.apache.hadoop.mapreduce.task.reduce.ShuffleScheduler.copyFailed(ShuffleScheduler.java:187) at org.apache.hadoop.mapreduce.task.reduce.Fetcher.copyFromHost(Fetcher.java:240) at org.apache.hadoop.mapreduce.task.reduce.Fetcher.run(Fetcher.java:152) "