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Posted to common-dev@hadoop.apache.org by "Doug Cutting (JIRA)" <ji...@apache.org> on 2006/05/01 19:43:48 UTC

[jira] Updated: (HADOOP-156) Reducer threw IOEOFException

     [ http://issues.apache.org/jira/browse/HADOOP-156?page=all ]

Doug Cutting updated HADOOP-156:
--------------------------------

    Component: mapred

> Reducer  threw IOEOFException
> -----------------------------
>
>          Key: HADOOP-156
>          URL: http://issues.apache.org/jira/browse/HADOOP-156
>      Project: Hadoop
>         Type: Bug

>   Components: mapred
>     Reporter: Runping Qi

>
> A job was running with all the map tasks completed.
> The reducers were appending the intermediate files into the large intermediate file.
> java.io.EOFException was thrown when the record reader tried to read the version number
> during initialization. Here is the stack trace:
> java.io.EOFException 
>     at java.io.DataInputStream.readFully(DataInputStream.java:178) 
>     at java.io.DataInputStream.readFully(DataInputStream.java:152) 
>     at org.apache.hadoop.io.SequenceFile$Reader.init(SequenceFile.java:251) 
>     at org.apache.hadoop.io.SequenceFile$Reader.(SequenceFile.java:236) 
>     at org.apache.hadoop.io.SequenceFile$Reader.(SequenceFile.java:226) 
>     at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:205) 
>     at org.apache.hadoop.mapred.TaskTracker$Child.main(TaskTracker.java:709) 
> Appearantly, the intermediate file was empty. I suspect that one map task
> generated empty intermidiate files for all the reducers, since all the reducers
> failed at the same place, and failed at the same place during retries.
> Unfortunately, we cannot know which map task generated the empty files,
> since the exception does not offer any clue.
> One simple enhancement is that the record reader should catch IOException and re-throw it with additional 
> information, such as the file name.

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