[jira] Commented: (HADOOP-153) skip records that throw exceptions

["Sameer Paranjpye (JIRA)" <ji...@apache.org>]

    [ http://issues.apache.org/jira/browse/HADOOP-153?page=comments#action_12375405 ] 

Sameer Paranjpye commented on HADOOP-153:
-----------------------------------------

+1

This would be a cool feature to have. Perhaps the exceptions should also be made visible at the jobtracker. An extension to manage exceptions in RecordWriter.write() could record the offending key(s) and skip them the next time the task is run.

> skip records that throw exceptions
> ----------------------------------
>
>          Key: HADOOP-153
>          URL: http://issues.apache.org/jira/browse/HADOOP-153
>      Project: Hadoop
>         Type: New Feature

>   Components: mapred
>     Reporter: Doug Cutting

>
> MapReduce should skip records that throw exceptions.
> If the exception is thrown under RecordReader.next() then RecordReader implementations should automatically skip to the start of a subsequent record.
> Exceptions in map and reduce implementations can simply be logged, unless they happen under RecordWriter.write().  Cancelling partial output could be hard.  So such output errors will still result in task failure.
> This behaviour should be optional, but enabled by default.  A count of errors per task and job should be maintained and displayed in the web ui.  Perhaps if some percentage of records (>50%?) result in exceptions then the task should fail.  This would stop jobs early that are misconfigured or have buggy code.
> Thoughts?

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