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https://issues.apache.org/jira/browse/HADOOP-153?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12592840#action_12592840
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Doug Cutting commented on HADOOP-153:
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> why not, simply, let the record reader skip the bad record(s) [ ... ] ?

If the record reader can identify bad records and skip them, then the framework 
need not get involved: the RecordReader iteself can catch exceptions that it 
knows might be thrown by bad records and then try to read the next.

> skip records that throw exceptions
> ----------------------------------
>
>                 Key: HADOOP-153
>                 URL: https://issues.apache.org/jira/browse/HADOOP-153
>             Project: Hadoop Core
>          Issue Type: New Feature
>          Components: mapred
>    Affects Versions: 0.2.0
>            Reporter: Doug Cutting
>            Assignee: Devaraj Das
>
> 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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