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From "Runping Qi (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-153) skip records that throw exceptions
Date Tue, 06 May 2008 14:12:55 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-153?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12594591#action_12594591
] 

Runping Qi commented on HADOOP-153:
-----------------------------------


Regarding skipping records wrt streaming and pipe: 
When a task is re-executed, it can skip N records starting at the detected fail position and
processes the rest.
At the end, the tasl can process thos N skipped records on a "best-effort" basis.




> 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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