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https://issues.apache.org/jira/browse/HADOOP-3117?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12583562#action_12583562
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Devaraj Das commented on HADOOP-3117:
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As per the trunk, there are two switches for controlling speculative execution
- mapred.{map,reduce}.tasks.speculative.execution. The default value is true
for both.
The corresponding JobConf APIs are setMapSpeculativeExecution(boolean) &
setReduceSpeculativeExecution(boolean)
There is a third API - setSpeculativeExecution(boolean). This sets true or
false for both types of tasks. (Pls see HADOOP-2819).
>From the config point of view, having two distinct knobs for maps and reduces
>makes things more clear, no?
> Speculative execution configuration is confusing
> ------------------------------------------------
>
> Key: HADOOP-3117
> URL: https://issues.apache.org/jira/browse/HADOOP-3117
> Project: Hadoop Core
> Issue Type: Improvement
> Components: conf
> Affects Versions: 0.16.0
> Reporter: Sameer Paranjpye
> Assignee: Devaraj Das
> Fix For: 0.17.0
>
>
> In Hadoop 0.16 the single switch for speculative execution was replaced by 2
> switches for maps and reduces. The old switch was retained as well and
> overrides the new switches if it is turned on. This is confusing. We should
> go back to a single config variable that has one value from the set --
> 'true, false, map, reduce'.
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