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https://issues.apache.org/jira/browse/HADOOP-2752?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Nigel Daley updated HADOOP-2752:
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Fix Version/s: (was: 0.16.0)
Removing from 0.16.0 release as this is not a blocker
> ability to configure gap/lag parameters for speculative execution for
> maps/reduces
> ----------------------------------------------------------------------------------
>
> Key: HADOOP-2752
> URL: https://issues.apache.org/jira/browse/HADOOP-2752
> Project: Hadoop Core
> Issue Type: New Feature
> Components: mapred
> Affects Versions: 0.15.3
> Reporter: Joydeep Sen Sarma
>
> Motivation is obvious:
> - sometimes reduces have side-effects - but maps don't (for example reduces
> compute something and write it somewhere)
> - want to turn ON speculative for maps (because maps are usually way less
> expensive. map progress counters are reliable etc.) - but OFF for reduces
> (very expensive to run two reducers instead of one).
> It's also likely that in future you may want different setting for
> speculative triggers for maps and reduces ... (but that's a different issue).
> I will submit a patch (since we are putting this into effect on our cluster -
> and it seems simple enough :-)).
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