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https://issues.apache.org/jira/browse/MAPREDUCE-1608?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12932589#action_12932589
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Hong Tang commented on MAPREDUCE-1608:
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bq. How do you prevent devious/malicious users from speculating on all their
tasks via a simple shell script?
This is an orthogonal issue. An easy solution would be to set an upper limit of
how many tasks that one can speculate manually, e.g. 1% of total {map|reduce}
tasks.
> Allow users to do speculative execution of a task manually
> ----------------------------------------------------------
>
> Key: MAPREDUCE-1608
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-1608
> Project: Hadoop Map/Reduce
> Issue Type: New Feature
> Reporter: Scott Chen
> Assignee: Scott Chen
>
> Speculative execution improves the latency of the job. Sometimes the job has
> few very slow reducers. Spending a little more resource on speculative tasks
> can improve the latency a lot. It will be nice that the users can manually
> select one task and force the speculative execution on that task just like we
> can manually kill/fail task.
> The proposal is add link says "speculate" in taskdetails.jsp page where we do
> "kill/fail".
> Thoughts?
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