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https://issues.apache.org/jira/browse/MAPREDUCE-5541?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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zhaoyunjiong updated MAPREDUCE-5541:
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Attachment: MAPREDUCE-5541-branch-1.2.patch
This patch's way to decide whether need a speculative task:
1. The whole job's maps/reduces must already have 80% finished.
2. The task's running time is longer than the average time of finished tasks:
runningTime / 1.5 > avgFinishedTime
I'm still wondering whether should let user decide SPECULATIVE_PROGRESS(80%)
and SPECULATIVE_FACTOR(1.5).
> improved algorithm for whether need speculative task
> ----------------------------------------------------
>
> Key: MAPREDUCE-5541
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-5541
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: mrv1
> Affects Versions: 1.2.1
> Reporter: zhaoyunjiong
> Assignee: zhaoyunjiong
> Fix For: 1.2.2
>
> Attachments: MAPREDUCE-5541-branch-1.2.patch
>
>
> Most of time, tasks won't start running at same time.
> In this case hasSpeculativeTask in TaskInProgress not working very well.
> Some times, some tasks just start running, and scheduler already decide it
> need speculative task to run.
> And this waste a lot of resource.
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