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Posted to common-issues@hadoop.apache.org by "Amar Kamat (JIRA)" <ji...@apache.org> on 2010/02/09 07:05:29 UTC
[jira] Updated: (HADOOP-2141) speculative execution start up
condition based on completion time
[ https://issues.apache.org/jira/browse/HADOOP-2141?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Amar Kamat updated HADOOP-2141:
-------------------------------
Attachment: hadoop-2141-yahoo-v1.4.8.patch
Attaching a patch for Yahoo!'s distribution of hadoop-0.20 not to be committed.
> speculative execution start up condition based on completion time
> -----------------------------------------------------------------
>
> Key: HADOOP-2141
> URL: https://issues.apache.org/jira/browse/HADOOP-2141
> Project: Hadoop Common
> Issue Type: Improvement
> Affects Versions: 0.21.0
> Reporter: Koji Noguchi
> Assignee: Andy Konwinski
> Fix For: 0.21.0
>
> Attachments: 2141.4.patch, 2141.5.patch, 2141.6.patch, 2141.7.patch, 2141.8.2.patch, 2141.8.3.patch, 2141.patch, HADOOP-2141-v2.patch, HADOOP-2141-v3.patch, HADOOP-2141-v4.patch, HADOOP-2141-v5.patch, HADOOP-2141-v6.patch, hadoop-2141-yahoo-v1.4.1.patch, hadoop-2141-yahoo-v1.4.8.patch, HADOOP-2141.patch, HADOOP-2141.v7.patch, HADOOP-2141.v8.patch
>
>
> We had one job with speculative execution hang.
> 4 reduce tasks were stuck with 95% completion because of a bad disk.
> Devaraj pointed out
> bq . One of the conditions that must be met for launching a speculative instance of a task is that it must be at least 20% behind the average progress, and this is not true here.
> It would be nice if speculative execution also starts up when tasks stop making progress.
> Devaraj suggested
> bq. Maybe, we should introduce a condition for average completion time for tasks in the speculative execution check.
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