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https://issues.apache.org/jira/browse/HADOOP-2141?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12567071#action_12567071
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Amar Kamat commented on HADOOP-2141:
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Dumping some logs from my recent runs
{noformat}
2008-02-08 15:09:19,459 INFO org.apache.hadoop.mapred.TaskInProgress: Error
from task_200802080908_0005_r_001459_0: Task task_200802080908_0005_r_001459_0
failed to report status for 605 seconds. Killing!
2008-02-08 15:09:19,460 INFO org.apache.hadoop.mapred.JobTracker: Removed
completed task 'task_200802080908_0005_r_001459_0' from
'tracker_gs205019.inktomisearch.com:gs205019.inktomisearch.com/76.13.184.103:58495'
2008-02-08 15:09:19,474 INFO org.apache.hadoop.mapred.TaskRunner: Discarded
output of task 'task_200802080908_0005_r_001459_0' -
hdfs://gs205514.inktomisearch.com:57972/user/amarrk/output/_task_200802080908_0005_r_001459_0
2008-02-08 15:09:19,513 INFO org.apache.hadoop.mapred.JobInProgress: Choosing
normal task tip_200802080908_0005_r_001459
2008-02-08 15:09:19,514 INFO org.apache.hadoop.mapred.JobTracker: Adding task
'task_200802080908_0005_r_001459_1' to tip tip_200802080908_0005_r_001459, for
tracker
'tracker_gs205440.inktomisearch.com:gs205440.inktomisearch.com/76.13.187.49:55843'
2008-02-08 15:09:19,517 INFO org.apache.hadoop.mapred.JobInProgress: Choosing
speculative task tip_200802080908_0005_r_001459
2008-02-08 15:09:19,517 INFO org.apache.hadoop.mapred.JobTracker: Adding task
'task_200802080908_0005_r_001459_2' to tip tip_200802080908_0005_r_001459, for
tracker
'tracker_gs205190.inktomisearch.com:gs205190.inktomisearch.com/76.13.185.109:58837'
{noformat}
The main task and speculative one got executed back to back.
> speculative execution start up condition based on completion time
> -----------------------------------------------------------------
>
> Key: HADOOP-2141
> URL: https://issues.apache.org/jira/browse/HADOOP-2141
> Project: Hadoop Core
> Issue Type: Improvement
> Components: mapred
> Affects Versions: 0.15.0
> Reporter: Koji Noguchi
> Assignee: Arun C Murthy
> Fix For: 0.17.0
>
>
> 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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