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https://issues.apache.org/jira/browse/HADOOP-5337?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12695427#action_12695427
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Hudson commented on HADOOP-5337:
--------------------------------
Integrated in Hadoop-trunk #796 (See
[http://hudson.zones.apache.org/hudson/job/Hadoop-trunk/796/])
. JobTracker, upon restart, now waits for the TaskTrackers to join back
before scheduling new tasks. This fixes race conditions associated with greedy
scheduling as was the case earlier. Contributed by Amar Kamat.
> JobTracker greedily schedules tasks without running tasks to join
> -----------------------------------------------------------------
>
> Key: HADOOP-5337
> URL: https://issues.apache.org/jira/browse/HADOOP-5337
> Project: Hadoop Core
> Issue Type: Bug
> Components: mapred
> Affects Versions: 0.20.0
> Reporter: Karam Singh
> Assignee: Amar Kamat
> Fix For: 0.20.0
>
> Attachments: HADOOP-5337-v1.11.patch, HADOOP-5337-v1.12.patch,
> HADOOP-5337-v1.7.patch, HADOOP-5337-v1.9.patch
>
>
> This issue was observed when JobTracker was restarted 3 times and observed
> that 4 instances of each reduce task were running. This issue is observed
> when cluster is not fully occupied.
> In testcase: Map/reduces capacity is 200/200 slots respectively and Job
> profile is 11000 maps, 10 reduces and speculative execution is off.
> JobTracker was restarted 3 times in small intervals of about 5 mins and after
> recovery, 40 reduce tasks were running. Task details web page
> (taskdetails.jsp) was showing 4 running attempts of each reduce task.
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