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From "Peng Zhang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-6302) deadlock in a job between map and reduce cores allocation
Date Wed, 15 Apr 2015 05:52:59 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-6302?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14495699#comment-14495699
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Peng Zhang commented on MAPREDUCE-6302:
---------------------------------------

in head log it shows 
Number of reduces for job job_1427451307913_0012 = 380

in tail log it shows 
headroom=<memory:333824, vCores:661> and totalResourceLimit:<memory:667648, vCores:824>

It seems conflict with statement “as long as reduces of a job is more than max cores of
the queue , deadlock always happened. ”

> deadlock in a job between map and reduce cores allocation 
> ----------------------------------------------------------
>
>                 Key: MAPREDUCE-6302
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-6302
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>    Affects Versions: 2.6.0
>            Reporter: mai shurong
>            Assignee: Karthik Kambatla
>            Priority: Critical
>         Attachments: AM_log_head100000.txt.gz, AM_log_tail100000.txt.gz, queue_with_max163cores.png,
queue_with_max263cores.png, queue_with_max333cores.png
>
>
> I submit a  big job, which has 500 maps and 350 reduce, to a queue(fairscheduler) with
300 max cores. When the big mapreduce job is running 100% maps, the 300 reduces have occupied
300 max cores in the queue. And then, a map fails and retry, waiting for a core, while the
300 reduces are waiting for failed map to finish. So a deadlock occur. As a result, the job
is blocked, and the later job in the queue cannot run because no available cores in the queue.
> I think there is the similar issue for memory of a queue .



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