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Posted to mapreduce-issues@hadoop.apache.org by "Vinod Kumar Vavilapalli (Assigned) (JIRA)" <ji...@apache.org> on 2011/10/20 08:39:10 UTC

[jira] [Assigned] (MAPREDUCE-3226) Few reduce tasks hanging in a gridmix-run

     [ https://issues.apache.org/jira/browse/MAPREDUCE-3226?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Vinod Kumar Vavilapalli reassigned MAPREDUCE-3226:
--------------------------------------------------

    Assignee: Vinod Kumar Vavilapalli
    
> Few reduce tasks hanging in a gridmix-run
> -----------------------------------------
>
>                 Key: MAPREDUCE-3226
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-3226
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: mrv2, task
>    Affects Versions: 0.23.0
>            Reporter: Vinod Kumar Vavilapalli
>            Assignee: Vinod Kumar Vavilapalli
>            Priority: Blocker
>             Fix For: 0.23.0
>
>
> In a gridmix run with ~1000 jobs, one job is getting stuck because of 2-3 hanging reducers. All of the them are stuck after downloading all map outputs and have the following thread dump.
> {code}
> "EventFetcher for fetching Map Completion Events" daemon prio=10 tid=0xa325fc00 nid=0x1ca4 waiting on condition [0xa315c000]
>    java.lang.Thread.State: TIMED_WAITING (sleeping)
>         at java.lang.Thread.sleep(Native Method)
>         at org.apache.hadoop.mapreduce.task.reduce.EventFetcher.run(EventFetcher.java:71)
> "main" prio=10 tid=0x080ed400 nid=0x1c71 in Object.wait() [0xf73a2000]
>    java.lang.Thread.State: WAITING (on object monitor)
>         at java.lang.Object.wait(Native Method)
>         - waiting on <0xa94b23d8> (a org.apache.hadoop.mapreduce.task.reduce.EventFetcher)
>         at java.lang.Thread.join(Thread.java:1143)
>         - locked <0xa94b23d8> (a org.apache.hadoop.mapreduce.task.reduce.EventFetcher)
>         at java.lang.Thread.join(Thread.java:1196)
>         at org.apache.hadoop.mapreduce.task.reduce.Shuffle.run(Shuffle.java:135)
>         at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:367)
>         at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:147)
>         at java.security.AccessController.doPrivileged(Native Method)
>         at javax.security.auth.Subject.doAs(Subject.java:396)
>         at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1135)
>         at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:142)
> {code}
> Thanks to [~karams] for helping track this down.

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