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Posted to common-dev@hadoop.apache.org by "Christian Kunz (JIRA)" <ji...@apache.org> on 2007/09/11 07:31:32 UTC

[jira] Commented: (HADOOP-1874) lost task trackers -- jobs hang

    [ https://issues.apache.org/jira/browse/HADOOP-1874?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12526352 ] 

Christian Kunz commented on HADOOP-1874:
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Forgot to mention that with so many lost task trackers we run into HADOOP-1862, with the consequence that the job does not make any progress.

> lost task trackers -- jobs hang
> -------------------------------
>
>                 Key: HADOOP-1874
>                 URL: https://issues.apache.org/jira/browse/HADOOP-1874
>             Project: Hadoop
>          Issue Type: Bug
>          Components: mapred
>    Affects Versions: 0.15.0
>            Reporter: Christian Kunz
>            Priority: Blocker
>
> This happens on a 1400 node cluster using a recent nightly build patched with HADOOP-1763 (that fixes a previous 'lost task tracker' issue) running a c++-pipes job with 4200 maps and 2800 reduces. The task trackers start to get lost in high numbers at the end of job completion.
> Similar non-pipes job do not show the same problem, but is unclear whether it is related to c++-pipes. It could also be dfs overload when reduce tasks close and validate all newly created dfs files. I see dfs client rpc timeout exception. But this alone does not explain the escalation in losing task trackers.
> I also noticed that the job tracker becomes rather unresponsive with rpc timeout and call queue overflow exceptions. Job Tracker is running with 60 handlers.

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