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From "Devaraj K (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-6252) JobHistoryServer should not fail when encountering a missing directory
Date Wed, 11 Feb 2015 05:26:12 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-6252?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14315593#comment-14315593

Devaraj K commented on MAPREDUCE-6252:

Thanks [~cwelch] for the patch.

Would you mind adding a test for the same as part of the patch?

> JobHistoryServer should not fail when encountering a missing directory
> ----------------------------------------------------------------------
>                 Key: MAPREDUCE-6252
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-6252
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: jobhistoryserver
>    Affects Versions: 2.6.0
>            Reporter: Craig Welch
>            Assignee: Craig Welch
>         Attachments: MAPREDUCE-6252.0.patch
> The JobHistoryServer maintains a cache of job serial number parts to dfs paths which
it uses when seeking a job it no longer has in its memory cache, multiple directories for
a given serial number differentiated by time stamp.  At present the jobhistory server will
fail any time it attempts to find a job in a directory which no longer exists based on that
cache - even though the job may well exist in a different directory for the serial number.
 Typically this is not an issue, but the history cleanup process removes the directory from
dfs before removing it from the cache which leaves a window of time where a directory may
be missing from dfs which is present in the cache, resulting in failure.  For some dfs's it
appears that the top level directory may become unavailable some time before the full deletion
of the tree completes which extends what might otherwise be a brief period of failure to a
more extended period.  Further, this also places the service at the mercy of outside processes
which might remove those directories.  The proposal is simply to make the server resistant
to this state such that encountering this missing directory is not fatal and the process will
continue on to seek it elsewhere.

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