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From "Robert Joseph Evans (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-4226) ConcurrentModificationException in FileSystemCounterGroup
Date Mon, 07 May 2012 14:36:51 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-4226?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13269657#comment-13269657
] 

Robert Joseph Evans commented on MAPREDUCE-4226:
------------------------------------------------

The patch looks good to me too.  I see one small issue that was already in the code before
the patch, but I would like to see fixed. Write(DataOutputStream) is not synchronized.  I
assume that this is not a big deal because it can only be a problem if we are writing out
the counters at the same time we are adding in new counters.  I don't think that happens very
often, but if it does the number of schemes or the number of counters in a scheme could be
off.  This could result in exceptions on the reader side, or possibly some data corruption
in the counters on the reader side.

I also would like to see this fix go into branch-0.23 (The patch appears to apply cleanly
with no issues).

                
> ConcurrentModificationException in FileSystemCounterGroup
> ---------------------------------------------------------
>
>                 Key: MAPREDUCE-4226
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-4226
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: mrv2
>    Affects Versions: 0.23.1
>            Reporter: Tom White
>            Assignee: Tom White
>         Attachments: MAPREDUCE-4226.patch
>
>
> This was seen in a Hive job. I'll attach a failing test case.

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