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From "Owen O'Malley (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HADOOP-1524) Task Logs userlogs don't show up for a while
Date Sun, 01 Jul 2007 05:54:04 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-1524?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Owen O'Malley updated HADOOP-1524:
----------------------------------

    Status: Open  (was: Patch Available)

This doesn't work, because it doesn't preserve the offsets of the task logs as the older parts
are deleted. One of the requirements for the task logs is that you can read them as they are
generated. With this patch, the offsets will constantly be changing as old splits are deleted
and thus prevent users from tailing the log.

This bug clearly does need to be fixed however...

> Task Logs userlogs don't show up for a while 
> ---------------------------------------------
>
>                 Key: HADOOP-1524
>                 URL: https://issues.apache.org/jira/browse/HADOOP-1524
>             Project: Hadoop
>          Issue Type: Bug
>          Components: mapred
>    Affects Versions: 0.13.0
>            Reporter: Michael Bieniosek
>         Attachments: eliminate-split-idx.patch
>
>
> When I start a task and go to the task logs, nothing shows up for a while.  An examination
of TaskLog.Writer and TaskLog.Reader reveals:
> 1. The TaskLog.Reader relies on the presence of a split.idx to identify the parts of
the logs to display.
> 2. The TaskLog.Writer only updates the split.idx file when it moves on to the next log.
> As a result, updates to the log only get pushed when an entire file is done.
> Why is there a split.idx file?  It seems that since files are called part-00000, part-00001,
etc., the TaskLog.Reader can just look at all files and arrange them by alphabetical order.
 The split.idx file also contains file length, but this data is already stored by the filesystem.
> If nobody has objections, I'd like to write a patch to eliminate the split.idx file.

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