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From "Doug Cutting (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-3120) Large #of tasks failing at one time can effectively hang the jobtracker
Date Fri, 28 Mar 2008 19:06:25 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-3120?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12583147#action_12583147
] 

Doug Cutting commented on HADOOP-3120:
--------------------------------------

It sounds like we should experiment with AsyncAppender with a large buffer size (10k messages?)
and perhaps with blocking=false (drops messages when buffer is full, logging a count of dropped
messages).  Have you tried this, Pete?

> Large #of tasks failing at one time can effectively hang the jobtracker 
> ------------------------------------------------------------------------
>
>                 Key: HADOOP-3120
>                 URL: https://issues.apache.org/jira/browse/HADOOP-3120
>             Project: Hadoop Core
>          Issue Type: Bug
>         Environment: Linux/Hadoop-15.3
>            Reporter: Pete Wyckoff
>            Priority: Minor
>
> We think that JobTracker.removeMarkedTaks does so much logging when this happens (ie
logging thousands of failed taks per cycle) that nothing else can go on (since it's called
from a synchronized method) and thus by the next cycle, the next waves of jobs have failed
and we again have 10s of thousands of failures to log and on and on.
> At least, the above is what we observed - just a continual printing of those failures
and nothing else happening on and on. Of course the original jobs may have ultimately failed
but new jobs come in to perpetuate the problem.
> This has happened to us a number of times and since we commented out the log.info in
that method we haven't had any problems. Although thousands and thousands of task failures
are hopefully not that common.

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