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From "Kihwal Lee (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-4662) JobHistoryFilesManager thread pool never expands
Date Thu, 20 Sep 2012 19:49:07 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-4662?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13459892#comment-13459892
] 

Kihwal Lee commented on MAPREDUCE-4662:
---------------------------------------

In the second approach, we can also add {{executor.allowsCoreThreadTimeOut()}} to make core
threads expire after the keepalive time. I think this will be very close to the original design
intention.
                
> JobHistoryFilesManager thread pool never expands
> ------------------------------------------------
>
>                 Key: MAPREDUCE-4662
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-4662
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: jobhistoryserver
>    Affects Versions: 1.0.2
>            Reporter: Thomas Graves
>
> The job history file manager creates a threadpool with core size 1 thread, max pool size
3.   It never goes beyond 1 thread though because its using a LinkedBlockingQueue which doesn't
have a max size. 
>     void start() {
>       executor = new ThreadPoolExecutor(1, 3, 1,
>           TimeUnit.HOURS, new LinkedBlockingQueue<Runnable>());
>     }
> According to the ThreadPoolExecutor java doc page it only increases the number of threads
when the queue is full. Since the queue we are using has no max size it never fills up and
we never get more then 1 thread. 

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