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https://issues.apache.org/jira/browse/MAPREDUCE-4662?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13461601#comment-13461601
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Hemanth Yamijala commented on MAPREDUCE-4662:
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Hi, while the patch is certainly OK, I just wanted to understand how important
/ useful it is to save number of running threads (mainly from experience you
guys have on running production clusters).
Noting the timeout is set to a high value, i.e. 1 hour, we are essentially
saying the threads won't die until there are no jobs which have not completed
for an hour. I guess this can happen only when the cluster is completely idle
(i.e. no jobs being submitted) or there are very long running jobs (i.e. the
cluster is busy, but the history server isn't). In the former case, there
really is no strain on the resources. In the latter case, it will be useful.
However, is this a common scenario ?
> 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
> Assignee: Kihwal Lee
> Attachments: mapreduce-4662.branch-1.patch,
> mapreduce-4662.branch-1.patch
>
>
> 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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