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https://issues.apache.org/jira/browse/HIVE-16949?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16061317#comment-16061317
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Vihang Karajgaonkar commented on HIVE-16949:
--------------------------------------------
[~stakiar]
> Leak of threads from Get-Input-Paths thread pool when more than 1 used in
> query
> -------------------------------------------------------------------------------
>
> Key: HIVE-16949
> URL: https://issues.apache.org/jira/browse/HIVE-16949
> Project: Hive
> Issue Type: Bug
> Components: HiveServer2
> Reporter: Birger Brunswiek
>
> The commit
> [20210de|https://github.com/apache/hive/commit/20210dec94148c9b529132b1545df3dd7be083c3]
> which was part of HIVE-15546 [introduced a thread
> pool|https://github.com/apache/hive/blob/824b9c80b443dc4e2b9ad35214a23ac756e75234/ql/src/java/org/apache/hadoop/hive/ql/exec/Utilities.java#L3109]
> which is not shutdown upon completion of its threads. This leads to a leak
> of threads for each query which uses more than 1 partition. They are not
> removed automatically. When queries spanning multiple partitions are made the
> number of threads increases and is never reduced. On my machine hiveserver2
> starts to get slower and slower once 10k threads are reached.
> Thread pools only shutdown automatically in special circumstances (see
> [documentation section
> _Finalization_|https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ThreadPoolExecutor.html]).
> This is not currently the case for the Get-Input-Paths thread pool. I would
> add a _pool.shutdown()_ in a finally block just before returning the result
> to make sure the threads are really shutdown.
> My current workaround is to set {{hive.exec.input.listing.max.threads = 1}}.
> This prevents the the thread pool from being spawned
> [\[1\]|https://github.com/apache/hive/blob/824b9c80b443dc4e2b9ad35214a23ac756e75234/ql/src/java/org/apache/hadoop/hive/ql/exec/Utilities.java#L2118]
>
> [\[2\]|https://github.com/apache/hive/blob/824b9c80b443dc4e2b9ad35214a23ac756e75234/ql/src/java/org/apache/hadoop/hive/ql/exec/Utilities.java#L3107].
> The same issue probably also applies to the [Get-Input-Summary thread
> pool|https://github.com/apache/hive/blob/824b9c80b443dc4e2b9ad35214a23ac756e75234/ql/src/java/org/apache/hadoop/hive/ql/exec/Utilities.java#L2193].
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