[jira] [Commented] (HIVE-16949) Leak of threads from Get-Input-Paths and Get-Input-Summary thread pool

["Vihang Karajgaonkar (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-16949?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16143182#comment-16143182 ] 

Vihang Karajgaonkar commented on HIVE-16949:
--------------------------------------------

+1 LGTM.

> Leak of threads from Get-Input-Paths and Get-Input-Summary thread pool
> ----------------------------------------------------------------------
>
>                 Key: HIVE-16949
>                 URL: https://issues.apache.org/jira/browse/HIVE-16949
>             Project: Hive
>          Issue Type: Bug
>          Components: HiveServer2
>            Reporter: Birger Brunswiek
>            Assignee: Sahil Takiar
>         Attachments: HIVE-16949.1.patch
>
>
> 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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