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https://issues.apache.org/jira/browse/HIVE-17586?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16181921#comment-16181921
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Rui Li commented on HIVE-17586:
-------------------------------
[~xuefuz], the {{allowCoreThreadTimeOut}} controls whether we allow core
threads to time out like "excess threads":
{code}
* Sets the policy governing whether core threads may time out and
* terminate if no tasks arrive within the keep-alive time, being
* replaced if needed when new tasks arrive. When false, core
* threads are never terminated due to lack of incoming
* tasks. When true, the same keep-alive policy applying to
* non-core threads applies also to core threads.
{code}
So I think although the pool has a fixed size (core size == max size), the
threads can idle out. What do you think?
> Make HS2 BackgroundOperationPool not fixed
> ------------------------------------------
>
> Key: HIVE-17586
> URL: https://issues.apache.org/jira/browse/HIVE-17586
> Project: Hive
> Issue Type: Bug
> Components: HiveServer2
> Affects Versions: 1.1.0
> Reporter: Xuefu Zhang
> Assignee: Xuefu Zhang
> Attachments: HIVE-17586.1.patch, HIVE-17586.patch
>
>
> Currently the threadpool for background asynchronous operatons has a fixed
> size controled by {{hive.server2.async.exec.threads}}. However, the thread
> factory supplied for this threadpool is {{ThreadFactoryWithGarbageCleanup}}
> which creates ThreadWithGarbageCleanup. Since this is a fixed threadpool, the
> thread is actually never killed, defecting the purpose of garbage cleanup as
> noted in the thread class name. On the other hand, since these threads never
> go away, significant resources such as threadlocal variables (classloaders,
> hiveconfs, etc) are holding up even if there is no operation running. This
> can lead to escalated HS2 memory usage.
> Ideally, the threadpool should not be fixed, allowing thread to die out so
> resources can be reclaimed. The existing config
> {{hive.server2.async.exec.threads}} is treated as the max, and we can add a
> min for the threadpool {{hive.server2.async.exec.min.threads}}. Default value
> for this configure is -1, which keeps the existing behavior.
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