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https://issues.apache.org/jira/browse/LIVY-1003?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17856650#comment-17856650
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wangdengshan commented on LIVY-1003:
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[https://github.com/apache/incubator-livy/pull/449]
> Interactive session - Setting large value of rsc.server.connect.timeout
> blocks other tasks
> -------------------------------------------------------------------------------------------
>
> Key: LIVY-1003
> URL: https://issues.apache.org/jira/browse/LIVY-1003
> Project: Livy
> Issue Type: Bug
> Components: RSC
> Affects Versions: 0.8.0
> Reporter: Tom Chamnongvongse
> Priority: Minor
>
> Problem:
> Livy is configured to deploy interactive sessions on YARN with
> `livy.rsc.server.connect.timeout` configured to a high value. Timeout is
> increased to allow more time for Livy session to be in YARN `ACCEPTED` state
> to prevent Livy server from killing the YARN app within the default timeout
> of 90 seconds.
> Until the app is in YARN `RUNNING` state, it takes up a thread in Scala's
> global execution context - I think due to
> https://github.com/apache/incubator-livy/blob/v0.8.0-incubating/server/src/main/scala/org/apache/livy/server/interactive/InteractiveSession.scala#L474.
> Creating too many of these sessions that are stuck in `ACCEPTED` state
> causes other tasks that use that global execution context to be queued up.
> How to reproduce:
> 1. Set `livy.rsc.server.connect.timeout` to something high like 24h.
> 2. Create enough interactive livy sessions in YARN so that they are queued in
> ACCEPTED state. The number of sessions that are stuck in ACCEPTED state
> should be equal to global execution context [thread pool
> size|https://docs.scala-lang.org/overviews/core/futures.html#the-global-execution-context]
> (Runtime.availableProcessors)
> 3. Try to delete a session using DELETE /sessions/{sessionId} and it should
> hang until one of the sessions is no longer stuck in ACCEPTED state.
>
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