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https://issues.apache.org/jira/browse/HIVE-20737?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16655458#comment-16655458
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Sahil Takiar commented on HIVE-20737:
-------------------------------------

{quote} Opening of a Spark session and Job submission should be done as an 
atomic operation. {quote}

Well we intentionally don't do that. HoS by design de-couples opening a Spark 
session and submitting a job. There are a few reasons:
(1) In order to support static allocation in Spark, we have to open a session 
before we even have a job to submit (e.g. see {{SetSparkReducerParallelism}})
(2) At some point I think we should implement HIVE-17927; the reason is that 
opening a Spark session causes a Spark application to be created, which 
requires resource negotiation with YARN and the spawning of the Spark driver, 
which takes a non-trivial amount of time

{quote} Not to have case when we submit something having already closed session 
{quote}

We could just re-open the session if we try to submit a job on a closed session.

> Local SparkContext is shared between user sessions and should be closed only 
> when there is no active
> ----------------------------------------------------------------------------------------------------
>
>                 Key: HIVE-20737
>                 URL: https://issues.apache.org/jira/browse/HIVE-20737
>             Project: Hive
>          Issue Type: Bug
>          Components: Hive
>            Reporter: Denys Kuzmenko
>            Assignee: Denys Kuzmenko
>            Priority: Major
>         Attachments: HIVE-20737.1.patch, HIVE-20737.10.patch, 
> HIVE-20737.11.patch, HIVE-20737.12.patch, HIVE-20737.2.patch, 
> HIVE-20737.5.patch, HIVE-20737.6.patch, HIVE-20737.7.patch, 
> HIVE-20737.8.patch, HIVE-20737.9.patch
>
>
> 1. Local SparkContext is shared between user sessions and should be closed 
> only when there is no active. 
>  2. Possible race condition in SparkSession.open() in case when user queries 
> run in parallel within the same session.



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