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https://issues.apache.org/jira/browse/HIVE-13149?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15176744#comment-15176744
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Szehon Ho commented on HIVE-13149:
----------------------------------

Hey Aihua the fix looks good.. I'm just wondering some questions..

1.  Do we really need another method 'Hive.setConf' that does the same thing as 
Hive.get?  I agree it's pretty confusing already, but now the class might be 
more confusing with two methods named differently that do the same thing?
2.  So now we dont initialize MSC any longer with SessionState.start, when does 
MSC get initialized now?

> Remove some unnecessary HMS connections from HS2 
> -------------------------------------------------
>
>                 Key: HIVE-13149
>                 URL: https://issues.apache.org/jira/browse/HIVE-13149
>             Project: Hive
>          Issue Type: Sub-task
>          Components: HiveServer2
>    Affects Versions: 2.0.0
>            Reporter: Aihua Xu
>            Assignee: Aihua Xu
>         Attachments: HIVE-13149.1.patch, HIVE-13149.2.patch
>
>
> In SessionState class, currently we will always try to get a HMS connection 
> in {{start(SessionState startSs, boolean isAsync, LogHelper console)}} 
> regardless of if the connection will be used later or not. 
> When SessionState is accessed by the tasks in TaskRunner.java, although most 
> of the tasks other than some like StatsTask, don't need to access HMS. 
> Currently a new HMS connection will be established for each Task thread. If 
> HiveServer2 is configured to run in parallel and the query involves many 
> tasks, then the connections are created but unused.
> {noformat}
>   @Override
>   public void run() {
>     runner = Thread.currentThread();
>     try {
>       OperationLog.setCurrentOperationLog(operationLog);
>       SessionState.start(ss);
>       runSequential();
> {noformat}



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