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Date: Fri, 26 Feb 2016 14:37:18 +0000 (UTC)
From: "Aihua Xu (JIRA)" <jira@apache.org>
To: issues@hive.apache.org
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Subject: [jira] [Updated] (HIVE-13149) Remove some unnecessary HMS
 connections from HS2
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     [ https://issues.apache.org/jira/browse/HIVE-13149?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Aihua Xu updated HIVE-13149:
----------------------------
    Description: 
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}

  was:
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 of them like StatsTask, don't need to access HMS, currently a new HMS connection will be established for each 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}


> 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
>
>
> 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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