[HIVE-13149] Remove some unnecessary HMS connections from HS2

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.0
• Fix Version/s: 2.3.0
• Component/s: HiveServer2
• Assignee: Aihua Xu
• Reporter: Aihua Xu
• Created: 24/Feb/16 19:49
• Updated: 27/Feb/24 22:24
• Resolved: 26/May/16 13:30

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.

  @Override
  public void run() {
    runner = Thread.currentThread();
    try {
      OperationLog.setCurrentOperationLog(operationLog);
      SessionState.start(ss);
      runSequential();

Issue Links

• breaks: HIVE-13499 TestJdbcWithMiniHS2 is hanging