[jira] [Created] (HIVE-24549) TxnManager should not be shared across queries

["John Sherman (Jira)" <ji...@apache.org>]

John Sherman created HIVE-24549:
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             Summary: TxnManager should not be shared across queries
                 Key: HIVE-24549
                 URL: https://issues.apache.org/jira/browse/HIVE-24549
             Project: Hive
          Issue Type: Bug
          Components: HiveServer2
    Affects Versions: 4.0.0
            Reporter: John Sherman
            Assignee: John Sherman


There are various sections of code that assume the DbTxnManager is not shared across concurrent queries in a session.
 Such as (which gets invoked during closeOperation):
 [https://github.com/apache/hive/blob/3f5e01cae5b65dde7edb3fbde8ebe70c1d02f6cf/ql/src/java/org/apache/hadoop/hive/ql/Driver.java#L868-L885]
{code:java}
   // is usually called after close() to commit or rollback a query and end the driver life cycle.
  // do not understand why it is needed and wonder if it could be combined with close.
  @Override
  public void destroy() {
    driverState.lock();
    try {
      // in the cancel case where the driver state is INTERRUPTED, destroy will be deferred to
      // the query process
      if (driverState.isDestroyed()) {
        return;
      } else {
        driverState.descroyed();
      }
    } finally {
      driverState.unlock();
    }
    driverTxnHandler.destroy();
  }
{code}
The problematic part is the: driverTxnHandler.destroy() which looks like:
{code:java}
 void destroy() {
   boolean isTxnOpen =
     driverContext != null &&
     driverContext.getTxnManager() != null &&
     driverContext.getTxnManager().isTxnOpen();
   release(!hiveLocks.isEmpty() || isTxnOpen);
 }
{code}
What happens is (rough sketch):
 Q1 - starts operation, acquires txn, does operation, closes txn/cleans up txn info, starts fetching data
 Q2 - starts operation, acquire txn
 Q1 - calls close operation which in turn calls destroy which sees the Q2s transaction information and cleans it up.
 Q2 - proceeds and fails in splitGeneration when it no longer can find its Valid*TxnIdList information.



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