[HIVE-1760] Mismatched open/commit transaction calls in case of connection retry

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.7.0
• Fix Version/s: 0.7.0
• Component/s: Metastore
• Hadoop Flags: Reviewed
• Assignee: Paul Yang
• Reporter: Paul Yang
• Created: 29/Oct/10 22:55
• Updated: 21/Nov/13 03:30
• Resolved: 30/Oct/10 04:59

Description

Consider the create table function (parts removed for simplicity):

    private void create_table_core(final RawStore ms, final Table tbl)
        throws AlreadyExistsException, MetaException, InvalidObjectException {

      Path tblPath = null;
      boolean success = false, madeDir = false;
      try {
        ms.openTransaction();

        // get_table checks whether database exists, it should be moved here
        if (is_table_exists(tbl.getDbName(), tbl.getTableName())) {
          throw new AlreadyExistsException("Table " + tbl.getTableName()
              + " already exists");
        }

        ms.createTable(tbl);
        success = ms.commitTransaction();

      } finally {
        if (!success) {
          ms.rollbackTransaction();
          if (madeDir) {
            wh.deleteDir(tblPath, true);
          }
        }
      }
    }

A potential openTransaction() / commitTransaction() mismatch can occur if the is_table_exits() method call experiences a connection failure.

Since get_table() in is_table_exists() uses executeWithRetry(), the transaction will be rolled back and get_table() will be called again if the is a connection problem. However, this rollback and retry will reset the global openTransactionCalls counter back to 0, effectively canceling out the openTransaction() call.

Then later in the method when commitTransaction() is called, Hive will throw an error similar to the following:

Caused by: java.lang.RuntimeException: commitTransaction was called but openTransactionCalls = 0. This probably indicates that there are unbalanced calls to openTransaction/commitTransaction

A similar problem exists with create_type_core()

Issue Links

• relates to: HIVE-4996 unbalanced calls to openTransaction/commitTransaction