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ScrollableResults closed by nested load

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Stefan Wachter

Post subject: ScrollableResults closed by nested load

Posted: Tue Sep 17, 2013 5:27 am

Newbie

Joined: Fri Feb 27, 2004 7:55 am
Posts: 17

Hi,

I have a HQL query that is executed by query.scroll() (see code below). The returned ScrollableResults can be iterated over without problems. Yet, when a session.load() operation is invoked in the loop then the next time scrollableResults.next() is called an exception is thrown that says that the result set is closed:

java.sql.SQLException: ResultSet not open. Operation 'next' not permitted. Verify that autocommit is off.

For the test a JTA user transaction and Derby was used. The problem occurs with Hibernate 4.2.5.Final.

Does anyone know a switch that prevents that the load operation causes the ScrollableResults to get closed? I already tried using a custom org.hibernate.context.internal.JTASessionContext where I overloaded the methods

Code:

 
   @Override
    protected ConnectionReleaseMode getConnectionReleaseMode() {
      return ConnectionReleaseMode.AFTER_TRANSACTION;
    }

    @Override
    protected boolean isAutoCloseEnabled() {
      return false;
    }

(BTW: When I use plain SQL to do the same, then no exception occurs).

TIA

--Stefan

Code:

    // Test-Code using HQL that throws an exception:
    Session session = sessionFactory.getCurrentSession();
    String attrKey = "attrAttr";
    String entityName = "e_d_test";
    session.save(entityName, newEntity(attrKey));
    session.save(entityName, newEntity(attrKey));
    session.flush();
    Query query = session.createQuery("from " + entityName);
    ScrollableResults scrollableResults = query.scroll();
    while (scrollableResults.next()) {
      Object o = scrollableResults.get();
      Map entityObject = (Map) ((Object[]) o)[0];
      Serializable instanceId = session.getIdentifier(entityObject);
      System.out.println("instanceId: " + instanceId);
      Object loaded = session.load(entityName, instanceId);
      System.out.println("loaded: " + loaded);
    }

Code:

    // Test-Code using plain SQL that does not throw an exception:
    DataSource ds = (DataSource)new InitialContext().lookup("java:comp/env/jdbc/myDbHost2.w1");
    Connection con = ds.getConnection("f5", null);
    con.createStatement().execute("insert into F5_E_D_TEST (ID, VERSION, A_ATTR) values (1, 1, 'x')");
    con.createStatement().execute("insert into F5_E_D_TEST (ID, VERSION, A_ATTR) values (2, 2, 'y')");
    ResultSet rs = con.createStatement().executeQuery("select * from F5_E_D_TEST");
    while (rs.next()) {
      long id = rs.getLong("ID");
      System.out.println("id: " + id);
      ResultSet rs2 = con.createStatement().executeQuery("select * from F5_E_D_TEST where id = " + id);
      while (rs2.next()) {
        String attr = rs2.getString("A_ATTR");
        System.out.println("attr: " + attr);
      }
    }

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Stefan Wachter

Post subject: Re: ScrollableResults closed by nested load

Posted: Tue Sep 17, 2013 6:52 am

Newbie

Joined: Fri Feb 27, 2004 7:55 am
Posts: 17

I debugged for a while and collected the following information: The result set is closed after the load operation has completed by the SessionImpl.afterOperation() method, because the transaction coordinater returns false when asked isTransactionInProgress():

Code:

   public void afterOperation(boolean success) {
      if ( ! transactionCoordinator.isTransactionInProgress() ) {
         transactionCoordinator.afterNonTransactionalQuery( success );
      }
   }

In that case TransactionCoordinater cleans up:

Code:

   public void afterNonTransactionalQuery(boolean success) {
      // check to see if the connection is in auto-commit mode (no connection means aggressive connection
      // release outside a JTA transaction context, so MUST be autocommit mode)
      boolean isAutocommit = getJdbcCoordinator().getLogicalConnection().isAutoCommit();
      getJdbcCoordinator().afterTransaction();

      if ( isAutocommit ) {
         for ( TransactionObserver observer : observers ) {
            observer.afterCompletion( success, this.getTransaction() );
         }
      }
   }

where JdbcCoordinater.afterTransaction() closes all Statements and ResultSets that were opened by during the current session. Apparently the problem is, that transactionCoordinator.isTransactionInProgress() returns false. The following code is executed:

Code:

   public boolean isTransactionInProgress() {
      return getTransaction().isActive() && getTransaction().getJoinStatus() == JoinStatus.JOINED;
   }

Here getTransaction().isActive() returns false. The instance org.hibernate.engine.transaction.internal.jta.JtaTransaction checks:

Code:

   public boolean isActive() throws HibernateException {
      if ( getLocalStatus() != LocalStatus.ACTIVE ) {
         return false;
      }

      final int status;
      try {
         status = userTransaction.getStatus();
      }
      catch ( SystemException se ) {
         throw new TransactionException( "Could not determine transaction status: ", se );
      }
      return JtaStatusHelper.isActive( status );
   }

Unfortunately, getLocalStatus() returns "NOT_ACTIVE" which causes the check to return false.

I wonder if the method JtaTransaction.isActive() has a bug because it checks its local status member. The local status member is set to "ACTIVE" only when the begin() method of the transaction instance is called explicitly. However, I thought that if JTA user transactions are used, then someone has not to care about Hibernate transactions. Begin/Commit/Rollback is signalled on the user transaction instance.

As a workaround I added the following lines of code to the HQL test:

Code:

    Session session = sessionFactory.getCurrentSession();
    session.beginTransaction();

This seems to work.

Could some initiate comment on this please?

TIA

--Stefan

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