[jboss-user] [Beginners Corner] - Managed Connection Pools

mastrivens do-not-reply at jboss.com
Thu Jul 13 19:12:22 EDT 2006

I am getting the 'NoManagedConnections' Exception this only happens after a while, but I confess I am confused by the JBoss documentation and the few examples of servlets working with JBoss don't seem to be much help.

I get a new connection object when I call the init method of each of my servlets (there are about 20), that is the only connection object I use for that servlet (I pass it as a parameter to the various factory classes I use within the servlet to do database access).

But if I understand correctly, there is only one instance of each servlet - so it shoud only be using one connection? So I should only be using the same number of connections as servlets?

Do I really need to close and create connections whenever I use JDBC?
Is there somewhere I can put a close command that wouldn't be too much rework? Or is there a timeout for spotting dead connections?

I already have a fairly large application and this would be painful to put it mildly... I thought that was the point of a managed connection pool? I have included the datasource XML file and also the code for getting a connection.

Thank-you in advance


I have project-ds.xml file to set-up a connection pool with Postgres:

  | <datasources>
  |   <local-tx-datasource>
  |     <jndi-name>MtrdbDS</jndi-name>
  |     <connection-url>jdbc:postgresql://myserver:5434/myDb</connection-url>
  |     <driver-class>org.postgresql.Driver</driver-class>
  |     <user-name>someUser</user-name>
  |     <password>somepassword</password>
  |       <metadata>
  |          <type-mapping>PostgreSQL 8.0</type-mapping>
  |       </metadata>
  |   </local-tx-datasource>

I use a JNDI call to get a connection from that pool:

  | 	public Connection getConnection() throws SQLException
  | 	{
  | 		Connection conn = null;
  | 		Context    ctx  = null;
  | 		DataSource ds   = null;
  | 		String sourceName = "";
  | 		try
  | 		{
  | 			ctx = new InitialContext();
  | 			if(ctx == null )
  | 				throw new NamingException("Error 'Db.getConnection' - No Context");
  | 			sourceName = this.getDbName(ctx);
  | 			ds = (DataSource)ctx.lookup(sourceName);
  | 		}
  | 		catch (NamingException e)
  | 		{
  | 			MtrErr.writeExc(MtrErr.OTHER_SOURCE,this.getClass().toString(),"getConnection",e);
  | 		}
  | 		catch (Exception e)
  | 		{
  | 			MtrErr.writeExc(MtrErr.OTHER_SOURCE,this.getClass().toString(),"getConnection",e);
  | 		}
  | 		if (ds != null) 
  | 		{
  | 			conn = ds.getConnection();
  | 		}
  | 		return(conn);
  | 	}

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