title: JBoss JDBC warning - "Unable to fill pool"
body: <p>We're getting this random warning from JBoss..  any idea why?</p>
  
  <p>It happens at random times when there are no active threads.  Everything works when any processing resumes.</p>
  
  <pre><code>13:49:31,764 WARN  [JBossManagedConnectionPool] [ ] Unable to fill pool
  org.jboss.resource.JBossResourceException: Could not create connection; - nested throwable: (java.sql.SQLException: Listener ref
  used the connection with the following error:
  ORA-12516, TNS:listener could not find available handler with matching protocol stack
  The Connection descriptor used by the client was:
  //localhost:1521/orcl
  )
          at org.jboss.resource.adapter.jdbc.xa.XAManagedConnectionFactory.createManagedConnection(XAManagedConnectionFactory.java
  :144)
          at org.jboss.resource.connectionmanager.InternalManagedConnectionPool.createConnectionEventListener(InternalManagedConne
  ctionPool.java:577)
          at org.jboss.resource.connectionmanager.InternalManagedConnectionPool.fillToMin(InternalManagedConnectionPool.java:524)
          at org.jboss.resource.connectionmanager.PoolFiller.run(PoolFiller.java:74)
          at java.lang.Thread.run(Thread.java:619)
  Caused by: java.sql.SQLException: Listener refused the connection with the following error:
  ORA-12516, TNS:listener could not find available handler with matching protocol stack
  The Connection descriptor used by the client was:
  //localhost:1521/orcl
  </code></pre>
  
  <hr>
  
  <p><strong>Update</strong>: As per richj's post, here is the format of one of the four data sources we are using:</p>
  
  <pre><code>  &lt;xa-datasource&gt;
          &lt;jndi-name&gt;ABCOracleDS&lt;/jndi-name&gt;
          &lt;track-connection-by-tx/&gt;
          &lt;isSameRM-override-value&gt;false&lt;/isSameRM-override-value&gt;
          &lt;xa-datasource-class&gt;oracle.jdbc.xa.client.OracleXADataSource&lt;/xa-datasource-class&gt;
          &lt;xa-datasource-property name="URL"&gt;jdbc:oracle:thin:@//localhost:1521/orcl&lt;/xa-datasource-property&gt;
          &lt;xa-datasource-property name="User"&gt;myuser&lt;/xa-datasource-property&gt;
          &lt;xa-datasource-property name="Password"&gt;mypw&lt;/xa-datasource-property&gt;
          &lt;min-pool-size&gt;20&lt;/min-pool-size&gt;
          &lt;max-pool-size&gt;200&lt;/max-pool-size&gt;
          &lt;valid-connection-checker-class-name&gt;org.jboss.resource.adapter.jdbc.vendor.OracleValidConnectionChecker
          &lt;/valid-connection-checker-class-name&gt;
          &lt;exception-sorter-class-name&gt;org.jboss.resource.adapter.jdbc.vendor.OracleExceptionSorter
          &lt;/exception-sorter-class-name&gt;
          &lt;no-tx-separate-pools/&gt;
  
          &lt;metadata&gt;
              &lt;type-mapping&gt;Oracle10g&lt;/type-mapping&gt;
          &lt;/metadata&gt;
      &lt;/xa-datasource&gt; 
  </code></pre>