What Does The Message No Managed Connection Available mean?
It means that all possible connections to the db are in use and/or that a thread has timed-out waiting for a connection to open up.
Increase your connection pool size
to your -ds.xml file to increase
the number of connections available. The default is 20
There is an attribute
viewable on the jmx-console against the
that can help you understand how many connections you really need.
Tell your threads to wait longer for a connection to open up
to your -ds.xml file to increase the length of time to wait. The default is 30000 (5000 before JBoss-3.2.4) milli-seconds.
Make sure you are properly closing open connections