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.

Possible solutions:

Increase your connection pool size

Add

<max-pool-size>whatever</max-pool-size>

to your -ds.xml file to increase

the number of connections available. The default is 20

There is an attribute

MaxConnectionsInUse

viewable on the jmx-console against the

ManagedConnectionPool

that can help you understand how many connections you really need.

Tell your threads to wait longer for a connection to open up

Add

<blocking-timeout-millis>whatever</blocking-timeout-millis>

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

CanJBossTellMeWhenIDontCloseAConnection?