Features > Logging a warning if you forget to start a Connection
A very common gotcha when working with JMS is forgetting to start the JMS connection, creating a consumer and not having it receive any messages. I myself have tripped up over this one many many times!
To try and help diagnose this mistake and give you an early warning by default ActiveMQ 4.2 detects this and generates a handy warning message telling you to call the Connection.start() method on the JMS connection.
For more details on this feature see the discussion of the warnAboutUnstartedConnectionTimeout property on the Connection Configuration URI