I checked the execution and it looks like there is no problem with
transactions in JBossMQ.

I think the problem is with the default sweep interval value.

For usage scenario like what I described here I think this should be
very small in order to allow the sweep process to be fast enough and
to free unused space in database more often.

So now I'm experimenting with sweep interval of 200 instead of 20000.

With previous value it could take up to few minutes to run simple
query like this:

select * from jms_messages

I'm not sure why but usually this query triggers the sweep process and
as result it can return just a few records or none if message queue is
empty.

Doychin Bondzhev