Hi

We are using JBoss 4.2.3GA, EJB 3.0 (SessionBeans, EntityManager and 
EntityBeans) to an Oracle 10g.
We are having some issues with a concurrency scenario and the db connection 
pool. In a particular moment a persist or remove or merge or ejb query or 
native query locks a table or a row, and the other connection requests begings 
to been blocked, and therefore all connections in the pool are used and blocked 
until we getting java.sql.SQLException: Closed Connection for new requests.

We are not specifing any transaction isolation level, so we know that we are 
using Oracle's default READ COMMITTED, but for some reason we don't know, the 
locks are not been release and new requests are been blocked as well. We don't 
get any DEADLOCK exception, and we query the gv_$lock table to check the tables 
and queries, and every time is a different one. This happend no so often, but 
in a short time frame. If we kill the first lock in the database, the other 
ones are release. Some other times, we didn't need to kill the lock, it release 
the connection after several minutes and then the other requests execute 
normally, causing very ugly effects in our application.

The only thing that could be a clue on this, is maybe that something in our 
entity model relationship is making Oracle to lock the tables and rows. We have 
object with one-to-many, many-to-one and many-to-many relationships. But again, 
with READ COMMITTED should be an issue.

We though implementing the @Version annotation in the Entity model, but once 
again, it shouldn't be an issue because of the READ COMMITTED isolation level 
in the DB.

Any thought would be appreciate

Thanks a lot



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