Hibernate version: 2.1.4
Name and version of the database you are using: Oracle 9.2.0.1

We are using the ThreadLocal pattern combined with the TransactionWrapper pattern for delegate method calls, so every call of a delegate method gets a new Hibernate session, starts a transaction, commits (or rollbacks) the transaction and then closes the Hibernate session.

The Problem:
On tests with a webstress tool, we got the effect, that with too many simultanious users the WebSphere AS seems to hang. On further examination we found out, if the count of users is higher than the max size of connections configured in WAS for the connection pool (e.g. 20 user, 15 connections), the problem occures. When we also raised the max number of connections, all went fine.
There is no lock on the database itself, the WAS only seems to be frozen.

We don't exactly know, if this could be a problem of WebSphere or of Hibernate, but it seems that as soon as a new session is requested for that no connection can be opened, the system freezes.

Maybe someone also had this issue and knows where the problem lies or where we can investigate further.

Any hint could be useful!

Thanks,
Steve

You have to do some more tracing to find the problem, impossible to debug by guessing. Remember that a Hibernate Session is lazy, that means it doesn't request a JDBC connection from the pool unless it needs one. However, it will keep the connection until you close() it.

Tracing is not easy because I don't know where exactly to look at.
I rerun the web stress test with 20 users and 10 connections in the pool. I also put in some output code to show, how many sessions are open (after the method ... returned).

After the 20th (!) session was opened, the precessing halted. I reduced the timeout of the connection pool to 3 minutes, after which this excption came:

[20.08.04 16:28:46:460 CEST] 5ee4b5ae SystemErr R requesting new session...
[20.08.04 16:28:46:460 CEST] 5ee4b5ae SystemErr R opened new Session ++++++++++++++++++++++++++++++++++++++++++++++++++++ 20


[20.08.04 16:31:39:475 CEST] 424af5b9 FreePool E J2CA0045E: Die Verbindung ist beim Aufruf der Methode queueRequest f

Hi,


did you solve that problem? We run into the same problem with Websphere 5.1, Hibernate 2.1.8 and Oracle 8.1.7.. Or do you have any advise?

Greetings

Dennis

Hi Dennis,

we did not find a solution for this. So we decided not to use the WebSphere connection pool and used a different one instead (Proxool). Now connection management is completely under our control. I know this can only be a workaround, but it works for us.

swb