All:
I am working on a reporting application that maintains an open Hibernate Session across multiple HTTP requests.
The session cache appears to be unbounded in size: if enough data is requested from the database, then I get an OOM error in my application and it's because the Session cache is never purged of older data (AFAICS).
Is this expected behavior? I want to go into this application and reimplement with shorter Hibernate Sessions (probably one per request) and a second level cache. I believe that will be a much superior approach. But even then I'm concerned that enough data can be requested as a result of a single HTTP request that the session cache could trigger an OOM (this is a data mining application).
So I need a short term solution to my OOM problem with the session level cache. Is there any workaround or reconfiguration to the Hibernate Session Cache that I can make?

Thanks in advance,
Frank Kurzawa


Hibernate version:3

Mapping documents:

Code between sessionFactory.openSession() and session.close():
Lots and lots of data is retrieved from the database.


Full stack trace of any exception that occurs:

Name and version of the database you are using:
Oracle 9i


The generated SQL (show_sql=true):

Debug level Hibernate log excerpt:

You can configure the ehcache or one of the other to suite your needs. You can also configure the life time of cached instances. Read about ehcache on their website or in the wiki.

I do not know the size of your base data, but it will be hard to hold a lot of data in the cache. You may consider to use Hibernate on database views.

Regards Sebastian

Hi Sebastion,
We will be running a second level cache soon. But we are having a problem with the Session (first level) cache, which does not seem to be bounded or have any mechanism for removing data. It just seems to grow as big as the data that is requested.
Is this behavior modifiable? Aside from calling session.evict() on individual objects?

Thanks,

Frank

You are missusing the session. It is not intended as long running object and as far as I know there is nothing like the functions you are looking for in the session.

You must go for a second level cache. The configuration is very simply and should take you much time.

Regards Sebastian

In V3 Why not use SessionFactory.evict(class) to clear 2nd level out?

Thanks, LaLiLuna.
I agree the session level cache is being unused. It was my predecessor but that is cold comfort when we are already on a tight deadline.
We will be seeing about getting the 2nd level cache in there as soon as possible.

Regards,

Frank