Hello -

I have an application that uses a handful of Hibernate MBeans being deployed on JBoss. In JBoss 4.0.3, the Hibernate Service uses CGLIB as the default bytecode provider and my Hibernate MBeans behave fine.

In JBoss 4.0.4 and 4.0.5, however, the Hibernate Service uses javassist as the default bytecode provider. Unfortunately, javassist does not seem to be doing a smart enough job at classloading, and I suspect that it is filling up my PermGen space with unneccessary objects, ultimately resulting an OutOfMemory error. The only way to really be sure, though, would be to switch back to using CGLIB.

Unfortunately I can't find a straightforward way to do this. I've tried modifying the "persistence.properties" file, putting a hibernate.properties file in my classpath with the "hibernate.bytecode.provider" parameter set, adding a "-Dhibernate.bytecode.provider=cglib" flag to my JBoss startup script, even trying to set the environment option in code, but the Hibernate Service always reports on startup that it is using javassist as the bytecode provider.

There is some documentation that indicate that the bytcode provider for Hibernate 3.2 (deployed with JBoss 4.0.4 and 4.0.5) is pluggable, but this functionality does not seem to extend to the Hibernate Service.

I'm stumped - can anyone tell me how to do this?

Well, the solution was for me to rebuild the library containing the JBoss Hibernate MBean. In case this happens to anybody else, here's what to do. I did this for 4.0.5 GA; I imagine this would work for 4.0.4 as well.

1. Download the source.

2. Open up <jboss source>\hibernate-int\src\main\org\jboss\hibernate\jmx\Hibernate.java

3. Edit the createService() function so that it looks like this:



4. Save this revised class and do a build of JBoss - you'll find build scripts in <jboss source>\build\ for your platform, which in my case was XP, so I just ran the build.bat file.

5. When the build is complete, grab <jboss source>\hibernate-int\output\lib\jboss-hibernate.jar and replace the one in <your jboss distro>\server\default\lib with the one you just built.

This will switch all of your Hibernate services to use CGLIB as your bytecode provider. In my case, it cleared up all of the horrendous PermGen OutOfMemory problems I was having with javassist and my application is now happy again. Hopefully, future releases will support a pluggable bytecode provider for Hibernate MBeans.

I think it'd better find out why the -D option did not work.

Well, I imagine the "-D" option didn't work because the Hibernate Service has hardcoded javassist as its bytecode provider.