Weblogic Optional Packages - Permgen Memory Space

Question

Hi,
We are packaging some common jars as Optional Packages in weblogic and using them from different EAR files.We know for classes in side the EAR, each classloader creates individual clazz objects in the permgen space.
For classes inside the Optional packages and which are referenced in multiple EAR,does weblogic create seperate clazz instances in the permgen space for each classloader? If so then it would mean that classes inside the Optional Package will be created multiple times in the permgen space (attributed to different classloaders)
Any idea on the behaviour will be highly appreciated.Is the situation same with shared libraries ?

Answer 1

Depends on where your optinal classes are located.
If you insert them in the system (or server) classloader they will be loaded once, by the system
classloader. You can use the ${DOMAIN_HOME}/lib directory for this purpose. The jars located in
this directory will be picked up and added to the end of the server classpath at server startup.
The jars will be ordered lexically in the classpath.
If you are using shared libraries, these shared libraries will be merged at runtime with the
applications referencing them, so they will be local to the application and to my knowledge
loaded by the classloader of the application and not a separate shared library classloader. Thus
if you reference the shared library from multiple applications, the shared libraries get merged
multiple times and loaded multiple times. The reason is that WebLogic uses classloading
isolation between the deployed applications, so that from a classloading perspective
other applications do not bother other applications.