Oracle bug? - Oracle opinion welcomed (copy of post in OC4J forum)

Question

Hi,
We are trying to run two web modules (A and B) on OC4J 10g standalone (on Windows 2000/XP), but we are facing a big problem.
After much investigation we really think it is a OC4J bug, but we are opened to any opinion or solution...
The problem is that a servlet or jsp on the web module B sometimes seems processed by OC4J by a thread created for the other web module A. As a consequence, if in the servlet (in fact in the method of a class instanciated in the servlet...) of B, we perform :
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
then we get the classloader of the web module A, and then we are not able to instantiate a class of B and get a "ClassNotFoundException".
This problem does not always happens. It is random even if it seems to have much more chance to happen if we execute requests on both modules in a little delay.
We tried running the two web module in a single EAR or in two separate EAR but it made no difference.
A debug of OC4J (with Eclipse 2.1) consolidates our mind it is a OC4J problem. Here is the kind of pile of execution we get for a thread HTTPRequestHandler of OC4J :
[top of pile]
ServletRequestDispatcher.forwardInternal(ServletRequest, HttpServletResponse) line 317
HttpRequestHandler.processRequest(ApplicationServerThread, EvermindHttpServlet, ...) line 790
=> in this method we have the attributes :
- thread.contextClassLoader = the one of web module A
- request.application.name = module_B_name and request.application.contextPatch = module_B_contextpath
ApplicationServerThread(Thread).run() line: 536
We already met classloader problems and resolved them putting some common librairies of A and B in the applib directory. But this can not be envisaged for our new problem. Moreover we want to keep a "parent first" classloading.
Has someone already met similar problems ?
Thanks for any help.

Answer 1

Thanks for the answers.
I use a OC4J 10g 9.0.4 version but an evaluation version so I have no support id for a TAR.
Sorry if my problem is difficult to understand (maybe it's my english which is difficult to understand!), but it is really difficult to explain...
In fact the OC4J output does not show the classloading problem.
I use Struts in the two WAR modules, and, for those who know Struts, it appears that I sometimes get a nullPointerException because in a Struts action my ActionForm is null (which should never happened). To find why the ActionForm is null I debug my application with Eclipse and I found the ActionForm was instanciated with the following code (classname is the name of a class extending the ActionForm class):
// Look up the class loader to be used
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
if (classLoader == null) {
classLoader = RequestUtils.class.getClassLoader();
// Attempt to load the specified class
return (classLoader.loadClass(className));
It appears that classLoader.loadClass(className) throws a ClassNotFoundException, and Struts, instead of throwing the exception, returns a value null for the ActionForm.
With the debug I watch which classloader was used and I was surprised to see it was the classloader of my other WAR module. Though the struts servlet is well called on the good web application, and all the struts class are in the web-inf/lib directory of each application.
I'm not sure this will make my problem easier to understand. Thanks for all who will make the effort of understand.
emmanuel