Cannot create InitialDirContext sometimes

Question

We have implemented our own DirContext pool which implements the InitialContextFactory interface. The InitialContextFactory has a reference to a singleton class managing the pool.
Sometimes we cannot create a new InitialDirContext with the following error message: "Cannot instantiate class" refering to the InitialContextFactory class. The Root exception is java.lang.ClassNotFoundException. So it seems that the InitialContextFactory class is lost sometimes. Using the -Xnoclassgc improves the situation somewhat. It does still happen sometimes, but now it can start working again without restarting the application. This does not happen all the time, only sometimes, so it does not seem to be a simple case of an erronous classpath.
Our application creates new Contexts often so "new InitialDirContext" and the DirContext close method is called often.
Anyone recognizing the problem or have any suggestions on how to further investigate the cause of the problem? We have monitored memory and file descriptor usage (we are running on a Solaris 10 environment) and we are experiencing leakage due to other components in the system, but it seems that the described problem happens before memory and file descriptors starts to leak.
Best regards,
Andreas

Answer 1

We found the solution to the problem, maybe it can help somebody else:
We had a C-module that used an Event-mechanism in Java. Sometimes when an event was fired, our threadpool created a new thread. If the event originated from the C-module in this case, the created thread inherited the ContextClassLoader from the C-thread, which was null.
Since JNDI uses the threads ContextClassLoader when loading factory classes, our factory was not found.
Best regards,
Andreas