Understanding Websphere Internals

Question

I have the misfortune of having to help troubleshoot some performance issues in an ancient application running on Websphere 6.0.2. It runs on an SLES9 using the IBM JDK 1.4.2. There is not a single part of this application that could be considered well behaved however that's not what my Q is about.

My Q is whether there are any good links that explain what some of the WAS internals are, for instance what does the NotificationServiceDispatcher thread do? How does it relate to LocalNotificationServiceDispatcher? What notifications is it dispatching anyway? How does WAS manage WebContainer threads (in what circumstances do they die? what consumes them?)?

There are inevitably lots more Qs that could result from this so I was really looking for links that discuss the above rather than specific answers. I have looked on the IBM site but I find it competes with oracle for "useless search, impossible to navigate".

Answer 1

IBM's redbooks are usually decent. Here's the one for WAS 6. I don't know if it answers your specific questions or not, but it sounds like its more than you've got now. Good luck.

Answer 2

I know you didn't ask for specific answers, but in case someone finds this question and is looking for specific answers...

The NotificationServiceDispatcher thread pool is used for sending notifications to out-of-process JMX listeners, and the LocalNotificationServiceDispatcher does likewise for in-process JMX listeners.

WebContainer threads are managed using a ThreadPool. The Thread pool settings InfoCenter topic provides a brief introduction to some of the settings used to manage the threads. In summary, threads will die when the pool has more than the minimum number and the thread has not done any work for a specified interval.