ServletContextListener.contextDestroyed() is called reliably at undeployment time.
But the destroy() methods of javax.servlet.Filters are never called.

The filter is not explicetely in the web.xml, it's automatically detected and initialized via init() at deployment, but destroy() is never called.

JavaMelody cannot shutdown it's timers because of this:
See last remarks in http://code.google.com/p/javamelody/issues/detail?id=360