public class ServletContextCleaner
extends Object
implements ServletContextListener

This class is capable of receiving notifications about the undeployment of a webapp, and responds by ensuring that commons-logging releases all memory associated with the undeployed webapp.

In general, the WeakHashtable support added in commons-logging release 1.1 ensures that logging classes do not hold references that prevent an undeployed webapp's memory from being garbage-collected even when multiple copies of commons-logging are deployed via multiple classloaders (a situation that earlier versions had problems with). However there are some rare cases where the WeakHashtable approach does not work; in these situations specifying this class as a listener for the web application will ensure that all references held by commons-logging are fully released.

To use this class, configure the webapp deployment descriptor to call this class on webapp undeploy; the contextDestroyed method will tell every accessible LogFactory class that the entry in its map for the current webapp's context classloader should be cleared.