We recently upgraded from an older struts.jar to struts 1.3.8. Since then, when we try to deploy a new .war file dynamically in Tomcat, it fails because Tomcat is unable to delete just one file-- the struts-core-1.3.8.jar. That file remains "in-use" until the entire Tomcat webserver is restarted. It is as if a thread is started by Struts that does not exit nicely when interrupted. Or perhaps there is some kind of special class loader used by Struts that prevents the Tomcat webapp class loader from flushing some class from this jar.
I'm sorry if this problem is already known, but I could not find any issues that matched.