We are having ear re-deploment problems under Jboss and found that the thread groups created by quarts were not getting cleanup. (Don't ask me why, the groups hang in there even after a re-deployment). If the thread groups are made daemons they will get auto destroyed when the last thread exists. Here is the modified function from QuartzScheduler.java (this thing works and the groups are cleaned up)

public ThreadGroup getSchedulerThreadGroup() {
        if (threadGroup == null) {
            threadGroup = new ThreadGroup("QuartzScheduler:"
                    + getSchedulerName());
            threadGroup.setDaemon(true);
        }

return threadGroup;
    }