I started using the JMX plugin of login, and I wondered how should I
shut it down when a web application is restarted. I haven't found a
function which unregisters the Configurator MBean. This object holds a
reference (through ContextAwareBase) to a Context. I am afraid that not
unregistering it causes a memory leak when a web application is restarted.

There should be a way to shutdown the JMX plugin. Or more generally an API to shut down the Logback system in its entirety: flush buffers, close files etc. It must be decided what to do if a log request arrives when or after logback is shutting down.