I am looking for something very close to an application server with these features: 

* it should handle a series of threads/daemons, allowing the user to start-stop-reload each one without affecting the others
* it should keep libraries separated between different threads/daemons
* it should allow to share some libraries

Currently we have some legacy code reinventing the wheel... and not a perflectly round-shaped one at that!
I thought to use Tomcat, but I don't need a web server, except maybe for the simple backoffice user interface (/manager/html).

Any suggestion? Is there a non-web application server, or is there a better alternative to Tomcat (more lightweight, for example, or easier to configure)? Thanks in advance.