Stateful re-exec for Upstart Sessions? You bet!
As of Upstart 1.6 , restarting PID 1 is supported without losing state. So as soon as you get an update to either Upstart itself or one of its dependent libraries in Ubuntu, you'll be running the new version automatically, without the need for a reboot. But what about User Sessions ? Are they "second-class citizens"? Of course not! When PID 1 restarts, all the running Session Inits will automatically restart too . You won't notice this of course as your desktop session will continue to run and be fully functional but you too will be running the latest version of Upstart. How does this work? When an instance of Upstart has restarted, it signals this fact over D-Bus. From the user perspective, the upstart-event-bridge , listening to the system instance of Upstart running as PID 1, will generate a " :sys:restarted " event when it detects the restart. This in turn will cause the session job /usr/share/upstart/sessions/re-exec.conf to run. And that job re...