supervisor：How is this different from daemontools ?

"daemontools has too much focus on security as opposed to being a process manager for my taste." Hopefully someone will know more.

The means of process management is exactly like daemontools. It just wraps it up a bit differently. It gives you a more interactive way of managing the processes (supervisorctl), and provides a couple different kinds of APIs to manage the processes. It also handles multiple processes at once (which I guess launchd also does, but daemontools doesn't). It has some other features as well. You can also do things like give non-root users access to restart processes, and there's a web interface to see the status of processes, and supervisor can manage and rotate output, and other stuff.

If you like the model of daemontools, but don't like the interface so much, then supervisor would be good to look at. If you like daemontools, but want to extend the process management programmatically, then supervisor might also be good to look at.