There are many programs that can do this.
On Ubuntu there is upstart (installed by
default)
Lots of people like http://supervisord.org/
monit as mentioned by @nathan
If you are looking for a python alternative there is a library that has just
been released called circus which
looks interesting.
And pretty much every linux distro probably has one of these built in.
The choice is really just down to which one you like better, but you would be
far better off using one of these than writing it yourself.
Hope that helps
