I did something similar some time ago, but in far simpler form. I called it "process race" - prace for short.

Basically you write simple shell script to start your processes and at the and you exec prace so it takes over children of shell:

  #!/bin/sh
  proc1 &
  proc2 &
  proc3 &
  exec prace

You could also do this as a part of shell script in this way:

  (proc1 & proc2 & proc3 & exec prace)

Then prace has simple job. It wait(2)s and then kills all children.

I have it somewhere if someone is interested, but I can access it in few hours. But everything is written in at most 2/3 terminal screens worth of C.