Back when I changed from supervisord to runit my life was substantially improved. That correctness means way fewer emergency maintenance ops issues in production.
First of all and mostly, we could never exactly figure it out what was going wrong.
This was a few years ago and I don't remember all the details. We just had occasional issues with stopping/starting and especially restarting processes when pushing a new version out or when a process crashed. I do remember it could occasionally report a successful restart and still leave the old process(es) running.
All my developers became very familiar with supervisord, and it was number 2 on the troubleshooting list (1. Did we introduce a bug in a recent commit? 2. Did supervisord do something weird again).
After we switched to runit, only devs that touched ops knew about it at all. And we all forgot it was there. That's what you want in an ops tool.
