Comment 1 for bug 1480698

we see this in a lot of contexts downstream, and it turns out that based on load and such we do in fact need to raise the mysql_max_connections limit. Nova spawns a lot of Python processes, and each one can use anywhere from 1- 15 connections, 5 of which are persistently pooled.

I'm hearing on IRC that we're seeing it on Neutron as well and that the incidence of both seems to correspond. Basically, the source of the connections needs to be understood. I'd recommend using netstat to help figure it out, here's a line I used to identify individual processes:

    netstat -ntp | grep python | grep ESTABLISHED | grep 3306 | cut -c80-86 | sed 'sX/.*XX' | xargs -n1 ps -p | grep -v "CMD"