I checked the configuration in the postgresql.conf file and it had the default max_connections setting of 100
The notorious callback that drove me nuts — starring PostgreSQL, Unicorn, PubNub, EventMachine &…
Steve Robinson

I wonder what happens if we try to surpass this limit. Increase the 100 to a 200 maybe. Should we also increase the no. of Postgresql workers? What else ? (Not that I recommend it, but increasing capacity gives us time to debug)