502 bad gateway on thin server, why?

Question

I am making load test for app I am working on, on thin configuration behing nginx I get

connect() failed (111: Connection refused) while connecting to upstream

when I send much more request my configuration can handle. On puma I get only 504 timeout.

Why thin refuses connection on high load?

Answer 1

In your thin config there is a parameter called max_conns: <num connection> and when there are more connections incoming then specified thin refuses new connections.