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?
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.