Nginx + Circus + chaussette

Hello

I am using Nginx with Circus. Circus is used with chaussette

Very rarely I am seeing 504 error

Nginx error log says

upstream timed out (110: Connection timed out) while reading response
header
from upstream, client: A.B.C.D, server: servername.com, request: “GET /
HTTP/1.1”, upstream: “http://127.0.0.1:8080/”, host: “servername.com

The process listening on port 8080 are circusd and chaussettes. What
could
be the cause

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