A barrage of unexplained timeouts
normalperson at yhbt.net
Tue Aug 20 17:40:18 UTC 2013
nick at auger.net wrote:
> "Eric Wong" <normalperson at yhbt.net> said:
> > Can you take a look at the nginx error and access logs? From what
> > you're saying, there's a chance a request never even got to the Rails
> > layer. However, nginx should be logging failed/long-running requests to
> > unicorn.
> The nginx access logs show frequent 499 responses. The error logs are filled with:
> connect() failed (110: Connection timed out) while connecting to upstream
> upstream timed out (110: Connection timed out) while reading response header from upstream
> What specific pieces of information should I be looking for in the logs?
Do you have any other requests in your logs which could be taking
a long time and hogging workers, but not high enough to trigger the
unicorn kill timeout.
(enable $request_time in nginx access logs if you haven't already)
Is this with Unix or TCP sockets? If it's over a LAN, maybe there's
still a bad switch/port/cable somewhere (that happens often to me).
With Unix sockets, I don't recall encountering recent problems under
Linux. Which OS are you running?
I hit several TCP bugs in the early 3.7 Linux kernels, too...
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