upstream timed out

[Maxim Dounin]

Hello!

On Fri, Apr 13, 2012 at 04:59:55AM -0400, OlivierC wrote:

> Hi.
> 
> I'm the new admin of a website and its servers. I have a frontend nginx
> proxy server and an Apache backend.
> I sometimes have errors :
> 
> 2012/04/12 17:44:33 [error] 13442#0: *74193485 upstream timed out (110:
> Connection timed out) while reading response header from upstream,
> client: 98.87.76.65, server: www.mysite.tld, request: "POST /my/url
> HTTP/1.1", upstream: "http://12.23.34.45:80/my/url", host:
> "www.mysite.tld", referrer: "https://www.mysite.tld/another/url"
> 2012/04/12 17:44:33 [error] 13442#0: *74193485 no live upstreams while
> connecting to upstream, client: 98.87.76.65, server: www.mysite.tld,
> request: "POST /my/url HTTP/1.1", upstream: "http://backend/my/url",
> host: "www.mysite.tld", referrer: "https://www.goeland.fr/another/url"

[...]

> proxy_read_timeout              30;

[...]

> The problem seems to be recent and sometimes happens immediatly after
> clients have paid through the bank online credit card form which is
> integrated (we do not redirect to the bank website). It's a real problem
> for us since when it happens at that moment, clients think their order
> and paiement have not been saved and they order a second time (and also
> pay a second time).
> 
> I don't really know what i'm looking for : can it be a network
> connection problem between frontend and backend servers ? Is it because
> of the configuration of the proxy of the server ? or... ?

How long it takes for a backend server to generate response?  The 
30s read timeout might be just not enough.

Maxim Dounin