nginx on high load (upstream prematurely closed connection while reading response header from upstream)

[Francis Daly]

On Wed, May 18, 2016 at 04:50:24AM -0400, muzi wrote:

Hi there,

> I am facing strange issue, during load test and peak load of more than 3k
> concurrent users, get below errors in nginx logs continuously.
> 
> 2016/05/18 11:23:28 [error] 15510#0: *6853 upstream prematurely closed
> connection while reading response header from upstream, client: x.x.x.x,
> server:abc.com, request: "GET / HTTP/1.1", upstream:
> "fastcgi://127.0.0.1:9000", host: "10.50.x.x"

"upstream" here is your fastcgi server. The nginx message is that the
fastcgi server broke the connection.

> And beside of above error frequently, below error come gradually
> 
> 2016/05/18 11:23:28 [error] 15510#0: *7431 recv() failed (104: Connection
> reset by peer) while reading response header from upstream, client: x.x.x.x,
> server: abc.com, request: "POST / HTTP/1.1", upstream:
> "fastcgi://127.0.0.1:9000", host: "10.50.x.x", referrer: "http://10.50.x.x"

And that message is that the fasctcgi server broke the connection.

It is probably worth investigating what the fastcgi server thinks is
happening -- perhaps it is not configured to handle the load it is
being given?

	f
-- 
Francis Daly        francis at daoine.org