no response nginx

[Maxim Dounin]

Hello!

On Thu, Apr 05, 2012 at 09:25:44AM +0900, shin fukuda wrote:

> Hi.
> 
> I have a problem with nginx-1.1.16 uses proxy_cache_lock on. 
> When high load or many request to nginx, Suddenly nginx seems hang, 
> no response at all. 
> In netstat "SYN_RECV","CLOSE_WAIT" too many. This problem needs 
> restarting nginx, and "CLOSE_WAIT" clear.
> 
> There is no problem in front-end nginx servers, but backends one.
> 
> Any clue?

I would suggest you are hitting some system limits.  Check nginx 
and system logs, as well as various system stats.  Check the state 
of nginx worker processes, most importantly wait channel (wchan, 
"ps -alx" should show one at least on FreeBSD and Linux).

Maxim Dounin