How many connections can nginx handle?

Maxim Konovalov maxim at
Fri Nov 9 09:47:10 UTC 2012

On 11/9/12 7:46 AM, arnoldguo wrote:
> I have a server running proxy_pass the http request(mainly GET,html,jpg
> etc.) to backend server(20+ server running nginx cache).
> this server with 32 core CPU,64G RAM,2X 10G NIC,RHEL 6.3,backend server with
> 1000M NIC.
> When the load raise to 300k connections,3Gbps network traffic,new connection
> can not be serviced,cannot connect to nginx's port,but the system load is
> low(~1.00),and has many free memory,
> no errorlog in /var/log/message,has some nginx errorlog like"upstream timed
> out to backend server",
> but the backend's service is normal,load is not hight...
> i have tune  tcp config,can handle 2000K conn,it seems that nginx cannot
> handle so much connection?
How did you do that and how did you check that the OS can handle 2M
tcp connections?

> nginx config:
> worker_processes 32;use worker_cpu_affinity;
> keepalive 32 to backend servers,
> proxy_buffering on or off has the same result...
It's almost always about tuning various OS limits not nginx.

As for nginx, this link is a good start:

Maxim Konovalov
+7 (910) 4293178

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