High load due to reload

[Maxim Dounin]

Hello!

On Tue, Jun 23, 2015 at 11:14:44AM +0200, 5hosting GmbH wrote:

> I have a small problem with a nginx system that acts as a loadbalancing
> proxy. We do have lots of vhosts and ssl certificates and each time we do a
> /etc/init.d/nginx reload, the load of our server goes up to 20 due to
> swapping.
> 
> Is there any other way to reload nginx to get aware of ssl or vhost changes
> without getting high loads?

When reloading a configuration, nginx reads a new configuration 
and starts new worker process, and then asks old worker processes 
to terminate gracefully.  See this link for a detailed 
description:

http://nginx.org/en/docs/control.html#reconfiguration 

This basically means that during configuration reload nginx memory 
consumption grows up for a while (and roughly doubles in some 
cases).  You should tune your system appropriately to make sure 
there are enough memory to start new worker processes without 
swapping.  In particular, if most of the memory is used for nginx 
buffers (proxy_buffers, proxy_buffer_size, and so on), tuning 
these buffers usually is enough.

-- 
Maxim Dounin
http://nginx.org/