[wp-hackers] APC-Nginx-Apache problems / memory problems on VPS

[Ian Douglas]

Many thanks to everyone who replied. The pointers given have been very useful.

At first we were getting RAM maxing out and crashing issues. Then we had difficulty getting online at all. 

Two things became clear:

1. CloudFlare was not playing well with Nginx and we had to disable it and even reset the DNS entries. We kept getting 502 Gateway Errors. However, this may have been due to the issue we encountered today.

2. Cpanel: chkservd scripts kept resetting the Apache port to 80. This basically kills Nginx, which ought to work on port 80.

We went to:  WHM -> Service Configuration -> Service Manager and unchecked HTTPD from the monitor column. Still it got reset.
We edited the  /etc/chkserv.d/chkservd.conf  and added "httpd:0"  Still it got reset.

We had to have HostGator admin chattr the chksrvd configuration file, forcing Apache to maintain it's port 8081 configuration.

Currently, we're recompiling. Next we will try to figure out what is going on that is taxing the CPU / RAM so much. 

I seriously don't think it's a plugin. I'm not really using anything that I haven't used on a shared environment. And although there are 51 plugins currently active, only about 8 add content to pages. A good deal of the others are benign, like Show ID for the backend or Favicon My Blog. The only plugin I imagine that may put stress on the server is Disqus. I have a couple of Twitter plugins, but would these crash a 768MB VPS? I also have three flash banners on the main page, each around 800k. Big deal, right?

Other stats: 9000 posts, 600 users, but only a handful active. Maybe 10 comments a day right now.

The base theme is WP-Prosper by Solostream. I love their themes. Very clean and precise. WP-Prosper was released 2010. It's WP3+ compatible.


QUESTION: 

I want to get the most efficient Wordpress install possible. Not just as a gimick, or to waste my own time, but for my end users, to ensure super fast access, and to get an install that allows our project serious growth in the period ahead.

Dion suggested that using Nginx makes W3TC redundant. Meanwhile, I read online various different views on the optimal use of applications / plugins like Nginx, APC, CloudFlare, Eaccelerator, W3TC, and Varnish.

Google CDN is also just around the corner.

What do people think is the optimal use of such applications / plugins?

At present I have Apache as a backend, and Nginx as a front end. I had to lose CloudFlare for now, but would like to look into Varnish, and possibly reimplementing CloudFlare (it has other features I think that are neat). Eaccelerator is also an option, via my VPS host.

Dion suggested that too many layers of caching could be a problem. I have not the technical knowledge of how these apps interact and differentiate to assess this.

What is the view of others?

I know some (perhaps many) will say, keep it simple, and I agree. But I'm asking about lightning fast, optimal installs. In particular with large scalability in mind, and run off a fairly modest VPS.

If anyone has suggestions for optimal use, please do share.

Thanks,
ian