5 Rockin' Tips for Scaling PHP to 30,000 Concurrent Users Per Server

Jonathan Block, CTO at RockThePost.com, a crowdfunding company, has written a nice set of tips for smaller sites on how to scale a service on EC2 using a small two person development team. 

Their service has a typical small scale structure:

• PHP's Zend Framework 2
• Two m1.medium for web servers
• ELB to split the load
• master/slave MySQL database
• Siege for load testing

The very sensible tips that can handle 30,000 concurrent users per web server: 

• Use PHP's APC feature. APC is opcode cache that is "really a requirement in order for a website to have a chance at performing well."
• Put everything that's not a .php request on a CDN. Don't serve static files from your web server. They put everything on S3 and use CloudFront as their CDN. Recent CloudFront problems have caused them to serve directly from S3.
• Don't make connections to other servers in your PHP code. Making connections to other servers blocks the server and slows down processing. Use the APC key/value store for data storage and Varnish for caching full pages.
• Use Varnish. Using Varnish mage the single biggest difference to their performance under a load test. 
• Use a c1.xlarge. The c1.xlarge has 8 CPUs which really helps under load. The m1.medium has only 1 CPU for processing requests.

Pretty straightforward, yet good advice. The original article has many more details and is well worth reading.  

Comments

[jarrett]

Interesting. Goes to show how far behind we are. Our current application has around 6 c1.xlarge and 10 fm.medium servers. And it runs pretty slow with about a 100 users. Will read the full article.

[Warren]

But that is just the exterior site. Original article states that once users sign into the site into the 'interior' it only handles 1,000 per server? That's not very much..

[jon]

Jarrett,

Whats your site?

Jon

[Eric Caron]

I'm shocked to not see PHP-FPM mentioned in this post. Is it so de-facto now that everyone presumes its being used, or (more likely given APC is mentioned) was it overlooked entirely? The performance benefits of PHP-FPM, even within Apache, are astonishing and I'd literally expect a 2x performance boost for all PHP rendered files without any other changes being necessary.

[Roman]

This post about scaling site to 30,000, not about scaling PHP. PHP-FPM can process 350-400 max requests per second on one server

[reeze]

"Don't make connections to other servers in your PHP code.
Making connections to other servers blocks the server and slows down processing. Use the APC key/value store for data storage and Varnish for caching full pages."

Logic pages always need to connect to backend, eg, databases, memcache, or other backend services,
caching is a good ways to improve performance,

but how could you possible serve a page without a backend? many web application are far from been a simple page. hmmm I didn't get it. could anyone explain it?

[canhnm]

@reeze: it could be static page!