Ok, I have to admit that I'm getting a bit tired of all the Rails scaling questions. People seem to think that's Twitter's scaling problems are Rail's scaling problems. They aren't. Twitter's scaling problems do not equal Rails scaling problems or to put it more succinctly Twitter's scaling problems != Rails scaling problems. Rather than try and convince people that Rails can scale I'm just going to include a couple of stories about large companies that have scaled Rails to Billions of page views a month. Will this finally convince people that Rails scales?
Our first Rails app that scales is brought to us by AT&T. Yellowpages.com was rewritten from a Java app to a Rails app. It serves over 1.4 billion requests a month using 25 servers per data center. That's only 4 more servers than it was using while running under Java. The Java code base weighed in at 125k lines of code while the Rails code base came in at under 20k lines of code, including tests. The much larger Java code base didn't include any tests. The entire site was coded with at most five developers over a three month period. One thing that really stands out with Rails site is the maintainability. As a developer would you rather jump into and maintain a site with 125k lines of code or less than 20k lines of code? Over the life of the site AT&T might spend a couple extra grand on servers, but they will more than make it up by having less developers and getting new developers up to speed much quicker! And do you think there are more bugs and security issues hiding in 125k lines of code or in way less than 20k? If you want to look at more details you can check out this presentation from Rails Conf 2008.
Our next app is brought to us by LinkedIn. LinkedIn built a Facebook app called Bumpersticker that handles 1 billion page views monthly and around 100TB of data each month. This app is obviously also built on Ruby on Rails otherwise I wouldn't be including it here. ZDNet has a write up and there's also a video that looks to be from Joyent. This story isn't as interesting as the Yellowpages.com story because it wasn't a rewrite and it's harder to see the benefits of using Rails as compared to a traditional environment like ASP.Net or Java but I'm including it to point out that you can get the advantages of a great framework, cut development time and costs and still scale out to a billion page views a month.
So that's it. Can we please stop asking if Rails can scale and stop using these horribly outdated technologies like Java and .Net? Please? Pretty please?