I have been playing with the Thin + nginx combo for a while now. I did a lot of stress testing using an actual application that is ready to go for production soon. I played with both Thin and Mongrel to see if there is a big difference.
I need not mention that I didn’t bother testing Apache as a proxy balancer instead of nginx, I am getting an earth shaking 7900 req/s for static requests using nginx on an application serving unit.
Our application serving units are xen virtual servers with a quad core processor each. It runs The nginx web server and the web application cluster (Mongrel currently, but may be Thin too). The cluster runs 10 Mongrels and 4 nginx workers. Any application can scale its front end by adding more of those application serving units.
While testing I was surprised that after a certain test Thin was giving me results that were slower than Mongrel. Repeating the tests or letting the system load cool down didn’t help. What I found was that I hit the memory limit and the system started swapping. I shut down one Thin server and suddenly they started to outperform (albeit by a small margin) the Mongrel cluster again.
I tested against three of the very heavy pages. The results were the average of three runs for each page in the specified concurrency/connections pair
So here are the numbers (using Apache Bench):
(Concurrency/Connections)
100/1000 200/1000 200/10000
Thin 104.3req/s 115.7req/s 123.1req/s
Mongrel 100.6req/s 113.2req/s 121.6req/s
The figures speak for themselves; while Thin is constantly faster than Mongrel, the difference is negligible. I am assuming that this is due to the fact that most of the time is spent in processing the Rails stack and doing IO with memcached then sending the actual repsonse back. The raw differences between Thin and Mongrel are dwarfed by the time spent in Rails. You will see a good advantage for Thin when you are doing very small requests that do little processing and send small responses. While this is not the case for this particular test, it is typical in many Ajax intensive applications. And since this application is full of Ajax requests, I believe that we might opt for Thin at the end.
I have to say that I was very happy with the results so far. Mongrel and Thin are both robust and nginx is a true gem ;). The application is expected to generate lots of traffic and I am confident that scaling would only be a matter of adding more boxes. My next challenge is to get more performance out of those boxes. Which is a possibility since Evan is working on a much better memcached client for Ruby. Knowing that Evan is working on Mongrel too is reassuring me regarding its future.
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