1个CPU上的Ruby机架应用程序 - 我应该运行多少个进程？

Question

I'm quite new to Ruby web apps (coming from java). I have VPS that has 1 CPU and 2GB of RAM and would like to play with some rails/sinatra stuff.

I'm using Ruby 2.1.0 MRI How does number of CPUs maps to number of web server's processes I need to run? I use puma as a web server and have default threads (0,16) set up. But I noticed there is also "workers" option that forks another process to better handle multiple requests.

Do I understand correctly that for such setup (1 CPU) there is no point in running 2 web server processes? The only reasonable setup is 1 process with threads?

Answer 1

Oh now this is a pretty big question!

The number of processes and threads aren't necessarily linked to the number of CPU's. It's more a case of the amount of memory available, the amount of concurrent requests and the amount of 'locking' stuff that's going on.

If you're going to have long running requests that block other requests, then having additional processes can help with that. You can still have more than one process with a single CPU.

There are a number of different servers in Ruby that handle scaling in different ways, Unicorn, Puma, Thin are some of them. Doing a search on Unicorn vs Puma vs Thin can turn up some useful blog posts on the topic.

Here's a couple

http://ylan.segal-family.com/blog/2012/08/20/better-performance-on-heroku-thins-vs-unicorn-vs-puma/ https://www.engineyard.com/articles/rails-server https://www.ruby-forum.com/topic/1822610

And some information on concurrency in Ruby http://merbist.com/2011/02/22/concurrency-in-ruby-explained/

The TL:DR answer is, it depends!