RubyInline, Ruby and C/C++ Happy Together

Posted by ben, Fri Mar 09 10:11:00 UTC 2007

If you are like me and somewhat offended by joel’s post a while back on ruby performance then RubyInline is for you. He also has another product called ruby2c but I haven’t tried it yet.

Basically, RubyInline lets you put other code inside of a ruby class and it will be compiled and called dynamically from the ruby code. Right now it only supports c and c++.

Here is a trivial example of a class that has 2 methods one in ruby and one in c. They both loop from 1 to 1,000,000 each time calling “i * i” and saving it in a variable x:

require 'rubygems'
require 'inline'
require 'benchmark'

class FastClass
  def ruby_loop
    1.upto 1000000 do |i|
      x = i * i
    end
  end

  inline(:C) do |builder|
    builder.add_compile_flags '-x c++', '-lstdc++' 
    builder.c ' 
      void c_loop() {
        int i = 1;
        while (i++ <= 1000000) { 
          long x = i * i;
        }
      }' 
  end
end

fc = FastClass.new

Benchmark.bm(10) do |b|
  b.report('ruby') { fc.ruby_loop }
  b.report('c') { fc.c_loop }
end

you can see from the benchmark stats that c is WAY faster:

                user     system      total        real
ruby        4.790000   0.130000   4.920000 (  5.950551)
c           0.010000   0.000000   0.010000 (  0.001360)

Feel free to use this technique on a highly computational portion of code that appears to be a bottle neck.

Filed Under: | Tags: c performance ruby