Comparing time to compute SHA1 of integers using pure Ruby, Ruby threads, and Forking

sha1benchmark.rb

#!/usr/bin/env ruby
#
# To run this example, do first: `gem install parallel`
#
# Simple Benchmark on a 16-Core MacBook PRO:
#
# Number of CPU Cores: 16, total iterations: 10000
#
#              user     system      total        real
# ruby/01T  0.054921   0.000947   0.055868 (  0.055886)
# ruby/16T  0.059477   0.001923   0.061400 (  0.059579)
# ruby/16P  3.776095  16.852467 247.631315 ( 36.405558)

require 'digest'
require 'benchmark'
require 'parallel'
require 'fileutils'
require 'etc'

@num_cpus = Etc.nprocessors
@iterations = (ARGV[0] || 50000).to_i

puts "Number of CPU Cores: #{@num_cpus}, total iterations: #{@iterations}"

def sha1ruby(value)
  sprintf "%5d %s\n", value, Digest::SHA1.digest(value.to_s).bytes.map{ |b| b.to_s(16) }.join
end

def sha1proc(value)
  var = `/usr/local/bin/bash -c "printf #{value} | /usr/local/bin/sha1sum"`.chomp.split(/ /).first
  sprintf "%5d %s\n", value, var
end

Benchmark.bm do |bm|
  title = "ruby/01T"
  bm.report(title) do
    Parallel.map((0...@iterations).to_a, in_threads: 1) do |i|
      sha1ruby(i)
    end
  end

  title = "ruby/#{@num_cpus}T"
  bm.report(title) do
    Parallel.map((0...@iterations).to_a, in_threads: @num_cpus) do |i|
      sha1ruby(i)
    end
  end

  title = "ruby/#{@num_cpus}P"
  bm.report(title) do
    Parallel.map((0...@iterations).to_a, in_threads: @num_cpus) do |i|
      sha1proc(i)
    end
  end
end