Sleep sort in ruby

sleep_sort.rb

#!/usr/bin/env ruby

# Outputs sorted args to stdout
# from:
#   http://dis.4chan.org/read/prog/1295544154/170
def sleep_sort(*args)
  args.each { |e| fork { sleep(e.to_f/1000); puts e } }
end
sleep_sort(*ARGV)

# Returns sorted array of args
def sleep_sort2(*args)
  [].tap { |a| args.map { |e| Thread.new{ sleep e.to_f/1000; a << e} }.each{|t| t.join} }
end

# usage: ruby sleep_sort.rb 1 3 51 22 372 2
puts sleep_sort2(*ARGV)

# monkeypatch array so you can do [3,12,4].sleep_sort
class Array
  def sleep_sort
    semaphore = Mutex.new
    [].tap do |a|                   # start with an empty array to hold sorted results
      self.map do |e|               # iterate over every element of this array instance
        Thread.new do               # create a Thread for each element
          sleep e.to_f/1000         # sleep longer for bigger numbers            
          semaphore.synchronize do  # wrap in Mutex to prevent race conditions
            a << e                  # wake up and add to the results array
          end
        end
      end.each do |t|               # iterate over every thread...
        t.join                      # ...and execute it
      end
    end
  end
end 

# for those who prefer a 1-liner
class Array
  def sleep_sort
    [].tap { |a| self.map { |e| Thread.new{ sleep e.to_f/1000; a << e} }.each{|t| t.join} }
  end
end

puts ARGV.sleep_sort

sleep_sort_benchmark.rb

require 'benchmark'

big_arr = []
50.times do   # use a small number to ensure results are sorted right
  big_arr << Random.rand(1000)
end

sorted = []
sleep_sorted = []

Benchmark.bm do |x|
  x.report { sorted = big_arr.dup.sort }         
  x.report { sleep_sorted = big_arr.dup.sleep_sort }
end

raise "sleep sort failed!" unless sorted == sleep_sorted
# results on ruby 1.9.2
# =>      user     system      total        real
#     0.000000   0.000000   0.000000 (  0.000026)
#     0.010000   0.010000   0.020000 (  0.997363)

Wow! You took it to the next level. I'll come back and try this out when I find some time. Thanks!

Updated the gist with a monkeypatch to Array based on c2h2's comment.

just one little tip, u dont actually need require 'thread' for nowadays ruby

Thanks, I ran a quick test and you are right. I updated the gist accordingly.