Parallel map: Originally from http://project.ioni.st/post/2332#snippet_2332

array_pmap.rb

# Parallel map
# Originally from http://project.ioni.st/post/2332#snippet_2332
class Array
  def pmap
    threads = []
    0.upto(size - 1) do |n|
      threads << Thread.new do
        yield(at(n))
      end
    end
    threads.collect {|thread| thread.value}
  end
end

# Trade-off between resource consumption
# and speed of execution.
# Much faster in some scenarios, 
# much slower in others.

# e.g.
def expensive_operation
  open('http://google.com').read
end
# Expensive operation 50 times
#          user     system   total    real
# map  50x  0.3400   0.2100   0.5500 ( 17.334429)
# pmap 50x  0.3000   0.2500   0.5500 (  1.200705)