parallel_test.rb

require 'parallel'

# this does not work
parallel_sum = 0
parallel_res = Parallel.map((1..10), :in_processes => 2){|x| parallel_sum += x}
puts "parallel_sum = #{parallel_sum}"
puts "parallel_res = #{parallel_res.inspect}"

# this works as expected
sum = 0
res = (1..10).map{|x| sum += x}
puts "sum = #{sum}"
puts "res = #{res.inspect}"