iteration_overhead.rb

require 'benchmark'

NA = 1000000
N  = 1000

ARR = Array.new(NA) { rand }.freeze


Benchmark.bm do |x|

  x.report("one iteration") do
    N.times do
      acc = 0
      ARR.each do |e|
        acc += e >= 0.3 ? e + 2 : 0
      end
    end
  end

  x.report("many iterations") do
    N.times do
      acc = ARR.select {|e| e >= 0.3 }
               .map {|e| e + 2 }
               .reduce(0, :+)
    end
  end

end


##
##                  user         system   total      real
## one iteration    87.610000    0.000000 87.610000  ( 87.631403)
## many iterations  138.400000   0.030000 138.430000 (138.454974)
##