iterator_benchmark.cr

require "benchmark"

RANGE = (1..10_000_000)
TIMES = 100_000

a1 = nil
a2 = nil
a3 = nil

Benchmark.bm do |x|
  x.report("regular") do
    # TIMES.times do
      a3 = RANGE.map { |x| x * 2 }.select { |x| 100 <= x <= 200 }.take(10)
    # end
  end
  x.report("manual") do
    TIMES.times do
      temp = [] of Int32
      count = 0
      RANGE.each do |x|
        x *= 2
        if 100 <= x <= 200
          temp << x
          count += 1
          break if count == 10
        end
      end
      a1 = temp
    end
  end
  x.report("iterator") do
    TIMES.times do
      a2 = RANGE.each.map { |x| x * 2 }.select { |x| 100 <= x <= 200 }.take(10).to_a
    end
  end
end

pp a1 == a2
pp a1 == a3
# pp a2 == a3

output.txt

               user     system      total        real
regular    0.070000   0.030000   0.100000 (  0.078614)
manual     0.020000   0.000000   0.020000 (  0.021547)
iterator   0.050000   0.000000   0.050000 (  0.054832)