Benchmark enumerator patterns

benchmark_lazy.rb

require 'benchmark'

array = (1..1000).to_a

n = 1000
Benchmark.bmbm do |x|
  x.report("lazy")        { n.times { array.lazy.select(&:even?).map { |i| i / 2 }.to_a } }
  x.report("double-pass") { n.times { array.select(&:even?).map { |i| i / 2 } } }
  x.report("nested conditional") do
    n.times do
      [].tap do |evens|
        array.each do |i|
          next unless i.even?
          evens << i / 2
        end
      end
    end
  end
end
# >> 
# >>                          user     system      total        real
# >> lazy                 0.170447   0.000294   0.170741 (  0.170932)
# >> double-pass          0.060291   0.001461   0.061752 (  0.061843)
# >> nested conditional   0.055417   0.000347   0.055764 (  0.055812)

benchmark_lazy_by_steve.rb

require 'benchmark'

class Tray
  def initialize(n)
    @active = n % 3 != 1
  end

  def active?
    @active
  end
end

tray_count = 5400
trays = []

1.upto(tray_count) do |index|
  trays << Tray.new(index)
end

def do_something(tray)
  a = 1
  a + 1
end

n = 1000

Benchmark.bmbm(15) do |benchmark|
  benchmark.report("lazy") do
    n.times do
      trays.lazy.select(&:active?).each { |t| do_something(t) }
    end
  end

  benchmark.report("double pass") do
    n.times do
      trays.select(&:active?).each { |t| do_something(t) }
    end
  end

  benchmark.report("nested conditional") do
    n.times do
      trays.each do |t|
        next unless t.active?
        do_something(t)
      end
    end
  end
end
# >> 
# >>                          user     system      total        real
# >> lazy                 0.948223   0.001460   0.949683 (  0.950818)
# >> double pass          0.486718   0.003141   0.489859 (  0.490453)
# >> nested conditional   0.338364   0.000873   0.339237 (  0.339800)