Ruby micro-benchmark for static vs. dynamic dispatch

benchmark.rb

#!/usr/bin/env ruby

require 'benchmark'

class StaticDispatch

  def dispatch
    if rand > 0.5
      method1
    else
      method2
    end
  end

  def method1
    1
  end

  def method2
    2
  end

end

class DynamicDispatch

  def dispatch
    i = if rand > 0.5
          1
        else
          2
        end

    send("method#{i}")
  end

  def method1
    1
  end

  def method2
    2
  end

end

Benchmark.bm do |b|
  n = 1_000_000

  b.report('static dispatch') do
    obj = StaticDispatch.new

    n.times do
      obj.dispatch
    end
  end

  b.report('dynamic dispatch') do
    obj = DynamicDispatch.new

    n.times do
      obj.dispatch
    end
  end
end

benchmark_with_symbols.rb

#!/usr/bin/env ruby

require 'benchmark'

class StaticDispatch

  def dispatch
    if rand > 0.5
      method1
    else
      method2
    end
  end

  def method1
    1
  end

  def method2
    2
  end

end

class DynamicDispatch

  def dispatch
    method = if rand > 0.5
          :method1
        else
          :method2
        end

    send(method)
  end

  def method1
    1
  end

  def method2
    2
  end

end

Benchmark.bm do |b|
  n = 1_000_000

  b.report('static dispatch') do
    obj = StaticDispatch.new

    n.times do
      obj.dispatch
    end
  end

  b.report('dynamic dispatch') do
    obj = DynamicDispatch.new

    n.times do
      obj.dispatch
    end
  end
end

and if you were wondering if the overhead was due to String building, dynamic dispatch with Symbols is 2x slower:

       user     system      total        real
static dispatch  0.146822   0.000000   0.146822 (  0.151365)
dynamic dispatch  0.244416   0.000000   0.244416 (  0.245730)