rubocop_benchmark

require 'benchmark'

actioncable_folder = '/rails/actioncable'
rubocop_folder = '/rubocop'

def reset_rails(actioncable_folder)
  Dir.chdir(actioncable_folder) do
    system('git checkout -f v5.2.3 >/dev/null 2>&1')
    system('mv ../.rubocop.yml ../.rubocop.yml_bk')
  end 
end 

def reset_rubocop(branch_name, rubocop_folder)
  Dir.chdir(rubocop_folder) do
    system("git checkout #{branch_name} >/dev/null 2>&1")
  end 
end

def do_rubocop(option, rubocop_folder, actioncable_folder)
  reset_rails(actioncable_folder)
  system("bundle exec ruby ./exe/rubocop #{actioncable_folder} #{option} >/dev/null 2>&1")
end

# small test
::Benchmark.bm(18) do |r|
  option = ' --auto-correct --parallel'
  Dir.chdir(rubocop_folder) do
    reset_rubocop("feature/auto_correct_support_parallel", rubocop_folder)

    # warmup
    do_rubocop(option, rubocop_folder, actioncable_folder)
    r.report("with parallel") { 10.times { do_rubocop(option, rubocop_folder, actioncable_folder) } }
  end

  option = ' --auto-correct'
  Dir.chdir(rubocop_folder) do
    reset_rubocop("feature/auto_correct_support_parallel", rubocop_folder)

    # warmup
    do_rubocop(option, rubocop_folder, actioncable_folder)
    r.report("without parallel") { 10.times { do_rubocop(option, rubocop_folder, actioncable_folder) } }
  end

  option = ' --auto-correct'
  Dir.chdir(rubocop_folder) do
    reset_rubocop("fffd4e6278ff47783b8055dcad00f01b67fff4ff", rubocop_folder)

    # warmup
    do_rubocop(option, rubocop_folder, actioncable_folder)
    r.report("origin/master") { 10.times { do_rubocop(option, rubocop_folder, actioncable_folder) } }
  end
end

The result

	user	system	total	real
with parallel	0.004295	0.019300	165.135620	( 65.099195 )
without parallel	0.003868	0.017207	95.377579	( 96.922844 )
origin/master	0.003889	0.018306	94.157648	( 95.972828 )