ruby command execution

benchmark.rb

#!/usr/bin/env ruby

require 'benchmark'
require 'childprocess'
require 'systemu'

argv = %w[git rev-parse HEAD^{commit}]
args = argv.join(" ")

COUNT = 100

Benchmark.bmbm do |b|

  b.report("%x") do
    COUNT.times { _ = %x(#{args}) }
  end

  b.report("system") do
    COUNT.times { _ = system("#{args} >/dev/null") }
  end

  b.report("childprocess") do
    COUNT.times do
      process = ChildProcess.build(*argv)


      stdout_r, stdout_w = IO.pipe
      stderr_r, stderr_w = IO.pipe

      process.duplex = true
      process.io.stdout = stdout_w
      process.io.stderr = stderr_w

      process.cwd = Dir.getwd

      process.start
      process.wait

      stdout_w.close
      stderr_w.close

      stdout = ""
      stdout << stdout_r.read_nonblock(1 << 12) until stdout_r.eof?
    end
  end

  b.report("systemu") do
    COUNT.times { status, out, err = systemu(args) }
  end
end

benchmark.txt

Executing "git rev-parse HEAD^{commit}" 100 times
Rehearsal ------------------------------------------------
%x             0.010000   0.040000   0.260000 (  0.325595)
system         0.000000   0.030000   0.160000 (  0.295756)
childprocess   0.000000   0.040000   0.140000 (  0.173006)
systemu        0.080000   0.050000  19.800000 ( 19.873185)
-------------------------------------- total: 20.360000sec

                   user     system      total        real
%x             0.010000   0.040000   0.250000 (  0.295944)
system         0.010000   0.030000   0.180000 (  0.301151)
childprocess   0.010000   0.040000   0.150000 (  0.175649)
systemu        0.060000   0.070000  19.740000 ( 19.797458)