a multi-dimensional Ruby benchmark script :-)

benchmark.rb

#!/usr/bin/env ruby
#
# NAME
#
#   benchmark.rb -- a multi-dimensional Ruby benchmark script :-)
#
# DESCRIPTION
#
#   a customized Ruby "interpreter" that benchmarks
#   other Ruby scripts... by default, both resident
#   memory usage and elapsed time are measured, and
#   reported to the console;  adding other measures
#   and changing the reporting units is easy to do!
#
# USAGE
#
#   Ensure `benchmark.rb` has execute perms:
#
#       chmod a+x benchmark.rb
#
#   In order to benchmark another Ruby script,
#   change its shebang line to something like:
#
#       #!/usr/bin/env ./benchmark.rb
#
#   Alternatively run this script directly by
#   by adding the Ruby script as an argument:
#
#       ./benchmark.rb some_other_script.rb
#
# NOTES
#
#   the elapsed real time can be much better measured using
#   Ruby's standard "benchmark" library;  to illustrate how
#   multiple measures can be nested and reported, though,
#   this script measures it directly, albeit more naively
#

# the real memory (resident set) size of the process (in 1024 byte units).
def Process.rss ; `ps -o rss= -p #{Process.pid}`.chomp.to_i ; end

# determine a measure (by calling the proc)
# before & after running the block of code
def measure measure_name, measure_proc
  before = measure_proc.call ; warn "(#{__FILE__}) #{measure_name} - before: #{before}" if $DEBUG
  yield if block_given?
  after = measure_proc.call ; warn "(#{__FILE__}) #{measure_name} - after: #{after}" if $DEBUG
  [before, after].tap { |result|
    class << result
      alias_method :before, :first
      alias_method :after, :last
    end
  }
end

# default measures: resident memory and elapsed time
rss = tms = nil

# do it...
rss = measure("RSS", -> { Process.rss }) do
  tms = measure("Time", -> { Time.now }) do
    # GC.disable # uncomment to get "true" picture of memory usage/increase
    warn "(#{__FILE__}) running '#{ARGV.first}'" if $DEBUG
    load ARGV.shift # run the actual Ruby script
  end
end

# print out the measures...
warn ""
warn "(#{__FILE__}) Memory usage/increase - %s kilobytes" % (rss.after - rss.before)
warn "(#{__FILE__}) Elapsed real time     - %.2f seconds" % (tms.after - tms.before)

# That's all, Folks!