a_bit_better.rb

require 'ruby-prof'

def profile_as(name)

  if ENV['PROFILE']

    RubyProf.start
    yield

    result = RubyProf.stop

    printer = RubyProf::CallTreePrinter.new(result)
    printer.print(:path => '.', :profile => name)
  else
    yield
  end

end

def get_hash
  output = {}
  (1..10_000).each {|num| output[num] = num*2}
  output
end

profile_as('better') do
  the_hash = get_hash
  (1..10_000).map do |num|
    the_hash[num].to_f
  end.map do |num|
    num.to_s
  end
end

best.callgrind.out.51741

events: wall_time

fl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
fn=Enumerator::Generator#initialize
0 3

fl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
fn=Enumerator::Lazy#map
0 14
cfl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
cfn=Enumerator::Generator#initialize
calls=2 30
30 3

fl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
fn=Enumerable#lazy
0 4

fl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
fn=Range#each
0 3039

fl=/Users/mauclair/Documents/profiling_preso/hurray.rb
fn=Object#get_hash
20 4
cfl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
cfn=Range#each
calls=1 22
22 3039

fl=/Users/mauclair/Documents/profiling_preso/hurray.rb
fn=Object#profile_as
8 43
cfl=/Users/mauclair/Documents/profiling_preso/hurray.rb
cfn=Object#get_hash
calls=1 27
27 3043
cfl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
cfn=Enumerable#lazy
calls=1 28
28 4
cfl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
cfn=Enumerator::Lazy#map
calls=2 28
28 17

better.callgrind.out.51538

events: wall_time

fl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
fn=Float#to_s
0 7509

fl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
fn=Array#map
0 3670
cfl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
cfn=Float#to_s
calls=10000 31
31 7509

fl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
fn=Integer#to_f
0 1741

fl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
fn=Enumerable#map
0 4
cfl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
cfn=Range#each
calls=1 28
28 5643

fl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
fn=Range#each
0 7122
cfl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
cfn=Integer#to_f
calls=10000 29
29 1741

fl=/Users/mauclair/Documents/profiling_preso/a_bit_better.rb
fn=Object#get_hash
20 3
cfl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
cfn=Range#each
calls=1 22
22 3220

fl=/Users/mauclair/Documents/profiling_preso/a_bit_better.rb
fn=Object#profile_as
8 41
cfl=/Users/mauclair/Documents/profiling_preso/a_bit_better.rb
cfn=Object#get_hash
calls=1 27
27 3223
cfl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
cfn=Enumerable#map
calls=1 28
28 5647
cfl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
cfn=Array#map
calls=1 28
28 11179

config.ru

# This file is used by Rack-based servers to start the application.

require ::File.expand_path('../config/environment', __FILE__)

# Action Cable requires that all classes are loaded in advance
Rails.application.eager_load!

run Rails.application

if ENV['PROFILE']
  require 'ruby-prof'
  use Rack::RubyProf, :path => 'tmp/profile', :printers => [RubyProf::CallTreePrinter], :request_thread_only => true
end

development.rb

# SNIP
config.cache_classes = !ENV[‘PROFILE’]
# Do not eager load code on boot.
config.eager_load = !ENV[‘PROFILE’]
# SNIP

file_to_profile.rb

require 'ruby-prof'

# profile the code
RubyProf.start
# ... code to profile ...
result = RubyProf.stop

printer = RubyProf::CallTreePrinter.new(result)
printer.print(:path => Rails.root.join("tmp"), :profile => "profile")

hurray.rb

require 'ruby-prof'

def profile_as(name)

  if ENV['PROFILE']

    RubyProf.start
    yield

    result = RubyProf.stop

    printer = RubyProf::CallTreePrinter.new(result)
    printer.print(:path => '.', :profile => name)
  else
    yield
  end

end

def get_hash
  output = {}
  (1..10_000).each {|num| output[num] = num*2}
  output
end

profile_as('best') do
  the_hash = get_hash
  (1..10_000).lazy.map do |num|
    the_hash[num].to_f
  end.map do |num|
    num.to_s
  end
end

oh_no.rb

require 'ruby-prof'

def profile_as(name)

  if ENV['PROFILE']

    RubyProf.start
    yield

    result = RubyProf.stop

    printer = RubyProf::CallTreePrinter.new(result)
    printer.print(:path => '.', :profile => name)
  else
    yield
  end

end

def get_hash
  output = {}
  (1..10_000).each {|num| output[num] = num*2}
  output
end

profile_as('real_bad') do
  (1..10_000).map do |num|
    get_hash[num].to_f
  end.map do |num|
    num.to_s
  end
end

real_bad.callgrind.out.51306

events: wall_time

fl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
fn=Float#to_s
0 5164

fl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
fn=Array#map
0 3526
cfl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
cfn=Float#to_s
calls=10000 30
30 5164

fl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
fn=Integer#to_f
0 8243

fl=/Users/mauclair/Documents/profiling_preso/oh_no.rb
fn=Object#get_hash
20 18703
cfl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
cfn=Range#each
calls=10000 22
22 26076196

fl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
fn=Range#each
0 23690
cfl=/Users/mauclair/Documents/profiling_preso/oh_no.rb
cfn=Object#get_hash
calls=10000 28
28 26094899
cfl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
cfn=Integer#to_f
calls=10000 28
28 8243

fl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
fn=Enumerable#map
0 3
cfl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
cfn=Range#each
calls=1 27
27 26126832

fl=/Users/mauclair/Documents/profiling_preso/oh_no.rb
fn=Object#profile_as
8 35
cfl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
cfn=Enumerable#map
calls=1 27
27 26126835
cfl=/Users/mauclair/Documents/profiling_preso/ruby_runtime
cfn=Array#map
calls=1 27
27 8690