Profiling and benchmarking tools like perftools.rb, Benchmark, and ruby-prof can help optimize Ruby code by identifying slow parts. These tools sample programs to measure CPU time, memory usage, and other metrics. Benchmark allows basic timing comparisons, while profilers like perftools.rb and ruby-prof provide call graphs and other visualizations to pinpoint where to optimize. These techniques help focus optimization efforts on the most impactful areas.

1. Profiling Ruby
Where and what to optimize in your code
/
jobs@housetrip.com /
Nasir Jamal work@HouseTrip
@_nasj

2. profiling helps you to narrow down to
where optimization would be most useful

3. benchmarking allows you to easily isolate
optimizations and cross-compare them

4. Benchmarking

5. Realtime
puts Benchmark.realtime { 4000.times { |x| x**x } }
#=> 0.905972957611084

6. 1. User CPU time
2. System CPU time
3. (1 + 2) i.e. User + System CPU time
4. Realtime
puts Benchmark.measure { 4000.times { |x| x**x } }
# => 0.890000 0.020000 0.910000 (0.909118)

7. Benchmark.bm do |bm|
bm.report { first_algorithm }
bm.report { second_algorithm}
…..
end
#=> user system total real
0.940000 0.010000 0.950000 ( 0.956572)
0.430000 0.010000 0.440000 ( 0.423467)

8. Benchmark.bm(14) do |bm|
bm.report(“first header”) { first_algorithm }
bm.report(“second header”) { second_algorithm}
…..
end
#=> user system total real
first header 0.940000 0.010000 0.950000 (0.956572)
second header 0.430000 0.010000 0.440000 (0.423467)

9. examples ...

10. Benchmark.bmbm(20) do |bm|
bm.report('append') do
str1, str2, str3, str4 = 'string1', 'string2', 'string3', 'string4'
1_000_000.times { y = str1 << str2 << str3 << str4 }
end
bm.report('concat') do
str1, str2, str3, str4 = 'string1', 'string2', 'string3', 'string4'
1_000_000.times { y = str1 + str2 + str3 + str4 }
end
bm.report('interpolate') do
str1, str2, str3, str4 = 'string1', 'string2', 'string3', 'string4'
1_000_000.times { y = "#{str1}#{str2}#{str3}#{str4}" }
end
bm.report('interpolate one') do
str1, str2, str3, str4 = 'string1', 'string2', 'string3', 'string4'
1_000_000.times { y = "string1string2string3#{str4}" }
end
end
.bmbm prevents result skewing

11. bmbm does rehearsal which includes any initialisation and GC run
then it does the real benchmark
#=> Rehearsal ---------------------------------------------
append 0.280000 0.000000 0.280000 ( 0.294505)
concat 0.470000 0.020000 0.490000 ( 0.481748)
interpolate 0.430000 0.010000 0.440000 ( 0.433404)
interpolate one 0.320000 0.000000 0.320000 ( 0.323479)
--------------------------------------- total: 1.530000sec
| Tests | user | system | total | real |
|:---------------|:--------:|:--------:|:---------:|-----------:|
|append | 0.260000 | 0.010000 | 0.270000 | (0.265732) |
|concat | 0.400000 | 0.010000 | 0.410000 | (0.396115) |
|interpolate | 0.400000 | 0.000000 | 0.400000 | (0.408096) |
|interpolate one | 0.280000 | 0.010000 | 0.290000 | (0.286443) |

12. Benchmark.bmbm(20) do |bm|
bm.report('gsub') do
1_0_000.times { Date.today.to_s.gsub!('-','') }
end
bm.report('strftime') do
1_0_000.times { Date.today.strftime("%Y%m%d") }
end
end
#=> Rehearsal -------------------------------------------
gsub 0.750000 0.000000 0.750000 ( 0.751547)
strftime 1.320000 0.000000 1.320000 ( 1.320621)
------------------------------------ total: 2.070000sec
| | user | system | total | real |
|:--------|:--------:|:---------:|:--------:|:-----------|
|gsub | 0.710000 | 0.000000 | 0.710000 | (0.709918) |
|strftime | 1.320000 | 0.000000 | 1.320000 | (1.315345) |

13. module Extendable
def name
@name
end
end
class Person
attr_accessor :name
end
require 'ostruct'
Benchmark.bmbm(20) do |bm|
bm.report('Class') do
1_00_000.times { p = Person.new; p.name='Joe'; p.name }
end
bm.report('Extends') do
1_00_000.times { p = Person1.new; p.extend Extendable; p.name='Joe'; p.name }
end
bm.report('Struct') do
1_00_000.times { person2 = Struct.new(:name); p = person2.new('Joe'); p.name }
end
bm.report('OpenStruct') do
1_00_000.times { p = OpenStruct.new(:name => 'Joe'); p.name }
end
end

14. #=> Rehearsal ---------------------------------------------
Class 0.080000 0.000000 0.080000 (0.086261)
Extends 0.410000 0.000000 0.410000 (0.407723)
Struct 1.490000 0.000000 1.490000 (1.490557)
OpenStruct 1.980000 0.010000 1.990000 (1.990507)
------------------------------------ total: 3.970000sec
| | user | system | total | real |
|:----------|:--------:|:--------:|:---------:|:-----------|
|Class | 0.080000 | 0.000000 | 0.080000 | (0.082448) |
|Extends | 0.400000 | 0.000000 | 0.400000 | (0.410884) |
|Struct | 1.480000 | 0.000000 | 1.480000 | (1.490531) |
|OpenStruct | 1.960000 | 0.010000 | 1.970000 | (1.965923) |

15. Profiling

16. perftools.rb
an adaptation of Google's perftools library to the Ruby land by Aman
Gupta
https://github.com/tmm1/perftools.rb
$gem install perftools.rb

17. does profiling via sampling method, where by default it takes
100 samples a second

18. examples ...

19. to see results
Interpreting the above columns:
1. Number of profiling samples in this function
2. Percentage of profiling samples in this function
3. Percentage of profiling samples in the functions printed so far
4. Number of profiling samples in this function and its callees
5. Percentage of profiling samples in this function and its callees
6. Function name
a = ''
PerfTools::CpuProfiler.start("/tmp/profiling/string_concat") do
100_000.times {|x| a += x.to_s}
end
$pprof.rb --text --ignore=Gem /tmp/profiling/string_concat
Total: 2939 samples
1497 50.9% 50.9% 1501 51.1% Object#irb_binding
1438 48.9% 99.9% 1438 48.9% garbage_collector
4 0.1% 100.0% 1500 51.0% Integer#times

20. to see results as graph
bigger the box, the more time spent there
1. Class Name
2. Method Name
3. local (percentage)
4. of cumulative (percentage)
brew install graphviz
$pprof.rb --gif --ignore=Gem /tmp/profiling/string_concat > /tmp/profiling/string_concat.gif

21. slightly hairy method
And on on ....
PerfTools::CpuProfiler.start("/tmp/profiling/property_search") do
100.times { PropertySearch.new.search }
end
$pprof.rb --text --ignore=Gem /tmp/profiling/property_search
Total: 6799 samples
2598 38.2% 38.2% 2598 38.2% garbage_collector
1761 25.9% 64.1% 3966 58.3% PropertySearch#set_price_filter_counts
390 5.7% 69.8% 1632 24.0% Object#detect
389 5.7% 75.6% 503 7.4% PropertySearch::PriceRange#contains?
358 5.3% 80.8% 358 5.3% Mysql2::Result#each
263 3.9% 84.7% 768 11.3% Object#select_values
199 2.9% 87.6% 236 3.5% ActiveRecord::ConnectionAdapters::Mysql2Adapter#execu
187 2.8% 90.4% 640 9.4% Property.collect_column
148 2.2% 92.6% 148 2.2% ActiveSupport::BufferedLogger#flush
114 1.7% 94.2% 114 1.7% Fixnum#<=
75 1.1% 95.3% 75 1.1% Array#join
67 1.0% 96.3% 76 1.1% Array#map
47 0.7% 97.0% 47 0.7% ActiveRecord::ConnectionAdapters::Column#type_cast
44 0.6% 97.7% 295 4.3% Array#collect
32 0.5% 98.1% 388 5.7% Object#to_a
28 0.4% 98.5% 28 0.4% PropertySearch#day_count
15 0.2% 98.8% 140 2.1% ActiveRecord::ConnectionAdapters::Mysql2Adapter#selec
9 0.1% 98.9% 4199 61.8% PropertySearch#search

23. $pprof.rb --help

24. Qcachegrind
How to setup?
http://langui.sh/2011/06/16/how-to-install-qcachegrind-
kcachegrind-on-mac-osx-snow-leopard/

25. $pprof.rb --callgrind /tmp/profiling/property_search > /tmp/profiling/property_search.callgr

26. graph

27. To use with Rails
Valid default_printer values are pdf, text, raw, gif, callgrind
# Gemfile
gem 'rack-perftools_profiler', :require => false
# config/environment.rb
config.middleware.use ::Rack::PerftoolsProfiler,
:default_printer => 'gif',
:bundler => true,
:mode => :cputime,
:frequency => 250

28. profile=true will enable profiling
times=10 will hit the page for 10 times
will store the results in profile_ppp_page.txt
RACK_PROFILER=true script/server
curl -o profile_ppp_page.txt
"http://localhost:3000/en/rentals/107605?profile=true&times=10"

30. ruby-prof
OR
$gem install ruby-prof
#Gemfile
gem 'ruby-prof', :require => false

31. types of measures
RubyProf.measure_mode = RubyProf::PROCESS_TIME
RubyProf.measure_mode = RubyProf::WALL_TIME
RubyProf.measure_mode = RubyProf::CPU_TIME
RubyProf.measure_mode = RubyProf::ALLOCATIONS
RubyProf.measure_mode = RubyProf::MEMORY
RubyProf.measure_mode = RubyProf::GC_RUNS
RubyProf.measure_mode = RubyProf::GC_TIME

32. types of printers
RubyProf::FlatPrinter
RubyProf::FlatPrinterWithLineNumbers
RubyProf::GraphPrinter
RubyProf::GraphHtmlPrinter
RubyProf::CallTreePrinter
RubyProf::CallStackPrinter
RubyProf::MultiPrinter

33. examples ...

34. GraphHtmlPrinter
result = RubyProf.profile { PropertySearch.new.search }
printer = RubyProf::GraphHtmlPrinter.new(result)
File.open("tmp/profile_data.html", 'w') { |file| printer.print(file)}

35. profile_data.html

36. CallStackPrinter
result = RubyProf.profile { PropertySearch.new.search }
printer = RubyProf::CallStackPrinter.new(result)
File.open("tmp/profile_data.html", 'w') { |file| printer.print(file)}

37. profile_data.html

38. CallTreePrinter
result = RubyProf.profile { PropertySearch.new.search }
printer = RubyProf::CallTreePrinter.new(result)
File.open("tmp/profile_data", 'w') { |file| printer.print(file)}

39. profile_data (qcachegrind)

40. In Rails
2.x.x
3.x.x
Or just use rake tasks
script/performance/benchmarker 10 'Class.method_name' 'AnotherClass.method_name'
script/performance/profiler 'Class.method_name' 10 graph
script/performance/profiler 'Class.method_name' 10 graph_html 2> property.html && open prope
rails benchmarker 'Class.method_name'
rails profiler 'Class.method_name' --runs 3 --metrics cpu_time,memory
rake test:benchmark
rake test:profile
rake test:profile TEST=test/performance/home_page_test.rb

41. But from Rails 4.0
performance tests are no longer part of the default
stack
https://github.com/rails/rails-perftest

42. Questions?

43. jobs@housetrip.com
We are hiring

44. Thank you