Benchmarking

1_basic_benchmark.rb

n = 1_000_000

start_time = Time.now
for i in 1..n; a = "1"; end
end_time = Time.now

puts "total time for the operation was #{end_time - start_time} seconds"

start_time = Time.now
n.times do; a = "1"; end
end_time = Time.now

puts "total time for the operation was #{end_time - start_time} seconds"

start_time = Time.now
1.upto(n) do ; a = "1"; end
end_time = Time.now

puts "total time for the operation was #{end_time - start_time} seconds"

2_block_benchmark.rb

n = 1_000_000

def benchmark(title = 'the operation')
  start_time = Time.now
  yield
  end_time = Time.now

  puts "total time for #{title} was #{end_time - start_time} seconds"
end

benchmark("for") { for i in 1..n; a = "1"; end }
benchmark("times") { n.times do; a = "1"; end }
benchmark("upto") { 1.upto(n) do ; a = "1"; end }

3_built_in_benchmark.rb

require 'benchmark'

n = 1_000_000

Benchmark.bm(5) do |b|
  b.report("for") { for i in 1..n; a = "1"; end }
  b.report("times") { n.times do; a = "1"; end }
  b.report("upto") { 1.upto(n) do ; a = "1"; end }
end

4_why_we_warm.rb

require 'benchmark'
require 'find'

Benchmark.bm do |b|
  b.report("fs_scan") { Find.find(File.expand_path('~/Library/Preferences')) { |f| } }
end

#          user     system      total        real
# fs_scan  0.010000   0.030000   0.040000 (  0.627269)

#          user     system      total        real
# fs_scan  0.000000   0.000000   0.000000 (  0.007788)

5_bmbm.rb

require 'benchmark'
require 'find'

Benchmark.bmbm do |b|
  b.report("fs_scan") { Find.find(File.expand_path('~/Library/Application Support')) { |f| } }
end




#Rehearsal 
#-------------------------------------------
#fs_scan   0.490000   1.830000   2.320000 ( 13.592359)
#---------------------------------- total: 2.320000sec
#
#              user     system      total        real
#fs_scan   0.440000   0.830000   1.270000 (  1.263131)

6_count_me_in.rb

require 'benchmark'

test_scores = 500.times.inject([]) {|acc, a| acc << rand(100)}

count = 1000

my_proc = Proc.new {|x| x.even? }

Benchmark.bm(14) do |x|
  x.report("map cached-proc") { count.times {test_scores.map(&my_proc)}}
  x.report("map proc") { count.times {test_scores.map(&:even?)}}
  x.report("map block") { count.times {test_scores.map {|n| n.even?}}}
end


# count = 1
#        user     system      total        real
# map proc   0.000000   0.000000   0.000000 (  0.000042)
# map block  0.000000   0.000000   0.000000 (  0.000047)


# count = 1000
#        user     system      total        real
# map-proc  0.010000   0.000000   0.010000 (  0.006569)
# map       0.000000   0.000000   0.000000 (  0.009616)

7_concat_string_surprise.rb

require 'benchmark'

string1 = "hello" * 1000
string2 = "world" * 1000

count = 1000

Benchmark.bmbm(10) do |b|
  b.report("+") {  count.times {string1 + string2} }
  b.report("interpolate") {  count.times {"#{string1}#{string2}" } }
  b.report("concat") {  count.times {string1 << string2 } }
end

# Rehearsal -----------------------------------------------
# +             0.000000   0.000000   0.000000 (  0.004151)
# interpolate   0.000000   0.000000   0.000000 (  0.002999)
# concat        0.010000   0.000000   0.010000 (  0.002928)
# -------------------------------------- total: 0.010000sec
# 
#                   user     system      total        real
# +             1.170000   0.470000   1.640000 (  1.645940)
# interpolate   1.570000   2.450000   4.020000 (  4.024045)
# concat        0.000000   0.010000   0.010000 (  0.005437)

8_sort_array.rb

require 'benchmark'

a, b, c = [], [], []

1_000_000.times { a << rand; b << rand; c << rand }

Benchmark.bmbm(12) do |x|
  x.report("sort") { a.sort }
  x.report("sort_by") { b.sort_by {|n| n} }
  x.report("sort!") { c.sort! }
  x.report("sort join split") { a.sort.join(",").split(",") }
end