Profile provides a way to Profile your Ruby application.

Profiling your program is a way of determining which methods are called and how long each method takes to complete. This way you can detect which methods are possible bottlenecks.

Profiling your program will slow down your execution time considerably, so activate it only when you need it. Don't confuse benchmarking with profiling.

There are two ways to activate Profiling:

Command line

Run your Ruby script with -rprofile:

ruby -rprofile example.rb

If you're profiling an executable in your $PATH you can use ruby -S:

ruby -rprofile -S some_executable

From code

Just require 'profile':

require 'profile'

def slow_method
  5000.times do
    9999999999999999*999999999
  end
end

def fast_method
  5000.times do
    9999999999999999+999999999
  end
end

slow_method
fast_method

The output in both cases is a report when the execution is over:

ruby -rprofile example.rb

  %   cumulative   self              self     total
 time   seconds   seconds    calls  ms/call  ms/call  name
 68.42     0.13      0.13        2    65.00    95.00  Integer#times
 15.79     0.16      0.03     5000     0.01     0.01  Fixnum#*
 15.79     0.19      0.03     5000     0.01     0.01  Fixnum#+
  0.00     0.19      0.00        2     0.00     0.00  IO#set_encoding
  0.00     0.19      0.00        1     0.00   100.00  Object#slow_method
  0.00     0.19      0.00        2     0.00     0.00  Module#method_added
  0.00     0.19      0.00        1     0.00    90.00  Object#fast_method
  0.00     0.19      0.00        1     0.00   190.00  #toplevel
Methods
P
S
Constants
PROFILE_CALL_PROC = TracePoint.new(*%i[call c_call b_call]) {|tp| # :nodoc: now = Process.times[0] stack = (@@stacks[Thread.current] ||= []) stack.push [now, 0.0] }
 
PROFILE_RETURN_PROC = TracePoint.new(*%i[return c_return b_return]) {|tp| # :nodoc: now = Process.times[0] key = Wrapper.new(tp.defined_class, tp.method_id) stack = (@@stacks[Thread.current] ||= []) if tick = stack.pop threadmap = (@@maps[Thread.current] ||= {}) data = (threadmap[key] ||= [0, 0.0, 0.0, key]) data[0] += 1 cost = now - tick[0] data[1] += cost data[2] += cost - tick[1] stack[-1][1] += cost if stack[-1] end }
 
Instance Public methods
print_profile(f)

Source: show | on GitHub 

# File lib/profiler.rb, line 110
def print_profile(f)
  stop_profile
  total = Process.times[0] - @@start
  if total == 0 then total = 0.01 end
  totals = {}
  @@maps.values.each do |threadmap|
    threadmap.each do |key, data|
      total_data = (totals[key] ||= [0, 0.0, 0.0, key])
      total_data[0] += data[0]
      total_data[1] += data[1]
      total_data[2] += data[2]
    end
  end

  # Maybe we should show a per thread output and a totals view?

  data = totals.values
  data = data.sort_by{|x| -x[2]}
  sum = 0
  f.printf "  %%   cumulative   self              self     total\n"
  f.printf " time   seconds   seconds    calls  ms/call  ms/call  name\n"
  for d in data
    sum += d[2]
    f.printf "%6.2f %8.2f  %8.2f %8d ", d[2]/total*100, sum, d[2], d[0]
    f.printf "%8.2f %8.2f  %s\n", d[2]*1000/d[0], d[1]*1000/d[0], d[3]
  end
  f.printf "%6.2f %8.2f  %8.2f %8d ", 0.0, total, 0.0, 1     # ???
  f.printf "%8.2f %8.2f  %s\n", 0.0, total*1000, "#toplevel" # ???
end
start_profile()

Source: show | on GitHub 

# File lib/profiler.rb, line 99
def start_profile
  @@start = Process.times[0]
  @@stacks = {}
  @@maps = {}
  PROFILE_CALL_PROC.enable
  PROFILE_RETURN_PROC.enable
end
stop_profile()

Source: show | on GitHub 

# File lib/profiler.rb, line 106
def stop_profile
  PROFILE_CALL_PROC.disable
  PROFILE_RETURN_PROC.disable
end