Measure and Benchmark Time for Ruby Methods

Question

How can i measure the time taken by a method and the individual statements in that method in Ruby. If you see the below method i want to measure the total time taken by the method and the time taken for database access and redis access. I do not want to write Benchmark.measure before every statement. Does the ruby interpreter gives us any hooks for doing this ?

def foo
# code to access database
# code to access redis. 
end

there is something similar to the `new Date()` of javascript that ruby has, but I can't remember the correct syntax. should give you a decent google listing though — reagan, Jul 10 '12 at 04:03
@Phani Can you select a correct answer please? After 8 years, I think there are some solid answers here. Thanks. — Joshua Pinter, May 26 '20 at 15:02

wquist · Answer 1 · 2012-07-10T12:53:52.967

117

You could use the Time object. (Time Docs)

For example,

start = Time.now
# code to time
finish = Time.now

diff = finish - start

diff would be in seconds, as a floating point number.

EDIT: end is reserved.

edited Jul 10 '12 at 12:53

answered Jul 10 '12 at 04:10

wquist

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just a minor correction. `end` is reserved, so use some other variable name. – Jason Kim Jul 10 '12 at 04:56
5

`Time.now` is affected by adjustments to the system clock, so it's a best practice to use `Process.clock_gettime(Process::CLOCK_MONOTONIC)` instead. But for rough calculations this doesn't matter. https://blog.dnsimple.com/2018/03/elapsed-time-with-ruby-the-right-way/ – Patrick Brinich-Langlois Feb 21 '19 at 19:13

score 115 · Answer 2 · edited Oct 30 '15 at 15:07

115

The simplest way:

require 'benchmark'

def foo
 time = Benchmark.measure {
  code to test
 }
 puts time.real #or save it to logs
end

Sample output:

2.2.3 :001 > foo
  5.230000   0.020000   5.250000 (  5.274806)

Values are: cpu time, system time, total and real elapsed time.

Source: ruby docs.

edited Oct 30 '15 at 15:07

fernandohur

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answered Mar 20 '15 at 12:26

Łukasz Ostrowski

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45

You can also do `Benchmark.realtime { block }` if you just want the realtime – jmccure Jun 26 '15 at 11:34

Joshua Pinter · Answer 3 · 2020-07-06T20:47:46.360

43

Use `Benchmark`'s Report

require 'benchmark' # Might be necessary.

def foo
  Benchmark.bm( 20 ) do |bm|  # The 20 is the width of the first column in the output.
    bm.report( "Access Database:" ) do 
      # Code to access database.
    end
   
    bm.report( "Access Redis:" ) do
      # Code to access redis.
    end
  end
end

This will output something like the following:

                        user     system      total        real
Access Database:    0.020000   0.000000   0.020000 (  0.475375)
Access Redis:       0.000000   0.000000   0.000000 (  0.000037)

<------ 20 -------> # This is where the 20 comes in. NOTE: This is not shown in output.

More information can be found here.

edited Jul 06 '20 at 20:47

answered Oct 13 '16 at 18:30

Joshua Pinter

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I just came back to my own answer and was impressed (again) with how Benchmark handles this. Love Ruby. – Joshua Pinter Feb 24 '17 at 15:19
3

This should be the preferred answer: Because, as of Ruby 2.2, the `Benchmark` class uses a monotonic clock, as discussed in other answers. See for instance the following source code, and look for "def measure" on line 286: https://github.com/ruby/ruby/blob/ruby_2_2/lib/benchmark.rb – Purplejacket Apr 19 '19 at 21:51

Guy C · Answer 4 · 2019-02-01T02:41:59.407

Many of the answers suggest the use of Time.now. But it is worth being aware that Time.now can change. System clocks can drift and might get corrected by the system's administrator or via NTP. It is therefore possible for Time.now to jump forward or back and give your benchmarking inaccurate results.

A better solution is to use the operating system's monotonic clock, which is always moving forward. Ruby 2.1 and above give access to this via:

start = Process.clock_gettime(Process::CLOCK_MONOTONIC)
# code to time
finish = Process.clock_gettime(Process::CLOCK_MONOTONIC)
diff = finish - start # gets time is seconds as a float

You can read more details here. Also you can see popular Ruby project, Sidekiq, made the switch to monotonic clock.

Houcheng · Answer 5 · 2018-06-06T14:33:45.257

7

A second thought, define the measure() function with Ruby code block argument can help simplify the time measure code:

def measure(&block)
  start = Time.now
  block.call
  Time.now - start
end

# t1 and t2 is the executing time for the code blocks.
t1 = measure { sleep(1) }

t2 = measure do
  sleep(2)
end

edited Jun 06 '18 at 14:33

answered Apr 17 '18 at 06:24

Houcheng

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In your definition you call it `benchmark`. When you use it it is called `measure`. Please fix this. – Sandro L May 30 '18 at 07:08

score 2 · Answer 6 · edited Mar 15 '15 at 15:39

2

In the spirit of wquist's answer, but a little simpler, you could also do it like below:

start = Time.now
# code to time
Time.now - start

edited Mar 15 '15 at 15:39

Jeffrey Bosboom

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answered Mar 15 '15 at 15:14

ADude2

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This answer is a (slightly) different way to answer the question. Just because you could figure it out from @wquist's answer doesn't mean it isn't valid. – thesecretmaster Jun 15 '18 at 21:22

Measure and Benchmark Time for Ruby Methods

6 Answers6

Use `Benchmark`'s Report

Linked

Measure and Benchmark Time for Ruby Methods

6 Answers6

Use Benchmark's Report

Linked

Use `Benchmark`'s Report