Respond_to? vs include?

Edoardo_R · March 31, 2013, 11:55pm

Hi everybody…

I wrote a fancy and very humble benckmark test to see which is faster
between respond_to? and include?..
The script is here:

https://gist.github.com/zeroed/5282125

But I’m not so confident with the result… if someone have 3min to
lose reading my script, can tell me if I’m completly missing the point
in such kind of test?
Maybe there is some improvements that needs to be done.

Thank you so much in advance…

e.

Edoardo_R · April 1, 2013, 12:08am

Your benchmark looks okay. I added a comment to your Gist about a fork
I made that shows the O(n) behaviour of include? versus the
constant-time behaviour of respond_to? by just tweaking your code.

Edoardo_R · April 1, 2013, 8:27am

On Mon, Apr 1, 2013 at 12:07 AM, Adam P. [email protected]
wrote:

Your benchmark looks okay. I added a comment to your Gist about a fork
I made that shows the O(n) behaviour of include? versus the
constant-time behaviour of respond_to? by just tweaking your code.

Thank you so much Adam.
Very interesting… appreciated.

e.

Edoardo_R · April 3, 2013, 7:33pm

On Mon, Apr 1, 2013 at 8:26 AM, Edoardo R. [email protected]
wrote:

On Mon, Apr 1, 2013 at 12:07 AM, Adam P. [email protected] wrote:

Your benchmark looks okay. I added a comment to your Gist about a fork
I made that shows the O(n) behaviour of include? versus the
constant-time behaviour of respond_to? by just tweaking your code.

Yeah, Array lookup is O(n) - that’s what one would expect. But the
Array
creation has overhead as well.

Thank you so much Adam.

Very interesting… appreciated.

I think the situation is more dramatic: for a single method test the
#instance_methods call needs to be included.

gist.github.com

https://gist.github.com/rklemme/5299235

respond_to_vs_include.rb

# Fancy benchmark...
# is respond_to? so faster than include?

require 'benchmark'

n = 10_000_000
mock_methods = ('a'..'z').to_a

class Mock
end

This file has been truncated. show original

times.txt

$ ruby respond_to_vs_include-RK.rb
                                               user     system      total        real
respond_to?:                               1.170000   0.000000   1.170000 (  1.167067)
include?:                                  7.862000   0.000000   7.862000 (  7.880450)
instance_methods.include?:               152.242000   0.000000 152.242000 (152.295711)

Kind regards

robert

Edoardo_R · April 3, 2013, 8:15pm

On 3 Apr 2013 08:49, “Robert K.” [email protected] wrote:

Yeah, Array lookup is O(n) - that’s what one would expect. But the Array
creation has overhead as well.

Good catch. Definitely a painful way to implement respond_to? !

Edoardo_R · April 3, 2013, 7:48pm

On Wed, Apr 3, 2013 at 9:48 AM, Robert K.
[email protected] wrote:

Modified version which compares the single method check times (which need to include Mock.instance_methods(false)). · GitHub

Kind regards

robert

–
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

Considerably more dramatic!
Thank you so much Robert for pointed that out…

eddie.