From: Paul Brannan <pbrannan@...>
Date: 2008-04-23T03:46:06+09:00
Subject: Re: Performance on method dispatch for methods defined via define_method

On Wed, Apr 23, 2008 at 12:39:29AM +0900, Robert Dober wrote:
> to my dispair (because it makes traits slow) method lookup is about
> 50% slower for methods defined via define_method vs. def.
> If this is completely stupid a question just say so and sorry for
> having wasted your time, but here I go.

Why do you believe it is method lookup that is slower?  Your benchmark
tests both lookup and dispatch (I say this because I suspect it is the
dispatch that is slow).

> Would there be any chance to get the same speed for method
> lookup/invocation for methods defined via define_method?
> Right now we have this:

Method dispatch to a method defined with define_method is not much less
than the cost of calling a proc, which is essentially what's happening
under the hood:

[pbrannan@zaphod tmp]$ cat test.rb
require 'benchmark'

N=1_000_000

Benchmark::bmbm do |bm|
  p = proc { }
  o = Object.new
  osc = class << o; self; end
  osc.instance_eval {
    define_method(:foo, &p)
  }

  bm.report "define_method" do
    N.times { o.foo }
  end
  bm.report "proc.call" do
    N.times { p.call }
  end
end
[pbrannan@zaphod tmp]$ ruby1.9 -v test.rb
ruby 1.9.0 (2008-03-20 revision 0) [i686-linux]
Rehearsal -------------------------------------------------
define_method   1.090000   0.000000   1.090000 (  1.095923)
proc.call       1.210000   0.000000   1.210000 (  1.218726)
---------------------------------------- total: 2.300000sec

                    user     system      total        real
define_method   1.080000   0.020000   1.100000 (  1.106690)
proc.call       1.210000   0.000000   1.210000 (  1.219874)

To make methods defined with define_method faster, one would need to
make proc invocation faster.  I don't see any low-hanging fruit here,
though.  It's already much faster than 1.8:

[pbrannan@zaphod tmp]$ ruby -v test.rb
ruby 1.8.6 (2007-09-24 patchlevel 111) [i686-linux]
Rehearsal -------------------------------------------------
define_method   3.190000   0.000000   3.190000 (  3.196841)
proc.call       3.250000   0.010000   3.260000 (  3.255551)
---------------------------------------- total: 6.450000sec

                    user     system      total        real
define_method   3.210000   0.000000   3.210000 (  3.210368)
proc.call       3.280000   0.000000   3.280000 (  3.284931)

Paul