From: Matt Mower <matt.mower@...>
Date: 2005-04-30T22:43:50+09:00
Subject: Re: Performance of SyncEnumerator

As if often the case, pressing send made me think "why don't i just find out?"

On 4/30/05, Matt Mower <matt.mower@gmail.com> wrote:
> 
> The profiler shows the bad boys are:
> 
>   %   cumulative   self              self     total
>  time   seconds   seconds    calls  ms/call  ms/call  name
>  33.99     9.92      9.92    37772     0.26     0.26  Kernel.callcc
>  12.69    13.62      3.70     6118     0.61     9.94  Generator#next
>  10.91    16.81      3.18    12768     0.25     4.79  Generator#end?
>   9.97    19.72      2.91     6118     0.48     1.67  Generator#yield
>   8.68    22.25      2.53     3345     0.76    16.39  Array#map
>   6.84    24.24      2.00      266     7.50   200.63  Proc#call
> 

Re-implementing as:

    def euclidean_distance2( vector )
      sum = 0
      each_with_index { |value,index| sum += ( ( value - vector[index]
) ** 2 ) }
      Math.sqrt( sum )
    end

results in a profile of:

  %   cumulative   self              self     total
 time   seconds   seconds    calls  ms/call  ms/call  name
 40.16     1.59      1.59      300     5.31    23.34  Array#each
 10.68     2.02      0.42     1978     0.21     0.33  Fixnum#**
  5.95     2.25      0.24     2165     0.11     0.14  ART::Cluster#size
  4.76     2.44      0.19     4143     0.05     0.05  Fixnum#+
  4.71     2.63      0.19     3245     0.06     0.06  Array#[]
  3.12     2.75      0.12     1978     0.06     0.06  Fixnum#>=
  2.77     2.86      0.11     1978     0.06     0.06  Fixnum#power!

Total run-time is reduced from 29.19s to 3.97s (86% reduction).  

I guess the moral of this story (for me) is that SyncEnumerator is
neat but shouldn't be used where performance is important.

Regards,

Matt

-- 
Matt Mower :: http://matt.blogs.it/