From: brabuhr@...
Date: 2010-06-25T04:02:32+09:00
Subject: Re: Count substrings in string, scan too slow

On Thu, Jun 24, 2010 at 1:16 PM, Michael Fellinger
<m.fellinger@gmail.com> wrote:
> I've just run some benchmarks with strscan, and it's at least in the
> same ballpark as the other approaches, unless you're on rubinius, but
> then all string processing is really slow on that anyway.
>
> Benchmark with strscan here: http://gist.github.com/451675

http://en.literateprograms.org/Boyer-Moore_string_search_algorithm_%28Java%29

  require 'java'
  java_import 'BoyerMoore'

  x.report 'boyer_moore' do
    count = BoyerMoore.match("yo", s).size
    check count
  end

$ jruby -v yomark.rb
jruby 1.5.0 (ruby 1.8.7 patchlevel 249) (2010-05-12 6769999) (Java
HotSpot(TM) Client VM 1.6.0_20) [i386-java]
Rehearsal -----------------------------------------------
scan         22.423000   0.000000  22.423000 ( 22.334000)
scan ++      36.738000   0.000000  36.738000 ( 36.738000)
scan re      19.451000   0.000000  19.451000 ( 19.451000)
scan re ++   39.222000   0.000000  39.222000 ( 39.222000)
while        22.621000   0.000000  22.621000 ( 22.622000)
strscan      29.075000   0.000000  29.075000 ( 29.076000)
boyer_moore   0.009000   0.000000   0.009000 (  0.009000)
------------------------------------ total: 169.539000sec

                  user     system      total        real
scan         18.050000   0.000000  18.050000 ( 18.051000)
scan ++      35.046000   0.000000  35.046000 ( 35.046000)
scan re      17.807000   0.000000  17.807000 ( 17.807000)
scan re ++   34.086000   0.000000  34.086000 ( 34.085000)
while        22.089000   0.000000  22.089000 ( 22.089000)
strscan      29.538000   0.000000  29.538000 ( 29.538000)
boyer_moore   0.005000   0.000000   0.005000 (  0.004000)

$ jruby -v --server --fast yomark.rb
jruby 1.5.0 (ruby 1.8.7 patchlevel 249) (2010-05-12 6769999) (Java
HotSpot(TM) Server VM 1.6.0_20) [i386-java]
yobench.rb:50 warning: Useless use of a variable in void context.
Rehearsal -----------------------------------------------
scan         17.340000   0.000000  17.340000 ( 17.154000)
scan ++      23.986000   0.000000  23.986000 ( 23.987000)
scan re      15.170000   0.000000  15.170000 ( 15.169000)
scan re ++   22.805000   0.000000  22.805000 ( 22.806000)
while        12.050000   0.000000  12.050000 ( 12.050000)
strscan      31.396000   0.000000  31.396000 ( 31.396000)
boyer_moore   0.010000   0.000000   0.010000 (  0.010000)
------------------------------------ total: 122.756999sec

                  user     system      total        real
scan         15.201000   0.000000  15.201000 ( 15.201000)
scan ++      23.758000   0.000000  23.758000 ( 23.758000)
scan re      14.770000   0.000000  14.770000 ( 14.770000)
scan re ++   22.455000   0.000000  22.455000 ( 22.455000)
while        12.182000   0.000000  12.182000 ( 12.182000)
strscan      24.497000   0.000000  24.497000 ( 24.497000)
boyer_moore   0.002000   0.000000   0.002000 (  0.002000)