From: John Carter <john.carter@...>
Date: 2005-12-21T08:14:13+09:00
Subject: =~ vs match - Some benchmarks.

While profiling some code I noticed =~, String.match and Regexp.match
turning up in my hotspots. So here is the results of a little
benchmarking to resolve which is faster to use...

require 'benchmark'

n = 3000000
toad  = "frogs"
regex   = /frogs/
regexo  = /frogs/o

line = "as fun as looking for frogs in custard"
puts "string='#{line}'"
puts "regex=#{regex}"

Benchmark.bm(20) do |x|
   x.report("string=~/frogs/o"   ) { for i in 1..n; line  =~ /frogs/o  ; end }
   x.report("string=~/frogs/"    ) { for i in 1..n; line  =~ /frogs/   ; end }
   x.report("string=~/\#{toad}/o") { for i in 1..n; line  =~ /#{toad}/o; end }
   x.report("string=~regex"      ) { for i in 1..n; line  =~ regex     ; end }
   x.report("regex=~string"      ) { for i in 1..n; regex =~ line      ; end }
   x.report("string=~regexo"     ) { for i in 1..n; line  =~ regexo    ; end }
   x.report("string=~/\#{toad}/" ) { for i in 1..n; line  =~ /#{toad}/ ; end }
   x.report("regex.match"        ) { for i in 1..n; regex.match(line)  ; end }
   x.report("string.match"       ) { for i in 1..n; line.match(regex)  ; end }
end

Results on a P4 2.66Ghz using ruby-1.8.3...

string='as fun as looking for frogs in custard'
regex=(?-mix:frogs)
                           user     system      total        real
string=~/frogs/o      4.390000   1.170000   5.560000 (  5.936591)
string=~/frogs/       4.390000   1.160000   5.550000 (  6.922374)
string=~/#{toad}/o    4.450000   1.130000   5.580000 (  7.111464)
string=~regex         4.850000   1.100000   5.950000 (  8.030837)
regex=~string         4.690000   1.150000   5.840000 (  7.055707)
string=~regexo        5.000000   1.120000   6.120000 (  6.471198)
string=~/#{toad}/    23.750000   1.290000  25.040000 ( 28.654952)
regex.match           7.180000   1.180000   8.360000 (  9.444980)
string.match          7.950000   1.170000   9.120000 (  9.726876)

Results on same machine, using an "all optimization on" version of
ruby-1.9 (CVS version)...

string='as fun as looking for frogs in custard'
regex=(?-mix:frogs)
                           user     system      total        real
string=~/frogs/o      1.950000   0.000000   1.950000 (  2.005067)
string=~/frogs/       1.960000   0.010000   1.970000 (  2.000758)
string=~/#{toad}/o    2.070000   0.000000   2.070000 (  2.150130)
string=~regex         2.120000   0.000000   2.120000 (  2.199664)
regex=~string         2.150000   0.000000   2.150000 (  2.284082)
string=~regexo        2.230000   0.010000   2.240000 (  2.337823)
string=~/#{toad}/    12.580000   0.040000  12.620000 ( 14.492860)
regex.match           3.870000   0.010000   3.880000 (  5.636765)
string.match          4.800000   0.010000   4.810000 (  5.903205)




John Carter                             Phone : (64)(3) 358 6639
Tait Electronics                        Fax   : (64)(3) 359 4632
PO Box 1645 Christchurch                Email : john.carter@tait.co.nz
New Zealand

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From this principle, all of life and physics may be deduced.