From: Robert Klemme <bob.news@...>
Date: 2004-09-05T01:55:14+09:00
Subject: Re: autochomp?


"gabriele renzi" <rff_rff@remove-yahoo.it> schrieb im Newsbeitrag
news:v8g_c.76052$1V3.1849500@twister2.libero.it...
> Robert Klemme ha scritto:
>
> >
> > That's really interesting.  Did you also test with a real world file (a
file
> > with longer lines presumably)?  Interestingly enough, changing the block
of
> > #inject does make it nearly as fast as readlines:
>
> did you (both) also considered that the undelying OS' caching strategy
> may have some effect on this results?

Good point.  Now:

require 'benchmark'
require 'stringio'

st = StringIO.new

100000.times { st << "foo " * rand(10) << "\n" }

Benchmark.bm(7) do |x|
   st.seek 0

   x.report("readlines:") do
      st.readlines.each {|l| l.chomp!}
   end

   st.seek 0

   x.report("inject:") do
      st.inject([]) {|ar,line| line.chomp!; ar << line}
   end

   st.seek 0

   x.report("inject2:") do
      st.inject([]) {|ar,line| ar << line.chomp!}
   end

   st.seek 0

   x.report("foreach:") do
      st.each{|line| (lines||=[]) << line.chomp!}
   end

   st.seek 0

   x.report("foreach2:") do
      lines = []
      st.each{|line| lines << line.chomp!}
   end
end

Yields on my machine:

$ ruby filetest2.rb
             user     system      total        real
readlines:  0.031000   0.000000   0.031000 (  0.032000)
inject:  0.078000   0.000000   0.078000 (  0.077000)
inject2:  0.063000   0.000000   0.063000 (  0.051000)
foreach:  0.062000   0.000000   0.062000 (  0.073000)
foreach2:  0.094000   0.000000   0.094000 (  0.088000)

$ ruby filetest2.rb
             user     system      total        real
readlines:  0.031000   0.000000   0.031000 (  0.032000)
inject:  0.078000   0.000000   0.078000 (  0.079000)
inject2:  0.047000   0.000000   0.047000 (  0.051000)
foreach:  0.078000   0.000000   0.078000 (  0.074000)
foreach2:  0.078000   0.000000   0.078000 (  0.084000)

$ ruby filetest2.rb
             user     system      total        real
readlines:  0.281000   0.016000   0.297000 (  0.303000)
inject:  0.844000   0.015000   0.859000 (  0.855000)
inject2:  1.094000   0.000000   1.094000 (  1.174000)
foreach:  0.906000   0.000000   0.906000 (  0.905000)
foreach2:  0.375000   0.000000   0.375000 (  0.393000)

$ ruby filetest2.rb
             user     system      total        real
readlines:  0.344000   0.032000   0.376000 (  0.417000)
inject:  0.875000   0.000000   0.875000 (  0.974000)
inject2:  0.891000   0.031000   0.922000 (  0.943000)
foreach:  0.906000   0.016000   0.922000 (  0.915000)
foreach2:  0.391000   0.000000   0.391000 (  0.387000)

$ ruby filetest2.rb
             user     system      total        real
readlines:  0.312000   0.000000   0.312000 (  0.304000)
inject:  0.860000   0.000000   0.860000 (  0.858000)
inject2:  0.921000   0.015000   0.936000 (  0.943000)
foreach:  0.922000   0.000000   0.922000 (  0.916000)
foreach2:  0.391000   0.000000   0.391000 (  0.384000)

Hm...

    robert