From: Jake McArthur <jake.mcarthur@...>
Date: 2006-07-28T01:41:12+09:00
Subject: Re: String#chop slow?  REALLY slow?

On Jul 27, 2006, at 11:12 AM, Mat Schaffer wrote:

> Basically I want to drop what will be a trailing "\n" from input.

String#chomp would probably be a better idea for this, but that's OT  
I suppose. Regardless, its performance is the same as chop, it seems.

Here are my modifications:


require 'benchmark'

class String
   def my_chop
     self[0..-2]
   end
end

n = 100_000
bigstring = "I am a big string " * 5_000

Benchmark.bmbm do |bench|
   bench.report("Indexing") {
     n.times do
       bigstring[0..-1]
     end
   }

   bench.report("Chop") {
     n.times do
       bigstring.chop
     end
   }

   bench.report("My Chop") {
     n.times do
       bigstring.my_chop
     end
   }
end


And here are my results:


Rehearsal --------------------------------------------
Indexing   0.310000   0.000000   0.310000 (  0.347943)
Chop      11.940000  30.330000  42.270000 ( 44.501066)
My Chop   12.620000  30.720000  43.340000 ( 46.339651)
---------------------------------- total: 85.920000sec

                user     system      total        real
Indexing   0.230000   0.000000   0.230000 (  0.258177)
Chop      11.980000  30.680000  42.660000 ( 44.966923)
My Chop   12.610000  30.860000  43.470000 ( 45.859064)


Let's see how String#chop is implemented...


static VALUE
rb_str_chop(str)
     VALUE str;
{
     str = rb_str_dup(str);
     rb_str_chop_bang(str);
     return str;
}


So it's in C... interesting....

- Jake McArthur