From: Caio Chassot <lists@...2studio.com>
Date: 2006-07-28T01:40:17+09:00
Subject: Re: String#chop slow?  REALLY slow?


On 2006-07-27, at 13:36 , Caio Chassot wrote:

>> Basically I want to drop what will be a trailing "\n" from input.   
>> But it appears that using String#[] and if statements is nearly  
>> 200 times more efficient than chop.   Which just seems really  
>> weird, so here's the benchmark.  Maybe I'm doing something wrong.
>
> Well, if you implement chop fully, you get very similar results:

Ah, but rangeless indexing yields much much better results:

RubyMate r4106 running Ruby v1.8.4 (/usr/local/bin/ruby)
 >>> untitled

Rehearsal -------------------------------------------------
Indexing        0.110000   0.000000   0.110000 (  0.151018)
Chop            3.430000   7.920000  11.350000 ( 15.030196)
Indexing crlf   0.110000   0.000000   0.110000 (  0.128584)
Chop crlf       3.430000   7.920000  11.350000 ( 14.815128)
--------------------------------------- total: 22.920000sec

                     user     system      total        real
Indexing        0.110000   0.000000   0.110000 (  0.134087)
Chop            3.430000   7.980000  11.410000 ( 14.305555)
Indexing crlf   0.110000   0.000000   0.110000 (  0.125122)
Chop crlf       3.420000   7.990000  11.410000 ( 13.869411)

---

require 'benchmark'

n = 20_000
bigstring = "I am a big string " * 5_000

Benchmark.bmbm do |bench|
   bench.report("Indexing") {
     n.times do
       bigstring[-2,2] == "\r\n" ? bigstring[-2,2] : bigstring[-1,1]
     end
   }

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

   bigstring << "\r\n"

   bench.report("Indexing crlf") {
     n.times do
       bigstring[-2,2] == "\r\n" ? bigstring[-2,2] : bigstring[-1,1]
     end
   }

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