From: John Joyce <dangerwillrobinsondanger@...>
Date: 2007-09-29T02:21:31+09:00
Subject: Re: Ruby performance


On Sep 28, 2007, at 11:06 AM, khaines@enigo.com wrote:

> On Sat, 29 Sep 2007, Vasyl Smirnov wrote:
>
>> Hi,
>>
>> I'm new to Ruby, and I've just tried to measure it's performance
>> compared to Python, and got some interesting results.
>>
>> The Ruby test script is:
>>
>> #!/usr/bin/env ruby
>>
>> s = ""
>> i = 0
>> while line = gets
>>  s += line
>>  i += 1
>>  puts(i) if i % 1000 == 0
>> end
>>
>> and the Python one:
>>
>> #!/usr/bin/env python
>>
>> import sys
>>
>> s = ""
>> i = 0
>> for line in sys.stdin:
>>  s += line
>>  i += 1
>>  if i % 1000 == 0: print i
>>
>>
>> I fed a 1MB-large file as input to each of this script. The strange
>> thing is that the Ruby version starts to output progress slower and
>> slower as the s string grows. The Python version went smoothly.
>
> This is because "string" + "otherstring" allocates a new string,  
> "stringotherstring".
>
> Use << instead, and it will concatenate "otherstring" to the  
> orignal "string".
>
> s = ""
> i = 0
> while line = gets
>  s << line
>  i += 1
>  puts(i) if i % 1000 == 0
> end
>
> Performance should be a lot better with that version.
>
>
> Kirk Haines
>
>
That should be on a Ruby Optimization list somewhere!