Hi Laurent,
This is great! I think I read in the discussion of StringScanner performance
about object allocation (though I didn't understand what exactly was happening
behind the scene), so I guessed it was about 'using block' with regular
expression match data.
For a word frequency count feature, I could use Test 2 script, but for other
part of the app, I needed match information ($`, $' to be exact), so this
performance improvement means a lot to my app.
Is this going to be in 0.8? Then, I'll test this with my app.
By the way, the regular expression itself seems to have a bug (not related to
this, but to negative look-ahead) and I issued(?) a ticket (though I'm not sure
I did it properly).
Best,
Yasu
On 2010/12/02, at 8:50, Laurent Sansonetti wrote:
> I spoke too fast, having a second look I found that it was possible to make
> the Match strings point to a unique object. I committed this optimization in
> r4964 and verified that no regression is introduced.
>
> Before:
>
> $ time /usr/local/bin/macruby -e "text=File.read('/tmp/foo.txt');
> freq=Hash.new(0); text.scan(/\w+/) {}"
>
> real 0m2.430s
> user 0m1.628s
> sys 0m1.030s
>
> After :)
>
> $ time ./miniruby -e "text=File.read('/tmp/foo.txt'); freq=Hash.new(0);
> text.scan(/\w+/) {}"
>
> real 0m0.121s
> user 0m0.100s
> sys 0m0.015s
>
> Laurent
>
> On Dec 1, 2010, at 2:46 PM, Laurent Sansonetti wrote:
>
>> Hi Yasu,
>>
>> I ran your tests in Shark. Tests 1 and 3 are significantly slower because
>> #scan and #gsub are called with a block, which means MacRuby has to create a
>> new Match object for every yield, to conform to the Ruby specs. Each Match
>> object contains a copy of the original string.
>>
>> MacRuby has a slow memory allocator (much slower than the original Ruby), so
>> one must be careful to not allocate too many objects. This is something we
>> are working on, unfortunately MacRuby doesn't fully control the object
>> allocator, as it resides in the libauto library (the Objective-C garbage
>> collector).
>>
>> In your case, I recommend using the method in Test 2, which is to not pass a
>> block.
>>
>> It is possible that we can reduce memory usage when doing regexps in
>> MacRuby, however after having a quick look at the source code I am not sure
>> something can be done for 0.8 :(
>>
>> Laurent
>>
>> On Dec 1, 2010, at 9:46 AM, Yasu Imao wrote:
>>
>>> Hello,
>>>
>>> I'm rewriting an app for text analysis in MacRuby, which I originally wrote
>>> in RubyCocoa. But I encountered a serious performance issue in MacRuby,
>>> which is related to processing text using regular expressions.
>>>
>>> I'm wondering if this will be taken care of in the near future (or already
>>> done in 0.8?).
>>>
>>> Below are my simple tests. The first two are essentially the same with a
>>> slightly different approach. Both are simply counting frequency of each
>>> word. I want to use the first approach not to count word frequencies, but
>>> in other processes. The third one is to test the speed of String#gsub with
>>> regular expression. I felt String#gsub was slow in my app, so I just
>>> wanted to test how slow it is compared to RubyCocoa.
>>>
>>>
>>> Test 1 - scan-block
>>>
>>> freq = Hash.new(0)
>>> text.scan(/\w+/) do |word|
>>> freq[word] += 1
>>> end
>>>
>>>
>>> Test 2 - scan array.each
>>>
>>> freq = Hash.new(0)
>>> text.scan(/\w+/).each do |word|
>>> freq[word] += 1
>>> end
>>>
>>>
>>> Test 3 - gsub upcase
>>>
>>> text.gsub!(/\w+/){|x| x.upcase}
>>>
>>>
>>> The results are in seconds. The original text is in English with 8154
>>> words. Each process was repeated 10 times to calculate processing times.
>>> Each test were done 3 times.
>>>
>>> Ruby 1.8.7 Test1 - scan-block: 0.542, 0.502,
>>> 0.518
>>> Ruby 1.8.7 Test2 - scan array.each: 0.399, 0.392,
>>> 0.399
>>> Ruby 1.8.7 Test3 - gsub upcase: 0.384, 0.349, 0.390
>>>
>>> MacRuby 0.7.1 Test1 - scan-block: 27.612, 27.707, 27.453
>>> MacRuby 0.7.1 Test2 - scan array.each: 3.556, 3.616, 3.554
>>> MacRuby 0.7.1 Test3 - gsub upcase: 27.613, 26.826, 27.327
>>>
>>>
>>> Thanks,
>>> Yasu
>>> _______________________________________________
>>> MacRuby-devel mailing list
>>> [email protected]
>>> http://lists.macosforge.org/mailman/listinfo.cgi/macruby-devel
>>
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