From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2010-02-16T01:47:18+09:00
Subject: Re: Parallel assignments vs. Serial assigments

On Mon, Feb 15, 2010 at 5:30 PM, Gavin
<thinkersplayground@googlemail.com> wrote:
> (My results show that parallel assignment is slower in this test)
>
> On Feb 15, 4:23 pm, Gavin <thinkersplaygro...@googlemail.com> wrote:
>> Hey all
>>
>> I was always under the impression that parallel assignments in Ruby
>> were faster than assigning variables individually.
>>
>> Recently I was curious to see how much faster it was and decided to
>> test it:
>>
>> class One
>>
>>   def initialize(first_name, last_name)
>>     @first_name = first_name
>>     @last_name  = last_name
>>   end
>>
>> end
>>
>> class Two
>>
>>   def initialize(first_name, last_name)
>>     @first_name, @last_name = first_name, last_name
>>   end
>>
>> end
>> require "rubygems"
>> require "benchmark"
>>
>> Benchmark.bmbm do |test|
>>   test.report("serial") do
>>     10000.times { |n| var =  One.new("gavin#{n}", "morrice")}
>>   end
>>   test.report("parallel") do
>>     10000.times { |n| var =  Two.new("gavin#{n}", "morrice")}
>>   end
>> end
>>
>> The results I get show that it's slower (in both Ruby 1.8.7 and Ruby
>> 1.9.1)
>>
>> Can anyone elaborate?

I think it might be because the parallel assigment creates an array
under the hood?

class One

 def initialize(first_name, last_name)
   @first_name = first_name
   @last_name  = last_name
 end

end

class Two

 def initialize(first_name, last_name)
   @first_name, @last_name = first_name, last_name
 end
end

class Three

 def initialize(*args)
   @first_name, @last_name = *args
 end
end


require "rubygems"
require "benchmark"

GC.disable

puts "Arrays before serial: #{ObjectSpace.each_object(Array){}}"
10000.times { |n| var =  One.new("gavin#{n}", "morrice")}
puts "Arrays after serial: #{ObjectSpace.each_object(Array){}}"
10000.times { |n| var =  Two.new("gavin#{n}", "morrice")}
puts "Arrays after parallel: #{ObjectSpace.each_object(Array){}}"

$ ruby test_parallel_assignment.rb
Arrays before serial: 3589
Arrays after serial: 3589
Arrays after parallel: 13589

Jesus.