From: bwv549 <jtprince@...>
Date: 2007-04-03T23:05:07+09:00
Subject: Re: implementing an array based class

Thanks for the pointers.  I'd love to know how to do proper memory
benchmarking.  It does not seem trivial, I guess.

Regarding object initialization, I guess I'm really interested in
total time to initialize the object and fill in all attributes with
values (as this is what I'm going to be facing before I can use any of
the objects).  I've incorporated this aspect into a similar benchmark
for comparison:

Rehearsal --------------------------------------------------
Class1           5.666667   0.533333   6.200000 (  3.730552)
Class2           5.983333   0.516667   6.500000 (  3.904695)
Struct           3.950000   0.250000   4.200000 (  2.518688)
ArrayBased       2.033333   0.350000   2.383333 (  1.431213)
Array.new        2.100000   0.316667   2.416667 (  1.443011)
Array []         0.833333   0.266667   1.100000 (  0.671233)
---------------------------------------- total: 22.800000sec

                     user     system      total        real
Class1           5.550000   0.600000   6.150000 (  3.686555)
Class2           5.716667   0.666667   6.383333 (  3.834078)
Struct           3.883333   0.316667   4.200000 (  2.527558)
ArrayBased       2.166667   0.266667   2.433333 (  1.445458)
Array.new        2.150000   0.300000   2.450000 (  1.474190)
Array []         0.900000   0.233333   1.133333 (  0.684567)

----------------------------------------------------

#!/usr/bin/ruby

require 'benchmark'
include Benchmark

attribute_array = (1...7).to_a

class Class1
  def initialize(attribute_array)
    (@f1, @f2, @f3, @f4, @f5, @f6, @f7) = attribute_array
  end
end

class Class2
  def initialize(f1=nil, f2=nil, f3=nil, f4=nil, f5=nil, f6=nil,
f7=nil)
     @f1=f1
     @f2=f2
     @f3=f3
     @f4=f4
     @f5=f5
     @f6=f6
     @f7=f7
  end
end


StructClass = Struct.new(:f1, :f2, :f3, :f4, :f5, :f6, :f7)
filled_in = StructClass.new( *attribute_array )

class ArrayBased < Array
end

filled_in = ArrayBased.new(attribute_array)


REP = 1_000_000

bmbm(15) do |re|
  re.report("Class1") { REP.times { Class1.new(attribute_array) } }
  re.report("Class2") { REP.times { Class2.new(*attribute_array) } }
  re.report("Struct") { REP.times
{ StructClass.new(*attribute_array) } }
  re.report("ArrayBased") { REP.times
{ ArrayBased.new(attribute_array) } }
  re.report("Array.new") { REP.times { Array.new(attribute_array) } }
  re.report("Array []") { REP.times { [*attribute_array] } }
end

----------------------------------------------------

For speed, at least, my initialize observations appear to hold (in
this benchmark, anyway).
Ordered by fastest filled object creation: Array [], ArrayBased &
Array.new, Struct, Class

Kind regards,
john