Re: C++ Speed Vs. Java

{ Note to moderators: In the first attempt to make this post I omitted
GC collected version to keep the post small as the difference in code
is minimal. }

Keith H Duggar wrote:


BTW, induced by the recent thread about GC, I have been experimenting a
little bit comparing memory consumption too.

I was using this simple benchmark code:

class A {
        A *a;
        A *b;
public:
        A(int n) { if(n) { a = new A(n - 1); b = new A(n - 1); } else a = b =
NULL; }
        ~A() { delete a;delete b; }
};

int main()
{
        A *a[256];
        for(int i = 0; i < 256; i++)
                a[i] = new A(10);
        for (int i = 0; i < 10000; ++i) {
                delete a[i & 255];
                a[i & 255] = new A(10);
        }
        for(int i = 0; i < 256; i++)
                delete a[i];
}

and compared to this C# version:

using System;
using System.Collections.Generic;
using System.Text;

namespace ConsoleApplication1
{

class A {
  private A a;
  private A b;
  public A(int n) { if(n > 0) { a = new A(n - 1); b = new A(n - 1); }
  }
}

class Program {
    static void Main(string[] args)
    {
            A[] a = new A[256];
            for(int i = 0; i < 256; i++)
                    a[i] = new A(10);
            for (int i = 0; i < 10000; ++i) {
                    a[i & 255] = new A(10);
            }
    }
}

}

C# run 3 times slower than C++ version (using our current allocator),
but used 30x more memory! (150MB vs 5MB)

Really excellent way how to avoid memory problems....

--
Mirek Fidler
U++ team leader. http://www.ultimatepp.org

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