Re: Garbage Collection - The Trash Begins To Pile Up

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Dave Harris wrote:


OK, as I said, you got me interested, so I tried to put it to test.

C# version:

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(4);
        for (int i = 0; i < 10000000; ++i) {
            a[i & 255] = new A(4);
        }
     }
}
}

C++ version:

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;
    }
};

CONSOLE_APP_MAIN
{
    A *a[256];
    for(int i = 0; i < 256; i++)
        a[i] = new A(4);
    for (int i = 0; i < 10000000; ++i) {
        delete a[i & 255];
        a[i & 255] = new A(4);
    }
    for(int i = 0; i < 256; i++)
        delete a[i];
}

(U++ heap allocator was used)

Results:

C#: real:10.671 user:10.265 sys: 0.062 page:10292 KB work:7284 KB
C++: real:10.625 user:10.562 sys: 0.015 page: 592 KB work:1536 KB

OK, this was the first (and hopefully the last) time I have ever used
C#, it is possible I have done something wrong.

If not, I officially proclaim GC speed & size assertions a *MYTH*.

(Especially *size* ;)

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

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