Access violation to unmanaged memory from finalizer

Question

I tried to clean up memory of unmanaged classes from c++/cli finalizer and it gave me AcessViolation error. I do something like this:

MyClass::!MyClass()
{

    if(_unmanaged)
    {
    _unmanaged->Delete();
    _unmanaged = 0;
    }
}

Could anyone know, what the problem? Thanks for answers.

_unmanaged, in my case, vtk class, Delete - standart procedure to clean up vtk objects. It may be another method of unmanaged class in any case it will be AccessViolation. — Ivan_Deev, Apr 26 '12 at 07:25
And are you sure you've not either a) already deleted `_unmanaged` or b) never actually created it in the first place? — Nick, Apr 26 '12 at 07:36
Have you switched on unmanaged debugging and debugged into it? — Nick, Apr 26 '12 at 07:40
No, i not debugging unmanaged. I think, problem not in _unmanaged. It is look like closing unmanaged memory to use from clr in finalizing stage. — Ivan_Deev, Apr 26 '12 at 07:46
MyClass::~MyClass() { this->!MyClass(); } MyClass::!MyClass() { if(_unmanaged) { _unmanaged ->Delete(); _unmanaged = 0; } } — Ivan_Deev, Apr 26 '12 at 07:59
I can't see anything which would cause an access violation here. It has to be something else in your code. Sorry I can't be of more help... — Nick, Apr 26 '12 at 08:02
How are you initializing `_unmanaged`? Are you explicitly setting it to null in the constructor and initializing it later? Are you doing the real initialization in the constructor? — David Yaw, Apr 26 '12 at 15:56

score 0 · Answer 1 · answered Apr 26 '12 at 11:36

0

Ok, I have one guess.

Finalizer works from it's own thread, so when you try to dispose your object manually race conditions can occur.

I saw your comment about "already deleted object" but I would check it once again.

MyClass::~MyClass()
{
   this->!MyClass();

   GC::KeepAlive(this);
}

answered Apr 26 '12 at 11:36

Eugene

The finalizer works on its own thread, but if something has a reference to the object, which is required in order to call Dispose, then the garbage collector won't touch it. – David Yaw Apr 26 '12 at 15:53

1 Answers1