How to catch 'FatalExecutionEngineError' in C#?

Question

I am experimenting a tedious problem with a C# routine that I cannot to solve. I am developing an application that opens a ESRI ShapeFile using the GDAL library (an DLL library written in C++ to manipulate geographical data) and shows the map in a PictureBox component. When I use a vector of System.Drawing.Point objects to draw the polygons I get the following message:

Managed Debugging Assistant 'FatalExecutionEngineError' has detected a problem in 'C:\Users\polli\ipeageo-git\IpeaGEO\bin\Debug\IpeaGEO.vshost.exe'. Additional information: The runtime found a fatal error. The error address is 0x6ced9a0f, in thread 0x1618. The error code is 0xc0000005.

This is the code that throws the exception:

private void drawGeometry(Geometry geo, Graphics g, bool fill)
{
    // Some code here...
    // ...

    // Get the points count and the array to ask GDAL for coordinates.
    int count = geo.GetPointCount();
    double[] v = new double[2];
    Point[] polygon = new Point[count];

    for (int pid = 0; pid < count; pid++)
    {
        geo.GetPoint(pid, v);    // This is a call to GDAL (unmanaged) code.
        polygon[pid].X = getX((float)v[0]);
        polygon[pid].Y = getY((float)v[1]);

        // The Exception occurs just HERE!
        g.DrawPolygon(fgPen, polygon); // <--- EXCEPTION!!!
        if (fill) g.FillPolygon(fillBrush, polygon);
    }

    // Some code here...
    // ...
}

I have another version of this function that works fine, where I am drawing each line segment without allocating memory:

private void drawGeometry(Geometry geo, Graphics g, bool fill)
{
    // Some code here...
    // ...

    Point start = new Point(), current = new Point(), previous = new Point();

    // Get the points count and the array to ask GDAL for coordinates.
    int count = geo.GetPointCount();
    double[] v = new double[2];

    for (int pid = 0; pid < count; pid++)
    {
        geo.GetPoint(pid, v);    // This is a call to GDAL (unmanaged) code.
        if (pid == 0)
        {
            start.X = previous.X = getX((float)v[0]);
            start.Y = previous.Y = getY((float)v[1]);
         } // if
         else
         {
             previous.X = current.X;
             previous.Y = current.Y;
         } // else

         current.X = getX((float)v[0]); current.Y = getY((float)v[1]);
         g.DrawLine(fgPen, previous.X, previous.Y, current.X, current.Y);
    } // for
    g.DrawLine(fgPen, start.X, start.Y, current.X, current.Y);

    // Some code here...
    // ...
}

I need to fill some polygons and I cannot to do it with the second version of the code (that is working fine). The use of try ... catch does not capture the exception.

I think the problem occurs when the garbage collector is running in the background and I try to access the polygon variable (that is a vector of about 2000 elements... and this code is inside a for statement).

Anybody knows how to catch (or, even better, avoid) this kind of exception?

Answer 1

FatalExecutionEngineError are not catchable in exception handling, they are usually system bugs or marshal errors, both can't be handled in .NET app.