Attempted to read or write protected memory. exception in Websupergoo ABCPDF7 on dispose

Question

I get randomly (on the live environment its like once every 2 weeks with a very active and hard working windows service, it resizes about 50000+ images per day) AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

The stacktrace is: Stack:

at WebSupergoo.ABCpdf7.Internal.NDoc._Clear(IntPtr inDoc)
at WebSupergoo.ABCpdf7.Internal.NDoc.Clear(IntPtr inDoc)
at WebSupergoo.ABCpdf7.Doc.Clear()
at WebSupergoo.ImageGlue7.Canvas.Dispose(Boolean disposing)
at WebSupergoo.ImageGlue7.Canvas.Dispose()
at XXXXX.Classes.Imaging.Image.Resize(Int32 width, Int32 height, Boolean addTransparent) in <path>\Image.cs:line 149
at XXXXX.Classes.XXXXX.Object.Import.Media.CreateImageScale(String destDir, Int32 width) in <path>\Media.cs:line 272
at XXXXX.Classes.XXXXX.Object.Import.Media.CreateResizedImages(String threadId) in <path>\Media.cs:line 242
at XXXXX.Classes.XXXXX.Object.Import.Threading.ResizeThread.Run(Object o) in <path>\ResizeThread.cs:line 38

Here is the code for the resize method:

    public void Resize(int width, int height, bool addTransparent)
    {

        using (Canvas tempCanvas = new Canvas())
        {
            DrawOptions options = new DrawOptions();
            if (height == 0)
            {
                if (width <= Width)
                {

                    options.Limit = new Size(width, 0);
                }
                else
                {
                    double scale = (double)width / (double)Width;

                    options.Transform.Magnify(scale, scale, 0, 0);

                }
            }
            else if (width == 0)
            {

                if (height <= Height)
                {
                    options.Limit = new Size(0, height);
                }
                else
                {
                    double scale = (double)height / (double)Height;

                    options.Transform.Magnify(scale, scale, 0, 0);
                }
            }
            else
            {
                double scaleX = (double)width / (double)Width;
                double scaleY = (double)height / (double)Height;

                options.Transform.Magnify(scaleX, scaleY, 0, 0);
            }

            //add transparency if set.
            if (addTransparent)
                options.Transparency = true;

            tempCanvas.DrawImage(CurrentImage, options);

            CurrentImage = tempCanvas.ToImage();
        } <<<<---- HERE WE GET THE EXCEPTION ON THE DISPOSE
    }

Can anyone help me solve why i get this error or if there is anything I can do about it.

score 0 · Answer 1 · answered Aug 23 '11 at 11:16

0

Do you perform any non-thread safe operation? It's hard to say from here but the GC may destroy prematurely something that another thread tries to use - that could result in random-looking behaviour. You could transform the whole thing into static methods or use mutexes or other syncronization methods.

Another things I noticed: What is width and height, Width and Height? I don't see why you should care about zero width image more than dropping an exception. I never used NDoc, but it seems strange too that you have it on the stack in production code.

answered Aug 23 '11 at 11:16

WebMonster

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I don't use NDoc Directly Its the Canvas that uses them. Also i have been carefull about the threading. I don't think that is the problem.. But I will doublecheck that to see if there is anything shared that could be the problem. Just that its strange that it doesnt happen more if thats the problem.. I can have up to 1000 threads queued up in the threadpool and such should be more conflicts than just sometimes rarly. – JohanSellberg Aug 23 '11 at 11:39

Attempted to read or write protected memory. exception in Websupergoo ABCPDF7 on dispose

1 Answers1