C# out of memory exception in GetThumbnailImage on a server

问题

I am running the below code to create a thumbnail when a user sends us an image:

public int AddThumbnail(byte[] originalImage, File parentFile)
    {
        File tnFile = null;
        try
        {
            System.Drawing.Image image;
            using (System.IO.MemoryStream memoryStream = new System.IO.MemoryStream(originalImage))
            {
                image = System.Drawing.Image.FromStream(memoryStream);
            }
            Log.Write("Original image width of [" + image.Width.ToString() + "] and height of [" + image.Height.ToString() + "]");
            //dimensions need to be changeable
            double factor = (double)m_thumbnailWidth / (double)image.Width;

            int thHeight = (int)(image.Height * factor);
            byte[] tnData = null;
            Log.Write("Thumbnail width of [" + m_thumbnailWidth.ToString() + "] and height of [" + thHeight + "]");
            using (System.Drawing.Image thumbnail = image.GetThumbnailImage(m_thumbnailWidth, thHeight, () => false, IntPtr.Zero))
            {                    
                using (System.IO.MemoryStream tnStream = new System.IO.MemoryStream())
                {
                    thumbnail.Save(tnStream, System.Drawing.Imaging.ImageFormat.Jpeg);
                    tnData = new byte[tnStream.Length];
                    tnStream.Position = 0;
                    tnStream.Read(tnData, 0, (int)tnStream.Length);
                }
            }
//there is other code here that is not relevant to the problem

        }
        catch (Exception ex)
        {
            Log.Error(ex);
        }

        return (tnFile == null ? -1 : tnFile.Id);
    }

This works fine on my machine, but when I run it on a test server I always get an out of memory exception on the line: using (System.Drawing.Image thumbnail = image.GetThumbnailImage(m_thumbnailWidth, thHeight, () => false, IntPtr.Zero)) It is not manipulating a large image: it is trying to convert a 480*640 image into a 96*128 thumbnail. I don't know how to investigate / resolve this issue. Has anyone got any suggestions? It always happens, even after I have restarted IIS. I did initially think that the image might be corrupt but the dimensions are correct. Thanks.

回答1:

We also had similar problems using GDI+ Operations in our ASP.Net server. Your mention of your code running on a server made me think, that this could be the same problem.

Please be aware, that the usage of classes in the System.Drawing Namespace is not supported on a server. The fatal thing is, that it may work for some time and suddenly (even without code changes) errors occur.

We had to rewrite a significant part of our server code.

See the comment:

Caution note

Classes within the System.Drawing namespace are not supported for use within a Windows or ASP.NET service. Attempting to use these classes from within one of these application types may produce unexpected problems, such as diminished service performance and run-time exceptions. For a supported alternative, see Windows Imaging Components.

Source: http://msdn.microsoft.com/de-de/library/system.drawing(v=vs.110).aspx

回答2:

Many thanks @vcsjones for pointing me in the right direction. Instead of using image.GetThumbnailImage I call:

public static Image ResizeImage(Image imgToResize, Size size)
    {
        return (Image)(new Bitmap(imgToResize, size));
    }

The troublesome line of code is now:

using(Image thumbnail = ResizeImage(image, new Size(m_thumbnailWidth, thHeight)))

I got this line from Resize an Image C# It now works!

来源：https://stackoverflow.com/questions/27528057/c-sharp-out-of-memory-exception-in-getthumbnailimage-on-a-server

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image

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server