内存不足，使用进程

Question

Ok, so I know I should be using the ImageMagick DLL... and I'm learning, testing, and working up to doing that. But in the mean time I'm using the inefficient method of calling Imagemagick's convert.exe via a process.

It works fine with hundreds of images when I'm testing. But then I move my WindowsForms program to a faster machine and it crashes every time at the same point.

It's a two step Process call. The first time loop through all the files and produce the PNGs. Then I loop through all the PNGs and composite it with a background and output a JPG. But EVERY time at exactly 22 images it errors "System.OutOfMemoryException: Out of memory." Is there something that is filling up that I need to kill or something?

    foreach (string file in files)
            {
                try
                {
                    string captureImg = Path.GetFileName(file);
                    string maskImg = file.Replace("X.JPG", "Y.JPG");
                    string OutputImage = string.Format("{0}.png", Path.GetFileNameWithoutExtension(captureImg));
                    string output = Path.Combine(destFolder, OutputImage);
                    //MessageBox.Show(output);
                    progressBarImage.Value = progressBarImage.Value + 1;
                    lblStatus.Text = string.Format("Image {0} of {1}", progressBarImage.Value, maxFiles);
                    makePNG(file, maskImg, output);
                    Application.DoEvents();

                }
                catch (Exception)
                {
                }
            }

            if (chkBG.Checked)
            {
                //try
                //{
                    string JPGdir = Path.Combine(destFolder, "JPGs");
                    string[] PNGfiles = Directory.GetFiles(destFolder, "*C.PNG");

                    lblProgress.Text = "Generating JPGs with Background";
                    progressBarImage.Value = 0;
                    progressBarImage.Maximum = files.Length;
                    message = "PNG and JPG Export Complete";
                    if (!Directory.Exists(JPGdir))
                    {
                        Directory.CreateDirectory(JPGdir);
                    }
                    foreach (string PNGfile in PNGfiles)
                    {
                        Application.DoEvents();
                        string outputJPG = string.Format("{0}.jpg", Path.GetFileNameWithoutExtension(PNGfile));
                        string result = Path.Combine(JPGdir, outputJPG);
                        progressBarImage.Value += 1;
                        lblStatus.Text = string.Format("Image {0} of {1}", progressBarImage.Value, files.Length);
                        makeJPG(PNGfile, txtBackground.Text, result);
                        //MessageBox.Show(PNGfile);

                    }

private void makePNG(string source, string mask, string output)
        {
            if (!source.EndsWith("Y.JPG"))
            {
                Process proc = new Process();
                string appPath = Path.GetDirectoryName(Application.ExecutablePath);
                proc.EnableRaisingEvents = false;
                proc.StartInfo.FileName = @"""C:\Program Files\ImageMagick-6.9.0-Q16\convert.exe""";
                proc.StartInfo.Arguments = string.Format(@"{0} {1} -alpha off -compose  copy-opacity -level 5%  -composite {2}", source, mask, output);
                proc.StartInfo.UseShellExecute = false;
                proc.StartInfo.RedirectStandardOutput = true;
                proc.StartInfo.CreateNoWindow = true;
                proc.Start();
                proc.WaitForExit();

            }
        }

        private void makeJPG(string source, string background, string output)
        {
            float BGimg = Image.FromFile(background).Height;
            float SubjectImg = Image.FromFile(source).Height;
            float ResultHeight = 100 * (BGimg / SubjectImg);
            int Height = Convert.ToInt32(ResultHeight);


            Process procJPG = new Process();
            string appPath = Path.GetDirectoryName(Application.ExecutablePath);
            procJPG.EnableRaisingEvents = false;
            procJPG.StartInfo.FileName = @"""C:\Program Files\ImageMagick-6.9.0-Q16\convert.exe""";
            procJPG.StartInfo.Arguments = string.Format(@"{1} ( {0} -resize {3}% ) -gravity South -composite {2}", source, background, output, Height);
            procJPG.StartInfo.UseShellExecute = false;
            procJPG.StartInfo.RedirectStandardOutput = true;
            procJPG.StartInfo.CreateNoWindow = true;
            procJPG.Start();
            procJPG.WaitForExit();
        }

Answer 1

At first glance, you are using Image.FromFile twice in makeJPG() and not disposing the objects. Image.FromFile will usually create unmanaged GDI+ handles that need to be disposed.

From the documentation :

The file remains locked until the Image is disposed.

So at first glance I'd assume you are just loading too much images in memory, and I'd try:

private void makeJPG(string source, string background, string output)
{
  using(var backgroundImg = Image.FromFile(background))
  using(var sourceImg = Image.FromFile(source))
  {
    float BGimg = backgroundImg.Height;
    float SubjectImg = sourceImg.Height;
    float ResultHeight = 100 * (BGimg / SubjectImg);
    int Height = Convert.ToInt32(ResultHeight);


    Process procJPG = new Process();
    string appPath = Path.GetDirectoryName(Application.ExecutablePath);
    procJPG.EnableRaisingEvents = false;
    procJPG.StartInfo.FileName = @"""C:\Program Files\ImageMagick-6.9.0-Q16\convert.exe""";
    procJPG.StartInfo.Arguments = string.Format(@"{1} ( {0} -resize {3}% ) -gravity South -composite {2}", source, background, output, Height);
    procJPG.StartInfo.UseShellExecute = false;
    procJPG.StartInfo.RedirectStandardOutput = true;
    procJPG.StartInfo.CreateNoWindow = true;
    procJPG.Start();
    procJPG.WaitForExit();
  }
}

Since you are actually not using the images (just getting their height), you could make those using blocks smaller, but I'll leave that to you.

... but ...

About the OutOfMemoryException

Also, you say it happens EXACTLY at 22 images (which would be weird for getting out of memory, unless the images are consistently big), but reading the same documentation:

If the file does not have a valid image format or if GDI+ does not support the pixel format of the file, this method throws an OutOfMemoryException exception.

So make sure the 22nd image (either the "source" or the "background", depending on where it throws) has a correct format