Batch Image Manipulation keeps hanging

Question

I use the following code to scale and crop all images in a folder.

string fileNameWithoutExtension = Path.GetFileNameWithoutExtension(file);
string fileExtension = Path.GetExtension(file);
string filePath = Path.GetDirectoryName(file);
string newFileName = string.Empty;
long fileSize = new FileInfo(file).Length;

if (fileSize > fileSizeLimit)
{
    string tempFile = System.IO.Path.GetTempFileName();
    File.Copy(file, tempFile, true);
    Bitmap sourceImage = (Bitmap)System.Drawing.Image.FromFile(tempFile);

    System.Drawing.Image imgPhoto = ScaleCrop(sourceImage, sourceImage.Width / 4, sourceImage.Height / 4, AnchorPosition.Top);
    Bitmap bitImage = new Bitmap(imgPhoto);
    File.Delete(file);

    newFileName = filePath + "\\" + fileNameWithoutExtension + "_" + DateTime.Now.ToString("yyyyMMddHHmmss") + "_" + CoilWarehouseProcessed + fileExtension;

    bitImage.Save(newFileName, System.Drawing.Imaging.ImageFormat.Jpeg);

    imgPhoto.Dispose();
    bitImage.Dispose();
}

If I run the application locally (in debug mode in VS2010) and point it to a network drive then all images are processed every time.

If I run it from a our local webserver the problem is that the app may process no images, it may process 5, it may process 1, it never does all of the images in a given folder, only ever some of them... then it hangs in the clients browser.

There are no events to view via the event log... the application does not crash or error in anyway... the fact that it will process an image proves it's not a permissions issue.

Any ideas why this is happening?

EDIT: Thanks to wazdev, but I ended up testing a less intrusive (and also don't like dependencies relying on 3rd party software) solution, and it all seems good so far... Basically I changed it so that when it copies the stream to produce a new image 'System.Drawing.Image imgPhoto = ...' to use a using statement to ensure that the 'temp' image is disposed of. I also moved the delete of the original (uncropped / unscaled image) file to be the last operation (In tests it has worked fine, only time will tell once more users come online and concurrency is tested):

string tempFile = System.IO.Path.GetTempFileName();
File.Copy(file, tempFile, true);
Bitmap sourceImage = (Bitmap)System.Drawing.Image.FromFile(tempFile);

System.Drawing.Image imgPhoto = ScaleCrop(sourceImage, sourceImage.Width / 4, sourceImage.Height / 4, AnchorPosition.Top);

Bitmap bitImage;

using (var bmpTemp = new Bitmap(imgPhoto))
{
    bitImage = new Bitmap(bmpTemp);
}

newFileName = filePath + "\\" + fileNameWithoutExtension + "_" + DateTime.Now.ToString("yyyyMMddHHmmss") + "_" + CoilWarehouseProcessed + fileExtension;

bitImage.Save(newFileName, System.Drawing.Imaging.ImageFormat.Jpeg);

imgPhoto.Dispose();
bitImage.Dispose();
File.Delete(file);

EDIT2: It's been live now for a few days and i've tested it every day and it is working well.. Here's all that I did;

Basically inside the ScaleCrop() call there was a GC.Collect and a Wait For Pending Finalisers() call. I removed the wait for pending call and moved the GC.Collect() to after the File.Delete().

score 2 · Answer 1 · answered Mar 01 '16 at 10:18

2

I've seen this behaviour in the past when RAM was exhausted resulting in paging to disk. I've found a great deal of success in utilising the ImageResizing.net libraries: http://imageresizing.net/

I updated my code to use this library and have never looked back.

HTH

(I have no affiliation with imageresizing.net - I'm just a very happy user)

answered Mar 01 '16 at 10:18

wazdev

323
4
11

Thanks but... It seems as though you must expose the images to the internet to use imageresizer.net, i.e. accessible via a URL... it is a restful api that sizes on the fly... the images I work with are secure and sensitive and so cannot be made available on the internet, they are instead hidden away on a network drive. – Paul Zahra Mar 01 '16 at 11:25
Hi Paul- you can use their "Managed API": http://imageresizing.net/docs/v4/managed Here's the nuget package: https://www.nuget.org/packages/ImageResizer/ – wazdev Mar 01 '16 at 11:30
@PaulZahra Did you have any luck researching this further? – wazdev Mar 03 '16 at 02:46
yes and no... still testing over time, worked well yesterday, works well today (it would allways fail after being in use for a day so that a good sign)... It seems you were right in that it was a RAM issue... basically inside the ScaleCrop() call there was a GC.Collect... and a Wait For Pending Finalisers() call... removed wait for pending call and moved the GC.Collect() to after the File.Delete(). – Paul Zahra Mar 03 '16 at 08:52
Image manipulation is notoriously tricky. I use imageresizing.net to do server side work and have found it to be very reliable. – wazdev Mar 04 '16 at 01:01

Batch Image Manipulation keeps hanging

1 Answers1