BarcodeReader clearly not thread safe

Aspose.BarCode Product Family
1

I am creating an instance of the BarcodeReader class on 50 different threads, each thread receiving a different System.Drawing.Bitmap. Essentially, there are 50 instances of BarcodeReader, with 50 different images, all calling Read() at the same time.


Sometimes a barcode is detected in an image which SIMPLY DOES NOT HAVE A BAR CODE.

Sometimes odd exceptions come from BarcodeReader.Read(). ArgumentOutOfRangeExceptions and stuff.

Here is the function which is being invoked on 50 threads, with 50 different inputs, at the same time:

        IEnumerable ReadBarcodesAspose(PageImage pageImage, RecognitionHints.Orientation orientation)

{

var read = new List();

var loop = 0;

        // try until success or maximum attempt reached
        while (loop != -1 && loop < 4)
        {
            try
            {
                using (var b = new Bitmap(pageImage.Image))
                using (var r = new BarCodeReader(b, BarCodeReadType.Code39Standard))
                {
                    r.OrientationHints = orientation;
                    while (r.Read())
                        read.Add(r.GetCodeText());
                }

                loop = -1;
            }
            catch (Exception e)
            {
                loop++;
            }
        }

        if (read.Count > 0 && pageImage.Index % 2 != 0)
            Debugger.Break();

        return read;
    }</string></string></pre></div><div><br></div><div>Currently, only PageItem instances with an even Index value actually have a barcode, so I've got it breaking the debugger when it finds a barcode on a non-even page. While the debugger is broken on this line, I am running this in the immediate window:<br><br>pageImage.Image.Save(@"C:\Users\jhaltom\foo.png", ImageFormat.Png");<br><br>When I open the resulting Png, as expected, there is no barcode. However, it's read a bar code (read.Count > 0). In fact, the barcode that is returned IS on another page. A completely different page. From a completely different Image instance, which was handed to a completely different thread.</div><div><br></div><div>I want to repeat, I explicitly save the pageImage.Image variable while broken in this method, and it does not have any barcode on it, and yet, in this method, GetCodeText() has managed to return a barcode value.<br><br>When I set my code down to a single thread, this works fine.</div><div><br></div><div>I am running version 5.1.0 delivered by NuGet. It's in evaluation mode, and parsing only for Code39Standards. I'm evaluating your code to determine if I want to purchase it. Not being truly thread safe kind of hurts that. :)</div>
2

I should note, the odd exception handling I’ve included is probably not required: I was attempting to work around the random exceptions being thrown from BarcodeReader.Read(), in hopes of getting the solution working. However, I suspect those Exceptions are being thrown for the same thread-safety reason causing my main issue.

3

Hi Jerome,


Please accept our apologies for the delay. We are working over your query and will get back to you as soon as possible.

4

Hi Jerome,


Thank you for your interest in our Aspose products. First off, You can avoid evaluation limitations by getting a temporary license for 30 days and try the latest version at your end.

You can learn all about how Aspose products are licensed by checking out the Licenses FAQ here: http://www.aspose.com/corporate/purchase/faqs/default.aspx
http://www.aspose.com/docs/display/barcodenet/Licensing

The extended Code 39 is a modification of the NORMAL (standard) version that can encode the complete 128 ASCII character set. If code39standard does not read then you can use code39extended symbology to recognize a barcode. Code 39 Standard/Extended always go near each other. So it is good to always check for Standard and Extended together during recognition. Please modify code line as:

using (var r = new BarCodeReader(str, BarCodeReadType.Code39Standard | BarCodeReadType.Code39Extended))

While using latest versions of Aspose.BarCode v5.2 & v5.1, I’m unable to reproduce the issues as you mentioned. I’ve prepared a console application for you, please give it a try with input images and share results here in this thread. We’ll take a closer look and guide you accordingly.