How to prevent Third Party DLL's StackOverflow Exception from killing Main Application?

user_1662679 0
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We are creating a PDF Preview using PDFToImage DLL of PQScan.We need to create preview image of the first page of PDF.

Whenever I try to get the image, it throws System.StackOverflowException. Which can't be catched in try-catch block and it causes the crash for the application.

try
{
    using (PQScan.PDFToImage.PDFDocument doc = new PQScan.PDFToImage.PDFDocument())
    {
        doc.LoadPDF(UTFPDFPath);
        doc.DPI = 150;
        var temp = doc.PageCount;
    

        using (Bitmap bmp = doc.ToImage(0)) //System.StackOverflowException here
        {
            bmp.Save(BigPrevName, ImageFormat.Gif);
        }
    }
}
catch (Exception ex)
{
}

- $exception {"Exception of type 'System.StackOverflowException' was thrown."} System.StackOverflowException

c#
2 Answers

The short answer here is "no"; a stack-overflow scenario cannot be reliably caught / recovered from.

  • make sure you're on the most recent version available (it might be fixed!)
  • see whether the documentation lists this as a known issue with possible workaround
  • if it is a paid product, ask them to fix it as part of your support
  • if it is open source, consider fixing it yourself and contributing the fix

If none of these are possible, then the fallback would be to write a second executable that just does this processing (using either IPC or file-based means to get data to/from the second process) - then spawn that second process in the knowledge that if it explodes, only the child process has been burned.

Marc_Gravell_233540

As MSDN says using is not designed to catch exceptions because it is actually convenient way to do 'try-finally'. You should change it for something like this:

Bitmap bmp;
try
{
    bmp = doc.ToImage(0);
    bmp.Save(BigPrevName, ImageFormat.Gif);
}
catch (Exception ex)
{
    //process exception
}
finally
{
    if (bmp != null)
      bmp.Dispose();
}
user_54002580
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