Trying to print using multiple instances of GhostScript with Parallel loop.

Question

I have a function that uses GhostScript.NET to print PDF documents. Everything works correctly if one user is trying to print, however when multiple users try to print simultaneously it doesn't print all of the documents. I recognize that I will have create multiple instances of ghostscript in order to achieve multiple-simultaneous printing. I came accross this question:

Ghostscript.NET Multithreading Issue

One of the users says to create a parallel forloop, but I'm honestly not sure how to structure one so that it creates the correct amount of instances of GhostScript.

I have the main function:

 public static void PrintFormPdfData(byte[] formPdfData, string printer)
    {
        var filename = @"C:\TEMP\report.pdf";
        using (var file = new FileStream(filename, FileMode.Create, FileAccess.ReadWrite))
        {
            file.Write(formPdfData, 0, formPdfData.Length);
            using (GhostscriptProcessor processor = new GhostscriptProcessor())
            {
                List<string> switches = new List<string>();
                switches.Add("-empty");
                switches.Add("-dPrinted=false");
                switches.Add("-dBATCH");
                switches.Add("-dPDFFitPage");
                switches.Add("-dNOPAUSE");
                switches.Add("-dNOSAFER");
                switches.Add("-dNumRenderingThreads=3");
                switches.Add("-dNumCopies=1");
                switches.Add("-sDEVICE=mswinpr2");
                switches.Add("-sOutputFile=%printer%" + printer);
                switches.Add(filename);
                try
                {
                    processor.StartProcessing(switches.ToArray(), null);
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex.Message);
                }
                finally
                {
                    File.Delete(filename);
                }
            }
        }
    }

Any help would be greatly appreciated.

The problem with your code is you're using the same file path for all the callers — VMAtm, Feb 15 '17 at 01:04

score 0 · Answer 1 · answered Feb 14 '17 at 19:20

I figured out how to use the Parallel ForEach... Here's my updated code for anyone who is interested in also running multiple instances of ghostscript:

public static void PrintingQueue(Queue<byte[]> printQueue, string printer, int copies)
    {
        Parallel.ForEach(printQueue, (currentFile) =>
        {
            currentFile = printQueue.Dequeue();
            PrintFormPdfData(currentFile, printer, copies);
        });
    }

    private static void PrintFormPdfData(byte[] pdfFormBytes, string printer, int copies)
    {
        var fileName = Path.GetTempFileName();
        using (var file = new FileStream(fileName, FileMode.Create, FileAccess.ReadWrite))
        {
            file.Write(pdfFormBytes, 0, pdfFormBytes.Length);
            using (GhostscriptProcessor processor = new GhostscriptProcessor())
            {
                List<string> switches = new List<string>();
                switches.Add("-empty");
                switches.Add("-dPrinted");
                switches.Add("-dBATCH");
                switches.Add("-dPDFFitPage");
                switches.Add("-dNOPAUSE");
                switches.Add("-dNOSAFER");
                switches.Add("-dNumRenderingThreads=3");
                switches.Add("-dNumCopies=1");
                switches.Add("-sOutputFile=%printer%" + printer);
                switches.Add("-sDEVICE=mswinpr2");
                switches.Add(fileName);
                try
                {
                    processor.StartProcessing(switches.ToArray(), null);
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex.Message);
                }
                file.Close();
            }
            File.Delete(fileName);
        }
    }

Trying to print using multiple instances of GhostScript with Parallel loop.

1 Answers1