是什么污染了这个 switch 语句？

Question

我有一个系统正在执行以下操作，

• 将文档上传到 SharePoint
• 事件接收器将添加作业到数据库，在文档转换目录中为作业创建一个文件夹
• 目录观察器将触发 Document Conversion windows 服务
• Windows 服务将从 DB 中批量获取 10 个作业（使用主线程）
• 在启动时，Windows 服务会根据处理器的内核创建 X 个线程（使用 Parallel For）
• 然后为每个数据库作业创建具有超时的工作线程（这与并行线程不同）
• 它继续...
• 哦，在转换时……在工作线程中……我们正在调用 ActiveDirectory，登录到 DB（读取、写入）并将文档上传回 SharePoint

我设法破解它...如果我上传受密码保护的文档...并且在上传 PowerPoint 文档后不久，PowerPoint 文档会抛出密码错误异常等。

但如果两个文档之间有 60 秒的间隔，一切正常，这意味着 powerpoint 文档确实可以转换为 PDF。

以下是代码，但我不得不从中删除不必要的部分，

这是事情开始的主要类，

 Parallel.For(0, noOfThreadsToRunOnPDFServer, new ParallelOptions { MaxDegreeOfParallelism = noOfThreadsToRunOnPDFServer },
    i =>
    {
        this.docConvService.ProcessDocuments(i);
    });

那么转换就在这里发生了……

using System;
using System.IO;
using System.Runtime.ExceptionServices;
using System.Threading;

namespace PDFService
{
    public class AsposePDFConverter : IPDFConverter
    {
        private IDocConversionSettings settings;
        private ExceptionDispatchInfo conversionException = null;
        public enum SupportedExtensions
        {
            Doc,
            Docx,
            Xls,
            Xlsx,
            Pdf,
            Pps,
            Ppsx,
            Ppt,
            Pptx,
            Txt,
            Html,
            Mhtml,
            Xhtml,
            Msg,
            Eml,
            Emlx,
            One,
            Vsd,
            Vsdx,
            Vss,
            Vssx
        }

        public AsposePDFConverter(IDocConversionSettings settings)
        {
            this.settings = settings;
        }

        private void SyncThreadStartWithTimeout(ThreadStart threadStart, TimeSpan timeout)
        {
            Thread workerThread = new Thread(threadStart);
            workerThread.Start();

            bool finished = workerThread.Join(timeout);
            if (!finished)
            {
                workerThread.Abort();
                throw new ConversionTimeoutException("PDF Conversion exceeded timeout value");
            }
        }

        public MemoryStream ConvertToPDF(string documentName, Stream docContent, double timeoutMS)
        {
            this.conversionException = null;

            MemoryStream outStream = null;
            MemoryStream inStream = new MemoryStream();
            docContent.CopyTo(inStream);
            inStream.Seek(0, SeekOrigin.Begin);

            SupportedExtensions documentExtension;
            string szExtension = Path.GetExtension(documentName).TrimStart('.');
            if (Enum.TryParse(szExtension, true, out documentExtension))
            {
                switch (documentExtension)
                {
                    case SupportedExtensions.Doc:
                    case SupportedExtensions.Docx:
                    case SupportedExtensions.Txt:
                    case SupportedExtensions.Html:
                    case SupportedExtensions.Mhtml:
                    case SupportedExtensions.Xhtml:
                        SyncThreadStartWithTimeout(
                                () => { outStream = ConvertWordsToPDF(inStream); },
                                TimeSpan.FromMilliseconds(timeoutMS));
                        break;
                    case SupportedExtensions.Pps:
                    case SupportedExtensions.Ppsx:
                    case SupportedExtensions.Ppt:
                    case SupportedExtensions.Pptx:
                        SyncThreadStartWithTimeout(
                                () => { outStream = ConvertSlidesToPDF(inStream); },
                                TimeSpan.FromMilliseconds(timeoutMS));
                        break;
                }

                // Conversion happens on sub-threads so they can time out, if they throw an exception, throw it from this thread
                if (this.conversionException != null)
                    this.conversionException.Throw();

                return outStream;
            }
            else
            {
                throw new FormatNotSupportedException("Document type is not supported");
            }
        }

        private MemoryStream ConvertWordsToPDF(Stream docContent)
        {
            try
            {
                Aspose.Words.License lic = new Aspose.Words.License();
                lic.SetLicense(this.settings.AsposeLicensePath);
                Aspose.Words.Document doc = new Aspose.Words.Document(docContent);

                MemoryStream stream = new MemoryStream();
                doc.Save(stream, Aspose.Words.SaveFormat.Pdf);
                return stream;
            }
            catch (Exception ex)
            {
                this.conversionException = ExceptionDispatchInfo.Capture(ex);
                return null;
            }
        }

        private MemoryStream ConvertSlidesToPDF(Stream docContent)
        {
            try
            { 
                Aspose.Slides.License lic = new Aspose.Slides.License();
                lic.SetLicense(this.settings.AsposeLicensePath);
                using (Aspose.Slides.Presentation presentation = new Aspose.Slides.Presentation(docContent))
                {
                    MemoryStream stream = new MemoryStream();
                    presentation.Save(stream, Aspose.Slides.Export.SaveFormat.Pdf);
                    return stream;
                }
            }
            catch (Exception ex)
            {
                this.conversionException = ExceptionDispatchInfo.Capture(ex);
                return null;
            }
        }

    }
}

错误是，

文档 PDF 转换期间出错。详细信息是：PDFConversionID： 6061，文档名称：powerpoint.ppsx，WebURL：已删除，上传者： 已移除，转换持续时间：00:01:06.3072410

Aspose.Words.IncorrectPasswordException: 文档密码是 不正确。在 Aspose.Words.Document。 （流，加载选项）
在 Aspose.Words.Document。 （流，加载选项）在 DocumentPDFConversionService.AsposePDFConverter.ConvertWordsToPDF(Stream docContent) 在...中

如您所见，发生了一些非常可疑的事情

Answer 1

您在多个线程中使用 this.docConvService 的同一实例，因此您的 conversionException 属性可能是由受密码保护的文档在处理其他文档时写入的。您应该实例化 AsposePDFConverter 的新实例，或更改返回异常的方式，例如在 ConvertToPDF 返回的结果对象中，其中包含 MemoryStream 和您的错误。

每个请求的单独实例：

Parallel.For(0, noOfThreadsToRunOnPDFServer, new ParallelOptions { MaxDegreeOfParallelism = noOfThreadsToRunOnPDFServer },
    i =>
    {
        new AsposePdfConverter(settings).ProcessDocuments(i);
    });

返回一个结果对象：

 public ConversionResult ConvertToPDF(string documentName, Stream docContent, double timeoutMS)
{
    /** Your code **/
    return new ConversionResult() 
        {
        MemoryStream = memoryStream,
        ConversionException = conversionException
        };
}

class ConversionResult {
    MemoryStream MemoryStream {get;set;}
    ExceptionDispatchInfo ConversionException {get;set;}
}