这是一个使用.NET 4.0的C#应用程序。
背景
我一直在尝试优化从多个Web服务器下载文件的应用程序的一部分。除了偶尔出现远程计算机关闭连接的情况外,一切都运行良好。我认为这可能是由于各种因素造成的,包括网络问题,电源问题等。我想在连接关闭的情况下跳过下载。但是,目前该应用程序会导致由AppDomain.CurrentDomain.UnhandledException
的处理程序拾取的异常。堆栈跟踪如下:
堆栈追踪:
Unable to read data from the transport connection:
An existing connection was forcibly closed by the remote host.
at System.Net.ConnectStream.Read(Byte[] buffer, Int32 offset, Int32 size)
at System.IO.StreamReader.ReadBuffer() at System.IO.StreamReader.ReadToEnd()
at ProjectName.ClassNetwork.DownloadFile(String _IP, Int32 _Port, String _File)
at ProjectName.FormMain.GetIFile(ClassSensor Sensor, String& RawHolder, String[] FileData)
at ProjectName.FormMain.GetLegacyData(ClassSensor Sensor)
at ProjectName.FormMain.threader_Download(Object SensorObject)
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart(Object obj)
我最初使用了WebException和Exception的try / catch但它们没有捕获到这个特定的错误。我添加了最里面的try / catch以试图避免这个问题,但无济于事。我应该提一下,这个方法是由UI线程以外的线程调用的,这可能是try / catch块看起来不起作用的部分原因。请原谅我在多线程错误捕获时成为新手!
问题:
代码:
private static object[] DownloadFile(string _IP, int _Port, string _File)
{
string uri = String.Format("http://{0}:{1}/{2}", _IP, _Port, _File);
string Status = String.Empty;
string Data = String.Empty;
HttpWebResponse Response = null;
try
{
HttpWebRequest webReq = (HttpWebRequest) WebRequest.Create(uri);
webReq.Timeout = 10000;
webReq.ReadWriteTimeout = 30000;
Response = (HttpWebResponse) webReq.GetResponse();
using (Stream dataStream = Response.GetResponseStream())
if (dataStream != null)
using (StreamReader reader = new StreamReader(dataStream))
try
{
// This line causes crashes if remote computer closes connection
Data = reader.ReadToEnd();
}
catch { } // Inner try/catch added to no avail
Response.Close();
}
catch (WebException exc)
{
// Connection Error
Status = exc.Status.ToString();
Data = String.Empty;
}
catch (Exception exc)
{
// Other error
Status = exc.Message;
Data = String.Empty;
}
if (Response != null && Response.StatusCode != HttpStatusCode.OK)
{
Status = Response.StatusCode.ToString();
Data = String.Empty;
}
return new object[] { Status, Data };
}
跟踪日志:
根据Feroze的建议,我跑了一个跟踪点,这就是结果:
System.Net Error: 0 : [2164] Exception in the
#46104728::UnhandledExceptionHandler - Stream was not readable.
System.Net Error: 0 : [2164] at System.IO.BinaryReader..ctor(Stream input, Encoding encoding)
at ProjectName.ClassNetwork.DLStream(ClassSensor Sensor)
at ProjectName.ClassNetwork.DownloadFile(ClassSensor Sensor)
at ProjectName.FormMain.GetStreamFile(ClassSensor Sensor)
at ProjectName.FormMain.threader_Download(Object SensorObject)
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncctx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart(Object obj)
答案 0 :(得分:1)
从堆栈中,我看不出这是一个你无法捕获的线程池线程抛出的异常。显然,从堆栈中看起来好像它是由你的应用程序线程调用的ConnectStream :: Read方法引发的。