C#：异步NamedPipeServerStream管道正在关闭异常
C#：异步NamedPipeServerStream管道正在关闭异常
提问于 2012-07-12 11:08:12
我先前就同一主题提出的问题：C#: Asynchronous NamedPipeServerStream understanding，现在我有了下一个问题：
private void StartListeningPipes()
{
try
{
isPipeWorking = true;
namedPipeServerStream = new NamedPipeServerStream(PIPENAME, PipeDirection.InOut, 1, PipeTransmissionMode.Byte, PipeOptions.Asynchronous, BUFFERSIZE, BUFFERSIZE);
Console.Write("Waiting for client connection...");
while(isPipeWorking)
{
IAsyncResult asyncResult = namedPipeServerStream.BeginWaitForConnection(this.WaitForConnectionAsyncCallback, null);
Thread.Sleep(3*1000);
}
}
//// Catch the IOException that is raised if the pipe is broken or disconnected.
catch (IOException e)
{
Console.WriteLine("IOException: {0}. Restart pipe server...", e.Message);
StopListeningPipes();
StartListeningPipes();
}
//// Catch ObjectDisposedException if server was stopped. Then do nothing.
catch (ObjectDisposedException)
{
}
}
private void WaitForConnectionAsyncCallback(IAsyncResult result)
{
try
{
namedPipeServerStream.EndWaitForConnection(result);
Console.WriteLine("Client connected.");
namedPipeServerStream.WaitForPipeDrain();
byte[] buff = new byte[BUFFERSIZE];
namedPipeServerStream.Read(buff, 0, BUFFERSIZE);
string recStr = TrimNulls(buff);
Array.Clear(buff, 0, buff.Length);
Console.WriteLine();
Console.WriteLine("'"+recStr+"'");
}
catch (Exception e)
{
Console.WriteLine("Error: " + e.Message);
}
}但我得到了
The pipe is being closed Exception每次我收到客户端的消息
为什么？
我的当事人：
using (NamedPipeClientStream pipeStream = new NamedPipeClientStream(General.PIPENAME))
{
try
{
byte[] bytes = General.Iso88591Encoding.GetBytes(sendingMessage);
pipeStream.Write(bytes, 0, bytes.Length);
pipeStream.Flush();
pipeStream.WaitForPipeDrain();
}
catch (TimeoutException)
{
Console.WriteLine("Timeout error!");
}
catch (Exception e)
{
Console.WriteLine(string.Format("Error! ", e.Message));
}
}目前的最终代码是：
/// <summary>
/// Create new NamedPipeServerStream for listening to pipe client connection
/// </summary>
private void ListenForPipeClients()
{
if (!this.isListeningToClients)
return;
try
{
PipeSecurity ps = new PipeSecurity();
PipeAccessRule par = new PipeAccessRule("Everyone", PipeAccessRights.ReadWrite, System.Security.AccessControl.AccessControlType.Allow);
ps.AddAccessRule(par);
pipeClientConnection = new NamedPipeServerStream(General.PIPENAME, PipeDirection.InOut, 1, PipeTransmissionMode.Byte, PipeOptions.Asynchronous, General.BUFFERSIZE, General.BUFFERSIZE, ps);
Console.Write("Waiting for client connection...");
/*namedPipeServerStream.WaitForConnection();
OnPipeConnected(namedPipeServerStream);*/
IAsyncResult result = pipeClientConnection.BeginWaitForConnection(OnPipeConnected, pipeClientConnection);
}
catch (ObjectDisposedException)
{
//// Catch ObjectDisposedException if server was stopped. Then do nothing.
}
catch (Exception e)
{
Console.WriteLine("Error occures: {0}. Restart pipe server...", e.Message);
this.logger.Add(LogLevel.Warning, string.Format("Error occures: {0}. Restart pipe server...", e.Message));
ListenForPipeClients();
}
}
/// <summary>
/// Async callback on client connected action
/// </summary>
/// <param name="asyncResult">Async result</param>
private void OnPipeConnected(IAsyncResult asyncResult)
{
using (var conn = (NamedPipeServerStream)asyncResult.AsyncState)
{
try
{
conn.EndWaitForConnection(asyncResult);
Console.WriteLine("Client connected.");
PipeClientConnection clientConnection = new PipeClientConnection(conn, notifierSenderCache, defaultStorageTime);
}
catch (Exception e)
{
Console.WriteLine(e.Message);
this.logger.Add(LogLevel.Warning, e.Message);
}
}
ListenForPipeClients();
}回答 2
Stack Overflow用户
回答已采纳
发布于 2012-07-12 11:25:24
似乎每个客户端都需要一个单独的NamedPipeServerStream。(请注意，发现这个问题的人不是我，请看其他答案。)我可以想象，工作服务器端的外观如下(草稿代码)：
while(this.isServerRunning)
{
var pipeClientConnection = new NamedPipeServerStream(...);
try
{
pipeClientConnection.WaitForConnection();
}
catch(...)
{
...
continue;
}
ThreadPool.QueueUserWorkItem(state =>
{
// we need a separate variable here, so as not to make the lambda capture the pipeClientConnection variable, which is not recommended in multi-threaded scenarios
using(var pipeClientConn = (NamedPipeServerStream)state)
{
// do stuff
...
}
}, pipeClientConnection);
}作为附带说明，正如在对您的问题的评论中所指出的，通过循环调用BeginWaitForConnection，每3秒启动一个新的异步调用是在浪费内存(这不会浪费内存的唯一情况是，新连接的间隔小于3秒，但我怀疑您是否能够确定这一点)。您可以看到，基本上每3秒就启动一个新的异步调用，而不管最后一个调用是否仍在等待或已经完成。此外，它--再一次--没有考虑到每个客户端都需要一个单独的NamedPipeServerStream。
要解决这个问题，您需要消除循环，并使用回调方法“链接”BeginWaitForConnection调用。在使用.NET时，您将经常在异步I/O中看到类似的模式。
private void StartListeningPipes()
{
if(!this.isServerRunning)
{
return;
}
var pipeClientConnection = new NamedPipeServerStream(...);
try
{
pipeClientConnection.BeginWaitForConnection(asyncResult =>
{
// note that the body of the lambda is not part of the outer try... catch block!
using(var conn = (NamedPipeServerStream)asyncResult.AsyncState)
{
try
{
conn.EndWaitForConnection(asyncResult);
}
catch(...)
{
...
}
// we have a connection established, time to wait for new ones while this thread does its business with the client
// this may look like a recursive call, but it is not: remember, we're in a lambda expression
// if this bothers you, just export the lambda into a named private method, like you did in your question
StartListeningPipes();
// do business with the client
conn.WaitForPipeDrain();
...
}
}, pipeClientConnection);
}
catch(...)
{
...
}
}控制流将如下所示：
- 主线程StartListeningPipes()：创建NamedPipeServerStream，启动BeginWaitForConnection()
- 线程池线程1客户机#1连接，BeginWaitForConnection()回调: EndWaitForConnection()然后是StartListeningPipes()
- 线程池线程1 StartListeningPipes()：创建新的NamedPipeServerStream，BeginWaitForConnection()调用
- 线程池线程1返回到BeginWaitForConnection()回调:开始处理与连接的客户端的业务(#1)
- 线程池线程2客户机#2连接，BeginWaitForConnection()回调：.
- ..。
我认为这比使用阻塞I/O要困难得多--事实上，我不太确定我是否正确，如果您看到任何错误，请指出它--而且它也更令人困惑。
要在两个示例中暂停服务器，显然需要将this.isServerRunning标志设置为false。
Stack Overflow用户
发布于 2012-07-12 11:23:25
好的。吓死我了。每个客户端应该有一个NamedPipeServerStream。因此，如果异步操作已经完成，则必须重新创建NamedPipeServerStream。谢谢这个Multithreaded NamePipeServer in C#
应：
while(isPipeWorking)
{
IAsyncResult asyncResult = namedPipeServerStream.BeginWaitForConnection(this.WaitForConnectionAsyncCallback, null);
Thread.Sleep(3*1000);
if (asyncResult.IsCompleted)
{
RestartPipeServer();
break;
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/11450522
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