c# - WebSocket异常关闭不返回ReceiveAsync

Question

我在服务器上有一个线程用于处理通过 WebSocket 连接从客户端接收的数据:

    public HttpResponseMessage Get()
    {
        if (HttpContext.Current.IsWebSocketRequest)
        {
            HttpContext.Current.AcceptWebSocketRequest(ProcessWebSocket);
        }

        return new HttpResponseMessage(HttpStatusCode.SwitchingProtocols);
    }

    private async Task ProcessWebSocket(AspNetWebSocketContext context)
    {
        WebSocket webSocket = context.WebSocket;    //Gets the current WebSocket object. 
        const int maxMessageSize = 1024;
        byte[] receivedDataBuffer = new byte[maxMessageSize];
        logger.Debug("WSC-New WebSocket connection");
        while (webSocket.State == WebSocketState.Open)
        {
            var timeOut = new CancellationTokenSource(70000).Token;
            WebSocketReceiveResult webSocketReceiveResult = await webSocket.ReceiveAsync(new ArraySegment<byte>(receivedDataBuffer), timeOut);
            //If input frame is cancelation frame, send close command. 
            if (webSocketReceiveResult.MessageType == WebSocketMessageType.Close)
            {
                await webSocket.CloseAsync(WebSocketCloseStatus.NormalClosure, String.Empty, CancellationToken.None);
                logger.Debug("WSC-Close WebSocket connection frame received");
            }
            else
            {
                //Process received data....
            }
        }
        logger.Debug("WSC-WebSocket closed, WebSocket state: {0}", webSocket.State.ToString());
    }

只要另一端正确关闭 WebSocket 连接，我就会在最后收到记录器消息，指出 websocket 已关闭，这意味着该线程已正确终止。如果客户端进入休眠状态或程序突然停止，则不会发生正常的 WebSocket 关闭。在这种情况下，webSocket.ReceiveAsync 永远不会返回。我担心如果启动了足够多的这些线程但从未终止，我可能会发生严重的内存泄漏。超时取消 token 应该在 70 秒后返回，但它并没有发生。如果我在这种情况下尝试从另一个线程访问 webSocket 对象，则会出现以下异常:无法访问已处置的对象。

如何从 await webSocket.ReceiveAsync(new ArraySegment(receivedDataBuffer), timeOut); 返回正确关闭此线程？

Answer 1

问题:

几乎任何连接的突然关闭都会导致另一个套接字再也无法获取数据，这会导致您的套接字像您所说的那样保持打开状态。

解决方案:

尝试使用 Keep-Alive 来确定连接何时超时，另一种解决方案是使用一个单独的线程，该线程可能会被杀死以丢弃它，但是我不确定这对您来说效果如何。

启动套接字EX:

Thread X = new Thread(() => {
    Connect();
});
X.Start();

结束套接字EX:

X.Abort();
// You could also force a Garbage Collection using
GC.Collect();