Begin-EndReceive看不到到达的数据

Question

我的TCP客户端在接收数据时卡住了。

1. 已建立连接
2. 客户端发送21个字节。 （见＃5）
3. 下一个BeginReceive调用客户端永远不会调用回调。当我强制它调用EndReceive时，它会永远挂起。 IsCompleted = false。

有些数据在＃5之后到达，但问题是它永远不会进入我的应用程序。 TcpClient.Available返回135。

客户端可以发送数据，但它不会从服务器接收任何内容。



客户端使用Mono 2.6在Unity3D中运行。我只能在Unity Editor中首次启动才能重现它。第二次它开始很好但随机卡住（在编辑之外）。

那么，为什么会这样呢？

Wireshark log（设置过滤器tcp.port == 21050）。

更新：另一个例子

NoDelay = true，Blocking = false，LingerState.Enabled = false，Linger = 0

发送操作使用Socket.Send，接收操作使用Socket.Begin-End-Receive。

服务器日志：

500: Server started
7832: 1: Next receive scheduling for time 25
7863: 1: BeginReceive, available: 0
7925: 1: About to process received data: 21
7925: 1: Processing received data 21 // hello
7941: 1: Send 4  // handshake
7972: 1: Send 8  // init data
8050: 1: Send 41 // init data
8050: 1: Processing received data finished
8050: 1: Next receive scheduling for time 0
8050: 1: BeginReceive, available: 0
8237: 1: Send 86 // init data
8331: 1: About to process received data: 45
8331: 1: Processing received data 45 // set position (x,y,z)
8346: 1: Processing received data finished
8346: 1: Next receive scheduling for time 0
8346: 1: BeginReceive, available: 0
9906: 1: About to process received data: 2
9906: 1: Processing received data 2 // ping
9906: 1: Send 4 // ping response, never reaches client
9906: 1: Processing received data finished
9906: 1: Next receive scheduling for time 0
9906: 1: BeginReceive, available: 0

客户日志：

1: BeginReceive, available: 0
1: Send 21 // hello
1: EndReceive, available 0
1: About to process received data: 4
1: Processing received data 4 // handshake
1: Processing received data finished
1: Next receive scheduling for time 0
1: BeginReceive, available: 135
1: EndReceive, available 0
1: About to process received data: 135 // 8 + 41 + 86
1: Processing received data 135 // init data
1: Processing received data finished
1: Next receive scheduling for time 0
1: Send 45 // set position (x,y,z)
1: BeginReceive, available: 0
1: Send 2  // ping

Waiting ping result too long
No receive for long time, force finish, completed: False

1: EndReceive, available 0 // blocks forever

Wireshark显示4个数据包已到达。如果服务器继续发送数据包，则它们将在客户端套接字上排队（可用＆gt; 0）。

Answer 1

似乎单声道的bug与mono不支持像MS .NET一样使用异步API的非阻塞套接字这一事实有关。由于性能原因，我需要使用非阻塞模式进行发送操作。我用SendAsync和BeginReceive替换了非阻塞Send和ReceiveAsync，现在已经修复了。通过一些努力，我使SendAsync的工作速度与非阻塞Send一样快。