[RESOLVED] Multi-Threaded TCP Server - threads do not close...

[marcellus]

Hello,

Below is the portion of my TCP server. The problem I am experiencing is that threads are not closed properly. My understanding was that after the given Sub completes, then the thread closes. In my program for some reason about 30% of the threads created, are never being closed. I am looking at the Task Manager and they just keep going up.

Can someone look over at my code and see if I am making any obvious mistakes? How can I find out and kill old/inactive threads?

Thanks!

Private Sub StartTCPListenerMultiThreaded()
	Dim localAddr As IPAddress = IPAddress.Parse(ip)
	TCPserver = New Sockets.TcpListener(localAddr, listeningPort)
	TCPserver.Start()			
	While True
		If TCPserver.Pending Then
			Dim t As Thread
			t = New Thread(AddressOf Me.acceptingThread)
			t.Start()
		End If
		System.Threading.Thread.Sleep(20)
	End While
End Sub

Private Sub acceptingThread()
	Dim client As TcpClient = TCPserver.AcceptTcpClient
	Dim stream As NetworkStream = client.GetStream
	client.ReceiveTimeout = 90000
	client.SendTimeout = 90000
	
	While client.Connected
		Dim bytes(1) As Byte
		Dim i As Int32
			i = stream.Read(bytes, 0, bytes.Length)
			While (i <> 0)
				'do something here with received payload
				If stream.DataAvailable = False Then
					Exit While
				End If
				i = stream.Read(bytes, 0, bytes.Length)
			End While	
	End While
	
End Sub

[Evil_Giraffe]

My first thought would be that whilst you exit the outer while loop when the client is no longer connected, that probably happens while you are waiting to read a byte from the socket. Since the client has disconnected, it is never going to send that byte, and so the thread is stuck on the Read call for ever?

[marcellus]

My first thought would be that whilst you exit the outer while loop when the client is no longer connected, that probably happens while you are waiting to read a byte from the socket. Since the client has disconnected, it is never going to send that byte, and so the thread is stuck on the Read call for ever?

Hmmm... that might be it.
When I debug the program stops on this line:

i = stream.Read(bytes, 0, bytes.Length)

If the socket is open, I am waiting for an incoming message. But let's say the client disconnects - then I have no way of knowing that.
How can I timeout this thread?

I've read in so many places that aborting threads is a bad idea. I just don't know how to kill all of those threads with those broken connections.

Most examples I've seen on-line are using the above stream.read... can anyone suggest some other way?...

[cellus205]

Sorry I can't help, just wanted to stop by and say awesome name. My name is the same and it's not one you see too often, lol. Maybe you are me in another dimension :|

[Niya]

Use BeginRead instead. Its asynchronous and hence wouldn't block. However, you will have to make that sub a little more complicated. The fact that it requires a callback procedure for receiving data is one complication. I think its worth it.

[marcellus]

I found the problem.

While client.Connected

Above line was causing this loop to continue even when the client disconnected!
I just added a safety check - simple timeout which breaks the while loop if no data is transmitted over 2 hours (which works perfect in my case).

Thanks everyone for help!