Unexplainable Error "One Usage per IP Socket"

[Grant Richard]

Using the TcpListener and TcpClient I created a program that just sends and
receives a short string - over and over again. The program is fine until it
gets to around 1500 to 1800 messages. At that time, I get a SocketException
with the message "Only one usage of each socket address (protocol/network
address/port) is normally permitted". This happen if you use localhost or
between two distinct computers. And, for a period of time after the error
(~1 - 5 minutes), the program errors out on the first Client socket
connection.

The message is bogus since its works for the first 1000 or so times. It's
something else and the best it can do is this error. At first I thought is
was not destructing the connection but I explicitly called Dispose and also
garbage collected after every 500 connections - but that did not work.

I am using VS 2003 / .NET Framework 1.1. But, the same thing happens with
VS.NET and .NET FW 1.0. I searched google and the knowledge base but nothing
points to this error that was helpful.

Any advice or fix would be appreciated. The stripped down code is below.

Thanks in advance,
// code for NetStreamtest
using System;
using System.Net.Sockets;
using System.Net;
using System.Threading;
using System.Security.Permissions;

/************************************************** *************
*
*
C:\Temp\vs.net\NetStreamTest\bin\Debug>netstreamte st localhost
Connecting to host->127.0.0.1
Number is 0 9/20/2003 3:19:15 PM
Number is 200 9/20/2003 3:19:15 PM
Number is 400 9/20/2003 3:19:16 PM
Number is 600 9/20/2003 3:19:16 PM
Number is 800 9/20/2003 3:19:17 PM
Number is 1000 9/20/2003 3:19:17 PM
Number is 1200 9/20/2003 3:19:18 PM
Number is 1400 9/20/2003 3:19:18 PM
Number is 1600 9/20/2003 3:19:19 PM
Number is 1800 9/20/2003 3:19:19 PM
CLIENT:Exception->System.Net.Sockets.SocketException: Only one usage of each
soc
ket address (protocol/network address/port) is normally permitted
at System.Net.Sockets.TcpClient.Connect(String hostname, Int32 port)
at System.Net.Sockets.TcpClient..ctor(String hostname, Int32 port)
at NetStreamTest.TCPCommunication.GoClient(String message) in
c:\temp\vs.net\
netstreamtest\netstreamtest.cs:line 109
Main:Exception at i =1961: System.Net.Sockets.SocketException: Only one
usage of
each socket address (protocol/network address/port) is normally permitted
at NetStreamTest.TCPCommunication.GoClient(String message) in
c:\temp\vs.net\
netstreamtest\netstreamtest.cs:line 123
at NetStreamTest.NetStreamTestMain.Main(String[] args) in
c:\temp\vs.net\nets
treamtest\netstreamtest.cs:line 35

Unhandled Exception: System.Net.Sockets.SocketException: Only one usage of
each
socket address (protocol/network address/port) is normally permitted
at NetStreamTest.NetStreamTestMain.Main(String[] args) in
c:\temp\vs.net\nets
treamtest\netstreamtest.cs:line 45
************************************************** **************/

namespace NetStreamTest
{
class NetStreamTestMain
{
[STAThread]
static void Main(string[] args)
{
TCPCommunication tcc = null;
Thread th = null;
int i=0;

string s = "localhost";

if( args.Length > 0 )
if( args[0].Length > 0 )
s = args[0];

try
{
tcc = new TCPCommunication(s);
th = new Thread(new ThreadStart( tcc.GoServer ));
th.Start();

Thread.Sleep( 2 ); // wait for server to start...

for(i=0; i < 4000; i++) // it will fault before this is done
{
tcc.GoClient(i.ToString() + ":THIS IS A TEST ");
if( i % 200 == 0 ) // just so there is status
Console.Out.WriteLine("Number is " + i.ToString() + " " +
DateTime.Now.ToString() );
}

Thread.Sleep(2); // hopefully to clear out messages
}
catch (Exception e)
{
Console.WriteLine("Main:Exception at i ={0}: {1}", i ,e);
throw( e ); // re-throw the exception to end
}
finally
{
if( th != null )
th.Abort();
}
}
}

class TCPCommunication
{
private Int32 port = 812;
private bool DisplayItClient = false;
private bool DisplayItServer = false;
private string ServerName;

public TCPCommunication( string ServerName )
{
this.ServerName = ServerName;
}
[SocketPermission(SecurityAction.Demand, Unrestricted=true)]
public void GoServer()
{
bool notDone = true;
IPHostEntry heserver = Dns.Resolve(this.ServerName);
Console.Out.WriteLine("Connecting to host->" +
heserver.AddressList[0].ToString() );

TcpListener server = new TcpListener( heserver.AddressList[0], port);
server.Start();

if( this.DisplayItServer )
Console.Out.WriteLine("In GoServer thread");

while( notDone )
{
try
{
Socket s = server.AcceptSocket();
NetworkStream stream = new NetworkStream( s );

string response = this.ReadMessage(stream, this.DisplayItServer);
this.WriteMessage(response+" ***** GOT IT! ***** ", stream ,
this.DisplayItServer);

if( this.DisplayItServer )
Console.Out.WriteLine("SERVER: response = " + response);
}
catch (Exception e)
{
Console.WriteLine("SERVER:Exception-> {0}", e);
notDone = false;
}
}

server.Stop();
}

public void GoClient(string message )
{
try
{
if( this.DisplayItClient )
Console.Out.WriteLine("CLIENT:Msg"+message);

TcpClient client = new TcpClient(this.ServerName, port);
NetworkStream stream = client.GetStream();
this.WriteMessage(message,stream,this.DisplayItCli ent);

string response = this.ReadMessage(stream,this.DisplayItClient);
if( this.DisplayItClient )
Console.Out.WriteLine("response = "+response);

// Close everything.
client.Close();
}
catch (Exception e)
{
Console.WriteLine("CLIENT:Exception->{0}", e);
throw( e );
}

}
void WriteMessage( string message, NetworkStream ns, bool log )
{
// Translate the passed message into ASCII and store it as a Byte array.
Byte[] data = System.Text.Encoding.ASCII.GetBytes(message);
// Send the message to the connected TcpServer.
ns.Write(data, 0, data.Length);

if( log )
Console.WriteLine("Sent: {0}", message);
}

string ReadMessage( NetworkStream ns, bool log )
{
// Buffer to store the response bytes.
Byte [] data = new Byte[512];

// String to store the response ASCII representation
String responseData = String.Empty;

// Read the first batch of the TcpServer response bytes.
Int32 bytes = ns.Read(data, 0, data.Length);
responseData = System.Text.Encoding.ASCII.GetString(data, 0, bytes);

if( log )
Console.WriteLine("Sent: {0}", responseData);

return responseData;
}

}
}

[Felix Wang]

Hi Grant,

Thanks for posting. Currently I am conducting research on your program. I
will get back to you as soon as possible.

Have a nice day!

Regards,

Felix Wang
Microsoft Online Partner Support
Get Secure! - www.microsoft.com/security
This posting is provided "as is" with no warranties and confers no rights.

[Felix Wang]

Hi Grant,

I think the problem is that you have opened too many sockets on the server
side without closing them.

On my machine, I can reach around 3900 before the exception pops up. After
adding one line, the program can run continuously:

s.Close();

I put this line in your GoServer() method to close the Socket s. You may
also close the NetworkStream by calling stream.Close(), and call
s.ShutDown() method first to ensure all data is sent or received.

I hope this helps.

Regards,

Felix Wang
Microsoft Online Partner Support
Get Secure! - www.microsoft.com/security
This posting is provided "as is" with no warranties and confers no rights.

[Grant Richard]

Yes and no. It did solve the initial problem. The changed loop looks like.

....

while( notDone )
{
try

{
Socket s = server.AcceptSocket();
NetworkStream stream = new NetworkStream( s );
string response = this.ReadMessage(stream, this.DisplayItServer);
this.WriteMessage(response+" ***** GOT IT! ***** ", stream ,
this.DisplayItServer);
if( this.DisplayItServer )
Console.Out.WriteLine("SERVER: response = " + response);
s.Close();
} ...

That worked fine but at around 28000 interactions, the same message cropped
up.

Number is 28000 10/20/2003 8:39:42 AM
Number is 28200 10/20/2003 8:39:43 AM
Number is 28400 10/20/2003 8:39:43 AM
Number is 28600 10/20/2003 8:39:44 AM
CLIENT:Exception->System.Net.Sockets.SocketException: Only one usage of each
soc
ket address (protocol/network address/port) is normally permitted
at System.Net.Sockets.TcpClient.Connect(String hostname, Int32 port)
at System.Net.Sockets.TcpClient..ctor(String hostname, Int32 port)
at NetStreamTest.TCPCommunication.GoClient(String message) in
c:\temp\vs.net\
netstreamtest\netstreamtest.cs:line 145
Main:Exception at i =28613: System.Net.Sockets.SocketException: Only one
usage o
f each socket address (protocol/network address/port) is normally permitted
at NetStreamTest.TCPCommunication.GoClient(String message) in
c:\temp\vs.net\
netstreamtest\netstreamtest.cs:line 159
at NetStreamTest.NetStreamTestMain.Main(String[] args) in
c:\temp\vs.net\nets
treamtest\netstreamtest.cs:line 69

"Felix Wang" <v-*****@online.microsoft.com> wrote in message
news:NR**************@cpmsftngxa06.phx.gbl...

Hi Grant,

I think the problem is that you have opened too many sockets on the server
side without closing them.

On my machine, I can reach around 3900 before the exception pops up. After
adding one line, the program can run continuously:

s.Close();

I put this line in your GoServer() method to close the Socket s. You may
also close the NetworkStream by calling stream.Close(), and call
s.ShutDown() method first to ensure all data is sent or received.

I hope this helps.

Regards,

Felix Wang
Microsoft Online Partner Support
Get Secure! - www.microsoft.com/security
This posting is provided "as is" with no warranties and confers no rights.

[Felix Wang]

Hi Grant,

Thanks for your reply.

The same program can run to 70000 without any exception on my machine. I
did not continue because it took too long and made my computer become slow.
If you open a command line interface and input the "netstat" command, you
will see how many TCP connections are active.

I think that everything has a limitation. If you could let us know what
goal you are trying to achieve, maybe we can be more helpful to you on this
issue.

Regards,

Felix Wang
Microsoft Online Partner Support
Get Secure! - www.microsoft.com/security
This posting is provided "as is" with no warranties and confers no rights.

[Felix Wang]

Hi Grant,

Let me elaborate a little bit more on this issue.

I think that every operating system has its limits. On my Windows 2003
Server, I was able to loop for more than 70000 times. However, the CPU
utilization keeps at 100%. When we close the session by calling "Close()",
the connection is not closed immediately. If we use "NetStat" to view the
TCP states, we can see a lot of connections have the status as "TIME_WAIT".
On your machine, I guess that 28000 loops is too many for the system.

I still think that If you could let us know what you are trying to achieve,
we may provide you with some workarounds.

Regards,

Felix Wang
Microsoft Online Partner Support
Get Secure! - www.microsoft.com/security
This posting is provided "as is" with no warranties and confers no rights.

[Felix Wang]

Hi Grant,

I have found some additional information on the "TIME_WAIT" status for you:

Problem: Netstat shows lots of sockets in the TIME_WAIT state. What's
wrong?
Solution: Nothing's wrong. TIME_WAIT is absolutely normal. If you go
through the state-transition diagram above, you see that every socket that
gets closed normally goes through this state after it's closed. The
TIME_WAIT state is a safety mechanism, to catch stray packets for that
connection after the connection is "officially" closed. Since the maximum
time that such stray packets can exist is 2 times the "maximum segment
lifetime" (the time for a packet to go from your machine to the remote peer
and for the response to come back), the TIME_WAIT state lasts for 2 * MSL.
The only tricky bit is, there is no easy way to estimate MSL on the fly, so
stacks traditionally hard-code a value for it, from 15 to 60 seconds. Thus,
TIME_WAIT usually lasts 30-120 seconds.

I think that when we run the program, there will be too many sockets enter
into the "TIME_WAIT" state and as a result, the system refuses further
connection. For a previous post discussing a similar issue, you may visit
the following site:

http://groups.google.com/groups?hl=e...readm=OUreRodj
DHA.2364%40TK2MSFTNGP11.phx.gbl&rnum=10&prev=/groups%3Fhl%3Den%26lr%3D%26ie%
3DUTF-8%26oe%3DUTF-8%26q%3D%2522Only%2Bone%2Busage%2Bof%2Beach%2Bsock et%2Bad
dress%2522%2BSocketException

I hope the information is useful to you.

Regards,

Felix Wang
Microsoft Online Partner Support
Get Secure! - www.microsoft.com/security
This posting is provided "as is" with no warranties and confers no rights.

[Grant Richard]

My understanding now is that after a certain number of messages going back
and forth, the server socket is overwhelmed and spews out the misleading
error message. This makes sense expect I'd prefer to have a error message
that is not misleading. But, if you goal is to provide a high
speed/throughput interface, how do you avoid such a problem?

As suggestions would be appreciated.
Grant
"Grant Richard" <dg**********@hotmail.com> wrote in message
news:Oc**************@TK2MSFTNGP11.phx.gbl...

Yes and no. It did solve the initial problem. The changed loop looks like.
....

while( notDone )
{
try

{
Socket s = server.AcceptSocket();
NetworkStream stream = new NetworkStream( s );
string response = this.ReadMessage(stream, this.DisplayItServer);
this.WriteMessage(response+" ***** GOT IT! ***** ", stream ,
this.DisplayItServer);
if( this.DisplayItServer )
Console.Out.WriteLine("SERVER: response = " + response);
s.Close();
} ...

That worked fine but at around 28000 interactions, the same message cropped up.

Number is 28000 10/20/2003 8:39:42 AM
Number is 28200 10/20/2003 8:39:43 AM
Number is 28400 10/20/2003 8:39:43 AM
Number is 28600 10/20/2003 8:39:44 AM
CLIENT:Exception->System.Net.Sockets.SocketException: Only one usage of each soc
ket address (protocol/network address/port) is normally permitted
at System.Net.Sockets.TcpClient.Connect(String hostname, Int32 port)
at System.Net.Sockets.TcpClient..ctor(String hostname, Int32 port)
at NetStreamTest.TCPCommunication.GoClient(String message) in
c:\temp\vs.net\
netstreamtest\netstreamtest.cs:line 145
Main:Exception at i =28613: System.Net.Sockets.SocketException: Only one
usage o
f each socket address (protocol/network address/port) is normally permitted at NetStreamTest.TCPCommunication.GoClient(String message) in
c:\temp\vs.net\
netstreamtest\netstreamtest.cs:line 159
at NetStreamTest.NetStreamTestMain.Main(String[] args) in
c:\temp\vs.net\nets
treamtest\netstreamtest.cs:line 69

"Felix Wang" <v-*****@online.microsoft.com> wrote in message
news:NR**************@cpmsftngxa06.phx.gbl...

Hi Grant,

I think the problem is that you have opened too many sockets on the server side without closing them.

On my machine, I can reach around 3900 before the exception pops up. After adding one line, the program can run continuously:

s.Close();

I put this line in your GoServer() method to close the Socket s. You may
also close the NetworkStream by calling stream.Close(), and call
s.ShutDown() method first to ensure all data is sent or received.

I hope this helps.

Regards,

Felix Wang
Microsoft Online Partner Support
Get Secure! - www.microsoft.com/security
This posting is provided "as is" with no warranties and confers no rights.

[Felix Wang]

Hi Grant,

Thanks for your feedback. You new question is quite difficult to answer.
Here are two facts:

1. On my Windows 2003 Server with 512MB RAM and 600MHZ CPU, the program can
run continuously.
2. On my Windows XP Pro with 256MB RAM and 733MHZ CPU, the program stops at
around 9800 loops.

Theoretically, there seems to be no problem with the program itself. It is
some other factors that matters. As general rules, the server should have a
good operating system, a powerful CPU, sufficient memory and so on.
Sometimes we even use round-robin clustering to further enhance the service
availibility and performance.

Probably we can try adjusing the time_wait delay
(HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servi ces\Tcpip\Parameters\TcpTi
medWaitDelay). But this can have detrimental effects as well.

I hope this makes sense to you.

Regards,

Felix Wang
Microsoft Online Partner Support
Get Secure! - www.microsoft.com/security
This posting is provided "as is" with no warranties and confers no rights.