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TcpClient close() method socket leak

TcpClient close() method socket leak

when i use TcpClient to open a connection, send data and close the TcpClient
with myTcpClientInstance.Close(); it takes 60 seconds for the actual socket
on the client machine to close per my network app the computer fills up w/
thousands of these

[System Process]:0 TCP foobox:8888 localhost:2188 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2189 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2190 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2191 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2192 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2193 TIME_WAIT

until the "Only one usage of each socket address" error occures. How to
work around this? I need to open connect, send data, and close it. i can not
share connections in my case i have to open, send and close and have the
close truely close. and i have to do more then 3k of these in 60 seconds. I
know this is possible because I have a c version of the client that uses c
sockets and it works fine and does not fill with thousands of:

[System Process]:0 TCP foobox:8888 localhost:2188 TIME_WAIT

Is this a limitation of TcpClient ? or is there a way to truely close a
TcpClient imediatly? i tried setting linger option false, no delay true,
timeout 0 etc. still no progress the client sockets all get used up w/
thousands of

[System Process]:0 TCP foobox:8888 localhost:2188 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2189 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2190 TIME_WAIT

until the "Only one usage of each socket address" error occures.

here is what my client code looks like:

TcpClient myclient;
myclient = new TcpClient();
LingerOption lingerOption = new LingerOption (false, 0);
myclient.LingerState = lingerOption;
myclient.NoDelay = true;
myclient.ReceiveTimeout = 0;
myclient.Connect("foobox", 8888);
NetworkStream networkStream ;
networkStream = myclient.GetStream();
StreamWriter streamWriter ;
streamWriter = new StreamWriter(networkStream);
string strData = "";
strData += "helloworld\0";
streamWriter.WriteLine(strData);
streamWriter.Flush();
streamWriter.Close() ;
networkStream.Close();
myclient.Close();

something missing? should i do more then close? i tried shutdown too.. no
progress

here is the dummy server code if it matters:

public static void Main()
{
TcpListener tcpListener = new TcpListener(8082);
tcpListener.Start();
Console.WriteLine("Server Started") ;
while(true)
{
Socket socketForClient = tcpListener.AcceptSocket();
try
{
if(socketForClient.Connected)
{
Console.WriteLine("Client connected");
NetworkStream networkStream = new NetworkStream(socketForClient);
StreamReader streamReader = new StreamReader(networkStream);
string line = streamReader.ReadLine();
streamReader.Close();
Console.WriteLine("Read:" +line);
}
socketForClient.Shutdown(System.Net.Sockets.Socket Shutdown.Both);
socketForClient.Close();
Console.WriteLine("Client disconnected");
GC.Collect();
Console.WriteLine("Garbage Collected");
}
catch(Exception e)
{
Console.WriteLine(e.ToString()) ;
}
}
}
Jul 21 '05 #1
3 7926
also, even after the client executable is unloaded from memory the ever evil
socket entries remain for 60 seconds:
[System Process]:0 TCP foobox:8888 localhost:2188 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2189 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2190 TIME_WAIT

is it that i can only do 3000 open, send, close in every 60 seconds per a
limitation w/ the TcpClient or is there something else i could try?

"Daniel" <so*******************@yahoo.com> wrote in message
news:%2****************@TK2MSFTNGP09.phx.gbl...
TcpClient close() method socket leak

when i use TcpClient to open a connection, send data and close the TcpClient with myTcpClientInstance.Close(); it takes 60 seconds for the actual socket on the client machine to close per my network app the computer fills up w/
thousands of these

[System Process]:0 TCP foobox:8888 localhost:2188 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2189 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2190 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2191 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2192 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2193 TIME_WAIT

until the "Only one usage of each socket address" error occures. How to
work around this? I need to open connect, send data, and close it. i can not share connections in my case i have to open, send and close and have the
close truely close. and i have to do more then 3k of these in 60 seconds. I know this is possible because I have a c version of the client that uses c
sockets and it works fine and does not fill with thousands of:

[System Process]:0 TCP foobox:8888 localhost:2188 TIME_WAIT

Is this a limitation of TcpClient ? or is there a way to truely close a
TcpClient imediatly? i tried setting linger option false, no delay true,
timeout 0 etc. still no progress the client sockets all get used up w/
thousands of

[System Process]:0 TCP foobox:8888 localhost:2188 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2189 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2190 TIME_WAIT

until the "Only one usage of each socket address" error occures.

here is what my client code looks like:

TcpClient myclient;
myclient = new TcpClient();
LingerOption lingerOption = new LingerOption (false, 0);
myclient.LingerState = lingerOption;
myclient.NoDelay = true;
myclient.ReceiveTimeout = 0;
myclient.Connect("foobox", 8888);
NetworkStream networkStream ;
networkStream = myclient.GetStream();
StreamWriter streamWriter ;
streamWriter = new StreamWriter(networkStream);
string strData = "";
strData += "helloworld\0";
streamWriter.WriteLine(strData);
streamWriter.Flush();
streamWriter.Close() ;
networkStream.Close();
myclient.Close();

something missing? should i do more then close? i tried shutdown too.. no
progress

here is the dummy server code if it matters:

public static void Main()
{
TcpListener tcpListener = new TcpListener(8082);
tcpListener.Start();
Console.WriteLine("Server Started") ;
while(true)
{
Socket socketForClient = tcpListener.AcceptSocket();
try
{
if(socketForClient.Connected)
{
Console.WriteLine("Client connected");
NetworkStream networkStream = new NetworkStream(socketForClient);
StreamReader streamReader = new StreamReader(networkStream);
string line = streamReader.ReadLine();
streamReader.Close();
Console.WriteLine("Read:" +line);
}
socketForClient.Shutdown(System.Net.Sockets.Socket Shutdown.Both);
socketForClient.Close();
Console.WriteLine("Client disconnected");
GC.Collect();
Console.WriteLine("Garbage Collected");
}
catch(Exception e)
{
Console.WriteLine(e.ToString()) ;
}
}
}

Jul 21 '05 #2
The TIME_WAIT state for the closed socket is normal. Even your 'c' program should
have had sockets in the TIME_WAIT state after they where closed. Some links to
explanations of this:

http://support.microsoft.com/default...b;en-us;137984

"NOTE: It is normal to have a socket in the TIME_WAIT state for a long period of
time. The time is specified in RFC793 as twice the Maximum Segment Lifetime (MSL).
MSL is specified to be 2 minutes. So, a socket could be in a TIME_WAIT state for
as long as 4 minutes. Some systems implement different values (less than 2
minutes) for the MSL"

http://tangentsoft.net/wskfaq/articl...gging-tcp.html

"Problem: Netstat shows lots of sockets in the TIME_WAIT state. What's wrong?"
"Solution: Nothing's wrong. TIME_WAIT is absolutely normal. [clipped] Thus,
TIME_WAIT usually lasts 30-120 seconds"

On the other hand I'm not sure why your would die with 3k of socket outstanding.
That seems a little low although the max number is dependent on OS memory so it
varies from machine to machine.

There is a 'resuse address' option also for sockets but I'm not sure if that would
help.

Mike

--
POST BY: http://www.dotNET.us - Need .NET? Just ask, Please dotNET.us
Jul 21 '05 #3
TIME_WAIT is normal behaviour for proper TCP session closure.
Reference blurb from RFC 793 with explanation as to why.
The dirty way to close it is to use RST TCP packet header flag and kill the
connection instead of shutting it down. This is not something you would
consider to be "proper way"
The reason as to why TCP_WAIT is hanging around for 60 seconds - berkley
implementation of a socket states Maximum Segment Lifetime to be 30 seconds,
hence 2 times that is 60 (read below)

The protocol places no restriction on a particular connection being
used over and over again. A connection is defined by a pair of
sockets. New instances of a connection will be referred to as
incarnations of the connection. The problem that arises from this is
-- "how does the TCP identify duplicate segments from previous
incarnations of the connection?" This problem becomes apparent if the
connection is being opened and closed in quick succession, or if the
connection breaks with loss of memory and is then reestablished.

To avoid confusion we must prevent segments from one incarnation of a
connection from being used while the same sequence numbers may still
be present in the network from an earlier incarnation. We want to
assure this, even if a TCP crashes and loses all knowledge of the
sequence numbers it has been using. When new connections are created,
an initial sequence number (ISN) generator is employed which selects a
new 32 bit ISN. The generator is bound to a (possibly fictitious) 32
bit clock whose low order bit is incremented roughly every 4
microseconds. Thus, the ISN cycles approximately every 4.55 hours.
Since we assume that segments will stay in the network no more than
the Maximum Segment Lifetime (MSL) and that the MSL is less than 4.55
hours we can reasonably assume that ISN's will be unique.
"Daniel" wrote:
also, even after the client executable is unloaded from memory the ever evil
socket entries remain for 60 seconds:
[System Process]:0 TCP foobox:8888 localhost:2188 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2189 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2190 TIME_WAIT

is it that i can only do 3000 open, send, close in every 60 seconds per a
limitation w/ the TcpClient or is there something else i could try?

"Daniel" <so*******************@yahoo.com> wrote in message
news:%2****************@TK2MSFTNGP09.phx.gbl...
TcpClient close() method socket leak

when i use TcpClient to open a connection, send data and close the

TcpClient
with myTcpClientInstance.Close(); it takes 60 seconds for the actual

socket
on the client machine to close per my network app the computer fills up w/
thousands of these

[System Process]:0 TCP foobox:8888 localhost:2188 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2189 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2190 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2191 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2192 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2193 TIME_WAIT

until the "Only one usage of each socket address" error occures. How to
work around this? I need to open connect, send data, and close it. i can

not
share connections in my case i have to open, send and close and have the
close truely close. and i have to do more then 3k of these in 60 seconds.

I
know this is possible because I have a c version of the client that uses c
sockets and it works fine and does not fill with thousands of:

[System Process]:0 TCP foobox:8888 localhost:2188 TIME_WAIT

Is this a limitation of TcpClient ? or is there a way to truely close a
TcpClient imediatly? i tried setting linger option false, no delay true,
timeout 0 etc. still no progress the client sockets all get used up w/
thousands of

[System Process]:0 TCP foobox:8888 localhost:2188 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2189 TIME_WAIT
[System Process]:0 TCP foobox:8888 localhost:2190 TIME_WAIT

until the "Only one usage of each socket address" error occures.

here is what my client code looks like:

TcpClient myclient;
myclient = new TcpClient();
LingerOption lingerOption = new LingerOption (false, 0);
myclient.LingerState = lingerOption;
myclient.NoDelay = true;
myclient.ReceiveTimeout = 0;
myclient.Connect("foobox", 8888);
NetworkStream networkStream ;
networkStream = myclient.GetStream();
StreamWriter streamWriter ;
streamWriter = new StreamWriter(networkStream);
string strData = "";
strData += "helloworld\0";
streamWriter.WriteLine(strData);
streamWriter.Flush();
streamWriter.Close() ;
networkStream.Close();
myclient.Close();

something missing? should i do more then close? i tried shutdown too.. no
progress

here is the dummy server code if it matters:

public static void Main()
{
TcpListener tcpListener = new TcpListener(8082);
tcpListener.Start();
Console.WriteLine("Server Started") ;
while(true)
{
Socket socketForClient = tcpListener.AcceptSocket();
try
{
if(socketForClient.Connected)
{
Console.WriteLine("Client connected");
NetworkStream networkStream = new NetworkStream(socketForClient);
StreamReader streamReader = new StreamReader(networkStream);
string line = streamReader.ReadLine();
streamReader.Close();
Console.WriteLine("Read:" +line);
}
socketForClient.Shutdown(System.Net.Sockets.Socket Shutdown.Both);
socketForClient.Close();
Console.WriteLine("Client disconnected");
GC.Collect();
Console.WriteLine("Garbage Collected");
}
catch(Exception e)
{
Console.WriteLine(e.ToString()) ;
}
}
}


Jul 21 '05 #4

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