problem in multithreading ? !!!

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C#

private void OnReceive(IAsyncResult ar)
 {

 clientSocket.EndReceive(ar);

//Convert the bytes received into an object of type Data
 Data msgReceived = new Data(byteData);

//Accordingly process the message received
 switch (msgReceived.cmdCommand)
 {

 case Command.openForm:

form1 f=new form1();
 the form is waiting here!!! \\\\\\ f.show();


break;

 }


//Start listening to receive more data from the user
 clientSocket.BeginReceiveFrom(byteData, 0, byteData.Length, SocketFlags.None, ref epServer,
 new AsyncCallback(OnReceive), null);

 }

Posted 15-Oct-12 7:34am

farid wahed

Updated 15-Oct-12 7:40am

ridoy

v2

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Sergey Alexandrovich Kryukov 15-Oct-12 13:41pm

Problem is not clear; please explain what's wrong.
--SA

Sergey Alexandrovich Kryukov 15-Oct-12 13:47pm

But after a second look, I can see a problem. Please see my answer for a fix.
--SA

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Sergey Alexandrovich Kryukov · Accepted Answer · 2012-10-15T07:46:00

You should never call any methods/properties of the currently executing UI objects from the thread other then its associated UI thread.

Instead, you need to use the method Invoke or BeginInvoke of System.Windows.Threading.Dispatcher (for both Forms or WPF) or System.Windows.Forms.Control (Forms only).

You will find detailed explanation of how it works and code samples in my past answers:
Control.Invoke() vs. Control.BeginInvoke()[^],
Problem with Treeview Scanner And MD5[^].

See also more references on threading:
How to get a keydown event to operate on a different thread in vb.net[^],
Control events not firing after enable disable + multithreading[^].

Besides, I don't recommend using asynchronous APIs, as direct use of threading is more straightforward, simple, the logic is more linear; you got more control. Of course, you will need to use thread synchronization techniques (the less, the better, but you need to make sure your code is thread safe). But those thread synchronization techniques are always the same, while asynchronous code depends on particular APIs. I think that asynchronous APIs flourished when multithreading was not a commonplace as it is now.

—SA