Problem in Wait for a thread to finish in C #

Question

3.50/5 (2 votes)

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Hi All,

I am developing a application in WPF and C#.

I am using a thread to accomplished an opration.
The operation takes few second to finish.
The problem is that when the thread is on process my window (e.g. user interface) become Inactive even in Task Manager's Application tab the application status become Not Responding until the thread is finish.
After finishing, the user interface become normal.

So i want that...
Once a thread is started,it shouldn't be blocking the UI and also wait to finish the thread.

I try all in below.

Try 1 using Sleep :

C#

Thread th1 = new Thread(operation1);
th1.Start();
Thread.Sleep(5000);

Try 2 using Join:

C#

Thread th1 = new Thread(operation1);
th1.Start();
Thread.Join();

Try 3 using AutoResetEvent :

C#

static EventWaitHandle _waitHandle = new AutoResetEvent (false);
Thread th1 = new Thread(operation1);
th1.Start();
_waitHandle.WaitOne();

private void operation1()
       {
           // do the operation

           _waitHandle.Set();
       }

Posted 15-Mar-11 22:33pm

sufi2008123

Updated 16-Mar-11 23:50pm

v4

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Comments

Dalek Dave 16-Mar-11 4:50am

Edited for Readability.

5 solutions

Solution 5

When you use .join to wait until all the yarn and the next instruction is
But the string .sleep where he holds the time that you specified
So you must like the 2010 visual studio version of semaphore can use instead of sleep
And cause failure of your application processor allocation is wrong

C#

class Program
    {
        static SemaphoreSlim sem1 = new SemaphoreSlim(1);
        static SemaphoreSlim sem2 = new SemaphoreSlim(0);
        
        static void Main()
        {
            Thread t1 = new Thread(f1);
            Thread t2 = new Thread(f2);
            t1.Start();
            t2.Start();
            t1.Join();
            t2.Join();
            Console.Read();
        }

        static void f1()
        {
            for (int i = 1; i <= 100; i++)
            {
                sem1.Wait();
                Console.WriteLine("Hello");
                sem2.Release();
            }
        }

        static void f2()
        {
            for (int i = 1; i <= 100; i++)
            {
                sem2.Wait();
                Console.WriteLine("Bye");
                sem1.Release();
            }
        }
    }

Posted 11-Apr-11 5:32am

esmailian

Updated 11-Apr-11 21:13pm

v3

Comments

BobJanova 12-Apr-11 5:48am

Is this not a guaranteed deadlock?

esmailian 13-Apr-11 13:36pm

Yes, it guarantees that the source of the hello and bye to print

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Sergey Alexandrovich Kryukov · Accepted Answer · 2011-03-15T22:49:00

Solution 1

If you use Thread.Join in UI thread, you screw it up exactly you if you did not create any thread and did it in UI thread in first place. This call is the blocking one. It looks like you're seriously confused about threads.

There is a number of good patterns. I have a collection of my past Answers on the topic here: How to get a keydown event to operate on a different thread in vb.net[^], see other Answers, show more of your code and ask follow-up Questions.

—SA

Posted 15-Mar-11 22:49pm

Sergey Alexandrovich Kryukov

Comments

Olivier Levrey 16-Mar-11 7:24am

I agree. Voted 5.

Sergey Alexandrovich Kryukov 16-Mar-11 12:12pm

Thank you.
--SA

Espen Harlinn 16-Mar-11 16:54pm

I'll join in with my 5

Sergey Alexandrovich Kryukov 16-Mar-11 17:14pm

Thanks for joining our party :-)
--SA

Albin Abel 17-Mar-11 0:16am

My 5

Sergey Alexandrovich Kryukov 17-Mar-11 0:48am

Thank you very much.
--SA

Olivier Levrey · Accepted Answer · 2011-03-16T01:26:00

Solution 2

SA is right. Using Join or WaitOne or Sleep will block your application. If you want to wait for the thread to finish then it means you don't need a thread.

If you want to wait and show its progress to the user, then maybe this will be useful:
ProgressForm: a simple form linked to a BackgroundWorker[^]

Posted 16-Mar-11 1:26am

Olivier Levrey

Comments

Sergey Alexandrovich Kryukov 16-Mar-11 12:13pm

That's all correct, my 5, only we don't know what OP really wants, so further instructions should be done if OP posts a follow-up Question.
--SA

Espen Harlinn 16-Mar-11 16:57pm

Nice link Olivier - that's one way to get a 10 :)

Albin Abel 17-Mar-11 0:17am

My 5

Olivier Levrey 17-Mar-11 5:00am

Thank you guys :)

#realJSOP · Accepted Answer · 2011-03-16T01:53:00

Solution 3

What do you WANT to happen? Once a thread is started, it shouldn't be blocking the UI.

C#

public void button_Click(...)
{
    Thread thread = new Thread(new ThreadStart(ThreadProc));
    thread.Start();
}

public void ThreadStart()
{
   // do something
}

Even if you use a BackgroundWorker objec, it should run without blocking the UI.

If you need the thread to update the UI as it's running, that's simple ennough.

BTW, your first example is going to start the thread, and then sleep the UI for 5 seconds.

Further, why use a thread if you're going to use Join? You should use Join to couple threads together so that one thread doesn't finish until the joined thread is also finished.

It looks like you don't have a firm grasp of how threading works in .Net.

Posted 16-Mar-11 1:53am

#realJSOP

Comments

Sergey Alexandrovich Kryukov 16-Mar-11 12:14pm

Sure, my 5. That's the thing: who knows what OP wanted?
--SA

sufi2008123 17-Mar-11 5:47am

thanks to all

I Want

Once a thread is started,it shouldn't be blocking the UI and also wait to finish the thread.

Sergey Alexandrovich Kryukov 17-Mar-11 13:04pm

You should not wait for the finish of the thread. This is very rare (unless it is a very end of application lifetime, where you may or may not need to wait). The robust patters look like this, the thread spawn works independently but sends notifications to the UI thread via Invoke or BeginInvoke (method of Dispatcher or System.Windows.Forms.Control).
--SA

Albin Abel 17-Mar-11 0:17am

My 5

Sergey Alexandrovich Kryukov 17-Mar-11 13:01pm

Thank you, Albin.
--SA

Espen Harlinn · Accepted Answer · 2011-03-16T10:51:00

Solution 4

You may find Sacha Barbers articles interesting:
Beginners Guide to Threading in .NET: Part 1 of n[^]
Beginner's Guide to Threading in .NET: Part 2 of n[^]
Beginner's Guide to Threading in .NET: Part 3 of n[^]
Beginners Guide to Threading in .NET: Part 4 of n[^]
Beginners Guide to Threading in .NET: Part 5 of n[^]

In Task Parallel Library: 1 of n[^] he shows how to use the DispatcherSynchronizationContext[^] - it offers an elegant solution on how to interoperate with the UI thread.

Best regards
Espen Harlinn

Posted 16-Mar-11 10:51am

Espen Harlinn

Comments

Sergey Alexandrovich Kryukov 16-Mar-11 17:19pm

Wow! I'm familiar this this series, good to know, so 5.
--SA

Espen Harlinn 16-Mar-11 17:23pm

Thank you, SAKryukov!

Albin Abel 17-Mar-11 0:18am

Good Series. my 5

Espen Harlinn 17-Mar-11 9:42am

Thank you, AlbinAbel!