CODEWITHSUNDEEP
c#winformsmultithreading
Mobin
Mobin

Reputation: 4920

How to kill a thread instantly in C#?

I am using the thread.Abort method to kill the thread, but it not working. Is there any other way of terminating the thread?

private void button1_Click(object sender, EventArgs e)
{
    if (Receiver.IsAlive == true)
    {
        MessageBox.Show("Alive");
        Receiver.Abort();
    }
    else
    {
        MessageBox.Show("Dead");
        Receiver.Start();
    }
}

I am using this but every time I get the Alive status, Receiver is my global thread.

Upvotes: 52

Views: 237289

Answers (5)

Wael Dalloul
Wael Dalloul

Reputation: 23044

Thread will be killed when it finishes its work, so if you are using loops or something, you should pass variable to the thread to stop the loop. After that, the thread will be finished.

Upvotes: 9

Adrian Regan
Adrian Regan

Reputation: 2250

You should first have some agreed method of ending the thread. For example a running_ valiable that the thread can check and comply with.

Your main thread code should be wrapped in an exception block that catches both ThreadInterruptException and ThreadAbortException that will cleanly tidy up the thread on exit.

In the case of ThreadInterruptException you can check the running_ variable to see if you should continue. In the case of the ThreadAbortException you should tidy up immediately and exit the thread procedure.

The code that tries to stop the thread should do the following:

running_ = false;
threadInstance_.Interrupt();
if(!threadInstance_.Join(2000)) { // or an agreed resonable time
   threadInstance_.Abort();
}

Upvotes: 24

Nickon
Nickon

Reputation: 10156

You can kill instantly doing it in that way:

private Thread _myThread = new Thread(SomeThreadMethod);

private void SomeThreadMethod()
{
   // do whatever you want
}

[SecurityPermissionAttribute(SecurityAction.Demand, ControlThread = true)]
private void KillTheThread()
{
   _myThread.Abort();
}

I always use it and works for me:)

Upvotes: 34

Sesh
Sesh

Reputation: 6192

C# Thread.Abort is NOT guaranteed to abort the thread instantaneously. It will probably work when a thread calls Abort on itself but not when a thread calls on another.

Please refer to the documentation: http://msdn.microsoft.com/en-us/library/ty8d3wta.aspx

I have faced this problem writing tools that interact with hardware - you want immediate stop but it is not guaranteed. I typically use some flags or other such logic to prevent execution of parts of code running on a thread (and which I do not want to be executed on abort - tricky).

Upvotes: 6

redtuna
redtuna

Reputation: 4600

The reason it's hard to just kill a thread is because the language designers want to avoid the following problem: your thread takes a lock, and then you kill it before it can release it. Now anyone who needs that lock will get stuck.

What you have to do is use some global variable to tell the thread to stop. You have to manually, in your thread code, check that global variable and return if you see it indicates you should stop.

Upvotes: 76

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