Question

I have written a thread which I’ve started using the start method but I’m not able to know when the thread has done executing the method and destroy the thread object.

_ProgressThread = New Thread(AddressOf ExecProc)
_ProgressThread.IsBackground = False
_ProgressThread.Start()

//the flow of execution should come here only after the thread has executed the method
//but its coming and executing this line after the thread has started.
 Me.MainInit()
_ProgressThread = Nothing

What is the best method. Please help. Also I want to call a method after the thread has done executing the method.

Answer 1

There are two (or more) possible ways. One is to use a ManualResetEvent as follows:

_Event = New ManualResetEvent(False); <-- Create event globally

Then, in your thread’s start code:

_ProgressThread = New Thread(AddressOf ExecProc)
_ProgressThread.IsBackground = False
_ProgressThread.Start()

//the flow of execution should come here only after the thread has executed the method
//but its coming and executing this line after the thread has started.
_Event.WaitOne(); <-- This waits!
_Event.Close();   <-- This closes the event

Me.MainInit()
_ProgressThread = Nothing

In your thread method, you must call _Event.Set() before the method returns in all cases, otherwise your application will be blocked.

Another way would be to have to thread invoke a delegate when finished. The code that you want to execute after the thread is done (Me.MainInit()) would then go into the delegate method. This is actually quite elegant.

For example:

public delegate void ThreadDoneDelegate();

private void ExecProc()
{
    ThreadDoneDelegate del = new ThreadDoneDelegate(TheThreadIsDone);

    ... // Do work here

    this.Invoke(del);
}

private void TheThreadIsDone()
{
    ... // Continue with your work
}

Sorry, I do not speek VB fluently, so you’ll have to convert this little C# snippet 🙂