How to Kill the Worker Thread ?

Suresh H

Hello Everyone, I have Demo MFC application, with 2 buttons Start and End Button. Start button will start 2 threads

void CThreadDemoDlg::OnStart()
{
// TODO: Add your control notification handler code here

HANDLE hr1,hr2;
hr1 = CreateThread(NULL,0,(unsigned long (\_\_stdcall \*)(void \*))WorkerThreadOne,this,0,0);
hr2 = CreateThread(NULL,0,(unsigned long (\_\_stdcall \*)(void \*))WorkerThreadTwo,this,0,0);

}

UINT WorkerThreadOne(LPVOID Param)
{
fstream OutFile;
OutFile.open("FileOne.txt",ios::out);

for(int i=0;i<10000;i++)
	OutFile  << i << " ";
OutFile.close();
return true;

}

Can anyone please tell me how to kill the thread ? OnEnd click. Thanking you, Suresh.

Rajesh R Subramanian

First of all, you must use AfxBeginThread, if you're using MFC[^].

void CThreadDemoDlg::OnEnd(){
SetEvent(hEndAllEvent);
}

UINT WorkerThreadXYZ(LPVOID pParams){

fstream OutFile;
OutFile.open("FileOne.txt",ios::out);

for(int i=0;i<10000;i++)
{
if(WaitForSingleObject(hEndAllEvent, 0) == WAIT_OBJECT_0) break;
OutFile << i << " ";
}

OutFile.close();
return FALSE; //Return false while using CWinThread, unless you know what you're doing, or unless you like memory leaks.
}

Have a look at WaitForSingleObject[^]

It is a crappy thing, but it's life -^ Carlo Pallini

ParagPatel

Hi, You can delete thread , using TerminateThread usage: TerminateThread()[^] Note: it will not free your Thread Local memory.

Parag Patel

Hamid Taebi

You can forget Terminate*(TerminateThread/TerminateProcess). MSDN: TerminateThread is a dangerous function. Use it only in the most extreme cases. Why 1.00/5 ???

Of one Essence is the human race thus has Creation put the base One Limb impacted is sufficient For all Others to feel the Mace (Saadi )

modified on Tuesday, April 14, 2009 5:54 AM

Hamid Taebi

Did you see bottom of CreateThread on the MSDN it explains it for you.

Of one Essence is the human race thus has Creation put the base One Limb impacted is sufficient For all Others to feel the Mace (Saadi )

Cedric Moonen

X| That's probably one of the worst way to do that. You should never call TerminateThread (unless in very specific conditions). In general, there are much better ways to achieve what you want.

Cédric Moonen Software developer
Charting control [v1.5] OpenGL game tutorial in C++

Suresh H

Hi Parag Patel, Thanks for the reply. I tried with this below code but still the thread is running its not terminated, can u please tell how to kill the thread.

void CThreadDemoDlg::OnEnd()
{
// TODO: Add your control notification handler code here

TerminateThread(hr1,1);
TerminateThread(hr2,1);

}

Rajesh R Subramanian

Having looked at your code in your first post, I can tell you that you MUST NOT use TerminateThread(). It's saddening to see you've picked the worst suggestion that was given to you.

It is a crappy thing, but it's life -^ Carlo Pallini

Cedric Moonen

Maybe you didn't see the replies to his post but it is strongly recommanded not to use TerminateThread. A better approach would be to pass a pointer to your dialog class to the thread function, and within the thread cast it back to your dialog and call a public function on it. Inside that function you put the code you already provided except that in your loop, you also check if a flag is set or not (this flag is a simple bool which is a member of the dialog). If the flag is set, you simply stop the loop and the function terminates. When you click on the end button, you can simply set this flag so that the loop stops.

Cédric Moonen Software developer
Charting control [v1.5] OpenGL game tutorial in C++

Cedric Moonen

Rajesh R Subramanian wrote:

It's saddening to see you've picked the worst suggestion that was given to you.

That's usually the case because it looks like the easiest solution :sigh:

Cédric Moonen Software developer
Charting control [v1.5] OpenGL game tutorial in C++

Suresh H

Hello Everyone,, Sorry saw all yr response now.Thanks a lot for the reply. I am very much new to the Thread Concept. thought of learning the basics of threads. can anyone suggest me some nice Article to start with. Thanking you, Suresh

ParagPatel

Can you paste your code snap here? You can also use flag mechanism, its good solution.

//globle variable
HANDLE hr1,hr2;
bool stopTh; //default set to false.

void CThreadDemoDlg::OnStart()
{
// TODO: Add your control notification handler code here

stopTh = false;

hr1 = CreateThread(NULL,0,(unsigned long (\_\_stdcall \*)(void \*))WorkerThreadOne,this,0,0);
hr2 = CreateThread(NULL,0,(unsigned long (\_\_stdcall \*)(void \*))WorkerThreadTwo,this,0,0);

}
void CThreadDemoDlg::OnEnd()
{
// TODO: Add your control notification handler code here

stopTh = true;

}

UINT WorkerThreadOne(LPVOID Param)
{
fstream OutFile;
OutFile.open("FileOne.txt",ios::out);

for(int i=0;i<10000;i++)
{
	if(stopTh == true)
		break;
	OutFile  << i << " ";
}
OutFile.close();
return true;

}

Why 1.0/5.0?

Parag Patel

modified on Thursday, April 16, 2009 9:40 AM

Suresh H

Hello Cédric Moonen,, Sorry saw yr response now.Thanks a lot for the reply. I am very much new to the Thread Concept. thought of learning the basics of threads. can anyone suggest me some nice basic Article to start with. Thanking you, Suresh

Cedric Moonen

This[^] article is one of the best I know of.

Cédric Moonen Software developer
Charting control [v1.5] OpenGL game tutorial in C++

Rajesh R Subramanian

There are plenty of articles around, but before all that, do you have a book on MFC programming? If not, please buy one. My book recommendations for MFC are here[^] Essay recommendation: Worker Threads[^] UI Threads[^] There are plenty of articles at CP as well, just do a search.

It is a crappy thing, but it's life -^ Carlo Pallini

Rajesh R Subramanian

It looks like we both gave him the same article to read, at the same time (20 mins back, as of now). :)

It is a crappy thing, but it's life -^ Carlo Pallini

Cedric Moonen

It seems that somebody is voting 1 to all of our messages. Can you guess who it is ? :rolleyes:

Cédric Moonen Software developer
Charting control [v1.5] OpenGL game tutorial in C++

Rajesh R Subramanian

I know, but I'm ignoring that. I've been balancing the votes. Forget it, the votes will be balanced by the regulars. :)

It is a crappy thing, but it's life -^ Carlo Pallini

David Crow

Suresh H wrote:

for(int i=0;i<10000;i++)

You need to add another condition to this loop, something like:

CEvent m_event; // start as non-signaled

for (int i = 0; i < 10000; i++)
{
// set the event to signaled when the End button is clicked
if (WaitForSingleObject(m_event.m_hObject, 0) == WAIT_OBJECT_0)
break;
}

"Old age is like a bank account. You withdraw later in life what you have deposited along the way." - Unknown

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

David Crow · modified on Thursday, April 16, 2009 9:40 AM

ParagPatel wrote:

if(stopTh == true)

Unless stopTh is volatile, the compiler will optimize out this check.

"Old age is like a bank account. You withdraw later in life what you have deposited along the way." - Unknown

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons