Timer Thread does not get disposed

[Dipankar]

In an Windows application I have created a Timer to monitor some
WorkerThread's state. Once the worker thread stops the timer should
also dispose after displaying the message that Worker Thread is done.

// Instance variables
private Thread workerThread = null;
private System.Threading.Timer workerThreadMonitorTimer = null;

/// Code inside a button click event
ThreadStart workerThreadStart = new ThreadStart(DoWork);
this.workerThread = new Thread(migrationProcessStart);
this.workerThread.Start();

TimerCallback timerCallBack = new TimerCallback(CheckWorkerThread);
this.workerThreadMonitorTimer = new
System.Threading.Timer(timerCallBack);
this.workerThreadMonitorTimer.Change(0, 5000);

In the CheckWorkerThread method I wrote:

if (this.workerThread.ThreadState ==
System.Threading.ThreadState.Stopped)
{
// Display some message
this.workerThreadMonitorTimer.Dispose();
}

But the timer does not get disposed. It still executes the
CheckWorkerThread method next time as well. So message is getting
displayed multiple times. Its not even ending.

 

[Ignacio Machin \( .NET/ C# MVP \)]

Hi,

In an Windows application I have created a Timer to monitor some
WorkerThread's state. Once the worker thread stops the timer should
also dispose after displaying the message that Worker Thread is done.

// Instance variables
private Thread workerThread = null;
private System.Threading.Timer workerThreadMonitorTimer = null;

In a win app you better use System.Windows.Forms.Timer class.

/// Code inside a button click event
ThreadStart workerThreadStart = new ThreadStart(DoWork);
this.workerThread = new Thread(migrationProcessStart);
this.workerThread.Start();

TimerCallback timerCallBack = new TimerCallback(CheckWorkerThread);
this.workerThreadMonitorTimer = new
System.Threading.Timer(timerCallBack);
this.workerThreadMonitorTimer.Change(0, 5000);

Do you want to call it right away? otherwise call it like Change( 5000,
5000)

In the CheckWorkerThread method I wrote:

if (this.workerThread.ThreadState ==
System.Threading.ThreadState.Stopped)

You should also first check if workerThread is null , just as a way to avoid
a nullreference exception

{
// Display some message
this.workerThreadMonitorTimer.Dispose();
}

You should call :
Change( Timeout.Infinite, Timeout.Infinite );
this.workerThreadMonitorTimer.Dispose();
this.workerThreadMonitorTimer = null;

 

[Dipankar]

Hi,

What is the specific reason of using Forms.Timer rather than
Threading.Timer?
Do these two classes bahave differently?

Cheers!!
Dipankar