WPF任务管理器：处理刷新的CPU负载值？

Question

I am currently somewhat new to c#/wpf (and coding in general). I decided to start another project, being a custom made "task manager" of sorts.

(While I use binding, this is NOT a MVVM project, so all answers welcome)

If you have ever opened task manager, you know that one of the main helpful tools it provides is a updating view of CPU/RAM/Whatever usage. Telling the user what percent of the resource they are using.

My problem is not getting the CPU percentage. I am unsure on how to refresh the text property for CPU load in the UI efficiently.

My first thought was that I should create a Background worker (which is probably correct) to separate the thread loads. However, I can't seem to wrap my mind on the solution to implement the background workers in a useful way.

The code is currently set up in this fashion:

1. When page is loaded, public BgWrk creates a new instance of it self.
2. Adds task to be called when ran.
3. BgWrk is ran.
4. New instance of method to be called is made.
5. Dispatcher is invoked on main thread to update UI.
6. Invoke consists of setting public string PerCpu (bound in other class, using INotifyPropertyChanged & all) on the return value of "grabber"'s CpuPerUsed.
7. BgWrk disposed.

8. Program loops (this is most likely the problem).

    private void Grid_Loaded(object sender, RoutedEventArgs e) { BgWrk = new BackgroundWorker(); BgWrk.DoWork += new DoWorkEventHandler(BackgroundWorker1_DoWork); BgWrk.RunWorkerAsync(); } private void BackgroundWorker1_DoWork(object sender, DoWorkEventArgs e) { while (true) { CpuInfoGrabber grabber = new CpuInfoGrabber(); Application.Current.Dispatcher.Invoke(new Action (() => Bnd.PerCpu = grabber.CpuPerUsed())); BgWrk.Dispose(); } } 

Again the code works, but it is WAY to slow due to the load of retrieving all of that data. Any suggestions on how to make this work well are appreciated!

Thanks

Answer 1

Instead of looping you could use a timer to periodically poll for the CPU usage.

class Test
{
    private System.Timers.Timer _timer;

    public Test( )
    {
        _timer = new System.Timers.Timer
        {
            // Interval set to 1 millisecond.
            Interval = 1,
            AutoReset = true,                
        };
        _timer.Elapsed += _timer_Elapsed;
        _timer.Enabled = true;
        _timer.Start( );
    }

    private void _timer_Elapsed( object sender, System.Timers.ElapsedEventArgs e )
    {
        // This handler is not executed on the gui thread so
        // you'll have to marshal the call to the gui thread
        // and then update your property.
       var grabber = new CpuInfoGrabber();
       var data = grabber.CpuPerUsed();
       Application.Current.Dispatcher.Invoke( ( ) => Bnd.PerCpu = data );
    }
}

Answer 2

I'd use Task.Run instead of a BackgroundWorker in your case:

private void Grid_Loaded(object sender, RoutedEventArgs e)
{
    //Keep it running for 5 minutes
    CancellationTokenSource cts = new CancellationTokenSource(new TimeSpan(hours: 0, minutes: 5, seconds: 0));

    //Keep it running until user closes the app
    //CancellationTokenSource cts = new CancellationTokenSource();

    //Go to a different thread
    Task.Run(() =>
    {
        //Some dummy variable
        long millisecondsSlept = 0;

        //Make sure cancellation not requested
        while (!cts.Token.IsCancellationRequested)
        {
            //Some heavy operation here
            Thread.Sleep(500);
            millisecondsSlept += 500;

            //Update UI with the results of the heavy operation
            Application.Current.Dispatcher.Invoke(() => txtCpu.Text = millisecondsSlept.ToString());
        }
    }, cts.Token);
}