ProgressBar in multi-threaded application - C# Discussion Boards

Re: Cannot focus treeNode in a panel

2-Sep-08 4:23

How about setting SelectedNode?

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Kim06182-Sep-08 16:06

Kim0618

2-Sep-08 16:06

No, setting its the selectedNode and Focus() still cannot get it focused.

ProgressBar in multi-threaded application

Lutosław2-Sep-08 4:03

2-Sep-08 4:03

How to report a calculations' progress using a ProgressBar in a WinForms multi-threaded application? I want to utilize CPUs as much as I can and so use all (four) cores. After some googling the only thing I found is a suggestion to use a BackgroudWorker, but it supports only one thread for the same work.
The code looks like this:

Parallel.For(0, width, delegate(int x)
{
//for (int x = 0; x < width; x++)
//{
//calculations with two more nested loops.
(***)
    //}
});

At (***) I tried the following:
1.)

progress.Value = x;

This thrown an exception of course.
2.)

progress.BeginInvoke(new Action (delegate {
            progress.Value = x;
        }));

Here the ProgressBar was updated after all calculation were finished. Tried to set a number of threads to 3 but it didn't change anything.
The implemetation of the Parallel class is robust imho.

Any help appreciated.

Greetings - Gajatko

Portable.NET is part of DotGNU, a project to build a complete Free Software replacement for .NET - a system that truly belongs to the developers.

TheFM2342-Sep-08 4:18

TheFM234

2-Sep-08 4:18

There is a method that background workers have that is called "ReportProgress", and a event called "ProgressChanged" that triggers when the ReportProgress method is called. You can access the ProgressChanged from the original thread, unlike trying to directly access the progress bar via progressbar.value = x.

leppie2-Sep-08 4:24

2-Sep-08 4:24

gajatko wrote:
progress.BeginInvoke

Do not use BeginInvoke, as that will queue the invocation. Invoke should be sufficient.

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Lutosław2-Sep-08 6:12

2-Sep-08 6:12

Application hangs when using Invoke instead of BeginInvoke. From debugger, it stops on call to the Invoke method.

Greetings - Gajatko

Portable.NET is part of DotGNU, a project to build a complete Free Software replacement for .NET - a system that truly belongs to the developers.

#realJSOP2-Sep-08 5:05

#realJSOP

2-Sep-08 5:05

You're making it harder than it has to be.

Use a BackgroundWorker object to perform the calculation, and call the UpdateProgress method at the desired interval.

private BackgroundWorker myWorker = BackgroundWorker();

//--------------------------------------------------------------------------------
/// <summary>
/// Initializes the background worker thread.
/// </summary>
private void InitEncryptWorker()
{
    myWorker.WorkerReportsProgress	= true;
    myWorker.WorkerSupportsCancellation = true;
    myWorker.DoWork                    += new System.ComponentModel.DoWorkEventHandler(myWorker_DoWork);
    myWorker.RunWorkerCompleted        += new System.ComponentModel.RunWorkerCompletedEventHandler(myWorker_RunWorkerCompleted);
    myWorker.ProgressChanged           += new System.ComponentModel.ProgressChangedEventHandler(myWorker_ProgressChanged);
}

//--------------------------------------------------------------------------------
public void myWorker_DoWork(Object sender, DoWorkEventArgs e)
{
    BackgroundWorker thisWorker = sender as BackgroundWorker;
    
    int progress = 0;
    for (int i = 0; i < 1000; i++)
    {
        if (!thisWork.CancellationPending)
        {
            // do some work here

            // and then report progress
            thisWorker.ReportProgress(progress);
        }
    }
}

//--------------------------------------------------------------------------------
private void myWorker_ProgressChanged(object sender,ProgressChangedEventArgs e)
{
    if (e.ProgressPercentage != this.progressBar.Value)
    {
        this.progressBar.Value = e.ProgressPercentage;
    }
}


//--------------------------------------------------------------------------------
private void myWorker_RunWorkerCompleted(object sender,RunWorkerCompletedEventArgs e)
{
}

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-----
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Lutosław2-Sep-08 6:09

2-Sep-08 6:09

This way you use only one thread for calculations and utilize 25% of quad core processors

Greetings - Gajatko

Portable.NET is part of DotGNU, a project to build a complete Free Software replacement for .NET - a system that truly belongs to the developers.

#realJSOP2-Sep-08 7:43

#realJSOP

2-Sep-08 7:43

C'mon, be a programmer. If your calculations take so long that it's bothersome, put some Thread.Sleep(10) calls in the loop somewhere.

Mark Salsbery2-Sep-08 7:56

Mark Salsbery

2-Sep-08 7:56

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Lutosław2-Sep-08 9:09

2-Sep-08 9:09

John Simmons / outlaw programmer wrote:
C'mon, be a programmer

Yeach and then post your code on a Coding Horrors forum before someone else does. Laugh | :laugh:

Greetings - Gajatko

Portable.NET is part of DotGNU, a project to build a complete Free Software replacement for .NET - a system that truly belongs to the developers.

#realJSOP2-Sep-08 9:58

#realJSOP

2-Sep-08 9:58

Yeah, I'll do that. In the meantime, you'll still be dickin' around with your code, and I will have finished this particular task moved on to something else.

On the other hand, maybe using 25% of the CPU ain't so bad, after all. Of course, we can't determine the trade-offs because you haven't given us all the requirements.

Daniel Grunwald2-Sep-08 6:22

Daniel Grunwald

2-Sep-08 6:22

Parallel.For does not run the calculation in the background. It just splits the work to multiple threads, but the UI is blocked until the calculation has finished.
If you want multiple threads to calculate in the background, use BackgroundWorker+Parallel.For.

Lutosław2-Sep-08 6:29

2-Sep-08 6:29

Frankly speaking I use my own implementation of Parallel to preserve .Net 2.0 compatibility but it works as you said, too. I will check if it works and post soon.

Greetings - Gajatko

Portable.NET is part of DotGNU, a project to build a complete Free Software replacement for .NET - a system that truly belongs to the developers.

Lutosław2-Sep-08 9:33

2-Sep-08 9:33

BackgroundWorker+Parallel.For combination doesn't work.

progress.Value = e.ProgressPercentage;

throws an exception (Cross-thread operation not valid: Control 'progress' blah blah blah)

and

progress.Invoke(new Action(delegate {
progress.Value = e.ProgressPercentage;
}));

hangs the program. Any ideas? I though that this situation is so common that there is at least one satisfactory solution for it... Frown | :(

Greetings - Gajatko

Portable.NET is part of DotGNU, a project to build a complete Free Software replacement for .NET - a system that truly belongs to the developers.

Daniel Grunwald2-Sep-08 9:38

Daniel Grunwald

2-Sep-08 9:38

Why is it hanging?
Take a look at what the threads are doing.

Why is the main thread blocked? What is it waiting for? Maybe you have a dead lock? (progress.Invoke waits for the main thread to finish any active event handlers, maybe the main thread is somehow still waiting for your calculation?)

ellllllllie2-Sep-08 3:07

ellllllllie

2-Sep-08 3:07

Hello,
this is my code to retrieve the DeviceId of a windows mobile 5.0
[DllImport("coredll.dll")]
private static extern int GetDeviceUniqueID([In, Out] byte[] appdata, int cbApplictionData,
int dwDeviceIDVersion,
[In, Out] byte[] deviceIDOuput, ref uint pcbDeviceIDOutput);

private static string s_UniqueDeviceID;
public static string GetUniqueDeviceID()
{
if (string.IsNullOrEmpty(s_UniqueDeviceID))
{
// define AppString
string AppString = "MyAppString";

// get the byte array for the string
byte[] AppData = Encoding.ASCII.GetBytes(AppString);

// some parameters for the native call
int appDataSize = AppData.Length;
uint SizeOut = 20;

// our out parameter
byte[] DeviceOutput = new byte[20];

// Call the native GetDeviceUniqueID method from coredll.dll
GetDeviceUniqueID(AppData, appDataSize, 1, DeviceOutput, ref SizeOut);

// check that we got something
if (SizeOut > 0)
{
// build text from received bytes
StringBuilder resultText = new StringBuilder();
for (int i = 0; i < DeviceOutput.Length; i++)
{
resultText.Append(string.Format("{0:x2}", DeviceOutput));
}

// set up result
s_UniqueDeviceID = resultText.ToString();
}
}

return s_UniqueDeviceID;
}
}

The GetDeviceUniqueId() raise an error of type Cannot find an entry point .

Do someone can help me.

Best regards

dghdfghdfghdfghdgh

Re: ID

Manas Bhardwaj2-Sep-08 3:36

Manas Bhardwaj

2-Sep-08 3:36

Wow!!! you get the most absurd question of the day award...
First, you didnt even have time to write your subject/question in detail.
Second, instead you posted your code completely (without explanataion) to make us guess.
Third, this is not Mobile Dev Forum...better look in Mobile Development[^]

Please remember to rate helpful or unhelpful answers, it lets us and people reading the forums know if our answers are any good.

Re: ID

leppie2-Sep-08 3:45

2-Sep-08 3:45

It's a pinvoke question on C#. Not really offtopic.

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Re: ID

leppie2-Sep-08 3:43