WinForm Multithreading. Use backgroundWorker or not? - c#

I have a simple app which fires of a series of data intensive tasks. I'm not very experienced with WinForms and I was wondering the best way to do this without locking the interface. Can backgroundWorker be re-used, or is there another way to do this?
Thanks

BackgroundWorker is a thread that also includes notification synchronization. For example, if you wanted to update your UI when the scan completes, a regular Thread cannot access the UI objects (only the UI thread can do that); so, BackgroundWorker provides a Completed event handler that runs on the UI thread when the operation completes.
for more info see: Walkthrough: Multithreading with the BackgroundWorker Component (MSDN)
and a simple sample code:
var worker = new System.ComponentModel.BackgroundWorker();
worker.DoWork += (sender,e) => Thread.Sleep(60000);
worker.RunWorkerCompleted += (sender,e) => MessageBox.Show("Hello there!");
worker.RunWorkerAsync();

backgroundWorker can be used.
its benefit - it allows you to update a progress bar and interact with UI controls. (WorkerReportsProgress)
Also it has a cancellation mechanism. (WorkerSupportsCancellation)

You can use BackgroundWorker for such requirements. Below is a sample which updates a label status based on percentage task [long running] completion. Also, there is a sample business class which sets some value and the value is set back to UI via ProgressChanged handler. DoWork is the place where you write your long running task logic. Copy-Paste the code below after adding a label and backgroundworker component on a Winforms app & give it a shot. You may debug across various handler [RunWorkerCompleted, ProgressChanged, DoWork] and have a look at InitWorker method. Notice the cancellation feature too.
using System.ComponentModel;
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
public partial class Form3 : Form
{
private BackgroundWorker _worker;
BusinessClass _biz = new BusinessClass();
public Form3()
{
InitializeComponent();
InitWorker();
}
private void InitWorker()
{
if (_worker != null)
{
_worker.Dispose();
}
_worker = new BackgroundWorker
{
WorkerReportsProgress = true,
WorkerSupportsCancellation = true
};
_worker.DoWork += DoWork;
_worker.RunWorkerCompleted += RunWorkerCompleted;
_worker.ProgressChanged += ProgressChanged;
_worker.RunWorkerAsync();
}
void DoWork(object sender, DoWorkEventArgs e)
{
int highestPercentageReached = 0;
if (_worker.CancellationPending)
{
e.Cancel = true;
}
else
{
double i = 0.0d;
int junk = 0;
for (i = 0; i <= 199990000; i++)
{
int result = _biz.MyFunction(junk);
junk++;
// Report progress as a percentage of the total task.
var percentComplete = (int)(i / 199990000 * 100);
if (percentComplete > highestPercentageReached)
{
highestPercentageReached = percentComplete;
// note I can pass the business class result also and display the same in the LABEL
_worker.ReportProgress(percentComplete, result);
_worker.CancelAsync();
}
}
}
}
void RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
if (e.Cancelled)
{
// Display some message to the user that task has been
// cancelled
}
else if (e.Error != null)
{
// Do something with the error
}
}
void ProgressChanged(object sender, ProgressChangedEventArgs e)
{
label1.Text = string.Format("Result {0}: Percent {1}",e.UserState, e.ProgressPercentage);
}
}
public class BusinessClass
{
public int MyFunction(int input)
{
return input+10;
}
}
}

The background worker would be a good choice to start with
For more info look here
http://msdn.microsoft.com/en-us/library/system.componentmodel.backgroundworker.aspx

Related

Two issues with backgroundworker with progress bar WPF

I'm using WPF and I have main thread which is GUI (wizard).
When user click Finish on wizard it open second thread which display user progress bar used in background worker.
In Main thread I doing:
MessageWithProgressBar progress = new MessageWithProgressBar();
progress.Show();
createFilesInA();
createFilesInB();
createFilesInC();
createFilesInD();
createFilesInE();
createFilesInF();
createFilesInG();
createFilesInH();
createFilesInI();
createFilesInJ();
createFilesInK();
In each createFiles method I increment by 1 the static variable called currentStep which I used it in background worker as detailed below.
In background worker I doing:
public partial class MessageWithProgressBar : Window
{
private BackgroundWorker backgroundWorker = new BackgroundWorker();
public MessageWithProgressBar()
{
InitializeComponent();
backgroundWorker.WorkerReportsProgress = true;
backgroundWorker.ProgressChanged += ProgressChanged;
backgroundWorker.DoWork += DoWork;
backgroundWorker.RunWorkerCompleted += BackgroundWorker_RunWorkerCompleted;
}
private void DoWork(object sender, DoWorkEventArgs e)
{
Thread.Sleep(100);
int i = GeneralProperties.General.currentStep;
if (i > GeneralProperties.General.thresholdStep)
{
progress.Dispatcher.BeginInvoke(DispatcherPriority.Normal,
new DispatcherOperationCallback(delegate
{
progress.Value = 100;
title.Content = progress.Value.ToString();
return null;
}), null);
return;
}
else
{
progress.Dispatcher.BeginInvoke(DispatcherPriority.Normal,
new DispatcherOperationCallback(delegate
{
progress.Value = (int)Math.Floor((decimal)(8 * i));
progressLabel.Text = progress.Value.ToString();
return null;
}), null);
}
}
private void ProgressChanged(object sender, ProgressChangedEventArgs e)
{
progress.Dispatcher.BeginInvoke(DispatcherPriority.Normal,
new DispatcherOperationCallback(delegate
{
progress.Value = e.ProgressPercentage;
return null;
}), null);
}
private void BackgroundWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
progress.Dispatcher.BeginInvoke(DispatcherPriority.Normal,
new DispatcherOperationCallback(delegate
{
progress.Value = 100;
title.Content = progress.Value.ToString();
return null;
}), null);
WindowMsgGenDB msg = new WindowMsgGenDB();
msg.Show();
}
private void Window_Loaded(object sender, RoutedEventArgs e)
{
if (backgroundWorker.IsBusy == false)
{
backgroundWorker.RunWorkerAsync();
}
}
}
The main thread updated variable called currentStep and the second thread used it to report on the main thread progress.
The operations of the main thread takes a few seconds (not more 15 seconds)
I have two issues:
I see on progress bar only when currentStep=2 (then the progress is 16) and then the progress is 100, and I don't see every step
At the beginning, the progress bar is freeze and it seems like it stuck.
(maybe it connects to the call progress.Show() from the main thread?)
Thanks!
As far as I understand your code your background worker is not doing anything, really. It updates the progress once and that's it.
Also: using global static variables to communicate between a form and a background worker - ouch...
Also, you're using it wrong in my opinion. The work (CreateFilesInA ... CreateFilesInK) should be done by the background worker - that's what it is for. As the main thread will be blocked the way you implemented it, you will not see any updates otherwise.
The usual way to implement something like this is:
Create progress window and disable UI
Start background worker that does stuff in DoWork. In DoWork, after every call to a CreateFilesInXYZ method, call ReportProgress to the the UI be updated.
Update stuff in progress window whenever ProgressChanged event is fired
Hide progress window and enable your application's UI when background worker is done
The way you're doing it it's in no way asynchronous. So, actually, your code should look something like this:
public partial class MainWindow : Window
{
private BackgroundWorker backgroundWorker = new BackgroundWorker();
private MessageWithProgressBar progressWindow;
public MainWindow()
{
InitializeComponent();
backgroundWorker.WorkerReportsProgress = true;
backgroundWorker.ProgressChanged += ProgressChanged;
backgroundWorker.DoWork += DoWork;
backgroundWorker.RunWorkerCompleted += BackgroundWorker_RunWorkerCompleted;
}
private void Window_Loaded(object sender, RoutedEventArgs e)
{
progressWindow = new MessageWithProgressBar();
progressWindow.Owner = this;
progressWindow.Show();
backgroundWorker.RunWorkerAsync();
}
private void DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = (BackgroundWorker)sender;
int numSteps = 11;
int currentStep = 0;
int progress = 0;
CreateFilesInA();
currentStep += 1;
progress = (int)((float)currentStep / (float)numSteps * 100.0);
worker.ReportProgress(progress);
CreateFilesInB();
currentStep += 1;
progress = (int)((float)currentStep / (float)numSteps * 100.0);
worker.ReportProgress(progress);
// All other steps here
...
}
private void ProgressChanged(object sender, ProgressChangedEventArgs e)
{
progressWindow.progress.Value = e.ProgressPercentage;
}
private void BackgroundWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
progressWindow.Close();
WindowMsgGenDB msg = new WindowMsgGenDB();
msg.Show();
}
}
Please note that the above code goes into your main window! The MessageWithProgressWindow does not contain any code. Maybe the Window_Loaded event handler is not the right place to start the background worker, but you get the picture.

C# BackgroundWorker not working as parameter

public static void CalculateAttributions(BackgroundWorker worker, string _filename, ComboBox cmb, OpenFileDialog open)
{
worker = new BackgroundWorker { WorkerReportsProgress = true };
while (wave.Position != length)
{
...Process..
worker.ReportProgress((100 * (int)(length / wave.Position)) / (int)(length / mainBuffer.Length));
}
}
I wrote this method in a class to perform my calculations and using BackgroundWorker as parameter to show a Progressbarduring loop. However when i run this method in Form.cs
private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
progressBar1.Value = Math.Min(e.ProgressPercentage, 100);
}
this event is not working so ProgressBar value not changed. How can i make it work?
The report Progress event you have given here is for the backgroundworker1 and not the worker you coded within the function CalculateAttributions(...)
To enbale report progress and do progress bar changes.. Try the following code
Worker1.ProgressChanged+=new delegate {
progressBar1.Value = Math.Min(e.ProgressPercentage, 100);
};
with in the same function.
Hope this helps you
You will need to attach your event handlers. It should go like this.
public static void CalculateAttributions(BackgroundWorker worker, string _filename, ComboBox cmb, OpenFileDialog open)
{
worker = new BackgroundWorker { WorkerReportsProgress = true };
worker.DoWork += new DoWorkEventHandler(worker_DoWork);
worker.ProgressChanged += new ProgressChangedEventHandler(worker_ProgressChanged);
worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted);
if (worker.IsBusy != true)
{
worker.RunWorkerAsync();
}
}
private void worker_DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = sender as BackgroundWorker;
while (wave.Position != length)
{
...Process..
worker.ReportProgress((100 * (int)(length / wave.Position)) / (int)(length / mainBuffer.Length));
}
}
private void worker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
progressBar1.Value = Math.Min(e.ProgressPercentage, 100);
}
private void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
//done
}
I think you should check this link.
http://msdn.microsoft.com/en-us/library/cc221403(v=vs.95).aspx
The idea is to get your work inside background worker. and after each milestone report progress on your progress bar.
create background worker object
attach event handlers
call RunWorkerAsynch()
add code inside event handlers
do work will have the real work and report to progress call
report to progress will simply tell your progress bar to move one step ahead
completed will be called once everything is done. you may want to show a message to user that the operation is completed.

Enable Button after Background Worker is Complete (C#) [duplicate]

In my application I need to perform a series of initialization steps, these take 7-8 seconds to complete during which my UI becomes unresponsive. To resolve this I perform the initialization in a separate thread:
public void Initialization()
{
Thread initThread = new Thread(new ThreadStart(InitializationThread));
initThread.Start();
}
public void InitializationThread()
{
outputMessage("Initializing...");
//DO INITIALIZATION
outputMessage("Initialization Complete");
}
I have read a few articles about the BackgroundWorker and how it should allow me to keep my application responsive without ever having to write a thread to perform lengthy tasks but I haven't had any success trying to implement it, could anyone tell how I would do this using the BackgroundWorker?
Add using
using System.ComponentModel;
Declare Background Worker:
private readonly BackgroundWorker worker = new BackgroundWorker();
Subscribe to events:
worker.DoWork += worker_DoWork;
worker.RunWorkerCompleted += worker_RunWorkerCompleted;
Implement two methods:
private void worker_DoWork(object sender, DoWorkEventArgs e)
{
// run all background tasks here
}
private void worker_RunWorkerCompleted(object sender,
RunWorkerCompletedEventArgs e)
{
//update ui once worker complete his work
}
Run worker async whenever your need.
worker.RunWorkerAsync();
Track progress (optional, but often useful)
a) subscribe to ProgressChanged event and use ReportProgress(Int32) in DoWork
b) set worker.WorkerReportsProgress = true; (credits to #zagy)
You may want to also look into using Task instead of background workers.
The easiest way to do this is in your example is Task.Run(InitializationThread);.
There are several benefits to using tasks instead of background workers. For example, the new async/await features in .net 4.5 use Task for threading. Here is some documentation about Task
https://learn.microsoft.com/en-us/dotnet/api/system.threading.tasks.task
using System;
using System.ComponentModel;
using System.Threading;
namespace BackGroundWorkerExample
{
class Program
{
private static BackgroundWorker backgroundWorker;
static void Main(string[] args)
{
backgroundWorker = new BackgroundWorker
{
WorkerReportsProgress = true,
WorkerSupportsCancellation = true
};
backgroundWorker.DoWork += backgroundWorker_DoWork;
//For the display of operation progress to UI.
backgroundWorker.ProgressChanged += backgroundWorker_ProgressChanged;
//After the completation of operation.
backgroundWorker.RunWorkerCompleted += backgroundWorker_RunWorkerCompleted;
backgroundWorker.RunWorkerAsync("Press Enter in the next 5 seconds to Cancel operation:");
Console.ReadLine();
if (backgroundWorker.IsBusy)
{
backgroundWorker.CancelAsync();
Console.ReadLine();
}
}
static void backgroundWorker_DoWork(object sender, DoWorkEventArgs e)
{
for (int i = 0; i < 200; i++)
{
if (backgroundWorker.CancellationPending)
{
e.Cancel = true;
return;
}
backgroundWorker.ReportProgress(i);
Thread.Sleep(1000);
e.Result = 1000;
}
}
static void backgroundWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
Console.WriteLine("Completed" + e.ProgressPercentage + "%");
}
static void backgroundWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
if (e.Cancelled)
{
Console.WriteLine("Operation Cancelled");
}
else if (e.Error != null)
{
Console.WriteLine("Error in Process :" + e.Error);
}
else
{
Console.WriteLine("Operation Completed :" + e.Result);
}
}
}
}
Also, referr the below link you will understand the concepts of Background:
http://www.c-sharpcorner.com/UploadFile/1c8574/threads-in-wpf/
I found this (WPF Multithreading: Using the BackgroundWorker and Reporting the Progress to the UI. link) to contain the rest of the details which are missing from #Andrew's answer.
The one thing I found very useful was that the worker thread couldn't access the MainWindow's controls (in it's own method), however when using a delegate inside the main windows event handler it was possible.
worker.RunWorkerCompleted += delegate(object s, RunWorkerCompletedEventArgs args)
{
pd.Close();
// Get a result from the asynchronous worker
T t = (t)args.Result
this.ExampleControl.Text = t.BlaBla;
};

Manipulating UI elements from within another thread

I'm trying to have a seperate thread in a WinForms C# application start a background worker which controls a ProgressBar (marquee). The issue is that when i try to set the bar to visible it just does nothing, and i've tried many forms of Invoke but they don't seem to help.
The following method progressBarCycle is called from a separate thread.
BackgroundWorker backgroundWorker = new BackgroundWorker();
public void progressBarCycle(int duration)
{
backgroundWorker.DoWork += new DoWorkEventHandler(backgroundWorker_DoWork);
backgroundWorker.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker_ProgressChanged);
backgroundWorker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundWorker_RunWorkerCompleted);
backgroundWorker.WorkerReportsProgress = true;
backgroundWorker.WorkerSupportsCancellation = true;
backgroundWorker.RunWorkerAsync(duration);
}
private void backgroundWorker_DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = sender as BackgroundWorker;
worker.ReportProgress(0);
DateTime end = DateTime.Now.AddMilliseconds((int)e.Argument);
while (DateTime.Now <= end)
{
System.Threading.Thread.Sleep(1000);
}
}
private void backgroundWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
if (!this.IsHandleCreated)
this.CreateHandle();
statusStrip1.Invoke((MethodInvoker)delegate
{
progressBar1.Visible = false;
});
// if (!this.IsHandleCreated)
// {
// this.CreateHandle();
// if (InvokeRequired) this.Invoke((MethodInvoker)(() => progressBar1.Visible = false));
// else progressBar1.Visible = false;
// }
// else
// if (InvokeRequired) this.Invoke((MethodInvoker)(() => progressBar1.Visible = false));
// else progressBar1.Visible = false;
}
private void backgroundWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
if (!this.IsHandleCreated)
this.CreateHandle();
statusStrip1.Invoke((MethodInvoker)delegate
{
progressBar1.Visible = true;
});
// if (!this.IsHandleCreated)
// {
// this.CreateHandle();
// if (InvokeRequired) this.Invoke((MethodInvoker)(() => progressBar1.Visible = true));
// else progressBar1.Visible = true;
// }
// else
// if (InvokeRequired) this.Invoke((MethodInvoker)(() => progressBar1.Visible = true));
// else progressBar1.Visible = true;
}
Am I missing something obvious here? The comment sections are other things I've tried.
ProgressChanged is already raised on the UI thread (via the sync-context); your ProgressChanged does not need to do that Invoke - it can manipulate the UI directly (by contrast, DoWork can absolutely not do that). Perhaps the real problem is that you don't do any worker.ReportProgress(...) inside the loop - so it only happens once at the start.
Here's a full example:
using System;
using System.ComponentModel;
using System.Threading;
using System.Windows.Forms;
static class Program
{
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
using (var worker = new BackgroundWorker {
WorkerReportsProgress = true })
using (var progBar = new ProgressBar {
Visible = false, Step = 1, Maximum = 100,
Dock = DockStyle.Bottom })
using (var btn = new Button { Dock = DockStyle.Top, Text = "Start" })
using (var form = new Form { Controls = { btn, progBar } })
{
worker.ProgressChanged += (s,a) => {
progBar.Visible = true;
progBar.Value = a.ProgressPercentage;
};
worker.RunWorkerCompleted += delegate
{
progBar.Visible = false;
};
worker.DoWork += delegate
{
for (int i = 0; i < 100; i++)
{
worker.ReportProgress(i);
Thread.Sleep(100);
}
};
btn.Click += delegate
{
worker.RunWorkerAsync();
};
Application.Run(form);
}
}
}
Run progressBarCycle from the UI thread. RunWorkerAsync will
create the new thread for you.
In backgroundWorker_ProgressChanged simply call
progressBar1.Visible = true;. There is no need for Invoke.
Better also add a progressBar1.Refresh(); .
Another possibility to be aware of is that the progress bar is running on your UI thread. In order for the progress bar to be displayed and redraw itself to show new progress amounts, the UI thread must be running freely, processing windows messages in the main application loop.
So if you start your background worker thread but then your UI thread sits in a busy wait loop waiting for it to complete, or goes off and does loads of other work, then it won't be processing windows messages and your progress bar will be "unresponsive". You need to release the UI thread so that this updating still happens (i.e. return from your event handler and allow the UI to continue running as normal).
The danger of this is that if the UI is active, then the user can still interact with it. You therefore have to write the UI to be aware when the background worker is active, and handle the situation properly (problems can include: Allowing the user to start the background worker again while it is already running, UI trying to display information while the worker thread is busily updating it, the user deciding to load a new document or quit while the background worker is busy, etc). The two main solutions to this are to wrap every bit of UI in a protective shield that stops anything dangerous being initiated while the background work is running (this can be a lot of work if you have lots of controls to wrap in this way, and it's easy to make a mistake that lets a bug slip through) or to leave the UI "unprotected" but add an IMessageFilter that stops all "dangerous" user interaction (clicks and keypresses) by suppressing their incoming windows messages (WM_KEYPRESS etc) while the background processing is active.

Run task asynchronously in C#

I have some process heavy tasks that run in my WinForms app. The problem is, while its running, it freeze the UI (UI main thread).
I haven't worked that much with threads and delegates in C# yet, and that's why I hope someone could help me to, how to handle those process heavy tasks, without freezing the UI, so the user don't think the app is crashing while waiting?
Eg. I have a call through my FrontController, that takes time:
_controller.testExportExcel(wrapper, saveDialog.FileName);
Since it's creating an Excel file. I won't the app to be responding on the UI while its working.
Another example of a process heavy task could be this:
private void dataGridView_liste_DataBindingComplete(object sender, DataGridViewBindingCompleteEventArgs e)
{
if (e.ListChangedType != ListChangedType.ItemDeleted)
{
foreach (DataGridViewRow r in dataGridView_liste.Rows)
{
DataGridViewCellStyle red = dataGridView_liste.DefaultCellStyle.Clone();
red.BackColor = Color.LightGreen;
if (r.Cells["News"].Value != null && (bool)r.Cells["News"].Value == true)
r.DefaultCellStyle = red;
}
}
}
Where the foreach loop takes time, and freeze the UI. An async thread running the process and automatically closing when its done, could be useful I think. But how does it work??
How about using a Task (if targetting .net 4)? This is considered as a replacement of the BackgroundWorker class since it supports nesting (parent/child tasks), task continuations, etc.
E.g.
private void dataGridView_liste_DataBindingComplete(object sender,
DataGridViewBindingCompleteEventArgs e)
{
Task t = Task.Factory.StartNew(() =>
{
// do your processing here - remember to call Invoke or BeginInvoke if
// calling a UI object.
});
t.ContinueWith((Success) =>
{
// callback when task is complete.
}, TaskContinuationOptions.NotOnFaulted);
t.ContinueWith((Fail) =>
{
//log the exception i.e.: Fail.Exception.InnerException);
}, TaskContinuationOptions.OnlyOnFaulted);
}
I answered a very similar question here
It boils down to using BackgroundWorker.
msdn provides an example:
using System.ComponentModel;
using System.Windows;
using System.Windows.Controls;
namespace SL_BackgroundWorker_CS
{
public partial class Page : UserControl
{
private BackgroundWorker bw = new BackgroundWorker();
public Page()
{
InitializeComponent();
bw.WorkerReportsProgress = true;
bw.WorkerSupportsCancellation = true;
bw.DoWork += new DoWorkEventHandler(bw_DoWork);
bw.ProgressChanged += new ProgressChangedEventHandler(bw_ProgressChanged);
bw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bw_RunWorkerCompleted);
}
private void buttonStart_Click(object sender, RoutedEventArgs e)
{
if (bw.IsBusy != true)
{
bw.RunWorkerAsync();
}
}
private void buttonCancel_Click(object sender, RoutedEventArgs e)
{
if (bw.WorkerSupportsCancellation == true)
{
bw.CancelAsync();
}
}
private void bw_DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = sender as BackgroundWorker;
for (int i = 1; (i <= 10); i++)
{
if ((worker.CancellationPending == true))
{
e.Cancel = true;
break;
}
else
{
// Perform a time consuming operation and report progress.
System.Threading.Thread.Sleep(500);
worker.ReportProgress((i * 10));
}
}
}
private void bw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
if ((e.Cancelled == true))
{
this.tbProgress.Text = "Canceled!";
}
else if (!(e.Error == null))
{
this.tbProgress.Text = ("Error: " + e.Error.Message);
}
else
{
this.tbProgress.Text = "Done!";
}
}
private void bw_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
this.tbProgress.Text = (e.ProgressPercentage.ToString() + "%");
}
}
}
Everything that runs in the DoWork event handler is asynchronous.
Everything that runs in ProgessChanged/RunWorkCompleted's event handlers is on the UI thread.
For your first example, a call to _controller.testExportExcel(), a BackgroundWorker or Task Parallel Library call (i.e. Task.Factory.StartNew(...)) would be appropriate to satify your requirement of keeping the UI responsive. Plenty of examples floating around, including the other answers here.
For your second example, you will find you can't put this on a background thread since it appears to be code that manipulates the UI. Specifically, if the implementation of your BackgroundWorker's DoWork event handler, or the delegate you pass to Task.Factory.StartNew(), or the method for a plain old thread touch the UI, you are highly likely (/certain?) to get an exception stating "Cross-thread operation not valid".
The reason for this is covered in this question. But I'm more surprised actually this is slow enough that you want to make it asynchronous. There might be some simple ways to make this code more responsive - Control.SuspendLayout() and .ResumeLayout() springs to mind.

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