Hello I recently started learning c# in Visual Studio..
I am trying to make a background process for my app.
I created a process and started it but I can't pause it without breaking my application.
public void WorkThreadFunction()
{
run = true;
for (int i = 0; i < 100; i++)
{
string message = "\r\n"+i+" Running...";
if (txtBox.InvokeRequired == true)
txtBox.Invoke((MethodInvoker)delegate { txtBox.Text += message; });
else
txtBox.Text += message;
Thread.Sleep(1000);
}
}
private void btnCapture_Click(object sender, EventArgs e)
{
Thread thread = new Thread(WorkThreadFunction);
if (run == false)
{
btnCapture.Text = "Abort";
lblStatus.Text = "Thread status: " + thread.ThreadState;
thread.Start();
}
else
{
btnCapture.Text = "Capture";
lblStatus.Text = "Thread status: " + thread.ThreadState;
//thread.Abort(); thread.Unset(); Thread.Sleep(999999); thread.WaitOne();
txtBox.Text += "Work!";
}
}
Also thread.ThreadState always returns "Unstarted"...
I tried using "ManualResetEvent" but this just freezes my app...
Help? :S
That's correct, you check ThreadState before calling Start(), thus it's unstarted.
As an unrelated note, you don't need that InvokeRequired check, it's always required in this context.
Related
I am trying to build a simple code that joins csv files into one distinct file, but my background worker seems to have a mind of its own and my code gets stuck every time.
Here is my code for joining the file using the background worker:
private void backgroundWorker_DoWork(object sender, DoWorkEventArgs e)
{
try
{
if (string.IsNullOrEmpty(saveFilePath))
{
this.Invoke(new MethodInvoker(delegate
{
btnBrowseSave.PerformClick();
}));
}
if (!string.IsNullOrEmpty(saveFilePath))
{
if (dragEventArgs != null)
files = (string[])dragEventArgs.Data.GetData(DataFormats.FileDrop);
int filesCount = 0, rowsCount = 0;
foreach (string file in files)
{
filesCount++;
int fileTotalLines = File.ReadAllLines(file).Length;
this.Invoke(new MethodInvoker(delegate
{
lblFileName.Text = "Loading file: " + file.Substring(file.LastIndexOf("\\") + 1);
lblTotalFiles.Text = "File " + filesCount + " of " + files.Length;
}));
using (StreamReader reader = new StreamReader(file))
{
using (StreamWriter writer = new StreamWriter(saveFilePath))
{
while (!reader.EndOfStream)
{
try
{
while (stopPosition > rowsCount)
{
reader.ReadLine();
rowsCount++;
}
string email = reader.ReadLine().Trim();
if (!string.IsNullOrEmpty(email) && !dicEmails.ContainsKey(email))
{
dicEmails.Add(email, null);
writer.WriteLine(email);
}
rowsCount++;
stopPosition++;
backgroundWorker.ReportProgress((rowsCount * 100 / fileTotalLines), (int)ProgressType.Row);
if (backgroundWorker.CancellationPending)
return;
}
catch (Exception ex)
{
hadReadErrors = true;
}
}
}
}
backgroundWorker.ReportProgress(0, (int)ProgressType.Row);
backgroundWorker.ReportProgress((filesCount * 100 / files.Length), (int)ProgressType.File);
}
}
}
catch (Exception ex)
{
hadReadErrors = true;
MessageBox.Show(ex.Message);
}
finally
{
backgroundWorker.Dispose();
}
}
private void backgroundWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
try
{
switch ((int)e.UserState)
{
case (int)ProgressType.Row:
lblFileProgress.Text = e.ProgressPercentage + "%";
fileProgressBar.Value = e.ProgressPercentage;
break;
case (int)ProgressType.File:
lblTotalProgress.Text = e.ProgressPercentage + "%";
totalProgressBar.Value = e.ProgressPercentage;
break;
}
}
catch (Exception ex) { }
}
When I run in debug mode and go with the debugger I don't see any problems, but when I let the code run it self it gets stuck and crashes.
Can someone PLEASE help me and tell me what am I missing out here ?
Here is the exception:
Managed Debugging Assistant 'ContextSwitchDeadlock' has detected a problem in
'C:\Users\Develop\Desktop\ExcelBuilder\ExcelBuilder\bin\Debug\ExcelBuilder.vshost.exe'.
Additional information: The CLR has been unable to transition from COM context 0x90fb78
to COM context 0x90fc30 for 60 seconds. The thread that owns the destination
context/apartment is most likely either doing a non pumping wait or processing a very
long running operation without pumping Windows messages. This situation generally has
a negative performance impact and may even lead to the application becoming non
responsive or memory usage accumulating continually over time. To avoid this problem,
all single threaded apartment (STA) threads should use pumping wait primitives
(such as CoWaitForMultipleHandles) and routinely pump messages during long running operations.
I did a small example of your program, trying to guess what it must do (https://github.com/anderson-rancan/stackoverflow_28798348, drag and drop 4 files to the groupbox, lorem?.csv), and there is a few things that you should consider:
never try/catch a unknown exception, every exception or something you cannot deal with (https://msdn.microsoft.com/en-us/library/ms182137.aspx)
when using a BackgroundWorker on a form, use the "sender" for references to it, it's a thread safe object to your method (https://msdn.microsoft.com/en-us/library/cc221403(v=vs.95).aspx)
maybe you are updating too fast your form, change your Invoke method to BeingInvoke, and do the update async (https://msdn.microsoft.com/en-us/library/0b1bf3y3(v=vs.110).aspx)
So, just fixing that was possible to run it, like this:
private void backgroundWorker_DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker bckw = (BackgroundWorker)sender; // Recommended way, thread safe
try
{
if (string.IsNullOrEmpty(saveFilePath))
{
this.Invoke(new MethodInvoker(delegate
{
btnBrowseSave.PerformClick();
}));
}
if (!string.IsNullOrEmpty(saveFilePath))
{
if (dragEventArgs != null)
files = (string[])dragEventArgs.Data.GetData(DataFormats.FileDrop);
int filesCount = 0, rowsCount = 0;
foreach (string file in files)
{
filesCount++;
double fileTotalLines = File.ReadAllLines(file).Length;
this.BeginInvoke(new MethodInvoker(delegate
{
lblFileName.Text = "Loading file: " + file.Substring(file.LastIndexOf("\\") + 1);
lblTotalFiles.Text = "File " + filesCount + " of " + files.Length;
})); // Invoke async, way too fast this...
using (StreamReader reader = new StreamReader(file))
{
using (StreamWriter writer = new StreamWriter(saveFilePath))
{
while (!reader.EndOfStream)
{
try
{
while (stopPosition > rowsCount)
{
reader.ReadLine();
rowsCount++;
} // why are you using that? it won't get TRUE
string email = reader.ReadLine().Trim();
if (!string.IsNullOrEmpty(email) && !dicEmails.ContainsKey(email))
{
dicEmails.Add(email, null);
writer.WriteLine(email);
}
rowsCount++;
stopPosition++;
bckw.ReportProgress((int)Math.Round(rowsCount * 100 / fileTotalLines, 0), (int)ProgressType.Row);
if (bckw.CancellationPending)
return;
}
catch (Exception ex)
{
hadReadErrors = true;
throw; // Throw it again, or you won't know the Exception
}
}
}
}
bckw.ReportProgress(0, (int)ProgressType.Row);
bckw.ReportProgress((filesCount * 100 / files.Length), (int)ProgressType.File);
}
}
}
catch (Exception ex)
{
hadReadErrors = true;
MessageBox.Show(ex.Message);
}
finally
{
bckw.Dispose();
}
}
private void backgroundWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
//try
//{
switch ((int)e.UserState)
{
case (int)ProgressType.Row:
lblFileProgress.Text = e.ProgressPercentage + "%";
if (e.ProgressPercentage <= fileProgressBar.Maximum)
fileProgressBar.Value = e.ProgressPercentage;
break;
case (int)ProgressType.File:
lblTotalProgress.Text = e.ProgressPercentage + "%";
totalProgressBar.Value = e.ProgressPercentage;
break;
}
//}
//catch (Exception ex) { } // Don't catch everything
}
Finally, may I suggest another approach?
You're reading the file two times: one to get the number of lines, and another to read each line. Try to do this just once, you'll get a better result.
To get used to and get trained using Backgroundworker for my Project, i used a sample code which runs smoothly except when it comes to handling error condition it doesn't allow me to use (e.Error!=null) facility of RunWorkerCompletedEventArgs e.I want to handle error like the way cancel and successful completion works for me.
Suggestions please!
Following is the code:
private void DoWork(object sender, DoWorkEventArgs e)
{
Random rand = new Random();
for (int i = 0; i < 10; i++)
{
if (this.backgroundWorker.CancellationPending)
{
e.Cancel = true;
break;
}
// report progress
this.backgroundWorker.ReportProgress(-1, string.Format("Performing step {0}...", i + 1));
// simulate operation step
System.Threading.Thread.Sleep(rand.Next(1000, 10000));
//setting simulateError to true after inducing error(a button)
if (this.simulateError)
{
this.simulateError = false;
//needs a code to use (e.Error!=null) in
RunWorkerCompleted().
//A jump to RunWorkerCompleted is required here.
}
}
}
private void RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
// hide animation
this.pictureBox.Image = null;
// show result indication
if (e.Cancelled)
{
////works nice
this.labelProgress.Text = "Operation cancelled by the user!";
this.pictureBox.Image = Properties.Resources.WarningImage;
}
else
{
//doesn't execute at all....why?
if (e.Error != null)
{
this.labelProgress.Text = "Operation failed: " + e.Error.Message;
this.pictureBox.Image = Properties.Resources.ErrorImage;
}
else
{
//works nice
this.labelProgress.Text = "Operation finished successfuly!";
this.pictureBox.Image = Properties.Resources.InformationImage;
}
}
// restore button states
this.buttonStart.Enabled = true;
this.buttonCancel.Enabled = false;
this.buttonError.Enabled = false;
}
I induce error using simulateError ,for the purpose to show peculiar error message how should i use
if (e.Error != null)
{
this.labelProgress.Text = "Operation failed: " + e.Error.Message;
My Program isn't coming to private void RunWorkerCompleted(object sender, ,RunWorkerCompletedEventArgs e) in case of error. In other cases(cancellation,succesful completion) it executes right.
To get used to and get trained using Backgroundworker for my Project
Why would you do that? Task.Run() is better than BackgroundWorker in every way.
Now to your actual question: to cause an error in a BackgroundWorker, use the standard mechanism for that in .Net: exceptions:
if (this.simulateError)
{
this.simulateError = false;
throw new Exception("Simulating error.");
}
I have a thread that calls a static method to update file properties using WindowsAPICodePack ShellPropertyWriter and BackgroundWorker. The thread calls the method below for each file in a folder of 1000+ files and hangs on the ShellPropertyWriter.close() after the 700th update or so.
Nothing to do with the file itself, tried using different files that successfully updated before.
public static bool ShellPropertyUpdate(VideoEntry mediaEntry)
{
try
{
ShellFile mediafile = ShellFile.FromFilePath(mediaEntry.FilePath);
ShellPropertyWriter pw = mediafile.Properties.GetPropertyWriter();
pw.WriteProperty(SystemProperties.System.Music.Artist, mediaEntry.Actor);
pw.WriteProperty(SystemProperties.System.Music.Genre, mediaEntry.Genre);
pw.WriteProperty(SystemProperties.System.Rating, mediaEntry.Rating);
pw.Close();
}
catch (Exception ex)
{
return false;
}
return true;
}
private void mnuWriteMetadataToFiles_Click(object sender, EventArgs ev)
{
this.WorkerThread = new BackgroundWorker();
this.WorkerThread.DoWork += new DoWorkEventHandler(WorkerThread_WriteMetadataToFiles);
this.WorkerThread.ProgressChanged += new ProgressChangedEventHandler(WorkerThread_ProgressChanged);
this.WorkerThread.RunWorkerCompleted += (s, e) => WorkerThread_Completed("Writing metadata to files", s, e);
this.WorkerThread.WorkerReportsProgress = true;
this.WorkerThread.WorkerSupportsCancellation = true;
this.WorkerThread.RunWorkerAsync(WMPlayer);
}
private void WorkerThread_WriteMetadataToFiles(object sender, DoWorkEventArgs e)
{
int counter = 0;
BackgroundWorker worker = (BackgroundWorker)sender;
MediaPlayer wmp = (MediaPlayer)e.Argument;
// ... Loop with the foreach video in the library and write it to file.
foreach (VideoEntry entry in wmp.Videos)
{
if (worker.CancellationPending)
{
e.Cancel = true;
}
else
{
worker.ReportProgress(counter, "Updating '" + entry.Filename + "'" + Environment.NewLine + "Processing file");
if (VideoToFile.ShellPropertyUpdate(entry))
{
result &= true;
}
counter++;
}
}
e.Result = result;
}
Never heard of this assembly before, but it smells like handle exhaustion to me. Try this instead:
using (ShellFile mediafile = ShellFile.FromFilePath(mediaEntry.FilePath))
{
ShellPropertyWriter pw = mediafile.Properties.GetPropertyWriter();
pw.WriteProperty(SystemProperties.System.Music.Artist, mediaEntry.Actor);
pw.WriteProperty(SystemProperties.System.Music.Genre, mediaEntry.Genre);
pw.WriteProperty(SystemProperties.System.Rating, mediaEntry.Rating);
pw.Close();
}
Here every file handle is closed immediately, instead of at garbage collector's discretion. ShellFile must implement IDisposable for this to work, otherwise this code will not compile. I'm fairly certain that ShellFile implements it.
Apparently it does have something to do with the files themselves. I took out few problem files and the Thread continued processing until the next problem file. I have no clue what's wrong with the file, however I'm willing to pass on updating problem files. Is there a way to stop/kill the thread? I can't use DoWorkEventArgs.cancel() since the thread is hanging and not coming back.
I have tried to work around this as well as debug but I'm at a loose end here :( is there any alternative to using this to check for a client connection? This code works fine in a console application so i am guessing the thread is being blocked, although it may be something else i can't see?
public partial class Form1 : Form
{
Socket s;
Declatation of socket.
private void startButton_Click(object sender, EventArgs e)
{
checkTimer.Enabled = true;
if (bw.IsBusy != true)
{
bw.RunWorkerAsync();
}
}
Background thread to start on button press.
private void bw_DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = sender as BackgroundWorker;
working();
}
Thread runs the "working" method.
private void working()
{
if (threadFirstRun == true)
{
threadFirstRun = false;
}
try
{
String tempAddr = tbAddr.Text;
IPAddress ipAd = IPAddress.Parse("147.197.204.172");
// use local m/c IP address, and
// use the same in the client
String tempPort = tbPort.Text;
/* Initializes the Listener */
TcpListener myList = new TcpListener(ipAd, 3000);
/* Start Listeneting at the specified port */
myList.Start();
tcConnection1 = "Console:\n" + "The server is running at port 3000...";
tcConnection2 = "\n" + "The local End point is :" + myList.LocalEndpoint;
tcConnection3 = "\n" + "Waiting for a connection.....";
while (true)
{
s = myList.AcceptSocket();
if (s != null)
{
if (connectionEstab == false)
{
tcEstab = "\n" + "Connection accepted from " + s.RemoteEndPoint;
connectionEstab = true;
}
byte[] b = new byte[100];
int k = s.Receive(b);
//Console.WriteLine("Recieved...");
for (int i = 0; i < k; i++)
{
//Console.Write(Convert.ToChar(b[i]));
tcValue = tcValue + Convert.ToString(b[i]);
valueArray[ii] = (float)Convert.ToDouble(b[i]);
}
tcValue = tcValue + "\n";
ii++;
}
else
{
Thread.Sleep(200);
}
}
ASCIIEncoding asen = new ASCIIEncoding();
s.Send(asen.GetBytes("The string was recieved by the server."));
rtbConsole.Text = rtbConsole.Text + "\n" + "Sent Acknowledgement";
/* clean up */
s.Close();
myList.Stop();
}
catch (Exception ex)
{
tcError = "\n\n" + "Error..... " + ex.StackTrace;
}
}
Working method starts the server and blocks upon calling myList.AcceptSocket();?
private void bw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
if ((e.Cancelled == true))
{
rtbConsole.Text = rtbConsole.Text + "\n" + "Canceled!";
}
else if (!(e.Error == null))
{
rtbConsole.Text = rtbConsole.Text + "\n\n" + ("Error: " + e.Error.Message);
}
else
{
rtbConsole.Text = rtbConsole.Text + "\n" + "Done!";
}
}
private void bw_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
rtbConsole.Text = rtbConsole.Text + "\n" + (e.ProgressPercentage.ToString() + "%");
}
private void stopButton_Click(object sender, EventArgs e)
{
checkTimer.Enabled = false;
if (bw.WorkerSupportsCancellation == true)
{
bw.CancelAsync();
}
}
Other methods for some completeness.
Sending data from my android device is received by a console app running 1 thread, however nothing seems to happen in this windows form application upon sending data to the same ip and port from the same program on the same device. The separate thread just stays blocked and the android app cannot complete communication to send the data.
It's supposed to block. It can never return null. (Why is everybody doing this? It's like nobody on the web uses Accept correctly.)
Your problem is that after accepting one connection you process that connection and do nothing to resume accepting. The standard pattern is:
while (true) {
var connectionSocket = listeningSocket.Accept();
ProcessAsynchronously(connectionSocket);
}
Make sure ProcessAsynchronously returns immediately. Start a new Task or use async/await.
As you never exit the while loop you never get to sending data. Move all processing logic into ProcessAsynchronously.
It is supposed to block. From MSDN:
AcceptSocket is a blocking method that returns a Socket that you can
use to send and receive data. If you want to avoid blocking, use the
Pending method to determine if connection requests are available in
the incoming connection queue.
You can turn your whole implementation to use the async version: AcceptSocketAsync. Note this wont block your method, it will yield control back to the caller until a new Socket has been connected.
private async void bw_DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = sender as BackgroundWorker;
await WorkingAsync();
}
And inside WorkingAsync:
private Task WorkingAsync
{
// Do all other stuff,
Socket socket = await myList.AcceptSocketAsync();
// Do rest of stuff with the socket
}
I recommend you like at What is the async/await equivalent of a ThreadPool server? for a full implementation of an async tcp connection handler
I've seen some great answers here and was wondering if someone could help me out.
Here's my code:
namespace expandGUIWPF
{
public static string getSHA256b64(string filepath)
{
byte[] bytes = SHA256.Create().ComputeHash(File.ReadAllBytes(filepath));
return Convert.ToBase64String(bytes);
}
private void btnRun_Click(object sender, RoutedEventArgs e)
{
{
string folder = txtFolder.Text;
string filelist = folder + "\\FileList.txt";
string[] test = Directory.GetFiles(folder, "*", System.IO.SearchOption.AllDirectories);
File.WriteAllLines(filelist, test);
int length = File.ReadLines(filelist).Count();
pBar1.Minimum = 1;
pBar1.Maximum = length;
File.WriteAllLines(filelist, test);
using (StreamReader sr = new StreamReader(filelist))
{
string line;
while ((line = sr.ReadLine()) != null)
{
string oldfile = line;
string newfile = oldfile + ".expanded";
string oldhash = "";
string newhash = "";
try
{
ProcessStartInfo startInfo = new ProcessStartInfo(#"C:\test\test.exe", oldfile + " " + newfile);
startInfo.WindowStyle = ProcessWindowStyle.Hidden;
Process.Start(startInfo);
Thread.Sleep(1000);
if (File.Exists(oldfile))
{
oldhash = getSHA256b64(oldfile);
}
if (File.Exists(newfile))
{
newhash = getSHA256b64(newfile);
File.Delete(oldfile);
File.Move(newfile, oldfile);
}
pBar1.Value = pBar1.Value + 1;
txtLog.AppendText(oldfile + "\r\n Old: " + oldhash + "\r\n New: " + newhash + "\r\n");
if (!(oldhash == newhash))
{
txtLog.AppendText("Successfully expanded file \r\n");
}
else
{
txtLog.AppendText("Unable to expand file \r\n");
}
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
}
}
}
}
}
The problem is that my progressbar isn't updating. I know a little C# but I'm a beginner to WPF and can't get my head around setting up a background worker to update my UI. Would someone be able to give me a few pointers please? Currently the app works fine, but the progressbar jumps to 100% finished and all of the text suddenly appears.
Thanks in advance!
Tom
First you'll want your background worker to handle the processes in its DoWork event. Within that event you can call the ProgressChanged event to update the progress bar. Below is an example:
private void btnRun_Click(object sender, RoutedEventArgs e)
{
if(workerThread.IsBusy == false) // Make sure someone doesn't click run multiple times by mistake
{
pBar1.Value = 0;
workerThread.RunWorkerAsync();
}
}
private void workerThread_DoWork(object sender, DoWorkEventArgs e)
{
// Definitions and so forth
pBar1.Minimum = 0;
pBar1.Maximum = length;
int status = 0;
using (StreamReader sr = new StreamReader(filelist))
{
string line;
while ((line = sr.ReadLine()) != null)
{
// Try/Catch work here
status++;
workerThread.ReportProgress(status);
}
}
private void workerThread_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
pBar1.Value = e.ProgressPercentage;
}
Just understand that the thread that's running the Form is the same one that will be used to update the form's controls. So if you have 'stuff' to do - like encrypting / decrypting lines from a file - you need to perform those items on another thread with a callback, otherwise the form display wont update until it's done with your stuff to do. You can raise events from inside a worker thread -- and catch them using an event handler on the main (form) thread to update the progress bar.
It seems that your UI thread is being blocked, in windows forms programming you have one message pump and while you main thread (UI) is doing something else it has to wait before it can process messages. You can fix this problem by setting up a background worker to send updates
For more information on UI thread and the message pump see this
http://www.codeproject.com/Articles/10311/What-s-up-with-BeginInvoke
For infomation on the backgroundworker thread see this
http://msdn.microsoft.com/en-us/library/system.componentmodel.backgroundworker.aspx
Small Example code
// This event handler is where the time-consuming work is done.
private void backgroundWorker1_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);
}
}
}