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C# Backgroundworker ReportProgress() not executing

Hello I am trying to populate a progress bar but the ReportProgress call its not been executed for some reason.
Here is my code
//create status_Worker
status_Worker = new BackgroundWorker();
status_Worker.DoWork += new DoWorkEventHandler(Status_DoWork);
status_Worker.ProgressChanged += new ProgressChangedEventHandler(Worker_ProgressChanged);
status_Worker.WorkerReportsProgress = true;
status_Worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(Worker_RunWorkerCompleted);
private void Status_DoWork(object sender, DoWorkEventArgs e)
{
//make call to Logger class getStatus method
_logger.getStatus(sender);
}
private void Worker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
progressbar1.Value = e.ProgressPercentage;
}
private void Worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
if (e.Error != null)
{
MessageBox.Show(e.Error.Message);
return;
}
else
{
Start_button.IsEnabled = true;
}
}
private void Start_button_Click(object sender, RoutedEventArgs e)
{
//initiate status_Worker when button is clicked
status_Worker.RunWorkerAsync();
Start_button.IsEnabled = false;
}
Now inside the Logger class I have the getStatus() method. i make a call to a local server to get status of the files been processed and all that works and I see the values been updated automatically on my MainWindow.Status.
public async Task getStatus(object sender)
{
BackgroundWorker statusWorker = (BackgroundWorker)sender;
//Making a call to ReportProgress here works and it shows the progress bar
//statusWorker.ReportProgress(99);
//REQUEST STATUS from a server
//Status format
//CurrentParser, NumberOfFilesToParse,CountOfCompletedFiles,Status, NumberOfProcessRunning
int CountOfCompletedFiles;
int NumberOfFilesToParse;
int percent;
string status = "Running";
string[] stats;
char[] delimiterChars = { ' ', ',', '.', ':', '\t' };
while(status!="Complete")
{
var getstatus = await request.GetStringAsync("http://localhost:8085/status");
logs.Add(getstatus);
stats = getstatus.Split(delimiterChars);
NumberOfFilesToParse = Int32.Parse(stats[1]);
CountOfCompletedFiles = Int32.Parse(stats[2]);
status = stats[3];
Thread.Sleep(1000);
MainWindow.main.Status = "Files to process: " + NumberOfFilesToParse + " Files completed: " + CountOfCompletedFiles + " Status: " + status;
if(NumberOfFilesToParse!=0 && status!="Complete")
{
percent = (CountOfCompletedFiles * 100) / NumberOfFilesToParse;
//a call to ReportProgress here stalls the program at this point
//statusWorker.ReportProgress(percent);
}
}
MainWindow.main.Status = "Completed!";
}
A call to ReportProgress at the start of the getStatus method works but a call to ReportProgress during or after my while loop results in process stalling at that point. Even when using static numbers ReportProgress(99) it only executes at the beginning

Your Status_DoWork method is doing fire-and-forget. It's calling an async Task method and then ignoring the Task it returns.
One of the problems you've run into is that BackgroundWorker simply doesn't work with async. What's actually happening is that as soon as the first await is reached in getStatus, it returns an incomplete Task to Status_DoWork, which then exits. This causes the BackgroundWorker to finish, so raising progress events no longer makes sense for that BackgroundWorker.
The modern replacement for BackgroundWorker is Task.Run, which includes support for progress reporting. Ideally, you would only use Task.Run for CPU-bound methods, not the I/O-bound methods:
private void Start_button_Click(object sender, RoutedEventArgs e)
{
Start_button.IsEnabled = false;
var progress = new Progress<int>(update => progressbar1.Value = update);
try
{
await _logger.getStatus(progress);
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
finally
{
Start_button.IsEnabled = true;
}
}
public async Task getStatus(IProgress<int> progress)
{
int CountOfCompletedFiles;
int NumberOfFilesToParse;
int percent;
string status = "Running";
string[] stats;
char[] delimiterChars = { ' ', ',', '.', ':', '\t' };
while(status!="Complete")
{
var getstatus = await request.GetStringAsync("http://localhost:8085/status");
logs.Add(getstatus);
stats = getstatus.Split(delimiterChars);
NumberOfFilesToParse = Int32.Parse(stats[1]);
CountOfCompletedFiles = Int32.Parse(stats[2]);
status = stats[3];
await Task.Run(() => Thread.Sleep(1000)); // process file in Task.Run
MainWindow.main.Status = "Files to process: " + NumberOfFilesToParse + " Files completed: " + CountOfCompletedFiles + " Status: " + status;
if(NumberOfFilesToParse!=0 && status!="Complete")
{
percent = (CountOfCompletedFiles * 100) / NumberOfFilesToParse;
progress.Report(percent);
}
}
MainWindow.main.Status = "Completed!";
}

How do I bypass code in the RunWorkerCompleted event if an error occurs?

I wrote a program that creates an XML file from the contents of an Excel spreadsheet. The program works and I am now making it more robust by adding error checking. For example, if the Excel spreadsheet does not contain a required XML tag, the program displays an error and returns from the main program. When an error occurs, the RunWorkerCompleted() event fires, and code executes that shouldn't execute because an error occurred. My question is how to determine if an error occurred so I can bypass certain code in the RunWorkerCompleted() event.
I tried calling bgw.CancelAsync() in the main program where the error is detected, but RunWorkerCompletedEventArgs e.Cancelled is false so it doesn't work.
Here are some excerpts from my code. The progress bar is started in the click event of a button. It works, but I had to declare cellsProcessed, rowCount, and colCount as global because I couldn't figure out how to pass them to bgw_DoWork().
private void button_create_Click(object sender, EventArgs e)
{
// Define the event that fires when the progress bar finishes
bgw.RunWorkerCompleted += bgw_Complete;
rowCount = xmlRange.Rows.Count; // Declared as global
colCount = xmlRange.Columns.Count; // Declared as global
// Start the progress bar thread
if (!bgw.IsBusy)
{
bgw.RunWorkerAsync();
}
// Read the header in row 1 and return an error if it isn't valid
for (colIdx = 1; colIdx <= colCount; colIdx++)
{
if ((xmlRange.Cells[1, colIdx] != null) && (xmlRange.Cells[1, colIdx].Value2 != null))
{
cellContents = xmlRange.Cells[1, colIdx].Value2.ToString();
switch (colIdx)
{
case 1:
if (cellContents != "Tag")
{
error = true;
errText = "Cell A1 must contain 'Tag'";
}
break;
case 2:
if (cellContents != "Type")
{
error = true;
errText = "Cell B1 must contain 'Type'";
}
break;
if (error)
{
bgw.CancelAsync();
MessageBox.Show(errText, "Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
// Close Excel resources
xmlWorkbook.Close();
xmlSpreadsheet.Quit();
Marshal.ReleaseComObject(xmlRange);
Marshal.ReleaseComObject(xmlWorksheet);
Marshal.ReleaseComObject(xmlWorkbook);
Marshal.ReleaseComObject(xmlSpreadsheet);
GC.Collect();
return;
}
private void bgw_DoWork(object sender, DoWorkEventArgs e)
{
if (bgw.CancellationPending)
{
e.Cancel = true;
}
else
{
label_pctComplete.Text = "Completed " + progressBar.Value.ToString() + "%";
bgw.ReportProgress((100 * ++cellsProcessed) / (rowCount * colCount));
}
}
private void bgw_Complete(object sender, RunWorkerCompletedEventArgs e)
{
if (!e.Cancelled)
{
label_pctComplete.Visible = false;
progressBar.Visible = false;
// Inform the user that the XML file was created
label_created.Visible = true;
label_created.Text = "Done!...Created " + textBox_outputFile.Text;
// Enable the button so the user can view the XML Limit File
button_openLimitFile.Enabled = true;
}
}
private void bgwProgressChanged(object sender, ProgressChangedEventArgs e)
{
progressBar.Value = e.ProgressPercentage;
}
Thank you for any help.

How to advance the progress bar for specific operation (C#)

my problem is, I have SQL server and i want while the user take a backup of the database, a progress bar advances as the REAL backup operation do.
for example if i have 100 tables, so, the progress bar should be advanced by 1 for each 1 table that have been backed-up.
Or, id doesn't matter per table, just simply, the progress bar advances correctly with the operation.
Thank you, the code is below..
try
{
SaveFileDialog saveFile = new SaveFileDialog();
saveFile.Filter = "Backup (*.bac) | *.bac";
progressBar1.Visible = true;
if (saveFile.ShowDialog() == DialogResult.OK)
{
conn.Open();
com = new SqlCommand("BACKUP DATABASE ServerDB TO DISK = '"+saveFile.FileName+"'", conn);
com.ExecuteNonQuery();
conn.Close();
progressBar1.Visible = false;
MessageBox.Show("Your backup (" + saveFile.FileName + ") has been created successfuly", "Backup done", MessageBoxButtons.OK);
}
else
{
progressBar1.Visible = false;
}
}
catch(Exception exp)
{
MessageBox.Show(exp.ToString());
conn.Close();
}

Firt, a pet peeve of mine is proper Exception Handling and you have some mistakes in there: You catch Exception. You are not closing the connection via finally and thus only in the Exception case. If you want to avoid any followup problem, you really need to read up on this. Here are two articles I link often:
http://blogs.msdn.com/b/ericlippert/archive/2008/09/10/vexing-exceptions.aspx
http://www.codeproject.com/Articles/9538/Exception-Handling-Best-Practices-in-NET
As for the actuall problem:
You can only do Progress Reporting between Distinct Operations. Mostly doing the level of reporting you want is way, way more trouble then it is worth.
While some really new classes do support deep Progress Reporting, for most other cases it means you have to re-do the existing code. Often reverse-engineering it down to the lowest loop you want to do Progress reporting on. On top of that you will need some approach of Multitasking. While the long running operation has not returned, no other code on the UI thread can run. Including the code that actually dispalys any updates. I wrote some decent example code for BackgroundWorker a while back. It should get you onto the right track:
#region Primenumbers
private void btnPrimStart_Click(object sender, EventArgs e)
{
if (!bgwPrim.IsBusy)
{
//Prepare ProgressBar and Textbox
int temp = (int)nudPrim.Value;
pgbPrim.Maximum = temp;
tbPrim.Text = "";
//Start processing
bgwPrim.RunWorkerAsync(temp);
}
}
private void btnPrimCancel_Click(object sender, EventArgs e)
{
if (bgwPrim.IsBusy)
{
bgwPrim.CancelAsync();
}
}
private void bgwPrim_DoWork(object sender, DoWorkEventArgs e)
{
int highestToCheck = (int)e.Argument;
//Get a reference to the BackgroundWorker running this code
//for Progress Updates and Cancelation checking
BackgroundWorker thisWorker = (BackgroundWorker)sender;
//Create the list that stores the results and is returned by DoWork
List<int> Primes = new List<int>();
//Check all uneven numbers between 1 and whatever the user choose as upper limit
for(int PrimeCandidate=1; PrimeCandidate < highestToCheck; PrimeCandidate+=2)
{
//Report progress
thisWorker.ReportProgress(PrimeCandidate);
bool isNoPrime = false;
//Check if the Cancelation was requested during the last loop
if (thisWorker.CancellationPending)
{
//Tell the Backgroundworker you are canceling and exit the for-loop
e.Cancel = true;
break;
}
//Determin if this is a Prime Number
for (int j = 3; j < PrimeCandidate && !isNoPrime; j += 2)
{
if (PrimeCandidate % j == 0)
isNoPrime = true;
}
if (!isNoPrime)
Primes.Add(PrimeCandidate);
}
//Tell the progress bar you are finished
thisWorker.ReportProgress(highestToCheck);
//Save Return Value
e.Result = Primes.ToArray();
}
private void bgwPrim_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
pgbPrim.Value = e.ProgressPercentage;
}
private void bgwPrim_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
pgbPrim.Value = pgbPrim.Maximum;
this.Refresh();
if (!e.Cancelled && e.Error == null)
{
//Show the Result
int[] Primes = (int[])e.Result;
StringBuilder sbOutput = new StringBuilder();
foreach (int Prim in Primes)
{
sbOutput.Append(Prim.ToString() + Environment.NewLine);
}
tbPrim.Text = sbOutput.ToString();
}
else
{
tbPrim.Text = "Operation canceled by user or Exception";
}
}
#endregion

Background Worker is called twice

I have a problem with background worker, it gets called twice thus, increasing the time of execution for my long routine, I created background worker manually so, there is no chance for the DoWork to be initialized within the initializeComponent() method, any help is appreciated.
here is my code:
// constructor
public TeacherScheduleForm(Therapist therapist)
{
this.therapist = therapist;
InitializeComponent();
bw = new BackgroundWorker();
bw.WorkerSupportsCancellation = true;
bw.WorkerReportsProgress = true;
bw.DoWork += bw_DoWork;
bw.ProgressChanged += bw_ProgressChanged;
bw.RunWorkerCompleted += bw_RunWorkerCompleted;
load = new LoadingForm();
}
private void bw_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
load.AppendProgress(e.ProgressPercentage);
// load.AppendText(e.ProgressPercentage.ToString() + "%");
Console.Write("Progress: " + e.ProgressPercentage);
// MessageBox.Show("Progress : " + e.ProgressPercentage);
}
private void bw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
if ((e.Cancelled == true))
{
MessageBox.Show("Cancelled");
}
else if (!(e.Error == null))
{
MessageBox.Show("Error : " + e.Error);
}
else
{
updateUI();
load.Close();
Console.Write( "Done!");
}
}
// do work of background worker
private void bw_DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = sender as BackgroundWorker;
for (int i = 1; (i <= 2); i++)
{
if ((worker.CancellationPending == true))
{
e.Cancel = true;
break;
}
else
{
// Perform a time consuming operation and report progress.
Console.Write("Before Doing work");
setup(therapist.therapistID + "", schoolYear);// the time consuming operation
Console.Write("Doing work");
//System.Threading.Thread.Sleep(100);
worker.ReportProgress((i*5));
}
}
}
The background worker is called when the user selects the school year through a combo box which is in this code below:
private void comboBoxSchoolYear_SelectedIndexChanged(object sender, EventArgs e)
{
//load = new LoadingForm();
schoolYear = int.Parse(comboBoxSchoolYear.SelectedValue + "");
try{
if (!bw.IsBusy)
{
bw.RunWorkerAsync();
load.ShowDialog();
}
else
{
bw.CancelAsync();
}
}
catch(Exception ex)
{
Console.Write("Error : " + ex.Message);
}
}

You are loading the form after creating the event-handler. Thats the only point I can think off doing the trouble. Try to load the form first and then create the handler.
Reason: At InitializeComponent(); the IndexChanged normally will fire up because the control is set at this point with its index. I havnt noticed this behaviour on FormLoad till now. But as I cant see any other problem in here its worth a try.
IF this doesnt solves it, you should also take care if TeacherScheduleForm is being called twice.
Something handy for debugging-purposes:
MessageBox.Show((new StackTrace().GetFrame(0).GetMethod().Name));
Paste this into your event/method or whatever. It will popup a messagebox with the method-name which called your current method. In this case (from comments) it would've raised 2 messageBoxes saying TeacherScheduleForm for both.
I've saved this to my code-snippets.

How can i stop/resume a backgroundworker/recursive loop?

In the top of the form1 i added:
System.Threading.ManualResetEvent _busy = new System.Threading.ManualResetEvent(true);
And also in the top of the form1 added two flags:
bool pause;
bool resume;
Both of the flags are set to false in the constructor.
Then i have a function that is recursive loop:
private List<string> test(string url, int levels,DoWorkEventArgs eve)
{
if (pause == true)
{
_busy.Reset();
}
if (resume == true)
{
_busy.Set();
}
this.Invoke(new MethodInvoker(delegate { label3.Text = label3.Text = (Int32.Parse(label12.Text) + Int32.Parse(label10.Text)).ToString(); }));
HtmlWeb hw = new HtmlWeb();
List<string> webSites;
List<string> csFiles = new List<string>();
csFiles.Add("temp string to know that something is happening in level = " + levels.ToString());
csFiles.Add("current site name in this level is : " + url);
try
{
this.Invoke(new MethodInvoker(delegate { ColorText.Texts(richTextBox1, "Loading The Url: " , Color.Red); }));
this.Invoke(new MethodInvoker(delegate { ColorText.Texts(richTextBox1, url + "...",Color.Blue); }));
HtmlAgilityPack.HtmlDocument doc = TimeOut.getHtmlDocumentWebClient(url, false, "", 0, "", "");
this.Invoke(new MethodInvoker(delegate { ColorText.Texts(richTextBox1, " Done " + Environment.NewLine, Color.Red); }));
currentCrawlingSite.Add(url);
webSites = getLinks(doc);
removeDupes(webSites);
removeDuplicates(webSites, currentCrawlingSite);
removeDuplicates(webSites, sitesToCrawl);
if (removeExt == true)
{
for (int i = 0; i < webSites.Count; i++)
{
webSites.Remove(removeExternals(webSites));
}
}
if (downLoadImages == true)
{
webContent.retrieveImages(url); }
if (levels > 0)
sitesToCrawl.AddRange(webSites
this.Invoke(new MethodInvoker(delegate { label7.Text = sitesToCrawl.Count.ToString(); }));
this.Invoke(new MethodInvoker(delegate { label12.Text = currentCrawlingSite.Count.ToString(); }));
if (levels == 0)
{
return csFiles;
}
else
{
for (int i = 0; i < webSites.Count(); i++)//&& i < 20; i++) {
string t = webSites[i];
if ((t.StartsWith("http://") == true) || (t.StartsWith("https://") == true)) // replace this with future FilterJunkLinks function
{
csFiles.AddRange(test(t, levels - 1, eve));
}
}
return csFiles;
}
}
catch
{
failedUrls++;
this.Invoke(new MethodInvoker(delegate { label10.Text = failedUrls.ToString(); }));
this.Invoke(new MethodInvoker(delegate { ColorText.Texts(richTextBox1, " Failed " + Environment.NewLine, Color.Green); }));
return csFiles;
}
}
In the backgroundworker DoWork event i added this:
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
_busy.WaitOne();
this.Invoke(new MethodInvoker(delegate { label2.Text = "Website To Crawl: "; }));
this.Invoke(new MethodInvoker(delegate { label4.Text = mainUrl; }));
test(mainUrl, levelsToCrawl, e);
}
Then i have two buttons click events one for pause one for resume:
private void button4_Click(object sender, EventArgs e)
{
pause = true;
}
private void button5_Click(object sender, EventArgs e)
{
resume = true;
}
But when i click on the button pause nothing happens either on the resume button. The process is keep going on. I tried also without flags just in each button to make _busy.Reset(); and _busy.Set(); but nothing.
What i want is to pause somehow the recursive loop and to resume it. Im not sure if its connected to the backgroundworker or not but the idea is to pause and resume the process.
What should i do ?
Thanks.

_busy.WaitOne();
That's the statement that would cause the worker to pause. However, it only appears at the start of DoWork(), where the event will never be reset yet. You'll need to move it inside the loop.
The second bug, one you haven't run into yet, is that once you paused you can never resume again. Because the worker is not running anymore and won't be paying attention to the resume variable. Get rid of those variables, your Click event should directly call the Set() and Reset() methods.