C # - using listbox.BeginUpdate / listbox.EndUpdate in multi-threaded environment not working

Question

My task is fully completed, with the exception of one problem. I am trying to control the updating of the ui list through beginupdate () and endupdate () through the backgroundWorker thread, which is also used to update my progress bar. I thought that locking or a monitor in the list of elements would be enough (in the case when the list needs to be parsed when drawing), but to no avail. Does anyone have any ideas?

Here's the corresponding code ...

EDIT: show adding items to the list through another thread.

private void backgroundWorker4_DoWork(object sender, DoWorkEventArgs e)
    {
        // Get the BackgroundWorker that raised this event.
        BackgroundWorker worker = sender as BackgroundWorker;

        // Number of intervals
        int stop = 60;

        for (int i = 1; i <= stop; i++)
        {
            if (worker.CancellationPending)
            {
                e.Cancel = true;
                backgroundWorker4.ReportProgress(0);
                return;
            }

            //listBoxBeginUpdate(listBox1);

            // Half second intervals
            //listBox1.BeginUpdate();
            //listBox1.EndUpdate();
            //ListBox.listBoxBeginUpdate(listBox1); 
            listBoxBeginUpdate(listBox1);
            Thread.Sleep(500);
            listBoxEndUpdate(listBox1);

            listBoxBeginUpdate(listBox1);
            Thread.Sleep(500);
            listBoxEndUpdate(listBox1);

            // Update every second
            //listBoxEndUpdate(listBox1);

            int progress = i * 100 / stop;
            backgroundWorker4.ReportProgress(progress);

            //updateProgressBar = !updateProgressBar;
        }
    }
public static void listBoxBeginUpdate(System.Windows.Forms.ListBox varListBox)
    {
        if (varListBox.InvokeRequired)
        {
            varListBox.BeginInvoke(new MethodInvoker(() => listBoxBeginUpdate(varListBox)));
        }
        else
        {
            // Request the lock, and block until it is obtained.
            Monitor.Enter(varListBox);
            try
            {
                // When the lock is obtained, add an element.
                varListBox.BeginUpdate();
            }
            finally
            {
                // Ensure that the lock is released.
                Monitor.Exit(varListBox);
            }
        }
    }

    public static void listBoxEndUpdate(System.Windows.Forms.ListBox varListBox)
    {
        if (varListBox.InvokeRequired)
        {
            varListBox.BeginInvoke(new MethodInvoker(() => listBoxEndUpdate(varListBox)));
        }
        else
        {
              // Request the lock, and block until it is obtained.
              Monitor.Enter(varListBox);
              try
              {
                 // When the lock is obtained, add an element.
                  varListBox.EndUpdate();
              }
              finally
              {
                 // Ensure that the lock is released.
                  Monitor.Exit(varListBox);
              }

            //lock (varListBox.Items)
            //{
            //    Monitor.Enter(varList
            //    varListBox.EndUpdate();
            //}
        }
    }

// Added to show the thread adding items into the list
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
    {
        // Get the BackgroundWorker that raised this event.
        BackgroundWorker worker = sender as BackgroundWorker;
        Random random = new Random();

        //Stopwatch stopwatch = new Stopwatch();
        //stopwatch.Start();

        while(_threadsRunning)
        {
            if (worker.CancellationPending)
            {
                e.Cancel = true;
                return;
            }

            System.Threading.Thread.Sleep(1000);

            int numberOfItems = random.Next(5, 10);
            for (int i = 5; i < numberOfItems; i++)
            {
                int number = random.Next(1, 10000);
                listBoxAddItem(listBox1, number);
            }

            backgroundWorker1.ReportProgress(numberOfItems);
        }
    }

public static void listBoxAddItem(System.Windows.Forms.ListBox varListBox, int item)
    {
        if (varListBox.InvokeRequired)
        {
            varListBox.BeginInvoke(new MethodInvoker(() => listBoxAddItem(varListBox, item)));
        }
        else
        {
            varListBox.Items.Add(item);
        }
    }

Answer 1

. backgroundWorker1, , , , ( Control.BeginInvoke), ListBox. backgroundWorker4 , , BeginUpdate EndUpdate.

• . , , , . , , , . , .

• BeginUpdate, EndUpdate Add . , , .

• ( Monitor.Enter Monitor.Exit) . - , .

• Control.BeginInvoke Control.Invoke . , argumentum ad populum. ( System.Windows.Forms.Timer), .