Unexpected Behavior When Using BackgroundWorker with WinForms and CancellationToken
I'm wondering if anyone has experience with I've been working on this all day and I've encountered a strange issue with I'm developing a WinForms application that processes a large dataset in the background using `BackgroundWorker` to keep the UI responsive..... However, I'm encountering unexpected behavior when trying to implement cancellation via `CancellationToken`. After starting the `BackgroundWorker`, I pass a `CancellationToken` to the worker method and use it to check for cancellation. The issue arises when I attempt to cancel the operation; the worker doesn't seem to stop immediately, and I'm left with inconsistent UI states. Here's a simplified version of what I have: ```csharp private BackgroundWorker backgroundWorker; private CancellationTokenSource cancellationTokenSource; public MyForm() { InitializeComponent(); backgroundWorker = new BackgroundWorker(); backgroundWorker.DoWork += BackgroundWorker_DoWork; backgroundWorker.RunWorkerCompleted += BackgroundWorker_RunWorkerCompleted; cancellationTokenSource = new CancellationTokenSource(); } private void StartButton_Click(object sender, EventArgs e) { if (!backgroundWorker.IsBusy) { backgroundWorker.RunWorkerAsync(cancellationTokenSource.Token); } } private void CancelButton_Click(object sender, EventArgs e) { cancellationTokenSource.Cancel(); } private void BackgroundWorker_DoWork(object sender, DoWorkEventArgs e) { var token = (CancellationToken)e.Argument; for (int i = 0; i < 100; i++) { if (token.IsCancellationRequested) { e.Cancel = true; return; } // Simulate work System.Threading.Thread.Sleep(100); } } private void BackgroundWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) { if (e.Cancelled) { MessageBox.Show("Operation was cancelled."); } else { MessageBox.Show("Operation completed successfully."); } } ``` When I click the cancel button, the UI does not reflect that the operation has been canceled immediately, and in some cases, the `RunWorkerCompleted` event is not triggered at all. I’ve tried setting `e.Cancel = true` in the `DoWork` method, but it doesn't appear to be effective. Is there something I'm missing in the way `BackgroundWorker` interacts with `CancellationToken`? Any suggestions would be appreciated! This is part of a larger CLI tool I'm building. Any help would be greatly appreciated! For reference, this is a production desktop app. I'm working on a desktop app that needs to handle this. Any advice would be much appreciated. What's the correct way to implement this?