How to Execute Background Tasks in WPF Applications Without Freezing the UI?

Execute Background Tasks in WPF Applications

In WPF applications, it's often necessary to perform tasks in the background to avoid freezing the user interface (UI). To do this, developers need a mechanism that meets the following criteria:

• Non-blocking UI thread
• Progress reporting
• Cancellation
• Multithreading support

Recommended Approach: Task-based API and Async/Await

With the release of .NET 4.5 (or .NET 4.0 with the Microsoft.Bcl.Async library), the recommended approach for background tasks is to utilize the Task-based API and async/await. This technique offers the following advantages:

• Pseudo-sequential code workflow: Developers can write code that reads like a sequential workflow, making it easier to understand and maintain.
• Structured exception handling: Async/await provides a structured way to handle asynchronous exceptions.

Example Implementation

The following code demonstrates how to execute a background task using the Task-based API and async/await:

private async void Start(object sender, RoutedEventArgs e)
{
    try
    {
        await Task.Run(() =>
        {
            int progress = 0;
            for (; ; )
            {
                System.Threading.Thread.Sleep(1);
                progress++;
                Logger.Info(progress);
            }
        });
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }
}

This code spawns a new task in parallel to the UI thread, allowing the UI to remain responsive while the background task progresses. It also includes exception handling to display an error message if an exception occurs during task execution.

Additional Resources

For more information on executing background tasks in WPF with progress reporting and cancellation support, consider the following references:

• [How to execute task in the WPF background while able to provide report and allow cancellation?](https://stackoverflow.com/questions/12342842/how-to-execute-task-in-the-wpf-background-while-able-to-provide-report-a)
• [Async in 4.5: Enabling Progress and Cancellation in Async APIs](https://blogs.msdn.microsoft.com/charlie/2012/03/14/async-in-4-5-enabling-progress-and-cancellation-in-async-apis/)
• [Async and Await](https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/concepts/async/)
• [Async/Await FAQ](https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/concepts/async/async-faq)

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