How to Safely Implement 'Fire and Forget' Asynchronous Methods in ASP.NET MVC?

Safely handle fire-and-forget in ASP.NET MVC asynchronous methods

While the "fire and forget" approach is generally not recommended in ASP.NET applications, there may be situations where it is necessary to call an asynchronous method without waiting for it to complete. However, executing asynchronous methods in a fire-and-forget manner comes with certain risks and limitations.

One risk is that unhandled exceptions in async methods will go unnoticed and may lead to unexpected behavior. To solve this problem, it is recommended to subscribe to TaskScheduler.UnobservedTaskException events to log exceptions and prevent them from causing the application to crash.

Another option is to create a wrapper method that handles the exception in the async method like this:

<code class="language-csharp">private async Task DeleteFooWrapperAsync()
{
    try
    {
        await DeleteFooAsync();
    }
    catch(Exception exception )
    {
        m_log.Error("DeleteFooAsync failed: " + exception.ToString());
    }
}</code>

However, be aware that wrapping each async method with a try-catch block can become verbose and repetitive.

Another approach is to use the ASP.NET runtime to register asynchronous work. Using Scott Hanselman's BackgroundTaskManager library you can execute tasks concurrently and centrally log exceptions:

<code class="language-csharp">BackgroundTaskManager.Run(() => DeleteFooAsync());</code>

This method registers the task with the runtime, allowing it to continue executing after the ASP.NET request completes while still catching exceptions.

Finally, if you really need to execute an asynchronous method in a fire-and-forget manner without exception handling, you can use Task.Run() to create a new thread for the asynchronous operation:

<code class="language-csharp">Task foo = Task.Run( () => DeleteFooAsync() );</code>

However, it is important to remember that fire-and-forget should only be used if you can tolerate the potential consequences of unhandled exceptions.

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