c# - Why use async with QueueBackgroundWorkItem?

Question

What is the benefit of using async with the ASP.NET QueueBackgroundWorkItem method?

HostingEnvironment.QueueBackgroundWorkItem(async cancellationToken =>
{
    var result = await LongRunningMethodAsync();
    // etc.
});

My understanding is that async functions are used to prevent long-running tasks from blocking the main thread. However, in this case aren't we executing the task in its own thread anyway? What is the advantage over the non-async version:

HostingEnvironment.QueueBackgroundWorkItem(cancellationToken =>
{
    var result = LongRunningMethod();
    // etc.
}); 

Answer 1

What is the benefit of using async with the ASP.NET QueueBackgroundWorkItem method?

It allows your background work item to call asynchronous APIs.

My understanding is that async functions are used to prevent long-running tasks from blocking the main thread. However, in this case aren't we executing the task in its own thread anyway?

The advantage of async methods are that they free up the calling thread. There is no "main thread" on ASP.NET - just request threads and thread pool threads out of the box. In this case, an asynchronous background work item would free up a thread pool thread, which may increase scalability.

What is the advantage over the non-async version

Or, you could think of it this way: if LongRunningOperationAsync is a naturally asynchronous operation, then LongRunningOperation will block a thread that could otherwise be used for something else.