Await Task vs. Task.Result: What's the Difference?

await Task<t></t> vs. Task<t>.Result</t> in Asynchronous Programming

Understanding the core difference between await Task<t></t> and Task<t>.Result</t> is paramount for effective asynchronous programming. Let's illustrate this with a practical example.

Consider this method:

public async Task<string> GetName(int id)
{
    Task<string> nameTask = Task.Factory.StartNew(() => string.Format("Name matching id {0} = Developer", id));
    return nameTask.Result;
}

Here, Task<t>.Result</t> is used to retrieve the task's outcome. However, this approach can severely impact concurrency because it forces the calling thread to wait synchronously for task completion.

Asynchronous programming elegantly solves this using the await operator, which allows for non-blocking suspension. Here's the improved, asynchronous version:

public async Task<string> GetName(int id)
{
    Task<string> nameTask = Task.Factory.StartNew(() => string.Format("Name matching id {0} = Developer", id));
    return await nameTask;
}

With await, the calling thread is released, allowing other tasks to proceed. Once the awaited task finishes, the thread resumes, and the result is returned seamlessly.

In essence: await Task<t></t> facilitates true asynchronous operation by yielding the thread, while Task<t>.Result</t> blocks the thread until the task finishes. A crucial distinction is how exceptions are handled: Result wraps exceptions within AggregateException, whereas await re-throws the original exception directly.

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