async/await in C#

async/await syntax should be used for I/O bound asynchronous operations only.

public async Task<int> GetUrlContentLengthAsync()
{
    var client = new HttpClient();

    Task<string> getStringTask =
        client.GetStringAsync("https://docs.microsoft.com/dotnet");

    DoIndependentWork();

    string contents = await getStringTask;

    return contents.Length;
}

Compiler transforms code into a state machine that to track yielding execution for await and resuming execution when a background job is finished.

Things to keep in mind:

• async method needs await
• add Async suffix to asynchronous methods
• async void for ‘Fire and Forget’ work i.e. event Handlers
• be aware of mixing LINQ with async lambdas
• wait for tasks in a non-blocking manner (do not use Task.Result i.e.)
• for tight loops use ValueTasks
• Consider using ConfigureAwait(false) for performance and for avoiding deadlocks

Further read:

https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/concepts/async/task-asynchronous-programming-model