C# – How to unit test async methods

Let’s say you have the following async method you want to test: Here’s how to unit test this: This is awaiting the method you’re testing. To await it, you must make the unit test method return async Task. This example is a bit simplistic. In the real world when you are working with async methods, … Read more C# – How to unit test async methods

C# – Use SemaphoreSlim for throttling threads

When you have multiple threads trying to do work at the same time, and you want to throttle how many of them are actually executing, you can use SemaphoreSlim. Example – a busy grocery store Grocery stores have a limited number of checkout lanes open. Let’s say the grocery store has two lanes open, and … Read more C# – Use SemaphoreSlim for throttling threads

Fixing the Sync over Async antipattern

The Sync over Async antipattern is when you’re using a blocking wait on an async method, instead of awaiting the results asynchronously. This wastes the thread, causes unresponsiveness (if called from the UI), and exposes you to potential deadlocks. There are two causes: Calling Wait() on the Task returned by the async call. Using Task.Result. … Read more Fixing the Sync over Async antipattern

Multithreaded quicksort in C#

One day I decided to challenge myself by trying to implement multithreaded quicksort. I wanted to see how it would compare to the built-in sort function – Array.Sort(). I came up with two algorithms that were 2-4x faster than Array.Sort(): Top-down: divide-fork-sort-merge Bottom-up: quicksort with fork-on-recursion After continuing to tinker, in attempts to further optimize, … Read more Multithreaded quicksort in C#

How to set a timeout for TcpClient.ConnectAsync()

TcpClient has no direct way to set the connection timeout. It doesn’t have any parameters that allow you to control it, and SendTimeout / ReceiveTimeout don’t apply to the initial connection. The way I control the connection timeout is by awaiting a Task.WhenAny() with TcpClient.ConnectAsync() and Task.Delay(). Task.WhenAny() returns when any of the tasks complete. … Read more How to set a timeout for TcpClient.ConnectAsync()