Pass async Callback to Timer constructor: How and Why?

What is an async callback?

Before diving into the details, let’s briefly understand what an async callback is. In C#, an async callback is a method that can be executed asynchronously. It typically returns a Task or Task<T> object, allowing the caller to await its completion. This enables non-blocking execution and better utilization of system resources.

How to pass an async callback to the Timer constructor?

To pass an async callback to the Timer constructor, you need to follow a few steps. Let’s walk through them:

Step 1: Define an async callback method

First, you need to define a method that will serve as your async callback. This method should have the async modifier and return void or Task. For example:

private async void HandleTimerCallback(object state)
    // Your async code here

Step 2: Create an instance of the Timer class

Next, create an instance of the Timer class and pass your async callback method as the first parameter to the constructor. You can also specify the time interval for the callback to be invoked as the second parameter. For example:

Timer timer = new Timer(HandleTimerCallback, null, TimeSpan.Zero, TimeSpan.FromSeconds(5));

In the above example, the HandleTimerCallback method will be invoked immediately (TimeSpan.Zero) and then every 5 seconds thereafter.

Step 3: Dispose the Timer object

To ensure proper cleanup and prevent resource leaks, it’s important to dispose of the Timer object when you’re done using it. You can do this by calling the Dispose method on the Timer instance or by using it within a using statement. For example:


Why pass an async callback to the Timer constructor?

Now that we know how to pass an async callback to the Timer constructor, let’s discuss why it can be a useful approach in certain scenarios.

Asynchronous execution

By using an async callback with the Timer class, you can execute code asynchronously at regular intervals. This is particularly useful when dealing with long-running or I/O-bound operations. Instead of blocking the main thread, you can offload the work to a separate thread or thread pool, allowing your application to remain responsive.

Better resource utilization

Using async callbacks with the Timer class can help improve resource utilization in your application. By executing code asynchronously, you can avoid blocking threads and free them up to perform other tasks. This can lead to better overall performance and scalability, especially in scenarios where multiple timers are involved.

Exception handling

One common concern with async callbacks is exception handling. When using async void methods, exceptions can be challenging to handle, as they don’t propagate back to the caller. However, in the case of the Timer class, exceptions escaping the async callback method are raised on a thread pool thread. This behavior is similar to synchronous methods and allows for proper exception handling.

Remember to dispose of the Timer object when you’re done using it to prevent resource leaks. Happy coding!

Categories C#

Related Posts

How to Post an Empty Body to REST API via HttpClient in C When working with REST APIs in C#, you may come across scenarios where you need to send a POST request with an empty body. This can be useful in situations where the API endpoint expects a POST request but doesn’t require any ...

Read more

Does C# have IsNullOrEmpty for List/IEnumerable?

If you’ve been working with C# for a while, you may have come across situations where you need to check if a List or IEnumerable is null or empty. In some other languages, like JavaScript, you have the convenience of using the Array.isArray() method or the length property to check if an array is empty ...

Read more

List Queries: 20 Times Faster than IQueryable?

Have you ever wondered why list queries are often faster than IQueryable queries in C#? In this article, we will explore the reasons behind this performance difference and discuss when and how to use each type of query. What is IQueryable? Before we dive into the performance comparison, let’s first understand what IQueryable is. IQueryable ...

Read more

Passing Different Number of Arguments to a Params Method at Runtime

How to Pass a Different Number of Arguments Using a List and Converting to an Array One way to pass a different number of arguments to a params method at runtime is by using a List<object> to store the arguments and then converting it to an array using the ToArray() method. Here’s an example: List<object> ...

Read more

Leave a Comment