.Net Threading – BeginInvoke uses the thread pool

For a while now I’ve been curious as to whether the CLR uses the ThreadPool to execute a delegate when BeginInvoke is called:

private void InvokeFunc(Func<int> func)
{
    func.BeginInvoke(null, null); // does this execute on a threadpool thread?
}

Whilst common sense dictates that this must surely be true, I couldn’t be certain since I haven’t managed to find any confirmation in the documentations.

Thanks to Jon Skeet and Jeff Sternal who provided the answer to my question and a link to the MSDN article which confirms it:

If the BeginInvoke method is called, the common language runtime (CLR) queues the request and returns immediately to the caller. The target method is called asynchronously on a thread from the thread pool.

This of course, means that if your delegate is likely to take a while to execute you should not call BeginInvoke on the delegate to avoid blocking the ThreadPool threads, instead you could create a new thread or use a SmartThreadPool instance. I’ve discussed these aspect in more detail here and here if you’re interested.

References:

MSDN – Asynchronous Programming using Delegates

StackOverflow Question – Does Func.BeginInvoke use the ThreadPool

Liked this article? Support me on Patreon and get direct help from me via a private Slack channel or 1-2-1 mentoring.
Subscribe to my newsletter


Hi, I’m Yan. I’m an AWS Serverless Hero and the author of Production-Ready Serverless.

I specialise in rapidly transitioning teams to serverless and building production-ready services on AWS.

Are you struggling with serverless or need guidance on best practices? Do you want someone to review your architecture and help you avoid costly mistakes down the line? Whatever the case, I’m here to help.

Hire me.


Check out my new course, Complete Guide to AWS Step Functions. In this course, we’ll cover everything you need to know to use AWS Step Functions service effectively. Including basic concepts, HTTP and event triggers, activities, callbacks, nested workflows, design patterns and best practices.

Get Your Copy