Does the use of async/await create a new thread?

c# multithreading async-await task-parallel-library c#-5.0
dev hedgehog picture dev hedgehog · Dec 3, 2014 · Viewed 33.3k times · Source

I am new to TPL and I am wondering: How does the asynchronous programming support that is new to C# 5.0 (via the new async and await keywords) relate to the creation of threads?

Specifically, does the use of async/await create a new thread each time that they are used? And if there many nested methods that use async/await, is a new thread created for each of those methods?

Answer

Adriaan Stander picture Adriaan Stander · Dec 3, 2014

In short NO

From Asynchronous Programming with Async and Await : Threads

The async and await keywords don't cause additional threads to be created. Async methods don't require multithreading because an async method doesn't run on its own thread. The method runs on the current synchronization context and uses time on the thread only when the method is active. You can use Task.Run to move CPU-bound work to a background thread, but a background thread doesn't help with a process that's just waiting for results to become available.

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