CODEWITHSUNDEEP
c#.netasynchronous.net-coreasync-await
kord
kord

Reputation: 1039

Can the same thread be used by multiple web requests when one request is in an I/O-bound work state?

In .NET Core, let's say we have a web API endpoint which triggers an async/await operation because there is some I/O work to be done.

Since we're using async/await, the thread that handles this first request is freed up when I/O work starts.

What if that I/O work takes some time, all other threads are busy(thread pool is full) and a new request comes ? Is it possible for the freed up thread which normally waits for the I/O operation, to pickup work for the new request ?

Upvotes: 1

Views: 1817

Answers (1)

Stephen Cleary
Stephen Cleary

Reputation: 456677

Since we're using async/await, the thread that handles this first request is freed up when I/O work starts.

Yes. Once the top-level handler does an await, that request thread is returned to the thread pool.

What if that I/O work takes some time, all other threads are busy(thread pool is full) and a new request comes ?

If all the request threads are busy, then the request sits in a queue waiting for a free thread.

Is it possible for the freed up thread which normally waits for the I/O operation, to pickup work for the new request ?

It's not clear what you mean by this "thread which normally waits for the I/O operation". The I/O operation was asynchronous, so the request thread has been returned to the thread pool, and there is no thread waiting for the I/O operation.

You might find this article helpful; the details do not apply to ASP.NET Core, but the general concepts do (synchronous vs asynchronous requests, threads "doing" I/O, and thread pool vs async).

Upvotes: 3

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