Does the await automatically dispose the StreamReader resource in C#?

Question

Does it make sense to use the using pattern in this case? Or does await automatically dispose of this resource?

var payload = await new StreamReader(HttpContext.Request.Body).ReadToEndAsync();

Answer 1

No, and why would it?

Look at the whole StreamReader API - it i s not ONLY "ReadToEnd" - and even then, what if your code then RESETS the reader to a different position and reads more?

It would totally go against the API of a StreamReader to automatically dispose it and actively sabotage it in many use cases.

Also, it would make an async method behave different form the non-async version.

Ergo - no, it does make no sense for it to dispose, so it does not.

Answer 2

No, await does no such thing.

But it makes sense to wrap streams that your code creates in a using() { ... } or a try/finally block, Yes. However, if the stream was not "created" by your code then you should feel no obligation to dispose or close it.

You could easily do this:

using (StreamReader s = new StreamReader(HttpContext.Request.Body))
{
    var payload = await s.ReadToEndAsync();
}