Which one the correct Fire and Forget?

Question

Which one the correct Fire and Forget?

winanjaya 146

Hi All,

I still confuse about async and await, I have a big and long process and I don't want to wait that process to finish.

which one of the following C# code is correct to do the Fire and Forget?

BigAndLongProcessAsync(); // just call the method without async?, but my understanding if without await it would become synchronus
Task.Run(async () => await BigAndLongProcessAsync()); // create a task to call async method with await

or

Task.Run(async () => BigAndLongProcessAsync()); // create task to call async method without await

internal async Task BigAndLongProcessAsync()
{ 
    // some big and long process with await inside
    // send email notification of each result of the process
}

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Answer 1

A few things:

You don't need the async on the method signature if there's no await in the body, so you can drop it from this:

Task.Run(async () => BigAndLongProcessAsync());

Calling BigAndLongProcessAsync(); without an await will result in all the synchronous code that's executed in BigAndLogProcessAsync to be run synchronously on the calling thread. If there's an await in this method, everything after that line will be executed asynchronously, in a fire-and-forget manner, on a new thread.
Calling your method in a Task.Run allows you to run the entire method (including the synchronous code that precedes the first await inside your method) on a separate thread.

Whether you use Task.Run depends on whether you want to offload the synchronous work to the separate thread immediately. This may not be ideal as that synchronous code may need to run on the main thread as that thread is the only one that has access to certain resources (e.g. the main thread in Winforms is the thread that you'll want to manipulate UI elements from), in which case your first example would be necessary.

Matteo Venturi 0 Reputation points

2024-12-10T10:10:08.2966667+00:00

The point 1 is not correct: calling BigAndLongProcessAsync without awaiting it will cause executing the code inside BigAndLongProcessAsync in a different thread, in the same time the caller thread will continue to execute own code. The result is the parallel execution of BigAndLongProcessAsync code and main code.

Answer 2

First of all, please note that the purpose of the async programming in the ASP.NET is to increase scalability unlike Windows desktop app. For details, see the following Microsoft document:

Async Programming : Introduction to Async/Await on ASP.NET

Second, please note that the ASP.NET app itself is async app as described in the above document.

Therefore, a use of Task.Run is one of things you have to avoid in the ASP.NET programming. For details, see the following Microsoft document:

ASP.NET Core Best Practices

As described on the above document, if BigAndLongProcessAsync() calls data access, I/O, and long-running operations APIs asynchronously, make controller/Razor Page actions asynchronous so that the entire call stack is asynchronous in order to benefit from async/await patterns.

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Which one the correct Fire and Forget?

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