Async in ASP.NET Core
async/await in controllers, CancellationToken, streaming responses, timeouts, async filters, IAsyncEnumerable
1Why use async/await in ASP.NET Core controller actions?
Why use async/await in ASP.NET Core controller actions?
답변
Using async/await in controllers frees thread pool threads during I/O operations (database, external APIs). This improves server scalability by allowing the thread to process other requests while waiting. Without async, the thread remains blocked and consumes resources unnecessarily, limiting the number of concurrent requests.
2What happens if a controller action returns Task<IActionResult> without using async/await?
What happens if a controller action returns Task<IActionResult> without using async/await?
답변
Returning Task<IActionResult> without async/await works if you directly return an existing Task (return dbContext.SaveChangesAsync();). However, without the async keyword, you cannot use await in the method body. Most of the time, using async allows awaiting multiple async operations and handling errors with try/catch.
3What is the difference between ToList() and ToListAsync() in a controller action?
What is the difference between ToList() and ToListAsync() in a controller action?
답변
ToList() is synchronous and blocks the thread during the database query, limiting scalability. ToListAsync() is asynchronous and frees the thread during I/O operations, allowing the server to process other requests. Always use ToListAsync() in controllers to maximize supported concurrent requests.
What is the role of CancellationToken in controller actions?
How to obtain the CancellationToken in an ASP.NET Core controller action?
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