问题
I know there is a difference between this code:
var streamWriter = new StreamWriter("something.txt");
streamWriter.WriteAsync("text");
and this:
var streamWriter = new StreamWriter("something.txt");
Task.Run(()=> streamWriter.Write("text"));
the first one makes much more sense.
and in different scenario when I am awaiting a result, this code:
var streamReader = new StreamReader("something.txt")
char[] chars = new char[10];
Task<int> task = streamReader.ReadAsync(chars, 0, chars.Length);
//Do something...
int num = await task;
//Do something with num...
makes much more sense than this:
var streamReader = new StreamReader("something.txt")
char[] chars = new char[10];
Task<int> task = Task.Run(()=>streamReader.Read(chars, 0, chars.Length));
//Do something...
int num = await task;
//Do something with num...
I guess the use of the built in async API is better not only in clarity and it actually manages the ThreadPool threads better and in more efficient way than having a ThreadPool thread waiting for no reason.
Is it right?
回答1:
A synchronous call wrapped in a Task.Run will block a thread pool thread for the duration of that operation. A truly asynchronous implementation will not.
With streams in particular, whether the operation is "truly asynchronous" can be a bit tricky to determine. For example, network streams are always truly asynchronous, memory streams are never truly asynchronous, and file streams are only truly asynchronous if you pass a special flag to their constructor.
来源：https://stackoverflow.com/questions/39669064/why-should-i-prefer-using-api-async-fucntions-over-wrapping-synchronous-ones-wit