I am doing R&D on async and await for my project. What I have learned is that when async method is called, it frees the thread and let the thread to be used by others. We can set callback for await-able method using await keyword and that method returns value when the result is ready. If that happens:
- We should be able to access the
UIbriefly between operations. - Execution time should be faster than the usual synchronous method call.
In my case, I have no question about point 1, But for point 2, it's execution time seems same as the synchronous method call. For example see Sample Code 1 and Sample Output 1
Sample Code 1:
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Before Async Call");
AsyncMethod();
Console.WriteLine("After Async Call");
Console.ReadLine();
}
public async static void AsyncMethod()
{
var firstValue = FirstAsyncMethod("FirstAsyncMethod has been called");
Console.WriteLine("Middle of FirstAsyncMethod and SecondAsyncMethod");
var secondValue = SecondAsyncMethod("SecondAsyncMethod has been called");
Console.WriteLine(await firstValue);
Console.WriteLine(await secondValue);
}
public static async Task<string> FirstAsyncMethod(string value)
{
for (int i = 0; i < 500000000; i++)
{
i = i + 1 - 1;
}
return "Success: "+value;
}
public static async Task<string> SecondAsyncMethod(string value)
{
for (int i = 0; i < 500000000; i++)
{
i = i + 1 - 1;
}
return "Success: " + value;
}
}
Sample Output 1:
Before Async Call
Middle of FirstAsyncMethod and SecondAsyncMethod
Success: FirstAsyncMethod has been called
Success: SecondAsyncMethod has been called
After Async Call
But if I call the async method with Task.Run(()=> ) (For example Sample Code 2 and Sample Output 2), it reduces the execution time compared to first example (Sample Code 1).
Sample Code 2:
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Before Async Call");
AsyncMethod();
Console.WriteLine("After Async Call");
Console.ReadLine();
}
public async static void AsyncMethod()
{
var firstValue =Task.Run(()=> FirstAsyncMethod("FirstAsyncMethod has been called"));
Console.WriteLine("Middle of FirstAsyncMethod and SecondAsyncMethod");
var secondValue = Task.Run(() => SecondAsyncMethod("SecondAsyncMethod has been called"));
Console.WriteLine(await firstValue);
Console.WriteLine(await secondValue);
}
public static async Task<string> FirstAsyncMethod(string value)
{
for (int i = 0; i < 500000000; i++)
{
i = i + 1 - 1;
}
return "Success: "+value;
}
public static async Task<string> SecondAsyncMethod(string value)
{
for (int i = 0; i < 500000000; i++)
{
i = i + 1 - 1;
}
return "Success: " + value;
}
}
Sample Output 2:
Before Async Call
Middle of FirstAsyncMethod and SecondAsyncMethod
After Async Call
Success: FirstAsyncMethod has been called
Success: SecondAsyncMethod has been called
My question is, why the first example (Sample Code 1) taking time like synchronous method call?
