asp.net mvc - Why do you use async if you don't promote it to the controller? -

i'm trying figure out how use async/await in c# in asp.net mvc. main point seems helps asp.net releasing threads worker pool when doing io (so can process other stuff). doing have promote async/await modifier method doing io call controller action (you better have few layers).

is there point in using feature without promoting async/await controller ? (by adding task.wait after call async method instance).

the answer yes think using task.wait in action not idea because can lead dead lock situation

consider guide :)

async/await best practice

where

figure 3 common deadlock problem when blocking on async code

public static class deadlockdemo {    private static async task delayasync()    {       await task.delay(1000);    }    // method causes deadlock when called in gui or asp.net context.    public static void test()    {        // start delay.        var delaytask = delayasync();        // wait delay complete.        delaytask.wait();    } } 

but if add configureawait(false) delayasync() this

await task.delay(1000).configureawait(false) 

then can avoid dead lock said in article

aside performance, configureawait has important aspect: can avoid deadlocks. consider figure 3 again; if add “configureawait(false)” line of code in delayasync, deadlock avoided. time, when await completes, attempts execute remainder of async method within thread pool context. method able complete, completes returned task, , there’s no deadlock. technique particularly useful if need gradually convert application synchronous asynchronous.