async at console app in C

Question

I have this simple code    public static async Task lt int gt  SumTwoOperationsAsync         var firstTask   GetOperationOneAsync        var secondTask   GetOperationTwoAsync        return await firstTask   await secondTask      private async Task lt int gt  GetOperationOneAsync         await Task Delay 500      Just to simulate an operation taking time     return 10     private async Task lt int gt  GetOperationTwoAsync         await Task Delay 100      Just to simulate an operation taking time     return 5      Great  this compiles   But Lets say I have a console app and I want to run the code above   calling SumTwoOperationsAsync      static  void Main string   args                         SumTwoOperationsAsync                But I ve read that  when using sync  I have to sync all the way up and down      Question   So does this means that my Main function should be marked as async    Well it can t be because there is a compilation error      an entry point cannot be marked with the  async  modifier   If I understand the async stuff   the thread will enter the Main function ----  SumTwoOperationsAsync ---- will call both functions and  will be out  but until the SumTwoOperationsAsync  What am I missing

User · Accepted Answer

In most project types  your async  up  and  down  will end at an async void event handler or returning a Task to your framework   However  Console apps do not support this   You can either just do a Wait on the returned task   static void Main       MainAsync   Wait         or  if you want to avoid exceptions being wrapped into AggregateException        MainAsync   GetAwaiter   GetResult       static async Task MainAsync               or you can use your own context like the one I wrote   static void Main       AsyncContext Run      gt  MainAsync        static async Task MainAsync               More information for async Console apps is on my blog

User · Answer

Here is the simplest way to do this  static void Main string   args        Task t   MainAsync args       t Wait       static async Task MainAsync string   args        await

User · Answer

My solution   The JSONServer is a class I wrote for running an HttpListener server in a console window   class Program       public static JSONServer srv   null       static void Main string   args                Console WriteLine  NLPS Core Server             srv   new JSONServer 100           srv Start             InputLoopProcessor             while srv IsRunning                        Thread Sleep 250                         private static async Task InputLoopProcessor                 string line                Console WriteLine  Core NLPS Server  Started on port 8080      DateTime Now            while line     quit                         Console Write                    line   Console ReadLine   ToLower                Console WriteLine line                if line           line     help                                 Console WriteLine  Core NLPS Server Help                    Console WriteLine        or help  Show this help                     Console WriteLine      quit  Stop the server                                     srv Stop            Console WriteLine  Core Processor done at     DateTime Now

User · Answer

As a quick and very scoped solution   Task Result  Both Task Result and Task Wait won t allow to improving scalability when used with I O  as they will cause the calling thread to stay blocked waiting for the I O to end      When you call  Result on an incomplete Task  the thread executing the method has to sit and wait for the task to complete  which blocks the thread from doing any other useful work in the meantime  This negates the benefit of the asynchronous nature of the task    notasync

[c#] async at console app in C#?

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