Ytukyg

When I am using Task.run(), the console application is automatically stopping while creating a new SqlConnection(),
If I use normally Its working fine. I am unable to create a new connection in the console application.

namespace ConsoleApplication1

 {

  class Program

  {

    static void Main(string args)

    {

       new Program().startTAsk();

    }



    public async void startTAsk()

    {

           List<Task> tasks = new List<Task>();

        for (int i = 0; i < 1; i++)

        {

            tasks.Add(Task.Run(() => this.connectDB()));

        }



        await Task.WhenAll(tasks);



    }



    public void connectDB()

    {

        string dbDynamicConnectionString = "Data Source=192.168.1.20;Initial Catalog=Test;Persist Security Info=True;User ID=Test;Password=Test";

        bool ret = false;

        SqlConnection connection = null;

        try

        {

            using (connection = new SqlConnection(dbDynamicConnectionString))

            {



                //connect to db

            }

        }

        catch (Exception ex)

        {

              console.writeLine("exception");

        }





    }

}

}

This code has an obvious problem - it never waits for the task to complete and exits before it even starts.

There's nothing wrong with Task.Run to begin with, but it does start another thread. SqlClient offers true asynchronous methods though which don't take up a thread just to block it while waiting.

The code could be rewritten this way:

static async Task RunSomeCommand(string connString)

{

    try

    {

        using (var connection = new SqlConnection(connString))

        {

            var cmd=new SqlCommand(...);

            await connection.OpenAsync();

            await cmd.ExecuteNonQueryAsync();

        }

    }

    catch (Exception ex)

    {

          console.writeLine("exception");

    }

}   



static async Task RunManyCommands()

{

   var listOfConnections=new List<string>();

   //Somehow load all connection strings

   var tasks = from cn in listOfConnections

               select RunSomeCommand(cn);

   await Task.WhenAll(tasks);

}



class Program

{

   static async Task Main(string args)

   {

      Console.WriteLine("Starting");

      await RunManyCommands();

      Console.WriteLine("Finished");

   }

}

RunSomeCommand opens a connection and executes a command asynchronously. RunManyCommands starts multiple asynchronous operations and awaits all of them to complete. Finally Main itself awaits RunManyCommands to finish before terminating