using System;

using System.Linq;

using System.Threading.Tasks;

using System.Collections.Generic;

public class Program

{

    public async void Main()

    {

        var data = new Data();

        Console.WriteLine("Main called");

        var tasks = new List<Task>();

        for( int i = 0; i < 5; i++ )

        {

            tasks.Add(data.Fire());

        }

        Console.WriteLine("Main working");

        System.Threading.Thread.Sleep(20);

        await ReleaseAsync(tasks);

        foreach( var task in tasks )

        {

            await task;

        }

        Console.WriteLine("Main ending");

    }

​

    public async Task ReleaseAsync(List<Task> TaskList)

    {

        var taskSet = new HashSet<Task>(TaskList);

        while (taskSet.Any()) taskSet.Remove(await Task.WhenAny(taskSet));

    }

    public async Task ReleaseAsync(params Task[] TaskArray)

    {

        var taskSet = new HashSet<Task>(TaskArray);

        while (taskSet.Any()) taskSet.Remove(await Task.WhenAny(taskSet));

    }

}

​

public class Data

{

    public async Task<int> Fire()

    {

        using( var db = new Context() )

        {

            return await db.Working();

        }

    }

}

​

public class Context : IDisposable

{

    public Context()

    {

        Console.WriteLine("open");

    }

    public async Task<int> Working()

    {

        return await Task.Run(() => {

            Console.WriteLine("work started");

            System.Threading.Thread.Sleep(20);

            throw new Exception("work broke");

            Console.WriteLine("work complete");

            return 5;

        });

    }

​

    public void Dispose()

    {

        Console.WriteLine("dispose");

    }

}