using System;

using System.Collections.Concurrent;

using System.Linq;

using System.Threading.Tasks;

public class Program

{

    private static readonly Random Random = new Random();

    public static async Task Main()

    {

        var tasks = Enumerable.Range(0, 100)

            .Select(_ => DoWork())

            .ToArray();

​

        await Task.WhenAll(tasks);

    }

    public static async Task<int> DoWork()

    {

        await Task.Delay(1000);

        if (Random.Next() % 2 == 0)

        {

            throw new Exception("Exception occured");

        }

        return Random.Next();

    }

}