void ConcurrentDicTest()
{
    ConcurrentDictionary<string, string> concurrDic = new ConcurrentDictionary<string, string>();

    Task tsk1 = Task.Factory.StartNew(() =>
    {
        for (int i = 0; i < 100; i++)
        {
            concurrDic.TryAdd(i.ToString(), (i + i).ToString());
            Thread.Sleep(100);
        }
    });

    Task tsk2 = Task.Factory.StartNew(() =>
    {
        Thread.Sleep(300);
        foreach (var item in concurrDic)
        {
            Console.WriteLine($"{item.Key} - {item.Value}");
            Thread.Sleep(150);
        }
    });

    try
    {
        Task.WaitAll(tsk1, tsk2);
    }
    catch (AggregateException agExc)
    {
        Console.WriteLine(agExc.Flatten().Message);
    }
}