Почему инициализация атрибута threadstatic в делегате Threadlocal не инициализирует его для первого потока? ⇐ C#

[Anonymous]

Я создал 3 потока, и все потоки имеют операцию увеличения атрибута threadlocal, кроме потока1. Я также инициализирую атрибут threadstatic в делегате threadlocal значением 11.
Здесь я всегда получаю значение num = 0 в первом потоке. Почему так?
class Program
{
//static int numDuplicate = 0;
[ThreadStatic]
static int num = 5;

public static ThreadLocal _field = new ThreadLocal(() =>
{
num = 11;
//numDuplicate = num;
Console.WriteLine("Threadstatic variable value in Threadlocal's delegate = " + num.ToString());
return Thread.CurrentThread.ManagedThreadId;
});

public static void Main(string[] args)
{
Thread t1 = new Thread(new ThreadStart(() =>
{
Console.WriteLine("Threadlocal attribute value for thread 1: " + _field + ". Threadstatic variable value = " + num.ToString());
}));

Thread t2 = new Thread(new ThreadStart(() =>
{
_field.Value++;
Console.WriteLine("Threadlocal attribute value for thread 2: " + _field + ". Threadstatic variable value = " + num.ToString());
}));

Thread t3 = new Thread(new ThreadStart(() =>
{
_field.Value++;
Console.WriteLine("Threadlocal attribute value for thread 3: " + _field + ". Threadstatic variable value = " + num.ToString());
}));

t1.Start();
t2.Start();
t3.Start();
Console.ReadLine();
}
}

//Output:
Threadstatic variable value in Threadlocal's delegate = 11
Threadstatic variable value in Threadlocal's delegate = 11
Threadstatic variable value in Threadlocal's delegate = 11
Threadlocal attribute value for thread 1: 10. Threadstatic variable value = 0
Threadlocal attribute value for thread 3: 13. Threadstatic variable value = 11
Threadlocal attribute value for thread 2: 12. Threadstatic variable value = 11


Подробнее здесь: https://stackoverflow.com/questions/412 ... t-initiliz