How does local initialization with Parallel ForEach work?

Question

I am unsure about the use of the local init function in Parallel.ForEach, as described in the msdn article: http://msdn.microsoft.com/en-us/library/dd997393.aspx

Answer 1

From my side a little bit more easier example

class Program
{
    class Person
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int Age { get; set; }
    }

    static List GetPerson() => new List()
    {
        new Person() { Id = 0, Name = "Artur", Age = 26 },
        new Person() { Id = 1, Name = "Edward", Age = 30 },
        new Person() { Id = 2, Name = "Krzysiek", Age = 67 },
        new Person() { Id = 3, Name = "Piotr", Age = 23 },
        new Person() { Id = 4, Name = "Adam", Age = 11 },
    };

    static void Main(string[] args)
    {
        List persons = GetPerson();
        int ageTotal = 0;

        Parallel.ForEach
        (
            persons,
            () => 0,
            (person, loopState, subtotal) => subtotal + person.Age,
            (subtotal) => Interlocked.Add(ref ageTotal, subtotal)
        );

        Console.WriteLine($"Age total: {ageTotal}");
        Console.ReadKey();
    }
}