The foreach identifier and closures

Question

In the two following snippets, is the first one safe or must you do the second one?

By safe I mean is each thread guaranteed to call the method on the Foo from the s

Answer 1

This is an interesting question and it seems like we have seen people answer in all various ways. I was under the impression that the second way would be the only safe way. I whipped a real quick proof:

class Foo
{
    private int _id;
    public Foo(int id)
    {
        _id = id;
    }
    public void DoSomething()
    {
        Console.WriteLine(string.Format("Thread: {0} Id: {1}", Thread.CurrentThread.ManagedThreadId, this._id));
    }
}
class Program
{
    static void Main(string[] args)
    {
        var ListOfFoo = new List();
        ListOfFoo.Add(new Foo(1));
        ListOfFoo.Add(new Foo(2));
        ListOfFoo.Add(new Foo(3));
        ListOfFoo.Add(new Foo(4));


        var threads = new List();
        foreach (Foo f in ListOfFoo)
        {
            Thread thread = new Thread(() => f.DoSomething());
            threads.Add(thread);
            thread.Start();
        }
    }
}

if you run this you will see option 1 is definetly not safe.