Question

Consider the following code:

static void AddItem()
{
    lock (_list) 
        _list.Add ("Item " + _list.Count); //Lock 1

    string[] items;
    lock (_list) 
        items = _list.ToArray(); //Lock 2
    foreach (string s in items) 
        Console.WriteLine (s);
}

If Thread A gets Lock 2, and Thread B attempts to get Lock 1, will B get the lock or not? Considering both locks use the same locking object.

Answer 1

No, thread B will need to wait until thread A releases the lock. That’s the point of it being the same lock object, after all – there’s one lock. Where the lock is acquired or released is irrelevant: only one thread can “own” the monitor at a time.

I would strongly advise you to use braces for readability, by the way:

lock(_list)
{
    _list.Add(...);
}