Can ToArray() throw an exception?

Question

While the answer to this question is excellent, it implies that you should surround calls to List.ToArray() in a lock for concurrency. this blog post also implies that it c

Answer 1

When thread-safety is not explicitly guaranteed by the docs or by principle you cannot assume it. If you do assume it you risk putting a class of bugs into production that is undebuggable and has the potential to cost you a lot of productivity/availability/money. Are you willing to take that risk?

You can never test something to be threadsafe. You can never be sure. You cannot be sure that a future version behaves the same way.

Do it the right way and lock.

Btw, these remarks were for List.ToArray which is one of the more safe versions of ToArray. I understand why one would mistakenly think it can be used concurrently with writes to the list. Of course IEnumerable.ToArray cannot possibly be threadssafe because that is a property of the underlying sequence.