Atomic operations on NUMA architectures are much more efficient than lock/unlock on the same memory. It's more expensive than no synchronization, but it's the

Atomic operations on NUMA architectures are much more efficient than lock/unlock on the same memory. It's more expensive than no synchronization, but it's the cheapest (that I know of) method of syncing state across threads and multiple CPU architectures. The only thing cheaper is immutable structures, but those obviously limit your ability to change state across threads.