Optimistic Lock Conflicts 

With regard to collisions a lock of type O behaves like a shared lock (S). This means, it collides with existing E and X locks (see Lock Collisions).

If an exclusive lock belonging to another owner exists, the optimistic lock cannot be set. It is irrelevant whether the write lock is a conventional E lock or a converted optimistic lock.

Optimistic locks belonging to different owners are compatible with one another. The first owner who converts the optimistic lock into an exclusive lock can actually change the data. The other optimistic locks become invalidated (deleted from the lock table). If you try to change them, the exclusive lock cannot be set.