When will Mendix have a feature of optimistic lock and/or pessimistic lock?
Mendix Entity does not support 'optimistic concurrency control' and 'pessimistic concurrency control' at all. Japanese largest system integrators always require optimistic lock or pessimistic lock; otherwise, they never buy Mendix. When will Mendix have a feature of 'optimistic lock' and/or 'pessimistic lock'?
I agree with you that since these are such common requirements there should have been some kind of out of the box support for it.
However, you can implement both yourself. Pessimistic locking is the easiest. Just add a revision number to every entity and check if a newer revision has been committed before committing a revision.
Optimistic locking is a lot harder to implement. No one has actually come up with a good way to do it, but in theory it is possible.