Pessimistic locking prevents conflicts that may arise when multiple users attempt to update the same resources.
The add-on automatically locks an entity instance when it is opened in the detail view. As a result, only one user can edit this particular entity instance in a given moment.
The pessimistic locking mechanism can also be used to manage simultaneous execution of arbitrary processes. The locks are distributed, since they are replicated in the cluster.
The add-on also provides a UI view where you can track the current state of locks and unlock any object if needed.