In this paper, the expression "production systems" refers to flow-shops, job-shops, assembly systems, Kanban systems and, in general, to any Discrete Event System (DES) which transforms raw material and/or components into products and/or components. Such a system is said to be cyclic if it provides indefinitely the same sequence of products. A schedule of a cyclic production system is defined as soon as the starting time of each operation on the related resource is known. It has been showed that, whatever the feasible schedule applied to the cyclic production system, it is always possible to fully utilize the bottleneck resource. In other words, it is always possible to maximize the productivity of such a system. As a consequence, we aim at finding the schedule which permits to maximize the productivity with a Work-In-Process (WIP) as small as possible. We propose a heuristic approach based on Petri nets to find a near-optimal, if not optimal, solution. We also give a sufficient condition for a solution to be optimal.