1. A method of controlling access to a shared data processing resource in a data processing system, the method comprising the steps of: predicting future utilization of the shared data processing resource based upon a rate of change of utilization of the shared data processing resource determined from historical utilization of the shared data processing resource over a predefined number of events or predetermined time intervals; and notifying users of the shared data processing resource of a potential future shortage of the shared data processing resource by setting a critical flag if the current utilization of the shared resource reaches a predefined maximum utilization value, and by setting a constraint flag if said step of predicting predicts that the utilization of shared data processing resource will be greater than the predefined maximum utilization value of the shared resource.