An apparatus (5) manages resources of a resource-controlled system (1), e.g. data processing resources in a data processing system. The resource-controlled system (1) has resource-elasticity, namely it may operate in several states involving different amounts of system resources. The resource management apparatus (5) may select a modification action having at least one resource variation parameter. The resource variation parameter represents a resource quantity to be added or removed in the resource-controlled system (1). The apparatus (5) may update a value function of an adaptive learning agent (7) as a function of performance metrics (4) measured after the resources of the resource-controlled system have been modified by effecting the modification action. Responsive to a safety criterion not being fulfilled, a finer resource variation parameter may be substituted.