An apparatus for maintaining a limit value of a resource for use in a concurrent limit checking system comprising: a resource having an associated limit value; a plurality of request handlers having access to a plurality of sub-limit values, wherein the sub-limit values when summed equal the limit value and wherein each request handler is operable to check a request value of a request for consuming the resource against its associated sub-limit value, in order to determine whether the request can be satisfied. The apparatus comprises a coordinator, responsive to the first request handler determining that the first request cannot be satisfied, for generating a coordination request comprising a coordination request value required to satisfy the first request, a receiver for receiving a coordination response from the second request handler; and an updater for updating the sub-limit values in accordance with the coordination request value.