1. A deadlock detection system in a data processor in which a plurality of resources are shared among a plurality of resource requesters, the deadlock detection system comprising: a lock control table for listing resource identities; a resource requester identifier list to each entry of said lock control table, for listing one or more resource requester identifiers in association with respective resource identities stored in the lock control table, the one or more resource requester identifiers being listed sequentially in a requesting order in which a leading resource requester identifier corresponding to a leading resource requester, can obtain an exclusive lock on a respective resource; and lock control means for examining the lock control table and the resource requester identifier list, to determine whether a deadlock exists in which a group of resource requester identifiers which are leading resource requester identifiers for respective resources, are listed in respective requesting orders with resource requester identifiers of the group, which are not leading resource requester identifiers, and in which at least one of the leading resource requester identifiers in the group and at least one of the resource requester identifiers in the group which is not a leading resource requester identifier, are not identical for at least one requesting order, the lock control means performing control of the exclusive lock of the respective resource, based on whether the deadlock exists.