Currently, this stat reflects the number of "LockedClients" that the LockedClientsCursor finds (it even counts Clients in lock state kInactive). This means it includes all the internal Clients that are used by system threads, and it has only a loose connection to the stats that appear right afterwards, "globalLock.activeClients.readers" and "globalLock.activeClients.writers", since the total also includes queued reader and writers as well as inactive Clients.