Chubby Lock Service service provides the ability over Asynchronous Operation and allows its clients to Replication of their activities and to achieve Consensus on basic information about their environment.
Chubby Lock Service allows the election of a master and to allow the master to discover the servers it controls, and to permit clients to find the master.
While this could be done with a library that provides Distributed Consensus, a lock server makes it easier to maintain existing program structure and communication patterns.