While reading the paper (I did find it very readable. Okay, I am a computer geek. Fair warning.) I noticed that Bigtable, which is a highly scallable distributed database (not relational), used a “lock service” called Chubby. What is a “lock service”? Well, the The Chubby Lock Service for Loosely-Coupled Distributed Systems paper will tell you. I am currently reading this paper. (Again, this is from 2006! Where have I been?) Mike Burrows, the author of The Chubby Lock Service for Loosely-Coupled Distributed Systems, sprinkles humor into a computer science paper discussing Paxos, “a family of protocols for solving consensus in a network of unreliable processors”. What I found interesting is how the “lock service” is used to share information in a highly distributed system. The Bigtable implementation is a client of the “lock service” and uses it to elect a leader; the leader is the node that aquires the lock–only one node will get the lock. The “lock service” can also store small amounts of information, like metadata or configuration information, that a client application can read from the “lock service”.

Next up is the paper Paxos Made Live – An Engineering Perspective. This paper provides some details on how the Google team implemented Chubby, some of the history of the previous implementation, and some of the issues that they discovered implementation the Paxos algorithm.

Together, these papers provide some details of how Google has implemented highly distributed systems. So far, the information about Paxos has been very enlightening. And I am impressed with the way in which a “lock service” is used to coordinate communication and direct cooperation in a automated distributed network. It seems that they have created simple building blocks that together work in sometimes unique ways to make a complex system.