Henry Robinson (henry at apache dot org)
Java and TCP/IP networking
When a ZooKeeper server loses contact with over half of the other servers in an ensemble ('loses a quorum'), it stops responding to client requests because it cannot guarantee that writes will get processed correctly. For some applications, it would be beneficial if a server still responded to read requests when the quorum is lost, but caused an error condition when a write request was attempted.
This project would implement a 'read-only' mode for ZooKeeper servers (maybe only for Observers) that allowed read requests to be served as long as the client can contact a server.
This is a great project for getting really hands-on with the internals of ZooKeeper - you must be comfortable with Java and networking otherwise you'll have a hard time coming up to speed.