A robust and lightweight stable leader election service for dynamic systems

We describe the implementation and experimental evaluation of a fault-tolerant leader election service for dynamic systems. Intuitively, distributed applications can use this service to elect and maintain an operational leader for any group of processes which may dynamically change. If the leader of a group crashes, is temporarily disconnected, or voluntarily leaves the group, the service automatically re-elects a new group leader. The current version of the service implements two recent leader election algorithms, and users can select the one that fits their system better. Both algorithms ensure leader stability, a desirable feature that lacks in some other algorithms, but one is more robust in the face of extreme network disruptions, while the other is more scalable. The leader election service is flexible and easy to use. By using a stochastic failure detector and a link quality estimator, it provides some degree of QoS control and it adapts to changing network conditions. Our experimental evaluation indicates that it is also highly robust and inexpensive to run in practice.