Just-in-Time Paxos

I was cleaning out my GitHub repos the other day when I stumbled across this old gem I’d long forgotten, and I thought I’d share it. When I was at the Open Networking Foundation, I did some research developing a low-latency consensus algorithm that achieves consensus in a single round trip in the normal case using an SDN-enabled clock synchronization protocol to order changes, and falls back to a more traditional consensus protocol (largely derived from Viewstamped Replication) when network ordering fails. The protocol was inspired by NOPaxos and was an attempt to build upon that work by replacing its single-point-of-failure sequencer with a high precision clock synchronization protocol implemented with programmable network devices.

The repo is a TLA+ spec describing the JIT Paxos protocol. I feel it prudent to warn that this project was just an experiment to see if/how high-precision clock synchronization could enable new consensus algorithm. NOPaxos was an innovation in consensus with software-defined networks, and their work inspired me to see if I could take that innovation even further. IIRC the protocol still had at least one glaring performance issues when I left it (not to mention the obvious issue that low latency can only be maintained with low concurrency). But nevertheless, there seems to be some interest in this work on Twitter, so I thought I’d share it here as well.

Perhaps my work can inspire someone to think outside the box and take consensus to the next level, as NOPaxos did for me.