Jetpack: Consensus Made Generally Fast (OSDI '26)

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Aleksey and I are back to reading papers live. This paper, Jetpack(OSDI '26), attempts building a universal 1-RTT fast-path framework that bolts onto existing leader-based consensus protocols with minimal modification.Why would we want this? Classic consensus protocols like Raft, Paxos, or Zab require two round-trip times (2 RTT) to commit a command: one RTT from client to leader, and another to replicate across followers. The extra RTT matters a lot for WAN deployments, so fast-path protocols (such as Fast Paxos, EPaxos, or SwiftPaxos) reduce this to 1 RTT by bypassing leader serialization, but unfortunately they tightly couple the fast path to the core protocol design. Production systems cannot easily swap out their battle-tested bespoke consensus engines, but if there was an add on that helped with latency especially in WAN deployments, that would be useful.The good news is that Jetpack is truly an add-on portable deal. It provides a shim layer that runs two execution paths in parallel: a 1-RTT fast path and the original 2-RTT consensus path. When a client issues a command, it broadcasts the request concurrently to both paths. The fast path checks for key conflicts, and if none