Time Semantics and Liveness Artifacts in Adversarial Consensus Simulation

2026-09-26

AI Summary

This study addresses liveness artifacts arising from the coupling of protocol time and schedulers in adversarial consensus simulations. Building upon the VeriProtocol framework, it investigates the Multi-Paxos and Raft algorithms by introducing a novel RoundTick mechanism that decouples scheduling events from time progression. Through controlled experiments, matching trajectory analysis, and heartbeat delay control techniques, extensive simulations are conducted. Results demonstrate that under the conventional EventCoupled model, increased message delays cause leader instability rates to surge from 5% to 100%, whereas RoundTick completely eliminates spurious elections under identical conditions. By precisely identifying and resolving false leader instability induced by communication scheduling, this work provides a more reliable temporal modeling methodology for distributed consensus verification.

Abstract

Adversarial consensus simulators require not only a model of message delivery but also a model of time. For timeout-sensitive protocols, coupling protocol-time progression to scheduler activity can allow communication scheduling to influence when failure detectors expire. We study this interaction in VeriProtocol using controlled Multi-Paxos and Raft experiments. In the primary Multi-Paxos study, we compare EventCoupled timing, where every scheduler opportunity advances protocol time, with RoundTick timing, which decouples individual scheduler events from timeout progression. At N=5, increasing the bounded message-delay budget from K=6 to K=14 increased the observed EventCoupled leadership-instability rate from 5\% to 100\% across the tested grid, while no additional valid leader elections occurred in any of the corresponding 140 RoundTick executions. At K=0, neither model produced additional elections. Matched-trace analysis identifies the mechanism: under EventCoupled timing, scheduler activity used to perturb communication also directly advances failure-detector state. Under RoundTick, comparable scheduler activity does not imply equivalent protocol-time progression. A targeted heartbeat-delay control confirms that RoundTick does not suppress timeout-driven elections; an additional election remains reachable when leader contact is unavailable across sufficient logical time.

Problem

• adversarial consensus simulation
• time semantics
• failure detector
• leadership instability
• liveness

Innovation

• Adversarial Consensus Simulation
• Time Semantics
• RoundTick Timing
• Failure Detectors
• Multi-Paxos