v.25.12Improvement
Add a keeper-server-side check during handshake
Add a keeper-server-side check during handshake to reject clients when last_zxid_seen (provided by the client) > last_processed_zxid. This prevents stale reads when clients reconnect to lagging replicas. #90016 (Miсhael Stetsyuk).Why it matters
This feature prevents stale reads by ensuring that clients connecting to lagging replicas with outdated state information are rejected during the handshake, improving consistency and correctness in replicated environments.How to use it
The check is performed automatically during the keeper handshake. Clients will be rejected if theirlast_zxid_seen is higher than the server's last_processed_zxid. No additional configuration is required from the user.