[IGNITE-15632] Investigate jraft's BallotBox optimisation in case of removing peer

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Labels: ignite-3
• Ignite Flags: Docs Required, Release Notes Required
• Assignee: Unassigned
• Reporter: Mirza Aliev
• Created: 28/Sep/21 11:38
• Updated: 26/Jan/22 14:50

Description

org.apache.ignite.raft.jraft.core.BallotBox#commitAt method contains comment from jraft developers about optimization which commits uncommitted logs in case of decreasing of quorum. This optimization is not proven, needs to be investigated.

Comment:

            // When removing a peer off the raft group which contains even number of
            // peers, the quorum would decrease by 1, e.g. 3 of 4 changes to 2 of 3. In
            // this case, the log after removal may be committed before some previous
            // logs, since we use the new configuration to deal the quorum of the
            // removal request, we think it's safe to commit all the uncommitted
            // previous logs, which is not well proved right now

Ticket was created after the decomposition of https://issues.apache.org/jira/browse/IGNITE-14832
See todo in org.apache.ignite.raft.jraft.core.BallotBox#commitAt

Issue Links

• is a child of: IGNITE-14832 Investigate remaining TODOs in org.apache.ignite.raft.jraft package