JacksonYao287 edited a comment on pull request #500: URL: https://github.com/apache/ratis/pull/500#issuecomment-921432428
@szetszwo thanks for the review! >In requestVote(..), the leader recognizes a candidate only if the candidate has a higher term. Therefore, the leader should change to follower even if it will reject the vote from the candidate. yes , so , we can say that when the leader rejects a vote, it means the candidate must have a term lower or equal than the leader. if a candidate has a higher term, the leader should vote for it and step down to follower. so my point is that , before `changeToFollower` , we should check whether vote is granted. if vote is granted , it means the candidate has a higher term , so it make sense to `changeToFollower` if vote is not granted, it means the candidate has a equal or lower term, `changeToFollower` should not be called. so there does not exist any case that the leader reject the vote and meanwhile `changeToFollower`. pleaser see the attached log below which i have uploaded in this jira. ``` 2021-09-15 18:21:07,529 [grpc-default-executor-617] INFO org.apache.ratis.server.impl.VoteContext: a075f477-2523-4b79-991f-ecbe8ee00d0d@group-8BCFDCD73BCA-LEADER: reject ELECTION from b7bb63db-f11b-49c0-8269-2acf98d5fdd6: our last entry (t:3, i:432782) > candidate's last entry (t:3, i:302053) 2021-09-15 18:21:07,529 [grpc-default-executor-617] INFO org.apache.ratis.server.RaftServer$Division: a075f477-2523-4b79-991f-ecbe8ee00d0d@group-8BCFDCD73BCA: change Leader from a075f477-2523-4b79-991f-ecbe8ee00d0d to null at term 4 for updateCurrentTerm 2021-09-15 18:21:07,529 [grpc-default-executor-617] INFO org.apache.ratis.server.RaftServer$Division: a075f477-2523-4b79-991f-ecbe8ee00d0d@group-8BCFDCD73BCA: changes role from LEADER to FOLLOWER at term 4 for candidate:b7bb63db-f11b-49c0-8269-2acf98d5fdd6 ``` it show that the leader reject the vote because the candidate has a less up-to-date log(same term, but smaller index). after this rejection, the leader does not check whether the candidate has a higher term(voteGranted), and just go ahead to call `changeToFollower`,in which `state.updateCurrentTerm` is called. so , this is what the current patch fixed -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
