[GitHub] zookeeper pull request #438: ZOOKEEPER-2959: ignore accepted epoch and LEADE...

[shralex <gi...@git.apache.org>]

Github user shralex commented on a diff in the pull request:

    https://github.com/apache/zookeeper/pull/438#discussion_r179363930
  
    --- Diff: src/java/main/org/apache/zookeeper/server/quorum/Leader.java ---
    @@ -1183,8 +1183,10 @@ public long getEpochToPropose(long sid, long lastAcceptedEpoch) throws Interrupt
                 if (lastAcceptedEpoch >= epoch) {
                     epoch = lastAcceptedEpoch+1;
                 }
    -            connectingFollowers.add(sid);
                 QuorumVerifier verifier = self.getQuorumVerifier();
    +            if(verifier.getVotingMembers().containsKey(sid)) {
    --- End diff --
    
    If I recall correctly, the reason this wasn't done are concerns around the impact on performance - containsQuorum is called every time an ACK is received for every operation proposal. So if you need 3 asks to commit an operation, we'll be doing these checks (figuring out who's a participant and who's not} for {ACK1}, for {ACK1, ACK2} and for {ACK1, ACK2, ACK3}. This compared to comparing two ints as it stands now. So this is why it wasn't done...


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