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From Germán Blanco (JIRA) <j...@apache.org>
Subject [jira] [Commented] (ZOOKEEPER-1805) "Don't care" value in ZooKeeper election breaks rolling upgrades
Date Mon, 04 Nov 2013 00:38:17 GMT

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-1805?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13812538#comment-13812538
] 

Germán Blanco commented on ZOOKEEPER-1805:
------------------------------------------

Don't care values don't go over the network because they are never sent. The only vote that
gets sent over the network in the block where don't care values are used, is the one returned
by the function lookForLeader, and that one doesn't have any don't care value:
{noformat}
                            Vote endVote = new Vote(n.leader, n.zxid, n.peerEpoch);
                            leaveInstance(endVote);
                            return endVote;
{noformat}
All votes in the outofelection collection of a server with the ZOOKEEPER-1732 patch applied
have don't care values. None of the votes in the outofelection collection of servers without
the ZOOKEEPER-1732 patch applied have don't care values. I was talking about the first case,
in any case, there is never a mixture of the two *in a single zookeeper server* which is where
they get compared. As you can see in the line where votes are inserted in the outofelection
collection (patch applied), all votes inserted there have the don't care value (first sentence
below):
{noformat}
                        outofelection.put(n.sid, new Vote(n.leader, 
                                IGNOREVALUE, IGNOREVALUE, n.peerEpoch, n.state));
                        if (termPredicate(outofelection, new Vote(n.leader,
                                IGNOREVALUE, IGNOREVALUE, n.peerEpoch, n.state))
                                && checkLeader(outofelection, n.leader, IGNOREVALUE))
{
{noformat}

> "Don't care" value in ZooKeeper election breaks rolling upgrades
> ----------------------------------------------------------------
>
>                 Key: ZOOKEEPER-1805
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1805
>             Project: ZooKeeper
>          Issue Type: Bug
>            Reporter: Flavio Junqueira
>            Assignee: Flavio Junqueira
>            Priority: Blocker
>             Fix For: 3.4.6, 3.5.0
>
>         Attachments: ZOOKEEPER-1805-b3.4.patch, ZOOKEEPER-1805.patch, ZOOKEEPER-1805.patch,
ZOOKEEPER-1805.patch, ZOOKEEPER-1805.patch, ZOOKEEPER-1805.patch, ZOOKEEPER-1805.patch, ZOOKEEPER-1805.patch,
ZOOKEEPER-1805.patch
>
>
> This is an issue that has been originally reported in ZOOKEEPER-1732.



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