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From "Benjamin Reed (JIRA)" <j...@apache.org>
Subject [jira] Updated: (ZOOKEEPER-157) Peer can't find existing leader
Date Sat, 04 Oct 2008 23:25:44 GMT

     [ https://issues.apache.org/jira/browse/ZOOKEEPER-157?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Benjamin Reed updated ZOOKEEPER-157:

    Hadoop Flags: [Reviewed]

+1 looks good.

> Peer can't find existing leader
> -------------------------------
>                 Key: ZOOKEEPER-157
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-157
>             Project: Zookeeper
>          Issue Type: Bug
>    Affects Versions: 3.0.0
>            Reporter: Flavio Paiva Junqueira
>            Assignee: Flavio Paiva Junqueira
>            Priority: Critical
>         Attachments: ZOOKEEPER-157.patch
> In the patch of JIRA 127, I forgot to set the state of a peer when this peer is looking
for a leader and it receives a message from the current leader. In this patch, I have fixed
this problem, and also returned to what we had previously. With this current patch, when a
peer joins and there is already a leader elected, the joining peer will only recognize the
new leader as the leader once it receives a confirmation from a majority. The alternative
is to set the leader once we receive a message from a peer claiming to be the leader (what
we have on trunk now, although broken because we don't set the state of the peer), but there
could be cases in which a peer believes to be leader, although it is not the leader any longer,
and the joining peer would select this false leader to be its leader. Eventually, the false
leader would timeout, and both processes would select the correct leader. This small fix gets
rid of such problems, though.

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