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https://issues.apache.org/jira/browse/ZOOKEEPER-1659?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14001610#comment-14001610
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Rakesh R commented on ZOOKEEPER-1659:
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Thanks [~shralex] and [~fpj]
bq.removing a server may not lead to shutting it down - it may be an
intermediate step for changing its role (there are cases where this is
necessary when changing an observer to a follower - an observer can't vote so
if its vote is needed to establish the new config we may need to first remove
it so that its a non-voting follower).
Yeah this is good point, I missed it. Initially I was thinking to identify only
the changed QPs and tried to unregister/re-register it. Now after seeing this
scenario I've diff idea in my mind. How about un-register all the remote beans
and re-register back according to the new QuorumVerifier#getAllMembers() ?.
Here one concern is, all the remote QPs will be unregistered for a moment until
its re-registration, irrespective of QuorumServer has configuration changes or
not. With this approach, code will be simple rather than having complex logic
for diff and identifying only those changed QPs.
ZK JMX hierarchy is:
- jmxQuorumBean (himself registered as parent bean)
** LocalPeerBean (self quorumpeer)
** RemotePeerBean (for each remote qp in the config)
bq. One thing this patch is not handling is quorum system changes. if I
understand correctly if we switch from majority to hierarchical or the other
way around, or change parameters of a hierarchical quorum system, this won't be
reflected in JMX that only has the QuorumServers
Presently Hierarchical system info is not exposed and not available in any of
the existing jmx beans. I also feel, this can be exposed after 3.5.0.
> Add JMX support for dynamic reconfiguration
> -------------------------------------------
>
> Key: ZOOKEEPER-1659
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1659
> Project: ZooKeeper
> Issue Type: Bug
> Components: server
> Affects Versions: 3.5.0
> Reporter: Alexander Shraer
> Assignee: Rakesh R
> Priority: Blocker
> Fix For: 3.5.0
>
> Attachments: ZOOKEEPER-1659.patch
>
>
> We need to update JMX during reconfigurations. Currently, reconfiguration
> changes are not reflected in JConsole.
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