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https://issues.apache.org/jira/browse/ZOOKEEPER-2819?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16065484#comment-16065484
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ASF GitHub Bot commented on ZOOKEEPER-2819:
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Github user hanm commented on the issue:
https://github.com/apache/zookeeper/pull/292
Thanks for review, @shralex @asdf2014 . Code updated.
I also refactored a couple of reconfig tests to consolidate the setting of
the feature flag, which makes the test both easier to read and also fix
potential race conditions I found out while working on this patch: because the
flag was set in a different thread while the peers are running, it is possible
the peer thread still cache old value. Such case would not happen for real use
case (aside from artificial tests we created here) because the feature flag
will not change after ensemble is started.
> Changing membership configuration via rolling restart does not work on 3.5.x.
> -----------------------------------------------------------------------------
>
> Key: ZOOKEEPER-2819
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2819
> Project: ZooKeeper
> Issue Type: Bug
> Components: quorum, server
> Affects Versions: 3.5.0, 3.5.1, 3.5.2, 3.5.3
> Reporter: Michael Han
> Assignee: Michael Han
> Priority: Critical
>
> In 3.5.x there is no easy way of changing the membership config using rolling
> restarts because of the introduction of dynamic reconfig feature in
> ZOOKEEPER-107, which automatically manages membership configuration
> parameters.
> ZOOKEEPER-2014 introduced a reconfigEnabled flag to turn on / off the
> reconfig feature. We can use same flag and when it sets to false, it should
> disable both in memory and on disk updates of membership configuration
> information, besides disabling the reconfig commands on CLI which
> ZOOKEEPER-2014 already did, so users can continue using rolling restarts if
> needed.
> We should also document explicitly the support of membership changes via
> rolling restarts will be deprecated at what release time frame and promote
> reconfig as the replacement.
> The problem was raised at user mailing list by Guillermo Vega-Toro, reference
> thread:
> http://zookeeper-user.578899.n2.nabble.com/How-to-add-nodes-to-a-Zookeeper-3-5-3-beta-ensemble-with-reconfigEnabled-false-td7583138.html
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