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https://issues.apache.org/jira/browse/ZOOKEEPER-1465?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13281679#comment-13281679
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Marshall McMullen commented on ZOOKEEPER-1465:
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How confident are we in the fix for this bug? I'm patching our local zookeeper
and we've definitely observed this bug ourselves. Would like to incorporate it
into our next patched version but would love some feedback on this fix...Thanks!
> Cluster availability following new leader election takes a long time with
> large datasets - is correlated to dataset size
> ------------------------------------------------------------------------------------------------------------------------
>
> Key: ZOOKEEPER-1465
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1465
> Project: ZooKeeper
> Issue Type: Bug
> Components: leaderElection
> Affects Versions: 3.4.3
> Reporter: Alex Gvozdenovic
> Assignee: Camille Fournier
> Priority: Critical
> Fix For: 3.4.4
>
> Attachments: ZOOKEEPER-1465.patch
>
>
> When re-electing a new leader of a cluster, it takes a long time for the
> cluster to become available if the dataset is large
> Test Data
> ----------
> 650mb snapshot size
> 20k nodes of varied size
> 3 member cluster
> On 3.4.x branch
> (http://svn.apache.org/repos/asf/zookeeper/branches/branch-3.4?r=1244779)
> ------------------------------------------------------------------------------------------
> Takes 3-4 minutes to bring up a cluster from cold
> Takes 40-50 secs to recover from a leader failure
> Takes 10 secs for a new follower to join the cluster
> Using the 3.3.5 release on the same hardware with the same dataset
> -----------------------------------------------------------------
> Takes 10-20 secs to bring up a cluster from cold
> Takes 10 secs to recover from a leader failure
> Takes 10 secs for a new follower to join the cluster
> I can see from the logs in 3.4.x that once a new leader is elected, it pushes
> a new snapshot to each of the followers who need to save it before they ack
> the leader who can then mark the cluster as available.
> The kit being used is a low spec vm so the times taken are not relevant per
> se - more the fact that a snapshot is always sent even through there is no
> difference between the persisted state on each peer.
> No data is being added to the cluster while the peers are being restarted.
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