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https://issues.apache.org/jira/browse/ZOOKEEPER-3099?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16649635#comment-16649635
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Jiafu Jiang commented on ZOOKEEPER-3099:
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[~lvfangmin] thanks for your advice. I have changed the title and the
description.
> ZooKeeper cluster is unavailable for session_timeout time due to network
> partition in a three-node environment.
> ------------------------------------------------------------------------------------------------------------------
>
> Key: ZOOKEEPER-3099
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-3099
> Project: ZooKeeper
> Issue Type: Bug
> Components: c client, java client
> Affects Versions: 3.4.11, 3.5.4, 3.4.12, 3.4.13
> Reporter: Jiafu Jiang
> Priority: Major
>
>
> The default readTimeout timeout of ZooKeeper client is 2/3 * session_time,
> the default connectTimeout is session_time/hostProvider.size(). If the
> ZooKeeper cluster has 3 nodes, then connectTimeout is 1/3 * session_time.
>
> Supports we have three ZooKeeper servers: zk1, zk2, zk3 deployed. And zk3 is
> now the leader. Client c1 is now connected to zk2(follower). Then we shutdown
> the network of zk3(leader), the same time, client c1 begin to write some data
> to ZooKeeper. After a (syncLimit * tick) timeout, zk2 will disconnect with
> leader and begin a new election, and zk2 becomes the leader.
>
> The write operation will not succeed due to the leader is unavailable. It
> will take at most readTimeout time for c1 to discover the failure, and client
> c1 will try to choose another ZooKeeper server. Unfortunately, c1 may choose
> zk3, which is unreachable now, then c1 will spend connectTimeout to find out
> that zk3 is unused. Notice that readTimeout + connectTimeout =
> sesstion_timeout in my case(three-node cluster).
>
> Therefore, in this case, the ZooKeeper cluster is unavailable for session
> timeout time when only one ZooKeeper server is unreachable due to network
> partition.
>
> I have some suggestions:
> # The HostProvider used by ZooKeeper can be specified by an argument.
> # readTimeout can also be specified in any way.
>
>
>
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