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https://issues.apache.org/jira/browse/SAMZA-1336?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Boris Shkolnik updated SAMZA-1336:
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Description:
If ZK doesn't receive any communication from a zkClient (including heartbeats)
for a session timeout period, it closes the session with the client. It removes
all the ephemeral nodes associated with the client. That's why we need to
restore all these nodes - need to re-register.
We are using ZkClient library to connect to zookeeper. This library allows us
to get notification when the session is closed and when a new session is
created. So when the new session is created we reset all session related state
and re-register.
One weird feature of the library/zookeeper is that when a new session is
established, it is still possible to receive old notifications. To avoid this
we introduce generation number which we pass into each callback. And if the
generation number has changed when the callback was invoked, we will ignore
this callback.
was:When Zk session expires, it looses connection to the server. The server
will expire all the ephemeral nodes for this client. As the result we need to
re-register with the ZK.
> session expiration propagation
> -------------------------------
>
> Key: SAMZA-1336
> URL: https://issues.apache.org/jira/browse/SAMZA-1336
> Project: Samza
> Issue Type: Sub-task
> Reporter: Boris Shkolnik
> Assignee: Boris Shkolnik
> Fix For: 0.13.0
>
>
> If ZK doesn't receive any communication from a zkClient (including
> heartbeats) for a session timeout period, it closes the session with the
> client. It removes all the ephemeral nodes associated with the client. That's
> why we need to restore all these nodes - need to re-register.
> We are using ZkClient library to connect to zookeeper. This library allows us
> to get notification when the session is closed and when a new session is
> created. So when the new session is created we reset all session related
> state and re-register.
> One weird feature of the library/zookeeper is that when a new session is
> established, it is still possible to receive old notifications. To avoid this
> we introduce generation number which we pass into each callback. And if the
> generation number has changed when the callback was invoked, we will ignore
> this callback.
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