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https://issues.apache.org/jira/browse/HBASE-16835?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15578021#comment-15578021
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Duo Zhang commented on HBASE-16835:
-----------------------------------
As I said in HBASE-15921, I always use watcher together with zookeeper. And why
I say it makes the code simpler is that, usually we will cache the data in
memory if we use watcher, so we can just expose a synchronous interface for
getting the data to the upper layer since an in memory get is very fast and
will not block anything. And the upper layer does not need to care about the
update of the value, it will be updated by watcher automatically. Of course the
value maybe stale but I think it is acceptable as we have retrying in the upper
layer.
And yes watcher will slow down the cluster, especially that it will cause a
network storm if we update a node that watched by every client. So I think at
least we should not use watcher for everything we want at client side, for
example, the current alive RS count.
> Revisit the zookeeper usage at client side
> ------------------------------------------
>
> Key: HBASE-16835
> URL: https://issues.apache.org/jira/browse/HBASE-16835
> Project: HBase
> Issue Type: Sub-task
> Reporter: Duo Zhang
>
> Watcher or not.
> Curator or not.
> Keep connection or not.
> ...
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