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https://issues.apache.org/jira/browse/ZOOKEEPER-2016?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14114855#comment-14114855
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Alexander Shraer commented on ZOOKEEPER-2016:
---------------------------------------------
Hi Hongchao,
this looks very nice!
to avoid the first connect issue you could do something like this:
if (version == -1) {
version = configVersion;
return;
}
of course there still should be some default policy, like sleeping between min
and max.
alternatively, perhaps its more flexible if before calling updateServerList the
code calls a function provided in the policy class by the user.
The way I tested these things is using a modified system test, where each
server also reports the number of client connections and not only performance
stats. Then while the system test is running you could invoke a reconfig and
see what happens to the number of client connections per server.
We have StaticHostProvider tests for rebalancing, but they don't create a
ZooKeeper object, IIRC.
Perhaps you could do it in a unit test. For example if you have 5 servers,
start 100 clients with a connection string including all of them. Then
reconfigure to remove one server, and make sure that the number of clients
connected to the removed server goes to 0 and each remaining server is
approximately the same.
> Automate client-side rebalancing
> --------------------------------
>
> Key: ZOOKEEPER-2016
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2016
> Project: ZooKeeper
> Issue Type: Improvement
> Reporter: Hongchao Deng
> Attachments: draft-2.patch, draft.patch
>
>
> ZOOKEEPER-1355 introduced client-side rebalancing, which is implemented in
> both the C and Java client libraries. However, it requires the client to
> detect a configuration change and call updateServerList with the new
> connection string (see reconfig manual). It may be better if the client just
> indicates that he is interested in this feature when creating a ZK handle and
> we'll detect configuration changes and invoke updateServerList for him
> underneath the hood.
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