> On Nov. 20, 2013, 6:30 p.m., Jun Rao wrote:
> > core/src/main/scala/kafka/controller/KafkaController.scala, lines 745-746
> > <https://reviews.apache.org/r/15711/diff/3/?file=388714#file388714line745>
> >
> >     Could we rename updateZk to sth like isTriggeredByCommandLine?
> 
> Sriram Subramanian wrote:
>     I dont like the external usage to leak into the code. I see your intent 
> to make the usage of this flag more explicit. How about 
> isTriggeredByAutoRebalance and not update zk if it is set?
> 
> Jun Rao wrote:
>     This is fine. My only concern is that updateZK is a bit misleading. We do 
> update the ISR path in ZK. We just don't update the leader balancing path.

Changed it to isTriggeredByAutoRebalance


> On Nov. 20, 2013, 6:30 p.m., Jun Rao wrote:
> > core/src/main/scala/kafka/server/KafkaConfig.scala, lines 236-239
> > <https://reviews.apache.org/r/15711/diff/3/?file=388715#file388715line236>
> >
> >     I am wondering if this config is really necessary. Wouldn't it be 
> > simpler to always do the balancing on all partitions that are not already 
> > on the preferred replica?
> 
> Sriram Subramanian wrote:
>     I do think there is value in this. To ensure rebalance happens always we 
> can set it to 0. There are cases where few topic partition movements does not 
> enforce a rebalance and hence cause unavailability. It is useful to have this 
> to operationalize this feature and understand its behavior in production.
> 
> Jun Rao wrote:
>     I still don't see a strong reason why someone would want to leave some 
> partitions' leader unbalanced. Even one unbalanced leader can cause 
> significant extra load on the broker if the amount of data on that partition 
> is large. The logic in KafkaController is also simplified if we always try to 
> balance all leaders.

Our balancing of topics across topics is very primitive. We do not balance 
based on load or storage. What you suggest will happen even if the number of 
topics are balanced across the brokers. It is valuable to avoid unnecessary 
churn till we understand this feature better in production. I do see a benefit 
in not balancing when only a few topic partitions are imbalanced. Additionally 
the logic to do this is very minimum.


- Sriram


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On Nov. 21, 2013, 5:42 p.m., Sriram Subramanian wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://reviews.apache.org/r/15711/
> -----------------------------------------------------------
> 
> (Updated Nov. 21, 2013, 5:42 p.m.)
> 
> 
> Review request for kafka.
> 
> 
> Bugs: KAFKA-930
>     https://issues.apache.org/jira/browse/KAFKA-930
> 
> 
> Repository: kafka
> 
> 
> Description
> -------
> 
> Merge branch 'trunk' of http://git-wip-us.apache.org/repos/asf/kafka into 
> trunk
> 
> 
> commit missing code
> 
> 
> some more changes
> 
> 
> fix merge conflicts
> 
> 
> Add auto leader rebalance support
> 
> 
> Merge branch 'trunk' of http://git-wip-us.apache.org/repos/asf/kafka into 
> trunk
> 
> 
> Merge branch 'trunk' of http://git-wip-us.apache.org/repos/asf/kafka into 
> trunk
> 
> Conflicts:
>       core/src/main/scala/kafka/admin/AdminUtils.scala
>       core/src/main/scala/kafka/admin/TopicCommand.scala
> 
> change comments
> 
> 
> commit the remaining changes
> 
> 
> Move AddPartitions into TopicCommand
> 
> 
> Diffs
> -----
> 
>   core/src/main/scala/kafka/controller/KafkaController.scala 
> 4c319aba97655e7c4ec97fac2e34de4e28c9f5d3 
>   core/src/main/scala/kafka/server/KafkaConfig.scala 
> b324344d0a383398db8bfe2cbeec2c1378fe13c9 
> 
> Diff: https://reviews.apache.org/r/15711/diff/
> 
> 
> Testing
> -------
> 
> 
> Thanks,
> 
> Sriram Subramanian
> 
>

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