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https://issues.apache.org/jira/browse/KAFKA-3818?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15332524#comment-15332524
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Grant Henke commented on KAFKA-3818:
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A few older threads mention that its possible to get clumping (due to the hash
on the RoundRobinAssignor). Does that problem still exist? Is that something we
should fix before changing the default?
This thread discusses it recently:
http://search-hadoop.com/m/uyzND135BcA1lXiM&subj=Re+DISCUSS+KIP+49+Fair+Partition+Assignment+Strategy
{quote}
- WRT roundrobin we later realized a significant flaw in the way we lay
out partitions: we originally wanted to randomize the partition layout to
reduce the likelihood of most partitions of the same topic from ending up
on a given consumer which is important if you have a few very large topics.
Unfortunately we used hashCode - which does a splendid job of clumping
partitions from the same topic together :( We can probably just "fix" that
in the new consumer's roundrobin assignor.
{quote}
And this older jira looks to describe the issue [~jjkoshy] is referring to:
KAFKA-2019
[~jjkoshy] do you have any thoughts?
> Change Mirror Maker default assignment strategy to round robin
> --------------------------------------------------------------
>
> Key: KAFKA-3818
> URL: https://issues.apache.org/jira/browse/KAFKA-3818
> Project: Kafka
> Issue Type: Bug
> Reporter: Jason Gustafson
> Assignee: Vahid Hashemian
>
> It might make more sense to use round robin assignment by default for MM
> since it gives a better balance between the instances, in particular when the
> number of MM instances exceeds the typical number of partitions per topic.
> There doesn't seem to be any need to keep range assignment since
> copartitioning is not an issue.
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