[
https://issues.apache.org/jira/browse/KAFKA-1792?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14233620#comment-14233620
]
Neha Narkhede commented on KAFKA-1792:
--------------------------------------
[~Dmitry Pekar] Thanks for the updated patch. Left review comments.
Also, on the testing side, since this is useful only once while accepting this
algorithm, these don't have to be repeatable. Also the nature of these tests is
that of reporting not correctness, so I wasn't thinking of these as unit tests.
Would you like to share the test results? I think the tests should exercise the
common scenarios of adding new brokers, decommissioning brokers and some of
just reassignments for reaching a balanced load distribution.
> change behavior of --generate to produce assignment config with fair replica
> distribution and minimal number of reassignments
> -----------------------------------------------------------------------------------------------------------------------------
>
> Key: KAFKA-1792
> URL: https://issues.apache.org/jira/browse/KAFKA-1792
> Project: Kafka
> Issue Type: Sub-task
> Components: tools
> Reporter: Dmitry Pekar
> Assignee: Dmitry Pekar
> Fix For: 0.8.3
>
> Attachments: KAFKA-1792.patch, KAFKA-1792_2014-12-03_19:24:56.patch
>
>
> Current implementation produces fair replica distribution between specified
> list of brokers. Unfortunately, it doesn't take
> into account current replica assignment.
> So if we have, for instance, 3 brokers id=[0..2] and are going to add fourth
> broker id=3,
> generate will create an assignment config which will redistribute replicas
> fairly across brokers [0..3]
> in the same way as those partitions were created from scratch. It will not
> take into consideration current replica
> assignment and accordingly will not try to minimize number of replica moves
> between brokers.
> As proposed by [~charmalloc] this should be improved. New output of improved
> --generate algorithm should suite following requirements:
> - fairness of replica distribution - every broker will have R or R+1 replicas
> assigned;
> - minimum of reassignments - number of replica moves between brokers will be
> minimal;
> Example.
> Consider following replica distribution per brokers [0..3] (we just added
> brokers 2 and 3):
> - broker - 0, 1, 2, 3
> - replicas - 7, 6, 0, 0
> The new algorithm will produce following assignment:
> - broker - 0, 1, 2, 3
> - replicas - 4, 3, 3, 3
> - moves - -3, -3, +3, +3
> It will be fair and number of moves will be 6, which is minimal for specified
> initial distribution.
> The scope of this issue is:
> - design an algorithm matching the above requirements;
> - implement this algorithm and unit tests;
> - test it manually using different initial assignments;
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
