[
https://issues.apache.org/jira/browse/KAFKA-4214?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15524218#comment-15524218
]
ASF GitHub Bot commented on KAFKA-4214:
---------------------------------------
GitHub user apurvam opened a pull request:
https://github.com/apache/kafka/pull/1910
KAFKA-4214:kafka-reassign-partitions fails all the time when brokers are
bounced during reassignment
There is a corner case bug, where during partition reassignment, if the
controller and a broker receiving a new replica are bounced at the same
time, the partition reassignment is failed.
The cause of this bug is a block of code in the KafkaController which
fails the reassignment if the aliveNewReplicas != newReplicas, ie. if
some of the new replicas are offline at the time a controller fails
over.
The fix is to have the controller listen for ISR change events even for
new replicas which are not alive when the controller boots up. Once the
said replicas come online, they will be in the ISR set, and the new
controller will detect this, and then mark the reassignment as
successful.
Interestingly, the block of code in question was introduced in
KAFKA-990, where a concern about this exact scenario was raised :)
This bug was revealed in the system tests in
https://github.com/apache/kafka/pull/1904.
The relevant tests will be enabled in either this or a followup PR when
PR-1904 is merged.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/apurvam/kafka KAFKA-4214
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/kafka/pull/1910.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #1910
----
commit 7f9814466592f549e8fcde914815c35dcb5a046d
Author: Apurva Mehta <apurva.1...@gmail.com>
Date: 2016-09-26T21:11:44Z
There is a corner case bug, where during partition reassignment, if the
controller and a broker receiving a new replica are bounced at the same
time, the partition reassignment is failed.
The cause of this bug is a block of code in the KafkaController which
fails the reassignment if the aliveNewReplicas != newReplicas, ie. if
some of the new replicas are offline at the time a controller fails
over.
The fix is to have the controller listen for ISR change events even for
new replicas which are not alive when the controller boots up. Once the
said replicas come online, they will be in the ISR set, and the new
controller will detect this, and then mark the reassignment as
successful.
Interestingly, the block of code in question was introduced in
KAFKA-990, where a concern about this exact scenario was raised :)
----
> kafka-reassign-partitions fails all the time when brokers are bounced during
> reassignment
> -----------------------------------------------------------------------------------------
>
> Key: KAFKA-4214
> URL: https://issues.apache.org/jira/browse/KAFKA-4214
> Project: Kafka
> Issue Type: Bug
> Reporter: Apurva Mehta
> Assignee: Apurva Mehta
>
> Due to KAFKA-4204, we never realized that the existing system test for
> testing reassignment would always fail when brokers were bounced in mid
> process. This happens reliably, even for topics of varying number of
> partition and varying replication factors.
> In particular, we see errors like this in the logs when the brokers are
> bounced:
> {noformat}
> Status of partition reassignment:
> ERROR: Assigned replicas (1,2) don't match the list of replicas for
> reassignment (1) for partition [test_topic,2]
> Reassignment of partition [test_topic,1] completed successfully
> Reassignment of partition [test_topic,2] failed
> Reassignment of partition [test_topic,3] completed successfully
> Reassignment of partition [test_topic,0] is still in progress
> {noformat}
> Currently, the tests which bounce brokers during reassignment are disabled
> until this bug is fixed.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
