[
https://issues.apache.org/jira/browse/KAFKA-10606?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17214130#comment-17214130
]
Lincong Li commented on KAFKA-10606:
------------------------------------
Hi [~tombentley] [~ijuma] I just created a PR. Let me know if you have any
feedback or suggestions. Thanks!
https://github.com/apache/kafka/pull/9435
> Auto create non-existent topics when fetching metadata for all topics
> ---------------------------------------------------------------------
>
> Key: KAFKA-10606
> URL: https://issues.apache.org/jira/browse/KAFKA-10606
> Project: Kafka
> Issue Type: Bug
> Reporter: Lincong Li
> Assignee: Lincong Li
> Priority: Major
>
> The "allow auto topic creation" flag is hardcoded to be true for the
> fetch-all-topic metadata request:
> https://github.com/apache/kafka/blob/trunk/clients/src/main/java/org/apache/kafka/common/requests/MetadataRequest.java#L37
> In the below code, annotation claims that "*This never causes
> auto-creation*". It it NOT true and auto topic creation still gets triggered
> under some circumstances. So, this is a bug that needs to be fixed.
> https://github.com/apache/kafka/blob/trunk/clients/src/main/java/org/apache/kafka/common/requests/MetadataRequest.java#L68
> For example, the bug could be manifested in the below situation:
> A topic T is being deleted and a request to fetch metadata for all topics
> gets sent to one broker. The broker reads names of all topics from its
> metadata cache (shown below).
> https://github.com/apache/kafka/blob/trunk/core/src/main/scala/kafka/server/KafkaApis.scala#L1196
> Then the broker authorizes all topics and makes sure that they are allowed to
> be described. Then the broker tries to get metadata for every authorized
> topic by reading the metadata cache again, once for every topic (show below).
> https://github.com/apache/kafka/blob/trunk/core/src/main/scala/kafka/server/KafkaApis.scala#L1240
> However, the metadata cache could have been updated while the broker was
> authorizing all topics and topic T and its metadata no longer exist in the
> cache since the topic got deleted and metadata update requests eventually got
> propagated from the controller to all brokers. So, at this point, when the
> broker tries to get metadata for topic T from its cache, it realizes that it
> does not exist and the broker tries to "auto create" topic T since the
> allow-auto-topic-creation flag was set to true in all the fetch-all-topic
> metadata requests.
> I think this bug exists since "*metadataRequest.allowAutoTopicCreation*" was
> introduced.
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
