[
https://issues.apache.org/jira/browse/FLINK-4069?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15328840#comment-15328840
]
Tzu-Li (Gordon) Tai commented on FLINK-4069:
--------------------------------------------
Thanks for creating this JIRA Shannon. However, there's already a previously
opened JIRA on this problem: https://issues.apache.org/jira/browse/FLINK-4023.
Let's track this issue on FLINK-4023 on close this as a duplicate issue :) I've
referenced a link to this JIRA on FLINK-4023.
> Kafka Consumer should not initialize on construction
> ----------------------------------------------------
>
> Key: FLINK-4069
> URL: https://issues.apache.org/jira/browse/FLINK-4069
> Project: Flink
> Issue Type: Improvement
> Components: Kafka Connector
> Affects Versions: 1.0.3
> Reporter: Shannon Carey
>
> The Kafka Consumer connector currently interacts over the network with Kafka
> in order to get partition metadata when the class is constructed. Instead, it
> should do that work when the job actually begins to run (for example, in
> AbstractRichFunction#open() of FlinkKafkaConsumer0?).
> The main weakness of broker querying in the constructor is that if there are
> network problems, Flink might take a long time (eg. ~1hr) inside the
> user-supplied main() method while it attempts to contact each broker and
> perform retries. In general, setting up the Kafka partitions does not seem
> strictly necessary as part of execution of main() in order to set up the job
> plan/topology.
> However, as Robert Metzger mentions, there are important concerns with how
> Kafka partitions are handled:
> "The main reason why we do the querying centrally is:
> a) avoid overloading the brokers
> b) send the same list of partitions (in the same order) to all parallel
> consumers to do a fixed partition assignments (also across restarts). When we
> do the querying in the open() method, we need to make sure that all
> partitions are assigned, without duplicates (also after restarts in case of
> failures)."
> See also the mailing list discussion:
> http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/API-request-to-submit-job-takes-over-1hr-td7319.html
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
