[jira] [Commented] (FLINK-4027) FlinkKafkaProducer09 sink can lose messages

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-4027?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15361109#comment-15361109 ] 

ASF GitHub Bot commented on FLINK-4027:
---------------------------------------

Github user asfgit closed the pull request at:

    https://github.com/apache/flink/pull/2108


> FlinkKafkaProducer09 sink can lose messages
> -------------------------------------------
>
>                 Key: FLINK-4027
>                 URL: https://issues.apache.org/jira/browse/FLINK-4027
>             Project: Flink
>          Issue Type: Bug
>          Components: Kafka Connector
>    Affects Versions: 1.0.3
>            Reporter: Elias Levy
>            Assignee: Robert Metzger
>            Priority: Critical
>             Fix For: 1.1.0
>
>
> The FlinkKafkaProducer09 sink appears to not offer at-least-once guarantees.
> The producer is publishing messages asynchronously.  A callback can record publishing errors, which will be raised when detected.  But as far as I can tell, there is no barrier to wait for async errors from the sink when checkpointing or to track the event time of acked messages to inform the checkpointing process.
> If a checkpoint occurs while there are pending publish requests, and the requests return a failure after the checkpoint occurred, those message will be lost as the checkpoint will consider them processed by the sink.



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