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https://issues.apache.org/jira/browse/FLINK-29827?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Danny Cranmer reassigned FLINK-29827:
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Assignee: Ahmed Hamdy
> [Connector][AsyncSinkWriter] Checkpointed states block writer from sending
> records
> ----------------------------------------------------------------------------------
>
> Key: FLINK-29827
> URL: https://issues.apache.org/jira/browse/FLINK-29827
> Project: Flink
> Issue Type: Bug
> Components: Connectors / Common
> Affects Versions: 1.15.2
> Reporter: Hoang Tri Tam
> Assignee: Ahmed Hamdy
> Priority: Major
>
> Hi every one,
> Recently we discovered an issue which blocks Sink operators from sending
> records to client's endpoint.
> To *reproduce* the issue, we started our Flink app from an existing
> savepoint, in which some Sink operators hold some buffered records. For
> instance, app employs KinesisStreamSink with a parallelism of 4. 2 of them
> has no buffered records, the other 2 start with existing states of some
> records, which are leftover from the previous run.
> {*}Behavior{*}: during runtime, we sent records (let's say 200) to this sink
> in rebalance mode. But only 100 of them (50%) were dispatched from the sink
> operators.
> After {*}investigation{*}, we found that the implementation AsyncSinkWriter
> invokes submitRequestEntries() to send the records to their destination. This
> invocation is performed when a callback is performed, a flush(true) or
> forced-flush is called, or when the buffered is full (either in size or in
> quantity).
> The case falls in the first scenario: the _callback is not registered_
> {_}when the writer starts with some existing buffered records{_}, initialized
> from savepoint. Hence in our case, those operators were holding records till
> their buffers become full, while other operators still perform the usual
> sending.
> Impacted {*}scope{*}: flink-1.15.2 or later version, for any Sink that
> implements AsyncSinkWriter.
> We currently treat this as an abnormal behavior of Flink, but please let me
> know if this behavior is intended by design.
> Thanks in advance.
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