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https://issues.apache.org/jira/browse/FLINK-40501?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated FLINK-40501:
-----------------------------------
Labels: pull-request-available (was: )
> WatermarkStatus overtakes queued watermarks in AsyncWaitOperator, causing
> watermark loss downstream
> ---------------------------------------------------------------------------------------------------
>
> Key: FLINK-40501
> URL: https://issues.apache.org/jira/browse/FLINK-40501
> Project: Flink
> Issue Type: Bug
> Components: API / DataStream, Runtime / Task
> Reporter: Martijn Visser
> Priority: Major
> Labels: pull-request-available
>
> {{AsyncWaitOperator.processWatermark}} enqueues watermarks into the ordered
> async work
> queue ({{AsyncWaitOperator.java:286-293}}), but the operator has no
> {{processWatermarkStatus}} override, so
> {{AbstractStreamOperator.processWatermarkStatus}}
> forwards IDLE/ACTIVE immediately. A status element that arrives *after* a
> watermark can
> therefore be emitted *before* it.
> Demonstration (ORDERED mode, async completion withheld) — red on master:
> arrival order {{[record, W100, IDLE]}} produces emission order
> {{[WatermarkStatus(IDLE), record, W100]}}.
> The reordering is not benign: feeding the emitted sequence {{[IDLE, W100]}}
> into a
> downstream {{StatusWatermarkValve}} drops W100 entirely — watermarks arriving
> on an idle
> channel are ignored. The watermark is lost, not delayed; downstream stalls
> until a later
> watermark arrives on that edge, permanently if it was the final one (e.g.
> MAX_WATERMARK
> at drain).
> {{RowTimeMiniBatchAssignerOperator}} has the same shape by inspection: it
> buffers
> watermarks until the mini-batch boundary but forwards status immediately (no
> {{processWatermarkStatus}} override).
> Proposed fix: route {{WatermarkStatus}} through the async queue with the same
> ordering
> guarantees as watermarks (the recovery replay in {{open()}} currently throws
> on
> non-record/watermark/latency elements and would need extension), or hold back
> the status
> until previously queued watermarks have been flushed.
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