Hi Reem,
What's the Flink version where you're encountering this issue?
Best regards,
Martijn
On Wed, Mar 29, 2023 at 5:18 PM Reem Razak via user <user@flink.apache.org>
wrote:
> Hey there!
>
> We are seeing a second Flink pipeline encountering similar issues when
> configuring both `withWatermarkAlignment` and `withIdleness`. The
> unexpected behaviour gets triggered after a Kafka cluster failover. Any
> thoughts on there being an incompatibility between the two?
>
> Thanks!
>
> On Wed, Nov 9, 2022 at 6:42 PM Reem Razak <reem.ra...@shopify.com> wrote:
>
>> Hi there,
>>
>> We are integrating the watermark alignment feature into a pipeline with a
>> Kafka source during a "backfill"- i.e. playing from an earlier Kafka
>> offset. While testing, we noticed some unexpected behaviour in the
>> watermark advancement which was resolved by removing `withIdleness` from
>> our watermark strategy.
>>
>>
>> val watermarkStrategy = WatermarkStrategy
>> .forBoundedOutOfOrderness(Duration.ofMinutes(1))
>> .withTimestampAssigner(new TimestampedEventTimestampAssigner[Event])
>> .withWatermarkAlignment("alignment-group-1", Duration.ofMinutes(1))
>> .withIdleness(Duration.ofMinutes(5))
>>
>> I have attached a couple of screenshots of the watermarkAlignmentDrift
>> metric. As you can see, the behaviour seems normal until a sudden drop in
>> the value to ~ Long.MIN_VALUE, which causes the pipeline to stop emitting
>> records completely from the source. Furthermore, the logs originating from
>> from
>> https://github.com/dawidwys/flink/blob/888162083fbb5f62f809e5270ad968db58cc9c5b/flink-runtime/src/main/java/org/apache/flink/runtime/source/coordinator/SourceCoordinator.java#L174
>> also indicate that the `maxAllowedWatermark` switches to ~ Long.MIN_VALUE.
>>
>> We found that modifying the `updateInterval` passed into the alignment
>> parameters seemed to correlate with how long the pipeline would operate
>> before stopping - a larger interval of 20 minutes would encounter the issue
>> later than an interval of 1 second.
>>
>> We are wondering if a bug exists when using both `withIdleness` and
>> `withWatermarkAlignment`. Might it be related to
>> https://issues.apache.org/jira/browse/FLINK-28975, or is there possibly
>> a race condition in the watermark emission? We do not necessarily need to
>> have both configured at the same time, but we were also surprised by the
>> behaviour of the application. Has anyone run into a similar issue or have
>> further insight?
>>
>> Much Appreciated,
>> - Reem
>>
>>
>>
>>
