Tzu-Li (Gordon) Tai created FLINK-5479:
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Summary: Per-partition watermarks in FlinkKafkaConsumer should
consider idle partitions
Key: FLINK-5479
URL: https://issues.apache.org/jira/browse/FLINK-5479
Project: Flink
Issue Type: Improvement
Components: Kafka Connector
Reporter: Tzu-Li (Gordon) Tai
Fix For: 1.3.0
Reported in ML:
http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/Kafka-topic-partition-skewness-causes-watermark-not-being-emitted-td11008.html
Similar to what's happening to idle sources blocking watermark progression in
downstream operators (see FLINK-5017), the per-partition watermark mechanism in
`FlinkKafkaConsumer` is also being blocked of progressing watermarks when a
partition is idle. The watermark of idle partitions is always `Long.MIN_VALUE`,
therefore the overall min watermark across all partitions of a consumer subtask
will never proceed.
It's normally not a common case to have Kafka partitions not producing any
data, but it'll probably be good to handle this as well. I think we should have
a localized solution similar to FLINK-5017 for the per-partition watermarks in
`AbstractFetcher`.
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