Damien Gasparina created KAFKA-14302:
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Summary: Infinite probing rebalance if a changelog topic got
emptied
Key: KAFKA-14302
URL: https://issues.apache.org/jira/browse/KAFKA-14302
Project: Kafka
Issue Type: Bug
Components: streams
Affects Versions: 3.3.1
Reporter: Damien Gasparina
Attachments: image-2022-10-14-12-04-01-190.png
If a store, with a changelog topic, has been fully emptied, it could generate
infinite probing rebalance.
The scenario is the following:
* A Kafka Streams application have a store with a changelog
* Many entries are pushed into the changelog, thus the Log end Offset is high,
let's say 20,000
* Then, the store got emptied, either due to data retention (windowing) or
tombstone
* Then an instance of the application is restarted
* It restores the store from the changelog, but does not write a checkpoint
file as there are no data pushed at all
* As there are no checkpoint entries, this instance specify a taskOffsetSums
with offset set to 0 in the subscriptionUserData
* The group leader, during the assignment, then compute a lag of 20,000 (end
offsets - task offset), which is greater than the default acceptable lag, thus
decide to schedule a probing rebalance
* In ther next probing rebalance, nothing changed, so... new probing rebalance
I was able to reproduce locally with a simple topology:
{code:java}
var table = streamsBuilder.stream("table");
streamsBuilder
.stream("stream")
.join(table, (eSt, eTb) -> eSt.toString() + eTb.toString(),
JoinWindows.of(Duration.ofSeconds(5)))
.to("output");{code}
Due to this issue, application having an empty changelog are experiencing
frequent rebalance:
!image-2022-10-14-12-04-01-190.png!
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