Erik van Oosten created KAFKA-19811:
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Summary: Acked record not immediately visible to consumer
Key: KAFKA-19811
URL: https://issues.apache.org/jira/browse/KAFKA-19811
Project: Kafka
Issue Type: Bug
Affects Versions: 4.1.0
Reporter: Erik van Oosten
h2. Steps to reproduce
* program runs on an in-JVM embedded kafka server
* create a new topic with 1 partition
* produce a record with {{acks=all}}
* await acknowledgement from the broker
* start a consumer (configured to read from beginning of topic)
* spuriously, _the consumer never sees the record_
The problem seems to occur more on a very busy server (e.g. a build server
running many tests in parallel). We have not seen it on a modern laptop.
A delay of 10ms before starting the consumer makes the record always visible.
We observe this problem in ~1 in 5 runs of
[zio-kafka|https://github.com/zio/zio-kafka]'s test suite, when run from a
GitHub action. Since we run the test-suite for 3 different JVM versions, almost
every build fails due to this issue.
h2. Expected behavior
An acknowledged record, produced with {{{}acks=all{}}}, should be immediately
visible for all consumers.
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