Bruno Cadonna created KAFKA-9572:
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Summary: Sum Computation with Exactly-Once Enabled and Injected
Failures Misses Some Records
Key: KAFKA-9572
URL: https://issues.apache.org/jira/browse/KAFKA-9572
Project: Kafka
Issue Type: Bug
Components: streams
Affects Versions: 2.4.0
Reporter: Bruno Cadonna
Attachments: 7-changelog-1.txt, data-1.txt, streams22.log,
streams23.log, streams30.log, sum-1.txt
System test {{StreamsEosTest.test_failure_and_recovery}} failed due to a
wrongly computed aggregation under exactly-once (EOS). The specific error is:
{code:java}
Exception in thread "main" java.lang.RuntimeException: Result verification
failed for ConsumerRecord(topic = sum, partition = 1, leaderEpoch = 0, offset =
2805, CreateTime = 1580719595164, serialized key size = 4, serialized value
size = 8, headers = RecordHeaders(headers = [], isReadOnly = false), key =
[B@6c779568, value = [B@f381794) expected <6069,17269> but was <6069,10698>
at
org.apache.kafka.streams.tests.EosTestDriver.verifySum(EosTestDriver.java:444)
at
org.apache.kafka.streams.tests.EosTestDriver.verify(EosTestDriver.java:196)
at
org.apache.kafka.streams.tests.StreamsEosTest.main(StreamsEosTest.java:69)
{code}
That means, the sum computed by the Streams app seems to be wrong for key 6069.
I checked the dumps of the log segments of the input topic partition (attached:
data-1.txt) and indeed two input records are not considered in the sum. With
those two missed records the sum would be correct. More concretely, the input
values for key 6069 are:
# 147
# 9250
# 5340
# 1231
# 1301
The sum of this values is 17269 as stated in the exception above as expected
sum. If you subtract values 3 and 4, i.e., 5340 and 1231 from 17269, you get
10698 , which is the actual sum in the exception above. Somehow those two
values are missing.
In the log dump of the output topic partition (attached: sum-1.txt), the sum is
correct until the 4th value 1231 , i.e. 15968, then it is overwritten with
10698.
In the log dump of the changelog topic of the state store that stores the sum
(attached: 7-changelog-1.txt), the sum is also overwritten as in the output
topic.
I attached the logs of the three Streams instances involved.
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