[jira] [Created] (KAFKA-9572) Sum Computation with Exactly-Once Enabled and Injected Failures Misses Some Records

["Bruno Cadonna (Jira)" <ji...@apache.org>]

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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