[jira] [Created] (KAFKA-10123) Regression resetting offsets in consumer when fetching from old broker

["Jason Gustafson (Jira)" <ji...@apache.org>]

Jason Gustafson created KAFKA-10123:
---------------------------------------

             Summary: Regression resetting offsets in consumer when fetching from old broker
                 Key: KAFKA-10123
                 URL: https://issues.apache.org/jira/browse/KAFKA-10123
             Project: Kafka
          Issue Type: Bug
            Reporter: Jason Gustafson
            Assignee: David Arthur
             Fix For: 2.6.0


We saw this error in system tests:
{code}
java.lang.NullPointerException
        at org.apache.kafka.clients.consumer.internals.Fetcher.prepareFetchRequests(Fetcher.java:1111)
        at org.apache.kafka.clients.consumer.internals.Fetcher.sendFetches(Fetcher.java:246)
        at org.apache.kafka.clients.consumer.KafkaConsumer.pollForFetches(KafkaConsumer.java:1296)
        at org.apache.kafka.clients.consumer.KafkaConsumer.poll(KafkaConsumer.java:1248)
        at org.apache.kafka.clients.consumer.KafkaConsumer.poll(KafkaConsumer.java:1216)
        at kafka.tools.ConsoleConsumer$ConsumerWrapper.receive(ConsoleConsumer.scala:437)
        at kafka.tools.ConsoleConsumer$.process(ConsoleConsumer.scala:103)
        at kafka.tools.ConsoleConsumer$.run(ConsoleConsumer.scala:77)
        at kafka.tools.ConsoleConsumer$.main(ConsoleConsumer.scala:54)
        at kafka.tools.ConsoleConsumer.main(ConsoleConsumer.scala)
{code}

The logs should that the consumer was in the middle of an offset reset when this happened. We changed the logic in KAFKA-9724 to include the following check:
{code}
            NodeApiVersions nodeApiVersions = apiVersions.get(leaderAndEpoch.leader.get().idString());
            if (nodeApiVersions == null || hasUsableOffsetForLeaderEpochVersion(nodeApiVersions)) {
                return assignedState(tp).maybeValidatePosition(leaderAndEpoch);
            } else {
                // If the broker does not support a newer version of OffsetsForLeaderEpoch, we skip validation
                completeValidation(tp);
                return false;
            }
{code}

The problem seems to be the shortcut call to `completeValidation`, which executes the following logic:
{code}
            if (hasPosition()) {
                transitionState(FetchStates.FETCHING, () -> this.nextRetryTimeMs = null);
            }
{code}

We should be protected by the call to `hasPosition` here, but in the case of the `AWAIT_RESET` state, we are incorrectly returning true. This causes us to enter the `FETCHING` state without a position, which ultimately leads to the NPE.



--
This message was sent by Atlassian Jira
(v8.3.4#803005)