Description
We saw this error in system tests:
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)
The logs showed that the consumer was in the middle of an offset reset when this happened. We changed the validation logic in KAFKA-9724 to include the following check with the intent of skipping validation for old brokers:
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; }
The problem seems to be the shortcut call to `completeValidation`, which executes the following logic:
if (hasPosition()) { transitionState(FetchStates.FETCHING, () -> this.nextRetryTimeMs = null); }
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.
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KAFKA-10119 StreamsResetter fails with TimeoutException for older Brokers
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