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)