jeffkbkim commented on code in PR #12783: URL: https://github.com/apache/kafka/pull/12783#discussion_r1007536584
########## core/src/test/scala/integration/kafka/server/FetchFromFollowerIntegrationTest.scala: ########## @@ -0,0 +1,97 @@ +/** + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +package integration.kafka.server + +import kafka.server.{BaseFetchRequestTest, BrokerTopicStats, KafkaConfig} +import kafka.utils.{TestInfoUtils, TestUtils} +import org.apache.kafka.clients.admin.Admin +import org.apache.kafka.common.TopicPartition +import org.apache.kafka.common.protocol.ApiKeys +import org.junit.jupiter.api.{AfterEach, BeforeEach, Timeout} +import org.junit.jupiter.params.ParameterizedTest +import org.junit.jupiter.params.provider.ValueSource + +import java.util.Properties + +class FetchFromFollowerIntegrationTest extends BaseFetchRequestTest { + val numNodes = 2 + val numParts = 1 + val initialMessages = 100 + val nMessages = 100 + + val topic = "test-fetch-from-follower" + val leaderBrokerId = 0 + val followerBrokerId = 1 + var admin: Admin = null + + def overridingProps: Properties = { + val props = new Properties + props.put(KafkaConfig.NumPartitionsProp, numParts.toString) + + props + } + + override def generateConfigs: collection.Seq[KafkaConfig] = + TestUtils.createBrokerConfigs(numNodes, zkConnectOrNull, enableControlledShutdown = false, enableFetchFromFollower = true) + .map(KafkaConfig.fromProps(_, overridingProps)) + + @BeforeEach + def initializeFetchFromFollowerCluster(): Unit = { + // Create a 2 broker cluster where broker 0 is the leader and 1 is the follower. + + admin = TestUtils.createAdminClient(brokers, listenerName) + TestUtils.createTopicWithAdminRaw( + admin, + topic, + replicaAssignment = Map(0 -> Seq(leaderBrokerId, followerBrokerId)) + ) + TestUtils.generateAndProduceMessages(brokers, topic, initialMessages) + } + + @AfterEach + def close(): Unit = { + if (admin != null) { + admin.close() + } + } + + @ParameterizedTest(name = TestInfoUtils.TestWithParameterizedQuorumName) + @ValueSource(strings = Array("zk", "kraft")) + @Timeout(30) + def testFollowerCompleteDelayedPurgatoryOnReplication(quorum: String): Unit = { + TestUtils.generateAndProduceMessages(brokers, topic, nMessages) + // set fetch.max.wait.ms to a value (45 seconds) greater than the timeout (30 seconds) to ensure that the + // test only passes when the delayed fetch purgatory is completed after successfully replicating from the leader. + + val totalMessages = initialMessages + nMessages + val topicPartition = new TopicPartition(topic, 0) + val offsetMap = Map[TopicPartition, Long]( + topicPartition -> (totalMessages - 1) Review Comment: ok, looking deeper into this, here's my understanding as to why fetching offset 200 did not work: The log end offset points to the next offset the log will append a record, so technically it doesn't exist yet. furthermore, the high watermark is updated to the log end offset. in `Partition.maybeIncrementLeaderHW()`: ``` var newHighWatermark = leaderLogEndOffset ... leaderLog.maybeIncrementHighWatermark(newHighWatermark) ``` even if the fetch offset is equal to the high watermark, we cannot fetch it if the high watermark is pointing to the log end offset. this is done in DelayedFetch where we skip accumulating bytes `if (endOffset.messageOffset (LEO) == fetchOffset.messageOffset (fetch offset))` @dajac does that align with your understanding? -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: jira-unsubscr...@kafka.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
