jeffkbkim commented on code in PR #12783: URL: https://github.com/apache/kafka/pull/12783#discussion_r1006315710
########## core/src/test/scala/integration/kafka/server/FetchFromFollowerIntegrationTest.scala: ########## @@ -0,0 +1,106 @@ +/** + * 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.integration.KafkaServerTestHarness +import kafka.server.KafkaConfig +import kafka.utils.{TestInfoUtils, TestUtils} +import org.apache.kafka.clients.admin.{Admin, NewPartitionReassignment} +import org.apache.kafka.common.{ElectionType, TopicPartition} +import org.junit.jupiter.api.Assertions.assertTrue +import org.junit.jupiter.api.{AfterEach, BeforeEach} +import org.junit.jupiter.params.ParameterizedTest +import org.junit.jupiter.params.provider.ValueSource + +import java.util.{Optional, Properties} +import scala.collection._ +import scala.jdk.CollectionConverters._ + +class FetchFromFollowerIntegrationTest extends KafkaServerTestHarness { + 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)) + + // Create a 2 broker cluster where broker 0 is the leader and 1 is the follower. + // Create a topic with a single partition. Access brokers via `brokers` + @BeforeEach + def initializeFetchFromFollowerCluster(): Unit = { + createTopic(topic, numParts, numNodes) + TestUtils.generateAndProduceMessages(brokers, topic, initialMessages) + + // Make broker 1 the follower + admin = TestUtils.createAdminClient(brokers, listenerName) + val topicDescription = TestUtils.describeTopic(admin, topic) + topicDescription.partitions.forEach(partition => { + // only reelect if leader is not broker 0 + if (partition.leader().id() != leaderBrokerId) { + val reassignment = Map(new TopicPartition(topic, 0) -> Optional.of( + new NewPartitionReassignment(List[Integer](leaderBrokerId, followerBrokerId).asJava))).asJava + admin.alterPartitionReassignments(reassignment).all.get + TestUtils.waitUntilTrue(() => { + val reassigned = admin.listPartitionReassignments.reassignments.get + reassigned.isEmpty + }, "reassignment did not complete.") + admin.electLeaders(ElectionType.PREFERRED, Set(new TopicPartition(topic, 0)).asJava).all.get + } + }) + + // Check the log size for each broker so that we can distinguish between failures caused by replication issues + // versus failures caused by the metrics + val topicPartition = new TopicPartition(topic, 0) + brokers.foreach { broker => + val log = broker.logManager.getLog(topicPartition) + val brokerId = broker.config.brokerId + val logSize = log.map(_.size) + assertTrue(logSize.exists(_ > 0), s"Expected broker $brokerId to have a Log for $topicPartition with positive size, actual: $logSize") + } + } + + @AfterEach + def close(): Unit = { + if (admin != null) { + admin.close() + } + } + + @ParameterizedTest(name = TestInfoUtils.TestWithParameterizedQuorumName) + @ValueSource(strings = Array("zk", "kraft")) + def testFollowerCompleteDelayedPurgatoryOnReplication(quorum: String): Unit = { + TestUtils.generateAndProduceMessages(brokers, topic, nMessages) + // set fetch.max.wait.ms to a value greater than test utils wait time (15 seconds) to ensure that the + // delayed fetch purgatory is completed after successfully replicating from the leader. + val messages = initialMessages + nMessages + TestUtils.consumeTopicRecords(brokers, topic, messages, rackId = followerBrokerId.toString, fetchMaxWaitMs = 60000) Review Comment: unrelated question: i was looking into verifying the follower's bytes out metric but was a bit confused. in https://github.com/apache/kafka/blob/trunk/core/src/test/scala/unit/kafka/metrics/MetricsTest.scala#L193 we set up a 2 broker cluster and access the bytes out metric using `TestUtils.meterCount()` which accesses the static yammer metrics registry. for integration tests, does this mean brokers' yammer metrics are merged together into one registry? -- This is an automated message from the Apache Git Service. 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