cmccabe commented on a change in pull request #10494: URL: https://github.com/apache/kafka/pull/10494#discussion_r632770796
########## File path: metadata/src/test/java/org/apache/kafka/controller/StripedReplicaPlacerTest.java ########## @@ -0,0 +1,182 @@ +/* + * 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 org.apache.kafka.controller; + +import org.apache.kafka.common.errors.InvalidReplicationFactorException; +import org.apache.kafka.controller.StripedReplicaPlacer.BrokerList; +import org.apache.kafka.controller.StripedReplicaPlacer.RackList; +import org.apache.kafka.metadata.UsableBroker; +import org.junit.jupiter.api.Test; +import org.junit.jupiter.api.Timeout; + +import java.util.Arrays; +import java.util.Collections; +import java.util.Optional; + +import static org.junit.jupiter.api.Assertions.assertEquals; +import static org.junit.jupiter.api.Assertions.assertThrows; + + +@Timeout(value = 40) +public class StripedReplicaPlacerTest { + /** + * Test that the BrokerList class works as expected. + */ + @Test + public void testBrokerList() { + assertEquals(0, BrokerList.EMPTY.size()); + assertEquals(-1, BrokerList.EMPTY.next(1)); + BrokerList brokers = new BrokerList().add(0).add(1).add(2).add(3); + assertEquals(4, brokers.size()); + assertEquals(0, brokers.next(0)); + assertEquals(1, brokers.next(0)); + assertEquals(2, brokers.next(0)); + assertEquals(3, brokers.next(0)); + assertEquals(-1, brokers.next(0)); + assertEquals(-1, brokers.next(0)); + assertEquals(1, brokers.next(1)); + assertEquals(2, brokers.next(1)); + assertEquals(3, brokers.next(1)); + assertEquals(0, brokers.next(1)); + assertEquals(-1, brokers.next(1)); + } + + /** + * Test that we perform striped replica placement as expected, and don't use the + * fenced replica if we don't have to. + */ + @Test + public void testAvoidFencedReplicaIfPossibleOnSingleRack() { + MockRandom random = new MockRandom(); + RackList rackList = new RackList(random, Arrays.asList( + new UsableBroker(3, Optional.empty(), false), + new UsableBroker(1, Optional.empty(), true), + new UsableBroker(0, Optional.empty(), false), + new UsableBroker(4, Optional.empty(), false), + new UsableBroker(2, Optional.empty(), false)).iterator()); + assertEquals(5, rackList.numTotalBrokers()); + assertEquals(4, rackList.numUnfencedBrokers()); + assertEquals(Collections.singletonList(Optional.empty()), rackList.rackNames()); + assertThrows(InvalidReplicationFactorException.class, () -> rackList.place(0)); + assertThrows(InvalidReplicationFactorException.class, () -> rackList.place(-1)); + assertEquals(Arrays.asList(3, 4, 0, 2), rackList.place(4)); + assertEquals(Arrays.asList(4, 0, 2, 3), rackList.place(4)); + assertEquals(Arrays.asList(0, 2, 3, 4), rackList.place(4)); + assertEquals(Arrays.asList(2, 3, 4, 0), rackList.place(4)); + assertEquals(Arrays.asList(0, 4, 3, 2), rackList.place(4)); + } + + /** + * Test that we will place on the fenced replica if we need to. + */ + @Test + public void testPlacementOnFencedReplicaOnSingleRack() { + MockRandom random = new MockRandom(); + RackList rackList = new RackList(random, Arrays.asList( + new UsableBroker(3, Optional.empty(), false), + new UsableBroker(1, Optional.empty(), true), + new UsableBroker(2, Optional.empty(), false)).iterator()); + assertEquals(3, rackList.numTotalBrokers()); + assertEquals(2, rackList.numUnfencedBrokers()); + assertEquals(Collections.singletonList(Optional.empty()), rackList.rackNames()); + assertEquals(Arrays.asList(3, 2, 1), rackList.place(3)); + assertEquals(Arrays.asList(2, 3, 1), rackList.place(3)); + assertEquals(Arrays.asList(3, 2, 1), rackList.place(3)); + assertEquals(Arrays.asList(2, 3, 1), rackList.place(3)); + } + + @Test + public void testRackListWithMultipleRacks() { + MockRandom random = new MockRandom(); + RackList rackList = new RackList(random, Arrays.asList( + new UsableBroker(11, Optional.of("1"), false), + new UsableBroker(10, Optional.of("1"), false), + new UsableBroker(30, Optional.of("3"), false), + new UsableBroker(31, Optional.of("3"), false), + new UsableBroker(21, Optional.of("2"), false), + new UsableBroker(20, Optional.of("2"), true)).iterator()); + assertEquals(6, rackList.numTotalBrokers()); + assertEquals(5, rackList.numUnfencedBrokers()); + assertEquals(Arrays.asList(Optional.of("1"), Optional.of("2"), Optional.of("3")), rackList.rackNames()); + assertEquals(Arrays.asList(11, 21, 31, 10), rackList.place(4)); + assertEquals(Arrays.asList(21, 30, 10, 20), rackList.place(4)); + assertEquals(Arrays.asList(31, 11, 21, 30), rackList.place(4)); + } + + @Test + public void testRackListWithInvalidRacks() { + MockRandom random = new MockRandom(); + RackList rackList = new RackList(random, Arrays.asList( + new UsableBroker(11, Optional.of("1"), false), + new UsableBroker(10, Optional.of("1"), false), + new UsableBroker(30, Optional.of("3"), true), + new UsableBroker(31, Optional.of("3"), true), + new UsableBroker(20, Optional.of("2"), true), + new UsableBroker(21, Optional.of("2"), true), + new UsableBroker(41, Optional.of("4"), false), + new UsableBroker(40, Optional.of("4"), true)).iterator()); + assertEquals(8, rackList.numTotalBrokers()); + assertEquals(3, rackList.numUnfencedBrokers()); + assertEquals(Arrays.asList(Optional.of("1"), + Optional.of("2"), + Optional.of("3"), + Optional.of("4")), rackList.rackNames()); + assertEquals(Arrays.asList(41, 11, 21, 30), rackList.place(4)); Review comment: > Why didn't the leader start from rack 1, which is the fist in the rack list? The starting rack is randomized. If the first partition always put its leader on a specific rack, that would create skew, since a lot of topics are created with only one or two partitions. > Also, why didn't rack 2 start with 20, which sorts first during initialization? `BrokerList#offset` is also randomized, for the same reason (to avoid favoring replicas with a lower id) -- 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. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
