[GitHub] [storm] Ethanlm commented on a change in pull request #3379: [STORM-3739] Scheduling should sort numa zones by host groups

[GitBox <gi...@apache.org>]

Ethanlm commented on a change in pull request #3379:
URL: https://github.com/apache/storm/pull/3379#discussion_r590746755



##########
File path: storm-server/src/main/java/org/apache/storm/scheduler/resource/strategies/scheduling/sorter/NodeSorterHostProximity.java
##########
@@ -0,0 +1,712 @@
+/*
+ * 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.storm.scheduler.resource.strategies.scheduling.sorter;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.NoSuchElementException;
+import java.util.Set;
+import java.util.TreeSet;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+import org.apache.storm.Config;
+import org.apache.storm.networktopography.DNSToSwitchMapping;
+import org.apache.storm.scheduler.Cluster;
+import org.apache.storm.scheduler.ExecutorDetails;
+import org.apache.storm.scheduler.SchedulerAssignment;
+import org.apache.storm.scheduler.TopologyDetails;
+import org.apache.storm.scheduler.WorkerSlot;
+import org.apache.storm.scheduler.resource.RasNode;
+import org.apache.storm.scheduler.resource.RasNodes;
+import org.apache.storm.scheduler.resource.normalization.NormalizedResourceOffer;
+import org.apache.storm.scheduler.resource.normalization.NormalizedResourceRequest;
+import org.apache.storm.scheduler.resource.strategies.scheduling.BaseResourceAwareStrategy;
+import org.apache.storm.scheduler.resource.strategies.scheduling.ObjectResourcesItem;
+import org.apache.storm.scheduler.resource.strategies.scheduling.ObjectResourcesSummary;
+import org.apache.storm.shade.com.google.common.annotations.VisibleForTesting;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class NodeSorterHostProximity implements INodeSorter {
+    private static final Logger LOG = LoggerFactory.getLogger(NodeSorterHostProximity.class);
+
+    // instance variables from class instantiation
+    protected final BaseResourceAwareStrategy.NodeSortType nodeSortType;
+
+    protected Cluster cluster;
+    protected TopologyDetails topologyDetails;
+
+    // Instance variables derived from Cluster.
+    private final Map<String, List<String>> networkTopography;

Review comment:
       This doesn't seem to be used anywhere. It can be removed.

##########
File path: storm-server/src/main/java/org/apache/storm/scheduler/resource/strategies/scheduling/sorter/NodeSorterHostProximity.java
##########
@@ -0,0 +1,712 @@
+/*
+ * 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.storm.scheduler.resource.strategies.scheduling.sorter;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.NoSuchElementException;
+import java.util.Set;
+import java.util.TreeSet;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+import org.apache.storm.Config;
+import org.apache.storm.networktopography.DNSToSwitchMapping;
+import org.apache.storm.scheduler.Cluster;
+import org.apache.storm.scheduler.ExecutorDetails;
+import org.apache.storm.scheduler.SchedulerAssignment;
+import org.apache.storm.scheduler.TopologyDetails;
+import org.apache.storm.scheduler.WorkerSlot;
+import org.apache.storm.scheduler.resource.RasNode;
+import org.apache.storm.scheduler.resource.RasNodes;
+import org.apache.storm.scheduler.resource.normalization.NormalizedResourceOffer;
+import org.apache.storm.scheduler.resource.normalization.NormalizedResourceRequest;
+import org.apache.storm.scheduler.resource.strategies.scheduling.BaseResourceAwareStrategy;
+import org.apache.storm.scheduler.resource.strategies.scheduling.ObjectResourcesItem;
+import org.apache.storm.scheduler.resource.strategies.scheduling.ObjectResourcesSummary;
+import org.apache.storm.shade.com.google.common.annotations.VisibleForTesting;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class NodeSorterHostProximity implements INodeSorter {
+    private static final Logger LOG = LoggerFactory.getLogger(NodeSorterHostProximity.class);
+
+    // instance variables from class instantiation
+    protected final BaseResourceAwareStrategy.NodeSortType nodeSortType;
+
+    protected Cluster cluster;
+    protected TopologyDetails topologyDetails;
+
+    // Instance variables derived from Cluster.
+    private final Map<String, List<String>> networkTopography;
+    private final Map<String, String> superIdToRack = new HashMap<>();
+    private final Map<String, List<RasNode>> hostnameToNodes = new HashMap<>();
+    private final Map<String, String> nodeIdToHostname = new HashMap<>();
+    private final Map<String, Set<String>> rackIdToHosts = new HashMap<>();
+    protected List<String> greyListedSupervisorIds;
+
+    // Instance variables from Cluster and TopologyDetails.
+    protected List<String> favoredNodeIds;
+    protected List<String> unFavoredNodeIds;
+
+    // Updated in prepare method
+    ExecutorDetails exec;
+
+    public NodeSorterHostProximity(Cluster cluster, TopologyDetails topologyDetails) {
+        this(cluster, topologyDetails, BaseResourceAwareStrategy.NodeSortType.COMMON);
+    }
+
+    /**
+     * Initialize for the default implementation node sorting.
+     *
+     * <p>
+     *  <li>{@link BaseResourceAwareStrategy.NodeSortType#GENERIC_RAS} sorting implemented in
+     *  {@link #sortObjectResourcesGeneric(ObjectResourcesSummary, ExecutorDetails, NodeSorterHostProximity.ExistingScheduleFunc)}</li>
+     *  <li>{@link BaseResourceAwareStrategy.NodeSortType#DEFAULT_RAS} sorting implemented in
+     *  {@link #sortObjectResourcesDefault(ObjectResourcesSummary, NodeSorterHostProximity.ExistingScheduleFunc)}</li>
+     *  <li>{@link BaseResourceAwareStrategy.NodeSortType#COMMON} sorting implemented in
+     *  {@link #sortObjectResourcesCommon(ObjectResourcesSummary, ExecutorDetails, NodeSorterHostProximity.ExistingScheduleFunc)}</li>
+     * </p>
+     *
+     * @param cluster for which nodes will be sorted.
+     * @param topologyDetails the topology to sort for.
+     * @param nodeSortType type of sorting to be applied to object resource collection {@link BaseResourceAwareStrategy.NodeSortType}.
+     */
+    public NodeSorterHostProximity(Cluster cluster, TopologyDetails topologyDetails, BaseResourceAwareStrategy.NodeSortType nodeSortType) {
+        this.cluster = cluster;
+        this.topologyDetails = topologyDetails;
+        this.nodeSortType = nodeSortType;
+
+        // from Cluster
+        networkTopography = cluster.getNetworkTopography();
+        greyListedSupervisorIds = cluster.getGreyListedSupervisors();
+        Map<String, String> hostToRack = cluster.getHostToRack();
+        RasNodes nodes = new RasNodes(cluster);
+        for (RasNode node: nodes.getNodes()) {
+            String superId = node.getId();
+            String hostName = node.getHostname();
+            if (!node.isAlive() || hostName == null) {
+                continue;
+            }
+            String rackId = hostToRack.getOrDefault(hostName, DNSToSwitchMapping.DEFAULT_RACK);
+            superIdToRack.put(superId, rackId);
+            hostnameToNodes.computeIfAbsent(hostName, (hn) -> new ArrayList<>()).add(node);
+            nodeIdToHostname.put(superId, hostName);
+            rackIdToHosts.computeIfAbsent(rackId, r -> new HashSet<>()).add(hostName);
+        }
+
+        // from TopologyDetails
+        Map<String, Object> topoConf = topologyDetails.getConf();
+
+        // From Cluster and TopologyDetails - and cleaned-up
+        favoredNodeIds = makeHostToNodeIds((List<String>) topoConf.get(Config.TOPOLOGY_SCHEDULER_FAVORED_NODES));
+        unFavoredNodeIds = makeHostToNodeIds((List<String>) topoConf.get(Config.TOPOLOGY_SCHEDULER_UNFAVORED_NODES));
+        favoredNodeIds.removeAll(greyListedSupervisorIds);
+        unFavoredNodeIds.removeAll(greyListedSupervisorIds);
+        unFavoredNodeIds.removeAll(favoredNodeIds);
+    }
+
+    @VisibleForTesting
+    public Map<String, Set<String>> getRackIdToHosts() {
+        return rackIdToHosts;
+    }
+
+    @Override
+    public void prepare(ExecutorDetails exec) {
+        this.exec = exec;
+    }
+
+    /**
+     * Scheduling uses {@link #sortAllNodes()} which eventually
+     * calls this method whose behavior can altered by setting {@link #nodeSortType}.

Review comment:
       nit : can be altered

##########
File path: storm-server/src/test/java/org/apache/storm/scheduler/resource/strategies/scheduling/sorter/TestNodeSorterHostProximity.java
##########
@@ -0,0 +1,1054 @@
+/*
+ * 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
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.storm.scheduler.resource.strategies.scheduling.sorter;
+
+import org.apache.logging.log4j.Level;
+import org.apache.logging.log4j.core.config.Configurator;
+import org.apache.storm.Config;
+import org.apache.storm.metric.StormMetricsRegistry;
+import org.apache.storm.networktopography.DNSToSwitchMapping;
+import org.apache.storm.scheduler.Cluster;
+import org.apache.storm.scheduler.ExecutorDetails;
+import org.apache.storm.scheduler.INimbus;
+import org.apache.storm.scheduler.IScheduler;
+import org.apache.storm.scheduler.SchedulerAssignment;
+import org.apache.storm.scheduler.SupervisorDetails;
+import org.apache.storm.scheduler.Topologies;
+import org.apache.storm.scheduler.TopologyDetails;
+import org.apache.storm.scheduler.WorkerSlot;
+import org.apache.storm.scheduler.resource.RasNodes;
+import org.apache.storm.scheduler.resource.ResourceAwareScheduler;
+import org.apache.storm.scheduler.resource.TestUtilsForResourceAwareScheduler;
+import org.apache.storm.scheduler.resource.normalization.NormalizedResourceRequest;
+import org.apache.storm.scheduler.resource.normalization.NormalizedResourcesExtension;
+import org.apache.storm.scheduler.resource.normalization.ResourceMetrics;
+import org.apache.storm.scheduler.resource.strategies.scheduling.BaseResourceAwareStrategy;
+import org.apache.storm.scheduler.resource.strategies.scheduling.DefaultResourceAwareStrategy;
+import org.apache.storm.scheduler.resource.strategies.scheduling.GenericResourceAwareStrategy;
+import org.apache.storm.scheduler.resource.strategies.scheduling.ObjectResourcesItem;
+import org.apache.storm.topology.TopologyBuilder;
+import org.junit.Assert;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeMap;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.stream.Collectors;
+import java.util.stream.StreamSupport;
+
+import static org.apache.storm.scheduler.resource.TestUtilsForResourceAwareScheduler.*;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+@ExtendWith({NormalizedResourcesExtension.class})
+public class TestNodeSorterHostProximity {
+    private static final Logger LOG = LoggerFactory.getLogger(TestNodeSorterHostProximity.class);
+    private static final int CURRENT_TIME = 1450418597;
+
+    protected Class getDefaultResourceAwareStrategyClass() {
+        return DefaultResourceAwareStrategy.class;
+    }
+
+    private Config createClusterConfig(double compPcore, double compOnHeap, double compOffHeap,
+                                       Map<String, Map<String, Number>> pools) {
+        Config config = TestUtilsForResourceAwareScheduler.createClusterConfig(compPcore, compOnHeap, compOffHeap, pools);
+        config.put(Config.TOPOLOGY_SCHEDULER_STRATEGY, getDefaultResourceAwareStrategyClass().getName());
+        return config;
+    }
+
+    private static class TestDNSToSwitchMapping implements DNSToSwitchMapping {
+        private final Map<String, String> hostToRackMap;
+        private final Map<String, List<String>> rackToHosts;
+
+        @SafeVarargs
+        public TestDNSToSwitchMapping(Map<String, SupervisorDetails>... racks) {
+            Set<String> seenHosts = new HashSet<>();
+            Map<String, String> hostToRackMap = new HashMap<>();
+            Map<String, List<String>> rackToHosts = new HashMap<>();
+            for (int rackNum = 0; rackNum < racks.length; rackNum++) {
+                String rack = String.format("rack-%03d", rackNum);
+                for (SupervisorDetails sup : racks[rackNum].values()) {
+                    hostToRackMap.put(sup.getHost(), rack);
+                    String host = sup.getHost();
+                    if (!seenHosts.contains(host)) {
+                        rackToHosts.computeIfAbsent(rack, rid -> new ArrayList<>()).add(host);
+                        seenHosts.add(host);
+                    }
+                }
+            }
+            this.hostToRackMap = Collections.unmodifiableMap(hostToRackMap);
+            this.rackToHosts = Collections.unmodifiableMap(rackToHosts);
+        }
+
+        /**
+         * Use the "rack-%03d" embedded in the name of the supervisor to determine the rack number.
+         *
+         * @param supervisorDetailsCollection
+         */
+        public TestDNSToSwitchMapping(Collection<SupervisorDetails> supervisorDetailsCollection) {
+            Set<String> seenHosts = new HashSet<>();
+            Map<String, String> hostToRackMap = new HashMap<>();
+            Map<String, List<String>> rackToHosts = new HashMap<>();
+
+            for (SupervisorDetails supervisorDetails: supervisorDetailsCollection) {
+                String rackId = supervisorIdToRackName(supervisorDetails.getId());
+                hostToRackMap.put(supervisorDetails.getHost(), rackId);
+                String host = supervisorDetails.getHost();
+                if (!seenHosts.contains(host)) {
+                    rackToHosts.computeIfAbsent(rackId, rid -> new ArrayList<>()).add(host);
+                    seenHosts.add(host);
+                }
+            }
+            this.hostToRackMap = Collections.unmodifiableMap(hostToRackMap);
+            this.rackToHosts = Collections.unmodifiableMap(rackToHosts);
+        }
+
+        @Override
+        public Map<String, String> resolve(List<String> names) {
+            return hostToRackMap;
+        }
+
+        public Map<String, List<String>> getRackToHosts() {
+            return rackToHosts;
+        }
+    }
+
+    /**
+     * Test whether strategy will choose correct rack.
+     */
+    @Test
+    public void testMultipleRacks() {
+        final Map<String, SupervisorDetails> supMap = new HashMap<>();
+        final int numRacks = 1;
+        final int numSupersPerRack = 10;
+        final int numPortsPerSuper = 4;
+        final int numZonesPerHost = 1;
+        final double numaResourceMultiplier = 1.0;
+        int rackStartNum = 0;
+        int supStartNum = 0;
+
+        final Map<String, SupervisorDetails> supMapRack0 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400, 8000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate another rack of supervisors with less resources
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack1 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                200, 4000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate some supervisors that are depleted of one resource
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack2 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                0, 8000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate some that has a lot of memory but little of cpu
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack3 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                10, 8000 * 2 + 4000, Collections.emptyMap(),numaResourceMultiplier);
+
+        //generate some that has a lot of cpu but little of memory
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack4 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400 + 200 + 10, 1000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //Generate some that have neither resource, to verify that the strategy will prioritize this last
+        //Also put a generic resource with 0 value in the resources list, to verify that it doesn't affect the sorting
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack5 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                0.0, 0.0, Collections.singletonMap("gpu.count", 0.0), numaResourceMultiplier);
+
+        supMap.putAll(supMapRack0);
+        supMap.putAll(supMapRack1);
+        supMap.putAll(supMapRack2);
+        supMap.putAll(supMapRack3);
+        supMap.putAll(supMapRack4);
+        supMap.putAll(supMapRack5);
+
+        Config config = createClusterConfig(100, 500, 500, null);
+        config.put(Config.TOPOLOGY_WORKER_MAX_HEAP_SIZE_MB, Double.MAX_VALUE);
+        INimbus iNimbus = new INimbusTest();
+
+        //create test DNSToSwitchMapping plugin
+        TestDNSToSwitchMapping testDNSToSwitchMapping =
+                new TestDNSToSwitchMapping(supMapRack0, supMapRack1, supMapRack2, supMapRack3, supMapRack4, supMapRack5);
+
+        //generate topologies
+        TopologyDetails topo1 = genTopology("topo-1", config, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+        TopologyDetails topo2 = genTopology("topo-2", config, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+        Topologies topologies = new Topologies(topo1, topo2);
+        Cluster cluster = new Cluster(iNimbus, new ResourceMetrics(new StormMetricsRegistry()), supMap, new HashMap<>(), topologies, config);
+
+        List<String> supHostnames = new LinkedList<>();
+        for (SupervisorDetails sup : supMap.values()) {
+            supHostnames.add(sup.getHost());
+        }
+        Map<String, List<String>> rackToHosts = testDNSToSwitchMapping.getRackToHosts();
+        cluster.setNetworkTopography(rackToHosts);
+        System.out.println("DEBUG: rackToHosts: " + rackToHosts.toString());
+
+        NodeSorterHostProximity nodeSorter = new NodeSorterHostProximity(cluster, topo1, BaseResourceAwareStrategy.NodeSortType.DEFAULT_RAS);
+        nodeSorter.prepare(null);
+        List<ObjectResourcesItem> sortedRacks = StreamSupport.stream(nodeSorter.getSortedRacks().spliterator(), false)
+                .collect(Collectors.toList());
+        String rackSummaries = sortedRacks.stream()
+                .map(x -> String.format("Rack %s -> scheduled-cnt %d, min-avail %f, avg-avail %f, cpu %f, mem %f",
+                        x.id, nodeSorter.getScheduledExecCntByRackId().getOrDefault(x.id, new AtomicInteger(-1)).get(),
+                        x.minResourcePercent, x.avgResourcePercent,
+                        x.availableResources.getTotalCpu(),
+                        x.availableResources.getTotalMemoryMb()))
+                .collect(Collectors.joining("\n\t"));
+        Assert.assertEquals(rackSummaries + "\n# of racks sorted", 6, sortedRacks.size());
+        Iterator<ObjectResourcesItem> it = sortedRacks.iterator();
+        Assert.assertEquals(rackSummaries + "\nrack-000 should be ordered first since it has the most balanced set of resources", "rack-000", it.next().id);
+        Assert.assertEquals(rackSummaries + "\nrack-001 should be ordered second since it has a balanced set of resources but less than rack-000", "rack-001", it.next().id);
+        Assert.assertEquals(rackSummaries + "\nrack-004 should be ordered third since it has a lot of cpu but not a lot of memory", "rack-004", it.next().id);
+        Assert.assertEquals(rackSummaries + "\nrack-003 should be ordered fourth since it has a lot of memory but not cpu", "rack-003", it.next().id);
+        Assert.assertEquals(rackSummaries + "\nrack-002 should be ordered fifth since it has not cpu resources", "rack-002", it.next().id);
+        Assert.assertEquals(rackSummaries + "\nRack-005 should be ordered sixth since it has neither CPU nor memory available", "rack-005", it.next().id);
+    }
+
+    /**
+     * Test whether strategy will choose correct rack.
+     */
+    @Test
+    public void testMultipleRacksWithFavoritism() {
+        final Map<String, SupervisorDetails> supMap = new HashMap<>();
+        final int numRacks = 1;
+        final int numSupersPerRack = 10;
+        final int numPortsPerSuper = 4;
+        final int numZonesPerHost = 2;
+        int rackStartNum = 0;
+        int supStartNum = 0;
+        final Map<String, SupervisorDetails> supMapRack0 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400, 8000, Collections.emptyMap(), 1.0);
+
+        //generate another rack of supervisors with less resources
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack1 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                200, 4000, Collections.emptyMap(), 1.0);
+
+        //generate some supervisors that are depleted of one resource
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack2 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                0, 8000, Collections.emptyMap(), 1.0);
+
+        //generate some that has a lot of memory but little of cpu
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack3 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                10, 8000 * 2 + 4000, Collections.emptyMap(), 1.0);
+
+        //generate some that has a lot of cpu but little of memory
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack4 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400 + 200 + 10, 1000, Collections.emptyMap(), 1.0);
+
+        supMap.putAll(supMapRack0);
+        supMap.putAll(supMapRack1);
+        supMap.putAll(supMapRack2);
+        supMap.putAll(supMapRack3);
+        supMap.putAll(supMapRack4);
+
+        Config config = createClusterConfig(100, 500, 500, null);
+        config.put(Config.TOPOLOGY_WORKER_MAX_HEAP_SIZE_MB, Double.MAX_VALUE);
+        INimbus iNimbus = new INimbusTest();
+
+        //create test DNSToSwitchMapping plugin
+        TestDNSToSwitchMapping testDNSToSwitchMapping =
+                new TestDNSToSwitchMapping(supMapRack0, supMapRack1, supMapRack2, supMapRack3, supMapRack4);
+
+        Config t1Conf = new Config();
+        t1Conf.putAll(config);
+        final List<String> t1FavoredHostNames = Arrays.asList("host-41", "host-42", "host-43");
+        t1Conf.put(Config.TOPOLOGY_SCHEDULER_FAVORED_NODES, t1FavoredHostNames);
+        final List<String> t1UnfavoredHostIds = Arrays.asList("host-1", "host-2", "host-3");
+        t1Conf.put(Config.TOPOLOGY_SCHEDULER_UNFAVORED_NODES, t1UnfavoredHostIds);
+        //generate topologies
+        TopologyDetails topo1 = genTopology("topo-1", t1Conf, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+
+        Config t2Conf = new Config();
+        t2Conf.putAll(config);
+        t2Conf.put(Config.TOPOLOGY_SCHEDULER_FAVORED_NODES, Arrays.asList("host-31", "host-32", "host-33"));
+        t2Conf.put(Config.TOPOLOGY_SCHEDULER_UNFAVORED_NODES, Arrays.asList("host-11", "host-12", "host-13"));
+        TopologyDetails topo2 = genTopology("topo-2", t2Conf, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+        Topologies topologies = new Topologies(topo1, topo2);
+        Cluster cluster = new Cluster(iNimbus, new ResourceMetrics(new StormMetricsRegistry()), supMap, new HashMap<>(), topologies, config);
+
+        List<String> supHostnames = new LinkedList<>();
+        for (SupervisorDetails sup : supMap.values()) {
+            supHostnames.add(sup.getHost());
+        }
+        Map<String, List<String>> rackToHosts = testDNSToSwitchMapping.getRackToHosts();
+        cluster.setNetworkTopography(rackToHosts);
+
+        NodeSorterHostProximity nodeSorter = new NodeSorterHostProximity(cluster, topo1, BaseResourceAwareStrategy.NodeSortType.DEFAULT_RAS);
+        nodeSorter.prepare(null);
+        List<ObjectResourcesItem> sortedRacks = StreamSupport.stream(nodeSorter.getSortedRacks().spliterator(), false)
+                .collect(Collectors.toList());
+        String rackSummaries = sortedRacks.stream()
+                .map(x -> String.format("Rack %s -> scheduled-cnt %d, min-avail %f, avg-avail %f, cpu %f, mem %f",
+                        x.id, nodeSorter.getScheduledExecCntByRackId().getOrDefault(x.id, new AtomicInteger(-1)).get(),
+                        x.minResourcePercent, x.avgResourcePercent,
+                        x.availableResources.getTotalCpu(),
+                        x.availableResources.getTotalMemoryMb()))
+                .collect(Collectors.joining("\n\t"));
+
+        Iterator<ObjectResourcesItem> it = sortedRacks.iterator();
+        // Ranked first since rack-000 has the most balanced set of resources
+        Assert.assertEquals("rack-000 should be ordered first", "rack-000", it.next().id);
+        // Ranked second since rack-1 has a balanced set of resources but less than rack-0
+        Assert.assertEquals("rack-001 should be ordered second", "rack-001", it.next().id);
+        // Ranked third since rack-4 has a lot of cpu but not a lot of memory
+        Assert.assertEquals("rack-004 should be ordered third", "rack-004", it.next().id);
+        // Ranked fourth since rack-3 has alot of memory but not cpu
+        Assert.assertEquals("rack-003 should be ordered fourth", "rack-003", it.next().id);
+        //Ranked last since rack-2 has not cpu resources
+        Assert.assertEquals("rack-00s2 should be ordered fifth", "rack-002", it.next().id);
+    }
+
+    /**
+     * Test if hosts are presented together regardless of resource availability.
+     * Supervisors are created with multiple Numa zones in such a manner that resources on two numa zones on the same host
+     * differ widely in resource availability.
+     */
+    @Test
+    public void testMultipleRacksWithHostProximity() {
+        final Map<String, SupervisorDetails> supMap = new HashMap<>();
+        final int numRacks = 1;
+        final int numSupersPerRack = 12;
+        final int numPortsPerSuper = 4;
+        final int numZonesPerHost = 3;
+        final double numaResourceMultiplier = 0.4;
+        int rackStartNum = 0;
+        int supStartNum = 0;
+
+        final Map<String, SupervisorDetails> supMapRack0 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400, 8000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate another rack of supervisors with less resources
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack1 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                200, 4000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate some supervisors that are depleted of one resource
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack2 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                0, 8000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate some that has a lot of memory but little of cpu
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack3 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                10, 8000 * 2 + 4000, Collections.emptyMap(),numaResourceMultiplier);
+
+        //generate some that has a lot of cpu but little of memory
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack4 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400 + 200 + 10, 1000, Collections.emptyMap(), numaResourceMultiplier);
+
+        supMap.putAll(supMapRack0);
+        supMap.putAll(supMapRack1);
+        supMap.putAll(supMapRack2);
+        supMap.putAll(supMapRack3);
+        supMap.putAll(supMapRack4);
+
+        Config config = createClusterConfig(100, 500, 500, null);
+        config.put(Config.TOPOLOGY_WORKER_MAX_HEAP_SIZE_MB, Double.MAX_VALUE);
+        INimbus iNimbus = new INimbusTest();
+
+        //create test DNSToSwitchMapping plugin
+        TestDNSToSwitchMapping testDNSToSwitchMapping =
+                new TestDNSToSwitchMapping(supMapRack0, supMapRack1, supMapRack2, supMapRack3, supMapRack4);
+
+        Config t1Conf = new Config();
+        t1Conf.putAll(config);
+        final List<String> t1FavoredHostNames = Arrays.asList("host-41", "host-42", "host-43");
+        t1Conf.put(Config.TOPOLOGY_SCHEDULER_FAVORED_NODES, t1FavoredHostNames);
+        final List<String> t1UnfavoredHostIds = Arrays.asList("host-1", "host-2", "host-3");
+        t1Conf.put(Config.TOPOLOGY_SCHEDULER_UNFAVORED_NODES, t1UnfavoredHostIds);
+        //generate topologies
+        TopologyDetails topo1 = genTopology("topo-1", t1Conf, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+
+        Config t2Conf = new Config();
+        t2Conf.putAll(config);
+        t2Conf.put(Config.TOPOLOGY_SCHEDULER_FAVORED_NODES, Arrays.asList("host-31", "host-32", "host-33"));
+        t2Conf.put(Config.TOPOLOGY_SCHEDULER_UNFAVORED_NODES, Arrays.asList("host-11", "host-12", "host-13"));
+        TopologyDetails topo2 = genTopology("topo-2", t2Conf, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+        Topologies topologies = new Topologies(topo1, topo2);
+        Cluster cluster = new Cluster(iNimbus, new ResourceMetrics(new StormMetricsRegistry()), supMap, new HashMap<>(), topologies, config);
+
+        cluster.setNetworkTopography(testDNSToSwitchMapping.getRackToHosts());
+
+        INodeSorter nodeSorter = new NodeSorterHostProximity(cluster, topo1);
+        nodeSorter.prepare(null);
+
+        Set<String> seenHosts = new HashSet<>();
+        String prevHost = null;
+        List<String> errLines = new ArrayList();
+        Map<String, String> nodeToHost = new RasNodes(cluster).getNodeIdToHostname();
+        for (String nodeId: nodeSorter.sortAllNodes()) {
+            String host = nodeToHost.getOrDefault(nodeId, "no-host-for-node-" + nodeId);
+            errLines.add(String.format("\tnodeId:%s, host:%s", nodeId, host));
+            if (!host.equals(prevHost) && seenHosts.contains(host)) {
+                String err = String.format("Host %s for node %s is out of order:\n\t%s", host, nodeId, String.join("\n\t", errLines));
+                Assert.fail(err);
+            }
+            seenHosts.add(host);
+            prevHost = host;
+        }
+        System.out.printf("DEBUG: Test Success: Hosts are listed together:\n\t%s\n", String.join("\n\t", errLines));
+    }
+
+    /**
+     * Racks should be returned in order of decreasing capacity.
+     */
+    @Test
+    public void testMultipleRacksOrderedByCapacity() {
+        final Map<String, SupervisorDetails> supMap = new HashMap<>();
+        final int numRacks = 1;
+        final int numSupersPerRack = 10;
+        final int numPortsPerSuper = 4;
+        final int numZonesPerHost = 1;
+        final double numaResourceMultiplier = 1.0;
+        int rackStartNum = 0;
+        int supStartNum = 0;
+
+        final Map<String, SupervisorDetails> supMapRack0 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                600, 8000 - rackStartNum, Collections.emptyMap(), numaResourceMultiplier);
+
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack1 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                500, 8000 - rackStartNum, Collections.emptyMap(), numaResourceMultiplier);
+
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack2 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400, 8000 - rackStartNum, Collections.emptyMap(), numaResourceMultiplier);
+
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack3 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                300, 8000 - rackStartNum, Collections.emptyMap(),numaResourceMultiplier);
+
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack4 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                200, 8000 - rackStartNum, Collections.emptyMap(), numaResourceMultiplier);
+
+        // too small to hold topology
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack5 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                100, 8000 - rackStartNum, Collections.singletonMap("gpu.count", 0.0), numaResourceMultiplier);
+
+        supMap.putAll(supMapRack0);
+        supMap.putAll(supMapRack1);
+        supMap.putAll(supMapRack2);
+        supMap.putAll(supMapRack3);
+        supMap.putAll(supMapRack4);
+        supMap.putAll(supMapRack5);
+
+        Config config = createClusterConfig(100, 500, 500, null);
+        config.put(Config.TOPOLOGY_WORKER_MAX_HEAP_SIZE_MB, Double.MAX_VALUE);
+        INimbus iNimbus = new INimbusTest();
+
+        //create test DNSToSwitchMapping plugin
+        TestDNSToSwitchMapping testDNSToSwitchMapping =
+                new TestDNSToSwitchMapping(supMapRack0, supMapRack1, supMapRack2, supMapRack3, supMapRack4, supMapRack5);
+
+        //generate topologies
+        TopologyDetails topo1 = genTopology("topo-1", config, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+        TopologyDetails topo2 = genTopology("topo-2", config, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+        Topologies topologies = new Topologies(topo1, topo2);
+        Cluster cluster = new Cluster(iNimbus, new ResourceMetrics(new StormMetricsRegistry()), supMap, new HashMap<>(), topologies, config);
+
+        cluster.setNetworkTopography(testDNSToSwitchMapping.getRackToHosts());
+
+        NodeSorterHostProximity nodeSorter = new NodeSorterHostProximity(cluster, topo1);
+        nodeSorter.prepare(null);
+        List<ObjectResourcesItem> sortedRacks = StreamSupport.stream(nodeSorter.getSortedRacks().spliterator(), false)
+                .collect(Collectors.toList());
+        String rackSummaries = sortedRacks
+                .stream()
+                .map(x -> String.format("Rack %s -> scheduled-cnt %d, min-avail %f, avg-avail %f, cpu %f, mem %f",
+                        x.id, nodeSorter.getScheduledExecCntByRackId().getOrDefault(x.id, new AtomicInteger(-1)).get(),
+                        x.minResourcePercent, x.avgResourcePercent,
+                        x.availableResources.getTotalCpu(),
+                        x.availableResources.getTotalMemoryMb()))
+                .collect(Collectors.joining("\n\t"));
+        NormalizedResourceRequest topoResourceRequest = topo1.getApproximateTotalResources();
+        String topoRequest = String.format("Topo %s, approx-requested-resources %s", topo1.getId(), topoResourceRequest.toString());
+        //Assert.assertEquals(rackSummaries + "\n# of racks sorted", 6, sortedRacks.size());

Review comment:
       Remove unused code; or uncomment it if it is used. 
   Looks like we should keep it.

##########
File path: storm-server/src/main/java/org/apache/storm/scheduler/resource/strategies/scheduling/sorter/NodeSorter.java
##########
@@ -122,16 +122,21 @@ public NodeSorter(Cluster cluster, TopologyDetails topologyDetails, BaseResource
         unFavoredNodeIds.removeAll(favoredNodeIds);
     }
 
+    @Override
+    public void prepare(ExecutorDetails exec) {
+        this.exec = exec;
+    }
+
     /**
-     * Scheduling uses {@link #sortAllNodes(ExecutorDetails)} which eventually
+     * Scheduling uses {@link #sortAllNodes()} which eventually
      * calls this method whose behavior can altered by setting {@link #nodeSortType}.

Review comment:
       nit : can be altered

##########
File path: storm-server/src/test/java/org/apache/storm/scheduler/resource/strategies/scheduling/sorter/TestNodeSorterHostProximity.java
##########
@@ -0,0 +1,1054 @@
+/*
+ * 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
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.storm.scheduler.resource.strategies.scheduling.sorter;
+
+import org.apache.logging.log4j.Level;
+import org.apache.logging.log4j.core.config.Configurator;
+import org.apache.storm.Config;
+import org.apache.storm.metric.StormMetricsRegistry;
+import org.apache.storm.networktopography.DNSToSwitchMapping;
+import org.apache.storm.scheduler.Cluster;
+import org.apache.storm.scheduler.ExecutorDetails;
+import org.apache.storm.scheduler.INimbus;
+import org.apache.storm.scheduler.IScheduler;
+import org.apache.storm.scheduler.SchedulerAssignment;
+import org.apache.storm.scheduler.SupervisorDetails;
+import org.apache.storm.scheduler.Topologies;
+import org.apache.storm.scheduler.TopologyDetails;
+import org.apache.storm.scheduler.WorkerSlot;
+import org.apache.storm.scheduler.resource.RasNodes;
+import org.apache.storm.scheduler.resource.ResourceAwareScheduler;
+import org.apache.storm.scheduler.resource.TestUtilsForResourceAwareScheduler;
+import org.apache.storm.scheduler.resource.normalization.NormalizedResourceRequest;
+import org.apache.storm.scheduler.resource.normalization.NormalizedResourcesExtension;
+import org.apache.storm.scheduler.resource.normalization.ResourceMetrics;
+import org.apache.storm.scheduler.resource.strategies.scheduling.BaseResourceAwareStrategy;
+import org.apache.storm.scheduler.resource.strategies.scheduling.DefaultResourceAwareStrategy;
+import org.apache.storm.scheduler.resource.strategies.scheduling.GenericResourceAwareStrategy;
+import org.apache.storm.scheduler.resource.strategies.scheduling.ObjectResourcesItem;
+import org.apache.storm.topology.TopologyBuilder;
+import org.junit.Assert;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeMap;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.stream.Collectors;
+import java.util.stream.StreamSupport;
+
+import static org.apache.storm.scheduler.resource.TestUtilsForResourceAwareScheduler.*;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+@ExtendWith({NormalizedResourcesExtension.class})
+public class TestNodeSorterHostProximity {
+    private static final Logger LOG = LoggerFactory.getLogger(TestNodeSorterHostProximity.class);
+    private static final int CURRENT_TIME = 1450418597;
+
+    protected Class getDefaultResourceAwareStrategyClass() {
+        return DefaultResourceAwareStrategy.class;
+    }
+
+    private Config createClusterConfig(double compPcore, double compOnHeap, double compOffHeap,
+                                       Map<String, Map<String, Number>> pools) {
+        Config config = TestUtilsForResourceAwareScheduler.createClusterConfig(compPcore, compOnHeap, compOffHeap, pools);
+        config.put(Config.TOPOLOGY_SCHEDULER_STRATEGY, getDefaultResourceAwareStrategyClass().getName());
+        return config;
+    }
+
+    private static class TestDNSToSwitchMapping implements DNSToSwitchMapping {
+        private final Map<String, String> hostToRackMap;
+        private final Map<String, List<String>> rackToHosts;
+
+        @SafeVarargs
+        public TestDNSToSwitchMapping(Map<String, SupervisorDetails>... racks) {
+            Set<String> seenHosts = new HashSet<>();
+            Map<String, String> hostToRackMap = new HashMap<>();
+            Map<String, List<String>> rackToHosts = new HashMap<>();
+            for (int rackNum = 0; rackNum < racks.length; rackNum++) {
+                String rack = String.format("rack-%03d", rackNum);
+                for (SupervisorDetails sup : racks[rackNum].values()) {
+                    hostToRackMap.put(sup.getHost(), rack);
+                    String host = sup.getHost();
+                    if (!seenHosts.contains(host)) {
+                        rackToHosts.computeIfAbsent(rack, rid -> new ArrayList<>()).add(host);
+                        seenHosts.add(host);
+                    }
+                }
+            }
+            this.hostToRackMap = Collections.unmodifiableMap(hostToRackMap);
+            this.rackToHosts = Collections.unmodifiableMap(rackToHosts);
+        }
+
+        /**
+         * Use the "rack-%03d" embedded in the name of the supervisor to determine the rack number.
+         *
+         * @param supervisorDetailsCollection
+         */
+        public TestDNSToSwitchMapping(Collection<SupervisorDetails> supervisorDetailsCollection) {
+            Set<String> seenHosts = new HashSet<>();
+            Map<String, String> hostToRackMap = new HashMap<>();
+            Map<String, List<String>> rackToHosts = new HashMap<>();
+
+            for (SupervisorDetails supervisorDetails: supervisorDetailsCollection) {
+                String rackId = supervisorIdToRackName(supervisorDetails.getId());
+                hostToRackMap.put(supervisorDetails.getHost(), rackId);
+                String host = supervisorDetails.getHost();
+                if (!seenHosts.contains(host)) {
+                    rackToHosts.computeIfAbsent(rackId, rid -> new ArrayList<>()).add(host);
+                    seenHosts.add(host);
+                }
+            }
+            this.hostToRackMap = Collections.unmodifiableMap(hostToRackMap);
+            this.rackToHosts = Collections.unmodifiableMap(rackToHosts);
+        }
+
+        @Override
+        public Map<String, String> resolve(List<String> names) {
+            return hostToRackMap;
+        }
+
+        public Map<String, List<String>> getRackToHosts() {
+            return rackToHosts;
+        }
+    }
+
+    /**
+     * Test whether strategy will choose correct rack.
+     */
+    @Test
+    public void testMultipleRacks() {
+        final Map<String, SupervisorDetails> supMap = new HashMap<>();
+        final int numRacks = 1;
+        final int numSupersPerRack = 10;
+        final int numPortsPerSuper = 4;
+        final int numZonesPerHost = 1;
+        final double numaResourceMultiplier = 1.0;
+        int rackStartNum = 0;
+        int supStartNum = 0;
+
+        final Map<String, SupervisorDetails> supMapRack0 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400, 8000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate another rack of supervisors with less resources
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack1 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                200, 4000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate some supervisors that are depleted of one resource
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack2 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                0, 8000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate some that has a lot of memory but little of cpu
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack3 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                10, 8000 * 2 + 4000, Collections.emptyMap(),numaResourceMultiplier);
+
+        //generate some that has a lot of cpu but little of memory
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack4 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400 + 200 + 10, 1000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //Generate some that have neither resource, to verify that the strategy will prioritize this last
+        //Also put a generic resource with 0 value in the resources list, to verify that it doesn't affect the sorting
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack5 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                0.0, 0.0, Collections.singletonMap("gpu.count", 0.0), numaResourceMultiplier);
+
+        supMap.putAll(supMapRack0);
+        supMap.putAll(supMapRack1);
+        supMap.putAll(supMapRack2);
+        supMap.putAll(supMapRack3);
+        supMap.putAll(supMapRack4);
+        supMap.putAll(supMapRack5);
+
+        Config config = createClusterConfig(100, 500, 500, null);
+        config.put(Config.TOPOLOGY_WORKER_MAX_HEAP_SIZE_MB, Double.MAX_VALUE);
+        INimbus iNimbus = new INimbusTest();
+
+        //create test DNSToSwitchMapping plugin
+        TestDNSToSwitchMapping testDNSToSwitchMapping =
+                new TestDNSToSwitchMapping(supMapRack0, supMapRack1, supMapRack2, supMapRack3, supMapRack4, supMapRack5);
+
+        //generate topologies
+        TopologyDetails topo1 = genTopology("topo-1", config, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+        TopologyDetails topo2 = genTopology("topo-2", config, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+        Topologies topologies = new Topologies(topo1, topo2);
+        Cluster cluster = new Cluster(iNimbus, new ResourceMetrics(new StormMetricsRegistry()), supMap, new HashMap<>(), topologies, config);
+
+        List<String> supHostnames = new LinkedList<>();
+        for (SupervisorDetails sup : supMap.values()) {
+            supHostnames.add(sup.getHost());
+        }
+        Map<String, List<String>> rackToHosts = testDNSToSwitchMapping.getRackToHosts();
+        cluster.setNetworkTopography(rackToHosts);
+        System.out.println("DEBUG: rackToHosts: " + rackToHosts.toString());
+
+        NodeSorterHostProximity nodeSorter = new NodeSorterHostProximity(cluster, topo1, BaseResourceAwareStrategy.NodeSortType.DEFAULT_RAS);
+        nodeSorter.prepare(null);
+        List<ObjectResourcesItem> sortedRacks = StreamSupport.stream(nodeSorter.getSortedRacks().spliterator(), false)
+                .collect(Collectors.toList());
+        String rackSummaries = sortedRacks.stream()
+                .map(x -> String.format("Rack %s -> scheduled-cnt %d, min-avail %f, avg-avail %f, cpu %f, mem %f",
+                        x.id, nodeSorter.getScheduledExecCntByRackId().getOrDefault(x.id, new AtomicInteger(-1)).get(),
+                        x.minResourcePercent, x.avgResourcePercent,
+                        x.availableResources.getTotalCpu(),
+                        x.availableResources.getTotalMemoryMb()))
+                .collect(Collectors.joining("\n\t"));
+        Assert.assertEquals(rackSummaries + "\n# of racks sorted", 6, sortedRacks.size());
+        Iterator<ObjectResourcesItem> it = sortedRacks.iterator();
+        Assert.assertEquals(rackSummaries + "\nrack-000 should be ordered first since it has the most balanced set of resources", "rack-000", it.next().id);
+        Assert.assertEquals(rackSummaries + "\nrack-001 should be ordered second since it has a balanced set of resources but less than rack-000", "rack-001", it.next().id);
+        Assert.assertEquals(rackSummaries + "\nrack-004 should be ordered third since it has a lot of cpu but not a lot of memory", "rack-004", it.next().id);
+        Assert.assertEquals(rackSummaries + "\nrack-003 should be ordered fourth since it has a lot of memory but not cpu", "rack-003", it.next().id);
+        Assert.assertEquals(rackSummaries + "\nrack-002 should be ordered fifth since it has not cpu resources", "rack-002", it.next().id);
+        Assert.assertEquals(rackSummaries + "\nRack-005 should be ordered sixth since it has neither CPU nor memory available", "rack-005", it.next().id);
+    }
+
+    /**
+     * Test whether strategy will choose correct rack.
+     */
+    @Test
+    public void testMultipleRacksWithFavoritism() {
+        final Map<String, SupervisorDetails> supMap = new HashMap<>();
+        final int numRacks = 1;
+        final int numSupersPerRack = 10;
+        final int numPortsPerSuper = 4;
+        final int numZonesPerHost = 2;
+        int rackStartNum = 0;
+        int supStartNum = 0;
+        final Map<String, SupervisorDetails> supMapRack0 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400, 8000, Collections.emptyMap(), 1.0);
+
+        //generate another rack of supervisors with less resources
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack1 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                200, 4000, Collections.emptyMap(), 1.0);
+
+        //generate some supervisors that are depleted of one resource
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack2 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                0, 8000, Collections.emptyMap(), 1.0);
+
+        //generate some that has a lot of memory but little of cpu
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack3 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                10, 8000 * 2 + 4000, Collections.emptyMap(), 1.0);
+
+        //generate some that has a lot of cpu but little of memory
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack4 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400 + 200 + 10, 1000, Collections.emptyMap(), 1.0);
+
+        supMap.putAll(supMapRack0);
+        supMap.putAll(supMapRack1);
+        supMap.putAll(supMapRack2);
+        supMap.putAll(supMapRack3);
+        supMap.putAll(supMapRack4);
+
+        Config config = createClusterConfig(100, 500, 500, null);
+        config.put(Config.TOPOLOGY_WORKER_MAX_HEAP_SIZE_MB, Double.MAX_VALUE);
+        INimbus iNimbus = new INimbusTest();
+
+        //create test DNSToSwitchMapping plugin
+        TestDNSToSwitchMapping testDNSToSwitchMapping =
+                new TestDNSToSwitchMapping(supMapRack0, supMapRack1, supMapRack2, supMapRack3, supMapRack4);
+
+        Config t1Conf = new Config();
+        t1Conf.putAll(config);
+        final List<String> t1FavoredHostNames = Arrays.asList("host-41", "host-42", "host-43");
+        t1Conf.put(Config.TOPOLOGY_SCHEDULER_FAVORED_NODES, t1FavoredHostNames);
+        final List<String> t1UnfavoredHostIds = Arrays.asList("host-1", "host-2", "host-3");
+        t1Conf.put(Config.TOPOLOGY_SCHEDULER_UNFAVORED_NODES, t1UnfavoredHostIds);
+        //generate topologies
+        TopologyDetails topo1 = genTopology("topo-1", t1Conf, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+
+        Config t2Conf = new Config();
+        t2Conf.putAll(config);
+        t2Conf.put(Config.TOPOLOGY_SCHEDULER_FAVORED_NODES, Arrays.asList("host-31", "host-32", "host-33"));
+        t2Conf.put(Config.TOPOLOGY_SCHEDULER_UNFAVORED_NODES, Arrays.asList("host-11", "host-12", "host-13"));
+        TopologyDetails topo2 = genTopology("topo-2", t2Conf, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+        Topologies topologies = new Topologies(topo1, topo2);
+        Cluster cluster = new Cluster(iNimbus, new ResourceMetrics(new StormMetricsRegistry()), supMap, new HashMap<>(), topologies, config);
+
+        List<String> supHostnames = new LinkedList<>();
+        for (SupervisorDetails sup : supMap.values()) {
+            supHostnames.add(sup.getHost());
+        }
+        Map<String, List<String>> rackToHosts = testDNSToSwitchMapping.getRackToHosts();
+        cluster.setNetworkTopography(rackToHosts);
+
+        NodeSorterHostProximity nodeSorter = new NodeSorterHostProximity(cluster, topo1, BaseResourceAwareStrategy.NodeSortType.DEFAULT_RAS);
+        nodeSorter.prepare(null);
+        List<ObjectResourcesItem> sortedRacks = StreamSupport.stream(nodeSorter.getSortedRacks().spliterator(), false)
+                .collect(Collectors.toList());
+        String rackSummaries = sortedRacks.stream()
+                .map(x -> String.format("Rack %s -> scheduled-cnt %d, min-avail %f, avg-avail %f, cpu %f, mem %f",
+                        x.id, nodeSorter.getScheduledExecCntByRackId().getOrDefault(x.id, new AtomicInteger(-1)).get(),
+                        x.minResourcePercent, x.avgResourcePercent,
+                        x.availableResources.getTotalCpu(),
+                        x.availableResources.getTotalMemoryMb()))
+                .collect(Collectors.joining("\n\t"));
+
+        Iterator<ObjectResourcesItem> it = sortedRacks.iterator();
+        // Ranked first since rack-000 has the most balanced set of resources
+        Assert.assertEquals("rack-000 should be ordered first", "rack-000", it.next().id);
+        // Ranked second since rack-1 has a balanced set of resources but less than rack-0
+        Assert.assertEquals("rack-001 should be ordered second", "rack-001", it.next().id);
+        // Ranked third since rack-4 has a lot of cpu but not a lot of memory
+        Assert.assertEquals("rack-004 should be ordered third", "rack-004", it.next().id);
+        // Ranked fourth since rack-3 has alot of memory but not cpu
+        Assert.assertEquals("rack-003 should be ordered fourth", "rack-003", it.next().id);
+        //Ranked last since rack-2 has not cpu resources
+        Assert.assertEquals("rack-00s2 should be ordered fifth", "rack-002", it.next().id);
+    }
+
+    /**
+     * Test if hosts are presented together regardless of resource availability.
+     * Supervisors are created with multiple Numa zones in such a manner that resources on two numa zones on the same host
+     * differ widely in resource availability.
+     */
+    @Test
+    public void testMultipleRacksWithHostProximity() {
+        final Map<String, SupervisorDetails> supMap = new HashMap<>();
+        final int numRacks = 1;
+        final int numSupersPerRack = 12;
+        final int numPortsPerSuper = 4;
+        final int numZonesPerHost = 3;
+        final double numaResourceMultiplier = 0.4;
+        int rackStartNum = 0;
+        int supStartNum = 0;
+
+        final Map<String, SupervisorDetails> supMapRack0 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400, 8000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate another rack of supervisors with less resources
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack1 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                200, 4000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate some supervisors that are depleted of one resource
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack2 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                0, 8000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate some that has a lot of memory but little of cpu
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack3 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                10, 8000 * 2 + 4000, Collections.emptyMap(),numaResourceMultiplier);
+
+        //generate some that has a lot of cpu but little of memory
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack4 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400 + 200 + 10, 1000, Collections.emptyMap(), numaResourceMultiplier);
+
+        supMap.putAll(supMapRack0);
+        supMap.putAll(supMapRack1);
+        supMap.putAll(supMapRack2);
+        supMap.putAll(supMapRack3);
+        supMap.putAll(supMapRack4);
+
+        Config config = createClusterConfig(100, 500, 500, null);
+        config.put(Config.TOPOLOGY_WORKER_MAX_HEAP_SIZE_MB, Double.MAX_VALUE);
+        INimbus iNimbus = new INimbusTest();
+
+        //create test DNSToSwitchMapping plugin
+        TestDNSToSwitchMapping testDNSToSwitchMapping =
+                new TestDNSToSwitchMapping(supMapRack0, supMapRack1, supMapRack2, supMapRack3, supMapRack4);
+
+        Config t1Conf = new Config();
+        t1Conf.putAll(config);
+        final List<String> t1FavoredHostNames = Arrays.asList("host-41", "host-42", "host-43");
+        t1Conf.put(Config.TOPOLOGY_SCHEDULER_FAVORED_NODES, t1FavoredHostNames);
+        final List<String> t1UnfavoredHostIds = Arrays.asList("host-1", "host-2", "host-3");
+        t1Conf.put(Config.TOPOLOGY_SCHEDULER_UNFAVORED_NODES, t1UnfavoredHostIds);
+        //generate topologies
+        TopologyDetails topo1 = genTopology("topo-1", t1Conf, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+
+        Config t2Conf = new Config();
+        t2Conf.putAll(config);
+        t2Conf.put(Config.TOPOLOGY_SCHEDULER_FAVORED_NODES, Arrays.asList("host-31", "host-32", "host-33"));
+        t2Conf.put(Config.TOPOLOGY_SCHEDULER_UNFAVORED_NODES, Arrays.asList("host-11", "host-12", "host-13"));
+        TopologyDetails topo2 = genTopology("topo-2", t2Conf, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+        Topologies topologies = new Topologies(topo1, topo2);
+        Cluster cluster = new Cluster(iNimbus, new ResourceMetrics(new StormMetricsRegistry()), supMap, new HashMap<>(), topologies, config);
+
+        cluster.setNetworkTopography(testDNSToSwitchMapping.getRackToHosts());
+
+        INodeSorter nodeSorter = new NodeSorterHostProximity(cluster, topo1);
+        nodeSorter.prepare(null);
+
+        Set<String> seenHosts = new HashSet<>();
+        String prevHost = null;
+        List<String> errLines = new ArrayList();
+        Map<String, String> nodeToHost = new RasNodes(cluster).getNodeIdToHostname();
+        for (String nodeId: nodeSorter.sortAllNodes()) {
+            String host = nodeToHost.getOrDefault(nodeId, "no-host-for-node-" + nodeId);
+            errLines.add(String.format("\tnodeId:%s, host:%s", nodeId, host));
+            if (!host.equals(prevHost) && seenHosts.contains(host)) {
+                String err = String.format("Host %s for node %s is out of order:\n\t%s", host, nodeId, String.join("\n\t", errLines));
+                Assert.fail(err);
+            }
+            seenHosts.add(host);
+            prevHost = host;
+        }
+        System.out.printf("DEBUG: Test Success: Hosts are listed together:\n\t%s\n", String.join("\n\t", errLines));
+    }
+
+    /**
+     * Racks should be returned in order of decreasing capacity.
+     */
+    @Test
+    public void testMultipleRacksOrderedByCapacity() {
+        final Map<String, SupervisorDetails> supMap = new HashMap<>();
+        final int numRacks = 1;
+        final int numSupersPerRack = 10;
+        final int numPortsPerSuper = 4;
+        final int numZonesPerHost = 1;
+        final double numaResourceMultiplier = 1.0;
+        int rackStartNum = 0;
+        int supStartNum = 0;
+
+        final Map<String, SupervisorDetails> supMapRack0 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                600, 8000 - rackStartNum, Collections.emptyMap(), numaResourceMultiplier);
+
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack1 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                500, 8000 - rackStartNum, Collections.emptyMap(), numaResourceMultiplier);
+
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack2 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400, 8000 - rackStartNum, Collections.emptyMap(), numaResourceMultiplier);
+
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack3 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                300, 8000 - rackStartNum, Collections.emptyMap(),numaResourceMultiplier);
+
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack4 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                200, 8000 - rackStartNum, Collections.emptyMap(), numaResourceMultiplier);
+
+        // too small to hold topology
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack5 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                100, 8000 - rackStartNum, Collections.singletonMap("gpu.count", 0.0), numaResourceMultiplier);
+
+        supMap.putAll(supMapRack0);
+        supMap.putAll(supMapRack1);
+        supMap.putAll(supMapRack2);
+        supMap.putAll(supMapRack3);
+        supMap.putAll(supMapRack4);
+        supMap.putAll(supMapRack5);
+
+        Config config = createClusterConfig(100, 500, 500, null);
+        config.put(Config.TOPOLOGY_WORKER_MAX_HEAP_SIZE_MB, Double.MAX_VALUE);
+        INimbus iNimbus = new INimbusTest();
+
+        //create test DNSToSwitchMapping plugin
+        TestDNSToSwitchMapping testDNSToSwitchMapping =
+                new TestDNSToSwitchMapping(supMapRack0, supMapRack1, supMapRack2, supMapRack3, supMapRack4, supMapRack5);
+
+        //generate topologies
+        TopologyDetails topo1 = genTopology("topo-1", config, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+        TopologyDetails topo2 = genTopology("topo-2", config, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+        Topologies topologies = new Topologies(topo1, topo2);
+        Cluster cluster = new Cluster(iNimbus, new ResourceMetrics(new StormMetricsRegistry()), supMap, new HashMap<>(), topologies, config);
+
+        cluster.setNetworkTopography(testDNSToSwitchMapping.getRackToHosts());
+
+        NodeSorterHostProximity nodeSorter = new NodeSorterHostProximity(cluster, topo1);
+        nodeSorter.prepare(null);
+        List<ObjectResourcesItem> sortedRacks = StreamSupport.stream(nodeSorter.getSortedRacks().spliterator(), false)
+                .collect(Collectors.toList());
+        String rackSummaries = sortedRacks
+                .stream()
+                .map(x -> String.format("Rack %s -> scheduled-cnt %d, min-avail %f, avg-avail %f, cpu %f, mem %f",
+                        x.id, nodeSorter.getScheduledExecCntByRackId().getOrDefault(x.id, new AtomicInteger(-1)).get(),
+                        x.minResourcePercent, x.avgResourcePercent,
+                        x.availableResources.getTotalCpu(),
+                        x.availableResources.getTotalMemoryMb()))
+                .collect(Collectors.joining("\n\t"));
+        NormalizedResourceRequest topoResourceRequest = topo1.getApproximateTotalResources();
+        String topoRequest = String.format("Topo %s, approx-requested-resources %s", topo1.getId(), topoResourceRequest.toString());
+        //Assert.assertEquals(rackSummaries + "\n# of racks sorted", 6, sortedRacks.size());
+        Iterator<ObjectResourcesItem> it = sortedRacks.iterator();
+        Assert.assertEquals(topoRequest + "\n\t" + rackSummaries + "\nRack-000 should be ordered first since it has the largest capacity", "rack-000", it.next().id);
+        Assert.assertEquals(topoRequest + "\n\t" + rackSummaries + "\nrack-001 should be ordered second since it smaller than rack-000", "rack-001", it.next().id);
+        Assert.assertEquals(topoRequest + "\n\t" + rackSummaries + "\nrack-002 should be ordered third since it is smaller than rack-001", "rack-002", it.next().id);
+        Assert.assertEquals(topoRequest + "\n\t" + rackSummaries + "\nrack-003 should be ordered fourth since it since it is smaller than rack-002", "rack-003", it.next().id);
+        Assert.assertEquals(topoRequest + "\n\t" + rackSummaries + "\nrack-004 should be ordered fifth since it since it is smaller than rack-003", "rack-004", it.next().id);
+        Assert.assertEquals(topoRequest + "\n\t" + rackSummaries + "\nrack-005 should be ordered last since it since it is has smallest capacity", "rack-005", it.next().id);
+    }
+
+    /**
+     * Schedule two topologies, once with special resources and another without.
+     * There are enough special resources to hold one topology with special resource ("my.gpu").
+     * If the sort order is incorrect, scheduling will not succeed.
+     */
+    @Test
+    public void testAntiAffinityWithMultipleTopologies() {
+        INimbus iNimbus = new INimbusTest();
+        Map<String, SupervisorDetails> supMap = genSupervisorsWithRacks(1, 40, 66, 0, 0, 4700, 226200, new HashMap<>());
+        HashMap<String, Double> extraResources = new HashMap<>();
+        extraResources.put("my.gpu", 1.0);
+        supMap.putAll(genSupervisorsWithRacks(1, 40, 66, 1, 0, 4700, 226200, extraResources));
+
+        Config config = new Config();
+        config.putAll(createGrasClusterConfig(88, 775, 25, null, null));
+        //config.put(Config.TOPOLOGY_SCHEDULER_STRATEGY, GenericResourceAwareStrategy.class.getName());

Review comment:
       Remove unused code; or uncomment it if it is used

##########
File path: storm-server/src/test/java/org/apache/storm/scheduler/resource/strategies/scheduling/sorter/TestNodeSorterHostProximity.java
##########
@@ -0,0 +1,1054 @@
+/*
+ * 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
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.storm.scheduler.resource.strategies.scheduling.sorter;
+
+import org.apache.logging.log4j.Level;
+import org.apache.logging.log4j.core.config.Configurator;
+import org.apache.storm.Config;
+import org.apache.storm.metric.StormMetricsRegistry;
+import org.apache.storm.networktopography.DNSToSwitchMapping;
+import org.apache.storm.scheduler.Cluster;
+import org.apache.storm.scheduler.ExecutorDetails;
+import org.apache.storm.scheduler.INimbus;
+import org.apache.storm.scheduler.IScheduler;
+import org.apache.storm.scheduler.SchedulerAssignment;
+import org.apache.storm.scheduler.SupervisorDetails;
+import org.apache.storm.scheduler.Topologies;
+import org.apache.storm.scheduler.TopologyDetails;
+import org.apache.storm.scheduler.WorkerSlot;
+import org.apache.storm.scheduler.resource.RasNodes;
+import org.apache.storm.scheduler.resource.ResourceAwareScheduler;
+import org.apache.storm.scheduler.resource.TestUtilsForResourceAwareScheduler;
+import org.apache.storm.scheduler.resource.normalization.NormalizedResourceRequest;
+import org.apache.storm.scheduler.resource.normalization.NormalizedResourcesExtension;
+import org.apache.storm.scheduler.resource.normalization.ResourceMetrics;
+import org.apache.storm.scheduler.resource.strategies.scheduling.BaseResourceAwareStrategy;
+import org.apache.storm.scheduler.resource.strategies.scheduling.DefaultResourceAwareStrategy;
+import org.apache.storm.scheduler.resource.strategies.scheduling.GenericResourceAwareStrategy;
+import org.apache.storm.scheduler.resource.strategies.scheduling.ObjectResourcesItem;
+import org.apache.storm.topology.TopologyBuilder;
+import org.junit.Assert;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeMap;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.stream.Collectors;
+import java.util.stream.StreamSupport;
+
+import static org.apache.storm.scheduler.resource.TestUtilsForResourceAwareScheduler.*;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+@ExtendWith({NormalizedResourcesExtension.class})
+public class TestNodeSorterHostProximity {
+    private static final Logger LOG = LoggerFactory.getLogger(TestNodeSorterHostProximity.class);
+    private static final int CURRENT_TIME = 1450418597;
+
+    protected Class getDefaultResourceAwareStrategyClass() {
+        return DefaultResourceAwareStrategy.class;
+    }
+
+    private Config createClusterConfig(double compPcore, double compOnHeap, double compOffHeap,
+                                       Map<String, Map<String, Number>> pools) {
+        Config config = TestUtilsForResourceAwareScheduler.createClusterConfig(compPcore, compOnHeap, compOffHeap, pools);
+        config.put(Config.TOPOLOGY_SCHEDULER_STRATEGY, getDefaultResourceAwareStrategyClass().getName());
+        return config;
+    }
+
+    private static class TestDNSToSwitchMapping implements DNSToSwitchMapping {
+        private final Map<String, String> hostToRackMap;
+        private final Map<String, List<String>> rackToHosts;
+
+        @SafeVarargs
+        public TestDNSToSwitchMapping(Map<String, SupervisorDetails>... racks) {
+            Set<String> seenHosts = new HashSet<>();
+            Map<String, String> hostToRackMap = new HashMap<>();
+            Map<String, List<String>> rackToHosts = new HashMap<>();
+            for (int rackNum = 0; rackNum < racks.length; rackNum++) {
+                String rack = String.format("rack-%03d", rackNum);
+                for (SupervisorDetails sup : racks[rackNum].values()) {
+                    hostToRackMap.put(sup.getHost(), rack);
+                    String host = sup.getHost();
+                    if (!seenHosts.contains(host)) {
+                        rackToHosts.computeIfAbsent(rack, rid -> new ArrayList<>()).add(host);
+                        seenHosts.add(host);
+                    }
+                }
+            }
+            this.hostToRackMap = Collections.unmodifiableMap(hostToRackMap);
+            this.rackToHosts = Collections.unmodifiableMap(rackToHosts);
+        }
+
+        /**
+         * Use the "rack-%03d" embedded in the name of the supervisor to determine the rack number.
+         *
+         * @param supervisorDetailsCollection
+         */
+        public TestDNSToSwitchMapping(Collection<SupervisorDetails> supervisorDetailsCollection) {
+            Set<String> seenHosts = new HashSet<>();
+            Map<String, String> hostToRackMap = new HashMap<>();
+            Map<String, List<String>> rackToHosts = new HashMap<>();
+
+            for (SupervisorDetails supervisorDetails: supervisorDetailsCollection) {
+                String rackId = supervisorIdToRackName(supervisorDetails.getId());
+                hostToRackMap.put(supervisorDetails.getHost(), rackId);
+                String host = supervisorDetails.getHost();
+                if (!seenHosts.contains(host)) {
+                    rackToHosts.computeIfAbsent(rackId, rid -> new ArrayList<>()).add(host);
+                    seenHosts.add(host);
+                }
+            }
+            this.hostToRackMap = Collections.unmodifiableMap(hostToRackMap);
+            this.rackToHosts = Collections.unmodifiableMap(rackToHosts);
+        }
+
+        @Override
+        public Map<String, String> resolve(List<String> names) {
+            return hostToRackMap;
+        }
+
+        public Map<String, List<String>> getRackToHosts() {
+            return rackToHosts;
+        }
+    }
+
+    /**
+     * Test whether strategy will choose correct rack.
+     */
+    @Test
+    public void testMultipleRacks() {
+        final Map<String, SupervisorDetails> supMap = new HashMap<>();
+        final int numRacks = 1;
+        final int numSupersPerRack = 10;
+        final int numPortsPerSuper = 4;
+        final int numZonesPerHost = 1;
+        final double numaResourceMultiplier = 1.0;
+        int rackStartNum = 0;
+        int supStartNum = 0;
+
+        final Map<String, SupervisorDetails> supMapRack0 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400, 8000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate another rack of supervisors with less resources
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack1 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                200, 4000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate some supervisors that are depleted of one resource
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack2 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                0, 8000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate some that has a lot of memory but little of cpu
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack3 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                10, 8000 * 2 + 4000, Collections.emptyMap(),numaResourceMultiplier);
+
+        //generate some that has a lot of cpu but little of memory
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack4 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400 + 200 + 10, 1000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //Generate some that have neither resource, to verify that the strategy will prioritize this last
+        //Also put a generic resource with 0 value in the resources list, to verify that it doesn't affect the sorting
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack5 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                0.0, 0.0, Collections.singletonMap("gpu.count", 0.0), numaResourceMultiplier);
+
+        supMap.putAll(supMapRack0);
+        supMap.putAll(supMapRack1);
+        supMap.putAll(supMapRack2);
+        supMap.putAll(supMapRack3);
+        supMap.putAll(supMapRack4);
+        supMap.putAll(supMapRack5);
+
+        Config config = createClusterConfig(100, 500, 500, null);
+        config.put(Config.TOPOLOGY_WORKER_MAX_HEAP_SIZE_MB, Double.MAX_VALUE);
+        INimbus iNimbus = new INimbusTest();
+
+        //create test DNSToSwitchMapping plugin
+        TestDNSToSwitchMapping testDNSToSwitchMapping =
+                new TestDNSToSwitchMapping(supMapRack0, supMapRack1, supMapRack2, supMapRack3, supMapRack4, supMapRack5);
+
+        //generate topologies
+        TopologyDetails topo1 = genTopology("topo-1", config, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+        TopologyDetails topo2 = genTopology("topo-2", config, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+        Topologies topologies = new Topologies(topo1, topo2);
+        Cluster cluster = new Cluster(iNimbus, new ResourceMetrics(new StormMetricsRegistry()), supMap, new HashMap<>(), topologies, config);
+
+        List<String> supHostnames = new LinkedList<>();
+        for (SupervisorDetails sup : supMap.values()) {
+            supHostnames.add(sup.getHost());
+        }
+        Map<String, List<String>> rackToHosts = testDNSToSwitchMapping.getRackToHosts();
+        cluster.setNetworkTopography(rackToHosts);
+        System.out.println("DEBUG: rackToHosts: " + rackToHosts.toString());

Review comment:
       Should we use `LOG.info` here?

##########
File path: storm-server/src/test/java/org/apache/storm/scheduler/resource/strategies/scheduling/sorter/TestNodeSorterHostProximity.java
##########
@@ -0,0 +1,1054 @@
+/*
+ * 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
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.storm.scheduler.resource.strategies.scheduling.sorter;
+
+import org.apache.logging.log4j.Level;
+import org.apache.logging.log4j.core.config.Configurator;
+import org.apache.storm.Config;
+import org.apache.storm.metric.StormMetricsRegistry;
+import org.apache.storm.networktopography.DNSToSwitchMapping;
+import org.apache.storm.scheduler.Cluster;
+import org.apache.storm.scheduler.ExecutorDetails;
+import org.apache.storm.scheduler.INimbus;
+import org.apache.storm.scheduler.IScheduler;
+import org.apache.storm.scheduler.SchedulerAssignment;
+import org.apache.storm.scheduler.SupervisorDetails;
+import org.apache.storm.scheduler.Topologies;
+import org.apache.storm.scheduler.TopologyDetails;
+import org.apache.storm.scheduler.WorkerSlot;
+import org.apache.storm.scheduler.resource.RasNodes;
+import org.apache.storm.scheduler.resource.ResourceAwareScheduler;
+import org.apache.storm.scheduler.resource.TestUtilsForResourceAwareScheduler;
+import org.apache.storm.scheduler.resource.normalization.NormalizedResourceRequest;
+import org.apache.storm.scheduler.resource.normalization.NormalizedResourcesExtension;
+import org.apache.storm.scheduler.resource.normalization.ResourceMetrics;
+import org.apache.storm.scheduler.resource.strategies.scheduling.BaseResourceAwareStrategy;
+import org.apache.storm.scheduler.resource.strategies.scheduling.DefaultResourceAwareStrategy;
+import org.apache.storm.scheduler.resource.strategies.scheduling.GenericResourceAwareStrategy;
+import org.apache.storm.scheduler.resource.strategies.scheduling.ObjectResourcesItem;
+import org.apache.storm.topology.TopologyBuilder;
+import org.junit.Assert;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeMap;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.stream.Collectors;
+import java.util.stream.StreamSupport;
+
+import static org.apache.storm.scheduler.resource.TestUtilsForResourceAwareScheduler.*;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+@ExtendWith({NormalizedResourcesExtension.class})
+public class TestNodeSorterHostProximity {
+    private static final Logger LOG = LoggerFactory.getLogger(TestNodeSorterHostProximity.class);
+    private static final int CURRENT_TIME = 1450418597;
+
+    protected Class getDefaultResourceAwareStrategyClass() {
+        return DefaultResourceAwareStrategy.class;
+    }
+
+    private Config createClusterConfig(double compPcore, double compOnHeap, double compOffHeap,
+                                       Map<String, Map<String, Number>> pools) {
+        Config config = TestUtilsForResourceAwareScheduler.createClusterConfig(compPcore, compOnHeap, compOffHeap, pools);
+        config.put(Config.TOPOLOGY_SCHEDULER_STRATEGY, getDefaultResourceAwareStrategyClass().getName());
+        return config;
+    }
+
+    private static class TestDNSToSwitchMapping implements DNSToSwitchMapping {
+        private final Map<String, String> hostToRackMap;
+        private final Map<String, List<String>> rackToHosts;
+
+        @SafeVarargs
+        public TestDNSToSwitchMapping(Map<String, SupervisorDetails>... racks) {
+            Set<String> seenHosts = new HashSet<>();
+            Map<String, String> hostToRackMap = new HashMap<>();
+            Map<String, List<String>> rackToHosts = new HashMap<>();
+            for (int rackNum = 0; rackNum < racks.length; rackNum++) {
+                String rack = String.format("rack-%03d", rackNum);
+                for (SupervisorDetails sup : racks[rackNum].values()) {
+                    hostToRackMap.put(sup.getHost(), rack);
+                    String host = sup.getHost();
+                    if (!seenHosts.contains(host)) {
+                        rackToHosts.computeIfAbsent(rack, rid -> new ArrayList<>()).add(host);
+                        seenHosts.add(host);
+                    }
+                }
+            }
+            this.hostToRackMap = Collections.unmodifiableMap(hostToRackMap);
+            this.rackToHosts = Collections.unmodifiableMap(rackToHosts);
+        }
+
+        /**
+         * Use the "rack-%03d" embedded in the name of the supervisor to determine the rack number.
+         *
+         * @param supervisorDetailsCollection
+         */
+        public TestDNSToSwitchMapping(Collection<SupervisorDetails> supervisorDetailsCollection) {
+            Set<String> seenHosts = new HashSet<>();
+            Map<String, String> hostToRackMap = new HashMap<>();
+            Map<String, List<String>> rackToHosts = new HashMap<>();
+
+            for (SupervisorDetails supervisorDetails: supervisorDetailsCollection) {
+                String rackId = supervisorIdToRackName(supervisorDetails.getId());
+                hostToRackMap.put(supervisorDetails.getHost(), rackId);
+                String host = supervisorDetails.getHost();
+                if (!seenHosts.contains(host)) {
+                    rackToHosts.computeIfAbsent(rackId, rid -> new ArrayList<>()).add(host);
+                    seenHosts.add(host);
+                }
+            }
+            this.hostToRackMap = Collections.unmodifiableMap(hostToRackMap);
+            this.rackToHosts = Collections.unmodifiableMap(rackToHosts);
+        }
+
+        @Override
+        public Map<String, String> resolve(List<String> names) {
+            return hostToRackMap;
+        }
+
+        public Map<String, List<String>> getRackToHosts() {
+            return rackToHosts;
+        }
+    }
+
+    /**
+     * Test whether strategy will choose correct rack.
+     */
+    @Test
+    public void testMultipleRacks() {
+        final Map<String, SupervisorDetails> supMap = new HashMap<>();
+        final int numRacks = 1;
+        final int numSupersPerRack = 10;
+        final int numPortsPerSuper = 4;
+        final int numZonesPerHost = 1;
+        final double numaResourceMultiplier = 1.0;
+        int rackStartNum = 0;
+        int supStartNum = 0;
+
+        final Map<String, SupervisorDetails> supMapRack0 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400, 8000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate another rack of supervisors with less resources
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack1 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                200, 4000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate some supervisors that are depleted of one resource
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack2 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                0, 8000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate some that has a lot of memory but little of cpu
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack3 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                10, 8000 * 2 + 4000, Collections.emptyMap(),numaResourceMultiplier);
+
+        //generate some that has a lot of cpu but little of memory
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack4 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400 + 200 + 10, 1000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //Generate some that have neither resource, to verify that the strategy will prioritize this last
+        //Also put a generic resource with 0 value in the resources list, to verify that it doesn't affect the sorting
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack5 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                0.0, 0.0, Collections.singletonMap("gpu.count", 0.0), numaResourceMultiplier);
+
+        supMap.putAll(supMapRack0);
+        supMap.putAll(supMapRack1);
+        supMap.putAll(supMapRack2);
+        supMap.putAll(supMapRack3);
+        supMap.putAll(supMapRack4);
+        supMap.putAll(supMapRack5);
+
+        Config config = createClusterConfig(100, 500, 500, null);
+        config.put(Config.TOPOLOGY_WORKER_MAX_HEAP_SIZE_MB, Double.MAX_VALUE);
+        INimbus iNimbus = new INimbusTest();
+
+        //create test DNSToSwitchMapping plugin
+        TestDNSToSwitchMapping testDNSToSwitchMapping =
+                new TestDNSToSwitchMapping(supMapRack0, supMapRack1, supMapRack2, supMapRack3, supMapRack4, supMapRack5);
+
+        //generate topologies
+        TopologyDetails topo1 = genTopology("topo-1", config, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+        TopologyDetails topo2 = genTopology("topo-2", config, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+        Topologies topologies = new Topologies(topo1, topo2);
+        Cluster cluster = new Cluster(iNimbus, new ResourceMetrics(new StormMetricsRegistry()), supMap, new HashMap<>(), topologies, config);
+
+        List<String> supHostnames = new LinkedList<>();
+        for (SupervisorDetails sup : supMap.values()) {
+            supHostnames.add(sup.getHost());
+        }
+        Map<String, List<String>> rackToHosts = testDNSToSwitchMapping.getRackToHosts();
+        cluster.setNetworkTopography(rackToHosts);
+        System.out.println("DEBUG: rackToHosts: " + rackToHosts.toString());
+
+        NodeSorterHostProximity nodeSorter = new NodeSorterHostProximity(cluster, topo1, BaseResourceAwareStrategy.NodeSortType.DEFAULT_RAS);
+        nodeSorter.prepare(null);
+        List<ObjectResourcesItem> sortedRacks = StreamSupport.stream(nodeSorter.getSortedRacks().spliterator(), false)
+                .collect(Collectors.toList());
+        String rackSummaries = sortedRacks.stream()
+                .map(x -> String.format("Rack %s -> scheduled-cnt %d, min-avail %f, avg-avail %f, cpu %f, mem %f",
+                        x.id, nodeSorter.getScheduledExecCntByRackId().getOrDefault(x.id, new AtomicInteger(-1)).get(),
+                        x.minResourcePercent, x.avgResourcePercent,
+                        x.availableResources.getTotalCpu(),
+                        x.availableResources.getTotalMemoryMb()))
+                .collect(Collectors.joining("\n\t"));
+        Assert.assertEquals(rackSummaries + "\n# of racks sorted", 6, sortedRacks.size());
+        Iterator<ObjectResourcesItem> it = sortedRacks.iterator();
+        Assert.assertEquals(rackSummaries + "\nrack-000 should be ordered first since it has the most balanced set of resources", "rack-000", it.next().id);
+        Assert.assertEquals(rackSummaries + "\nrack-001 should be ordered second since it has a balanced set of resources but less than rack-000", "rack-001", it.next().id);
+        Assert.assertEquals(rackSummaries + "\nrack-004 should be ordered third since it has a lot of cpu but not a lot of memory", "rack-004", it.next().id);
+        Assert.assertEquals(rackSummaries + "\nrack-003 should be ordered fourth since it has a lot of memory but not cpu", "rack-003", it.next().id);
+        Assert.assertEquals(rackSummaries + "\nrack-002 should be ordered fifth since it has not cpu resources", "rack-002", it.next().id);
+        Assert.assertEquals(rackSummaries + "\nRack-005 should be ordered sixth since it has neither CPU nor memory available", "rack-005", it.next().id);
+    }
+
+    /**
+     * Test whether strategy will choose correct rack.
+     */
+    @Test
+    public void testMultipleRacksWithFavoritism() {
+        final Map<String, SupervisorDetails> supMap = new HashMap<>();
+        final int numRacks = 1;
+        final int numSupersPerRack = 10;
+        final int numPortsPerSuper = 4;
+        final int numZonesPerHost = 2;
+        int rackStartNum = 0;
+        int supStartNum = 0;
+        final Map<String, SupervisorDetails> supMapRack0 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400, 8000, Collections.emptyMap(), 1.0);
+
+        //generate another rack of supervisors with less resources
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack1 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                200, 4000, Collections.emptyMap(), 1.0);
+
+        //generate some supervisors that are depleted of one resource
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack2 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                0, 8000, Collections.emptyMap(), 1.0);
+
+        //generate some that has a lot of memory but little of cpu
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack3 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                10, 8000 * 2 + 4000, Collections.emptyMap(), 1.0);
+
+        //generate some that has a lot of cpu but little of memory
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack4 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400 + 200 + 10, 1000, Collections.emptyMap(), 1.0);
+
+        supMap.putAll(supMapRack0);
+        supMap.putAll(supMapRack1);
+        supMap.putAll(supMapRack2);
+        supMap.putAll(supMapRack3);
+        supMap.putAll(supMapRack4);
+
+        Config config = createClusterConfig(100, 500, 500, null);
+        config.put(Config.TOPOLOGY_WORKER_MAX_HEAP_SIZE_MB, Double.MAX_VALUE);
+        INimbus iNimbus = new INimbusTest();
+
+        //create test DNSToSwitchMapping plugin
+        TestDNSToSwitchMapping testDNSToSwitchMapping =
+                new TestDNSToSwitchMapping(supMapRack0, supMapRack1, supMapRack2, supMapRack3, supMapRack4);
+
+        Config t1Conf = new Config();
+        t1Conf.putAll(config);
+        final List<String> t1FavoredHostNames = Arrays.asList("host-41", "host-42", "host-43");
+        t1Conf.put(Config.TOPOLOGY_SCHEDULER_FAVORED_NODES, t1FavoredHostNames);
+        final List<String> t1UnfavoredHostIds = Arrays.asList("host-1", "host-2", "host-3");
+        t1Conf.put(Config.TOPOLOGY_SCHEDULER_UNFAVORED_NODES, t1UnfavoredHostIds);
+        //generate topologies
+        TopologyDetails topo1 = genTopology("topo-1", t1Conf, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+
+        Config t2Conf = new Config();
+        t2Conf.putAll(config);
+        t2Conf.put(Config.TOPOLOGY_SCHEDULER_FAVORED_NODES, Arrays.asList("host-31", "host-32", "host-33"));
+        t2Conf.put(Config.TOPOLOGY_SCHEDULER_UNFAVORED_NODES, Arrays.asList("host-11", "host-12", "host-13"));
+        TopologyDetails topo2 = genTopology("topo-2", t2Conf, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+        Topologies topologies = new Topologies(topo1, topo2);
+        Cluster cluster = new Cluster(iNimbus, new ResourceMetrics(new StormMetricsRegistry()), supMap, new HashMap<>(), topologies, config);
+
+        List<String> supHostnames = new LinkedList<>();
+        for (SupervisorDetails sup : supMap.values()) {
+            supHostnames.add(sup.getHost());
+        }
+        Map<String, List<String>> rackToHosts = testDNSToSwitchMapping.getRackToHosts();
+        cluster.setNetworkTopography(rackToHosts);
+
+        NodeSorterHostProximity nodeSorter = new NodeSorterHostProximity(cluster, topo1, BaseResourceAwareStrategy.NodeSortType.DEFAULT_RAS);
+        nodeSorter.prepare(null);
+        List<ObjectResourcesItem> sortedRacks = StreamSupport.stream(nodeSorter.getSortedRacks().spliterator(), false)
+                .collect(Collectors.toList());
+        String rackSummaries = sortedRacks.stream()
+                .map(x -> String.format("Rack %s -> scheduled-cnt %d, min-avail %f, avg-avail %f, cpu %f, mem %f",
+                        x.id, nodeSorter.getScheduledExecCntByRackId().getOrDefault(x.id, new AtomicInteger(-1)).get(),
+                        x.minResourcePercent, x.avgResourcePercent,
+                        x.availableResources.getTotalCpu(),
+                        x.availableResources.getTotalMemoryMb()))
+                .collect(Collectors.joining("\n\t"));
+
+        Iterator<ObjectResourcesItem> it = sortedRacks.iterator();
+        // Ranked first since rack-000 has the most balanced set of resources
+        Assert.assertEquals("rack-000 should be ordered first", "rack-000", it.next().id);
+        // Ranked second since rack-1 has a balanced set of resources but less than rack-0
+        Assert.assertEquals("rack-001 should be ordered second", "rack-001", it.next().id);
+        // Ranked third since rack-4 has a lot of cpu but not a lot of memory
+        Assert.assertEquals("rack-004 should be ordered third", "rack-004", it.next().id);
+        // Ranked fourth since rack-3 has alot of memory but not cpu
+        Assert.assertEquals("rack-003 should be ordered fourth", "rack-003", it.next().id);
+        //Ranked last since rack-2 has not cpu resources
+        Assert.assertEquals("rack-00s2 should be ordered fifth", "rack-002", it.next().id);
+    }
+
+    /**
+     * Test if hosts are presented together regardless of resource availability.
+     * Supervisors are created with multiple Numa zones in such a manner that resources on two numa zones on the same host
+     * differ widely in resource availability.
+     */
+    @Test
+    public void testMultipleRacksWithHostProximity() {
+        final Map<String, SupervisorDetails> supMap = new HashMap<>();
+        final int numRacks = 1;
+        final int numSupersPerRack = 12;
+        final int numPortsPerSuper = 4;
+        final int numZonesPerHost = 3;
+        final double numaResourceMultiplier = 0.4;
+        int rackStartNum = 0;
+        int supStartNum = 0;
+
+        final Map<String, SupervisorDetails> supMapRack0 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400, 8000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate another rack of supervisors with less resources
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack1 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                200, 4000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate some supervisors that are depleted of one resource
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack2 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                0, 8000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate some that has a lot of memory but little of cpu
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack3 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                10, 8000 * 2 + 4000, Collections.emptyMap(),numaResourceMultiplier);
+
+        //generate some that has a lot of cpu but little of memory
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack4 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400 + 200 + 10, 1000, Collections.emptyMap(), numaResourceMultiplier);
+
+        supMap.putAll(supMapRack0);
+        supMap.putAll(supMapRack1);
+        supMap.putAll(supMapRack2);
+        supMap.putAll(supMapRack3);
+        supMap.putAll(supMapRack4);
+
+        Config config = createClusterConfig(100, 500, 500, null);
+        config.put(Config.TOPOLOGY_WORKER_MAX_HEAP_SIZE_MB, Double.MAX_VALUE);
+        INimbus iNimbus = new INimbusTest();
+
+        //create test DNSToSwitchMapping plugin
+        TestDNSToSwitchMapping testDNSToSwitchMapping =
+                new TestDNSToSwitchMapping(supMapRack0, supMapRack1, supMapRack2, supMapRack3, supMapRack4);
+
+        Config t1Conf = new Config();
+        t1Conf.putAll(config);
+        final List<String> t1FavoredHostNames = Arrays.asList("host-41", "host-42", "host-43");
+        t1Conf.put(Config.TOPOLOGY_SCHEDULER_FAVORED_NODES, t1FavoredHostNames);
+        final List<String> t1UnfavoredHostIds = Arrays.asList("host-1", "host-2", "host-3");
+        t1Conf.put(Config.TOPOLOGY_SCHEDULER_UNFAVORED_NODES, t1UnfavoredHostIds);
+        //generate topologies
+        TopologyDetails topo1 = genTopology("topo-1", t1Conf, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+
+        Config t2Conf = new Config();
+        t2Conf.putAll(config);
+        t2Conf.put(Config.TOPOLOGY_SCHEDULER_FAVORED_NODES, Arrays.asList("host-31", "host-32", "host-33"));
+        t2Conf.put(Config.TOPOLOGY_SCHEDULER_UNFAVORED_NODES, Arrays.asList("host-11", "host-12", "host-13"));
+        TopologyDetails topo2 = genTopology("topo-2", t2Conf, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+        Topologies topologies = new Topologies(topo1, topo2);
+        Cluster cluster = new Cluster(iNimbus, new ResourceMetrics(new StormMetricsRegistry()), supMap, new HashMap<>(), topologies, config);
+
+        cluster.setNetworkTopography(testDNSToSwitchMapping.getRackToHosts());
+
+        INodeSorter nodeSorter = new NodeSorterHostProximity(cluster, topo1);
+        nodeSorter.prepare(null);
+
+        Set<String> seenHosts = new HashSet<>();
+        String prevHost = null;
+        List<String> errLines = new ArrayList();
+        Map<String, String> nodeToHost = new RasNodes(cluster).getNodeIdToHostname();
+        for (String nodeId: nodeSorter.sortAllNodes()) {
+            String host = nodeToHost.getOrDefault(nodeId, "no-host-for-node-" + nodeId);
+            errLines.add(String.format("\tnodeId:%s, host:%s", nodeId, host));
+            if (!host.equals(prevHost) && seenHosts.contains(host)) {
+                String err = String.format("Host %s for node %s is out of order:\n\t%s", host, nodeId, String.join("\n\t", errLines));
+                Assert.fail(err);
+            }
+            seenHosts.add(host);
+            prevHost = host;
+        }
+        System.out.printf("DEBUG: Test Success: Hosts are listed together:\n\t%s\n", String.join("\n\t", errLines));

Review comment:
       Should we use `LOG.info` here?

##########
File path: storm-server/src/test/java/org/apache/storm/scheduler/resource/strategies/scheduling/sorter/TestNodeSorterHostProximity.java
##########
@@ -0,0 +1,1054 @@
+/*
+ * 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
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.storm.scheduler.resource.strategies.scheduling.sorter;
+
+import org.apache.logging.log4j.Level;
+import org.apache.logging.log4j.core.config.Configurator;
+import org.apache.storm.Config;
+import org.apache.storm.metric.StormMetricsRegistry;
+import org.apache.storm.networktopography.DNSToSwitchMapping;
+import org.apache.storm.scheduler.Cluster;
+import org.apache.storm.scheduler.ExecutorDetails;
+import org.apache.storm.scheduler.INimbus;
+import org.apache.storm.scheduler.IScheduler;
+import org.apache.storm.scheduler.SchedulerAssignment;
+import org.apache.storm.scheduler.SupervisorDetails;
+import org.apache.storm.scheduler.Topologies;
+import org.apache.storm.scheduler.TopologyDetails;
+import org.apache.storm.scheduler.WorkerSlot;
+import org.apache.storm.scheduler.resource.RasNodes;
+import org.apache.storm.scheduler.resource.ResourceAwareScheduler;
+import org.apache.storm.scheduler.resource.TestUtilsForResourceAwareScheduler;
+import org.apache.storm.scheduler.resource.normalization.NormalizedResourceRequest;
+import org.apache.storm.scheduler.resource.normalization.NormalizedResourcesExtension;
+import org.apache.storm.scheduler.resource.normalization.ResourceMetrics;
+import org.apache.storm.scheduler.resource.strategies.scheduling.BaseResourceAwareStrategy;
+import org.apache.storm.scheduler.resource.strategies.scheduling.DefaultResourceAwareStrategy;
+import org.apache.storm.scheduler.resource.strategies.scheduling.GenericResourceAwareStrategy;
+import org.apache.storm.scheduler.resource.strategies.scheduling.ObjectResourcesItem;
+import org.apache.storm.topology.TopologyBuilder;
+import org.junit.Assert;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeMap;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.stream.Collectors;
+import java.util.stream.StreamSupport;
+
+import static org.apache.storm.scheduler.resource.TestUtilsForResourceAwareScheduler.*;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+@ExtendWith({NormalizedResourcesExtension.class})
+public class TestNodeSorterHostProximity {
+    private static final Logger LOG = LoggerFactory.getLogger(TestNodeSorterHostProximity.class);
+    private static final int CURRENT_TIME = 1450418597;
+
+    protected Class getDefaultResourceAwareStrategyClass() {
+        return DefaultResourceAwareStrategy.class;
+    }
+
+    private Config createClusterConfig(double compPcore, double compOnHeap, double compOffHeap,
+                                       Map<String, Map<String, Number>> pools) {
+        Config config = TestUtilsForResourceAwareScheduler.createClusterConfig(compPcore, compOnHeap, compOffHeap, pools);
+        config.put(Config.TOPOLOGY_SCHEDULER_STRATEGY, getDefaultResourceAwareStrategyClass().getName());
+        return config;
+    }
+
+    private static class TestDNSToSwitchMapping implements DNSToSwitchMapping {
+        private final Map<String, String> hostToRackMap;
+        private final Map<String, List<String>> rackToHosts;
+
+        @SafeVarargs
+        public TestDNSToSwitchMapping(Map<String, SupervisorDetails>... racks) {
+            Set<String> seenHosts = new HashSet<>();
+            Map<String, String> hostToRackMap = new HashMap<>();
+            Map<String, List<String>> rackToHosts = new HashMap<>();
+            for (int rackNum = 0; rackNum < racks.length; rackNum++) {
+                String rack = String.format("rack-%03d", rackNum);
+                for (SupervisorDetails sup : racks[rackNum].values()) {
+                    hostToRackMap.put(sup.getHost(), rack);
+                    String host = sup.getHost();
+                    if (!seenHosts.contains(host)) {
+                        rackToHosts.computeIfAbsent(rack, rid -> new ArrayList<>()).add(host);
+                        seenHosts.add(host);
+                    }
+                }
+            }
+            this.hostToRackMap = Collections.unmodifiableMap(hostToRackMap);
+            this.rackToHosts = Collections.unmodifiableMap(rackToHosts);
+        }
+
+        /**
+         * Use the "rack-%03d" embedded in the name of the supervisor to determine the rack number.
+         *
+         * @param supervisorDetailsCollection
+         */
+        public TestDNSToSwitchMapping(Collection<SupervisorDetails> supervisorDetailsCollection) {
+            Set<String> seenHosts = new HashSet<>();
+            Map<String, String> hostToRackMap = new HashMap<>();
+            Map<String, List<String>> rackToHosts = new HashMap<>();
+
+            for (SupervisorDetails supervisorDetails: supervisorDetailsCollection) {
+                String rackId = supervisorIdToRackName(supervisorDetails.getId());
+                hostToRackMap.put(supervisorDetails.getHost(), rackId);
+                String host = supervisorDetails.getHost();
+                if (!seenHosts.contains(host)) {
+                    rackToHosts.computeIfAbsent(rackId, rid -> new ArrayList<>()).add(host);
+                    seenHosts.add(host);
+                }
+            }
+            this.hostToRackMap = Collections.unmodifiableMap(hostToRackMap);
+            this.rackToHosts = Collections.unmodifiableMap(rackToHosts);
+        }
+
+        @Override
+        public Map<String, String> resolve(List<String> names) {
+            return hostToRackMap;
+        }
+
+        public Map<String, List<String>> getRackToHosts() {
+            return rackToHosts;
+        }
+    }
+
+    /**
+     * Test whether strategy will choose correct rack.
+     */
+    @Test
+    public void testMultipleRacks() {
+        final Map<String, SupervisorDetails> supMap = new HashMap<>();
+        final int numRacks = 1;
+        final int numSupersPerRack = 10;
+        final int numPortsPerSuper = 4;
+        final int numZonesPerHost = 1;
+        final double numaResourceMultiplier = 1.0;
+        int rackStartNum = 0;
+        int supStartNum = 0;
+
+        final Map<String, SupervisorDetails> supMapRack0 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400, 8000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate another rack of supervisors with less resources
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack1 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                200, 4000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate some supervisors that are depleted of one resource
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack2 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                0, 8000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate some that has a lot of memory but little of cpu
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack3 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                10, 8000 * 2 + 4000, Collections.emptyMap(),numaResourceMultiplier);
+
+        //generate some that has a lot of cpu but little of memory
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack4 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400 + 200 + 10, 1000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //Generate some that have neither resource, to verify that the strategy will prioritize this last
+        //Also put a generic resource with 0 value in the resources list, to verify that it doesn't affect the sorting
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack5 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                0.0, 0.0, Collections.singletonMap("gpu.count", 0.0), numaResourceMultiplier);
+
+        supMap.putAll(supMapRack0);
+        supMap.putAll(supMapRack1);
+        supMap.putAll(supMapRack2);
+        supMap.putAll(supMapRack3);
+        supMap.putAll(supMapRack4);
+        supMap.putAll(supMapRack5);
+
+        Config config = createClusterConfig(100, 500, 500, null);
+        config.put(Config.TOPOLOGY_WORKER_MAX_HEAP_SIZE_MB, Double.MAX_VALUE);
+        INimbus iNimbus = new INimbusTest();
+
+        //create test DNSToSwitchMapping plugin
+        TestDNSToSwitchMapping testDNSToSwitchMapping =
+                new TestDNSToSwitchMapping(supMapRack0, supMapRack1, supMapRack2, supMapRack3, supMapRack4, supMapRack5);
+
+        //generate topologies
+        TopologyDetails topo1 = genTopology("topo-1", config, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+        TopologyDetails topo2 = genTopology("topo-2", config, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+        Topologies topologies = new Topologies(topo1, topo2);
+        Cluster cluster = new Cluster(iNimbus, new ResourceMetrics(new StormMetricsRegistry()), supMap, new HashMap<>(), topologies, config);
+
+        List<String> supHostnames = new LinkedList<>();
+        for (SupervisorDetails sup : supMap.values()) {
+            supHostnames.add(sup.getHost());
+        }
+        Map<String, List<String>> rackToHosts = testDNSToSwitchMapping.getRackToHosts();
+        cluster.setNetworkTopography(rackToHosts);
+        System.out.println("DEBUG: rackToHosts: " + rackToHosts.toString());
+
+        NodeSorterHostProximity nodeSorter = new NodeSorterHostProximity(cluster, topo1, BaseResourceAwareStrategy.NodeSortType.DEFAULT_RAS);
+        nodeSorter.prepare(null);
+        List<ObjectResourcesItem> sortedRacks = StreamSupport.stream(nodeSorter.getSortedRacks().spliterator(), false)
+                .collect(Collectors.toList());
+        String rackSummaries = sortedRacks.stream()
+                .map(x -> String.format("Rack %s -> scheduled-cnt %d, min-avail %f, avg-avail %f, cpu %f, mem %f",
+                        x.id, nodeSorter.getScheduledExecCntByRackId().getOrDefault(x.id, new AtomicInteger(-1)).get(),
+                        x.minResourcePercent, x.avgResourcePercent,
+                        x.availableResources.getTotalCpu(),
+                        x.availableResources.getTotalMemoryMb()))
+                .collect(Collectors.joining("\n\t"));
+        Assert.assertEquals(rackSummaries + "\n# of racks sorted", 6, sortedRacks.size());
+        Iterator<ObjectResourcesItem> it = sortedRacks.iterator();
+        Assert.assertEquals(rackSummaries + "\nrack-000 should be ordered first since it has the most balanced set of resources", "rack-000", it.next().id);
+        Assert.assertEquals(rackSummaries + "\nrack-001 should be ordered second since it has a balanced set of resources but less than rack-000", "rack-001", it.next().id);
+        Assert.assertEquals(rackSummaries + "\nrack-004 should be ordered third since it has a lot of cpu but not a lot of memory", "rack-004", it.next().id);
+        Assert.assertEquals(rackSummaries + "\nrack-003 should be ordered fourth since it has a lot of memory but not cpu", "rack-003", it.next().id);
+        Assert.assertEquals(rackSummaries + "\nrack-002 should be ordered fifth since it has not cpu resources", "rack-002", it.next().id);
+        Assert.assertEquals(rackSummaries + "\nRack-005 should be ordered sixth since it has neither CPU nor memory available", "rack-005", it.next().id);
+    }
+
+    /**
+     * Test whether strategy will choose correct rack.
+     */
+    @Test
+    public void testMultipleRacksWithFavoritism() {
+        final Map<String, SupervisorDetails> supMap = new HashMap<>();
+        final int numRacks = 1;
+        final int numSupersPerRack = 10;
+        final int numPortsPerSuper = 4;
+        final int numZonesPerHost = 2;
+        int rackStartNum = 0;
+        int supStartNum = 0;
+        final Map<String, SupervisorDetails> supMapRack0 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400, 8000, Collections.emptyMap(), 1.0);
+
+        //generate another rack of supervisors with less resources
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack1 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                200, 4000, Collections.emptyMap(), 1.0);
+
+        //generate some supervisors that are depleted of one resource
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack2 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                0, 8000, Collections.emptyMap(), 1.0);
+
+        //generate some that has a lot of memory but little of cpu
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack3 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                10, 8000 * 2 + 4000, Collections.emptyMap(), 1.0);
+
+        //generate some that has a lot of cpu but little of memory
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack4 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400 + 200 + 10, 1000, Collections.emptyMap(), 1.0);
+
+        supMap.putAll(supMapRack0);
+        supMap.putAll(supMapRack1);
+        supMap.putAll(supMapRack2);
+        supMap.putAll(supMapRack3);
+        supMap.putAll(supMapRack4);
+
+        Config config = createClusterConfig(100, 500, 500, null);
+        config.put(Config.TOPOLOGY_WORKER_MAX_HEAP_SIZE_MB, Double.MAX_VALUE);
+        INimbus iNimbus = new INimbusTest();
+
+        //create test DNSToSwitchMapping plugin
+        TestDNSToSwitchMapping testDNSToSwitchMapping =
+                new TestDNSToSwitchMapping(supMapRack0, supMapRack1, supMapRack2, supMapRack3, supMapRack4);
+
+        Config t1Conf = new Config();
+        t1Conf.putAll(config);
+        final List<String> t1FavoredHostNames = Arrays.asList("host-41", "host-42", "host-43");
+        t1Conf.put(Config.TOPOLOGY_SCHEDULER_FAVORED_NODES, t1FavoredHostNames);
+        final List<String> t1UnfavoredHostIds = Arrays.asList("host-1", "host-2", "host-3");
+        t1Conf.put(Config.TOPOLOGY_SCHEDULER_UNFAVORED_NODES, t1UnfavoredHostIds);
+        //generate topologies
+        TopologyDetails topo1 = genTopology("topo-1", t1Conf, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+
+        Config t2Conf = new Config();
+        t2Conf.putAll(config);
+        t2Conf.put(Config.TOPOLOGY_SCHEDULER_FAVORED_NODES, Arrays.asList("host-31", "host-32", "host-33"));
+        t2Conf.put(Config.TOPOLOGY_SCHEDULER_UNFAVORED_NODES, Arrays.asList("host-11", "host-12", "host-13"));
+        TopologyDetails topo2 = genTopology("topo-2", t2Conf, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+        Topologies topologies = new Topologies(topo1, topo2);
+        Cluster cluster = new Cluster(iNimbus, new ResourceMetrics(new StormMetricsRegistry()), supMap, new HashMap<>(), topologies, config);
+
+        List<String> supHostnames = new LinkedList<>();
+        for (SupervisorDetails sup : supMap.values()) {
+            supHostnames.add(sup.getHost());
+        }
+        Map<String, List<String>> rackToHosts = testDNSToSwitchMapping.getRackToHosts();
+        cluster.setNetworkTopography(rackToHosts);
+
+        NodeSorterHostProximity nodeSorter = new NodeSorterHostProximity(cluster, topo1, BaseResourceAwareStrategy.NodeSortType.DEFAULT_RAS);
+        nodeSorter.prepare(null);
+        List<ObjectResourcesItem> sortedRacks = StreamSupport.stream(nodeSorter.getSortedRacks().spliterator(), false)
+                .collect(Collectors.toList());
+        String rackSummaries = sortedRacks.stream()
+                .map(x -> String.format("Rack %s -> scheduled-cnt %d, min-avail %f, avg-avail %f, cpu %f, mem %f",
+                        x.id, nodeSorter.getScheduledExecCntByRackId().getOrDefault(x.id, new AtomicInteger(-1)).get(),
+                        x.minResourcePercent, x.avgResourcePercent,
+                        x.availableResources.getTotalCpu(),
+                        x.availableResources.getTotalMemoryMb()))
+                .collect(Collectors.joining("\n\t"));
+
+        Iterator<ObjectResourcesItem> it = sortedRacks.iterator();
+        // Ranked first since rack-000 has the most balanced set of resources
+        Assert.assertEquals("rack-000 should be ordered first", "rack-000", it.next().id);
+        // Ranked second since rack-1 has a balanced set of resources but less than rack-0
+        Assert.assertEquals("rack-001 should be ordered second", "rack-001", it.next().id);
+        // Ranked third since rack-4 has a lot of cpu but not a lot of memory
+        Assert.assertEquals("rack-004 should be ordered third", "rack-004", it.next().id);
+        // Ranked fourth since rack-3 has alot of memory but not cpu
+        Assert.assertEquals("rack-003 should be ordered fourth", "rack-003", it.next().id);
+        //Ranked last since rack-2 has not cpu resources
+        Assert.assertEquals("rack-00s2 should be ordered fifth", "rack-002", it.next().id);
+    }
+
+    /**
+     * Test if hosts are presented together regardless of resource availability.
+     * Supervisors are created with multiple Numa zones in such a manner that resources on two numa zones on the same host
+     * differ widely in resource availability.
+     */
+    @Test
+    public void testMultipleRacksWithHostProximity() {
+        final Map<String, SupervisorDetails> supMap = new HashMap<>();
+        final int numRacks = 1;
+        final int numSupersPerRack = 12;
+        final int numPortsPerSuper = 4;
+        final int numZonesPerHost = 3;
+        final double numaResourceMultiplier = 0.4;
+        int rackStartNum = 0;
+        int supStartNum = 0;
+
+        final Map<String, SupervisorDetails> supMapRack0 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400, 8000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate another rack of supervisors with less resources
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack1 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                200, 4000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate some supervisors that are depleted of one resource
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack2 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                0, 8000, Collections.emptyMap(), numaResourceMultiplier);
+
+        //generate some that has a lot of memory but little of cpu
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack3 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                10, 8000 * 2 + 4000, Collections.emptyMap(),numaResourceMultiplier);
+
+        //generate some that has a lot of cpu but little of memory
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack4 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400 + 200 + 10, 1000, Collections.emptyMap(), numaResourceMultiplier);
+
+        supMap.putAll(supMapRack0);
+        supMap.putAll(supMapRack1);
+        supMap.putAll(supMapRack2);
+        supMap.putAll(supMapRack3);
+        supMap.putAll(supMapRack4);
+
+        Config config = createClusterConfig(100, 500, 500, null);
+        config.put(Config.TOPOLOGY_WORKER_MAX_HEAP_SIZE_MB, Double.MAX_VALUE);
+        INimbus iNimbus = new INimbusTest();
+
+        //create test DNSToSwitchMapping plugin
+        TestDNSToSwitchMapping testDNSToSwitchMapping =
+                new TestDNSToSwitchMapping(supMapRack0, supMapRack1, supMapRack2, supMapRack3, supMapRack4);
+
+        Config t1Conf = new Config();
+        t1Conf.putAll(config);
+        final List<String> t1FavoredHostNames = Arrays.asList("host-41", "host-42", "host-43");
+        t1Conf.put(Config.TOPOLOGY_SCHEDULER_FAVORED_NODES, t1FavoredHostNames);
+        final List<String> t1UnfavoredHostIds = Arrays.asList("host-1", "host-2", "host-3");
+        t1Conf.put(Config.TOPOLOGY_SCHEDULER_UNFAVORED_NODES, t1UnfavoredHostIds);
+        //generate topologies
+        TopologyDetails topo1 = genTopology("topo-1", t1Conf, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+
+        Config t2Conf = new Config();
+        t2Conf.putAll(config);
+        t2Conf.put(Config.TOPOLOGY_SCHEDULER_FAVORED_NODES, Arrays.asList("host-31", "host-32", "host-33"));
+        t2Conf.put(Config.TOPOLOGY_SCHEDULER_UNFAVORED_NODES, Arrays.asList("host-11", "host-12", "host-13"));
+        TopologyDetails topo2 = genTopology("topo-2", t2Conf, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+        Topologies topologies = new Topologies(topo1, topo2);
+        Cluster cluster = new Cluster(iNimbus, new ResourceMetrics(new StormMetricsRegistry()), supMap, new HashMap<>(), topologies, config);
+
+        cluster.setNetworkTopography(testDNSToSwitchMapping.getRackToHosts());
+
+        INodeSorter nodeSorter = new NodeSorterHostProximity(cluster, topo1);
+        nodeSorter.prepare(null);
+
+        Set<String> seenHosts = new HashSet<>();
+        String prevHost = null;
+        List<String> errLines = new ArrayList();
+        Map<String, String> nodeToHost = new RasNodes(cluster).getNodeIdToHostname();
+        for (String nodeId: nodeSorter.sortAllNodes()) {
+            String host = nodeToHost.getOrDefault(nodeId, "no-host-for-node-" + nodeId);
+            errLines.add(String.format("\tnodeId:%s, host:%s", nodeId, host));
+            if (!host.equals(prevHost) && seenHosts.contains(host)) {
+                String err = String.format("Host %s for node %s is out of order:\n\t%s", host, nodeId, String.join("\n\t", errLines));
+                Assert.fail(err);
+            }
+            seenHosts.add(host);
+            prevHost = host;
+        }
+        System.out.printf("DEBUG: Test Success: Hosts are listed together:\n\t%s\n", String.join("\n\t", errLines));
+    }
+
+    /**
+     * Racks should be returned in order of decreasing capacity.
+     */
+    @Test
+    public void testMultipleRacksOrderedByCapacity() {
+        final Map<String, SupervisorDetails> supMap = new HashMap<>();
+        final int numRacks = 1;
+        final int numSupersPerRack = 10;
+        final int numPortsPerSuper = 4;
+        final int numZonesPerHost = 1;
+        final double numaResourceMultiplier = 1.0;
+        int rackStartNum = 0;
+        int supStartNum = 0;
+
+        final Map<String, SupervisorDetails> supMapRack0 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                600, 8000 - rackStartNum, Collections.emptyMap(), numaResourceMultiplier);
+
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack1 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                500, 8000 - rackStartNum, Collections.emptyMap(), numaResourceMultiplier);
+
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack2 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                400, 8000 - rackStartNum, Collections.emptyMap(), numaResourceMultiplier);
+
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack3 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                300, 8000 - rackStartNum, Collections.emptyMap(),numaResourceMultiplier);
+
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack4 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                200, 8000 - rackStartNum, Collections.emptyMap(), numaResourceMultiplier);
+
+        // too small to hold topology
+        supStartNum += numSupersPerRack;
+        final Map<String, SupervisorDetails> supMapRack5 = genSupervisorsWithRacksAndNuma(
+                numRacks, numSupersPerRack, numZonesPerHost, numPortsPerSuper, rackStartNum++, supStartNum,
+                100, 8000 - rackStartNum, Collections.singletonMap("gpu.count", 0.0), numaResourceMultiplier);
+
+        supMap.putAll(supMapRack0);
+        supMap.putAll(supMapRack1);
+        supMap.putAll(supMapRack2);
+        supMap.putAll(supMapRack3);
+        supMap.putAll(supMapRack4);
+        supMap.putAll(supMapRack5);
+
+        Config config = createClusterConfig(100, 500, 500, null);
+        config.put(Config.TOPOLOGY_WORKER_MAX_HEAP_SIZE_MB, Double.MAX_VALUE);
+        INimbus iNimbus = new INimbusTest();
+
+        //create test DNSToSwitchMapping plugin
+        TestDNSToSwitchMapping testDNSToSwitchMapping =
+                new TestDNSToSwitchMapping(supMapRack0, supMapRack1, supMapRack2, supMapRack3, supMapRack4, supMapRack5);
+
+        //generate topologies
+        TopologyDetails topo1 = genTopology("topo-1", config, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+        TopologyDetails topo2 = genTopology("topo-2", config, 8, 0, 2, 0, CURRENT_TIME - 2, 10, "user");
+
+        Topologies topologies = new Topologies(topo1, topo2);
+        Cluster cluster = new Cluster(iNimbus, new ResourceMetrics(new StormMetricsRegistry()), supMap, new HashMap<>(), topologies, config);
+
+        cluster.setNetworkTopography(testDNSToSwitchMapping.getRackToHosts());
+
+        NodeSorterHostProximity nodeSorter = new NodeSorterHostProximity(cluster, topo1);
+        nodeSorter.prepare(null);
+        List<ObjectResourcesItem> sortedRacks = StreamSupport.stream(nodeSorter.getSortedRacks().spliterator(), false)
+                .collect(Collectors.toList());
+        String rackSummaries = sortedRacks
+                .stream()
+                .map(x -> String.format("Rack %s -> scheduled-cnt %d, min-avail %f, avg-avail %f, cpu %f, mem %f",
+                        x.id, nodeSorter.getScheduledExecCntByRackId().getOrDefault(x.id, new AtomicInteger(-1)).get(),
+                        x.minResourcePercent, x.avgResourcePercent,
+                        x.availableResources.getTotalCpu(),
+                        x.availableResources.getTotalMemoryMb()))
+                .collect(Collectors.joining("\n\t"));
+        NormalizedResourceRequest topoResourceRequest = topo1.getApproximateTotalResources();
+        String topoRequest = String.format("Topo %s, approx-requested-resources %s", topo1.getId(), topoResourceRequest.toString());
+        //Assert.assertEquals(rackSummaries + "\n# of racks sorted", 6, sortedRacks.size());
+        Iterator<ObjectResourcesItem> it = sortedRacks.iterator();
+        Assert.assertEquals(topoRequest + "\n\t" + rackSummaries + "\nRack-000 should be ordered first since it has the largest capacity", "rack-000", it.next().id);
+        Assert.assertEquals(topoRequest + "\n\t" + rackSummaries + "\nrack-001 should be ordered second since it smaller than rack-000", "rack-001", it.next().id);
+        Assert.assertEquals(topoRequest + "\n\t" + rackSummaries + "\nrack-002 should be ordered third since it is smaller than rack-001", "rack-002", it.next().id);
+        Assert.assertEquals(topoRequest + "\n\t" + rackSummaries + "\nrack-003 should be ordered fourth since it since it is smaller than rack-002", "rack-003", it.next().id);
+        Assert.assertEquals(topoRequest + "\n\t" + rackSummaries + "\nrack-004 should be ordered fifth since it since it is smaller than rack-003", "rack-004", it.next().id);
+        Assert.assertEquals(topoRequest + "\n\t" + rackSummaries + "\nrack-005 should be ordered last since it since it is has smallest capacity", "rack-005", it.next().id);
+    }
+
+    /**
+     * Schedule two topologies, once with special resources and another without.
+     * There are enough special resources to hold one topology with special resource ("my.gpu").
+     * If the sort order is incorrect, scheduling will not succeed.
+     */
+    @Test
+    public void testAntiAffinityWithMultipleTopologies() {
+        INimbus iNimbus = new INimbusTest();
+        Map<String, SupervisorDetails> supMap = genSupervisorsWithRacks(1, 40, 66, 0, 0, 4700, 226200, new HashMap<>());
+        HashMap<String, Double> extraResources = new HashMap<>();
+        extraResources.put("my.gpu", 1.0);
+        supMap.putAll(genSupervisorsWithRacks(1, 40, 66, 1, 0, 4700, 226200, extraResources));
+
+        Config config = new Config();
+        config.putAll(createGrasClusterConfig(88, 775, 25, null, null));
+        //config.put(Config.TOPOLOGY_SCHEDULER_STRATEGY, GenericResourceAwareStrategy.class.getName());
+
+        IScheduler scheduler = new ResourceAwareScheduler();
+        scheduler.prepare(config, new StormMetricsRegistry());
+
+        TopologyDetails tdSimple = genTopology("topology-simple", config, 1,
+                5, 100, 300, 0, 0, "user", 8192);
+
+        //Schedule the simple topology first
+        Topologies topologies = new Topologies(tdSimple);
+        Cluster cluster = new Cluster(iNimbus, new ResourceMetrics(new StormMetricsRegistry()), supMap, new HashMap<>(), topologies, config);
+
+        {
+            NodeSorterHostProximity nodeSorter = new NodeSorterHostProximity(cluster, tdSimple);
+            for (ExecutorDetails exec : tdSimple.getExecutors()) {
+                nodeSorter.prepare(exec);
+                List<ObjectResourcesItem> sortedRacks = StreamSupport
+                        .stream(nodeSorter.getSortedRacks().spliterator(), false)
+                        .collect(Collectors.toList());
+                String rackSummaries = StreamSupport
+                        .stream(sortedRacks.spliterator(), false)
+                        .map(x -> String.format("Rack %s -> scheduled-cnt %d, min-avail %f, avg-avail %f, cpu %f, mem %f",
+                                x.id, nodeSorter.getScheduledExecCntByRackId().getOrDefault(x.id, new AtomicInteger(-1)).get(),
+                                x.minResourcePercent, x.avgResourcePercent,
+                                x.availableResources.getTotalCpu(),
+                                x.availableResources.getTotalMemoryMb()))
+                        .collect(Collectors.joining("\n\t"));
+                NormalizedResourceRequest topoResourceRequest = tdSimple.getApproximateTotalResources();
+                String topoRequest = String.format("Topo %s, approx-requested-resources %s", tdSimple.getId(), topoResourceRequest.toString());
+                Assert.assertEquals(rackSummaries + "\n# of racks sorted", 2, sortedRacks.size());
+                Assert.assertEquals(rackSummaries + "\nFirst rack sorted", "rack-000", sortedRacks.get(0).id);
+                Assert.assertEquals(rackSummaries + "\nSecond rack sorted", "rack-001", sortedRacks.get(1).id);
+            }
+        }
+
+        scheduler.schedule(topologies, cluster);
+
+        TopologyBuilder builder = topologyBuilder(1, 5, 100, 300);
+        builder.setBolt("gpu-bolt", new TestBolt(), 40)
+                .addResource("my.gpu", 1.0)
+                .shuffleGrouping("spout-0");
+        TopologyDetails tdGpu = topoToTopologyDetails("topology-gpu", config, builder.createTopology(), 0, 0,"user", 8192);
+
+        //Now schedule GPU but with the simple topology in place.
+        topologies = new Topologies(tdSimple, tdGpu);
+        cluster = new Cluster(cluster, topologies);
+        {
+            NodeSorterHostProximity nodeSorter = new NodeSorterHostProximity(cluster, tdGpu);
+            for (ExecutorDetails exec : tdGpu.getExecutors()) {
+                String comp = tdGpu.getComponentFromExecutor(exec);
+                nodeSorter.prepare(exec);
+                List<ObjectResourcesItem> sortedRacks = StreamSupport
+                        .stream(nodeSorter.getSortedRacks().spliterator(), false).collect(Collectors.toList());
+                String rackSummaries = sortedRacks.stream()
+                        .map(x -> String.format("Rack %s -> scheduled-cnt %d, min-avail %f, avg-avail %f, cpu %f, mem %f",
+                                x.id, nodeSorter.getScheduledExecCntByRackId().getOrDefault(x.id, new AtomicInteger(-1)).get(),
+                                x.minResourcePercent, x.avgResourcePercent,
+                                x.availableResources.getTotalCpu(),
+                                x.availableResources.getTotalMemoryMb()))
+                        .collect(Collectors.joining("\n\t"));
+                NormalizedResourceRequest topoResourceRequest = tdSimple.getApproximateTotalResources();
+                String topoRequest = String.format("Topo %s, approx-requested-resources %s", tdSimple.getId(), topoResourceRequest.toString());
+                Assert.assertEquals(rackSummaries + "\n# of racks sorted", 2, sortedRacks.size());
+                if (comp.equals("gpu-bolt")) {
+                    Assert.assertEquals(rackSummaries + "\nFirst rack sorted for " + comp, "rack-001", sortedRacks.get(0).id);
+                    Assert.assertEquals(rackSummaries + "\nSecond rack sorted for " + comp, "rack-000", sortedRacks.get(1).id);
+                } else {
+                    Assert.assertEquals(rackSummaries + "\nFirst rack sorted for " + comp, "rack-000", sortedRacks.get(0).id);
+                    Assert.assertEquals(rackSummaries + "\nSecond rack sorted for " + comp, "rack-001", sortedRacks.get(1).id);
+                }
+            }
+        }
+
+        scheduler.schedule(topologies, cluster);
+
+        Map<String, SchedulerAssignment> assignments = new TreeMap<>(cluster.getAssignments());
+        assertEquals(2, assignments.size());
+
+        Map<String, Map<String, AtomicLong>> topoPerRackCount = new HashMap<>();
+        for (Map.Entry<String, SchedulerAssignment> entry: assignments.entrySet()) {
+            SchedulerAssignment sa = entry.getValue();
+            Map<String, AtomicLong> slotsPerRack = new TreeMap<>();
+            for (WorkerSlot slot : sa.getSlots()) {
+                String nodeId = slot.getNodeId();
+                String rack = supervisorIdToRackName(nodeId);
+                slotsPerRack.computeIfAbsent(rack, (r) -> new AtomicLong(0)).incrementAndGet();
+            }
+            LOG.info("{} => {}", entry.getKey(), slotsPerRack);
+            topoPerRackCount.put(entry.getKey(), slotsPerRack);
+        }
+
+        Map<String, AtomicLong> simpleCount = topoPerRackCount.get("topology-simple-0");
+        assertNotNull(simpleCount);
+        //Because the simple topology was scheduled first we want to be sure that it didn't put anything on
+        // the GPU nodes.
+        assertEquals(1, simpleCount.size()); //Only 1 rack is in use
+        assertFalse(simpleCount.containsKey("r001")); //r001 is the second rack with GPUs
+        assertTrue(simpleCount.containsKey("r000")); //r000 is the first rack with no GPUs
+
+        //We don't really care too much about the scheduling of topology-gpu-0, because it was scheduled.
+    }
+
+    /**
+     * Free one-fifth of WorkerSlots.
+     */
+    private void freeSomeWorkerSlots(Cluster cluster) {
+        Map<String, SchedulerAssignment> assignmentMap = cluster.getAssignments();
+        for (SchedulerAssignment schedulerAssignment: assignmentMap.values()) {
+            int i = 0;
+            List<WorkerSlot> slotsToKill = new ArrayList<>();
+            for (WorkerSlot workerSlot: schedulerAssignment.getSlots()) {
+                i++;
+                if (i % 5 == 0) {
+                    slotsToKill.add(workerSlot);
+                }
+            }
+            cluster.freeSlots(slotsToKill);
+        }
+    }
+
+    private void activateTrace() {
+        List<Class> classesToDebug = Arrays.asList(this.getClass(),
+                BaseResourceAwareStrategy.class, ResourceAwareScheduler.class,
+                NodeSorterHostProximity.class, Cluster.class
+        );
+        Level logLevel = Level.TRACE ; // switch to Level.DEBUG for verbose otherwise Level.INFO
+        classesToDebug.forEach(x -> Configurator.setLevel(x.getName(), logLevel));
+    }
+
+    /**
+     * If the topology is too large for one rack, it should be partially scheduled onto the next rack (and next rack only).
+     */
+    @Test
+    public void testFillUpRackAndSpilloverToNextRack() {
+        //activateTrace();

Review comment:
       Remove if not used?




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