MAPREDUCE-3641. Making CapacityScheduler more conservative so as to assign only one off-switch container in a single scheduling iteration. Contributed by Arun C Murthy.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1232182 13f79535-47bb-0310-9956-ffa450edef68

hadoop-mapreduce-project/CHANGES.txt

@@ -183,6 +183,10 @@ Release 0.23.1 - Unreleased
     MAPREDUCE-3553. Add support for data returned when exceptions thrown from web 
     service apis to be in either xml or in JSON. (Thomas Graves via mahadev)
 
+    MAPREDUCE-3641. Making CapacityScheduler more conservative so as to 
+    assign only one off-switch container in a single scheduling
+    iteration. (Arun C Murthy via vinodkv)
+
   OPTIMIZATIONS
 
     MAPREDUCE-3567. Extraneous JobConf objects in AM heap. (Vinod Kumar

hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/resource/Resources.java

@@ -26,8 +26,26 @@ import org.apache.hadoop.yarn.util.Records;
 @Private
 @Evolving
 public class Resources {
+  
   // Java doesn't have const :(
-  private static final Resource NONE = createResource(0);
+  private static final Resource NONE = new Resource() {
+
+    @Override
+    public int getMemory() {
+      return 0;
+    }
+
+    @Override
+    public void setMemory(int memory) {
+      throw new RuntimeException("NONE cannot be modified!");
+    }
+
+    @Override
+    public int compareTo(Resource o) {
+      return (0 - o.getMemory());
+    }
+    
+  };
 
   public static Resource createResource(int memory) {
     Resource resource = Records.newRecord(Resource.class);
@@ -36,7 +54,6 @@ public class Resources {
   }
 
   public static Resource none() {
-    assert NONE.getMemory() == 0 : "NONE should be empty";
     return NONE;
   }
 

hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/CSAssignment.java

@@ -0,0 +1,48 @@
+/**
+* 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.hadoop.yarn.server.resourcemanager.scheduler.capacity;
+
+import org.apache.hadoop.classification.InterfaceAudience.Private;
+import org.apache.hadoop.classification.InterfaceStability.Unstable;
+import org.apache.hadoop.yarn.api.records.Resource;
+import org.apache.hadoop.yarn.server.resourcemanager.scheduler.NodeType;
+
+@Private
+@Unstable
+public class CSAssignment {
+  final private Resource resource;
+  final private NodeType type;
+  
+  public CSAssignment(Resource resource, NodeType type) {
+    this.resource = resource;
+    this.type = type;
+  }
+
+  public Resource getResource() {
+    return resource;
+  }
+
+  public NodeType getType() {
+    return type;
+  }
+  
+  @Override
+  public String toString() {
+    return resource.getMemory() + ":" + type;
+  }
+}

hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/CSQueue.java

@@ -155,9 +155,10 @@ extends org.apache.hadoop.yarn.server.resourcemanager.scheduler.Queue {
    * Assign containers to applications in the queue or it's children (if any).
    * @param clusterResource the resource of the cluster.
    * @param node node on which resources are available
-   * @return the resource that is being assigned.
+   * @return the assignment
    */
-  public Resource assignContainers(Resource clusterResource, SchedulerNode node);
+  public CSAssignment assignContainers(
+      Resource clusterResource, SchedulerNode node);
   
   /**
    * A container assigned to the queue has completed.

hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/LeafQueue.java

@@ -19,7 +19,6 @@
 package org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity;
 
 import java.io.IOException;
-import java.net.InetSocketAddress;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.Collections;
@@ -35,7 +34,6 @@ import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.classification.InterfaceAudience.Private;
 import org.apache.hadoop.classification.InterfaceStability.Unstable;
-import org.apache.hadoop.net.NetUtils;
 import org.apache.hadoop.security.AccessControlException;
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.security.authorize.AccessControlList;
@@ -703,8 +701,11 @@ public class LeafQueue implements CSQueue {
     return applicationsMap.get(applicationAttemptId);
   }
 
+  private static final CSAssignment NULL_ASSIGNMENT =
+      new CSAssignment(Resources.createResource(0), NodeType.NODE_LOCAL);
+  
   @Override
-  public synchronized Resource 
+  public synchronized CSAssignment 
   assignContainers(Resource clusterResource, SchedulerNode node) {
 
     if(LOG.isDebugEnabled()) {
@@ -717,8 +718,11 @@ public class LeafQueue implements CSQueue {
     if (reservedContainer != null) {
       SchedulerApp application = 
           getApplication(reservedContainer.getApplicationAttemptId());
-      return assignReservedContainer(application, node, reservedContainer, 
-          clusterResource);
+      return new CSAssignment(
+          assignReservedContainer(application, node, reservedContainer, 
+              clusterResource),
+          NodeType.NODE_LOCAL); // Don't care about locality constraints 
+                                // for reserved containers
     }
     
     // Try to assign containers to applications in order
@@ -746,7 +750,7 @@ public class LeafQueue implements CSQueue {
           // Are we going over limits by allocating to this application?
           // Maximum Capacity of the queue
           if (!assignToQueue(clusterResource, required)) {
-            return Resources.none();
+            return NULL_ASSIGNMENT;
           }
 
           // User limits
@@ -760,24 +764,23 @@ public class LeafQueue implements CSQueue {
           application.addSchedulingOpportunity(priority);
           
           // Try to schedule
-          Resource assigned = 
+          CSAssignment assignment =  
             assignContainersOnNode(clusterResource, node, application, priority, 
                 null);
-  
+          
+          Resource assigned = assignment.getResource();
+            
           // Did we schedule or reserve a container?
           if (Resources.greaterThan(assigned, Resources.none())) {
-            Resource assignedResource = 
-              application.getResourceRequest(priority, RMNode.ANY).getCapability();
 
             // Book-keeping
-            allocateResource(clusterResource, 
-                application, assignedResource);
+            allocateResource(clusterResource, application, assigned);
             
             // Reset scheduling opportunities
             application.resetSchedulingOpportunities(priority);
             
             // Done
-            return assignedResource; 
+            return assignment;
           } else {
             // Do not assign out of order w.r.t priorities
             break;
@@ -792,7 +795,7 @@ public class LeafQueue implements CSQueue {
       application.showRequests();
     }
   
-    return Resources.none();
+    return NULL_ASSIGNMENT;
 
   }
 
@@ -809,11 +812,12 @@ public class LeafQueue implements CSQueue {
               container.getId(), 
               SchedulerUtils.UNRESERVED_CONTAINER), 
           RMContainerEventType.RELEASED);
-      return container.getResource();
+      return container.getResource(); // Ugh, return resource to force re-sort
     }
 
     // Try to assign if we have sufficient resources
-    assignContainersOnNode(clusterResource, node, application, priority, rmContainer);
+    assignContainersOnNode(clusterResource, node, application, priority, 
+        rmContainer);
     
     // Doesn't matter... since it's already charged for at time of reservation
     // "re-reservation" is *free*
@@ -966,7 +970,7 @@ public class LeafQueue implements CSQueue {
     return (((starvation + requiredContainers) - reservedContainers) > 0);
   }
 
-  private Resource assignContainersOnNode(Resource clusterResource, 
+  private CSAssignment assignContainersOnNode(Resource clusterResource, 
       SchedulerNode node, SchedulerApp application, 
       Priority priority, RMContainer reservedContainer) {
 
@@ -977,7 +981,7 @@ public class LeafQueue implements CSQueue {
         assignNodeLocalContainers(clusterResource, node, application, priority,
             reservedContainer); 
     if (Resources.greaterThan(assigned, Resources.none())) {
-      return assigned;
+      return new CSAssignment(assigned, NodeType.NODE_LOCAL);
     }
 
     // Rack-local
@@ -985,12 +989,14 @@ public class LeafQueue implements CSQueue {
         assignRackLocalContainers(clusterResource, node, application, priority, 
             reservedContainer);
     if (Resources.greaterThan(assigned, Resources.none())) {
-      return assigned;
+      return new CSAssignment(assigned, NodeType.RACK_LOCAL);
     }
     
     // Off-switch
-    return assignOffSwitchContainers(clusterResource, node, application, 
-        priority, reservedContainer);
+    return new CSAssignment(
+        assignOffSwitchContainers(clusterResource, node, application, 
+            priority, reservedContainer), 
+        NodeType.OFF_SWITCH);
   }
 
   private Resource assignNodeLocalContainers(Resource clusterResource, 
@@ -1272,7 +1278,7 @@ public class LeafQueue implements CSQueue {
     metrics.setAvailableResourcesToUser(userName, application.getHeadroom());
     LOG.info(getQueueName() + 
         " used=" + usedResources + " numContainers=" + numContainers + 
-        " user=" + userName + " resources=" + user.getConsumedResources());
+        " user=" + userName + " user-resources=" + user.getConsumedResources());
   }
 
   synchronized void releaseResource(Resource clusterResource, 
@@ -1290,7 +1296,7 @@ public class LeafQueue implements CSQueue {
       
     LOG.info(getQueueName() + 
         " used=" + usedResources + " numContainers=" + numContainers + 
-        " user=" + userName + " resources=" + user.getConsumedResources());
+        " user=" + userName + " user-resources=" + user.getConsumedResources());
   }
 
   @Override

hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/ParentQueue.java

@@ -48,6 +48,7 @@ import org.apache.hadoop.yarn.factory.providers.RecordFactoryProvider;
 import org.apache.hadoop.yarn.server.resourcemanager.resource.Resources;
 import org.apache.hadoop.yarn.server.resourcemanager.rmcontainer.RMContainer;
 import org.apache.hadoop.yarn.server.resourcemanager.rmcontainer.RMContainerEventType;
+import org.apache.hadoop.yarn.server.resourcemanager.scheduler.NodeType;
 import org.apache.hadoop.yarn.server.resourcemanager.scheduler.QueueMetrics;
 import org.apache.hadoop.yarn.server.resourcemanager.scheduler.SchedulerApp;
 import org.apache.hadoop.yarn.server.resourcemanager.scheduler.SchedulerNode;
@@ -500,10 +501,12 @@ public class ParentQueue implements CSQueue {
   }
 
   @Override
-  public synchronized Resource assignContainers(
+  public synchronized CSAssignment assignContainers(
       Resource clusterResource, SchedulerNode node) {
-    Resource assigned = Resources.createResource(0);
-
+    CSAssignment assignment = 
+        new CSAssignment(Resources.createResource(0), NodeType.NODE_LOCAL);
+    boolean assignedOffSwitch = false;
+    
     while (canAssign(node)) {
       if (LOG.isDebugEnabled()) {
         LOG.debug("Trying to assign containers to child-queue of "
@@ -516,16 +519,18 @@ public class ParentQueue implements CSQueue {
       }
       
       // Schedule
-      Resource assignedToChild = 
+      CSAssignment assignedToChild = 
           assignContainersToChildQueues(clusterResource, node);
+      assignedOffSwitch = (assignedToChild.getType() == NodeType.OFF_SWITCH);
       
       // Done if no child-queue assigned anything
-      if (Resources.greaterThan(assignedToChild, Resources.none())) {
+      if (Resources.greaterThan(assignedToChild.getResource(), 
+              Resources.none())) {
         // Track resource utilization for the parent-queue
-        allocateResource(clusterResource, assignedToChild);
+        allocateResource(clusterResource, assignedToChild.getResource());
         
         // Track resource utilization in this pass of the scheduler
-        Resources.addTo(assigned, assignedToChild);
+        Resources.addTo(assignment.getResource(), assignedToChild.getResource());
         
         LOG.info("assignedContainer" +
             " queue=" + getQueueName() + 
@@ -539,17 +544,26 @@ public class ParentQueue implements CSQueue {
 
       if (LOG.isDebugEnabled()) {
         LOG.debug("ParentQ=" + getQueueName()
-          + " assignedSoFarInThisIteration=" + assigned
+          + " assignedSoFarInThisIteration=" + assignment.getResource()
           + " utilization=" + getUtilization());
       }
 
       // Do not assign more than one container if this isn't the root queue
-      if (!rootQueue) {
+      // or if we've already assigned an off-switch container
+      if (rootQueue) {
+        if (assignedOffSwitch) {
+          if (LOG.isDebugEnabled()) {
+            LOG.debug("Not assigning more than one off-switch container," +
+            		" assignments so far: " + assignment);
+          }
+          break;
+        }
+      } else {
         break;
       }
     } 
     
-    return assigned;
+    return assignment;
   }
 
   private synchronized boolean assignToQueue(Resource clusterResource) {
@@ -573,9 +587,10 @@ public class ParentQueue implements CSQueue {
                                      minimumAllocation);
   }
   
-  synchronized Resource assignContainersToChildQueues(Resource cluster, 
+  synchronized CSAssignment assignContainersToChildQueues(Resource cluster, 
       SchedulerNode node) {
-    Resource assigned = Resources.createResource(0);
+    CSAssignment assignment = 
+        new CSAssignment(Resources.createResource(0), NodeType.NODE_LOCAL);
     
     printChildQueues();
 
@@ -586,25 +601,28 @@ public class ParentQueue implements CSQueue {
         LOG.debug("Trying to assign to queue: " + childQueue.getQueuePath()
           + " stats: " + childQueue);
       }
-      assigned = childQueue.assignContainers(cluster, node);
+      assignment = childQueue.assignContainers(cluster, node);
       if(LOG.isDebugEnabled()) {
-        LOG.debug("Assignedto queue: " + childQueue.getQueuePath()
-          + " stats: " + childQueue + " --> " + assigned.getMemory());
+        LOG.debug("Assigned to queue: " + childQueue.getQueuePath() +
+          " stats: " + childQueue + " --> " + 
+          assignment.getResource().getMemory() + ", " + assignment.getType());
       }
 
       // If we do assign, remove the queue and re-insert in-order to re-sort
-      if (Resources.greaterThan(assigned, Resources.none())) {
+      if (Resources.greaterThan(assignment.getResource(), Resources.none())) {
         // Remove and re-insert to sort
         iter.remove();
         LOG.info("Re-sorting queues since queue: " + childQueue.getQueuePath() + 
             " stats: " + childQueue);
         childQueues.add(childQueue);
-        printChildQueues();
+        if (LOG.isDebugEnabled()) {
+          printChildQueues();
+        }
         break;
       }
     }
     
-    return assigned;
+    return assignment;
   }
 
   String getChildQueuesToPrint() {

hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/TestLeafQueue.java

@@ -811,49 +811,56 @@ public class TestLeafQueue {
     app_0.updateResourceRequests(app_0_requests_0);
 
     // Start testing...
+    CSAssignment assignment = null;
     
     // Start with off switch, shouldn't allocate due to delay scheduling
-    a.assignContainers(clusterResource, node_2);
+    assignment = a.assignContainers(clusterResource, node_2);
     verify(app_0, never()).allocate(any(NodeType.class), eq(node_2), 
         any(Priority.class), any(ResourceRequest.class), any(Container.class));
     assertEquals(1, app_0.getSchedulingOpportunities(priority));
     assertEquals(3, app_0.getTotalRequiredResources(priority));
+    assertEquals(NodeType.NODE_LOCAL, assignment.getType()); // None->NODE_LOCAL
 
     // Another off switch, shouldn't allocate due to delay scheduling
-    a.assignContainers(clusterResource, node_2);
+    assignment = a.assignContainers(clusterResource, node_2);
     verify(app_0, never()).allocate(any(NodeType.class), eq(node_2), 
         any(Priority.class), any(ResourceRequest.class), any(Container.class));
     assertEquals(2, app_0.getSchedulingOpportunities(priority));
     assertEquals(3, app_0.getTotalRequiredResources(priority));
+    assertEquals(NodeType.NODE_LOCAL, assignment.getType()); // None->NODE_LOCAL
     
     // Another off switch, shouldn't allocate due to delay scheduling
-    a.assignContainers(clusterResource, node_2);
+    assignment = a.assignContainers(clusterResource, node_2);
     verify(app_0, never()).allocate(any(NodeType.class), eq(node_2), 
         any(Priority.class), any(ResourceRequest.class), any(Container.class));
     assertEquals(3, app_0.getSchedulingOpportunities(priority));
     assertEquals(3, app_0.getTotalRequiredResources(priority));
+    assertEquals(NodeType.NODE_LOCAL, assignment.getType()); // None->NODE_LOCAL
     
     // Another off switch, now we should allocate 
     // since missedOpportunities=3 and reqdContainers=3
-    a.assignContainers(clusterResource, node_2);
+    assignment = a.assignContainers(clusterResource, node_2);
     verify(app_0).allocate(eq(NodeType.OFF_SWITCH), eq(node_2), 
         any(Priority.class), any(ResourceRequest.class), any(Container.class));
     assertEquals(0, app_0.getSchedulingOpportunities(priority)); // should reset
     assertEquals(2, app_0.getTotalRequiredResources(priority));
+    assertEquals(NodeType.OFF_SWITCH, assignment.getType());
     
     // NODE_LOCAL - node_0
-    a.assignContainers(clusterResource, node_0);
+    assignment = a.assignContainers(clusterResource, node_0);
     verify(app_0).allocate(eq(NodeType.NODE_LOCAL), eq(node_0), 
         any(Priority.class), any(ResourceRequest.class), any(Container.class));
     assertEquals(0, app_0.getSchedulingOpportunities(priority)); // should reset
     assertEquals(1, app_0.getTotalRequiredResources(priority));
+    assertEquals(NodeType.NODE_LOCAL, assignment.getType());
     
     // NODE_LOCAL - node_1
-    a.assignContainers(clusterResource, node_1);
+    assignment = a.assignContainers(clusterResource, node_1);
     verify(app_0).allocate(eq(NodeType.NODE_LOCAL), eq(node_1), 
         any(Priority.class), any(ResourceRequest.class), any(Container.class));
     assertEquals(0, app_0.getSchedulingOpportunities(priority)); // should reset
     assertEquals(0, app_0.getTotalRequiredResources(priority));
+    assertEquals(NodeType.NODE_LOCAL, assignment.getType());
     
     // Add 1 more request to check for RACK_LOCAL
     app_0_requests_0.clear();
@@ -872,11 +879,12 @@ public class TestLeafQueue {
     String host_3 = "host_3"; // on rack_1
     SchedulerNode node_3 = TestUtils.getMockNode(host_3, rack_1, 0, 8*GB);
     
-    a.assignContainers(clusterResource, node_3);
+    assignment = a.assignContainers(clusterResource, node_3);
     verify(app_0).allocate(eq(NodeType.RACK_LOCAL), eq(node_3), 
         any(Priority.class), any(ResourceRequest.class), any(Container.class));
     assertEquals(0, app_0.getSchedulingOpportunities(priority)); // should reset
     assertEquals(0, app_0.getTotalRequiredResources(priority));
+    assertEquals(NodeType.RACK_LOCAL, assignment.getType());
   }
   
   @Test

hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/TestParentQueue.java

@@ -29,6 +29,7 @@ import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.yarn.api.records.Resource;
 import org.apache.hadoop.yarn.server.resourcemanager.RMContext;
 import org.apache.hadoop.yarn.server.resourcemanager.resource.Resources;
+import org.apache.hadoop.yarn.server.resourcemanager.scheduler.NodeType;
 import org.apache.hadoop.yarn.server.resourcemanager.scheduler.SchedulerApp;
 import org.apache.hadoop.yarn.server.resourcemanager.scheduler.SchedulerNode;
 
@@ -92,11 +93,18 @@ public class TestParentQueue {
   private void stubQueueAllocation(final CSQueue queue, 
       final Resource clusterResource, final SchedulerNode node, 
       final int allocation) {
+    stubQueueAllocation(queue, clusterResource, node, allocation, 
+        NodeType.NODE_LOCAL);
+  }
+  
+  private void stubQueueAllocation(final CSQueue queue, 
+      final Resource clusterResource, final SchedulerNode node, 
+      final int allocation, final NodeType type) {
     
     // Simulate the queue allocation
-    doAnswer(new Answer<Resource>() {
+    doAnswer(new Answer<CSAssignment>() {
       @Override
-      public Resource answer(InvocationOnMock invocation) throws Throwable {
+      public CSAssignment answer(InvocationOnMock invocation) throws Throwable {
         try {
           throw new Exception();
         } catch (Exception e) {
@@ -115,8 +123,8 @@ public class TestParentQueue {
         
         // Next call - nothing
         if (allocation > 0) {
-          doReturn(Resources.none()).when(queue).assignContainers(
-              eq(clusterResource), eq(node));
+          doReturn(new CSAssignment(Resources.none(), type)).
+            when(queue).assignContainers(eq(clusterResource), eq(node));
 
           // Mock the node's resource availability
           Resource available = node.getAvailableResource();
@@ -124,7 +132,7 @@ public class TestParentQueue {
           when(node).getAvailableResource();
         }
 
-        return allocatedResource;
+        return new CSAssignment(allocatedResource, type);
       }
     }).
     when(queue).assignContainers(eq(clusterResource), eq(node));
@@ -401,6 +409,78 @@ public class TestParentQueue {
     
   }
   
+  @Test
+  public void testOffSwitchScheduling() throws Exception {
+    // Setup queue configs
+    setupSingleLevelQueues(csConf);
+    
+    Map<String, CSQueue> queues = new HashMap<String, CSQueue>();
+    CSQueue root = 
+        CapacityScheduler.parseQueue(csContext, csConf, null, 
+            CapacitySchedulerConfiguration.ROOT, queues, queues, 
+            CapacityScheduler.queueComparator, 
+            CapacityScheduler.applicationComparator,
+            TestUtils.spyHook);
+
+    // Setup some nodes
+    final int memoryPerNode = 10;
+    final int numNodes = 2;
+    
+    SchedulerNode node_0 = 
+        TestUtils.getMockNode("host_0", DEFAULT_RACK, 0, memoryPerNode*GB);
+    SchedulerNode node_1 = 
+        TestUtils.getMockNode("host_1", DEFAULT_RACK, 0, memoryPerNode*GB);
+    
+    final Resource clusterResource = 
+        Resources.createResource(numNodes * (memoryPerNode*GB));
+    when(csContext.getNumClusterNodes()).thenReturn(numNodes);
+
+    // Start testing
+    LeafQueue a = (LeafQueue)queues.get(A);
+    LeafQueue b = (LeafQueue)queues.get(B);
+    final float delta = 0.0001f;
+    
+    // Simulate B returning a container on node_0
+    stubQueueAllocation(a, clusterResource, node_0, 0*GB, NodeType.OFF_SWITCH);
+    stubQueueAllocation(b, clusterResource, node_0, 1*GB, NodeType.OFF_SWITCH);
+    root.assignContainers(clusterResource, node_0);
+    assertEquals(0.0f, a.getUtilization(), delta);
+    assertEquals(computeQueueUtilization(b, 1*GB, clusterResource), 
+        b.getUtilization(), delta);
+    
+    // Now, A should get the scheduling opportunity since A=0G/6G, B=1G/14G
+    // also, B gets a scheduling opportunity since A allocates RACK_LOCAL
+    stubQueueAllocation(a, clusterResource, node_1, 2*GB, NodeType.RACK_LOCAL);
+    stubQueueAllocation(b, clusterResource, node_1, 1*GB, NodeType.OFF_SWITCH);
+    root.assignContainers(clusterResource, node_1);
+    InOrder allocationOrder = inOrder(a, b);
+    allocationOrder.verify(a).assignContainers(eq(clusterResource), 
+        any(SchedulerNode.class));
+    allocationOrder.verify(b).assignContainers(eq(clusterResource), 
+        any(SchedulerNode.class));
+    assertEquals(computeQueueUtilization(a, 2*GB, clusterResource), 
+        a.getUtilization(), delta);
+    assertEquals(computeQueueUtilization(b, 2*GB, clusterResource), 
+        b.getUtilization(), delta);
+    
+    // Now, B should get the scheduling opportunity 
+    // since A has 2/6G while B has 2/14G, 
+    // However, since B returns off-switch, A won't get an opportunity
+    stubQueueAllocation(a, clusterResource, node_0, 1*GB, NodeType.NODE_LOCAL);
+    stubQueueAllocation(b, clusterResource, node_0, 2*GB, NodeType.OFF_SWITCH);
+    root.assignContainers(clusterResource, node_0);
+    allocationOrder = inOrder(b, a);
+    allocationOrder.verify(b).assignContainers(eq(clusterResource), 
+        any(SchedulerNode.class));
+    allocationOrder.verify(a).assignContainers(eq(clusterResource), 
+        any(SchedulerNode.class));
+    assertEquals(computeQueueUtilization(a, 2*GB, clusterResource), 
+        a.getUtilization(), delta);
+    assertEquals(computeQueueUtilization(b, 4*GB, clusterResource), 
+        b.getUtilization(), delta);
+
+  }
+  
   @After
   public void tearDown() throws Exception {
   }