hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/TestFairSchedulerPreemption.java - hadoop - Git at Google

 /**
  * 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.fair;

 import org.apache.hadoop.yarn.api.records.ApplicationAttemptId;
 import org.apache.hadoop.yarn.server.resourcemanager.MockRM;
 import org.apache.hadoop.yarn.server.resourcemanager.rmnode.RMNode;
 import org.apache.hadoop.yarn.server.resourcemanager.scheduler.event.NodeUpdateSchedulerEvent;
 import org.apache.hadoop.yarn.server.resourcemanager.rmcontainer.RMContainer;
 import org.apache.hadoop.yarn.server.resourcemanager.rmcontainer.RMContainerImpl;
 import org.apache.hadoop.yarn.util.ControlledClock;
 import org.apache.hadoop.yarn.util.SystemClock;
 import org.junit.After;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.Parameterized;

 import java.io.File;
 import java.io.FileWriter;
 import java.io.IOException;
 import java.io.PrintWriter;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.List;

 /**
  * Tests to verify fairshare and minshare preemption, using parameterization.
  */
 @RunWith(Parameterized.class)
 public class TestFairSchedulerPreemption extends FairSchedulerTestBase {
   private static final File ALLOC_FILE = new File(TEST_DIR, "test-queues");
   private static final int GB = 1024;

   // Scheduler clock
   private final ControlledClock clock = new ControlledClock();

   // Node Capacity = NODE_CAPACITY_MULTIPLE * (1 GB or 1 vcore)
   private static final int NODE_CAPACITY_MULTIPLE = 4;

   private final boolean fairsharePreemption;
   private final boolean drf;

   // App that takes up the entire cluster
   private FSAppAttempt greedyApp;

   // Starving app that is expected to instigate preemption
   private FSAppAttempt starvingApp;

   @Parameterized.Parameters(name = "{0}")
   public static Collection<Object[]> getParameters() {
     return Arrays.asList(new Object[][] {
         {"MinSharePreemption", 0},
         {"MinSharePreemptionWithDRF", 1},
         {"FairSharePreemption", 2},
         {"FairSharePreemptionWithDRF", 3}
     });
   }

   public TestFairSchedulerPreemption(String name, int mode)
       throws IOException {
     fairsharePreemption = (mode > 1); // 2 and 3
     drf = (mode % 2 == 1); // 1 and 3
     writeAllocFile();
   }

   @Before
   public void setup() throws IOException {
     createConfiguration();
     conf.set(FairSchedulerConfiguration.ALLOCATION_FILE,
         ALLOC_FILE.getAbsolutePath());
     conf.setBoolean(FairSchedulerConfiguration.PREEMPTION, true);
     conf.setFloat(FairSchedulerConfiguration.PREEMPTION_THRESHOLD, 0f);
     conf.setInt(FairSchedulerConfiguration.WAIT_TIME_BEFORE_KILL, 0);
     setupCluster();
   }

   @After
   public void teardown() {
     ALLOC_FILE.delete();
     conf = null;
     if (resourceManager != null) {
       resourceManager.stop();
       resourceManager = null;
     }
   }

   private void writeAllocFile() throws IOException {
     /*
      * Queue hierarchy:
      * root
      * |--- preemptable
      *      |--- child-1
      *      |--- child-2
      * |--- preemptable-sibling
      * |--- nonpreemptible
      *      |--- child-1
      *      |--- child-2
      */
     PrintWriter out = new PrintWriter(new FileWriter(ALLOC_FILE));
     out.println("<?xml version=\"1.0\"?>");
     out.println("<allocations>");

     out.println("<queue name=\"preemptable\">");
     writePreemptionParams(out);

     // Child-1
     out.println("<queue name=\"child-1\">");
     writeResourceParams(out);
     out.println("</queue>");

     // Child-2
     out.println("<queue name=\"child-2\">");
     writeResourceParams(out);
     out.println("</queue>");

     out.println("</queue>"); // end of preemptable queue

     out.println("<queue name=\"preemptable-sibling\">");
     writePreemptionParams(out);
     out.println("</queue>");

     // Queue with preemption disallowed
     out.println("<queue name=\"nonpreemptable\">");
     out.println("<allowPreemptionFrom>false" +
         "</allowPreemptionFrom>");
     writePreemptionParams(out);

     // Child-1
     out.println("<queue name=\"child-1\">");
     writeResourceParams(out);
     out.println("</queue>");

     // Child-2
     out.println("<queue name=\"child-2\">");
     writeResourceParams(out);
     out.println("</queue>");

     out.println("</queue>"); // end of nonpreemptable queue

     if (drf) {
       out.println("<defaultQueueSchedulingPolicy>drf" +
           "</defaultQueueSchedulingPolicy>");
     }
     out.println("</allocations>");
     out.close();

     assertTrue("Allocation file does not exist, not running the test",
         ALLOC_FILE.exists());
   }

   private void writePreemptionParams(PrintWriter out) {
     if (fairsharePreemption) {
       out.println("<fairSharePreemptionThreshold>1" +
           "</fairSharePreemptionThreshold>");
       out.println("<fairSharePreemptionTimeout>0" +
           "</fairSharePreemptionTimeout>");
     } else {
       out.println("<minSharePreemptionTimeout>0" +
           "</minSharePreemptionTimeout>");
     }
   }

   private void writeResourceParams(PrintWriter out) {
     if (!fairsharePreemption) {
       out.println("<minResources>4096mb,4vcores</minResources>");
     }
   }

   private void setupCluster() throws IOException {
     resourceManager = new MockRM(conf);
     scheduler = (FairScheduler) resourceManager.getResourceScheduler();
     // YARN-6249, FSLeafQueue#lastTimeAtMinShare is initialized to the time in
     // the real world, so we should keep the clock up with it.
     clock.setTime(SystemClock.getInstance().getTime());
     scheduler.setClock(clock);
     resourceManager.start();

     // Create and add two nodes to the cluster, with capacities
     // disproportional to the container requests.
     addNode(NODE_CAPACITY_MULTIPLE * GB, 3 * NODE_CAPACITY_MULTIPLE);
     addNode(NODE_CAPACITY_MULTIPLE * GB, 3 * NODE_CAPACITY_MULTIPLE);

     // Reinitialize the scheduler so DRF policy picks up cluster capacity
     // TODO (YARN-6194): One shouldn't need to call this
     scheduler.reinitialize(conf, resourceManager.getRMContext());

     // Verify if child-1 and child-2 are preemptable
     FSQueue child1 =
         scheduler.getQueueManager().getQueue("nonpreemptable.child-1");
     assertFalse(child1.isPreemptable());
     FSQueue child2 =
         scheduler.getQueueManager().getQueue("nonpreemptable.child-2");
     assertFalse(child2.isPreemptable());
   }

   private void sendEnoughNodeUpdatesToAssignFully() {
     for (RMNode node : rmNodes) {
       NodeUpdateSchedulerEvent nodeUpdateSchedulerEvent =
           new NodeUpdateSchedulerEvent(node);
       for (int i = 0; i < NODE_CAPACITY_MULTIPLE; i++) {
         scheduler.handle(nodeUpdateSchedulerEvent);
       }
     }
   }

   /**
    * Submit an application to a given queue and take over the entire cluster.
    *
    * @param queueName queue name
    */
   private void takeAllResources(String queueName) {
     // Create an app that takes up all the resources on the cluster
     ApplicationAttemptId appAttemptId
         = createSchedulingRequest(GB, 1, queueName, "default",
         NODE_CAPACITY_MULTIPLE * rmNodes.size());
     greedyApp = scheduler.getSchedulerApp(appAttemptId);
     scheduler.update();
     sendEnoughNodeUpdatesToAssignFully();
     assertEquals(8, greedyApp.getLiveContainers().size());
     // Verify preemptable for queue and app attempt
     assertTrue(
         scheduler.getQueueManager().getQueue(queueName).isPreemptable()
             == greedyApp.isPreemptable());
   }

   /**
    * Submit an application to a given queue and preempt half resources of the
    * cluster.
    *
    * @param queueName queue name
    * @throws InterruptedException
    *         if any thread has interrupted the current thread.
    */
   private void preemptHalfResources(String queueName)
       throws InterruptedException {
     ApplicationAttemptId appAttemptId
         = createSchedulingRequest(2 * GB, 2, queueName, "default",
         NODE_CAPACITY_MULTIPLE * rmNodes.size() / 2);
     starvingApp = scheduler.getSchedulerApp(appAttemptId);

     // Move clock enough to identify starvation
     clock.tickSec(1);
     scheduler.update();
   }

   /**
    * Submit application to {@code queue1} and take over the entire cluster.
    * Submit application with larger containers to {@code queue2} that
    * requires preemption from the first application.
    *
    * @param queue1 first queue
    * @param queue2 second queue
    * @throws InterruptedException if interrupted while waiting
    */
   private void submitApps(String queue1, String queue2)
       throws InterruptedException {
     takeAllResources(queue1);
     preemptHalfResources(queue2);
   }

   private void verifyPreemption(int numStarvedAppContainers)
       throws InterruptedException {
     // Sleep long enough for four containers to be preempted.
     for (int i = 0; i < 1000; i++) {
       if (greedyApp.getLiveContainers().size() == 2 * numStarvedAppContainers) {
         break;
       }
       Thread.sleep(10);
     }

     // Post preemption, verify the greedyApp has the correct # of containers.
     assertEquals("Incorrect # of containers on the greedy app",
         2 * numStarvedAppContainers, greedyApp.getLiveContainers().size());

     // Verify the queue metrics are set appropriately. The greedyApp started
     // with 8 1GB, 1vcore containers.
     assertEquals("Incorrect # of preempted containers in QueueMetrics",
         8 - 2 * numStarvedAppContainers,
         greedyApp.getQueue().getMetrics().getAggregatePreemptedContainers());

     // Verify the node is reserved for the starvingApp
     for (RMNode rmNode : rmNodes) {
       FSSchedulerNode node = (FSSchedulerNode)
           scheduler.getNodeTracker().getNode(rmNode.getNodeID());
       if (node.getContainersForPreemption().size() > 0) {
         assertTrue("node should be reserved for the starvingApp",
             node.getPreemptionList().keySet().contains(starvingApp));
       }
     }

     sendEnoughNodeUpdatesToAssignFully();

     // Verify the preempted containers are assigned to starvingApp
     assertEquals("Starved app is not assigned the right # of containers",
         numStarvedAppContainers, starvingApp.getLiveContainers().size());

     // Verify the node is not reserved for the starvingApp anymore
     for (RMNode rmNode : rmNodes) {
       FSSchedulerNode node = (FSSchedulerNode)
           scheduler.getNodeTracker().getNode(rmNode.getNodeID());
       if (node.getContainersForPreemption().size() > 0) {
         assertFalse(node.getPreemptionList().keySet().contains(starvingApp));
       }
     }
   }

   private void verifyNoPreemption() throws InterruptedException {
     // Sleep long enough to ensure not even one container is preempted.
     for (int i = 0; i < 100; i++) {
       if (greedyApp.getLiveContainers().size() != 8) {
         break;
       }
       Thread.sleep(10);
     }
     assertEquals(8, greedyApp.getLiveContainers().size());
   }

   @Test
   public void testPreemptionWithinSameLeafQueue() throws Exception {
     String queue = "root.preemptable.child-1";
     submitApps(queue, queue);
     if (fairsharePreemption) {
       verifyPreemption(2);
     } else {
       verifyNoPreemption();
     }
   }

   @Test
   public void testPreemptionBetweenTwoSiblingLeafQueues() throws Exception {
     submitApps("root.preemptable.child-1", "root.preemptable.child-2");
     verifyPreemption(2);
   }

   @Test
   public void testPreemptionBetweenNonSiblingQueues() throws Exception {
     submitApps("root.preemptable.child-1", "root.nonpreemptable.child-1");
     verifyPreemption(2);
   }

   @Test
   public void testNoPreemptionFromDisallowedQueue() throws Exception {
     submitApps("root.nonpreemptable.child-1", "root.preemptable.child-1");
     verifyNoPreemption();
   }

   /**
    * Set the number of AM containers for each node.
    *
    * @param numAMContainersPerNode number of AM containers per node
    */
   private void setNumAMContainersPerNode(int numAMContainersPerNode) {
     List<FSSchedulerNode> potentialNodes =
         scheduler.getNodeTracker().getNodesByResourceName("*");
     for (FSSchedulerNode node: potentialNodes) {
       List<RMContainer> containers=
           node.getCopiedListOfRunningContainers();
       // Change the first numAMContainersPerNode out of 4 containers to
       // AM containers
       for (int i = 0; i < numAMContainersPerNode; i++) {
         ((RMContainerImpl) containers.get(i)).setAMContainer(true);
       }
     }
   }

   @Test
   public void testPreemptionSelectNonAMContainer() throws Exception {
     takeAllResources("root.preemptable.child-1");
     setNumAMContainersPerNode(2);
     preemptHalfResources("root.preemptable.child-2");

     verifyPreemption(2);

     ArrayList<RMContainer> containers =
         (ArrayList<RMContainer>) starvingApp.getLiveContainers();
     String host0 = containers.get(0).getNodeId().getHost();
     String host1 = containers.get(1).getNodeId().getHost();
     // Each node provides two and only two non-AM containers to be preempted, so
     // the preemption happens on both nodes.
     assertTrue("Preempted containers should come from two different "
         + "nodes.", !host0.equals(host1));
   }

   @Test
   public void testPreemptionBetweenSiblingQueuesWithParentAtFairShare()
       throws InterruptedException {
     // Run this test only for fairshare preemption
     if (!fairsharePreemption) {
       return;
     }

     // Let one of the child queues take over the entire cluster
     takeAllResources("root.preemptable.child-1");

     // Submit a job so half the resources go to parent's sibling
     preemptHalfResources("root.preemptable-sibling");
     verifyPreemption(2);

     // Submit a job to the child's sibling to force preemption from the child
     preemptHalfResources("root.preemptable.child-2");
     verifyPreemption(1);
   }
 }
	/**
	* 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.fair;

	import org.apache.hadoop.yarn.api.records.ApplicationAttemptId;
	import org.apache.hadoop.yarn.server.resourcemanager.MockRM;
	import org.apache.hadoop.yarn.server.resourcemanager.rmnode.RMNode;
	import org.apache.hadoop.yarn.server.resourcemanager.scheduler.event.NodeUpdateSchedulerEvent;
	import org.apache.hadoop.yarn.server.resourcemanager.rmcontainer.RMContainer;
	import org.apache.hadoop.yarn.server.resourcemanager.rmcontainer.RMContainerImpl;
	import org.apache.hadoop.yarn.util.ControlledClock;
	import org.apache.hadoop.yarn.util.SystemClock;
	import org.junit.After;
	import static org.junit.Assert.assertEquals;
	import static org.junit.Assert.assertFalse;
	import static org.junit.Assert.assertTrue;
	import org.junit.Before;
	import org.junit.Test;
	import org.junit.runner.RunWith;
	import org.junit.runners.Parameterized;

	import java.io.File;
	import java.io.FileWriter;
	import java.io.IOException;
	import java.io.PrintWriter;
	import java.util.ArrayList;
	import java.util.Arrays;
	import java.util.Collection;
	import java.util.List;

	/**
	* Tests to verify fairshare and minshare preemption, using parameterization.
	*/
	@RunWith(Parameterized.class)
	public class TestFairSchedulerPreemption extends FairSchedulerTestBase {
	private static final File ALLOC_FILE = new File(TEST_DIR, "test-queues");
	private static final int GB = 1024;

	// Scheduler clock
	private final ControlledClock clock = new ControlledClock();

	// Node Capacity = NODE_CAPACITY_MULTIPLE * (1 GB or 1 vcore)
	private static final int NODE_CAPACITY_MULTIPLE = 4;

	private final boolean fairsharePreemption;
	private final boolean drf;

	// App that takes up the entire cluster
	private FSAppAttempt greedyApp;

	// Starving app that is expected to instigate preemption
	private FSAppAttempt starvingApp;

	@Parameterized.Parameters(name = "{0}")
	public static Collection<Object[]> getParameters() {
	return Arrays.asList(new Object[][] {
	{"MinSharePreemption", 0},
	{"MinSharePreemptionWithDRF", 1},
	{"FairSharePreemption", 2},
	{"FairSharePreemptionWithDRF", 3}
	});
	}

	public TestFairSchedulerPreemption(String name, int mode)
	throws IOException {
	fairsharePreemption = (mode > 1); // 2 and 3
	drf = (mode % 2 == 1); // 1 and 3
	writeAllocFile();
	}

	@Before
	public void setup() throws IOException {
	createConfiguration();
	conf.set(FairSchedulerConfiguration.ALLOCATION_FILE,
	ALLOC_FILE.getAbsolutePath());
	conf.setBoolean(FairSchedulerConfiguration.PREEMPTION, true);
	conf.setFloat(FairSchedulerConfiguration.PREEMPTION_THRESHOLD, 0f);
	conf.setInt(FairSchedulerConfiguration.WAIT_TIME_BEFORE_KILL, 0);
	setupCluster();
	}

	@After
	public void teardown() {
	ALLOC_FILE.delete();
	conf = null;
	if (resourceManager != null) {
	resourceManager.stop();
	resourceManager = null;
	}
	}

	private void writeAllocFile() throws IOException {
	/*
	* Queue hierarchy:
	* root
	* \|--- preemptable
	* \|--- child-1
	* \|--- child-2
	* \|--- preemptable-sibling
	* \|--- nonpreemptible
	* \|--- child-1
	* \|--- child-2
	*/
	PrintWriter out = new PrintWriter(new FileWriter(ALLOC_FILE));
	out.println("<?xml version=\"1.0\"?>");
	out.println("<allocations>");

	out.println("<queue name=\"preemptable\">");
	writePreemptionParams(out);

	// Child-1
	out.println("<queue name=\"child-1\">");
	writeResourceParams(out);
	out.println("</queue>");

	// Child-2
	out.println("<queue name=\"child-2\">");
	writeResourceParams(out);
	out.println("</queue>");

	out.println("</queue>"); // end of preemptable queue

	out.println("<queue name=\"preemptable-sibling\">");
	writePreemptionParams(out);
	out.println("</queue>");

	// Queue with preemption disallowed
	out.println("<queue name=\"nonpreemptable\">");
	out.println("<allowPreemptionFrom>false" +
	"</allowPreemptionFrom>");
	writePreemptionParams(out);

	// Child-1
	out.println("<queue name=\"child-1\">");
	writeResourceParams(out);
	out.println("</queue>");

	// Child-2
	out.println("<queue name=\"child-2\">");
	writeResourceParams(out);
	out.println("</queue>");

	out.println("</queue>"); // end of nonpreemptable queue

	if (drf) {
	out.println("<defaultQueueSchedulingPolicy>drf" +
	"</defaultQueueSchedulingPolicy>");
	}
	out.println("</allocations>");
	out.close();

	assertTrue("Allocation file does not exist, not running the test",
	ALLOC_FILE.exists());
	}

	private void writePreemptionParams(PrintWriter out) {
	if (fairsharePreemption) {
	out.println("<fairSharePreemptionThreshold>1" +
	"</fairSharePreemptionThreshold>");
	out.println("<fairSharePreemptionTimeout>0" +
	"</fairSharePreemptionTimeout>");
	} else {
	out.println("<minSharePreemptionTimeout>0" +
	"</minSharePreemptionTimeout>");
	}
	}

	private void writeResourceParams(PrintWriter out) {
	if (!fairsharePreemption) {
	out.println("<minResources>4096mb,4vcores</minResources>");
	}
	}

	private void setupCluster() throws IOException {
	resourceManager = new MockRM(conf);
	scheduler = (FairScheduler) resourceManager.getResourceScheduler();
	// YARN-6249, FSLeafQueue#lastTimeAtMinShare is initialized to the time in
	// the real world, so we should keep the clock up with it.
	clock.setTime(SystemClock.getInstance().getTime());
	scheduler.setClock(clock);
	resourceManager.start();

	// Create and add two nodes to the cluster, with capacities
	// disproportional to the container requests.
	addNode(NODE_CAPACITY_MULTIPLE * GB, 3 * NODE_CAPACITY_MULTIPLE);
	addNode(NODE_CAPACITY_MULTIPLE * GB, 3 * NODE_CAPACITY_MULTIPLE);

	// Reinitialize the scheduler so DRF policy picks up cluster capacity
	// TODO (YARN-6194): One shouldn't need to call this
	scheduler.reinitialize(conf, resourceManager.getRMContext());

	// Verify if child-1 and child-2 are preemptable
	FSQueue child1 =
	scheduler.getQueueManager().getQueue("nonpreemptable.child-1");
	assertFalse(child1.isPreemptable());
	FSQueue child2 =
	scheduler.getQueueManager().getQueue("nonpreemptable.child-2");
	assertFalse(child2.isPreemptable());
	}

	private void sendEnoughNodeUpdatesToAssignFully() {
	for (RMNode node : rmNodes) {
	NodeUpdateSchedulerEvent nodeUpdateSchedulerEvent =
	new NodeUpdateSchedulerEvent(node);
	for (int i = 0; i < NODE_CAPACITY_MULTIPLE; i++) {
	scheduler.handle(nodeUpdateSchedulerEvent);
	}
	}
	}

	/**
	* Submit an application to a given queue and take over the entire cluster.
	*
	* @param queueName queue name
	*/
	private void takeAllResources(String queueName) {
	// Create an app that takes up all the resources on the cluster
	ApplicationAttemptId appAttemptId
	= createSchedulingRequest(GB, 1, queueName, "default",
	NODE_CAPACITY_MULTIPLE * rmNodes.size());
	greedyApp = scheduler.getSchedulerApp(appAttemptId);
	scheduler.update();
	sendEnoughNodeUpdatesToAssignFully();
	assertEquals(8, greedyApp.getLiveContainers().size());
	// Verify preemptable for queue and app attempt
	assertTrue(
	scheduler.getQueueManager().getQueue(queueName).isPreemptable()
	== greedyApp.isPreemptable());
	}

	/**
	* Submit an application to a given queue and preempt half resources of the
	* cluster.
	*
	* @param queueName queue name
	* @throws InterruptedException
	* if any thread has interrupted the current thread.
	*/
	private void preemptHalfResources(String queueName)
	throws InterruptedException {
	ApplicationAttemptId appAttemptId
	= createSchedulingRequest(2 * GB, 2, queueName, "default",
	NODE_CAPACITY_MULTIPLE * rmNodes.size() / 2);
	starvingApp = scheduler.getSchedulerApp(appAttemptId);

	// Move clock enough to identify starvation
	clock.tickSec(1);
	scheduler.update();
	}

	/**
	* Submit application to {@code queue1} and take over the entire cluster.
	* Submit application with larger containers to {@code queue2} that
	* requires preemption from the first application.
	*
	* @param queue1 first queue
	* @param queue2 second queue
	* @throws InterruptedException if interrupted while waiting
	*/
	private void submitApps(String queue1, String queue2)
	throws InterruptedException {
	takeAllResources(queue1);
	preemptHalfResources(queue2);
	}

	private void verifyPreemption(int numStarvedAppContainers)
	throws InterruptedException {
	// Sleep long enough for four containers to be preempted.
	for (int i = 0; i < 1000; i++) {
	if (greedyApp.getLiveContainers().size() == 2 * numStarvedAppContainers) {
	break;
	}
	Thread.sleep(10);
	}

	// Post preemption, verify the greedyApp has the correct # of containers.
	assertEquals("Incorrect # of containers on the greedy app",
	2 * numStarvedAppContainers, greedyApp.getLiveContainers().size());

	// Verify the queue metrics are set appropriately. The greedyApp started
	// with 8 1GB, 1vcore containers.
	assertEquals("Incorrect # of preempted containers in QueueMetrics",
	8 - 2 * numStarvedAppContainers,
	greedyApp.getQueue().getMetrics().getAggregatePreemptedContainers());

	// Verify the node is reserved for the starvingApp
	for (RMNode rmNode : rmNodes) {
	FSSchedulerNode node = (FSSchedulerNode)
	scheduler.getNodeTracker().getNode(rmNode.getNodeID());
	if (node.getContainersForPreemption().size() > 0) {
	assertTrue("node should be reserved for the starvingApp",
	node.getPreemptionList().keySet().contains(starvingApp));
	}
	}

	sendEnoughNodeUpdatesToAssignFully();

	// Verify the preempted containers are assigned to starvingApp
	assertEquals("Starved app is not assigned the right # of containers",
	numStarvedAppContainers, starvingApp.getLiveContainers().size());

	// Verify the node is not reserved for the starvingApp anymore
	for (RMNode rmNode : rmNodes) {
	FSSchedulerNode node = (FSSchedulerNode)
	scheduler.getNodeTracker().getNode(rmNode.getNodeID());
	if (node.getContainersForPreemption().size() > 0) {
	assertFalse(node.getPreemptionList().keySet().contains(starvingApp));
	}
	}
	}

	private void verifyNoPreemption() throws InterruptedException {
	// Sleep long enough to ensure not even one container is preempted.
	for (int i = 0; i < 100; i++) {
	if (greedyApp.getLiveContainers().size() != 8) {
	break;
	}
	Thread.sleep(10);
	}
	assertEquals(8, greedyApp.getLiveContainers().size());
	}

	@Test
	public void testPreemptionWithinSameLeafQueue() throws Exception {
	String queue = "root.preemptable.child-1";
	submitApps(queue, queue);
	if (fairsharePreemption) {
	verifyPreemption(2);
	} else {
	verifyNoPreemption();
	}
	}

	@Test
	public void testPreemptionBetweenTwoSiblingLeafQueues() throws Exception {
	submitApps("root.preemptable.child-1", "root.preemptable.child-2");
	verifyPreemption(2);
	}

	@Test
	public void testPreemptionBetweenNonSiblingQueues() throws Exception {
	submitApps("root.preemptable.child-1", "root.nonpreemptable.child-1");
	verifyPreemption(2);
	}

	@Test
	public void testNoPreemptionFromDisallowedQueue() throws Exception {
	submitApps("root.nonpreemptable.child-1", "root.preemptable.child-1");
	verifyNoPreemption();
	}

	/**
	* Set the number of AM containers for each node.
	*
	* @param numAMContainersPerNode number of AM containers per node
	*/
	private void setNumAMContainersPerNode(int numAMContainersPerNode) {
	List<FSSchedulerNode> potentialNodes =
	scheduler.getNodeTracker().getNodesByResourceName("*");
	for (FSSchedulerNode node: potentialNodes) {
	List<RMContainer> containers=
	node.getCopiedListOfRunningContainers();
	// Change the first numAMContainersPerNode out of 4 containers to
	// AM containers
	for (int i = 0; i < numAMContainersPerNode; i++) {
	((RMContainerImpl) containers.get(i)).setAMContainer(true);
	}
	}
	}

	@Test
	public void testPreemptionSelectNonAMContainer() throws Exception {
	takeAllResources("root.preemptable.child-1");
	setNumAMContainersPerNode(2);
	preemptHalfResources("root.preemptable.child-2");

	verifyPreemption(2);

	ArrayList<RMContainer> containers =
	(ArrayList<RMContainer>) starvingApp.getLiveContainers();
	String host0 = containers.get(0).getNodeId().getHost();
	String host1 = containers.get(1).getNodeId().getHost();
	// Each node provides two and only two non-AM containers to be preempted, so
	// the preemption happens on both nodes.
	assertTrue("Preempted containers should come from two different "
	+ "nodes.", !host0.equals(host1));
	}

	@Test
	public void testPreemptionBetweenSiblingQueuesWithParentAtFairShare()
	throws InterruptedException {
	// Run this test only for fairshare preemption
	if (!fairsharePreemption) {
	return;
	}

	// Let one of the child queues take over the entire cluster
	takeAllResources("root.preemptable.child-1");

	// Submit a job so half the resources go to parent's sibling
	preemptHalfResources("root.preemptable-sibling");
	verifyPreemption(2);

	// Submit a job to the child's sibling to force preemption from the child
	preemptHalfResources("root.preemptable.child-2");
	verifyPreemption(1);
	}
	}