MAPREDUCE-6353. Divide by zero error in MR AM when calculating available containers. (Anubhav Dhoot via kasha)

(cherry picked from commit 1773aac780)

hadoop-mapreduce-project/CHANGES.txt

@@ -150,6 +150,9 @@ Release 2.8.0 - UNRELEASED
     MAPREDUCE-6359. In RM HA setup, "Cluster" tab links populated with AM 
     hostname instead of RM. (zhaoyunjiong via junping_du)
 
+    MAPREDUCE-6353. Divide by zero error in MR AM when calculating available 
+    containers. (Anubhav Dhoot via kasha)
+
 Release 2.7.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/rm/ResourceCalculatorUtils.java

@@ -35,10 +35,13 @@ public class ResourceCalculatorUtils {
   public static int computeAvailableContainers(Resource available,
       Resource required, EnumSet<SchedulerResourceTypes> resourceTypes) {
     if (resourceTypes.contains(SchedulerResourceTypes.CPU)) {
-      return Math.min(available.getMemory() / required.getMemory(),
-        available.getVirtualCores() / required.getVirtualCores());
+      return Math.min(
+        calculateRatioOrMaxValue(available.getMemory(), required.getMemory()),
+        calculateRatioOrMaxValue(available.getVirtualCores(), required
+            .getVirtualCores()));
     }
-    return available.getMemory() / required.getMemory();
+    return calculateRatioOrMaxValue(
+      available.getMemory(), required.getMemory());
   }
 
   public static int divideAndCeilContainers(Resource required, Resource factor,
@@ -49,4 +52,11 @@ public class ResourceCalculatorUtils {
     }
     return divideAndCeil(required.getMemory(), factor.getMemory());
   }
+
+  private static int calculateRatioOrMaxValue(int numerator, int denominator) {
+    if (denominator == 0) {
+      return Integer.MAX_VALUE;
+    }
+    return numerator / denominator;
+  }
 }

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/test/java/org/apache/hadoop/mapreduce/v2/app/rm/TestResourceCalculatorUtils.java

@@ -0,0 +1,75 @@
+/**
+ * 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.mapreduce.v2.app.rm;
+
+import org.apache.hadoop.yarn.api.records.Resource;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.EnumSet;
+
+import static org.apache.hadoop.yarn.proto.YarnServiceProtos.*;
+
+public class TestResourceCalculatorUtils {
+  @Test
+  public void testComputeAvailableContainers() throws Exception {
+    Resource clusterAvailableResources = Resource.newInstance(81920, 40);
+
+    Resource nonZeroResource = Resource.newInstance(1024, 2);
+
+    int expectedNumberOfContainersForMemory = 80;
+    int expectedNumberOfContainersForCPU = 20;
+
+    verifyDifferentResourceTypes(clusterAvailableResources, nonZeroResource,
+        expectedNumberOfContainersForMemory,
+        expectedNumberOfContainersForCPU);
+
+    Resource zeroMemoryResource = Resource.newInstance(0,
+        nonZeroResource.getVirtualCores());
+
+    verifyDifferentResourceTypes(clusterAvailableResources, zeroMemoryResource,
+        Integer.MAX_VALUE,
+        expectedNumberOfContainersForCPU);
+
+    Resource zeroCpuResource = Resource.newInstance(nonZeroResource.getMemory(),
+        0);
+
+    verifyDifferentResourceTypes(clusterAvailableResources, zeroCpuResource,
+        expectedNumberOfContainersForMemory,
+        expectedNumberOfContainersForMemory);
+  }
+
+  private void verifyDifferentResourceTypes(Resource clusterAvailableResources,
+      Resource nonZeroResource, int expectedNumberOfContainersForMemoryOnly,
+      int expectedNumberOfContainersOverall) {
+
+    Assert.assertEquals("Incorrect number of available containers for Memory",
+        expectedNumberOfContainersForMemoryOnly,
+        ResourceCalculatorUtils.computeAvailableContainers(
+            clusterAvailableResources, nonZeroResource,
+            EnumSet.of(SchedulerResourceTypes.MEMORY)));
+
+    Assert.assertEquals("Incorrect number of available containers overall",
+        expectedNumberOfContainersOverall,
+        ResourceCalculatorUtils.computeAvailableContainers(
+            clusterAvailableResources, nonZeroResource,
+            EnumSet.of(SchedulerResourceTypes.CPU,
+                SchedulerResourceTypes.MEMORY)));
+  }
+}