| /** |
| * 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.mapred; |
| |
| import org.apache.hadoop.mapreduce.TaskType; |
| import org.apache.hadoop.conf.Configuration; |
| |
| /** |
| * A {@link LoadManager} for use by the {@link FairScheduler} that allocates |
| * tasks evenly across nodes up to their per-node maximum, using the default |
| * load management algorithm in Hadoop. |
| */ |
| public class CapBasedLoadManager extends LoadManager { |
| |
| float maxDiff = 0.0f; |
| |
| public void setConf(Configuration conf) { |
| super.setConf(conf); |
| maxDiff = conf.getFloat("mapred.fairscheduler.load.max.diff", 0.0f); |
| } |
| |
| /** |
| * Determine how many tasks of a given type we want to run on a TaskTracker. |
| * This cap is chosen based on how many tasks of that type are outstanding in |
| * total, so that when the cluster is used below capacity, tasks are spread |
| * out uniformly across the nodes rather than being clumped up on whichever |
| * machines sent out heartbeats earliest. |
| */ |
| int getCap(int totalRunnableTasks, int localMaxTasks, int totalSlots) { |
| double load = maxDiff + ((double)totalRunnableTasks) / totalSlots; |
| return (int) Math.ceil(localMaxTasks * Math.min(1.0, load)); |
| } |
| |
| @Override |
| public boolean canAssignMap(TaskTrackerStatus tracker, |
| int totalRunnableMaps, int totalMapSlots) { |
| return tracker.countMapTasks() < getCap(totalRunnableMaps, |
| tracker.getMaxMapSlots(), totalMapSlots); |
| } |
| |
| @Override |
| public boolean canAssignReduce(TaskTrackerStatus tracker, |
| int totalRunnableReduces, int totalReduceSlots) { |
| return tracker.countReduceTasks() < getCap(totalRunnableReduces, |
| tracker.getMaxReduceSlots(), totalReduceSlots); |
| } |
| |
| @Override |
| public boolean canLaunchTask(TaskTrackerStatus tracker, |
| JobInProgress job, TaskType type) { |
| return true; |
| } |
| } |