/** * 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 java.io.IOException; import java.util.Collection; import java.util.List; import org.apache.hadoop.conf.Configurable; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.mapreduce.server.jobtracker.TaskTracker; /** * Used by a {@link JobTracker} to schedule {@link Task}s on * {@link TaskTracker}s. *
* {@link TaskScheduler}s typically use one or more * {@link JobInProgressListener}s to receive notifications about jobs. *
* It is the responsibility of the {@link TaskScheduler}
* to initialize tasks for a job, by calling {@link JobInProgress#initTasks()}
* between the job being added (when
* {@link JobInProgressListener#jobAdded(JobInProgress)} is called)
* and tasks for that job being assigned (by
* {@link #assignTasks(TaskTracker)}).
* @see EagerTaskInitializationListener
*/
abstract class TaskScheduler implements Configurable {
protected Configuration conf;
protected TaskTrackerManager taskTrackerManager;
public Configuration getConf() {
return conf;
}
public void setConf(Configuration conf) {
this.conf = conf;
}
public synchronized void setTaskTrackerManager(
TaskTrackerManager taskTrackerManager) {
this.taskTrackerManager = taskTrackerManager;
}
/**
* Lifecycle method to allow the scheduler to start any work in separate
* threads.
* @throws IOException
*/
public void start() throws IOException {
// do nothing
}
/**
* Lifecycle method to allow the scheduler to stop any work it is doing.
* @throws IOException
*/
public void terminate() throws IOException {
// do nothing
}
/**
* Returns the tasks we'd like the TaskTracker to execute right now.
*
* @param taskTracker The TaskTracker for which we're looking for tasks.
* @return A list of tasks to run on that TaskTracker, possibly empty.
*/
public abstract List
*
*
* @param newRootQueues
*/
abstract void refreshQueues(List