/**
* 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;
/**
* A {@link TaskSelector} implementation that wraps around the default
* {@link JobInProgress#obtainNewMapTask(TaskTrackerStatus, int)} and
* {@link JobInProgress#obtainNewReduceTask(TaskTrackerStatus, int)} methods
* in {@link JobInProgress}, using the default Hadoop locality and speculative
* threshold algorithms.
*/
public class DefaultTaskSelector extends TaskSelector {
@Override
public int neededSpeculativeMaps(JobInProgress job) {
return job.neededSpeculativeMaps();
}
@Override
public int neededSpeculativeReduces(JobInProgress job) {
return job.neededSpeculativeReduces();
}
@Override
public Task obtainNewMapTask(TaskTrackerStatus taskTracker, JobInProgress job)
throws IOException {
ClusterStatus clusterStatus = taskTrackerManager.getClusterStatus();
int numTaskTrackers = clusterStatus.getTaskTrackers();
return job.obtainNewMapTask(taskTracker, numTaskTrackers,
taskTrackerManager.getNumberOfUniqueHosts());
}
@Override
public Task obtainNewReduceTask(TaskTrackerStatus taskTracker, JobInProgress job)
throws IOException {
ClusterStatus clusterStatus = taskTrackerManager.getClusterStatus();
int numTaskTrackers = clusterStatus.getTaskTrackers();
return job.obtainNewReduceTask(taskTracker, numTaskTrackers,
taskTrackerManager.getNumberOfUniqueHosts());
}
}