ReduceTaskRunner.java

/**
 * 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.*;

import org.apache.hadoop.mapred.TaskTracker.TaskInProgress;

/** Runs a reduce task. */
class ReduceTaskRunner extends TaskRunner {

  public ReduceTaskRunner(TaskInProgress task, TaskTracker tracker, 
                          JobConf conf, TaskTracker.RunningJob rjob
                          ) throws IOException {
    
    super(task, tracker, conf, rjob);
  }

  /** Assemble all of the map output files */
  public boolean prepare() throws IOException {
    if (!super.prepare()) {
      return false;
    }
    
    // cleanup from failures
    mapOutputFile.removeAll();
    return true;
  }
  
  
  /** Delete all of the temporary map output files. */
  public void close() throws IOException {
    LOG.info(getTask()+" done; removing files.");
    getTask().getProgress().setStatus("closed");
    mapOutputFile.removeAll();
  }
  
  @Override
  public String getChildJavaOpts(JobConf jobConf, String defaultValue) {
    String user = 
      jobConf.get(JobConf.MAPRED_REDUCE_TASK_JAVA_OPTS, 
        super.getChildJavaOpts(jobConf, 
            JobConf.DEFAULT_MAPRED_TASK_JAVA_OPTS));
    String admin = jobConf.get(TaskRunner.MAPRED_REDUCE_ADMIN_JAVA_OPTS,
        TaskRunner.DEFAULT_MAPRED_ADMIN_JAVA_OPTS);
    return user + " " + admin;
  }

  @Override
  public int getChildUlimit(JobConf jobConf) {
    return jobConf.getInt(JobConf.MAPRED_REDUCE_TASK_ULIMIT, 
                          super.getChildUlimit(jobConf));
  }

  @Override
  public String getChildEnv(JobConf jobConf) {
    return jobConf.get(JobConf.MAPRED_REDUCE_TASK_ENV, 
                       super.getChildEnv(jobConf));
  }

}