DefaultTaskSelector.java
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上传日期:2018-01-08
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- /**
- * 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) {
- int count = 0;
- long time = System.currentTimeMillis();
- double avgProgress = job.getStatus().mapProgress();
- for (TaskInProgress tip: job.maps) {
- if (tip.isRunning() && tip.hasSpeculativeTask(time, avgProgress)) {
- count++;
- }
- }
- return count;
- }
- @Override
- public int neededSpeculativeReduces(JobInProgress job) {
- int count = 0;
- long time = System.currentTimeMillis();
- double avgProgress = job.getStatus().reduceProgress();
- for (TaskInProgress tip: job.reduces) {
- if (tip.isRunning() && tip.hasSpeculativeTask(time, avgProgress)) {
- count++;
- }
- }
- return count;
- }
- @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());
- }
- }