/**
* 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.mapreduce.server.jobtracker;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.mapred.JobInProgress;
import org.apache.hadoop.mapred.JobTracker;
import org.apache.hadoop.mapred.TaskTrackerStatus;
import org.apache.hadoop.mapreduce.JobID;
import org.apache.hadoop.mapreduce.TaskType;
/**
* The representation of a single <code>TaskTracker</code> as seen by
* the {@link JobTracker}.
*/
@InterfaceAudience.LimitedPrivate("MapReduce")
@InterfaceStability.Unstable
public class TaskTracker {
static final Log LOG = LogFactory.getLog(TaskTracker.class);
final private String trackerName;
private TaskTrackerStatus status;
private JobInProgress jobForFallowMapSlot;
private JobInProgress jobForFallowReduceSlot;
/**
* Create a new {@link TaskTracker}.
* @param trackerName Unique identifier for the <code>TaskTracker</code>
*/
public TaskTracker(String trackerName) {
this.trackerName = trackerName;
}
/**
* Get the unique identifier for the {@link TaskTracker}
* @return the unique identifier for the <code>TaskTracker</code>
*/
public String getTrackerName() {
return trackerName;
}
/**
* Get the current {@link TaskTrackerStatus} of the <code>TaskTracker</code>.
* @return the current <code>TaskTrackerStatus</code> of the
* <code>TaskTracker</code>
*/
public TaskTrackerStatus getStatus() {
return status;
}
/**
* Set the current {@link TaskTrackerStatus} of the <code>TaskTracker</code>.
* @param status the current <code>TaskTrackerStatus</code> of the
* <code>TaskTracker</code>
*/
public void setStatus(TaskTrackerStatus status) {
this.status = status;
}
/**
* Get the number of currently available slots on this tasktracker for the
* given type of the task.
* @param taskType the {@link TaskType} to check for number of available slots
* @return the number of currently available slots for the given
* <code>taskType</code>
*/
public int getAvailableSlots(TaskType taskType) {
int availableSlots = 0;
if (taskType == TaskType.MAP) {
if (LOG.isDebugEnabled()) {
LOG.debug(trackerName + " getAvailSlots:" +
" max(m)=" + status.getMaxMapSlots() +
" occupied(m)=" + status.countOccupiedMapSlots());
}
availableSlots = status.getAvailableMapSlots();
} else {
if (LOG.isDebugEnabled()) {
LOG.debug(trackerName + " getAvailSlots:" +
" max(r)=" + status.getMaxReduceSlots() +
" occupied(r)=" + status.countOccupiedReduceSlots());
}
availableSlots = status.getAvailableReduceSlots();
}
return availableSlots;
}
/**
* Get the {@link JobInProgress} for which the fallow slot(s) are held.
* @param taskType {@link TaskType} of the task
* @return the task for which the fallow slot(s) are held,
* <code>null</code> if there are no fallow slots
*/
public JobInProgress getJobForFallowSlot(TaskType taskType) {
return
(taskType == TaskType.MAP) ? jobForFallowMapSlot : jobForFallowReduceSlot;
}
/**
* Reserve specified number of slots for a given <code>job</code>.
* @param taskType {@link TaskType} of the task
* @param job the job for which slots on this <code>TaskTracker</code>
* are to be reserved
* @param numSlots number of slots to be reserved
*/
public void reserveSlots(TaskType taskType, JobInProgress job, int numSlots) {
JobID jobId = job.getJobID();
if (taskType == TaskType.MAP) {
if (jobForFallowMapSlot != null &&
!jobForFallowMapSlot.getJobID().equals(jobId)) {
throw new RuntimeException(trackerName + " already has " +
"slots reserved for " +
jobForFallowMapSlot + "; being" +
" asked to reserve " + numSlots + " for " +
jobId);
}
jobForFallowMapSlot = job;
} else if (taskType == TaskType.REDUCE){
if (jobForFallowReduceSlot != null &&
!jobForFallowReduceSlot.getJobID().equals(jobId)) {
throw new RuntimeException(trackerName + " already has " +
"slots reserved for " +
jobForFallowReduceSlot + "; being" +
" asked to reserve " + numSlots + " for " +
jobId);
}
jobForFallowReduceSlot = job;
}
job.reserveTaskTracker(this, taskType, numSlots);
LOG.info(trackerName + ": Reserved " + numSlots + " " + taskType +
" slots for " + jobId);
}
/**
* Free map slots on this <code>TaskTracker</code> which were reserved for
* <code>taskType</code>.
* @param taskType {@link TaskType} of the task
* @param job job whose slots are being un-reserved
*/
public void unreserveSlots(TaskType taskType, JobInProgress job) {
JobID jobId = job.getJobID();
if (taskType == TaskType.MAP) {
if (jobForFallowMapSlot == null ||
!jobForFallowMapSlot.getJobID().equals(jobId)) {
throw new RuntimeException(trackerName + " already has " +
"slots reserved for " +
jobForFallowMapSlot + "; being" +
" asked to un-reserve for " + jobId);
}
jobForFallowMapSlot = null;
} else {
if (jobForFallowReduceSlot == null ||
!jobForFallowReduceSlot.getJobID().equals(jobId)) {
throw new RuntimeException(trackerName + " already has " +
"slots reserved for " +
jobForFallowReduceSlot + "; being" +
" asked to un-reserve for " + jobId);
}
jobForFallowReduceSlot = null;
}
job.unreserveTaskTracker(this, taskType);
LOG.info(trackerName + ": Unreserved " + taskType + " slots for " + jobId);
}
/**
* Cleanup when the {@link TaskTracker} is declared as 'lost/blacklisted'
* by the JobTracker.
*
* The method assumes that the lock on the {@link JobTracker} is obtained
* by the caller.
*/
public void cancelAllReservations() {
// Inform jobs which have reserved slots on this tasktracker
if (jobForFallowMapSlot != null) {
unreserveSlots(TaskType.MAP, jobForFallowMapSlot);
}
if (jobForFallowReduceSlot != null) {
unreserveSlots(TaskType.REDUCE, jobForFallowReduceSlot);
}
}
}