void removeTaskEntry(String taskid) {
// taskid --> tracker
String tracker = (String) taskidToTrackerMap.remove(taskid);
// tracker --> taskid
TreeSet trackerSet = (TreeSet) trackerToTaskMap.get(tracker);
if (trackerSet != null) {
trackerSet.remove(taskid);
}
// taskid --> TIP
taskidToTIPMap.remove(taskid);
}
/**
* We lost the task tracker! All task-tracker structures have already been updated. Just process
* the contained tasks and any jobs that might be affected.
*/
void lostTaskTracker(String trackerName) {
LOG.info("Lost tracker '" + trackerName + "'");
TreeSet lostTasks = (TreeSet) trackerToTaskMap.get(trackerName);
trackerToTaskMap.remove(trackerName);
if (lostTasks != null) {
for (Iterator it = lostTasks.iterator(); it.hasNext(); ) {
String taskId = (String) it.next();
TaskInProgress tip = (TaskInProgress) taskidToTIPMap.get(taskId);
// Tell the job to fail the relevant task
JobInProgress job = tip.getJob();
job.failedTask(tip, taskId, trackerName);
}
}
}
public synchronized JobStatus getJobStatus(String jobid) {
JobInProgress job = (JobInProgress) jobs.get(jobid);
if (job != null) {
return job.getStatus();
} else {
return null;
}
}
public synchronized JobProfile getJobProfile(String jobid) {
JobInProgress job = (JobInProgress) jobs.get(jobid);
if (job != null) {
return job.getProfile();
} else {
return null;
}
}
/**
* A tracker wants to know if any of its Tasks have been closed (because the job completed,
* whether successfully or not)
*/
public synchronized String pollForTaskWithClosedJob(String taskTracker) {
TreeSet taskIds = (TreeSet) trackerToTaskMap.get(taskTracker);
if (taskIds != null) {
for (Iterator it = taskIds.iterator(); it.hasNext(); ) {
String taskId = (String) it.next();
TaskInProgress tip = (TaskInProgress) taskidToTIPMap.get(taskId);
if (tip.shouldCloseForClosedJob(taskId)) {
//
// This is how the JobTracker ends a task at the TaskTracker.
// It may be successfully completed, or may be killed in
// mid-execution.
//
return taskId;
}
}
}
return null;
}
/**
* A TaskTracker wants to know the physical locations of completed, but not yet closed, tasks.
* This exists so the reduce task thread can locate map task outputs.
*/
public synchronized MapOutputLocation[] locateMapOutputs(
String taskId, String[][] mapTasksNeeded) {
ArrayList v = new ArrayList();
for (int i = 0; i < mapTasksNeeded.length; i++) {
for (int j = 0; j < mapTasksNeeded[i].length; j++) {
TaskInProgress tip = (TaskInProgress) taskidToTIPMap.get(mapTasksNeeded[i][j]);
if (tip != null && tip.isComplete(mapTasksNeeded[i][j])) {
String trackerId = (String) taskidToTrackerMap.get(mapTasksNeeded[i][j]);
TaskTrackerStatus tracker;
synchronized (taskTrackers) {
tracker = (TaskTrackerStatus) taskTrackers.get(trackerId);
}
v.add(new MapOutputLocation(mapTasksNeeded[i][j], tracker.getHost(), tracker.getPort()));
break;
}
}
}
// randomly shuffle results to load-balance map output requests
Collections.shuffle(v);
return (MapOutputLocation[]) v.toArray(new MapOutputLocation[v.size()]);
}
/**
* Update the last recorded status for the given task tracker. It assumes that the taskTrackers
* are locked on entry.
*
* @author Owen O'Malley
* @param trackerName The name of the tracker
* @param status The new status for the task tracker
* @return Was an old status found?
*/
private boolean updateTaskTrackerStatus(String trackerName, TaskTrackerStatus status) {
TaskTrackerStatus oldStatus = (TaskTrackerStatus) taskTrackers.get(trackerName);
if (oldStatus != null) {
totalMaps -= oldStatus.countMapTasks();
totalReduces -= oldStatus.countReduceTasks();
if (status == null) {
taskTrackers.remove(trackerName);
}
}
if (status != null) {
totalMaps += status.countMapTasks();
totalReduces += status.countReduceTasks();
taskTrackers.put(trackerName, status);
}
return oldStatus != null;
}
public synchronized TaskReport[] getReduceTaskReports(String jobid) {
JobInProgress job = (JobInProgress) jobs.get(jobid);
if (job == null) {
return new TaskReport[0];
} else {
Vector reports = new Vector();
Vector completeReduceTasks = job.reportTasksInProgress(false, true);
for (Iterator it = completeReduceTasks.iterator(); it.hasNext(); ) {
TaskInProgress tip = (TaskInProgress) it.next();
reports.add(tip.generateSingleReport());
}
Vector incompleteReduceTasks = job.reportTasksInProgress(false, false);
for (Iterator it = incompleteReduceTasks.iterator(); it.hasNext(); ) {
TaskInProgress tip = (TaskInProgress) it.next();
reports.add(tip.generateSingleReport());
}
return (TaskReport[]) reports.toArray(new TaskReport[reports.size()]);
}
}
/**
* Accept and process a new TaskTracker profile. We might have known about the TaskTracker
* previously, or it might be brand-new. All task-tracker structures have already been updated.
* Just process the contained tasks and any jobs that might be affected.
*/
void updateTaskStatuses(TaskTrackerStatus status) {
for (Iterator it = status.taskReports(); it.hasNext(); ) {
TaskStatus report = (TaskStatus) it.next();
TaskInProgress tip = (TaskInProgress) taskidToTIPMap.get(report.getTaskId());
if (tip == null) {
LOG.info(
"Serious problem. While updating status, cannot find taskid " + report.getTaskId());
} else {
JobInProgress job = tip.getJob();
job.updateTaskStatus(tip, report);
if (report.getRunState() == TaskStatus.SUCCEEDED) {
job.completedTask(tip, report.getTaskId());
} else if (report.getRunState() == TaskStatus.FAILED) {
// Tell the job to fail the relevant task
job.failedTask(tip, report.getTaskId(), status.getTrackerName());
}
}
}
}
///////////////////////////////////////////////////////
// Maintain lookup tables; called by JobInProgress
// and TaskInProgress
///////////////////////////////////////////////////////
void createTaskEntry(String taskid, String taskTracker, TaskInProgress tip) {
LOG.info(
"Adding task '"
+ taskid
+ "' to tip "
+ tip.getTIPId()
+ ", for tracker '"
+ taskTracker
+ "'");
// taskid --> tracker
taskidToTrackerMap.put(taskid, taskTracker);
// tracker --> taskid
TreeSet taskset = (TreeSet) trackerToTaskMap.get(taskTracker);
if (taskset == null) {
taskset = new TreeSet();
trackerToTaskMap.put(taskTracker, taskset);
}
taskset.add(taskid);
// taskid --> TIP
taskidToTIPMap.put(taskid, tip);
}
///////////////////////////////////////////////////////////////
// JobTracker methods
///////////////////////////////////////////////////////////////
public JobInProgress getJob(String jobid) {
return (JobInProgress) jobs.get(jobid);
}
public synchronized void killJob(String jobid) {
JobInProgress job = (JobInProgress) jobs.get(jobid);
job.kill();
}
/**
* A tracker wants to know if there's a Task to run. Returns a task we'd like the TaskTracker to
* execute right now.
*
* <p>Eventually this function should compute load on the various TaskTrackers, and incorporate
* knowledge of DFS file placement. But for right now, it just grabs a single item out of the
* pending task list and hands it back.
*/
public synchronized Task pollForNewTask(String taskTracker) {
//
// Compute average map and reduce task numbers across pool
//
int avgMaps = 0;
int avgReduces = 0;
int numTaskTrackers;
TaskTrackerStatus tts;
synchronized (taskTrackers) {
numTaskTrackers = taskTrackers.size();
tts = (TaskTrackerStatus) taskTrackers.get(taskTracker);
}
if (numTaskTrackers > 0) {
avgMaps = totalMaps / numTaskTrackers;
avgReduces = totalReduces / numTaskTrackers;
}
int totalCapacity = numTaskTrackers * maxCurrentTasks;
//
// Get map + reduce counts for the current tracker.
//
if (tts == null) {
LOG.warning("Unknown task tracker polling; ignoring: " + taskTracker);
return null;
}
int numMaps = tts.countMapTasks();
int numReduces = tts.countReduceTasks();
//
// In the below steps, we allocate first a map task (if appropriate),
// and then a reduce task if appropriate. We go through all jobs
// in order of job arrival; jobs only get serviced if their
// predecessors are serviced, too.
//
//
// We hand a task to the current taskTracker if the given machine
// has a workload that's equal to or less than the averageMaps
// +/- TASK_ALLOC_EPSILON. (That epsilon is in place in case
// there is an odd machine that is failing for some reason but
// has not yet been removed from the pool, making capacity seem
// larger than it really is.)
//
synchronized (jobsByArrival) {
if ((numMaps < maxCurrentTasks) && (numMaps <= (avgMaps + TASK_ALLOC_EPSILON))) {
int totalNeededMaps = 0;
for (Iterator it = jobsByArrival.iterator(); it.hasNext(); ) {
JobInProgress job = (JobInProgress) it.next();
if (job.getStatus().getRunState() != JobStatus.RUNNING) {
continue;
}
Task t = job.obtainNewMapTask(taskTracker, tts);
if (t != null) {
return t;
}
//
// Beyond the highest-priority task, reserve a little
// room for failures and speculative executions; don't
// schedule tasks to the hilt.
//
totalNeededMaps += job.desiredMaps();
double padding = 0;
if (totalCapacity > MIN_SLOTS_FOR_PADDING) {
padding = Math.min(maxCurrentTasks, totalNeededMaps * PAD_FRACTION);
}
if (totalNeededMaps + padding >= totalCapacity) {
break;
}
}
}
//
// Same thing, but for reduce tasks
//
if ((numReduces < maxCurrentTasks) && (numReduces <= (avgReduces + TASK_ALLOC_EPSILON))) {
int totalNeededReduces = 0;
for (Iterator it = jobsByArrival.iterator(); it.hasNext(); ) {
JobInProgress job = (JobInProgress) it.next();
if (job.getStatus().getRunState() != JobStatus.RUNNING) {
continue;
}
Task t = job.obtainNewReduceTask(taskTracker, tts);
if (t != null) {
return t;
}
//
// Beyond the highest-priority task, reserve a little
// room for failures and speculative executions; don't
// schedule tasks to the hilt.
//
totalNeededReduces += job.desiredReduces();
double padding = 0;
if (totalCapacity > MIN_SLOTS_FOR_PADDING) {
padding = Math.min(maxCurrentTasks, totalNeededReduces * PAD_FRACTION);
}
if (totalNeededReduces + padding >= totalCapacity) {
break;
}
}
}
}
return null;
}
public TaskTrackerStatus getTaskTracker(String trackerID) {
synchronized (taskTrackers) {
return (TaskTrackerStatus) taskTrackers.get(trackerID);
}
}