private TaskAttemptId allocateRackTask(String host) {
List<HostVolumeMapping> remainingTasks = Lists.newArrayList(leafTaskHostMapping.values());
String rack = RackResolver.resolve(host).getNetworkLocation();
TaskAttemptId attemptId = null;
if (remainingTasks.size() > 0) {
synchronized (scheduledRequests) {
// find largest remaining task of other host in rack
Collections.sort(
remainingTasks,
new Comparator<HostVolumeMapping>() {
@Override
public int compare(HostVolumeMapping v1, HostVolumeMapping v2) {
// descending remaining tasks
if (v2.remainTasksNum.get() > v1.remainTasksNum.get()) {
return 1;
} else if (v2.remainTasksNum.get() == v1.remainTasksNum.get()) {
return 0;
} else {
return -1;
}
}
});
}
for (HostVolumeMapping tasks : remainingTasks) {
for (int i = 0; i < tasks.getRemainingLocalTaskSize(); i++) {
TaskAttemptId tId = tasks.getTaskAttemptIdByRack(rack);
if (tId == null) break;
if (leafTasks.contains(tId)) {
leafTasks.remove(tId);
attemptId = tId;
break;
}
}
if (attemptId != null) break;
}
}
// find task in rack
if (attemptId == null) {
HashSet<TaskAttemptId> list = leafTasksRackMapping.get(rack);
if (list != null) {
synchronized (list) {
Iterator<TaskAttemptId> iterator = list.iterator();
while (iterator.hasNext()) {
TaskAttemptId tId = iterator.next();
iterator.remove();
if (leafTasks.contains(tId)) {
leafTasks.remove(tId);
attemptId = tId;
break;
}
}
}
}
}
return attemptId;
}
