private TaskAttemptId allocateLocalTask(String host) {
HostVolumeMapping hostVolumeMapping = leafTaskHostMapping.get(host);
if (hostVolumeMapping != null) { // tajo host is located in hadoop datanode
for (int i = 0; i < hostVolumeMapping.getRemainingLocalTaskSize(); i++) {
TaskAttemptId attemptId = hostVolumeMapping.getLocalTask();
if (attemptId == null) break;
// find remaining local task
if (leafTasks.contains(attemptId)) {
leafTasks.remove(attemptId);
return attemptId;
}
}
}
return null;
}
