/**
* Get the archive entries in classpath as an array of Path
*
* @param conf Configuration that contains the classpath setting
*/
public static Path[] getArchiveClassPaths(Configuration conf) {
String classpath = conf.get("mapred.job.classpath.archives");
if (classpath == null) return null;
ArrayList list =
Collections.list(new StringTokenizer(classpath, System.getProperty("path.separator")));
Path[] paths = new Path[list.size()];
for (int i = 0; i < list.size(); i++) {
paths[i] = new Path((String) list.get(i));
}
return paths;
}
public static <K extends Text, V extends IntWritable> Map<K, V> sortByValues(Map<K, V> map) {
List<Map.Entry<K, V>> entries = new LinkedList<Map.Entry<K, V>>(map.entrySet());
Collections.sort(
entries,
new Comparator<Map.Entry<K, V>>() {
public int compare(Map.Entry<K, V> o1, Map.Entry<K, V> o2) {
return o2.getValue().compareTo(o1.getValue());
}
});
Map<K, V> sortedMap = new LinkedHashMap<K, V>();
for (Map.Entry<K, V> entry : entries) {
sortedMap.put(entry.getKey(), entry.getValue());
}
return sortedMap;
}
/**
* 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()]);
}