/**
* Check if a task can be killed to increase free memory
*
* @param tid task attempt ID
* @return true if the task can be killed
*/
private boolean isKillable(TaskAttemptID tid) {
TaskInProgress tip = taskTracker.runningTasks.get(tid);
return tip != null
&& !tip.wasKilled()
&& (tip.getRunState() == TaskStatus.State.RUNNING
|| tip.getRunState() == TaskStatus.State.COMMIT_PENDING);
}
private void killTasksWithLeastProgress(long memoryStillInUsage) {
List<TaskAttemptID> tasksToKill = new ArrayList<TaskAttemptID>();
List<TaskAttemptID> tasksToExclude = new ArrayList<TaskAttemptID>();
// Find tasks to kill so as to get memory usage under limits.
while (memoryStillInUsage > maxMemoryAllowedForAllTasks) {
// Exclude tasks that are already marked for
// killing.
TaskInProgress task = taskTracker.findTaskToKill(tasksToExclude);
if (task == null) {
break; // couldn't find any more tasks to kill.
}
TaskAttemptID tid = task.getTask().getTaskID();
if (processTreeInfoMap.containsKey(tid)) {
ProcessTreeInfo ptInfo = processTreeInfoMap.get(tid);
ProcfsBasedProcessTree pTree = ptInfo.getProcessTree();
memoryStillInUsage -= pTree.getCumulativeVmem();
tasksToKill.add(tid);
}
// Exclude this task from next search because it is already
// considered.
tasksToExclude.add(tid);
}
// Now kill the tasks.
if (!tasksToKill.isEmpty()) {
for (TaskAttemptID tid : tasksToKill) {
String msg =
"Killing one of the least progress tasks - "
+ tid
+ ", as the cumulative memory usage of all the tasks on "
+ "the TaskTracker exceeds virtual memory limit "
+ maxMemoryAllowedForAllTasks
+ ".";
LOG.warn(msg);
killTask(tid, msg, false);
}
} else {
LOG.info(
"The total memory usage is overflowing TTs limits. "
+ "But found no alive task to kill for freeing memory.");
}
}