code: void removeMarkedTasks(String taskTracker) {
      // Purge all the 'marked' tasks which were running at taskTracker
      Set<TaskAttemptID> markedTaskSet =
        trackerToMarkedTasksMap.get(taskTracker);
      if (markedTaskSet != null) {
        for (TaskAttemptID taskid : markedTaskSet) {
          removeTaskEntry(taskid);
          if (LOG.isDebugEnabled()) {
            LOG.debug("Removed marked completed task '" + taskid + "' from '" +
                      taskTracker + "'");
          }
        }
        // Clear
        trackerToMarkedTasksMap.remove(taskTracker);
      }
    }
docs: Remove all 'marked' tasks running on a given {@link TaskTracker}
  from the {@link JobTracker}'s data-structures.
  This function assumes that the JobTracker is locked on entry.
  
  @param taskTracker tasktracker whose 'non-running' tasks are to be purged