code: private void addJobForCleanup(JobID id) {
      for (String taskTracker : taskTrackers.keySet()) {
        LOG.debug("Marking job " + id + " for cleanup by tracker " + taskTracker);
        synchronized (trackerToJobsToCleanup) {
          Set<JobID> jobsToKill = trackerToJobsToCleanup.get(taskTracker);
          if (jobsToKill == null) {
            jobsToKill = new HashSet<JobID>();
            trackerToJobsToCleanup.put(taskTracker, jobsToKill);
          }
          jobsToKill.add(id);
        }
      }
    }
docs: Add a job to cleanup for the tracker.