code: private void purgeDeadJobInstances(DbConn cnx, Node node)
      {
          for (JobInstance ji : JobInstance.select(cnx, "ji_select_by_node", node.getId()))
          {
              try
              {
                  cnx.runSelectSingle("history_select_state_by_id", String.class, ji.getId());
              }
              catch (NoResultException e)
              {
                  History.create(cnx, ji, State.CRASHED, Calendar.getInstance());
                  Message.create(cnx,
                          "Job was supposed to be running at server startup - usually means it was killed along a server by an admin or a crash",
                          ji.getId());
              }
  
              cnx.runUpdate("ji_delete_by_id", ji.getId());
          }
          cnx.commit();
      }
docs: To be called at node startup - it purges all job instances associated to this node.
  
  @param cnx
  @param node