code: function purgeJunkUnhandledJoints() {
  	if (bCatchingUp || Date.now() - coming_online_time < 3600 * 1000)
  		return;
  
  	db.query("DELETE FROM unhandled_joints WHERE creation_date < " + db.addTime("-1 HOUR"), function () {
  		db.query("DELETE FROM dependencies WHERE NOT EXISTS (SELECT * FROM unhandled_joints WHERE unhandled_joints.unit=dependencies.unit)");
  	});
  }
docs: We may receive a reference to a nonexisting unit in parents. We are not going to keep the referencing joint forever.