public static function releaseConn(RODSConn $conn)
 {
     $manager = $GLOBALS['RODSConnManager'];
     $conn_sig = $conn->getSignature();
     //echo "id:".$conn->getId()." ".implode(",",array_keys($manager->conn_map[$conn_sig]))."<br/>\n";
     if (isset($manager->conn_map[$conn_sig][$conn->getId()])) {
         $manager->conn_map[$conn_sig][$conn->getId()]->unlock();
     }
 }