备库状态为read only with apply 但v$managed_standby却未见rfs进程信息

问题描述：备库状态为read only with apply,但查看v$managed_standby视图却未见rfs进程信息,如下所示.
SQL> select open_mode from v$database;

OPEN_MODE
--------------------
READ ONLY WITH APPLY
SQL> select process,status from v$managed_standby;

PROCESS   STATUS
--------- ------------
ARCH      CONNECTED
ARCH      CONNECTED
ARCH      CONNECTED
ARCH      CONNECTED
MRP0      APPLYING_LOG
异常原因：监听未开启.
[oracle@hisdbdg ~]$ lsnrctl status

LSNRCTL for Linux: Version 11.2.0.4.0 - Production on 02-OCT-2022 17:36:40

Copyright (c) 1991, 2013, Oracle.  All rights reserved.

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=192.168.133.165)(PORT=1521)))
TNS-12541: TNS:no listener
 TNS-12560: TNS:protocol adapter error
  TNS-00511: No listener
   Linux Error: 111: Connection refused
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1521)))
TNS-12541: TNS:no listener
 TNS-12560: TNS:protocol adapter error
  TNS-00511: No listener
   Linux Error: 111: Connection refused
[oracle@hisdbdg ~]$ lsnrctl start

LSNRCTL for Linux: Version 11.2.0.4.0 - Production on 02-OCT-2022 17:36:46

Copyright (c) 1991, 2013, Oracle.  All rights reserved.

Starting /u01/app/oracle/product/11.2.0/db_1/bin/tnslsnr: please wait...

TNSLSNR for Linux: Version 11.2.0.4.0 - Production
System parameter file is /u01/app/oracle/product/11.2.0/db_1/network/admin/listener.ora
Log messages written to /u01/app/oracle/diag/tnslsnr/hisdbdg/listener/alert/log.xml
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.133.165)(PORT=1521)))
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC1521)))

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=192.168.133.165)(PORT=1521)))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for Linux: Version 11.2.0.4.0 - Production
Start Date                02-OCT-2022 17:36:48
Uptime                    0 days 0 hr. 0 min. 0 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      OFF
Listener Parameter File   /u01/app/oracle/product/11.2.0/db_1/network/admin/listener.ora
Listener Log File         /u01/app/oracle/diag/tnslsnr/hisdbdg/listener/alert/log.xml
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.133.165)(PORT=1521)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC1521)))
Services Summary...
Service "orcldg" has 1 instance(s).
  Instance "orcldg", status UNKNOWN, has 1 handler(s) for this service...
The command completed successfully
SQL> select process,status from v$managed_standby;

PROCESS   STATUS
--------- ------------
ARCH      CONNECTED
ARCH      CLOSING
ARCH      CONNECTED
ARCH      CLOSING
MRP0      APPLYING_LOG
RFS       IDLE
RFS       IDLE
RFS       IDLE
RFS       IDLE
RFS       IDLE
RFS       IDLE

PROCESS   STATUS
--------- ------------
RFS       IDLE
RFS       IDLE

13 rows selected.

结论：如上所示，监听开启后进程rfs显示正常.