Oracle 10g Lsnrctl does not reflect the inability to connect to the database, oraclelsnrctl

Oracle 10g Lsnrctl does not reflect the inability to connect to the database, oraclelsnrctl
Symptom Description: The oracle version used is 10.2.0.1.0 in linux. If lsnrctl status is entered on the command line interface, no response is returned. If lsnrctl stop is entered, no response is returned. Applications connected to the database run normally, but new applications cannot connect to the database. SQL plus is normal on the oracle database server, but PL/SQL and Navicat on the client cannot connect to the database server.

Problem diagnosis: oracle listening is down

After querying the information online, it is found that this is caused by a bug 4518443 in oracle 10.2.0.1.0. This bug will automatically create a sublistener. When this happens, the listener will be suspended. The BUG exists in any operating system.

Solution:
1. view the LISTNER process (both statements are acceptable)
$ Ps aux | grep LISTENER
$ Ps aux | grep tnslsnr
Normally, there is only one LISTENER process, and this BUG shows two LISTENER processes, so you need to close one process.

2. kill the LISTENER process (kill is required for both processes)
$ Kill-9 26184

3. Restart LISTENER.
$ Lsnrctl stop
$ Lsnrctl start

4. view the LISTNER process again
$ Ps aux | grep LISTENER

Oracle 9635 10.8 0.0 204508 9512? Rsl Sep18 620: 18 $ ORACLE_HOME/bin/tnslsnr LISTENER-inherit

At this time, only one LISTENER process exists.

So far, the LISTENER can be used normally. If no further processing is performed, the same problem will still occur in a period of time. Therefore, we need to completely solve this problem.

5. Complete Solution
5.1: upgrade solution
You can Upgrade oracle to a version later than oracle 10.2.0.3.
Ps: there is a great risk of upgrading the online production database online. Once the upgrade fails, all online applications cannot be accessed, therefore, we do not recommend that you use this method to solve this problem for production databases used online, unless they are used online after the upgrade.

5.2: Modify the listener. ora File
Add the following parameter to the listener. ora file: SUBSCRIBE_FOR_NODE_DOWN_EVENT _ <listener_name> = OFF # Here, listener_name is the name of the configured listener, if it is the default LISTENER. The specific modification is as follows:

$ Vi $ ORACLE_HOME/network/admin/listener. ora

SUBSCRIBE_FOR_NODE_DOWN_EVENT_LISTENER = OFF

# It can be added to the last row.

Then restart LISTENER.
$ Lsnrctl stop
$ Lsnrctl start

Note: If you only modify this BUG, we recommend that you modify the listener. ora file and remind you to Upgrade ORACLE before it is officially put into online use.