如果连接时候变得较慢 查看Oracle日志记录，可能是因为此文件太大，超过2G，
需要定期清理，（如果多用户，记得用root，可能没权限）

查看listener.log？

find / -name listener.log

经查看，竟然高达2G得日志数据，由于一些老旧的OS不支持2GB以上的文件，故当listener.log文件
超过2GB时，会出现无法处理新的连接，新的操作系统虽然不会出现这个问题，但我们依然需要对其
进行定期处理清理。

Listener log日志文件处理

[oracle@localhost home]$ lsnrctl
LSNRCTL> set log_status off
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1521)))
LISTENER parameter "log_status" set to OFF
The command completed successfully
LSNRCTL> show log_status
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1521)))
LISTENER parameter "log_status" set to OFF
The command completed successfully
LSNRCTL> exit
[oracle@localhost home]$ find -name listener.log
home/oracle/app/oracle/diag/tnslsnr/localhost/listener/trace/listener.log
[oracle@localhost ~]$ cd /home/oracle/app/oracle/diag/tnslsnr/localhost/listener/trace/
[oracle@localhost trace]$ mv listener.log listener.log.20191127
[oracle@localhost trace]$ ls
listener.log.20191127  ora_2617_140154513196800.trc
[oracle@localhost trace]$ lsnrctl
LSNRCTL> set log_status on
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1521)))
LISTENER parameter "log_status" set to ON
The command completed successfully
LSNRCTL> show log_status 
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1521)))
LISTENER parameter "log_status" set to ON
The command completed successfully
LSNRCTL> reload
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1521)))
The command completed successfully
LSNRCTL> exit
[oracle@localhost trace]$

[oracle@localhost home]$ lsnrctl
LSNRCTL> set log_status off
LSNRCTL> show log_status
LSNRCTL> exit
[oracle@localhost home]$ find -name listener.log
[oracle@localhost trace]$ mv listener.log listener.log.20191127
LSNRCTL> set log_status on
LSNRCTL> reload

我们通过重命名日志文件之后，会自动生成一个新的listener.log文件。当然也可以进行清空处理，可以先
copy一下备份，然后进行清空处理。