Failure to connect due to improper parameter setting of Rac environment database node. Troubleshooting

A user encountered RAC A node of the database , The application cannot connect to the database . It is found that the database listener is abnormal , Unable to establish connection . After a series of investigations , It is found that some parameter settings during database installation are unreasonable , After the system runs for a long time , There are some problems .

[grid@rac-a ~]$ uptime -- node 1 Long startup time
 11:55:12 up 263 days,  2:38,  2 users,  load average: 1.53, 1.73, 1.85

[oracle@rac-b ~]$ uptime
 11:55:37 up 95 days, 18:55,  1 user,  load average: 1.99, 2.07, 1.99

One 、 node 1 Error message ：
7-FEB-2022 11:13:06 * (CONNECT_DATA=(SERVICE_NAME=orcl)(CID=(PROGRAM=D:\20211229\AAAexe)(HOST=** Register )(USER=Administrator))) * (ADDRESS=(PROTOCOL=tcp)(HOST=192.168.111.12)(PORT=1486)) * establish * orcl * 0
17-FEB-2022 11:13:07 * (CONNECT_DATA=(SERVICE_NAME=orcl)(CID=(PROGRAM=Python)(HOST=NUC.local)(USER=hby))) * (ADDRESS=(PROTOCOL=tcp)(HOST=192.168.5.66)(PORT=57609)) * establish * orcl * 12518
TNS-12518: TNS:listener could not hand off client connection
 TNS-12536: TNS:operation would block
  TNS-12560: TNS:protocol adapter error
   TNS-00506: Operation would block
    Linux Error: 11: Resource temporarily unavailable
    
Two 、 Problem analysis ：
Reference resources ORACLE file UNIX: TNS-12518,TNS-12536 When Listener Load Increases (Doc ID 1920559.1), After verification, it is necessary to modify and increase the corresponding kernel parameters .

3、 ... and 、 Problem handling ：   
Currently in RAC Database nodes 1 The following operations are carried out on the host （ The host and cluster are not restarted 、 database ）

1. Modifying kernel system parameters ：/etc/sysctl.conf
kernel.shmmax = 4398046511104
kernel.shmall = 1073741824
kernel.sem = 1010 128000 1010 256
fs.aio-max-nr = 3145728