In CentOS, the Web server's CPU load exceeds the threshold and the shell script is automatically restarted.

Note:
 
Operating system: CentOS
 
Web server: apache
 
Problem:
 
Search engine crawlers increase website access volume in a certain period of time. The server is under heavy pressure, the website access times out, and the page cannot be opened.
 
Solution:
 
Regularly monitors server load. After a threshold value is exceeded, the web service is automatically restarted.
 
Apache installation directory:/usr/local/apache
 
Script running log file:/usr/local/apache/check_cpu_load.log
 
Script storage directory:/home/crontab
 
Cd/home/crontab
 
Vi check_cpu_load.sh # edit and add the following code
 
#! /Bin/sh
 
# Crontab: */5 *****/home/crontab/check_cpu_load.sh>/usr/local/apache/check_cpu_load.log
 
TOP_SYS_LOAD_NUM = 3
 
SYS_LOAD_NUM = 'uptime | awk' {print $ (NF-2)} '| sed's /,//''
 
Echo $ (date + "% y-% m-% d") 'uptime'
 
If ['echo "$ TOP_SYS_LOAD_NUM <$ SYS_LOAD_NUM" | bc '-eq 1]
 
Then
 
Echo "#0 #" $ (date + "% y-% m-% d % H: % M: % S ") "pkill httpd" 'PS-ef | grep httpd | wc-L'>/usr/local/apache/check_cpu_load.log
 
/Usr/local/apache/bin/apachectl stop
 
Sleep 5
 
Pkill httpd
 
Sleep 5
 
For I in 1 2 3
 
Do
 
If ['pgrep httpd | wc-L'-le 0]
 
Then
 
/Usr/local/apache/bin/apachectl start
 
Sleep 30
 
Echo "#1 #" $ (date + "% y-% m-% d % H: % M: % S ") "start httpd" 'PS-ef | grep httpd | wc-L'>/usr/local/apache/check_cpu_load.log
 
Fi
 
Done
 
Else
 
If ['pgrep httpd | wc-L'-le 0]
 
Then
 
/Usr/local/apache/bin/apachectl start
 
Sleep 30
 
Echo "#2 #" $ (date + "% y-% m-% d % H: % M: % S ") "start httpd" 'PS-ef | grep httpd | wc-L'>/usr/local/apache/check_cpu_load.log
 
Fi
 
Fi
 
: Wq! # Save and exit
 
Crontab-e # Add a scheduled task
 
*/5 */home/crontab/check_cpu_load.sh>/usr/local/apache/check_cpu_load.log
 
: Wq! # Save and exit
 
Service crond restart # restart a scheduled task
 
After the preceding settings, when the server load exceeds 3, the script is automatically run within 5 minutes, and the apache service is restarted to restore the website access.