由于之前linux服务器的MySQL数据库经常失灵，很多人也是不知道怎么样才好解决？
所以使用Monit监控程序监控MySQL，但是Monit监控MySQL经常无故失效……
Monit程序监控MySQL邮件警报通知
如果Monit监控程序MySQL数据库出现问题，会收到以下邮件通知。
monit alert — Timeout mysql
Timeout Service mysql
Date: Fri, 05 Feb 2021 04:55:47
Action: unmonitor
Host: chenweiliang.com
Description: service restarted 4 times within 4 cycles(s) – unmonitor
Your faithful employee,
Monit
monit alert — Does not exist mysql
Does not exist Service mysql
Date: Fri, 05 Feb 2021 04:47:21
Action: restart
Host: chenweiliang.com
Description: process is not running
Your faithful employee,
Monit
monit alert — Execution failed mysql
Execution failed Service mysql
Date: Fri, 05 Feb 2021 04:47:53
Action: alert
Host: chenweiliang.com
Description: failed to start (exit status 0) — no output
Your faithful employee,
Monit
如果收到以下邮件通知：
monit alert — Does not exist mysql
即表示MySQL数据库的PID文件不存在或路径不对。
此时，可通过查询mysql的pidfile命令，找到MySQL数据库进程的pidfile文件在哪里。
以下2个SSH命令，都能查看MySQL数据库进程的pidfile文件 ▼
ps -ef|grep mysqldwatch -n 1 "ps -ef | grep mysql"
SSH返回查询结果如下：
root 6206 1 0 16:19 ? 00:00:00 /bin/sh /usr/bin/mysqld_safe --datadir=/var/lib/mysql --pid-file=/var/lib/mysql/CentOS-UFO.pid
mysql 6280 6206 3 16:19 ? 00:00:22 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/lib/mysql/centos-ufo.err --pid-file=/var/lib/mysql/centos-ufo.pid
root 6691 1844 0 16:29 pts/0 00:00:00 grep mysqld登录Monit Service Manager
建议浏览器登录Monit Service Manager启动MySQL服务：
自己的域名:2812/
说明：
登录后，可查看Monit监控的服务进程：
| Process | Status | Uptime | CPU Total | Memory Total |
|---|---|---|---|---|
| apache | Running | 8m | 0.0% | 4.6% [23.3 MB] |
| mysqld | Not monitored | 26m | 1.6% | 19.3% [96.4 MB] |
若服务进程不处于“Running”的状态，可以点击服务名称，比如“mysqld”进入该服务进程的管理页面。
然后，点击以下右下角的“Enable monitoring”启动。
Process status
| Parameter | Value | |
|---|---|---|
| Name | mysqld | |
| Pid file | /var/lib/mysql/do.ufo.org.in.pid | |
| Status | Not monitored | |
| Group | database | |
| Monitoring mode | active | |
| Monitoring status | Not monitored | |
| Start program | ‘/etc/init.d/mysql start’ timeout 30 second(s) | |
| Stop program | ‘/etc/init.d/mysql stop’ timeout 30 second(s) | |
| Process id | – | |
| Parent process id | – | |
| UID | – | |
| Effective UID | – | |
| GID | – | |
| Process uptime | – | |
| Children | – | |
| CPU usage | – | |
| Total CPU usage (incl. children) | – | |
| Memory usage | – | |
| Total memory usage (incl. children) | – | |
| Port Response time | – | |
| Data collected | Mon, 21 Aug 2017 12:39:25 | |
| Timeout | If restarted 3 times within 5 cycle(s) then unmonitor | |
| Existence | If doesn’t exist then restart | |
| Port | If failed [localhost]:3306 type TCP/IP protocol DEFAULT with timeout 5 seconds then restart |
当Status（状态）处于“Running”时，即表示已经成功启动该进程监控了。
更换监控mysql的配置
不过，陈沩亮之前研究发现，另外也可以通过更换监控mysql的配置，让监控mysql失灵后重新激活monit程序监控mysql，此方法比较麻烦，所以仅供参考，不推荐使用。
实际操作：
然后，进入monit日志“monit.log”的目录路经：
cd /var/log重新启动monit程序：
service monit restart再测试重新启动mysqld：
service mysqld restart按“CRRL+R”刷新查看monit日志“monit.log”是否有重启mysql的记录？
有类似如下记录表示成功重新激活monit程序监控mysql：
[UTC Oct 23 06:37:55] error : ‘mysql’ process PID changed from 3521 to 4238
[UTC Oct 23 06:37:55] error : ‘mysql’ process PPID changed from 3313 to 4030
[UTC Oct 23 06:38:25] info : ‘mysql’ process PID has not changed since last cycle
[UTC Oct 23 06:38:25] info : ‘mysql’ process PPID has not changed since last cycle
下面是我用monit监控mysql配置：
monit配置监控mysql（一）
##监控mysql（一）#check process mysqld with pidfile /var/run/mysqld/mysqld.pidstart program = "/etc/init.d/mysqld start"stop program = "/etc/init.d/mysqld stop"if failed host localhost port 3306 for 3 times within 4 cycles then alert#若在四个周期内，三次 3306（Mysql）端口都无法连通，则邮件通知if 5 restarts within 5 cycles then timeout
monit配置监控mysql（二）
##监控mysql（二）#check process mysql with pidfile /var/run/mysqld/mysqld.pidstart program = "/etc/init.d/mysqld start" with timeout 10 secondsstop program = "/etc/init.d/mysqld stop"if failed host localhost port 3306 protocol mysqlwith timeout 10 secondsthen restartif 3 restarts within 5 cycles then timeoutif changed pid then alertgroup webserver
monit配置监控mysql（三）
##监控mysql#check process mysql with pidfile /var/run/mysqld/mysqld.pidgroup databasestart program = "/etc/init.d/mysqld start"stop program = "/etc/init.d/mysqld stop"if failed port 3306 then restartif 3 restarts within 10 cycles then timeout
后记：之前本人负责优化的网站 外星人UFO真相 经常遇到数据库奔溃、MySQL无故暂停的问题，现在经过以上的解救方案终于解决好了。
要是还没能解决，推荐参考以下教程 ▼
如何在CentOS Webpanel（CWP7）安装Monit监控软件？
在本教程中，我们将向你展示如何在CentOS 7上的CentOS Webpanel（CWP7）安装Monit监控。 Monit监控是什么？ Monit监控是一个免费的开源软件，它是一个非常有用的Linux监控程序。它可以……
