Ubuntu 23系统中MySQL Server 8.0无法启动求助

问题场景 #

通过以下命令安装MySQL：

sudo apt install MySQL-Server

安装完成后服务无法正常启动，一直处于激活（自动重启）状态。

执行命令及输出 #

执行以下命令排查服务状态：

systemctl status mysql.service
journalctl -xeu mysql.service

输出内容如下：

mysql.service - MySQL Community Server
     Loaded: loaded (/lib/systemd/system/mysql.service; enabled; preset: enabled)
     Active: activating (auto-restart) (Result: oom-kill) since Sat 2023-07-29 08:01:47 PDT; 227ms ago
    Process: 2378 ExecStartPre=/usr/share/mysql/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
    Process: 2386 ExecStart=/usr/sbin/mysqld (code=killed, signal=KILL)
   Main PID: 2386 (code=killed, signal=KILL)
     Status: "Server startup in progress"
        CPU: 2.649s

Jul 29 08:01:47 ubuntu systemd[1]: mysql.service: A process of this unit has been killed by the OOM killer.
Jul 29 08:01:47 ubuntu systemd[1]: mysql.service: Main process exited, code=killed, status=9/KILL
Jul 29 08:01:47 ubuntu systemd[1]: mysql.service: Failed with result 'oom-kill'.
Jul 29 08:01:47 ubuntu systemd[1]: Failed to start mysql.service - MySQL Community Server.
Jul 29 08:01:47 ubuntu systemd[1]: mysql.service: Consumed 2.649s CPU time.
Jul 29 08:01:47 ubuntu systemd[1]: mysql.service: Scheduled restart job, restart counter is at 71.
Jul 29 08:01:47 ubuntu systemd[1]: Stopped mysql.service - MySQL Community Server.
Jul 29 08:01:47 ubuntu systemd[1]: mysql.service: Consumed 2.649s CPU time.
Jul 29 08:01:47 ubuntu systemd[1]: Starting mysql.service - MySQL Community Server...
:~$ journalctl -xeu mysql.service
Jul 29 08:02:43 ubuntu systemd[1]: mysql.service: Scheduled restart job, restart counter is at 76.
░░ Subject: Automatic restarting of a unit has been scheduled
░░ Defined-By: systemd
░░ Support: http://www.ubuntu.com/support
░░
░░ Automatic restarting of the unit mysql.service has been scheduled, as the result for
░░ the configured Restart= setting for the unit.
Jul 29 08:02:43 ubuntu systemd[1]: Stopped mysql.service - MySQL Community Server.
░░ Subject: A stop job for unit mysql.service has finished
░░ Defined-By: systemd
░░ Support: http://www.ubuntu.com/support
░░
░░ A stop job for unit mysql.service has finished.
░░
░░ The job identifier is 8529 and the job result is done.
Jul 29 08:02:43 ubuntu systemd[1]: mysql.service: Consumed 2.685s CPU time.
░░ Subject: Resources consumed by unit runtime
░░ Defined-By: systemd
░░ Support: http://www.ubuntu.com/support
░░
░░ The unit mysql.service completed and consumed the indicated resources.
Jul 29 08:02:43 ubuntu systemd[1]: Starting mysql.service - MySQL Community Server...
░░ Subject: A start job for unit mysql.service has begun execution
░░ Defined-By: systemd
░░ Support: http://www.ubuntu.com/support
░░
░░ A start job for unit mysql.service has begun execution.
░░
░░ The job identifier is 8529.

已尝试操作 #

多次执行purge、clean、autoremove和update命令，问题仍未解决。

解决方法 #

从日志可明确：MySQL进程被**OOM Killer（内存不足终止器）**杀死，核心原因是系统可用内存不足以支撑MySQL启动，按以下步骤处理：

• 临时释放内存
  用htop查看高内存占用进程，手动关闭不需要的进程；或执行以下命令清理缓存：

  sudo sync && sudo sysctl -w vm.drop_caches=3
  

• 调整MySQL内存配置
  编辑MySQL配置文件（通常路径为/etc/mysql/mysql.conf.d/mysqld.cnf），降低内存相关参数（以1G内存系统为例）：

  sudo nano /etc/mysql/mysql.conf.d/mysqld.cnf
  

  修改以下参数：

  innodb_buffer_pool_size = 128M
  key_buffer_size = 32M
  max_connections = 50
  query_cache_size = 0
  

  保存后重启服务：

  sudo systemctl restart mysql
  

• 长期解决方案
  若为虚拟机/云服务器，升级实例内存；若为物理机，加装内存条。

内容的提问来源于stack exchange，提问作者Gunyen