MySQL启动报错问题排查:InnoDB: Unable to lock ./ibdata1 error

By liuzhijun, 2016-03-03, 分类: 数据库

mysql, OSX

在OS X环境下MySQL启动时报错:

016-03-03T00:02:30.483037Z 0 [ERROR] InnoDB: Unable to lock ./ibdata1 error: 35
2016-03-03T00:02:30.483100Z 0 [Note] InnoDB: Check that you do not already have another mysqld process using the same InnoDB data or log files.

终端不断地重复打印上面的错误日志,从错误日志看起来似乎有另外一个mysqld进程占用了./ibdata1文件,于是使用ps命令查看是否有mysqld进程在运行:

ps -ef |grep mysqld
74  7711     1   0  8:04上午 ??         0:00.34 /usr/local/mysql/bin/mysqld --user=_mysql --basedir=/usr/local/mysql --datadir=/usr/local/mysql/data --plugin-dir=/usr/local/mysql/lib/plugin --log-error=/usr/local/mysql/data/mysqld.local.err --pid-file=/usr/local/mysql/data/mysqld.local.pid

发现有一个7711的进程在运行,于是强制kill掉:

sudo kill -9 7711

再次ps查询:

ps -ef |grep mysqld
74  7759     1   0  8:10上午 ??         0:00.29 /usr/local/mysql/bin/mysqld --user=_mysql --basedir=/usr/local/mysql --datadir=/usr/local/mysql/data --plugin-dir=/usr/local/mysql/lib/plugin --log-error=/usr/local/mysql/data/mysqld.local.err --pid-file=/usr/local/mysql/data/mysqld.local.pid

发现还在,只不过pid由原来的7711变成了现在的7759,那么看看mysqld进程打开了哪些文件:

lsof -c mysqld

该进程没有打开任何文件,这就见鬼了。

Mac OS X, lsof only shows your own processes unless running as root with sudo

于是再次运行:

sudo lsof -c mysqld
COMMAND  PID   USER   FD     TYPE             DEVICE  SIZE/OFF    NODE NAME
mysqld  8655 _mysql  cwd      DIR                1,4       544 3090250 /usr/local/mysql/data
mysqld  8655 _mysql  txt      REG                1,4  31130736 3089789 /usr/local/mysql/bin/mysqld

的确发现有一个实实在在的mysqld进程在运行,也占用的这些mysql文件,经过一番Google大法,发现在OS X中启动MySQL跟在Linux中启动方式完全是牛马不相及,在OS X中启动/重启MySQL的正确姿势是:

sudo launchctl unload -w /Library/LaunchDaemons/com.oracle.oss.mysql.mysqld.plist

此时再来看看是否还有mysqld进程:

ps -ef |grep mysqld

嗯,发现确实没有了,再来启动MySQL:

sudo launchctl load -w /Library/LaunchDaemons/com.oracle.oss.mysql.mysqld.plist

问题总算解决,但还没完,总得把原理搞清楚才行。

launchd是什么?

launchd是Mac OS X从10.4开始引入,用于用于初始化系统环境的关键进程,它是内核装载成功之后在OS环境下启动的第一个进程。传统的Linux会使用/etc/rc.*或者/etc/init来管理开机要启动的服务,而在OS X中就是使用launchd来管理。采用这种方式来配置启动项很简单,只需要一个plist文件。/Library/LaunchDaemons目录下的plist文件都是系统启动后立即启动进程。使用launchctl命令加载/卸载plist文件,加载配置文件后,程序启动,卸载配置文件后程序关闭。

卸载配置文件后又尝试直接用mysqld命令来启动mysql进程试试:

/usr/local/mysql/bin/mysqld
2016-03-03T01:35:50.359258Z 0 [ERROR] InnoDB: ./ib_logfile0 can't be opened in read-write mode.
2016-03-03T01:35:50.359283Z 0 [ERROR] InnoDB: Plugin initialization aborted with error Generic error
2016-03-03T01:35:50.670517Z 0 [ERROR] Plugin 'InnoDB' init function returned error.
2016-03-03T01:35:50.670555Z 0 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
2016-03-03T01:35:50.670568Z 0 [ERROR] Failed to initialize plugins.
2016-03-03T01:35:50.670574Z 0 [ERROR] Aborting

ib_logfile0不能被打开,猜测是用户权限文件,不能用当前系统用户启动mysql。那么加上sudo看看,用root来启动:

2016-03-03T01:38:10.977313Z 0 [ERROR] Fatal error: Please read "Security" section of the manual to find out how to run mysqld as root!

2016-03-03T01:38:10.977339Z 0 [ERROR] Aborting

2016-03-03T01:38:10.977350Z 0 [Note] Binlog end
2016-03-03T01:38:10.977410Z 0 [Note] /usr/local/mysql/bin/mysqld: Shutdown complete

叫我去读MySQL的安全手册,还是用launchd的方式启动吧。


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