MYSQL dead but pid file exists问题 - ****博客
https://blog.****.net/shilian_h/article/details/38020567
Error "mysqld dead but pid file exists" - Stack Overflow
https://*.com/questions/24831119/error-mysqld-dead-but-pid-file-exists
mysqld dead but pid file exists - ****博客
https://blog.****.net/zhoujj303030/article/details/44455165
方案一亲测有效，方案二三应该也可以（未测）。