mysql的死锁问题分析与处理方法
前几天我的mysql突然出现大量死锁,全部需要一个个Kill id才能完成,下面我总结一下我最终解决死锁方法吧。
myISAM和MEMORY存储引擎采用的是表级锁table-level locking
死锁
所谓死锁
因争夺资源而造成的一种互相等待的现象,若无外力作用,它们都将无法推进下去.
此时称系统处于死锁状态或系统产生了死锁,这些永远在互相等竺的进程称为死锁进程.
表级锁不会产生死锁.所以解决死锁主要还是真对于最常用的InnoDB.
在遇到问题时
先执行show processlist找到死锁线程号.然后Kill processNo
当然主要解决还是需要去看一下具体的操作.可能产生死锁
Show innodb status检查引擎状态 ,可以看到哪些语句产生死锁
SHOW PROCESSLIST查看数据库中表的状态,是否被锁;
kill id //杀掉被锁的表
===================================================
代码如下 | 复制代码 |
set autocommit=0; select * from t1 where uid='xxxx' for update //在有索引(例如uid)的情况下是行锁,否则是表锁 insert into t1 values(1,'xxxxx'); commit; ===================================================== lock tables t1 write|read; insert into t1 values(2,'xxxxx'); //只有insert unlock tables; |
解决办法
1、全表扫描,没有可用的索引。
2、解决把你程序中的SQL,把IN改成JOIN,
3、在mysql中的my.ini中把数据库连接时间改小点。

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