如何在MySQL上造成死锁

Question

出于测试目的,我需要在MySQL上生成"1213:Deadlock",以便UPDATE查询无法更新表.

我不是很确定如何造成僵局？

Answer 1

通过使用两个会话,有很多帖子.

https://dba.stackexchange.com/questions/309/code-to-simulate-deadlock

http://www.xaprb.com/blog/2006/08/08/how-to-deliberately-cause-a-deadlock-in-mysql/

从上面的第二篇文章复制的方法

首先,选择一个未使用的表名.我将使用test.innodb_deadlock_maker.以下是您需要执行的语句:

create table test.innodb_deadlock_maker(a int primary key) engine=innodb;
insert into test.innodb_deadlock_maker(a) values(0), (1);

现在设置表及其数据.接下来,在两个不同的连接上执行以下操作:

- 连接0

set transaction isolation level serializable;
start transaction;
select * from test.innodb_deadlock_maker where a = 0;
update test.innodb_deadlock_maker set a = 0 where a <> 0;

- 连接1

set transaction isolation level serializable;
start transaction;
select * from test.innodb_deadlock_maker where a = 1;
update test.innodb_deadlock_maker set a = 1 where a <> 1;

Answer 2

CREATE TABLE `table1` ( `id` INT NOT NULL AUTO_INCREMENT, `name` VARCHAR(255) NOT NULL, `marks` INT NOT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB;

INSERT INTO table1 (id, name, marks) VALUES (1, "abc", 5);

INSERT INTO table1 (id, name, marks) VALUES (2, "xyz", 1);

第一个窗口

BEGIN;
UPDATE table1 SET marks=marks-1 WHERE id=1; -- X lock acquired on 1

第二个窗口

再次更新

BEGIN;
UPDATE table1 SET marks=marks+1 WHERE id=2; -- X lock acquired on 2
UPDATE table1 SET marks=marks-1 WHERE id=1; -- LOCK WAIT!

第一个窗口（续）

UPDATE table1 SET marks=marks+1 WHERE id=2; -- DEADLOCK!
COMMIT;