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| insert-wait-lock-mode-x-locks-gap-before-rec-insert-intention-vs-insert-wait-lock-mode-x-locks-gap-before-rec-insert-intention-holds-lock-mode-x-locks-gap-before-rec | ||
| === | ||
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| ## 死锁特征 | ||
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| 1. insert WAITING FOR lock_mode X locks gap before rec insert intention | ||
| 2. insert WAITING FOR lock_mode X locks gap before rec insert intention, HOLDS lock_mode X locks gap before rec | ||
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| ## 死锁日志 | ||
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| ``` | ||
| ------------------------ | ||
| LATEST DETECTED DEADLOCK | ||
| ------------------------ | ||
| 2017-09-11 14:51:03 7f78eaf25700 | ||
| *** (1) TRANSACTION: | ||
| TRANSACTION 462308535, ACTIVE 20 sec inserting | ||
| mysql tables in use 1, locked 1 | ||
| LOCK WAIT 3 lock struct(s), heap size 360, 2 row lock(s), undo log entries 1 | ||
| MySQL thread id 3584515, OS thread handle 0x7f78ea5f5700, query id 780258123 localhost root update | ||
| insert into t4(`kdt_id`, `admin_id`, `biz`, `role_id`, `shop_id`, `operator`, `operator_id`, `create_time`, `update_time`) | ||
| VALUES('18', '2', 'retail', '2', '0', '0', '0', CURRENT_TIMESTAMP, CURRENT_TIMESTAMP) | ||
| *** (1) WAITING FOR THIS LOCK TO BE GRANTED: | ||
| RECORD LOCKS space id 225 page no 4 n bits 72 index `uniq_kid_aid_biz_rid` of table `test`.`t4` trx id 462308535 lock_mode X locks gap before rec insert intention waiting | ||
| *** (2) TRANSACTION: | ||
| TRANSACTION 462308534, ACTIVE 29 sec inserting, thread declared inside InnoDB 5000 | ||
| mysql tables in use 1, locked 1 | ||
| 3 lock struct(s), heap size 360, 2 row lock(s), undo log entries 1 | ||
| MySQL thread id 3584572, OS thread handle 0x7f78eaf25700, query id 780258153 localhost root update | ||
| INSERT INTO t4(`kdt_id`, `admin_id`, `biz`, `role_id`, `shop_id`, `operator`, `operator_id`, `create_time`, `update_time`) | ||
| VALUES ('15', '1', 'retail', '2', '0', '0', '0', CURRENT_TIMESTAMP, CURRENT_TIMESTAMP) | ||
| *** (2) HOLDS THE LOCK(S): | ||
| RECORD LOCKS space id 225 page no 4 n bits 72 index `uniq_kid_aid_biz_rid` of table `test`.`t4` trx id 462308534 lock_mode X locks gap before rec | ||
| *** (2) WAITING FOR THIS LOCK TO BE GRANTED: | ||
| RECORD LOCKS space id 225 page no 4 n bits 72 index `uniq_kid_aid_biz_rid` of table `test`.`t4` trx id 462308534 lock_mode X locks gap before rec insert intention waiting | ||
| *** WE ROLL BACK TRANSACTION (2) | ||
| ``` | ||
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| ## 表结构 | ||
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| ```sql | ||
| CREATE TABLE `t4` ( | ||
| `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT , | ||
| `kdt_id` int(11) unsigned NOT NULL , | ||
| `admin_id` int(11) unsigned NOT NULL , | ||
| `biz` varchar(20) NOT NULL DEFAULT '1' , | ||
| `role_id` int(11) unsigned NOT NULL , | ||
| `shop_id` int(11) unsigned NOT NULL DEFAULT '0' , | ||
| `operator` varchar(20) NOT NULL DEFAULT '0' , | ||
| `operator_id` int(11) NOT NULL DEFAULT '0' , | ||
| `create_time` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间', | ||
| `update_time` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '更新时间', | ||
| PRIMARY KEY (`id`), | ||
| UNIQUE KEY `uniq_kid_aid_biz_rid` (`kdt_id`,`admin_id`,`role_id`,`biz`) | ||
| ) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8; | ||
| ``` | ||
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| 初始数据： | ||
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| ```sql | ||
| INSERT INTO `t4` (`id`, `kdt_id`, `admin_id`, `biz`, `role_id`, `shop_id`, `operator`, `operator_id`, `create_time`, `update_time`) | ||
| VALUES | ||
| (1,10,1,'retail',1,0,'0',0,'2017-05-09 15:55:26','2017-05-09 15:55:26'), | ||
| (2,20,1,'retail',1,0,'0',0,'2017-05-09 15:55:40','2017-05-09 15:55:40'), | ||
| (3,30,1,'retail',1,0,'0',0,'2017-05-09 15:55:55','2017-05-09 15:55:55'), | ||
| (4,40,1,'retail',1,0,'0',0,'2017-05-09 15:56:06','2017-05-09 15:56:06'), | ||
| (5,50,1,'retail',1,0,'0',0,'2017-05-09 15:56:16','2017-05-09 15:56:16'); | ||
| ``` | ||
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| ## 重现步骤 | ||
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| | Session 1 | Session 2 | | ||
| | --- | --- | | ||
| |delete from t4 where kdt_id = 15 and admin_id = 1 and biz = 'retail' and role_id = '1';|| | ||
| ||delete from t4 where kdt_id = 18 and admin_id = 2 and biz = 'retail' and role_id = '1';| | ||
| ||insert into t4(kdt_id, admin_id, biz, role_id, shop_id, operator, operator_id, create_time, update_time) VALUES('18', '2', 'retail', '2', '0', '0', '0', CURRENT_TIMESTAMP,CURRENT_TIMESTAMP);| | ||
| |INSERT INTO t4(kdt_id, admin_id, biz, role_id, shop_id, operator, operator_id, create_time, update_time) VALUES ('15', '1', 'retail', '2', '0', '0', '0', CURRENT_TIMESTAMP, CURRENT_TIMESTAMP);|.| | ||
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| ## 分析 | ||
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| 这个死锁和案例 1 一模一样，都是插入意向锁和 Gap 锁冲突导致的死锁。不过案例 1 插入的位置在 supremum record 上，这里插入的位置就是一个普通的 gap。 | ||
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| 当在 supremum record 上加锁时，`locks gap before rec` 会省略掉，所以这里的 `insert WAITING FOR lock_mode X locks gap before rec insert intention, HOLDS lock_mode X locks gap before rec` 和 案例 1 里的 `insert WAITING FOR lock_mode X insert intention waiting, HOLDS lock_mode X` 没任何区别，对这个死锁的分析参见案例 1 或参考链接，这里就不赘述了。 | ||
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| ## 参考 | ||
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| 1. [【MySQL】死锁案例之二](http://blog.itpub.net/22664653/viewspace-2145072/) |