投稿
  1. 首页
  2. mysql

mysql查看死锁与去除死锁示例详解

code • 2022-5-14 • mysql • 阅读 62

mysql查看死锁与去除死锁示例详解,第1张

mysql查看死锁与去除死锁示例详解

1、查询进程

show processlist

2、 查询到相对应的进程，然后 kill id

验证（kill后再看是否还有锁）

2、查询是否锁表

show OPEN TABLES where In_use > 0;

示例：

新建一个会话执行如下的显示锁示例

LOCK TABLES account_data.account READ;
SELECT SLEEP(160);
UNLOCK TABLES account_data.account;

另开启一个会话检查锁表情况：

mysql> show OPEN TABLES where In_use > 0;
+--------------+---------+--------+-------------+
| Database  | Table | In_use | Name_locked |
+--------------+---------+--------+-------------+
| account_data | account |  1 |   0 |
+--------------+---------+--------+-------------+
1 row in set (0.00 sec)

mysql> select * from information_schema.innodb_locks\G;
Empty set, 1 warning (0.00 sec)

ERROR: 
No query specified

mysql> show processlist\G;
*************************** 1. row ***************************
  Id: 5
 User: root
 Host: 192.168.0.206:64294
  db: NULL
Command: Sleep
 Time: 4051
 State: 
 Info: NULL
*************************** 2. row ***************************
  Id: 8
 User: root
 Host: 192.168.0.206:64297
  db: NULL
Command: Sleep
 Time: 4042
 State: 
 Info: NULL
*************************** 3. row ***************************
  Id: 10
 User: root
 Host: localhost
  db: NULL
Command: Query
 Time: 0
 State: starting
 Info: show processlist
*************************** 4. row ***************************
  Id: 19
 User: root
 Host: 192.168.0.206:54603
  db: account_data
Command: Sleep
 Time: 245
 State: 
 Info: NULL
*************************** 5. row ***************************
  Id: 20
 User: root
 Host: 192.168.0.206:54604
  db: information_schema
Command: Query
 Time: 20
 State: User sleep
 Info: select sleep(160)
5 rows in set (0.00 sec)

ERROR: 
No query specified

mysql>

3、在5.5中，information_schema 库中增加了三个关于锁的表（innoDB引擎）：

innodb_trx ## 当前运行的所有事务

innodb_locks ## 当前出现的锁

innodb_lock_waits ## 锁等待的对应关系

先来看一下这三张表结构：

[email protected] : information_schema 13:28:38> desc innodb_locks;
+————-+———————+——+—–+———+——-+
| Field  | Type    | Null | Key | Default | Extra |
+————-+———————+——+—–+———+——-+
| lock_id  | varchar(81)   | NO |  |   |  |#锁ID
| lock_trx_id | varchar(18)   | NO |  |   |  |#拥有锁的事务ID
| lock_mode | varchar(32)   | NO |  |   |  |#锁模式
| lock_type | varchar(32)   | NO |  |   |  |#锁类型
| lock_table | varchar(1024)  | NO |  |   |  |#被锁的表
| lock_index | varchar(1024)  | YES |  | NULL |  |#被锁的索引
| lock_space | bigint(21) unsigned | YES |  | NULL |  |#被锁的表空间号
| lock_page | bigint(21) unsigned | YES |  | NULL |  |#被锁的页号
| lock_rec | bigint(21) unsigned | YES |  | NULL |  |#被锁的记录号
| lock_data | varchar(8192)  | YES |  | NULL |  |#被锁的数据
+————-+———————+——+—–+———+——-+
10 rows in set (0.00 sec)
 
[email protected] : information_schema 13:28:56> desc innodb_lock_waits;
+——————-+————-+——+—–+———+——-+
| Field    | Type  | Null | Key | Default | Extra |
+——————-+————-+——+—–+———+——-+
| requesting_trx_id | varchar(18) | NO |  |   |  |#请求锁的事务ID
| requested_lock_id | varchar(81) | NO |  |   |  |#请求锁的锁ID
| blocking_trx_id | varchar(18) | NO |  |   |  |#当前拥有锁的事务ID
| blocking_lock_id | varchar(81) | NO |  |   |  |#当前拥有锁的锁ID
+——————-+————-+——+—–+———+——-+
4 rows in set (0.00 sec)
 
[email protected] : information_schema 13:29:05> desc innodb_trx ;
+—————————-+———————+——+—–+———————+——-+
| Field      | Type    | Null | Key | Default    | Extra |
+—————————-+———————+——+—–+———————+——-+
| trx_id      | varchar(18)   | NO |  |      |  |#事务ID
| trx_state     | varchar(13)   | NO |  |      |  |#事务状态：
| trx_started    | datetime   | NO |  | 0000-00-00 00:00:00 |  |#事务开始时间；
| trx_requested_lock_id  | varchar(81)   | YES |  | NULL    |  |#innodb_locks.lock_id
| trx_wait_started   | datetime   | YES |  | NULL    |  |#事务开始等待的时间
| trx_weight     | bigint(21) unsigned | NO |  | 0     |  |#
| trx_mysql_thread_id  | bigint(21) unsigned | NO |  | 0     |  |#事务线程ID
| trx_query     | varchar(1024)  | YES |  | NULL    |  |#具体SQL语句
| trx_operation_state  | varchar(64)   | YES |  | NULL    |  |#事务当前 *** 作状态
| trx_tables_in_use   | bigint(21) unsigned | NO |  | 0     |  |#事务中有多少个表被使用
| trx_tables_locked   | bigint(21) unsigned | NO |  | 0     |  |#事务拥有多少个锁
| trx_lock_structs   | bigint(21) unsigned | NO |  | 0     |  |#
| trx_lock_memory_bytes  | bigint(21) unsigned | NO |  | 0     |  |#事务锁住的内存大小（B）
| trx_rows_locked   | bigint(21) unsigned | NO |  | 0     |  |#事务锁住的行数
| trx_rows_modified   | bigint(21) unsigned | NO |  | 0     |  |#事务更改的行数
| trx_concurrency_tickets | bigint(21) unsigned | NO |  | 0     |  |#事务并发票数
| trx_isolation_level  | varchar(16)   | NO |  |      |  |#事务隔离级别
| trx_unique_checks   | int(1)    | NO |  | 0     |  |#是否唯一性检查
| trx_foreign_key_checks  | int(1)    | NO |  | 0     |  |#是否外键检查
| trx_last_foreign_key_error | varchar(256)  | YES |  | NULL    |  |#最后的外键错误
| trx_adaptive_hash_latched | int(1)    | NO |  | 0     |  |#
| trx_adaptive_hash_timeout | bigint(21) unsigned | NO |  | 0     |  |#
+—————————-+———————+——+—–+———————+——-+
22 rows in set (0.01 sec)

查看正在锁的事务

SELECT * FROM INFORMATION_SCHEMA.INNODB_LOCKS;

查看等待锁的事务

SELECT * FROM INFORMATION_SCHEMA.INNODB_LOCK_WAITS;

查看锁阻塞线程信息

3.1 使用show processlist查看

3.2 直接使用show engine innodb status查看

------------ 
TRANSACTIONS 
------------ 
Trx id counter 4131 
Purge done for trx's n:o < 4119 undo n:o < 0 state: running but idle 
History list length 126 
LIST OF TRANSACTIONS FOR EACH SESSION: 
---TRANSACTION 0, not started 
MySQL thread id 2, OS thread handle 0x7f953ffff700, query id 115 localhost root init 
show engine innodb status 
---TRANSACTION 4130, ACTIVE 41 sec starting index read 
mysql tables in use 1, locked 1 
LOCK WAIT 2 lock struct(s), heap size 360, 1 row lock(s) 
MySQL thread id 4, OS thread handle 0x7f953ff9d700, query id 112 localhost root updating 
delete from emp where empno=7788 
------- TRX HAS BEEN WAITING 41 SEC FOR THIS LOCK TO BE GRANTED: ## 等待了41s 
RECORD LOCKS space id 16 page no 3 n bits 88 index `PRIMARY` of table `test`.`emp` trx id 4130 lock_mode X locks rec but not gap waiting 
Record lock, heap no 9 PHYSICAL RECORD: n_fields 10; compact format; info bits 0 ## 线程4在等待往test.emp中的主键上加X锁，page num=3 
 0: len 4; hex 80001e6c; asc l;; 
 1: len 6; hex 000000001018; asc  ;; 
 2: len 7; hex 91000001420084; asc  B ;; 
 3: len 5; hex 53434f5454; asc SCOTT;; 
 4: len 7; hex 414e414c595354; asc ANALYST;; 
 5: len 4; hex 80001d8e; asc  ;; 
 6: len 4; hex 208794f0; asc  ;; 
 7: len 4; hex 80000bb8; asc  ;; 
 8: SQL NULL; 
 9: len 4; hex 80000014; asc  ;; 
 
------------------ 
---TRANSACTION 4129, ACTIVE 45 sec starting index read 
mysql tables in use 1, locked 1 
LOCK WAIT 2 lock struct(s), heap size 360, 1 row lock(s) 
MySQL thread id 7, OS thread handle 0x7f953ff6c700, query id 111 localhost root updating 
update emp set sal=3500 where empno=7788 
------- TRX HAS BEEN WAITING 45 SEC FOR THIS LOCK TO BE GRANTED: ## 等待了45s 
RECORD LOCKS space id 16 page no 3 n bits 88 index `PRIMARY` of table `test`.`emp` trx id 4129 lock_mode X locks rec but not gap waiting 
Record lock, heap no 9 PHYSICAL RECORD: n_fields 10; compact format; info bits 0 ## 线程7在等待往test.emp中的主键上加X锁，page num=3 
 0: len 4; hex 80001e6c; asc l;; 
 1: len 6; hex 000000001018; asc  ;; 
 2: len 7; hex 91000001420084; asc  B ;; 
 3: len 5; hex 53434f5454; asc SCOTT;; 
 4: len 7; hex 414e414c595354; asc ANALYST;; 
 5: len 4; hex 80001d8e; asc  ;; 
 6: len 4; hex 208794f0; asc  ;; 
 7: len 4; hex 80000bb8; asc  ;; 
 8: SQL NULL; 
 9: len 4; hex 80000014; asc  ;; 
 
------------------ 
---TRANSACTION 4128, ACTIVE 51 sec 
2 lock struct(s), heap size 360, 1 row lock(s) 
MySQL thread id 3, OS thread handle 0x7f953ffce700, query id 110 localhost root cleaning up

我们知道，主要根因还是thread=3引起的，但从innodb status中却无法分析得到这个结果。

从上面来看，线程4和线程7都在等待往test.emp中的主键上加X锁，page num=3，但是线程7等待的时间为45s，而线程4等待的时间为41s，是较线程7之后申请的锁，所以可以判断是线程7阻塞了线程4。至于线程7为什么出现等待，这里分析不到根因。

3.3 使用mysqladmin debug查看

# mysqladmin -S /tmp/mysql3306.sock debug

然后在error日志中，会看到：

Thread database.table_name   Locked/Waiting  Lock_type 
 
 
3  test.t3      Locked - read   Low priority read lock 
7  test.emp     Locked - write  High priority write lock

这种方法中，能找到线程ID=3和7是阻塞者，但还是不太准确，判断不出来线程7也是被线程ID=3阻塞的。

3.4 使用innodb_lock_monitor来获取阻塞锁线程

MySQL [test]> CREATE TABLE innodb_lock_monitor (a INT) ENGINE=INNODB; ## 随便在一个数据库中创建这个表，就会打开lock monitor 
Query OK, 0 rows affected, 1 warning (0.07 sec) 
 
MySQL [test]> show warnings\G 
*************************** 1. row *************************** 
 Level: Warning 
 Code: 131 
Message: Using the table name innodb_lock_monitor to enable diagnostic output is deprecated and may be removed in future releases. Use INFORMATION_SCHEMA or PERFORMANCE_SCHEMA tables or SET GLOBAL innodb_status_output=ON. 
1 row in set (0.00 sec)

说明：这个在5.6中有一个warning，但不影响使用。

然后再使用show engine innodb status查看：

------------ 
TRANSACTIONS 
------------ 
Trx id counter 4667 
Purge done for trx's n:o < 4659 undo n:o < 0 state: running but idle 
History list length 138 
LIST OF TRANSACTIONS FOR EACH SESSION: 
---TRANSACTION 0, not started 
MySQL thread id 9, OS thread handle 0x7f813c5f7700, query id 152 localhost root init 
show engine innodb status 
---TRANSACTION 4663, ACTIVE 78 sec starting index read 
mysql tables in use 1, locked 1 
LOCK WAIT 2 lock struct(s), heap size 360, 1 row lock(s) 
MySQL thread id 4, OS thread handle 0x7f813c628700, query id 149 localhost root updating 
delete from emp where empno=7788 
------- TRX HAS BEEN WAITING 78 SEC FOR THIS LOCK TO BE GRANTED: ## 等待了78s 
RECORD LOCKS space id 16 page no 3 n bits 88 index `PRIMARY` of table `test`.`emp` trx id 4663 lock_mode X locks rec but not gap waiting 
Record lock, heap no 9 PHYSICAL RECORD: n_fields 10; compact format; info bits 0 ## 线程4在等待往test.emp中的主键上加X锁，page num=3 
 0: len 4; hex 80001e6c; asc l;; 
 1: len 6; hex 000000001018; asc  ;; 
 2: len 7; hex 91000001420084; asc  B ;; 
 3: len 5; hex 53434f5454; asc SCOTT;; 
 4: len 7; hex 414e414c595354; asc ANALYST;; 
 5: len 4; hex 80001d8e; asc  ;; 
 6: len 4; hex 208794f0; asc  ;; 
 7: len 4; hex 80000bb8; asc  ;; 
 8: SQL NULL; 
 9: len 4; hex 80000014; asc  ;; 
 
------------------ 
TABLE LOCK table `test`.`emp` trx id 4663 lock mode IX ## 在给主键行上加X锁之前，先要在表上加意向锁IX 
RECORD LOCKS space id 16 page no 3 n bits 88 index `PRIMARY` of table `test`.`emp` trx id 4663 lock_mode X locks rec but not gap waiting 
Record lock, heap no 9 PHYSICAL RECORD: n_fields 10; compact format; info bits 0 
 0: len 4; hex 80001e6c; asc l;; 
 1: len 6; hex 000000001018; asc  ;; 
 2: len 7; hex 91000001420084; asc  B ;; 
 3: len 5; hex 53434f5454; asc SCOTT;; 
 4: len 7; hex 414e414c595354; asc ANALYST;; 
 5: len 4; hex 80001d8e; asc  ;; 
 6: len 4; hex 208794f0; asc  ;; 
 7: len 4; hex 80000bb8; asc  ;; 
 8: SQL NULL; 
 9: len 4; hex 80000014; asc  ;; 
 
---TRANSACTION 4662, ACTIVE 81 sec starting index read 
mysql tables in use 1, locked 1 
LOCK WAIT 2 lock struct(s), heap size 360, 1 row lock(s) 
MySQL thread id 7, OS thread handle 0x7f813c5c6700, query id 148 localhost root updating 
update emp set sal=3500 where empno=7788 
------- TRX HAS BEEN WAITING 81 SEC FOR THIS LOCK TO BE GRANTED: ## 等待了81s 
RECORD LOCKS space id 16 page no 3 n bits 88 index `PRIMARY` of table `test`.`emp` trx id 4662 lock_mode X locks rec but not gap waiting 
Record lock, heap no 9 PHYSICAL RECORD: n_fields 10; compact format; info bits 0 ## 线程7在等待往test.emp中的主键上加X锁，page num=3 
 0: len 4; hex 80001e6c; asc l;; 
 1: len 6; hex 000000001018; asc  ;; 
 2: len 7; hex 91000001420084; asc  B ;; 
 3: len 5; hex 53434f5454; asc SCOTT;; 
 4: len 7; hex 414e414c595354; asc ANALYST;; 
 5: len 4; hex 80001d8e; asc  ;; 
 6: len 4; hex 208794f0; asc  ;; 
 7: len 4; hex 80000bb8; asc  ;; 
 8: SQL NULL; 
 9: len 4; hex 80000014; asc  ;; 
 
------------------ 
TABLE LOCK table `test`.`emp` trx id 4662 lock mode IX ## 在给主键行上加X锁之前，先要在表上加意向锁IX 
RECORD LOCKS space id 16 page no 3 n bits 88 index `PRIMARY` of table `test`.`emp` trx id 4662 lock_mode X locks rec but not gap waiting 
Record lock, heap no 9 PHYSICAL RECORD: n_fields 10; compact format; info bits 0 
 0: len 4; hex 80001e6c; asc l;; 
 1: len 6; hex 000000001018; asc  ;; 
 2: len 7; hex 91000001420084; asc  B ;; 
 3: len 5; hex 53434f5454; asc SCOTT;; 
 4: len 7; hex 414e414c595354; asc ANALYST;; 
 5: len 4; hex 80001d8e; asc  ;; 
 6: len 4; hex 208794f0; asc  ;; 
 7: len 4; hex 80000bb8; asc  ;; 
 8: SQL NULL; 
 9: len 4; hex 80000014; asc  ;; 
 
---TRANSACTION 4615, ACTIVE 1579 sec, thread declared inside InnoDB 1222 
mysql tables in use 2, locked 0 
2 lock struct(s), heap size 360, 1 row lock(s) 
MySQL thread id 3, OS thread handle 0x7f813c659700, query id 147 localhost root Sending data 
select count(*) from t3 a,t3 b ## 这是线程3当前正在执行的SQL 
Trx read view will not see trx with id >= 4662, sees < 4659 
TABLE LOCK table `test`.`emp` trx id 4615 lock mode IX ## 线程3中正在拥有表上的意向IX锁，并且有test.emp表上主键的行级X锁，page num=3 
RECORD LOCKS space id 16 page no 3 n bits 88 index `PRIMARY` of table `test`.`emp` trx id 4615 lock_mode X locks rec but not gap 
Record lock, heap no 9 PHYSICAL RECORD: n_fields 10; compact format; info bits 0 
 0: len 4; hex 80001e6c; asc l;; 
 1: len 6; hex 000000001018; asc  ;; 
 2: len 7; hex 91000001420084; asc  B ;; 
 3: len 5; hex 53434f5454; asc SCOTT;; 
 4: len 7; hex 414e414c595354; asc ANALYST;; 
 5: len 4; hex 80001d8e; asc  ;; 
 6: len 4; hex 208794f0; asc  ;; 
 7: len 4; hex 80000bb8; asc  ;; 
 8: SQL NULL; 
 9: len 4; hex 80000014; asc  ;;

为什么线程3当前执行的是一个select t3表 *** 作，但却锁住了test.emp表上page num=3？

有可能是线程3之前对test.emp表的 *** 作事务没有及时提交导致。

所以得出：线程3阻塞了线程7，而线程7又阻塞了线程4，所以根因就是线程3，让线程3尽快提交或是kill掉即可。

3.5、 查看表锁的情况：

mysql> show status like 'table%';
+----------------------------+---------+
| Variable_name | Value |
+----------------------------+---------+
| Table_locks_immediate | 100 |
| Table_locks_waited | 11 |
+----------------------------+---------+

3.6、查看InnoDB_row_lock状态变量来分析系统上的行锁的争夺情况：

mysql> show status like 'InnoDB_row_lock%';
+-------------------------------+--------+
| Variable_name     | Value |
+-------------------------------+--------+
| Innodb_row_lock_current_waits | 0  |
| Innodb_row_lock_time   | 159372 |
| Innodb_row_lock_time_avg  | 39843 |
| Innodb_row_lock_time_max  | 51154 |
| Innodb_row_lock_waits   | 4  |
+-------------------------------+--------+
5 rows in set (0.01 sec)

mysql>

4. 结论

在分析innodb中锁阻塞时，几种方法的对比情况：

（1）使用show processlist查看不靠谱；

（2）直接使用show engine innodb status查看，无法判断到问题的根因；

（3）使用mysqladmin debug查看，能看到所有产生锁的线程，但无法判断哪个才是根因；

（4）开启innodb_lock_monitor后，再使用show engine innodb status查看，能够找到锁阻塞的根因。

参考：https://www.jb51.net/article/201222.htm

到此这篇关于mysql查看死锁与去除死锁的文章就介绍到这了,更多相关mysql查看死锁与去除死锁内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家！

欢迎分享，转载请注明来源：内存溢出

原文地址: https://outofmemory.cn/sjk/889074.html

赞 (0)
打赏 微信扫一扫 微信扫一扫 支付宝扫一扫 支付宝扫一扫
code code 管理员组
0 0
上一篇 2022-05-14
下一篇 2022-05-14

发表评论

登录后才能评论

评论列表（0条）

保存