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;

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;

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 specifiedmysql> show processlist\G;*************************** 1. row ***************************  Id: 5 User: root Host: 192.168.0.206:64294  db: NULLCommand: Sleep Time: 4051 State:  Info: NULL*************************** 2. row ***************************  Id: 8 User: root Host: 192.168.0.206:64297  db: NULLCommand: Sleep Time: 4042 State:  Info: NULL*************************** 3. row ***************************  Id: 10 User: root Host: localhost  db: NULLCommand: Query Time: 0 State: starting Info: show processlist*************************** 4. row ***************************  Id: 19 User: root Host: 192.168.0.206:54603  db: account_dataCommand: Sleep Time: 245 State:  Info: NULL*************************** 5. row ***************************  Id: 20 User: root Host: 192.168.0.206:54604  db: information_schemaCommand: Query Time: 20 State: User sleep Info: select sleep(160)5 rows in set (0.00 sec)ERROR: No query specifiedmysql>

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：

root@127.0.0.1 : 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) root@127.0.0.1 : 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) root@127.0.0.1 : 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    |  |#事务当前操作状态| 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)

SELECT * FROM INFORMATION_SCHEMA.INNODB_LOCKS;

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

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

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

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)

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  ;;

有可能是线程3之前对test.emp表的操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 |+----------------------------+---------+

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>

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

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