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:

复制代码
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>

复制代码

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:

复制代码
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)

复制代码

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

复制代码
------------   
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

复制代码

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

复制代码
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)

复制代码

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:

复制代码
------------   
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 ;;

复制代码

为什么线程3当前执行的是一个select t3表操作,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:

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

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:

复制代码
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>

复制代码

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:http://blog.csdn.net/hw_libo/article/details/39080809

 

原文地址:https://www.cnblogs.com/duanxz/p/4394641.html

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