• mysql 查看死锁和去除死锁

    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_locksG;
    
Empty     set, 1 warning (0.00 sec)
    

    ERROR:
    
No query specified
    

    mysql> show processlistG;
    
     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 warningsG
    
     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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  • 原文地址：https://www.cnblogs.com/jpfss/p/11491526.html
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