• 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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