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记一次处理MySql锁等待(Lock wait timeout exceeded)

2015-12-18 08:02 656 查看
摘要 最近项目部署到新环境中,新环境中总报
Lock wait timeout exceeded 。

目录[-]

MySQL 5.5 -- innodb_lock_wait 锁 等待

环境

MySQL5.5

现象

A.数据更新或新增后数据经常自动回滚。

B.表操作总报 Lock wait timeout exceeded 并长时间无反应

解决方法

A.应急方法:show processlist; kill掉出现问题的进程

B.根治方法:select * from innodb_trx 查看有是哪些事务占据了表资源。

C.我的方法:设置MySQL锁等待超时 innodb_lock_wait_timeout=50 ,autocommit=on

该类问题导致原因

据我分析,Mysql的 InnoDB存储引擎是支持事务的,事务开启后没有被主动Commit。导致该资源被长期占用,其他事务在抢占该资源时,因上一个事务的锁而导致抢占失败!因此出现 Lock wait timeout exceeded

接下来是转载的内容

转载:http://blog.sina.com.cn/s/blog_6bb63c9e0100s7cb.html


MySQL 5.5 -- innodb_lock_wait 锁 等待

记得以前,当出现:ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction,

要解决是一件麻烦的事情 ;

特别是当一个SQL执行完了,但未COMMIT,后面的SQL想要执行就是被锁,超时结束;

DBA光从数据库无法着手找出源头是哪个SQL锁住了;

有时候看看show engine innodb status , 并结合 show full processlist; 能暂时解决问题;但一直不能精确定位;

在5.5中,information_schema 库中增加了三个关于锁的表(MEMORY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

看到这个就非常激动 ; 这可是解决了一个大麻烦,先来看一下表结构

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)

下面我们来动手看看数据吧:

##建立测试数据:

use test;

create table tx1

(id int primary key ,

c1 varchar(20),

c2 varchar(30))

engine=innodb default charset = utf8 ;

insert into tx1 values

(1,'aaaa','aaaaa2'),

(2,'bbbb','bbbbb2'),

(3,'cccc','ccccc2');

commit;

###产生事务;

### Session1

start transaction;

update tx1 set c1='heyf',c2='heyf' where id =3 ;

## 产生事务,在innodb_trx就有数据 ;

root@127.0.0.1 :
information_schema 13:38:21> select * from innodb_trx G

*************************** 1. row ***************************

trx_id: 3669D82

trx_state: RUNNING

trx_started: 2010-12-24 13:38:06

trx_requested_lock_id: NULL

trx_wait_started: NULL

trx_weight: 3

trx_mysql_thread_id: 2344

trx_query: NULL

trx_operation_state: NULL

trx_tables_in_use: 0

trx_tables_locked: 0

trx_lock_structs: 2

trx_lock_memory_bytes: 376

trx_rows_locked: 1

trx_rows_modified: 1

trx_concurrency_tickets: 0

trx_isolation_level: REPEATABLE READ

trx_unique_checks: 1

trx_foreign_key_checks: 1

trx_last_foreign_key_error: NULL

trx_adaptive_hash_latched: 0

trx_adaptive_hash_timeout: 10000

1 row in set (0.00 sec)

### 由于没有产生锁等待,下面两个表没有数据 ;

root@127.0.0.1 :
information_schema 13:38:31> select * from innodb_lock_waits G

Empty set (0.00 sec)

root@127.0.0.1 :
information_schema 13:38:57> select * from innodb_locks G

Empty set (0.00 sec)

#### 产生锁等待

#### session 2

start transaction;

update tx1 set c1='heyfffff',c2='heyffffff' where id =3 ;

root@127.0.0.1 :
information_schema 13:39:01> select * from innodb_trx G

*************************** 1. row ***************************

trx_id: 3669D83 ##第2个事务

trx_state: LOCK WAIT ## 处于等待状态

trx_started: 2010-12-24 13:40:07

trx_requested_lock_id: 3669D83:49:3:4 ##请求的锁ID

trx_wait_started: 2010-12-24 13:40:07

trx_weight: 2

trx_mysql_thread_id: 2346 ##线程 ID

trx_query: update tx1 set c1='heyfffff',c2='heyffffff' where id =3

trx_operation_state: starting index read

trx_tables_in_use: 1 ##需要用到1个表

trx_tables_locked: 1 ##有1个表被锁

trx_lock_structs: 2

trx_lock_memory_bytes: 376

trx_rows_locked: 1

trx_rows_modified: 0

trx_concurrency_tickets: 0

trx_isolation_level: REPEATABLE READ

trx_unique_checks: 1

trx_foreign_key_checks: 1

trx_last_foreign_key_error: NULL

trx_adaptive_hash_latched: 0

trx_adaptive_hash_timeout: 10000

*************************** 2. row ***************************

trx_id: 3669D82 ##第1个事务

trx_state: RUNNING

trx_started: 2010-12-24 13:38:06

trx_requested_lock_id: NULL

trx_wait_started: NULL

trx_weight: 3

trx_mysql_thread_id: 2344

trx_query: NULL

trx_operation_state: NULL

trx_tables_in_use: 0

trx_tables_locked: 0

trx_lock_structs: 2

trx_lock_memory_bytes: 376

trx_rows_locked: 1

trx_rows_modified: 1

trx_concurrency_tickets: 0

trx_isolation_level: REPEATABLE READ

trx_unique_checks: 1

trx_foreign_key_checks: 1

trx_last_foreign_key_error: NULL

trx_adaptive_hash_latched: 0

trx_adaptive_hash_timeout: 10000

2 rows in set (0.00 sec)

root@127.0.0.1 :
information_schema 13:40:12> select * from innodb_locks G

*************************** 1. row ***************************

lock_id: 3669D83:49:3:4 ## 第2个事务需要的锁

lock_trx_id: 3669D83

lock_mode: X

lock_type: RECORD

lock_table: `test`.`tx1`

lock_index: `PRIMARY`

lock_space: 49

lock_page: 3

lock_rec: 4

lock_data: 3

*************************** 2. row ***************************

lock_id: 3669D82:49:3:4 ## 第1个事务需要的锁

lock_trx_id: 3669D82

lock_mode: X

lock_type: RECORD

lock_table: `test`.`tx1`

lock_index: `PRIMARY`

lock_space: 49

lock_page: 3

lock_rec: 4

lock_data: 3

2 rows in set (0.00 sec)

root@127.0.0.1 :
information_schema 13:40:15> select * from innodb_lock_waits G

*************************** 1. row ***************************

requesting_trx_id: 3669D83 ## 请求锁的事务

requested_lock_id: 3669D83:49:3:4 ## 请求锁的锁ID

blocking_trx_id:
3669D82 ## 拥有锁的事务

blocking_lock_id: 3669D82:49:3:4
## 拥有锁的锁ID

1 row in set (0.00 sec)
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