mysql事务锁等待时间

获取表锁信息

SELECT
r.trx_id waiting_trx_id,
r.trx_mysql_thread_id waiting_thread,
TIMESTAMPDIFF(
SECOND,
r.trx_wait_started,
CURRENT_TIMESTAMP
) wait_time,
r.trx_query waiting_query,
l.lock_table waiting_table_lock,
b.trx_id blocking_trx_id,
b.trx_mysql_thread_id blocking_thread,
SUBSTRING(
p. HOST,
1,
INSTR(p. HOST, ':') - 1
) blocking_host,
SUBSTRING(p. HOST, INSTR(p. HOST, ':') + 1) blocking_port,

IF (p.COMMAND = 'Sleep', p.TIME, 0) idel_in_trx,
b.trx_query blocking_query
FROM
information_schema.INNODB_LOCK_WAITS w
INNER JOIN information_schema.INNODB_TRX b ON b.trx_id = w.blocking_trx_id
INNER JOIN information_schema.INNODB_TRX r ON r.trx_id = w.requesting_trx_id
INNER JOIN information_schema.INNODB_LOCKS l ON w.requested_lock_id = l.lock_id
LEFT JOIN information_schema. PROCESSLIST p ON p.ID = b.trx_mysql_thread_id
ORDER BY
wait_time DESC;

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：

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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)

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下面我们来动手看看数据吧：

##建立测试数据：

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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;

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###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

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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)

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### 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

复制代码

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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哈哈，有了以上这些信息，以下问题就迎刃而解啦。当前有哪些事务在等待锁？ 这些锁需要锁哪些表，锁哪些索引，锁哪些记录和值？处于等待状态的相关SQL是什么？在等待哪些事务完成 ？拥有当前锁的SQL是什么？

我想这些SQL对DBA来说不难吧？