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《Mysql实例查找原始mysql死锁id实例详解》要点：
本文介绍了Mysql实例查找原始mysql死锁id实例详解，希望对您有用。如果有疑问，可以联系我们。
导读：在mysql死锁问题发生时,一般是找到原始的锁id,然后杀掉那个线程,但是众多线程,可怎么找到引起死锁的线程id呢? mysql 发展到现在,已...
MYSQL应用在mysql死锁问题发生时,可怎么找到引起死锁的线程id呢?
mysql 发展到现在,已经非常强大了,这个问题很好解决. 直接从数据字典连查找.
MYSQL应用这里有个演示实例,大家做参考：
线程a,用来锁定某些记录,假设这个线程一直没提交,或忘掉提交了,那么就一直存在,但是数据里面显示的只是sleep状态.
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MYSQL应用mysql> set @@autocommit=0;
query ok,0 rows affected (0.00 sec)
MYSQL应用mysql> use test;
reading table information for completion of table and column names
you can turn off this feature to get a quicker startup with -a
MYSQL应用database changed
mysql> show tables;
+----------------+
| tables_in_test |
+----------------+
| demo_test |
| t3 |
+----------------+
2 rows in set (0.00 sec)
MYSQL应用mysql> select * from t3;
+----+--------+--------+------------+----+----+----+
| id | fname | lname | birthday | c1 | c2 | c3 |
+----+--------+--------+------------+----+----+----+
| 19 | lily19 | lucy19 | 2013-04-18 | 19 | 0 | 0 |
| 20 | lily20 | lucy20 | 2013-03-13 | 20 | 0 | 0 |
+----+--------+--------+------------+----+----+----+
2 rows in set (0.00 sec)
MYSQL应用mysql> update t3 set birthday = '2022-02-23' where id = 19;
query ok,1 row affected (0.00 sec)
rows matched: 1 changed: 1 warnings: 0
MYSQL应用mysql> select connection_id();
+-----------------+
| connection_id() |
+-----------------+
| 16 |
+-----------------+
1 row in set (0.00 sec)
MYSQL应用线程b,用来进行普通的更新,但是遇到问题了,此时不知道是哪个线程把这行记录给锁定了?
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MYSQL应用mysql> use test;
reading table information for completion of table and column names
you can turn off this feature to get a quicker startup with -a
MYSQL应用database changed
mysql> select @@autocommit;
+--------------+
| @@autocommit |
+--------------+
| 1 |
+--------------+
1 row in set (0.00 sec)
mysql> update t3 set birthday='2018-01-03' where id = 19;
error 1205 (hy000): lock wait timeout exceeded; try restarting transaction
mysql> select connection_id();
+-----------------+
| connection_id() |
+-----------------+
| 17 |
+-----------------+
1 row in set (0.00 sec)
MYSQL应用mysql> show processlist;
+----+------+-----------+------+---------+------+-------+------------------+
| id | user | host | db | command | time | state | info |
+----+------+-----------+------+---------+------+-------+------------------+
| 10 | root | localhost | null | sleep | 1540 | | null |
| 11 | root | localhost | null | sleep | 722 | | null |
| 16 | root | localhost | test | sleep | 424 | | null |
| 17 | root | localhost | test | query | 0 | init | show processlist |
| 18 | root | localhost | null | sleep | 5 | | null |
+----+------+-----------+------+---------+------+-------+------------------+
5 rows in set (0.00 sec)
MYSQL应用mysql> show engine innodb statusg
------------
transactions
------------
trx id counter 189327
purge done for trx's n:o < 189323 undo n:o < 0 state: running but idle
history list length 343
list of transactions for each session:
---transaction 0,not started
mysql thread id 11,os thread handle 0x7f70a0c98700,query id 994 localhost root init
show engine innodb status
---transaction 189326,active 2 sec starting index read
mysql tables in use 1,locked 1
lock wait 2 lock struct(s),heap size 376,1 row lock(s)
mysql thread id 17,os thread handle 0x7f70a0bd5700,query id 993 localhost root updating
update t3 set birthday='2018-01-03' where id = 19
------- trx has been waiting 2 sec for this lock to be granted:
record locks space id 529 page no 3 n bits 72 index `primary` of table `test`.`t3` trx id 189326 lock_mode x waiting
record lock,heap no 2 physical record: n_fields 9; compact format; info bits 0
?0: len 2; hex 3139; asc 19;;
?1: len 6; hex 00000002e38c; asc ;;
?2: len 7; hex 7e00000d2827c9; asc ~ (' ;;
?3: len 6; hex 6c696c793139; asc lily19;;
?4: len 6; hex 6c7563793139; asc lucy19;;
?5: len 3; hex 8fcc57; asc w;;
?6: len 4; hex 80000013; asc ;;
?7: len 4; hex 80000000; asc ;;
?8: len 4; hex 80000000; asc ;;
------------------
---transaction 189324,active 641 sec
2 lock struct(s),3 row lock(s),undo log entries 1
mysql thread id 16,os thread handle 0x7f70a0b94700,query id 985 localhost root cleaning up
trx read view will not see trx with id >= 189325,sees < 189325
MYSQL应用上面的信息很繁多,也看不清楚到底哪里是哪里.
MYSQL应用不过现在,只要从数据字典里面拿出来这部分信息就ok了.
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mysql> select * from information_schema.innodb_trxg
*************************** 1. row ***************************
??????????????????? trx_id: 189324
???????????????? trx_state: running
?????????????? trx_started: 2013-04-18 17:48:14
???? trx_requested_lock_id: null
????????? trx_wait_started: null
??????????????? trx_weight: 3
?????? trx_mysql_thread_id: 16
???????????????? 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: 3
???????? 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
????????? trx_is_read_only: 0
trx_autocommit_non_locking: 0
1 row in set (0.01 sec)
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MYSQL应用原来是线程16忘掉commit了. （编辑：李大同）
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