Mysql必读查找MySQL线程中死锁的ID的方法

《Mysql必读查找MySQL线程中死锁的ID的方法》要点：
本文介绍了Mysql必读查找MySQL线程中死锁的ID的方法，希望对您有用。如果有疑问，可以联系我们。

?如果遇到死锁了,怎么办理呢?找到原始的锁ID,然后KILL掉一直持有的那个线程就可以了,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,已经非常强大了,这个问题很好办理. 直接从数据字典连查找.MYSQL教程

我们来演示下.MYSQL教程

线程A,我们用来锁定某些记录,假设这个线程一直没提交,或者忘掉提交了. 那么就一直存在,但是数据里面显示的只是SLEEP状态.MYSQL教程

mysql> set @@autocommit=0;
Query OK,0 rows affected (0.00 sec)
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
Database changed
mysql> show tables;
+―――――-+
| Tables_in_test |
+―――――-+
| demo_test   |
| t3       |
+―――――-+
2 rows in set (0.00 sec)
mysql> select * from t3;
+―-+――C+――C+――――+―-+―-+―-+
| id | fname | lname | birthday  | c1 | c2 | c3 |
+―-+――C+――C+――――+―-+―-+―-+
| 19 | lily19 | lucy19 | 2013-04-18 | 19 | 0 | 0 |
| 20 | lily20 | lucy20 | 2013-03-13 | 20 | 0 | 0 |
+―-+――C+――C+――――+―-+―-+―-+
2 rows in set (0.00 sec)
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> select connection_id();
+―――――C+
| connection_id() |
+―――――C+
|       16 |
+―――――C+
1 row in set (0.00 sec)
mysql> 

线程B,我们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?MYSQL教程

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
Database changed
mysql> select @@autocommit;
+――――C+
| @@autocommit |
+――――C+
|      1 |
+――――C+
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();
+―――――C+
| connection_id() |
+―――――C+
|       17 |
+―――――C+
1 row in set (0.00 sec)
mysql> show processlist;
+―-+――+―――C+――+―――+――+――-+――――――+
| Id | User | Host   | db  | Command | Time | State | Info       |
+―-+――+―――C+――+―――+――+――-+――――――+
| 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       |
+―-+――+―――C+――+―――+――+――-+――――――+
5 rows in set (0.00 sec)
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

上面的信息很繁多,也看不清楚到底哪里是哪里.MYSQL教程

不过现在,我们只要从数据字典里面拿出来这部分信息就OK了.MYSQL教程

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)
mysql> 

本来是线程16忘掉COMMIT了.
MYSQL教程

编程之家PHP培训学院每天发布《Mysql必读查找MySQL线程中死锁的ID的方法》等实战技能，PHP、MYSQL、LINUX、APP、JS,CSS全面培养人才。

（编辑：李大同）

【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容!