怎么使用mysql5.6informationschema定位事务锁信息
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引子 mysql数据库在运行期间,随着业务体量增加及并发会话陡升,可能随时会出现各种性能问题。其中比较常见的一种 现象,某一天公司业务人员或客户反馈说某个业务模板突然卡住了,或者开发同学说某个SQL语句不能继续运行了。 mysql 5.6引入的information_schema数据库,可以完美解决上述的问题。它提供一系列的数据视图或表,便于 诊断及分析数据库的各种各样的性能问题,对于运维同学真是大大福利。本文主要介绍information_schema与锁 相关的几个表,快速定位是哪些会话或事务导致事务操作不能持续。 概念 information-schema是一个内置的数据库,通过一系列的表,比如:锁方面的表,字符集相关的表,插件相关的 表,进程相关的表,视图相关的表,不一而足。运维人员可以通过不同的表的信息,有助于分析各种各样的性能问题 。 当然,可以结合另一个数据库performance_schema数据库,更方便诊断数据库的各种各样的性能问题甚至故障 情形。 mysql information-schema官方手册,请查阅如下链接 https://dev.mysql.com/doc/refman/5.6/en/information-schema.html mysql锁相关官方手册,请查阅如下链接 https://dev.mysql.com/doc/refman/5.6/en/innodb-locking-transaction-model.html information-schema实践 1,数据库版本 [root@standbygtid ~]# mysql -V mysql Ver 14.14 Distrib 5.6.25, for Linux (x86_64) using EditLine wrapper 2,登陆mysql [root@standbygtid ~]# mysql -uroot -psystem 3,显示事务及锁相关的表 (注:有ORACLE从业经验的同学,类似于oracle 动态性能视图v$session及locked_objects) mysql> use information_schema; 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> mysql> show tables like 'INNODB%'; +----------------------------------------+ | Tables_in_information_schema (INNODB%) | +----------------------------------------+ | INNODB_LOCKS | | INNODB_TRX | 略 | INNODB_LOCK_WAITS | +----------------------------------------+ 28 rows in set (0.00 sec) 4,上述几个表的含义 ---锁表 (注:锁是什么,就是你需要某种资源,但此时由人家占着,你需要等待,这就是一种锁,锁的目标就是维护数据一致性) mysql> desc innodb_locks; +-------------+---------------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------------+---------------------+------+-----+---------+-------+ | lock_id | varchar(81) | NO | | | | 锁编号 | lock_trx_id | varchar(18) | NO | | | | 锁所属事务 | lock_mode | varchar(32) | NO | | | | 锁模式 | lock_type | varchar(32) | NO | | | | 锁类型 | lock_table | varchar(1024) | NO | | | | 锁对应表 | lock_index | varchar(1024) | YES | | NULL | | 锁对应索引 | lock_space | bigint(21) unsigned | YES | | NULL | | 锁空间 | lock_page | bigint(21) unsigned | YES | | NULL | | 锁对应的页面 | lock_rec | bigint(21) unsigned | YES | | NULL | | 锁对应的表记录 | lock_data | varchar(8192) | YES | | NULL | | +-------------+---------------------+------+-----+---------+-------+ 10 rows in set (0.00 sec) ---事务表 mysql> desc innodb_trx; +----------------------------+---------------------+------+-----+---------------------+-------+ | Field | Type | Null | Key | Default | Extra | +----------------------------+---------------------+------+-----+---------------------+-------+ | trx_id | varchar(18) | NO | | | | 事务编号 | 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 | | 事务请求锁编号 | trx_wait_started | datetime | YES | | NULL | | 事务等待开始时间 | trx_weight | bigint(21) unsigned | NO | | 0 | | 事务权重 | trx_mysql_thread_id | bigint(21) unsigned | NO | | 0 | | 事务对应的线程 | trx_query | varchar(1024) | YES | | NULL | | 事务所属的SQL语句 | trx_operation_state | varchar(64) | YES | | NULL | | | trx_tables_in_use | bigint(21) unsigned | NO | | 0 | | | trx_tables_locked | bigint(21) unsigned | NO | | 0 | | | trx_lock_structs | bigint(21) unsigned | NO | | 0 | | | trx_lock_memory_bytes | bigint(21) unsigned | NO | | 0 | | | trx_rows_locked | bigint(21) unsigned | NO | | 0 | | | trx_rows_modified | bigint(21) unsigned | NO | | 0 | | | trx_concurrency_tickets | bigint(21) unsigned | NO | | 0 | | | trx_isolation_level | varchar(16) | NO | | | | | trx_unique_checks | int(1) | NO | | 0 | | | trx_foreign_key_checks | int(1) | NO | | 0 | | | trx_last_foreign_key_error | varchar(256) | YES | | NULL | | | trx_adaptive_hash_latched | int(1) | NO | | 0 | | | trx_adaptive_hash_timeout | bigint(21) unsigned | NO | | 0 | | | trx_is_read_only | int(1) | NO | | 0 | | | trx_autocommit_non_locking | int(1) | NO | | 0 | | +----------------------------+---------------------+------+-----+---------------------+-------+ 24 rows in set (0.01 sec) ---锁等待表 mysql> desc innodb_lock_waits; +-------------------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------------------+-------------+------+-----+---------+-------+ | requesting_trx_id | varchar(18) | NO | | | | 请求锁事务编号 | requested_lock_id | varchar(81) | NO | | | | 请求锁编号 | blocking_trx_id | varchar(18) | NO | | | | 持锁事务编号 | blocking_lock_id | varchar(81) | NO | | | | 持锁 锁编号 +-------------------+-------------+------+-----+---------+-------+ 4 rows in set (0.00 sec) 5,为了模拟事务,关闭自动提交 (注:生产系统一定要关闭,防止不小心在生产系统产生误操作无法撤回) mysql> show variables like '%autocommit%'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | autocommit | ON | +---------------+-------+ 1 row in set (0.00 sec) mysql> set autocommit=off; Query OK, 0 rows affected (0.01 sec) mysql> show variables like '%autocommit%'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | autocommit | OFF | +---------------+-------+ 1 row in set (0.00 sec) 6,产生一个事务 --新开一个登陆会话,不提交 (注:如果一提交,则事务马上消失) mysql> update zxydb.t_go set a=3; Query OK, 16778789 rows affected (1 min 0.91 sec) Rows matched: 25168933 Changed: 16778789 Warnings: 0 --在另一会话查看线程信息 mysql> show processlist; +----+------+-----------+--------------------+---------+------+----------+---------------------------+ | Id | User | Host | db | Command | Time | State | Info | +----+------+-----------+--------------------+---------+------+----------+---------------------------+ | 28 | root | localhost | information_schema | Query | 19 | updating | update zxydb.t_go set a=3 | | 29 | root | localhost | NULL | Query | 0 | init | show processlist | +----+------+-----------+--------------------+---------+------+----------+---------------------------+ 2 rows in set (0.00 sec) --查看事务表 mysql> select * from information_schema.innodb_trx\G; *************************** 1. row *************************** trx_id: 3996 trx_state: RUNNING 事务运行状态 trx_started: 2019-11-06 05:46:18 事务开始的时间 trx_requested_lock_id: NULL trx_wait_started: NULL trx_weight: 25224373 trx_mysql_thread_id: 28 事务所属的线程,对应上述的show processlist之id列 trx_query: NULL trx_operation_state: NULL trx_tables_in_use: 0 trx_tables_locked: 0 trx_lock_structs: 55440 trx_lock_memory_bytes: 8042024 trx_rows_locked: 25224372 trx_rows_modified: 25168933 事务影响的表记录数 trx_concurrency_tickets: 0 trx_isolation_level: REPEATABLE READ 事务隔离级别 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 (0.03 sec) ERROR: No query specified --由上可见如果没有竞争资源时,不会产生锁 (注:产生锁的前提条件是必须在2个会话以上,当然不包括mysql自身产生的bug) mysql> select * from information_schema.innodb_locks\G; Empty set (0.04 sec) ERROR: No query specified --没有竞资源,当然也不会产生锁等待 mysql> select * from information_schema.innodb_lock_waits\G; Empty set (0.03 sec) ERROR: No query specified 7,再开启一个新事务会话 (注:更新上述同一个表的记录,即会产生锁等待,因为需要更新同一个表的记录资源) mysql> set autocommit=off; Query OK, 0 rows affected (0.01 sec) mysql> insert into zxydb.t_go select 3,3; ----可见产生了锁信息 mysql> select * from information_schema.innodb_locks\G; *************************** 1. row *************************** lock_id: 3997:6:55726:1 lock_trx_id: 3997 lock_mode: X 锁模式,x表示排它锁,s表示共享锁 lock_type: RECORD lock_table: `zxydb`.`t_go` 锁定表 lock_index: GEN_CLUST_INDEX GEN_CLUST_INDEX表示表级锁 lock_space: 6 lock_page: 55726 lock_rec: 1 lock_data: supremum pseudo-record *************************** 2. row *************************** lock_id: 3996:6:55726:1 lock_trx_id: 3996 lock_mode: X lock_type: RECORD lock_table: `zxydb`.`t_go` lock_index: GEN_CLUST_INDEX lock_space: 6 lock_page: 55726 lock_rec: 1 lock_data: supremum pseudo-record 2 rows in set (0.03 sec) ERROR: No query specified ---同时也产生锁等待信息 mysql> select * from information_schema.innodb_lock_waits\G; *************************** 1. row *************************** requesting_trx_id: 3997 请求锁的事务id requested_lock_id: 3997:6:55726:1 blocking_trx_id: 3996 持锁的事务id blocking_lock_id: 3996:6:55726:1 1 row in set (0.03 sec) ERROR: No query specified 8,为了方便监控锁等待的信息,可以编写下述SQL语句 ---获取持锁会话及等待锁会话更详细的信息 select trx.trx_mysql_thread_id, trx.trx_id, trx.trx_state, trx.trx_started, trx.trx_query, locks.lock_type, locks.lock_table, lock_waits.requesting_trx_id, lock_waits.blocking_trx_id from information_schema.innodb_trx trx inner join information_schema.innodb_locks locks on trx.trx_id=locks.lock_trx_id inner join information_schema.innodb_lock_waits lock_waits on trx.trx_id=lock_waits.requesting_trx_id inner join information_schema.innodb_lock_waits lock_waits on trx.trx_id=lock_waits.blocking_trx_id; 可知,3997事务是等待锁,而3996是持锁,所以如果你想让3997可以继续工作,有几种方法: 1,继续等待3996事务完成 2,完成3996事务 3,杀死3996事务(操作语句为:kill 28,28为事务所属的线程) +---------------------+--------+-----------+---------------------+-----------------------------------+-----------+----------------+-------------------+-----------------+ | trx_mysql_thread_id | trx_id | trx_state | trx_started | trx_query | lock_type | lock_table | requesting_trx_id | blocking_trx_id | +---------------------+--------+-----------+---------------------+-----------------------------------+-----------+----------------+-------------------+-----------------+ | 30 | 3997 | LOCK WAIT | 2019-11-06 05:51:04 | insert into zxydb.t_go select 3,3 | RECORD | `zxydb`.`t_go` | 3997 | 3996 | | 28 | 3996 | RUNNING | 2019-11-06 05:46:18 | NULL | RECORD | `zxydb`.`t_go` | NULL | NULL | +---------------------+--------+-----------+---------------------+-----------------------------------+-----------+----------------+-------------------+-----------------+ 2 rows in set (0.04 sec)
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文章名称:怎么使用mysql5.6informationschema定位事务锁信息
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