mysql unique 锁_mysql 行锁排查

2024-05-15 12:11:21

mysql 锁表: 隔离级别使用RR: mysql> SELECT @@GLOBAL.tx_isolation, @@tx_isolation; +-----------------------+-----------------+ | @@GLOBAL.tx_isolation | @@tx_isolation | +-----------------------+-----------------+ | REPEATABLE-READ | REPEATABLE-READ SESSION A: mysql> show full processlist; +----+------+-----------+------+---------+------+-------+-----------------------+ | Id | User | Host | db | Command | Time | State | Info | +----+------+-----------+------+---------+------+-------+-----------------------+ | 1 | root | localhost | NULL | Query | 0 | init | show full processlist | +----+------+-----------+------+---------+------+-------+-----------------------+ 1 row in set (0.02 sec) mysql> insert into test values(1,'a'); Query OK, 1 row affected (0.00 sec) mysql> select * from test; +------+------+ | id | name | +------+------+ | 1 | a | +------+------+ 1 row in set (0.00 sec) mysql> show full processlist; +----+------+-----------+--------+---------+------+-------+-----------------------+ | Id | User | Host | db | Command | Time | State | Info | +----+------+-----------+--------+---------+------+-------+-----------------------+ | 1 | root | localhost | DEVOPS | Query | 0 | init | show full processlist | | 2 | root | localhost | DEVOPS | Sleep | 8 | | NULL | +----+------+-----------+--------+---------+------+-------+-----------------------+ 2 rows in set (0.00 sec) mysql> update test set name='b' where id=1; Query OK, 1 row affected (0.00 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> show full processlist; +----+------+-----------+--------+---------+------+-------+-----------------------+ | Id | User | Host | db | Command | Time | State | Info | +----+------+-----------+--------+---------+------+-------+-----------------------+ | 1 | root | localhost | DEVOPS | Query | 0 | init | show full processlist | | 2 | root | localhost | DEVOPS | Sleep | 34 | | NULL | +----+------+-----------+--------+---------+------+-------+-----------------------+ 2 rows in set (0.00 sec) SESSION B: 此时HANG： mysql>mysql> update test set name='c100' where id=1; SESSION B的信息: mysql> show full processlist; +----+------+-----------+--------+---------+------+----------+----------------------------------------+ | Id | User | Host | db | Command | Time | State | Info | +----+------+-----------+--------+---------+------+----------+----------------------------------------+ | 1 | root | localhost | DEVOPS | Query | 0 | init | show full processlist | | 2 | root | localhost | DEVOPS | Query | 2 | updating | update test set name='c100' where id=1 | +----+------+-----------+--------+---------+------+----------+----------------------------------------+ 2 rows in set (0.00 sec) 此时SESION B也就是Id=2 被堵塞,一直在更新模拟 Id=1获取锁: mysql> show full processlist; +----+------+----------------------+------+---------+------+-------+-----------------------+ | Id | User | Host | db | Command | Time | State | Info | +----+------+----------------------+------+---------+------+-------+-----------------------+ | 7 | root | 115.236.160.82:53073 | NULL | Sleep | 184 | | NULL | | 8 | root | 115.236.160.82:53074 | NULL | Sleep | 184 | | NULL | | 9 | root | localhost | NULL | Query | 0 | init | show full processlist | +----+------+----------------------+------+---------+------+-------+-----------------------+ 3 rows in set (0.00 sec) mysql> select * from test; +------+------+ | id | name | +------+------+ | 1 | b | | 2 | b | | 2 | b | +------+------+ 3 rows in set (0.00 sec) SELECT r.trx_state wating_trx_state, r.trx_id waiting_trx_id, r.trx_mysql_thread_Id waiting_thread, r.trx_query waiting_query, b.trx_state blocking_trx_state, b.trx_id blocking_trx_id, b.trx_mysql_thread_id blocking_thread, 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 # wating_trx_state, waiting_trx_id, waiting_thread, waiting_query, blocking_trx_state, blocking_trx_id, blocking_thread, blocking_query 'LOCK WAIT', '2332', '10', 'update test set name='aabbcc100' where id=1', 'RUNNING', '2331', '9', NULL mysql> desc information_schema.innodb_lock_waits -> ; +-------------------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------------------+-------------+------+-----+---------+-------+ | requesting_trx_id | varchar(18) | NO | | | | | requested_lock_id | varchar(81) | NO | | | | | blocking_trx_id | varchar(18) | NO | | | | | blocking_lock_id | varchar(81) | NO | | | | +-------------------+-------------+------+-----+---------+-------+ 4 rows in set (0.00 sec) REQUESTING_TRX_ID ID of the requesting transaction. 请求事务的ID REQUESTED_LOCK_ID ID of the lock for which a transaction is waiting. Details about the lock can be found by joining with INNODB_LOCKS on LOCK_ID. 事务在等待的lockid ,详细的信息可以关联 INNODB_LOCKS on LOCK_ID BLOCKING_TRX_ID ID of the blocking transaction. blocking 事务的 ID 持有者 BLOCKING_LOCK_ID ID of a lock held by a transaction blocking another transaction from proceeding. Details about the lock can be found by joining with INNODB_LOCKS on LOCK_ID. 一个事务持有的lock ID 阻塞其他事务处理 mysql> desc information_schema.innodb_trx -> ; +----------------------------+---------------------+------+-----+---------------------+-------+ | Field | Type | Null | Key | Default | Extra | +----------------------------+---------------------+------+-----+---------------------+-------+ | trx_id | varchar(18) | NO | | | | | trx_state | varchar(13) | NO | | | | | trx_started | datetime | NO | | 0000-00-00 00:00:00 | | | trx_requested_lock_id | varchar(81) | YES | | NULL | | | trx_wait_started | datetime | YES | | NULL | | | trx_weight | bigint(21) unsigned | NO | | 0 | | | trx_mysql_thread_id | bigint(21) unsigned | NO | | 0 | | | trx_query | varchar(1024) | YES | | NULL | | | 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 (0.00 sec) TRX_ID 唯一的事务ID号, InnoDB内部使用.( 在MySQL 5.6开始, 那些IDs不是被创建用于事务的,是只读的和非堵塞的 TRX_WEIGHT 一个事务的权重, 反映(但是不是必须的准确的计数) 被改变的行和被事务锁定的行。为了解决死锁, InnoDB 选择最小权重的事务作为 victim来回滚。事务改变非事务表是被认为比其他权重高, 不管更改的数目和锁住的行数 TRX_STATE 事务执行状态, RUNNING,LOCK WAIT, 回滚或者提交 TRX_STARTED Transaction start time. 事务开始时间 TRX_REQUESTED_LOCK_ID LOCK 事务ID 是当前等待(如果 TRX_STATE 是lock,否则为空) TRX_WAIT_STARTED 当交易开始等待lock(如果TRX_STATE 是LOCK WAIT,否则NULL) TRX_MYSQL_THREAD_ID MySQL thread ID,可以用于关联PROCESSLIST 的ID mysql> show full processlist; +----+------+-----------+--------+---------+------+-------+-----------------------+ | Id | User | Host | db | Command | Time | State | Info | +----+------+-----------+--------+---------+------+-------+-----------------------+ | 1 | root | localhost | DEVOPS | Sleep | 6 | | NULL | | 2 | root | localhost | DEVOPS | Query | 0 | init | show full processlist | +----+------+-----------+--------+---------+------+-------+-----------------------+ 见章节 14.13.2.3.1 ,潜在的不一致的PROCESSLIST数据 TRX_QUERY 通过事务执行的SQL TRX_OPERATION_STATE 事务的当前操作,或者为NULL TRX_TABLES_IN_USE Innodb表当前被使用来处理当前事务的SQL的表的数量 TRX_TABLES_LOCKED InnoDB表当前SQL语句有行锁的表的数量。因为这些是row locks, 不是表锁,表仍旧可以被读取和被多个事务写,尽管有些行被锁定。 TRX_LOCK_STRUCT 事务保留的锁的数目 TRX_LOCK_MEMORY_BYTES 这个事务的lock 结构在内存里占用的大小 TRX_ROWS_LOCKED 这个事务的锁定的大概记录的行数, 该值可能包括标记为删除的记录物理上是存在的但是对于事务不可见 TRX_ROWS_MODIFIED 在该事务中修改和插入的数目 TRX_CONCURRENCY_TICKETS 这个值表明当前事务可以做多少事情在被交换出去之前, 通过 innodb_concurrency_tickets 选择指定 TRX_ISOLATION_LEVEL 当前事务的隔离级别 TRX_UNIQUE_CHECKS 是否 unique checks 被启用或者关闭对于当前的事务, 它们可以在一个批量数据加载时关闭

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