mysql 鎖表: 隔離級別使用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: 此時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) 此時SESION B也就是Id=2 被堵塞,一直在更新 模擬 Id=1獲取鎖: 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. 請求事務的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. 事務在等待的lockid ,詳細的信息可以關聯 INNODB_LOCKS on LOCK_ID BLOCKING_TRX_ID ID of the blocking transaction. blocking 事務的 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. 一個事務持有的lock ID 阻塞其他事務處理 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 唯一的事務ID號, InnoDB內部使用.( 在MySQL 5.6開始, 那些IDs不是被創建用于事務的,是只讀的和非堵塞的 TRX_WEIGHT 一個事務的權重, 反映(但是不是必須的準確的計數) 被改變的行和被事務鎖定的行。 為了解決死鎖, InnoDB 選擇最小權重的事務作為 victim來回滾。 事務 改變非事務表是被認為比其他權重高, 不管更改的數目和鎖住的行數 TRX_STATE 事務執行狀態, RUNNING,LOCK WAIT, 回滾或者提交 TRX_STARTED Transaction start time. 事務開始時間 TRX_REQUESTED_LOCK_ID LOCK 事務ID 是當前等待(如果 TRX_STATE 是lock,否則為空) TRX_WAIT_STARTED 當交易開始等待lock(如果TRX_STATE 是LOCK WAIT,否則NULL) TRX_MYSQL_THREAD_ID MySQL thread ID,可以用于關聯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 | +----+------+-----------+--------+---------+------+-------+-----------------------+ 見章節 14.13.2.3.1 ,潛在的不一致的PROCESSLIST數據 TRX_QUERY 通過事務執行的SQL TRX_OPERATION_STATE 事務的當前操作,或者為NULL TRX_TABLES_IN_USE Innodb表當前被使用來處理當前事務的SQL的表的數量 TRX_TABLES_LOCKED InnoDB表當前SQL語句有行鎖的表的數量。 因為這些是row locks, 不是表鎖,表仍舊可以被讀取和被多個事務寫,盡管有些行被鎖定。 TRX_LOCK_STRUCT 事務保留的鎖的數目 TRX_LOCK_MEMORY_BYTES 這個事務的lock 結構在內存里占用的大小 TRX_ROWS_LOCKED 這個事務的鎖定的大概記錄的行數, 該值可能包括標記為刪除的記錄 物理上是存在的 但是對于事務不可見 TRX_ROWS_MODIFIED 在該事務中修改和插入的數目 TRX_CONCURRENCY_TICKETS 這個值表明 當前事務可以做多少事情在被交換出去之前, 通過 innodb_concurrency_tickets 選擇指定 TRX_ISOLATION_LEVEL 當前事務的隔離級別 TRX_UNIQUE_CHECKS 是否 unique checks 被啟用或者關閉 對于當前的事務, 它們可以在一個批量數據加載時關閉

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