时间:2020-10-19来源:www.pcxitongcheng.com作者:电脑系统城
正常情况下,死锁发生时,权重最小的连接将被kill并回滚。但是为了找出语句来优化,启用可启用死锁将死锁信息记录下来。
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#step 1:窗口一 mysql> start transaction ; mysql> update aa set name = 'aaa' where id = 1; #step 2:窗口二 mysql> start transaction ; mysql> update bb set name = 'bbb' where id = 1; #step 3:窗口一 mysql> update bb set name = 'bbb' ; |
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#step 4:窗口三 #是否自动提交 mysql> show variables like 'autocommit' ; + ---------------+-------+ | Variable_name | Value | + ---------------+-------+ | autocommit | ON | + ---------------+-------+ #查看当前连接 mysql> show processlist; mysql> show full processlist; mysql> SELECT * FROM INFORMATION_SCHEMA.PROCESSLIST; + ----+------+-----------+------+---------+------+-------+------------------+ | Id | User | Host | db | Command | Time | State | Info | + ----+------+-----------+------+---------+------+-------+------------------+ | 4 | root | localhost | test | Sleep | 244 | | NULL | | 5 | root | localhost | test | Sleep | 111 | | NULL | | 6 | root | localhost | NULL | Query | 0 | init | show processlist | + ----+------+-----------+------+---------+------+-------+------------------+ #查看当前正在被锁的事务(锁请求超时后则查不到) mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_LOCKS; + ------------------+-------------+-----------+-----------+-------------+-----------------+------------+-----------+----------+----------------+ | lock_id | lock_trx_id | lock_mode | lock_type | lock_table | lock_index | lock_space | lock_page | lock_rec | lock_data | + ------------------+-------------+-----------+-----------+-------------+-----------------+------------+-----------+----------+----------------+ | 130718495:65:3:4 | 130718495 | X | RECORD | `test`.`bb` | GEN_CLUST_INDEX | 65 | 3 | 4 | 0x000000000300 | | 130718496:65:3:4 | 130718496 | X | RECORD | `test`.`bb` | GEN_CLUST_INDEX | 65 | 3 | 4 | 0x000000000300 | + ------------------+-------------+-----------+-----------+-------------+-----------------+------------+-----------+----------+----------------+ #查看当前等待锁的事务(锁请求超时后则查不到) mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_LOCK_WAITS; + -------------------+-------------------+-----------------+------------------+ | requesting_trx_id | requested_lock_id | blocking_trx_id | blocking_lock_id | + -------------------+-------------------+-----------------+------------------+ | 130718499 | 130718499:65:3:4 | 130718500 | 130718500:65:3:4 | + -------------------+-------------------+-----------------+------------------+ #查看当前未提交的事务(如果死锁等待超时,事务可能还没有关闭) mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_TRX; + --------------------------------------------------------------------------------------------------------+ | trx_id | trx_state | trx_started | trx_requested_lock_id | trx_wait_started | trx_weight | + -----------+-----------+---------------------+-----------------------+---------------------+------------+ | 130718500 | RUNNING | 2018-03-12 09:28:10 | NULL | NULL | 3 | | 130718499 | LOCK WAIT | 2018-03-12 09:27:59 | 130718499:65:3:4 | 2018-03-12 09:32:48 | 5 | ========================================================================================================== | trx_mysql_thread_id | trx_query | trx_operation_state | trx_tables_in_use | + ---------------------+---------------------------------------+---------------------+-------------------+ | 4 | NULL | NULL | 0 | | 5 | update bb set name = 'bbb' | starting index read | 1 | ========================================================================================================= | trx_tables_locked | trx_lock_structs | trx_lock_memory_bytes | trx_rows_locked | trx_rows_modified | + -------------------+------------------+-----------------------+-----------------+-------------------+ | 0 | 2 | 360 | 3 | 1 | | 1 | 4 | 1184 | 4 | 1 | =========================================================================================================================== | trx_concurrency_tickets | trx_isolation_level | trx_unique_checks | trx_foreign_key_checks | trx_last_foreign_key_error | + -------------------------+---------------------+-------------------+------------------------+----------------------------+ | 0 | REPEATABLE READ | 1 | 1 | NULL | | 0 | REPEATABLE READ | 1 | 1 | NULL | =========================================================================================================================== | trx_adaptive_hash_latched | trx_adaptive_hash_timeout | trx_is_read_only | trx_autocommit_non_locking | + ---------------------------+---------------------------+------------------+----------------------------+ | 0 | 10000 | 0 | 0 | | 0 | 10000 | 0 | 0 | + ---------------------------+---------------------------+------------------+----------------------------+ #查看正在被访问的表 mysql> show OPEN TABLES where In_use > 0; + ----------+-------+--------+-------------+ | Database | Table | In_use | Name_locked | + ----------+-------+--------+-------------+ | test | bb | 1 | 0 | + ----------+-------+--------+-------------+ |
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#step 3:窗口一 (若第三步中锁请求太久,则出现锁超时而终止执行) mysql> update bb set name = 'bbb' ; ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction # "窗口一" 锁请求超时前,执行第五步,使死锁产生,则该连接 "窗口二" 执行终止, "窗口一" 顺利执行 #step 5:窗口二 mysql> update aa set name = 'aa' ; ERROR 1213 (40001): Deadlock found when trying to get lock; try restarting transaction |
查看最近一个死锁情况
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#查看最近一个死锁情况 mysql> SHOW ENGINE INNODB STATUS\G ; ............... ------------------------ LATEST DETECTED DEADLOCK ------------------------ 2018-03-12 11:01:06 7ffb4993a700 #发生时间 *** (1) TRANSACTION : #事务1 TRANSACTION 130718515, ACTIVE 19 sec starting index read mysql tables in use 1, locked 1 #正被访问的表 LOCK WAIT 4 lock struct(s), heap size 1184, 4 row lock(s), undo log entries 1 #影响行数 MySQL thread id 5, OS thread handle 0x7ffb498f8700, query id 205 localhost root updating #线程/连接host/用户 update bb set name = 'bb' #请求语句 *** (1) WAITING FOR THIS LOCK TO BE GRANTED: #等待以下资源 (锁定位置及锁模式) RECORD LOCKS space id 65 page no 3 n bits 72 index `GEN_CLUST_INDEX` of table `test`.`bb` trx id 130718515 lock_mode X waiting Record lock, heap no 5 PHYSICAL RECORD: n_fields 5; compact format; info bits 0 0: len 6; hex 000000000300; asc ;; 1: len 6; hex 000007ca9b34; asc 4;; 2: len 7; hex 1f000002092075; asc u;; 3: len 4; hex 80000001; asc ;; 4: len 2; hex 6262; asc bb;; *** (2) TRANSACTION : #事务2 TRANSACTION 130718516, ACTIVE 14 sec starting index read mysql tables in use 1, locked 1 4 lock struct(s), heap size 1184, 4 row lock(s), undo log entries 1 MySQL thread id 4, OS thread handle 0x7ffb4993a700, query id 206 localhost root updating update aa set name = 'aa' #请求语句 *** (2) HOLDS THE LOCK(S): #持有锁资源 RECORD LOCKS space id 65 page no 3 n bits 72 index `GEN_CLUST_INDEX` of table `test`.`bb` trx id 130718516 lock_mode X Record lock, heap no 1 PHYSICAL RECORD: n_fields 1; compact format; info bits 0 0: len 8; hex 73757072656d756d; asc supremum;; Record lock, heap no 3 PHYSICAL RECORD: n_fields 5; compact format; info bits 0 0: len 6; hex 000000000301; asc ;; 1: len 6; hex 000007ca9b17; asc ;; 2: len 7; hex 9000000144011e; asc D ;; 3: len 4; hex 80000002; asc ;; 4: len 2; hex 6262; asc bb;; Record lock, heap no 5 PHYSICAL RECORD: n_fields 5; compact format; info bits 0 0: len 6; hex 000000000300; asc ;; 1: len 6; hex 000007ca9b34; asc 4;; 2: len 7; hex 1f000002092075; asc u;; 3: len 4; hex 80000001; asc ;; 4: len 2; hex 6262; asc bb;; *** (2) WAITING FOR THIS LOCK TO BE GRANTED: RECORD LOCKS space id 64 page no 3 n bits 80 index `GEN_CLUST_INDEX` of table `test`.`aa` trx id 130718516 lock_mode X waiting Record lock, heap no 7 PHYSICAL RECORD: n_fields 5; compact format; info bits 0 0: len 6; hex 000000000200; asc ;; 1: len 6; hex 000007ca9b33; asc 3;; 2: len 7; hex 1e000001d53057; asc 0W;; 3: len 4; hex 80000001; asc ;; 4: len 2; hex 6161; asc aa;; *** WE ROLL BACK TRANSACTION (2) ............... |
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#死锁记录只记录最近一个死锁信息,若要将每个死锁信息都保存到错误日志,启用以下参数: mysql> show variables like 'innodb_print_all_deadlocks' ; + ----------------------------+-------+ | Variable_name | Value | + ----------------------------+-------+ | innodb_print_all_deadlocks | OFF | + ----------------------------+-------+ #上面 【step 3:窗口一】若一直请求不到资源,默认50秒则出现锁等待超时。 mysql> show variables like 'innodb_lock_wait_timeout' ; + --------------------------+-------+ | Variable_name | Value | + --------------------------+-------+ | innodb_lock_wait_timeout | 50 | + --------------------------+-------+ ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction #设置全局变量 锁等待超时为60秒(新的连接生效) #mysql> set session innodb_lock_wait_timeout=50; mysql> set global innodb_lock_wait_timeout=60; #上面测试中,当事务中的某个语句超时只回滚该语句,事务的完整性属于被破坏了。为了回滚这个事务,启用以下参数: mysql> show variables like 'innodb_rollback_on_timeout' ; + ----------------------------+-------+ | Variable_name | Value | + ----------------------------+-------+ | innodb_rollback_on_timeout | OFF | + ----------------------------+-------+ |
最终参数设置如下:(重启服务重新连接测试)
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[mysqld] log-error =/var/log/mysqld3306.log innodb_lock_wait_timeout=60 #锁请求超时时间(秒) innodb_rollback_on_timeout = 1 #事务中某个语句锁请求超时将回滚真个事务 innodb_print_all_deadlocks = 1 #死锁都保存到错误日志 |
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#若手动删除堵塞会话,删除 Command= 'Sleep' 、无State、无Info、trx_weight 权重最小的。 show processlist; SELECT trx_mysql_thread_id,trx_state,trx_started,trx_weight FROM INFORMATION_SCHEMA.INNODB_TRX; |
总结
到此这篇关于MySQL死锁检查处理的文章就介绍到这了
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