Question

我们有一个Symphony2 Web应用程序，并使用Doctrine作为ORM。

后端我们将AWS RDS MySQL与InnoDB引擎结合使用。

SHOW VARIABLES LIKE "%version%";
innodb_version  5.6.22
protocol_version    10
slave_type_conversions  
version 5.6.22-log
version_comment MySQL Community Server (GPL)
version_compile_machine x86_64
version_compile_os  Linux

我们可以通过反复单击提交按钮来触发数据库服务器上的意外死锁。这是我们收到的错误消息的一部分：

------------------------
LATEST DETECTED DEADLOCK
------------------------


2015-06-16 07:13:17 2aebdd723700
*** (1) TRANSACTION:
TRANSACTION 2009024, ACTIVE 0 sec starting index read
mysql tables in use 1, locked 1
LOCK WAIT 3 lock struct(s), heap size 360, 1 row lock(s), undo log entries 2
MySQL thread id 11125, OS thread handle 0x2aebdd6e2700, query id 1666530 172.31.26.135 db_name updating
UPDATE cmp_item SET title = 'Contract of employment 456', date_modification = '2015-06-16 09:14:37' WHERE id = 64297
*** (1) WAITING FOR THIS LOCK TO BE GRANTED:
RECORD LOCKS space id 15706 page no 10780 n bits 80 index `PRIMARY` of table `db_name`.`cmp_item` trx id 2009024 lock_mode X locks rec but not gap waiting
Record lock, heap no 14 PHYSICAL RECORD: n_fields 102; compact format; info bits 0


*** (2) TRANSACTION:
TRANSACTION 2009010, ACTIVE 0 sec starting index read
mysql tables in use 1, locked 1
12 lock struct(s), heap size 2936, 7 row lock(s), undo log entries 4
MySQL thread id 11124, OS thread handle 0x2aebdd723700, query id 1666536 172.31.26.135 db_name updating
UPDATE cmp_item SET title = 'Contract of employment 456', date_modification = '2015-06-16 09:14:38' WHERE id = 64297
*** (2) HOLDS THE LOCK(S):
RECORD LOCKS space id 15706 page no 10780 n bits 80 index `PRIMARY` of table `db_name`.`cmp_item` trx id 2009010 lock mode S locks rec but not gap
Record lock, heap no 14 PHYSICAL RECORD: n_fields 102; compact format; info bits 0

我们不明白为什么会出现这种僵局。

为什么会这样，我们怎样才能避免这种情况？

Answer 1

死锁通常（总是？）需要在两个（或更多）线程中的每个线程中执行多个语句。据推测，您的两个更新前面都有一些其他语句，这些语句锁定了各种表中的各行。仔细查看整个D:>ssh -T git@git.company.com Hi my_user! You've successfully authenticated, but GitHub does not provide shell access. D:\>git clone git@git.company.com:myOrg/leaf.git Cloning into 'leaf'... Permission denied (publickey). fatal: Could not read from remote repository. Please make sure you have the correct access rights and the repository exists. ... BEGIN。把它们展示给我们。

为什么这个InnoDB死锁发生在一个简单的UPDATE？

1 个答案: