mysql:5.5
mysql> show variables like '%iso%';
 +---------------+-----------------+
 | Variable_name | Value           |
 +---------------+-----------------+
 | tx_isolation  | REPEATABLE-READ |innodb引擎

场景:
mysql> select * from t1;
 +------+------+---------------------+ 

 | c1   | c2   | c3                  | 

 +------+------+---------------------+ 

 |    1 |    2 | 2017-11-08 10:24:19 | 

 |    3 |    4 | 2017-11-08 10:24:26 | 

 |    5 |    6 | 2017-11-08 10:24:32 | 

 +------+------+---------------------+ 

 3 rows in set (0.00 sec) 


 mysql> select * from t2; 

 +------+------+---------------------+ 

 | c1   | c2   | c3                  | 

 +------+------+---------------------+ 

 |    5 |    6 | 2017-11-08 10:25:10 | 

 |    7 |    8 | 2017-11-08 10:25:18 | 

 +------+------+---------------------+ 



 mysql> show create table t1\G 

 *************************** 1. row *************************** 

        Table: t1 

 Create Table: CREATE TABLE `t1` ( 

   `c1` int(11) DEFAULT NULL, 

   `c2` int(11) DEFAULT NULL, 

   `c3` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00', 

   KEY `idx01` (`c3`) 

 ) ENGINE=InnoDB DEFAULT CHARSET=utf8 

 1 row in set (0.00 sec) 



 mysql> show create table t2\G 

 *************************** 1. row *************************** 

        Table: t2 

 Create Table: CREATE TABLE `t2` ( 

   `c1` int(11) DEFAULT NULL, 

   `c2` int(11) DEFAULT NULL, 

   `c3` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00', 

   KEY `idx01` (`c3`) 

 ) ENGINE=InnoDB DEFAULT CHARSET=utf8 

 1 row in set (0.00 sec) 


 mysql> begin; 

 Query OK, 0 rows affected (0.00 sec) 


 mysql> update t1,(select c1,sum(c2) 'c2' from t2 where c3 between '2017-11-08 00:00:00' and '2017-11-08 23:59:59' group by c1) as tmp2 

     -> set t1.c2=tmp2.c2 

     -> where t1.c1=tmp2.c1; 

 Query OK, 0 rows affected (0.00 sec) 

 Rows matched: 1  Changed: 0  Warnings: 0 



 卡住，发生阻塞. 

 会话二: 

 mysql> begin; 

 Query OK, 0 rows affected (0.00 sec) 


 mysql> insert into t2 values(10,11,now()); 


 解决方式： 

 在执行时间较长的会话加入隔离级别设置，比如在会话1中加入:set tx_isolation='READ-COMMITTED'(会话级别);