解决CentOS服务器：mysql 1040 too many connections问题（亲测有用）
方法一：
1、mysql -u root -p 回车输入密码进入mysql
[root@root ~]# mysql -u root -p Enter password: Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 135 Server version: 5.1.73 Source distribution Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql>
2、查看现在MYSQL的最大链接数，执行：show variables like “max_connections”;
mysql> show variables like "max_connections"; +-----------------+-------+ | Variable_name | Value | +-----------------+-------+ | max_connections | 151 | +-----------------+-------+ 1 row in set (0.01 sec)
我们这里可以看到：MYSQL的最大链接数才151，
3、修改MYSQL的最大链接数，执行：set GLOBAL max_connections=10000;
mysql> set GLOBAL max_connections=10000; mysql>
4、再执行：show variables like “max_connections”;看看MYSQL的最大链接数有没有修改成功：
mysql> show variables like "max_connections"; +-----------------+-------+ | Variable_name | Value | +-----------------+-------+ | max_connections | 10000 | +-----------------+-------+ 1 row in set (0.01 sec)
我们这里可以看到：MYSQL的最大链接数才10000了，退出就可以了
5、exit退出，这种方法弊端就是每次重启服务器后都需要修改MYSQL的最大链接数
方法二：
1、修改mysql配置文件my.cnf：vim /etc/my.cnf
[mysqld]
port = 3306
socket = /var/lib/mysql/mysql.sock
skip-external-locking
key_buffer_size = 160M
max_allowed_packet = 100M
table_open_cache = 256
sort_buffer_size = 512K
net_buffer_length = 8K
read_buffer_size = 256K
read_rnd_buffer_size = 512K
myisam_sort_buffer_size = 80M
skip-grant-tables
lower_case_table_names=1
max_connections=10000
# Don't listen on a TCP/IP port at all. This can be a security enhancement,
# if all processes that need to connect to mysqld run on the same host.
找到：max_connections=151，修改为：max_connections=10000 （如没有就在[mysqld]下自行添加）