首先我上次centos7.x 源码安装mysql未调优，同事在使用过程中报MySQL 1040 错误 Too many connections提示意思是说连接过多,通常有两种原因
两种方法
第一种：命令行修改
优点：即时生效
缺点：重启后失效
>mysql -uuser -ppassword(命令行登录MySQL)
mysql>show variables like 'max_connections';(查可以看当前的最大连接数)
msyql>set global max_connections=1000;(设置最大连接数为1000，可以再次查看是否设置成功)
mysql>exit(推出)我当前的最大连接数为151；
修改后为1000；
第二种：配置文件修改
优点：重启后依然生效
缺点：需要重启
我原来的my.cnf配置文件，请大家看好版本
[root@server-mysql ~]# cat /etc/my.cnf
# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/5.7/en/server-configuration-defaults.html
# *** DO NOT EDIT THIS FILE. It's a template which will be copied to the
# *** default location during install, and will be replaced if you
# *** upgrade to a newer version of MySQL.
[mysqld]
# Remove leading # and set to the amount of RAM for the most important data
# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.
# innodb_buffer_pool_size = 128M
# Remove leading # to turn on a very important data integrity option: logging
# changes to the binary log between backups.
# log_bin
# These are commonly set, remove the # and set as required.
# basedir = .....
# datadir = .....
# port = .....
# server_id = .....
# socket = .....
# Remove leading # to set options mainly useful for reporting servers.
# The server defaults are faster for transactions and fast SELECTs.
# Adjust sizes as needed, experiment to find the optimal values.
# join_buffer_size = 128M
# sort_buffer_size = 2M
# read_rnd_buffer_size = 2M
sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES
max_connections = 1000参考： https://dev.mysql.com/doc/refman/5.7/en/too-many-connections.html 官网手册
本文转自 yanconggod 51CTO博客，原文链接:
http://blog.51cto.com/yanconggod/2058551
