mysql - 优化(max_connection, thread_cache_size 等的设置)

参考: https://serverfault.com/questions/408845/what-value-of-thread-cache-size-should-i-use

今天我们的服务器的自我检测程序停掉了. 

原因很有意思,mysql 的最大连接数超过了上线, 报错.

结局办法: (修改配置文件之后记得重启) 

修改 mysql的配置 (/etc/mysql/my.cnf ) 设置

[mysqld]
max_connections  = 2000

或者更高. 

另外, thread_cache_size 也需要设置, 设置办法: 

1. 查看3个参数;    

mysql> show global status like 'Connections'
    -> ;
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| Connections   | 368   |
+---------------+-------+

mysql> show global status like 'Threads_created';
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| Threads_created | 181   |
+-----------------+-------+

mysql> show global status like 'Max_used_connections';
+----------------------+-------+
| Variable_name        | Value |
+----------------------+-------+
| Max_used_connections | 152   |
+----------------------+-------+

然后,     Threads_created / Connections  如果 > 0.01 那么 就需要增加 thread_cache_size 

thread_cache_size 必须要高于   Max_used_connections .