Mysql 參數配置

1. back_log

# back_log is the number of connections the operating system can keep in
# the listen queue, before the MySQL connection manager thread has
# processed them. If you have a very high connection rate and experience
# "connection refused" errors, you might need to increase this value.
# Check your OS documentation for the maximum value of this parameter.
# Attempting to set back_log higher than your operating system limit
# will have no effect.

該參數不能大於操作系統允許的值，可以在/proc/sys/net/ipv4/tcp_max_syn_backlog 中查看OS允許的最大值。