B.4.2.6 Too many connections
If clients encounter
Too many connections errors when attempting to connect to the mysqld server, all available connections are in use by other clients.
The permitted number of connections is controlled by the
max_connections system variable. The default value is 151 to improve performance when MySQL is used with the Apache Web server. To support more connections, set
max_connections to a larger value.
mysqld actually permits
max_connections + 1 client connections. The extra connection is reserved for use by accounts that have the
SUPER privilege. By granting the privilege to administrators and not to normal users (who should not need it), an administrator who also has the
PROCESS privilege can connect to the server and use
SHOW PROCESSLIST to diagnose problems even if the maximum number of unprivileged clients are connected. See Section 220.127.116.11, “SHOW PROCESSLIST Statement”.
For more information about how the server handles client connections, see Section 18.104.22.168, “Connection Interfaces”.