Maximum number of client connections allowed.
When this setting is increased, then the file descriptor limits in the operating system might also have to be increased. Note that the number of file descriptors potentially used is more than maxClientConn. If each user connects under its own user name to the server, the theoretical maximum used is: maxClientConn + (max pool_size * total databases * total users)
If a database user is specified in the connection string (all users connect under the same user name), the theoretical maximum is: maxClientConn + (max pool_size * total databases)
The theoretical maximum should never be reached, unless somebody deliberately crafts a special load for it. Still, it means you should set the number of file descriptors to a safely high number.