How to limit the number of tftpd processes

Issue

• The per_source parameter of xinet.d has not effect on the number of tftpd processes:

$ grep per_source /etc/xinetd.d/tftp
        per_source              = 1
$ ps -edf | grep tftp
root     19323 19319  1 13:01 ?        00:00:00 /usr/sbin/in.tftpd -s /var/lib/tftpboot
nobody   19324 19323  8 13:01 ?        00:00:00 /usr/sbin/in.tftpd -s /var/lib/tftpboot
nobody   19325 19323  8 13:01 ?        00:00:00 /usr/sbin/in.tftpd -s /var/lib/tftpboot
nobody   19326 19323 12 13:01 ?        00:00:00 /usr/sbin/in.tftpd -s /var/lib/tftpboot
nobody   19327 19323 12 13:01 ?        00:00:00 /usr/sbin/in.tftpd -s /var/lib/tftpboot
...