Comment 4 for bug 1673712

fwiw, mysqld honors the limits as indicated in /etc/security/limits.conf but ignores its own limits:

root@trusty:/root# service mysql restart
 * Stopping Percona Server 5.7.18-14
...
 * Percona Server 5.7.18-14 is stopped
 * Re-starting Percona Server 5.7.18-14
..
 * Percona Server 5.7.18-14 is started
root@trusty:/root#
root@trusty:/root# grep nofile /etc/security/limits.conf
# - nofile - max number of open files
root soft nofile 1048576
root hard nofile 1048576
mysql soft nofile 1048576
mysql hard nofile 1048576
root@trusty:/root#
root@trusty:/root# mysql -uroot -p -e "show global variables like '%open_files%'";
Enter password:
+-------------------+---------+
| Variable_name | Value |
+-------------------+---------+
| innodb_open_files | 2000 |
| open_files_limit | 1048576 | <---
+-------------------+---------+
root@trusty:/root# grep -B1 open /etc/my.cnf
[mysqld]
open-files-limit=1024000
--
[mysqld_safe]
open-files-limit=1024000
root@trusty:/root#