/etc/init.d/mysql does not respect resource limits when Linux starts up

[Jaime Sicam]

I'm filing this as a feature request

Current resource limits when Linux(CentOS 6) starts up:

/etc/security/limits.conf
root soft nproc 3000
root hard nproc unlimited

Limits of init process:
cat /proc/1/limits |grep processes
Max processes 3778 3778 processes

Limits of mysqld:
cat /proc/`pidof mysqld`/limits |grep processes
Max processes 3778 3778 processes

Resource limits of mysqld after restarting MySQL as root:
[root@localhost ~]# cat /proc/`pidof mysqld`/limits |grep processes
Max processes 3000 unlimited processes

Workaround is to use runuser to start mysqld_safe on /etc/init.d/mysql:
Look for:
      # Give extra arguments to mysqld with the my.cnf file. This script
      # may be overwritten at next upgrade.
      $bindir/mysqld_safe --datadir="$datadir" --pid-file="$mysqld_pid_file_path" $other_args >/dev/null 2>&1 &
      wait_for_pid created "$!" "$mysqld_pid_file_path"; return_value=$?

Change to:
      # Give extra arguments to mysqld with the my.cnf file. This script
      # may be overwritten at next upgrade.
      runuser -l mysql -c "$bindir/mysqld_safe --datadir='$datadir' --pid-file='$mysqld_pid_file_path' $other_args >/dev/null 2>&1 &"
      wait_for_pid created "$!" "$mysqld_pid_file_path"; return_value=$?

Under /etc/security/limits.conf, add resource limits to mysql:

/etc/security/limits.conf
mysql soft nproc 3000
mysql hard nproc unlimited

[Nilnandan Joshi (nilnandan-joshi)]

Able to reproduce the same.

[root@centos65 ~]# ps -ef | grep mysql
root 2621 1 0 15:02 pts/1 00:00:00 /bin/sh /usr/bin/mysqld_safe --datadir=/var/lib/mysql --pid-file=/var/lib/mysql/centos65.pid
mysql 2785 2621 4 15:02 pts/1 00:00:00 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib64/mysql/plugin --user=mysql --log-error=/var/log/mysqld.log --pid-file=/var/lib/mysql/centos65.pid --socket=/var/lib/mysql/mysql.sock
root 2811 2562 0 15:02 pts/1 00:00:00 grep mysql
[root@centos65 ~]#
[root@centos65 ~]# cat /proc/2785/limits |grep processes
Max processes 7809 unlimited processes
[root@centos65 ~]#

[root@centos65 ~]# cat /etc/security/limits.d/90-nproc.conf | grep nproc
* soft nproc 1024
root soft nproc 3000
root hard nproc unlimited
[root@centos65 ~]#

From another session:

[root@centos65 ~]# service mysql restart
Shutting down MySQL (Percona Server)... SUCCESS!
Starting MySQL (Percona Server). SUCCESS!
[root@centos65 ~]#
[root@centos65 ~]# ps -ef | grep mysql
root 3147 1 0 15:07 pts/2 00:00:00 /bin/sh /usr/bin/mysqld_safe --datadir=/var/lib/mysql --pid-file=/var/lib/mysql/centos65.pid
mysql 3311 3147 3 15:07 pts/2 00:00:00 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib64/mysql/plugin --user=mysql --log-error=/var/log/mysqld.log --pid-file=/var/lib/mysql/centos65.pid --socket=/var/lib/mysql/mysql.sock
root 3337 3089 0 15:07 pts/2 00:00:00 grep mysql
[root@centos65 ~]#
[root@centos65 ~]#
[root@centos65 ~]# cat /proc/3311/limits |grep processes
Max processes 7809 unlimited processes
[root@centos65 ~]#
[root@centos65 ~]# cat /proc/3147/limits |grep processes
Max processes 3000 unlimited processes
[root@centos65 ~]#

After reboot the server,
[root@centos65 ~]# ps -ef | grep mysql
root 1417 1 0 15:09 ? 00:00:00 /bin/sh /usr/bin/mysqld_safe --datadir=/var/lib/mysql --pid-file=/var/lib/mysql/centos65.pid
mysql 1581 1417 0 15:09 ? 00:00:00 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib64/mysql/plugin --user=mysql --log-error=/var/log/mysqld.log --pid-file=/var/lib/mysql/centos65.pid --socket=/var/lib/mysql/mysql.sock
root 1903 1885 0 15:11 pts/0 00:00:00 grep mysql
[root@centos65 ~]#
[root@centos65 ~]# cat /proc/1581/limits |grep processes
Max processes 7809 7809 processes
[root@centos65 ~]#
[root@centos65 ~]# cat /proc/1417/limits |grep processes
Max processes 7809 7809 processes
[root@centos65 ~]#

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PS-2452