Percona Server removes its pid and socket

Faced with the fact that Percona Server on Centos 6 when re-start init script removes its pid and starts the second process. Checked at 51 and 55. A similar case is not found.

[root@localhost ~]# ps auxw | grep mysql
root 9826 0.0 0.0 103244 856 pts/1 S+ 15:35 0:00 grep mysql
[root@localhost ~]# ls -l /var/lib/mysql/
total 28692
-rw-rw----. 1 mysql mysql 18874368 Apr 20 14:32 ibdata1
-rw-rw----. 1 mysql mysql 5242880 Apr 20 15:15 ib_logfile0
-rw-rw----. 1 mysql mysql 5242880 Apr 20 14:12 ib_logfile1
drwx------. 2 mysql mysql 4096 Apr 20 14:08 mysql
drwx------. 2 mysql mysql 4096 Apr 20 14:08 performance_schema
-rw-r--r--. 1 mysql mysql 117 Apr 20 14:08 RPM_UPGRADE_HISTORY
-rw-r--r--. 1 mysql mysql 117 Apr 20 14:08 RPM_UPGRADE_MARKER-LAST
drwx------. 2 mysql mysql 4096 Apr 20 14:08 test
[root@localhost ~]# /etc/init.d/mysql start
Starting MySQL (Percona Server). SUCCESS!
[root@localhost ~]# ls -l /var/lib/mysql/
total 28696
-rw-rw----. 1 mysql mysql 18874368 Apr 20 15:35 ibdata1
-rw-rw----. 1 mysql mysql 5242880 Apr 20 15:35 ib_logfile0
-rw-rw----. 1 mysql mysql 5242880 Apr 20 14:12 ib_logfile1
-rw-rw----. 1 mysql mysql 5 Apr 20 15:35 localhost.localdomain.pid
drwx------. 2 mysql mysql 4096 Apr 20 14:08 mysql
srwxrwxrwx. 1 mysql mysql 0 Apr 20 15:35 mysql.sock
drwx------. 2 mysql mysql 4096 Apr 20 14:08 performance_schema
-rw-r--r--. 1 mysql mysql 117 Apr 20 14:08 RPM_UPGRADE_HISTORY
-rw-r--r--. 1 mysql mysql 117 Apr 20 14:08 RPM_UPGRADE_MARKER-LAST
drwx------. 2 mysql mysql 4096 Apr 20 14:08 test
[root@localhost ~]# /etc/init.d/mysql start
Starting MySQL (Percona Server) SUCCESS!
//When recalling the init-script erased pid and socket
[root@localhost ~]# ls -l /var/lib/mysql/
total 28692
-rw-rw----. 1 mysql mysql 18874368 Apr 20 15:35 ibdata1
-rw-rw----. 1 mysql mysql 5242880 Apr 20 15:35 ib_logfile0
-rw-rw----. 1 mysql mysql 5242880 Apr 20 14:12 ib_logfile1
drwx------. 2 mysql mysql 4096 Apr 20 14:08 mysql
drwx------. 2 mysql mysql 4096 Apr 20 14:08 performance_schema
-rw-r--r--. 1 mysql mysql 117 Apr 20 14:08 RPM_UPGRADE_HISTORY
-rw-r--r--. 1 mysql mysql 117 Apr 20 14:08 RPM_UPGRADE_MARKER-LAST
drwx------. 2 mysql mysql 4096 Apr 20 14:08 test
//two process at one time
[root@localhost ~]# ps auxw | grep mysql
root 9843 0.0 0.1 106064 1484 pts/1 S 15:35 0:00 /bin/sh /usr/bin/mysqld_safe --datadir=/var/lib/mysql --pid-file=/var/lib/mysql/localhost.localdomain.pid
mysql 9932 0.0 4.0 597860 41592 pts/1 Sl 15:35 0:00 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --user=mysql --log-error=/var/log/mysqld.log --pid-file=/var/lib/mysql/localhost.localdomain.pid --socket=/var/lib/mysql/mysql.sock
root 9969 0.0 0.1 106064 1484 pts/1 S 15:35 0:00 /bin/sh /usr/bin/mysqld_safe --datadir=/var/lib/mysql --pid-file=/var/lib/mysql/localhost.localdomain.pid
mysql 10060 0.1 2.9 389884 30456 pts/1 Sl 15:35 0:00 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --user=mysql --log-error=/var/log/mysqld.log --pid-file=/var/lib/mysql/localhost.localdomain.pid --socket=/var/lib/mysql/mysql.sock
root 10074 0.0 0.0 103244 856 pts/1 S+ 15:35 0:00 grep mysql
[root@localhost ~]#

Hi,
Can you share you my.cnf file so we can try to reproduce your error? I am not able to reproduce this on CentOS 6 with Percona Server 5.5 and 5.6.