Multiple MySQL running but PID file could not be found

[root@tao Desktop]# service mysql start
Starting MySQL SUCCESS! 
[root@tao Desktop]# service mysql status
ERROR! Multiple MySQL running but PID file could not be found (4458 4245)

[root@tao Desktop]# kill 4458
[root@tao Desktop]# kill 4245
service mysql restart

ERROR! MySQL server PID file could not be found!

[root@tao Desktop]# service mysql status
 SUCCESS! MySQL running (4629)
[root@tao Desktop]# mysql
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)
[root@tao Desktop]# mysql -u root
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)
[root@tao Desktop]# mysql -u root -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.7.3-m13 MySQL Community Server (GPL)

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Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show databases;
+--------------------------+
| Database                 |
+--------------------------+
| information_schema       |
| cems                     |
| hive                     |
| mysql                    |
| performance_schema       |
| test                     |
| #mysql50#untitled folder |
+--------------------------+
7 rows in set (0.08 sec)