Confirmed on Ubuntu:

openxs@ao756:~$ mysql -uroot -proot test
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 37
Server version: 5.5.37-35.0-657.saucy (Ubuntu)

Copyright (c) 2009-2014 Percona LLC and/or its affiliates
Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

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

mysql> show variables like '%handlers%';
mysql> show variables like '%handlers%';
+-------------------------------+-------+
| Variable_name                 | Value |
+-------------------------------+-------+
| handlersocket_accept_balance  | 0     |
| handlersocket_address         |       |
| handlersocket_backlog         | 32768 |
| handlersocket_epoll           | 1     |
| handlersocket_plain_secret    |       |
| handlersocket_plain_secret_wr |       |
| handlersocket_port            | 9998  |
| handlersocket_port_wr         |       |
| handlersocket_rcvbuf          | 0     |
| handlersocket_readsize        | 0     |
| handlersocket_sndbuf          | 0     |
| handlersocket_threads         | 16    |
| handlersocket_threads_wr      | 1     |
| handlersocket_timeout         | 300   |
| handlersocket_verbose         | 10    |
| handlersocket_wrlock_timeout  | 12    |
+-------------------------------+-------+
16 rows in set (0,01 sec)

mysql> show plugins;
+--------------------------------+----------+--------------------+------------------+---------+
| Name                           | Status   | Type               | Library          | License |
+--------------------------------+----------+--------------------+------------------+---------+
| binlog                         | ACTIVE   | STORAGE ENGINE     | NULL             | GPL     |
| mysql_native_password          | ACTIVE   | AUTHENTICATION     | NULL             | GPL     |
| mysql_old_password             | ACTIVE   | AUTHENTICATION     | NULL             | GPL     |
| MyISAM                         | ACTIVE   | STORAGE ENGINE     | NULL             | GPL     |
| MEMORY                         | ACTIVE   | STORAGE ENGINE     | NULL             | GPL     |
| CSV                            | ACTIVE   | STORAGE ENGINE     | NULL             | GPL     |
| MRG_MYISAM                     | ACTIVE   | STORAGE ENGINE     | NULL             | GPL     |
| ARCHIVE                        | ACTIVE   | STORAGE ENGINE     | NULL             | GPL     |
| PERFORMANCE_SCHEMA             | ACTIVE   | STORAGE ENGINE     | NULL             | GPL     |
| FEDERATED                      | DISABLED | STORAGE ENGINE     | NULL             | GPL     |
| InnoDB                         | ACTIVE   | STORAGE ENGINE     | NULL             | GPL     |
| INNODB_RSEG                    | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_UNDO_LOGS               | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_TRX                     | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_LOCKS                   | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_LOCK_WAITS              | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_CMP                     | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_CMP_RESET               | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_CMPMEM                  | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_CMPMEM_RESET            | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_SYS_TABLES              | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_SYS_TABLESTATS          | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_SYS_INDEXES             | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_SYS_COLUMNS             | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_SYS_FIELDS              | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_SYS_FOREIGN             | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_SYS_FOREIGN_COLS        | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_SYS_STATS               | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_TABLE_STATS             | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_INDEX_STATS             | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_BUFFER_POOL_PAGES       | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_BUFFER_POOL_PAGES_INDEX | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_BUFFER_POOL_PAGES_BLOB  | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| XTRADB_ADMIN_COMMAND           | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_CHANGED_PAGES           | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_BUFFER_PAGE             | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_BUFFER_PAGE_LRU         | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| INNODB_BUFFER_POOL_STATS       | ACTIVE   | INFORMATION SCHEMA | NULL             | GPL     |
| BLACKHOLE                      | ACTIVE   | STORAGE ENGINE     | NULL             | GPL     |
| partition                      | ACTIVE   | STORAGE ENGINE     | NULL             | GPL     |
| handlersocket                  | ACTIVE   | DAEMON             | handlersocket.so | BSD     |
+--------------------------------+----------+--------------------+------------------+---------+
41 rows in set (0,01 sec)

mysql> exit
Bye
openxs@ao756:~$ ps aux | grep mysqld
root     24591  0.0  0.0   4440   760 pts/1    S    13:18   0:00 /bin/sh /usr/bin/mysqld_safe
mysql    24683  0.4  1.1 1469000 44224 pts/1   Sl   13:18   0:00 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/lib/mysql/ao756.err --pid-file=/var/lib/mysql/ao756.pid
openxs   24889  0.0  0.0  15092   992 pts/1    S+   13:19   0:00 grep --color=auto mysqld
openxs@ao756:~$ sudo kill -15 `pidof mysqld`
openxs@ao756:~$ ps aux | grep mysqld
root     24591  0.0  0.0   4440   760 pts/1    S    13:18   0:00 /bin/sh /usr/bin/mysqld_safe
mysql    24683  0.3  1.1 1469000 44224 pts/1   Sl   13:18   0:00 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/lib/mysql/ao756.err --pid-file=/var/lib/mysql/ao756.pid
openxs   24897  0.0  0.0  15092   988 pts/1    S+   13:20   0:00 grep --color=auto mysqld
openxs@ao756:~$ sudo service mysql stop
 * Stopping MySQL (Percona Server) mysqld
... (it hangs) ...