каждые 4 минуты перезагружается MariaDB на сервере centos — помогите найти причину

Apache 2.4.6-90.el7.centos
MySQL 5.5.64-1.el7
PHP 5.4.16-46.1.el7_7
Perl 5.16.3-294.el7_6
Kernel 3.10.0-1062.9.1.el7.x86_64

лог Марии:

201031 10:16:10 Percona XtraDB (www.percona.com) 5.5.61-MariaDB-38.13 started; log sequence number 1966363809

201031 10:16:10 [Note] Plugin 'FEEDBACK' is disabled.

201031 10:16:10 [Note] Server socket created on IP: '127.0.0.1'.

201031 10:16:10 [Note] Event Scheduler: Loaded 0 events

201031 10:16:10 [Note] /usr/libexec/mysqld: ready for connections.

Version: '5.5.64-MariaDB' socket: '/var/lib/mysql/mysql.sock' port: 3306 MariaDB Server

201031 10:20:02 [Note] /usr/libexec/mysqld: Normal shutdown

201031 10:20:02 [Note] Event Scheduler: Purging the queue. 0 events

201031 10:20:02 InnoDB: Starting shutdown...

201031 10:20:04 InnoDB: Shutdown completed; log sequence number 1966363819

201031 10:20:04 [Note] /usr/libexec/mysqld: Shutdown complete

201031 10:20:04 mysqld_safe mysqld from pid file /var/run/mariadb/mariadb.pid ended

201031 10:20:05 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql

201031 10:20:05 [Note] /usr/libexec/mysqld (mysqld 5.5.64-MariaDB) starting as process 14360 ...

201031 10:20:05 InnoDB: The InnoDB memory heap is disabled

201031 10:20:05 InnoDB: Mutexes and rw_locks use GCC atomic builtins

201031 10:20:05 InnoDB: Compressed tables use zlib 1.2.7

201031 10:20:05 InnoDB: Using Linux native AIO

201031 10:20:05 InnoDB: Initializing buffer pool, size = 8.0G

201031 10:20:05 InnoDB: Completed initialization of buffer pool

201031 10:20:05 InnoDB: highest supported file format is Barracuda.

201031 10:20:05 InnoDB: Waiting for the background threads to start

201031 10:20:06 Percona XtraDB (www.percona.com) 5.5.61-MariaDB-38.13 started; log sequence number 1966363819

201031 10:20:06 [Note] Plugin 'FEEDBACK' is disabled.

201031 10:20:06 [Note] Server socket created on IP: '127.0.0.1'.

201031 10:20:06 [Note] Event Scheduler: Loaded 0 events

201031 10:20:06 [Note] /usr/libexec/mysqld: ready for connections.

Version: '5.5.64-MariaDB' socket: '/var/lib/mysql/mysql.sock' port: 3306 MariaDB Server

201031 10:24:01 [Note] /usr/libexec/mysqld: Normal shutdown

201031 10:24:01 [Note] Event Scheduler: Purging the queue. 0 events

201031 10:24:01 InnoDB: Starting shutdown...

201031 10:24:06 InnoDB: Shutdown completed; log sequence number 1966363829

201031 10:24:06 [Note] /usr/libexec/mysqld: Shutdown complete

201031 10:24:06 mysqld_safe mysqld from pid file /var/run/mariadb/mariadb.pid ended

201031 10:24:06 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql

201031 10:24:06 [Note] /usr/libexec/mysqld (mysqld 5.5.64-MariaDB) starting as process 15334 ...

201031 10:24:06 InnoDB: The InnoDB memory heap is disabled

201031 10:24:06 InnoDB: Mutexes and rw_locks use GCC atomic builtins

201031 10:24:06 InnoDB: Compressed tables use zlib 1.2.7

201031 10:24:06 InnoDB: Using Linux native AIO

201031 10:24:06 InnoDB: Initializing buffer pool, size = 8.0G

201031 10:24:07 InnoDB: Completed initialization of buffer pool

201031 10:24:07 InnoDB: highest supported file format is Barracuda.

201031 10:24:07 InnoDB: Waiting for the background threads to start

201031 10:24:08 Percona XtraDB (www.percona.com) 5.5.61-MariaDB-38.13 started; log sequence number 1966363829

201031 10:24:08 [Note] Plugin 'FEEDBACK' is disabled.

201031 10:24:08 [Note] Server socket created on IP: '127.0.0.1'.

201031 10:24:08 [Note] Event Scheduler: Loaded 0 events

201031 10:24:08 [Note] /usr/libexec/mysqld: ready for connections.