Apache misbehavior?

Question

linux

Good afternoon! I have a server running ubuntu 16.04 with the following hardware configuration: Processor: AMD A8-6600K, RAM: 8GB, Disks: 2 WD Blue 1TB 7200 disks in RAID1. VestaCP is running on this server (without nginx, just an apache web server) with one site - a small cloud for employees on NextCloud, the load is not large (there are not many employees), but every 2-3 days the site crashes, namely, the apache process goes crazy :

Screenshot

After rebooting the server, the site works again for 2-3 days as a working clock, then the same story happens with Apache and the server reboots again. Stop apache process via vesta panel or no console exits. What can be wrong?

apache logs

[Thu May 23 09:50:07.434408 2019] [mpm_prefork:notice] [pid 3444] AH00171: Graceful restart requested, doing restart
AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using cloud.site.ru. Set the 'ServerName' directive globally to suppress this message
[Thu May 23 09:50:08.242406 2019] [:notice] [pid 3444] mod_ruid2/0.9.8 enabled
[Thu May 23 09:50:08.243330 2019] [mpm_prefork:notice] [pid 3444] AH00163: Apache/2.4.18 (Ubuntu) mod_fcgid/2.3.9 OpenSSL/1.0.2g configured -- resuming normal operations
[Thu May 23 09:50:08.243341 2019] [core:notice] [pid 3444] AH00094: Command line: '/usr/sbin/apache2'
[Thu May 23 09:55:07.104907 2019] [mpm_prefork:notice] [pid 3444] AH00171: Graceful restart requested, doing restart
AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using cloud.site.ru. Set the 'ServerName' directive globally to suppress this message
[Thu May 23 09:55:07.324023 2019] [:notice] [pid 3444] mod_ruid2/0.9.8 enabled
[Thu May 23 09:55:07.324931 2019] [mpm_prefork:notice] [pid 3444] AH00163: Apache/2.4.18 (Ubuntu) mod_fcgid/2.3.9 OpenSSL/1.0.2g configured -- resuming normal operations
[Thu May 23 09:55:07.324941 2019] [core:notice] [pid 3444] AH00094: Command line: '/usr/sbin/apache2'
[Thu May 23 10:00:08.050215 2019] [mpm_prefork:notice] [pid 3444] AH00171: Graceful restart requested, doing restart
AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using cloud.site.ru. Set the 'ServerName' directive globally to suppress this message
[Thu May 23 10:00:09.178528 2019] [:notice] [pid 3444] mod_ruid2/0.9.8 enabled
[Thu May 23 10:00:09.179435 2019] [mpm_prefork:notice] [pid 3444] AH00163: Apache/2.4.18 (Ubuntu) mod_fcgid/2.3.9 OpenSSL/1.0.2g configured -- resuming normal operations
[Thu May 23 10:00:09.179446 2019] [core:notice] [pid 3444] AH00094: Command line: '/usr/sbin/apache2'
[Thu May 23 10:05:08.994408 2019] [mpm_prefork:notice] [pid 3444] AH00171: Graceful restart requested, doing restart
AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using cloud.site.ru. Set the 'ServerName' directive globally to suppress this message
[Thu May 23 10:05:09.310217 2019] [:notice] [pid 3444] mod_ruid2/0.9.8 enabled
[Thu May 23 10:05:09.347034 2019] [mpm_prefork:notice] [pid 3444] AH00163: Apache/2.4.18 (Ubuntu) mod_fcgid/2.3.9 OpenSSL/1.0.2g configured -- resuming normal operations
[Thu May 23 10:05:09.347064 2019] [core:notice] [pid 3444] AH00094: Command line: '/usr/sbin/apache2'
[Thu May 23 10:10:07.147677 2019] [mpm_prefork:notice] [pid 3444] AH00171: Graceful restart requested, doing restart
AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using cloud.site.ru. Set the 'ServerName' directive globally to suppress this message
[Thu May 23 10:10:07.365417 2019] [:notice] [pid 3444] mod_ruid2/0.9.8 enabled
[Thu May 23 10:10:07.366469 2019] [mpm_prefork:notice] [pid 3444] AH00163: Apache/2.4.18 (Ubuntu) mod_fcgid/2.3.9 OpenSSL/1.0.2g configured -- resuming normal operations
[Thu May 23 10:10:07.366482 2019] [core:notice] [pid 3444] AH00094: Command line: '/usr/sbin/apache2'
[Thu May 23 10:15:07.093704 2019] [mpm_prefork:notice] [pid 3444] AH00171: Graceful restart requested, doing restart
AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using cloud.site.ru. Set the 'ServerName' directive globally to suppress this message
[Thu May 23 10:15:07.327831 2019] [:notice] [pid 3444] mod_ruid2/0.9.8 enabled
[Thu May 23 10:15:07.328741 2019] [mpm_prefork:notice] [pid 3444] AH00163: Apache/2.4.18 (Ubuntu) mod_fcgid/2.3.9 OpenSSL/1.0.2g configured -- resuming normal operations
[Thu May 23 10:15:07.328752 2019] [core:notice] [pid 3444] AH00094: Command line: '/usr/sbin/apache2'
[Thu May 23 10:21:10.739828 2019] [mpm_prefork:notice] [pid 3444] AH00169: caught SIGTERM, shutting down
[Thu May 23 10:21:49.539010 2019] [suexec:notice] [pid 1660] AH01232: suEXEC mechanism enabled (wrapper: /usr/lib/apache2/suexec)
[Thu May 23 10:21:51.718836 2019] [:notice] [pid 1674] mod_ruid2/0.9.8 enabled
[Thu May 23 10:21:51.724666 2019] [mpm_prefork:notice] [pid 1674] AH00163: Apache/2.4.18 (Ubuntu) mod_fcgid/2.3.9 OpenSSL/1.0.2g configured -- resuming normal operations
[Thu May 23 10:21:51.724706 2019] [core:notice] [pid 1674] AH00094: Command line: '/usr/sbin/apache2'
[Thu May 23 10:25:09.607778 2019] [mpm_prefork:notice] [pid 1674] AH00171: Graceful restart requested, doing restart
AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using cloud.site.ru. Set the 'ServerName' directive globally to suppress this message
[Thu May 23 10:25:09.874649 2019] [:notice] [pid 1674] mod_ruid2/0.9.8 enabled
[Thu May 23 10:25:09.875582 2019] [mpm_prefork:notice] [pid 1674] AH00163: Apache/2.4.18 (Ubuntu) mod_fcgid/2.3.9 OpenSSL/1.0.2g configured -- resuming normal operations
[Thu May 23 10:25:09.875594 2019] [core:notice] [pid 1674] AH00094: Command line: '/usr/sbin/apache2'
[Thu May 23 10:30:07.195116 2019] [mpm_prefork:notice] [pid 1674] AH00171: Graceful restart requested, doing restart
AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using cloud.site.ru. Set the 'ServerName' directive globally to suppress this message
[Thu May 23 10:30:07.418507 2019] [:notice] [pid 1674] mod_ruid2/0.9.8 enabled
[Thu May 23 10:30:07.419586 2019] [mpm_prefork:notice] [pid 1674] AH00163: Apache/2.4.18 (Ubuntu) mod_fcgid/2.3.9 OpenSSL/1.0.2g configured -- resuming normal operations
[Thu May 23 10:30:07.419600 2019] [core:notice] [pid 1674] AH00094: Command line: '/usr/sbin/apache2'
[Thu May 23 10:35:06.856901 2019] [mpm_prefork:notice] [pid 1674] AH00171: Graceful restart requested, doing restart
AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using cloud.site.ru. Set the 'ServerName' directive globally to suppress this message
[Thu May 23 10:35:07.083028 2019] [:notice] [pid 1674] mod_ruid2/0.9.8 enabled
[Thu May 23 10:35:07.084128 2019] [mpm_prefork:notice] [pid 1674] AH00163: Apache/2.4.18 (Ubuntu) mod_fcgid/2.3.9 OpenSSL/1.0.2g configured -- resuming normal operations
[Thu May 23 10:35:07.084143 2019] [core:notice] [pid 1674] AH00094: Command line: '/usr/sbin/apache2'
[Thu May 23 10:40:07.224752 2019] [mpm_prefork:notice] [pid 1674] AH00171: Graceful restart requested, doing restart
AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using cloud.site.ru. Set the 'ServerName' directive globally to suppress this message
[Thu May 23 10:40:07.456792 2019] [:notice] [pid 1674] mod_ruid2/0.9.8 enabled
[Thu May 23 10:40:07.457750 2019] [mpm_prefork:notice] [pid 1674] AH00163: Apache/2.4.18 (Ubuntu) mod_fcgid/2.3.9 OpenSSL/1.0.2g configured -- resuming normal operations
[Thu May 23 10:40:07.457760 2019] [core:notice] [pid 1674] AH00094: Command line: '/usr/sbin/apache2'