Apache often restarts - I don't get the reason why

[ehrenwert]

Hello,

at the moment I can see that apache 2.4 on Debian 8 is restarting very often:

[Mon Dec 14 03:29:33.127396 2015] [mpm_event:notice] [pid 6764:tid 140215195498368] AH00491: caught SIGTERM, shutting down

[Mon Dec 14 09:20:26.061830 2015] [core:warn] [pid 6875:tid 140485499373440] AH00045: child process 6880 still did not exit, sending a SIGTERM

[Mon Dec 14 09:20:28.063987 2015] [core:warn] [pid 6875:tid 140485499373440] AH00045: child process 6880 still did not exit, sending a SIGTERM

[Mon Dec 14 09:20:30.066147 2015] [core:warn] [pid 6875:tid 140485499373440] AH00045: child process 6880 still did not exit, sending a SIGTERM

[Mon Dec 14 09:20:32.068302 2015] [mpm_event:notice] [pid 6875:tid 140485499373440] AH00491: caught SIGTERM, shutting down

[Mon Dec 14 09:23:45.545226 2015] [mpm_event:notice] [pid 30996:tid 140226066446208] AH00491: caught SIGTERM, shutting down

[Mon Dec 14 09:27:30.070837 2015] [mpm_event:notice] [pid 31846:tid 139815613970304] AH00491: caught SIGTERM, shutting down

[Mon Dec 14 11:32:02.398875 2015] [mpm_event:notice] [pid 596:tid 140021672986496] AH00491: caught SIGTERM, shutting down

[Mon Dec 14 11:41:00.243856 2015] [mpm_event:notice] [pid 13562:tid 139908709832576] AH00491: caught SIGTERM, shutting down

[Mon Dec 14 11:42:44.043026 2015] [mpm_event:notice] [pid 15588:tid 139746382944128] AH00491: caught SIGTERM, shutting down

[Mon Dec 14 12:28:38.919252 2015] [mpm_event:notice] [pid 16650:tid 139788384630656] AH00491: caught SIGTERM, shutting down

[Mon Dec 14 13:57:13.567318 2015] [core:warn] [pid 22971:tid 139937949468544] AH00045: child process 22976 still did not exit, sending a SIGTERM

[Mon Dec 14 13:57:15.568615 2015] [core:warn] [pid 22971:tid 139937949468544] AH00045: child process 22976 still did not exit, sending a SIGTERM

[Mon Dec 14 13:57:17.570682 2015] [core:warn] [pid 22971:tid 139937949468544] AH00045: child process 22976 still did not exit, sending a SIGTERM

[Mon Dec 14 13:57:20.573860 2015] [mpm_event:notice] [pid 22971:tid 139937949468544] AH00491: caught SIGTERM, shutting down

[Mon Dec 14 13:59:52.079996 2015] [mpm_event:notice] [pid 385:tid 140281824356224] AH00491: caught SIGTERM, shutting down

[Mon Dec 14 14:47:53.053938 2015] [core:warn] [pid 1682:tid 139817762129792] AH00045: child process 1687 still did not exit, sending a SIGTERM

[Mon Dec 14 14:47:55.056017 2015] [core:warn] [pid 1682:tid 139817762129792] AH00045: child process 1687 still did not exit, sending a SIGTERM

[Mon Dec 14 14:47:57.058107 2015] [core:warn] [pid 1682:tid 139817762129792] AH00045: child process 1687 still did not exit, sending a SIGTERM

[Mon Dec 14 14:48:00.171824 2015] [mpm_event:notice] [pid 1682:tid 139817762129792] AH00491: caught SIGTERM, shutting down

[Mon Dec 14 14:58:05.452318 2015] [mpm_event:notice] [pid 7861:tid 140133996627840] AH00491: caught SIGTERM, shutting down

This is my apache-configuration for limits

<IfModule worker.c>

        KeepAlive               On

        MaxKeepAliveRequests    10

        KeepAliveTimeout        2



        StartServers            10

        MinSpareThreads         25

        MaxSpareThreads         75



        ThreadLimit             64

        ThreadsPerChild         25



        MaxClients              1500

        MaxRequestsPerChild     100

</IfModule>



<IfModule prefork.c>

        KeepAlive               On

        MaxKeepAliveRequests    10

        KeepAliveTimeout        2



        StartServers            10

        MinSpareServers         25

        MaxSpareServers         75

        ServerLimit             1550

        MaxClients              1550

        MaxRequestsPerChild     4000

</IfModule>



<IfModule mpm_prefork_module>

        KeepAlive               On

        MaxKeepAliveRequests    10

        KeepAliveTimeout        2



        StartServers            10

        MinSpareServers         25

        MaxSpareServers         75

        ServerLimit             1550

        MaxClients              1500

        MaxRequestsPerChild     4000

</IfModule>

Any idea why apache is receiving SIGTERM that often?

 

[IgorG]

What is your Plesk version? Is it Plesk installed on VPS or standalone server? Are you sure that your server is not under DDOS attack?

 

[ehrenwert]

Hi IgorG,

It's PLESK 12.5 on a powerful LXC. The box gets 3-4 Bruteforce-Attempts per second from different Russian IPs (always 2-3 attempts to login per IP) but they are refused by ModSecurity.

 

[IgorG]

on a powerful LXC

Are you sure that there are enough resources?

 

[ehrenwert]

Yes, there is a lot of memory. The VPS uses 10% at the moment.