[Thu Dec 08 19:30:26.954314 2016] [mpm_prefork:error] [pid 379] (11)Resource temporarily unavailable: AH00159: fork: Unable to fork new process
[Thu Dec 08 19:30:36.957269 2016] [mpm_prefork:error] [pid 379] (11)Resource temporarily unavailable: AH00159: fork: Unable to fork new process
[Thu Dec 08 19:30:46.963876 2016] [mpm_prefork:error] [pid 379] (11)Resource temporarily unavailable: AH00159: fork: Unable to fork new process
[Thu Dec 08 19:30:56.967167 2016] [mpm_prefork:error] [pid 379] (11)Resource temporarily unavailable: AH00159: fork: Unable to fork new process
[Thu Dec 08 19:31:06.974127 2016] [mpm_prefork:error] [pid 379] (11)Resource temporarily unavailable: AH00159: fork: Unable to fork new process

Apache Server Status for example.com (via x.x.x.x)

Server Version: Apache/2.4.23 (Fedora) OpenSSL/1.0.2j-fips PHP/5.6.28
Server MPM: prefork
Server Built: Jul 18 2016 15:38:14
Current Time: Thursday, 08-Dec-2016 19:38:57 UTC
Restart Time: Thursday, 08-Dec-2016 19:29:02 UTC
Parent Server Config. Generation: 1
Parent Server MPM Generation: 0
Server uptime: 9 minutes 55 seconds
Server load: 2.86 2.38 1.48
Total accesses: 13045 - Total Traffic: 112.5 MB
CPU Usage: u485.32 s25.57 cu.05 cs.03 - 85.9% CPU load
21.9 requests/sec - 193.6 kB/second - 8.8 kB/request
165 requests currently being processed, 0 idle workers
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# ulimit -a
core file size          (blocks, -c) unlimited
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e) 0
file size               (blocks, -f) unlimited
pending signals                 (-i) 1546671
max locked memory       (kbytes, -l) 64
max memory size         (kbytes, -m) unlimited
open files                      (-n) 102400
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
real-time priority              (-r) 0
stack size              (kbytes, -s) 10240
cpu time               (seconds, -t) unlimited
max user processes              (-u) 1546671
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited

*            soft    core            unlimited
*            soft    nofile          102400
*            hard    nofile          152400
*            soft    sigpending      1546671
*            hard    sigpending      2046671
*            soft    stack           10240
*            hard    stack           14240
*            soft    nproc           1546671
*            hard    nproc           2046671

ServerLimit       8192
StartServers        40
MinSpareServers     25
MaxSpareServers    100
MaxClients        8192
MaxRequestsPerChild 10000

EnableMMAP Off