AH00161: server reached MaxRequestWorkers setting, consider raising the MaxRequestWorkers setting
<p>I've got a quite busy server: PHP (Wordpress) using W3TotalCache APC, Varnish for Apache and Cloudflare to handle all traffic.
Ubuntu 14.04.4 LTS</p>

<p>Only one website with an average about 60k hits/day.</p>

<p>I get this message every now and then, few times a day. Has nothing to do with temporarily traffic spikes, we compared times with Google Analytics.</p>

<pre><code>Thu Apr 28 14:14:42.938075 2016] [mpm_prefork:error] [pid 19137] AH00161: server reached MaxRequestWorkers setting, consider raising the MaxRequestWorkers setting
[Thu Apr 28 15:43:25.594147 2016] [core:notice] [pid 19137] AH00051: child pid 19866 exit signal Segmentation fault (11), possible coredump in /etc/apache2
[Thu Apr 28 15:43:25.594313 2016] [core:notice] [pid 19137] AH00051: child pid 20386 exit signal Segmentation fault (11), possible coredump in /etc/apache2
[Thu Apr 28 15:43:25.594407 2016] [core:notice] [pid 19137] AH00051: child pid 19143 exit signal Segmentation fault (11), possible coredump in /etc/apache2
[Thu Apr 28 15:43:25.594498 2016] [core:notice] [pid 19137] AH00051: child pid 19144 exit signal Segmentation fault (11), possible coredump in /etc/apache2
[Thu Apr 28 15:43:25.594572 2016] [core:notice] [pid 19137] AH00051: child pid 20597 exit signal Segmentation fault (11), possible coredump in /etc/apache2
[Thu Apr 28 15:43:25.594642 2016] [core:notice] [pid 19137] AH00051: child pid 20395 exit signal Segmentation fault (11), possible coredump in /etc/apache2
[Thu Apr 28 15:43:25.594704 2016] [core:notice] [pid 19137] AH00051: child pid 20424 exit signal Segmentation fault (11), possible coredump in /etc/apache2
[Thu Apr 28 15:43:25.594785 2016] [core:notice] [pid 19137] AH00051: child pid 20598 exit signal Segmentation fault (11), possible coredump in /etc/apache2
[Thu Apr 28 15:43:25.594870 2016] [core:notice] [pid 19137] AH00051: child pid 19861 exit signal Segmentation fault (11), possible coredump in /etc/apache2
[Thu Apr 28 15:43:25.594957 2016] [core:notice] [pid 19137] AH00051: child pid 19782 exit signal Segmentation fault (11), possible coredump in /etc/apache2
....
....
</code></pre>

<p>So I've increased MaxRequestWorkers first to 100, then 500, now its at 1024. But still happening.</p>

<p>This is my apache2.conf at the moment.
Code:</p>

<pre><code>&lt;IfModule mpm_worker_module&gt;
StartServers 256
MinSpareThreads 256
MaxSpareThreads 256
MaxClients 256
ServerLimit 256
ThreadLimit 256
ThreadsPerChild 256
MaxRequestWorkers 1024
MaxConnectionsPerChild 0
MaxRequestPerChild 1000
&lt;/IfModule&gt;
</code></pre>

<p>There is a lot of free RAM, and load average is around 0.5, sometimes over 1. But never seen it higher then 2. So server seems healthy to handle the traffic.</p>

<pre><code>top - 16:07:47 up 3 days, 18:18,  2 users,  load average: 0.57, 0.46, 0.55
Tasks: 113 total,   1 running, 112 sleeping,   0 stopped,   0 zombie
%Cpu(s): 10.5 us,  2.0 sy,  0.0 ni, 87.4 id,  0.1 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem:   8176816 total,  2372560 used,  5804256 free,   189684 buffers
KiB Swap:        0 total,        0 used,        0 free.  1286692 cached Mem

  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND                                                                                                                                              
21930 www-data  20   0  337212  83308  60072 S  24.9  1.0   0:52.89 apache2                                                                                                                                              
21945 www-data  20   0  327640  72684  58816 S  24.3  0.9   0:48.37 apache2                                                                                                                                              
 1182 nobody    20   0  702868 442268  83496 S   0.7  5.4  42:41.32 varnishd
</code></pre>

<p>Any ideas why Apache interrupts?</p>

<p>//j</p>