title: AH00161: server reached MaxRequestWorkers setting, consider raising the MaxRequestWorkers setting
body: <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>