title: What is httpd <defunct>?
body: <pre><code>32537 apache    16   0 87424  15m 7324 S  2.3  0.3   0:00.52 httpd              
   3302 mysql     15   0  156m  41m 4756 S  1.3  0.7  10:50.91 mysqld             
    489 apache    16   0 87016  14m 6692 S  0.7  0.2   0:00.27 httpd              
    990 apache    15   0     0    0    0 Z  0.7  0.0   0:00.12 httpd &lt;defunct&gt;    
    665 apache    15   0 86992  13m 5644 S  0.3  0.2   0:00.20 httpd              
  32218 apache    15   0 87356  14m 6344 S  0.3  0.2   0:00.53 httpd              
      1 root      15   0  2160  640  556 S  0.0  0.0   0:01.18 init  
  </code></pre>
  
  <p>From <code>top</code>, there is an occasional <code>httpd &lt;defunct&gt;</code> showing up. What does it do? </p>
  
  <p>I found that the web server sometimes does not response to <code>FPDF</code> (print PDF at user's request). Is it related?</p>
  
  <p>UPDATE, with loading information:</p>
  
  <pre><code>top - 11:55:59 up 17:30,  6 users,  load average: 0.53, 0.47, 0.80
  Tasks: 322 total,   1 running, 320 sleeping,   0 stopped,   1 zombie
  Cpu(s):  0.7%us,  0.2%sy,  0.0%ni, 95.1%id,  3.9%wa,  0.0%hi,  0.1%si,  0.0%st
  Mem:   6219412k total,  5944068k used,   275344k free,    21024k buffers
  Swap:  5140792k total,       96k used,  5140696k free,  5270708k cached
  
    PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND           
   1951 apache    16   0     0    0    0 Z  0.9  0.0   0:00.33 httpd &lt;defunct&gt;    
   2267 apache    15   0 86992  13m 5876 S  0.9  0.2   0:00.22 httpd              
   3302 mysql     15   0  156m  41m 4756 S  0.9  0.7  11:43.72 mysqld             
   2220 apache    15   0 87204  14m 6496 S  0.6  0.2   0:00.28 httpd              
   2340 apache    15   0 87828  13m 5588 S  0.6  0.2   0:00.22 httpd              
   2341 apache    17   0 88236  14m 5564 S  0.6  0.2   0:00.15 httpd              
    842 apache    16   0 87432  15m 7180 S  0.3  0.2   0:00.81 httpd              
   2225 apache    18   0 88236  14m 5560 S  0.3  0.2   0:00.17 httpd              
   2401 apache    15   0 86916  12m 5344 S  0.3  0.2   0:00.11 httpd              
      1 root      24   0  2160  640  556 S  0.0  0.0   0:01.18 init               
  </code></pre>