title: 500 internal server error when execute a simple PHP loop program?
body: <pre><code>&lt;?php
  set_time_limit(600);
  while (1){
  usleep(30000000);
  }
  ?&gt;
  </code></pre>
  
  <p>The php program above causing the 500 internal server error. The problem is , I have set the time limit as 600 -> 10 minutes. And I am expecting it will run for ten minutes, for 30 second each , it will run a while loop for 1 time, and keep the activity to 10 minute. However, it return 500 internal server error  at round 2 minutes. What is the root cause / how to fix the problem ? thanks</p>