title: How PHP core is handling client connections?
body: <p>As far as I know, for each client connected to the server, PHP generates a new thread for it. 
  But I wonder whether it's true or not, and If it's true, how long does this thread stay alive?
  Does this thread maintain all the static variables properly? (like a DB connection)</p>
  
  <p>When this thread is destroyed, does it call all the destructors? </p>