title: how are concurrent requests handled in PHP (using - threads, thread pool or child processes)
body: <p>I understand that PHP supports handling multiple concurrent connections and depending on server it can be configured as mentioned in this <a href="https://stackoverflow.com/a/1430890/2159867">answer</a></p>
  
  <p>How does server manages multiple connections does it forks a child process for each request or does it handle using threads or does it handles using a thread pool?</p>
  
  <p>The <a href="https://stackoverflow.com/a/1430890/2159867">linked answer</a> says a process is forked and then the author in comment says threads or process, which makes it confusing, if requests are served using child-processes, threads or thread pool?</p>