title: PHP Threads and Synchronization
body: <p>I'm new to PHP, so to get started I've decided to implement a singleton.</p>
  
  <p>While I am able to recreate the singleton pattern in php, but I am not sure how to implement double-checked locking.</p>
  
  <p>Is that even possible/needed in PHP.  I have read somewhere that PHP is not multithreaded?  Can someone confirm that?</p>
  
  <p>If it is multithreaded, can someone explain to me how lock() or synchronize() work in PHP?</p>
  
  <p>Thanks,
  Henry</p>