title: does boost::thread::timed_join(0) acquire a lock?
body: <p>I need to check if my boost::thread I've created is running from another thread. <a href="https://stackoverflow.com/questions/1667420/how-can-i-tell-reliably-if-a-boost-thread-has-exited-its-run-method">This</a> SO post explains you can do this by calling:</p>
  
  <pre><code>boost::posix_time::seconds waitTime(0);
  myBoostThread.timed_join(waitTime);
  </code></pre>
  
  <p>I can't have any critical sections in my client thread. Can I guarantee that <code>timed_join()</code> with 0 time argument be lock free?</p>