title: platform independent inter thread communication
body: <p>I have a process which receives multiple jobs and picks a thread from thread pool and assigns a job to it, this thread in turn may spawn another set of threads from its own thread pool. Now when a STOP request for a job comes to the main process, it should be forwarded to corresponding thread for that request and all the threads associated with that  job should clean themselves up and exit, My question is how to notify the worker threads about "STOP". </p>
  
  <p>A global variable can be used and worker threads can poll it frequently but there are lot of functions that a worker can be doing, and adding checks everywhere could work.</p>
  
  <p>Is there a clean approach? some kind of messaging layer. btw the code is <strong>C++</strong></p>