title: Python3 multiprocessing can only test a child process
body: <p>This is quite complex to explain, and a lot of code involve which I cannot paste here. </p>
  
  <p>But I have a Test application which executes Test cases through designated plugins.</p>
  
  <p>When the app is executed it creates a separate multi process called a writer, this module handles all updates to a web page which holds all running information about the test cases and their state. </p>
  
  <p>For this write I also create an interface (WrIf). This interface hold a Queue to the Writer Thread together with a weakref.proxy(). </p>
  
  <p>Now when the Test app starts executing its Test cases it creates new multiprocessor from where it can call the specific plugin. That means that the WrIf is "serialized" to this multi-process. </p>
  
  <p>For every call to the WrIf it makes a check to see if the main Writer thread is still running. however here is where I get a problem. I get the following assert when I try to call is_alive(). </p>
  
  <pre><code>assert self._parent_pid == os.getpid(), 'can only test a child process'
  AssertionError: can only test a child process
  </code></pre>
  
  <p>I can expand some on this however I think it will get muddy fast because the app is rather large and somewhat complex. </p>
  
  <p>Regards</p>