title: TypeError: init() missing 1 required positional argument: 'message' using Multiprocessing
body: <p>I am running a piece of code using a multiprocessing pool. The code works on a data set and fails on another one. Clearly the issue is data driven - Having said that I am not clear where to begin troubleshooting as the error I receive is the following. Any hints for a starting point would be most helpful.  Both sets of data are prepared using the same code - so I don't expect there to be a difference - yet here I am. </p>
  
  <p>Also see comment from Robert - we differ on os, and python version 3.6 (I have 3.4, he has 3.6) and quite different data sets. Yet error is identical down to the lines in the python code.</p>
  
  <p>My suspicions: </p>
  
  <ol>
  <li>there is a memory limit per core that is being enforced.</li>
  <li><p>there is some period of time after which the process literally collects - finds the process is not over and gives up.</p>
  
  <p>Exception in thread Thread-9:</p>
  
  <p>Traceback (most recent call last):</p>
  
  <p>File "C:\Program Files\Python\WinPython-64bit-3.4.4.4Qt5\python-3.4.4.amd64\lib\threading.py", line 911, in _bootstrap_inner
      self.run()</p>
  
  <p>File "C:\Program Files\Python\WinPython-64bit-3.4.4.4Qt5\python-3.4.4.amd64\lib\threading.py", line 859, in run
      self._target(*self._args, **self._kwargs)</p>
  
  <p>File "C:\Program Files\Python\WinPython-64bit-3.4.4.4Qt5\python-3.4.4.amd64\lib\multiprocessing\pool.py", line 429, in _handle_results
      task = get()</p>
  
  <p>File "C:\Program Files\Python\WinPython-64bit-3.4.4.4Qt5\python-3.4.4.amd64\lib\multiprocessing\connection.py", line 251, in recv
      return ForkingPickler.loads(buf.getbuffer())</p>
  
  <p>TypeError: <strong>init</strong>() missing 1 required positional argument: 'message'</p></li>
  </ol>