title: Why does my code return a broken pipe error when passing a manager.dict object as an argument?
body: <p>When running the following function:</p>
  <pre><code>#returns list of hostIds on network;
  def getHostsOnNetwork(surveyResults, hosts):
      notifEnabledMacs = [host['macAddr']
          for host in hosts.values()
          if host['notificationEnabled']
     ]
      macsOnNetwork = [host['mac'] for host in surveyResults]
  
      return [host['id']
          for host in hosts.values()
          if host['macAddr'] in macsOnNetwork
      ]
  </code></pre>
  <p>I pass a <code>manager.dict</code> object as 'hosts'. I receive the following error as a result:</p>
  <pre><code> Traceback (most recent call last):
     File &quot;/usr/lib/python3.8/multiprocessing/process.py&quot;, line 315, in _bootstrap
       self.run()
     File &quot;/usr/lib/python3.8/multiprocessing/process.py&quot;, line 108, in run
       self._target(*self._args, **self._kwargs)
     File &quot;main.py&quot;, line 101, in notifsProducer
       oldHostSet = currentHostSet
     File &quot;/home/patrick/notificationApp;/networking.py&quot;, line 82, in getHostsOnNetwork
       for host in hosts.values()
     File &quot;&lt;string&gt;&quot;, line 2, in values
     File &quot;/usr/lib/python3.8/multiprocessing/managers.py&quot;, line 834, in _callmethod
       conn.send((self._id, methodname, args, kwds))
     File &quot;/usr/lib/python3.8/multiprocessing/connection.py&quot;, line 206, in send
       self._send_bytes(_ForkingPickler.dumps(obj))
     File &quot;/usr/lib/python3.8/multiprocessing/connection.py&quot;, line 411, in _send_bytes
       self._send(header + buf)
     File &quot;/usr/lib/python3.8/multiprocessing/connection.py&quot;, line 368, in _send
       n = write(self._handle, buf)
   BrokenPipeError: [Errno 32] Broken pipe
  </code></pre>
  <p>It seems that the compiler is trying to make a write to the manager.dict object, but why? I don't alter any of its values in the function. How can I resolve this error?</p>
  <p>Any guidance is appreciated. Thanks.</p>