debug message as follows:
[DEBUG/MainProcess] created semlock with handle 140059486064640
[DEBUG/MainProcess] created semlock with handle 140059486060544
[DEBUG/MainProcess] created semlock with handle 140059486056448
[DEBUG/MainProcess] Queue._after_fork()
[DEBUG/MainProcess] created semlock with handle 140059486052352
[DEBUG/MainProcess] created semlock with handle 140059486048256
[DEBUG/MainProcess] created semlock with handle 140059486044160
[DEBUG/MainProcess] Queue._after_fork()
[DEBUG/MainProcess] Queue._start_thread()
[DEBUG/MainProcess] doing self._thread.start()
[DEBUG/MainProcess] starting thread to feed data to pipe
[DEBUG/MainProcess] ... done self._thread.start()
^CTraceback (most recent call last):
  File "main_simple.py", line 76, in <module>
    proc.join()
  File "/usr/lib/python3.6/multiprocessing/process.py", line 124, in join
    res = self._popen.wait(timeout)
  File "/usr/lib/python3.6/multiprocessing/popen_fork.py", line 50, in wait
    return self.poll(os.WNOHANG if timeout == 0.0 else 0)
  File "/usr/lib/python3.6/multiprocessing/popen_fork.py", line 28, in poll
    pid, sts = os.waitpid(self.pid, flag)
KeyboardInterrupt
^CException ignored in: <module 'threading' from '/usr/lib/python3.6/threading.py'>
Traceback (most recent call last):
  File "/usr/lib/python3.6/threading.py", line 1294, in _shutdown
    t.join()
  File "/usr/lib/python3.6/threading.py", line 1056, in join
    self._wait_for_tstate_lock()
  File "/usr/lib/python3.6/threading.py", line 1072, in _wait_for_tstate_lock
    elif lock.acquire(block, timeout):
KeyboardInterrupt
[INFO/MainProcess] process shutting down
[DEBUG/MainProcess] running all "atexit" finalizers with priority >= 0
[DEBUG/MainProcess] telling queue thread to quit
[INFO/MainProcess] calling join() for process Process-3
^CError in atexit._run_exitfuncs:
Traceback (most recent call last):
  File "/usr/lib/python3.6/multiprocessing/popen_fork.py", line 28, in poll
    pid, sts = os.waitpid(self.pid, flag)