The following 'thread_repr.py' script:
--------------------------------------

import threading, atexit

def foo():
    print(threading.currentThread())

atexit.register(foo)



gives the following output:
---------------------------

Error in atexit._run_exitfuncs:
Traceback (most recent call last):
  File "thread_repr.py", line 4, in foo
    print(threading.currentThread())
  File "/usr/local/lib/python3.5/threading.py", line 826, in __repr__
    self.is_alive() # easy way to get ._is_stopped set when appropriate
  File "/usr/local/lib/python3.5/threading.py", line 1122, in is_alive
    self._wait_for_tstate_lock(False)
  File "/usr/local/lib/python3.5/threading.py", line 1078, in _wait_for_tstate_lock
    assert self._is_stopped
AssertionError