1""" 2Expose a race in the _warnings module, which is the C backend for the 3warnings module. The "_warnings" module tries to access attributes of the 4"warnings" module (because of the API it has to support), but doing so 5during interpreter shutdown is problematic. Specifically, the call to 6PyImport_GetModuleDict() in Python/_warnings.c:get_warnings_attr will 7abort() if the modules dict has already been cleaned up. 8 9This crasher is timing-dependent, and more threads (NUM_THREADS) may be 10necessary to expose it reliably on different systems. 11""" 12 13import threading 14import warnings 15 16NUM_THREADS = 10 17 18class WarnOnDel(object): 19 def __del__(self): 20 warnings.warn("oh no something went wrong", UserWarning) 21 22def do_work(): 23 while True: 24 w = WarnOnDel() 25 26for i in range(NUM_THREADS): 27 t = threading.Thread(target=do_work) 28 t.setDaemon(1) 29 t.start() 30