STINNER Victor <victor.stinner@haypocalc.com> added the comment:
In which case can it be None?
Oh, I misunderstood threading.py. current_thread().ident cannot be None. During the bootstrap of a thread, Thread._ident is None, but current_thread().ident is not None because current_thread() creates a dummy thread object having the right identifer. This dummy object is destroyed at soon as the Thread object is started (see Thread._bootstrap_inner). current_thread().ident is a little bit "suboptimal" because it gets the identifier of the thread, it reads the corresponding thread object, and then it gets the identifier of the thread object. def current_thread(): ... return _active[_get_ident()] ... ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue12028> _______________________________________