_threading_local.py 文件源码

def __del__(self):
        import threading

        key = object.__getattribute__(self, '_local__key')

        try:
            # We use the non-locking API since we might already hold the lock
            # (__del__ can be called at any point by the cyclic GC).
            threads = threading._enumerate()
        except:
            # If enumerating the current threads fails, as it seems to do
            # during shutdown, we'll skip cleanup under the assumption
            # that there is nothing to clean up.
            return

        for thread in threads:
            try:
                __dict__ = thread.__dict__
            except AttributeError:
                # Thread is dying, rest in peace.
                continue

            if key in __dict__:
                try:
                    del __dict__[key]
                except KeyError:
                    pass # didn't have anything in this thread