Function _make_invoke_excepthook

Lib/threading.py:1301–1349

()

def _make_invoke_excepthook():
    # Create a local namespace to ensure that variables remain alive
    # when _invoke_excepthook() is called, even if it is called late during
    # Python shutdown. It is mostly needed for daemon threads.

    old_excepthook = excepthook
    old_sys_excepthook = _sys.excepthook
    if old_excepthook is None:
        raise RuntimeError("threading.excepthook is None")
    if old_sys_excepthook is None:
        raise RuntimeError("sys.excepthook is None")

    sys_exc_info = _sys.exc_info
    local_print = print
    local_sys = _sys

    def invoke_excepthook(thread):
        global excepthook
        try:
            hook = excepthook
            if hook is None:
                hook = old_excepthook

            args = ExceptHookArgs([*sys_exc_info(), thread])

            hook(args)
        except Exception as exc:
            exc.__suppress_context__ = True
            del exc

            if local_sys is not None and local_sys.stderr is not None:
                stderr = local_sys.stderr
            else:
                stderr = thread._stderr

            local_print("Exception in threading.excepthook:",
                        file=stderr, flush=True)

            if local_sys is not None and local_sys.excepthook is not None:
                sys_excepthook = local_sys.excepthook
            else:
                sys_excepthook = old_sys_excepthook

            sys_excepthook(*sys_exc_info())
        finally:
            # Break reference cycle (exception stored in a variable)
            args = None

    return invoke_excepthook


# The timer class was contributed by Itamar Shtull-Trauring