Function multi

python/python3/tornado/gen.py:438–486

Runs multiple asynchronous operations in parallel. ``children`` may either be a list or a dict whose values are yieldable objects. ``multi()`` returns a new yieldable object that resolves to a parallel structure containing their results. If ``children`` is a list, the result is a li

(
    children: Union[List[_Yieldable], Dict[Any, _Yieldable]],
    quiet_exceptions: "Union[Type[Exception], Tuple[Type[Exception], ...]]" = (),
)

def multi(
    children: Union[List[_Yieldable], Dict[Any, _Yieldable]],
    quiet_exceptions: "Union[Type[Exception], Tuple[Type[Exception], ...]]" = (),
) -> "Union[Future[List], Future[Dict]]":
    """Runs multiple asynchronous operations in parallel.

    ``children`` may either be a list or a dict whose values are
    yieldable objects. ``multi()`` returns a new yieldable
    object that resolves to a parallel structure containing their
    results. If ``children`` is a list, the result is a list of
    results in the same order; if it is a dict, the result is a dict
    with the same keys.

    That is, ``results = yield multi(list_of_futures)`` is equivalent
    to::

        results = []
        for future in list_of_futures:
            results.append(yield future)

    If any children raise exceptions, ``multi()`` will raise the first
    one. All others will be logged, unless they are of types
    contained in the ``quiet_exceptions`` argument.

    In a ``yield``-based coroutine, it is not normally necessary to
    call this function directly, since the coroutine runner will
    do it automatically when a list or dict is yielded. However,
    it is necessary in ``await``-based coroutines, or to pass
    the ``quiet_exceptions`` argument.

    This function is available under the names ``multi()`` and ``Multi()``
    for historical reasons.

    Cancelling a `.Future` returned by ``multi()`` does not cancel its
    children. `asyncio.gather` is similar to ``multi()``, but it does
    cancel its children.

    .. versionchanged:: 4.2
       If multiple yieldables fail, any exceptions after the first
       (which is raised) will be logged. Added the ``quiet_exceptions``
       argument to suppress this logging for selected exception types.

    .. versionchanged:: 4.3
       Replaced the class ``Multi`` and the function ``multi_future``
       with a unified function ``multi``. Added support for yieldables
       other than ``YieldPoint`` and `.Future`.

    """
    return multi_future(children, quiet_exceptions=quiet_exceptions)


Multi = multi