Class group

celery/canvas.py:1478–1946

Creates a group of tasks to be executed in parallel. A group is lazy so you must call it to take action and evaluate the group. Note: If only one argument is passed, and that argument is an iterable then that'll be used as the list of tasks instead: this allows

@Signature.register_type()
class group(Signature):
    """Creates a group of tasks to be executed in parallel.

    A group is lazy so you must call it to take action and evaluate
    the group.

    Note:
        If only one argument is passed, and that argument is an iterable
        then that'll be used as the list of tasks instead: this
        allows us to use ``group`` with generator expressions.

    Example:
        >>> lazy_group = group([add.s(2, 2), add.s(4, 4)])
        >>> promise = lazy_group()  # <-- evaluate: returns lazy result.
        >>> promise.get()  # <-- will wait for the task to return
        [4, 8]

    Arguments:
        *tasks (List[Signature]): A list of signatures that this group will
            call. If there&#x27;s only one argument, and that argument is an
            iterable, then that&#x27;ll define the list of signatures instead.
        **options (Any): Execution options applied to all tasks
            in the group.

    Returns:
        ~celery.group: signature that when called will then call all of the
            tasks in the group (and return a :class:`GroupResult` instance
            that can be used to inspect the state of the group).
    """

    tasks = getitem_property('kwargs.tasks', 'Tasks in group.')

    @classmethod
    def from_dict(cls, d, app=None):
        """Create a group signature from a dictionary that represents a group.

        Example:
            >>> group_dict = {
                "task": "celery.group",
                "args": [],
                "kwargs": {
                    "tasks": [
                        {
                            "task": "add",
                            "args": [
                                1,
                                2
                            ],
                            "kwargs": {},
                            "options": {},
                            "subtask_type": None,
                            "immutable": False
                        },
                        {
                            "task": "add",
                            "args": [
                                3,
                                4