group

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.

Attributes

Attribute	Type	Description
tasks	List[[Signature](signature.md?sid=celery_canvas_signature)]	Tasks in group.

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Constructor

Signature

def group(
    *tasks: List[[Signature](signature.md?sid=celery_canvas_signature)],
    **options: Any
) - > null

Parameters

Name	Type	Description
*tasks	List[[Signature](signature.md?sid=celery_canvas_signature)]	A list of signatures to be executed. If a single iterable is provided, it is used as the task list.
**options	Any	Execution options applied to all tasks within the group.

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Methods

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from_dict()

@classmethod
def from_dict(
    d: dict,
    app: [Celery](../app/base/celery.md?sid=celery_app_base_celery) = None
) - > [group](group.md?sid=celery_canvas_group)

Create a group signature from a dictionary that represents a group.

Parameters

Name	Type	Description
d	dict	The dictionary containing the group definition, including tasks in d['kwargs']['tasks']
app	[Celery](../app/base/celery.md?sid=celery_app_base_celery) = None	The Celery application instance to associate with the new group

Returns

Type	Description
[group](group.md?sid=celery_canvas_group)	A new group signature instance populated with the tasks and options from the dictionary

---

skew()

@classmethod
def skew(
    start: float = 1.0,
    stop: float = None,
    step: float = 1.0
) - > [group](group.md?sid=celery_canvas_group)

Staggers the execution of tasks in the group by applying incremental countdown delays.

Parameters

Name	Type	Description
start	float = 1.0	The initial countdown delay for the first task in the group
stop	float = None	The maximum countdown delay allowed
step	float = 1.0	The increment added to the countdown for each subsequent task

Returns

Type	Description
[group](group.md?sid=celery_canvas_group)	The group instance with updated countdown options for its member tasks

---

apply_async()

@classmethod
def apply_async(
    args: tuple = None,
    kwargs: dict = None,
    add_to_parent: bool = True,
    producer: Producer = None,
    link: [Signature](signature.md?sid=celery_canvas_signature) = None,
    link_error: [Signature](signature.md?sid=celery_canvas_signature) = None
) - > [GroupResult](../result/groupresult.md?sid=celery_result_groupresult)

Dispatches the group of tasks for asynchronous execution by the worker pool.

Parameters

Name	Type	Description
args	tuple = None	Positional arguments to pass to each task in the group
kwargs	dict = None	Keyword arguments to pass to each task in the group
add_to_parent	bool = True	Whether to attach the group result to the current task's trail for tracking
producer	Producer = None	The custom producer to use for publishing task messages
link	[Signature](signature.md?sid=celery_canvas_signature) = None	Unsupported for groups; raises TypeError if provided
link_error	[Signature](signature.md?sid=celery_canvas_signature) = None	Unsupported for groups; raises TypeError if provided

Returns

Type	Description
[GroupResult](../result/groupresult.md?sid=celery_result_groupresult)	A GroupResult instance containing the individual AsyncResult objects for each task

---

apply()

@classmethod
def apply(
    args: tuple = None,
    kwargs: dict = None
) - > [GroupResult](../result/groupresult.md?sid=celery_result_groupresult)

Executes the group of tasks locally and synchronously in the current process.

Parameters

Name	Type	Description
args	tuple = None	Positional arguments for the tasks
kwargs	dict = None	Keyword arguments for the tasks

Returns

Type	Description
[GroupResult](../result/groupresult.md?sid=celery_result_groupresult)	A GroupResult containing the results of the tasks executed eagerly

---

set_immutable()

@classmethod
def set_immutable(
    immutable: bool
) - > null

Sets the immutable flag on all tasks within the group to prevent argument merging.

Parameters

Name	Type	Description
immutable	bool	The boolean value to apply to each task's immutable property

Returns

Type	Description
null	null

---

stamp()

@classmethod
def stamp(
    visitor: [StampingVisitor](stampingvisitor.md?sid=celery_canvas_stampingvisitor) = None,
    append_stamps: bool = False,
    **headers: Any
) - > null

Applies custom headers or metadata tags to all tasks in the group using a visitor pattern.

Parameters

Name	Type	Description
visitor	[StampingVisitor](stampingvisitor.md?sid=celery_canvas_stampingvisitor) = None	An object that defines hooks for group start and end events
append_stamps	bool = False	Whether to append new stamps to existing ones instead of overwriting
**headers	Any	The metadata headers to be applied to the tasks

Returns

Type	Description
null	null

---

link()

@classmethod
def link(
    sig: [Signature](signature.md?sid=celery_canvas_signature)
) - > [Signature](signature.md?sid=celery_canvas_signature)

Links a callback signature to the first task in the group.

Parameters

Name	Type	Description
sig	[Signature](signature.md?sid=celery_canvas_signature)	The callback task to execute after the first task in the group finishes

Returns

Type	Description
[Signature](signature.md?sid=celery_canvas_signature)	The linked signature attached to the first task

---

link_error()

@classmethod
def link_error(
    sig: [Signature](signature.md?sid=celery_canvas_signature)
) - > tuple

Links an error callback signature to every task in the group.

Parameters

Name	Type	Description
sig	[Signature](signature.md?sid=celery_canvas_signature)	The error handler task to execute if any task in the group fails

Returns

Type	Description
tuple	A tuple of the linked error signatures applied to each child task

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freeze()

@classmethod
def freeze(
    group_id: str = None
) - > [GroupResult](../result/groupresult.md?sid=celery_result_groupresult)

Freezes the group, creating a GroupResult that represents the future results of the tasks.

Parameters

Name	Type	Description
group_id	str = None	The group ID to use; if None, a new UUID is generated

Returns

Type	Description
[GroupResult](../result/groupresult.md?sid=celery_result_groupresult)	A result object containing the frozen state and IDs of all tasks in the group

---

app()

@classmethod
def app() - > [Celery](../app/base/celery.md?sid=celery_app_base_celery)

Retrieves the Celery application instance associated with this group or its tasks.

Returns

Type	Description
[Celery](../app/base/celery.md?sid=celery_app_base_celery)	The resolved Celery application instance

---