This document describes the current stable version of Celery (3.1). For development docs, go here.
celery.result¶
celery.result¶
Task results/state and groups of results.
-
class
celery.result.
ResultBase
[source]¶ Base class for all results
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parent
= None¶ Parent result (if part of a chain)
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class
celery.result.
AsyncResult
(id, backend=None, task_name=None, app=None, parent=None)[source]¶ Query task state.
Parameters: -
exception
TimeoutError
¶ Error raised for timeouts.
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app
= None¶
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backend
= None¶ The task result backend to use.
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children
¶
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collect
(intermediate=False, **kwargs)[source]¶ Iterator, like
get()
will wait for the task to complete, but will also followAsyncResult
andResultSet
returned by the task, yielding(result, value)
tuples for each result in the tree.An example would be having the following tasks:
from celery import group from proj.celery import app @app.task(trail=True) def A(how_many): return group(B.s(i) for i in range(how_many))() @app.task(trail=True) def B(i): return pow2.delay(i) @app.task(trail=True) def pow2(i): return i ** 2
Note that the
trail
option must be enabled so that the list of children is stored inresult.children
. This is the default but enabled explicitly for illustration.Calling
collect()
would return:>>> from celery.result import ResultBase >>> from proj.tasks import A >>> result = A.delay(10) >>> [v for v in result.collect() ... if not isinstance(v, (ResultBase, tuple))] [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
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get
(timeout=None, propagate=True, interval=0.5, no_ack=True, follow_parents=True, EXCEPTION_STATES=frozenset(['FAILURE', 'RETRY', 'REVOKED']), PROPAGATE_STATES=frozenset(['FAILURE', 'REVOKED']))[source]¶ Wait until task is ready, and return its result.
Warning
Waiting for tasks within a task may lead to deadlocks. Please read Avoid launching synchronous subtasks.
Parameters: - timeout – How long to wait, in seconds, before the operation times out.
- propagate – Re-raise exception if the task failed.
- interval – Time to wait (in seconds) before retrying to retrieve the result. Note that this does not have any effect when using the amqp result store backend, as it does not use polling.
- no_ack – Enable amqp no ack (automatically acknowledge
message). If this is
False
then the message will not be acked. - follow_parents – Reraise any exception raised by parent task.
Raises: celery.exceptions.TimeoutError – if timeout is not
None
and the result does not arrive within timeout seconds.If the remote call raised an exception then that exception will be re-raised.
-
id
= None¶ The task’s UUID.
-
info
¶ When the task has been executed, this contains the return value. If the task raised an exception, this will be the exception instance.
-
ready
()[source]¶ Returns
True
if the task has been executed.If the task is still running, pending, or is waiting for retry then
False
is returned.
-
result
¶ When the task has been executed, this contains the return value. If the task raised an exception, this will be the exception instance.
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revoke
(connection=None, terminate=False, signal=None, wait=False, timeout=None)[source]¶ Send revoke signal to all workers.
Any worker receiving the task, or having reserved the task, must ignore it.
Parameters: - terminate – Also terminate the process currently working on the task (if any).
- signal – Name of signal to send to process if terminate. Default is TERM.
- wait – Wait for replies from workers. Will wait for 1 second
by default or you can specify a custom
timeout
. - timeout – Time in seconds to wait for replies if
wait
enabled.
-
serializable
()¶
-
state
¶ The tasks current state.
Possible values includes:
PENDING
The task is waiting for execution.STARTED
The task has been started.RETRY
The task is to be retried, possibly because of failure.FAILURE
The task raised an exception, or has exceeded the retry limit. Theresult
attribute then contains the exception raised by the task.SUCCESS
The task executed successfully. Theresult
attribute then contains the tasks return value.
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status
¶ The tasks current state.
Possible values includes:
PENDING
The task is waiting for execution.STARTED
The task has been started.RETRY
The task is to be retried, possibly because of failure.FAILURE
The task raised an exception, or has exceeded the retry limit. Theresult
attribute then contains the exception raised by the task.SUCCESS
The task executed successfully. Theresult
attribute then contains the tasks return value.
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supports_native_join
¶
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traceback
¶ Get the traceback of a failed task.
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wait
(timeout=None, propagate=True, interval=0.5, no_ack=True, follow_parents=True, EXCEPTION_STATES=frozenset(['FAILURE', 'RETRY', 'REVOKED']), PROPAGATE_STATES=frozenset(['FAILURE', 'REVOKED']))¶ Wait until task is ready, and return its result.
Warning
Waiting for tasks within a task may lead to deadlocks. Please read Avoid launching synchronous subtasks.
Parameters: - timeout – How long to wait, in seconds, before the operation times out.
- propagate – Re-raise exception if the task failed.
- interval – Time to wait (in seconds) before retrying to retrieve the result. Note that this does not have any effect when using the amqp result store backend, as it does not use polling.
- no_ack – Enable amqp no ack (automatically acknowledge
message). If this is
False
then the message will not be acked. - follow_parents – Reraise any exception raised by parent task.
Raises: celery.exceptions.TimeoutError – if timeout is not
None
and the result does not arrive within timeout seconds.If the remote call raised an exception then that exception will be re-raised.
-
exception
-
class
celery.result.
ResultSet
(results, app=None, **kwargs)[source]¶ Working with more than one result.
Parameters: results – List of result instances. -
add
(result)[source]¶ Add
AsyncResult
as a new member of the set.Does nothing if the result is already a member.
-
app
= None¶
-
backend
¶
-
discard
(result)[source]¶ Remove result from the set if it is a member.
If it is not a member, do nothing.
-
failed
()[source]¶ Did any of the tasks fail?
Returns: True
if one of the tasks failed. (i.e., raised an exception)
-
get
(timeout=None, propagate=True, interval=0.5, callback=None, no_ack=True)[source]¶ See
join()
This is here for API compatibility with
AsyncResult
, in addition it usesjoin_native()
if available for the current result backend.
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iter_native
(timeout=None, interval=0.5, no_ack=True)[source]¶ Backend optimized version of
iterate()
.New in version 2.2.
Note that this does not support collecting the results for different task types using different backends.
This is currently only supported by the amqp, Redis and cache result backends.
-
join
(timeout=None, propagate=True, interval=0.5, callback=None, no_ack=True)[source]¶ Gathers the results of all tasks as a list in order.
Note
This can be an expensive operation for result store backends that must resort to polling (e.g. database).
You should consider using
join_native()
if your backend supports it.Warning
Waiting for tasks within a task may lead to deadlocks. Please see Avoid launching synchronous subtasks.
Parameters: - timeout – The number of seconds to wait for results before the operation times out.
- propagate – If any of the tasks raises an exception, the exception will be re-raised.
- interval – Time to wait (in seconds) before retrying to retrieve a result from the set. Note that this does not have any effect when using the amqp result store backend, as it does not use polling.
- callback – Optional callback to be called for every result
received. Must have signature
(task_id, value)
No results will be returned by this function if a callback is specified. The order of results is also arbitrary when a callback is used. To get access to the result object for a particular id you will have to generate an index first:index = {r.id: r for r in gres.results.values()}
Or you can create new result objects on the fly:result = app.AsyncResult(task_id)
(both will take advantage of the backend cache anyway). - no_ack – Automatic message acknowledgement (Note that if this
is set to
False
then the messages will not be acknowledged).
Raises: celery.exceptions.TimeoutError – if
timeout
is notNone
and the operation takes longer thantimeout
seconds.
-
join_native
(timeout=None, propagate=True, interval=0.5, callback=None, no_ack=True)[source]¶ Backend optimized version of
join()
.New in version 2.2.
Note that this does not support collecting the results for different task types using different backends.
This is currently only supported by the amqp, Redis and cache result backends.
-
ready
()[source]¶ Did all of the tasks complete? (either by success of failure).
Returns: True
if all of the tasks has been executed.
-
remove
(result)[source]¶ Remove result from the set; it must be a member.
Raises: KeyError – if the result is not a member.
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results
= None¶ List of results in in the set.
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revoke
(connection=None, terminate=False, signal=None, wait=False, timeout=None)[source]¶ Send revoke signal to all workers for all tasks in the set.
Parameters: - terminate – Also terminate the process currently working on the task (if any).
- signal – Name of signal to send to process if terminate. Default is TERM.
- wait – Wait for replies from worker. Will wait for 1 second
by default or you can specify a custom
timeout
. - timeout – Time in seconds to wait for replies if
wait
enabled.
-
successful
()[source]¶ Was all of the tasks successful?
Returns: True
if all of the tasks finished successfully (i.e. did not raise an exception).
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supports_native_join
¶
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class
celery.result.
GroupResult
(id=None, results=None, **kwargs)[source]¶ Like
ResultSet
, but with an associated id.This type is returned by
group
, and the deprecated TaskSet, meth:~celery.task.TaskSet.apply_async method.It enables inspection of the tasks state and return values as a single entity.
Parameters: - id – The id of the group.
- results – List of result instances.
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children
¶
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id
= None¶ The UUID of the group.
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results
= None¶ List/iterator of results in the group
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save
(backend=None)[source]¶ Save group-result for later retrieval using
restore()
.Example:
>>> def save_and_restore(result): ... result.save() ... result = GroupResult.restore(result.id)
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serializable
()¶
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class
celery.result.
EagerResult
(id, ret_value, state, traceback=None)[source]¶ Result that we know has already been executed.
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result
¶ The tasks return value
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state
¶ The tasks state.
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status
¶ The tasks state.
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supports_native_join
¶
-
task_name
= None¶
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traceback
¶ The traceback if the task failed.
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wait
(timeout=None, propagate=True, **kwargs)¶
-