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1.0.3 [2010-05-15 03:00 P.M CEST]
Important notes
* Messages are now acked *just before* the task function is executed.
This is the behavior we've wanted all along, but couldn't have because of
limitations in the multiprocessing module.
The previous behavior was not good, and the situation worsened with the
release of 1.0.1, so this change will definitely improve
reliability, performance and operations in general.
For more information please see
* Database result backend: result now explicitly sets ``null=True`` as
``django-picklefield`` version 0.1.5 changed the default behavior
right under our noses :(
This means those who created their celery tables (via syncdb or
celeryinit) with picklefield versions >= 0.1.5 has to alter their tables to
allow the result field to be ``NULL`` manually.
ALTER TABLE celery_taskmeta MODIFY result TEXT NULL
* Removed ``Task.rate_limit_queue_type``, as it was not really useful
and made it harder to refactor some parts.
* Now depends on carrot >= 0.10.4
* Now depends on billiard >= 0.3.0
* AMQP backend: Added timeout support for ``result.get()`` /
* New task option: ``Task.acks_late`` (default: ``CELERY_ACKS_LATE``)
Late ack means the task messages will be acknowledged **after** the task
has been executed, not *just before*, which is the default behavior.
Note that this means the tasks may be executed twice if the worker
crashes in the middle of their execution. Not acceptable for most
applications, but desirable for others.
* Added crontab-like scheduling to periodic tasks.
Like a cron job, you can specify units of time of when
you would like the task to execute. While not a full implementation
of cron's features, it should provide a fair degree of common scheduling
You can specify a minute (0-59), an hour (0-23), and/or a day of the
week (0-6 where 0 is Sunday, or by names: sun, mon, tue, wed, thu, fri,
.. code-block:: python
from celery.task.schedules import crontab
from celery.decorators import periodic_task
@periodic_task(run_every=crontab(hour=7, minute=30))
def every_morning():
print("Runs every morning at 7:30a.m")
@periodic_task(run_every=crontab(hour=7, minute=30, day_of_week="mon"))
def every_monday_morning():
print("Run every monday morning at 7:30a.m")
def every_hour():
print("Runs every hour on the clock. e.g. 1:30, 2:30, 3:30 etc.")
Note that this a late addition. While we have unittests, due to the
nature of this feature we haven't been able to completely test this
in practice, so consider this experimental.
* ``TaskPool.apply_async``: Now supports the ``accept_callback`` argument.
* ``apply_async``: Now raises :exc:`ValueError` if task args is not a list,
or kwargs is not a tuple (
* ``Task.max_retries`` can now be ``None``, which means it will retry forever.
* Celerybeat: Now reuses the same connection when publishing large
sets of tasks.
* Modified the task locking example in the documentation to use
``cache.add`` for atomic locking.
* Added experimental support for a *started* status on tasks.
If ``Task.track_started`` is enabled the task will report its status
as "started" when the task is executed by a worker.
The default value is ``False`` as the normal behaviour is to not
report that level of granularity. Tasks are either pending, finished,
or waiting to be retried. Having a "started" status can be useful for
when there are long running tasks and there is a need to report which
task is currently running.
The global default can be overridden by the ``CELERY_TRACK_STARTED``
* User Guide: New section ``Tips and Best Practices``.
Contributions welcome!
Remote control commands
* Remote control commands can now send replies back to the caller.
Existing commands has been improved to send replies, and the client
interface in ``celery.task.control`` has new keyword arguments: ``reply``,
``timeout`` and ``limit``. Where reply means it will wait for replies,
timeout is the time in seconds to stop waiting for replies, and limit
is the maximum number of replies to get.
By default, it will wait for as many replies as possible for one second.
* rate_limit(task_name, destination=all, reply=False, timeout=1, limit=0)
Worker returns ``{"ok": message}`` on success,
or ``{"failure": message}`` on failure.
>>> from celery.task.control import rate_limit
>>> rate_limit("tasks.add", "10/s", reply=True)
[{'worker1': {'ok': 'new rate limit set successfully'}},
{'worker2': {'ok': 'new rate limit set successfully'}}]
* ping(destination=all, reply=False, timeout=1, limit=0)
Worker returns the simple message ``"pong"``.
>>> from celery.task.control import ping
>>> ping(reply=True)
[{'worker1': 'pong'},
{'worker2': 'pong'},
* revoke(destination=all, reply=False, timeout=1, limit=0)
Worker simply returns ``True``.
>>> from celery.task.control import revoke
>>> revoke("419e46eb-cf6a-4271-86a8-442b7124132c", reply=True)
[{'worker1': True},
{'worker2'; True}]
* You can now add your own remote control commands!
Remote control commands are functions registered in the command
registry. Registering a command is done using
.. code-block:: python
from celery.task.control import Panel
def reset_broker_connection(panel, **kwargs):
return {"ok": "connection re-established"}
With this module imported in the worker, you can launch the command
using ``celery.task.control.broadcast``::
>>> from celery.task.control import broadcast
>>> broadcast("reset_broker_connection", reply=True)
[{'worker1': {'ok': 'connection re-established'},
{'worker2': {'ok': 'connection re-established'}}]
**TIP** You can choose the worker(s) to receive the command
by using the ``destination`` argument::
>>> broadcast("reset_broker_connection", destination=["worker1"])
[{'worker1': {'ok': 'connection re-established'}]
* New remote control command: ``dump_reserved``
Dumps tasks reserved by the worker, waiting to be executed::
>>> from celery.task.control import broadcast
>>> broadcast("dump_reserved", reply=True)
[{'myworker1': [<TaskWrapper ....>]}]
* New remote control command: ``dump_schedule``
Dumps the workers currently registered ETA schedule.
These are tasks with an ``eta`` (or ``countdown``) argument
waiting to be executed by the worker.
>>> from celery.task.control import broadcast
>>> broadcast("dump_schedule", reply=True)
[{'w1': []},
{'w3': []},
{'w2': ['0. 2010-05-12 11:06:00 pri0 <TaskWrapper:
args:"(<Feeds freq_max:3600 freq_min:60
start:2184.0 stop:3276.0>,)",
kwargs:"{'page': 2}"}>']},
{'w4': ['0. 2010-05-12 11:00:00 pri0 <TaskWrapper:
args:"(<Feeds freq_max:3600 freq_min:60
start:1092.0 stop:2184.0>,)",
kwargs:"{\'page\': 1}"}>',
'1. 2010-05-12 11:12:00 pri0 <TaskWrapper:
args:"(<Feeds freq_max:3600 freq_min:60
start:3276.0 stop:4365>,)",
kwargs:"{\'page\': 3}"}>']}]
* Mediator thread no longer blocks for more than 1 second.
With rate limits enabled and when there was a lot of remaining time,
the mediator thread could block shutdown (and potentially block other
jobs from coming in).
* Remote rate limits was not properly applied
* Now handles exceptions with unicode messages correctly in
* Database backend: ``TaskMeta.result``: default value should be ``None``
not empty string.
1.0.2 [2010-03-31 12:50 P.M CET]
* Deprecated: ``CELERY_BACKEND``, please use ``CELERY_RESULT_BACKEND``
* We now use a custom logger in tasks. This logger supports task magic
keyword arguments in formats.
The default format for tasks (``CELERYD_TASK_LOG_FORMAT``) now includes
the id and the name of tasks so the origin of task log messages can
easily be traced.
Example output::
[2010-03-25 13:11:20,317: INFO/PoolWorker-1]
[tasks.add(a6e1c5ad-60d9-42a0-8b24-9e39363125a4)] Hello from add
To revert to the previous behavior you can set::
[%(asctime)s: %(levelname)s/%(processName)s] %(message)s
* Unittests: Don't disable the django test database teardown,
instead fixed the underlying issue which was caused by modifications
to the ``DATABASE_NAME`` setting (
* Django Loader: New config ``CELERY_DB_REUSE_MAX`` (max number of tasks
to reuse the same database connection)
The default is to use a new connection for every task.
We would very much like to reuse the connection, but a safe number of
reuses is not known, and we don't have any way to handle the errors
that might happen, which may even be database dependent.
* celeryd: The worker components are now configurable: ``CELERYD_POOL``,
The default configuration is as follows:
.. code-block:: python
CELERYD_POOL = "celery.worker.pool.TaskPool"
CELERYD_MEDIATOR = "celery.worker.controllers.Mediator"
CELERYD_ETA_SCHEDULER = "celery.worker.controllers.ScheduleController"
CELERYD_LISTENER = "celery.worker.listener.CarrotListener"
The ``CELERYD_POOL`` setting makes it easy to swap out the multiprocessing
pool with a threaded pool, or how about a twisted/eventlet pool?
Consider the competition for the first pool plug-in started!
* Debian init scripts: Use ``-a`` not ``&&``
* Debian init scripts: Now always preserves ``$CELERYD_OPTS`` from the
``/etc/default/celeryd`` and ``/etc/default/celerybeat``.
* celery.beat.Scheduler: Fixed a bug where the schedule was not properly
flushed to disk if the schedule had not been properly initialized.
* celerybeat: Now syncs the schedule to disk when receiving the ``SIGTERM``
and ``SIGINT`` signals.
* Control commands: Make sure keywords arguments are not in unicode.
* ETA scheduler: Was missing a logger object, so the scheduler crashed
when trying to log that a task had been revoked.
* management.commands.camqadm: Fixed typo ``camqpadm`` -> ``camqadm``
* PeriodicTask.delta_resolution: Was not working for days and hours, now fixed
by rounding to the nearest day/hour.
* Fixed a potential infinite loop in ``BaseAsyncResult.__eq__``, although
there is no evidence that it has ever been triggered.
* celeryd: Now handles messages with encoding problems by acking them and
emitting an error message.
1.0.1 [2010-02-24 07:05 P.M CET]
* Tasks are now acknowledged early instead of late.
This is done because messages can only be acked within the same
connection channel, so if the connection is lost we would have to refetch
the message again to acknowledge it.
This might or might not affect you, but mostly those running tasks with a
really long execution time are affected, as all tasks that has made it
all the way into the pool needs to be executed before the worker can
safely terminate (this is at most the number of pool workers, multiplied
We multiply the prefetch count by default to increase the performance at
times with bursts of tasks with a short execution time. If this doesn't
apply to your use case, you should be able to set the prefetch multiplier
to zero, without sacrificing performance.
Please note that a patch to :mod:`multiprocessing` is currently being
worked on, this patch would enable us to use a better solution, and is
scheduled for inclusion in the ``1.2.0`` release.
* celeryd now shutdowns cleanly when receving the ``TERM`` signal.
* celeryd now does a cold shutdown if the ``INT`` signal is received (Ctrl+C),
this means it tries to terminate as soon as possible.
* Caching of results now moved to the base backend classes, so no need
to implement this functionality in the base classes.
* Caches are now also limited in size, so their memory usage doesn't grow
out of control.
You can set the maximum number of results the cache
can hold using the ``CELERY_MAX_CACHED_RESULTS`` setting (the default
is five thousand results). In addition, you can refetch already retrieved
results using ``backend.reload_task_result`` +
``backend.reload_taskset_result`` (that's for those who want to send
results incrementally).
* ``celeryd`` now works on Windows again.
Note that if running with Django,
you can't use ``project.settings`` as the settings module name, but the
following should work::
$ python celeryd --settings=settings
* Execution: ``.messaging.TaskPublisher.send_task`` now
incorporates all the functionality apply_async previously did.
Like converting countdowns to eta, so :func:`celery.execute.apply_async` is
now simply a convenient front-end to
:meth:`celery.messaging.TaskPublisher.send_task`, using
the task classes default options.
Also :func:`celery.execute.send_task` has been
introduced, which can apply tasks using just the task name (useful
if the client does not have the destination task in its task registry).
>>> from celery.execute import send_task
>>> result = send_task("", args=[], kwargs={})
>>> result.get()
* ``camqadm``: This is a new utility for command line access to the AMQP API.
Excellent for deleting queues/bindings/exchanges, experimentation and
$ camqadm
1> help
Gives an interactive shell, type ``help`` for a list of commands.
When using Django, use the management command instead::
$ python camqadm
1> help
* Redis result backend: To conform to recent Redis API changes, the following
settings has been deprecated:
These will emit a ``DeprecationWarning`` if used.
A ``REDIS_PASSWORD`` setting has been added, so you can use the new
simple authentication mechanism in Redis.
* The redis result backend no longer calls ``SAVE`` when disconnecting,
as this is apparently better handled by Redis itself.
* If ``settings.DEBUG`` is on, celeryd now warns about the possible
memory leak it can result in.
* The ETA scheduler now sleeps at most two seconds between iterations.
* The ETA scheduler now deletes any revoked tasks it might encounter.
As revokes are not yet persistent, this is done to make sure the task
is revoked even though it's currently being hold because its eta is e.g.
a week into the future.
* The ``task_id`` argument is now respected even if the task is executed
eagerly (either using apply, or ``CELERY_ALWAYS_EAGER``).
* The internal queues are now cleared if the connection is reset.
* New magic keyword argument: ``delivery_info``.
Used by retry() to resend the task to its original destination using the same
* Events: Fields was not passed by ``.send()`` (fixes the uuid keyerrors
in celerymon)
* Added ``--schedule``/``-s`` option to celeryd, so it is possible to
specify a custom schedule filename when using an embedded celerybeat
server (the ``-B``/``--beat``) option.
* Better Python 2.4 compatibility. The test suite now passes.
* task decorators: Now preserve docstring as ``cls.__doc__``, (was previously
copied to ````)
* The ``testproj`` directory has been renamed to ``tests`` and we're now using
``nose`` + ``django-nose`` for test discovery, and ``unittest2`` for test
* New pip requirements files available in ``contrib/requirements``.
* TaskPublisher: Declarations are now done once (per process).
* Added ``Task.delivery_mode`` and the ``CELERY_DEFAULT_DELIVERY_MODE``
These can be used to mark messages non-persistent (i.e. so they are
lost if the broker is restarted).
* Now have our own ``ImproperlyConfigured`` exception, instead of using the
Django one.
* Improvements to the debian init scripts: Shows an error if the program is
not executeable. Does not modify ``CELERYD`` when using django with
1.0.0 [2010-02-10 04:00 P.M CET]
* Celery does not support detaching anymore, so you have to use the tools
available on your platform, or something like supervisord to make
celeryd/celerybeat/celerymon into background processes.
We've had too many problems with celeryd daemonizing itself, so it was
decided it has to be removed. Example startup scripts has been added to
* Debian, Ubuntu, (start-stop-daemon)
* Mac OS X launchd
* Supervisord (
In addition to ``--detach``, the following program arguments has been
removed: ``--uid``, ``--gid``, ``--workdir``, ``--chroot``, ``--pidfile``,
``--umask``. All good daemonization tools should support equivalent
functionality, so don't worry.
Also the following configuration keys has been removed:
* Default celeryd loglevel is now ``WARN``, to enable the previous log level
start celeryd with ``--loglevel=INFO``.
* Tasks are automatically registered.
This means you no longer have to register your tasks manually.
You don't have to change your old code right away, as it doesn't matter if
a task is registered twice.
If you don't want your task to be automatically registered you can set
the ``abstract`` attribute
.. code-block:: python
class MyTask(Task):
abstract = True
By using ``abstract`` only tasks subclassing this task will be automatically
registered (this works like the Django ORM).
If you don't want subclasses to be registered either, you can set the
``autoregister`` attribute to ``False``.
Incidentally, this change also fixes the problems with automatic name
assignment and relative imports. So you also don't have to specify a task name
anymore if you use relative imports.
* You can no longer use regular functions as tasks.
This change was added
because it makes the internals a lot more clean and simple. However, you can
now turn functions into tasks by using the ``@task`` decorator:
.. code-block:: python
from celery.decorators import task
def add(x, y):
return x + y
See the User Guide: :doc:`userguide/tasks` for more information.
* The periodic task system has been rewritten to a centralized solution.
This means ``celeryd`` no longer schedules periodic tasks by default,
but a new daemon has been introduced: ``celerybeat``.
To launch the periodic task scheduler you have to run celerybeat::
$ celerybeat
Make sure this is running on one server only, if you run it twice, all
periodic tasks will also be executed twice.
If you only have one worker server you can embed it into celeryd like this::
$ celeryd --beat # Embed celerybeat in celeryd.
* The supervisor has been removed.
This means the ``-S`` and ``--supervised`` options to ``celeryd`` is
no longer supported. Please use something like
* ``TaskSet.join`` has been removed, use ``TaskSetResult.join`` instead.
* The task status ``"DONE"`` has been renamed to `"SUCCESS"`.
* ``AsyncResult.is_done`` has been removed, use ``AsyncResult.successful``
* The worker no longer stores errors if ``Task.ignore_result`` is set, to
revert to the previous behaviour set
* The staticstics functionality has been removed in favor of events,
so the ``-S`` and ``--statistics`` switches has been removed.
* The module ``celery.task.strategy`` has been removed.
* ``celery.discovery`` has been removed, and it's ``autodiscover`` function is
now in ``celery.loaders.djangoapp``. Reason: Internal API.
* ``CELERY_LOADER`` now needs loader class name in addition to module name,
E.g. where you previously had: ``"celery.loaders.default"``, you now need
``"celery.loaders.default.Loader"``, using the previous syntax will result
in a DeprecationWarning.
* Detecting the loader is now lazy, and so is not done when importing
To make this happen ``celery.loaders.settings`` has
been renamed to ``load_settings`` and is now a function returning the
settings object. ``celery.loaders.current_loader`` is now also
a function, returning the current loader.
loader = current_loader
needs to be changed to::
loader = current_loader()
* The following configuration variables has been renamed and will be
deprecated in v1.2:
* The public api names in celery.conf has also changed to a consistent naming
* We now support consuming from an arbitrary number of queues.
To do this we had to rename the configuration syntax. If you use any of
the custom AMQP routing options (queue/exchange/routing_key, etc), you
should read the new FAQ entry:
The previous syntax is deprecated and scheduled for removal in v1.2.
* ```` has been renamed to ``TaskSet.apply_async``.
```` has now been deprecated, and is scheduled for
removal in v1.2.
* Rate limiting support (per task type, or globally).
* New periodic task system.
* Automatic registration.
* New cool task decorator syntax.
* celeryd now sends events if enabled with the ``-E`` argument.
Excellent for monitoring tools, one is already in the making
Current events include: worker-heartbeat,
worker-online, worker-offline.
* You can now delete (revoke) tasks that has already been applied.
* You can now set the hostname celeryd identifies as using the ``--hostname``
* Cache backend now respects ``CELERY_TASK_RESULT_EXPIRES``.
* Message format has been standardized and now uses ISO-8601 format
for dates instead of datetime.
* ``celeryd`` now responds to the ``HUP`` signal by restarting itself.
* Periodic tasks are now scheduled on the clock.
I.e. ``timedelta(hours=1)`` means every hour at :00 minutes, not every
hour from the server starts. To revert to the previous behaviour you
can set ``PeriodicTask.relative = True``.
* Now supports passing execute options to a TaskSets list of args, e.g.:
>>> ts = TaskSet(add, [([2, 2], {}, {"countdown": 1}),
... ([4, 4], {}, {"countdown": 2}),
... ([8, 8], {}, {"countdown": 3})])
* Got a 3x performance gain by setting the prefetch count to four times the
concurrency, (from an average task round-trip of 0.1s to 0.03s!).
A new setting has been added: ``CELERYD_PREFETCH_MULTIPLIER``, which
is set to ``4`` by default.
* Improved support for webhook tasks.
```` is now deprecated, replaced with the new and shiny
:mod:`celery.task.http`. With more reflective names, sensible interface,
and it's possible to override the methods used to perform HTTP requests.
* The results of tasksets are now cached by storing it in the result
* Now depends on carrot >= 0.8.1
* New dependencies: billiard, python-dateutil, django-picklefield
* No longer depends on python-daemon
* The ``uuid`` distribution is added as a dependency when running Python 2.4.
* Now remembers the previously detected loader by keeping it in
the ``CELERY_LOADER`` environment variable.
This may help on windows where fork emulation is used.
* ETA no longer sends datetime objects, but uses ISO 8601 date format in a
string for better compatibility with other platforms.
* No longer sends error mails for retried tasks.
* Task can now override the backend used to store results.
* Refactored the ExecuteWrapper, ``apply`` and ``CELERY_ALWAYS_EAGER`` now
also executes the task callbacks and signals.
* Now using a proper scheduler for the tasks with an ETA.
This means waiting eta tasks are sorted by time, so we don't have
to poll the whole list all the time.
* Now also imports modules listed in CELERY_IMPORTS when running
with django (as documented).
* Loglevel for stdout/stderr changed from INFO to ERROR
* ImportErrors are now properly propogated when autodiscovering tasks.
* You can now use ``celery.messaging.establish_connection`` to establish a
connection to the broker.
* When running as a separate service the periodic task scheduler does some
smart moves to not poll too regularly.
If you need faster poll times you can lower the value
* You can now change periodic task intervals at runtime, by making
``run_every`` a property, or subclassing ``PeriodicTask.is_due``.
* The worker now supports control commands enabled through the use of a
broadcast queue, you can remotely revoke tasks or set the rate limit for
a task type. See :mod:`celery.task.control`.
* The services now sets informative process names (as shown in ``ps``
listings) if the :mod:`setproctitle` module is installed.
* :exc:`celery.exceptions.NotRegistered` now inherits from :exc:`KeyError`,
and ``TaskRegistry.__getitem__``+``pop`` raises ``NotRegistered`` instead
* You can set the loader via the ``CELERY_LOADER`` environment variable.
* You can now set ``CELERY_IGNORE_RESULT`` to ignore task results by default
(if enabled, tasks doesn't save results or errors to the backend used).
* celeryd now correctly handles malformed messages by throwing away and
acknowledging the message, instead of crashing.
* Fixed a race condition that could happen while storing task results in the
* Reference now split into two sections; API reference and internal module
0.8.4 [2010-02-05 01:52 P.M CEST]
* Now emits a warning if the --detach argument is used.
--detach should not be used anymore, as it has several not easily fixed
bugs related to it. Instead, use something like start-stop-daemon,
supervisord or launchd (os x).
* Make sure logger class is process aware, even if running Python >= 2.6.
* Error e-mails are not sent anymore when the task is retried.
0.8.3 [2009-12-22 09:43 A.M CEST]
* Fixed a possible race condition that could happen when storing/querying
task results using the the database backend.
* Now has console script entry points in the file, so tools like
buildout will correctly install the programs celerybin and celeryinit.
0.8.2 [2009-11-20 03:40 P.M CEST]
* QOS Prefetch count was not applied properly, as it was set for every message
received (which apparently behaves like, "receive one more"), instead of only
set when our wanted value cahnged.
0.8.1 [2009-11-16 05:21 P.M CEST]
This release (with carrot 0.8.0) enables AMQP QoS (quality of service), which
means the workers will only receive as many messages as it can handle at a
time. As with any release, you should test this version upgrade on your
development servers before rolling it out to production!
* If you're using Python < 2.6 and you use the multiprocessing backport, then
multiprocessing version is required.
* All AMQP_* settings has been renamed to BROKER_*, and in addition
AMQP_SERVER has been renamed to BROKER_HOST, so before where you had::
AMQP_SERVER = "localhost"
AMQP_PORT = 5678
AMQP_USER = "myuser"
AMQP_PASSWORD = "mypassword"
AMQP_VHOST = "celery"
You need to change that to::
BROKER_HOST = "localhost"
BROKER_USER = "myuser"
BROKER_PASSWORD = "mypassword"
BROKER_VHOST = "celery"
* Custom carrot backends now need to include the backend class name, so before
where you had::
CARROT_BACKEND = "mycustom.backend.module"
you need to change it to::
CARROT_BACKEND = "mycustom.backend.module.Backend"
where ``Backend`` is the class name. This is probably ``"Backend"``, as
that was the previously implied name.
* New version requirement for carrot: 0.8.0
* Incorporated the multiprocessing backport patch that fixes the
``processName`` error.
* Ignore the result of PeriodicTask's by default.
* Added a Redis result store backend
* Allow /etc/default/celeryd to define additional options for the celeryd init
* MongoDB periodic tasks issue when using different time than UTC fixed.
* Windows specific: Negate test for available os.fork (thanks miracle2k)
* Now tried to handle broken PID files.
* Added a Django test runner to contrib that sets CELERY_ALWAYS_EAGER = True for testing with the database backend
* Added a CELERY_CACHE_BACKEND setting for using something other than the django-global cache backend.
* Use custom implementation of functools.partial (curry) for Python 2.4 support
(Probably still problems with running on 2.4, but it will eventually be
* Prepare exception to pickle when saving RETRY status for all backends.
* SQLite no concurrency limit should only be effective if the db backend is used.
0.8.0 [2009-09-22 03:06 P.M CEST]
* Add traceback to result value on failure.
**NOTE** If you use the database backend you have to re-create the
database table ``celery_taskmeta``.
Contact the mailinglist or IRC channel listed in README for help
doing this.
* Database tables are now only created if the database backend is used,
so if you change back to the database backend at some point,
be sure to initialize tables (django: ``syncdb``, python: ``celeryinit``).
(Note: This is only the case when using Django 1.1 or higher)
* Now depends on ``carrot`` version 0.6.0.
* Now depends on python-daemon 1.4.8
* Celery can now be used in pure Python (outside of a Django project).
This means celery is no longer Django specific.
For more information see the FAQ entry
`Can I use celery without Django?`_.
.. _`Can I use celery without Django?`:
* Celery now supports task retries.
See `Cookbook: Retrying Tasks`_ for more information.
.. _`Cookbook: Retrying Tasks`:
* We now have an AMQP result store backend.
It uses messages to publish task return value and status. And it's
incredibly fast!
See for more info!
* AMQP QoS (prefetch count) implemented:
This to not receive more messages than we can handle.
* Now redirects stdout/stderr to the celeryd logfile when detached
* Now uses ``inspect.getargspec`` to only pass default arguments
the task supports.
* Add Task.on_success, .on_retry, .on_failure handlers
See :meth:`celery.task.base.Task.on_success`,
* ``celery.utils.gen_unique_id``: Workaround for
* You can now customize what happens at worker start, at process init, etc
by creating your own loaders. (see :mod:`celery.loaders.default`,
:mod:`celery.loaders.djangoapp`, :mod:`celery.loaders`.)
* Support for multiple AMQP exchanges and queues.
This feature misses documentation and tests, so anyone interested
is encouraged to improve this situation.
* celeryd now survives a restart of the AMQP server!
Automatically re-establish AMQP broker connection if it's lost.
New settings:
Set to ``True`` to enable connection retries.
Maximum number of restarts before we give up. Default: ``100``.
* Fix an incompatibility between python-daemon and multiprocessing,
which resulted in the ``[Errno 10] No child processes`` problem when
* Fixed a possible DjangoUnicodeDecodeError being raised when saving pickled
data to Django's memcached cache backend.
* Better Windows compatibility.
* New version of the pickled field (taken from
* New signals introduced: ``task_sent``, ``task_prerun`` and
``task_postrun``, see :mod:`celery.signals` for more information.
* ``TaskSetResult.join`` caused ``TypeError`` when ``timeout=None``.
Thanks Jerzy Kozera. Closes #31
* ``views.apply`` should return ``HttpResponse`` instance.
Thanks to Jerzy Kozera. Closes #32
* ``PeriodicTask``: Save conversion of ``run_every`` from ``int``
to ``timedelta`` to the class attribute instead of on the instance.
* Exceptions has been moved to ``celery.exceptions``, but are still
available in the previous module.
* Try to rollback transaction and retry saving result if an error happens
while setting task status with the database backend.
* jail() refactored into :class:`celery.execute.ExecuteWrapper`.
* ``views.apply`` now correctly sets mimetype to "application/json"
* ``views.task_status`` now returns exception if status is RETRY
* ``views.task_status`` now returns traceback if status is "FAILURE"
or "RETRY"
* Documented default task arguments.
* Add a sensible __repr__ to ExceptionInfo for easier debugging
* Fix documentation typo ``.. import map`` -> ``.. import dmap``.
Thanks mikedizon
0.6.0 [2009-08-07 06:54 A.M CET]
* Fixed a bug where tasks raising unpickleable exceptions crashed pool
workers. So if you've had pool workers mysteriously dissapearing, or
problems with celeryd stopping working, this has been fixed in this
* Fixed a race condition with periodic tasks.
* The task pool is now supervised, so if a pool worker crashes,
goes away or stops responding, it is automatically replaced with
a new one.
* is now automatically generated out of class module+name, e.g.
``"djangotwitter.tasks.UpdateStatusesTask"``. Very convenient. No idea why
we didn't do this before. Some documentation is updated to not manually
specify a task name.
* Tested with Django 1.1
* New Tutorial: Creating a click counter using carrot and celery
* Database entries for periodic tasks are now created at ``celeryd``
startup instead of for each check (which has been a forgotten TODO/XXX
in the code for a long time)
* New settings variable: ``CELERY_TASK_RESULT_EXPIRES``
Time (in seconds, or a `datetime.timedelta` object) for when after
stored task results are deleted. For the moment this only works for the
database backend.
* ``celeryd`` now emits a debug log message for which periodic tasks
has been launched.
* The periodic task table is now locked for reading while getting
periodic task status. (MySQL only so far, seeking patches for other
* A lot more debugging information is now available by turning on the
``DEBUG`` loglevel (``--loglevel=DEBUG``).
* Functions/methods with a timeout argument now works correctly.
* New: ``celery.strategy.even_time_distribution``:
With an iterator yielding task args, kwargs tuples, evenly distribute
the processing of its tasks throughout the time window available.
* Log message ``Unknown task ignored...`` now has loglevel ``ERROR``
* Log message ``"Got task from broker"`` is now emitted for all tasks, even if
the task has an ETA (estimated time of arrival). Also the message now
includes the ETA for the task (if any).
* Acknowledgement now happens in the pool callback. Can't do ack in the job
target, as it's not pickleable (can't share AMQP connection, etc)).
* Added note about .delay hanging in README
* Tests now passing in Django 1.1
* Fixed discovery to make sure app is in INSTALLED_APPS
* Previously overrided pool behaviour (process reap, wait until pool worker
available, etc.) is now handled by ``multiprocessing.Pool`` itself.
* Convert statistics data to unicode for use as kwargs. Thanks Lucy!
0.4.1 [2009-07-02 01:42 P.M CET]
* Fixed a bug with parsing the message options (``mandatory``,
``routing_key``, ``priority``, ``immediate``)
0.4.0 [2009-07-01 07:29 P.M CET]
* Adds eager execution. ``celery.execute.apply``|``Task.apply`` executes the
function blocking until the task is done, for API compatiblity it
returns an ``celery.result.EagerResult`` instance. You can configure
celery to always run tasks locally by setting the
``CELERY_ALWAYS_EAGER`` setting to ``True``.
* Now depends on ``anyjson``.
* 99% coverage using python ``coverage`` 3.0.
0.3.20 [2009-06-25 08:42 P.M CET]
* New arguments to ``apply_async`` (the advanced version of
``delay_task``), ``countdown`` and ``eta``;
>>> # Run 10 seconds into the future.
>>> res = apply_async(MyTask, countdown=10);
>>> # Run 1 day from now
>>> res = apply_async(MyTask, +
... timedelta(days=1)
* Now unlinks the pidfile if it's stale.
* Lots of more tests.
* Now compatible with carrot >= 0.5.0.
* **IMPORTANT** The ``subtask_ids`` attribute on the ``TaskSetResult``
instance has been removed. To get this information instead use:
>>> subtask_ids = [subtask.task_id for subtask in ts_res.subtasks]
* ```` now respects extra message options from the task class.
* Task: Add attribute ``ignore_result``: Don't store the status and
return value. This means you can't use the
``celery.result.AsyncResult`` to check if the task is
done, or get its return value. Only use if you need the performance
and is able live without these features. Any exceptions raised will
store the return value/status as usual.
* Task: Add attribute ``disable_error_emails`` to disable sending error
emails for that task.
* Should now work on Windows (although running in the background won't
work, so using the ``--detach`` argument results in an exception
being raised.)
* Added support for statistics for profiling and monitoring.
To start sending statistics start ``celeryd`` with the
``--statistics`` option. Then after a while you can dump the results
by running ``python celerystats``. See
``celery.monitoring`` for more information.
* The celery daemon can now be supervised (i.e it is automatically
restarted if it crashes). To use this start celeryd with the
``--supervised`` option (or alternatively ``-S``).
* views.apply: View applying a task. Example::
**NOTE** Use with caution, preferably not make this publicly
accessible without ensuring your code is safe!
* Refactored ``celery.task``. It's now split into three modules:
* celery.task
Contains ``apply_async``, ``delay_task``, ``discard_all``, and task
shortcuts, plus imports objects from ``celery.task.base`` and
* celery.task.base
Contains task base classes: ``Task``, ``PeriodicTask``,
``TaskSet``, ``AsynchronousMapTask``, ``ExecuteRemoteTask``.
* celery.task.builtins
Built-in tasks: ``PingTask``, ``DeleteExpiredTaskMetaTask``.
0.3.7 [2008-06-16 11:41 P.M CET]
* **IMPORTANT** Now uses AMQP's ``basic.consume`` instead of
``basic.get``. This means we're no longer polling the broker for
new messages.
* **IMPORTANT** Default concurrency limit is now set to the number of CPUs
available on the system.
* **IMPORTANT** ``tasks.register``: Renamed ``task_name`` argument to
``name``, so
>>> tasks.register(func, task_name="mytask")
has to be replaced with:
>>> tasks.register(func, name="mytask")
* The daemon now correctly runs if the pidlock is stale.
* Now compatible with carrot 0.4.5
* Default AMQP connnection timeout is now 4 seconds.
* ```` was always returning ``True``.
* Only use README as long_description if the file exists so easy_install
doesn't break.
* ``celery.view``: JSON responses now properly set its mime-type.
* ``apply_async`` now has a ``connection`` keyword argument so you
can re-use the same AMQP connection if you want to execute
more than one task.
* Handle failures in task_status view such that it won't throw 500s.
* Fixed typo ``AMQP_SERVER`` in documentation to ``AMQP_HOST``.
* Worker exception e-mails sent to admins now works properly.
* No longer depends on ``django``, so installing ``celery`` won't affect
the preferred Django version installed.
* Now works with PostgreSQL (psycopg2) again by registering the
``PickledObject`` field.
* ``celeryd``: Added ``--detach`` option as an alias to ``--daemon``, and
it's the term used in the documentation from now on.
* Make sure the pool and periodic task worker thread is terminated
properly at exit. (So ``Ctrl-C`` works again).
* Now depends on ``python-daemon``.
* Removed dependency to ``simplejson``
* Cache Backend: Re-establishes connection for every task process
if the Django cache backend is memcached/libmemcached.
* Tyrant Backend: Now re-establishes the connection for every task
0.3.3 [2009-06-08 01:07 P.M CET]
* The ``PeriodicWorkController`` now sleeps for 1 second between checking
for periodic tasks to execute.
0.3.2 [2009-06-08 01:07 P.M CET]
* celeryd: Added option ``--discard``: Discard (delete!) all waiting
messages in the queue.
* celeryd: The ``--wakeup-after`` option was not handled as a float.
0.3.1 [2009-06-08 01:07 P.M CET]
* The `PeriodicTask`` worker is now running in its own thread instead
of blocking the ``TaskController`` loop.
* Default ``QUEUE_WAKEUP_AFTER`` has been lowered to ``0.1`` (was ``0.3``)
0.3.0 [2009-06-08 12:41 P.M CET]
**NOTE** This is a development version, for the stable release, please
see versions 0.2.x.
**VERY IMPORTANT:** Pickle is now the encoder used for serializing task
arguments, so be sure to flush your task queue before you upgrade.
* **IMPORTANT** now returns a celery.result.TaskSetResult
instance, which lets you inspect the status and return values of a
taskset as it was a single entity.
* **IMPORTANT** Celery now depends on carrot >= 0.4.1.
* The celery daemon now sends task errors to the registered admin e-mails.
To turn off this feature, set ``SEND_CELERY_TASK_ERROR_EMAILS`` to
``False`` in your ````. Thanks to Grégoire Cachet.
* You can now run the celery daemon by using ````::
$ python celeryd
Thanks to Grégoire Cachet.
* Added support for message priorities, topic exchanges, custom routing
keys for tasks. This means we have introduced
``celery.task.apply_async``, a new way of executing tasks.
You can use ``celery.task.delay`` and ``celery.Task.delay`` like usual, but
if you want greater control over the message sent, you want
``celery.task.apply_async`` and ``celery.Task.apply_async``.
This also means the AMQP configuration has changed. Some settings has
been renamed, while others are new::
See the entry `Can I send some tasks to only some servers?`_ in the
`FAQ`_ for more information.
.. _`Can I send some tasks to only some servers?`:
.. _`FAQ`:
* Task errors are now logged using loglevel ``ERROR`` instead of ``INFO``,
and backtraces are dumped. Thanks to Grégoire Cachet.
* Make every new worker process re-establish it's Django DB connection,
this solving the "MySQL connection died?" exceptions.
Thanks to Vitaly Babiy and Jirka Vejrazka.
* **IMOPORTANT** Now using pickle to encode task arguments. This means you
now can pass complex python objects to tasks as arguments.
* Removed dependency to ``yadayada``.
* Added a FAQ, see ``docs/faq.rst``.
* Now converts any unicode keys in task ``kwargs`` to regular strings.
Thanks Vitaly Babiy.
* Renamed the ``TaskDaemon`` to ``WorkController``.
* ``celery.datastructures.TaskProcessQueue`` is now renamed to
* The pool algorithm has been refactored for greater performance and
0.2.0 [2009-05-20 05:14 P.M CET]
* Final release of 0.2.0
* Compatible with carrot version 0.4.0.
* Fixes some syntax errors related to fetching results
from the database backend.
0.2.0-pre3 [2009-05-20 05:14 P.M CET]
* *Internal release*. Improved handling of unpickled exceptions,
``get_result`` now tries to recreate something looking like the
original exception.
0.2.0-pre2 [2009-05-20 01:56 P.M CET]
* Now handles unpickleable exceptions (like the dynimically generated
subclasses of ``django.core.exception.MultipleObjectsReturned``).
0.2.0-pre1 [2009-05-20 12:33 P.M CET]
* It's getting quite stable, with a lot of new features, so bump
version to 0.2. This is a pre-release.
* ``celery.task.mark_as_read()`` and ``celery.task.mark_as_failure()`` has
been removed. Use ``celery.backends.default_backend.mark_as_read()``,
and ``celery.backends.default_backend.mark_as_failure()`` instead.
0.1.15 [2009-05-19 04:13 P.M CET]
* The celery daemon was leaking AMQP connections, this should be fixed,
if you have any problems with too many files open (like ``emfile``
errors in ``rabbit.log``, please contact us!
0.1.14 [2009-05-19 01:08 P.M CET]
* Fixed a syntax error in the ``TaskSet`` class. (No such variable
0.1.13 [2009-05-19 12:36 P.M CET]
* Forgot to add ``yadayada`` to install requirements.
* Now deletes all expired task results, not just those marked as done.
* Able to load the Tokyo Tyrant backend class without django
configuration, can specify tyrant settings directly in the class
* Improved API documentation
* Now using the Sphinx documentation system, you can build
the html documentation by doing ::
$ cd docs
$ make html
and the result will be in ``docs/.build/html``.
0.1.12 [2009-05-18 04:38 P.M CET]
* ``delay_task()`` etc. now returns ``celery.task.AsyncResult`` object,
which lets you check the result and any failure that might have
happened. It kind of works like the ``multiprocessing.AsyncResult``
class returned by ``multiprocessing.Pool.map_async``.
* Added dmap() and dmap_async(). This works like the
``multiprocessing.Pool`` versions except they are tasks
distributed to the celery server. Example:
>>> from celery.task import dmap
>>> import operator
>>> dmap(operator.add, [[2, 2], [4, 4], [8, 8]])
>>> [4, 8, 16]
>>> from celery.task import dmap_async
>>> import operator
>>> result = dmap_async(operator.add, [[2, 2], [4, 4], [8, 8]])
>>> result.ready()
>>> time.sleep(1)
>>> result.ready()
>>> result.result
[4, 8, 16]
* Refactored the task metadata cache and database backends, and added
a new backend for Tokyo Tyrant. You can set the backend in your django
settings file. e.g::
CELERY_RESULT_BACKEND = "database"; # Uses the database
CELERY_RESULT_BACKEND = "cache"; # Uses the django cache framework
CELERY_RESULT_BACKEND = "tyrant"; # Uses Tokyo Tyrant
TT_HOST = "localhost"; # Hostname for the Tokyo Tyrant server.
TT_PORT = 6657; # Port of the Tokyo Tyrant server.
0.1.11 [2009-05-12 02:08 P.M CET]
* The logging system was leaking file descriptors, resulting in
servers stopping with the EMFILES (too many open files) error. (fixed)
0.1.10 [2009-05-11 12:46 P.M CET]
* Tasks now supports both positional arguments and keyword arguments.
* Requires carrot 0.3.8.
* The daemon now tries to reconnect if the connection is lost.
0.1.8 [2009-05-07 12:27 P.M CET]
* Better test coverage
* More documentation
* celeryd doesn't emit ``Queue is empty`` message if
0.1.7 [2009-04-30 1:50 P.M CET]
* Added some unittests
* Can now use the database for task metadata (like if the task has
been executed or not). Set ``settings.CELERY_TASK_META``
* Can now run ``python test`` to run the unittests from
within the ``tests`` project.
* Can set the AMQP exchange/routing key/queue using
0.1.6 [2009-04-28 2:13 P.M CET]
* Introducing ``TaskSet``. A set of subtasks is executed and you can
find out how many, or if all them, are done (excellent for progress
bars and such)
* Now catches all exceptions when running ``Task.__call__``, so the
daemon doesn't die. This does't happen for pure functions yet, only
``Task`` classes.
* ``autodiscover()`` now works with zipped eggs.
* celeryd: Now adds curernt working directory to ``sys.path`` for
* The ``run_every`` attribute of ``PeriodicTask`` classes can now be a
``datetime.timedelta()`` object.
* celeryd: You can now set the ``DJANGO_PROJECT_DIR`` variable
for ``celeryd`` and it will add that to ``sys.path`` for easy launching.
* Can now check if a task has been executed or not via HTTP.
* You can do this by including the celery ```` into your project,
>>> url(r'^celery/$', include("celery.urls"))
then visiting the following url,::
this will return a JSON dictionary like e.g:
>>> {"task": {"id": $task_id, "executed": true}}
* ``delay_task`` now returns string id, not ``uuid.UUID`` instance.
* Now has ``PeriodicTasks``, to have ``cron`` like functionality.
* Project changed name from ``crunchy`` to ``celery``. The details of
the name change request is in ``docs/name_change_request.txt``.
0.1.0 [2009-04-24 11:28 A.M CET]
* Initial release