84 lines
3.2 KiB
ReStructuredText
84 lines
3.2 KiB
ReStructuredText
.. _glossary:
|
|
|
|
Glossary
|
|
========
|
|
|
|
.. glossary::
|
|
:sorted:
|
|
|
|
acknowledged
|
|
Workers acknowledge messages to signify that a message has been
|
|
handled. Failing to acknowledge a message
|
|
will cause the message to be redelivered. Exactly when a
|
|
transaction is considered a failure varies by transport. In AMQP the
|
|
transaction fails when the connection/channel is closed (or lost),
|
|
but in Redis/SQS the transaction times out after a configurable amount
|
|
of time (the ``visibility_timeout``).
|
|
|
|
ack
|
|
Short for :term:`acknowledged`.
|
|
|
|
request
|
|
Task messages are converted to *requests* within the worker.
|
|
The request information is also available as the task's
|
|
:term:`context` (the ``task.request`` attribute).
|
|
|
|
calling
|
|
Sends a task message so that the task function is
|
|
:term:`executed <executing>` by a worker.
|
|
|
|
kombu
|
|
Python messaging library used by Celery to send and receive messages.
|
|
|
|
billiard
|
|
Fork of the Python multiprocessing library containing improvements
|
|
required by Celery.
|
|
|
|
executing
|
|
Workers *execute* task :term:`requests <request>`.
|
|
|
|
apply
|
|
Originally a synonym to :term:`call <calling>` but used to signify
|
|
that a function is executed by the current process.
|
|
|
|
context
|
|
The context of a task contains information like the id of the task,
|
|
it's arguments and what queue it was delivered to.
|
|
It can be accessed as the tasks ``request`` attribute.
|
|
See :ref:`task-request-info`
|
|
|
|
idempotent
|
|
Idempotence is a mathematical property that describes a function that
|
|
can be called multiple times without changing the result.
|
|
Practically it means that a function can be repeated many times without
|
|
unintented effects, but not necessarily side-effect free in the pure
|
|
sense (compare to :term:`nullipotent`).
|
|
|
|
nullipotent
|
|
describes a function that will have the same effect, and give the same
|
|
result, even if called zero or multiple times (side-effect free).
|
|
A stronger version of :term:`idempotent`.
|
|
|
|
reentrant
|
|
describes a function that can be interrupted in the middle of
|
|
execution (e.g. by hardware interrupt or signal) and then safely
|
|
called again later. Reentrancy is not the same as
|
|
:term:`idempotence <idempotent>` as the return value does not have to
|
|
be the same given the same inputs, and a reentrant function may have
|
|
side effects as long as it can be interrupted; An idempotent function
|
|
is always reentrant, but the reverse may not be true.
|
|
|
|
cipater
|
|
Celery release 3.1 named after song by Autechre
|
|
(http://www.youtube.com/watch?v=OHsaqUr_33Y)
|
|
|
|
prefetch multiplier
|
|
The :term:`prefetch count` is configured by using the
|
|
:setting:`CELERYD_PREFETCH_MULTIPLIER` setting, which is multiplied
|
|
by the number of pool slots (threads/processes/greenthreads).
|
|
|
|
prefetch count
|
|
Maximum number of unacknowledged messages a consumer can hold and if
|
|
exceeded the transport should not deliver any more messages to that
|
|
consumer. See :ref:`optimizing-prefetch-limit`.
|