This document is for Kombu's development version, which can be significantly different from previous releases. Get the stable docs here: 5.0.

Semaphores - kombu.asynchronous.semaphore

Semaphores and concurrency primitives.

class kombu.asynchronous.semaphore.DummyLock[source]

Pretending to be a lock.

class kombu.asynchronous.semaphore.LaxBoundedSemaphore(value: int)[source]

Asynchronous Bounded Semaphore.

Lax means that the value will stay within the specified range even if released more times than it was acquired.

Example

>>> x = LaxBoundedSemaphore(2)

>>> x.acquire(print, 'HELLO 1')
HELLO 1

>>> x.acquire(print, 'HELLO 2')
HELLO 2

>>> x.acquire(print, 'HELLO 3')
>>> x._waiters   # private, do not access directly
[print, ('HELLO 3',)]

>>> x.release()
HELLO 3
acquire(callback: Callable[P, None], *partial_args: P.args, **partial_kwargs: P.kwargs) → bool[source]

Acquire semaphore.

This will immediately apply callback if the resource is available, otherwise the callback is suspended until the semaphore is released.

Parameters

  • callback (Callable) – The callback to apply.

  • *partial_args (Any) – partial arguments to callback.

clear() → None[source]

Reset the semaphore, which also wipes out any waiting callbacks.

grow(n: int = 1) → None[source]

Change the size of the semaphore to accept more users.

release() → None[source]

Release semaphore.

Note

If there are any waiters this will apply the first waiter that is waiting for the resource (FIFO order).

shrink(n: int = 1) → None[source]

Change the size of the semaphore to accept less users.