I am agreeIt does make sense to have a barrier synchronization primitive for asyncio.The idea is to make a coroutine block until at least X coroutines are waiting to enter the barrier.This is very useful, if certain actions need to be synchronized.
I 'd like too, with a similar designRecently, I had to implement a barier myself for our use case. See code below:
It is simple to implement, but I too would like to have one for asyncio, in order to be consistent with the concurrency primitives we have for threading.
Jonathan
class Barier:
"""
Make a coroutine block until there are at least X waiters.
Similar to the threading Barier objects but for asyncio:
https://docs.python.org/3/library/threading.html#barrier-objects
"""
def __init__(self, parties: int) -> None:
self.parties = parties
self._waiting: int
self._event = asyncio.Event()
def add_one(self) -> None:
self._waiting += 1
if self._waiting == self.parties:
self._event.set()
async def wait(self, worker: "Worker") -> None:
"""
Wait until all we have at least `parties` waiters.
"""
self.add_one()
await self._event.wait()
Le jeu. 25 févr. 2021 à 16:42, Barry Scott <barry@barrys-emacs.org> a écrit :
> On 25 Feb 2021, at 13:14, Yves Duprat <yduprat@gmail.com> wrote:
>
> Hi,the list,
>
> I'm wondering why Barrier object does not exist in the synchronization primitives of the asyncio lib while it is present in threading and multiprocessing libs ?
> This may not be the right place to ask this question, but I never found an answer on the web.
> Thanks for your help.
I'm assuming that the barrier you are speaking of is the mechanism that is used to
synchronise threads/processes running in parallel to prevent data races.
With async code that is never an issue. Each function runs to completion uninterrupted.
There are no data races. Each time a async function runs it can know that the state of
the objects it uses will not be changed while it is running.
Barry
>
> Yves
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