"Marko Rauhamaa" wrote in message news:87lh6ys052....@elektro.pacujo.net...
"Frank Millman" <fr...@chagford.com>:
> When shutting the main program down, I want to stop the task, but I
> cannot figure out how to stop it cleanly - i.e. wait until it has
> finished the current task and possibly performed some cleanup, before
> continuing.
Here (and really, only here) is where asyncio shows its superiority over
threads: you can multiplex.
You should
await asyncio.wait(..., return_when=asyncio.FIRST_COMPLETED)
to deal with multiple alternative stimuli.
Thanks, Marko, that works very well.
It took me a while to get it working, because I initiate shutting down the
program from another thread. Eventually I figured out that I could put all
my event loop shutdown procedures into a coroutine, and then call
asyncio.run_coroutine_threadsafe() from the main thread.
Now I just have one problem left. I will keep experimenting, but if someone
gives me a hint in the meantime it will be appreciated.
I run my background task like this -
stop_task = False
async def background_task():
while not stop_task:
await perform_task()
await asyncio.sleep(10)
I stop the task by setting stop_task to True. It works, but it waits for the
10-second sleep to expire before it is actioned.
With threading, I could set up a threading.Event(), call
evt.wait(timeout=10) to run the loop, and evt.set() to stop it. It stopped
instantly.
Is there an equivalent in asyncio?
Thanks
Frank
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