Python Asyncio
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Python Asyncio
1–10 of 188 posts
Re: Python Asyncio
#2Important to note:
> They are suited to non-blocking I/O with subprocesses and sockets, however, blocking I/O and CPU-bound tasks can be used in a simulated non-blocking manner using threads and processes under the covers.
If you're using it for anything besides slow async I/O, you're going to have to do some heavy lifting.
I've also found the actual asyncio implementation in CPython to be slow. Measuring purely event-loop overhead (and doing little/nothing in the async spawned tasks), it's 120x slower than JavaScript on my machine. https://twitter.com/bwasti/status/1572339846122991617
Re: Python Asyncio
#3Missing yet very important topics: redis & db drivers in async. Or even async ORM.
Re: Python Asyncio
#4Is this negligible in performance until the GIL radically changes? I find parallel processing has muc larger increases in speed.
Re: Python Asyncio
#5Important to note: > They are suited to non-blocking I/O with subprocesses and sockets, however, blocking I/O and CPU-bound tasks can be used in a simulated non-blocking manner using threads and processes under the covers. If you're using it for anything besides slow async I/O, you're going to have to do some heavy lifting. I've also found the actual asyncio implementation in CPython to be slow. Measuring purely even…
Ok. This is what has been a huge hangup for me.
It really seems that if you're doing asyncio, you must do EVERYTHING async, it's like asyncio takes over (infects?) the entire program.
Re: Python Asyncio
#6Too bad Python couldn't go the gevent road. At least Java is doing with Project Loom and looks like it will be very successful.
Re: Python Asyncio
#7Maybe off-topic, but my advice would be: if you need this guide, consider to switch to another language, if that's possible. In our company we switched to Go, and all those asyncio problems were magically solved.
Re: Python Asyncio
#8Important to note: > They are suited to non-blocking I/O with subprocesses and sockets, however, blocking I/O and CPU-bound tasks can be used in a simulated non-blocking manner using threads and processes under the covers. If you're using it for anything besides slow async I/O, you're going to have to do some heavy lifting. I've also found the actual asyncio implementation in CPython to be slow. Measuring purely even…
Ok. This is what has been a huge hangup for me. It really seems that if you're doing asyncio, you must do EVERYTHING async, it's like asyncio takes over (infects?) the entire program.
Yes. Unless you (and your team) are well-versed with python and how async works, and all the dependencies you use, is it very easy to accidentally do something blocking in async and lose most of the benefits.
Re: Python Asyncio
#9Important to note: > They are suited to non-blocking I/O with subprocesses and sockets, however, blocking I/O and CPU-bound tasks can be used in a simulated non-blocking manner using threads and processes under the covers. If you're using it for anything besides slow async I/O, you're going to have to do some heavy lifting. I've also found the actual asyncio implementation in CPython to be slow. Measuring purely even…
Ok. This is what has been a huge hangup for me. It really seems that if you're doing asyncio, you must do EVERYTHING async, it's like asyncio takes over (infects?) the entire program.
To be fair this is not really asyncio's fault, the same happens in most languages unless the runtime does some magic like scheduling blocking calls in a background thread (which can also be done with asyncio).
Re: Python Asyncio
#10Not complete - doesn't include Task Groups [1]
In fairness they were only included in asyncio as of Python 3.11, which was released a couple of weeks ago.
These were an idea originally from Trio [2] where they're called "nurseries" instead of "task groups". My view is that you're better off using Trio, or at least anyio [3] which gives a Trio-like interface to asyncio. One particularly nice thing about Trio (and anyio) is that there's no way to spawn background tasks except to use task groups i.e. there's no analogue of asyncio's create_task() function. That is good because it guarantees that no task is ever left accidentally running in the background and no exception left silently uncaught.
[1] https://docs.python.org/3/library/asyncio-task.html#task-gro...