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0 pointsBugsJustFindMe1y ago0 comments

> Python isn't all that different

Again, Python's implementation of asyncio does not allow you to background worker code without explicitly altering that worker code to be aware of asyncio. Threads do. They just don't occupy the same space.

> Also, I was originally asking about free threads...there's multiprocessing

Eh, the obvious reason to not want to use separate processes is a desire for some kind of shared state without the cost or burden of IPC. The fact that you suggested multiprocessing.Pool instead of concurrent_futures.ProcessPoolExecutor and asked about manual pool management feels like it tells me a little bit about where your head is at here wrt Python.

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hot_gril1y ago

Basically true in JS too. You're not supposed to do blocking calls in async code. You also can't "await" an async call inside a non-async func, though you could fire-and-forget it.

Right, but how often does a Python program have complex shared state across threads, rather than some simple fan-out-fan-in, and also need to take advantage of multiple cores?

nilamo1y ago

The primary thing that tripped me up about async/await, specifically only in Python, is that the called function does not begin running until you await it. Before that moment, it's just an unstarted generator.

To make background jobs, I've used the class-based version to start a thread, then the magic method that's called on await simply joins the thread. Which is a lot of boilerplate to get a little closer to how async works in (at least) js and c#.

LegionMammal9781y ago

Rust's version of async/await is the same in that respect, where futures don't do anything until you poll them (e.g., by awaiting them): if you want something to just start right away, you have to call out to the executor you're using, and get it to spawn a new task for it.

Though to be fair, people complain about this in Rust as well. I can't comment much on it myself, since I haven't had any need for concurrent workloads that Rayon (a basic thread-pool library with work stealing) can't handle.

pests1y ago

That is a common split in language design decisions. I think the argument for the python-style where you have to drive it to begin is more useful as you can always just start it immediately but also let's you delay computation or pass it around similar to a Haskell thunk.

kristjansson1y ago

There is also https://docs.python.org/3/library/asyncio-task.html#eager-ta... if you want your task to start on creation.

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