Should worker do better than asyncio.to_thread()?
#2424
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I use Pyodide both in main thread and in a worker. As far as I understand, worker is a proper Web way to perform heavy calculations (I do processing of large images with Pillow/NumPy) without blocking main thread. I invested some effort into creating a worker, it was not easy, and it turned out that things don't run noticeably faster than without a worker. Also, when non-NumPy, GIL-holding code like I'm a Python guy, not a Web/JS guy, so I could easily miss something important. Thanks! |
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Replies: 1 comment 4 replies
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it's literally: <script type="py" src="./your_code.py" worker></script>what was difficult?
without any code or minimal reproducible example, it's hard to guess/help but I believe you are resizing via DOM elements? I can write a
usually the ideal scenario is MicroPython on the main thread for fast bootstrap and Pyodide workers. If you name your workers you can reach their exported features/utilities via the dedicated API. See the second part of the docs: https://docs.pyscript.net/2025.11.2/user-guide/workers/#worker-interactions edit the other possibility is that you have a single thread environment so everything computes on the same CPU and workers can't do magic |
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Creating a worker is nice, learning to parse JsProxies was difficult. My expectation from the docs was I just call a Python function and it gets magically called in worker. In turned out to be not that simple, and that was rather frustrating. I'm not complaining, I understand why is that so, but it took me a couple days to understand the process and write the necessary decorators to make Python calling comfortable. I didn't manage the CORS problems, so I have a worker with
Hmm, that's the answer I was looking for. I'll keep digging why it freezes for me.
I understand that, but I have a lot of logic and DOM interactions in main, and feel uncomfortable to write on Python 3.4, I love new language features too much. :) Moving all that stuff to a worker seems out of bounds for me now, those CORS limitations are too complicated.
Is it a realistic possibility? I have the latest macOS and Chrome. |
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we have at least 3 workarounds for that ...
I hope one of these work ... if you don't have SharedArrayBuffer, you are basically not using full PyScript potentials but hey, if no DOM access is needed in the worker, then it might be a solution ... still, stuff that runs in a Worker cannot block the main thread, if it does, you leaked some computation somewhere or you are computing images heavily on the main thread ... I've no idea without examples. |
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I'm still contemplating about it. |
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I'm planning to use GitHub Pages for hosting, so no chance, as far as I understand.
You were right :), |
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it's literally:
what was difficult?
without any code or minimal reproducible example, it's hard to guess/help but I believe you are resizing via DOM elements?
I can write a
while True: passloop in a worker and the main thread would always be responsive so I am pretty sure you are not using a worker or not computing within the worker.usually the ideal scenario is MicroPython on the main thread for fast bootstrap and Pyodide workers. If y…