Pure async, single-threaded application

[davidbrochart]

I'd like to run a Textual application in WASM, where threads are not available. I understand that Textual uses threads for messages, but I'm wondering if there could be a mode where Textual runs in a pure-async environment, in a single thread?

[willmcgugan]

It's certainly possible. Textual launches threads in the driver, one for processing input, and another for writing output. That could be replaced with pure-async and no threads. Not a small job though.

Some apps may also use threaded workers, which couldn't easily be converted in to async. At least now without introducing freezes in the UI.

[davidbrochart]

Some apps may also use threaded workers, which couldn't easily be converted in to async. At least now without introducing freezes in the UI.

Yes, if a threaded worker does long-running blocking operations then this part would need to be redesigned, but that would be my responsibility to ensure that the app is convertible to WASM.

Textual launches threads in the driver, one for processing input, and another for writing output. That could be replaced with pure-async and no threads. Not a small job though.

I'm wondering if that could be included in the work @graingert is doing on switching to AnyIO? Basically removing the to_thread/from_thread if the app is running in "no-thread mode"?

[willmcgugan]

I'm wondering if that could be included in the work @graingert is doing on switching to AnyIO? Basically removing the to_thread/from_thread if the app is running in "no-thread mode"?

I don't think so. The driver launches threads via the thread module, not via asyncio. I suspect the easiest integration would be to implement a WASM driver that used async tasks rather than threads.