[Question] add/alter controls and update from different threads?

[gbrandt]

Question

Is it ok to add controls or edit controls on a page from a thread and call update from that thread? From multiple threads at the same time? Or does Flet get confused. I’ve been doing it with some success but have recently gotten strange errors like a button not being clickable even though it has an on click handler.

Code sample

No response

Error message

No response

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• I have searched for answers to my question both in the issues and in previous discussions.

[hoonlight]

Threading

Technically, nobody will stop you from using threading library in async app, but it would be a bad idea. asyncio versions of locks, queues and tasks, used by Flet API are not thread-safe and, for example, calling await page.update_async() from multiple threads will lead to unpredictable results. Also, threading library is not supported by Pyodide if you decide to deploy your app as a static website.

To run something in the background use asyncio.create_task(). For example, an async version of "countdown" control from User controls guide would be:

https://flet.dev/docs/guides/python/async-apps