Add thread safety checks to async_create_task

[bdraco]

Proposed change

Calling async_create_task from a thread other than the event loop thread almost always results in a fast crash. Since most internals are using async_create_background_task or other task APIs, the performance impact of adding a check here is not so bad, and this is the one integrations seem to get wrong the most, add a thread safety check here.

Reasoning: eager_start is now the default and any unsafe thread operations start right away, so mistakes (generally in custom components) calling from the wrong thread have a higher impact. While it’s nicer to crash quickly so mistakes can be found as opposed to crashing randomly, which makes for hard-to-find issues, in the short term, we need a way to catch these mistakes in integrations (custom components) even if there is a performance cost.

We turned on asyncio debug in April 2024 in the dev containers in the hope of catching some of the issues that have been reported. It will take a while to get all the issues fixed in custom components.

In 2025.5 we should guard the verify_event_loop_thread check with a check for the hass.config.debug flag being set as long term we don't want to be checking this in production environments since it is a performance hit. For context, the run time of the verify_event_loop_thread is slightly faster than asyncio.get_running_loop() so the while the performance hit isn't large its still undesirable.

Type of change

• Dependency upgrade
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[balloob]

Let's give it a shot to see how much things we catch.

Btw, one thing I was wondering is if verify_event_loop_thread should include a suggestion what method to use instead (for another PR).

[bdraco]

Btw, one thing I was wondering is if verify_event_loop_thread should include a suggestion what method to use instead (for another PR).

I was thinking on having it spit out a url and creating pages on the development site to explain what to do instead for each one. Before I do that I need to move all the ones that are currently hitting on async fire in the other registries sooner so they give a useful suggestion