Store and use the current task of asyncio on thread state for all threads

[kumaraditya303]

asyncio currently stores the current task in a global dict _current_tasks and on thread state. Storing it on dict in free-threading will cause significant contention under many threads and such I propose to remove it and always rely on the task stored on the thread state.

This has the added benefit that external introspection will always have the correct task and it will be guaranteed by this implementation while also being performant.

cc @asvetlov @ambv @pablogsal

Linked PRs

• gh-129898: per-thread current task implementation in asyncio #129899

Hi everyone,

This is a great improvement for asyncio, especially considering the potential contention issues in a free-threading environment. Storing the current task directly in the thread state seems like a more scalable and efficient approach.

I see that PR #129899 is already in progress. Are there any specific areas where feedback or testing would be most helpful? I’d love to understand if there are edge cases or performance benchmarks that need validation before merging.

Looking forward to your thoughts! Thanks for all the hard work on this!