prompt-toolkit / prompt-toolkit/python-prompt-toolkit
Calling create_background_task() from other threads
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Description
Calling create_background_task from a thread that isn't the main thread raises RuntimeError:
RuntimeError: There is no current event loop in thread 'Thread-1'.
The issue is that create_background_task uses asyncio.get_event_loop to get the loop, which only guarantees to return a loop in the main thread and raises the error above otherwise.
Storing the event loop on the Application instance in __init__ (run would probably be better?) and using that in create_background_task instead of calling get_event_loop seems to work fine for me. Would this be the correct fix for this issue?
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First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by locating create_background_task and the Application lifecycle, especially init and run, then trace how asyncio.get_event_loop is currently used. Reproduce the failure from a non-main thread and verify that the completed change allows the task to be created there without raising the reported RuntimeError.
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Assessment
- Tech stack
- python
- Domain
- cli
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100