Mark http_exception as async to prevent thread creation. #2922
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…eation. In https://github.com/encode/starlette/blob/master/starlette/_exception_handler.py#L61 we check if the exception_handler is an async function and if not we execute it in a different thread. This is meant to ensure that long-running sync IO operations don't block the main async eventloop. However, in the case of http_exception, a simple function that does not do any io at all the aforementioned logic spawns a thread to run the function. Marking this function async is a simple way of making sure this function does not accidently cause a thread to be created.
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Kludex
approved these changes
Apr 14, 2025
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@Kludex no worries 😄 |
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@Kludex bumping this, would appreciate some help hitting the merge button 😄 |
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Summary
In https://github.com/encode/starlette/blob/master/starlette/_exception_handler.py#L61 we check if the exception_handler is an async function and if not we execute it in a different thread.
This is meant to ensure that long-running sync IO operations don't block the main async eventloop.
However, in the case of http_exception, a simple function that does not do any io at all - the aforementioned logic spawns a thread to run the function.
Marking this function async is a simple way of making sure this function does not accidently cause a thread to be created.
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